Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
VAPOR PHASE CORROSION INHIBITION
BACKGROUND OF THE INVENTION
[0001] The disclosed technology relates to the inhibition of corrosion
on electri-
cally conductive componentry subjected to an automotive lubricant composition,
but
that is not submersed in the lubricant composition, or in other words, vapor
phase cor-
rosion inhibition. The technology more particularly relates to the use of
azole com-
pounds capable of inhibiting corrosion of the electrically conductive
componentry in
the vapor space above an automotive lubricant composition, and often in the
liquid
phase of the lubricant composition as well.
[0002] Corrosion is of increasing relevance in the automotive industry
due to elec-
trification of vehicle drivelines, whether in full electric vehicles, hybrid
vehicles or
even internal combustion vehicles. Although transmission lubricating oils are
designed
to protect metal (most often copper or iron) surfaces submerged in the oil
from corro-
sion, some lubricants can be still be corrosive. Further, issues are arising
due to cor-
rosion of parts not submerged in the oil. For example, the evolution of
transmissions
is such that there are more sensors being used that are not immersed in the
lubricant
but are exposed in the vapor space to corrosive species. Since such
electronics are
typically not submerged in the lubricant, these electronics are not protected.
Corrosion
inhibitory performance for non-submerged electronics is not currently
encompassed
in vehicle lubricant specifications, but it is anticipated that vapor phase
corrosion
performance will become increasingly important, particularly with respect to
sensitive
electronics where even slight corrosion can interrupt the function of the
electronics.
Corrosion has been studied in the vapor phase, however the corrosion phenomena
that have thus far been described are primarily due to atmospheric corrosion
(e.g.
based on humidity, oxidation and salts), while the corrosion with respect to
electron-
ics in the headspace above an automotive lubricant will have significantly
different
set of environmental contributors (e.g., low humidity, low oxygen, volatile
lubricant
and lubricant degradation products).
[0003] A need exists to provide corrosion protection to electrically
conductive
componentry in automotive vehicles that are not submerged in a protective
lubricant
composition. That is, a need exists for vapor phase corrosion protection to
electrically
conductive componentry in vehicles.
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SUMMARY OF THE INVENTION
[0004] It has been found that certain azole compounds having
sufficiently high va-
por pressure to escape the liquid phase of a lubricant composition can provide
vapor
phase corrosion protection above the lubricant composition.
[0005] The disclosed technology, therefore, solves the problem of vapor
phase cor-
rosion of electrically conductive componentry in vehicles by providing a
lubricant
composition containing an azole compound capable of inhibiting corrosion of
the
electrically conductive componentry in the vapor space above the lubricant
compo-
sition and a method therewith.
[0006] The lubricant composition can include an oil of lubricating
viscosity and
an azole compound capable of escaping the lubricant composition and inhibiting
cor-
rosion in a vapor space above the lubricant composition.
[0007] In an embodiment, the azole compound can be a low molecular
weight
triazole or low molecular weight tetrazole compound. In some embodiments, the
azole compound can be an N-substituted azole compound that will decompose to a
low molecular weight triazole or low molecular weight tetrazole compound under
the
operating conditions of an automotive device. In further embodiments, the
azole
compound can be an N-substituted azole compound that will decompose in the
pres-
ence of a compound that reacts with the N-substituted azole compound resulting
in a
low molecular weight triazole or low molecular weight tetrazole compound.
[0008] The lubricant composition can further include a compound that
reacts with
the N-substituted azole compound resulting in a low molecular weight triazole
or low
molecular weight tetrazole compound.
[0009] In embodiments, the composition can further contain a volatile
compound
corrosive to electrically conducting componentry.
[0010] There is also provided a method of lubricating an automotive
device hav-
ing electrically conducting componentry. The method includes providing an auto-
motive device having electrically conducting componentry, some portion of said
componentry being dry, then delivering to the automotive device a lubricant
compo-
sition as set forth above, and operating the automotive device.
[0011] The electrically conducting componentry can include, for
example, elec-
trical wires, electrical sensors, printed circuit boards, or an electric
motor.
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[0012]
The electrically conducting componentry can, for example, contain copper
or a copper alloy.
[0013]
In embodiments, the method can be applied where the automotive device
contains a transmission, such as, for example, a dual clutch transmission, or
a trans-
mission that is driven by an electric motor.
[0014]
In further embodiments, the method can be applied where the automotive
device contains an axle. In some embodiments, the axle can be driven by an
electric
motor.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Various preferred features and embodiments will be described below
by way
of non-limiting illustration.
[0016]
One aspect of the technology encompasses a lubricant composition of 1) an
oil of lubricating viscosity, 2) an azole compound capable of inhibiting
corrosion of
electrically conductive componentry, both in the liquid phase of the lubricant
com-
position and in the vapor space above the lubricant composition, and 3) a
volatile
compound corrosive to the electrically conductive componentry.
Oil of Lubricating Viscosity
[0017]
One component of the disclosed technology is an oil of lubricating viscosity,
also referred to as a base oil. The base oil may be selected from any of the
base oils in
Groups I-V of the American Petroleum Institute (API) Base Oil
Interchangeability
Guidelines (2011), namely
Base Oil Category Sulfur (%) Saturates (%) Viscosity Index
Group I >0.03 and/or <90 80 to less than 120
Group II <0.03 and >90 80 to less than 120
Group III <0.03 and >90 >120
Group IV All polyalphaolefins (PA0s)
Group V All others not included in Groups I, II, III or IV
[0018]
Groups I, II and III are mineral oil base stocks. Other generally recognized
categories of base oils may be used, even if not officially identified by the
API: Group
II+, referring to materials of Group II having a viscosity index of 110-119
and lower
volatility than other Group II oils; and Group III+, referring to materials of
Group III
having a viscosity index greater than or equal to 130. The oil of lubricating
viscosity
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can include natural or synthetic oils and mixtures thereof. Mixtures of
mineral oil and
synthetic oils, e.g., polyalphaolefin oils and/or polyester oils, may be used.
