| HS Code | 385261 |
| Appearance | White free-flowing powder |
| Solid Content Wt | 99.0 ± 1.0 |
| Bulk Density G L | 400 - 600 |
| Particle Size μm | 80 - 120 |
| Ph Value 10 Aqueous Dispersion | 6.0 - 8.0 |
| Ash Content Wt | 10 - 15 |
| Minimum Film Formation Temperature C | 0 - 5 |
| Tensile Adhesion Strength Mpa | ≥ 1.5 (after 28 days) |
| Water Resistance | Excellent, with low water uptake |
| Hydrophobicity | Highly hydrophobic due to silicone modification |
| Freeze Thaw Stability | Improved versus standard VAc-acrylate RDP |
| Re Dispersibility | Forms stable dispersion with good fluidity |
As an accredited Silicone-modified VAc-Acrylate RDP factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Silicone-modified VAc-Acrylate RDP is supplied in 25 kg laminated kraft bags with PE liners, palletized and shrink-wrapped. |
| Container Loading (20′ FCL) | Loading 20′ FCL: secure palletized bags of silicone-modified VAc-Acrylate RDP, ensuring dry, ventilated, and stable stowage. |
| Shipping | Silicone-modified VAc-Acrylate RDP is shipped as a free-flowing powder in moisture-proof laminated bags or drums, palletized and wrapped. Keep dry, cool, and ventilated during transport. Avoid excessive humidity and direct sunlight. Handle gently to prevent bag damage. Not classified as hazardous under standard shipping regulations. |
| Storage | Store in a cool, dry environment below 25°C with low humidity. Keep the container tightly sealed to prevent moisture absorption and caking. Avoid exposure to direct sunlight and extreme temperatures. Use within the recommended shelf life, typically 6–12 months, to maintain redispersibility and performance. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored unopened in cool, dry conditions and protected from moisture. |
In production-scale cementitious tile adhesive development, silicone-modified VAc-acrylate redispersible polymer powder is introduced into a C2 baseline mix composed of 32.0 wt% CEM I 52.5 R, 61.5 wt% graded silica sand with a 0.1–0.5 mm cut, 0.35 wt% cellulose ether, 0.10 wt% calcium formate, and RDP dosage varied from 2.0–4.5 wt% relative to total dry mass. Dispersion is carried out in a segmented twin-shaft compulsory mixer operating initially at 140 rpm for 3 min and then at 250 rpm for 7 min; the silicone-bearing latex film redisperses at mixing-water pH 11–13 but requires longer wetting than an unmodified VAc-acrylate powder, particularly when the powder is charged directly into the water phase before cement. Reverse charging into the sand fraction reduces hydrophobic particle agglomeration. The siloxane functionality lowers film surface energy after coalescence, improving adhesion to dense porcelain and low-absorption vitreous tile bodies while maintaining the deformability classified under EN 12002:2008 as S1 or S2 depending on dosage and acrylic monomer ratio. Formulation work targeting C2TES1 must reconcile two conflicting mechanisms: the hydrophobic film reduces water ingress after immersion conditioning, but overdosing above 4.5 wt% introduces entrained air above 8 vol% and can delay early cement hydration sufficiently to reduce 7-day pull-off strength on low-porosity substrates. Production trials on 500 kg twin-shaft mixers have shown that adding the silicone-modified powder after the cellulose ether has been dispersed eliminates lumping and lowers batch-to-batch wet density variation to below ±3%. The powder moisture content should be kept below 1.0 wt% before blending; at higher residual moisture the hydrophobic treatment can re-agglomerate in silo storage and create dosing screw clogging on continuous dry-mix plants.
