WO1991013969A1

WO1991013969A1 - Stabilized constant-boiling, azeotrope or azeotrope-like compositions of dichlorotrifluoroethane; 1,1-dichloro-1-fluoroethane; with methanol and/or ethanol

Info

Publication number: WO1991013969A1
Application number: PCT/US1991/000846
Authority: WO
Inventors: Robert Alexander Gorski
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1990-03-13
Filing date: 1991-02-13
Publication date: 1991-09-19
Anticipated expiration: 1992-09-13
Also published as: AU7309991A

Abstract

Stabilized azeotropic or azeotrope-like compositions of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol with effective stabilizing amounts of nitromethane, 1,2-propylene oxide, 1,2-butylene oxide, diisopropylamine, 2,6-dimethylpiperidine and a lower alkoxyphenol in specified combinations.

Description

TITLE

STABILIZED CONSTANT-BOILING, AZEOTROPE OR AZEOTROPE-LIKE

COMPOSITIONS OF DICHLOROTRIFLUOROETHANE;

1.1-DICHLORO-1-FLUOROETHANE; WITH METHANOL AND/OR ETHANOL

Background of the Invention

As modern electronic circuit boards evolve toward increased circuit and component densities, thorough board cleaning after soldering becomes a more important criterion. Current industrial processes for soldering electronic

components to circuit boards involve coating an entire circuit board with a flux composition and, thereafter, passing the coated side of the board over preheaters and then through molten solder. The flux composition cleans the conductive metal parts and promotes solder adhesion. Commonly used fluxes consist, for the most part, of rosin used alone or rosin with activating additives, such as amine hydrochlorides or oxalic acid derivatives.

After soldering, which thermally degrades part of the rosin, flux and flux residues are often removed from the board with an organic solvent composition. Since requirements for the removal of contaminants from circuit boards are very stringent, most current industrial circuit board cleaning processes involve the use of vapor defluxing techniques. In the conventional operation of a vapor defluxer, the soldered circuit board is passed through a sump of boiling organic solvent, which removes the bulk of the rosin—including thermally degraded rosin—and thereafter, through a sump which contains freshly distilled solvent and finally through solvent vapor above the boiling simp, which provides a final rinse with a clean, distilled solvent which has condensed on the circuit board. Additionally, the circuit board could also be sprayed with distilled solvent, if required, before the final rinse. While azeotrope or azeotrope-l ike compositions of dichlorotrifluoroethane and 1, 1-dichloro-1-fluoroethane with methanol and/or ethanol are excellent solvent systems for cleaning circuit boards, for practical industrial use these solvent systems, as is the case with many solvent systems, should be stabil ized against compositional changes during both use and long term storage. Changes, such as oxidation, polymerization, component interactions and the l ike, may generate products which adversely affect the circuit boards being cleaned or the solvent compositions themselves.

It is therefore an object of the present invention to provide azeotrope or azeotrope-like compositions of

dichlorotrifluoroethane end 1, 1-dichloro-1-fluoroethane with methanol and/or ethanol which are compositionally stable during use and long term storage and which minimize the formation of undesirable reaction products, which may adversely affect their storage and use, e.g. , for electronic circuit board cleaning.

Summary of the Invention

Stabilized azeotrope or azeotrope-like compositions have been discovered comprising effective amounts of

dichlorotrifluoroethane and 1, 1-dichloro-1-fluoroethane with methanol and/or ethanol and effective stabilizing amounts of: nitromethane, a lower al koxyphenol , an epoxide selected from the group consisting of 1,2-propylene oxide and 1,2-butylene oxide and an amine selected from the group consisting of di isopropylamine and 2,6-dimethylpiperidine; 1,2-butylene oxide and/or 2,6-dimethylpiperidine; nitromethane and at least one compound selected from the group consisting of 1,2-propylene oxide, 1,2-butylene oxide, diisopropylamine and

2,6-dimethylpiperidine; n itromethane, 1,2-propylene oxide and 1,2-butylene oxide; nitromethane, diisopropylamine and an epoxide selected from the group consisting of 1,2-propylene oxide and 1,2-butylene oxide; nitromethane, a lower alkoxyphenol and at least one amine selected from the group consisting of diisopropylamine and 2,6-dimethylpiperidine.

