Note: Descriptions are shown in the official language in which they were submitted.
W092/02~6 1 PCT/US91/o~
D~SCRI~TI~?N 2 0 ~ 7 8 ~ 7
~`
. `. . .
; AZEOTROPE-LIKE COMPOSITIONS OF
DICHLORO-l FLUOROETHANE, E~HANOL: AND NITROMETHANE
.'~'~ , , .
Field of the Invention -
This invention relates to azeotrope-like mi~tures
; of l,l-dichloro-l fluoroethane; ethanol; and
~; nitromethane. These mi~tures are useful in a variety of
;; 10 vapor degreasing, cold cleaning and solvent cleaning
applications including defluxing. ~
' . ' , ' - ,:
~RO~ ~REFERENCE TO RELATED APPLICATIQNS
, " .
Co-pending, commonly assigned patent application
Serial No. 345,732, filed May 1, 1989, discloses
azeotrope-lik~ mi~tures of l,l-dichloro-l-fluoroethane;
I dichlorotrifluoroethane; nitromethane; and methanol or
ethanol.
, 20
Co-pending, commonly assigned patent application
Serial No. 417,134, filed October 4, 1989, discloses
azeotrope-like mi~tures of l,l-dichloro-l-fluoroethane;
dichlorotrifluoroethane; and nitromethane.
2~
BACXGROUND OF THE INV~NTION
:.",
~` Vapor degreasing and solvent cleaning with
` fluorocarbon based solvents have found widespread use in
:; 30 industry for the degreasing and otherwise cleaning of
solid surfaces, especially intricate parts and difficult
to remove soils.
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W~92/02 ~ ~ PCT/US91/0~2_
In its simplest form, vapor degreasing or solvent
cleaning consists of e~posing a room temperature object to
be cleaned to the vapors of a boiling solvent. Vapors
condensing on the object provide clean distilled solvent
to wash away grease or other contamination. Final
evaporation of solvent from the object leaves behind no
~ residue as would be the case where the object is simply
; washed in liquid solvent.
For difficult to remove soils where elevated
temperature is necessary to improve the cleaning action of -
. the solventi or for large volume assembly line operations
where the cleaning of metal parts and assemblies must be
done efficiently and quickly, the conventional operation
-l5 of a vapor degreaser consists of immersing the part to be
cleaned in a sump of boilin~ solvent which removes the
bulk of the soil, thereafter immersing the part in a sump
containing freshly distilled solvent near room
~`temperature, and finally e~posing the part to solvent
`~;20 vapors over the boiling sump which condense on the cleaned
part. In addition, the part can also be sprayed with
distilled solvent before final r nsing.
Vapor degreasers suitable in the above-described
- operations are well known in the art. For e2ample,
Sherliker et al. in U.S. Patent 3,085,9l8 disclose such
suitable vapor degreasers comprising a boiling sump, a
clean sump, a water separator, and other ancillary
equipment.
Cold cleaning is another application where a number
of solvents are used. In most cold cleaning applications,
the soiled part is either immersed in the fluid or wiped
with rags or similar objects soaked in solvents and
allowed to air dry.
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W092/02~6 ~ 0 8 ~ 7 PCT/~s91/~2
- Fluorocarbon solvents, such as
trichlorotrifluoroethane, have attained widespread use in
recent years as effective, nontoxic, and nonflammable
agents useful in degreasing applications and other solvent
cleaning applications. Trichlorotrifluoroethane has been
found to have satisfactory solvent power for greases,
oils, wa~es and the like. It has therefore found
widespread use for cleaning electric motors, compressors,
heavy metal parts, delicate precision metal parts, printed
circuit boards, gyroscopes, guidance systems, aerospace
and missile hardware, aluminum parts and the like.
