Note: Descriptions are shown in the official language in which they were submitted.
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OXIDATIVE STABLE OIL FORMULATION
Field of invention
The invention is related to an oxidation stable oil
formulation comprising a base oil composition and
additives.
Background of the invention
US-A-6790386 describes a dielectric fluid comprising
an iso-paraffin base oil and additives. The iso-paraffin
base oil is prepared by hydrotreating, hydroisomerisation
and hydrogenation of a paraffinic vacuum feedstock.
US-A-6214776 describes a formulation comprising a
paraffinic base oil and an additive package containing a
hindered phenol antioxidant and a metal deactivator, for
use as load tap changer or transformer oil. According to
this publication, base oils having a kinematic viscosity
at 40 C of between 5 and 20 cSt can be used as base oil
in formulations such as electrical oils or transformer
oils.
US-A-5241003 discloses a combination of a sulfur-
containing antiwear additive and a carboxylic derivative
dispersant for use as additive package for lubricants.
US-A-5773391 describes a composition comprising a
polyol ester base oil, an aliphatic monocarboxylic acid
mixture, and an additive package comprising an
antioxidant and a metal deactivator. The document further
discloses phosphorodithionates as antiwear additives.
WO-A-02070629 describes a process to make iso-
paraffinic base oils from a wax as made in a Fischer-
Tropsch process. According to this publication base
oils having a kinematic viscosity at 100 C of between 2
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and 9 cSt can be used as base oil in formulations such as
electrical oils or transformer oils.
US-A-5912212 describes oxidative stable oil
lubricating formulations consisting of a hydrocracked
paraffinic mineral base oil and 0.1 to 5 wto of a sulphur
or phosphorus containing compound. In the examples a
formulation consisting of a base oil and 3-methyl-5-tert-
butyl-4-hydroxy propionic acid ester, dioctylamino-
methyltolyltriazole and 0.4 wt% of dilaurylthio-
dipropionate. The oil had a high oxidative stability.
A demand is acknowledged for high oxidation resistant
oil products for use as for example electrical oil, in
particular as a transformer oil or a switch gear oil,
preferably without high additive treat rates due to
adverse effects on other properties than oxidation
stability.
Summary of the invention
This aim is achieved with the following oil
formulation. Oxidation stable oil formulation comprising
a base oil composition comprising a mineral-derived
naphthenic base oil, a mineral-derived paraffinic base
oil, and/or a Fischer-Tropsch derived base oil, a copper
passivator and of from 0.001 to less than 0.1 wt% of an
organic sulphur or phosphorus based compound.
Applicants found that an oil formulation is achieved
having a very high oxidation stability, however not
requiring a high treat rate.
Brief description of the drawings
Figure 1 and 2 represent the carbon distribution of
two Fischer-Tropsch derived base oils as used in the
examples.
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Detailed description of the invention
Applicants found that when a mineral-derived base oil
of the so-called paraffinic type or naphthenic type,
and/or a Fischer-Tropsch derived base oil is combined
with at least one copper passivator and a low content of
an anti-wear additive, an oil product is obtained which
has properties highly suitable for use as an electrical
oil. It was not to be expected that the combination of
the copper passivator and a small amount of an anti-wear
additive would result in such an improvement in oxidative
stability. A mineral-derived base oil has the meaning
within the context of this specification that the base
oil was obtained from a mineral oil source, while a
Fischer-Tropsch derived base oil was derived from
Fischer-Tropsch synthesis products.
Organic sulphur or phosphorus based compounds
preferably are sulphur and phosphorus containing
compounds such as sulfides, phosphides, dithiophopsphates
and dithiocarbamates. More preferably, sulphur and
phosphorus containing compounds are used which are known
to be used as an anti-wear additive in lubricating oil
formulations. Yet more preferably an organic polysulphide
compound is used. With polysulfide is here meant that the
organic compound comprises at least one group where two
sulphur atoms are directly linked. A preferred
polysulfide compound is a disulfide compound. Preferred
polysulfide compounds are represented by the formula (I)
Rl- (S) a-R2 (I)
wherein:
a is 2, 3, 4 or 5, preferably 2;
R1 and R2 may be the same or different and each may be
straight or branched alkyl group of 1 to 22 carbon atoms,
aryl groups of 6-20 carbon atoms, alkylaryl groups of
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7-20 carbon atoms or arylalkyl groups of 7-20 carbon
atoms. Preferred are arylalkyl groups, more preferred are
optionally substituted benzyl groups. More preferably R1
and R2 are independently selected from a benzyl group or
a straight or branched dodecyl group. Examples of
possible sulphur and phosphorus containing compounds and
the preferred compounds mentioned here are described in
the aforementioned US-A-5912212 as its component (b),
which publication is incorporated by reference. Examples
of suitable disulfide compounds are dibenzyldi-
sulfide,ditertdodecyldisulfide and didodecyldisulfide.
The content of the organic sulphur or phosphorus anti-
wear additive in the oil formulation is preferably less
than formulation 800 mg/kg and even more preferably less
than 400 mg/kg. The lower limit is preferably 1 mg/kg
more preferably 10 mg/kg, most preferably 50 mg/kg.
The copper passivator or electrostatic discharge
depressant, sometimes also referred as metal deactivator,
may be the typical copper passivator of which
N-salicylideneethylamine, N,N'-di salicylideneethyl-
diamine, triethylenediamine, ethylenediamminetetraacetic
acid, phosphoric acid, citric acid and gluconic acid.
More preferred are lecithin, thiadiazole, imidazole and
pyrazole and derivates thereof. Even more preferred are
zinc dialkyldithiophosphates, dialkyldithiocarbamates and
benzotriazoles and their tetrahydroderivates. Most
preferred are the compounds according to formula (II) or
even more preferred the optionally substituted
benzotriazole compound represented by the formula (III)
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C4tt- N
(II)
~ c N
(III)
wherein R4 may be hydrogen or a group represented by the
formula (IV)
~.~
(IV)
or by the formula (V)
(V)
wherein:
5 c is 0, 1, 2 or 3;
R3 is a straight or branched C1-4 alkyl group. Preferably
R3 is methyl or ethyl and C is 1 or 2. R5 is a methylene
or ethylene group; R6 and R7 are hydrogen or the same or
different straight or branched alkyl groups of 1-18
carbon atoms, preferably a branched alkyl group of 1-12
carbon atoms; R8 and R9 are the same or different alkyl
groups of 3-15 carbon atoms, preferably of 4-9 carbon
atoms.
