[0001] The present invention relates to environmentally friendly lubricating oil compositions
for automotive engines. Lubricating oil compositions for use in automotive engines
are well known. These compositions usually contain a base fluid which may comprise
mineral oils, hydrocarbon oils and/or synthetic fluids and conventional additives
such as viscosity index (hereafter "VI") improvers, anti-oxidants, corrosion inhibitors,
dispersants, anti-wear additives and sludge control agents. In recent years, automotive
engine oil development has seen a steady trend towards lower viscosity multigrades,
principally to improve fuel efficiency. The predominant viscosity grade has moved
from a typically 20W/50 oil to a 10W/40 or a 5W/40 oil. The manufacturers of automotive
engine equipment have also tightened the specifications for such oils in terms of
oil consumption, bearing protection and shear stability. This has meant that the engine
lubricant has had to become lower in volatility and more shear stable so that these
thinner oils stay in the specified grade band longer. As a result, lubricating oils
compositions based solely on conventional solvent refined mineral oils are no longer
adequate to meet these stringent performance requirements. To meet these performance
requirements, a growing demand has arisen for "special" base oils possessing superior
qualities of volatility, VI and pour point. These special base oils have a VI above
120 and the requirement is primarily met by the use of paraffinic base oils which
include inter alia oils based on hydrocracked wax distillates. It has also been suggested
to use blends of such hydrocracked wax distillates with aliphatic esters in order
to improve the performance of such base oils. These prior art compositions usually
contain 80% w/w or more of a hydrocarbon or mineral oil and upto 20% w/w of an aliphatic
carboxylic acid ester in the base fluid. Such compositions, whilst being very efficient
and being to some extent biodegradable, still leave room for improvement.
[0002] It has now been found that base oil blends can be formulated which not only improve
the biodegradability thereof but achieve the same without loss of performance at the
same time exhibiting relatively lower emissions, lower fuel consumption and lower
oil consumption.
[0003] Accordingly, the present invention is a lubricating oil composition which has a major
proportion of a base fluid which fluid comprises a blend of:
a) at least one ester derivable from isotridecyl alcohol and at least one aliphatic
mono-, di- or polycarboxylic acid, and
b) at least one hydrocarbon oil comprising upto 99.5% w/w of aliphatic hydrocarbons
and no more than 10% w/w aromatic hydrocarbons such that the total of aliphatics and
aromatics is 100% wherein the amount of component (a) in the blend is in the range
from 25-55% w/w.
[0004] As described above, the base fluid comprises a blend of an ester and a hydrocarbon
oil. The ester component (a) is derivable by the reaction of an aliphatic mono-, di-
and/or poly-carboxylic acid with, isotridecyl alcohol under esterification conditions.
[0005] Specific examples of such esters include the isotridecyl esters of octane-1,8-dioic
acid, 2-ethylhexane-1,6-dioic acid, nonane-1,9-dioic acid, decane-1,10-dioic acid
and dodecane-1,12-dioic acid.
[0006] Similarly, the hydrocarbon oil component (b) in the blend suitably is a hydrocracked
wax distillate. More specifically, such hydrocarbon oils can contain upto 99.5% w/w,
preferably upto 97% w/w, of aliphatic hydrocarbons and no more than 10% w/w of aromatic
hydrocarbons. The expression "aliphatic hydrocarbons" as used herein and throughout
the specification is meant to include open chain aliphatic hydrocarbons as well as
cycloaliphatic hydrocarbons such as e.g. naphthenic hydrocarbons. The total polycyclic
aromatic hydrocarbons in the hydrocarbon oil is suitably less than 10 ppm, preferably
less than 5 ppm and more preferably less than 1 ppm. Typically such hydrocarbon oil
contains from 92-97% w/w of aliphatics and 3-8% w/w of aromatics.
