| HS Code | 821037 |
| Appearance | Clear viscous liquid |
| Colour | Colourless to light yellow |
| Odour | Slight, mild characteristic odour |
| Ph | 6.0 – 7.5 |
| Solid Content | 21% by weight |
| Density | 1.02 – 1.04 g/cm³ at 25°C |
| Viscosity | 200 – 400 mPa·s at 25°C |
| Boiling Point | Approximately 100°C |
| Freezing Point | Approximately 0°C |
| Water Solubility | Miscible / dilutable with water |
| Flammability | Non-flammable |
| Ionic Nature | Non-ionic |
As an accredited SELVOL Polyvinyl Alcohol 21-205 Solution factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 21-205 Solution is packaged in 55-gallon drums, providing a ready-to-use aqueous PVA solution for safe industrial handling. |
| Container Loading (20′ FCL) | 20′ FCL of SELVOL Polyvinyl Alcohol 21-205 Solution, packed in sealed drums on pallets, secured and braced for safe transport. |
| Shipping | SELVOL Polyvinyl Alcohol 21-205 Solution ships in sealed, corrosion-resistant containers to prevent leakage and contamination. Protect from freezing and extreme heat; store above 40°F (4°C) with adequate ventilation. Standard ground freight is typical, and shipping complies with applicable transportation regulations for non-hazardous industrial chemicals. |
| Storage | Store SELVOL Polyvinyl Alcohol 21-205 Solution in a tightly sealed container in a cool, dry, well-ventilated area, away from heat, direct sunlight, and ignition sources. Protect from freezing, as temperature extremes may affect stability. Keep away from incompatible materials such as strong oxidizers. Ensure proper labeling and segregation, and follow all local storage regulations. |
| Shelf Life | Shelf life is typically six months when stored sealed at room temperature, protected from freezing, and kept free from contamination. |
SELVOL Polyvinyl Alcohol 21-205 Solution is diluted with demineralized water to a size box concentration of 12–14 wt% active PVOH for carded cotton warp yarns and 14–16 wt% active PVOH for polyester/cotton blends. The higher-solids condition for synthetic blends is required to maintain a continuous size film over hydrophobic polyester fibre surfaces where adhesion is lower than on cotton. The size box is held at 70–80°C to keep the 87–89 mol% hydrolysed grade fully hydrated and to prevent viscosity drift at the doctor blade. The as-supplied solution is related to the powder specification limits of 21–25 mPa·s for a 4% aqueous solution at 20°C under JIS K6726. In a typical slasher line equipped with 12–16 Teflon-coated drying cans, first can surface temperature is controlled at 110–120°C and the final can at 80–90°C; this decreasing profile avoids sudden skinning of the size film and reduces end breaks during lease rod separation. Single-end yarn strength after sizing is evaluated according to ASTM D2256, and size add-on is checked gravimetrically at 8–14% dry solids for ring-spun yarn. The sized warp is compatible with enzymatic desizing using α-amylase at 0.5–1.0 g/L and wetting agent at 1–2 g/L in a continuous desizing range at 60–70°C. Production-scale experience on air-jet looms indicates that size box temperatures below 60°C produce viscosity drift and uneven add-on, while overcuring above 130°C can induce thermal crystallization in the PVOH film and reduce desizing efficiency. Terminal fabric formats include high-density poplin shirting, downproof bedding shell, and indigo-dyed denim where the size film must survive abrasion from drop wires and heald frames before weaving.
