| HS Code | 589521 |
| Material | Polyvinyl alcohol (PVA) synthetic fiber |
| Form | Chopped short-cut structural fiber intended for papermaking/wet-laid nonwoven reinforcement |
| Density | 1.30 g/cm³ |
| Standard Cut Length | 3 mm (also available as 6 mm type depending on grade) |
| Fiber Diameter | Approximately 13 µm |
| Linear Density Fineness | Approximately 1.1 dtex |
| Tensile Strength | Approximately 1.0 GPa |
| Initial Modulus | Approximately 30 GPa |
| Elongation At Break | Approximately 6%–8% |
| Hot Water Resistance | Insoluble and dimensionally stable in boiling water |
| Melting Softening Point | Around 230°C, with decomposition/thermal degradation occurring above this temperature |
As an accredited Kuraray VPB103-PVA Structural Fiber for Paper Making factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Kuraray VPB103-PVA structural fiber for paper making is packaged in 20 kg woven polypropylene bags with polyethylene liners, palletized and wrapped. |
| Container Loading (20′ FCL) | Load 20′ FCL with palletized PVA fiber bales, ensuring dry, ventilated stowage and secure lashing to prevent shift during transit. |
| Shipping | Kuraray VPB103-PVA structural fiber ships in dry, sealed bales or cartons to prevent moisture absorption. It is non-hazardous, suitable for standard freight, and should be stored in a cool, dry area away from direct sunlight and humidity. Handle gently to avoid fiber breakage and contamination during transport. |
| Storage | Store in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep in the original, tightly sealed container to prevent moisture absorption and contamination. Avoid humid conditions, as PVA fibers are hygroscopic. Maintain moderate temperatures and separate from oxidizing agents or incompatible chemicals until ready for use. |
| Shelf Life | Shelf life is typically 24 months when stored dry, in original sealed packaging, away from moisture and direct sunlight. |
Within recycled corrugating medium and linerboard production, the structural contribution of VPB103 is evaluated through ring crush and edge crush performance under ISO 3037 and short-span compressive strength under ISO 9895. The furnish most often consists of a blend of old corrugated containers at 70–90 wt% of total bone-dry fibre, mixed office waste, and softwood kraft reinforcement fibre. VPB103 addition at 2.5–6.0 wt% of bone-dry furnish is directed at compensating dry-end strength losses associated with hornification of repeatedly reslushed recycled fibre and with reduced fibre length distribution after deflaking. The fibre is added after the low-consistency refining stage, either by dry metering into the machine chest or by pre-slushing in a separate low-shear pulper operated below 20°C to prevent cluster formation; addition before disc refiners is not recommended because the high shear shortens the PVA fibre and reduces its structural contribution. The downstream process route is a multi-ply fourdrinier or gap former operating at headbox solids of 0.8–1.2%, with VPB103 retention supported by a cationized starch or polyacrylamide retention system. Synthetic fibre retention below 75% has been observed if the fibre is introduced after the fan pump or if the approach-flow system does not generate sufficient turbulence to overcome rope formation. Terminal product types are ECT-rated corrugating medium and linerboard for inner pack and agricultural bulk transport packaging subjected to high humidity or repeated vertical stacking. Compliance for non-food packaging starts with REACH Regulation (EC) No 1907/2006 including Annex XVII restrictions; if the finished containerboard grade is intended for direct contact with dry foodstuffs, converters usually require a supplier declaration under FDA 21 CFR 176.170 and EU Regulation 1935/2004. Reel specifications most often controlled are ring crush strength per ISO 3037, edge crush strength per ISO 3037, short-span compressive strength per ISO 9895, and Cobb water absorptiveness per ISO 535. VPB103 addition within the indicated range does not replace PAE wet-strength resin in fully water-resistant packaging.
