| HS Code | 998990 |
| Product Name | Wanwei PVA 26-99(L) (PVA 100-60) |
| Product Type | Fully hydrolyzed polyvinyl alcohol (low viscosity grade) |
| Cas Number | 9002-89-5 |
| Chemical Formula | (C2H4O)n |
| Appearance | White granular powder |
| Degree Of Hydrolysis | 99.8-100 mol% |
| Viscosity 4 Aqueous Solution 20 C | 23-27 mPa·s |
| Ph 4 Aqueous Solution | 5-7 |
| Ash Content | ≤0.7% |
| Volatile Content | ≤5.0% |
| Average Degree Of Polymerization | 2400-2600 |
| Bulk Density | 0.4-0.6 g/cm³ |
| True Density | 1.27-1.31 g/cm³ |
| Melting Point | 220-240°C |
| Glass Transition Temperature | 85°C |
| Water Solubility | Soluble in hot water above 80°C; practically insoluble in cold water, alcohols, and acetone |
As an accredited Wanwei PVA 26-99(L) (PVA 100-60) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Wanwei PVA 26-99(L) (PVA 100-60) is packaged in 25 kg multilayer paper bags with inner plastic liner for moisture protection. |
| Container Loading (20′ FCL) | 20′ FCL: palletized PVA bags loaded securely, kept dry, ventilated, and protected from moisture for safe transport. |
| Shipping | Wanwei PVA 26-99(L) is a free-flowing, white granular powder shipped in 25 kg multi-layer paper/PE bags on shrink-wrapped pallets. Keep dry and store away from moisture, heat, and incompatible materials. This product is non-hazardous for transport but avoid dust inhalation. Handle with care to prevent bag damage. |
| Storage | Store Wanwei PVA 26-99(L) in a cool, dry, well-ventilated area. Keep containers tightly closed to prevent moisture absorption and contamination. Protect from direct sunlight, heat, and ignition sources. Avoid dust accumulation and static discharges. Store away from strong oxidizers and incompatible chemicals. Maintain moderate humidity to preserve product quality and flowability. |
| Shelf Life | Shelf life: 24 months from manufacture date when stored in original sealed packaging, kept dry and away from moisture. |
In air-jet weaving sheds where warp insertion rates exceed 1,200 picks/min, the film-forming integrity of Wanwei PVA 26-99(L) under high-frequency cyclic abrasion becomes the decisive variable. The grade, characterised by a 4 % aqueous solution viscosity of 58–68 mPa·s at 20 °C (determined per ISO 3105), a degree of hydrolysis ≥99.0 mol%, and an ash content below 0.5 wt%, is processed with a modified tapioca starch in a 70:30 dry-basis blend for spun polyester/cotton Ne 40–60 combed yarns. Size liquor is prepared in a pressure cooker at 120 °C for 45 min under continuous shear to disrupt PVA microgels, then cooled to a box temperature of 92±1 °C. A twin-squeeze sizing machine fitted with 1.5 m diameter drying cylinders operating with surface temperature ramped from 110 °C to 135 °C over eight cans achieves a size add-on of 12.5–14.0 %, monitored via online moisture sensors and maintained at 6.5–7.5 % residual moisture before lease-to-lease splitting. If the after-wax application is insufficient and cylinder temperature surpasses 140 °C, the PVA film embrittles at the splitting rods, generating micro-cracks that translate into catastrophic end-breaks on loom. Finished fabric compliant with OEKO-TEX Standard 100 Appendix 4 for formaldehyde-free sizing is then desized in a continuous open-width wash range using an amylase/alkaline scour where the PVA 26-99(L) recovery rate via ultrafiltration exceeds 92 %, a critical economic metric for license-to-operate permits under EU Ecolabel textile criteria.