Also included in this invention are stabilized azeotrope or azeotrope-like composi tions consisting essentially of about 3 to 70 weight percent dichlorotrifluoroethane, about 25 to 94.9 weight percent 1,1-dichloro-1-fluoroethane and about 0.1 to 5 weight percent methanol and/or ethanol and effective stabilizing amounts of nitromethane, a lower alkoxyphenol , an epoxide selected from the group consisting of 1,2-propylene oxide and 1,2-butylene oxide and an amine selected from the group consisting of diisopropylamine and

2,6-dimethylpiperidine. Also included in this invention are stabilized azeotrope or azeotrope-like compositions consisting essentially of about 30 to 70 weight percent

dichlorotrifluoroethane, about 25 to 69 weight percent

1,1-dichloro-1-fluoroethane and about 1 to 5 weight percent methanol and/or ethanol and effective stabilizing amounts of nitromethane, a lower al koxyphenol , an epoxide selected from the group consisting of 1,2-propylene oxide and 1,2-butylene oxide and an amine selected from the group consisting of diisopropylamine and 2,6-dimethylpiperidine.

Detailed Description of the Invention

By effective amounts is meant the amounts of each component of dichlorotrifluoroethane,

1,1-dichloro-1-fluoroethane, methanol and/or ethanol , which, when combined, result in the formation of an azeotrope or azeotrope-like composition.

By effective stabilizing amounts is meant the amounts of the following:

o nitromethane, a lower alkoxyphenol , an epoxide selected from the group consisting of 1,2-propylene oxide and

1,2-butylene oxide and an amine selected from the group consisting of diisopropylamine and 2,6-dimethylpiperidine; or o 1,2-butylene oxide and/or 2,6-dimethylpiperidine; or o nitromethane and et least one compound selected from the group consisting of 1,2-propylene oxide, 1,2-butylene oxide, diisopropylamine and 2,6-dimethylpiperidine; or

o nitromethane, 1,2-oropylene oxide and 1,2-butylene oxide; or

o nitromethane, diisopropylamine and an epoxide selected from the group consisting of 1,2-propylene oxide and

1,2-butylene oxide; or

o nitromethane, a lower alkoxyphenol and at least one amine selected from the group consisting of diisopropylamine and 2,6-dimethylpiperidine;

which, when combined with the azeotrope or azeotrope-l ike compositions of dichlorotrifluoroethane and

1,1-dichloro-1-fluoroethane with either methanol and/or ethanol , al low such azeotrope or azeotrope-l ike compositions to be used and stored cαmiercially, i .e. , provide commercially acceptable appearances, corrosivities and resistances to loss of integrity.

The language "azeotrope or azeotrope-l ike composition consisting essentially of..." is intended to include mixtures which contain all the components of the azeotrope described herein (in any amounts) and which, if fractionally distilled, would produce an azeotrope containing all the components of the azeotrope in at least one fraction, alone or in combination with other compounds, e.g. , one or more which distil l at substantial ly the same temperature as said fraction.

By lower al koxyphenol is meant methoxyphenol ,

ethoxyphenol , propoxyphenol and/or butoxyphenol . The preferred lower al koxyphenol is 4-methoxyphenol .

The term dichlorotrifluoroethane is meant to include either 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) and/or

1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a) and mixtures of

HCFC-123 and HCFC-123a. Commercial ly available HCFC-123 may contain as much as about 20.0 wt. %

1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a) which mixture is also covered by the language dichlorotrifluoroethane as well as the inclusion of minor amounts of other materials which do not significantly alter the azeotrope or azeotrope-like character of the compositions of the instant invention.

The preferred stabilized compositions of the present invention comprise aotoixtures of effective amounts of

dichlorotrifluoroethane a.ιd 1,1-dichloro-l-fluoroethane with methanol and/or ethanol, which compositions form azeotropes or azeotrope-like compositions and may contain about 0.1 to 0.8 weight percent of nitromethane, about 0.05 to 0.4 weight percent of 1,2-propylene oxide and/or 1,2-butylene oxide, about 0.025 to 0.2 weight percent of diisopropylamine and/or

2,6-dimethylpiperidine and about 0.002 to 0.016 weight percent a lower alkoxyphenol, said weight percentages are based on the weight of the azeotrope or azeotrope-like composition.

As recognized in the art, an azeotrope or

azeotrope-like composition is an admixture of two or more different components which, when in liquid form, under given pressure, will boil at substantially constant temperature, which temperature may be higher or lower than the boiling temperature of the components and which will provide a vapor composition essentially identical to the liquid composition undergoing boiling. The essential features of an azeotrope or azeotrope-like composition are that at a given pressure, the boiling point of the liquid composition is fixed and the composition of the vapor above the boiling composition is essentially that of the boiling liquid composition, i.e.

substantially no fractionalon of the liquid components occurs.

