Lubricant Additives - Sulfurized Alkylphenate Detergents Series: Medium TBN Ca Alkylphenate (TBN 120–180 mgKOH/g, C₁₅H₂₃O₂S₂Ca) is the primary phenate detergent for heavy-duty diesel engine oils, marine engine oils, and gas engine oils - delivering substantially more TBN per treat rate than the Low TBN grade while retaining the built-in disulfide-bridge antioxidant function unique to the alkylphenate chemical class. Sinolook supplies: Low TBN · Medium TBN Ca Alkylphenate · High TBN Ca Alkylphenate.
Lubricant Additive · Sulfurized Alkylphenate · TBN 120–180 · HDEO · Marine · Gas Engine · Industrial Lubricant
Medium TBN Calcium Sulfurized Alkylphenate
TBN 120–180 mgKOH/g / Ca 3–9 wt% / C₁₅H₂₃O₂S₂Ca / HDEO · Marine Engine Oil · Gas Engine · Industrial Lubricant Co-Detergent
| Chemical Formula | C₁₅H₂₃O₂S₂Ca - empirical formula at the repeating alkylphenate unit level; molecular structure: Ca²⁺ coordinated to two alkylphenate oxygens, disulfide (–S₂–) bridges linking alkylphenol dimers; C₁₂–C₁₅ alkyl side chains; in mineral oil diluent |
| Overbasing Level | Medium overbased - higher Ca(OH)₂ / CaCO₃ loading than Low TBN grade; colloidal alkalinity reserve comparable to medium-TBN Ca sulfonate; structure: Ca-phenate + dispersed basic Ca species |
| TBN Range | 120–180 mgKOH/g (ASTM D2896; grade-specific TBN on COA; customisable sub-grades) |
| Physical State | Clear to dark amber-brown liquid; moderate viscosity (higher than Low TBN grade due to greater Ca loading); warm to 40–60°C in cold climates for comfortable pumping |
| Key Advantage | ★ High TBN + phenolic AO in one component Disulfide EP synergy HDEO / Marine primary phenate |
| GHS Hazards | Combustible liquid FP ≥180°C H315/H319 skin/eye irritant |
What Is Medium TBN Calcium Sulfurized Alkylphenate?
Medium TBN Calcium Sulfurized Alkylphenate (empirical formula C₁₅H₂₃O₂S₂Ca) is the central grade of the calcium alkylphenate TBN series - balancing the maximum-antioxidant / minimum-ash profile of the Low TBN grade with the maximum-TBN / higher-ash profile of the High TBN grade. At TBN 120–180 mgKOH/g, it delivers 3–5× more acid neutralisation per unit treat rate than Low TBN Ca Alkylphenate, making it the preferred phenate grade for applications where substantial TBN is required from the phenate component - most importantly, heavy-duty diesel engine oil (HDEO), marine engine oil, and gas engine oil, all of which target finished oil TBN of 10–18 mgKOH/g and cannot rely solely on Ca sulfonate for the required TBN at acceptable sulphated ash levels.
The molecular formula C₁₅H₂₃O₂S₂Ca reflects the disulfide-bridged (–S₂–) alkylphenate calcium salt structure confirmed in the product image - two sulfur atoms per repeating unit, providing a stronger secondary antioxidant (hydroperoxide decomposition) and EP contribution compared to monosulfide-bridged (–S–) variants. The phenol –OH radical scavenging function remains active at this TBN level, making Medium TBN Ca Alkylphenate genuinely multi-functional: TBN carrier + primary antioxidant + secondary antioxidant + mild EP + detergent + corrosion inhibitor in a single molecule.
