| HS Code | 295085 |
| Product Name | GOHSENOL NH-18 |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White to pale yellow powder |
| Degree Of Hydrolysis | 88.0 ± 2.0 mol% (partially hydrolyzed) |
| Viscosity 4 Percent Aqueous Solution 20c | 40.0 - 52.0 mPa·s |
| Ph 4 Percent Aqueous Solution | 5.0 - 7.0 |
| Average Degree Of Polymerization | 1800 |
| Molecular Weight | Approximately 80,000 - 85,000 |
| Volatile Content | ≤ 5.0% |
| Ash Content | ≤ 1.0% |
| Solubility | Soluble in hot water; practically insoluble in most organic solvents |
As an accredited GOHSENOL NH-18 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | GOHSENOL NH-18 polyvinyl alcohol is packaged in 20 kg multi-wall paper bags with an inner polyethylene liner for moisture protection. |
| Container Loading (20′ FCL) | 20′ FCL for GOHSENOL NH-18: 25kg paper bags palletized, shrink-wrapped, loaded with even weight distribution and secured to prevent shifting. |
| Shipping | GOHSENOL NH-18, a polyvinyl alcohol resin, is not classified as dangerous goods under international transport regulations. Ship as “Polyvinyl Alcohol” in sealed, dry containers to prevent moisture absorption. Avoid creating dust clouds; if spilled, sweep up carefully. No special hazard labeling required for road, sea, rail, or air freight. |
| Storage | Store GOHSENOL NH-18 in its original, tightly sealed container in a cool, dry, well-ventilated area. Protect from moisture, humidity, and direct sunlight. Keep away from heat, open flames, and incompatible substances. Avoid generating dust; keep container closed when not in use. Follow manufacturer’s shelf-life recommendations. |
| Shelf Life | Shelf life is typically 2 years from manufacture when stored sealed, dry, and cool. |
In high-speed alkaline fine paper production, GOHSENOL NH-18 functions as a fully hydrolysed polyvinyl alcohol surface-sizing agent whose 98.0–99.0 mol% hydrolysis level and 25.0–30.0 mPa·s 4 wt% aqueous viscosity at 20°C are controlled under JIS K6726. The grade is specified at a degree of polymerisation near 1,800, which places it between low-viscosity grades used for fine surface films and heavy-body grades reserved for high-strength laminating. The stock solution is prepared by first slurrying the powder in 15–25°C demineralised water at 6–10 wt%, then raising the batch temperature to 90–95°C under 250–400 rpm agitation for 30–45 minutes until gel particles disappear. At the size press, the cooked polyvinyl alcohol solution is blended with oxidised corn starch at a PVA/starch solids ratio between 5:100 and 15:100. Machine-side size solids are maintained at 8–14% depending on base sheet ash content and internal sizing demand. A rod-metered film size press operating at 600–1200 m/min deposits 2–5 g/m² wet size film. The high hydrolysis level reduces moisture sensitivity of the dried size film compared with 88 mol% grades, and surface strength is measured by ISO 3783 IGT pick testing with acceptance thresholds set per paper grade. Terminal products include offset printing papers, envelope stock, inkjet base papers, and linerboard requiring controlled lint and dusting behaviour. For food-contact paper and paperboard produced in the United States, the finished size film falls under FDA 21 CFR 176.170 when use conditions are consistent with the food type and temperature limitations stated in the regulation.
