Tween T-81 (Polyoxyethylene (5) sorbitan monooleate, CAS: 9005-65-6) is a high-quality nonionic surfactant produced by Guoli Chemical, with an effective content ≥97%, appearing as a light yellow to amber oily liquid, slightly hygroscopic. Its HLB value is 10, making it a lipophilic oil-in-water (O/W) emulsifier with additional functions of solubilization, wetting, and dispersion. This product is readily soluble in oils and organic solvents and disperses in water. This solubility characteristic determines the core point of its usage: first dissolve in the oil phase, then mix with the water phase.
In actual operation, the usage of Tween T-81 varies depending on the application scenario. When used as an emulsifier, it is usually added to the oil phase according to the formula amount, stirred evenly and heated appropriately (recommended 40~60°C) until completely dissolved, then slowly add the oil phase to the water phase under continuous stirring, or vice versa. Emulsions with finer texture can be obtained by using a homogenizer or high-shear equipment. If used as a solubilizer, directly mix Tween T-81 with the substance to be solubilized (such as essential oils, fragrances, or poorly soluble drugs), stir evenly, then slowly add water to dilute to a transparent or translucent state.
The excellence of Tween T-81 lies in its synergistic combination capability with the Span series (such as Span S-80). By adjusting the ratio of the two, the emulsification system can be precisely customized within a wide HLB range of 1.8 to 10, meeting the needs of different emulsion types from W/O to O/W. In actual formula development, it is recommended to first determine the optimal dosage and combination ratio through experiments to obtain the most stable emulsification effect.
| Parameter Item | Value (Measured by Guoli Chemical) |
|---|---|
| Effective Content | ≥97% |
| HLB Value | 10 |
| Appearance | Light yellow to amber oily liquid |
| Solubility | Readily soluble in oils and organic solvents, disperses in water |
| Density (20°C) | 1.00~1.05 g/cm³ |
| Cloud Point (1% Aqueous Solution) | 50~60°C |
| pH Value (1% Aqueous Solution) | 5.0~7.0 |
| Kinematic Viscosity (25°C) | 200~500 mm²/s |
| Flash Point | ＞150°C |
| Foam Characteristics | Low Foam |
Cosmetic creams/emulsions: Add Tween T-81 (recommended dosage 0.5%~3%) to the oil phase, heat to 50~60°C until fully dissolved, preheat the water phase to the same temperature, mix the two phases and homogenize for 3~5 minutes. For a more stable W/O system, it can be used in combination with Span S-80 (HLB value 4.3).
Pesticide emulsifiable concentrates/microemulsions: Recommended dosage 3%~8%. First mix the active ingredient with the solvent evenly, add Tween T-81 and stir thoroughly until transparent. Dilute with water before use, and it will self-emulsify to form a stable emulsion.
Metalworking fluids: In cutting fluid formulations, Tween T-81 (dosage 2%~5%) can be used as an emulsion stabilizer and anti-rust auxiliary. It is recommended to combine it with anionic emulsifiers such as sodium petroleum sulfonate to enhance emulsion stability and extreme pressure lubrication performance.
Coatings and inks: As a pigment wetting and dispersing agent, add 1%~5% of the pigment mass. First mix with the resin solution, then add the pigment for grinding and dispersion, effectively preventing floating and flooding.