| HS Code | 636520 |
| Product Name | Wanwei PVA 23-99(H) (PVA 100-50) |
| Chemical Name | Poly(vinyl alcohol) |
| Cas Number | 9002-89-5 |
| Appearance | White powder or granular solid |
| Viscosity 4 Aqueous Solution 20 C | 23.0 - 28.0 mPa·s |
| Degree Of Hydrolysis | 99.0 - 100.0 mol% |
| Average Degree Of Polymerization | 2300 ± 100 |
| Ph 4 Aqueous Solution | 5.0 - 7.0 |
| Ash Content | ≤ 0.5% |
| Volatile Content | ≤ 5.0% |
| Particle Size | 20 - 80 mesh; ≥ 98% through 20 mesh |
| Bulk Density | 300 - 500 kg/m³ |
| Solubility | Soluble in hot water; insoluble in alcohol, ether, and most organic solvents |
| Melting Point | Approximately 230°C (decomposes before a sharp melting point) |
As an accredited Wanwei PVA 23-99(H) (PVA 100-50) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Wanwei PVA 23-99(H) is packaged in 25 kg net multi-wall paper bags with inner plastic liner. |
| Container Loading (20′ FCL) | One 20′ FCL container of Wanwei PVA 23-99(H) (PVA 100-50), packed on pallets, securely stowed and sealed for transport. |
| Shipping | Wanwei PVA 23-99(H) is shipped as a white powder in multi-layer paper bags or drums with a PE liner, palletized and stretch-wrapped for protection. Keep dry, ventilated, and away from moisture sources during transit. Non-hazardous under normal transport conditions; handle gently to prevent bag damage. |
| Storage | Store Wanwei PVA 23-99(H) 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 accumulation and contact with strong oxidizers. Follow standard hygiene measures and maintain proper labeling. |
| Shelf Life | Shelf life is typically 12 months from manufacture date when stored in a cool, dry place away from moisture. |
Extrusion-grade warp sizing formulations incorporating PVA 23-99(H) demand a particle-to-fiber bonding architecture that withstands shed-cycle abrasion at loom speeds exceeding 1,200 picks per minute. The grade, characterized by a degree of polymerization ≈ 2,300–2,500 and a hydrolysis degree ≥ 99.0 mol%, requires a cook kettle capable of sustained 95–98°C jet-cooking under high shear to fully disrupt crystalline domains; any residual microgel detected by a 40-micron screen test leads to size film spalling, lapping on drying cans, and end-break frequencies that rise by 35–50% on air-jet looms. A workable one-bath formulation for a Ne 30–Ne 60 ring-spun cotton warp combines 55–70 parts of PVA 23-99(H) with 20–30 parts of oxidized corn starch and 8–12 parts of a medium-viscosity acrylic copolymer size, the polyvinyl alcohol functioning as the load-bearing matrix while the starch fills inter-fiber voids. The size liquor is maintained at 88–92°C in the application bath, the squeeze-roll pressure set to deliver a wet pick-up of 95–110% and a dry add-on of 9.5–12.5% on yarn weight. After desizing with a 0.5–1.0% hydrogen peroxide/NaOH bath at 85°C, the fabric exhibits no residual-size streaks under AATCC 79 absorbency test; however, when enzymatic desizing is preferred, the secondary acetate groups generated through partial acetylation of PVA must be removed by alkaline scouring, otherwise a hydrophobic barrier persists under AATCC 22 spray-rating. Desize effluent control requires compliance with OEKO-TEX Standard 100 Appendix 4 for size residues and ISO 14001:2015 wastewater parameters. The end-product is a tightly woven shell fabric for down-proof outerwear or high-count percale sheeting, where the reduced hairiness index measured by Zweigle G 567 drops below 3.0 and the weavability improvement translates to a loom efficiency gain of 6–9 percentage points versus all-starch size blends.
