Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Having discontinuous gas or vapor phase – e.g. – foam:
Reexamination Certificate
2002-11-01
2003-07-29
Foelak, Morton (Department: 1711)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Having discontinuous gas or vapor phase, e.g., foam:
C516S018000, C521S088000, C521S097000, C521S098000
Reexamination Certificate
active
06599946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to blowing agent compositions containing carbon dioxide (CO
2
) and a normally-liquid hydrofluorocarbon (HFC), foamable polymer compositions comprising a polymer and such blowing agent compositions, the use of such compositions for preparing polymeric foam, and polymeric foam containing residuals of the blowing agent composition. A normally-liquid HFC has a boiling point of 14° C. or higher, preferably 30° C. or higher, and lower than about 120° C. at one atmosphere of pressure.
2. Description of Related Art
CO
2
is an attractive blowing agent for preparing polymeric foam because it does not contribute to volatile organic compound (VOC) emissions and poses little, if any, risk to the Earth's ozone layer. However, as a sole blowing agent, CO
2
tends to produce polymeric foam having a higher percentage of open cells, smaller cell sizes, and a higher thermal conductivity than is desirable, particularly for thermal insulating applications. Furthermore, polymeric foams having infrared blockers such as carbon black are difficult to make using only CO
2
as a blowing agent.
Hydrofluorocarbons (HFCs) are also attractive blowing agent components, particularly for preparing thermally insulating polymeric foams. HFCs are increasingly attractive as replacements for hydrochlorofluorocarbons (HCFCS) and chlorofluorocarbons (CFCs), which can contribute to ozone depletion. As with CO
2
, HFCs pose little, if any, risk to the Earth's ozone layer. Furthermore, HFCs have a thermal conductivity lower than most polymers or blowing agents (other than HCFCs and CFCs) so HFC residuals in a polymeric foam can lower the foam's thermal conductivity.
Typically, HFCs in blowing agent compositions have a boiling point of 14° C. or less (HFC(g)). Unfortunately, HFC(g)s permeate out of polymeric foam and escape into the atmosphere, which can result in both an increase in the foam thermal conductivity and organic emissions.
A need exists in the art of blowing agents for a composition that is safe for the environment and produces thermally insulating polymeric foam. Preferably, the composition contains a HFC that remains in polymeric foam longer than HFC(g)s thereby slowing or reducing thermal conductivity increases and organic emission levels experienced when using HFC(g)s. More preferably, the composition comprises CO
2
and a HFC that at least partially compensates for CO
2
deficiencies.
DEFINITIONS
“Hydrofluorocarbon” and “HFC” are interchangeable terms and refer to an organic compound containing hydrogen, carbon, and fluorine. The compound is substantially free of halogens other than fluorine.
“Boiling point” refers to the boiling point at one atmosphere pressure.
“Normally-gaseous material” refers to a material that has a boiling point lower than 14° C.
“Normally-liquid hydrofluorocarbon”, “normally-liquid HFC”, and “HFC(l)” are interchangeable terms and refer to a HFC that has a boiling point of 14° C. or higher and lower than about 120° C.
“Normally-gaseous hydrofluorocarbon”, “normally-gaseous HFC”, and “HFC(g)” are interchangeable terms and refer to a HFC that has a boiling point lower than 14° C.
“Low-boiling alcohol” and “LBA” are interchangeable terms and refer to an alcohol having a boiling point lower than about 120° C.
“Low-boiling carbonyl compound” and “LBC” are interchangeable terms and refer to an aldehyde or a ketone having a boiling point lower than about 120° C.
“Low-boiling hydrocarbons” and “LBHs” are interchangeable terms and refer to hydrocarbons having a boiling point lower than 55° C., including halogenated hydrocarbons.
“Low-boiling ethers” and “LBEs” are interchangeable terms and refer to ethers having a boiling point lower than 55° C., including halogenated ethers.
“Fresh” refers to within one month, preferably within one week, more preferably within one day, still more preferably within one hour, most preferably immediately after manufacture.
A polymeric foam or blowing agent composition that is “essentially free” of a specified component or components refers, respectively, to a polymeric foam or blowing agent composition that contains ten weight-percent (wt %) or less, preferably five wt % or less, more preferably one wt % or less, still more preferably 0.5 wt % or less, most preferably zero wt % of the specified component(s) based, respectively, on foam or blowing agent composition weight.
A blowing agent composition “consisting essentially of” a specified component or components is free from any unspecified components at concentrations that modify how the composition performs in preparing polymeric foam. Commonly, a blowing agent composition “consisting essentially of” a specified component or components refers to a composition that contains 90 wt % or more, preferably 95 wt % or more, more preferably 99 wt % or more, still more preferably 99.5 wt % or more, most preferably 100 wt % of the specified component(s). Wt % is relative to weight of blowing agent composition.
BRIEF SUMMARY OF THE INVENTION
In a first aspect, the present invention is a blowing agent composition comprising: (a) carbon dioxide; and (b) at least one hydrofluorocarbon having a boiling point of 30° C. or higher and lower than about 120° C.; said composition being essentially free of low-boiling ethers and low-boiling hydrocarbons other than (b). 1,1,1,3,3-pentafluorobutane is a preferred hydrofluorocarbon in the first aspect.
In a second aspect, the present invention is a blowing agent composition comprising: (a) carbon dioxide; and (b) at least one hydrofluorocarbon having a boiling point of 14° C. or higher and lower than about 120° C.; wherein greater than 50 weight-percent of the composition is carbon dioxide and wherein a sufficient amount of (b) is present to produce a polymeric foam having an improved skin quality, lower open cell content (according to ASTM method D-6226), larger average cell size, improved skin quality, or any combination thereof relative to the same foam prepared using only carbon dioxide as a blowing agent. Preferably, at least one hydrocarbon in (b) of the second aspect is 1,1,1,3,3-pentafluorobutane.
One preferred embodiment of the second aspect further comprises: (c) at least one hydrofluorocarbon having a boiling point lower than 14° C.; and (d) at least one additional blowing agent selected from water, alcohols, ketones and aldehydes; said alcohols, ketones and aldehydes having a boiling point lower than about 120° C. at atmospheric pressure.
The first and second aspects of the invention can further comprise additional blowing agents selected from water and alcohols having a boiling point lower than about 120° C, particularly ethanol.
In a third aspect, the present invention is a blowing agent composition consisting essentially of carbon dioxide and one hydrofluorocarbon having a boiling point of 14° C. or higher and lower than about 120° C. Carbon dioxide is preferably liquefied in each of the embodiments of the first three aspects.
In a fourth aspect, the present invention is a process for preparing polymeric foam comprising expanding a foamable polymer composition in a process suitable for forming a polymeric foam using a blowing agent composition selected from a group consisting of the blowing agent compositions of the first three aspects.
In a fifth aspect, the present invention is a polymeric foam comprising: (a) a polymer having cells defined therein; (b) carbon dioxide; and (c) at least one hydrofluorocarbon having a boiling point of 30° C. or higher and lower than about 120° C.; wherein at least a portion of (b) and (c) resides in said cells and said polymeric foam is essentially free of any low-boiling ethers or low-boiling hydrocarbons other than the hydrofluorocarbon (c).
In a sixth aspect, the present invention is a polymeric foam comprising: (a) a polymer having cells defined therein; (b) carbon dioxide; (c) at least one hydrofluorocarbon having a boiling point of 14° C. or higher and lower than about 120° C.; (d) at least one hydrofluorocarbon having a boil
Duffy John D.
Griffin Warren H.
Foelak Morton
Mork Steven W.
The Dow Chemical Company
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