| HS Code | 615454 |
| Viscosity 4 Percent Solution 20c | 18-22 mPa·s |
| Degree Of Hydrolysis | 91.0-93.0 mol% |
| Ph 4 Percent Solution | 5.0-7.0 |
| Ash Content Max | 1.2% |
| Volatile Content Max | 5.0% |
| Average Molecular Weight | 130,000 g/mol (approximate) |
| Density Solid | 1.27 g/cm³ (typical) |
| Bulk Density | 0.5-0.7 g/cm³ (typical) |
| Melting Point | 180-190°C |
| Glass Transition Temperature | 85°C |
| Tensile Strength Film | 50 MPa (typical) |
| Elongation At Break Film | 200% (typical) |
| Refractive Index | 1.49 (typical) |
| Solubility In Water | Soluble in hot water (>70°C) |
As an accredited SELVOL Polyvinyl Alcohol 418 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 418 is supplied as a free-flowing powder in 25 kg multi-walled paper bags with a moisture barrier. |
| Container Loading (20′ FCL) | 20′ FCL container loading of SELVOL Polyvinyl Alcohol 418, securely packed on pallets, stabilized and sealed for safe transport. |
| Shipping | SELVOL Polyvinyl Alcohol 418 ships as a non-hazardous, water-soluble powder in sealed multi-wall bags or drums. Protect from moisture, humidity, and direct contact with water. Store in a cool, dry area; avoid extreme heat. Standard dry van transport is suitable; no special dangerous goods declarations required. |
| Storage | Store SELVOL Polyvinyl Alcohol 418 in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep containers tightly sealed to prevent moisture absorption, as the powder is hygroscopic. Avoid dust accumulation and contact with oxidizing agents. Use proper handling to prevent static discharge. |
| Shelf Life | Shelf life is typically 2 years from manufacture when stored sealed, cool, and dry, avoiding moisture and freezing. |
In water-soluble film converting for unit-dose detergents, SELVOL Polyvinyl Alcohol 418 is processed as the primary film former because the 87–89 mol% degree of hydrolysis and 17.0–20.0 mPa·s viscosity, measured as a 4% aqueous solution at 20°C, balance cold-water solubility with adequate mechanical strength for pouch conversion. The dry film compound normally contains 62–80 wt% Selvol 418, glycerol/sorbitol plasticizer at 12–25 phr, nonionic wetting agent at 0.5–3.0 phr, and particulate anti-block at 1.0–4.0 phr; the aqueous dope is prepared at 18–28 wt% solids for slot-die or reverse-roll casting. Where the finished unit-dose product is assessed as a detergent article, compliance is evaluated under the EU Detergent Regulation (EC) No 648/2004 and OECD 301B ready biodegradability; where the film is converted into food-contact packaging, FDA 21 CFR 177.1670 and Commission Regulation (EU) No 10/2011 are applicable, though published migration data for this specific SELVOL 418 film formulation is limited and converter-side testing is required. Production-scale dissolution is run by cold-water slurrying at 10–20°C, controlled heating at 0.5–1.0°C/min to 85°C, and a hold of 30–45 min; deaeration under -0.08 MPa vacuum removes micro-bubbles before the dope enters the die. On stainless-steel belt or chrome drum casters, wet film thickness is held at 600–1,200 µm, and multi-zone drying at 70–100°C reduces residual moisture to 2–5 wt%. A documented line failure is edge thinning and low slitting tear when dope viscosity falls below 8,000 mPa·s at 70°C, typically caused by plasticizer migration or insufficient Selvol 418 solids. Terminal products include laundry unit-dose pods, automatic dishwashing pouches, agrochemical water-soluble sachets, dye and pigment preweighed packs, and cement admixture delivery pouches.