| Grade | TBN | Ca Content | Primary Role |
|---|---|---|---|
| Low TBN | 30–80 | 2–8% | PCMO co-detergent; ACEA C-sequence low-SAPS; maximum AO / minimum ash |
| Medium TBN ← This product | 120–180 | 3–9% | HDEO primary phenate; marine engine oil; gas engine; long-drain industrial |
| High TBN | 200–300+ | 8–14% | High-S fuel marine cylinder oil; maximum TBN phenate; offshore / industrial high-acid applications |
Technical Specification
| Parameter | Specification | Test Method | Note |
|---|---|---|---|
| Appearance | Clear to dark amber-brown liquid | Visual | Darker than Low TBN grade due to higher Ca and disulfide content; mild phenol/sulfur odour; haze = check water content |
| Chemical Formula | C₁₅H₂₃O₂S₂Ca | - | Empirical formula at repeating unit level - reflects disulfide (–S₂–) bridging and Ca²⁺ phenate coordination |
| TBN | 120–180 mgKOH/g | ASTM D2896 | Sub-grades at ~120, ~150, ~180 mgKOH/g; specify at order; confirmed on COA |
| Calcium Content | 3–9 wt% | ASTM D5185 / ICP-OES | Grade-dependent; Ca% × 3.40 ≈ S/A%; confirmed on COA for each shipment |
| Sulphur Content | Per disulfide grade (COA) | ASTM D2622 / D5185 | –S₂– structure; higher S/molecule than monosulfide; critical to track in ACEA E9/API FA-4 S-limited formulations |
| Flash Point (COC) | ≥ 180°C | ASTM D92 | Combustible liquid; standard storage; not classified DG under IMDG/ADR/IATA |
| Kinematic Viscosity @100°C | Grade-dependent | ASTM D445 | Typically 20–80 cSt; higher viscosity than Low TBN grade; warm to 40–60°C in cold climates |
| Packaging | 200 kg drum · 1000 L IBC · ISO tank | - | Seal tightly; warm to 40–60°C before pumping if stored below 15°C; 24-month shelf life in original packaging |
Performance Profile
High-Efficiency TBN Delivery with Built-In Antioxidant
At TBN 120–180 mgKOH/g, Medium TBN Ca Alkylphenate delivers 3–5× more acid neutralisation per unit treat rate than the Low TBN grade - enabling HDEO formulators to achieve finished oil TBN of 12–18 mgKOH/g without resorting exclusively to high Ca-content Ca sulfonate detergents that would exceed ACEA E9 or API FA-4 ash limits. Critically, this TBN comes packaged with the phenolic antioxidant function inherent to the alkylphenate chemical class - each mole of phenate TBN is accompanied by a phenol –OH radical scavenging capacity that no Ca sulfonate at any TBN level can match. The combined effect: higher finished oil TBN retention over the drain interval, because the phenate's antioxidant function retards the oxidative acid production that depletes TBN reserve.
Disulfide-Bridge Antioxidant & Sulfur EP Performance
The disulfide (–S₂–) bridges in the C₁₅H₂₃O₂S₂Ca structure provide two sulfur atoms per molecule unit - double the secondary antioxidant capacity of monosulfide-bridged (–S–) phenate variants, and significantly more sulfur EP activity. The –S₂– group decomposes lipid hydroperoxides (ROOH) more rapidly than –S–, reducing the rate of oxidative chain branching in the base oil. Under high mechanical contact stress, the disulfide groups also react sacrificially at metal asperity contacts, providing EP/antiwear film formation analogous to - but less potent than - dedicated sulfur EP gear oil additives. This combination makes Medium TBN Ca Alkylphenate particularly suited for gear oils and industrial lubricants where both antioxidant stability and mild EP protection are valued alongside detergency.
High-Temperature Detergency
The Ca-phenate surfactant complex actively cleans metal surfaces - adsorbing to polar oxidation by-products, carbon deposits, and lacquer precursors, and solubilising them back into the oil phase. At piston undercrown temperatures (typically 180–230°C in diesel engines), Ca alkylphenate provides effective deposit prevention and cleaning. While high-TBN overbased Ca sulfonate has a modest advantage in ring-belt cleanliness at very extreme piston temperatures (>250°C), Ca alkylphenate at medium TBN excels in piston crown land and undercrown deposit control, valve train cleanliness, and turbocharger oil-wetted surface deposit prevention - all standard HDEO deposit tests covered by ACEA E9 and API CK-4 engine qualification sequences.
