Note: Descriptions are shown in the official language in which they were submitted.
11D83593
Thls lnvention relates to certaln novel silane
derivatlves which are useful as components of hydraulic flulds
and to hydraulic fluids containing such compounds.
Hydraulic 1uids based on glycol ethers have been
used in, for example, vehicle brake and clutch systems for
many years and still xemain the mo~t commonly used type of
fluid. However, specifications of required quality standards
laid down by hyaraulic systems manufacturers and non-commercial
organisations such as the Society o~ Automotive Engineers and
the U S Department of Transportation have become progressively
more severe. In particular, a need has arisen ~or fluias
having highe~ boiling points and, more importantly, higher
vapour lock temperatures both ~or the fluid as formulated
by the manufacturers and also for the fluid in the presence o~
water. Glycol ether based fluids are known to be deficient
in this respect due to the hygroscopicity of the fluid which
results in the absorption of water from the atmosphere.
This in turn reduces the boiling point and vapour lock
temperature of the fluid and with extended use the water
content of the fluid can build up to a level at which the
boiling point and vapour lock temperatures are reduced to a
dangerou~ extent. When subjected to heat, e.g. generated by
heavy braking, the fluid may boil or vaporise to a su~ficient
extent to cause a serious brake malfunction.
Hydraulic fluids having low hygroscopicity have been
developed, based on glycol esters, to deal with this problem.
Such fluids are relatively insensitve to the effect of
atmospheric moisture, but are more expensive than ~lycol
ether based fluids and have certain technical disadvantages,
e.g. their viscosity properties are inferior to those of
glycol ether based 1uids. Consequently, use of these low
hygroscopicity fluids has been mainly limlted to where the
2.
S93
:
desirable properties such as high boiling point and vapour
lock temperatures are deemed to outweigh their disadvantages.
Other types of water insensitive fluids have also been
developed. Nevertheless, manufacturers are still seeking
new fluids which combine as many as possible o~ the desirable
properties of both glycol ether based and low hygroscopicity
fluids and, desirably, have even higher boiling points and/or
vapour lock temperatures than the low hygroscopicity fluids.
Recently, there has emerged a growing tendency in
vehicle design to use a single hydraulic system to operate
equipment, such as power-steering, shock absorbers and brakes,
which hitherto were provided with separate hydraulic systems.
This has created serious problems in the formulation of
suitable fluids. The mineral oil based fluids hitherto used
in power-steering systems and shock absorbers are satisfactory
with respect to the nitrile and chloroprene rubber used for
the seals and gaskets in such systems but are highly detrimental
to the natural and styrene/butadiene rubbers used in the
constructian of hydraulic brake and clutch systems. This
~; 20 results in excessive swelling of the latter seals which can
lead to a serious malfunction of the brake or clutch system.
Conver~ely, the fluids hitherto used in brake and clutch systems,
which are normally based on glycols, glycol ethers and/or
glycol ether esters, and which have operated satisfactorily
in such systems, have a detrimenkal effect on the nitrile
and chloroprene rubber gaskets used in power-steering systems
and shock absorbers which can also lead to malfunctioning.
In the case of vehicle operation the characteristic of
reliability in operation, which i~ generally de~irable in all
mechanical devices, is increased in importance to an absolutely
essential re~uirement by virtue of safety considerations.
The need has therefore arisen for a fluid which can be used
.. .,. . , ~ : . . . .
.. . . . ..
-' ~Lo~3593
satisfactorily in a central system controlling the operation of a number of
different items of equipment.
We have now found certain novel silicon compounds which are useful -
as components of hydraulic fluids, for hydraulic brake and clutch systems
and also for central hydraulic systems. These compounds exhibit improved
rubber swell properties with respect to a variety of natural and synthetic
rubbers used in the construction of hydraulic systems and they are also
relatively water insensitive.
