U.S. patent application number 13/033920 was filed with the patent office on 2011-06-16 for additive system for lubricating fluids.
This patent application is currently assigned to THE LUBRIZOL CORPORATION. Invention is credited to Ellen B. Brandes, Halou Oumar-Mahamat, William T. Sullivan, Shi-Ming Wu.
Application Number | 20110143982 13/033920 |
Document ID | / |
Family ID | 36722491 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110143982 |
Kind Code |
A1 |
Sullivan; William T. ; et
al. |
June 16, 2011 |
Additive System for Lubricating Fluids
Abstract
The invention concerns an additive package for a lubricating
fluid or grease containing an effective amount of a
phosphorus-containing antiwear additive, the improvement comprising
the absence of primary, secondary, tertiary, cyclic low molecular
weight aliphatic amines with a carbon number of C30 or less.
Inventors: |
Sullivan; William T.;
(Brick, NJ) ; Oumar-Mahamat; Halou; (Princeton,
NJ) ; Wu; Shi-Ming; (Dayton, NJ) ; Brandes;
Ellen B.; (Round Brook, NJ) |
Assignee: |
THE LUBRIZOL CORPORATION
Wickliffe
OH
|
Family ID: |
36722491 |
Appl. No.: |
13/033920 |
Filed: |
February 24, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11333581 |
Jan 17, 2006 |
|
|
|
13033920 |
|
|
|
|
Current U.S.
Class: |
508/433 |
Current CPC
Class: |
C10N 2040/04 20130101;
C10N 2030/12 20130101; C10N 2030/52 20200501; C10N 2030/06
20130101; C10M 141/10 20130101; C10M 2223/04 20130101; C10N 2030/40
20200501; C10N 2030/04 20130101 |
Class at
Publication: |
508/433 |
International
Class: |
C10M 137/02 20060101
C10M137/02 |
Claims
1.-21. (canceled)
22. A method of lubricating an automotive or industrial gear or
differential comprising supplying to said gear or differential an
additive package for a fully formulated lubricating fluid and
including in said additive package an effective amount of an acid
phosphate-containing antiwear additive, wherein the additive
package is substantially free of primary, secondary, tertiary, and
cyclic aliphatic amines with a carbon number of C30 or less and of
the corresponding acid phosphate amine salts.
23. The method of claim 22, wherein said acid phosphate is selected
from at least one mono and/or dihydrocarbyl ester of an acid
phosphate characterized by the formula (I):
(R.sub.1O)(R.sub.2O)P(O)OH (1) where R.sub.1 is a hydrocarbyl group
and R.sub.2 is selected from hydrogen or a hydrocarbyl group.
24. The method of claim 22, wherein said additive package has a
TBN<22.
25. The method of claim 22, wherein said additive package has a
TBN<20.
26. The method of claim 22, wherein said additive package has a
TBN<15.
27. The method of claim 22, wherein said additive package has a
TBN<10.
28. The method of claim 22, wherein said additive package has a
TBN<5.
29. The method of claim 22, wherein the hydrocarbyl groups of
R.sub.1 and R.sub.2 are independently selected from
straight-chained or branched alkyl groups having from 1 to 20
carbon atoms.
30. The method of claim 22, wherein the hydrocarbyl groups of
R.sub.1 and R.sub.2 are independently selected from
straight-chained or branched alkyl groups having from 2 to 20
carbon atoms.
31. The method of claim 22, wherein the hydrocarbyl groups of
R.sub.1 and R.sub.2 are independently selected from
straight-chained or branched alkyl groups having from 3 to 20
carbon atoms.
32. The method of claim 22, wherein at least one of R.sub.1 and
R.sub.2 is 2-ethylhexyl.
33. The method of claim 22, wherein said additive package further
comprises at least one of the following ingredients: a. at least
one sulfur-containing extreme pressure agent; b. at least one
nitrogen-containing dispersant; c. at least one corrosion
inhibitor.
34. The method of claim 33, wherein said additive package comprises
at least two of the ingredients (a)-(c).
35. The method of claim 33, wherein said additive package comprises
ingredients (a)-(c).
36. The method of claim 33, wherein said additive package further
comprises at least one ingredient selected from the group
consisting of borated dispersants, non-aminic rust inhibitors,
defoamants, pour point depressants, antioxidants, demulsifiers,
friction modifiers, seal swell agents, chromophores, deodorants,
limited slip additives, detergents, VI modifiers, and
tackifiers.
37. The method of claim 22, wherein the gear is incorporated in a
device selected from the group consisting of planetary hub
reduction axles, mechanical steering and transfer gear boxes in
utility vehicles, synchromesh gear boxes, power take-off gears,
limited slip axles, and planetary hub reduction gear boxes.
Description
FIELD OF THE INVENTION
[0001] The invention relates to an additive system having
essentially no hydrocarbyl amine rust inhibitor of C30 or less,
suitable for use in lubricating fluids, and a fully formulated
lubricating fluid containing said additive system.
BACKGROUND OF THE INVENTION
[0002] Oxidative stability, seal compatibility, protection from
wear, and overall durability are highly sought after features of
gears oils for both automotive and industrial applications.
Original equipment manufacturers (OEMs) as well as the consuming
public are constantly demanding improvements such as extended drain
intervals from suppliers of gear oils.
[0003] Enhanced oxidative stability is highly desired in driveline
fluids (e.g., automotive transmissions and differentials) as well
as in gear boxes used for various industrial applications. When
oxidation is problematic, sludge and carbon/varnish deposits appear
on the gear surfaces, which may adversely impact the functioning of
the gears. Lubricants are expected to be able to pass lengthy
oxidation tests, e.g. the extended L-60-1 test (comprising a 200 hr
test for axle oils and 300 hr test for transmission oils). The
lubricant should be able to provide adequate cleanliness as well as
viscosity control to pass these tests.
[0004] In order to prepare lubricants which are oxidatively stable,
it has become common practice to add antioxidants to the
lubricating oil, either phenolic or arylamine types. Alternatively,
formulators can choose to use certain base stocks and/or additive
combinations which are less prone to oxidation.
[0005] Gear oils that are expected to survive for long drain
intervals should also be able to leave seals undamaged so that no
leakage occurs during the lifetime of the gear box. Axle and
transmission seal materials in the U.S. and Europe include
fluoroelastomer, nitrile and polyacrylate. Static and dynamic seal
testing in the U.S. and Europe are part of industry and OEM
performance specifications for both industrial and automotive gear
oil.
[0006] One of the most important features of a gear oil is its
ability to prevent gear distress, which if severe enough, can
ultimately lead to catastrophic failure of the gears. Gear distress
or wear can be in the form of pitting, spalling, ridging, rippling,
etc. for automotive gears, especially those in the differential
because of the loads. To control wear, it is common to add
anti-wear additives to reduce or prevent damage. These additives
preferably should be able to function at temperatures from sub-zero
to temperatures around 160.degree. C., which could be reached if
the vehicle is subjected to severe operating conditions. In
addition, to perform most effectively, anti-wear additives
preferably should be able to function in the presence of other
aggressive additives that perform key functions, e.g. extreme
pressure additives, and they preferably should be able to continue
to function for long operating periods.
