CW40-960 Emulsão de VAE livre de APEO de altos sólidos para têxteis e impermeabilização

CW40-960 is a high-solids vinyl acetate-ethylene (VAE) copolymer dispersion formulated entirely without alkylphenol ethoxylate (APEO) surfactants. The emulsion exhibits a solids content of 58.0 ± 1.0 % by mass (ISO 3251), a pH of 4.5–5.5 (ISO 976), and a Brookfield RVT viscosity of 2 500–5 500 mPa·s (spindle 4, 20 rpm, 23 °C). Its minimum film-forming temperature (MFFT) is 0 °C (ISO 2115), and the dried polymer exhibits a glass transition temperature (Tg, midpoint, DSC) of approximately 5 °C. The product is preserved with a formaldehyde-free biocide system and carries a residual monomer content below 500 ppm for both vinyl acetate and ethylene, aligning with the voluntary emission limits of the German Committee for Health-Related Evaluation of Building Products (AgBB) scheme. The APEO-free design pre-empts the REACH Annex XVII entry 46 restriction on nonylphenol and nonylphenol ethoxylates and meets the ZDHC Manufacturing Restricted Substances List (MRSL) version 3.1, enabling use in OEKO-TEX Standard 100 certified textile articles up to product class I.

Aqueous Phase Stability and Coating Rheology Under High-Shear Conditions

The high-solids architecture of CW40-960 shifts the critical pigment volume concentration (CPVC) relative to conventional 50 % solids VAE grades, permitting reduced thickener demand when formulating for knife-over-roll and rotary-screen textile coating. However, the non-APEO surfactant package elevates the emulsion’s dynamic surface tension to 42–46 mN/m at 1 Hz bubble frequency (maximum bubble pressure method), compared with 36–38 mN/m for typical nonylphenol ethoxylate-stabilised grades. This shift increases the foaming tendency during recirculation in an open coating pan; dense, stable microfoam can entrain if the line speed exceeds 20 m/min and the weir height is insufficient to maintain laminar flow. Trials on a 3-roll inclined kiss coater (roll diameter 300 mm, rubber hardness 65 Shore A) processing a 55 % solids compound with 1.2 % polyacrylate thickener showed that foaming was suppressed only when a mineral oil-based defoamer (active content 20 %) was metered into the return line at 0.15 % on wet weight. Under these conditions, high-shear viscosity measured with a cone-and-plate rheometer at 10 000 s⁻¹ (ISO 3219) remained at 110–140 mPa·s, a range that prevents misting and ensures smooth shear-thinning behaviour, whereas a foam-affected batch exhibited viscosity fluctuations of ±30 % and visible pinholing in the dried film. In textile backcoating for automotive carpet tile, the emulsion is applied undiluted via an engraved roller (line count 40 lines/cm, cell volume 28 cm³/m²) onto a needlepunched polyester nonwoven at a line speed of 15–25 m/min. Drying is accomplished in a four-zone impingement oven with setpoint temperatures of 120/140/150/140 °C and a total residence time of 90 s. The high solids content reduces the water load by approximately 18–22 % compared to a 50 % solids reference, yielding a dry add-on of 35–50 g/m² with a moisture content ≤0.5 % at the wind-up. The resulting backcoating delivers a tuft lock strength exceeding 45 N (ISO 4919) without additional crosslinker, attributed to the emulsion’s ethylene-modified backbone that maintains flexibility at the interface between primary and secondary backings.

What Drives the Shift to APEO-Free Emulsions in Certified Textile Production?

The elimination of APEO surfactants is no longer optional for textiles entering the European Union, as the restriction of nonylphenol ethoxylates under REACH Annex XVII (entry 46) imposes a maximum concentration of 100 mg/kg (0.01 % by mass) on textile articles that can be washed in water. Beyond regulatory compliance, APEO surfactants are known to degrade into endocrine-disrupting nonylphenol species in wastewater treatment plants, and their removal from the manufacturing chain is a pillar of the ZDHC Roadmap to Zero programme. CW40-960 eliminates this burden without resorting to high-EO fatty alcohol ethoxylates that can increase film sensitivity to water. Migration testing according to EN 14638 confirms that the dry polymer film releases APEO below the method detection limit of 1.0 mg/kg. This makes the emulsion suitable for direct-skin-contact textile applications (OEKO-TEX class I) and reduces detection risk during random surveillance sampling of finished goods.

