Note: Descriptions are shown in the official language in which they were submitted.
1.3~
F-3880
MERCAPTO-THIADIAZOLE REACTION PRODUCTS AS
MULTIFUNCTIONAL LUBRICANT ADDITIVES AND
COMPOSITIONS THEREOF
This invention is directed to reaction products of
mercapto-thiadiazoles, mercaptans and thionyl chloride as
zinc/phosphorus-free antiwear agents and antioxidants.
Replacement of zinc phosphorodithioates by
zinc/phosphorus-free antiwear additives in circulating oils, gear
oils and various other lubrlcating systems is considered highly
deslrable because of environmental considerations and the potential
electrolytic corrosivity of zinc salts. An additive system whlch in
addition to antiwear activity exhibits antioxidant activity and
copper passivation is highly desirable. The condensates of the
present invention provide outstanding FZG gear performance, low
Four-ball wear and antioxidant activity. Furthermore, they contain
no corrosive sulfur.
Various reaction products of mercapto and dimercapto-
thiadiazoles (DMTD) are known in the art. For example, reactionproducts of 2,5-dimercapto-1,3,4-thiadiazole are disclosed in U.S.
Patent 4,128,510 as being useful as cross-linking agents ~or
halogen-containin~ polymers. ~.S. P~`lten~ ~,382,869 dL.sclos~s r~ac~.ion
products of mercaptothiadiazoles with hydroxyl-containing compounds
as friction reducing and corrosion-inhibiting additives for
lubrlcant oils. Although reaction products containing the
mercapto-1,3,4-thiadiazole structure has found widespread use as
lubricant antioxidants and metal passivators, the compositions and
the utility of the reaction products described in this patent
application are believed to be unknown heretofore in the art.
This invention provides a product of reaction having
multifunctional antiwear/extreme pressure (EP) and antioxidation
., 3~
~.;3~J~ 8
F-3880 - 2 -
characteristics prepared by reacting a mercapto or dimercapto
thiadiazole with a mercaptan and thionyl chloride.
This invention further provides a process of making the
above-described product.
This invention also provides lubricant compositions
comprising a lubricant and an antiwear/extreme pressure (EP) and/or
antioxidant amount of the product of reaction made by reacting a
mercapto-thiadiazole with a mercaptan and thionyl chloride. The
reaction may take place in the presence of a suitable stabilizing or
dispersing agent or said agent may be contacted at the conclusion of
the reaction.
rhe synthesis and evaluation of derivatives of mercapto
thiadiazoles, particularly 2,5-dimercapto-1,3,4 thiadiazole (DMTD)
as potential no-phosphorus multifunctional additives and replacement
for Zn phosphorodithioates in circulating oils, gear oils, and other
lubricating systems is an attractive and novel route for obtaining
these goals.
In general, the additive products of the invention are
synthesized by the condensation of a mercapto-thiadiazole, for
example, 2,5-dimercapto-1,3,4-thiadiazole with mercaptans and
thionyl chloride (SOC12).
Any appropriate mercapto-thiadiazole may be used herein.
Some suitable examples include but are not limited to
3,4-dimercapto-1,2,5-thiadiazole, 3,5-dimercapto- 1,2,4-thiadiazole,
4,5-dimercapto-1,2,5-thiadiazole, 4,5-dimercaptobenzo
1,2,3-thiadiazole, 4,7-dimercaptobenzo 1,2,3-thiadiazole,
4,6-dimercaptobenzo 1,2,3-thiadiazole, 5,6-dimercaptobenzo
1,2,3-thiadiazole, 5,7-dimercaptobenzo 1,2,3-thiadiazole,
6,7-dimercaptobenzo 1,2,3-thiadiazole, 4,5~dimercaptobenzo
2,1,3-thiadiazole, 4,6-dimercaptobenzo 2,1,3-thiadiazole,
5,6-dimercaptobenzo 2,1,3-thiadiazole, 5,7-dimercaptobenzo
2,1,3-thiadiazole, 6,7-dimercaptobenzo 2,1,3-thiadiazole.
Especially preferred is 2,5-dimercapto- 1,3,4-thiadiazole.