The art has looked towards azeotrope or
azeotrope-like compositions including the desired
- lS fluorocarbon components such as trichlorotrifluoroethane
which include components which contribute additionally
desired characteristics, such as polar functionality,
increased solvency power, and stabilizers. Azeotropic or
azeotrope-lik 3 compositions are desired because they do
not fractionate upon boiling. This behavior is desirable
; because in the previously described vapor degreasing
equipment with which these solvents are employed,
redistilled material is generated for final
rinse-cleaning. Thus, the vapor degreasing system acts as
a still. Unless the solvent composition eshibits a
constant boiling point, i.e., is azeotrope-like,
fractionation will occur and undesirable solvent
; distribution may act to upset the cleaning and safety of
processi~g. Preerential evaporation of the more volatile
components of the solvent mi~tures, which would be ~he
case if they were not azeotrope-like, would result in
mi~tures with changed compositions which may have less
desirable properties, such as lower solvency towards
soils, less inertness towards metal, plastic or elastomer
:: jS components, and increased flammability and toYiClty.
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wc~s2~2666 ~ ,`,1 Pcr/ussl/04~47_
The art is continually seeking new fluorocarbon
hased azeotrope-like mi~tures which offer alternatives for
new and special applications for vapor degreasing and
other cleaning applications. Currently, of particular
interest, are fluorocarbon based azeotrope-like mi~tures
which are considered to be stratospherically safe
substitutes for presently used fully halogenated
chlorofluorocarbons. The latter are suspected of causing
environmental problems in connection with the earth's
protective ozone layer. Mathematical models have
substantiated that hydrochlorofluorocarbons, such as
l,l-dichloro-l-fluoroethane ~HCFr-141b), will not
~-~ adversely affect atmospheric chemistry, being negligible
contributors to ozone depletion and to green-house global
warming in comparison to the fully halogenated species.
HCFC-141b is known to be useful as a solvent. HCFC-141b
~; has a boiling point of about 32C.
.
The use of the aerosol packaging concept has long
been found to be a convenient and cost effective means of
dispensing solvents. Aerosol products utilize a
propellant gas or mi2ture of propellant gases, preferably
in a liquified gas rather than a compressed gas state, to
generate sufficient pressure to e~pel the active
ingredients, i.e. product concentrates such as solvents,
from the container upon opening of the aerosol valve. The
propellants may be in direct contact with the solvent, as
in most conventional aerosol systems, or may be isolated
from the solvent, as in barrier-type aerosol systems.
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2~8~7
WO 92/0266~ - 5 - PCI/US91/0q842
- Csrnrronly assigned U.S. Patent 4,836,947 discloses
azeotrope-like mi~tures of l,l-dichloro-l-fluoroethane and
ethanol. Commonly assigned U.S. Patent 4,842,764
discloses azeotrope-like mi~tures of
5 l,l-dichloro-l-fluoroethane and methanol. Commonly
assigned U.S. Patent 4,816,174 discloses axeotrope-like
mi~tures of l,l-dichloro-l-fluoroethane, methanol, and
nitromethane. Commonly assigned U.S. Patent 4,863,630
discloses azeotrope-like mixtures of
~` 10 l,l-dichloro-l-fluoroethane; dichlorotrifluoroethane; and
ethanol.
Kokai Patent Publication 103,686, published April
20, 1989, discloses an azeotropic mi:~ture of 55 to 80
lS weight percent dichlorotrifluoroethane and 20 to 45 weight
percent 1,1-dichloro-1-fluoroethane. Kokai Patent
Publication 136,981, published May 30, 1989, discloses a
degreasing cleanin~ agent of 25 weight percent ethanol and
75 weight percent of an azeotropic composition of 25
2 weight percent 1,1-dichloro~l-fluoroethane and 50 weight
percent l,l-dichloro-2,2,2-trifluoroethane.
Kokai Patent Publication 136,982, published May 30,
1989, discloses a buff-grinding cleaning agent of 25
weight percent ethanol and 75 weight percent of an
azeotropic composition of 25 weight percent
l,l-dichloro-l-fluoroethane and 50 weight percent
1,1-dichloro-2,2,2-trifluoroethane. Kokai Patent
Publication 137,253, published May 30, lsas! discloses a
resist developing agent of 25 weight percent ethanol and
75 weight percent of an azeotropic composition of 25
weight percent l,l-dichloro-l-fluoroethane and 50 weight
percent l,l-dichloro-2,2,2-trifluoroethane.
