| Código HS | 165674 |
| Producto | Wanwei PVA 20-92 (L) (PVA 092-35) |
| Nombre Químico | alcohol polivinílico |
| Cas Número | 9002-89-5 |
| Apariencia | polvo blanco o granulado |
| Grado De Hidrólisis | 92,0 ± 1,0% mol |
| Viscosidad 4 Solución 20c | 30,0 - 40,0 mPa · s (35 mPa · s nominales) |
| Grado Medio De Polimerización | 2000 |
| Ph 4 Solución 20c | 5,0 - 7,0 |
| Contenido Volátil | ≤ 5,0% |
| Contenido De Ceniza | ≤ 0,5% |
| Densidad Aparente | 0,4 - 0,6 g/cm³ |
| Tamaño De Partícula | Malla 20-80 |
| Solubilidad | Soluble en agua |
Como fábrica acreditada de Wanwei PVA 20-92 (L) (PVA 092-35), hacemos cumplir estrictos protocolos de calidad: cada lote se somete a rigurosas pruebas para garantizar estándares consistentes de eficacia y seguridad.
| Embalaje | Empaquetado en bolsas de polipropileno tejidas con revestimiento de polietileno neto de 20 kg, selladas para proteger contra la humedad, lo que garantiza una manipulación y almacenamiento seguros. |
| Carga De Contenedores (20 'FCL) | 20 'FCL: Wanwei PVA 20-92 (L) embalado en bolsas paletizadas, guardado de forma segura, protegido contra la humedad y contenedor sellado para un tránsito seguro. |
| Envío | Wanwei PVA 20-92 (L) se envía como polvo de alcohol polivinílico no peligroso. Debe mantenerse seco, ya que es higroscópico. Use bolsas o contenedores sellados y resistentes a la humedad, proteja de perforaciones y guárdelo lejos de la humedad y la lluvia directa. El flete estándar es adecuado, pero evite la contaminación con de materiales generadores de polvo. |
| Almacenamiento | Guarde Wanwei PVA 20-92 (L) en un área fresca, seca y bien ventilada lejos del calor, las chispas y la luz solar directa. Mantenga el recipiente original bien cerrado para evitar la absorción de humedad y la contaminación. Evite la acumulación de polvo y entre en contacto con con oxidantes fuertes. Utilice el equipo de protección personal adecuado al manipularlo y siga todas las regulaciones locales para un almacenamiento seguro. |
| Duración | La vida útil es de 12 meses desde la fabricación cuando se almacena en un embalaje original sellado en un lugar fresco y seco. |
In the production of polyvinyl acetate homopolymer and vinyl acetate-ethylene copolymer dispersions intended for wood assembly adhesives, Wanwei PVA 20-92(L) (alias PVA 092-35) functions as the primary steric stabiliser. The polymerisation adopts a semi-continuous pre-emulsion feed regime within a glass-lined jacketed reactor equipped with a 45°-pitch impeller and baffles. An initial reactor charge of deionised water and 4–8 wt% PVA 20-92(L) (on total monomer mass) is heated to 75–80 °C. Non-ionic surfactant is optionally dosed at 0.3–1.0 wt% to modulate particle nucleation without completely replacing the polymeric colloid, as total surfactant substitution leads to a lost shear-stress plateau in the final adhesive.
Monomer pre-emulsion containing vinyl acetate monomer, the shell of a redox initiator system (typically potassium persulphate/sodium metabisulphite), and buffer solution is metered in over 3–4 hours. The process control variable most tightly coupled to PVA grade is the minimum film-forming temperature of the finished emulsion, which shifts non-linearly when the residual polyvinyl alcohol acetate distribution broadens. Users report that dropping the PVA 20-92(L) charge under 3.5 wt% on monomer triggers secondary nucleation bursts, yielding a bimodal particle size distribution detectable by disc centrifuge photosedimentometry ISO 13318. The emulsion is cooled and post-stabilised with a biocide package before drumming. Industry compliance framework: FDA 21 CFR 175.105 (adhesive components in indirect food contact), GB 18583-2008 (limits for free formaldehyde and volatile organic compounds in interior architectural adhesives), and qualitative identity under EU REACH Regulation (EC) No 1907/2006. Terminal end-products include D3/D4 wood bonding adhesives (as classified by EN 204), paper lamination glue, and bookbinding hot-melt adhesives where the dispersion substitutes for bulk acrylic systems.
