GOHSENOL GH-23

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.

What Controls Surface Strength at 1,200 m/min When GH-23 Enters the Size Press?

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%.

If Cold-Water Disintegration Below 10 °C Is Required for Unit-Dose Sachets

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 Drying and Rewet Tack without Blocking

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.