| HS Code | 328522 |
| Appearance | White milky liquid |
| Solid Content | 55 ± 1% |
| Viscosity | 5000 - 10000 cP (Brookfield, 25°C) |
| Ph | 4.0 - 6.0 |
| Particle Size | 0.5 - 2.0 μm |
| Glass Transition Temperature | 28 - 32°C |
| Minimum Film Forming Temperature | 15 - 20°C |
| Film Stiffness | High, rigid film |
| Water Resistance | Good |
| Adhesion To Substrates | Strong to wood, paper, and fiber |
| Mechanical Stability | Excellent under shear |
| Ionic Type | Nonionic |
As an accredited PVAc Stiffening Agent factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PVAc Stiffening Agent supplied in 5 kg sealed plastic pails, with secure, labeled packaging for safe handling and storage. |
| Container Loading (20′ FCL) | 20′ FCL: palletized drums/IBCs of PVAc stiffening agent, securely braced, labeled, and ventilated for safe transport. |
| Shipping | PVAc Stiffening Agent ships as a non-hazardous aqueous polymer dispersion when no dangerous constituents are present. Transport in sealed, labeled containers to prevent leakage. Avoid freezing and excessive heat. Standard freight is acceptable; no UN classification required unless additive hazards apply. Ensure proper ventilation and spill containment during transit and handling. |
| Storage | Store PVAc Stiffening Agent in tightly sealed, original containers in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and ignition sources. Protect from moisture and freezing. Keep containers upright to prevent leakage. Ensure compatibility with storage materials and segregate from strong oxidizers or incompatible chemicals. Label clearly and follow manufacturer’s safety guidelines. |
| Shelf Life | Store unopened in a cool, dry place; shelf life is typically 12 months from manufacture date when properly sealed. |
Fusible interlining production on 35–55 g/m² point-bonded polyester or polyester/viscose nonwovens requires a stiffening saturant that does not shift the base fabric handle into paper-like deadness and does not crack along hot-melt paste lines during die cutting. A carboxylated polyvinyl acetate dispersion with glass transition temperature between 28 °C and 35 °C, buffered to pH 5.0–6.5 with sodium bicarbonate, is applied on a pad-mangle at 2.5–4.0 bar nip pressure. Wet pick-up is adjusted to 60–70% by dilution to 18–22% solids. Dry add-on below 12 g/m² creates a discontinuous matrix around fibre intersections, producing a bending length increase above 45% in machine direction but preferential cracking along low-binder zones when a blade cutter runs at 55–75 strokes/min. Full cure of self-crosslinking AAEM/ADH grades at 140–150 °C for 50–70 s on a stenter with 25 m heated chamber is required to develop wet flexural strength. The terminal interlining product must retain ≥80% of initial bending length after 5 washing cycles according to ISO 6330:2021 procedure 4N at 40 °C. Formaldehyde content is monitored against OEKO-TEX Standard 100 class II limits because NMA-crosslinking grades can release 75 mg/kg or more unless a formaldehyde scavenger is post-added. Production-scale edge curl failures on rotary cutting tables typically originate from residual moisture above 4% in board-packed interlining. Pre-drying at 80–90 °C for 20–30 s before cure prevents warp-direction shrinkage. At line speeds above 60 m/min, drying capacity rather than cure kinetics becomes the limiting variable. The same dispersion is not suitable for continuous filament polyester nonwovens above 80 g/m² because high wet pick-up causes binder migration to the surface and delamination under ASTM D2724-19 peel loading.
Saturation of cylinder-machine kraft base paper with a carboxylated polyvinyl acetate stiffening dispersion at 110–150 g/m² dry pick-up alters cross-machine stiffness and surface receptivity for phenolic or urea-formaldehyde resin coatings in coated abrasive backings. The saturant is applied on a flooded nip coater with a 0.3–0.5 mm gap between a grooved steel roll and a 75–85 Shore A rubber backing roll at line speeds of 80–120 m/min. The first dryer can section is held at 70–90 °C to prevent skin-over and bubble formation; the final section is raised to 110–130 °C to drive off unreacted water and promote film coalescence. The base paper typically has a Gurley stiffness of 180–240 mgf before saturation and a Cobb value of 35–45 g/m² according to ISO 535:2014. After stiffening, tensile energy absorption in machine direction increases from 0.9 J/m² to 1.5–2.8 J/m² measured with ISO 1924-2:2008. The carboxylic acid functionality on the PVAc backbone provides adhesion to calcium carbonate filler but is sensitive to alkaline process water above pH 8.5; at higher pH, ester hydrolysis reduces molecular weight and causes loss of saturant cohesion in aqueous resinated abrasive cloth preparation. The stiffened paper is subsequently coated with a urea-formaldehyde or phenol-formaldehyde resin layer and grain-bonded with aluminium oxide or silicon carbide. Terminal products include flexible abrasive belts, sheets, and discs for wood and metal finishing. Environmental compliance for the saturant is covered by European REACH Regulation (EC) No 1907/2006 and, where the coated abrasive packaging may contact food, FDA 21 CFR 176.170 and FDA 21 CFR 176.180 migration testing. At RH above 65%, the saturated paper absorbs moisture and loses 15–25% of measured stiffness within 24 h; preconditioning at 23 ±1 °C and 50 ±2% RH according to TAPPI T 402 is mandatory before comparing lot-to-lot data.
