CA1087159A - Silicone hydrocarbon hydraulic fluids - Google Patents

Abstract

SILICONE-HYDROCARBON HYDRAULIC FLUIDS
ABSTRACT
Hydraulic fluid compositions comprising an akloxysiloxane and a hydrocarbon oil.

S P E C I F I C A T I O N
++

1.

Description

BACKGROUND OF THE INVENTION
This invention is directed to hydraulic fluids and more particularly to silicone-hydrocarbon hydraulic fluids which may be used in various hydraulic systems where extremes of temperatures are encountered such as in aircraft and automotive hydraulic systems, especially brake systems.
Hydraulic fluids having good viscosity-tempera-ture, viscosity-volatility and stability characteristics are very desirable. For instance, hydraulic fluids should in the broadest sense have viscosities high enough to satisfy the hydrodynamic requirements of the hydraulic pump and other eleme~ts of the hydraulic loop at the upper temperature extreme experienced and yet be low enough to flow freely at the lowest temperature ex-pected. Attempts to attain such hydraulic fluids by the use of organosilicone materials have in general not proven particularly satisfactory. By way of illustration, silicone oils [i.e. materials having the formula Me3Si0(Me2Si0)xSiMe3]
are not readily compatible with the elastomers ordinarily used in hydraulic systems. For instance, they tend to shrink SBR rubber gaskets often present in hydraulic systems which results in leakage o~ the silicone oil from the system. Silicone oils also have relatively poor lubricity for the metals conventionally used in hydraulic systems and hence relatively high wear is encountered when silicone oils are employed in such systems.

1~7il59 106~70 The use of liquid alkoxysiloxanes such as disclosed in Canadian Patent No. 1,052,805 has been found to improve rubber swell of styrene butadiene rubber (SBR).
Moreover, mixtures of such types of alkoxysiloxanes along with a glycol ether phosphoric acid ester are taught to be useful as hydraulic fluids having an excellent water tolerance at -40C in U.S. Patent No. 3,974,080. However, .
such alkoxysiloxanes when employed alone have a tendency to cause shrinking and cracking of polychloroprene rubber which is commonly employed as the hose in brake systems and such shrinkage and cracking could lead to rupture of the brake hose and failure of the brake system.
It has been discovered that such drawbacks may be overcome or at least minimized by the hydraulic fluids compositions of this invention which comprise an alkoxysiloxane and a hydrocarbon oil.
SUMMARY OF THE INVENTION
-Therefore it is an object of this invention to provide novel hydraulic fluid compositions comprising an alkoxysiloxa.ne and a hydrocarbon oil. It is another object of this invention to provide a novel process that employs said hydraulic fluid compositions in a hydraulic system. Other objects and advantages of this invention will become readily apparent from the following description and appended claims.
More particularly this invention may be described as a hydraulic fluid composition consisting essentially of 1~71S9 (A) about 50 to about 99% by weight of an alkoxysiloxane having the formula RO[(cH3)2sio]nR
wherein R is a monovalent hydrocarbon group or a mixture of monovalent hydrocarbon groups, derived from an aliphatic alcohol or a mixture of aliphatic alcohols respectively, having the formula ROH by removal of the hydroxyl group, said alcohol or mixture of alcohols having a boiling point above about 78C at atmospheric pressure and wherein n is an integer having a value of about 5 to about 200; and (B) about 1 to about 50 percent by weight of a hydrocarbon oil selected from the class consisting of naphthenic oils, alkylated aromatic oils, and branched chain aliphatic hydrocarbon oils.
DESCRIPTION_OF THE PREFERRED EMBODIMENT
The alkoxy siloxanes employed in this invention as well as methods for their preparation are fully disclosed in Canadian Patent No. 1,052,805 and U.S. Patent No. 3.974,080. For instance the alkoxy siloxanes can be prepared by reacting a dimethylsiloxane hydrolyzate with a suitable alcohol or mixture of alcohols in the presence of a basic catalyst (e.g., potassium hydroxide) and aromatic solvent (e.g., xylene) at an elevated temperature (e.g. 9 from 100 to 150C). The dimethysiloxane hydrolyzate employed in producing the alkoxysiloxanes of this invention can be . ~A .

