| HS Code | 174166 |
| Appearance | Translucent liquid |
| Solid Content | 50 ± 1% |
| Viscosity | 3000-5000 mPa·s (Brookfield RVT, spindle 4, 20 rpm, 25°C) |
| Ph | 4.5-5.5 |
| Glass Transition Temperature | 10°C |
| Minimum Film Forming Temperature | 5°C |
| Light Transmittance | ≥92% |
| Haze | ≤3% |
| Tensile Strength | 15 MPa |
| Elongation At Break | 300% |
| Adhesion Strength | 1.5 N/mm² (wood-to-wood) |
| Water Resistance | Good (24h water immersion bond retention >70%) |
| Freeze Thaw Stability | 5 cycles |
| Weight Average Molecular Weight | 150,000 g/mol |
As an accredited High-Transparency Acrylic-Modified PVAc factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 25 kg sealed, light-protective drums with tamper-evident lids, ensuring high transparency and stable acrylic-modified PVAc emulsion. |
| Container Loading (20′ FCL) | 20′ FCL: High-Transparency Acrylic-Modified PVAc loaded in sealed drums/IBCs, securely palletized, ventilated, and protected from moisture. |
| Shipping | Ship as non-hazardous aqueous emulsion in sealed drums or IBC totes. Protect from freezing, extreme heat, and direct sunlight. Store between 5–35°C with containers upright. Ensure proper ventilation and secure loading to prevent leakage. Avoid skin contact; use spill containment during transit. |
| Storage | Store High-Transparency Acrylic-Modified PVAc in a sealed, original container. Keep in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and open flames. Avoid freezing and temperatures above 30°C. Protect from moisture. Use within the manufacturer’s stated shelf life, ensuring adequate ventilation and safe handling practices. |
| Shelf Life | Typical shelf life is 12 months when stored sealed in original container, away from freezing and direct sunlight, moderate temperatures. |
On a high-gloss wood veneer laminating line producing kitchen door panels and bathroom vanity fronts, the adhesive bondline is visible through open-pored ash, maple, and birch at dry film thicknesses of 80–120 µm after pressing. Unmodified PVAc homopolymer dispersions produce a milky film in this range because poly(vinyl alcohol) protective colloid remains as discrete scattering domains after coalescence. High-transparency acrylic-modified PVAc containing 20–35 wt% acrylic ester in the polymer phase reduces these scattering domains and yields a dry film with a refractive index between 1.47 and 1.49, close to the cell-wall index of maple at 1.47–1.48. The adhesive is roller-coated at 100–120 g/m² wet onto the veneer backer or HDF, assembled within 8–12 min at 20–25°C and 55–65% RH, and membrane-pressed at 0.8–1.2 N/mm² for 10–20 min. For D3 non-structural interior applications, the cured bond is tested according to EN 204 on beech lap-shear specimens; the classification requires retention of shear strength after defined water immersion cycles, not merely a high dry shear value. Field observations on membrane-press lines indicate that batch-to-batch viscosity drift of ±5,000 mPa·s at 20°C shifts the applied coat weight by up to 12 g/m² on a comma-roll coater; closed-loop viscosity control with an inline rotary viscometer is therefore used where bondline clarity is specified. High-tannin substrates such as oak require stainless-steel or ceramic contact parts because residual iron from carbon steel rollers can form a blue-black tannate complex that becomes visible through the transparent film. A significant operational boundary is board moisture: HDF moisture above 10% delays coalescence and can raise final haze by retaining water in the film, while board temperatures below 15°C extend the minimum press time unless the adhesive is formulated with a stated low minimum film forming temperature.
