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Патент USA US3062758

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United States Patent 0
3,062,747
be"
1C6
Patented Nov. 6, 1%52
2
gas
been obtained. However, the viscosity of the hydraulic
3,tlti2,747
brake ?uids prepared at least in part from these high
HYBRAULEC BltAKE FLUIDS;
molecular weight organic liquids, other factors being
Harvey R. Fife, deceased, late of Chapel Hill, N.C., by
constant, generally increases in direct relationship to the
Geraldine H. Fit'e, exccutrix, Chapel Hill, N.C., and
Richard W. Shi?er, Briarcliit" Manor, N.Y., assignors to 5 molecular weight of the aforementioned liquid com
ponent. Consequently, although a suitably high boiling
Union Carbide Qorporation, a corporation or‘ New
point may be reached, subsequent use of the hydraulic
York
brake ?uids is often precluded due to their high viscosity,
No Drawing. Filed June 23, 1960, Ser. No. 38,397
particularly at low temperatures. On the other hand,
4 Ciainis. (Cl. 252-73)
when conventional diluents, such as diethylene glycol
The present invention relates to ?uid compositions for
monoethyl ether, ethylene glycol monobutyl ether, meth
use in hydraulic brake systems, and in particular, is
ylamyl alcohol or the like, are also incorporated as addi
concerned with improved, high-boiling hydraulic brake
?uids consisting essentially of certain low molecular
tional components in the hydraulic brake fluids in an
amount sufficient to decrease the viscosity of the ?uids
weight polyoxyalkylene gylcol monoalkyl ethers.
to a commercially acceptable level, the boiling point of
Hydraulic brake ?uids have been in common use for
some time. Moreover, over recent years, the develop
the resulting ?uids frequently is decreased to an undesir
able extent. As a result of these and other considera—
tions, numerous di?iculties have heretofore been en-_
ment of improved ?uid compositions of this nature has
received
art. Forconsiderable
instance, with
attention
the increasing
from thoseweight,
skilled horse
in
power and speed of modern automotive vehicles, a com~
mensurate increase in the temperature developed during
countered in formulating complex ?uid mixtures for use
the normal operation of automotive hydraulic brake
systems has been brought about. Consequently, the heat
through the practice of the present invention, whereby
build-up within these brake systems, hence within the
hydraulic ?uids contained therein, has also increased con
siderably over that encountered in the past. Unfortu
nately, under these more severe operating conditions,
positions for use in hydraulic brake systems having a
as hydraulic brake ?uids.
_
V
The disadvantages of the prior art, as hereinabove
described, can now be overcome to a substantial extent
one or more of the following objects can be achieved.
It is an object of this invention to provide ?uid com
minimum boiling point of about 400° F., yet retaining
substantially all of the characteristics hereinabove de
scribed which are presently desiredin hydraulic brake
substantially below about 400° F. often demonstrate a
?uids. It is another object or" this invention to provide
tendency to vaporize in use. Thus, under such con~ 30 improved hydraulic brake ?uids comprised essentially of
ditions, the normally liquid and non-compressible hy
a single ?uid component, such essentially sole ?uid com
draulic brake ?uid is converted into a compressible
ponent in and of itself performing the functions of a
vapor, thereby rendering the hydraulic brake system in
hydraulic brake ?uid, although it can be'rnodi?ed for
conventional hydraulic brake ?uids having boiling points
operable.
ln an effort to overcome this disadvantage,
various other purposes.
higher-boiling hydraulic brake ?uids evidencing less of
a tendency to vaporize during use are constantly sought
by the art.
However, it is also important that the desired higher
boiling points be obtained with little or no sacri?ce of
other essential properties of the hydraulic brake ?uids.
By way of illustration, :1 ?uid composition of this type
must be stable both chemically and physically The
component parts of the fluid must not react with one
another under the various operating conditions of tem
perature and pressure and must not separate out at low
temperatures. In addition, the ?uid should be sub
stantially non-reactive toward other material components
of the hydraulic brake system, such as the metal or
rubber parts of the system which are exposed to the
?uid during normal operation.
in general, no one ?uid composition has, to date, been
found entirely satisfactory as a high~boiling hydraulic
brake ?uid. Rather, complex mixtures of various ?uid
compositions are ordinarily employed, each component
contributing certain desirable properties to the hydraulic
brake ?uid of which it is a part. Unfortunately, certain
di?iculties ordinarily accompany the formulation of such
?uid mixtures. For instance, the proportions of the
various ?uid components must be carefullyv chosen and
Still other objects will become '
apparent in connection with the following description.
