New binary azeotropes of octamethyltrisiloxane (MDM) with certain alcohols and an ester, and the use of the binary azeotropes as environmentally friendly cleaning agents are disclosed. The alcohol and ester components of the binary azeotrope are 2-methyl-1-pentanol, 1-hexanol, 1-butoxy-2-propanol, and ethyl lactate.

BACKGROUND OF THE INVENTION 
This invention is directed to an environmentally friendly cleaning agent, 
and more particularly to a cleaning agent which is a siloxane containing 
binary azeotrope. 
Because of local, state, federal, and international regulations, aimed at 
restricting the use of certain chemicals, the search for suitable 
replacements is an ever increasing dilemma faced by the chemical and 
industrial sectors. The magnitude of the problem is exemplified below. 
In the 1970s for instance, the US Environmental Protection Agency (EPA) 
named as their criteria or "hazardous pollutants" sulfur dioxide SO.sub.2 
; carbon monoxide CO; nitrogen dioxide NO.sub.2 ; ozone O.sub.3 ; 
suspended particulate with a diameter of ten microns (micrometers) or less 
PM.sub.10 ; lead Pb; and nonmethane hydrocarbons (NMHC) now known as 
"volatile organic compounds" (VOC). 
The most abundant species of photochemical smog is ozone. Ozone precursors 
are VOC, nitric oxide NO, and NO.sub.2. In order to reduce ozone in a 
polluted atmosphere, reductions in VOC and nitrogen oxide NO.sub.x (NO and 
NO.sub.2) precursors has been required. 
Solar energy is absorbed by the surface of the earth and re-emitted as 
radiation. Certain gases in the atmosphere are capable of absorbing the 
re-emitted radiation and translating it into heat (THE GREENHOUSE EFFECT). 
The result is a higher atmospheric temperature (GLOBAL WARMING) than would 
be obtained in the absence of these "GREENHOUSE GASES". Accordingly, 
reductions in the emission of such gases has been required, including 
carbon dioxide CO.sub.2, methane CH.sub.4, nitrous oxide N.sub.2 O, ozone, 
and a variety of chloro, fluoro, and chlorofluorocarbons (CFC) such as 
methylchloroform CH.sub.3 CCl.sub.3 (MCF), carbon tetrachloride CCl.sub.4, 
C.sub.2 HF.sub.5 (HCFC-125), C.sub.2 H.sub.2 F.sub.4 (HFC-134a), and 
chlorofluorocarbons such as CFCl.sub.3 (CFC-11), CF.sub.2 Cl.sub.2 
(CFC-12), C.sub.2 ClF.sub.5 (CFC-115), CHClF.sub.2 (HCFC-22), C.sub.2 
HCl.sub.2 F.sub.3 (HCFC-123), C.sub.2 HClF.sub.4 (HCFC-124), and C.sub.2 
Cl.sub.3 F.sub.3 (CFC-113). 
Stratospheric ozone is a natural shield against the penetration of uv-light 
in the rays of the sun. There has been concern that any process which 
depletes stratospheric ozone will increase the amount of uv-B radiation 
(293-320 nanometers/2930-3200 angstroms) reaching the surface of the 
earth. Increased uv-B radiation may lead to the increased incidence of 
skin cancer. CFC's diffuse through the troposphere (up to 10 miles/16 
kilometers) and into the mid-stratosphere (up to 30 miles/48 kilometers), 
where they are photolyzed by uv radiation and destroy ozone molecules. 
Because of STRATOSPHERIC OZONE DEPLETION, mandates such as the 1990 Clean 
Air Act Amendment contain a phaseout schedule for CFC's, halons 
(bromochlorofluorocarbons and bromofluorocarbons), carbon tetrachloride, 
and methylchloroform. 
These are only a few of the problems faced by the chemical and industrial 
sectors in finding suitable replacements for such chemicals. Of particular 
interest according to the present invention, however, is the VOC aspect of 
the problem and the provision of a suitable substitute material. 
