Section
| HS Code | 903187 |
| Chemical Family | Silicone-polyether hybrid |
| Physical Form | Liquid |
| Appearance | Clear to slightly hazy viscous liquid |
| Active Content | 100% |
| Viscosity At 25 C | 800-1500 mPa·s |
| Specific Gravity At 25 C | 1.00-1.03 |
| Ph 1 Aqueous Dispersion | 4.0-6.0 |
| Water Dispersibility | Self-dispersing in water |
| Flash Point | >100°C |
| Storage Stability | 12 months if stored in original sealed containers |
| Freezing Point | <0°C |
| Ionic Character | Non-ionic |
As an accredited SILFOAM SD 8260 Silicone-Polyether Hybrid Self-Dispersing Antifoam factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 200 kg drums, SILFOAM SD 8260 is a silicone-polyether hybrid self-dispersing antifoam for efficient foam control. |
| Container Loading (20′ FCL) | 20′ FCL containerized shipment of SILFOAM SD 8260 silicone-polyether antifoam, securely packed in drums on pallets for safe transport. |
| Shipping | Ship in original sealed containers, dry and covered, upright to prevent leakage. Protect from freezing, excess heat, and direct sunlight. No dangerous goods classification; however, follow standard chemical transport protocols, secure loads, and have spill containment available. Avoid contact with strong oxidizers during transit. |
| Storage | Store SILFOAM SD 8260 in its original, tightly sealed container in a cool, dry, well-ventilated area. Avoid direct sunlight, excessive heat, and freezing temperatures, as these can destabilize the product. Keep away from incompatible materials. Under recommended conditions, the product typically retains effectiveness within its stated shelf life. |
| Shelf Life | SILFOAM SD 8260 has a shelf life of 12 months from manufacture when stored in original, unopened containers below 25°C. |
In tinted waterborne wall paint production, foam introduced during high-speed dispersion of titanium dioxide and extender pigments can survive into the low-shear letdown phase and generate cratering in satin and semi-gloss topcoats. A split addition of SILFOAM SD 8260 at 0.05–0.25 wt% of total batch mass is applied: half is charged during pigment dispersion with a Cowles dissolver at 18–22 m/s tip speed, and the remainder is added after binder letdown at 25–35°C under a sawtooth agitator speed of 300–500 rpm. This sequence controls both macrofoam generated by air incorporation in the millbase and microfoam stabilized by associative rheology modifiers. For a styrene-acrylic interior wall paint at 95–105 KU Stormer viscosity, the recommended screening range should be validated by fineness of grind according to ISO 1524, specular gloss at 20° and 60° according to ISO 2813, and wet scrub resistance according to ASTM D6736. Addition above 0.30 wt% can produce visible cratering in high-gloss acrylic tint bases because excess siloxane-polyether copolymer migrates to the air–liquid interface and lowers dynamic surface tension below the level required for substrate wetting.
In tinted formulations, the product must be evaluated with each colorant system, particularly high-load phthalocyanine blue and carbon black bases, because colorant surfactants can reduce antifoam efficiency and prolong foam break time. On production-scale batches of 1,000–10,000 kg, the most effective point of final addition is after coalescing solvent and ammonia neutralization are homogeneously distributed, but before the last increments of cellulose-ether thickener solution are incorporated. At this stage, low-shear viscosity is sufficiently developed to avoid separation, while the defoamer can still migrate to entrained air nuclei. The treated batches are used for interior matt emulsion, washable wall paint, and tintable ceiling white; in each case, the final film is checked through a 100 µm wet-film drawdown bar on black-coated chart paper to detect surface defects before filling into retail containers.
Foam in water-based flexographic inks does not collapse readily in the return line because the ink circulation pump repeatedly re-entrains air at the chambered doctor blade, at the anilox roll nip, and during turbulent fall from the return tray. In a central-impression press running at 250–350 m/min with anilox rolls of 300–500 l/cm and viscosity held at 18–25 s in a 4 mm DIN cup at 23°C, the foam layer can alter ink transfer density and produce mottling in halftone areas. SILFOAM SD 8260 is introduced into the finished ink letdown at 0.1–0.3 wt%, preferably as a 1:1 dilution in deionized water under slow agitation to avoid localized solvent shock. The self-dispersing silicone-polyether hybrid distributes into acrylic resin solution systems at pH 8.5–9.5 without forming visible stringers or plate-out, as assessed by a 25 µm drawdown on clear glass under transmitted light. The preferred injection point is after the ink has passed through the final filter and before pH adjustment with monoethanolamine or dimethylethanolamine. Foam suppression is evaluated on-press by measuring halftone dot gain against the digital proof and by checking ink density with an inline densitometer; acceptable variation is normally within ±0.05 density units. Over-addition above 0.5 wt% can reduce adhesion on corona-treated polyethylene film and should not be used without side-by-side tape adhesion testing according to ASTM D3359. Inks formulated for food-contact printed packaging require confirmation of transfer levels under EU 10/2011 or FDA 21 CFR 176.170 depending on the substrate; published data for this specific hybrid in lamination inks is limited, so a migration study on the finished print is required when direct food contact is declared.