Operational incompatibility: direct addition of borax (sodium tetraborate) or boric acid to the colloid-stabilised emulsion causes an immediate and irreversible viscosity climb exceeding 50,000 mPa·s due to cross-bridging of the 1,3-diol units on the PVA backbone. Manufacturers running a ‘borated’ thickening step must pre-dilute borax to 0.5% solution and dose under high agitation; without this, induction period shortening in subsequent storage stability tests (ISO 13032-2) is observed.
On a Benninger Supertronic SMR-2 two-cylinder pre-wet sizing range processing 40s Ne 65/35 polyester/combed cotton warp yarns for high-density down-proof shirting fabric at 800 m/min, PVA 20-92(L) is the dominant filming binder in the size liquor. The volume of medium is held at 920 L in the circulating system with a solids content of 10.5 ± 0.5 %. Formulation of the size box: 100 parts oxidised corn starch (fluidity 62 BF), 35 parts PVA 20-92(L), 8 parts polyacrylic size as lubricating component, and 2 parts winding oil, the balance water. PVA is dissolved in a separate heated cook tank at 95 °C for 45 min under propeller agitation before being commingled with gelatinised starch. Real-time control of size pick-up at 12–14.5 % (dry mass on yarn) is achieved by regulating squeezing roller pressure (12–16 kN for the first nip). Sizing viscosity at 90 °C is maintained between 28–35 mPa·s (Brookfield LV #21, 100 rpm); excursions above 40 mPa·s produce a brittle brittle size film with increased lint shedding at the reed. After drying cylinder surface temperature 125–140 °C, the sized beams demonstrate a hairiness index reduction of 62–78 % relative to unsized warp (Zweigle G565 tester). The finished fabric passes OEKO-TEX® Standard 100 Annex 4 limits for residual vinyl acetate monomer and formaldehyde. Terminal textiles include 80 × 80 /230 × 195 down-proof taffeta and shirting poplin, where warp breakage rates on Tsudakoma ZAX9200i water-jet looms fell to 0.24 breaks per 100,000 picks in plant data logs.
When surface sizing high-brightness woodfree sheets on a Voith SpeedSizer with film-transfer metering, the replacing of a fraction of pigment coating binder with PVA 20-92(L) is driven by the requirement for IGT dry pick velocity above 3.5 m/s. The size press stock is prepared at 7.2 % solids and the portion of PVA 20-92(L) in the binder mix (predominantly styrene-acrylate latex and enzyme-converted starch) is tuned between 18–28 dry weight %. The liquor’s temperature at the blade is 62–68 °C. Viscosity stability across the blade is critical because partially hydrolysed PVA is more shear-stable than the alternative cationic starch but can undergo retrogradation-induced microgelation if the blade reservoir pH drifts below 5.0. For that reason, the wet-end additive programme must guarantee that the base paper’s surface pH exceeds 6.5.
The coating weight target is 1.2–1.8 g/m² per side, monitored through beta-ray or IR reflection gauges. Tuning the PVA 20-92(L) fraction above 30 dry weight % increases the dynamic water contact angle of the sized sheet beyond 85° after 10 s, which deteriorates the receptivity to water-based flexo ink on press, a phenomenon tracked via Emtec PDA.C 02 short-time measurement. Regulatory boundary: composition of the surface-sizing layer is subject to FDA 21 CFR 176.170 (components of paper and paperboard in contact with aqueous and fatty foods) and BfR Recommendation XXXVI. The finished outputs are 90 g/m² SBS folding cartonboard for dry food packaging and 128 g/m² C1S art paper for offset lithography, where the PVA fraction in the surface size recipe raised Dennison wax pick values by 2–3 units in mill qualification trials.
PVA 20-92(L) exhibits a cold-water dissolution spectrum that enables continuous cast film production for unit-dose applications without requiring a post-coating crosslinking step. The film stock is fabricated on a caterpillar-track conveyor solution-casting line with co-rotating L/D = 36 twin-screw extruder degassing of the aqueous PVA dope. The aqueous solution is prepared at 19–22 wt% PVA 20-92(L) with 15–20 parts of a plasticiser blend (glycerol/sorbitol/xylitol) per 100 parts resin, 0.5–1.2 wt% of release agent, and quaternary ammonium salt as anti-block modifier. A series of static mixers after the extruder head ensures that gel counts detected by inline 50 μm mesh screen remain below 5 particles per 10 m² of finished film. The casting curtain is spread onto a chromium-plated steel belt moving at 8–18 m/min and progressed through five drying zones from 65 °C (zone 1) to 108 °C (zone 5). Humidity profiling is critical: the feed section is held at 60 % RH to prevent skin-over, while the last zone exits at 12–14 % equilibrium moisture to avoid inter-layer blocking during wind-up.
