| HS Code | 930023 |
| Chemicalname | Polyvinyl Alcohol (PVA) |
| Casnumber | 9002-89-5 |
| Molecularformula | (C2H4O)n |
| Appearance | White to cream granular powder |
| Viscosity | 18 mPa·s (4% aqueous solution at 20°C) |
| Degreeofhydrolysis | 98.0-98.8 mol% |
| Ph | 5.0-7.0 (4% aqueous solution) |
| Ashcontent | ≤1.0 wt% |
| Volatilecontent | ≤5.0 wt% |
| Density | 1.19-1.31 g/cm³ |
| Meltingpoint | ~230°C (fully hydrolyzed grade) |
| Glasstransitiontemperature | ~85°C |
| Solubility | Soluble in hot water; practically insoluble in cold water and most organic solvents |
| Tensilestrength | ~70 MPa (film) |
| Elongationatbreak | ~150% (film) |
| Refractiveindex | 1.49-1.53 |
As an accredited SELVOL Polyvinyl Alcohol 818 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 818 is supplied as free-flowing granules in 25 kg multi-wall paper bags, available with palletized packaging options. |
| Container Loading (20′ FCL) | SELVOL Polyvinyl Alcohol 818 is loaded into a 20-foot FCL, properly secured, sealed, and documented for safe transport. |
| Shipping | SELVOL Polyvinyl Alcohol 818 is not classified as dangerous goods for transport under IATA, IMDG, or ADR. Ship in sturdy, dry packaging protected from moisture and physical damage. No hazardous labeling required. During handling, minimize dust generation and follow standard industrial hygiene practices. Keep containers sealed when not in use. |
| Storage | Store SELVOL Polyvinyl Alcohol 818 in a cool, dry, well-ventilated area away from heat, sparks, and open flames. Keep containers tightly closed to prevent moisture absorption, as the product is hygroscopic. Avoid contact with strong oxidizers. Protect from physical damage and store off the floor on pallets, maintaining a clean, dry environment. |
| Shelf Life | Shelf life is typically 2 years from manufacture when stored in a cool, dry area in original unopened packaging. |
During high-speed horizontal form-fill-seal conversion of water-soluble detergent pods, Selvol PVOH 818 is blended into cast monolayer film to reduce solution rheology and to stabilise seal initiation below the point at which higher-molecular-weight PVOH grades form gel skins on the slot-die lip. Because the grade exhibits a 4%-solids aqueous viscosity of 5.0–7.0 mPa·s at 20°C and a hydrolysis range of 87–89 mol%, it is incorporated at 10–35 phr on total PVOH resin in a formulation containing 70–85 wt% PVOH, 10–20 phr glycerol or sorbitol-type plasticiser, and 0.5–2.0 phr synthetic silica anti-block. Dissolution is performed in deionised water at 18–25 wt% solids using a vacuum dissolver equipped with a rotor-stator or anchor impeller at 60–120 rpm; the solution is then deaerated under -0.08 MPa for no less than 20 min and cast through a slot die onto a chromium-plated steel belt with drying-zone air temperatures between 80°C and 130°C. Film is conditioned at 20–25°C and 40–50% RH before sealing on rotary or flat-bed unit-dose lines with bar temperatures of 140–190°C and dwell times of 200–600 ms. Peel symmetry failures are observed when ambient relative humidity falls below 35%, causing brittle crown fracture at the seal shoulder, or when pre-drying is omitted above 60% RH, leading to dissolved oxygen entrapment and microvoids. Regulatory references for this application include EC No 648/2004 Annex VII for detergent product safety, OECD 301B for ready biodegradability of the film former, ISO 527-3:2018 and ASTM D882-18 for tensile properties of free film, ASTM D1922-15 for Elmendorf tear, and EN 13432:2000 where industrial compostability of packaging is specified. Terminal converted products are laundry monodose packs, automatic dishwasher capsules, and water-soluble sachets for non-hazardous powder additives.
