Section
| HS Code | 388235 |
| Product Name | L68 EO/PO Block Polyether Defoamer |
| Physical Form | Flake Solid |
| Chemical Composition | EO/PO block copolymer polyether |
| Appearance | White to light yellow flake solid |
| Ionic Type | Nonionic |
| Cloud Point | 17–21 °C (1% aqueous solution) |
| Melting Point Range | 40–50 °C |
| Moisture Content | ≤ 0.5% |
| Ph 1 Aqueous Solution | 5.0–7.0 |
| Active Content | 100% |
| Hlb Value | 10–12 |
| Solubility | Soluble in water |
| Foam Suppression Property | Destabilizes and suppresses foam in aqueous systems |
| Thermal Stability | Stable under normal processing temperatures |
As an accredited L68 EO/PO Block Polyether Defoamer (Flake Solid) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged as flake solid in 25 kg multi-layer paper-plastic composite bags with PE liner, palletized and stretch-wrapped for safe transport. |
| Container Loading (20′ FCL) | 20′ FCL: palletized L68 EO/PO flake solids, moisture-protected, securely stowed, ventilated, and prevented from contamination or crushing. |
| Shipping | L68 EO/PO Block Polyether Defoamer (Flake Solid) ships as a non-hazardous solid in sealed polyethylene-lined bags or fiber drums. Keep dry, away from moisture and direct sunlight, during transport. Avoid excessive pressure; store in ventilated area at ambient temperature. Standard truck or container shipping is suitable. |
| Storage | Store L68 EO/PO Block Polyether Defoamer (flake solid) in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep the original container tightly sealed to prevent moisture absorption and contamination. Avoid storage near strong oxidizers. Maintain ambient temperature to preserve product performance; use within recommended shelf life. |
| Shelf Life | Shelf life is typically 24 months when stored in a cool, dry place in unopened, sealed packaging. |
In post-tower powder detergent finishing, the L68 EO/PO block polyether defoamer in flake solid form is typically handled as a dry additive rather than as a predispersed liquid. It is metered from a twin-screw loss-in-weight feeder into a continuous paddle mixer or a rotating drum blender after the spray-dried base powder has cooled below the flake softening point stated in the lot certificate. The process conflict on production-scale spray towers is the temperature mismatch between the tower heat load and the flake’s phase behaviour: spray tower air inlet temperatures of 250–350°C and slurry ring-main temperatures above 60°C make slurry-side addition operationally unreliable. If the flake is charged into the crutcher slurry before spray drying, partial melting and phase inversion can occur, leading to feed-pump cavitation and uneven distribution in the finished powder. For this reason, post-tower addition is the preferred processing route. The addition ratio for heavy-duty laundry powder is 0.2–0.8 wt% of the post-tower detergent base, with the lower end used for low-foam machine powders and the upper end reserved for short-cycle washing conditions where foam carry-over must be suppressed quickly. Finished formulations placed on the EU market must comply with Regulation (EC) No 648/2004; although the flake is not a surfactant for detergency purposes, it must not compromise the finished product’s compliance, and inherent biodegradability is normally screened according to OECD 302B. Foam performance is commonly evaluated by ASTM D1173-07, with dynamic foam collapse measured in a SITA foam tester R-2000 rather than relying only on static cylinder observations. Terminal finished goods include heavy-duty laundry powders, compact detergent tablets, and industrial laundry powder supplied to hospital and contract laundering operations. Batch-to-batch variance in flake particle size distribution requires feeder recalibration, especially when the post-tower blending drum operates above 45°C or residual moisture exceeds 8 wt%; published data for this specific flake configuration is limited, so mill-scale trials determine the exact moisture and temperature boundaries.
