| HS Code | 199474 |
| Product Name | KURARAY POVAL 40-88 LV |
| Chemical Family | Partially hydrolyzed polyvinyl alcohol (PVOH) |
| Cas Number | 9002-89-5 |
| Appearance | White granular powder |
| Degree Of Hydrolysis | 87.0 - 89.0 mol% |
| Viscosity 4 Aqueous Solution At 20 C | 38 - 43 mPa·s |
| Ph 4 Aqueous Solution | 5.5 - 7.0 |
| Solubility | Soluble in hot water; practically insoluble in cold organic solvents |
| Volatile Content | ≤ 5% |
| Ash Content | ≤ 0.5% |
| Bulk Density | Approx. 0.5 - 0.7 g/cm³ |
As an accredited KURARAY POVAL 40-88 LV factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Kuraray POVAL 40-88 LV is packaged in 25 kg multiwall paper bags with a polyethylene liner, ensuring safe, dry handling and storage. |
| Container Loading (20′ FCL) | Load 20′ FCL with palletized KURARAY POVAL 40-88 LV bags, secure properly, protect from moisture and contamination during transit. |
| Shipping | KURARAY POVAL 40-88 LV is a polyvinyl alcohol powder supplied in sealed multi-layer paper bags or fiber drums. Non-hazardous per transport regulations. Ship dry, protected from moisture and humidity. Store in ventilated area, away from heat sources. Avoid dust generation during handling and transport. |
| Storage | Store in a cool, dry, well-ventilated area away from heat, open flames, and direct sunlight. Keep containers tightly closed to prevent moisture absorption and contamination. Avoid generating dust; use appropriate ventilation. Ensure area is clean and free of incompatible materials. Under proper storage conditions, shelf life is typically stable for several years. |
| Shelf Life | Shelf life is approximately 2 years when stored in original, unopened containers in a cool, dry place. |
In vinyl acetate–ethylene and vinyl acetate–VeoVa copolymerisation, the protective colloid is introduced not as an inert thickener but as a partially hydrolysed PVOH whose residual acetate groups participate in radical chain transfer and interfacial grafting. The grade release specification is 40–46 mPa·s measured as a 4 wt% aqueous solution at 20 °C by DIN 53015, with hydrolysis between 86.5 and 89.0 mol%. This hydrolysis band maintains cold-water solubility while retaining a measurable acetate fraction that influences particle nucleation at the aqueous phase boundary; fully hydrolysed PVOH does not provide the same balance of surface tension reduction and graft stability in ethylene-containing recipes.
Formulation addition ratio is set at 3.0–6.0 wt% based on total monomer, after the grade is dissolved in a separate vessel at 10–15 wt% solids and 60–70 °C. The aqueous solution is transferred to a jacketed pressure reactor equipped with a turbine impeller; ethylene saturation is maintained between 10 and 70 bar depending on target glass transition and carboxylation level. Initiation is established by a redox pair at 55–85 °C, with monomer feed staged to avoid exotherm spikes above 5 K per minute. After polymerisation, residual monomer is stripped at 60–70 °C and 200–400 mbar before defoamer addition. On multi-reactor lines, the dominant field failure mode is filter plugging in the discharge pump when the PVOH feed solution falls below 50 °C and develops surface skin; holding the let-down vessel at 60 °C with gentle agitation reduces gel formation. Published data for this specific grade in high-shear styrene-acrylic hybrid reactors is limited, and pilot-scale determination of coagulum threshold is required before plant transfer.
Compliance for the finished VAE dispersion in construction adhesive applications is benchmarked under EN 204:2016 D2/D3 with bond strength tested according to EN 205:2016. Where the dried film enters food-contact packaging adhesives, 21 CFR 175.105 applies, and EU 10/2011 overall migration must not exceed 10 mg/dm² for the final laminate. Terminal articles made from the emulsion include carpet backcoating compounds, nonwoven binders, paper-to-film laminating adhesives, and polymer-modified cementitious tile adhesive intermediates.