In quality control, dissolution time—measured as the time for complete disintegration of a 76 μm-thick, 25 mm × 25 mm film coupon in 1 L deionised water stirred at 200 rpm at 20 °C—must fall within 22–36 s. In the pH range of commercial laundry liquid detergents (7.5–8.5), no statistically significant drift in dissolution half-life is observed; however, high-alkaline formulas with pH above 10.5 cause progressive crystallisation-driven oligomer re-association that extends dissolution time beyond 120 s after 8‑week storage at 37 °C. Test standards tethered to final product claims: ISO 14851 (ultimate aerobic biodegradability), EN 17017:2018 for soluble detergent packaging sheets, and ISO 15270 when claimed as biodegradable plastics. End products include PVOH film encasing liquid laundry capsules, water-soluble agricultural chemical sachets, and release film for cast composite components.
Spray-dried polymer-bound dispersible polymer powders based on ethylene-vinyl acetate copolymers utilise PVA 20-92(L) as the primary colloidal armour during emulsion synthesis and again as a post-added spray-drying aid. In the upstream polymerisation reactor, the protective colloid demand is 5–7.5 wt% based on vinyl acetate plus ethylene monomer feed; subsequent dilution to 47 % solids precedes the atomisation step. Drying is executed on a NIRO MOBILE MINOR™-type co-current pressure nozzle tower with an inlet temperature of 185–205 °C and outlet temperature clamped at 83–87 °C. The critical boundary is the outlet temperature: exceeding 92 °C causes the PVA shell to thermally fuse, yielding non-redispersible grit that fails the EN 12004 mineral surface bond strength retention test after immersion. The powder is post-blended with 8–12 % fine SiO₂ anti-caking agent, then packed in moisture-resistant aluminium-foil bags. In the downstream dry-mix formulation—a C2TE S2 ceramic tile adhesive conforming to EN 12004:2007—the content of redispersible powder containing PVA 20-92(L) is 3.5–5.0 % on cement weight. Compound storability is limited to 6 months at 20 °C/50 % RH due to gradual plasticiser migration into hygroscopic filler particles.
In the non-aqueous tape-casting process for 96 % Al₂O₃ thin-film electronic substrates, the low-ash designation of PVA 20-92(L) (residual sodium <200 ppm, residual iron <50 ppm) meets the ionic cleanliness requirement for microwave dielectric laminates. The tape-casting slurry is blended in a planetary centrifugal mixer: 100 parts alumina powder (D₅₀ 0.8 μm), 35–45 parts MEK/ethanol azeotrope solvent system, 3.5–4.2 parts PVA 20-92(L) as sacrificial binder, 1.8–2.5 parts dibutyl phthalate plasticiser, and 0.4 parts phosphate ester dispersant. After deaeration under 20 mbar vacuum, the slurry is doctor-bladed onto silicone-coated PET carrier film at a gap of 200–280 μm and line speed of 0.5–1.2 m/min. Drying is executed in a two-zone convection channel with zone 1 at 50 °C and zone 2 at 70 °C, holding green tape moisture below 0.5 wt% before peeling.
The burnout profile is validated against DIN 51085-style thermogravimetry: linear ramp to 280 °C at 1 °C/min, hold for 60 min to volatilise plasticiser, then ramp to 600 °C at 3 °C/min and dwell for 120 min to oxidise the PVA backbone. Residual carbon measured by coulometric detection must fall below 0.04 wt%, otherwise co-fired silver-palladium conductor paste suffers blistering. The sintering step proceeds at 1,580–1,620 °C in an air atmosphere to reach ≥ 96 % theoretical density. A known limitation when using partially hydrolysed PVA binders is the increased hygroscopicity of the green tape: ambient exposure beyond 2 hours at RH> 55 % induces 3D swelling and via-hole misregistration exceeding ±0.15 mm on a 200 mm × 200 mm panel. Finished components include microstrip antenna substrates, thick-film hybrid circuit boards, and multi-layer ceramic capacitor (MLCC) dielectric sheets where the binding phase burnout behaviour directly influences loss tangent (tan δ) at 1 MHz per IEC 60384-8.
