What is Span S-40? What are its main uses?

Span S-40 (Sorbitan monopalmitate) is a pale yellow waxy nonionic surfactant. Its core function is as a W/O (water-in-oil) emulsifier, while also possessing excellent dispersing, wetting, and stabilizing properties. It is widely used in many industrial fields such as cosmetics, food, pharmaceuticals, pesticides, textiles, plastics, and coatings.

Detailed Description

Span S-40, chemical name Sorbitan monopalmitate (CAS No.: 26266-57-9), belongs to the nonionic surfactant category. It appears as a pale yellow waxy solid and is produced by Haian Guoli Chemical Co., Ltd. As a member of the classic Span series of emulsifiers, Span S-40 is prepared by the esterification reaction of sorbitol and palmitic acid. Its molecular structure contains polyol hydrophilic groups and long-chain fatty acid hydrophobic groups, granting it unique water-in-oil emulsifying capability.

This product exhibits several outstanding characteristics: excellent emulsifying performance, capable of forming stable W/O emulsions; superior chemical stability, resistant to acids, alkalis, and hard water, maintaining reliable performance in complex systems; broad compatibility, allowing good combination with various ionic and nonionic additives, providing strong formulation adaptability; high safety, classified as practically non-toxic (rat acute oral LD₅₀ > 10 g/kg), with a primary skin irritation index of 0, non-irritating and non-mutagenic.

In practical formulations, Span S-40 is often used in combination with Tween series (e.g., Tween-40). By adjusting the ratio, a composite emulsifier system with different HLB values can be obtained, meeting the needs of various emulsion types from W/O to O/W, making it an essential raw material in fine chemical formulations.

Technical Parameters

Application Recommendations

Span S-40 is mainly applied across seven industrial sectors:

• Cosmetics and Personal Care: Used as an excellent W/O emulsifier, capable of forming stable emulsions and creams with a fine skin feel. It is a common emulsifying component in facial creams, sunscreens, foundations, and similar products.
• Food Industry: Used as an emulsifier, stabilizer, and defoamer, often added to bakery fats, whipped creams, and protein beverages to enhance system stability. It complies with food additive standards such as FDA 21 CFR 172.842.
• Pharmaceutical Preparations: Used as a pharmaceutical excipient, serving as an emulsifying base for creams and suppositories to improve drug dispersion uniformity and bioavailability.
• Pesticide Eco-friendly Formulations: Used as an emulsifier and dispersant in emulsifiable concentrates, water emulsions, and suspension concentrates to enhance the wetting and spreading performance of the liquid on plant surfaces.
• Textile Industry: Used as a softener and antistatic agent, imparting good smoothness, cohesion, and antistatic properties to fibers in spin finishes.
• Plastic Industry: Used as an internal antistatic agent and anti-fog additive, which can migrate to the surface of plastic films to effectively eliminate static electricity and prevent water droplet condensation that affects light transmittance.
• Coatings and Inks: Used as an efficient pigment dispersant, significantly reducing grinding time, preventing pigment particle flocculation and reagglomeration, thereby enhancing color strength.

Precautions

Good industrial hygiene practices should be followed during handling. Avoid generation and inhalation of dust. If dust may be generated, it is recommended to wear a particulate respirator and safety goggles. Store in a cool (preferably below 35°C), dry, and well-ventilated warehouse, keeping containers tightly sealed and away from strong oxidizers and strong acids. In case of eye contact, flush with plenty of water for at least 15 minutes and seek medical attention if discomfort persists. The product is stable under recommended storage conditions and does not undergo hazardous polymerization reactions.