WO1991007523A1

WO1991007523A1 - AZEOTROPE-LIKE COMPOSITIONS OF 1,1-DICHLORO-1-FLUOROETHANE, DICHLOROTRIFLUOROETHANE, A MONO- OR DI-CHLORINATED C1, C2 or C3 ALKANE AND OPTIONALLY METHANOL

Info

Publication number: WO1991007523A1
Application number: PCT/US1990/004333
Authority: WO
Inventors: Ellen Louise Swan; Peter Brian Logsdon; Leonard Michael Stachura; Rajat Subhra Basu
Original assignee: AlliedSignal Inc
Current assignee: Honeywell International Inc
Priority date: 1989-11-13
Filing date: 1990-08-02
Publication date: 1991-05-30
Anticipated expiration: 1992-05-13
Also published as: IE902661A1; AU6299690A

Abstract

Stable azeotrope-like compositions comprising 1,1-dichloro-1-fluoroethane, dichlorotrifluoroethane, a mono- or di-chlorinated C1, C2 or C3 alkane and optionally methanol which are useful in a variety of industrial cleaning applications.

Description

AZEOTROPE-LIKE COMPOSITIONS OF 1,1-DICHLORO-l-FLUOROETHANE, DICHLOROTRIFLUOROETHANE, A MONO- OR DI- CHLORINATED C^ C₂ OR C- ALKANE AND

OPTIONALLY METHANOL

Field of the invention

0 This invention relates to azeotrope-like mixtures of 1,1-dichloro-l-fluoroethane, dichlorotri- fluoroethane, a mono- or di-chlorinated C,, C_ or C_ alkane and optionally methanol. These mixtures are useful in a variety of vapor degreasing, cold 5 cleaning and solvent cleaning applications including defluxing.

CROSS-REFERENCES TO RELATED APPLICATIONS

0 Co-pending, commonly assigned application Serial No.: 297,467, filed January 19, 1989, discloses azeotrope-like mixtures of 1,1-dichloro-l- fluoroethane, dichlorotrifluoroethane and methanol.

5 Issued, commonly assigned U.S. Patent

No.: 4,863,630, discloses azeotrope-like mixtures of 1,1-dichloro-l-fluoroethane, dichlorotrifluoroethane and ethanol.

_Q Co-pending commonly assigned application

Serial No.: 362,294, filed June 6, 1989, discloses azeotrope-like mixtures of 1,1-dichloro-l-fluoro¬ ethane and dichlorotrifluoroethane.

Issued, commonly assigned U.S. Patent No.: 5 4,842,764, discloses azeotrope-like mixtures of 1,1- dichloro-1-fluoroethane and methanol. Co-pending, commonly assigned application Serial No.: 423,993, filed October 19, 1989, discloses azeotrope-like mixtures of dichloro- trifluoroethane and methanol.

BACKGROUND OF THE INVENTION

Fluorocarbon based solvents have been used extensively for the degreasing and otherwise cleaning of solid surfaces, especially intricate parts and difficult to remove soils.

In its simplest form, vapor degreasing or solvent cleaning consists of exposing 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 contaminants. Final evaporation of solvent from the object leaves the object free of residue. This is contrasted with liquid solvents which leave deposits on the object after rinsing.

A vapor degreaser is used for difficult to remove soils where elevated temperature is necessary to improve the cleaning action of the solvent, or for large volume assembly line operations where the cleaning of metal parts and assemblies must be done efficiently. The conventional operation of a vapor degreaser consists of immersing the part to be cleaned in a sump of boiling solvent which removes the bulk of the soil, thereafter immersing the part in a sump containing freshly distilled solvent near room temperature, and finally exposing the part to solvent vapors over the boiling sump which condense on the cleaned part. In addition, the part can also be sprayed with distilled solvent before final rinsing. Vapor degreasers suitable in the above-described operations are well known in the art. For example, Sherliker et al. in U.S. Patent •- 3,085,918 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 0 number of solvents are used. In most cold cleaning applications the soiled part is either immersed in the fluid or wiped with cloths soaked in solvents and allowed to air dry.

Recently, nontoxic nonflammable fluorocarbon solvents like trichlorotrifluoroethane have been used extensively in degreasing applications and other solvent cleaning applications. Trichlorotrifluoro¬ ethane has been found to have satisfactory solvent power for greases, oils, waxes 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, etc.

The art has looked towards azeotropic compositions having fluorocarbon components bacause the fluorocarbon components contribute additionally desired characteristics, like polar functionality, increased solvency power, and stabilizers. Azeotropic 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. Therefore, unless the solvent composition is essentially constant boiling, fractionation will occur and undesirable solvent distribution may act to upset the cleaning and safety of processing. For example, preferential evaporation of the more volatile components of the solvent mixtures would result in mixtures with changed compositions which may have less desirable properties, such as lower solvency towards soils, less inertness towards metal, plastic or elastomer components, and increased flammability and toxicity.

The art is continually seeking new fluorocarbon based azeotropic mixtures which offer alternatives for new and special applications for vapor degreasing and other cleaning applications. Currently, fluorocarbon based azeotrope-like mixtures are of particular interest because they are considered to be stratospherically safe substitutes for presently used fully halogenated chlorofluoro- carbons. The latter have been implicated in causing environmental problems associated with the depletion of the earth's protective ozone layer. Mathematical models have substantiated that hydrochlorofluoro- carbons, like 1, 1-dichloro-l- fluoroethane (HCFC-141b) and dichlorotrifluoroethane (HCFC-123 or HCFC-123a) , have a much lower ozone depletion potential and global warming potential than the fully halogenated species.

Commonly assigned U.S. Patent 4,836,947 discloses azeotrope-like mixtures of 1, 1-dichloro- l-fluoroethane and ethanol. Commonly assigned U.S. Patent 4,842,764 discloses azeotrope-like mixtures of 1, 1-dichloro-l-fluoroethane and methanol. Commonly assigned U.S. Patent 4,863,630 discloses azeotrope- like mixtures of 1, 1-dichloro-l-fluoroethane; dichlorotrifluoroethane; and ethanol. Kokai Patent Publication 103,686, published April 20, 1989, discloses an azeotropic mixture of 55 to 80 weight percent dichlorotrifluoroethane and 20 to 45 weight percent 1,1-dichloro-l-fluoroethane. Kokai Patent Publication 138,300, published May 31, 1989, discloses a flux cleaning agent of an azeotrope of 67 weight percent 1,l-dichloro-2,2,2-trifluoro¬ ethane and 33 weight percent 1,1-dichloro-l-fluoro¬ ethane, plus hydrocarbons, alcohols, ketones, and chlorinated hydrocarbons.

