Castor oil polyoxyethylene ether EL-90 (PEG-90 castor oil) is typically used as a primary emulsifier or solubilizer in oil-in-water (O/W) systems due to its high HLB value of 16-17 and excellent hydrophilicity. Its melting point is 35~40°C, and it appears as a light yellow to yellow paste or viscous liquid at room temperature. Therefore, before charging, it is recommended to preheat it to a flowable state using indirect heating methods (such as a water bath or warm room) to facilitate accurate metering and rapid dispersion. Direct heating with an open flame is strictly prohibited.
In actual formulation operations, the specific usage method of EL-90 varies depending on the application scenario. When used as an industrial or pesticide emulsifier, it is usually first mixed uniformly with the oil phase components, and then the water phase is slowly added under stirring, or it directly participates in the oil-water two-phase mixed emulsification. In daily chemical products (such as creams, lotions), it often serves as a mild emulsifying and solubilizing component, and can be compounded with other emulsifiers (such as glyceryl monostearate, fatty alcohol polyoxyethylene ether) to adjust the HLB value and emulsification effect. In metalworking fluid formulations, it is used to emulsify base oils and extreme pressure additives, while also providing synergistic lubrication and rust prevention. It is generally recommended to use in neutral or slightly alkaline (pH 5.5~7.5) systems to ensure its chemical stability.
Based on official data from Guoli Chemical, the critical micelle concentration (CMC) of EL-90 is extremely low, only 0.01~0.02 g/L, meaning it can effectively reduce surface tension and form micelles at very low concentrations. Therefore, in cleaning and solubilization applications, its usage concentration is usually much lower than that of other traditional surfactants. The specific dosage needs to be determined through experiments, but in most emulsion polymerization or emulsification applications, the recommended dosage is typically 2%-6% of the total formulation; in high-concentration concentrated emulsions or certain pesticide emulsifier formulations, its proportion may be higher. Because this product has excellent resistance to acids, alkalis, hard water, and electrolytes, it can be widely used in various complex industrial formulations.
| Parameter Item | Typical Value | Impact on Usage Method |
|---|---|---|
| Appearance | Light yellow to yellow paste/viscous liquid | Recommend warming (>35°C) before use for accurate metering and uniform dispersion |
| HLB Value | 16-17 | Suitable for oil-in-water (O/W) systems as a primary emulsifier or efficient solubilizer |
| Cloud Point (1% aqueous solution) | 91.0~96.0°C | Maintains good surface activity in high-temperature processes (e.g., some metalworking, textile pretreatment) |
| Critical Micelle Concentration (CMC) | 0.01~0.02 g/L | Extremely high surface activity, enabling emulsification and solubilization at very low concentrations |
| Solubility | Readily soluble in water, ethanol, acetone, etc. | Can be directly dissolved in water phase or oil-water mixed phase, flexible usage process |
| Chemical Stability | Resistant to acids, alkalis, hard water, and oxidants | Can be safely used in formulations with a wide pH range and complex ingredients containing electrolytes |