| HS Code | 807566 |
| Product Name | 3D/6D/8D/15D Flame retardant polyester staple fibers |
| Material Composition | 100% polyester (PET) |
| Denier | 3D, 6D, 8D, 15D |
| Fiber Type | Staple fiber |
| Flame Retardant Type | Phosphorus-based flame retardant |
| Limiting Oxygen Index | ≥28% |
| Tenacity | 2.5-4.5 cN/dtex |
| Elongation At Break | 20-50% |
| Cut Length | 32-102 mm, customizable |
| Crimp | 8-15 crimps per 25 mm |
| Moisture Regain | ≤0.6% |
| Melting Point | 255-265 °C |
| Density | 1.38-1.40 g/cm³ |
| Color | Raw white, black, or dyed |
| Cross Section | Round or hollow |
| Thermal Shrinkage | ≤5% at 180 °C |
| Flammability | Self-extinguishing |
| Chemical Resistance | Good acid resistance; limited alkali resistance |
As an accredited 3D/6D/8D/15D Flame retardant polyester staple fibers factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Flame retardant polyester staple fibers packed in 250 kg compressed bales, wrapped in woven polypropylene bags, strapped for bulk transport. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL): 3D/6D/8D/15D flame retardant polyester staple fibers loaded palletized, moisture-protected, evenly distributed, and secured for ocean transport. |
| Shipping | Flame retardant polyester staple fibers (3D/6D/8D/15D) are non-hazardous. Ship in PP woven bales or cartons, palletized and shrink-wrapped. Use clean, dry containers via sea, land, or rail. Store in a dry, ventilated area, away from open flames. Avoid moisture, hooks, and prolonged direct sunlight. No special dangerous goods handling required. |
| Storage | Store in a cool, dry, well-ventilated warehouse, away from direct sunlight, rain, moisture, and heat. Keep original packaging sealed and palletized off the floor. Separate from acids, alkalis, oxidizers, and ignition sources. Avoid static electricity and friction. Maintain humidity control and provide firefighting equipment. Do not smoke. Keep clean. Inspect regularly. Under recommended conditions, shelf life is typically 12–24 months. |
| Shelf Life | Shelf life: 12–24 months for 3D/6D/8D/15D flame retardant polyester staple fibers stored cool, dry, ventilated, in unopened original packaging. |
Flame-retardant polyester staple fibre in 3D, 6D, 8D, and 15D counts is produced by melt spinning a phosphorus-containing ethylene terephthalate copolymer, followed by drawing, crimping, heat-setting, and cutting to staple lengths between 32 mm and 102 mm. Denier is the linear mass per 9,000 m of filament; 3D yields compact, uniform nonwoven webs and 15D yields high void volume and compression recovery. The downstream applications in which this material is consumed at scale are limited to automotive interior nonwovens, upholstered seating and mattress fire barriers, architectural acoustic/thermal panels, and medium-temperature dry filtration media. The sector-specific requirements differ in fire standard, fibre blend ratio, conversion equipment, and finished article family, and are therefore treated separately below.
| Fibre denier | Typical cut length | Primary conversion route | Representative area mass | Reference standard |
|---|---|---|---|---|
| 3D | 32–51 mm | Carding, needlepunch, thermal bonding | 120–350 g/m² | FMVSS 302 / ISO 3795 |
| 6D | 51–64 mm | Airlay, high-loft batting, thermal bonding | 200–600 g/m² | TB 117-2013 / EN 1021 |
| 8D | 51–76 mm | Airlay, compression moulding, acoustic panel bonding | 300–900 g/m² | EN 13501-1 / ASTM E84 |
| 15D | 64–102 mm | Coarse needlefelt, calender bonding, heat-setting | 300–700 g/m² | ISO 11057 / ASTM D2863 |
Automotive interior nonwoven components are qualified on the finished composite, not on loose fibre, because the scrim, adhesive film, or face fabric changes the burn path. Horizontal burning behaviour is controlled under 49 CFR § 571.302, ISO 3795:1989, UNECE Regulation No. 118, and SAE J369; the ISO method applies a 100 mm/min burn-rate threshold and FMVSS 302 applies 102 mm/min for interior materials. In a headliner substrate at 180–250 g/m², the furnish comprises 60–70 wt% 3D FR PET and 30–40 wt% 6D FR PET, with the 6D fraction preventing web drafting defects and preserving loft after thermoforming. Trunk floor cover and wheel arch liner constructions at 150–250 g/m² use 100% 3D FR PET where low fibre dusting and uniform surface filling are required. The fibre is opened, carded, cross-lapped, and needlepunched on a 2.5 m production line; worker/stripper settings are held between 0.25 mm and 0.40 mm, and doffer speed is reduced from 160 m/min to 120 m/min when running 3D fibre to maintain web weight CV below 3.0%. Needlepunched at 350–500 p/cm² using 40–42 gauge needles, the web reaches sufficient entanglement for thermoforming; below 250 p/cm² the material delaminates under preform drape, and above 600 p/cm² fibre breakage raises dusting without improving tensile strength. Optional thermal bonding with 5–10 wt% low-melt bicomponent PET at 140–150 °C is used for semi-rigid panels. Finished component types include headliner face and back substrates, parcel shelf panels, trunk floor covers, wheel arch liners, and A/B/C pillar trim bases. Continuous service above 130 °C is not recommended because polyester hydrolysis embrittlement accelerates when relative humidity exceeds 80%.
