ABSTRACT
Nothing herein should be construed as an inducement to infringe any patent including, but not limited to, U.S. Patent No. 5,906,999, U.S. Patent No. 6,218,443, and U.S. Patent No. 6,010,649.
Hydrochlorofluorocarbons have been banned in the US from use in integral skin foam applications for over five years. During this period, CO2 (water) and HFC-134a have been used with varying degrees of success in these formulations. However, compared to CFC-11, foams blown with water and HFC-134a are both characterized by poor skin formation.
Since the phase-out of HCFCs in integral skin foam in January 1, 1994, Honeywell has done considerable work to develop a next generation blowing agent and is now commercializing HFC-245fa (1,1,1,3,3-pentafluoropropane) to replace HCFCs. A world-scale HFC-245fa plant is now being built by Honeywell in Geismar, Louisiana. The plant is on schedule to be commercially operational by mid-2002. HFC-245fa is well known as a third generation blowing agent with zero ozone depleting potential (ODP), non-flammability, and acceptable global warming potential (GWP). With the commercialization of HFC-245fa, applications like integral skin foam that need a better performing blowing agent may find a solution to problem areas that have not been met by water and HFC-134a.
In this paper, a CFC-11 based integral skin foam formulation was used to compare the physical properties of foams prepared using CFC-11 or HFC-245fa, especially skin thickness. A blowing efficiency study was conducted. For each blowing agent, two 16pcf and 32pcf foams were molded with free rise densities of 8pcf and 16pcf and pack factor of 2. The relationship of integral skin foam properties with regard to variables such as mold temperature and packing level was also explored. The results showed that at the same weight percent loading of blowing agent in the formulation, the free rise density of HFC-245fa blown foams was approximately one-half that of the CFC-11 blown foams. This indicates that HFC-245fa has much higher blowing efficiency than CFC-11 even though the two have very similar molecular weight. This result is consistent with our previous work. The results also showed that HFC-245fa gave similar skin thickness compared to CFC-11 and showed very similar change in skin thickness as mold temperatures or packing levels were varied.
As a more cost-effective albeit lower performance option, HFC-245fa/CO2(water) blends were also studied in this work. Two water levels, 10mol% and 30mol%, were formulated to make foam with same free rise density as neat HFC-245fa. The results showed that addition of water lowered the vapor pressure of the polyol premix. The results also indicated that water caused higher in-mold pressure. Even at 30mol% water level, a good skin quality was obtained.
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