Span, also known as sorbitol fatty acid ester. This product is white or yellowish waxy, flaky and powdery (≥100 mesh). Soluble in hot ethanol, ethyl ether, methanol and carbon tetrachloride, slightly soluble in ethyl ether, petroleum ether, can be dispersed in hot water, is a W/O emulsifier, has a strong emulsification, dispersion, lubrication.
Drug alias: Anhydrous sorbitol fatty acid ester
English name: Span
Molecular formula: C7H11O6-R Molecular weight: 346.45~957.46
Properties: It can be mixed with various kinds of surfactants, especially suitable for Tween-60 (T-60), with better effect. HLB(hydrophilic and oil-wet equilibrium) value is 4.7, melting point is 52-57℃.
Function: it is the ester formed by sorbitol and different higher fatty acids, such as sp-20 (SP-20) is laurate ester; Sp-80 (SP-80) is monooleate. It's emulsifying.
Usage and dosage: used for preparing oil-in-water emulsion.
The original process of Stepan -80 adopts vacuum esterification, during the reaction, the water generated in the reaction is continuously removed, in order to facilitate the reaction in the direction of balance. However, due to the high reaction temperature and the low partial pressure of water vapor in the reaction system (less than 40mmHg), the side reaction is extremely difficult to control, so the product quality is extremely unstable, the viscosity changes greatly, and the emulsifying performance is poor.