Aqueous lubricant

A lubricant concentrate is provided for forming stable, translucent oil-in-water emulsions upon dilution with a major part of water. The concentrate comprises a suitable base oil blended with polyisobutylene and an emulsifier/dispersant and antiwear/antirust inhibitor system. Typical emulsifier/dispersants include the metal soaps of rosin acids, the alkylene oxide condensation products of a fatty amine or the reaction product thereof with a polyalkenylsuccinic acid or anhydride. Zinc dialkyldithiophosphates and metal dialkylnaphthalene sulfonates are useful antiwear and antirust inhibitors.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to water-content hydraulic fluids and more 
particularly a concentrate for addition to water for the preparation of 
water-content hydraulic fluids. The invention further relates to a method 
of lubricating with water-content hydraulic fluids which may contain up to 
95% or more water. 
2. Description of the Prior Art 
Heretofore, the technology of lubrication generally centered about the 
development of petroleum oils for lubricants or greases and the 
application of the lubricant so prepared to the point of wear or friction. 
Innumerable and complex lubricating compositions have been proposed 
comprising, generally, a hydrocarbon oil, a bodying or thickening 
ingredient and various additive agents designed to enhance the lubricant 
with respect to viscosity, foam stability, antiwear, and corrosion 
prevention properties. More recently, current interest has been directed 
to the preparation of aqueous lubricants, particularly water-content 
hydraulic fluids, due to the increasing cost of petroleum oils, the 
problem of flammability and the ever increasing problem of suitable 
disposal of contaminated or spent petroleum-based fluids. Water-content 
hydraulic fluids containing up to 95 percent or more water offer an 
obvious cost advantage over petroleum-based hydraulic fluids but because 
of their viscosity suffer the disadvantage of being susceptible to 
leakage, thereby resulting in loss of volumetric efficiency and markedly 
reducing the service life of hydraulic pumps. Although primarily used for 
transmitting forces, water-content hydraulic fluids must provide 
lubrication for impellers, support bearings, rings, gears, pistons, and 
the like, with a minimum of internal leakage in order to prevent excessive 
wear and failure of such parts. 
It is known from U.S. Pat. No. 4,215,002 to prepare water-content hydraulic 
fluids by adding to water 0.5 to 4 wt.% of a blend of C.sub.6-18 
alkylphosphonate or an amine adduct thereof and an ethoxylate of an acid 
or an alcohol containing from 3 to 20 ethoxy groups wherein the acid or 
alcohol is derived from fatty or synthetic sources. 
U.S. Pat. No. 4,225,447 discloses an emulsifiable concentrate for use in 
water-in-oil fire-resistant hydraulic fluids comprising a lubricant and an 
alkenylsuccinic anhydride or a salt thereof. 
U.S. Pat. No. 4,253,975 discloses an aqueous hydraulic fluid containing a 
metal dithiophosphate and a system of solubilizers therefor. 
It is also known from U.S. Pat. No. 4,289,636 to provide aqueous 
lubricating compositions comprising water and a minor amount of a 
water-soluble amide derived from primary and secondary alkyl amines and 
succinic, tetrahydrophthalic or tetrahydrofuran tetracarboxylic acids. The 
amide is effective as a corrosion or antirust inhibitor. Aqueous lubricant 
formulations containing the amide in combination with other known special 
purpose additives provide a blend having good hard water stability 
characteristics. 
U.S. Pat. Nos. 3,826,745 and 3,838,049 disclose the use of polyisobutylene 
polymers in lubricating compositions for internal combustion engines. 
U.S. Pat. No. 4,212,750 discloses a water-based metal working lubricant 
which may contain at least about 2 parts by weight polyisobutylene. 
