U.S. patent application number 13/818636 was filed with the patent office on 2013-07-25 for ester oils.
This patent application is currently assigned to PANOLIN Holding AG. The applicant listed for this patent is Patrick Lammle, Bernardo Walterspiel, Mathias Woydt. Invention is credited to Patrick Lammle, Bernardo Walterspiel, Mathias Woydt.
Application Number | 20130190217 13/818636 |
Document ID | / |
Family ID | 44644835 |
Filed Date | 2013-07-25 |
United States Patent
Application |
20130190217 |
Kind Code |
A1 |
Lammle; Patrick ; et
al. |
July 25, 2013 |
ESTER OILS
Abstract
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.
Inventors: |
Lammle; Patrick; (Madetswil,
CH) ; Walterspiel; Bernardo; (Kreuzlingen, CH)
; Woydt; Mathias; (Berlin-Dahlem, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lammle; Patrick
Walterspiel; Bernardo
Woydt; Mathias |
Madetswil
Kreuzlingen
Berlin-Dahlem |
|
CH
CH
DE |
|
|
Assignee: |
PANOLIN Holding AG
Madetswil
CH
|
Family ID: |
44644835 |
Appl. No.: |
13/818636 |
Filed: |
August 25, 2011 |
PCT Filed: |
August 25, 2011 |
PCT NO: |
PCT/CH11/00194 |
371 Date: |
April 9, 2013 |
Current U.S.
Class: |
508/496 ;
554/121; 560/190; 560/204 |
Current CPC
Class: |
C10N 2040/08 20130101;
C10N 2020/02 20130101; C10N 2020/071 20200501; C10N 2020/069
20200501; C10N 2020/081 20200501; C10N 2030/02 20130101; C10M
2207/2815 20130101; C10M 105/38 20130101; C10M 2207/2835 20130101;
C10N 2030/74 20200501; C10N 2030/64 20200501; C10M 105/36 20130101;
C10M 2207/2825 20130101; C10N 2030/06 20130101 |
Class at
Publication: |
508/496 ;
560/190; 554/121; 560/204 |
International
Class: |
C10M 105/36 20060101
C10M105/36 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2010 |
CH |
1378/10 |
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.
Description
TECHNICAL FIELD
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] However, the preparation of known esters is comparatively
complex, and they are correspondingly comparatively uneconomic.
[0009] 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
[0010] 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.
[0011] A first solution to the problem is defined by the features
of claims 1 and 41.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] Renewable raw materials can be distinguished from
non-renewable raw materials from fossil sources particularly
through the proportion of the radioactive .sup.14C carbon isotope
in the raw material. Raw materials from fossil sources, owing to
their age, have essentially no .sup.14C carbon isotopes, whereas a
characteristic proportion of the .sup.14C carbon isotope is present
in renewable raw materials. .sup.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 (.sup.14C) to non-radioactive carbon (.sup.12C
and .sup.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.
[0017] The radiocarbon method used to determine the proportion of
.sup.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 .sup.14C carbon isotopes over the course of periods in the
history of the earth.
[0018] 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 .sup.14C
to .sup.12C in the product to be tested is determined relative to a
standard compound (oxalic acid).
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] As has been found, the vaporization losses (NOACK) of the
inventive ester oils are also relatively low.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] Under some circumstances, however, mono- or polyunsaturated
polycarboxylic acids can be used for specific purposes.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] In principle, however, it is also possible to use other
polycarboxylic acids, for example tricarboxylic acids.
[0039] Advantageously, the dicarboxylic acid comprises especially
adipic acid (1,6-hexanedioic acid; HOOC--C.sub.4H.sub.8--COOH),
suberic acid (octanedioic acid; HOOC--C.sub.6H.sub.12--COOH),
azelaic acid (nonanedioic acid; HOOC--C.sub.7H.sub.14--COOH),
sebacic acid (decanedioic acid; HOOC--C.sub.8H.sub.16--COOH),
dodecanedioic acid (HOOC--C.sub.10H.sub.20--COOH) and/or brassylic
acid (HOOC--C.sub.11H.sub.22--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.
[0040] 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.
[0041] 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.
