IL26711A - Synergistic functional fluid compositions - Google Patents

Description

C O H E N Z E D E K & S P I S B A C H E G D . P A T E N T A TT O R N E YS 24, LEVONTIN STR., P. O. B. 1109 T E L - AV I V P A T E N T S & D E S I G N S O R D I N A N C E 15842/66 SPECIFICATION SYJffEBSISTIC FUNCTIOHAL FLUID COMPOSITIOKS MONSANTO COMPANY, a corpora ion of the State of Delaware, o 800 Borth lindbergh Boulevard, St. Louis, Missouri 63166, U.S.A.,.

HEREBY DECLARE the nature of this invention and in what manner the same is to be performed to be particularly described and ascertained in and by the following statement: This invention relates to functional fluid composl-• tions composed of petroleum bright stock oil, phosphate ester and halogenated biphenyl and having a unique combination of lubricity, ire-resistance and homogeneity.

Many different types of materials are utilized as functional fluids and functional fluids are used in many different .types bf applications. Such fluids have been used as "electronic coolants, atomic reactor coolants, diffusion pump fluids, synthetic lubricants, damping fluids, bases for greases, force 'transmission fluids (hydraulic fluids) and as ' filter mediums .for air conditioning systems. Because of the · wide variety of applications and the varied conditions under which functional fluids are utilized, the properties desired in a good functional fluid necessarily vary with the particular application in which it is to be utilized with each individual application requiring a functional fluid having a specific .'class of properties. - Of the foregoing the use of functional fluids as lubricants and hydraulic fluids, particularly industrial lubri- cants and hydraulic fluids, has posed a difficult area of application. Increasing demands to improve the safety of indus- ■ trial' manufacturing as a whole has caused the extended use of fire-resistant fluids, e.g. fire-resistant lubricants and fire- resistant hydraulic fluids in a wide range of industries. The ' term "fire-resistant fluid" as used herein means a fluid of such chemical composition and physical characteristics that it will resist the propagation of flame under certain condi emulsions and completely synthetic types. It Is well known In the art that the ability of a fluid to resist flame propagation is one of degree. Fluids of the four types mentioned have varying degrees of fire-resistance and are used in applications according to the severity of the conditions, taking into, account such factors as degree of danger from fire, operating temperature, bearing loads and cost. Many synthetic fluids such as . the aryl phosphate esters offer a high degree of fire resistance and are usually employed when the danger from fire is great. ■The cost of synthetic fluids has restricted their use to the , most severe conditions. The water containing fluids, while a offering an acceptible degree of fire resistance at low cost, are not desirable in systems operating at high temperatures or where good lubricity of the fluid is required or where danger from fire is great.

Petroleum oils, while offering good lubricity,' are .. the least fire resistant but. are used in many applications having a marginal fire hazard due to their low cost and general availability. Previous ' attempts to render petroleum oil more fire resistant by incorporating therein known fire-resistant compounds such as phosphate esters have not produced fluids having a generally acceptable combination of lubricity, fire resistance and homogeneity. Numerous proposals have been made for correcting one or another of these properties, but correc-. tion of one property is usually effected at the expense of another property. For example, the incorporation of alkyl phosphate esters in petroleum to improve fire resistance results in fluids of marginal hydrolytic stability. The aryl phosphate esters, . while providing superior; fire resistance and h drol tic stabilit ,- can onl be added in small amounts due to the limited misclblllty of the esters in petroleum ■oils and such amounts are ineffective in producing any significant increase in fire resistance. Also, previously, aliphatic and olefinlc chlorinated hydrocarbons have been combined with mineral oil to improve fire resistance; however, they have required either the use of only minor amounts of mineral oil thus not achieving economical fire-resistant compositions or the use of significant amounts of corrosion inhibitor because the chlorinated hydrocarbons tend to be corrosive to metals.

Low-cost, fire-resistant, homogenous petroleum- containing fluids overcoming the problems of the prior art fluids have now been discovered which not only provide superior' lubricating capability but also a surprising degree of fire resistance at reasonable costs. It is, therefore, an object of this invention to provide a fire-resistant petroleum-containing fluid having a unique combination of lubricity, fire-resistance and homogeneity. Another object of this invention is to provide a reasonably low cost petroleum-containing hydraulic fluid having superior fire resistance. Still another object of this invention is to provide a fire-resistant fluid having superior lubricity. Other objects will become apparent from the following description of the invention.