Within semi-batch emulsion polymerisation reactors producing vinyl acetate-ethylene copolymer dispersions, Selvol PVOH 818 is charged as a secondary protective colloid to narrow the latex particle size distribution and to avoid the high reactor torque that results from fully hydrolysed high-viscosity grades during the early nucleation phase. The grade is dissolved in deionised water to 5–10 wt% solids at 20–30°C and metered into the reactor at 0.1–2.0 wt% based on vinyl acetate monomer mass, either as a continuous delay feed over 90–240 min or as a split pre-charge of 30–50% of the total colloid addition. Polymerisation is operated at 40–60°C in a jacket-controlled glass-lined or stainless steel vessel with a three-blade propeller or anchor impeller at 60–120 rpm; redox initiation with hydrogen peroxide and sodium metabisulfite is employed to limit pre-nucleation viscosity. Residual acetate groups in the 87–89 mol% hydrolysed grade provide grafting onto the vinyl acetate phase, while the 5.0–7.0 mPa·s solution viscosity maintains a Brookfield-measured reactor latex viscosity below 5,000 mPa·s for high-solids dispersions above 60% solids. Compliance references include REACH (EC) No 1907/2006 for monomer and polymer registration, ISO 3251:2019 for non-volatile content, ISO 2555:2018 for Brookfield viscosity, and ISO 976:2013 for pH. Published migration data for this exact PVOH grade in VAE food-contact dispersions is limited; final food-contact suitability is established by extraction testing on the specific laminate under its intended end-use article standard rather than by grade substitution alone. Terminal product categories are VAE-based wood bonding adhesives, packaging laminating adhesives, nonwoven binder dispersions, and low-odour interior architectural caulks.
Alumina, silicon nitride, and cordierite spray-dried pressing granules are prepared with Selvol PVOH 818 as a low-ash green binder at 0.5–3.0 wt% of dry ceramic solids to control green-strength handling damage and to shift burnout residue below the level that would reduce sintered density. The binder is dissolved as a 3–6 wt% aqueous solution in warm deionised water at 40–60°C, then added to a ceramic slip containing 65–75 wt% solids during dispersed mixing; slurry outlet viscosity is maintained at 100–500 mPa·s as measured by a rotary viscometer to allow atomisation. Spray-drying is conducted on a co-current rotary or nozzle atomiser with inlet air temperature 180–230°C, outlet temperature 85–110°C, and residual moisture 0.5–2.0%. Pressing is performed on uniaxial hydraulic presses at 40–100 MPa, after which green body flexural strength is measured on rectangular bars under ASTM C1161-18; debinding is executed in an air or nitrogen-purged kiln with a ramp rate of 0.5–2.0°C/min between 200°C and 600°C to allow carbon oxidation without blistering. Sintered flexural strength is tested under ISO 14704:2016, and water absorption is assessed under ISO 10545-3:2018 where tiled formats are applicable. Terminal products are technical oxide substrates, wear-resistant inserts, porous ceramic filtration membranes, and kiln furniture where binder residual ash must not exceed 0.1 wt%. The explicit processing boundary is that above 3.0 wt% binder addition the debinding exotherm can screen excessively and create internal cracking in fine-grain compacts; below 0.5 wt% edge chipping increases markedly in automatic green-body handling.
Film press coaters producing aqueous inkjet receptive precoats and high-speed pigment-binding size-press formulations use Selvol PVOH 818 as a low-viscosity hydroxy-functional film former at 10–25 wt% of total size-press solids in a bath containing 6–10% dissolved solids, where the remaining mass is composed of surface-modified starch or polyacrylamide rheology modifiers. The addition ratio on dry base paper ranges from 0.2–1.0 wt% for inkjet colour-density control and from 0.5–1.5 wt% for water-resistant barrier precoat applications. The liquor is prepared in a twin-tank starch cooker at 85–95°C with a jet-cooker hold time of 20–40 min; Selvol 818 is first dissolved separately at 20–30°C in an eductor-equipped cold-water disperser to avoid lumping, then combined with cooked starch at the machine supply tank where viscosity is held between 80–200 mPa·s. Metering is performed by a rod-type film press or blade coater at web speeds of 800–1,500 m/min; after-treatment drying uses airborne dryers with air temperatures from 110–160°C, and sheet moisture is conditioned to 5–7% absolute before reeling to minimise curl. Laboratory control includes ISO 535:2014 for Cobb water absorption, ISO 2470-1:2016 for brightness, and ISO 8791-4:2007 for Parker Print Surf roughness. Regulatory compliance for food-contact board uses 21 CFR 176.170 components of paper and paperboard in contact with aqueous and fatty foods, but only when the total formulation is cleared under the specific conditions of use. Terminal product categories are pigmented inkjet photo base, water-based flexographic preprint liner, release-coated casting paper, and non-curling laminated folding carton stock. Process operators impose an upper addition limit of 1.5 wt% on dry paper because higher levels reduce size-press runnability through misting and trigger reel-blocking at ambient warehouse humidity above 70% RH.
