Stearic Acid Polyoxyethylene Ether SG-40 (CAS: 9004-99-3), chemically known as Polyoxyethylene (40) Stearate, also goes by the names PEG-40 Stearate and Emulsifier SG-40. Its molecular formula is RO(CH₂CH₂O)ₙH (R = C16-18 fatty chain, n = 40), with an average molecular weight of approximately 2045, and it belongs to the category of nonionic surfactants. The product has an active content of ≥99%, appears as a white to pale yellow waxy solid at room temperature, with a melting point range of 48-52°C. It is readily soluble in water and various organic solvents, has low hygroscopicity, and exhibits stable chemical properties, being resistant to acids, alkalis, and hard water.
In terms of surface activity, SG-40 has an HLB value as high as 16-17, making it a hydrophilic emulsifier suitable for O/W (oil-in-water) systems. Its critical micelle concentration (CMC) is approximately 0.005%, and the surface tension of a 1% aqueous solution at 25°C is about 42 mN/m. The cloud point exceeds 100°C, and the pH values of both 1% and 5% aqueous solutions are 5.0-7.0, indicating a weakly acidic to neutral range. It exhibits low foam characteristics, which can reduce the need for defoamers in practical applications.
Regarding component purity, the product has a monoester content of ≥90%, diester content of ≤5%, free alcohol of ≤1%, moisture of ≤1.0%, acid value of ≤2 mgKOH/g, saponification value of 25-35 mgKOH/g, hydroxyl value of approximately 28 mgKOH/g, and iodine value of ≤1 gI₂/100g (indicating extremely low unsaturation). Heavy metal content is ≤10 mg/kg, and arsenic content is ≤2 mg/kg, meeting strict impurity control requirements for daily chemical and industrial auxiliaries.
| Parameter Item | Specification / Indicator |
|---|---|
| Product Name / Full Chemical Name | Stearic Acid Polyoxyethylene Ether SG-40 / Polyoxyethylene (40) Stearate |
| Synonyms | PEG-40 Stearate, Emulsifier SG-40, Polyethylene Glycol (40) Stearate |
| CAS Number | 9004-99-3 |
| Ionic Type | Nonionic |
| Molecular Formula | RO(CH₂CH₂O)ₙH (R=C16-18, n=40) |
| Average Molecular Weight | Approximately 2045 |
| Appearance (Room Temperature) | White to pale yellow waxy solid |
| Active Content (Solid Content) | ≥99% |
| Melting Point | 48-52°C |
| Density | Approximately 1.05 g/cm³ |
| Refractive Index (60°C) | Approximately 1.456 |
| Flash Point (Closed Cup) | >200°C |
| Solubility | Readily soluble in water and organic solvents |
| Hygroscopicity | Low |
| Chemical Stability | Resistant to acids, alkalis, and hard water; stable properties |
| HLB Value | 16-17 |
| Cloud Point | >100°C |
| Critical Micelle Concentration (CMC) | Approximately 0.005% |
| Surface Tension (1% Aqueous Solution, 25°C) | Approximately 42 mN/m |
| Foam Characteristics | Low foam |
| pH (1% Aqueous Solution) | 5.0-7.0 |
| pH (5% Aqueous Solution) | 5.0-7.0 |
| Acid Value | ≤2 mgKOH/g |
| Saponification Value | 25-35 mgKOH/g |
| Hydroxyl Value | Approximately 28 mgKOH/g |
| Iodine Value | ≤1 gI₂/100g (extremely low unsaturation) |
| Moisture Content | ≤1.0% |
| Monoester Content | ≥90% |
| Diester Content | ≤5% |
| Free Alcohol | ≤1% |
| Heavy Metals (as Pb) | ≤10 mg/kg |
| Arsenic (As) | ≤2 mg/kg |
| Kinematic Viscosity | Not applicable (solid at room temperature) |
| Packaging Specification | 20kg woven bag |
(Data source: Guoli Chemical Product Database)
Based on SG-40's high HLB value (16-17) and excellent water solubility, it is primarily used as an O/W emulsifier in the following fields: