| HS Code | 597008 |
| Product Name | GOHSENOL GH-22 |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White to pale yellow granular powder |
| Degree Of Hydrolysis | 99.0 - 99.8 mol% |
| Viscosity 4 Aqueous Solution 20 C | 22.0 ± 2.0 mPa·s |
| Average Degree Of Polymerization | Approximately 1700 |
| Molecular Weight | Approximately 75,000 |
| Ph 4 Aqueous Solution 20 C | 5.0 - 7.0 |
| Volatile Matter | 5.0% max |
| Ash Content | 0.5% max |
| Bulk Density | Approximately 0.6 - 0.7 g/cm³ |
| Solubility | Soluble in hot water; practically insoluble in organic solvents |
As an accredited GOHSENOL GH-22 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | GOHSENOL GH-22 polyvinyl alcohol is supplied as white granules in 25 kg laminated paper bags with polyethylene liner. |
| Container Loading (20′ FCL) | 20′ FCL: GOHSENOL GH-22 packed in 25kg bags, palletized, securely loaded for safe transport. |
| Shipping | GOHSENOL GH-22 is a water-soluble polyvinyl alcohol powder, typically non-hazardous for transport. Ship in sealed, moisture-proof bags or fiber drums. Avoid excessive dust and humidity. Store in a cool, dry place, protected from heat sources. Ensure proper labeling, no special dangerous goods requirements under standard shipping conditions. |
| Storage | Store GOHSENOL GH-22 in a cool, dry, well-ventilated area away from heat, open flames, and direct sunlight. Keep the container tightly closed when not in use to prevent moisture absorption, as the material is hygroscopic. Protect from physical damage and store separately from strong oxidizing agents and incompatible chemicals. |
| Shelf Life | Shelf life is typically 2 years from manufacture when stored unopened in a cool, dry place. |
Polymerization of vinyl acetate in continuous stirred-tank reactors using partially hydrolyzed polyvinyl alcohol as the sole protective colloid requires matching the colloid’s degree of blockiness to the initiator feed profile. GOHSENOL GH-22, supplied with a 4% aqueous viscosity of 44.0–52.0 mPa·s at 20°C under JIS K6726 and a hydrolysis range of 86.5–89.0 mol%, occupies a midpoint between low-viscosity grades that fail to prevent coalescence during monomer stripping and high-viscosity grades that push reactor discharge viscosity beyond the capacity of positive-displacement discharge pumps. The residual acetate distribution in this hydrolysis band produces a partially hydrophobic colloid that lowers aqueous surface tension without the heavy foam load associated with grades below 85 mol% hydrolysis, which matters in continuous reactors where liquid level fluctuations expose fresh colloid solution to the vapor space.
In production-scale continuous VAE (vinyl acetate-ethylene) plants using 10–20 m³ stirred autoclaves with external cooler loops, GH-22 is normally dissolved at 8–12 wt% solids in a separate jacketed vessel heated to 85–95°C and held for 30–45 min until filtration through a 60–80 mesh screen confirms complete solubilization. The protective colloid feed is then metered into the aqueous phase at rates corresponding to 4–8 wt% on total monomer feed, with the upper band recommended for high-ethylene-content grades above 20 wt% ethylene because the greater particle surface area generated during pressure polymerization consumes colloid more rapidly. Finished-dispersion Brookfield viscosity is monitored under ISO 2555, non-volatile content under ISO 3251, and pH under ISO 976. A recurring failure mode is slow gel accumulation on reactor baffles when the dissolution tank temperature drops below 80°C; undissolved microskins pass through the 60-mesh filter and nucleate gel domains downstream. The same effect is observed if the solution is held above 80°C for longer than 24 h, causing pH drift below 5.0 and increased color in the finished adhesive. The compound is incompatible with amine-based wetting agents at basic pH, which can accelerate vinyl acetate hydrolysis during storage and reduce wet bond strength. Terminal products include EN 204 D3 and D4 wood adhesives, VAE-modified cementitious mortars, and architectural coatings.
