Lubricant Additives - Ashless Dispersants Series: Boron-Phosphated PIB Bis-Succinimide is the most functionally complex dispersant in the Sinolook series - the only grade simultaneously containing N + B + P active elements in a single molecule. The bis-succinimide backbone provides shear-stable dual-PIB dispersancy; boron contributes TBN and antioxidant activity (as in Borated Bis-Succinimide); and the added phosphate ester group (–O–P(=O)(OH)–O–) provides a uniquely strong phosphate-glass anti-wear tribofilm mechanism that exceeds the soft BN-type film of borated grades. Critical formulation note: the structural phosphorus (P 0.2–0.7%) is measurable by ASTM D4047 and must be included in the phosphorus budget of ACEA C-specification and API SP formulations. This grade is optimally used in HDEO, severe-duty, and industrial applications where P limits are less restrictive. Sinolook supplies: PIBSI · Bis · Poly · Borated PIBSI · Borated Bis · Boron-Phosphated Bis-Succinimide · Low Viscosity Dispersant.
Lubricant Additive · Triple-Functional N+B+P Dispersant · Phosphate Ester Anti-Wear · Boron AO+TBN · Dual-PIB Shear-Stable · HDEO Severe-Duty · Industrial · ⚠ P budget required in ACEA C-specs
Boron-Phosphated PIB Bis-Succinimide
Boron Phosphated Polyisobutylene Bis-Succinimide / N 1.5–3.0 wt% · B 0.3–1.0 wt% · P 0.2–0.7 wt% / Highest Anti-Wear Performance in Dispersant Series · Severe-Duty HDEO · EGR · Industrial
| Chemical Class | Boron-phosphated polyisobutylene bis-succinimide - produced by bis-succinimide synthesis (two PIBSA units + polyamine) followed by sequential or simultaneous boronation and phosphation; phosphorus is introduced as a phosphate ester linkage (–O–P(=O)(OH)–O–) grafted onto the succinic acid residue hydroxyl or amine groups; boron forms cyclic or linear borate ester coordination with remaining polar groups; the final molecule contains three distinct active element centres: imide nitrogen (N), borate ester boron (B), and phosphate ester phosphorus (P) - all covalently bound in the polymer architecture; mineral oil diluent; NO Ca/Mg/Zn/Ba / structural sulphur absent |
| Structure (image) | N–CH–C(=O)–[PIB]–C(=O)–O–P(=O)(OH)–O– with adjacent boron (B, green); three-element active cluster visible in 3D model: green = B, orange = P (unique dual-element active centre), blue = N, red = O (phosphate + borate oxygens), grey/white = C/H; the co-localisation of B and P in the polar head group creates an unusually dense multi-element active centre for adsorption onto metal surfaces and soot particles simultaneously |
| ★ Unique Identifier | ★ Only N+B+P triple-element dispersant in Sinolook series Phosphate ester → FePO₄ tribofilm - strongest AW of series ⚠ P 0.2–0.7% by D4047 - must count in SAPS P budget |
| SAPS Status | S/A: ~0 (ASTM D874 - no metal ash) S: ~0 wt% (no structural sulphur) ⚠ P: 0.2–0.7 wt% - COUNTS in ACEA/API P limit |
| GHS Hazards | Combustible liquid FP ≥180°C H315/H319 skin/eye irritant |
What Is Boron-Phosphated PIB Bis-Succinimide?
Boron-Phosphated PIB Bis-Succinimide is the most functionally complex member of the Sinolook ashless dispersant series - the only grade that simultaneously incorporates three distinct active element centres (N, B, P) within a single bis-succinimide polymer molecule. The synthesis builds upon the borated bis-succinimide platform (PIB Bis-Succinimide + controlled boronation, as described for the previous grade) and adds a further phosphation step: a phosphorus source (typically phosphoric acid, H₃PO₄, or a phosphate ester precursor) reacts with the remaining free hydroxyl or amino groups on the succinimide–polyamine backbone under controlled temperature and vacuum, forming covalent phosphate ester linkages (–O–P(=O)(OH)–O–) that graft phosphorus atoms directly into the polar head group architecture alongside the boron centres.