Transparent windowed cartons consisting of 350 g/m² SBS board and 20 µm corona-treated BOPP film are manufactured on a wet-bond laminator with a 900 mm wide, 50 lines/cm gravure cylinder and a chambered doctor blade. The adhesive is applied at 6–10 g/m² wet and immediately nipped against the board, then dried through three zones set at 70°C, 85°C, and 90°C. The dried adhesive layer is measured for haze and total luminous transmittance according to ASTM D1003. Haze above 7% at 50 µm dry film thickness is generally linked to three mechanisms: retained water from incomplete nip drying, deposition of low-molecular-weight acrylic oligomer at the film interface, and microphase separation of the protective colloid. Acrylic-modified grades containing 20–30% n-butyl acrylate or 2-ethylhexyl acrylate in the polymer backbone exhibit less free protective colloid because the acrylic segment itself contributes to particle stabilization, though published data for this specific configuration is limited. For food-contact windowed cartons, the adhesive is normally applied on the inner side of the window film and must comply with FDA 21 CFR 175.105 as a packaging adhesive. The regulation does not assign a single migration limit but requires that the substance be used only in an amount necessary to produce the intended effect and that the finished package not render food unsafe. Converters exporting to Europe must also screen the finished laminate against EU Regulation 10/2011; the adhesive itself is not a finished plastic material, so compliance must be demonstrated on the complete windowed carton. Relative humidity above 70% at the coating station causes skinning in the gravure cells and should be controlled by local air-conditioning. The BOPP film must be corona-treated to a wetting tension of 38–40 mN/m because PVAc dispersions will not wet untreated polypropylene at lower surface energy without an adhesion promoter.
In perfect binding at 12,000 cycles/h, the spine primer is the first aqueous layer applied to the milled signature. Transparent acrylic-modified PVAc has a refractive index close to that of coated and uncoated paper, which prevents visible adhesive shine-through on thin bible stock and on bright white litho papers. The primer is applied at 0.2–0.4 mm wet thickness with a spine wheel whose doctor gap is controlled to ±0.05 mm; too little primer leaves dry paper on the spine, while too much produces squeeze-out beyond the hinge line. The coating is then dried with hot air at 80–100°C for 2–5 s before the side glue and cover are applied. The pH of the dispersion is maintained between 5.0 and 6.5 in acrylic-modified grades because unbuffered acidic adhesive can migrate into the paper and induce cellulose chain scission in acid-sensitive stock. Blocking resistance is evaluated under 40°C and 80% RH with stacked printed covers; ASTM D907 defines blocking in terminology, but the pass/fail criterion is normally an observed ink transfer at a specified compression load. Homopolymer PVAc has high initial grasp but is more prone to cold flow in warehouse stacks at elevated temperature; acrylic modification reduces cold flow at equal viscosity without requiring plasticizer that would later volatilize and yellow the transparent band. Heavily coated art paper with UV-cured ink coverage above 80% may require an adhesion-promoting primer because the aqueous adhesive cannot penetrate the cross-linked ink surface; standard high-transparency PVAc grades may remain wet and transfer to adjacent signatures in such cases.
Inline carton gluing of clay-coated SBS at 180,000 cartons per 12 h shift compresses bondline formation, fiber wet-out, and green strength build into less than 2 s. The adhesive is pumped through a high-pressure fluid manifold to needle nozzles of 0.3–0.5 mm inside diameter at 2.5–4.0 bar; nozzle tips are positioned 1–2 mm above the board surface. High-transparency acrylic-modified PVAc is selected when the carton has a clear PET window, a cut-out section, or a UV-cured varnish that must not show a white adhesive line. Viscosity at 25°C is controlled to 15,000–25,000 mPa·s per ISO 2555:2018, with a thixotropic index of 0.35–0.50 between 10 s⁻¹ and 100 s⁻¹; lower thixotropy causes stringing from the nozzle, while higher thixotropy reduces wet-out on aqueous-coated board. Foaming in the adhesive return line is a common production failure because the piston pump and recirculation loop introduce air; a mineral-oil defoamer at 0.05–0.15% by weight is used, but excess defoamer produces visible fisheyes in the transparent bondline. Board substrates with UV varnish require a minimum surface energy of 38–40 mN/m; inline corona or plasma treatment is used when the varnish has a water contact angle above 78°. Adhesion is verified by ASTM D6862-04 90° peel on clay-coated SBS; values below 1.0 N/mm after 24 h conditioning indicate insufficient bond for high-speed erecting. Dried adhesive from nozzle tips is softened with warm water at 30–40°C; once fully dried and partially cross-linked under radiant heat, PVAc films are not readily soluble in alkaline detergents, and a 5% acetic acid solution may be required to dissolve deposits. Stop times longer than 10 min require a programmed water mist purge to prevent nozzle plugging.
