| HS Code | 195288 |
| Chemical Name | Poly(vinyl alcohol) |
| Cas Registry Number | 9002-89-5 |
| Molecular Formula | (C2H4O)n |
| Appearance | White granular powder |
| Degree Of Hydrolysis | 98.0 - 99.2 mol% |
| Viscosity | 23.0 - 27.0 mPa.s (4% aqueous solution at 20°C) |
| Ph | 5.0 - 7.0 (4% aqueous solution) |
| Ash Content | ≤ 0.5 wt% |
| Volatile Content | ≤ 5.0 wt% |
| Specific Gravity | 1.26 - 1.31 |
| Melting Point | 230°C |
| Glass Transition Temperature | 85°C |
| Solubility | Soluble in hot water |
As an accredited SELVOL Polyvinyl Alcohol 523 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 523 is supplied as a free-flowing white powder in 25 kg multi-wall paper bags with a polyethylene liner. |
| Container Loading (20′ FCL) | SELVOL Polyvinyl Alcohol 523 is loaded into a 20-foot container, palletized bags secured properly for safe transport. |
| Shipping | SELVOL Polyvinyl Alcohol 523 ships as a non-hazardous, water-soluble polymer powder in multiwall paper bags or fiber drums. Protect from moisture, heat, and direct sunlight during transit. Avoid creating airborne dust; keep packaging intact and dry. Standard dry cargo container transport is acceptable. |
| Storage | Store SELVOL Polyvinyl Alcohol 523 in a cool, dry, well-ventilated area, away from heat, open flames, and oxidizing agents. Keep containers tightly closed to prevent moisture pickup, as the product is hygroscopic. Avoid generating dust and protect from physical damage. Use within two years when stored under these conditions. |
| Shelf Life | The shelf life for SELVOL Polyvinyl Alcohol 523 is typically 2 years when stored under recommended conditions. |
In surface sizing of recycled linerboard and folding carton board, Selvol Polyvinyl Alcohol 523 functions as a cold-water-soluble film former that can be metered into an oxidized starch size press formulation without destabilizing the anionic starch at pH 6.0–7.5. The grade has a 4% aqueous solution viscosity of 23–27 mPa·s at 20°C and a hydrolysis range of 87–89 mol%, which permits size circulation stability at low temperature while retaining sufficient film coalescence at the size press. Typical addition is 10–20 parts per 100 parts oxidized starch solids, equivalent to 2–4 wt% of total size circulation solids at 6–9 wt% size press solids. The size press is operated as a film-transfer or rod-metered unit with surface temperatures of 60–80°C, and circulation viscosity is held at 25–50 mPa·s at 60°C to prevent slinging while achieving a dry pickup of 1.5–2.5 g/m². Post-size drying uses cylinder groups staged from 90°C to 120°C, with final moisture targets maintained below 8 wt% to prevent blocking in reels. Compliance is anchored to FDA 21 CFR § 176.170 and FDA 21 CFR § 176.180 for paper components in contact with aqueous and fatty foods, with EU framework compliance under Regulation 1935/2004. Mill acceptance measurements normally reference ISO 535 for Cobb water absorption and ISO 8791-2 for Parker Print Surf roughness. Terminal product types include recycled testliner, white-top kraft backboard, gypsum board face paper, beverage carrier board, and folding carton stock requiring surface holdout without impairing repulpability.
In semi-batch polyvinyl acetate emulsion polymerisation conducted in a jacketed stainless steel reactor fitted with pitched-blade turbine agitation at 150–250 rpm, Selvol Polyvinyl Alcohol 523 must maintain colloidal stability during monomer-starved feed without suppressing primary particle nucleation. The polymer is pre-dissolved at 8–10 wt% in deionized water at 80–85°C, cooled to reactor temperature, and then charged at 5–8 wt% based on vinyl acetate monomer for woodworking adhesives requiring a final viscosity of 8,000–15,000 mPa·s at 25°C. For high-solids packaging adhesives, the protective colloid level rises to 8–12 wt% based on monomer, which increases emulsion viscosity but also raises dried film water sensitivity if combined with insufficient coalescent holdout. Reaction is initiated with a potassium persulfate/sodium metabisulfite redox pair at 68–72°C, and the delayed vinyl acetate feed is maintained over 3–4 h to prevent heat accumulation. A production-scale bottleneck appears when the initiator is injected too rapidly; jacket heat removal should limit the exotherm to 20–30°C above setpoint and the reactor heat-up rate to 0.5°C/min to avoid particle size broadening. Below 3 wt% based on monomer, particle coalescence and wall fouling increase measurably, while above 12 wt% based on monomer, viscosity may exceed the mixing capacity of a turbine impeller and the dried adhesive film becomes excessively hydrophilic. Compliance references include FDA 21 CFR § 175.105 for food-packaging adhesives, FDA 21 CFR § 176.170 where the emulsion is used on food-contact board, EU REACH registration for the polymer substance, and EU Regulation 10/2011 for food-contact film layers where applicable. End-product dispersions feed white woodworking PVA glues, paper lamination adhesives, envelope adhesives, and remoistenable paper coatings.
