CA1100931A

CA1100931A - Oil compositions containing high and low molecular weight poly(dimethylsiloxane)

Info

Publication number: CA1100931A
Application number: CA314,317A
Authority: CA
Inventors: William C. Morro; Donald E. Rathgeber
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

OIL COMPOSITIONS CONTAINING HIGH AND LOW
MOLECULAR WEIGHT POLY(DIMETHYLSILOXANE) ABSTRACT

Compositions useful as lubricants or hydraulic fluids are described which consist of a hydrocarbon oil having a Saybolt seconds universal viscosity at 100°F
of from 30 to 500 and a flash point greater than 175°F
blended with a mixture of a low viscosity poly(dimethylsiloxane) having a viscosity of from 5 to 1000 centistokes at 25°C
and a high viscosity poly(dimethylsiloxane) having a viscosity of from 10,000 to 1,000,000 centistokes at 25°C.

Description

)93~
This invention relates to compositions of matter use~ul as lubricants and hydraulic fluids and more particularly to hydrocarbon oil compositions blended with low and high viscosity poly(dimethylsiloxane) for use as lubricants and in hydraulic systems in low temperature conditions.

Lubricating oil compositions are often em-ployed as functional fluids,transmission fluids, or heat transfer fluids, such as in au~omatic transmlssions, pumps, and hydraulic equipment. Hydraulic fluids having a good viscosity-temperature, viscosity-volatility, and stability characteris~ics are very desirable. Por 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 extre~e experienced and yet be low enough to flow freely at the lowest temperature expected.

It is well known that certain liquid poly-(org~nosiloxanes) exhibit a very high viscosity index

2~ which enables them to be used as functional fluids over a broad temperature range. Poly(dimethylsiloxane) in particular, shows a performace in this area which is superior to virtually all known materials. Unfortunately, these so-called silicone oils, especially poly(dimethylsiloxane) are incompatible with most other materials and are economically unattractive; moreover, they have poor lubricatin~ properties when used as lubricants for metal on metal, particularly steel on stee~ applications.
Their incompatibility makes it difficult to improve their performance with additives.

~ .' In order to take advantage of the good - viscosity-temperature properties of silicone oils, it is desirable to dissolve them in lubricating oil carriers.
This has been carried out with various poly(organo-silo~anes) as described in German Patent 1,800,44~.
However, the solubility characteristics of poly-(dimethylsiloxane) generally prevent iCs dispersion in liquid media, excepe ~ith 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-(dimetbylsiloxane) oil has been succassfully incorporated nto a homogeneous compositlon, the molecular weight of the sillcone has been such that its viscosity has been limited to around 1,000 cs or less as shown in U.S.
2,652,364 and U.S. 2,618,601.

~ore recently, mlxtures of hi8h molecular weight (high viscosity) dimethylsiloxane polymers and selected iso-paraffinic, naphthenic, and unsaturated alipha~ic hydrocarbon oil solvents, as disclosed in U.S.Patent 4,0;9,534 issued November 21, 1977, have been proposed for use as multi-purpose lubricants and functional fluids.
Iu addition, hydraulic fluid compositions comprising a low viscosity dimethylsiloxane oil and a hydrocarbon oil component selected from the group of naphthenic oils, branched chain aliphatic hydrocarbon oils and alkylated aromatic oils for use as lubrlcants and hydraullc fluids ~ ~-are dlsclosed in U.S. Patent No. 4097393 issued June 27, 1978 while compositions comprising poly(dimethylsilo~ane) 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 in Canadian Application 273,020. However, none of the above applications disclose the compositions of the instant ir.vention. Moreover, most of the above compo-sitions have the disadvantage that their compatibility ~L0~93~

~1~0~3~L
is limited by temperature, and thus they are unsatis-factory for use where relatively low temperatures are encountered.

It has now been discovered that silicone hydrocarbon compositions oE matter can be prepared, which are useful as lubricants and hydraulic fluids, having excellent viscosity-temperature characteriscics and low temperature stability.

It is therefore an object of this invention to provide a novel silicone-hydrocarbon compositionsof matter which are usefu:L as lubricants and hydrocarbon fluids.
More particularly, this invention may be described as a composition of matter consisting of from 2% to 98% by weight of:
(A~ a high viscosity poly(dimethylsiloxane) of the general formula:
R3SiO(R2SiO)XsiR3 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 lO,OOO to 1,000,000 centistokes at 25 C; the remainder of said mixture consisting of (B) a solvent blend of from 1% to 99% by weight of ( i) a low viscosity poly(dimethylsiloxane) selected from the group consisting of the general formula:
R3SiO(R~SiO)xSiR3 and ~ O-(R2siO)XR2si-.;

wherein R is methyl and ~ is an integer having an average value that corresponds to the viscosity of said poly(dimethylsilo~ane)~
said poly(dimethylsiloxane) having a viscosity of from 5 to 1,000 centistokes at 25C; and the remainder of said solvent blend comprising:

(ii) a hydrocarbon oil miscible at 0F. with (i) and having a Saybolt seconds universal viscosity at 100 F of from 30 to 500, a flash point greater than 175F, sald hydrocarbon oil '~
being at least one selected from the group consisting o~ naphthenic oils having a viscosity gravity constant of at least 0.84, alkylated aromatic oils and branched chain aliphatic hydrocarbon oils.

