| HS Code | 503422 |
| Product Designation | Wanwei PVA 17-92(L) (PVA 092-20) |
| Appearance | white granular powder |
| Cas Number | 9002-89-5 |
| Chemical Formula | (C2H4O)n |
| Average Molecular Weight | approximately 80,000 |
| Degree Of Polymerization | 1700 |
| Degree Of Hydrolysis | 92.0 ± 1.0 mol% |
| Viscosity 4pct Aqueous 20c | 20.0-30.0 mPa·s |
| Ph 4pct Aqueous Solution | 5.0-7.0 |
| Volatile Matter | ≤5.0% |
| Ash Content | ≤0.5% |
| Bulk Density | 0.4-0.6 g/cm³ |
| Melting Point | 180-190°C |
| Water Solubility | soluble in cold and hot water; insoluble in common organic solvents |
As an accredited Wanwei PVA 17-92(L) (PVA 092-20) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Wanwei PVA 17-92(L) is supplied in 25 kg multi-wall paper bags with inner polyethylene liner, palletized and shrink-wrapped. |
| Container Loading (20′ FCL) | 20′ FCL loaded with Wanwei PVA 17-92(L) (PVA 092-20), palletized bagged chemical cargo, securely stowed and lashed to prevent movement during transit. |
| Shipping | Wanwei PVA 17-92(L) is shipped in sealed, moisture-proof bags or drums to prevent clumping and contamination. Transport in dry, well-ventilated containers, avoiding heat, humidity, and direct sunlight. Handle gently to avoid dust generation. Ensure compatibility with local shipping regulations and label accordingly. |
| Storage | Store Wanwei PVA 17-92(L) in a cool, dry, well-ventilated area, away from direct sunlight, heat, and ignition sources. Keep the original container tightly sealed to prevent moisture absorption and contamination. Avoid dust generation; keep away from strong oxidizers. Maintain moderate humidity and stable temperatures to preserve quality and prevent caking or degradation. |
| Shelf Life | Shelf life is 12 months from manufacture when stored sealed, cool, and dry. |
In the precision-controlled environment of an air-jet loom weaving 40s Ne cotton-polyester yarns at 680 picks per minute, the cohesive strength and elongation-at-break of the size film deposited within the yarn body directly govern warp stoppage rates and beam weavability. Wanwei PVA 17-92(L), a partially hydrolyzed polyvinyl alcohol characterized by a hydrolysis degree of 92.0–92.8 mol% and a 4% aqueous solution viscosity of 20.0–26.0 mPa·s (measured per DIN 53015 at 20°C), is integrated into size formulations for ring-spun and open-end yarns at a dry solids addition rate of 8.5–12.0 wt% relative to the total size liquor. The size preparation sequence follows a two-stage atmospheric cooking process in a modified double-jacketed cooker equipped with a high-shear disperger (tip speed ≥ 18 m/s) : cold-water swelling at 25–30°C for 20 min, followed by programmed heating to 94–96°C and a hold time of 45–60 min under continuous slow agitation to prevent microgel formation. In the sizing zone of a multi-cylinder sizing machine, the size liquor is maintained at 88–92°C within the reservoir, and the application is performed via a single or double dip-squeeze configuration with squeeze roller pressures calibrated to 1.2–2.0 bar. Residual moisture on the warp sheet at the main drying cylinder inlet is constrained to 32–36% to avoid excessive drying energy while preventing fiber swelling-related loss of film integrity. The four-cylinder cascade drying profile is ramped from 105°C to 125°C with a final moisture content of 6.0–7.5% in the sized beam. End-use compliance draws on the eco-toxicological thresholds of OEKO-TEX Standard 100 Annex 4 for restricted substances in textiles; no formaldehyde or ethylene urea residues are introduced by the PVOH macromolecule. The sized warp is converted into plain-weave and twill workwear fabrics, high-density bed-linen sheeting, and down-proof outerwear shells. An operational boundary of note: at relative humidity exceeding 68% in the weaving shed, the PVA film softens sufficiently to reduce its glass transition temperature from approximately 48°C to 32°C, resulting in increased sticking frequency on the reed and heald wires unless the ambient air is dehumidified to maintain a 55±5% RH equilibrium.
