Section
| HS Code | 430530 |
| Product Name | XP-066N Polyether-Modified Silicone Defoamer |
| Alternative To | BYK-066N |
| Chemical Type | Polyether-modified silicone |
| Active Content | 100% |
| Appearance | Clear to slightly hazy liquid |
| Viscosity At 25c | 10-30 mPa·s |
| Density At 20c | 1.00-1.03 g/cm³ |
| Flash Point | Greater than 100°C |
| Water Solubility | Soluble in water and most organic solvents |
| Recommended Dosage | 0.2-1.0% based on total formulation |
| Effective Temperature Range | Up to 150°C |
| Compatibility | Compatible with waterborne, solvent-borne, and high-solids coating systems |
| Foam Control Mechanism | Rapid foam collapse and sustained defoaming activity |
| Impact On Appearance | Minimal risk of cratering, fish eyes, or orange peel |
| Viscosity Stability | Stable over a wide pH range from 3 to 10 |
| Voc Content | Zero or negligible VOC |
| Shelf Life | 12 months from date of manufacture in unopened original container |
As an accredited XP-066N Polyether-Modified Silicone Defoamer for Waterborne/Solvent Coatings–BYK-066N Alternative factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | XP-066N polyether-modified silicone defoamer, an alternative to BYK-066N, packaged in 25 kg plastic drums for waterborne/solvent coatings. |
| Container Loading (20′ FCL) | 20′ FCL: 20-foot container loading of XP-066N defoamer, palletized drums/IBCs, safe, secure, compliant transport. |
| Shipping | XP-066N polyether-modified silicone defoamer ships as a non-hazardous industrial liquid. No dangerous goods classification applies. Use standard ground or LTL freight in sealed drums, pails, or totes. Protect containers from freezing, excessive heat, and moisture during transit. Ensure proper labeling and secure palletization. |
| Storage | Store XP-066N in its original, tightly closed container in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Avoid freezing and extreme temperature fluctuations. Keep container sealed when not in use to prevent contamination or evaporation. Use within manufacturer-recommended shelf life, typically 12 months from manufacture date. |
| Shelf Life | Recommended shelf life is 24 months from manufacture when stored in original containers below 40°C, away from direct sunlight. |
In high-PVC interior matte and eggshell formulations where BYK-066N is specified, XP-066N is incorporated at 0.15–0.30 wt% of the total formulation. The millbase contains 8–12% titanium dioxide, 10–15% calcined clay, and 5–8% talc. Half of the defoamer dose is introduced into the millbase after pigment wetting at 1.0–1.2 m/s tip speed. The remaining half is added to the letdown before the associative thickener to limit competition for micelle formation. A Cowles high-shear disperser is operated at 4.0–5.5 m/s during pigment dispersion and reduced to 0.8–1.2 m/s for thickening. Air release is monitored by density increase under ISO 2811-1:2016; a rise of 0.02–0.05 g/cm³ after 24 h indicates removal of entrapped microfoam. The finished batch is filtered through a 100–150 µm bag. Pinholes are assessed on 200 µm wet drawdowns. Above 0.35 wt%, cratering and intercoat adhesion loss can appear after 7 days at 40°C. The end product is a roller-applied interior eggshell or matte wall paint with wet scrub resistance evaluated under ASTM D2486-19.
Curtain coating lines for flat-line furniture parts expose the wet film to the atmosphere for less than 8 s before infrared pre-drying. Microfoam that survives the curtain must therefore be released before gelation, or pinholes remain in the sanding sealer. The defoamer is added at 0.05–0.20 wt% of total formulation after the letdown, under a blade stirrer at 300–500 min⁻¹. A maturation period of 12–24 h at 20–25°C is required before the batch enters the coating head. Curtain speeds of 60–100 m/min and wet film thicknesses of 150–250 µm are typical for MDF and solid wood panels. The end product is a 35–40% solids waterborne sanding sealer for interior furniture. Haze is controlled under ISO 13803:2014, and 60° gloss is measured by ASTM D523-14. Above 0.25 wt%, haze in the clear film increases and the system is not recommended for high-gloss topcoats.