On fine paper and recycled linerboard machine lines, the supplied 21-205 solution is let down with process water to 4.0–6.0 wt% active solids and applied at a pond-type two-roll size press or a film press after base sheet formation. For woodfree copy paper, the size press formulation contains 1 part dry 21-205 active solids to 2.5–3.0 parts oxidized corn starch; the cooked starch is held at 90–95°C and the PVOH solution is added after cooling to 60–65°C to minimize thermal shock and foam. Nip load is set at 35–50 N/mm, sheet moisture before the size press is held at 6–8%, and dry pickup is typically 2.0–3.5 g/m² per side for copy paper grades and 3.5–5.0 g/m² for linerboard. Surface strength is measured by IGT pick test in accordance with ISO 3783:2006, and water absorption is controlled by Cobb testing in accordance with ISO 535:2014. At paper machine speeds of 800–1,200 m/min, bath viscosity above 200 mPa·s can cause film split instability, spitting, and misting at the nip. In inkjet topcoat primer formulations, the same grade is used at 3–5 wt% in an air-knife or bent-blade coater to improve dye fixation and reduce feathering on silica-coated substrates. For food-contact paper and paperboard converting, the regulatory status of polyvinyl alcohol must be confirmed against 21 CFR 176.170 and 21 CFR 176.180 for the intended food type, temperature, and contact duration. End products include inkjet photo paper, offset printing paper, corrugated medium with improved surface sizing, and envelope stock.
During vinyl acetate-ethylene copolymerisation in a jacketed stainless steel reactor, the partially hydrolysed grade undergoes radical abstraction at the acetate side group and becomes grafted onto the latex particle surface, creating a steric barrier that reduces creaming and viscosity drift more effectively than a fully hydrolysed grade under the same colloid charge. The aqueous phase is charged with 10–20% of the total PVOH requirement at 4–5 wt% active solids, and the remaining solution is metered into the reactor during monomer addition to reach a total of 3.0–6.0 wt% dry PVOH on total monomer. Ethylene pressure is maintained at 30–65 bar depending on the target glass transition temperature, and the reaction mass is held at 80–85°C with anchor impeller speed at 60–80 rpm. Potassium persulfate at 0.05–0.15 wt% on monomer is used as thermal initiator; for redox initiation, sodium formaldehyde sulfoxylate and tert-butyl hydroperoxide are fed separately. Production-scale batches with excessive initial PVOH charge above 25% of total colloid show higher seed-stage viscosity, reduced heat transfer coefficient, and microgel formation. In multi-batch campaigns, drift in colloid feed rate greater than ±5% has been observed to shift latex viscosity outside the specification window, so positive-displacement metering pumps with mass-flow feedback are preferred over diaphragm pumps. Finished VAE dispersion is typically specified at 55–60% solids, pH 4.5–5.5, and Brookfield viscosity of 4,000–10,000 mPa·s at 25°C measured with spindle 3 at 20 rpm according to ISO 2555:2018. Residual vinyl acetate monomer is monitored by gas chromatography after extraction. The same PVOH-colloid-stabilized dispersion can be spray-dried with additional PVOH to prepare redispersible polymer powder for cement-modified tile adhesives, where the terminal product must meet powder flowability and alkaline redispersion criteria.
Remoistenable adhesive films for envelope sealing and paper tube winding are produced by applying a pre-diluted blend of 21-205 solution and plasticizer with a wire-wound rod or engraved roll to the paper substrate, followed by forced-air drying. A representative formulation uses 100 parts dry active PVOH with 5–15 parts glycerol or sorbitol and 0.05–0.2 parts defoamer; the solution viscosity at application is adjusted to 1,500–4,000 mPa·s at 25°C using ASTM D1084 Method B for Brookfield viscosity. For high-speed envelope converting, the dry coat weight is held at 6–12 g/m² and the drying tunnel air temperature is maintained at 85–105°C to prevent bubble entrapment. The adhesive is formulated for use under 21 CFR 175.105 for food-contact adhesives when indirect food contact is intended, and the converter must verify end-use migration limits for the specific food type. In paper tube lamination, the same solution is added to a dextrin-based adhesive at 5–15 wt% active PVOH to improve wet tack on high-gloss label stock. Borax or boric acid must be excluded from the blend unless deliberate thickening is required; even 0.1 wt% borate on dry PVOH can produce a reversible di-diol complex that sharply increases viscosity and can form gel particles. Exposure of unmodified films to relative humidity above 70% can produce surface blocking; in such cases, a wax dispersion or calcium stearate is incorporated at 1–3 wt% of dry solids. Terminal products include remoistenable envelope flaps, paper cores for winding pressure-sensitive tape, and laminated paperboard for book covers.
