CW40-906 Emulsão de VAE de viscosidade média livre de APEO para adesivos

CW40-906 is a surfactant-stabilized, APEO-free vinyl acetate-ethylene (VAE) copolymer emulsion supplied at a nominal solids content of 54.5–55.5 % and a Brookfield viscosity (LVF, spindle 3, 20 rpm, 25 °C) in the range 2800–3800 mPa·s. The product is manufactured with a non-ionic stabilizer system that excludes alkylphenol ethoxylates entirely, aligning with regulatory frameworks that restrict APEO usage in adhesive articles destined for EU and North American markets. Typical pH is adjusted to 4.5–5.5 (ISO 976). The dispersion particle size distribution, measured by laser diffraction, exhibits a median diameter (D₅₀) of 0.8–1.2 µm, a moderately coarse configuration that contributes to shear-thinning flow behavior and controlled penetration on porous substrates such as uncoated paperboard and cotton textiles. CW40-906 is intended for waterborne adhesive compounding where medium viscosity serves as a compromise between low-viscosity grades that tend to over-penetrate and high-viscosity grades that necessitate high application pressures.

Process Viscosity and Adhesive Application Window

The mid-range viscosity profile of this emulsion directly influences machine settings on roll-coating and bead-application lines. When applied via a three-roll nip coater with a chrome-plated metering roll and a Shore A 60–70 rubber transfer roll, the fluid exhibits a pseudoplastic index (calculated as η_2/20) of 0.32–0.38. This property permits film thicknesses of 40–60 µm wet at line speeds between 15–40 m/min without dripping, provided the gap is maintained within ±10 µm. In slot-die coating systems, inlet pressure remains below 0.5 MPa at a die width of 300 mm and a pump delivery rate of 1.2–1.8 L/min, eliminating the need for feed pumps rated above 5 bar. For sprayable contact adhesives formulated at 25–35 % emulsion content and air-atomized with a 0.8–1.2 mm nozzle, dynamic surface tension measured by maximum bubble pressure (50 ms surface age) registers 38–42 mN/m, which is sufficient to wet corona-treated low-density polyethylene without cratering. The rheological response during storage at 5 °C must be noted: after 7 days, a slight viscosity rise of 200–400 mPa·s is reversible upon gentle agitation at 100 rpm for 15 minutes.

How does CW40-906 differ from conventional APEO-containing VAE grades?

Traditional APEO-stabilized VAE emulsions rely on nonylphenol ethoxylate surfactants that contribute to wetting and dynamic stabilization at low addition levels but introduce environmental persistence concerns addressed under REACH Annex XVII (entry 46) and U.S. EPA Significant New Use Rules. In CW40-906, APEO substitution is achieved with a combination of secondary alcohol ethoxylate and polymeric steric stabilizers. The trade-off manifests in substrate wetting on low-energy surfaces: uncorrected contact angle on untreated polypropylene (DIN 55660-2) is 72–76° compared to 64–68° for an equivalent APEO-containing control. Therefore, formulators targeting polyethylene or polyolefin films routinely add 0.1–0.3 % of a silicone-based superwetter to restore dynamic spreading. On porous surfaces, however, the difference becomes negligible; on birch veneer with a surface roughness (Ra) of 6–8 µm, the emulsion with 5 wt% dibutyl phthalate plasticizer exhibits identical penetration depth (80–120 µm in cross-section microscopy) to the APEO-based comparator after 30 s dwell time. Adhesion performance on aluminum (alloy 3003, chromic acid anodized) follows lap shear values per ASTM D1002: after 7-day conditioning at 23 °C, 50 % RH, crosslinking with 2 wt% (based on emulsion solids) of a blocked isocyanate dispersion yields 5.8–6.4 MPa, within 5% of the APEO reference. Heat resistance, tested as static shear at 80 °C under 500 g load, records a failure time exceeding 120 minutes for both systems, provided the film is fully coalesced at 45 °C for 24 h after application. The primary operational boundary for CW40-906 arises in highly alkaline formulations (pH> 8.5), where the non-ionic stabilizer package is less tolerant of saponification side reactions than conventional APEO systems; viscosity drift can exceed 15% within 48 hours at 40 °C. Through-formulation compatibility extends to polyvinyl alcohol protective colloids. When blended with partially hydrolyzed PVOH (degree of hydrolysis 87–89 %, 4 % solution viscosity 22–26 mPa·s) at a dry ratio of 15:85 PVOH:VAE, the mixture exhibits no phase separation after 3 months at ambient storage. This combination is particularly relevant for repulpable paper-adhesive applications that require water dispersibility after use. In the area of pressure-sensitive adhesive compounds, tackifier dispersion addition to CW40-906 follows predictable softening. Starting with a base emulsion possessing a MFFT of 4 °C (ISO 2115), incremental additions of a rosin ester dispersion (softening point 85 °C, particle size 0.5 µm) at 10, 20, and 30 parts per hundred of wet emulsion yield the performance data shown below, using 25 µm dry films on 36 µm PET backing. Testing is conducted at 23 ± 1 °C, 50 ± 5 % RH.

