CA1100930A

CA1100930A - Oil compositions containing poly(dimethylsiloxane)

Info

Publication number: CA1100930A
Application number: CA314,316A
Authority: CA
Inventors: Jean-Claude Courtes; William C. Morro
Original assignee: Union Carbide Canada Ltd
Current assignee: Union Carbide Canada Ltd
Priority date: 1978-10-26
Filing date: 1978-10-26
Publication date: 1981-05-12

Abstract

I.D.-196 Y-942-I.D.5 OIL COMPOSITIONS CONTAINING
POLY(DIMETHYLSILOXANE) A B S T R A C T

Compositions useful as lubricating or hydraulic oil are described which consist of poly-(dimenthylsiloxane) and a solvent oil of the group consisting of certain branched chain alcohols, their monocarboxylic acid esters, and their homologous ethers.
The composition can also include a diluent oil selected from hydrocarbon oils, polyol esters, phosphate esters and polyalkylene glycol ethers.

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

Description

01~ CO~IPOSITIONS CONTAINING POLY(DIMETH~LSILOXANE) This invention relates to compositions of matter useful as lubricants and hydraulic fluids and more particularly to silicone-ester compositions which may be used as lubricants and in various hydraulic systems where extremes of temperatures are encauntered.

Lubricating oil compositions are often employed as functional fluids, transmission fluids or heat transfer fluids, such as in automatlc transmissions, pump9 and hydraulic aquipment. Hydraulic fluids having good viscosity-temperature, ~iscosity-volatillty, 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 elements of the hydraulic loop ~-at the upper temperature extreme experienced and yet be low enough to flow freely at the lowest temperature expected.

It is well known that certain liquid poly--`~ (organosiloxanes) exhibit a very high viscosity index ~` which enables them to be used as functional fluids over a broad temperature range. Poly(dimethylsiloxane) in particular, shows a performance in this area which is superior to virtually all known materials. Un~ortunately, these so-called silicone oils, especially poly(dimethylsiloxane), are incompatible with most otner materials and are econ-omically unattractive; moreover, they have poor lubricating properties when used as lubricants for metal on metal, particularly steel on s~eel applications. Their incom-patibility makes it difficult to improve their performance with additives.

~4~

~L~Uo~o In order to take advanta~e of the good vis-cosity-temperature properties of silicone oils, iC is desirable to dissolve them in lubricating oil carriers.
This has been carried out with various poly(organo-siloxanes) as described in German Patent, 1,806,44;.
However, the solubility characteristics of poly-(dimethylsiloxane) generally prevent its dispersion in liquid media, except with the aid of dispersing agents or emulsifiers such as described in U.S. 3,445,385 and U.S. 2,466,642. In those few cases where poly-(dimethylsiloxane) oil has been successfully incorporated into a ~omogeneous composition, the molecular weight of the silicone has been such that its viscosity has been limited to around 1,000 cs or less as shown in U.S. 2,652,364, British 811,813, and U.S. 2,618,601; or the lubricating oil carriers have been limited to a select group of diesters or hydro&arbons.

Numerous diester-carriers are disclosed in U.S. 2,528,535, "Effective Lubrication Range for Steel Surfaces Boundary Lubricatsd at High Sliding Velocities - by Various Classes of Synthetic Fluids."
- R. L. Johnson, et al; Natl. Advisory Comm.
Aeronaut Tech, Note No. 2846, 1952, and "Effects of Solvents in Improving Boundary Lubrication of Steel by Silicones."
S. F. Murray and R. L. Johnson, Natl.
Advisory Comm. Aeronaut Tech. Note No 2788, 1952.