Thus, "volatile organic compounds" (VOC) and "volatile organic material" 
(VOM) are defined in the United States by Federal statute in Title 40 CFR 
51.100(s) to be any compound of carbon, excluding carbon monoxide, carbon 
dioxide, carbonic acid, metallic carbides or carbonates, and ammonium 
carbonate, which participates in atmospheric photochemical reactions. The 
definition excludes certain compounds and classes of compounds as VOC or 
VOM. 
Scientifically, VOC has been defined as any compound of carbon that has a 
vapor pressure greater than 0.1 millimeters of mercury (13.3 Pa) at a 
temperature of twenty degrees Centigrade and a pressure of 760 millimeters 
mercury (101.3 kPa); or if the vapor pressure is unknown, a compound with 
less than twelve carbon atoms. "Volatile organic content" is the amount of 
volatile organic compounds (VOC) as determined according to EPA Test 
Method 24 or 24A, the procedures of which are set forth in detail in Title 
40 CFR Part 60, Appendix A. 
Reduction of VOC has already been mandated in several states, and 
regulations in California for example, require less than about 180 grams 
of volatile material per liter of any product which enters the atmosphere. 
This amount can be determined by baking ten grams of a product in an oven 
at 110 degrees Centigrade for one hour. The amount of solids which remain 
is subtracted from the total of the ten grams which was tested. 
Calculations are based on the weight of the volatile that have evaporated, 
and the amount is reported as grams per liter. 
The EPA has identified many volatile organic compounds (VOC) present in 
consumer products among which are such common solvents as ethanol, 
isopropyl alcohol, kerosene, and propylene glycol; and common hydrocarbon 
solvents such as isobutane, butane, and propane, which are often employed 
as propellants in various aerosol sprays. 
The state of California under the auspices of the California Air Regulation 
Board (CARB), has proposed standards which would limit and reduce the 
amount of volatile organic compounds (VOC) permitted in various chemically 
formulated products used by household and institutional consumers. These 
regulations cover products such as detergents; cleaning compounds; 
polishes; floor products; cosmetics; personal care products; home, lawn 
and garden products; disinfectants; sanitizers; and automotive specialty 
products. 
These CARB type standards would effect such widely used common consumer 
products such as shaving lather, hair spray, shampoos, colognes, perfumes, 
aftershave lotions, deodorants, antiperspirants, suntan preparations, 
breath fresheners, and room deodorants. 
Replacement of "outlawed" chemicals with certain volatile methyl siloxanes 
(VMS) as a solvent substitute is a viable approach. In fact, the EPA in 
Volume 59, No. 53, of the Federal Register, 13044-13161, (Mar. 18, 1994), 
has indicated at Page 13091 that "Cyclic and linear volatile methyl 
siloxanes (VMSs) are currently undergoing investigation for use as 
substitutes for Class I compounds in metals, electronic and precision 
cleaning. Because of their chemical properties, these compounds show 
promise as substitutes for cleaning precision guidance equipment in the 
defense and aerospace industries. In addition, the volatile methyl 
siloxanes have high purity and are therefore relatively easy to recover 
and recycle. In the cleaning system using VMSs, the fluids are used to 
clean parts in a closed header system using a totally enclosed process. 
The parts are drained and then dried using vacuum baking". 
At Pages 13093-13094, the EPA goes on to state that the "volatile methyl 
siloxanes dodecamethylcyclohexasiloxane, hexamethyldisiloxane, 
octamethyltrisiloxane, and decamethyltetrasiloxane are acceptable 
substitutes for CFC-113 and MCF" for cleaning in closed systems, in the 
metals cleaning sector, the electronics cleaning sector, and the precision 
cleaning sector; under the EPA Significant New Alternatives Policy (SNAP). 
At Page 13137, the EPA notes that with regard to the two volatile methyl 
siloxanes octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, 
that the "Agency has completed review of data, and intends under separate 
rule-making to propose these chemicals as acceptable with the use 
condition that the company-set exposure limits must be met". 