It is another object of the invention to ,~
provide a process for effecting movement of a moveable -member within an enclosing member which comprises trans-mitting pressure to said moveable member through a liquid medium consisting essentially of a lubricating oil com-position as defined above.

It is still another object of the invention to provide a process for transmitting force through an hydraulic system having hydraulic activating means, an hydraulic line means connecting 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 activated means with a lubricating oil composition as defined above. Other objects and advantages of the inven-tion will become readily apparent from the following description and appended claims.

3~

1~0~)~3~
Descriptlon_ot ~he Embodiments ~ he high viscosity dimethylsiloxane oil~ employed in this invention as well as methods for their preparation are well known and consist essentially of siloxy units of the formula R2SiO and end-blocking siloxy units of the formula R3SiOo 5 ~herein R is a methyl radical. As ~mployed herein such siloxane oils are essentially linear siloxane polymers havin~ a viscosity in the range of about 10,000 to about 1,000,000 centistokes (cs) at about 25 C preferably about 60,000 to about 500,000 centistokes (cs) at about 25C, and most preferably about 60,000 to about 100,000 centistokes at about 25 C. These siloxane oils are also conventionally represented by the average formula E~3SiO(R2SiO)XSiR3 wherein R is a methyl radical and x is an integer having an average value that corresponds to the viscosity of the particular siloxane.

It is to be understood, of course, that while the high viscosity 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 produce a final mixture of relatively narrow molecular weight distribution, due at least in part, to the fact the starting materials used to produce the siloxane oils are themselves usually mixtures. Thus, it is 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 hi8h viscosity silicones specified herein may be used, and that t'ney may in some cases improve the properties in a manner consistent - with the trends identified in the following examples.

.

9~
The solvene mixtures employed ~n this invention are either well known or obvious from the prior art, and con3is~ essentially of (ii) hydrocarbon oils and (i) dimethylsiloxane oils. The dimethylsiloxane oils employed in the solvent mixture are of low viscosity (low molecular weight) and, as established in U.S. Patent 4,059,534 issued November 22, 1977, are distinct from the poly-(dimethylsiloxanes) of high viscosity, as evidenced by their chemical structure, solubility, and such physical properties as viscosity, pour point, and flashpoint.
As employed herein such low viscosity siloxane oils have a viscosity in the range of from about 5 to 1,000 centistokes at about 25 C, and preferably from about 10 to 500 centi-stokes at 25C, and most preferably from about 10 to 100 centistokes at 25 C. They are selected from the class consisting of linear polymers consisting essentially of siloxy units of the formula R2SiO and end-blocking siloxy units of the formula R3SiOo 5 where~in R represents a methyl radical, and cyclic polymers consisting essentially of siloxy units of the formula R2SiO, wherein R represents a methyl radical.
These siloxane polymers are also conventionally represented by the average formulae R3SiO(R2SiO)XSiR3' and ¦--(R2Si)x-R2sil respectively, wherein R 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 trime~hyl end~blocked dimethylsiloxane oil having a viscosity of 100 centistokes at 25 C can be represented as having the average formula Me3SiO(Me2SiO)48SiMe3 wherein ~e is a methyl radical.

It is to ~e understoocl, of course, that while the low viscosity dimethylsi~oxane oils used in this invention can be discrete chemical compounds, they are usually com-prised 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 silo~ane oils are themselves usualLy mixtures. Thus, it is 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 low viscosity silicones specified herein may be used, and that they may in some cases improve the properties in a manner consistent with the trends identified in the following examples.

These low viscosity silicone oils comprise from 1 to 99 per cent by weight, and preferably from 5 to 90 per cent by weight, and most preferably from lO to 40 per cent by weight or 60 to 85 per cent by weight of the solve-nt mi~ture.

As employed herein, the hydrocarbon oils of the solvent mixture must be miscible at 0F with the low viscosity silicone oil employed in said solvent mixture.
The hydrocarbon oils have a Saybolt seconds universal viscosity at 100 F of from 30 to 500, flash points of greater than 175 F, and may be of either synthetic or natural origin. Such hydrocarbon oils are, for the most part, identified in the prior art, and may be selected from the class consisting of naphthenic oils having a viscosity-gravity constant of at least 0.84, alkylated aromatic oils, and branched chain aliphatic hydrocarbon oils.

~61931 Naphthenic oils that can be empLoyed in this invention have a viscosity-gravity constant of at least 0.84 and may be refined petroleum distillate frac~ions containing large ?roportions of naphthene ring carbons, i.e. 30-45 C naph~hene. Generally such naphthenic petroleum oil fractions will have aniline points ranging E~om 135 F to 185 F indicating a significant number of aro~aeic carbon atoms, i.e. about 10 to 30~ C aromatic. They are well known in the art and are normally obtained by the conven~
tional refining of fossi~ or synthetic crude olls (e.g.
United States Southwest and Coastal naphthenic crudes), by atmospheric and/or vacuum distilla~ion followed by solvent and/or hydrogen refining and solvent or low temperature solution dewaxing, if desired. Illustrative of the more pre~erred refined petroleuM naphthenic oils that can be employed herein are those commercial oils like '7Calumet"*of the Calumet Refining Company, "Circosol"*
of Sun Oil Co., and "Necton"~oils of th~ Exxon Corporation, and the like.