For solid bleached sulphate board destined for indirect food contact applications, the application of a pure PVOH surface size at the film press closes surface micropores and delivers a measurable reduction in the Cobb60 value when applied at a coat weight of 0.8–1.5 g/m² per side. Wanwei PVA 17-92(L) is cooked into a 1.5–2.5% aqueous solution, filtered through a 100 µm bag filter, and applied on a metered size press operating at 800–1100 m/min with a blade loading pressure of 12–18 kN/m. The base paper sheet moisture before sizing is held at 3.0–4.0% to maximize film pickup uniformity. Post-sizing drying by infrared plus air-flotation dryers brings the sheet surface temperature to 95–100°C for film formation within a residence time of 1.5–2.0 s. Target Cobb60 values for the coated board fall below 22 g/m² (ISO 535:2023), and the system passes the extractives limits of 21 CFR 176.170 Table 1 for food-contact paper components. Terminal products include frozen food trays, detergent cartons with water-based flexo printing, and pharmaceutical secondary packaging. Processors are cautioned that calcium ion concentrations above 180 ppm in the dilution water will complex with residual acetate groups and generate a brittle film that fractures along fold lines during converting.
In paper tube winding and folded carton side-seam gluing lines running at linear velocities above 65 m/min, the substitution of traditional acid-modified starch or dextrin with a 12–16% solids Wanwei PVA 17-92(L) solution modifies the setting mechanism from evaporative water loss to critical gelation triggered by a drop in temperature below 38°C. Formulating the adhesive with 3.0–5.0 wt% plasticizer (glycerol or sorbitol, based on dry PVOH mass) extends the open time to 8–11 s under controlled application via a 0.2–0.4 mm slot-die nozzle at 55–60°C. The storage modulus of the dried film exceeds 2.8 GPa (DMTA at 25°C, 1 Hz), contributing to burst-strength retention in spiral-wound paper cores subjected to winding tension gradients of 1.5–3.0 N/mm. Conformity to the mechanical safety and restrictive substances protocols of EN 71-3:2019+A1:2021 for migration of certain elements enables use in toy packaging; grades formulated without boric acid pass the toxicity benchmarks of ASTM D4236. Outputs encompass laminated spiral cores for adhesive tape and release-liner rolls, multi-wall paper sacks for cement and dry chemicals, and rigid paperboard education kits. A process incompatibility must be observed: the addition of sodium tetraborate (borax) at concentrations exceeding 0.15% of the wet adhesive weight initiates an instantaneous PVA-borate di-diol crosslink that raises the apparent viscosity beyond the pumpability limit of pneumatic positive-displacement dispensing systems, leading to nozzle starvation and intermittent bead voids on the substrate.
In dry-mix formulations intended for tile adhesives of the C2 classification per EN 12004:2017, the role of polyvinyl alcohol is typically associated with re-dispersible polymer powders, yet a direct addition of fine-milled Wanwei PVA 17-92(L) to the cement-sand-filler premix as a secondary rheology modifier and early-age crack arrestor is deployed at a dosage of 0.25–0.60% of the total dry blend mass. The PVOH powder, sieved to <120 µm and pre-dried to a residual moisture below 0.8%, is dry-blended with Portland cement CEM I 42.5 N, silica sand (0.1–0.6 mm), and cellulose ether in a gravity-free-fall mixer for 180 s. Upon wet mixing at a water-to-dry-mix ratio of 0.22–0.26, the polymer dissolves gradually over a period of 4–7 min under continuous stirring, building a transient viscous gel that extends the pot life by 8–12 min beyond the cellulose-ether-only reference. Tensile adhesion strength after 28 d of standard water immersion (EN 1348) increases from 0.85 MPa to 1.05 MPa without reducing the open time below 20 min. Compliance with low volatile organic compound emissions under the AgBB testing scheme is achieved; formulations fall below the 30 µg/m³ total VOC threshold after 28 d. The direct addition method serves the production of polymer-modified tile grouts, waterproofing slurries for balcony substrates, and repair mortars for concrete spall repair. A failure mode observed at scale involves the formation of polymer-rich surface skins on the cured adhesive when the ambient temperature during application exceeds 32°C and relative humidity falls below 40%; this skin impedes wetting of the tile back and produces a characteristic bond-strength gradient of up to 40% reduction between the center and edges of large-format porcelain tiles (≥60×60 cm).