Corrosion Protection & Bearing Protection
Medium TBN Ca Alkylphenate forms a robust corrosion-inhibiting film on ferrous and non-ferrous metal surfaces. The Ca²⁺ phenate surface film protects camshaft lobes, valve train components, and cylinder liner surfaces from acidic corrosion and corrosive wear. In marine medium-speed diesel engines, the phenate provides particularly good protection for tin-overlay and copper-lead overlay bearings - the phenate's surface-film chemistry is less aggressive to bearing overlays than some ZDDP formulations, and the combination of Ca-phenate + Ca sulfonate is the standard detergent basis for medium-speed marine engine oils meeting MAN/Wärtsilä/Bergen bearing protection requirements.
Applications & Formulation Guidance
1. Heavy-Duty Diesel Engine Oils (HDEO) - Primary Phenate Co-Detergent
Medium TBN Ca Alkylphenate is the standard phenate detergent grade for HDEO additive packages. A typical API CK-4 / ACEA E9 HDEO package might use 2.5–4.0 wt% Medium TBN Ca Alkylphenate (TBN ~150) alongside 2.0–3.0 wt% High TBN Ca Sulfonate (TBN 350) - the phenate contributes ~4.5 mgKOH/g TBN and ~1.5 mgKOH/g effective antioxidant equivalent to the finished oil at typical treat rates, while the sulfonate provides the bulk TBN for long-drain acid neutralisation. The phenate-sulfonate blend enables the HDEO to pass ACEA E9 oxidation (CEC L-101, Mack T-12) and sludge/varnish (Caterpillar C13) tests simultaneously, which would require higher antioxidant loads if sulfonate alone were used as the detergent component.
2. Marine Engine Oils - Trunk Piston & Medium-Speed Diesel
Trunk piston engine oils (TPEO) for medium-speed marine diesels (MAN B&W, Wärtsilä, Caterpillar Marine) typically require finished oil BN of 20–40 mgKOH/g, with the specific BN determined by fuel sulphur content (IMO 2020: VLSFO 0.5%S → BN 25–40; LSMGO/ECA → BN 20–30). Medium TBN Ca Alkylphenate provides a significant fraction of the TPEO's total BN alongside Ca sulfonate, while contributing phenolic antioxidant protection for the long 2,000–4,000 hour oil change intervals typical of marine applications. The phenate-sulfonate combination in TPEO also provides effective bearing and liner protection against the corrosive combustion products of marine diesel fuels.
3. Gas Engine Oils - NOₓ Acid Neutralisation with Antioxidant
Gas engine oils must neutralise nitric acid formed from NOₓ blow-by in lean-burn natural gas and biogas engines, while maintaining exceptional oxidative stability under high-temperature lean-burn conditions. Medium TBN Ca Alkylphenate is well-suited for this dual requirement: its TBN neutralises HNO₃ acid accumulation (pKa 3.3 - stronger than sulphuric acid), while the phenolic antioxidant function retards the nitration-induced oil thickening that is the primary oil degradation mechanism in gas engines. The Ca-phenate's relatively low sulphur contribution (vs. ZDDP-heavy formulations) is also advantageous in gas engines where sulphur-related spark plug fouling and catalyst contamination must be minimised.
4. Gear Oils & Industrial Lubricants - Antioxidant + Mild EP Detergent
In industrial gear oils and high-temperature compressor oils requiring long service stability (6,000–12,000+ hours), Medium TBN Ca Alkylphenate at 0.5–2.5 wt% provides combined detergency, antioxidant supplementation (phenol –OH + disulfide secondary AO), mild EP (–S₂– at asperity contacts), and corrosion inhibition in a single additive. The disulfide EP contribution is particularly relevant in worm gear and moderate-load helical gear applications where the gear oil is expected to contribute mild boundary layer protection at contact pressures below those requiring dedicated extreme pressure additives. The Medium TBN phenate adds meaningful alkalinity reserve (0.6–4.5 mgKOH/g TBN in finished oil at typical treat rates) to buffer acidic oxidation products that accumulate in long-service industrial lubricants.
