| 摘要 |
<p>A polyvinyl alcohol purification process is described, which includes heat treating a polyvinyl alcohol under agitation in an atmosphere unsaturated by water and with a water vapour mass content of 20 to 100 %. The process of the invention may also include an additional drying step. A polyvinyl alcohol with an alcohol content, more particularly a methanol content lower than 1 % and an ester content, more particularly a methyl acetate content lower than 1 % is also described, which is provided in the form of flakes a few millimetres in size or of a powder with an average particle size advantageously higher than 600 νm.</p> |
