| HS Code | 471361 |
| Product Name | KURARAY POVAL 49-88 |
| Chemical Name | Polyvinyl alcohol (partially hydrolyzed) |
| Chemical Formula | (C2H4O)n |
| Cas Number | 9002-89-5 |
| Appearance | White to pale yellow granular powder |
| Degree Of Hydrolysis | 87-89 mol% (nominal 88 mol%) |
| Viscosity | 49 mPa·s (nominal; spec range 43-53) at 4% concentration in water at 20°C |
| Ph | 5.0-7.0 (4% aqueous solution) |
| Specific Gravity | 1.25-1.31 (solid at 20°C) |
| Solubility | Soluble in hot water; sparingly soluble in cold water; insoluble in common organic solvents |
| Melting Point | Approximately 180-190°C (with decomposition) |
As an accredited KURARAY POVAL 49-88 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Kuraray POVAL 49-88 is supplied as a white powder in 25 kg paper bags with a polyethylene inner liner for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with KURARAY POVAL 49-88 polyvinyl alcohol, in bags on shrink-wrapped pallets, secured and ventilated. |
| Shipping | KURARAY POVAL 49-88 is shipped as a free-flowing powder in moisture-proof multi-wall bags or fibre drums, typically 20–25 kg, with palletized shrink-wrap option. It is non-hazardous under transport regulations, but avoid dust generation. Store in dry, cool, ventilated conditions, protected from humidity and direct sunlight. |
| Storage | Store KURARAY POVAL 49-88 in a cool, dry, well-ventilated area away from direct sunlight, moisture, heat, and ignition sources. Keep containers tightly closed when not in use to prevent caking or moisture pickup. Avoid generating dust; keep away from strong oxidizers. Follow local regulations and maintain proper labeling. |
| Shelf Life | Store in a dry area, away from moisture. Shelf life is typically two years from manufacture under recommended storage conditions. |
In commercial VAE and PVAc emulsion polymerisation, Poval 49-88 functions as both a water-soluble thickener and a grafting substrate; its 87.0–89.0 mol% degree of hydrolysis and 44.0–50.0 mPa·s solution viscosity at 4% solids set the grafting density at the vinyl acetate/water interface, which in turn determines whether the final dispersion has a monomodal particle size distribution or a shear-unstable bimodal population. The standard pre-dispersion sequence starts with dissolving the grade at 85–95°C for 30–45 min, then cooling to 60–65°C before the monomer feed; residual undissolved gel particles, measured as ≤0.5 g on a 100 µm filter screen, are the main cause of microgrit in downstream transfer coating. A typical formulation for a wood adhesive dispersion conforming to EN 204/205 class D2 uses 2.0–3.5 wt% Poval 49-88 on total vinyl acetate monomer. Below 1.5 wt%, the dispersion viscosity at 55% solids drops below 4,000 mPa·s and the protective PVOH layer around the polymer particles becomes too thin to prevent coalescence during freeze-thaw cycling. Above 4.0 wt%, the carboxylated comonomer uptake becomes non-linear, the reactor pH drifts by more than 0.3 units during the first 90 min, and the dried film loses water resistance because free PVOH migrates to the bond line. The polymerisation itself is run at 60–75°C, with redox initiation permitting monomer conversion above 99% before vacuum stripping of residual vinyl acetate to <0.1 wt%. The resulting dispersion is transferred to adhesive compounding lines, where plasticisers, defoamers, and thickeners are added under high-shear mixing at 1,000–1,500 rpm. The terminal products are D2/D3 wood assembly adhesives, paper-to-paper laminating adhesives, and construction adhesives with a wet tack of 1.5–2.5 N/mm² tested according to EN 1465 on beech wood. Compliance for food-contact uses is covered by FDA 21 CFR 175.105, with the film treated as an indirect additive subject to good manufacturing practice limits; the grade is registered under REACH 1907/2006, and borate-based rheology modifiers should not be combined with this PVOH at pH above 8.0 because of premature borate ester gelation.