Film Mechanics and Barrier Function in Cementitious Waterproofing

When CW40-960 is incorporated into a two-component cementitious waterproofing slurry, the high-solids VAE contributes to crack-bridging capability and water impermeability without requiring excessive water addition. A typical formulation blends the emulsion with ordinary Portland cement CEM I 42.5 R, graded silica sand (0.1–0.3 mm), and a polycarboxylate superplasticizer at a polymer-to-cement ratio (p/c) of 0.10–0.15 by solid mass. The slurry exhibits a pot life of 45–60 minutes at 23 °C, which is 10–15 minutes longer than that of a comparable styrene-butadiene (SB) latex-modified mix, because the VAE does not chelate calcium ions to the same extent. Application by notched trowel at a wet thickness of 2 mm onto a primed concrete substrate yields a cured membrane that meets the requirements of EN 14891 for liquid-applied waterproofing products: watertightness under 1.5 bar hydrostatic pressure for 24 h without penetration, and crack-bridging at 0.75 mm crack width after 7 days of standard curing (23 °C, 50 % RH) followed by 21 days of immersion in 10 % NaOH solution. The latter alkali resistance stems from the saturated carbon backbone and the ethylene segments that resist saponification under high-pH conditions. The pure polymer film, cast and dried for 3 minutes at 130 °C, develops a tensile strength of 5.5–7.5 MPa and an elongation at break of 600–800 % (ISO 527-3, specimen type 5, test speed 200 mm/min). After immersion in deionised water for 24 h at 23 °C, water absorption reaches 12–16 % and the wet tensile strength retention is 78–84 %, a value that is 15–20 percentage points higher than that of an APEO-containing VAE film of equivalent solids tested under identical conditions. The difference is attributed to the absence of migrating surfactants that plasticise the polymer-water interface and weaken inter-particle cohesion. Table 1 summarises the mechanical and barrier characteristics against two internal references.

Table 1 – Comparative film properties of CW40-960 and an APEO-containing 58 % solids VAE emulsion

Property	CW40-960	APEO-containing VAE	Test method
Solids content	58.1 %	57.9 %	ISO 3251
Tensile strength (dry)	6.7 MPa	6.5 MPa	ISO 527-3
Elongation at break (dry)	720 %	690 %	ISO 527-3
Water absorption (24 h)	13.5 %	16.8 %	ISO 62 (modified for free film)
Wet tensile strength retention	81 %	64 %	ASTM D751 (procedure A, grab method)
APEO content (EN 14638 extract)	<1 mg/kg	2 450 mg/kg	EN 14638, LC-MS/MS
VOC content (EPA Method 24)	<0.5 g/L	<0.5 g/L	EPA Method 24

The high-solids nature, while beneficial for drying economy and film build, introduces a rheology-related processing boundary that must be respected when coating onto dense substrates such as glass-reinforced polyester mat for waterproofing membranes. At wet film thicknesses exceeding 200 µm, the surface of the coating can skin over before the bulk has reached the phase-inversion point, especially if the ambient relative humidity exceeds 75 % at 25 °C. In a production trial on a reverse-roll coater, a wet film deposit of 230 µm on a polyethylene terephthalate (PET) carrier dried in a convective oven (air temperature 130 °C, air speed 2 m/s) developed microblisters across the full web width once the exhaust humidity exceeded 80 %. Reducing the wet film to 170 µm eliminated the defect without changing the temperature profile, but the dry film thickness dropped from 110 µm to 82 µm, necessitating a second pass to meet the EN 13956 puncture resistance requirement of 750 N on the finished membrane. This illustrates the operational window: under humid conditions, the safe wet-film thickness limit for single-pass drying is approximately 180 µm unless infrared pre-gelling is installed upstream of the convection oven.