The use of VPB103 in wet-lay filtration media addresses the need for a synthetic reinforcing fibre that can be processed on conventional fourdrinier or inclined-wire machines without the brittleness of glass fibre and with sheet formation indices comparable to long-cut polyester fibre in air-permeable grades. The downstream segment is split between engine oil filter media, industrial intake air media, and cabin air filter base paper; each imposes a different combination of pore structure, stiffness, and pleat retention. Addition ratio in filtration furnish normally ranges from 3.0 wt% to 10.0 wt% of total fibre mass, with the lower bound controlled by measurable tensile improvement and the upper bound constrained by furnish cost and drainage. VPB103 is dispersed with softwood kraft or unbeaten mercerized pulp; pre-slushing is carried out at 1.5–2.5% consistency with a short dwell time to prevent fibre flexing before blending. Production for resin-bonded oil filter grades proceeds from wet-lay formation at grammages between 90 g/m² and 180 g/m², followed by water-based or solvent-based phenolic resin saturation on a size press, infrared or through-air drying, and subsequent pleating on rotary pleaters; bending stiffness after resin cure is measured by Taber bending stiffness per ISO 2493-1. Compliance standards are application-specific: engine oil filter media must pass ISO 4548-12 for full-flow oil filters; industrial intake air media is tested according to ISO 5011; HVAC panel media may be classified to ISO 16890-1 for particle filtration efficiency. Terminal product types are cartridge oil filter elements for heavy-duty diesel engines, radial seal intake air panels, and pleated cabin air filter inserts. A process conflict arises from the thermoplastic character of PVA fibre: calendar temperatures above the softening point of the fibre may create localized bonding and collapse the pore structure, so surface calendering is typically replaced with a soft-nip calender or omitted for grades requiring a specific air permeability above 180 L/m²/s at 200 Pa.
For heat-sealable tea bag and single-serve infusion papers, the role of VPB103 is not primarily dry-state tensile reinforcement but the creation of a more uniform, low-porosity sheet with improved fibre bonding at the wire side and reduced inter-fibre void when calendered under controlled moisture. Improved bonding is measured as wet tensile after water immersion at 23°C per ISO 3781; reduced inter-fibre void is measured as air permeance per ISO 5636-3. This application is governed by direct food-contact legislation; a VPB103 grade intended for food-contact paper must be accompanied by a declaration that it conforms to FDA 21 CFR 176.170 components of paper and paperboard in contact with aqueous and fatty foods, EU Framework Regulation 1935/2004, and, for the German market, BfR Recommendation XXXVI for paper and board intended for food contact. The addition ratio in infusion tissue is generally 2.0–5.0 wt% of fibrillated softwood and abaca furnish; higher levels can reduce the seal strength of heat-sealable bicomponent fibre when the paper is sealed on double-heated jaw sealers. On an inclined wire or yankee fourdrinier machine running at grammages of 12–24 g/m², stock preparation requires separate slushing of VPB103 in cold water to prevent premature swelling, low-shear transfer, and addition at the machine chest after refining of abaca. Wet-end retention is monitored because free PVA fines may migrate to the felt and cause build-up on the yankee dryer. Terminal product types are non-heat-seal and heat-seal tea bag paper, herb infusion sachets, and coffee pod filter lidding. Producers commonly specify dry tensile strength per ISO 1924-2, wet tensile strength per ISO 3781, and air permeance per ISO 5636-3. A limitation is that VPB103 does not confer grease resistance; grades requiring an oil barrier still require a fluorochemical or acrylic dispersion treatment, and the interaction between that coating and the swollen PVA fibre at the drying stage must be validated because published data for this specific configuration is limited.
