U.S. patent application number 11/387196 was filed with the patent office on 2006-10-26 for corrosion protection for lubricants.
Invention is credited to Ellen B. Brandes, William Sullivan, Shi-Ming Wu.
Application Number | 20060240998 11/387196 |
Document ID | / |
Family ID | 36118102 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060240998 |
Kind Code |
A1 |
Sullivan; William ; et
al. |
October 26, 2006 |
Corrosion protection for lubricants
Abstract
The present invention relates to compositions comprising at
least one triazole-containing species and at least one
thiadiazole-containing species, which in embodiments are suitable
for manual transmission oils.
Inventors: |
Sullivan; William; (Brick,
NJ) ; Wu; Shi-Ming; (Dayton, NJ) ; Brandes;
Ellen B.; (Bound Brook, NJ) |
Correspondence
Address: |
ExxonMobil Chemical Company;Law Technology
P.O. Box 2149
Baytown
TX
77522-2149
US
|
Family ID: |
36118102 |
Appl. No.: |
11/387196 |
Filed: |
March 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60673858 |
Apr 22, 2005 |
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Current U.S.
Class: |
508/269 ;
508/243 |
Current CPC
Class: |
C10M 141/10 20130101;
C10M 2215/225 20130101; C10N 2030/06 20130101; C10N 2020/02
20130101; C10M 141/08 20130101; C10N 2020/00 20130101; C10N 2060/14
20130101; C10M 2215/223 20130101; C10M 2215/28 20130101; C10M
169/044 20130101; C10M 2205/0265 20130101; C10M 169/04 20130101;
C10N 2040/04 20130101; C10M 141/12 20130101; C10N 2040/044
20200501; C10N 2040/08 20130101; C10M 2215/04 20130101; C10N
2030/12 20130101; C10M 2219/106 20130101; C10M 2205/0206 20130101;
C10M 2219/022 20130101; C10M 2223/04 20130101; C10M 2223/041
20130101; C10M 2223/04 20130101; C10M 2223/04 20130101 |
Class at
Publication: |
508/269 ;
508/243 |
International
Class: |
C10M 135/32 20060101
C10M135/32 |
Claims
1. A lubricant composition suitable for use as a lubricating oil,
said composition comprising at least one triazole-containing
species and at least one thiadiazole-containing species.
2. The composition of claim 1, comprising at least one
triazole-containing species and at least one species from the group
consisting of dimercaptothiadiazole and alkylated derivatives
thereof.
3. The composition of claim 1, where the triazole-containing
species is tolyltriazole.
4. The composition according to claim 1, further characterized by a
ratio of thiadiazole-containing species to triazole-containing
species of from about 20:1 to about 1:10.
5. The composition according to claim 4, wherein the ratio of
thiadiazole-containing species to triazole-containing species is
from about 10:1 to about 1:1.
6. The composition according to claim 1, further comprising at
least one ingredient selected from (i) at least one
sulfur-containing or boron-containing extreme pressure agent; and
(ii) at least one phosphorus-containing antiwear agent.
7. The composition according to claim 1, further characterized by
having a ratio of sulfur to triazole-containing species of less
than about 150:1.
8. The composition of claim 1, further characterized by having a
ratio of sulfur to triazole-containing species of less than about
100:1.
9. The composition according to claim 1, further comprising
ingredients selected from extreme pressure agents, antiwear agents,
dispersants, detergents, rust inhibitors, corrosion inhibitors,
anti-foaming agents, demulsifiers, pour point depressants, seal
swell agents, emulsifiers, tackifiers, antioxidants, VI improvers,
thickening agents, and mixtures thereof.
10. A lubricant composition of claim 1 comprising at least one
basestock selected from API Groups I-V.
11. An automotive transmission oil, industrial oil, industrial gear
oil, hydraulic fluid, tractor oil comprising the lubricant
composition of claim 1.
12. A manual transmission oil comprising the lubricant composition
of claim 1.
13. The manual transmission oil of claim 12, wherein said basestock
comprises at least one basestock selected from API Groups I-V.
14. The manual transmission oil of claim 12, wherein said basestock
composition is selected from API Group IV, API Group V, and
mixtures thereof.
15. The manual transmission oil of claim 12, wherein said basestock
composition is selected from API Group IV.
16. The manual transmission oil of claim 12, wherein said basestock
composition comprises 2 cSt and 150 cSt PAO.
17. The manual transmission oil of claim 12, wherein said basestock
composition comprises 4 cSt PAO and 150 cSt PAO.
18. The manual transmission fluid of claim 12, further comprising
polyisobutylene and one of: (a) a 2 cSt PAO and a 150 cSt PAO; or
(b) a 4 cSt PAO and a 150 cSt PAO.
19. In a lubricating fluid comprising a corrosion inhibitor, the
improvement comprising the presence of an effective amount of a
combination of a triazole-containing species and a
thiadiazole-containing species.
20. A vehicle comprising a manual transmission, said manual
transmission lubricated by a composition according to claim 11.
21. A transmission lubricated by the compositions of claim 1.
22. A transmission lubricated by the lubricating fluid of claim
19.
23. A method of preparing a lubricating composition comprising
combining the composition of any one of claim 1 with at least one
basestock selected from API Group I-V.
24. A method of lubricating a transmission comprising adding a
composition according to claim 23 to a transmission.
25. A composition comprising at least one thiadiazole-containing
species and at least one triazole-containing species in the ratio
of about 20:1 to about 1:10.
26. The composition according to claim 25, wherein said ratio is
about 10:1 to about 1:1.
