| HS Code | 975927 |
| Product Name | ELVANOL 50-42 |
| Chemical Name | Polyvinyl Alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White granular powder |
| Viscosity 4 Solution At 20 C | 42 mPa·s |
| Hydrolysis Degree | 98.5% |
| Ph 4 Aqueous Solution | 4.5-6.5 |
| Melting Point | 230°C |
| Glass Transition Temperature | 85°C |
| Specific Gravity | 1.27-1.31 |
| Solubility | Soluble in water; insoluble in organic solvents |
| Moisture Content | ≤ 5% |
| Ash Content | ≤ 0.7% |
As an accredited ELVANOL 50-42 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | ELVANOL 50-42 is packaged in 25 kg multi-wall paper bags with an inner polyethylene liner for moisture protection. |
| Container Loading (20′ FCL) | ELVANOL 50-42 polyvinyl alcohol resin, packed in 20′ FCL, secured and braced for safe, stable transport. |
| Shipping | ELVANOL 50-42 (polyvinyl alcohol) ships as a non-hazardous, water-soluble powder. It is not regulated as dangerous goods under IATA, IMDG, or ADR. Pack in sealed multi-ply bags or fiber drums on pallets; keep dry and minimize dust exposure. No UN number or hazard class required. |
| Storage | Store ELVANOL 50-42 in a cool, dry, well-ventilated area away from heat, ignition sources, and direct sunlight. Keep containers tightly closed to prevent moisture absorption and contamination. Avoid generating dust; protect from physical damage. Store away from oxidizing agents and incompatible materials. Use appropriate personal protective equipment when handling. Ensure proper labeling and access to safety data sheets. |
| Shelf Life | Shelf life is 2 years from manufacture when stored in original, unopened containers in cool, dry conditions. |
In semi-batch manufacture of polyvinyl acetate homopolymer emulsions for wood-assembly adhesives, ELVANOL 50-42 is loaded into the aqueous phase as the primary protective colloid at 2.5–4.5 parts per hundred vinyl acetate monomer. The grade carries a hydrolysis range of 87–89 mol% and a 4 wt% aqueous solution viscosity of 4.0–6.0 mPa·s at 20°C per the Kuraray technical data sheet. The precharge is heated to 68–72°C in a jacketed glass-lined reactor, and 0.15–0.30 wt% potassium persulfate initiator is fed over 3–4 h concurrently with vinyl acetate monomer under a 0.3–0.5 volume-exchange-per-hour nitrogen sweep. A split colloid feed of 70% in the kettle and 30% delayed after 50% monomer conversion limits grafting onto the partially hydrolyzed backbone to approximately 25–35%; exceeding this window produces shear-sensitive latex that can rise above 80,000 mPa·s on a Brookfield RVT spindle 6 at 10 rpm and indicates poor heat transfer on the reactor wall. After monomer feed, a redox hold with 0.03–0.08 wt% tert-butyl hydroperoxide and sodium metabisulfite reduces residual vinyl acetate to below 0.5 wt%. The resulting dispersion is compounded with 5–12 wt% triacetin or dipropylene glycol dibenzoate for fibreboard assembly, and the dry film classification follows EN 204 D2 provided that the bond line is not exposed to sustained water immersion. Food-packaging laminating formulations are used under 21 CFR 175.105 when the adhesive is separated from food by a functional barrier or applied as a dry-bond laminating layer.
Remoistenable seams for envelopes and roll-stock label papers are coated with an 8–12 wt% aqueous solution of ELVANOL 50-42 plasticized with glycerol or PEG 400 at 10–20 wt% on dry PVOH. Reverse roll coating applies a dry add-on of 3–6 g/m² onto bond paper that has been pre-treated with a starch-based holdout layer. The principal failure mode is not solution viscosity—typically maintained below 2,500 mPa·s at 25°C on a Brookfield LV spindle 2 at 30 rpm—but blocking under humid storage, which is evaluated in stacked sheets at 35°C/60% RH. The cooking sequence therefore holds the solution at 88–92°C for 30–40 min, cools to 50°C, and incorporates 0.1–0.2 wt% potassium sorbate and 0.05 wt% sodium benzoate to limit bacterial hydrolysis of acetate groups. Rewet activation on high-speed inserters is adjusted for 3–6 s tack at 8–12 g/m² water surface uptake, and open time is extended above 8 s with 2 wt% propylene glycol. Coated stock intended for indirect food contact is evaluated under 21 CFR 176.170; the dry adhesive layer is not intended for direct fatty or aqueous food contact without a barrier. Published data for high-speed envelope converting speeds above 1,200 envelopes/min with ELVANOL 50-42 is limited.
