| HS Code | 565480 |
| Product Name | KURARAY POVAL 11-98 |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White granular powder |
| Degree Of Hydrolysis | 98.0 - 99.0 mol% |
| Viscosity 4 Percent Solution 20c | 10.0 - 12.0 mPa·s |
| Ph 4 Percent Solution | 5.0 - 7.0 |
| Volatile Content | <= 5.0 wt% |
| Ash Content | <= 0.5 wt% |
| Average Polymerization Degree | ~1100 |
| Molecular Weight | ~48000 g/mol |
| Density | 1.27 g/cm3 |
| Solubility | Soluble in hot water; insoluble in organic solvents |
As an accredited KURARAY POVAL 11-98 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | KURARAY POVAL 11-98 is supplied in 25 kg multi-layer paper bags with polyethylene liner for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL shipment of KURARAY POVAL 11-98 polyvinyl alcohol, packed in 25 kg bags on pallets, securely loaded for transport. |
| Shipping | KURARAY POVAL 11-98 is a polyvinyl alcohol powder shipped in sealed multi-layer bags or drums to protect against moisture. Transport is typically non-hazardous, but keep dry, avoid dust accumulation, and store in a cool, ventilated area during freight handling. |
| Storage | Store KURARAY POVAL 11-98 in a cool, dry, well-ventilated area in its original, tightly sealed container. Protect from moisture, humidity, and direct sunlight. Keep away from heat, open flames, and incompatible materials. Avoid generating dust; use dust-control measures. Reseal packaging immediately after each use to prevent contamination and maintain product quality. |
| Shelf Life | Store in original container in a dry, cool place. Shelf life is typically 2 years from manufacture date when unopened. |
KURARAY POVAL 11-98 functions as the primary film former in warp sizing formulations for ring-spun combed cotton and blended cotton–polyester yarns in the 20–40 tex fineness range. The grade is selected because its 98.0–99.0 mol% hydrolysis and 11.0–14.0 mPa·s viscosity for a 4 wt% aqueous solution at 20 °C produce a cohesive, abrasion-resistant size film after drying. In typical sizing recipes, the total size bath solids are maintained at 5.5–8.5 wt%, with POVAL 11-98 contributing 30–50 wt% of dry size solids and modified starch supplying the balance. Dry size add-on on the yarn is controlled at 8–12% by mass after squeeze-roll consolidation. The size is cooked in a jacketed high-shear cooker at 90–95 °C for 30–45 min with impeller speeds of 900–1200 rpm, then held in the service tank at 65–75 °C. On the sizing machine, the paste is applied through a double-roll squeeze box at nip pressure of 20–30 kN per metre of roll face, followed by multi-cylinder drying where the first cylinder surface is held below 110 °C and final yarn moisture is controlled to 2–4% for cotton-rich warps. The terminal output is a sized warp beam for air-jet or rapier weaving of apparel, workwear, and bedding fabrics. Compliance for the size formulation is assessed against brand mRSL and ZDHC MRSL 2.0 requirements, with final yarn tensile properties verified by ASTM D2256/D2256M-21. When sodium tetraborate is used as a controlled crosslinker, the addition sequence must prevent direct contact between concentrated POVAL 11-98 solution and borate ions; gelation is observed when tetraborate decahydrate exceeds 0.1–0.2 wt% of total size liquor at pH 8.0–9.5. Batch viscosity is checked with a Brookfield LVF viscometer, spindle No. 2 at 12 rpm; a drift greater than 15% within 2 h indicates premature gelation or incomplete dissolution.
