| 摘要 |
A multi-step blow molding process for producing fuel containers having excellent resistance to permeation by hydrocarbon fuels and organic fuel additives such as lower alkanols and ethers. In blow molding, a parison is formed from a thermoplastic material, expanded within a closed mold by means of an inflating gas for conforming the parison to the shape of the mold and fluorinated under conditions sufficient to effect surface fluorination of the interior of the parison. The parison is evacuated and the article recovered. The improvement in the blow molding operation comprises pressurizing the parison with a reactive fluorine containing gas containing from 0.1 to 1% fluorine by volume while the parison is at a temperature above its self supporting temperature and for a time sufficient to effect fluorination of the interior surface of the parison. Subsequently, the interior surface of the pre-fluorinated parison is pressurized with a reactive fluorine containing gas containing at least twice the initial concentration but not less than about 1% fluorine by volume for a time, typically from about 2 to 30 seconds to form said fluorinated parison having reduced permeability.
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