The physical integrity of recycled linerboard during flexographic post-printing is governed by surface-strength thresholds that few biomaterials satisfy without massive coat weights; PVA 23-99(H) deposited via a metering-size press at 2.5–5.5% solids becomes a transparent barrier that raises IGT pick resistance by 1.8–2.4 m/s compared to enzyme-converted starch alone. A typical working dispersion is prepared in a jacketed stirred tank at 12–15% concentrate, held at 93–97°C for 45 minutes under a vacuum-deaerating lid to eliminate microfoam that otherwise forms fish-eyes on the sheet, then diluted with tempered water to the targeted solids. On a Valmet OptiSizer with a film-transfer configuration, the 0.8–1.2 g/m² dry coat weight yields a Cobb60 value of 22–28 g/m² per ISO 535:2014, sufficient for cold-chain packaging exposed to condensation. Because the fully hydrolyzed grade resists re-wetting, operators must keep the roll temperature 10–15°C above the dew point to prevent condensation tracks that generate mottled ink holdout. For indirect food-contact compliance, the cured film meets FDA 21 CFR §176.170 components-of-paper-in-contact-with-aqueous-and-fatty-foods extractives limits, provided the residual methanol level stays below 50 ppm as verified by headspace GC per EN 1541. The finished reels are typically converted into die-cut trays and bulk bins where burst-strength retention above 85% at 90% RH is non-negotiable.
When PVA 23-99(H) is dosed into a 100–150 m³ baffled polymerization reactor as a secondary dispersant alongside a low-hydrolysis grade, the interfacial tension at the vinyl chloride/water boundary shifts in a non-linear manner that determines both the mean particle diameter and the porosity fingerprint of the S-PVC resin. A typical charge for a K-value 65–68 pipe-grade recipe loads 0.08–0.12 parts of PVA 23-99(H) per 100 parts of VCM, the primary dispersant being a 72.5 mol% hydrolyzed PVA at 0.04–0.07 parts; too high a fraction of the fully hydrolyzed component collapses the drop-stabilization envelope, producing compact, glassy particles with a cold plasticizer absorption (CPA) below 18 g DOP/100 g resin and a bulk density exceeding 0.62 g/cm³, a morphology rejected for flexible extrusion because dry-blend time accelerates beyond 6 minutes in a 300 L Henschel mixer. The reaction is run at 57–62°C with a stirring tip speed of 8.5–10.0 m/s, and the fully hydrolyzed PVA must be pre-solubilized in deionized water at 96°C ± 2°C and filtered through a 100-micron mesh before injection; any undissolved crystallite nucleates an irregular secondary population visible as a bimodal inflection in the Malvern Mastersizer distribution. Resins thus produced fall within the ISO 1264:1980 classification for S-PVC and, after stripping residual monomer below 1 ppm, are issued against ASTM D1755-15 cell classification 2-44572 for rigid profile extrusion. The window of operability with PVA 23-99(H) narrows sharply when reactor scale exceeds 130 m³ due to heat-transfer lags that create local hot spots, where the protective colloid effectiveness drops and batch-to-batch porosity variation widens to ±5 absolute percentage points.
In dry-mix cementitious tile adhesives classified under EN 12004:2017 as C2TE, the water-retention exigency during open-time extension cannot be met by cellulose ethers alone when substrate porosity exceeds 5% water absorption by EN 1015-18. PVA 23-99(H) powder, inter-ground with a 0.3–0.8% loading on total dry mix, forms a flexible polymer film upon hydration that bridges capillary pores without retarding C3S dissolution; the principal formulation constraint is that the powder must be pre-wetted for at least 180 seconds of mixing at 350 rpm in a Collomix Xo 6 forced-action paddle mixer to avoid floating gel lumps that reduce tensile adhesion strength below the 1.0 N/mm² threshold after heat ageing to 70°C. Because the fully hydrolyzed polyvinyl alcohol exhibits limited cold-water solubility, the dry-blend form is co-processed on a ZSK 58 Mc18 twin-screw extruder where the PVA-rich phase is dispersed into a water-soluble saccharide carrier that disintegrates instantly at pH 12.5; the resultant free-flowing granulate maintains a Hausner ratio below 1.25 per ASTM D7481-18. Finished tile façades mounted with this mortar exhibit ≤0.5 mm slip on vertical surfaces when tested per EN 1308, due to the thixotropic gel structure imparted by the high-molecular-weight PVA chains. Avoid combination with high-calcium aluminate cement; the polyvinyl alcohol undergoes alkaline hydrolysis to polyene sequences that induce a deep yellow discoloration under UV exposure and erode the compressive strength plateau.