Because waterborne 2K epoxy zinc phosphate primers are sprayed through plural-component airless equipment, air entrainment can occur in both the millbase and the mixed material. XP-066N is incorporated into Part A at 0.2–0.5 wt% after the zinc phosphate and extender pigments have been dispersed. The addition is not made to the amine hardener. A high-shear Cowles disperser is used at 3.5–5.0 m/s for pigment dispersion, followed by a 10 min low-speed sweep at 0.8–1.0 m/s to release millbase foam. Mixed material is applied with a plural-component airless spray unit at 30:1 ratio, fluid pressure 180–230 bar, and tip orifice 0.017–0.021 in. Pot life is 2–4 h. Pinholes in the 60–100 µm dry film are assessed before overcoating. Salt spray resistance is tested per ISO 9227:2017, and pull-off adhesion per ISO 4624:2016. Above 0.5 wt%, wetting defects on blast-cleaned steel can appear under high humidity; pre-drying is required at relative humidity above 60%. The end product is a zinc phosphate shop primer for interior steel structures.
Waterborne OEM basecoat circulation loops operate at reduced surface tension, which stabilizes sub-50 µm air inclusions. XP-066N is introduced at 0.1–0.3 wt% of the liquid coating after the binder dispersion and before the final rheology modifier. The target is to reduce microfoam without reducing the shear-thinning profile required for bell atomization. Robotic high-rotation bell atomizers are used at 30,000–50,000 min⁻¹, with a 15–25 µm dry film applied over electrocoat. After 3 min flash-off at 60°C, the basecoat is overcoated with a solventborne clearcoat. Pinholes and craters are counted on full panels after clearcoat bake at 140°C for 20 min. Cross-cut adhesion is tested per ASTM D3359-17, and distinctness of image is checked after clearcoat application. A dosage ceiling of 0.35 wt% is observed; above this level, dewetting on electrocoat and plastic components can occur. The end product is a waterborne OEM basecoat for automotive body panels.
On reverse roll coating lines for waterborne polyester-melamine coil primers, air is introduced through the rolling bank and recirculating pan. XP-066N is added at 0.1–0.3 wt% of total formulation after the melamine-formaldehyde crosslinker and acid catalyst have been incorporated. Line speeds of 80–180 m/min and dry film thicknesses of 5–10 µm require complete air release before the sheet enters the first oven zone. Peak metal temperature is 210–232°C for 20–40 s. Residual microfoam then appears as pinholes or craters in the cured primer, particularly over hot-dip galvanized substrate. The end product is a coil primer for building cladding and appliance panels. Cure and adhesion are evaluated under EN 13523-6:2014 for adhesion after drawing and EN 13523-8:2017 for resistance to salt spray. Above 0.3 wt%, wetting on zinc-coated steel can become irregular at line speeds above 120 m/min.
| Coating system | Addition range | Incorporation point | Observed ceiling |
|---|---|---|---|
| High-PVC architectural latex | 0.15–0.30 wt% | Split grind/letdown | 0.35 wt% |
| Waterborne wood sanding sealer | 0.05–0.20 wt% | Post-letdown maturation | 0.25 wt% |
| 2K epoxy zinc phosphate primer | 0.2–0.5 wt% | Part A only | 0.5 wt% |
| Waterborne OEM basecoat | 0.1–0.3 wt% | After binder, before rheology modifier | 0.35 wt% |
| Waterborne coil primer | 0.1–0.3 wt% | After melamine and catalyst | 0.3 wt% |
| Solventborne alkyd topcoat | 0.05–0.15 wt% | Reduction stage after driers | 0.20 wt% |
| Waterborne flexo OPV | 0.1–0.3 wt% | After neutralization, before viscosity adjustment | 0.3 wt% |
In solventborne long-oil alkyd formulations, the defoamer must remain compatible after white spirit reduction and drier addition. XP-066N is incorporated at 0.05–0.15 wt% during the reduction stage, after cobalt and zirconium driers have been pre-diluted into the thinning solvent. The batch is mixed with a turbine stirrer at 500–800 min⁻¹ for 15 min. Pneumatic spray application at 2.0–2.5 bar with a 1.2–1.4 mm nozzle produces a 30–40 µm wet film. The end product is a clear or lightly pigmented alkyd topcoat for wood and metal trim. Pendulum hardness is tested under ISO 1522:2006, and 60° gloss under ASTM D523-14. A dosage above 0.20 wt% can produce persistent craters in high-gloss clears, particularly at 25°C and relative humidity below 40%. The product is not evaluated for acid-catalyzed urea-formaldehyde wood varnishes, where silicone additives may interfere with cure.