For non-food aerobic fermentation, the flake solid is prepared as a 5–10 wt% aqueous dispersion in a jacketed stainless steel make-down vessel at 40–50°C and is dosed into the foam layer via a peristaltic pump activated by a foam probe mounted in the bioreactor headspace. The working dosage is normally 0.01–0.05 vol% based on working liquid volume, but the actual set point is trimmed against dissolved oxygen and headspace foam height because broth ionic strength and extracellular protein concentration shift the defoamer’s performance. Production fermentation is carried out in stainless steel bioreactors fitted with pitched-blade Rushton turbines delivering 1–3 kW/m³ specific power input and an air sparge rate of 0.5–1.0 vvm; dissolved oxygen is held at 30% saturation during the fed-batch growth phase. The defoamer must collapse surface foam without forming a continuous oil layer that reduces the volumetric oxygen transfer coefficient kLa. For this reason, the maximum allowable addition rate is not fixed; it is validated by kLa decay measurement before full production. The fermentation plant for industrial enzymes and fuel ethanol operates under Regulation (EC) No 1907/2006 (REACH) with workplace exposure assessed according to EN 689:2018. No food-contact approval is implied for this use; if the target product is a food enzyme, the formulation would require regulatory review, and no self-approval under FDA 21 CFR 173.340 should be assumed. Terminal finished types are industrial cellulase and xylanase preparations, fuel ethanol, and non-food organic acid broths. Published data for this specific block polyether in high-protein broths is limited; however, phase separation above 0.1 vol% has been observed in pilot trials, and operators revalidate kLa after any lot change.
Black liquor foam in kraft pulping is controlled by dosing the flake solid as a 5–10 wt% aqueous dispersion into brownstock washer shower water, never as dry flake into high-consistency pulp because dry particles cannot reach the foam interface. The dosage window is 0.02–0.08 kg per tonne of dry fibre, adjusted by washer level sensors and dynamic foam test data rather than by fixed volumetric addition. The typical production route is kraft brownstock washing, closed screening, oxygen delignification, and bleach plant operation; foam carryover in this route reduces washer efficiency and can release sulfide-containing off-gas into the mill air system. Dosing after the pressure screen but before the washer shower header prevents hydrophobic deposition on forming fabrics while still collapsing black liquor foam. For food-contact paper and board, the defoamer is assessed under US FDA 21 CFR 176.170 and 21 CFR 176.200, EU Regulation (EC) No 1935/2004, and where applicable BfR Recommendation XXXVI. Mill-specific compliance is documented by extraction tests on the finished sheet, and a change in defoamer dose outside the stated band triggers re-testing for organoleptic transfer. Terminal finished products include linerboard, sack kraft, tissue basesheet, and food-contact folding carton board. The critical processing conflict is not foam alone but liquor entrainment: excessive defoamer can stabilise an inverse emulsion in the weak black liquor, making tall oil recovery less efficient; therefore the lower end of the dose band is preferred in mills with soap skimming.
High-temperature jet dyeing of polyester and polyester-cotton knits uses the flake solid as a pre-dispersed additive introduced into the dye bath addition tank, not directly into the fabric circulation loop. The bath concentration is maintained at 0.05–0.3 g/L, with the lower range used for pre-scoured cotton blends and the upper range used for densely knitted fabrics that trap air in the jet nozzle. The dyeing process operates at 130°C, a liquor ratio of 1:5–1:10, and a circulation rate of 2–4 L/kg·min, with backpressure held at 0.2–0.4 MPa. Under these conditions, uncontrolled foam in the machine sump leads to pump cavitation, fabric rope slippage, and uneven dispersion of disperse dyes. The defoamer is silicone-free and is selected to avoid hydrophobic spots on dark shades; exceeding 0.3 g/L can cause the polymer to deposit on fabric surfaces under high shear, producing specking in navy and black dyeings. Compliance for dyed textiles sold into the EU market is documented against OEKO-TEX Standard 100, ZDHC MRSL v3.1, and the bluesign system black list, and the defoamer must not contain substances that exceed the residual limits in these standards. Terminal finished products include polyester-cotton knit shirting, automotive seating textiles, and moisture-management sportswear. Because dyehouse effluent is treated for COD and surfactant load, any increase in defoamer dose above 0.3 g/L requires re-evaluation of the mill’s wastewater discharge permit parameters under the EU Urban Waste Water Treatment Directive 91/271/EEC.
