Section
| HS Code | 241886 |
| Chemical Type | EO/PO block polyether |
| Appearance | Colorless to light yellow transparent liquid |
| Active Content | 99.5% |
| Viscosity At 25 C | 200-400 mPa·s |
| Cloud Point 1 Aqueous Solution | 25-30°C |
| Ph 1 Aqueous Solution | 6.0-7.0 |
| Specific Gravity At 25 C | 1.01-1.03 |
| Water Solubility | Dispersible in water |
| Pour Point | -30°C |
| Surface Tension At 25 C 0 1 Solution | 35-40 mN/m |
As an accredited L31 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, 1000 kg IBC containers, or 25 kg pails, with sealed lids for safe storage and transport. |
| Container Loading (20′ FCL) | 20′ FCL loading of L31 EO/PO Block Polyether Defoamer: secure drums/IBCs on pallets, protect from moisture, ensure safe stowage. |
| Shipping | L31 EO/PO Block Polyether Defoamer ships in sealed drums or IBC totes, protected from moisture and direct sunlight. It is typically non-hazardous cargo, but avoid extreme temperatures. Secure upright during transport, keep containers tightly closed, and store in a cool, dry area to prevent contamination. |
| Storage | Store L31 EO/PO Block Polyether Defoamer in a clean, tightly sealed container away from moisture, direct sunlight, and extreme heat. Keep in a cool, dry, well-ventilated area between 5–35°C. Avoid contact with strong oxidizers or acids. Prevent freezing. Use proper labeling and maintain good housekeeping to avoid spills. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored sealed in original containers under cool, dry conditions. |
In aerobic submerged fermentation for citric acid, lactic acid, and enzyme production, 0.05–0.2 g/L of L31 EO/PO block polyether defoamer is metered into the foam layer rather than the bulk liquid during the exponential growth phase. The product’s EO/PO block structure, with a 10% aqueous solution cloud point in the 37–42 °C range, destabilizes protein–polysaccharide foam lamellae formed by extracellular microbial surfactants. In a 150 m³ 316L stainless steel fermenter with two Rushton turbines operating at 1.5–2.5 W/kg ungassed power input and 0.6–1.0 vvm air flow, foam height is held below 0.3 m when a conductance foam probe activates a peristaltic pump. The volumetric oxygen transfer coefficient remains within 90–95% of the untreated control as monitored by the dynamic gassing-out method. Industry compliance: for food-ingredient fermentations, the defoamer is permitted as a processing aid under 21 CFR 173.340; for industrial enzymes and bio-based chemicals, EU REACH registration and ISO 22000 prerequisite programs apply. Formulation addition ratio: 0.05–0.2 g/L continuous feed based on working volume, with total batch additions not exceeding 0.3% v/v. Downstream production process: after media sterilization at 121 °C for 30 min, the defoamer is either prediluted 1:10 in sterile water and introduced through a 0.22 μm PVDF filter or aseptically injected through a stainless steel nozzle at 0.5–1.0 bar. Terminal finished product types: citric acid monohydrate, sodium lactate, protease and amylase preparations, amino acids, baker’s yeast, and probiotic biomass. Operational boundary: addition above 0.5% v/v in protein-rich broths may reduce oxygen transfer by more than 15%; published data for this specific configuration is limited.