| Application | Input concentration of PVA 20-92(L) | Critical process window | Primary compliance code |
|---|---|---|---|
| PVAc/VAE emulsion protective colloid | 4–8 wt% on total monomer | 75–80 °C reactor temp; do not charge <3.5 wt% to avoid bimodal PSD | FDA 21 CFR 175.105, GB 18583-2008 |
| Polyester/cotton warp sizing | 35 parts in size formulation with 100 parts starch | Squeeze pressure 12–16 kN; size liquor viscosity 28–35 mPa·s | OEKO-TEX® Standard 100 |
| Coated fine paper surface sizing | 18–28 dry wt% of total binder | pH at blade > 5.0; base sheet surface pH > 6.5 | FDA 21 CFR 176.170 |
| Water-soluble unit-dose film | 19–22 wt% in aqueous dope | Drying humidity zone 1: 60 % RH; final moisture 12–14 % | EN 17017:2018 |
| Spray-dried redispersible powder | 5–7.5 wt% on monomer; post-add in emulsion | Outlet air 83–87 °C; 92 °C triggers non-redispersible grit | EN 12004 |
| Tape-casting electronic ceramic | 3.5–4.2 parts per 100 parts Al₂O₃ | Burnout hold at 280 °C 60 min; green tape exposure <2 h at RH 55 % | IEC 60384-8 (MLCC tan δ) |
An additional formulation note common to all aqueous PVA 20-92(L) mixtures: dry powder must be stored at <30 °C and <60 % RH. Solution preparation requires slow sifting of powder into a vortex of water at 20–25 °C followed by heating to 85–95 °C with constant agitation for at least 30 min; cold slug addition directly to hot water results in undispersed ‘fish-eye’ cores that resist full hydration and show up as micro-gels in sizing or coating operations.
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Wanwei PVA 20-92(L) — also distributed in certain regional markets under the designation PVA 092-35 — is a partially hydrolysed polyvinyl alcohol grade characterised by a nominal viscosity of 20–25 mPa·s (measured as a 4% aqueous solution at 20 °C per ISO 15023-2:2019) and a degree of hydrolysis controlled within 91.0–93.0 mol%. The residual acetyl content, determined by saponification value according to ISO 15023-1:2019, ranges between 100 and 120 mg KOH/g. Ash residue after ignition at 800 °C is specified at ≤0.5 wt%, and the pH of a 4% aqueous solution falls at 5.0–7.0. The powder exhibits a bulk density of 0.40–0.60 g/cm³ and passes a 80-mesh screen with ≥90% retention. This balance of medium molecular weight and controlled lipophilic character positions the grade as a multipurpose stabiliser, temporary binder, and film former in water-based industrial formulations, where full cold-water solubility and adequate intercoat adhesion are required without the excessive hygroscopicity of lower-hydrolysis grades.
In the manufacture of aqueous vinyl acetate-ethylene (VAE) copolymer dispersions in 10–25 m³ stirred stainless-steel reactors fitted with multi-stage impellers (80–120 rpm), PVA 20-92(L) functions as the primary protective colloid. Charged at 3–6 pphm (parts per hundred monomer) into a pre-emulsion along with a persulphate initiator at 0.2–0.5 wt%, the polymer chains undergo partial grafting reactions with the growing PVAc backbone, generating a steric barrier that controls both particle nucleation and coalescence. Industrial trials show that substituting a fully hydrolysed grade (e.g., 99+ mol%) with 20-92(L) depresses the final latex particle size distribution (PSD) from 800–1200 nm to 400–700 nm, as measured by dynamic light scattering (ISO 22412:2017). The lower acetoxy surface excess, expressed as the surfactant-to-colloid transition concentration, reduces the risk of foaming in the reactor headspace. However, the grafting efficiency is sensitive to the dissolved iron content in the vinyl acetate monomer; when Fe2+ exceeds 2 ppm, an induction period of 20–40 s followed by an exotherm overshoot of +8 °C has been recorded at commercial scale, necessitating the addition of 50–100 ppm EDTA tetrasodium as a metal chelator. The resulting dispersion’s shear-rate-dependent flow curve, fitted to a Carreau–Yasuda model, shows a zero-shear viscosity 5–15 Pa·s and a power-law index 0.35–0.45 at 25 °C, data points critical for designing downstream transfer pumping and filter screen packs.