Kokai Patent Publication 139,104, published May 31, 1989, discloses a solvent of an azeotropic mixture of 67 weight percent 1,l-dichloro-2,2,2-tri- fluoroethane and 33 weight percent 1,1-dichloro-l- fluoroethane, plus hydrocarbons, alcohols, ketones, chlorinated hydrocarbons, and surfactants. Kokai Patent Publication 139,861, published June 1, 1989, discloses a dry-cleaning agent of 67 weight percent 1,l-dichloro-2,2,2-trifluoroethane and 33 weight percent 1,1-dichloro-l-fluoroethane, plus hydrocarbons, alcohols, ketones, chlorinated hydrocarbons, and surfactants.

Kokai Patent Publication 136,981, published May 30, 1989, discloses a degreasing cleaning agent of an azeotropic mixture of 67 weight percent 1,l-dichloro-2,2,2-trifluoroethane and 33 weight percent 1,1-dichloro-l-fluoroethane, plus hydrocarbons, alcohols, ketones, chlorinated hydrocarbons, and esters. Kokai Patent Publication 136,982, published May 30, 1989, discloses a buff-grinding cleaning agent of an azeotropic mixture of 67 weight percent 1,l-dichloro-2,2,2-trifluoro¬ ethane and 33 weight percent 1,1-dichloro-l-fluoro¬ ethane, plus hydrocarbons, alcohols, ketones, chlorinated hydrocarbons, and esters. Accordingly, it is an object of the invention to provide novel environmentally acceptable azeotropic compositions which are useful in a variety of industrial cleaning applications.

It is another object of the invention to provide azeotrope-like compositions which are liquid at room temperature and which will not fractionate under conditions of use.

Other objects and advantages of the invention will become apparent from the following description.

SUMMARY OF THE INVENTION

The invention relates to novel azeotrope-like compositions which are useful in a variety of industrial cleaning applications. Specifically, the invention relates to compositions based on 1,1- dichloro-1-fluoroethane and dichlorotrifluoroethane which are essentially constant boiling, environmentally acceptable, nonfractionating, and which remain liquid at room temperature.

DETAILED DESCRIPTION QF THE INVENTION

In accordance with the invention, novel azeotrope-like compositions have been discovered comprising 1,1-dichloro-l-fluoroethane (HCFC-141b), dichlorotrifluoroethane, a mono- or di-chlorinated C, , C_ or C_ alkane and optionally methanol. Dichlorotrifluoroethane exists in three isomeric forms, 1,l-dichloro-2,2,2-trifluoroethane (HCFC-123), l,2-dichloro-l,2,2-trifluoroethane (HCFC-123a), and l,l-dichloro-l,2,2-trifluoroethane (HCFC-123b) . For purposes of this invention, dichlorotrifluoroethane will refer only to the HCFC-123 and HCFC-123a isomers. Each of these isomers exhibits the properties of the invention. Hence either isomer may be used as well as mixtures of the isomers in any proportion. The preferred dichlorotrifluoroethane isomer is HCFC-123 and preferably, "commercial HCFC-123." "Commercial HCFC-123" is available as "pure" HCFC-123 containing about 90 to about 95 weight percent of HCFC-123, about 5 to about 10 weight percent of HCFC-123a, and impurities such as trichloromonofluoromethane, trichlorotrifluoroethane, and methylene chloride which, due to their presence in insignificant amounts, have no deleterious effects on the properties of the azeotrope-like compositions. "Commercial HCFC-123" is also available as "ultra-pure" HCFC-123 which contains about 95 to about 99.5 weight percent of HCFC-123, about 0.5 to about 5 weight percent of HCFC-123a, and impurities as listed above.

When the chlorinated alkane component is a mono-chlorinated propane, either isomer or a mixture of the isomers may be used in any proportion.

HCFC-141b has a low ozone depletion potential. HCFC-123 has a still lower ozone depletion potential. when these materials are combined in effective amounts with the chlorinated alkane component of the invention, a very low ozone depleting composition results. HCFC-141b and HCFC-123 also suppress the flammablility of the chlorinated alkane component when used in effective amounts. Methanol and the chlorinated alkane component exhibit superior solvent properties. Hence, when these materials, i.e., HCFC-123, HCFC-141b, the chlorinated alkane component, and optionally methanol are combined in effective amounts, novel, environmentally acceptable, nonflammable, azeotrope- like cleaning solvents result.

When 1-chloropropane is the chlorinated alkane component, the azeotrope-like compositions of the invention comprise from about 25 to about 99 weight percent HCFC-141b, from about 1 to about 72 weight 0 percent dichlorotrifluoroethane, and from about 0.1 to about 3 weight percent 1-chloropropane and boil at about 31.9°C at 760 mm Hg.

In a preferred embodiment of the invention ■,c using 1-chloropropane, the azeotrope-like compositions of the invention comprise from about 63 to about 99 weight percent HCFC-141b, from about 1 to about 35 weight percent dichlorotrifluoroethane, and from about 0.1 to about 2 weight percent 1-chloropropane and boil at about 31.9°C at 760 mm Hg,

20

In a more preferred embodiment of the invention including 1-chloropropane, the azeotrope- like compositions comprise from about 66 to about 99

25 weight percent HCFC-141b, from about 1 to about 32 weight percent dichlorotrifluoroethane and from about 0.1 to about 2 weight percent 1-chloropropane and which boil at about 31.9°C at 760 mm Hg.

In the most preferred embodiment of the

30 invention containing 1-chloropropane, the azeotrope- like compositions comprise from about 67 to about 99 weight percent HCFC-141b, from about 1 to about 32 weight percent dichlorotrifluoroethane and from about 0.1 to about 1 weight percent of 1-chloroproρane and

35 which boil at about 31.9°C at 760 mm Hg. When 2-chloropropane is the chlorinated alkane component, the azeotrope-like compositions of the invention comprise from about 25 to about 99 weight percent HCFC-141b, from about 1 to about 70 weight percent dichlorotrifluoroethane, and from about 0.25 to about 5 weight percent 2-chloropropane and boil at about 31.9°C at 760 mm Hg.

10 In a preferred embodiment of the invention using 2-chloropropane, the azeotrope-like compositions of the invention comprise from about 60 to about 99 weight percent HCFC-141b, from about 1 to about 35 weight percent dichlorotrifluoroethane, and ,_ς from about 0.1 to about 5 weight percent 2-chloro¬ propane and boil at about 31.9°C at 760 mm Hg.