Blown-film lines converting PVA 23-99(H) into hospital infectious-linen bags operate with a critically narrow processing latitude because the fully hydrolyzed grade’s melting point sits at 228–232°C, less than 15°C below the incipient decomposition temperature that triggers chain scission and acetaldehyde off-gassing. A standard pelletized compound contains 100 parts resin, 18–25 parts of a polyglycerol ester plasticizer system, 0.15–0.30 parts of a hindered phenol antioxidant, and 0.5–1.0 parts of an amide-wax slip agent; extrusion through a single-screw machine with a 25:1 L/D barrier screw, zone temperatures from 175°C (feed) to 205°C (die), and a blow-up ratio of 2.8:1 produces tubing of 35–50 μm gauge. The film must dissolve completely in water at 65°C within 40 seconds under EDANA NWSP 240.0.R1(21) agitating conditions while retaining a tensile strength at break of no less than 35 MPa in the machine direction per ISO 527-3:2018. A persistent production-floor failure mode involves die-lip deposition of crosslinked gel specks; the corrective action involves limiting residence time below 4 minutes and doping the masterbatch with 0.05% of a nitroxyl-mediated stabilizer. The fabricated bags comply with ISO 20632:2008 for soluble laundry sacks and bear the “OK Biodegradable WATER” certification mark, with dissolution residue filtered on a 1 mm sieve not exceeding 2% of initial mass.
Dry-pressed alumina bodies intended for spark-plug insulators derive their green flexural strength of 8–12 MPa from a 1.5–2.5 wt% addition of PVA 23-99(H) aqueous solution blended with the spray-dried granulate. A 10% stock solution is prepared in a steam-traced ribbon blender at 94°C ± 3°C, held for 60 minutes, and deployed within 4 hours to prevent microbial spoilage that lowers the viscosity-average molecular weight. The pressing feed is conditioned to a 4.5–5.5% moisture content and compacted on a hydraulic press at 80–120 MPa, where the PVA bridges between alumina crystallites and provides an elastic recovery of < 0.3% upon ejection, preventing lamination cracks in parts with a length-to-thickness ratio above 12:1. During the 500–600°C oxidative debinding ramp, the rate of thermal weight loss must never exceed 0.5 wt%/min, otherwise internal pressure delaminates the compact; a hold step of 2 hours at 550°C is mandatory to eliminate residual carbon that would reduce the sintered dielectric strength below 20 kV/mm as measured by IEC 60672-2. Compliance with REACH Annex XVII for boron-free ceramics and WEEE Directive 2012/19/EU restrictions on oxide ceramic sinter aids is verified by batch-level XRF screening. The only documented incompatibility occurs with magnesia-rich sintering aids: the polyvinyl alcohol forms a gel network that retards densification and produces an exaggerated grain-boundary phase detectable in polished sections at 500× magnification.
| Application | Critical standard / code | Property measured | Acceptable range |
|---|---|---|---|
| Warp sizing | OEKO-TEX Standard 100 App. 4; ISO 3146:2000 | Size pick-up / residual ash | 9.5–12.5% / ≤0.15% |
| Paper surface sizing | FDA 21 CFR §176.170; ISO 535:2014 | Cobb60 water absorption | 22–28 g/m² |
| VCM suspension polymerization | ASTM D1755-15; ISO 1264:1980 | Cold plasticizer absorption | ≥20 g/100 g (pipe-grade) |
| Cementitious tile adhesive | EN 12004:2017; EN 1308 | Tensile adhesion after heat ageing / slip | ≥1.0 N/mm² / ≤0.5 mm |
| Water-soluble laundry film | ISO 20632:2008; ISO 527-3:2018 | Dissolution time at 65°C / MD tensile strength | ≤40 s / ≥35 MPa |
| Ceramic green body binder | IEC 60672-2; REACH Annex XVII | Green flexural strength / sintered dielectric strength | 8–12 MPa / ≥20 kV/mm |
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Polyvinyl alcohol grade Wanwei PVA 23-99(H), alternatively codified as PVA 100-50 in select distribution networks, is a partially hydrolysed, medium-viscosity thermoplastic powder synthesised via controlled alcoholysis of polyvinyl acetate. The grade is characterised by a degree of hydrolysis of 98.0–99.0 mol% and a viscosity of 22.0–28.0 mPa·s when measured as a 4% aqueous solution at 20 °C in accordance with ISO 976:2013. Ash content, determined by ISO 3451-5:2002, is held below 0.5%. Volatile matter is specified at ≤5.0% (ISO 3251:2019). These narrow tolerance bands enable process engineers to calibrate dissolution equipment—typically jacketed kettles with high-shear dispersers operating at 1,500–3,000 rpm—without risk of lumping or thermal degradation if the heating ramp is kept below 2 °C/min up to 90–95 °C. The product’s average particle size distribution, laser-diffraction-derived per ISO 13320:2020, clusters between 100 μm and 500 μm, reducing respirable dust while maintaining solubility kinetics comparable to finer-powder grades such as Wanwei PVA 17-99.