Warp sizing for high-density plain-weave and twill fabrics requires a size film that resists humidity-driven breakage on air-jet looms. GOHSENOL NH-18 is cooked at 8–12 wt% solids in a jet cooker or atmospheric kettle at 85–95°C and then held in a size box at 80–85°C. A blend of NH-18 with thin-boiling starch at 1:4 to 1:1 PVA-to-starch dry solids is used because the starch reduces total size cost while the polyvinyl alcohol supplies film toughness. For combed cotton and polyester/cotton spun yarns in the Ne 30–60 range, size add-on is controlled between 9% and 14% by dry fibre weight. Squeeze roller pressure is set at 2.0–4.0 kN/m and slasher speed is restricted to 40–80 m/min to prevent excessive size penetration into the yarn core. The fully hydrolysed structure produces a more crystalline size film after drying on the loom beam, resulting in lower elongation at break and higher tensile modulus than partially hydrolysed grades. Weaving performance is assessed indirectly through loom stop rate per 100,000 weft insertions rather than by a single material property; mill-specific correlations are required because cloth construction and loom type dominate the result. Desizing of NH-18-containing size films is conducted in continuous desize ranges at 80–90°C with 0.3–0.8 wt% hydrogen peroxide or an oxidative desizing agent, followed by hot washing at 85°C. Ultrafiltration may recover polyvinyl alcohol from wash water in closed-loop systems, with reported recovery rates above 80% under controlled pH. Terminal fabrics include poplin, twill, workwear, bed sheeting, and high-density downproof constructions. Wastewater compliance is site-specific, but recovered PVA reduces chemical oxygen demand load in mill effluent.
Pressurised vinyl acetate–ethylene emulsion polymerisation in a 10–50 m³ stirred reactor at 60–80°C and 0.5–4.0 MPa can be stabilised with a protective colloid package that includes GOHSENOL NH-18 at 20–40% of the total polyvinyl alcohol charge. The total colloid addition is typically 3–7 wt% based on monomers. The fully hydrolysed NH-18 component contributes high solution viscosity and limited cold-water solubility, which increases early-stage emulsion viscosity and moderates particle nucleation. Radical chain transfer to the polyvinyl alcohol backbone leads to grafting and formation of a colloid-rich surface layer; graft density depends on initiator concentration, temperature, and ethylene pressure. Reactor pH is maintained at 4.0–5.5 with buffered sodium acetate or sodium bicarbonate, and redox initiation controls polymerisation rate. Final dispersions are normally 55–65 wt% solids with Brookfield viscosities of 2000–8000 mPa·s. A process limitation exists: if the NH-18 fraction exceeds approximately 40% of the colloid charge, reactor viscosity may rise above 12,000 mPa·s during polymerisation, reducing heat transfer and increasing coagulum formation. The balance of the colloid is therefore usually a 88 mol% hydrolysis grade or a cellulose ether. Polymer films are tested for adhesion by ISO 527-3 or EN 204 where wood-adhesive classification is required. Terminal products include wood assembly adhesives, laminating adhesives, nonwoven binders, and paper-to-film laminates. In the United States, adhesives used in food packaging may be subject to FDA 21 CFR 175.105; in Europe the binder formulation is assessed under Regulation (EC) No 1907/2006 for registered substances.
In suspension polymerisation of vinyl chloride monomer, GOHSENOL NH-18 is evaluated as a secondary dispersant rather than the sole interfacial agent. The 98.0–99.0 mol% hydrolysis level generates a lower stabilising effect than 70–80 mol% grades at equivalent concentration, but it can modify final resin particle density and plasticiser absorption when combined with a primary low-DP polyvinyl alcohol or hydroxypropyl methylcellulose. A typical starting-point addition is 0.03–0.08 parts per 100 parts vinyl chloride monomer in a 30–80 m³ stirred autoclave at 55–65°C, with turbine impeller speed between 180 rpm and 260 rpm. The suspension is maintained at reactor pressure until monomer conversion reaches 85–90%; reactor pressure drop is used to terminate polymerisation. Final PVC particle size distribution is measured by laser diffraction, and molecular weight is determined as K-value by ISO 1628-2. Plasticiser absorption and bulk density are sensitive to the ratio of primary to secondary dispersant and cannot be predicted from the polyvinyl alcohol grade alone. Published data for NH-18 in this specific VCM configuration is limited, and reactor-scale optimisation is required. Terminal products include pipe-grade PVC, window profile compound, and calendered sheet compound, where a narrow particle size distribution and consistent plasticiser uptake are required.