The present invention is based upon the ?nding that‘
certain low molecular weight polyoxyalkylene glycol
monoalkyl ethers will serve as e?icient hydraulic brake
40
?uids. More particularly, in the broadest aspect, the
hydraulic brake ?uids of this invention are the normally
liquid methyl and ethyl monoethers of mixed po1y(oxy
ethylene-oxy-1,2-propylene) glycols (at) having an aver-'
age molecular weight of from about 175 to about 325;
(b) in which there are present an average of from about
3 to about 5 oxyalkylene groups per molecule; (c) in
which the oxyethylene and oxypropylene groups present
each represent from about 35 percent to about 65 percent
by weight based upon the total weight of the oxyalkylene
50 groups present; and (d) in which the terminal alkyl
radical is selected from the group consisting of the methyl
and ethyl radicals. These liquid compositions possess
boiling points of at least about 400° F., have desirable
freezing point and lubricating properties and no not have
an excessive swelling effect upon rubber. Accordingly,
it has been found that the polyoxyalkylene glycol mono
alkyl ethers of this invention do not require modi?cation
with other dissimilar ?uids in order to provide composi
tions suitable for use in hydraulic brake systems. and can
therefore be employed as an essentially single ?uid com
controlled within limited ranges, since an excess of any 60 ponent, high-boiling hydraulic brake ?uid.
one component is also likely to impart certain undesir
When desired, small amounts of conventional corro
sion inhibitors and antioxidants can be added to the hy
draulic brake ?uids of this invention. Moreover, with
mixtures containing three or more different ?uid com
those additives evidencing limited or non-solubility in the
65
ponents.
7
able properties to the hydraulic fluid. This problem be
comes particularly predominant with the more complex
As illustrative in this connection, high molecular weight
organic liquids, such as the polyoxyalkylene glycol
ethers having an average molecular weight of about 500
or higher, and particularly the butyl ether derivatives,
polyoxyalkylene glycol monoalkyl ethers herein described,
a small amount of a lower alkylene glycol generally just
su?icient to provide a solvent for the additive can also be
incorporated in the hydraulic brake ?uids of this inven
have heretofore been employed as a major or substantial 70 tion without disadyantageously affecting the desirable
component of hydraulic brake ?uids.
In this manner,
hydraulic brake ?uids possessing high boiling points have
physical properties of the fluid. It is to be noted in this
connection, that the lower alkylene glycol need not be
spaagmv
3
:5.
utilized in the absence of ‘H1056 corrosion inhibitors or
example, by conventional processes of the type described
in UZS.’ Patent 2,425,755, involving the ‘addition of both
antioxidants evidencing limited or non-solubility in the
polyoxyalkylene glycol monoalkyl ethers of this inven
ethylene oxide and 1,2-propylene oxide, either sequentially
tion, and need never be employed in amounts ‘su?icient to
or as a mixture, to a monohydroxy alcohol such as meth
substantially modify ‘the essential“ physical ‘properties'jot ‘
such "polyoxyalkylene glycol‘ monoalkyl ethers ‘Whichfren-j,
der'jthe compositions suitable for‘ use as‘hydraulicfbrake
?uids‘.
',
‘l
",i:
.
e
i
anol, ethanol, ethylene glycol monomethyl ether, ethyl
ene glycol monoethyl ether, propylene glycol monomethyl
etherv or propylene-glycol monoethyl‘ether. These'rproc“
it
esises are ordinarily carried out in the presence of ‘catalytic
"The useful range‘of the'polyoxyalkyleiie glycol'mon'oi':
amounts‘of'an alkaline catalyst, such‘ as‘sodium hydroxide
brake ?uids‘in accordance with‘ this inventitin has'heeni
found to‘ be‘limited in part‘by their molecular weight.
a reaction‘ temperature of_ fromlabout 80° C. ‘to about
alkyl ethers to be employed as high-‘boiling hydraulic.
or potassium‘hydroxide, u'nder moderate pressure and at
160° C. Somewhat. higher ,or lower reaction tempera
For example, ‘the polyoxyalkylene' glycol monoalliyl'ethers
tures can also be employed satisfactorily.
having an average molecular weight of below about 175,.
containing an average‘ of less‘ than about’3'oxyalkylene
In the‘ production of the polyoxyalkylene glycol mono
groups per‘molecule,‘ordinarily‘do not possess the lubri-_
eating‘ properties desiredjofjthe hydraulic brake'l?uid.