'
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W092/02~6 ~a~ 6 - PCT/US91/0~2_
Kokai Patent Publication 137,259, published May 30,
1989, discloses a resist separating agent of 15 weight
~: percent ethanol, 10 weight percent alkyl benzene sulfonic
acid, and 75 weight percent of an azeotropic composition
: 5 o~ 2S weight percent 1,1-dichloro-1-1uoroethane and 50
weight percent 1,1-dichloro-2,2,2-tr;fluoroethane. Kokai
Patent Publication 138,300, published May 31, 1989,
: discloses a flu~ cleaning agent of 25 weight percent
methanol and 75 weight percent of an azeotropic
composition of 25 weight percent
dichloro-l-fluoroethane and 50 weight percent
1,1-dichloro-2,2,2-trifluoroethane.
.:
Kokai Patent Publication 139,104, published May 31,
1989, discloses a solvent of 5 weight percent
. trichloroethylene, 20 weight percent ethanol, and 75
: weight percent of an azeotropic composition of 25 weight
percent l,l-dichloro-l fluoroethane and 75 weight percent
1,1-dichloro-2,2,2-trifluoroethane. Kokai Patent
Publication 139,~61, published June 1, 1989, discloses a
. dry-cleaning agent of 25 weight percent ethanol and 75
; weight percent of an azeotropic composition of 25 weight
percent l,l-dichloro-l-fluoroethane and 75 weight percent
: 1,1-dichloro-2,2,2-tri~luoroethane.
It is an object of this invention to provide novel
:;~ azeotrope-like compositions bssed on ~CFC-141b which are
liguid at room temperature, which will not ractionate
~ substantially under the process of distillation or
; 30 evaporation, and which are useful as solvents for use in
vapor degreasing and other solvent cleaning applications
- . including deflu~ing applications and dry cleaning.
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W~2/02~6 _ 7 ~ ~ 7 ~ ~ ~7CT/US91/04~ :
:-.
Another object of the invention is to provide novel
environmentally acceptable solvents for use in the
aforementioned applications~
Other objects and advantages of the invention will
become apparent from the following description.
~ESCRIP~ION OF THE INVENTI~N
'~' ' '
In accordance with the invention, novel mi~tures
have been discovered comprising
dichloro-l-fluoroethane; ethanol; and nitromethane.
Also, novel azeotrope-like or constant-boili~g
compositions have been discovered comprising
l,1-dichloro-1-fluoroethane; ethanol; and nitromethane.
~-~ Preferably, the novel azeotrope-like compositions
comprise effective amounts of l,l-dichloro-l-fluoroethane;
ethanol; and nitromethane. The term ~effective amounts~
as used herein means the arnount of each component which
upon combination with the other component, results in the - -
;~ formation of the present a:zeotrope-like composition.
.. . ...
Preferably, novel azeotrope-like compositions
~ 25 comprise l,l-dichioro-l-fluoroethane; ethanol; and
,'~ nitromethane which boil at about 32.3C at 760 mm Hg (101
- kPa).
.,. :
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., 30
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~6 ~ r 8 _ PCT/US91/04~2_
Novel azeotrope-like compositions also preferably
comprise from about 95.5 to about 99.49 weight percent of
dichloro-l-fluoroethane; from about 0.5 to about 3.5
weight percent of ethanol; and from about 0.01 to about .'
1.0 weight pe_cent of nitromethane which boil at about
32.8C at 760 mm Hg (101 kPa), and more preferably, which
boil at about 32.8C ~ about 0.5C at 760 mm Hg (101 kPa).
..
More preferably, the azeotrope-like compositions of
10. the invention comprise from about 96.1 to about 9~.05
:; weight percent of l,l-dichloro-1-fluoroethane; from about
' . 0.9 to about 3.0 weight percent of ethanol; and from about
: 0.05 to about 0.9 weight percent of nitromethane.
