U.S. patent application number 10/678468 was filed with the patent office on 2004-08-12 for high viscosity index wide-temperature functional fluid compositions and methods for their making and use.
Invention is credited to Galiano-Roth, Angela Stefana, Keeney, Angela J., Sanchez, Eugenio.
Application Number | 20040154957 10/678468 |
Document ID | / |
Family ID | 32829664 |
Filed Date | 2004-08-12 |
United States Patent
Application |
20040154957 |
Kind Code |
A1 |
Keeney, Angela J. ; et
al. |
August 12, 2004 |
High viscosity index wide-temperature functional fluid compositions
and methods for their making and use
Abstract
This invention relates to lubricants comprising base stocks and
base oils that exhibit an unexpected combination of high viscosity
index (130 or greater) and a ratio of measured-to-theoretical
high-shear/low-temperatur- e viscosity at -30 C or lower and the
methods of making them. Specifically, the present invention relates
to novel high viscosity index, low-viscosity lubricants usable as
wide-temperature lubricants, for example hyrdraulic oils,
comprising novel low-viscosity base stocks, with improved
performance in low-temperature viscosity, and methods to produce
them.
Inventors: |
Keeney, Angela J.; (Oxford,
GB) ; Sanchez, Eugenio; (Turnersville, NJ) ;
Galiano-Roth, Angela Stefana; (Mullica Hill, NJ) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P. O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
32829664 |
Appl. No.: |
10/678468 |
Filed: |
October 3, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60432591 |
Dec 11, 2002 |
|
|
|
Current U.S.
Class: |
208/18 ;
208/19 |
Current CPC
Class: |
C10M 2203/1025 20130101;
C10M 2203/1006 20130101; C10M 2205/173 20130101; C10M 2203/1065
20130101; C10M 2209/084 20130101; C10N 2030/02 20130101; C10N
2030/06 20130101; C10N 2020/02 20130101; C10M 171/02 20130101; C10N
2040/08 20130101 |
Class at
Publication: |
208/018 ;
208/019 |
International
Class: |
C10M 159/00 |
Claims
What is claimed is:
1. A functional fluid comprising: a) a base stock or base oil, said
base stock or base oil having the properties of: (i) a viscosity
index (VI) of about 130 or greater; (ii) a pour point of about -10
C or lower; (iii) a ratio of measured-to-theoretical
low-temperature viscosity equal to about 1.2 or less, at a
temperature of about -30 C or lower, where the measured viscosity
is cold-crank simulator viscosity and where theoretical viscosity
is calculated at the same temperature using the Walther-MacCoull
equation wherein said base stock or base oil is not a Group IV base
stock or base oil; and b) at least one additive.
2. A functional fluid comprising: a) at least one base stock or
base oil wherein said base stock or base oil has a VI of at least
130 produced by a process which comprises: (i) hydrotreating a
feedstock having a wax content of at least about 60 wt. %, based on
feedstock, with a hydrotreating catalyst under effective
hydrotreating conditions such that less than 5 wt. % of the
feedstock is converted to 650 F (343 C) minus products to produce a
hydrotreated feedstock whose VI increase is less than 4 greater
than the VI of the feedstock; (ii) stripping the hydrotreated
feedstock to separate gaseous from liquid product; (iii)
hydrodewaxing the liquid product with a dewaxing catalyst which is
at least one of ZSM-48, ZSM-57, ZSM-23, ZSM-22, ZSM-35, ferrierite,
ECR-42, ITQ-13, MCM-71, MCM-68, beta, fluorided alumina,
silica-alumina or fluorided silica alumina under catalytically
effective hydrodewaxing conditions wherein the dewaxing catalyst
contains at least one Group 9 or Group 10 noble metal; and b) at
least one additive.
3. A functional fluid comprising: a) at least one base stock or
base oil wherein said base stock has a VI of at least 130 produced
by a process which comprises: (i) hydrotreating a lubricating oil
feedstock having a wax content of at least about 50 wt. %, based on
feedstock, with a hydrotreating catalyst under effective
hydrotreating conditions such that less than 5 wt. % of the
feedstock is converted to 650 F (343 C) minus products to produce a
hydrotreated feedstock to produce a hydrotreated feedstock whose VI
increase is less than 4 greater than the VI of the feedstock; (ii)
stripping the hydrotreated feedstock to separate gaseous from
liquid product; (iii) hydrodewaxing the liquid product with a
dewaxing catalyst which is at least one of ZSM-22, ZSM-23, ZSM-35,
ferrierite, ZSM-48, ZSM-57, ECR-42, ITQ-13, MCM-68, MCM-71, beta,
fluorided alumina, silica-alumina or fluorided silica-alumina under
catalytically effective hydrodewaxing conditions wherein the
dewaxing catalyst contains at least one Group 9 or 10 noble metal;
(iv) hydrofinishing the product from step (3) with a mesoporous
hydrofinishing catalyst from the M41S family under hydrofinishing
conditions; and b) at least one additive.
4. A functional fluid comprising: a) at least one base stock
wherein said base stock has a VI of at least 130 produced by a
process which comprises: (i) hydrotreating a lubricating oil
feedstock having a wax content of at least about 60 wt. %, based on
feedstock, with a hydrotreating catalyst under effective
hydrotreating conditions such that less than 5 wt. % of the
feedstock is converted to 650 F (343 C) minus products to produce a
hydrotreated feedstock to produce a hydrotreated feedstock whose VI
increase is less than 4 greater than the VI of the feedstock; (ii)
stripping the hydrotreated feedstock to separate gaseous from
liquid product; (iii) hydrodewaxing the liquid product with a
dewaxing catalyst which is ZSM-48 under catalytically effective
hydrodewaxing conditions wherein the dewaxing catalyst contains at
least one Group 9 or 10 noble metal; (iv) Optionally,
hydrofinishing the product from step (3) with MCM-41 under
hydrofinishing conditions; and b) at least one additive.
5. The functional fluid as in claim 2, 3 or 4 wherein said
feedstock is a synthetic gas to liquid feedstock.
6. The functional fluid as in claims 2, 3 or 4 wherein said
feedstock is made by a Fischer-Tropsch process.
7. The functional fluid having improved Brookfield viscosity at -20
F or lower comprising the base stock or base oil of claims 1, 2, 3
or 4 and at least one performance enhancing additive.
8. The functional fluid having improved Brookfield viscosity at -20
F or lower comprising the base stock or base oil of claims 1, 2, 3
or 4 and at least one performance enhancing additive, where said
performance enhancing additive is not a viscosity index
improver.
9. A functional fluid composition comprising the base oil or base
stock of any one of the claims 1, 2, 3 or 4, wherein the Brookfield
viscosity is less than or equal to about 40000 cP at -20 F.
10. A functional fluid composition comprising the base oil or base
stock of any one of the claims 1, 2, 3 or 4, wherein the Brookfield
viscosity is less than or equal to about 28000 cP at -20 F.
11. A functional fluid composition comprising the base oil or base
stock of any one of the claims 1, 2, 3 or 4, wherein the Brookfield
viscosity is less than or equal to about 6500 cP at -20 F.
12. A functional fluid composition comprising the base oil or base
stock of any one of the claims 1, 2, 3 or 4, wherein the Brookfield
viscosity is less than or equal to about 6200 cP at -20 F
13. The method of making a functional fluid having improved
Brookfield viscosity at -20 F or lower comprising incorporating a
base stock or base oil having the properties of (a) a viscosity
index (VI) of 130 or greater, (b) a pour point of -10 C or lower,
(c) a ratio of measured-to-theoretical low-temperature viscosity
equal to 1.2 or less, at a temperature of -30 C or lower, where the
measured viscosity is cold-crank simulator viscosity and where
theoretical viscosity is calculated at the same temperature using
the Walther-MacCoull equation. wherein said base stock or base oil
is not a Group IV base stock or base oil.
14. A method of improving the Brookfield viscosity of a base stock
comprising incorporating said base stock or base oil of any one of
the claims 1, 2, 3 or 4.
15. A method of improving the Brookfield viscosity of a functional
fluid comprising incorporating a base stock or base oil of any one
of the claims 1, 2, 3 or 4.
16. A method of improving the Brookfield viscosity of a hydraulic
oil comprising incorporating a base stock or base oil of any one of
the claims 1, 2, 3 or 4.
17. A method of improving a functional fluid by admixing the base
oil or base stock of any one of the claims 1, 2, 3 or 4, wherein
the Brookfield viscosity of the final mixture is less than or equal
to about 40000 cP at -20 F.
18. A method of improving a functional fluid by admixing the base
oil or base stock of any one of the claims 1, 2, 3 or 4, wherein
the Brookfield viscosity of the final mixture is less than or equal
to about 28000 cP at -20 F.
19. A method of improving a functional fluid by admixing the base
oil or base stock of any one of the claims 1, 2, 3 or 4, wherein
the Brookfield viscosity of the final mixture is less than or equal
to about 6500 cP at -20 F.
20. A method of improving a functional fluid by admixing the base
oil or base stock of any one of the claims 1, 2, 3 or 4, wherein
the Brookfield viscosity of the final mixture is less than or equal
to about 6200 cP at -20 F
21. Any one of the proceeding claims wherein the functional fluid
is a hydraulic oil.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/432,591 filed Dec. 11, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to novel high viscosity index,
low-viscosity lubricants usable as wide-temperature hydraulic oils
comprising novel low-viscosity base stocks, with improved
performance in low-temperature viscosity, and the methods to
produce them. The novel base stocks and base oils incorporated into
this invention exhibit an unexpected combination of high viscosity
index (130 or greater) and a ratio of measured-to-theoretical
high-shear/low-temperature viscosity at -30 C or lower and the
methods of making them.
BACKGROUND OF THE INVENTION
[0003] Hydraulic equipment owners require their equipment to
operate effectively over a wide temperature range. For example,
cargo handling hydraulic systems aboard cargo ships must be able to
operate regardless of the prevailing climate, which can range from
tropical to arctic conditions.
[0004] Consequently, hydraulic oils have been developed which have
good low-temperature flow properties for service under severe cold
climatic conditions, and which provide good high-temperature
performance for hot climatic conditions. In order to achieve the
desired wide temperature working range, hydraulic oils are commonly
formulated in two ways. The first standard formulation technique
involves using mixtures of solvent-refined paraffinic base oil(s)
and solvent-refined naphthenic base oil(s), with added shear stable
viscosity modifier and pour point depressant. The second standard
formulation technique involves using polyalpha olefin base oil
(PAO, Group IV base stock).
[0005] The first technique requires a more complex formulation
approach but is generally preferred because it is more
cost-effective than the second technique which requires an
expensive, special base stock such as PAO. Also, the use of
solvent-refined naphthenic base oil is often required to improve
the low-temperature viscosity of the solvent-refined paraffinic
base oils used in the mineral oil mixture recited in Option
(1).
[0006] A usable wide-temperature hydraulic oil generally meets the
following laboratory bench test performance levels in order to meet
the service expectations of hydraulic equipment users:
[0007] (a) viscosity index of about 135-140, preferably 140 or
higher, as measured by ASTM D2270 test.
[0008] (b) pour point of about -35 C to -40 C, preferably -40 C or
lower, as measure by ASTM D97 test.
[0009] (c) Brookfield viscosity at -20 F of about 6500 cP or lower,
preferably 6200 cP or lower, as measured by ASTM D2983 test.