| Application | Standard / method | Measured property | Typical industrial acceptance band | Boundary condition |
|---|---|---|---|---|
| Fusible interlining | ISO 6330:2021 procedure 4N | Bending length retention | ≥80% after 5 washes | Formaldehyde release <75 mg/kg under OEKO-TEX Standard 100 class II |
| Abrasive paper saturant | ISO 1924-2:2008 | Machine-direction tensile energy absorption | 1.5–2.8 J/m² | pH 8.5 maximum to avoid ester hydrolysis |
| Filter pleat fixation | ISO 5636-3:2013 | Air permeance after pleating | 220–340 L/m²/s at 200 Pa | Cure 140–150 °C for 60–90 s |
| Warp sizing | ASTM D2256/D2256M-21 | Sized yarn tenacity retention | 85–92% of unsized yarn | Effluent COD <20 000 mg/L before dilution |
| Glass mat binder | ISO 3342:2011 | Glass mat tensile strength | 80–130 N/50 mm | Formaldehyde-free option required for indoor exposure |
| Bookboard lamination | ISO 2493-1:2010 | Bending resistance at 15° | 8–14 N·mm for 1.8 mm board | Stack pressure <35 kPa |
Cellulose filter media for engine air intake or HVAC pleated panels is stiffened before pleating so that pleat spacing remains open under high air flow and vibration. A self-crosslinking PVAc dispersion containing acetoacetoxyethyl methacrylate and adipic dihydrazide is typically diluted to 10–14% solids and applied by kiss roll or electrostatic spray at 2–6 g/m² dry add-on on the downstream face only. The media thickness is 0.45–0.65 mm, with base Frazier air permeability between 450 L/m²/s and 650 L/m²/s at 200 Pa. After stiffener application, air permeance drops by 8–15% according to ISO 5636-3:2013 while pleat stiffness measured with a Gurley-type tester TAPPI/ANSI T 543 om-22 increases from 250 mgf to 420–600 mgf. Curing in a direct gas-fired oven at 140–150 °C for 60–90 s is required; lower temperatures leave unreacted crosslinking sites that can cause pleat creep in humid service. Process conflict arises because excessive dry add-on above 7 g/m² forms a film on the downstream face and reduces dust-holding capacity by 15–20% in ISO 5011 multi-pass testing, while insufficient add-on below 2 g/m² does not prevent pleat deformation at 200–300 m³/h flow through a passenger car air filter element. Terminal products include pleated engine air intake filters and HVAC panel filters. Compliance for automotive under-hood components includes ISO 16232 cleanliness and volatile organic compound screening under VDA 278:2011. At sustained service temperatures above 75 °C, plasticized PVAc grades soften and allow pleat collapse unless a harder copolymer with Tg above 40 °C is selected; however, such hard grades require higher drying temperatures and have shorter open bath stability under circulation shear.