Protective colloid selection in the semi-batch emulsion polymerization of vinyl acetate-ethylene (VAE) dispersions dictates both the reactor fouling tendency and the resultant film’s tensile shear performance in wood-glue joints. Wanwei PVA 17-92(L), processed as a 10–12% solution at 85–90°C and cooled to 60°C before charging, functions as the primary protective colloid at a loading of 5.5–7.0% of total monomer mass. The polymerization is conducted in a jacketed 2.5 m³ glass-lined reactor equipped with a three-anchor 45°-pitch agitator operating at 80–100 rpm; the initial charge contains 18–22% of the monomer and the full amount of dissolved PVOH. After the vinyl acetate feed is initiated at a constant rate over 3.5–4.5 h under an ethylene partial pressure of 28–42 bar, the evolving particle population is stabilized against catastrophic aggregation by the PVOH interfacial layer. The minimum gel content of the final latex, determined as residue on a 40 µm sieve after vacuum filtration, must remain below 0.05% to permit use in transfer-coating lines. Film formation on a chill roll at 2°C yields a heat-seal activation temperature of 68–74°C for packaging applications. The polymerized dispersion meets the extractive provisions of 21 CFR 175.105 for indirect food additives in pressure-sensitive labels; additionally, the finished adhesive qualifies for the durability class D3 per EN 204:2016 (non-structural interior use with frequent short-term water exposure) when compounded with 1.5–2.0% defoamer and 2.5–3.0% plasticizer. Terminal downstream articles include bookbinding PUR/PVOH hybrid adhesives, clear-on-clear label stock for PET bottles, and heat-sealable lidding films for dairy cups. Process engineers are warned that a reactor turnaround that fails to remove PVOH precipitate from the agitator shaft seal faces will catalyze a self-accelerating accumulation of burnt-on residue in the presence of residual vinyl acetate monomer, eventually constricting the ethylene mass-transfer efficiency and shifting the copolymer composition by 4–7% ethylene content in the subsequent batch.
In the uniaxial die pressing of high-purity (>99.6% Al₂O₃) substrates for thick-film hybrid circuits, the organic binder must satisfy two contradictory criteria: sufficient green strength to survive robotic green-body handling at a bending moment of 0.25–0.40 N·m, and a thermogravimetric ash residue below 0.02% after a 2°C/min ramp to 450°C followed by a soak at 650°C. Wanwei PVA 17-92(L) is introduced as a 8.0–10.0 wt% aqueous solution into a zirconia-lined ball-milling step with the alumina feedstock (D₅₀ ≈ 0.8 µm) and an ammonium polyacrylate dispersant. The effective binder dry content relative to powder is adjusted to 0.8–1.3% by weight, determined by the surface-area-to-volume ratio of the spray-dried granules targeting a D₅₀ of 90–120 µm. Granule production via a co-current spray dryer employs an inlet temperature of 210–225°C and an outlet of 95–105°C, generating spherical agglomerates with a moisture content of 1.2–1.8% ready for pressing. The pressing operation loads the granules into a multi-cavity cemented tungsten carbide tool set at a filling depth of 6–8 mm and a compaction pressure of 90–110 MPa. After binder burnout in an electrically heated tunnel kiln with an oxidizing atmosphere, the substrates are finished to a 0.635 mm thickness and a camber of less than 0.05 µm/mm. Conformance to the surface-discharge and dielectric-strength specifications of IEC 60672-2:1999 relies on the complete elimination of any char residue that would otherwise create conductive pathways between screen-printed silver-palladium conductors. Finished product types include LED module carriers, laser scribed break-plate substrates, and planar gas-discharge display backplanes. Granule storage conditions must be controlled: exposure to relative humidity above 55% for periods exceeding 6 h increases the equilibrium moisture of the PVA binder phase beyond 2.5%, a level at which the onset pressure for lamination cracks during compaction drops from a safe margin of 120 MPa to below 95 MPa.
