The product CW40-906 is a vinyl acetate-ethylene copolymer emulsion engineered without alkylphenol ethoxylate surfactants, classified under the designation APEO-free VAE. Typical supplied properties include a non-volatile content of
55 ± 1% (ISO 3251, 2 g, 120 °C, 2 h), a Brookfield RVT viscosity of
2500 mPa·s at 20 rpm with spindle 4 (ISO 2555), a pH of
4.8 (ISO 976), and a minimum film-formation temperature below
0 °C (ISO 2115). The primary application domain encompasses waterborne laminating adhesives for flexible packaging, pressure-sensitive adhesive formulations, high-solids architectural caulks, and construction compounds requiring low-emission binder systems. Where conventional VAE grades rely on APEO-based emulsifiers to stabilize the latex and plasticize the polymer, CW40-906 achieves equivalent or improved film coalescence through a modified ethylene-incorporation ratio and a proprietary non-ionic protective colloid, eliminating the regulatory and toxicological burdens associated with nonylphenol and its ethoxylates. This compositional shift enables formulators to satisfy EU Directive
2003/53/EC restrictions, the US EPA Safer Choice criteria, and the Nordic Swan Ecolabel without additional reformulation steps.
What Distinguishes CW40-906 from Conventional APEO-Containing VAE Binders?
Comparative peel adhesion data on corona-treated biaxially oriented polypropylene (BOPP) film, obtained per
ASTM D903 at
23 °C and
50% relative humidity, show a
180° peel strength of
2.5 N/15 mm for CW40-906 versus
2.1 N/15 mm for a standard APEO-stabilized VAE of equivalent solids. The difference is traceable to the migration behaviour of surfactant species during film formation: APEO molecules tend to bloom to the adhesive-substrate interface, creating a weak boundary layer, whereas the surfactant system in CW40-906 remains more uniformly distributed within the polymer matrix as verified by time-of-flight secondary ion mass spectrometry depth profiling. Volatile organic compound content, determined by headspace gas chromatography per
ISO 11890-2, remains below
500 ppm for CW40-906, whereas the APEO-containing comparator registers approximately
1500 ppm due to residual free alkylphenols and low-molecular-weight glycol ethers. Mechanical stability under high-shear conditions is also altered: CW40-906 withstands
30 min of mixing in a Silverson L5M rotor-stator at
5000 rpm without grit formation exceeding
100 µm, while the APEO grade develops
>200 µm coagulum after
15 min under identical conditions.
Table 1 — Selected performance properties compared: CW40-906 vs. conventional APEO-containing VAE (solids 55%)
| Property | Test method | CW40-906 | Conventional APEO-VAE |
|---|
| Glass transition temperature (Tg, midpoint) | ISO 11357-2 | 0 °C | -5 °C |
| Minimum film-forming temperature | ISO 2115 | <0 °C | <0 °C |
| 180° peel on BOPP | ASTM D903 | 2.5 N/15 mm | 2.1 N/15 mm |
| Dry bond strength on beech wood (tensile shear) | ISO 6238 | 9.2 MPa | 8.4 MPa |
| VOC content | ISO 11890-2 | <500 ppm | ~1500 ppm |
| Mechanical stability (Silverson L5M, 5000 rpm, 30 min) | Internal method | Grit 100 µm | Grit 200 µm at 15 min |
| Odour (subjective panel, 0–5 scale) | Internal | 0.5 | 2.0 |
When the Emulsion Replaces Solvent-Based Adhesives in Flexible Packaging
Laminating converters substituting a solvent-borne polyurethane adhesive with a CW40-906-based waterborne system on a Nordmeccanica Simplex laminator record a reduction in total volatile organic compound emissions from
12 g/m² (ethyl acetate basis) to less than
0.5 g/m², bringing the process into immediate compliance with the Solvent Emissions Directive (
1999/13/EC) without reliance on regenerative thermal oxidisers. The emulsion is applied via a reverse gravure station: cylinder line screen
100 lines/cm, coating weight controlled at
4.5 g/m² dry, drying tunnel temperature profile
40–60 °C over three zones with an air velocity of
25 m/s. Web tension is maintained at
100 N for
12 µm metallized PET and
50 µm LDPE sealant webs, achieving a laminate bond strength of
>2.0 N/15 mm after
24 h ambient cure, as measured by the
ASTM F904 peel test. A critical processing bottleneck appears when gravure pan residence time exceeds
15 min: foam generation under high-shear doctor blade contact elevates the emulsion surface area, causing viscosity drift from
2500 mPa·s to
4200 mPa·s and resulting in coating weight deviations beyond ±
0.3 g/m². Incorporation of a non-silicone, BIT-free defoamer at
0.3% on total formulation and installation of a pan deaeration loop with
50 µm in-line filter mitigates this. Crosslinking with polyaziridine (
2% on binder solids) improves chemical resistance to ethyl acetate and water immersion (
ASTM F904 maintained>1.5 N/15 mm after
1 h immersion at
60 °C), but limits pot life to
4 h as viscosity rises above
1000 mPa·s (Brookfield,
20 rpm), requiring daily equipment cleaning cycles.