, More recently, mixtures of high molecular weight (high viscosity) dimethylsiloxane polymers and selected iso-paraffinic, naphthenic, and unsaturated aliphatic hydrocarbon oil solvents, as disclosed in U.S. Patent 4,0~9,534 issued November 22, 1977 have been proposed for use as multi-purpose lubricants and functional fluids. In addition, hydraulic fluid com-positions comprising a low viscosity dimethylsiloxane ~l~00~30 oil and a hydrocarbon oil component selected from the group of napthenic oils, branched chain aliphatic hydro-carbon oils and alkylated aromatic oils for use as lubricants and hydraulic fluids are disclosed in Canadian Application Serial No. 270,641 filed January 28, 1977, while compositions comprising poly(dimethylsiloxane) of either low or high molecular weight, and a hydrocarbon oil selected from a group of olefin oligomers are disclosed as lubricants and hydraulic fluids. Canadian ~pplication Serial No. 273,020 filed ~arch 2, 1977.

Because of the restrictions on the silicone oil viscosity and the carrier, it i9 difficult to achleve the desired properties in the final formulation. Such properties would include low temperat~re compatibility, oxidation and thermal stability, good low temperature flow characteristics, limited compatibility with water, and rubber swell.

It has now been discovered that silicone-. . .
solvent oil compositions of matter can be prepared, wherein the solvent oil may be one of an alcohol, ester,or ether, which are useful as lubricants and hydraulic fluids, and which, because of their compatibility with other materials, can be used to formulate functional fluids with excellent properties.

There~ore, it is an object of this invention to provide novel silicone-hydrocarbon compositions of matter which are useful as lubricants and hydraulic fluids. More particularly, this invention may be des-cribed as a composition of matter consisting of, (A) dimethylsiloxane polymers having a viscosity of from about 5 to about l,000,000 centistokes at about 25 C, .. . . . ~

sele~ted ~rom the group consisting of linear polymers consisting essentially of siloxy units of the formula R2SiO and end-blocking silo~y units of the formula R3SiOo 5 wherein R represents a methyl radical, and cyclic polymers consisting essentially of siloxy units of the formula R2Si wherein R represents a methyl radical, and (B) solvent oils selected from the group consisting of branched chain alcohols having from 8 to 18 carbon atoms, monocarboxylic acid esters of said~ 8 to 18 carbon branched chain alcohols, and homologous ethers, all characterized by the general formula:
l3 :
Rl -C -R2 O
R

: 1 CkH2k+l, and R2 = H, or CiH2i~1' and R3 = ~ or C H2 +1' and wherein 8~(K+l~m) ~18, and the ;
I longest chain formed by Rl, R2, R3 contains~2 substituent alkyl branches, and wherein R5 = ~ or C-R5, or CH2-~

wherein R4 - H or C H2 +1 and lcncl2; and (C) a diluent oil selected from the class consisting of hydrocarbon oils, polyol esters, phosphate esters and polyalkylene glycol ethers; wherein the proportions of (A), (B) and (C) range from 1-99 per cent by weight of (A), and 1-99 per cent by weight of (B), and from 0-98 per cent by weight of (C~; and wherein the proportions and composition of (C) are selectedsuch that (B) and (C) would be miscible at 0C if mixed in the same ratio as that found in the final composition; and wherein the ternary compositions of (A), (B) and (C) of the invention are miscible at temperatures below those at which binary compositions of (C) the diluent oil, and an equal proportion by weight as in the ternary composition of (A) the silicone oil are miscible.

~as3~
It is another ob~act of the invention to provide a process for effecting movement of a movable member within an enclosing member which comprises transmitting pressure to said movable member through a liquid medium consisting essentially of a lubricating oil composi~ion as defined above.

It is still another object of the invention to provide a process for transmitting force through an bydraulic system having hydraulic activating means, an hydraulic line means connec~ing said hydraulic activating means to an hydraulic activated means, which process comprises substantially filling said hydraulic activating means, said hydraulic line means and said hydraulic acti : vated means with a lubricating oil composition as defined .~
~: above. Other objects and advantages of the invention will `
become readily apparent from the following description and appended claims.