The decision to replace cellulose ether with Poval 49-88 as the secondary dispersant in suspension PVC becomes process-critical when the reactor targets a K-value of 66–67 and the primary dispersant holds the vinyl chloride droplets at high interfacial tension. A typical charge uses 0.05–0.12 wt% Poval 49-88 on vinyl chloride monomer, in combination with a primary PVOH of higher hydrolysis, in a stirred batch reactor of 30–60 m³ operating at 55–62°C and 0.8–1.1 MPa. At this level, the 44.0–50.0 mPa·s viscosity of the 4% solution slows drainage of the dispersant film during the pressure-drop phase, resulting in a resin with a mean particle diameter of 120–180 µm and a cold plasticizer absorption of 18–25 g DOP per 100 g resin when measured according to ASTM D3367. Below 0.03 wt%, the slurry develops fine particles below 30 µm, which raises dry powder carryover in the centrifuge and increases reactor scale on the walls. Above 0.15 wt%, the primary particles remain overstabilised, reducing the final bulk density below 0.48 g/cm³ and extending the fluidised-bed drying time beyond standard cycle limits. The downstream process is a closed reactor sequence with fresh VCM charging, hot demineralised water at 55–60°C, peroxide or azo initiator, and pressure letdown after conversion reaches 80–85%; the slurry is then passed through a degassing column and a centrifuge before flash drying. Compliance for resin classification is anchored to ASTM D1755-15, with K-value determined by ISO 1628-2. The terminal products are PVC-U pipes under EN ISO 1452-2, window profiles, and cable sheathing compounds requiring resin with consistent porosity and low gel count.
Binder migration in blade-coated inkjet base paper becomes operationally detectable when the coat weight declines below 6 g/m² and the surface pore structure shifts from micropore to mesopore distribution. Poval 49-88 is introduced into the coating colour as a 10–15 wt% aqueous solution at 2.0–6.0 dry parts per 100 pigment, typically blended with precipitated calcium carbonate or fumed silica in the topcoat. The 87.0–89.0 mol% hydrolysis level gives a lower water retention contribution than fully hydrolysed grades, making it suitable for high-speed blade coating where excessive viscosity retention would cause blade streaking at 800–1,200 m/min. The solution is prepared at 90–95°C for 20–30 min, cooled to 55–60°C, and added after the pigment slurry has been dispersed at 3,000–4,000 rpm in a high-shear mixer. During drying, the low-molecular-weight fraction of Poval 49-88 migrates toward the coating surface; the resulting dry pick resistance is evaluated by ISO 3783, and water absorption is checked by ISO 535 Cobb 60 with values held below 22 g/m² for high-speed inkjet printing. The coating colour solids are maintained at 60–66%, with pH between 8.0 and 9.5 to prevent gelling of the PVOH in the presence of calcium ions. Compliance for food-contact paper and board is within FDA 21 CFR 176.170 and FDA 21 CFR 176.180, subject to extraction limits; for non-food graphic papers, the grade is registered under REACH 1907/2006. The terminal products are microporous inkjet photo papers, cast-coated packaging board, and paper label face stock where surface strength and low linting are specified.
On high-speed envelope lines running at 20,000–60,000 units/h, the remoistenable adhesive prepared from Poval 49-88 differs from dextrin-based formulations in viscosity stability after cyclic humidity exposure between 20% and 80% relative humidity. The adhesive is compounded as a 12–18 wt% aqueous solution of Poval 49-88, with 5–10 parts per hundred resin of a humectant such as glycerol and 0.05–0.1 wt% of a nonionic defoamer to prevent microfoam during roll application. The grade’s 44.0–50.0 mPa·s solution viscosity at 4% is increased at working solids to a Brookfield viscosity of 1,200–3,500 mPa·s at 25°C, which matches the gravure roll transfer window on envelope flap applicators. The adhesive is dried at 60–80°C for 10–20 s in a forced-air tunnel, leaving a dry film of 0.8–1.5 g/m² on the flap or label edge. Remoistening at the point of closure is performed with a wetting roller applying 4–8 g/m² of water; the open time before flap sealing is 5–15 s, and the fibre-tearing bond is achieved after 10–30 s under 0.1–0.3 MPa nip pressure. Preservation of the liquid adhesive is maintained within pH 4.5–6.5, and the preservative package is selected to avoid isothiazolinone sensitisation under the classification criteria of EC 1272/2008. Compliance follows FDA 21 CFR 175.105 for indirect food-contact adhesives. The terminal products are envelopes, stamp gums, litho-applied label gums, and tamper-evident coupon sheets where remoistenability and low curl are specified.
