Shuangxin 17-99 PVA (PVA 100-27)

Shuangxin 17-99 PVA (PVA 100-27) is a fully hydrolysed polyvinyl alcohol with a 4% aqueous solution viscosity of 25-31 mPa·s at 20°C and a hydrolysis degree of 99.0-100.0 mol%. The nominal degree of polymerization of 1700 places the grade between low-viscosity 17-88 and higher-viscosity 20-99, making it suitable for applications requiring high film strength, organic solvent resistance, and controlled solution rheology. The six downstream routes covered below are limited to sectors where 17-99 is actually consumed: warp sizing, paper surface sizing, polyvinyl butyral precursor synthesis, suspension PVC primary dispersion, cementitious dry-mix modification, and paper tube winding adhesives.

Slasher Sizing of 65/35 Polyester-Cotton Warp Yarns on High-Speed Air-Jet Looms

At a size solids of 10-12 wt%, the 25-31 mPa·s viscosity of 17-99 forms a size film with high abrasion resistance on 65/35 polyester-cotton warp yarn and 100% cotton high-count poplin. Compliance references for the sized fabric before finishing include ISO 13934-1:2013 for widthwise tensile strength retention after desizing, ASTM D2256/D2256M-10(2021) for single-end yarn tensile loss, and OEKO-TEX Standard 100 Annex 6 limits for extractable residues where the finished fabric enters apparel; the desizing overflow is separately monitored for soluble COD because fully hydrolysed PVA is not removed by amylase desizing and requires an oxidative or hot-water wash stage.

Typical size formulation on a double-size-box slasher uses 70-100 parts 17-99 dry solids in the synthetic size component, with the balance an acrylic size or low-viscosity starch, and total liquor solids between 10% and 14%. Dry pick-up is maintained at 9-12% by oven-dry fabric weight for air-jet weft insertion; below 8% loom stops from warp breakage increase, while above 13% shed accumulates on the reed and drop wires. Field reports from slasher operators on double-box slashers indicate that split-rod wear increases once dry pick-up exceeds 13% because the hard film flakes at the splitting zone rather than flexing with the yarn sheet.

Dissolution is carried out in a jet cooker or jacketed mixing tank: 17-99 powder is first dispersed in cold water under agitation, heated to 95-98°C, and held for 45-60 min until the solution clears. The size box is held at 85-90°C, and slasher speed on a two-trough size box with double squeeze rolls is kept between 45 m/min and 70 m/min depending on yarn count and style. Multi-cylinder drying is set to 120-130°C surface temperature, leaving 2-4% residual moisture before the lease rods. The dried warp is not rewound at residual moisture above 4% because moisture plasticizes the film and increases cylinder can build-up. Terminal products include polyester-cotton uniform fabrics, high-count shirting, workwear, and bedsheet quality woven cloth.

What Changes When 17-99 Replaces Oxidized Starch at the Film Press?

Film press runnability with 17-99 depends on the lower dry solids required to reach a target surface strength. In fine paper and release liner base, 17-99 is applied at 0.8-2.0 wt% dry based on final sheet weight, typically as a blend with oxidized starch at a PVA:starch ratio of 1:3 to 1:5. Size press solids of 6-10% produce a metering film with viscosity 30-70 mPa·s at 50°C, low enough for rod-metered or blade-metered film presses. Compliance is evaluated with ISO 535:2014 for Cobb 60 s water absorption, ISO 8791-2:2013 for Parker PrintSurf roughness, and ISO 2470-1:2016 for ISO brightness; food-contact migration is assessed under FDA 21 CFR 176.170 when the finished grade is specified for dry food packaging.

Application at the film press runs at 900-1200 m/min on woodfree paper machines; the film is transferred from the rolls and dried in the after-dryer section to 4-6% sheet moisture. A key process conflict is the hygrosensitivity of fully hydrolysed PVA: at sheet moisture above 6%, calender pickup increases blackening and fiber pick; above 2.0% dry pick-up, the sheet may become dimensionally unstable in high-humidity converting halls. Borated starch or high-pH internal sizing agents should not be mixed with 17-99 in the same size press circuit because borate crosslinking can produce insoluble gel deposits on the metering rod. Finished grades include copy paper, inkjet paper, envelope paper, and base paper for silicone-coated release liners.

In polyvinyl butyral resin synthesis, 17-99 functions as the polyvinyl alcohol backbone rather than a formulation additive. The 25-31 mPa·s viscosity of the 4% aqueous solution transfers into a PVB resin with intermediate solution viscosity, which is preferred for plasticized interlayer film because it combines low gel particle formation during acetalization with sufficient tensile strength after plasticization. Compliance for the final laminated glass interlayer is governed by ISO 12543-2:2011 and ECE R43 for glazing performance, while mechanical properties of the PVB sheet are tested under ASTM D638-14 tensile and ASTM D1003 haze; residual free PVA and acetal levels are tracked in-process because they affect adhesion to glass and moisture pick-up.

The stoichiometric window for 17-99 is controlled by butyraldehyde feed at 0.60-0.75 kg per 1.0 kg dry PVA solids to target an acetalization degree of 76-80 mol% and a residual hydroxyl content suitable for glass adhesion. The aqueous PVA solution is prepared at 7-10% solids, acidified with hydrochloric acid to pH 1.0-2.0, and reacted with butyraldehyde at 85-95°C for 4-8 h; temperature excursions greater than ±2°C during butyraldehyde feed can shift the acetalization distribution and raise gel particle count. The precipitated resin is washed with demineralised water until filtrate conductivity is below 30 µS/cm to limit residual chloride, then dried at 60-70°C under negative pressure. In-process control includes melt flow rate measured under ISO 1133-1:2022 and solution viscosity of a 10% ethanol-toluene solution, which is tightly correlated to the 17-99 feedstock viscosity; batch-to-batch shifts in PVA solution viscosity must remain within ±1 mPa·s.