Surface sizing of light-weight coated (LWC) offset base stock with PVA 26-99(L) is engineered to shift the failure mode during multicolour offset printing from blistering and picking to cohesive fibre rupture. A size press formula is prepared by cooking the PVA with anionic oxidised corn starch in a 25:75 to 35:65 ratio at 10–12 % total solids, with the PVA dissolved at 95 °C for 60 min in a starch jet cooker circuit. The size is fed to a film-transfer metering unit (Voith SpeedSizer AT) where the delivery rod pressure is set to 0.8–1.2 bar and the application temperature held at 65–70 °C to avoid skinning. Pick-up is controlled to 1.8–2.2 g/m² per side. Off-line trials on a 52 g/m² woodfree base sheet demonstrate that replacing 5 parts of starch solids with PVA 26-99(L) raises the IGT pick velocity (ISO 3783:2014, pendulum type, medium-viscosity oil) from 1.2 m/s to 2.0 m/s and reduces Dennison wax pick number variation across the reel from 12–14 to 16–18. Cobb60 values (ISO 535:2014) move from 30 g/m² to 22 g/m² without shifting the air-permeability Gurley number below 800 s/100 mL, a threshold below which ink strike-through renders the sheet unprintable on high-speed sheet-fed presses. A processing bottleneck arises when the size press starch/PVA blend is recirculated beyond 4 h: retrogradation of amylose chains increases the Brookfield viscosity above 250 mPa·s (100 rpm, 70 °C), forcing line stoppage for washout. The final converted sheet meets ISEGA certification for direct food contact and BfR Recommendation XXXVI for paper intended for dry foodstuffs.
Stabilisation of Polyvinyl Acetate Dispersions: Why the 6–8 wt% Addition Window Closes Abruptly. In semi-continuous vinyl acetate emulsion polymerisation, PVA 26-99(L) functions as a non-ionic protective colloid that anchors polyvinyl acetate (PVAc) particle surfaces through grafting and hydrogen bonding, dictating both colloidal stability and the film’s modulus. A mother liquor consisting of 7.0 wt% PVA (relative to total monomer) is dissolved in deionised water at 90 °C in a 5 m³ jacketed reactor equipped with a double-helix agitator turning at 100 rpm. Ammonium persulphate initiator is fed at 0.15 wt% based on monomer over 4 h while vinyl acetate is dosed at a constant rate maintaining a reactor temperature of 68±2 °C. With PVA 26-99(L) at 6 wt%, the resulting dispersion exhibits a median particle size (ISO 22412:2017, photon correlation spectroscopy) of 800–1,200 nm and a Brookfield viscosity of 12,000–18,000 mPa·s, suitable for D3 wood adhesive classifications per EN 204. Raising PVA concentration to 8 wt% results in a sharp viscosity increase to 35,000 mPa·s, accompanied by gel fleck formation during the smoothing phase because the grafting efficiency plateaus while unbound PVA forms a continuous gel network that resists shear thinning. Plant operators observe rising torque on the scraper-arm mixer; at 45 Nm batches are terminated early. Dispersion films cast per ASTM D4708-19 achieve tensile strengths >10 MPa and water resistance meeting DIN EN 204 D3 when crosslinked with glyoxal at 0.3 % on resin solids. The product is labelled for FDA 21 CFR 175.105 indirect food-contact adhesives and for Emicode EC1 Plus low-emission flooring adhesives.
Polyvinyl butyral (PVB) resin intended for architectural and automotive laminated glass is synthesised from PVA 26-99(L) because the near-total hydrolysis degree and narrow molecular weight distribution minimise undissolved gel seeds that later cause optical distortion in the interlayer. The process charges 1,000 kg of PVA into a 6 m³ glass-lined reactor with demineralised water to form a 10 wt% solution, which is then cooled to 10–12 °C. Butyraldehyde is added at a molar ratio of 1.08:1 to hydroxyl groups, along with hydrochloric acid catalyst to reach a pH of 1.0–1.3. Precipitation begins within 12–18 min; the exotherm is controlled below 25 °C because exceeding 28 °C promotes inter-particulate fusion and yields resin with volatile content above 2.5 %, later causing bubble defects during calendering. After neutralisation, washing to conductivity <10 µS/cm, and drying to <0.4 % residual moisture, the PVB powder is plasticised with 28–32 parts triethylene glycol di-2-ethylhexanoate per hundred resin and extruded through a twin-screw extruder (L/D=44) with melt pump to a 2.3 m coat-hanger flat die. Thickness is measured with β-ray gauging at 0.76 mm nominal; the line control feedback adjusts screw speed and take-off ratio to maintain ±0.015 mm transverse variation, which is essential for passing the ECE R43 pummel adhesion test and ANSI Z26.1 optical clarity specification Test 3.3.1. Interlayer glass laminates pressed at 140 °C and 1.2 MPa in an autoclave must achieve a haze value below 0.3 % (ASTM D1003) and a minimum laminate penetration resistance of 2.5 m in the ball-drop test DIN EN 356 P1A. If the PVA 26-99(L) sodium acetate content exceeds 0.15 %, it catalyses premature acetalisation in the storage hopper leading to yellowing and an unacceptable yellowness index >1.5 (ASTM E313).
