U.S. patent application number 16/303169 was filed with the patent office on 2020-10-15 for lubricating fluid.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Lixin RAN, Peter William Robert SMITH, Xi WANG.
Application Number | 20200325413 16/303169 |
Document ID | / |
Family ID | 1000004930810 |
Filed Date | 2020-10-15 |
United States Patent
Application |
20200325413 |
Kind Code |
A1 |
RAN; Lixin ; et al. |
October 15, 2020 |
LUBRICATING FLUID
Abstract
A lubricating fluid suitable for use as a shock absorber fluid
is disclosed. The lubricating fluid comprises at least 40 wt %,
based upon the weight of the lubricating fluid, of a GTL base oil,
has a viscosity index in the range of from 50 to 1000, and a pour
point of below -30.degree. C.
Inventors: |
RAN; Lixin; (Shanghai,
CN) ; WANG; Xi; (Shanghai, CN) ; SMITH; Peter
William Robert; (Merseyside, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
1000004930810 |
Appl. No.: |
16/303169 |
Filed: |
May 23, 2017 |
PCT Filed: |
May 23, 2017 |
PCT NO: |
PCT/EP2017/062473 |
371 Date: |
November 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2223/047 20130101;
C10M 2203/003 20130101; C10M 2205/173 20130101; C10M 2209/084
20130101; C10M 2203/065 20130101; C10N 2030/02 20130101; C10N
2040/08 20130101; C10M 2215/26 20130101; C10M 111/04 20130101; C10M
169/04 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 105/06 20060101 C10M105/06; C10M 111/02 20060101
C10M111/02; C10M 137/10 20060101 C10M137/10; C10M 133/54 20060101
C10M133/54; C10M 141/10 20060101 C10M141/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2016 |
CN |
201610352708.2 |
Claims
1. A lubricating fluid comprising: (a) at least 40 wt %, based upon
the weight of the lubricating fluid, of a GTL base oil; (b) from 5
to 25 wt %, based upon the weight of the lubricating fluid, of
alkylbenzene or alkylnaphthalene; and (c) from 0.1 to 20 wt %,
based upon the weight of the lubricating fluid, of a viscosity
index improver; wherein the lubricating fluid has a viscosity index
in the range of from 50 to 1000, and a pour point of below
-30.degree. C.
2. The lubricating fluid according to claim 1, comprising in the
range of from 50 to 90 wt % of the GTL base oil.
3. The lubricating fluid according to claim 1, comprising from 5 to
25 wt % of a mixture of alkylbenzenes that are mono- or
di-substituted with linear and/or branched alkyl groups, wherein
the alkyl groups are C.sub.6-C.sub.20 alkyl groups.
4. The lubricating fluid according to claim 1, wherein the
viscosity index improver is chosen from polymers and copolymers of
methacrylate, butadiene, olefins, or alkylated styrenes.
5. The lubricating fluid according to claim 1, comprising a
metal-containing or metal-free alkylthiophosphate, in an amount of
from about 0.4% by weight to about 1.4% by weight of the
lubricating fluid.
6. The lubricating fluid according to claim 1 comprising an acrylic
copolymer or a fatty amine ethoxylate in an amount less than 0.1 wt
%, based up on the weight of the lubricating fluid.
7. (canceled)
8. A method of operating a shock absorber in a vehicle, the method
comprising: providing the shock absorber with a lubricating fluid,
wherein the lubricating fluid comprises: (a) at least 40 wt %,
based upon the weight of the lubricating fluid, of a GTL base oil;
(b) from 5 to 25 wt %, based upon the weight of the lubricating
fluid, of alkylbenzene or alkylnaphthalene; and (c) from 0.1 to 20
wt %, based upon the weight of the lubricating fluid, of a
viscosity index improver; wherein the lubricating fluid has a
viscosity index in the range of from 50 to 1000, and a pour point
of below -30.degree. C.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a lubricating fluid which
is suitably used as shock absorber fluid. The present invention
further relates to the use of the lubricating fluid in a shock
absorber.