[0042] 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;
C.sub.8H.sub.12O.sub.4; M.sub.w=172.2] and/or
1,4-cyclohexanedicarboxylic acid [CAS #: 619-82-9;
C.sub.8H.sub.12O.sub.4; M.sub.w=172.2].
[0043] 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.
[0044] More preferably, both the polycarboxylic acid and the
monoalcohols originate from renewable raw materials. It is thus
possible to further improve the aforementioned advantages.
[0045] However, it is also possible in principle to use
monoalcohols from fossil raw materials, if this appears appropriate
to the purpose.
[0046] 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.
[0047] 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.
[0048] In principle, the at least one monoalcohol, however, may
also be mono- or polyunsaturated.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] In principle, however, it is also possible to use branched
monoalcohols in combination with branched polycarboxylic acids.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] Advantageously, the at least one monoalcohol is a fatty
alcohol and especially an unbranched fatty alcohol from the group
of 2-octanol (C.sub.8H.sub.18O), 1-nonanol (C.sub.9H.sub.20O),
1-undecanol (C.sub.11H.sub.24O), 1-dodecanol (C.sub.12H.sub.26O),
1-tetradecanol (C.sub.14H.sub.30O), and/or cetyl alcohol (also
known as 1-hexadecanol; C.sub.16H.sub.34O). 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.
[0058] 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].
[0059] In a further advantageous variant, the at least one
monoalcohol comprises methyltetradecanol (13-methyl-1-tetradecanol;
C.sub.15H.sub.33O). This is a saturated, terminally iso-branched
monoalcohol.
[0060] 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.
[0061] However, other alcohols and/or combinations with other
polycarboxylic acids are also possible in principle.
[0062] 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.
[0063] 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
[C.sub.38H.sub.74O.sub.4; M.sub.w=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).
[0064] According to the application, however, other inventive ester
oils may also be more advantageous.
[0065] A further solution to the problem addressed by the invention
is defined by the features of claims 18 and 42.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] As has been found, the vaporization losses (NOACK) of the
inventive ester oils are also relatively low.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] In principle, the dialcohol may also be mono- or
polyunsaturated.
[0082] 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.
[0083] 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 (--CH.sub.3) 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 (.eta..sub.100.degree. C.=4.56
mm.sup.2/s, .eta..sub.-40.degree. C.=14.165 mm.sup.2/s (capillary),
VI=123, pour point=-51.degree. C.)
[0084] 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.
[0085] In principle, however, in place of or in addition to methyl
branches, other branches are also possible, for example ethyl
and/or propyl branches.
[0086] 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.
[0087] 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.
[0088] 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.
[0089] The dialcohol advantageously comprises one or more
representatives from the group of 1,6-hexanediol
(HO--C.sub.6H.sub.12--OH), 1,7-heptanediol
(HO--C.sub.7H.sub.14--OH), 1,8-octanediol (HO--C.sub.8H.sub.16--OH)
1,9-nonanediol (HO--C.sub.9H.sub.18--OH) 1,10-decanediol
(HO--C.sub.10H.sub.20--OH), 1,12-dodecanediol
(HO--C.sub.12H.sub.24--OH), 1,13-tridecanediol
(HO--C.sub.13H.sub.26--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.
[0090] 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.
[0091] 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.
[0092] 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.
[0093] More preferably, both the dialcohol and the monocarboxylic
acid originate from renewable raw materials. It is thus possible to
further improve the aforementioned advantages.
[0094] However, it is also possible in principle to use
monocarboxylic acids from fossil raw materials, if this appears
appropriate to the purpose.
[0095] 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.
[0096] 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.
[0097] 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.
[0098] In another advantageous variant, the at least one
monocarboxylic acid, however, may also be branched.
[0099] 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.
[0100] 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.
[0101] In principle, however, it is also possible to use branched
monocarboxylic acids in combination with branched dialcohols.
[0102] 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.
[0103] 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.