The dimethylsiloxane oils employed in this ` invention as well as methods for their preparation are :
well known. They are selected from the class consisting of linear polymers consisting essentially of siloxy units of the formula R2SiO and end-~locking siloxy units of the R3SiOo 5 wherein R represents a methyl radical, arld cyclic polymers consisting essentially of siloxy units of the formula R2SiO, wherein R represents a me~hyl radical. These siloxane polymers are also conventionally represented by the average formulae R3SiO(R2SiO)xSiR3, and l-O-(R2SiO)x-R2Sil respectively, ` . ; ` - !

()93Q

~herein ~ is a methyl radical and x is an integer having an average value that corresponds to the viscosity of the particular siloxane. For example, a trimethyl end-blocked dimethylsiloxane oil having a viscosity of 100 centistokes at 25 C can be represented as having the average formula r Me3SiO(Me2siO)48si~e3 wherein Me is a methyl radical.

As employed herein, such siloxane oils are generally linear siloxane polymers having a viscosity in the range of about S to 1,000,000 centistokes (C9) at about 25C, and preferably 10 to 750,000 cs at about 25 C, and most preferably from 10 to 1,000 and 10,000 ~o 500,000 cs at about 25 C.

It is to be understood, of course, that while the dimethylsiloxane oils used in this invention can be ~~ discrete chemical compounds, they are usually comprised of various discrete siloxane species of similar molecular weight which produces a final mixture of relatively narrow -molecular weight distribution, due at least in part to the fact that the starting materials used to produce the siloxane oils are themselves usually mixtures. Thus, it it obvious that the dimethylsiloxane oils employed herein need not be fractionated as by distillation but may be sparged (i.e. stripped of lights) or unsparged. It is to be further understood that mixtures of 2 or more of the silicones specified herein may be used, and that they may in some cases improve the properties in a manner con-sistent with the trends identified in the following examples:

The solvent oils of the invention are generally known in the art, and include branched chain alcohols of from 8 to 18 carbon atoms inclusive, where the longest chain contains 2 or more substituent alkyl branches.

These correspond to the general formula:
l3 OH
1 Ck 2k+1~ and R2 ~ H, or CiH2i+l, and R - H or C H2 ~1~ and wherein 8e~k+i~m)c~8, and the longest chain found by R1, R2, R3contains ~2 substituen~ alkyl branches.
It is preferred that R3 - H.

10Illustrative of the more preferred alcohols that can be employed herein are the so-called oxo-alcohols - produced for branched chain hydrocarbons such as olefin oligomers, and 2, 6, 8-trimethyl-4-nonanol, the latter having the for~ula:
. . , .~ CH3 ICH3 _1 3 ., _cH_c~2-cH-CH2-CH-CH2 CH CH3 -~

OH

The solvent oils also include monocarboxylic acid esters of the branched chain alcohols having the 20general formula:

l 1 2 O
C=O ~' where Rl, R2, and R3 are the same as above, and R4 = H, or CnH2n~land lend 2. Preferably ~cn-~O, and most preferably 7~n~9. The p~repàration of such esters is well known, and generally comprises reacting 30a monocarboxylic acid with an alcohol in the presence of a water scavenging means. Illustrative of the more preferred esters that can be employed herein are those prepared with the preferred alcohols of the invention, including such compounds as 2, 6, 8-trimethyl-4-non-ylocta~oate, isodecylvalerate, and tridecy-loctanoate )093~
(the latter two prepared with isodecanol and ~ridecanol, both branched chain oxo-alcohols produced by Exxon Corp.). .
These esters are distinct from the diesters employed in the prior art, both with respect to physical and chemical properties.

The solvent oils also include ethers having the general formula:

Rl -C -R2 ; R4 where Rl, R2, R3 and R4 are the same as above. Such ethers can be prepared by numerous methods known in the art. Illustrative of the more preferred ethers that can be employed herein are 2, 6~8-trimethyl-4-nonyl -~
octyl ether, and isodecyl pentyl ether.