15 Most preferably, the azeotrope-like compositions of
-~ the invention comprise rom about 97.1 to about 98.75
weight percent of 1,1-dichloro-1-fluoroethane; from about
1.2 to about 2.0 weight percent of ethanol; and from about
- ' 0.05 to about 0.9 weight percent of nitromethane.
': 20
Although it is not be:Lieved that a true azeotropic
system is formed with l,1-dichloro-1-fluoroethane,
ethanol, and nitromethane, the term ~azeotrope-like" is
' used herein for the mi~tures of the invention because in
the claimed proportions, the compositions of
l,l-dichloro-l-fluoroethane, ethanol, and nitromethane are
constant-boiling or essentially constant-boiling and for
some reason, which is not fully understood, remain or hang
together in a vapor degreaser.
All compositions within the indicated ranges, as
well as certain compositions outside the indicated ranges,
are azeotrope-like, as defined more particularly below.
.
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~W092/02~6 - 9 -2 ~ ~ 7 3 d~/USgl/04&4~
The precise azeotrope compositions have not been
;determined but have be~n ascertained to ~e within the
above ranges. Regardless of where the true azeotropes
lie, all compositions with the indicated ranges, as well
as certain compositions outside the indicated ranges, are
azeotrope-like, as defined more particularly below.
It has been found that these azeotrope-like
compositions are on the whole nonflammable liquids, i.e.
10 e~hibit no flash point when tested by the Tag Open Cup -
test method - ASTM D 1310-86.
From ~undamental principles, the thermodynamic
state of a fluid is defined by four variables: pressure,
temperature, liquid composition and vapor composition, or
P-T-X-Y, respectively. An azeotrope is a unique
.characteristic of a system of two or more components where
X and Y are equal at the stated P and T. In practice,
this means that the components of a mi~ture cannot be
~20 s~parated during distillation, and therefore are useful in
: vapor phase solvent cleaning as described above.
' . .~ .
For the purpose of this discussion, azeotrope-like
composition is intended to mean that the composition
behaves like an azeotrope, i.e. has constant-boiling
^ ; characteristics or a tendency not to fractionate upon
.
boiling or evaporation. Thus, in such compositions, the
composition of the vapor formed during boiling or
evaporation is identical or substantially identical to the
;~,,",30 original liquid composition. Hence, during boiling or
evaporation, the liquid composition, if it changes at all,
changes only to a minimal or negligible e~tent. This is
to be contrasted with non-azeotrope-like compositions in
which during boiling or eYaporation, the liquid
composition changes to a substan~ial degree.
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~ W092/02666 ~ b~ - lo- PCT/US91/04~'
Thus, one way to determine whether a candidate
mi~ture is "azeotrope-like" within the meaning of this
invention, is to distill a sample thereof under conditions
(i.e. resolution number of plates) which would be
e~pected to separate the misture into its separate
-components. If the mi~ture is non-azeotrope-like, the
mixture will Cractionate, i.e. separate into its various
components with the lowest boiling component distilling
off first, and so on. If the mi~ture is azeotrope-like,
; lO some finite amount of a first distillation cut will be
obtained which contains all of the misture components and
which is constant-boiling or behaves as a single
substance. This phenomenon cannot occur if the mi~ture is
not azeotrope-like, i.e. it does not behave like an
azeotrope. Of course, upon distillation of an
azeotrope-like composition such as in a vapor degreaser,
the true azeotrope will form and tend to concentrate.
.
It follows from the above that another
` 20 characteristic of azeotrope--like compositions is that
there is a range of compositions containing the same
components in varyinq proportions which are azeotrope-like
- or constant-boiling. All such compositions are intended
to be covered by the term azeotrope-like or
constant-boiling as used herein. As an esample, it is
well known that at differing pressures, the composition of
a given azeotrope-like composition will vary at least
slightly as does the boiling point of the composition.
Thus, an azeotrope-like composition of A and B represents
a unique type of relationship buc with a variable
composition depending on temperature and~or pressure.
