| HS Code | 516112 |
| Product Name | Kuraray VINARL T-18 1.7T Flame-Retardant PVA Fiber |
| Manufacturer | Kuraray Co., Ltd. |
| Fiber Material | Polyvinyl Alcohol (PVA) |
| Product Grade | T-18 |
| Fiber Form | Staple (cut) fiber |
| Linear Density | 1.7 tex |
| Equivalent Filament Diameter | approximately 40 µm |
| Specific Gravity | 1.30 |
| Moisture Regain | approximately 4.0% |
| Tensile Strength | approximately 1.6 GPa |
| Elongation At Break | approximately 6-7% |
| Young S Modulus | approximately 40 GPa |
| Initial Modulus | approximately 350 cN/dtex |
| Limiting Oxygen Index Loi | approximately 32 vol% |
| Chemical Resistance | resistant to common acids, alkalies, and organic solvents |
As an accredited Kuraray VINARL T-18 1.7T-Flame-Retardant PVA Fiber factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Kuraray VINARL T-18 1.7T-Flame-Retardant PVA Fiber is packed in 25 kg moisture-proof woven bags, with 40 bags per pallet. |
| Container Loading (20′ FCL) | 20′ FCL: flame-retardant PVA fiber loaded in palletized, moisture-protected bales, secured for safe transport. Approximately 20 words. |
| Shipping | Kuraray VINARL T-18 is shipped as flame-retardant PVA fiber in sealed, moisture-proof bales or cartons. Transport via clean, dry containers, protected from direct moisture and mechanical damage. Handle with standard precautions; non-hazardous under normal shipping conditions. Store in a cool, well-ventilated area away from ignition sources. Ensure proper labeling during transit. |
| Storage | Store Kuraray VINARL T-18 FR PVA fiber in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and open flames. Keep packaging tightly sealed to prevent moisture absorption and contamination. Do not store with oxidizing agents or incompatible chemicals. Follow standard industrial hygiene practices; handle gently to avoid dust generation. |
| Shelf Life | Shelf life is indefinite when stored in a cool, dry, well-ventilated area away from direct sunlight and moisture. |
In flame-resistant mid-layer assemblies for arc-rated worker clothing, 1.7 dtex FR PVA fibre is blended with para-aramid and flame-retardant viscose at 15–35 wt% to control afterflame time and char length. The fibre is selected for its non-melting behaviour and its ability to form a coherent carbonaceous residue under convective flame impingement. Flame-retardant PVA fibre grades are reported to exhibit limiting oxygen index values in the range of 28–32% under ISO 4589-2:2017. Blend homogeneity is maintained by a two-pass carding operation using a semi-worsted card with worker-stripper ratios set between 0.8 and 1.2. The needle-punched batt is produced at a mass per unit area of 150–300 g/m². Needle density is typically 400–800 punches/cm². Aramid-rich outer layers carry mechanical load, while the FR PVA-containing inner web provides char integrity and moisture management. The nonwoven is heat set at 120–140 °C for 45–90 s to reduce residual shrinkage to below 2% when tested according to ISO 5077:2007. Flame performance is verified under ASTM D6413/D6413M-22 with afterflame time ≤2.0 s and char length ≤100 mm for defined multilayer configurations. Garments are certified to EN ISO 11612:2015 for heat and flame protection, with supplementary arc rating determined by IEC 61482-1-1:2019 or ASTM F1959/F1959M-22. The operational boundary is set by the fibre’s moisture regain of approximately 5–7% at 65% RH, which requires humidity-controlled storage before carding to avoid fibre wrapping on worker rollers. The FR PVA layer is not used as a standalone outer shell for welding splash or molten metal exposure. It is always positioned behind a thermally stable aramid or FR cotton shell fabric. Published data for this specific blend configuration in arc-rated garments is limited, so mill trials generally verify char length on a three-layer assembly rather than relying on single-fibre test values.