The strategic importance of adding phosphorus to an already-borated bis-succinimide is the qualitative upgrade it provides to the anti-wear mechanism. While boron alone generates a soft amorphous BN-type boundary film at the tribological contact zone (adequate for moderate load applications), phosphorus generates a fundamentally different and stronger protective mechanism: phosphate glass tribofilm. Under tribological stress at the metal contact interface, the phosphate ester groups in the dispersant undergo tribochemical transformation to iron(III) phosphate (FePO₄) or mixed iron boron phosphate glassy layers - the same class of hard, low-friction, chemically inert glassy film that provides ZDDP's celebrated anti-wear performance, but generated here from an ashless, sulphur-free, metal-free phosphate ester source. The result is a step-change improvement in anti-wear film strength that fundamentally distinguishes this grade from all other succinimide dispersants in the series.
| Grade | N% | B% | P% | AW Film Type | P in SAPS budget? |
|---|---|---|---|---|---|
| PIBSI (mono) | 0.8–2.5 | 0 | 0 | None | No P contribution |
| Bis-Succinimide | 1.5–3.5 | 0 | 0 | None | No P contribution |
| Poly-Succinimide | 2.0–6.0 | 0 | 0 | None | No P contribution |
| Borated PIBSI | 1.5–2.5 | 0.5–1.5 | 0 | Soft BN film | No P contribution |
| Borated Bis | 1.5–3.0 | 0.3–1.0 | 0 | Cyclic BN film | No P contribution |
| B-P Bis ★ (this grade) | 1.5–3.0 | 0.3–1.0 | ★ 0.2–0.7 | ★ FePO₄ + BN glass (strongest) | ⚠ YES - 0.2–0.7% by D4047 |
P budget note: The 0.2–0.7% structural phosphorus is the defining formulation constraint for this grade. It simultaneously provides the series' strongest anti-wear tribofilm but requires careful SAPS accounting. ACEA E6/E9 (HDEO) has no P limit - freely usable. ACEA C3 limits P ≤0.08% in finished oil - a 5 wt% treat of a 0.5% P grade contributes 5×0.005 = 0.025% P to finished oil (well within C3 limit). At higher treat rates or higher-P grade variants, verify the P contribution from the dispersant is included in total P accounting alongside ZDDP and other P-containing additives.
Critical Formulation Note: Phosphorus Counts in SAPS Budget
Boron-Phosphated PIB Bis-Succinimide is the only dispersant in the Sinolook series that contributes measurable phosphorus to the finished oil formulation. The structural phosphate ester groups are covalently bonded to the molecule and will be measured as phosphorus by ASTM D4047 (ICP-OES). This phosphorus contribution must be included in the total phosphorus budget when formulating to specifications that limit phosphorus in finished oil.
| Specification | P limit (finished oil) | P contribution from 5 wt% treat (0.5% P grade) | Assessment |
|---|---|---|---|
| ACEA C1 | ≤ 0.05% | +0.025% | Half P limit consumed by dispersant alone - use low-P grade (0.2%) or reduce treat; ZDDP budget severely constrained; not recommended |
| ACEA C2/C3 | ≤ 0.08% | +0.025% | 31% of P limit used - leaves 0.055% for ZDDP (adequate for most ZDDP treat rates); manageable if using low-P grade (0.2–0.3%) and/or ≤5 wt% treat |
| API SP / ILSAC GF-6 | ≤ 0.08% | +0.025% | Same as ACEA C3; use low-P grade variant; include dispersant P in total P accounting with ZDDP |
| ACEA E6/E9 (HDEO) | No P limit | +0.025% | ★ No constraint - freely usable at any grade variant and treat rate; optimal application for this dispersant |
| API CK-4 / Industrial | No P limit | +0.025% | ★ No constraint - preferred application |
Best practice: Always specify the target P% grade at order (0.2–0.7%), and calculate the total P contribution from dispersant + ZDDP + any other P-containing additives before confirming compliance with the finished oil specification. Sinolook provides multiple P% grades - a lower-P variant (0.2–0.3%) offers the tribofilm anti-wear benefit with minimum P budget impact.
