| HS Code | 937339 |
| Material | Polyvinyl alcohol (PVA) |
| Product Type | Water-soluble binder staple fiber |
| Application | Paper making / wet-laid nonwoven binder |
| Water Dissolution Temperature | 60°C |
| Typical Fineness | 1.7 dtex |
| Typical Cut Length | 2 mm |
| Typical Fiber Diameter | Approx. 13 µm |
| Typical Tensile Strength | Approx. 3.6 cN/dtex |
| Typical Elongation At Break | Approx. 35% |
| Density | Approx. 1.26 g/cm³ |
| Ph In Water Extract | Neutral |
| Bonding Function | Dissolves and acts as a binder between pulp/paper fibers after drying |
As an accredited Kuraray VPB105-2-PVA Binder Fiber for Paper Making (Dissolves at 60°C) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 20 kg multi-wall paper bags with an inner plastic liner, ensuring dry, stable storage until dissolution at 60°C. |
| Container Loading (20′ FCL) | 20′ FCL loading: palletized, sealed cartons of PVA binder fiber, dry and ventilated, protected from heat above 60°C. |
| Shipping | This water-soluble PVA binder fiber ships in sealed, moisture-resistant packaging to prevent premature dissolution. Protect from temperatures above 60°C, direct sunlight, and humidity during transit. Store in a cool, dry area. Non-hazardous, but handle with care to avoid fiber dispersion and static buildup. |
| Storage | Store in a cool, dry, well-ventilated area below 40°C, away from heat sources, open flames, and direct sunlight. Keep the original packaging tightly sealed to prevent moisture absorption, since the fiber dissolves at 60°C. Avoid contact with water, humidity, and incompatible chemicals. Use dry handling equipment and rotate stock to maintain performance. |
| Shelf Life | Shelf life is typically two years from manufacture when stored unopened, in a cool, dry environment away from moisture. |
For cellulose/polyester wet-laid filtration furnish destined for diesel intake elements and heavy-duty lubricating oil filters, VPB105-2 is introduced after refining at a loading screened between 4 wt% and 12 wt% of bone-dry fibre. The stock preparation circuit is held below 50°C because the PVA structure begins to soften as the furnish approaches 60°C, and premature dissolution in the pulper raises cationic demand, destabilises the retention package, and leaves the fibre unavailable for bond formation. Once the web has been formed on an inclined wire or rotary drum former at headbox consistency between 0.4% and 1.0%, the critical dissolution window occurs in the dryer section. The web must reach 60°C while free moisture is still present; if the moisture content falls below the saturation point of the non-PVA fraction before the wet sheet reaches 60°C, the binder fibre remains intact as a non-bonded filler, producing edge dust, low tensile, and poor converting yield. Multi-cylinder dryers are typically set with the first cans above 95°C, while through-air dryers run at 105°C to 120°C so the thermal front reaches the core of the sheet before the dry line. The dissolved PVA migrates to fibre intersections, forms film-like bridges, and consolidates the glass microfibre fraction without blocking the inter-fibre voids in the manner of an acrylic latex film. The finished sheet is tested under ISO 1924-2 for dry tensile, ISO 5636-3 for Bendtsen air permeance, ISO 5011 for air cleaner capacity and dust retention, and ISO 4548-12 for multi-pass particle retention in oil filtration. The binder is thermoplastic and will re-soften in hot water above 60°C; therefore the material is not suitable for aqueous service unless the sheet receives an external wet-strength resin or hydrophobic post-treatment after drying. Borated retention aids should be avoided because borate ions can crosslink dissolved PVA in the white water, increase deposit formation on dryer cans, and reduce formation quality. The applicable test matrix for this class of media is summarised below.
