With a solids fraction of
54–56% (ISO
3251) and a Brookfield viscosity at
25 °C of
1500–3000 mPa·s (spindle 4,
20 rpm, ISO
2555), the aqueous vinyl acetate-ethylene (VAE) copolymer dispersion designated CW 40-758 occupies a mid-viscosity, high-solids niche within waterborne adhesive raw materials. The emulsion is colloidally stabilized by a polyvinyl alcohol (PVOH) protective colloid system, yielding a nonionic-to-anionic character with a pH of
4.5–5.5 (ISO
976). Its minimum film-forming temperature (MFFT), measured by differential scanning calorimetry on a Kofler bar per ISO
2115, lies at
0 ± 1 °C, reflecting an ethylene content sufficient to internally plasticize the vinyl acetate backbone without requiring external coalescing solvents. This property directly enables film formation on low-energy surfaces such as untreated biaxially oriented polypropylene (BOPP) and low-density polyethylene (LDPE) at ambient temperature. The mean particle diameter, determined by laser diffraction (ISO
13320), ranges from
0.6–1.2 μm, providing a balance between mechanical shear stability and rapid water release during drying. CW 40-758 is supplied as a ready-to-use, formaldehyde-free dispersion containing less than
1000 ppm residual vinyl acetate monomer (VAM), meeting the voluntary emission limits of the German Giscode
TMA 01 for low-emission flooring adhesives.
How Does Ethylene Content in VAE Dispersion CW 40-758 Influence Adhesion to Nonpolar Substrates?
The incorporation of ethylene segments at a mole fraction estimated between
10 and 20% along the polymer backbone reduces the glass transition temperature (Tg) to approximately
-10 °C (DMA,
1 Hz, ASTM
D7028). This low Tg imparts permanent tack and chain mobility, enabling the amorphous domains to penetrate the boundary layer of substrates with surface energies below
30 mN/m. In peel adhesion measurements according to ASTM
D1876 (T-peel,
300 mm/min crosshead speed), a
50 μm dry film of CW 40-758 laminated to untreated LDPE
30 μm film and conditioned at
23 °C and
50% RH for
24 h develops a peel force of
2.2–2.8 N/15 mm. The failure mode under these conditions is cohesive within the adhesive layer, indicating that interfacial adhesion exceeds the cohesive strength of the unfilled polymer. By contrast, vinyl acetate homopolymer emulsions with Tg above
25 °C exhibit interfacial failure on identical substrates and deliver peel values below
0.5 N/15 mm, as the rigid chains cannot dissipate energy at the interface.
The ethylene block units reduce the density of acetate dipoles, lowering the Hansen solubility parameter to a range more compatible with polyolefin surface energies. This is evident in wetting behavior: a
10 μL drop of CW 40-758 on corona-treated polyethylene (dyne level
38 mN/m) achieves a contact angle of
42° within
5 seconds (sessile drop goniometry, ASTM
D7490), compared to
68° for a high-Tg VAE analog. The practical consequence is faster coverage on high-speed laminators, reducing the risk of skip coating on engraved roller application.
In pressure-sensitive adhesive (PSA) constructions where the emulsion is compounded with
30 parts of a rosin ester tackifier dispersion (softening point
85 °C, Ring & Ball, ASTM
E28) per
100 parts dry polymer, the loop tack on stainless steel (ASTM
D6195) reaches
3.8–4.5 N/25 mm after
20 min dwell. The low MFFT of the base polymer permits film formation without heating the coater and avoids the tack loss associated with fugitive coalescents that migrate to the adhesive-substrate interface during ageing. Hot-shear creep resistance in the formulated PSA, measured as time to failure under a
1 kg static load at
60 °C (ASTM
D3654, Method A), exceeds
48 h on stainless steel when crosslinked with
0.3 wt% aluminium acetylacetonate (based on dry polymer), demonstrating that the ethylene segments do not compromise elevated-temperature cohesion if a suitable ionic crosslinking density is introduced.