[0007] There are industry tests for examining the effectiveness of
antiwear additive systems. In the automotive industry, the L-37 is
most widely recognized. This rig test simulates low speed, high
torque operation. A low temperature modification of this test is
also part of the API GL-5 and SAE J2360 specification for 75W
graded gear lubricants. The low temperature version of this test is
known as the Canadian version. There also exists a high temperature
version of the L-37 test, which is included in several OEM
specifications. In the L-37 test, and its variants, the gears are
disassembled at the end of the test and the gear distress is
rated.
[0008] Commonly used anti-wear additives are phosphorous containing
compounds. They usually include amine-neutralized salts of
phosphorus acids, phosphinyl acids, phosphonyl acids,
thiophosphorus acids, thiophosphinyl acids, thiophosphonyl acids,
and the partial esters of these. The amines useful in preparing the
amine salts are primary or secondary hydrocarbyl monoamines or
polyamines containing about 4-30 carbon atoms. They may also be
tertiary or cyclic amines. The most common amines are primary,
fatty amines containing 10-20 carbon atoms, like octadecyl amine or
tertiary alkyl amines like C12-C14 tertiary alkyl primary amine,
commercially available as "Primene 81-R." It is commonly believed
that the amine neutralization is a necessary feature of the
different phosphorus-containing compounds, because of its ability
to impart critically required steel corrosion protection and
thermal stability.
[0009] In order to reach the extended drain intervals that OEMs are
now seeking for their gear boxes and differentials, durability is
important for gear oils, both automotive and industrial. The
durability of a fluid will depend on the base oils that are being
used, e.g. synthetic base oils will be far more durable than API
Group I and II fluids because of the superior oxidative and thermal
stability. However, base oil selection is only part of the picture
for formulating gear oils with improved durability. The additive
system must also be carefully chosen so as to provide oxidation
stability, seal compatibility and antiwear performance, all of
which contribute to an oil's durability.
[0010] Industrial and automotive gear lubes perform in much the
same way, though loads on the industrial gears tend to be spread
out over larger surface areas and therefore are not as great as
those seen in the rear axle of an automotive vehicle. Nevertheless,
similar features would be considered desirable in both types of
gear oils. Durability, for example, is important as this would
equate to longer drain intervals and reduced down time and reduced
maintenance costs. Durability in the form of improved oxidative
stability, reduced wear and better seal compatibility are highly
desired for all types of gear oils.
[0011] Because there are numerous additives added to such
compositions for many diverse reasons and with each additive
interacting with all the other additives in some manner, it is
extremely difficult to find new formulations showing an improvement
in at least one property while having little or no detrimental
effects on other properties. Nevertheless, the prior art is filled
with many attempts to prepare gear additive concentrates and gear
lubricant compositions with improvements in the areas of extreme
pressure/antiwear, thermal stability, oxidative stability and the
like.
[0012] U.S. Pat. No. 6,844,300 and EP 1 233 051 A1 teach that a
gear oil comprising a base oil, a thermally stable P-containing
antiwear additive and a metal free sulfur EP agent, wherein the S
is present at least at a level of 10,000 ppms, and the P is present
from 100-350 ppms will meet GL-5 requirements. The thermally stable
antiwear additive is defined as oil soluble amine salts of
phosphoric acid esters as well as reaction products of
dicyclopentadiene and thiophosphoric acid. The salts may be formed
beforehand or in situ.
[0013] U.S. Pat. No. 6,046,144 describes synergistic antioxidant
compositions comprising amine salts of alkyl phosphates, and
ethylenediamine, ammonium or metal salts of
alkylarylsulfonates.
[0014] U.S. Pat. No. 5,942,470 teaches the use of combining at
least one oil soluble sulfur-containing extreme pressure or
antiwear agent with at least one oil soluble amine salt of a
partial ester of an acid of phosphorus and with at least one oil
soluble succinimide dispersant of a formula defined in the patent.
A lengthy list of many suitable amine salts of the partially
esterified phosphorus is included in the patent. Primary amines are
preferred.
[0015] U.S. Pat. No. 5,763,372 discusses "clean gear" boron-free
gear additive systems, which employ an ashless boron-free
dispersant, a sulfur source, and a phosphorus source, wherein at
least one is chosen from a group of oil-soluble amine salts of acid
phosphates.
[0016] U.S. Pat. No. 5,756,429 describes a composition suitable for
high speed gears having a peripheral speed of at least 10 msec
containing a base oil having a % Ca of 5 or less and a S, P, N
ratio of 100N/(S+P) between 4 and 10 by weight. Use of acid
phosphates and their amine salts are preferred. The composition is
said to be able to inhibit sludge and permit the prolongation of
the life of an oil seal.
[0017] U.S. Pat. No. 5,691,283 describes a transmission and axle or
differential gearing which comprises a base oil and a Mannich
dispersant, a sulfur-containing EP agent, a P- and N-containing
antiwear additive, and an overbased alkali or alkaline earth
carboxylate, sulphonate, or sulfurized phenate having a TBN (Total
Base Number) of at least 145.
[0018] U.S. Pat. No. 5,573,696 and U.S. Pat. No. 5,500,140 discuss
the preparation of amine-neutralized acid phosphates, which are
prepared by reacting P.sub.2O.sub.5 with an alcohol prepared from
the reaction of an epoxide with dihydrocarbyl phosphorothioic
acid.
[0019] U.S. Pat. No. 5,547,596 describes a lubricant composition
for the limited slip differential (LSD) of a car which is obtained
by adding a phosphate amine salt, such as an amine salt of an oleyl
acid phosphate and a borated ashless dispersant, such that the
ratio of N/P is 0.5-1.0; the ratio of N/B is 4-10; the phosphorus
content is in the range of 0.15-0.4% by weight; and the boron
content is in the range of 0.01 to 0.04% by weight. This lubricant
composition inhibits the generation of chattering during the
operation of a LSD device and has excellent oxidative
stability.
[0020] U.S. Pat. No. 5,358,650, U.S. Pat. No. 5,571,445, and WO
94/22990 describe a synthetic fluid which includes a variety of
synthetic base oils plus specified amounts of the following: a
sulfur-containing extreme pressure-antiwear agent, a P-containing
antiwear agent, a corrosion inhibitor, an amine and/or carboxylic
acid rust inhibitor, a foam inhibitor, and an ashless
dispersant.
[0021] U.S. Pat. No. 5,354,484 describes how improved high
temperature stability can be achieved with the presence of at least
one soluble tertiary aliphatic primary amine salt, wherein the
primary amine contains 4-30 carbon atoms, at least one of which is
a substituted phosphoric acid, in combination with a borated
succinimide dispersant.
[0022] U.S. Pat. No. 5,328,619 describes an additive concentrate
comprising at least one oil soluble organic acid, e.g. one or more
hydrocarbyl phosphoric acids, one or more carboxylic acids or a
combination of the two, and a hydrocarbyl amine which is added such
that the pH of the finished concentrate is in the 6.0-7.0 range. A
borated dispersant is introduced into the concentrate being formed
when the concentrate is at least 6.0. The resulting compositions
are said to inhibit haze in the resulting concentrates, and the pH
control can provide gear compositions having enhanced extreme
pressure performance in the L-42 test, and improved rust in the
L-33 test.