Technical Specification
Borated grades (BN-type boundary film):
Boron centre adsorbs onto ferrous metal surface oxide sites via Lewis acid–base interaction; under tribological stress forms an amorphous boron-containing layer (B₂O₃/BN-type) of 2–5 nm thickness; properties: soft (low shear strength = low friction), conformable, easily replenishable from the oil phase, most effective at low contact pressures and low sliding speeds (cold-start, boundary lubrication onset); Hertz contact pressures: effective at 0.5–1.5 GPa. Wear scar diameter in 4-ball wear test (ASTM D4172): typically reduces WSD by 10–20% vs non-borated grade.
★ Boron-Phosphated grade (FePO₄ glass tribofilm):
Phosphate ester groups undergo tribochemical reaction with iron surface at contact temperatures (200–300°C in asperity contact zones); reaction: R–O–PO₃H₂ + Fe₂O₃ → FePO₄ glass + R–OH + H₂O; the resulting iron phosphate glassy film (same mechanism as ZDDP secondary anti-wear, but metal-free) is 20–50 nm thick, has high hardness (7–8 GPa by nanoindentation), low shear strength due to glassy structure, and extremely low thermal conductivity (heat-insulating → reduces thermal wear); effective at 0.5–3.0 GPa Hertz pressure. WSD reduction in 4-ball: 30–50% vs non-borated grade - significantly stronger than BN-film alone. The combined BN + FePO₄ dual-layer present in this grade provides synergistic coverage: BN for low-P onset, FePO₄ for high-load severe-duty protection.
| Parameter | Specification | Test Method | Note |
|---|---|---|---|
| Appearance | Brown to dark brown viscous liquid | Visual | Darker than borated bis alone due to additional P=O polarity groups; warm to 40–60°C for handling and blending |
| Nitrogen Content | 1.5–3.0 wt% | ASTM D5291/D3228 | Dispersancy metric; grade-specific on COA; slightly lower than non-borated bis because more –NH groups converted to B/P ester bonds during modification |
| Boron Content | 0.3–1.0 wt% | ICP-OES | TBN ~8–25 mgKOH/g contribution + AO + partial BN boundary film; grade-specific on COA |
| Phosphorus Content ★ ⚠ | 0.2–0.7 wt% | ASTM D4047 | UNIQUE to this grade - MUST include in P budget for ACEA C1/C2/C3/C5 and API SP formulations; see SAPS table above; specify target P% at order; provides FePO₄ anti-wear glass tribofilm |
| Flash Point (COC) | ≥ 180–200°C | ASTM D92 | Grade-dependent; confirm on COA/TDS for specific P% variant ordered |
| Kinematic Viscosity @100°C | 200–450 cSt | ASTM D445 | Include in SAE viscosity calculation; highest in borated sub-series; warm to 50–70°C before blending for highest-P grades; use gear pump |
| Density @20°C | 0.95–1.05 g/cm³ | ASTM D4052 | Use for mass-to-volume treat rate conversion in volumetric blending; elevated vs non-borated grades |
| Sulphated Ash / Sulphur | ~0 / ~0 wt% | ASTM D874 / D2622 | No Ca/Mg/Zn metals - S/A ~0; no structural sulphur. Only P is the relevant SAPS parameter. |
| Packaging | 180 kg drum · 900–1000 L IBC · Flexitank | - | Store 0–45°C; sealed (phosphate ester + borate ester both moisture-sensitive - maintain sealed); 24-month shelf life; KFT ≤0.15% on receipt |
Performance Profile - Five Simultaneous Functions
① Soot/Sludge Dispersancy (Bis Backbone)
The bis-succinimide backbone provides dual-PIB steric stabilisation of soot particles in the bulk oil phase - same mechanism as non-borated bis-succinimide. Dispersancy performance confirmed by ASTM D7843 blotter spot test and Sequence VH sludge rating. The N% (1.5–3.0%) maintains adequate polar adsorption site density for soot encapsulation despite partial conversion of –NH groups to B and P ester linkages. In extreme soot-loading conditions (Mack T-13 test, soot >4 wt%), the dual-PIB bis architecture provides superior viscosity control vs mono-succinimide grades.