Benchmarking Cohesive Strength Development in CW 40-758 Compared to Conventional Vinyl Acetate Homopolymers
The mechanical property divergence between CW 40-758 and vinyl acetate homopolymer dispersions becomes measurable in the first
72 h of film consolidation. Dynamic mechanical analysis (DMA) of films cast at
23 °C and
50% RH and aged for
7 days reveals a plateau storage modulus (G’) at
25 °C of
0.8 MPa for the VAE, versus
1.5 GPa for a homopolymer (Tg
32 °C). The homopolymer film behaves as a brittle glass at room temperature, whereas CW 40-758 remains elastomeric. This translates into shear adhesion failure temperature (SAFT, ASTM
D4498) values that track inversely with Tg: a homopolymer-based PSA reaches SAFT near
80 °C, while an uncrosslinked CW 40-758 formulation fails at approximately
50 °C. However, after ionic crosslinking, the SAFT of the VAE formulation increases to
95 °C, surpassing the homopolymer while retaining ambient tack.
The table below summarizes key performance indicators for CW 40-758 alongside two reference VAE grades—a lower-ethylene type (LE-VAE, Tg
5 °C) and a higher-ethylene type (HE-VAE, Tg
-25 °C)—as well as a standard plasticized vinyl acetate homopolymer (PVAc+DIBP, Tg
10 °C). Data were generated according to the cited standard methods on
50 μm dry films on untreated LDPE.
| Property |
CW 40-758 |
LE-VAE |
HE-VAE |
PVAc+DIBP |
Test Standard |
| Tg (DMA onset) |
-10 °C |
5 °C |
-25 °C |
10 °C |
ASTM D7028 |
| MFFT |
0 °C |
8 °C |
-8 °C |
12 °C |
ISO 2115 |
| 180° peel on LDPE |
2.5 N/15 mm |
1.2 N/15 mm |
3.1 N/15 mm |
0.4 N/15 mm |
ASTM D3330 |
| SAFT (crosslinked) |
95 °C |
110 °C |
72 °C |
85 °C |
ASTM D4498 |
| Cohesive strength (tensile) |
2.1 MPa |
4.0 MPa |
1.2 MPa |
5.5 MPa |
ISO 37 Type 2 |
The balance illustrated by CW 40-758—moderate peel, high crosslinkable cohesion, and a processing MFFT of
0 °C—positions it for applications where LE-VAE requires a coalescent and HE-VAE suffers from excessive cold flow. The homopolymer, even when externally plasticized, cannot match the dry peel on LDPE due to migration of the plasticizer into the substrate over time, which is confirmed by a
60% loss of peel after
4 weeks at
60 °C.
During storage at
40 °C for
28 days (accelerated aging per ISO
3219), the Brookfield viscosity of CW 40-758 increases by less than
15%, and the pH drift remains within
0.3 units. This stability is attributed to the PVOH protective colloid, which maintains steric barrier integrity even as a small fraction of acetate groups undergoes alkaline hydrolysis. Foam generation in recirculation lines becomes problematic when a progressive cavity pump is operated above
50 Hz without a back-pressure valve; the addition of
0.1 wt% of a polydimethylsiloxane defoamer emulsion restores coating uniformity on a rotogravure cylinder engraved with
54 lines/cm and
70 μm land depth. Wet laydown on that cylinder stabilizes at
22–28 g/m² at machine speeds up to
150 m/min. Drying tunnel air temperature is set to
120 °C, with an impingement velocity of
15 m/s to achieve residual moisture below
0.5 wt% within a dwell of
3.5 s. Failure to dry below that threshold before combining with the secondary web results in a
40% loss of initial bond strength due to entrapped water plasticizing the PVOH-rich interphase.
When Film Drying Is Interrupted by High Humidity or Low Airflow
The rate of water release from CW 40-758 films is governed by the particle packing density and the hygroscopicity of the PVOH stabilizer. In lamination environments where relative humidity exceeds
65% RH at
23 °C, the open time extends by
30–50%, and the equilibrium moisture content of the dried film increases from
1.2% to
3.5%. This residual water acts as a plasticizer, lowering the Tg temporarily and delaying the buildup of cohesive strength. Bonded assemblies removed from the nip at
80 N/cm line pressure and immediately subjected to shear exhibit
20% lower holding power than those dried at
40% RH. A practical countermeasure is an upstream infrared pre-heating section that raises the substrate surface temperature to
35–40 °C immediately before coating, reducing the effective open time by lowering the emulsion viscosity at the moment of application.