It is to be understood that not all of the solvent species give the same degree of performance, and that discrete compounds uithin the species classi-fications do not provide the same results. It is obvious that determination of which particular solvent oil is best suitable for use depends on the application, and can be determined by experimentation. Of course, it is to be understood that the compositions of matter of this invention encompass employing a single type OL the above three defined types of suitable solvent oils (alcohol, ester, and ether), employing a mixture of two or more different oils but of the same type (e.g. two different esters) as well as employing a mixture of two or more different types of oils (e.g.
an ester and an alcohol). Generally it is preferred to employ a single type of solvent oil in a given com-position, the esters being the most preferred.

~V~30 The diluent oils of the invention are of four basic types, polyol esters (as distinct from mono-esters), phosphate esters,hydrocarbons, and polyalkylene glycol ethers. The polyol esters are condensation products of polyfunctional carboxylic acids with alcohols or alternatively, condensation products of polyfunctional ` alcohols with monocarboxylic acids. The phosphate esters are condensation products of phosphoric acid and alcohols. The hydrocarbons would include naphthenic, alkylated aro~atic, and aliphatic oils havlng an SUS
viscosity of from 30 to 5~0 at 100F. The polyalkylene 81YCol ethers e~compass adducts or alkylene oxides (e.g. ethylene oxide, propylene oxide, butylene oxide) which are "started" with mono-, di-, or trifunctional alcohols.

While the prior art discloses compositions containing dimethylsiloxane oils and compounds from each of the categories of diluent oils, or in some cases compositions of the solvent and diluent oils, the pre-sent invention, contemplates ternary compositions con-taining those diluent oils which are not compatible ~`
with the silicor.es employed herein, or whose compati-bility is markedly improved by the presence of the sol-vent oils of the invention. Given the range of vis-cosities and possible concentrations of the silicone oil component of the compositions of the invention, acceptable diluent oils include in some concentration, virtually all known compounds within the broad classi-fications of polyol esters, phosphate esters, hydro-carbons, and polyalkylene glycol ethers described above with the proviso that said diluant oils are compatible with the solvent oils of the present invention at 0 F
when mixed in the same ratio as they would appear in 9~

the ternary composition of the invention. This is to say that experimentation has shown that compatible sol-vent oils and diluent oils, when mixed, do not exhibit negative solvent interactions with respect to silicone oils, and thus that the outstanding solvency of the solvent oils provides for compatibility or improved compatibility of silicone oils with the diluent oils.
` The diluent oils tend to bring flexibility and a variety of desirable properties to the compositions o~ the invention It ls to be understood that not all of ~he diluent species give the same degree of performance, and that discrete compounds within the species classi-fications do not provida the same results. It is obvious that determination of which particular diluent oil is.
best suitable for use depends on the application, and can be determined by experimentation. Of course it is to be understood that the compositions of matter of this invention encompass employing a single type of the above four defined types of suitable diluent oils (i.e. polyol esters, phosphate esters, hydrocarbons, and polyalkylene glycol ethers), employing a mixture of two or more different oils but of the same type (e.g. two different hydrocarbon oils, and the like), as well as employing a mixture of two or more different types of oils (e.g. a polyol ester and a polyalkylene glycol ether, and the like).
Generally, it is preferred to employ a single type of hydrocarbon oil on a given composition, the hydrocarbon and polyalkyle~e glycol ether oils being the most preferred.

