Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2003-06-04
2004-09-07
Cooney, John M. (Department: 1711)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S412000, C510S415000
Reexamination Certificate
active
06787513
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to azeotrope-like compositions of pentafluoropropane and chloropropane, to methods of using such compositions, and to blown foams formed using such compositions.
BACKGROUND
Fluorocarbon based fluids have found widespread use in industry in a number of applications, including, as refrigerants, aerosol propellants, blowing agents, blowing agents, heat transfer media, and gaseous dielectrics. Because of the suspected environmental problem associated with the use of some of these fluids, especially chlorofluorocarbons (“CFCs”), it is desirable to use fluids of lesser ozone depletion potential such as hydrofluorocabons (“HFCs”) and/or hydochlorofluorocaborns (“HCFCs).
Thus, the use of fluids that do not contain CFCs or contain HCFCs or HFCs instead of CFCs 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 in many application, including as blowing agents in the production of foams. For example, low-density rigid foams, such as polyurethane and polyisocyanurate foams, are used in a wide variety of applications including insulation for roofing systems, building panels, refrigerators and freezers. To be useful in such applications, it is critical for the foams to exhibit, among other properties, relatively high thermal insulation. One measure of a foam's thermal insulation properties is its “k-factor”. The term “k-factor” refers generally to the rate of transfer of heat energy by conduction through one square foot of one inch thick homogenous material in one hour where there is a difference of one degree Fahrenheit perpendicularly across the two surfaces of the material. Since the utility of many closed-cell foams is based, at least in part, upon their thermal insulation properties, it is advantageous and desirable to produce rigid foams having low k-factors.
Known methods for producing rigid foams generally comprise an organic polyisocyanurate and a polyol in the presence of a blowing agent to form a rigid foam See, for example, Saunders and Frisch, Volumes I and II Polyurethanes Chemistry and Technology (1962), which is incorporated herein by reference. While the thermal properties of foams produced by these conventional methods may be adequate for selected applications, there is a constant need in the art to identify methods for producing foams having k-factors at least as low or lower than the produced via conventional methods.
However, the identification of new, environmentally safe, azeotropic mixtures, particularly those well suited for use as blowing agents, is complicated due to the fact that azeotrope formation is not readily predictable.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present inventors have developed compositions that can help to satisfy the continuing need for substitutes for CFCs and HCFCS. In one embodiment, the present invention provides azeotrope-like compositions comprising 1,1,1,3,3-pentafluoropropane (“HFC-245fa”) and 2-chloropaae.
The preferred compositions of the invention provide environmentally desirable replacements for curently used CFC's and HCFC's. Additionally, the compositions of the invention exhibit characteristics that make the compositions better CFC and HCFC substitutes than either or 1,1,1,3.3-pentafluoropropane or 2-chloropropane alone.
One aspect of the invention provides a method for producing foams, preferably foams with relatively low k-factors. Applicants have discovered that foam blowing agents which comprise the compositions of the present invention are unexpectedly capable of providing foams and methods for producing foams with substantial advantage over prior foams and processes. More particularly, applicants have counter-intuitively discovered that the use of compositions comprising chloropropane and HFC-245fa as a blowing agent produces foam cells that have a higher percentage of HFC-245 in the cell gas than when HFC-245fa is used alone as the blowing agent. This aspect of the present intention can be an advantage in certain embodiments, especially those requiring a foam with improved flammability resistance and/or thermal properties. This is because HFC 245fa is less flammable than and/or has thermal properties superior to many of the other ingredients in the foamable composition, including alternative blowing the agents. In preferred embodiments, the present invention provides blowing agent comprising, and preferably consisting of, from about 20 wt % to about 80 wt % HFC-245fa and from about 20 wt % to about 80 wt % of 2-chloropropoane, and even more preferably from about 25 wt % to about 75 wt % HFC-245fa and from about 25 wt % to 75 wt % of 2-chloropropoane.
The blowing agent aspects of the invention do not necessarily require that the HFC-245fa/2-chloropropane is present in the form of an azeotrope-like composition. It is contemplated, however, that the preferred blowing agents of the present invention will comprise azeotrope-like compositions of pentafluoropropane and chloropropane.
The preferred foams of the present invention preferably have closed cells containing gas comprising HFC-245fa in a concentration that is at least about 1.5 times, and even more preferably at least about 2 times, the concentration of HFC-245fa in the foamable composition used to form the foam. In certain preferred embodiments, the foams of the present invention have closed cells containing contain gas comprising HFC-245fa in a concentration that is greater than 3 times the concentration of HFC-245fa in the blowing agent used.
Preferred forms to the present invention also exhibit the ability of inhibiting undesirable decomposition during the foaming reaction.
Another aspect of the present invention is a closed-cell foam produced according to the methods of the present invention.
Another aspect of the present invention is the provision of azeotrope-like compositions. As used herein, the term azeotrope-like is intended in its broad sense to include both compositions that are strictly azeotropic and compositions that behave like azeotropic mixtures. From fundamental principles, the thermodynamic state of & 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 ozeotropic mixture are constant boiling and cannot be separated during a phase change.
As the term is used herein, “ezeotrope-like” compositions behave like azeotropic mixtures, that is, they 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 azetropic 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 azeotopic 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 non-azeotrope mixture into its separate components. If the mixture containing the additional component
Bement Leslie
Bogdan Mary C.
Knopeck Gary
Pham Hang T.
Riegal Ronald
Cooney John M.
Honeywell International , Inc.
Szuch Colleen D.
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