[0010] As an alternative to traditional Group 1 mineral oils and to
special PAO base oils, high viscosity index Group III base oils
would be expected to be usable in a wide-temperature hydraulic oil
application. Group III base stock may be used without added
solvent-refined naphthenic base stock, but generally continues to
be formulated with viscosity modifier and pour point
depressant.
[0011] Tests used in describing lubricant compositions of this
invention are:
[0012] (a) CCS viscosity measured by Cold Cranking Simulator Test
(ASTM D5293);
[0013] (b) Noack volatility (or evaporative loss) measured by
CEC-L-40-A-93;
[0014] (c) Viscosity index (VI) measured by ASTM D2270;
[0015] (d) Theoretical viscosity calculated by Walther-MacCoull
equation (ASTM D341 appendix 1);
[0016] (e) Kinematic viscosity measured by ASTM D445
[0017] (f) Pour point as measured by ASTM D5950.
[0018] (g) Scanning Brookfield Viscosity as measured by ASTM
D5133
[0019] (h) Brookfield Viscosity as measured by ASTM D2983.
[0020] (i) ISO viscosity as defined by the viscosity grade
classification in ISO 3448.
[0021] The inventors note that the Walther-MacCaull equation of
ASTM D341 computes a theoretic kinematic viscosity, while the CCS
reports an absolute viscosity. To compute the ratio as used herein,
the inventors converted the Walther-MacCaull viscosity as per
equation (I).
Theoretical viscosity@T.sub.1(.degree. C.)=Walther-MacCaull
Calculated Kinematic Viscosity@T.sub.1(.degree. C.).times.Density
at T.sub.1(.degree. C.) (I)
[0022] where T.sub.1 is the desired temperature.
[0023] The density at -35.degree. C. is estimated from the density
at 20.degree. C. using well-known formula. See, e.g., A. Bondi,
"Physical Chemistry of Lubricating Oils", 1951, p. 5.
[0024] A base stock (as opposed to a base oil and a lubricant
composition) is defined as a hydrocarbon stream produced by a
single manufacturer to the same specifications (independent of feed
source or manufacturers location) and that is identified by a
unique formula, product identification number, or both. Base stocks
may be manufactured using a variety of different processes
including but not limited to distillation, solvent refining,
hydrogen processing, oligomerization, esterification, and
rerefining. Rerefined stock shall be substantially free from
materials introduced through manufacturing, contamination or
previous use. A base stock slate is a product line of base stocks
that have different viscosities but are in the same base stock
grouping and from the same manufacturer. A base oil is the base
stock or blend of base stocks used in formulated lubricant
compositions. A lubricant composition may be a base stock, a base
oil, either alone or mixed with other stocks, oils or functional
additives.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 graphically compares the measured CCS viscosities
against the predicted Walther-MacCoull viscosities at various
temperatures.
[0026] FIG. 2 graphically illustrates the viscosity versus Noack
volatility profiles for various oils.
[0027] FIG. 3 graphically compares the kinematic viscosity versus
CCS viscosity for various inventive oils and comparative
examples.
SUMMARY OF THE INVENTION
[0028] This invention relates to functional fluids which
incorporate base stocks and base oils that achieve improved
viscosity performance at low temperatures (about -25 C or lower).
The present invention also relates to funtional fluids which
comprise a base oil derived from waxy hydrocarbon feedstocks,
either from natural or, mineral, or synthetic sources (e.g.
Fischer-Tropsch-type processes). This invention also relates to
processes or methods to make such functional fluids.
[0029] More specifically, this invention relates to functional
fluids having an unexpectedly advantageous wide-temperature
viscosity profile and comprising novel base stocks and base oils
with improved low-temperature fluidity (as described by a ratio of
measured-to-theoretical high-shear/low-temperature viscosity at -30
C or lower). In addition, this invention relates to functional
fluids that are surprisingly useful as hydraulic oils having
improved low-temperature viscosity as measured by Brookfield
viscosity at -20 F or lower. The beneficial characteristics of good
low-temperature fluidity uniquely differentiate the base stocks and
base oils incorporated into this invention from other similar Group
III base oils, and further differentiate the lubricant compositions
and functional fluids of this invention from other Group III-based
compositions.
[0030] More specifically, this invention encompasses a functional
fluid which incorporates base stocks that have the surprising and
unexpected simultaneous combination of properties of:
[0031] (a) viscosity index (VI) of 130 or greater,
[0032] (b) a pour point of -10 C or lower,
[0033] (c) a ratio of measured-to-theoretical low-temperature
viscosity equal to 1.2 or less, at a temperature of -30 C or lower,
where the measured viscosity is cold-crank simulator viscosity and
where theoretical viscosity is calculated at the same temperature
using the Walther-MacCoull equation.
[0034] The base oil compositions incorporated into this invention
encompass not only individual base stocks as manufactured, but also
mixtures or blends of two or more base stocks and/or base oils such
that the resulting mixture or blend satisfies the base stock
requirements of this invention. The base oil compositions of this
invention encompass a range of useful viscosities, with base oil
kinematic viscosity at 100 C of about 1.5 cSt to 8.5 cSt,
preferably about 2 cSt to 8 cSt, and more preferably about 3 cSt to
7.5 cSt. The base oils of this invention encompasses a range of
useful pour points, with pour points of about -10 C to greater than
-30 C, preferably about -12 C to greater than -30 C, and more
preferably about -14 C to greater than -30 C. In some instances,
the pour point may range from -18 C to -30 C and may further range
from -20 C to -30 C.
[0035] Preferably, the base stocks and base oils incorporated into
this invention as used herein will have a measured-to-theoretical
low-temperature viscosity of about 0.8 to about 1.2 at a
temperature of -30 C or lower, where the measured viscosity is
cold-crank simulator viscosity and where theoretical viscosity is
calculated at the same temperature using the Walther-MacCoull
equation
[0036] Surprisingly the low measured-to-theoretical viscosity
ratio, which distinguishes one unexpected performance advantage of
the base stocks and base oils of this invention, can also be
expected to be observed at temperatures below -35 C, for example
down to -40 C or even lower. Thus at these low temperatures, actual
viscosity of novel base stocks and base oils described herein would
be expected to approach the desired, ideal, theoretical viscosity,
while comparative base stocks and base oils would be expected to
deviate even more strongly away from theoretical viscosity (i.e. to
higher measured-to-theoretical viscosity ratios).
[0037] Additionally, the novel base stocks and base oils
incorporated into this invention may have the following
properties:
[0038] (a) saturates content of at least 90 wt %, and
[0039] (b) a sulfur content of 0.03 wt. % or less
[0040] Viscosity index of the novel base stocks and base oils
incorporated into this invention may be 130 or greater, or
preferably 135 or greater and in some instances, 140 or greater.
The desired pour point of the novel base stocks and base oils
incorporated into this invention is about -10 C or lower, or
preferably -12 C or lower, or in some instances more preferably -14
C or lower. In some instances the pour point may be -18 or lower
and more preferably, -20 C and lower. For the novel base stocks and
base oils incorporated into this invention, the desired
measured-to-theoretical ratio of low-temperature cold cranking
simulator (CCS) viscosity equals about 1.2 or less, or preferably
about 1.16 or less, or more preferably about 1.12 or less. For the
low-temperature viscosity profiles of the novel base stocks and
base oils incorporated into this invention, the desired novel base
stocks and base oils incorporated into this invention have CCS
viscosity @-35 C of less than 5500 cP, or preferably less than 5200
cP, or in some instances more preferably less than 5000 cP.
[0041] The novel base stocks and base oils described herein may be
used with other lubricant base stocks and base oils or co-base
stocks and co-base oils in formulated lubricant compositions or
functional fluids. In some instances, the highly advantageous
low-temperature (-30 C or lower) properties of these novel base
stocks and base oils incorporated into this invention can
beneficially improve the performance of lubricants and lubricant
compositions or functional fluids at concentrations of 20 wt % or
greater of the total base stocks and base oils contained in such
compositions. Preferably, the novel base stocks and base oils
incorporated into this invention may be used in combination with
other individual base stocks and base oils to gain significant
low-temperature performance benefits in finished lubricant
compositions or functional fluids. More preferably, the base stocks
and base oils may be used at 40 wt % or more of the total base
stocks and base oils contained in formulated lubricant compositions
or functional fluids, without detracting from the elements of this
invention. And in certain instances, the base oil(s) may be most
preferably used at 50 wt % or more of the total base stocks and
base oils, or even 70 wt % or more of the total base stocks and
base oils in finished lubricant compositions or functional
fluids.
[0042] The novel base stocks and base oils incorporated into the
present invention may be produced by:
[0043] (a) hydrotreating a feedstock having a wax content of at
least about 50 wt. %, based on feedstock, with a hydrotreating
catalyst under effective hydrotreating conditions such that less
than 5 wt. % of the feedstock is converted to 650 F (343 C) minus
products to produce a hydrotreated feedstock whose VI increase is
less than 4 greater than the VI of the feedstock;
[0044] (b) stripping or distilling the hydrotreated feedstock to
separate gaseous from liquid product; and
[0045] (c) hydrodewaxing the liquid product with a dewaxing
catalyst which is at least one of ZSM-22, ZSM-23, ZSM-35, ZSM-48,
ZSM-57, ferrierite, ECR-42, ITQ-13, MCM-68, MCM-71, beta, fluorided
alumina, silica-alumina or fluorided silica alumina under
catalytically effective hydrodewaxing conditions wherein the
dewaxing catalyst contains at least one Group 9 or Group 10 noble
metal, and
[0046] (d) optionally, hydrofinishing the product from step (c)
with a mesoporous hydrofinishing catalyst from the M41S family
under hydrofinishing conditions.
[0047] Another embodiment of this invention relates to a method of
making lubricants and lubricant compositions or functional fluids
that comprise novel base stocks and base oils incorporated into
this invention that have significant performance benefits in
reduced low-temperature viscosity, for example in hydraulic
oils.
DETAILED DESCRIPTION OF THE INVENTION
[0048] This invention relates to novel lubricants and lubricant
compositions comprising novel base stocks and base oils, and to
methods for optimizing lubrication performance under both
low-temperature and high-temperature conditions. The lubricant
compositions of this invention comprise base stocks and base oils
having an unexpectedly advantageous combination of high viscosity
index, and good low-temperature fluidity (as described by
low-temperature Brookfield viscosity). These lubricant compositions
are found to be useful as hydraulic oils and have surprisingly
advantageous combination of performance under both wide temperature
conditions, i.e. low-temperature and high-temperature
conditions.
[0049] Surprisingly, lubricants comprising base stocks of this
invention were found to demonstrate superior low-temperature
viscosity performance as measured by Brookfield viscosity at -20 F
or lower. In addition, inventive functional fluids comprising
exclusively the novel inventive base stocks recited herein
unexpectedly achieve superior Brookfield viscosity performance
results with no added viscosity modifier. This represents and
unexpected and novel alternative solution to the problem of
balancing good low-temperature viscosity with good high-temperature
viscosity in wide-temperature applications, such as, for example
wide-temperature hydraulic oils.
[0050] In addition, improvements in Brookfield viscosity
performance are demonstrated by the inventive functional fluids
recited herein even in cases where a more traditional formulation
strategy is used, i.e. combining lower viscosity base stocks or
base oils with a viscosity modifier. For example, in hydraulic oil
compositions comprising the novel base stocks and base oils
described herein, improved Brookfield viscosity at -20 F or lower
was found, and was significantly better than the Brookfield
viscosity of compositions formulated with currently available Group
III base stocks.