| Standard | Property | Equipment or condition |
|---|---|---|
| ISO 1924-2 | Dry tensile strength | Constant-rate elongation tester, 100 mm test span |
| ISO 5636-3 | Air permeance | Bendtsen apparatus, 1.47 kPa head |
| ISO 534 | Thickness and apparent density | Micrometer, 100 mm² presser foot |
| ISO 5011 | Air cleaner efficiency and dust capacity | Multi-pass air filtration test stand |
| ISO 4548-12 | Oil filter particle retention | Multi-pass hydraulic test rig with particle counter |
The substitution is most consequential on glass veil lines running without a size press, where the binder must develop sheet integrity before the veil is wound and shipped for resin impregnation. Glass fibre surfacing veils used in compression moulding, resin transfer moulding, and flooring overlay carriers are formed from wet chopped strand dispersed in white water, and VPB105-2 is added at 5 wt% to 10 wt% of dry furnish. Because the fibre remains solid in the cold dispersion zone, it can be metered into the mixing chest without the viscosity drift or shear instability associated with latex emulsions. The binder remains fibrous through dewatering and begins to dissolve only when the wet veil enters the hot-air arch, where the sheet reaches 60°C with moisture still present. The dissolved polymer collects at fibre junctions rather than coating each glass filament, which preserves open porosity and allows subsequent resin wet-out without the filming defects that a latex binder can produce at low grammage. Glass content is verified with ISO 1887, and binder loss on ignition is measured with ISO 1172. Veil producers should set the air arch above 110°C and avoid prolonged exposure above 140°C, because discolouration of PVA is possible when hot-air impingement continues beyond the evaporation of free moisture. A silane coupling agent added for laminate adhesion can interact with the dissolved PVA at the white-water stage; therefore the silane is best introduced by post-treatment or by a separate applicator rather than directly into the main mixing chest. The primary limitation is re-wet sensitivity: a finished veil that absorbs condensation or is rewetted during customer handling will lose bond strength below the level required for slitting and resin bath transport. Published data for this specific configuration is limited, but the failure mode observed in production is edge wrinkle and breakage at the resin bath guide rolls when the veil has been stored at relative humidity above 80% without a moisture barrier.
Ceramic fibre gasket stock is formed under low vacuum, high stock dilution, and minimal wet pressing because aluminosilicate fibres do not swell like cellulose and require a binder to generate sufficient cold tensile for die-cutting. VPB105-2 is added at 3 wt% to 6 wt% of dry fibre, and the wet web is dried on a cylinder or through-air system at 115°C to 125°C. The PVA fibre dissolves once the web reaches 60°C and deposits at the fibre contacts, producing a stiff sheet that can be cut into exhaust gaskets, kiln expansion joints, and backup insulation without cracking at the die edge. In service above 250°C the PVA binder pyrolyses; the burnout is relatively clean, and the residual ash is controlled by the inorganic content of the base fibre rather than the binder. Ash content is measured using ISO 1762 at 525°C, and cold tensile is measured using ISO 1924-2 before thermal exposure. A process conflict arises when gasket paper is densified too heavily in wet pressing: the collapsed pore structure retards the escape of pyrolysis gases during initial heat-up, and the binder may carbonise in the core instead of oxidising away at the surface. For this reason the wet-press load is kept low, and post-curing in air above 500°C is specified for parts that will operate in low-oxygen flanged assemblies. The PVA binder film is water-sensitive after drying, so the finished ceramic paper must be stored in dry conditions and protected from condensation before first fire. The cold tensile of the sheet is lost after burnout, but the ceramic fibre mat remains in place if the gasket is confined between flange faces. This trade-off is acceptable only in compression-loaded or contained gasket geometries; unsupported ceramic paper linings that require handling strength after burnout are outside the useful application window.
Carbon fibre paper for polymer electrolyte membrane fuel cell porous transport layers is wet-laid at a furnish pH between 4.0 and 5.5, with chopped carbon fibre dispersion assisted by a non-ionic surfactant and VPB105-2 added at 5 wt% to 15 wt% of dry furnish. The furnish temperature is held below 50°C so the PVA fibre remains solid through the headbox and wire section. Drying on a hot-air or cylinder system at 105°C to 130°C dissolves the binder and produces handleability required for roll-to-roll resin impregnation. The subsequent phenolic resin saturation and carbonisation step is the controlling process boundary. PVA decomposes in an inert atmosphere above 800°C, but published data for VPB105-2 in this exact gas diffusion layer configuration is limited; therefore gas diffusion layer producers qualify the material by measuring through-plane electrical resistance, porosity, and flexural integrity after carbonisation rather than relying on vendor-published bond strength alone. Ash content is checked by ISO 1762, with particular attention to sodium and calcium residues because saponification-derived salts can remain if the carbon fibre mat is not washed before impregnation. The PVA binder film is water-sensitive before carbonisation, so the wet-laid carbon sheet must not be exposed to condensation or high humidity during storage and slitting. The binder does not provide permanent bonding after the carbonisation stage; its function is limited to green strength and dimensional stability through the resin bath. Process trials should therefore focus on the relationship between binder addition, sheet density, and resin penetration depth, because an over-densified green sheet produces resin-starved interiors after carbonisation, while an under-bonded sheet breaks during resin bath tension.