The naphthenic oils of the invention may also be of syathetic origin, and may be produced by a wide variety of means known to those with skill in the art.
Illustrative of the more preferred syn~hetic naphthenic oils that can be employed herein are cyclohe~ane started alkene oligomers having at least one alkyl substituent ;
which exceeds four carbon atoms, and no single alkyl substituents which exceed about 20 carbon atoms.

~lkylated aromatic oils that can be employed in this invention are synthesiz~d aromatic hydrocarbon oils.
Such alkylated aroma~ic oils are well known and are nor-mally obtained by the alkylation of selected aromatic - intermediates, e.g. by conventional alkylation via the well known Friedel-Crafts reaction. Illustrative alkylation - agents are alphaolefins, chlorinated alkanes, alcohols, and the like having up to 24 carbon atoms. Illustrative * Trade Mark llOQ93~ 9 ~0(~93~
aromatic intermediates are benzene, alkyl-substituted benzenes, e.g. toluene, xylene, propyl substituted benzenes, butyl substituted benzenes, di-lauryl benzene, di-(mixed Cll to C15alkyl) 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 aromatic mixture residues obtained in the commercial production oE detergent alkylates. Other illustrative aromatic intermediates are naphthalene and various alkyl substituted naphthalenes where the alkyl group contains from 1 eo 4 carbon atoms, e~g. methyl naphthalene, di-and tripropylnaphthalene, di-, tri- arld 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 alkylated benzenes, obtained in the production of detergent alkylates such as commercial oils and residues manufactured by the Chevron Chemical Co., wherein propylene trimer, tetramer, and higher polymers are used as alkylating agents.
The branched-chain aliphatic hydrocarbon oils that can be employed in this invention are well known alkylates boiling in the preferred range of about 400 F to 700F.
The most readily available source of branched-chain hydro-carbon oils that can be employed in this invention are mixed isoparaffin-naphthene hydrocarbon stocks obtained by the appropriate refining of petroleum fractions boiling - 30 within the range of about 400 F to 700 F 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 ~)093~
by conventional means, if necessary, (b~ selective de-aromatization by treatment with sulfuric acid or a catalytic hydrogen treatment, and (c) filtering using an ordinary clay-type filter media.

They can also be produced by the conventional processes of alkylating C2 to ~5 olefins with isoparaffins containing a tertiary carbon atom having 3 to 6 carbon atoms such as isobu~ane. They may also be prepared by the polymerization, of selected olefins such as C2 to C12 mono-olefins selected from the group consis~ing of alpha-olephins and various internal 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 good low temperature ~-flow characteristics. ;

It is, of course, to be understood that the polymerization products of the olefins, commonly known as oligomers, include both the unsaturated oligomers as 20 well as the corresponding saturated (hydrogenated) oligomers. ; :-~ It is also to be understood that, if desired, in addition - to employing a single type of olefin oligomer mixtures of two or more different olefin oligomers can be employed, just as it is obvious that a single olefin or mixture of different olefins can be used in the preparation of said olefin oligomers, in certain polymerization processes.

As pointed out above, the aliphatic hydrocarbons of the invention should be branched, and, in the case of the synthetics, the degree and type of branching can be - 30 selected so as to optimize the solubility and physical properties. U.S. patent 4,059,534 issued November 22, 1977 indicates that such hydrocarbons should be highly branched and should have exceptional low temperature properties in order to be compatible with high viscosity silicone oils of the invention, and co be useful for their specialized function. For the purposes of this invention, the aliphatic hydrocarbons need not be so restric~ed. They need only be compatible with the low viscosity silicone oil of the solvent blend at 0F in order to be useful, and thus, while it is ?referred that there be a hi~h degree o- branching, and that substituent alkyl branches be limited to four carbons in length, said aliphatic hydrocarbons are not restricted to such a structure. Further, the pour point depressant effect of the low viscosity silicone olls of the solve~t blend, as disclosed in "Viscosities o~ Mixtures of Polysiloxanes wlth Synthetic Liquids of Other Classes", .I. Volchins~aya, et al., Tr., Vses. Nauch. - Issled.
-Inst. Pererab. Nefti, 1970, No. 12,320-4, and "Anomalous Viscosities of Mixtures of Oils of Different CO~pOSitiQnS", D. S. Velikouski and B. I. Kazhdan, Materialy Mezhvus, Sovenshehaniya po Voprosam Novoi Tekh. v Neft. Prom. 1958, No. 2, 245-9, allows the use of hydrocarbons with good, rather than exceptional low temperature properties.

Illustrati~e of the petroleum derived aliphatic compounds of the invention are commercial isoparafrir.ic oils such as "Exxon 3146"*and "Exxon 3147"*of the Exxon Corporation,USA. It should be poin;ed out that oils of this type are not exclusively isoparaffinic, i.e. they contain -' substantial quantities of naphthenic rings and, in some cases, minor propor~io~s of aromatic rings. It is known, however, that isoparaffinic hydrocarbon mixtures with ~-relatively small proportions of cyclic structures can be made by the separation of the branched chain or isoparaffinic portions of mixed branched chain/straight chain hydrocarbon mixtures, as e.g. the hydrocarbon fraction o~ conventional petroleum kerosene fractions. Such separations may be made by the use of selected zeoli~e clays. e.g. Molecular Sieve SA produced by the Linde Division of Union Carbide Corporation. ~dvantage may also be taken of the ability * Trade Mark ~93~ - 12 -of n-paraEfins co form addition products with urea or thiourea to effect the separation of branched chain and straight chain aliphatic hydrocarbons. Preferred examples of petroleum distiilates corresponding in large me~sure to this description include Esso Uni~lolt 4~, and Imperial Oil Isopar*products. Illustrative examples of synthetic branched-chain hydrocarbon oils are polypropylene, C15 to C30 carbon atoms, polyisobutylene, C12 to ~C40 carbon atoms ("Oppanol B-~ of Badische Anilin und Soda-Fabrik, AG.), as well as 2, 2, 4, 4, 6, 8, 8-heptamethylnonane, 2, 6, 10, 14-~etramethylpen~atecane, and oligomers of l-decene such as the "Syn fluids'~ of Gulf Oil Che~ical, Co. Preferred examples would include saturated and unsaturated oligomers of C3-C6 olefins.

