| HS Code | 883704 |
| Product Name | KURARAY POVAL 35-80 |
| Cas Number | 9002-89-5 |
| Chemical Family | Polyvinyl alcohol |
| Degree Of Hydrolysis | 80 mol% |
| Viscosity | 35 mPa·s (4% aqueous solution at 20°C) |
| Ph | 5.0–7.0 (4% aqueous solution) |
| Volatile Content | ≤ 5.0 wt% |
| Ash Content | ≤ 0.5 wt% |
| Bulk Density | 0.50–0.70 g/cm³ |
| True Density | 1.27 g/cm³ |
| Melting Point | approximately 190°C |
| Water Solubility | Soluble in water |
As an accredited KURARAY POVAL 35-80 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | KURARAY POVAL 35-80 is supplied in 20 kg net multi-wall paper bags with an inner polyethylene liner for safe storage and handling. |
| Container Loading (20′ FCL) | 20′ FCL container loading of KURARAY POVAL 35-80: 25 kg bags on pallets, shrink-wrapped, securely stowed for safe transport. |
| Shipping | KURARAY POVAL 35-80 is a polyvinyl alcohol resin supplied as granules/powder. Ship in sealed multi-ply paper bags or drums, protected from moisture and contamination. Use dry containers and avoid dust accumulation. Under normal conditions it is non-hazardous and not regulated for transport. Store in a cool, dry, ventilated area. |
| Storage | Store KURARAY POVAL 35-80 in a cool, dry, well-ventilated area away from heat, open flames, and direct sunlight. Keep the container tightly sealed to prevent moisture absorption, as the material is hygroscopic. Store away from incompatible substances and oxidizers. Ensure proper labeling and handling to avoid dust accumulation. Use appropriate personal protective equipment when handling. |
| Shelf Life | KURARAY POVAL 35-80 has a shelf life of approximately 2 years when stored unopened in a cool, dry place. |
In suspension vinyl chloride polymerization, KURARAY POVAL 35-80 is deployed as a secondary suspending agent, not as a primary droplet stabilizer. The grade carries a degree of hydrolysis of 80.0 ± 1.0 mol% and a 4 wt% aqueous solution viscosity of 35.0–43.0 mPa·s at 20°C, placing it in the high-polymerization-degree class. The polymer is charged at 0.02–0.04 parts per 100 parts vinyl chloride monomer in recipes where a 70–74 mol% hydrolyzed primary dispersant supplies initial droplet subdivision. Total polyvinyl alcohol loading is held between 0.05 and 0.10 wt% of the monomer charge. The residual acetyl content at 20 mol% provides interfacial activity at the vinyl chloride–water boundary, while the high chain length restricts droplet coalescence after 30–40% conversion, the stage where resin particle identity becomes mechanically established. The reaction is run in a glass-lined or stainless-steel autoclave of 5–50 m³ working volume fitted with a Pfaudler retreat-blade impeller. Jacket temperature is set between 50°C and 70°C and vapor pressure between 6.9 and 10.3 bar. Impeller tip speed is maintained at 4.0–7.0 m/s; higher tip speeds generate excessive turbulent shear that smears primary-particle aggregates and reduces porosity. The primary-particle network formed in the presence of 35-80 produces a suspension PVC grain with higher porosity and lower apparent bulk density than dispersant packages composed entirely of 72 mol% hydrolysis grades. This porosity is functionally linked to plasticizer uptake and gelation behavior during downstream dry blending. Resin produced with the secondary dispersant at the upper addition limit of 0.04 phr may exhibit a narrower cold plasticizer absorption window, tracked by ISO 4608 or an equivalent in-house method. End products include rigid pipe grades classified under ASTM D1755 and ISO 1452-1, window and technical profiles under EN 12608, and calendered film intermediates requiring controlled plasticizer absorption. In plant conversion, over-addition of the secondary PVA above 0.06 phr typically shifts the particle size distribution toward 50–60 µm fines because the hydrated graft layer prevents primary-particle fusion. Under-addition below 0.02 phr may trigger droplet coalescence after conversion exceeds 35%, producing oversized grains and reactor fouling. Process engineers therefore treat the secondary dispersant ratio as a narrow operating window, not as a low-sensitivity formulation variable.