prepared by the hydrolysis of dimethyldichlorosilane in the presence of hydrochloric acid by conventional techniques.
The hydrolyzate so produced consists of a mixture of cyclic dimethylsiloxanes and linear hydroxyl end-blocked dimethylsiloxanes. The alcohol reactants used in pro-ducing alkoxysiloxane for this invention are commercially available or can be prepared by a 2-step process. The first step is the oxo or hydroformylation reaction of olefins with carbon monoxide and hydrogen in the presence of a catalyst to produce an aldehyde intermediate. The second step is the hydrogenation of the intermediate to produce the alcohol. This 2-step process produces mixtures of alcohol (e.g., mixtures of isomeric isodecanols and mixtures of isomeric tridecanols). Alternatively, suitable alcohols can be produced by other processes that provide individual alcohols, e.g., ethanol, isopropanol, isobutanol, 3-methyl-1-butanol, 2-ethylhexanol, and the like. The alcohols have from 2 to 18 carbon atoms and preferably from lO to 14 carbon atoms.
The alkoxysiloxanes described above may be employed in the hydraulic fluids of this invention as such, i.e. stripped of all unreacted alcohols, or they may contain a minor amount of unreacted alcohols. For example, mixtures containing from 70 to ~8 parts by weight of the alkoxysiloxane and from 30 to 2 parts by weight of unreacted alcohol per 100 parts by weight of the alkoxysiloxane-alcohol mixture may be employed.
Generally it is preferred that such mixtures contain less than about 5 parts by weight of unreacted alcohol while the use of alkoxy-siloxanes stripped of all unreacted alcohols is most preferred.

Naphthenic oils that can be employed in this irlvention are refined petroleum distillate fractions containing large proportions of naphthene ring carbons, i.e. 30-45%
Cnaphthene. Ge~rally they will have aniline points ranging from about 135F to L85F indicating a significant number of aromatic carbon atoms, i.e. about 10 to 30%
CarOmatic Such naphthenic petroleum oil fractions are well known in the art and are normally obtained by the conventional refining of fossil or synthetic crude oils, e.g. United States Southwest and Coastal naphthenic crudes, by atmospheric and/or vacuum distillation followed hy solvent and/or hydrogen refining and solvent or low temperature solution dewaxing, if desired. Illustrative of the more preferred naphthenic oils that can be employed herein are those commercial oils like "Calumet" of the Calumet Refining Company, "Circosol' of Sun Oil Co., and "Necton" oils of the Exxon Company, and the like.
Alkylated aromatic oils that can be employed in this invention are synthesized aromatic hydrocarbon oils. Such alkylated aromatic oils are well known and are normally obtained by the alkylation of selected aromatic intermediates, e.g. by conventional alkylation via the well known Friedel-Crafts reaction. Illustrative alkylation agents are alphaole~ins, chlorinated alkanes, alcohols, and the like having up to about 24 carbon atoms. Illustrative aromatic intermediates are benzene, alkyl-substituted benzenes, e.g. toluene, xylene, propyl substituted benzenes, butyl substituted benzenes, a4~ s 6.

di-lauryl benzene, di-(mixed Cll to C15 alkyl) benzenes, bis-(di-tert butyl phenyl) methane, bis-(di-tert butyl phenyl) ethane, bis-(di-tert butyl phenyl)isopropane, and the like, as weLl as a aromatic mixture residues obtained in the commercial production of detergent alkylates. Other illustrative aromatic intarmediates are naphthalene and various alkyl substituted naphthalenes wherein the alkyl group contains from 1 to 4 carbon atoms, e.g. methyl naphthalene, di- and tripropylnaphthalene, di-, tri- and tert-butyl naphthalenes, and the like, as well as the mixed naphthalene-methyl naphthalene refinery streams obtained in commercial pyrolysis processes for the manufacture of ethylene, propylene, acetylene, and the like. Illustrative of the more preferred alkylated aromatic oils that can be employed in this invention are hydrogenated and unhydrogenated propyl substituted naphthalenes such as commercial oils like "Kureha" of the Kureha Chemical Industry Company and more preferably mixed butylated methylnaphthalenes obtained by reacting the mixed naphthalene-methylnaphthalene refinery streams referred to above with isobutylene using a Friedel-Crafts type catalyst, such as "Panaflex~
; BN-l" of the Amoco Chemical Company. For example, it is believed that "Panaflex BN-l" is a mixture of about 44 weight percent of di-butylmethylnaphthalenes, about 28 weight percent of methyltributylnaphthalene, about 15 weight percent of butylmethylnaphthalenes, 10 weight percent of butyldimethylnaphthalenes, and about

2 weight percent of various isomeric butylnaphthalenes.