Addition of 0.02–0.5 kg per tonne of oven-dry pulp into low-consistency stock at 0.8–1.2% consistency after the pressure screen reduces entrained air from 1.8–2.5% by volume to below 0.5% in closed whitewater loops. Foam generated by black liquor soap and fatty acid carryover in countercurrent washing filtrate collapses within 10–20 s in ASTM E2407-04 foam penetration tests, while first-pass retention measured on a dynamic drainage analyzer remains statistically unchanged up to 0.3 kg/t when used with a cationic polyacrylamide retention aid at 0.03–0.05% on dry fiber. Industry compliance: 21 CFR 176.210 permits polyoxyethylene-polyoxypropylene block polymers as defoaming agents in the manufacture of paper and paperboard intended for food contact; EU REACH registration and BfR Recommendation XXXVI apply to exported food-contact grades. Formulation addition ratio: 0.02–0.5 kg/t oven-dry pulp, normally introduced as a 1:5 to 1:10 dilution in process water. Downstream production process: the diluted defoamer is injected into the whitewater silo or stuff box ahead of the fan pump, not directly into the headbox, to avoid localized surface tension depression that causes wire flooding. Terminal finished product types: bleached folding boxboard, greaseproof paper, tissue and napkin base sheets, and corrugating medium. Operational boundary: in mills running pH 7.5–8.5 with AKD sizing, total defoamer addition above 0.5 kg/t may reduce Hercules sizing test values by 10–15% because of interference with sizing emulsion retention.
Activated sludge plants treating high-solids food processing effluent are dosed with 1–5 ppm L31 based on aeration basin liquid volume via a diaphragm pump located at the foam accumulation zone near the weir. The product collapses filamentous foam generated by Microthrix parvicella or Nocardioforms within 30–60 s in jar tests following ASTM E2407-04, while mixed liquor suspended solids remain at 3,500–5,000 mg/L. Industry compliance: EU REACH registration applies to the industrial wastewater service; the discharge route is controlled under local consent-to-discharge limits for residual nonionic surfactants, and no U.S. FDA clearance is required for this non-food-contact application. Formulation addition ratio: 1–5 ppm of aeration basin volume, adjusted to foam coverage and microscope filament counts. Downstream production process: the defoamer is injected above coarse-bubble diffuser grids at the point of maximum surface turbulence to distribute it across the foam without passing through the return activated sludge line. Terminal finished product types: clarified effluent for municipal discharge or tertiary membrane filtration, thickened waste activated sludge, and biogas from downstream anaerobic digestion. Operational boundary: in membrane bioreactors, doses above 10 ppm can increase transmembrane pressure by 20–30% within 48 h due to membrane surface wetting; a flat-sheet cell test is required before continuous use.
In high-shear overflow jet dyeing of polyester and polyester/spandex knits, 0.05–0.3 g/L of L31 is introduced into the dyebath before high-energy disperse dye addition. The defoamer suppresses entrained air in the fabric rope at 130 °C and 1.5–2.0 bar nozzle pressure, preventing float and rope marks in closed-loop machines. Industry compliance: textile auxiliaries must meet ZDHC MRSL v3.1 Level 1 for non-intentional addition of restricted substances; finished articles certified to OEKO-TEX Standard 100 Annex 4 must meet surfactant residue limits. Formulation addition ratio: 0.05–0.3 g/L of bath volume, added as a prediluted 1:5 aqueous dispersion. Downstream production process: the prediluted defoamer is added at 40 °C before dye dissolution in a bath ratio of 1:5–1:10 and circulation rate of 20–40 L/kg·min. Terminal finished product types: dyed polyester jersey, sports apparel, automotive seat fabric, and warp-knit automotive headliner. Operational boundary: avoid combining with silicone-based antifoams in the same bath; competitive adsorption onto disperse dye dispersants can shift dye uptake by 2–5% in pale shades, requiring dye recipe adjustment.
Semi-synthetic metalworking fluid concentrates containing 0.05–0.5 wt% L31 exhibit reduced foaming during high-pressure coolant delivery, as measured by ASTM D892-23 Sequence I at 24 °C and Sequence III at 93.5 °C. The block polyether functions as a low-foam nonionic dispersant for emulsifiable oil droplets with a mean droplet diameter of 20–80 μm in 5–8% tap water dilutions, without destabilizing the emulsion separation index beyond 2% after 24 h. Industry compliance: the fluid matrix is classified under ISO 6743-7 for liquid metalworking fluids; EU REACH registration applies to the defoamer as an industrial lubricant component. Formulation addition ratio: 0.05–0.5 wt% of the concentrate. Downstream production process: L31 is charged into the concentrate blend at 40–50 °C after rust inhibitors and before biocide addition; high-shear mixing at 1,500–2,000 rpm for 15–20 min disperses the product. Terminal finished product types: water-miscible cutting fluids used in CNC milling, tapping, and grinding of cast iron, steel, and aluminum alloys. Operational boundary: in hard water above 400 ppm CaCO₃, the diluted emulsion may reach its cloud point at 35–40 °C, producing a visible haze that does not affect foam control but may be mistaken for emulsion failure.
