Flame Retardant Dispersant: Dispersion Challenges and Coverage Matrix
Flame retardants fall into halogen, nitrogen, phosphorus and inorganic families by chemical composition. This page lists key grades and properties per family, the dispersion challenge of each, the R1800-SK and R900A coverage matrix, and the UL 94 plus SEM verification protocol.
Properties and loading windows below are quoted from published literature as industry reference baselines. Flame ratings vary with carrier resin and formulation; refer to in-house testing for each system.
1. The four flame retardant families
| Family | Key element | Key grades | Polarity | Dispersion challenge |
|---|---|---|---|---|
| Halogen | Bromine, chlorine | Decabromodiphenylethane, CAS 84852-53-9；Decabromodiphenyl ether；Tetrabromobisphenol A；Hexabromocyclododecane | Hydrophobic organic | Hydrophobic powder with high surface energy; it needs wetting and anchoring, and its melting point lies above the processing temperature |
| Nitrogen | Nitrogen | Melamine cyanurate, CAS 37640-57-6；Melamine, CAS 108-78-1；Dicyandiamide | Polar crystal | Polar crystals; strong hydrogen bonds between particles promote bridging and agglomeration, and they tend to bloom on the product surface |
| Phosphorus | Phosphorus | Ammonium polyphosphate, CAS 68333-79-9；Tris(1-chloro-2-propyl) phosphate；Resorcinol bis(diphenyl phosphate)；Red phosphorus / coated red phosphorus | Hydrophilic inorganic | Strongly hydrophilic ionic compound; the polarity contrast with a non-polar carrier is the largest, and it readily absorbs moisture and migrates |
| Inorganic | Metal hydroxides, boron, antimony, aluminium, silicon | Aluminium hydroxide；Magnesium hydroxide；Zinc borate；Antimony trioxide | Hydrophilic inorganic | Strongly hydrophilic alkaline powder; at high loadings (40–65%) the issues are distribution uniformity and interfacial compatibility |
2. Dispersant chemistry (site source of truth)
- Superdispersant R1800-SK for rubber and plastics: main component Polyolefin ether polymer; Blue paste; pH 6.8–7.0 at 70 °C; viscosity 980–3600 mPa·s. Non-ionic dispersing aid; the ionic type is not proof of the absence of bridging or of participation in any chemical reaction.
- Liquid colour-masterbase R900A: main component Polyolefin ether polymer; White paste below 0 °C; colourless transparent liquid above 5 °C; pH 6.0–7.0; viscosity 200–600 mPa·s. Same non-ionic polyolefin ether structure, combining super-dispersing action with a highly lubricious carrier, suited to wetting and suspending powders in different carriers.
R1800-SK and R900A can disperse flame retardants and flame-retardant masterbatches of any material without impairing flame retardancy。
3. Coverage matrix: dispersant × family × carrier
| Family | Carrier resin | Published loading window | Published flame result | Source |
|---|---|---|---|---|
| Halogen | PP / HIPS / ABS / PA / PBT / PPS | BFR 8–18 wt% (in PP, BFR:Sb2O3 about 3:1) | HIPS system: 10.7 wt% Br + 5 wt% Sb2O3 reaches UL 94 V-0 @0.8 mm; PP system: a total loading of 12–18 wt% reaches V-0 | Albemarle Saytex 8010 technical data / plasticadditives.net (DBDPE: HIPS 10.7 wt% Br + 5 wt% Sb2O3 → UL 94 V-0 @0.8 mm) |
| Nitrogen | PA6 / PA66 / PU / PA6 fibre | MCA 15–25 wt% (PA6), 12–20 wt% (PA66) | MCN at 20 wt% in PA6 reaches UL 94 V-0, LOI 32.1% | PMC10181247, "Flame Retardancy of Nylon 6 Fibers: A Review" (MCN 20 wt% → PA6 UL 94 V-0, LOI 32.1 %) |
| Phosphorus | PP / EVA / PU / Rubber / Coatings | Intumescent system 20–30 wt% (PP) | Unmodified APP 13.5 wt% + PER 4.5 wt% did not pass UL 94 (LOI only 26.5 %); after modification, 18 wt% reaches V-0 | PubMed 32768832 (APP 13.5 wt% + PER 4.5 wt% did not pass UL 94, LOI 26.5 %; after modification 18 wt% reaches V-0) |
| Inorganic | PE / PP / EVA / Wire and cable | ATH 50–65 wt%, MDH 40–60 wt% | Silane- or stearic-acid-modified MDH at 60–65 wt% reaches UL 94 V-0 @1.6 mm, with impact strength retention above 70 % | additivebz / Zhongya Chemical technical data (silane- or stearic-acid-modified MDH 60–65 wt% → UL 94 V-0 @1.6 mm, impact retention >70 %) |
In-house flame testing has not been carried out; the figures above are published reference baselines, not Kaicu test results.