A two-roll metering size press on clay-coated linerboard represents the last aqueous application point where film-forming PVOH can be deposited before the dryer section locks surface porosity. Bath concentration of 40-88 LV is set between 0.8 and 2.5 wt%, commonly in combination with thermally oxidised starch at 4–8 wt%; the ratio shifts pick-up, oil hold-out, and surface strength on release base and coated board. Operation is performed at sheet moisture 6–10 %, roll nip load 20–50 kN/m, and bath temperature 55–70 °C. Excessive pre-dryer moisture above 12 % lowers starch–PVOH co-binder retention and increases Cobb water absorptiveness measured under ISO 535:2014. Recycled furnish may introduce borate ions that interact with the 88 mol% PVOH and produce a steep viscosity rise in the starch–PVOH co-binder; pH is maintained below 7.5 and acid-stable starch derivatives are preferred to prevent gelation in the holding tray.
Compliance for food-contact paper and board is established under 21 CFR 176.170 and 176.180, with EU Framework Regulation 1935/2004 applying to final articles placed on the European market. Surface strength is monitored by IGT pick resistance in accordance with ISO 3783:2006. Terminal finished products include release liner base, folding carton board, silicone coating base stock, inkjet pigment-coated paper, and adhesive-coated tape backing.
| Standard or regulation | Scope | Applied condition |
|---|---|---|
| 21 CFR 176.170 / 176.180 | Components for paper and paperboard in dry and aqueous food contact | PVOH level controlled by GMP; no physical migration above analytical detection |
| EU 1935/2004 | Food-contact materials framework | Finished paperboard must not transfer constituents in quantities harmful to human health |
| ISO 535:2014 | Cobb water absorptiveness | Release base target set on product-specific specification |
| ISO 3783:2006 | IGT pick resistance | Minimum pick velocity depends on coat weight and furnish |
Because 40-88 LV dissolves at 60–80 °C into agitated water with low dusting, it can be compounded directly into cold-water-adjustable packaging adhesives without a separate cook kettle. Addition ratio is 4–12 wt% dry solids in the final adhesive, with plasticiser such as glycerol or sorbitol at 5–15 wt% on PVOH to regulate set time and film flexibility. Production is executed in a planetary dissolver or Z-blade mixer: the vessel is charged with cold water, dry powder is drawn in under low-speed agitation, and the jacket is heated to 85 °C for 30–60 min. Vacuum deaeration at -0.8 bar removes entrained air that would otherwise reduce adhesive transfer to high-speed corrugated and tube winding lines. Food-contact joints in dry food packaging are assessed under 21 CFR 175.105; if the adhesive is used on printed paperboard in contact with dry food, compliance with EU 10/2011 and German BfR XXXVI is verified using the manufacturer’s supporting declaration. Borated additives must be handled as a separate dilution: boric acid above 0.3 wt% of liquid adhesive produces a sharp viscosity inflection due to crosslinking with the PVOH, and addition is made under torque monitoring to avoid motor overload. Terminal finished products include paper cores, spiral-wound tubes, edge protectors, paperboard partition strips, and corrugated display units.
Slip preparation for oxide ceramic green tape begins with planetary ball milling of alumina or zirconia powder at 50–60 wt% solids, with a polyelectrolyte dispersant at 0.5–1.5 wt% and 40-88 LV binder at 1.5–4.0 wt% of dry ceramic powder. The grade enters the slip as a 5–8 wt% aqueous solution to avoid binder-rich agglomerates during milling; slip viscosity is adjusted to 4,000–8,000 mPa·s at 10 s⁻¹ before deairing. Doctor blade gap is set to 0.1–0.5 mm, with carrier film speed 0.5–2.0 m/min and drying at 25–40 °C to prevent skin-over. Binder burnout is evaluated by thermogravimetric analysis under ASTM E1131; residual ash after firing is typically below 0.5 wt%, but published data for this specific grade in tape casting is limited and must be confirmed on the target powder because alumina surface acidity shifts PVOH decomposition. Fired components are assessed for heavy metal residues under RoHS 2011/65/EU when used in electronic substrates. Terminal finished products include alumina substrates, zirconia gas sensor elements, LTCC multilayer interconnects, and green machining blanks.
On slasher lines running woven cotton or polyester/cotton greige, the PVOH content is set at 7–12 wt% relative to liquid size, combined with starch or acrylic co-binder depending on yarn type. The formulation is cooked in a jet cooker at 110–130 °C and transferred to a slasher where squeeze nip pressure is held between 0.4 and 0.8 MPa; drying cylinder temperature is profiled from 90 °C at entry to 140 °C at exit to avoid surface skinning and ends sticking. Compliance in textile processing is documented against Oeko-Tex Standard 100 Annex 4 and ZDHC MRSL v3.1; effluent from desizing must meet site COD limits. Desizing limitation: because the 88 mol% hydrolysis level retains acetate residues, low-temperature amylase treatment at 50–60 °C does not fully remove the PVOH; an alkaline wash at 70–90 °C or oxidative desizing stage is required before bleaching. Terminal finished products are woven cotton, polyester/cotton greige, and technical weaving for coated fabric operations.
