WO1990015169A1

WO1990015169A1 - Azeotrope-like compositions of 1,1-dichloro-1-fluoroethane and dichlorotrifluoroethane

Info

Publication number: WO1990015169A1
Application number: PCT/US1990/003185
Authority: WO
Inventors: Ellen Louise Swan; Rajat Subhra Basu; Ian R. Shankland
Original assignee: Allied-Signal Inc.
Priority date: 1989-06-06
Filing date: 1990-06-05
Publication date: 1990-12-13
Also published as: AU5813590A

Abstract

Azeotrope-like compositions comprising 1,1-dichloro-1-fluoroethane and dichlorotrifluoroethane are stable and have utility as blowing agents, degreasing agents and as solvents in a variety of industrial cleaning applications including cold cleaning and defluxing of printed circuit boards.

Description

DESCRIPTION

AZEOTROPE-LIKE COMPOSITIONS OF 1.1-DICHLORO-l-FLUOROETHANE AND DICHLOROTRIFLUOROETHANE

This application is a continuation-in-part of patent application Serial No. 362,294 filed June 6. 1989.

Field of the Invention

This invention relates to azeotrope-like or essentially constant-boiling mixtures of 1,1-dichloro-l- fluoroet ane and dichlorotrifluoroethane. These mixtures are useful as blowing agents and in a variety of vapor degreasing, cold cleaning and solvent cleaning applications including defluxing.

CROSS-REFERENCE TO RELATED APPLICATIONS

Co-pending, commonly assigned patent application Serial No. 297.467, filed 01/17/89, which is a continuation-in-part application of Serial No. 290.124, filed 12/27/88, discloses azeotrope-like mixtures of 1,1-dichloro-l-fluoroethane; dichlorotrifluoroethane; and methanol.

Co-pending, commonly assigned patent application Serial No. 345,732. filed 05/01/89. discloses azeotrope- like mixtures of 1.1-dichloro-l-fluoroethane; dichloro¬ trifluoroethane; nitromethane; and methanol or ethanol.

Co-pending, commonly assigned patent application Serial No. 412.080. filed 09/25/89, discloses azeotrope- like compositions of 1.1-dichloro-l-fluoroethane; dichlorotrifluoroethane; methanol; and cyclopentane. Co-pending, commonly assigned patent application Serial No. 417,134, filed 10/04/89. discloses azeotrope- like mixtures of 1.1-dichloro-l-fluoroethane; dichloro¬ trifluoroethane; and nitromethane.

Co-pending, commonly assigned patent application Serial No. 423.993, filed 10/19/89, discloses azeotrope- like compositions of dichlorotrifluoroethane and methanol.

Co-pending, commonly assigned patent application

Serial No. (Attorney Docket 30-2822(4520)), filed 11/10/89, discloses azeotrope-like compositions of 1,1-dichloro-l-fluoroethane; dichlorotrifluoroethane; and a mono- or di-chlorinated C_ or C_ alkane.

Co-pending, commonly assigned patent application

Serial No. (Attorney Docket 30-2823(4520)), filed 11/10/89, discloses azeotrope-like compositions of 1,1-dichloro-l-fluoroethane; dichlorotrifluoroethane; methanol; and a mono- or di-chlorinated C or C alkane.

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 trichlorotrifluoro¬ ethane, have attained widespread use in recent years as effective, nontoxic, and nonflammable agents useful in degreasing applications and other solvent cleaning applications. Trichlorotrifluoroethane has been found to have satisfactory solvent power for greases, oils, 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 has looked towards azeotrope or azeotrope- like compositions including the desired fluorocarbon components such as trichlorotrifluoroethane which include components which contribute additionally desired characteristics, such as polar functionality, increased solvency power, and stabilizers. Azeotropic or azeotrope- like compositions are desired because they do not fractionate upon boiling. This behavior is desirable because in the previously described vapor degreasing equipment with which these solvents are employed, redistilled material is generated for final rinse- cleaning. Thus, the vapor degreasing system acts as a still. Unless the solvent composition exhibits a constant boiling point, i.e., is azeotrope-like, fractionation will occur and undesirable solvent distribution may act to upset the cleaning and safety of processing. Preferential evaporation of the more volatile components of the solvent mixtures, which would be the case if they were not azeotrope-like, 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 azeotrope-like mixtures which offer alternatives for new and special applications for vapor degreasing and other cleaning applications. Currently, of particular interest, are fluorocarbon based azeotrope-like mixtures which are considered to be stratospherically safe substitutes for presently used fully halogenated chloro- fluorocarbonε. The latter are suspected of causing environmental problems in connection with the earth's protective ozone layer. Mathematical models have substantiated that hydrochlorofluorocarbons, r.uch as

1,1-dichloro-l-fluoroethane (HCFC-141b) and dichloro¬ trifluoroethane (HCFC-123 or HCFC-123a). 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. Both HCFC-141b and dichlorot ifluoroethane are known to be useful as solvents.

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-1-fluoroethane; dichlorotrifluoroethane; and ethanol.

The art is also seeking new fluorocarbon azeotrope-like mixtures which are useful as blowing agents. Fluorocarbons such as trichlorofluoromethane have been used commercially as auxiliary blowing agents for flexible foams and as primary blowing agents for rigid foams. Polyurethane foams are manufactured by reacting and foaming a mixture of ingredients comprising in general an organic isocyanate, such as pure or crude toluene diisocyanate or a polymeric diisocyanate, with an appropriate amount of polyol or mixture of polyols. in the presence of a volatile liquid blowing agent, which vaporizes during the reaction, causing the polymerizing mixture to foam. The reactivity of these ingredients is enhanced through the use of various additives such as amine and/or tin catalysts and surfactant materials which serve to control and adjust cell size as well as to stabilize the foam structure during its formation.