In addition, a petition to the EPA filed in late 1992 is pending seeking 
exemption of these volatile methyl siloxanes (VMS) from regulation as VOC. 
The basis for the petition is that the volatile methyl siloxanes do not 
contribute to, and in some cases actually inhibit the formation of 
tropospheric ozone. Thus, the volatile methyl siloxanes have a lower ozone 
formation potential than ethane, which is the most reactive compound on a 
list of "exempt" VOC. 
Furthermore, these volatile methyl siloxanes (VMS) have an atmospheric 
lifetime of between 10 to 30 days. Consequently, VMS compounds do not 
contribute significantly to global warming. Volatile methyl siloxanes have 
no potential to deplete stratospheric ozone due to their short atmospheric 
lifetimes so that they will not rise and accumulate in the stratosphere. 
VMS compounds also contain no chlorine or bromine atoms. 
Volatile methyl siloxane compounds (VMS) neither attack the ozone layer nor 
do they contribute to tropospheric ozone formation (Smog), and they have 
minimum GLOBAL WARMING potential. Volatile methyl siloxane compounds are 
hence unique in possessing these three attributes simultaneously. 
Thus, it should be apparent that volatile methyl siloxanes provide a viable 
solution to the problem of finding a suitable replacement for "outlawed" 
chemicals heretofore commonly used as cleaning agents. 
SUMMARY OF THE INVENTION 
The invention relates to new binary azeotropes of a volatile methyl 
siloxane with certain alcohols and an ester. 
The invention also relates to the use of these new siloxane containing 
azeotropes as an environmentally friendly cleaning agent. 
As cleaning agents, the new azeotropes can be used to remove contaminants 
from any surface, but are particularly useful in applications related to 
defluxing and precision cleaning; low-pressure vapor degreasing; and vapor 
phase cleaning; for example. 
The unexpected advantages and benefits of these new siloxane containing 
azeotropes as cleaning agents include enhanced solvency power, and the 
maintenance of a constant solvency power following evaporation, which may 
occur during applications involving vapor phase cleaning, distillative 
regeneration, and wipe cleaning. 
Because the cleaning agent according to the invention is an azeotrope, it 
possesses the added advantage and benefit of being more easily recovered 
and recirculated. Thus, the azeotrope can be separated from the 
contaminated cleaning bath effluent after its use in the cleaning process. 
By simple distillation, its regeneration is facilitated whereby it may be 
recirculated in the system as fresh cleaning agent influent. 
In addition, these azeotropes provide an unexpected advantage in being 
higher in siloxane fluid content and correspondingly lower in alcohol 
content, than azeotropes of siloxane fluids and lower molecular weight 
alcohols such as ethanol. The surprising result is that the azeotropes of 
the invention are less inclined to generate tropospheric ozone and smog. 
These and other features, objects, and advantages, of the present invention 
will become more apparent from a consideration of the following detailed 
description thereof. 
DETAILED DESCRIPTION OF THE INVENTION 
An azeotrope is a mixture of two or more liquids, the composition of which 
does not change upon distillation. For example, a mixture of 95% ethanol 
and 5% water boils at a lower temperature of 78.15.degree. Centigrade, 
than either pure ethanol which boils at a temperature of 78.3.degree. 
Centigrade, or pure water which boils at a temperature of 100.degree. 
Centigrade. Such liquid mixtures behave like a single substance in that 
the vapor produced by partial evaporation of liquid has the same 
composition as the liquid. Thus, these mixtures distill at a constant 
temperature without change in their composition and cannot be separated by 
normal distillation procedures. 
Azeotropes exist in systems containing two liquids (A and B) termed binary 
azeotropes, in systems containing three liquids (A, B, and C) termed 
ternary azeotropes, and in systems containing four liquids (A, B, C, and 
D) termed quaternary azeotropes. The azeotropes of this invention are 
binary azeotropes. 
However, as is well known in the art, azeotropism is an "unpredictable 
phenomenon", and each azeotropic composition must be discovered. This 
phenomenon of "unpredictability" is documented in the prior art, and 
reference may be had to U.S. Pat. No. 4,157,976 (Column 1 lines 47-51), as 
one example. Reference may also be had to U.S. Pat. No. 4,155,865 for 
supporting documentation in this regards. 
