OP-4, full chemical name octylphenol polyoxyethylene (4) ether (CAS No.: 9036-19-5), molecular formula C₈H₁₇C₆H₄O(CH₂CH₂O)nH (n≈4), molecular weight about 382, is a high-purity (active content ≥99%) nonionic surfactant produced by Guoli Chemical. The product is synthesized by condensing octylphenol with 4 moles of ethylene oxide. The hydrophobic octylphenyl group combined with a short-chain polyoxyethylene hydrophilic group gives it a low HLB value (8.8). It is insoluble in water and exists in a dispersed state, but is soluble in oils and most organic solvents.
The most prominent core characteristic of this product is its excellent water-in-oil (W/O) emulsifying ability, which can stably disperse water droplets in the oil phase, while also possessing good wetting and dispersing properties. It exhibits excellent chemical stability in acidic, alkaline, and hard water media, and produces extremely low foam, making it especially suitable for industrial processes requiring foam control. The product has low hygroscopicity, a flash point above 150°C, and is stable under normal storage conditions. Oral (rat) LD₅₀ >2000 mg/kg, classified as low toxicity, but it is irritating to skin and eyes (H315/H319) and has aquatic ecotoxicity (H410). Strict operation procedures and waste disposal according to regulations are required.
With its unique lipophilic-hydrophilic balance characteristics, OP-4 plays a key role in multiple industrial fields: as a pesticide emulsifier to improve spreading and penetration; as a textile printing and dyeing penetrant and leveling agent to shorten pretreatment time and prevent uneven dyeing; in oilfield chemicals for heavy oil viscosity reduction and crude oil demulsification; suitable for industrial heavy-duty cleaners and leather degreasing formulations; providing emulsification and lubrication in metalworking fluids; and also as an important starting material for synthesizing anionic surfactants such as sulfate esters and sulfonates.
| Parameter Item | Technical Index |
|---|---|
| Ionic Type | Nonionic |
| Appearance (25°C) | Pale yellow to yellow oily liquid |
| Active Content | ≥99% |
| HLB Value | 8.8 |
| Cloud Point | None (insoluble in water) |
| Hydroxyl Value | 145~155 mg KOH/g |
| pH Value (1% aqueous dispersion) | 5.0~7.0 |
| Moisture Content | ≤1.0% |
| Density (25°C) | 1.02~1.04 g/cm³ |
| Kinematic Viscosity (25°C) | ~300 mPa·s |
| Refractive Index (20°C) | 1.490~1.500 |
| Acid Value | ≤1 mg KOH/g |
| Iodine Value | ≤0.5 gI₂/100g |
| Surface Tension (1% aqueous dispersion, 25°C) | ~28 mN/m |
| Critical Micelle Concentration CMC (25°C) | ~1.1×10⁻⁴ mol/L |
| Melting Point | ＜0°C |
| Flash Point | ＞150°C |
| Solubility | Soluble in oils and organic solvents, dispersible in water |
| Foaming Property | Low foaming |
Pesticide Emulsifier: It is recommended as an emulsifying component in emulsifiable concentrates and emulsion formulations of organophosphorus and pyrethroid pesticides. Utilizing its W/O emulsifying ability, it improves the dispersion uniformity of the active ingredient in water and enhances the wetting and spreading ability of the spray liquid on plant leaf surfaces. It is suggested to determine the optimal dosage through HLB matching experiments of the active ingredient and solvent system. The general reference dosage is 3%~10% of the total formulation weight.
Textile Printing and Dyeing Auxiliaries: Used as a penetrant in pretreatment processes, it can quickly promote the penetration of alkali liquor and bleaching liquor into the fiber interior, shortening treatment time and improving uniformity. Used as a leveling agent in high-temperature and high-pressure dyeing to slow down the dye uptake rate and prevent uneven dyeing and spots. Recommended dosage is 0.5~2 g/L of the working solution weight.
Industrial Cleaning and Leather Degreasing: Suitable for formulating metal parts degreasers and hard surface cleaners, with strong emulsifying and dispersing ability for mineral oils and greases. In leather degreasing processes, it is recommended to add during liming or bating stages at a ratio of 0.5%~1.5% of the leather weight, combined with nonionic or anionic systems.
Metalworking Fluids: Plays an emulsifying and lubricating role in cutting fluid and grinding fluid formulations, helping to form stable water-in-oil microemulsions, reducing friction, and extending tool life. It is recommended as a main emulsifier component, combined with rust inhibitors and extreme pressure additives, optimized within a dosage range of 5%~15%.
Anionic Surfactant Intermediate: This product is a key starting material for synthesizing anionic surfactants such as sulfate esters and sulfonates. Through sulfonation or sulfation reactions, sulfate/sulfonate groups can be introduced to prepare anionic surfactant series for daily use and industrial applications.
Safety Risks: This product is irritating to skin and eyes (H315/H319). During operation, impermeable gloves, protective clothing, and chemical safety goggles must be worn. It is highly toxic to aquatic life with long-lasting effects (H410). It is strictly prohibited to discharge the product or wastewater containing it directly into surface water or groundwater.
Handling and Storage: Ensure good ventilation in the operation area, equipped with eyewash stations and emergency showers. Store in a dry, cool warehouse at 5°C~40°C, keep containers tightly closed, and away from strong oxidizers, strong acids, and heat sources.
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