[0023] U.S. Pat. No. 4,575,431 discusses the combination of
dihydrocarbyl hydrogen thiophosphates and hydrocarbyl dihydrogen
phosphates and dihydrocarbyl hydrogen phosphates, with the
phosphates being at least 50% neutralized with a hydrocarbyl amine
that is C10-C30.
[0024] U.S. Pat. No. 4,431,552 discusses a lubricating composition
having dispersed therein a hydrated alkali metal borate extreme
pressure agent and an effective amount of a mixture of a phosphate,
a monothiophosphate, and a dithiophosphate. All of the phosphates
are preferably used as their hydrocarbyl amine salts.
[0025] U.S. Pat. No. 4,118,328 discusses the preparation and use of
phosphate salts comprised of heating a triaryl phosphate and a
primary or secondary aliphatic amine in a 1-20 molar ratio,
respectively, with a trace amount of boric acid for catalyst.
[0026] U.S. Pat. No. 3,728,260 describes the preparation of a
neutral hydrocarbyl phosphate in combination with an alkyl amine
hydrocarbyl phosphate salt for improved load carrying.
[0027] EP 531 585 describes the use of an additive composition
which includes a borated Mannich dispersant, a sulfur containing
anti-wear or EP agent, a metal free phosphorus-containing
antiwear-EP agent, and an oil-soluble amine salt of a carboxylic
acid. Free amine may or may not be present, and may or may not be
complexed to the phosphorus antiwear agent.
[0028] EP 519 760 B1 teaches that an oil soluble amine is used to
adjust the pH of an additive concentrate to 6-7 then dispersant is
added after this adjustment is made.
[0029] EP 391 653 B1 and EP 450 208 B1 both discuss having high
concentrations of amines along with suitable quantities of weak
acids, e.g. carboxylic acids, in the presence of sulfurized
isobutylene and P-containing antiwear additives to provide gear
oils with improved gear performance based on the results of a
Planetary Spur Gear Test.
[0030] UK 2,108,147 examines the use of oil soluble overbased
sodium salts of phosphate esters in lubricant compositions.
[0031] WO 03/1004620 A2 discusses a lubricating composition with
improved efficiency for an emissions control system, wherein the
compositions contain a metal-containing detergent, a metal salt of
one or more phosphorus acids or the corresponding esters, and an
acylated nitrogen-containing compound having at least 10 carbon
atoms. The resulting TBN composition has a phosphorus concentration
of up to about 0.12%.
[0032] U.S. Pat. No. 4,900,460 covers sulfurized olefins reacted
with phosphates and phosphites. The reaction product is useful as
an extreme pressure and wear additive for lube compositions.
[0033] U.S. Pat. No. 3,513,093 describes a composition containing a
major part of a lubricating oil and minor portion of a substituted
polyamine, which is prepared by reacting a polyamine with a
succinic acid producing hydrocarbon having at least 50 carbons with
at least 0.001 moles of a phosphorus acid producing compound
selected from the class of phosphoric acids, phosphorus acids,
phosphonyl acids, phosphinyl acids, etc. These species were found
to give improved oxidation performance in a variety of bench and
engine tests.
[0034] U.S. Pat. No. 2,224,695 teaches the preparation of a
corrosion inhibitor for metals which comprises an ester of an acid
of phosphorus having at least one of the hydrogen atoms of the acid
replaced by an ester group and at least one of the hydrogen atoms
replaced by an inorganic radical, upon exposing it to a metal
surface. Under favorable conditions, it reacts chemically with
metal surfaces to form a protective coating and inhibit corrosive
wear.
[0035] EP 531 000 B1 discusses an additive composition containing
a.) a reaction product of a phosphorus or thiophosphorus acid with
an ashless dispersant and a boron compound and b.) a sulfur
containing antiwear-EP agent. The gear oil prepared with these
components is said to have these performance improvements: 1.)
inhibition of scoring/scuffing, 2.) improved wear in the form of
ridging, rippling, pitting and spalling, 3.) improved oxidation in
the form of reduced sludge and varnish deposits, especially at
higher temperatures.
[0036] The present inventors have surprisingly discovered an
additive package, suitable for preparing a lubricant or grease
composition, that does not make use of primary, secondary,
tertiary, or cyclic aliphatic low molecular weight (<C30) amines
and therefore, it does not contain the corresponding acid phosphate
amine salts, and yet, it provides for lubricants exhibiting, in
preferred embodiments, improved performance in at least one of the
areas of oxidative stability, seal compatibility, and anti-wear
protection, while causing no significant deficits in other
important areas of performance.
SUMMARY OF THE INVENTION
[0037] The invention is directed to an additive package for
lubricating fluids or greases, the improvement characterized by the
absence of primary, secondary, tertiary and cyclic hydrocarbyl
amines with a carbon number of C30 or less and the absence of the
corresponding acid phosphate amine salts.
[0038] In an embodiment, the additive system is further
characterized by possessing a total base number (TBN) of less than
22.
[0039] In an embodiment, the invention is further characterized as
comprising an effective amount of an acid phosphate antiwear
additive. In preferred embodiments, the phosphate antiwear additive
will be at least one mono- and/or dialkyl acid phosphate effective
for antiwear protection.
[0040] Preferred mono- and/or dialkyl acid phosphates are
represented by the formula (R.sub.1O)(R.sub.2O)P(O)OH, where
R.sub.1 is hydrocarbyl and R.sub.2 is hydrocarbyl or hydrogen.
R.sub.1 and R.sub.2 may have the same or different hydrocarbyl
groups.
[0041] It is an object of the invention to provide an additive
package suitable for preparing fully formulated lubricating fluids
and greases and preferably having improvements in at least one of
the properties of antiwear protection, oxidative stability, and
seal performance.
[0042] These and other objects, features, and advantages will
become apparent as reference is made to the following detailed
description, preferred embodiments, examples, and appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] In the accompanying drawings, like reference numerals are
used to denote like parts throughout the several views.
[0044] FIG. 1 is a comparison of TBN for formulations according to
embodiments of the invention versus a commercial additive
package.
[0045] FIG. 2 is a comparison of the carbon varnish rating of
formulations according to embodiments of the present invention
versus formulations outside of the present invention.
DETAILED DESCRIPTION
[0046] According to embodiments of the invention, an additive
package is provided without, or essentially free of, the use of
primary, secondary, tertiary, and cyclic hydrocarbyl amine rust
inhibitors with carbon numbers of C30 or less, and/or the
corresponding acid phosphate amine salts which, in certain
embodiments, provides improvements in at least one of the areas of
oxidation stability, seal compatibility and anti-wear performance,
while causing no appreciable deficits in other areas of
performance. Such lubricant and grease compositions are
particularly useful in automotive gear boxes and differentials as
well as industrial gear boxes.
[0047] In preferred embodiments, the additive package of the
invention comprises an acid phosphate antiwear additive, preferably
one or more hydrocarbyl or dihydrocarbyl acid phosphates, said
additive package characterized as essentially free of acid
phosphate hydrocarbyl amine salts, where the hydrocarbyl amine is
C30 or less, present in said fully formulated compositions. Until
now, it has been believed that the stability of a
phosphate-containing antiwear additive was dependent on the
presence of this hydrocarbyl amine such that the phosphorus species
is present, wholly or at least in part, as a salt of the amine with
the acid phosphate. It is the surprising discovery of the present
inventors that such is not the case. Moreover, improvements in
certain important properties are evident in certain compositions
according to embodiments of the present invention.