[0051] Functional fluids comprising the novel base stocks and base
oils described herein may be formulated to obtain finished
lubricant products having a range of useful ISO viscosity grades
(according to ISO 3448), from about ISO 2 to about ISO 1500.
Specifically, hydraulic oil compositions comprising these novel
base stocks and base oils incorporated into this invention may have
useful ISO viscosity grades of from about ISO 10 to ISO 150,
preferably from about ISO 15 to ISO 100, more preferably from about
ISO 22 to ISO 100, and in some instances most preferably ISO 32 to
ISO 68.
[0052] The inventive functional fluids comprising the novel base
stocks and base oils described herein have unexpectedly good
low-temperature viscosity as measured by the Brookfield viscosity
test (ASTM D2983). This result is unanticipated because the CCS
viscosities used in describing the novel base stocks of this
invention are not predictive of Brookfield viscosities found for
the corresponding formulated lubricant compositions. CCS viscosity
and Brookfield viscosity are sensitive to different low-temperature
base stock performance mechanisms, with CCS viscosity and
Brookfield viscosity being determined under differing shear
conditions.
[0053] One embodiment of this invention encompasses novel
functional fluids having improved Brookfield viscosity at -20 F or
lower and that may be advantageously used in wide-temperature
lubricant applications, such as, for example hydraulic oils.
[0054] The high viscosity index base stocks incorporated into this
invention have superior low-temperature performance when compared
to other high viscosity index base stocks. The difference in
performance is most critical in the temperature range below -30 C,
where conventional high viscosity index Group III base stocks
deviate significantly from the theoretical viscosity. To
illustrate, measured low-temperature CCS viscosity of comparative
conventional high viscosity index Group III base stocks tends to
deviate to higher viscosity values than that predicted
(Walther-MacCoull equation) for the expected theoretical viscosity
of the same base stocks at low temperatures (FIG. 1).
[0055] The novel base stocks and base oils described herein
surprisingly demonstrate the more ideal and highly desirable
performance predicted by the theoretical viscosity behavior of base
stocks and base oils, as described according to the
Walther-MacCoull equation (ASTM D341 appendix). In addition, the
novel base stocks and base oils incorporated into this invention
are found to be surprisingly different from available commercial
Group III base oil regarding the ratio of measured-to-theoretical
low-temperature viscosity, where actual viscosity is measured as
cold cranking simulator (CCS) viscosity at temperatures of -30 C or
lower, and where theoretical viscosity derives from the
Walther-MacCoull equation (ASTM D341, appendix) at the same
temperature as the measured CCS viscosity. It has similarly being
observed that these novel base stocks have a much lower
scanning-Brookfield viscosity (ASTM D5133) values at low
temperature (below -20 C). CCS viscosity is measured under high
sheer conditions, whereas scanning Brookfield viscosity is measured
under low sheer conditions.
[0056] The novel base stocks and base oils described herein have
the unique and highly desirable characteristic of a
measured-to-theoretical viscosity ratio of 1.2 or lower, preferably
1.16 or lower, and in many instances more preferably 1.12 or lower.
Base stocks and base oils having measured-to-theoretical viscosity
ratios of less than about 1.2 and with ratios approaching 1.0 are
highly desirable, because lower ratios indicate significant
advantages in low-temperature performance and operability. The
currently available Group III base stocks and base oils, however,
have characteristic measured-to-theoretical viscosity ratios of 1.2
and higher, indicating poorer base oil low-temperature viscosity
and operability. In some instances, it is preferred to have the
measured-to-theoretical viscosity ratio be between about 0.8 and
about 1.2.
[0057] In one embodiment of this invention, the novel base stocks
and base oils incorporated into this invention have the surprising
and unexpected simultaneous combination of properties of:
[0058] (a) viscosity index (VI) of 130 or greater,
[0059] (b) a pour point of -1.degree. C. or lower,
[0060] (c) a ratio of measured-to-theoretical low-temperature
viscosity equal to 1.2 or less, at a temperature of -30 C or lower,
where the measured viscosity is cold-crank simulator viscosity and
where theoretical viscosity is calculated at the same temperature
using the Walther-MacCoull equation.
[0061] Additionally, the novel base stocks and base oils described
herein may also have the following properties:
[0062] (a) saturates content of at least 90 wt %, and
[0063] (b) a sulfur content of 0.03 wt. % or less.
[0064] As used herein, the term lubricant includes, but is not
limited to, lubricant compositions, formulated lubricant
compositions, lubes, functional fluids, lube products, lube oils,
finished lubes, finished lubricants, lubricating oils, greases and
the like.
[0065] This invention also encompasses functional fluids comprising
the inventive base oil compositions with the properties:
[0066] (a) a viscosity index (VI) of 130 or greater,
[0067] (b) a pour point of -10 C or lower,
[0068] (c) a ratio of measured-to-theoretical low-temperature
viscosity equal to 1.2 or less, at a temperature of -30 C or lower,
where the measured viscosity is cold-crank simulator viscosity and
where theoretical viscosity is calculated at the same temperature
using the Walther-MacCoull equation.
[0069] In some instances, it is preferred to have the
measured-to-theoretical viscosity ratio be between about 0.8 and
about 1.2.
[0070] One embodiment of this invention encompasses functional
fluids having improved Brookfield viscosity at -20 F or lower
comprising the inventive base stock and at least one performance
additive. Another embodiment of this invention encompasses a
functional fluid having improved Brookfield viscosity at -20 F or
lower comprising base stocks of this invention in combination with
one or more additional base stocks, and at least one performance
additive. A further embodiment of this invention encompasses a
functional fluid having improved Brookfield viscosity at -20 F or
lower comprising base stocks of this invention without the use of
any added viscosity modifier.
[0071] Another embodiment of this invention encompasses an
hydraulic oil having improved Brookfield viscosity at -20 F or
lower and comprising the novel base stocks described herein. An
additional embodiment of this invention encompasses a method for
improving the Brookfield viscosity of functional fluids using the
novel base oils recited herein.
[0072] Other embodiments of this invention relate to methods of (a)
making functional fluids useful as wide-temperature hydraulic oils
comprising the novel base stocks recited herein, and (b) making
formulated functional fluids comprising the novel base oils recited
herein with such compositions or fluids having improved
low-temperature Brookfield viscosity at -20 F or lower.
[0073] Another embodiment encompasses a formulated lubricant
composition or functional fluid having improved Brookfield
viscosity at -20 F or lower comprising the novel base stocks
recited herein, with said functional fluids having a viscosity
index of about 135 or higher, preferably 140 or higher.
[0074] Another embodiment encompasses a functional fluid having
improved Brookfield viscosity at -20 F or lower comprising the
novel base stocks recited herein, functional fluids having a pour
point of about -35 C or lower, preferably about -40 C or lower.
[0075] Another embodiment encompasses a formulated lubricant
composition or functional fluid having improved Brookfield
viscosity at -20 F or lower comprising the novel base stocks
recited herein, with said lubricant compositions or functional
fluids having a Brookfield viscosity at -20 F of about 4000 cP or
lower, preferably about 28000 cP or lower, more preferably 6500 cP
or lower, and even more preferably about 6200 cP or lower.
[0076] Products which incorporate the novel base stocks or base
oils recited herein clearly have an advantage over other similar
products made from conventional Group III base stocks. One
embodiment of this invention is a formulated lubricant composition
or functional fluids comprising novel base stocks and base oils
described herein in combination with one or more additional co-base
stocks and base oils. Another embodiment of this invention is a
formulated lubricant composition or functional fluid comprising the
novel base stocks and base oils described herein in combination
with one or more performance additives.
[0077] Performance additives as used in this invention may
encompass, for example, individual additives as components,
combinations of one or more individual additives or components as
additive systems, combinations of one or more additives with one or
more suitable diluent oils as additive concentrates or packages.
Additive concentrate encompasses component concentrates as well as
additive packages. Often in making or formulating lubricant
compositions or functional fluids, viscosity modifiers or viscosity
index improvers may be used individually as components or
concentrates, independent of the use of other performance additives
in the form of components, concentrates, or packages. The amount
and type of performance additives that may be combined with the
base oils of this invention are limited such that the lubricant
composition comprising this total base oil mixture and one or more
performance additives simultaneously meet the low-temperature
Brookfield viscosity at -20 F or lower and high-temperature
kinematic viscosity at 40 C or above that are useful for
wide-temperature hydraulic oils applications.
[0078] This invention is surprisingly advantageous in applications
where low-temperature properties are important to the performance
of the finished lube or functional fluid. The novel base stocks and
base oils described herein may be advantageously used in many of
the following applications, for example hydraulic fluids,
compressor oils, turbine oils, circulating oils, gear oils, paper
machine oils, industrial oils, automotive oils, manual transmission
fluids, automatic transmission fluids, drive train fluids, engine
oils, gas engine oils, aviation piston oils, diesel oils, marine
oils, greases, and the like.
[0079] Process
[0080] The products that derive from the processes of this
invention demonstrate not only unique combinations of physical
properties, but demonstrate unique compositional properties that
distinguish and differentiate them from available commercial
products. Thus, the novel base stocks and base oils described
herein derived from the processes recited herein are expected to
have unique chemical, compositional, molecular, and structural
features that uniquely define the base stocks and base oils of this
invention.
[0081] The novel base stocks and base oils described herein are
made according to processes comprising the conversion of waxy
feedstocks to produce oils of lubricating viscosity having high
viscosity indices and produced in high yields. Thus, one may obtain
base stocks and base oils or base stocks having VIs of at least
130, preferably at least 135, more preferably at least 140, and
having excellent low-temperature properties. Base stocks made
according to these processes meet the requirements of a Group III
base stock and can be prepared in high yields while at the same
time possessing excellent properties such as high VI and low pour
point.
[0082] The waxy feedstock used in these processes may derive from
natural or mineral or synthetic sources. The feed to this process
may have a waxy paraffins content of at least 50% by weight,
preferably at least 70% by weight, and more preferably at least 80%
by weight. Preferred synthetic waxy feedstocks generally have waxy
paraffins content by weight of at least 90 wt %, often at least 95
wt %, and in some instances at least 97 wt %. In addition, the waxy
feed stock used in these processes to make the novel base stocks
and base oils described herein may comprise one or more individual
natural, mineral, or synthetic waxy feedstocks, or any mixture
thereof.
[0083] In addition, feedstocks to these processes may be either
taken from conventional mineral oils, or synthetic processes. For
example, synthetic processes may include GTL (gas-to-liquids) or FT
(Fischer-Tropsch) hydrocarbons produced by such processes as the
Fischer-Tropsch process or the Kolbel-Englehardt process. Many of
the preferred feedstocks are characterized as having predominantly
saturated (paraffinic) compositions.