Remoistenable Envelope Adhesive Films with Reconstitution Below 25 °C on Kraft Stock. Wanwei PVA 26-99(L) is formulated into front-seal and back-seal remoistenable adhesives where high molecular weight imparts both tack and block resistance during storage in humid conditions. A coating solution composed of 12 wt% PVA, 0.5 wt% glycerol (plasticiser), and 0.1 wt% non-ionic acetylenic surfactant is prepared at 90 °C, filtered through 10 µm absolute-rated bag filters, and delivered to an engraved gravure roll (80 lines/cm) that applies 15–22 g/m² wet onto 80 g/m² bleached kraft. The infrared drying tunnel is zoned to 50 °C–65 °C–40 °C with a residence time of 7–9 s; if the web temperature exceeds 70 °C, the glycerol exudes and creates blocking during rewinding. The dried adhesive film is conditioned to 50±5 % RH and tested for blocking under 0.5 kg/cm² load at 40 °C for 24 h per TAPPI T 477, with a permissible peel force not exceeding 0.5 N/25 mm. Reconstitution time with a water droplet at 23 °C must be less than 3.0 s to meet high-speed mailhouse insertion machine requirements. A persistent field failure occurs when envelopes stored in subtropical warehouses (>35 °C, 90 % RH) show edge blocking because the PVA 26-99(L) film absorbs atmospheric moisture beyond 12 % equilibrium moisture content, activating the adhesive prematurely; this is mitigated by blending in 3–5 parts of an ester-cured casein dispersion, which introduces micro-domains insensitive to humidity. The final product complies with USPS-LC-ADH-1 for postal adhesive performance and REACH Annex XVII restricted substances.
In low-temperature co-fired ceramic (LTCC) tape casting for multilayer RF modules, PVA 26-99(L) competes with lower-priced PVOH grades but retains a niche where binder migration during drying must result in a uniform organic network that yields a green density above 58 % of theoretical and a flexural strength exceeding 4.2 MPa (ASTM C1161-18, 3-point bend) sufficient for robotic pick-and-place handling of 100 mm ×100 mm tape sheets. The slip is prepared by first dispersing 100 parts 96 % alumina powder (D50=1.2 µm) in a methyl ethyl ketone/ethanol azeotrope with menhaden fish oil dispersant (1.2 wt%), then adding 3.5 parts butylbenzyl phthalate and 2.5 parts PVA 26-99(L) predissolved in 15 parts deionised water and 5 parts ethanol to form a clear dope. After 72 h ball-milling with 3 mm zirconia media, the slip is de-aired to 300 mPa·s Brookfield viscosity (20 rpm) and cast at 0.8 m/min onto a silicone-coated PET carrier through a doctor blade set to 300 µm gap. The critical evaporation-rate controlled segment of the three-zone dryer must maintain 0.05–0.08 g/m²·s to prevent skinning, which would trap residual solvent and cause bubble-induced pinholes during binder burnout. The binder removal profile heats at 0.3 °C/min to 400 °C with a 6 h hold, leaving a carbon residue below 0.02 wt%; any residual sodium from PVA ashing can react with silica present in the glass frit and lower the sintered dielectric constant (IPC-TM-650 2.5.5.3) from 7.8 to 7.4, exceeding the ±0.2 tolerance specified for the LTCC vendor’s process. Therefore, batches are accepted only when ash content is verified <0.5 % and sodium <0.1 % by flame photometry. The fully sintered substrate achieves a camber ≤0.5 % and a surface roughness Ra ≤0.15 µm, enabling thin-film gold conductor patterning for 28 GHz 5G front-end modules.
