# US 11,299,688 B2 · Polysiloxane hydraulic fluids

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- Number: US 11,299,688 B2
- Document ID: US11299688B2
- Status: Granted
- Kind: B2
- Application number: 16/300,579
- Filed: 2017-05-11
- Published: 2019-09-19
- Granted: 2022-04-12
- Earliest claimed: 2016-05-11
- Assignees: The Boeing Company
- Applicants: The Boeing Company; Commonwealth Scientific and Industrial Research Organisation
- Inventors: Mathew John Ballard; Philip Stephen Casey; Susan Wan-Yi Holmes; Cameron David Way; Kevin Norman Winzenberg; James Hull
- Web page: https://patentgrep.com/patent/US11299688B2

## CPC

- C10M 107/50: containing silicon
- C08G 77/04: Polysiloxanes
- C08G 77/045: {containing less than 25 silicon atoms}
- C08K 5/5333: Esters of phosphonic acids
- C08K 5/5357: cyclic
- C08L 83/04: Polysiloxanes
- C10M 111/04: at least one of them being a macromolecular organic compound
- C10M 137/12: having a phosphorus-to-carbon bond
- C10M 141/12: at least one of them being an organic compound containing atoms of elements not provided for in groups C10M141/02 - C10M141/10
- C08G 77/70: {Siloxanes defined by use of the MDTQ nomenclature}
- C08G 77/80: {Siloxanes having aromatic substituents, e.g. phenyl side groups}
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- C10M 2223/06: having phosphorus-to-carbon bonds
- C10M 2223/065: containing sulfur
- C10M 2229/042: containing aromatic substituents
- C10M 2229/0425: used as base material
- C10N 2030/02: Pour-point; Viscosity index
- C10N 2030/36: {Seal compatibility, e.g. with rubber}
- C10N 2040/08: Hydraulic fluids, e.g. brake-fluids
- C10M: LUBRICATING COMPOSITIONS (well drilling compositions C09K8/02); USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION (mould release, i.e. separating, agents for metals B22C3/00, for plastics or substances in a plastic state, in general B29C33/56, for glass C03B40/02; textile lubricating compositions D06M11/00, D06M13/00, D06M15/00; immersion oils for microscopy G02B21/33)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C10N: INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS

## Abstract

The present disclosure relates to polysiloxanes, processes for preparing polysiloxanes, and hydraulic fluids comprising polysiloxanes. This disclosure also relates to hydraulic fluids comprising one or more polysiloxane compounds and diphosphonate compounds, and to the use of diphosphonate compounds in hydraulic fluids or as additives or components in various compositions, for example to provide fire retardant properties to a fluid or composition. This disclosure also relates to use of the compositions as hydraulic fluids, which may be used in various machines, vehicles and craft, including aircraft.

## Claims

### Claim 1

A hydraulic fluid composition comprising a polysiloxane compound and a non-halogenated diphosphonate compound, wherein the polysiloxane compound is represented by a compound Formula 1
wherein
y is an integer selected from 1 to 40;
R1, R2, R3, and R4, are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl;
each R5 and each R6 are independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
at least one of R1 to R4, or at least one of R5 and R6 from at least one of the y units, is C1-10alkylaryl,
wherein the polysiloxane compound has a mol % of aryl moieties of about 15 mol % to about 35 mol %, relative to silicon,
wherein the polysiloxane compound is present in the composition at a polydispersity of about 1 to about 5, and
wherein the non-halogenated diphosphonate compound is represented by a compound of Formula 2:
wherein:
X is selected from a group consisting of an aryl, C1-20alkylaryl, and C1-20dialkylaryl; and
R11, R12, R13, and R14 are each independently selected from a group consisting of C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 2 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the polysiloxane compound of Formula 1 is represented by a compound of Formula 1a:
wherein
x is an integer selected from 0 to 10;
y is an integer selected from 1 to 20;
z is an integer selected from 0 to 10;
R1, R2, R3, and R4, are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl;
each R5 and each R6 are independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
each R7, R8, R9, and R10, is independently selected from C1-10alkyl.

### Claim 3 (depends on 2)

The hydraulic fluid composition of claim 2, wherein each R7, R8, R9, and R10, is methyl and x and z are integers each independently selected from 1 to 3.

### Claim 4 (depends on 2)

The hydraulic fluid composition of claim 2, wherein y is an integer selected from 2 to 16 or the sum of x, y and z, is an integer selected from 2 to 16.