Size-box formulations for ring-spun cotton and polyester/cotton blends use Selvol Polyvinyl Alcohol 523 where the partial hydrolysis range permits cold-water desizing after weaving without caustic scouring. In a high-pressure sizing machine running at 60–90 m/min, size box solids are held at 8–12 wt%, and the grade constitutes 40–60 wt% of total film former on a dry basis, with the remainder consisting of modified starch and acrylic co-binder. Size box temperature is controlled at 85–90°C, and Brookfield viscosity at 85°C is held at 40–80 mPa·s; squeeze-roll pressure at the nip is set to 12–18 kN/m to achieve yarn add-on of 8–12 wt% for cotton and 6–10 wt% for polyester-rich blends. Drying cylinders are staged from 100°C to 120°C, with the final cylinder not exceeding 130°C to avoid film embrittlement and dusting in the loom shed. A recurring production issue occurs when size return lines cool below 70°C, causing starch retrogradation and viscosity drift; jacketed return-line circulation at 75–80°C is required for stable runnability. Compliance references include OEKO-TEX Standard 100 Annex 4 limits for unfixed auxiliaries, ZDHC MRSL Version 3.1, and EU REACH Annex XVII entry 46a for nonylphenol-free formulations. The terminal fabric types are woven shirting, bottom-weight workwear, bed linen, and denim where low add-on, low shedding, and easy desizing are specified by the weaving mill.
Carton side-seam and tube-winding lines that require open time above 12 minutes at 23°C and 50% RH formulate Selvol Polyvinyl Alcohol 523 at 3–6 wt% of the wet adhesive, with 5–12 wt% plasticizer on PVOH solids and 0.05–0.20 wt% defoamer to control aeration during transfer. The adhesive is compounded in a disperser equipped with a sawtooth blade at 1,200–1,800 rpm; the PVOH solution is added after filler dispersion to avoid shear-thinning a partially hydrated polymer and to prevent air entrapment at the blade tip. Final Brookfield viscosity is adjusted to 3,000–6,000 mPa·s at 25°C with spindle 4 at 12 rpm. Application is by disc roller or stencil wheel at 40–60 g/m² wet coat weight, with set time checked on fresh kraft substrate under controlled humidity because partial hydrolysis grades respond to ambient moisture during open assembly. Compliance is governed by FDA 21 CFR § 175.105 for general converting adhesives and FDA 21 CFR § 176.170 where the finished carton contacts dry or aqueous food; wood-bonding grades are additionally tested against EN 204 D2/D3 classification for interior furniture assembly. Terminal stock formats include spiral-wound paper tubes, cones and cores, corrugated board seam bonding, film-laminated carton side seams, and remoistenable label adhesives.
Cold-water-redispersible film former in gypsum skim coat dry mixes requires an addition ratio of 0.3–1.0 wt% of the dry powder, whereas cementitious patching mortars and tile adhesives consume 0.5–1.5 wt%; above 2.0 wt% in cementitious systems, the polymer film can interfere with early hydration and delay compressive strength development. The dry blend is produced in a horizontal ribbon mixer or plowshare mixer for 5–8 minutes at 20–40 rpm, with Selvol Polyvinyl Alcohol 523 added as a pre-ground powder below 500 μm to prevent agglomeration and to distribute through the mix before water addition. After water is added at 25–35 wt% of dry mix, the material is mixed with a slow-speed paddle at 300–500 rpm for 2–3 minutes, applied by trowel, and allowed to set under normal indoor conditions. Compliance references include EN 13279-1:2008 for gypsum plasters, EN 12004 for cementitious tile adhesives, and GB/T 28627-2012 for wall putty. Terminal product types comprise interior gypsum wall putty, skim coat, cementitious tile adhesive, and patching mortar. Operational boundaries apply during storage: the dry mix should not be held above 40°C or above 60% RH, because partially hydrolyzed PVOH will absorb moisture and reduce powder flow before mixing.