For spiral and convolute paper tube winders, ELVANOL 50-42 is cooked to 12–16 wt% solids and delivered to a heated glue pan maintained at 60–65°C. At 14 wt% solids, the working viscosity is typically 1,500–3,500 mPa·s on a Brookfield LV spindle 3 at 30 rpm; the acceptable upper limit is set by the grooved steel applicator roll speed and the burst-strength target for the finished tube. Adhesive is transferred at 20–40 g/m² dry add-on to kraft plies with basis weights of 120–250 g/m², and the 3-ply tube is wound under nip pressure of 3–5 bar. Circulating lines are filtered through 150-µm screens and the pH is held at 5.0–6.0; extended shear from mono pumps above 1,000 rpm can foam the solution and reduce transfer uniformity on the applicator roll. Urea is added at 5–10 wt% on PVOH solids for cold-weather open time, while borax is limited to 0.05 wt% because residual 1,3-diol units crosslink and produce a nonlinear viscosity rise that can blind filters. The finished tube stock is tested per TAPPI T 403 for burst strength and conditioned at 40°C/50% RH for 30–60 min before ply-adhesion checks. Food-contact tube winding for dry and non-fatty aqueous products is covered by 21 CFR 176.170 and 21 CFR 176.180; the end-use extraction test obligation remains with the converter.
| Application segment | Regulatory reference | Converter verification requirement |
|---|---|---|
| Adhesive for food-packaging lamination | 21 CFR 175.105 | Functional barrier or dry-bond layer separation |
| Remoistenable envelope coating | 21 CFR 176.170 | Indirect food contact; end-use extraction testing |
| Paper tube winding | 21 CFR 176.180 | Dry and non-fatty aqueous foods; migration testing by converter |
| Textile warp size | REACH Regulation (EC) No 1907/2006 | No SVHC content; desize effluent under EU IED BAT |
High-speed air-jet and rapier looms weaving spun polyester/cotton and polyester/viscose warps in the 20–40 Ne count range require a warp size bath in which ELVANOL 50-42 is combined with thin-boiling corn starch at a dry ratio of 15:85 to 25:75. The size-box solids are controlled at 7–9 wt% and the bath temperature at 78–84°C; wet pickup is set by a squeezing roller nip at 8–15 kN/m to leave 8–12% size add-on on dry yarn. Conditioned film from this formulation at 65% RH shows tensile elongation of 60–120% under ASTM D882-12, which reduces shedding fractures at the beat-up zone. The size supply loop is jacketed and recirculated at 15–25 L/min, and 0.05–0.15 g/L of polysiloxane defoamer is metered into the suction side of the circulation pump to keep warp-sheet foam below visible film defect levels. Desizing uses 0.5–1.0 g/L bacterial amylase at 60–80°C followed by a 90°C overflow wash; residual PVOH can be detected by the qualitative iodine-borax spot test on the greige. Wastewater COD from the size recipe is typically 80,000–120,000 mg/kg dry size, and discharge compliance is managed under the textile finishing BAT reference document of the EU Industrial Emissions Directive. For export fabrics under REACH, ELVANOL 50-42 is registered and does not contribute to SVHC content.