Cementitious tile adhesive dry mixes containing 40-88 LV are compounded in a ploughshare or single-shaft ribbon mixer, with the PVOH powder added at 0.3–1.5 wt% of total dry mix to improve open time and adhesion to low-porosity substrates. Site water demand is set between 0.22 and 0.30 L/kg; after mixing, the mortar is rested for 5–10 min and remixed to allow full hydration of the polymer fraction. C2 classification under EN 12004:2017 requires tensile adhesion strength of at least 1.0 N/mm² after water immersion, with test methods under ISO 13007-2:2013. At addition above 1.5 wt%, open time increases but 28-day compressive strength may decline due to film softening in wet cure; published data for this specific grade in cementitious tile adhesive is limited, so a plant-scale calibration is required before C2TE production. Terminal products include C2 and C2TE cementitious tile adhesives, skim coats, and polymer-modified patching compounds.
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KURARAY POVAL 40-88 LV is a partially hydrolysed polyvinyl alcohol (PVOH/PVA) resin with a specified viscosity of 38.0–42.0 mPa·s for a 4% aqueous solution at 20°C and a degree of hydrolysis of 86.7–88.7 mol%. The grade is supplied as a granular solid for use as a temporary binder, protective colloid, film former, and sizing agent. The first numeral in the grade code denotes the nominal viscosity of 40 mPa·s; the second numeral denotes the nominal hydrolysis level of 88 mol%. The “LV” designation indicates a controlled low-volatile and reduced-residue variant, intended for processes where methanol, acetate salts, or ash carryover must be minimised. Typical applications include emulsion polymerisation stabilisation, remoistenable adhesive converting, ceramic green tape binding, paper surface sizing, textile warp sizing, and water-soluble packaging components. In the standard property table published by the manufacturer, viscosity is determined by DIN 53015, hydrolysis by JIS K6726, ash by ISO 15023-2, and volatiles by internal gravimetric procedure. Ash is specified at ≤0.5% and volatile matter at ≤5.0%; pH of a 4% aqueous solution is typically 4.5–7.0.
KURARAY POVAL uses a two-number grade code followed by a process suffix. The first number is the nominal dynamic viscosity of a 4% aqueous solution at 20°C; the second number is the nominal degree of hydrolysis in mol%. In 40-88 LV, the polymer is therefore high-molecular-weight and partially hydrolysed. The LV suffix does not alter the viscosity-hydrolysis matrix. It denotes a finishing route that lowers residual monomer, methanol, and ash. Compared with lower-viscosity partially hydrolysed grades such as 18-88, the 40-88 LV grade has higher solution viscosity at equal solids, higher dried film tensile strength, and higher open time. Compared with fully hydrolysed grades such as 40-98, the 88 mol% hydrolysis level reduces crystallinity and permits cold-water solubility, but it also lowers moisture-barrier performance and tensile modulus. A comparative framework is presented in the table below.
| Parameter | Value or range | Test procedure |
|---|---|---|
| Viscosity, 4% aqueous, 20°C | 38.0–42.0 mPa·s | DIN 53015 |
| Degree of hydrolysis | 86.7–88.7 mol% | JIS K6726 |
| Ash | ≤0.5% | ISO 15023-2 |
| Volatile matter | ≤5.0% | Manufacturer method |
| pH, 4% solution | 4.5–7.0 | ISO 15023-2 |
The physical form is a free-flowing powder with bulk density typically between 0.4 g/cm³ and 0.6 g/cm³; bulk density should be confirmed because storage compaction affects hopper discharge. The dissolution rate is influenced by particle size distribution and residual moisture. Material exposed to relative humidity above 60% may absorb water and form lumps; pre-drying is required if the resin has been stored open.