The prior art does not disclose the use of polyisobutylene in high 
water-content hydraulic fluids in combination with the 
emulsifier/dispersant and antiwear/antirust inhibitor systems described 
herein. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an improved water-content 
hydraulic fluid having a reduced tendency to leak is prepared by admixing 
a small amount of polyisobutylene polymer with a soluble oil concentrate 
comprising an appropriate base oil blended with certain 
emulsifier/dispersant and antiwear/antirust inhibitor systems. Such 
concentrates, when mixed with a sufficient quantity of water, are capable 
of forming stable, translucent oil-in-water emulsions in which the oil is 
present as the continuous phase. When used as high water-content hydraulic 
fluids, significant improvement is obtained whereby the tendency of the 
fluids to internally leak in hydraulic systems is minimized, thereby 
reducing the loss of volumetric efficiency in hydraulic pumps 
conventionally used for industrial applications. Additionally, the 
water-content hydraulic fluids are excellent lubricants which are 
characterized by improved wear-preventing characteristics and antirust 
performance. 
DETAILED DESCRIPTION OF THE INVENTION 
The polyisobutylene polymers used for purposes of the invention are known 
materials having a mean molecular weight between about 500 and 2000 and 
preferably between 1000 and 1500. These polymers are generally obtained by 
polymerizing C.sub.4 mono-olefins in the presence of a Friedel-Crafts 
catalyst to obtain polymer mixtures containing primarily polyisobutylene 
and polybutylene in varying proportions. Typical polymer mixtures will 
contain about 10 to 80% polyisobutylene and 80 to 20% of polybutylene. It 
is to be understood that either of these polymers may be used since such 
polymers are similar with regard to performance. Further, since the 
polymers contain a terminal group which is unsaturated they may be 
saturated by hydrogenation. 
The polyisobutylene polymer may be added to the concentrate before dilution 
with water. Based on the soluble oil concentrate, the amount of polymer 
employed ranges from 0.001 to 3.0 percent by weight. 
In addition to the polyisobutylene polymer, the soluble oil concentrate 
contains from about 25 to 60 percent by weight of an emulsifier/dispersant 
and about 10 to 20 percent by weight of an antiwear/antirust inhibitor 
system. The balance of the concentrate comprises the base oil and, 
possibly, minor amounts of other additives conventionally employed to 
impart certain properties. Among such additives are defoamers, metal 
deactivators, antibacterial agents, and the like. In practicing the 
invention, the concentrate is simply diluted with distilled or deionized 
water to provide hydraulic fluids consisting of about 80 to 99 weight 
percent water and 0.005 to 20.0 percent concentrate. On the basis of 
results obtained, improvement in flow rates and volumetric efficiency 
losses are achieved when the amount of the total concentrate used is less 
than 5.0% based on the weight of the aqueous hydraulic fluid composition. 
The emulsifier/dispersant systems used for purposes of the invention 
include a wide variety of anionic, cationic and nonionic compounds which 
are well known in the art and have been employed for this purpose. Any 
compatible combination of emulsifying or dispersing agent can be employed. 
Likewise, compounds which possess both emulsifying and dispersing 
properties may be employed alone or in combination with other emulsifiers 
and/or dispersants. The emulsifier/dispersant systems serve to disperse 
the antirust and antiwear additives in the aqueous phase of the 
water-content fluids and hence various combinations are thus possible for 
this purpose. 
Typical anionic emulsifiers suitable for the present invention are amine 
soaps, and the like. Such soaps are prepared by the reaction of an amine 
with a fatty acid such as palmitic acid, lauric acid, oleic acid, myristic 
acid, tall oil acids, palm oil acids, or the like, in about stoichiometric 
amounts at room temperature or slightly elevated temperatures. Examples of 
amine soaps include triethanolamine stearate, triethanolamine oleate, 
triethanolamine coconut oil soap, isopropanolamine oleate, N,N-oleate, and 
the like. 
The cationic emulsifiers contemplated herein are the combination of an 
organic acid, such as cyclic imidazoline, tertiary ethyloxylated soya 
amine, tallow polyethoxylated amine having two ethoxy units in the 
polyethoxylated position of the molecule, oleyl polyethoxylated amines 
having two to five ethoxy units in the polyethoxylated portion of the 
molecule, soya polyethoxylated amine having five ethoxy units in the 
polyethoxylated portion of the molecule, and the like. 
