A water soluble lubricating additive for water-based fluids used in metalworking operations comprising a polyoxyalkylene sulfur compound selected from the group consisting of alkyl polyoxyalkylene sulfides, alkyl polyoxyalkylene sulfoxides and mixtures thereof. In an alternate embodiment of this invention, dithiodiglycol may be combined with a polyoxyalkylene sulfur compound selected from the group consisting of alkyl polyoxyalkylene sulfides, alkyl polyoxyalkylene sulfoxides and mixtures thereof to produce said water soluble lubricating additive.

This invention relates to compositions used in metalworking operations. In 
one aspect, this invention relates to compositions which are useful as 
lubricating additives for water-based fluids used in metalworking 
operations. In another aspect, this invention relates to compositions 
which are useful as extreme pressure (EP) lubricating additives for 
water-based fluids used in metalworking operations. 
In metalworking operations, such as cutting, drilling, drawing, tapping, 
polishing, grinding, turning, milling and the like, it is customary to 
flood the tool and the work piece with a coolant for the purpose of 
carrying off heat which is produced during the operation. Such coolants 
are typically water-based or are based upon liquid organic compounds. 
In addition to carrying off heat which is produced during metalworking 
operations, however, it is also desirable that the fluids used in such 
operations be capable of reducing friction between the tool and the work 
piece. Typically, the coolants used in metalworking operations do not 
possess either lubricity (low load) or extreme pressure (high load) 
lubricating properties. Therefore, it is customary to employ these 
coolants in combination with various lubricating additives which do 
possess such properties. 
In addition to lubricating additives, however, many other additives are 
also used to provide water-based metalworking fluids with various 
desirable characteristics. Thus, such a water-based fluid will typically 
contain, among other additives, small amounts of at least one lubricity 
additive, an extreme pressure additive, a rust controlling additive, a pH 
buffering additive, a corrosion inhibitor, and a biocide. Therefore, the 
lubricating additives used in a water-based metalworking fluid are 
preferably water soluble, and thus suitable for use in a water-based fluid 
without the presence of an emulsifier, and compatible with other commonly 
used additives. 
It is thus an object of this invention to provide water soluble lubricating 
additives which, when added to water-based fluids used in metalworking 
operations, enhance the lubricating characteristics of such fluids and are 
compatible with other additives commonly used with such fluids. 
In accordance with the present invention, a polyoxyalkylene sulfur compound 
selected from the group consisting of alkyl polyoxyalkylene sulfides, 
alkyl polyoxyalkylene sulfoxides and mixtures thereof is added to 
water-based fluids used in metalworking operations, thereby improving the 
lubricating characteristics of such fluids. 
In an alternate embodiment of the invention, a polyoxyalkylene sulfur 
compound selected from the group consisting of alkyl polyoxyalkylene 
sulfides, alkyl polyoxyalkylene sulfoxides and mixtures thereof is 
combined with dithiodiglycol (also known as di-(2-hydroxyethyl) disulfide 
or diethanol disulfide) to produce a water soluble lubricating additive. 
When said additive is added to water-based fluids used in metalworking 
operations the lubricating characteristics of such fluids are improved. 
Other objects and advantages of the invention will be apparent from the 
foregoing brief description of the invention and the appended claims as 
well as the detailed description of the invention which follows. 
The lubricating additive of this invention comprises a polyoxyalkylene 
sulfur compound selected from the group consisting of alkyl 
polyoxyalkylene sulfides, alkyl polyoxyalkylene sulfoxides and mixtures 
thereof. Any suitable alkyl polyoxyalkylene sulfide may be used in 
accordance with this invention. Suitable alkyl polyoxyalkylene sulfides 
can be prepared by the reaction of an alkyl mercaptan and an alkylene 
oxide. A generic formula for a suitable alkyl polyoxyalkylene sulfide is 
as follows: 
EQU R--S--(R'O).sub.x --H 
wherein R is a hydrocarbyl group having 1 to 20 (preferably 12) carbon 
atoms; R' is a hydrocarbyl group having 1 to 5 (preferably 2) carbon 
atoms; and x=1 to 15 (preferably 3 to 12). 
Examples of suitable alkyl polyoxyalkylene sulfides include: t-dodecyl 
polyoxyethylene sulfide, n-dodecyl polyoxyethylene sulfide, decyl 
polyoxyethylene sulfide, eicosyl polyoxyethylene sulfide, dodecyl 
polyoxypropylene sulfide, tetradecyl polyoxypropylene sulfide, octadecyl 
polyoxypropylene sulfide, decyl polyoxybutylene sulfide, dodecyl 
polyoxybutylene sulfide and undecyl polyoxybutylene sulfide. A preferred 
alkyl polyoxyalkylene sulfide is t-dodecyl polyoxyethylene sulfide with 
either seven (7) or nine (9) oxyethylene repeat units. 