BACKGROUND OF THE INVENTION
[0002] A shock absorber (sometimes referred to as a damper) is a
mechanical device designed to smooth out or damp a sudden shock
impulse and dissipate kinetic energy. Shock absorbers are an
important part of automobile, motorbike or bicycle suspensions,
aircraft landing gear, train suspensions, and the supports for many
industrial machines. Large shock absorbers are also used in
architecture and civil engineering to reduce the susceptibility of
structures to earthquake damage and resonance.
[0003] Shock absorbers convert kinetic energy to heat energy, which
can then be dissipated. Hydraulic shock absorbers are composed of a
cylinder with a sliding piston inside. The cylinder is filled with
a shock absorber fluid. This fluid-filled piston/cylinder
combination is also referred to as a dashpot. In a vehicle the
wheel suspension usually contains several shock absorbers, mostly
in combination with pressure resilient means such as coil springs,
leaf springs, or torsion bars. These springs are not shock
absorbers as springs only store and do not dissipate or absorb
energy. If a wheel is put into a horizontal motion, the spring will
absorb the up- and downward force, and convert this into heat. The
shock absorber, along with hysteresis in for instance the tyres of
the wheel, dampens the motion of the unsprung weight up and down,
thereby effectively damping the wheel bounce. This is achieved by
converting the kinetic energy into heat through fluid friction due
to the flow of the shock absorber fluid through a narrow orifice,
such as an internal valve.
[0004] WO201063752 discloses fluids that may be used as shock
absorber fluids that have high biological degradability and high
compatibility with viscosity improvers, particularly at low
temperatures. The fluids comprise a base oil composition and a
viscosity index improver. The base oil composition comprises GTL
base oil and an ester of a polyhydroxy compound.
[0005] The present inventors have sought to provide lubricating
fluids suitable for use as shock absorber fluids having
advantageous properties, e.g. better long term shear stability
and/or better low temperature viscosity properties than
commercially available shock absorber fluids.
SUMMARY OF INVENTION
[0006] The present inventors have found that lubricating fluids
suitable for use as shock absorber fluids can be prepared from an
advantageous combination of a GTL base oil, an alkylbenzene or
alkylnaphthalene, and a viscosity modifier. Such a combination
exhibits good shear stability and good low temperature
viscosity.
[0007] Accordingly the present invention provides a lubricating
fluid comprising: [0008] (a) at least 40 wt %, based upon the
weight of the lubricating fluid, of a GTL base oil; [0009] (b) from
5 to 25 wt %, based upon the weight of the lubricating fluid, of
alkylbenzene or alkylnaphthalene; and [0010] (c) from 0.1 to 20 wt
%, based upon the weight of the lubricating fluid, of a viscosity
index improver; wherein the lubricating fluid has a viscosity index
in the range of from 50 to 1000, and a pour point of below
-30.degree. C.
[0011] The lubricating fluid is suitable for use as a shock
absorber fluid but may also find use as a fork oil or as an
industrial lubricant such as a hydraulic fluid or a bearing and
circulating oil.
[0012] The present invention further provides the use of a
lubricating fluid according to the invention in a shock
absorber.
[0013] The present invention yet further provides a vehicle
comprising a lubricating fluid according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The lubricating fluid comprises at least 40 wt %, based upon
the weight of the lubricating fluid, of a GTL base oil. The
lubricating fluid preferably comprises in the range of from 50 to
90 wt % of GTL base oil, based upon the weight of the lubricating
fluid, more preferably of from 60 to 85 wt %.
[0015] The term "GTL base oil" is used to describe base oils that
are synthesised by the Fischer-Tropsch method of converting natural
gas to liquid fuel. They have a very low sulphur content and
aromatic content compared with mineral oil base oils refined from
crude oil and have a very high paraffin constituent ratio. The GTL
base oil may be a mixture of several different GTL base oils,
having different viscosities. Preferably the kinematic viscosity of
the GTL base oil at 100.degree. C. is in the range of from 2 to 10
mm.sup.2/s, more preferably in the range of from 2.5 to 7
mm.sup.2/s. The kinematic viscosity is suitably determined by ASTM
D445. Suitable base oils, known at "GTL 4" and "GTL 3", are
available from Shell.
