CW40-937 Emulsão VAE de altos sólidos para aplicações de alto desempenho

The CW40-937 high-solids vinyl acetate-ethylene (VAE) copolymer emulsion is engineered for end-uses where elevated non-volatile content, <69 0% by mass per ISO 3251:2019, must converge with low minimum film-forming temperature and cohesive strength exceeding that of conventional 55% solids dispersions. Unlike standard VAE grades that sacrifice film integrity when formulated above 60% solids due to surfactant migration and micro-cracking, CW40-937 employs a bimodal particle size distribution and a proprietary protective colloid system to maintain a continuous, flexible polymer network at ambient cure down to 2°C. The emulsion is supplied at a Brookfield viscosity of 2 500–5 500 mPa·s (ISO 2555, spindle 4, 20 rpm, 23°C) and a pH of 4.5–5.5, and it is free of alkylphenol ethoxylates (APEO) to satisfy the EC 1907/2006 (REACH) Annex XVII restriction. In production-scale trials on twin-screw compounding extruders with L/D 44 and side-feeding of inorganic fillers, the high-solids profile permitted a 12–18% reduction in drying energy demand compared with 55% solids VAE emulsions, while maintaining equivalent wet-out on corona-treated polyethylene terephthalate (PET) films at line speeds up to 180 m/min.

What Defines the Physical Profile of CW40-937?

The high-solids construct shifts the water-load burden onto the formulator without raising the glass transition temperature (T_g) of the VAE backbone, which remains near −15°C. This allows coalescent-free film formation, critical for compliance with the EU Decopaint Directive 2004/42/EC Phase II VOC limits. Films cast from undiluted emulsion and dried for 7 days at 23°C/50% RH develop a tensile strength of 3.5–4.8 MPa and elongation at break of 600–800% when tested to ASTM D638-14 Type IV specimens at 50 mm/min. The balance of cohesion and elongation is retained after 4-week water immersion at 23°C, with weight uptake typically below 12% and no visible blushing, a performance edge over polyvinyl alcohol-stabilised VAE grades that re-emulsify under prolonged moisture exposure.

Where Does CW40-937 Outperform Standard Ethylene-Vinyl Acetate Dispersions?

In high-speed pressure-sensitive adhesive (PSA) coating on siliconised release liners, the emulsion’s high-solids character directly enables lower coating weight variability on knife-over-roll systems operated at 120–160 m/min. Trials on a 1 200 mm-wide pilot coater with forced-air drying at 90°C showed that a 68% solids CW40-937 compound, thickened with 0.3 parts per hundred of an associative polyurethane thickener, deposited 22–24 g/m² dry coat weight with a coefficient of variation under 2.5%, while a 55% solids reference VAE required 32 g/m² wet to achieve equivalent dry add-on and exhibited 6% variation due to viscosity fluctuations. The resulting PSA, transfer-coated to biaxially oriented polypropylene (BOPP) film, displayed 180° peel adhesion on stainless steel of 12–14 N/25 mm (ASTM D3330/D3330M-04 Method A) and loop tack of 10–12 N/25 mm (FINAT FTM 9). Critically, the adhesive maintained shear resistance of >72 h at 1 kg/25 mm on polished steel at 23°C, a metric where many high-solids VAE grades fail prematurely because the dense particle packing limits interdiffusion and entanglement development. CW40-937’s bimodal architecture mitigates this limitation by preserving sufficient void space for chain mobility during the early coalescence phase.

Film Formation Below 0°C Without Coalescents

The MFFT of <0°C eliminates the need for high-boiling coalescing aids in exterior architectural coatings and enables application down to 2°C substrate temperature without film cracking, a requirement of EN 1062-1:2004 for exterior masonry coatings. When CW40-937 is formulated into a clear wood varnish at 45% pigment volume concentration (PVC) with a matting agent, film integrity assessed by ASTM D7306-07 (Standard Practice for Testing Low Temperature Film-Formation of Latex Paints by Visual Observation) showed continuous film at 2°C without coalescent, whereas a 55% solids VAE grade of comparable backbone composition required 2.5 wt% texanol (on total binder) to reach equivalent performance, adding 38 g/L VOC to the wet formulation. The intrinsic coalescence capability derives from the low-viscosity, mid-size particle fraction that can flow into capillary radii at the interstitial sites of the larger particles under the capillary pressure generated during the primary drying stage.

When Automotive Interior Laminates Demand Fast Set and Low Odor

Thermoforming of polyolefin foam-backed interior trims with CW40-937-based adhesives benefits from the reduced water load and the emulsion’s compatibility with blocked isocyanate crosslinkers. A water-based spray adhesive formulated with 100 parts CW40-937, 3 parts of a water-dispersible isophorone diisocyanate trimer (IPDI) prepolymer, and 0.5 parts of a polyether-modified siloxane substrate wetting agent was applied at 60 g/m² dry weight to a low-surface-energy TPO skin. After heat activation at 80°C for 45 s and lamination to a polyurethane foam core under 0.3 bar platen pressure, 180° peel strength exceeded 8 N/25 mm on a tensile tester at 300 mm/min. Odour evaluation according to VDA 270 (variant C3, 80°C) scored 2.0, and fogging per DIN 75201 Method B at 100°C/16 h yielded a photometric condensate index of <0.5 mg, meeting requirements of German OEM specifications. Published data for this specific closed-mold lamination arrangement with CW40-937 is limited outside of single-manufacturer application bulletins; however, the low residual monomer profile supports the odour findings.

Compatibility with Fillers and Rheology Modifiers

ASE-thickened systems require careful pH adjustment to avoid hydrolysis of the VAE polymer’s acetate groups; sustained pH above 9.0 leads to measurable loss of tensile strength after hot storage at 50°C for 14 days. The high-solids nature of CW40-937 also places constraints on filler pre-dispersion: when adding dry calcium carbonate directly into the emulsion under high-shear dissolver at 1 200 rpm, batch temperatures must not exceed 35°C, else skin formation in the vessel headspace and irreversible grit generation occur. In continuous static mixer lines processing 500 kg/h, inline viscosity monitoring at 300 s⁻¹ indicated optimal dispersion below 4 500 mPa·s shear viscosity without a secondary defoamer, whereas addition rates above 180 phr calcium carbonate pushed the system into dilatancy that manifested as pump cavitation.

The emulsion is manufactured under ISO 9001:2015 certified quality management and conforms to the compositional requirements of FDA 21 CFR 175.105 for indirect food-contact adhesives and German BfR Recommendation XIV for polymer dispersions when used within specified migration limits. It is listed in the ECHA Article 95 list of active substances and suppliers as compliant with the Biocidal Products Regulation (EU 528/2012) only where in-can preservatives are added by the formulator. The emulsion does not contain dibutyltin or dioctyltin catalysts, aligning with EN 71-3:2019 migration limits for toy safety. Published long-term exterior exposure data for CW40-937-specific formulations under ISO 2810 natural weathering is limited; however, accelerated QUV-B testing (ASTM G154-16, cycle 1) on 30% PVC pigmented films showed 90% retention of initial elongation after 1 000 h, provided an adequate UV absorber package is employed.