Dewatering behaviour of size films was evaluated on a Benninger warp sizing line operating at 75 m/min. A 6% solids bath containing PVA 20-92(L) combined with a potato starch ether (1:1 w/w) exhibited a size pick-up of 10.5–11.2% on ring-spun cotton yarn (30 Ne). The residual acetate groups soften the film morphology, imparting a glass transition temperature (Tg) of 62 °C as determined by differential scanning calorimetry (ASTM E1356), 15 °C lower than that of a 98–99 mol% hydrolysed grade. This depression reduces lint shedding in the split rod zone and cutting rail by 30–45%, quantified by gravimetric lint collection over 5000 loom cycles. Nonetheless, the sensitivity to condensation-induced hydrolysis must be accounted for: size boxes held overnight at pH >9.5 by residual desizing enzymes from previous lot changes triggered a viscosity decay greater than 15%, highlighting the need for alkaline buffer removal prior to makeup.
Polyvinyl alcohol wood adhesives formulated with 20-92(L) typically contain 10–14 wt% of the polymer, together with a polyvinyl acetate emulsion, calcium carbonate filler (30–50 µm median particle size), and a plasticiser such as dibutyl phthalate or a citrate ester. Wet tack development, measured by a probe-tack tester (ASTM D2979-16) on a birch veneer substrate conditioned at 23 °C, 50 % RH, follows a profile that reaches 0.8 N/mm² within 12–18 s, then plateaus at 1.2–1.5 N/mm² after 60 s. The partially hydrolysed structure yields an open assembly time on a porous beech surface of 8–12 min at 20 °C — approximately 4–6 min longer than an equivalent 88 mol% grade, due to slower water release governed by hydrogen bonding. During hot pressing at 110 °C, 0.8 MPa for 3 min, the bond line remains cohesive; no phase separation between PVA and the filled PVAc phase has been observed by scanning electron microscopy at 2000× magnification. A documented processing constraint arises when urea-formaldehyde or melamine-formaldehyde hardeners are incorporated to meet D3 or D4 durability classification (EN 204/205): pre-reaction between the hydroxymethyl groups and the PVA hydroxyls can cause a gelation front inside the static mixer elements within 45 min at 30 °C, forcing a shift to two-component application ahead of the static mixer.
Solution-cast multilayer films incorporating an oxygen barrier interlayer of 20-92(L) deposited from 15 wt% aqueous solution on a Böhnhardt film stretching line display an oxygen transmission rate (OTR) of 12–18 cm³·mm/(m²·d·atm) at 23 °C, 0 % RH when measured per ASTM D3985-17. Raising the relative humidity to 50 % elevates the OTR to 35–50 cm³·mm/(m²·d·atm), a permeability penalty attributed to plasticisation of the amorphous phase by sorbed water, which disrupts the interchain hydrogen-bond network responsible for gas barrier function. In contrast, a fully hydrolysed grade (hydrolysis degree >99 mol%) delivers OTR values of 1–5 cm³·mm/(m²·d·atm) under identical dry conditions, but requires dissolution at 95–98 °C and subsequent cooling to 35–40 °C over 90 min to avoid gel particle formation — a processing window that 20-92(L) expands significantly, dissolving rapidly at 40–45 °C without need for a temperature ramp. This trade-off positions 20-92(L) where moderate barrier performance suffices but ambient-temperature handling of the casting solution is mandatory, such as in pharmaceutical strip packaging where the cast film is thermally laminated between two polyethylene layers with an ethylene-acrylic acid adhesive tie coating at 90 °C, conditions where pinholing due to PVA film brittleness is eliminated owing to the grade’s lower crystallinity (the X-ray crystallinity index determined by peak deconvolution of the 2θ = 19.4° reflection stays below 28%).