Effect of tackifier loading on PSA performance — CW40-906

Tackifier addition (phr wet)	Loop tack (N/25 mm) ASTM D6195	180° peel adhesion (N/25 mm) ASTM D3330 (30 min dwell)	Static shear (min) ASTM D3654 (1 in² × 1 kg)
10	3.2	2.9	>4000
20	5.8	4.7	2100
30	8.1	6.5	380

The shift from cohesive to adhesive failure mode at 30 phr tackifier indicates that the medium-viscosity VAE matrix accommodates a high load of low-molecular-weight tackifier before losing cohesive strength, an attribute that supports broad formulation latitude for removable and permanent paper labels.

Understanding the Role of Ethylene Content in VAE Copolymers

The internal plasticization contributed by the ethylene comonomer — approximately 14–16 wt% in the polymer backbone for CW40-906 — eliminates the need for external coalescing solvents above 2 wt% under normal ambient conditions. The glass transition temperature (Tg, DSC midpoint, ISO 11357-2) resides at −12 ± 2 °C, conferring a flexible film with elongation at break exceeding 600 % (ISO 527-3, film thickness 150 µm, conditioned 14 days at 23 °C, 50 % RH). This intrinsic flexibility is leveraged in textile lamination adhesives, where cyclic stretch recovery of 88 % after 50 cycles at 20 % strain (Instron grip separation 50 mm, crosshead speed 200 mm/min) is recorded without delamination from cotton poplin fabric. By comparison, a high-viscosity VAE grade (viscosity 8000–12000 mPa·s) with identical ethylene content requires higher application pressure and shows slower stress relaxation, often creating visible strike-through on lightweight non-woven webs. Conversely, low-viscosity emulsion (below 800 mPa·s) with the same chemistry exhibits excessive migration under heat-seal bars at temperatures above 120 °C. The moderate viscosity of CW40-906 establishes a balanced rheology for both spray and roll-coat lamination without additive thickening, saving a formulation step that would otherwise introduce polyurethane associative thickeners and their associated sensitivity to ionic strength. Wood assembly adhesives formulated with CW40-906 and combined with 10–15 wt% calcium carbonate filler (mean particle size 3 µm) maintain a viscosity of 6000–9000 mPa·s at 1 s⁻¹ shear rate, suitable for bead extrusion from a 4 mm nozzle. On beechwood adherends conditioned to 12 % moisture content, wet tack (measured as probe tack with a 5 mm stainless steel cylinder, 50 N contact force, 0.5 s dwell) reaches 1.2–1.5 N, allowing immediate holding without press time beyond 60 s. Pressing at 0.5 MPa for 20 min followed by 7-day room-temperature cure produces dry shear strength of 10.5–12.0 MPa (EN 205) with wood failure percentage routinely above 70 %. When these assemblies are subjected to 4-hour water soak at 20 °C, residual shear strength falls to 3.8–4.5 MPa, classifying the bond as D3 per EN 204 without crosslinker addition. For D4 durability, incorporation of 5 wt% polymeric MDI (NCO 28 %) raises water-soak strength to 7.2–8.0 MPa, a performance window equivalent to many APEO-containing D4-grade VAE adhesives. If open time on porous substrates dictates formulation adjustment, the medium-viscosity nature of the emulsion permits extension by incorporating 2–5 wt% glycerin or propylene glycol without phase inversion. On birch plywood at 20 °C, 65 % RH, open time is extended from 6 minutes to 14 minutes with 3 wt% glycerin, as determined by the point at which wet transfer to a second substrate drops below 50 % of initial value. However, residual plasticizer in the dried film elevates creep compliance by 25–30 %, a factor that must be weighed against assembly line layout. The compatibility with protective colloids such as polyvinyl alcohol influences the water-redispersibility of dried films. In paper converting where repulpability is mandated by recycling standards (e.g., PTS-RH 021/97), films cast from CW40-906 alone disintegrate within 12 minutes in 40 °C water under 300 rpm stirring. Blending with 15 phr of fully hydrolyzed PVOH (degree of hydrolysis 98–99 %) extends disintegration time to 22 minutes, still within the 30-minute maximum specified by many mill protocols.