In blade coater formulations containing GOHSENOL GH-22 as a co-binder for double-coated wood-free papers, the critical limitation is the viscosity rise at blade shear rates near 10^5 s^-1, not the dry tensile strength of the cast film. The polymer is dissolved at 10–15 wt% solids and added to the coating color at 0.5–2.0 parts dry per 100 parts pigment, replacing up to 30% of the styrene-butadiene latex or oxidized starch. In this system the hydroxyl-rich PVA domains strengthen pigment-binder adhesion after drying, but the same hydrogen-bonding capacity that raises dry pick resistance also increases capillary viscosity and can produce blade bleeding on a 4.8 m wide machine if color temperature falls below 25°C. Surface strength is verified by IGT pick resistance according to ISO 3783, while high-shear rheology is measured with a cone-and-plate viscometer at 10^4–10^5 s^-1 to anticipate runnability.
Preparation of the cooked solution requires a jet cooker or indirectly heated stirred tank at 90–95°C for 20–30 min; cooling to 50–60°C before addition prevents latex destabilization and thermal shock. The coating color is screened through a 100-mesh pressure screen, and solids are adjusted to 58–62% for blade metering. Formulators use pre-coating basestock porosity data and pilot blade run-up curves to set the GH-22 dose, because the grade’s residual acetate content delays immobilization relative to fully hydrolyzed PVA, reducing water loss to the sheet but raising the risk of backwater enrichment. Terminal products include art paper, folding boxboard, and label face stock.
On air-jet looms operating above 800 picks/min, the size film must balance high tensile modulus against abrasion resistance at reed and heald contact points. GOHSENOL GH-22 is dissolved at 8–12 wt% solids for polyester/cotton blends and applied in a multi-cylinder sizing machine at size box temperatures of 70–80°C; squeeze pressure is normally maintained between 0.2 MPa and 0.4 MPa to achieve an add-on of 8–15% by yarn mass. The partial hydrolysis range of 86.5–89.0 mol% gives cold-water swellability that supports controlled desizing without the caustic scouring required for fully hydrolyzed PVA grades. Film properties are evaluated using yarn tensile strength according to ASTM D2256 and loom-shed abrasion simulation, because cyclic loading at 10–20 Hz cannot be replicated by single-end tensile curves.
Size cooking is performed in pressure cookers at 110–120°C for 15–20 min when starch is co-cooked; separate PVA dissolution before starch addition prevents uncontrolled lumping and viscosity drift. The limiting operational condition is desizing effluent: residual PVA increases chemical oxygen demand, so the size formulation must not exceed 12 wt% GH-22 unless an ultrafiltration recovery unit is installed. In some plants, the size box is maintained at pH 6–7 because acidic conditions below pH 5 promote acid-catalyzed hydrolysis of the residual acetate groups, shifting the desizing profile and lowering film abrasion resistance. Terminal fabrics include shirting, workwear, and bed linen.
For remoistenable adhesive manufacturing, the polymer is dissolved as a 25–35 wt% aqueous solution in jacketed sigma-blade mixers heated to 85–90°C, then cast onto envelope flap stock or label backing at coat weights from 5 g/m² to 15 g/m² dry. GOHSENOL GH-22 is selected because the narrow hydrolysis band maintains rapid water re-wetting after storage at 25°C and 50% relative humidity, whereas fully hydrolyzed grades can become slow-tack after cyclic humidity exposure. The dried film must pass blocking tests at 40°C and 70% relative humidity for 72 h without fiber tear. Borax or boric acid may be post-added at 0.5–2.0 parts per 100 parts PVA solids to increase wet tack, but the operator must observe a gelation threshold: additions above 2.0 parts borax per 100 parts GH-22 produce a non-coatable gel at 25°C.