In polyvinyl acetate emulsion polymerisation, KURARAY POVAL 11-98 is introduced as a continuous-phase protective colloid to stabilise the developing latex and to control particle size, coagulum formation, and final dispersion viscosity. The addition window is 2.0–5.0 wt% of total vinyl acetate monomer feed, with nonionic alcohol ethoxylate surfactant used at 0.5–1.2 wt% of monomer only as a co-surfactant. Exceeding 5.0 wt% POVAL 11-98 frequently produces emulsions with Brookfield viscosity above 25,000 mPa·s at 20 °C, increasing jacket cooling load during the exothermic polymerisation peak and making final viscosity difficult to reduce without excessive dilution. The polymer is dissolved in softened water at 90–95 °C, filtered through a 100–150 µm basket strainer, and cooled to 45–55 °C before being charged into a jacketed glass-lined reactor equipped with an anchor or pitched-blade agitator running at 60–100 rpm. Vinyl acetate monomer is metered continuously over 2.5–4.0 h while ammonium persulfate initiator solution at 0.10–0.30 wt% of monomer is fed separately. Reaction temperature is maintained at 65–75 °C, and pH is held near 4.0–5.5 with sodium bicarbonate buffer. A representative batch yields a white polyvinyl acetate homopolymer dispersion with 48–52% solids and a median particle size of 0.5–1.5 µm. End-use adhesives formulated from this dispersion are tested for bond strength under EN 204/205 class D2 or D3 depending on crosslinker addition, with dispersion viscosity determined by ISO 2555 and pH by ISO 976. Terminal products include polyvinyl acetate wood assembly adhesives, paper and board laminating adhesives, and base dispersions for further compounding. Operational boundaries include avoiding direct addition of POVAL 11-98 powder into the monomer phase and preventing reactor temperature excursions above 80 °C during the initiator spike, which can destabilise the protective colloid layer.
Surface treatment of recycled linerboard and white-top testliner with KURARAY POVAL 11-98 is specified when base-paper internal bond strength falls below 300 J/m² under TAPPI T 569 or when the sheet contains excessive recycled-fiber fines that raise air permeability and print mottle. In size-press formulations, POVAL 11-98 is added at 0.8–2.0 wt% of the working solution, blended with oxidised starch at a PVA-to-starch solids ratio between 1:4 and 1:6. The metering size press is operated at 45–60 °C with rod or blade metering, and dry pick-up is controlled at 0.5–1.2 g/m² per side. The comparatively low solution viscosity of this grade, typically below 300 mPa·s at 10% solids and 50 °C, reduces blade load and misting while allowing stable film split at line speeds of 300–600 m/min. POVAL 11-98 is pre-dispersed in cold demineralised water and jet-cooked at 95 °C for 20 min, then blended with the starch stream at 60 °C before the press holding tank. The terminal paper grades include food-safe folding cartons, corrugated medium and top liner, and printing-grade packaging board. In US food-contact applications, POVAL 11-98 is permitted as a component of paper and paperboard in contact with aqueous and fatty foods under 21 CFR 176.170, while EU conformance is managed under Regulation (EC) No 1935/2004 Article 3 with migration testing performed according to EN 1186 series where applicable. Mills operating with closed water loops should monitor size bath viscosity every 30 min because fines and calcium ions from recycled furnish can raise gel temperature and cause deposit formation on the metering rod.
Dry-pressed technical ceramics and piezoelectric ceramic green bodies require a temporary organic binder that decomposes before the vitrification ramp without leaving carbon residue. KURARAY POVAL 11-98 is incorporated at 0.5–2.0 wt% of ceramic powder in spray-dried granules, expressed as binder solids on dry ceramic mass. The binder solution is prepared at 2–5 wt% solids and dosed into alumina or barium titanate slurry before spray drying at inlet air temperature of 180–220 °C and outlet air temperature of 80–100 °C. Spray-dried granules with residual moisture of 0.2–0.8% are compacted at 50–100 MPa in hydraulic presses, producing green density of 55–65% of theoretical and sufficient green flexural strength for machining and handling. POVAL 11-98 burnout is conducted in air at 350–500 °C with a heating ramp of 1–2 °C per minute to avoid intragranular pressure from volatile decomposition products. Green density is measured by the Archimedes method under ISO 18754. Terminal products include alumina substrates, piezoelectric discs for transducers, and technical ceramic cores for investment casting. The principal operational limitation is hygroscopic uptake in humid plant air; granules stored above 60% relative humidity can re-absorb moisture, reduce flowability on the press feed shoe, and cause density scatter across the compact. In such environments, sealed storage or silica-gel drying of the binder powder at 25–35 °C is required before weighing.
