It is recommended to incorporate Polyoxyethylene Stearate SG-40 using the "warm water pre-dispersion" or "oil phase hot melt" method, with a recommended dosage of 1% to 5% of the total system weight, precisely adjusted according to the specific application scenario.
Detailed Description
Polyoxyethylene Stearate SG-40 (PEG-40 Stearate) is a white to light yellow waxy solid at room temperature, with a high HLB value of 16-17, making it an extremely hydrophilic O/W type nonionic emulsifier. The key to its usage lies in ensuring its complete dissolution or uniform dispersion into the formulation system to achieve maximum efficacy. Since the product has a melting point of approximately 48-52°C, adding it directly to an ambient temperature system can lead to slow dissolution or clumping, thus pretreatment is typically required.
In various industrial formulations, SG-40 can be used as the primary emulsifier alone, or compounded with low HLB value emulsifiers (such as Polyoxyethylene Stearate SG-6, HLB≈10) to synergistically achieve a wider emulsification range and finer emulsion stability. It maintains outstanding chemical stability in acid, alkali, and electrolyte solutions, making its addition sequence relatively flexible; it can be added either during the oil phase stage or after the water phase has been heated.
Technical Parameters
| Parameter Index | Typical Value (Guoli Chemical Data) | Application Reference Significance |
|---|
| Appearance | White to light yellow waxy solid | Requires melting or pre-dispersion before use |
| HLB Value | 16-17 | Highly hydrophilic, suitable for O/W systems, often compounded with low HLB emulsifiers |
| Melting Point | 48-52°C | Recommended to preheat to 50-60°C for melting |
| Cloud Point (1% aq. solution) | >100°C | Stable in high-temperature systems, not prone to precipitation |
| pH (1% aq. solution) | 5.0-7.0 | Nearly neutral, minimal impact on formulation acidity/alkalinity |
| Surface Tension (1%, 25°C) | Approx. 42 mN/m | Strong wetting and spreading capability |
| CMC (Critical Micelle Concentration) | Approx. 0.005% | Forms micelles at very low dosage, high solubilization efficiency |
Application Recommendations
General Dissolution/Dispersion Methods
Method One (Aqueous Phase Hot Dissolution, Recommended): Heat the required amount of deionized water to 60-70°C, slowly add SG-40 solid particles or melt under low-speed stirring. Continue stirring until completely dissolved, forming a clear or slightly opalescent solution, then cool to the temperature required by the process before adding the oil phase or other components for emulsification and homogenization. This method is particularly suitable for directly preparing concentrates for toners, pesticide aqueous solutions, or metalworking fluids.
Method Two (Oil Phase Hot Melt): Mix SG-40 with the oily components in the formula (such as mineral oil, silicone oil, ester oils), stir and heat to 55-65°C until it completely melts and dissolves. Simultaneously heat the aqueous phase to a similar temperature, then slowly draw the oil phase into the aqueous phase under high-speed homogenization to perform emulsification. Creams or lotions prepared by this method exhibit better stability.
Recommended Dosages for Various Fields
- Cosmetic Creams/Lotions (O/W type): Recommended dosage 1.0% – 3.0% (of total formulation). Often used synergistically with Glyceryl Monostearate or fatty alcohols for thickening, achieving a light, non-greasy skin feel. In shampoos and shower gels, as a solubilizer and conditioning agent, dosage is about 0.5% – 2.0%.
- Textile Softeners/Antistatic Agents: Recommended dosage 2.0% – 5.0%. Can be used to prepare yarn treatment solutions or finishing working solutions, imparting excellent softness and smooth handle to synthetic fibers and blended fabrics, while reducing static electricity accumulation.
- Metalworking Fluids (Emulsifiable Oil/Semi-synthetic Cutting Fluids): Recommended dosage 2.0% – 5.0%. Used in combination with Sodium Petroleum Sulfonate, Tall Oil, etc., significantly enhancing emulsion stability, detergency, and extreme pressure lubricity, preventing cutting fluid spoilage and separation.
- Pesticide Aqueous Emulsions (EW)/Microemulsions (ME): Recommended dosage 3.0% – 8.0% (of total formulation). As the primary emulsifier, used with anionic emulsifiers (like calcium salts), it achieves efficient emulsification and dispersion for organophosphorus and pyrethroid technicals, improving the wetting and spreading properties of the spray solution on leaf surfaces.
- Paper Deinking Agents: Recommended dosage 0.5% – 2.0% (based on oven-dry pulp weight). Promotes the detachment of ink from fiber surfaces and its flocculation removal during the flotation deinking process, while improving the softness of the recycled paper sheet.
Precautions
- Temperature Control: Long-term storage temperature should be controlled between 5°C and 35°C. During processing, heating temperature should not exceed 80°C to avoid hydrolysis of ester bonds or color deepening caused by prolonged high temperatures.
- Moisture-proof Sealing: SG-40 is slightly hygroscopic; reseal promptly after opening. If the product clumps due to improper storage and moisture absorption, its chemical activity is unaffected, but drying or extending stirring time in hot water for dissolution before use is recommended.
- Water Quality Requirements: The product has excellent hard water tolerance; however, when formulating transparent microemulsions or high-stability emulsions, using deionized water is recommended to reduce potential interference from calcium and magnesium ions on conductivity or light transmittance.
- Synergistic Compounding: For optimal emulsification, compounding with low HLB emulsifiers (like SG-6, HLB≈9-11) based on HLB value matching principles is recommended. The ratio can be determined by calculating the required HLB value of the target oil phase; typically, SG-40 constitutes 20%–40% of the total emulsifier amount.
- Safe Handling: Although the product is non-toxic and non-irritating, wearing protective gloves and goggles during handling is still advised to avoid burns from molten material and dust inhalation. Maintain good ventilation at the worksite (data sourced from Guoli Chemical Product Safety Instructions).