Viscosity of the finished adhesive is measured at 20 rpm with a Brookfield viscometer according to ISO 2555, and total solids by ISO 3251. For food-contact envelope gum used on indirect packaging, the dried adhesive complies with 21 CFR 175.105 if all other formulation components are similarly compliant. The terminal articles are envelopes, stamps, and paper tapes.
Because vinyl chloride suspension polymerization is conducted at 50–70°C in 30–60 m³ stirred reactors under a two-phase liquid-liquid dispersion, the secondary dispersant must stabilize monomer droplets after the primary dispersant has fixed the initial interface. GOHSENOL GH-22 is metered as a 4–6 wt% aqueous solution and used at total dispersant loadings of 0.08–0.15 wt% on vinyl chloride monomer in combination with a fully hydrolyzed primary grade. The partially hydrolyzed acetate sequences in the 86.5–89.0 mol% range reduce surface tension more effectively than fully hydrolyzed PVA, while the 44.0–52.0 mPa·s viscosity band does not generate the excessive continuous-phase viscosity that would impede monomer droplet circulation near the reactor baffles. Control is verified by sieve retention and plasticizer absorption under ISO 1624 or ASTM D1755; a dispersant imbalance alters the population of 125 µm and 63 µm sieve fractions, which directly changes extrusion dry-blend porosity.
Operational experience shows that pre-dissolution at 85°C is mandatory because residual undissolved PVA particles act as secondary nucleation sites, producing a coarse tail in the final resin. Storage of the feed solution above 40°C is recommended to prevent microbial growth, but holding above 80°C for more than 24 h can yellow the solution and shift pH below 5.0. End products are suspension PVC resins for rigid pipe, window profiles, and medical tubing.
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GOHSENOL GH-22 is a partially hydrolysed polyvinyl alcohol resin supplied as free-flowing granules. The grade is defined by its aqueous solution rheology: a 4% solution in deionized water at 20°C has a specified viscosity of 44.0–52.0 mPa·s when tested according to JIS K6726. Its degree of hydrolysis is 86.5–89.0 mol%, leaving approximately 11–13.5 mol% residual acetyl groups. This places GH-22 in the medium-molecular-weight, partially hydrolysed class. The residual acetyl content reduces interchain hydrogen bonding, depresses crystallinity, and permits cold-water dissolution, but it also lowers ultimate tensile strength and water resistance relative to fully hydrolysed grades such as those in the NH series.
Routine certificate-of-analysis values include volatile matter not exceeding 5.0%, sulphated ash not exceeding 0.5%, and pH of a 4% aqueous solution in the range 5.0–7.0. These specifications are measured on the granular resin after drying at 105°C or by the procedure specified in JIS K6726. Users handling the product in humid plants should account for hygroscopic pickup: at relative humidity above 60%, moisture can exceed specification, leading to weighing errors and lump formation in silos or bag-dump hoppers.
Solution preparation starts with dispersion in cold water at 20–30°C under mechanical agitation. The mixture is then heated to 85–90°C and held for 30 min to complete dissolution. A jacketed stainless-steel vessel with a saw-tooth disperser operating at a tip speed of 3–5 m/s provides sufficient shear for dispersion without causing microgel formation after full dissolution. Overheating above 95°C, especially at the vessel wall, can form gel skins that appear as fisheyes in downstream coating or film processes.
| Parameter | Specification | Test Method |
|---|---|---|
| 4% solution viscosity at 20°C | 44.0–52.0 mPa·s | JIS K6726 |
| Degree of hydrolysis | 86.5–89.0 mol% | JIS K6726 |
| pH of 4% solution | 5.0–7.0 | JIS K6726 |
| Volatile matter | ≤5.0% | JIS K6726 |
| Sulphated ash | ≤0.5% | JIS K6726 |
The viscosity specification is the primary quality-control parameter for molecular weight consistency. Viscosity deviation of ±3 mPa·s within the specification window can alter thickening efficiency; for critical emulsion polymerization or coating processes, incoming lots should be pre-tested in a laboratory mixer at fixed solids. The degree of hydrolysis affects solubility, surface activity, and adhesive performance more strongly than viscosity in partially hydrolysed grades. A lot at the upper end of the hydrolysis range may require slightly higher dissolution temperature, while a lot at the lower end may produce lower water resistance in dried films.