Dry-pressed porcelain tile granulate requires an organic binder that pyrolyses below the onset of vitrification but still raises green strength after spray drying and press loading. Poval 49-88 is introduced as a 10–15 wt% aqueous solution at 0.5–2.0 wt% on the dry ceramic body, added to the slip after blunging and before spray drying. The spray-drying tower is operated with an inlet temperature of 180–250°C and an outlet temperature of 90–110°C; the binder in the atomised droplets migrates toward the granule surface during moisture removal, producing a hard shell that improves flowability. The granulate is pressed at 30–40 MPa in hydraulic presses, where the green strength is controlled to exceed 1.0 MPa in three-point bending on un-fired test bars, because lower values increase edge-crack losses during handling. During firing, the grade’s ash residue is kept below 0.4%, and the organic fraction decomposes between 400°C and 550°C, before the densification window of the tile body. The use of Poval 49-88 with 87.0–89.0 mol% hydrolysis reduces dusting during press filling compared with starch-only systems, and the resulting tile body is assessed for water absorption according to ISO 10545-3. The terminal products are porcelain stoneware tiles, technical ceramic substrates, and cordierite honeycomb catalyst carriers where a low ash residue is a process specification.
Polyester/cotton warp yarns with a size add-on of 10–14% respond to Poval 49-88 differently than to starch ethers when weaving sheds operate above 80% relative humidity. The size mix contains 6–10 wt% Poval 49-88 on total size solids, with the balance composed of modified starch, wax, and an antistatic agent; the grade is pre-dissolved separately at 90–95°C and metered into the starch cooker to avoid thermal degradation and gelation. On the slasher, the size liquor is maintained at 60–70°C and applied through a double-squeeze mangle at 20–40 kN/m nip load, yielding a size add-on that is measured by the desizing loss method. The partially hydrolysed PVOH film is less brittle than fully hydrolysed grades, which reduces size shed in the reed and improves weaving efficiency on high-speed air-jet looms running at 700–900 picks/min. After weaving, the size is removed in the desizing range at 60–80°C with water and a mild oxidising agent, because the 87.0–89.0 mol% hydrolysis level dissolves more readily than fully hydrolysed PVA and does not require strong alkali. Compliance is tested against Oeko-Tex Standard 100 residual substance limits and the formulation avoids APEO surfactants under the ZDHC MRSL. The terminal products are polyester/cotton shirting fabrics, workwear, and home textile sheeting where controlled warp size adhesion and clean removal are specified.
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KURARAY POVAL 49-88 is a partially hydrolysed polyvinyl alcohol resin, CAS 9002-89-5, supplied as white to pale-yellow granulate. The grade designation encodes a nominal 4 % aqueous solution viscosity of 49 mPa·s at 20 °C and a nominal degree of hydrolysis of 88 mol% under the supplier’s JIS K6726-based analytical framework. The remaining 12 mol% acetate groups depress crystallinity, reduce hot-water resistance, and increase cold-water swellability compared with fully hydrolysed polyvinyl alcohol grades. Because the polymer carries both secondary hydroxyl groups and residual acetate groups, it exhibits hydrogen bonding, surface activity, and compatibility with plasticizers and inorganic particulates that differ from 98 mol% grade behaviour. Aqueous solutions of 49-88 form gels less readily on cooling than fully hydrolysed grades, but dried films redissolve more readily.
Lot-release data are normally determined by JIS K6726 rather than by ISO methods because Japanese PVOH supply chain specifications retain this frame for degree of hydrolysis, ash, volatile content, and aqueous viscosity. The 4 % solution viscosity is a rotational Brookfield-type value, not an intrinsic viscosity; it distinguishes 49-88 from low-viscosity grades such as 22-88 and from high-viscosity grades such as 60-98. No direct equivalence to ISO 1133-1:2022 melt flow rate exists because 49-88 is not melt-processed without extensive plasticization. Purchasing specifications should also include residual methanol and sodium acetate limits where the application is food-contact or low-ash electronic ceramic binder.