In shuttle looms running at 380–520 picks/min, PVAc-based stiffening sizes reduce hairiness-induced warp stops when add-on is controlled between 6% and 9% of dry yarn mass. A typical size formulation contains 8–12% solids from a plasticized non-crosslinking PVAc dispersion, 2–4% partially hydrolysed polyvinyl alcohol, and 0.3–0.8% ester wax. The size is applied on a multi-cylinder sizing machine with 7–12 dryer cans, first can temperature 100–110 °C and final can 120–130 °C, at size box temperature 60–70 °C. Sized ring-spun cotton yarn of 20–30 tex shows tenacity retention of 85–92% of unsized yarn under ASTM D2256/D2256M-21. The terminal woven fabrics include cotton workwear, canvas, and stiff polyester/cotton blends. The main processing boundary is desizing: non-crosslinking PVAc is not fully removed by hot water alone and requires an alkaline scour at 70–85 °C with 3–5 g/L sodium carbonate and 1–2 g/L nonionic detergent. When this scour is shortened below 20 min, residual polymer resolidifies in cold washing and causes visible size marks in pad dyeing. Effluent chemical oxygen demand from PVAc desizing varies with the machine liquor ratio, but direct discharge without treatment can exceed 20 000 mg/L COD before dilution. Mills reporting to the ZDHC Manufacturing Restricted Substances List must screen the size formulation for alkylphenol ethoxylates and restricted preservatives before use. Self-crosslinking PVAc grades must not be used for warp sizing because the cured film resists alkaline desizing and can be removed only by solvent scouring, which is not compatible with standard woven textile processing lines.
Glass mat for asphalt shingle base is formed on an inclined wire wet-lay machine at 80–120 m/min, and the wet mat is bound with a water-based binder before asphalt saturation. PVAc stiffening agent is used as a formaldehyde-reduced or formaldehyde-free alternative to standard urea-formaldehyde binders, typically blended at 15–30% of total binder solids when hot tensile strength is moderate. On production lines, the binder is applied by curtain coater or suction slot coater at 12–18% solids and dried in a through-air oven at 160–180 °C for 20–40 s; the mat exits with 0.5–1.5% moisture. Hot-drum handling at 70 °C imposes a storage modulus requirement above 500 MPa at 70 °C measured by dynamic mechanical analysis on free film. Non-crosslinked PVAc with Tg below 35 °C fails this requirement and can transfer to metal rolls, causing wrap-up stops. Blending PVAc stiffener with urea-formaldehyde at a 70:30 to 50:50 ratio raises glass mat tensile strength to 80–130 N/50 mm under ISO 3342:2011 and improves hot-wet strength, but formaldehyde release becomes the limiting compliance parameter. Formaldehyde-free AAEM/ADH grades achieve lower hot-wet strength and published data for long-term asphalt compatibility in shingle manufacture is limited. Terminal product is fiberglass asphalt shingle substrate with basis weight 60–110 g/m². The glass mat must also pass tear strength and asphalt saturation rate tests; PVAc-rich binders slow asphalt penetration because PVAc is partially swollen by bitumen, so binder content above 40% PVAc is avoided unless a permeability promoter is used. Storage of unshingled mat at >80% relative humidity causes hygroscopic softening and must be prevented with sealed wrap and desiccant.
Initially applied by roller coater at 2–4 g/m² wet film weight to 1.8 mm greyboard, PVAc stiffening agent raises board bending resistance without causing blocking at stack pressures below 35 kPa. The dispersion is formulated at 40–50% solids with a plasticizer content of 5–10% on dry polymer to maintain flexibility at the spine fold. Drying in a hot air tunnel at 60–80 °C for 30–60 s leaves a clear film with open time of 30–60 s at 25 °C and 50% RH. Book cover boards laminated with polyester or paper book cloth show peel adhesion above 5 N/25 mm under ASTM D903-98(2017). Bending resistance measured by ISO 2493-1:2010 at 15° increases from 4–6 N·mm to 8–14 N·mm, which allows unsupported cover lay-flat performance without excessive board curl. The main process failure is blocking after guillotine cutting: if stacked at pressures above 35 kPa and temperatures above 35 °C, the coated surface can adhere to adjacent board. Use of a 1–2% paraffin wax dispersion in the PVAc formulation reduces blocking but also lowers print adhesion on subsequent offset lithographic coating. Terminal products include hardcover book boards, ring binder covers, and rigid stationery packaging. For materials intended for indirect food contact through printed and converted packaging, migration of residual vinyl acetate monomer is screened against EU Regulation (EU) No 10/2011 and FDA 21 CFR 176.170; residual vinyl acetate monomer in the raw emulsion is specified below 500 mg/kg by the supplier. This application does not require a curing crosslinker, and addition of one may cause spine cracking during board scoring.
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PVAc stiffening agent is supplied as an aqueous polyvinyl acetate homopolymer dispersion stabilized with polyvinyl alcohol protective colloid, formulated to yield a rigid film without plasticizing comonomers. The product’s model designation is typically tied to nominal solids and particle-size class; a 45% solids grade is used here as the reference configuration. Solids content is controlled at 45 ± 1% by ISO 3251, Brookfield viscosity at 25 °C and 20 min⁻¹ is 8,000–16,000 mPa·s by ISO 2555, pH is 4.5–5.5 by ISO 976, and minimum film-forming temperature is 16–18 °C by ISO 2115. Glass transition temperature measured by differential scanning calorimetry is 30–33 °C under ASTM D3418. Residual vinyl acetate monomer is below 0.1% by ISO 13741-1.