| Conditioning regime | Test method | C1 minimum | C2 minimum |
|---|---|---|---|
| 28 d dry storage at 23 °C, 50 % RH | EN 1348 | 0.5 N/mm² | 1.0 N/mm² |
| Water immersion after 7 d dry and 21 d immersion | EN 1348 | 0.5 N/mm² | 1.0 N/mm² |
| Heat ageing after 14 d dry at 70 °C | EN 1348 | 0.5 N/mm² | 1.0 N/mm² |
| Freeze-thaw cycles per scheme defined in EN 12004:2017 | EN 1348 | 0.5 N/mm² | 1.0 N/mm² |
The C2TES1 designation adds extended open time and improved slip resistance to the same adhesive class. Open-time verification under EN 1346 requires pull-off after 30 min at ≥0.5 N/mm², while slip resistance measured in accordance with EN 1308 must remain below 0.5 mm. Silicone-modified VAc-acrylate RDP alters open-time behaviour differently from unmodified acrylic powders because the hydrophobic film retards water evaporation from the trowelled adhesive bed without plasticising the cementitious matrix excessively. At 2.5 wt% dosage, open-time retention is improved under air movement of 0.5 m/s and 23 °C, but below 2.0 wt% the effect is indistinguishable from a standard VAc-acrylate powder in most production mixes. The material is incompatible with high-charge-density polycarboxylate superplasticizers when dosed above 0.5 wt% of total dry mix because dispersant adsorption onto the hydrophobic particle surface can produce rapid slump loss and uneven film formation. Published data for this specific silicone-modified configuration in C2TES1 formulations is limited outside manufacturer technical bulletins and interlaboratory comparison reports.
The ETICS base coat and bedding mortar segment requires a different balance of film formation, hydrophobicity and water-vapour permeability. A formulation loaded at 2.5–4.0 wt% with silicone-modified VAc-acrylate RDP is typically dispersed in a plowshare mixer at 95 rpm in 700 kg batches, followed by bagging under conditioned air at 35 % RH. The silicone modification reduces capillary water absorption of the cured mortar while leaving sufficient continuous polymer interface around redispersed latex particles to permit water-vapour diffusion under the criteria of EN ISO 7783 and liquid-water absorption under EN 1062-3. In ETICS base coats applied over expanded polystyrene or mineral-wool insulation board, the powder must be combined with an alkali-resistant glass-fibre mesh and a fine filler with a maximum particle size below 0.7 mm; coarser aggregate tears the insulation during notch-trowel application and causes local thinning of the base coat below the 3.0 mm minimum wet-film thickness. The hydrophobic film develops over 48–96 h at 20 °C and 65 % RH; early exposure to rain can wash out silicone-rich fines and create surface pinholes that later reduce pull-off adhesion on the thermal-insulation board. Production experience on full-scale facade trials has shown that overdosing above 4.5 wt% reduces the tack required for mesh embedment and can produce a sliding failure at the insulation interface during curing under direct solar exposure. In addition, the powder should not be combined with amine-based additives in the same blend because amino-functional silanes can trigger premature crosslinking and reduce redispersibility in the mixing water. For legacy approvals under ETAG 004 and current harmonised assessment under EAD 040083-00-0404, the exact base-coat formulation must be tested with the specific insulation substrate and finishing layer; no generic single-powder dosage can substitute for system-level verification.
In slurry membrane production, silicone-modified VAc-acrylate RDP is used at 3.0–5.0 wt% of the dry component to produce flexible one-component or two-component cementitious waterproofing layers with enhanced water repellency after hardening. The dry base is mixed in a high-shear vertical mixer at 350 rpm before the liquid polymer is added, because the hydrophobic powder tends to float on low-viscosity liquid-resin phases if added directly. After mixing, the slurry is applied at a wet-film thickness of 1.5–2.5 mm using a notched trowel or spray equipment with a 4.0 mm nozzle orifice. Crack-bridging capacity is governed not only by polymer dosage but also by film continuity across the cementitious matrix; the silicone modification lowers surface tension at the film-water interface, which improves adhesion to damp vertical concrete but can also make the fresh membrane sensitive to overmixing. Extended mixing above 5 min at 600 rpm destabilises the air voids and can reduce crack-bridging values measured under EN 14891:2017. The relevant standard recognises different water-impermeability and crack-bridging classes for cementitious slurry products under ceramic tiling; a specific formulation can be classified as CM-O1 or CM-O2 only after full testing with the selected tile adhesive and grout system. Published data for this specific silicone-modified VAc-acrylate configuration in slab-test comparisons is limited; the available manufacturer data indicate that crack-bridging at low temperature depends more on the acrylic backbone than on the siloxane content. Substrate preparation remains a controlling variable. Concrete surfaces with laitance, mould oil or release-agent residue must be prepared to a minimum surface tension of 38 mN/m before application, because the hydrophobic membrane will not wet grease-contaminated areas and pinhole defects can appear within 24 h of curing. The powder is also incompatible with high-calcium-aluminate cement blends where early ettringite formation is rapid, because the silicone film slows water availability at the hydration front and produces a brittle interface at the bond line.