It is also recognized in the art that both the boiling point and weight percentages of each component of the azeotrope or azeotrope-like composition may change when it is subjected to boiling at different pressures. Thus, an azeotrope or azeotrope-like composition may be defined in terms of the unique relationship which exists among components, or in terms of component compositional ranges, or in terms of each component's weight percentages in the composition,

characterized by a fixed boiling point at a specified pressure.

The present azeotrope or azeotrope-like compositions comprise aαtoixtures of effective amounts of

dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol , more specifically, the present compositions comprise mixtures of about 3 to 70 weight percent dichlorotrifluoroethane, about 30 to 94.5 weight percent

1,1-dichloro-1-fluoroethane and about 0.1 to 5 weight percent methanol and/or ethanol . Even more specifically, the present compositions consist essentially of about 30 to 70 weight percent dichlorotrifluoroethane, about 25 to 70 weight percent 1,1-dichloro-1-fiuoroethane and about 1 to 5 weight percent methanol and/or ethanol . The constant-boiling, azeotrope-like compositions of the instant invention boil at about 30-32°C, at substantially atmospheric pressure (760mm Hg) . These

azeotrope or azeotrope-like compositions are more fully described in U.S. Patent No. 4,863,630, issued September 5, 1989 and U.S. Application Serial Nos. 07/297,366 filed January 17, 1989, and 07/297,467 filed January 17, 1989, all

incorporated herein by reference.

The more preferred constant-boiling azeotrope or azeotrope-like composition of the instant invention has the following composition: about 36 weight percent

1,1-dichloro-2,2,2-trifluoroethane, about 61 weight percent 1,1-dichloro-1-fluoroethane and about 3 weight percent

methanol . The constant-boiling azeotrope or azeotrope-like composition boils at about 30°C, at substantially atmospheric pressure (760mm Hg) .

A preferred constant-boiling azeotrope or

azeotrope-like composition of the instant invention is about 40 weight percent 1,1-dichloro-2,2,2-trifluoroethane, about 59 weight percent 1,1-dichloro-1-fluoroethane and about 1 weight percent ethanol . The constant-boiling azeotrope or

azeotrope-like composition boils at about 31°C, at

substantially atmospheric pressure.

The above constant-boiling azeotrope or azeotrope-like compositions are effective solvents for cleaning circuit boards. Such solvent compositions are characterized by desirable properties of relatively low boiling points, non-flanmability, relatively low toxicity and high solvency for flux and flux residues. The components also permit easy recovery and reuse without loss of their desirable

characteristics because of their azeotrope-like nature and relatively low boiling points.

While the azeotrope or azeotrope-like compositions of dichlorotrifluoroethane, 1,1-dichloro-1-fluoroethane with methanol and/or ethanol perform well in printed circuit board vapor defluxing-degreasing applications, it is recognized that in order to take practical advantage of the unique properties of these solvent compositions, certain other desirable properties should be imparted to the compositions,

particularly, if the solvent systems are to be used

commercially.

One such desirable property is storage stability. It is recognized that any material which is to be used

commercially must usually be inventoried. Such storage can be for short intervals or for longer periods of months or even years. Thus, for solvent compositions to be useful , they should be stabilized against any significant deleterious changes which may be brought about by oxidation, polymerization or component interactions. Such changes may result in solvent discoloration, the formation of undesirable by-products, such as chloride ions and acids and/or the formation of insoluble polymeric materials. It nas been found that the addition of an inhibitor package, in the aforementioned concentration ranges, will provide effective storage stabilization.

Another comnercially desirable characteristic to be imparted to the solvent system is stability during use. For example, as described above, in the vapor defluxing cleaning procedure, the circuit board to be cleaned is first passed through a sump which contains boiling

solvent, for removal of bulk rosin, including thermally degraded rosin. In this simp, the organic solvent is in contact with a heat source for a prolonged time. After passage through the first sump the circuit board is passed through a sump which contains freshly distilled solvent and finally through solvent vapor over a boiling sump, which provides a final rinse with a clean solvent which condenses on the circuit board. Thus, in use, the organic solvent may be subjected to constant heating either in maintaining boiling sumps or in vaporizing the solvent to provide freshly distilled solvent or vapor to condense on the circuit board for the final rinse. It is, therefore, highly desirable to minimize any change in the solvent system which can adversely affect the cleaning process or degrade the integrity of the solvent. As mentioned earlier, such changes may be due to oxidation, polymerization or interaction among the solvent system components.

