In developed countries, plastic foams for over 50 years are used as heat insulation products in the form of rigid plates. Long-term thermal engineering parameters of plates made of extruded polystyrene (XPS) were improved with the evolution of blowing agents (BA). Products made of polystyrene foams without Freon (CFC, hcfc, HFC) up until the end of 1950. xps did not churn with the addition of Freon CFC-12 as "eternal", the long-term component that improves thermal performance xps. It was found that the diffusion rate of CFC-12 from the xps boards is very low. At the same time, it became known that the CFC-12 had a devastating impact on the Earth's ozone layer. At the end of 1980. when foaming xps Freon CFC-12 was replaced by HCFC-142b, which is equivalent to the cfc on thermo-technical parameters, but is less harmful to the ozone layer.
It was found that HCFC-142b has a low coefficient of diffusion through a film of polystyrene. As a consequence, plate xps, foam that gas demonstrate the same long-term thermal engineering parameters that insulation, foam CFC-12. Currently, the developing countries of the xps boards produced mainly using HCFC-142b and HCFC-22. The same foaming agents while (until 2010) are used for production of boards and xps in North America. In connection with the prohibition of the use of hcfc refrigerants were developed by various substitutes. One of the best alternatives for long-term thermo-technical parameters in the production of slabs xps was HFC-134a. Group hfc refrigerants do not contain chlorine.