According to this invention there are provided compositions useful as functional fluids which are comprised of (l) petroleum bright stock oil having a viscosity range of from about 190 to about 250 SSU at 210°F., ( 2) a phosphate ester selected from the group consisting of (i) an ester represented, by the' formula R2 where R, Ri and R2 are each selected from, the group consisting of phenyl radicals, substituted phenyl radicals and alkyl C2-18 radicals provided? that .not more than one of R, Ri .and Ra is an alkyl radical and (ii) mixtures of (i) and (3) halogenated blphenyl . .

The bright stock oil useful in compositions of this invention can be those bright stocks known to the art as conventionally refined or solvent extracted which methods can also be combined with hydrogenation. While bright stock oils can have a. viscosity in the range of from about 150 to about 300 SSU at 210°F., those which are useful in compositions of this invention have viscosities . in the range of about 190 to about 250 SSU at 210°F. Preferably the viscosity should be in the range of from about 200 to 220 SSU at 210°F.

Phosphate esters 1 useful in compositions of this inven tion can (as noted above) contain substituted and unsubstituted phenyl radicals. Such substltuents can be alkyl C1-4 radicals, chlorine, bromine or fluorine and haloalkyl C1-4 radicals. In the. case of alkyl or haloalkyl substituted phenyl radicals up . to three positions on the ring can be occupied whereas as many as four positions can be substituted by chlorine, bromine or fluorine. Typical . examples of phosphate esters useful In compo sitions of this invention are ethyl diphenyl phosphate, propyl dlphenyl phosphate, butyl, diphenyl phosphate, hexyl diphenyl phosphate, octyl- diphenyl phosphate, nonyl diphenyl phosphate, preferably Isooctyl diphenyl phosphate and 2-ethylhexyl diphenyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tri- cresyl phosphate, m-chlorophenyl dicresyl phosphate, xenyl diphenyl phosphate, . trixenyl phosphate, m-chlorophenyl diphenyl phosphate, perfluoromethylphenyl diphenyl phosphate, m-fluoro- phenyl diphenyl phosphate and bromophenyl diphenyl phosphate. The phosphate ester components of compositions of this inven- . tion can also be supplied by a mixture of esters comprising at' least one ester represented by Formula I above and at least one other phosphate ester which can be either trialkyl or dialkyl . aryl provided the resulting mixture contains an alkyl ester group to aryl ester group ratio which does not exceed 1.5 to 1 respectively. For example, a composition of this invention can be prepared wherein the phosphate ester component is a mix- ture of tris-n-butyl phosphate and isooctyl diphenyl phosphate in a weight ratio of 1 to 2 respectively. i Such a mixture of phosphate esters provides an alkyl group to aryl group ratio of slightly less than 1.5 to 1 respectively. These same exem- . plary esters, when employed in a weight ratio of 1 to 4 respec- tively, would provide an alkyl group to aryl group ratio of slightly less than 1 to 1 with the aryl groups slightly in excess.

Typical dialkyl aryl esters which can be used are • dipropyl phenyl phosphate, di-n-butyl phenyl phosphate, di- ■ tert .-butyl cresyl . phosphate, di-n-butyl chlorophenyl phosphate, di entyl phenyl phosphate, diethyl bromophenyl phos- .phate, dioctyl phenyl phosphate, dioctyl cresyl phosphate, dldecyl phenyl phosphate and dioctadecyl phenyl phosphate.

The aryl group of the dialkyl aryl phosphates may contain one or t o' substitu n rou on th ar can be used are tri-n-p.ropyl phosphate, trl-tert . -butyl phosphate tri-lsobutyl phosphate, tri-2-ethylhexyl phosphate, tri-'' capryl phosphate, trldecyl phosphate, tris-trldecyl phosphate and trioctadecyl phosphate.

