U.S. patent number 3,711,412 [Application Number 05/133,407] was granted by the patent office on 1973-01-16 for low-water sensitive hydraulic fluids containing borate esters and formals.
This patent grant is currently assigned to Olin Corporation. Invention is credited to David A. Csejka, Arthur W. Sawyer.
United States Patent |
3,711,412 |
Sawyer , et al. |
January 16, 1973 |
LOW-WATER SENSITIVE HYDRAULIC FLUIDS CONTAINING BORATE ESTERS AND
FORMALS
Abstract
This invention relates to a low water-sensitive hydraulic fluid
composition which contains from about 20 to about 96 percent by
weight of at least one borate ester as the base fluid and
additionally, from about 2 to about 40 percent of a bis (glycol
ether) formal. Such low water-sensitive hydraulic fluids are high
boiling compositions which also have desirable properties at low
temperatures, particularly viscosity, and thus are useful under a
wide variety of climatic and operational conditions.
Inventors: |
Sawyer; Arthur W. (Hamden,
CT), Csejka; David A. (Orange, CT) |
Assignee: |
Olin Corporation (N/A)
|
Family
ID: |
27585215 |
Appl.
No.: |
05/133,407 |
Filed: |
April 12, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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717996 |
Apr 1, 1968 |
3625899 |
|
|
|
653338 |
Jul 14, 1967 |
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Current U.S.
Class: |
252/75; 252/78.5;
252/78.1; 508/199 |
Current CPC
Class: |
C10M
125/20 (20130101); C10M 133/40 (20130101); C10M
107/34 (20130101); C10M 145/28 (20130101); C10M
169/044 (20130101); F02M 1/00 (20130101); C10M
145/36 (20130101); C10M 3/00 (20130101); C07F
5/04 (20130101); C10M 111/04 (20130101); C10M
105/78 (20130101); C10M 133/08 (20130101); C10M
145/26 (20130101); C10M 125/26 (20130101); C10M
111/04 (20130101); C10M 105/78 (20130101); C10M
107/34 (20130101); C10M 133/08 (20130101); C10M
133/40 (20130101); C10M 145/26 (20130101); C10M
169/04 (20130101); C10M 105/78 (20130101); C10M
107/34 (20130101); C10M 125/20 (20130101); C10M
125/26 (20130101); C10M 169/04 (20130101); C10M
105/78 (20130101); C10M 125/20 (20130101); C10M
133/08 (20130101); C10M 145/28 (20130101); C10M
145/36 (20130101); C10M 2207/024 (20130101); C10M
2209/1033 (20130101); C10M 2215/066 (20130101); C10M
2215/30 (20130101); C10M 2227/0625 (20130101); C10N
2020/01 (20200501); C10M 2201/083 (20130101); C10M
2201/087 (20130101); C10M 2209/104 (20130101); C10M
2209/1085 (20130101); C10M 2215/062 (20130101); C10M
2219/085 (20130101); C10M 2209/1045 (20130101); C10M
2207/129 (20130101); C10M 2207/08 (20130101); C10M
2207/284 (20130101); C10M 2215/22 (20130101); C10M
2207/022 (20130101); C10M 2223/043 (20130101); C10M
2207/282 (20130101); C10M 2209/103 (20130101); C10M
2217/028 (20130101); C10M 2201/102 (20130101); C10M
2207/023 (20130101); C10M 2209/1095 (20130101); C10M
2201/08 (20130101); C10M 2209/1065 (20130101); C10M
2215/067 (20130101); C10M 2223/042 (20130101); C10M
2207/046 (20130101); C10M 2209/106 (20130101); C10M
2209/1075 (20130101); C10M 2215/226 (20130101); C10M
2219/108 (20130101); C10M 2219/09 (20130101); C10M
2215/044 (20130101); C10M 2201/081 (20130101); C10M
2215/26 (20130101); C10M 2219/088 (20130101); C10N
2040/08 (20130101); C10M 2201/084 (20130101); C10M
2207/04 (20130101); C10M 2215/225 (20130101); C10M
2215/064 (20130101); C10M 2217/06 (20130101); C10M
2219/044 (20130101); C10N 2030/12 (20130101); C10M
2215/224 (20130101); C10M 2219/087 (20130101); C10M
2223/041 (20130101); C10M 2201/082 (20130101); C10M
2209/108 (20130101); C10M 2207/18 (20130101); C10M
2207/34 (20130101); C10M 2215/14 (20130101); C10M
2217/046 (20130101); C10M 2215/06 (20130101); C10M
2215/221 (20130101); C10M 2209/107 (20130101); C10M
2207/025 (20130101); C10M 2209/1055 (20130101); C10M
2215/042 (20130101); C10M 2207/021 (20130101); C10M
2207/026 (20130101); C10M 2207/125 (20130101); C10M
2215/04 (20130101); C10M 2215/065 (20130101); C10M
2201/085 (20130101); C10M 2207/20 (20130101); C10M
2207/285 (20130101); C10M 2219/082 (20130101); C10M
2209/105 (20130101); C10M 2219/089 (20130101); C10M
2209/109 (20130101); C10M 2215/18 (20130101); C10M
2223/04 (20130101); C10M 2227/062 (20130101); C10M
2227/0615 (20130101); C10M 2201/10 (20130101); C10M
2201/105 (20130101); C10M 2227/061 (20130101) |
Current International
Class: |
C10M
111/00 (20060101); C10M 111/04 (20060101); C10M
169/00 (20060101); C10M 169/04 (20060101); C07F
5/00 (20060101); C07F 5/04 (20060101); F02M
1/00 (20060101); C09k 003/00 (); C10m 003/48 () |
Field of
Search: |
;252/73,75,78,49.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosdol; Leon D.
Assistant Examiner: Silverstein; D.
Parent Case Text
This application is a continuation-in-part of copending application
Ser. No. 717,996 filed Apr. 1, 1968 and now U.S. Pat. No. 3,625,899
which in turn was a continuation-in-part of application Ser. No.
653,338 filed July 14, 1967 and now abandoned.
Claims
What is claimed is:
1. A hydraulic fluid composition consisting essentially of (A) from
about 20 to about 96 percent by weight, based on the total weight
of the hydraulic fluid composition, of at least one base fluid or
lubricant selected from the group consisting of (a) a borate ester
of the formula:
[R.sub.1 (O--R.sub.a).sub.y -O].sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.a
is alkylene of from two to four carbon atoms and y is an integer of
from 2 to 4; (b) a borate ester of the formula:
[R.sub.1 --(OCH.sub.2 CHR.sub.2).sub.m --(OCH.sub.2
CHR.sub.3).sub.n O].sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.2
and R.sub.3 are independently selected from the group consisting of
hydrogen and methyl, m and n are positive integers whose sum is
from 2 to 20, and with the proviso that one of R.sub.2 and R.sub.3
is methyl and one of R.sub.2 and R.sub.3 is hydrogen; (c) a borate
ester of the formula:
(R.sub.1 [R.sub.g ]O).sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.g
is a heteric oxyalkylene chain of the formula:
[-- (OCH.sub.2 CH.sub.2).sub.r , (OCH.sub.2 CHCH.sub.3).sub.s --]
,
wherein the sum of r and s is not more than 20 and wherein the
weight percent of the oxyethylene units is not less than 20 based
on the total weight of all the oxyalkylene units; and (d) a borate
ester of the formula: ##SPC5##
wherein T.sub.1, T.sub.2 and T.sub.3 are each an independently
selected alkyl group having from one to four carbon atoms, R.sub.4,
R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are independently
selected from the group consisting of hydrogen and methyl, n and m
are positive integers independently selected in each chain and
whose sum in each chain is from 2 to 20, and with the proviso that
in no more than two of the chains is the sum of n and m the
same;(B) from about 2 to about 40 percent by weight, based on the
total weight of the hydraulic fluid composition, of at least one
bis(glycol ether) formal having the formula:
[R.sub.b O(R.sub.a O).sub.x ].sub.2 CH.sub.2 ,
wherein R.sub.b is alkyl of one to six carbon atoms, R.sub.a is
alkylene of two to four carbon atoms and x is an integer of 1 to 5
and (C) from 0 to about 78 percent by weight, based on the total
weight of the fluid composition, of at least one diluent selected
from the group consisting of: (aa) glycol ethers having the
formula:
R[O-R"].sub.y OR' ,
wherein R is alkyl of from one to four carbon atoms, R' is selected
from the group consisting of hydrogen and alkyl of from one to four
carbon atoms, R" is alkylene of from two to four carbon atoms and y
is an integer of from 2 to 4; (bb) glycols and polyglycols having a
molecular weight of from about 60 to about 450 and (cc) aliphatic
saturated monohydric alcohols having from six to 13 carbon
atoms.