27. The composition according to claim 1, further comprising at
least one ingredient selected from (i) at least one
sulfur-containing or boron-containing extreme pressure agent; and
(ii) at least one phosphorus-containing antiwear agent.
28. A fully formulated lubricant composition based on S, P
chemistry comprising at least one thiadiazole-containing species
and at least one triazole-containing species in the ratio of about
20:1 to about 1:10.
29. The fully formulated lubricant composition of claim 28, wherein
said ratio is about 10:1 to about 1:1.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Provisional
Application No. 60/673,858 filed Apr. 22, 2005, the disclosure of
which is incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to lubricating compositions and other
functional fluids. The compositions comprise at least one
triazole-containing species and at least one thiadiazole-containing
species. In preferred lubricating compositions, at least one
extreme pressure (EP) component and at least one
phosphorus-containing antiwear component are also present. In
preferred embodiments the compositions are particularly useful in
manual transmission oils.
BACKGROUND OF THE INVENTION
[0003] Emerging industry requirements for manual transmission
fluids in the areas of micropitting and corrosion protection have
created a need for new lubricant compositions. In order to meet
these requirements, new additive systems suitable for blending with
appropriate base stocks are needed. It is desirable that these new
requirements be met without detracting from the positive properties
of current lubricant compositions, particularly properties relating
to oxidative and thermal stability, load carrying/antiwear
performance, seal compatibility, and the like.
[0004] Manual transmission fluids, otherwise known as manual
transmission oils or MTOs, are typically used in automobiles, light
trucks, and heavy duty trucks. The torque from the engine is
transferred directly to the driveline through mechanical clutch and
speed increasing/reducing gears, e.g., spur gears. The fluids that
lubricate such gears need to possess a variety of conventional
features: extreme pressure (EP) performance for load carrying,
antiwear performance, yellow metal corrosion protection, rust
inhibition, foam suppression, thermal and oxidative stability,
cleanliness, seal compatibility, among others. EP components,
typically based on sulfur (S) and/or boron (B), and antiwear
components, typically based on phosphorus (P), are therefore often
part of lubricant compositions. Examples of such additives are
disclosed in numerous patents, such as U.S. Pat. Nos. 4,900,460;
5,500,140; 5,547,596; 5,691,283; 5,756,429; 6,046,144; 6,605,572;
U.S. Patent Application No. 2003/0176299; WO 03/104620; EP 1422287;
EP 391653; EP 531000; EP 450208; and EP 531585.
[0005] However, corrosion may be seen in the field with the use of
S, P-based lubricants, particularly when copper-containing
components, e.g. coolers, are employed. Consequently, OEMs are
issuing specifications which make it difficult for formulators to
use S, P-containing additives. Therefore, many have stopped using
S, P-containing additive systems because of corrosion issues.
[0006] New demands with respect to micropitting, corrosion
protection and durability are placing severe demands even on MTOs
not using S, P chemistry. Original Equipment Manufacturers (OEMs)
are requiring proof of performance in new micropitting tests and
extended corrosion tests, while also expecting to see maintained or
improved EP and antiwear protection over longer periods of time.
Consequently, extended drain intervals, improved durability, and
enhanced corrosion and micropitting protection are key features
required of new transmission fluids. Conventional S, P packages
struggle to meet a satisfactory level of performance.
[0007] Given the enormous number of ingredients proposed for
additive packages, it is a formidable task to find the right
combination capable of meeting the number of new requirements
desired in driveline fluids such as MTOs while maintaining
traditional performance standards in other areas. Numerous attempts
have been made to improve corrosion problems in formulations based
on S, P chemistry.
[0008] U.S. Pat. No. 4,511,481 discloses industrial lubricants
stabilized with a triazole adduct of amine phosphates, providing
oxidation stability, antiwear, and rust preventative
performance.
[0009] Dimercaptothiadiazole derivatives, such as
2,5-dimercapto-1,3,4-thiadiazole, disodium
2,5-dimercaptothiadiazole, and 2,5-bis(t-nonyl-dithio) thiadiazole,
are known for their antioxidancy, anticorrosion, and metal
passivation properties as disclosed in, for instance, U.S. Pat.
Nos. 4,382,869, 4,661,273, 4,678, 592 and 4,584,114.
[0010] Furthermore, U.S. Pat. No. 5,186,850 discloses that the
incorporation of the heterocyclic dimercaptothiadiazole
functionality into succinimide structures provides ashless
dispersants with multifunctional antiwear, antioxidant and
corrosion inhibitor properties in lubricant compositions.
[0011] U.S. Pat. No. 5,205,945 describes a multifunctional
antioxidant, antiwear, and dispersancy additive for fuels and
lubricants is a reaction product of a thiol-substituted diazole,
such as aminomercaptothiadiazole (AMTD) or dimercaptothiadiazole
(DMTD), an aldehyde and a hydrocarbon-substituted succinimide
dimer.
[0012] U.S. Pat. No. 5,538,652 is directed to combinations of
dimercaptothiadiazole-mercaptan coupled dithio compounds with
amines which have proven to be highly effective multifunctional
antiwear/extreme pressure additives for lubricants and fuels.
[0013] U.S. Pat. No. 6,180,575 discloses a lubricating oil having
additives comprising an adduct of a substituted triazole with an
amine phosphate in order to balance anti-wear and anti-rust
properties. See also WO 2000/08119.
[0014] The present inventors have discovered a composition which,
in preferred embodiments in combination with suitable basestocks,
is able to meet the newest industrial requirements for MTOs without
sacrificing the positive attributes of currently available
commercial products.