As pointed out above all three types of hydro-carbon oils employed in this invention are characterized by their flash point and their Saybolt seconds universal viscosity at 100F, (Ssu), while the naphthenic oils are further characterized by their VG5 (viscosity-gravity constant). The flash point is measured by AST~ test method D92, while the Saybolt 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. ~ill and H. B. Coats in "The Viscosity-Gravity Consta~t of Petroleum Lubricating Oils", Industrial and En~ineering Chemistry, June 1963, p.641 a~d is now a widely accepted procedure for the approximation of the degree of aromaticity or para~finicity of a hydrocarbon.

The viscosity-gravity constant employed herein is de~ermined by ASTM test method D-2501-67 published in the 1973 Book of the American Society for Testing and Materials, Part 18.

The VGC is relatively insensitive to molecular weight and is related to the proportion of naphthenic and arom2tic structure in the oil. Values of VGC near 0.800 indicate a paraffinic character, where values close to 1.00 indicate a preponderance of aromatic structures.

~-) * Trade Mark 110~93~

Of course, it is understood that the compositions of matter oF this invention encompass employing a single type of the above three defined types of suitable hydro-carbon oils (i.e. naphthenic oils, alkylated aromatic oils and branched~chain aliphatic hydroc~rbon 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 aromatlc oil, and the like). Generally it is preferred to employ a single type of hydrocarbon oil in a given composition, the branched aliphatic oils being the most preferred.

The silicone-hydrocarbon compositions of matter of this invention can be prepared in any conventional manner.
Generally~ the three components, two comprising the solvent medium plus the high viscosity silicone polymer, need only - be mixed together in the proportions desired while stirring at room temperature, or slightly elevated temperatures.
The proportions of high viscosity silicone oil to solvent blend in the compositions of this invention can range from - about 2 - 98 per cent by weight of the high viscosity ; silicone (A) ~referably 5 to 50 per cent by weight) to about 98-2 per cent by weight of solvent mixture, (B) with the proviso that said proportions of the silicone oil and the solvent blend are selected such that the two components remain miscible at temperatures below that at which the high-viscosity silicone oil and the hydrocarbon, if mixed in the same proportions as the silicone oil and the solven~ blend, would become immiscible.

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 (19;~L
t~e 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 oE the tendency of the compositions in the invention eo supercool, is the only one which results in accurate readings.

Of course, it is to be understood that not every possible solveat blend employable herein may be miscible ~ith every high viscosity silicone oil employable herein. Moreover, it is to be understood that not every possible solvent blend employable herein may be miscible with every high viscosity silicone oil employable herein at temperatures below that àt which the hydrocarbon of the solvent blend if mixed with the high viscosity silicone oil, in the same proportions as the solvent blend, would be miscible. Likewise, it is to be understood that not every possible proportionate range by weight employable herein for every silicone oil and solvent blend component of this invention may give the same degree of results. It is further obvious that determination of which particular solvent blend is best suitable for use in the instant invention can be readily determined by routine experimentation as taught herein.

It is to be understood that the addition of so-called medium molecular weight (1,000 cs - 10,000 cs) silicone oil3 to compositions of the invention may be made without departing from the spirit and scope o~ the invention.
It is a logical extension of the information included herein, that such additions may in some cases improve the properties of the co~positions slightly. They do not, however, represent a substantial improvement over the prior art, and thus we have not sought to include them within the specific claims.

As evidenced by their compatibility, the silicone-hydrocarbon compositions of m~tter 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 silicone-hydrocarbon compositions of matter of this invention may b~ employed as hydraulic fluids.

Accordingly, another aspect of this invention is a process for effecting movement of a moveable member within enclosing chamber, consisting of transmitting pressure to the moveable member through a liquid medium comprising a silicone-hydrocarbon 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 conventional and well known, and the purpose of the present invention is not to define any particular novel mechanical system ~ut to describe novel compositions of matter that are useful as lubricants and hydraulic fluids.

It is to be further understood 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 antioxidants, rust and corrosion inhibitors, anti-wear agents, dispersants, and the like.

The following examples illustrate the ~resent invention.

~ g 3 1 - 16 -Examples l 8 To illustrate the advantage of compositions of the invention over compositions comprising quantities of high molecular weight poly(dimethylsiloxane) and various hydrocarbon oils of the solvent blends, several composi-tions were prepared. Table I shows the separation temperatures and compositions of the blends. By com- ' paring the separation temperatures of analogous compositions, it is readily apparent that those formulated with the solvent blend have great advantages over chose formulated only with hydrocarbons. This is the most simple test for determining iE a given composition is within the scope oE the invention.

