WO1992010453A1

WO1992010453A1 - Stabilized 1,1-dichloro-1-fluoroethane

Info

Publication number: WO1992010453A1
Application number: PCT/US1991/008997
Authority: WO
Inventors: Kane David Cook; Chien Chi Li; Rajat Subhra Basu
Original assignee: Allied-Signal Inc.
Priority date: 1990-12-14
Filing date: 1991-11-27
Publication date: 1992-06-25
Also published as: TW217423B

Abstract

The present invention provides stabilized compositions comprising 1,1-dichloro-1-fluoroethane and effective stabilizing amounts of stabilizer selected from the group consisting of alkanol having 4 to 7 carbon atoms, nitroalkane having 1 to 3 carbon atoms, 1,2-epoxyalkane having 2 to 7 carbon atoms, phosphite ester having 12 to 30 carbon atoms, ether having 3 or 4 carbon atoms, unsaturated compound having 4 to 6 carbon atoms, acetal having 4 to 7 carbon atoms, ketone having 3 to 5 carbon atoms, or amine having 6 to 8 carbon atoms alone or in mixtures thereof in any proportions. Stabilized 1,1-dichloro-1-fluoroethane is useful in a variety of vapor degreasing, cold cleaning, and solvent cleaning applications including defluxing.

Description

STABILIZED 1.1-DICHLORO-l-FLUOROETHANE

FIELD OF THE INVENTION

The present invention relates to stabilized 1,1-dichloro-l-fluoroethane. Stabilized 1,1-dichloro-l-fluoroethane is useful in a variety of vapor degreasing, cold cleaning, and solvent cleaning applications including defluxing.

BACKGROUND OF THE INVENTION

Vapor degreasing and solvent cleaning with fluorocarbon based solvents have found widespread use in industry 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 contamination. Final evaporation of solvent from the object leaves behind no residue as would be the case where the object is simply washed in liquid solvent.

For difficult to remove soils where elevated temperature is necessary to improve the cleaning action of the solvent, or for large volume assembly line operations where the cleaning of metal parts and assemblies must be done efficiently and quickly, 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 number of solvents are used. In most cold cleaning applications, the soiled part is either immersed in the fluid or wiped with rags or similar objects soaked in solvents and allowed to air dry.

Fluorocarbon solvents, such as 1,1-dichloro-l-fluoroethane, have attained widespread use in recent years as effective, nontoxic, and nonflammable agents useful in degreasing applications and other solvent cleaning applications. 1,1-Dichloro-l-fluoroethane 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 and the like. The art is continually seeking new hydrochlorofluorocarbon solvents which offer alternatives for new and special applications for vapor degreasing and other cleaning applications. Solvents which are based on hydrochlorofluorocarbons are considered to be stratospherically safe substitutes for presently used fully halogenated chlorofluorocarbons. The latter are suspected of causing environmental problems in connection with the earth's protective ozone layer. Mathematical models have substantiated that hydrochlorofluorocarbons, such as 1,1-dichloro-l-fluoroethane (known in the art as HCFC-141b), will not adversely affect atmospheric chemistry, being negligible contributors to ozone depletion and to green-house global warming in comparison to the fully halogenated species.

