| HS Code | 261917 |
| Product Type | Partially saponified polyvinyl alcohol (PVA) |
| Cas Number | 9002-89-5 |
| Appearance | White to pale yellow granular powder |
| Degree Of Saponification | 78.5–81.5 mol% |
| Viscosity 4 Aqueous Solution 20 C | 20.0–24.0 mPa·s |
| Ph 4 Aqueous Solution | 5.0–7.0 |
| Volatile Content | ≤5.0 wt% |
| Ash Content | ≤0.5 wt% |
| Average Degree Of Polymerization | ~1800 |
| Water Solubility | Soluble in hot water; requires heating for dissolution |
| Specific Gravity | ~1.27 |
| Bulk Density | 0.3–0.5 g/cm³ |
As an accredited GOHSENOL KH-20 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | GOHSENOL KH-20 polyvinyl alcohol is supplied as a free-flowing white powder in 20 kg multi-layer paper bags with polyethylene liner. |
| Container Loading (20′ FCL) | GOHSENOL KH-20 shipped in 20′ FCL, packed in palletized bags, secured to prevent shifting, with moisture protection. |
| Shipping | GOHSENOL KH-20 (polyvinyl alcohol) ships as dry, free-flowing powder in sealed multi-layer paper bags or drums to protect from moisture. Non-hazardous under transport regulations; however, avoid dust generation and store in cool, dry, ventilated areas. Keep away from ignition sources and incompatible materials. Handle with standard hygiene practices to prevent inhalation. |
| Storage | Store GOHSENOL KH-20 in its original, tightly sealed container in a cool, dry, well-ventilated area. Keep away from moisture, direct sunlight, heat, and ignition sources. Avoid generating dust and prevent contact with incompatible materials. Ensure the container remains closed when not in use to maintain product integrity and shelf life. |
| Shelf Life | Shelf life is typically 24 months when stored unopened in a cool, dry place, away from moisture and direct sunlight. |
In aqueous emulsion polymerisation of vinyl acetate and vinyl acetate-ethylene, GOHSENOL KH-20 functions as a protective colloid whose performance is governed by the ratio of aqueous-phase viscosity to monomer droplet shear stability. Typical addition levels fall between 2.0 and 6.0 parts per 100 parts monomer; at 4.0 parts per 100 parts vinyl acetate, a 10–12 % aqueous stock solution prepared at 90–95 °C is charged to a glass-lined 5–20 m³ reactor equipped with a pitched-blade turbine at 3–5 m/s tip speed and baffle/coil cooling. Delayed monomer addition over 3–4 h with ammonium persulphate or hydrogen peroxide/tartaric acid initiator maintains the polymerisation exotherm within 75–85 °C. Coagulum concentration is measured by filtration through a 100 mesh sieve and reported as weight percent of latex solids; production records show that deviations in KH-20 hydration temperature below 85 °C increase filter residue because partially swollen particles act as seed sites for coagulum. Compliance for adhesive and paper-laminating emulsions is established under 21 CFR 175.105 for food-packaging adhesives, with latex solids and residual monomer controlled by ISO 3251:2019 and internal headspace gas chromatography limits below 0.1 %. Acidic buffer control is required when PVA-protected lattices are combined with amine-based neutralisers above pH 6.5, because rapid viscosity collapse and localised destabilisation can occur. Terminal products include PVAc woodworking adhesives, VAE redispersible polymer powders for dry-mix mortars, carpet backing compounds, and paper-to-paper laminating adhesives.
In pigmented paper coating, the binding contribution of GOHSENOL KH-20 is evaluated through IGT pick velocity and wet pick resistance, not solely through binder addition level. For blade-coated white-top liner and label stock, KH-20 is added at 0.5–3.0 parts dry polymer per 100 parts total pigment, normally in combination with a carboxylated styrene-butadiene latex at 4–8 parts and a starch or carboxymethyl cellulose cobinder at 0.5–1.5 parts. The PVA is hydrated separately in a jet cooker at 105–110 °C for 20–30 min, then cooled to 50–60 °C before being mixed with kaolin and ground calcium carbonate at 65–72 % total solids using a rotor-stator high-shear disperser. Coating application is performed on a blade coater at 800–1500 m/min, followed by air flotation and infrared drying; typical dry coat weights are 6–12 g/m². Production troubleshooting data associate blade scratches and film split at the blade heel with PVA solutions that have not passed through a 100 μm screen, while viscosity drift of the coating colour is observed when PVA solution is added above 70 °C due to thermal shock with SB latex. Regulatory compliance for food-contact paper and board is anchored to 21 CFR 176.170 for aqueous and fatty foods and 21 CFR 176.180 for dry foods, with European materials compliance assessed under Regulation (EC) No 1935/2004 and German BfR recommendations where applicable. Terminal products include coated folding carton board, release liner, label facestock, and inkjet receiver sheets.In slasher sizing of spun polyester/cotton warp yarns, GOHSENOL KH-20 is formulated at 8–15 % total size solids, with PVA occupying 10–25 parts per 100 parts of modified starch or starch ether. High-pressure cooking at 110–130 °C for 20–30 min is required to eliminate microgel residues that would otherwise deposit at the size-box nip. The size liquor is applied at 70–85 °C through a double-dip, double-squeeze configuration, with squeeze pressure set to 2–4 bar; drying cylinder surface temperatures are graded from 105 °C to 135 °C to prevent skin-over and size film brittleness. Desizing in downstream finishing is performed with hot alkaline hydrogen peroxide wash for the PVA component and enzymatic treatment for the starch component, and incomplete PVA removal is a known cause of stiff fabric handle and dye uptake variation. Compliance under REACH requires site-specific demonstration of wastewater COD reduction after size recovery or anaerobic treatment; finished articles are assessed for restricted substance residues under OEKO-TEX Standard 100 and ZDHC MRSL v3.1. Terminal outputs are woven shirting, workwear, bed sheeting, and lining fabrics.
