Emulsão CELVOLIT 1350 VAE para membranas impermeabilizantes flexíveis

CELVOLIT 1350 is a vinyl acetate-ethylene (VAE) copolymer emulsion designed as a primary binder for polymer-modified flexible waterproofing membranes, both one-component and two-component systems. The product is delivered at a nominal solids content of 55% with a Brookfield viscosity (spindle 3, 20 rpm) in the range of 500–1500 mPa·s, and a pH between 4.0 and 5.5. Its minimum film-forming temperature (MFFT) lies at 0 °C, a characteristic conferred by the ethylene comonomer that eliminates the need for external coalescents or phthalate plasticizers in most formulations. This ethylene modification also reduces the glass transition temperature (Tg) to approximately −15 °C, ensuring the cured membrane retains flexibility under low-temperature service conditions without additive migration. Unlike conventional vinyl acetate homopolymers or styrene-butadiene dispersions, Celvolit 1350 provides a balanced profile of wet substrate adhesion, alkali resistance, and crack-bridging elongation, as detailed in the subsequent sections.

What typical physical profile does Celvolit 1350 exhibit upon delivery?

The emulsion freezes below approximately −5 °C, causing irreversible coagulation; shipments exposed to sub-zero ambient must be quarantined and checked for grit content> 50 µm before use. Storage conditions exceeding 40 °C accelerate polyvinyl alcohol protective colloid hydrolysis, progressively raising viscosity and risking skin formation under headspace air.

When film formation and low-temperature flexibility become critical in below-grade waterproofing

Below-grade membrane applications require crack-bridging competence well below 0 °C while the substrate itself may be damp. Celvolit 1350, with its ethylene-enriched backbone, produces films exhibiting an ultimate elongation of >300% (ASTM D412, die C) even after 7 days of water immersion at 23 °C. Standard VAc homopolymer binders plasticized with DBP or DINP lose elongation owing to plasticizer leaching in permanent water contact, dropping to <100% elongation within 28 days; the internal plasticization of the VAE copolymer resists such deterioration. Low-temperature flexibility is evidenced by no cracking over a 2 mm mandrel at −25 °C (EN 14891:2017, clause 7.4.3). In cementitious two-component slurries, the emulsion maintains a stable pot life of 45–60 minutes at 23 °C when combined with an ordinary Portland cement-based powder blend, ensuring sufficient open time for trowel or roller application on vertical surfaces.

Shear stability and the risk of grit formation during high-speed dispersion

Incorporation of coarse fillers and cement powders places high mechanical stress on the polymer particles. In production lines using twin-shaft high-speed dispersers with a peripheral speed exceeding 18 m/s, the emulsion may undergo shear-induced coagulation if the protecting colloid layer is insufficiently anchored. Celvolit 1350 is stabilized with a medium-high molecular weight PVOH, providing shear resistance up to 30,000 mPa·s paste viscosity before significant grit generation (> 100 µm particles) appears. However, when compounding with aggregates of Mohs hardness >4 (quartz sand), the dispersion must be introduced after filler wetting and the mixer speed reduced below 12 m/s to avoid localized temperature spikes above 35 °C that initiate particle destabilization. Defoamer choice becomes critical: polyether-modified polysiloxanes at 0.3–0.5% by total batch weight maintain air release without surface cratering, while mineral oil-based defoamers have been observed to coalesce the VAE particles prematurely, forming hydrophobic microgels that reduce film tensile strength by up to 20%.

Without an explicit header, the following processing sequence represents a best-practice integration protocol for one-component flexible slurry membranes. Pre-mix cement, cellulose ether (0.5–1.5 wt% of total powder), and a retarder such as tartaric acid (0.1–0.3 wt%). Add water and Celvolit 1350 in a mass ratio adjusted to achieve a water-to-cement ratio of 0.35–0.40. Mix with a slow-speed planetary mixer for 90 seconds, scrape sides, then continue mixing for another 60 seconds. Do not exceed 500 rpm under air. Coating thickness per layer is limited to 1.0 mm wet to prevent mud-cracking during drying at relative humidity below 50%. Drying time between coats is 4–6 hours at 20 °C/65% RH; forced-air drying above 30 °C can entrap moisture, leading to interfacial blistering when a second layer is applied.

Advantages of VAE over acrylic and SBR latexes in one-component cementitious membranes

Acrylic dispersions, though offering excellent UV resistance in above-grade applications, suffer from saponification in the alkaline cement environment (pH >12), evidenced by a reduction in tensile strength of up to 35% after 28 days of alkali immersion (ASTM C109, 5% NaOH). SBR latexes typically require a high surfactant loading, which increases water absorption and reduces adhesion to damp substrates; peel adhesion values on concrete (EN 1015-12) commonly fall below 0.5 N/mm² after 24 hours water saturation. Celvolit 1350, tested in an identical cement-rich formulation (cement: sand ratio 1:2.5), delivers water absorption of <4% (EN 1062-3) and adhesion strength> 1.2 N/mm² to primed concrete after 7 days immersion. The data below compares three binder types at equal polymer-cement ratio (0.10 by mass).

The internal plasticization of the VAE chain continues to dominate these comparisons: no external ester plasticizer is incorporated, thus no leaching-driven property loss occurs. In contrast, the SBR system exhibits higher residual odor and limited alkaline saponification resistance due to butadiene unsaturation, while the acrylic must be heavily formulated with coalescents that lower the modulus under heat aging.

In two-component cementitious waterproofing intended for potable water contact, Celvolit 1350 conforms to the migration limits of EN 14944-2 and is listed under component formulations evaluated per the French Avis Technique framework. For applications where membrane thickness exceeds 3 mm dry film, cement content must be adjusted to compensate for shrinkage: a cement-to-aggregate ratio of 1:3 with a polymer-cement ratio of 0.12 prevents early shrinkage cracking observed in thin films dried under wind velocity >2 m/s. Published data for installations directly over expanded polystyrene insulation boards is limited; preliminary pull-off tests indicate that a water-based epoxy primer interlayer becomes necessary to prevent debonding above 0.8 N/mm².

When incompatibility with amine accelerators determines formulation boundaries

The vinyl acetate component is susceptible to alkaline hydrolysis, accelerated by constituents that elevate the pH above 11 prematurely. Consequently, amine-based set accelerators—such as diethanolamine or triethylenetetramine—must be strictly excluded from the liquid portion. Their addition, even at 0.1 wt% on cement, can reduce the pot life to under 10 minutes and generate a strong acetic acid odor, indicating saponification. Instead, calcium formate at 0.5–1.5 wt% provides a compatible acceleration pathway. Similarly, certain bacteriostats based on isothiazolinones accelerate polymer destabilization below pH 3.5, mandating buffer adjustment to maintain the system above pH 4.0 during storage. Published data for this specific configuration is limited regarding long-term hydrolysis under permanent submerged use in swimming pools where chlorine residuals exceed 3 ppm; periodic film hardness checks via Shore A durometer (ISO 868) are advised.