In upholstered seating, the 6D and 8D FR PET staple fibre is converted into high-loft barrier batting inserted between the cover fabric and flexible polyurethane foam. Smoldering and small-open-flame compliance is established under California Technical Bulletin 117-2013, EN 1021-1:2014, EN 1021-2:2014, BS 5852, and 16 CFR Part 1640, which references ASTM E1353 for U.S. federal upholstered furniture smolder testing. In a mill-scale barrier batt of 200–300 g/m², the 6D/8D FR PET addition ratio is 30–45 wt%, with the balance 55–70 wt% comprising FR cellulosic or modacrylic fibre. Above 50 wt% FR PET, the batt stiffens and the char becomes melt-rich under match-flame exposure, which reduces the barrier's ability to hold a coherent char layer. The production route is an airlay high-loft line of 1.5–2.5 m width running at 40–80 m/min; when thermal bonding is specified, 10–15 wt% low-melt bicomponent fibre is included and the web is bonded in a through-air oven at 145–165 °C for 2–4 min. Finished component forms are seat cushion wraps, backrest inserts, arm pad barriers, and continuous batt rolls for contract furniture, office seating, and cinema seating.
When a mattress panel is built for 16 CFR Part 1633 open-flame verification, the 6D FR PET component functions as a char-stabilizing fibre within a cellulosic or modacrylic matrix rather than as the sole barrier. The applicable U.S. test methods are 16 CFR Part 1632 for cigarette ignition and 16 CFR Part 1633 for open-flame heat release, with acceptance limits of 200 kW peak heat release and 15 MJ total heat release in the first 10 min; European mattress programmes may be qualified under EN 597-1:2015, EN 597-2:2015, and BS 7177. In a representative 250–400 g/m² barrier batt, the 6D FR PET addition ratio is limited to 15–30 wt%, with FR cellulosic or modacrylic fibre at 70–85 wt%. This loading retains char cohesion and prevents tear-out along needle lines; above 35 wt%, molten polymer accumulation during cone calorimeter exposure can create localized char discontinuities. The conversion route is carding or airlay followed by through-air bonding at 150–160 °C; 8D and 15D are generally not specified for low-area-weight mattress barrier carding because batt uniformity deteriorates. Quilting fibre and topper batting may be 100% 6D FR PET, but they are not substitutes for the tested barrier layer. Finished components include mattress panel barriers, border wall liners, quilt-back fire liners, and crib-mattress sleeves where the full assembly is tested. Published data for 8D and 15D fibre in this specific barrier configuration is limited.
Architectural acoustic and thermal insulation panels made from FR PET staple fibre are classified for reaction to fire under EN 13501-1:2018; North American surface burning characteristics are tested by ASTM E84, where Class A requires flame spread index below 25 and smoke developed index below 450. The Chinese domestic market classification is GB 8624-2012, and small-flame ignitability is screened by ISO 11925-2:2020. The fibre is not an inherently non-combustible product; many FR PET acoustic panels achieve B-s1,d0 only with controlled density, thickness, and facing configuration, so the test certificate must state the exact panel assembly rather than the fibre alone.
The panel core is made by airlaying 60–75 wt% 8D FR PET, 0–15 wt% 6D FR PET, and 25–40 wt% low-melt bicomponent PET. Wall and ceiling absorbers at 20–35 kg/m³ rely on 8D fibre for compression recovery; semi-rigid floor and partition panels at 40–60 kg/m³ may include 15D fibre up to 20 wt%. Above this level, panel tensile strength falls below 0.15 MPa and edge chipping during CNC routing becomes unacceptable. The web passes through a through-air oven with a 145 °C / 160 °C / 150 °C profile, and a hydraulic platen applies 5–10 kN/m² to set thickness and compression set. On CNC machining lines, tungsten carbide tooling is used; feed rates are reduced for high-15D variants because tool dwell above 80 °C induces surface melting and chipping. Finished component types include wall acoustic panels, ceiling baffles, HVAC duct liner panels, office partition infill, and door core sound insulation.
