GB476563A - Improvements in the cooking of drying oils and varnishes - Google Patents

Abstract

<PICT:0476563/III/1> For the cooking or polymerization of drying oils and varnishes which contain gums or resin dissolved therein, in closed kettles, a portion of the oil is withdrawn intermittently at frequent intervals, during the cooking and is subjected in a separate vessel while still hot to distillation in vacuo and then returns to the kettle. Undesirable volatile substances such as free fatty or resin acids and hydrocarbons are thereby continuously removed during the process. The whole body of the oil passes through the distillation several times during the polymerization process. Oil is heated at 280--300 DEG C. in a closed aluminium stand oil kettle A provided with stirring gear B and froth breaker C. An upper dome is connected through an overflow pipe D to a vessel E vented to the atmosphere. During heating, carbon dioxide is admitted through a pipe J. A pipe N having a valve P passes from the lower part of the kettle to a distillation chamber R maintained at 1 to 10 mm. of mercury pressure, which is connected through a wide pipe V to a condenser W and vacuum pump Y. Atmospheric pressure in the kettle forces the oil through the pipe N and flows in a thin film over a conical distributer S, and then returns through a pipe T and large capacity pump U to the kettle. Vapours pass to condenser W and collect in a receiver X. The pipe V is provided with an internal gutter Z to collect the reflux which flows into X. Valve P and pump V are so adjusted that the whole oil circulates through R two or three times an hour. The treated oil is finally drawn off through a pipe K and pump L.