~.~0~9;~L

C ~
V~ oooo o~ oo oo oo oo oo ~ ~ c~ oor~ o0~ o~ cr~
~ ~ l l l l l ll l l l l l l l l l ~ Q~ ~ ~
~n ~ .~ .

o ~ ~; U~ ~
P~ ~ o o, o o o o o ~ o ~ o ~ o ,, o ~ `C ~^
~o ~
E
, DO O
C~

E

O ~ U C~ U ~ U C~ t~
~rl O OO O O O O O O O O O O O O O h U~ O OO O O O O O O O O O O O O O C
O OO O O O O O O O O O O O '~
O OO O O O O O O O O O O O O O
v U'7 u~ O O o Ou ) u) ~1 ~ O ,0 ,,~ ,0 ,0, ~ r ?~
1 ~ a~
;- ~ U'~ U~ O O ~ t~lU~ Ir) U~ Lr~ In Lr) O O U) Lr) . O ~rl O a 'D ~
': rl ~ o ~ U~ . CO
v o 4~ c a ~1 .
~rl O rl CO ~ O
. 0 O~ ~~ 3 :~ ~ D.
a u) u~ ta bq u, ~qu~ ~g o c ^ ~57 t8 h ,_, ~x ~, " v ~ a :- ~D O OO O O O O O O ~~ ~ C
~ a~ ,1 ~ ~~ o ~ ~ ~ ~ o ~ a : ~3 a ~-~ ~ c ~ c~ 3 a X v ~ ~ ~ D ~rl ~1 o ~U r o E ~ . ~ ~ ~ ~ ~ ~ h ~ t~ C q) ~ LQ C~ O U~ t~V ~) rl C
:, ~ p:l O g ~o a c s~ n' g C) a~
to ~ rl h ~
~ O .IJ ~ CJ
v C h O
_~ h ~ ~rlO ~ ~ Eo v ~ -:
e o v c~
c c c c a ca a a a ~ a ~ O rJ ~ a ~:: C~ VC) Oai ~)Ql ~ tU a~ ~ Cl ~1 ~--It.l~1 _ I C C D
O ~1 ~I r~ 1 N N~1 --1 0 0 Ch Q) al ~
D~ ;~ CD C X
o o.o o ~ ~:q C a ;~ ~ a o a~ ~ o h ~ ~ ~~ ~ ~ ~ a c~ ~ D ~ O t.) ~
~ O OO OO O O OO O~1 --1 Ch Chv L I C) O ~ C~. C~ n) Ll :~ Cl ~ ~ ~ 1~ 4 ¢ ¢ O O
~ ~ ~ C
u) o o ~ o ul o In oo o ~ o ~ x ~ r~
i~ U~Ir~ ~CS~ ~ I~ U~ I_ ~I~ U~ ,~ 0 1` U~ ~ O O ~ O
aCh QJ ~ .IJ
' C ~h ,_1 ~ ~. a~
~_ ~ ~ ' C O
;~ z ~ z ~ z ~ Z ~ P-~ r-l r-i a) ac) .~
r-l r-l ~1 _I .LJ ~ :
a~I ~c~ ¢ ~ ~

As discussed above, not all compositions of the components of the invention give the same degree of results and, in fact, not all compositions of said components have separation temperaures below the separation temperatures of analogous mixtures of the hydrocarbon and high viscosity siloxane components. In the latter case, compositions of components of the invention are not included in the inven-tion. By means of the following example, we seek to illus-trate a method of determining the scope of the invention as well as the composltions oE the invention most suitable for a given application.
- Examples 9 - 29 The trends relating to the degree of performance are clearly shown by plotting, the separation temperature against the concentration of the high viscosity silicone oil along lines of constant L (L~0), where L is the ratio of (a) the concentration of the low viscosity dimethyl silicone oil in the final composition to (b) the concen- -tration of the high viscosity dimethyl silicone oil in the final composition; the viscosity of the silicones and the nature of the hydrocarbon do not change. The scope of the invention can be determined by plotting the separation temperatures for binary mixtures of the same hydrocarbon and high viscosity silicone on the same coordinate system, a lina of constant L = 0. This has been done for the com-positions of Examples 9 - 29 (Fig. 1). Those compositions and separation temperatures are shown in Table II.

It can be seen from Figure 1 that for high values of L, the separation temperatures will generally be below those of the analogous binary hydrocarbon-silicone composi-tions, and that for low values of L, the separation temperatures will, for high concentrations of (A) high viscosity poly-(dimethylsiloxane), coincide with or be greater than those of the analogous binary compositions. Experiment has shbwn that once separation temperatures described by the lines of 3~ - 19 ~L009;:~
constant L~L~.~0) meet or exceed those of the analogous binary compositions described by L = 0, that for higher concentrations of (A) high viscosity silicone oil, the composition will not demonstrate improvement over the analogous binary compositions and thus are not within the scope of the invention.
It is to be understood that the boundaries of the invention, as illustrated by Figure 1 for one hydrocarbon, high molecular weight silicone, low molecular weight silicone system, are not readily predictable from conventional solubility theories and the mathematical techniques associated ~herewith.
Accepted polymer solution theory predicts that com-s patibility of ternary systems is a function of the weight average molecular weight (W.H. Stockmayer, J. Chemical Physics, 17, 588, (1949)), and that com-patibility may be improved throughout the concentra-tion range of high molecular weight polymer fraction simply by lowering the weight average molecular weight of the polymer-components, i.e., increasing the concen-tration of the low molecular weight (viscosity) fraction.
It is generally accepted, however, that the event and extent of improvement varies from system to system, and is accurateIy ascertained only by experimentation as described herein. The limited range over which improve-ment is shown, as illustrated by Figure 1, demonstrates that for the poly(dimethylsiloxane) - hydrocarbon com-positions disclosed herein, improved compatibility does not necessarily accompany the lowering of the weight average molecular weight of the polymer components, and that in those cases where the separation temperature is lowered, the effect is unexpected and provides a sub-stantial improvement over compositions contemplated by the prior art.