In technical ceramic processing, the solution is introduced after dispersant addition and before spray drying at 0.5–1.5 wt% active PVOH on dry ceramic solids. For an alumina slip at 60–65 wt% solids, the dispersant sequence typically includes ammonium polyacrylate at 0.3–0.6 wt% on dry powder, with pH adjusted to 9.0–10.0 using aqueous ammonia before binder addition. The pre-diluted 21-205 solution is mixed under low-shear paddle agitation for 30–45 min to avoid air entrapment; excessive shear above 800 rpm in high-speed dispersers has been observed to generate foam that persists through pressure screening. Spray drying is carried out at inlet temperature 210–230°C and outlet temperature 100–110°C, producing press-ready granules with 5–7% moisture content. Green compact strength is measured on pressed rectangular bars using three-point flexural loading per ASTM C1161; published data for this specific ceramic composition are limited, so the exact green strength value must be validated against the particle size distribution and pressing aid package in each slip system. After binder burnout at 500–600°C over 2–4 h in an air atmosphere, the compact is sintered according to the ceramic grade. Terminal products include alumina substrates for thick-film circuits, electrical porcelain insulators, and catalyst support pellets where clean burnout and low ash residue are critical.
In gypsum-based machine-applied compounds, 21-205 solution is used as a secondary water-retention agent and stabilizer at 0.2–0.8 wt% active PVOH on dry gypsum solids. The solution is post-added after the cellulose ether has fully hydrated in the batch mixer to avoid competition for free water; field practice on twin-shaft high-shear mixers with vacuum deaeration indicates that simultaneous addition of cellulose ether and PVOH can produce a short, non-trowellable paste. The final premixed joint compound is adjusted to a Helipath Brookfield viscosity of 400,000–700,000 mPa·s at 25°C measured with a T-bar spindle at 10 rpm; this range supports airless spray application through 6–10 mm nozzles without air entrapment. The compound is evaluated for water retention and joint finishing properties according to EN 13963. In cementitious tile adhesives, the PVOH is added at 0.1–0.3 wt% on dry mix and the adhesive is tested in accordance with EN 12004. In exterior cementitious applications, the water solubility of PVOH limits long-term wet strength; therefore the grade is restricted to dry interior service unless a hydrophobic additive is used at a dosage validated by wet adhesion testing. Terminal products include ready-mixed gypsum joint compound for tapered edge plasterboard finishing and thin-bed cementitious tile adhesives for interior wall tiling.
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SELVOL Polyvinyl Alcohol 21-205 Solution is an aqueous liquid preparation of partially hydrolysed polyvinyl alcohol supplied for direct metering into water-based formulations. The base resin has a nominal degree of hydrolysis of 87.0–89.0 mol% and a 4% aqueous solution viscosity of 5.0–6.0 mPa·s at 20°C when measured under JIS K6726. The liquid grade is controlled for nonvolatile fraction, pH, and flow profile; the as-supplied stream is pseudoplastic, so viscosity data are meaningful only when spindle, rotational speed, and thermal equilibration are stated. In the undiluted state the product is not a simple Newtonian fluid, and viscosity values should not be compared with dry-resin 4% viscosity unless the concentration is reduced to the same nonvolatile basis.
| Property | Value | Test method |
|---|---|---|
| Nonvolatile content | 20.5–22.5 mass % | JIS K6726 |
| pH as supplied | 4.5–6.5 | JIS K6726 |
| Base resin degree of hydrolysis | 87.0–89.0 mol% | JIS K6726 |
| Base resin 4% viscosity at 20°C | 5.0–6.0 mPa·s | JIS K6726 |
| As-supplied Brookfield viscosity | Batch-specific and shear-rate dependent | ASTM D2196-20 Method A |
Heating the liquid to 40–50°C reduces line pressure and improves transfer; prolonged exposure above 70°C in open tanks increases water loss and can produce a surface skin. Storage should be in closed high-density polyethylene or stainless steel vessels at 5–40°C. Freeze-thaw cycles may create local polymer-rich phases; if freezing occurs, the container is warmed slowly to 30–40°C with low-speed agitation until homogeneity returns. On production lines drawing from 1,000 L intermediate bulk containers, recirculation or low-shear mixing before sampling prevents stratification. Dried residue on tank walls and drum lids does not redissolve rapidly in cold water; clean-in-place requires demineralized water at 70–80°C under spray-ball action.