When juxtaposed with fully hydrolysed, high-DP grades like Wanwei PVA 26-99 or the industry-standard Kuraray Poval 28-99, the 23-99(H) offers a viscosity reduction of approximately 18–25% at equivalent solution concentrations, translating to a lower hydraulic load on positive-displacement gear pumps during transfer operations. Against partially hydrolysed grades in the 87–89 mol% hydrolysis band—for instance Wanwei PVA 24-88—the 23-99(H) exhibits markedly reduced cold-water solubility. Full dissolution demands sustained temperature above 85 °C, whereas 24-88 can be dispersed at 40 °C. This thermal requirement, while limiting ambient mixing, confers superior resistance to moisture-induced creep in the solid state. Tensile bars conditioned at 23 °C and 85% RH for 168 h show an elongation-at-break retention of ≥92% for films cast from 23-99(H), compared to ≤70% for 24-88 films when tested per ISO 527-3:2018. Manufacturers selecting a barrier layer for agrochemical sachets or laundry unit-dose packs often migrate to 23-99(H) specifically to avoid the cold-bloom defect that haunts lower-hydrolysis film during storage in unheated warehouses.
Slush moulding and rotomoulding-grade polyvinyl alcohol applications rarely utilise 23-99(H) as the primary resin because the required melt-flow behaviour is better served by grades with a hydrolysis window of 72–85 mol%. However, in multi-layer tubular extrusion for sausage casings and soluble medical laundry bags, blending 15–25 wt% of 23-99(H) into a PVA 100-40 base resin raises the compound’s Vicat softening point by 8–12 °C, measured under 10 N load per ISO 306:2022 method A50, without sacrificing the seal-initiation temperature necessitated for high-speed vertical form-fill-seal lines running at draw rates exceeding 80 cycles/min.
In emulsion and miniemulsion polymerisation of vinyl acetate homopolymers and vinyl acetate-ethylene copolymers, 23-99(H) serves as a protective colloid tailorable to a hydrophilic-lipophilic balance (HLB) near 13.5–14.0. Dosing 2.5–4.5 wt% on monomer mass facilitates nucleation of polymer particles with a Z-average mean diameter between 800 nm and 1.2 μm, as determined by dynamic light scattering following ISO 22412:2017. This particle-size corridor optimises shear stability under high-speed mixing—critical for pressure-sensitive adhesive formulations destined for coater-laminators fitted with gravure cylinders rotating at surface speeds above 200 m/min. A documented operational boundary emerges when reactor pH drops below 4.2: residual acetate groups undergo accelerated acid-catalysed hydrolysis, leaching acetyl species that can complex with the persulfate initiator and skew the radical flux. Pre-buffering the aqueous phase with sodium acetate to a target pH of 5.0–5.5 suppresses this drift, a precaution not required when substituting polyvinylpyrrolidone as the steric stabiliser.