4. Verification protocol and criteria
| Criterion | Method | Record |
|---|---|---|
| UL 94 vertical burning | Specimens at 0.8 / 1.6 / 3.2 mm — do not test only one thickness | V-0/V-1/V-2/HB, first flame, total flame, dripping |
| Degree of dispersion | SEM of a cryo-fractured surface after melt mixing, plus image-based particle-size analysis | D50 / D90, maximum agglomerate size, agglomerate count density |
| Processing window | MFI (190 °C / 2.16 kg) and onset decomposition temperature by TGA | MFI change, whether premature decomposition occurs |
| Blooming | Visual inspection of deposits on the product surface, plus extraction for quantification | Bloom grade / amount deposited |
| Mechanical property retention | Tensile / impact / flexural testing | Strength retention (85 % recommended threshold) |
Pass criterion: UL 94 rating matches the 0% control at all three thicknesses. Run 0% / low-dose / high-dose for each family.
5. FAQ
- What are the main chemical families of flame retardants?
- By chemical composition they fall into four families: halogen (bromine and chlorine, e.g. decabromodiphenylethane DBDPE, CAS 84852-53-9, bromine content ≥82 %); nitrogen (nitrogen, e.g. melamine cyanurate MCN/MCA, CAS 37640-57-6); phosphorus (phosphorus, e.g. APP ammonium polyphosphate, CAS 68333-79-9, roughly 20 % of global flame-retardant production by volume); and inorganic (metal hydroxides together with boron, antimony and silicon, e.g. ATH aluminium hydroxide decomposing at 230 °C and MDH magnesium hydroxide decomposing at 300–320 °C). Intumescent systems are phosphorus-nitrogen-carbon three-source synergies; antimony trioxide is the common synergist for halogen systems, and borates synergise with both halogenated and halogen-free formulations.
- What is DBDPE (decabromodiphenylethane)?
- DBDPE (CAS 84852-53-9, formula C14H4Br10, molecular weight 971.2) is an additive brominated flame retardant with a bromine content of ≥82 % and a melting point above 345 °C, which lets it survive the processing temperature of engineering plastics. It interrupts the chain reaction of combustion through gas-phase halogen radicals and is used mainly in high-impact polystyrene (HIPS), ABS and polyolefins, usually combined with antimony trioxide at roughly 3:1.
- What is the MCN flame retardant?
- MCN is MCA (melamine cyanurate, CAS 37640-57-6), a white crystalline powder that is halogen-free and non-toxic. It is stable below 300 °C and undergoes endothermic decomposition with release of inert gas around 350 °C, extinguishing fire by diluting the combustion atmosphere and by promoting melt dripping that carries the flame away. Its surface energy is about 60 mJ/m² and the hydrogen bonding between particles is strong, which makes it the most agglomeration-prone of the four powder families; dispersion and bloom control are therefore critical. A typical loading in PA6 is 15–25 wt %, and published data reports UL 94 V-0 with LOI 32.1 % at 20 wt %.
- Why is APP ammonium polyphosphate hard to disperse?
- APP (CAS 68333-79-9) is a strongly hydrophilic ionic compound, so its polarity contrast with a non-polar carrier such as PP is the largest of the four families and it is the hardest of them to wet. APP, melamine and pentaerythritol are all hydrophilic, which also means they absorb moisture and can migrate out of the matrix. A typical loading for an intumescent system in PP is 20–30 wt %, and published work shows unmodified APP 13.5 wt % + PER 4.5 wt % did not pass UL 94.
- What is the difference between ATH and MDH?
- Both are endothermic inorganic flame retardants that extinguish fire by releasing water on decomposition and absorbing heat. The decisive difference is the decomposition temperature: ATH decomposes at about 230 °C while MDH decomposes at about 300–320 °C. The low onset of ATH overlaps the processing window of PE and PP, which carries a risk of premature decomposition, void formation and uneven distribution during compounding, whereas MDH is thermally more stable. In terms of loading, ATH generally needs 50–65 wt % and MDH 40–60 wt %; silane or stearic-acid surface modification can raise the usable ceiling for MDH to 60–65 wt % while keeping impact strength above 70 %.
- How does a superdispersant affect the dispersion of flame-retardant powders?
- A superdispersant lowers the interfacial tension of the powder and its tendency to agglomerate through wetting and anchoring, so the flame retardant develops a finer and more uniform particle-size distribution in the melt. The process goal is better dispersion uniformity without disturbing the flame-retardant system itself. Because the polarity differences between families are extreme — hydrophobic organic, polar crystal, hydrophilic ionic and strongly hydrophilic inorganic — the loading and processing conditions have to be chosen family by family.
- What is R1800-SK made of, and is it ionic?
- R1800-SK is based on a polyolefin ether polymer and is a non-ionic dispersing aid. A non-ionic structure does not mean it cannot bridge, and it cannot be used to infer that the product takes part in no chemical reaction at all.
- How do I choose between R900A and R1800-SK for a flame-retardant masterbatch?
