Low Permeability Polyols for Rigid Foam Applications

Abstract

The decreased emphasis on the use of CFC blowing agents for rigid foam has placed a greater demand on the performance of the polymer in the foam. One area where higher performance is needed is in permeability. In order for non-CFC foam to retain its insulation performance the permeation of low k-factor blowing agent out of the foam and the permeation of high k-factor air into the foam must be minimized. This paper will present data on several new types of polyols which have been designed specifically to give lower permeability than conventional rigid foam polyols. Data on the permeability of both air and carbon dioxide for these polyols was developed on both compression molded thermoset polymer films and foam samples. These polyols gave significant improvement in both carbondioxide retention and air exclusion which lead to improved k-factor aging in the foam samples.

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

“…The dotted lines present linear regression of permeability vs 1/ M c . The P CO 2 estimates obtained at the greater crosslink densities, Figure c, are commensurate with the higher values of the permeability range of 5.4 × 10 –14 to 6.7 × 10 –13 m 2 /s reported in refs , and for rigid PU. The air permeability values, Figure b, are also near the literature data range of P air = 8.6 × 10 –15 to 1.6 × 10 –14 m 2 /s at the higher crosslink densities.…”