As environmental pressure increases worldwide, it is becoming necessary for foamers to eliminate chlorinated products - such as chloro fluoro carbons (CFCs), methylene chloride, 1.1.1 trichloroethane - or any type of volatile organic compounds (VOC's) from their production. In some countries these additives have already been banned: the impact on the flexible foam industries would be to increase foam prices and to eliminate certain soft grades.

The use of liquid carbon dioxide (CO₂) as an expanding agent in a polyurethane foam is a good and well accepted idea. Handling this liquid, which gasses off at room temperature, has always been one of the main problems. Its use - although the subject of various patents - has been scarcely put into current practice, mostly because of inherent problems linked with the formation of typical “chimneys” in the foam, i.e. long, narrow cavities oriented in the rise sense, generated by the uncontrolled expansion of carbon dioxide.

Possible solutions to this problem can be found by investigating several aspects of the process: chemicals selection, CO₂ dispersion into the formulation, gas nucleation, metering equipment, mixing chamber's geometry, foam's lay-down, rise profile, but until now no suitable method was available and this interesting opportunity was left aside.

Cannon started investigating this matter after having spent several years in the development of a suitable pre-mixing device for LBBA's (Low Boiling Point Blowing Agents). The original program started in 1989 when liquid carbon dioxide was tried for the expansion of low-density rigid foams for insulation applications (refrigerators, panels etc). Heavy frothing effect was noticed when loading high amounts of CO₂ in conventional polyols. Cell structure was acceptable, but frequent “chimneys” were still present. On top of that, the lambda value of a CO₂-blown foam was still not attractive for most of the applications.

The project was temporarily put on hold, giving priority to other more promising alternative blowing agents (HCFC 22, 142b, HFC 134a, etc) because of their higher insulation capacity and better solubility in conventional polyols.

Now (after having successfully solved the problem of metering and mixing gaseous blowing agents with the EasyFroth™ unit and cyclopentane with the Multi EasyFroth™ version) Cannon have developed and patented a proprietary method for the addition of liquid CO₂ to flexible foam formulations for slabstock. This revolutionary new process - for which a patent is pending - is named CarDio™ from carbon dioxide: it enables foamers to continue producing their existing foam grades at a lower chemical cost, due to the significant price differential between CFC's, ABA's and CO₂. Its peculiar foaming method can also - if one likes - dramatically reduce the size of the foaming plants, thereby deriving the advantages of reduced floor space and plant volume.