Patent ID: 7001549

Claim:
A process for the production of physically foamed injection molded articles, wherein in a first stage a propellant-free first melt portion is fed into a cavity (initial filling), in a second stage adding a quantity of a physical propellant at elevated pressure to a second melt portion (propellant injection phase) and injecting the second melt portion containing the quantity of propellant into the cavity and optionally in a third stage a propellant-free third melt portion is charged into the cavity, the production of the injection molded articles occurring in the cavity; wherein metering of the quantity of the physical propellant in the second stage occurs in a pressure regulated manner, wherein the pressure which is exerted on the propellant during the propellant injection phase is greater than the pressure which is exerted on the propellant in the phases between or before or after metered addition, and the expansion of the quantity of the propellant added to the melt occurs in the cavity including maintaining the propellant under pressure an intermediate cycle time before and after the propellant injection phase; maintaining the propellant at a pressure of at least p (crit) at a given temperature during the intermediate cycle time.