Coal tar extract with a reduced content of hydrocarbons and dermatological and cosmetic compositions containing the same

Abstract

The invention concerns a coal tar extract with reduced polycyclic aromatic hydrocarbon content and a method for obtaining same using two sequentially linked distillation systems. The invention also concerns cosmetic and dermatological preparations containing said resulting coal tar extract.

1 . Coal tar extract, characterized in that its maximum content of polycyclic aromatic hydrocarbons is about ten parts per million (ppm) and its maximum content of benzo(a)pyrene is about a few ppm.  
     
     
         2 . Coal tar extract according to    claim 1   , characterized in that its content of polycyclic aromatic hydrocarbons is less than about 4 ppm and its content of benzo(a)pyrene is less than about 1 ppm.  
     
     
         3 . Process for obtaining a coal tar extract according to    claim 1    or    2   , from crude coal tar, characterized in that it uses at least two distillation systems connected in series.  
     
     
         4 . Process according to    claim 3   , characterized in that the first system is a thin-film evaporator and/or the second system is a distillation column.  
     
     
         5 . Process according to    claim 4   , characterized in that the distillation on a thin-film evaporator is carried out under a pressure of 5 to 7 mmHg, between 198° C. and 200° C., and at a crude coal tar feed rate equal to 18 to 19 kg/h.  
     
     
         6 . Process according to    claim 5   , characterized in that the distillation on a distillation column following distillation on a thin-film evaporator is carried out at from 260° C. to 320° C.  
     
     
         7 . Cosmetic or dermatological compositions containing a coal tar extract according to    claim 1    or    2    or obtained by the process according to one of    claims 3    to    6   .  
     
     
         8 . Cosmetic or dermatological compositions according to    claim 7   , characterized in that they contain 0.1 to 10% by weight of coal tar extract.