[0104] 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 (C.sub.7H.sub.15--COOH; also referred to as octanoic acid),
pelargonic acid (C.sub.8H.sub.17--COOH; also referred to as
nonanoic acid), capric acid (C.sub.9H.sub.19--COOH; also referred
to as decanoic acid), undecanoic acid (C.sub.10H.sub.21--COOH),
lauric acid (C.sub.11H.sub.23--COOH; also referred to as dodecanoic
acid), tridecanoic acid (C.sub.12H.sub.25--COOH), myristic acid
(C.sub.13H.sub.27--COOH; also referred to as tetradecanoic acid),
hexanedecanoic acid (C.sub.15H.sub.31--COOH, also referred to as
palmitic acid), octanedecanoic acid (C.sub.17H.sub.35--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.
[0105] 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.
[0106] However, it is also possible in principle to use other
dialcohols and/or combinations with other polycarboxylic acids.
[0107] In a further optional variant, the monocarboxylic acid is a
cyclic monocarboxylic acid, especially a saturated cyclic
monocarboxylic acid. A suitable example is
CH.sub.3--(CH.sub.2).sub.x--C.sub.6H.sub.10--(CH.sub.2).sub.y--COOH,
where x+y=10, more preferably 9-(2'-n-propylcyclohexyl)nonanoic
acid
[CH.sub.3--(CH.sub.2).sub.2--C.sub.6H.sub.10--(CH.sub.2).sub.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)].
[0108] 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.
[0109] 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.
[0110] 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.
[0111] In principle, a lower proportion than 25% of renewable raw
materials may also be present. However, the aforementioned
advantages are absent under some circumstances.
[0112] 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.
[0113] 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.
[0114] 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.
[0115] 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.
[0116] 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.
[0117] 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.
[0118] 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.
[0119] In a preferred variant, the lubricant and/or the hydraulic
fluid comprises additives for improving the properties.
[0120] Advantageously, the additives used are antioxidants,
antiwear additives, metal deactivators, corrosion inhibitors and/or
antifoams.
[0121] 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.
[0122] 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.
[0123] More particularly, the lubricant and/or the hydraulic fluid
comprise both aminic antioxidants and phenolic antioxidants.
[0124] 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.
[0125] 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.
[0126] Suitable corrosion inhibitors are, for example, alkylated
succinic acid and/or derivatives thereof, for example monoesters,
monoamides and/or amine phosphates.
[0127] The proportion of corrosion inhibitors is especially 0.01-3%
by weight, preferably 0.1-0.4% by weight.
[0128] 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.
[0129] 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.
[0130] 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; .omega.-9), linoleic acid (C18:2; 9Z, 12Z;
.omega.-6), gadoleic acid (C20:1; 11Z, .omega.-9), erucic acid
(C22:1, 13Z; .omega.-9), petroselinic acid (C18:1; 6Z; .omega.-6),
arachidonic acid (C20:4; 5Z, 8Z, 11Z, 14Z; .omega.-6) and/or
generally .omega.-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 .omega. 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 (".omega.") in the carbon
chain.
[0131] 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; .omega.-9),
lesquerolic acid (C20:1; Z11; 14-hydroxy) and/or vernolic acid
(C18:1; 9Z; 13-epoxy; .omega.-9).
[0132] 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.
[0133] In principle, however, it is also possible to resort to
other sources if this appears more advantageous.
[0134] 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
[0135] The appended drawing show:
[0136] 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;
[0137] FIG. 2a,b four diagrams which show the coefficients of
friction (f), the standard force (F.sub.N) and stroke (dx) in the
friction-wear test on which FIG. 1 is based with diisotridecyl
adipate as a function of time;
[0138] FIG. 3a,b four diagrams which show the coefficients of
friction (f), the standard force (F.sub.N) and stroke (dx) in the
friction-wear test on which FIG. 1 is based with di(isotridecyl)
dodecanedioate (C12D13) as a function of time;
[0139] FIG. 4a,b four diagrams which show the coefficients of
friction (f), the standard force (F.sub.N) 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
[0140] Fatty acids, such as oleic acid, linoleic acid, gadoleic
acid, erucic acid, petroselinic acid, arachidonic acid, or
.omega.-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.
[0141] 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
[0142] 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)
[0143] Adipic acid [Chemical Abstracts number (CAS #): 124-04-09;
HOOC--(CH.sub.2).sub.4--COOH; molecular weight (M.sub.w)=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 H.sub.2O.sub.2 (30%) using a phase transfer
catalyst (quaternary ammonium hydrosulfate or
Na.sub.2WO.sub.2+[CH.sub.3(n-C.sub.8H.sub.17).sub.3N]HSO.sub.4).