SUMMARY OF THE INVENTION
[0015] The lubricant composition of the invention comprises a
combination of at least one triazole-containing species and at
least one species selected from a thiadiazole-containing species.
In embodiments the invention provides improved corrosion protection
for manual transmissions.
[0016] In other embodiments, the composition will also include one
or more ingredients selected from: (a) at least one extreme
pressure (EP) component selected from sulfur-containing component;
and (b) at least one phosphorus-containing antiwear component. In
embodiments comprising at least one sulfur-containing EP component,
a preferred composition is characterized by a mass ratio of sulfur
to that of the triazole-containing species of less than or equal to
150:1.
[0017] In even more preferred embodiments, lubricant compositions
comprising alkyl polysulfides and alkyl phosphate esters, in
combination with a triazole-containing corrosion inhibitor, such as
tolyl triazole and dimercaptothiadizole, have been found
particularly effective in avoiding corrosion of copper.
[0018] In other embodiments the lubricant composition of the
invention will comprise a dispersant and/or a rust inhibitor, and
optionally other ingredients.
[0019] The invention is also directed, in preferred embodiments, to
formulated MTOs comprising at least one basestock selected from API
Group I through V basestocks and an additive system. In more
preferred embodiments, the invention is directed to formulated MTOs
comprising at least one API Group IV and/or Group V basestock and
an additive system.
[0020] It is an object of the invention to provide lubricating oils
containing high levels of sulfur that do not significantly corrode
yellow metals.
[0021] It is another object of the invention to provide a lubricant
formulation based on S, P chemistry that provides high temperature
copper corrosion resistance.
[0022] It is still another object of the invention to provide
improvements in the area of micropitting and load carrying/antiwear
protection.
[0023] 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.
DETAILED DESCRIPTION
[0024] According to the invention, a lubricant composition is
provided comprising a combination of at least one triazole,
triazole derivative, or salt thereof, referred to herein as
"triazole-containing species", and at least one species selected
from a thiadiazole-containing species.
[0025] In embodiments, the lubricant composition will also include
ingredients selected from: at least one extreme pressure (EP)
component selected from sulfur-containing and/or boron-containing
species; and at least one phosphorus-containing antiwear
component.
[0026] In embodiments comprising at least one sulfur-containing EP
component, a preferred lubricant composition is characterized by a
mass ratio of sulfur to triazole-containing species of less than or
equal to 150:1.
[0027] Additional embodiments are described herein below.
[0028] Critical ingredients are selected from the following
materials.
[0029] A. Triazole-Containing Species.
[0030] A key ingredient in the lubricant composition according to
the invention is a triazole, triazole derivative, or salt thereof,
referred to herein as "triazole-containing species". Preferred
triazole-containing species include those known in the art per se
as corrosion-inhibiting agents. While the exact amount used is not
critical, an effective amount should be used. This may be
determined by one of ordinary skill in the art in possession of the
present disclosure. Typically, the amount of triazole and/or
derivative used will depend on the level of sulfur-containing EP
agent(s). Appropriate amounts may be determined by one of ordinary
skill in the art in possession of the present disclosure without
more than routine experimentation.
[0031] Triazoles, e.g., 1,2,4-triazole, 1,2,3-triazoles, and their
derivatives and salts, several of which are commercially available
(from, for example, Aldrich Chemicals) have been found to be
important for reducing bearing wear in industrial gear oils and
preventing corrosion in manual transmissions. Since triazole itself
is difficult to solubilize in oil or in an additive mix, it
advantageously can be derivatized. The derivatives provide a means
for making the triazole group more soluble in oil but retain its
corrosion and wear reducing properties. Some specific examples of
derivatives include: benzotriazole, tolytriazole, octyltriazole,
decyltriazole, dodecyltriazole, 2-mercaptobenzotriazole.
[0032] Alkyl and aryl derivatives of triazoles are preferred. Most
preferred is the tolyltriazole.
[0033] Any species containing the triazole species is useful in the
composition according to the invention. The prior art described in
the Background section above lists numerous triazole-containing
species useful in the present invention. In addition, any of the
triazoles mentioned above, including those set forth in the prior
art, may also be present as carboxylic acid salt, e.g the salt of a
fatty acid, like oleic acid or the salt of polybutenyl succinic
acid. Adducts containing triazole species may also be used, e.g.,
amide derivatives prepared by reacting a carboxylic acid with the
amine of the triazole, are also included in the scope of this
invention.
[0034] Additionally, the triazole can also be present in the form
of a salt of one of the phosphorus acid species described below. A
particularly preferred embodiment of the invention is the complex
of the triazole derivative with an alkyl or aryl acid
phosphate.
[0035] B. Thiadiazoles
[0036] At least one thiadiazole-containing species must be present
in a composition according to the present invention. While the
exact amount used is not critical, an effective amount should be
used. This may be determined by one of ordinary skill in the art in
possession of the present disclosure without more than routine
experimentation.
[0037] Preferred thiadiazoles include dimercaptothiadiazole (DMTD)
and its alkylated derivatives, known per se as a class of copper
corrosion inhibitors. Specific examples of the thiadiazoles include
2-mercapto-1,3,4-thiadiazole,
2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles,
2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,
2,5-bis-(hydrocarbylthio)-1,3,4-thiadiazoles, and
2,5-bis-(hydrocarbyldithio)-1,3,4-thiadiazoles. The preferred
compounds are the 1,3,4 thiadiazoles, especially the
2-hydrocarbyldithio-5-mercapto-1,3,4-dithiadiazoles and the
2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazole. Several of these are
commercially available, e.g. Afton Hitec.TM. 4313 and Mobilad.TM.