For purposes of this invention, a mixture of two or more components is 
azeotropic, if it vaporizes with no change in the composition of the vapor 
from the liquid. Specifically, azeotropic mixtures include both mixtures 
that boil without changing composition, and mixtures that evaporate at a 
temperature below the boiling point without changing composition. 
Accordingly, an azeotropic mixture may include mixtures of two components 
over a range of proportions where each specific proportion of the two 
components is azeotropic at a certain temperature, but not necessarily at 
other temperatures. 
Azeotropes vaporize with no change in their composition. If the applied 
pressure is above the vapor pressure of the azeotrope, the azeotrope 
evaporates without change. If the applied pressure is below the vapor 
pressure of the azeotrope, the azeotrope boils or distills without change. 
The vapor pressure of low boiling azeotropes is higher, and the boiling 
point is lower than that of the individual components. In fact, the 
azeotropic composition has the lowest boiling point of any composition of 
its components. Thus, the azeotrope can be obtained by distillation of a 
mixture whose composition initially departs from that of the azeotrope. 
Since only certain combinations of components can form azeotropes, the 
formation of an azeotrope cannot be reliably predicted without 
experimental vapor-liquid-equilibria (VLE) data, that is vapor and liquid 
compositions at constant total pressure or temperature for various 
mixtures of the components. 
The composition of some azeotropes is invariant to temperature, but in many 
cases, however, the azeotropic composition shifts with temperature. The 
azeotropic composition as a function of temperature can be determined from 
high quality VLE data at a given temperature. Commercial software is 
available to make such determinations. The ASPENPLUS.RTM. program of Aspen 
Technology, Inc., of Cambridge, Mass., is an example of such a program. 
Given experimental data, such programs can calculate parameters from which 
complete tables of composition and vapor pressure may be generated. This 
allows a user of the system to determine where an azeotropic composition 
is located. 
The volatile methyl siloxane used to form the azeotropes according to the 
present invention, is the linear short chain siloxane fluid 
octamethyltrisiloxane, which has the formula (CH.sub.3).sub.3 
SiO(CH.sub.3).sub.2 SiOSi(CH.sub.3).sub.3. Octamethyltrisiloxane has a 
viscosity of 1.0 centistoke (mm.sup.2 /s) measured at 25.degree. 
Centigrade. Octamethyltrisiloxane is sometimes abbreviated in the 
literature as "MDM", which indicates the presence in the molecule of one 
difunctional "D" unit (CH.sub.3).sub.2 SiO.sub.2/2 and two monofunctional 
"M" units (CH.sub.3).sub.3 SiO.sub.1/2, shown below. 
##STR1## 
Octamethyltrisiloxane (MDM) is a clear fluid, essentially odorless, 
nontoxic, nongreasy, nonstinging, and it is nonirritating to skin. It will 
leave substantially no residue after thirty minutes at room temperature, 
when one gram of the fluid is placed at the center of No. 1 circular 
filter paper, with a diameter of 185 millimeters and supported at its 
perimeter in open room atmosphere. 
In our prior copending application U.S. Ser. No. 08/260,423, filed Jun. 15, 
1994, we discovered and described azeotropes of hexamethyldisiloxane with 
three alcohols, namely, 3-methyl-3-pentanol, 2-pentanol, and 
1-methoxy-2-propanol. The binary azeotropes according to the present 
invention also includes an alcohol. In addition, we have discovered 
additional new alcohols and an ester, which form azeotropes with 
octamethyltrisiloxane, instead of hexamethyldisiloxane. 