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Preferred compounds are 1-[bis(2-ethylhexyl)-
aminomethyl]benzotriazole, methylbenzotriazole,
dimethylbenzotriazole, ethylbenzotriazole,
ethylmethylbenzotriazole, diethylbenzotriazole and
mixtures thereof. Other preferred compounds include (N-
Bis(2-ethylhexyl)-aminomethyl-tolutriazole, non-
substituted benzotriazole, and 5-methyl-lH-benzotriazole.
Examples of copper passivator additives as described
above are described in US-A-5912212, EP-A-1054052 and in
US-A-2002/0109127, which publications are hereby
incorporated by reference. These benzotriazoles compounds
are preferred because they also act as an electrostatic
discharge depressant, which is beneficial when the oil
formulation is used as an electrical oil. Copper
passivator additives as those described above are
commercially available under the product names BTA, TTA,
IRGAMET 39, IRGAMET30 and IRGAMET 38S from CIBA Ltd Basel
Switzerland, also traded under the trade name Reomet by
CIBA.
The content of the above copper passivator in the oil
formulation is preferably above 1 mg/kg and more
preferably above 5 mg/kg. A practical upper limit may
vary depending on the specific application of the oil
formulation. For example, when desiring improved
dielectric discharge tendencies of the oil for use as
electrical oil it may be desired to add a high
concentration of the copper passivator additive. This
concentration may be up to 3 wt%, preferably however in
the range of from 0.001 to 1 wto. Applicants found that
the advantages of the invention can be achieved at
concentrations below 1000 mg/kg and more preferably below
300 mg/kg, even more preferably below 50 mg/kg.
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The oil formulation preferably also comprises an
anti-oxidant additive. It has been found that, especially
in case the base oil is a mineral paraffinic base oil or
a Fischer-Tropsch derived base oil, the sludge formed and
total acidity both measured after the IEC 61125 C
oxidation test, which properties are indicators for good
oxidation stable oils, are considerably reduced when also
an anti-oxidant is present. The anti-oxidant may be a so-
called hindered phenolic or amine antioxidant, for
example naphthols, sterically hindered monohydric,
dihydric and trihydric phenols, sterically hindered
dinuclear, trinuclear and polynuclear phenols, alkylated
or styrenated diphenylamines or ionol derived hindered
phenols. Sterically hindered phenolic antioxidants of
particular interest are selected from the group
consisting of 2,6-di-tert-butylphenol (IRGANOX TM L 140,
CIBA), di tert-butylated hydroxotoluene (BHT), methylene-
4,4'-bis-(2.6-tert-butylphenol), 2,2'-methylene bis-(4,6-
di-tert-butylphenol), 1,6-hexamethylene-bis-(3,5-di-tert-
butyl-hydroxyhydrocinnamate) (IRGANOX TM L109, CIBA),
((3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)methyl)thio)
acetic acid, C10-C14isoalkyl esters (IRGANOX TM L118,
CIBA), 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid, C7-
C9alkyl esters (IRGANOX TM L135, CIBA,) tetrakis-(3-(3,5-
di-tert-butyl-4-hydroxyphenyl)-propionyloxymethyl)methane
(IRGANOX TM 1010, CIBA), thiodiethylene bis(3,5-di-tert-
butyl-4-hydroxyhydrocinnamate (IRGANOX TM 1035, CIBA),
octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate
(IRGANOX TM 1076, CIBA) and 2,5-di-tert-
butylhydroquinone. These products are known and are
commercially available. Of most particular interest is
3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid-C7-C9-
alkyl ester.
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Examples of amine antioxidants are aromatic amine
anti-oxidants for example N,N'-Di-isopropyl-p-
phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine,
N,N'-bis(1,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-
bis(l-ethyl-3-methyl-pentyl)-p-phenylene-diamine, N,N'-
bis(1-methyl-heptyl)-p-phenylenediamine, N,N'-
dicyclohexyl-p-phenylene-diamine, N,N'-diphenyl-p-
phenylenediamine, N,N'-di(naphthyl-2-)-p-
phenylenediamine, N-isopropyl-N'-phenyl-p-
phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-
phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-
phenylenediamine, N'-cyclohexyl-N'-phenyl-p-
phenylenediamine, 4-(p-toluene-sulfoamido)diphenylamine,
N,N'-dimethyl-N,N'-di-sec-butyl-p-phenylenediamine,
diphenylamine, N-allyldiphenylamine, 4-isopropoxy-
diphenylamine, N-phenyl-l-naphthylamine, N-phenyl-2-
naphthylamine, octylated diphenylamine, e.g. p,p'-di-
tert-octyldiphenylamine, 4-n-butylaminophenol,
4-butyrylaminophenol, 4-nonanoylaminophenol,
4-dodecanoylaminophenol, 4-octadecanoylaminophenol, di(4-
methoxyphenyl)amine, 2,6-di-tert-butyl-4-dimethyl-
aminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-
diaminodiphenylmethane, N,N,N',N'-tetramethyl-4,4'-
diaminodiphenylmethane, 1,2-di(phenylamino)ethane,
1,2-di[(2-methylphenyl)amino]ethane, 1,3-di-
(phenylamino)propane, (o-tolyl)biguanide, di[4-(1',3'-
dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-l-
naphthylamine, mixture of mono- and dialkylated tert-
butyl-/tert-octyldiphenylamines, 2,3-dihydro-3,3-
dimethyl-4H-1,4-benzothiazine, phenothiazine,
N-allylphenothiazine, tert-octylated phenothiazine,
3,7-di-tert-octylphenothiazine. Also possible amine
antioxidants are those according to formula VIII and IX
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of EP-A-1054052, which compounds are also described in
US-A-4,824,601, which publications are hereby
incorporated by reference.
The content of the anti oxidant additive is
preferably less than 2 wt% and more preferably less than
1 wto. The content is preferably less than 0,6 wta in
certain applications, such as when the oil formulation is
used as an electrical oil. The content of antioxidant is
preferably greater than 10 mg/kg.
The oil formulation preferably has a sulphur content
of below 0,5 wt% and even more preferably below 0,15 wt%.