The liquid form eliminates the dry-resin hydration step that otherwise requires a jacketed 316L mix vessel, high-torque agitation, and a heating period of 30–60 min at 85–95°C. In dilution, demineralized water is charged first, and the 21-205 solution is added under low-shear agitation. A gate or anchor agitator operating below 60 rpm is usually sufficient for letdown; high-speed dispersers above 500 rpm can generate stable foam because the partially hydrolysed polymer lowers surface tension. Vacuum deaeration or a compatible non-silicone defoamer at 0.05–0.20 mass % of the total batch may be required in closed mixing systems. Filtration through 150–250 µm screens removes gel specks and incidental debris.
Positive-displacement pumps are preferred for transfer. Progressive cavity or diaphragm pumps with open clearances maintain stable delivery without excessive local heating; tight-clearance centrifugal pumps can raise temperature and reduce viscosity reversibly but are not appropriate for high-viscosity drum discharge. Dilute storage tanks without preservative can show microorganism growth after 48 h at 20–30°C; validated biocide treatment or use within one production shift is required. Cleaning with concentrated sodium hydroxide should be followed by a demineralized water rinse because alkaline conditions accelerate ester hydrolysis and shift viscosity downward. The product should not be mixed with concentrated mineral acids, strong oxidizers such as hypochlorite, or high levels of sulfate and phosphate salts; these can hydrolyse, oxidise, or salt out the polymer.
In remoistenable adhesives for envelopes, labels, and paper wraps, the partially hydrolysed structure supplies hydroxy groups for hydrogen bonding to cellulose while residual acetate groups impede crystallite formation. The solution is commonly diluted to 10–15 mass % nonvolatile before rod, gravure, or slot-die coating; wet film thickness is typically 60–100 µm depending on substrate porosity and line speed. The low-to-moderate molecular weight of the base resin favours rapid cold-water re-dissolution, but tack development after rewetting is a function of coat weight, residual moisture, and paper absorbency rather than a universal constant. Glycerol or sorbitol addition at 1–5 parts per hundred resin reduces film brittleness and increases open time; tensile properties measured on cast film according to ASTM D882-18 decline as plasticizer concentration increases. At relative humidity above 60%, coated stacks can block unless interleaved or stored below 30°C.
Compared with a fully hydrolysed grade such as SELVOL 103, the 21-205 film has lower equilibrium crystallinity and faster cold-water re-dissolution but lower dry-film strength under humid conditions. Compared with dry SELVOL 205 resin, the aqueous delivery form removes hot dissolution and lumping risk, but introduces water freight, microbial preservation considerations, and a higher as-supplied handling viscosity.
In surface sizing of paper and board, the solution is diluted to 5–10 mass % solids and applied at a size press or film coater. The partially hydrolysed PVOH penetrates surface pores and hydrogen-bonds with cellulose; the low-to-moderate molecular weight yields lower Brookfield viscosity at the size press than higher molecular weight PVOH grades, which can allow higher machine speed without excessive misting. When starch is coapplied, the PVOH-to-starch ratio is commonly set between 1:10 and 1:5 on a dry basis, but the exact ratio is adjusted according to base-sheet porosity, stock sizing, and pre-drying conditions. No universal addition level is assigned because surface strength is batch-dependent.