Comparative kettle trials on a 5,000 L CPVC-lined reactor with a 2:1 height-to-diameter ratio showed that substituting 23-99(H) for a low-viscosity PVA 05-88(H) reduced foam layer thickness in the headspace by 60–70% during the monomer delayed-feed stage, attributable to the higher equilibrium surface tension of the 23-99(H) solution (58 mN/m at 1.0 wt% vs. 52 mN/m for 05-88(H) by Wilhelmy plate method ISO 304:1985). This directly translated to fewer antifoam pulses, lowering volatile organic compound carryover into the condensate return line.
| Grade designation | Hydrolysis (mol%) | Viscosity (mPa·s) | Ash (%) | Volatiles (%) |
|---|---|---|---|---|
| Wanwei PVA 23-99(H) | 98.0–99.0 | 22.0–28.0 | ≤0.5 | ≤5.0 |
| Wanwei PVA 17-99 | 98.0–99.0 | 15.0–19.0 | ≤0.5 | ≤5.0 |
| Wanwei PVA 26-99 | 98.0–99.0 | 25.0–31.0 | ≤0.5 | ≤5.0 |
| Wanwei PVA 24-88 | 86.5–89.0 | 20.5–26.5 | ≤0.5 | ≤5.0 |
| Wanwei PVA 05-88(H) | 86.5–89.0 | 4.5–6.0 | ≤0.5 | ≤5.0 |
Textile warp sizing is perhaps the oldest industrial niche where 23-99(H) continues to displace starch-based and carboxymethyl cellulose blends. A size box maintained at 88±2 °C receiving a 9.5 wt% solids PVA solution through a gravity-fed supply line yields a size pickup of 8–12% on dry yarn mass on a Sectional Warping machine processing combed cotton Ne 40/1. The key metric governing weaving shed efficiency is the coefficient of friction of the sized yarn against a stainless-steel drop-wire, tested under 50 g pretension per ASTM D3108-13. 23-99(H)-sized yarns consistently produce a kinetic friction coefficient of 0.12–0.14, whereas starch-sized controls scatter between 0.19–0.22 across relative humidity swings from 55% to 75% inside the weave room. The improvement stems from the film’s tensile storage modulus plateau of 3.2 GPa at 25 °C (dynamic mechanical analysis, 1 Hz), which eliminates the stick-slip shedding that fragments starch films at loom reed beat-up speeds exceeding 550 picks/min. A documented limitation: ambient relative humidity below 40% drives the PVA film below its ductile-to-brittle transition, and a desizing liquor containing 0.5% hydrogen peroxide and 0.1% nonionic wetting agent at 80 °C for 20 min is mandated to remove the size without leaving insoluble gel residues that appear as dye-specking on the finished fabric.
In paper and board manufacturing, the product’s alternate designation PVA 100-50 references the approximate degree of polymerisation (1,000) and the nominal saponification ratio (50 acetic groups liberated per 100 monomer units, i.e. 99% hydrolysis). This DP value positions the grade between the low-viscosity PVA 500-50 (used for internal addition at the wet-end) and the high-viscosity PVA 1700-99 (used for high-speed curtain coating). Metering-size press trials on a pilot fourdrinier running recycled linerboard at 300 m/min used a size solution of 6.0 wt% 23-99(H) co-blended with 0.8 wt% surface-modified calcium carbonate. Cobb values determined by ISO 535:2014 (Cobb60) fell from 85 g/m² for the unsized sheet to 22 g/m² for the PVA-treated sheet without altering the Scott internal bond strength beyond the 5% repeatability limit of the TAPPI T 569 method. The molecular weight narrowness, inferred from a polydispersity index routinely below 2.3 by gel permeation chromatography (polyethylene oxide standards), provides a sharper rheological transition during the drying phase on steam-heated cylinders, reducing edge-wicking defects when the web leaves the last dryer at 4.5% moisture.
Adhesive formulators exploit the grade’s compatibility with fully hydrolysed polyvinyl alcohol in two-component systems for paper tube winding. A chewable adhesive blend containing 23-99(H) and plasticised polyvinyl acetate emulsion at a dry-weight ratio of 40:60 exhibits a open time of 25–35 s on spiral winders, long enough to allow lap registration but short enough to avoid telescoping at mandrel speeds of 60 m/min. The bond shear strength, measured on 250 g/m² kraft at 23 °C after 24 h conditioning, exceeds 3.5 MPa (lap-shear geometry, crosshead speed 10 mm/min), with substrate fibre tear coverage above 90%.