The source of the majority of the sulphur in the oil
formulation will be the sulphur as contained in the base
oil component of the oil formulation according the
invention.
The base oil composition preferably has a kinematic
viscosity at 100 C of less than 50 mm2/sec, more
preferably between 2 and 25 mm2/sec, most preferably
between 2 and 15 mm2/sec. The base oil composition
preferably has a kinematic viscosity at 40 C of between
1 and 200 mm2/sec, more preferably between 3.5 and 100
mm2/sec, most preferably between 5 and 12 mm2/sec. The
viscosity of the base oil composition will also depend on
the particular use of the oil formulation. If the oil
formulation is used as an electrical oil its kinematic
viscosity at 40 Cis preferably between 1 and 50 mm2/sec.
More preferably, if this electrical oil formulation is a
transformer oil, the base oil will preferably have a
kinematic viscosity at 40 C of between 5 and 15 mm2/sec.
If the electrical oil is a low temperature switch gear
oil the base oil viscosity at 40 C is preferably between
1 and 15 and more preferably between 1 and 4 mm2/sec.
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The flash point of the base oil composition as
measured by ASTM D92 may be greater than 90 C,
preferably greater than 120 C, yet more preferably
greater than 140 C, and even more preferably greater
5 than 170 C. The higher flash points are desirable for
applications where peak temperatures can exceed the
average oil temperature, for instance in applications
under high temperature and/or with restricted heat
transmission potential. Examples are electric
10 transformers and electric engines.
The base oil composition may comprise one or more
base oils selected from mineral-derived naphthenic base
oils, mineral-derived paraffic base oils, or Fischer-
Tropsch derived base oils.
The base oil composition may this comprise a mineral-
derived base oil of the so-called paraffinic type or
naphthenic type. Such base oils are obtained by refinery
processes starting from paraffinic and naphthenic crude
feeds. Mineral-derived naphthenic base oils for the
purpose of this invention are defined as having a pour
point of below -20 C and a viscosity index of below 70.
Mineral-derived paraffin base oils are defined by a
viscosity index of greater than 70, preferably greater
than 90. Mineral-derived naphthenic and paraffin base
oils are well known and described in more detail in
"Lubricant base oil and wax processing", Avilino
Sequeira, Jr., Marcel Dekker, Inc, New York, 1994, ISBN
0-8247-9256-4, pages 28-35.
Applicants found that very good oxidative stable oil
formulations can be obtained when the base oil
composition has a saturates content as measured by IP386
of preferably greater than 98 wt%, more preferably
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greater than 99 wt% and even more preferably greater than
99.5 wt% as measured on fresh base oil.
The base oil composition preferably comprises a base
oil comprising a series of iso-paraffins having n, n+l,
n+2, n+3 and n+4 carbon atoms and wherein n is a number
between 20 and 35.
Preferably, the paraffin content in the base oil
composition is greater than 80 wt%, more preferably
greater than 90 wt%, yet more preferably greater than
95%, and again more preferably greater than 98%.
The base oil composition furthermore may preferably
have a content of naphthenic compounds of between 1 and
wto. It has been found that these base oils have a
good additive response to the additives listed above when
15 aiming to improve oxidation stability. The content of
naphthenic compounds and the presence of such a
continuous series of iso-paraffins may be measured by
Field desorption/Field Ionisation (FD/FI) technique. In
this technique the oil sample is first separated into a
20 polar (aromatic) phase and a non-polar (saturates) phase
by making use of a high performance liquid chromatography
(HPLC) method IP368/01, wherein as mobile phase pentane
is used instead of hexane as the method states. The
saturates and aromatic fractions are then analyzed using
a Finnigan MAT90 mass spectrometer equipped with a Field
desorption/Field Ionisation (FD/FI) interface, wherein FI
(a "soft" ionisation technique) is used for the
determination of hydrocarbon types in terms of carbon
number and hydrogen deficiency. The type classification
of compounds in mass spectrometry is determined by the
characteristic ions formed and is normally classified by
"z number". This is given by the general formula for all
hydrocarbon species: CnH2n+z= Because the saturates phase
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is analysed separately from the aromatic phase it is
possible to determine the content of the different iso-
paraffins having the same stoichiometry or n-number. The
results of the mass spectrometer are processed using
commercial software (poly 32; available from Sierra
Analytics LLC, 3453 Dragoo Park Drive, Modesto,
California GA95350 USA) to determine the relative
proportions of each hydrocarbon type.
The base oil composition having the continuous iso-
paraffinic series as described above are preferably
obtained by hydroisomerisation of a paraffinic wax, yet
more preferably followed by some type of dewaxing, such
as solvent or catalytic dewaxing.
The above described base oil composition may
preferably be obtained by hydroisomerisation of a
paraffinic wax, preferably followed by a dewaxing
treatment, such as a solvent or catalytic dewaxing
treatment. The paraffinic wax may be a highly paraffinic
slack wax. More preferably the paraffinic wax is a
Fischer-Tropsch derived wax, because of its purity and
even higher paraffinic content.
The base oils as derived from a Fischer-Tropsch wax
as here described will be referred to in this description
as Fischer-Tropsch derived base oils.
Examples of Fischer-Tropsch processes which for
example can be used to prepare the above-described
Fischer-Tropsch derived base oil are the so-called
commercial Slurry Phase Distillate technology of Sasol,
the Shell Middle Distillate Synthesis Process and the
"AGC-21" Exxon Mobil process. These and other processes
are for example described in more detail in EP-A-776959,
EP-A-668342, US-A-4943672, US-A-5059299, WO-A-9934917 and
WO-A-9920720. Typically these Fischer-Tropsch synthesis
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products will comprise hydrocarbons having 1 to 100 and
even more than 100 carbon atoms. This hydrocarbon product
will comprise normal paraffins, iso-paraffins, oxygenated
products and unsaturated products. If base oils are one
of the desired iso-paraffinic products it may be
advantageous to use a relatively heavy Fischer-Tropsch
derived feed. The relatively heavy Fischer-Tropsch
derived feed has at least 30 wto, preferably at least
50 wto, and more preferably at least 55 wt% of compounds
having at least 30 carbon atoms. Furthermore the weight
ratio of compounds having at least 60 or more carbon
atoms and compounds having at least 30 carbon atoms of
the Fischer-Tropsch derived feed is preferably at least
0.2, more preferably at least 0.4 and most preferably at
least 0.55. Preferably the Fischer-Tropsch derived feed
comprises a C20+ fraction having an ASF-alpha value
(Anderson-Schulz-Flory chain growth factor) of at least
0.925, preferably at least 0.935, more preferably at
least 0.945, even more preferably at least 0.955. Such a
Fischer-Tropsch derived feed can be obtained by any
process, which yields a relatively heavy Fischer-Tropsch
product as described above. Not all Fischer-Tropsch
processes yield such a heavy product. An example of a
suitable Fischer-Tropsch process is described in
WO-A-9934917.