Comparative emulsion specifications (typical values)

Property	CW40-906	Low-viscosity APEO-free VAE	Conventional APEO VAE
Brookfield viscosity, mPa·s (ISO 2555)	3300	400	2500
Solids content, % (ISO 3251)	55.0	55.0	55.0
pH (ISO 976)	4.8	4.7	5.5
Surface tension, mN/m (DIN 53914, Du Noüy)	40	38	35
Alkylphenol ethoxylate (APEO) content	Below detection limit (10 ppm)	Below detection limit	4200 ppm NPEO
Film Tg, °C (DSC)	−12	−10	−11
MFFT, °C (ISO 2115)	4	3	5

The emulsion must be protected from repeated freeze-thaw cycling. After three cycles between −10 °C and 23 °C, viscosity increased by 30–45 % and localized grit formation (150 µm filter residue exceeding 0.1 %) was observed. Containers should be stored at 5–35 °C and the material used within 6 months of the production date stamped on the certificate of analysis. Mixing equipment with high-shear dispersers exceeding 2000 rpm or dissolver blades imparting tip speeds above 8 m/s can introduce microfoam that persists due to the non-ionic surfactant system; sustained vacuum deaeration at −0.9 bar for 20 minutes post-blending resolves this. When formulating adhesives that contact food indirectly through packaging, statements of compliance under FDA 21 CFR 175.105 (“Adhesives”) and the BfR Recommendation XIV apply, provided that the end formulation is not subject to migration limits that exceed 10 mg/dm² total extractives. No intentionally added primary aromatic amines or phthalates are used in the manufacturing of CW40-906. Full toxicological and eco-toxicological summaries are contained in the product safety data sheet, which should be reviewed before any new commercial application. The absence of APEO surfactant does not alter the copolymer’s resistance to UV-induced discoloration in indoor applications. Accelerated QUV weathering (ISO 4892-3, cycle 1, 500 hours) of unpigmented films shows ΔYI (yellowness index) below 2.5, comparable to APEO-containing controls. Exterior durability, however, requires additional UV absorber and hindered amine light stabilizer packages, as the neat VAE film embrittles beyond 1000 hours of QUV exposure owing to photo-oxidative chain scission typical of ethylene sequences. For high-speed case and carton sealing where compression cycle speeds exceed 50 cycles/min, the emulsion can be formulated with 0.05–0.2 wt% of a high-molecular-weight poly(ethylene oxide) thickener to adjust high-shear viscosity to 1500–2500 mPa·s at 1000 s⁻¹, a shear rate representative of the nip region. This modification does not adversely affect adhesion to clay-coated SBS board, with fiber tear values remaining above 95 % at 0.1 s open time in instrumented bond-testing fixtures. Data collected on a production rotary die-cutter with integrated gluing at 80 m/min line speed confirmed bond consistency within ±8 % lap shear coefficient of variation over 10,000 cartons, provided adhesive temperature is maintained at 25 ± 2 °C via jacketed feed hoppers. Without temperature control, seasonal fluctuations from 15 °C to 35 °C resulted in viscosity swings that reduced open time consistency by a factor of two, underscoring that medium-viscosity VAE adhesives demand thermal management in high-throughput packaging lines to maintain uniform application weight. In direct comparison with polyurethane dispersion (PUD)-based adhesives for flexible packaging, CW40-906 does not achieve the same level of chemical resistance to ethyl acetate or olive oil, but its cost per dry kilogram is substantially lower, and the elimination of isocyanate monomer handling simplifies workplace safety compliance. For dry food packaging lamination to OPP or metallized polyester films, bond strengths of 1.5–2.0 N/15 mm (ASTM F904) are achievable after 48-hour cure when laminated with a 6 g/m² dry coat weight and nip temperature of 70 °C. This positions the product as a viable alternative for structures that do not require aggressive chemical resistance or boil-in-bag performance.