2. The hydraulic fluid composition of claim 1 wherein said formal
has an alkyl R.sub.b group of one to four carbon atoms, an alkylene
R.sub.a group of two to three carbon atoms and x is 1 to 3.
3. The hydraulic fluid composition of claim 2 wherein from about 2
to about 15 percent by weight, based on the total weight of the
hydraulic fluid, of said formal is present.
4. The hydraulic fluid composition of claim 3 wherein said formal
is selected from the group consisting of: [CH.sub.3 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.3
].sub.2 CH.sub.2, [C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.2
].sub.2 CH.sub.2, [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O)].sub.2
CH.sub.2, and [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2
CH.sub.2.
5. The hydraulic fluid composition of claim 2 wherein said base
fluid or lubricant is a borate ester of type (a).
6. The hydraulic fluid composition of claim 5 wherein said base
fluid or lubricant consists essentially of from about 20 to about
54.4 percent by weight, based on the total weight of the hydraulic
fluid composition.
7. The hydraulic fluid composition of claim 5 wherein said base
fluid or lubricant consists essentially of from about 54.5 to about
92 percent by weight, based on the total weight of the hydraulic
fluid composition.
8. The hydraulic fluid composition of claim 7 wherein said borate
ester of type (a) has an alkyl R.sub.1 group of one to two carbon
atoms and an R.sub.a alkylene group of two to three carbon
atoms.
9. The hydraulic fluid composition of claim 7 wherein said base
fluid or lubricant is a borate ester selected from the group
consisting of: [CH.sub.3 (OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B,
[C.sub.2 H.sub.5 (OCH.sub.2 CH.sub.2).sub.2 O].sub.3 --B, [C.sub.2
H.sub.5 (OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B, [C.sub.2 H.sub.5
(OCH.sub.2 CH.sub.2).sub.4 O].sub.3 --B, [C.sub.3 H.sub.7
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B, [C.sub.4 H.sub.9
(OCH.sub.2 CH.sub.2).sub.2 O].sub.3 --B and [C.sub.4 H.sub.9
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B.
10. The hydraulic fluid composition of claim 9 wherein from about 2
to about 15 percent by weight, based on the total weight of the
hydraulic fluid composition, of said formal is used.
11. The hydraulic fluid composition of claim 10 wherein said formal
is selected from the group consisting of: [CH.sub.3 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.2
].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2
CH.sub.2, [C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2
CH.sub.2, [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2 and
[C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2 CH.sub.2.
12. The hydraulic fluid composition of claim 11 wherein said
diluent is present in amounts of from about 2 to about 70 percent
by weight, based on the total weight of the hydraulic fluid
composition.
13. The hydraulic fluid composition of claim 12 wherein said
diluent is selected from the group consisting of diethylene glycol
monomethyl ether, diethylene glycol monoethyl ether, diethylene
glycol monobutyl ether, triethylene glycol monomethyl ether,
triethylene glycol monoethyl ether, triethylene glycol monobutyl
ether, tetraethylene glycol monomethyl ether and tetraethylene
glycol monobutyl ether.
14. The hydraulic fluid composition of claim 13 wherein from about
0.2 to about 6.0 percent by weight of an inhibitor for pH and
corrosion control is used.
15. The hydraulic fluid composition of claim 14 wherein said
inhibitor is selected from the group consisting of glycerin,
butynediol, diethanolamine, methyl diethanolamine, mixed
isopropanolamines, diisopropanolamine and triisopropanolamine.
16. The hydraulic fluid composition of claim 15 wherein from about
0.001 to about 1.0 percent by weight, based on the total weight of
the hydraulic fluid composition, of an antioxidant is used.
17. The hydraulic fluid composition of claim 16 wherein said
antioxidant is selected from the group consisting of sodium nitrite
and dioctyl diphenylamine.
18. The hydraulic fluid composition of claim 5 wherein said diluent
is a glycol ether of type (aa).
19. The hydraulic fluid composition of claim 18 wherein said
diluent is present in amounts of from about 2 to about 70 percent
by weight, based on the total weight of the hydraulic fluid
composition.
20. The hydraulic fluid composition of claim 19 wherein said
diluent is selected from the group consisting of:
diethylene glycol monomethyl ether, diethylene glycol monoethyl
ether, diethylene glycol monobutyl ether, triethylene glycol
monomethyl ether, triethylene glycol monoethyl ether, triethylene
glycol monobutyl ether, tetraethylene glycol monomethyl ether and
tetraethylene glycol monobutyl ether.
21. The hydraulic fluid composition of claim 20 wherein said formal
is selected from the group consisting of: [CH.sub.3 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2. [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.2
].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2
CH.sub.2, [C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2
CH.sub.2, [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2,
and [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2
CH.sub.2.
22. The hydraulic fluid composition of claim 18 having incorporated
therein from 0 to about 8.0 percent by weight, based on the total
weight of the hydraulic fluid composition, of an inhibitor additive
for pH and corrosion control.
23. The hydraulic fluid composition of claim 22 wherein from about
0.2 to 6.0 percent by weight of said inhibitor is used.
24. The hydraulic fluid composition of claim 23, wherein said
inhibitor is selected from the group consisting of: glycerin,
butynediol, diethanolamine, methyl diethanolamine, mixed
isopropanolamines, diisopropanolamine and triisopropanolamine.
25. The hydraulic fluid composition of claim 22 wherein from 0 to
about 2 percent by weight, based on the total weight of the
hydraulic fluid composition, of an antioxidant additive is
incorporated therein.
26. The hydraulic fluid composition of claim 25 wherein from about
0.001 to about 1.0 percent by weight of said antioxidant is
used.
27. The hydraulic fluid composition of claim 26 wherein said
antioxidant is selected from the group consisting of sodium nitrite
and dioctyl diphenylamine.
28. The hydraulic fluid composition of claim 27 wherein said
inhibitor is selected from the group consisting of glycerin,
butynediol, diethanolamine, methyl diethanolamine, mixed
isopropanolamines, diisopropanolamines and triisopropanolamine.
29. The hydraulic fluid composition of claim 28 wherein said formal
is selected from the group consisting of [CH.sub.3 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.2
].sub.2 CH.sub.2, [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2
CH.sub.2, [C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2
CH.sub.2, [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2 and
[C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3 ].sub.2 CH.sub.2.