In a more preferred embodiment of the invention including 2-chloropropane, the azeotrope-

20 like compositions comprise from about 65 to about 99 weight percent HCFC-141b, from about 1 to about 31 weight percent dichlorotrifluoroethane and from about 0.1 to about 4 weight percent 2-chloropropane and boil at about 31.9°C at 760 mm Hg. 5

In the most preferred embodiment of the invention containing 2-chloropropane, the azeotrope- like compositions of the invention comprise from about 70 to about 87 weight percent HCFC-141b, from about 12 to about 28 weight percent dichlorotrifluoro¬ 0 ethane, and from about 0.4 to about 2 weight percent 2-chloropropane and boil at about 31.9°C at 760 mm Hg,

When 1,1-dichloroethane is the chlorinated alkane component, the azeotrope-like compositions of 5 the invention comprise from about 25 to about 99 weight percent HCFC-141b, from about 1 to about 72 weight percent dichlorotrifluoroethane, and from about 0.1 to about 3 weight percent 1,1- dichloroethane and boil at about 31.4°C at 760 mm Hg.

In a preferred embodiment of the invention using 1, 1-dichloroethane, the azeotrope-like compositions of the invention comprise from about 63 to about 99 weight percent HCFC-141b, from about 1 to about 35 weight percent dichlorotrifluoroethane, and from about 0.1 to about 2 weight percent 1,1-dichloro¬ ethane and boil at about 31.4°C at 760 mm Hg.

In a more preferred embodiment including 1, 1-dichloroethane, the azeotrope-like compositions of the invention comprise from about 68 to about 98 weight percent HCFC-141b, from about 2 to about 30 weight percent dichlorotrifluoroethane, and from about 0.1 to about 2 weight percent 1,1-dichloro¬ ethane and boil at about 31.4°C at 760 mm Hg.

In the most preferred embodiment of the invention containing 1, 1-dichloroethane, the azeotrope-like compositions of the invention comprise from about 69 to about 97 weight percent HCFC-141b, from about 3 to about 30 weight percent dichloro¬ trifluoroethane, and from about 0.1 to about 1 weight percent 1, 1-dichloroethane and boil at about 31.4°C at 760 mm Hg.

When 2-chloroproρane is the chlorinated alkane component of the invention and methanol is added, the azeotrope-like compositions comprise from about 25 to about 98 weight percent HCFC-141b, from about 1 to about 67 weight percent dichlorotrifluoroethane, from about 0.5 to about 4 weight percent 2-chloropropane and from about 1 to about 4 weight percent methanol. In a preferred embodiment of the invention using 2-chloropropane and methanol, the azeotrope- like compositions of the invention comprise from c about 57 to about 97 weight percent of HCFC-141b, from about 1 to about 35 weight percent of dichlorotrifluoroethane, from about 0.5 to about 4 weight percent of 2-chloropropane and from about 1 to about 4 weight percent methanol and boil at about 0 30.9°C at 760 mm Hg.

In a more preferred embodiment of the invention containing 2-chloropropane and methanol, the azeotrope-like compositions of the invention 5 comprise from about 62 to about 95 weight percent of HCFC-141b, from about 2 to about 31 weight percent of dichlorotrifluoroethane, from about 1 to about 3 weight percent of 2-chloropropane, and from about 2 to about 4 weight percent methanol and boil at about 30.9°C at 760 mm Hg.

In the most preferred embodiment of the invention containing 2-chloropropane and methanol, the azeotrope-like compositions of the invention comprise from about 63 to about 92 weight percent HCFC-141b, from about 5 to about 30 weight percent of dichlorotrifluoroethane, from about 2 to about 4 weight percent of methanol, and from about 1 to about 3 weight percent of 2-chloropropane and boil at about 30.9°C at 760 mm Hg.

When 1-chloropropane is the chlorinated alkane component of the invention and methanol is added, the azeotrope-like compositions comprise from about 25 to about 98 weight percent HCFC-141b, from about 1 to about 69 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1-chloropropane and from about 1 to about 4 weight ppeerrcceenntt imrnethanol and boil at about 30.9 C at 760 mm Hg

In a preferred embodiment of the invention using 1-chloropropane and methanol, the azeotrope- like compositions of the invention comprise from about 59 to about 98 weight percent HCFC-141b, from about 1 to about 35 weight percent dichlorotri- fluoroethane, from about 0.1 to about 2 weight percent 1-chloropropane, and from about 1 to about 4 weight percent methanol and boil at about 30.9°C at 760 mm Hg .

In a more preferred embodiment of the invention utilizing 1-chloropropane and methanol, the azeotrope-like compositions comprise from about 63 to about 96 weight percent HCFC-141b, from about 2 to about 31 weight percent dichlorotrifluoroethane, from about 0.2 to about 2 weight percent 1-chloropropane and from about 2 to about 4 weight percent methanol and boil at about 30.9°C at 760 mm Hg.

In the most preferred embodiment of the invention containing 1-chloropropane and methanol, the azeotrope-like compositions comprise from about 65 to about 92 weight percent HCFC-141b, from about 5.0 to about 30.0 weight percent dichlorotri- fluoroethane, from about 0.2 to about 1 weight percent 1-chloropropane, and from about 2 to about 4 weight percent methanol and boil at about 30.9°C at 760 mm Hg.

When 1, 1-dichloroethane is the chlorinated alkane component and methanol is added, the azeotrope-like compositions of the invention comprise from about 25 to about 98 weight percent HCFC-141b, from about 1 to about 66 weight percent dichlorotri- fluoroethane, from about 0.1 to about 3 weight c percent 1,1-dichloroethane and from about 1 to about 6 weight percent methanol and boil at about 29.8°C at 760 mm Hg.

In a preferred embodiment of the invention 0 using 1,1-dichloroethane and methanol, the azeotrope- like compositions of the invention comprise from about 55 to about 98 weight percent HCFC-141b, from about 1 to about 37 weight percent dichlorotri- fluoroethane, from about 0.1 to about 2 weight .. percent 1,1-dichloroethane and from about 1 to about

6 weight percent methanol and boil at about 29.8°C at 760 mm Hg.

In a more preferred embodiment of the invention using 1,1-dichloroethane and methanol, the azeotrope-like compositions of the invention comprise from about 59 to about 96 weight percent HCFC-141b, from about 2 to about 33 weight percent dichlorotri- fluoroethane, from about 0.1 to about 2 weight percent 1,1-dichloroethane and from about 2 to about 6 weight percent methanol and boil at about 29.8°C at 760 mm Hg.