The halogenated blphenyl compounds useful in compositions of this invention can contain chlorine or bromine or combinations thereof in amounts corresponding to mono-, in the case of bromine only, di-, tri-, tetra-, penta- and hexahalobiphenyl . Typical of such blphenyl compounds are the chlorinated biphenyls commercially available as products containing 32$, 42$, 48$, 54$ and 60$ by weight of combined chlorine. The expression halogenated blphenyl containing a statedpercentage of combined, halogen is used herein as including the directly halogenated products, halogenated products containing more than one specie of halogen in the same molecule and blends of one or more of such halogenated products whereby the halogen content is broadly within the range of about 30 to βθ$, preferably within the range of about 30 to 42$ b weight.' Although not preferred, minor amounts of halogenated terphenyl can be present in the halogenated blphenyl. Halogenated quaterphenyl may also be present in small amounts up to about 5$ by weight. Such minor amounts of halogenated terphenyl and quaterphenyl do not significantly alter the characteristics of the compositions of this ■ Invention. Also within the scope of this invention it is con- templated to use tri- and tetrachlorobenzene or mixtures thereof as a diluent in compositions of this invention. Such chloro-• benzenes can be employed in. amounts up to about 30 by weight of the halogenated biphenyl.

Compositions of this invention in general terms con from about 5 to about 63 phosphate ester and from about 25$ . to about 70$ halogenated biphenyl with each component present within their respective ranges so that the total of the three components is 100$. The compositions of this invention can be more readily determined by reference to Figure I which shows the weight percent of components (l), ( 2 ) and ( 3 ) required to produce the compositions of this Invention. Thus, while the components (l), ( 2 ) and ( 5 ) used to provide the compositions of this invention can be combined in a fairly wide range of proportions the unique combination of homogeneity, fire resistance and synergistic lubricity characteristic of such compositions is only obtained when such components are present in certain critical amounts which are defined by the area within the curve ABC of Figure I.

While homogeneity at a temperature of at least about 150°F. is obtained when employing any phosphate described above in any amount indicated by the area defined by the curve ABC in Figure I, functional fluids are desirably homogeneous at room temperature, i.e., about 70°F. When using phosphate esters having less than about 10 alkyl carbon atoms in the molecule, however, the amounts of such esters must be further limited within the area defined by the curve ABC of Figure I in order to provide compositions which are .. homogeneous at room temperature. More specifically, in such "'.'·■ phosphate esters the alkyl carbons can be located in a single ester group, distributed among aryl ester groups as substltu- ents on the aryl nucleus or divided between aryl substituents and an alkyl ester group. Maximum concentrations of typical phosphate esters having less than 10 alkyl carbon atoms and providing compositions homogeneous at 70°F. are illustrated by lines I, cresyl dlphenyl phosphate, II, tricresyl phosphate, and III, isooctyl diphenyl phosphate, in Figure I, which lines are 70°F. isotherms indicating maximum weight percent amounts of such esters. Thus, the compositions of this invention which are homogeneous at 70°F. and which contain isooctyl diphenyl phosphate, tricresyl phosphate and cresyl diphenyl phosphate . are defined by the area within the curves AFF'C, AEE'C and DD'C, respectively.

It has also been discovered that certain of the components (l), ( 2) and ( 3) above, when combined in certain proportions, produce functional fluids having surprisingly small rates of change of viscosity with change of temperature, which property is highly desirable in fluids employed as lubricants and as hydraulic fluids. This property is highly unexpected in view of the relatively high rates of change of viscosity with temperature found in some of the individual components..

Thus preferred compositions of this invention which have a small rate of change of viscosity with change of temperature are those containing (la) bright stock oil havin a viscosity index of at least about 90, preferably about 95 and a viscosity in the range of from about 190 to about 250 SSU at 210°F., ( 2a ) phosphate esters as described hereinabove in . Formula I with the exception that the alkyl and haloalkyl sub-stituents on the aryl radicals can contain no more than one carbon atom and ( 3a ) halogenated biphenyl containing from about 30$ to about 50 combined halogen by weight. Thus, preferred compositions of this invention contain from about 22$ to about 65$ bright stock oil, from about 5$ to about ½' $: phosphate ester and from about 2 $ to about 70$ halogen' shows the weight percent of components (la), (2a) and ( 3a ) required to produce preferred compositions of this invention ; Thus, preferred compositions of this invention having the combined properties of fire resistance, synergistic lubricity, homogeneity and good viscosity characteristics are obtained, only when such components are present in certain critical amounts- which are defined by the area within the curve AFG'G of Figure II.

Preferred compositions of this invention are those : which contain, by, weight, from about 25$ to about of a bright stock oil having a viscosity in the range of from · about 190 to 250 SSU at 210°F. and a viscosity index of at 'least about 90, from about 10$ to about 15$ of an alkyl Cz-χβ dlaryl phosphate and from about 40$ to about 60$ of a chlorinated biphenyl containing from about > to about by weight, combined chlorine.

