Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2002-06-03
2004-09-14
Cooney, John M (Department: 1711)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C062S114000, C134S010000, C134S021000, C134S022120, C134S022140, C134S042000, C252S182240, C252S182270, C510S408000, C510S412000, C510S415000, C521S050000, C521S117000, C521S131000, C521S170000
Reexamination Certificate
active
06790820
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to compositions comprising a hydrofluorocarbon (“HFC”) component and a non-HFC component. More specifically, the present invention relates to ranges of HFC/trans-1,2-dichloroethylene compositions having boiling points that are unexpectedly low and relatively constant, and uses thereof.
BACKGROUND
Hydrofluorocarbon-based compositions are of interest for use as replacements for chlorofluorocarbon (“CFC”) and/or hydrochlorofluorocarbon (“HCFC”) compositions, which tend to be environmentally undesirable. In particular, applicants have recognized that compositions comprising mixtures of hydrofluorocarbon (“HFC”) are of interest for use in a wide range of applications, including for use as propellants in aerosol or other sprayable compositions. Unfortunately, applicants have identified a number of disadvantages associated with adapting HFCs for use in aerosols.
One such disadvantage is an HFC's insolubility with many of the lubricants used commonly in refrigeration and spraying applications. Applicants recognize, however, that mixing the HFC with certain non-HFCs solublizing agents can improve the composition's solubility with such lubricants. In such embodiments, it is highly advantageous, if not necessary, for HFC
on-HFC compositions to be soluble with lubricants which are used in conventional CFC applications such as CASTROL SW2 Polyol ester refrigerant oil and LUBRIKUHL 130 ESTER Polyol ester refrigerant oil.
Although mixing an HFC with a particular non-HFC tends to improve its solubility, the introduction of the particular non-HFC also tends to have negative consequences. First, the non-HFC increases the flammability of the composition. Applicants have come to appreciate that solubility and flammability are often competing requirements since components of a composition which tend to increase solubility with lubricants oils also tend to increase the flammability of such compounds. Therefore, there is a need for HFC
on-HFC mixtures that are not only sufficiently soluble in conventional lubricants, but also are relatively non-flammable.
In addition to flammability, the non-HFC component tends to increase the sensitivity of the composition's boiling point to compositional changes. Conventional aerosol cans and other sprayers known in the art are designed to work with fluids having a specific vapor pressure and boiling point. If the vapor pressure/boiling point characteristics of a fluid to be sprayed are different from the specific characteristics for which the sprayer has been designed, the sprayer will not work. For example, in certain cases, a sprayer designed to work with a composition of having a boiling point of 50° C., will often not work with a composition having a boiling point that differs by as little as 1° C. or more.
Unfortunately, as is known in the art, the combination of two or more constituents to form an HFC
on-HFC composition often results in compositions wherein relatively small changes in the relative concentrations of the components result in relatively large changes in boiling point and vapor pressure. For example, if a non-HFC has a higher boiling point than the HFC (which is likely when the non-HFC is a solublizing agent), then it is generally understood that the boiling point of the HFC
on-HFC composition will increase as the concentration of the non-HFC component is increased. This increase in boiling can be significant, especially if the non-HFC component has a high boiling point. Accordingly, relatively small changes in the relative concentration of components in a composition may have a relatively large effect on the composition's boiling point. As mentioned above, spraying and refrigeration apparatus are generally intolerant of changes in the boiling point of the compositions used therewith.
In light of the above, applicants recognize that HFC mixtures having a relatively constant boiling point, that is, a boiling point which changes by a relatively small amount as the relative concentrations of the components change, are desirable. Specifically, a relatively constant boiling point/vapor pressure, would facilitate the use of a wide range of compositions with relatively few number of spraying devices. Unfortunately, HFC
on-HFC mixtures having such relatively constant boiling point properties are uncommon and unpredictable.
Therefore, there is a need for a HFC mixture which is soluble with lubricants while being non-flammable and having a relatively constant boiling point across a range of varying constituent concentrations. The present invention fulfills this need among others.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
The present invention overcomes the aforementioned shortcomings by providing for HFC compositions that are not only soluble in conventional lubricants, but also exhibit a relatively constant boiling point and are non-flammable. Specifically, the applicants have identified a composition comprising an HFC component, namely a mixture of 1,1,1,3,3-pentafluorobutane (“HFC-365mfc”) and 1,1,1,3,3-pentafluoropropane (“HFC-245fa”), and a non-HFC solublizing agent, namely, trans-1,2-dichloroethylene (“Trans”).
This composition has a remarkably steady boiling point with respect to compositional changes and even displays “quasi-azeotropic” characteristics. As used herein, the term “quasi-azeotropic” refers to a characteristic of a mixture in which its boiling point falls outside the highest and lowest boiling points of the composition's HFC component and non-HFC component. In the present invention, the composition has a boiling point which is below the boiling point of both the HFC component (i.e. the mixture of HFC-365mfc and HFC-245fa) and the non-HFC component (i.e., the Trans). This is surprising, especially when one considers the fact that the boiling point of Trans is well above the boiling points of either HFC-365mfc or HFC-245fa. It should be understood that even though the composition of the present invention has a boiling point below the HFC component, it does not necessarily have a boiling point below each of the HFCs in the HFC component (i.e., HFC-365mfc and HFC-245fa individually). Indeed, in this case, the composition does not have a boiling point below HFC-245fa--hence, its characterization as a quasi-azeotrope rather than an azeotrope.
Without being bound or limited by any particular theory, applicants suspect that the the quasi-azeotropic characteristics of the composition tend to stabilize, to some degree, the relative concentration of the components in the composition during vaporization. More specifically, since the composition has a boiling point lower than the HFC and non-HFC components, there may be a tendency during vaporization for the relative concentration of the components to gravitate toward a particular relationship in which the composition has the lowest boiling point. At this point, vaporizing the composition should have relatively little impact on the relative concentrations of the HFC and non-HFC components—i.e., the composition will manifest azeotropic characteristics. As is well known, if the relative concentration of the components is stable during vaporization, the boiling point of the composition will be stable.
It should be understood, however, that the composition of the present invention will not behave as a true azeotrope since the HFC-245fa constituent of the HFC component has a lower boiling point than that of the composition. Accordingly, as the composition vaporizes HFC-245fa will vaporize at a higher rate and thereby change the relative concentration of the HFC component. A change in the relative concentration of the HFC component will affect the relative concentration of the HFC and non-HFC components, which, in turn, will affect the boiling point of the composition. It is suspected, however, that this affect on boiling point will be tempered in good measure by the the quasi-azeotropic characteristics of the composition.
Aside from the quasi-azeotropic chartacteristics of the composition, applicants have also
Bogdan Mary C.
Cook Kane D.
Knopeck Gary M.
Pham Hang T.
Singh Rajiv R.
Chess Deborah
Cooney John M
Honeywell International , Inc.
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