Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-05-26
2001-07-17
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S114000, C521S117000, C521S155000, C521S170000, C521S174000
Reexamination Certificate
active
06262136
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a stable foam-forming system containing a blowing agent that is a gas at ambient temperature and pressure and to a process for the production of foams from this system.
Formulations and processes for the production of foams, particularly rigid polyurethane foams, are known. In recent years, foam producers have attempted to replace the ozone depleting CFC blowing agents with more environmentally desirable blowing agents. Among the blowing agents being evaluated and developed are hydrochloro-fluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Many of these alternative blowing agents have sufficiently low boiling points that they are in the gaseous form at ambient temperature and pressure. Consequently, it has not been possible to incorporate these blowing agents into foam-forming formulations until very shortly before use without maintaining the formulation containing the blowing agent under temperature and pressure conditions that ensure the blowing agent stays in the liquid state. See, e.g., U.S. Pat. Nos. 3,541,023; 5,451,614; and 5,470,891.
In use, the gaseous blowing agent is typically added to the day tanks of the foam machine prior to foaming. The gaseous blowing agent may also be added to the “B-side” (i.e., the isocyanate-reactive component) during blending of that reaction component or it may be added as a separate, third stream from the mixhead. Blowing agent is generally included in the “B-side” of the foam-forming mixture in an amount of from about 3 to about 5% by weight.
The need to store a formulation into which blowing agent has been incorporated under controlled temperature and pressure conditions, however, increases the expense of handling and storing such formulation. It would therefore be advantageous to develop a foam-forming formulation into which a blowing agent that is a gas at ambient conditions could be incorporated and could subsequently be stored for some period of time at ambient temperature and pressure.
U.S. Pat. No. 4,972,003 teaches that use of an isocyanate-reactive compound having an equivalent weight of greater than 140 promotes the solubility of HCFC and HFC blowing agents having boiling points below 272° K. This patent does not, however, teach that the disclosed mixtures of isocyanate-reactive compound and blowing agent are sufficiently stable that the blowing agent will remain in solution for an extended period of time. Nor does this disclosure suggest that foams can be produced from the disclosed “stable” composition by hand mixing.
It has now been found that unexpectedly high levels of a gaseous blowing agent may be incorporated into the B-side of a foam-forming composition at atmospheric pressure if a solubility-enhancing additive is included in the B-side. Blowing agents which may be successfully incorporated into the B-side include: monochloro-difluoro-methane (HCFC-22), 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124), 1,1,2,2-tetrafluoroethane (HFC-134), and 1,1,1,2-tetrafluoroethane (HFC-134a). These incorporated blowing agents do not separate from the other components present in the B-side and may be stored at ambient conditions in closed containers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a storage-stable isocyanate-reactive composition that contains a blowing agent having at least one hydrogen atom and at least one fluorine atom (e.g., an HCFC and/or HFC blowing agent) which is normally a gas at ambient temperature and pressure (i.e., a “low boiling” blowing agent).
It is another object of the present invention to provide a storage-stable polyol/blowing agent composition that may be transported and stored at ambient temperature and pressure.
It is a further object of the present invention to provide a process for the production of rigid foams, especially rigid polyurethane foams, having good physical properties from an isocyanate-reactive composition containing a low boiling blowing agent having at least one hydrogen atom and at least one fluorine atom (hereinafter referred to as “an HFC and/or HCFC blowing agent”) that has been stored at ambient temperature and pressure.
These and other objects which will be apparent to those skilled in the art are accomplished by combining (1) an isocyanate-reactive material such as a polyether polyol or a polyester polyol; (2) an HCFC and/or HFC blowing agent that has a boiling point below the ambient temperature at ambient pressure; and (3) a phenol or alkylphenol, most preferably an ethoxylated alkylphenol in which the alkyl group includes up to 18 carbon atoms. This isocyanate-reactive composition may be stored at ambient temperature and pressure for periods up to as long as 3 months before it is reacted with an isocyanate to produce a foam such as a rigid polyurethane foam.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to storage-stable isocyanate-reactive compositions containing a blowing agent that has at least one hydrogen atom and at least one fluorine atom (i.e., an HCFC and/or HFC blowing agent) having a boiling point below ambient temperature at ambient pressure and to the use of such compositions for the production of foams.
As used herein, the term “storage stable” means that: (1) no more than 5% by weight (based on total weight of the HFC and/or HCFC initially absorbed in or incorporated into the system) of the HCFC and/or HFC blowing agent dissipates from the isocyanate-reactive material(s) over a period of 1 month, preferably for periods as long as 2 months, and in the most preferred cases, for a period of 3 months, when the composition is stored at ambient temperature and pressure (i.e., temperatures of from about 20 to about 25° C. at approximately 1 atmosphere pressure) and (2) the system into which the blowing agent has been incorporated can be used to produce a foam having good physical properties even after such storage.
Any of the isocyanate-reactive materials having a hydroxyl or amino functionality of from about 1 to about 8, preferably from about 2 to about 6.5 and an OH or NH number of from about 25 to about 1850, preferably from about 250 to about 600 known to those skilled in the art may be used in the practice of the present invention.
Suitable organic materials will generally contain two or more isocyanate reactive hydrogen atoms. Examples of suitable isocyanate reactive materials include polyols and polyamines. Polyols are particularly preferred. Examples of appropriate polyols include polyester polyols, polyether polyols, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polyacrylates, polyhydroxy polyester amides and polyhydroxy polythioethers. Polyester polyols, polyether polyols and polyhydroxy polycarbonates are preferred.
Suitable polyester polyols include the reaction products of polyhydric alcohols (preferably dihydric alcohols to which trihydric alcohols may be added) and polybasic (preferably dibasic) carboxylic acids. In addition to these polycarboxylic acids, corresponding carboxylic acid anhydrides or polycarboxylic acid esters of lower alcohols or mixtures thereof may also be used to prepare the polyester polyols useful in the practice of the present invention. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic and they may be substituted, e.g. by halogen atoms, and/or unsaturated. Examples of suitable polycarboxylic acids include: succinic acid; adipic acid; suberic acid; azelaic acid; sebacic acid; phthalic acid; isophthalic acid; trimellitic acid; phthalic acid anhydride; tetrahydrophthalic acid anhydride; hexahydrophthalic acid anhydride; tetrachlorophthalic acid anhydride, endomethylene tetrahydrophthalic acid anhydride; glutaric acid anhydride; maleic acid; maleic acid anhydride; fumaric acid; dimeric and trimeric fatty acids such as oleic acid, which may be mixed with monomeric fatty acids; dimethyl terephthalates and bis-glycol terephthalate. Suitable polyhydric alcohols include: ethylene glycol; 1,2- and 1,3-propylene glycol; 1,3- and 1,4-butylene glycol; 1,6-hexanediol;
Bayer Corporation
Cooney Jr. John M.
Gil Joseph C.
Sloane Carolyn M.
Whalen Lyndanne M.
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