Dry filtration media for medium-temperature baghouses and cartridge filters is produced from 15D and 6D FR PET staple fibre where continuous service temperature does not exceed 130 °C. Flammability screening of the fibre is performed by limiting oxygen index per ASTM D2863; FR PET grades specified for filtration typically show 27–32% oxygen. Cleanability and dust release of the needlefelt are evaluated under ISO 11057:2011, and system-level combustibility is assessed under the applicable combustible dust standard such as NFPA 652. In a 300–700 g/m² needlefelt, the back layer uses 50–70 wt% 15D FR PET and the face layer uses 70–100 wt% 6D FR PET; the 15D phase supplies the coarse pore skeleton and the 6D phase controls surface filtration and dust release.
On production needlepunch lines, the crosslapped batt is needled at 500–800 p/cm² with 40 gauge barbed needles, then calendered at 180–200 °C and heat-set at 210–220 °C for 2–3 min. When the 15D fraction exceeds 60 wt%, line speed is reduced by 20–30% because the coarser fibre increases card cylinder load and shortens card clothing life. Needling density above 800 p/cm² reduces air permeability below the target window for many baghouse applications, while density below 400 p/cm² permits delamination under pulse-jet cleaning. Finished product families include baghouse filter bags, pleated cartridge media, panel filter sheets, and dryer filter cloths for non-aggressive, medium-temperature gas streams. Published data for the specific combination of calendered FR PET and 15D fibre in pleated cartridge media is limited; pilot trials with the final pleating geometry are required before production-scale runs are committed.
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Flame-retardant polyester staple fibre is produced by incorporating a phosphorus-containing comonomer into the polyethylene terephthalate backbone during continuous polycondensation rather than by applying a topical finish after fibre forming. The product is available in 3D, 6D, 8D, and 15D designations, corresponding to nominal linear densities of 3.3 dtex, 6.7 dtex, 8.9 dtex, and 16.7 dtex. Model codes combine linear density and cut length: FRPET-3D/51 mm identifies a 3 denier staple cut to 51 mm. Standard cut lengths include 32 mm, 38 mm, 51 mm, 64 mm, 76 mm, and 102 mm. The phosphorus-modified polymer raises the limiting oxygen index of a 200 g/m² needlepunched web to 30–34% under ASTM D2863, compared with 20–22% for conventional polyethylene terephthalate staple. The flame-retardant function is polymer-bound and does not rely on a water-soluble ammonium polyphosphate coating, which is a principal difference from low-cost post-treated polyester staple.
Routine quality inspection covers linear density by ISO 1973, tenacity and elongation at break by ISO 5079, and crimp number by ASTM D3937. The values in Table 1 are production averages, not specification limits; lot acceptance should be based on batch certificates.
Typical physical property envelope for the four linear densities:
| Designation | Nominal linear density | Typical cut length | Tenacity | Elongation at break | Crimp number |
|---|---|---|---|---|---|
| 3D | 3.3 dtex | 32–51 mm | 4.0–4.5 cN/dtex | 25–35% | 12–16 per 25 mm |
| 6D | 6.7 dtex | 51–64 mm | 3.8–4.3 cN/dtex | 28–38% | 11–15 per 25 mm |
| 8D | 8.9 dtex | 64–76 mm | 3.6–4.0 cN/dtex | 30–40% | 10–14 per 25 mm |
| 15D | 16.7 dtex | 76–102 mm | 3.4–3.8 cN/dtex | 35–45% | 9–13 per 25 mm |
During fibre spinning, the phosphorus-modified resin is dried at 160–175 °C for 4 h to a moisture content below 30 ppm before extrusion at 285–295 °C. Spin finish is applied at 0.10–0.20% by mass. Unlike standard polyester staple, the phosphorus comonomer narrows the melt-spinning window; barrel temperature deviations exceeding ±3 °C can increase die-face drip and oligomer deposition on production spinnerets.