[0084] In more detail, the feedstock used in the process of the
invention are wax-containing feeds that boil in the lubricating oil
range, typically having a 10% distillation point greater than 650 F
(343 C), measured by ASTM D 86 or ASTM 2887, and are derived from
mineral or synthetic sources. The wax content of the feedstock is
at least about 50 wt. %, based on feedstock and can range up to 100
wt. % wax. The wax content of a feed may be determined by nuclear
magnetic resonance spectroscopy (ASTM D5292), by correlative ndM
methods (ASTM D3238) or by solvent means (ASTM D3235). The waxy
feeds may be derived from a number of sources such as natural or
mineral or synthetic. In particular, waxy feeds may include, for
example, oils derived from solvent refining processes such as
raffinates, partially solvent dewaxed oils, deasphalted oils,
distillates, vacuum gas oils, coker gas oils, slack waxes, foots
oils and the like, and Fischer-Tropsch waxes. Preferred feeds are
slack waxes and Fischer-Tropsch waxes. Slack waxes are typically
derived from hydrocarbon feeds by solvent or propane dewaxing.
Slack waxes contain some residual oil and are typically deoiled.
Foots oils are derived from deoiled slack waxes. The
Fischer-Tropsch synthetic process prepares Fischer-Tropsch waxes.
Non limiting examples of suitable waxy feedstocks include Paraflint
80 (a hydrogenated Fischer-Tropsch wax) and Shell MDS Waxy
Raffinate (a hydrogenated and partially isomerized middle
distillate synthesis waxy raffinate.)
[0085] Feedstocks may have high contents of nitrogen- and
sulfur-contaminants. Feeds containing up to 0.2 wt. % of nitrogen,
based on feed and up to 3.0 wt. % of sulfur can be processed in the
present process. Feeds having a high wax content typically have
high viscosity indexes of up to 200 or more. Sulfur and nitrogen
contents may be measured by standard ASTM methods D5453 and D4629,
respectively.
[0086] For feeds derived from solvent extraction, the high boiling
petroleum fractions from atmospheric distillation are sent to a
vacuum distillation unit, and the distillation fractions from this
unit are solvent extracted. The residue from vacuum distillation
may be deasphalted. The solvent extraction process selectively
dissolves the aromatic components in an extract phase while leaving
the more paraffinic components in a raffinate phase. Naphthenes are
distributed between the extract and raffinate phases. Typical
solvents for solvent extraction include phenol, furfural and
N-methyl pyrrolidone. By controlling the solvent to oil ratio,
extraction temperature and method of contacting distillate to be
extracted with solvent, one can control the degree of separation
between the extract and raffinate phases.
[0087] Hydrotreating
[0088] For hydrotreating, the catalysts are those effective for
hydrotreating such as catalysts containing Group 6 metals (based on
the IUPAC Periodic Table format having Groups from 1 to 18), Groups
8-10 metals, and mixtures thereof. Preferred metals include nickel,
tungsten, molybdenum, cobalt and mixtures thereof. These metals or
mixtures of metals are typically present as oxides or sulfides on
refractory metal oxide supports. The mixture of metals may also be
present as bulk metal catalysts wherein the amount of metal is 30
wt. % or greater, based on catalyst. Suitable metal oxide supports
include oxides such as silica, alumina, silica-aluminas or titania,
preferably alumina. Preferred aluminas are porous aluminas such as
gamma or beta. The amount of metals, either individually or in
mixtures, ranges from about 0.5 to 35 wt. %, based on the catalyst.
In the case of preferred mixtures of groups 9-10 metals with group
6 metals, the groups 9-10 metals are present in amounts of from 0.5
to 5 wt. %, based on catalyst and the group 6 metals are present in
amounts of from 5 to 30 wt. %. The amounts of metals may be
measured by atomic absorption spectroscopy, inductively coupled
plasma-atomic emission spectrometry or other methods specified by
ASTM for individual metals.
[0089] The acidity of metal oxide supports can be controlled by
adding promoters and/or dopants, or by controlling the nature of
the metal oxide support, e.g., by controlling the amount of silica
incorporated into a silica-alumina support. Examples of promoters
and/or dopants include halogen, especially fluorine, phosphorus,
boron, yttria, rare-earth oxides and magnesia. Promoters such as
halogens generally increase the acidity of metal oxide supports
while mildly basic dopants such as yttria or magnesia tend to
decrease the acidity of such supports.
[0090] Hydrotreating conditions include temperatures of from 150 to
400.degree. C., preferably 200 to 350.degree. C., a hydrogen
partial pressure of from 1480 to 20786 kPa (200 to 3000 psig),
preferably 2859 to 13891 kPa (400 to 2000 psig), a space velocity
of from 0.1 to 10 liquid hourly space velocity (LHSV), preferably
0.1 to 5 LHSV, and a hydrogen to feed ratio of from 89 to 1780
m.sup.3/m.sup.3 (500 to 28000 scf/B), preferably 178 to 890
m.sup.3/m.sup.3.
[0091] Hydrotreating reduces the amount of nitrogen- and
sulfur-containing contaminants to levels which will not
unacceptably affect the dewaxing catalyst in the subsequent
dewaxing step. Also, there may be certain polynuclear aromatic
species which will pass through the present mild hydrotreating
step. These contaminants, if present, will be removed in a
subsequent hydrofinishing step.
[0092] During hydrotreating, less than 5 wt. % of the feedstock,
preferably less than 3 wt. %, more preferably less than 2 wt. %, is
converted to 650.degree. F. (343.degree. C.) minus products to
produce a hydrotreated feedstock whose VI increase is less than 4,
preferably less than 3, more preferably less than 2 greater than
the VI of the feedstock. The high wax contents of the present feeds
results in minimal VI increase during the hydrotreating step.
[0093] The hydrotreated feedstock may be passed directly to the
dewaxing step or preferably, stripped to remove gaseous
contaminants such as hydrogen sulfide and ammonia prior to
dewaxing. Stripping can be by conventional means such as flash
drums or fractionators
[0094] Dewaxing Catalyst
[0095] The dewaxing catalyst may be either crystalline or
amorphous. Crystalline materials are molecular sieves that contain
at least one 10 or 12 ring channel and may be based on
aluminosilicates (zeolites) or on silicoaluminophosphates (SAPOs).
Zeolites used for oxygenate treatment may contain at least one 10
or 12 channel. Examples of such zeolites include ZSM-22, ZSM-23,
ZSM-35, ZSM-48, ZSM-57, ferrierite, ITQ-13, MCM-68 and MCM-71.
Examples of aluminophosphates containing at least one 10 ring
channel include ECR-42. Examples of molecular sieves containing 12
ring channels include zeolite beta, and MCM-68. The molecular
sieves are described in U.S. Pat. Nos. 5,246,566, 5,282,958,
4,975,177, 4,397,827, 4,585,747, 5,075,269 and 4,440,871. MCM-68 is
described in U.S. Pat. No. 6,310,265. MCM-71 and ITQ-13 are
described in PCT published applications WO 0242207 and WO 0078677.
ECR-42 is disclosed in U.S. Pat. No. 6,303,534. Preferred catalysts
include ZSM-48, ZSM-22 and ZSM-23. Especially preferred is ZSM-48.
The molecular sieves are preferably in the hydrogen form. Reduction
can occur in situ during the dewaxing step itself or can occur ex
situ in another vessel.
[0096] Amorphous dewaxing catalysts include alumina, fluorided
alumina, silica-alumina, fluorided silica-alumina and
silica-alumina doped with Group 3 metals. Such catalysts are
described for example in U.S. Pat. Nos. 4,900,707 and
6,383,366.
[0097] The dewaxing catalysts are bifunctional, i.e., they are
loaded with a metal hydrogenation component, which is at least one
Group 6 metal, at least one Group 8-10 metal, or mixtures thereof.
Preferred metals are Groups 9-10 metals. Especially preferred are
Groups 9-10 noble metals such as Pt, Pd or mixtures thereof (based
on the IUPAC Periodic Table format having Groups from 1 to 18).
These metals are loaded at the rate of 0.1 to 30 wt. %, based on
catalyst. Catalyst preparation and metal loading methods are
described for example in U.S. Pat. No. 6,294,077, and include for
example ion exchange and impregnation using decomposable metal
salts. Metal dispersion techniques and catalyst particle size
control are described in U.S. Pat. No. 5,282,958. Catalysts with
small particle size and well dispersed metal are preferred.
[0098] The molecular sieves are typically composited with binder
materials which are resistant to high temperatures which may be
employed under dewaxing conditions to form a finished dewaxing
catalyst or may be binderless (self bound). The binder materials
are usually inorganic oxides such as silica, alumina,
silica-aluminas, binary combinations of silicas with other metal
oxides such as titania, magnesia, thoria, zirconia and the like and
tertiary combinations of these oxides such as silica-alumina-thoria
and silica-alumina magnesia. The amount of molecular sieve in the
finished dewaxing catalyst is from 10 to 100, preferably 35 to 100
wt. %, based on catalyst. Such catalysts are formed by methods such
spray drying, extrusion and the like. The dewaxing catalyst may be
used in the sulfided or unsulfided form, and is preferably in the
sulfided form.
[0099] Dewaxing conditions include temperatures of from
250-400.degree. C., preferably 275 to 350.degree. C., pressures of
from 791 to 20786 kPa (100 to 3000 psig), preferably 1480 to 17339
kPa (200 to 2500 psig), liquid hourly space velocities of from 0.1
to 10 hr.sup.-1, preferably 0.1 to 5 hr.sup.-1 and hydrogen treat
gas rates from 45 to 1780 m.sup.3/m.sup.3 (250 to 28000 scf/B),
preferably 89 to 890 m.sup.3/m.sup.3 (500 to 5000 scf/B).
[0100] Hydrofinishing
[0101] At least a portion of the product from dewaxing is passed
directly to a hydrofinishing step without disengagement. It is
preferred to hydrofinish the product resulting from dewaxing in
order to adjust product qualities to desired specifications.
Hydrofinishing is a form of mild hydrotreating directed to
saturating any lube range olefins and residual aromatics as well as
to removing any remaining heteroatoms and color bodies. The post
dewaxing hydrofinishing is usually carried out in cascade with the
dewaxing step. Generally the hydrofinishing will be carried out at
temperatures from about 150.degree. C. to 350.degree. C.,
preferably 180.degree. C. to 250.degree. C. Total pressures are
typically from 2859 to 20786 kPa (about 400 to 3000 psig). Liquid
hourly space velocity is typically from 0.1 to 5 LHSV (hr.sup.-1),
preferably 0.5 to 3 hr.sup.-1 and hydrogen treat gas rates of from
44.5 to 1780 m.sup.3/m.sup.3 (250 to 10,000 scf/B).
[0102] Hydrofinishing catalysts are those containing Group 6 metals
(based on the IUPAC Periodic Table format having Groups from 1 to
18), Groups 8-10 metals, and mixtures thereof. Preferred metals
include at least one noble metal having a strong hydrogenation
function, especially platinum, palladium and mixtures thereof. The
mixture of metals may also be present as bulk metal catalysts
wherein the amount of metal is 30 wt. % or greater based on
catalyst. Suitable metal oxide supports include low acidic oxides
such as silica, alumina, silica-aluminas or titania, preferably
alumina. The preferred hydrofinishing catalysts for aromatics
saturation will comprise at least one metal having relatively
strong hydrogenation function on a porous support. Typical support
materials include amorphous or crystalline oxide materials such as
alumina, silica, and silica-alumina. The metal content of the
catalyst is often as high as about 20 weight percent for non-noble
metals. Noble metals are usually present in amounts no greater than
about 1 wt. %.
[0103] The hydrofinishing catalyst is preferably a mesoporous
material belonging to the M41S class or family of catalysts. The
M41S family of catalysts are mesoporous materials having high
silica contents whose preparation is further described in J. Amer.