Terminal products produced from this precursor include plasticized PVB film for automotive windshields, architectural laminated safety glass, and photovoltaic encapsulation interlayers. The fully hydrolysed 17-99 grade is not used directly as the film; it is consumed as an intermediate, so final compliance assessment occurs on plasticized PVB sheet rather than on the PVA powder itself.

When Suspension PVC K-Value and Plasticizer Uptake Must Not Drift

Suspension PVC reactors operating at 105 m³ jacketed capacity use 17-99 as the primary dispersant for vinyl chloride monomer droplets. The addition window is 0.08-0.15 wt% of VCM, combined with a secondary dispersant such as a lower-hydrolysis PVA grade or hydroxypropyl methylcellulose at 0.02-0.05 wt%, giving a total dispersant charge of 0.10-0.18 wt%. This fully hydrolysed grade produces a coarser primary droplet population that resists coalescence during the pressure-rise phase but yields a denser particle skin; when used alone, the resulting PVC grain has lower plasticizer uptake than a dual-dispersant system. The combination of 17-99 with a partially hydrolysed 17-88 grade creates a bimodal droplet size distribution and stabilizes porosity during the critical 30-40% monomer conversion stage when droplet identity is lost.

Polymerization is run at 55-65°C with stirring at 110-140 rpm depending on reactor diameter and impeller type, and the water:VCM mass ratio is kept at 1.05:1 to 1.20:1. Typical reaction pressure for 57°C operation is 0.80-0.90 MPa, and the batch is terminated at 85-92% conversion. After blowdown, unreacted monomer is recovered, and slurry is passed through a stripper to reduce residual VCM below 1 mg/kg under EU 10/2011, with food-contact resin status under FDA 21 CFR 177.195. Resin quality is measured by ISO 1628-2 K-value and plasticizer uptake is measured by ISO 4608; a K-value drift of more than ±1 unit within a lot is typically traceable to dispersant concentration or reactor temperature, not to intermediate PVA viscosity variation. Because 17-99 is fully hydrolysed, it has limited water solubility at low temperature and must be dissolved at 90-95°C before charging to the reactor; incomplete dissolution leads to gel particles that deposit on reactor walls and impeller blades, accelerating polymer scale formation and reducing heat transfer coefficient. Terminal products include rigid PVC pipe, window profiles, cable insulation, and calendered sheet; the grain morphology controlled by 17-99 influences gelation rate in counter-rotating twin-screw extruders with L/D 25:1 to 32:1 and final profile gloss.

The water-retention mechanism of fully hydrolysed polyvinyl alcohol in cementitious tile adhesives is controlled by polymer film formation in the pores of the set mortar rather than by simple thickening. In a C2E tile adhesive, 17-99 is dry-blended at 0.2-0.6 wt% of the total dry mix, with redispersible polymer powder at 1.5-4.0 wt% and cellulose ether at 0.3-0.6 wt%. The PVA addition extends open time and improves adhesion when the mixed mortar is exposed to air movement at 23°C/50% RH by retaining water in the interface layer between tile and bed. Compliance is assessed under EN 12004-2:2017 for C2E classification and EN 1348 for initial tensile adhesion strength; installations in North America are often evaluated under ASTM C627 for floor service conditions.

Production is a dry-mix operation rather than a wet process. 17-99 powder is first premixed with fine calcium carbonate or silica filler at 500-1000 rpm in a high-speed mixer to reduce agglomeration, then transferred to a ribbon blender with cement, sand, and redispersible polymer powder. On the jobsite, the mortar is mixed with 20-25% water by total dry weight and applied with a notched trowel. A process-limiting boundary is the dosage ceiling: 17-99 at or above 0.8 wt% in a CEM I 42.5 R mortar has been observed to extend setting time and reduce 28-day compressive strength, so full-specification formulations keep the PVA fraction below 0.6 wt%. Published data for this exact grade in CEM I 42.5 R tile adhesives is limited, so site validation with the specific cement and sand grading remains required before final dosing. The powder must be stored below 60% RH; moisture ingress creates lumps that do not redisperse in a standard paddle mixer and appear as surface defects after troweling.

Terminal products include C2E ceramic tile adhesives, self-leveling underlayments, and polymer-modified repair mortars.

Paper Tube Winding Adhesives and the Problem of Summer Flow

Summer flow failures in paper tube winding adhesives are most often traced to inadequate high-temperature viscosity from dextrin-only formulations. 17-99 is added at 4-10% of finished adhesive solids, usually with white dextrin at a PVA:dextrin ratio of 1:4 to 1:8 and total solids of 28-35%. The adhesive is prepared in a jacketed high-shear mixer at 60-70°C, then cooled to 35-40°C for application on spiral tube winders running 20-40 m/min. The PVA component increases tack and green strength, but borax must be controlled because high-pH borate addition can cause skinning in the application pan. Compliance for food-contact packaging tubes is evaluated under FDA 21 CFR 175.105 adhesives. Terminal products are spiral paper cores, composite cans, and angle boards.