In the most preferred embodiment of the invention containing 1,1-dichloroethane and methanol, the azeotrope-like compositions comprise from about 62 to about 93 weight percent HCFC-141b, from about 5 to about 30 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1,1-dichloro¬ ethane and from about 2 to about 6 weight percent methanol and boil at about 29.8°C at 760 mm Hg. When dichloromethane is the chlorinated alkane component and the dichlorotrifluoroethane used is 1,l-dichloro-2,2,2-trifluoroethane, the azeotrope- 5 like compositions of the invention preferably comprise 1,1-dichloro-l-fluoroethane; 1,1-dichloro- 2,2,2-trifluoroethane; and dichloromethane and boil at about 31.8°C ± about 0.4°C at 760 mm Hg (101 kPa) .

o ^In a preferred embodiment utilizing dichloromethane and 1,l-dichloro-2,2,2-tri- fluoroethane, the azeotrope-like compositions of the invention comprise from about 55 to about 98.5 weight percent of 1,1-dichloro-l-fluoroethane; from about 1 _jr to about 41 weight percent of 1,l-dichloro-2,2,2- trifluoroethane; and from about 0.5 to about 4 weight percent of dichloromethane and boil at about 31.8°C at 760 mm Hg (101 kPa) .

20 In a more preferred embodiment utilizing dichloromethane and 1,l-dichloro-2,2,2-trifluoro¬ ethane, the azeotrope-like compositions of the invention comprise from about 62 to about 98.5 weight percent of 1,1-dichloro-l-fluoroethane; from about 1 ₂_ to about 35 weight percent of 1,l-dichloro-2,2,2- trifluoroethane; and from about 0.5 to about 3 weight percent of dichloromethane.

In a most preferred embodiment utilizing dichloromethane and 1,l-dichloro-2,2,2-trifluoro¬

30 ethane, the azeotrope-like compositions of the invention comprise from about 65.5 to about 98.5 weight percent of 1,1-dichloro-l-fluoroethane; from about 1 to about 32 weight percent of 1,l-dichloro- 2,2,2-trifluoroethane; and from about 0.5 to about

35 2.5 weight percent of dichloromethane. Because the boiling point of 1, l-dichloro- 2,2,2-trifluoroethane is 27.8°C and the boiling point of 1,2-dichloro-l,1,2-trifluoroethane is 29.9°C, it is believed that azeotrope-like compositions of 1,2-dichloro-l,1,2-trifluoroethane; 1,1-dichloro-l- fluoroethane; and dichloromethane would form. It should be understood that the aforementioned compositional ranges for azeotrope-like compositions of 1,1-dichloro-l-fluoroethane; 1,l-dichloro-2,2,2- trifluoroethane; and dichloromethane also apply to azeotrope-like compositions of 1,1-dichloro-l- fluoroethane; 1,2-dichloro-l,1,2-trifluoroethane; and dichloromethane.

Because the boiling point of 1,l-dichloro- 2,2,2-trifluoroethane is so close to the boiling point of 1,2-dichloro-l,1,2-trifluoroethane, it is also believed that azeotrope-like compositions of 1,1-dichloro-l-fluoroethane; a mixture of 1,1- dichloro-2,2,2-trifluoroethane and 1,2-dichloro- 1,1,2-trifluoroethane; and dichloromethane would form.

When a mixture of 1,l-dichloro-2,2,2-trifluoro¬ ethane and 1,2-dichloro-l,1,2-trifluoroethane are employed with dichloromethane preferably, the azeotrope-like compositions of the invention comprise from about 55 to about 98.5 weight percent of 1,1-dichloro-l-fluoroethane; from about 1 to about 21 weight percent of 1,l-dichloro2,2,2-trifluoroethane; from about 1 to about 20 weight percent of 1,2-dichloro-l,1,2-trifluoroethane; and from about 0.5 to about 4 weight percent of dichloromethane.

In a more preferred embodiment utilizing dichloromethane and a mixture of 1,l-dichloro-2,2,2- trifluoromethane and 1,2-dichloro-l,1,2-trifluoro- methane, the azeotrope-like compositions comprise from about 62 to about 98.5 weight percent of 1,1-dichloro-l-fluoroethane; from about 1 to about 21 ₅ weight percent of 1,l-dichloro-2,2,2-trifluoroethane; from about 1 to about 20 weight percent of 1,2-dichloro-l,1,2-trifluoroethane; and from about 0.5 to about 3 weight percent of dichloromethane.

0 In a most preferred embodiment utilizing dichloromethane and a mixture of 1,l-dichloro- 2,2,2-trifluoromethane and 1,2-dichloro-l,1,2- trifluoroethane, the azeotrope-like compositions of the invention comprise from about 65.5 to about 98.5 , _c weight percent of 1,1-dichloro-l-fluoroethane; from about 1 to about 21 weight percent of 1,l-dichloro- 2,2,2-trifluoroethane; from about 1 to about 20 weight percent of 1,2-dichloro-l,1,2-trifluoroethane; and from about 0.5 to about 2.5 weight percent of dichloromethane.

20

The compositions of the invention containing a mixture of HCFC-123 and HCFC-123a behave like azeotropic compositions because the separate ternary

25 azeotrope-like compositions containing HCFC-123 and HCFC-123a have boiling points so close to one another that they are indistinguishable for practical purposes.

It is known in the art that the use of more

30 active solvents, like lower alkanols in combination with certain halocarbons such as trichlorotrifluoro¬ ethane, may have the undesirable result of attacking reactive metals such as zinc and aluminum, as well as certain aluminum alloys and chromate coatings such as

35 are commonly employed in circuit board assemblies. The art has recognized that certain stabilizers, such as nitromethane, are effective in preventing metal attack by chlorofluorocarbon mixtures with such alkanols. Other candidate stabilizers for this 5 purpose, such as disclosed in the literature, are secondary and tertiary amines, olefins and cycloolefins, alkylene oxides, sulfoxides, sulfones, nitrites and nitriles, and acetylenic alcohols or ethers. It is contemplated that such stabilizers as JLO well as other additives may be combined with the azeotrope-like compositions of this invention.