30. In the operation of a fluid pressure operating device which
uses hydraulic pressure transmission fluid, the improvement
comprising using as said hydraulic pressure transmission fluid, a
composition consisting essentially of (A) a borate ester base fluid
selected from the group consisting of (a) a borate ester of the
formula:
[R.sub.1 (O--R.sub.a).sub.y --O].sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.a
is alkylene of from two to four carbon atoms and y is an integer of
from 2 to 4; (b) a borate ester of the formula:
[R.sub.1 --(OCH.sub.2 CHR.sub.2).sub.m --(OCH.sub.2
CHR.sub.3).sub.n O].sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.2
and R.sub.3 are independently selected from the group consisting of
hydrogen and methyl, m and n are positive integers whose sum is
from 2 to 20, and with the proviso that one of R.sub.2 and R.sub.3
is methyl and one of R.sub.2 and R.sub.3 is hydrogen; (c) a borate
ester of the formula:
(R.sub.1 [R.sub.g ]O).sub.3 --B ,
wherein R.sub.1 is alkyl of from one to four carbon atoms, R.sub.g
is a heteric oxyalkylene chain of the formula:
[-- (OCH.sub.2 CH.sub.2).sub.r , (OCH.sub.2 CHCH.sub.3).sub.s --]
,
wherein the sum of r and s is not more than 20 and wherein the
weight percent of the oxyethylene units is not less than 20 based
on the total weight of all the oxyalkylene units; and (d) a borate
ester of the formula: ##SPC6##
wherein T.sub.1, T.sub.2 and T.sub.3 are each an independently
selected alkyl group having from one to four carbon atoms; R.sub.4,
R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are independently
selected from the group consisting of hydrogen and methyl, n and m
are positive integers independently selected in each chain and
whose sum in each chain is from 2 to 20, and with the proviso that
in no more than two of the chains is the sum of n and m the same;
and (B) from about 2 to about 40 percent by weight, based on the
total weight of the hydraulic fluid composition, of at least one
bis(glycol ether) formal having the formula:
[R.sub.b O(R.sub.a O).sub.x ].sub.2 CH.sub.2 ,
wherein R.sub.b is alkyl of one to six carbon atoms, R.sub.a is
alkylene of two to four carbon atoms and x is an integer of 1 to
5.
31. The process of claim 30 wherein there is from about 2 to about
15 percent by weight, based on the total weight of the hydraulic
fluid composition, of said formal.
32. The process of claim 31 wherein there is from about 20 to about
96 percent by weight, based on the total weight of the hydraulic
fluid composition, of said base fluid.
Description
This invention relates to new and improved, low water-sensitive
hydraulic pressure transmission fluids for use in fluid pressure
operating devices such as hydraulic brake systems, hydraulic
steering mechanisms, hydraulic transmissions, hydraulic jacks,
hydraulic lifts, etc. More particularly, this invention relates to
hydraulic fluids having a low sensitivity to water which employ as
the base fluid one or more borate esters of glycol monoethers and
additionally a bis (glycol ether) formal. The term "base fluid" as
used throughout the specification and claims means the major active
ingredient (not necessarily present in the major or largest
proportion) of the hydraulic fluid, i.e., that ingredient which is
most active in maintaining the desired properties of the hydraulic
fluid especially in the face of aqueous contamination.
A great number of hydraulic fluid compositions have been suggested
in the art. Commonly, the hydraulic pressure transmission fluids,
such as brake fluids are made up of three principal units. The
first is a base stock or lubricant for the system which may include
heavy bodied fluids such as polyglycols, castor oil, mixtures of
these materials, etc. Diluents, which are employed for the purpose
of controlling the viscosity of the fluid as represented by glycol
ethers, glycols, alcohols, etc., form the second basic unit.
Finally, the third basic unit is represented by an additive or
inhibitor package comprising small quantities of materials which
are added to control or modify various chemical and physical
properties of the fluid, e.g., to reduce oxidation, to improve
wetting and flow and to maintain the pH of the hydraulic system
above 7 in order to minimize corrosion. By varying the composition,
particularly desired properties can generally be attained. However,
hydraulic fluids have been subject to increasingly stringent
requirements with regard to properties, particularly boiling point
and viscosity-temperature relationship. This had made it extremely
difficult to produce a desirable fluid since very often a change in
composition which improves one or more of the properties will
detrimentally affect some other property. Thus, it has been
possible to obtain hydraulic fluids having high boiling points by
using higher molecular weight organic compounds, such as the
polyoxyalkylene glycol ethers, as the major component, however, the
viscosity of these fluids is generally unsatisfactory, particularly
at low temperatures. This problem is magnified when water gets into
the hydraulic fluid since many of the properties are affected, some
to a substantial extent.
Hydraulic fluids, as exemplified by the commercial motor vehicle
brake fluids, are hygroscopic by nature and therefore, absorb
moisture from ambient atmospheres with resulting degradation of
their boiling point. This effect that water has on the boiling
point of hydraulic fluids has been studied extensively and a great
deal of public interest has been generated concerning the safety
qualities of hydraulic fluids especially brake fluids as is pointed
out, for example by C. F. Pickett in an article entitled
"Automotive Hydraulic Brake Fluids" published as part of the 51st
Mid-Year Meeting Proceedings of the Chemical Specialties
Manufacturing Association, Inc., N.Y. (1965). As indicated in the
above-noted article, when small amounts of water, e.g., 3.5 percent
by weight was added to various commercial brake fluids, some having
initial boiling points of 500.degree. F., the resulting fluid
compositions exhibited boiling points below 300.degree. F. In
contrast, the hydraulic fluid compositions of this invention
generally maintain boiling points of greater than 300.degree. F.
and more often greater than 320.degree. F. and 350.degree. F. when
preferred embodiments are used, after the addition of 3.5 percent
water.
The importance of having a hydraulic fluid which has a low
sensitivity to water and thus can maintain the boiling point at
levels above those previously found in available commercial fluids
is more readily understood when the following facts are considered.
First of all, it is known that hydraulic brake fluid temperatures
can reach rather high levels and often approach and even exceed the
300.degree. F. level. This is substantiated by the results of field
studies in 1966 by the Society of Automotive Engineers (See SP-338,
"Automotive Brake Evaluation Under Customer Usage Conditions," pp.
1 and 2, (1968)) wherein it was shown that brake fluid temperatures
approached 270.degree. F. under typical driving conditions of
vehicles which were loaded only to their manufacturer's recommended
limit. It could reasonably be assumed from these results, that when
abnormal conditions are encountered temperatures would exceed
270.degree. F. and approach and even pass 300.degree. F.
It is also known that so-called conventional type motor vehicles
often accumulate small amounts of moisture in their hydraulic
fluids during usage. This is substantiated by results disclosed in
a meeting of the SAE Hydraulic Brake Systems Actuating Committee in
1966 (See minutes of meeting of Oct. 26-27, 1966) and further by
the report of Charles B. Jordan, "Effect of Water on Hydraulic
Brake Fluid," U.S. Army Coating and Chemical Laboratory, May, 1966.
These articles clearly show that amounts of water have been
accumulated in hydraulic brake fluids under use conditions in
varying proportions and have often reached levels of up to 3.5
percent and even have been as high as 5 percent by weight. The fact
that hydraulic fluids do accumulate some water during usage is
further supported by the SAE Standard J-1703, Motor Vehicle Brake
Fluid, which requires certain water tolerance tests to be passed
after the addition of 3.5 percent water and also, requires a
corrosion test to be passed after the addition of 5 percent water
to the brake fluid.
From the above discussion, it can readily be understood that
hydraulic fluids under certain conditions can approach temperatures
of the magnitude of 300.degree. F. and higher and furthermore such
fluids can accumulate small amounts of moisture during usage. Thus,
hydraulic fluids which have low dry boiling points and are
sensitive to water to a large degree can encounter problems such as
vapor lock which can result in the failure of a hydraulic brake
system and consequently cause an accident. This clearly illustrates
the advantage of the hydraulic fluids of this invention which
possess a high degree of water tolerance and are able to maintain
their boiling points at higher and safer levels.
The seriousness of the problem of water accumulation and its
effects on the hydraulic fluid system is further signified by the
fact that the U.S. Department of Transportation presently is
considering acceptance of standards for motor vehicle brake fluids
which would for the first time include a minimum wet reflux boiling
point (equivalent to approximately 3.5 percent by weight of water
added). The proposed standards include one for a fluid having a
minimum dry reflux boiling point of 401.degree. F. and a minimum
wet reflux boiling point of 284.degree. F. and another for a fluid
having a minimum dry reflux boiling point of 446.degree. F. and a
minimum wet reflux boiling point of 320.degree. F. The term "dry
reflux boiling point" as used herein is defined as the boiling
point of the hydraulic fluid as delivered to the consumer or
distributors (i.e., fluid ready for use). Wet reflux boiling point
is the boiling point of the hydraulic fluid after a discrete amount
of water has been added thereto.
