Plastics foam prod. for insulation plate structure for buildings

摘要

To produce a plastics foam, using a foaming agent free of fluorochloro hydrocarbons, a coextrusion action forms a foam core (6) and an outer foamed layer. The foam core uses a different foaming agent from the agent for the outer foam layer. The foam core uses a foaming agent with a low vapour pressure, and the outer layer has a physical foaming agent such as CO2, N2 or noble gases. The low vapour pressure foaming agent is a hydrocarbon such as pentane, butane, isobutane and propane.