Evaluation of Next Generation Blowing Agents

The majority of the I-IFC evaluations in industry have focused on the more readily available, low boiling candidates such as HFC 134a. Higher boiling HFC candidates that could be handled at ambient conditions and use current processing equipment would be more desirable. This paper will describe results from a research program of two such candidate HFCs performed as a cooperative effort between Martin Marietta Manned Space Systems, the U.S. Environmental Protection Agency, and Oak Ridge National Laboratories. The purpose of this effort was to perform a cursory evaluation of the developmental I-IFCs 245ca and 236ea as blowing agents in urethane based insulations.These two materials were selected from screening tests of 37 C2, C3, and C4 isomers based on physical properties, atmospheric lifetime, flammability, estimated toxicity, difficulty of synthesis, suitability for dual use as a refrigerant, and other factors. Solubility of the two materials in typical foam components was tested, pour foaming trials were performed, and preliminary data were gathered regarding foam insulation performance.

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Evaluation of HFC 245ca and HFC 236ea as Foam Blowing Agents

Sharpe

Macarthur

Liu

et al. 1995

Journal of Cellular Plastics

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Status Report on the Development of a Liquid HFC Blowing Agent

Knopeck

Parker

Richard

et al. 1997

Journal of Cellular Plastics

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CFC blowing agents have been eliminated from virtually all polyurethane foam applications and replaced, in many cases, with the more environmentally acceptable HCFCs. In many applications the preference has been to convert from one liquid blowing agent to another, i.e., from CFC-11 to HCFC-141b. With the planned phaseout of HCFC-141b less than a decade away, there is a clear need for a "next generation" liquid blowing agent to eventually replace HCFC-141b. Previously, we reported the results of preliminary performance evaluations of four promising liquid HFC blowing agent candidates and the screening process used to select those four candidates. In this paper we discuss the environmental, toxicological and performance characteristics of our primary liquid HFC blowing agent candidate. The first criterion for a new blowing agent is environmental acceptability. A candidate must have a zero Ozone Depletion Potential (ODP) and a low Global Warming Potential (GWP), and should be free from other environmental concerns. Accordingly, the paper begins with a discussion of environmental properties such as atmospheric lifetime and GWP. It is equally important that the toxicological properties of a blowing agent candidate be well understood. The results of early toxicity tests have been very promising. These are reported along with a proposed timetable for additional toxicity testing. Ultimately, the acceptability of a new blowing agent will be based on performance. Data from laboratory foam evaluations involving both polyurethane and polyisocyanurate foams are presented. In addition to foam properties, other key performance characteristics such as plastics compatibility, blowing agent stability, foam premix stability and decomposition have been evaluated and are discussed.

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Zero ODP HFC Blowing Agents for Appliance Foam

Doerge

1997

Journal of Cellular Plastics

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Although HCFC-141b has been selected as the best replacement for the blowing agent CFC-11 used in refrigerator or freezer foams in North America, it is only an interim solution in the ongoing efforts to replace CFCs. Under investigation are hydrofluorocarbons (HFCs) which have zero ozone depletion potential (ODP). Papers have been presented at SPI conferences in 1991 and 1993 on one of these compounds, 1,1,1,4,4,4-hexafluorobutane or HFC-356mffm [1,2]. HFC-356mffm, like HCFC-141b, is a liquid with a low boiling point that offers low thermal conductivity in rigid polyurethane foams. It can be processed in existing processing equipment. It is nonflammable and does not form explosive mixtures with air. In addition, it offers good compatibility with appliance plastic food liners. Other potential zero ODP candidates are the isomers of HFC-245. The most promising of these is HFC-245fa. HFC-245fa is a liquid which boils at 150°C (59°F). It is highly miscible with many different polyols. It is reported to be nonflammable and produces foams with low thermal conductivity. Preliminary reports indicate it has shown good compatibility with plastic refrigerator liners, promising toxicity evaluation results, and feasibility of manufacture. The purpose of this paper is to present new information on foam formulations made with HFC-356mffm and one of the isomers of HFC-245. Our studies have shown that HFC-356mffm and HFC-245fa produce low thermal conductivity foams from masterbatches that do not separate upon aging. Information as to the processing of these systems in machinery will be presented. Results of these studies will be compared to a commercial HCFC-141b appliance foam system.

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Evaluation of Next Generation Blowing Agents

Cited by 3 publications

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Evaluation of HFC 245ca and HFC 236ea as Foam Blowing Agents

Evaluation of HFC 245ca and HFC 236ea as Foam Blowing Agents

Status Report on the Development of a Liquid HFC Blowing Agent

Zero ODP HFC Blowing Agents for Appliance Foam

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