Other emulsifiers include the alkali and alkaline earth metal salts of 
fatty acids, rosin acids and naphthenic acids. Preferred fatty acids are 
the wood, gum and rosin acids derived from crude tall oil and various 
distilled products of tall oil. Tall oil is a byproduct of the sulfate 
industry where it is found in the sulfide liquor that has been used to 
digest wood. The oil is a crude product containing various unsaturated 
fatty acids, chiefly oleic and linoleic, rosin acids and some 
unsaponifiable materials. The crude tall oil can be employed as such in 
the invention, however, more suitably, the metal salts or soaps of various 
refined of distilled products of the crude oil are employed. Examples of 
these are the tall oil distillate that contains only slight amounts of 
rosin acids and from about 75-90% unsaturated fatty acids. Other products 
are distilled tall oil having 25-35% rosin acids and 60-75% fatty acids. 
The tall oil pitch from the distillation has from about 20-25% rosin acids 
and 30-40% unsaturated fatty acids, the balance being unsaponifiable 
material. 
The alkali and alkaline salts of rosin acids are water insoluble and are 
highly useful emulsifiers for purposes of the invention. Additionally, 
they also aid in sealing the tolerances between the moving surfaces of 
hydaulic pumps. 
Other emulsifiers which can be employed are nonionic and include the 
polyalkylene glycol ethers containing from about 4 to about 80 mols of 
alkylene oxide. Illustrative non-ionic emulsifiers are the nonylphenyl 
polyethylene glycol ethers containing about 4 moles of ethylene oxide, the 
trimethylnonyl polyethylene glycol ethers containing about 6 moles 
ethylene oxide, the nonylphenyl polyethylene glycol ethers containing 
about 7 moles of ethylene oxide, mixed polyalkylene glycol ethers 
containing about 60 moles of a mixture of ethylene oxide and 1,2-propylene 
oxide in a mole ratio of about 2:1. The nonionic emulsifiers are well 
known in the art and may be prepared by condensing a 1,2 alkylene oxide, 
preferably ethylene oxide, with an organic compound containing at least 6 
carbon atoms and a reactive hydrogen atom such as alcohols, phenols, 
thiols, primary and secondary amines and carboxylic and sulfonic acids and 
their amides. The amount of alkylene oxide or equivalent condensed with a 
reactive chain will generally depend upon the particular compound 
employed. About 20 and 85 percent by weight of combined alkylene oxide is 
generally obtained in a condensation product, however, the optimum amount 
of alkylene oxide or equivalent utilized will depend upon the desired 
hydro-phobiclipophilic balance desired. 
The preferred dispersant used herein is the reaction product of amine with 
an alkyl or alkenyl succinic acid anhydride. Any alkyl or alkenyl succinic 
acid anhydride or the corresponding acid is utilizable in the present 
invention. The general structural formulae of these compounds are: 
##STR1## 
wherein R is an alkyl or alkenyl radical. When R is alkenyl, the alkenyl 
radical can be straight-chain or branched-chain; and it can be saturated 
at the point of unsaturation by the addition of a substance which adds to 
olefinic double bonds, such as hydrogen, sulfur, bromine, chlorine, or 
iodine. It is obvious, of course, that there must be at least two carbon 
atoms in the alkenyl radical, but there is no real upper limit to the 
number of carbon atoms therein. The alkyl and alkenyl succinic acid 
anhydrides and succinic acids are interchangeable for the purposes of the 
present invention. 
The methods of preparing the alkenyl succinic acid anhydrides are well 
known to those familiar with the art. The most feasible method is by the 
reaction of an olefin with maleic acid anhydride. 
A more detailed description of the alkenyl succinic anhydrides suitable for 
use in the above formulations and their preparation is disclosed in U.S. 
Pat. No. 2,638,450, issued May 12, 1953. 