Hydrochlorofluorocarbons such as 1,1-dichloro-l-fluoroethane hydrolyze to form hydrogen chloride. While 1,1-dichloro-l-fluoroethane is useful as a cleaning solvent, the 1,1-dichloro-l-fluoroethane should be stabilized against possible changes during storage and use. When metallic materials are present such as occurs in many cleaning applications, the problem is worsened because the metal acts as a catalyst and causes the hydrolysis of 1,1-dichloro-l-fluoroethane to increase exponentially. Because metallic materials such as Al-2024 which is an aluminum based alloy having about 4.5% copper, copper, cold rolled steel, galvanized steel, stainless steel, and zinc are commonly used in cleaning apparatus, the hydrolysis problem is common. Also, ultraviolet light decomposes hydrochlorofluorocarbons such as 1,1-dichloro-l-fluoroethane. Hydrochlorofluorocarbons such as dichlorotrifluoroethane are known to react with water to form acids such as hydrogen chloride and hydrogen fluoride or to react with alcoholic hydroxyl groups to form aldehydes and ketones. Known stabilizers for compositions of l,l-dichloro-2,2,2-trifluoroethane and alcohol include: epoxy compounds as taught by Kokai Patent Publication 56,630 published March 3, 1989; combinations of styrene and epoxy compounds as taught by Kokai Patent Publication 56,631 published March 3, 1989; combinations of styrene compounds and phenols as taught by Kokai Patent Publication 56,632 published March 3, 1989; combinations of epoxy and styrene compounds and phenols as taught by Kokai Patent Publication 128,943 published May 22, 1989; hydrocarbons containing nitro groups as taught by Kokai

Patent Publication 128,944 published May 22, 1989; combinations of hydrocarbons containing nitro groups and epoxy compounds as taught by Kokai Patent Publication

128,945 published May 22, 1989; and phenols as taught by Kokai Patent Publication 265,042 published October 23,

1989. Kokai Patent Publication 139,539 teaches l,2-dichloro-l,l,2-trifluoroethane based azeotropic compositions which are stabilized with at least one of nitro compounds, phenols, amines, ethers, amylenes, esters, organic phosphites, epoxides, furans, alcohols, ketones, and triazoles.

Because 1,1-dichloro-l-fluoroethane is considered one of the leading substitutes for chlorofluorocarbons and thus, will be used in many applications in large quantities, it would be useful to have a stabilized 1,1-dichloro-l-fluoroethane which can be used and stored without loss of acceptable properties. SUMMARY OF THE INVENTION

The present invention provides a composition comprising 1,1-dichloro-l-fluoroethane and an effective stabilizing amount of stabilizer selected from the group consisting of alkanol having 4 to 7 carbon atoms, nitroalkane having 1 to 3 carbon atoms, 1,2-epoxyalkane having 2 to 7 carbon atoms, phosphite ester having 12 to 30 carbon atoms, ether having 3 or 4 carbon atoms, unsaturated compound having 4 to 6 carbon atoms, acetal having 4 to 7 carbon atoms, ketone having 3 to 5 carbon atoms, or amine having 6 to 8 carbon atoms alone or in mixtures thereof in any proportions.

The stabilized 1,1-dichloro-l-fluoroethane undergoes minimal hydrolysis. Thus, the stabilized 1,1-dichloro-l-fluoroethane is especially useful in cleaning applications wherein a solvent is typically exposed to water and metallic materials.

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

DESCRIPTION OF THE INVENTION

The 1,1-dichloro-l-fluoroethane used in the present invention can be prepared by any known method including the reaction of commercially available vinylidene chloride with anhydrous hydrogen fluoride or the reaction of commercially available 1,1,1-trichloroethane with anhydrous hydrogen fluoride. Examples of useful alkanols having 4 to 7 carbon atoms are 2-methyl-2-proρanol; 2-methyl-2-butanol; 1-pentanol; 2-pentanol; 3-pentanol; and 3-ethyl-3-ρentanol. The preferred alkanols are 2-methyl-2-ρropanol and 3-pentanol. If an alkanol is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and alkanol is alkanol. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and alkanol is alkanol.

Examples of useful nitroalkanes having 1 to 3 carbon atoms include nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane. The preferred nitroalkanes are nitromethane and nitroethane. If a nitroalkane is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and nitroalkane is nitroalkane. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and nitroalkane is nitroalkane.