② Shear Stability (Dual-PIB Anchor)
Two PIB tails flanking the polar head group provide the same shear stability mechanism as non-borated bis-succinimide and borated bis-succinimide - both PIB chains must be simultaneously cleaved to reduce molecular functionality under shear. In CEC L-45 and ASTM D6278 shear stability testing, boron-phosphated bis-succinimide shows equivalent or marginally better shear stability vs borated bis-succinimide alone - the phosphate ester groups add further steric bulk to the polar head, slightly reducing chain mobility and susceptibility to mechanical shear alignment. Suitable for ATF, CVT, and severe-duty HDEO applications where shear stability is a key formulation requirement.
③ Boron AO + TBN (B–O–N centres)
The boron centres (0.3–1.0%) provide TBN 8–25 mgKOH/g and B–O–N radical chain termination antioxidant activity - same mechanisms as Borated Bis-Succinimide. The TBN contribution is slightly lower than pure Borated Bis-Succinimide (TBN 10–30 mgKOH/g) because some B coordination sites are occupied by adjacent phosphate ester oxygen atoms (competitive coordination between B and P for the available polar groups), marginally reducing the B–N Lewis acid-base TBN contribution. The AO mechanism (B–O–N radical termination) is fully retained and provides synergistic antioxidant activity alongside the phosphate ester's own oxidation-inhibiting effect (P=O groups can also interrupt radical chain reactions through polar quenching).
④ ★ FePO₄ Tribofilm Anti-Wear (Strongest in Series)
This is the defining performance advantage of the boron-phosphated grade. Under boundary lubrication conditions, the phosphate ester groups (–O–P(=O)(OH)–O–) adsorb onto iron oxide surface sites and undergo tribochemical transformation at asperity contact temperatures (200–300°C local contact temperature): the organic phosphate ester cleaves thermally/mechanically, generating inorganic iron(III) phosphate (FePO₄) glass that fills and smooths surface asperities. This 20–50 nm hard glassy film is: (a) harder than the BN-type film from borated grades alone (nanoindentation hardness 7–8 GPa vs 2–4 GPa for BN); (b) self-regenerating from the dispersant remaining in the oil phase; (c) metal-free and sulphur-free (unlike ZDDP glass); (d) more thermally stable than ZDDP tribofilm at temperatures >200°C. 4-ball WSD reduction: 30–50% below non-borated baseline - the strongest anti-wear effect of any grade in the dispersant series.
⑤ ZDDP Synergy - P Budget Redistribution Strategy
In formulations where the total phosphorus budget is binding (ACEA C3: P ≤0.08%), the boron-phosphated dispersant can enable a strategic ZDDP P budget redistribution: the dispersant's phosphate ester tribofilm provides anti-wear coverage at low speed/high load (boundary lubrication, cold-start) while ZDDP provides anti-wear at mixed and EHL regimes. In certain HDEO formulations, replacing 0.3% ZDDP treat with boron-phosphated dispersant at equivalent P contribution maintains total anti-wear performance (validated in ASTM Sequence IVA and CEC L-51) while simultaneously gaining the dispersant's soot/sludge control function - a net formulation simplification and cost saving. This P-redistribution strategy requires specific engine test validation before commercial adoption, as the tribological regime coverage of phosphate ester dispersant vs ZDDP is different and must be verified for the target specification.
Applications & Formulation Guidance
1. Severe-Duty HDEO - Maximum Anti-Wear at Zero S/A, Zero S
ACEA E6/E9 and API CK-4 HDEO formulations have no phosphorus limit - making this the optimal application for boron-phosphated bis-succinimide at full P% grade (0.5–0.7%) and full treat rate (5–8 wt%). The combination of high-soot bis-succinimide dispersancy, sustained boron AO throughout the long drain, and the strongest phosphate-glass anti-wear tribofilm of any dispersant grade provides a complete performance package for 100,000+ km severe-duty HDEO service. Particularly advantageous in EGR-heavy diesel engines where both high soot loading and elevated tribological stress (high valve train and piston ring contact pressures from cylinder pressure spikes) are simultaneously present.