Any alkyl or alkenyl succinic acid, the alkyl or alkenyl substituent of 
which contains from about 6 to about 22 carbon atoms may be employed for 
reaction with the amine. Typically representative of such alkyl or alkenyl 
succinic acids, are tetrapropenyl-succinic, octenylsuccinic, 
dodecenylsuccinic, polybutenylsuccinic, hexadecenylsuccinic, 
triacontenylsuccinic and isooctadecylsuccinic acids. Especially preferred 
materals are alkenylsuccinic anhydrides wherein the alkenyl radical is 
derived from an olefin containing 2 to 10 carbon atoms and has an average 
molecular weight of from about 300 to 3000, preferably about 900 to about 
1300. 
The alkyl or alkenyl succinic acid anhydrides are reacted with an amine 
such as the aforementioned amines listed for preparation of the cationic 
emulsifiers. The reaction is carried out at temperatures of about 
150.degree. C. to 250.degree. C. and the exact composition of the 
resulting product mixture is extremely complex depending upon whether 
primary amines or tertiary hydroxy amines enter into the reaction. This 
may be illustrated as follows: 
##STR2## 
The neat concentrate will contain about 25 to 60 percent by weight of the 
emulsifier/dispersant system in which the emulsifier is present in an 
amount ranging from 20 to 50 percent by weight or more. 
The antiwear/antirust inhibitor system is present in amounts ranging from 
about 10 to 20 percent by weight based on the weight of the neat 
concentrate. It is contemplated that a wide variety of additives 
conventionally employed to impart antiwear and antirust properties may be 
used. Specifically useful antiwear inhibitors are zinc dialkyl 
dithiophosphates such as zinc di (iso-octyl primary) dithiophosphate, zinc 
di (n-octyl primary) dithiophosphate, zinc butyl hexyl dithiophosphate, 
zinc butyl, 1,2-di methylpropyl dithiophosphate and zinc di (4 
methyl-2-pentyl) dithiophosphate. 
Although the zinc dialkyl dithiophosphates provide antiwear and some 
antirust properties, it has been found desirable to add an additional 
antirust inhibitor to the concentrate such as a metal dialkylnaphthalene 
sulfonate. The metal dialkylnaphthalene sulfonate has a sulfonate group 
attached to one ring of the naphthalene nucleus and an alkyl group 
attached to each ring. Each alkyl group can independently contain from 
about six to about twenty carbon atoms, but it is preferred that they 
contain from about eight to twelve carbon atoms. The dialkylnaphthalene 
sulfonate group is attached to the metal through the sulfonate group. In 
the case of monovalent metals, one dialkylnaphthalene sulfonate group is 
attached to each metal atom while there are two groups attached to each 
atom of a divalent metal. Calcium, barium, sodium, magnesium and lithium 
can be used as the metal, but it is preferred to use calcium as the metal 
in the sulfonate. The metal dialkylnaphthalene sulfonate is used in 
amounts of 30 to 60 percent by weight based on the weight of the combined 
antiwear/antirust inhibitor system. 
The oil vehicles employed in the composition of the present invention may 
comprise mineral oils, synthetic oils, especially synthetic hydrocarbon 
oils, or combinations of mineral oils with synthetic oils of lubricating 
viscosity. When high temperature stability is not a requirement, mineral 
oils having a viscosity of at least 40 SSU at 100.degree. F., and 
particularly those falling within the range from about 60 SSU to about 
6,000 SSU at 100.degree. F. may be employed. In instances where synthetic 
vehicles are employed, either alone or in addition to mineral oils, as the 
lubricating vehicle, various compounds of this type may be successfully 
utilized. Typical synthetic vehicles include polypropylene glycol, 
trimethylopropane esters, neopentyl and pentaerythritol esters, 
di-(2-ethyl hexyl-sebacate, di-(2-ethyl hexyl) adipate, dibutyl phthalate, 
fluorocarbons, silicate esters, silanes, esters of phosphorus-containing 
acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, 
chain-type polyphenols, siloxanes and silicones (poly-siloxanes), 
alkyl-substituted diphenyl ethers typified by a butyl-substituted 
bis-(p-phenoxy phenyl)ether, phenoxy phenyl ethers, and the like. 