GOHSENOL NH-18 can be cast into an optical-grade polyvinyl alcohol film from an 8–12 wt% aqueous solution on a chrome-plated steel belt or drum dryer at 60–90°C. The high hydrolysis level increases resistance to dissolution in the subsequent wet-stretching bath and provides high iodine complexation capacity after orientation. In a typical polariser line, the cast film is uniaxially stretched 3:1 to 5:1 in boric acid solution at 40–60°C, then immersed in an iodine–potassium iodide solution with boric acid crosslinking. Residual water before dry-stretching is maintained at 20–30 wt% to prevent film brittleness; drying beyond this range raises the glass transition temperature above the stretching temperature and induces microcracks. Tensile properties of conditioned film are measured by ISO 527-3. Optical transmittance and polarisation efficiency are assessed on stretched film by polarimetric methods specific to the production line. The exact draw ratio, bath composition, and drying profile must be matched to the viscosity grade; published data for NH-18 in this specific optical-film configuration is limited. Terminal products include polyvinyl alcohol optical film for LCD polarisers, iodine-type polarising film, and film intermediates used before final lamination. The 25.0–30.0 mPa·s viscosity of NH-18 provides a balance between cast film strength and solution handling, but the stretching window is narrower than for higher-DP grades.
In dry-mix construction mortars, GOHSENOL NH-18 is used as a spray-drying protective colloid for aqueous ethylene-vinyl acetate copolymer dispersions that are converted into redispersible polymer powders. The feed dispersion at 45–55 wt% solids is atomised through a rotary atomiser in a co-current spray dryer with inlet air at 110–150°C and outlet air at 55–70°C. The polyvinyl alcohol colloid content is normally 3–10 wt% based on polymer solids; the fully hydrolysed grade contributes mechanical strength to the final mortar film but raises the minimum film-forming temperature relative to 88 mol% hydrolysis colloids. The resulting powder is dry-blended into tile adhesives, thin-bed mortars, and self-levelling compounds. A formulation containing 1.5–3.5 wt% redispersible polymer powder in a C2 cementitious tile adhesive is tested for tensile adhesion after water immersion and heat ageing under EN 12004. A processing boundary exists in spray drying: if the outlet temperature exceeds 70°C, the high-hydrolysis PVA shell may become less redispersible, giving coarse residue after mixing with water. A 63 µm sieve residue test is used to monitor redispersibility. Terminal products include C1/C2 tile adhesives, external thermal insulation composite systems, and cementitious patching compounds.
For pre-coats and top-coats on coated freesheet, GOHSENOL NH-18 serves as a co-binder in pigmented paper coatings. The polymer is cooked at 10–15 wt% solids and then added to a coating colour containing 100 parts ground calcium carbonate or kaolin, 4–8 parts styrene-butadiene latex, 3–6 parts NH-18 solution solids, and 0.3–1.0 parts polyacrylate dispersant. The coating colour is adjusted to 58–65 wt% total solids and 1000–2500 mPa·s Brookfield viscosity at 100 rpm; high-shear capillary viscosity measured at 10,000 s⁻¹ is maintained at 50–120 mPa·s to prevent blade streaking. Blade coaters run at 800–1500 m/min with blade pressure between 0.8 kN/m and 1.5 kN/m. The NH-18 component improves water retention and contributes to surface strength after calendering. IGT surface strength by ISO 3783 and dry pick resistance are used as grade acceptance tests, with acceptance values set by individual paper machine and end-use specification. The terminal products include art paper, magazine paper, label stock, and folding boxboard. The use of polyvinyl alcohol in paper coatings is governed by the same food-contact requirements as surface sizing when the final board is intended for food packaging, including FDA 21 CFR 176.170 in the U.S. market.
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GOHSENOL NH-18 is a fully hydrolysed polyvinyl alcohol (PVOH) resin supplied as white to pale-yellow granules. The manufacturer’s technical data sheet defines the grade by a saponification degree of 98.0–99.0 mol% and a dynamic viscosity of 25.0–30.0 mPa·s for a 4% aqueous solution at 20°C, measured under JIS K6726. Volatile matter is controlled to ≤5.0%, ash as Na₂O to ≤0.4%, and pH of a 4% solution to 5.0–7.5. The “18” suffix identifies the viscosity bracket, not a concentration. NH-18 belongs to the fully hydrolysed NH series, distinguishing it from partially hydrolysed GOHSENOL GH and KH grades in cold-water solubility, dried-film water resistance, and tensile strength development. In aqueous make-down, the granulate is typically pre-slurried in cold water below 20°C before heating to 85–95°C to prevent fisheye formation.
