Method for improving drying or semi-drying oils

摘要

Drying or semi-drying oils are isomerized by heating them for a time not exceeding 40 minutes at a temperature of 160 DEG C. to 220 DEG C. in the presence of a nickel catalyst containing a proportion of sulphur not exceeding 10 per cent based on the weight of the nickel. The temperature is such that the conjugation of the double bonds is a maximum and the bodying is a minimum. The drying oil specified is linseed oil. The mixture is kept at the desired temperature for not less than 5 minutes and preferably between 10 and 30 minutes. The temperature is preferably 180 DEG C. The catalyst may be prepared as described in Specifications 645,872 and 646,919. The amount of catalyst used may be 4 to 10 per cent by weight of nickel based on the oil to be isomerized. The heating is preferably continuous and the mixture agitated. The mixture may be passed downwards through a coil consisting of a heating zone, a reaction zone, and a cooling zone.