When triaryl phosphate esters are employed, preferred compositions having weight percent proportions of (la), (2a) and (35a) within the area of the curve AFG'G of · · Figure II have a viscosity index rating of at least about +20 and when alkyl diaryl phosphate esters are employed viscosity index ratings of at least about +35 are obtained. Vlscos.lty measurements of illustrative, preferred compositions ,of this invention were made according to ASTM Method D- 445-5^ using a Cannon-Fenske modified Ostwald viscometer and are set forth in Tnble I below in centistoke units. The viscosity indices appearing in Table I were determined according to ASTM Method D 67-53 . The amounts of each component listed in Table I are in. weight percent of the final composition.

TABLE'"I As indicated' in Table I above, surprisingly high viscosity indices are obtained with the preferred compositions of this in ention Ln view of the extremely low viscosity indices of the components making up the major weight percent amounts of the compositions. Also, it is to be noted that these, relatively high readings were obtained without the. use of viscosit index Improvers. Commonly used viscosity index improvers such ..as the methacrylates and polyalkylacrylates. are ■ known to possess the preferred compositions of this invention in that good viscosity characteristics are obtained without sacrificing the . shear stability of the fluid by the use of viscosity index improvers. In some instances, however, it may be desirable to add viscosity index improvers when a higher viscosity index is more important than shear stability.

Another of the unique features of the compositions of this Invention is that while each of the components of such compositions has fairly good lubricating ability, the comp sl- tions defined by the area within the curve ABC of Figure I possess greater lubricating ability than any of such components The surprising synergistic lubricating properties found in the ■ compositions of this invention are demonstrated by the data contained in Tables II and III below. These data were obtained using a. "Timken Extreme-Pressure Lubricant Testing Machine, " which is a machine designed to determine the ability of a lubri cant to prevent a. test block from being seized or abraded by a • rotating, tapered roller bearing (test cup) under a known load. ' The test block and test cup are in lubricated contact with each other during a test period! of ten minutes during which time the bearing is rotated at 8l0 R.P.M. under a known load. After the test period the machine is stopped and the test block inspected A new test block and test cup is installed and if no evidence' of. seizure or abrasion is found on the previously used test - block, the test is repeated with a five pound increase in load. This procedure is repeated until damage to the test block is observed. If seizure or abrasion is observed on the first run, the test is repeated .with five pound incremental decreases in the. load until no damage, to the test block is observed. The highest load run without observing damage to the test block contains the data thus obtained when individual components of the compositions of this invention were employed as the lubricant. In Table III, data are presented from test runs employing typical examples of compositions of this invention-. In each instance unless otherwise stated, a Mid-Continent bright stock oil having a Viscosity of 200 SSU at 210°P. was. used.

TABLE II *Contains, by. weight, 23$ chlorinated terphenyl and 2$ chlorinated quaterphenyl .

TABLE III chlorinated terphenyl and 2$ Another property of the unique compositions of this invention is their outstanding fire resistance even though' they contain significant amounts of a bright stock. oil. To illustrate the fire resistance of the compositions of this invention their · typical properties and the properties of other commercially used fire-resistant hydraulic fluids are set forth in Table IV, below. The test procedures used to measure the various properties of the fluids of this invention and those used as comparisons are: as follows: Two tests were used for the measurement of the fire-resistance of the instant fluids since. there is no . single test that can be used to evaluate all types of fluids under all expected use conditions. The degree of. fire-resistance in any given test is influenced by the characteristics of the fluid, the type of flame or source of ignition, the total amount of energy available in rela-tion to the amount of fluid, the physical state of the fluid and many other factors. One of the tests was designed to simulate conditions resulting from a broken line spraying hydraulic fluid into various sources of ignition and is known as the "High-Pressure Spray Test." An additional test often used, which is: a smaller scale test, Is the Molten-Metal Pour Test. In this test the fluid under evaluation is dropped from a medicine dropper or poured, from a calibrated test tube onto the surface of molten aluminum alloy which has been heated to about 1250°F. If spontaneous ignition does not occur, a spark is placed in the vapors to determine if they can be ignited.

In addition to the above, the compositions of this · invention are shear stable and are not prone to foaming and any foam formed is not stable. Furthermore, the claimed com- positions have good stability, even at temperatures of 250°F. and in the presence of air, and are essentially non-corrosive to metals such as aluminum, aluminum bronze alloy, iron, silver and titanium. A further advantage of the instant compositions- is their outstanding hydrolytic stability.

