Tween-81 (Polyoxyethylene (5) Sorbitan Monooleate) is a high-quality nonionic surfactant produced by Guoli Chemical. At room temperature, it is an amber oily liquid, easily soluble in oils and organic solvents, and can be dispersed in water. Its HLB value of 10.0 is in the middle of the hydrophilic-lipophilic balance, allowing it to be used as an oil-in-water (O/W) emulsifier or, by compounding with lipophilic emulsifiers such as Span series (e.g., Span 80, Span 60), flexibly adjust to a lower HLB value to build a stable water-in-oil (W/O) system. With excellent chemical stability (resistant to acid, alkali, and hard water), good wetting and penetration ability (surface tension about 30-35 mN/m), and broad formulation compatibility, Tween-81 has mature applications in daily chemicals, food, pharmaceuticals, pesticides, and industrial fields.
When using Tween-81, the addition method should be chosen according to the specific process requirements. If used as an emulsifier, first dissolve Tween-81 in the oil phase to be emulsified, then slowly add the water phase under stirring. If necessary, use high-pressure homogenization or a colloid mill to refine the emulsion. If used as a solubilizer, pre-mix Tween-81 with the substance to be solubilized (such as flavors, essential oils, lipophilic active ingredients), then gradually add water and dilute to obtain a clear or bluish opalescent stable system. When compounding with the Span series, the ratio of the two directly affects the final HLB value. The Griffin formula (HLB blend = HLB-A × WA% + HLB-B × WB%) can be used for calculation to match the oil phase emulsification requirements.
| Parameter Item | Value | Description |
|---|---|---|
| HLB Value | 10.0 | Hydrophilic-Lipophilic Balance value, suitable for O/W emulsification and adjusting system HLB through compounding |
| Active Content | ≥97% | High purity ensures stable application effect |
| Cloud Point (1% aqueous solution) | 50-60°C | Reflects the thermal stability boundary of the aqueous system |
| Surface Tension | Approx. 30-35 mN/m | Indicates its ability to reduce interfacial tension; the lower the value, the better the wetting and spreading property |
| Critical Micelle Concentration (CMC) | 0.01-0.1 g/L | Above this concentration, micelles can be effectively formed to exert solubilization and emulsification effects |
| pH Value (1% aqueous solution) | 5.0-7.0 | Nearly neutral acidity and alkalinity, gentle to the formulation system |
| Acid Value | ≤2 mgKOH/g | Low acid value ensures formulation stability |
| Hydroxyl Value | 65~85 mgKOH/g | Can be used for subsequent chemical modification reactions such as esterification |
Based on Guoli Chemical's product database and common industry experience, the recommended dosages of Tween-81 in different applications are as follows (optimal dosage needs to be verified by experiments):
| Application Field | Functional Role | Recommended Dosage (wt%) | Usage Instructions |
|---|---|---|---|
| Cosmetic Creams/Lotions | Emulsifier | 1 ~ 5% | Use in combination with Span 80 or Span 60 to enhance emulsion stability; pre-heat and dissolve in the oil phase before use |
| Makeup Remover Oil/Bath Oil | Solubilizer, Wetting Agent | 3 ~ 12% | Emulsifies upon contact with water, providing a pleasant rinse-off feel; can be used as primary or auxiliary emulsifier |
| Food (Ice Cream, Margarine, etc.) | Emulsion Stabilizer | 0.1 ~ 1% | Must comply with food additive usage standards; recommended to add during the oil melting stage |
| Oral/Topical Pharmaceutical Preparations | Solubilizer, Emulsifier | 0.5 ~ 5% | Used to improve the bioavailability of poorly soluble drugs; dosage should be validated with formulation process |
| Pesticide Emulsifiable Concentrate/Microemulsion | Key Emulsifier | 5 ~ 15% (based on total formulation weight) | Better effect when compounded with anionic emulsifiers (e.g., calcium alkylbenzene sulfonate); ensure uniform dispersion of active ingredients |
| Coatings/Inks | Pigment Wetting and Dispersing Agent | 0.5 ~ 3% (based on pigment weight) | Add during the grinding stage to help reduce viscosity and prevent floating and flooding |
| Metalworking Fluids | Emulsifier, Lubricating Additive | 1 ~ 5% | Use with base oil and |