7.

The branched-chain aliphatic hydrocarbon oils that can be employed in this invention are well known alkylates boiling in the preferred range of about 400F to 700F. Such branched-chain hydrocarbon oils are those wherein the branch chains contain one to two carbon atoms, preferably one carbon atom and are commonly known as isoparaffinic oils. They can be produced by the conv~ntional processes of alkylating C2 to C5 olefins with isoparaffins containing a tertiary carbon atom and having 3 to 6 carbon atoms such as isobutane. They may also be prepared by the polymerization of selected olefins such as C2 to C4mono-olefins.
Polymerization conditions, i.e. temperature, pressure and catalyst, are selected so as to optimize the branching of the polymer chain to achieve good viscosity-temperature properties, while at the same time providing low pour points and good low temperature flow characteristics.
Illustrative examples of such branched-chain hydrocarbon oils are polypropylene, C18 to C21 carbon atoms;
polyisob~tylene, C12 to ~ C40 carbon atoms, mol. wt. about 600 ("Oppanol B-l of Badische Anilin und Soda-Fabrik, AG.);
the polyisobutylene residue after stripping material boiling from 55C. to 128C. at 1 mm. pressure from said "Oppanol B-l"; and the like, as well as 2, 2, 4, 4, 6, 8, 8-heptamethylnonane; 2, 6, 10, 14-tetramethylpentadecane, and the like. The most readily available source of branched-chain hydrocarbon oils that can be employed in this invention are mixed isoparaffin-naphthene hydrocarbon stocks obtained by the appropriate 8.

refining of petroleum fractions boiling within the range of about 400F to 700F at atmospheric pressure, i.e.
those obtained from the so-called gas-oil refining streams. Suitable refining normally includes the steps of (a) preliminary chemical treatment such as caustic scrubbing followed by acid neutralization and wax removal by conventional means, if necessary, (b) selective dearomatization by treatment with sulfuric acid or a catalytic hydrogen treatment and (c) filtering using an ordinary clay-type filter media. Illustrative of the more preferred branched-chain hydrocarbon oils that can be employed by this invention are commercial iso-paraffinic oils such as "Exxon 3146" and "Exxon~3147" of the Exxon Company, U.S.A. It should be pointed out that oils of this type are not exclusively isoparaffinic, i.e.
they contain substantial quantities of naphthenic rings and in some cases, minor proportions of aromatic rings.
It is known, however, that isoparaffinic hydrocarbon mixtures with relatively small proportions of cyclic structures can be ~ade by the separation of the branched chain or iSoparaffinic portions of mixed branched chain/
straight chain hydrocarbon mixtures as e.g. the hydrocarbon fraction of conventional petroleum kerosene fractions.
Such separations may be made by the use of selected zeolite clays, e.g. Molecular Sieve 5A produced by the Linde Division of Union Carbide Corporation. Advantage may also be taken of the ability of n-paraffins to form a~dition products with urea or thiourea to effect the separation of branched chain and straight chain aliphatic hydrocarbons.

~ f~dc ~
g.

~fl7~59 The more preferred hydrocarbon oils employed in this invention may be characterized by their Sabolt seconds universal viscosity at 100F., (Ssu), while the naphthenic oils may be further characterized by their VGC
(viscosity-gravity constant). The Sabolt seconds universal viscosity is measured by ASTM test method D88-56. The VGC concept for the characterization of petroleum lubricating oils was first published by J. B. Hill and H. B. Coats in "The Viscosity-Gravity Constant of Petroleum Lubricating Oils" Industrial and Engineering Chemistry, June 1968, P 641 and is now widely accepted procedure for the approximation of the degree of aromaticity or paraffinicity of a hydrocarbon. The viscosity-gravity constant employed herein is determined by ASTM test method D-2501-67 published in the 1973 Book of the A~erican Society for Testing and Materials, Part 18. The VGC is relatively insensitive to molecular weight and is related to the proportion of naphthenic and aromatic structure in the oil. Values of VGC near 0.~00 indicate a paraffinic character, where values close to 1.00 indicate a preponderance of aromatic structures. Preferably all three types of hydrocarbon oils of this invention have a Sabolt seconds universal viscosity at 100F of from 30 to 500 while the naphthenic oils also have a viscosity~gravity constant of at least 0.84.