KURARAY POVAL 11-98 is used in water-soluble film formulations as a higher-hydrolysis film-forming resin where high tensile strength and reduced cold-water solubility are required. The grade is blended with plasticiser and, in many grades, with a lower-hydrolysis PVOH at a mass ratio of 70–90% POVAL 11-98 to 10–30% lower-hydrolysis grade to shift dissolution temperature into a defined range. Cast film formulations are prepared at 15–20 wt% total solids, with glycerol or sorbitol plasticiser at 10–25 phr of total PVOH. The solution is filtered, deaerated under vacuum, and cast through a slot die onto a chrome-plated steel belt at 60–75 °C; dryer sections ramp from 90 °C to 130 °C, yielding film in the 35–70 µm thickness range. Conditioning at 20–25 °C and 30–50% relative humidity for 24–48 h before slitting is required to prevent blocking and dimensional drift. Terminal products include water-soluble sachets for detergent and agrochemical applications, embroidery backing film, and cleaning-product release films. Compliance in detergent unit-dose packaging is tied to Detergents Regulation (EC) No 648/2004, and where food-contact transfer is possible, to (EU) No 10/2011 with overall migration tested under EN 1186-3. The dissolution temperature must be re-validated after any change in plasticiser level above 5 phr because the high hydrolysis content of POVAL 11-98 produces a steeper viscosity rise during drying, which can generate film thickness variation across the web.
Adhesive compounding for spiral paper tube winding selects KURARAY POVAL 11-98 when substrates with high recycled fibre content demand rapid wet tack development and low cold flow after bond formation. The grade is formulated into an aqueous adhesive at 8–12 wt% solids, with plasticiser at 2–5 phr and, in formulations requiring higher shear viscosity, a borate donor below 0.05 wt% of the total batch. The adhesive is applied by engraved roll or doctor roll at 30–45 °C onto uncoated recycled paper; open time before winding is limited to 10–30 s, and nip pressure between paper plies during spiral winding is set at 0.2–0.6 MPa. Line speed is adjusted between 30–60 m/min depending on tube diameter and ply count. The resulting spiral tubes are cut into cores for flexible packaging films, tapes, labels, laminating materials, and industrial fabric winding. Flat crush resistance of the finished core is evaluated under ISO 11093-9. Where borate is used, the adhesive formulator must track boron release under REACH Annex XVII Entry 30, which restricts boric acid and borate compounds in mixtures supplied for general industrial use. The main process failure mode observed on tube winding lines is viscosity drift caused by re-circulation through the doctor roll chamber; a re-circulation time above 4 h at 45 °C can initiate skin formation at the tank walls, requiring 50–100 µm filtration to prevent coating streaks.
| Downstream segment | Compliance boundary | Test designation | POVAL 11-98 addition window |
|---|---|---|---|
| Warp sizing for air-jet looms | OEKO-TEX Standard 100 Class II; ZDHC MRSL 2.0 | ASTM D2256/D2256M-21 | 30–50 wt% of dry size solids |
| PVAc emulsion polymerisation | EN 204/205 D2/D3; ISO 2555 | ISO 2555 | 2.0–5.0 wt% of monomer |
| Recycled linerboard size press | FDA 21 CFR 176.170; EC 1935/2004 Article 3 | TAPPI T 569 | 0.8–2.0 wt% of size press solution |
| Technical ceramic green bodies | ISO 18754 green density | ISO 18754 | 0.5–2.0 wt% of ceramic powder |
| Water-soluble cast film | EC 648/2004; EN 1186-3 | EN 1186-3 | 70–90 wt% of PVOH blend |
| Spiral paper tube adhesives | REACH Annex XVII Entry 30 | ISO 11093-9 | 8–12 wt% adhesive solids |
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KURARAY POVAL 11-98 is a fully hydrolyzed polyvinyl alcohol grade, CAS 9002-89-5, produced by controlled alcoholysis of polyvinyl acetate. The numerical designation identifies two separate product attributes: the first segment corresponds to the nominal dynamic viscosity of a 4% aqueous solution at 20 °C, specified within 10.0–13.0 mPa·s, and the second segment corresponds to a degree of hydrolysis of 98.0–99.0 mol%. The residual acetyl content is therefore below approximately 2 mol%, which places the material in the fully hydrolyzed class rather than the partially hydrolyzed class. It is supplied as white to pale yellow granules, with specification limits based on the polyvinyl alcohol test methodology of JIS K6726. Exact molecular weight distribution is not disclosed on the standard certificate of analysis; the viscosity designation functions as the industrial surrogate for molecular weight.