Moreover, such ‘compounds may have boiling points ‘below
about 400° F., ‘thusf precluding their sole use'inE applicaé;
15 alkyl .ethersr as ‘herein described, the reactants are‘gem‘
era‘l'ly utilized in proportions elfecting the presence in the
reaction mixture of ‘from about3>to about 5 toxyalkylenej
7 groups per mole of monohydroxy alcohol undergoing re
action. ‘Thus, for example,‘ when the monohydroxy alcohol
tionsfrequirin'g a high-boiling hydraulic b'rake’iiuid. ' On
is an alkylene glycol monoether derivative in which one
ethers having ‘an average ‘molecular weightfabo‘ve about
325', containing ‘an'avera'ge‘of substantially more ‘than
about>4 moles of alkylene oxide per mole of the‘mono
hydroxy alcohol should be employed in the reaction. In ‘
the ‘other, ‘hand, the polyoxyalkylene, glycol gmolno'alkyli
oxyalkylene group is initially present, not‘more than
about 5 oxyalkylene groups per molecule, have viscosities
that’are‘ ‘too high, particularly at ‘low, temperature, to 1
this manner, an average substantially in excess of about
5 oxyalkylene groups per molecule will not be present
in the product. In "addition, the speci?c‘ reactants and
their proportions'must be chosen so that‘ the resulting
product will contain not less than about 35 percent nor
permit‘ theiruseas single ?uid component high-boiling
hydraulic brake'?uids. Many such highrnolecular weight
liquids also have undesirable freezing point properties.‘
:‘Thepolyoxyalkylene ‘ glycol monoalkyl ethers suitable
more than about 65 percent‘by weight of either oxyalkyl- ‘
for use as high-boiling hydraulic‘ brake ?uids, in, accord— , 30 ene group, i.e.' oxyethylene or oxypr‘opylene group, based
ance‘with, this invention have further beenfound limited,
byhthe‘number ofcarbon atoms'in the alkyl radicalsof
upon the'total weight of the oxyalkylene groups present,
and preferably so that the resulting product will contain
th'e'jalkyl ether grouping containedtherein. , For instance,
as the‘ number of carbonatoms in theaforementioned alkyl
_ from about 50'percent to about 60 percent by weight of
radicals increases, a concomitant increase has ,beenufound.
oxyalkylene ‘groups present. Thus, for example,‘when
themonohydroxy alcohol is an‘ alkylene glycol monoethcr
oxyethylene groups based upon the total weight of the
to occur, in theswelling effect that‘these ?uidshave upon ,
rubberjHence, since‘ in commercial use, an excessive‘
swelling“ etfectjupon rubber ‘is a characteristic to be
avoide‘d, ,the useful polyoxyalkylene, glycol monoalkyl.
others are, in‘ accordance with this invention, limitedv to 40
those in whichthealkyl grouping contains up to about .
2 carbon: atoms,‘ such as methylor ethylqradicals, and
is‘preferably a methyl radical.
.Moreover, it has been found. that‘ an, increase in ‘the
oxide'c'orresponding to the oxyalkylene' group present in
the monohydroxy alcohol, depending upon the proportion
in which the reactants are employed. By way of illustra
tion,fpa'rticularly useful ‘products have been obtained by ‘
reacting either methanol or ethylene glycol monomethyl
ether with an equal weight mixture ofeethylene oxide and
1,2-propylene oxide in aeproportion of from about 3, to
oxypropyleneeontent of the polyoxyalkylene glycol mono»
alkyl ethers also engenders a commensurately. increasing,
swelling e?'ect upon rubber. Thus,,for_ reasons similar to,
those; just , described, the, polyoxyalkylene ; glycol .mono
about 4 moles of the alkylene oxide mixture per mole of
the monohydroxy alcohol, undergoing reaction. It is to
alkyl ethers of this invention are limited to those in which
the. oxypropylene groups present represent a. maximum
be" noted in, this‘connectio'n, that, as employed herein,
of‘ about 65 percent by weight‘based upon the total weight,
of theoxyalkylene groups present; ,Onthe. otherrhand,
while a low, oxypropylen‘e content is desirablein order to
minimize rubberswelling, a correspondingincreasc' in the
oxyethylene content of the polyoxyalkylene'glycol- mon‘o-
derivative, the’al'kylene oxide mixture'utilized ‘as a re
actant should not be ‘composed of more than from about
‘ SOpcrcent’toabout 60 percent by weight of the alkylene
.