The precise or true azeotrope compositions have not been determined but have been ascertained to 5 be within the indicated ranges. Regardless of where the true azeotropes lie, all compositions within the indicated ranges, as well as certain compositions outside the indicated ranges, are azeotrope-like, as defined more particularly below. 0

It has been found that these azeotrope-like compositions are on the whole nonflammable liquids, i.e., exhibit no flash point when tested by the Tag Open Cup test method - ASTM D 1310-86. 5

From fundamental 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 0 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 mixture cannot be separated during distillation, and therefore are useful in vapor phase solvent cleaning as described above. 5 For the purpose of this discussion, by azeotrope-like composition is intended to mean that the composition behaves like a true azeotrope in terms of its constant boiling characteristics or tendency not to fractionate upon boiling or evaporation. Such compositions may or may not be a true azeotrope. Thus, in such compositions, the composition of the vapor formed during boiling or evaporation is identical or substantially identical to the original liquid composition. Hence, during boiling or evaporation, the liquid composition, if it changes at all, changes only minimally. This is contrasted with non-azeotrope-like compositions in which the liquid composition changes substantially during boiling or evaporation.

Thus, one way to determine whether a candidate mixture 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 expected to separate the mixture into its components. If the mixture is non-azeotropic or non-azeotrope-like, the mixture will fractionate, i.e. separate into its various components with the lowest boiling component distilling off first, etc.

If the mixture is azeotrope-like, some finite amount of a first distillation cut will be obtained which contains all of the mixture components and which is constant boiling or behaves as a single substance. This phenomenon cannot occur if the mixture is not azeotrope-like i.e., it is not part of an azeotropic system. If the degree of fractionation of the candidate mixture is unduly great, then a composition closer to the true azeotrope must be selected to minimize fractionation. 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 characteristic of azeotrope-like compositions is that there is a range of compositions containing the same components in varying proportions which are azeotrope-

10 like. All such compositions are intended to be covered by the term azeotrope-like as used herein. As an example, it is well known that at different pressures, the composition of a given azeotrope will vary at least slightly as will the boiling point of •_jc the composition. Thus, an azeotrope of A and B represents a unique type of relationship but with a variable composition depending on temperature and/or pressure. Accordingly, another way of defining azeotrope-like within the meaning of this invention

20 is to state that such mixtures boil within about ± 0.6°C (at 760 mm Hg) of the boiling point of the most preferred compositions disclosed herein. As is readily understood by persons skilled in the art, the boiling point of the azeotrope will vary with the 5 pressure.

In the process embodiment of the invention, the azeotrope-like compositions of the invention may be used to clean solid surfaces by treating the surfaces with said compositions in any manner well 0 known in the art such as by dipping or spraying or use of conventional degreasing apparatus.

The 1,1-dichloro-l-fluoroethane, dichlorotri- fluoroethane, methanol, 1,1-dichloroethane, 5 1-chloroproρane, 2-chloropropane and dichloromethane components of the invention are known materials. Preferably they should be used in sufficiently high purity so as to avoid the introduction of adverse influences upon the solvency properties or constant boiling properties of the system.

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 the essential components described herein.

The present invention is more fully illustrated by the following non-limiting Examples.

EXAMPLES 1-3

This set of examples further confirms the existence of the azeotropes between HCFC-141b,

HCFC-123, and 2-chloropropane via the method of distillation. They also illustrate 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 these examples. For Examples 1-3 the distillation column waε charged with approximately 350 grams of mixture of HCFC-141b, HCFC-123 and 2-chloroρropane which were heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3:1 was employed for this particular distillation. Approximately 50 percent of the original charges were collected in four approximately equivalent overhead fractions. The compositions of these fractions were analyzed using gas chromatrography. Table I shows the compositions of the starting materials. The averages of the distillate fractions and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixtures are azeotrope-like.

TABLE I

STARTING MATERIAL (WT. %)

EXAMPLE HCFC-1 1b HCFC-123 2-CHLOROPROPANE

1 87.48 10.37 2.15 2 72.92 25.04 2.05 3 89.18 10.29 0.53

DISTILLATE FRACTIONS (WT. %)

2-CHLOROPROPANE

1.84 1.57

0.44

Examples 1-3 illustrate that HCFC-141b, HCFC-123 and 2-chloropropane form a constant boiling mixture. EXAMPLES 4-6

The azeotropic properties of HCFC-141b, HCFC-123a and 2-chloropropane are studied by repeating the experiment outlined in Examples 1-3. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a, and 2-chloropropane form a constant boiling mixture.

EXAMPLES 7-9

The azeotropic properties of HCFC-141b, a mixture of HCFC-123 and 123a, and 2-chloropropane are studied by repeating the experiment outlined in

Examples 1-3. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123 and 123a and 2-chloropropane form a constant boiling mixture-

EXAMPLES 10-13

This set of examples further confirms the existence of azeotropes between HCFC-141b, HCFC-123 and 1-chloropropane via the method of distillation. They also illustrate that these mixtures do not fractionate during distillation.

Examples 10-13 were performed under the same conditions outlined in Examples 1-3 above.

Examples 10-13 illustrate that HCFC-141b, HCFC-123 and 1-chloropropane form a constant boiling mixture. EXA.-MPLES 14-17

The azeotropic properties of HCFC-141b, ₅ HCFC-123a and 1-chloropropane are studied by repeating the experiment outlined in Examples 1-3 above. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a, and 1-chloropropane form a constant boiling mixture. 0

EXAMPLES 18-21

The azeotropic properties of HCFC-141b, a mixture of HCFC-123 and 123a, and 1-chloropropane are •_jc studied by repeating the experiment outlined in Examples 1-3 above. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123/123a, and 1-chloropropane form a constant boiling mixture.

20

EXAMPLE 22

The azeotropic properties of HCFC-141b, HCFC-123 and 1,1-dichloroethane were studied by repeating the

25 experiment outlined in Examples 1-3 above except that the reflux ratio in the distillation was kept at 5:1.

TABLE III

STARTING MATERIAL (WT.%)

30

1-1,-DI- CHLORO- EXAMPLE HCFC-141b HCFC-123 ETHANE

22 73.81 25.15 1.03

35 DISTILLATE FRACTION (WT. %)

1-1,-DI-

CHLORO-

EXAMPLE HCFC-1 1b HCFC-123 ETHANE

22 68.51 30.35 0.14

BOILING POINT BOILING BAROMETRIC CORRECTED TO EXAMPLE POINT CC) PRESSURE (mm Hα) 760 mm Hα(°C)

22 31.1 747.0 31.4

Example 22 illustrates that HCFC-141b, HCFC-123 and 1,1-dichloroethane form a constant boiling mixture

EXAMPLE 23

The azeotropic properties of HCFC-141b, HCFC-123a and 1,1-dichloroethane are studied by repeating the experiment outlined in Examples 1-3 above. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a and 1,1-dichloroethane form a constant boiling mixture.