[0048] It should be understood that in the expression "effective
amount of a acid phosphate antiwear additive", both the "effective
amount" and the identity of the acid phosphate-containing compound
effective as an antiwear additive can readily be determined by one
of ordinary skill in the art in possession of the present
disclosure without more than routine experimentation.
[0049] As used herein, the term "phosphate" does not include any of
the sulfur-containing compounds, e.g., thiophosphate compounds. In
an embodiment, the acid phosphate may be present as the mono and/or
dihydrocarbyl esters of the acid phosphate. The resulting gear
lubricant is essentially free of hydrocarbyl primary, secondary,
tertiary, and cyclic hydrocarbyl amines with less than or equal to
30 carbons as an ingredient (when the invention is expressed as a
"recipe" of ingredients) and therefore the final fully formulated
lubricant is essentially free of the corresponding acid phosphate
amine salts.
[0050] In order to avoid misunderstanding, "essentially free of"
allows minor amounts, such as inevitable impurities which might
lead to the presence of one or more of primary, secondary,
tertiary, cyclic aliphatic amines with thirty carbons or less (C30
or less) and/or the presence of the corresponding acid phosphate
amine salts, but these ingredients and the constituents that form
them are not present in amounts that effect the novel and basic
characteristics of the present invention.
[0051] By omitting these amines from the additive concentrate and
ultimately the lubricant, the additive system will have a
significantly reduced total base number (TBN) for the package. The
additive concentrates covered by embodiments of this invention have
a TBN<22, some cases less than 20, or less than 15, or less than
10, or even less than 5.
[0052] FIG. 1 is a plot of TBN and TAN (Total Acid Number) of a
commercial additive package versus additive packages which are
embodiments of the present invention. The commercial additive
package was chosen because it has the lowest TBN in the population
of commercial additive packages examined by the inventors. All
other commercial packages tested by the inventors had higher TBN
numbers. It is highly surprising that the additive packages
according to embodiments of the present invention can provide the
benefits set forth herein with low TBN in view of the TBN of tested
commercial products.
[0053] In addition, by omitting essentially all of the low
molecular (.ltoreq.C30) hydrocarbyl amine rust inhibitors from the
gear lubricant, and therefore eliminating the corresponding
phosphate amine salts, a number of very important performance
benefits may be achieved in embodiments, which in preferred
embodiments contribute enhanced durability.
[0054] The first of these performance benefits is enhanced antiwear
performance. As discussed in the experimental section below,
testing according to the industry-recognized L-37 rig test (ASTM
D6121) has shown significant improvements particularly in the low
temperature version (conventionally known as the "Canadian
version") of this test.
[0055] Also, in embodiments, the oxidative stability of gear oils
without the hydrocarbyl amine rust inhibitor described earlier is
superior to those with such an amine present. It has been shown by
embodiments that when these low molecular weight (<C30)
hydrocarbyl amines are eliminated from a gear lubricant, the
oxidation performance is dramatically improved. This can be
demonstrated using the industry oxidation test called the L-60-1
(ASTM D5704).
[0056] Improved seal performance was also noted from a gear
lubricant formulated in accordance with embodiments of the
invention. The ASTM D5562 static seal test was run using both
fluoroelastomer (Viton) and polyacrylate seal materials. In both
tests, the elongation percent loss was significantly reduced.
[0057] Prior to the present invention, it was expected that fluids
formulated without low molecular weight hydrocarbyl amine rust
inhibitors would be deficient in the area of rust inhibition. In
embodiments of the invention, the rust performance of gear
lubricants prepared within the scope of the invention was evaluated
using the automotive gear industry's L-33 test (ASTM D7038). The
results demonstrate that fluids formulated in this manner had no
steel corrosion deficiencies.
[0058] It is preferred that the additive package according to
embodiments of the present invention also include at least one of
the ingredients selected from the group consisting of: a
sulfur-containing extreme pressure (EP) agent, a
nitrogen-containing dispersant, and a corrosion inhibitor. Other
preferred additives may include at least one ingredient selected
from the group consisting of: borated dispersants, non-aminic rust
inhibitors, defoamants, pour point depressants, antioxidants,
demulsifiers, friction modifiers, seal swell agents, chromophores,
deodorants, limited slip additives, detergents, and tackifiers.
[0059] In an embodiment, the invention is directed to an additive
package comprising a minor amount of at least one substituted
phosphoric acid composition characterized by the formula
(R.sub.1O)(R.sub.2O)P(O)OH, where R.sub.1 is a hydrocarbyl group
and R.sub.2 is either hydrogen or a hydrocarbyl group.
[0060] The lubricant composition preferably will also contain a
sulfur-containing extreme pressure agent, as described more fully
below.
[0061] The lubricant composition preferably also will contain
nitrogen-containing dispersants and corrosion inhibitors, with the
proviso that said species will be essentially free of low molecular
weight primary, secondary, tertiary, cyclic aliphatic mono or
polyamines with a carbon number of C30 or less.
[0062] In some instances, the additive package of embodiments of
the invention will be mixed with, added to, dispersed in, or
otherwise formulated to make a useful product with an oil of
lubricating viscosity, such as a fluid categorized as being in one
of the well-known API Group I-V. Lubricating fluids and greases in
accordance with embodiments may comprise a major amount of such an
oil of lubricating viscosity and the additive package as set forth
herein. The term "major amount" means present in an amount greater
than any other ingredient, based on wt. %. The "oil of lubricating
viscosity" will also be described as a "base oil" herein, and may
be a combination of one or more base oils, with the term "major
amount" meaning the sum of the base oils are present in an amount
greater than any other ingredient.
[0063] The additive package according to embodiments of the
invention may comprise a small amount of an oil of lubricating
viscosity to serve as a diluent and the like, present in a minor
amount, such as 0-20 wt %, or about 0.5 to 15 wt %, or about 1 to
10 wt %, or about 2 to 8 wt %, or about 4 to 6 wt %, in the
additive package. Contemplated ranges include any of the
aforementioned lower limits to any of the aforementioned upper
limits, e.g., about 0 to 6 wt %. The term "diluent" as used herein
will imply a small amount, certainly less than a "major amount" for
the sum total of diluent.
[0064] The products in accordance with embodiments of the present
invention may be used, for instance, with an oil of lubricating
viscosity, for a wide variety of automotive and industrial gear
applications. Examples of such applications include use in hypoid
axles and in mechanical steering drives in passenger cars and in
cross-country vehicles. In addition, the product in accordance with
embodiments of the present invention may be used in planetary hub
reduction axles, mechanical steering and transfer gear boxes in
utility vehicles such as trucks. It also can be used in different
types of gear boxes, e.g. synchromesh gear boxes, as well as power
take-off gears, limited slip axles, and Planetary hub reduction
gear boxes. It may also be used in functional fluids, e.g., a
circulating or process oil, in metal working, and the like.
[0065] It will be recognized that in certain instances it may be
convenient to have a lubricant composition which is not completely
formulated solely with the additive package according to
embodiments of the invention, i.e., with a minor amount of
additives left to be added by the final end consumer. However, for
the purposes of the present specification, in the phrase "additive
package suitable for preparing a fully formulated lubricant
composition" the term "additive package" should be interpreted to
mean the sum total of additives that are used to formulate the
final lubricant or grease or other functional fluid.