In emulsion polymerisation of vinyl acetate and vinyl acetate-ethylene copolymers, the solution is metered into the aqueous phase before monomer feed begins. The partially hydrolysed PVOH adsorbs at the oil/water interface during particle nucleation; the base-resin molecular weight influences final latex viscosity and shear stability. Production reactors operating at 50–80°C typically receive the PVOH solution at 5–15 mass % of monomer mass. The residual acetate content of 11–13 mol% provides colloidal protection but does not produce the same water resistance as fully hydrolysed grades. Particle size and coagulum are monitored by laser diffraction under ISO 22412:2017 and by filtration through 150 µm screens. In comparison with SELVOL 103, the partial hydrolysis of 21-205 gives better particle-size control in vinyl acetate homopolymerisation and reduces reactor coagulum on baffles and cooling coils when the initiator feed profile is staged. In comparison with dry SELVOL 205, the solution prevents undissolved gel specks that can seed micro-coagulum, but the water content must be included in the batch heat balance.
| Parameter | SELVOL 21-205 Solution | SELVOL 205 | SELVOL 103 |
|---|---|---|---|
| Physical form | Aqueous liquid | Dry resin | Dry resin |
| Hydrolysis | 87.0–89.0 mol% | 87.0–89.0 mol% | 98.0–99.0 mol% |
| 4% solution viscosity at 20°C | 5.0–6.0 mPa·s after dilution | 5.0–6.0 mPa·s | 3.5–4.5 mPa·s |
| Dissolution requirement | None; dilute under agitation | Hot-water cook at 85–95°C | Hot-water cook at 85–95°C |
| Typical use | Paper adhesives, emulsion polymerisation, film casting | Adhesives, paper sizing, textile size | Water-resistant coatings, high-crystallinity film |
Solution-cast film made from 21-205 is normally formulated with a plasticizer and, for structural applications, blended with a higher molecular weight PVOH grade. The base resin alone produces film with limited extensibility and pronounced moisture sensitivity; published data for this specific formulation configuration is limited, so film properties should be established on the target production line using ASTM D882-18 for tensile modulus and elongation, and ASTM E96/E96M-22 for water vapour transmission. Drying on a chill-roll or steel-belt caster commonly uses air temperatures of 80–110°C and roll surface temperatures of 20–40°C. Residual moisture above 8–10 mass % causes blocking and reduces the effective glass transition temperature sufficiently to create reel-up defects. Wound film stored above 50% relative humidity and above 30°C shows increased blocking risk. Borate-based crosslinkers may be added to wet-state coatings for tack and viscosity control; above the formulation-specific threshold, the solution gels and cannot be pumped.
The partial hydrolysis of 21-205 is the dominant control point. Residual acetate groups lower crystallisation and allow lower-temperature dissolution compared with 98–99 mol% hydrolysed grades, but they also increase equilibrium moisture uptake and reduce dry-film strength under humid conditions. A shift of 0.5 mol% within the hydrolysis specification window can change dissolution time and moisture sensitivity at the edges of the processing window. Film formulators should therefore track lot hydrolysis value and residual moisture, not just as-supplied viscosity.
Lot release should be checked against the certificate of analysis for nonvolatile content, pH, and base-resin viscosity. For food packaging adhesives and coatings, applicable regulatory references include 21 CFR 175.105 for adhesive components and 21 CFR 176.180 for paper and paperboard components in contact with food; the manufacturer should supply the current food-contact statement before use. REACH registration under Regulation 1907/2006/EC may be required for importers or formulators within the European Union. RoHS Directive 2011/65/EU applies to electrical and electronic equipment rather than the liquid polymer itself; end users must assess the final article when applicable. The product is not ISO 10993 certified for biomedical use. The final formulation must be validated under the target regulation because biocides, plasticizers, and processing aids can change the compliance profile.
Operational boundaries for the liquid grade include storage at 5–40°C in closed vessels, avoidance of freezing, and exclusion of concentrated acids, strong bases, and oxidising agents. Acid-catalysed hydrolysis lowers molecular weight and viscosity, while high levels of borate, sulfate, or phosphate salts can gel or precipitate the solution. Unpreserved dilute tanks should be used within a production shift or subjected to validated biocide treatment. When the product is diluted below 5 mass %, microbial growth potential increases sharply, and the lower viscosity no longer provides the same mixing stability as the as-supplied solution.