Any suitable alkyl polyoxyalkylene sulfoxide may be used in accordance with 
this invention. Suitable alkyl polyoxyalkylene sulfoxides may be prepared 
by oxidizing suitable alkyl polyoxyalkylene sulfides. A generic formula 
for a suitable alkyl polyoxyalkylene sulfoxide is as follows: 
##STR1## 
where R, R' and x are as previously defined. 
Examples of suitable alkyl polyoxyalkylene sulfoxides include: t-dodecyl 
polyoxyethylene sulfoxide, n-dodecyl polyoxyethylene sulfoxide, decyl 
polyoxyethylene sulfoxide, eicosyl polyoxyethylene sulfoxide, dodecyl 
polyoxyethylene sulfoxide, tetradecyl polyoxypropylene sulfoxide, 
octadecyl polyoxypropylene sulfoxide, decyl polyoxybutylene sulfoxide, 
dodecyl polyoxybutylene sulfoxide and undecyl polyoxybutylene sulfoxide. A 
preferred alkyl polyoxyalkylene sulfoxide is t-dodecyl polyoxyethylene 
sulfoxide with either five (5) or nine (9) oxyethylene repeat units. 
In an alternate embodiment of this invention, dithiodiglycol (also known as 
di-(2-hydroxyethyl) disulfide or diethanol disulfide) is combined with a 
polyoxyalkylene sulfur compound selected from the group consisting of 
alkyl polyoxyalkylene sulfides and alkyl polyoxyalkylene sulfoxides to 
form a water soluble lubricating additive. Dithiodiglycol, which is 
commercially available from both Phillips Chemical Company, Bartlesville, 
Okla. and Pennwalt Company, Philadelphia, Pa., may be prepared in 
accordance with the disclosure set forth in U.S. Pat. No. 4,250,046. Since 
dithiodiglycol is commercially available and may be prepared by 
conventional methods and since such preparation does not play any part in 
the present invention, the preparation of dithiodiglycol will not be more 
fully discussed hereinafter. 
The dithiodiglycol and the polyoxyalkylene sulfur compound selected from 
the group consisting of alkyl polyoxyalkylene sulfides, alkyl 
polyoxyalkylene sulfoxides and mixtures thereof may be combined in any 
suitable manner and under any suitable conditions. Preferably, the 
disulfide and the polyoxyalkylene sulfur compound are mixed together using 
conventional mixing equipment until a substantially clear, homogenous 
composition is obtained. It is not believed that the conditions of mixing 
such as temperature or pressure have any effect on the formation of the 
composition. Optionally, water can be present in the composition. 
Any suitable amount of dithiodiglycol may be present in the composition 
comprising dithiodiglycol and a polyoxyalkylene sulfur compound selected 
from the group consisting of alkyl polyoxyalkylene sulfides, alkyl 
polyoxyalkylene sulfoxides and mixtures thereof. Preferably, the 
concentration of the dithiodiglycol in said composition is in the range of 
about 5 weight-% to about 95 weight-% based upon the weight of the 
composition. More preferably, said concentration will be in the range of 
about 10 weight-% to about 50 weight-% based upon the weight of the 
composition. 
The lubricating additives of the present invention may be utilized to 
improve either the lubricity (low load) or extreme pressure (high load) 
lubricating properties of any suitable water-based fluid used in 
metalworking operations. 
Any suitable amount of the lubricating additives of this invention may be 
added to a water-based metalworking fluid. The amount added would 
generally be sufficient to result in a concentration of the lubricating 
additive in the water-based metalworking fluid in the range of about 0.01 
weight-% to about 10 weight-% based upon the combined weight of the 
lubricating additive and the water-based fluid. More preferably, said 
concentration will be in the range of about 0.02 weight-% and about 2.0 
weight-% based upon the combined weight of the lubricating additive and 
the water-based fluid. 
In addition to the lubricating additives of the present invention, the 
water-based metalworking fluid may contain other other conventional 
additives such as additional lubricating additives, rust preventatives, pH 
modifiers, corrosion inhibitors and biocides. Such conventional additives 
do not play a part in the present invention, however, and they are well 
known in the art; therefore, they will not be more fully discussed 
hereinafter.

The following examples are presented in further illustration of the 
invention. 