Acid dew point corrosion in off-gas filtration is a more frequent failure mode than dry heat ageing. FR PVA fibre is incorporated into meta-aramid needled felts at 10–25 wt% for off-gas streams in non-ferrous smelters where operating temperature does not exceed 140 °C continuously. The fibre contributes acid resistance in dilute sulfuric acid mist and retains dimensional stability after heat setting at 130–150 °C. Carding is conducted on a nonwoven line with a fibre blend of 1.7 dtex FR PVA, 2.2 dtex meta-aramid, and optional 1.7 dtex polyimide when short surge excursions to 160 °C are specified. The batt is cross-lapped to 500–650 g/m² and needled with 40-gauge felting needles at 700–900 punches/cm². Singeing and calendering are performed at 130–150 °C to reduce surface fibre and improve membrane bonding if an ePTFE laminate is applied. Dimensional stability is tested by ISO 9073-2:1995 tensile strength and by hot-air exposure at 150 °C for 90 min, with accepted area shrinkage below 2%. Flammability of the filter medium is assessed using DIN 53438-2:1984 for limited flame spread. The operational boundary is clear. Continuous exposure above 140 °C in the presence of oxidising gases causes progressive tensile loss due to chain scission of the polyvinyl alcohol backbone. Filter bags in coal-fired boilers, cement kilns, or incinerators with sustained inlet temperatures above 180 °C are outside the application window for this fibre. Strong hot nitric acid and hypochlorite environments are also avoided because they accelerate oxidative degradation. Published data for Kuraray VINARL T-18 1.7T in hot sulfuric acid aerosol environments is limited. Laboratory screening typically uses immersion in 10% H2SO4 at 80 °C for 24 h followed by tensile retention against ISO 13934-1:2013.
Short-cut 1.7 dtex FR PVA fibre is metered into dry-mix friction formulations at 1.5–5.0 wt%. The fibre is cut to 3 mm or 6 mm in length. It is added after abrasive and filler components in a horizontal ploughshare mixer or an Eirich intensive mixer to prevent fibre breakage. Mixing is conducted at 30–80 °C for 6–12 min. The fibre improves green strength of pre-forms and reduces edge cracking. It chars rather than melts during high-temperature friction events. Pre-forming is executed at 18–25 MPa in a cold pre-form press. Hot pressing is performed at 155–175 °C under 15–30 MPa for 6–10 min. Post-cure is run at 170–190 °C for 4–6 h. The hot press cycle is constrained by the thermal stability of the fibre. Press temperatures above 190 °C or dwell times beyond 12 min produce thermo-oxidative degradation of the polyvinyl alcohol chain, visible as darkening and a drop in shear strength. Moisture content of the bulk mix must be below 1.0% before hot pressing. Steam loss during pressing causes blistering and delamination at the friction material-backing plate interface. Friction performance is tested on a Chase machine according to SAE J661:2021 and on a scale dynamometer to ISO 26867:2009. Vehicle-level conformity is verified under ECE R90 where replacement brake pads are regulated.
| Formulation ID | FR PVA fibre wt% | Pre-form pressure MPa | Hot press temperature °C | Post-cure time h |
|---|---|---|---|---|
| F1 | 1.5–2.5 | 18–20 | 155–160 | 4 |
| F2 | 2.5–3.5 | 20–22 | 160–165 | 5 |
| F3 | 3.5–5.0 | 22–25 | 165–175 | 6 |
Batch-to-batch variance in fibre length distribution is monitored after dry mixing by image analysis. A coefficient of variation below 15% in retained fibre length is required to maintain consistent pre-form green strength. Aggressive mixing above 120 °C or extended blending beyond 15 min is avoided because mechanical shear and thermal load act synergistically to fibrillate and shorten the fibre. The end product is a friction composite with reduced catastrophic fade at the pad-disc interface and improved low-temperature green strength compared with non-fibre control compounds.