When Ambient Humidity Exceeds 75 % RH During Film Drying

The blistering phenomenon is a direct consequence of the rapid surface film formation rate of high-solids VAE. At 75 % RH, the equilibrium moisture content of the polymer film is 4–5 %, and the water evaporation rate from a 200 µm wet film is approximately 0.8 kg/m²·h under forced convection. The skin forms within 30–40 s at 130 °C, trapping moisture that later expands and ruptures the film. To circumvent this, coating lines handling waterproofing membranes often employ an infrared pre-dryer zone with a peak wavelength of 2.5–3.5 µm and a power density of 40–60 kW/m². This energy input raises the web surface temperature to 70–80 °C within 10 s, driving out a significant portion of the water through the still-open polymer matrix before the coalesced skin closes. With such a pre-dryer, wet films up to 280 µm have been dried blister-free at 85 % RH on a production line operating at 8 m/min, though the maximum temperature in the subsequent convection zones was lowered to 120 °C to avoid post-cure tackiness. This configuration is documented in technical bulletins from leading coated fabric manufacturers processing VAE-based waterproofing laminates. The compatibility profile of CW40-960 with typical formulation additives must be strictly observed to maintain shelf stability and coating performance. Hydroxyethyl cellulose (HEC) and alkali-swellable emulsion (ASE) thickeners can be incorporated directly into the emulsion under moderate agitation (500–800 rpm, Cowles blade) without destabilisation, provided the aqueous thickener solution is pre-diluted to 3–5 % solids before addition. Polyurethane-based associative thickeners (HEUR), on the other hand, have been observed to phase-separate when dosed into the undiluted emulsion at 0.5 % active on total formulation, likely due to competitive interaction with the stabilizing surfactant layer; pre-diluting the emulsion with demineralised water to a solids content of 40 % prior to HEUR addition resolves this incompatibility. Coalescing agents of the ester-alcohol type (e.g., 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate) are effective at 2–4 % on binder solids to depress the MFFT to −5 °C for low-temperature textile finishing, but each 1 % of coalescent increases the water absorption of the cured film by approximately 1.5 %, and wet tensile strength retention drops accordingly. There is therefore a direct trade-off between low-temperature application window and waterproofing integrity.

Non-APEO VAE Versus Solvent-Borne Polyurethane: Emission Profiles and Softness

In textile interlinings and apparel coatings, solvent-borne polyurethane (PU) solutions still command a share of the market for their soft hand and fast drying, but their volatile organic compound (VOC) emission burden is an order of magnitude higher. CW40-960 contains VOC below 0.5 g/L, measured by EPA Method 24, whereas a typical one-component PU solution at 30 % solids in methyl ethyl ketone/toluene releases over 600 g/L of VOC during drying. Beyond the environmental aspect, the high-solids VAE emulsion can be formulated with a soft hand modifier—such as a high-molecular-weight polydimethylsiloxane emulsion—to achieve a drape stiffness (ISO 9073-7) of 2.5–3.0 cN·cm on a 65 g/m² polyester woven base, which is comparable to the handle of a solvent-cast PU coating. The absence of residual isocyanates and blocked isocyanate crosslinkers further eliminates the risk of sensitizing workers to diisocyanates, a concern that has driven the EU’s restriction on diisocyanates under REACH (training requirement since August 2023). Storage stability of CW40-960 is maintained for 12 months when kept in sealed containers at 5–30 °C, protected from frost. Freeze-thaw cycles cause irreversible agglomeration; the recovered material after one freeze event exhibits a grit content (filter residue on 40 µm mesh) exceeding 500 mg/kg, whereas fresh emulsion registers below 50 mg/kg. Therefore, tank farms and feed lines in textile coating plants must be heat-traced if ambient winter temperatures fall below 2 °C. During prolonged line stoppages, the coating pan must be covered and the emulsion gently recirculated at low shear to prevent skinning, as the high-solids surface can form a partially coalesced skin within 15–20 minutes at 25 °C and 40 % RH. Off-line salvage of lightly skinned material is possible by filtering through an in-line bag filter of 100 µm rating, but operator intervention to dispose of hardened chunks before restart is essential to avoid coating defects and doctor blade wear.

Table 2 – Processing boundary summary for CW40-960 in waterproofing membrane coating

Parameter	Safe operating range	Critical limit	Observation when exceeded
Wet film thickness (single pass)	100–180 µm	≥200 µm at ≥75 % RH	Microblistering, loss of interlayer adhesion
Coater pan temperature	18–28 °C	≥32 °C	Irreversible skinning within 10 min, viscosity drift
Drying air temperature (zone 1)	120–140 °C	≥155 °C	Surface tack, potential yellowing
Line speed (reverse-roll coater)	6–12 m/min	<5 m/min	Excessive heat exposure, film embrittlement
p/c ratio in cementitious formulation	0.10–0.15	≥0.20	Pot life <20 min, retarded cement hydration
Storage temperature	5–30 °C	≤0 °C	Freeze coagulation, permanent grit

The emulsion is fully miscible with standard pigment dispersions and fillers used in textile printing pastes, but formulations containing zinc oxide or magnesium oxide at levels above 2 % on binder solids cause a measurable pH rise above 6.0 over 72 hours, leading to viscosity build and eventual destabilisation. Acid-buffered dispersions with a pH of 8.0–9.0 maintain long-term compatibility. For waterproofing applications demanding an elongation at low temperature below −10 °C, an external plasticizer such as dibutyl phthalate-free benzoate ester is effective at 5–8 %, but the environmental profile of the final article must then be validated for plasticizer migration under EN 15777.