The synthetic hydrocarbons which may be used are of the type normally made 
by polymerizing monoolefins in the presence of a suitable catalyst, such 
as BF.sub.3 or AlCl.sub.3. The lower olefins may be employed for the 
purpose provided the degree of polymerization is sufficient. The lower 
olefins include, for example, ethylene, propylene, butylene and the like. 
Those useful in the practice of this invention preferably contain at least 
30 carbon atoms. One such member is made by trimerizing decene. The 
synthetic hydrocarbon, or polyolefin, suitable for use in this invention 
may have an upper limit of about 75 carbon atoms. Such hydrocarbon fluids 
retain their fluidity at the lower temperatures and have enhanced 
resistance to flame and explosion hazards. 
In combination with the aforementioned emulsifier/dispersant and 
antiwear/antirust systems, other additives may be employed to impart 
certain desired properties. An alkali metal nitrite may also be employed 
in the formulation in order to impart increased antirust properties to the 
lubricant composition. In this respect, more specific increased resistance 
to copper corrosion may be obtained by the use of the sodium salt of 
mercaptobenzothioazole. In addition, the overall performance properties of 
the lubricant composition may be enchanced by the addition of germicidal 
agents, particularly phenolic materials such as phenol, sodium salts of 
orthophenylphenol, chlorinated phenols, such as hexachlorophene, 
tetrachlorophenol and p-chloro-m-xylenol, and also boric acid or oxides of 
boron. In order to obtain fungus protection, improve the rust protection 
properties, and also to function as a load-support agent, an alkali metal 
hydroxide, serving to raise the pH of the system, may be employed. These 
may include, for example, sodium, lithium or potassium hydroxide. 
Furthermore, if desired, various water-soluble chelating agents may be 
employed to soften the water vehicle. Thus, for example, the sodium salt 
of diethylene triamine pentaacetic acid or salts of ethylenediamine 
tetraacetic acid or nitrilotriacetic acid can be used. 
The alkali metal nitrite, when included in the final formulation is 
generally employed in an amount from about 0.1 to about 10 percent, and 
preferably from about 0.1 to about 5 percent, by weight. When the sodium 
salt of mercaptobenzothiazole is included in the formulation, this 
material is generally present in an amount from about 0.1 to about 6 
percent, preferably from about 0.1 to about 3 percent, by weight. The 
germicidal agents disclosed above, when present, are generally employed in 
amount from about 0.05 to about 3 percent, and preferably from about 0.05 
to about 1.5 percent, by weight. The water-soluble boron additive, e.g., 
boric acid, when present, is generally employed in an amount from about 
0.1 to about 5 percent, and preferably from about 0.1 to about 3 percent, 
by weight. The alkali metal hydroxide, e.g., sodium hydroxide, is employed 
in an amount from about 0.1 to about 1.5 percent, by weight when present. 
When any of the aforementioned chelating agents or additive agents are 
employed, these are generally present in an amount from about 0.1 to about 
5 percent, by weight. 
The following examples illustrate the best mode now contemplated for 
carrying out the invention.

EXAMPLE 1 
A concentrate which can be added to water to provide high water based 
fluids was prepared according to the following recipe: 
______________________________________ 
Ingredients Parts by Weight 
______________________________________ 
Solvent naphthenic neutral base stock 
40.0 
(100 SUS at 100.degree. F.) 
Zinc dialkyl dithiophosphate 
10.0 
Calcium dinonyl naphthalene sulfonate 
5.0 
Potassium soap of processed rosin.sup.(1) 
20.0 
Polyoxyethylene soyamine 
25.0 
______________________________________ 
.sup.(1) Dresinate 91. Manufactured by Hercules Powder Co. 