During wet milling of aqueous suspension concentrates, 0.05–0.3% w/w L31 is added to the premix before the bead mill to suppress air entrainment and prevent foam accumulation in the mill chamber. Foam control is assessed according to CIPAC MT 47.3 persistent foam method; foam volume after 1 min remains below 10 mL in a 50 g/L surfactant-containing SC formulation. Industry compliance: formulations are developed under the FAO/WHO Manual on Development and Use of FAO and WHO Specifications for Pesticides; EU REACH registration and local pesticide registration data requirements apply. Formulation addition ratio: 0.05–0.3% w/w in the final suspension concentrate. Downstream production process: the defoamer is incorporated into the aqueous premix at 20–30 °C before adding active ingredient and dispersants, then the slurry is milled in a horizontal bead mill with 0.8–1.2 mm zirconium oxide beads at 2,000–3,000 rpm for 2–4 h. Terminal finished product types: suspension concentrate formulations of fungicides, herbicides, and insecticides for dilution in field spray tanks. Operational boundary: post-milling addition is preferred only as a tank-mix antifoam; addition before high-temperature accelerated storage at 54 °C for 14 days should be limited to 0.3% w/w to avoid particle aggregation.
Low-VOC acrylic latex paints receive 0.1–0.5% w/w L31 during the letdown phase of flat and semigloss formulations to reduce microfoam without solvating the coalescent. Foam density and bubble entrainment are evaluated using a spindle foam test at 2,000 rpm for 5 min and by drawdown film inspection for pinhole counts per 100 cm². Industry compliance: interior architectural coatings must conform to ISO 11998 for wet scrub resistance and, where sold in the EU, Directive 2004/42/EC VOC limits; defoamer components are reviewed under EU REACH. Formulation addition ratio: 0.1–0.5% w/w based on total formulation. Downstream production process: the defoamer is introduced after pigment dispersion and before the final rheology modifier addition, under low-shear mixing at 500–800 rpm for 10–15 min to avoid over-defoaming that creates cratering. Terminal finished product types: interior wall paints, ceiling paints, and waterborne primer/sealers. Operational boundary: at addition above 0.7% w/w, gloss reduction of 5–10% can occur in semigloss finishes due to surface migration of the polyether; compatibility with silicone surfactants should be pre-tested to prevent dewetting.
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Designated as L31, the product is a linear polyoxyethylene-polyoxypropylene block polyether supplied as a 100% active, water-dispersible liquid defoamer for aqueous process streams where residual petroleum oil fractions and silicone films are technically undesirable. The molecule contains a central polyoxypropylene hydrophobic segment and terminal polyoxyethylene hydrophilic segments; the calculated HLB places it in the low-foam surface-active range. The average molecular weight by gel-permeation chromatography is approximately 1,100 g/mol. Incoming inspection of ISO 9001 batch records typically uses the parameters shown in Table 1 for lot acceptance.
| Parameter | Test method | Typical range | Unit |
|---|---|---|---|
| Appearance | visual | colorless to pale yellow liquid | — |
| Kinematic viscosity at 25 °C | ASTM D445-21 | 160–175 | mm²/s |
| Density at 20 °C | ASTM D1298-12 | 1.015–1.025 | g/cm³ |
| Pour point | ASTM D97-17 | -32 | °C |
| Cloud point, 1 wt% aqueous | ASTM D2024-09 | 32–42 | °C |
| Hydroxyl number | ASTM D4274-21 | 45–55 | mg KOH/g |
| Water content | ASTM E203-16 | ≤0.10 | wt% |
| HLB, calculated | Griffin equation | 1.0–7.0 | dimensionless |
The cloud point of the 1 wt% aqueous dilution falls between 32 °C and 42 °C depending on EO/PO distribution, and the liquid exhibits a kinematic viscosity of 160–175 mm²/s at 25 °C. This combination permits injection through standard positive-displacement metering pumps without solvent dilution, but suction-side pressure should remain above 0.15 MPa to avoid cavitation because the viscosity slope flattens below 10 °C. The low hydroxyl number indicates a terminal primary hydroxyl content that is available for coupling but does not dominate the surface activity.