Remoistenable adhesive systems for paper envelopes, label stock, and tube winding use KURARAY POVAL 35-80 at 3–8 wt% dry solids in water. The 80 mol% hydrolysis level allows dissolution at 20–25°C, whereas fully hydrolyzed PVA requires heating above 85°C and does not re-wet reliably. The tack plateau after remoistening is controlled by residual acetyl content, plasticizer level, and molecular weight. Glycerol or polyethylene glycol 400 is added at 0.5–1.5 wt% on PVA solids. A defoamer may be required at 0.05–0.2 wt% on total formulation to release microbubbles during drum mixing. The final adhesive viscosity at 25°C is usually held between 2,000 and 8,000 mPa·s, measured by Brookfield LVT spindle 3 at 12 rpm. Roll-coat or gravure application at 40–80 m/min deposits 2–5 g/m² dry adhesive. Drying tunnels run at 85–120°C and residual moisture is kept at 5–8%. Excess drying below 4% moisture embrittles the adhesive layer; insufficient drying above 10% induces blocking on the reel. End products include remoistenable envelope flaps, paper bag seams, label sheet joints, and spiral-wound paper tubes. In remoistening, water penetrates within 1–3 s and the adhesive develops shear resistance suitable for automatic filling lines. Because the grade is high in molecular weight, solution ageing must be monitored with a falling-ball or rotational viscometer. Batch-to-batch drift in residual acetate sequence distribution can alter redissolution speed even when bulk hydrolysis is within specification.
| Jurisdiction | Designation | Application boundary |
|---|---|---|
| United States | 21 CFR 175.105 | Adhesives for indirect food contact |
| United States | 21 CFR 176.170 | Paper and paperboard in aqueous and fatty food contact |
| United States | 21 CFR 176.180 | Paper and paperboard in dry food contact |
| European Union | REACH Regulation (EC) No 1907/2006 | Registered polymer; verify residual vinyl acetate monomer against applicable limits |
In slasher sizing of high-density cotton, polyester, and blended warps, KURARAY POVAL 35-80 is used as the primary film-forming size at 6–10 wt% total solids in the size box. The high degree of polymerization produces a film with sufficient tensile strength and abrasion resistance for high-speed weaving. A size box temperature of 75–85°C lowers solution viscosity during application, while the partially hydrolyzed structure remains soluble in the fiber moisture during desizing. Hydrogen peroxide or sodium hypochlorite oxidative desizing may not be required because PVA can be recovered by hot-water washing at 85–95°C, though wastewater unit load is influenced by recovery efficiency. Wax is added at 0.2–0.5 wt% on total size solids to reduce yarn-to-yarn friction. A quaternary ammonium antistatic agent is incorporated at 0.1–0.3 wt% to limit electrostatic fly on high-speed looms. Nip pressure in the size box is maintained between 2 and 4 bar to control size add-on. Slasher drying cans are staged from 110°C to 140°C; excessive first-can temperature causes skin formation and poor size penetration. Yarn moisture after drying is kept at 5–7%. Sized warp yarn tensile properties are checked by ASTM D2256. End products include woven shirting, bed linen, and technical fabric constructions where dense weave geometry would otherwise increase warp yarn abrasion failure during shedding and beat-up. Desizing effluent should be governed by the facility wastewater permit, and residual PVA in fabric before bleaching should be below detectable starch-iodine limit.