A size bath containing Selvol PVOH 818 at 30–60 wt% of the polyvinyl alcohol component, with the remainder as acid-modified starch or acrylic size, is added to cotton and polyester-cotton warp yarns at a total size-box solids concentration of 8–14 wt% and a bath temperature of 85–95°C. The grade’s partial hydrolysis of 87–89 mol% and low solution viscosity allow the size film to redissolve during washing at 50–70°C, which reduces the need for aggressive desizing enzymes that can damage cellulosic yarns. Application is performed on single-end sizing machines with a multi-cylinder drying section; the first squeeze roll nip is controlled at 30–80 kN/m linear pressure and the final lease rod split angle is set between 10° and 25° to prevent size-chamfer cracking. Drying cylinder surface temperature is staged from 100°C to 140°C, with warp moisture after drying limited to 2–4% to prevent blocking on the loom beam. Sized yarn tensile strength and elongation are tested under ISO 13934-1:2013; size add-on is determined gravimetrically or by desizing loss under AATCC 97-2019 aqueous extraction, and abrasion resistance of sized warp yarns is quantified by a Zweigle or Reutlingen yarn abrasion instrument. Chemical compliance is governed by Oeko-Tex Standard 100 Annex 4 residual limits where final textiles are labelled for skin contact, and by REACH (EC) No 1907/2006 Article 33 candidate-list screening for any impurity present above 0.1 wt%. Terminal products are sized cotton warps for shirting, polyester-cotton warps for bed linen, and compact spun yarn warps used in high-density downproof weaving. The operational boundary is that if the size bath pH drifts below 4.5 through acidic starch degradation, Selvol 818 films become tacky on the drying cans and end breaks increase at the split rods.
Vinyl chloride monomer droplets are stabilised in suspension polymerisation reactors with Selvol PVOH 818 as a low-viscosity secondary dispersant at 0.04–0.12 wt% on vinyl chloride monomer mass, used alongside a primary high-hydrolysis PVOH grade at 0.03–0.08 wt% to control droplet coalescence during the critical 10–30% conversion stage. The dispersant is dissolved in deionised water at 20–30°C to 0.2–0.5 wt% aqueous concentration before charging to a 50–120 m³ jacketed polymerisation vessel at a water-to-VCM mass ratio of 1.0:1–1.4:1. Peroxide initiators such as di-2-ethylhexyl peroxydicarbonate are added at 0.02–0.10 wt% and polymerisation is run at 50–65°C with agitator tip speed between 2.5 m/s and 4.5 m/s, corresponding to a droplet size between 30 µm and 150 µm at the onset of suspension formation. Reactor pressure is controlled at 0.7–1.2 MPa until conversion reaches 75–85%; residual monomer is stripped under vacuum and recovered. Resin quality is classified under ASTM D1755-15, K-value under ISO 1628-2:2020, thermal stability under ISO 182-1:2015, and dry flow under ASTM D1895-17. Regulatory compliance includes REACH (EC) No 1907/2006 Annex XVII for vinyl chloride monomer residual below 1 ppm in the final resin, and FDA 21 CFR 177.1210 where the resin is used in sealing gaskets for food contact, if the finished article meets extraction limits. Terminal products are suspension PVC grades for pressure pipe, window profile, cable sheathing, clear film for packaging, and medical tubing compounds. The process limitation is that overdosing Selvol 818 above 0.15 wt% on VCM increases reactor foaming and produces PVC grains with excessive skin thickness, leading to fish-eye defects in plasticised calendered film.
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SELVOL Polyvinyl Alcohol 818 is a partially hydrolysed, medium-viscosity grade of polyvinyl alcohol manufactured by Sekisui Specialty Chemicals. The resin is supplied as a white granular solid and is identified in polymer inventories by CAS number 9002-89-5. Within the SELVOL 8xx partially hydrolysed series, the grade designation 818 corresponds to a nominal 4 % aqueous solution viscosity class of approximately 18–22 mPa·s at 20 °C when measured by Brookfield viscometry. Degree of hydrolysis is conventionally controlled within 87.0–89.0 mol%; this residual acetate content lowers the solubility temperature and modifies the hydrophilic/hydrophobic balance relative to fully hydrolysed polyvinyl alcohol. Because the exact release window for viscosity, pH, volatiles, ash, and methanol content can vary by manufacturing site and revision, lot acceptance should be performed against the current technical data sheet and the certificate of analysis rather than a single fixed interval.