Additive Compatibility & Blending Notes
| Co-Additive | Compatibility | Formulation Note |
|---|---|---|
| High TBN Ca Sulfonate | ● Industry Standard | The universal HDEO and marine engine oil co-detergent pairing. Ca sulfonate provides the bulk TBN reserve for long-drain acid neutralisation; Ca alkylphenate provides the phenolic antioxidant function and supplementary TBN. Typical HDEO phenate:sulfonate TBN ratio ≈ 25–40:60–75. |
| Low TBN Ca Alkylphenate (same series) | ● Excellent | Blending Low + Medium TBN phenate allows fine TBN calibration within the phenate component without mixing chemical types. Useful when the target finished oil TBN from the phenate fraction falls between the ranges of either grade alone. |
| Primary / Secondary ZDDP | ● Excellent | Triple antioxidant synergy: phenate phenol –OH (primary) + phenate –S₂– (secondary) + ZDDP Zn-dithiophosphate (secondary) covers both radical and hydroperoxide oxidation pathways. Monitor combined S from phenate + ZDDP against finished oil S limit. |
| PIB Bis-Succinimide Dispersant | ● Excellent | Standard HDEO combination. Phenate cleans surfaces (detergency); dispersant suspends soot and oxidation by-products in oil bulk (bulk dispersancy). The two functions are complementary and non-competitive - both are needed in modern high-soot HDEO formulations. |
| Aminic Antioxidant (Alkylated Diphenylamine) | ● Excellent | Aminic AOs complement phenate phenol radical scavenging with peroxy radical trapping at high temperatures - the amine/phenol combination provides superior oxidative stability vs. either alone in long-drain HDEO. The phenate's inherent phenolic AO supplements the aminic AO, potentially allowing a small reduction in the dedicated aminic AO treat rate. |
Frequently Asked Questions
Q: When should a formulator choose Medium TBN Ca Alkylphenate vs the Low TBN grade?
Choose Medium TBN when the formulation needs a substantial TBN contribution from the phenate component - typically when the finished oil target TBN is 12 mgKOH/g or higher and the Ca sulfonate alone cannot provide the required TBN within the ash budget. In HDEO for API CK-4/ACEA E9 (target TBN 12–18 mgKOH/g, S/A ≤1.0%), Medium TBN Ca Alkylphenate at 2.5–4.0 wt% contributes 3.5–7.0 mgKOH/g TBN while using 0.5–0.9 wt% of the available 1.0% S/A budget - an efficient balance. Low TBN grade is preferred when ash is the binding constraint (ACEA C-sequence, S/A ≤0.5–0.8%) and the primary need from the phenate is antioxidant function rather than TBN volume.
Q: What is the significance of the disulfide (–S₂–) vs monosulfide (–S–) structure in C₁₅H₂₃O₂S₂Ca?
The disulfide bridge (–C–S–S–C–) carries two sulphur atoms per bridge compared to monosulfide (–C–S–C–, one sulphur). This matters in two ways: (1) Antioxidant: The –S–S– group is more reactive toward hydroperoxides than –S– alone - disulfide phenates have higher secondary antioxidant activity per molecule. (2) Sulphur content: Disulfide-bridged Ca alkylphenate contributes more sulphur to the finished oil per unit Ca content or TBN than monosulfide grades - formulators targeting the tightest ACEA sulphur limits (S ≤0.3%) may prefer monosulfide-bridged phenate variants. Sinolook can supply both monosulfide and disulfide grades; specify –S– or –S₂– bridging preference or target finished oil sulphur content at order.
Q: Is Medium TBN Ca Alkylphenate suitable for ACEA E9 (low-ash HDEO)?
