Azeotrope-like compositions of pentafluoropropane and water

Details Azeotrope-like compositions of pentafluoropropane and water Azeotrope-like compositions of pentafluoropropane and water

1999-03-15

2003-02-04

Cooney, Jr., John M. (Department: 1711)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Liquid composition

C252S364000, C510S177000, C521S131000

Reexamination Certificate

active

06514928

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to azeotrope-like compositions of 1,1,1,3,3-pentafluoropropane (“HFC-245fa”) and water (“H
2
O”). More particularly, the invention provides compositions of HFC-245fa and water that are environmentally desirable for use as refrigerants, in centrifugal chillers, aerosol propellants, metered dose inhalers, fire extinguishers, blowing agents for polymer foam, heat transfer media, solvents, and gaseous dielectrics.
BACKGROUND OF THE INVENTION
Fluorocarbon based fluids have found widespread use in industry in a number of applications, including as refrigerants, aerosol propellants, blowing agents, heat transfer media, and gaseous dielectrics. Because of the suspected environmental problems associated with the use of some of these fluids, especially chlorofluorocarbons (“CFC's”), it is desirable to use fluids of lesser ozone depletion potential such as hydrofluorocarbons, (“HFC's”) and/or hydrochlorofluorocarbons (“HCFC's”).
Thus, the use of fluids that do not contain CFC's or contain HCFC's or HFC's instead of CFC's is desirable. Additionally, it is known that the use of single component fluids or azeotropic mixtures, which mixtures do not fractionate on boiling and evaporation, is preferred. However, the identification of new, environmentally safe, azeotropic mixtures is complicated due to the fact that it is difficult to predict azeotrope formation.
The art continually is seeking new fluorocarbon based mixtures that offer alternatives, and are considered environmentally safer substitutes for CFC's and HCFC's. Of particular interest are mixtures containing a hydrofluorocarbon and a non-fluorocarbon, both of low ozone depletion potentials. Such mixtures are the subject of this invention.
DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
This invention provides azeotrope-like compositions of HFC-245fa and water. The compositions of the invention provide environmentally desirable replacements for currently used CFC's and HCFC's since HFC-245fa and water have zero ozone depletion potentials. Additionally, the compositions of the invention exhibit characteristics that make the compositions better CFC and HCFC substitutes than either HFC-245fa or water alone.
Accordingly, the invention provides azeotrope-like compositions comprising effective amounts of HFC-245fa and water. By “effective amounts” is meant the amount of each component that, on combination with the other component, results in the formation of an azeotrope-like composition. More specifically, the invention provides azeotrope-like compositions consisting essentially of HFC-245fa and water, which compositions have a boiling point of 14° C. ±2 preferably 1° C., at 760 mm Hg pressure. The preferred, more preferred, and most preferred compositions of the invention are set forth in Table 1. The numerical ranges in Table 1 are to be understood to be prefaced by the term “about”.
TABLE 1
More Preferred
Components
Preferred (wt %)
(wt %)
Most Preferred (wt %)
HFC-245fa
65-99
75-98
83-97
Water
35-1 
25-2 
17-3 
The invention further provides a method of preparing polyurethane and polyisocyanurate foam compositions comprising the step of reacting and foaming a mixture of ingredients which react to form polyurethane or polyisocyanurate foams in the presence of a blowing agent comprising and azeotrope-like composition consisting essentially of 1,1,1,3,3-pentafluoropropane and water, preferably from about 65 to about 99 weight percent HFC-245fa and from about 35 to about 1 weight percent water; more preferably from about 75 to about 98 weight percent HFC-245fa and from about 25 to about 2 weight percent water; and most preferably from about 3 to about 17 weight percent water.
In another embodiment of the invention, there is provided a blowing agent composition comprising an azeotrope-like composition consisting essentially of HFC-245fa and water. In one embodiment the invention provides a blowing agent composition comprising an azeotrope-like composition consisting essentially of HFC-245fa and water, preferably from about 65 to about 99 weight percent HFC-245fa and from about 35 to about 1 weight percent water; more preferably from about 75 to about 98 weight percent HFC-245fa and from about 25 to about 2 weight percent water; and most preferably from about 3 to about 17 weight percent water.
The invention further relates to a closed cell foam prepared from a polymer foam formulation containing a blowing agent comprising and azeotrope-like composition consisting essentially of 1,1,1,3,3-pentafluoropropane and water. In one embodiment, the invention provides a closed cell foam prepared from a polymer foam formulation containing a blowing agent comprising an azeotrope-like composition consisting essentially of HFC-245fa and water, preferably from about 65 to about 99 weight percent HFC-245fa and from about 35 to about 1 weight percent water; more preferably from about 75 to about 98 weight percent HFC-245fa and from about 25 to about 2 weight percent water; and most preferably from about 3 to about 17 weight percent water.
In another embodiment, the invention provides a closed cell foam containing a cell gas comprising a blowing agent comprising an azeotrope-like composition consisting essentially of 1,1,1,3,3-pentafluoropropane and water, preferably from about 65 to about 99 weight percent HFC-245fa and from about 35 to about 1 weight percent water; more preferably from about 75 to about 98 weight percent HFC-245fa and from about 25 to about 2 weight percent water, and most preferably from about 3 to about 17 weight percent water.
For purposes of this invention, azeotrope-like compositions are compositions that behave like azeotropic mixtures. From fundamental principles, the thermodynamic state of a fluid is defined by pressure, temperature, liquid composition, and vapor composition. An azeotropic mixture is a system of two or more components in which the liquid composition and vapor composition are equal at the state pressure and temperature. In practice, this means that the components of an azeotropic mixture are constant boiling and cannot be separated during a phase change.
Azeotrope-like compositions behave like azeotropic mixtures, i.e., are constant boiling or essentially constant boiling. In other words, for azeotrope-like compositions, the composition of the vapor formed during boiling or evaporation is identical, or substantially identical, to the original liquid composition. Thus, with boiling or evaporation, the liquid composition changes, if at all, 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. All azeotrope-like compositions of the invention within the indicated ranges as well as certain compositions outside these ranges are azeotrope-like.
The azeotrope-like compositions of the invention may include additional components that do not form new azeotropic or azeotrope-like systems, or additional components that are not in the first distillation cut. The first distillation cut is the first cut taken after the distillation column displays steady state operation under total reflux conditions. One way to determine whether the addition of a component forms a new azeotropic or azeotrope-like system so as to be outside of this invention is to distill a sample of the composition with the component under conditions that would be expected to separate a nonazeotropic mixture into its separate components. If the mixture containing the additional component is nonazeotropic or nonazeotrope-like, the additional component will fractionate from the azeotropic or azeotrope-like components. If the mixture is azeotrope-like, some finite amount of a first distillation cut will be obtained that contains all of the mixture components that is constant boiling or behaves as a single substance.
It follows from this that another characteristic of azeotrope-like compos

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