The dry-mix route for GOHSENOL KH-20 in C1 and C2 cementitious tile adhesives is viable only if the polymer is dry-blended with the mineral fraction before water is introduced; direct addition to an alkaline wet mix at pH above 12 produces lumping. Addition levels fall between 0.2 and 1.0 wt% of total dry mix in tile adhesives, and 0.3–1.2 wt% in wall putty or skim coat formulations. A forced-action mortar mixer or twin-shaft batch mixer is used to disperse the powder at 60–120 rpm for 6–10 min; after mixing with water according to EN 12004-2:2017 or manufacturer water demand, the slurry is applied by notched trowel at 20–25 °C and 50–70 % RH. Tensile adhesion testing under EN 12004-2:2017 differentiates C1 from C2 products; in PVA-modified C1 mixes, typical values must exceed 0.5 N/mm² after standard, water immersion, and heat ageing conditions. Excessive PVA addition above 1.2 wt% depresses adhesion after water immersion because the polyvinyl alcohol reversibly plasticises at the cement-polymer interface. Regulatory demonstration is tied to EN 12004:2017 and ISO 13007-2:2013, with volatile organic compound limits under AgBB or French A+ where required. Terminal products include bagged C1/C2 tile adhesives, wall putty, and cement-based repair mortars.
GOHSENOL KH-20 is processed into water-soluble film by casting a deaerated aqueous solution at 10–25 % solids onto a polished chill roll; the solution is prepared at 90–95 °C and held under vacuum at 200–400 mbar to remove bubbles before slot-die application. Plasticiser loading with glycerol or sorbitol is 10–20 parts per 100 parts PVA, with 0.1–0.5 parts release agent and 0.1–0.3 parts anti-block. Drying uses multi-zone hot air from 70 °C to 110 °C and conditioning to 20–25 % RH; moisture content of the film must be maintained between 3 % and 8 % to avoid brittleness and blocking. Seal initiation temperature on form-fill-seal equipment is measured by ASTM F88/F88M-21 on 50 μm film and typically falls below 200 °C when plasticiser content is above 15 parts; below 10 parts plasticiser, seal strength declines sharply and film splitting at the seal shoulder is observed. Mechanical property evaluation follows ISO 527-3:2018 and ASTM D882-12, while ready biodegradability is demonstrated by OECD 301B. Compliance for detergent unit-dose packaging under EU Regulation (EC) No 648/2004 and food-contact limitations under relevant national provisions requires verification of residual solvent and plasticiser migration; published data for this specific grade in unit-dose film architectures remains limited, so seal strength and dissolution time must be revalidated on production-scale film lines. Terminal products include laundry detergent unit-dose pods, agrochemical water-soluble sachets, embroidery backing film, and transfer printing release sheets.
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GOHSENOL KH-20 is a partially hydrolysed polyvinyl alcohol supplied by Nippon Gohsei as a white to off-white granular powder. The model designation places the 4% aqueous solution viscosity at 20°C in the range of 20.0–24.0 mPa·s when tested according to JIS K6726. The degree of hydrolysis is specified as 78.5–81.5 mol%, corresponding to a residual acetyl content of 18.5–21.5 mol%. Volatile matter is controlled at ≤5.0% by mass, and ash content is controlled at ≤0.5% by mass. The pH of a 4% aqueous solution is specified in the range of 5.0–7.0. These values define a cold-water-soluble polymer grade used in emulsion polymerisation as a protective colloid, in paper sizing and adhesive systems, in textile warp sizing, and in water-soluble binder applications where low crystallinity and moderate solution viscosity are required. The residual acetyl groups disrupt intermolecular hydrogen bonding and lower crystallinity relative to fully hydrolysed grades, allowing hydration at lower temperatures and reducing the energy input required for solution preparation in downstream processing.