Low-basis-weight overlay paper for high-pressure decorative laminates is converted through separate impregnation and pressing operations, and the furnish is refined harder than standard printing paper to produce a closed, uniform sheet. VPB105-2 is added at 5 wt% to 10 wt% to high-alpha cellulose pulp before final dilution, and the stock passes to a fourdrinier or inclined wire at low headbox consistency. The binder fibre dissolves during drying at 60°C and contributes internal bond and surface strength that reduce linting and fibre pick during the wet melamine-formaldehyde resin bath. Dry tensile is measured with ISO 1924-3, tearing resistance with ISO 1974, and laboratory sheets are formed under ISO 5269-2 before production wet-end optimisation. The PVA film re-softens in water, but after resin impregnation and thermoset lamination the binder is encapsulated in the cured laminate structure and no longer controls the wet performance of the finished panel. A processing boundary is reached when the overlay sheet is overdried: if moisture falls below 1.5% to 2.0% after drying, the PVA film becomes brittle and the sheet can crack at the impregnation station. Conversely, residual moisture above 3.0% can soften the PVA bonds and reduce the fibre pick resistance that is the main reason for using the binder fibre. The addition level is therefore balanced against final moisture and resin pickup. The binder is compatible with melamine-formaldehyde and urea-formaldehyde resins, but high pH resin baths above 10 can gradually dissolve residual PVA and increase bath viscosity; bath pH is therefore controlled in the 7.5 to 9.0 range on production lines using this fibre type.
On high-shrinkage wet-clutch friction lines, the furnish contains cellulose, aramid pulp, diatomaceous earth, and carbon particles, and the PVA fibre is used as a green-strength binder before phenolic resin saturation. VPB105-2 is added at 3 wt% to 8 wt% of total dry furnish, and the sheet is formed on a long-wire or cylinder machine at basis weights from 150 g/m² to 600 g/m². During drying, the fibre dissolves at 60°C and forms localised bonds that hold the high-filler sheet together through die-cutting and resin bath handling. Unlike latex binders, the dissolved PVA does not migrate to the sheet surface during drying under high airflow, because the polymer is already distributed within the furnish as discrete fibres. The absence of surface film formation preserves the open pore network required for oil flow in a wet clutch pack. Dry tensile is measured with ISO 1924-3, thickness and density with ISO 534, and ash content with ISO 1762 to confirm that filler retention has not been compromised by binder addition. The main process risk is premature dissolution in the stock system: if the pulper temperature exceeds 55°C, the PVA fibre softens and adheres to the refining plates, reducing refining efficiency and creating fibre bundles that appear as surface defects in the finished friction paper. The binder film is soluble in hot water, which is irrelevant in oil-immersed service but means that water-based cleaning of uncured friction sheet must be avoided before phenolic saturation. The binder does not continue to bond at elevated clutch temperatures; the cured phenolic resin provides the thermal and mechanical performance of the finished friction plate. Resin pickup measured after saturation should therefore not be used as an indirect check of PVA content, because the PVA fibre influences green strength and die-cutting behaviour rather than the final cured coefficient of friction.
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Kuraray VPB105-2 PVA Binder Fiber for Paper Making, specified to dissolve at 60 °C, is a polyvinyl alcohol fiber supplied for wet-laid papermaking and nonwoven processes. The grade is designed to place its activation point inside the drying section of conventional paper machines while requiring controlled wet-end temperature below 45 °C. The product is typically supplied as a 1.0 dtex fiber cut to 5 mm; because fineness and cut length control retention and bridging, incoming fiber dimensions should be checked against the certificate of analysis and the actual furnish. In wet-laid systems, VPB105-2 contributes dry tensile, internal bond, and surface integrity without the emulsion destabilization and volatile organic compound load associated with latex binders.