[0016] The lubricating fluid comprises from 5 to 25 wt %, based
upon the weight of the lubricating fluid, of alkylbenzene or
alkylnaphthalene. Suitably the alkylbenzene or alkylnaphthalene is
a mixture of different alkylbenzene molecules and/or
alkylnaphthalene molecules. The alkylbenzenes and/or
alkylnaphthalenes may be mono- or poly-substituted but are
preferably mono- or di-substituted. In a preferred embodiment, the
lubricating fluid comprises from 5 to 25 wt % of a mixture of
alkylbenzenes that are mono- or di-substituted with linear and/or
branched alkyl groups, wherein the alkyl groups are
C.sub.6-C.sub.20 alkyl groups, preferably C.sub.9-C.sub.15 alkyl
groups. The kinematic viscosity at 40.degree. C. of the
alkylbenzene or alkylnaphthalene (suitably determined by ASTM D445)
is suitably between 3 and 400=.sup.2/s, preferably between 3 and 50
mm.sup.2/s and more preferably between 3 and 10 mm.sup.2/s. The
average relative molecular weight is suitably from 180 to 300,
preferably from 200 to 280, and more preferably from 230 to
260.
[0017] The lubricating fluid comprises from 0.1 to 20 wt %, based
upon the weight of the lubricating fluid, of a viscosity index
improver. The lubricating fluid preferably comprises from 1 to 18
wt % of a viscosity index improver, more preferably from 3 to 10 wt
%.
[0018] Viscosity index improvers (also known as VI improvers,
viscosity modifiers, or viscosity improvers) provide lubricants
with high- and low-temperature operability. These additives impart
shear stability and acceptable viscosity at elevated temperatures
and at low temperatures. Suitable viscosity index improvers include
both low molecular weight and high molecular weight hydrocarbons,
polyesters and viscosity index improver dispersants that can
function as both a viscosity index improver and a dispersant.
Typical molecular weights of these polymers are between about
10,000 to 1,000,000, more typically about 20,000 to 500,000 and
even more typically between about 50,000 and 200,000. Examples of
suitable viscosity index improvers are polymers and copolymers of
methacrylate, butadiene, olefins, or alkylated styrenes.
[0019] Preferably, the viscosity index improver is poly methyl
methacrylate (further referred to as PMMA), i.e. a copolymer of
various chain length methyl and alkyl methacrylates. Particularly
preferred PMMA viscosity index improvers are the commercially
available Viscoplex viscosity improvers (Viscoplex is a tradename
of the Rohm GmbH & CO. KG, Darmstadt, Germany).
[0020] The lubricating fluid suitably further comprises one or more
additives that are typically used in shock absorber fluids. These
additives can be added in the form of an additive package. A
typical additive package includes oxidation inhibitors and
anti-wear agents, but may also include dispersants, detergents,
corrosion and rust inhibitors, metal deactivators, extreme pressure
additives, anti-seizure agents, pour point depressants, wax
modifiers, seal compatibility agents, friction modifiers, lubricity
agents, anti-staining agents, chromophoric agents, anti-foaming
agents and demulsifiers.
[0021] The lubricating fluid preferably comprises an antiwear
additive. Suitable antiwear additives include metal-containing and
metal-free alkylthiophosphates, such as zinc
dialkyldithiophosphates, typically used in amounts of from about
0.4% by weight to about 1.4% by weight of the lubricating
fluid.
[0022] The lubricating fluid preferably comprises an anti-foaming
agent. Silicones and organic polymers are typical anti-foam agents.
Preferably the anti-foaming agent is a low-silicon or no-silicon
anti-foam, such as an acrylic copolymer or a fatty amine
ethoxylate. The amount of anti-foaming agent is suitably less than
1 wt %, based up on the weight of the lubricating fluid, preferably
less than 0.1 wt % and more preferably less than 0.05 wt %.
[0023] The lubricating fluid has a viscosity index in the range of
from 50 to 1000, preferably in the range of from 100 to 600.
Suitably the viscosity index is determined according to ASTM D2272.
If the viscosity index is too low, the lubricating fluid is likely
to be too viscous at low temperatures and too thin at higher
temperatures, and then the lubricating fluid will not function
effectively in a shock absorber.