10 .

1~871S9 Of course, it is understood that the compositions of this invention encompass employing a single type of the above three defined types of suitable hydrocarbon oils (i.e. naphthenic oils, alkylated aromatic oils and branched-chain aliphatic hydrocarbon oils), employing a mixture of two or more different oils, but of the same type (e.g. two different naphthenic oils, and the like) as well as employing a mixture of two or more different types of oils (e.g. a naphthenic oil and an alkylated aromatic oil, and the like). Generally it is preferred to employ a single type of hydrocarbon oil in a given composition, the naphthenic oils being the most preferred.
The silicone-hydrocarbon com?ositions of matter of this invention can be prepared in any conventional manner. Generally the two liquids need only be mixed together in the proportions desired while stirring at room temperature or slightly elevated temperatures.
The proportions of alkoxysiloxane to hydrocarbon oil by ~eight in the compositions of matter of this invention can range from about 50 to about 99 percent by weight of alkoxysiloxane to about 50 to 1 percent by weight of hydrocarbon oil and more preferably from about 90 to about 95 percent by weight of alkoxysilo~sne and 10 to about 5 percent by weight of hydrocarbon oil.
The hydrocarbon oils employed herein have been found to be miscible at about room temperature for at least 72 hours with the alkoxysiloxanes employed herein.

11 .

lQ87159 The more preferred hydraulic fluid compositions are those wherein the alkoxysiloxane and hydrocarbon oil are selected such that said alkoxysiloxane and hydrocarbon oil remain miscible with each other at about -40F. for at least 72 hours, since such compositions are especially useful as brake fluids. The term "miscible" is used herein to mean that there is no development of either separation or precipitation observed in the composition containing on~y the alkoxysiloxane and hydrocarbon oil during the prescribed storage period.
Moreover, the hydraulic fluid compositions of this invention have been found to improve the volu~e swell rating of polychloroprene rubber over that obtained by the use of the alkoxysiloxane polymer alone. This improvement is especially meaningful in the brake fluid art, since polychloroprene rubber is often employed as the inner core of the hose in brake ; systems. An insufficient volume swell rating is an indication that the brake fluid can cause unacceptable shrin~age and cracking of the polychloroprene rubber hose. It is considered that this problem of shrinkage and cracking of the polycloroprene rubber hose can be overcome or at least greatly minimized by the hydraulic fluid compositions of this invention. Thus, the most preferred hydraulic fluid compositions of this invention are those wherein a mixture of the alkoxysiloxane and the hydrocarbon oil in the same proportions as present in the hydraulic fluid composition has a volume swell rating of polychloroprene rubber of from -3 to +20 percent.

- 1~871S9 Of course, it is to be understood that not every possible hydrocarbon oil employable herein ma1y be miscible to the same degree and/or may improve the volume swell of polychloroprene rubber to the sa~e degree with every possible alkoxysiloxane employable herein. Likewise it is to be understood that not every possible proportionate range by volume employable herein for every alkoxysiloxane and hydrocarbon oil com-ponent of this invention may give the same degree of results. However, said Ssu viscosity and VGC values may help serve as a general guideline to generically determine whether or not a particular hydrocarbon oil is suitable for use in the instant invention. In any event, the determination of same is well within the knowledge of one skilled in the art and can be readily determined by routine experimentation as taught herein.
The alkoxysiloxane-hydrocarbon oil compositions of matter of this invention have good viscosity-temperatures, viscosity-volatility and stability characteristics. They may be employed as hydraulic fluids for conventional hydraulic equipment systems and especially as brake fluids in automotive brake systems.
Accordingly, another aspect of this invention is a process for transmitting force in a hydraulic system which comprises effecting movement of a movable member within an enclosing chamber consisting of transmitting pressure to the movable member through a liquid medium comprising an alkoxysiloxane-hydrocarbon oil composition of matter of this invention as defined above.