The above considerations clearly point out the need for a hydraulic
fluid which has a low sensitivity to water and thus is able to
maintain certain properties and characteristics when amounts of
water commonly encountered during use are present. In addition, a
hydraulic fluid which will be used under various climatic and
operational conditions must maintain adequate viscosity (fluidity)
over the temperature range of anticipated operating conditions so
as to assure proper functionality of the system.
There are various hydraulic fluids known in the art as shown for
example in Introduction to Hydraulic Fluids by Roger E. Hatton,
Reinhold Publishing Corp. (1962); U.S. Pat. No. 2,998,389 issued to
Chester M. White on Aug. 29, 1961 and U.S. Pat. No. 3,377,288
issued to Arthur W. Sawyer on Apr. 9, 1968. Generally, these fluids
do not have the low water sensitivity that is required to maintain
their original properties after there is an accumulation of
moisture and additionally such fluids generally do not have the
ability to operate under a wide variation of conditions.
One of the basic objects of this invention is to provide hydraulic
pressure transmission fluids for use in hydraulic systems which
retain to a high degree their original properties when water is
added, i.e., they have a low sensitivity to water.
Another object is to provide hydraulic pressure transmission fluids
which are high boiling compositions and which maintain relatively
high boiling points even when water is added to the initial fluid
composition.
Another object of this invention is to provide hydraulic pressure
transmission fluids having a high degree of lubricity while
maintaining desired viscosities within a predetermined range under
wide variations of temperature conditions, especially subfreezing
temperatures.
The hydraulic fluids of this invention generally comprise from
about 20 to about 96 percent by weight, based on the total
hydraulic fluid weight, of at least one borate ester of a glycol
monoether as the base fluid and from about 2 to about 40 percent by
weight of a formal of the glycol ethers. Generally the remainder of
the fluid is made up of diluent and one or more additives.
The hydraulic fluids of this invention are especially desirable
because they have a low water-sensitivity and also have a desired
viscosity-temperature relationship over a wide range of temperature
conditions. These properties make such fluids particularly
attractive because they can satisfactorily perform at low winter
temperatures where the viscosity requirements are stringent and
also can be used in warm weather climates and under heavy duty
conditions particularly because of their high boiling points and
low sensitivity to water. Additionally, the hydraulic fluids of
this invention are of low cost, are essentially odorless and
colorless, possess a high degree of compatibility with other fluids
and exhibit a very low rate of corrosivity.
Another feature of the hydraulic fluids of this invention is that
they have a satisfactory rubber compatibility. The significance of
rubber compatibility and the rubber swelling properties of the
fluids cannot be overlooked since too little swelling will result
in leakage of the fluid passed the rubber cup sealing means and
passed the piston and hydraulic cylinders with corresponding loss
of power. On the other hand, fluids which cause too much rubber
swelling are not desirable since they destroy the structural
properties of the rubber sealing cups and rubber cylinders which,
in turn, results in malfunction or inoperativeness of the unit.
The hydraulic fluids of this invention generally comprise four
principal units: (1) base fluid, (2) formal, (3) diluent and (4)
additives.
BASE FLUID
The base fluid employed in the novel hydraulic fluids of this
invention generally comprises at least one borate ester of a glycol
monoether. More particularly, the hydraulic fluids of this
invention will comprise from about 20 to about 96 percent by
weight, based on the total hydraulic fluid weight, of at least one
borate ester of a glycol monoether. Preferably, the amount of
borate ester will vary from about 30 to about 92 percent and more
preferably from about 54.5 to about 92 percent by weight based on
the total hydraulic fluid weight. When using hydraulic fluids which
can safely operate under somewhat lower temperature conditions, the
range of borate ester used may vary from about 20 to about 54.4
percent and preferably from about 30 to about 54.4 percent by
weight, based on the total weight of the hydraulic fluid.
Although a wide variety of borate esters can be employed as the
base fluid in the novel hydraulic fluids of this invention, an
especially useful class of borate esters are the so-called
tri-borate esters of glycol monoethers having the general
formula:
[R.sub.1 (O--R.sub.a).sub.y --O].sub.3 --B ,
wherein R.sub.1 is a lower alkyl radical containing from one to
four carbon atoms preferably one to two, R.sub.a is alkylene of
from two to four carbon atoms, preferably two to three, and y is an
integer from 2 to 4 inclusive. The R.sub.1 and R.sub.a groups may
be either straight or branched chain structures. Borates of the
above-mentioned type include, for example: [CH.sub.3 (OCH.sub.2
CH.sub.2).sub.2 O].sub.3 --B, [C.sub.2 H.sub.5 (OCH.sub.2
CH.sub.2).sub.3 O].sub.3 --B, [C.sub.3 H.sub.7 (OCH.sub.2
CH.sub.2).sub.4 O].sub.3 --B, [CH.sub.3 (OCH.sub.2
CHCH.sub.3).sub.2 O].sub.3 --B, [CH.sub.3 (OCH.sub.2
CHCH.sub.3).sub.3 O].sub.3 --B, [CH.sub.3 (OCH.sub.2
CHCH.sub.3).sub.4 O].sub.3 --B, [C.sub.2 H.sub.5 (OCH.sub.2
CHCH.sub.3).sub.2 O].sub.3 --B, [C.sub.2 H.sub.5 (OCH.sub.2
CHCH.sub.3).sub.3 O].sub.3 --B, [C.sub.2 H.sub.5 (OCH.sub.2
CHCH.sub.3).sub.4 O].sub.3 --B, [C.sub.3 H.sub.7 (OCH.sub.2
CHCH.sub.3).sub.2 --.sub.4 O].sub.3 --B, [C.sub.4 H.sub.9
(OCH.sub.2 CHCH.sub.3).sub.2 --.sub.4 O].sub.3 --B, [CH.sub.3
O(OCHCH.sub.3 CH.sub.2).sub.2 --.sub.4 O].sub.3 --B, [C.sub.2
H.sub.5 (OCHCH.sub.3 CH.sub.2).sub.2 --.sub.4 O].sub.3 --B,
[CH.sub.3 (OCHCH.sub.3 CHCH.sub.3).sub.2 --.sub.4 O].sub.3 --B,
[C.sub.2 H.sub.5 (OCHCH.sub.3 CHCH.sub.3).sub.2 --.sub.4 O].sub.3
--B, [CH.sub.3 (OCH.sub.2 CHCH.sub.2 CH.sub.3).sub.2 --.sub.4
O].sub.3 --B, [C.sub.2 H.sub.5 (OCH.sub.2 CHCH.sub.2
CH.sub.3).sub.2 --.sub.4 O].sub.3 --B,
while any of the borate esters defined by formula (I) may be used,
the following borate esters are particularly useful: [CH.sub.3
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B, [C.sub.2 H.sub.5
(OCH.sub.2 CH.sub.2).sub.2 O].sub.3 --B, [C.sub.2 H.sub.5
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B, [C.sub.2 H.sub.5
(OCH.sub.2 CH.sub.2).sub.4 O].sub.3 --B, [C.sub.3 H.sub.7
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B, [C.sub.4 H.sub.9
(OCH.sub.2 CH.sub.2).sub.2 O].sub.3 --B and [C.sub.4 H.sub.9
(OCH.sub.2 CH.sub.2).sub.3 O].sub.3 --B.
Borates of the above-mentioned type can be conveniently prepared by
reacting orthoboric acid and the glycol monoether while in the
presence of a water-azeotrope forming solvent. Water formed in the
esterification reaction is continuously removed as the azeotrope.
