0 460 450), optionally also with addition of an entraining agent, such as nitrogen or carbon dioxide, or with the use of a vacuum (cf. for example EP-A 0 039 96, EP-A 0 256 003, U.S. Pat. No. 4,423,207), alternatively also by subsequent crystallization (cf. for example DE-A 34 29 960) and/or expulsion of the residues of the solvent by heating in the solid phase (cf. for example U.S. Pat. No. 3,986