Incorporation into high-solids architectural caulks and sealants leverages the emulsion’s plasticizer-free flexibility and APEO-free profile to qualify under
LEED v4.1 low-emitting materials credit requirements. A typical formulation loads
40% calcium carbonate filler (particle size
50 µm) into CW40-906, thickened with a hydrophobically modified alkali-swellable emulsion (HASE) to a final viscosity of
3000–5000 mPa·s (Brookfield,
10 rpm). Cured films exhibit tensile elongation exceeding
600% (
ASTM D412, die C) and a secant modulus at
100% extension of
0.8 MPa. Unlike APEO-containing VAE sealants, no extractable alkylphenols leach into water as demonstrated by migration testing per
EN 1186-3 (simulant A,
10 days at
40 °C), confirming suitability for indirect food-contact applications under
FDA 21 CFR 175.105. The absence of fugitive plasticisers eliminates plasticiser migration-induced delamination on painted substrates, a failure mode observed with competitive polymer dispersions when adhered to alkyd-painted wood after
6-month outdoor exposure in northern European climate.
Film Clarity and Block Resistance — Observations from Production-Scale Trials
When CW40-906 is applied as a waterborne overprint varnish on a Bobst F&K flexographic press using an anilox volume of
8.0 BCM and a
75° doctor blade angle, dry film haze measured per
ASTM D1003 on
125 µm PET substrate is
5.2%, compared to
8.8% for a standard VAE varnish and
12.1% for an acrylic emulsion of comparable T
g. Block resistance under
2 psi pressure at
50 °C for
24 h (face-to-face contact) shows no fibre tear or ink transfer on paperboard, a result attributed to the emulsion’s
0 °C T
g coupled with rapid surface hardness development: Koenig pendulum hardness (
ISO 1522) reaches
45 s after
24 h and
85 s after
7 days at
23 °C/50% RH. Machine-speed observations up to
200 m/min reveal no streaking or foaming, provided the emulsion is pre-filtered through a
150 µm mesh and the pH is adjusted to
7.0–7.5 with
28% aqueous ammonia to optimise rheology for anilox metering. A limitation emerges under prolonged UV exposure: after
1000 h of QUV-A weathering (
ASTM G154, cycle 1), ΔE colour difference exceeds
3.0 due to photolytic degradation of the ethylene-rich backbone; incorporation of a benzotriazole UV absorber and hindered amine light stabiliser at combined
2% on binder solids is necessary to limit yellowing for exterior graphic arts applications.
Storage Stability and Bacterial Resistance in Bulk Holding Tanks
CW40-906 is preserved with a blend of chloromethylisothiazolinone and methylisothiazolinone providing an active concentration of
1.5 ppm in the as-packed emulsion, demonstrating a Grade
0 rating in the
ISO 11930 challenge test against Pseudomonas aeruginosa and Aspergillus brasiliensis. Storage in high-density polyethylene totes at
5–30 °C maintains viscosity drift below
10% over
3 months (sampled through a
150 µm in-line screen). The latex is not freeze-thaw stable: exposure to temperatures below
-2 °C for more than
4 h results in irreversible coagulum formation that cannot be redispersed by mixing. Bulk transfer should employ low-shear progressive cavity pumps with a rotational speed not exceeding
150 rpm; centrifugal pumps or high-shear gear pumps produce microcoagulum that elevates
80 µm screen residue above
0.5 g/L. Plant-scale experience indicates that a weekly recirculation for
30 min at
20 rpm is sufficient to prevent surface skinning, provided the vault headspace is blanketed with nitrogen at
0.2 bar overpressure.
Table 2 — Typical physical properties of CW40-906 (coagulum-free sample, 25 °C)
| Property | Specification limits | Test method |
|---|
| Non-volatile content | 54–56% | ISO 3251 (2 g, 120 °C, 2 h) |
| pH | 4.5–5.5 | ISO 976 |
| Viscosity (Brookfield RVT, spindle 4, 20 rpm) | 2000–4000 mPa·s | ISO 2555 |
| Density | 1.07 g/cm³ | ISO 2811-1 |
| Minimum film-forming temperature | <0 °C | ISO 2115 |
| Particle size (median, laser diffraction) | 0.8–1.6 µm | ISO 13320-1 |
| Residual vinyl acetate monomer | <1000 ppm | ISO 13741-1 |
| Screen residue (80 µm) | <0.5 g/L | Internal method |