In dry-pressed porcelain stoneware and alumina tile bodies, ELVANOL 50-42 is delivered to the spray-dried slip as a 4–6 wt% aqueous solution and represents 0.5–2.5 wt% dry polymer on total body. The grade is selected where the supplier-limited ash content of ≤0.5 wt% as sodium oxide is acceptable for the fired glaze and engobe contact layer. The binder migrates to intergranular necks during droplet evaporation and increases dried green strength from approximately 1.5–2.5 MPa to 3.5–5.0 MPa measured on 100 × 20 × 5 mm bars by ASTM C674-13. Firing schedules for 600 × 600 × 10 mm tile impose a preheating ramp of 3–5°C/min between 250°C and 450°C to maintain oxidative binder burnout; a 20–30 min soak at 400°C prevents black-core defects in bodies containing up to 0.5 wt% iron oxide. The water-soluble polymer also lowers viscosity in 45–50% solids slips, permitting atomizer nozzle pressure below 25 bar and reducing pump cavitation in the spray-drying feed line. Published data for low-temperature co-fired ceramic tape using ELVANOL 50-42 rather than fully hydrolyzed PVOH or polyvinyl butyral is limited; tape-casting applications generally require higher molecular weight or fully hydrolyzed grades for green film toughness.
For microporous polymer-coated inkjet media, ELVANOL 50-42 is evaluated as a co-binder in fumed silica dispersions where the binder-to-pigment ratio is maintained at 15:100 to 25:100 dry weight. The silica slurry is dispersed at 2,000–3,000 rpm with a cowles-type dissolver until the dispersed viscosity falls below 250 cP at 20°C on a Brookfield LV spindle 2 at 60 rpm. The 4 wt% solution viscosity of 4.0–6.0 mPa·s permits binder addition without exceeding the target dispersion viscosity; the residual acetate content reduces interparticle flocculation compared with fully hydrolyzed PVOH, as measured by the same Brookfield method. However, water fastness of the printed dye is limited unless a cationic fixative or silica-alumina sol is incorporated. Coating is applied by slot die at 10–20 µm wet thickness and dried in a post-air-float dryer at 80–100°C to a moisture content of 2–4%. Curl control at 50–60% RH is adjusted with 5–15 wt% sorbitan-based plasticizer on dry binder; excessive plasticizer above 20% re-wets the microporous layer and reduces ink penetration time below 30 s. The coated media are tested for colour density, bleed, and light fastness under ISO 18909. Compliance for non-food paper and film applications is governed by REACH and the Nordic Swan or Blue Angel criteria where applicable.
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ELVANOL 50-42 is a partially hydrolyzed polyvinyl alcohol resin supplied as a white to cream granular powder. The grade designation belongs to the Elvanol portfolio and identifies a low-viscosity polymer with a nominal 4% aqueous solution viscosity of 5.0–6.0 mPa·s at 20 °C and a degree of hydrolysis of 87.0–89.0 mol%. The residual acetate functionality is not a contaminant; it is a compositional variable that controls cold-water solubility, film flexibility, and interaction with cellulosic and inorganic substrates. Because the grade is partially hydrolyzed, the dry-state crystallinity is lower than that of fully hydrolyzed polyvinyl alcohol, which reduces the energy required for dissolution and changes the film’s water sensitivity after drying.
In the Elvanol grade system, the first two digits are commonly associated with the nominal solution viscosity band, while the final digits denote the degree of hydrolysis. For 50-42, the 5 prefix places the product in the low-viscosity range, and the 42 suffix denotes a partially hydrolyzed species. Published quality-control data list the 4% aqueous solution viscosity at 5.0–6.0 mPa·s using Brookfield LVF spindle geometries per JIS K6726; the hydrolysis range is 87.0–89.0 mol%, determined by saponification value or equivalent method. The pH of a 4% aqueous solution is typically 4.5–6.5; volatile matter is controlled to a maximum of 5.0%, and sulfated ash to a maximum of 0.5%. Because the polymer is partially hydrolyzed, it retains hydrophobic acetate groups that reduce hydrogen-bonding density relative to fully hydrolyzed grades. This compositional difference is the primary driver of its cold-water solubility and lower aqueous solution viscosity at equivalent molecular weight.