[0007] The hydrocarbon oil component (b) in the blend is suitably prepared by feeding a
waxy distillate through a hydrocracker at 70-95% conversion under elevated temperature
and hydrogen pressure. In the first stage of this hydrocracker, sulphur and nitrogen
compounds are removed and in the second stage the aromatics are hydrogenated to naphthenes;
the hydrogenated products including the naphthenes are cleaved and rearranged to produce
a controlled range of paraffins and isoparaffins. Fuels and lubricant products are
separated by atmospheric distillation from the resultant hydrocracked products and
the 5-35% heavy component is the hydrocarbon fraction used as the hydrocarbon oil
component (b) in the blend. A product produced by this method is substantially free
of any unsaturates. This feedstock can be further refined, if necessary, by conventional
techniques such as additional fractionation, extraction or dewaxing to obtain the
finished product. The resultant hydrocarbon oil has the following physical characteristics:
Colour (ASTM D 1500) |
1.5 Max |
Density (ASTM 1298) |
0.83 |
KV(40°)/cSt (ASTM D 445) |
17.28 |
KV(100°C)/cSt (ASTM D 445) |
3.99 - 4.22 |
VI (ASTM D 2270) |
123 - 128 |
Pour point/°C (ASTM D 97) |
-24 - -27 |
% S (XRF NFM 07053) |
0.08 - 0.15 |
Total N/ppm |
ca 12 |
Aromatics by HPLC/% |
ca 7.7 |
Aliphatics By HPLC/% |
ca 92.3 |
Polycyclic aromatics/ppm - |
0.1 |
[0008] Of the aliphatic hydrocarbons in this hydrocarbon oil component (b), about 20% w/w
comprises isoparaffins having an average carbon number of about 27.
[0009] The relative amounts of the ester component (a) and the hydrocarbon oil component
(b) in the base fluid within the specified ranges above will depend upon the nature
of the two components and their relative viscosities. For instance, if the hydrocarbon
component (b) is within the physical characteristic specification defined above, and
the ester component (a) is isotridecyldodecanedioate, the amount of ester (a) in the
blend may suitably vary from 30-50% w/w, preferably from 40-50% w/w.
[0010] In addition to the above blended base fluid, the lubricating composition of the present
invention comprises minor proportions of conventional additives which include inter
alia the following: one or more sludge dispersants, one or more VI improvers, one
or more anti-wear additives, and one or more anti-oxidants. Typically, the additive
package used is known to comprise components which meet the stringent requirements
of an API Performance Classification "SG". These requirements include successful testing
in the following categories: rust test, dispersancy test, piston varnish test, low
temperature sludge test and wear test. Such additives are commercially available as
an additives package sold e.g. as an "SG Additive Package" under the names GBX 2900
and GBX 2905 (both ex Adibis Ltd, UK). Such an additive package suitably forms from
10-20% w/w, preferably from 11-16% w/w of the formulated lubricating composition.
Examples of compounds that may be present in such a package include anti-rust agents
such as the overbased calcium or magnesium sulphonates or phenates; anti-wear agents
such as the zinc dithiophosphates, preferably the zinc dialkyl dithiophosphates containing
5-15% w/w phosphorus (normally prepared using a mixture of secondary alcohols and
representing 0.05% -0.5% w/w of phosphorus, typically 0.1-0.14% phosphorus in the
finished oil); ashless dispersancy agents such as derivatives of long chain hydrocarbon
substituted succinimides, especially the polyisobutenyl succinimides; and sludge dispersants
which are oil soluble salts such as amides, imides, oxazolines and esters of mono-
or di-carboxylic acids or anhydrides.
[0011] The anti-oxidants typically contain phenolic compounds and a typical antioxidant
is commercially available as ADX 545A (ex Adibis Ltd). The anti-oxidants are suitably
present in an amount from 0.01-5% w/w, preferably from 0.1-2.0% w/w of the formulated
lubricating composition.
[0012] The lubricating compositions also contain one or more VI improvers. Examples of such
VI improvers include polymethacrylate type dispersants commercially sold as Plexol
1420 VX (Regd Trade Mark, ex Rohm GmbH) and hydrotreated polyisoprenes commercially
sold as Shellvis 200 (Regd Trade Mark, ex Shell UK Ltd). In the case of the latter,
it may used as a solution in the hydrocarbon oil component (b) above. The VI improvers
are suitably present in an amount from 2 to 5% w/w of the formulated lubricating composition.