Flexible polyurethane foams are generally manufactured using an excess of diisocyanate which reacts with the water also included as a raw material, producing gaseous carbon dioxide, causing foam expansion. Flexible foams are widely used as cushioning materials in items such as furniture, bedding and automobiles. Auxiliary physical blowing agents such as methylene chloride and/or trichlorofluoromethane(CFC-ll) are required in addition to the water/diisocyanate blowing mechanism in order to produce low density, soft grades of flexible polyurethane foam.

Rigid polyurethane foams are almost exclusively expanded using CFC-11 as the blowing agent. Some rigid foam formulations do incorporate small amounts of water in addition to the CFC-11. but the CFC-11 is the major blowing agent component. Other formulations sometimes use small amounts of the more volatile dichlorodifluoromethane (CFC-12) in addition to CFC-11 for producing so-called froth-type foams. Rigid foams are closed-cell foams in ' which the CFC-11 vapor is trapped in the matrix of cells. These foams offer excellent thermal insulation characteristics, due in part to the low vapor thermal conductivity of CFC-11. and are used widely in thermal insulation applications such as roofing systems, building panels, refrigerators and freezers and the like.

Because HCFC-141b has a low molecular weight. HCFC-141b might be considered a good blowing agent candidate as disclosed by U.S. Patent 4.271.273. However, a disadvantage of HCFC-141b as a blowing agent is that the vapor of HCFC-141b is flammable. As a result, the shipping, handling and use of HCFC-141b have to be carefully controlled due to the potential flammability.

Because HCFC-123 is nonflammable, HCFC-123 might be considered a good blowing agent candidate as taught by U.S. Patent 4,076,644. However, a disadvantage of HCFC-123 as a blowing agent is that HCFC-123 has a high molecular weight and as a result, HCFC-123 is not an efficient blowing agent. U.S. Patent 4,624,970 discloses the use of mixtures of CFC-11 and HCFC-123 or HCFC-123a to blow urethane type foams. Such blowing agent mixtures were found to permit greater amounts of low cost aromatic polyester polyols to be used in rigid foam formulations without serious degradation in foam properties.

It is an object of this invention to provide novel azeotrope-like compositions based on HCFC-141b and dichlorotrifluoroethane which are liquid at room temperature, which will not fractionate substantially under the process of distillation or evaporation, and which are useful as blowing agents for the preparation of polyurethane and polyisocyanurate foams and as solvents for use in vapor degreasing and other solvent cleaning applications including defluxing applications.

A further object of the invention is to provide novel environmentally acceptable blowing agents for the production of rigid and flexible polyurethane and polyisocyanurate foams.

Another object of the invention is to provide novel environmentally acceptable solvents for use in the aforementioned applications.

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

DESCRIPTION OF THE INVENTION

In accordance with the invention, novel mixtures have been discovered comprising 1,1-dichloro-l-fluoro¬ ethane and dichlorotrifluoroethane. Also, novel azeotrope- like or constant-boiling compositions have been discovered comprising HCFC-141b and dichlorotrifluoroethane. The dichlorotrifluoroethane component can be one of its isomerε: 1,l-dichloro-2.2,2-trifluoroethane (HCFC-123); 1.2-dichloro-1.1.2-trifluoroethane (HCFC-123a); or mixtures thereof in any proportions.

5 The preferred isomer of dichlorotrifluoroethane is HCFC-123. Preferably, "commercial HCFC-123" which 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 trichloromono- 0 fluoromethane, trichlorotrifluoroethane, and methylene chloride which due to their presence in insignificant amounts, have no deleterious effects on the properties of the azeotrope-like compositions, is used. "Commercial HCFC-123" is also available as "ultra-pure" HCFC-123 which 5 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.

Preferably, the novel azeotrope-like compositions 0 comprise effective amounts of 1.1-dichloro-l-fluoroethane and dichlorotrifluoroethane. The term "effective amounts" as used herein means the amount of each component which upon combination with the other component, results in the formation of the present azeotrope-like composition. 5

Novel azeotrope-like compositions also preferably comprise from about 0.5 to about 99.5 weight percent of 1.1-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent of l.l-dichloro-2,2.2-trifluoroethane. 30

Novel azeotrope-like compositions also preferably comprise 1,1-dichloro-l-fluoroethane and 1,1-dichloro- 2,2,2-trifluoroethane which boil at about 29.9°C +. about 2.1°C at 760 mm Hg (101 kPa), and more preferably, about 3531.2°C ± about 0.8°C at 760 mm Hg (101 kPa). Preferably, novel azeotrope-like compositions comprise from about 0.5 to about 99.5 weight percent of 1,1-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent of 1,l-dichloro-2,2,2-trifluoroethane which boil at about 29.9°C ± about 2.1°C at 760 mm Hg (101 kPa) .

More preferably, novel azeotrope-like compositions have been discovered comprising from about 50 to about 99.5 weight percent of 1.1-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent of 1.1-dichloro- 2,2.2-trifluoroethane which boil at about 31.2°C ± about 0.8°C at 760 mm Hg (101 kPa).