For example, one such interaction which should be minimized is the interaction between the

hydrochlorofluorocarbons and the alcohols of the azeotope or azeotrope-like compositions which may generate acidic products and chloride ions. As indicated in an earlier patent (U.S. Patent No.3,960,746) the combination of chlorofluorocarbon and lower alcohols, particularly methanol, may attack reactive metals such as zinc and aluminim as well as certain aluminum alloys, which are often used as materials of circuit board construction. It has been found that nitromethane may be incorporated in the preseht solvent system in concentrations of about 0.1 and 0.8 weight percent and effectively retard this type of attack.

Diisopropylamine or 2,6-dimethylpiperidine

(concentration about 0.025 and 0.2 percent by weight), in the presence of 4-methoxyphenol (concentration about 0.002 and 0.016 weight percent) and either 1,2-propylene oxide or

1,2-butylene oxide (concentration about 0.05 and 0.4 weight percent) provides outstanding stability to the present solvent systems. All weight percentages are based on the weight of the of the dichlorotrifluoroethane, 1,1-dichloro-1-fluoroethane and methanol or ethanol azeotrope or azeotrope-like compositions.

As shown in the examples, the stabilizers used in the present solvent systems, in the combinations described, appear to stabilize the the solvent systems by working

interdependently. Higher stabilizer concentrations than those specified, could be employed; however, under normal

circimstances, higher concentrations do not generally provide additional inhibition advantage.

One of the stabilized azeotrope or azeotrope-like compositions of the present invention may contain about 30 to 70 weight percent dichlorotrifluoroethane, about 25 to 70 weight percent 1,1-dichloro-1-fluoroethane, about 1 to 5 weight percent methanol, about 0.1 to 0.8 weight percent of

nitromethane, about 0.05 to 0.4 weight percent of either 1,2-propylene oxide or 1,2-butylene oxide, about 0.025 to 0.2 weight percent of either diisopropylamine or

2,6-dimethylpiperidine and about 0.002 to 0.016 weight percent 4-methoxyphenol.

The above described stabilized composition of the present invention may contain about 36 weight percent

1,1-dichloro-2,2,2-trifluoroethane, about 61 weight percent 1,1-dichloro-1-fluoroethane, about 3 weight percent methanol, about 0.2 weight percent nitromethane, about 0.05 weight percent of either 1,2-propylene oxide or 1,2-butylene oxided about 0.05 weight percent of either diisopropylamine or

2,6-dimethylpiperidine and about 0.004 weight percent

4-methoxyphenol.

Another stabilized azeotrope or azeotrope-like composition of the present invention may contain about 30 to 70 weight percent dichlorotrifluoroethane, about 25 to 70 weight percent 1,1-dichloro-1-fluoroethane, about 1 to 5 weight percent ethanol , about 0.1 to 0.8 weight percent of

nitromethane, about 0.05 to 0.4 weight percent of either

1,2-propylene oxide or 1,2-butylene oxide, about 0.025 to 0.2 weight percent of either diisopropylamine or

2,6-dimethylpiperidine and about 0.002 to 0.016 weight percent 4-methoxyphenol .

The above described stabil ized composition of the present invention may contain about 40 weight percent

1,1,-dichloro-2,2,2-trifluoroethane, about 59 weight percent 1,1-dichloro-1-fluoroethane, about 1 weight percent ethanol , about 0.2 weight percent nitromethane, about 0.05 weight percent of either 1,2-propylene oxide or 1,2-butylene oxide, about 0.05 weight percent of either diisopropylamine or

2,6-dimethylpiperidine and about 0.004 weight percent

4-methoxyphenol .

The present invention thus provides stabilized azeotrope or azeotrope-like compositions of

dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol or ethanol , which can be stored for long periods periods of time, which will undergo little or no change during either prolonged storage or commercial use and which minimize both aluminum corrosion aid gel formation.

The methods of preparation of the inhibitors incorporated into the azeotropes or azeotrope-like compositions of this invention, namely of nitromethane, 1,2-butylene oxide, 1,2-propylene oxide, diisopropylamine, 2,6-dimethylpiperidine and 4-methoxyphenol are known in the art. The aforestated azeotropes or azeotrope-like

compositions have low ozone depletion potentials and are expected to decompose almost completely, prior to reaching the stratosphere.