[0144] Adipic acid from renewable raw materials can be obtained,
for example, from xylose derivatives (C.sub.5 sugars), by
decarbonylation of furfuryl alcohol (furfural,
C.sub.5H.sub.4O.sub.2). It can likewise be obtained from glucose
(C.sub.6 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 .omega.-6-fatty acid, for example
gamma-linolenic acid [C.sub.18H.sub.30O.sub.2; M.sub.w=278.43].
[0145] The oxidative cleavage of gamma-linolenic acid as
.omega.-6-fatty acid gives 2 mol of adipic acid as well as 2 mol of
malonic acid, which constitutes an effective yield.
[0146] It is also possible to prepare adipic acid by oxidative
cleavage of arachidonic acid [CAS #: 506-32-11;
C.sub.20H.sub.32O.sub.2; M.sub.w=304.46].
[0147] 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.
[0148] Petroselinic acid [CAS #: 593-39-51,
C.sub.18H.sub.34O.sub.2; M.sub.w=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; M.sub.w=200.31). The latter can then be
reduced, for example with lithium aluminum hydride, to 1-dodecanol
(lauryl alcohol; C.sub.12H.sub.26O; M.sub.w=186.33). Petroselinic
acid itself is present in coriander seeds, but also in fennel.
Branched Adipic Acid Derivatives (C9)
[0149] 3-Methyladipic acid [CAS #: 3058-01-3;
C.sub.7H.sub.12O.sub.4; M.sub.w=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).
[0150] 2,2,3-Trimethyladipic acid [CAS #: 28472-18-6;
C.sub.9H.sub.16O.sub.4; M.sub.w=188.2], 2,2,4-trimethyladipic acid
[CAS #: 3586-39-8; C.sub.9H.sub.16O.sub.4; M.sub.w=188.2] and
2,4,4-trimethyladipic acid [CAS #: 3937-59-5;
C.sub.9H.sub.16O.sub.4; M.sub.w=188.2] are multiply methyl-branched
derivatives of adipic acid which are likewise commercially
available.
Azelaic Acid (C9)
[0151] Azelaic acid [CAS #: 123-99-9; C.sub.9H.sub.16O.sub.4; with
M.sub.w=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.degree. C. or the reagents H.sub.2O.sub.2, NaOCl (with
ruthenium catalyst), hot nitric acid, KMnO.sub.4 or chromic acid. A
by-product additionally obtained is pelargonic acid [CAS #:
112-05-0; C.sub.9H.sub.18O.sub.2; with M.sub.w=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.
[0152] The same applies mutatis mutandis in the case of use of
elaidic acid, i.e. trans-9-octadecenoic acid [CAS #: 112-79-8;
C.sub.18H.sub.34O.sub.2], which corresponds to the trans isomer of
oleic acid.
[0153] The pelargonic acid obtained can be reduced to 1-nonanol
[CAS #: 143-08-61, M.sub.w=144.29] as a C.sub.9 alcohol, in order
to use it as a renewable alcohol in a dicarboxylic ester.
[0154] Azelaic acid, however, is also obtainable in the same way
from gadoleic acid, i.e. eicosenoic acid [CAS #: 267634-41-0;
C20:1; (-9; M.sub.w=310.51] by oxidative cleavage. A by-product
formed is undecanoic acid [CAS #: 112-37-8; M.sub.w=186.30] as a
C.sub.1l-monocarboxylic acid, which can be reduced to n-undecanol
[CAS #: 112-45-2; C.sub.11H.sub.24O; M.sub.w=172.30].
Brassylic Acid (C13)
[0155] Brassylic acid is obtainable via cis-erucic acid, i.e.
cis-13-docosenoic acid [CAS #: 112-86-7; C22:1; co-13;
M.sub.w=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;
C.sub.13H.sub.24O.sub.4; M.sub.w=244.3], as the saturated C.sub.13
dicarboxylic acid.
Suberic Acid (C8)
[0156] 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.
[0157] Cork powder can be cleaved to suberic acid by oxidation with
HNO.sub.3. 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].