Moulded fibre protective packaging for consumer electronics and white goods transport differs from flat paper grades because the furnish is vacuum-formed on three-dimensional wire tools rather than dried as a continuous web. VPB103 is added at 1.5–4.0 wt% of the moulded pulp furnish, typically a mixture of old newsprint, kraft clippings, and bagasse; the fibre is dispersed in the stock chest using a low-rpm agitator before forming to prevent entangling. Production consists of vacuum forming on porous metal moulds, transfer to a hot-press tool, and drying at 120–180°C depending on wall thickness; the structural fibre reduces tearing at thin-wall edges, as measured by internal tearing resistance per ISO 1974, and improves snap-through resistance of detailed locking features under compressive displacement according to ISO 12048:1994. Terminal product types are end-cap cushions, tray inserts, and replaceable protective packaging. Compliance for non-food packaging is typically REACH Regulation (EC) No 1907/2006; if the packaging is intended for short-term contact with dry or moist food, FDA 21 CFR 176.170 and EU 1935/2004 declarations may be required. Cushioning performance is often tested according to ISTA 3A or ASTM D4169-23 for distribution simulation; material strength is measured by tensile energy absorption of the dried pulp wall per TAPPI T494 om-22. A process limit is that VPB103 does not act as a mould-release agent and may adhere to unpolished tooling if the furnish is overdried; published data for this specific grade in moulded pulp tooling is limited.
Wet-lay separator substrates for alkaline cells use PVA structural fibre because the polymer structure can withstand the concentrated alkaline electrolyte environment better than many cellulosic reinforcing fibres, although qualification is required for each cell manufacturer. The application is narrow and process-intensive; published data for this specific configuration is limited, so qualification is typically performed on a pilot paper machine with a furnish containing 5–15 wt% VPB103, mercerized softwood pulp, and a wet-strength resin compatible with alkali. Formation is carried out on a cylinder former or inclined wire, followed by thin-film impregnation with an antioxidant or wetting-agent formulation, slitting, and roll packaging under low humidity; air permeability and absorption height are two critical separator metrics tracked on every parent roll. Compliance is covered by IEC 60086-2 for primary batteries and IEC 61951-1 for sealed nickel-cadmium cells where the separator is used in alkaline secondary systems; if the same furnish is adapted for absorbent glass mat separators in lead-acid batteries, IEC 61056-1 applies. Terminal product types are spiral-wound separator liners, positive electrode wrap in rechargeable alkaline cells, and absorbent retention layers in industrial cells. The process conflict is that VPB103 cannot be refined aggressively; high-consistency refining above 3.0% will cause fibre shortening and reduce the separator’s puncture resistance, so refining energy is applied exclusively to the cellulosic component before blending.
Decorative laminates and resin-impregnated overlay papers use VPB103 to support dimensional stability during resin impregnation and to limit sheet growth in the cross-machine direction when a melamine-formaldehyde resin is applied at high speed. Dimensional change is measured after water immersion per ISO 5635, and hygroexpansion of the base paper is monitored on a cross-machine strip before resin application. The addition ratio in decor base paper is commonly 2.0–5.0 wt% of the wood pulp furnish, but the maximum is set by opacity and formation; PVA fibre is less opaque than titanium dioxide and may produce a translucent patch if dispersion is poor, so opacity is monitored per ISO 2471. The production process is a fourdrinier or twin-wire machine running at 60–120 g/m²; the base paper is surface-treated with starch or PVOH at the size press, dried to 2–4% moisture, and later impregnated with an MF resin at the treater. Terminal product types are low-basis-weight overlay paper, furniture foil backing paper, and printed decor paper. Compliance for laminate flooring and furniture surfaces is defined by EN 438-3 for decorative high-pressure laminates and ISO 4586-2; resin content, ash, and air permeability are controlled to mill-specific specifications. A limitation is that VPB103 may lower retention of TiO₂ slurry if the retention system is not adjusted; continuous monitoring of headbox ash and machine-direction tensile ratio is required. Published data for the interaction of VPB103 with MF resin on high-speed thermoset lines is limited, so resin bath viscosity and dilutability must be revalidated after each fibre addition change.