0093~L
o .,, ~
ooooooooooooooooooooo u~ I~ o o co c~ o o o co ~ ~ ~ ;r co o o co `D
~;
U~

,~
,~
U~
;~ X
o o ~
o .,, ..
o U~
A ~¦ ~
O ;~'1 U'l O _ ~ i~ ~! ~ i~ ~ 1~ ~ ~ ~ ~ àY ~ ~ ' ~e ~ o~ o~ o~! ~
~ U~ O O O O U') U~ U'l O ~I O O U~ O O U~
111 ~ ~ U--~ ~0 ¦~ CO C~ CO ~1 ~
E~
3 ~r~
:~
:I:

O
P

,_ a~
~ ~ ' X
,_ O
U7 .-1 t~
U~
O ~1 C~O ~ U~

~ ~ ~ ~ ~ cr~ l o o u~ o o u~
H I~J -1 ~1 .--1 ~I t~l t~ `J ~ ~1 , ~cr~
~1 ~ ~ ~1 ~~,A, ~_ ~ L I
¢ a.-~ rJ
Q O X~E
13 ~ F~
~C ~ C

C
r~ O
_ ~1r,~
r"~ r~q, O r,~ r~
5~ ~ U~ O O o o O ~ ~ o CO ~o ~ ~ U~ o o o al cs~ I~ ~D u~ ~ '.~1 '.`1 'J~ 1-- LO ~ '.~ cr~ cc~ n ~ r,~
CJ 1.. 1 X
O 'I~
O '~
~ Our.~
:~: ~r~
r-l C
O O
~ U~
'" U~ ~ O
~:: X
~ ~ r,~l r,~ r,~l r,~l r,~l o O O o r~ r~ O O O
3 3 O O O O O O O O O O O O O O r~ I r~ r~ r-l r~
~ ~ rj :5 ~"E,~3 r'.~

~ r~
r~J
_i r,~ O ~ r.~l r.~ o ~ CO C;~ O r-l ~ r.~ ~ D 1~ CO C71 ~-~ r-~Ir~lr~,-1r~r-lr-lr~ lr.~ lr.~lr.~lr.~ r.~lr.~
~ . ~1 ..
X X X X X X X X X X X X X X X X X X X X X X O
Z

Examples 30 - 33 A series of hydrocarbon-silicone compositions was prepared in which ~he proportion by weight of the high viscosity silicone oil was 25 per cent, and that of the solvent blend was 75 per cent. The solvent blends con-sisted of 50 per cent by weight of a propylene oligomer fraction and 25 per cent by weight of various low vlscosity dimethylsiloxane oils. The high viscosity siloxane has a ViscQsity of about 750,000 cs at 25C. Table III gives the viscosities of the silicone oils of the solvent blends, and the separation temperacures of the compositions. It can be seen that the separation temperatures tand to decrease with the viscosity of the sllicone oils of the solvent blends, and that the separation temperatures are significantly below those of the analogous blend of ; Example 30 where no low molecular weight silicone component ` is present. Clearly for systems of a given hydrocarbon, high viscosity siloxane, and L(L~O), the viscosity of the -lo~ viscosity siloxane is important in determining the 20 scope of the invention; moreover, the effect of the ;~
viscosity is seen to be easily measured by experimentation.

TABLE III

Examples 30 - 33 (5) LMW HMW ~750,000cs) Poly(dimethyl- Poly(dimethyl- Separation - Example Hydrocarbon(l) Siloxane Siloxane Temperature Ex.30(2) 75% C27 P.P. 25% -120C
Ex.31(3) 50% C27 P.P. 25% (10 cs) 25% -59 C
Ex.32(4) 50% C27 P.P. 25% (100 cs) 25% 380C
Ex.33 50% C27 P.P. 25% (1,000 cs) 25% -38 C

NOTES: (1) The propylene oligomer function of Example 1.
(2) Same composition as Example 1, blend M.

(3) Same composition as Example 4, blend N. ~-

(4) Same composition as Example 1, blend N.

(5) L = O for Example 30, L = 1 for Examples 31-33.

- ~L0~31 Examples 34 - 39 A series of hydrocarbon-silicone compositions was prepared in which the proportion by weight of the high viscosity silicone oil was 25 per cent, and that of the solvent blend was 75 per cent. The solvent blends consisted of 50 per cent by weight of a polypropylene fraction, and 25 per cent by weight of low viscosity silicone oil having a viscosity of 100 cs at 25C. Various high viscosity siloxanes are used. Table IV gives the viscosities of the high viscosity siloxane oils, and the separation tempera-tures of said compositions and the analogous binary composi-tions. It can be seen that the viscosity of the high vis-cosity silicone oil component has a discernible effect on the absolute separation temperature of each system and on the difference in separation temperatures between binary systems and the analogous blended systems of the present invention.

