Polyvinyl Alcohol (PVA, CAS 9002-89-5) is a water-soluble synthetic polymer produced by alcoholysis of polyvinyl acetate. The technical assessment that follows constitutes a PVA Supply to Vietnam & Indonesia: ASEAN Textile Guide for warp sizing, desizing, and incoming-quality control. Commercial textile grades are differentiated by degree of hydrolysis and viscosity of a 4% aqueous solution at 20°C, as measured under JIS K6726 or equivalent supplier methods. Partially hydrolysed grades typically fall within 86.0–89.0 mol% hydrolysis and 4.0–8.0 mPa·s solution viscosity; fully hydrolysed grades usually span 98.0–99.3 mol% and 20.0–30.0 mPa·s. The corresponding degrees of polymerisation are commonly reported as 500–700 and 1700–2200. These parameters govern dissolution temperature, film toughness, size add-on uniformity, and desizing efficiency.

Commercial textile PVA grades are derived from vinyl acetate polymerized in methanol or bulk, followed by alkali-catalysed alcoholysis. Residual vinyl acetate monomer is controlled because it contributes odour and workplace exposure in size-makedown areas. Methanol is an alcoholysis by-product and may remain below 1.0% in dried grades; textile mills with enclosed size kitchens should monitor ventilation according to supplier safety data sheets. Ash content typically remains below 0.5% for low-salt grades; salt content affects solution viscosity and can interfere with conductometric size-box control.

Shipments into Vietnamese and Indonesian ports are generally cleared under HS Code 3905.30. Dry storage should be maintained below 30°C and below 60% relative humidity to limit caking. Incoming lots are typically packed in 25 kg multi-wall bags or 500–1000 kg flexible intermediate bulk containers with a polyethylene barrier layer. Sampling for moisture, particle size, residual vinyl acetate monomer, and viscosity should follow a documented inspection plan, with moisture determination by Karl Fischer titration per ISO 15512:2019. Preferential tariff treatment may be available under the ASEAN Trade in Goods Agreement for originating PVA, but mills should verify the supplier’s Form D certificate against HS Code 3905.30.

Where Does PVA Supply to Vietnam and Indonesia Encounter Textile-Specific Constraints?

Vietnamese and Indonesian textile mills applying PVA on high-speed looms usually operate shuttleless machines with weft insertion rates above 800 weft/min. For spun polyester/cotton counts between Ne 30 and Ne 60, the size add-on is commonly held at 8–12%; excessively high add-on increases hard size that resists desizing, while low add-on raises hairiness and warp stop frequency. Fully hydrolysed PVA is preferred for dense filament polyester and high-twist cotton blends because it forms a stiffer film; partially hydrolysed PVA is preferred where low-temperature desizing is required or where size-room water hardness is high. The table below summarises the usual grade-selection logic for these two market segments.

On multi-cylinder sizing machines with first-can temperatures of 120–140°C and final-can temperatures of 105–115°C, PVA forms a continuous film when size-box solids range from 6.0–10.0 wt%. Over-drying above 160°C can embrittle fully hydrolysed grades; the film elongation at break falls and warp-end shedding increases. Tensile data for free PVA films under ASTM D638-14 generally show ultimate tensile strength of 40–70 MPa for fully hydrolysed PVA and 25–45 MPa for partially hydrolysed PVA, with elongation at break of 80–250% depending on plasticizer content and conditioned relative humidity. These values support high abrasion resistance on warp yarn, but published data for specific Vietnamese ring-spun cotton counts is limited because film properties are strongly affected by yarn surface chemistry and size penetration.

Size-box temperature is normally held at 70–90°C. For fully hydrolysed PVA, cook temperature should reach 90–95°C for 20–30 min under low-shear agitation to prevent fish eyes. Partially hydrolysed PVA can be dispersed at 20–40°C with high-shear agitation at tip speeds below 20 m/s to avoid air entrainment. A processing window of ±5°C in size-box temperature is typical because viscosity shifts above ±0.5 mPa·s outside this band can alter add-on on absorbent cotton blends. The size formulation should avoid borate-based additives. Borate ions crosslink PVA through 1,3-diol units, producing a reversible gel that can raise size-box viscosity and produce uneven film thickness on warp yarn.