For incoming resin quality control, the primary specification axes are 4 % solution viscosity, degree of hydrolysis, pH, and residue. Viscosity is commonly determined in accordance with ISO 12058-1 or ASTM D2196 using a 4 % aqueous solution at 20 °C. Degree of hydrolysis is measured by saponification titration, often following JIS K6726 or an internal method aligned with the same titre protocol. The pH of a 4 % solution is typically controlled within 4.5–7.0, and the product is generally specified to a maximum volatiles content of 5.0 wt% and a maximum ash content of 0.5 wt%. These values are not independent: a shift in hydrolysis above the upper bound raises the hot-water dissolution requirement, while a shift below the lower bound reduces film tensile strength and increases equilibrium water uptake.
The dissolution behaviour of SELVOL 818 differs from fully hydrolysed grades in practical processing terms. A cold-water charge of 10–25 °C is usually required for initial dispersion, with the powder introduced slowly into the shoulder of a vortex. The batch is then heated to 40–60 °C and held under high-shear dispersion to complete hydration. Fully hydrolysed polyvinyl alcohol, by comparison, normally requires 85–95 °C for complete dissolution. The lower dissolution temperature of SELVOL 818 makes it compatible with atmospheric mixing vessels that cannot sustain pressurised heating, but it also means that wet powder should not be introduced into a warm tank without pre-slurrying; the surface of the granules hydrates rapidly and can form gel skins that shield undissolved material. Equipment used on production lines typically includes rotor-stator batch mixers or eductor systems operating at tip speeds of 8–15 m/s. Solutions at 10–15 wt% solids are usually prepared in cold water and then heated, while higher-solids concentrates may require staged powder addition and a vacuum deaeration step to limit foam and microvoids.
In adhesive and emulsion polymerisation applications, SELVOL 818 functions primarily as a protective colloid, rheology modifier, and film former. The partially hydrolysed structure, with residual acetate groups of approximately 11–13 mol%, reduces aqueous solution surface tension relative to fully hydrolysed grades and improves wetting on hydrophobic substrates such as polyolefin-treated films and sized paper. In vinyl acetate emulsion polymerisation, the grade can be charged into the aqueous phase before initiation; its molecular weight and hydrolysis level influence graftability, particle size distribution, and final emulsion viscosity. A typical addition level may be 1.0–4.0 wt% of the dispersed phase, but the exact amount must be derived from rheological measurement because excessive PVOH can generate shear-thinning but highly viscous emulsions that exceed pumping limits. Brookfield RVT measurement at 20 rpm and 25 °C is commonly employed for batch release.
The principal difference between SELVOL 818 and adjacent grades in the 8xx partially hydrolysed series is molecular weight, observed as 4 % solution viscosity. SELVOL 818 is positioned as a medium-viscosity grade, placing it between lower-viscosity grades used for high-solids, lower-tack formulations and higher-viscosity grades selected for high tensile strength and water resistance. Compared with a higher-viscosity grade such as SELVOL 840, SELVOL 818 yields lower solution viscosity at equal solids, which permits easier spray application and faster pump transfer. The trade-off is reduced cohesive strength and increased sensitivity to moisture in cast films. Conversely, a grade with lower solution viscosity than SELVOL 818 typically allows higher solids loading in gravure or roll coating, but the dried film will exhibit lower tensile strength and lower resistance to blocking under humid storage. These comparisons are relevant only when hydrolysis is held constant; changing hydrolysis from 87.0–89.0 mol% to a fully hydrolysed range of 98–99 mol% has a larger effect on solubility and crystallinity than a moderate molecular weight change.
