| 摘要 |
The invention relates to a continuous method for production of polyamide granules, comprising a hydrolytic polymerisation of a mixture of at least one lactam and water to give a low-viscosity polyamide melt at a pressure of at least 5 bar and granulation of the low-viscosity polyamide melt by direct droplet formation with maintenance of a pressure which corresponds to at least the vapour pressure of the water retained in the polyamide melt. The low-viscosity granules thus obtained can be condensed in a single-stage subsequent step by treatment with super-heated steam to give a higher viscosity and unreacted monomers and cyclic oligomers extracted and then dried. The invention is characterised by gentle conditions with reduced residence time and temperatures.
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