Accordingly, the present invention provides as novel ccmpounds,
; 10 silane derivatives having the general formula:
:. Rl ::
R4 - (oR5) - oR6 _ Si - R
OR
wherein:
(a) each Rl and R2 is independently aLkyl, alkenyl, aryl, alk æyl or
` aralkyl, a group of the formula -OR or a group of t~e formLla R -(OR )m~OR ~;
(b) R is a group of the form~la R ~(OR5)m - or a group of the
formula:
. R
I g
OR
and each R3 may be the same as or different from any other group R3;
(c) R4 is aLkyl, alkenyl, æyl, aLkaryl or æalkyl and each R4 may be
the same as or different from any other group R4;
(d) R5 is an alkylene group~and each R5 may be the same as or different
from any other group R ;
(e) R6 is an alkylene group and each R6 may be the same as or dlEferent
from any other group R ;
(f) m is zero or an integer and each m may be the same as or different
from any other m;
(g) each of R7 and R is independently alkyl, alkenyl, aryl, alk æyl
or aralkyl
-- 4 --
L~ , ,,
5g;~
a group of -the fonmula R4-(oR5) _oR6 or a group of the formwla -OR9 pro~ided
that only one of R7 and R8 may be a group of the formula -OR9, and
(h) R is a group of the formula R4-(oR5) - and each R9 may be the
same as or different from any other group R9;
provided that when Rl and R2 are ethoxy or methyl, and R3 is ethyl; R4-(oR5)m-
OR - is not a group of the formula C4HgO-C2H4-OC3~I6~ and when R and R are
ethoxy and R3 is ethyl, R4-toR5) -oR6- is not a group of the formula
C2H5-0-C H
In another aspect, of the present invention there is provided a
hydraulic fluid comprising from 0.5 to 99~ of at least one compound having
the general formNla:
Rl
R4-(oR5) - oR6 _ Si - R2 Ia
OR
,
wherein:
ta) each of Rl and R2 is independently alkyl, aIkenyl, aryl, alkaryl,
or araIkyl, a group of the formula -oR3 or a group of the formula R - toR5)m
- oR6 -;
(b) R is a group of the formula R - (OR )m ~ or a group of the
: formNla:
R
R8 _ Si - tOR )m~
OR
20 and each R3 may be the same as or different from any other group R3;
(c) R4 is aIkyl, aIkenyl, aryl, alkaryl or araIkyl and each R4 may be -
.; .
the same as or different from any other group R4;
(d) R5 is an alkylene growp and each R5 may be the same as or
different from any other ~oup R ;
- (e) R6 is an aIkylene group and each R6 may be the same as or
different from any other group R6;
(f) m is zero or an integer and each m may be the same as or different
- 5 - :
~3
L(18~S~;~
from any other m;
(g) each of R7 and R8 is independently alkyl, alkenyl, aryl, aIkaryl
or araLkyl, a group of the formula R4 - (oR5) - OR - or a group of the
formula -OR9 pro~ided that only one of R7 and R8 may be a group of the
; formula -OR ; and
(h) R9 is a group of the formula R - (oR5) - and each R9 m~y be
the same as or different from any other group R9.
Preferably, Rl and R2 are independently aIkyl containing from
1 to 18 carbon atoms (especially methyl) alkenyl containing from 1 to 18 ~-
carbon atcms, phenyl, alkyl substituted phenyl in which ~he alkyl substituent
contains from 1 to 12 carbon atoms, benzyl, a group of the formula -oR3,
or a group of the formula R4 - (OR5)m - oR6.
Preferably R4 iS aLkyl containing from 1 to 18 carbon atoms,
aLkenyl containing from 1 to 18 carbon atoms, phenyl, alkyl substit~d
phenyl in which the aIkyl substituent contains from 1 to 12 carbon atoms
or benzyl.
Preferably R iS an alkylene group containing from 1 to 15
` OE bon atoms, more preferably from 1 to 4 carbon atoms, and especially
ethylene or propylene.
Preferably R6 is an alkylene group containing from 1 to 15 carbon
atcms, and more preferably from 1 to 6 carbon atoms.
Preferably m is zero or an integer of from 1 to 4.