### Claim 5 (depends on 2)

The hydraulic fluid composition of claim 2, wherein R1 and R2 are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; each R3, R4, R5, R7, R8, R9, and R10, is C1-4alkyl; and wherein each R6 and y is selected to provide the polysiloxane compound of Formula 1a with between 1 to 6 optional substituents independently selected from the group consisting of aryl and C1-10alkylaryl and any other substituents for each R6 is independently selected from C1-4alkyl.

### Claim 6 (depends on 5)

The hydraulic fluid composition of claim 5, wherein each R3, R4, R5, R7, R8, R9, and R10, is methyl, and each R6 is independently selected from the group consisting of methyl, aryl, and C1-10alkylaryl.

### Claim 7 (depends on 1)

The hydraulic fluid composition of claim 1, wherein at least one or both of R1 and R2 are selected from the group consisting of aryl and C1-10alkylaryl.

### Claim 8 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the C1-10alkylaryl is a C1-6alkylphenyl.

### Claim 9 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition comprises a mixture of at least two polysiloxane compounds of Formula 1.

### Claim 10 (depends on 9)

The hydraulic fluid composition of claim 9, wherein the polysiloxane mixture comprises a series of different polysiloxane compounds of Formula 1 each having a different y value or a number of siloxane repeat units (Si—O) selected from and including each integer from 6 to 17.

### Claim 11 (depends on 9)

The hydraulic fluid composition of claim 9, wherein the polysiloxane mixture comprises at least four polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 9 to 12 repeat units.

### Claim 12 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the diphosphonate compound is represented by a compound of Formula 2(a)(i):
wherein
m is an integer selected from 1 to 10;
R11, R12, R13, and R14, are each independently selected from the group consisting of C1-20alkyl, aryl, and C1-20alkylaryl; and
each R15 and R16 is independently selected from the group consisting of hydrogen, C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 13 (depends on 12)

The hydraulic fluid composition of claim 12, wherein
m of Formula 2(a)(i) is an integer selected from 1 to 6;
R11, R12, R13, and R14, are each independently selected from the group consisting of C1-10alkyl and C1-10alkylaryl; and
each R15 and R16 of Forumla 2(a)(i) is independently selected from the group consisting of hydrogen and methyl.

### Claim 14 (depends on 12)

The hydraulic fluid composition of claim 12, wherein
m of Formula 2(a)(i) is an integer selected from 1 to 6;
R11, R12, R13, and R14 of Formula 2(a)(i) are each independently selected from C2-10alkyl; and
each R15 and R16 of Formula 2(a)(i) is hydrogen.

### Claim 15 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition further comprises a phosphonate compound represented by a compound of Formula 3:
wherein
R17, R18, and R19, are each independently selected from the group consisting of C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 16 (depends on 15)

The hydraulic fluid composition of claim 15, wherein R17, R18, and R19, are each independently selected from the group consisting of C1-10alkyl and C1-10alkylaryl.

### Claim 17 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the amount of polysiloxane compound, based on weight % of the composition, is provided at between about 10 and 90%.

### Claim 18 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the volume ratio of the polysiloxane compound to the diphosphonate compound in the composition is provided at a volume ratio between about 4:1 and 1:4.

### Claim 19 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition further comprises or consists of an additive selected from the group consisting of an acid scavenger, an anti-erosion additive, a viscosity index improver, an antifoaming agent, an antioxidant, an anti-corrosion additive, and any combinations thereof.

### Claim 20 (depends on 19)

The hydraulic fluid composition of claim 19, wherein the composition further comprises or consists of an additive selected from the group consisting of an acid scavenger, an antifoaming agent, an antioxidant, and any combinations thereof.

### Claim 21 (depends on 19)

The hydraulic fluid composition of claim 19, wherein the acid scavenger is selected from the group consisting of a phenylglycidyl ether, pinene oxide, styrene oxide, glycidyl cyclohexyl ether, glycidyl epoxycyclohexyl ether, diglycidyl ether, glycidyl isopropyl ether, butadiene dioxide cyclohexylene oxide, bis-epoxycyclohexyl adipate, 3,4-epoxycyclohexylcarboylate and 3,4-epoxycyclohexane, and any combinations thereof.

### Claim 22 (depends on 19)

The hydraulic fluid composition of claim 19, wherein the antifoaming agent is selected from the group consisting of a silicone oil, polyvinyl alcohol, polyether, and any combinations thereof.