Thus a typical formulated lubricating composition (A) can be represented by the following
components in w/w %:
SG Additives Package (GBX 2905, ex Adibis Ltd) |
15.4 |
ADX 545A (anti-oxidant, ex Adibis Ltd) |
1.0 |
Plexol* 1420 (VI improver, ex Rohm GmbH) |
3.1 |
Shellvis* 200 (VI improver, 10% soln, ex Shell UK Ltd) |
6.0 |
Isotridecyldodecanedioate |
22.59 and |
Hydrocarbon oil** |
52.71 |
* Registered Trade Mark |
** The hydrocarbon oil is a hydrotreated wax distillate containing 92.3% w/w aliphatics
and 7.7% w/w aromatics which is substantially free of any unsaturates and had a polycyclic
aromatic content of about 0.1 ppm. An oil of this type is described above. |
[0013] Variations of the formulated lubricating composition (A) shown above can also be
formulated in which the relative amounts of ester and hydrocarbon oil are (B) 32.28%
and 49.32% respectively or (C) 39.5% each.
[0014] It was found that the performance of the lubricating compositions formulated in this
manner upon engine testing showed relatively lower emissions, lower fuel consumption,
lower oil consumption and low nitrogen oxides emission. In addition, the formulated
lubricating compositions according to the present invention were at least 80% biodegradable
as measured by the CEC standard test procedure. The present invention is further illustrated
with reference to the following Examples:
Examples - General
[0015] A base fluid was prepared using isotridecyldodecanedioate, and a hydrocracked wax
distillate having the following physical characteristics:
Property |
Typical Specification |
Test Method |
Colour |
1.5 max |
ASTM D 1500 |
Density |
0.83 |
ASTM D 1298 |
KV 40/cSt |
17.28 |
ASTM d 445 |
KV 100/cSt |
3.99 |
ASTM d 445 |
VI |
128 |
ASTM D 2270 |
PMC/°C |
220 |
ASTM D 93 |
Pour Point |
-27 |
ASTM D 97 |
Demulse/mins |
<5 |
NFT* 60-125 |
Noack volatility/% |
15.8 |
DIN 51581 |
Sulphur/% |
0.08 |
XRF NFM 07053 |
CA/% |
2 |
Brandes Method |
*Correlates with ASTM D 1401 |
[0016] This hydrocarbon oil was used to prepare formulated lubricating oil compositions
according to the formulation in (A) in the following Examples 1-3.
Example 1
[0017]
SG Additive Package (GBX 2905, ex Adibis Ltd) |
15.4% w/w |
ADX 545A (Anti-oxidant, ex Adibis Ltd) |
1.0% w/w |
Plexol* 1420 (VI improver, ex Rohm GmbH) |
3.1% w/w |
Shellvis* 200 (VI improver, 10% solution, ex Shell UK Ltd) |
6.0% w/w |
Isotridecyl dodecanedioate |
22.59% w/w |
Hydrocarbon oil (as above) |
52.71% w/w |
[0018] The formulation was prepared using standard lubricant blending techniques described
e.g. in "Lubricants and Related Products" by D Klamann, published by Verlag Chemie,
1984.
[0019] The formulated composition had the following characteristics:
Property |
Limits |
Methods |
Viscosity @ 100°C |
13.6-14.5 cSt |
ASTM D 445 |
Viscosity @ 40°C |
75.0-83.0 cSt |
ASTM D 445 |
Viscosity @ -25°C |
<3500 cP |
ASTM D 2602 |
Noack volatility |
8.5-11.0% |
DIN 51581 |
Biodegradability |
>80% |
CEC-L-33-T-82 |
Calcium |
0.300-0.332 |
ICP |
Phosphorus |
0.102-0.114 |
ICP |
Zinc |
0.105-0.135 |
ICP |
Example 2
[0020]
SH Additive Package (eg OS 99099, ex Lubrizol Ltd) |
15% w/w |
Viscoplex* 2540 (VI Improver, ex Rohm GmbH) |
3.0% w/w |
Shellvis* 201 (VI Improver, ex Shell UK Ltd) |
3.8% w/w |
Isotridecyl dodecanedioate |
38.1% w/w |
Hydrocarbon oil (as above) |
40.1% w/w |
[0021] The formulated composition had the following characteristics:
Property |
Limits |
Method |
Viscosity @ 100°C |
14.0 cSt |
ASTM D445 |
Viscosity @ -25°C |
3200 cP |
ASTM D2602 |
Noack volatility |
10.7% |
DIN 51581 |
Biodegradability |
87% |
CEL-L-33-T-82 |
Calcium content |
0.283 |
ICP |
Phosphorus content |
0.119 |
ICP |
Zinc content |
0.128 |
ICP |
Example 3
[0022]
SG Additive Package (eg GBX2905, ex Adibis Ltd) |
16.4% w/w |
Plexol* 1420 (VI Improver, ex Rohm GmbH) |
3.1% w/w |
GBX 2715 (VI Improver, ex Adibis Ltd) |
5.0% w/w |
Isotridecyl dodecanedioate |
40.0% w/w |