| Parameter | Unit | Specification | Test method |
|---|---|---|---|
| Viscosity of 4% aqueous solution at 20°C | mPa·s | 20.0–24.0 | JIS K6726 |
| Degree of hydrolysis | mol% | 78.5–81.5 | JIS K6726 |
| Residual acetyl content | mol% | 18.5–21.5 | Calculated from degree of hydrolysis |
| Volatile matter | % by mass | ≤5.0 | JIS K6726 |
| Ash content as Na₂O | % by mass | ≤0.5 | JIS K6726 |
| pH of 4% aqueous solution | — | 5.0–7.0 | JIS K6726 |
The primary chemical distinction is the residual acetyl content. In GOHSENOL KH-20, the degree of hydrolysis of 78.5–81.5 mol% means that 18.5–21.5 mol% of the original vinyl acetate units remain unhydrolysed. These pendant acetate groups disrupt the regular sequence of secondary hydroxyl groups, reducing crystallinity and increasing water swellability. Fully hydrolysed polyvinyl alcohol grades with hydrolysis above 98 mol% possess longer hydroxyl sequences and form stronger intermolecular hydrogen bonds, producing crystalline domains that require hot water and extended holding time for complete dissolution. In low-temperature sizing operations, KH-20 can be dispersed in cold water at 20–30°C and then heated to 70–80°C for 30–60 min using a cowles disperser. Fully hydrolysed grades generally require temperatures of 90–95°C for comparable dissolution under practical mixing conditions.
The lower crystallinity of KH-20 also affects dried film properties. Films cast from a 78.5–81.5 mol% hydrolysed grade tend to exhibit lower tensile modulus and greater elongation than films from fully hydrolysed grades, but they also display higher water sensitivity. This makes the grade suitable for applications requiring flexibility and cold-water removability rather than boiling-water resistance. The solution viscosity specification of 20.0–24.0 mPa·s at 4% solids is a reference value measured after complete dissolution and conditioning at 20°C; it is not a direct coating viscosity at processing temperature. Processors comparing KH-20 against fully hydrolysed grades should therefore evaluate both dissolution temperature and final film water resistance, because the degree of hydrolysis is the dominant determinant of those properties.
In low-temperature maintenance of aqueous solutions, partially hydrolysed PVA can undergo viscosity drift if the solution is held for extended periods above 70°C due to evaporation and re-association of polymer chains. Closed or jacketed mixing vessels with temperature control are therefore preferred. The product is not a direct drop-in replacement for fully hydrolysed PVA in applications where boiling-water resistance, high oxygen barrier, or high dry tensile strength is required. When those properties are required, a fully hydrolysed grade should be specified. Conversely, when cold-water solubility, interfacial activity, and lower processing temperature are the primary constraints, KH-20 is selected.
In emulsion polymerisation, GOHSENOL KH-20 functions as a protective colloid in vinyl acetate, acrylic, and related monomer systems. A 10 wt% aqueous solution is typically prepared by dispersing the powder in the aqueous phase at 20–40°C and then heating to 75–85°C before cooling to reactor temperature. The solution is charged at 0.5–3.0 parts per hundred monomer, depending on desired latex particle size and stabilisation requirement. The partially hydrolysed grade adsorbs at the monomer–water interface and provides steric stabilisation to growing latex particles. The viscosity specification of 20.0–24.0 mPa·s at 4% solids gives a predictable solution viscosity in the reactor, but the final latex viscosity also depends on particle size distribution, total solids, residual monomer, and pH. When charged into a jacketed glass-lined reactor with a pitched-blade turbine operating at 100–180 rpm, the grade disperses without lumping when added slowly to the aqueous phase before heating.
The residual acetyl content of 18.5–21.5 mol% is important for emulsion stabilisation because fully hydrolysed grades tend to produce larger particles and lower latex stability at equivalent addition levels. The operational limit is that excessive KH-20 addition above 5 parts per hundred monomer can produce high-viscosity latex that complicates heat transfer, increases reactor wall fouling, and may require post-polymerisation dilution. The use of KH-20 in emulsion polymerisation is therefore bounded by the required latex solids and viscosity ceiling of the reactor system. Published data for this specific configuration is limited in the open literature, so plant-scale trials with a defined monomer formulation are necessary to establish the optimum protective colloid concentration.
