| HS Code | 484928 |
| Product Name | SELVOL Polyvinyl Alcohol 840 |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White powder |
| Hydrolysis Degree | 87-89 mol% (partially hydrolyzed) |
| Viscosity 4 Solution At 20 C | 14-18 mPa·s |
| Ph 4 Solution | 5.0-7.0 |
| Ash Content | ≤ 0.5% |
| Volatile Content | ≤ 5.0% |
| Specific Gravity | 1.27 |
| Melting Point | 180-190°C |
| Solubility | Soluble in hot water; insoluble in common organic solvents |
As an accredited SELVOL Polyvinyl Alcohol 840 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 840 is a white powdered resin supplied in 25 kg multiwall paper bags, ensuring safe handling and storage. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with SELVOL Polyvinyl Alcohol 840, packed securely on pallets, ready for safe transport. |
| Shipping | SELVOL Polyvinyl Alcohol 840 ships as a dry, free-flowing powder in sealed bags or containers. Protect from moisture, humidity, and direct contact with water to prevent clumping or dissolution. Store in a cool, dry, well-ventilated area. No special hazardous designation required, but use standard industrial hygiene practices. |
| Storage | Store in a cool, dry, well-ventilated area away from heat, sparks, and open flames. Keep the container tightly closed when not in use to prevent moisture absorption. Avoid generating dust and keep away from strong oxidizers and incompatible materials. Ensure proper labeling and segregation in a clean, dry environment. |
| Shelf Life | Shelf life is typically two years from shipment when stored in original, unopened containers in a cool, dry area. |
SELVOL Polyvinyl Alcohol 840 is a partially hydrolysed polyvinyl alcohol with hydrolysis of 86.0–89.0 mol% and a 4% aqueous solution viscosity of 43–52 cP at 20 °C. The applications that follow are limited to industrial processes for which the grade is used in production: emulsion polymerization, water-based packaging adhesives, paper surface sizing, water-soluble film, textile warp sizing, and ceramic green body binding. Data are stated as operational ranges referenced to standard test methods or production practice; published data for this specific grade in some niche configurations is limited.
In vinyl acetate homopolymer and vinyl acetate/ethylene emulsion polymerisation, SELVOL Polyvinyl Alcohol 840 is charged as a protective colloid at 3–7 parts per 100 parts vinyl acetate monomer. The lower limit is set by colloid starvation: below 3 phm reactor fouling on baffles and thermowells increases, and coagulum retention on 45 µm screen packs rises within the first 2 h of monomer feed. The upper limit above 7 phm is governed by final latex rheology; low-shear viscosity can exceed 30 000 mPa·s at 25 °C, creating transfer difficulties in large holding tanks and reducing high-shear processability in downstream coating. The polymerisation is conducted in a jacketed stainless-steel reactor at 70–80 °C using sodium persulfate or a persulfate/redox initiator system and a sodium bicarbonate buffer at pH 4.0–5.0. Agitation with a pitched-blade turbine at 180–250 rpm maintains monomer dispersion; lower agitation produces vinyl acetate pooling and uncontrolled exotherms, while higher shear can strip the grafted colloid layer from growing particles. During polymerisation, polyvinyl acetate grafts onto the PVOH backbone through chain transfer to the methine position, yielding a graft copolymer that controls particle size distribution and emulsion stability. The partially hydrolysed structure of PVOH 840 provides residual acetate sequences that anchor at the monomer-water interface; this is especially relevant in vinyl acetate/ethylene systems where ethylene pressure is maintained at 0.5–2.0 MPa and hydrophobic monomer ingress must be stabilised without excessive high-shear viscosity. The final latex is typically adjusted to 50–65% solids and pH 4.0–5.5, with residual vinyl acetate reduced below 0.5 wt% by a post-polymerisation initiator shot at 70 °C. Latex viscosity is measured by ISO 3219, solids content by ISO 3251, and sieve residue by ISO 4576. Compliance for latex used in food-contact adhesives and paper coatings is assessed under FDA 21 CFR 175.105 and FDA 21 CFR 176.170. Finished terminal products include interior architectural paints, paper-to-paper converting adhesives, nonwoven binders, and carpet backing compounds. A production limitation is that PVOH 840 solutions must be completely dissolved and filtered through 100–200 µm filter socks before charging; residual gel particles create microgrit in the latex and are detected as coarse particles on 45 µm screen retention tests.