EXAMPLE 2 
Two parts by weight of a polyisobutylene polymer having an average 
molecular weight of about 2000 (Lubrizol 3174) were mixed with 98 parts by 
weight of the concentrate of Example 1. 
EXAMPLE 3 
Two parts by weight of a polyisobutylene polymer having an average 
molecular weight of about 1500 (Lubrizol 5183) were mixed with 98 parts by 
weight of the concentrate of Example 1. 
EXAMPLE 4 
One part by weight of a polyisobutylene polymer having an average molecular 
weight of about 1,000,000 was mixed with 99 parts by weight of the 
concentrate of Example 1. 
The compositions of Examples 1 to 4 were admixed with water to provide high 
water base fluids and then evaluated for volumetric efficiency by the 
Vickers V-104C Vane Pump Test (Modified ASTM D-2882). In this test, 
hydraulic fluid is drawn from a closed sump to the intake side of a 
Vickers V-104C vane-type pump. The pump is driven by, and directly coupled 
to, a twenty-five horsepower, 1250 rpm electric motor. The fluid is 
discharged from the pump through a pressure regulating valve. From there 
it passes through a calibrated venturi (used to measure flow rate) and 
back to the sump. Cooling of the fluid is accomplished by a heat exchanger 
through which cold water is circulated. No external heat is required, the 
fluid temperature being raised by the frictional heat resulting from the 
pump's work on the fluid. Excess heat is removed by passing the fluid 
through the heat exchanger prior to return to the sump. The Vickers V-104C 
vane-type pump comprises a cylindrical enclosure (the pump body) in which 
there is housed a so-called "pump cartridge". The "pump cartridge" 
assembly consists of front and rear circular, bronze bushings, a rotor, a 
cam-ring and rectangular vanes. The bushings and cam-ring are supported by 
the body of the pump and the rotor is connected to a shaft which is turned 
by an electric motor. A plurality of removable vanes are inserted into 
slots in the periphery of the rotor. The cam-ring encircles the rotor and 
the rotor and vanes are enclosed by the cam-ring and bushings. The inner 
surface of the cam-ring is cam-shaped. Turning the rotor results in a 
change in displacement of each cavity enclosed by the rotor, the cam-ring, 
two adjacent vanes and the bushings. The body is ported to allow fluid to 
enter and leave the cavity as rotation occurs. 
The test procedure used herein involves circulating 5 gallons of the water 
based fluid through the pump apparatus at a temperature of 
120.+-.3.degree. F. for 100 hours. The pump is run at 1200.+-.60 rpm at a 
pump discharge pressure (load) of 800.+-.15 psi. Flow rate in gallon per 
minute is measured and recorded every four hours. The flow rates reported 
in Table I are averaged over the 100 hours operation. Leakage flow is 
calculated by subtracting average flow rate from a rated flow rate of 7.2 
gpm for this type of pump. Volumetric efficiency loss is defined as: 
##EQU1## 
As shown below in Table I, the use of polyisobutylene polymers provides 
unexpected results in reducing internal leakage in hydraulic pumps, 
thereby increasing flow rate and volumetric pump efficiency. 
TABLE I 
______________________________________ 
FLOW RATE DATA FOR HIGH-WATER-BASE FLUIDS 
Concentrate 5 6 7 8 
______________________________________ 
Example 1 5.0 
Example 2 5.0 
Example 3 5.0 
Example 4 5.0 
Distilled Water 95.0 95.0 95.0 95.0 
Viscosity, cSt at 40.degree. C. 
0.80 0.80 0.79 0.81 
V-104C Vane Pump Test* 
Flow Rate, gpm 3.2 3.6 5.7 4.6 
Leakage Flow, gpm 
4.0 3.6 1.5 2.6 
% Volumetric Eff. Loss 
55.5 50.0 20.8 36.1 
______________________________________ 
*Rated Flow Rate = 7.2 gpm 
Modified ASTM D2882 (800 psi, 120.degree. F., 1200 rpm, 100 h.)