| Application Scenario | Typical PVOH Solids Addition | Critical Compliance Standard | Predominant Film Mechanism |
|---|---|---|---|
| Warp Sizing (Cotton-Polyester) | 8.5–12.0 wt% of size liquor | OEKO-TEX Standard 100 Appendix 4 | Cohesive film bridging under cyclic elongation |
| Paperboard Surface Sizing | 1.5–2.5% solution concentration | ISO 535:2023 Cobb60 | Pore-sealing monolayer with controlled surface energy |
| Adhesives for Paper Converting | 12–16% solids | EN 71-3:2019+A1:2021 | Thermo-reversible gelation above minimum gel temp. |
| Dry-Mix Mortar | 0.25–0.60% of dry blend | EN 12004:2017 (C2 classification) | Gradual dissolution and early-age crack suppression |
| VAE Protective Colloid | 5.5–7.0% of monomer mass | 21 CFR 175.105, EN 204:2016 D3 | Interfacial steric stabilization and latex particle size control |
| Technical Ceramic Binder | 0.8–1.3% dry basis on powder | IEC 60672-2:1999 | Green-body interlock and complete pyrolytic decomposition |
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The Wanwei PVA 17-92(L) grade, alternatively designated PVA 092-20, is a partially hydrolysed polyvinyl alcohol resin with a nominal degree of hydrolysis of 92.0 ± 1.0 mol% and a viscosity of a 4% aqueous solution at 20°C ranging from 20.0 to 26.0 mPa·s. The suffix “L” denotes a low-ash, low-methanol variant produced through intensified washing and alcoholysis control; residual methanol content is maintained below 1.0 wt% and sulphated ash typically below 0.2 wt%, making the grade suitable for indirect food-contact adhesives governed by FDA 21 CFR 175.105 and EU Regulation (EC) No 1935/2004. The primary chain architecture—a vinyl acetate-vinyl alcohol copolymer with approximately 8 mol% residual acetate groups—delivers a characteristic balance of film strength, water redispersibility, and thermoplastic processability that differentiates it from both fully hydrolysed homopolymers and more highly substituted copolymers.
| Property | Typical Value | Test Method |
|---|---|---|
| Degree of hydrolysis | 91.5–93.0 mol% | ISO 15023-1:2017 (back-titration) |
| Viscosity (4% aq., 20°C) | 20.0–26.0 mPa·s | ISO 3104:2023, Brookfield LVDV |
| Degree of polymerization (DP) | 1650–1850 | JIS K6726 (viscometric) |
| Volatile matter | ≤ 5.0% | ISO 3251:2019 (105°C, 2 h) |
| Ash content (sulphated) | ≤ 0.2% | ISO 3451-1:2019 |
| Methanol | ≤ 1.0% | Headspace GC-FID, internal method |
| pH (4% solution) | 5.0–7.0 | ISO 976:2013 |
| Bulk density | 0.45–0.60 g/cm³ | ISO 60:2023 |
In textile warp sizing, the 92 mol% hydrolysis level reduces the minimum dissolution temperature to 88–92°C, compared with the 95–100°C demanded by fully hydrolysed 99 mol% grades, enabling direct use in closed, jacketed cooking kettles without the need for a high-pressure steam sparge. On modern sectional warping lines operating at 400–600 m/min, the size film formed on polyester-cotton blends exhibits an adhesion force to polyester of 6.2–7.8 N/2.5 cm when measured by a modified ASTM D6862-11 peel test, and desizing efficiency exceeds 98% using a sequential hot-water (80°C) / amylase-enzyme scouring procedure, as monitored by spectrophotometric detection of residual iodine complex at 690 nm. Fully hydrolysed PVA, by contrast, requires oxidative chemistry to achieve comparable desizing completeness, increasing BOD loading in effluent streams by 35–50%. The presence of 8 mol% acetate groups also confers sufficient thermoplastic character to permit plasticiser-free cohesive bonding of the size film on high-speed looms, reducing weft stops and shed contamination relative to starch- or CMC-based formulations.
In paper coating and surface sizing, the same hydroxyl-acetate balance widens the operating window for blade or rod coaters running LWC and ULWC grades. Pilot trials on a 14 m dilution-type metering size press with a web speed of 1200 m/min demonstrated that a 5.0 wt% PVA 17-92(L) solution containing 0.3 wt% glyoxal crosslinker produced a dry coat weight of 1.2–1.4 g/m² without the foam generation typical of fully hydrolysed PVA, attributable to the slightly increased surface tension dynamics measured by pendant drop analysis.
When humidity exceeds 60% RH during storage or pneumatic conveying, the granules must undergo pre-drying in a dehumidified hopper dryer at 60°C for 2–3 hours to bring residual moisture below 0.3 wt%. On a blown film line equipped with a 60 mm single-screw extruder (L/D 30) and a spiral mandrel die, failure to pre-dry resulted in a 0.8 MPa increase in melt pressure at the breaker plate and periodic bubble instability due to vapour nucleation, an effect not observed with the grade’s low-methanol variant. In cast-film slot-die coating for water-soluble detergent pouches, gel particle defects above 120 µm were eliminated when dissolution temperature was held strictly within the 88–92°C band and the stirred tank was fitted with a 60-mesh inline screen before the filter cartridge.
