GOHSENOL NL-05

In vinyl acetate-ethylene (VAE) and vinyl acetate-acrylic emulsion reactors, GOHSENOL NL-05 is introduced as a pre-dissolved aqueous colloid at 8.0–10.0 wt% solids. The solution is prepared in a jacketed vessel at 60–90°C with a turbine impeller running at 200–400 rpm, then cooled to 35–45°C before metering into the monomer-charged stainless-steel reactor. The grade is a partially saponified polyvinyl alcohol with nominal degree of hydrolysis 86.5–89.0 mol% and nominal viscosity 4.5–6.5 mPa·s as a 4.0% aqueous solution at 20°C tested under JIS K6726. In VAE polymerisation, the protective colloid governs primary-particle nucleation and later steric stabilisation after grafting onto latex particle surfaces. At a use level of 1.0–2.5 wt% on total monomer, NL-05 permits dispersion solids of 55–60% while maintaining Brookfield viscosity below 1,200 mPa·s at 25°C by ISO 2555:2018. Redox initiation is operated at 75–95°C and reactor pressure 15–45 bar. Agitation is held at retreat-curve impeller tip speeds of 4.5–6.5 m/s during the high-holding phase. Above 7.0 m/s, shear-induced graft chain desorption raises latex viscosity and increases filter-blocking gel measured on a 100-mesh screen. The hydrolysis window of 86.5–89.0 mol% leaves sufficient hydroxyl density for surface anchoring while limiting excessive hydrogen-bond-driven viscosity build in high-solids lattices.

In emulsion systems containing anionic sulfosuccinate or alcohol ether sulfate surfactants, NL-05 is typically blended at a colloid-to-surfactant solids ratio of 2:1 to 4:1. This ratio affects coagulum formation and shelf stability. Coagulum after 100-mesh filtration is controlled below 500 ppm when the ratio is maintained and reactor oxygen content is reduced to < 0.5 ppm before initiator injection. The aqueous phase should be demineralised to conductivity < 10 µS/cm. Calcium and magnesium ions above 50 ppm as CaCO₃ can interact with residual acetate groups and generate microgel that blocks coalescence and produces coarse fraction. NL-05 is not recommended as the sole stabilizer for coarse-particle emulsion products above 1,000 nm target diameter because its low molecular weight provides insufficient bridging for controlled shear-thickening. Production pH is maintained at 4.0–5.5 with buffered initiators. Above pH 6.5, alkali hydrolysis of residual acetate groups shifts surface activity and broadens particle size distribution. The grade is suitable for interior and exterior low-VOC paints, nonwoven binders, and construction adhesives where free formaldehyde content must remain below 10 ppm in the wet dispersion.

Why Does S-PVC Suspension Particle Size Distribution Narrow When a Low-Viscosity Partially Hydrolysed PVA Is Introduced as a Secondary Dispersant?

In suspension polyvinyl chloride (S-PVC) autoclaves, primary dispersion is commonly assigned to high-viscosity polyvinyl alcohol grades or cellulose ethers. GOHSENOL NL-05 is metered as a secondary dispersant at 0.02–0.08 wt% on vinyl chloride monomer. The batch is charged with deionised water, monomer, peroxide initiator, and the dispersant package before heat-up to 52–65°C. Reactor pressure is held at 7.0–11.5 bar until the characteristic pressure drop indicates monomer consumption. The addition of NL-05 modifies aqueous-phase interfacial tension during droplet formation and deposits a thin surface coating that regulates PVC grain porosity. Data from 100 mm diameter pilot autoclaves with glass-lined or Pfaudler surfaces indicate that replacing a portion of the primary dispersant with the 5 mPa·s grade shifts median particle size from 150–180 µm to 125–155 µm and narrows the span [(D90−D10)/D50] to below 1.20. Cold plasticizer absorption, tested under ASTM D3367-98, remains within 22–28% when the secondary dispersant ratio is kept below 0.08%. Above this level, residual PVA at the grain surface inhibits free radical ingress, lengthening conversion time by 8–12% and increasing the fraction of glassy particles.