| Parameter | Test method | Specification or range |
|---|---|---|
| Appearance | Visual inspection | White to cream granular powder |
| Volatile matter | JIS K6726 | ≤ 5.0% |
| Sulfated ash | JIS K6726 | ≤ 0.5% |
| pH, 4% aqueous solution | JIS K6726 | 4.5–6.5 |
| Viscosity, 4% aqueous solution, 20 °C | JIS K6726, Brookfield LVF | 5.0–6.0 mPa·s |
| Degree of hydrolysis | JIS K6726 | 87.0–89.0 mol% |
Partially hydrolyzed PVOH of this viscosity band is selected when the processing sequence requires dissolution at ambient or near-ambient temperatures. Fully hydrolyzed grades with hydrolysis above 98 mol% typically demand heating to 80–85 °C for complete dissolution, whereas 50-42 disperses in water at 20–25 °C and forms clear solutions without a high-temperature hold, provided the powder is added to a well-formed vortex. The trade-off is film water resistance: fully hydrolyzed grades produce dried films with lower cold-water sensitivity and higher tensile strength per ASTM D882, while 50-42 yields films that remain redispersible until insolubilized with glyoxal, zirconium salts, or formaldehyde-free crosslinkers. Compared with higher-viscosity partially hydrolyzed grades of equivalent hydrolysis, the 5.0–6.0 mPa·s solution viscosity of 50-42 permits higher solids loading in size-press and coating formulations before the viscosity exceeds the transfer limits of metering equipment.
When intermediate water resistance is required, 50-42 is blended with fully hydrolyzed PVOH. Blends in the range of 70:30 to 30:70 by weight shift film redispersibility and block resistance. The exact ratio is determined by the required water absorption value and the specific substrate. Such blends are prepared as separate solutions and combined after dissolution to avoid competition for water during hydration.
On production lines equipped with high-shear dispersers or turbine agitators, the resin should be added slowly to the vortex of cold water. If the powder is dumped into stagnant water, partially hydrated skins form that shield the core from further hydration, producing fisheyes that persist through a 200–400 µm filter screen. A typical make-down sequence uses a 1.5–2.5 wt% initial slurry in cold water, followed by in-line heating to 40–50 °C for 20–30 min under agitation. The solution remains stable for several weeks if biocide is present; unpreserved solutions at 20–25 °C can develop microbial growth within 48–72 h. Recirculation through a 100 µm in-line filter removes residual gels before coating or adhesive use.
Rheological evaluation of a 4% aqueous solution with a Brookfield LVF spindle at 60 rpm shows a nearly Newtonian plateau at shear rates below 100 s⁻¹. The viscosity decreases as temperature increases, following typical Arrhenius behavior for PVOH solutions; no anomalous gelation occurs below 40 °C in the absence of borate ions or polyvalent salts. Holding the solution above 60 °C for extended periods can accelerate ester hydrolysis and pH drift, particularly if alkaline additives are present. The addition of borax at 0.1–0.5 wt% on resin solids increases viscosity through reversible diol complexation; measurable gel formation occurs at higher concentrations and pH above 9.0.
Adhesive compounding with 50-42 frequently proceeds through a high-shear Cowles blade or rotor-stator mixer. Formulations for remoistenable envelope adhesives and tube winding typically combine 10–20 wt% PVOH with plasticizers, defoamers, and preservatives. The low solution viscosity reduces air entrainment during mixing at 1000–1500 rpm, but vacuum deaeration is still required for thick films. Borate addition follows the same rheological limits described for aqueous blends; excess borax above roughly 1.0 wt% can cause irreversible gelation or pH drift above 9.0. The residual acetate groups moderate the crosslink density of borate networks, making 50-42 less prone to abrupt gelation than fully hydrolyzed grades.
In vinyl acetate and vinyl acetate-ethylene emulsion polymerization, partially hydrolyzed PVOH functions as a protective colloid and particle stabilizer. The 87.0–89.0 mol% hydrolysis range provides sufficient grafting through residual acetate groups while retaining aqueous solubility. Reactor charging of 2–6 wt% PVOH on total monomer is typical; the low solution viscosity of 50-42 permits high-shear circulation without overloading the reactor agitator. Emulsion viscosity, particle size distribution, and coagulum content are monitored via ISO 2555 or Brookfield methods and laser diffraction per ISO 13320. Compared with higher-viscosity protective colloids, 50-42 produces emulsions with lower final viscosity and smaller mean particle diameters under identical agitation, but published data for this specific configuration is limited. Mechanical stability can be reduced when the PVOH concentration is below 1.5 wt%.