~0~3~

93~L
o ~
U
o o o o o o V ~ C~l ~ o C`l ~e ,, ,, ,, ~ CJ

~-~1 ~1 0 ~ O '~ ;

~ ~ _~ co ~(a u~
~ O~
X
o 00 00 ~,o o o o~ O
,,O O O oO O
Ulo O
': 3 ,_1 ^O O O O
5~ S~
U
e ~ ~e 0~ 0~ ~ ~
~ ~ U~
_, O

~ ~ .
:~ ~ ~
: ~ ' X ~ : :
.~ H ~ ~ O
a~l ~ I
C~ T
cq o u~
~ ~ o,i~ ~ ~
¢ _l r-l ~ u~ X E Z
E-' ~ --S C~ l ~I X
e u ~ X q~
o _ ~ .
~ o^ o O
P~
~ e e ~ a _ ~ S~ X X X X X
_ ~~ ~o ~ ~ ~ ~ o oqc~
ou~ ou~ ou~ O
~ ,1 a a ~ ~ a ~ O O O O O O
o aJ
~oOooO
e e e - a o O O O O O
~ ~ z ~ z x z aJ e e e e e E~

__ _ _ U~
~ . . E~
X X X X o Z

E~ample 40 Thus far we have established several sur-prisin~ and useful advantages of the compositions o the invention over binary hydrocarbon silicone mixtures.
By way of further illustrating the unexpectedly good compatibility of the compositions of the invention, we prepared a blend of 75 per cent by weight of silicone oil having a viscosity at 25C of 100 cs and 25 per cent by weight of silicone oil having a viscosity at 25C
of 100,000 cs. The separation temperature was -40 C, roughly the same as that of a binary silLcone hydrocarbon compositi.on of the same proportion high viscosity siloxane, i.e 25per cent by weight of 100,000 cs silicone oil, and 75 per cent by weight of a propylene oligomer fraction separating at -39C. Yet an analogous ternary composition of the invention (25 per cent by weight of 100,000 cs silicone, 25 per cent by weight of 100 cs silicone, and 50 per cent by weight of the propylene oligomer fraction), exhibits a separation temperature ofC-62 C well below those of these binary mixtures; thus the behavior of the compositions of the invention cannot be said to be obvious from the compatibility of compositions consisting only of high and low viscosit-y silicone oils.
Examples 41 - 47 .

It is a further advantage of compositions of the invention that they demonstrate improved viscosity pro-perties, particularly at low temperatures, over binary compositions of hydrocarbons and silicone oils, wherein the silicone oils are of relatively narrow molecular weight distribution and are chosen from a broad molecular weight range. This is illustrated by Examples 41- 47 for compositions having similar viscosities at 210 F. The compositions and viscosities of Examples 41-47 are shown in Table V.

~ 3~ - 25 -The foregoing data and discussion serve to reveal the exceptional properties and characteristics of functional fluid compositions containing hydrocarbon and high and low molecular weight silicone oil. For use in extreme and rigorous environments, functional fluids are required which possess properties such as those exhibited by compositions of the invention. As a final illustration of such a composition the following example is presented.

Example 48 To a composition colltaining 8 per cent by weight poly(dimethylsiloxane), (100,000 cs) and 89 per cent by weight of a solvent blend consisting of 1 per cent by weight of poly(dimethylsiloxane) (100 cs) and 88 per cent by weight of propylene oligomer, was added: 3 per cent by weight of Elco 130, and 51 ppm Krytox 143 AZ. ~ ;
The resulting composition was homogeneoùs at -65 F, and has viscosities of 15,866 cs and 10.48 cs at -65 F and 210F respectively. The formulation gave good wear properties on a Shell four-ball wear test, and performed outstandingly ~hen run in a Vickers type V-104-A hydraulic pump for 40 hours under high pressure conditions.

The specific details of the compositions described with re~erence to the above examples are for the purpose of illustrating the invention. Modification in the incidental features and details of the composition including the addition of other additives for specific functions can be made without departing from the spirit and scope of the applicants1 invention.

ELSO is a trade mark of Elco Corporation.

KRYTOX is a trade mark of E. I. DuPont de Nemours Inc.
.
~ 93~ 26 -~oas3~

u~ a~ . . . . . .
u a~ ~o ~O ~o ~D ~ `D
- ~ ~ ~ ~ ~ u~ ~

,~
U~ C~ ~D
O~O Cl~ CO
t~ ~ ~ .. . .
u~ c~l ~o ~o ~ o ~ ~
`r `
c~
~,~
r\ oo ~o u7 ~ ~~ ~~ o ~ ~
a o ~ l~ ~ ~ ~~ CO
,~
~ ~ .
~ .
C~~ I~ O o o O O O
o o ~ ~ n ~ o o u~ r~ ~ ~ oo ~ J~ o U~.
loo r~ u~ ~ ~ ~ CO .C:
o 0 ..
u~ ta U C~ ~0 ~ rl O
r~ u~ O O
U O O r1 o :~ . I O ~ o ~
~ o ~ o ~ ~ I :
:~
O
~:q ~q O ~n ¢ ~ ~ ~ ~ ~ I
_~ ~ ~_. ~ ~ U~
Z ~ i` 0 U~ ~ ~
¢ ~ .~ . . ~ . ~ 00 X ~: c~l O ~D 1~ 0 X O :C C~l C`l ~1 ,_1 Ei ~' ~3 V~
,~ ~
:~: U U
,.~ V ~rl ~ O OO O O O
:E: O OO ~J O ~ .
H U~ ~I r l _J O
~ 3 _ _ ~
::-1 ~ 3~ 0 V
~ ~e~ u~
O I~~ ~ U~ ~1 V
~e . . u ~11 O r~ ~ ~
V
~ ~ .
,_ ~ O
_~ ~0 ~ ~ C.
o O
a~ a~

