📋 In This Article
- What Are Sorbitan Esters?
- Chemistry: How Structure Drives HLB and Function
- The Complete Span Family: Grades, HLB, and Properties
- Span 20 (Sorbitan Monolaurate) - Deep Dive
- Span 60 (Sorbitan Monostearate) - Deep Dive
- Span 80 (Sorbitan Monooleate) - Deep Dive
- Span + Polysorbate Pairing Strategy
- Applications Across Industries
- How to Choose the Right Span Grade
- Quality Specifications and Sourcing
- FAQ
- Contact Sinolook Chemical
🌿 1. What Are Sorbitan Esters?
Sorbitan esters are produced by the esterification of sorbitol (a sugar alcohol) with a fatty acid under controlled dehydration conditions. During the reaction, sorbitol loses one or two molecules of water to form a cyclic ring structure called sorbitan or isosorbide, which then reacts with the fatty acid to yield the ester product.
The resulting molecules are non-ionic surfactants - they carry no electrical charge - with a characteristic split personality: the sorbitan ring system provides limited hydrophilicity through its remaining hydroxyl groups, while the fatty acid chain (C12 to C18) provides the lipophilic tail. This amphiphilic structure makes sorbitan esters highly effective at adsorbing to oil-water interfaces and stabilizing emulsions.
💡 The "Span" Trade Name
"Span" was originally a registered trade name of Atlas Chemical Industries (later ICI, then Uniqema, now Croda). Today it has become a generic descriptor used throughout the chemical industry. When you see "Span 80" on a CoA or formulation sheet, it always refers to sorbitan monooleate regardless of which manufacturer produced it. The same applies to Span 20, Span 40, Span 60, Span 83, and Span 85.
Sorbitan esters occupy the lipophilic end of the non-ionic emulsifier spectrum - their HLB values range from 1.8 (Span 85, highly lipophilic) to 8.6 (Span 20, moderately hydrophilic). This places them firmly in the water-in-oil emulsifier and wetting agent categories. For oil-in-water emulsification, they are typically combined with their ethoxylated counterparts - the polysorbates (Tween series) - to hit a higher blended HLB.
⚗️ 2. Chemistry: How Structure Drives HLB and Function
Two structural variables determine everything about a sorbitan ester's performance:
Variable 1: Fatty Acid Chain Length
The fatty acid esterified with sorbitan determines the lipophilicity and physical state of the product. Shorter chains (C12 lauric) produce lower-melting, more polar esters; longer chains (C18 stearic) produce higher-melting, more lipophilic solids.
- C12 (Lauric) → Span 20, HLB 8.6, liquid
- C16 (Palmitic) → Span 40, HLB 6.7, solid
- C18:0 (Stearic) → Span 60, HLB 4.7, solid
- C18:1 (Oleic) → Span 80, HLB 4.3, liquid
- C18:1 ×3 (Trioleate) → Span 85, HLB 1.8, liquid
Variable 2: Degree of Esterification
The sorbitan ring has multiple hydroxyl groups available for esterification. Mono-esters (one fatty acid per sorbitan) are more hydrophilic; sesqui-esters (1.5 fatty acids) and tri-esters (three fatty acids) are more lipophilic.
- Monoester → Span 20, 40, 60, 80 - 1 fatty acid chain
- Sesquiester → Span 83 - 1.5 oleate chains average
- Triester → Span 85 - 3 oleate chains, very lipophilic
Moving from mono → tri reduces HLB by blocking hydroxyl groups and adding lipophilic mass.
💡 The Unsaturation Effect: Why Span 80 Stays Liquid
Span 60 (stearate, C18:0) and Span 80 (oleate, C18:1) have nearly identical HLB values (4.7 vs 4.3), but Span 60 is a waxy solid at room temperature while Span 80 is a viscous liquid. The single double bond in the oleate chain disrupts molecular packing and lowers the melting point dramatically - from ~50 °C (Span 60) to well below 0 °C (Span 80). This physical state difference is the primary reason Span 80 is far more widely used in ambient-temperature manufacturing processes.