EXAMPLE I 
This example illustrates the use of alkyl polyoxyethylene sulfoxides as 
lubricating additives in aqueous solutions. Several aqueous solutions were 
tested in a Falex EP (extreme pressure) test in accordance with ASTM 
D-3233. Each of the aqueous solutions tested contained about 0.8 weight-% 
of the indicated additive. The results of these tests are presented in 
Table I. 
TABLE I 
______________________________________ 
Fail 
Load 
Run Solution (lbs) 
______________________________________ 
1 (Control) water 300 
2 (Invention) 
t-dodecyl polyoxyethylene sulfoxide-5.sup.(a) 
4250 
3 (Invention) 
n-dodecyl polyoxyethylene sulfoxide-5 
4000 
4 (Invention) 
n-butyl polyoxyethylene sulfoxide-6 
500 
5 (Invention) 
t-dodecyl polyoxyethylene sulfoxide-7 
3750 
6 (Invention) 
n-dodecyl polyoxyethylene sulfoxide-7 
.sup. 500.sup.(b) 
7 (Invention) 
n-dodecyl polyoxyethylene sulfoxide-7 
2000 
8 (Invention) 
n-dodecyl polyoxyethylene sulfoxide-7 
2250 
9 (Invention) 
t-dodecyl polyoxyethylene sulfoxide-9 
2500 
10 (Invention) 
n-dodecyl polyoxyethylene sulfoxide-9 
3250 
11 (Invention) 
t-dodecyl polyoxyethylene sulfoxide-12 
1000 
______________________________________ 
.sup.(a) the number at the end of the solution description represents the 
number of ethylene oxide equivalents that were reacted with an alkyl 
mercaptan to form the preoxidation alkyl polyoxyethylene sulfide 
.sup.(b) considered to be an anomalous result in view of runs 7 and 8 
The test data presented in Table I demonstrates that alkyl polyoxyethylene 
sulfoxides are effective extreme pressure lubricating additives. The data 
also shows that an alkyl polyoxyethylene sulfoxide containing 5 
oxyethylene repeat units (runs 2 and 3) is the most preferred lubricating 
additive. 
EXAMPLE II 
This example illustrates the use of alkyl polyoxyethylene sulfoxides and 
alkyl polyoxyethylene sulfides as lubricating additives in aqueous 
solutions containing other common additives such as a rust inhibitor, a 
biocide, a lubricity agent and an amine (for pH adjustment). The two 
aqueous solutions used in this example comprised the following additives: 
Solution A: 
0.8 wt-% triethanolamine, used for pH adjustment; 
0.3 wt-% Synkad 500.RTM., a carboxylic acid salt rust inhibitor, marketed 
by Keil Chemical; and, 
0.05 wt-% Biopan P-1487.RTM., a biocide marketed by Keil Chemical; 
Solution B: 
0.08 wt-% triethanolamine; 
0.15 wt-% octanoic acid, used as a lubricity agent; and, 
0.6 wt-% polypropylene glycol, used as a lubricity agent. 
Solution A was combined with 0.8 weight-% of either an alkyl 
polyoxyethylene sulfoxide or an alkyl polyoxyethylene sulfide to form 
solutions which were then tested in a Falex EP test in accordance with 
ASTM D-3233. Likewise, Solution B was combined with varying amounts (as 
indicated below) of either an alkyl polyoxyethylene sulfide or an alkyl 
polyoxyethylene sulfoxide to form several solutions which were also tested 
in a Falex EP test. Both Solution A and Solution B were also tested. The 
results of these tests are presented in Table II. 
TABLE II 
______________________________________ 
Fail 
Load 
Run Solution (lbs) 
______________________________________ 
12 Solution A 750 
(Control) 
13 Solution B 2100 
(Control) 
14 Solution A + t-dodecyl POE.sup.(a) sulfoxide-3 
3500 
(Invention) 
15 Solution A + n-dodecyl POE sulfoxide-3 
3750 
(Invention) 
16 Solution B'.sup.(b) + t-dodecyl POE sulfide-3 
4250+ 
(Invention) 
17 Solution B".sup.(c) + t-dodecyI POE sulfide-3 
4250+ 
(Invention) 
18 Solution A + t-dodecyl POE sulfoxide-5 
3750 
(Invention) 
19 Solution A + n-dodecyl POE sulfoxide-5 
3750 
(Invention) 
20 Solution A + t-dodecyl POE sulfide-7 
3750 
(Invention) 
21 Solution B' + t-dodecyl POE sulfide-7 
4250 
(Invention) 
22 Solution B" + t-dodecyl POE sulfide-7 
4250+ 
(Invention) 
23 Solution B' + t-dodecyl POE sulfoxide-7 
3800 
(Invention) 
24 Solution B" + t-dodecyl POE sulfoxide-7 
4250+ 
(Invention) 
25 Solution A + t-dodecyl POE sulfoxide-9 
2500 
(Invention) 
26 Solution A + n-dodecyl POE sulfoxide-9 
3750 
(Invention) 
27 Solution B' + t-dodecyl POE sulfide-12 
4250+ 
(Invention) 
28 Solution B" + t-dodecyl POE sulfide-12 
4250+ 
(Invention) 
______________________________________ 
.sup.(a) polyoxyethylene 
.sup.(b) B' contains 0.5 weight % of the sulfoxide or sulfide additive 
.sup.(c) B" contains 2.0 weight % of the sulfoxide or sulfide additive 
The test data presented in Table II demonstrates that both alkyl 
polyoxyethylene sulfoxides and alkyl polyoxyethylene sulfides are 
effective extreme pressure lubricating additives in aqueous solutions 
containing various traditional additives. 