For film and barrier applications, the partially hydrolysed nature of SELVOL 818 reduces the crystalline fraction after drying and therefore lowers oxygen barrier performance relative to fully hydrolysed polyvinyl alcohol films. Barrier data for PVOH films are typically generated at 23 °C and 50 % relative humidity; under these conditions, oxygen transmission rate values are heavily dependent on plasticiser content, draw ratio, and moisture conditioning. Tensile properties can be measured according to ASTM D882 for films or ISO 527-3 for sheet; typical film formulations based on SELVOL 818 exhibit yielding behaviour that shifts to a more elastomeric response when 10–25 wt% plasticiser such as glycerol or sorbitol is incorporated. The use of a plasticiser above 25 wt% is not generally recommended because phase separation and surface exudation can occur under high-humidity storage. If the end use requires high humidity exposure above 80 % RH, a fully hydrolysed grade or additional crosslinking should be evaluated.
Thermal processing of SELVOL 818 without plasticiser is constrained by the onset of thermal degradation near 200 °C. In melt extrusion, partially hydrolysed PVOH is commonly plasticised with glycerol, sorbitol, or a polyether polyol at loadings from 15–30 wt% to lower the processing temperature. A corotating twin-screw extruder with an L/D ratio of at least 30:1 and a temperature profile of 160–190 °C is typical for compounding. Extended residence time above 220 °C should be avoided because discoloration and crosslinked gel formation can arise from elimination and oxidation reactions. The exact residence-time limit depends on screw speed, fill ratio, and vent pressure; published data for this specific configuration is limited, and production trials should be conducted with a time-resolved sampling plan to establish the onset of yellowing and torque instability. For aqueous solution processing, thermal exposure above 90 °C over prolonged hold periods can cause viscosity drift through polymer chain scission and should be monitored by in-line viscometry.
Borate crosslinking is an additional converting-line variable when SELVOL 818 is used in aqueous adhesive or gel systems. The reaction between borate ions and pendant hydroxyl groups of the polyvinyl alcohol chain produces a reversible network that increases viscosity and imparts tack. Metering of borax solution must be controlled because the viscosity response is nonlinear and can shift from a pumpable solution to a structured gel over a narrow addition range. The exact gelation threshold depends on the solids content of the PVOH solution, temperature, and degree of hydrolysis. For a solution containing 10 wt% SELVOL 818, borax addition should be introduced slowly with continuous pH monitoring; pH values above 8.0 can reduce the reversibility of the network and produce a stringy, difficult-to-clean system. In-line viscometry at 25 °C is preferred to batch grab sampling because the reaction reaches a new equilibrium rapidly after mixing.
Regulatory references commonly applied to SELVOL 818 in food-contact adhesives and coatings include FDA 21 CFR 177.1670 for polyvinyl alcohol and FDA 21 CFR 175.105 for adhesive components. Industrial compliance verification typically also addresses REACH Regulation (EC) No 1907/2006 and, for electrical and electronic product applications, RoHS Directive 2011/65/EU. Residual methanol and vinyl acetate monomer levels are relevant where food-contact or pharmaceutical packaging is manufactured. The product should not be combined with amine-based additives without compatibility testing because alkaline hydrolysis or transesterification can shift the effective degree of hydrolysis and alter solubility, film strength, and adhesive wet tack.
| Parameter | Reference method | Control purpose |
|---|---|---|
| 4 % solution viscosity | ISO 12058-1 / ASTM D2196 | Molecular weight and processing consistency |
| Degree of hydrolysis | JIS K6726 titration | Cold-water solubility and film strength |
| pH of 4 % solution | ISO 976 / ASTM E70 | Crosslinker and formulation stability |
| Volatile content | ISO 3251 | Powder handling and storage stability |
| Ash residue | ISO 3451-1 | Inorganic contamination and clarity |
In paper sizing and remoistenable coating applications, SELVOL 818 is processed as a low-foam aqueous solution and applied by size press, rod coater, or air knife. The selection of this grade rather than a fully hydrolysed PVOH is often driven by the need for lower dissolution temperature, improved adhesion to pigmented paper surfaces, and controlled water sensitivity. The operational limitation is the lower water resistance of the dried adhesive after rewetting; if water resistance is required, a fully hydrolysed grade or a crosslinking agent such as glyoxal may be necessary. The glyoxal addition level should be limited and validated by viscosity stability testing because the aldehyde reacts with the PVOH and can produce an irreversible network during storage. Finished adhesive films should be tested for blocking resistance and wet tensile strength under defined humidity conditions, using ASTM D882 tensile geometry or TAPPI T 541 for paper-based packaging as appropriate.