Preferably R7 and R8 areindependently aIkyl containing from 1 to
18 carbon atoms (especially methyl), alkenyl containing from 1 to 18 carbon
atoms, phenyl, alkyl substituted phenyl in which the alkyl substituent con-
tains from 1 to 12 carbon atoms, benzyl, a group of the formula R4 - (OR5)m
-oR6-, or a group of the formula -OR9 provided that only one of R7 and R8
may be a group of the formwla -OR9.
It is preferred that the silane derivatives of the invention con-
tain no more than 2 silicon atoms.
' ~:
- 5a -
~`''~
.
: . .
.
513~;~3
In the case of silane derivatives for use ln
hydraulic brake and clutch systems it is preferable for any
terminal alkyl groups present to be relatively short chain
alkyl groups, e.g. containlng from 1 to ~, more pre~erably
1 or 2, carbon atoms, in order to minimise the rubber swelling
effect on the seals and gaskets used in such systems. However
when used in a central system it may be more desirable to
effect a compromise between the requirements, often confllcting,
for each of the various seal and gasket materials. In this
case some, ox all, of the terminal alkyl groups may be longer
chain alkyl groups, e.g. up to 6, or even 8, carbon atoms.
Furthexmore, in the case of fluids based on mineral oil,
even longer chain terminal alkyl groups, e.g. containing
up to 16, or even 18, carbon atoms, may be necessary incrder
to effect oil solubility. The terminal alkyl groups may be
straight or branched chain but for oil solubility, particularly
in mineral oil, branched chain alkyl groups are preferred.
The silane derivatives of the present inventlon may
be readily prepared from appropriate haloalkyl silanes using
well-known techniques.
The silane derivatives of the invention may be
used ih hydraulic fluids as an additive, as a base stock or
as a component of a blend of base stocks. The proportions
employed may therefore vary over a very wide range e.g. from
0.5 to 99~ by weight based on the total weight of the hydraulic
~ fluid. When used as a base stock the silane derivatives
; will constitute the bulk of the hydraulic fluld, ~or example
from 75% or 80% to 99~ by weight, based on the total weight
of the hydraulic fluid. ~he remainder of the hydraulic fluid
may be composed of conventional hydraulic fluld additives
and/or small quantities of ot~ hydraulic fluid base-stocks.
When used as a component of a blend of base stocks
~.~f33S9;~
the total blend of base stocks wlll llkewise constitute the
bulk of the hydraulic fluld. In this case, the base stocks
may be predominantly one or more silane derivatives blended
with a lesser quantity of one or more other base stocks so
as to modify the properties of the silane derivatives. Thus,
the hydraulic fluid may contain, for example 55% to 75% by
weight of one or more silane derivatives based on the total
weight of the hydraulic fluid. Alternatively, one or more
other base stocks may be modified by blending with a lesser
quantity of silane derivatives so that the hydraulic fluid
contains, e.g. from 20% to 40% by weight silane derivative.
In addition, a compromise between the properties of the silane
derivatives and the other fluids may be effected by blending
in approximately equal quantities to provide fluids containing
from 40% to 55% silané derivative.
When used to suppress the sensitivity of hydraulic
fluids, and in particular the boiling point and vapour lock
temperatures of the fluids, to water the silane derivatives
; are preferably used in amounts in the range of 20% to 55%,
more preferably 20% to 40%. Alternatively but less preferably,
an improvement can also be obtained using lower amounts of the
silane ~erivatives, e.g. from 0.5% to 15% or 20% by weight
based on the total weight of the hydraulic fluids. The bulk
of such fluids will be constituted by one or more base stocks
such as hereinafter described.
When the silane derivatives are used as a component
` of a blend of base stocks the resulting hydraulic fluids may
-~ contain conventional hydraulic fluid additives in llke manner
as when the base stock substantially consists o~ the silane
derivatives. Similarly, when used as an additive the silane
derivatives may, i~ desired, be used in conjunction with
conventional hydraulic fluid additives.
.
.
.... .;
35~33
Co~ventional additives are normally employed in
small amounts such as 0.05% to 10%, for example, 0.1 to 2%
by welght.