📊 3. The Complete Span Family: Grades, HLB, and Properties
| Grade | Chemical Name | Fatty Acid | HLB | State (25 °C) | CAS | Primary Function |
|---|---|---|---|---|---|---|
| Span 20 | Sorbitan Monolaurate | C12 Lauric | 8.6 | Liquid | 1338-39-2 | Wetting agent, emulsifier for polar oils |
| Span 40 | Sorbitan Monopalmitate | C16 Palmitic | 6.7 | Solid ~45 °C | 26266-57-9 | W/O emulsifier, thickener in hot systems |
| Span 60 | Sorbitan Monostearate | C18:0 Stearic | 4.7 | Solid ~50 °C | 1338-41-6 | W/O emulsifier, food E491, pharma |
| Span 80 ★ | Sorbitan Monooleate | C18:1 Oleic | 4.3 | Liquid | 1338-43-8 | Most widely used - W/O emulsifier, multi-industry |
| Span 83 | Sorbitan Sesquioleate | C18:1 ×1.5 Oleic | 3.7 | Liquid | 8007-43-0 | W/O emulsifier where lower HLB than 80 needed |
| Span 85 | Sorbitan Trioleate | C18:1 ×3 Oleic | 1.8 | Liquid | 26266-58-0 | Extreme W/O, oilfield invert mud, specialty |
HLB Spectrum of the Span Series
← More lipophilic (W/O) More hydrophilic (wetting) →
🔬 4. Span 20 (Sorbitan Monolaurate) - Deep Dive
Span 20 is the most hydrophilic member of the sorbitan ester family, with an HLB of 8.6. This places it at the boundary between the wetting agent zone (HLB 7–9) and the lower end of the O/W emulsifier range. The lauric acid chain (C12) is shorter and more polar than the longer-chain variants, which accounts for the higher hydrophilicity.
| Property | Value |
|---|---|
| INCI / Chemical Name | Sorbitan Laurate |
| HLB | 8.6 |
| Appearance | Amber liquid, low viscosity |
| Molecular Weight | ~346.5 g/mol |
| Solubility | Dispersible in warm water; soluble in most oils and solvents |
| Polysorbate counterpart | Tween 20 (Polysorbate 20), HLB 16.7 |
Key Applications of Span 20
- 🧴 Cosmetics: Wetting agent in cleansing formulations; co-emulsifier in O/W lotions when blended with Tween 20; spreading agent in spray formulations
- 🌾 Agriculture: Wetting and spreading agent in foliar sprays; improves coverage on hydrophobic leaf surfaces
- 💊 Pharma: Wetting agent in tablet coating systems; emulsifier in topical formulations requiring moderate HLB
- 🧪 Laboratory: Membrane protein solubilization; cell lysis buffer component in biological research
✅ When to choose Span 20 over Span 80: When you need an oil-soluble emulsifier with higher HLB for moderately polar oil phases, or when the formulation pH is low and Tween 20/Span 20 co-emulsifier combinations are specified. Span 20 is also the standard choice when the end application requires a lauric acid-derived sorbitan ester specifically (e.g., certain antimicrobial or membrane-active applications).
🔬 5. Span 60 (Sorbitan Monostearate) - Deep Dive
Span 60 - sorbitan monostearate (CAS 1338-41-6) - is the food-grade workhorse of the Span family. With an HLB of 4.7, it sits just above Span 80 on the lipophilicity scale, but its saturated stearic acid chain makes it a waxy cream-coloured solid with a melting point of approximately 50–55 °C. This physical form demands hot-process incorporation but also provides unique structural and textural benefits that liquid sorbitan esters cannot deliver.