The residual 12 mol% acetate groups on the polymer backbone interrupt interchain hydrogen bonding and reduce crystalline order. This allows molecular dispersions to form in water at 20–30°C, whereas fully hydrolysed 98 mol% grades must be heated above 80°C for full dissolution. In a jacketed stainless steel vessel with a side-entering turbine running at 60 rpm, 40-88 LV is slurried into cold water at 20–25°C. The slurry is then heated to 85–90°C for 30–45 min, cooled to 20°C, and deaerated before viscosity measurement. Direct steam injection should not be used: localised overheating forms gel skins that are difficult to remove without filtration. High-shear rotor-stator dispersion is unnecessary for this grade and may entrain air. At concentrations above 10%, the solution is shear-thinning; Brookfield readings are stable only after cooling and bubble removal. Filtration through 100-mesh screens is recommended before coating or casting. The solution pH window for storage is 4.5–7.0; acidic or alkaline conditions catalyse hydrolysis or condensation reactions that shift viscosity over time.
At 88 mol% hydrolysis, the film has lower tensile strength and lower water resistance than a fully hydrolysed grade. If a water-resistant bond is required, the polymer is crosslinked with glyoxal, zirconium complexes, or melamine-formaldehyde resins, or it is blended with fully hydrolysed PVA. The degree of hydrolysis also influences surfactant compatibility and foam stability; residual acetate groups lower interfacial tension and may increase foam during colloid preparation.
| Property | 40-88 LV | 18-88 | 40-98 |
|---|---|---|---|
| Nominal viscosity, 4%, 20°C | 38.0–42.0 mPa·s | 17.0–19.0 mPa·s | 38.0–42.0 mPa·s |
| Degree of hydrolysis | 86.7–88.7 mol% | 86.7–88.7 mol% | 98.0–99.0 mol% |
| Cold-water solubility | Partial to complete at 20–30°C | Complete at 20–30°C | Requires heating above 80°C |
| Relative film tensile strength | Intermediate | Lower | Higher |
| Relative water resistance | Lower | Lower | Higher |
| Ash specification | ≤0.5%, LV-controlled | ≤0.5% | ≤0.5% |
In remoistenable adhesive converting and paper sizing, 40-88 LV is applied at 8–20% solids by roll coater or knife coater. The high molecular weight increases cohesive strength and open time relative to 18-88, but it also increases drying load and pan viscosity. On a production coater running at 150 m/min with a dry coat weight of 1.0 g/m², the coating pan is maintained below 30°C to prevent surface skinning, and return lines are sized for low-shear laminar flow to avoid shear-induced insolubles. Peel adhesion on kraft paper is commonly assessed by ASTM D1876; published data for this specific grade and coat weight are limited, so pilot coating trials with the intended substrate are required. 40-88 LV generally provides greater fibre-tear adhesion on porous corrugating media than 18-88, but it flows less readily into narrow flute profiles unless solids are lowered or the coat weight is reduced.
For paper surface sizing, 40-88 LV is blended with starch or styrene-acrylic emulsion at 0.5–2.0% PVA solids. The partially hydrolysed structure contributes film flexibility and reduces dusting on lightweight calendered grades. Size-press viscosity rises sharply with concentration; inline dilution and real-time viscosity measurement are used because the 40 mPa·s base viscosity creates a steep concentration-viscosity curve. If the starch cooker operates above 95°C, the PVA stream is added after cooling; extended high-temperature residence in the presence of amylase enzymes can degrade the polymer and reduce surface strength.
Substitution of 40-88 LV for 18-88 or 26-88 in vinyl acetate emulsion polymerisation changes both reactor rheology and final latex particle-size distribution. The higher molecular weight of the protective colloid increases grafting efficiency and raises the viscosity contribution per unit solids. In a stirred tank polymerisation vessel with an anchor agitator, replacement at equal addition level typically produces a coarser final particle-size distribution and higher latex Brookfield viscosity at equivalent solids. Process adjustments include reducing the initial charge of 40-88 LV by 10–20% relative to the lower-viscosity grade or adding the polymer as a delayed aqueous solution after the nucleation period. The degree of polymerisation of the polyvinyl alcohol also affects the shear stability of the resulting latex; 40-88 LV imparts higher mechanical stability than lower-viscosity protective colloids but reduces spray-dryer throughput because of the higher feed viscosity. Latex viscosity is measured by ISO 2555 at 20°C; product specifications should be re-established after any protective colloid substitution because final coagulum and residue on 100-mesh screens may shift.