For solvent applications, preferably the azeotrope- like compositions of the invention comprise from about 60 to about 99.5 weight percent of 1.1-dichloro-l-fluoro¬ ethane and from about 0.5 to about 40 weight percent of 1.1-dichloro-2,2,2-trifluoroethane.

More preferably for solvent applications, the azeotrope-like compositions of the invention comprise from about 67 to about 99.5 weight percent of 1,1-dichloro-l- fluoroethane and from about 0.5 to about 33 weight percent of l.l-dichloro-2.2,2-trifluoroethane.

Even more preferably for solvent applications, the azeotrope-like compositions of the invention comprise from about 70 to about 99.5 weight percent of 1,1-dichloro-l- fluoroethane and from about 0.5 to about 30 weight percent of 1.l-dichloro-2.2.2-trifluoroethane.

Even more preferably for solvent applications, the azeotrope-like compositions of the invention comprise from about 78 to about 99.5 weight percent of 1,1-dιchloro-l- fluoroethane and from about 0.5 to about 22 weight percent of 1,l-dichloro-2,2.2-trifluoroethane. Most preferably for solvent applications, the azeotrope-like compositions of the invention comprise from about 85 to about 99.5 weight percent of 1.1-dichloro-l- fluoroethane and from about 0.5 to about 15 weight percent of 1,l-dichloro-2,2.2-trifluoroethane.

For blowing agent applications, preferably the azeotrope-like compositions of the invention comprise from about 50 to about 69.6 weight percent of 1.1-dichloro-l- fluoroethane and from about 30.4 to about 50 weight percent of 1,l-dichloro-2.2,2-trifluoroethane. It has been found that the use of at least 30.4 weight percent HCFC-123 in the vapor composition inhibits the flammability of HCFC-141b. As such, the present azeotrope-like compositions of HCFC-141b and HCFC-123 are superior as blowing agents when compared with HCFC-141b used alone. The present azeotrope-like compositions of HCFC-141b and HCFC-123 are also more efficient as blowing agents when compared with HCFC-123 used alone.

Most preferably for blowing agent applications, the azeotrope-like compositions of the invention comprise from about 50 to about 67 weight percent of 1.1-dichloro-l- fluoroethane and from about 33 to about 50 weight percent of l,l-dichloro-2,2,2-trifluoroethane.

Novel azeotrope-like compositions also preferably comprise from about 0.5 to about 99.5 weight percent of 1,1-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent of 1,2-dichloro-l.l.2-trifluoroethane.

Novel azeotrope-like compositions also preferably comprise 1.1-dichloro-l-fluoroethane and 1,2-dichloro- 1,1.2-trifluoroethane which boil at about 31.1°C +. about 1.0°C at 760 mm Hg (101 kPa). and more preferably, about 31.5°C + about 0.5°C at 760 mm Hg (101 kPa). Preferably, novel azeotrope-like compositions comprise from about 0.5 to about 99.5 weight percent of 1,l-dichloro-1-fluoroethane and from about 0.5 to about 99.5 weight percent of 1,2-dichloro-l.1,2-trifluoroethane which boil at about 31.1°C ± about 1.0°C at 760 mm Hg (101 kPa).

More preferably, novel azeotrope-like compositions have been discovered comprising from about 50 to about 99.5 weight percent of 1,1-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent of 1,2-dichloro-l,1,2-trifluoroethane which boil at about 31.5°C + about 0.5°C at 760 mm Hg (101 kPa).

it should be understood that the compositional ranges set forth above for the azeotrope-like compositions of 1,1-dichloro-l-fluoroethane and 1,l-dichloro-2,2,2- trifluoroethane for solvent and blowing agent applications respectively also apply to the azeotrope-like compositions of 1.1-dichloro-l-fluoroethane and 1,2-dichloro-l,1,2- trifluoroethane.

Novel azeotrope-like compositions also preferably comprise from about 0.5 to about 99.5 weight percent of l,ι-dichloro-1-fluoroethane and from about 0.5 to about

99.5 weight percent of a mixture of l.l-dichloro-2.2,2- trifluoroethane and 1,2-dichloro-l,1,2-trifluoroethane.

Novel azeotrope-like compositions also preferably comprise 1.1-dichloro-l-fluoroethane and a mixture of

1.l-dichloro-2,2,2-trifluoroethane and 1.2-dichloro-l,1,2- trifluoroethane which boil at about 30.0°C +. about 2.0°C at 760 mm Hg (101 kPa), and more preferably, about 31.3°C ± about 0.7°C at 760 mm Hg (101 kPa).

Preferably, novel azeotrope-like compositions comprise from about 0.5 to about 99.5 weight percent of 1,1-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent of a mixture of 1.l-dichloro-2,2,2- trifluoroethane and 1,2-dichloro-l,1.2-trifluoroethane which boil at about 30.0°C ± about 2.0°C at 760 mm Hg (101 kPa) .

Preferably, novel azeotrope-like compositions have been discovered comprising from about 50 to about 99.5 weight percent of 1,1-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent of a mixture of 1.l-diςhloro-2,2,2-trifluoroethane and l,2-dichloro-l,2.2- trifluoroethane which boil at about 31.3°C + about 0.7°C at 760 mm Hg.