The silicone-solvent oil/silicone-solvent oil-diluent oil compositions of matter of this invention can be prepared in any conventional manner. Generally, the . . - . ,: :

~llV(~30 components need only be mixed together in the proportions desired while stirr~ng at room temperature, or slightly elevated temperatures. The proportions of silicone oil, solvent oil, and diluent oil in the compositions of this invention can range from 1 to 99 per cent by weight (preferably 3 to 25 per cent by weight or 75 to 95 per cent by weight) of the poly(dimethylsiloxane), and from 1 to 99 per cent by weight (preferably 5 to 30 per cent by weight or 70 to 95 per cent by weight) of ~he solvent oil, and from 0 to 98 per cent by weight (preferably 10 0 to 40 per cent by weight) of the diluent oil, with the proviso that the proportions and composition of the diluent oil are selected such that the diluent oil and the solvent oil would be miscible at 0F if mixed in the same ratio as that found in the final composition; and with the additional proviso that the ternary compositions of silicone, solvent, and diluent oils of the invention are miscible at temperatures below those at which binary compositions of the diluent oil, and an equal proportion by weight (as in the ternay composition) of the silicone oil aFe miscible.

The term "miscible" is used herein to mean that there is no evidence of separation, while "immiscible"
is used to mean that there is evidence of separation. For the purposes of this invention, the temperature at which the compositions become immiscible is determined by lowering the temperature to a point where separation is evident, and then slowly increasing the temperature until evidence of separation no longer exists. It has been determined by experiment that this method, because of the tendency of the compositions in the invention to supercool, is the only one which results in accurate readings.

110~1930 "
Of course, it is to be understood that not every possible silicone oil employable herein may be miscible with every solvent oil or blend of solvent oil and diluent oil employable herein. Likewise, it is to be understood that not every possible proportionate range by weight employable herein for every silicone oil and solvent oil and diluent oil of this invention may produce miscible compositions or give the same degree of results.
It is furthsr obvious that determination of which partlcular solvent blend is best suitable for use in the instant in-vention can be readily determi~ed by routine experimenta-tion as ~aught herein.

As evidenced by their compatibility, the com~
positions of matter of this invention have excellent viscosity-temperature, viscosity-volatility, and low temperature stability properties, low pour points, and high flash points. They may be used as lubricants, hydraulic fluids, motor oils, heat transfer fluids, transformer oils, transmission fluids, shock absorber fluids, damping fluids, textile lubricants, gear oils, mold release compounds, greases and the like. Preferably, the compositions of matter of this invention may be em-ployed as hydraulic fluids.

Accordingly, another aspect o this invention is a process for effecting movement of a movable member within an enclosing chamber, consisting of transmitting pressure to the movable member through a liquid medium comprising a composition of matter of this invention as ~`

defined above.

Of course, it is to be understood that the specific type of hydraulic system is not critical and need not be described herein. Such systems are conven-tional and well known, and the purpose of the present ~0()930 invention is not to define any particular novel mech-anical system but to describe novel compositions of matter that are useful as lubricants and hydraulic fluids.

It is to be further unde.stood that the silicone-hydrocarbon compositions of matter of this invention, if desired, can contain other conventional additives in the conventionally used quantities commonly employed in hydraulic fluids, and the like, such as antioxidant9, rusc and corrosion inhibitors, anti-wear agents, dis-persantsl and the like.

The followi~ examples illustrate the present invention:
Exa~æ~ 9 A series of compositions was prepared by blending ~-10 per cent by weight of 100,000 cs dimethylsiloxane polymer with various solvent oils of the invention. The - compositions and separation temperatures are shown in Table I. It can be seen that subtle differences in the structure of the solvent oils can make significant differences in the compat-bility of the blends, and 2a that the utility or appropriateness of a given solvent oil is best determined by experimentation.

