Section
| HS Code | 882428 |
| Chemical Type | EO/PO block copolymer polyether |
| Appearance | colorless to slightly hazy liquid |
| Cloud Point Celsius | 24-28 |
| Viscosity At 25c Cps | 250-350 |
| Specific Gravity 25c | 1.00-1.02 |
| Ph 1 Percent Aqueous Solution | 6.0-7.5 |
| Water Solubility | slightly soluble in water, self-emulsifying |
| Surface Tension Dyne Cm | 35-40 |
| Hlb Value | 3-5 |
| Pour Point Celsius | -15 to -10 |
As an accredited L61 EO/PO Block Polyether Defoamer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 200 kg drums or 1,000 kg IBC totes, tightly sealed to prevent contamination and moisture ingress. |
| Container Loading (20′ FCL) | 20′ FCL loaded with L61 EO/PO polyether defoamer in drums/IBCs, secured, palletized, non-hazardous, ready for export. |
| Shipping | Ship as non-hazardous industrial chemical in sealed drums, IBCs, or ISO tanks. Protect from moisture, direct sunlight, and extreme temperatures during transit. Ensure containers are upright and well-ventilated. Avoid contact with strong oxidizers. Standard road, rail, or sea freight applies; no DG restrictions under normal conditions. |
| Storage | Store in tightly sealed containers in a cool, dry, well-ventilated area. Keep away from direct sunlight, heat sources, and incompatible oxidizing agents. Avoid moisture ingress and extreme temperature fluctuations. Ensure containers remain upright and undamaged. Use appropriate personal protective equipment when handling. Shelf life is typically stable under recommended storage conditions. |
| Shelf Life | Shelf life is typically 12 months when stored in sealed containers at room temperature, away from heat and moisture. |
L61 is a difunctional polyoxyethylene-polyoxypropylene block polyether with an ethylene oxide mass fraction of approximately 10%, an average molar mass near 2000 g/mol, and an HLB value between 1 and 3. Cloud point in 10% aqueous dilution is near 24°C, as measured by DIN 53917. These properties yield inverse water solubility and a film-spreading layer at gas-liquid interfaces in agitated fermenters. In submerged fermentation vessels of 50 m³ to 200 m³ working volume, the block polyether is introduced through a sterile dosing port after the sterilization cycle at 0.01% to 0.1% by broth volume. Aeration rates of 0.5 vvm to 1.5 vvm with dual Rushton impellers at tip speeds up to 6 m/s generate stable protein-polysaccharide foam that can reduce working volume by 20% to 30% without chemical foam suppression. L61 acts through droplet coalescence and film drainage rather than through foam generation, which limits oxygen transfer inhibition compared with high-dose hydrocarbon oil antifoams. Terminal products include citric acid, industrial alpha-amylase, and baking yeast cell mass.
Batch-to-batch variance in defoamer demand is observed when the feed contains high dissolved solids from corn steep liquor or molasses. In such systems, L61 is pre-emulsified in deionized water at a ratio of 1:10 before sterile filtration through a 0.2 µm membrane. The diluted stream is metered continuously at a rate proportional to carbon dioxide evolution or measured foam height. Foam height is monitored by conductivity probes in the headspace. If the addition rate exceeds 0.5 mL/kg broth per hour, downstream protein precipitation and ultrafiltration membrane flux decline by as much as 15% because unadsorbed block polyether accumulates in the retentate. Published data for this specific configuration is limited; therefore pilot-scale filterability trials are required for each strain. For enzyme and organic acid fermentations intended for food-contact applications, the block polyether falls within the permitted class of polyoxypropylene-polyoxyethylene condensates described in FDA 21 CFR 176.200 and FDA 21 CFR 176.210, provided residual levels meet extraction limits specified in FDA 21 CFR 176.170.
In high-PVC styrene-acrylic and vinyl-acetate-ethylene architectural coatings, macrofoam is entrapped during high-speed dispersion and during application by roller or airless spray. L61 is post-added at 0.1% to 0.5% by total wet formulation weight. Addition is preferably split: half during grind letdown at 25°C to 35°C and half in the final viscosity adjustment step. The block polyether has limited water miscibility. Direct addition into a vortex running above 800 rpm causes dispersed droplets larger than 50 µm, which later create surface craters. A predilution ratio of 1 part L61 to 9 parts water or coalescing solvent is therefore maintained, and the premix is metered into a tank under agitation of 300 rpm to 500 rpm for not less than 10 minutes.
