. . "A polyvinylpyrrolidone which is particularly suitable for the process according to the invention is prepared by polymerization in an organic solvent, such as isopropanol or toluene, using an organic per-compound, eg. a dialkyl peroxide, as a source of free radicals, with or without a subsequent steam distillation, as described, for example, in German Laid-Open Application DOS 2,515,127." . . .