1 ..
:
‘
alkyl, ethers, has been found to have adverse-effect upon‘,
the desired,low,temperature properties: of the product;
and‘ particularlyupon the freezing point of .theEproduct;
This is espeeiallyrtruetin connection with :the relatively“
higher molecular Weight p'olyoxyalkylenel glycolr'mo‘noé
alkyl ,ethers containing an averag'e'of about’S oxyalkylene ?
having higher ,viscosities. Concordant‘ 'with these=?nd—
lar weight of the mixture.
,
‘
,
.
‘Upon completion of the reaction producing the poly‘
oxyalkylene glycol monoalkyltethen'the desired product
is“ generally recoveredtrom the crude reaction mass as a
residue ‘product by neutralizing the alkaline catalyst by
reaction,‘ with an acid with which the catalyst .will form
, a ?lter‘able salt, orvby contacting the catalyst with a suit
able adsorbent, ‘followed by the ?ltration and distillation
60
groups‘ per. molecule. , In addition,‘ an increase ‘ 3in the"
oxyethylene content hZtSl?lSO been found ‘to provide ?uids.
the number of moles oflthe'alkylene oxide mixture utilized
as a magenta calculated based upon, the average molecu
.,
oi the crude. The ?ltration can be performed, either prior
or subsequent to, distillation“, Moreover, under certain
circumstances as hereinafter described, the?ltration step
can be' omitted.
The distillationiof the crude is conducted in order to_
ings,»the' polyoxyalkylene . glycol monoalkyl‘ ethers ‘of this
remove as a distillate anyunreacted alkylene oxide and/or
inventionare, for commercial purposes, ‘restricted’ to‘those‘ '
unreacted' monohydroxy alcohol, as well as any water
in‘ which the, oxyethylene group's presentfrepresent a maxi:
imum ‘of about 65 percentlby weight based upon- the total? ;
weight of the oxyalkylene groups present. The preferred,
polyoxyalkylene, glycol monoethers'are those in which. the__ 70
oxyethylene, groups presentrcpresent from about 50111611‘
centto about 607 percent by weightbase d
weightuofithe oxyalkylene groups present.
upon the
,Thefpolyoxyalkylene glycol monoalkyl'ethers
and monoalkylene: glycolpresent, and to-assure the
recovery of‘desired polyoxyalkylene glycol monalkyl ether
as ‘the residue product.v To. this end, the ‘crude is‘ prefer
ablystripped up to a temperature of about 65° C. under a
reduced pressure o‘fabout 5 millimeters of mercury. Any
total,
other convenient recovery procedure can also be utilized.
When thepolyoxyalkylene glycol monoalkylrethers of
.75 this invention are tojbe used as hydraulic brake ?uids,
iuvention can be‘ prepared in any convenient manner, as ‘for,
small amounts otconventional corrosion inhibitorsand:
spears?
connection with‘ the following speci?c. examples, but is
antioxidants can, when desired, be added thereto. Gen
not intended to be limited thereby.
EXAMPLE I
erally, for this purpose, a total of from about 0.2 percent
to about 2 percent by weight of the additive(s), based
upon the total weight of the hydraulic brake ?uids is
utilized, although somewhat higher'or lower concentra
F
boiling hydraulic brake ?uid was prepared by the reaction
of an equal weight mixture of ethylene oxide and 1,2
corrosion inhibitors include amines such as mono- and
dibutyl amine, mono- and diamyl amine, dioctyl amine,
etc.; salts of these amines with acids such as boric acid
or dilinoleic acid etc.; alkali metal borates such as borax
or potassium. tetraborate etc.; and the like. Such com~
pounds, it is to be noted, ordinarily serve as bu?ering
agents by providing reserve alkalinity, so that the pH of
the resulting ?uid composition is maintained within a
commercially acceptable range. Suitable antioxidants in
A liquid poly(oxyethylene-oxy-1,2-propylene) glycol
monomethyl ether composition suitable for use as a high
tions are also effective. By way of illustration, suitable
propylene oxide with ethylene glycol monomethyl ether
in a proportion of 3.0 moles of the alkylene oxide mix
ture per mole of the monohydroxy alcohol. The re
action was carried out by introducing the alkylene oxide
mixture to the monohydroxy alcohol in the presence of
about 0.2 percent by weight of a potassium hydroxide
J catalyst based upon the total weight of the reactants,
at a temperature of about 110° C., under a pressure of
clude diphenylo‘l propane, phenyl alpha-naphthyi amine,
about 60 pounds per square inch and at an alkylene oxide
feed rate of about 100 cubic centimeters per minute.
