GOHSENX L-3266

GOHSENX L-3266 is a partially hydrolysed poly(vinyl alcohol) resin supplied for aqueous solution preparation, protective-colloid applications, and binder compounding rather than direct melt processing. The model designation identifies a grade in the intermediate-molecular-weight, low-crystallinity band of PVOH: the 4 % aqueous solution viscosity is typically controlled between 26.0–30.0 mPa·s at 20 °C by JIS K6726, and the degree of hydrolysis is typically held between 86.5–89.0 mol%. Lot-release testing also commonly reports volatile content no greater than 5.0 wt%, ash no greater than 0.5 wt%, and solution pH between 5.0 and 7.0. Table 1 sets out the specification envelope used for incoming inspection and batch-acceptance control.

Differences from fully hydrolysed PVOH grades are concentrated in dissolution behaviour and film mechanics. The residual acetate groups in GOHSENX L-3266 depress crystallinity, which allows dissolution onset in the 20–40 °C range instead of the 70–85 °C range required by grades above 98 mol% hydrolysis. The trade-off is lower moisture resistance in the dried film and higher sensitivity to polyvalent salts. In production-scale make-down tanks, the preferred procedure is cold-water dispersion followed by heating to 80–90 °C under low-shear agitation. Direct addition to water already above 50 °C can create a surface skin that prevents wetting of the remaining granules and produces gel eyes. Stainless steel or glass-lined vessels equipped with axial-flow impellers are suitable; high-speed sawtooth dispersers above 3 m/s tip speed introduce microfoam that persists in the stock solution.

What limits dissolution temperature and viscosity stability in partially hydrolysed PVOH?

For GOHSENX L-3266, the 86.5–89.0 mol% hydrolysis range leaves a distribution of residual acetate groups that disrupt interchain hydrogen bonding. The practical effect is that solution preparation can begin at 20–40 °C, but the exact dissolution rate depends on granule size, agitation time, and water hardness. Hard water with high calcium or magnesium content can reduce the effective solubility window by promoting ionic bridging at the particle surface. Measured under JIS K6726, the 4 % solution viscosity is reproducible only when the dissolution history is fixed; variability in heating rate and hold time can shift the apparent viscosity by more than the nominal lot tolerance.

Stored PVOH solutions are susceptible to biological degradation if no preservative is present. Unpreserved solutions can show measurable viscosity loss within 48–72 h at 25 °C. Production systems that hold stock solutions for more than one shift therefore require antimicrobial preservation and regular viscosity checks using ISO 2555 rotational viscometry. Buffering with sodium acetate/acetic acid is commonly applied to hold pH between 5.0 and 7.0. At pH below 4.0, acid-catalysed hydrolysis of residual acetate groups slowly increases the degree of hydrolysis and can shift solution viscosity upward over storage; at pH above 9.0, saponification accelerates and can produce similar drift. Published data for this specific grade under all storage regimes is limited, so plant trials should include viscosity monitoring at 24 h, 72 h, and 14 days before fixed batch cycles are approved.

Filtration performance also defines the practical working range of the dissolved resin. A 100–200 µm bag filter or in-line strainer removes residual gel specks before coating or polymerisation use. High-viscosity tails caused by undissolved material can be reduced by adding the granular resin through an eductor or high-shear wetting device that disperses individual particles before the temperature is raised.

In emulsion polymerisation of vinyl acetate and copolymer systems, a protective colloid must balance aqueous-phase viscosity build against particle-size regulation. GOHSENX L-3266 is typically prepared as an 8–12 wt% aqueous solution and metered into the initial charge at 2–10 parts per hundred parts monomer, depending on target particle size and reactor fluid mechanics. In semi-batch reactors with pitched-blade impellers and jacket temperatures of 65–80 °C, the PVOH partially grafts onto the latex particle surface. Increasing the L-3266 charge reduces mean particle size while raising final latex viscosity; above approximately 8 phm, the viscosity response becomes disproportionate and bridging flocculation or reactor wall scale can occur.

The hydrolysis band of 86.5–89.0 mol% provides sufficient surface activity to stabilise vinyl acetate and acrylic copolymer dispersions, but the level of blockiness in the residual acetate distribution also affects performance. A blockier distribution produces stronger hydrophobic association with monomer droplets, whereas a random distribution favours solution viscosity control. Batch-to-batch variation in degree of hydrolysis can therefore alter particle-size distribution even when the 4 % viscosity remains within specification. Production lines frequently pre-blend lots to hold a make-down solution viscosity tolerance of ±0.5 mPa·s and use dynamic light scattering or laser diffraction to track changes in D50 during scale-up. Continuous emulsion polymerisation with this grade is less well documented than semi-batch operation; published data for this specific configuration is limited, and pilot trials are required before continuous reactor qualification.