The azeotropes or azeotrope-like compositions of the present invention permit easy recovery and reuse of the solvent from vapor defluxing and degreasing operations because of their azeotropic natures. As an example, the azeotropic mixtures of this invention can be used in cleaning processes such as described in U.S. Patent No.3,881,949, which is incorporated herein by reference.

The azeotrope or azeotrope-like compositions of the instant invention with the components of the inhibitor package can be prepared by any convenient method including mixing or combining the desired component amounts. A preferred method is to weigh the desired component amounts and thereafter combine them in an appropriate container.

EXAMPLES

Comparative seven day storage stability tests of solvent system combinations of about 33.0 weight percent dichlorotrifluoroethane, about 64.5 weight percent

1,1-dichloro-1-fluoroethane and about 2.5 weight percent methanol with various inhibitor combinations were carried out by refluxing 150 ml of the solvent combination in a series of 500 ml Pyrex flasks using a 90 percent water-saturated solvent. The flasks were connected to water-cooled condensers, on top of which were affixed "Drierite" desiccant tubes to exclude atmospheric moisture from the test systems. Additionally, stainless steel (SS-304) specimens were located at the refluxing solvent vapor/air interface in the condenser and coupled stainless steel (SS-304)/aluminim alloy (AL-7075) specimens were located in the boiling liquids. The 1,1-dichloro-1-fluoroethane used in these tests contained 500 parts per million by weight of vinylidine chloride, an impurity nomally found in the crude product.

However, in test no.1 (below) , only 15 ppm by weight of vinylidine chloride was used. The solvent inhibitor systems tested are described in the Table.

The following tests were performed on each individual test system subsequent to test exposures:

1. Chloride ion concentration increases were measured. The tested solvent was extracted with an equal volume of deionized water and analyzed for chloride ion concentration. The corrosion products on the metal specimens were removed carefully by sliding a knife over the metal surface, without removing the base metal. The metal scrapings were returned to the flask in which it had been tested originally. One hundred ml of 5 percent sulfuric acid was added to the flask in order to dissolve the corrosion products. This solution was analyzed for chloride ion. Net test chloride ion was calculated from the combined chloride ion concentration found after the test less the chloride ion background found in the original solvent.

Chloride ion increase generally represents loss of solvent system component stability. Stability loss is generally accompanied by increased acidity.

2. Corrosion rates were measured by rubbing the metal surfaces with ink and pencil erasers, brushing the surfaces, rinsing the specimens with 1,1,2-trichlorotrifluoroethane, deionized water and acetoie, drying for 24 hours over

"Drierite" desiccant and weighing the sample to 0.0001 gram. Metal specimen weight loss is expressed in mils/year. An aluminum (AL-7075) corrosion rate of 4 mils/year is considered acceptable.

3. Solvent appearances and the aluminim specimens

(AL-7075) were rated visually using the following criteria: APPEARANCES AND RATINGS

RATINGS ACCEPTABLE LIQUID ALUMINUM-7075 (*)

0 Yes NO CHANGE OR TRACE CHANGE

clear, colorless bright, shiny

No gel 1 Yes VERY, VERY SLIGHT BUT ACCEPTABLE CHANGES very slight very, very slight clear, colorless corrosion or black gel drops spot deposits on ca.

5 - 10 % of surface 2 Borderline VERY SLIGHT BORDERLINE CHANGES NOTED.

MAY OR MAY NOT BE ACCEPTABLE FOR

INTENDED USE

clear, slightly very slight corrosion darkened. Slight or black spot gel drops formed, deposits on ca.

10 - 20 % of surface 3 No SLIGHT, UNACCEPTABLE CHANGES NOTED moderate amount of slight spotting gel drops in the and corrosion

liquid of surface on ca.

50% of surface

(*) All reactivity occurred on the AL-7075 surface which interfaced with the SS-304 in the liquid. The SS-304 specimens were essentially unchanged throughout the tests.

Claims

I CLAIM:

1. A stabilized azeotrope or azeotrope-like composition comprising effective amou rts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabilizing amounts of nitromethane, a lower alkoxyphenol , an epoxide selected from the group consisting of 1,2-propylene oxide and 1,2-butylene oxide and an amine selected from the group consisting of diisopropylamine and 2,6-dimethyl-piperidine.

2. The stabilized azeotrope or azeotrope-like composition of Claim 1 having a boiling point of about 30-32°C, at substantially atmospheric pressure.