polymerized trirnethyl dihydroxy quinoline, alkyl phenols,
polyalkyl polyphenols, styrenated phenols etc., and the
like. In particular, especially good results have been
Upon the complete introduction of the alkylene oxide
realized by adding mixtures of borax, or other alkali 20 mixture, the reaction mixture was stirred at 110° C.
for an additional period of about one hour. There
metal borates, and diphenylol propane to the polyoxy
after, the crude reaction product was distilled in the
alkylene glycol monoalkyl ethers of this invention in con
presence of 2 percent by weight of an aluminum silicate
centrations of from about 0.2 percent to about 0.5 percent
adsorbent (Filtrol X-202, manufactured by the Filtrol
by weight of each of the additives based upon the total
Corp), at a temperature of 65° C., under a reduced
weight of the hydraulic brake ?uid.
pressure of 5 millimeters of mercury. The residual prod
The corrosion inhibitors and antioxidants can be in
corporated in the polyoxyalkylene glycol monoalkyl ethers
uct subsequently ?ltered to remove the absorbent.
To
borax or boric acid is particularly useful in the neutraliza- .
diphenylol propane, 2.5 percent by weight of ethylene
glycol and 2.5 percent by weight of diethylene glycol
the poly(oxyethylene-oxy-1,2-propylene) glycol residue
of this invention either prior or subsequent to the dis
product thus obtained, there were added 0.5 percent by
tillation of the crude as hereinabove described. In this
connection, it has been found that a compound such a 30 weight of potassium tetraborate, 0.5 percent by weight of
tion or removal of the alkaline catalyst. Thus, for in
stance, borax or boric acid can be added to the crude in
an amount su?icient to react completely with the alkaline
catalyst. The resulting alkali metal broate product there
based upon the total weight of the resulting ?uid. The
product was then evaluated as a hydraulic brake ?uid
05 U~ by a comparison of the physical properties of the product
with speci?cations adapted by the Society of Automotive
by formed need not be ?ltered from the crude since such
Engineers for hydraulic brake ?uids as described in SAE
speci?cations 70R 1 and 70R 3. The results obtained
compound serves as a corrosion inhibitor when present.
In addition, when the incorporation of a corrosion in
are set forth below in Table A.
hibitor or antioxidant which evidences limited or non
solubility in the polyoxyalkylene glycol monoalkyl ethers
40
of this invention is desired, e.g. an alkali metal borate, a
Table A
small amount of a lower alkylene glycol in which such
additive is soluble, and which in turn is soluble in, or
Product
miscible with the polyoxyalkylene glycol monoalkyl ether,
can also be incorporated therewith.
Properties
SAE Speci?cations
The term “lower
alkylene glycol,” as employed herein and in the appended
claims, is meant to include ethylene glycol, propylene
glycol and mixtures thereof with diethylene glycol and/ or
dipropylene glycol in which the monomeric glycol com
Viscosity (centistokes) 1.
ponent is present in substantial, and preferably at least 50
Rubber Swelling (percent)
Evaporation Test (percent residue).-__
4.0 (ma-imum).
20 (minimum).
Cylinder Residue Test 4 _____________ ._
passes.-.“ No hard, dry or
375 (minimum).
180 (minimum).
4.0 (minimum).
Boiling Point (° F.) _________________ __
Flash point- (° F.) _____ ._
'
1,800 (maximum).
Viscosity (ccntistokes) 2. _
equal proportions with respect to the dialkylene glycol
component. Particularly good results have been obtained
using mixtures of ethylene glycol and diethylene glycol
or corrosion.