Base stocks with which the silane derivatives may
s be blended, or with which they may be used as additives,
include mineral oil, polyoxyalkylene ylycols and ethers thereof,
alkyl and polyoxyalkylene glycol ether esters o~ mono-, di
or poly carboxylic acids or boric aci~, formals, acetals,
phosphate esters, silicones, monocarboxylic acid esters of
di- or polyalcohols and similar fluids well known in the art.
In a particular aspect of the invention there is
provided a hydraulic fluid consisting essentially of a com-
bination of from 5 to 30~ by weight of at least one silane
derivative of Formula I as hereinbefore defined and from 5
to 30% by weight of at least one compound having the general
formula:-
OR12 Rll ORlZ oR12
_ Si - OR12or Rll _ Si - 0R12 or Rll _ Si - 0 - Si -
oR12 oR12 l13 R13
; 20 II III IV
- wherein Rll is alkyl, preferably containing from l to 18 carbon
atoms, or~aryl, preferably phenyl; Rl2 is alkyl, preferably
containing from l to 18 carbon atoms, aryl, preferably phenyl,
alkaryl, preferably alkyl substituted phenyl in which the
alkyl substituent contains from 1 to 12 carbon atoms, or
aralkyl, preferably benzyl, or a group of the formula
R4-(oR5)m-; R13 is alkyl, preferably containing from 1 to 18
carbon atoms, aryl, preferably phenyl, alkaryl, preferably
alkyl substituted phenyl in which the alkyl substituent
contains from l to 12 carbon atoms, or aralkyl, preferably
benzyl, or a group of the formula R4-(oRS)m-o-; and R4, R5
and m are as hereinbefore defined, in a glycol ether base stock.
: .... ~ ,. .
lU513S93
In a further particular aspect o~ the invention
there is provided a hydraulic fluid consisting essentially of
from 10 to 90% by weight of at least one silane derivative
of Formula I as hereinbefore defined and from 90 to 10%
by weight of at least one compound of Formula II, III or IV
as hereinbefore defined.
Regardless o~ precise composition it is highly
desirable that the hydraulic fluids of the present lnvention
have a kinematic viscosity at -40C of not more than 5,000 cSt,
especially not more than 2,000 cSt. It is also desirable that
the hydraulic fluids have a boiling point of at least 260C.
In a further aspect of the present invention there
is provided a hydraulic system for transmitting power by
hydraulic means which system contains as the functional
fluid, a hydraulic fluid as hereinbefore described.
In yet another aspec~ of the present invention
there is provided a method of operating a hydraulic system
which comprises introducing into the hydraulic system a
hydraulic fluid as hereinbefore described and transmitting
power by applying pressure to the hydraulic fluid.
The present invention will now be illustrated with
refere~ce to the following Exam~les:-
Example 1
Tris(methoxy)-3-chloropropyl silane (794 g; 4 moles)
and methyl ~-riglycol (2296g; 14 moles) were heated under
nitrogen cover in a glass flask fitted with a 1 ft packed
column until 188.1 g of MeOH had been removed from the mixture.
The column was removed and heatin~ continued at a bottom
temperature of 200C until 317.4 g (calc. 384) had been obtained.
Sodium (101.2 g; 4.4 g atom) was dis~olved in
methyl triglycol (1000 g, 6.1 mole) and the resultant slurry
added to the reaction mixture which was maintained a-t 100C
9.
~J83593
for 3 hours. The product was ~lltered, stripped under 0.1
mm Hg at a bottom temperature of 180C, and reflltered.
2660 g (92%) of a dark liquld was obtained con-
talnlng 4.20% Si~ (calc. 3.88% Si for tris (methyltriglycol)-
3-methyltriglycolpropyl silane). The product had a boiling
point of 320C and a vi~cosity at -40C of 2306 cS. Good
'~ results were obtained with rubber swell tests on SBR G9
; (4~2%) and Natural R32 (-1.0%).