Underlayment formulation screening begins with flow-retention conflicts introduced by hydrophobized powders. Silicone-modified VAc-acrylate RDP raises low-shear viscosity and slows coalescence in self-leveling cementitious systems, which can either extend flow cone spread when water demand is optimised or create a sticky, stiff paste if the powder dosage exceeds the capacity of the available wetting water. The powder is dry-blended with sulphoaluminate or calcium-sulphate-modified Portland cement, fine silica sand with a 0.1–0.3 mm cut, accelerating agents and carboxylic-ether-based plasticisers; the RDP dosage is normally held at 3.0–5.0 wt%. Mixing for site application uses a forced-action mixer at 400–500 rpm for 2–3 min, followed by a maturation period of 3–5 min. Flow spread is measured in accordance with EN 12706 at 5 min and 20 min after mixing; the silicone modification can improve 20 min flow retention because the hydrophobic film reduces free-water evaporation from the surface, but excessive air entrainment above 5 vol% produces a surface defect known as micro-foaming that cannot be removed by pin rolling. Underlayment shrinkage is evaluated under ASTM C157/C157M-22 or the equivalent supplier-specific corrugated-tube method; the polymer film redistributes drying shrinkage and reduces edge curling on gypsum and steel substrates. Production experience on continuous mixing pumps fitted with rotor-stator stators has shown that the powder must be pre-dispersed before entering the pump at high shear, otherwise hydrophobic agglomerates accumulate at the stator inlet and reduce throughput by 10–15 % over a 60 min run. Published data for this specific silicone-modified VAc-acrylate configuration in self-leveling underlayments is limited; the available technical reports concentrate on standard VAc-acrylate systems and do not provide a full statistical basis for flow cone or shrinkage values across different cement bases. When the powder is used at dosages above 5.0 wt%, compressive strength measured by ASTM C109/C109M-21 can fall below 20 N/mm² at 28 d in high-flow formulations, which restricts use in load-bearing underlayment specifications requiring 25 N/mm² or higher.
Repair mortars formulated to EN 1504-3 classes R3 and R4 use silicone-modified VAc-acrylate RDP at 2.5–5.0 wt% to reduce capillary water uptake, improve bond strength and maintain a lower dynamic elastic modulus than unmodified acrylic powder at equal dosage. The polymer is dry-blended with low-alkali cement, silica fume or metakaolin, washed aggregate with a maximum particle size of 2.0 mm, shrinkage-compensating additive and powdered defoamer. Mixer selection affects performance more than in tile adhesives because repair mortars have a longer workability window of 30–45 min and are placed on prepared concrete with a minimum substrate pull-off strength of 1.5 N/mm². A twin-shaft compulsory mixer with 250 kg batch capacity and 150–200 rpm shear rate is sufficient to disperse the hydrophobic powder without overmixing. Bond strength is tested by pull-off in accordance with EN 1542; class R4 requires ≥2.0 N/mm² on standard concrete, while class R3 requires ≥1.5 N/mm². Compressive strength is measured under EN 12190, with R4 requiring ≥45 N/mm² and R3 requiring ≥25 N/mm². The silicone modification improves resistance to water ingress measured under EN 13057 and chloride-ion penetration measured under EN 13396, but it also delays film formation at low ambient temperatures. Below +5 °C, coalescence is slowed and the mortar may appear dry, leading applicators to add water beyond the specified maximum water-to-powder ratio of 0.16–0.18; this extra water produces bleed channels and reduces final adhesion. The material should not be combined with excess calcium nitrite accelerator above 2.0 wt% of cement weight because the high ionic strength can destabilise the redispersed latex and create localised hard spots in the cured repair layer. Published data for this specific silicone-modified configuration used as a full R4 repair mortar is limited; manufacturer technical bulletins provide comparative bond and shrinkage data against unmodified VAc-acrylate powder but do not cover all substrate classes defined in EN 1504-3.
Joint filler manufacturing lines running gypsum-based dry mixes rarely tolerate hydrophobic film development above the substrate surface. For this application, silicone-modified VAc-acrylate RDP is used at 1.0–2.0 wt% in combination with dispersible starch, cellulose ether and calcium carbonate filler. The mortar is mixed in a horizontal ribbon blender at 70 rpm for 8 min; the silicone-modified powder reduces powder dustiness in bag filling but can produce water beading on the trowelled surface above 2.0 wt%. The resulting film must remain compatible with water-based primer and paint systems; if the hydrophobic powder content is too high, paint delamination can occur under cross-cut testing. The governing standard for ready-mixed joint compounds is ASTM C475/C475M-17(2022), while field performance is verified by joint-cracking resistance and surface bonding under the applicable local specification. This is a shallow formulation zone because the technical requirements are well established and the siloxane modification mainly affects surface wetting rather than core joint durability.