Lubrication, Heat Stroke Test ______ __ passes“-.. 150.00 strokes at
in which each component is present in equal concentra
Cold Test 5 __________________________ __
tion by weight. The lower alkylene glycol is generally
gummy residues
158° F. and 500
psi.
and preferably employed in an amount just suf?cient
pH (before) 6 ________________________ __
pH (after) 6 _________________________ __
Corrosion Test (mg/cm!4 loss): ‘I
oxidant which otherwise evidences insolubility or only
partial solubility in the polyoxyalkylene glycol mono
alkyl ethers of this invention and, to this end, is utilized 60
greater than about 5 percent by weight based upon the
total weight of the hydraulic brake ?uid. Moreover,
the lower alkylene glycol can be incorporated in the
polyoxyalkylene glycol monoalkyl ether product either
prior or subsequent to the distillation of the crude as here—
inabove described, with the latter procedure ordinarily
being preferable due to the otherwise possible loss of the
lower alkylene glycol during distillation. Where borax
or boric acid is employed to react with the alkaline cata
lyst, however, the lower alkylene glycol is nevertheless
generally introduced prior to the distillation of the crude
in order to keep the resulting borate product in solution.
The present invention can be illustrated further in 75
Flow in 5 sec.
pours
to provide a solvent for the corrosion inhibitor or anti
in a maximum concentration of up to about 10 percent
by weight, and more preferably in a concentration no
clear and
Cast iron ________________________ ..
l0.85-.__-_ 7-11.
10 65-..... 6-11.
9.60?
1 Measured at 130° F.
2 Measured at —40) F.
48 Measured using
after 14
Manhattan
days at 158°
Natural
F.
rubber, after 6 days at 210°
5 Measured after 6 days at —40° F. and after 6 hours at —“0° F.
6 Measured from a 50 percent aqueous mixture.
1 Measured after 5 days at 210° F.
From the above table, it can be seen that the hydraulic
brake ?uid of this invention meets the existing. SAE
speci?cations shown and, advantageously, and has a boil
ing point well in excess of 400° F.
EXAMPLE II
Various liquid poly(oxyethylene-oxy - 1,2 - propylene)
_
.
7
8
glycol monomethyl ether compositions suitable for use as
high-boiling brake ?uids were prepared by the reaction of
scribed in Example I. The results obtained are tabu
lated below in Table (3.
equal weight mixtures of ethylene oxide and 1,2-propylene
Table C
oxide with methanol and with ethylene glycol mono
methyl ether. In run Nos. 1 to 4, ethylene glycol mono- 5
Run NOS
methyl ether was employed as a reactant; in run Nos. 5
to 7, methanol was employed as a reactant. Further, in
'
3
6
run No. 1, the reactants were utilized in a ratio of 2.9
moles of the alkyleneoxide mixture per mole of the
Boning Point<.1,_) _________________________ __ 441 ______ __ 428'
monohydroxy alcohol; 1n run Nos. 2 and 5 the reactants 10- Viscosity (Centlstokes) g..
were utilized in a ratio of 3.4 moles of the alkylene oxide
11-9
mixture per mole of the monohydroxy alcohol; in run
Rubber Sué'elling (percent) a ____ _
Nos. 3 and 6, the reactants were utilized in a ratio of
and Test
3.9 moles of the alkylene axide mixture per mole of
p31 (after) a‘. ................................ .. 10.13 .... _. 1033
the monohydroxy alcohol; and in run Nos. 4 and 7, the 15
____________________________ __ B?ghtnn Bright‘
reactants were utilized in a ratio of 4.4 moles of the
alkylene oxide mixture per mole of the monohydroxy
alcohol. The reactions were carried out and the pro
ducts recovered and subsequently evaluated as hydraulic
brake ?uids as described in Exam le 1. In this series
p
of experiments, the use of the corrosion inhibitor, anti-
B‘ras
20
___(10
""""""""""""""""""""" "3:33 """ "
Do.
B3:
rMe?sured at 130. F’
2 Measured at -40° F.
3 Measured using Manhattan Natural rubber, after 6 days at
21O= R
oxidant and lower alkylene glycol solvent was omitted.
?gs)? gfgz?giégt‘igé?‘éous mixture
The results obtained are tabulated below in Table B.
0 Measured “5,1511%
'
Table B
Run. Nos.
1
i
2
i
3
Boiling Point (° F.)__ 475
482
506
Viseosity(centi-
4.66 _____ __
5.4 ...... _-
4.27 ..... _-
sto1'es).1
4
5
6
7
e92
472
47';
492‘
5.87 _____ -_
4.34".--"
4.79 _____ __
5.4.
.
Viscorsitygcentl-
864 ...... __ 1,111.--.“ 1,510 ____ __ Freezes." 930 ...... -_
1,200 .... __
1,569.
