Polyether-grafted PDMS, 30–50 cP viscosity, hydrophobic silica nucleator, glycol carrier; spreads fast on aqueous foam.

MeFoam-PE Low-MW is a polyether-modified PDMS defoamer compound built on a low-molecular-weight (typically Mw 5,000–15,000 g/mol) PDMS backbone with polyether (polyethylene oxide / polypropylene oxide block) side chains grafted at 5–15 mol% of the methyl positions. SEMITECH supplies the active compound at 100% in glycol or water-glycol carrier, optionally pre-emulsified at 25–50% active in non-ionic surfactant for waterborne paint dosing. The compound includes 1–3% finely-divided hydrophobic silica as a nucleator (the silica particle initiates the foam-rupture mechanism by displacing surfactant molecules from the air-water interface) and antioxidant stabiliser at 0.05–0.1%.

The defining technical specification is viscosity: 30–50 cP at 25°C — substantially lower than the High-MW counterpart (Mw 30,000–80,000, viscosity 200–500 cP). The lower molecular weight means faster diffusion to the air-water interface in newly-formed foam, faster spreading across the bubble film, and faster bubble rupture — making MeFoam-PE Low-MW the choice when defoaming kinetics matter more than long-term anti-foam persistence. The polyether modification provides better wetting and emulsion stability in aqueous formulations than non-modified PDMS would, while the silicone backbone provides the surface-tension differential (typically 18–22 mN/m vs 35–60 mN/m for water-based foam) that drives the spreading mechanism.

Spreads on bubble film, displaces surfactant via lower surface tension, hydrophobic silica nucleates rupture.

Silicone defoamers operate by a three-step mechanism: (1) the defoamer droplet partitions to the air-water interface of foam bubbles, driven by its lower surface tension (~20 mN/m for polyether-PDMS vs 35–60 mN/m for typical aqueous foam); (2) the silicone phase spreads across the bubble film at high spreading coefficient, displacing the foam-stabilising surfactant from the interface; (3) hydrophobic silica particles in the spread silicone film nucleate bubble rupture by puncturing the thinning bubble wall. MeFoam-PE Low-MW is optimised for the spreading step — its low viscosity allows fast droplet break-up under shear and rapid migration to the air-water interface, with measurable foam-knockdown times of 5–15 seconds in standard 0.5% aqueous SDS surfactant solution at 25°C.

• Loading 0.05–0.15% — water-based coatings; clear-coat and pigmented architectural emulsions
• Loading 0.10–0.20% — flexographic and roto-gravure printing inks; food packaging
• Loading 0.15–0.30% — air-entrained construction (concrete admixture, cement-based grout)
• Loading 0.05–0.15% — adhesive emulsions (PVAc, EVA copolymer)

The trade-off is persistence: low-MW polyether defoamers re-disperse into the bulk over time as the spread film breaks up, requiring re-dosing at the latter stages of long production runs (>2 hours). For continuous-application persistence, switch to the High-MW counterpart MeFoam-PE High-MW, which forms a slower-spreading but more durable film. Typical practice in waterborne paint manufacturing: dose 0.10% MeFoam-PE Low-MW at the let-down stage for fast initial defoaming, then add 0.05% MeFoam-PE High-MW after 30 minutes for sustained anti-foam during shipping and end-use.

Water-based coatings (largest), printing inks, construction admixtures, polymer emulsions, water-treatment.

Water-based architectural and industrial coatings are the largest single application — emulsion paints (vinyl-acrylic, pure acrylic), waterborne wood coatings, anti-corrosive primer formulations. MeFoam-PE Low-MW at 0.05–0.15% on total formulation provides fast foam knockdown during high-shear let-down mixing without disrupting the dispersion stability of pigment grinds or the gloss of the dried film. The polyether modification provides better wetting on glass, plastic, and pre-painted substrates than non-modified silicone defoamers, which can cause crawling or fish-eyes on low-energy surfaces.

Flexographic and roto-gravure printing inks on paper and plastic film use MeFoam-PE Low-MW at 0.10–0.20% to suppress foam in the ink-circulation system between the fountain and the printing nip. Fast-acting kinetics is critical here because foam-bubble defects on the printed surface are immediate quality rejects; persistence matters less because ink is consumed within minutes of dosing. Air-entrained concrete admixtures and cement-based grout use MeFoam-PE Low-MW at 0.15–0.30% to control the entrained air content during high-shear mixing.

Polymer emulsion manufacture (PVAc, EVA, vinyl-acrylic copolymer) uses MeFoam-PE Low-MW at 0.05–0.15% during emulsion polymerisation to suppress reactor foam. Wastewater and process water treatment uses MeFoam-PE Low-MW at 50–500 ppm in plant-water systems where surfactant residues from upstream processes generate operational foam. Avoid for sustained anti-foam in long shipping/storage applications — for those, specify MeFoam-PE High-MW or MeFoam-S which provide longer-lasting persistence.

CoA per shipment; 25 kg HDPE pail; 12-month sealed shelf life; tolerates ambient handling; non-flammable.

SEMITECH issues a CoA on every batch with: viscosity at 25°C (Brookfield, target 30–50 cP), active silicone content (FT-IR or solvent extraction, target ≥98%), hydrophobic silica content (ash analysis after solvent extraction, target 1–3%), water content (Karl Fischer, target ≤0.5%), and visual appearance. Standard packing 25 kg HDPE pails for active compound; 200 kg HDPE drums for bulk paint plants; 50% emulsion form available in 25 kg HDPE jerrycans on request. MOQ 25 kg per grade. Lead time 1–2 weeks ex-Zhejiang to Asia ports, 4–6 weeks to Europe and North America after sea freight transit.

Storage: stable under ambient conditions; no nitrogen blanket required; non-flammable. Recommended: store sealed below 30°C in original packaging; freezing should be avoided (can break the silica-in-PDMS dispersion irreversibly, requiring re-grinding). Shelf life 12 months sealed for active compound; 6 months for emulsion form. Compatibility testing: small-batch trials are mandatory before production-scale dosing — silicone defoamers can interact with specific surfactants, biocides, and rheology modifiers in waterborne formulations to produce gel formation, surface defects, or premature defoamer separation. SEMITECH technical service provides starting-point formulations and compatibility-test protocols on request. REACH and regulatory: REACH-registered for industrial use; FDA 21 CFR 175.300 listed for indirect food-contact in printing-ink and packaging-coating applications. SDS in EU/GHS format issued with every shipment.

MeFoam-PE Low-MW is the fast-acting polyether defoamer — 30–50 cP viscosity for fast spreading and bubble rupture in water-based coatings, printing inks, and concrete admixtures. 0.05–0.3% loading. 5–15 sec foam knockdown in standard surfactant test. Pair with MeFoam-PE High-MW for production runs requiring sustained anti-foam persistence beyond 2 hours.

SEMITECH stocked grade; CoA per batch.