~ 3~
F-3880 - 3 -
Suitable mercaptans include but are not limited to Cl to
about ~2 alkyl mercaptans. Especially preferred are t-nonyl and
hexadecyl mercaptans.
Optionally a stabilizing or dispersing agent may be used in
the synthesis process. The reaction process in accordance with the
lnvention may be carried out in the presence of such agent or the
product of reaction thereof may be treated with such agent. Any
suitable agent known in the art that would disperse the reaction
medium and stabilize the products without having a detrimental
effect upon the desired reaction may be used. Particularly
qualified are thiadiazoles such as 2,5-bis(t-nonyl-thio)-1,3,4-
thiadiazole and non-emulsive amines such as"Primene 81R"amine.
Generally any t-alkylthio-thiadiazole may be used. "Primene 81R"*
amine is a partlcularly preferred non-emulslve amine. It is
believed to be a mixture of primary aliphatic amines of
predominantly C12 to C14 t-alkyl groups. It is more fully
r~ported in U.S. Patent 3,224,957 of E.A. ~t, issl}~ Deo~er
21, 1965 .
The reaction conditions are based primari~ly on the
particular reactants. Usually, however, the temperature may vary
20 from about 50 to about 120C, the pressure fr~m ambient to 1030 kPa if
desired, and the tLme from about 1 to about 8 hours or more depending on
specific reactants.
The molar ratio of reactants
DMTD/mercaptan/thlonylchloride varies ~rom about 1:2:1.5 ko about
25 1:12:8. The amount of stablllzing or dispersing agent when used may
vary from about 5 to about 60 wt.% based on the weight of the
condensation product. Preferably from about 10 to about 50 wt.X is
used.
The lubricants which may be used with the additives
(reaction products) of thls invention are mineral and synthetic
lubricating oils, mixtures thereof and greases made therefrom. The
mineral oils will be understood to include not only the paraffinic
members, but also the naphthenic members. By synthetic oils are
meant synthetic hydrocarbons, polyalkylene oxide oils, polyacetals,
,C '
* Trademark
~ 3~?~ 3~
F-3880 - 4 -
polysilicones and the like, as well as synthetic ester oils.
Included among the latter type are those esters made from monohydric
alcohols and polycarboxylic acids, such as 2-ethyl-hexylazelate and
the like. Also included are those esters made from polyhydric
alcohols and aliphatic monocarboxylic acids. Those of this group
are especially important and in this group are found esters prepared
from (1) the trimethylols, such as the ethane, propane and butane
derivatives thereof, (2) 2,2-disubstituted propane diols and (3) the
pentaerythritols reacted with aliphatic monocarboxylic acids
containing from about 4 to 9 carbon atoms. Mixtures of these acids
may be used to prepare the esters. Preferred among the esters are
those made from pentaerythritol and a mixture of C5-Cg acids.
As has been disclosed hereinabove, the reaction products
are useful as antiwear/EP and antioxidant agents. They are added to
the lubricating medium in amounts sufficient to impart such
properties to the lubricant. More particularly, such properties
will be imparted to the lubricant by adding from about 0.01% to
about 10% by weight, preferably from about 0.01% to about 3%, of the
neat product.
Having discussed the invention in broad and general terms,
the following are offered to illustrate it. It is to be understood
that the examples are merely illustrative and are not intended to
limit the scope of the invention.
EXAMPLE 1
DMTD, SOC12 and t-nonylmercaptan condensate (molar ratio
1:2.2:2) in 2,5-bis(t-nonylthio)-1,3,4-thiadiazole dispersing medium
( 50 wt.%).
50 gms of 2,5-bis(t-nonylthio)-1,3,4-thiadiazole,
t-nonylmercaptan (32 gms., O.2 mole) and DMTD
(2,3-dimercapto-1,3,4-thiadiazole; 15 gms., 0.1 mole) are placed in
a flask equipped with dropping funnel, reflux condenser,
thermometer, mechanical stirrer, a nitrogen inlet tube and outlet
tube leading from the condenser to scrubbers containing aqueous NaOH
,
~ 3~3~3~
F-3880 - 5 -
solution. The reaction system is protected from exposure to moist
air by means of drying tubes.