When GOHSENX L-3266 replaces fully hydrolysed grades in water-resistant adhesive compounding

Substitution of a partially hydrolysed PVOH for a fully hydrolysed grade changes the adhesive failure mode from cohesive to substrate-adhesive under wet conditions. The lower crystallinity of GOHSENX L-3266 can maintain dry bond strength, but water resistance at 23 °C immersion or 90 % relative humidity cannot be assumed. Adhesive formulators using this grade in paper and packaging applications should evaluate wet shear strength according to ASTM D905 or equivalent internal methods, not only dry tensile lap-shear values. The dry shear values may be acceptable while wet strength falls below the required specification, particularly when the substrate is absorbent and the bond line is exposed to moisture for more than 24 h.

In polyvinyl acetate-based wood adhesives, GOHSENX L-3266 functions as a rheology modifier and dispersion stabiliser. Loading is commonly 3–8 wt% of total adhesive solids. Plasticisers such as glycerol or sorbitol at 5–15 phr reduce minimum film formation temperature but also increase creep. Without crosslinking, the grade is generally limited to interior or non-structural bonding under classification systems such as EN 204/205; D1 and D2 service conditions are attainable, while D3 or D4 water-resistant service requires a crosslinking mechanism or a co-binder. Glyoxal-based crosslinkers respond less predictably with this partially hydrolysed grade because the lower 1,2-diol content reduces acetal formation compared with fully hydrolysed PVOH. Borax addition can be used to increase cohesive viscosity, but the gelation point is sharp: at 1–2 % borax on PVOH solids, viscosity rises strongly; above approximately 5 %, a gel network forms and the adhesive becomes difficult to spread.

Incompatibilities include polyvalent metal salts. Aluminium sulfate, ferric chloride, or zirconium salts above 0.1 wt% in the formulated adhesive can precipitate the PVOH and produce visible flocculation or viscosity instability. Strong oxidisers, including hypochlorite cleaning residues, can degrade the polymer and lower viscosity. Regulatory status for food-contact adhesives or coatings must be confirmed against the current manufacturer declaration and intended use; PVOH grades may be permitted under frameworks such as FDA 21 CFR 175.105 or EU Regulation 10/2011, but lot composition and residual monomer levels govern the final control.

Paper and textile surface sizing operations expose the same polymer to rapid shear, hydrophobic fibre substrates, and transient pH excursions. Surface size formulations containing GOHSENX L-3266 at 4–8 wt% solids are applied at 40–60 °C on a size press or film press. The resin provides film strength and oil-holdout but remains water-sensitive unless an insolubiliser or co-binder is added. At blade-metering thicknesses below 50 µm, the solution viscosity supports uniform transfer; at higher solids, rod streaking can occur if the solution temperature falls below 35 °C because viscosity rises sharply. Surface strength is typically assessed by IGT pick testing according to ISO 3783, and the contribution of the PVOH fraction to surface pick is largest when the size solution penetrates less than 20 µm into the base sheet.

For textile warp sizing, the grade is cooked with starch or acrylic size at 85–95 °C and maintained at 60–70 °C in the size box. The low ash content reduces abrasive wear on reeds and drop wires, while the granular form permits direct addition to a starch cook-out vessel. Desizing requires amylase for the starch fraction and hot-water treatment for the PVOH fraction. Residual PVOH can be detected by iodine staining to monitor removal on continuous ranges. If the size film is not fully removed, dye penetration and hand feel are impaired, and the fault is sometimes misclassified as a dyeing defect rather than a desizing failure.

Comparative specification data for binder selection

Selection between GOHSENX L-3266, a fully hydrolysed grade, and a low-viscosity partially hydrolysed grade is governed by dissolution temperature, film mechanics, and colloidal activity. Table 2 summarises property contrasts based on published PVOH grade profiles. Published data for this specific configuration in all listed end uses is limited; the table is a formulation screening aid rather than a substitute for experimental verification.

The same nominal degree of hydrolysis does not guarantee identical solubility. The sequence distribution of residual acetate groups, measured by 13C NMR triad analysis, differentiates a blocky grade from a random grade even when both fall within the 86–89 mol% range. GOHSENX L-3266 is generally not interchangeable with low-viscosity partially hydrolysed PVOH in applications where film strength and viscosity build are required, because the lower-molecular-weight product provides less entanglement and lower cohesive strength. Conversely, it is not a direct substitute for fully hydrolysed PVOH where water resistance, solvent resistance, or high crystallinity are critical.

Water-soluble or dispersible film casting from GOHSENX L-3266 uses 15–25 wt% aqueous stock solutions, often plasticised with 10–20 phr of glycerol or sorbitol. Films cast on chrome-plated or PTFE-coated rolls at 60–80 °C surface temperature release after moisture content falls below 8 wt%. The mechanical response is tested under ISO 527-3; tensile strength in the machine direction is generally lower than a fully hydrolysed film of equivalent degree of polymerisation but elongation at break is higher because residual acetate groups increase free volume. Dissolution time in water at 25 °C is routinely below 60 s for 30 µm film thickness without an insolubiliser. Adding borax or zirconium salts induces gelation and can extend disintegration time. Because borate crosslinking is reversible but strongly pH-dependent, the process window narrows to pH 7.0–8.5 when controlled solubility is required. Storage at relative humidity above 60 % can produce film tackiness and blocking, so closed packaging and pre-drying are required before converting.