Profile wrapping of 0.15–0.25 mm printed PVC film onto MDF or HDF profiles is conducted at line speeds of 10–30 m/min. The adhesive is roll-coated onto the profile edge at 60–100 g/m² and then activated by a combination of hot-air jets at 55–70°C and press rolls at 1–3 bar. Acrylic modification contributes to wetting of the PVC surface because the acrylic ester segments lower the interfacial tension relative to pure PVAc, but the principal long-term failure is not initial adhesion; it is plasticizer migration. A PVC film containing 20% or more DINCH or dioctyl terephthalate can plasticize the adhesive layer, reduce its glass transition temperature, and produce creep at service temperatures above 60°C. Peel strength measured by ASTM D1876-24 can fall from an initial 2.0–3.0 N/mm to below 0.8 N/mm after 7 days at 70°C when no adhesion-promoting barrier is present. A two-component modification with 5 wt% water-dispersible aliphatic isocyanate hardener raises water resistance and plasticizer resistance, but the pot life drops to 3–4 h at 25°C. Mixing must be performed in a separate dosing unit with continuous circulation and automated purging every 30 min on line stops to prevent gelled deposits in the roller nip. Bondline clarity is also affected by chalk filler: if a transparent edge is specified, filler addition must be avoided because inorganic particles with refractive index above 1.55 scatter light and create a milky band at the film edge. Published data for this specific configuration is limited because PVC film formulations and plasticizer packages vary significantly by supplier.
The operative constraint in a chilled case-sealing bay at 8°C is not open time but coalescence. Unmodified PVAc homopolymer dispersions with a minimum film forming temperature of 10–14°C do not form a continuous transparent film on board surfaces below 15°C unless the line is equipped with post-heating. Acrylic-modified PVAc grades can be formulated to an MFFT of 0–3°C, permitting clear bondlines on light-weight corrugated board and clear PET cartons in cold storage. At 5°C, viscosity can increase from 20,000 mPa·s to 60,000 mPa·s or higher; the glue-head pressure must be temperature-compensated, and needle valves should be diameter-checked because cold lean cut-off becomes slower. Freeze-thaw stability is a separate boundary. Many PVAc dispersions are not freeze-thaw stable and will coagulate after storage below -5°C; ISO 1147:1995 five-cycle freeze-thaw testing is not passed by standard grades unless the formulation contains specific protective colloid blends. A case glued at 8°C may pass initial compression, but if the film was formed below the MFFT, the bondline will show white microcracks and lose flexural strength. Rewarming to 35°C for 20 s can clarify the film without restoring full mechanical strength because the coalescence defects formed during film formation are permanent.
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High-transparency acrylic-modified poly(vinyl acetate), reference grade HT-ACPVAc 440, is a waterborne vinyl acetate–acrylic ester copolymer dispersion produced by semicontinuous emulsion polymerization. The acrylic comonomer is inserted randomly into the vinyl acetate backbone during the main monomer feed, not post-blended as a separate acrylic latex, which distinguishes the product from physical mixtures of PVAc and acrylic dispersions. The product is supplied at 54–56% non-volatile content with a Brookfield RVT viscosity of 4,000–8,000 mPa·s at 23 °C using spindle #4 at 20 rpm. A cast film cured for 24 h at 23 °C and 50% relative humidity shows total luminous transmittance of ≥91% at 550 nm when measured according to ISO 13468-2 on a 1.0 mm wet film. The minimum film-forming temperature is 3–5 °C, measured by ISO 2115; for a standard homopolymer PVAc dispersion of similar solids, MFFT typically remains at 15–18 °C. Dried polymer glass transition is 10–14 °C by ISO 11357-2 at 10 K/min. The grade is used for clear laminating adhesives, paper-to-film windowing, and assembly of transparent folding cartons where the dried film must not obscure print.
