Preparation Process and Performance of Sodium Lauroyl Methyl Isethionate

Sodium lauroyl methyl isethionate (SLMI), the improved product of sodium cocoyl isethionate, is a new type of anion surfactant, belong to fatty acid ester of sodium isethionate. The main raw material of the product comes from the nature, so the product is a green anionic surface active agent.Due to good surface activation, good foaming ability, and excellent ability of anti-hard water, this product is widely used in personal cleansing products, such as shampoo, face cream, beauty soap and so on. There are few reports and papers about the method and experimental condition of the synthesis of sodium lauroyl methyl isethionate. In this paper, we explore the process of synthesis of sodium lauroyl methyl isethionate to find the best synthesis method, the optimal synthesized conditions were studied also, and some products were characterized and tested.Based on the process of synthesis of sodium cocoyl isethionate, we design experiments with different conditions, to compare the colour and the active matter content of the product in such experimental conditions, and find the process of synthesis of sodium lauroyl methyl isethionate. The synthetic method is:Using lauric acid and sodium methyl isethionate as the raw materials, the sodium lauroyl methyl isethionate was prepared catalyzed by catalyst without the existence of solvent and water-carrying agent; by comparing several commonly used catalysts, such as SO42-Fe2O3、SO42-/SnO2、W-Mg-Sn composite catalyst、ZnO、ZnCl2、 p-toluenesulfonic acid and oil of vitriol, the results show that p-toluenesulfonic acid has the highest catalytic activity.This paper takes the percent conversion of reaction and the content of active matter in the product as evaluation criterion, to find the optimal process conditions by single factor experiment for5main factors. The results show that in the conditions:reaction temperature:160℃, matching of lauric acid and sodium methyl isethionate(mol:mol):1.6:1, the amount of catalyst:1.0%, vacuum capactive of the system:lOkPa, reaction time:6h, the percent conversion of reaction can be94.41%and the content of active substance in the product can be77.62%.In addition, this paper takes performance evaluation of the product. Experimental results show that the surface tension of the product is27.52mN/m, and the critical micelle concentration is1.8×10-3mol/L, the foam force of the product is226mm at ambient temperature, the HLB is10to13, it has good solubility in water and has excellent resistance to hard water capacity.