| HS Code | 899320 |
| Chemical Name | Poly(vinyl alcohol) |
| Cas Number | 9002-89-5 |
| Molecular Formula | (C2H4O)n |
| Appearance | White to pale yellow granular powder |
| Odor | Odorless |
| Degree Of Saponification Hydrolysis | 86.5 - 89.0 mol% |
| Viscosity 4 Aqueous Solution At 20 C | 23.0 - 30.0 mPa·s |
| Ph 4 Aqueous Solution At 20 C | 5.0 - 7.0 |
| Specific Gravity Density | Approximately 1.27 g/cm³ at 20°C |
| Solubility | Soluble in water; practically insoluble in organic solvents |
| Ash Content | ≤ 0.5% |
| Volatile Content | ≤ 5.0% |
| Melting Point | Approximately 180 - 230°C with decomposition |
As an accredited GOHSENOL GH-23 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | GOHSENOL GH-23 is supplied as a white powder in 20 kg multi-layer paper bags with polyethylene liner for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL container loading of GOHSENOL GH-23: palletized bags securely stowed, ventilated, protected from moisture, ensuring safe transport and handling. |
| Shipping | GOHSENOL GH-23 (polyvinyl alcohol) is a non-hazardous powder. Ship in dry, clean, well-sealed packaging to prevent moisture absorption and contamination. Keep away from strong oxidizers, store in a cool, ventilated area, and handle to minimize dust. No special transport classification required under standard regulations. |
| Storage | Store GOHSENOL GH-23 in its original, tightly sealed container in a cool, dry, well-ventilated area. Protect from moisture, direct sunlight, and heat sources. Keep away from oxidizing agents and open flames. Avoid generating dust during handling. Under proper conditions, shelf life is typically maintained for several years. |
| Shelf Life | Shelf life: 24 months from manufacture if stored in original sealed container in a cool, dry place. |
GOHSENOL GH-23 is a partially hydrolyzed polyvinyl alcohol with a 4% aqueous solution viscosity of 44–52 mPa·s at 20 °C as determined by JIS K6726 and a degree of hydrolysis of 86.5–89.0 mol%. The grade is applied in cold-water-soluble conversion routes, colloidal stabilization, and bonding where the processing window is limited by dissolution temperature, drying humidity, and melt residence time. The following scenarios are restricted to established downstream applications: emulsion polymerization protective colloid, paper surface sizing, textile warp sizing, water-soluble cast film converting, remoisturable adhesive coating, and thermoplastic melt compounding.
In semibatch vinyl acetate homopolymer and vinyl acetate-ethylene emulsion polymerization, GOHSENOL GH-23 is charged as the primary protective colloid. The aqueous phase is prepared at 8–12 wt% polymer solids in deionized water with jacket heating to 80–90 °C for 90–120 min; incomplete dissolution below 75 °C produces microgel seeds that elevate 100-mesh coagulum above 0.2 wt%. After cooling to 45–55 °C, the reactor charge contains 3.0–5.5 wt% GOHSENOL GH-23 relative to total monomer mass for wood adhesive lattices, and 2.0–4.0 wt% for low-viscosity paint and nonwoven binder grades. A stirred stainless steel reactor of 10–25 m³ working volume is typically equipped with a 3-blade retreat-curve turbine at 80–120 rpm and a reflux condenser sized for monomer addition rates of 0.15–0.30 kg/min. Redox initiation with hydrogen peroxide and sodium formaldehyde sulfoxylate at 65–75 °C produces batch-to-batch latex Brookfield viscosity in the range of 2,000–8,000 mPa·s at 25 °C. Process control should maintain pH 4.2–5.8 via buffered delayed addition; excursions above pH 6.2 reduce graft efficiency onto the PVA backbone and increase water sensitivity of the dried film. Residual vinyl acetate monomer is typically reduced to <1,000 mg/kg through a post-oxidation stage with tert-butyl hydroperoxide. For compliance, the compounded adhesive or coated substrate falls under FDA 21 CFR §176.170 for aqueous and fatty food contact, FDA 21 CFR §176.180 for dry food contact, and FDA 21 CFR §175.105 for adhesive components; each formulated system must be validated by end-use extraction testing rather than by grade certification alone. Representative terminal products are EN 204 D3 woodworking dispersions, interior architectural paint binders, and high-wet-strength nonwoven wipes.
