Dairen DA-144 Emulsão VAE

A carboxylated vinyl acetate-ethylene (VAE) copolymer dispersion designed for water-based adhesive and coating systems that demand flexibility without external plasticizer, Dairen DA-144 exhibits a minimum film-forming temperature (MFFT) of 0°C (ISO 2115) and a glass transition temperature (Tg) near -5°C by differential scanning calorimetry (heating rate 10 K/min, ISO 11357-2). The dispersion contains a polyvinyl alcohol (PVOH) protective colloid and a built-in carboxyl functionality, which together contribute to high wet tack and strong adhesion to cellulosic and non-porous substrates alike. Table 1 lists the core specification envelope as supplied.

Table 1 — Typical Physical Properties of DA-144 (Lot-Averaged Values)

Property	Nominal Range	Test Method
Solids content	53.0 ±1.0 %	ISO 3251 (125 °C, 1 h)
pH	4.0 – 5.5	ASTM E70
Brookfield RVT viscosity (20 rpm, 25 °C)	1 500 – 3 500 mPa·s	ISO 2555
Density at 20 °C	1.06 – 1.08 g/cm³	ISO 2811-2
Particle size (d50)	1.0 – 1.5 µm	Laser diffraction (Malvern Mastersizer)
Surface tension	38 – 42 mN/m	ISO 1409 (Du Noüy ring)
Residual vinyl acetate monomer	< 0.5 %	ISO 13741-1

The emulsion’s high ethylene content — typically 16 – 20 wt% of total polymer — lowers both the Tg and the elastic modulus of the dried film, generating a flexibility that persists down to sub-zero application temperatures. In direct contrast to polyvinyl acetate homopolymers, which exhibit a Tg above 30 °C and require substantial external coalescent to form a coherent film, DA‑144 coalesces without organic solvents under ambient conditions, an advantage that becomes especially critical in indoor environments subject to low-emission standards.

When Plasticizer-Free Film Formation Must Reach 0 °C

Film integrity of DA‑144 on low-porosity substrates such as corona-treated BOPP or aluminium foil is dictated by the relationship between MFFT and the application temperature. Below 5 °C substrate temperature, the rate of polymer particle deformation slows sufficiently that surface cracking can appear unless the drying profile is adjusted. In practice, pre-heating the substrate to 40 °C via infrared panels immediately upstream of the coating station eliminates micro-crazing, confirmed by optical microscopy at 50× magnification and by a tape snap test (ISO 2409 adhesion Class 0). Where forced drying is unavailable, a coalescent surrogate such as 3 wt% tripropylene glycol monomethyl ether (TPM) on wet weight can shift the MFFT below -5 °C, although this addition is seldom required for adhesive laminations destined for ambient-temperature use. In automatic edgebanding lines that replace a traditional PUR hot-melt cartridge with a water-based contact adhesive, the emulsion’s combination of rapid mechanical set and shear-stable viscosity prevents the spring-back of 2 mm ABS edging at line speeds up to 15 m/min. The application head, a precision roller coater delivering 35 g/m² wet film weight, operates continuously for 8 h without filter blinding when a 200 µm mesh inline filter is used. Foaming, which can become pronounced at line speeds beyond 250 m/min, is suppressed by the addition of a polyether siloxane defoamer at 0.05 wt%; dynamic foam height measured per ASTM D3601 then remains below 5 mm after 10 min recirculation in a gear pump with a back-pressure of 1.5 bar. This operating window directly addresses the limitations observed with low-ethylene VAE grades, whose higher surface tension and slower set speed frequently cause edge lift-off below 12 m/min.

High-Shear Circulation Pumping and Nozzle Clogging Resistance

Routine processing of DA‑144 through air-operated diaphragm pumps or progressing-cavity pumps exposes the dispersion to shear rates exceeding 10 000 s⁻¹ at constriction points. Mechanical stability is a critical differentiator from surfactant-stabilized acrylic dispersions: after 30 min recirculation through a Netzsch Nemo pump fitted with a 6 bar bypass loop and a 0.5 mm orifice, viscosity loss measured per ISO 2555 remains below 10 %, and coagulum collected on a 45 µm sieve (ISO 4576) does not exceed 50 mg per kg of emulsion. By comparison, an equivalent-solids styrene-acrylic dispersion tested under identical conditions shows a viscosity decay of more than 25 % with visible grit. Spray application through airless nozzles (e.g., Graco RAC 5 tip, 0.33 mm orifice) can be sustained for 4 h continuous operation without tip clogging only if the feed pressure is maintained between 80 and 120 bar. Below 70 bar, droplet atomisation becomes incomplete, leading to an orange-peel film appearance; above 130 bar, shear-induced destabilisation produces micro-gels that accumulate on the nozzle seat. These thresholds were established on a Graco Merkur ES pump assembly with a 15 L supply hopper and a pulsation damper set to 85 % of system pressure. Compatibility with external crosslinkers expands the thermal resistance of DA‑144 films. Addition of 1.5 wt% of a water-dispersible polyfunctional aziridine (e.g., trimethylolpropane tris(2-methyl-1-aziridinepropionate)) before application raises the heat resistance temperature from 85 °C to beyond 120 °C as determined by a shear-loaded lap-shear test (DIN EN 14257, 500 g load, 30 min hold). Pot life of the catalysed blend, however, drops to 3 – 4 h at 25 °C; the viscosity doubles before gelation commences, mandating precise on-line metering when working with automated ribbon coaters. Published data for isocyanate-based crosslinkers in this specific emulsion is limited, and preliminary bench trials with hexamethylene diisocyanate trimer at 2 wt% have yielded erratic adhesive performance, likely due to premature reaction with the hydroxyl groups of the PVOH colloid.

