SOLVENT-FREE CRYSTALLIZATION OF PENTAERYTHRITOL TETRAKIS-Û-3-(3,5-DI-TERT. BUTYL-4-HYDROXYPHENYL)-PROPIONATE¨ AND ITS LAMBDA CRYSTALLINE FORM

摘要

Seeding a melt of pentaerythritol tetrakis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] with a small amount of the crystalline beta -, delta - or lambda -modification of this compound in an extruder, kneader or internal mixer at 70 DEG -130 DEG C. gives, within a few minutes, pure crystalline product without the use of a hitherto mandatory and environmentally undesirable solvent. Also described is a novel crystalline thermostable lambda -modification of pentaerythritol tetrakis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].