~087159 More particularly another aspect of this invention is a process for transmitting force in a hydraulic brake system of a vehicle having activating means, activated means, master brake cylinder means, and hydraulic line means connecting said activating means, said activated means and said master brake cylinder means. This process comprises applying mechanical force to said activating means wherein said activating means, said activated means, said master brake cylinder means, and said hydraulic line means are substantially filled with the hydraulic fluid composition of matter of this invention described above.
Of course, it is to be understood that the specific type of hydraulic system or brake system is not critical and need not be described herein.
Such systems are conventional and well known and the purpose of the present invention is not to define any particular novel mechanical system but to describe novel compositions of matter that are useful as hydraulic fluids, especially automotive brake fluids.
It is to be further understood that the hydraulic fluid compositions of this invention may, if desired, contain other conventional additives in the conventional used quantities commonly employed in hydraulic fluids and brake fluids, such as antioxidants, rust and corrosion inhibitors, anti-wear agen~, dispersants, and the like.

14.

~087~59 The following examples illustrate the present invention and are not to be regarded as limitative. All parts, percentages and proportions referred to herein ~md the claims are by weight unless otherwise otherwise indicated.
As set forth herein below and in the Examples the followin~ abbreviations are used:
Abbreviation Meaning AP Aniline Point as measured by ASTM D611-64.
API. Gr. American Petroleum Institute Gravity as measured by ASTM
D-287-64.
ASTM American Society for Testing and Materials C degree centigrade cm. centimeters cstks. centistokes F degree Fahrenheit ml. milliliters mg. milligram mol. wt. molecular weight SAE Society of Automotive Engineers SBR styrene-butadiene rubber Sp. Gr. specific gravity Ssu. Saybolt Seconds Universal viscosity as measured by ASTM D88-56.
SP Solubility parameter which is equal to VGC/AP X10-3 VGC Viscosity Gravity Constant as measured by ASTM D-2501-67.
wt. weight % percent In the average formulas of the alkoxysiloxane compounds given in the following Examples, "C13H27"
represents a mixture of isomeric tridecyl groups derived by the removal of the hydroxyl groups in the tridecanol mixture of alcohols used as the starting material in the production of said alkoxysiloxanes. This starting material is a mixture of alcohols produced by the con-ventional oxo and reduction processes. The mixture of alcohols consists of about 5% by weight of Cll alcohols, 20 percent by weight of Cl2 alcohols, 64% by weight of C13 alcohols and 10% by weight of Cl4 alcohols. The alcohol mixture has a boiling point of 257.6 degrees . at atmospheric pressure and a pour point of -40C.
Test Procedures In the Examples appearing below, the following test procedures were used.
SAE J 1703 Tests S~R Rubber Swell Test- ~wo brake cylinder cups ~ade of SBR rubber are immersed in 75 milliliters of the fluid being tested and the fluid are then heated for 70 hours at 248F. The average diameter of the two cups are measured before and after the test. The fluid is considered to have passed this test if the change in average cup dia~eter is between 0.006 and 0.055 inch.
Stroke Test- The fluid being tested is used as the hydraulic fluid in a brake system operated at 1000 strokes per hour at 2~8F for a total of ~5,000 strokes at 1000 pounds psi. and the various measurements listed in Table I below are made. The fluid is rated as "sati~factory"
or "unsatisfactory" depending upon its overall performance based on these measurements, 16.

., Corrosion Test - Specimens of various metals are i~mersed in the fluid after the fluid has been subjected t:o a humid atmosphere (80% relative humidity at room temperature ~or 65 hours) The fluid is then maintained at 100C for five days. The specimens are weighed before and after the test and the weight loss of the specimens in milligrams per centimeter is calculated. The fluid is considered to have passed this test when the appearance of the metals is not pitted and when the weight loss of the metals does not exceed the indicated values:
Maximum Weight Loss - Metal (mglcm2,) Cast Iron 0.2 Steel 0.2 Brass 0.4 Copper 0.4 Tin 0.2 Aluminum 0.1 Viscosity- The viscosity of the fluid being tested is measured at 210F and -40F. This fluid is considered to have passed this test when its viscosity is at least 1.5 centistokes at 210F and no greater than 1800 centistokes at -40F.
Other_Tests PolychloroPrene Rubber Volume Swell Test - A one-inch square test specimen of neoprene rubber (SAE Part No.
RN-68) is immersed in 75 milliliters of the fluid being tested.
The fluid is then heated for 70 hours at 212F. The volume swell of the rubber is calculated as follows:

17.