Technical ceramic granulation lines use KURARAY POVAL 35-80 as a temporary green binder for alumina, zirconia, and silicon carbide powder systems. The grade is added at 0.5–2.0 wt% of dry ceramic powder mass, with polyethylene glycol 400 added at 10–20 wt% on PVA solids as plasticizer. Aqueous slurry solids are maintained at 55–70 wt% before spray drying. Spray dryer inlet temperature is set at 180–230°C and outlet temperature at 80–110°C; the resulting press granules have a D50 between 60 and 150 µm. Uniaxial pressing at 80–150 MPa produces green bodies with 55–60% theoretical density. The PVA network contributes enough green strength to permit green machining without fracture. Binder removal is carried out at 450–550°C in air at 0.5–1.0°C/min; heating rates above 2°C/min cause internal pressure from decomposition gases and can delaminate thick cross-sections. Published data for the specific decomposition profile of this high-DP partially hydrolyzed grade in silicon carbide matrices is limited, so thermal profiling is recommended by thermogravimetric analysis before production. End products include alumina electronic substrates, zirconia oxygen sensor housings, and silicon carbide kiln furniture. Green density and binder distribution can be audited by Archimedes density measurement and burnout residue analysis.
After the ethylene pressure stabilizes and the initial vinyl acetate charge is emulsified, KURARAY POVAL 35-80 is introduced as a protective colloid at 2–5 wt% on total monomer. The high degree of polymerization raises colloidal stability through adsorbed-layer thickness, while the 80 mol% hydrolysis level controls graft reaction rate and viscosity build. The polymerization is operated as a semi-batch process with persulfate and sodium metabisulfite redox initiation at 60–70°C. pH is held between 4.0 and 5.5 to avoid acetate hydrolysis and to maintain initiator efficiency. Monomer delay is typically 3–4 h, which prevents localized vinyl acetate concentration spikes and reduces coagulum generation. When the polymerization charge contains 4 wt% or more of 35-80 on total monomer, final emulsion viscosity can exceed 10,000 mPa·s, especially if ethylene pressure is released too rapidly during letdown. Insufficient agitation in the heel stage creates a viscosity gradient that entrains unreacted monomer and produces coarse particles. End products include wood adhesives meeting EN 204 D3 or D4 classification, nonwoven binders, and textile flocking adhesives. The protective colloid remains in the dried film and contributes water sensitivity, so exterior wood bonding requires crosslinking or blending with dispersions of lower hydrolysis grade. Residual vinyl acetate monomer in the emulsion should be analyzed by gas chromatography and kept below regional permissible exposure thresholds. For indirect food-contact adhesive uses, the compounded formulation may be evaluated under FDA 21 CFR 175.105.
On dense clay-coated board and molded fiber, size-press or roll-coat application of KURARAY POVAL 35-80 creates a non-fluorinated grease barrier. The coating solution contains 4–8 wt% PVA, 5–10 wt% plasticizer on PVA solids, and 0.5–2.0 wt% glyoxal or ammonium zirconium carbonate crosslinker on PVA solids. The crosslinker reduces moisture sensitivity after drying. A defoamer is added at 0.05–0.2 wt% on total formulation. The coat weight after drying is maintained between 1.5 and 3.0 g/m². Drying is carried out at 100–130°C; residence time depends on substrate caliper and airflow. After 24 h conditioning at 23°C and 50% RH, coated samples are evaluated using TAPPI T559. A barrier coating weight of 2.5 g/m² can achieve Kit 8 on dense clay-coated board, but published data for this specific grade and substrate combination is limited. Plant trials should use incremental coat weight screening rather than a fixed specification. End products include paper plates, burger boxes, food service trays, and molded fiber containers. Compliance is assessed under FDA 21 CFR 176.170 for aqueous and fatty food contact and 21 CFR 176.180 for dry food contact.