In synthetic and semi-synthetic metalworking fluid concentrates, the L68 flake solid is introduced during the cool-down phase after neutralisation of the acidic lubricant package, at a dose of 0.05–0.2 wt% of the concentrate. The blending vessel is a stainless steel tank fitted with a high-shear disperser and a temperature jacket; the flake is first dissolved or finely dispersed in a glycol or glycol ether carrier, then added to the batch below 50°C. The production route includes mixing of alkanolamine-neutralised carboxylic acid corrosion inhibitors, addition of the phosphate ester EP package, incorporation of the defoamer carrier dispersion, and final filtration through a 10 µm bag filter before drumming. Concentrates are classified and labelled under CLP Regulation (EC) No 1272/2008, the product category is documented under ISO 6743-7, and foam performance of the diluted fluid is measured according to ASTM D3601-88(2019) in a blender test. The terminal fluids are soluble cutting fluids, grinding coolants, and high-pressure through-tool coolant systems where entrained air can cause pump chatter and tool starvation. The principal process limitation is inverse solubility: if the flake is added before the full amine-neutralisation step or at temperatures above 50°C, it may become solubilised into the concentrate and lose defoaming efficacy in the diluted fluid. Therefore, post-neutralisation addition and a controlled cool-down profile are treated as mandatory process controls in ISO 9001-documented blending operations.
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L68 EO/PO block polyether defoamer (flake solid) is a nonionic polyoxyethylene–polyoxypropylene block copolymer supplied as a solid flake for gravimetric dosing into aqueous foam-prone systems. The proprietary grade identifier L68 is a supplier-specific code; it does not correspond to the generic “liquid/paste/flake” lettering used in poloxamer nomenclature. The flake form combines low water activity with a high bulk density and permits direct addition to high-shear zones or batch preparation of stock solutions. The defoaming mechanism is thermal: below the cloud point the copolymer is water-dispersible; as the process temperature rises toward the cloud point, the poly(propylene oxide) block dehydrates and forms hydrophobic microdomains that spread at the air–liquid interface, reduce film elasticity, and destabilize foam lamellae. Because the chemistry contains no silicone and no mineral-oil carrier, it is used in fermentation, papermaking, textile dyeing, water treatment, pigment dispersion, and polymer emulsion processes where silicone residues or hydrocarbon oil extractables are not acceptable.
Lot release is controlled by the certificate of analysis. Purchasing specifications for flake-solid EO/PO block polyether defoamers of this class typically include cloud point by ISO 1065, hydroxyl number by ISO 14900:2017, acid value by ASTM D974, moisture by ASTM E203, pH by ASTM D1293, and melt range by ISO 11357-3. Representative framework values for this product class are moisture ≤1.0 wt%, acid value ≤0.5 mg KOH/g, pH 5.0–7.5 in 1 wt% aqueous dispersion, and a lot-specific cloud point commonly within 20–60°C. Because the EO/PO ratio and total molar mass are adjusted to the target application, lot-to-lot cloud point variation must be checked against the application temperature. Published data specific to the L68 designation is limited; the framework ranges originate from industrial flake-polyether defoamer specifications and do not replace the supplier’s technical data sheet.
Compared with liquid EO/PO block polyether defoamers, the solid flake form eliminates water or solvent payload, avoids freeze–thaw separation, and allows longer warehouse storage in sealed bags. Compared with fatty alcohol ethoxylate flake defoamers, the block copolymer architecture produces a sharper cloud-point transition and lower residual foam persistence after the initial knockdown. The flake format is also suited to gravimetric dosing in facilities without liquid chemical day tanks or diaphragm metering pumps.