The polymer backbone is a fully hydrolyzed PVA, with hydrolysis degree for low-temperature water-soluble grades typically in the range 98.0–99.0 mol%. The dissolution response is not a melt transition; it is the solvation of a semicrystalline PVA structure and is governed by water temperature, shear, pH, and residence time. At neutral pH, macroscopic dissolution begins near 60 °C, but stock temperatures above 45 °C can soften the fiber and increase tackiness on forming fabrics. Because the gap between the safe wet-end limit and the activation threshold is only 15 °C, the grade has a narrower processing window than high-dissolution PVA binder fibers.
At 5 mm and 1.0 dtex, VPB105-2 is long enough to bridge multiple cellulosic fibers but fine enough to distribute across the sheet without severe wire marking. The 60 °C dissolution threshold distinguishes VPB105-2 from general-purpose PVA binder fiber grades that require 80–95 °C. The lower threshold can reduce steam demand in the dryer section; however, it also eliminates the option of running a hot wet end. Recirculated white water above 50 °C may initiate dissolution in chests, causing viscosity build-up and couch roll adhesion. Stock temperature should therefore be measured at the fan pump discharge rather than inferred from the machine chest setpoint.
Wet-end addition rates for binder fibers typically range from 3 wt% to 10 wt% on bone-dry furnish, depending on target strength and porosity. VPB105-2 is normally added after refining and close to the fan pump, because extended exposure to refiner temperature and mechanical shear can shorten fiber length and accelerate dissolution. Retention is primarily mechanical, but dissolved PVA can increase anionic load in the white water, measurable with a particle charge detector, and reduce retention aid efficiency. Jar tests with mill stock and white water are required before changing retention aid dose. Freeness and drainage should be monitored according to ISO 5267-1 or with a dynamic drainage analyzer when addition levels exceed 5 wt%.
Compared with latex binders, VPB105-2 is a dry, repulpable fiber additive. Latex emulsions introduce film-forming polymer into the wet sheet and can reduce bulk and increase drying energy. VPB105-2 remains in fiber form through the forming section and activates only in the dryer, preserving wet-web openness and depositing binder preferentially at fiber crossings. Against starch or cellulose nanofibrils, VPB105-2 adds synthetic fiber bridging and does not increase refining load; however, it does not provide the same surface sizing or cationic demand response, so the wet-end programme must be recalibrated.
Another relevant comparison is with thermoplastic bicomponent binder fibers. Those fibers require melt bonding at 130–160 °C and form discrete bond points without water interaction. VPB105-2 instead solubilizes in water at 60 °C and reprecipitates into a continuous adhesive phase. The selection between them depends on whether the process can tolerate water-based binder migration and whether the product must be repulpable. In repulpable paper grades, VPB105-2 is often preferred because it does not leave a thermoplastic melt residue; in dry-laid nonwovens, bicomponent fibers are commonly preferred because the web can be bonded without adding water.
| Parameter | VPB105-2 | High-dissolution PVA binder fiber | Latex binder |
|---|---|---|---|
| Nominal dissolution temperature | 60 °C | 80–95 °C | No fiber form; film formation during drying |
| Typical fineness | 1.0 dtex | 1.0–2.2 dtex | Not applicable |
| Typical cut length | 5 mm | 4–6 mm | Not applicable |
| Recommended maximum approach-system temperature | 45 °C | 60 °C | Not applicable |
| Activation mechanism | Fiber dissolution and reprecipitation | Fiber dissolution and reprecipitation | Emulsion film formation |
| Repulpability after drying | High; dissolved PVA remains in water | High; dissolved PVA remains in water | Moderate |
In filtration grades, binder addition is evaluated against tensile index, air permeability, maximum pore size, and dusting. Handsheets should be formed according to ISO 5269-2 and tensile index measured according to ISO 1924-2; air permeability can be tested according to ISO 5636-3. Because VPB105-2 activates only when the sheet reaches 60 °C, the binder film is concentrated at fiber crossings rather than across the full surface. This can preserve air permeability at a given tensile level, but the response is furnish-dependent. Published data for this specific product in filtration grades is limited; direct side-by-side handsheet trials are recommended before commercial use.