[0066] Fluids that can meet the criteria of base oil for lubricant
and functional fluids are varied. They may fall in any of the
well-known American Petroleum Institute (API) categories of Group I
through Group V. The API defines Group I stocks as solvent-refined
mineral oils. Group I stocks contain the most unsaturates and
sulfur and have the lowest viscosity indices. Group I defines the
bottom tier of performance. Group II and III stocks are high
viscosity index and very high viscosity index base stocks,
respectively. The Group III oils contain the lowest level of
unsaturates and sulfur relative to Group I and II oils. With regard
to certain characteristics, both Group II and Group III oils
perform better than Group I, particularly in the area of oxidative
stability and low temperature performance.
[0067] Group IV stocks consist of polyalphaolefins, which can be
produced via the catalytic oligomerization of linear alphaolefins
(LAOs), with particularly preferable LAOs selected from C5-C14
linear alphaolefins, more preferably from 1-hexene to
1-tetradecene, more preferably from 1-octene to 1-dodecene, and
mixtures thereof, although oligomers of lower olefins such as
ethylene and propylene, oligomers of ethylene/butene-1 and
isobutylene/butene-1, oligomers of ethylene with other higher
olefins, such as described in U.S. Pat. No. 4,956,122, and the
patents referred to therein, and the like, may also be used. PAOs
typically offer superior volatility performance, thermal stability,
and pour point characteristics to those base oils in Group I, II,
and III.
[0068] Group V includes all the other base stocks not included in
Groups I through IV. Group V base stocks include, e.g., esters,
alkylated aromatics, polyinternal olefins (PIOs), polyisobutylenes,
polyalkylene glycols (PAGs), etc.
[0069] The additive packages as disclosed herein may be formulated
with any of the above five categories, API Groups I to V, as well
as other materials.
[0070] In preferred embodiments, the additive package includes at
least one ingredient selected from the group consisting of: one or
more sulfur-containing extreme pressure agents, one or more acid
phosphates (pentavalent phosphorus), one or more ashless
dispersants, one or more corrosion inhibitors, and optionally
anti-foamants, pour point depressants, friction modifiers,
demulsifiers, tackifiers, VI improvers, deodorants, seal swell
agents, and non-amine rust inhibitors, and mixtures thereof, with
the proviso that said lubricating compositions are essentially free
of or completely free of: (a) low molecular weight (.ltoreq.C30)
primary, secondary, tertiary, and cyclic hydrocarbyl amines; and
(b) the corresponding acid phosphate amine salts.
[0071] While each of the aforementioned ingredients are per se
known in the art, preferred ingredients are discussed in more
detail below.
[0072] Extreme Pressure Agents
[0073] Extreme pressure (EP) agents used in the composition
according to embodiments of the invention include known
sulfur-containing and boron-containing EP agents. Sulfur-containing
EP agents are preferred.
[0074] Sulfurized olefins are useful in providing protection
against high pressure, metal to metal contacts in industrial and
automotive gear oils. There is no particular restriction on the
sulfur-containing extreme pressure additive that can be used in the
additive package according to embodiments of the invention.
Sulfur-containing components useful in this regard included
sulfurized olefins, dialkyl polysulfides, diarylpolysulfides,
sulfurized fats and oils, sulfurized fatty acid esters, trithiones,
sulfurized oligomers of C2-C8 monoolefins, thiophosphoric acid
compounds, sulfurized terpenes, thiocarbamate compounds,
thiocarbonate compounds, sulfoxides, and thiol sulfinates. Mixtures
of sulfur-containing EP components may be used.
[0075] The preferred sulfur-containing EP components are selected
from sulfurized oligomers of C2-C8 monoolefins, olefins sulfides,
and dialkyl and diaryl polysulfides. The more preferred extreme
pressure agents are oligomeric olefin sulfides and dialkyl
polysulfides. In the most preferred embodiment, the sulfurized
olefin is prepared via a high pressure sulfurization procedure.
[0076] For some gear oil applications, it is possible that
boron-containing EP additives may be adequate, provided that
significant amounts of water are not present to cause hydrolysis.
Use of boron-containing EP agents alone or with sulfur-containing
EP agents is a contemplated aspect of embodiments of the invention.
However, in preferred embodiments of the invention, the composition
does not use an extreme pressure ingredient containing boron.
[0077] Dispersants
[0078] Dispersants serve inter alia to keep sludge and varnish
particles from coating on the gear surfaces. There are no
particular restrictions on the type used, though it is preferable
that at least one contains nitrogen. Nitrogen-containing
dispersants include alkyl succinimides, alkenyl succinimides,
benzylamine compounds (Mannich bases) polybutenylamines, and the
like. Borated versions of any of these are optional.
[0079] In preferred embodiments, nitrogen-containing dispersants
are selected from alkyl succinimides and alkenyl succinimides. The
preferred ashless dispersant for use in this invention are the
products of reaction of a polyethylene polyamine, e.g.
tetraethylene pentamine, with a hydrocarbon-substituted anhydride
made by the reaction of a polyolefin, preferably having a molecular
weight of about 700-5000 and especially 800-3000 (it is not
particularly important whether this is number average molecular
weight or weight average molecular weight) with an unsaturated
polycarboxylic acid or anhydride, e.g. maleic anhydride.
[0080] Borated dispersants are optional and may be formed by
borating ashless dispersants using suitable boron-containing
compounds: boron acids, boron oxides, boron esters, and amine or
ammonium salts of boron acids.
[0081] Corrosion Inhibitors/Metal Passivators
[0082] Corrosion inhibitors or metal passivators are typically
additives that are heterocyclic in nature and are nitrogen-, and
optionally, sulfur-containing Triazole and its derivatives have
been found to prevent corrosion in gear oils. Some specific
examples include benzotriazole, tolyltriazole, 2-mercaptotriazole,
dodecyltriazole. Alkyl and aryl derivatives are preferred.
[0083] A specific class of passivators is known as "copper
passivators." These comprise a class of compounds which includes
thiadiazoles, triazoles, and thiazoles. The preferred compounds are
the 1,3,4-thiadiazoles.
[0084] Phosphate Anti-Wear Agents
[0085] In a preferred embodiment, the additive package includes an
effective amount of at least one mono- and/or dialkyl acid
phosphate for antiwear protection. An "effective amount" can be
determined by one of ordinary skill in the art in possession of the
present disclosure. Preferred mono- and/or dialkyl acid phosphates
antiwear additives include at least one species represented by the
formula (R.sub.1O)(R.sub.2O)P(O)OH, where R.sub.1 is hydrocarbyl
and R.sub.2 is hydrocarbyl or hydrogen. R.sub.1 and R.sub.2 may
have the same or different hydrocarbyl groups. Suitable hydrocarbyl
groups are alkyl groups of 1-40 carbon atoms, preferably 2-20 and
more preferably 3-20. The preferred acid phosphates for use in this
invention are selected from mono- and di-2-ethylhexyl acid
phosphates and mixtures thereof.