Foam control performance is assessed by blade-stirrer foam tests following ASTM D3601-88(2017) using 200 mL paint at 25°C. At 0.3% loading, entrained air is typically reduced from 6% to 8% by volume to below 2% within 120 seconds. The risk boundary is at loadings above 0.5%, where the low-HLB block polyether migrates to the air-coating interface and produces haze in gloss films. For acrylic enamels with a target 60° gloss above 70 units, the loading should not exceed 0.2% unless rub-up compatibility data demonstrates no gloss reduction. The terminal products include interior and exterior wall paints, elastomeric roof coatings, and pigment dispersions. In coatings that must comply with FDA 21 CFR 176.200 for indirect food contact, the defoamer is limited to the residual levels allowed by the regulation.
At a machine speed of 1,200 m/min and headbox consistency of 0.4%, white water from a closed-loop paper machine carries dispersed air up to 0.8% by volume. Air entrainment reduces drainage on the forming fabric and creates pinholes in lightweight coated base papers. L61 is injected as a 1% to 5% aqueous dispersion into the wire pit or into the approach flow after the fan pump. The addition rate is 0.02 kg to 0.2 kg active block polyether per tonne of dry fiber. Continuous feed is preferred over slug dosing because foam generation follows broke ratio and temperature shifts between 40°C and 60°C. Foam level in the wire pit is monitored by ultrasonic sensors, and the dosing pump is throttled by a PID loop with a dead band of 5% of foam height.
Silicone-free operation is required for paper grades that receive extrusion coating or silicone release liners. Residual silicone defoamers can cause fish eyes and loss of adhesion in subsequent converting. L61 leaves no hydrophobic silicone film. However, at white water pH above 8.5 and temperature above 60°C, the block polyether partitions more strongly into the colloidal phase, and air release efficiency decreases by up to 20%. In such conditions, the product is applied closer to the headbox rather than the wire pit. Retention aid and cationic starch interactions should be tested by streaming current potential because the nonionic block polyether does not consume cationic charge. Terminal products include coated fine paper, recycled linerboard, and tissue. Porosity is tested according to TAPPI T 460 cm-02.
Semi-synthetic metalworking fluid concentrates are formulated at 5% to 10% in water for machining cast iron and aluminum. Foam in the machine sump is stabilized by tramp oil, finely divided metal fines, and hard water soaps. L61 is used as a silicone-free defoamer at 0.05% to 0.3% by volume in the diluted coolant. The block polyether is introduced into the concentrate during the cool-down phase below 40°C to prevent phase inversion. In a 500 L concentrate tank with a side-entry propeller at 500 rpm, addition of L61 over 15 minutes produces a clear-to-slightly-hazy concentrate that remains stable through six freeze-thaw cycles between -5°C and 25°C.
Foam tendency is measured by the ASTM D3601-88(2017) procedure adapted for water-diluted coolants. At 0.1% L61, foam volume in the 5% coolant at 25°C is typically below 50 mL after 5 minutes of aeration. The operational boundary is at tramp oil loads above 8%, where L61 competes with emulsified oil droplets for the air-water interface and antifoam efficiency drops sharply. In such conditions, the sump is skimmed or the dosing pump is adjusted to a maximum of 0.3%. Compatibility with boric acid esters and amine carboxylate corrosion inhibitors must be confirmed by storage tests because the block polyether does not ionically bind metal surfaces. Terminal products include aluminum milling coolants, cast iron grinding fluids, and drawing compounds. Cutting fluid mist and volatile organic compound load are not increased by the low-volatility polyether.
Vinyl acetate-ethylene and polyvinyl acetate dispersion adhesives entrain air during high-speed compounding, transfer, and gear pump metering. Air bubbles larger than 100 µm create spatter during nozzle application and reduce adhesive film coverage by 10% to 15% at the same wet film thickness. L61 is post-added at 0.1% to 0.3% by total adhesive weight. The block polyether is added under slow sweep mixing of 200 rpm to 300 rpm after the polymer dispersion has cooled below 35°C. High-shear dispersion above 1,000 rpm is avoided because it generates microfoam that is more difficult for the low-foam defoamer to coalesce.
Air content is measured gravimetrically against a reference density value from ISO 2811-1:2016. In a 100 kg tank, 0.2% L61 reduces air content from 3.5% to 0.8% within 30 minutes without destabilizing the dispersion. The critical risk is over-addition above 0.5%, which reduces shear adhesion on high-density polyethylene substrates because free block polyether migrates to the bond line. For water-resistant D3 and D4 wood adhesive formulations, adhesion is tested according to EN 204 and EN 205 after 7 days of conditioning at 23°C and 50% relative humidity. Terminal products include paper packaging adhesives, wood assembly adhesives, and cartridge sealants.