Yes - Medium TBN Ca Alkylphenate is widely used in ACEA E9 HDEO formulations, but ash budget management is essential. At 3 wt% treat rate of a TBN 150 / Ca 6% grade, the phenate contributes 0.61 wt% S/A to the finished oil - leaving 0.39 wt% S/A for ZDDP antiwear within the ACEA E9 ≤1.0% S/A ceiling. If a higher ZDDP treat rate is needed for antiwear compliance, reduce the phenate to 2.0–2.5 wt% and compensate by switching part of the Ca sulfonate to a higher TBN grade, or by increasing the borated dispersant treat rate (borated dispersants add TBN without contributing S/A). This multi-component TBN optimisation is the core ACEA E9 formulation challenge, and Sinolook's technical team can provide calculation support.
Q: Does Medium TBN Ca Alkylphenate work in both API CK-4 and FA-4 engine oil formulations?
Yes - Medium TBN Ca Alkylphenate is fully compatible with both API CK-4 (SAE 15W-40/10W-30 conventional HDEO) and API FA-4 (SAE 10W-30 fuel-efficient low-viscosity HDEO) formulations. Both specifications require S/A ≤1.0%, and the detergent package (phenate + sulfonate) is essentially the same. The key difference in FA-4 formulation is that the lower finished oil viscosity (SAE 10W-30) increases film thickness sensitivity to additive interactions - verify that the Ca alkylphenate treat rate does not cause cold-crank viscosity (ASTM D5293) issues in the FA-4 viscosity grade. Sinolook can supply a low-viscosity-diluent Medium TBN Ca Alkylphenate variant optimised for FA-4 formulations on request.
Technical & Regulatory References
D2896 (TBN) · D5185 (Ca by ICP-OES) · D2622 (S content) · D874 (sulphated ash) · D92 (flash point) · D445 (viscosity) · D95/KFT (water) · D665 A/B (rust) · D6186 (PDSC oxidation) · D2272 (RBOT) · D130 (copper strip) · D4485 engine performance sequence tests (Mack T-12, Cat C13, Seq VH, Seq IIIGH)
ACEA 2022 E6/E9 (S/A ≤1.0%, heavy-duty low-ash) · API CK-4 / FA-4 (S/A ≤1.0%) · MAN M3575 / M3677 (truck HDEO) · Volvo VDS-5 · Renault RLD-4 · Detroit Fluids Spec 93K222 · Marine: MAN B&W ME/MC series · Wärtsilä W31 / W46 TPEO BN 25–40 · MTU Type 3/4 (gas engine) · Caterpillar ECFIII (gas engine oil)
REACH registered · TSCA inventory listed · No SVHC designation for Ca alkylphenate · Flash point ≥180°C - not classified DG under IMDG/ADR/IATA · EU CLP-classified SDS with disulfide-specific hazard information on request
Low TBN Ca Alkylphenate · High TBN Ca Alkylphenate (next) · High TBN Calcium Sulfonate · Overbased Calcium Sulfonate · Overbased Magnesium Sulfonate · Primary ZDDP · PIB Bis-Succinimide Dispersant · Alkylated Diphenylamine Antioxidant · Nonylated Diphenylamine Antioxidant
Medium TBN Calcium Sulfurized Alkylphenate · TBN 120–180 mgKOH/g · C₁₅H₂₃O₂S₂Ca · COA / TDS / SDS
Request Pricing, TDS & Qualification Sample
Specify target TBN sub-grade (~120 / ~150 / ~180 mgKOH/g or custom), sulfur bridge type (monosulfide –S– or disulfide –S₂–), application (HDEO / marine TPEO / gas engine / gear oil / industrial lubricant), volume, and destination port. Full COA (TBN, Ca%, S%, viscosity, S/A, flash point), TDS, and SDS within 12 hours. Qualification samples (1–5 kg) at nominal charge.
Related: Low TBN Calcium Alkylphenate · High TBN Calcium Alkylphenate · High TBN Calcium Sulfonate · Primary ZDDP · PIB Bis-Succinimide Dispersant
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