It should be understood that the aforementioned compositional ranges for azeotrope-like compositions of 1,l-dichloro-l-fluoroethane and 1.l-dichloro-2,2,2- trifluoroethane for solvent and blowing agent applications respectively also apply to azeotrope-like compositions of 1,l-dichloro-l-fluoroethane and a mixture of 1,1-dichloro- 2,2,2-trifluoroethane and 1,2-dichloro-l,1,2-trifluoro¬ ethane.

Although it is not believed that a true azeotropic system is formed with 1.l-dichloro-l-fluoroethane and dichlorotrifluoroethane. the term "azeotrope-like" is used herein for the mixtures of the present invention because in the claimed proportions, the compositions of 1,1- dichloro-1-fluoroethane and dichlorotri luoroethane components are constant-boiling or essentially constant- boiling and for some reason, which is not fully understood, remain or hang together in a vapor degreaser.

As previously noted, the preferred dichlorotri- fluoroethane component is "commercial HCFC-123".

The azeotrope-like compositions of the invention containing a mixture of HCFC-123 and HCFC-123a are azeotrope-like in that they are constant-boiling or essentially constant-boiling. It is not known whether this is the case because the separate binary azeotrope- like compositions with HCFC-123 and HCFC-123a have boiling points so close to one another as to be indistinguishable for practical purposes or whether HCFC-123 and HCFC-123a form a ternary azeotrope with 1,l-dichloro-l-fluoroethane.

All compositions within the indicated ranges, as well as certain compositions outside the indicated ranges, are azeotrope-like. as defined more particularly below.

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

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 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.

For the purpose of this discussion, azeotrope-like composition is intended to mean that the composition behaves like an azeotrope, i.e. has constant-boiling characteristics or a tendency not to fractionate upon boiling or evaporation. Thus, in such compositions, the composition of the vapor formed during boiling or evaporation is identical or substantially identical to the original liquid composition. Hence, during boiling or evaporation, the liquid composition, if it changes at all, changes only to a minimal or negligible extent. This is to be contrasted with non-azeotrope-like compositions in which during boiling or evaporation, the liquid composition changes to a substantial degree. 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 separate components. If the mixture is non-azeotrope-like, the mixture will fractionate, i.e. separate into its various components with the lowest boiling component distilling off first, and so on. 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 does not behave like an azeotrope. Of course, upon distillation of an azeotrope- like composition such as in a vapor degreaser, the true azeotrope will form and tend to concentrate.

It follows from the above that another characteristic of azeotrope-like compositions is that there is a range of compositions containing the same components in varying proportions which are azeotrope-like or constant-boiling. All such compositions are intended to be covered by the term azeotrope-like or constant- boiling as used herein. As an example, it is well known that at differing pressures, the composition of a given azeotrope-like composition will vary at least slightly as does the boiling point of the composition. Thus, an azeotrope-like composition of A and B represents a unique type of relationship but with a variable composition depending on temperature and/or pressure. As is readily understood by persons skilled in the art, the boiling point of the azeotrope-like composition will vary with the pressure.

The azeotrope-like compositions of the invention are useful as blowing agents and solvents in a variety of vapor degreasing, cold cleaning and solvent cleaning applications including defluxing. We have found that when an azeotrope-like composition of 50 weight percent HCFC-141b and 50 weight percent HCFC-123 is totally evaporated, the HCFC-123 still masks the flammability of 5 the HCFC-141b.

In one process embodiment of the invention, the azeotrope-like compositions of the invention may be used to clean solid surfaces by treating said surfaces with 10. said compositions in any manner well known to the art such as by dipping or spraying or use of conventional degreasing apparatus.

In another process embodiment of the invention, the 15 azeotrope-like compositions of the invention may be used to form polyurethane and polyisocyanurate foams by reacting and foaming a mixture of ingredients which will react to form polyurethane and polyisocyanurate foams in the presence of a blowing agent comprising the 20 azeotrope-like compositions.

The compositions of the invention may be used as auxiliary or primary blowing agents for the preparation of polyurethane foams. Polyurethanes are polymers of polyols

25 and isocyanateε. A wide variety of polyols may be employed as disclosed in the prior art, such as polyether polyols and polyester polyols. Illustrative suitable polyether polyols are polyoxypropylene diols having a molecular weight of between about 1,500 and 2,500,

30 giycerol based polyoxypropylene triols having a molecular weight of between about 1.000 and 3,000, trimethylol- propane-based triols having a hydroxyl number of about 390. sorbitol-based hexol having a hydroxyl number of about 490, and sucrose-based octols having a hydroxyl

³⁵ number of about 410. Illustrative suitable polyester polyols are the reaction products of polyfunctional organic carboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid with monomeric polyhydric alcohols such as giycerol, ethylene glycol, trimethylol propane, and the like.

5 A wide variety of isocyanates may be employed as disclosed in the prior art. Illustrative suitable isocyanates are the aliphatic isocyanates such as hexamethylene diisocyanate, aromatic isocyanates such as toluene diisocyanate (TDI), preferably the isomeric 0 mixture containing about 80 weight percent of the 2.4 . isomer and 20 weight percent of the 2.6 isomer, crude TDI, crude diphenylmethane diisocyanate and polymethyl- polyphenyl isocyanate.

5 The amount of blowing agent to be employed will depend on whether it is to be used as a primary or auxiliary blowing agent and the nature of the foams desired, i.e. whether flexible or rigid foam is desired.

