Note: Descriptions are shown in the official language in which they were submitted.
)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.
-- 5
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
-- 10 --
~)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.
-13 -
~-) * 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.
- 15 -
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.
- 17 -
Q931
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0
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.
- 20 -
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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.
- 22 -
- ~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.
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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.
.
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