EXAMPLE 2

The azeotropic properties of HCFC-141b, a mixture of HCFC-123/123a, and 1,1-dichloroethane are studied by repeating the experiment outlined in Examples 1-3 above. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123/123a and 1,1-dichloroethane form a constant boiling mixture. EXAJIPLES 25-27

This set of examples further confirms the existence of the azeotropes between 1,1-dichloro-l- fluoroethane, dichlorotrifluoroethane, 1-chloro¬ propane, and methanol via the method of distillation. They also illustrate the essentially constant boiling character of the mixture, i.e., non-fractionating

10 during distillation.

A 5-plate Oldershaw distillation column with a cold water condensed automatic liquid dividing head was used for these examples. For Examples 25-27 the -,_£- distillation column was charged with approximately 350 grams of a mixture of HCFC-141b, HCFC-123, 1-chloro¬ propane, and methanol which were heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3:1 was employed for this particular distillation. Approximately 50 percent of the

20 original charges were collected in four similar-sized overhead fractions. The compositions of these fractions were analyzed using gas chromatrography. Tables I & II show the compositions of the starting materials. The averages of the distillate fractions

25 and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixtures are azeotropic.

30

35

Examples 25-27 illustrate that HCFC-141b, HCFC-123, 1-chloropropane and methanol form a constant boiling mixture.

EXAMPLES 28-30

The azeotropic properties of HCFC-141b, HCFC-123a, 1-chloroρropane and methanol are studied by repeating the experiment outlined in Examples 25-27. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a, 1-chloropropane and methanol form a constant boiling mixture.

EXAMPLES 31-33

The azeotropic properties of HCFC-141b, a mixture of HCFC-123 and 123a, 1-chloropropane, and methanol are studied by repeating the experiment outlined in Examples 25-27. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123 and 123a, 1-chloropropane, and methanol form a constant boiling mixture.

EXAMPLES 34-36

This next set of examples further confirms the existence of azeotropes between 1,1-dichloro-l- fluoroethane, dichlorotrifluoroethane, methanol and 2-chloroproρane via the method of distillation. They also illustrate that these mixtures do not fractionate during distillation.

Examples 34-36 were performed under the same conditions outlined in Examples 25-27 above.

DISTILLA

Examples 34-36 illustrate that HCFC-141b, HCFC-123, 2-chloropropane and methanol form a constant boiling mixture.

EXAMPLES 37-39

The azeotropic properties of HCFC-141b, HCFC-

123a, 2-chloropropane and methanol are studied by repeating the experiment outlined in Examples 25-27. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a, methanol and 2-chloropropane form a constant boiling mixture.

EXAMPLES 40-42

The azeotropic properties of HCFC-141b, a mixture of HCFC-123 and 123a, 2-chloropropane and methanol are studied by repeating the experiment outlined in Examples 25-27. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123 and 123a, methanol, and 2-chloropropane form a constant boiling mixture.

EXAMPLES 43-45

This set of examples further confirms the existence of azeotropes between 1,1-dichloro-l-fluoro¬ ethane, dichlorotrifluoroethane, methanol and 1,1-di¬ chloroethane via the method of distillation.

Examples 43-45 were performed under the same conditions outlined in Examples 25-27 above except that the reflux ratio in the distillation was kept at 5:1.

TABLE VI

STARTING MATERIAL (WT. %)

DISTILLATE FRACTION (WT. %)

Examples 43-45 illustrate that HCFC-141b, HCFC-123, 1,1-dichloroethane and methanol form a constant boiling mixture.

EXAMPLES 46-48

The azeotropic properties of HCFC-141b, HCFC-123a, 1,1-dichloroethane and methanol are studied by repeating the experiment outlined in Examples 25-27 above. Th*³ results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, HCFC-123a, methanol, and 1,1-dichloroethane form a constant boiling mixture.

EXAMPLES 49-51

The azeotropic properties of HCFC-141b, a mixture of HCFC-123/123a, 1,1-dichloroethane and methanol are studied by repeating the experiment outlined in Examples 25-27 above. The results obtained are substantially the same as those for HCFC-123, i.e., HCFC-141b, a mixture of HCFC-123/123a, methanol and 1-1-dichloroethane form a constant boiling mixture.

EXAMPLES 52-53

These examples confirm the existence of constant-boiling or azeotrope-like compositions of 1,1-dichloro-l-fluoroethane; 1,l-dichloro-2,2,2- trifluoroethane; and dichloromethane via 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 these examples. For each Example, the distillation column was charged with HCFC-141b, commercially available ultra-pure HCFC-123,- and dichloromethane in the amounts indicated in Table I below for the starting material. Each composition was heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3:1 was employed for these particular distillations. Approximately 50 percent of the original charges were collected in four similar-sized overhead fractions. The compositions of these fractions were analyzed using gas chromatography. The averages of the distillate fractions and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixtures are constant-boiling or azeotrope-like.

TABLE VII

Starting Material (wt. %)

Example HCFC-141b HCFC-123 Dichloromethan

52 88 . 90 9 . 99 1.11 53 74 . 34 24 . 63 1.03

Distillate Compositions (wt. %)

Example HCFC-141b HCFC-123 Dichloromethan 52 87.97 11.08 0.96 53 71.74 27.55 0.97

Mean 31.8 + 0.4

From the above examples, it is readily apparent that additional constant-boiling or essentially constant-boiling 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 ranges which are constant-boiling. Anyone skilled in the art can readily ascertain other constant-boiling or essentially constant-boiling mixtures containing the same components.

EXAMPLE 54

Example 1 is repeated except that 1,2-dichloro- 1,1,2-trifluoroethane is used instead of 1,l-dichloro- 2,2,2-trifluoroethane.

EXAMPLE 55

Example 1 is repeated except that a mixture of 1,l-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-l,1,2- trifluoroethane is used instead of 1,l-dichloro-2,2,2- trifluoroethane.

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.

Claims

What is claimed is:

1. Azeotrope-like compositions comprising 1,1-dichloro-l-fluoroethane, dichlorotrifluoroethane, and a mono- or di-chlorinated C,, C-, or C_ alkane selected from the group consisting of 1-chloropropane, 2-chloropropane, 1,1-dichloroethane and dichloromethane and optionally methanol wherein said compositions boil at about 31.0°C ± about 1.5°C at 760 mm Hg.