0 The amount of blowing agent employed can be readily determined by persons of ordinary skill in the art. Generally, about 1 to about 15 weight percent based on the polyurethane forming reaction mixture is employed and preferably, between about 5 to about 10 weight percent.

25

As is well known in the art, the urethane-forming reaction requires a catalyst. Any of the well known urethane-forming catalysts may be employed. Illustrative organic catalysts are the amino compounds such as

30 triethylenediamine N,N,N' .N'-tetramethylethylenediamine, dimethylethanolamine, triethylamine and N-ethyl- morpholine. Inorganic compounds such as the non-basic heavy metal compounds as illustrated by dibutyl tin dilaurate, stannous octoate and manganese acetyl acetonate

- - may also be used as catalysts. In general, the amount of catalyst present in the foam forming mixture ranges from about 0.05 to about 2 parts by weight per 100 parts by weight of the polyol component. As is well recognized in the art. a variety of other additives may be incorporated in the foam-forming mixtures including stabilizers, such as silicone oils; cross-linking agents such as 1,4-butanediol, giycerol, 5 triethanolamine methylenedianiline; plasticizers, such as tricresyl phosphate and dioctyl phthalate; antioxidants; flame retardants; coloring material; fillers; and antiscorch agents.

0 Polyurethane foams are prepared according to the invention by reacting and foaming a mixture of ingredients which will react to form the foams in the presence of a blowing agent according to the invention. In practice, the foam forming ingredients are blended, allowed to foam, 5 and are then cured to a finished product. The foaming and curing reactions, and conditions therefor are well-known- in the art and do not form a part of this invention. Such are more fully described in the prior art relating to the manufacture of polyurethane foams. Thus, for example, the 0 polyether may first be converted to a polyether- polyisocyanate prepolymer by reaction in one or more stages with an excess amount of isocyanate at temperatures from about 75°-125°C. or by reacting the polyol and the isocyanate together at room temperature in the presence of 5 a catalyst for the reaction such as N-methylmorpholine. The prepolymer would then be charged to the foam-forming mixture as the foam producing ingredient with or without the addition of additional isocyanate and foamed in the presence of the blowing agent, optionally with additional

30 polyol cross-linking agents and other conventional optional additives. Heat may be applied to cure the foam. If a prepolymer is not employed, the polyether, isocyanate, blowing agent and other optional additives may be reacted simultaneously to produce the foam in a single

- ~ stage. A premix of the polyol and present blowing agent may also be used. This premix has enhanced stability due to the present blowing agent composition of HCFC-141b and dichlorotrifluoroethane.

The HCFC-141b and dichlorotrifluoroethane components of the novel solvent azeotrope-like compositions of the invention are known materials. Preferably, except for "commercial HCFC-123" and its impurities, the materials should be used in sufficiently high purity so as to avoid the introduction of adverse influences upon the desired properties or constant boiling properties of the system.

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 1-5

These examples confirm the existence of constant- boiling or azeotrope-like compositions of 1.1-dichloro- 0 l-fluoroethane and HCFC-123 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 and commercially available ultra-pure HCFC-123 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 2:1 was employed for this particular distillation. 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.

TABLE I

Starting Mater: Lai (wt. %)

Example HCFC-141b HCFC-123

1 98.9 1.1

2 94.7 5.3

3 60.2 39.8 4 30.2 69.8

5 9.9 89.1

Distillate Compositions (wt.

Example HCFC-141b HCFC-123 1 98. .7 1, .3

2 94. .5 6 .0

3 55. .8 44 .2

4 27. .2 72 .8

5 7. .4 92 .6

Boiling Point Boiling Barometric Corrected to

Example Point (°C) Pressure(mmHq) (kPa) 760mmHq(101kPa)

1 31.3 742(99) 32.0

2 30.5 742(99) 31.2 3 30.6 742(99) 31.3 4 31.3 749(100) 31.7 5 28.7 749(100) 29.1

Mean 31.0 + 1.4 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 6

This example shows that boiling point remains essentially constant in the boiling point vs. composition curve in the region of 99.5 to 94.5 weight percent 1,l-dichloro-l-fluoroethane and from 0.5 to 5.5 weight percent 1,2-dichloro-l,1,2-trifluoroethane indicating that a constant-boiling blend is formed in this composition range.

The temperature of boiling liquid mixtures was measured using comparative ebulliometry in essentially the same manner as described by W. Swietoslawski in Ebulliometric Measurements, p. 14, Reinhold Publishing Corp.. (1945). Two ebulliometers. each charged with measured quantities of 1,l-dichloro-l-fluoroethane, were used in the present example.^' The ebulliometers were interconnected via a large ballast volume, in which the pressure was maintained to within +.0.05 mm Hg using a supply of dry air controlled with a solenoid valve and an electronic pressure transducer. Precise pressure control is necessary for accurate boiling point determinations. Each ebulliometer consisted of an electrically heated sump in which the 1,l-dichloro-l-fluoroethane was brought to boil. A condenser was connected to this sump and the system was operated under total reflux. Slugs of boiling liquid and vapor were pumped from the sump, via a Cottrell pump, over a thermowell. which contained a calibrated thermistor used for precise temperature measurements. After bringing the 1,l-dichloro-l-fluoro¬ ethane to boil under controlled pressure, measured amounts of 1,2-dichloro-l,1.2-trifluoroethane were titrated into one of the ebulliometers. The change in boiling point was measured with reference to the other ebulliometer, which still contained only 1.l-dichloro-l-fluoroethane.

