Fibra ligadora Kuraray VPB107-1-PVA para fabricação de papel (dissolve a 70 ° C)

Where the wet-laid separator furnish exceeds 10 wt% VPB107-1, the process conflict is not dissolution temperature alone but the drying-rate threshold at which dissolved PVA migrates to the sheet surface before wet tensile develops. On a pilot inclined-wire line running 40 g/m² at 60 m/min, the first dryer section must hold the sheet core above 70°C for 8–15 s while the surface temperature remains below 95°C; if the surface temperature exceeds 110°C before the core reaches the dissolution point, a translucent PVA skin forms and air permeance measured by ISO 5636-3 can drop by 25–40%. The furnish typically comprises mercerized softwood pulp, synthetic fibrillated polyolefin, and 10–25 wt% VPB107-1, with the upper limit set by pore occlusion rather than dry tensile. At 25 wt%, the mean flow pore diameter as measured by capillary flow porometry using ASTM D6767 shifts downward because the dissolved PVA coalesces into film-like bridges across fiber intersections; at 8 wt%, the separator sheet survives slitting but fails alkaline cell assembly because the wet tensile after 30 min immersion in 40% KOH falls below the line release limit of 0.5 kN/m in ISO 1924-2. Production equipment for this grade is a low-consistency headbox operating at 0.3–0.5% consistency to prevent fiber flocculation, followed by vacuum dewatering boxes and a through-air dryer with a 70–80°C plateau zone. The papermaking line must be cleaned after each run because residual PVA deposits in the wire pit and shower screens re-dissolve in the next warm furnish batch, causing basis weight drift of ±1.5 g/m². Ambient relative humidity above 60% causes the cut fiber to pick up moisture and clump at the bale opener; pre-drying at 40°C for 2 h is required before feeding. Borate-containing dispersants or coating pigments are incompatible because borate complexes with PVA and shifts the dissolution point upward, leaving undissolved fiber at 70°C. A lot-to-lot shift of ±0.5 mol% in the PVA hydrolysis specification can change the dissolution cloud point by 2–4°C, which on a line running 100 m/min is enough to leave undissolved fiber bundles in the sheet and produce surface pilling at the calender. The terminal product is alkaline manganese dioxide cell separator base sheet, principally 12–40 g/m² grades, converted into bobbin and cup separator configurations. No single ISO standard governs PVA binder fiber in alkaline separators; converters require REACH confirmation under Regulation (EC) No 1907/2006 and rely on cell-level verification under IEC 60086-4. Mill release testing includes ISO 1924-2, ISO 5636-3, and a KOH immersion tensile method derived from ISO 1924-2.

What Limits PVA Fiber Addition in Heat-Seal Tea Bag Base Stock?

Addition is limited by the heat-seal window of the downstream converter rather than the PVA dissolution temperature. In heat-seal tea bag base paper at 12–16 g/m², VPB107-1 is introduced at 5–12 wt% of the furnish. The base sheet normally contains abaca, softwood kraft, and a heat-seal fiber such as polypropylene or polyester. If the PVA addition exceeds 12 wt%, the dissolved binder reduces air permeability and creates a continuous surface film that interferes with the heat-seal fiber melting at 160–190°C. At 5 wt%, the dry tensile improvement is measurable: production records on an inclined-wire machine with an 18 g/m² sheet show a 15–20% increase in dry tensile by ISO 1924-2 compared with a non-PVA control, but wet tensile after steeping remains below the target of 0.25 kN/m unless the machine uses a through-air dryer that brings the sheet core to 70–75°C before final can drying. The papermaking process is wet-laid on an inclined wire at 0.2–0.4% headbox consistency, dewatered by vacuum and wet press, then dried through a through-air unit with 110–130°C supply air to complete PVA film formation. The terminal products are heat-seal tea bag paper, coffee pod filter base stock, and herb pack overwrap paper, with basis weights from 12–25 g/m².

