Note: Descriptions are shown in the official language in which they were submitted.
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F-0152 ~UBRICANT COMPOSITIONS CONTAINING ANTIOXIDANT
MIXTURES OF THIAzoLEs AND THIADIAZOLE~
The invention relates to lubricant co~lpositions
which are normally susceptible to oxidative deterioration.
Triazoles have been employed in lubricant
compositions as metal deactivators. For example U.~.
Patent No. 3,597,353 discloses the use of
tetxahydrobenzotxiazole as a metal deactivating additive for
natural and synthetic lubricants. Similarly, U.S. Patent
No. 3,413,227 describes the use of C2-C20 alkyl-substituted
benzotriazole as corxosion or tarnish inhibitors. U.S.
Patent No. 4,060,491 discloses the use of 5-alkyl
benzotriazoles, for reducing wear between moving
steel-on-steel surfaces.
Reaction products of benzotriazoles are also
known. For example, U.S. Patent No. 3,788,993 describes the
reaction of benzotriazoles with alkyl or alkenyl succinic
anhydrides to form pxoducts which impart corrosion
inhibiting properties to lubricating oils.
U.~. Patent No. 4,048,082, discloses the use of
esters of adducts of benzotriazole and unsaturated
dicarboxylic acids or anhydrides for imparting antirust
properties to organic compositions.
~Je now found that combinations of benzotriazole
adducts with certain thiadiazoles have extremely valuable
properties. In particular, they confer good antioxidation
and corrosion-resistant properties on lubricating oils.
In accordance with the present invention, we t
therefore provide a lubricating composition containing a
major amount of a lubricant and an antioxidant amount of a
mixture of (1) an adduct of a benzotriazole compound and a
vinyl ether or a vinyl ester of a carboxylic acid and (2) an
alkyl dimercapto thiadiazole.
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1:~52975
F-0152 The benzotriazole adducts used in the mixtures of the present invention are formed by reacting a benzotxiazole
compound with a vinyl ether or a vinyl ester of a carboxylic
acid. They are described in our pending European Patent
Application No. 79301128 (Publn. No. 6710).
The benzotriazole compounds which may be used to
form the adducts have the formula:
R ~ Q
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N
H
where R is hydrogen or a hydrocarbyl group CDntaining from 1 to 12
carbon atoms, and preferably is hydrogen or an alkyl group
containing from 1 to 8 carbon atoms. Particularly preferred
are benzotriazole and ~uotriazole.
The vinyl ethers and vinyl esters which may be
utilized in forming the adducts of the present invention
have the formulae:
O
R'CH=C~aOR" and R'CH=CHOC-R"'
respectively, where R' is hydrogen or an alkyl group
containing from 1 to 8 carbon atoms in any isomeric
arrangement, R" is an alkyl group containing from 1 to 18
carbon atoms in any isomeric arrangement, and R"' may be the
same as R" or may be an aryl group, an alkaryl group or an
aralkyl group containing from 1 to 18 carbon atoms.
Preferred are those vinyl ethers and vinyl esters
wherein R' is hydrogen or an alkyl group containing from 1
to 11 carbon atoms, R" is an alkyl group containing from 1
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F-0152 to 8 carbon atoms, and R"' is an alkyl, axalkyl or alkaryl
group containing from about 1 to l4 caxbon ato~s.
Particularly preferred are those vinyl ethers and
vinyl esters wherein K' is hydrogen or alkyl of l to 2
carbon ato~s, R" is an alkyl group containing fxom l to 4
carbon atoms, and ~"' is an alkyl ox aryl gxoup containing
from l to 6 carbon atoms.
The benzotriazole adducts are foxmed by reacting
the benzotriazole compound with the vinyl ether or vinyl
ester of a carboxylic acid in proportions, expressed as
molar ratios of benzotriazole compound to vinyl ether or
vinyl carboxylate, fxom 1:1 to 1:lO, with from l:l to 1:l.5-
being preferred.
Temperatures from 25C to 150C, preferably from
80C to l20C are used. In general, the xeactants axe
contacted for l to 8 hours, preferably 2 to 4 hours. The
particular reaction times used will depend on the
temperature and the reactants employed and at higher
temperatuxes, the reaction time may be shorter than the time
at lower temperatures, for a given pair of reactants.