Waterborne flexographic overprint varnishes are recirculated through chambered doctor blade systems at printing speeds of 150–300 m/min. The defoamer is dosed at 0.1–0.3 wt% after the acrylic emulsion has been neutralized to pH 8.0–8.8 and before final viscosity adjustment. Addition is made under slow stirring at 200–400 min⁻¹ to avoid re-entraining air. The finished OPV is applied through an anilox roller at 200–400 lpi and 4–8 g/m² wet film weight over printed paperboard. Foam in the return tray must be released within a single circulation cycle of roughly 20–40 s. Gloss is measured at 60° per ASTM D523-14, and blocking resistance is checked at 40°C and 60% relative humidity. Above 0.3 wt%, print mottle and ink transfer defects can occur on low-absorbency folding carton stock. The end product is a waterborne OPV for folding carton packaging, applied inline on a central impression press.
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XP-066N is a polyether-modified polydimethylsiloxane defoamer positioned as a direct alternative to BYK-066N for solventborne and waterborne coating systems where a nonionic, solvent-free antifoam is required. The product is supplied as a clear to slightly turbid liquid with a target non-volatile content of ≥98%; the silicone backbone is grafted with polyether chains to moderate surface activity and reduce the cratering tendency associated with unmodified dimethylpolysiloxane. The recommended addition range is 0.1–1.0% based on total formulation weight, with the lower portion of the range used for microfoam suppression in high-gloss clears and the upper portion reserved for persistent macrofoam generated by high-surfactant waterborne binders. In comparison with the reference material, BYK-066N, the XP-066N specification is indexed against the reference values of 1.03 g/cm³ density, 1.457 refractive index at 25 °C, and 100% active matter.
The defoaming mechanism is primarily amphiphilic. The dimethylsiloxane portion migrates toward the air–liquid interface and lowers local surface elasticity, while the polyether segment provides limited compatibility with polar binder solutions. That structural balance reduces the risk of visible incompatibility droplets in waterborne acrylics but still permits rapid bubble release. Unlike silica-filled polydimethylsiloxane defoamers, XP-066N does not depend on dispersed hydrophobic solids to break foam lamellae; therefore, high-speed dispersion does not generate the heavy, filterable particles that can block 50 μm bag filters or create crater nuclei in thin films. This distinction is important in pressure-pot spray applications where the coating is filtered at 25–50 μm immediately before atomization.
The product is not a carrier-oil defoamer. Mineral oil grades introduce a separate oily phase that can remain in the dried film and reduce intercoat adhesion if the recoat interval is short. XP-066N does not add a hydrocarbon carrier; its active material participates in interfacial deaeration and remains dispersed in the binder. In forced-cure coil lines operating at 80–120 m/min and bath temperatures of 35–40 °C, petroleum-based defoamers can lose deaeration capacity as the coating bath ages, whereas polyether-modified silicone chemistry is generally more temperature-stable. Published data for this specific configuration is limited.
Each batch of XP-066N is controlled against a specification envelope that includes non-volatile content, density, refractive index, dynamic viscosity, and flash point. The methods align with ISO procedures to permit comparison with imported and domestically produced silicone defoamers. The table gives the target acceptance window and the reference value published for BYK-066N.
| Parameter | Test Method | XP-066N Acceptance Window | BYK-066N Reference Value |
|---|---|---|---|
| Non-volatile content | ISO 3251 | 98–100% | 100% |
| Density, 25 °C | ISO 2811-1 | 1.02–1.06 g/cm³ | 1.03 g/cm³ |
| Refractive index, 25 °C | ISO 280 | 1.450–1.462 | 1.457 |
| Dynamic viscosity, 25 °C | ISO 3219 | 300–800 mPa·s | 400–800 mPa·s |
| Flash point | ISO 3679 | >100 °C | >100 °C |
The acceptance window is broader than the reference in density and refractive index because supplier-to-supplier polyether chain length distribution can shift these values without changing defoaming efficiency. Density is determined by the pycnometer method of ISO 2811-1 at 25 °C; dynamic viscosity is measured with a rotational viscometer according to ISO 3219 at 25 °C and a shear rate of 10 s-1. A certificate of analysis that reports only non-volatile content is insufficient for a BYK-066N alternative because silicone defoamer activity is not proportional to solids alone. Foam-kill testing in the intended basecoat, clearcoat, or stain is required.