At first, the temperature of the reaction mixture is maintained
between about 0.degree. C. and about 190.degree. C. and desirably
at the distillation temperature of the water-solvent azeotrope.
After essentially complete removal of the water formed during
esterification, the excess solvent is conveniently removed from the
reaction mixture by distillation. The borate ester product, which
is left in a residue, may then be recovered by distilling under
reduced pressure or by extraction with a suitable solvent followed
by evaporation of the solvent. For example, the compound [C.sub.2
H.sub.5 (OCH.sub.2 CH.sub.2).sub.2 O].sub.3 --B can be prepared by
reacting two moles of C.sub.2 H.sub.5 (OCH.sub.2 CH.sub.2).sub.2
OH, 0.67 mole of orthoboric acid and 700 ml. of ethylbenzene with
heating and mixing to yield 198 grams of the ester, a water-white
liquid boiling at 222.degree.-223.degree. C. (5 mm. Hg). It is
noted that in the preparation of these esters, a small proportion
of concomitant reaction products may be formed and other minor
impurities may also be present. Generally, the predominant portion
of such other reaction products formed will be a boroxine type
compound having the following general structure: ##SPC1##
wherein R.sub.z is derived from the particular glycol ether being
used, e.g., CH.sub.3 (OCH.sub.2 CH.sub.2).sub.2 O--, C.sub.2
H.sub.5 (OCH.sub.2 CH.sub.2).sub.2 O--, etc. The amount of such
concomitant reaction products formed and other impurities present
may be up to about 10 percent by weight if the reacted mixture is
not distilled. Distillation will reduce the amount of other
reaction products and impurities to about 1 percent or less,
however, either the distilled or undistilled product can be used
provided the reaction medium or solvent is stripped off. The term
"borate ester" as used in the specification and claims is intended
to include relatively pure borate ester as well as crude borate
ester which contains impurities and other by-products formed during
preparation as described above. The preparation of the tri-borate
esters per se is more completely described in U. S. Pat. No.
3,080,412 issued to D. M. Young on Mar. 5, 1963. It is of interest
to note that this patent (U.S. Pat. No. 3,080,412) discloses the
use of tri-borate esters, such as tris [2--(2-ethoxyethoxy)ethyl]
borate, as stabilizers and corrosion inhibitors for lubricants and
non-aqueous hydraulic fluids. However, use of these esters for such
purposes, i.e., as a stabilizer or corrosion inhibitor, would not
impart satisfactory low water sensitivity to the hydraulic fluid
since such usage would generally be in very small or minor
proportions (e.g., from 0.5 to 2 percent) in accordance with the
generally accepted practice in the art (e.g., see U.S. Pat. No.
3,403,104 issued to P. B. Sullivan on Sept. 24, 1968). Additionally
fluids containing such amounts of esters would not have desired
temperature-viscosity relationship over the wide range of operating
conditions as provided by the hydraulic fluids of this
invention.
A second highly useful class of borate esters includes compounds of
the general formula: [R.sub.1 --(OCH.sub.2 CHR.sub.2).sub.m
--(OCH.sub.2 CHR.sub.3).sub.n O].sub.3 --B (II)
wherein R.sub.2 and R.sub.3 are independently selected from the
group consisting of hydrogen and methyl, m and n are positive
integers whose sum is from 2 to 20 and R.sub.1 is alkyl of from one
to four carbon atoms and with proviso that one of R.sub.2 and
R.sub.3 is methyl and one of R.sub.2 and R.sub.3 is hydrogen.
R.sub.1 may be a straight chain or branched alkyl. Borate esters of
Type II can be prepared in the general way as those esters
previously described (Type I) above, utilizing the so-called block
type glycol monoethers. The preparation of esters of Type II is
described in detail in U.S. Pat. No. 3,316,287 issued to L. G.
Nunn, Jr. et al. on Apr. 25, 1967.
Type II borate esters useful in preparing the novel fluids of this
invention include, for example:
[CH.sub.3 (OCH.sub.2 CH.sub.2)--(OCH.sub.2 CHCH.sub.3)O].sub.3
--B
[c.sub.2 h.sub.5 (och.sub.2 chch.sub.3)--(och.sub.2
ch.sub.2)o].sub.3 --b
[c.sub.3 h.sub.7 (och.sub.2 chch.sub.3).sub.2 --(och.sub.2
ch.sub.2)o].sub.3 --b
[c.sub.4 h.sub.9 (och.sub.2 ch.sub.2).sub.5 --(och.sub.2
chch.sub.3)o].sub.3 --b
[ch.sub.3 (och.sub.2 ch.sub.2).sub.8 --(och.sub.2 chch.sub.3).sub.5
o].sub.3 --b
[c.sub.2 h.sub.5 (och.sub.2 chch.sub.3).sub.12 --(och.sub.2
ch.sub.2).sub.8 o].sub.3 --b
[c.sub.3 h.sub.7 (och.sub.2 chch.sub.3).sub.10 --(och.sub.2
ch.sub.2).sub.3 --b
another class of borate esters useful in the fluid compositions of
this invention include esters having heteric oxyalkylene chains,
that is, oxyalkylene chains in which oxyethylene and oxypropylene
units are distributed randomly throughout the chain. These Type III
esters have the general formula:
(R.sub. 1 [Rg]O).sub.3 --B , (III)
Rg represents a heteric oxyalkylene chain having the formula:
[--(OCH.sub.2 CH.sub.2).sub.R , (OCH.sub.2 CHCH.sub.3).sub.s
--]
where the sum of r and s is not more than 20 and wherein the weight
percent of oxyethylene units in the said chain is not less than 20
based on the total weight of all the oxyalkylene units in the chain
and R.sub.1 is alkyl of from one to four carbon atoms and may be
straight or branched chain. The preparation of Type III esters can
be accomplished in the same general manner as the preparation of
Types I and II described above by reacting orthoboric acid in the
presence of toluene with a heteric glycol monoether of the
formula:
R.sub.1 [Rg]OH ,
where R.sub.1 and Rg have the same meaning as previously set forth.
Glycol monoethers of this class can be conveniently prepared by
methods well known in the art such as the process described in U.S.
Pat. No. 2,425,845 issued to W. J. Toussaint et al. on Aug. 19,
1947.
A fourth type of borate ester suitable for use in the fluid
compositions of this invention have the general formula:
##SPC2##
wherein T.sub.1, T.sub.2 and T.sub.3 are each an independently
selected alkyl group having from one to four carbon atoms, R.sub.4,
R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are independently
selected from the group consisting of hydrogen and methyl, n and m
are positive integers independently selected in each chain and
whose sum in each chain is from 2 to 20, and with the proviso that
in no more than two of the chains is the sum of n and m the same.
It is also noted that T.sub.1, T.sub.2, and T.sub.3 may be a
straight or branched chain alkyl group.
Borate esters of this type can be prepared in the same way as the
process described for Type I esters previously mentioned.
Type IV borate esters suitable for use in the fluids of this
invention include, for example: ##SPC3##
It is further noted that borate esters of Types II, III and IV will
include concomitant reaction products and other impurities of the
type as described above for Type I esters. Reference to these types
of borate esters in the specification and claims is intended to
include relatively pure borate ester as well as crude borate ester
which contains impurities and other by-products formed during
preparation as described above for Type I.
FORMAL COMPONENT
The formal portion of the hydraulic fluid composition of this
invention will generally comprise from about 2 to about 40 percent
by weight, based on the total weight of the hydraulic fluid, of one
or more bis(glycol ether) formals having the formula:
[R.sub.b O(R.sub.a O).sub.x ].sub.2 CH.sub.2 (V)
wherein R.sub.b is alkyl of one to six carbon atoms, preferably one
to four, R.sub.a is alkylene of two to four carbon atoms,
preferably two to three and x is an integer of 1 to 5, preferably 1
to 3. The R.sub.b and R.sub.a groups may be straight or branched
chained and it is also intended that the alkylene oxide group
(R.sub.a O) in the above formula (V) include mixtures of said
alkylene oxides.