GH-22 is used as a protective colloid in semicontinuous emulsion polymerization of vinyl acetate, vinyl acetate-ethylene, and vinyl acetate-acrylic monomers. At addition levels of 2–6 wt% based on total monomer, the resin adsorbs at the monomer-water interface and provides steric stabilization of growing polymer particles. A lower-viscosity grade such as GH-17 reduces solution thickening but may require a higher addition level or more efficient agitation to prevent coagulum. A higher-viscosity grade such as GH-23 improves stabilization and film cohesion but raises continuous-phase viscosity and can reduce heat transfer at high conversion.
In a stirred stainless-steel reactor with a retreat-curve impeller running at tip speed 2.5–3.5 m/s, the cooled-wall film becomes a processing limit when its apparent viscosity exceeds approximately 1000 mPa·s. GH-22 at 3 wt% on monomer in a model 55% non-volatile dispersion is reported in supplier application literature to produce lower continuous-phase viscosity than GH-23 at equal solids; nevertheless, published data for a given reactor configuration is limited, and pilot-scale confirmation is required before changing protective colloid grade.
Residual acetyl groups in GH-22 reduce the extent of free-radical grafting of polyvinyl acetate onto the polyvinyl alcohol backbone compared with fully hydrolysed polyvinyl alcohol. This lowers the formation of insoluble graft-coagulum in continuous operation. Initiation with ammonium persulphate at 0.1–0.5 wt% on monomer releases acidity; the pH of the emulsion can fall below 3.5 if no buffer is used, reducing colloid stability and increasing coagulation. Sodium acetate at 0.1–0.3 wt% on monomer is sufficient to maintain pH between 4.5 and 5.5 in many formulations. Temperature control at 65–75°C during the vinyl acetate feed stage is typical; higher temperatures accelerate initiator decomposition and can widen particle size distribution.
As the protective colloid concentration rises from 2% to 4% on monomer, the mean particle size of a vinyl acetate homopolymer dispersion decreases and low-shear viscosity increases. This trade-off is exploited to adjust particle size without adding surfactant, but it is not linear. Above 6 wt% on monomer, the viscosity gain frequently exceeds the stability benefit, and the reactor may require additional cooling because of higher torque. Published data for this specific grade in vinyl acetate-ethylene formulations at reactor pressure 50–80 bar is limited; manufacturers generally evaluate the grade first in a pilot loop at low ethylene content.
In paper pigment coating, GH-22 is mixed into clay or calcium carbonate dispersions as a co-binder and water-retention agent. Addition levels of 0.5–1.5 wt% on dry pigment raise low-shear viscosity and reduce binder migration during hot-air drying. The outcome is a more uniform gloss profile and fewer blade scratches on a coater running at 1200 m/min. Above 2.0 wt% on pigment, the high-shear viscosity can exceed the operating window of a blade coater, and the coating colour may show excessive dilatancy. For textile warp sizing, the same partially hydrolysed structure yields a flexible film on cotton and polyester-cotton yarns. Desizing is accomplished in hot water at 60–80°C with mild alkali, which is an advantage over fully hydrolysed grades that require more aggressive washing. Published mill data for GH-22 in air-jet weaving at 800–1000 picks/min is limited; blends with starch or polyacrylic acid are normally used to balance film toughness and cost.
