Span S-40 (Span 40) is a classic nonionic surfactant, chemically known as sorbitan monopalmitate, appearing as a light yellow waxy solid. Its molecular structure combines hydrophilic sorbitan groups with hydrophobic palmitic acid long chains, giving it excellent water-in-oil (W/O) emulsifying capacity. Additionally, this product is resistant to acids, alkalis, and hard water, exhibiting stable performance in complex formulation systems. It has broad compatibility with various ionic and nonionic auxiliaries, making it an indispensable functional additive in many industrial formulations.
In terms of process applications, Span S-40 plays multiple functional roles: in the preparation of emulsions and creams, it can be compounded with Tween series products to precisely adjust the HLB value, building a stable and fine emulsification system; in pigment dispersion processes, it effectively adsorbs onto pigment particle surfaces, shortening grinding time and preventing flocculation and re-agglomeration; in plastic processing, as an internal additive, it can migrate to the product surface, continuously exerting antistatic and anti-fogging effects.
| Industry Field | Functional Role | Typical Process and Application Scenarios |
|---|---|---|
| Cosmetics and Personal Care | W/O Emulsifier | Used in the emulsification preparation process of creams, lotions, and sunscreens to form a W/O emulsion system with a fine skin feel and good stability |
| Food Industry | Emulsifier, Stabilizer, Defoamer | Applied in the homogenization and stabilization processes of baking oils, whipped cream, protein beverages, etc.; complies with FDA 21 CFR 172.842 standards |
| Pharmaceutical Preparations | Pharmaceutical Excipient, Emulsion Base | Used in the emulsification and dispersion process of creams, suppositories, and other preparations to improve drug dispersion uniformity and bioavailability |
| Pesticide and Environmental Formulations | Emulsifier, Dispersant | Used in the processing of emulsifiable concentrates (EC), emulsions in water (EW), suspension concentrates (SC), etc., to enhance the wetting and spreading performance of the liquid on plant surfaces |
| Textile Industry | Softener, Antistatic Agent | Added to spin finish formulations to impart smoothness, bundling, and antistatic properties to fibers during fiber drawing and finishing processes |
| Plastics Industry | Internal Antistatic Agent, Anti-fogging Agent | Internally added during plastic film blow molding or injection molding processes; after migration to the surface, it eliminates static charge buildup and prevents water droplet condensation that affects light transmittance |
| Coatings and Inks | Pigment Dispersant | Used in grinding and dispersion processes to significantly shorten grinding time, prevent pigment particle flocculation and re-agglomeration, and improve color strength and storage stability |
The HLB value of Span S-40 is approximately 6.7. When used alone, it is suitable for preparing W/O emulsions. For preparing O/W emulsions, it is recommended to compound it with high-HLB Tween series products (such as Tween-60, Tween-80), adjusting the ratio to achieve the target HLB value. The recommended dosage in cosmetic formulations is typically 1% to 5%, while in pesticide formulations, the dosage depends on the specific formulation type, generally 2% to 8%.
Before use, it is recommended to heat Span S-40 to 50 to 60°C to melt it, then mix it uniformly with the oil phase components to fully exert its emulsifying and dispersing efficiency. In plastic film anti-fogging applications, the recommended addition amount is 0.5% to 1.5% (relative to the resin weight), and compounding with Tween-type additives yields better results.