The primary difference is internal plasticization through short-chain acrylic ester branches. Homopolymer PVAc requires external plasticizer such as diisobutyl phthalate or triacetin to reduce minimum film-forming temperature below 10 °C; those plasticizers migrate over time, increasing haze and weakening adhesion under flexural stress. In the acrylic-modified grade, the comonomer reduces chain packing and lowers MFFT without mobile plasticizer. This produces better retention of optical clarity after accelerated aging. Haze after 500 h at 60 °C dry heat is typically 2.0–3.5% for HT-ACPVAc 440, while plasticized homopolymer films often exceed 8% under the same conditions. Adhesion to cellulose remains comparable because the vinyl acetate repeat unit still provides hydrogen bonding to paper, board, and wood hydroxy groups. The acrylic component also reduces the tendency for acetic acid release during alkaline hydrolysis. However, water resistance remains below that of a pure acrylic emulsion; immersion in 23 °C water for 24 h produces slight blushing and a tensile strength retention of approximately 60–70% when tested by ASTM D882. Unlike a physical blend, the copolymer shows a single glass transition rather than two transitions, measurable by modulated DSC per ISO 11357-2. This single-phase morphology is required for transparent films; phase-separated blends scatter light at domain boundaries.
Typical release specification and batch quality limits for HT-ACPVAc 440 are shown below. Values are drawn from the manufacturer’s certificate of analysis; where a downstream application requires a narrower band, a further post-dilution or pH adjustment is made in the mixing vessel before coating.
| Property | Specification range | Test method |
|---|---|---|
| Non-volatile content | 54–56% | ISO 3251 |
| pH at 23 °C | 4.0–5.0 | ISO 976 |
| Brookfield RVT viscosity | 4,000–8,000 mPa·s | ISO 2555 |
| Density at 23 °C | 1.07–1.09 g/cm3 | ISO 2811-1 |
| Minimum film-forming temperature | 3–5 °C | ISO 2115 |
| Residual vinyl acetate monomer | ≤0.1% | ISO 13741-1 |
| Grit on 40 µm sieve | ≤200 mg/kg | DIN EN ISO 4576 |
| Film transmittance at 550 nm | ≥91% | ISO 13468-2 |
Batch-to-batch variation in pH is typically held within ±0.2. Drift above 5.5 during storage is associated with hydrolysis of acetate groups; drums should be sealed and stored at 5–30 °C. Published data for the specific combination of HT-ACPVAc 440 with high-clarity cast polypropylene film is limited; finished laminate haze should be qualified under ASTM D1003 and ISO 14782. For food-contact laminates, finished-formulation compliance with FDA 21 CFR 175.105 and EU 10/2011 must be verified on the complete adhesive, including defoamer and wetting agents; the base dispersion itself is not a food-contact approval.
Optical clarity in the dried bond line is obtained when the adhesive refractive index is close to that of the substrate and when particle boundaries coalesce completely. The dried HT-ACPVAc 440 film has a refractive index of 1.465–1.470 at 23 °C, which is lower than unmodified PVAc and closer to the 1.47–1.49 range of many acrylic-coated papers and polyester films. Drying conditions influence clarity more than initial dispersion appearance. If the wet layer is dried above 60 °C, surface skinning traps water and creates microvoids that scatter light. A two-zone tunnel set to 45 °C for 120 s and 55 °C for 90 s is used on a roll-to-roll line with 30–40 m/min web speed. Under these conditions, the dried adhesive layer at 8–12 g/m2 dry coat weight exhibits haze of 1.5–3.0% per ASTM D1003. For reverse-printed film lamination, the adhesive is applied by smooth-roll coater to the printed side at 4–6 g/m2 dry coat weight and nipped to paper at 60–70 °C. The product does not require a post-cure crosslinker for clear-window carton assembly, but water resistance is limited; if the carton passes through a dishwasher or prolonged condensation cycle, a separate polyisocyanate hardener at 2–3 wt% of dispersion is required and pot life drops to 4–6 h.
The copolymer composition of HT-ACPVAc 440 is set to maintain the acrylic comonomer below 15 wt% of polymer solids. This threshold preserves the cellulosic adhesion and setting speed of PVAc while limiting the mobility of low-molecular-weight ester segments. Formulations with less than 10 wt% acrylic show an MFFT of 8–12 °C, which is still too high for unheated winter application on corrugated board. Raising the comonomer to 12–14 wt% shifts MFFT to 3–5 °C and increases elongation at break to 280–350% by ASTM D638-14 on a Type IV die. Above 18 wt%, the surface becomes more hydrophobic, and wetting on uncoated recycled linerboard drops below 42 dyn/cm, as measured by ASTM D2578. This creates retraction at pattern edges on high-speed gluers. For the reference grade, wetting on kraft linerboard is typically 44–46 dyn/cm. The balance point is therefore narrow; blending with defoamer or wetting agent must be verified on the target substrate because silicone-based defoamers reduce dyne level and produce fisheyes. Published data for this specific adhesive on supercalendered kraft release liner is limited; application trials should include wetting checks per ASTM D2578 before line speed is fixed.