Hydrocarbon oil (as above) |
35.5% w/w |
[0023] The formulated composition had the following properties:
Property |
Limits |
Method |
Viscosity @ 100°C |
14.5 cSt |
ASTM D445 |
Viscosity @ -25°C |
3300 cP |
ASTM D2602 |
Noack volatility |
10.4% |
DIM 51581 |
Biodegradability |
86% |
CEC-L-33-T-82 |
Calcium content |
0.310% |
ICP |
Phosphorus content |
0.108% |
ICP |
Zinc content |
0.125% |
ICP |
[0024] Upon standard engine testing each of the formulations described in Examples 1-3 above
using the API-GS method, the following properties were observed:
![](https://data.epo.org/publication-server/image?imagePath=1993/30/DOC/EPNWA1/EP92311497NWA1/imgb0001)
[0025] The biodegradability of the formulated lubricating composition according to the present
invention was tested and compared with commercially available products using the test
method shown in the table above. The results are tabulated below:
Present Invention |
91% |
Mobil 1 |
45% |
Castrol GTX |
63% |
Shell Gemini |
66% |
Castrol Syntron |
41% |
[0026] From the above it is clear that the formulated compositions according to the present
invention containing the blended base fluid according to the present invention show
superior properties to those of prior art, especially in respect of their biodegradability.
1. A lubricating oil composition which has a major proportion of a base fluid which fluid
comprises a blend of:
a) at least one ester derivable from isotridecyl alcohol and at least one aliphatic
mono-, di- or poly-carboxylic acid, and
b) at least one hydrocarbon oil comprising up to 99.5% w/w of aliphatic hydrocarbons
and no more than 10% w/w of aromatic hydrocarbons such that the total of aliphatics
and aromatics is 100%, wherein the amount of component (a) in the blend is in the
range from 25-55% w/w.
2. A lubricating oil composition according to claim 1 wherein the ester component (a)
is selected from isotridecyl esters of
i) octane-1,8-dioic acid,
ii) 2-ethylhexane-1,6-dioic acid,
iii) nonane-1,9-dioic acid,
iv) decane-1,10-dioic acid, and
v) dodecane-1,12-dioic acid.
3. A lubricating oil composition according to claim 1 or 2 wherein the hydrocarbon oil
component (b) is a hydrocracked wax distillate.
4. A lubricating oil composition according to any one of the preceding claims wherein
the hydrocarbon oil component (b) contains less than 10 ppm of polycyclic aromatic
hydrocarbons, from 92-97% w/w of aliphatic hydrocarbons and 3-8% w/w of aromatic hydrocarbons.
5. A lubricating oil composition according to any one of the preceding claims wherein
the aliphatic hydrocarbons in the hydrocarbon oil component (b) comprise about 20%
w/w of isoparaffins having an average carbon number of about 27.
6. A lubricating oil composition according to any one of the preceding claims wherein
the ester component (a) is isotridecyl dodecanedioate and the amount of ester in the
blend is in the range from 30-50% w/w.
7. A lubricating oil composition according to any one of the preceding claims wherein
said composition comprises, in addition, minor proportions of one or more additives
selected from: sludge dispersants, ashless dispersancy agents, VI improvers, anti-wear
additives, anti-rust agents and anti-oxidants.
8. A lubricating oil composition according to claim 7 wherein the anti-rust agent is
an overbased calcium or magnesium sulphonate or phenate; the anti-wear agent is a
zinc dithiophosphate; the ashless dispersancy agent is a long chain hydrocarbon substituted
succinimide; the sludge dispersant is an oil soluble salt such as amides, imides,
oxazolines and esters of mono- or di-carboxylic acids or anhydrides; the anti-oxidant
is a phenolic compound; and the VI improver comprises a polymethacrylate dispersant
or a hydrotreated polyisoprene.
9. A lubricating oil composition according to any one of the preceding claims wherein
said composition is at least 80% biodegradable as measured by the CEC standard test
procedure.