| HS Code | 558933 |
| Product Name | KURARAY POVAL 60-98 |
| Chemical Type | Polyvinyl alcohol (98% hydrolyzed) |
| Cas Number | 9002-89-5 |
| Molecular Formula | (C2H4O)n |
| Appearance | White granular powder |
| Degree Of Hydrolysis | 98.0 - 99.0 mol% |
| Viscosity 4 Percent Aqueous Solution At 20c | 60.0 - 70.0 mPa·s |
| Ph 4 Percent Solution | 5.0 - 7.0 |
| Volatile Content | max 5.0 wt% |
| Ash Content | max 0.7 wt% |
| Specific Gravity | 1.27 - 1.31 |
| Bulk Density | 0.4 - 0.6 g/cm3 |
| Melting Point Approx | 230 °C |
| Solubility | Soluble in hot water; insoluble in most organic solvents |
As an accredited KURARAY POVAL 60-98 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Kuraray Poval 60-98 polyvinyl alcohol is packaged in 25 kg multi-wall paper bags with a polyethylene liner for protection. |
| Container Loading (20′ FCL) | 20′ FCL loaded with palletized 25 kg bags, secured and dry, ensuring safe transport of Kuraray Poval 60-98. |
| Shipping | KURARAY POVAL 60-98 is a water-soluble polyvinyl alcohol resin powder, requiring moisture-proof packaging. Ship in sealed bags on pallets inside clean, dry containers. Protect from humidity, rain, and direct sunlight. It is non-hazardous under standard transport regulations; however, avoid dust generation and handle with care to prevent bag damage during transit. |
| Storage | Store KURARAY POVAL 60-98 in a cool, dry, well-ventilated area away from moisture, heat, open flames, and oxidizing agents. Keep containers tightly closed when not in use. Protect from dust accumulation and physical damage. Ensure proper labeling and handling to prevent spills or airborne particles. |
| Shelf Life | Shelf life of KURARAY POVAL 60-98 is typically 24 months from manufacture when stored in original, unopened containers under cool, dry conditions. |
In high-density warp sizing for air-jet weaving, KURARAY POVAL 60-98 is supplied as a fully hydrolyzed film former with a 4% aqueous solution viscosity of 58–66 mPa·s at 20°C. The degree of hydrolysis is 98.0–99.0 mol%. The grade has a pH of 5–7 as a 4% solution. Size mixes for polyester/cotton spun yarns are run at 9–14% dry solids. The size box is held at 82–88°C. A double-squeeze nip controls dry add-on to 10–14% on yarn weight. Yarn tensile retention after sizing is evaluated by ASTM D2256. Single-end abrasion resistance is measured on a Zweigle yarn abrasion tester. Shedding at the reed is reduced when 5–8% of a hydrolyzed starch or acrylic size is added on PVA dry weight. The dry film has a glass transition near 75–80°C and becomes brittle below 45% relative humidity. Cylinder dryer temperatures are controlled to 110–130°C. Residual yarn moisture after drying is held at 8–10%. Desizing uses 90–95°C water with 0.5–1.0 g/L nonionic wetting agent. Residual PVA above 0.5% on greige fabric interferes with caustic mercerization.
On fine paper machines with a pond-size or film-size press, POVAL 60-98 is pre-dissolved at 10–15% solids in a high-shear mixer. The solution is metered into oxidized starch at the size press run tank. Typical working solids are 6–10%. Between 20% and 30% of the starch dry solids is replaced by PVA. Surface strength is measured by ISO 3783. Internal sizing is held at 1–2 kg/t AKD or ASA depending on the base sheet. Size press pickup is controlled to 1.5–3.0 g/m² per side. Cobb values are measured by ISO 535. Run tank screens of 100 mesh (149 μm) prevent undispersed gel particles from reaching the press roll. Brookfield viscosity of the size press liquor is kept between 40–120 mPa·s at 60°C. The pH of oxidized starch is adjusted to 6.5–7.5 before PVA addition. Fully hydrolyzed PVA is stable at neutral pH but can gel under strongly alkaline conditions. For food-contact board, the converter must confirm compliance under FDA 21 CFR 176.170 or 176.180. Published data for the exact IGT improvement at every machine speed is limited and must be confirmed on the target furnish.