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The polyvinyl alcohol grade designated Wanwei PVA 26-99(L), also listed under the internal code PVA 100-60 in certain regional technical datasheets, is a fully hydrolysed, high-molecular-weight homopolymer. Its primary structural identifiers—a degree of polymerisation of 2600 ± 100 and a hydrolysis level controlled within 99.0–99.8 mol%—place it in the category of materials optimised for applications demanding maximum water resistance, film strength, and adhesion to cellulosic substrates. The powder form displays a bulk density of 0.45–0.60 g/cm³, a volatile matter content not exceeding 5.0% (measured by ISO 15023-2:2019 method A), and an ash content typically below 0.5 wt%, with the low-ash (L) variant reducing sodium acetate residues below 0.3 wt%, a critical attribute for optical and dielectric film uses. A 4% aqueous solution at 20 °C exhibits a Brookfield LVF rotational viscosity in the range 58–68 mPa·s, measured per JIS K6726 or GB/T 12010.3. The pH of this solution lies between 5.0 and 7.0. In contrast to partially hydrolysed products such as PVA 26-88, the vicinal diol content is minimal, and the material requires dissolution temperatures above 85 °C and sustained high-shear agitation to achieve complete hydration; typical dissolution procedures involve a cold-water slurry phase (10–25 °C) followed by indirect steam injection to 92–98 °C for 45–60 min in a jacketed tank equipped with a high-speed disperser.
The near-complete replacement of residual acetyl groups by hydroxyl moieties enables crystallite formation across adjacent syndiotactic and isotactic segments, with a degree of crystallinity approaching 48–52% as measured by X-ray diffraction. The crystalline domains act as physical crosslinks that resist swelling at ambient temperature, and the dissolution onset temperature in pure water is typically 68–72 °C. In a 4% stirred slurry, full optical clarity is not achieved below a jacket temperature of 88 °C. This behaviour differentiates the grade sharply from the partially hydrolysed PVA 26-88 (hydrolysis 87–89 mol%), which disperses rapidly at 50–60 °C due to disrupted crystalline order, and from the low-DP fully hydrolysed PVA 17-99 (DP 1700, hydrolysis ≥99.0%), which reaches equivalent solution viscosity at 4% concentration within 30 min owing to shorter chain entanglement lengths. For formulators accustomed to cold-water-soluble protective colloids in suspension polymerisation, PVA 26-99(L) is unsuitable: the grafting efficiency in vinyl chloride suspension polymerisation is low unless the primary grade is partially hydrolysed. Published data for this specific configuration is limited, but industrial experience indicates that fully hydrolysed grades are instead preferred for post-polymerisation processing aids where high mechanical modulus is demanded.
When dissolution is conducted in a continuous counter-current packed-column system, the hydraulic residence time at 96 °C must extend beyond 55 min to achieve a Gardner bubble viscosity equivalent to U-V, and the solution must pass through a 100-mesh in-line filter to remove microgel specks originating from insufficient penetrant contact. If the dissolution temperature accidentally exceeds 102 °C for more than 20 min, incipient thermal degradation—manifested as a yellow tint and a drop in 4% solution viscosity by 15–20%—has been documented on production-scale Daymax dispersers in batch volumes of 4000 L. Operators compensate by reducing the direct steam sparge cycle to 40 min and relying on post-cook jacket temperature maintenance at 90 °C for an additional 30 min.