Temperature and pressure measurements, as well as the measured titration, were all performed automatically with the aid of a computerized data acquisition system. Boiling point measurements were performed at two pressures, generally in the region of 760 mm Hg (101 kPa) and 765 mm Hg (102 kPa). for each composition. These measurements were corrected to exactly 760 mm Hg (101 kPa) and 765 mm Hg (102 kPa) by applying a small, measured, linear correction. Such boiling point measurements are believed accurate to +.0.002°C.

The following Table II shows the boiling point measurements, corrected to 760 mm Hg (101 kPa), for various mixtures of 1,l-dichloro-l-fluoroethane and 1,2- dichloro-1.1,2-trifluoroethane. Over the entire region shown in Table II, the boiling point of the composition has changed by only 0.04°C. Therefore, the composition behaves as a constant-boiling composition over this range. TABLE I I

Liquid Mixture

Parts by weight % Parts by weight % 1,1-dichloro-l- 1,2-dichloro-l.1,2- Boiling Point fluoroethane trifluoroethane @760mmHg(101kPa)

100 0 32.040

99.86 0.14 32.035 99.57 0.43 32.030 98.87 1.13 32.019 97.49 2.51 32.000

EXAMPLE 7

Example 6 was repeated in the ebulliometer except that 1, l-dichloro-l-fluoroethane was added to 1,2-dichloro- 1,1,2-trifluoroethane. The results are shown in Table III. The results show that over a range of 0.1 to 27.3% 1,1- dichloro-1-fluoroethane and 99.9 to 72.7% 1,2-dichloro- 1,1,2-trifluoroethane, the blend is essentially constant- boiling because the boiling point has changed by only 0.25°C.

TABLE III

Liquid Mixture

parts by weight Parts by weight Boiling Point(°C)

HCFC-141b HCFC-123a @760τπmHR(101kPa)

0.00 100.00 29.932

0.10 99.90 29.932 0.30 99.70 29.941

0.81 99.19 29.958

1.80 98.20 29.981

3.73 96.27 30.026 Parts by weight Parts by weight Boiling Point(°C)

HCFC-l41b HCFC-123a @76θmmHα(101kPa)

5.59 94.41 30.063

7.37 92.63 30.123

9.09 80.91 30.167

10.74 89.26 30.217

12.34 87.66 30.267

13.88 86.12 30.305

15.37 84.63 30.351

16.81 83.19 30.392

18.20 81.80 30.429

20.19 79.81 30.489

22.10 77.90 30.541

23.91 76.09 30.593

25.65 74.35 30.642

27.30 72.70 30.688

EXAMPLE 8

Example 6 was repeated in the ebulliometer except that l,l-dichloro-2,2,2-trifluoroethane was used instead of 1,2-dichloro-l,1,2-trifluoroethane. The results are shown in Table IV. The results show that over a range of 0.14 to 34.5 weight percent l,l-dichloro-2,2,2-trifluoro¬ ethane and 99.86 to 65.5 weight percent 1,1-dichloro-l- fluoroethane, the blend is essentially constant-boiling because the boiling point has changed by only 0.7^βC.

TABLE IV

Liquid Mixture

Parts by weight Parts by weight Boiling

Point(°C)

HCFC-141b HCFC-123 @760mmHg(101kPa)

100.00 0.00 32.040 99.86 0.14 32.025 arts by weight Parts by we Boiling Point(°C)

HCFC-141b HCFC-123 (3760mmHq(101kPa)

99.58 0.42 32.017

98.87 1.13 32.015

97.49 2.51 31.987

94.85 5.15 31.957

92.34 7.66 31.936

90.00 10.00 31.912

87.71 12.29 31.880

85.57 14.43 31.859

83.52 16.48 31.817

81.57 18.43 31.794

79.71 20.29 31.748

77.94 22.06 31.726

76.24 23.76 31.685

73.82 26.18 31.595

71.56 28.44 31.536

69.43 30.57 31.452

67.42 32.58 31.390

65.53 34.47 31.320

EXAMPLE 9

Example 7 was repeated in the ebulliometer except that l,l-dichloro-2,2,2-trifluoroethane was used instead of 1,2-dichloro-l,1,2-trifluoroethane. The results are shown in Table V. The results show that over a range of 0.10 to 27.48 weight percent 1,l-dichloro-l-fluoroethane and 99.90 to 72.52 weight percent l,l-dichloro-2,2,2-tri- fluoroethane, the blend is essentially constant-boiling because the boiling point has changed by only 1.6^βC. TABLE V

Liquid Mixture

Parts by weight Parts by weight Boiling Point(°C) HCFC-141b HCFC-123 @760mmHR(101kPa)

