DA-101: A Low-Odour VA/E Copolymer for Formulated Adhesives
DA-101 is an aqueous, surfactant-stabilised dispersion of vinyl acetate–ethylene (VAE) copolymer. The product is supplied as a milky-white liquid with a solids content of
54–56% by weight, a pH in the range
4.0–5.5, and a Brookfield viscosity (spindle 3,
20 rpm,
25 °C) of
1500–4000 mPa·s. The minimum film-forming temperature (MFFT) is below
0 °C, a characteristic conferred by the incorporation of ethylene segments that internally plasticise the copolymer backbone, eliminating the need for external coalescing solvents in many ambient-cure formulations. Residual vinyl acetate monomer content is controlled to
<500 ppm, and the product does not contain alkylphenol ethoxylate (APEO) surfactants, conforming to EU Directive
2003/53/EC. The emulsion is preserved against microbial spoilage with a mixed isothiazolinone-based biocide system active at
<15 ppm total active substance.
In paper and packaging converting plants, the absence of volatile organic coalescents in DA-101 allows lamination lines to operate without forced exhaust extraction at the adhesive application station—provided room air exchange meets a baseline of
2 air changes per hour—reducing energy consumption for make-up air heating. On high-speed case-sealing equipment running at
60–120 cartons/min, the emulsion’s rapid wet tack development, measured as a loop tack value of
≥2.5 N/25 mm on clay-coated board (FINAT
FTM 9), prevents spring-back of scored flaps before the compression belt dwell time expires. Pasteurised-edge carton bonding, where adhesive is applied to a folded seam exposed to
80–90 °C hot air for
2–3 s, does not induce skin-over or charring at the nozzle, a failure mode frequently observed with fully hydrolysed PVAc homopolymer dispersions at comparable solids.
Typical physical and compositional properties of DA-101
| Property | Value | Test method |
|---|
| Solids content | 54–56 wt% | ISO 3251:2019 |
| pH | 4.0–5.5 | ISO 976:2013 |
| Viscosity (Brookfield RVT, spindle 3, 20 rpm, 25 °C) | 1500–4000 mPa·s | ISO 2555:2018 |
| MFFT | <0 °C | ISO 2115:2000 |
| Glass transition temperature (Tg mid-point, DSC) | −10 ± 3 °C | ISO 11357-2:2020 |
| Particle size (D50) | 0.8–1.4 µm | ISO 13320:2020 (laser diffraction) |
| Residual vinyl acetate monomer | <500 ppm | GC headspace |
| Density at 20 °C | 1.07–1.09 g/cm³ | ISO 2811-2:2011 |
How Does Ethylene Modification Shift Performance Boundaries?
The incorporation of
10–20 wt% ethylene in the copolymer chain depresses the glass transition temperature well below that of vinyl acetate homopolymer (Tg ≈
33 °C), imparting permanent flexibility to the dry adhesive film. In accelerated ageing tests per ISO
9142:2004 (method
D1,
7 days at
50 °C and
85 % RH), DA-101 films retain
≥80 % of their original elongation at break, whereas external plasticiser-containing PVAc compounds typically lose
40–60 % of elongation due to plasticiser migration and volatilisation. This differentiation becomes critical in bookbinding applications where adhesive-bridged spine folds must survive
10,000+ flex cycles (ISO
144:2017, cold-climate variant) without delamination at the hinge.
VAE copolymers also exhibit alkaline-hydrolytic stability superior to that of neat PVAc, a consequence of the random incorporation of ethylene units that disrupt the stereoregularity required for base-catalysed ester cleavage. DA-101-spiked films immersed in
pH 10.0 carbonate buffer at
40 °C for
72 hours show mass loss of
<1.5 %, compared to
6–8 % for a comparable, non-plasticised PVAc homopolymer film of equivalent initial thickness. This stability permits formulation with alkaline fillers such as calcium carbonate (up to
20 phr) without autocatalytic viscosity drift in storage.
Film Formation Kinetics and the Role of Particle Size Distribution
DA-101 coalesces primarily by capillary deformation and polymer interdiffusion, with the bimodal particle size distribution (D10 typically
0.3 µm, D90
2.8 µm) accelerating the transition from interstitial water expulsion to optically clear film formation. Rheological studies using a single-particle micronixer reveal that small-diameter particles (
<0.5 µm) pack into the interstitial voids left by larger particles (
>1.5 µm), reducing the capillary pressure required for deformation from approximately
3.0 MPa to
1.2 MPa. In industrial roll-coating applications where wet film thickness is controlled at
50–150 µm, this packing efficiency translates to a reduction in “white point” temperature—the temperature below which the dried film remains hazy—from
5 °C (for monomodal VAE) to
−2 °C for DA-101. Plant trials on a KLM 1300 roller coater (Kroenert) processing
120 g/m² of adhesive on
280 g/m² solid bleached sulphate board have demonstrated full optical clarity at
8 °C ambient and
65 % RH with an open time of
120 s, sufficient for manual lay-flat assembly without forced drying.