| Property | Value |
|---|---|
| INCI / Chemical Name | Sorbitan Stearate |
| Food Additive Number | E491 (EU food emulsifier) |
| HLB | 4.7 |
| Appearance | Cream/white waxy solid, mp ~50–55 °C |
| Molecular Weight | ~430.6 g/mol |
| Acid Value | ≤ 7.5 mg KOH/g |
| Polysorbate counterpart | Tween 60 (Polysorbate 60), HLB 14.9 |
Key Applications of Span 60
- 🍞 Food (E491): Crumb softener and anti-staling agent in yeast-raised baked goods; defoamer in fermentation; crystal modifier in chocolate coatings and icings; dough conditioner
- 💊 Pharmaceuticals: W/O emulsifier in ointments and creams; tablet lubricant and binder in hot-melt granulation; suppository base component; aerosol propellant valve lubricant
- ✨ Cosmetics: Emulsion stabilizer and consistency factor in creams formulated via hot process; contributes a waxy, rich texture to body butters and balms; W/O sunscreen emulsifier
- 🔧 Industrial: Textile fiber lubricant in synthetic fiber production; antifoaming agent in industrial fermentation; paper sizing additive
⚠️ Span 60 vs Span 80: When the Solid State Is an Advantage
In hot-process cosmetic formulations (creams, balms, ointments processed above 60 °C), Span 60 offers a practical advantage: it contributes both emulsification and a solid structural component that thickens and adds body to the formulation on cooling. A W/O cream using Span 60 + Tween 60 will typically have a firmer, richer texture than the same formula using Span 80 + Tween 80. For room-temperature processes, Span 80 remains the practical choice.
🔬 6. Span 80 (Sorbitan Monooleate) - Deep Dive
Span 80 is the most commercially important sorbitan ester by volume and the one most formulators encounter first. Its combination of an HLB of 4.3, liquid state at room temperature, and broad compatibility with diverse oil phases makes it the default W/O emulsifier choice across pharmaceuticals, cosmetics, agriculture, oilfield chemistry, and industrial processing.
| Property | Value |
|---|---|
| INCI Name | Sorbitan Oleate |
| HLB | 4.3 |
| Appearance | Amber viscous liquid (pourable at RT) |
| Viscosity (25 °C) | ~1,000–1,200 mPa·s |
| Flash Point | > 200 °C |
| Polysorbate counterpart | Tween 80 (Polysorbate 80), HLB 15.0 |
| Key advantage over Span 60 | Liquid at room temperature - no heating required for incorporation |
Why Span 80 Dominates the Market
Three factors explain Span 80's market dominance over other Span grades:
Liquid at ambient temperature
Unlike Span 40, 60, and the solid grades, Span 80 requires no melting. It can be pumped, metered, and incorporated into batch systems at room temperature - a critical manufacturing advantage in continuous or cold-process operations.
HLB 4.3 is the optimal W/O sweet spot
Most mineral, silicone, and vegetable oil phases have a required W/O HLB of 3–5. Span 80's HLB 4.3 sits perfectly in the middle of this range, making it effective across a wider variety of oil phases without HLB adjustment.
Perfect complement to Tween 80
The Span 80 / Tween 80 pair shares the same oleate fatty acid chain. This structural compatibility produces exceptionally strong mixed interfacial films when the two co-adsorb at the oil-water interface - a stability advantage over mismatched Span/Tween pairs.
For full technical details, HLB calculations, and application examples for Span 80, see our dedicated SPAN 80 (Sorbitan Monooleate) product page.
⚗️ 7. Span + Polysorbate Pairing Strategy
Each Span grade has a structurally matched polysorbate (Tween) counterpart produced by ethoxylation. Using matched pairs - same fatty acid chain in both emulsifiers - produces the most synergistic interfacial film because the two molecules pack together more effectively at the droplet surface.