Jet dyeing of polyester and cotton at 135°C and 80°C respectively produces foam that can block circulation pumps and create unlevel dye uptake. L61 is applied at 0.1 g/L to 0.5 g/L in the dyebath before the fabric is loaded. The product is predispersed in cold water at a ratio of 1:20 and fed through the auxiliary chemical injection line. In a 500 kg jet machine with a liquor ratio of 1:5, foam height in the drain line is reduced within 10 minutes of circulation. The block polyether is low-foaming and does not generate silicone spots on finished fabric, which is critical for downstream printing and lamination.
The main processing conflict is electrolyte tolerance. In reactive dyeing of cotton with 80 g/L sodium sulfate or 50 g/L sodium chloride, the dilute L61 dispersion may separate if the temperature is below 25°C. The defoamer is therefore injected before salt addition or after the salt is fully dissolved at 40°C. At pH above 11 in pretreatment kier scouring, defoamer efficiency drops because the polyether remains water-solubilized. Terminal products include dyed knits, woven automotive fabrics, and antimicrobial finishing baths. Published data for industrial polyester jet dyeing with L61 is limited; laboratory dye-tube screening is required for each dyebath recipe.
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L61 EO/PO block polyether defoamer is a linear triblock copolymer with the nominal structure HO(CH₂CH₂O)x(CH(CH₃)CH₂O)y(CH₂CH₂O)xH and is classified under CAS 9003-11-6. Technical datasheets list an average molecular mass of approximately 2,000 g/mol, an ethylene oxide mass fraction of 10%, and a hydrophilic-lipophilic balance of 3.0. The product is supplied as a clear to slightly hazy, colorless to pale-yellow liquid with dynamic viscosity of 285 mPa·s at 25 °C, density of 1.01 g/cm³, and a pour point below −30 °C. A 1% aqueous cloud point near 24 °C places L61 at the hydrophobic end of the EO/PO block polyether series; above this temperature the copolymer separates from water as a fine, low-solubility liquid phase capable of entering and destabilizing foam films.
In aqueous surfactant-stabilized foam, the low ethylene oxide content limits hydration of the middle poly(propylene oxide) block, allowing the molecule to orient at the air-liquid interface with the poly(propylene oxide) segments directed away from the bulk water. The resulting interfacial monolayer has lower film elasticity than the adsorbed surfactant layer and promotes film drainage by reducing local surface-tension gradients. Because the active droplet must remain poorly water-soluble at process temperature, the cloud point is the primary specification variable controlling activity in hot aqueous systems.
Antifoam performance is not governed by concentration alone. In air-sparged screening tests based on ASTM E2407-04(2022), homogeneous cold-water addition of low-HLB EO/PO block polyethers can give incomplete knockdown because the polymer dissolves as a weak co-surfactant rather than existing as dispersed droplets. Heating the addition point above the 1% cloud point or pre-emulsifying the copolymer at 1,500–3,000 rpm in a rotor-stator disperser produces droplet sizes of 5–20 μm, which are within the range required for foam-film bridging in most aqueous process foams. In production-scale recirculating loops, injection downstream of a heat exchanger or into a venturi eductor provides both thermal inversion and hydrodynamic dispersion.
The threshold between foam control and foam stabilization is explained by film elasticity. In a thin liquid film stabilized by sodium dodecyl sulfate at 0.1 wt%, the Gibbs-Marangoni effect repairs local thinning; a dispersed low-HLB droplet entering the film creates a lens with lower interfacial tension and generates a capillary pressure gradient that accelerates drainage. The droplet must be larger than the film thickness, which in high-shear paper white water is often 10–50 μm. If the droplet is colloidally dissolved below the cloud point, no distinct lens forms and the foam film remains intact. This is why inline injection below the cloud point frequently requires 2–5 times the dose used above the cloud point.
The dose-response curve is commonly nonlinear. Published technical evaluations for low-EO polyether defoamers describe a defoaming plateau beginning near 50 mg/kg active in surfactant-loaded water; below 10 mg/kg, long drainage times persist because insufficient droplet number density exists in the foam lamellae. Above 200 mg/kg, excess copolymer can generate a secondary emulsified layer and increase foam stability in strongly agitated vessels. This threshold is formulation-specific; published data for L61 in high-protein fermentation broths is limited.