The Fischer-Tropsch derived product will contain no
or very little sulphur and nitrogen containing compounds.
This is typical for a product derived from a Fischer-
Tropsch reaction, which uses synthesis gas containing
almost no impurities. Sulphur and nitrogen levels will
generally be below the detection limits, which are
currently 5 mg/kg for sulphur and 1 mg/kg for nitrogen
respectively.
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The process will generally comprise a Fischer-Tropsch
synthesis, a hydroisomerisation step and an optional pour
point reducing step, wherein said hydroisomerisation step
and optional pour point reducing step are performed as:
(a) hydrocracking/hydroisomerisating a Fischer-Tropsch
product,
(b) separating the product of step (a) into at least one
or more distillate fuel fractions and a base oil or base
oil intermediate fraction.
If the viscosity and pour point of the base oil as
obtained in step (b) is as desired no further processing
is necessary and the oil can be used as the base oil
according the invention. If required, the pour point of
the base oil intermediate fraction is suitably further
reduced in a step (c) by means of solvent or preferably
catalytic dewaxing of the oil obtained in step (b) to
obtain oil having the preferred low pour point. The
desired viscosity of the base oil may be obtained by
isolating by means of distillation from the intermediate
base oil fraction or from the dewaxed oil the a suitable
boiling range product corresponding with the desired
viscosity. Distillation may be suitably a vacuum
distillation step.
The hydroconversion/hydroisomerisation reaction of
step (a) is preferably performed in the presence of
hydrogen and a catalyst, which catalyst can be chosen
from those known to one skilled in the art as being
suitable for this reaction of which some will be
described in more detail below. The catalyst may in
principle be any catalyst known in the art to be suitable
for isomerising paraffinic molecules. In general,
suitable hydroconversion/hydroisomerisation catalysts are
those comprising a hydrogenation component supported on a
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refractory oxide carrier, such as amorphous silica-
alumina (ASA), alumina, fluorided alumina, molecular
sieves (zeolites) or mixtures of two or more of these.
One type of preferred catalysts to be applied in the
5 hydroconversion/hydroisomerisation step in accordance
with the present invention are hydroconversion/
hydroisomerisation catalysts comprising platinum and/or
palladium as the hydrogenation component. A very much
preferred hydroconversion/hydroisomerisation catalyst
10 comprises platinum and palladium supported on an
amorphous silica-alumina (ASA) carrier. The platinum
and/or palladium is suitably present in an amount of from
0.1 to 5.0% by weight, more suitably from 0.2 to 2.0% by
weight, calculated as element and based on total weight
15 of carrier. If both present, the weight ratio of platinum
to palladium may vary within wide limits, but suitably is
in the range of from 0.05 to 10, more suitably 0.1 to 5.
Examples of suitable noble metal on ASA catalysts are,
for instance, disclosed in WO-A-9410264 and EP-A-0582347.
Other suitable noble metal-based catalysts, such as
platinum on a fluorided alumina carrier, are disclosed in
e.g. US-A-5059299 and WO-A-9220759.
A second type of suitable hydroconversion/
hydroisomerisation catalysts are those comprising at
least one Group VIB metal, preferably tungsten and/or
molybdenum, and at least one non-noble Group VIII metal,
preferably nickel and/or cobalt, as the hydrogenation
component. Both metals may be present as oxides,
sulphides or a combination thereof. The Group VIB metal
is suitably present in an amount of from 1 to 35% by
weight, more suitably from 5 to 30% by weight, calculated
as element and based on total weight of the carrier. The
non-noble Group VIII metal is suitably present in an
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amount of from 1 to 25 wto, preferably 2 to 15 wto,
calculated as element and based on total weight of
carrier. A hydroconversion catalyst of this type, which
has been found particularly suitable, is a catalyst
comprising nickel and tungsten supported on fluorided
alumina.
The above non-noble metal-based catalysts are
preferably used in their sulphided form. In order to
maintain the sulphided form of the catalyst during use
some sulphur needs to be present in the feed. Preferably
at least 10 mg/kg and more preferably between 50 and
150 mg/kg of sulphur is present in the feed.
A preferred catalyst, which can be used in a non-
sulphided form, comprises a non-noble Group VIII metal,
e.g., iron, nickel, in conjunction with a Group IB metal,
e.g., copper, supported on an acidic support. Copper is
preferably present to suppress hydrogenolysis of
paraffins to methane. The catalyst has a pore volume
preferably in the range of 0.35 to 1.10 ml/g as
determined by water absorption, a surface area of
preferably between 200-500 m2/g as determined by BET
nitrogen adsorption, and a bulk density of between
0.4-1.0 g/ml. The catalyst support is preferably made of
an amorphous silica-alumina wherein the alumina may be
present within wide range of between 5 and 96 wt%,
preferably between 20 and 85 wto. The silica content as
Si02 is preferably between 15 and 80 wt%. Also, the
support may contain small amounts, e.g., 20-30 wto, of a
binder, e.g., alumina, silica, Group IVA metal oxides,
and various types of clays, magnesia, etc., preferably
alumina or silica.
The preparation of amorphous silica-alumina
microspheres has been described in Ryland, Lloyd B.,
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Tamele, M.W., and Wilson, J.N., Cracking Catalysts,
Catalysis: volume VII, Ed. Paul H. Emmett, Reinhold
Publishing Corporation, New York, 1960, pp. 5-9.
The catalyst is prepared by co-impregnating the
metals from solutions onto the support, drying at
100-150 C, and calcining in air at 200-550 C. The
Group VIII metal is present in amounts of about 15 wt% or
less, preferably 1-12 wt%, while the Group IB metal is
usually present in lesser amounts, e.g., 1:2 to about
1:20 weight ratio respecting the Group VIII metal.