Typical applications are textile warp sizing, paper and paperboard surface sizing, nonwoven impregnation, and rigid wood assembly adhesives. In comparison with vinyl acetate-ethylene dispersions of equivalent solids, the stiffening grade produces films with higher Shore D hardness determined by DIN EN ISO 868 and lower elongation at break; in comparison with acrylic or styrene-acrylic binders, it provides greater dry film modulus but reduced resistance to alkaline hydrolysis and exterior weathering. Because the dispersion is anionically stabilized at acid pH, direct blending with acid-sensitive fillers or cationic additives can coagulate unless pre-dilution and buffering are applied.
| Parameter | Test method | Typical specification range | Process consequence |
|---|---|---|---|
| Solids content | ISO 3251 | 45 ± 1% | Controls add-on, drying demand, and final film thickness |
| Brookfield viscosity | ISO 2555 at 25 °C, 20 min⁻¹ | 8,000–16,000 mPa·s | Requires progressing cavity or diaphragm feed pumps below 0.3 MPa |
| pH | ISO 976 | 4.5–5.5 | Acid pH limits direct addition to calcium carbonate slurries |
| Minimum film-forming temperature | ISO 2115 | 16–18 °C | Coalescing solvent demand increases below 16 °C |
| Glass transition temperature | ASTM D3418 | 30–33 °C | Film hardness and blocking resistance increase with Tg |
| Particle size | ISO 22412 | 0.8–2.0 µm | Affects shear stability and penetration into porous substrates |
| Residual vinyl acetate monomer | ISO 13741-1 | below 0.1% | Supports low-odor handling and industrial hygiene requirements |
Compared with starch-based sizing agents, the PVAc stiffening agent does not require cooking and is not susceptible to enzymatic attack by amylase; however, desizing follows an alkaline route rather than conventional enzymatic degradation. Compared with polyvinyl alcohol, the product produces lower water solubility and higher resistance to blocking in stacked films. Acrylic and styrene-acrylic binders generally provide better wet pick and ultraviolet resistance but can require higher addition levels to achieve equivalent dry flexural rigidity. At 25 °C, the dispersion is pseudoplastic; viscosity at 20 min⁻¹ is not sufficient to predict high-shear behaviour. Capillary rheometry at 1,000 s⁻¹ shows shear thinning to 400–800 mPa·s, depending on batch. Metering systems with progressing cavity pumps should operate below 0.3 MPa; higher pressure can cause mechanical shear and grit formation. Diaphragm pumps are preferred for transfer. Batch-to-batch viscosity variance is typically ±5% within a lot; inter-lot variance should be monitored by ISO 2555 after 24 h conditioning at 25 °C.
Film formation occurs by particle coalescence above 16–18 °C; below this temperature, 2–5% of a coalescing solvent such as propylene glycol or butyl diglycol is required to avoid discontinuous film formation. The dried film is water-sensitive and undergoes water whitening, with loss of tensile strength after immersion. Bonds prepared with the unmodified product generally meet DIN EN 204 D1 dry interior requirements but do not reliably satisfy D2 or D3 wet exposure classes without crosslinking.
Alkaline hydrolysis of acetate ester groups accelerates above pH 9 and above 60 °C. Cleaning with sodium hydroxide solutions should therefore be limited to short contact, and amine-based additives should be avoided because they raise pH, destabilize the anionic polyvinyl alcohol-protected dispersion, and promote hydrolysis. Crosslinking with 5–10 parts of polymeric methylenediphenyl diisocyanate or glyoxal-based hardener per 100 parts dry polymer shifts performance toward D2 service, but pot life is reduced to 2–4 h at 23 °C. Preconditioning of specimens at 23 °C and 50% RH according to ISO 291 is required before mechanical testing to avoid moisture-dependent scatter.
For porous substrates stored above 60% RH, pre-drying is required because adsorbed moisture interferes with film coalescence and reduces blocking resistance. Published data for high-humidity open-time limits on this specific product configuration is limited; qualification trials should include boundary-condition testing at the upper humidity and lower temperature of the intended service range.