[0019] In one embodiment the oil of lubricating viscosity has a
kinematic viscosity
at 100 C by ASTM D445 of 2 to 7.5 or 10, or 3 to 6, or 3.25 to 6, or 3.5 to 5
mm2/s,
or from 2 to 7 or 3 to 6 or 3 to 5. In one embodiment the oil of lubricating
viscosity
comprises a poly alpha olefin having a kinematic viscosity at 100 C by ASTM
D445
of 2 to 7.5 or any of the other aforementioned ranges.
Azole Compound
[0020] The lubricant composition also contains an azole compound
capable of in-
hibiting corrosion of electrically conductive componentry in the space above
the lub-
ricant composition.
[0021] The phrase "electrically conductive componentry" is used to
refer to com-
ponents in an automobile engine or driveline that conduct electricity, such
as, for
example, electrical wires, electrical sensors, printed circuit boards,
electric motors,
etc. Such components are generally kept "dry," meaning the components are not
submerged in a lubricant composition, but they will in many cases be in close
prox-
imity and exposed to a lubricant composition. Such electrically conducting
compo-
nentry can be prepared from copper or other electrically conductive material,
such
as, for example, copper alloys (brass, bronze), silver, aluminum, gold,
platinum, tin,
and alloys of any of the foregoing, or other like electrically conductive
materials.
[0022] Many azole compounds will exhibit corrosion inhibition in the
liquid
phase of a lubricant composition. However, not all azole compounds will
exhibit
corrosion inhibition in the vapor space above the lubricant composition. To
exhibit
such vapor phase corrosion inhibition, the azole compound first must have
suffi-
ciently high vapor pressure to vaporize, i.e., escape the liquid phase of the
lubricant
composition and enter the vapor phase. More than just escaping the liquid
phase, the
azole compound must also be capable of coating the electrically conductive
compo-
nentry to protect the componentry from other volatile compounds present in the
vapor
phase that would otherwise be corrosive to the electrically conductive
componentry.
[0023] While not wishing to be bound by theory, the coating of the
electrically
conductive componentry may arise when the azole compound includes more than 2
ring nitrogens, and has a proton available on the azole ring to interact with
the metal
of the electrically conductive componentry. Azole compounds capable of
inhibiting
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corrosion of the electrically conductive componentry in the vapor space above
a lub-
ricant composition thus can include low molecular weight triazoles and low
molecu-
lar weight tetrazoles. By low molecular weight, it is meant a compound having
a
molecular weight between about 50 and 350 daltons, or between about 55 and 250
5 daltons, or between about 60 and 150 or 200 daltons. Such compounds
include, for
example, those of formulas I or II:
/N
R2 H
N II
/N
ZN
H
where Ri and R2 can be, individually, H or a Ci to C9 alkyl group
[0024] Examples of azole compounds of formula I can include, for
example,
1,2,4-triazole, 3-methyl-1,2,4-triazole and the like. Examples of formula II
can in-
clude, for example, 1H-tetrazole, 5-methyltetrazole, and the like.
[0025] The azole compound capable of inhibiting corrosion of the
electrically
conductive componentry can also include N-substituted azole compounds. N-
substi-
tuted azole compounds may provide vapor phase corrosion protection on their
own,
or decompose to a low molecular weight triazole or low molecular weight
tetrazole
compound under an operating condition of the automotive device; or decompose
to a
low molecular weight triazole or low molecular weight tetrazole in the
presence of a
compound that reacts ("reactive compound") with the N-substituted azole
compound
resulting in the release or formation of a low molecular weight triazole or
low mo-
lecular weight tetrazole compound.
[0026] Formulas I and II may be reacted with an alkyl (meth)acrylate to
obtain a
compound having an alkyl (meth)acrylate substituent on a ring nitrogen. The
formu-
las may also be reacted to obtain a formula with an amine substituent on a
ring nitro-
gen, for example, by reacting with formaldehyde and the desired amine.
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[0027] An example N-substituted azole compound with an amine
substituent can
include 1,2,4 triazoles of formula III:
\R4
where R3 and R4 can be, independently Ci-C22, or C2-C20, or C3-C18, or C3 -C
16 or C12,
either linear or branched hydrocarbon groups, phenyl group, or two ends of a
hydro-
carbon chain forming a cyclic structure, or where at least one of R3 and R4
can be H.
[0028] In some embodiments, the N-substituted azole compound can be an
N-
branched substituted 1,2,4 triazole, such as those of formula III where R3 and
R4 can
be, independently Ci-C22, or C2-C20, or C3-C18, or C3-C16 or C12 branched
hydrocar-
bon groups, or two ends of a hydrocarbon chain forming a cyclic structure.