Pressure-sensitive adhesive coating lines generate microfoam through recirculating shallow reservoirs, slotted pumping, and high-shear slot-die geometry. In waterborne acrylic PSA with solids of 50–65 wt% and Brookfield LV viscosity of 200–3,000 mPa·s at 12 rpm, entrained air causes die-lip build-up, coat-weight fluctuation, and skipped lanes on silicone release liner at machine speeds of 80–250 m/min. SILFOAM SD 8260 is added at 0.05–0.20 wt% of wet adhesive mass after the final pH adjustment and before the last viscosity correction; the low addition level is used first because silicone-polyether hybrids can reduce quick-stick properties if the free polydimethylsiloxane fraction migrates to the adhesive–release-liner interface. Peel adhesion is checked according to ASTM D3330 at 180° peel and 300 mm/min crosshead speed, loop tack is measured by FINAT FTM 9, and static shear on stainless steel is evaluated by FINAT FTM 8 at 23°C and 50% RH. The coating line is typically fitted with a slot die gap of 50–150 µm, an infrared drying tunnel of 25–40 m length, and in-line coat-weight scanning at 2–4 m intervals. Because the antifoam is self-dispersing, it can be pre-diluted with the emulsion base at 1:2 and metered through a dosing skid into the recirculation trough; shear conditions in a rotary lobe pump of 1,500 rpm are sufficient to distribute the additive without generating new foam. In transfer coating, the treated adhesive must be evaluated for film clarity and anchorage to 12 µm polyester or 36 µm cast polypropylene substrate; any reduction in coat-weight uniformity below ±1.0 g/m² at a 21 g/m² target is regarded as out of specification. Published data for this specific configuration is limited for high-speed transfer coating above 250 m/min; therefore pilot trials with in-line foam monitoring are required before committed production.
At high-pressure through-tool coolant delivery of 70–150 bar, air entrainment is mechanically induced at the tool–workpiece interface and is returned to the central sump as a pseudo-stable foam layer. Sump circuits with capacities of 2,000–10,000 L and circulation rates of 200–500 L/min often suffer pump cavitation and level-sensor failure when macrofoam exceeds 20–30 cm height above the liquid surface. SILFOAM SD 8260 is incorporated into the coolant concentrate at 0.05–0.20 wt% before the emulsification stage, then additionally post-added at 0.01–0.05 wt% into the working emulsion if dynamic foam persists after 8 h of high-throughput milling. The self-dispersing character permits dosing directly into the sump return weir where turbulence from the return line distributes the additive; a dosing rate of 10–30 mL/min for a 5,000 L sump is used during trial runs. Emulsion stability is monitored through visual creaming after 24 h in a 100 mL graduated cylinder and through oil droplet size analysis using laser diffraction according to ISO 13320-1. Foam generation in the coolant is measured by the bottle shake test at 1,000 rpm for 60 s according to ASTM D3601, with acceptable foam collapse to <10 mL after 60 s standing. The additive is designed to resist precipitation in hard water up to 200 ppm CaCO₃ hardness, but field data for highly chelated synthetic coolants containing high levels of glycol ethers are limited. Continuous filtration through 5–10 µm bag or cartridge elements may remove some dispersed antifoam droplets over a 24–48 h period, necessitating make-up dosing. For operations where parts are subsequently powder coated, the cleaned metal surface must be assessed for silicone transfer; a water-break-free check according to ASTM F22 is recommended before pretreatment and coating.