Because the vulcanizate requires dimensional stability during continuous flexing, 6 mm chopped FR PVA fibre is incorporated into NBR/CR conveyor belt covers at 3–8 phr. Fibre addition is made on a two-roll mill with a friction ratio of 1:1.15–1:1.25 and a roll temperature of 40–60 °C. The FR PVA fibre is added after black and plasticizer dispersion to orient the fibre in the rolling direction. The resulting compound shows a Mooney viscosity increase of 5–20 MU at ML 1+4, 100 °C. Vulcanization is carried out at 150–170 °C in a compression or continuous press. Cure time is adjusted to t90 determined by moving die rheometry per ISO 6502:2016. The fibre does not melt or drip when the cured rubber is exposed to flame. This supports flame-resistant conveyor belt cover compounds tested under ISO 340:2013 for surface flame propagation. Mechanical validation includes tensile strength to ISO 37:2017, tear strength to ISO 34-1:2015, and abrasion resistance to ISO 4649:2017. Hot-air ageing is performed at 100 °C for 168 h according to ISO 188:2011. Because the fibre has high moisture regain, predrying at 80 °C for 2 h is specified when ambient storage RH exceeds 60%. Moisture above 0.5% in the compound produces porosity at the vulcanizate surface. Process temperature above 180 °C is avoided because the polyvinyl alcohol fibre undergoes thermal degradation. The end product is a flame-retardant conveyor belt cover with improved tear strength and reduced edge tearing during splicing. Published data for this specific grade in CR-based covers is limited. Mill trials typically compare tear retention after ageing rather than single-point values.
Finely fibrillated FR PVA fibre is applied in wet-laid nonwovens at 5–20 wt%. Fibre length for papermaking is controlled at 2–6 mm. The stock is prepared at 0.5–1.0% consistency in a hydrapulper. pH is maintained at 6–8. Dispersion is assisted by polyethylene oxide or polyacrylamide at 0.02–0.05% based on dry fibre mass. The furnish may contain 20–40 wt% aluminium trihydroxide or magnesium dihydroxide for smoke suppression and flame retardancy. Formation is carried out on a cylinder mould or inclined wire former. Wet pressing reduces water content before drying in multi-cylinder dryers at 110–130 °C. Calendering is performed at 80–120 °C with a nip load of 50–150 kN/m to densify the sheet. Flame retardancy is assessed by UL 94 V-0 at thickness 0.8 mm. Smoke density is tested according to ASTM D5132-19. Electrical insulation board is classified under IEC 60641-3-1:2008 for low-voltage applications. Packaging applications are pre-qualified by NFPA 701:2019 for flame propagation. The operational boundary is moisture sensitivity. After conditioning at 23 °C and 50% RH, the sheet reaches equilibrium moisture that reduces dielectric strength compared with dry condition. The material is not specified for oil-filled power transformer insulation operating continuously above 105 °C. Published data for Kuraray VINARL T-18 1.7T in electrical insulation paper is limited. Qualification requires batch-to-batch verification of dispersion uniformity and flame spread after humidity conditioning.
Air-laid nonwoven facings for acoustic ceiling panels incorporate 5–10 wt% FR PVA fibre as partial replacement for glass scrim. The fibre supplies flame retardancy without generating sharp fibre dust during slitting. The furnish consists of 20–40 wt% glass fibre, 40–60 wt% cellulosic fibre, and a binder applied by spray or foam. Binder solids are set at 10–18% of dry web mass. Through-air drying is conducted at 100–120 °C. Embossing is performed at 120–140 °C to bond the facing to the acoustic substrate. Fire classification is verified under EN 13501-1:2018 for reaction to fire. Surface flame spread is classified under ASTM E84-23a, with Class A or Class 1 requirements for wall and ceiling materials. Heat release rate is tested by cone calorimetry to ISO 5660-1:2015 at 50 kW/m². The FR PVA web contributes char integrity and reduces the need for halogenated binders. The operational boundary is exterior exposure. The facing is not suitable for direct outdoor installation without a protective laminate because cycling humidity above 80% RH causes dimensional change. The forming line requires humidity control below 65% RH to maintain fibre opening and fibre-binder distribution. Published data for this specific ceiling tile configuration is limited. Product development is based on cone calorimeter total heat release and visual char cohesion after test.
Competitive Kuraray VINARL T-18 1.7T-Flame-Retardant PVA Fiber prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615380400285 or mail to sales2@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615380400285
Email: sales2@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Kuraray VINARL T-18 1.7T-Flame-Retardant PVA Fiber is a polyvinyl alcohol staple fibre grade engineered for applications that combine tensile load transfer, aqueous dispersion, alkali resistance, and flame retardancy. The designation is interpreted as a nominal linear density of 1.7 dtex and a cut length of 18 mm; tolerance limits and test report values require a grade-specific certificate of analysis from Kuraray. The fibre incorporates a halogen-free flame-retardant system that raises the limiting oxygen index relative to unmodified PVA fibre when measured under ISO 4589-2:2017. The product is positioned for carded nonwoven barriers, cementitious reinforcement, wet-laid papers, and halogen-free thermoplastic compounding where fibre melting drip and brominated FR chemistry are undesirable.