In flooring adhesives formulated with DA-101, moisture release through porous substrates is the rate-limiting step for initial strength development. Data obtained from a controlled-environment tensile creep tester built to EN
14293:2006 indicate that a
2 mm-thick wet adhesive layer applied to absorbent cementitious screed (
4 wt% residual moisture) develops a peel strength of
0.5 N/mm² within
45 min at
23 °C and
50 % RH. By comparison, a VAE emulsion with a monomodal coarse particle size distribution (D50>
2.0 µm) required
70 min to reach the same threshold under identical conditions, owing to slower interstitial water drainage from the film.
Where Formulators Encounter Constraints with Unmodified DA-101
DA-101 is not self-crosslinking; consequently, dry films exhibit thermoplastic behaviour with a shear storage modulus (G′) drop from approximately
200 MPa at
−20 °C to
0.5 MPa at
60 °C, as measured by dynamic mechanical analysis (DMA,
1 Hz,
3 °C/min ramp). In applications subject to sustained static loads at elevated temperatures—such as edge-glued laminated veneer lumber (LVL) beams exposed to attic temperatures above
55 °C—creep compliance under a constant shear stress of
0.1 MPa exceeds
50 µm/(m·h) after
24 h. Formulators addressing these conditions typically incorporate a post-added crosslinker; for example,
0.5–1.5 wt% (on wet adhesive) of a polyfunctional aziridine improves heat resistance as defined by EN
14257:2006 (WATT
91 test) from
<50 °C to
>100 °C, though this addition reduces pot life to
4–6 h at
23 °C and mandates agitated storage due to pH drift toward
8.0.
Water immersion resistance of DA-101 films is inherently limited by the surfactant layer that stabilises the latex. After
24 h immersion in deionised water at
23 °C per ISO
9142 method
E, unsupported films absorb
15–22 wt% water and swell in thickness by
25–35 %. Addition of
5 phr of a water-dispersible polymeric isocyanate (pMDI) reduces water uptake to
<8 wt% under the same conditions, and a D4 wood bond durability classification per EN
204:2016 becomes attainable when the isocyanate is dispersed at
800–1200 rpm using a cowles-type dissolver with a tip speed of
10–15 m/s. Incompatibility is observed when formulating with amine-based adhesion promoters such as polyethylenimine (PEI), which causes instantaneous coagulation at addition levels above
0.2 wt%, attributed to destabilisation of the anionic surfactant system.
In rigid PVC film lamination for furniture edgebanding, where the substrate contains
15–25 phr of monomeric plasticiser (typically DOP or DINP), DA-101 films can soften unacceptably within
72 h at
40 °C due to plasticiser migration into the adhesive layer. The phenomenon is measurable as a
60 % drop in Storage Modulus at
25 °C over
7 days. Such applications require either the selection of a plasticiser-resistant ethylene-vinyl chloride emulsion or the use of a barrier primer; the latter approach, using a cationically stabilised styrene-acrylic primer applied at
3–5 g/m² dry, arrests plasticiser ingress below detectable levels (
<0.5 % mass gain in the DA-101 layer) over the same time period.
Comparative Processing Windows in High-Shear Adhesive Application
In roller-bead and nozzle-spray application systems, the rheological profile of DA-101 under high shear dictates the maximum achievable line speed without misting or streaking. Capillary rheometer data (DIN
53014-1) at
10,000 s⁻¹ and
30 °C indicate a shear viscosity of
60–90 mPa·s for DA-101, compared to
110–140 mPa·s for a standardised PVAc homopolymer of similar solids content. This lower high-shear viscosity enables uniform transfer from anilox rolls engraved at
80–120 lines/cm with a cell volume of
8–12 cm³/m² at line speeds up to
200 m/min without the onset of cavitation-induced spatter. In contrast, acrylic pressure-sensitive adhesive emulsions of comparable low-frequency viscosity frequently undergo mechanical destabilisation at shear rates above
6000 s⁻¹, generating coagulum buildup on the doctor blade edge within
30 min of continuous operation. Published data for this specific configuration in a corrugator glue unit (BHS Corrugated, wet end) confirms that DA-101-based formulations achieve a clean run time of
>8 h between wash-ups, whereas acrylic alternatives require cleaning cycles every
3–4 h.