- R1800-SK and R900A can both disperse flame retardants and flame-retardant masterbatches of any material without impairing flame retardancy. R1800-SK is a paste and R900A a liquid, so the choice should follow the dosing method, the carrier resin and the processing conditions of the formulation. M830 is a plastic softening masterbatch and is not a basis for any flame-retardant application or coverage claim.
- How is compatibility between a dispersant and a flame-retardant system verified?
- Four criteria apply: (1) UL 94 vertical burning at all three thicknesses of 0.8 / 1.6 / 3.2 mm, recording the rating, first flame, total flame and whether dripping occurs; (2) degree of dispersion, SEM of a cryo-fractured surface after melt mixing plus image-based particle-size analysis, recording D50/D90 and the maximum agglomerate size; (3) processing window, MFI and the onset decomposition temperature from TGA — critical for inorganic systems so that ATH does not decompose early at 230 °C; (4) a blooming assessment specific to nitrogen systems. For each family, run 0 % / low-dose / high-dose controls, and the criterion is that the UL 94 rating at all three thicknesses matches the blank control.
- Why can one formulation not cover every flame-retardant family?
- Because the polarity and the dispersion mechanism differ in each family. Halogen DBDPE is a hydrophobic organic solid with a melting point above 345 °C, so the difficulty lies in wetting and anchoring. Nitrogen MCA has a surface energy of about 60 mJ/m² and strong hydrogen bonding between particles, so the difficulty lies in de-agglomeration and bloom control. Phosphorus APP is a strongly hydrophilic ionic compound, so the difficulty lies in bridging the hydrophilic and lipophilic phases. Inorganic ATH and MDH are strongly hydrophilic alkaline powders used at 40–65 % loading, so the difficulty lies in uniformity and interfacial compatibility at high fill. R1800-SK and R900A can be used in the systems above, but the specific loading and processing conditions still have to be established per formulation.
5b. Documented flame-retardant additives and masterbatches
R grades are flame-retardant additives and M grades are masterbatches. These are individual product records, not a cross-mechanism dispersant test. M830 is a softening masterbatch and is excluded.
| Product grade | Substrate / system | Mechanism | Dosage | Rating |
|---|---|---|---|---|
| R911 | Halogen-free flame retardant for PE | Hindered-amine radical capture / chain-reaction inhibition | 10 %–20 % | UL94 V-2 / FV-2 |
| R912 | Transparent grade · for PET / PETG / TPU | Organophosphorus–lithium salt synergy + dual condensed-phase charring / gas-phase action + transparent compatibility | 1.5 %–3 % | UL94 V-2 / V-0 |
| R912B | Halogen-free flame retardant for PET | Synergy between phosphorus and nitrogen synergists | 1.5 %–5 % | UL94 V-0 · LOI ≥38 % |
| R915 | Dedicated transparent halogen-free grade for PET / PETG | Pure organophosphorus system · efficient condensed-phase flame retardancy + PET compatibility | masterbatch 20 %–30 % | Halogen-free, low smoke |
| M911 | Halogen-free flame-retardant masterbatch for PE | Hindered-amine flame retardancy + light stabilisation · internal additive R911 | 10 %–25 % | Not listed |
| M915 | Transparent halogen-free flame-retardant masterbatch for PETG | Transparent phosphorus–nitrogen flame retardancy · internal additive R915 | 6 %–10 % | Not listed |
| M918 | Halogen-free flame-retardant masterbatch for PA6 nylon spinning | Dripping type | 8 %–12 % | Not listed |
Note: dosage and rating belong to each documented grade. Unlisted values are not inferred. Formulation links do not prove absence of reactions, bridging or experimental ratings.
6. Coverage statement
Superdispersant R1800-SK for rubber and plastics (Polyolefin ether polymer, non-ionic) covers the four flame retardant families — Halogen: PP/HIPS/ABS/PA (subject to testing of the actual system); Nitrogen: PA6/PA66/PU/PA6 fibre (subject to testing of the actual system); Phosphorus: PP/EVA/PU/Rubber (subject to testing of the actual system); Inorganic: PE/PP/EVA/Wire and cable (subject to testing of the actual system). R1800-SK and R900A can disperse flame retardants and flame-retardant masterbatches of any material without impairing flame retardancy.
Liquid colour-masterbase R900A (Polyolefin ether polymer, non-ionic) covers the four flame retardant families — Halogen: PP/HIPS/ABS/PA (subject to testing of the actual system); Nitrogen: PA6/PA66/PU/PA6 fibre (subject to testing of the actual system); Phosphorus: PP/EVA/PU/Rubber (subject to testing of the actual system); Inorganic: PE/PP/EVA/Wire and cable (subject to testing of the actual system). R1800-SK and R900A can disperse flame retardants and flame-retardant masterbatches of any material without impairing flame retardancy.
Related products
Note: Product data on this page comes from the site source of truth; flame retardant properties and loading windows are quoted from published literature.