The reaction often proceeds without the presence
of any catalyst. However, catalysts of an acidic natuxe,
such as acetic acid, propionic acid, toluenesulfonic acid,
phosphonic or polyphosphonic and methanesulfonic acids may
be employed. Basic catalysts can also be used. Typical
examples include sodium or potassium alkoxides, sodium or
potassium metal and their hydxoxides.
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F-015~ The benzotriazole products of the present
invention may comprise severa~ isomers, i.e., the vinyl
ethers and vinyl esters may connect to the benzotriazole in
either the l-H or 2-H position. Also, both Markownikow and
anti-Markownikow additions may occur. It has been found
that each isomer is individually effective in imparting the
improved antioxidant and anti-corrosion properties to the
lubricant compositions. Accoxdingly, as used herein the
term "adducts" or "benzotriazole products(s)" may refer to
" any of the isomers produced, or the mixture of isomers.
The thiadiazoles used in the compositions are the
alkyl dimercapto thiadiazoles. The preferred thiadiazoles
are the 2,5-dimercapto-1,3,4- thiadiazoles of the formula:
~l - N
C~s/
where X4 and ~5 axe hydrocarbyl groups, either the same or
different, containing from 1 to 30 carbon atoms and x is 0
to 8. ~4 and R5 can be, for example, alkyl, aryl, alkaryl
o ox axalkyl, prefexably alkyl, and specific examples of which
are methyl, butyl, octyl, decyl, dodecyl, octadecyl, phenyl,
tolyl, benzyl, and the like. They can be made in accordance
with the method descxibed in U.S.Patent 2,719,125 and are
commercially available.
The present invention provides improved resistance
to oxidation of lubricating media including liquid oils of
lubxicating viscosity or gxeases. ~oth mineral (paraffinic
or naphthenic) and synthetic oils as well as mixtures of
them may be employed as the lubricant or the grease vehicle.
A wide variety of materials may be employed as thickening or
gelling agents for greases. These may include the
conventional metal salts or soaps and other thickening
agents such as the non-soap thickeners, for example, the
suxface-modified clays and silicas, axyl ureas and calcium
complexes.
Typical synthetic vehicles include polyolefins,polyglycols
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F-0152 and esters such as the polybutenes, hydrogenated
polydecenes, polypropylene glycol, polyethylene glycol,
trimethylol propane esters, neopentyl and pentaerythritol
esters, di(2-ethylhexyl) sebacate and di(2-ethylllexyl)
adipate.
The antioxidant mixtures of the present invention
are unexpectedly effective in mineral oils with a high
sulfur content.
The lubricants can also contain other materials,
for example, corrosion inhibitors, extreme pressure agents,
viscosity index improvers, co-antioxidants and anti-wear
agents.
The mixtures of the present invention may be
employed in any amount which is effective for imparting the
desired degree of oxidation improvement. The mixture is
effectively employed in amounts from 0.00l% to 0.~% by
weight, ~nd pxeferably from 0.0l% to 0.l% of the total
weight of the compoqitlon. When preparing the mixture of
the two compounds, from 20% to 80%, preferably 50% to 70% of
the benzotriazole adduct and from 80% to 20%, preferably
from 30% to 50% of the thiadiazole are used. All
percentages are by weight of total mixture.
The following examples will provide specific
illustrations of the invention described hereinabove.
EXAMPLE 1
dducts of Benzotriazole nd'n-Butyl'Vinyl Ether
A mixture of 59.5 g. of benzotriazole, 100 g. of
n-butyl vinyl ethe'r and 100 ml. of benzene was heated at
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F-0152 90C (refluxing) for 6 hr. An additional 50 g. of n-butyl
vinyl ether was added and refluxing at 90C was continued
for about 5 hours after which unreacted n-butyl vinyl ether
and the benzene solvent were removed by distillation. 'rO
the residue, petroleum ether (bp 30-60C) was added and
precipitated unreacted benzotriazole (9.1 g,) was removed by
filtering. Distillation of solvent from the filtrate left
90 g. (97%) of the mixed isomeric addition product.