The 1.7 dtex filament provides a specific surface area that supports dispersion in water-based and dry-mix processes, while the 18 mm cut length is intended for carded nonwoven, wet-laid, and short-fibre compounding rather than continuous filament winding. The fibre density is typically 1.30 g/cm³ for PVA grades; tensile strength and elongation at break should be verified against the certificate of analysis using ISO 2062:2009 or JIS L 1015:2010. Published data for this specific flame-retardant configuration is limited. Representative flame-retardant PVA staple fibre of this titre shows tenacity in the range 8–12 cN/dtex and elongation at break from 7–12% after conditioning at 20°C and 65% RH. Moisture regain of 5–8% is common for PVA fibre; this is higher than polyester fibre and lower than viscose fibre.
In carded nonwoven barrier fabrics for contract upholstery and mattress panels, the T-18 1.7T staple is opened on standard fine-opening lines and carded on a nonwoven line with a working width of 1.5 m at line speeds between 30 m/min and 60 m/min. The crimp and cut length allow web formation without excessive nep generation, but pre-drying is recommended if the fibre has been stored at relative humidity above 60% because PVA fibre absorbs moisture and can affect card clothing loading and web uniformity. The nonwoven fabric is tested for limited flame spread under EN ISO 15025:2016 and for heat release under ISO 5660-1:2015 when used in barrier applications. In this context, the T-18 1.7T grade is selected over flame-retardant polyester because its char is more cohesive and because it does not melt-drip in the same manner as thermoplastic polyester fibre.
The principal difference is the halogen-free flame-retardant additive package, which raises the limiting oxygen index from approximately 19–20% for unmodified PVA fibre to a representative range of 28–32% under ISO 4589-2:2017. Unlike meta-aramid, which retains mechanical integrity above 400°C but is hydrophobic and difficult to disperse in aqueous slurry, the PVA fibre retains hydroxyl functionality and wetting characteristics. Compared with flame-retardant viscose, the T-18 1.7T grade has higher wet strength retention as a fibre class, although published wet strength retention data for this exact grade is limited. Table 1 provides comparative property ranges from public industrial fibre-class data.
Table 1. Comparative property ranges for flame-retardant PVA fibre and adjacent fibre classes.
| Property | Standard PVA fibre | T-18 1.7T FR PVA representative range | FR polyester | Meta-aramid |
|---|---|---|---|---|
| Nominal titre | 1.0–2.2 dtex | 1.7 dtex | 1.7–3.3 dtex | 1.7–2.2 dtex |
| Density | 1.30 g/cm³ | 1.30 g/cm³ | 1.38 g/cm³ | 1.38 g/cm³ |
| Tenacity | 10–17 cN/dtex | 8–12 cN/dtex | 2.5–4.5 cN/dtex | 3.5–5.5 cN/dtex |
| Limiting oxygen index | 19–20% | 28–32% | 28–32% | 28–30% |
| Moisture regain | 5–8% | 5–8% | 0.4% | 4.5–5.5% |
| Thermal behaviour | decomposes around 200–230°C | decomposes around 200–230°C; char former | melts around 255°C | decomposes above 400°C |
Values are representative ranges from public fibre-class sources, not grade-specific certificate of analysis data for Kuraray VINARL T-18 1.7T-Flame-Retardant PVA Fiber.
At a water-to-cement ratio of 0.35, the fibre is added at 0.6–1.5 kg/m³ in extruded or Hatschek sheet cement board to control plastic shrinkage cracking and improve post-crack toughness. The alkali resistance of PVA fibre is relevant because the pore solution in ordinary Portland cement reaches pH 12.5–13.5. Fibre dispersion is monitored by wash-out tests on a 63 µm sieve; clumping is a processing failure mode on industrial lines when addition exceeds 2.0 kg/m³ without prior water prewetting. The char-forming flame-retardant system does not significantly affect cement hydration at addition rates below 1.5% by mass of cement, but dosages above this threshold may require adjustment of the superplasticizer demand due to fibre surface adsorption.