| Property | Specification or Typical Value | Method |
|---|---|---|
| Degree of hydrolysis | 98.0–99.0 mol% | JIS K6726 |
| Viscosity, 4% aqueous solution at 20 °C | 10.0–13.0 mPa·s | JIS K6726 |
| Volatile matter | ≤ 5.0% | JIS K6726 |
| Ash as Na₂O | ≤ 0.5% | JIS K6726 |
| pH, 4% aqueous solution at 20 °C | 5.0–7.0 | JIS K6726 |
The specification values are nominal industrial limits and should be checked against the supplier certificate of analysis for each batch. Viscosity is controlled within the stated range, but dissolution behaviour can shift with granule particle size, residual acetate distribution, and storage history. Published data for this specific configuration is limited where end-use performance is concerned, because the polymer interacts strongly with co-binders, pigments, and process water hardness.
Fully hydrolyzed PVOH such as 11-98 differs from partially hydrolyzed grades in solubility temperature, surface activity, and dry-film crystallinity. The high degree of hydrolysis permits strong intermolecular hydrogen bonding after drying, which raises tensile strength and oxygen barrier character but reduces cold-water re-dispersibility. An 87–89 mol% grade ordinarily disperses or dissolves at ambient temperature, whereas a 98.0–99.0 mol% grade requires heating above 80 °C. Industrial dissolution is typically conducted at 85–95 °C for 30–60 min under low-shear agitation; below this window, incomplete hydration leaves microgel particles and visible fisheyes in coating films.
The glass transition temperature of the dry polymer is reported in the range of 75–85 °C for fully hydrolyzed PVOH, though plasticizers such as glycerol or polyethylene glycol depress this value and reduce film brittleness. The higher crystallinity of 11-98 reduces equilibrium moisture uptake relative to partially hydrolyzed grades, but it also means that dried films are not easily removed with ambient water. In adhesive systems, this property improves water resistance after film formation but imposes open-time and wetting constraints on nonporous substrates. When replacing a lower-hydrolysis grade, formulators should evaluate tack development, wetting speed, and film clarity, because the higher crystallinity of 11-98 can reduce immediate tack on filmic or coated paper surfaces.
Compared with higher-viscosity fully hydrolyzed PVOH grades, 11-98 gives lower solution viscosity and better filtration through fine screens. The lower viscosity reduces stringing in roll-coat and size-press applications, but the wet film may exhibit slightly lower green strength. The grade is therefore selected when clean transfer and penetration into porous substrates are more important than maximum film toughness. The degree of polymerization corresponding to 11-98 is not routinely specified; the viscosity designation is the primary control parameter.
Paper surface sizing and paperboard coating operations use the grade as a strength agent and oil-grease barrier component in the size press or water box. A solution concentration of 2–8% solids is common, often blended with oxidized starch or cationic starch. The low-viscosity fully hydrolyzed structure allows penetration into the sheet and leaves a continuous surface film. On porous substrates, a 5% solution applied at 40–60 °C contributes to measurable improvements in IGT pick resistance, although the absolute result is strongly influenced by base paper formation, starch type, and calender pressure. Published data for this specific configuration is limited because standard printability methods such as ISO 3783 are not product-specific.
Textile warp sizing is another use environment in which the hydrolyzed structure provides abrasion resistance, low size shedding, and clean removal with hot water at 80–95 °C. In aqueous adhesives for paper, board, and wood bonding, the polymer is compounded at 5–15% solids with fillers, plasticizers, and preservatives. The solution viscosity of 10.0–13.0 mPa·s at 4% allows low-speed propeller mixing without excessive shear heating. High-shear mixing should be limited because air entrainment and shear-induced foam persist in fully hydrolyzed PVOH solutions and can destabilize roll-coat transfer. The dry film is repulpable under alkaline conditions but is not readily removed with cold water, which limits its use in removable adhesive formulations.
The grade can act as a protective colloid in emulsion polymerization where higher water resistance and coalescence stability are required. Fully hydrolyzed grades show lower surface activity than partially hydrolyzed grades; therefore, when 11-98 replaces an 88 mol% grade in vinyl acetate or acrylic emulsion systems, particle size may broaden and initiator efficiency may shift. The lower residual acetate content reduces hydration at the latex particle surface and can increase latex viscosity under identical solids. This is not a defect, but it requires rebalancing of surfactant level and monomer feed rate. 11-98 is not recommended as the sole emulsifier for high-solids acrylic latex where fine particle size below 150 nm is required; partially hydrolyzed grades provide lower interfacial tension in such systems.
