| 摘要 |
The invention relates to a method for the production of powder-type ethylene vinyl alcohol mixed polymers by radical polymerisation of ethylene and one or several vinyl esters, and optionally other monomers which can be copolymerised therewith, subsequently saponification of the thus obtained ethylene vinyl ester polymer mixture in order to form ethylene vinyl alcohol mixed polymers. The invention is characterised in that the ethylene vinyl alcohol mixed polymer is precipitated, after saponification, from the alcoholic solution by cooling according to a temperature gradient, and optionally, by the addition of water. In ethylene vinyl alcohol mixed polymers which are derived from low molecular ethylene vinyl ester mixed polymers, the average molecular weight Mw varies between 2000 - 100000 g/mol and the temperature gradient is between -0.1 DEG C/min to -10 DEG C/min. In ethylene vinyl alcohol mixed polymers which are derived from high molecular ethylene vinyl ester mixed polymers, the average molecular weight Mw is > 100000 g/mol and the temperature gradient is between -0.1 DEG C/min to -1 DEG C/min. |