[0158] Specifically, suberic acid, i.e. octanedioic acid [CAS #:
505-48-6; C.sub.8H.sub.14O.sub.4; M.sub.w=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;
C.sub.18H.sub.34O.sub.3; M.sub.w=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)].
[0159] By an alkaline cleavage with NaOH at 180-270.degree. C.,
sebacic acid sodium salt and 2-octanol, i.e. capryl alcohol
[C.sub.8H.sub.18O; M.sub.w=130.22], are obtained.
Dodecanedioic Acid (C12)
[0160] The seed of Lesquerella contains approx. 55-60% of the
hydroxy fatty acid 14-hydroxy-cis-11-eicosanoic acid [CAS #:
4103-20-2; C.sub.20H.sub.38O.sub.3; M.sub.w=326.51], which can
likewise be cleaved oxidatively in NaOH at 180-250.degree. C. to
dodecanedioic acid [C.sub.12H.sub.22O.sub.4] 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
[0161] Possible sources and processes for preparing 2-octanol
[C.sub.8H.sub.18O; M.sub.w=130.22], 1-nonanol [CAS #: 143-08-61,
C.sub.9H.sub.20O; M.sub.w=144.29], n-undecanol [CAS #: 112-45-2;
C.sub.11H.sub.24O; M.sub.w=172.30], 1-dodecanol (lauryl alcohol;
C.sub.12H.sub.26O; M.sub.w=186.33) have already been mentioned
above in the context of the preparation of dicarboxylic acids from
renewable raw materials.
Isononanol
[0162] 3,5,5-Trimethylhexyl alcohol, i.e. isononyl alcohol [CAS #:
3452-97-9; C.sub.9H.sub.20O; M.sub.w=144.3], a highly branched
isomer of nonanol, is sold by Exxon and Kyowa Hakko Kogyo Co.
Ltd.
1-Decanol
[0163] 1-Decanol [CAS #: 112-30-1; C.sub.10H.sub.22O;
M.sub.w=158.3] is obtainable, for example, by hydrogenation of
capric acid (C.sub.9H.sub.19COOH). 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
[0164] Isodecanol [CAS #: 25399-17-7; C.sub.10H.sub.22O;
M.sub.w=158.3] is obtainable, for example, under the "EXXAL" trade
name via Exxon. In addition, mixtures with C.sub.9-C.sub.11
alcohols rich in C.sub.10 alcohols are also supplied commercially
[CAS #: 93821-11-5 or 68526-85-2].
1-Tridecanol
[0165] 1-Tridecanol, i.e. n-tridecanol [CAS #: 112-70-9;
C.sub.13H.sub.28O; M.sub.w=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 C.sub.10-C.sub.17
alcohols also comprising the C.sub.1-3 alcohols under the "Neodol
25" name from Shell. Another possible preparation is the reduction
of tridecanoic acid [CAS #: 638-53-9; C.sub.13H.sub.26O.sub.2;
M.sub.w=214.3], which is found in some vegetable oils, for example
in the seeds of the Australian plant Stackhousia tryonii).
Isotridecanol
[0166] Isotridecanol, i.e. 11-methyldodecanol [CAS #: 27458-92-0;
C.sub.13H.sub.28O; M.sub.w=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.degree. C.
Isotridecanol is sold commercially, for example by Exxon under the
EXXAL13 product name.
1-Tetradecanol
[0167] 1-Tetradecanol or myristyl alcohol [CAS #: 112-72-1;
C.sub.14H.sub.30O; M.sub.w=214.4], also defined in a technical
commercial context as a mixture of straight-chain and 100% linear
C.sub.12-C.sub.16 alcohols with a content of >95% of C.sub.14
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
[0168] 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; C.sub.8H.sub.18O], decanol, dodecanol (lauryl
alcohol); tetradecanol (myristyl alcohol), hexadecanol [CAS #:
36653-82-4; C.sub.18H.sub.34O; M.sub.w=242.44; also called cetyl
alcohol] and/or octadecanol [CAS #: 112-92-5; C.sub.18H.sub.38O;
M.sub.w=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
[0169] Neopentyl glycol, i.e. 2,2-dimethyl-1,3-propanediol [CAS #:
126-30-7; C.sub.5H.sub.12O.sub.2; M.sub.w=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
[0170] 1,6-Hexanediol [CAS #: 629-11-8; C.sub.6H.sub.14O.sub.2;
M.sub.w=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.