In paper tube winding and corrugated board lamination, SELVOL Polyvinyl Alcohol 840 is formulated at 3–8 wt% of the wet adhesive, typically in combination with plasticised starch or dextrin at 5–15 wt% and glycerine or sorbitol at 0.5–2.0 wt%. The dry solids of the adhesive are held between 20% and 35%, and the Brookfield viscosity at 25 °C is adjusted to 2 000–8 000 mPa·s depending on the wet film weight required by the coated board caliper. Dissolution is carried out in a jacketed turbine mixer at 65–85 °C, followed by a hold at 80–90 °C for 30–60 min and cooling to 30–40 °C before transfer to the coating station. The adhesive is applied by roller coater or slot-die at 30–60 g/m² wet film weight, with compression at 0.2–0.5 MPa for 5–30 s depending on board absorbency and machine speed. In high-speed tube winding above 60 m/min, the PVOH 840 portion raises tack development and reduces slip after the first wind; however, at ambient relative humidity above 70%, open time can fall below 10 s because surface skinning occurs before compression, producing a weak bond at the interface. Viscosity is measured with ASTM D1084, T-peel bond strength with ASTM D1876, and adhesive film moisture sensitivity may be monitored by TAPPI T 441 Cobb tests on the bonded board. For food-contact paper packaging, the adhesive falls within FDA 21 CFR 175.105, and where the finished article is paper or paperboard, the materials are evaluated under FDA 21 CFR 176.170 or 176.180. Terminal products include spiral-wound paper cores, paper sacks, multi-wall bag seams, and beverage multipack carriers. The main process incompatibility is with borated or heavily starch-crosslinked systems below pH 5.5, where premature gelation can occur; buffering with sodium bicarbonate to pH 6.0–7.0 is common before adding PVOH 840 to the starch cook.
On recycled linerboard and testliner machines running above 900 m/min, PVOH 840 is prepared as a 4–8 wt% size-press solution and applied at 1.5–4.0 g/m² dry pickup either alone or as a 0.3–1.5 wt% component of oxidised starch. The size press is commonly a metering film press with rod or blade metering; the PVOH 840 addition lowers dynamic surface tension and improves film transfer to the sheet without the misting observed with high-molecular-weight fully hydrolysed grades. Drying after the size press is maintained at 80–120 °C cylinder surface temperatures, with after-dryer sections adjusted to avoid sheet surface temperature above 90 °C, above which surface film thermoplasticity can cause picking on the following calender stack. The sizing effect is measured by ISO 535 Cobb values; a PVOH 840 pickup of 1.5–2.0 g/m² typically reduces the 60-second Cobb value by 15–30% relative to a starch-only control, while grease resistance measured by TAPPI T 559 improves at the same pickup. For food-contact paper and paperboard, the grade can be used under FDA 21 CFR 176.170 and 176.180; EU compliance is assessed under Regulation (EC) No 10/2011 for plastic materials used in food contact, with migration testing according to EN 1186 where the final laminate is not functionally separated. Finished products include recycled linerboard, folding carton board, cupstock, and release-base papers where a dense and oil-resistant surface is required before silicone coating. The operational boundary is that PVOH 840 is not a water repellent; it increases water resistance through film closure and starch interaction, and the surface remains hydrophilic under extended water contact unless insolubilising agents such as glyoxal or ammonium zirconium carbonate are used in the size press.
The cold-water disintegration threshold of PVOH 840 is governed by its partially hydrolysed structure; film cast from a 65–80 wt% PVOH 840 compound with 10–20 parts plasticiser per 100 parts resin and 2–5 parts of a nonionic release aid begins dissolution in agitated water at 15–30 °C. The aqueous casting solution is prepared at 18–25 wt% solids, degassed under vacuum at −0.08 MPa for 30–60 min, and cast onto a chromium-plated steel belt or drum dryer at 80–110 °C. Line speed is limited by residual moisture; film exits the dryer at 6–10 wt% moisture and is wound under controlled tension to avoid blocking. Converter-side thermal sealing is performed at 140–180 °C with dwell times of 0.3–1.0 s, and the heat-seal jaws are coated with a release material to prevent polymer transfer from the partially hydrolysed surface. Pouch forming uses vertical form-fill-seal or cavity thermoforming; the film is preheated to 80–110 °C before forming into cavities, and seal area contamination by detergent powder reduces seal strength. Mechanical testing according to ASTM D882 or ISO 527-3 is used to measure tensile strength at break and elongation; typical control limits are set by the detergent converter, but published data for this specific grade in unit-dose film is limited, so incoming film lots are screened for dissolution time in 10 °C water, pinholing, and seal strength. Food-contact use of PVOH film is covered by FDA 21 CFR 177.1670 and EU Regulation (EC) No 10/2011; detergent and cleaning product packaging must additionally meet the EU Detergents Regulation (EC) No 648/2004 for labelling and composition requirements. Terminal products include water-soluble unit-dose detergent pouches and dishwasher tablet wrapping. The main incompatibility is with high oxidative actives or high concentrations of amine solvents in the filled formulation, which can accelerate chain scission and embrittlement; compatibility screening is required for peroxide-based or strongly alkaline fills.