A typical catalyst is shown below:
Ni, wt% 2.5-3.5
Cu, wt% 0.25-0.35
A1203-Si02 wto 65-75
A1203 (binder) wto 25-30
Surface Area 290-325 m2/g
Pore Volume (Hg) 0.35-0.45 ml/g
Bulk Density 0.58-0.68 g/ml
Another class of suitable hydroconversion/
hydroisomerisation catalysts are those based on zeolitic
materials, suitably comprising at least one Group VIII
metal component, preferably Pt and/or Pd, as the
hydrogenation component. Suitable zeolitic and other
aluminosilicate materials, then, include Zeolite beta,
Zeolite Y, Ultra Stable Y, ZSM-5, ZSM-12, ZSM-22, ZSM-23,
ZSM-48, MCM-68, ZSM-35, SSZ-32, ferrierite, mordenite and
silica-aluminophosphates, such as SAPO-11 and SAPO-31.
Examples of suitable hydroisomerisation/
hydroisomerisation catalysts are, for instance, described
in WO-A-9201657. Combinations of these catalysts are also
possible. Very suitable hydroconversion/
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
18
hydroisomerisation processes are those involving a first
step wherein a zeolite beta or ZSM-48 based catalyst is
used and a second step wherein a ZSM-5, ZSM-12, ZSM-22,
ZSM-23, ZSM-48, MCM-68, ZSM-35, SSZ-32, ferrierite,
mordenite based catalyst is used. Of the latter group
ZSM-23, ZSM-22 and ZSM-48 are preferred. Examples of such
processes are described in US-A-20040065581, which
disclose a process comprising a first step catalyst
comprising platinum and zeolite beta and a second step
catalyst comprising platinum and ZSM-48.
Combinations wherein the Fischer-Tropsch product is
first subjected to a first hydroisomerisation step using
the amorphous catalyst comprising a silica-alumina
carrier as described above followed by a second
hydroisomerisation step using the catalyst comprising the
molecular sieve has also been identified as a preferred
process to prepare the base oil to be used in the present
invention. More preferred the first and second
hydroisomerisation steps are performed in series flow.
Most preferred these two steps are performed in a single
reactor comprising beds of the above amorphous and/or
crystalline catalysts.
In step (a) the feed is contacted with hydrogen in
the presence of the catalyst at elevated temperature and
pressure. The temperatures typically will be in the range
of from 175 to 380 C, preferably higher than 250 C and
more preferably from 300 to 370 C. The pressure will
typically be in the range of from 10 to 250 bar and
preferably between 20 and 80 bar. Hydrogen may be
supplied at a gas hourly space velocity of from 100 to
10000 Nl/1/hr, preferably from 500 to 5000 N1/1/hr. The
hydrocarbon feed may be provided at a weight hourly space
velocity of from 0.1 to 5 kg/1/hr, preferably higher than
CA 02611649 2007-12-10
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19
0.5 kg/1/hr and more preferably lower than 2 kg/1/hr. The
ratio of hydrogen to hydrocarbon feed may range from 100
to 5000 Nl/kg and is preferably from 250 to 2500 N1/kg.
The conversion in step (a) as defined as the weight
percentage of the feed boiling above 370 C which reacts
per pass to a fraction boiling below 370 C, is at least
20 wt%, preferably at least 25 wt%, but preferably not
more than 80 wt%, more preferably not more than 65 wt%.
The feed as used above in the definition is the total
hydrocarbon feed fed to step (a), thus also any optional
recycle of a high boiling fraction which may be obtained
in step (b).
In step (b) the product of step (a) is preferably
separated into one or more distillate fuels fractions and
a base oil or base oil precursor fraction having the
desired viscosity properties. If the pour point is not in
the desired range the pour point of the base oil is
further reduced by means of a dewaxing step (c),
preferably by catalytic dewaxing. In such an embodiment
it may be a further advantage to dewax a wider boiling
fraction of the product of step (a). From the resulting
dewaxed product the base oil and oils having a desired
viscosity can then be advantageously isolated by means of
distillation. Dewaxing is preferably performed by
catalytic dewaxing as for example described in
WO-A-02070629, which publication is hereby incorporated
by reference. The final boiling point of the feed to the
dewaxing step (c) may be the final boiling point of the
product of step (a) or lower if desired.
The oil formulation may comprise a single type of
base oil or blends of the above-described base oils as
base oil composition. Preferably, the present invention
further relates to formulations wherein the base oil
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
composition comprises at least 80% by weight of the total
formulation of a mineral-derived naphthenic base oil; to
formulations wherein the base oil comprises at least 80%
by weight of a mineral-derived paraffinic base oil; and
5 to formulations wherein the base oil composition
comprises at least 80% by weight of a Fischer-Tropsch
derived base oil.
Also further base oils and other synthetic base oil
components may be present in the oil formulation, such as
10 for example esters, poly alpha olefins, as preferably
obtained by oligomerisation of an olefinic compound, poly
alkylene glycols and the like. Possible base oil
compositions preferably include mineral-derived
paraffinic base oils and Fischer-Tropsch derived base
15 oils, mineral-derived naphthenic base oils and Fischer-
Tropsch derived base oils, and mixtures of the three base
oil components.
However, it has been found especially advantageous to
use a Fischer-Tropsch derived base oil as the
20 substantially the sole base oil component. With
substantially is here meant that more than 80 wt%, more
preferably more than 90 wt% and most preferably 100 wt%
of the base oil component in the oil formulation is a
Fischer-Tropsch derived base oil as described in detail
above.
Additional additives next to the ones described above
may also be present in the formulation. The type of
additives will depend on the specific application.
Without intending to be limiting, examples of possible
additives are dispersants, detergents, viscosity
modifying polymers, hydrocarbon or oxygenated hydrocarbon
type pour point depressants, emulsifiers, demulsifiers,
antistaining additives and friction modifiers. Specific
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21
examples of such additives are described in for example
Kirk-Othmer Encyclopedia of Chemical Technology, third
edition, volume 14, pages 477-526. Suitably the
dispersant is an ashless dispersant, for example
polybutylene succinimide polyamines or Mannic base type
dispersants. Suitably the detergent is an over-based
metallic detergent, for example the phosphonate,
sulfonate, phenolate or salicylate types as described in
the above referred to General Textbook. Suitably the
viscosity modifier is a viscosity modifying polymer, for
example polyisobutylenes, olefin copolymers, poly-
methacrylates and polyalkylstyrenes and hydrogenated
polyisoprene star polymer (Shellvis). Examples of
suitable antifoaming agents are polydimethylsiloxanes and
polyethylene glycol ethers and esters.