For mill-base incorporation, XP-066N is typically charged before pigment addition at 0.2–0.5% of total mill-base weight. In a production dissolver equipped with a cowles blade and a tip speed of 5–8 m/s, the defoamer distributes within 10–15 min; the polyether-modified silicone does not rely on shear-sensitive hydrophobic silica, so defoaming activity survives the full dispersion cycle. The product should be added slowly into the vortex to avoid localized high concentration that can form non-diffusing droplets. Processing temperature should remain below 60 °C; above this threshold, polyether chains may lose compatibility in highly aromatic solventborne systems and cause visible surface defects after application.
Post-addition during letdown is permitted but requires controlled mixing. The recommended minimum shear is 1–2 m/s tip speed with a pitched-blade turbine or dissolver. In low-viscosity waterborne stains below 500 mPa·s at 25 °C, post-addition without sufficient agitation can produce discrete oil-like droplets that appear as fisheyes after brushing. Addition after the final associative thickener stage requires 10–15 min of mixing; the vortex should be maintained but not drawn to the shaft, which would entrain additional air and reduce defoamer efficiency.
Equipment experience shows that loss-of-vortex addition is a common processing bottleneck. When XP-066N is poured into a stationary batch, it floats on the surface because its density is lower than waterborne binders; subsequent low-speed stirring at 0.5 m/s is often insufficient to pull the material into the bulk. This can produce batch-to-batch variation in foam control even when the same mass of defoamer is dosed. Automated dosing systems should be calibrated for a density of 1.02–1.06 g/cm³ and a viscosity of 300–800 mPa·s; mass-flow meters with a lower viscosity assumption will under-dose or cavitate if the pump is undersized.
Post-addition may be selected when a single dosing line serves both waterborne and solventborne products, or when the mill base is common to several finished goods with different foaming tendencies. Under these conditions, the dosage may need to be increased by 10–20% relative to a mill-base addition to achieve the same bubble release, because the defoamer must first distribute through a higher-viscosity binder phase rather than entering the grind at low viscosity. In a two-component polyurethane clearcoat applied at 120 μm wet film and cured for 30 min at 60 °C, an addition of 0.4% XP-066N by total weight can preserve gloss measured at 20° and 60° according to ASTM D523, but this outcome is formulation-specific and should be verified with the target hardener.
Post-added XP-066N must not be diluted with aromatic hydrocarbons before addition to a waterborne basecoat if the solvent concentration would disrupt the dispersion. The product is compatible with butyl acetate, xylene, and propylene glycol methyl ether acetate at typical addition levels, but pre-dilution can shift the solubility parameter of the mixture and reduce defoaming. Avoid pre-blending with amine catalysts or strong alkaline additives; basic conditions can promote silanol condensation and generate gel-like particles that settle in the container or block spray tips.
In waterborne acrylic trim enamels with a pigment volume concentration of 15–25%, associative polyurethane thickeners tend to stabilize fine foam that persists into the dried film as pinholes. XP-066N is evaluated at 0.3–0.6% on total formulation weight, added after the pigment slurry and before final viscosity adjustment. Drawdowns on sealed Leneta charts at 200 μm wet film, dried at 23 °C and 50% RH for 24 h, are examined under collimated light for macrofoam and under a 50× microscope for microfoam. Because the defoamer is nonionic, it generally exhibits lower interaction with anionic acrylic binders than cationic silicone emulsions; nevertheless, the addition should be optimized incrementally because excess can lower the static surface tension and create edge crawling on contaminated substrates.
In waterborne polyurethane dispersions with a minimum film-forming temperature below 0 °C and a particle size of 60–100 nm, foam is stabilized by emulsifiers and can persist through drying. XP-066N at 0.2–0.5% is added during the letdown before coalescent addition. Because the polyether-modified silicone has a refractive index close to that of many binders, clear films do not develop visible haze when the dosage is kept below 0.5%. The product should be evaluated for early water resistance according to ASTM D870 if the coating is used in exterior clear varnishes; silicone surface activity can reduce water resistance if the dosage is excessive.