As a result of the excellent physical properties' of the fluids particularly described in the preceeding examples, improved hydraulic pressure devices can be prepared, in accordance with this invention which comprise in combination a fluid chamber and an actuating fluid in said chamber, said fluid comprising one o the compositions hereinbefore described. In such a hydraulic apparatus wherein a movable member is actuated by the above-described functional fluids, performance characteristics are obtainable which are superior to those heretofore obtainable.

Because of the excellent fire-resistance of the compositions of this invention and good lubricity, they can be utilized in those hydraulic systems wherein power must be transmitted and the, frictional parts of the system lubri-. cated by the hydraulic fluid utilized. Thus, the novel •functional fluids of this invention find utility in the transmission of power in a hydraulic system having a pump therein supplying the power for the system. In such a'system, the parts which are so lubricated include the frictional surfaces of the source of power, namely the pump, valves, operating pistons and cylinders, fluid motors, and in some cases, for The pumps may be of various types, Including the piston-type pump, more particularly the variable-stroke piston pump, the variable-discharge or variable displacement piston pump, radial-piston pump, axial-piston pump, in which a pivoted cylinder block is adjusted at various angles with the piston assembly, for example, the Vickers Axial-Piston Pump, or in which the mechanism which drives the pistons is set at an angle adjustable with the cylinder block; gear-type pump, which may be spur, helical or herringbone gears, variations of inter-nal gears, or a screw pump; or vane pumps. The valves may be stop valves, reversing valves, pilot valves, throttling valves, sequence valves or relief valves. Fluid motors are usually constant or variable-discharge piston pumps caused to rotate by the pressure of the hydraulic fluid, of the system with the . power supplied by the pump power source. Such a hydraulic motor may be used in connection with a variable-discharge pump to form a variable-speed transmission.

In addition to the above, compositions of this invention can be utilized as gear lubricants in mechanical power trains. Mild mineral oil E.P. gear lubricants currently employed commercially provide ratings within' the ranges of 45 to 65 pounds when tested by the Timken Extreme Pressure Lubricant Testing Machine described above and typical paraffinic ' petroleum oil employed as a gear lubricant (having a viscosity of about 500 SSU at 100°F. provide ratings in the range of only 10 to 20 pounds. Accordingly, in view of the high ratings reported in Table III above (50 to 65 pounds), compositions this- invention can be used alone or in combination with lubricant adjuvants as lubricants in automotive and other .mobile e ui ment ower' trains . Also, com ositions of this invention are heavier than water thus making their use as gear lubricants even more desirable in applications such as in sheet metal rolling mill power trains where water contamination is likely. This property allows water contamination to be more easily removed by floatation of the water and renders such water contamination less harmful than in prior lubricants containing mineral oil.

The compositions of this invention can also contain dyes, pour point depressants, antioxidants, viscosity index improvers, such as polyalkylacrylates and polyalkyl-methacrylates, anti-rust agents, hydrolytic stabilizers and the like.

While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the inventίion is not limited thereto and that it can be variously practiced within the scope of' the following claims ·

Claims (1)