[0086] In prior art compositions, acid phosphates would be present
as preformed salts using a low molecular weight hydrocarbyl amine
or the salt would be formed in situ in the additive package and/or
the fully formulated lubricant or grease (or at some other point
between prior to or even during actual use). Such salts are
described in, e.g., U.S. Pat. Nos. 2,063,629, 2,224,695, 2,447,288,
2,616,905, 3,728,260, 3,984,448, and 4,431,552. The hydrocarbyl
amine is often termed a "rust inhibitor" and is usually a low
molecular weight (<30 carbons) primary or secondary amine, but
could also be tertiary or cyclic. The preferred amines are
generally aliphatic in nature and possess from 4-30 carbon atoms.
Some specific examples include the following: octylamine,
decenylamine, dodecenylamine, oleylamine, and the like. In some
cases, the art describes the most preferred amines as a complex
with acid phosphates, where the aliphatic group of the amine is a
tertiary alkyl group and the amine is a primary amine. Primene 81-R
and Primene JMT amines are typically describes as most
preferred.
[0087] The present inventors have surprisingly found that by
eliminating essentially all of the low molecular weight hydrocarbyl
amine "rust inhibitor", and (without wishing to be bound by theory)
the corresponding acid phosphate salt complex, the additive system
will still possess adequate rust performance, even without the
addition of other rust inhibitors and will also have, in at least
some embodiments, at least one improved property selected from
oxidation stability, seal compatibility and antiwear
protection.
[0088] Other additives that may be included in the additive
concentrate include: defoamants, non-aminic rust inhibitors, seal
swell agents, friction modifiers, antioxidants, deodorants,
chromophores, pour point depressants, tackifiers, demulsifiers,
detergents, VI modifiers, and mixtures thereof. One of ordinary
skill in the art, in possession of the present disclosure, can
determine the nature and quantity of additives to provide in the
fully formulated lubricant or grease without undue
experimentation.
[0089] It should be noted that various ingredients may combine with
the other ingredients to form salts, adducts, coordinated species,
and the like. The combination of such species may be formed prior
to addition to the final lubricant fluid, e.g., in the additive
package of embodiments of the invention, such as in situ with a
small amount of diluent (typically the final basestock) or they may
be formed in situ after the ingredients are added to the basestock.
Various combinations are possible. With this in mind, the present
disclosure thus should be read in the nature of a recipe as regards
the various additives described herein.
[0090] Furthermore, although all ingredients added to the final
fully formulated lubricating fluid or greases described herein may
be provided in a single additive package, the term "additive
package" should be taken to mean any one additive package used or
the entire sum of ingredients added to the one or more base oils
used to create the final fully formulated composition.
Examples
[0091] The following examples are meant to illustrate embodiments
of the present invention and provide a comparison with lubricant
formulations which, although heretofore considered adequate for
commercial purposes, are not prepared in accordance with the
present invention. While the examples of the invention are
described with particularity, they should not be taken to limit the
claims. Rather, numerous variations or modifications will become
apparent to (and can be readily made by) those of ordinary skill in
the art in light of these examples, particularly when viewed
together with the entire disclosure.
[0092] For automotive applications, the oils were tested in the rig
tests that are incorporated into API and SAE standards GL-5 and
J2360, respectively. The L-37 test was used to assess antiwear
performance; the L-60-1 was used for oxidative and thermal
stability; and the static seal test ASTM D5662 was run for nitrile,
polyacrylate and fluoroelastomer seal compatibility. The L-42 for
protection against scoring and the L-33 and ASTM D130 for corrosion
protection were also run to demonstrate no deficiencies as a result
of amine elimination. For industrial gear oils, the ASTM D2783 Four
Ball EP test and ASTM D665 for rust were run.
[0093] Automotive Example
[0094] To evaluate a gear lubricant according to embodiments of the
present invention, the axle test ASTM D6121 was employed. This
particular test is more commonly known as the L-37 test and is used
in the industry to evaluate the antiwear performance of an
automotive gear lubricant. This test method measures a lubricant's
ability to protect final drive axles from abrasive wear, adhesive
wear, plastic deformation, and surface fatigue, when subjected to
low-speed high-torque conditions. Lack of protection can lead to
premature gear or bearing failure or both.
[0095] The test apparatus is a new, complete, hypoid truck axle
assembly, Dana Model 60 with 5.86 to 1 ratio. The assembly is
mounted on a test stand with the pinion and axle shafts' center
lines horizontal. The gears are first run through a conditioning
phase and then through a test phase. The test phase is 24 h+0.2 h
and is run at 275.degree. F. with a load of 1740 ft-lb on each
wheel and 80 rpms/min. At the end of the test, the differential is
disassembled and the ring gear and pinion are inspected and rated
for each type of distress (e.g. spalling, pitting, ridging, wear,
rippling, etc.). The rating value is reported.
[0096] This same test method is also used for the Canadian version
of the test, known as the Low Temperature (LT) L-37. The LT L-37
axle test is required for 75W gear oils. This procedure is
identical to the regular temperature L-37, except that the
temperature of the test is run approximately 55.degree. F. lower
during both the conditioning and gear test phase.
[0097] The oxidative and thermal stability were evaluated in ASTM
D5704 or the L-60/L-60-1 test, which is the most common test
procedure for evaluating these features of automotive gear oils.
The test covers the oil-thickening and insoluble/deposit formation
characteristics of the lubricant when subjected to high temperature
oxidizing conditions. For the L-60 test, the candidate lubricant is
heated to 325.degree. F./163.degree. C. for 50 hr in a small gear
box with two lightly loaded spur gears. Air is bubbled through the
oil at a rate of 1 L/hr. The viscosity of the oxidized oil is
measured at the end of the test and compared to the initial value.
The pentane and toluene insolubles are also measured. The L-60-1
test is run in the same manner; however, the carbon-varnish and
sludge are measured along with the insolubles and viscosity
increase.
[0098] For seal compatibility, ASTM D5662 was run. This is a
laboratory test method which evaluates gear oils for compatibility
with various elastomers: nitrile, polyacrylate, and
fluoroelastomer. This method addresses failures that may be caused
by excessive elastomer hardening, elongation loss, and volume swell
and attempts to determine the likelihood that an oil might cause
premature sealing system failures in the field. Specimens are cut
from the elastomer being evaluated and are immersed in oil for 240
hr. Reference oils are run periodically. The test temperature is
dependent on the type of seal material used: 100.degree. C. for
nitrile and 150.degree. C. for fluoroelastomer and polyacrylate. At
the end of 240 hr, the aged elastomer specimens are tested for
changes in hardness, elongation, tensile strength and volume.
[0099] Lubricating compositions, Oils A1 and A2 were prepared in
accordance with the invention, whereas Oils X1 and X2 were
formulated for comparison. The contents of these fluids are shown
in Table 1 below. The additive systems of all examples use
identical components, differing only in percentages. The additive
percentages of X1 and X2 were manipulated to provide the closest
approach to the percent of S, P, and N additives in A1 and A2,
respectively, which is believed to provide the most valid
comparison. The key difference between A1 and X1, and between A2
and X2, is the omission of the hydrocarbyl primary amine rust
inhibitor in examples according to embodiments of the present
invention. The TBNs for the resulting additive concentrates were
calculated using a potentiometric method ASTM D2896. Oils A1 and A2
have a TBN=14.8 and Oils X1 and X2 have a TBN=27.9.