| Component | Function | Typical range |
|---|---|---|
| KURARAY POVAL 35-80 | Film former and oil barrier | 4.0–8.0 wt% |
| Glycerol or PEG 400 | Plasticizer | 5–10 wt% on PVA solids |
| Glyoxal or ammonium zirconium carbonate | Crosslinker | 0.5–2.0 wt% on PVA solids |
| Defoamer | Foam control | 0.05–0.2 wt% on total formulation |
| Water | Solvent | Balance |
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KURARAY POVAL 35-80 is a partially saponified poly(vinyl alcohol) resin whose grade designation links two controlled parameters: the first number identifies the nominal 4% aqueous solution viscosity class, and the suffix denotes a nominal degree of hydrolysis of 80 mol%. The manufacturer’s specification for the 4% solution at 20 °C is 27.0–33.0 mPa·s, determined by the viscometric method of JIS K6726. The degree of hydrolysis is controlled between 78.5 mol% and 81.5 mol%, leaving a measurable residual acetyl content from the vinyl acetate monomer. Volatile matter is specified at not more than 5.0 wt%, and ignition residue is specified at not more than 0.5 wt%. The 4% aqueous solution has a pH range of 5.0–7.0. The product is supplied as a solid granular material for waterborne applications; it is not a melt-processable thermoplastic unless plasticized or blended with polyols.
On production-scale loss-in-weight feeders with agitated hoppers, pre-drying is generally not required for 35-80 when storage relative humidity remains below 60%. Above that threshold, moisture uptake can create lumps that reduce feed accuracy and increase dissolution time. Batch-to-batch viscosity variation within the 27.0–33.0 mPa·s band should be normalized by adjusting solid content when the downstream process uses a fixed Brookfield viscosity target.
| Grade | 4% aqueous viscosity at 20 °C (mPa·s) | Degree of hydrolysis (mol%) | Volatile matter max (wt%) | Ignition residue max (wt%) |
|---|---|---|---|---|
| POVAL 5-88 | 5.0–6.0 | 86.5–89.0 | 5.0 | 0.5 |
| POVAL 22-88 | 20.5–24.5 | 86.5–89.0 | 5.0 | 0.5 |
| POVAL 28-98 | 26.0–30.0 | 98.0–99.0 | 5.0 | 0.5 |
| POVAL 35-80 | 27.0–33.0 | 78.5–81.5 | 5.0 | 0.5 |
The specification difference between 35-80 and 22-88 is twofold. At equal solids, 35-80 provides a higher continuous-phase viscosity because its 4% viscosity band is 27.0–33.0 mPa·s versus 20.5–24.5 mPa·s. It also has a lower degree of hydrolysis: 78.5–81.5 mol% versus 86.5–89.0 mol%. That difference alters solubility, surface activity, and dry-film water uptake. The residual hydrophobicity from acetyl groups in 35-80 lowers interchain hydrogen bonding and reduces the energy required for cold-water dispersion. In contrast, 28-98, with 98.0–99.0 mol% hydrolysis and a similar viscosity band of 26.0–30.0 mPa·s, offers better water resistance after film drying but requires a higher dissolution temperature. Consequently, 35-80 is selected when wet tack, open time, or emulsifying behaviour is more important than final water resistance.
Charge the powder into the vortex of a low-shear anchor-stirred vessel at 20–25 °C, then warm the batch to 85–90 °C and hold for 30–45 min at 60–80 rpm. High-shear introduction is avoided during the swelling phase because it can incorporate air and produce stable foam, particularly with this partially hydrolyzed grade. The solution is then cooled under slow agitation to 30–40 °C before addition to adhesive or emulsion reactors. Filtration through a 100 µm bag filter is standard in coating lines to remove gel skins that form when powder is wetted too rapidly. Published data for the exact swelling half-life at 20 °C in deionized water is limited; line operators typically judge completion by visual clarity and a stable Brookfield viscosity after cooling.
Vinyl acetate and vinyl acetate-ethylene copolymerizations use 35-80 as a predissolved 6–8 wt% stock solution charged as the continuous-phase protective colloid. The viscosity contribution of 35-80 is higher than that of 5-88 at the same mass fraction; direct substitution without adjustment will increase final emulsion viscosity and can reduce impeller pumping rate in a jacketed reactor. The product is suitable for wood-adhesive base emulsions and decorative coating binders where extended open time and high wet tack are processing advantages. Final emulsion viscosity is commonly measured with a Brookfield RVT viscometer at 20 °C, 20 rpm, spindle 4 or 5 after 24 h aging. If the target is 10 000–20 000 mPa·s, a formulation using 35-80 may require a lower colloid mass fraction than a formulation using 22-88 because the continuous-phase viscosity is governed by the 4% solution viscosity band.