Spray-dried alumina and zirconia press bodies use POVAL 60-98 as a temporary organic binder. Slurry solids are typically 40–50% by mass. The binder addition is 1.0–2.5 wt% on dry ceramic solids. A dispersant is added before the PVA to prevent premature flocculation. Spray dryer inlet temperature is set at 180–220°C. Outlet temperature is maintained at 90–110°C. Spray nozzle type is selected for a median agglomerate size of 50–150 μm. Green compact strength is measured by biaxial flexure using ASTM C1499. When binder content falls below 1.2 wt%, edge chipping rises and green density declines. The high degree of hydrolysis of 98.0–99.0 mol% reduces hygroscopic swelling compared with partially hydrolyzed binders. Dynamic vapour sorption at 25°C and 60% relative humidity is used to compare equilibrium moisture uptake between grades. Pressing at 80–120 MPa produces uniform density gradients. Debinding is staged to 500°C at 1°C/min. Ash content of the product is specified at ≤0.5%. Spray dryer nozzle fouling occurs when the PVA solution is introduced at concentrations above 15% or when the feed temperature drops below 60°C.
Spiral tube winding lines running recycled linerboard at 80–150 m/min require an adhesive with high wet tack and stable viscosity under shear. POVAL 60-98 is cooked with starch and calcium carbonate clay to form a viscous aqueous adhesive. Wet viscosity is adjusted to 3000–5000 mPa·s at 25°C using a Brookfield RV spindle no. 7 at 20 rpm. The pH is kept at 6.0–7.5. Wet adhesive is applied by a slotted roller. Compression strength of the finished paperboard core is measured by ISO 11093-9. Borax use is limited to below 0.2% of wet adhesive because the 1,3-diol units of PVA form a gel network. The gel causes viscosity spikes in the return trough and starves the applicator roll. Adhesive skinning in the pan is reduced by maintaining relative humidity above 60% near the roller. Cleanup uses hot water at 70–80°C. The high degree of hydrolysis of 98.0–99.0 mol% gives water resistance to the dry bond after tube cutting.
In pigmented topcoats for folding boxboard, POVAL 60-98 is used as a co-binder at 0.5–2.0 parts per 100 parts of total pigment. The pigment blend is typically 60–80% calcium carbonate and 20–40% kaolin. A styrene-butadiene latex is the primary binder. PVA solution is added to the coating colour after pigment dispersion. Brookfield viscosity at 100 rpm is held between 600–1500 mPa·s. Static water retention is measured by pressure filtration at 0.5 bar. The dry topcoat is calendered. Surface strength is measured by ISO 3783. Wet pick resistance is measured by a Prufbau printability tester using a defined fountain solution. PVA replacement of more than 20% of latex dry solids raises Cobb water absorption above 35 g/m². PVA addition above 2.0 parts can increase shear viscosity and cause blade bleeding on high-speed metering coaters. The coating colour should be screened through 125 μm before delivery to the blade.
Remoistenable adhesives for envelopes use POVAL 60-98 as the primary film former. A typical solution contains 12–18% PVA, 2–4% glycerin or polyethylene glycol plasticizer, and 0.05–0.10% preservative. The adhesive is coated at 5–8 g/m² dry film weight on wove envelope stock. Drying is carried out in a forced-air tunnel at 70–85°C. The dry film remains water-soluble at 20–25°C after rewetting. Blocking is checked by stacking coated blanks under 0.5 MPa pressure at 40°C and 80% relative humidity for 24 h. The high degree of hydrolysis 98.0–99.0 mol% reduces cold-water tack and improves non-blocking compared with partially hydrolyzed grades. Rewetting time on a wet sponge applicator is controlled to 3–5 s before sealing. Viscosity drift in the coating pan occurs when the solution is held above 50°C for more than 8 h. The pan jacket is cooled to 30–35°C to reduce drift.
In machine-applied gypsum plasters, POVAL 60-98 functions as a water-retention additive at 0.1–0.5% by weight of dry solids. The product is dry-blended with hemihydrate and aggregates before the spray nozzle. Water addition is set by the plasterer to achieve a stiff but pumpable consistency. Water retention is measured by filter paper absorption according to EN 13279-1. The grade extends open time while final set measured by a Vicat needle is retarded by less than 5–10%. Mix viscosity under shear remains lower than cellulose ether formulations at the same water retention. Spray nozzle clogging is avoided by pre-dispersing PVA in a 5–8% stock solution before adding to the dry mix. At relative humidity above 70%, the dried plaster surface can become tacky if the PVA dosage exceeds 0.5%. The product must meet EN 13279-1 for gypsum plasters in building construction.