At a rod-metering size press running 800–1,500 m/min, GOHSENOL GH-23 is introduced into the starch solution at 0.8–2.2 wt% of the wet size-press pick-up formulation, replacing 10–30% of oxidized corn starch solids. The working solution is held at 45–60 °C and diluted to 8–14% total solids to maintain a size press viscosity of 40–120 mPa·s at 50 °C, measured on a Brookfield LV viscometer at 60 rpm. The addition raises low-shear viscosity more than high-shear viscosity, which is a critical distinction when rod pressure is adjusted to control film thickness. Surface strength measured by ISO 3783 IGT pick test generally improves by 15–35% over a starch-only control when GH-23 constitutes 1.0–1.8 wt% of the formulation; below 0.4 wt%, pick improvement is frequently not statistically separable from basis-weight variation. Mill trials have recorded lower fold cracking when the PVOH fraction above 1.5 wt% is paired with a metering rod pressure below 120 kN/m; higher pressure strips the size film and creates skip-coat defects on high-ash recycled liner. Compliance for food-contact paperboard is evaluated under FDA 21 CFR §176.170 and FDA 21 CFR §176.180, with migration testing designed for the specific board construction; EN 71-3 screening is applied when the finished paper enters children's printed matter. Terminal products include inkjet coating base, folding carton board, and high-ring-crush recycled liner.
Operating data from cotton-polyester warp sizing lines show that replacement of 30–50% of a native starch size with GOHSENOL GH-23 shifts the size bath viscosity and requires a lower squeeze pressure to maintain a uniform size add-on. A typical size mix is prepared at 8–14% total solids with 4–8 wt% GH-23 based on total dry size solids, 55–70 wt% thin-boiling starch, 10–20 wt% acrylic copolymer, and 1–3 wt% wax or ester lubricant. The size liquor is cooked at 90–95 °C for 30–45 min in a pressure cooker and maintained at 80–88 °C in the size box of a slasher. Slasher squeeze rollers are operated at 8–20 kN/m linear pressure; higher pressure reduces size add-on and increases hairiness of polyester-rich yarns. Desizing of the greige fabric uses hot-water washing at 85–95 °C with 0.5–1.5 g/L nonionic scour, followed by alkali or oxidative stage if starch portions have retrograded. Wastewater COD from PVA desizing is typically controlled by ultrafiltration recovery or advanced oxidation; ZDHC MRSL v3.1 does not list PVA as a banned substance, but discharge permits may set COD limits below 500 mg/L. End products include shirting, sheeting, and denim fabric. Compliance for the finished textile is assessed under OEKO-TEX Standard 100 Annex 4 or an equivalent brand-specific RSL protocol; PVA itself is not a detectable residue in the final fabric when desizing removal exceeds 98%.
GOHSENOL GH-23 is used as the base resin in solution-cast water-soluble film formulations for unit-dose detergent sachets, agrochemical water-soluble bags, and embroidery backing. GH-23 constitutes 75–85 wt% of the dry film formulation. The casting solution is prepared at 15–25 wt% solid in deionized water, heated to 85–95 °C under slow agitation, then deaerated under −0.08 to −0.1 MPa vacuum for 30–60 min. Plasticizer content ranges from 10–20 phr, typically glycerol, sorbitol, or a trimethylolpropane blend, with 0.1–0.5 phr nonionic surfactant and 0.3–1.0 phr release agent. The solution is cast at 25–40 mm wet film thickness onto a stainless steel belt heated to 75–85 °C, followed by drying zones at 90–130 °C to a residual moisture of 4–8 wt%. Film of 35–75 µm thickness is slit and converted under 45–55% RH; conversion below 35% RH raises edge cracking, and conversion above 65% RH creates blocking. Cold-water disintegration of film made from GH-23 at 10 °C is slower than at 20 °C, and agitation rate and water hardness must be specified for CIPAC MT 184 dissolution testing. Published data for this specific configuration is limited when immersion below 5 °C is specified; plant validation is required. Compliance for detergent packaging involves compatibility testing under the formulated surfactant system and packaging classification under the UN Model Regulations; for agrochemical sachets, the film is evaluated under CIPAC MT 184 and the applicable FAO/WHO specification for water-soluble packaging. Terminal products are detergent unit-dose pouches, water-soluble agrochemical bags, and transfer printing supports.
