Span S-40 (HLB value approx. 6.7, melting point 45-47°C) is a waxy solid at room temperature, insoluble in water but soluble in hot oils, fatty acid esters, and various organic solvents. Before use, it is recommended to heat it to 50-60°C to completely melt it into a clear liquid, then add it according to the formulation amount into the oil phase components and stir well. For preparing W/O emulsions, the classic "hot emulsification method" is most reliable: heat the oil phase (containing Span S-40) and the water phase separately to the same temperature (usually 5-10°C above the melting point), then slowly pour or drip the water phase into the oil phase under high-speed homogenization or stirring to form a stable water-in-oil emulsion.
In dispersing and wetting applications (such as paint color pastes, pesticide suspensions), the molten Span S-40 can be pre-mixed with solvents or liquid carriers, and then solid pigments or active ingredient particles are introduced, utilizing its excellent wetting capability to help powder deaerate and disperse quickly. When used as an internal anti-fog/antistatic additive in plastic films, Span S-40 should be premixed or melt-blended with resin masterbatch, and its migration characteristics allow it to gradually migrate to the film surface after film formation.
Span S-40 has excellent compatibility. In most formulations, it can be combined with Tween series (e.g., Tween-40, HLB 15.6) to obtain a wider HLB value range, thereby flexibly adjusting the stability and feel of the emulsifying system. It is recommended to optimize the ratio using algebraic methods or phase diagrams based on the "required HLB value" of the oil to be emulsified.
| Parameter Item | Typical Value | Description |
|---|---|---|
| Appearance | White to light yellow waxy solid | — |
| HLB value | 6.7 | Suitable for W/O emulsions |
| Melting point | 45-47°C | Recommended to heat to 50-60°C for melting before use |
| Acid value | ≤8 mgKOH/g | — |
| Saponification value | 140-150 mgKOH/g | — |
| Hydroxyl value | 255-290 mgKOH/g | — |
| Water content | ≤1.5% | — |
| Flash point | >200℃ | — |
| Solubility | Insoluble in water, soluble in hot oils and organic solvents | — |
| Packaging | 25kg/woven bag or kraft paper bag | — |
| Application Field | Typical Dosage (mass %) | Process Suggestions |
|---|---|---|
| Cosmetic creams/lotions | 1.0% - 5.0% | Co-heat with oil phase to 70-75°C, homogenize emulsify |
| Food emulsification (whipped cream, baking fats) | 0.2% - 1.0% | Add according to GB 2760 regulations, dissolve in oil before use |
| Pharmaceutical creams/suppository bases | 1.0% - 10.0% | As W/O emulsifying base, melt and mix with active ingredients |
| Pesticide emulsifiable concentrates/emulsions in water | 2.0% - 8.0% | Combine with anionic emulsifiers to enhance stability and spreadability |
| Paint/ink pigment dispersion | 0.5% - 3.0% of pigment weight | Add before grinding to aid pigment wetting and viscosity reduction |
| Textile spinning oil agents | 3.0% - 10.0% | Formulate with mineral oils, synthetic esters, and other emulsifiers |
| Plastic antistatic/anti-fog masterbatch | 1.0% - 3.0% (in film) | Melt blend with resin carrier for granulation, then add for film blowing |