Class I Isocyanurate Foams Blown with Pentane

The transition from CFCs to HCFCs and zero ODP compounds, as mandated by CFC phase out protocol, is well under way in most areas of urethane foam production. Specifically, the laminate board industry is in the process of converting to HCFC-141b as an intermediate solution to R-11 blown foams. The switch will serve the industry for the next few years. However, HCFCs also destroyozone, and 141b is perhaps the strongest ozone depleter among HCFCs in current use. Consequently, 141b must eventually be replaced with a zero ODP alternative. Recently announced EPA recommendations call for cessation of both production and consumption of 141b by the year 2003 [1].

Therefore, current research is concentrated on developing effective, economical, zero ODP options for laminate board production. The task is large, however, due to the many requirements imposed on the product. Good k-factors and flame resistance are important. In the past, these requirements were met through both the isocyanurate structure of the foam and the low flammability and thermal conductivity of the blowing gas.

BASF is currently investigating the use of hydrocarbons such as pentane as blowing agents for laminate board. Hydrocarbons are inexpensive, abundant liquids which have a zero ODP (ozone depletion potential) and a low GWP(global warming potential). We have produced laminate board foams with reasonable k-factors (0.135-0.146) and surprisingly good flame resistance using n-pentane, cyclopentane, and 2-chloropropane [2]. The good k-factors and improved flame resistance have been achieved through the use of such tools asincreased index, use of phosphorous-containing polyols, and the addition of halogenated inerting agents. Our results to date indicate that with a proper combination of these techniques, potential Class I rated laminate board blown with hydrocarbons is possible.