The mixture is heated to 85C with stirring under a dry
nitrogen stream. SOC12 (26.18 gms.; 0.22 mole) is cautiously
added dropwise over a period of thirty minutes. The reaction is
strongly exothermic and is able to retain the temperature of the
reaction mixture at 85-88C without external heating throughout most
of the addition period. The reaction mixture which is a homogeneous
fluid is heated at 85C for two additional hours after completion of
lo the SûC12 addition. It is subsequently placed under house vacuum
and heated to final temperature of 105C. The mixture is cooled to
room temperature and treated with n-hexane (300 ml). The solution
is heated at 70C for a few minutes, is cooled and filtered. A
minimal quantity of solids ( 0.69) is collected on the filter. The
filtrate is mixed with 200 ml of 5 wt.~ aqueous NaOH solution and
warmed to 55C. The organic layer is separated. The aqueous layer
is extracted with an additional quantity of n-hexane (50 ml). The
combined organic layers are washed with water, dried and stripped of
solvent and volatiles under house vacuum and final pot temperature
86C. The residue, a clear purple fluid, weighed 102.87 gms. It
was readily soluble in 100 cSt oil, n-hexane, acetone, dimethyl
fluoride (DMF) but sparingly soluble in water, acetonitrile and
dimethyl sulfoxide (DMSO). Infrared (IR) Spectrum was consistent
with anticipated structure of poly dithionyl sulfoxide.
EXAMPLE 2
DMTD, SOC12, t-nonylmercaptan (molar ratio 1:2.2:2)
condensate treated with"Primene 81R Amine"(10 wt.~).
DMTD (2,3 dimercapto-1,3,4 thiadiazole; 759, 0.5 mole),
t-nonylmercaptan (1609, 1.0 mole) and toluene (500 ml) are placed in
a flask equipped with dropping funnel, mechanical stirrer, reflux
condenser, thermometer, nitrogen inlet tube and outlet tube leading
from the condenser to scrubbers containing aqueous solution of
- NaOH. The reaction system is protected from exposure to moist air
by means of drying tubes.
* Trademark
1.3~38~
`~
F-3880 - 6 -
The mixture is heated to 75C (with stirring) under a light
stream of dry nitrogen SOC12 (130.9g, l.l mole) diluted with 150
ml of toluene is added dropwise over a period of one hour. The
temperature of the reaction mixture is maintained at 75-80C
throughout the SOC12 addition and for two additional hoursO The
solvent and any volatiles present are distilled under reduced
pressure-house vacuum. the final pot temperature is allowed to
reach llO~C. The res~due (278 gms) ls cooled to room temperature
and treQt~d wlth ono liter of n-h~x~no ~nd 600 ml Of 5 wt,% aquoous
NaOH solution. the organic layer is separated. The aqueous layer
ls extracted wlth an addltlonal ~uuntlty of hexane (200 ml). The
combined extracts are washed with water and dried. "Primene 81R~*
amine (27.8 gms) is added. the clear solution is stripped of
solvent and any volatiles under house vacuum and final pot
S temperature is 100C. The residue, a clear purple fluid, we~ghs 288
gms. It is readily soluble in lOO cst oil, n-hexane, acetone,
methyl ethyl ketone (MEK) and DMF. IR spectrum ls ln agreement wlth
anticipated structure.
The condensation react~on, believed novel, is applicable
over a broad spectrum of uses. The polarity of the sulfoxide groups
in the vicinlty of the thiadiazole moiety enhances the adhesion to
metals through a potential bldentate ligant formation. This
arrangement protects metal surfaces through strong
adsorption-chemisorption and consequently increases the antiwear-EP
activity of the aggregate
Evaluation of Products
The examples in accordance with the invention were blended
into a zinc/phosphorus-free heavy duty circulating oil formulation
deslgnated Test Oil #l and 2 and evaluated as to gear test wear,
antiwear/EP characteristics and antioxidation properties. See
Tables l and 2.