Example
structures of formula III can include:
N,NBis( I -methyl ethyl)- IH- 1,2,4-tri a - L
N
Zol e- I -lnethaliamine
N,N-diisobuty1-1H-1,2,4-triazole-1-
methanamine
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L N
N/
AT,N-dicyclohexyl- 1H- 1 ,2,4-tri azole- 1 -
methanamine
N_,
,,,,v_bis(2-ethy1hexyl)- 1H- 1,2,4-
Tri azol e- 1 -methanamine
1-((1 H-1,2,4 -tri azol - 1 -yl)methyl)pi peri -
dine
V,Nbis(tridecyl )- 1R- 1 ,2,4-Tri azole- 1 -
_.======N)
methanamine
*mixed branched isomers
N
C131127 v13H27
[0029] In some embodiments, the N-substituted azole compound can be an N-
linear substituted 1,2,4 triazole, such as those of formula III where R3 and
R4 can be,
independently linear Ci-C22, or C2-C20, or C3-C18, or C3-C16 or C12
hydrocarbon
groups (including carbonyl groups or acrylamide groups). Example structures of
for-
mula III can include:
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N-----\
__
N,N-dim ethyl- 1-( 1H- 1 ,2,4-triazol- 1- N , yl)methanamine
\
N-----N
LN/N
N,N-dibutyl- 1H- 1 ,2,4-triazole- 1 -meth- N
anamine
Y
N
N,N-dicoco- 1 -( 1H- 1 ,2,4-tri azol - 1 - -----1
N
yl)methanamine I
N
Coco Coco
[0030] In
other embodiments, the N-substituted azole compounds can include, for
example, N-single substituted 1,2,4 triazoles, such as those of formula III
where R3
and R4 can be, independently Ci-C22, or C2-C20, or C3-C18, or C3-C16 or C12,
either
linear or branched hydrocarbon groups, or two ends of a hydrocarbon chain
forming
a cyclic structure, and where at least one of R3 and R4 is H. Example
structures of
formula III can include:
N-(( 1H- 1 ,2,4-tri azol - 1 -yl)methyl)octan-
3-amine H
N \
L
[0031]
The azole compound can also include N-substituted 1,2,4 triazoles, where
the N-substitutent is at the 4 position, as in formula IV:
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N >Iv
L
\R4
where R3 and R4 are as defined above. Compounds of formula IV may, in some
embodiments, be naturally occurring impurities or minor isomers formed during
the
manufacture of compounds of formula III.
[0032] Other N-substituted azole compounds can include 1,2,3 triazoles
of for-
mula V:
N V
%N
R6
N
F(5
where R5, can be, independently Ci-C22, or C2-C20, or C3-C18, or C3-C16 or Cu,
either
linear or branched hydrocarbon groups, phenyl group, or two ends of a
hydrocarbon
chain forming a cyclic structure, R6 and R7 can be C1-C4, or C1-C3, or C1-C2,
or where
at least one of R5, R6 and R7 can be H, or where both R6 and R7 are H, or at
least one
of R5, R6 and R7 can include carbonyl or acrylamide groups, such as in methyl
pro-
pionate or ethylhexyl propionate and the like, which may be formed by
contacting the
azole compound with an acrylate, acrylic acid, acrylamide or combination
thereof.
[0033]
Further N-substituted azole compounds include tetrazoles of formula VI:
N/ y R8
vi
R9
1\ R9
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where R8 and R9 can be, independently Ci-C22, or C2-C20, or C3-C18, or C3-C16
or C12,
either linear or branched hydrocarbon groups, a phenyl group, or two ends of a
hy-
drocarbon chain forming a cyclic structure, or where at least one of R8 and R9
can be
5 H.
[0034] The azole compounds are formulated into a lubricant composition
at a
level sufficient to provide suitable corrosion protection in the vapor phase
when in
use. In general, levels of about 30 ppm to 5 wt% of the azole compound are
suitable
in most applications. In some embodiments, the azole compound can be
incorporated
10 at a level of about 50 ppm to 4wt%, or about 250ppm to 3wt%, based on
the total
weight of the lubricant composition, or even from 500ppm to 2wt% or 1000 ppm
to
1 wt%. In some embodiments, the azole compound can be incorporated at a level
of
from about 100 ppm to 5000 ppm, or 250 ppm to 2500 ppm, or 500 to 2000 ppm.
Azole Decomposition
[0035] The azole compounds above may decompose to provide a low molecular
weight azole compound. Decomposition can occur, for example, due to
temperatures
encountered during operation of the automotive device.
[0036] Decomposition can also occur due to the presence of a compound
("reac-
tive compound") that reacts with the N-substituted azole compound resulting in
re-
lease or formation of a low molecular weight triazole or low molecular weight
te-
trazole compound. Thus, the lubricant composition can include a compound that
reacts with the N-substituted azole compound resulting in decomposition to a
low
molecular weight triazole or low molecular weight tetrazole compound.
[0037] In some embodiments, the reactive compound may be an
electrophile, a
nucleophile, or a combination thereof. Thus, the lubricant composition can
also in-
clude a compound that is electrophilic to the azole compound and/or a
nucleophilic
to substituents on the azole compound, or a combination thereof.
[0038] Electrophilic compounds may include, for example, Lewis acids
and Bronsted
acids. Examples of electrophilic compounds can include, for example, hydrogen
(whether on its own or as an "onium" compound such as NH4 + or H30+); metal
cations
such as Li+, Cu(I/II), Ti(IV), Fe(II/III), etc.; trigonal planar species such
as BF3 and
the like; a,f3-unsaturated carbonyls; polar molecules like carbon dioxide,
etc. Such
compounds can arise in the lubricant from other additives in the lubricant,
such as,
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for example from detergent substrates and antiwear additives and their
decomposition
products.
