Dairen DA-346 Emulsão VAE

Why DA-346 Outperforms Conventional PVAc Homopolymer Dispersions in Nonwoven Wet Wipe Binders

Dairen DA-346 is a poly(vinyl acetate-co-ethylene) aqueous emulsion polymerized with a self-crosslinking functional moiety that remains dormant in the acidic storage state (pH 4.5–5.5) and activates under mild thermal curing. In air-through bonded carded webs processed at 130–150°C, the crosslinked binder network delivers wet tensile strength retention exceeding 65% after 1-hour water immersion when tested per WSP 70.1:2012, whereas conventional non-crosslinking poly(vinyl acetate) homopolymer dispersions routinely fall below 15% retention. The distinction arises from the ethylene comonomer content (typically 15–20 wt% in the copolymer backbone), which plasticizes the film internally and eliminates the need for external phthalate or benzoate plasticizers that migrate over time, stiffening the web and compromising rewet performance. The high ethylene fraction also shifts the glass transition temperature (Tg) to approximately 0°C, measured by differential scanning calorimetry at a heating rate of 10 K/min under nitrogen purge, while the crosslinking density generated during the drying train on a Fleissner or Andritz line raises the softening point above 150°C — an operational window that tolerates direct hot drum contact without blocking. On pilot-scale carding and hydroentanglement equipment operated at 100 m/min, binder add-on levels of 8–12 wt% (dry on dry fabric) yield machine-direction tensile strength of 80–120 N/5 cm (strip method, ISO 9073-3:1989), fully sufficient for personal care converting. The self-crosslinking mechanism is acid-catalyzed by residual buffered acetic acid, meaning that formulation pH must be maintained above 4.0 during storage; addition of zinc nitrate or ammonium chloride catalysts can depress the curing temperature to 120°C, though pot-life of the catalyzed bath drops to 4–6 hours at 25°C, making continuous inline metering preferable to batch recirculation.

Unlike styrene-acrylic latexes, which exhibit a steep viscosity build under high shear in roll-coating applicators due to excessive water-retention, the DA-346 emulsion maintains a near-Newtonian flow profile at shear rates up to 1000 s⁻¹, with a Brookfield LVF viscosity of 1500–3000 mPa·s (spindle 3, 20 rpm, ISO 2555:2018) and a solids content of 55.0 ± 1.0%. The low minimum film-forming temperature (MFFT) of ≤ 2°C (ISO 2115:2000) permits exhaustive film coalescence even at ambient conditions without the coalescent adulteration that raises VOC content and slows processing speed. In side-by-side trials on a Bematic pilot line at a line speed of 80 m/min, DA-346 deposited via a kiss-roll saturator exhibited 30% lower downstream odour than an internally plasticized acrylic of comparable solids, as assessed by gas chromatography–olfactometry of the finished nonwoven after 24-hour equilibration at 23°C/50% RH.

High-Speed Paper Converting and LDPE Lamination Adhesives: A Processing Window Below 5°C

Dairen DA-346 VAE emulsion is supplied as a waterborne, plasticizer-free binder with a minimum film-forming temperature of ≤ 2°C, a property that eliminates the need for fugitive coalescents in cold-weather converting plants where ambient temperatures may fall to 10°C. In paper-to-paper and paper-to-LDPE lamination on a Valmet Optigloss coater running at 180 m/min, the emulsion is applied at a coat weight of 3–5 g/m² (dry) via a three-roll transfer system. The cohesive strength of the copolymer, stemming from the main-chain ethylene blocks and pendant acetate groups, permits immediate fibre tear propagation within 20 seconds of dry contact after hot-nip lamination at 70°C.

The difference between DA-346 and predecessor VAE grades such as DA-102 becomes evident under alkaline buffer conditions prevalent in recycled board. The DA-346 binder’s built-in carboxylic acid functionality reacts with surface aluminium ions released from kaolin coatings or aluminium sulphate retention aids, forming ionic crosslinks that maintain a 180° peel adhesion value exceeding 2.5 N/cm (ASTM D1876-08) after 7-day conditioning at 40°C/85% RH. In contrast, standard VAE lacking ionic functionality lose peel strength by 40–50% under identical hydrothermal ageing. The emulsion particle size, measured by dynamic light scattering (Malvern Zetasizer) as 0.8–1.2 µm volume mean diameter, permits direct flexographic impression without excessive pinholing when combined with a carboxylated styrene-butadiene cobinder at a blend ratio of 80:20 by dry weight.