The oil formulation may find use as turbine oil,
gasoline engine oil, diesel engine oil, automotive and
industrial gear oils, for example automatic and manual
transmission and differential oils, hydraulic machine
oil, refrigerator oil, plastic processing oil for
rolling, press, forging, sqeezing, draw, punch and the
like operations, thermal treating oil, discharge
processing oil, slide guide oil, rust proofing oil and
heat medium. A preferred use of the oil formulation is as
electrical oil. It has further been found that when the
base oil component of the oil formulation comprises
substantially of the Fischer-Tropsch derived base oil an
electrical oil formulation is obtained which has good
oxidative stability, as expressed by low acid formation
and/or low sludge formation and also excellent low
temperature viscosity values. Examples of applications
are switch gears, transformers, regulators, circuit
breakers, power plant reactors, cables and other
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22
electrical equipment. A problem often encountered when
using an electrical oil based on a naphthenic base oil is
that the kinematic viscosity at -30 C is too high. When
such an oil would be used in application which have to
start up at low temperatures, especially at temperatures
below 0 C, the higher viscosity will have a negative
effect on the required heat dissipation of the electrical
oil. Overheating of the equipment can result. Applicants
have found that when a Fischer-Tropsch base oil having a
kinematic viscosity at 40 C of between 1 and 15 mm2/sec
and a pour point of below -30 C, more preferably below
-40 C an electrical oil can be obtained having the above
desired properties.
In order to improve the gassing tendency of the oil
formulation it is preferred to add between 0.05 and
10 wt%, preferably between 0.1 and 5 wt% of an aromatic
compound. Preferred aromatic compounds are for example
tertrahydronaphthalene, diethylbenzene, di-
isopropylbenzene, a mixture of alkylbenzenes as
commercially obtainable as "Shell Oil 4697" or "Shellsol
A 150" both "Shell" products obtainable from Shell
Deutschland GmbH. Another preferred mixture of aromatic
compounds is comprised in a mixture of 2,6-di-t-butyl
phenol and 2,6-di-t-butyl cresol. Preferably the oil
formulation comprises between 0.1 and 3 wto of 2,6-di-t-
butyl phenol and 0.1 to 2 wt% of 2,6-di-t-butyl cresol in
a weight ratio of between 1:1 and 1:1.5.
The oil formulation, preferably comprising the anti-
wear additive, is preferably subjected to an additional
clay treatment. Clay treatment is a well know treatment
to remove polar compounds from the oil formulation. It is
performed in order to further improve the color, chemical
and thermal stability of the oil formulation. It may be
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23
performed prior to adding the additives mentioned in this
description on a, partly, formulated oil formulation.
Clay treatment processes are for example described in
Lubricant base oil and wax processing, Avilino Sequeira,
Jr., Marcel Dekker, Inc, New York, 1994, ISBN 0-8247-
9256-4, pages 229-232. Preferably the copper passivator
and optional anti-oxidant are added after the clay
treatment.
The oil formulations comprising a Fischer-Tropsch
derived base oil as described above show a very low
dielectric dissipation factor, even after prolonged
testing at elevated temperature. The low dissipation
factor is indicative for a low loss of electric power in
the application wherein the electrical oil is used.
Because the dissipation factor does not significantly
increase over time, especially when compared to the
naphthenic based electrical oil formulations, a very
efficient application of the oil results.
The electrical oil as described above may find use in
applications which have to start up regularly, especially
more than 10 times per year at a temperature of below
0 C, more preferably below -5 C, wherein the
temperature of the oil when the application is running is
above 0 C. Examples of such applications are as low
temperature switch gear oils, transformers, regulators,
circuit breakers, power plant reactors, switch gear,
cables, electrical equipment. Such applications are well
known to the skilled person and described for example in
Lubricants and related products, Dieter Klamann, Verlag
Chemie GmbH, Weinhem, 1984, pages 330-339.
The invention will be illustrated with the following
non-limiting examples. In the examples use has been made
of four different types of base oils. One Fischer-Tropsch
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WO 2006/136591 PCT/EP2006/063433
24
derived base oil, referred to as GTL BO, two naphthenic
type of base oils, referred to as naphthenic-1 and
naphthenic-2, and a mineral paraffinic base oil. The
properties of these base oils are listed in Table 1.
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
U
.rq
4-I N M ~ M OD N
44 i [- M
~4
U
-H
rl
4-1 H N 0 co U1 l0
r-I
1 CO O ir-I W
r-I
N
rd
a
U
H ao o d
LIl V
J-~ N l-
.t;
fL
co
z
U
-ri
0) rl oD O O l-
V l0 d~ d~
J-i N 00
z
0 ao 0o d~ w w ~4 *
N r p a h H I N ri
H G+
N
0 O 1I1 O oD
r'1 tn N
r-I N
m
H
~
~
~
pUq ~ N u ~i N
r
N r ~-+ ~ ~ b)
a -a
H F1+
C7
~
U) U) tr)
~ ~ w X
U U
E E o 0 E
N Ln 0 0 r- ui N 0
r=
N M dl ~
Q A Q Q Q I~
M
K4
O
J1 ~ 0
o Ll 1:: =-I m N 4-)
ri O 0 -ri 0 S-: ~j :J
rl H 0 O 0 W -H t3' A
0 a
~ u
,~ wHG o
n o] M
t~ 0 rd S-i ~ U ~
H W x x H a Cz a Q 1~ U 'L3 PU
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
26
r-i un ai
N
O
tn
x: -a
U !-I
N
J-1 N
Lfl U
~ Lc4 4J
o \
p a Q N
N
0
rl N
J-1
O Lf)
0
O O ~i 04
0 E
H O
U
b
r-i U
U =rl
=ri ~',
Ga N
~ G ~
0 -0
p
ID, G
~4
0 bi
U) q
a) =r-1
'd ~+
=
d -i U
r-I 4-1
4) N N
=,~ S."