Chem. Soc., 1992, 114, 10834. Examples included MCM-41, MCM-48 and
MCM-50. Mesoporous refers to catalysts having pore sizes from 15 to
100 .ANG.. A preferred member of this class is MCM-41 whose
preparation is described in U.S. Pat. No. 5,098,684. MCM-41 is an
inorganic, porous, non-layered phase having a hexagonal arrangement
of uniformly-sized pores. The physical structure of MCM-41 is like
a bundle of straws wherein the opening of the straws (the cell
diameter of the pores) ranges from 15 to 100 Angstroms. MCM-48 has
a cubic symmetry and is described for example is U.S. Pat. No.
5,198,203 whereas MCM-50 has a lamellar structure. MCM-41 can be
made with different size pore openings in the mesoporous range. The
mesoporous materials may bear a metal hydrogenation component which
is at least one of Group 8, Group 9 or Group 10 metals. Preferred
are noble metals, especially Group 10 noble metals, most preferably
Pt, Pd or mixtures thereof.
[0104] Generally the hydrofinishing will be carried out at
temperatures from about 150.degree. C. to 350.degree. C.,
preferably 180.degree. C. to 250.degree. C. Total pressures are
typically from 2859 to 20786 kPa (about 400 to 3000 psig). Liquid
hourly space velocity is typically from 0.1 to 5 LHSV (hr.sup.-1),
preferably 0.5 to 3 hr.sup.-1 and hydrogen treat gas rates of from
44.5 to 1780 m.sup.3/m.sup.3 (250 to 10,000 scf/B).
[0105] In one embodiment, the present invention is directed to a
lubricant comprising at least one base stock with a VI of at least
130 produced by a process which comprises:
[0106] (1) hydrotreating a feedstock having a wax content of at
least about 60 wt. %, based on feedstock, with a hydrotreating
catalyst under effective hydrotreating conditions such that less
than 5 wt. % of the feedstock is converted to 650.degree. F.
(343.degree. C.) minus products to produce a hydrotreated feedstock
whose VI increase is less than 4 greater than the VI of the
feedstock;
[0107] (2) stripping the hydrotreated feedstock to separate gaseous
from liquid product; and
[0108] (3) hydrodewaxing the liquid product with a dewaxing
catalyst which is at least one of ZSM-48, ZSM-57, ZSM-23, ZSM-22,
ZSM-35, ferrierite, ECR-42, ITQ-13, MCM-71, MCM-68, beta, fluorided
alumina, silica-alumina or fluorided silica alumina under
catalytically effective hydrodewaxing conditions wherein the
dewaxing catalyst contains at least one Group 9 or Group 10 noble
metal.
[0109] Another embodiment of the present invention is directed to a
lubricant comprising at least one base stock with a VI of at least
130 produced by a process which comprises:
[0110] (1) hydrotreating a lubricating oil feedstock having a wax
content of at least about 50 wt. %, based on feedstock, with a
hydrotreating catalyst under effective hydrotreating conditions
such that less than 5 wt. % of the feedstock is converted to
650.degree. F. (343.degree. C.) minus products to produce a
hydrotreated feedstock to produce a hydrotreated feedstock whose VI
increase is less than 4 greater than the VI of the feedstock;
[0111] (2) stripping the hydrotreated feedstock to separate gaseous
from liquid product;
[0112] (3) hydrodewaxing the liquid product with a dewaxing
catalyst which is at least one of ZSM-22, ZSM-23, ZSM-35,
ferrierite, ZSM-48, ZSM-57, ECR-42, ITQ-13, MCM-68, MCM-71, beta,
fluorided alumina, silica-alumina or fluorided silica-alumina under
catalytically effective hydrodewaxing conditions wherein the
dewaxing catalyst contains at least one Group 9 or 10 noble metal;
and
[0113] (4) hydrofinishing the product from step (3) with a
mesoporous hydrofinishing catalyst from the M41S family under
hydrofinishing conditions.
[0114] Another embodiment of the present invention is directed to a
lubricant comprising at least one base stock with a VI of at least
130 produced by a process which comprises:
[0115] (1) hydrotreating a lubricating oil feedstock having a wax
content of at least about 60 wt. %, based on feedstock, with a
hydrotreating catalyst under effective hydrotreating conditions
such that less than 5 wt. % of the feedstock is converted to
650.degree. F. (343.degree. C.) minus products to produce a
hydrotreated feedstock to produce a hydrotreated feedstock whose VI
increase is less than 4 greater than the VI of the feedstock;
[0116] (2) stripping the hydrotreated feedstock to separate gaseous
from liquid product;
[0117] (3) hydrodewaxing the liquid product with a dewaxing
catalyst which is ZSM-48 under catalytically effective
hydrodewaxing conditions wherein the dewaxing catalyst contains at
least one Group 9 or 10 noble metal; and
[0118] (a) Optionally, hydrofinishing the product from step (3)
with MCM-41 under hydrofinishing conditions.
[0119] Additional details concerning the processes that make the
current invention may be found in co-pending application U.S. S No.
60/416,865 which is hereby incorporated by reference in its
entirety.
[0120] Base Stocks and Base Oils
[0121] A wide range of base stocks and base oils are known in the
art. Base stocks and base oils that may be used as co-base stocks
or co-base oils in combination with the base stocks and base oils
of the present invention are natural oils, mineral oils, and
synthetic oils. These lubricant base stocks and base oils may be
used individually or in any combination of mixtures with the
instant invention. Natural, mineral, and synthetic oils (or
mixtures thereof) may be used unrefined, refined, or rerefined (the
latter is also known as reclaimed or reprocessed oil). Unrefined
oils are those obtained directly from a natural, mineral, or
synthetic source and used without added purification. These include
shale oil obtained directly from retorting operations, petroleum
oil obtained directly from primary distillation, and ester oil
obtained directly from an esterification process. Refined oils are
similar to the oils discussed for unrefined oils except refined
oils are subjected to one or more purification steps to improve the
at least one lubricating oil property. One skilled in the art is
familiar with many purification processes. These processes include
for example solvent extraction, distillation, secondary
distillation, acid extraction, base extraction, filtration,
percolation, dewaxing, hydroisomerization, hydrocracking,
hydrofinishing, and others. Rerefined oils are obtained by
processes analogous to refined oils but using an oil that has been
previously used.
[0122] Groups I, II, III, IV and V are broad categories of base oil
stocks developed and defined by the American Petroleum Institute
(API Publication 1509; www.API.org) to create guidelines for
lubricant base stocks and base oils. Group I base stock generally
have a viscosity index of between about 80 to 120 and contains
greater than about 0.03 wt % sulfur and/or less than about 90%
saturates. Group II base stocks generally have a viscosity index of
between about 80 to 120, and contain less than or equal to about
0.03 wt % sulfur and greater than or equal to about 90% saturates.
Group III stock generally has a viscosity index greater than about
120 and contain less than or equal to about 0.03 wt % sulfur and
greater than about 90% saturates. Group IV includes
polyalphaolefins (PAO). Group V base stock includes base stocks not
included in Groups I-IV. The table below summarizes properties of
each of these five Groups.
1TABLE 1 API Classification of Base stocks and base oils Saturates
(wt %) Sulfur (wt %) Viscosity Index Group I <90 &/or
>0.03% & .gtoreq.80 & <120 Group II .gtoreq.90 &
.ltoreq.0.03% & .gtoreq.80 & <120 Group III .gtoreq.90
& .ltoreq.0.03% & .gtoreq.120 Group IV Polyalphaolefins
(PAO) Group V All other base stocks and base oils not included in
Groups I, II, III, or IV
[0123] Base stocks and base oils may be derived from many sources.
Natural oils include animal oils, vegetable oils (castor oil and
lard oil, for example), and mineral oils. In regard to animal and
vegetable oils, those possessing favorable thermal oxidative
stability can be used. Of the natural oils, mineral oils are
preferred. Mineral oils vary widely as to their crude source, for
example, as to whether they are paraffinic, naphthenic, or mixed
paraffinic-naphthenic. Oils derived from coal or shale are also
useful in the present invention. Natural oils vary also as to the
method used for their production and purification, for example,
their distillation range and whether they are straight run or
cracked, hydrorefined, or solvent extracted.
[0124] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
polymers or copolymer of hydrocarbyl-substituted olefins where
hydrocarbyl optionally contains 0, N, or S, for example).
Polyalphaolefin (PAO) oil base stocks are a commonly used synthetic
hydrocarbon oil. By way of example, PAOs derived from C8, C10, C12,
C14 olefins or mixtures thereof may be utilized. See U.S. Pat. Nos.
4,956,122; 4,827,064; and 4,827,073, which are incorporated herein
by reference in their entirety.
[0125] Group III and PAO base stocks and base oils are typically
available in a number of viscosity grades, for example, with
kinematic viscosity at 100 C of 4 cSt, 5 cSt, 6 cSt, 8 cSt, 10 cSt,
12 cSt, 40 cSt, 100 cSt, and higher, as well as any number of
intermediate viscosity grades. In addition, PAO base stocks and
base oils with high viscosity-index characteristics are available,
typically in higher viscosity grades, for example, with kinematic
viscosity at 100 C of 100 cSt to 3000 cSt or higher. The number
average molecular weights of the PAOs, which are known materials
and generally available on a major commercial scale from suppliers
such as ExxonMobil Chemical Company, Chevron-Phillips, BP-Amoco,
and others, typically vary from about 250 to about 3000. The PAOs
are typically comprised of relatively low molecular weight
hydrogenated polymers or oligomers of alphaolefins which include,
but are not limited to, C2 to about C32 alphaolefins with C8 to
about C16 alphaolefins, such as 1-octene, 1-decene, 1-dodecene and
the like, being preferred. The preferred polyalphaolefins are
poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures
thereof and mixed olefin-derived polyolefins. However, the dimers
of higher olefins in the range of C14 to C18 may be used to provide
low viscosity basestocks of acceptably low volatility. Depending on
the viscosity grade and the starting oligomer, the PAOs may be
predominantly trimers and tetramers of the starting olefins, with
minor amounts of the higher oligomers, having a viscosity range of
about 1.5 to 12 cSt. PAO base stocks and base oils may be used in
formulated lubricant composition or functional fluids either
individually or in any combination of two or more.
[0126] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as the Friedel-Crafts catalysts
including, for example, aluminum trichloride, boron trifluoride or
complexes of boron trifluoride with water, alcohols such as
ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods
disclosed by U.S. Pat. No. 4,149,178 or U.S. Pat. No. 3,382,291 may
be conveniently used herein. Other descriptions of PAO synthesis
are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363;
3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355;
4,956,122; and 5,068,487. The dimers of the C14 to C18 olefins are
described in U.S. Pat. No. 4,218,330. All of the aforementioned
patents are incorporated by reference herein in their entirety.
[0127] Other types of synthetic PAO base stocks and base oils
include high viscosity index lubricant fluids as described in U.S.
Pat. Nos. 4,827,064 and 4,827,073, which can be highly
advantageously used in combination with the base stocks and base
oils of this inventions, as well as with in the formulated
lubricant compositions or functions fluids of this same invention.
Other useful synthetic lubricating oils may also be utilized, for
example, those described in the work "Synthetic Lubricants",
Gunderson and hart, Reinhold Publ. Corp., New York, 1962, which is
incorporated in its entirety.