C-610.
[0038] Other suitable inhibitors of copper corrosion that may be
used along with the required thiadiazoles and the triazoles include
thiazoles, imidazolines, ethoxylated phenols and alcohols, and the
like. However, the present inventors have discovered that the
critical ingredients to assist in meeting at least one object of
the invention, at least in preferred formulated lubricant
compositions, is the presence of the triazole-containing species in
combination with the thiadiazole-containing species.
[0039] These critical species, as well as any optional ingredients,
may be delivered separately or in combination as an additive
package, with or without additional components, to a basestock, to
make a lubricant composition or other functional fluid.
[0040] Preferred optional ingredients in a formulated lubricant
composition according to the invention, include at least one of the
following species set forth in C., D. or E., below. Typically
mixtures of at least one ingredient selected from each of the
following groups will be included.
[0041] C. Extreme Pressure Agents
[0042] Extreme pressure (EP) agents useful in the composition
according to the invention include known sulfur-containing and
boron-containing EP agents. Sulfur-containing EP agents are
preferred.
[0043] Sulfurized olefins are known per se to be useful to provide
protection against high pressure, metal-to-metal contacts in
industrial and automotive gear oils. However, the presence of
sulfurized olefins for this purpose must be balanced against the
drawback that the presence of sulfur lowers thermal stability,
increases the aggression against certain seal materials, and
increases corrosivity toward copper-containing alloys.
[0044] There is no particular restriction on the sulfur-containing
extreme pressure additive that can be used in the additive package
of the invention. Sulfur-containing components useful in this
regard include 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.
[0045] The preferred sulfur-containing EP components are selected
from sulfurized oligomers of C2-C8 monoolefins, olefin sulfides and
dialkyl and diaryl polysulfides.
[0046] A very large number of sulfurized olefins suitable for use
as extreme pressure agents are detailed in the prior art. See, for
instance, U.S. Pat. No. 6,844,300 and references cited therein.
[0047] The more preferred extreme pressure agents are oligomeric
olefin sulfides and dialkyl polysulfides. Oligomeric olefin
sulfides are prepared via the reaction of sulfuryl monochloride
with an olefin, e.g. isobutylene, to create an oligomeric olefin
sulfide compound. The drawback to these materials is the residual
chlorine, which the process leaves behind, but this can be reduced
by various treatments. U.S. Pat. Nos. 2,249,312; 2,708,199;
3,471,404; 4,204,969; 4,563,302; 4,954,274; and 4,966,720 and
European Patent No. 737,674A2 and British Patent No. 1,308,894
describe the preparation of these sulfurized olefins.
[0048] Dialkyl polysulfides are prepared via a high pressure
sulfurization procedure such as described in U.S. Pat. Nos.
4,119,550; 4,119,549; 4,344,854; 5,135,670; and 5,338,468. These
may be prepared, for instance, by the reaction of sulfur, an
olefin, and hydrogen sulfide, which may be provided in situ or
added from an external source. The preferred method for the purpose
of providing an extreme pressure agent for use in the additive
package of the present invention involves generating the hydrogen
sulfide in situ. In a more preferred embodiment, hydrogen sulfide
is formed in the reactor from sodium hydrogen sulfide and consumed
within the reactor.
[0049] In a more preferred embodiment, the high pressure sulfurized
olefin is prepared by reacting an olefin, preferably isobutylene,
with molten sulfur in predetermined quantities in the presence of
aqueous sodium hydrogen sulfide under high pressure conditions.
Commercially available high pressure sulfurized isobutylene (HPSIB)
include Mobilad.TM. C-170 and Mobilad.TM. C-175. The synthesis of
these preferred HPSIBs have been described in the prior art, such
as U.S. Pat. No. 5,135,670 and WO 92/03524, and elsewhere.
[0050] While not critical to the characterization of the present
invention, in a preferred embodiment, the weight percent of sulfur
contributed by additives in any form in the lubricant is 0.1-3 wt
%, more preferably 0.2-2.0 wt %.
[0051] Boron-containing EP agents are also per se known in the art.
However, boron-containing EP agents appear to have deficiencies in
the area of hydrolytic stability, so if a gear box is exposed to
water, the boron-containing EP agents may be hydrolyzed and lose
their effectiveness as EP components. Also, the EP properties may
be less relative to some sulfurized olefins, and therefore for
certain driveline applications, sulfurized olefins may be added
along with the boron-containing additives. In manual transmissions,
it is possible that boron-containing EP additives may be adequate,
if there is no water present. In embodiments, a mixture of
boron-containing and sulfurized olefins may be used as EP
components. However, in preferred embodiments, the composition
according to the present invention does not use an extreme pressure
ingredient containing boron.
[0052] D. Phosphorus-Containing Antiwear Agents
[0053] There is no particular restriction on the type of phosphorus
containing compounds. Oil soluble antiwear and/or extreme pressure
agents that are typically used in industrial gear and drivelines
fluids are for the most part partially or full esterified acids of
phosphorus. All of these are considered for this invention. They
can include the following: acid phosphates, hydrogen phosphites,
phosphites, phosphates, phosphonates, phosphinates, and
phosphoroamidates. They can also include the sulfur analogs of all
of these. Examples include mono, di and trihydrocarbyl phosphites;
mono, di, and trihydrocarbyl phosphates; mono, di, and
trihydrocarbyl mono, di, tri, tetrathiophosphates; mono, di,
trihydrocarbyl mono, di, tri, tetrathiophosphites; various
hydrocarbyl phosphonates and thiophosphonates; various hydrocarbyl
phosphonites and thiophosphonites, etc. Specific examples include
tricresyl phosphate, tributylphosphite, triphenyl phosphite,
di-2-ethylhexyl phosphate, di-isooctyl phosphate,
diisobutylhydrogen phosphite, diisopropyl dithiophosphate, diphenyl
phosphate, etc. All of the amine salts that can be formed with
these materials are also included and the types of amines that can
be used are described in a later section. The preferred embodiments
are the mono and di-alkyl acid phosphates, e.g. mono and
di-2-ethylhexyl phosphoric acid and mono and diaryl phosphates,
e.g. Irgalube 349 from Ciba, and their amine salts.
