| 摘要 |
Light-coloured soaps are made by treating an oil containing free fatty acids with a chlorite, then saponifying the chlorite-treated oil with alkali and bleaching the resulting soap with a hypochlorite; the salts used being preferably the sodium salts. If desired, a soapstock may first be mixed with the oil in an amount insufficient to render the mixture neutral or alkaline, the soapstock having previously been bleached by treatment with a chlorite and hypochlorite, according to the method of Specification 762,687. Alternatively, sufficient soapstock to render the mixture neutral or alkaline may be added, the mixture being then treated with chlorite and hypochlorite so that the soapstock is bleached at the same time as the oil in the mixture is being subjected to the chlorite; the treated mixture may then be saponified with alkali and the resulting soap further bleached with hypochlorite. The amount of chlorite used is betwen 0.1-10 per cent, preferably 0.5 per cent, of the oil; the hypochlorate solution (of 14 per cent available chlorine) is used in concentrations between 0.25-20 per cent, preferably 7.5 per cent. The chlorite treatment is suitably carried out at 40-100 DEG C., preferably 80 DEG C., for a period of 5-300 minutes, preferably 30 minutes. If desired the chlorite and/or hypochlorite may be formed in situ by passing chlorine dioxide and/or chlorine gas into the alkaline solution at the appropriate stage in the process. The preferred oils for this process are rapeseed, groundnut, palm, coconut, olive, and palm kernel oils and tallow. Examples and experimental results are given. |