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Kuraray VPB103 is a polyvinyl alcohol (PVA) structural fiber for paper making, supplied as a cut-fiber furnish additive rather than as a dissolved polyvinyl alcohol solution or powder. The fiber is a high-hydrolysis PVA homopolymer with a degree of hydrolysis above 98 mol%. The 103 designation identifies a papermaking-grade cut length of 3 mm and a low-temperature dissolution profile in neutral water; within the manufacturer’s KURALON PVA fiber range, VPB103 is positioned as a binder fiber that remains discrete through stock preparation and sheet forming, then activates during drying. This dual behavior contributes a reinforcing skeleton before thermal activation and adhesive film formation after the wet web reaches the dissolution threshold. Typical applications include wet-laid filter media, tea bag paper, decorative paper, and grades that require wet tensile without formaldehyde-based wet-strength resins. The lot certificate of analysis remains the controlling specification; the values below are manufacturer-published typical data.
The fiber is a non-fibrillating homopolymer with uniform cross-section and no sheath-core differentiation. This distinguishes VPB103 from sheath-core binder fibers because dissolution occurs across the entire fiber rather than only in a low-melting sheath. The product is not intended for melt processing; thermal softening in papermaking is water-mediated. Table 1 lists the typical lot properties.
| Property | Reported range or typical value | Test method |
|---|---|---|
| Chemical composition | polyvinyl alcohol homopolymer | manufacturer lot certificate |
| Degree of hydrolysis | 98–99 mol% | JIS K 6726 |
| Linear density | 1.0 dtex ± 0.1 dtex | ISO 1973:2021 |
| Cut length | 3.0 mm ± 0.5 mm | ISO 6989:1981 |
| Dry tenacity | 4.0–5.5 cN/dtex | ISO 5079:2020 |
| Elongation at break | 25–35% | ISO 5079:2020 |
| Wet tenacity retention | 70–85% of dry tenacity | ISO 5079:2020 wet condition |
| Density | 1.26–1.30 g/cm³ | ISO 1183-1:2019 |
| Complete dissolution temperature in neutral water | 60–70 °C | in-house method, 1 g/L, gentle agitation |
| Moisture regain at 65% RH | 4–5% | ISO 287:2017 |
| Ash content | ≤0.5% | ISO 1762:2019 |
| Thermal degradation onset | >200 °C | ISO 11358-1:2022 |
Variation in water hardness, pH, or dissolved salts can shift dissolution onset. Alkaline whitewater conditions may extract low-molecular-weight PVA fractions below the listed threshold. The product should not be predispersed in tanks equipped with steam sparging above 50 °C. Within the manufacturer’s VP series, the 103 grade is differentiated from higher-numbered binder grades primarily by dissolution temperature and cut length. Higher-activation PVA grades remain fibrous longer in the dryer and may be preferred where wet web strength must survive higher temperatures before bonding. VPB103 is also distinct from polyvinyl acetate emulsion binders and polyvinyl alcohol powder; the fiber form eliminates dusting, meters like a cellulosic furnish component, and creates a temporary reinforcement phase before dissolution. Because VPB103 dissolves uniformly, it should not be used where a non-dissolving reinforcing fiber is required throughout the finished sheet, since a portion of the fiber loses fibrous identity during drying.
The fiber is first dispersed in water at 10–25 °C; dissolution is negligible at this temperature, so conventional pulpers and machine chests are acceptable. Dispersion should avoid high-shear refining because VPB103 does not fibrillate and mechanical refining reduces fiber length and generates fines that dissolve prematurely. If refining is required for the cellulosic furnish, VPB103 should be introduced after refiners and before the machine chest. Dispersion consistency below 2 wt% in dedicated pulpers reduces agglomeration. Do not recirculate the dispersed fiber through centrifugal cleaners for extended periods, because fiber length can be lost; forward cleaners may remove some PVA fibers, although the density of 1.26–1.30 g/cm³ is less problematic than aramid or glass fiber.