[0054] While not critical to the characterization of the present
invention, in a preferred embodiment the level of elemental
phosphorus in the formulated lubricant composition according to the
invention is about 0.01-1 wt %, more preferably 0.03-0.5 wt %.
[0055] E. Other Optional Ingredients
[0056] Other ingredients such rust inhibitors, dispersants and/or
cleanliness agents, antioxidants, defoamants, additional metal
corrosion prevention agents (e.g. copper passivators), friction
modifiers, seal swell agents, pour point depressants, diluents, and
the like, may be present to provide the required oil attributes. As
with the other optional ingedients listed in C. and D., above,
these optional ingredients are part of a fully formulated lubricant
or other functional fluid, or a combination thereof. Again, the
effective amount of these optional ingredients may be determined by
one of ordinary skill in the art in possession of the present
disclosure.
[0057] A preferred but optional additive is a rust inhibitor. Rust
inhibitors may be any oil-soluble basic amine or combinations of
amines. The amines can be primary, secondary, tertiary, acyclic or
cyclic, mono or polyamines. They can also be heterocyclic. The
amine-containing components can also contain other substituents,
e.g. ether linkages or hydroxyl moieties. The preferred amines are
generally aliphatic in nature. Some specific examples include:
octylamine, decylamine, C10, C12, C14 and C16 tertiary alkyl
primary amines (or combinations thereof), laurylamine,
hexadecylamine, heptadecylamine, octadecylamine, decenylamine,
dodecenylamine, palmitoylamine, oleylamine, linoleylamine,
di-isoamylamine, di-octylamine, di-(2-ethylhexyl)amine,
dilaurylamine, cyclohexylamine, 1,2-propylene amine,
1,3-propylenediamine, diethylene triamine, triethylene tetraamine,
ethanolamine, triethanolamine, trioctylamine, pyridine, morpholine,
2-methylpiperazine, 1,2-bis(N-piperazinyl-ethane),
tetraminooctadecene, triaminooctadecene, N-hexylaniline and the
like. They may also be triazole or triazole derivatives which are
described elsewhere as a necessary ingredient in a composition
according to the present invention.
[0058] The most preferred amines for this invention to serve as
rust inhibitors are oil-soluble aliphatic amines in which the
aliphatic group is a tertiary alkyl group. Exemplary of such amines
include Primene.TM. 81R and Primene.TM. JMT, commercially available
from Rohmax.
[0059] It should be noted that in a formulated lubricant
composition according to the invention, as would be recognized by
one of skill in the art in possession of the present disclosure,
amines combine with the acid phosphates to form salts, which are
also effective as antirust and antiwear agents. The salts of the
phosphates and amines may be formed prior to addition to the
lubricant composition or they may be formed in situ after the acid
phosphate and amine are added to the additive package or to the
formulated lubricant.
[0060] Amides, imides, and imidazolines, oxazolidones, and other
related nitrogen-containing species can also be present as rust
inhibitors, friction modifiers, or to serve some other purpose.
Some examples of these include the reaction products of
dodecenylsuccinic anhydride (DDSA) and tetraethylene pentamine, the
reaction products of oleic acid and tetraethylene pentamine, the
reaction products of diethylene triamine and DDSA, the reaction
products of triethanolamine and nonanoic acid and the like.
[0061] A preferred but optional additive is at least one dispersant
and/or cleanliness agent. Dispersants serve inter alia to keep
sludge and varnish particles from coating on the gear surfaces.
Numerous such agents are per se known in the art. There are no
particular restrictions on the type to be used. They may be used
singly or in combinations. They may be borated, partially borated
or unborated. Typical examples of nitrogen-containing dispersants
include alkylsuccinimides, alkenylsuccinimides, boron-containing
alkylsuccinimides, boron-containing alkenylsuccinimides,
benzylamines compounds (Mannich bases), polybutenylamines, succinic
acid ester compounds, and the like.
[0062] In preferred embodiment, nitrogen-containing dispersants are
selected from alkylsuccinimides, alkenylsuccinimides, and the
boron-containing analog of both of these. The especially preferred
ashless dispersants for use in this invention are the products of
reaction of a polyethylene polyamine, e.g. triethylene tetraamine
pentaamine, with a hydrocarbon-substituted anhydride made by the
reaction of a polyolefin, preferably 700-1400 and especially
800-1200 with an unsaturated polycarboxylic acid or anhydride, e.g.
maleic anhydride. The ashless dispersants can be borated to form
ashless boron-containing dispersants using suitable
boron-containing compounds: boron acids, boron oxides, boron
esters, and amine or ammonium salts of boron acids.