With l,l-dichloro-l-fluoroethane; ethanol; and
nitromethane, the mi~tures boil within + about 0.5C (at
about 760 mm Hg (lOl kPa)) of the 32.8C boiling point.
As is readily understood by persons skilled in the art,
the boiling point of the azeotrope-like composition will
vary with the pressure.
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w092/02~6 ~ 7 PCT/US91/04~
The azeotrope-like compositions of the invention
are useful as solvents in a variety of vapor degreasing,
cold cleaning and solvent cleaning applicati~ns including
defluxing.
In one process embodiment of the invention, the
azeotrope-like compositions of the invention may be used
to clean solid surfaces by treating said surfaces with
said compositions in any manner well known to the art such
as by dipping or spraying or use of conventional
degreasing apparatus.
.
When the present azeotrope-like compositions are
used to clean solid surfaces by spraying the surfaces with
the compositions, preferably, the azeotrope-like
- compositions are sprayed onto the surfaces by using a
propellant. Preferably, the propellant is selected from
~; the group consisting of hydrocarbons, chlorofluorocarbons,
hydrochlorofluorocarbon, hydrofluorocarbon, dimethyl
ether, carbon dio~ide, nitrogen, nitrous o~ide, methylene
o~ide, air, and mi~tures thereof.
; ~ .;
Useful hydrocarbon propellants include isobutane,
butane, propane, and mi~tures thereof; commercially
available isobutane, butane, and propane may be used in
the present inYention. Useful chlorofluorocarbon
propellants include trichlorofluoromethane (known in the
art as CFC-ll), dichlorodifluoromethane (known in the art
as CFC-12), 1,1,2-trichloro-1,2,2-trifluoroethane ~known
in the art as CFC-113), and
1,2-dichloro-1,1,2,2-tetrafluoroethane (known in the art
as CFC-114); commercially available CFC-ll, CFC-12,
CFC-113, and CFC-114 may be used in the present invention.
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WO9~/0~ 12 - PCT/~S91/~ ~2
Useful hydrochlorofluorocarbon propellants include
dichlorofluoromethane (known in the art as HCFC-21),
chlorodifluoromethane (known in the art as HCFC-22),
- l-chloro-1,2,2,2-tetrafluoroethane (known in the art as
HCFC-124), 1,1-dichloro-2,2-difluoroethane (known in the
art as HCFC-132a), 1 chloro-2,2,2-trifluoroethane (known
in the art as HCFC-133), and l-chloro-l,l-difluoroethane
(known in the art as HCFC-142b); commercially available
HCFC-21, HCFC-22, and HCFC-142b may be used in the present
invention. HCFC-124 may be prepared by a known process
such as that taught by U.S. Patent 4,843,181 and HCFC-133
may be prepared by a known process such as that taught by
U.S. Patent 3,003,003.
Useful hydrofluorocarbon propellants include
~i. 15
trifluoromethane (known in the art as HFC-23),
1,1,1,2-tetrafluoroethane (known in the art as HFC-134a~,
and l,1-difluoroethane (known in the art as HFC-152a);
commercially available HFC-23 and HFC-152a may be used in
the present invention. Until HFC-134a becomes availabls
in commercial quantities, HFC-134a may be made by a known
method such as that disclosed by U.S. Patent 4,851,595.
More preferred propellants i.nclude
hydrochlorofluorocarbons, hydrofluorocarbons, and mi~tures
thereof. The most preferrecl propellants include
chlorodifluoromethane and 1,1~1,2-tetrafluoroethane.
.~ .
The l,l-dichloro-l-fluoroethane; ethanol; and
nitromethane components of the novel solvent
azeotrope-like compositions of the invention are known
materials. Preferably, the materials should be used in
sufficiently high purity so as to avoid the introduction
of adverse influences upon the desired properties or
constant-boiling properties of the system.
~.
W092/02~6 - 13 - PCT/VSg1/0~2
2~87~7
It should be understood that the present
compositions may include additional components so as to
form new azeotrope-like or constant-boiling compositions.