1. HAVING NOW particularly described and ascertained the nature of ou said invention and in what manner the same is to be performed , we declare that WHAT IS CLAIMED IS: ' ■ functional fluid 1 1. A /composition comprising a mixture of (1) bright stock oil haying a^ viscosity in the range of from about 190 to about 250 SSU at 210eF., (2) phosphate . ester selected from the group consisting of (i) an ester represented by the formula 0 R -.0 - P - 0 - R-i Ra ■ · '. where R, Ri and R2 are each selected from the group consisting of phenyl, alkyl C2-18 radicals, and substituted phenyl radicals .provided hot more than one of R, Ri and R2-are alkyl and (ii) mixtures of (i) . ; and (3) halogenated blphenyl wherein the amounts of (l), (2) and (3) are within the area defined by the curve ABC of Figure I. · 2. A composition of Claim 1 where the halogenated biphenyl is chlorinated blphenyl containing from about 50 to about 6oo by weight combined chlorine. 3· A composition of Claim 1 where the phosphate ester is an alkyl diaryl phosphate. 4.. A composition of Claim 3 ^where the phosphate ester is 2-ethylhexyl diphenyl phosphate. 5« A composition of Claim 1 where the phosphate ester is cresyl diphenyl phosphate. 6. A composition of Claim 3 where the phosphate 7. A composition of Claim 1 where the bright stock oil has a viscosity in the range of about 200 to about 220 SSU at 210°F.. functional fluid 8. A/composition comprising a mixture of (1) "bright stock oil having a viscosity in the range of from about 190 to about 250 SSU at 210°P. and a viscosity index of at least about 90, (2) a phosphate ester selected from the group consisting of (i) esters represented by the formula 0 R - O - P - O -'R ' 0 t E2 where R, and Rg are each selected from the group consisting of alkyl 3 » phenyl, substituted phenyl radicals wherein the substituents are selected from the group... consisting of hydroxyl, methyl and halpmethyl radicals and (ii) mixtures of (i) and t (3) halogenated biphenyl containing from about 30 to about 50 by weight combined halogen wherein the amounts of ( 1 )', (2) and (3) are within the /area defined by. the curve AFG'G- of Figure II. 9. A composition of claim 8 where the phosphate ester is tricresyl' phosphate . 10. A composition of Claim 8 where the . phosphate ester is isooctyl diphenyl phosphate.. 12. A composition of Claim 8 where the bright stock · oil has a viscosity in the range of from about 200 to 220 SSU at 210°F. , „ functional, fluid . ·. ' . ^ . , ^ 13. A /composition comprising a mixture by weight of from about 25$ to about $ of a bright stock oil having a viscosity in the range of from about 190 to 250 SSU at 210°P.-and a viscosity index of at least about 90, from about 10$ to about 15$ of .an alkyl 02_18 diaryl phosphate and from about 40$ to about 60$ of a chlorinated biphenyl containing from about 30$ to about 54$, by weight, combined chlorine. 14. A composition of Claim 13 where the bright stock oil has a viscosity in the range of from about 200 to 220 SSU at 210°I1. and the viscosity index is at least about 95. 15. A composition of Claim 13 where the phosphate ester is an alkyl diphenyl phosphate. 16. A composition of Claim 13 where the phosphate ester is isooctyl diphenyl phosphate. 17. A composition of Claim 13 where the phosphate ester is tricresyl phosphate. 18. A composition of Claim 13. where the chlorinated biphenyl contains about 42$ by weight combined chlorine. functional fluid .19· A/composition comprising a mixture of (1) bright stock oil having a viscosity in the range of from about 190 to 250 SSU at 210°P. , (2) a mixture of phosphate esters comprising (i) at least one ester represented by the formula • 0 II R - .0 - P - 0 - .R1 I ' ' 0 where ,R1 and 2 are each selected from the group consisting of phenyl, alkyl C2-18 radica:i-s» an(i sub- . · stituted phenyl radicals provided not more than one of R, .J. and R2 are alkyl and (ii) at least one ester selected from the group consisting of trialkyl phosphates and dialkylaryl phosphates, the maximum ratio of alkyl ester groups to' aryl ester groups being about 1.5 to 1 respectively; and (3.) halogenated biphenyl wherein the amounts of (1), (2). and (3) are within the area defined by the curve ABC. of Figure I. 20. A composition of Claim 19 where the bright stock oil has a viscosity in the range of from about 200 to 220 SSU . at 210°P. 21. A composition of Claim 19 where the mixture of phosphate' esters comprises at least one ■ alkyl diaryl phosphate and. at least one trialkyl phosphate. 22. A composition of Claim 19 where .. the mixture of phosphate .esters comprises at least one triaryl phosphate and at least one tria-lkyl phosphate. 23. A composition of Claim 21 where the mixture of 24. A composition of Claim 19 where the halogenated biphenyl is chlorinated biphenyl containing from about 30$ to about 60$, by weight, combined chlorine. . 25. A composition .comprising, by weight, about 25$ bright stock oil having a viscosity of about 200 SSU at 210°F., about 14$ isooctyl diphenyl phosphate and about 61$ chlorinated biphenyl containing about 42$ chlorine. 26. A hydraulic system containing as the operative fluid a composition of Claim 1. 27. A hydraulic system containing as the operative fluid a composition of Claim 13. 28. In the method .of operating a hydraulic pressure .device wherein a displacing force is transmitted to a displace-able member by means of a hydraulic fluid--, the improvement . which comprises employing as said hydraulic fluid a composition of Claim 1. v' . Functional fluid compositions and hydraulic systems, 29. An invejti-Qja./substantially as described and disclosed herein. DATED THIS 13th day Attorneys for App icants