EXAMPLE III 
This example illustrates the use of alkyl polyoxyethylene sulfoxides as 
lubricating additives in aqueous solutions which contain an additional 
lubricating additive. The aqueous solutions, which were tested in a Falex 
EP test in accordance with ASTM D-3233, comprised 0.8 weight-% of each of 
the indicated additives. The results of these tests are presented in Table 
III. 
TABLE III 
______________________________________ 
Fail 
Load 
Run Solution (lbs) 
______________________________________ 
29 (Control) Actramide.sup.(a) 3000 
30 (Invention) 
Actramide + n-dodecyl POE sulfoxide-5 
4000 
31 (Invention) 
Actramide + t-dodecyl POE sulfoxide-9 
3750 
32 (Invention) 
Actramide + n-dodecyl POE sulfoxide-9 
3750 
______________________________________ 
.sup.(a) Actramide 189; a lubricity agent, marketed by Arthur C. Trask 
Operation, The Southland Corporation Chemical Division, Chicago, Illinois 
The data presented in Table III demonstrates that alkyl polyoxyethylene 
sulfoxides are effective extreme pressure lubricating additives when added 
to an aqueous solution which already contains other lubricating additives. 
Based upon this data and the data set forth in Table II, it is believed 
that alkyl polyoxyethylene sulfides would also be effective extreme 
pressure lubricating additives in such solutions. 
Furthermore, based upon this data and the data set forth in Table II, it is 
also believed that mixtures of alkyl polyoxyethylene sulfides and alkyl 
polyoxyethylene sulfoxides would be effective extreme pressure lubricating 
additives in aqueous solutions. 
EXAMPLE IV 
This example demonstrates the use of alkyl polyoxyethylene sulfoxides, in 
combination with dithiodiglycol (HO--C.sub.2 H.sub.4 --S--S--C.sub.2 
H.sub.5 --OH; also known as di-(2-hydroxyethyl) disulfide and diethanol 
disulfide; marketed by Phillips Chemical Company, Bartlesville, Okla.), as 
a lubricating additive in aqueous solutions. The aqueous solutions, which 
were tested in a Falex EP test in accordance with ASTM D-3233, contained 
0.8 weight-% of each of the indicated additives. The results of these 
tests are presented in Table IV. 
TABLE IV 
______________________________________ 
Fail 
Load 
Run Solution (lbs) 
______________________________________ 
33 dithidiglycol 500 
(Control) 
34 t-dodecyl POE sulfoxide-9 
2500 
(Invention) 
35 dithidiglycol + t-dodecyl POE sulfoxide-9 
3750 
(Invention) 
36 n-dodecyl POE sulfoxide-9 
3250 
(Invention) 
37 dithidiglycol + n-dodecyl POE sulfoxide-9 
4250 
(Invention) 
______________________________________ 
The data presented in Table IV demonstrates that the aqueous mixtures of 
dithiodiglycol and an alkyl polyoxyethylene sulfoxide are more effective 
lubricants than aqueous solutions of either component alone. Furthermore, 
by comparing the data of runs 33 and 34 with run 35 and runs 33 and 36 
with run 37, it can be seen that the lubricating effectiveness of the 
aqueous mixtures of dithiodiglycol and an alkyl polyoxyethylene sulfoxide 
is more than merely the additive effectiveness of the two components 
alone. Based upon this data and the data presented in Table II, it is 
believed that an aqueous mixture of dithiodiglycol and either an alkyl 
polyoxyethylene sulfide or a mixture of an alkyl polyoxyethylene sulfide 
and a alkyl polyoxyethylene sulfoxide would also demonstrate this 
synergistic effect. 
While this invention has been described in detail for the purpose of 
illustration, it is not to be construed as limited thereby but is intended 
to cover all changes and modifications within the spirit and scope 
thereof.