Polyvinyl alcohol is hygroscopic, and 11-98 granules equilibrate with ambient moisture. At storage relative humidity above 60%, the granules increase in moisture content; direct melt processing or extrusion without pre-drying creates steam at the die, bubbles in the film, and reduced melt strength. Pre-drying at 60–80 °C for 2–4 h in a desiccant dryer or a circulating-air oven is required before melt processing. The bed depth should not exceed 5 cm to ensure uniform moisture removal, and airflow should be sufficient to sweep released moisture away from the granule bed. After drying, the material should be protected from moisture regain, because rehydration can occur within 30–60 min at 50–60% relative humidity. Drying above 100 °C risks particle discolouration and sintering; the dryer should have independent temperature control and continuous airflow monitoring.
Material stored in outdoor silos without humidity control is not recommended for high-quality film or coating applications. If moisture uptake has occurred, the bulk density can shift slightly, but the primary processing risk is volatile steam generation rather than bulk flow failure. The granules should not be stored adjacent to acids, oxidizing agents, or aldehyde-functional crosslinkers, because acetal formation can occur and the resulting product may no longer dissolve as intended.
Fully hydrolyzed grades require hot water for dissolution, but the order of water and granule addition determines lump formation. The granules should be added to a vortex of cold or ambient water first and then heated; direct addition of granules to water already at 80–95 °C causes surface gelling and the formation of translucent fisheyes. Jet cookers with direct steam injection can be used only when steam is mixed under high turbulence and the solids concentration is below 10%. After dissolution, the solution should be held at 85–95 °C for at least 30 min and filtered through a 100–150 µm screen before use. The viscosity of a 4% solution at 20 °C should be confirmed against the certificate of analysis; incomplete dissolution will lower the measured value, while evaporative losses will raise it. Agitators should be low-shear; high-shear cowles blades above 1000 rpm can generate foam and reduce the effective concentration at the coating die.
In size-press operations, circulation temperature is generally maintained at 60–70 °C to prevent viscosity drift at the metering nip. Plate heat exchangers are preferred over direct steam injection when shear-sensitive rheology matters, because local overheating at the steam contact point can create insoluble gel specks. The solution should be filtered close to the point of application, not only at the mix tank discharge, because viscosity changes and slight gel formation during holding can occur.
Food-contact use is covered only where the final article meets the intended-use conditions in FDA 21 CFR 176.170 for paper and paperboard components and FDA 21 CFR 175.105 for adhesives. The grade itself is not a direct food additive and must not be used as a food ingredient. For EU supply, the substance is supplied under REACH polymer obligations according to EC 1907/2006; the supplier safety data sheet should be obtained before industrial use. No SVHC above 0.1% w/w is declared based on supplier documentation, but users must verify batch-specific heavy metal residues for electronics packaging or food-contact articles. RoHS does not directly apply to polymeric PVOH, though residual heavy metal limits may be relevant in certain electronic assembly specifications.
| Standard or Regulation | Scope | Relevance to 11-98 |
|---|---|---|
| FDA 21 CFR 176.170 | Components of paper and paperboard in contact with aqueous and fatty foods | Use as a strength or barrier component subject to conditions of use |
| FDA 21 CFR 175.105 | Adhesives for food packaging | Use in food-contact adhesives subject to good manufacturing practice |
| JIS K6726 | Test methods for polyvinyl alcohol | Specification verification for viscosity, hydrolysis, ash, and volatiles |
| REACH EC 1907/2006 | EU chemical regulation | Polymer registration and safety data sheet obligations |
Operational limitations include incompatibility with concentrated acids, strong oxidizers, and aldehyde-functional crosslinkers, which can form acetals or degrade the polymer. The dry granule is combustible as a dust; dust suppression and grounding measures should be used during bulk transfer. Aqueous solutions have limited shelf life and require preservatives if stored below 60 °C for more than 24 h, because microbiological growth can develop. The grade is not intended for medical implant, parenteral, or direct food-ingredient use.