In automotive engine oil filter base stock, VPB107-1 is added at 5–15 wt% to provide dry-strength integrity before phenolic resin saturation, not as the final structural binder. The wet-laid papermaking process uses a fourdrinier or inclined wire with a furnish of softwood kraft, hardwood kraft, and possibly cotton linters, with the PVA fiber introduced in the machine chest after refining. If the addition is below 5 wt%, the sheet tears at the wet press transfer on machines running above 90 m/min; if it exceeds 15 wt%, the densified PVA film reduces porosity after corrugating, increasing initial pressure drop by 10–20% in engine test rigs. The production process after papermaking includes phenolic resin saturation at 18–25 wt% resin pick-up, curing at 150–170°C, corrugating, and pleating into cylindrical elements. Terminal products are full-flow automotive oil filter elements tested to ISO 4548-12 for filtration efficiency and collapse resistance. Compliance for the media itself is driven by the filter manufacturer’s material specification, which typically requires ISO 1924-2 dry tensile, ISO 536 grammage, and ISO 534 thickness, while the final element must satisfy ISO 4548-12 without media failure.

When PVA Binder Fiber Replaces Internal Size in Abrasive Backing Stock

Replacement of starch or latex internal size with VPB107-1 in abrasive backing paper requires addition of 3–8 wt% because higher levels reduce Sheffield smoothness after calendering. The base sheet is produced on a cylinder mould machine or fourdrinier at 80–120 g/m², using softwood kraft and eucalyptus with the PVA fiber added at the blending chest. The wet web is pressed to 40–45% solids before drying at 100–120°C; a separate surface size of starch or PVA is then applied, followed by calendering at 80–100 kN/m line load. The dissolved PVA contributes internal bond, measured by ISO 16260:2016, which is critical when the backing is coated with urea-formaldehyde or phenolic resin-based abrasive grain adhesive. At 8 wt%, internal bond improves by roughly 15–25% against a no-binder control, but Sheffield smoothness degrades because PVA film increases fiber-surface stiffness before calendering. The terminal products are coated abrasive backing paper for belts, discs, and sheets, where dimensional stability under coating tension is a release criterion. Compliance is through ISO 1924-2 tensile, ISO 16260:2016 internal bond, and ISO 5626 folding endurance; the coated abrasive manufacturer validates final products under its own FEPA-based or ISO coated-abrasive procedures, and REACH Regulation (EC) No 1907/2006 applies to the PVA substance.

For nonwoven wallpaper base stock, VPB107-1 is used at 2–7 wt% to maintain wet web runnability without producing a closed surface that rejects aqueous adhesive paste. The wet-laid process on an inclined wire forms a 50–80 g/m² sheet from softwood, cellulose, and synthetic fibers; the PVA binder dissolves at 70°C in the through-air dryer and imparts enough dry tensile for embossing and coating. Terminal products are paintable nonwoven wallpaper, duplex base for vinyl-coated wallpaper, and paintable wall covering. Compliance is under EN 15102:2007+A1:2011 for wallcoverings, with REACH Regulation (EC) No 1907/2006 and ISO 1924-2 tensile used in mill release.

Glass Fiber Filter Media and the 70°C Dissolution Window

Glass fiber filter media use VPB107-1 at 10–30 wt% because glass fiber furnishes generate almost no hydrogen-bonded wet strength and the PVA must function both as a processing aid and as a pre-saturation binder. The papermaking line is an inclined wire with a low-consistency headbox; dispersants such as polyacrylamide are added to the stock, and the sheet is dewatered gently to avoid glass fiber embrittlement at high vacuum. Dissolution is carried out in a through-air dryer where the sheet core must reach 70–75°C for 5–15 s; if the core temperature remains below 70°C, undissolved PVA fiber segments appear as non-fused bundles in the finished sheet and create pinholes after the downstream resin saturation. At 30 wt%, the dry sheet becomes stiff and the pressure drop rises; at 10 wt%, the sheet tends to split at the wet press on lines producing 40–80 g/m² HEPA media. The paper is then impregnated with a silicone or phenolic resin and cured to provide wet strength and high-temperature dimensional stability. The terminal products are glass fiber HEPA/ULPA filter media, analytical filter paper, and backing media for membrane supports. Compliance is anchored to EN 1822-1:2019 for the final filter element or media performance, while the paper mill release uses ISO 536, ISO 1924-2, and ISO 5636-3. REACH Regulation (EC) No 1907/2006 applies to the PVA substance and the finished media.