Remoisturable adhesive production for envelope flaps, stamps, and tape backings roller-coats or slot-die coats an aqueous formulation containing 20–35 wt% GOHSENOL GH-23, 30–50 wt% dextrin or borated dextrin, 5–15 wt% plasticizer, and 0.3–1.5 wt% defoamer at 15–30 g/m² dry coat weight, then dries in a forced-air tunnel at 70–110 °C with web temperature held below 90 °C to prevent surface skinning, before rewet tack at 25 °C and 50% RH is evaluated by ASTM D1876 T-peel and blocking is assessed at 40 °C and 80% RH, with compliance under FDA 21 CFR §175.105 and FDA 21 CFR §176.170 for paper-based food-contact articles.
Thermoplastic conversion of GOHSENOL GH-23 is executed on a co-rotating twin-screw extruder with L/D 40:1–52:1 and a vacuum vent at the 70% length position. PVA powder is pre-dried to <0.3 wt% moisture and fed at 20–60 kg/h while a plasticizer blend of glycerol and sorbitol is injected into zone 3 at 10–25 phr; barrel temperatures from feed to die are set at 90/170/190/195/185 °C. Screw speed is maintained at 150–300 rpm; torque must remain below 80% of drive capacity to avoid crosslinking at residence times beyond 90 s. Melt pressure at the die is typically 2–8 MPa, and melt temperature should not exceed 210 °C. The compounded pellets are processed by blown film or cast film into water-soluble packaging film, injection molded into dissolvable articles, or used as dissolvable mandrels in fiber-reinforced composites. Mechanical tests follow ISO 527-3 for cast film tensile properties and ISO 1133-1:2022 for melt mass-flow rate at 190 °C and 21.6 kg. Compliance is application-dependent; for food-contact use, EU Regulation (EU) No 10/2011 verification of plasticizer and additive migration applies. Published data for this specific configuration is limited at moisture levels above 0.5%; pre-drying is mandatory before extrusion.
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GOHSENOL GH-23 is a partially hydrolyzed polyvinyl alcohol grade supplied as a white powder for aqueous processing. The product belongs to the high-viscosity portion of the GOHSENOL G-series and is specified by its 4% aqueous solution viscosity and degree of hydrolysis. In downstream operations, GH-23 is selected where elevated solution viscosity, partial cold-water solubility, and high dry-film cohesion are required simultaneously. Representative application areas include vinyl acetate emulsion polymerization, remoistenable adhesives, paper surface sizing, and textile warp sizing. The material is characterized under JIS K6726, the polyvinyl alcohol test method used for viscosity, saponification degree, volatile matter, ash, and pH. Because the grade is partially hydrolyzed, it retains a controlled residual acetate content, which reduces crystalline order relative to fully hydrolyzed grades and modifies solubility, adhesion, and film mechanics.
GH-23 is defined by two certificate-of-analysis parameters: degree of hydrolysis and dynamic viscosity. The hydrolysis range is 86.5–89.0 mol%, placing the polymer in the partially hydrolyzed class. The nominal degree of polymerization is approximately 2,300, which places the material in the high-molecular-weight portion of the GOHSENOL range. The 4% aqueous solution viscosity at 20 °C is specified as 44.0–52.0 mPa·s under JIS K6726. Lower-viscosity partially hydrolyzed grades fall below the 44.0 mPa·s boundary, while fully hydrolyzed grades are specified above 98.0 mol% hydrolysis. GH-23 therefore provides more thickening per unit mass and higher wet-film strength than lower-viscosity partial grades at equivalent solids, but requires more controlled mixing to prevent lump formation.
| Parameter | Typical specification | Test basis |
|---|---|---|
| Degree of hydrolysis | 86.5–89.0 mol% | JIS K6726 |
| Viscosity, 4% aqueous solution at 20 °C | 44.0–52.0 mPa·s | JIS K6726 |
| Volatile matter | max 5.0% | JIS K6726 |
| Ash | max 0.5% | JIS K6726 |
| pH | 5.0–7.0 | JIS K6726 |
In certificate-of-analysis practice, the 4% solution viscosity is determined after complete dissolution and controlled cooling. Any deviation in solution temperature or concentration shifts the reported viscosity; laboratories therefore calibrate the reading against a reference polyvinyl alcohol solution and verify concentration by non-volatile solids content. The narrow hydrolysis range is intended to limit batch-to-batch variation in cold-water solubility and adhesive performance, but not all end-use responses are captured by hydrolysis and viscosity alone. Molecular-weight distribution, residual sodium acetate, and drying history can influence solution clarity and film appearance in continuous operations.