The alcohol according to this invention can be one of 2-methyl-1-pentanol 
which has the formula C.sub.3 H.sub.7 CH(CH.sub.3)CH.sub.2 OH; 1-hexanol 
(amyl carbinol) which has the formula CH.sub.3 (CH.sub.2).sub.4 CH.sub.2 
OH; and the alkoxy containing aliphatic alcohol 1-butoxy-2-propanol which 
has the formula C.sub.4 H.sub.9 OCH.sub.2 CH(CH.sub.3)OH. The ester is the 
ethyl ester of the alpha-hydroxy acid, lactic acid. The ester ethyl 
lactate (2-hydroxypropanoic acid ethyl ester) has the formula CH.sub.3 
CH(OH)COOC.sub.2 H.sub.5. 
The boiling points of each of the liquids in degrees Centigrade measured at 
the standard barometric pressure of 760 millimeters of mercury (101.3 kPa) 
are 152.6.degree. for octamethyltrisiloxane; 148.degree. for 
2-methyl-1-pentanol; 157.2.degree. for 1-hexanol; 170.degree. for 
1-butoxy-2-propanol; and 154.degree. for ethyl lactate. 
An especially significant, surprising, and unexpected result flows from the 
use of the azeotropes of the invention is that they possess an enhanced 
solvency power in comparison to the use of octamethyltrisiloxane alone. 
Yet at the same time, the azeotropes exhibit a mild solvency power making 
them useful for cleaning delicate surfaces without doing harm to the 
surface to be cleaned. 
The following examples are set forth for the purpose of illustrating the 
invention in more detail. New homogeneous binary azeotropes of 
octamethyltrisiloxane were discovered with three different alcohols and an 
ester. These azeotropes contained 8 to 40 percent by weight of 
2-methyl-1-pentanol; 5 to 28 percent by weight of 1-hexanol; 2 to 13 
percent by weight of 1-butoxy-2-propanol; and 36 to 46 percent by weight 
of ethyl lactate; respectively with octamethyltrisiloxane. 
The azeotropes were homogeneous in that they had a single liquid phase at 
both the azeotropic temperature and also at room temperature. Homogeneous 
azeotropes are more desirable than heterogeneous azeotropes, especially 
for cleaning applications, since homogeneous azeotropes exist as one 
liquid phase instead of two phases as the heterogeneous azeotrope. Each 
phase of a heterogeneous azeotrope differs in its cleaning power, and 
therefore the cleaning performance of a heterogeneous azeotrope will be 
difficult to reproduce because it is dependent upon consistent mixing of 
the phases. Single phase (homogeneous) azeotropes are also more useful 
than multi-phase (heterogeneous) azeotropes, since they can be transferred 
between locations with more facility. 
Each homogeneous azeotrope was found to exist over a particular temperature 
range. Within that range, the azeotropic composition shifted somewhat with 
temperature. The compositions were azeotropic within the range of zero to 
162 degrees Centigrade inclusive.

EXAMPLE I 
There was employed a single-plate distillation apparatus for measuring 
vapor-liquid equilibria. The liquid mixture was boiled and the vapor 
condensed into a small receiver which had an overflow path to recirculate 
back to the boiling liquid. When equilibrium was established, samples of 
the boiling liquid and of the condensed vapor were separately removed and 
quantitatively analyzed by gas chromatography (GC). The measured 
temperature, ambient pressure, and the liquid and vapor compositions, were 
obtained at several different initial compositional points. These data 
were used to determine whether an azeotropic composition existed. The 
azeotropic composition at different temperatures was determined by using 
the same data with the assistance of the ASPENPLUS.RTM. software program 
to perform the quantitative determinations. The azeotropic compositions 
are shown in Table I. 
In Table I, "MDM" is used to designate the weight percent in the azeotropic 
composition of octamethyltrisiloxane. The vapor pressure VP in Table I is 
shown in Torr pressure units (1 Torr=0.133 kPa/1 mmHg). The accuracy in 
determining the azeotropic compositions is approximately plus or minus 
about two weight percent. 