For solventborne acrylic-melamine clearcoats applied by air-atomized spraying, XP-066N is used in the range of 0.1–0.3% to avoid haze. In these systems, foam is less persistent than in waterborne formulations, but air entrainment during recirculation through a mixing block can generate microfoam that appears as pinholes after flash-off. The product is added to the mill base at 0.2% before pigment dispersion or to the letdown at 0.2% with 15 min of recirculation. Gloss is measured at 60° in accordance with ASTM D523; the target is to remain within the repeatability limit of ±1.5 units relative to the defoamer-free control.
In forced-dry alkyd enamels cured at 80 °C for 20 min, rapid solvent evaporation can enlarge entrained bubbles before film solidification. XP-066N at 0.2% can be incorporated after the final resin addition; however, high-solid alkyds above 65% non-volatile content may require a higher dosage or a longer mixing time because the defoamer’s solubility balance shifts in the resin matrix. Published data for high-solid alkyds is limited; users should generate a ladder from 0.1% to 0.6% to determine the defect threshold.
Defoamer selection is commonly made among mineral oil, silica-filled polydimethylsiloxane, polyacrylate, and polyether-modified silicone. The matrix below distinguishes XP-066N from the other classes under the industrial conditions that most influence film appearance and production stability.
| Defoamer Class | Mechanism | Typical Dosage | Appearance Risk | Operational Limitation |
|---|---|---|---|---|
| Mineral oil | Insoluble oil droplet spreading at air-liquid interface | 0.3–1.5% | Moderate to high haze risk in high-gloss clears | Efficiency loss above 40 °C; oil exudation on storage |
| Silica-filled PDMS | Hydrophobic solid particle rupture of foam lamellae | 0.1–0.8% | High cratering and fisheye risk if over-dispersed | Filter plugging and visible particles in clears |
| Polyacrylate | Controlled incompatibility through polymeric surfactant functionality | 0.2–1.0% | Low haze; may lower block resistance | Less effective in high-surfactant sanding sealers |
| Polyether-modified silicone (XP-066N) | Polyether-silicone amphiphilic deaeration and foam destabilization | 0.1–1.0% | Low in clear systems at recommended dosage | Potential surface defects above 1.2%; limited published data in high-solids alkyds |
Relative to BYK-066N, XP-066N adopts the same polyether-modified silicone mechanism rather than a silica-containing silicone. The practical difference is supply-chain control: the batch viscosity window is retained, and the certificate of analysis should be reviewed for automated lines where dosing pumps are calibrated for a density close to 1.0 g/cm³ and viscosity of 400–800 mPa·s. Differences in polyether chain length distribution may shift compatibility very slightly in high-polarity waterborne systems, but this is not observed as a change in active content when measured by ISO 3251.
Compared with polyacrylate defoamers, XP-066N provides a lower tendency to depress block resistance in waterborne trim paints, but it may be less effective in highly pigmented pastes where the mechanical action of the defoamer is less important than the deaerating action of a less compatible polymeric surfactant. The selection should be made by ladder testing in the actual formulation rather than by generic class claims.
XP-066N is not recommended for cationic electrodeposition coatings because a nonionic silicone at the deposition interface can interfere with uniform film formation. It should not be used in tin-catalyzed condensation RTV systems where silicone addition may alter cure kinetics. For food-contact packaging applications, the raw defoamer is not itself a food-contact material; compliance must be assessed on the final cured film under 21 CFR 175.300, EU Regulation 10/2011, or equivalent national standards, including any specific migration limits.
Storage in partially filled containers under RH > 60% can increase moisture uptake and accelerate silanol formation. The use of dry nitrogen blanketing is recommended when drums are accessed frequently. In sealed original containers stored at 5–30 °C, shelf life is 24 months from the date of manufacture. Beyond that period, the product should be re-qualified by density, viscosity, and foam-kill testing before use.
Operational boundaries include a maximum recommended addition of 1.2% for unpigmented clearcoats; above this level, the risk of surface defects increases rapidly even if foam control improves. The product should not be combined with strong oxidizing agents or concentrated acidic catalysts. If persistent foam remains at 1.0%, the formulation’s air entrainment source should be investigated rather than increasing the silicone dosage indefinitely.