Vacuum distillation of residual monomer from carboxylated styrene/acrylic latex batches is a critical point for foam collapse because anionic surfactant loadings of 1.5–3.0 wt% on monomer and high-viscosity shear-thinning behavior generate stable macrofoam. In a jacketed stainless steel reactor of 10–30 m³, the latex is cooled to 45–60°C before post-polymerization additive charging, and residual monomer stripping is performed at 150–250 mbar absolute. SILFOAM SD 8260 is added at 0.05–0.15 wt% of wet latex mass after the polymerization short-stop and before vacuum is applied; the self-dispersing silicone-polyether hybrid suppresses foam that would otherwise fill the overhead condenser and contaminate recovered monomer. The additive must be introduced under gentle agitation at 20–40 rpm in a 2–4 m³ vessel, because high shear during addition can create a secondary microfoam population that persists through vacuum. Process operators measure coagulum on a 45 µm sieve according to ISO 4576; the target is <0.05 wt% of total latex solids after stripping. The defoamer is evaluated for influence on minimum film-forming temperature and on particle size distribution measured by ISO 22412. The stripped latex is used in construction adhesives, caulks, nonwoven binders, and exterior masonry paints. When the latex contains high levels of associative thickener or post-added wetting agent, the antifoam may partition into the aqueous phase and lose efficiency over 7–14 days of storage; therefore, a batch-specific ageing test at 50°C for 14 days is required before large-volume commitment. Published data for this specific configuration is limited for vinyl-acetate-ethylene lattices above 70 wt% solids, because those systems typically require a stronger organomodified polysiloxane with hydrophobic silica.
Spray washer tanks charged with 10–12 pH alkaline cleaner develop a dense foam layer if the free caustic concentration exceeds 2.0 g/L and the bath contains emulsified soil loadings above 0.5 g/L. In a continuous belt washer with spray pressure of 3–5 bar and nozzle diameters of 1.5–2.5 mm, the foam layer obstructs spray impingement and can trigger low-level alarms. SILFOAM SD 8260 is post-added as a 1:10 aqueous dilution into the wash stage at 0.01–0.10 g/L of working bath volume, using a metering pump at the suction side of the recirculation pump. The diluted product disperses spontaneously and has a short induction period of 2–5 min for foam control under the mechanical energy of the washer. Because the silicone-polyether hybrid is exposed to alkaline hydrolysis, long-term stability is greatest at pH 10–11 and bath temperature 40–60°C; operation above pH 12.5 or above 70°C can reduce effective service life to 8–12 h, making continuous low-rate addition more reliable than single-shot dosing. The wash bath is filtered through 50–75 µm media or hydrocyclone separation to reduce suspended solids and prevent antifoam droplet adsorption onto oil emulsification agglomerates. Treated steel, aluminum, and zinc-coated strip are subsequently tested for coating adhesion using ASTM D3359 after e-coat or powder application; because silicone-polyether hybrids can remain on the surface if not adequately rinsed, a final 45–55°C deionized-water rinse stage with 0.5–1.0 bar spray pressure is recommended. In a six-stage automotive parts washer processing 3,000–5,000 kg/h of stamped steel components, the post-add point is the second rinse-to-wash return weir, where recirculation rate is highest and foam collapse can be observed within one residence time of the tank.
Suspension concentrate milling in a horizontal bead mill introduces finely dispersed air into aqueous slurries that contain 300–500 g/L active ingredient, nonionic and anionic surfactants, glycols, and electrolyte salts. Foam in an SC formulation is not merely a filling problem; it can reduce the effective mill chamber fill and lower the grinding efficiency of 0.6–1.0 mm zirconia beads at agitator tip speeds of 10–14 m/s. SILFOAM SD 8260 is added at 0.10–0.30% w/w on total formulation mass, preferably split before and after bead milling to avoid excessive air incorporation during the high-energy grind. The self-dispersing silicone-polyether hybrid must remain compatible with the high ionic strength of the continuous phase, and formulation stability is assessed by visual observation after 24 h at 54°C according to CIPAC MT 46 and by suspension content measurement according to CIPAC MT 184. Persistent foam is measured after 1–10 min using CIPAC MT 47.2; in high-electrolyte SC formulations, addition of 0.20% w/w typically reduces the foam layer to a small broken collar, but published data for this specific hybrid in concentrated ammonium sulfate systems is limited. The finished product is packaged into 1 L HDPE bottles and 200 L drums, where low shear during filling can re-entrain air if the filling nozzle is not submerged below the liquid surface. In container closure systems with polypropylene caps and induction seals, the antifoam should not increase surface slip on the container neck because the dosage is low and the active content is well emulsified in the aqueous SC. For formulations with pH outside 5.5–8.5, compatibility must be retested; silicone-polyether hybrids can slowly hydrolyze in acid or alkaline SC systems, resulting in loss of defoaming efficiency and possible phase separation after 30 days at 40°C.