Example 2
Tris (methyldiglycol)-3-methyldiglycolpropyl silane
was prepared in similar manner from tris(methoxy)-3-chloro-
propyl sllane (198.5 g; 1 mole), methyl diglycol (396 g;
3.3 mole) and sodium (25 g; 1.1 g atom) in methyl diglycol
(400 g; 3.4 mole).
77 g (calc. 96 g) of MeOH was collected in the
first stage. 409 g (75%) of product was obtained containing
6.092% Si (calc. 5.12) and 0.2% chlorine. The product had a
viscosity at -40C of 1051 cS, a boiling point of 310C. and
; gave good results,in rubber swell tests: SBR G9 8.9~ and
Natural R32 2.0~.
Example 3
Tris (tridecanoxy)-4-trid~canoxypropyl silane was
prepaxed in similar manner from 3-chloropropyl-trimethoxy
silane (397 g; 2 mole)and tridecanol (1400 g; 7 mole) and
p-toluene sulphonic acid (0.2 g) and sodium (50.6 g;
2.2 g atom) in tridecanol (800 ml, 4 mole). 168 g (calc.
192) methanol was obtained. 711 g (82%) of product was obtained
containing 3.46% Si (calc. 3.23).
A blend of this product (50%) in a DTD 585 mineral
30 oil (50~) had a -40C viscos:lty of 2313 cS. The vapour lock
- temperature after heating with 0.5~ H20 at 100C for 72 hours
was 225C.
,~ 10.
` 1()~35~3
Exampl e ~ 4 to 2 6
Hydraullc flulds ln accordance with the invention
were subjected to one or more o~ the following tests:-
(a~ Kinematic viscoslties at -40C, in centistokes
(CS), were measured ln the manner set forth ln the
SAE J 1703c specification.
(b) Rubber swell properties were evaluated for
s~yrene/butadiene (SBR), nitrile and ethylene/propylene
rubbers. In the case of SBR, the test was carried
out using standard SAE SBR cups in the manner set forth
in the FMVSS 116 DOT 3/4 specification. Rubber swell
properties with respect to nitrile rubber were
determined by measuring the increase in volume of a
2.54 cm square, 2 mm thick nitrile rubber specimen in
50 mls of test fluid at 120C for 70 hours. The test
with respect to ethylene/propylene rubber was carried
out in the same manner as for nitrile rubber but using
ethylene/propylene rubber ring seals (as used in the
aviation industry~.
(c) Vapour lock temperatures were determined after
prior subjection of the fluids to a Humidity Test
s~bstantially as described in the FMVSS 116 specification,
but without a reference fluid. In the case of fluids
comprising a glycol ether base stock, the vapour lock
temperatures were determined by the Markey Vapour Lock
Test carried out in the apparatus and in the manner as
laid down in the SAE J 1705 specification for sillcone
brake fluids. Vapour lock temperature~ for non-
glycol ether based fluids were determined by the Gilpin
Vapour Lock Test as specified ln SAE Paper 710 253
entitled "Operatlng Performance of motor vehlcle
..
11 .
.. . .
' . ,
`` 9 ~835~3
brakin~ systems as affected by fluid w~ter con-tent",
the Gilpin vapour-lock temperature being taken to be
the temperature corresponding with the appearance of
3 ml of bubbles.
(d) Hydrolyticstabilities were determined by
heating the test fluid + 10% water in a sealed ampoule
for 24 hours at 100C and thereafter, on cooling,
noting any gelling or separation. (Silanes of
Formulae II-IV alone or in admixture with glycol ether
base stocks normally gel under these conditions.)
Details of the fluids tested and of the results
obtained are given in Tables 1-3.
The abbreviations and commercial products referred
to in Tables 1-3 are as follows:-
Butyl Monoglycol - Ethylene glycol mono
butyl ether
D P M - Dipropylene glycol mono
methyl ether
M T G - Triethylene glycol mono
methyl ether
M D G - Diethylene glycol mono
methyl ether
Mineral Oil A _ Naphthenic mineral oil
having a viscosity of
~ 130 cS @ -40F., 3.5 cS
@ 100F., and 1.31 cS
@ 210~F.j pour point
-700F., Boiling point
248 C. Flash point 208~C.
aniline pt. 76~C.
