Detergent-sulfonates are a type of surfactant compound that helps remove dirt, grease, and other deposits from surfaces and fabrics. They work by helping to reduce surface tension and act as a wetting agent. They are commonly used in industrial cleaners and lubricants.
As a lubricant additive, detergent-sulfonates help reduce friction and improve overall performance and wear resistance of the lubricant.
Sulfonates, specifically detergent-sulfonates, are a type of additive commonly used in lubricants. They are typically derived from petroleum sulfonic acids and are widely used due to their excellent detergent and dispersant properties. The main function of detergent-sulfonates in lubricants is to keep the engine or machinery clean by preventing the formation of deposits, sludge, and varnish.
Here are some key benefits and functions of detergent-sulfonates in lubricants:
- Dispersancy: Detergent-sulfonates have excellent dispersancy properties, meaning they can keep contaminants, such as soot, carbon, and combustion by-products, in suspension within the oil. By preventing the solid particles from agglomerating and settling, detergent-sulfonates help maintain cleaner engine internals and parts.
- Deposit and sludge prevention: Detergent-sulfonates form a protective barrier on metal surfaces, preventing the adhesion and formation of deposits, sludge, and varnish. This helps to keep critical engine components, such as pistons, rings, and valves, free from harmful deposits that can affect engine performance and efficiency.
- Engine cleanliness: Detergent-sulfonates play a crucial role in maintaining engine cleanliness by effectively removing and dispersing harmful contaminants. They can clean up existing deposits and prevent the formation of new ones, ensuring the optimal performance and longevity of the engine.
- Wear protection: By keeping the engine or machinery clean, detergent-sulfonates indirectly provide wear protection. By minimizing the presence of contaminants and deposits, the lubricant can better form a protective film between metal surfaces, reducing friction and wear.
Overall, detergent-sulfonates in lubricants offer multiple benefits in terms of maintaining engine cleanliness, preventing deposits and sludge, promoting dispersancy, and providing wear protection. By using lubricants with detergent-sulfonate additives, equipment owners can ensure smoother operation, longer service intervals, and reduced maintenance costs.
🧪 Lubricant Detergent – Sulfonate Type (Calcium or Magnesium Sulfonates)
Sulfonates are one of the most important detergent additives used in lubricating oils, especially for internal combustion engines, marine oils, and heavy-duty diesel oils.
🧴 What Are Sulfonate Detergents?
Sulfonate detergents are metal salts of alkylbenzene sulfonic acids, typically with:
- Calcium (Ca) – Most common
- Magnesium (Mg)
- Sodium (Na) – Rare in modern lubes
🔬 Structure:
They typically look like this:R–C6H4–SO3⁻ M⁺
Where:
R= long alkyl chain (oil-soluble)C6H4–SO3= benzene sulfonate group (polar, detergent action)M= metal ion (Ca²⁺, Mg²⁺)
⚙️ Main Functions in Lubricants:
| Function | Description |
|---|---|
| Detergency | Cleans piston and engine surfaces by removing carbon, varnish, soot |
| Neutralization | Reacts with acidic combustion byproducts (like sulfuric acid from fuel) |
| Dispersancy | Helps suspend sludge and soot particles in oil (if overbased) |
| Anti-corrosion | Protects engine internals from acid attack |
🔄 Types of Sulfonates:
| Type | Description |
|---|---|
| Neutral | Basic cleaning and acid-neutralizing ability |
| Overbased | Contains excess metal base (e.g., CaCO₃), gives much higher TBN (alkalinity) |
- TBN (Total Base Number) of overbased types can range from 200–400+ mg KOH/g.
- Overbased sulfonates also have micellar structures that absorb acids.
🏭 Production of Calcium Sulfonate Detergent (Simplified):
- Alkylation of benzene → produces alkylbenzene.
- Sulfonation with SO₃ → alkylbenzene sulfonic acid.
- Neutralization with Ca(OH)₂ or CaCO₃ → calcium sulfonate.
- Overbasing (optional):
- Add excess lime and CO₂ to form dispersed CaCO₃ micelles in oil.
🧪 Example Specifications:
| Property | Typical Value |
|---|---|
| Appearance | Amber to dark brown viscous liquid |
| Base oil diluent | Mineral oil or synthetic |
| TBN (overbased) | 250–400 mg KOH/g |
| Calcium content | ~3–10% |
| Viscosity @100°C | Varies, ~50–150 cSt |
| Solubility | Oil-soluble |
🛢️ Applications:
- Engine oils (PCMO, HDMO)
- Marine lubricants (low/high sulfur fuels)
- Industrial oils (gear, hydraulic with acid exposure)
- Greases (e.g., calcium sulfonate complex greases)
- Metalworking fluids
✅ Advantages:
- Excellent high-temperature detergency
- Strong acid-neutralizing power
- Good rust protection
- Compatible with other additives (e.g., dispersants, ZDDP)
⚠️ Considerations:
- Must be blended properly to avoid ash buildup in engine
- Compatibility with emission control systems (like DPF) requires low-ash formulations (low Ca levels)