Strength verification should use ISO 1924-2 for tensile index and ISO 16260 or TAPPI T 569 for internal bond. Burst strength can be measured according to ISO 2758. These methods should be applied to handsheets formed from the production furnish, not only to finished sheet samples, to separate fiber effects from machine-direction orientation and basis-weight variation.
Dryer-section activation requires the sheet temperature, not the dryer can surface temperature, to exceed 60 °C. On multi-cylinder dryers, the sheet may remain near the wet-bulb temperature during the constant-rate drying phase; measurable activation usually begins after free water has been removed and sheet temperature climbs in the falling-rate phase. In through-air dryers, exhaust temperature can overstate sheet temperature. Infrared pyrometry or contact thermocouples on the sheet are preferred for process verification. Once activated, PVA forms an adhesive phase at fiber intersections; excessive drying can darken cellulosic furnishes and consume steam without proportional strength gains.
Quality control for incoming VPB105-2 should include dissolution onset, linear density, and cut length. The dissolution temperature is commonly determined by controlled heating of a fiber suspension and observation of fiber disappearance, or by differential scanning calorimetry. Linear density can be tested according to ISO 1973, and fiber length by optical fiber length analysis. Hot water insoluble residue after treatment at 60 °C can indicate whether drying-section temperature was insufficient or whether fiber crystallinity differs from the standard grade. Batch-to-batch variance in dissolution onset can shift activation by a few degrees; mills should compare incoming lots when dryer conditions are fixed.
Because VPB105-2 is a fiber, its addition changes furnish freeness and formation. At addition levels below 5 wt%, the effect on formation is usually small; at levels above 10 wt%, the longer fiber component can produce wire marks if the stock is not adequately dispersed. Headbox consistency and jet-to-wire ratio should be adjusted when the binder fiber dose is increased. Formation can be evaluated with a beta-radiographic formation tester or visual formation standards; sheet grammage and thickness should be measured according to ISO 536 and ISO 534 so that basis-weight variation does not obscure the strength response.
The difference between 60 °C and 80–95 °C activation should be quantified against dryer-section steam consumption, not assumed. A mill trial can compare steam demand at constant machine speed and basis weight with VPB105-2 versus a high-dissolution PVA grade. Because lower activation may allow reduced dryer steam pressure or increased machine speed, the economic comparison should also measure strength development at the reel. Published mill energy data for this specific grade is limited; direct measurement is required.
Because VPB105-2 is water-soluble, broke repulping is generally straightforward under neutral or alkaline conditions. However, dissolved PVA remains in the white-water loop and can increase chemical oxygen demand and viscosity if the mill operates with a closed water system. Mills with low purge rates should monitor white-water total organic carbon and viscosity before increasing addition rates. For food-contact paper and paperboard, use of PVA binder fibers must be confirmed against the relevant regulatory framework, such as FDA 21 CFR 176.170 or FDA 21 CFR 176.180, or applicable national legislation. Compliance is formulation-dependent; the fiber supplier’s regulatory statement should be obtained for the specific furnish and end use.
On inclined-wire wet-laid lines and cylinder paper machines, premature dissolution has been observed when stock chests are located near dryer hood exhaust or when warm white water returns directly to the machine chest. The failure mode typically appears as sticky deposits on couch rolls and reduced fabric drainage. Operators can reduce this risk by isolating VPB105-2 addition to the fan pump, using cold fresh water for dilution, and bypassing hot broke storage during trials. These measures are more important when the machine operates with high white-water closure.
Do not combine VPB105-2 with borate-containing additives in the wet end unless a compatibility trial has been completed. Borate ions can complex with dissolved PVA and generate high-viscosity gels that foul forming fabrics and press felts. Cationic retention aids may also interact with dissolved PVA under high shear; optimal dose should be determined by drainage tests using ISO 5267-1 or a dynamic drainage analyzer. The approach system should be maintained below 45 °C, and the fiber should be stored dry below 30 °C and protected from high humidity to prevent blocking.