[0039] Nucleophilic compounds can include Lewis bases. Examples of
nucleophiles
can include iodine, alcohols, such as, for example, methanol, ethanol or
higher alco-
hols, amines, such as ammonia, or an amine from the head group of a dispersant
or
surfactant. Here again, such compounds can arise in the lubricant from other
addi-
tives in the lubricant, such as, for example from friction modifiers and their
decom-
position products.
Liquid Phase Corrosion Inhibitor
[0040] The lubricant composition can also include corrosion inhibitors that
work in
the liquid to prevent corrosion in the liquid phase. An example of such a
liquid phase
corrosion inhibitor can include, for example, a substituted thiadiazole, such
as a dimer-
captothiadiazole (DMTD) derivative. DMTD derivatives may be used to impede cor-
rosion of copper. The dimercaptothiadiazole derivatives typically are soluble
forms
or derivatives of DMTD. Materials which can be starting materials for the
prepara-
tion of oil-soluble derivatives containing the dimercaptothiadiazole nucleus
can in-
clude 2,5-dimercapto-[1,3,4]-thiadiazole, 3,5-dimercapto-[1,2,4]-thiadiazole,
3,4-
dimercapto-[1,2,5]-thiadiazole, and 4,-5-dimercapto-[1,2,3]-thiadiazole. Of
these the
most readily available is 2,5-dimercapto-[1,3,4]-thiadiazole. Various 2,5-bis-
(hydro-
carbon dithio)-1,3,4-thiadiazoles and 2-hydrocarbyldithio-5-mercapto-[1,3,4]-
thiadi-
azoles may be used. The hydrocarbon group may be aliphatic or aromatic,
including
cyclic, alicyclic, aralkyl, aryl and alkaryl. Similarly, carboxylic esters of
DMTD are
known and may be used, as can condensation products of alpha-halogenated
aliphatic
monocarboxylic acids with DMTD or products obtained by reacting DMTD with an
aldehyde and a diaryl amine in molar proportions of from about 1:1:1 to about
1:4:4.
The DMTD materials may also be present as salts such as amine salts. In other
em-
bodiments, the DMTD compound may be the reaction product of an alkyl phenol
with
an aldehyde such as formaldehyde and a dimercaptothiadiazole. Another useful
DMTD derivative is obtained by reacting DMTD with an oil-soluble dispersant,
such
as a succinimide dispersant or a succinic ester dispersant.
[0041] The amount of the DMTD compound, if present, may be 0.01 to 5
percent
by weight of the composition, depending in part on the identity of the
particular com-
pound, e.g., 0.01 to 1 percent, or 0.02 to 0.4 or 0.03 to 0.1 percent by
weight. Alter-
natively, if the DMTD is reacted with a nitrogen-containing dispersant, the
total
weight of the combined product may be significantly higher in order to impart
the
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same active DMTD chemistry; for instance, 0.1 to 5 percent, or 0.2 to 2 or 0.3
to 1
or 0.4 to 0.6 percent by weight.
[0042] In some embodiments, the substituted thiadiazole can be present
in a for-
mulation that is substantially free or free of reactants that could react with
the substi-
tuted thiadiazole to form a volatile corrosive thiol, such as, for example, a
hydrogen
phosphite.
Volatile Corrosive Compound
[0043] The lubricant composition will, by virtue of the problem
statement, also
include a volatile compound that is corrosive to the electrically conducting
compo-
nentry, or "volatile corrosive compound" for short. Volatile, in reference to
the vol-
atile corrosive compound, has the same meaning as with the azole compound,
that is,
the volatile corrosive compound must have sufficiently high vapor pressure to
vapor-
ize, i.e., escape the liquid phase of the lubricant composition under
operating condi-
tions in an automobile and enter the vapor phase.
[0044] The volatile corrosive compound can be a compound added to the
lubricant
composition and intended for other bulk fluid purposes, such as, for example,
bulk
phase rust inhibition, friction modification, or wear and oxidation
prevention. The
volatile corrosive compound can also be generated in situ, for example, as a
natural
degradation product of the components of the lubricant composition, or from
the re-
action of two or more components in the lubricant composition.
[0045] In an embodiment, the volatile corrosive compound can be a
volatile sul-
fur-containing compound, such as a thiol. Other sulfur-containing compounds
that
can cause corrosion include, for example, sulfurized olefins, disulfides,
sulfurized es-
ters, mercaptans, thioethers, dialkyldithiophosphoric acids and their salts,
and dithio-
carbamates.
[0046] The volatile corrosive compound can also include hydrogen
sulfide arising
from the degradation or hydrolysis of any of the sulfur-containing compounds.
Like-
wise, the volatile corrosive compound can be a low molecular weight mercaptan
arising
from the degradation of sulfurized olefins, or a sulfur dioxide compound from
thermal
degradation of a sulfonate or sulfone. In an embodiment, the volatile
corrosive com-
pound can be the reaction product of a substituted thiadiazole and a hydrogen
phos-
phite.
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Methods of Vapor Phase Corrosion Inhibition
[0047] A further aspect of the present technology encompasses a method
of lubri-
cating an automotive device having electrically conducting componentry. The
method includes providing an automotive device comprising electrically
conducting
componentry with some portion of the electrically conducting componentry being
dry
(i.e., not submerged in a lubricant composition). A lubricant composition, as
dis-
closed above, can be delivered to the automotive device, and the automotive
device
is operated.
[0048] The automotive device is, in one embodiment, a driveline device.