Why Does DA-144 Outperform Low-Ethylene VAE on Corona-Treated Polypropylene Film?

The elevated ethylene content raises the surface energy of the dried adhesive layer above that obtainable with VAE emulsions containing less than 12 % ethylene. Contact angle measurements on 50 µm thick films cast on glass and dried for 7 days at 23 °C, 50 % RH yield a water contact angle of 68 ±2° (sessile drop method, ISO 19403-2), versus 78 ±3° for a low-ethylene VAE. When laminated to corona-treated PP film (surface energy 42 mN/m, measured by Dyne test pens per ISO 8296), T-peel adhesion under 100 mm/min (ISO 11339) reaches 2.8 N/15 mm with substrate failure in the PP, whereas the low-ethylene version averages 1.2 N/15 mm with adhesive failure. The carboxyl groups further contribute to specific interactions with the oxygen-containing species generated on the treated PP surface, producing peel improvements of an additional 20 % relative to a non‑carboxylated VAE with an equivalent ethylene content. In wet lamination of polyester film to paper, the open time window achievable with DA‑144 is substantially wider than that of a standard PVAc homopolymer. At 23 °C and 50 % RH, a machine-applied film of 30 g/m² wet weight on 80 g/m² coated paper remains tacky for 12 min, sufficient to accommodate the staggered threading paths of a multi‑station laminator operating at 60 m/min. A D3 classification bond (EN 204, storage condition 7 days in standard atmosphere) is reliably attained with a minimum press time of 45 min at 0.7 MPa. To eliminate the risk of over‑penetration into low‑basis‑weight papers, a viscosity modifier such as hydrophobically modified alkali‑swellable emulsion (HASE) thickener is typically dosed at 0.2 – 0.5 wt%, raising the Brookfield viscosity to 5 000 – 8 000 mPa·s. The colloidal protective system based on partially hydrolysed PVOH also imparts a characteristic water sensitivity that must be considered when the adhesive joint is subject to prolonged immersion. After 4 h immersion in water at 23 °C (EN 204, D2 condition), specimens bonded with neat DA‑144 retain approximately 60 % of dry strength. Where full D4 durability is targeted, post‑addition of 5 wt% of a polymeric isocyanate emulsifiable in water (pMDI) elevates wet strength retention above 85 % but shortens pot life to 90 min, necessitating static mixer application heads. The emulsion carries explicit forbearance toward ionic disruption. Mixing DA‑144 with an undispersed calcium carbonate slurry leads to cation‑induced coagulation within 30 s due to the carboxyl groups reacting with Ca²⁺; pre‑dispersing the filler with a sodium polyacrylate dispersant at a minimum addition of 0.3 % on filler weight eliminates flocculation and produces a smooth, pourable compound. Similarly, amine-containing additives that raise the pH above 8.5 can trigger crosslinking of the carboxyl functionalities, increasing the minimum film-forming temperature by 3–5 °C and reducing the wet tack. Therefore, all formulation work is performed with the admixture pH held within 4.5–7.0. Differences between DA‑144 and adjacent VAE grades primarily centre on ethylene ratio and functional group density. Dairen DA‑142, for instance, is formulated with a lower ethylene content (≈10 %), yielding a Tg near 5 °C and an MFFT of 6 °C — values that complicate film formation below 10 °C without coalescent. DA‑144 also delivers roughly 30 % higher peel adhesion to LDPE than DA‑142 at the same film weight. In contrast, DA‑145 incorporates a higher solids content (58 %) and a modified carboxylation level optimised for high-speed case-sealing adhesives, but exhibits a narrower adhesion spectrum on polymeric films. Table 2 distils these distinctions through mechanical property data generated on identical test assemblies.

Table 2 — Comparative Performance on Corona-Treated PET Film (30 g/m² dry; bonding pressure 1 bar, 23 °C/50 % RH, 24 h cure)

Property	DA-144	PVAc Homopolymer	Low-Ethylene VAE
T-Peel strength (ISO 11339)	3.2 N/15mm	0.8 N/15mm	1.8 N/15mm
Heat resistance temperature (DIN EN 14257)	85 °C	55 °C	70 °C
Elastic recovery (ISO 527-3, 100 % strain)	62 %	18 %	45 %
Film elongation at break (ISO 527-3)	520 %	35 %	310 %

Emission compliance underpins the suitability of DA‑144 for building products and packaging. The product meets the EC1 Plus standard of GEV‑Emicode under test chamber conditions (ISO 16000‑9, 28 days) with a TVOC after 3 days below 500 µg/m³. According to the manufacturer’s declaration, the formulation is free of alkylphenol ethoxylates and meets the criteria of REACH Regulation (EC) No 1907/2006 Annex XVII entries relevant to vinyl acetate. When used as an adhesive component in food packaging, DA‑144 can be formulated to comply with FDA 21 CFR 175.105 and the BfR XIV recommendation, provided any co‑binders or additives are likewise positively listed. Moisture sensitivity of the PVOH-stabilised film remains an inherent boundary condition. In permanently humid environments above 85 % RH at 23 °C, the tensile strength of an unmodified DA‑144 film decreases by approximately 40 % within 24 h (ISO 527-3, film conditioned at relevant humidity). For such exposure, external crosslinking or blending with a hydrophobic acrylic dispersion at substitution ratios of 20–30 wt% has been adopted on production lines to stabilise mechanical integrity. These practices are reported in equipment logs for roller-coater lines processing laminated furniture panels destined for tropical climates, where an in‑house cyclic humidity test (24 h at 90 % RH /40 °C alternating with 24 h at 40 % RH /23 °C) is used to qualify each batch.