Polydimethylsiloxane defoamers can reduce foam at mass fractions as low as 0.0005 wt%, but they may leave persistent silicone films that cause surface defects in coatings, printing inks, and adhesive lamination. Mineral-oil and vegetable-oil defoamers introduce organic load, can increase chemical oxygen demand, and may separate in high-pH or high-electrolyte streams. L68 is non-silicone and non-hydrocarbon; its cloud-point-driven mechanism does not deposit a mineral-oil slick. The trade-off is that L68 requires adequate dispersion and is temperature-sensitive; above the cloud point, hydrophobic particles can accumulate at vessel walls and on heat-exchanger surfaces. Comparative boundaries are shown in Table 1.
| Chemistry | Typical dosage (wt% of process fluid) | Principal failure risk | Screening method |
|---|---|---|---|
| L68 EO/PO block polyether flake solid | 0.005–0.2 | Under-dispersion; wall fouling above cloud point | ASTM D1173-23 |
| Polydimethylsiloxane emulsion | 0.0005–0.02 | Film-forming residue; adhesion loss | ASTM D1173-23 |
| Mineral oil/silicone blend | 0.01–0.3 | Chemical oxygen demand increase; oil carryover | ASTM D1173-23 |
| Vegetable oil/fatty acid ester | 0.01–0.5 | pH-dependent splitting; rancidity | ASTM D1173-23 |
The dosages in Table 1 are class-level ranges for aqueous foam control and are not product-specific. The lower effective dose for L68 must be established by foam-cell testing in the target process fluid, because soluble proteins, lignosulfonates, and anionic wetting agents shift foam stability and defoamer partitioning.
Before metering, L68 flakes are normally predispersed in water at a temperature at least 10–15°C below the cloud point. A 5–20 wt% stock solution is prepared in a stainless-steel or HDPE mix tank equipped with a slow axial-flow impeller at 60–120 rpm. Flake is introduced through a volumetric screw feeder into the vortex. Water temperature is held below the cloud point because localized hot spots can form a sticky, water-insoluble skin that blocks pump suction strainers. Once the flakes are wetted, centrifugal pump recirculation at low speed is sufficient; a high-shear disperser is not required and may entrain air.
In paper machine stock approach systems, direct flake addition is limited to pulpers, machine chest mixers, or fan-pump suction zones where hydraulic shear is high. Flakes added directly to the headbox or whitewater seal pit can pass to the wire as undissolved polymer, producing translucent spots and felt-filling deposits. A pressure-screen evaluation with a 500 µm slotted basket is used to detect undispersed flake carryover; repeated screen plugging indicates that predispersion is insufficient.
In fermentation, L68 is typically added to the broth at 0.01–0.1 wt% of initial batch mass when foam height exceeds the vessel freeboard limit. The flake solid is pre-dissolved in sterile water or in a side-stream of broth below the cloud point and fed through a sterilizable injection port. Antifoam demand in exponential growth phase can be up to three times higher than in stationary phase; automated foam sensors on the headspace or mechanical foam breakers are used to initiate dosing. Published data for L68 in specific microbial systems is limited; sparge-tube screening in the target broth is required because extracellular proteins and polysaccharides alter foam stability and defoamer partitioning.
On alkaline fine-paper machines, L68 is used in the wet end to control entrained air in the stock because entrained air can reduce headbox jet stability, slow drainage on the forming fabric, and create pinholes. It is preferred over silicone emulsions when the finished sheet is to be surface-sized or coated, because residual silicone can interfere with size-press pick-up and coating adhesion.
Once a 5 wt% stock solution is prepared, it is metered through a low-pulsation diaphragm or progressive cavity pump and diluted in a static mixer to 0.1–1.0 wt% before injection into the process stream. Undiluted stock solution injected into a cold stream can create local concentration gradients that reduce defoamer efficiency. The stock solution has a finite stability window of 24–72 h depending on water quality and biocide loading. In alkaline water above pH 9, polyether solutions may slowly oxidize and lose activity; long residence times in non-passivated steel tanks should be avoided. If microbial growth is visible or the solution becomes turbid, the batch should be discarded rather than filtered and reused.