The formulation was tested for gear wear protection
according to the FZG Gear Test (DIN-51.354). In this test,
* Trademark
- ` ~ 3~?~38~
F-3880 ~ 7 -
dip-lubricated gears are weighed and operated at a fixed speed and
fixed initial oil temperature (90C) in the gear oil under test.
The load on the teeth is increased in increments. After each load
stage, the weight changes are determined and recorded. The results
are reported in Table 1 and Table 2. The higher the Fail Stage
value the better the material. The lower the wear value the better
the product.
The formulation was also tested for its antiwear properties
according to the Four-~all Wear Test. The results are set forth in
Table 2. The products of the examples and comparative examples were
tested in the 4-ball test using a modified 4-ball machine. In this
test, three stationary balls are placed in a lubricant cup and a
lubricant containing the additive to be tested is added thereto~ A
fourth ball is placed on a chuck mounted on a device which can be
used to spin the ball at known speeds and loads. Various
percentages by weight of each product was placed in the blend. The
samples were tested at 54C (130F) at a load of 20 kg and 1800 rpm
for 60 minutes.
The formulation was tested for its antioxidation
characteristics in accordance with the Rotary 80mb Test (R80T-ASM
D-2272). The test oil, water, and copper catalyst coil, contained
in a covered glass container, are placed in a bomb equipped with a
pressure gauge. The bomb ls charged with oxygen to a pressure of
620 kPa (90 psi), placed in a constant temperature oil bath set at
150C, and rotated axially at 100 rpm at an angle of 3û 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.
1.3~
F-3880 - 8 -
.
TABLE 1
ZINC/PHOSPHORUS-FREE HEAVY CIRCULATING OIL FORMULATIONS
FZG
Fail Wear
Composition Stage mg
Reference Oils
A Test Oil #1 - 0.25% Zn (DTP)2 11 125
- 1.00% Zn (DTP)2 11 72
Test Oil #1 less Zn (DTP)2 8 __
+ 1% (1) 9 349
+ 1% (2) 10 118
Thionyl Chloride Reaction Products
+ 1% (3) 12 45
+ 1% Ex. 1 12 40
~ 1% Ex. 2 12 37
.
(1) Comparative Example: sulfurized olefin
(2) Comparative Example: mercaptobenzothiazole type antiwear
agent
(3) Reaction prod~ct of SOC12/CgSH/DMTD without dispersing
medium.
~.3~ 3~
F-3880 - 9 -
TAPLE 2
ZINC/PHOSPHORUS-FREE CIRCULATING OIL FORMULATIONS
Test Oil #2 less Zn(DTP2 plus:
ATest Oil #2 EXAMPLE EXAMPLE EXAMPLE EXAMPEE
~0.09% 3 2 2
Performancé Tests Zn(OTP)~] o~-o9% 0.09% 0.2% _ 0.2%
FZG Gear Test
Fail Stage 8/9 9 9 10 9
Wear, mg 20 30 51 -- 21
4-Ball Wear
Scar Diam, mm0.25 0.26 -- 0.27 0.25
RBOT, mlnutes225 365 -- 415 --
_
(3) Reaction product of SOC12/CgSH/OMTD without dispersing
medium.
A Test Oils #1 and #2 represent typical rust inhibited
circulatory oils used to lubricate industrial equipment such as
pumps, gears, etc.
~ ~ 3~'~13~
F-3880 - 10 -
From the above data it is quite clear that the reaction
products (additives) of the present invention provide noticably
outstanding FZG gear performance and antiwear/EP characteristics but
also exhibit significant antioxidation properties.
These additives, in accordance with the invention, prepared
by reaction of thionyl chloride with mercapto-thiadiazole and
mercaptan, provide outstanding FZG gear performance, low Four-ba
wear and a boost in oxidation stability. Accordingly they show
promise as replacements for zinc dithiophosphate antiwear agents
used in heavy circulating oil formulations.
Although the present invention has been described with
preferred embodiments, it is to be understood that modifications and
variations may be resorted to, without departing from the spirit and
scope of this invention, as those skilled in the art will readily
understand. Such modifications and variations are considered to be
within the purview and scope of the appended claims.