lO 8 71 S9 10680 Volume Swell = A-B x 100 w~Lerein A is the difference between the weight of the specimen in air and the weight of the specimen in water after the test and B is the difference before the test. The fluid is considered to have passed this test when the volume swell is between -3 and +20%.
PolychloroPrene Hose Test - A neoprene rubber hose is immersed in 250 milliliters of the fluid being tested and them the fluid is maintained at 100C for 70 hours.
The fluid is drained and the hose is maintained at -40F
for 24 hours. The hose is then bent around a 3.0 inch mandrel and is inspected for any signs of cracking.
Miscibility Test - A sample blend of the hydraulic fluid composition is stored at a prescribed temperature for a period of time and then observed for the development of separation and precipitation. If neither of these phenomena are observed then the hydrocarbon oil is considered to be miscible in the alkoxysiloxane.
If either of these phenomena are observed, the hydrocarbon oil is considered to be immiscible in the alkoxysiloxane.
The hydrocarbon oils employed int the following Examples were as follows:
"Calumet 5400", a naphthenic oil product of the Calumet Refining Company, having an API Gr.(60/60F.) of of 28.0,'a Sp. Gr. (60/60F.) of 0.8871, a Ssu viscosity at 100F of 54, a AP of 162F., a VGC of 0.8613 and a SP of 5.32.
"Circo Light RPO" a naphthenic oil product of the Sun Oil Company, ha~ing an API Gr. (609/60F) of 22.4 a Sp. Gr. (60/60F.) of 0.9194, a Ssu. viscosity 18.

7'1Sg at 100F. of 156, a AP of 163F., a VGC of 0.8786 and a SP of 5.39.
"Circoso ~450" a naphthenic oil product of the Sun Oil Company, having an API Gr. (60/60F.) of 19.6, a SpO Gr. (60/60F.) of 0.9365, a Ssu viscosity of 100F and 515, an AP of 162., a VGC
of 0.8858 and a SP of 5.46.
"Panaflex BN-l" an alkylated aromatic oil product of Amoco Company having an API GrO (60/60F.) of 0.9465, a Ssu viscosity at 100Fo of 23.0 a AP
of 15F., and a VGC of 009086.
A polypropylene, C18 to C21 carbon atoms, having a Ssu. viscosity at 100F of 32.70 and a Sp. Gr.
(60/60F.) of 0O774.
"Oppanol~B-1" a polyisobutylene, C12 to ~C40 carbon atoms, product of Badische Anilin und Soda-Fabrik, AG. having a Ssu viscosity at 100F. of 69.42, a Sp. Gr. (60/60F.) of 0O825 and a VGC of 0.781.
2J2,4,4,6,8,8-heptamethylnonane having a Ssu viscosity at 100Fo of 36.8 and a Sp. Gr. (60/60F.) of 0.798.
EX~PLE 1 A hydraulic fluid composition consisting of a blend of about 93 percent by weight of an alkoxysiloxane and about 7 percent by weight of Calumet 5400 was prepared.
The alkoxysiloxane was a tridecyloxysiloxane product having the average formula C13H270[(CH3)2Si0]11 sC13 H27 prepared according to the process described in Example I in Canadian Patent No. 1,052,805. Said tridecyloxysiloxane product had a viscosity at 100F of 22.9 ctks. and at 210F
of 8.0 ctks; and contained 3.3% unreacted hydrolyzate cyclics and 7.4% unreacted ~,¢ r~.L~

B~ ~

~ ~G187159 alcohol. The properties of this hydraulic fluid composition are as follows:
Bailing Point, F. 600 S~R Rubber Swell 0.047 inches Viscosity at:
210F 7.9 centistokes -40F. 450 centistokes Stroke Test Satisfactory Corrosion Test Appear~nce (wt. loss, mg./cm') Cast Iron Bright (+0.08) Steel Bright (0.0) Brass Slight Stain (0.11) Copper Bright (0.05) Tin Bright (0.0) Aluminum Bright (0.0) Polychloroprene Rubber Volume Swell, percent -2.79 Polychloroprene Hose Test Satisfactory Miscibility Test (100 ml.
Blends) 6 hours at -60F. Miscible (Clear) 6 days at -40F. Miscible (Clear) By way of comparison the use of 100 percent by weight of the same tridecyloxysiloxane product alone with-out any hydrocarbon oil gave a volume swell of polychloroprene rubber of about -8.97 percent.

A series of hydraulic fluid compositions was prepared by blending a tridecyloxysiloxane product tsame product as described in EXAMPLE 1 above) with Circo Light RP0 ] as the hydrocarbon oil.

, 20.