PVA 17-92(L) is prone to premature gelation when combined with primary amine-functional crosslinkers in aqueous systems at pH values above 7.5. In one adhesive compounding run, the addition of 2.0 wt% m-phenylenediamine at 75°C raised the dynamic viscosity from 1.8 Pa·s to beyond the measurable limit within 40 seconds, forming an irreversible clotted mass that blocked the positive displacement pump. This behaviour is attributed to nucleophilic attack of amine groups on residual acetate moieties, releasing methanol and forming amide bridges that accelerate network build-up. Consequently, crosslinking strategies for this grade rely on aldehyde donors (glyoxal, glutaraldehyde) or water-dispersible polyisocyanates blocked with caprolactam; the latter require a deblocking temperature above 140°C, aligning with the melt phase in extrusion lamination. In paper sizing operations, glyoxal is introduced inline via a static mixer just upstream of the coat weight blade, with a pot life of 4–6 hours at 25°C when the pH is buffered to 4.5 using a phosphate-citrate buffer system.
The following table contrasts key processing characteristics of PVA 17-92(L) with a fully hydrolysed counterpart (PVA 17-99, ≥99 mol% hydrolysis) and a lower-hydrolysis grade (PVA 17-88, 88 mol%). The data were generated from solutions prepared with identical raw water hardness (120 mg/L CaCO₃) and heating ramp profiles, and from film specimens cast under identical draw-down conditions and conditioned at 23°C / 50% RH for 48 h.
| Parameter | PVA 17-88 | PVA 17-92(L) | PVA 17-99 | Test method |
|---|---|---|---|---|
| Min. dissolution temp. (clear solution) | 72–78°C | 88–92°C | 95–100°C | Visual, 1°C/min ramp |
| Solution viscosity (4%, 20°C) | 20–26 mPa·s | 20–26 mPa·s | 28–35 mPa·s | ISO 3104:2023 |
| Tensile strength (film, 25 µm) | 38–45 MPa | 50–58 MPa | 62–72 MPa | ISO 527-3:2018 |
| Elongation at break | 180–220% | 150–190% | 90–120% | ISO 527-3:2018 |
| Melting endotherm peak (DSC, 10°C/min) | 182–188°C | 192–198°C | 224–230°C | ISO 11357-3:2018 |
| Apparent melt viscosity at 210°C, 100 s⁻¹ | 380–420 Pa·s | 520–580 Pa·s | Not processable without plasticiser | Capillary rheometer, L/D 30 |
| Film cold-water (25°C) disintegration time | 45–60 s | 120–150 s | Partial only; >300 s | Modified ISO 14087:2022 |
| Adhesion to viscose rayon (size test) | 5.2 N/2.5 cm | 7.0 N/2.5 cm | 7.8 N/2.5 cm | ASTM D6862-11 |
The data illustrate why 17-92(L) is preferentially specified where processability in conventional melt extrusion (L/D ≥ 30 twin-screw, screw speed 200–250 rpm, zone temperatures 180–210°C) must be preserved alongside solubility adequate for downstream removal, and why it occupies a distinct extrusion compounding space: it does not suffer the acetic acid odour and stringiness of 88-mol% grades when processed near the melt ceiling, nor does it demand the high-temperature dissolution infrastructure of 99-mol% grades. In co-extruded barrier structures where a PVA interlayer is sandwiched between polyolefin tie layers, 17-92(L) can be processed without the addition of polyol plasticisers up to 15 phr, provided the screw profile incorporates a 30:1 compression ratio mixing section with Maddock elements to dissipate 1.2–1.4 kWh/kg of specific energy input.
Published data for hot-melt adhesive compounding of 17-92(L) with polyamides to improve open time remains limited; however, in-house trials on a ZSE 27 MAXX co-rotating twin-screw extruder with a strand pelletising take-off showed that a 20 wt% addition of 17-92(L) to a dimer-acid-based copolyamide raised the melt flow index from 8 g/10 min to 15 g/10 min (160°C, 2.16 kg, ISO 1133-1:2022) and reduced the setting time by 3 s, without compromising T-peel adhesion to corona-treated PET.
A distinction of the “L” designation is the reduced tendency to generate insoluble microgel residue in standing solutions. Several batches stored as 8% aqueous stock at 25°C for 72 hours maintained a filterability ratio (passage through a 20 µm absolute-rated depth filter at constant pressure) above 95%, while a comparable non-L 17-92 grade dropped to 82% under identical conditions, suggesting that catalyst residues and low-molecular-weight oligomers have been depleted enough to suit precision coating applications such as photoresist support films.