For warp sizing on single-end or multi-cylinder sizing machines, the dispersion is diluted to 6–12% solids in the size box. Add-on is maintained at 8–14% of dry warp mass; squeeze-roll pressure is set to 0.2–0.4 MPa, and drying cylinder surface temperature is held at 110–130 °C. Viscosity at 60 °C is approximately 40–60% lower than at 25 °C, so circulation pump speed and level control require adjustment after thermal equilibration. Filtration through a 100 µm screen reduces dried-grit agglomerates that can deposit on immersion rollers.
Because PVAc is not degraded by amylase, desizing requires alkaline scouring at 70–80 °C with 2–4 g/L sodium hydroxide and 1–2 g/L nonionic wetting agent. Overdrying above 150 °C increases insolubility and contributes to warp brittleness. Comparative weaving performance is assessed by warp stops per 100,000 picks; published data for this specific sizing-machine configuration is limited.
In coated paperboard, the stiffening agent is used at 2–5 parts per 100 parts pigment as a co-binder. The coating color should be buffered to pH 8.0–9.0 before PVAc addition to avoid shock coagulation with ground calcium carbonate or clay slurries. High-shear mixing above 10,000 s⁻¹ requires an additional hydroxyethyl cellulose or polyvinyl alcohol stabilizer to prevent shear-induced grit formation.
Bending stiffness is measured by ISO 2493, and surface pick is measured by ISO 3783. Coatings containing PVAc stiffening agent typically show higher dry pick resistance than all-starch or protein binders but lower wet pick than styrene-acrylate systems after 24 h water contact. Blocking resistance at 40 °C and 5 kPa for 16 h is maintained when free film moisture is below 0.5%; calendering nip loads above 180 kN/m can reduce bending stiffness by film compaction. Water absorption by ISO 62 is higher than acrylic and styrene-butadiene alternatives, which limits use in exterior coatings; however, dry tensile strength measured by ISO 527-2 and flexural modulus remain adequate for rigid paperboard applications.
On blade coaters above 1,200 m/min, shear heating can raise colour temperature to 45 °C and reduce viscosity by 20–30%; runnability testing prior to full production is required because streaking and blade deposit formation depend on the co-binder package. The suspension should be introduced after pigment dispersion and stabilizer addition, not before, to minimize acid-induced destabilization of calcium carbonate.
Because PVAc stiffening agent produces a hard, non-blocking film at room temperature, it is used in nonwoven interlinings and abrasive paper backings where flexural rigidity must be increased without excessive surface tack. On a padding mangle, nip pressure is set to 0.15–0.40 MPa and binder add-on to 15–25% of fibre mass. Drying and crosslinking are conducted at 130–150 °C for 2–5 min; overcure above 160 °C causes film embrittlement and loss of flexural fatigue resistance.
For foam or spray impregnation, viscosity is reduced by dilution to 20–30% solids, yielding 100–500 mPa·s at 25 °C. Continuous circulation at shear stress below 0.4 MPa causes negligible viscosity drift, but drying of residues on can surfaces requires warm-water removal before dehydration. Tensile stiffness and bending length are determined by ISO 9073-2 and ISO 9073-7. Add-on above 25% can form a continuous surface film and reduce absorbency; process trials should therefore bracket the intended wet pick-up rather than extrapolate from lower add-on data.
In exterior-grade wood bonding, the use of PVAc stiffening agent as the sole binder is not recommended because the polyvinyl acetate backbone undergoes hydrolysis under sustained moisture. Joints intended for DIN EN 204 D2 or D3 service require addition of 5–10 parts of polymeric methylenediphenyl diisocyanate or melamine-formaldehyde per 100 parts dry polymer, and qualification should follow EN 302-1 load-bearing adhesive tests. Formulations containing isocyanate crosslinkers have a reduced pot life of 2–4 h at 23 °C; viscosity rises sharply after 4 h, and applicator roll transfer becomes non-uniform. Open assembly time is likewise shortened, requiring faster press closing and consistent component temperature conditioning.
Amine-based additives, ammonia, or cationic surfactants should be avoided because they raise pH, destabilize the anionic dispersion, and accelerate acetate hydrolysis. Where exterior water resistance is required, blending with a vinyl acetate-ethylene or self-crosslinking acrylic dispersion reduces dry film hardness; the PVAc stiffening agent dosage must then be re-optimized for the specific substrate and bond geometry. Equipment clean-up after crosslinked formulations should be performed immediately with warm water before film dehydration, because dried deposits resist cold-water removal and can damage doctor blades and transfer rolls.