~0871S9 Blend A was a mixture of about 95 percent by weight o the tridecyloxysiloxane ~nd about 5 percent by weight o:E Circo Light RP0.
Blend B was a mixture of about 93 percent by weight of the tridecyloxysiloxane and about 7 percent by weight of Circo Light RPO.
Blend C was a mixture of about 90 percent by weight of the tridecyloxysiloxane and about 10 percent by weight of Circo Light RPO.
SBR and polychloroprene rubber swell tests were run on said blends according to the testing procedure described above and the results were as follows.
Blend Blend Blend A B C
SBR Rubber Swell (inches) 0.042 0.058 0.068 Polychloroprene Rubber Yolume Swell, percent -2.71 -0.87 +1.65 A hydraulic fluid composition consisting of a 25 milliliter blend of about 50 percent by volume (about 49.5% by weight) of an alkoxysiloxane and about 50 percent by volume (a~out 50.5% by weight) of Circosol 450 was prepared. The alkoxysiloxane was a 50:'50 percent by weight mixture of (l) a tridecyloxysiloxane product having the average formula C13H270[(CH3)2siO]nC13H27~ which a viscosity at 100F of 22.6 cstks. and 7.7 cstks. at 210F., and contained 6.2% unreacted hydrolyzate cyclics and 10.4%
unreacted alcohol and (2) a tridecyloxysiloxane product having the average formula C13H27[(CH3)2Si~]nC13H27~

~87~59 which had a viscosity at 100F of 25.4 cstks. and 8.8 cstks. at 210F, and contained 7.2% unreacted hydrolyzate cyclics and 14.3% unreacted alcohol.
Miscibility tests were run on said hydraulic fluid blend according to the testing procedure described above and the results were as follows.
Room Temperature 72 Hours 0F. 72 Hours -40F. 72 Hours Miscible Miscible Immiscible A hydraulic fluid composition consisting of a 10 ml. blend of about 50 percent by weight of an alkoxysiloxane and about 50 percent by weight of Circosol 450 was prepared.
The alkoxysiloxane was a tridecyloxysiloxane product having the average formula C13~27 E (CH3)2siO]ncl3H27 .
which had a pH of 6.1 in a 50%-50% water-isopropanol mixtureat 10% concentration, a viscosity at 100F of 16.6 cstks.
and 6.1 cstks. at 210F, no detectable unreacted hydrolyzate cyclics and only a trace (~ 0.1%) of unreacted alcohol.
Said hydraulic fluid composition was found to be miscible (clear) after storage for 72 hours at -40F.

A series of hydraulic fluid compositions (hereinafter referred to Blends D to G) were prepared by blending various branched chain aliphatic hydrocarbon oils with a tridecyloxysiloxane product (same product as described in EXAMPLE 4 above).
Blends D and F each contained 90 percent by weight of said tridecyloxysiloxane and 10% by w~ight o the hydrocarbon o:il. Blends E and G each contained 80 percent by weight of said tridecyloxysiloxane and 20 percent by weight of the hydrocarbon oil.
The hydrocarbon oil of Blends D and F was a polypropylene, C18-C21 carbon atoms, having a Ssu. viscosity at 100F of 32.70 and a Sp. Gr. (60/60F.) of 0.774.
The hydrocarbon oil of Blends E and G was Oppanol B~l.
Polychloroprene rubber volume swell tests were then run on each blend according to the testing procedure described above and the results were as follows.
Blend D Blend E Blend F Blend G
Polychloro- ....... __ prene Rubber Volume Swell, percent -7.2 -5.6 -8.1 -6.8 A-hydraulic f7uid composition (hereinafter referred to as Blend H) consisting of 70 percent by volume (about 72%
by weight) of alkoxysiloxane and 30 percent by volume (about 28%
by weight) of 2,2,4,4,6,8,8-heptamethylnonane having a Ssu. viscosity at 100F. of 36.8 and a Sp. Gr. (60/60F.) of 0.798 and a hydraulic fluid composition (hereinafter referred to as Blend I) consisting of 70 percent by volume (about 72% by weight) of an alkoxysiloxane and 30 percent by volume (about 28% by weight) of "Oppanol B-l"
were prepared by blending the two components together.
The alkoxysiloxane in each blend was a tridecyloxysiloxane product having the average formula C13H270[(CH3) Si0] C13H27 which had a pH of 7.0 in a 50%-50% water-isopropanol mix-ture at 10% concentration, a viscosity at 100F. of 17.5 cstks.
and 6.08 cstks. at 210F., no detectable unreacted hydrolyzate cyclics and only 0.2% unreacted alcohol.