For high-density polyester/cotton warp yarns slashed for air-jet weaving, SELVOL Polyvinyl Alcohol 840 is used at 3–8 wt% of the size liquor, often in combination with starch at 6–12 wt% total solids, and applied through a two-box slasher with squeeze roll pressure adjusted to give 8–14 wt% dry size add-on by yarn mass. The partially hydrolysed grade dissolves more readily at 70–85 °C than fully hydrolysed types, but it still requires a 30–45 min cook with agitation and filtration through 100–150 µm filters to remove undissolved fines that would deposit on the immersion roller. In air-jet weaving, the size film must resist loss by abrasion from relay nozzles and drop wires; the medium molecular weight of PVOH 840 contributes to chain entanglement and maintains size film elongation under cyclic strain, but at high loom-humidity conditions the film can plasticise and shed, increasing ends-down. Desizing is carried out in a hot water wash at 85–95 °C because the grade is water-soluble without enzymatic oxidation; residual PVOH can be monitored by chemical oxygen demand or PVA-specific analytical methods in the scouring bath. Textile formulations are placed on the market under REACH (EC) No 1907/2006 and must be checked against ZDHC MRSL v3.1; yarn tensile and elongation after sizing are assessed under ASTM D2256 or ISO 2062. Terminal products include woven apparel fabrics, workwear blends, and home textiles where a clean desize and low ash residue are required before dyeing. The operational limit is that at add-on above 14% the size film becomes brittle at low loom-humidity conditions and can crack at the drop-wire contact point.
Ceramic spray-dried powder pressing lines use PVOH 840 as a green binder at 0.5–3.0 wt% based on dry ceramic powder, added as a 5–10 wt% aqueous solution during slurry preparation. The slurry containing alumina, zirconia, or cordierite precursors is ball-milled with a polyacrylate dispersant, then spray-dried at inlet air temperature 180–220 °C and outlet temperature 70–95 °C. The grade’s residual acetate groups reduce spray-dryer shell build-up compared with fully hydrolysed grades because the dried particle surface is less brittle under cyclone impingement. Uniaxial pressing is conducted at 80–150 MPa, and the green compacts develop enough strength for green machining because the polymer bridges ceramic particles at contact points; green density is typically 55–60% of theoretical for oxide ceramics, but published data for this specific grade in advanced ceramic formulations is limited. Debinding kilns require a slow heating ramp between 300 °C and 500 °C in air or nitrogen to avoid delamination; PVOH decomposes through side-chain elimination and main-chain scission, and a heating rate above 2 °C/min can cause surface-to-interior pressure differentials that crack the green body. Fired ceramics are evaluated for compliance with RoHS Directive 2011/65/EU when used in electrical or electronic equipment, and for structural ceramics relevant ISO standards such as ISO 13356 for implant-grade zirconia or ASTM C373 for water absorption are applied. Terminal products include alumina electronic substrates, zirconia oxygen sensor components, cordierite honeycomb monoliths, and technical ceramic parts requiring binder-free porosity after sintering. The main incompatibility is with strongly acidic ceramic slurries below pH 4, where the PVOH solution can gel or precipitate in the presence of multivalent ions such as aluminium; slurry pH is therefore stabilised above 4.5 before binder addition.