For conventional cementitious tile grouts supplied under EN 13888 CG2 designation, dry blending of 1.0–2.0 wt% silicone-modified VAc-acrylate RDP into the cement/sand/pigment premix is sufficient to reduce surface water absorption without altering the joint compressive strength.
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Commercial silicone-modified vinyl acetate–acrylate redispersible polymer powder (RDP) is produced by spray drying of an aqueous copolymer dispersion containing vinyl acetate, acrylic ester, and a silicone-functional monomer or silane-grafted intermediate. The resulting free-flowing powder is intended for dry-mix cementitious and gypsum-bound compounds where the silicone functionality contributes reduced long-term water uptake, improved wet adhesion, and higher tensile strength retention after water immersion relative to conventional vinyl acetate–ethylene and unmodified vinyl acetate–acrylate copolymers. Because the product is dry-blended into mortar formulations, its redispersibility, bulk density, and anti-caking surface treatment are manufacturing-critical parameters.
Model nomenclature is not harmonized across producers. Technical data sheets typically encode nominal silicone modification level, minimum film-forming temperature class, and anti-caking mineral type. A representative grade designation may appear as SMVAc/A-S25-08, where 25 denotes a nominal silicone monomer content of 2.5 wt% on polymer solids and 08 denotes a supplier-specific MFFT class; the code is illustrative and must be verified against the mill certificate.
Release testing for a lot should include bulk density, sieve residue, residual moisture, ash content, dispersion pH, minimum film-forming temperature, and glass transition temperature. The specification envelope below is compiled from publicly available technical data sheets and is not a procurement limit.
| Parameter | Typical envelope | Test method |
|---|---|---|
| Appearance | Off-white to pale yellow free-flowing powder | Visual inspection |
| Bulk density | 350–550 g/L | ASTM D1895 Method A |
| Residual moisture | ≤1.5 wt% | ASTM E203 Karl Fischer |
| Ash content after combustion | 8–15 wt% | ASTM D5630 or ISO 3451-1 |
| pH, 10% dispersion | 6.5–9.0 | ISO 976 |
| Minimum film-forming temperature | 0–12°C | ISO 2115 |
| Glass transition temperature | −5°C to +10°C | ISO 11357-2 |
| Sieve residue > 250 µm | ≤1.0% | ISO 1624 |
Ash content should not be interpreted as a direct measure of silicone content because mineral anti-blocking agents such as kaolin or silica contribute to ignition residue. Silicone monomer content is normally confirmed by FTIR or ICP after acid digestion; published data for specific commercial grades is limited. Differential scanning calorimetry under ISO 11357-2 should be performed on the dry powder after a first heating cycle to erase thermal history. The reported glass transition is typically a single step, but a weak secondary transition between 30–50°C may indicate silicone-rich domains; this should not be confused with melting of the anti-caking mineral.
Redispersibility and particle size after dispersion are monitored because spray-dried powder that does not return to primary latex particles loses film-forming efficiency. Laser diffraction after gentle stirring in deionized water typically shows a median particle size of 1–10 µm; values above 20 µm indicate partial coagulation or moisture damage. The redispersed dispersion at 50% solids may be checked by Brookfield viscosity at 20°C and 60 rpm under ISO 2555, but viscosity is not a universal specification because surfactant type and anti-caking mineral alter the rheological profile. Minimum film-forming temperature is critical for cold-weather application. When substrate temperature is less than 3°C above the measured MFFT, coalescence may be incomplete, leading to discontinuous polymer films and reduced adhesion. In practice, the powder is not recommended for application below 5°C substrate temperature unless formulation adjustments are validated by EN 1348 after curing.
In C2 cementitious tile adhesives classified by EN 12004-1, the powder is commonly dosed at 1.5–4.0 wt% of total dry mix. At dosages below 1.0 wt%, the polymer film is discontinuous and water immersion tensile adhesion under EN 1348 may fall below 1.0 N/mm², particularly on dense concrete or gypsum board. At dosages above 5.0 wt%, early compressive strength can decline because the polymer phase retards cement hydration and increases air entrainment. The processing window is therefore narrow, often ±0.5 wt% around an optimized set point for a specific cement and cellulose ether system.