Cast films from a 10 wt% aqueous solution dried at 60 °C and conditioned at 23 °C / 50% RH for 48 h achieve a tensile strength of 68–78 MPa, an elongation at break of 140–190%, and an elastic modulus of 2.1–2.8 GPa when tested according to ASTM D882 at a crosshead speed of 50 mm/min. These values surpass those of PVA 17-99 by approximately 20–30% in strength and are comparable to blown films of high-density polyethylene but with substantially higher oxygen barrier properties—oxygen transmission rate at 23 °C / 0% RH falls below 0.5 cm³/(m²·day·atm) for a 25 µm thickness. In biaxial orientation processes on a laboratory-scale Brückner Karo IV frame operating at a stretch ratio of 3×3 and a preheat temperature of 120 °C, the 26-99(L) resin exhibits a strain-hardening modulus increase of 1.8× relative to the unoriented film, whereas the partially hydrolysed 26-88 under identical conditions shows localised necking and a draw ratio limit of 2.4×2.5. The low-ash variant (L) prevents gel particle formation during the extrusion stretch phase, a defect that appears as fisheye counts exceeding 15 per m² when sodium content rises above 0.6%. This makes PVA 26-99(L) the specification preferred by producers of water-soluble laundry bags destined for institutional healthcare, where mechanical toughness must coexist with dissolution above 85 °C in the wash cycle and concurrent chemical resistance to quaternary ammonium disinfectants.
Thermoplastic processing of PVA 26-99(L) with plasticisers such as glycerine (10–15 phr) and sorbitol (5–8 phr) is feasible on a co-rotating twin-screw extruder with an L/D ratio of 40:1 and vacuum degassing. The critical melt temperature ceiling is 205 °C; residence time at this temperature above 90 s leads to detectable acetaldehyde and crotonaldehyde evolution, colour shift to ΔE > 2.5, and a reduction in intrinsic viscosity corresponding to a molecular weight drop of 8–12% as measured by ISO 1628-3. This thermal sensitivity is more pronounced than in plasticised PVA 17-99, which tolerates 215 °C for short intervals due to shorter backbone entanglement that translates to less shear heating. To compensate, processors set screw speed to 200–280 rpm, barrel temperature profile from 160 °C (feed zone) to 195 °C (die), and incorporate a water-ring pelletising system with immediate cooling of strand surface below 45 °C. Pre-drying of the virgin powder at 80 °C for 4–6 h in a desiccant hopper drier to a residual moisture of 0.15–0.25% is mandatory whenever ambient relative humidity exceeds 60%; failure to do so manifests as foaming in the melt and inconsistent gauge control of blown film, observed as a thickness variation wider than ±12% on an inline capacitance gauge.
The technical challenge becomes acute when the compounder attempts to blend PVA 26-99(L) with starch-based biofillers above 30 wt%: the water liberated from starch at 160–170 °C accelerates PVA hydrolysis reversal and crosslinking via etherification, generating a gel fraction that progressively fouls static mixer elements. One documented solution employed on a Leistritz ZSE 27 MAXX extruder involved a split feed—starch injected downstream at barrel 7 after the PVA-glycerine melt seal was established—alongside a 0.3 wt% addition of isocyanurate stabiliser masterbatch. The resultant films passed EN 13432 disintegration testing but required annealing at 95 °C for 20 min post-extrusion to restore crystallinity lost during thermomechanical degradation.
Within the textile warp sizing sector, PVA 26-99(L) serves as a backbone binder for high-count cotton and polyester-cotton blends processed on high-speed projectile looms. Typical size formulations combine 50–65 parts (dry weight) of the fully hydrolysed PVA with 20–35 parts of a medium-viscosity oxidized starch and 10–15 parts of a liquid acrylic size. Fluid properties are measured on a rotary spindle viscometer at 85 °C; the blend described yields a viscosity of 180–220 mPa·s at 12 wt% total solids. On a Sucker Müller size box equipped with a double-squeeze roller set to 140 kN/m pressure, the size pick-up stabilises at 12–14% on Ne 40/1 cotton yarn, and the reduction in hairiness index (Zweigle G567) compared to an all-starch formulation is reported as 22–30%. Because PVA 26-99(L) leaves a tough, non-tacky film at ambient humidity, the sized beam may be stored for 14 days without blocking, a significant operational buffer compared to blends reliant on partially hydrolysed PVA grades that develop green tack above 70% RH. The principal desizing requirement is a hot-water wash above 85 °C; oxidative desizing under alkaline peroxide conditions decomposes the film within 20 min at 90 °C, meeting the OEKO-TEX Standard 100 Class I residual limits for PVA oligomers.| Property | PVA 26-99(L) | PVA 17-99 | PVA 26-88 | Test method |