Unsupported films cast from GH-22 are tested according to ASTM D882-18 after conditioning at 23°C and 50% RH. The partially hydrolysed structure lowers tensile strength and raises elongation relative to fully hydrolysed polyvinyl alcohol of equivalent viscosity because the residual acetyl groups act as internal plasticizers. Differential scanning calorimetry under ISO 11357-2 places the glass transition temperature of this hydrolysis range between 60°C and 70°C. A film cast from a 10% aqueous solution at 40 μm dry thickness dissolves in water at 20°C within 30–60 min under gentle agitation. At 85% RH, oxygen transmission increases relative to 0% RH because water molecules disrupt interchain hydrogen bonds. This humidity sensitivity is a known trade-off for partially hydrolysed grades; barrier coatings or lamination are required when low oxygen transmission is needed in moist environments. Plasticizer addition, such as glycerin at 5–10 wt% on polymer, lowers film modulus and increases elongation but raises moisture uptake and blocking tendency. Published data for GH-22 in single-layer water-soluble packaging is limited; film converters should generate a grade-specific property matrix rather than rely on generic polyvinyl alcohol film values.
Within the partially hydrolysed GOHSENOL GH series, GH-22 occupies the medium-viscosity position between GH-17 and GH-23. All three grades share the hydrolysis range 86.5–89.0 mol%, so solubility behavior is similar, but molecular weight differences change solution viscosity, film strength, and emulsion stabilization efficiency. Higher viscosity improves wet-film cohesion and particle stabilization but raises mixer torque and can slow dissolution. GH-22 is selected when GH-17 lacks sufficient film strength or protective power, and GH-23 creates excessive viscosity in high-solids formulations or in coating colour.
| Grade | 4% solution viscosity at 20°C | Hydrolysis range | Selection consequence |
|---|---|---|---|
| GH-17 | 25.0–31.0 mPa·s | 86.5–89.0 mol% | Lowest thickener; suited to high-solids adhesives and emulsions where viscosity must remain low |
| GH-22 | 44.0–52.0 mPa·s | 86.5–89.0 mol% | Balanced thickening, film strength, and emulsion stabilization |
| GH-23 | 50.0–58.0 mPa·s | 86.5–89.0 mol% | Highest of the three; improves wet-film cohesion but increases mixer torque and solution viscosity |
The difference from fully hydrolysed grades is more significant than the difference within the GH series. Fully hydrolysed polyvinyl alcohol, typically above 98 mol% hydrolysis, requires hot water above 80°C for dissolution, produces films with higher tensile strength and lower humidity sensitivity, and provides better barrier performance under moist conditions. Conversely, fully hydrolysed grades have weaker adhesion to hydrophobic substrates and lower flexibility. For remoistenable adhesives, paper sizing, and water-soluble packaging, the partially hydrolysed structure of GH-22 is functionally preferable. For moisture-resistant paper coatings or blown film requiring low oxygen transmission at high humidity, a fully hydrolysed grade is technically more appropriate.
For indirect food contact, GOHSENOL GH-22 is referenced under FDA 21 CFR 175.105, 176.170, and 176.180 as a component of adhesives and paper and paperboard coatings, subject to intended-use restrictions. In the European Union, the finished article must comply with Regulation (EU) No 10/2011; polyvinyl alcohol is a polymer, but residual vinyl acetate monomer migration must be controlled through overall migration testing and monomer-specific verification if required by the finished article. Users should obtain lot-specific conformity certificates because migration performance depends on coating weight, crosslinking, and food type.
Storage above 60% RH increases granule moisture beyond 5.0% and may alter feed consistency. Bags should remain sealed and storage temperature should remain below 30°C. When moisture exceeds specification, pre-drying at 60–80°C for 2–4 h with dust-controlled air is used. The dried resin forms combustible dust; conveying and dust-collection equipment should follow local dust explosion standards. Avoid exposing aqueous GH-22 solutions to borate ions, because gelation occurs at pH above 8.0 even at low borate concentration. Strong acids and bases accelerate hydrolysis of acetate groups, shifting solution viscosity and pH. Sustained processing above 200°C degrades the polymer with release of acetic acid and unsaturated volatiles; this grade is not intended for unplasticized melt extrusion, and published data for such processing is limited.