### Claim 23 (depends on 19)

The hydraulic fluid composition of claim 19, wherein the antioxidant is selected from the group consisting of a 2,6-di-tert-butyl-p-cresol, phenyl-α-napthylamine, di(octylphenyl)amine, 6-methyl-2,4-bis(octylthio)-methyl-phenol, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)], and any combinations thereof.

### Claim 24 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition is substantially free of fluorinated anti-erosion additives.

### Claim 25 (depends on 24)

The hydraulic fluid composition of claim 24, wherein the composition is substantially free of any perfluorinated anionic surfactant.

### Claim 26 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition is substantially free of any one or more additional viscosity index improver selected from the group consisting of poly(alkyl acrylate), poly(alkyl methacrylate), poly(alkyl methacrylate) esters, polycyclic polymers, polyurethanes, polyalkylene oxides, and polyesters.

### Claim 27 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the flash point of the composition is between 160 and 300° C. when measured using flash point testing method of ASTM D4206 of 2-4 ml volumes with a Stanhope Seta Open Cup Apparatus.

### Claim 28 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the density (gcm−3 at 298K) of the composition is less than 1.5.

### Claim 29 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the composition exhibits a viscosity between about 5 and about 25 centipoises at about 100° F. and between about 500 and about 3500 centipoises at −65° F.

### Claim 30 (depends on 1)

The hydraulic fluid composition claim 1, wherein the composition is effective for use as a fire resistant hydraulic fluid.

### Claim 31 (depends on 30)

The hydraulic fluid composition of claim 30, wherein the composition is effective for use as a hydraulic fluid in aircraft.

### Claim 32 (depends on 1)

A process for preparing a hydraulic fluid composition comprising adding together in a composition, in any order, the polysiloxane compound of Formula 1 and diphosphonate compound as defined in claim 1.

### Claim 33 (depends on 32)

The process of claim 32, whereby the hydraulic fluid composition is prepared by adding into the composition, in any order, at least one of a phosphonate compound or additive.

### Claim 34

A hydraulic fluid composition comprising:
a polysiloxane compound of Formula 1:
wherein
y is an integer selected from 4 to 40;
R1, R2, R3, and R4, are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl;
each R5 and each R6 is independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
wherein at least one of R1 to R4, or at least one R5 and R6 from at least one of the y units, is C1-10alkylaryl,
wherein the polysiloxane compound has a mol % of aryl moieties of about 20 mol % to about 30 mol %, relative to silicon,
wherein the polysiloxane compound is present in the composition at a polydispersity of about 1 to about 5; and
a non-halogenated diphosphonate compound represented by a compound of Formula 2:
wherein:
X is selected from a group consisting of an aryl, C1-20alkylaryl, and C1-20dialkylaryl; and
R11, R12, R13, and R14 are each independently selected from a group consisting of C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 35 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the polysiloxane compound of Formula 1 is represented by a compound of Formula 1a:
wherein
x is an integer selected from 0 to 10;
y is an integer selected from 4 to 20;
z is an integer selected from 0 to 10;
R1, R2, R3, and R4, are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl;
each R5 and each R6 are independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
each R7, R8, R9, and R10, is independently selected from C1-10alkyl; and
wherein at least one of R1 to R4, or at least one of R5 to R10 from at least one of the x, y or z units, is C1-10alkylaryl.

### Claim 36 (depends on 35)

The hydraulic fluid composition of claim 35, wherein each R7, R8, R9, and R10, is methyl and x and z are integers each independently selected from 1 to 3.

### Claim 37 (depends on 34)

The hydraulic fluid composition of claim 34, wherein y is an integer selected from 4 to 16 or the sum of x, y and z, is an integer selected from 4 to 16.

### Claim 38 (depends on 34)

The hydraulic fluid composition of claim 34, wherein R1 and R2 are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; each R3, R4, R5, R7, R8, R9, and R10, is C1-4alkyl; and wherein each R6 and y is selected to provide the polysiloxane compound of Formula 1a with between 1 to 6 optional substituents independently selected from the group consisting of aryl and C1-10alkylaryl and any other substituents for each R8 is independently selected from C1-4alkyl.

### Claim 39 (depends on 38)

The hydraulic fluid composition of claim 38, wherein each R3, R4, R5, R7, R8, R9, and R10, is methyl, and each R6 is independently selected from the group consisting of methyl, aryl, and C1-10alkylaryl.