TABLE I 
______________________________________ 
ALCOHOL/ TEMPERATURE VP WEIGHT 
ESTER .degree.C. (Torr) % MDM 
______________________________________ 
2-methyl-1-pentanol 
148.3 1000 60 
139.4 760 61 
125 473.9 65 
100 189.3 70 
75 65.1 75 
50 18.6 81 
25 4.1 87 
0 0.7 92 
1-hexanol 153.2 1000 72 
143.9 760 75 
125 415.9 78 
100 167.7 83 
75 58.2 89 
50 16.8 95 
1-butoxy-2-propanol 
162.3 1000 87 
151.8 760 89 
125 347.7 94 
100 148.8 98 
ethyl lactate 
148.7 1000 61 
139.4 760 63 
125 486.3 63 
100 205.7 64 
75 76.1 64 
50 23.8 63 
25 6.0 59 
0 1.1 54 
______________________________________ 
The azeotropic compositions of the invention are particularly useful for 
cleaning precision articles made of metal, ceramic, glass, and plastic. 
Examples of such articles are electronic and semiconductor parts, electric 
and precision machinery parts such as ball bearings, optical parts and 
components such as lenses, photographic and camera parts and equipment, 
and military and space hardware such as precision guidance equipment used 
in the defense and aerospace industries. 
One especially useful application of the azeotropic compositions of the 
invention is the cleaning and removal of fluxes used in mounting and 
soldering electronic parts on printed circuit boards. For example, a 
solder is often used in making a mechanical, electromechanical, or 
electronic connection. Thus, in making electronic connections, the 
components are attached to the conductor paths of a printed wiring 
assembly by wave soldering. The solder used is usually a tin-lead alloy, 
with the aid of a flux which is rosin based. Rosin is a complex mixture of 
isomeric acids principally abietic acid. These rosin fluxes often also 
contain activators such as amine hydrohalides and organic acids. The 
function of the flux is to react with and remove surface compounds such as 
oxides. It also reduces the surface tension of the molten solder alloy, 
and prevents oxidation during the heating cycle by providing a surface 
blanket to the base metal and solder alloy. 
After the soldering operation, however, it is usually necessary to perform 
a final cleaning of the assembly. The azeotropic compositions of the 
invention are useful as a final cleaner. They remove any flux residues and 
oxides formed on areas unprotected by the flux during soldering which are 
corrosive or would cause malfunctioning or short circuiting of electronic 
assemblies. In such applications, the azeotropic compositions can be used 
as cold cleaners, vapor degreasers, or accompanied with ultrasonic energy. 
The azeotropic compositions of this invention can also be used to remove 
carbonaceous materials from the surface of the above types of articles, as 
well as from the surface of various other industrial articles. Exemplary 
of carbonaceous materials are any carbon containing compound or mixtures 
of carbon containing compounds, which are soluble in one or more of the 
common organic solvents, such as hexane, toluene, or 
1,1,1-trichloroethane. 
For the purpose of further illustrating the invention, the use of the 
azeotropes for cleaning was tested using a rosin-based solder flux as the 
soil. The cleaning tests were at 22.degree. Centigrade in an open bath 
with no distillative recycle of the azeotrope. All of the azeotropes were 
found to remove flux, although not each of the azeotropes was equally 
effective. For purposes of comparison, a CONTROL composition consisting of 
only octamethyltrisiloxane was included in these cleaning tests, and is 
shown in Table II as composition "No. 6". 
EXAMPLE II 
Kester No. 1544 rosin flux was mixed with 0.05 weight percent of a 
nonreactive low viscosity silicone glycol flow-out additive. The mixture 
was applied as a uniform thin layer to a 2".times.3" (5.1.times.7.6 cm) 
area of an Aluminum Q panel with a No. 36 Industry Tech Inc. draw-down 
rod. An activated rosin-based solder flux commonly used for electrical and 
electronic assemblies was employed. It is a product manufactured and sold 
by Kester Solder Division, Litton Industries, Des Plaines, Ill., USA. The 
approximate composition of the flux was fifty weight percent of a modified 
rosin, twenty-five weight percent of ethanol, twenty-five weight percent 
of 2-butanol, and one weight percent of a proprietary activator. The 
coating was allowed to dry at room temperature and cured at 100.degree. C. 
for ten minutes in an air oven. The Aluminum Q panel was placed in a large 
beaker which had a magnetic stirring bar at the bottom and one-third 
filled with the azeotropic composition. Cleaning was conducted while 
rapidly stirring at room temperature, even when cleaning with the higher 
temperature azeotropic compositions. The panel was removed at timed 
intervals, dried at 80.degree. C. for ten minutes, weighed, and reimmersed 
for additional cleaning. The initial coating weight and the weight loss 
were measured as a function of cumulative cleaning time, and this data is 
shown in Table II. 
