1. Field of the Invention
This invention relates to cellular polyurethanes and polyisocyanurates and to intermediates therefor, especially novel fluorocarbon compatibilized, homogeneous polyol blends, resin precursor blends incorporating such polyol blends, and their usage in processes for making such cellular products.
2. Description of the Prior Art
Cellular polyurethanes and polyisocyanurates are well known in the art for use in thermal insulating applications. Minor amounts of certain polyols are commonly added to the foam forming composition to modify foam properties. When a fluorocarbon blowing agent is employed, a problem in compatibility between the polyol (especially aromatic polyester polyols) and such fluorocarbon may arise in resin precursor blends.
As those skilled in the art appreciate, the preparation of polyol blends and resin precursor blends (which typically commercially comprise such polyol blends, blowing agent, cell stabilizing surfactant, and trimerization catalyst) in the isocyanate polymerization art can involve multi-component mixtures. While sometimes a blend of different polyols present in a resin precursor blend can overcome fluorocarbon compatibility problems, characteristically when aromatic polyester polyols are used, such compatibility problems are believed to be difficult to overcome without using a compatibility agent. Aromatic polyester polyols are desirable for use in such blends because they have a relatively low cost yet can produce product foams of good physical characteristics.
Aromatic polyester polyols, however, apparently cannot be blended directly with usable amounts of fluorocarbon blowing agents because of mutual insolubility characteristics. Compatibility agents can be employed in polyol blends and resin precursor blends to produce miscibility between the fluorocarbons and the polyols. However, compatibility agents, especially when employed at the relatively high levels needed to achieve a desired level of compatibilization, can adversely interfere with the characteristics desired in a foam produced from a blend incorporating such.
A class of amide diols is disclosed in U.S. Pat. No. 4,246,364 as being useful compatibility agents for such polyols and fluorocarbon blowing agents when material of such class is employed at the relatively high rate of from about 20 to 70 weight percent apparently on a 100 weight percent total polyol weight basis. Certain types of poly diols, such as aromatic ester diols produced from reacting aromatic esters with low molecular weight aliphatic polyols, appear to be so incompatible with fluorocarbon blowing agents that, in a polyol blend containing such aromatic polyester polyols in relatively high percentages, large amounts of such an amide diol appear to be needed to achieve compatibility with fluorocarbon blowing agents. When such a large quantity of amide diol is employed, the cost of foam manufacture increases (because of the cost of the amide diol).
One class of aromatic polyester polyols which has heretofore been successfully employed in this art, and which is relatively incompatible with fluorocarbon blowing agents, but which is compatibilizable therewith by using an amide diol of the above referenced Koehler et al '364 U.S. Patent, comprises polyester polyol reaction products of a low molecular weight polyether polyol, such as diethylene glycol, with poly(carbomethoxy-substituted) diphenyls and/or benzyl esters. Such product polyols are available commercially under the trademark "Terate" from ICI Americas, Inc. and "Urol" from UCT, Inc. Such diethylene glycol diphenyl and benzyl esters are typically commercially used at rates apparently ranging up to about 70 to 90 weight percent of a total polyol blend in making polyisocyanurate foam products. As a class, such "Terate" type polyol compositions are characteristically primarily based on diphenyl esters, while another type of such aromatic ester polyol, the phthalate polyester polyols, are primarily based essentially on single aromatic substituted monophenyl ring structures.
Certain monofunctional hydroxyl terminated nonionic surfactants, such as, for example, polyethoxylated alkyl phenol nonionics that contain not more than about 15 moles of condensed ethylene oxide per molecule, and thus have molecular weights substantially below about 900, are believed to have been heretofore used as compatibility agents for polyol/fluorocarbon blowing agent resin precursor systems (see Hughes, J. M. & Clinton, J. L. "Development Of Lower Cost Polyurethane Modified Polyisocyanurate And Polyurethane Rigid Foams" paper given at (SPI 25th Annual Urethane Technical Conference 10/29/79). These prior art nonionic compatibility agents contain substantially no propylene oxide. Particularly when formulating blends of phthalate ester polyols with fluorocarbon blowing agents, it appears to be necessary, in order to achieve the desired blend homogeneity, to use significantly high concentrations of such prior art nonionic surfactants for specified respective amounts of specified aromatic polyester polyols and fluorocarbon blowing agents which is undesirable not only from a cost standpoint, but also from a standpoint of degrading product foam properties, such as compressive strength. The foam property degradation can be so great as to make the product foams unusable and unsuitable for many conventional commercial foam applications. This property deterioration is attributed in theory (and there is no intent to be bound herein by theory) to the circumstance that the monohydroxyl funtionality of such surfactants makes them react as chain terminating components in the polyurethane and/or polyisocyanurate polymerization reaction, thereby producing excessive amounts of low molecular weight urethane and/or isocyanurate polymer which may result in such losses in desirable product properties.
Previously, I discovered that a mixture of, for example, an amide diol of the above referenced Koehler et al '364 U.S. Patent with a certain type of block ethoxylate propoxylate compound was useful even at relatively high concentration levels for comptabilizing fluorocarbon blowing agents with aromatic polyester polyols; see my aforereferenced application U.S. Ser. No. 622,670. The present application relates to my further discovery that certain ethoxylate propoxylate compounds are usable is desired by themselves at relatively low concentration levels as compatibility agents for such aromatic polyester polyols.
There remains a need in the art for new and improved compatibility agents which will permit one to compatibilize polyols, especially aromatic polyester polyols, with fluorocarbon blowing agents and thereby achieve complete blend homogeneity and solubilization without causing any substantial deterioration in product foam properties.