In dry-pressed porcelain and technical ceramic bodies, Selvol Polyvinyl Alcohol 523 is introduced into the ball-milled slip at 0.5–2.0 wt% of dry ceramic solids, normally as a 5–8 wt% aqueous solution added after milling to avoid foam generation in the mill. The slip at 60–65 wt% solids is spray-dried in a co-current dryer with inlet air at 200–240°C and outlet at 80–100°C, producing free-flowing granules with moisture of 4–6 wt% and bulk density of 0.85–1.05 g/cm³. Uniaxial pressing is performed at 30–40 MPa, and green flexural strength is measured by three-point bending; the polymer contributes to 2.5–5.0 MPa green strength in porcelain bodies without creating hard granules that resist compaction. Burnout occurs in the kiln preheating zone between 350°C and 500°C, and the low ash specification of the grade limits residue after binder decomposition. Kiln ventilation must be sized for the decomposition gases released between 350°C and 500°C; insufficient airflow in the preheat section can produce carbon deposition on ware edges. Compliance references include ISO 10545 series for finished ceramic tile properties and EU REACH registration for the binder substance. Terminal product types are porcelain floor tile, technical ceramic insulators, alumina-based wear parts, and dry-pressed sanitaryware bodies. Published data for Selvol 523 specifically in low-pressure injection molding configurations is limited.
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SELVOL Polyvinyl Alcohol 523 is a partially hydrolysed, medium molecular weight polyvinyl alcohol resin supplied by Sekisui Specialty Chemicals America. The grade is specified by a Brookfield rotational viscosity of 23.0–27.0 mPa·s measured on a 4 wt% aqueous solution at 20°C, and by a hydrolysis degree of 87.0–89.0 mol%. Release parameters further include a 4 wt% solution pH of 4.5–6.5, maximum ash of 0.5% as Na₂O, and maximum volatile matter of 5.0%. Unlike fully hydrolysed polyvinyl alcohol grades, the residual acetate content in SELVOL 523 disrupts interchain hydrogen bonding, reducing crystallinity and improving cold-water dispersion while lowering dry-film water resistance. The grade is routinely evaluated in aqueous adhesives, paper surface sizing, emulsion polymerisation, and water-soluble film extrusion where its intermediate molecular weight contributes a balance between solution viscosity and dry-film binding strength.
The table below positions SELVOL 523 among the partially hydrolysed SELVOL grades sharing the same nominal hydrolysis interval of 87.0–89.0 mol%.
| Grade | Viscosity (mPa·s) | Hydrolysis (mol%) | Volatile matter (max %) | Ash (max %) |
|---|---|---|---|---|
| 502 | 3.0–3.7 | 87.0–89.0 | 5.0 | 0.5 |
| 504 | 4.0–5.0 | 87.0–89.0 | 5.0 | 0.5 |
| 508 | 7.0–9.0 | 87.0–89.0 | 5.0 | 0.5 |
| 513 | 12.0–15.0 | 87.0–89.0 | 5.0 | 0.5 |
| 523 | 23.0–27.0 | 87.0–89.0 | 5.0 | 0.5 |
| 540 | 45.0–55.0 | 87.0–89.0 | 5.0 | 0.5 |
Because volatile matter and ash ceilings are uniform across the listed grades, solution viscosity is the principal selection criterion. The viscosity ratio between SELVOL 523 and SELVOL 540 is approximately 0.5, meaning that replacement of 540 with 523 reduces low-shear solution viscosity by roughly half at equal solids. This shift is useful when knife-over-roll or slot-die coaters require lower pan viscosity, but it also lowers wet tack and film toughness. The shorter average chain length of 523 produces less chain entanglement than 540, and the difference becomes measurable in tensile strength and shear resistance of the dried adhesive.
In remoistenable adhesive manufacturing, SELVOL 523 is dissolved in jacketed kettles at 20–35 wt% solids, heated to 85°C under low-shear turbine agitation for 30–45 min until the solution is clear, and then cooled to 20–25°C for viscosity adjustment. On high-speed converting lines running at 150–250 m/min, the viscosity set point is maintained within ±10% using a Norcross or Brookfield in-line viscometer to keep dry coating weight between 3–5 g/m². If the set point drifts above the upper limit, the coater deposits excess adhesive and the paper web may block on the reel; if it drifts below, skip coating reduces remoistening tack. Viscosity measurement for these systems is commonly performed in accordance with ASTM D1084 or ISO 2555.