[0171] It is also possible to prepare 1,6-hexanediol from glucitol
[CAS #: 50-70-4; C.sub.6H.sub.14O.sub.6; M.sub.w=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
[0172] 2,2,4-Trimethyl-1,3-pentanediol [CAS #: 144-19-4;
C.sub.8H.sub.18O.sub.2; M.sub.w=146.2] is commercially available
(Alfa Aesar, Hangzhou Dayang Chemical Co., Ltd.).
2-Butyl-2-ethyl-1,3-propanediol
[0173] 2-Butyl-2-ethyl-1,3-propanediol [CAS #: 115-84-4;
C.sub.9H.sub.20O.sub.2; M.sub.w 160.3] is likewise commercially
available (Sigma-Aldrich; Jinan Haohua Industry Co., Ltd.).
Further Dialcohols
[0174] 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
[0175] 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 (H.sub.2SO.sub.4), in
order to obtain sufficiently pure substances.
E) Preparation of Diesters on the Basis of Dicarboxylic Esters
[0176] 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.
[0177] 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.
TABLE-US-00001 Dicarboxylic acid Proportion Monoalcohol
Dicarboxylic acid of RRM Adipic acid Isodecanol ##STR00001## Ac:
26.3% Al: 73.7% Adipic acid 1-Tridecanol ##STR00002## Ac: 18.8% Al:
81.2% Adipic acid Isotridecanol ##STR00003## Ac: 18.8% Al: 81.2%
Adipic acid 1-Tetradecanol ##STR00004## Ac: 18% Al: 82% Azelaic
acid 1-Tridecanol ##STR00005## Ac: 26% Al: 74% Dodecanedioic acid
1-Nonanol ##STR00006## Ac: 40.0% Al: 60.0% Dodecanedioic acid
Isodecanol ##STR00007## Ac: 37.5% Al: 62.5% Dodecanedioic acid
Isotridecanol ##STR00008## Ac: 31.6% Al: 68.4% Dodecanedioic acid
1-Tridecanol ##STR00009## Ac: 31.6% Al: 68.4%
G) Preparation of Ester Oils on the Basis of Diol Esters
[0178] 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.
[0179] 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.
TABLE-US-00002 Diol/Mono- carboxylic Proportion acid Diol ester of
RRM 1,6-Hexanediol Isodecanoic acid ##STR00010## Ac: 23.1% Al:
76.9% 1,6-Hexanediol 1-Tridecanoic acid ##STR00011## Ac: 18.8% Al:
81.2% 1,6-Hexanediol Isotridecanoic acid ##STR00012## Ac: 18.8% Al:
81.2% 1,6-Hexanediol Tetradecanoic acid ##STR00013## Ac: 18% Al:
82% 1,9-Nonanediol 1-Tridecanoic acid ##STR00014## Ac: 26% Al: 74%
1,12-Dodecane- diol Pelargonic acid (nonanoic acid) ##STR00015##
Ac: 40.0% Al: 60.0% 1,12-Dodecane- diol Isodecanoic acid
##STR00016## Ac: 37.5% Al: 62.5% 1,12-Dodecane- diol Isotridecanoic
acid ##STR00017## Ac: 31.6% Al: 68.4% 1,12-Dodecane- diol
1-Tridecanoic acid ##STR00018## Ac: 31.6% Al: 68.4%
[0180] The above-described diesters are merely examples which can
be modified in the context of the invention.
[0181] 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, C.sub.7H.sub.12O.sub.4; M.sub.w=160.2],
2,2,3-trimethyladipic acid [CAS #: 28472-18-6;
C.sub.9H.sub.16O.sub.4; M.sub.w=188.2], 2,2,4-trimethyladipic acid
[CAS #: 3586-39-8; C.sub.9H.sub.16O.sub.4; M.sub.w=188.2] and/or
2,4,4-trimethyladipic acid [CAS #: 3937-59-5;
C.sub.9H.sub.16O.sub.4; M.sub.w=188.2]. It is thus possible to
lower the pour points and slightly increase the viscosity level
compared to the unbranched variants.