110~)930 ll TABL& I

Separation Solvent Oil 1 90i by weight (1)) Temperature (IC) Ex. 1 Isodecyl?ropionate -30 Ex. 2 Tridecylpropionate -23 Ex. 3 2, 6, 8-trimathyl-4-nonyl- -29 propiOnate Ex. 4 rsodecyl butyrate -43 Ex. 5 Isodecyl valerate -34 Ex. 6 2, 6, a-trlmethyl-4-nonyl- ~ -51 valerate Ex. 7 2, 6, 8-trimethyl-4-nonyl -45 (2-ethyl) hexanoate Ex. a 2, 6, 8-trimethyl-4~nonyl 11.5 (3, 5, 5-trimethyl) hexanoate Ex. 9 2, 6, 8-trimethyl-4-nonanol -la (1) Co~positions also contain 10~ by weight of 130,000 cs polydimethylsiloxane.
Exa~pLes 10 - 13 A s0rles o~ compositions was prepared by blending 10 per cent by weight of various dimethylsiloxanes with tridecyloctanoate solvent oil of the invention.~ The compositions and separation temperatures are shown in Table II. It can be seen that the compa-tibility of the blends varies with the vLscosity of the silicone oil.
T~BLE_II
Separation ExampleDimethylsilicone Oil (1)Temperature C
~x. 10100,000 cs 54 `
Ex. Il10,000 cs 42 Ex. 121,000 cs 25 Ex. 13100 cs -19 (1) 10~ by weight in the composition. The remaining 90~ is tridecyloctanoate.

.

/~

Example 14 :
~ series of compositions was prepared by blending vacious weight percentagas of 100,000 cs polytdimethylsiloxane) with 2, 6, 8-trinethyl-4-nonyloctanoate. The compoiitlon9 and separation temperatures are shown in Table III. It can be seen that the compatibility of the blends varies with the concentration of the silicone oil.
TABLE III
Example Ratlo of Sil1cone~ Solvent O1~2) Tempe~ature C
Ex. 14 5 : 9S ~54 Ex. 14ta) 10 : 90 -55 Ex. 14~) lS : 85 -57 Ex. 14(c) 20 : ao -62 Ex. 14(d) ~5 75 ~-65 Ex. 14(~) 30 : 70 ~-65 (1) 1001000 cs Poly~dimethylsiloxane)

(2) 2, 6, a-trime~hyl-4-nonyloctanoate.
.

Exa~npl~s lS - 23 , A serles of composltlons was prepaced by blending various weight percentages of 2, 6, 8-trimethyl-4-nonyloctanoa~e (a solvent oil), and di~ferent diluent oils with 10 per cent by weight of 100,000 cs poly(dimethylsiloxane). Por the purpose of conPariSOn, blnary compositions of ~he diluent and silicone oils, containing a slmllar concentratlon of slllcone oll, are also presented. The compositions and separation temperatures are shown in Table IV.
Mlxtures of the solvent and dlluent oi}s are all niscible at 0P.
It can be seen that the presence of solvent oll substanti211y lmproves the compatlbility of sllicone and diluent oils, noreover it is clear from the data presented in that experimentation such as that described in Examples 15-23 is necessary for determining the scope of the invention wlth respect to ternary conpositions. ~-~1

3~J I

TABLE IV
Ratio of Sil if ~e(l) Example 31end Diluent Oil Solvent Oil : Separation Ex. 15 a Petrofin O(3) ~ 10 . 50 , 40 ~47 C 10 : 25 : 65 22 D n 10: 0: 90 62 Ex. 16 A Flexol ToFt4) 10 : 75 : 15 -47 3 n 10: 50 : 40 -20 C n 10 25: 65 3 D n 10; 0: 90 38 Ex. 17 A Phenyl docec~ne 10 : 75 : 15 -2 6 8 n 10: 50 : 4030 C " 10 : 25 : 65 76 o n 10: O: 90Immiscible ~ 3x. 18 A Solvent 100N t5) 10 : 75 : 15 -lS
! B n 10: 50 40 55 C n 10: 25 : 65Immiscible D n 10: O: 90Immiscible Ex. 19 A Alkyl 8enzene(6) 10 : 75 : 15 -50 8 '' . 10 50 : 40-39 C n 10; 25 : 65-22 D 10 : 0 : 9012 Ex. 20 A Gulf Synfluid(7)~ 10 : 75 : 15 -11 B n 10: 50 : 40 68 C n 10 : 25 : 65 Immiscible D n 10: O: 30Immiscible Ex. 21 A Z - 88(8) 10 : 75 : 15 -12 B n 10: 50 : 40 65 - C n 10: 25 : 65 Immiscible D n 10 : 0 : 90 Immi~cible Ex. 22 A Butylcarbitol(9) 10 : 75 : 15 -25 B 1 10 : 50 : 40 81 C n 10: 25 : 65 Immisclble D ~ 10 : 0 : 90 Immiscible Ex. 23 A L8_65~1) 10 : 75 : 15 -30 a n 10 50: 4090 C n 10; 25 : 65 Immiscible D n 10 : 0 : 90 ~mmiscible Trade ~ark . . , / , , , .. .
~ ., .