Solution preparation in production-scale mixing vessels requires attention to particle wetting and hydration kinetics. The powder is added to a cold or ambient water phase under high-shear agitation, then the batch is heated to 80–90 °C and held until the solution clarifies. Direct addition to hot water without prior dispersion can form swollen gel aggregates that are slow to dissolve because the hydrated outer layer of the high-viscosity grade impedes water ingress. For batch sizes above 1,000 L, an eductor or powder-induction hopper is preferred over dumping directly into an open tank. Final viscosity is checked after cooling to 20 °C with a Brookfield LV or equivalent rotational viscometer. At ambient relative humidity above 60%, moisture uptake can reduce flowability and produce lumps; sealed bags and conditioned air metering are recommended.
Dissolution vessels handling 10–15 wt% stock solutions should have bottom-entry high-shear mixing or an inline rotor-stator loop to prevent powder accumulation at the liquid surface. Defoaming may be required if air entrainment from the high-viscosity vortex creates foam that interferes with level control. Stock solutions held beyond 48 h at ambient temperature should be checked for viscosity loss or microbial growth, especially when starch or protein co-binders are not present. If a preservative is required, compatibility with the anionic or nonionic latex components used downstream must be confirmed.
In vinyl acetate and vinyl acetate-ethylene emulsion polymerization, GH-23 is metered as a pre-dissolved aqueous solution into the reactor to act as a protective colloid. Typical use rates range from 2–6 wt% on total monomer, depending on target latex viscosity and particle-size distribution. The colloid fraction partially grafts with the polymerizing monomer and forms a steric barrier that limits coagulum formation. Jacketed reactors with pitched-blade or anchor impellers and jacket temperatures of 60–85 °C maintain stable dispersion because the solution viscosity of GH-23 helps transfer shear stress across the aqueous phase. Compared with a lower-viscosity partially hydrolyzed grade at the same solids level, GH-23 increases latex low-shear viscosity more strongly, allowing a reduction in post-polymerization thickener addition. The same viscosity contribution can reduce heat-transfer efficiency at high conversion if jacket turnover or recirculation-loop capacity is already limited.
In vinyl acetate homopolymer latex production, the protective colloid is often split between the initial reactor charge and a delayed feed. A higher proportion of GH-23 in the initial charge tends to produce smaller particle diameters and higher latex viscosity, while delayed addition supports larger particles and lower low-shear viscosity. The optimal split is best determined in a pilot reactor rather than inferred only from solution viscosity, because latex particle size and coagulum formation depend on initiator type, temperature profile, and monomer feed rate. Coagulum is screened through a 150 µm filter; an upward drift in filter residue indicates colloid insufficiency or initiator imbalance. Laser diffraction particle-size analysis and residual-monomer gas chromatography are more reliable end-point controls than Brookfield viscosity alone, because viscosity drift can originate from either under- or over-stabilized emulsion systems.
Adhesive and paper-converting applications use GH-23 as a high-cohesion binder where remoistenability and low-temperature activation are required. For remoistenable tapes and envelope seams, the polymer is applied from a 10–20 wt% aqueous solution by roll coater and dried in a convection or infrared tunnel. The residual acetate groups lower the crystalline melting point relative to fully hydrolyzed PVOH, permitting faster rewetting of the dry film. Adhesive film performance is measured by T-peel tests under ASTM D1876 or ISO 11339 after conditioning at 23 °C and 50% relative humidity. At higher humidity, absorbed water plasticizes the film and increases peel elongation, so test values should not be interpreted without the conditioning history.
In surface sizing of paper and board, GH-23 is blended with oxidized starch or a styrene-acrylate size at a puddle or film press. The addition rate is typically 0.5–2.0% dry polymer on dry fiber. The high-viscosity solution reduces size penetration into the sheet and deposits a more continuous surface film, which contributes to surface strength measured by IGT pick velocity or wax pick number. At press speeds above 600 m/min, film splitting at the roll nip is affected by the viscoelastic character of the GH-23–starch blend and may require adjusted solids or partial replacement with a lower-viscosity co-binder. Water resistance is measured by Cobb 60 s tests according to TAPPI T441 or ISO 535, not by visual inspection alone.