Batch temperature is maintained at 60–80 °C with a reflux condenser, and initiator feeds are adjusted to maintain a starved monomer condition. The grafted PVOH layer contributes to steric stabilization; particle size is typically measured by dynamic light scattering per ISO 22412. If coagulum exceeds 0.1% on total latex, the PVOH addition point is moved from the initial reactor charge to a delayed feed.
In paper surface sizing, the product is applied at 2–8 wt% solids on a metering size press or conventional size press. The low-viscosity profile allows rod-metered transfer at speeds above 800 m/min without excessive misting. The partially hydrolyzed polymer penetrates the sheet to 10–40 µm depending on internal sizing and base-sheet porosity, increasing IGT surface strength and reducing dusting. Sizing efficiency can be measured by TAPPI T 530 size test or Cobb water absorption per TAPPI T 441; the expected Cobb values are formulation-dependent and are not specified by the resin manufacturer. Insolubilization with 0.5–1.5 wt% glyoxal on resin solids or zirconium ammonium carbonate shifts the dried film from water-sensitive to water-resistant.
Pigmented paper coatings employing 50-42 as co-binder are formulated at 0.5–3.0 parts PVOH per 100 parts pigment. The addition contributes to high-shear viscosity and water retention, measured by TAPPI T 701 water retention meter. Because the grade is low-viscosity, the impact on low-shear Brookfield viscosity is smaller than that of high-molecular-weight grades, allowing higher solids coatings to be run on blade coaters.
In textile warp sizing, the grade is combined with starch or modified starch at 60–80 °C in jet cookers or open kiers. The PVOH fraction improves abrasion resistance of sized yarns as measured by loom stop count and yarn hairiness tests, but published data for this specific configuration is limited. Desizing is achieved by washing in hot water at 70–90 °C, because the partially hydrolyzed film does not require oxidative desizing chemistry. The residual acetate groups reduce film brittleness at low loom-humidity conditions, which lowers end-break rates in weaving.
The residual acetyl content reduces crystallinity and dry-state glass transition temperature, but it also lowers thermal stability relative to fully hydrolyzed PVOH. Thermogravimetric analysis in air shows measurable weight loss above 150 °C and rapid degradation above 200 °C, with acetic acid release. Melt processing without plasticizer is not recommended because the thermal degradation window is narrow; plasticized extrusion with polyols at 10–25 phr can be performed at barrel temperatures below 190 °C, but published data for this specific configuration is limited. The powder should be stored in sealed containers at relative humidity below 60%; prolonged exposure leads to lumping and reduced flow in screw feeders. Incompatibility with strong oxidizing agents, peroxides, and certain transition metal salts should be assumed unless compatibility testing indicates otherwise. Dust explosion hazards should be evaluated according to process safety data; the manufacturer’s dust cloud ignition parameters should be obtained before pneumatic conveying or vacuum transfer.
For compliance verification, the following matrix summarizes the primary assessment routes.
| Application context | Regulatory or test reference | Assessment boundary |
|---|---|---|
| Food-contact paper and paperboard | 21 CFR 176.170, 21 CFR 176.180 | Extractives limits and end-use temperature |
| Adhesive component for food packaging | 21 CFR 175.105 | Indirect food additive clearance |
| EU REACH registration | REACH polymer provisions | Residual vinyl acetate monomer monitoring |
| Electrical and electronic materials | RoHS 2011/65/EU | No restricted substances intentionally added |
| Property comparison | ISO 15023-2 | Density, ash, and residue testing |
In multi-ply tissue laminating and paper tube winding, the grade is applied at 6–12 wt% solids and dried on steam-heated drums at surface temperatures of 110–130 °C. The partially hydrolyzed film develops sufficient green tack when rewetted, but remains fully repulpable under mill conditions defined by TAPPI T 275 screening. Use of 0.2–0.5% of a suitable defoamer on formulation weight is common to prevent foam entrainment in high-speed laminating trays.