The
driveline device can be, for example, a gear, an axle, a drive shaft, an
automatic or
manual transmission, or a driveline of an off-highway vehicle (such as a farm
tractor).
Such driveline devices are lubricated by gear oils, axle oils, drive shaft
oils, traction
oils, manual transmission oils, automatic transmission oils, or off highway
oils (such
as a farm tractor oil).
[0049] In one embodiment a method of lubricating a manual transmission that
may or may not contain a synchronizer system is provided. In one embodiment
there
is provided a method of lubricating an automatic transmission. In one
embodiment
the invention provides a method of lubricating an axle.
[0050] Automatic transmissions that may be encompassed by the disclosed
method include, for example, continuously variable transmissions (CVT),
infinitely
variable transmissions (IVT), toroidal transmissions, continuously slipping
torque
converter clutches (CSTCC), stepped automatic transmissions or dual clutch
trans-
missions (DCT).
[0051] The automatic transmissions can contain continuously slipping
torque con-
verter clutches (CSTCC), wet start and shifting clutches and in some cases may
also
include metal or composite synchronizers. Dual clutch transmissions or
automatic
transmissions may also incorporate electric motor units.
[0052] With respect to axles and gears, the method can include
employing a gear
oil or axle oil in a planetary hub reduction axle, a mechanical steering and
transfer
gear box in utility vehicles, a synchromesh gear box, a power take-off gear, a
limited
slip axle, and a planetary hub reduction gear box. Axles may also incorporate
electric
motors units. Motors may be placed, for example, "in-wheel" or on the front or
rear
axle. The electric motor may also be incorporated into the driveshaft.
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[0053] The amount of each chemical component described is presented
exclusive
of any solvent or diluent oil, which may be customarily present in the
commercial ma-
terial, that is, on an active chemical basis, unless otherwise indicated.
However, unless
otherwise indicated, each chemical or composition referred to herein should be
inter-
preted as being a commercial grade material which may contain the isomers, by-
prod-
ucts, derivatives, and other such materials which are normally understood to
be present
in the commercial grade.
[0054] It is known that some of the materials described above may
interact in the
final formulation, so that the components of the final formulation may be
different
from those that are initially added. For instance, metal ions (of, e.g., a
detergent) can
migrate to other acidic or anionic sites of other molecules. The products
formed
thereby, including the products formed upon employing the composition of the
present
invention in its intended use, may not be predisposed to easy description.
Nevertheless,
all such modifications and reaction products are included within the scope of
the pre-
sent invention; the present invention encompasses the composition prepared by
admix-
ing the components described above.
[0055] As used herein, the term "about" means that a value of a given
quantity is
within 20% of the stated value. In other embodiments, the value is within
15% of
the stated value. In other embodiments, the value is within 10% of the stated
value. In other embodiments, the value is within 5% of the stated value. In
other
embodiments, the value is within 2.5% of the stated value. In other
embodiments,
the value is within 1% of the stated value.
[0056] The invention herein is useful for inhibiting corrosion of non-
submerged
electrically conductive componentry in lubricated driveline devices, which may
be bet-
ter understood with reference to the following examples.
EXAMPLES
[0057] Sample Preparation - General Procedure for coupling azoles to
alkyla-
mines with paraformaldehyde: 1.0 mole of azole is combined with 1.0 mole of
alkyl-
or dialkylamine and the mixture is heated to 60-80 C with agitation.
Paraformalde-
hyde, from 0.94 to 1.0 equivalent, is then added. For low mw amines, the
paraform-
aldehyde charge is divided into two equal portions, and the second portion is
not
charged until the reaction exotherm from the 1st charge has subsided. The
equivalent
weight of the paraformaldehyde is calculated as follows:
Eq wt = 30.0264/(wt% CH2=0 in paraformaldehyde)
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Once the exotherm from the paraformaldehyde addition has subsided, heating is
con-
tinued until all solids have dissolved. Vacuum is then applied to the reaction
mixture
to remove the by-product water generated by the reaction. No further
purification of
the product is necessary. Samples prepared by this method are provided below.
5 [0058] Sample 1: A commercial sample of 1,2,4-triazole was obtained
from To-
kyo Chemical Industry Company. Ltd.
[0059] Sample 2: 1,2,4-Triazole (0.81 mole) was reacted with piperidine
(0.81
mole) and 91% paraformaldehyde (0.761 equivalent) per the general procedure to
yield 131.66 g (98% yield) of clear, slightly yellow liquid that froze upon
cooling.
10 The product, 1-((1H-1,2,4-triazol-1-yl)methyl)piperidine, had a melting
point of 61-
63 C. 41 and 13C NMR of the product showed that it was exceptionally pure.
[0060] Sample 3: 1,2,4-Triazole (0.746 mole) was reacted with
diisopropylamine
(0.738 mole) and 91% paraformaldehyde (0.701 equivalent) per the general proce-
dure to yield 105.13 g (77% yield) of clear, faintly yellow liquid. 111 and 1-
3C NMR
15 of the product showed that it was impure. Primary impurities were
unreacted 1,2,4-
triazole and di(1H-1,2,4-triazol-1-yl)methane, the product of two moles of
triazole
coupling with formaldehyde.
[0061] Sample 4: 1,2,4-Triazole (0.653 mole) was reacted with
dibutylamine
(0.654 mole) and 91% paraformaldehyde (0.614 equivalent) per the general proce-
.. dure to yield 131.64 g (96% yield) of clear, colorless liquid. The product,
N,N-dibu-
ty1-1H-1,2,4-triazole-1-methanamine, was substantially pure by 41 and 13C NMR.