2. Azeotrope-like compositions comprising effective amounts of 1,1-dichloro-l-fluoroethane, dichlorotrifluoroethane, a mono- or di-chlorinated C- , C_ or C₃ alkane selected from the group consisting of 1-chloropropane, 2-chloropropane,

1,1-dichloroethane and dichloromethane and optionally methanol wherein said compositions boil at about 31.0°C + about 1.5°C at 760 mm Hg.

3. Azeotrope-like compositions consisting essentially of 1,1-dichloro-l-fluoroethane, dichloro¬ trifluoroethane, a mono- or di-chlorinated C, , C_ or C-. alkane selected from the group consisting of 1-chloropropane, 2-chloroproρane, 1,1-dichloro¬ ethane and dichloromethane and optionally methanol, wherein said compositions boil at about 31.0°C ± about 1.5°C at 760 mm Hg.

4. Azeotrope-like compositions consisting essentially of from about 25 to about 99 weight percent 1,1-dichloro-l-fluoroethane, from about 1 to about 72 weight percent dichlorotrifluoroethane, and from about 0.1 to about 3 weight percent 1-chloropropane which boil at about 31.9°C at 760 mm Hg.

5. The azeotrope-like compositions of claim 4 wherein said compositions consist essentially of from about 63 to about 99 weight percent 1, 1-dichloro-l- fluoroethane, from about 1 to about 35 weight percent dichlorotrifluoroethane, and from about 0.1 to about 2 weight percent 1-chloropropane.

6. The azeotrope-like compositions of claim 4 wherein said compositions consist essentially of from about 66 to about 99 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 32 weight percent dichlorotrifluoroethane, and from about 1 to about 2 weight percent 1-chloropropane.

7. The azeotrope-like compositions of claim 4 wherein said compositions consist essentially of from about 67 to about 99 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 32 weight percent dichlorotrifluoroethane, and from about 0.1 to about 1.0 weight percent 1-chloropropane.

8. Azeotrope-like compositions consisting essentially of from about 25 to about 99 weight percent 1,1-dichloro-l-fluoroethane, from about 1 to about 70 weight percent dichlorotrifluoroethane, and from about 0.25 to about 5 weight percent 2-chloropropane which boil at about 31.9°C at 760 mm Hg.

9. The azeotrope-like compositions of claim 8 wherein said compositions consist essentially of from about 60 to about 99 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 35 weight percent dichlorotrifluoroethane and from about 0.1 to about 5 weight percent 2-chloropropane.

10. The azeotrope-like compositions of claim 8 wherein said compositions consist essentially of from about 65 to about 99 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 31 weight percent dichlorotrifluoroethane and from about 0.1 to about 4 weight percent 2-chloropropane.

11. The azeotrope-like compositions of claim 8 wherein said compositions consist essentially of from about 70 to about 87 weight percent 1,1-dichloro-l- 0 fluoroethane, from about 12 to about 28 weight percent dichlorotrifluoroethane and from about 0.4 to about 2 weight percent 2-chloropropane.

12. Azeotrope-like compositions consisting , ,. essentially of from about 25 to about 99 weight percent 1,1-dichloro-l-fluoroethane, from about 1.0 to about 72 weight percent dichlorotrifluoroethane and from about 0.1 to about 3 weight percent 1,1-dichloroethane which boil at about 31.4°C at 760 mm Hg.

20

13. The azeotrope-like compositions of claim 12 wherein said compositions consist essentially of from about 63 to about 99 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 35 weight percent dichlorotrifluoroethane and from about 0.1 to about 2

25 weight percent 1,1-dichloroethane.

14. The azeotrope-like compositions of claim 12 wherein said compositions consist essentially of from about 68 to about 98 weight percent 1,1-dichloro-l-

30 fluoroethane, from about 2 to about 30 weight percent dichlorotrifluoroethane and from about 0.1 to about 2 weight percent 1,1-dichloroethane.

15. The azeotrope-like compositions of claim 12

35 wherein said compositions consist essentially of from about 69 to about 97 weight percent

1,1-dichloro-l-fluoroethane, from about 3 to about 30 weight percent dichloro¬ trifluoroethane and from about 0.1 to about 1 weight percent 1,1-dichloroethane.

16. Azeotrope-like compositions consisting essentially of from about 25 to about 98 weight percent 1,1-dichloro-l-fluoroethane, from about 1 to about 67 weight percent dichlorotrifluoroethane, from about 0.5 to about 4 weight percent 2-chloropropane and from about 1 to about 4 weight percent methanol which boil at about 30.9 C at 760 mm Hg

17. The azeotrope-like compositions of claim 16 wherein said compositions consist essentially of from about 57 to about 97 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 35 weight percent dichlorotrifluoroethane, from about 0.5 to about 4 weight percent 2-chloro.propane, and from about 1 to about 4 weight percent methanol.

18. The azeotrope-like compositions of claim 16 wherein said compositions consist essentially of from about 62 to about 95 weight percent 1,1-dichloro-l- fluoroethane, from about 2 to about 31 weight percent dichlorotrifluoroethane, from about 1 to about 3 weight percent 2-chloropropane, and from about 2 to about 4 weight percent methanol.

19. The azeotrope-like compositions of claim 16 wherein said compositions consist essentially of from about 63 to about 92 weight percent 1,1-dichloro-l- fluoroethane, from about 5 to about 30 weight percent dichlorotrifluoroethane, from about 2 to about 4 weight percent methanol and from about 1 to about 3 weight percent 2-chloropropane.

20. Azeotrope-like compositions consisting essentially of from about 25 to about 98 weight percent 1, 1-dichloro-l-fluoroethane, from about 1 to about 69 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1-chloropropane, and from about 1 to about 4 weight percent methanol which boil at about 30.9°C at 760 mm Hg.

21. The azeotrope-like compositions of claim 20 wherein said compositions consist essentially of from about 59 to about 98 weight percent 1, 1-dichloro-l- fluoroethane, from about 1 to about 35 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1-chloropropane, and from about 1 to about 4 weight percent methanol.

22. The azeotrope-like compositions of claim 20 wherein said compositions consist essentially of from about 63 to about 96 weight percent 1, 1-dichloro-l- fluoroethane, from about 2 to about 31 weight percent dichlorotrifluoroethane, from about 0.2 to about 2 weight percent 1-chloropropane, and from about 2 to about 4 weight percent methanol.