In halogen-free flame-retardant polypropylene and thermoplastic vulcanizate compounds, the T-18 1.7T staple is side-stuffed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 to 44:1 at a melt temperature not exceeding 200°C. The temperature limit is not set by the base polymer but by the onset of PVA decomposition, which begins below the secondary melting transition and is characterized by weight loss detectable by thermogravimetric analysis under nitrogen at 10 K/min. Processing above 210°C can generate acetaldehyde and discoloration; therefore, the grade is not recommended for polyamide or polycarbonate compounding unless the residence time is kept under 60 s and the melt temperature is separately validated. The hydroxyl surface improves interfacial adhesion in polar matrices, but the fibre is incompatible with amine-based processing stabilizers that accelerate PVA degradation.
The fine filament geometry increases char conversion rate by reducing the diffusion path for oxygen and heat. Under cone calorimetry at 35 kW/m² incident heat flux according to ISO 5660-1:2015, thin PVA fibre webs of this titre tend to form a continuous intumescent char layer, but the char is hygroscopic and loses dimensional stability above 85% RH. Producers should avoid storing flame-retardant PVA fibre in unsealed polyethylene liners in coastal or high-humidity warehouses. The residual char of the flame-retardant grade is more cohesive than standard PVA char, but the specific char strength is not currently covered by a single ISO test method; published data for this exact configuration is limited. Thermogravimetric analysis under air at 10 K/min typically shows a major mass-loss onset between 200°C and 230°C for PVA fibre; the flame-retardant additive may shift the char yield at 600°C upward compared with unmodified fibre.
Following wet-laid sheet formation on an inclined-wire fourdrinier with a fibre retention aid dosage of 0.1–0.3% active polymer on dry fibre, the hydrated PVA fibre forms a conformable sheet for electrical insulation paper and filter media. Because the fibre does not melt at processing temperatures, it remains dimensionally stable in through-air drying at 120–140°C, but over-drying above 60 min at 150°C can embrittle the flame-retardant additive package. In wet-laid processing, the T-18 1.7T cut length is at the upper limit for uniform dispersion; longer fibres are avoided because of flocculation in the forming section.
Under REACH Regulation (EC) No 1907/2006 and RoHS Directive 2011/65/EU as amended by (EU) 2015/863, the fibre is evaluated as an article. No SVHC is expected above 0.1% w/w based on the typical composition of Kuraray halogen-free PVA fibre, but the end-user must review the safety data sheet for the specific production lot. The fibre is not intended for food-contact use unless a specific compliance statement is issued. Table 2 summarizes the standard framework for flame-retardant textile and nonwoven applications.
Table 2. Compliance and test method matrix for flame-retardant applications.
| Application | Standard | Measured parameter |
|---|---|---|
| Limited flame spread in protective clothing | EN ISO 15025:2016 | Flame spread time, afterflame, afterglow |
| Oxygen index of fibre web | ISO 4589-2:2017 | Minimum oxygen concentration required to sustain combustion |
| Heat release rate in barrier materials | ISO 5660-1:2015 | Peak heat release rate, total heat release |
| Smoke density | ISO 5659-2:2018 | Specific optical density under controlled pyrolysis |
| Automotive interior flammability | FMVSS 302 | Horizontal burn rate |
In protective clothing laminates for welding and electrical arc exposure, the fibre is blended with para-aramid and flame-retardant viscose at a mass fraction of 20–40% to balance comfort and thermal stability. The PVA component contributes moisture regain and softness, which reduces the stiffness associated with aramid-rich fabrics. Arc rating is determined under IEC 61482-2:2018 or ASTM F1959/F1959M-22; the T-18 1.7T grade is used as the char-forming component, but arc thermal performance depends on the full fabric construction and outer shell material. The operational limit is colouration and tensile loss under repeated industrial laundering; PVA fibre can lose tensile strength after 25 cycles under ISO 15797:2018, though published data for this specific grade is limited.