[0128] Other synthetic base stocks and base oils include
hydrocarbon oils that are derived from the oligomerization or
polymerization of low-molecular weight compounds whose reactive
group is not olefinic, into higher molecular weight compounds,
which may be optionally reacted further or chemically modified in
additional processes (e.g. isodewaxing, alkylation, esterification,
hydroisomerization, dewaxing, etc.) to give a base oil of
lubricating viscosity.
[0129] Hydrocarbyl aromatic base stocks and base oils are also
widely used in lubrication oils and functional fluids. In alkylated
aromatic stocks (hydrocarbyl aromatics, for example), the alkyl
substituents are typically alkyl groups of about 8 to 25 carbon
atoms, usually from about 10 to 18 carbon atoms and up to three
such substituents may be present, as described for the alkyl
benzenes in ACS Petroleum Chemistry Preprint 1053-1058, "Poly
n-Alkylbenzene Compounds: A Class of Thermally Stable and Wide
Liquid Range Fluids", Eapen et al, Phila. 1984. Tri-alkyl benzenes
may be produced by the cyclodimerization of 1-alkynes of 8 to 12
carbon atoms as described in U.S. Pat. No. 5,055,626. Other
alkylbenzenes are described in European Patent Application No.
168534 and U.S. Pat. No. 4,658,072. Alkylbenzenes are used as
lubricant basestocks, especially for low-temperature applications
(arctic vehicle service and refrigeration oils) and in papermaking
oils. They are commercially available from producers of linear
alkylbenzenes (LABs) such as Vista Chem. Co, Huntsman Chemical Co.,
Chevron Chemical Co., and Nippon Oil Co. The linear alkylbenzenes
typically have good low pour points and low temperature viscosities
and VI values greater than 100 together with good solvency for
additives. Other alkylated aromatics which may be used when
desirable are described, for example, in "Synthetic Lubricants and
High Performance Functional Fluids", Dressler, H., chap 5, (R. L.
Shubkin (Ed.)), Marcel Dekker, N.Y. 1993. Aromatic base stocks and
base oils may include, for example, hydrocarbyl alkylated
derivatives of benzene, naphthalene, biphenyls, di-aryl ethers,
di-aryl sulfides, di-aryl sulfones, di-aryl sulfoxides, di-aryl
methanes or ethanes or propanes or higher homologues, mono- or di-
or tri-aryl heterocyclic compounds containing one or more O, N, S,
or P.
[0130] The hydrocarbyl aromatics that can be used can be any
hydrocarbyl molecule that contains at least about 5% of its weight
derived from an aromatic moiety such as a benzenoid moiety or
naphthenoid moiety, or their derivatives. These hydrocarbyl
aromatics include alkyl benzenes, alkyl naphthalenes, alkyl
diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides,
alkylated bis-phenol A, alkylated thiodiphenol, and the like. The
aromatic can be mono-alkylated, dialkylated, polyalkylated, and the
like. The aromatic can be mono- or poly-functionalized. The
hydrocarbyl groups can also be comprised of mixtures of alkyl
groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl
groups and other related hydrocarbyl groups. The hydrocarbyl groups
can range from about C6 up to about C60 with a range of about C8 to
about C40 often being preferred. A mixture of hydrocarbyl groups is
often preferred. The hydrocarbyl group can optionally contain
sulfur, oxygen, and/or nitrogen containing substituents. The
aromatic group can also be derived from natural (petroleum)
sources, provided at least about 5% of the molecule is comprised of
an above-type aromatic moiety. Viscosities at 100 C of
approximately 3 cSt to about 50 cSt are preferred, with viscosities
of approximately 3.4 cSt to about 20 cSt often being more preferred
for the hydrocarbyl aromatic component. In one embodiment, an alkyl
naphthalene where the alkyl group is primarily comprised of
1-hexadecene is used. Other alkylates of aromatics can be
advantageously used. Naphthalene, for example, can be alkylated
with olefins such as octene, decene, dodecene, tetradecene or
higher, mixtures of similar olefins, and the like. Useful
concentrations of hydrocarbyl aromatic in a lubricant oil
composition can be about 2% to about 25%, preferably about 4% to
about 20%, and more preferably about 4% to about 15%, depending on
the application.
[0131] Other useful lubricant oil base stocks include wax isomerate
base stocks and base oils, comprising hydroisomerized waxy stocks
(e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker
bottoms, etc.), hydroisomerized Fischer-Tropsch waxes,
Gas-to-Liquids (GTL) base stocks and base oils, and other wax
isomerate hydroisomerized base stocks and base oils, or mixtures
thereof. Fischer-Tropsch waxes, the high boiling point residues of
Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with
very low sulfur content. The hydroprocessing used for the
production of such base stocks may use an amorphous
hydrocracking/hydroisomerization catalyst, such as one of the
specialized lube hydrocracking (LHDC) catalysts or a crystalline
hydrocracking/hydroisomerization catalyst, preferably a zeolitic
catalyst. For example, one useful catalyst is ZSM-48 as described
in U.S. Pat. No. 5,075,269. Processes for making
hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in
U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as
well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and
1,390,359. Particularly favorable processes are described in
European Patent Application Nos. 464546 and 464547. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172
and 4,943,672. Gas-to-Liquids (GTL) base stocks and base oils,
Fischer-Tropsch wax derived base stocks and base oils, and other
wax isomerate hydroisomerized (wax isomerate) base stocks and base
oils be advantageously used in the instant invention, and may have
useful kinematic viscosities at 100 C of about 3 cSt to about 50
cSt, preferably about 3 cSt to about 30 cSt, more preferably about
3.5 cSt to about 25 cSt, as exemplified by GTL4 with kinematic
viscosity of about 3.8 cSt at 100 C and a viscosity index of about
138. These Gas-to-Liquids (GTL) base stocks and base oils,
Fischer-Tropsch wax derived base stocks and base oils, and other
wax isomerate hydroisomerized base stocks and base oils may have
useful pour points of about -20 C or lower, and under some
conditions may have advantageous pour points of about -25 C or
lower, with useful pour points of about -30 C to about -40 C or
lower. Useful compositions of Gas-to-Liquids (GTL) base stocks and
base oils, Fischer-Tropsch wax derived base stocks and base oils,
and wax isomerate hydroisomerized base stocks and base oils are
recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for
example, and are incorporated herein in their entirety by
reference.
[0132] Gas-to-Liquids (GTL) base stocks and base oils,
Fischer-Tropsch wax derived base stocks and base oils, have a
beneficial kinematic viscosity advantage over conventional Group II
and Group III base stocks and base oils, which may be used as a
co-base stock or co-base oil with the instant invention.
Gas-to-Liquids (GTL) base stocks and base oils can have
significantly higher kinematic viscosities, up to about 20-50 cSt
at 100 C, whereas by comparison commercial Group II base stocks and
base oils can have kinematic viscosities, up to about 15 cSt at 100
C, and commercial Group III base stocks and base oils can have
kinematic viscosities, up to about 10 cSt at 100 C. The higher
kinematic viscosity range of Gas-to-Liquids (GTL) base stocks and
base oils, compared to the more limited kinematic viscosity range
of Group II and Group III base stocks and base oils, in combination
with the instant invention can provide additional beneficial
advantages in formulating lubricant compositions. Also, the
exceptionally low sulfur content of Gas-to-Liquids (GTL) base
stocks and base oils, and other wax isomerate hydroisomerized base
stocks and base oils, in combination with the low sulfur content of
suitable olefin oligomers and/or alkyl aromatics base stocks and
base oils, and in combination with the instant invention can
provide additional advantages in lubricant compositions where very
low overall sulfur content can beneficially impact lubricant
performance.
[0133] Alkylene oxide polymers and interpolymers and their
derivatives containing modified terminal hydroxyl groups obtained
by, for example, esterification or etherification are useful
synthetic lubricating oils. By way of example, these oils may be
obtained by polymerization of ethylene oxide or propylene oxide,
the alkyl and aryl ethers of these polyoxyalkylene polymers
(methyl-polyisopropylene glycol ether having an average molecular
weight of about 1000, diphenyl ether of polyethylene glycol having
a molecular weight of about 500-1000, and the diethyl ether of
polypropylene glycol having a molecular weight of about 1000 to
1500, for example) or mono- and polycarboxylic esters thereof (the
acidic acid esters, mixed C3-8 fatty acid esters, or the C13Oxo
acid diester of tetraethylene glycol, for example).
[0134] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of monocarboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0135] Particularly useful synthetic esters are those which are
obtained by reacting one or more polyhydric alcohols, preferably
the hindered polyols (such as the neopentyl polyols e.g. neopentyl
glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol,
trimethylol propane, pentaerythritol and dipentaerythritol) with
alkanoic acids containing at least about 4 carbon atoms such as C5
to C30 acids (such as saturated straight chain fatty acids
including caprylic acid, capric acid, lauric acid, myristic acid,
palmitic acid, stearic acid, arachic acid, and behenic acid, or the
corresponding branched chain fatty acids or unsaturated fatty acids
such as oleic acid, or mixtures thereof).
[0136] Suitable synthetic ester components include esters of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more
monocarboxylic acids containing from about 5 to about 10 carbon
atoms. Such esters are widely available commercially, for example,
the Mobil P-41 and P-51 esters (ExxonMobil Chemical Company).
[0137] Other esters may included natural esters and their
derivatives, fully esterified or partially esterified, optionally
with free hydroxyl or carboxyl groups. Such ester may included
glycerides, natural and/or modified vegetable oils, derivatives of
fatty acids or fatty alcohols.
[0138] Silicon-based oils are another class of useful synthetic
lubricating oils. These oils include polyalkyl-, polyaryl-,
polyalkoxy-, and polyaryloxy-siloxane oils and silicate oils.
Examples of suitable silicon-based oils include tetraethyl
silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,
tetra-(4-methylhexyl)silicate, tetra-(p-tert-butylphenyl)silicate,
hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes, and
poly-(methyl-2-mehtylphenyl) siloxanes.
[0139] Another class of synthetic lubricating oil is esters of
phosphorus-containing acids. These include, for example, tricresyl
phosphate, trioctyl phosphate, diethyl ester of decanephosphonic
acid.
[0140] Another type of base stocks and base oils includes polymeric
tetrahydrofurans and the like, and their derivatives where reactive
pendant or end groups are partially or fully derivatized or capped
with suitable hydrocarbyl groups which may optionally contain O, N,
or S.
[0141] The highly beneficial viscosity advantages of the novel base
stocks and base oils described herein can be realized in
combination with one or more performance additives, and with the
desirable measured-to-theoretical viscosity ratios at less than -25
C, preferably at -30 C or lower, being realized in the resulting
formulated lubricant compositions or functional fluids. These
lubricant compositions or functional fluids also have the unique
and highly desirable characteristic of a measured-to-theoretical
viscosity ratio of 1.2 or lower, preferably 1.16 or lower, and in
many instances more preferably 1.12 or lower. Thus the effect of
the measured-to-theoretical viscosity feature of the novel base
stocks and base oils described herein is preserved even in the
presence of performance additives, leading to improved formulated
lubricant compositions or functional fluids comprising the novel
base stocks and base oils described herein and one or more
performance additives.