[0063] Another preferred but still optional ingredient in the
composition according to the invention include an antioxidant to
protect the composition and reduce the decomposition by oxygen,
especially at elevated temperatures. Typical antioxidants include
hindered phenolic antioxidants, secondary aromatic amine
antioxidants, and sulfurized phenolic antioxidants. Specific
examples include diphenylamines, alkylated diphenylamines,
phenyl-alpha-napthylamines, and t-butylphenol derivatives, styryl
phenol and its derivatives. Note that one of the most common
classes of antioxidants are the nitrogen-containing antioxidants,
e.g, aromatic amine antioxidants such as diphenylamines, alkylated
diphenylamines, and phenyl-.alpha.-napthylamines.
[0064] Anti-foam agents are also a preferred but still optional
ingredient, useful to prevent or reduce the formation of stable
foam. Typical anti-foam agents include silicone or organic polymers
such as acrylate polymers. Some specific examples of anti-foam
agents include polymethylacrylate and polybutylacrylate. One such
alkylacrylate polymeric defoamer, Mobilad C-402, is commercially
available from ExxonMobil Chemical Company. As an alternative, the
anti-foaming ingredient may be added to the finished lubricant
rather than or in addition to adding it to the additive package.
Additional antifoam compositions are described in "Foam Control
Agent," by Henry T. Kerner (Noyes Data Corporation, 1976, pp
125-162).
[0065] Other ingredients that may be included are detergents, both
metal and non-metal-containing, seal swell agents, friction
modifiers, anti-chatter agents, and the like.
[0066] While the formulated lubricant composition, including
necessary ingredients and optional ingredients, has been set forth
in detail above, it will be understood by one of ordinary skill in
the art that typically the above ingredients will be blended into
an additive package or add pack which the oil formulators will add
to a basestock or other fluids, e.g., carrier, hydraulic fluid,
solvent, etc.
[0067] Regarding the mass ratio of sulfur to triazole-containing
species, while not critical to a composition according to the
invention, in embodiments it is 150:1 or less and in preferred
embodiments it is 100:1 or less and still more preferred
embodiments, it is 75:1 or less. Again, while not critical to the
description, provided effective amounts of the required
triazole-containing species is present, in embodiments the lower
limit of sulfur to triazole derivative will be about 10:1. It will
be recognized that certain basestocks may contain appreciable
amounts of sulfur-containing species and the amount of sulfur
contributed by the basestock should not be included in the
aforementioned ratio.
[0068] The additives may be combined in whole or in part into an
additive package, or they may be added separately to the final
lubricant composition or other functional fluid. The blending
operations in any of these cases do not need to be complex. They
may involve simply mixing together in suitable proportions all the
appropriate components. Those who are skilled in the art would be
familiar with suitable procedures and for formulating and blending
additive concentrates and lubricant compositions. Generally
speaking, the order of addition is not critical unless in order to
control exotherms it is necessary to alter the order, which may be
determined by one of skill in the art without more than routine
experimentation. Without wishing to be overly pedantic, agitation
with a mechanical stirrer is typically desirable to facilitate
blending. Some practitioners may wish to apply heat while blending.
Generally, heating the blend between 40.degree. and 100.degree. C.
will be sufficient. Naturally, the temperatures should be chosen so
as not to cause any unwanted chemical reactions or thermal
degradation. Blending under an inert atmosphere may be beneficial.
Blending the finished lubricants is equally as straightforward.
[0069] Base oils
[0070] Note that the terms basestock and base oil are used
interchangeably herein. Fluids that can meet the criteria of base
oil for lubricant and functional fluids are varied. They may fall
into 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 lubricant performance. Group II
and III stocks are high viscosity index and very high viscosity
index base stocks, respectively. The Group III oils contain fewer
unsaturates and sulfur than the Group II oils. With regard to
certain characteristics, both Group II and Group III oils perform
better than Group I oils, particularly in the area of thermal and
oxidative stability.
[0071] Group IV stocks consist of polyalphaolefins, which are
produced via the catalytic oligomerization of linear alphaolefins
(LAOs), particularly LAOs selected from C5-C14 alphaolefins,
preferably from 1-hexene to 1-tetradecene, more preferably from
1-octene to 1-dodecene, and mixtures thereof, with 1-decene being
the preferred material, although oligomers of lower olefins such as
ethylene and propylene, oligomers of ethylene/butene-1 and
isobutylene/butene-1, and oligomers of ethylene with other higher
olefins, as described in U.S. Pat. No. 4,956,122 and the patents
referred to therein, and the like may also be used. PAOs offer
superior volatility, thermal stability, and pour point
characteristics to those base oils in Group I, II, and III.
[0072] Group V includes all the other base stocks not included in
Groups I through IV. Group V base stocks includes the important
group of base stocks based on or derived from esters. It also
includes alkylated aromatics, polyinternal olefins (PIOs),
polyalkylene glycols (PAGs), etc.
[0073] One of the great benefits of the present invention is that
it is applicable to base oils fitting into any of the above five
categories, API Groups I to V, as well as other materials. As used
herein, whenever the terminology "Group . . . " (followed by one or
more of Roman Numerals I through V) is used, it refers to the API
classification scheme set forth above.
[0074] Such additional but optional ingredients that may be
beneficial in the final lubricant or functional fluid composition
that are typically not classified in the art as "additive" per se
but are included in this scope of this invention are pour point
depressants, viscosity index modifiers, thickeners, e.g.
polyisobutylene, and tackifiers.
[0075] The following examples are meant to illustrate the present
invention in more detail and provide a comparison with other
methods and the products produced therefrom. Numerous modifications
and variations are possible and it is to be understood that within
the scope of the appended claims, the invention may be practiced
otherwise than as specifically described herein.
[0076] Manual Transmission Oils (MTOs)
[0077] The additive-containing lubricant compositions described in
the preceding sections are useful for manual transmission oil
formulations.