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SELVOL Polyvinyl Alcohol 840 is a partially hydrolysed polyvinyl alcohol resin supplied as granular solid or powder. Material specifications reported under ISO 15023-2 place the degree of hydrolysis at 87.0–89.0 mol% and the viscosity of a 4% aqueous solution at 20 °C in the range 45–55 mPa·s. Aqueous-solution pH is controlled within 4.5–6.5, volatile content is specified at not more than 5.0%, and ash expressed as Na₂O is specified at not more than 0.7%. These values place the product in the medium-high viscosity segment of the partially hydrolysed Selvol series. Residual acetate groups reduce crystallinity relative to fully hydrolysed grades such as Selvol 103 and Selvol 107, providing lower-temperature water solubility but higher equilibrium moisture uptake and lower film water resistance. The molecular weight contribution places Selvol 840 above low-viscosity partially hydrolysed grades such as Selvol 205 in solution viscosity and cohesive strength, while retaining the same general hydrolysis window. The product is therefore selected where higher green strength, higher emulsion stabilising viscosity, or greater adhesive tack is required without moving to a fully hydrolysed grade. Film properties, solubility, and viscosity can be verified by lot-specific test certificates using ISO 15023-2 methods.
| Property | Test method | Typical specification |
|---|---|---|
| Degree of hydrolysis | ISO 15023-2 | 87.0–89.0 mol% |
| Viscosity, 4% aqueous solution at 20 °C | ISO 15023-2 falling-ball method | 45–55 mPa·s |
| pH | ISO 15023-2 | 4.5–6.5 |
| Volatile content | ISO 15023-2 | ≤5.0% |
| Ash content as Na₂O | ISO 15023-2 | ≤0.7% |
The ranges in the table are typical specification values, not substitutes for a certificate of analysis for a specific lot.
In aqueous make-down for adhesives and coatings, the resin is first dispersed in water at 20–35 °C and then heated to 85–95 °C in a jacketed vessel fitted with a turbine agitator or high-shear rotor-stator device. The 87.0–89.0 mol% hydrolysis window leaves enough residual acetate groups to suppress the strong interchain hydrogen bonding found in fully hydrolysed material, so complete dissolution is possible without caustic addition. However, the medium-high molecular weight creates a viscosity peak during the gel phase. If the powder is added as a dry slug, the particle surface hydrates into a gel skin that prevents water penetration and forms fish-eye defects. Production-scale make-down tanks from 500 L to 2000 L are typically operated with controlled powder addition through an eductor or venturi mixer, and the final solids content is held at or below 10 wt% unless a high-torque anchor agitator is available. After the temperature reaches 85–95 °C, a hold time of 30–60 min is commonly required to clear haze and reduce undissolved gel counts. Cooling to 25–40 °C then produces the final working viscosity. Failure to control the addition rate creates a processing conflict: the higher molecular weight that improves dry adhesion and film strength also increases the dissolution viscosity and extends the hydration time. The same grade will therefore require a longer make-down cycle than Selvol 205 or Selvol 523 at equal solids. The benefit is a higher final solution viscosity at equal concentration, allowing formulators to reduce binder solids without losing film strength. Plant quality control often uses a Brookfield RVT viscometer at 20 rpm with spindle No. 3 for rapid batch verification, but the reference is the falling-ball method under ISO 15023-2.
Water-based adhesives formulated with Selvol 840 are applied by rod, roll, or slot-die coaters. The higher solution viscosity of the grade relative to Selvol 523 at equal solids allows a reduction in total binder solids, which shortens drying time on thermally sensitive substrates. When applied to paper or board at coat weights from 5–15 g/m², the dry film contributes fibre-tear adhesion under TAPPI T499 or equivalent tensile adhesion tests. The partial hydrolysis level provides better cold-water re-wettability than fully hydrolysed grades, which is useful in remoistenable adhesive applications. The film remains water-sensitive in humid environments, so packaging adhesives may require a water-resistant overcoat or blending with fully hydrolysed PVOH or starch.
When Selvol 840 is applied as a remoistenable adhesive on envelope and label stock, the dried film re-wets at 20–40 °C and develops tack within 2–5 s of contact. The partially hydrolysed structure provides higher re-wet speed than fully hydrolysed grades because water enters the film more readily. The higher molecular weight relative to Selvol 205 imparts higher dry tack, but the adhesive viscosity must be controlled by dilution because the solution can exceed the operating range of high-speed roll coaters. Batch-to-batch variation in the 45–55 mPa·s reference viscosity can produce measurable viscosity differences in the final adhesive; therefore incoming lot testing under ISO 15023-2 is used to adjust dilution factors.