The substitution of oxidized starch with SELVOL Polyvinyl Alcohol 418 in surface size formulations changes the shear-thinning behavior of the circulating size press bath, especially in rod-metering and puddle size press systems. The compliance foundation for food-contact paper and board is FDA 21 CFR 176.170, FDA 21 CFR 176.180, and BfR Recommendation XXXVI for the German and broader EU converter market, with ISO 536 grammage and ISO 535 Cobb tests used after surface application. The addition ratio in surface sizing is normally 1.5–5.0 parts of Selvol 418 per 100 parts of dry fiber, while pigmented coating co-binder use operates at 1.0–4.0 parts per 100 parts of dry pigment; higher loadings increase blade coater high-shear viscosity beyond practical limits at speeds above 1,200 m/min. Downstream processing starts with PVOH slurrying through an eductor, dissolution at 90–95°C, filtration through 100–150 µm bag filters, and circulation to the size press at 55–65°C. The process boundary most often observed at production scale is foam stabilization in the recirculation loop from high-shear pumps and return piping; silicone defoamers reduce foam but can depress ink adhesion, so mineral-oil or fatty-acid defoamers are typically tested first. Terminal product types include inkjet coated paper, release base paper, thermal paper, security paper, and folding boxboard with surface strength requirements above 16 Dennison wax pick values.
In semi-batch vinyl acetate homopolymer and ethylene-vinyl acetate emulsion reactors, SELVOL Polyvinyl Alcohol 418 is charged as an aqueous protective colloid that undergoes partial grafting at vinyl acetate radical sites during polymerization. The addition ratio on total monomer is typically 3.0–8.0 wt%, with the upper portion used for low-to-medium viscosity polyvinyl acetate emulsions and the lower portion preferred for high-solids ethylene-vinyl acetate emulsions at 55–72% solids to prevent coagulum. The aqueous feed solution is prepared at 7–12 wt% solids, with dissolution at 85–90°C and cooling to reactor temperature. Compliance with adhesive and paper end uses is anchored to FDA 21 CFR 175.105, FDA 21 CFR 176.170, and FDA 21 CFR 176.180; the emulsion producer must verify residual vinyl acetate monomer below 0.1 wt% under CLP Regulation (EC) No 1272/2008 for hazard classification. The downstream polymerization process uses a jacketed stainless-steel reactor with a pitched-blade turbine impeller at 60–80 rpm, delayed monomer feed over 180–240 min, and redox initiation maintained at 65–75°C; pH is controlled at 4.0–5.5 with a sodium acetate buffer. A production-scale failure mode is viscosity drift in the Selvol 418 solution when it is held for more than 8 h after dissolution, causing batch-to-batch shifts in final emulsion Brookfield viscosity of ±200–500 mPa·s and requiring tighter feed-tank hold times. Terminal product types include polyvinyl acetate wood adhesives tested to EN 204 durability classes D2 and D3, paper packaging adhesives, laminating adhesives, and formulated construction adhesives.
Remoistenable adhesive converting for water-activated paper tape and envelope front seams operates most predictably when SELVOL Polyvinyl Alcohol 418 is used as the primary film former at 85–95 parts per 100 parts of dry adhesive solids, with polyethylene glycol or glycerin plasticizer at 5–12 phr, dextrin or rosin ester modifier at 0–10 phr, and silicone-free defoamer at 0.05–0.2 phr. The compliance boundary for indirect food-contact adhesives is FDA 21 CFR 175.105, with FDA 21 CFR 176.170 invoked where gummed paper may contact dry or aqueous foodstuffs; EU converters may additionally request BfR Recommendation XXXVI and REACH documentation. Downstream preparation is carried out in a vertical planetary mixer at 25–30% solids by hydrating Selvol 418 in cold water at 10–25°C, heating to 85–88°C at 60 rpm blade speed, and holding for 40 min to eliminate gel particles before the adhesive is screened through 125 µm mesh. The coat weight applied to 35–45 g/m² kraft paper is typically 40–55 g/m² wet, using reverse-roll or slot-die coating and a drying tunnel at 60–90°C until paper moisture reaches 6–9%. A plant-scale failure mode is stringing and edge build-up on gummed tape rewinds when solution viscosity exceeds 4,000 mPa·s at 50°C; this is controlled by lowering preparation solids or increasing plasticizer within the stated range. The raw resin should be stored at RH < 60% and 10–30°C because moisture uptake creates lump formation during slurry feeding and increases bag-filter pressure drop. Terminal products include water-activated gummed paper tape, wallpaper paste pre-coat, water-activated label adhesive, and envelope rear seam gum.