U 00 Ct~ ~ 00 CO CO CO
O ~ 4~
S~ ~ ~rl ~1 O
~: h ?~
P~ ~J
o o a) c~ o c~ ~ ~ u~~ I` ~
~r ~ ~ ~ ~~ ~ ¢ v .. ... ..
XX X X X XX X

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 homogeneous mixture of from 2% to 98% by weight of:
(A) a high viscosity poly(dimethylsiloxane) of the general formula:
R3SiO(R2SiO)xSiR3 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 10,000 to 1,000,000 centistokes at 25°C; the remainder of said mixture consisting of (B) a solvent blend of from 1% to 99% by weight of ( i) a low viscosity poly(dimethylsiloxane) selected from the group consisting of 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 centistokes at 25°C;
and the remainder of said solvent blend comprising:
(ii) a hydrocarbon oil miscible at 0°F with (i) and having a Saybolt seconds universal viscosity at 100°F of from 30 to 500, a flash point greater than 175°F, said hydrocarbon oil being at least one selected from the group consisting of naphthenic oils having a viscosity gravity constant of at least 0.84, alkylated aromatic oils and branched chain aliphatic hydrocarbon oils.

2. A composition as claimed in claim 1 comprising a homogeneous mixture of 5% to 50% by weight of (A) the remainder of said mixture consisting of (B).

3. A composition as claimed in claim 2 wherein said solvent blend (B) comprises from 5% to 90% by weight of (i), the remainder of said solvent blend consisting of (ii).

4. A composition as claimed in claim 2 wherein said solvent blend (B) comprises from 10% to 40% by weight of (i), the remainder of said solvent blend consisting of (ii).

5. A composition as claimed in claim 2 wherein said solvent blend (B) comprises from 60% to 85% by weight of (i), the remainder of said solvent blend consisting of (ii).

6. A composition as claimed in claims 2, 3 or 4 wherein said high viscosity poly(dimethylsiloxane) has a viscosity of from 60,000 to 500,000 centistokes at 25°C.

7. A composition as claimed in claims 2, 3 or 4 wherein said high viscosity poly(dimethylsiloxane) has a viscosity of from 60,000 to 100,000 centistokes at 25°C.

8. A lubricating oil composition comprising a homogeneous mixture of from 2% to 98% by weight of:

(A) a high viscosity poly(dimethylsiloxane) of the general formula:
R3SiO(R2SiO)xSiR3 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 10,000 to 1,000,000 centistokes at 25°C; the remainder of said mixture consisting of (B) a solvent blend of from 1% to 99% by weight of:
( i) a low viscosity poly(dimethylsiloxane) selected from the group consisting of 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 7 to 500 centistokes at 25°C; and the remainder of said solvent blend comprising:
(ii) a hydrocarbon oil miscible at 0°F with (i) and having a Saybolt seconds universal viscosity at 100°F of from 30 to 500, a flash point greater than 175°F, said hydrocarbon oil being at least one selected from the group consisting of naphthenic oils having a viscosity gravity constant of at least 0.84, alkylated aromatic oils and branched chain aliphatic hydrocarbon oils.

9. A composition as claimed in claim 8 comprising a homogeneous mixture of 5% to 50% by weight of (A), the remainder of said mixture consisting of (B).

10. A composition as claimed in claim 9 wherein said solvent blend (B) comprises from 5% to 90% by weight of (i), the remainder of said solvent blend consisting of (ii).

11. A composition as claimed in claims 8, 9 or 10 wherein said low viscosity poly(dimethylsiloxane) has a viscosity of from 10 to 100 centistokes at 25°C.

12. A composition as claimed in claim 9 wherein said solvent blend (B) comprises from 10% to 40% by weight of (i), the remainder of said solvent blend consisting of (ii).

13. A composition as claimed in claim 9 wherein said solvent blend (B) comprises from 60% to 85% by weight of (i), the remainder of said solvent blend consisting of (ii).

14. A composition as claimed in claims 8, 9 or 10 wherein said high viscosity poly(dimethylsiloxane) has a viscosity of from 60,000 to 500,000 centistokes at 25°C.

15. A composition as claimed in claims 8, 9 or 10 wherein said high viscosity poly(dimetylsiloxane) has a viscosity of from 60,000 to 500,000 centistokes at 25°C and said low viscosity poly(dimethylsiloxane) has a viscosity of from 10 to 100 centistokes at 25°C.

16. A composition as claimed in claims 8, 9 or 10 wherein said high viscosity poly(dimethylsiloxane) has a viscosity of from 60,000 to 100,000 centistokes at 25°C and said low viscosity poly(dimethylsiloxane) has a viscosity of from 10 to 100 centistokes at 25°C.