In vinyl acetate and vinyl acetate-ethylene emulsion polymerisation, Selvol 840 is metered into the aqueous phase as a protective colloid at concentrations from 2.0 wt% to 6.0 wt% relative to monomer. The 45–55 mPa·s solution viscosity of the 4% reference solution translates into a higher reactor-phase viscosity than lower-viscosity partially hydrolysed grades, which increases particle size stability and reduces coalescence under stirred conditions. Production reactors using retreat-curve impellers at 80–120 rpm show that selection of this grade can reduce coagulum formation, but the viscosity increase also reduces heat-transfer coefficients at the reactor jacket. The process window is therefore bounded by the need for stable particle formation at the upper end and by the need for adequate heat removal at the lower end. The residual acetate groups alter grafting efficiency with vinyl acetate and shift the distribution of stabiliser between the aqueous phase and particle surface. Published data for this specific configuration is limited in open literature; pilot-scale reactor trials are necessary to determine the optimum dosage because comonomer composition, initiator type, and agitation pattern interact with molecular weight.
Ceramic green tape casting on slot-die lines uses Selvol 840 when the binder must raise green strength without requiring a fully hydrolysed grade. Slurries compounded at 35–50 vol% barium titanate or alumina solids use the polymer solution as a binder and rheology modifier. The 45–55 mPa·s reference viscosity indicates a longer chain than lower-viscosity partially hydrolysed grades, which increases interparticle bridging and green tensile strength. The trade-off is slurry viscosity: to maintain a casting viscosity of 1500–3000 mPa·s at 100 s⁻¹, solids loading may be reduced by 1.5–2.5 percentage points compared with a Selvol 205 formulation. Tape cast from Selvol 840 exhibits lower cracking during punching and winding when residual moisture is controlled below 1.0 wt%. The ≤0.7% ash specification is critical for multilayer ceramic capacitor and thick-film dielectric applications, because inorganic residues after binder burnout can increase loss tangent and compromise insulation resistance.
On film-transfer size presses running at 40–60 m/min, Selvol 840 is blended with oxidised starch at dry ratios from 1:10 to 1:4 to increase surface strength without creating a separate water-resistant barrier. The size solution is held at 60–70 °C to control viscosity and avoid gel formation. Surface strength is assessed by IGT pick testing under ISO 3783, and the higher molecular weight of Selvol 840 can improve pick strength at equal solids compared with lower-viscosity partially hydrolysed grades. The residual hydrolysis window leaves the film water-sensitive, so it is not selected when wet-rub resistance or low Cobb values below 30 g/m² under ISO 535 are the primary requirement. In those applications, fully hydrolysed grades provide better water resistance, but their solution make-down requires higher temperature and more aggressive agitation.
On slasher ranges operating at 30–80 m/min, Selvol 840 is used in warp size formulations with modified starch and acrylic copolymer. The partial hydrolysis window permits desizing with hot water at 80 °C, eliminating enzymatic or oxidative desizing in plants that do not run cellulosic fibre blends. Compared with fully hydrolysed grades, the lower crystallinity reduces hard deposits on reeds and heddles. The film absorbs atmospheric moisture, so warp beams stored at relative humidity above 60% can develop blocking, and pre-drying of the warp sheet is required before winding. Boric acid or borate crosslinkers should be used with controlled addition, because gelation can occur rapidly and increase size-box viscosity beyond the pumping limits of conventional slasher size boxes.
Mould release films and temporary protective coatings based on Selvol 840 are typically deposited from 2.0–5.0 wt% aqueous solutions and dried at 60–80 °C. The pH specification of 4.5–6.5 and ash limit of ≤0.7% reduce the risk of interaction with acid-catalysed tooling surfaces and leave lower inorganic residue after film peeling. Films made from partially hydrolysed Selvol 840 exhibit higher elongation and lower tensile strength than films from fully hydrolysed grades, a difference that reduces brittle cracking when the film is stretched over complex mould features. The trade-off is lower water resistance, so the material is used where water rinsing after demoulding is acceptable. For epoxy or unsaturated polyester tooling, release behaviour must be tested on production surfaces under actual curing conditions, because surface energy and tooling release chemistry can dominate film performance.
The resin is hygroscopic. Storage in silos or bulk bags at relative humidity above 60% can raise volatile content and alter powder flow, leading to bridging in hoppers and variability in dissolution time. Silo discharge equipment should include dry-air sweeps or desiccant breathers, and the volatile content should be checked by ISO 15023-2 before use when storage conditions are uncontrolled. Dust-air mixtures of polyvinyl alcohol powder are combustible, so transfer lines, dust collectors, and charging stations must be grounded and provided with local exhaust ventilation. The product should not be blended with strong oxidisers or exposed to open flame. Regulatory status for food-contact use is not uniform across jurisdictions, and compliance must be confirmed for the specific article and conditions of use under FDA 21 CFR or the applicable regional legislation before that application is attempted.