G4 1-) Ul
'0
~r O (.i='
O
a) E
~+ U) 0
q U
U1 =rl
t~ 4-I U
N 4-1 =rl
~ ?4 N
(0 CL
r-i 4 r-i 104
o ~ 0 4 ~ ('~.,
O l0 r= -1
o a 0 0 rn
v
.~
C rd 1+
0 r.
S~ flS M
t 0 N
U N =~
oW \o
N N d'
P4
1) II
tD M
rn o rn 0 u)
Ln u1 -ri i.1
,..i n q, N
x A N ~ 0 Ei
OH 4-) Cl ~
-H ~+ 0
ro U
td ~+ C: N 11 U
1~ ~ ~ A N C
bn ~+ b) ~ ?4 rt =~ ,~
~ R4 0 =~ 0 '~ U 0I ~
~ u~~i u aC~q N ~ * 3 ~
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
27
Example 1
In Example 1 two formulations A and B were prepared
of which the base oil component consisted of 95 wto of
the naphthenic-2 base oil and for 5 wt% of the
paraffinic-1 base oil. To these mixtures 10 mg/kg of
1-[bis(2-ethylhexyl)aminomethyl]benzotriazole (Reomet38S)
was added. To mixture A 200 mg/kg of Dibenzyldisulfide
was added and to mixture B 200 mg/kg of Di-n-
dodecyldisulfid was added. Oil mixtures A and B were
tested with the IEC 61125 C Oxidation test 164h/120 C
test to measure the acidity of the oil phase. The acidity
of the oil phase of mixture A was 0.26 mg KOH/g and the
acidity of the oil phase of mixture B was 0.94 mg KOH/g.
Both values are very low and illustrate an excellent
oxidative stability. The values for Mixture A show that
even more excellent results are obtained when the
preferred Dibenzyldisulfide additive is used as the an
organic polysulphide anti-wear additive. It is surprising
that the choice of a particular anti-wear additive can
improve the oxidation stability in the manner here
illustrated.
Example 2
Starting with the mineral-derived naphthenic-1,
mineral-derived paraffin base oil and the GTL base oil-1
of Table 1 five different oil mixtures according to the
additivation schemes 1-5 of table 2 were made. For all of
these oil mixtures the Sludge Formation was measured
according to the Oxidation Test IEC 61125 C at
164h/120 C. The lower the value the less sludge is found.
The results are also presented in Table 2.
From Table 2 it can be seen that the combination of
the organic polysulphide anti-wear additive and the
copper passivator result in a remarkable low sludge
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
28
formation. Especially for the mineral paraffin base oils
and the Fischer-Tropsch derived base oil the presence of
an anti-oxidant further reduces the sludge formation
significantly.
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
29
m Ln 0 1
Lfl O ~ O N ~ O
N O O~ O O~
r-I l0 r-I
O O o0 00 l-
O N O O
N ~
O O O
rI al frl
O l0 O cr
f7 O 1 l.fl N O
N
O O O
O O M
(Y) [M N
N I ~ I L(1 z:v O
r-i N O
O O lll
O dq 0o
rl I ~ ~ l- f'') 0
r-i M 0
-Y 14
U bi bi F~
o\0 Ul U~ C/~
N
rI
H
l4 W
M
W N
H E
0
a
rn
~ ~
-
~ 0
N
0 ~ (d ~
U -ri ~
U N r-i ~-I r-I r-i
(d E N 5C 0 0 0
0 U ~ cl r~ E-+ a) N
-rl Ul 4-I rl 4) x Ul U1 H
~ ~ .a ~ I
~ -~ -~ a) U U 0
4-I fd ~ N 4-1 L: L; N
N 'J >, " 4) -rl a) -rl En
-r-I (L) Q r' -ri .1a (d ~
'O Q -r-I 4-3 04 ~-I ~
H v~i ~ Q I rE d ~ a c~.7
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
For all of these oil mixtures according to
additivation schemes 1-5 of above also the Total Acidity
using the Oxidation Test IEC 61125 C at 164h/120 C was
measured. The lower the value the less acid compounds are
5 formed and the more oxidative stable the oil formulation
is. The results are presented in Table 3.
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WO 2006/136591 PCT/EP2006/063433
31
O 00 N N O
Ln O O O O O r-I
N , . . . .
O r-I O O
("1 00 c-
%4' O O m Ln
rI
N o c~ ~
rn 00 Ln
m O I Ln r- ~
N ~
U r m Ln
N ~ O i 00 L~ Ln
rI Lfl p
N M lfl H
rI
Ln w d~ rn ~
H O ~1 ~1 bl
" x x x
x x x
C\0
H ~
0 O
~ i U
U
0 41 4J
H
U (1) ro
U =
rA
0
U
=ri
-O ~ rl rl
Q) 0 ~ r-i ~
~ N ~ H 0 0
O
4-I U ro .c: E=+ a) (1)
Ul 4-I H x U2 Ul H
>4 r-i >1 a) x ~a ~ I
A-) r, J g, r-i ~ .Q r-i
-H 0 m 41 0 -u -~
'O -r1 -rl Q) N (y U U O
=H 4J 'O I (fS (d =ri =rl
U rd r-I N =ri 'o ~ 4)
N1 (~ ~> >i ~-1 =r-I ~ =r-I U~
-rl N Ul .0 x 4-I (t
a) r+ ~ Fz: -li 0 0 44 W
r-I fd -rl (1) A N -rI (d
IQ J-! 'o ~Q F-' -0 Q4 ~-I ~
(d 0 '0 -H 0 rd rtf H
H H (a r-+ ~Q a4 10
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32
Example 3
4 oil mixtures were prepared according to the scheme
as presented in Table 4. Two oil mixtures were subjected
to a clay treatment using Tonsil 411 clay as obtainable
from Sued Chemie, Muenchen (D). The anti-oxidant and
copper passivator additives were added after the clay
treatment. The properties of the oil mixtures were
measured and the oil mixtures were subjected to the IEC
OXIDATION TEST at 500h/120 C.