[0062] Sample 5: 1,2,4-Triazole (0.654 mole) was reacted with
diisobutylamine
(0.654 mole) and 91% paraformaldehyde (0.615 equivalent) per the general proce-
dure to yield 131.68 g (96% yield) of a colorless, low-melting, crystalline
solid, N,N-
diisobuty1-1H-1,2,4-triazole-1-methanamine, having a melting point of < 45 C.
The
product was substantially pure by 1E1 and 13C NMR, the only impurity being a
trace
of the triazole-to-triazole coupled compound.
[0063] Sample 6: 1,2,4-Triazole (0.653 mole) was reacted with 2-
ethylhexyla-
mine (0.654 mole) and 91% paraformaldehyde (0.615 equivalent) per the general
procedure to yield 131.48 g (96% yield) of clear, almost colorless liquid. The
41 and
13C NMR spectra showed, however, that the desired product, N4(1H-1,2,4-triazol-
1-
yl)methyl)-2-ethylhexan-1-amine was not obtained in high purity. The NMR
spectra
indicate that the product obtained contained a mixture of at least three
compounds in
addition to the desired compound.
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[0064] Sample 7: 1,2,4-Triazole (0.534 mole) was reacted with
dicyclohexyla-
mine (0.533 mole) and 91% paraformaldehyde (0.501 equivalent) per the general
procedure to yield 139.07 g (99.5% yield) of a nearly colorless, crystalline
solid,
N,N-dicyclohexy1-11-1-1,2,4-triazole-1-inethanamine, having a melting point of
> 65
C. The product showed good purity by 41 and 13C NMR, the only impurities being
trace amounts of the triazole-to-triazole coupled compound and unreacted
triazole.
[0065] Sample 8a: The commercial corrosion inhibitor Irgamet 30 from
BASF
Corporation, CAS Number 91273-04-0, is the formaldehyde-coupled product of
1,2,4-triazole with bis(2-ethyhexyl)amine. 41 and 13C NMR spectra of this
sample
show that it is very pure.
[0066] Sample 8b: The general procedure was used to prepare a product
analo-
gous to Irgamet 30. 1,2,4-Triazole (0.439 mole) was reacted with bis(2-eth-
yhexyl)amine (0.440 mole) and 91% paraformaldehyde (0.411 equivalent) to give
142.71 g (100%) of clear, colorless liquid product. The 1H and 13C NMR spectra
of
this material showed that the purity was comparable to the commercial product
of
Sample 8a.
[0067] Sample 9: 1,2,4-Triazole (0.404 mole) was reacted with
oleylamine
(0.404 mole) and 91% paraformaldehyde (0.403 equivalent) per the general proce-
dure to yield 141.79 g (99.8% yield) of waxy product. The 111 and 1-3C NMR
spectra
showed that the product was a mixture of several compounds.
[0068] Sample 10: 1,2,4-Triazole (0.313 mole) was reacted with
ditridecylamine
(0.312 mole) and 95% paraformaldehyde (0.313 equivalent) per the general proce-
dure to yield 144.26 g (100% yield) of clear, nearly colorless liquid product.
The
ditridecylamine used in this Sample was obtained from BASF; it is a complex
mixture
of isomers. The 111 and 13C NMR spectra confirm that the product is a complex
mixture.
[0069] Sample 11: 1,2,4-Triazole (0.315 mole) was reacted with
dicocoamine
(0.316 mole) and 95% paraformaldehyde (0.314 equivalent) per the general proce-
dure to yield 142.15 g (98.9% yield) of clear, pale amber liquid product. The
alkyl
groups on the dicocoamine are primarily a mixture of saturated C12-C14 linear
hydro-
carbon chains. The 1E1 and 13C NMR show that the product is very pure.
[0070] Sample 12: A commercial sample of 5-Methyltetrazole was obtained
from
Tokyo Chemical Industry Company. Ltd.
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[0071] Sample 13: Using the general procedure, 5-methyltetrazole (0.490
mole)
and bis(2-ethylhexyl)amine (0.494 mole) were coupled with 91% paraformaldehyde
(0.458 mole) to give 165.75 g (99.4%) of clear, almost colorless liquid
product. The
11-1NMR spectrum shows that the product is very pure. Due to the lack of
hydrogen
atoms directly on the azole ring, however, it was not possible to say
conclusively
whether the formaldehyde-coupled substituent was attached to Ni or N2 of the
ring.
The NMR showed a single ring methyl group, though, indicating that only one of
the
two possible substitution isomers had formed.
[0072] Sample 14: 5-Phenyltetrazole (0.358 mole) and bis(2-
ethylhexyl)amine
(0.359 mole) were coupled with 91% paraformaldehyde (0.336 mole) using the gen-
eral procedure to give 142.81 g (99.2%) of clear, almost colorless liquid
product.
The 11-1NMR spectrum shows that the product is very pure. The position of the
for-
maldehyde-coupled substituent on the ring is not definitive, however a single
posi-
tional isomer is observed in the spectrum.
[0073] Sample 15: A commercial sample of 1,2-Dimethylimidazole was obtained
from Alfa Aesar.
[0074] Sample 16: A commercial sample of 2,4-Dimethylimidazole was
obtained
from Alfa Aesar.
[0075] Sample 17: A commercial sample of 1-Butylimidazole was obtained
from
Alfa Aesar.