Addition rates of 3–10 wt% on dry furnish are typical for specialty grades. Above 15 wt%, drainage and formation often degrade; published data for this specific configuration is limited. Retention is governed primarily by mechanical filtration and hydrogen bonding rather than charge neutralization because the fiber exhibits low surface charge density. In filled or high-freeness furnishes, a cationic polyacrylamide retention aid at 0.02–0.05% on dry fiber is typically used. Headbox pH should be maintained between 6.5 and 7.5. Acidic conditions below 4.5 promote acid-catalyzed hydrolysis; alkaline conditions above 9.0 increase surface swelling and can produce tacky deposits on forming fabrics. Whitewater loops operating with high closure may accumulate dissolved PVA oligomers, which raise foam stability and interfere with cationic demand titration. Defoamer dosage often requires adjustment because dissolved PVA is surface active.
On the forming section, the fiber behaves as a relatively stiff but non-fibrillating cut fiber. On a twin-wire former, typical retention efficiencies of 60–85% have been reported for similar cut-length synthetic fibers when the retention aid is applied in the thin-stock loop; actual values are furnish-specific and should be confirmed by mass balance. Wet web tensile before activation is lower than that of refined cellulosic furnish, so open draws should be set with reduced tension to prevent edge flutter and open-draw breaks. In press sections operating at linear loads of 80–120 kN/m, the PVA fiber flattens and increases interfiber contact, but excessive wet pressing to solids above 48–50% can reduce bulk and may make the sheet denser than required for filter and tea bag applications.
Activation of the fiber occurs in the dryer section when sheet temperature reaches approximately 60–70 °C and residual moisture still allows PVA chain mobility. Below 55 °C, the fiber remains largely intact and contributes mechanical entanglement rather than adhesive bonding. Above 70 °C, dissolved PVA migrates into interfiber contacts and forms film-like bridges upon drying. This transition creates a narrow processing window in the early dryer section. If the wet web contacts a dryer can hotter than 80 °C before its moisture content falls below 60%, PVA film can transfer to the can surface and cause picking. Mills running VPB103-containing grades therefore schedule a gradual drying ramp and may reduce first-group can temperatures by 10–15 °C relative to standard conditions. Calendering should be kept below 90 °C; higher surface temperatures can soften PVA at the sheet surface and produce blackening or sticking during machine stops. Final sheet moisture should remain within normal limits of 4–8% depending on basis weight and end use.
The following directional changes are commonly observed in PVA binder fiber systems; exact values are furnish-specific. In ISO 5269-2 handsheets from bleached softwood kraft at 5 wt% VPB103, dry tensile index measured by ISO 1924-2 can increase by 5–15% after thermal activation; wet tensile index rises more substantially because PVA film bridges fiber intersections. Bursting strength measured by ISO 2758 can increase by 10–20% in the same typical range, while tear index measured by ISO 1974 may remain unchanged or decrease slightly if the PVA bond restricts fiber pull-out. Air permeability measured by ISO 5636-3 decreases with increasing PVA content because the film-forming phase occupies interfiber pores; this is often desirable for tea bag and filter papers but can reduce absorbency. Wet tensile after 24 h water immersion remains higher than untreated cellulose but lower than high-dose melamine-formaldehyde or urea-formaldehyde wet-strength resin systems. PVA bonding is not covalent or thermosetting, so some loss under prolonged soaking should be expected. A 5 wt% addition can reduce Canadian Standard Freeness by 20–50 mL under ISO 5267-1, depending on refine level and filler content.
Deposit formation is the main process conflict. Dissolved PVA is surface active and can precipitate on felt surfaces if whitewater pH drops sharply or salt concentration increases. Mills counter this with nonionic felt detergents and periodic alkaline boil-outs. High doses of cationic fixatives should be avoided because PVA-fixative complexes can form white pitch-like deposits. Residence time in chests above 50 °C should be limited to 30–60 min; above 55 °C, the fiber surface becomes sticky and agglomerates can form in chest corners and on level sensors. Transfer lines after steam mixing points should be inspected for accumulated film if the furnish is heated before the headbox.