Any such compositions are considered to be within the
scope of the present invention as long as the compositions
- are constant-boiling or essentially constant-boiling and
~ contain all of th~ essential components described herein.
. .
The present invention is more fully illustrated by
the following non-limiting Esamples.
'': '
EXAMPLE 1
., ,
To illustrate the constan -boiling nature of the
mixtures of this invention under conditions of actual use
in a vapor phlse degreasing operation, a vapor phase
degreasing machine was charged with a preferred mi~ture in
accordance with the invention, comprising about 98.5
weight percent of HCFC-141b, about 1.2 weight percent of
ethanol, and about 0.3 weight percent of nitromethane.
The mi~ture was evaluated for its constant boiling or
non-segregating characteristics. The ~apor phase
degreasing machine utilized was a small water-cooled,
three-sump vapor phase degreaser which represents a type
of system configuration comparable to machine types in the :-
2~field today which would present the most rigorous test of
solvent segregating behavior. Specifically, the degreaser
employed to demonstrate the invention contained two
overflowing rinse-sumps and a boil-sump. The boil-sump
and the still were electrically heated, and each contained
a low-level shut-off switch. Solvent vapors in both the
degreaser and the still were condensed on water-cooled
stainless-steel coils. The still was fed by gravity from
the boil sump. Condensate from the still was returned to
the ~irst rinse-sump, also by gravity. The capacity of
the unit was approximately 1.5 gallons. This degreaser
was very similar to degreasers which are commonly used in
commercial establishments.
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W092/02~ 14 ~ PCT/US91/o~?
The solvent charge was brought to ref lu2 and the
compositions in the condensate sump containing the clear
condensate from the still, the work sump containing the
overflow from the condensate sump, the boil sump where the
overflow from the work sump is brought to the mi~ture
boiling points, and the still were determined with a
Perkin Elmer Sigma 3 gas chromatograph. The temperature
of the liquid in all the sumps was monitored with
thermocouple temperature sensing devices accurate to +
0.2C. Reflu~ing was continued for about 30 hours and
boil and condensate sump compositions were monitored
throushout this time. A mi~ture was considered
constant-boiling or non-segregating if the ma~imum
concentration difference between sumps for any mi~ture
component was + 2 sigma around the mean value. Sigma is a
standard deviation unit and it is our esperience from many
observations of vapor degreaser performance that
commercial "aæeotrope-like~ vapor phase degreasing
solvents e~hibit at least a + 2 sigma variation in
composition with time and yet produce very satisfactory
non-segregating cleaning behavior.
If the mi~ture were not azeotrope-like, the high
boiling components would very quickly concentrate in the
still and be depleted in the rinse sump. This did not
happen. Also. the concentration of each component in the
sumps stayed well within + 2 sigma. These results
indicate that the compositions of this invention will not
segregate in any type of large-scale commercial vapor
degreasers, thereby avoiding potential safety,
performance, and handling problems. The pre erred
composition tested was also found to not have a flash
point according to recommended procedure ASTM D 1310-86
~Tag Open Cup). The compositions in the sumps are shown
in Table I below.
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W092/02666 - 15 - PCT/US91/04~2
~873~7
TABLE I
.
~ Degreaser Composition Stability Study
.
5 ond~nsate SumP
Initial
. ~om~osition 24 hour 48 hour
HCFC-141b 98.5 98.5 98.6
Ethanol 1.2 1.3 1.3
Nitromethane 0.3 0.1 0.1
-~ Temperature (C) - 23.2 22.5
: Barometric Pressure
-~' (mm of Hg) - 748.8. 745.5
~ kPa) (100) (99)
.. ~, .
.
Boil SumP :
:. Initial
. Com~ositiQn 24 hQur 48 hQur.
: HCFC-141b 98.5 98.2 98.1 .