Lot-to-lot control for NH-18 is anchored to JIS K6726 for saponification degree, viscosity, ash, and volatile content. The following table lists typical published ranges for selected GOHSENOL grades and should be verified against the certificate of analysis for each production batch. Variation within the 25.0–30.0 mPa·s bracket alters solution rheology during transfer; positive-displacement gear pumps with speed control are preferred over centrifugal pumps once viscosity exceeds 25 mPa·s.
| Grade | Degree of hydrolysis (mol%) | 4% aqueous viscosity at 20°C (mPa·s) | Test method |
|---|---|---|---|
| NH-18 | 98.0–99.0 | 25.0–30.0 | JIS K6726 |
| NH-20 | 98.0–99.0 | 35.0–45.0 | JIS K6726 |
| GH-17 | 86.5–89.0 | 27.0–33.0 | JIS K6726 |
| KH-17 | 78.5–82.0 | 27.0–33.0 | JIS K6726 |
Dissolution at production scale is typically performed in stainless steel jacketed vessels equipped with a slow anchor agitator at 10–20 rpm and a high-shear Cowles blade at 500–1,000 rpm. Complete hydration at 4–8% solids requires maintaining 85–95°C for 30–45 min. Viscosity rises sharply as the solution cools toward 60–70°C, and an open-tank surface can skin over when temperature drops below 75°C. The effective processing band is therefore constrained between hydration and thermal degradation; jacket control to ±2°C is used in production to avoid both undispersed gel bodies and heat-induced chain scission. Raising solution solids from 4% to 8% typically increases apparent viscosity by a factor of 2.5–3.5, which must be compensated through inline process viscometers on doctor-blade coaters or slot-die feed systems.
In paper and paperboard adhesive formulations, NH-18 is incorporated at 2–6 wt% dry basis to increase water resistance and dry tensile strength of starch or dextrin-based adhesive systems. The high degree of hydrolysis reduces swelling of the dried PVOH phase after 24 h water immersion. Bond performance is commonly evaluated according to ISO 1924-2:2008 for tensile energy absorption and TAPPI T 821 for pin adhesion in corrugated board. Production-scale mixing records show that NH-18 addition to starch adhesives in 500 L scraped-surface jacketed mixers raises clean-up demands after film drying; washdown requires hot water above 80°C and alkaline detergent. Compared with partially hydrolysed GH-17, NH-18 produces a dried film with lower equilibrium moisture pickup and lower cold-water solubility, but the granulate is not suitable for direct ambient-water dissolution without heat input.
The difference is primarily governed by residual acetate content. At 98.0–99.0 mol% hydrolysis, NH-18 contains only 1.0–2.0 mol% residual acetate groups, whereas GH-17 and KH-17 contain 11.0–13.5 mol% and 18.0–21.5 mol% residual acetate, respectively. The lower acetate content increases chain regularity, which raises crystallite density and reduces cold-water solubility. Consequently, NH-18 films exhibit higher tensile strength and lower elongation at break than partially hydrolysed grades at equal thickness when conditioned at 23°C and 50% RH and tested under ASTM D882-18. The same structural regularity raises the temperature required for full dissolution: NH-18 does not wet out adequately in water below 40°C, while KH-17 will hydrate at 20–25°C under agitation. This distinction determines equipment selection: NH-18 requires heated dissolution skids with jacket temperatures of 90°C and insulated transfer lines, whereas lower-hydrolysis grades can be handled in ambient-water make-down units.
Surface activity also differs across the hydrolysis range. Residual acetate groups increase hydrophobic character and reduce surface tension, so partially hydrolysed grades such as KH-17 behave as more effective emulsifiers and protective colloids in vinyl acetate and acrylic emulsion polymerisation. NH-18 has a higher aqueous surface tension and is selected in emulsion polymerisation primarily when the final film must exhibit lower water sensitivity and greater tensile strength after coalescence. The viscosity bracket of NH-18 provides sufficient molecular weight for film cohesion without the very high shear viscosity of NH-20, making it suitable for emulsion-polymerised adhesives where high-solids circulation and spray-drying are involved.