23. The azeotrope-like compositions of claim 20 wherein said compositions consist essentially of from about 65 to about 93 weight percent 1, 1-dichloro-l- fluoroethane, from about 5 to about 30 weight percent dichlorotrifluoroethane, from about 0.2 to about 1 weight percent 1-chloroρropane, and from about 2 to about 4 weight percent methanol.

24. Azeotrope-like compositions consisting essentially of from about 25 to about 98 weight percent 1,1-dichloro-l-fluoroethane, from about 1 to about 66 weight percent dichlorotrifluoroethane, from about 0.1 to about 3 weight percent 1, 1-dichloroethane, and from about 1 to about 6 weight percent methanol which boil at about 29.8°C at 760 mm Hg.

25. The azeotrope-like compositions of claim 24 wherein said compositions consist essentially of from about 55 to about 98 weight percent 1,ldichloro-1- fluoroethane, from about 1 to about 37 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1,1-dichloroethane, and from about 1 to about 6 weight percent methanol.

26. The azeotrope-like compositions of claim 24 wherein said compositions consist essentially of from about 59 to about 96 weight percent 1,1-dichloro-l- fluoroethane, from about 2 to about 33 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1,1-dichloroethane, and from about 2 to about 6 weight percent methanol.

27. The azeotrope-like compositions of claim 24 wherein said compositions consist essentially of from about 62 to about 93 weight percent 1,1-dichloro- l-fluoroethane, from about 5 to about 30 weight percent dichlorotrifluoroethane, from about 0.1 to about 2 weight percent 1,1-dichloroethane, and from about 2 to about 6 weight percent methanol.

28. Azeotrope-like compositions comprising 1,1-dichloro-l-fluoroethane, 1,l-dichloro-2,2,2- trifluoroethane and dichloromethane which boil at about 31.8°C ± about 0.4°C at 760 mm Hg.

29. Azeotrope-like compositions comprising from about 55 to about 98.5 weight percent 1, 1-dichloro- 1-fluoroethane, from about 1 to about 41 weight percent 1,l-dichloro-2,2,2-trifluoroethane, and from about 0.5 to 4.0 weight percent dichloromethane which boil at about 31.8°C at 760 mm Hg.

30. The azeotrope-like compositions of claim 29 consisting essentially of from about 55 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 41 weight percent said 1,l-dichloro- 2,2,2-trifluoroethane, and from about 0.5 to about 4.0 weight percent said dichloromethane.

31. The azeotrope-like compositions of claim 29 consisting essentially of from about 62 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 35 weight percent said 1,l-dichloro- 2,2,2-trifluoroethane, and from about 0.5 to about 3.0 weight percent said dichloromethane.

32. The azeotrope-like compositions of claim 29 consisting essentially of from about 65.5 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 32 weight percent said 1, l-dichloro- 2,2,2-trifluoroethane, and from about 0.5 to about 2.5 weight percent dichloromethane.

33. Azeotrope-like compositions comprising from about 55 to about 98.5 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 41 weight percent 1,2-dichloro-l,1,2-trifluoroethane, and from about 0.5 to 4.0 weight percent dichloromethane.

34. The azeotrope-like compositions of claim 33 consisting essentially of from about 55 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 41 weight percent said 1,2-dichloro- 1,1,2-trifluoroethane, and from about 0.5 to about 4.0 weight percent said dichloromethane.

35. The azeotrope-like compositions of claim 34 consisting essentially of from about 62 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 35 weight percent said 1,2-dichloro- 1,1,2-trifluoroethane, and from about 0.5 to about 3.0 weight percent said dichloromethane.

36. The azeotrope-like compositions of claim 34 consisting essentially of from about 65.5 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 32 weight percent said 1,2-dichloro- 1,1,2-trifluoroethane, and from about 0.5 to about 2.5 weight percent dichloromethane.

37. Azeotrope-like compositions comprising from about 55 to about 98.5 weight percent 1,1-dichloro-l- fluoroethane, from about 1 to about 21 weight percent 1,l-dichloro-2,2,2-trifluoroethane, from about 1 to about 20 weight percent 1,2-dichloro-l,1,2-trifluoro¬ ethane, and from about 0.5 to 4.0 weight percent dichloromethane.

38. The azeotrope-like compositions of claim 37 consisting essentially of from about 55 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 21 weight percent said 1,l-dichloro- 2,2,2-trifluoroethane, from about 1 to about 20 weight percent said 1,2-dichloro-l,1,2-trifluoroethane, and from about 0.5 to about 4.0 weight percent said dichloromethane.

39. The azeotrope-like compositions of claim 38 consisting essentially of from about 62 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 21 weight percent said 1,l-dichloro- 2,2,2-trifluoroethane, from about 1 to about 20 weight percent said 1,2-dichloro-l,1,2-trifluoroethane, and from about 0.5 to about 3.0 weight percent said dichloromethane.

40. The azeotrope-like compositions of claim 38 consisting essentially of from about 65.5 to about 98.5 weight percent said 1,1-dichloro-l-fluoroethane, from about 1 to about 21 weight percent said 1,l-dichloro-

10 2,2,2-trifluoroethane, from about 1 to about 20 weight percent said 1,2-dichloro-l,1,2-trifluoroethane, and from about 0.5 to about 2.5 weight percent dichloro¬ methane.

, -.

41. The azeotrope-like compositions of claim 1 wherein said dichlorotrifluoroethane is 1,l-dichloro- 2,2,2-trifluoroethane.

42. The azeotrope-like compositions of claim 1 wherein said dichlorotrifluoroethane is 1,2-dichloro-

20 1,2,2-trifluoroethane.

43. The azeotrope-like compositions of claim 1 wherein said dichlorotrifluoroethane is a mixture of 1,l-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-

25 1,2,2-trifluoroethane.

44. The azeotrope-like compositions of claim 3 wherein said dichlorotrifluoroethane is 1,l-dichloro- 2,2,2-trifluoroethane.

30

45. The azeotrope-like compositions of claim 3 wherein said dichlorotrifluoroethane is 1,2-dichloro- 1,2,2-trifluoroethane.

35

46. The azeotrope-like compositions of claim 3 wherein said dichlorotrifluoroethane is a mixture of 1, 1-dichloro-l,2,2-trifluoroethane and 1,2-dichloro- _c 1,2,2-trifluoroethane.

47. The azeotrope-like compositions of claim 1 wherein said composition contains a stabilizer.

0 48. A method of cleaning a solid surface comprising treating said surface with an azeotrope-like composition of claim 1.

5

0

5

0

5