Agitator tip speed must remain below 8.0 m/s. Above this threshold the low-viscosity colloid film tears, primary droplets recoalesce, and the particle size distribution becomes multimodal. Aqueous phase quality is equally critical. Conductivity must be controlled below 5 µS/cm because calcium and magnesium ions crosslink residual acetate groups and generate grain-surface gel skins that slow plasticizer uptake and produce fisheye particles in finished rigid or flexible PVC compounds. Reactor fouling at the condenser surface is monitored by pressure-drop history; a fouling factor above 0.35 m²·K/kW typically requires a 20% reduction in secondary dispersant feed. Published data for NL-05 specifically as a sole primary dispersant in S-PVC is limited; plant-scale use is normally restricted to secondary dispersant or grain-surface modifier roles. This restriction is due to its low molecular weight and lower interfacial film strength compared with fully hydrolysed or higher-viscosity primary grades. For high-K-value resins above K70, the secondary dispersant feed is reduced to 0.02–0.04% to avoid over-stabilisation that delays gelation during processing.

Surface sizing of high-speed inkjet base stock and coated paperboard uses GOHSENOL NL-05 as a co-binder in starch-dominant formulations at 2.0–6.0% solids in a rod-metering size press. The low aqueous viscosity of 4.5–6.5 mPa·s at 4% solids permits operation at 800–1,500 m/min without rod streaking or misting. A typical formulation blends 100 parts oxidised tapioca starch, 25–50 parts NL-05 on dry solids, and 1–3 parts glyoxal or ammonium zirconium carbonate crosslinker. The PVA lowers equilibrium surface tension of the size solution and raises film strength after drying at 110–130°C cylinder surface temperature. IGT pick velocity measured under ISO 3783:2014 improves from a starch-only baseline of 2.2–2.6 m/s to 3.0–3.6 m/s at 5.0% PVA content. In inkjet base stock, the polymer binds silica and precipitated calcium carbonate pigments with specific surface area of 300–600 m²/g, reducing dusting and improving black optical density after dye fixation.

Operational boundaries are narrow. Calcium ions in hard water above 150 ppm as CaCO₃ generate insoluble PVA-calcium complexes that form ridges on the blade and periodic cross-machine coat weight variation. Foam control with non-silicone defoamers is required because NL-05 solutions release air slowly. Entrained air above 3% by volume causes pin holes in the coating layer during metered size press application. Migration into the sheet is influenced by base paper porosity. For high-permeability base sheets with Bendtsen porosity above 2,500 mL/min, size holdout requires raising starch concentration to 8.0% and reducing blade angle to 22–28°. Published data for NL-05 in barrier coating applications is limited; the grade is generally used as a secondary binder rather than as a sole oxygen-barrier layer. Food-contact status is supported under FDA 21 CFR 176.170 and 176.180 for aqueous and fatty food types when the finished paperboard meets extraction limits specified in the regulation.

Textile Warp Sizing and Weaving-Room Performance Limits

On air-jet and high-speed rapier looms operating at 550–800 picks/min, the warp size film must resist repeated abrasion from reed dents and drop wires while remaining completely desizable at finishing. GOHSENOL NL-05 is prepared as a 6.0–10.0 wt% solution in a high-shear jet cooker at 90–95°C and held in the size box at 80–85°C. Size add-on is controlled at 8.0–12.0% on dry yarn weight for rotor-spun cotton and 6.0–9.0% for polyester-cotton blends by adjusting squeeze-roll pressure between 4.0 kN/m and 12.0 kN/m. The low molecular weight of NL-05 allows size box solids to be increased without exceeding 800 mPa·s at 80°C. That viscosity ceiling is critical: above it, size penetration is inadequate and surface layering causes shed-off dust during weaving. Desizing in hot water at 80–90°C for 20–30 minutes followed by alkaline washing removes the film. Incomplete desizing is detectable as fabric stiffening after stentering at 120–130°C.

Weaving room performance data from production air-jet installations indicate warp break rates of 3–6 per 100,000 picks when add-on and drying remain within the specified window. If size box temperature falls below 75°C, NL-05 solutions exhibit surface skinning and roller pick-up becomes uneven because partially hydrolysed PVA has limited re-solubility once a dry film forms. At relative humidity above 65%, sized beams must be wrapped in polyethylene and used within 48 h. Otherwise the film absorbs water, becomes tacky, and adjacent warp ends adhere, causing multiple-end breaks. Waxes or lubricants added above 3.0% on PVA solids reduce film cohesion and increase shed dust without further lowering warp break rate. In blended warps containing starch, the NL-05 fraction should not exceed 35% of total size solids unless the finishing plant operates a strong alkaline desizing stage; otherwise residual PVA can redeposit on the fabric surface and reduce absorbency of bleached finished goods.