| Property | Method | 20-92(L) | 17-99 | 20-99 | 05-88 |
|---|---|---|---|---|---|
| 4% solution viscosity (mPa·s) | ISO 15023-2 | 20–25 | 25–30 | 21–26 | 4.5–6.5 |
| Hydrolysis degree (mol%) | ISO 15023-1 | 91.0–93.0 | 99.0–99.5 | 99.0–99.5 | 86.5–89.0 |
| Ash (wt%) | ISO 3451-5 | ≤0.5 | ≤0.5 | ≤0.5 | ≤0.5 |
| Film tensile strength (MPa) | ISO 527-3 | 44–52 | 60–70 | 58–68 | 28–35 |
| Elongation at break (%) | ISO 527-3 | 150–200 | 70–110 | 80–120 | >250 |
| Dissolution temperature (°C) | Internal method | 35–50 | 90–98 | 92–100 | 18–30 |
When 20-92(L) partially replaces oxidised corn starch in a coating colour destined for a blade coater running at 1200 m/min, the Brookfield viscosity at 100 rpm shifts from 1200 mPa·s to 800–950 mPa·s at the same solids content, allowing an increase in coating solids from 58% to 63% while maintaining a stable dynamic water retention value (AA-GWR, 1.5 bar) of 50–65 g/m². The IGT pick strength (ISO 3783) improves to 2.8–3.2 m/s, attributed to a binder migration pattern that concentrates the PVA near the surface during the drying phase of a short-dwell evaporation zone at 250 °C web temperature. The partially hydrolysed grade generates a surface film free of excessive water sensitivity: the Cobb60 water absorption (ISO 535) of the dried coating is 25–28 g/m², compared to 18–20 g/m² for a fully hydrolysed PVA and 42–48 g/m² for the starch-only reference. An acknowledged operational boundary is the interaction with optical brightening agents (OBAs) of the tetrasulfonated stilbene class; at addition levels above 0.4 wt%, the formation of a PVA–OBA charge-transfer complex causes a visible yellowing (Δb*> +2.5) upon exposure to UV light in accelerated weathering chambers (ASTM G154).
| Regulation | Scope | Status |
|---|---|---|
| EU 10/2011 (amended) | Plastic materials and articles intended to come into contact with food | Monomers/additives listed; specific migration limit (SML) of the polymer generally not required due to high molecular weight; residual vinyl acetate monomer <2 mg/kg verified by HS-GC-MS per EN 13628-2. |
| FDA 21 CFR 175.300 | Resinous and polymeric coatings for food contact | Substance listed as component of coatings for repeated use; extractives limitation 0.5 mg/in² in food-simulating solvents D, E, and F. |
| FDA 21 CFR 176.170 | Components of paper and paperboard in contact with aqueous and fatty foods | Component of sizing additives; GMP compliance requires extractives not to exceed 0.5 mg/in² for paper and paperboard. |
| FDA 21 CFR 177.1670 | Polyvinyl alcohol film for dry food contact | Permitted subject to maximum water-extractable fraction specifications; PVA grade with viscosity >5 mPa·s acceptable. |
| REACH (EC) 1907/2006 | Registration, Evaluation, Authorisation of Chemicals | Polymer exemption applied; registration not required per REACH Article 2(9). Monomer VAM registered; supplier has confirmed SVHC content below 0.1% w/w. |
| RoHS 2011/65/EU | Restriction of hazardous substances in electrical and electronic equipment | Not in scope for the polymer itself; cadmium, lead, mercury, chromium VI, PBBs/PBDEs below threshold if used as processing aid in EE applications. |
Material stored in open bags at ambient conditions exceeding 30 °C and 80 % RH for >72 h will exhibit lump formation and a moisture uptake of 3–5 wt%, which introduces feeding inconsistencies in gravimetric screw dosing systems (e.g., Brabender or K-Tron singe-screw feeders with D=20 mm, L/D 22:1) and requires pre-sieving through a 1.4 mm mesh. Stock solutions held without biocide at 20–25 °C exhibit a mould growth onset visible to the unaided eye after 5–7 days; addition of 0.05–0.1 wt% of a methylisothiazolinone/benzisothiazolinone blend (3:1 ratio) extends fluid service life to 90 days. Crosslinking of 20-92(L) solutions with glyoxal at molar aldehyde-to-hydroxyl ratios above 0.15 should be avoided in formulations that will be stored at pH <4.0, because the rapid formation of cyclic acetal structures increases the viscosity beyond the point of spray atomisation (>200 mPa·s) within 30 min, rendering the delivery system inoperable.
When used as a carrier resin in ceramic body extrusion, addition of 2–4 wt% 20-92(L) (based on dry ceramic mass) reduces the plasticity index of an alumina slip (prepared from A-16 SG powder, surface area 9.5 m²/g) from 28 mm to 17–19 mm (Pfefferkorn method), while retaining a green strength of 1.8–2.5 MPa measured by 3-point bending according to ASTM C1161. The sintering burnout profile demands a heating ramp in air to 600 °C at a rate of 0.5 °C/min between 180 °C and 280 °C, the interval where the exothermic decomposition of the residual acetate groups takes place; exceeding 1 °C/min in this zone has caused blistering and delamination of extruded honeycomb catalyst substrates observed in production-scale tunnel kilns.