20 Ethanol 1.2 o.g o.g
Nitromethane 0.3 0O8 0.9
;~ Temperature (C) - 32.3 32.4~ ~
Barometric Pressure :
~:~; (mm of Hg) - 748.8 745.5
(100) (99)
Temperature (C) 32.8 32.9
Corrected to
. 760 mm Hg Pressure
(101 kPa)
, .
EXAMP~E 2
~ ~ E~ample 1 was repeated e~cept that the vapor phase
: degreasing machine was charged with another preferred
mi~ture in accordance with the invention, comprising about
97.7 weight percent of HCFC-141b, about 2.0 weight percent
o ethanol, and about 0.3 ~eight percent of nitromethane.
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; W~92/02~ ~ 16 - PCT/US9l/04~7
If the mixture were not azeotrope-like, the high
- boiling components would very ~u-ckly concentrate in the
still and be depleted in the rinse sump. This did not
happen. Also, the concentration of each component in the
sumps stayed well within + 2 sigma. These results
indicate that the compositions of this invention will not
segregate in any type of large-scale commercial vapor
degreasers, thereby avoiding potential safety,
performance, and handling problems. The preferred
composition tested was also found to not have a flash
point according to recommended procedure ASTM D 1310-86
(Tag Open Cup). The compositions in the sumps are shown
in Table II below.
~ABLE II
Degreaser Composition Stability Study
Condensat~ Sump
Initial
Composition 24 hour 48 hour
HCFC-141b 97.7 98.098.0
-~ Ethanol 2.0 1.81.8
Nitrom~thane 0.3 0.10.1
25 Temperature (C) - 21.321.3
Barometric Pressure
(mm of Hg)(kPa) - 746.4753.0
gg)(100)
~oil S~
Initial
~omposition 24 hour 48 hour
~CFC-141b 97.7 96.596.0
Ethanol 2.0 2.73.0
- Nitromethane 0.3 0.80.9
Temperature (C) _31.9 32.6
Barometric Pressure
(mm o~ ~g) - 746.4753.0
(kPa) (99)(100)
Temperature Corrected 32.4 33.1
to 760 mm Hg Pressure
(101 kPa)
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WOg2/02~6 _ 7 _ PCT/US91/04~2
~8~8 ~7
EXAMPLE 3
,:
This e~ample confirms the e~istence of
constant boiling or azeotrope-like compositions of
l,l-dichloro-l-fluoroethane; ethanol; and nitromethane Vi2
the method of distillation. It also illustrates that
these mixtures do not fractionate during distillation.
A 5-plate Oldershaw distillation column with a cold
water condensed automatic liquid dividing head was used
for this e~ample. The distillation column was charged
with HCFC-141b, ethanol, and nitromethane in the amounts
;~ indicated in Table III below for the starting material.
Each composition was heated under total reflux for about
an hour to ensure equilibration. A reflu~ ratio of 5:1
was employed for this particular distillation.
~; Appro~imately 50 percent of the original charges were `
collected in four similar-sized overhead fractions. Ths
compositions of these fractions were analyzed using gas
chromato~raphy. The averages of the distillate fractions
and the overhead temperatures are quite constant within
the uncertainty associated with determining the
compositions, indicating that the mi~tures are
constant-boiling or azeotrope-like.
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W092/02~6 ~ ~ - 18 - PCT/US91/04~?
TABLE III
Starting Material (wt. %)
Example HCFC-141b ETHANOL NITROMET~HANE
3 97.97 1.7a 0.25
- Distillate Composition (wt. %~
Example ~ÇFC-14lb ETHANOL NITRQMETHANE
3 98.18 1.80 0.02
1 0
~oiling Point
`~ ~oiling Barometric Corrected to
E~ample Point (C)Press~re~_ H~2~kPa~ 760mmHg(101kPa~
3 30.8 740.87(99) 31~6
From the above e~ample, it is readily apparent that
additional constant-boiling or essentially
constant-~oiling mixtures of the same components can
readily be identified by anyone of ordinary skill in this
~ art by the method described. No attempt was made to fully
;~ characterize and define the outer limits of the
composition ranqes which are constant-boiling. Anyone
~. i
-~ skilled in the art can readily ascertain other
. . .