108715g Each blend was a 15 ml. mixture and miscibility tests were then run on said two blends according to the testing procedure described above and the results were as follows.
Blend H Blend I
Room Temperature (72 Hours) Miscible Miscible 0F. (72 Hours) Miscible Miscible (Slightly Hazy) -40F. (72 Hours) Miscible Miscible (Slightly Hazy) A hydraulic fluid composition consisting of a 100 ml. blend of 70 per.c~nt by weight of a tridecyloxysiloxane product (same product as described in EXAMPLE 4 above) and 30 percent by weight of Panaflex BN-l was prepared.
Said blend was found to be miscible (clear) after storage for 72 hours at -40F.
Various modifications ~nd variations of this invention will be obvious to a worker skilled in the art and it is to be~:understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the appended claims.

24.

Claims (16)

WHAT IS CLAIMED IS:

1. A hydraulic fluid composition consisting essentially of (A) about 50 to 99 percent by weight of an alkoxysiloxane having the formula:
RO[(CH3)2SiO]nR
wherein R is a monovalent hydrocarbon group or a mixture of monovalent hydrocarbon groups derived from an aliphatic alcohol or a mixture of aliphatic alcohols respectively, having the formula ROH, by removal of the hydroxyl group, said alcohol or mixture of alcohols having a boiling point above about 78°C. at atmospheric pressure, and n is an integer having values of about 5 to about 200; and (B) about 1 to 50 percent by weight of a hydrocarbon oil having a Sabolt seconds universal viscosity at 100°F of from 30 to 500, selected from the class consisting of naphthenic oils having viscosity gravity constants of at least 0.84, alkylate aromatic oils, and branched chain aliphatic hydrocarbon oils wherein the branch chains contain one to two carbon atoms,

2. A composition as defined in claim 1 con-sisting essentially of about 90 to 95 percent by weight of component (A) and about 10 to about 5 percent by weight of component (B) wherein the value of n in component (A) is about 10 to 50 inclusive and wherein R contains about 2 to about 18 carbon atoms.

25.

3. A composition as defined in claim 2 wherein R contains about 10 to about 14 carbon atoms.

4. A composition as defined in claim 1 wherein the properties of (A) and (B) are selected such that said components (A) and (B) remain miscible with each other at about room temperature for at least 72 hours.

5. A composition as defined in claim 1 wherein the proportions of (A) and (B) are selected such that said components (A) and (B) remain miscible with each other at about-40°F. for at least 72 hours.

6. A composition as defined in claim 1, said composition having a volume swell rating of polychloroprene rubber of from -3 to +20 percent.

7. A composition as defined in claim 2 wherein the hydrocarbon oil (B) is a naphthenic oil.

8. A composition as defind in claim 2 wherein the hydrocarbon oil (B) is an alkylated aromatic oil.

9. A composition as defined in claim 2 wherein the hydrocarbon oil (B) is a branched chain aliphatic hydrocarbon oil wherein the branch chains contain one to two carbon atoms.

10. A composition as defined in claim 9, wherein the branch chains of said aliphatic hydrocarbon oil contain one carbon atom.

26.

11. A composition as defined in claim 7, wherein R contains about 10 to 14 carbon atoms.

12. A composition as defined in claim 11, wherein the proportions of (A) and (B) are selected such that said components (A) and (B) remain miscible with each other at about -40°F. for at least 72 hours and wherein said composition has a volume swell rating of polychloroprene rubber of from -3 to +20 percent.

13. A composition as defined in claim 12, wherein R is derived from a mixture of isomeric tridecanols.

14. A composition as defined in claim 1, wherein the alkoxysiloxane is mixed with a minor amount of an alcohol or mixture of alcohols as defined in claim 1.

15. A process for transmitting force in a hydraulic brake system of a vehicle having activating means, activated means, master brake cylinder means, and hydraulic line means connecting said activating means, said artivated means and said master brake cylinder means, comprising applying mechanical force to said activating means, wherein said activating means, said activated means, said master brake cylinder means and said hydraulic line means are substantially filled with an hydraulic fluid composition as defined in claim 1.

16. A process as defined-in claim 15, wherein the hydraulic fluid is a composition as defined in claim 13.

27.