Slasher operations producing cotton and polyester/cotton warp yarns evaluate SELVOL Polyvinyl Alcohol 418 when loom stop rates indicate that surface film strength or abrasion resistance is insufficient. The addition ratio in the total dry size mix is 40–70% Selvol 418, with oxidized starch at 25–45% and polyacrylic acid ester or acrylic size at 3–10%; size box solids are held at 8.0–13.0% for dense shirting and workwear constructions, giving a Zahn cup #3 viscosity of 12–25 s at 85°C. Compliance is assessed under OEKO-TEX Standard 100, ZDHC MRSL v3.0, and REACH; buyer restricted substance lists commonly require absence of alkylphenol ethoxylates and confirmation that desizing effluent does not leave persistent PVOH deposits on fabric. The downstream process uses separate cooking circuits: starch is jet-cooked at 115–125°C and cooled to 90°C, then blended with a Selvol 418 solution prepared at 85°C and filtered through 150 µm mesh before entering the slasher size box. Warp yarn is processed at 40–90 m/min, squeezed through double-roll pressure stations, and dried on cylinder cans with first can surface temperature at 110–130°C before weaving at 500–800 picks/min on air-jet or rapier looms. Production staff report edge flaking and size box skin formation when the PVOH-containing liquor stagnates above 70°C for more than 60 min, especially when process water hardness exceeds 250 ppm CaCO3. Terminal products include cotton shirting, polyester/cotton workwear, denim warp yarns, and bed linen fabrics.
Ceramic tape casting lines that run SELVOL Polyvinyl Alcohol 418 as the primary aqueous binder usually adjust slurry solids around the grade’s 0.5% ash ceiling and 87–89 mol% hydrolysis level, which influence low-temperature dissolution and binder burnout behavior. The addition ratio is 8–15 wt% of dry ceramic powder, supplied as a 10–15 wt% aqueous binder solution, with plasticizer at 10–25 wt% of binder solids, polyacrylate dispersant at 0.5–1.5 wt% of powder, and slurry solids controlled at 55–70 wt%. Regulatory compliance for electronic ceramic substrates commonly references RoHS Directive 2011/65/EU, REACH SVHC communication, and ISO 14644-1 Class 7 cleanroom casting; fired alumina is tested under ASTM C373-18 where water absorption below 0.5% is required for dense substrate grades. The production process uses two-stage ball milling with yttria-stabilized zirconia media for 12–24 h, vacuum de-airing at -0.09 to -0.095 MPa for 20–40 min, and doctor-blade casting on silicone-coated PET carrier at 0.3–2.0 m/min with blade gaps from 100 to 400 µm. Drying is operated at 40–70°C in air-flotation or rack tunnels, and binder burnout is ramped at 0.5–1.0°C/min through 300–500°C before high-temperature densification of alumina at 1,450–1,600°C. A documented boundary is green tape curl at room humidity above RH 55% because SELVOL 418 absorbs moisture from casting-room air, shifting release behavior and final dimensional tolerance. Terminal products include alumina substrates, LTCC green sheets, ceramic sensor substrates, piezoelectric green tape, and porous ceramic filters.
Competitive SELVOL Polyvinyl Alcohol 418 prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615380400285 or mail to sales2@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615380400285
Email: sales2@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
SELVOL Polyvinyl Alcohol 418 is a partially hydrolyzed polyvinyl alcohol resin, CAS 9002-89-5, supplied as white to off-white free-flowing granules. The grade is defined by a 4% aqueous solution viscosity of 18–22 mPa·s at 20 °C and a degree of hydrolysis of 87.0–89.0 mol%. These two parameters place the resin in the intermediate-viscosity segment of the partially hydrolyzed PVOH range, between low-viscosity grades used for high-solids adhesive formulations and higher-viscosity grades used for film and heavy-coating applications. The residual acetate concentration, approximately 11–13 mol%, reduces crystallinity and permits dissolution at lower jacket temperatures than fully hydrolyzed grades. Batch-to-batch viscosity drift in incoming material is a primary control variable on adhesive and coating lines because it directly affects transfer roll pick-up, rod coater wet film thickness, and size-press penetration. In applications where the dried adhesive film must be repulpable or easily removed in cold water, the partially hydrolyzed structure is preferred over fully hydrolyzed alternatives.