[0076] Sample 18: A commercial sample of 1-Methyl-1,2,4-triazole was ob-
tained from Alfa Aesar.
[0077] Sample 19: A commercial oil-soluble corrosion inhibitor,
Skosanor KSP-
93, was obtained from Lubrizol Corporation. This product is the reaction
product of
tolyltriazole, bis(2-ethylhexyl)amine, and paraformaldehyde as shown below.
H3C
141 Ns:N
/\/))
[0078] Formulation A for testing vapor phase corrosion: The formulation
shown below, which is representative of a typical automotive transmission
fluid,
causes severe vapor-space corrosion of copper within a few days at 65 C,
despite
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having two known copper corrosion inhibitors (indicated by the asterisks "*").
In
some tests described below, Formulation A without the tolyltriazole is used.
Formulation A
Ingredient Generic Name wt%
3 cSt Group III oil 60.61
4 cSt 100N Group Ill oil 21.90
Viscosity modifier 10.96
Dispersant 3.00
Friction modifier 1.40
Antioxidant 0.60
Substituted thiadiazole * 0.50
Seal swell agent 0.35
Antiwear agent (phosphite based) 0.22
Detergent 0.12
Pour Point depressant 0.09
Ethoxylated amine 0.10
Mineral acid 0.10
Tolyltriazole * 0.03
Foam inhibitor 0.02
[0079] Semi-submerged Test: Formulation A is top-treated with the
Sample va-
por phase corrosion inhibitors listed above at the reported treat rates.
Freshly sanded
copper strips are half immersed in the top-treated fluids in 4-oz jars which
are capped
and placed in a controlled temperature oven. Corrosion of both the liquid-
immersed
portion and vapor-space portion of the coupons is assessed per the ASTM D130
rating
scale after a specified period. A blank (Formulation A with no top treat) is
used as a
standard in each test.
[0080] Example 1: Several Sample corrosion inhibitors were incorporated at
a
level of 500 ppm into Formulation A without tolyltriazole (listed as
"Baseline" in
Table 1). A semi-submerged test was conducted on each of these fluids at 65 C
for
seven days. ASTM D130 ratings for both the liquid and vapor space portions of
each
coupon are shown in table 1 below.
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Table 1
$ni pieEVapor imiLiquidm mlitopormLiqwd
Baseline 4C 1A 4C 1A
1 1A 1A 1A 1A
2 1A 1A 1A 1A
4 1A 1A 1A 1A
1A 1A 1A 1A
7 1A 1A 1A 1A
1A 1A 1A 1A
11 1A 1A 1A 1A
13 2A 1A 2A 1A
14 4C 1A 4C 1A
[0081] Example 2: The performance of three sample corrosion inhibitors
in a
5 semi-submerged test as a function of treat level in Formulation A without
tolyltria-
zole are shown in Table 2. The semi-submerged test was carried out at 80 C for
seven days. ASTM D130 ratings for both the liquid and vapor space (front side
only)
are listed.
Table 2
Top Treat Vapor Liquid Vapor Liquid Vapor Liquid
0 ppm 4C 1A 4C 1A 4C 1A
500 ppm 1A 1A 1A 1A 4C 1A
250 ppm 1A 1A 1A 1A 4C 1A
125 ppm 1A 1A 1A 1A 4C 1A
10 62.5 ppm 1A 1A 1A 1A 4C 1A
[0082] Example 3: Performance of the sample corrosion inhibitors was
demon-
strated in both low and high viscosity fluids. All three formulations
contained the
same performance additives as Formulation A, with the exception of the base
oil and
viscosity modifier. The base oil in Example 3a was a 2cSt polyalpha olefin,
the base
oil in Example 3b was a low viscosity petroleum alkylate and the base oil in
Example
3c was an 8cSt polyalpha olefin. None of these formulations contained a
polymeric
viscosity modifier.
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Table 3
Emoominixiompicakizt otiftwoommq
Back Front
Vapor Liquid Vapor Liquid
none 4C 1B 4C 1B
500 ppm 1A 1A 1A 1A
100 ppm 1A 1B 1A 1B
50 ppm 1A 1B 1A 1B
none 4C 1B 4C 1B
500ppm 1A 1A 1A 1A
simmignisminizxtmorcamiiwyo$tiimoionimisignisinisi
Back Front
none 4C 1B 4C 1B
500ppm 1A 1A 1A 1A
[0083] Example 4: Performance of the sample corrosion inhibitors was
also
5 demonstrated in an alternate fluid. Formulation B is a gear oil
formulation that con-
tains the additives listed below.
Formulation B
Lubicant Oil 96.42
Extreme pressure agent 2.9
Pour point depressant 0.3
Rust inhibitor 0.2
Corrosion inhibitor 0.1
Friction modifier 0.05
Antifoam 0.03
[0084] Formulation B was top treated with 500ppm of Sample 8a in one
instance
10 and 500ppm of Sample 19 in another instance. These top treated gear oil
formulations
were subjected to the semi-submerged test at 80 C for seven days. Results are
listed
in Table 4.
Table 4
Sample Vapor Liquid Vapor Liquid
None (blank) 3B 3B 3B 3B
Sample 8 1A 1A 1A 1A
15 Sample 19 3A 3A 2E 2E
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[0085] Example 5: This semi-submerged test is a short-duration
comparison of
several low molecular weight azoles in the Formulation A without
tolyltriazole. The
test was run at 80 C for 24 hours. Each Sample was added to Formulation A as a
top
treat at 1000ppm.