Illustrative of the above type formals (V) are the following
compounds:
[CH.sub.3 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2
[ch.sub.3 o(c.sub.2 h.sub.4 o).sub.2 ].sub.2 ch.sub.2
[ch.sub.3 o(c.sub.2 h.sub.4 o).sub.3 ].sub.2 ch.sub.2
[c.sub.2 h.sub.5 o(c.sub.2 h.sub.4 o).sub.2 ].sub.2 ch.sub.2
[c.sub.4 h.sub.9 o(c.sub.2 h.sub.4 o)].sub.2 ch.sub.2
[c.sub.4 h.sub.9 o(c.sub.2 h.sub.4 o).sub.3 ].sub.2 ch.sub.2
[ch.sub.3 o(ch.sub.2 chch.sub.3 o)].sub.2 ch.sub.2
[ch.sub.3 o(ch.sub.2 chch.sub.3 o).sub.2 ].sub.2 ch.sub.2
[c.sub.2 h.sub.5 o(ch.sub.2 chch.sub.3 o).sub.2 ].sub.2
ch.sub.2
[ch.sub.3 o(c.sub.2 h.sub.4 o)(ch.sub.2 chch.sub.3 o)].sub.2
ch.sub.2
while any of the above formals defined by formula (V) may be used,
the following bis(glycol ether) formals are particularly
useful:
[CH.sub.3 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2
[ch.sub.3 o(c.sub.2 h.sub.4 o).sub.2 ].sub.2 ch.sub.2
[ch.sub.3 o(c.sub.2 h.sub.4 o).sub.3 ].sub.2 ch.sub.2
[c.sub.2 h.sub.5 o(c.sub.2 h.sub.4 o).sub.2 ].sub.2 ch.sub.2
[c.sub.4 h.sub.9 o(c.sub.2 h.sub.4 o)].sub.2 ch.sub.2
[c.sub.4 h.sub.9 o(c.sub.2 h.sub.4 o).sub.3 ].sub.2 ch.sub.2
the above formals may be prepared by reacting the appropriate
glycol with paraformaldehyde and removing the water of condensation
which forms. Preparative techniques are commonly known in the art,
e.g., British Pat. No. 506,613 June 1, 1939); Chemical Abstracts,
33, 9325 (1939) discloses a process for the preparation of
condensation products of aldehydes with polyhydric alcohols or
partial ethers thereof. Other known methods of preparation are
disclosed in Canadian Pat. No. 390,733 (Aug. 13, 1940); Chemical
Abstracts, 34, 6948 (1940), and in J.Am.Chem.Soc., "Formaldehyde
bis(.beta.-ethoxyethyl) and bis(.beta.-ethoxyethoxyethyl) acetal,"
by M. Sulzbacher, 72, 2795-6, (1950).
While the hydraulic fluid composition of this invention may contain
from about 2 to about 40 percent by weight, based on the total
weight of the hydraulic fluid, of the above formals (V), preferred
embodiments include about 2 to about 15 and more preferably from
about 2 to about 10 percent by weight.
The use of these formals enable the hydraulic fluids of this
invention to function over a wide range of climatic and operational
conditions particularly because of desirable temperature-viscosity
relationships which such hydraulic fluids possess.
DILUENTS
The diluent portion of the hydraulic fluid composition of this
invention generally will comprise one or more compounds selected
from the group consisting of (a) glycol monoethers or diethers (b)
glycols and polyglycols and (c) aliphatic saturated alcohols.
More particularly, the glycol monoethers or diethers have the
formula:
R[O--R"].sub.y OR' (VI)
wherein R is alkyl of from one to four carbon atoms, preferably one
to two, R' is hydrogen or alkyl of from one to four carbon atoms,
preferably one to two, R" is alkylene of two to four carbon atoms,
preferably two to three, and y is 2 to 4. The R, R' and R" groups
may be straight chained or branched and it is also intended that
the alkylene oxide groups (O--R") in the above formula (VI) include
mixtures of said alkylene oxides.
Illustrative of the diluents of this type (VI) are the following
compounds: diethylene glycol monomethyl ether, diethylene glycol
monoethyl ether, diethylene glycol monoisopropyl ether, diethylene
glycol monoisobutyl ether, triethylene glycol monomethyl ether,
triethylene glycol monoethyl ether, triethylene glycol mono-n-butyl
ether, tetraethylene glycol monomethyl ether, tetraethylene glycol
monethyl ether, dipropylene glycol monomethyl ether, dipropylene
glycol monoethyl ether, tripropylene glycol monomethyl ether,
tripropylene glycol monoethyl ether, tripropylene glycol
mono-n-butyl ether, tetrapropylene glycol monomethyl ether,
tetrapropylene glycol monoethyl ether, dibutylene glycol monomethyl
ether, dibutylene glycol monoethyl ether, tributylene glycol
monomethyl ether, tributylene glycol monoethyl ether, tributylene
glycol mono-n-propyl ether, tetrabutylene glycol monomethyl ether,
tetrabutylene glycol monoethyl ether, tetrabutylene glycol
mono-n-butyl ether and the corresponding diethers thereof. It is
further noted that the above diluents include the various isomers
of the respective compounds and mixtures thereof.
While any of the above glycol ethers defined by formula (VI) may be
used, the following glycol ethers are particularly useful:
diethylene glycol monomethyl ether, diethylene glycol monoethyl
ether, diethylene glycol monobutyl ether, triethylene glycol
monomethyl ether, triethylene glycol monoethyl ether, triethylene
glycol monobutyl ether, tetraethylene glycol monomethyl ether and
tetraethylene glycol monobutyl ether.
The glycol ethers are the most preferred diluent since their use
will result in a fluid having a desirably high boiling point with
good viscosity and water solubility properties. Most preferred of
the glycol ethers are the ethylene glycols.
The second group of useful diluents are the glycols and
polyglycols, including alkylene, polyalkylene and polyoxyalkylene
glycols, having a molecular weight of from about 60 to about 450
and preferably from about 100 to about 300. Illustrative of such
type diluents are the following compounds: ethylene glycol,
propylene glycol, hexylene glycol, diethylene glycol, dipropylene
glycol, triethylene glycol, tripropylene glycol, polyethylene
glycol and polypropylene glycol.
The use of the glycols and polyglycols as diluents is not as
desirable as the glycol ethers since their use may result in some
loss of fluidity at very low temperatures, however, they may be
used in conditions where the requirements are not as demanding.
The third type of useful diluents are aliphatic, saturated
monohydric alcohols containing from six to 13 carbon atoms,
preferably from eight to 10. Illustrative of such diluents are the
following alcohols: hexanol, octanol, isooctanol, decanol,
isodecanol, dodecanol, and tridecanol.
Since the use of the aliphatic alcohols in a high boiling hydraulic
fluid may result in some loss of water solubility, they are not as
desirable as the glycol ethers. However, they may be used in
conditions where the requirements are not as stringent.
The diluent portion of the hydraulic fluids of this invention
generally will comprise from 0 to about 78 percent by weight,
preferably from about 2 to about 70 and more preferably from about
6 to about 45 percent by weight, based on the total weight of the
hydraulic fluid composition.
While the above diluents, especially the glycol ethers, are
particularly preferred, other diluents may be used if the desired
properties and characteristics of the hydraulic fluid can be
attained. For example, certain diesters derived from organic
aliphatic acids and aliphatic alcohols might be usefully employed.
Examples of diesters which might be used include dibutyl adipate,
bis(methoxyethyl azelate, diisopropyl succinate, dipropylene glycol
diproprionate and triethylene glycol dibutyrate.