Mineral Oil D ~ Ditridecyl dodecanedioate
Refrigerant Oil B - Commercially available
- refrigerant oil manufactured
; by Briti~h Petroleum
under the trade mark
ZERICE S 53 and believed
to be a mixture of
alkylated benzenes.
12.
`: ~O~ig3
,..~
Ra~rigerant Oil C - ~ blend o naphthenic
-: mlneral oils:relakive
density 0.920, Viscosity
at 100uF. 63.0 cS,
Viscosity at 210VF.
6.1 cS, Open Flash point
183~C., pour point -36~C.
Silicone Fluid - Commercially available
silicone brake fluid
supplied by Dow Corning
under the designation
02-1062.
: E 555 - Commercially available
ethylene/propylene glycol
ether supplied by Dow
Chemical Company having
:- a molecul~r weight of
about 243 and wherein
the terminal ether alkyl
. groups are believed to
: be predominantly methyl
but with a proportion
being ethyl.
A 79 Nitrile Rubber - Commercially available
nitrile rubber - as
~LJ used in Girling~brake
systems.
r~ ema~-~
.
: ` '
, ~
~ '
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: 13.
i~ .. . ~ . .. ....
~33~ 3
:~
¦ ~ ~ I ~ IN ~ IN D la~ ¦ O IN
~ _ _
~ ~ ~ oo a~ ~ 03 ~ ~o ~ _~
m ~ o ~ o ~ ~ o ~ u~ ~ ~ a:
H ~ ~ ~ ~ H ~;;
r~ h 0 ~ ~ ~ . ~1 .~
u h h ô ~ ô ~ o o o
R ~ f ~
rn ~ ~ ~ ~ r~ ~3 ~ r~ ~ .
. M F~ r~ ~ ~ r-~ rh c-~ r~ r~l
~ ~ ~ ,.~ ~, ~ a) o~ () , ~
~- ~ - - -
10~$g3
~ Q~ r~
o~ ~ t ~o
s~ ~ ~ o ~ .~ .
. _ ,
Xa
~'~ ~ O O N d- CO ~~ 1--l i ~
,~ O HI--I ~J1--I ~ ~1 CO ~ ~ _
H _ _ . _ .
~ H . .
~1 ~ ~ ~ ~10~
r ~ R
., ._ __ , a
R a ~ R ~ ~ ~ L i ~
~ ~ I .1 0 -- o ,, hH ~ tl ~1 .1 N ~ O
~ _ ___ ~ __ ___ (~D~
~3 ~LI r; r~ r-l rl r -I r I N N E-i
,: , '
593
TAB~. S
~ .
EXAMP~E TI~ST FLUID ~YDRO~YTIC S'rABI~ITY
N0
-- . .~ . I ~__ ,
22 ~i3 (E555~-dimethyl silane - 10 Clear, mobile,
(MDG)(3-MDG propyl)silane no sediment
. ..... , .......... . ~ .
23 Tris 5DPM)-methyl silane - 40~ Mobile - not star
Tris (DP~X3-DPM propyl)silane bright, some deposit
- 60% believed due to
irnpurity of products,
: otherwise s~t~sfactory
24 ~''Tri~ ~DPM)-me'~hyl silane - 10% No separation, slightl~
Tris (2-ethylhexanoxy)-3-(2- cloudy, no gelling
: ethylhexanoxy) propyl
silane - 90%
- 25--- Bis ~E555)-dimethyl silane - ?~ ~ Satisfactory
Tris (MDG)(3 MDG propyl~silane
: Triethyleneglycolmonoethylether
- 60%
26 Bis (E555)-dimethyl silane - 20 ~ Satisfactory ~
: . Tris (MDG)(3-MDG propyl)silane
~ Triethylene glycol monoethyl
: ether - 60%
I_
.':
15.
:`
. ' ,
- , , , , -,
.. . .