:: -3(~ 1 TABLE_IV ~cont'd) (1) 100,000 C5 ,oolydimethylsiloxane.
(2) 2, 6, 8-trlmethyl-4-nonyloctanoate.
~3) A polybutane oil from Petrofina Inc.
~4) Tri ~2-ethyl) hexylphosphats.
(5) A paraffinic hydrocarbon oil supplled by Imperial Oil of Canada Ltd.
(6) A i'raction Oe a qample supplied by Chevron Co.1 tha alkyl sub tituent is a hlghly branched hydrocaebon of from 9-15 ~7) A ?lY l-decane suppllad by Gulf Oil Co~p.~ ~4 C5 at 100F.
~a) Oi (2-qthyl) hexyl a~late, suppliQd by Unlon Carbide ~9) C4HgO~C2H40)~ a glycol ether supplied by Union CarbLde Corp.
~10) A polyalkylene oxide adduct supplied by ~nion Carbide Corp.

Examples 24 -_~Q__ A series oi compositions was prePared by blending various weight percentages Oe 2, 6, ~-trimethyl-4-nonyloctanoate ~solvent), diluent, and low viscosity silicone oils with 10 per cent by weight of 100,000 cs poly(dimethylsilo~ane). The compo-sitions and separation temperatures are shown in Table V. It can be se~n that for solutions of a given weight per cent Oe high viscosity silicone oil, the presence of a portion of low viscosity silicone oil substantially increases the compatibility of the compositions.
The foregoing data and discussion serve to reveal the exceptional properties and cha,acteristics of the eunctional eluid compositions of the invention. For use in extreme and rigorous environments, functional fluids are required which possess P~oper-ties such as those exhibited by compositions Oe the invention.
The specific details Oe the compositions desc,ibed with referenca to the above examples are for the purpose of illustrat-ing the invention. ~odification in the incidental eeatures and -~
details of the composition including the addition Oe othe, additives for speciEic functions can be made without departing from the spirit and scope of the applicant's invention.

_, 9~(~

o~
V ~ O U~ ~ ~ N
O. Q. v ~p ~

_ U~
l~l o ~ O r~ o O~ O N O
O N ~ o O O
_ .... .... " _,.
a ~ , N N N N ~O Ol W ,...... .. ~w ..... ..
O O O O O O e~ O O O O
O
V ..

CO
E ~, ", ~
3 a~I 0O Q~ ~IJ0 UO
W~ "_. o ~ o ~ 00 o o o P 0 o~~ oO o o 3 oO o o o o o . .
,--S U~ _ C1 ,o~ o V
e Q Q O O

_ Q ~, Q ID O
,0~ C
_ --a ~ e _I O O ~ '1:1 0 0 N N O O O 1ll 111 ~
v v v _ 5 Q ~ ~ E ' E E E
O O ., >,o o_1 " O o ~ a O ~
_ o o 3 c " ~ _ ~ o ~ ol 0 0 0 v 0 Cl Cl) u~ o ~: 3 5 ~o ol C ~1 51 É EO :> EO
' ~. U~ ~ U~
ol ~ ~r ~ .or- r~ ,I r~ ~ ~ ~ r. co r.
N N r~ ~ r~ C~
i X X X X . X