[0024] The lubricating fluid has a pour point of below -30.degree.
C., preferably below -45.degree. C. Suitably the pour point is
determined according to ASTM D97. If the lubricating fluid has a
higher pour point then the fluid would not flow in cold ambient
conditions and a shock absorber containing the fluid would not
function.
[0025] The lubricating fluid suitably has a kinematic viscosity at
40.degree. C. of at least 7 mm.sup.2/s, preferably at least 10
mm.sup.2/s and more preferably at least 12 mm.sup.2/s. Suitably the
kinematic viscosity at 40.degree. C. is determined according to
ASTM D445. Having such a viscosity is important if the lubricating
fluid is to function effectively in a shock absorber.
[0026] The lubricating fluid suitably has a Brookfield viscosity at
-40.degree. C. of less than 2000 cP, more preferably less than 1500
cP and most preferably less than 1250 cP. Suitably the Brookfield
viscosity at -40.degree. C. is determined by ASTM D2983. Having
such a viscosity is important if the lubricating fluid is to
function effectively in a shock absorber.
[0027] The lubricating fluid suitably has a shear stability at
40.degree. C., measured according to CEC L-45-99, of less than 10%,
more preferably less than 5%, most preferably less than 3%. It is
important that the lubricating fluid has the highest possible shear
stability (and the lowest possible loss of shear stability under
the test conditions) so that, when employed in a shock absorber,
the lubricating fluid has the correct viscosity range for efficient
operation for the longest possible period. If the lubricating
composition has poor shear stability, it will shear down over time
and the viscosity will soon be outside the required range.
[0028] The present invention is described below with reference to
the following Example, which is not intended to limit the scope of
the present invention in any way.
Example
[0029] A shock absorber fluid (Example 1) was prepared having the
formulation shown in table 1:
TABLE-US-00001 TABLE 1 Component Amount (wt %) GTL 4 base oil 10.00
GTL 3 base oil 68.18 Alkylbenzene 15.00 VI improver 6.00 Additive
package for shock 0.75 absorber fluid (contains dispersants,
detergents, anti- wear additives, anti-oxidants) Ashless antiwear
additive 0.05 Low-silicon Antifoam 0.02
Both GTL base oils are available from Shell. The GTL 4 base oil had
a viscosity at 100.degree. C. (measured by ASTM D445) of between
3.80 and 4.20 cSt. The GTL 3 base oil had a viscosity at
100.degree. C. (measured by ASTM D445) of 2.8 cSt. The alkylbenzene
was a mixture of mono-substituted alkylbenzenes having a kinematic
viscosity at 40.degree. C. of between 3 and 5 mm.sup.2/s. The fluid
was prepared by mixing and heating of all the components until a
homogeneous mixture resulted.
Testing
[0030] The shock absorber fluid of Example 1 and two commercial
shock absorber fluids (Comparative Example 1 and Comparative
Example 2) were tested. Table 2 shows the properties that were
tested, the test methods used and the results for Example 1,
Comparative Example 1 and Comparative Example 2.
TABLE-US-00002 TABLE 2 Comparative Comparative Property Test Method
Example 1 Example 1 Example 2 Density at 15.degree. C. (g/cm.sup.3)
ASTM D4052 0.8247 0.8611 0.836 Viscosity at 40.degree. C. (cSt)
ASTM D445 13.086 14.18 14.5018 Viscosity at 100.degree. C. (cSt)
ASTM D445 3.8561 4.0547 4.0913 Viscosity Index ASTM D2272 210.7
206.4 202.3 Brookfield Viscosity at -40.degree. C. (cP) ASTM D2983
1020 2369 1800 Pour point (.degree. C.) ASTM D97 -60 <-45
<-45 Shear stability at 40.degree. C. (% viscosity loss) CEC
L-45-99 2.70 13.50 6.02
[0031] The results show that all three shock absorber fluids had
similar density, viscosities at 40.degree. C. and 100.degree. C.
and viscosity index. The shock absorber fluid of the invention
(example 1) had an improved Brookfield viscosity compared to the
commercial shock absorber fluids (comparative example 1 and
comparative example 2), and also had a better shear stability.
* * * * *