0.00 100.00 27.8*5

0.10 99.90 27.875

0.31 99.69 27.894

0.81 99.19 27.930

1.81 98.19 27.980

3.75 96.25 28.064

5.62 94.38 28.136

7.41 92.59 28.258

9.14 90.86 28.372

10.80 89.20 28.468

12.41 87.59 28.566

13.96 86.04 28.658

15.45 84.55 28.745

16.89 83.11 28.824

18.29 81.71 28.911

20.30 79.70 29.018

22.20 77.80 29.140

24.03 75.97 29.237

25.76 74.24 29.341

27.42 72.58 29.430

EXAMPLE 10

To illustrate the constant-boiling nature of the mixtures of this invention under conditions of actual use in a vapor phase degreasing operation, a vapor phase degreas ing machine was charged with a preferred mixture in accordance with the invention, comprising about 87.2 weight percent of HCFC-141b and about 12.8 weight percent of commercially available ultra-pure HCFC-123 . The mixture was evaluated for its constant-boiling or non-segregating characteristics. The vapor phase degreasing machine utilized was a small water-cooled, three-sump vapor phase degreaser which represents a type of system configuration comparable to machine types in the field today which would present the most rigorous test of solvent segregating behavior. Specifically, the degreaser employed to demonstrate the invention contained two overflowing rinse-sumps and a boil-sump. The boil-sump and the still were electrically heated, and each contained a low-level shut-off switch. Solvent vapors in both the degreaser and the still were condensed on water-cooled stainless-steel coils. The still was fed by gravity from the boil-sump. Condensate from the still was returned to the first rinse-sump, also by gravity. The capacity of the unit was approximately 1.5 gallons. This degreaser was very similar to Baron Blakeslee 2 LLV 3-sump degreasers which are quite commonly used in commercial establishments.

The solvent charge was brought to reflux and the compositions in the condensate sump containing the clear condensate from the still, the work sump containing the overflow from the condensate sump, the boil sump where the overflow from the work sump is brought to the mixture boiling points, and the still were determined with a

Perkin Elmer 8500 gas chromatograph. The temperature of the liquid in all the sumps was monitored with thermocouple temperature sensing devices accurate to +. 0.2°C. Refluxing was continued for about 30 hours and boil and condensate sump compositions were monitored throughout this time. A mixture was considered constant-boiling or non-segregating if the maximum concentration difference between sumps for any mixture component was ± 2 slg a around the mean value. Sigma is -. a standard deviation unit and it is our experience from many observations of vapor degreaser performance that commercial "azeotrope-like" vapor phase degreasing solvents exhibit at least a ± 2 sigma variation in composition with time and yet produce very satisfactory non-segregating cleaning behavior.

If the mixture were not azeotrope-like, the high boiling components would very quickly concentrate in the still and be depleted in the rinse sump. This did not happen. Also, the concentration of each component in the sumps stayed well within +.2 sigma. These results indicate that the compositions of this invention will not segregate in any type of large-scale commercial vapor degreasers, thereby avoiding potential safety, performance, and handling problems. The preferred composition tested was also found to not have a flash point according to recommended procedure ASTM D 1310-86 (Tag Open Cup). The compositions in the sumps are shown in Table VI below.

TABLE VI

Degreaser Composition Stability Study

Condensate Sump

Initial Composition 17 hour 30 hour HCFC-141b 87.2 86.7 87.0 HCFC-123 12.8 13.3 13.0 Temperature (°C) 19.3 22.3 Barometric Pressure (mm of Hg) (k Pa) 754(100) 748(99)

Boil Sump

Initial Composition 17 hour 30 hour

HCFC-141b 87.2 88.8 88.9 HCFC-123 12.8 11.2 11.1

Temperature (°C) 31.6 31.4 Barometric Pressure (mm of Hg)(k Pa) 754(100) 748(99) EXAMPLE 11

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.

EXAMPLE 12

Example 6 is repeated except that a mixture of

1.l-dichloro-2.2.2-trifluoroethane and 1,2-dichloro-l.1,2- trifluoroethane is used.

EXAMPLE 13

Performance studies were conducted wherein metal coupons were cleaned using the present azeotrope-like compositions as solvents. The metal coupons were soiled with various types of oils and heated to 93°C so as to partially simulate the temperature attained while machining and grinding in the presence of these oils.

The metal coupons thus treated were degreased in a three-sump vapor phase degreaser machine. In this typical three-sump degreaser, condenser coils around the lip of the machine are used to condense the solvent vapor which is then collected in a sump. The condensate overflows into cascading sumps and eventually goes into the boiling sump.

The metal coupons were held in the solvent vapor and then vapor rinsed for a period of 15 seconds to 2 minutes depending upon the oils selected. A short time period was selected so that the solvents could be easily compared. The present azeotrope-like compositions were compared with 1.1.2-trichloro-l.2,2-trifluoroethane (known in the art as CFC-113) in cleaning performance because CFC-113 is commonly used in degreasing systems. In comparing the performances of the solvents, cleanliness testing of coupons was done by measurement of the weight change of the coupons using an analytical balance to determine the total residual materials left after cleaning. The cleanliness test results are shown below in Table VII. The results show that the present azeotrope-like compositions of 80 percent by weight 1. l-dichloro-l-fluoroethane and 20 percent by weight 1. l-dichloro-2,2.2-trifluoroethane performed equal to or better than CFC-113 in cleaning the various oils. The cleaning results are shown in percentage of oils removed from the surfaces.

TABLE VII

OIL SOLVENT % OIL REMOVED

Petroleum Based CFC-113 99.1 + 0.4 Petroleum Based HCFC-141b/HCFC-123 98.3 + 0.8

Semi-synthetic CFC-113 87.8 + 1.3 Semi-synthetic HCFC-141b/HCFC-123 99.9 + 0.3

Synthetic CFC-113 19.0 + 8.0 Synthetic HCFC-141b/HCFC-123 54.4 + 7.9

EXAMPLES 14-15

Example 14 describes the properties of rigid polyurethane foam prepared using a 33/67 blend of commercially available ultra-pure HCFC-123/HCFC-141b while Example 15 describes the properties of rigid polyurethane foam prepared using a 67/33 blend of commercially available ultra-pure HCFC-123/HCFC-141b. Free-rise rigid polyurethane foams were prepared from the formulations specified in Table VIII using a Martin Sweets Co. Modern Module III urethane foam machine at a delivery rate of 15 lbs./min. This polyurethane formulation is one example of a pour-in-place rigid polyurethane formulation which might be used as an appliance insulation.