The hydrolysis value is the mole percentage of acetate groups converted to hydroxyl groups. At 87–89 mol%, the polymer retains sufficient acetate functionality to disrupt intermolecular hydrogen bonding and reduce crystalline ordering, but not enough to produce a dried film that dissolves instantly in cold water. Aqueous make-down is typically conducted by dispersing the granules at 20–30 °C and then heating to 85–90 °C; fully hydrolyzed grades with hydrolysis above 98 mol% require higher temperatures, commonly 90–95 °C, and longer hold times to reach equivalent solution clarity. This lower dissolution energy reduces steam demand in jacketed make-down tanks and shortens the cycle time in high-volume adhesive plants. In the dried state, the same acetate content increases sensitivity to cold water, which is an advantage in repulpable paper coatings and warp sizing but a limitation in water-resistant packaging films unless a crosslinker is introduced. The mid-range viscosity also controls penetration into porous substrates; at equal solids, a low-viscosity grade will penetrate rapidly, while SELVOL 418 allows a longer open time for fiber wetting without the excessive thickness of a fully hydrolyzed high-viscosity film.
Incoming inspection of SELVOL 418 generally uses the matrix below. Internal QC laboratories may substitute equipment-specific methods only after correlation studies against the listed designations. The 4% solution viscosity is measured after complete dissolution and conditioning at 20 °C; because the solution is slightly shear-thinning, the rotational viscometer spindle and speed must be recorded. Where ASTM D2196-20 is used, the spindle and speed selection is specified; where JIS K6726 is used, the method defines the viscometer and temperature. Volatile content is determined by drying at 105 °C to constant weight and is used to correct gravimetric dosing. Ash content is a trace catalyst residue indicator and influences clarity in thin film applications.
| Parameter | Typical specification | Test designation |
|---|---|---|
| 4% aqueous solution viscosity at 20 °C | 18–22 mPa·s | JIS K6726 |
| Degree of hydrolysis | 87.0–89.0 mol% | JIS K6726 |
| pH | 4.5–6.5 | JIS K6726 |
| Volatile matter | ≤5.0% | JIS K6726 |
| Ash as Na₂O | ≤0.5% | JIS K6726 |
A batch with viscosity near the upper limit will require either reduced solids or higher dilution to maintain the same applicator viscosity. A batch near the lower limit may need slightly higher solids. Such adjustments are routine on production lines, but they must be completed before the addition of borax or thickeners because those additives interact nonlinearly with baseline PVOH viscosity.
Preparing a stock solution at 10–15% solids in a jacketed stainless-steel tank equipped with a turbine impeller and recirculating loop begins with charging cold water at 20–30 °C and adding the granules slowly under agitation. The cold dispersion is allowed to hydrate for 15–20 min before heating to 85–90 °C; the hold time is 30–45 min after the batch reaches temperature. Direct addition to hot water or fast powder addition forms gel-coated lumps that cannot be fully dispersed at typical impeller speeds. A 150 µm basket strainer downstream of the recirculating pump removes agglomerates before use in metering systems. Viscosity checks at production temperature are performed with a Brookfield LVT viscometer at 60 rpm; a shift of more than ±2 mPa·s from the target value is corrected by adjusting non-volatile content, not by increasing shear indefinitely, because prolonged high-shear circulation can reduce final adhesive film strength. In warm climates or during humid seasons, pre-drying of the granules may be unnecessary if storage has been kept below 60% relative humidity; otherwise, moisture gain above 5% volatile content will change the solids calculation and require longer drying in the preparation tank.