Key differentiators between DA-101 VAE, standard PVAc homopolymer, and acrylic adhesive emulsions
| Parameter | DA-101 (VAE) | PVAc homopolymer | Acrylic (typical BA/MMA) |
|---|
| MFFT | <0 °C | 15–18 °C | 0–5 °C |
| Plasticiser requirement for flexibility | None | 10–20 phr DBP required | None |
| Alkaline hydrolysis resistance | Excellent | Poor (autocatalytic) | Excellent |
| Wet tack on low-energy surfaces (HDPE, untreated) | Moderate (1.2 N/25 mm) | Low (0.4 N/25 mm) | High (3.0 N/25 mm) |
| High-shear stability at 10,000 s⁻¹ | High | Moderate | Low–moderate |
| Film clarity in thick sections (>200 µm) | Slightly hazy | Clear | Clear |
| Relative raw material cost index | 1.0 | 0.7 | 1.4 |
In high-frequency (HF) polyvinyl chloride welding of upholstery seam tapes, DA-101 films do not interfere with the diathermic heating process when the adhesive is applied as a discontinuous dot coating at
15–25 g/m². Thermographic imaging of a HF press operating at
27.12 MHz with a
2 s dwell time shows no detectable temperature gradient between the adhesive dot and the surrounding PVC film, ensuring homogeneous melt flow into the textile substrate. Homopolymer PVAc compounds containing dibutyl phthalate plasticiser have been observed to generate localised hot spots exceeding
20 °C above the surrounding film temperature under the same conditions, increasing the risk of substrate scorching and edge burn-through.
The freeze–thaw stability of DA-101, tested under ISO
1147:1995 with
5 cycles between
−15 °C and
+23 °C, results in a viscosity increase of
<50 % and no grit formation when returned to
25 °C under gentle agitation. This permits bulk storage in unheated warehouses across continental climate zones without electrical trace heating of IBC containers. The product remains pump-transferable with a
2:1 ratio air-operated double-diaphragm pump (Graco Husky
1050) after
48 h exposure at
−10 °C, a condition that would irreversibly coagulate a typical acrylic pressure-sensitive emulsion.
Mixing DA-101 with fully hydrolysed polyvinyl alcohol (PVOH, degree of hydrolysis
>98 mol%) in a ratio of
70:30 dry solids produces a structured network exhibiting a yield stress of
150–250 Pa (vane rotor,
0.5 rpm). This thixotropic body is suitable for vertical-application wood adhesives conforming to EN
205:2016 for non-structural interior joinery, where drip resistance after sag-test evaluation on vertical panels (EN
302-1:2013) must exceed
30 min without slumping. The association between PVOH and the stabilising surfactant layer of DA-101 is endothermic; consequently, the yield stress diminishes reversibly to
<30 Pa at
50 °C, permitting sprayable consistency when the adhesive is pre-warmed via an in-line tube-and-shell heat exchanger before the mixing nozzle.
A further point of difference from conventional PVAc remains the reduced tendency toward knife corrosion in acidic service. DA-101’s pH plateau at
4.0–5.5 is buffered by the acetate/acetate² equilibrium of the partially hydrolysed surface groups; immersion corrosion tests on
304 stainless steel coupons (ASTM
G48-11, method
A) performed at
40 °C for
168 h yield a mass loss of
<0.1 mg/cm², whereas unbuffered PVAc at pH
3.2 produces mass loss of
0.8 mg/cm². Maintenance logs from a multi-line converting facility that replaced a generic PVAc with a DA-101 formulation over a
12-month period documented a reduction in doctor blade replacement frequency from
2 to
0.5 blades per month on a winder-side adhesive station.
In direct food contact applications, DA-101 has been formulated into an adhesive compliant with the compositional requirements of U.S. FDA
21 CFR § 175.105 (Adhesives) and the Framework Regulation (EC)
1935/2004 for dry and fatty food types at room temperature. Migration testing under the specified
10-day total contact period at
40 °C (EU
10/2011 simulants A, D1) with a formulated adhesive containing
95 wt% DA-101 and
5 wt% approved tackifier ester showed overall migration below the
10 mg/dm² limit. No detectable primary aromatic amines (
<2 µg/kg) were found, as the emulsion contains no polyurethane prepolymer residues.
The synthesis of DA-101 occurs via a continuous loop reactor process in which ethylene is fed at a pressure of
30–50 bar into an aqueous vinyl acetate phase containing a persulfate initiator and a cellulose-based protective colloid. The reactor effluent is stripped of residual monomer through countercurrent steam distillation in a packed column, then cooled to
<35 °C before biocide addition and 250-micron bag filtration. This process route yields a batch-to-batch MFFT variation of less than
±1 °C over a
50-tonne production campaign, as monitored by a Mettler Toledo differential scanning calorimeter with a
50 µL sample sealed in an aluminium crucible under nitrogen purge.