| Span Grade (HLB) | Matched Tween (HLB) | HLB Range Covered | Best Emulsion Type | Typical Industries |
|---|---|---|---|---|
| Span 20 (8.6) | Tween 20 (16.7) | 8.6–16.7 | O/W, wetting | Cosmetics, pharma, agriculture, lab |
| Span 60 (4.7) | Tween 60 (14.9) | 4.7–14.9 | W/O and O/W | Food, pharma ointments, cosmetics (hot process) |
| Span 80 (4.3) ★ | Tween 80 (15.0) | 4.3–15.0 | W/O, O/W, and all intermediate types | Most widely used pair across all industries |
| Span 85 (1.8) | Tween 85 (11.0) | 1.8–11.0 | Extreme W/O | Oilfield, specialty industrial |
🏭 8. Applications Across Industries
💊 Pharmaceuticals
- Span 80: W/O topical drug delivery, vaccine adjuvant emulsions, invert emulsion injectables
- Span 60: Ointment bases, suppository formulations, hot-process cream emulsifier
- Span 20: Wetting agent in tablet coatings, solubilizer for poorly soluble drugs
- All grades: USP/NF or equivalent pharma grade available
✨ Cosmetics & Personal Care
- Span 80: W/O sunscreens, cold creams, pigment dispersant in color cosmetics
- Span 60: Rich W/O creams, body butters, hot-process emulsions requiring firm texture
- Span 20: O/W light emulsions, wetting agent in toners and serums
🍞 Food Processing
- Span 60 (E491): Bread softener, cake crumb improver, chocolate anti-bloom, yeast anti-clump
- Span 80 (E494): Limited food use as defoamer and emulsifier in certain applications
- Food grade requires specific purity and certifications per regional food law
🌾 Agriculture
- Span 80: Emulsifiable concentrate (EC) formulation, spreader-sticker in sprays
- Span 20: Wetting agent on hydrophobic plant surfaces, uptake enhancer
- Both used as adjuvants in oil-based pesticide and herbicide formulations
⛽ Oilfield & Industrial
- Span 80: Invert drilling mud emulsifier, corrosion inhibitor carrier, mold release emulsifier
- Span 85: Heavy-duty invert emulsions requiring very low HLB
- Both: metalworking fluid components, rust-preventive oil formulations
🧵 Textiles & Others
- Span 60: Fiber lubricant and anti-static agent in synthetic fiber spinning
- Span 80: Textile softening bath emulsifier, leather processing fat-liquoring
- Both used in paper processing and ink formulations
🎯 9. How to Choose the Right Span Grade
Use this framework as your starting point - match your process conditions and performance requirements:
📊 10. Quality Specifications and Sourcing
Quality parameters for sorbitan esters are broadly consistent across grades. The critical parameters to verify on your incoming CoA are:
| Parameter | Span 20 | Span 60 | Span 80 | Significance |
|---|---|---|---|---|
| Acid Value (mg KOH/g) | ≤ 7.0 | ≤ 7.5 | ≤ 8.0 | Free fatty acid - indicates freshness and process quality |
| Saponification Value (mg KOH/g) | 158–170 | 147–157 | 145–160 | Ester content confirmation - identity test |
| Hydroxyl Value (mg KOH/g) | 330–358 | 235–260 | 193–210 | Degree of esterification - affects HLB and surface activity |
| Water Content (KF, %) | ≤ 1.5 | ≤ 1.0 | ≤ 1.0 | Hydrolysis prevention; clouding in liquid grades |
| Heavy Metals (ppm) | ≤ 10 | ≤ 10 | ≤ 10 | Required for pharma and food-grade applications |
| Colour (Gardner) | ≤ 6 | ≤ 3 (white solid) | ≤ 8 | Relevant for cosmetic and light-colored formulations |
✅ Supplier Checklist for Sorbitan Esters
- ✅ Batch-specific CoA provided for every shipment?
- ✅ Feedstock origin confirmed - vegetable (coconut / palm / sunflower)?
- ✅ Halal and / or Kosher certification available for food and pharma supply?
- ✅ Food-grade certificate (E491 compliance) for Span 60 food applications?
- ✅ REACH registration in place for EU shipments?
- ✅ Packaging options available: drums (180 kg), IBC (1,000 kg), ISO tank?
- ✅ Samples available (1–5 kg) for formulation trials before bulk commitment?
❓ 11. Frequently Asked Questions
📦 Source Sorbitan Esters from Sinolook Chemical
Sinolook Chemical supplies SPAN 80 (Sorbitan Monooleate) and other sorbitan ester grades in industrial, cosmetic, food, and pharmaceutical quality. Full documentation - batch CoA, MSDS, REACH registration, Halal/Kosher certification on request, and HS code declarations - is provided with every shipment. Minimum order 200 kg; samples available for qualified customers.
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www.sinolookchem.com🔗 Related Products: SPAN 80 Product Page · PEG Oleate · Cocamide DEA · Oleate Esters Category