Comparative binder property matrix: Dairen DA-346 versus typical VAE and acrylic emulsions for nonwoven

Property	DA-346	Standard VAE (plasticized)	Styrene-acrylic (self-crosslinking)
Solids content (%)	55.0 ± 1.0	50–53	45–48
pH	4.5–5.5	4.0–5.0	7.5–8.5
MFFT (°C, ISO 2115)	≤ 2	5–10	0–5
Wet tensile retention (nonwoven, %, WSP 70.1)	> 65	10–20	50–60
VOC content (g/L, EPA Method 24)	<10	30–50	15–25
Heat-seal activation temperature (°C)	60–70	80–100	100–120

Migration Kinetics in Polymer-Modified Cementitious Systems

The ethylene content of DA-346 VAE emulsion functions as a permanent internal plasticizer, eliminating the exudation of low-molecular-weight plasticizers that stains porous substrates and reduces intercoat adhesion in tile adhesives formulated under EN 12004:2017. When compounded into a Portland cement-based repair mortar at a polymer-to-cement ratio (p/c) of 0.10–0.15, the latex co-mingles with the hydration products and forms a continuous polymer network within the capillary pore structure after the cement matrix sets. Flexural strength increases by 40–60% relative to unmodified mortar after 28 days of water immersion (EN 196-1:2016), while compressive strength may drop by 5–10% because the pliable polymer domains reduce the elastic modulus of the composite.

Unlike ethylene-vinyl acetate (EVA) redispersible powders that require complete drying before cement contact, the liquid DA-346 emulsion can be added directly to the mixing water without pre-dispersion if the water-to-cement ratio is raised by 0.02–0.03 to compensate. The carboxylate stabilisation system interacts with Ca²⁺ ions released during initial hydration, producing a controlled flocculation that provides anti-washout properties when screeding vertical surfaces with layer thicknesses up to 10 mm in a single pass. Differences from acrylic-modified cementitious patches become apparent in open time: DA-346-modified thin-set mortars retain a trowel-applicable consistency for 25–30 minutes at 23°C/50% RH, outlasting a styrene-acrylic of comparable film hardness by about 5–8 minutes because the partially hydrolysed acetate-polyethylene film absorbs less water from the fresh mortar surface.

Compatibility with calcium aluminate cement (CAC) accelerates setting, and addition levels above 15 wt% (polymer dry on cement) can retard the C₃A hydration by more than 2 hours if the emulsion is not pre-neutralised to pH 6.5–7.0 with dilute NaOH. No chloride-containing additives are introduced during manufacture, meaning the total chloride ion content of the emulsion is below 0.05 wt% (EN 15183:2006), preserving the passivation of embedded steel reinforcement under carbonated concrete conditions.

Regulatory conformance matrix for Dairen DA-346 VAE emulsion

Regulation or standard	Specific requirement	Compliance status
FDA 21 CFR 175.105	Adhesives for indirect food contact (dry, aqueous, fatty)	Compliant at up to 95 wt% of adhesive solids
FDA 21 CFR 176.170	Components of paper and paperboard in contact with aqueous and fatty foods	Compliant
BfR XXXVI	Paper and board for food contact	Non-detectable residual monomer (<0.1 mg/kg)
EN 71-3:2019	Migration of certain elements from toys	All limits met
REACH (EC 1907/2006)	SVHC content, Annex XVII restrictions	No SVHC> 0.1 wt%

When a Formulation Requires Plasticizer-Free Softness Without Sacrificing Heat Resistance

In textile pigment printing, DA-346 deposits a low-Tg film that cures during fixation at 150–160°C into a thermoset network, giving a soft handle on cellulose and polyester/cotton blends without the stiffening characteristic of acrylic printing binders. Formulators who have attempted plasticized PVAc pastes observe crockfastness ratings of only 2–3 (grey scale) after 5 wash cycles per ISO 105-C06:2010, whereas DA-346-based clear prints reach 4–5 under identical testing using 3% crosslinker addition (a water-dispersible blocked isocyanate). This difference arises because the internal ethylene segments do not migrate; the external plasticizer in PVAc systems leaches during laundering, leaving microvoids that abrade under rubbing.

Continuous rotary screen printing on a Stork FM-3 press operating at 40 m/min with 125 mesh screens calls for a paste viscosity of 20–25 Pa·s at 1 s⁻¹ shear. DA-346 alone at its delivery solids exhibits a lower viscosity plateau, necessitating the addition of a polyacrylate thickener until the system reaches 22 Pa·s. The resulting pseudoplastic flow profile ensures clean penetration into the fibre bundle yet prevents lateral wicking that blurs fine-line edges defined by high-engraving screens. For white spirit-free systems, a water-miscible silicone antifoam at 0.05–0.1 wt% of the paste weight suppresses microfoam that would otherwise crater the film and compromise coverage under ISO 105-A02:1993 colour change tests.

In spray-applied flock adhesives dispensed through a Binks 460 air-assisted airless gun with a tip orifice of 0.013 inch, the emulsion’s pseudoplasticity prevents sag on vertical polyester velour even at wet film thicknesses of 200 µm. The dry film exhibits a Kofler heat block tack temperature of 60°C — useful for heat lamination of backing films — and yet the ultimate cohesive strength of the film exceeds 2.5 MPa when measured at 23°C under ASTM D638-14 (type IV die, crosshead speed 50 mm/min). This combination of rapid heat sealability and high internal strength in a single component distinguishes DA-346 from two-component isocyanate-crosslinked polyurethane dispersions that offer greater film toughness but require a pot-life clock and introduce industrial hygiene concerns regarding free isocyanates.