### Claim 40 (depends on 34)

The hydraulic fluid composition of claim 34, wherein at least one of R1 and R2 is C1-10alkylaryl.

### Claim 41 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the C1-10alkylaryl is a C1-6alkylphenyl.

### Claim 42 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition comprises a mixture of at least two polysiloxane compounds of the Formula 1.

### Claim 43 (depends on 42)

The hydraulic fluid composition of claim 42, wherein the polysiloxane mixture comprises a series of different polysiloxane compounds of Formula 1 each having a different y value or a number of siloxane repeat units (Si—O) selected from and including each integer from 6 to 17.

### Claim 44 (depends on 43)

The hydraulic fluid composition of claim 43, wherein the polysiloxane mixture comprises at least four polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 8 to 13 repeat units.

### Claim 45 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition further comprises a phosphonate compound of Formula 3:
wherein
R17, R18, and R19, are each independently selected from the group consisting of C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 46 (depends on 45)

The hydraulic fluid composition of claim 45, wherein R17, R18, and R19, are each independently selected from the group consisting of C1-10alkyl and C1-10alkylaryl.

### Claim 47 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the amount of polysiloxane compound, based on weight % of the composition, is provided at between about 10 and 90%.

### Claim 48 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition further comprises or consists of an additive selected from the group consisting of an acid scavenger, an anti-erosion additive, a viscosity index improver, an antifoaming agent, an antioxidant, anti-corrosion additive, and any combinations thereof.

### Claim 49 (depends on 48)

The hydraulic fluid composition of claim 48, wherein the composition further comprises or consists of an additive selected from the group consisting of an acid scavenger, an antifoaming agent, an antioxidant, and any combinations thereof.

### Claim 50 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition is substantially free of fluorinated anti-erosion additives.

### Claim 51 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition is substantially free of any one or more additional viscosity index improver selected from the group consisting of poly(alkyl acrylate), poly(alkyl methacrylate), poly(alkyl methacrylate) esters, polycyclic polymers, polyurethanes, polyalkylene oxides, and polyesters.

### Claim 52 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the flash point of the composition is between 160 and 300° C. when measured using flash point testing method of ASTM D4206 of 2-4 ml volumes with a Stanhope Seta Open Cup Apparatus.

### Claim 53 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the density (gcm3 at 298K) of the composition is less than 1.5.

### Claim 54 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition exhibits a viscosity between about 5 and about 25 centipoises at about 100° F. and between about 500 and about 3500 centipoises at −65° F.

### Claim 55 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the composition is effective for use as a fire resistant hydraulic fluid or a hydraulic fluid in aircraft.

### Claim 56 (depends on 34)

A process for preparing a hydraulic fluid composition comprising combining together in a composition, in any order, the polysiloxane compound of Formula 1 and one or more additional compounds and additives, wherein each of the one or more polysiloxane compounds of Formula 1, one or more additional compounds including phosphonate compounds of Formula 3, and one or more additional additives, are as defined according to claim 34.

### Claim 57

A hydraulic fluid composition comprising:
a polysiloxane compound of Formula 1:
wherein
y is an integer selected from 4 to 25;
each R3 and R4 are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
each R5 and each R6 is independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
each R1 and R2 is independently C1-10alkylaryl,
wherein the polysiloxane compound has a mol % of aryl moieties of about 15 mol % to about 35 mol %, relative to silicon, and
a non-halogenated diphosphonate compound represented by a compound of Formula 2:
wherein:
X is selected from a group consisting of an aryl, C1-20alkylaryl, and C1-20dialkylaryl; and
R11, R12, R13, and R14 are each independently selected from a group consisting of C1-20alkyl, aryl, and C1-20alkylaryl.

### Claim 58 (depends on 57)

The hydraulic fluid composition of claim 57, wherein the polysiloxane compound of Formula 1 is represented by a compound of Formula 1a:
wherein
x is an integer selected from 0 to 10;
y is an integer selected from 4 to 20;
z is an integer selected from 0 to 10;
each R1 and R2 is independently C1-10alkylaryl;
each R3 and R4 are each independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl;
each R5 and each R6 are independently selected from the group consisting of C1-10alkyl, aryl, and C1-10alkylaryl; and
each R7, R8, R9, and R10 is independently selected from C1-10alkyl.