[0182] 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
[0183] 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-US-00003 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
[0184] 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. .THETA..sub.40.degree. 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-US-00004 TABLE 2 Flash- NOACK Pour .eta..sub.40.degree. C.
.eta..sub.100.degree. C. OECD 301 Base oil point [.degree. C.] [%]
VI point [.degree. C.] [mm.sup.2/s] [mm.sup.2/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
[0185] 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).
[0186] 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.sub.-25.degree. C. [mPas]" and
"CCS.sub.-20.degree. C. [mPas]" columns each contain figures for
the "Cold Crank Simulator" according to the standard ASTM D5293 at
-25.degree. C. and -20.degree. C. The HTHS.sub.150.degree. C.
[mPas] column indicates what is called the "High-Temperature
High-Shear Viscosity" (HTHS) at elevated temperature.
TABLE-US-00005 TABLE 3 Density Flash- NOACK Pour
CCS.sub.-25.degree. C. CCS.sub.-20.degree. C. .eta..sub.40.degree.
C. .eta..sub.100.degree. C. .eta..sub.150.degree. C.
HTHS.sub.150.degree. C. Lubricant [g/cm.sup.3] point [.degree. C.]
[%] VI point [.degree. C.] [mPas] [mPas] [mm.sup.2/s] [mm.sup.2/s]
[mmVs] [mPas] C12D13 0.9051 276 2.4 158 -48 3210 1910 40.47 7.573
3.453 2700 (1.sup.st sample) C12D13 0.9020 277 4.3 147 -57 1700
42.0 7.5 (2.sup.nd sample) C12D13 0.904 261 2.9 156 -51 3230 41.2
7.6 (3.sup.rd sample) C10D13 2.7 172 -52 35.5 7.2 (4.sup.th sample)
C10D13 250 4 150 -50 36.0 6.8 (5.sup.th sample) C10D13 3.4 149 35.7
6.7 (6.sup.th sample) C9D13 3.5 150 36.1 6.8 (7.sup.th sample)
D5C18 280 2.0 146 -44 46.0 8.0 (8.sup.th 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
[0187] 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-US-00006 TABLE 4 Aquatic toxicity [mg/l] OECD 301 OECD OECD
OECD UBA Lubricant B/F [%] 201 202 203 # C12D13 4203 (1.sup.st
sample) C12D13 76/93 880 >1000 4203 (2.sup.nd sample) D5C18 85
>1000 >1000 >10 000 (8.sup.th sample) DITA 87 >1000
>100 2362 TMP-C8/10 64-88 140 600 >10 000 5371 PANOLIN 67-90
HLP Synth
[0188] In Table 3, a noticeable feature which is especially
positive is that the NOACK vaporization (physical vaporization
according to Noack, i.e. at 250.degree. 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.
[0189] 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.
[0190] Another advantage of the esters examined is the high
flashpoint of up to 280.degree. C., which is about 40.degree. 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.
[0191] 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.degree. 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.
[0192] 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.
[0193] Overall, the esters examined exhibit higher viscosity
indices, raised viscosity levels, increased flashpoints, and also
lower NOACK vaporizations compared to diisotridecyl adipate
(DITA).
[0194] 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).
[0195] The tests were conducted according to standard ASTM D7421-08
(fretting load) at a typical operating temperature for hydraulic
oils of +80.degree. 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 P.sub.0mean=3938 MPa are achieved, since there is
still no occurrence of adhesive failure at 2000 N or after 40
minutes.
[0196] 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.
[0197] FIG. 2a shows diagrams which illustrate the coefficient of
friction (f) and the standard force (F.sub.N) (top) and the stroke
(dx) and the standard force (F.sub.N) (bottom) of diisotridecyl
adipate in the positive x direction as a function of time.
[0198] FIG. 2b correspondingly shows diagrams which describe the
coefficient of friction (f) and the standard force (F.sub.N) (top)
and also the stroke (dx) and the standard force (F.sub.N) (bottom)
of diisotridecyl adipate in the negative x direction as a function
of time.
[0199] 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).
[0200] 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.
[0201] 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).
[0202] 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.
* * * * *