In size-press treatment of paper and board, GOHSENOL KH-20 is combined with oxidised starch or enzyme-converted starch. The degree of hydrolysis of 78.5–81.5 mol% promotes cold-water solubility and reduces chain–chain association, allowing the size press to operate at 40–60°C without excessive viscosity increase. A typical size-press working solids range is 4–8 wt%, with the PVA fraction at 10–30% of total dry solids. The KH-20 viscosity at 4% solids provides sufficient film strength when combined with starch, but the final blend viscosity must be checked with a Brookfield viscometer at 60°C to avoid rod bleeding and size penetration variation. In corrugating adhesives, the grade is added to starch formulations at 0.5–2.0 parts per hundred dry starch to improve wet tack and bonding speed. The partially hydrolysed polymer stabilises the starch gel under temperature cycling and reduces viscosity sensitivity at elevated machine speeds.
The difference between KH-20 and the lower-viscosity grade KH-17 is operationally significant in this application. Table 2 compares typical specification ranges. KH-17 has a 4% solution viscosity range of 16.0–19.0 mPa·s, which permits higher solids at equal target viscosity but provides lower cohesive strength at equal dry-basis addition. KH-20, with 20.0–24.0 mPa·s, requires slightly more dilution for the same target viscosity but contributes higher molecular weight and greater film strength. Because both grades share the same degree of hydrolysis, differences in solubility and water sensitivity are not large; the practical difference is viscosity and resulting mechanical film properties. The selection is therefore controlled by the viscosity ceiling of the applicator and the desired dry-basis addition.
| Parameter | GOHSENOL KH-17 | GOHSENOL KH-20 | Test method |
|---|---|---|---|
| Viscosity of 4% aqueous solution at 20°C | 16.0–19.0 mPa·s | 20.0–24.0 mPa·s | JIS K6726 |
| Degree of hydrolysis | 78.5–81.5 mol% | 78.5–81.5 mol% | JIS K6726 |
| Volatile matter | ≤5.0% | ≤5.0% | JIS K6726 |
| Ash content as Na₂O | ≤0.5% | ≤0.5% | JIS K6726 |
| pH of 4% aqueous solution | 5.0–7.0 | 5.0–7.0 | JIS K6726 |
On a slasher for spun yarns, KH-20 is included in warp size mixtures at 10–40% of dry size solids. The lower crystalline order produces a flexible film that adheres to cotton and polyester–cotton blends; the size film is removed later at 60–80°C in a desizing wash. Yarn tensile retention after sizing can be evaluated with ASTM D2256-15. The film’s abrasion resistance depends on add-on and size penetration. A size box operating at a warp speed of 100 m/min may require a size viscosity between 15 and 40 mPa·s at 60°C, which is achieved by adjusting solids and starch ratio. KH-20 is selected over KH-17 when the mill needs higher cohesion at lower wet pick-up. The higher solution viscosity of KH-20 contributes to size film integrity at low add-on, but the concentration must be limited to prevent excessive size-box viscosity and yarn shedding. The product is also used in nonwoven binder formulations where cold-water solubility and low crystallinity provide uniform binder deposition and easier wash-off from equipment.
The 4% specification viscosity is a reference point, not a coating viscosity. In slot-die coating or knife-over-roll coating of water-soluble films, a formulation at 10 wt% KH-20 at 20°C can exceed 500 mPa·s at low shear, depending on temperature history and shear rate. This imposes a processing ceiling. When the target wet film thickness is 20–50 μm, the coating fluid should be held at 30–50°C to maintain a Brookfield viscosity below 200 mPa·s. If the slot-die lip gap is below 300 μm, high viscosity causes ribbing and die-lip deposits. Reducing the solution solids to 6–8 wt% brings the viscosity into a pumpable range but also reduces drying efficiency. In these cases, a lower-viscosity partially hydrolysed grade such as KH-17 may be selected, or the coating system may be heated.
The difference between KH-20 and KH-17 is primarily viscosity under matched solids. A user evaluating both grades should prepare a viscosity curve from 2% to 10% solids at 20°C and 60°C before specifying the grade. For high-solids adhesive compounding, a heated transfer line maintained at 55–65°C prevents viscosity drift during extended runs. The viscosity of partially hydrolysed PVA solutions is temperature dependent, and cooling below 15°C can produce pronounced thickening, especially at solids above 10%. This is a critical threshold for plants running unheated piping in cold climates. The product should therefore be stored and processed in a closed system with temperature control to avoid gelation and transfer pump overload.
Storage of GOHSENOL KH-20 requires dry indoor conditions because the powder absorbs atmospheric moisture. The volatile matter specification of ≤5.0% is based on as-shipped material, and open storage at relative humidity above 60% can raise moisture content and reduce flowability. The powder should be kept in sealed bags on pallets in a ventilated area at 5–30°C. Dust extraction should be used when transferring bulk quantities. For paper and paperboard food-contact applications, compliance is typically evaluated under FDA 21 CFR 176.170 and FDA 21 CFR 176.180; the final package must meet migration testing for the specific food type and use condition. The grade is not intended as a direct food additive.