Gas chromatography showed that the reaction
l0 product consisted of two major components (isomers) which
could not be separated by distillation. A narrow fraction,
having a bp of 100-103C at less than 0.1 mm. H~. was
estimated, from gas chromatography, to be a 30:70 mixture of
isomeric mono-addition products.
Elemental analysis conformed to a mono-adduct
reaction product having the empirical formula C12H17N3O:
Analysis (wt, ) C H N
Calculated for C12H17N3O : 65.73 7.81 19.16
Found : 66.34 7.63 19.9
One isomer (designated Isomer A) was separated by
elution from a column packed with"Alcoa F-20"alumina (Alcoa
is a trade mark), using petroleum ethex (bp 30-60C) as a
solvent. A satisfactory elemental analysis for the
mono-adduct was obtained:
Analysis for Isomer A (wt. %) C H N
Calculated for C12H17N3O : 65.73 7.81 19.16
Found : 66.31 8.08 19.0
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F-0152 The ultra-violet spectxum of Isomer A showed
maxima at 284.2, 277.6, 272.5 and a shoulder of 266.0 nm .
The ultra-violet spectrum for the starting benzotriazole was
significantly different, having maxima at 276, 259 and 254
nm. The nmr proton spectrum had a quartet, indicating
splitting of the proton by an adjacent methyl group showing
that the isomer is a Markownikow adduct. Based on these
data, it is concluded that Isomer A has the following
structure: ¦
!
N CH3
N CH
N OC4Hg
,
The second isomer (designated isomer B) was
isolated by benzene elution from a neutral alumina column.
A satisfactory elemental analysis for the mono adduct was
also obtained:
Analysis for Isomer B (wt. %) C H N
Calculated for C12H12N3O : 65.73 7.81 19.16
Found : 65.607.78 19.4
The ultra-violet spectrum of Isomer B showed maxima at 282,
261, and 254.5 nm. This is similar to the ultra-violet
spectrum of the starting benzotriazole which showed maxima
at 276, 259, and 254 nm. The infrared spectrum of Isomer B
showed significant differences from that of Isomer A. The
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F-0152 nmr proton spectrum ofIsomer B also had a quartet,
indicating that a methyl group is splitting a single
adjacent proton and this isomer is also a Markownikow adduct,
Based on these data, it is concluded that Isomer B has the
following stxucture:
CH3-C-OC4H9
H
EXAMPLE 2
'
Toluotriazole and n-Butyl Vinyl Ether Addition Product
A mixture of l90 g. of toluotriazole (5-methyl-
benzot~iazole), 300 g. of _-butyl vinyl ether and 200 ml. of
benzene was heated, while refluxing at 88-92C, for a total
of 14 hrs. Unreacted n-butyl vinyl ether and benzene
solvent were removed by distillation under reduced pressure
and the residue was cooled and filtexed through a bed of
Super Cel (trade mark) filter media. There was obtained 306
g. of the addition product, a clean dark amber liquid
~e~resenting a yleld of 92%.
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F-0152 EXAMPLE 3
Benzotriazole and Vinyl Acetate Addition Product - Base
Catalyzed
To benzotriazole ~59.5 g.) and potassium
tert-butoxide in toluene (lO0 ml.), heated at l03-ll5C,
vinyl acetate (86 g.) was added during about 2.25 hr. The
reaction mixture was then heated at 98C while stirring for
an additional 5 hr. period. The reaction mixture was washed
with water, dried and stripped of solvent by rotary
evaporation. The addition product (50.5 g.), m.p. 63-64C
was obtained from the residue by extraction with
cyclohexane. Recrystallization from benzene gave a white
crystalline solid, m.p. 64-65C. The infrared spectrum was
consistent with the adduct structure. Elemental analysis
was satisfactory:
C ~ N
Analysis calculated for Cl oHl lO2N3 :58-53 5.40 20.48
Found : 58.8l 5.46 20.4
EXAMPLE 4
Evaluation of Products
The alkyl dimexcapto thiadiazole used in the
blends described below was purchased as Amoco l50. lt is
the product of Example VI of U.S. Patent No. 3,7l9,l25.
Three diffexent blends, made up as follows, were
evaluated in various tests:
1. A solvent paraffinic neutral mineral oil
(viscosity: 35 cSt at 38C) with 0.55% of a
standard additive system and comprising (1)
60% of the reaction product of 1 mole of butyl
vinyl ether and l mole of toluotriazole and
(2) 40% of the alkyl dimercapto thiadiazole.