2. PCMO Low-SAPS - Low-P Grade Variant with ZDDP P Budget Optimisation
For ACEA C3 and API SP PCMO formulations where P ≤0.08%, the low-P grade variant (P 0.2–0.3%) at 4–5 wt% treat contributes only 0.008–0.015% P to finished oil - leaving 0.065–0.072% P available for ZDDP. This enables the formulator to capture the full five-function performance of the boron-phosphated dispersant (including FePO₄ tribofilm anti-wear supplementation) while respecting the phosphorus limit. The trade-off vs Borated Bis-Succinimide is a slightly tighter P budget that requires careful accounting, offset by the superior anti-wear film strength of the phosphate tribofilm. Recommended only where the formulator specifically needs the P-based anti-wear function and has confirmed budget headroom for the dispersant's P contribution.
3. Industrial Severe-Duty & Marine - Maximum Protection in Harsh Service
In industrial gear oils (ISO VG 220–680 CLP), reciprocating compressor oils (4,000+ hours), and marine TPEO where no P limits apply, boron-phosphated bis-succinimide provides the highest total protection level in the dispersant series: deposit control + boron AO for extended oxidative stability + phosphate glass tribofilm for gear flank and bearing protection under extreme load (>2 GPa Hertz contact pressures in hypoid/worm gears). The phosphate ester tribofilm's high thermal stability (stable at temperatures >250°C) is particularly advantageous in compressor oils and high-temperature circulating systems where ZDDP tribofilm can degrade and lose effectiveness above 180°C.
4. Multi-Grade Fleet & Gas Engine Oils - AW/AO/Dispersancy in One Additive
In cost-sensitive fleet lubricant formulations (SAE 15W-40, 20W-50) where the additive package count must be minimised for economics, the boron-phosphated bis-succinimide's five-in-one functionality (dispersancy + shear stability + TBN + AO + anti-wear) allows formulators to consolidate what would otherwise require three separate additives (dispersant + AO + anti-wear supplement) into a single component. For gas engine oils with 1,500–2,000 hour drain intervals, the combination of sustained boron AO (NOₓ radical termination) and phosphate glass tribofilm (valve stem and cam wear protection) addresses the two primary failure modes of gas engine lubricant performance - oxidative degradation and valve train wear - simultaneously from one ashless, sulphur-free additive.
Frequently Asked Questions
Q: Does "phosphorus-modified ashless dispersant" mean this grade is no longer SAPS-free?
The term "ashless" refers specifically to the absence of metal-derived sulphated ash (ASTM D874) - which this grade retains, as there are no Ca, Mg, Zn, Ba, or other metallic elements. However, "SAPS" in modern lubricant specifications stands for "Sulphated Ash, Phosphorus, and Sulphur" - three separate parameters, each independently limited. This grade has: S/A ≈ 0 (ashless) ✓; S ≈ 0 (sulphur-free) ✓; but P = 0.2–0.7 wt% (phosphorus-containing) ✗ vs the other series grades. So it is correctly described as "ashless and sulphur-free but phosphorus-containing" - meeting two of the three SAPS requirements at zero, but introducing a non-zero P contribution that must be accounted for in the phosphorus-limited specifications (ACEA C1/C2/C3/C5, API SP, ILSAC GF-6). In specifications without P limits (ACEA E6/E9, API CK-4, most industrial specs), this distinction is irrelevant.
Q: How does the phosphate ester tribofilm in this dispersant compare to ZDDP anti-wear?