[0142] Performance Additives
[0143] The instant invention can be used with additional lubricant
components in effective amounts in lubricant compositions, such as
for example polar and/or non-polar lubricant base oils, and
performance additives such as for example, but not limited to,
metallic and ashless oxidation inhibitors, metallic and ashless
dispersants, metallic and ashless detergents, corrosion and rust
inhibitors, metal deactivators, anti-wear agents (metallic and
non-metallic, low-ash, phosphorus-containing and non-phosphorus,
sulfur-containing and non-sulfur types), extreme pressure additives
(metallic and non-metallic, phosphorus-containing and
non-phosphorus, sulfur-containing and non-sulfur types),
anti-seizure agents, pour point depressants, wax modifiers,
viscosity index improvers, viscosity modifiers, seal compatibility
agents, friction modifiers, lubricity agents, anti-staining agents,
chromophoric agents, defoamants, demulsifiers, and others. For a
review of many commonly used additives see Klamann in Lubricants
and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN
0-89573-177-0, which also gives a good discussion of a number of
the lubricant additives discussed mentioned below. Reference is
also made "Lubricant Additives" by M. W. Ranney, published by Noyes
Data Corporation of Parkridge, N.J. (1973). In particular, the base
oils of this invention can show significant performance advantages
with modern additives and/or additive systems, and additive
packages that impart characteristics of low sulfur, low phosphorus,
and/or low ash to formulated lubricant compositions or functional
fluids.
[0144] Anitwear and Extreme Pressure Additives
[0145] Additional antiwear additives may be used with the present
invention. While there are many different types of antiwear
additives, for several decades the principal antiwear additive for
internal combustion engine crankcase oils is a metal
alkylthiophosphate and more particularly a metal
dialkyldithiophosphate in which the primary metal constituent is
zinc, or zinc dialkyldithiophosphate (ZDDP). ZDDP compounds
generally are of the formula Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.- 2
where R.sup.1 and R.sup.2 are C.sub.1-C.sub.18 alkyl groups,
preferably C.sub.2-C.sub.12 alkyl groups. These alkyl groups may be
straight chain or branched. For example, suitable alkyl groups
include isopropyl, 4-methyl-2-pentyl, and isooctyl. The ZDDP is
typically used in amounts of from about 0.4 wt % to about 1.4 wt. %
of the total lube oil composition, although more or less can often
be used advantageously.
[0146] However, it is found that the phosphorus from these
additives has a deleterious effect on the catalyst in catalytic
converters and also on oxygen sensors in automobiles. One way to
minimize this effect is to replace some or all of the ZDDP with
phosphorus-free antiwear additives.
[0147] A variety of non-phosphorus additives are also used as
antiwear additives. Sulfurized olefins are useful as antiwear and
EP additives. Sulfur-containing olefins can be prepared by
sulfurization or various organic materials including aliphatic,
arylaliphatic or alicyclic olefinic hydrocarbons containing from
about 3 to 30 carbon atoms, preferably 3-20 carbon atoms. The
olefinic compounds contain at least one non-aromatic double bond.
Such compounds are defined by the formula
R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6 where each of R.sup.3-R.sup.6
are independently hydrogen or a hydrocarbon radical. Preferred
hydrocarbon radicals are alkyl or alkenyl radicals. Any two of
R.sup.3-R.sup.6 may be connected so as to form a cyclic ring.
Additional information concerning sulfurized olefins and their
preparation can be found in U.S. Pat. No. 4,941,984, incorporated
by reference herein in its entirety.
[0148] The use of polysulfides of thiophosphorus acids and
thiophosphorus acid esters as lubricant additives is disclosed in
U.S. Pat. Nos. 2,443,264; 2,471,115; 2,526,497; and 2,591,577.
Addition of phosphorothionyl disulfides as an antiwear,
antioxidant, and EP additives is disclosed in U.S. Pat. No.
3,770,854. Use of alkylthiocarbamoyl compounds
(bis(dibutyl)thiocarbamoyl, for example) in combination with a
molybdenum compound (oxymolybdenum diisopropylphosphorodithioate
sulfide, for example) and a phosphorus ester (dibutyl hydrogen
phosphite, for example) as antiwear additives in lubricants is
disclosed in U.S. Pat. No. 4,501,678. U.S. Pat. No. 4,758,362
discloses use of a carbamate additive to provide improved antiwear
and extreme pressure properties. The use of thiocarbamate as an
antiwear additive is disclosed in U.S. Pat. No. 5,693,598.
Thiocarbamate/molybdenum complexes such as moly-sulfur alkyl
dithiocarbamate trimer complex (R.dbd.C.sub.8-C.sub.18 alkyl) are
also useful antiwear agents. Each of the above mentioned patents is
incorporated by reference herein in its entirety.
[0149] Esters of glycerol may be used as antiwear agents. For
example, mono-, di, and tri-oleates, mono-palmitates and
mono-myristates may be used.
[0150] ZDDP is combined with other compositions that provide
antiwear properties. U.S. Pat. No. 5,034,141 discloses that a
combination of a thiodixanthogen compound (octylthiodixanthogen,
for example) and a metal thiophosphate (ZDDP, for example) can
improve antiwear properties. U.S. Pat. No. 5,034,142 discloses that
use of a metal alkyoxyalkylxanthate (nickel ethoxyethylxanthate,
for example) and a dixanthogen (diethoxyethyl dixanthogen, for
example) in combination with ZDDP improves antiwear properties.
[0151] Antiwear additives may be used in an amount of about 0.01 to
6 weight percent, preferably about 0.01 to 4 weight percent.
[0152] Viscosity Index Improvers
[0153] 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 at elevated temperatures and acceptable viscosity
at low temperatures.
[0154] Suitable viscosity index improvers include both low
molecular weight and high molecular weight hydrocarbons, polyesters
and viscosity index improver dispersants that 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 500,00, and even more typically
between about 50,000 and 200,000.
[0155] Examples of suitable viscosity index improvers are polymers
and copolymers of methacrylate, butadiene, olefins, or alkylated
styrenes. Polyisobutylene is a commonly used viscosity index
improver. Another suitable viscosity index improver is
polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity index improvers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, and polyacrylates (copolymers
of various chain length acrylates, for example). Specific examples
include styrene-isoprene or styrene-butadiene based polymers of
about 50,000 to 200,000 molecular weight.
[0156] Viscosity index improvers may be used in an amount of about
0.01 to 15 weight percent, preferably about 0.01 to 10 weight
percent, and in some instances, more preferably about 0.01 to 5
weight percent.
[0157] Antioxidants
[0158] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricating oil compositions. See,
Klamann in Lubricants and Related Products, op cite, and U.S. Pat.
Nos. 4,798,684 and 5,084,197, for example, the disclosures of which
are incorporated by reference herein in their entirety. Useful
antioxidants include hindered phenols. These phenolic antioxidants
may be ashless (metal-free) phenolic compounds or neutral or basic
metal salts of certain phenolic compounds. Typical phenolic
antioxidant compounds are the hindered phenolics which are the ones
which contain a sterically hindered hydroxyl group, and these
include those derivatives of dihydroxy aryl compounds in which the
hydroxyl groups are in the o- or p-position to each other. Typical
phenolic antioxidants include the hindered phenols substituted with
C.sub.6+ alkyl groups and the alkylene coupled derivatives of these
hindered phenols. Examples of phenolic materials of this type
2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol;
2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant invention. Examples of ortho coupled
phenols include: 2,2'-bis(6-t-butyl-4-heptyl phenol);
2,2'-bis(6-t-butyl-4-octyl phenol); and
2,2'-bis(6-t-butyl-4-dodecyl phenol). Para coupled bis phenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0159] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.10 is H, alkyl, aryl or R.sup.11(O).sub.xR.sup.12 where
R.sup.11 is an alkylene, alkenylene, or aralkylene group, R.sup.12
is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and
x is 0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to
about 20 carbon atoms, and preferably contains from 6 to 12 carbon
atoms. The aliphatic group is a saturated aliphatic group.
Preferably, both R.sup.8 and R.sup.9 are aromatic or substituted
aromatic groups, and the aromatic group may be a fused ring
aromatic group such as naphthyl. Aromatic groups R.sup.8 and
R.sup.9 may be joined together with other groups such as S.
[0160] Typical aromatic amines antioxidants have alkyl substituent
groups of at least about 6 carbon atoms. Examples of aliphatic
groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally,
the aliphatic groups will not contain more than about 14 carbon
atoms. The general types of amine antioxidants useful in the
present compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines.
Mixtures of two or more aromatic amines are also useful. Polymeric
amine antioxidants can also be used. Particular examples of
aromatic amine antioxidants useful in the present invention
include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0161] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants. Low sulfur peroxide
decomposers are useful as antioxidants.
[0162] Another class of antioxidant used in lubricating oil
compositions is oil-soluble copper compounds. Any oil-soluble
suitable copper compound may be blended into the lubricating oil.
Examples of suitable copper antioxidants include copper
dihydrocarbyl thio or dithio-phosphates and copper salts of
carboxylic acid (naturally occurring or synthetic). Other suitable
copper salts include copper dithiacarbamates, sulphonates,
phenates, and acetylacetonates. Basic, neutral, or acidic copper
Cu(I) and or Cu(II) salts derived from alkenyl succinic acids or
anhydrides are know to be particularly useful.
[0163] Preferred antioxidants include hindered phenols, arylamines,
low sulfur peroxide decomposers and other related components. These
antioxidants may be used individually by type or in combination
with one another. Such additives may be used in an amount of about
0.01 to 5 weight percent, preferably about 0.01 to 2 weight
percent.
[0164] Friction Modifiers
[0165] A friction modifier is any material or materials that can
alter the coefficient of friction of any lubricant or fluid
containing such material(s). Friction modifiers, also known as
friction reducers, or lubricity agents or oiliness agents, and
other such agents that change the coefficient of friction of
lubricant base oils, formulated lubricant compositions, or
functional fluids, may be effectively used in combination with the
base oils or lubricant compositions of the present invention if
desired. Friction modifiers that lower the coefficient of friction
are particularly advantageous in combination with the base oils and
lube compositions of this invention. Friction modifiers may include
metal-containing compounds or materials as well as ashless
compounds or materials, or mixtures thereof. Metal-containing
friction modifiers may include metal salts or metal-ligand
complexes where the metals may include alkali, alkaline earth, or
transition group metals. Such metal-containing friction modifiers
may also have low-ash characteristics. Transition metals may
include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include
hydrocarbyl derivative of alcohols, polyols, glycerols, partial
ester glycerols, thiols, carboxylates, carbamates, thiocarbamates,
dithiocarbamates, phosphates, thiophosphates, dithiophosphates,
amides, imides, amines, thiazoles, thiadiazoles, dithiazoles,
diazoles, triazoles, and other polar molecular functional groups
containing effective amounts of O, N, S, or P, individually or in
combination. In particular, Mo-containing compounds can be
particularly effective such as for example Mo-dithiocarbamates,
Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am),
Mo-alcoholates, Mo-alcohol-amides, etc.
[0166] Ashless friction modifiers may have also include lubricant
materials that contain effective amounts of polar groups, for
example hydroxyl-containing hydrocaryl base oils, glycerides,
partial glycerides, glyceride derivatives, and the like. Polar
groups in friction modifiers may include hyrdocarbyl groups
containing effective amounts of O, N, S, or P, individually or in
combination. Other friction modifiers that may be particularly
effective include, for example, salts (both ash-containing and
ashless derivatives) of fatty acids, fatty alcohols, fatty amides,
fatty esters, hydroxyl-containing carboxylates, and comparable
synthetic long-chain hydrocarbyl acids, alcohols, amides, esters,
hydroxy carboxylates, and the like. In some instances fatty organic
acids, fatty amines, and sulfurized fatty acids may be used as
suitable friction modifiers.