2.41 ..... -_
2.71 ..... _-
3.03.
Clear and
Hazy and
stoxesl.
Rubber Swelling
(Percent).3
old Testl _________ ._ Clear and
Pours.
2.09_.--_-_
2.05__-____
Clear and
Hazy and __________ -_ Clear and
Pours.
2.25 ..... --
3.05 ..... --
Pours.
Pours.
Pours.
Pours.
I Measured at 130° F.
1 Measured at ~40° F.
I Measured using Manhattan Natural rubber, after 6 days at 210° F.
l Measured at --40° F.
From the above table, it can be seen that the hydraulic
EXAMPLE IV
brake ?uids obtained in run NOS. 1 t0 3 and 5 t0 7 meet
To a portion of the liquid composition obtained in run
existing SAE speci?cation and, advantageously, have boil- 50 No. 3 of Example II there were added with dissolution
ing points well in excess of 400° F. The ?uid of run No.
0.5 percent by weight of diphenylol propane and 0.25
4 on the other hand, containing substantially more than
percent by weight of the dibutyl amine dimer acid salt
5 oxyalkylene groups present per polyoxyalkylene glycol
of linoleic acid containing a 4 to 1 amine to acid mole
monoalkyl ether molecule, fails to meet SAE speci?ca-
ratio?‘ The Products W¢_1"¢_theH evaluated_ as hydraulic
lions. pglyoxyalkylene glycol monoalkyl ether comlmsi- 55 brake fluids in a manner sinnlar to that described in Exam
tions having unsatisfactory low temperature properties,
P1a 1' The results obtamed are tabulated below "1
as evidenced, for example, by freezing at a temperature
Table D‘
T bl D
of 0° F., were produced in a manner similar to that de-
. '
scribed above, using however, an alkylene oxide mixture
.
a
a
e
B?11mg_ Pomt (_ E)"; ------------------- --
510
containing
percent by 66
weight
percent
of 1,2-propylene
by weight of ethylene
oxide, and
oxide
by and
adding
34 60 $50051?
180051 Y- (centtlisttoléesgz
(Gen S 0“ es '-""""""""""""
"""""""""""" "
"'
,
_
_
_
Evaporation (percent residue) ______________ __
the alkylene oxide mixture to methanol in mole ratios of
pH (before)
pH (after)3
2.5110 1 and 4 t0 1.
EXAMPLE In
.
_
.00
Brass ______________________________ _.
Corrosion test (“lg/(3111-2 1055):‘1
Copper ---------------------------- —70
.
by werght of potassium tetraborate and 0.5 percent by
weight of diphenylol propane, based upon the total weight
of the resulting ?uid. The products were then evaluated
as hydraulic brake ?uids in a manner similar to that de- 75
Cast
St
1
ee
iron _________________ __
____
45-50
10.4
9.7
_____ __
65 Corrosion test (mg./cm.2loss):4
Tin
To portions of each of the liquid compositions obtained
in run Nos. 3 and 6 of Example H, there were added
approximately 2.5 percent by weight of ethylene glycol,
~
2.5 percent by weight
of dlethylene
glycol, 0.25- percent
3
""""" "
____
Aluminum _________________________ __
1 Mensa" d at 210, F
2 Measured at ~40’ F.
§5i§,=5ad§§,gi”§§3t ?queous mixture
.05
J3
01
'00
.
‘00
8,062,747
10
9
wherein said hydraulic brake ?uid consists essentially of
a poly(oxyethylene-oxy-1,2-propylene) glycol monoalkyl
EXAMPLE v
Various liquid poly(oxyethylene-oXy-1,2-propylene)
glycol monomethyl and monethyl ether compositions suit
ether (a) having an average molecular weight of from
about 175 to about 325, (b) in which there is present
able for use as high-boiling brake ?uids were prepared by
the reaction of a mixture containing 40 percent by weight
of ethylene oxide and 60 percent ‘by weight of 1,2-propyl
ene oxide with ethylene glycol monomethyl ether (run
an average of from about 3 to about 5 oxyalkylene groups
per molecule, (0) in which the oxyethylene groups are
present in a proportion of from about 50 percent to about
60 percent by weight based upon the total weight of the
oxyalkylene
groups present, and (d) in which the termi
No. 9) in a ratio of 4 moles of the alkylene oxide mix-,v
nal
alkyl
radical
is selected from the group consisting of
10
ture per mole of the monohydroxy alcohol. The reac
methyl and ethyl radicals.
tions were carried out and the products recovered and
No. 8) and with ethylene glycol monoethyl ether (run
subsequently evaluated as hydraulic brake ?uids as de
scribed in Example I. The results obtained are set forth
below in Table B.