Table 5
pSamptem miNaporisii mbqtadm
1 1A 1A
12 1A 1A
4A 1B
16 4A 4A
17* 4A 1A
18 4A 1B
* Used Formulation A with tolyltriazole
[0086] Example 6: A 4-oz uncapped jar of the Formulation A was placed
inside
10 a 1/2-gallon wide-mouth jar. A freshly polished copper coupon was laid
across the top
of the small jar such that it was not in contact with the liquid. The outer
large jar was
capped and the entire assembly placed in an 80 C oven for two days. The
coupon
turned black (4C rating). This test proves that the corrosive species from the
Formu-
lation A is acting through volatilization of the corrosive species into the
vapor space
15 rather than through a mechanism whereby the corrosive species climbs up
the surface
of the coupon from the liquid phase.
[0087] Example 7: Two 4-oz uncapped jars of Formulation A, one top-
treated
with 1000 ppm of Sample 8 were placed inside of a 1/2-gallon wide-mouth jar. A
freshly polished copper coupon was laid across the top of the small jars such
that it
was not in contact with the liquids. The outer large jar was capped and the
entire
assembly placed in an 80 C oven for two days. The coupon remained in pristine
condition (1A rating). This test, in conjunction with Example 6 proves that
the vapor-
space inhibiting species from the top-treated Formulation A is acting through
volati-
lization into the vapor space rather than through a mechanism whereby the
inhibiting
species climbs up the surface of the coupon from the liquid phase. This test
also rules
out a mechanism whereby the corrosion inhibiting species reacts with or
neutralizes
the corrosive species in the liquid phase before it can volatilize.
[0088] Example 8: One 4-oz uncapped jar of Formulation A, and a second
4-oz
uncapped jar of 4 cSt Group III oil top-treated with 1000 ppm of Sample 8 were
placed inside of a 1/2-gallon wide-mouth jar. Anhydrous calcium sulfate
pellets were
also scattered on the bottom of the 1/2-gallon jar to maintain an anhydrous
environ-
ment inside the jar. A freshly polished copper coupon was laid across the top
of the
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small jars such that it was not in contact with the liquids. The outer large
jar was
purged with nitrogen, then capped and the entire assembly placed in an 80 C
oven
for 6 days. The coupon slowly turned black (4 rating). This test, in
conjunction with
Examples 6 and 7 proves that Sample 8 is not inherently capable of providing
vapor-
space corrosion inhibition.
[0089] Example 9: Performance of the sample corrosion inhibitors was
also
demonstrated in an alternate fluid. Formulation C represents a baseline manual
trans-
mission fluid.
Formulation C
Ingredient generic name Wt %
Base oil Balance to
100
Viscosity modifier (PMA Type) 7.58
Antioxidant (aminic) 0.3
Detergent (580 TBN calcium sul-
0.58
fonate)
Dispersant (PIB succinimide type) 1.7
Extreme pressure agent (sulfu-
0.3
rized olefin)
Antiwear agent (phos containing,
0.91
non-phosphite type)
Foam inhibitor 300ppm
[0090] Fluids E to K were generated by adding a thiadiazole corrosion
inhibitor
and/or inventive Sample 8b to Formulation C. Each fluid was tested & rated in
ac-
cordance with ASTM D130 at 121 & 150 C for 3 hours as well as being subjected
to
the semi-submerged test at 80 C for 168 hours. The results are given below:
Thiadiazole corrosion
inhibitor (wt%) 0 0.3 0 0 0 0.3 0.3 0.3
Inventive inhibitor 8b
(13Pm) 0 0 250 500 1000 250 500 1000
ASTM D130 at 121C 3B 1A 2D 2D 1B 1A 1A 1A
ASTM D130 at 150C 4A 1B 3B 3B 3B 1A 1A 1A
Semi submerged test
Liquid 3B 1B 3B 3B 1A 1A 1A 1A
Vapor 4C 4A 3B 2C 2C 1A 1A 1A
[0091] Each of the documents referred to above is incorporated herein by
reference,
including any prior applications, whether or not specifically listed above,
from which
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priority is claimed. The mention of any document is not an admission that such
docu-
ment qualifies as prior art or constitutes the general knowledge of the
skilled person in
any jurisdiction. Except in the Examples, or where otherwise explicitly
indicated, all
numerical quantities in this description specifying amounts of materials,
reaction con-
ditions, molecular weights, number of carbon atoms, and the like, are to be
understood
as modified by the word "about." It is to be understood that the upper and
lower
amount, range, and ratio limits set forth herein may be independently
combined. Sim-
ilarly, the ranges and amounts for each element of the invention can be used
together
with ranges or amounts for any of the other elements.
[0092] As used herein, the transitional term "comprising," which is
synonymous
with "including," "containing," or "characterized by," is inclusive or open-
ended and
does not exclude additional, un-recited elements or method steps. However, in
each
recitation of "comprising" herein, it is intended that the term also
encompass, as alter-
native embodiments, the phrases "consisting essentially of" and "consisting
of," where
"consisting of" excludes any element or step not specified and "consisting
essentially
of' permits the inclusion of additional un-recited elements or steps that do
not materi-
ally affect the essential or basic and novel characteristics of the
composition or method
under consideration.
[0093] While certain representative embodiments and details have been
shown for
the purpose of illustrating the subject invention, it will be apparent to
those skilled
in this art that various changes and modifications can be made therein without
de-
parting from the scope of the subject invention. In this regard, the scope of
the in-
vention is to be limited only by the following claims.