In Table II, the alcohols and the ester are abbreviated as "2-M-1-P" for 
2-methyl-1-pentanol; "HEXANOL" for 1-hexanol; "1-B-2-P" for 
1-butoxy-2-propanol; and "ESTER" for ethyl lactate. The "WT %" shown in 
Table II refers to the weight percent of the alcohol or ester in the 
azeotrope. The "TEMP" is the azeotropic temperature in Centigrade degrees 
of the azeotrope. The "WT" is the initial weight of the coating in grams. 
The time shown in Table II is cumulative time measured after the elapse of 
one minute, five minutes, ten minutes, and thirty minutes. 
As noted above, composition No. 6 in Table II was a CONTROL consisting of 
one hundred percent octamethyltrisiloxane (MDM). It should be apparent 
from Table II that all of the azeotropic compositions 1 to 5 in Table II 
were much more effective cleaners than composition No. 6. 
TABLE II 
______________________________________ 
CLEANING EXTENT AT ROOM TEMPERATURE (22.degree. C.) 
% REMOVED 
WT LI- (Time-min) 
No. % QUIDS TEMP WT 1 5 10 30 
______________________________________ 
1 39% 2-M-1-P 139.4 0.3096 
85.4 99.8 99.9 
-- 
2 13% 2-M-1-P 25.0 0.3011 
79.7 96.6 98.1 
98.8 
3 25% HEX- 143.9 0.2993 
77.0 96.6 99.8 
-- 
ANOL 
4 11% 1-B-2-P 151.8 0.3445 
13.9 65.9 73.3 
86.3 
5 37% ESTER 139.4 0.3117 
93.0 99.8 100.2 
-- 
6 0% 100% -- 0.3460 
0.7 1.5 1.9 3.2 
MDM 
______________________________________ 
These azeotropes have several advantages for cleaning, rinsing, or drying. 
Thus, the azeotropic composition can easily be regenerated by distillation 
so that the performance of the cleaning mixture can be restored after a 
period of use. The performance factors which can be affected by the 
composition of azeotropic mixtures include bath life, cleaning speed, lack 
of flammability when only one component is non-flammable, and lack of 
damage to sensitive parts. 
In vapor phase degreasing equipment, the azeotropic mixture can be 
continually restored by continuous distillation at atmospheric or at 
reduced pressure, and can be continually recycled in the cleaning 
equipment. In this type of equipment, cleaning or rinsing can be conducted 
at the boiling point by plunging the part to be cleaned or rinsed in the 
boiling liquid, or by allowing the refluxing vapor to condense on the cold 
part. Alternatively, the part may be immersed in a cooler bath that is 
continually fed by fresh condensate, and the dirty overflow liquid is 
returned to a boil sump. 
If the azeotrope is used in an open system, the composition and the 
performance of the azeotrope will remain constant even though evaporative 
losses occur. Such a system can be operated at room temperature when used 
in a ambient cleaning bath, or when used as a wipe-on-by-hand cleaner. The 
cleaning bath can also be operated at elevated temperatures which are 
below the boiling point, although often cleaning, rinsing, or drying, 
occurs faster at an elevated temperature, and hence is desirable when the 
part to be cleaned and the equipment permit. 
The azeotropes of the invention can be used for cleaning in a variety of 
ways beyond those shown by the foregoing examples. Thus, cleaning can be 
conducted by using a given azeotrope at or near its azeotropic temperature 
or at some other temperature. 
