ABSTRACT

HFC-134a is a substitute-blowing agent for HCFC-141b. It has been successfully used in many applications, such as appliance and pour-in-place. However, due to its boiling point and vapor pressure many have discounted HFC-134a acceptability as a blowing agent for spray applied polyurethane foam.

The addition of high levels of HFC-134a to B-side blends results in blends with vapor pressures significantly above atmospheric pressure. This will result in these blends having to be handled in pressurized containers. However, low level of HFC-134a can be added to B-side blends and the vapor pressure can be low enough to handle them in standard containers.

This paper focuses on further developments and improvements achieved in the spray foam systems using gaseous blowing agent (GBAs), which are also relevant to other Polyurethane Rigid (PUR) foam applications. In particular, we demonstrate that Forane® 22/142b is the best choice to produce spray-applied PUR foam products when HCFC-141b is phased out by 2003. However, if this option is unavailable, the paper will also demonstrate that when and where HCFCs are phased out or are no longer available, HFC Forane® 134a the zero ODP can be readily utilized as the most cost-effective substitute to produce spray applied foams with excellent properties.

Nothing contained herein should be taken as an inducement to infringe any patent and the user is advised to take appropriate steps to be assured that any proposed use of these mowing agents will not result in patent infringement. In this regard, among others, the reader should be aware of such basic patents as Bayer’s U.S. 5,496,866 on the use of HFC-245fa as a foam blowing agent, DuPont’s U.S. 5,439,947 & U.S. 5,516,811 on the use of HFC-134a, HCFC-124 and HCFC-22 as foam blowing agents, and non-U.S. counterparts of the forgoing patents.