On high-speed folding-carton lines and window-patching machines, HT-ACPVAc 440 is transferred from open supply tanks by diaphragm pumps with stainless steel wetted parts; cast iron and carbon steel should be avoided because the acidic pH of 4.0–5.0 promotes corrosion at welds. Shear viscosity at 23 °C measured by cone-and-plate rheometry per ISO 3219 is 9,000–11,000 mPa·s at 1 s−1 and 800–1,200 mPa·s at 100 s−1. The low high-shear viscosity allows transfer through fine glue nozzles of 0.3–0.5 mm without stringing when the nozzle tip is heated to 35–40 °C. On a 24-station window patching wheel operating at 12,000 cycles/h, wet deposition is typically 25–40 g/m2 on polyester film to paperboard. Open pot stability is 8–10 h when the surrounding air is held at 50% RH to slow skinning. If pH rises above 6.0 due to alkaline board dust, viscosity may climb by 30–50% and the dispersion can form grit; buffering with 0.1–0.2 wt% trisodium citrate on total dispersion counters this drift. Amine-based defoamers and ammonia-based pH adjusters should not be used, because volatile amines destabilize the anionic emulsifier package and produce coagulum on doctor blades within 30–60 min.
Curtain coating of the dispersion onto clay-coated paperboard requires a viscosity below 1,500 mPa·s at the curtain lip. The product is therefore diluted with deionized water by 5–10% to a Brookfield RVT viscosity of 1,200–1,800 mPa·s. The curtain stability window is 35–45 °C; below 35 °C the curtain contracts, and above 45 °C evaporation at the lip causes stream break-up. In roll-to-roll lamination of reverse-printed BOPP to paper, corona pretreatment of the film to 42–44 dyn/cm is required, with a wet laydown of 5–8 g/m2 dry adhesive. Nip temperature is set at 65–75 °C, and the laminate is left under tension for 24 h before die-cutting. Edge-gluing of book blocks with the product at ambient temperature shows an initial tack time of 20–40 s on uncoated paper, allowing repositioning. When polyvinyl alcohol is added at 2–5 wt% as a rheology modifier, tack time shortens to 10–20 s but film clarity decreases slightly. The dried film remains repulpable under standard paper-recycling conditions. Adhesion to cellulose is tested by DIN EN 204; the uncrosslinked film meets D2 classification, and D3 classification can be achieved only with a suitable crosslinker and specific substrate pairing.
Comparative values in the following table are typical ranges from publicly available technical data sheets for waterborne adhesive grades. Direct formulation comparisons require adjustment to equal solids and film thickness.
| Property | HT-ACPVAc 440 | Homopolymer PVAc | Acrylic emulsion |
|---|---|---|---|
| Total luminous transmittance at 550 nm | ≥91% (ISO 13468-2) | 84–88% | 88–92% |
| Minimum film-forming temperature | 3–5 °C (ISO 2115) | 15–18 °C | 0–5 °C |
| Tensile retention after 24 h water immersion | 60–70% (ASTM D882) | 40–50% | 80–90% |
| Wet adhesion to kraft linerboard | High (DIN EN 204 D2) | High (DIN EN 204 D2) | Moderate |
| Acetic acid release during thermal aging at 80 °C | Low | Moderate-to-high | Very low |
The operational boundary for HT-ACPVAc 440 is set by pH and freeze-thaw stability. The dispersion must not be allowed to freeze; one freeze-thaw cycle at −5 °C causes irreversible coagulation because the protective colloid cannot rehydrate. For use on nonporous plastic films, the maximum dry coat weight without forced air is 12 g/m2; above this, residual water under the skin produces blisters and haze.