In fed-batch bacterial fermentation, L61 is typically introduced through a sterile 0.2 μm cartridge filter into the headspace or foam leg at an initial charge of 0.02–0.10 mL/L, followed by continuous addition of 5–20 mL/h in a 10,000 L stirred vessel. Operators monitor foam height rather than defoamer concentration because soluble protein load, agitation power input, and broth viscosity shift the demand. The operational boundary is oxygen transfer: excessive defoamer can collapse the foam blanket and reduce volumetric mass transfer coefficient below the minimum required for aerobic metabolism. Published production data for this specific configuration is limited; therefore, dose frequency is typically established by on-site foam-height trending and dissolved oxygen response rather than by a single fixed rate.
Batch acceptance commonly verifies cloud point, water content, viscosity, color, and hydroxyl value. A representative specification matrix is given below; the exact limits may vary by supplier and end-use regulatory listing.
| Parameter | Typical specification | Test method |
|---|---|---|
| Appearance | Clear to slightly hazy liquid, free of visible gel | Visual inspection against light background |
| Color | ≤50 APHA / Pt-Co | ASTM D1209 |
| Average molecular mass | 1,900–2,100 g/mol | GPC with poly(ethylene glycol) calibration |
| Ethylene oxide content | 9.0–11.0 wt% | NMR or supplier method |
| Hydroxyl value | 50–60 mg KOH/g | ASTM D4274 |
| pH, 1% in water | 5.0–7.5 | ASTM E70 |
| Water content | ≤0.5 wt% | ASTM E203 |
| Dynamic viscosity at 25 °C | 250–320 mPa·s | ISO 2555 |
| Density at 25 °C | 1.00–1.02 g/cm³ | ASTM D4052 |
| Cloud point, 1% aqueous | 22–26 °C | ISO 1065 |
A cloud point below 22 °C can reduce ease of dilution in cool water skids, while a cloud point above 26 °C may require higher addition rates in fermenters operating at 30–37 °C. For recirculating paper machine white water at 40–50 °C, a low cloud point is advantageous because the defoamer is already phase-separated at the point of injection. Batches with water content above 0.5 wt% may exhibit haze on storage and require nitrogen blanketing to prevent hygroscopic pickup.
Polydimethylsiloxane-based antifoams, particularly those compounded with hydrophobic silica, depress equilibrium surface tension below 25 mN/m and can be effective at doses of 1–5 mg/L. However, their low water solubility and high adhesion to polymer surfaces create persistent deposits that reduce membrane flux and can generate coating defects. L61 belongs to a silicone-free class; its activity derives from a temperature-triggered phase separation rather than from dispersed solid particles, so filtration losses through 0.45 μm membranes are lower and clean-in-place with warm water above the cloud point is more effective.
Compared with mineral oil defoamers, which often contain paraffinic carriers and hydrophobic wax/silica solids, L61 contains no hydrocarbon carrier oil and does not leave a mineral-oil film on calender rolls or heat-exchanger surfaces. The trade-off is dose: mineral oil and silicone products can achieve rapid knockdown at lower active concentrations in short-contact applications, whereas L61 may require 2–10 times higher mass addition in cold aqueous systems because its interfacial activity depends on phase separation. In high-shear paper coating color, L61 is metered at 0.1–0.3 wt% on total wet formulation; silicone defoamers at similar use rates can produce visible fish-eyes in the dried coating.
Relative to higher-EO block polyethers such as L62 or L64, L61 is more hydrophobic and more effective at destabilizing macrofoam in waterborne systems. Higher-EO grades carry greater water solubility and can function as foam stabilizers or wetting agents rather than defoamers in some formulations. In starch-based paper coatings, substitution of L61 for a 20% EO block polyether typically lowers foam drainage time but may also reduce sheet gloss if the defoamer is not fully dispersed during pigment grind; therefore, the addition point is moved upstream into the high-shear disperser rather than to the letdown tank.
In waterborne polyurethane dispersions and acrylic emulsion paints, L61 is used where recoatability and film clarity are more critical than absolute defoaming speed. It is typically added during pigment grind at 0.1–0.3 wt% on total formulation weight. The high-shear grind stage breaks the defoamer into droplets of 10–30 μm, which migrate to the air-liquid interface during drying and coalesce microfoam. Addition at letdown below 500 rpm often leaves large droplets that produce surface craters in the dried film. Because L61 does not contain solid silica, it tends to have lower low-angle haze contribution than many silicone-silica concentrates.
Storage at ambient temperature in closed stainless steel or high-density polyethylene totes is standard; carbon steel is acceptable only with an epoxy phenolic lining. Because L61 is hygroscopic and its cloud point shifts downward in the presence of electrolytes, mixed waste streams containing high concentrations of sodium sulfate or magnesium chloride may require point-of-use warming. Avoid contact with strong oxidizing agents such as peroxides or hypochlorite, which can cleave the polyether backbone and generate low-molecular-weight carbonyl compounds.