Other processes of use of the azeotropes of the invention include the 
distillative recycle of a spent azeotrope at atmospheric pressure, or at a 
reduced pressure. In addition, cleaning may be conducted by immersing the 
part to be cleaned in quiescent or boiling liquid, as well as in the vapor 
condensation region above the boiling liquid. In the later case, the part 
is cleaned in a continually renewed liquid of maximum cleaning power. 
In cleaning applications according to the invention, only the azeotrope may 
be used, however if desired, small amounts of one or more organic liquid 
additives can be combined with the azeotrope. Organic liquid additives 
contemplated according to the invention, are compounds capable of 
imparting an enhanced oxidative stability, corrosion inhibition, or 
solvency enhancement. 
Oxidative stabilizers inhibit the slow oxidation of organic compounds such 
as alcohols and esters. Corrosion inhibitors inhibit metal corrosion by 
traces of acids that may be present, or which slowly form in alcohols and 
esters. Solvency enhancers increase solvency power by adding more powerful 
solvents to a starting solvent. These additives can mitigate any undesired 
effects of the alcohol and ester components of the new azeotropes of the 
invention, which alcohol and ester component are not as resistant to 
oxidative degradation as octamethyltrisiloxane. 
Numerous additives are suitable for combination with the azeotropes of the 
invention, and octamethyltrisiloxane is miscible with small amounts of 
many such additives. However, regardless of the additive, it must be one 
in which the resulting liquid mixture of the selected additive and the 
azeotrope, is homogeneous and single phased. 
Among the oxidative stabilizers that may be employed in amounts of about 
0.05 to 5 percent by weight, are phenols such as trimethylphenol, 
cyclohexylphenol, thymol, 2,6-di-t-butyl-4-methylphenol, 
butylhydroxyanisole, and isoeugenol; amines such as hexylamine, 
pentylamine, dipropylamine, diisopropylamine, diisobutylamine, 
triethylamine, tributylamine, pyridine, N-methylmorpholine, 
cyclohexylamine, 2,2,6,6-tetramethylpiperidine, and 
N,N'-diallyl-p-phenylenediamine; and triazoles such as benzotriazole, 
2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and chlorobenzotriazole. 
Among the corrosion inhibitors that may be employed in amounts of about 0.1 
to 5 percent by weight, are aliphatic nitro compounds such as 
nitromethane, nitroethane, and nitropropane; acetylene alcohols such as 
3-methyl-1-butene-3-ol, and 3-methyl-1-pentene-3-ol; epoxides such as 
glycidol, methyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl 
ether, 1,2-butylene oxide, cyclohexene oxide, and epichlorohydrin; ethers 
such as dimethoxymethane, 1,2-dimethoxyethane, 1,4-dioxane, and 
1,3,5-trioxane; unsaturated hydrocarbons such as hexene, heptene, octene, 
2,4,4-trimethyl-1-pentene, pentadiene, octadiene, cyclohexene, and 
cyclopentene; olefin based alcohols such as allyl alcohol, and 
1-butene-3-ol; and acrylic acid esters such as methyl acrylate, ethyl 
acrylate, and butyl acrylate. 
Among the solvency enhancers that may be employed in amounts of about 0.1 
to 10 percent by weight, are hydrocarbons such as pentane, isopentane, 
hexane, isohexane, and heptane; nitroalkanes such as nitromethane, 
nitroethane, and nitropropane; amines such as diethylamine, triethylamine, 
isopropylamine, butylamine, and isobutylamine; alcohols such as methanol, 
ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, and isobutanol; 
ethers such methyl Cellosolve.RTM., tetrahydrofuran, and 1,4-dioxane; 
ketones such as acetone, methyl ethyl ketone, and methyl butyl ketone; and 
esters such as ethyl acetate, propyl acetate, and butyl acetate. 
Other variations and modifications may be made in the compounds, 
compositions, and methods described herein, without departing from the 
essential features and concepts of the present invention. 
The forms of the invention described herein are exemplary only, and are not 
intended as limitations on the scope of the invention as defined in the 
appended claims.