Examples of useful 1,2-eρoxyalkanes having 2 to 7 carbon atoms include epoxyethane; 1,2-epoxypropane; 1,2-epoxybutane; 2,3-epoxybutane; 1,2-epoxyρentane; 2,3-epoxypentane; 1,2-epoxyhexane; and 1,2-epoxyheptane. The preferred 1,2-epoxyalkanes are 1,2-epoxybutane and 1,2-epoxyproρane. If a 1,2-epoxyalkane is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and 1,2-epoxyalkane is 1,2-epoxyalkane. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and 1,2-epoxyalkane is 1,2-epoxyalkane. Examples of useful phosphite esters having 12 to 30 carbon atoms include diphenyl phosphite; triphenyl phosphite; triisodecyl phosphite; triisooctyl phosphite; and diisooctyl phosphite. The preferred phosphite esters 5 are triisodecyl phosphite (hereinafter TDP) and triisooctyl phosphite (hereinafter TOP) . If a phosphite ester is used, preferably, about 0.01 to about 2 percent based on the total weight of the

1,1-dichloro-l-fluoroethane and phosphite ester is _Q phosphite ester. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and phosphite ester is phosphite ester.

₅ Examples of useful ethers having 3 or 4 carbon atoms include diethylene oxide; 1,2-butylene oxide; 2,3-butylene oxide; and dimethoxymethane. The preferred ethers are diethylene oxide and dimethoxymethane. If an ether is used, preferably, about 0.01 to about 2 percent based on the total weight of the 0

1,1-dichloro-l-fluoroethane and ether is ether. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and ether is ether. 5

Examples of useful unsaturated compounds having 4 to 6 carbon atoms include 1,4-butyne diol; 1,5-ρentyne diol; and 1,6-hexyne diol. The preferred unsaturated compounds are 1,4-butyne diol and 1,5-pentyne diol. If an unsaturated compound is used, preferably, about 0.01 to 0 about 2 percent based on the total weight of the

1,1-dichloro-l-fluoroethane and unsaturated compound is unsaturated compound. More preferably, about 0.02 to about 1 percent based on the total weight of the

1,1-dichloro-l-fluoroethane and unsaturated compound is unsaturated compound. Examples of useful acetals having 4 to 7 carbon atoms include dimethoxyethane; 1,1-diethyoxyethane; and dipropoxymethane. The preferred acetals are dimethoxyethane and dipropoxymethane. If an acetal is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and acetal is acetal. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and acetal is acetal.

Examples of useful ketones having 3 to 5 carbon atoms include 2-propanone; 2-butanone; and 3-pentanone. The preferred ketones are 2-ρropanone and 2-butanone. If a ketone is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and ketone is ketone. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and ketone is ketone.

Examples of useful amines having 6 to 8 carbon atoms include triethyl amine, dipropyl amine, and diisobutyl amine. The preferred amines are triethyl amine and dipropyl amine. If an amine is used, preferably, about 0.01 to about 2 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and amine is amine. More preferably, about 0.02 to about 1 percent based on the total weight of the 1,1-dichloro-l-fluoroethane and amine is amine.

These materials are all known materials and most are commercially available. The term "effective stabilizing amounts" as used herein means that amount of each of the alkanols, nitroalkanes, 1,2-epoxyalkanes, phosphite esters, ethers, unsaturated compounds, acetals, ketones, and amines which in combination with the 1,1-dichloro-l-fluoroethane component allows the composition to be used and stored without loss of acceptable properties.

The stabilizers are effective in preventing the hydrolysis of the 1,1-dichloro-l-fluoroethane component in the presence of Aluminum-2024, copper, cold rolled steel, galvanized steel, and various grades of stainless steel. Typically, as will be explained below, when the stabilized 1,1-dichloro-l-fluoroethane is in contact with metallic materials, the Cl^" concentration is less than about 50 parts per million. Also, the metallic surface remains shiny.

The stabilized 1,1-dichloro-l-fluoroethane of the present invention may be prepared in any known manner including weighing each component and then mixing the components together.

Stabilized 1,1-dichloro-l-fluoroethane is useful in a variety of vapor degreasing, cold cleaning, and solvent cleaning applications including defluxing.