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F-0152 2. A blend containing highly ~efined base stock
(viscosity: 35 cSt at 38C; viscosity
index of 111 ) blended with a standard additive
system.
3. A blend containing 25% of l and 75% of 2.
These tests included determination of
neutralization number (NN) foaming tendency, rusting, coppe~
corrosion and rotary bomb oxidation test (RBOT).
Copper Co _osion Test~- ASTM D-130
A polished copper strip is immersed in the sample
and heated at a tempexature and for a time characteristic of
the material being tested. At the end of this period the
copper strip is removed, washed, and compared with the ASTM
Copper Strip Corrosion Standards. A temperature of 120k
and a time of 3 hours were used.
Rotary Bomb Oxidation Test ~BOT) - ASTM D-2272
The test oil, water, and copper catalyst coil,
contained in a covexed glass container, are placed in a bomb
equipped with a pressure gage. The bomb is charged with
oxygen to a pressure of 620 kPa., placed in a
constant-temperatuxe oil bath set at 150C, and rotated
axially at l00 rpm at an angle of 30 from the horizontal.
The time for the test oil to react with a given volume of
oxygen is measured, completion of the time being indicated
by a specific drop in pressure, here a pressure drop of 172
kPa.
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F-0152 Rust Test A~TM D-665
The method involves stirring a mixture of 300 ml.
oE the oil under test with 30 ml. of distilled or synthetic
sea water, as requiredl at a temperature of 60C with a
cylindrical steel specimen completely immersed therein. It
is customary to run the test for 24 hours; however, the test
period may, at the discretion of the contracting parties, be
for a shorter or longer period. The test was run fox 24
hours using synthetic sea water at 60C.
Foam Test - ASTM D-892
The sample, maintained at a temperature of 24C is
blown with air at a constant rate for 5 minutes, then
allowed to settle for 10 minutes. The volume of foam is
measured at the end of both periods. The test is repeated
on a second sample at 93C and then, after collapsing the
foam, at 24C.
The results are summarized in Table l.
TABLE l
Blend 1 _ 2 3 _
NN 0.07 0.20 0.32
Foam Test l80/0 225/0 l90/0
Rust Test Pass Pass Pass
Copper Corrosion
Test lB lA lA
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RBOT, Min. 390/425 260 ll0
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F-0152 Other blends were made up as follows:
1. A base fluid containing 99.45V/o of a 35 cSt
(38C) turbine base oil and a standard
additive package.
2. Blend 1 plus 0.05% by weight of a mixture
containing (l) 60% by weight of the reaction
product of 1 mole of butyl vinyl ether and
l mole of tolyltriazole and (2) 40% by weight
of the alkyl dimercapto thiadiazole,
3. Blend l plus 0.05% by wéight of the reaction
product (l) of Blend 2,
4. Blend l plus 0.05% by weight of the alkyl
dimercapto thiadiazole of Blend 2.
These were evaluated in the tests described below.
Total Oxidation Products'Test'(CIGRE) - IP'280
Oxygen is passed for 164 hours through a sample of
the oil with the added soluble metal catalyst, ixon and
coppex and maintained at 120~. The volatile acid products,
the acidity of the oil and the sludge formed are determined.
If the measuxement of the length of time to obtain a
pronounced change in the rate of evolution of volatile acid '
is required, an acidity/time curve can be obtained by daily
determinations of the volatile acids. The catalyst is a
soluble copper salt.
Rotary'Bomb Oxidation Test'(RBOT~ --ASTM'D-2272
- Described above.
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F-0152 Turbine Oil Stability Test (TOST) - ASTM D-943
The oil sample is subjected to a temperature of
90C in the presence of water, oxygen and an iron-copper
catalyst. The test was carried out for 2500 hours.
The results were as follows: j
TABLE 2
Blend l 2 3 4
CIGRE,
Total oxidation
Pxoducts 5.53 0.29 l.l5 5.22 t
RBOT Min. 3l5 440 400 395
TOST %
~ludge, ~y wt. 0.76 0.l6 0.28 0.~6
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