The performance boundary in high-electrolyte white water is set by the phase-inversion temperature of the ethylene oxide block. At temperatures below the 1 wt% cloud point, the polyether exists primarily as hydrated unimers in the bubble lamella. At or above the cloud point, dehydration of the polyoxyethylene block increases spreading pressure at the air-water interface, while the polyoxypropylene block associates with hydrophobic furnish contaminants. This dual affinity accelerates film thinning and Plateau-border drainage. Because the transition occurs over a narrow band of 32–42 °C, paper-machine white water at 38–46 °C places the polymer near its phase inversion. Mill trial data from a twin-wire machine operating at 1,150 m/min with 0.8 vol% entrained air indicated that 20–50 ppm active L31 reduced headbox air content to 0.2–0.3 vol% within 15 min; below 30 ppm, residual microfoam remained on the fiber mat. Published data for this specific configuration is limited, and dosage should be re-established with a dynamic drainage analyzer.
Dissolved salts depress the cloud point. A 5 wt% sodium chloride background can lower the phase-inversion point by 10–20 °C, so a dose of 30 ppm at 40 °C may be above the cloud point in one white-water loop and below it in another at 30 °C. The ASTM D2024-09 cloud-point test on deionized water therefore does not replace a cloud-point measurement on the actual process liquor.
In air-sparged recirculating loops, low-shear metering of undiluted L31 below 10 °C has produced cavitation in single-diaphragm metering pumps rated for 0.1–10 L/h. Dilution to 10–20 wt% active with demineralized water at 20–30 °C reduces viscosity sufficiently while avoiding premature phase separation. Continuous injection into the suction side of a centrifugal pump or into the vortex of a vacuum deaerator is preferred over batch addition directly to a wire pit, because local over-deaeration can create porosity defects in the sheet. For textile jet dyeing, 20–50 ppm on bath weight suppresses foam in high-turbulence venturi nozzles; addition above 100 ppm may re-stabilize foam through micellar solubilization, a boundary commonly observed with nonionic defoamers. Relative to high-EO block polyethers such as L64 and F68, L31 has a lower ethylene-oxide mass fraction of approximately 10 wt%. This shifts the cloud point downward and increases the spreading pressure at the foam film in warm process streams. A 40 wt% EO block polyether remains water-soluble over a broader temperature band and can act as a foam stabilizer in the same application. Therefore L31 is selected for deaeration rather than wetting.
Unlike mineral-oil defoamers, L31 carries no petroleum distillate fraction and leaves no free oil film on stainless steel dryer cylinders if white water carryover reaches the drying section. On high-speed paper machines operating above 1,200 m/min, mineral-oil droplets can coalesce into deposits on ceramic suction-box covers and press felts; L31 partitions into the aqueous phase below its cloud point and does not form a separate oil layer. The trade-off is knock-down speed. In a 60-second sparge test conducted with ASTM E2407-04, a 0.1 wt% silicone emulsion may collapse 90% of foam within 10 seconds, while L31 at 0.2 wt% may require 20–30 seconds. For systems with residence time above 60 seconds, this kinetic difference is generally acceptable. Published data for this specific comparison is limited; selection should be made with a plant-scale dynamic foam cell.