ADDITIVES
When desired, various additives may be added to the hydraulic
fluids of this invention to control or modify various chemical and
physical properties of the fluids. Among the various types of
additives which can be added to the hydraulic fluids of this
invention are included: inhibitors for pH and corrosion control,
antioxidants, rust inhibitors, viscosity index improvers, pour
point depressants, lubricating additives, antifoamants,
stabilizers, demulsifiers, dyes and odor suppressants. Generally,
the total amount of additives which may be incorporated into the
fluid composition will vary depending on the particular composition
and the desired properties. More particularly, the total amount of
additives will comprise from 0 to about 10 percent and preferably
from about 0.1 to about 8.0 percent by weight based on the total
weight of the hydraulic fluid composition.
For example, inhibitors for pH and corrosion control, such as
alkaline inhibitors as exemplified by the alkali metal borates, can
be employed in an amount sufficient to maintain alkaline conditions
in the fluid compositions, e.g., a pH value of from about 7.0 to
about 11.5. These inhibitors are generally added in an amount of
from 0 to about 8.0 percent by weight based on the total weight of
the hydraulic fluid composition and preferably from about 0.2 to
about 6.0 percent by weight on the same basis. Useful inhibitors
include alkali metal borates, such as sodium borate, potassium
tetraborate, etc.; sodium meta arsenite; alkali metal salts of
fatty acids, such as potassium oleate, the potassium soap of rosin
or tall oil; alkylene glycol condensates with alkali metal borates,
such as the ethylene glycol condensate of potassium tetraborate;
amines, for example, ethanolamine, methyl diethanolamine,
diethanolamine, isopropanolamines(mono, di and tri),
di(2-ethylhexyl) amine, di-N-butyl amine, monoamyl amine,
diamylamine, dioctylamine, salicylal monoethanolamine,
di-.beta.-naphthyl-p-phenylene diamine,
N,N'-disalicylidene-1,2-propanediamine, N,N"-disalicylal ethylene
diamine, dicyclohexylamine, and amine salts such as mono or dibutyl
ammonium borate; phosphites, such as triphenyl phosphite,
tri(tertamylphenyl) phosphite, diisopropyl phosphite, etc.;
mercaptobenzotriazole; morpholine compounds including alkyl
morpholines having from one to four carbon atoms in the alkyl group
such as N-ethyl morpholine, N-isopropyl morpholine, N-butyl
morpholine; N-phenyl morpholine, N-(2-aminoethyl) morpholine,
N-(2-hydroxyethyl) morpholine, etc.; phosphates, including the
alkali metal phosphates, dibutyl amine phosphates, the dialkyl acid
o-phosphates and amine salts thereof; triazoles including
benzotriazole, 1,2-naphthotriazole, 4-nitrobenzotriazole,
tolutriazole, aminobenzotriazoles such as 5-acylaminobenzotriazole,
and alkyl triazoles having one to 10 carbon atoms in the alkyl
group as exemplified by methyl triazole, ethyl triazole, n-propyl
triazole, tertiary butyl triazole, hexyl triazole, isodecyl
triazole, etc. Other useful corrosion inhibitors include adenine,
4-methylimidazole, 3,5-dimethyl pyrazole, 6-nitroidazole,
imidazole, benzimidazole, quanine, indazole, ammonium
dinonylnaphthaline sulfonate, dioleyl thiodipropionate,
ethylbenzoate, ethyl-p-aminobenzoate, cyclohexyl ammonium nitrite,
diisopropyl ammonium nitrite, butynediol, glycerin,
1,3,5-trimethyl-2,4,6-tris (3,5-di-tert. butyl-4-hydroxybenzoyl),
4,4'-methylene bis(2,6-di-tert. butylphenyl),
4-hydroxymethyl-2,6-di-tert. butylphenyl, 4,4'-methylene
bis(4-methyl-6-tert. butylphenyl), salicylal-o-aminophenol,
2,6-di-tert. butyl-2-dimethylamino-p-cresol, 4,4'-thio bis(6-tert.
butyl-o-cresol), Mixtures of the above-mentioned inhibitors can be
employed if desired.
While any of the above-mentioned inhibitors may be used for pH and
corrosion control, the following inhibitors are particularly
useful: glycerin, butynediol, diethanolamine, methyl
diethanolamine, mixed isopropanolamines, diisopropanolamine and
triisopropanolamine.
An antioxidant may be used as an additive in the hydraulic fluid
compositions of this invention if desired. Generally the amount of
antioxidant used will vary from 0 to about 2 percent and preferably
will be from about 0.001 to about 1.0 percent by weight based on
the total weight of the fluid composition. Typical antioxidants
include phenolic compounds, such as 2,2-di-(4-hydroxyphenol)
propane, phenothiazine, phenothiazine carboxylic acid esters,
N-alkyl or N-arylphenothiazines, such as N-ethyl phenothiazine,
N-phenyl phenothiazine, etc.; polymerized
trimethyldihydroquinoline; amines, such as
phenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, dioctyl
diphenylamine, N,N-di-.beta.-naphthyl-p-phenylene diamine,
p-isopropoxy diphenylamine, N,N-dibutyl-p-phenylene diamine,
diphenyl-p-phenylene diamine,
N,N'-bis(1,4-dimethylpentyl)-p-phenylene diamine,
N,N'-diisopropyl-p-phenylene diamine, p-hydroxydiphenylamine, etc.;
hindered phenols such as dibutyl cresol, 2,6-dimethyl-p-cresol,
butylated 2,2-di-(4-hydroxyphenyl) propane, n-butylated
aminophenol, butylated hydroxyanisoles, such as
2,6-dibutyl-p-hydroxyanisole; anthraquinone,
dihydroxyanthraquinone, hydroquinone,
2,5-di-tertiarybutylhydroquinone, 2-tertiary butylhydroquinone,
quinoline, p-hydroxydiphenylamine, phenyl benzoate, 2,6-dimethyl
p-cresol, p-hydroxyanisole, nordihydroquaiaretic acid,
pyrocatechol, styrenated phenol, polyalkyl polyphenols, sodium
nitrite, etc. Mixtures of the above-mentioned antioxidants can be
employed, if desired. It should be emphasized that with a variety
of the fluids of this invention, which are suitable for a wide
range of industrial application, a separate antioxidant is not
required.
While any of the above-mentioned antioxidants may be used, the
following antioxidants are particularly preferred: sodium nitrite
and dioctyl diphenylamine.
The above-noted inhibitors and additives are merely exemplary and
are not intended as an exclusive listing of the many well-known
materials which can be added to fluid compositions to obtain
various desired properties. Numerous additives useful in hydraulic
fluids are disclosed in Introduction to Hydraulic Fluids by Roger
E. Hatton, Reinhold Publishing Corp., (1962).
Formulation of the novel hydraulic fluids of this invention is
accomplished by blending the components to a homogeneous stage in a
mixing vessel. The preferable blending temperature is from about
50.degree.-125.degree. F. It is preferable to warm the solution
during preparation to facilitate dissolution. The blending of the
compounds is conveniently conducted at atmospheric pressure in the
absence of moisture.
In general, any suitable method can be used in preparing the liquid
compositions of this invention. The components can be added
together or one at a time, in any desired sequence. It is
preferable, however, to add the antioxidant and alkaline inhibitor
as a solution in the glycol ether component. All components are
mixed until a single phase composition is obtained.
The following examples which illustrate various embodiments of this
invention are to be considered not limitative.
EXAMPLE 1
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 14.35 [CH.sub.3 O(C.sub.2
H.sub.4 O).sub.2 ].sub.2 CH.sub.2 10.00 Mixed isopropanolamine
(10-15% mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol
0.50 Dioctyl diphenylamine (Van Lube 81 produced by R. T.
Vanderbilt Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00
This fluid composition was tested according to the procedures set
forth in Society of Automotive Engineers Standard J1703. The data
relating to these tests, which illustrate the outstanding
properties of this fluid is shown in Table 1.