Borate rheology modifiers are added at 0.5–2.0 wt% on dry polyvinyl alcohol to increase low-shear viscosity and improve open time. The reaction between borate and the 1,2-diol units of polyvinyl alcohol is pH-dependent; at pH above 8.0, gel formation accelerates, and formulations containing more than 3 wt% borate can produce false-body gels at 20°C. Because the gel point is a function of polyvinyl alcohol solids, temperature, and pH, no universal borate limit applies; titration with a Brookfield viscometer is performed to define the onset at which viscosity rises by 10× in 60 s. SELVOL 523, with its intermediate molecular weight, exhibits a lower borate gel point than 502 or 513 but a higher gel point than 540 at equal polyvinyl alcohol solids.
End-use compliance for indirect food contact must be validated on the finished adhesive. Where the formulation is intended for food packaging applications, the converter evaluates the complete mixture against FDA 21 CFR 175.105; for paper and paperboard components, FDA 21 CFR 176.170 may apply. The resin’s controlled ash and volatile matter levels support such evaluation, but the final formulation ingredients determine the compliance status.
When SELVOL 523 is used as a surface sizing binder on a metered size press, the bath is typically composed of 2–5 wt% polyvinyl alcohol solids and held at 55–65°C. Application on a puddle or metered size press at 150–250 m/min transfers 0.5–1.5 g/m² dry polyvinyl alcohol to the sheet. The treated paper is evaluated for Cobb water absorption according to ISO 535, IGT pick strength according to ISO 3783, and tensile properties according to ISO 1924-2. Because SELVOL 523 is partially hydrolysed, the film retains enough water sensitivity to permit repulping; this is a deliberate operational boundary. Fully hydrolysed grades in the same viscosity band would give lower Cobb values but slower cold-water solubility and higher solution make-down temperatures.
In starch/polyvinyl alcohol size blends, SELVOL 523 is added at 0.5–2.0 wt% of total bath solids to increase surface strength without producing excessive viscosity rise. The low-shear viscosity of the blend is measured at 60°C with a Brookfield RVT; the target is typically set below 100 mPa·s to maintain size press runnability. Beyond 2 wt%, the incremental gain in IGT pick strength slows while viscosity rises steeply; the addition window is therefore narrow. This behaviour differs from lower-viscosity SELVOL 513, which can be used at slightly higher addition levels but contributes less film strength per unit added.
In polyvinyl acetate emulsion polymerisation, SELVOL 523 is charged at 2–10 wt% based on monomer as a protective colloid. The polymerisation is typically run at 70–85°C with delayed initiator addition over 4–6 h. The medium molecular weight of 523 produces a shear-stable emulsion with lower viscosity than 540 at the same solids and higher stabilising capacity than 513. The residual acetate content improves adsorption on polyvinyl acetate particle surfaces, contributing to freeze-thaw stability and controlled particle size distribution. Emulsion viscosity at 25°C is measured according to ISO 2555, while particle size is followed by dynamic light scattering or disc centrifugation. In this application, the grade is selected when the final adhesive requires a balance between high solids and flowable viscosity.
SELVOL 523 is melt-processable when compounded with polyol plasticisers such as glycerol or sorbitol at 15–30 wt% of the total compound. The medium molecular weight of 523 provides lower melt viscosity than 540, reducing motor torque and die pressure in twin-screw extrusion, but also reducing bubble stability in blown film. Extruders with 25–30:1 L/D ratio and co-rotating or counter-rotating screws are used with barrel temperatures from 180–205°C and screw speeds of 100–300 rpm. The melt temperature must be kept below 220°C; polyvinyl alcohol begins to decompose above this temperature, releasing acetic acid and producing yellowing and die-lip deposits. The processing window is therefore narrow, and melt temperature is controlled within ±5°C at the die. SELVOL 523 must be pre-dried to below 0.3% moisture before extrusion to prevent steam-induced bubbles and melt fracture. Storage at relative humidity above 60% requires re-drying in a dehumidified hopper at 60–80°C for 2–4 h.
When SELVOL 523 replaces 540 in water-soluble film, the tensile strength of the finished film is lower because the average chain length is shorter. Published data for this specific configuration is limited; the direction of the change is established, but the numerical loss must be determined by line trials using ISO 527-3 for film tensile properties. Incompatibilities include strong acids, which hydrolyse the acetate groups, and high concentrations of borate salts, which crosslink the polyvinyl alcohol and raise melt viscosity or gel the melt. The resin is not suitable for applications requiring long-term water resistance because the 87.0–89.0 mol% hydrolysis leaves the film soluble in cold water.