[0167] Useful concentrations of friction modifiers may range from
about 0.01 wt % to 10-15 wt % or more, often with a preferred range
of about 0.1 wt % to 5 wt %. Concentrations of molybdenum
containing materials are often described in terms of Mo metal
concentration. Advantageous concentrations of Mo may range from
about 10 ppm to 3000 ppm or more, and often with a preferred range
of about 20-2000 ppm, and in some instances a more preferred range
of about 30-1000 ppm. Friction modifiers of all types may be used
alone or in mixtures with the materials of this invention. Often
mixtures of two or more friction modifiers, or mixtures of friction
modifiers(s) with alternate surface active material(s), are also
desirable.
[0168] Pour Point Depressants
[0169] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
invention if desired. These pour point depressant may be added to
lubricating compositions of the present invention to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
polymethacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2,721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Each of these
references is incorporated herein in its entirety. Such additives
may be used in an amount of about 0.01 to 5 weight percent,
preferably about 0.01 to 1.5 weight percent.
[0170] Corrosion Inhibitors
[0171] Corrosion inhibitors are used to reduce the degradation of
metallic parts that are in contact with the lubricating oil
composition. Suitable corrosion inhibitors include thiadizoles.
See, for example, U.S. Pat. Nos. 2,719,125; 2,719,126; and
3,087,932, which are incorporated herein by reference in their
entirety. Such additives may be used in an amount of about 0.01 to
5 weight percent, preferably about 0.01 to 1.5 weight percent.
[0172] Seal Compatibility Additives
[0173] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Additives of this type are commercially
available. Such additives may be used in an amount of about 0.01 to
3 weight percent, preferably about 0.01 to 2 weight percent.
[0174] Anti-Foam Agents
[0175] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Anti-foam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 percent and
often less than 0.1 percent.
[0176] Inhibitors and Antirust Additives
[0177] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available; they are referred to also in Klamann, op.
cit.
[0178] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent. Additional types of additives may
be further incorporated into lubricant compositions or functional
fluids of this invention, and may include one or more additives
such as, for example, demulsifiers, solubilizers, fluidity agents,
coloring agents, chromophoric agents, and the like, as required.
Further, each additive type may include individual additives or
mixtures of additive.
[0179] Typical Additive Amounts
[0180] When lubricant compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
invention are shown in the Table 2 below.
[0181] Note that many additives, additive concentrates, and
additive packages that are purchased from manufacturers may
incorporate a certain amount of base oil solvent, or diluent, in
the formulation. Accordingly, the weight amounts in Table 3 below
are directed to the amount of active ingredient (that is the
non-solvent portion of the ingredient). The weight percents
indicated below are based on the total weight of the lubricating
oil composition. In practical applications, however, additive
components, additive concentrates, and additive packages are used
as purchased from manufactures, and may include certain amounts of
base oil solvent or diluent. The additive and formulation
components as recited in the Examples and Comparative Examples
below are used "as is" from their manufacturers or suppliers,
unless specifically noted otherwise.
2TABLE 2 Typical Amounts of Various Lubricant Oil Components
Approximate Weight Percent Approximate Weight Compound (Useful)
Percent (Preferred) Viscosity Index Improver 0-40 0.01-30, more
preferably 0.01 to 15 Antioxidant 0.01-5 0.01-2 Corrosion Inhibitor
0.01-5 0.01-1.5 Anti-wear Additive 0.01-6 0.01-4 Pour Point
Depressant 0-5 0.01-1.5 Demulsifier 0.001-3 0.001-1.5 Anti-foam
Agent 0.001-3 0.001-0.15 Base Oil(s) Balance Balance
EXAMPLES
Example 1
[0182] By controlling other non-inventive process parameters well
known to those skilled in the art, the inventive base stocks and
base oils as described by the inventive process herein can be made
over a range of low to high viscosity oils as is typical in the
industry thus allowing for blending of base stocks with a final
viscosity between those two end points. In this example, the base
stocks were manufactured using the inventive method to a higher
viscosity level of 6.6 cSt and a lower viscosity level of 4.0 cSt.
For this example, as may be seen in table 4, the Inventive Oil A
was derived from a mineral oil wax feedstock to the process
described herein and then blended to two viscometric targets: 4.0
cSt and 5.7 cSt. Similarly, the Inventive Oil B for this example
was derived from a Fischer-Tropsch wax, blended to final viscosity
targets of 4.0 cSt and 6.3 cSt. The Comparitive Oils for this
example are commercially available base stocks blended to
viscometric targets of 4 cSt, 5 cSt and 8 cSt.
[0183] Viscometric properties of Inventive base oils A and B and
the Comparative Base Oil 1 at comparable viscosity indices are
shown below (Table 3). The Kinematic Viscosities were measured by
ASTM method D445. The measured CCS viscosity were found by using
ASTM method D5293. The Theoretical Viscosity were calculated per
the Walther/MacCoull Equation as found in ASTM D341 (Appendix
1).
[0184] The ratio between measured and theoretical viscosity (i.e.
ratio=measured/theoretical) at -30 C or below is less than 1.2 for
the Inventive Base Oils, but is higher than 1.2 for the Comparative
Base Oils at the same temperatures.
3TABLE 3 Base Stocks and Properties Inventive Base Oil Comparative
Base Oil Oil A Oil A Oil B Oil B Comp. Oil 1 Comp. Oil 1 Comp. Oil
1 4 cSt 5.7 cSt 4 cSt 6.3 cSt 4 cSt 5 cSt 8 cSt Viscosity 142 150
143 153 142 146 146 Index Kinematic Viscosity, ASTM D445 at 100 C.,
cSt 4 5.7 3.8 6.30 4.0 5.1 8.0 at 40 C., cSt 16.8 28.4 15.3 31.8
16.5 24.1 46.3 CCS Viscosity (Measured), ASTM D5293 at -30 C., cP
TLTM 2506 680 2630 1160 2270 8000 at -35 C., cP 1354 4499 1140 4670
2440 4620 THTM Theoretical Viscosity (Walther/MacCoull Eq.) at -30
C., cP 894 2439 722 2806 866 1877 6056 at -35 C., cP 1515 4364 1206
5019 1466 3329 11 340 Viscosity Ratio, measured/theoretical at -30
C., cP -- 1.03 0.94 0.94 1.34 1.21 1.32 at -35 C., cP 0.89 1.03
0.94 0.93 1.66 1.39 -- (TLTM = too low to measure) (THTM = too high
to measure)
[0185] It has similarly being observed that the novel base stocks
recited herein have a much lower scanning-Brookfield viscosity
(ASTM D5133) values at low temperature (below -20 C). Scanning
Brookfield viscosity measurements are performed at much lower shear
rates, and slower cooling rates than the D5293 CCS technique. In
the particular example illustrate in table 4, the inventive base
stocks ratios of (measured/theoretically predicted) viscosity
ranges between 2.5 (@-20 C) and 7 (@-35 C), while the comparable
commercially available base stock, with similar viscosity and VI,
has a ratio ranging between 11 (@-20 C), and 63 (@-25 C), and its
viscosity is too high to be measured below -25 C.
[0186] The viscosity-temperature performance for the Comparative
Base Oil and the Inventive Base Oil are also demonstrably different
over a range of base oil viscosity, as measured by kinematic
viscosity at 100 C. At comparable kinematic viscosity at 100 C, it
is evident that the Inventive Base Oil has superior (i.e. lower)
low-temperature viscosity than that of comparative base oil 1, at
temperatures such as, for example, -30 C and -35 C (Table 4 and
FIG. 2).
4TABLE 4 Base Oil CCS Low-Temperature Viscosity at Comparable
Kinematic Viscosity Inventive Base Oil A Comparative Base Oil 1
4-6.6 cSt Mixtures 4-8 cSt Mixtures KV @ CCS @ CCS @ 100 C., -30 C.
CCS @ -35 C. -30 C. CCS @ -35 C. cSt cP cP cP cP 4.0 857 1445 1524
2798 4.6 1282 2214 2032 3713 6.0 2830 5120 3600 6700
Example 2
[0187] In this example (Table 5), the inventive functional fluid is
that of a hydraulic oil. The performance additive package A is
suitable for use in hydraulic oil compositions. However, these
examples do not limit the possible alternate lubricant compositions
that may be suitably used in this invention. These examples are
formulated to meet the same viscosity target of ISO 32 (viscosity
grade according to ISO 3448, as published by the International
Standards Organization), which is one of many typical viscosity
grades of hydraulic oils.
[0188] Surprisingly, Inventive Example 1, formulated exclusively
with the inventive base oil A of Example 1 and with no viscosity
modifier, demonstrates excellent Brookfield viscosity at -20 F of
3010 cP. This performance is significantly better (i.e. lower) than
that of comparative example CE.3 (a commercially available
composition, with mixed paraffinic/naphthenic-type mineral oils and
viscosity modifier) and is dramatically better (i.e lower) than
that of comparative example CE. 1 (formulated with only Group III
comparative base oil Comp.Oil 1 and no viscosity modifier).
[0189] Similarly, Inventive Example 2, formulated with the
inventive base oil A Example 1 and viscosity modifier, demonstrates
excellent Brookfield viscosity at -20 F of 2150 cP. This
performance is significantly better (i.e. lower) than that of the
other viscosity modified comparative examples CE. 1 (formulated
with Group III comparative base oil Comp.Oil 1 and viscosity
modifier) and CE.3 (a commercially available composition, with
mixed paraffinic/naphthenic-type mineral oils and viscosity
modifier).
5TABLE 5 Inventive and Comparative Examples Inventive Examples
Comparative Examples 1 2 CE.1 CE.2 CE.3 Formulated Lubricant
Composition (wt %) Inventive Base Oil A, 4 cSt 12.64 45.625
Inventive Base Oil A, 6 cSt 84.61 45.625 Comparative Base Oil 1, 5
cSt 56.41 91.25 Comparative Base Oil 1, 8 cSt 40.84 Mineral Oil,
150 SPN 55.5 Mineral Oil, 600 SPN 6.43 Mineral Oil, 65 SNN 29.32
Pour Point depressant 0.1 0.1 0.1 0.1 0.1 Viscosity Modifier 6 6 6
(Polymethacrylate) Hydraulic Additive Package A 2.65 2.65 2.65 2.65
2.65 Properties Kinematic Viscosity at 40 C., 32.7 32.4 32.8 32.4
32 cSt (D445) Kinematic Viscosity at 100 C., 6.4 7.1 6.3 7.0 6.1
cSt (D445) Viscosity Index (D2270) 149 190 148 186 142 Pour Point,
C (D97) -39 -51 -30 -42 -40 Brookfield Viscosity at -20 F., 3010
2150 137800 3960 4940 cP (D2983) (SPN = Solvent Paraffinic Neutral)
(SNN = Solvent Naphthenic Neutral)
[0190] These examples demonstrate a surprising and unexpected
advantage of the novel base stocks recited herein versus other
Group III base stocks in an application where low-temperature
viscosity is an essential contributor to overall good
wide-temperature performance.
* * * * *
References