| Property | Specification range | Analytical reference |
|---|---|---|
| 4% aqueous solution viscosity at 20 °C | 44.0–54.0 mPa·s | JIS K6726 |
| Degree of hydrolysis | 86.5–89.0 mol% | JIS K6726 |
| Volatile matter | ≤5.0 % by mass | JIS K6726 |
| Ash | ≤0.5 % by mass | JIS K6726 |
| pH of 4% aqueous solution | 5.0–7.0 | JIS K6726 |
An unheated suspension below 40 °C hydrates rapidly and can form gel lumps if direct batch addition is attempted. The preferred makeup sequence is to add the granulate to a vortex of cold water under high-shear dispersion, then heat to 85–90 °C for 30–45 min with low-shear agitation until the solution clears. A 10 % aqueous solution at 20 °C is highly viscous; transfer lines should be sized for several thousand millipascal-seconds, and jacketed storage below 15 °C is applied to avoid skinning and microbial growth. Filtration through 100 µm or finer bag filters is applied before the solution enters coating or reactor feed systems. Because published rheological curves for this exact grade across all shear rates are limited, plant trials using a Brookfield LV or RVT spindle at 20 rpm are used to set pumping limits.
In vinyl acetate homopolymer and vinyl acetate-ethylene copolymer latex production, 49-88 is fed as a pre-dissolved 10–15 % aqueous solution. The grade functions as a protective colloid by adsorbing at the polymer-water interface and providing steric stabilization during particle nucleation and growth. The medium viscosity raises continuous-phase viscosity more than a 22-88 grade at equal colloid content, shifting the particle size distribution toward coarser particles and raising latex low-shear viscosity. Typical use levels are 2–6 wt% based on monomer, depending on particle size, scrub resistance, and freeze-thaw stability. In redox-initiated emulsions polymerized with sodium formaldehyde sulfoxylate and tert-butyl hydroperoxide at 55–65 °C, the grade remains stable against coagulation. The residual acetate groups provide higher surface activity than fully hydrolysed grades, reducing added surfactant demand in some emulsion systems but increasing foam generation in comparative latex trials. Defoamer demand is therefore higher than with 60-98 in equivalent formulations. Latex viscosity is not equivalent to grade viscosity; it is governed by particle size, swell ratio, and serum viscosity.
Surface size formulations based on oxidized starch and 49-88 are applied at 3–6 % solids on a film press or inclined size press. The PVOH component raises dry pick resistance, evaluated by IGT pick testing according to ISO 3783, and reduces dusting without producing the high water resistance of fully hydrolysed grades. Cobb60 water absorption measured according to ISO 535 increases relative to a 98 mol% grade; this is acceptable where repulpability and remoistenability are required. The medium viscosity assists film split control at high machine speed, but transfer roll shear stability should be checked above 1,200 m/min. Published data for this exact grade in size press formulations is limited; mill trials with size press solids and nip load are required.
In textile warp sizing of cotton and polyester-cotton blends, the grade is blended with starch or acrylic size at 6–12 % solids. Because the degree of hydrolysis is 88 mol%, the dried size film is sufficiently strong to reduce yarn hairiness but remains removable in hot-water desizing at 70–90 °C without enzyme treatment. A 4 % solution viscosity below 44 mPa·s indicates molecular weight reduction from thermal or oxidative damage during size cooking. High-shear jet cooking at 110–120 °C for 15–20 min destroys undispersed gel particles. Steam traps with surface temperatures above 160 °C should be avoided because dried PVOH on internal surfaces yellows and forms crosslinked deposits. The residual acetate content reduces minimum film-forming temperature and improves adhesion to hydrophobic polyester compared with fully hydrolysed PVOH, but lowers yarn tensile strength at high humidity when measured according to ASTM D2256.
In alumina and zirconia green tape casting, 49-88 is dissolved at 10–15 % in an aqueous slurry containing dispersant and plasticizer. The binder contributes green strength and controls crack propagation during drying. The partially hydrolysed grade generates less foam than fully hydrolysed grades but still requires a defoamer in the slurry. Ash content is critical; the ≤0.5 % ash specification is a maximum, and low-ash electronic ceramic grades require verification of sodium oxide and iron oxide below 100 ppm each before lot acceptance. Thermogravimetric analysis under air at 10 °C/min is used to establish burnout; for PVOH binders, burnout is typically completed at 450–500 °C, but the exact temperature must be confirmed for the cast tape thickness and furnace atmosphere. The grade is not directly interchangeable with acrylic latex binders because PVOH contributes higher green strength but also higher slurry viscosity and stronger sensitivity to calcium ions in hard water.