~`~ 25 constant-boilin~ or es entially constant-boiling mi~tures
containing the same components.
:. . .
EXAMPLE 4
~-~ 30
Performance studies are conducted to evaluate the
solvent properties of the azeotrope-like compositions of
-' the in~ention. Specifically, metal coupons are cleaned
,- using the present azeotrope-like composition o~ E~ample 1
as solvent. The metal coupons are soiled with various
types of oils and heated to 93C so as to partially
, simulate the temperature attained while machining and
grinding in the presence of these oils.
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W092/02~6 - ~&~ 3 ~ 7 PCT/US91/04~
The metal coupons thus treated were degreased in a
~ simulated vapor phase degreaser machine. Condenser coils
;` are kept around the lip of a cylindrical vessel to
condense the solvent vapor which then drips down to the
vessel. The metal coupons are held in the solvent vapor
and rinsed for a period of 15 seconds to 2 minutes
depending upon the oils selected.
The cleaninq performance of the azeotrope-like
compositions is determined by visual observation of the
coupons. The azeotrope-like co~osition of Esample 1 is
. .
effective as a solvent.
~ EXAMPLE 5
: 15
Esample 4 is repeated using the azeotrope-like
composition of Example 2. The azeotrope-like composition
of E~ample 2 is effective as a solvent.
EXA~PLE76
E~ample 4 is repeated using the azeotrope-like~
~ composition of Example 3. The azeotrope-like composition
.~ of E~ample 3 is effective 2S a solvent.
EXAM~LE 7
,.~ .
A si~-ounce three-piece aerosol can is used. The
azeotrope-like compositio~ of E~ample l is weighed into a
tared aerosol can. After purging the can with
tetrafluoroethane in order to displace the air within the
container, a valve is mechanically crimped onto the can.
Liquid chlorodifluoromethane is then added through the
valve utilizing pressure burettes.
, 35
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W092/02~6 ~ 20 - PCT/VS91/04~2_
A printed circuit board having an area of 37.95
square inches and densely populated with dip sockets,
resistors~ and capacitors is precleaned by rinsing with
isopropanol ~efore wave soldering. The board is then
flu~ed and wave soldered using a Hollis TDL wave solder
machine.
The printed circuit board is then spray cleaned
using the aerosol can having the azeotrope-like
composition therein. The cleanliness of the board is
tested visually and also using an Omega-meter which
measured the ionic contamination of the board. The
azeotrope-like composition of E~ample l is particularly
useful as a solvent for spray cleaning applications.
EXAMPLE 8
Example 7 is repeated except that the
~` azeotrope-like composition of E2ample 2 is used. The
`~ 20 azeotrope-lik~ composition of Esample 2 is particularly
~ useful as a solvent for spray cleaning applications.
- EXAMPLE ~
Example 7 is repeated e~cept that the
. 25
azeotrope-like composition of E~ample 3 is used. The
azeotrope-like composition of Example 3 is particularly
~'~ useful as a solvent for spray cleaning applications.
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~ W092/02~6 - 21 - 2 ~ ~ 7~P~7~usg-/o4~2
Inhibitors may be added to the present
azeotrope-like compositions to inhibit decomposition of
the compositions; react with undesirable decomposition
products of the compositions; and/or prevent corrosion of
metal surfaces. Any or all of the following classes of
inhibitors may be employed in the invention: ~po~y
compounds such as propylene oxide; ethers such as
1-4-dioxane; unsaturated compounds such as 1,4-butyne
diol; acetals or ketals such as dipropo~y methane; ketones
such as methyl ethyl ketone; alcohols such as tertiary
amyl alcohol; esters such as triphenyl phosphite; and
amines such as triethyl amine. Other suitable inhibitors
will readily occur to those skilled in the art.
Having described the invention in detail and by
,~ reference to preferred embodiments thereof, it will be
apparent that modifications and variations are possible
~ without departing from the scope of the invention defined
;~ in the appended claims.
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