Open-mould glass-fibre laminating with epoxy or polyester resin can use a water-soluble release film based on POVAL 60-98. A 5–8% aqueous solution is applied by brush or spray to a mould surface. The film dries at 20–25°C to a thickness of 20–40 μm. The film is insoluble in styrene and protects the mould from resin adhesion. After demoulding the PVA layer is washed off with warm water at 35–45°C. The grade has a 4% solution viscosity of 58–66 mPa·s, which controls sagging on vertical mould surfaces. At relative humidity above 75%, the dried film absorbs water and softens. The application environment must be dehumidified. Published data for this specific configuration is limited for autoclave curing above 120°C. At those temperatures the release film must be tested for adhesion loss.
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KURARAY POVAL 60-98 is a polyvinyl alcohol resin with CAS 9002-89-5, supplied as a granular or fine powder. The grade designation encodes a nominal 4% aqueous solution viscosity of 60 mPa·s at 20°C and a nominal degree of hydrolysis of 98 mol%. Certificate-of-analysis limits commonly reported under JIS K6726 include degree of hydrolysis 98.0–99.0 mol%, 4% solution viscosity 60.0–68.0 mPa·s, volatile matter ≤5.0%, ash ≤0.5%, and pH 5.0–7.0 in a 4% aqueous solution. Residual acetate groups are therefore limited to approximately 1.0–2.0 mol%, which places the grade in the high-hydrolysis category and gives dried films low cold-water solubility. Compared with lower-viscosity POVAL grades such as 28-99, the 60-98 grade produces higher solution viscosity at equal solids and higher chain entanglement in aqueous formulations. Compared with partially hydrolysed grades such as 48-80, the higher degree of hydrolysis reduces water sensitivity after drying but narrows the dissolution window and requires higher processing temperatures.
The product may be used as a temporary binder, protective colloid, film former, or polar surface-size resin, but formulation design must account for the marked viscosity increase below 40°C in high-solids solutions and for incompatibility with certain borate and high-sulphate additives. The data below describe the grade in relation to adjacent POVAL types and typical industrial processing conditions.
In vinyl acetate emulsion polymerization, the polyvinyl alcohol protective colloid controls particle size distribution, latex stability, and adhesion after drying. POVAL 60-98 is employed at 1.0–3.0 wt% on monomer. At a given colloid concentration, the higher molecular weight of 60-98 relative to 28-99 raises continuous-phase viscosity and shifts particle size toward a larger mean diameter when measured by laser diffraction. In a 2 L reactor with an anchor stirrer, the higher solution viscosity reduces monomer droplet coalescence but increases agitation torque relative to POVAL 28-99. Against POVAL 48-80, which has a degree of hydrolysis of 79.0–82.0 mol% and retains cold-water dispersibility, POVAL 60-98 contains 98.0–99.0 mol% hydrolysis and imparts lower water sensitivity after film formation. The hydrophobic residual acetate content of 60-98 is below 2.0 mol%, so its surface activity in polymerization is lower than that of partially hydrolysed grades. Grafting frequency onto the polyvinyl alcohol backbone increases with molecular weight, which can improve particle steric stabilization but may also cause higher latex viscosity.
| Property | 60-98 | 28-99 | 48-80 |
|---|---|---|---|
| 4% solution viscosity at 20°C | 60.0–68.0 mPa·s | 26.0–30.0 mPa·s | 44.0–52.0 mPa·s |
| Degree of hydrolysis | 98.0–99.0 mol% | 99.0–100.0 mol% | 79.0–82.0 mol% |
| Volatile matter | ≤5.0% | ≤5.0% | ≤5.0% |
| Ash content | ≤0.5% | ≤0.5% | ≤0.5% |
| pH of 4% solution | 5.0–7.0 | 5.0–7.0 | 5.0–7.0 |
| Cold-water solubility of dried film | Low | Very low | Moderate to high |
POVAL 80-98, where available, gives a still higher viscosity than 60-98. The 60-98 grade is therefore selected when increased cohesive strength and solution viscosity are required without reaching the higher mixing torque and transfer difficulties of 80-98 at solids above 6 wt%. The choice between 60-98 and 28-99 in adhesive formulations often depends on target bond strength and drying rheology; 60-98 yields stronger films but requires more heat and shear during dissolution.