In vinyl chloride suspension polymerisation, 49-88 acts as a primary suspending agent. It is typically combined with a lower-viscosity PVOH such as 22-88 or a cellulose ether to tune PVC grain porosity and plasticizer uptake. The high-molecular-weight fraction of 49-88 increases the zero-shear viscosity of the aqueous phase and strengthens the monomer droplet skin, reducing coarse particle formation. Reactor charging sequences in a 10 m³ stirred stainless steel autoclave at 55–65 °C use 0.05–0.15 wt% PVOH based on monomer. Oxygen must be purged below 10 ppm in the headspace. Because 49-88 has a degree of hydrolysis of 88 mol%, it is less effective at reducing vinyl chloride droplet coalescence than a fully hydrolysed grade at equivalent viscosity, but it contributes to a more open PVC grain structure and lower gel count. The exact plasticizer uptake of the final PVC grain is reactor-specific; published data for this exact grade in a given autoclave configuration is limited.
Cast films from 49-88 dissolve more readily in cold water than films from fully hydrolysed grades. Film tensile strength according to ISO 527-3 is typically lower than that of 60-98 because the residual acetate groups reduce crystallinity, while elongation at break is higher under standard conditioning at 23 °C and 50 % RH. Water resistance is not zero: a dried film remains intact in cold water for a period that depends on thickness, plasticizer content, and water temperature, then softens and disintegrates. For unit-dose detergent film applications, 49-88 is not normally used alone; it may be blended with a more fully hydrolysed grade or with a dedicated cold-water soluble grade to balance dissolution speed and mechanical strength. Films are typically cast from a 15–20 % aqueous solution onto a heated chrome roll or steel belt at 80–95 °C. Surface temperatures above 110 °C cause skinning and microcracking. The medium viscosity increases die-lip thickness control in slot-die coating but reduces maximum line speed relative to lower-viscosity grades. No published ISO 527-3 data for this specific unfilled PVOH film grade are available; the above comparison is directional and must be confirmed on the target film line.
The adjacent grades differ mainly in aqueous viscosity and degree of hydrolysis. The viscosity term controls process film strength, solution handling, and continuous-phase viscosity in polymerisation; the hydrolysis term controls water resistance, crystallinity, and surface activity. Table 2 summarises the directional differences used for grade selection; the certificate of analysis for each lot is controlling.
| Grade | Nominal 4% viscosity at 20 °C (mPa·s) | Degree of hydrolysis (mol%) | Relative process behaviour |
|---|---|---|---|
| 22-88 | 22.0–27.0 | 86.5–89.0 | Lower serum viscosity and film tensile; finer particle size often obtained in emulsion polymerisation. |
| 49-88 | 44.0–54.0 | 86.5–89.0 | Intermediate protective colloid strength and film tensile; higher solution viscosity for sizing and ceramic green tape. |
| 48-80 | 44.0–54.0 | 78.0–82.0 | Higher residual acetate; lower crystallinity and water resistance; more surface-active and more hydrophobic character. |
| 60-98 | 58.0–68.0 | 98.0–99.0 | Requires hot-water dissolution; higher tensile, lower surface activity, and stronger water resistance after drying. |
For indirect food-contact adhesive and size formulations, compliance should be assessed under FDA 21 CFR 175.105 for adhesive components or FDA 21 CFR 176.170 for paper and paperboard components, not by grade composition alone. Under EU Regulation 10/2011, polyvinyl alcohol is listed for use in plastic food-contact materials, but the finished article must meet overall migration and specific migration limits. 49-88 should be stored in sealed, moisture-tight packaging at 10–30 °C and relative humidity below 60 %. At higher humidity, the granulate absorbs moisture, which alters apparent viscosity and can cause bridging in loss-in-weight feeders. If exposed to relative humidity above 60 % for prolonged periods, pre-drying in a vacuum dryer at 50–60 °C for 2–3 h is applied before use in melt or dry-blend processes. Dust from the granulate can form an explosive organic dust cloud; conveying systems should be grounded and operated with a dust concentration below the lower explosive limit. Avoid mixing the dry powder with strong oxidizers, including concentrated nitric acid, or with transition-metal salts that catalyze oxidative degradation.