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SILFOAM SD 8260 is a solvent-free, 100 %-active silicone-polyether hybrid self-dispersing antifoam. The commercial grade belongs to the SILFOAM family of silicone-based defoamers and is supplied as a hazy yellowish liquid. The hybrid molecular architecture contains siloxane segments for low surface tension and foam rupture, alongside polyether segments that allow dispersion in aqueous media without an external emulsifier package. The supplier’s technical data lists a density near 1.00 g/cm³ at 20 °C and a Brookfield viscosity at 25 °C in the range 500–1500 mPa·s; the batch certificate of analysis controls exact lot values. The suffix SD denotes self-dispersing behavior, which removes the need for pre-emulsification equipment such as an inline rotor-stator homogenizer. The product is intended for waterborne coating, ink, and adhesive systems where conventional polydimethylsiloxane antifoams can create unacceptable surface defects. It is not designed for solventborne high-solids coatings or for silicone-free applications because the siloxane content remains present.
In a foam lamella, antifoam entry can be described by the entering coefficient E = γF + γDF − γD and the spreading coefficient S = γF − γDF − γD, where γF is the surface tension of the foaming liquid, γD is the surface tension of the antifoam droplet, and γDF is the interfacial tension between the droplet and the foaming liquid. A conventional PDMS droplet typically has a high spreading coefficient, which provides rapid lamella thinning but can generate craters if the droplet persists at the air–film interface. The polyether block in SILFOAM SD 8260 reduces the interfacial tension between the droplet and the aqueous phase and modifies the spreading pressure. Under moderate shear, the product forms microdroplets in the 5–50 µm range; these droplets remain sufficiently hydrophobic to enter foam films but are less likely to form large surface lenses. Foam knockdown and persistence are normally screened in waterborne formulations using the Red Devil shaker test according to ASTM D3601, with foam height recorded at 0 min, 5 min, and 10 min after shaking. A lower residual height at 10 min indicates better persistence of antifoam activity. High-shear processing above 20 m/s tip speed can reduce droplet size below the optimum range, resulting in an over-dispersed state that loses entry activity; this is a known operational boundary for self-dispersing hybrid antifoams.
In waterborne acrylic architectural coatings, addition rates are determined by ladder studies because foaming varies with free surfactant content, pigment volume concentration, and coalescent type. A starting point of 0.1–0.3 wt% based on total formulation is used in semigloss and matte latex systems; heavily pigmented or highly foaming formulations may require 0.3–0.5 wt%. Split addition is often evaluated, with 50% introduced in the grind and 50% in the letdown. If the full dose is added during pigment dispersion, free wetting agents can adsorb at the antifoam droplet surface and reduce defoaming persistence in the can. If the full dose is added at the end of letdown, localized concentration gradients may produce surface defects before the product is uniformly dispersed. Manufacturing trials should use a high-speed disperser equipped with a saw-tooth blade at 10–15 m/s tip speed; batch-to-batch differences in foam are frequently controlled more by surfactant concentration than by mixing time. Drawdowns over black glass panels are used to detect incompatibility as craters, pinholes, or haze, and specular gloss is measured by ASTM D523 at 20°, 60°, and 85° geometry.
The undiluted product has a pumpable viscosity profile. The supplier reports a Brookfield viscosity at 25 °C in the 500–1500 mPa·s range and density close to 1.00 g/cm³; rotational viscosity is typically measured according to ISO 3219, while density is determined by ISO 2811-1. The absence of a water carrier means the product does not exhibit freeze-thaw failure typical of emulsion antifoams. Cold storage below 0 °C can raise viscosity temporarily, and the product should be conditioned to 20–25 °C before dosing. Phase separation may develop after prolonged storage; gentle drum rolling or low-shear stirring is preferred over high-speed agitation because the self-dispersing character is shear-dependent. In water at 0.1%, the product forms a hazy dispersion rather than a clear solution; haze does not indicate incomplete mixing. Continuous dosing in paper coatings and ink processes should employ low-shear pumps such as progressive cavity or peristaltic pumps. Centrifugal pumps with high impeller shear can over-disperse the defoamer and reduce its antifoam efficiency in downstream application. This is a practical constraint in automated formulation lines where the additive is metered into a high-velocity recycle loop.