In external thermal insulation composite systems, the powder is specified where the base coat must retain tensile adhesion after water immersion and freeze–thaw cycling. The silicone-modified VAc-acrylate RDP reduces capillary water transport through the base coat while maintaining water-vapour diffusion, as evaluated by EN 1015-18 and EN 12086 respectively. Typical addition in ETICS base coats is 2.5–4.5 wt%; the exact dose is determined by tensile adhesion to insulation board under EAD 040083 and by impact resistance testing. Published data for specific commercial grades is limited, so formulation trials should include 28 d dry cure followed by 7 d water immersion.
Three polymer classes are commonly encountered: vinyl acetate–ethylene, pure acrylic, and silicone-modified VAc-acrylate. Unmodified VAE powders have lower raw material cost but can undergo saponification in cement pore solution above pH 12.5; the acetate group is hydrolyzed, reducing molecular weight and wet adhesion. Pure acrylic powders provide better UV stability and alkali resistance but generally require higher polymer loading or cost. Silicone-modified VAc-acrylate powders incorporate siloxane or silane functionality on an acrylate-containing backbone; the acrylate units reduce alkali hydrolysis compared with VAE, and the silicone functionality lowers surface energy and improves wet adhesion to low-energy substrates such as glazed tile, metal, and insulation board.
| Polymer class | Backbone chemistry | Behaviour in alkaline cement | Water uptake tendency | Typical C2 tile adhesive dosage | Primary adhesion standard |
|---|---|---|---|---|---|
| Unmodified VAE | Vinyl acetate–ethylene | Saponification possible above pH 12.5 | Higher | 1.5–4.0 wt% | EN 1348 |
| Silicone-modified VAc-acrylate | Vinyl acetate–acrylate–siloxane/silane | Improved resistance due to acrylate and siloxane | Reduced capillary uptake | 1.5–4.0 wt% | EN 1348 |
| Pure acrylic | Acrylic ester copolymer | Good alkali resistance | Moderate | 1.0–3.5 wt% | EN 1348 |
The practical distinction is measured by tensile adhesion retention after water immersion. Silicone-modified VAc-acrylate RDP shows higher retention of EN 1348 tensile adhesion than unmodified VAE at equal polymer loading in most Portland cement systems, but the magnitude depends on cement type, water-to-cement ratio, and curing age. Styrene–butadiene rubber powders are selected where high elongation and low-temperature crack bridging dominate; they generally show lower UV resistance and different mortar rheology. Silicone-modified VAc-acrylate RDP is chosen when a balance of cement compatibility, wet adhesion, and hydrophobic behaviour is required rather than maximum elongation.
In polymer-modified structural repair mortars specified under EN 1504-3 class R4, the powder is added at 2.0–3.5 wt% to reduce permeability and improve bond to concrete. The silicone-modified grade is relevant where the repaired element is exposed to frequent wetting and de-icing salts. Bond strength is measured by EN 1542 after conditioning; chloride ion content and compatibility with reinforcing steel must be verified according to EN 1504-3 requirements. Published data for this specific configuration is limited; trials should include adhesion after wet/dry cycling and carbonation resistance.
Flexible cementitious waterproofing slurries tested under EN 14891 use the powder to lower capillary water uptake while retaining crack-bridging capacity. The silicone modification contributes to water repellency but does not close the system to water-vapour diffusion; this is important for moisture balance in damp substrates. Dosage is normally 2.0–4.0 wt% depending on cement content and crack-bridging class.
Storage life is governed by moisture uptake and anti-caking performance. At relative humidity above 60%, the powder should remain in sealed containers or be conditioned before use; moisture uptake above 1.5 wt% reduces redispersibility and can cause bridging in screw conveyors and hopper outlets. Storage temperature should be below 30°C because elevated temperatures accelerate sintering of the polymer particles and reduce MFFT stability.
Incompatibilities include amine-based additives that release ammonia during storage; the resulting alkaline microenvironment can hydrolyze vinyl acetate groups and accelerate silanol condensation, producing granules that no longer fully redisperse. The powder should not be dry-blended with high-alkali accelerators in an open mixer for extended periods. Any formulation change must be validated by EN 1348 tensile adhesion after water immersion and by ISO 1624 sieve residue on the dry blend.