The foams were characterized (Table IX) according to initial density, thermal conductivity (K-factor), dimensional stability, porosity (% open-cells), compression, and reactivity.

TABLE VIII

Rigid Polyurethane Formulation

Parts by Weight

Component Example 14 Example 15 Pluracol 1114¹ (420-OH#) 100. 100.

2 Silicone L-5340 1.5 1.5

3 Thancat TD-33 0.5 0.5

4 Thancat DME 0.2 0.2

Catalyst T-12 0.1 0.1 HCFC-123/HCFC-141b(33/67) 33.24

HCFC-123/HCFC-141b(67/33) 37.71

Lupranate M20S (1.29 Index) 129 129

BASF Wyandotte Corp. - polyether polyol

Union Carbide Corp. - silicone surfactant

I Texaco Inc. - 33% tπethylene diamine in propylene glycol

Texaco Inc. - N,N-dimethylethanolamine

Metal & Thermit Co. - dibutyl dilaurate

BASF Wyandotte Corp. - polymethylene polyphenylisocyanate TABLE IX

Rigid Urethane Foam Properties

Example 14 Example 15

Physical Properties

Density (lb/cu.ft.) 2.167 2.047 K-factor* 0.165 0.154 (Btu in/hr ft² °F)

Dimensional Stability* % Vol. Change (-40°C. 24 hr) 0.089 0.224 % Vol. Change (70°C. 16 hr) -1.13 -1.72 Porosity (% Open-Cells) 7.25 7.57

Compression (PSI)

Parallel to rising foam 12.30 22.9 Perpendicular to Rising Foam 5.73 14.2

Reactivity

Cream Time (sec) 16.0 15.0 Gel Time (sec) 28.0 26.0 Tack Free Time (sec) 41.0 37.0

*5 day old foam

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 effective amounts of 1,l-dichloro-l-fluoroethane and dichlorotrifluoroethane.

2. The azeotrope-like compositions of claim 1 comprising from about 0.5 to about 99.5 weight percent said 1,l-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent 1,l-dichloro-2,2,2-trifluoroethane.

3. The azeotrope-like compositions of claim 1 comprising said 1,l-dichloro-l-fluoroethane and

1,l-dichloro-2,2,2-trifluoroethane which boil at about 29;9°C +. about 2.1°C at 760 mm Hg.

4. The azeotrope-like compositions of claim 1 comprising from about 50 to about 99.5 weight percent said 1,l-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent 1,l-dichloro-2.2,2-trifluoroethane which boil at about 31.2°C + about 0.8°C at 760 mm Hg.

5. The azeotrope-like compositions of claim 1 comprising from about 50 to about 69.6 weight percent said 1,l-dichloro-l-fluoroethane and from about 30.4 to about 50 weight percent l.l-dichloro-2.2,2-trifluoroethane.

6. The azeotrope-like compositions of claim 1 comprising from about 0.5 to about 99.5 weight percent said 1.l-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent 1,2-dichloro-l.1,2-trifluoroethane.

7. The azeotrope-like compositions of claim 1 comprising said 1.l-dichloro-l-fluoroethane and

1,2-dichloro-l.1,2-trifluoroethane which boil at about 31.1°C ± about 1.0°C at 760 mm Hg.

8. The azeotrope-like compositions of claim 1 comprising from about 50 to about 99.5 weight percent said 1,l-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent 1.2-dichloro-l.1,2-trifluoroethane which boil at about 31.5°C ± about 0.5°C at 760 mm Hg.

9. The azeotrope-like compositions of claim 1 comprising from about 0.5 to about 99.5 weight percent of said 1.l-dichloro-l-fluoroethane and from about 0.5 to about 99.5 weight percent of a mixture of

1.l-dichloro-2,2,2-trifluoroethane and 1,2-dichloro-l,1.2-trifluoroethane.

10. The azeotrope-like compositions of claim 1 comprising said 1,l-dichloro-l-fluoroethane and a mixture of 1,1-dichloro-2,2.2-trifluoroethane and

1.2-dichloro-l,1,2-trifluoroethane which boil at about 30.0°C about 2.0°C at 760 mm Hg.

11. The azeotrope-like compositions of claim 1 comprising from about 50 to about 99.5 weight percent of said 1,l-dichloro-l-fluoroethane and from about 0.5 to about 50 weight percent of a mixture of

1,1-dichlo 0-2.2,2-trifluoroethane and

1,2-dichloro-l,1,2-trifluoroethane which boil at about 31.3°C about 0.7°C at 760 mm Hg.

12. A method of cleaning a solid surface which comprises treating said surface with said azeotrope-like composition as defined in claim 2.

13. A method of cleaning a solid surface which comprises treating said surface with said azeotrope-like composition as defined in claim 6.

14. A method for preparing polyurethane and polyisocyanurate foams which comprises reacting and foaming a mixture of ingredients which will react to form the polyurethane or polyisocyanurate foams in the presence of a blowing agent comprising the azeotrope-like composition of claim 5.