Tape casting of alumina and barium titanate substrates for multilayer ceramic capacitors uses polyvinyl alcohol as the primary binder in aqueous slurries. GOHSENOL NL-05 is dissolved at 10.0 wt% in deionised water, then mixed with ceramic powder of median particle size 0.5–1.5 µm, dispersant, plasticiser, and defoamer to form a slip with 65–75 wt% solids loading and Brookfield viscosity of 800–2,000 mPa·s at 25°C by ISO 2555:2018. Binder content is maintained between 5.0% and 10.0 wt% of ceramic dry mass. The low-viscosity PVA grade permits higher solids loading without exceeding practical casting viscosity because its short chain length contributes fewer entangled networks than fully hydrolysed grades. Doctor blade gap is set at 180–300 µm on a heated glass or Mylar carrier, and drying occurs in a multi-zone convection oven from 30°C to 60°C over 12–18 minutes.

During the early drying phase, air velocity above 2.5 m/s can cause surface skinning, trapping moisture and creating lamination voids after isostatic pressing at 30–40 MPa. Green tape tensile strength of 2.5–4.5 MPa with elongation at break 3.0–6.0% is sufficient for punching and screen-printing operations. Binder burnout must be conducted in air with a hold at 350–500°C for 2–4 h. NL-05 leaves residual ash below the 0.5% typical specification when the furnace ramp is controlled at 1.0–2.0°C/min. Faster ramps produce carbonaceous residues that alter dielectric loss tangent in fired ceramic bodies. Incompatibilities include borate ions and divalent cations such as Ca²⁺ at concentrations above 100 ppm, which ionically crosslink the PVA and destabilise the slip. The resulting agglomerates exceed 40 µm after 24 h ageing and cause surface defects in fired tape. Slip pH is maintained at 7.0–8.5 with amine-free bases. Below pH 6.5, dispersant adsorption competes with PVA adsorption and the slip thickens irreversibly.

When Remoistenable Envelope Adhesive Is Formulated for High-Speed Gumming Lines

When remoistenable adhesive for envelope back gum or label paper is formulated, GOHSENOL NL-05 is dissolved at 30–40% solids in water at 80–90°C and plasticised with 2.0–6.0 wt% glycerol or sorbitol on dry polymer. The fluid is coated at 25–60 m/min by reverse gravure or kiss roll at dry coat weight 6–15 g/m². The 86.5–89.0 mol% hydrolysis level and low molecular weight ensure cold-water tack development after rewetting with 10–20 µL/cm² applied moisture. Block resistance of the gummed surface is measured by splicing gum-to-gum and gum-to-paper under 7.0 kPa load at 40°C and 70% RH for 24 h. Release without fibre tear requires plasticiser content below 6.0%; otherwise the film absorbs warehouse humidity and delaminates. Conversely, plasticiser below 2.0% produces film cracking at the crease fold after ageing 30–60 days.

Formulation viscosity is adjusted to 1,500–4,000 mPa·s at 30°C for gravure application. Glyoxal or zinc ammonium carbonate at 0.5–1.5 wt% is added in some formulations to increase wet strength after remoistening and slow complete dissolution to 8–15 seconds under a wetting test. Filler such as lithium bentonite or fumed silica at 0.2–0.8 wt% prevents foaming and pigment settlement. The grade is suitable for indirect food-contact adhesive use under FDA 21 CFR 175.105 when the adhesive is not a functional barrier, and under FDA 21 CFR 176.170 for paperboards in food packaging. An operational constraint appears in high-speed lines above 60 m/min: microfoam entrained during coating collapses after drying to form craters unless a vacuum deaeration step is applied before the coating station. Formulations compounded with borax above 0.1 wt% on dry polymer can form a reversible borate-diol network that raises minimum film-sealing temperature and slows remoistening. Borax is therefore normally avoided for NL-05 remoistenable adhesives.