Span S-80 (CAS number: 1338-43-8) has the chemical name sorbitan monooleate, with the molecular formula C24H44O6 and a molecular weight of 428.61. The product appears as an amber to brown viscous liquid at room temperature (melting point 10~12°C) and exhibits excellent water-in-oil (W/O) emulsifying ability. Its molecular structure contains ester bonds and hydroxyl groups, giving the product unique lipophilic characteristics, but also resulting in poor alkali resistance—under strong alkaline conditions, the ester bonds can be hydrolyzed and broken.
This product has an active content of ≥98%, with the main component being monoester (content ≥80%), diester content ≤15%, and free alcohol ≤1.0%. It is difficult to dissolve in water but soluble in various oils and organic solvents, making conventional aqueous pH determination unsuitable for this product. In terms of chemical stability, the product is stable under normal storage conditions but should avoid contact with strong acids, strong bases, and prolonged high-temperature heating. The recommended storage temperature is below 40°C.
As a functional surfactant, the surface activity parameters of Span S-80 are also noteworthy. Its critical micelle concentration (CMC) is approximately 2.5×10−5 mol/L (in water at 25°C), and the surface tension at 1% concentration in liquid paraffin is about 30 mN/m. The product has low foam, weak permeability, and low hygroscopicity. These characteristics make it perform excellently in oil-based systems—it can be used independently as a primary emulsifier or often combined with Tween series (such as Tween-80) to adjust the HLB value, meeting different formulation requirements.
| Parameter Category | Parameter Name | Specification/Value |
|---|---|---|
| Basic Information | Chemical Name | Sorbitan Monooleate |
| CAS Number | 1338-43-8 | |
| Appearance | Amber to brown viscous liquid | |
| Ionic Type | Nonionic | |
| Chemical Characteristic Indicators | Acid Value | ≤10 mg KOH/g |
| Saponification Value | 145~160 mg KOH/g | |
| Hydroxyl Value | 200~240 mg KOH/g | |
| Iodine Value | 65~85 g I₂/100g | |
| Unsaturation | 0.26~0.34 mol/100g | |
| HLB Value | 4.3 | |
| Physical Characteristic Indicators | Density | 0.98~1.05 g/cm³ |
| Kinematic Viscosity (25°C) | 1000~2000 mm²/s | |
| Refractive Index (20°C) | 1.476~1.478 | |
| Melting Point | 10~12°C | |
| Flash Point (Closed Cup) | >150°C | |
| Surface Activity Parameters | Surface Tension | Approx. 30 mN/m (1% in liquid paraffin) |
| CMC | Approx. 2.5×10⁻⁵ mol/L (in water at 25°C) | |
| Quality Indicators | Active Content | ≥98% |
| Moisture | ≤1.5% | |
| Monoester Content | ≥80% | |
| Heavy Metals (as Pb) | ≤10 mg/kg | |
| Arsenic (As) | ≤2 mg/kg |
Span S-80 has an HLB value of only 4.3, making it a typical lipophilic emulsifier, particularly suitable for water-in-oil emulsification systems. In cosmetic creams, sunscreens, and color cosmetic formulations, the recommended dosage is generally 1%~5% of the oil phase weight; in pesticide emulsifiable concentrate formulations, as an emulsifying dispersant, the recommended addition amount is 3%~8%; in the food field (E494), it can be used in bakery fats and non-dairy creamer systems. Due to its low HLB value when used alone, it is often compounded with higher HLB emulsifiers (such as the Tween series) to achieve a wider range of emulsification applicability.