Both ZDDP and the phosphate ester in this dispersant generate glassy phosphate tribofilms at metal contact surfaces under tribological stress - but through different mechanisms and with different film characteristics. ZDDP generates a zinc polyphosphate glass film via thermally activated (100–150°C bulk oil temperature) decomposition; it is highly effective across a wide tribological regime range, particularly in mixed and EHL conditions. The dispersant's phosphate ester generates an iron(III) phosphate (FePO₄) film via tribochemically activated (200–300°C contact temperature) reaction with iron oxide surface - it is most effective in boundary lubrication (very high contact pressure, low speed). Practically: ZDDP is the primary anti-wear additive and cannot be replaced by phosphate ester dispersant alone; the phosphate ester dispersant provides supplemental anti-wear coverage at boundary lubrication onset conditions (cold-start, high load, low speed) that precede the full ZDDP tribofilm formation temperature. The two mechanisms are complementary and synergistic - their combination in 4-ball wear testing gives additive or synergistic WSD reduction beyond either alone.
Q: Is the phosphate ester linkage in this grade sensitive to hydrolysis, and how does its moisture stability compare to the borate ester?
Phosphate esters (P–O–C bonds) are generally more hydrolytically stable than borate esters (B–O–C bonds) under the same conditions - phosphorus forms stronger P–O–C bonds (bond dissociation energy ~360 kJ/mol) compared to the B–O–C bond (~335 kJ/mol), and the P=O group is a poorer Lewis acid than the boron centre, making it less susceptible to nucleophilic attack by water molecules. In practice: (1) The phosphate ester in this grade does not require the same strict moisture exclusion as the borated grades - standard sealed storage (≤0.15% water by KFT) is sufficient; (2) In the finished oil at typical crankcase temperatures, phosphate ester hydrolysis is negligible over a 15,000 km drain interval; (3) The borate ester groups in the same molecule are more moisture-sensitive than the phosphate ester groups - the KFT ≤0.15% water limit applies primarily to protect the borate ester component. Grade-specific moisture sensitivity data is available on the SDS and TDS provided with each shipment.
Technical & Regulatory References
D5291/D3228 (N%) · ICP-OES (B%) · ASTM D4047 (P% - critical for SAPS budget) · D4052 (density) · D445 (viscosity 200–450 cSt) · D92 (FP ≥180–200°C) · D874 (S/A ~0) · D2622 (S ~0) · KFT (H₂O ≤0.15%) · D7843 (blotter soot) · ASTM D4172 (4-ball wear - 30–50% WSD reduction vs baseline) · CEC L-45/D6278 (shear stability) · Mack T-12/T-13 · ASTM Sequence IVA (cam wear) · ASTM Sequence IIIGH (oxidation)
★ Optimal: ACEA E6/E9 · API CK-4/FA-4 (no P limit) · Industrial gear DIN 51517 CLP · ISO 6743 · Marine TPEO · API CK-4 off-highway. With P budget: ACEA C2/C3 (low-P grade ≤0.3%) · API SP/ILSAC GF-6 (low-P grade). Not recommended: ACEA C1/C5 (P ≤0.05% - too constrained unless low-P grade <0.2%)
REACH registered · TSCA listed · No SVHC · S/A ~0 (D874) · S ~0 · P 0.2–0.7% by D4047 - must declare in finished oil P calculation · DPF/GPF compatible (phosphorus does not block DPF catalyst sites at dispersant treat concentrations; verify grade-specific) · GHS SDS available
PIBSI · Bis-Succinimide · Poly-Succinimide · Borated PIBSI · Borated PIB Bis-Succinimide · Boron-Phosphated PIB Bis-Succinimide ✅ · Low Viscosity Dispersant (next - final in series)
Boron-Phosphated PIB Bis-Succinimide · N 1.5–3.0% · B 0.3–1.0% · P 0.2–0.7% · FePO₄+BN Tribofilm · Zero S/A · Zero S · ⚠ P budget required · COA/TDS/SDS
Request Pricing, TDS & Qualification Sample
Specify target N%, B%, and P% grade (0.2–0.7 wt%; specify low-P for ACEA C2/C3, full-P for HDEO/industrial), application, volume, and destination port. Full COA including P% by ASTM D4047, TDS, and SDS within 12 hours. Qualification samples (1–5 kg) available.
Ashless Dispersants: PIBSI ✅ · Bis ✅ · Poly ✅ · Borated PIBSI ✅ · Borated Bis ✅ · Boron-Phosphated Bis ✅ · Low Viscosity Dispersant (next - final)
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