Substitution of a fully hydrolyzed grade with GH-23 changes solubility, crystallinity, and mechanical response. Fully hydrolyzed PVOH is specified above 98.0 mol% hydrolysis and generally requires heating to 90–95 °C for complete dissolution. GH-23, at 86.5–89.0 mol% hydrolysis, dissolves at lower temperatures and provides more rapid cold-water swelling, but its equilibrium film strength is lower than a fully hydrolyzed grade of comparable molecular weight. In textile warp sizing, the partially hydrolyzed structure improves adhesion to hydrophobic polyester and improves size removal in desizing baths. On water-jet looms, the sizing formulation may contain GH-23 at 8–15 wt% solids in the size box, with after-waxing or oiling to reduce yarn friction over metal reed dents. Yarn end-break rate per 10,000 m is the more operationally significant control than size-box viscosity alone.
| Operating property | GOHSENOL GH-23 | Fully hydrolyzed high-viscosity PVOH | Lower-viscosity partially hydrolyzed PVOH |
|---|---|---|---|
| Hydrolysis degree | 86.5–89.0 mol% | above 98.0 mol% | 86.5–89.0 mol% |
| 4% aqueous viscosity at 20 °C | 44.0–52.0 mPa·s | grade-dependent; may overlap | below 44.0 mPa·s |
| Dissolution temperature for rapid solution make-up | 80–90 °C | 90–95 °C | lower cold-water dissolution threshold |
| Film strength at equal thickness | moderate | higher | lower |
| Water sensitivity of dried film | higher than fully hydrolyzed grade | lower | higher |
In cast film, GH-23 yields lower tensile strength and lower water resistance than fully hydrolyzed grades. If moisture-barrier or solvent resistance is critical, a fully hydrolyzed or crosslinked grade should be specified. Film mechanical properties from solution-cast samples are evaluated under ASTM D882 or ISO 527-3 after conditioning at 23 °C and 50% relative humidity. The exact values depend on drying rate, residual solvent, and plasticizer content; data from different laboratories are not comparable unless the conditioning and casting procedure is fully reported.
GH-23 exhibits non-Newtonian solution response above approximately 8–10 wt% solids, with apparent viscosity dependent on shear history and temperature. Rotational viscometry at 20 °C under controlled spindle speed is used for quality control; capillary or falling-ball methods are not interchangeable because the polymer solution is viscoelastic. Dried films have tensile properties that vary with plasticizer content and conditioning humidity. At 50% relative humidity, the film absorbs enough moisture to reduce tensile modulus; at 80% relative humidity, film blocking can occur. Heat-sealing and blocking resistance are therefore specified with reference to a conditioning standard and a defined contact pressure.
Borate compounds such as sodium tetraborate crosslink the 1,3-diol units, and additions as low as 0.1–0.5% on dry polymer can produce a sharp viscosity increase or localized gel formation. This interaction is exploited in some adhesives and temporary coatings but is an incompatibility in standard solution storage, where borate contamination can produce filter-plugging gels. Strong acids and bases should also be avoided because they accelerate acetate hydrolysis or chain scission at elevated temperature. In adhesive and coating formulations that contain starch, calcium carbonate, or clay, the influence of these dispersed solids on measured viscosity should be separated from the solution viscosity of GH-23 to avoid incorrect adjustment of coat-weight controls.
In film and adhesive formulations, glycerin, sorbitol, and polyethylene glycol are used as plasticizers with GH-23 because the residual acetate group is compatible with polar plasticizers. Plasticizer addition in the 10–30 wt% range on dry polymer reduces the glass transition temperature and increases elongation, but excess plasticizer can cause surface exudation and reduced blocking resistance. The effective glass transition temperature is humidity-dependent; conditioned samples at 23 °C and 50% relative humidity show lower values than dry-state DSC data, so published glass transition values should be cited with the conditioning environment.
Handling and compliance documentation for GH-23 should be consulted for food-contact and environmental status. The product may be used in adhesives and paper coatings that fall under FDA 21 CFR 175.105, 176.170, and 176.180, subject to the extraction limits and end-use conditions stated in those sections. For EU shipments, the grade is covered by REACH registration and should be checked against national worker-exposure limits for polyvinyl alcohol dust. Dust explosion risk is lower than many organic fine powders, but housekeeping and grounding of powder-transfer lines are standard. The powder should be stored below 60% relative humidity and below 40 °C to prevent caking. Material safety data sheets should be reviewed before specifying GH-23 in indirect food-contact packaging, and migration testing is required where national legislation imposes specific migration limits for vinyl acetate-derived substances.