3. In a method for applying pressure to a hydraulic
brake through a hydraulic brake ?uid, the improvement
wherein said hydraulic brake ?uid consists essentially of
15 at least about 90 percent by Weight of a poly(oxyethylene
oxy-LZ-propylene) glycol monoalkyl ether (a) having
an average molecular Weight of from about 175 to about
Table E
325, (b) in which there is present an average of from
about 3 to about 5 oxyalkylene groups per molecular,
20 (c) in which the oxyethylene groups and oxy-1,2-pro
pylene groups are each present in a proportion of from
about 35 percent to about 65 percent by weight based
Run Nos.
8
Boiling Point ° F ........................... .Viscosity (Centistokes) 1-..... ..
492 ...... ._
5.29 _____ ._
9
519.
5.26.
Viscosity (Oentist-okcs) Q"...
. 1,563 ____ __
1,663.
Rubber Swelling (percent) 3
Gold Test 4 ______________ ._
_
_
2.25 _____ __
Clear and
3.23.
Clear
_ _ . _ . __
Passes____
Evaporation Test (percent residue) __________ __
75 _______ __
\
Lubrication, Heat Stroke Test 6 _ _ _ _ _
and
Pours
Pours
1 Measured at 130° F.
1 Measured at —40° F.
3 Measured using Manhattan Natural rubber, after 6 days at 210° F.
upon the total weight of the oxyalkylene groups present,
and (d) in which the alkyl radical is selected from the
25 group consisting of methyl and ethyl radicals, the re
mainder of said hydraulic brake ?uid being a lower alkyl
ene glycol selected from the group consisting of ethylene
glycol, propylene glycol and mixtures thereof with a
member selected from the group consisting of diethylene
30 glycol and dipropylene glycol.
4. In a method for applying pressure to a hydraulic
brake through a hydraulic brake ?uid, the improvement
wherein said hydraulic brake‘ ?uid consists essentially of
‘ Measured after 6 hrs. at --60° F.
5 Measured at 70,000 strokes, under a pressure of 1,000 p.s.i., at 250° F
at least about 95 percent by weight of a poly(oxyethylene
35
From the above table, it can be seen that the hydraulic
brake ?uids of this invention meet existing SAE speci?
cations and, advantageously, have boiling points well in
excess of 400° F.
What is claimed is:
’
.
oxy-1,2-propylene) glycol monoalkyl ether (a) having
an average molecular weight of from about 175 to 325,
(b) in which there is present an average of from about
3 to about 5 oxyalkylene groups per molecule, (0) in
which the oxyethylene groups are present in a proportion
40 of from about 50 percent to about 60 mole percent by
weight based upon the total weight of the oxyalkylene
1. In a method for applying pressure to a hydraulic
brake through a hydraulic brake ?uid, the improvement
groups present, and (d) in which the terminal alkyl radi
wherein said hydraulic brake ?uid consists essentially of
cal is selected from the group consisting of methyl and
a poly(oXyethylene-oxy-l,2-propylene) glycol monoalkyl
ethyl radicals, the remainder of said hydraulic brake ?uid
ether (a) having an average molecular weight of from 45 being a lower alkylene glycol selected from the group
consisting of ethylene glycol, propylene glycol and mix~
about 175 to about 325, (b) in which there is present an
average of from about 3 to about 5 oxyalkylene groups
tures thereof with a member selected from the group
per molecule, (0) in which the oxyethylene groups and
consisting of diethylene glycol and dipropylene glycol.
oxy-l,2-propylene groups are each present in a propor
tion of from about 35 percent to about 65 percent by 50
weight, based upon the total weight of the oxyalkylene
groups present, and (d) in which the terminal alkyl
radical is selected from the group consisting of methyl
and ethyl radicals.
55
2. In a method for applying pressure to a hydraulic
brake through a hydraulic brake ?uid, the improvement
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,425,755
Roberts et al __________ __ Aug. 19, 1947 ‘
FOREIGN PATENTS
534,750
.
Canada -.._._, _________ __ Dec. 18, 1956
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