In terms of chemical incompatibility, CW 40-758 shows rapid destabilization when multivalent cations are introduced without adequate chelation. Addition of aluminium sulfate at concentrations exceeding
0.2 wt% (based on wet emulsion) induces instantaneous grit formation exceeding
200 μm and a pH drop to below
3.0, as the Al³⁺ ions displace the PVOH adsorption layer and bridge particles. Ferric chloride and calcium chloride produce similar aggregates at
0.5 wt%. Compatibility with borax is limited to
0.1 wt%; at higher levels, the borate ion crosslinks the PVOH, generating a non-spreadable gel. Amine-based pH adjusters such as 2-amino-2-methyl-1-propanol can be tolerated up to
1.0 wt% for pH adjustment to
7.5, but ammonia additions above
0.3 wt% lead to a pronounced viscosity climb due to swelling of the PVOH shell by hydroxide ions.
Specification Data and Test Methodology
The following table compiles the routine release parameters and their governing test methods, as documented in production quality records.
| Parameter |
Specification Range |
Typical Value |
Method |
| Solids content |
54.0–56.0% |
55.2% |
ISO 3251 (105 °C, 3 h) |
| Brookfield viscosity (25 °C) |
1500–3000 mPa·s |
2200 mPa·s |
ISO 2555, spindle 4, 20 rpm |
| pH |
4.5–5.5 |
5.0 |
ISO 976 |
| MFFT |
≤ 2 °C |
0 °C |
ISO 2115 |
| Mean particle size |
0.6–1.2 μm |
0.9 μm |
ISO 13320 |
| Residual VAM |
<1000 ppm |
450 ppm |
GC headspace, internal method |
| Density (20 °C) |
1.05–1.08 g/cm³ |
1.07 g/cm³ |
ISO 2811-1 |
Regulatory positioning for end-use compliance spans multiple regions. The dispersion as supplied meets the requirements of U.S. FDA
21 CFR 175.105 for indirect food contact adhesives, provided the formulated adhesive’s extractive fraction does not exceed migration thresholds defined in
21 CFR 175.300. Under EU Framework Regulation (EC)
1935/2004, the polymer may be used in food contact materials under the positive list of monomers and additives specified in Commission Regulation (EU)
10/2011 as amended, with the specific migration limit for vinyl acetate set at
12 mg/kg food simulant. The product is REACH-registered with a registration number assigned for the tonne band
1000–10 000 t/a; the Safety Data Sheet identifies no SVHC above the
0.1% w/w threshold. RoHS
2011/65/EU recast compliance is declared for the six substance groups, with lead, mercury, cadmium, hexavalent chromium, PBBs, and PBDEs each below
100 ppm by weight in the dry polymer. Volatile organic compound (VOC) content, determined by EPA Method
24, is below
0.5 wt%, enabling formulation of carpet adhesives meeting the Carpet and Rug Institute’s Green Label Plus maximum emission limits for TVOC of
≤ 0.5 mg/m³ at
24 h.
In the context of hygiene article assembly, CW 40-758 transfers to nonwoven substrates with minimal strike-through when applied via a multi-bead slot-die coating head at
2–5 g/m² dry add-on. The polymer complies with the Standard
100 by OEKO-TEX® for product class I (articles for babies), having been tested for extractable heavy metals, formaldehyde, and alkylphenol ethoxylates. Phtalates (DINP, DEHP, DNOP, DIDP, BBP, DBP) are not detected above the
0.01% reporting limit by GC-MS extraction. These attributes position the grade for compliance with EU Ecolabel criteria for absorbent hygiene products (Commission Decision
2014/763/EU), provided formulated article components do not introduce prohibited preservatives.