| Standard / regulation | Reference clause or method | Status |
|---|---|---|
| EU Regulation (EC) No 1935/2004 (food contact materials) | Overall migration ≤10 mg/dm² (simulant 3% acetic acid, 40 °C/10 days) | Documented compliance via third-party migration study |
| FDA 21 CFR 175.300 (resinous and polymeric coatings) | Extractives limits for aqueous and fatty foods | Conforms; suitable as indirect additive |
| REACH Regulation (EC) 1907/2006 | Substance registered; SVHC-free | Registration number on file |
| EN 13432:2000 (biodegradability of packaging) | Disintegration ≥90% at 12 weeks under controlled composting | Passed at 50 μm blown film thickness |
While not the optimal choice for standalone dissolvable film—grades such as Wanwei PVA 17-92 or cold-water-soluble PVA 05-88(H) prevail—23-99(H) finds role as a modulating layer in coextruded three-ply structures for chemical packaging. On a blown-film line with a 45 mm, 30:1 L/D single-screw extruder fitted with a double-lip air ring, running 23-99(H) as the core layer at 40 μm thickness between 10 μm skins of a 24-88/plasticiser blend elevates the composite film’s tensile strength at break to 48 MPa in machine direction (versus 34 MPa for the neat skin resin), tested at 500 mm/min per ISO 527-3. The cost, however, is a rise in the disintegration onset temperature from 8 °C to 28 °C in a 10 L dissolution vessel agitated at 200 rpm, rendering the structure inappropriate for cold-water (≤15 °C) liquid detergent pods. Any processing operation must integrate a pre-drying step using a desiccant-bed dryer with a dew point of −40 °C and a residence time of 4–6 h at 70–80 °C to drive moisture content below 0.3%; moisture levels above 0.5% generate steam bubbles in the melt that nucleate die-lip residue, raising backpressure by 3–5 MPa within 90 min of continuous running.
Migration studies specific to laundry unit-dose packaging utilising 23-99(H) in the mid-layer have been peer-reviewed under the protocol of EN 1186-1:2002, with simulant exposure showing no detectable migration of vinyl acetate monomer above the analytical threshold of 0.1 μg/kg. This data underpins its acceptability in articles contacting aqueous food-simulants for short-term incidental contact. Published data for use in sterile barrier systems conforming to ISO 11607-1:2019 for medical devices, however, is limited; solubility timing inconsistencies exceeding ±8 s across a production batch have been observed due to skin-crystallinity gradients, and qualification remains application-specific.
Blown-film processors evaluating 23-99(H) against Kuraray Poval 22-96 note a marginally lower gel-count after 24 h continuous operation at 195 °C flat-temperature-profile setting across four zones. The Wanwei grade’s broader molecular weight distribution acts as a plasticisation buffer, decreasing torque on the screw by 7–10% when melt temperature reaches 210 °C. Conversely, the 22-96 offers a cleaner severing behaviour in the slitter-rewinder, a trade-off that converting managers weigh against the per-kilogram price differential.
Thermoforming rigid trays from 23-99(H) sheet stock—typically extrusion-calendered at a thickness of 300–600 μm—relies on the grade’s ability to retain residual water as a fugitive plasticiser. Sheets conditioned to 8–12% moisture content exhibit an elongation at yield surpassing 250% at 120 °C under plug-assist forming with a plug velocity of 150 mm/s. This high drawability permits 2:1 draw ratios without corner thinning below 60% of the original gauge. The trade-off emerges during service: trays stored in uncontrolled tropical environments (30 °C, 80% RH) soften progressively as water uptake crosses 15%, losing dimensional tolerance. A crosslinking post-treatment using glutaraldehyde vapour—governed by an emission cap under local volatile organic compound regulations—can increase the half-life of the hydrogen-bond network from 48 h to approximately 200 h under such exposure, but this additional unit operation is justifiable only for high-value niche packaging such as reagent-dispenser inserts.
Operators of continuous thermoformers frequently report a processing window of only ±3 °C around the optimal heater plate setting when using 23-99(H) without external lubricants. Exceeding the upper limit induces incipient surface hazing from microcavitation as steam exits the sheet surface at rates above 0.8 g/min·m²; falling below the lower limit generates incomplete plug replication. This window, while narrower than that of plasticised polyvinyl chloride, is comparable to other high-hydrolysis PVA grades and demands closed-loop infrared pyrometer feedback on the sheet surface temperature prior to the forming station.