The reflux boiling point (dry) of the above fluid was measured and
found to be 532.degree. F. at atmospheric pressure. To test the
water insensitivity of the fluid composition, a sample of 100 parts
by volume of the fluid plus 3.5 parts by volume of water was
prepared and it was found to have a reflux boiling point (wet) at
atmospheric pressure of 367.degree. F. indicating the high degree
of water insensitivity. ##SPC4##
EXAMPLE 2
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
[C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.2 O].sub.3 --B 14.35
[CH.sub.3 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2 CH.sub.2 10.00 Mixed
isopropanolamines (10-15% mono, 40-50% di, 40-50% tri) 3.00
Glycerin 2.00 Butynediol 0.50 Dioctyl diphenylamine (Van Lube 81
produced by R. T. Vanderbilt Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 515.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 365.degree. F.
Viscosity at -40.degree. F. 1852 cs.
EXAMPLE 3
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 19.35 [CH.sub.3 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2 5.00 Mixed isopropanolamines (10-15%
mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol 0.50
Dioctyl diphenylamine (Van Lube 81 produced by R. T. Vanderbilt
Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 481.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 339.degree. F.
Viscosity at -40.degree. F. 1,515 cs.
EXAMPLE 4
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 4.35 [CH.sub.3 O(C.sub.2 H.sub.4
O)].sub.2 CH.sub.2 20.00 Mixed isopropanolamines (10-15% mono,
40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol 0.50 Dioctyl
diphenylamine (Van Lube 81 produced by R. T. Vanderbilt Co.) 0.10
Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 453.degree.F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 333.degree.F.
Viscosity at -40.degree.F. 720 cs.
EXAMPLE 5
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 19.35 [CH.sub.3 O(C.sub.2
H.sub.4 O).sub.2 ].sub.2 CH.sub.2 5.00 Mixed isopropanolamines
(10-15% mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol
0.50 Dioctyl diphenylamine (Van Lube 81 produced by R. T.
Vanderbilt Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 505.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 345.degree. F.
Viscosity at -40.degree. F. 1,865 cs.
EXAMPLE 6
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 4.35 [CH.sub.3 O(C.sub.2 H.sub.4
O).sub.2 ].sub.2 CH.sub.2 20.00 Mixed isopropanolamines (10-15%
mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol 0.50
Dioctyl diphenylamine (Van Lube 81 produced by R. T. Vanderbilt
Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 523.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 354.degree. F.
Viscosity at -40.degree. F. 1,415 cs.
EXAMPLE 7
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 19.35 [C.sub.4 H.sub.9 O(C.sub.2
H.sub.4 O)].sub.2 CH.sub.2 5.00 Mixed isopropanolamines (10-15%
mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol 0.50
Dioctyl diphenylamine (Van Lube 81 produced by R. T. Vanderbilt
Co.) 0.10 Sodium nitrite 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 502.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 343.degree. F.
Viscosity at -40.degree. F. 1,771 cs.
EXAMPLE 8
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
51.80 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub. 4 O].sub.3 --B 18.20
Triethylene glycol monoethyl ether 19.35 [CH.sub.3 O(C.sub.2
H.sub.4 O).sub.3 ].sub.2 CH.sub.2 5.00 Mixed isopropanolamines
(10-15% mono, 40-50% di, 40-50% tri) 3.00 Glycerin 2.00 Butynediol
0.50 Dioctyl diphenylamine (Van Lube 81 produced by R. T.
Vanderbilt Co.) 0.10 Sodium nitrate 0.05
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 504.degree. F. Reflux
boiling point (wet) (3.5 ml. water +100 ml. fluid) 343.degree. F.
Viscosity at -40.degree. F. 2,083 cs.
EXAMPLE 9
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
[CH.sub.3 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B 20.00 Triethylene
glycol monomethyl ether 58.00 [C.sub.2 H.sub.5 O(C.sub.2 H.sub.4
O).sub.2 ].sub.2 CH.sub.2 15.00 Polyethylene glycol (M.W. 300 )
5.00 Diethanolamine 2.00
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 490.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 308.degree. F.
Viscosity at -40.degree. F. 522.3 cs.
EXAMPLE 10
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
[C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.2 O].sub.3 --B 25.00
Tetraethylene glycol monoethyl ether 15.00 Triethylene glycol
monoethyl ether 39.00 [C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3
].sub.2 CH.sub.2 20.00 Monoethanolamine 1.00
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 436.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 304.degree. F.
Viscosity at -40.degree. F. 607.1 cs.
EXAMPLE 11
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
[CH.sub.3 (OC.sub.2 H.sub.4).sub.3 (OCH.sub.2 CHCH.sub.3) (OC.sub.2
H.sub.4)O].sub.3 --B 30.00 Triethylene glycol monomethyl ether
57.00 [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2 CH.sub.2 10.00
Triisopropanolamine 3.00
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 504.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 308.degree. F.
Viscosity at -40.degree. F. 516.3 cs.
EXAMPLE 12
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
[C.sub.4 H.sub.9 O(50% C.sub.2 H.sub.4 0 + 50% CH.sub.2 CHCH.sub.3
O).sub.4 ].sub.3 B 35.00 (Prepared using Union Carbide glycols Veon
50-HB55) Triethylene glycol monoethyl ether 22.00 Polyethylene
glycol (M.W. 300) 10.00 [CH.sub.3 O(C.sub.2 H.sub.4 O).sub.3
].sub.2 CH.sub.2 30.00 Diisopropanolamine 2.5 Dioctyl diphenylamine
(Van Lube 81 produced by R. T. Vanderbilt Co.) 0.5
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 542.degree. F. Reflux
boiling point (wet) (3.5 ml. water + 100 ml. fluid) 315.degree. F.
Viscosity at -40.degree. F. 848.8 cs.
EXAMPLE 13
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [CH.sub.3 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B 30.0
Tetraethylene glycol monomethyl ether 22.0 Triethylene glycol
monoethyl ether 42.0 [CH.sub.3 O(C.sub.2 H.sub.4 O)].sub.2 CH.sub.2
5.0 Monoethanolamine 1.0
__________________________________________________________________________
100.00 Properties: Reflux boiling point (dry) 467.degree. F. Reflux
boiling point (wet) 321.degree. F. (3.5 ml. water + 100 ml. fluid)
Viscosity at -40.degree. F. 660 cs
EXAMPLE 14
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate Ester [CH.sub.3 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B 20.0
[C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.2 O].sub.3 -- B 15.0
Triethylene glycol monomethyl ether 20.0 Triethylene glycol
monobutyl ether 17.0 Polyethylene glycol (M.W. 300) 15.0 [C.sub.2
H.sub.5 O(C.sub.2 H.sub.4 O).sub.2 ].sub.2 CH.sub.2 10.0
Monoisopropanolamine 3.0
__________________________________________________________________________
100.0 Properties Reflux boiling point (dry) 445.degree. F. Reflux
boiling point (wet) 321.degree. F. (3.5 ml. water + 100 ml. fluid)
Viscosity at - 40.degree. F. 2,437 cs
EXAMPLE 15
A hydraulic fluid was prepared having the following
composition:
Percent by Weight
__________________________________________________________________________
Borate ester [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.3 O].sub.3 --B
29.6 [C.sub.2 H.sub.5 (OC.sub.2 H.sub.4).sub.4 O].sub.3 --B 10.4
Tetraethylene glycol monoethyl ether 10.0 Triethylene glycol
monoethyl ether 41.0 [C.sub.4 H.sub.3 O(C.sub.2 H.sub.4 O)].sub.2
CH.sub.2 5.0 Methyl diethanolamine 4.0
__________________________________________________________________________
100.0 Properties: Reflux boiling point (dry) 487.degree. F. Reflux
boiling point (wet) 319.degree. F. (3.5 ml. water + 100 ml. fluid)
319.degree. F. Viscosity at -40.degree. F. 901 cs
* * * * *