The difference from conventional antifoam classes is most apparent in waterborne overprint varnishes and high-gloss coatings. Conventional high-viscosity PDMS antifoams provide strong foam control but can form persistent oil lenses that reduce gloss or create fisheyes; mineral-oil defoamers are often compatible but may be less effective above 45 °C and can contribute to yellowing in white systems. SILFOAM SD 8260 is designed to occupy an intermediate compatibility zone. The polyether modification reduces the size of the dispersed antifoam droplets and allows the material to be incorporated without pre-emulsification, while the siloxane block maintains defoaming capacity. The comparison table below summarizes class-level distinctions; product-specific performance must be determined by drawdown and foam testing because formulation components can shift the balance.
| Parameter | SILFOAM SD 8260 hybrid | Conventional PDMS | Mineral-oil defoamer |
|---|---|---|---|
| Active content | 100% | 100% or emulsion | 100% or emulsion |
| Water dispersibility | Self-dispersing microdispersion | Requires emulsifier or may form separate oil phase | Limited; may require surfactant |
| Typical starting dosage | 0.1–0.5 wt% | 0.01–0.2 wt% | 0.2–1.0 wt% |
| Primary compatibility risk | Haze at high dosage | Craters and fisheyes | Gloss reduction and slow knock-down |
| Defect test standards | ASTM D523, ASTM D4062 | ASTM D523, visual crater assessment | ASTM D523, drawdown |
In two-component waterborne polyurethane systems and baked melamine formulations, addition timing affects not only foam but also surface quality and intercoat adhesion. The defoamer should be added after coalescent incorporation and pH stabilization. Extremes outside the typical formulation range of pH 7–9 are preferably avoided because the stability of the dispersed polymer itself becomes limiting; the antifoam is not the primary constraint. The product is not a reactive diluent and does not participate in isocyanate crosslinking, but its polyether block can behave as a surface-active component. Overdosing at 0.5 wt% or higher can create a low-surface-energy surface that impairs recoat adhesion. Crosshatch adhesion is evaluated by ISO 2409, and pull-off adhesion is measured by ASTM D4541. In practice, if the defoamer is added to a two-component mix after the isocyanate component, the short pot life may limit the time available for complete dispersion; therefore the product is usually incorporated into the resin component before mixing. Field data for this exact product in two-component systems are limited, so a formulation-specific adhesion and foam-control ladder study is required before full-scale use.
In flexographic and gravure printing inks, foam entrainment in the ink pan can produce print voids and uneven transfer. For water-based flexo inks, a starting addition of 0.05–0.2 wt% based on total ink is typically screened; the optimum is confirmed on a production press because anilox roll speed, doctor blade angle, and ink viscosity all influence foam generation. Defoamer persistence is assessed by circulating the ink through a laboratory print simulator or a small press for 30–60 min and measuring foam height and print skip frequency. The self-dispersing character of SILFOAM SD 8260 is particularly relevant here because non-dispersing silicone oils can accumulate on the impression roller and plate; with the hybrid, less free oil is available to form plate contamination. However, if the product is overdosed, dispersion haze can reduce color strength in high-transparency inks. No single addition level can be specified for all pigment types; published data for this specific configuration is limited.
Surface defects caused by antifoam incompatibility are evaluated after film formation, not only in the liquid state. In a high-gloss aqueous wood coating, a defoamer may pass the shaker test but still produce microfoam after drying or a loss of gloss from surface lens formation. Gloss is measured by ASTM D523 at 20°, 60°, and 85°. A drop of more than 5 gloss units at 60° relative to a control is often considered significant in quality control. Levelling and flow are evaluated by ASTM D4062 or by brush-out and drawdown comparisons. For SILFOAM SD 8260, the supplier’s technical data sheet identifies haze formation at high dosage as a compatibility boundary; formulation-specific testing is needed to find the highest acceptable addition level without gloss reduction. In emulsion paint production, visual crater assessment on a sealed black chart is insufficient to detect subtle haze; specular gloss measurement is required. If formulation solids are below 30% and the binder is a low-viscosity acrylic dispersion, the tolerance for over-dosage may be narrower than in a high-solids system. This is a relevant processing window because addition errors of 0.1 wt% can shift surface appearance in low-viscosity inks and clears.
Regulatory evaluation for food-contact applications is formulation-specific. The use of a silicone-polyether defoamer in a packaging coating does not automatically comply with all clearances. In the United States, a coating may be evaluated under 21 CFR 175.300 if the finished film meets extraction requirements; the defoamer is considered part of the coating formulation. In the European Union, overall migration testing under the EN 1186 series and specific migration limits under EN 13130 may be required depending on the final article and the intended contact conditions. REACH registration status and any harmonized classification should be confirmed from the supplier’s safety data sheet. Because the product is a polymer-containing preparation rather than a single monomeric substance, exact registration numbers vary by region. For industrial non-food applications, standard occupational hygiene data and the safety data sheet govern handling.