Films cast from a 4% aqueous solution of 35-80 and dried at 40 °C for 48 h are optically clear and flexible. The partially acetylated chain has lower crystallinity than fully saponified grades, which reduces tensile modulus and increases elongation; however, it also increases sensitivity to water. For tensile testing, laboratories use ISO 527-3 on 50–100 µm cast films; for water resistance, a 24 h immersion at 23 °C in deionized water is used as a comparative test, not as a specification limit. When films based on 35-80 are compared with 28-98, water uptake is higher and wet tensile retention is lower. Additions of glyoxal or melamine resin are therefore used if the final bond must pass EN 204 / EN 205 durability classes for wood joints. Direct blending with borate salts produces strong viscosity increases and can be used only where controlled gel formation is desired; the borate crosslink is reversible and sensitive to pH and temperature.
Blade-coater lines for coated paperboard can use a solution of 35-80 at 8–12 wt% solids as a co-binder in starch-based coating colours to raise high-shear viscosity and improve pick strength. The lower hydrolysis level gives easier cleanup and fewer crystalline gel particles after line stops compared with fully hydrolyzed grades. Coating colour rheology is screened on a rotational viscometer at 1000 s⁻¹ and 20 000 s⁻¹ using cone-plate geometry; however, product-specific data on supercalendered paper gloss for this exact grade is limited. The grade is used more commonly where its high molecular weight contribution is valued, while optical performance is controlled primarily by pigment dispersion and calendering conditions.
KURARAY POVAL 35-80 is used in waterborne adhesives and coatings that may require indirect food-contact status. In the United States, poly(vinyl alcohol) may be used as a component of adhesives under 21 CFR 175.105 when the final adhesive formulation meets the conditions of that section; the resin alone does not carry a direct food-contact approval. The supplier’s REACH registration covers the substance as a registered polymer or intermediate; users must confirm current registration status and uses in the extended safety data sheet. The product is not classified as a dangerous substance under GHS. Due to dusting, local exhaust ventilation and respiratory protection meeting EN 149 particle-filtering half-mask requirements are standard in powder charging areas. During hot-water dissolution, open vessels should be maintained at atmospheric pressure, and the maximum recommended storage temperature for prepared solutions is 30 °C to avoid microbial growth. Preservative selection should avoid strong oxidizing agents and transition-metal catalysts that accelerate oxidative chain scission.
Ceramic green-tape processing uses a solution of 35-80 at 6–10 wt% solids as a temporary binder for alumina or zirconia slips. The high molecular weight of the grade improves green strength after tape casting. Green strength is evaluated by three-point bending following ISO 14704 or equivalent method; published data for 35-80 in this specific tape formulation is limited. The binder burnout profile must be adjusted because the partially hydrolyzed polymer begins thermal degradation near 250–300 °C; complete carbon removal in air requires residence at 450–500 °C for 2 h in a ventilated kiln. Residual ash must be matched to the 0.5 wt% maximum specification to avoid ceramic contamination.
The decisive selection parameter among POVAL grades is not viscosity alone but the ratio of viscosity to degree of hydrolysis. 35-80 sits in a deliberately narrow hydrolysis band with high solution viscosity. This combination supports high wet bond formation and high solution body at low addition levels, while sacrificing some dry-film water resistance compared with 28-98. It should not be used as a drop-in replacement for 5-88 in low-viscosity spray applications because its 4% solution viscosity is roughly fivefold to sixfold higher. Conversely, replacing 28-98 with 35-80 in barrier coatings will increase water sensitivity unless an external crosslinker is added. These comparisons are derived from the specification bands in the table and from the solution preparation methods of JIS K6726.