CA 02611649 2007-12-10
WO 2006/136591 PCT/EP2006/063433
33
co O N O C)
w O O O M Ln ~ ~{ N
~
ri N
m I-fl O N
Go N
O N O 0
N O O H O M N lfl U) l0 Op
I M N ~ O
rl
m O p
I
O
OD
N O Ln O O r- N
O i ~ m
H .
~ C) 0 H V rl ~
00 N 0 0
o co NI,
o rI v M N
M ~ O
O M
~ c~ O H >
Ol O
H 0)
O
~D O O M r~
~ H ~ O O
r-I
O Lf1 r-i
M N N N I I
01 l0 l0 l0 O 0
ri 0 m in m
[~ U1 r I rl H
M M
N H Lf1 lll L(1 O O
0 H H H H w A
H A A A A
m ul EQ
0\0 0\0 0\0 0\0 \ o\0 N r+ c+
11 3 41 41 o\o tl 1.1 U E e ~
i U
0
~-I o
01%
}4 (0.'
~ ~ 0
O ~ -~ ~
a) -.-i 5 [J4
co E5
(d -~ (a r-i z
0 U1 =H U U 0
=ri r, r-i 0 0 U o H
+-) U 0 ?, o E-~
H ?C N O O W aC
M O O L') 04
~1 rI ~I .~ E~ J-1 i d~ H F:4 H
44 ri ~ H ~ i ~ H N ~ w ?+ ~+ >4 a ~n
+ 1 r-i rl m ::5 a) .C r-i 0 E- P H O H
F: -rl ~ ~-I Ul ~ 4J 0 4J E-4 H H H > A
a) 0 U rd =li 41 N N r4 m z p U) m vi
P., rLf rd I rd m U) H z O O O
H N i r-i N N -r-1 Z3 =r-I 0 H U U U fY
lw cn a~ ~~~ ~4 -~ 4-) a 0 U) U) u) 0 H
4) (d .(I fd N 1-) t0 J-) ,k', -I W H H H A U
a) r-A Q ~ ~4 r_: =11 0 0 a) x > > >
.El a) a) >1 A N =r-i 04 U) 04 = ~ a
a P, F-I A (d 0 1 ~D Z Z Z w w
(d (d E-1 (15 =rl -H r-i ~ 41 S I 0 H H H Q$ H
E-~ U) 10 A U -i ,.q a w a x x x a1 A
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WO 2006/136591 PCT/EP2006/063433
34
Ul O
O r-i
04 0 O O'
l0 M
Ul N 0 0
N U1 O O O Ln
(d 1
04 0 0 0
V V
N N
O O
J+ N H H
O O O
~ lfl L(1
O 0 rl
I 0 0
O
0 V O =
v 0
rI
~ =~ k
f~ -k
w v
r-I
~D
W
U U U
M \ \ \
Ln U) Ln Ln
M N N N
H H H
M rl r-i r~
Lfl lO 0 l0
z U U U
H W W W
Q H H H
o\0
rn
U v
o J..1
0 ~ LI-4
N Ul fd
U r-I N G'.
o U 0
O 0 =r-1
N 0 U O 1J
r-1 0 0 01 fd
IIl 0 ~-I
U O ~ H [~+ 0 =~
-O 0 0 ~ 4-I O 04 U ~I
4-) r-I E-i (d 0 -H U) ;:$
~~ ~C H r-I N Q ~n ~~
~ p 0 ~ 4-4 = 41 ~4 -~
0 r, U r~ (d ~4 U t7~ d
~H Cll N rl bl a) O ~ U)
~ 4) x rl JW ~ U) r-I '14
r I Q~ P4' 0 ~ E-~ JJ U] ~
,~ ~ p; U U U1 O -~ -k
~ rd 0 O x ~
E-i C12 ~4 H H J-1 Lf)
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Table 4 shows that the oil formulation based on the
Fischer-Tropsch derived base oil has a low viscosity at
-30 C in combination with excellent oxidative stability
properties. The gassing tendency of the Mixture Z of
5 Table 4 can be improved by adding an aromatic solvent as
illustrated in Table 5.
Table 5
Sample Identification Z Z'
GTL base oil-1 Wto 94,68 94,18
naphthenic base oil-1 Wt%
Mineral Paraffinic base
Wt% 5,00 5,00
oil-1
Dibenzyldisulfid (Antiwear
Wt% 0,02 0,02
additive)
Clay treatment (Tonsil) Wt% 1 1
1-[bis(2-ethylhexyl)amino-
Mg/kg 10 10
methyl]benzotriazole
Shellsol A 150 (aromatic
Wt% none 0,5
hydrocarbon solvent)
Antioxidant BHT Wt s 0,30 0,30
GASSING TENDENCY measured
according to BS 5797 mm3/min > 0 -8,9
Example 4
Three oil formulations A-C were made using the GTL
Base Oils 1, 2 and 3 of Table 1 according to the
10 formulation as listed in Table 6. The oil formulations
A-C were subjected to a clay treatment using Tonsil 411
clay as obtainable from Sued Chemie, Munchen (D).The
anti-oxidant and copper passivator additive were added
after the clay treatment.
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36
The oils were tested with the test methods listed in
Table 6. The results show that excellent oils for use as
electrical oils.
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37
Table 6
Oil properties Oil A Oil B Oil C
Formulation
GTL BO-1 Wt% 94,7
GTL BO-2 Wt% 98,7
GTL BO-3 Wto 98,7
Paraffinic-base oil 1 Wt% 5,0
Paraffinic-base oil 2 wto 1,0 1,0
Dibenzyldisulfide mg/kg 200 200 200
1- [bis (2-ethylhexyl) -
aminomethyl]benzo- mg/kg 10 10 10
triazole
Ionol 861805 % 0,3 0,3 0,3
Test results
TEST DIMENS.METHODE
FLASH POINT C ISO 2592 160 226 263
DIN ISO
POUR POINT C 3016 -51 -30 -18
Not
DIN measure
KIN.VISCOSITY 40 C mm2/s 51562 7,8 17,5 d
DIN
KIN.VISCOSITY 100 C mm2/s 51562 2,4 4,1 7,8
IEC OXIDATION TEST 500h/120 C
IEC 61125/C
- Total acidity mgKOH/g 0,02 0,02 0,04
- Sludge Gew.o < 0,006 <0,008 < 0,007
- Dielectr. Dissip. F.
90 C 0,0035 0,0004 0,0004