### Claim 59 (depends on 58)

The hydraulic fluid composition of claim 58, wherein each R7, R8, R9, and R1 is methyl and x and z are integers each independently selected from 1 to 3.

### Claim 60 (depends on 57)

The hydraulic fluid composition of claim 57, wherein y is an integer selected from 4 to 16 or the sum of x, y and z is an integer selected from 4 to 16.

### Claim 61 (depends on 57)

The hydraulic fluid composition of claim 57, wherein each R3, R4, R5, R7, R8, R9, and R1 is C1-4alkyl; and wherein each R6 and y is selected to provide the polysiloxane compound with between 1 to 6 additional substituents independently selected from the group consisting of aryl and C1-10alkylaryl and any other substituents for each R6 is independently selected from C1-4alkyl.

### Claim 62 (depends on 61)

The hydraulic fluid composition of claim 61, wherein each R3, R4, R5, R7, R8, R9, and R10 is methyl, and each R6 is independently selected from the group consisting of methyl, aryl, and C1-10alkylaryl.

### Claim 63 (depends on 57)

The hydraulic fluid composition of claim 57, wherein each R1 and R2 is independently C1-6alkylphenyl.

### Claim 64 (depends on 57)

The hydraulic fluid composition of claim 57, wherein the composition comprises a mixture of at least two polysiloxane compounds of Formula 1.

### Claim 65 (depends on 64)

The hydraulic fluid composition of claim 64, wherein the polysiloxane mixture comprises a series of different polysiloxane compounds of Formula 1 each having a different y value or a number of siloxane repeat units (Si—O) selected from and including each integer from 6 to 17.

### Claim 66 (depends on 64)

The hydraulic fluid composition of claim 64, wherein the polysiloxane mixture comprises at least four polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 9 to 12 repeat units.

### Claim 67 (depends on 57)

The hydraulic fluid composition of claim 57, wherein the composition is effective for use as a fire resistant hydraulic fluid or a hydraulic fluid in aircraft.

### Claim 68 (depends on 57)

A process for preparing a hydraulic fluid composition comprising combining together in a composition, in any order, the polysiloxane compound of Formula 1 according to claim 57 with one or more additional compounds and/or additives.

### Claim 69 (depends on 10)

The hydraulic fluid composition of claim 10, wherein the polysiloxane mixture comprises at least six polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 8 to 13 repeat units.

### Claim 70 (depends on 43)

The hydraulic fluid composition of claim 43, wherein the polysiloxane mixture comprises at least four polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 9 to 12 repeat units.

### Claim 71 (depends on 64)

The hydraulic fluid composition of claim 64, wherein the polysiloxane mixture comprises at least six polysiloxane compounds each having a different number of siloxane repeat units (Si—O) selected from 8 to 13 repeat units.

### Claim 72 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the polysiloxane compound is present in the composition at a polydispersity of about 1 to about 3.

### Claim 73 (depends on 34)

The hydraulic fluid composition of claim 34, wherein the polysiloxane compound is present in the composition at a polydispersity of about 1 to about 3.

### Claim 74 (depends on 1)

The hydraulic fluid composition of claim 1, wherein the polysiloxane compound has a mol % of aryl moieties of about 20 mol % to about 30 mol %, relative to silicon.

### Claim 75 (depends on 57)

The hydraulic fluid composition of claim 57, wherein the polysiloxane compound has a mol % of aryl moieties of about 20 mol % to about 30 mol %, relative to silicon.

### Claim 76 (depends on 1)

The hydraulic fluid composition of claim 1, wherein each R1 and R2 is independently C1-10alkylaryl.

### Claim 77 (depends on 76)

The hydraulic fluid composition of claim 76, wherein the polysiloxane compound comprises a compound selected from the group consisting of:

### Claim 78 (depends on 34)

The hydraulic fluid composition of claim 34, wherein each R1 and R2 is independently C1-10alkylaryl.

### Claim 79 (depends on 78)

The hydraulic fluid composition of claim 78, wherein the polysiloxane compound comprises a compound selected from the group consisting of:

### Claim 80 (depends on 57)

The polysiloxane compound of claim 57, wherein the polysiloxane compound is selected from the group consisting of:

### Claim 81 (depends on 1)

The hydraulic fluid composition of claim 1, wherein X is C1-20dialkylaryl.

### Claim 82 (depends on 1)

The hydraulic fluid composition of claim 1, wherein X is aryl.