When Relative Humidity Exceeds 70% in Vietnamese Sizing Rooms

Moisture uptake in PVA is a direct function of hydroxyl-group density and relative humidity. Published sorption isotherms for PVA films at 25°C indicate equilibrium moisture near 5–7 wt% at 65% RH and 12–15 wt% at 85% RH. Because water acts as a plasticizer, high ambient humidity can soften dried size film, reduce warp-beam stiffness, and increase warp-end breakage in the shed. Mills in Ho Chi Minh City and Jakarta therefore commonly specify sizing-room air at 25±2°C and 60±5% RH; where ambient humidity exceeds 70% RH, pre-drying of PVA powder in dehumidified storage at below 50% RH for 24–48 h is required before weighing and makedown.

Because ISO 62 is unsuitable for a water-soluble polymer, equilibrium moisture is generally measured by chamber gravimetry or in-house sorption balance. Film moisture above 9–10 wt% before beaming is associated with blocking and higher loom stop frequency in high-density polyester warp; this threshold is mill-specific and should be validated on a pilot beam before full production. Conversely, at relative humidity below 40%, fully hydrolysed PVA films lose water and become brittle. Mills running air-conditioned dry rooms in northern Vietnam should avoid over-drying and may add polyethylene glycol or another plasticizer at 0.5–2.0 wt% based on dry PVA.

Viscosity Stability and Desizing Efficiency in Low-Liquor Impregnation

Low-liquor size boxes apply size to warp yarn by immersion and nip; the relevant control parameter is solution viscosity at the trough rather than bath volume alone. At 70–90°C, PVA solutions are subject to shear-induced viscosity reduction and foam entrapment. Automatic refractometers or in-line rotational viscometers maintain target viscosity to ±0.5 mPa·s; excursions above this band can shift add-on by as much as 1–2% on absorbent cotton blends, depending on yarn preparation. Batch-to-batch viscosity variance greater than ±2 mPa·s in a 20–30 mPa·s fully hydrolysed grade changes size-box pickup unless solids are trimmed; makedown tanks should therefore be sized for two-bag batches and viscosity correction with heated water. Size makedown filtration through 100–150 µm screen bags removes gel particles; downstream pressure filters are commonly specified at 80–100 mesh.

Desizing of fully hydrolysed PVA requires hot-water washing at 75–90°C because cold water below 40°C leaves residual film that can interfere with subsequent dyeing. In low-liquor desizing washers, PVA concentration in the wash bath rises rapidly; microfiltration or ultrafiltration recovery can be integrated, and supplier technical bulletins report PVA recoveries of 80–90% from concentrated desize effluent, although published data for specific ASEAN mill configurations is limited. Residual PVA not recovered contributes to COD load in textile wastewater, which is regulated under Vietnamese and Indonesian discharge permits. Strong oxidizing agents such as hypochlorite can cleave the PVA chain and reduce final viscosity; bleaching baths should be segregated from size makedown equipment.

Incoming PVA powder from suppliers serving Ho Chi Minh City and Jakarta typically arrives in 25 kg multi-wall bags with a moisture barrier layer or 500–1000 kg FIBCs. Sampling plans should follow ISO 2859-1:2017; moisture content by Karl Fischer titration per ISO 15512:2019 is preferred because oven drying may not discriminate surface moisture from bound water. A typical certificate of analysis for fully hydrolysed textile grade includes hydrolysis degree 98.0–99.3 mol%, viscosity 20.0–30.0 mPa·s, ash <0.5%, volatile matter <5.0%, and residual vinyl acetate monomer <1.0%. Batches with residual vinyl acetate above the supplier specification require increased ventilation during cooking to keep workplace vinyl acetate below the 10 ppm TWA threshold commonly used in exposure assessment; local Vietnamese and Indonesian occupational-exposure regulations should be checked against the safety data sheet.

Supplier qualification for Vietnamese and Indonesian textile mills should include a trial on at least three production beams to monitor beam hardness, size add-on, and loom stop frequency. If beam hardness measured by the mill’s durometer exceeds the target by more than 10%, the PVA grade or size-box solids should be adjusted rather than increasing post-waxing. The trial should also record the desizing wash temperature required to remove 95% of dry size, verified by gravimetric weight loss or iodine staining.