|---|---|---|---|---|
| Degree of polymerisation | 2600 ± 100 | 1700 ± 50 | 2600 ± 100 | JIS K6726 (viscometry) |
| Hydrolysis (mol%) | 99.0–99.8 | 99.0–99.8 | 87.0–89.0 | ISO 15023-1 |
| 4% solution viscosity (mPa·s, 20°C) | 58–68 | 26–32 | 44–52 | GB/T 12010.3 |
| Typical dissolution temperature (°C) | 88–95 | 85–92 | 45–55 | Visual clarity in stirred tank |
| Tensile strength (MPa, film, 23°C/50% RH) | 68–78 | 50–58 | 38–46 | ASTM D882 |
| Ash content (wt%, (L) variant) | ≤0.3 | ≤0.5 | ≤0.5 | ISO 3451-5 |
| Film oxygen barrier (cm³·25µm/(m²·day·atm)) at 0% RH | ≤0.5 | ≤0.6 | ≤1.2 | ASTM D3985 |
The data illustrate that the primary differentiation of PVA 26-99(L) lies in the confluence of high molecular weight and near-total hydrolysis, yielding the highest tensile modulus and lowest oxygen permeability among the common sizing and film grades, while demanding the most rigorous thermal pretreatment for dissolution and melt processing. The omission of significant residual acetate groups also renders this grade resistant to enzymatic degradation under ambient soil conditions—a property exploited in durable construction adhesives but problematic in short-life biodegradable packaging where PVA 26-88 or lower-DP fully hydrolysed grades degrade measurably faster.
In corrugated board manufacturing, a Steinemann glue kitchen preparing a 35% dry-content formula comprising 12 parts PVA 26-99(L), 80 parts native potato starch, 8 parts borax decahydrate, and 0.5 parts biocide yields a Stein-Hall viscosity of 42–48 s (Stein-Hall cup No. 2 at 40 °C). The presence of the fully hydrolysed PVA elevates the green bond on clay-coated Kraft liner to a pin adhesion value of 480–520 N/m (TAPPI T 821), whereas the same formulation substituting PVA with additional starch alone remains below 320 N/m. The critical operational constraint is the pot life at 40 °C, which declines from 6 h to approximately 3.5 h when the PVA degrades via alkaline chain scission in the presence of borax at pH 9.2–9.5. Stabilisation is achieved by adding 0.2 wt% sodium metabisulfite as an antioxidant and adjusting the borax addition timing to no earlier than 15 min before application. Compliance with indirect food contact requirements under FDA 21 CFR 176.170 and EU 10/2011 is confirmed for the dried adhesive film, provided the migration limit of 0.05 mg/kg for vinyl alcohol oligomers is not exceeded—a condition consistently met by this grade due to its high molecular weight restricting migration.
The product must never be combined with strong Lewis acids in aqueous solution: at pH values below 2.5, the acetal formation with glyoxal or glutaraldehyde proceeds uncontrollably, causing instantaneous gelation that clogs supply lines and doctor blade gaps. In paper surface sizing operations on a Valmet OptiSizer film press running at 1200 m/min, the recommended PVA:starch ratio is kept below 25:75 dry solids to avoid excessive shear at the blade metering zone; when the ratio reaches 30:70, the increased elastic component of the sizing liquor raises the hydraulic pressure on the metering element to 3.2–3.8 MPa, leading to streaking visible in the cross-direction under UV excitation. Formulators substituting PVA 26-99(L) into an existing cold-water-soluble grade should revalidate the in-line filtration strategy because the incidence of microgel-induced breaks on the size press increases threefold unless the starch jet cooker circuit is purged for 20 min at 105 °C during grade changeovers. In wood adhesive compounding with phenol-formaldehyde resole resins, the PVA acts as a rheology modifier; however, mixing must occur at temperatures under 50 °C to prevent premature condensation reactions between the PVA secondary hydroxyls and the methylol groups, which would elevate the minimum film-forming temperature of the hybrid adhesive beyond 25 °C and impair wet tack.