[0078] Manual transmission fluids generally will possess the same
set of features that many other lubricants need to have: extreme
pressure/anti-wear performance, metal corrosion protection,
frictional features, seal compatibility, cleanliness, thermal and
oxidative stability, antioxidancy, foam control, pour point
depression. In addition, current MTOs in North America need to have
exceptional corrosion protection, which is difficult for S, P
systems. New MTOs must also possess satisfactory protection against
micropitting. To accomplish this, lubricant compositions were
prepared containing the key ingredients: a triazole-containing
derivative and a thiadiazole-containing derivative. In addition,
the fluids contained an extreme pressure additive chosen from
sulfurized isobutylene and a P-containing antiwear additive. PAO
and ester were used as base oils. The fluid was tested against
several of the key performance tests in the proposed Eaton PS 164
rev 7 specification, which is known in the art.
[0079] The following examples of lubricant compositions of the
present invention show a significant improvement over conventional
gear and transmission lubricants. A series of lubricant
compositions were prepared using synthetic base stocks. The
additives included in each composition are listed in Table 1 and
include extreme pressure, antiwear, anti-corrosion, cleanliness,
etc. agents. The three extreme pressure additives used differ in
their sulfur content. The first contains a level of sulfur ranging
from 47-52 wt %; the second from 45-49 wt %; the third from 41-46
wt %. The base stocks used in examples A-E and comparative examples
F and G include the following: 2 or 4 centistoke (cSt)
polyalphaolefin (PAO), a shear stable polyisobutylene, e.g. BP's
Indopol.TM. H-300, and a high viscosity 150 cSt PAO, commercially
available from ExxonMobil Chemical Company. TABLE-US-00001 TABLE 1
Compositions of Invention and Comparative Examples Comparative
Examples Examples Commercial Oil A Oil B Oil C Oil D Oil E Oil F
Oil G MTO Reference Synthetic AGO Additives in Basestocks*, wt %
Extreme Pressure - High Presssure SIB 2.54 Extreme Pressure - High
Presssure SIB 1.14 3.43 2.28 0.548 Extreme Pressure - High
Presssure SIB 1.13 1.13 Antiwear - Mobilad C-421 - Acid Phosphate
0.238 0.738 1.476 0.703 0.690 0.112 0.818 Antiwear - Irgalube 349 -
Aryl Phosphate 0.047 0.095 Dispersants - TEPA Succinimide + 0.593
0.180 0.360 0.893 1.010 0.143 1.19 Borated Version Rust Inhibitor -
Primene 81R 0.147 0.672 0.492 0.88 0.427 0.141 0.506 Rust Inhibitor
- Mobilad C-603 0.021 0.042 (Oxazolidone) Cobratec TT100 (Triazole
Derivative) 0.0049 0.016 0.032 0.030 0.030 Alkylated
Dimercaptothiadiazole - 0.0318 0.090 0.180 0.0795 0.0865 0.0127
0.103 Mobilad C-610 Other Additives (defoamants, antioxidants,
balance balance balance balance balance balance balance etc.)
Percentages and Ratios (mass %) in Oil: % S 0.513 0.564 0.531 1.538
1.035 0.246 1.29 % S/% Triazole Derivative 104 36 17 51 35 N/A N/A
N/A N/A
[0080] The fluids in Table 1 were examined in the Eaton Copper
Corrosion Test (TEP-247), which is a severe seven day corrosion
test run at 150.degree. C. This test is part of Eaton's PS-164 rev
7 specification for extended drain transmission fluids. The
requirement is less than 5 mg of metal loss. The results for the
compositions tested are shown in Table 2. The commercial MTO
reference performs well in this test, but this is expected since
the additive system is not based on S, P chemistry. The synthetic
automotive gear oil, based on S, P chemistry, gives a result of 301
mg weight loss, which is more representative of S, P type chemistry
in commercially available products. The examples F and G are
further proof of the corrosion seen with S, P-based additive
systems.
[0081] However, when lubricant compositions are designed within the
scope of this invention, i.e. to include a triazole-containing
derivative and thiadiazole-containing derivative, the corrosion is
dramatically reduced to typically single digit amounts of metal
loss due to corrosion. TABLE-US-00002 TABLE 2 Eaton Copper
Corrosion Test (TEP 247) Weight Loss, mg* Examples A 1 B 3 D 10 E 8
Comparative F 181 G 100 Commercial MTO Reference 2 Synthetic AGO
301 *Requirement: 5 mg max
[0082] In Table 3, several of the lubricants in Table 1 were
further evaluated in a screener test for the Eaton FZG Micropitting
Test (TEP 272). The screener test (C-GF gear/8.3
ms.sup.-1/120.degree. C. controlled, splash lube) was developed to
measure the amount of micropitting that occurred over the gear
surface after load stages 7 (50 h), 8 (100 h), 9 (100 h) and 10 (50
h). This screener for the Eaton FZG Micropitting Test was run on
Oils A and C and the results are contrasted in Table 3 to the
reference MTO fluid. One sees that the compositions formulated
according to this invention result in far less micropitting and
wear on the gear surface relative to the MTO reference oil.