For solution preparation, a jacketed vessel with a low-shear anchor impeller is charged with demineralized water at 15–25°C. POVAL 60-98 is added gradually under agitation at 200–500 rpm to disperse the powder before heating. The suspension is heated to 90–95°C and held for 45–60 min. Complete dissolution is verified by cooling a sample to 20°C and confirming a viscosity within 60.0–68.0 mPa·s under JIS K6726. At solids above 8 wt%, the solution becomes strongly pseudoplastic and may require post-treatment with a rotor-stator homogeniser at 3,000 rpm for 10 min to break hydrogen-bond-associated clusters. The dissolution temperature must stay above 85°C; below this threshold, undissolved gel particles persist because the high degree of hydrolysis produces semicrystalline regions that swell slowly. The processing window is narrower than for POVAL 48-80, which dissolves more readily at lower temperature but gives films with greater water sensitivity.
Cast films of POVAL 60-98 at 10 wt% solids on chrome-plated steel substrates and dried at 105°C for 30 min develop a semicrystalline layer. Tensile testing per ASTM D882-18 on 50 µm films conditioned at 50% RH typically shows tensile strength in the range 40–80 MPa and elongation at break between 150% and 250%. These values depend on residual moisture, plasticizer type, and drying history. The unplasticized film remains hydrophilic and can absorb more than 30% water after 24 h immersion at 23°C when assessed by the method of ISO 62. This water uptake limits the use of uncrosslinked 60-98 films in high-moisture barrier applications. The dried film is not redispersible in cold water; rewetting requires water at 85–95°C or an alkaline hydrolysis-promoting medium. In high-speed film casting, the elevated molecular weight of 60-98 raises elongational viscosity and may require a heated slot die or doctor-blade system to maintain uniform wet-film thickness.
In paperboard lamination and paper sizing, 60-98 is formulated at 3–6% solids with starch or dextrin. A pilot air-knife coater operating at 1.5–2.0 bar air pressure can apply a dry pickup of 2–5 g/m². Substitution of 48-80 with 60-98 raises wet bond after 30 min water soak and reduces tack redevelopment at humid storage. However, if the solution pH is adjusted above 9.0, residual acetate groups may undergo further hydrolysis over 48 h at 50°C, shifting pH and reducing viscosity. Adhesive storage in this condition should be limited to 24 h or maintained below 40°C. For indirect food-contact adhesive applications, the finished adhesive should comply with the applicable limitations of FDA 21 CFR 175.105; the specific end-use status must be confirmed on the finished formulation.
Formulations containing sodium tetraborate, boric acid, or gypsum may show a sharp viscosity increase or gelation because the 1,2-diol segments of high-hydrolysis PVA form reversible borate complexes. The effect is more pronounced in 60-98 than in partially hydrolysed 48-80. In ceramic binder systems where barium sulphate or calcium sulphate is added at 10–20 wt%, compatibility screening at 2 wt% PVA solids is required before scale-up. The dry powder should be stored below 60% relative humidity; exposure above 60% RH can cause surface hydration and irregular silo flow. Pre-drying at 60–80°C for 2–4 h restores powder flow but does not reverse hard crust formation. Strong oxidizers and cationic polyelectrolytes at pH above 7.0 should be excluded from liquid formulations without compatibility testing.
Textile warp sizing with 60-98 at 6–12% solids in a single-end sizing machine provides high fibre adhesion and abrasion resistance at low size add-on. Size add-on is measured gravimetrically after drying at 105°C to constant mass. Desizing requires hot water above 80°C with a nonionic wetting agent; cold-water desizing is ineffective for this grade. In ceramic tile body preparation, 60-98 is added at 0.5–1.5 wt% of dry body solids as a temporary binder. The low ash content of ≤0.5% limits inorganic residue after kiln burnout. Burnout of the organic phase is typically complete in the range 300–500°C, but furnace airflow must be sufficient to prevent carbonaceous residue.