3. The composition of Claim 1 wherein said nitromethane is present in concentration from about 0.1 to about 0.8 weight percent based on the weight of the azeotrope or azeotrope-like composition.

4. The composition of Claim 3 wherein said nitromethane is present in concentration of about 0.2 weight percent based on the weight of the azeotrope or azeotrope-like composition.

5. The composition of Claim 1 wherein said al koxyphenol is present in concentrations from about 0.002 to about 0.016 weight percent based on the weight of the azeotrope or azeotrope-like composition.

6. The composition of Claim 5 wherein said alkoxyphenol is present in concentration of about 0.004 weight percent based on the weight of the azeotrope or azeotrope-like composition.

7. The composition of Claim 1 wherein said alkoxyphenol is 4-methoxyphenol .

8. The composition of Claim 1 wherein said epoxide is present in concentrations from about 0.05 to 0.4 weight percent based on the weight of the azeotrope or azeotrope-like composition.

9. The composition of Claim 8 wherein said epoxide is present in concentration of about 0.05 weight percent based on the weight of the azeotrope or azeotrope-like composition.

10. The composition of Claim 1 wherein said amine is present in concentrations from about 0.025 to 0.2 weight percent based on the weight of the azeotrope or azeotrope-like composition.

11. The composition of Claim 10 wherein said amine is present in concentration of about 0.05 weight percent based on the weight of the azeotrope or azeotrope-like composition.

12. The composition of Claim 1 wherein both 1,2-propylene oxide and diisipropylamine are present.

13. The composition of Claim 1 wherein both 1,2-propylene oxide and 2,6-dimethylpiperidine are present.

14. The composition of Claim 1 wherein both 1,2-butylene oxide and diisipropylamine are present.

15. The composition of Claim 1 wherein both 1,2-butylene oxide and 2,6-dimethylpiperidine are present.

16. The stabilized azeotrope or azeotrope-like

composition of Claim 1 wherein the azeotrope or azeotrope-like composition consists essentially of about 3 to 70 weight percent dichlorotrifluoroethane, about 25 to 94.9 weight percent 1, 1-dichloro-1-fluoroethane and about 0.1 to 5 weight percent methanol .

17. The stabilized azeotrope or azeotrope-like

composition of Claim 16 wherein the azeotrope or

azeotrope-liked composition consists essentially of about 30 to 70 weight percent dichlorotrifluoroethane, about 25 to 70 weight percent 1,1-dichloro-1-fluoroethane and about 1 to 5 weight percent methanol .

18. The stabil ized azeotrope or azeotrope-l ike composition of Claim 17 consists essentially of about 36 weight percent

1,1-dichloro-2,2,2-trifluoroethane, about 61 weight percent 1,1-dichloro-1-fluoroethane, about 3 weight percent methanol .

19. The stabilized azeotrope or azeotrope-like

composition of Claim 1 comprising an azeotrope or

azeotrope-like composition consisting essentially of about 3 to 70 weight percent dichlorptrifluoroethane, about 25 to 70 weight percent 1,1-dichloro-1-fluoroethane and about 1 to 5 weight percent ethanol .

20. The stabilized azeotrope or azeotrope-like

composition of Claim 19 comprising about 40 weight percent dichlorotrifluoroethane, about 59 weight percent

1,1-dichloro-1-fluoroethane and about 1 weight percent ethanol .

21. A stabilized azeotrope or azeotrope-like composition comprising effective amounts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabilizing amounts of 1,2-butylene oxide and/or 2,6-dimethylpiperidine.

22. A stabilized azeotrope or azeotrope-like composition comprising effective amounts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabilizing amounts of nitromethane and at least one compound selected from the group consisting of 1,2-propylene oxide, 1,2-butylene oxide, diisopropylamine and

2 , 6-dimethylpiperidine.

23. A stabilized azeotrope or azeotrope-like composition comprising effective amounts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabi l izing amounts of nitromethane, 1,2-propylene oxide and 1,2-butylene oxide.

24. A stabilized azeotrope or azeotrope-like composition comprising effective amounts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabilizing amounts of nitromethane, diisopropylamine and an epoxide selected from the group consisting of

1,2-propylene oxide and 1,2-butylene oxide.

25. A stabilized azeotrope or azeotrope-like composition comprising effective amour ts of dichlorotrifluoroethane and 1,1-dichloro-1-fluoroethane with methanol and/or ethanol plus effective stabilizing amounts of nitromethane, 4-methoxyphenol and an amine selected from the group consisting of

diisopropylamine and 2,6-eimethylpiperidine.