The present stabilized 1,1-dichloro-l-fluoroethane may also be blended with at least one common solvent component such as other hydrochlorofluorocarbons, hydrofluorocarbons, alkanols having 1 or 2 carbon atoms, alkanes, and dichloroethylene. These other components may be used in amounts of up to about 50 weight percent based on the total weight of the stabilized 1,1-dichloro-l-fluoroethane and the at least one other component. Examples of useful hydrochlorofluorocarbons include chlorodifluoromethane (known in the art as HCFC-22); dichlorotrifluoroethane (known in the art as HCFC-123 or

HCFC-123a); l-chloro-l,l-difluoroethane (known in the art as HCFC-142b); 2,2-dichloro-l,l,1,3,3-pentafluoropropane

(known in the art as HCFC-225a);

1,2-dichloro-l,2,3,3,3-pentafluoropropane (known in the art as HCFC-225ba);

1,2-dichloro-l,1,2,3,3-pentafluoropropane (known in the art as HCFC-225bb); l,l-dichloro-2,2,3,3,3-pentafluoropropane (known in the art as HCFC-225ca);

1,3-dichloro-l,1,2,2,3-pentafluoropropane (known in the art as HCFC-225cb); 1,1-dichloro-l,2,2,3,3-pentafluoropropane (known in the art as HCFC-225cc);

1,2-dichloro-l,1,3,3,3-pentafluoropropane (known in the art as HCFC-225d);

1,3-dichloro-l,1,2,3,3-pentafluoropropane (known in the art as HCFC-225ea); and

1,1-dichloro-l,2,3,3,3-pentafluoropropane (known in the art as HCFC-225eb).

Examples of useful hydrofluorocarbons include pentafluoroethane (known in the art as HFC-125); 1,1,1-trifluoroethane (known in the art as HFC-143a); and 1,1-difluoroethane (known in the art as HFC-152a) .

Examples of useful alkanols having 1 or 2 carbon atoms are methanol and ethanol. Examples of useful alkanes include propane; butane; 2-methylpropane; pentane; 2-methylbutane; and 2,2--dimethylproρane. Examples of dichloroethylene are trans-l,2-dichloroethylene and cis-1,2-dichloroethylene. In the process embodiment of the invention, the stabilized 1,1-dichloro-l-fluoroethane of the invention may be used to clean solid surfaces by treating the surfaces with the compositions in any manner well known in the art such as by dipping or spraying or use of conventional degreasing apparatus.

The 1,1-dichloro-l-fluoroethane and stabilizers should be used in sufficiently high purity so as to avoid the introduction of adverse influences upon the solvency properties of the system.

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

EXAMPLES 1-39

Two week stability tests are done as follows:

HCFC-141b is saturated with water at room temperature. Each of the stabilizers listed below is combined in an effective amount with the HCFC-141b. 125 ml of HCFC-141b is transferred into a 250 ml Pyrex flask which is connected to a water/glycol cooled condenser.

On top of the condenser, a "Drierite" desiccant is provided to prevent ambient moisture leaking into the solvent. A metal coupon is situated in the middle of the liquid-vapor phase. Five common metallic alloys are investigated. They are: Aluminum-2024(hereinafter

Al-2024), Copper(hereinafter Cu), Cold Rolled steel(hereinafter CRS), Galvanized Steel(hereinafter GS), and stainless steel (316 grade). Each stabilized HCFC-141b solvent system is under total reflux at its boiling temperature for a two week period. Observation is made daily on the change of the metal surface including the loss of luster of the metal surface and stain or corrosion on the metal surface, if any and the solvent including coloration of the solvent, increased viscosity of the solvent and most importantly, the rate of change of the viscosity.

The pH values are determined for each stabilized HCFC-141b solvent system before and after the test. The Cl ion concentration in each stabilized HCFC-141b solvent system is determined by ion chromatography. The chloride level is below 50 ppm in each stabilized HCFC-141b solvent system.