For textile warp sizing, NH-18 is dissolved to 6–10% solids and applied on slasher lines at 60–65°C. The higher molecular weight relative to low-viscosity PVA grades improves size film toughness but requires longer hot-water desizing. Desizing operations typically use 95°C water and 0.2–0.5 g/L non-ionic surfactant to overcome crystalline regions and remove the size film. Automatic sizing machines with ambient-water powder wetting cannot handle this grade reliably; a pre-slurry vessel or a separate cooking kettle with a high-shear disperser is required. In ceramic binder applications for alumina or zirconia green bodies, NH-18 at 0.5–2 wt% improves green strength before debinding. Thermal debinding in air above 500°C provides clean burnout, but the dried binder’s water resistance reduces moisture sensitivity of pressed parts during storage.
GOHSENOL NH-18 is not the correct grade for dosing systems that rely on ambient-water powder wetting or in-line eductor dispersion below 40°C. In those configurations, the granules remain as swollen gels, increase torque on the recirculation pump, and can block strainer baskets. When a fully hydrolysed grade is still required for end-use water resistance, the formulation should include a pre-dissolution step at 85–95°C in a jacketed tank with a rotor-stator mixer, followed by transfer through heat-traced pipework maintained above 75°C. If the process cannot accommodate heated dissolution, a lower-hydrolysis grade such as KH-17 or a cold-water-soluble PVA with a degree of hydrolysis below 82 mol% should be selected, accepting reduced film water resistance. The incompatibility of NH-18 with borate ions, glyoxal, glutaraldehyde, and strong oxidizers must also be considered; these species cause uncontrolled gelation or chain scission unless crosslinking is intentionally formulated and pH is buffered.
For food-contact paper and paperboard, GOHSENOL NH-18 is typically evaluated under 21 CFR 175.300 for resinous and polymeric coatings and 21 CFR 176.170 for components of paper and paperboard in contact with aqueous and fatty foods, subject to end-testing and residual monomer limits. Migration kinetics in polymer matrices are influenced by residual acetate content and crystallinity; extraction testing is required for the specific food type and temperature condition. The product is supplied under quality systems aligned with ISO 9001 and can be assessed under REACH Regulation (EC) No 1907/2006 for European Union inventory compliance. Heavy-metal content for electrical and electronic applications can be reviewed against RoHS Directive 2011/65/EU if the resin is used as a binder in laminated substrates, although this is not the primary application. Pre-drying at 70–80°C for 2–4 h in a desiccant dryer is recommended when ambient storage exceeds 60% RH and the granulate is intended for melt extrusion or cast film, because moisture uptake causes bubble formation and viscosity drift in the molten PVOH phase.
Substitution of NH-20 for NH-18 within the same hydrolysis band increases the 4% aqueous viscosity from 25.0–30.0 mPa·s to 35.0–45.0 mPa·s. In high-solid paper coating and adhesive lines, this raises pump pressure, coat weight transfer, and blade or rod metering resistance. The higher viscosity grade is selected when a thicker wet film or more shear viscosity is needed, but NH-18 is preferred for formulations above 10% solids where high-solids viscosity already limits circulation. Coaters operating with slot-die heads and mass-flow-controlled supply should recalibrate flow curves when switching between NH-18 and NH-20 because the viscosity difference at shear rates below 100 s⁻¹ shifts the coating window by approximately 3–5% in wet film thickness for a fixed pump speed. The pressure drop in laminar slot-die flow scales approximately with the low-shear viscosity ratio, so a 40% increase in 4% viscosity can produce a comparable increase in die cavity pressure at constant flow. Published data for this specific substitution is limited; however, the viscosity ratio measured under JIS K6726 provides a reliable first approximation for pump sizing and die pressure drop when the shear-rate dependence of the two grades is not available.