TABLE-US-00003 TABLE 3 Screener for Eaton FZG Micropitting Test %
Area Micropitted Wear, mg Examples A 42 57 C 17 35 Comparative
Commercial MTO Reference 56.5 410
[0083] In Table 4, the results for ASTM D 5182 are shown. This test
measures the scuffing load capacity of oils used to lubricate
hardened steel gears. It mainly assesses the resistance to scuffing
of mildly additized oils such as industrial gear oils, transmission
oils, and hydraulic fluids. This test has also been incorporated
into transmission specification requirements, but is likely to be
replaced by a more severe EP load carrying test, e.g. FZG A10
gear/16.6 ms.sup.-1 R/120.degree. C. Heretofore, as far as the
present inventors are aware, it has not been known how to achieve
the combination of high load-carrying coupled with the meeting
severe corrosion and micropitting requirements. Embodiments of the
present invention solve this problem. TABLE-US-00004 TABLE 4
Evaluation of Scuffing Load Capacity with ASTM D 5182 Fail Load
Stage* Examples A 12+ B 12+ D 12+ Comparative Commercial MTO
Reference 7, 8 *Requirement: 8 or better
[0084] One of the advantages of embodiments of the present
invention is the ability of S, P-based EP/antiwear agents to
provide for an increase in the EP properties, while at the same
time improving the micropitting and corrosion performance of the
fluid. Without wishing to be bound by theory, the present inventors
believe that the excellent performance seen in the extended Eaton
Copper Corrosion Test is attributable in large part to the synergy
obtained when both a triazole-containing derivative and a
thiadiazole-containing derivative are present. The present
inventors are unaware of other lubricant compositions containing S,
P-based EP/antiwear additives that are able to meet these new
requirements. The lubricant compositions of this invention also
performed well in a micropitting test, which has become a desired
feature of new transmission fluids.
[0085] The lubricant compositions of the present invention may be
utilized, for example, in automotive transmissions, industrial gear
boxes or in other applications where lubricants come into contact
with copper or copper-containing alloys.
[0086] 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.
[0087] All patents and patent applications, test procedures (such
as ASTM methods, UL 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.
[0088] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the invention
have been described with particularity, it will be understood that
various other modifications will be from the spirit and scope of
the invention. Accordingly, it is not intended that the scope of
the claims appended hereto be limited to the examples and
descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains. Preferred embodiments of the
invention include: (a) a lubricant composition suitable for use as
a lubricating oil, said composition comprising at least one
triazole-containing species and at least one thiadiazole-containing
species; which may be further limited by one or more of the
following limitations: said composition comprising at least one
triazole-containing species and at least one species from the group
consisting of dimercaptothiadiazole and alkylated derivatives
thereof; said composition wherein the triazole-containing species
is tolyltriazole; said composition further characterized by a ratio
of thiadiazole-containing species to triazole-containing species of
from about 20:1 to about 1:10, or more preferably about 10:1 to
about 1:1; said composition further comprising at least one
ingredient selected from (i) at least one sulfur-containing or
boron-containing extreme pressure agent; and (ii) at least one
phosphorus-containing antiwear agent; said composition further
characterized by having a ratio of sulfur to triazole-containing
species of less than about 150:1, or more preferably less than
about 100:1; or said composition further comprising ingredients
selected from extreme pressure agents, antiwear agents,
dispersants, detergents, rust inhibitors, corrosion inhibitors,
anti-foaming agents, demulsifiers, pour point depressants, seal
swell agents, emulsifiers, tackifiers, antioxidants, VI improvers,
thickening agents, and mixtures thereof; and (b) a lubricant
composition according to any permutation given or fairly suggested
by (a) and further comprising at least one basestock selected from
API Groups I-V; and (c) an automotive transmission oil, industrial
gear oil, hydraulic fluid, tractor oil comprising the lubricant
composition of given or fairly suggested by (a) or (b); and (d) a
manual transmission oil comprising and of the lubricant
compositions given or fairly suggested by (a) or (b), which may
also be further limited by embodiments wherein a basestock is
included, said basestock selected from API Groups I-V and
preferably selected from API Group IV, API Group V, and mixtures
thereof, and still more preferably wherein said basestock
composition is selected from API Group IV, and yet still more
preferably wherein said basestock composition comprises 2 cSt and
150 cSt PAO or 4 cSt PAO and 150 cSt PAO, or any of the
aforementioned compositions further comprising polyisobutylene; and
(e) a lubricating fluid comprising a corrosion inhibitor, the
improvement comprising the presence of an effective amount of a
combination of a triazole-containing species and a
thiadiazole-containing species (which embodiment may be further
limited by any of the composition limitations given or fairly
suggested by this paragraph); and (f) a vehicle comprising a manual
transmission, said manual transmission lubricated by a composition
according to any of the limitations given or fairly suggested by
this paragraph; and (g) a transmission lubricated by any one of the
compositions given or fairly suggested in this paragraph; and (h) a
transmission lubricated by the lubricating fluids given or
suggested in this paragraph; and (i) a method of preparing a
lubricating composition comprising combining any of the
compositions given or fairly suggested in (a) with at least one
basestock selected from API Group I-V; and (j) a method of
lubricating a transmission comprising adding any composition given
or fairly suggested in this paragraph a transmission; and (k) a
composition comprising at least one thiadiazole-containing species
and at least one triazole-containing species in the ratio of about
20:1 to about 1:10, more preferably 10:1 to about 1:1, either
compositions of which may further comprising at least one
ingredient selected from (i) at least one sulfur-containing or
boron-containing extreme pressure agent; and (ii) at least one
phosphorus-containing antiwear agent, and (1) a fully formulated
lubricant composition based on S, P chemistry comprising at least
one thiadiazole-containing species and at least one
triazole-containing species in the ratio of about 20:1 to about
1:10, preferably wherein said ratio is about 10:1 to about 1:1. As
mentioned, any of these would immediately suggest to one of
ordinary skill in the art in possession of the present disclosure
numerous modifications.
* * * * *