Compared to polyethylene terephthalate (PET) fiber, VPB103 offers a thermal response that is compatible with water-based papermaking rather than melt bonding. PET fiber has a melting point near 255–260 °C and does not bond to cellulosic fiber without an additional latex or sheath. Para-aramid fiber has no practical thermoplastic bonding window and is hydrophobic. VPB103 becomes adhesive at 60–70 °C only in the presence of water and can form bonds without latex, but this also limits high-temperature performance: PVA bonds soften under high humidity and are not suitable for continuous service above 120 °C. For food-contact paper, VPB103 is not a direct substitute for fluorochemical grease-resistance additives or for high-temperature aramid insulation papers. The choice between VPB103 and PET fiber often depends on whether the end product must survive hot humid conditions; PET maintains dimensional stability better above 120 °C, but VPB103 avoids the need for a latex binder in many wet-laid grades.
| Property | VPB103 | PET fiber | para-aramid fiber | refined softwood kraft |
|---|---|---|---|---|
| Density | 1.26–1.30 g/cm³ | 1.38 g/cm³ | 1.44 g/cm³ | 1.50 g/cm³ |
| Moisture regain at 65% RH | 4–5% | 0.4% | 3–7% | 8–12% |
| Thermal response in wet-laid drying | dissolves/softens 60–70 °C | melts 255–260 °C | degrades above 500 °C, no thermoplastic bond | no thermoplastic response |
| Bonding to cellulose | PVA film and hydrogen bonds | requires latex or binder fiber | none inherent | hydrogen bonding |
| End-use temperature ceiling | 120 °C under humid load | 150–200 °C depending on latex | 180–250 °C | 150 °C in dry air |
The comparative data are drawn from general polymer and fiber literature; the VPB103 values should be confirmed against the lot certificate because surface finish and degree of hydrolysis can shift dissolution and bonding. In direct substitution trials, a pilot-scale paper machine trial is necessary because formation, retention, and dryer deposition cannot be predicted solely from fiber properties. Published data for direct substitution of VPB103 in flame-retardant aramid papers is limited; if such a substitution is attempted, the upper service temperature and hot-wet tensile of the resulting paper will be controlled by the PVA fraction.
Open bales should be conditioned at 20–25 °C and 50–65% RH for at least 24 h before use to reduce static and feeding variability. If moisture exceeds 8%, the fiber may clump in metering screws; material exposed to RH above 80% should be pre-dried at 40 °C for 2–4 h. Storage near steam lines or open water is unsuitable. Borate-containing additives can crosslink dissolved PVA even at low concentrations and form gel specks; strong oxidizing agents such as hypochlorite above 500 ppm residual chlorine cause chain scission and loss of fiber tenacity. Prolonged exposure to pH above 10 at temperatures above 50 °C should be avoided. For food-contact paper, the product’s suitability must be established under FDA 21 CFR 176.170 and 176.180, with migration testing according to EN 1186-1 or equivalent. The current REACH status and specific SDS should be confirmed for each shipment.
Incoming inspection typically verifies cut length distribution by optical microscopy, linear density by ISO 1973:2021, and dissolution behavior by a hot-water check at 60 °C: a discrete fiber should lose its fibrous form within 10–15 min under mild agitation. This simple test distinguishes VPB103 from higher-activation PVA grades that remain discrete at 60 °C. Repulping of off-spec paper containing VPB103 is possible in hot pulpers above 60 °C; cold repulping will leave fibrous PVA fragments. Lot-to-lot cut length distribution should show a coefficient of variation below 15%. If wet tensile after thermal activation at 70 °C does not meet target, dryer temperature profile should be checked before increasing binder dose.
