Abstract: In a blow molding process in which a parison is blown with a blowing gas containing a reactive gas component capable of reacting with the inner walls of the parison, the blowing gas is removed from the resulting blown article with a purging gas and stored for reuse. The mixture of blowing and purging gases in a reserve tank or other suitable means is adjusted to a certain level of pressure and reactive gas concentration and then recycled as the blowing gas in a subsequent blow molding step. The resulting blown articles from this process have improved properties, e.g. improved impermeability against non-polar solvents when fluorine is the reactive gas.

Abstract: In a blow molding process in which a parison is blown to form an article which is then cooled and recovered, a liquified gas is introduced into the interior of partially blown article where it becomes vaporized and causes the completion of the blowing step as well as to cool the article. A mixture of the blowing gas and vaporized liquified gas is recovered and recycled for use as the blowing gas in a subsequent blow molding step.