The cis-1,3-diol units in PVOH react with borate ions to form reversible diol-borate complexes. In dilute solution, addition of sodium tetraborate decahydrate at 0.1–0.5 wt% of solution mass raises viscosity significantly; at higher addition, the system can form a coherent gel. This sensitivity is used deliberately in starch-free corrugating adhesives and in some gelled PVOH ink carriers, but it must be controlled by metered addition and pH buffering. Because the complex is reversible, a borate-induced gel can be partially reversed by lowering the pH below 7.0, although viscosity recovery is not linear and the final flow curve may remain altered. Cationic wet-strength resins and polyamide-epichlorohydrin additives can form charge-complex precipitates with partially hydrolyzed PVOH; compatibility must be tested at production pH before adding both to a single circulation line. Uncontrolled addition of amine-based additives that raise pH above 9.5 accelerates ester hydrolysis and causes viscosity drift over a running shift, especially in tanks held at elevated temperature for more than 60 min.
The selection between SELVOL 418 and adjacent grades is governed primarily by the relationship between solution viscosity at equal solids and wet film thickness on the applicator. At a given percent solids, a low-viscosity partially hydrolyzed grade generates a thinner wet film and greater substrate penetration; a fully hydrolyzed grade generates higher cold-water resistance after drying but also a higher dissolution temperature. The table below compares representative ranges; exact supplier certificates should be used for batch-specific decisions.
| Grade class | 4% aqueous viscosity at 20 °C | Degree of hydrolysis | Process consequence |
|---|---|---|---|
| Low-viscosity partially hydrolyzed PVOH | 5–6 mPa·s | 87–89 mol% | Higher solids at equal coater viscosity; lower wet film thickness; faster substrate penetration |
| SELVOL Polyvinyl Alcohol 418 | 18–22 mPa·s | 87.0–89.0 mol% | Intermediate wet film thickness; moderate penetration; lower dissolution temperature than fully hydrolyzed resin |
| Fully hydrolyzed PVOH | 25–32 mPa·s | 98.0–99.0 mol% | Higher cold-water resistance after drying; higher dissolution temperature; harder film |
In textile warp sizing on shuttleless looms, the 18–22 mPa·s viscosity provides sufficient film formation on polyester-cotton warp yarn when used at 5–8% non-volatile solids and 70–80 °C in a conventional size box. The partially hydrolyzed structure gives a softer, more flexible warp film than fully hydrolyzed PVOH and is removed more readily in cold-water desizing, which reduces energy in finishing. Draw-off from the size box is controlled by the size-box temperature and the number of squeeze-roll passes; viscosity loss above 90 °C is minimized by holding the size box jacket below 85 °C.
Repulping of corrugated and folding carton stock containing SELVOL 418 is measured by TAPPI T 205 sp-18 or equivalent. The partially hydrolyzed resin disperses in warm water at 45–55 °C within 10–20 min under alkaline pulper conditions, whereas fully hydrolyzed residuals can require higher temperature and longer agitation. This behavior is one practical reason paper converters select the 418 grade for recycle-friendly adhesive and coating formulations.
Plasticized melt processing of SELVOL 418 in a counter-rotating twin-screw extruder with L/D 30:1 and barrel temperature zones from 165 °C to 185 °C requires a plasticizer package such as glycerol, sorbitol, or trimethylolpropane at 15–30 phr. Without plasticizer, the glass transition and degradation onset are close; localized barrel hot spots above 200 °C produce acetaldehyde and acetic acid by-products, yellowing, and crosslinking. The same by-product formation can occur in solution if the hold time exceeds 60 min at 95 °C or if the pH is held above 9.5 for extended periods. Melt processing of this grade is therefore limited to plasticized systems and requires independent degassing ports and low-shear screw elements in the melting zone. Published data for this specific configuration is limited outside supplier technical reports; process start-ups should begin with a 5 °C stepwise temperature reduction and verify volatile content at the die.
Regulatory documentation for food-contact adhesive and paper applications is commonly reviewed against 21 CFR 175.105, 21 CFR 176.170, 21 CFR 176.180, and 21 CFR 177.1670. The grade is not automatically food-contact compliant in every finished article; the converter must verify that the final formulation, migration limits, and conditions of use fall within the applicable citation. Storage conditions for unopened bags are below 30 °C and below 60% relative humidity; open bags should be re-sealed because moisture uptake above 5% volatile content changes the gravimetric solids calculation and can promote caking. The dried polymer is combustible as a dust cloud; normal dust-control measures apply. REACH registration and RoHS status are supplier-level declarations and should be obtained from the certificate of compliance for each lot.