Fibre decitex governs the number of fibres per unit mass, web coverage, and needlepunch densification. A 3D/51 mm staple contains approximately 5.9 × 10⁴ fibres per gram, while a 15D/102 mm staple contains approximately 5.9 × 10³ fibres per gram. On a 1.2 m wide high-speed card running at 60 m/min doffer output, 3D/51 mm is sensitive to static accumulation below 45% RH; electrostatically driven neps and cylinder-wrapping rise sharply. Conditioning at 55–65% RH and 22–25 °C with an antistatic spin finish at 0.15–0.20% by mass is required for stable carding. In contrast, 15D/102 mm staple cards with lower fibre-to-metal friction and less cylinder load, but web uniformity at basis weights below 150 g/m² deteriorates because of the lower fibre count per gram.
Needlepunch parameters shift with linear density. 3D and 6D staple are commonly punched with 15 × 18 × 36 × 3.5 RB needles at penetration densities of 60–100 punches/cm². For 15D high-loft batts, treatment is typically reduced to 30–50 punches/cm² to limit needle deflection and retain bulk. A 15D/300 g/m² batt shows higher compression recovery than a 6D/300 g/m² batt, but the surface is more open and may require lamination or a denser scrim for flame test reproducibility.
Before thermal bonding or lamination, predrying is executed when fibre moisture exceeds 0.6%. The staple is dried in a through-air dryer at 120 °C for 4 h at an air velocity of 1.5 m/s; residual moisture above 0.4% creates steam-blown voids in thermobonded webs. Processing temperature must not exceed 170 °C in continuous ovens because the phosphorus comonomer accelerates thermo-oxidative discoloration above this threshold. The fibre is incompatible with alkaline padding baths above pH 9 at temperatures above 80 °C, which can hydrolyse the polyester backbone and reduce tenacity by more than 10% after 60 min exposure.
Flammability classification is construction-dependent. A 200 g/m² needlepunched felt made from 6D/64 mm staple can be evaluated under NFPA 701 and FMVSS 302; typical results show afterflame below 2.0 s and no flaming drip under horizontal mounting. For vertical burner tests under FAR 25.853, a 400 g/m² high-density felt can achieve a char length below the regulatory threshold. A 15D/200 g/m² airlaid web with high void volume may exhibit faster surface flame spread and is not automatically acceptable because the fibre itself meets a specified limiting oxygen index. Test reports should therefore be based on the final fabric construction rather than fibre-level LOI alone. Published comparative data for 15D/200 g/m² airlaid webs under FAR 25.853 is limited; pre-qualification burn testing on production-equivalent fabric is mandatory.
Compared with regular polyester staple, the phosphorus-modified grade forms a carbonaceous char and suppresses melt-dripping. Flame-retardant treated cotton using tetrakis(hydroxymethyl)phosphonium salts passes vertical flame tests but can lose efficacy after repeated alkaline laundering. The phosphorus comonomer in the polyester chain withstands 50 domestic washing cycles at 60 °C under ISO 6330 with less than 5% loss in LOI. Modacrylic fibre has a soft hand and high LOI of approximately 28–33%, but it releases acidic vapours during thermal processing and has lower thermal stability. The phosphorus-modified polyester can be processed on standard polyester needlepunch lines if dryer temperatures are maintained below 170 °C.
The low moisture regain of 0.4% under ASTM D2654 reduces drying time in filled bedding but increases static-charge generation during garnetting; antistatic finishes are required when relative humidity falls below 50%. Cotton, with moisture regain of 8–13%, absorbs water and loses loft when wet. Modacrylic, with moisture regain of 3–4%, is closer in hand but cannot be exposed to repeated high-temperature dryer cycles above 140 °C without dimensional stability loss. The 15D/102 mm polyester fill retains loft after autoclaving at 134 °C for 20 min, which is relevant for hospital bed materials requiring thermal disinfection. Published comparative data for the specific combination of 15D/102 mm flame-retardant polyester in a 300 g/m² airlaid fill under ISO 12952-2 mattress ignition tests is limited; component-level testing is required for each final construction. Avoid combining this fibre with amine-based additives or melamine-containing intumescent finishes because amine-phosphorus interactions can cause premature char formation and discoloration during thermobonding at 150–170 °C.
Storage should be maintained at 20–25 °C and 55–65% RH in closed bale wrapping. If bales are opened more than 72 h before processing, reconditioning is required. The product should not be blended with chlorinated fibres such as modacrylic in thermally bonded nonwovens because hydrogen chloride generated at 160 °C degrades the phosphorus-containing polyester. Compliance does not rest solely on fibre-level LOI; every final fabric or composite must be qualified under the relevant fire test standard for the target market, including NFPA 701, FMVSS 302, FAR 25.853, or EN 45545-2 where applicable.
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