TABLE-US-00001 TABLE 1 Embodiment of Comparison Embodiment of
Comparison Test the Invention Example the Invention Example Oil
Code A1 X1 A2 X2 Additives in Finished Fluid, wt % EP Agent,
Mobilad C-175 3.65 4.24 3.65 4.24 Antiwear - Mobilad C-421 - Acid
Phosphate 1.13 1.37 1.13 1.37 Amine Rust Inhibitor - Primary Amine
(<C30) 0 0.59 0 0.59 Dispersant, Borated and non-borated 3.51
2.00 3.51 2.00 Copper Passivator - thiadiazole 0.54 0.25 0.54 0.25
Other additives (inhibitors, antioxidants, 1.19 1.19 1.19 1.19
defoamants) TBN of Additive System ASTM D2896 14.8 27.9 14.8 27.9 S
in Finished Oil 2.07 2.19 1.95 2.190 P in Finished Oil 0.128 0.157
0.125 0.158 N in Finished Oil 0.14 0.14 0.14 0.11 Basestocks, wt %
PAO 2, 6 cSt 20.0 20.4 26.0 26.4 PAO 150 55.0 55.0 44.0 44.0
Isononyl Heptanoate 15.0 15.0 20.0 20.0 Viscometrics of Finished
Fluid KV 100.degree. C., cSt ASTM D445 19.65 18.04 11.8 11.3 VI
ASTM D2270 216 219 226 229 Brookfield at -40.degree. C., cP ASTM
D2983 21,495 17,300 7,318 6,470
[0100] In the L-60-1 test, Oils A1 and A2 had much improved carbon
varnish ratings compared with Oil X1 and Oil X2. The results are
shown in Table 2. Based on this test alone, the rating results for
Oils X1 and X2 are considered as "failing". FIG. 2 shows
graphically the superior C-V performance of the candidate oils.
Since the cleanliness is related to the C-V rating, it can be
clearly stated that the oils A1 and A2 are cleaner. Also, pentane
and toluene insolubles were non-existent for Oils A1 and A2 but
around 0.3-0.4 mass percent for the oils X1 and X2. The sludge
rating for all four oils was not significantly different.
[0101] An improvement in the seal compatibility was also observed
for Oils A1 and A2 relative to Oil X2 in the seal test ASTM D5662
(testing of X1 was considered superfluous on the basis of the
results for X2). The change in percent elongation was reduced for
both the fluoroelastomer and polyacrylate with Oils A1 and A2 (see
Table 2 for data), which implies that the candidate oils are having
less affect on the elastomer than the comparative Oil X2.
[0102] The oils were evaluated in the ASTM D130 Copper Corrosion
Test as well as in the L-33 Rust Test. The copper strip was rated
1b for all four oils. It is somewhat surprising that formulations
without the prior art aminic rust inhibitor achieves the same
result as the commercially acceptable formulations with the rust
inhibitor. In the L-33 test, all formulations were well above the
pass/fail line of 9.0 as referenced in SAE J2360 (see Table 2 for
data).
[0103] The L-42 test is used for determining the anti-scoring
properties of gear lubricants under high speed and shock
conditions. It is described as having the same effect on gears as
the start of a drag race. The test unit consists of Dana rear axle
44-1 with a gear ratio of 45:11. In a similar fashion as the L-37
test, the gears are mounted on a test stand with the pinion and
axle shafts' center lines horizontal. The gears are put through a
series of accelerations and decelerations against dynamometers
under specified conditions of speed and torque for four cycles. The
gear teeth are inspected at the end of the test for the amount of
scoring on the tooth surface. The amount of scoring must be less
than or equal to the pass reference oil. Both oils were tested and
the data are presented in Table 2. Oils A1 and A2 had acceptable
performance, proving the absence of the low molecular weight
hydrocarbyl amine does not hurt scoring performance.
[0104] These data reveal that the automotive gear oils A1 and A2
had excellent performance, despite missing the rust inhibitor.
Performance was better in areas of oxidation, anti-wear and seal
performance and in areas that one might expect to be problematic,
e.g. rust and copper corrosion, was not affected significantly.
TABLE-US-00002 TABLE 2 Embodiment of Comparison Embodiment of
Comparison Test the Invention Example the Invention Example Oil
Code A1 X1 A2 X2 Copper Corrosion ASTM D130 1b 1b 1b 1b L-37 Test,
Uncoated Gears ASTM D6121 Pinion Ring Pinion Ring Pinion Ring
Pinion Ring Burnish 5 5 5 5 5 5 5 5 Discoloration 6 6 6 6 6 7 6 7
Corrosion 10 10 10 10 10 10 10 10 Deposits 10 9 10 10 10 10 9 9
Wear 6 8 6 7 7 7 6 7 Scoring 10 10 10 10 10 10 10 10 Rippling 8 9 8
9 9 9 8 9 Ridging 8 9 8 9 9 10 8 9 Spitting 9.9 9.9 9.9 9.9 9.9 9.9
9.9 9.9 Overall Merit 8.94 8.92 9.41 8.92 Evaluation Pass Pass Pass
Pass L-37 Test, Uncoated Gears, Low Temp. ASTM D6121 Pinion Ring
Pinion Ring Pinion Ring Pinion Ring Burnish 5 5 5 5 5 5 3 5
Discoloration 6 6 6 6 6 7 6 6 Corrosion 10 10 10 10 10 10 10 10
Deposits 10 9 10 7 10 9 10 8 Wear 6 8 5 6 6 8 5 6 Scoring 10 10 10
10 10 10 10 10 Rippling 9 10 7 9 9 9 6 9 Ridging 9 10 6 6 9 10 6 6
Spitting 9.9 9.9 8.0 9.9 9.9 9.9 9.0 9.9 Overall Merit 9.56 7.66
9.41 7.66 Evaluation Pass Fail Pass Fail L-60-1 Test (n = 1) ASTM
D5704 % Viscosity Increase 35 22 27 18 Pentane Insolubles 0 0.40 0
0.35 Toluene Insolubles 0 0.41 0 0.37 Carbon/Varnish 9.7 5.8 9.8
5.0 Sludge 9.5 9.62 9.7 9.49 Evaluation Pass Fail Pass Fail L-42 %
Scoring Ring, Coast 4 3 4 5 % Scoring Pinion, Coast 6 5 9 8 % of
Pass/Fail Reference 26 24 33 32 Evaluation Pass Pass Pass Pass Seal
Compatibility ASTM D5662 Fluoroelastomer, % elongation change -14.7
nd -12.7 -34.9 Polyacrylate, % elongation change 11.0 nd 28.0 70.5
Nltrile, % elongation change -55.8 nd -53.4 -56.6 L-33-1 Test ASTM
D7038 Merit Rating 9.31 9.91 9.56 9.83 Evaluation Pass Pass Pass
Pass
[0105] Industrial Gear Fluids
[0106] Industrial gear fluids were also formulated in accordance
with embodiments of the present invention and one was tested in an
effort to demonstrate acceptable performance despite the omitted
low molecular weight (.ltoreq.C30) hydrocarbyl amine and the
corresponding phosphate amine salt. Oil B was one such candidate,
i.e. no low molecular weight (.ltoreq.C30) hydrocarbyl amine was
part of the additive system. Here again, the additive package's TBN
was unusually low, measured at 4.5. Table 3 below shows the
composition of the additive system and the mineral base oils that
were employed.