The partially hydrolysed acetate content of 40-88 LV is compatible with anionic and nonionic surfactants used in emulsion polymerisation. It is less effective as a steric stabiliser for highly hydrophobic monomers than fully hydrolysed grades; for vinyl acetate-ethylene copolymerisation at ethylene pressures above 10 bar, blends with fully hydrolysed PVA or cellulosic stabilisers are commonly used. Residual methanol in the LV grade is controlled, which reduces volatile organic compound contribution during latex stripping. For food-contact emulsion adhesives, regulatory assessment is typically made under FDA 21 CFR 175.105; for paper and paperboard contact, FDA 21 CFR 176.170 may apply depending on the final structure.
In tape casting of alumina and barium titanate slurries, polyvinyl alcohol functions as the primary binder. Slurries are formulated with 3–6 wt% PVOH on dry ceramic powder, plasticised with glycerol or polyethylene glycol, and cast onto a silicone-coated carrier. 40-88 LV is selected for this application because its high molecular weight improves green strength after drying. Green tape tensile strength is measured by ASTM D882; actual values depend on ceramic loading, plasticiser ratio, and residual solvent. The low ash specification of the LV variant reduces the risk of sodium, calcium, and iron contamination in fired dielectric layers. Sintering burnout is typically conducted in air between 350°C and 450°C; residual carbon and inorganic ash are influenced by heating rate and oxygen flow. Fully hydrolysed grades leave higher sodium content unless specially washed; partially hydrolysed 40-88 LV offers a lower cold-water dissolution temperature and lower solution viscosity at equivalent solids, which shortens slurry ageing time.
In multilayer ceramic capacitor lines, lot-to-lot ash variation in the binder is a critical control point. The LV designation is intended to reduce this variation, but each lot should be checked for Na2O and Fe2O3 against the approved specification. Slurry prepared with 40-88 LV may require a two-stage deaeration cycle because the high-molecular-weight solution retains entrained air. Degassing under 0.2 bar absolute for 30 min is common before casting; air bubbles larger than 20 µm produce pinholes in green tape. Thermogravimetric analysis of the polymer shows the main decomposition onset under air at approximately 280–300°C, with oxidative burnout complete by 450°C at a heating rate of 5 K/min.
Cast films of 40-88 LV are transparent but exhibit lower tensile strength and higher elongation than films of fully hydrolysed grades. When dried from 10% solution at 80°C, the film can absorb moisture at relative humidity above 60%, which plasticises the matrix and reduces modulus. For water-soluble packaging or detergent pouches, this moisture sensitivity is an advantage but requires sealing and storage in low-humidity conditions. The polymer may be blended with plasticisers such as glycerol or sorbitol at 5–15% on dry resin to adjust tear propagation and seal temperature. Because the molecular weight is high, plasticiser migration to the surface is slower than in lower-viscosity grades, but elevated storage temperature accelerates it. Film property data are typically generated by ASTM D882 or ISO 527-3; values are not intrinsic and depend on sample preparation and conditioning at 23°C and 50% RH.
The powder is combustible as an airborne dust. Pneumatic conveying lines must be grounded, and dust collectors should be explosion vented. Moisture uptake is rapid above 60% RH; open bags can absorb more than 2% water within 24 h. If the resin has been exposed to humid air, it is dried at 60–80°C for 2–4 h before dry blending or melt processing. Aqueous solutions of 40-88 LV support microbial growth after 48 h at 20–30°C; storage tanks and recirculation lines should be cleaned with hot water and alkali or protected with a biocide. The polymer should not be mixed with strong oxidising agents. In batch make-up, the powder is added to the vortex in cold water; adding water to dry powder creates lumps that require extended heating and filtration.
Regulatory classification under REACH does not identify this polymer as a hazardous substance, but the supplier safety data sheet and lot certificate remain the authoritative documents for specific impurities and residual solvents. For electrical and electronic applications, heavy-metal restrictions are typically addressed by conformity to RoHS where the final article is in scope. In food-contact adhesive applications, clearance is generally established under FDA 21 CFR 175.105; in paper and paperboard coatings, FDA 21 CFR 176.170 may apply. Migration tests must be run on the finished article because compliance is formulation- and coat-weight-dependent. The operational envelope of 40-88 LV is most constrained by solution viscosity, moisture sensitivity, and lot-specific ash content. Processes that can tolerate these constraints and require the combination of high molecular weight with partial hydrolysis use this grade as a building block in adhesive, ceramic, polymerisation, and water-soluble film systems.