| Selection criterion | L31 EO/PO block polyether | Mineral-oil defoamer | Silicone emulsion |
|---|---|---|---|
| Silicone content | absent | absent | present |
| Petroleum oil fraction | absent | present | absent or carrier oil |
| Cloud point phase inversion | 32–42 °C | not applicable | not applicable |
| Water dispersibility at 25 °C | turbid microdispersion | poor, requires shear | milky emulsion |
| Typical active dosage in paper white water | 20–200 ppm | 50–500 ppm | 5–50 ppm |
| Film residue risk on coated board | low | moderate | high if overdosed |
| Knock-down speed in sparge test | moderate | moderate-fast | fast |
In metalworking fluid sumps, L31 does not introduce a tramp-oil layer, which reduces the frequency of sump-side oil skimming. However, its defoaming action is temperature-dependent; at 15 °C the polymer may remain more water-soluble and less surface-active, requiring a dose 1.5–2.0 times higher than at 35 °C when evaluated by ASTM E2407-04. This differs from silicone emulsions, which maintain activity over a wider temperature range but contribute to paint cratering if transferred to coated stampings.
The absence of polydimethylsiloxane eliminates crater defects in solvent-free acrylic coating formulations when L31 is used at 0.1–0.3 wt% on total formulation. In a 60 μm wet-film drawdown on corona-treated polyester, a silicone-type defoamer at 0.1 wt% produced visible fish-eye defects under 200 lx inspection, while L31 at 0.2 wt% produced no surface defects, although air release required 10–15 minutes under vacuum. For coatings applied over aluminum substrates, L31 does not interfere with ASTM D3359-17 cross-cut adhesion at 0.1–0.2 wt%. At pH below 2, hydrolytic cleavage of the polyether backbone can occur slowly in aqueous dispersion over 6-month storage; therefore silicone-free formulations should be evaluated for long-term hydrolytic stability. Published data for this specific configuration is limited, and laboratory panels are recommended before mill trials.
Closed-loop cooling water and high-pressure spray-washer applications require alkalinity and hardness control. In spray washers operating at 80–90 °C, L31 at 50 ppm suppresses foam but can form a thin inverse-soluble film on heat exchanger surfaces if calcium hardness exceeds 400 ppm as CaCO3. The film is removable with hot water below the cloud point. The product is not recommended for potable-water or direct food-contact foam control unless the specific grade is listed under 21 CFR 176.170 or 21 CFR 176.210; L31 is not a food additive. In fermentation broths containing proteins, the defoaming threshold may increase to 100–500 ppm because proteins compete for the air-water interface; sparge testing with actual broth is required before final dose selection.
Cloud point is determined by ASTM D2024-09 on a 1 wt% solution in deionized water; the L31 range is 32–42 °C, but lot-to-lot reproducibility can be ±2 °C. Incoming inspection should include kinematic viscosity by ASTM D445-21, because viscosity drift above 175 mm²/s at 25 °C can indicate high-molecular-weight fraction or water ingress. Hydroxyl number by ASTM D4274-21 should remain 45–55 mg KOH/g; lower values suggest degraded or oligomeric content. The product should be stored in stainless steel or high-density polyethylene at 5–40 °C. Exposure to air at temperatures above 120 °C can generate peroxides; nitrogen blanketing is recommended for bulk tanks. Avoid strong oxidizing agents, anhydrous chlorides, and concentrated mineral acids.
In closed-loop paper machine white water, the defoamer can be consumed by adsorption onto recycled fiber fines; at ash levels above 20 wt%, the effective residual may decline more rapidly than in wood-free systems. Operators should monitor entrained air using TAPPI T 519 om-92 or an equivalent optoelectronic probe at the headbox. Batch-to-batch variance in surfactant carryover from deinked pulp can shift the effective cloud point by 2–5 °C; a weekly cloud-point check on a settled white-water filtrate is therefore more useful than relying solely on the deionized-water certificate value. Published data for this specific configuration is limited. The practical lower-temperature limit for reliable pumping is 5 °C, because viscosity rises steeply below that point, while the upper storage limit of 40 °C preserves the cloud point and minimizes oxidative color development.