TABLE-US-00003 TABLE 3 Embodiment of Comparison Test the Invention
Example Oil Code B Y Additives in Finished Lubricant, wt % EP
Agent, Mobilad C-170 0.56 0.56 Antiwear - Mobilad C-421 - Acid
Phosphate 0.37 0.37 Amine Rust Inhibitor - Primary Amine (<C30)
0 0.12 Dispersant, Borated and non-borated 0.09 0.09 Copper
passivator - thiadiazole 0.20 0.09 Other additives (inhibitors,
defoamants, 0.046 0.046 demulsifiers) TBN of Additive System ASTM
D2896 4.5 27.8 S in Finished Oil (additive contribution only) 0.275
0.275 P in Finished Oil 0.0440 0.044 N in Finished Oil 0.017 0.015
Basestocks, wt % 150'' Solvent Paraffinic Neutral 12.5 12.5 150
Bright Stock 86.0 86.0 Viscometrics KV, 100.degree. C. ASTM D445
23.6 23.7 KV, 40.degree. C. ASTM D445 306.3 309.3 VI ASTM D2270 97
97
[0107] To evaluate the performance of the industrial gear lubricant
disclosed herein, laboratory bench tests that are part of AIST 224
(formerly USS 224), AGMA 9005-E02, and other common industry
specifications, were employed. Again, antiwear performance and rust
protection were evaluated. ASTM D2783, a Four Ball EP Load Wear
Test, measures the antiwear capability of the gear lubricant. One
steel ball under load is rotated against three stationary balls
immersed in oil. The load is increased until the weld point in
kilograms is determined. The load wear index, an index of the
ability of the lubricant to minimize wear at applied loads, is also
measure. ASTM D4172 uses the Four Ball Test Machine to assess the
wear preventive characteristics of lubricating fluids. A steel ball
is rotated atop of three clamped balls at a rate of 1800 rpms for
60 min under a force of 20 kg at 75.degree. C. The average wear
scar of the three clamped balls is then determined. ASTM D665 is
used to measure protection from steel corrosion. A mixture of test
oil is mixed with either distilled water (Part A) or synthetic sea
water (Part B) at a temperature of 60.degree. C. with a cylindrical
steel rod completely immersed. After four hours, the test rod is
examined for signs of rusting. Copper corrosion performance was
roughly equivalent for the two oils as determined by ASTM D130. The
results for Oil B and comparison Oil Y are shown in Table 4.
TABLE-US-00004 TABLE 4 Embodiment of Comparison Test the Invention
Example Oil Code B Y Copper Corrosion ASTM D130 1a 1b Four Ball
Wear ASTM D4172 Wear Scar, mm 0.31 0.35 Four Ball Weld ASTM D2783
Load Wear Index, kg 53 63 Weld Point, kg 250 250 Rust Test ASTM
D665 Part A Pass Pass Part B Pass Pass
[0108] From these results, one can see there is no significant
detrimental effect for this industrial gear oil when the
hydrocarbyl amine rust inhibitors are omitted from the package. The
rust test ASTM D665 is readily passed with both distilled and salt
water. Copper corrosion protection is also satisfactory for the
candidate fluid based on ASTM D130 results. The antiwear
performance is roughly equivalent as evidenced by the Four Ball
Wear and EP test results.
[0109] The invention has been described above with reference to
numerous embodiments and specific examples. Many variations will
suggest themselves to those skilled in this art in light of the
above detailed description. All such obvious variations are within
the full intended scope of the appended claims. Nevertheless, a few
particularly preferred embodiments may be pointed out. One
particularly preferred embodiment includes an additive package
suitable for preparing a fully formulated lubricating fluid or
grease including an effective amount of an acid
phosphate-containing antiwear additive, the improvement comprising
the absence of primary, secondary, tertiary, and cyclic aliphatic
amines with a carbon number of C30 or less and the absence of the
corresponding acid phosphate amine salts, with still more preferred
embodiments, which may be combined as would be recognized by one of
ordinary skill in the art in possession of the present disclosure,
selected from: (i) wherein said additive package has a TBN<22
(or TBN<20, or TBN<15, or TBN<10, or TBN<5); (ii)
wherein said acid phosphate is selected from at least one mono
and/or dihydrocarbyl ester of an acid phosphate characterized by
the formula (I):
(R.sub.1O)(R.sub.2O)P(O)OH (1)
where R.sub.1 is a hydrocarbyl group and R.sub.2 is selected from
hydrogen or a hydrocarbyl group, which may be still more preferably
characterized by the case where the hydrocarbyl groups of R.sub.1
and R.sub.2 are independently selected from straight-chained or
branched alkyl groups having from 1 to 20 carbon atoms, or from 2
to 20 carbon atoms, or from 3 to 20 carbon atoms, and yet still
more preferably wherein at least one of the hydrocarbyl groups
R.sub.1 and R.sub.2 are 2-ethylhexyl acid phosphate; (iii)
characterized as comprising at least one of the following
ingredients: (a) at least one sulfur-containing extreme pressure
agent; (b) at least one nitrogen-containing dispersant; (c) at
least one corrosion inhibitor; (iv) further comprising at least one
ingredient selected from the group consisting of borated
dispersants, non-aminic rust inhibitors, defoamants, pour point
depressants, antioxidants, demulsifiers, friction modifiers, seal
swell agents, chromophores, deodorants, limited slip additives,
detergents, VI modifiers, and tackifiers. Another particularly
preferred embodiment includes an additive package suitable for use
in driveline fluids and/or gear boxes for industrial applications
characterized as essentially free of primary, secondary, tertiary
and cyclic hydrocarbyl amines with a carbon number of C30 or less
and essentially free of the corresponding acid phosphate amine
salts, more preferably yet wherein said additive package further
comprising an acid phosphate selected from at least one mono and/or
dihydrocarbyl ester of an acid phosphate characterized by the
formula (I):
(R.sub.1O)(R.sub.2O)P(O)OH (1)
where R.sub.1 is a hydrocarbyl group and R.sub.2 is selected from
hydrogen or a hydrocarbyl group, and still more preferably at least
one of the cases wherein: (i) at least one of the hydrocarbyl
groups R.sub.1 and R.sub.2 are 2-ethylhexyl; (ii) wherein the
composition is further characterized as comprising at least one of
the following ingredients: (a) at least one sulfur-containing
extreme pressure agent; (b) at least one nitrogen-containing
dispersant; (c) at least one corrosion inhibitor.
[0110] Unless specified otherwise herein, the meanings of terms
used herein shall take their ordinary meaning in the art; reference
shall be taken, in particular, to Synthetic Lubricants and
High-Performance Functional Fluids, Second Edition, Edited by
Leslie R. Rudnick and Ronald L. Shubkin, Marcel Dekker (1999). This
reference, as well as all patents and patent applications, test
procedures (such as ASTM methods and the like), and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this invention and for all
jurisdictions in which such incorporation is permitted. Note that
Trade Names used herein are indicated by a .TM. symbol or .RTM.
symbol, indicating that the names may be protected by certain
trademark rights, e.g., they may be registered trademarks in
various jurisdictions. Note also that when numerical lower limits
and numerical upper limits are listed herein, ranges from any lower
limit to any upper limit are contemplated.
* * * * *