Performance screening is conducted in a dynamic foam cell according to ASTM D1173-23. In that protocol, foam is generated by a diffuser stone in a jacketed vessel; foam height is recorded at 30 s, 60 s, and 300 s after the sparge starts. The defoamer is added when foam height reaches a fixed threshold, and the time to collapse below that threshold is recorded as knockdown time. In paper machine whitewater and fermentation broth, L68 typically shows stronger knockdown when dosed at the foam front than when mixed uniformly into the bulk liquid, because the hydrophobic particles must contact the lamellae directly. For high-fouling broths containing soluble protein, calcium, and lignosulfonate, addition rates may need to rise to 0.1–0.5 wt%; published data for this specific configuration is limited, and bench-scale foam-cell testing is required to establish the lower effective dose.
Foam control in vacuum pump service water is another application; here the flake is dissolved at 2–5 wt% in make-up water and metered into the cooling tower or seal-water return line. Because the defoamer is non-silicone, it does not form a tenacious film on heat-exchanger surfaces. In activated sludge basins, L68 is sprayed onto the foam surface at the point of worst accumulation. Surface spray application reduces the total mass required compared with bulk dosing, because the hydrophobic particles are concentrated at the foam interface. The use rate in municipal wastewater is typically below 0.01 wt% of basin volume; in industrial lagoons with high fatty-acid load from meat or dairy processing, higher doses are required. Overuse can reduce oxygen transfer efficiency; therefore, the minimum dose that controls foam is preferred.
The EO/PO block polyether backbone is stable in dilute neutral and alkaline aqueous media. Under hot acidic conditions below pH 4, particularly in the presence of strong oxidizers such as hydrogen peroxide or chlorine dioxide, oxidative chain scission can reduce molar mass and shift the cloud point. The product should not be combined with concentrated nitric acid, fuming sulfuric acid, or peracetic acid sterilant without compatibility testing. In high-electrolyte brines, cloud point is depressed; a system operating at 35°C can behave as if it is above the cloud point when salt content exceeds 10 wt%. This can be used deliberately to trigger defoaming, but it also increases wall-fouling risk. In such systems, the defoamer is injected into a high-flow recirculation line rather than into a stagnant vessel.
Compatibility with anionic wetting agents and lignosulfonates should be confirmed by a cloud-point shift test; high levels of anionic surfactants can increase the cloud point and delay the thermal defoaming trigger. This shift can move the effective defoaming temperature outside the original process window, requiring re-optimization of the dose point.
Storage boundaries are controlled by moisture and compaction. Flakes are hygroscopic; at relative humidity above 60%, the product can absorb sufficient water to soften and block screw feeders. Warehousing should be below 40°C, and opened bags must be re-closed under dry conditions. If clumping occurs, the material is dried at 35–40°C in a forced-air dryer to ≤1.0 wt% moisture before use. The material is not classified as flammable, but fine dust generated by grinding or pneumatic conveying may form a combustible dust cloud; conveying systems should be bonded and grounded in accordance with local dust hazard analysis requirements.
For food-contact paper and paperboard applications, the specific L68 grade must be verified against 21 CFR 176.170 and 21 CFR 176.180, because not every flake polyether is manufactured under food-contact quality systems. For general industrial use in the European Economic Area, the product must comply with REACH (Regulation (EC) No 1907/2006) registration and Safety Data Sheet obligations under Article 31. RoHS (Directive 2011/65/EU) does not normally apply to process chemicals, but downstream users in electronics fabrication should confirm that no restricted substance is introduced as a contaminant. No halogens are intentionally added.
Equipment cleanout of residual L68 is performed with warm water below the cloud point; hardened films are removed with hot water above the cloud point or with aqueous alkali at pH 10–12, followed by fresh water rinse. Waste streams containing the defoamer should be treated in normal biological wastewater systems; the product contributes organic load and may temporarily reduce oxygen transfer in aeration basins if slug-dosed. Discharge must be assessed against local permit limits.