-- 18 ~

.':,, ' ' '`-`, '`

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A lubricating oil composition comprising a homo-geneous mixture of from 1% to 99% by weight of:

(A) a poly(dimethylsiloxane) selected from the group consisting of those having the general formula:
R3SiO(R2SiO)xSiR3 and wherein R is methyl and x is an integer having an average value that corresponds to the viscosity of said poly(dimethylsiloxane), said poly(dimethylsiloxane) having a viscosity of from 5 to 1,000,000 centistokes at 25°C; and the remainder of said mixture consisting of:

(B) a solvent oil selected from the group consisting of:

( i)Branched chain alcohols having the general formula:

( ii)Monocarboxylic acid esters of branched chain alcohols having the general formula:

and (iii)Homologous ethers having the general formula:

...2 wherein R1=CkH2k+1, R2=H or CiH2i+1 and R3=H or CmH2m+1 and wherein 8?(k+i+m)? 18 and the longest chain formed by R1, R2 and R3 contains 2 or more substituent alkyl branches and R4=H or CnH2n+1 and 1?n?12.

2. A composition as claimed in claim 1 comprising a homogeneous mixture of from 5% to 30% by weight of (A) and from 95% to 70% by weight of (B).

3. A composition as claimed in claim 1 comprising a homogeneous mixture of from 75% to 95% by weight of (A) and from 25% to 5% by weight of (B).

4. A composition as claimed in claim 1, comprising a homogeneous mixture of 10% by weight of (A) and 90%
by weight of (B).

5. A composition as claimed in claim 2, 3 or 4 wherein (B) is one selected from the group consisting of 2,6,8-trimethyl-4-nonanol, 2,6,8-trimethyl-4-nonyl octyl ether, isodecyl pentyl ether, 2,6,8-trimethyl-4-nonyl octanoate, isodecylvalerate and tridecyloctanoate.

6. A lubricating oil composition comprising a homo-geneous mixture of (A) from 1% to 10% by weight of a poly(dimethylsiloxane) selected from the group consisting of those having the general formula:

R3SiO(R2SiO)xSiR3 and wherein R is methyl and x is an integer having an average value that corresponds to the viscosity of said poly (dimethylsiloxane), said poly(dimethylsiloxane) having a viscosity of from 5 to 1,000,000 centistokes at 25°C;

...3 (B) from 1% to 75% by weight of a solvent oil selected from the group consisting of:
( i) branched chain alcohols having the general formula:

( ii) monocarboxylic acid esters of branched chain alcohols having the general formula:

and (iii) homologous ethers having the general formula:

wherein R1=CkH2k+1, R2=H or CiH2i+1 and R3=H or CmH2m+1 and wherein 8?(k+i+m)?18 and the longest chain formed by R1, R2, and R3 contains 2 or more substituent alkyl branches and R4=H or CnH2m+1 and 1?n?12;
the remainder of said mixture consisting of:

(C) a diluent oil selected from the group consisting of hydrocarbon oils, polyol esters, phosphate esters and polyalkylene glycol ethers.

7. A composition as claimed in claim 6 comprising a homogeneous mixture of from 1% to 10% by weight of (A) from 25% to 75% by weight of (B) and the remainder consisting of (C).

21 ...4

8. A composition as claimed in claim 6 comprising a homogeneous mixture of from 1% to 10% by weight of (A), from 5% to 25% by weight of (B) and the remainder consisting of (C).

9. A composition as claimed in claim 6, 7 or 8 wherein (B) is one selected from the group consisting of 2,6,8-trimethyl-4-nonanol, 2,6,8-trimethyl-4-nonyl octyl etber, isodecyl pentyl ether, 2,6,8-trimethyl -4-nonyl octanoate, isodecylvalerate and tridecyloctanoate.