EXAMPLE STABILIZER

1 2-methy1-2-propano1

2 2-methyl-2-butanol

3 1-ρentanol

4 2-pentanol

5 3-pentanol

6 3-ethyl-3-pentanol

7 nitromethane

8 nitroethane

9 1-nitropropane

10 l-nitropropane

11 epoxyethane

12 1,2-epoxypropane

13 1,2-epoxybutane

14 2,3-eρoxybutane 5 1,2-epoxypentane 6 2,3-epoxypentane 7 1,2-eρoxyhexane 8 1,2-eρoxyheptane XA P E STABILIZER

19 diphenyl phosphite 20 triphenyl phosphite 5 21 triisodecyl phosphite 22 triisooctyl phosphite 23 diisooctyl phosphite 24 diethylene oxide 25 1,2-butylene oxide

10 26 2,3-butylene oxide 27 dimethoxymethane

28 1,4-butyne diol

29 1,5-pentyne diol

30 1,6-hexyne diol

15 31 dimethoxyethane

32 1,1-diethyoxyethane

33 dipropoxymethane

34 2-propanone

35 2-butanone

36 3-pentanone

20

37 triethyl amine

38 dipropyl amine

39 diisobutyl amine

EXAMPLES 40-78

25

Each of the stabilized 1,1-dichloro-l-fluoroethane compositions of Examples 1 through 39 is combined with up to 50 weight percent of 1,l-dichloro-2,2,2-trifluoroethane to form a solvent blend.

30

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. Stabilized compositions comprising 1,1-dichloro-l-fluoroethane and an effective stabilizing amount of stabilizer selected from the group consisting of alkanol having 4 to 7 carbon atoms, nitroalkane having 1 to 3 carbon atoms, 1,2-epoxyalkane having 2 to 7 carbon atoms, phosphite ester having 12 to 30 carbon atoms, ether having 3 or 4 carbon atoms, unsaturated compound having 4 to 6 carbon atoms, acetal having 4 to 7 carbon atoms, ketone having 3 to 5 carbon atoms and amine having 6 to 8 carbon atoms.

2. The stabilized compositions of claim 1 wherein said alkanol is an alkanol selected from the group consisting of 2-methyl-2-propanol, 2-methyl-2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, and 3-ethyl-3-pentanol.

3. The stabilized compositions of claim 1 wherein said nitroalkane is a nitroalkane selected from the group consisting of nitromethane- nitroethane, 1-nitropropane, and 2-nitropropane.

4. The stabilized compositions of claim 1 wherein said 1,2-epoxyalkane is a 1,2-epoxyalkane selected from the group consisting of epoxyethane; 1,2-epoxypropane; 1,2-epoxybutane; 2,3-epoxybutane; 1,2-epoxypentane; 2,3-epoxypentane; 1,2-epoxyhexane; and 1,2-epoxyheptane.

5. The stabilized compositions of claim 1 wherein said phosphite ester is a phosphite ester selected from the group consisting of diphenyl phosphite; triphenyl phosphite; triisodecyl phosphite; triisooctyl phosphite; and diisooctyl phosphite.

6. The stabilized compositions of claim 1 wherein said ether is an ether selected from the group consisting of diethylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and dimethoxymethane.

7. The stabilized compositions of claim 1 wherein said unsaturated compound is an unsaturated compound selected from the group consisting of 1,4-butyne diol, 1,5-pentyne diol, and 1,6-hexyne diol.

8. The stabilized compositions of claim 1 wherein said acetal is an acetal selected from the group consisting of dimethoxyethane, 1,1-diethyoxyethane, and dipropoxymethane.

9. The stabilized compositions of claim 1 wherein said ketone is a ketone selected from the group consisting of 2-propanone, 2-butanone, and 3-pentanone.

10. The stabilized compositions of claim 1 wherein said amine is an amine selected from the group consisting of triethyl amine, dipropyl amine, and diisobutyl amine.