Section
| HS Code | 426835 |
| Product Name | KS-540 High-Alkali Self-Emulsifying Silicone Defoamer |
| Appearance | milky white viscous liquid |
| Active Content | 30±1% |
| Viscosity 25c | 1500-3500 mPa·s |
| Ph Value 1 Percent Solution | 7.0-8.5 |
| Ionic Type | nonionic |
| Self Emulsifying Property | forms stable microemulsion upon stirring with water |
| Water Dispersibility | fully dispersible in hard water and high-alkali solutions |
| Alkali Resistance | stable in up to 20% NaOH solution without demulsification |
| Temperature Resistance | effective and stable at 0-100°C |
| Defoaming Speed | rapid knock-down foam control |
| Foam Suppression Duration | long-lasting in high-alkali media |
| Compatibility | compatible with anionic, cationic, and nonionic systems |
| Shelf Life | 12 months in original sealed packaging |
As an accredited KS-540 High-Alkali Self-Emulsifying Silicone Defoamer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | KS-540 defoamer is packaged in 25 kg, 50 kg, or 200 kg drums, with sealed lids for safe transport and storage. |
| Container Loading (20′ FCL) | 20′ FCL loading: 80 drums (200kg each) or 16,000kg net, securely palletized and containerized for safe transport. |
| Shipping | Shipped in sealed plastic drums or IBC totes, protected from moisture, sunlight, and freezing. Containers must remain upright, secure, and clearly labeled. Store at 5–35°C in original packaging. Not classified as dangerous goods for road, sea, or air transport under standard conditions. Avoid contact with strong acids or oxidizers. |
| Storage | Store KS-540 in a sealed, original container in a cool, dry, well-ventilated area away from direct sunlight, heat, and incompatible materials. Maintain temperatures between 5°C and 35°C. Avoid freezing and extreme humidity. Ensure container remains tightly closed to prevent contamination or separation. Use appropriate personal protective equipment when handling. |
| Shelf Life | Store in original container, away from extreme temperatures. Shelf life is 12 months from manufacture date when unopened. |
Continuous kraft digesters operating at 170–175°C and white liquor effective alkali 18–22% release black liquor soap and lignin-derived surfactants after pressure letdown in blow tanks and during recirculation through falling-film evaporators. KS-540 is introduced at the weak black liquor feed tank or directly into the evaporator recirculation loop at an addition ratio of 0.10–0.50 kg active defoamer per tonne of black liquor dry solids, with the upper range reserved for concentrator units running above 65% solids. Compliance for food-contact paper and board falls under FDA 21 CFR 176.200 for defoaming agents used in paper and paperboard manufacture and FDA 21 CFR 176.170 for components contacting aqueous and fatty foods, supported by EU Regulation (EC) No 1935/2004, Article 3, and BfR Recommendation XXXVI for paper and board. In a typical production flow, the defoamer is metered after blow tank entrainment screens and before the first evaporator effect, allowing self-emulsifying silicone droplets to disperse at the air–liquid interface without being stripped by high-shear centrifugal pumps. The addition controls foam carryover in evaporator effects, reduces condenser fouling, and lowers black liquor entrainment into condensate streams. Terminal products include kraft linerboard, white-top testliner, bleached softwood market pulp, and grease-resistant paper. Operational boundary: residence time in white liquor at pH above 13.5 and temperature above 90°C should not exceed 8–12 h, because slow alkaline hydrolysis of siloxane bonds reduces interfacial activity. Direct injection into digester circulating liquor is not recommended because extreme residence time and high dissolved solids destabilize the emulsion before it reaches the foam interface.
At fabric speeds of 60–80 m/min, continuous open-width peroxide bleaching lines use pad-steam saturators containing 30–40 g/L NaOH and 10–20 g/L H2O2, a chemical matrix that strips conventional antifoam emulsions and destabilizes larger silicone droplets through creaming and coalescence. KS-540 is maintained at 0.3–1.0 g/L in the saturator trough, with the lower addition ratio applied to knitted cotton/elastane jersey at 120–180 g/m² and the upper ratio to heavy woven cotton sheeting at 250–350 g/m². The defoamer is added after the trough overflow return rather than directly into the padder nip; nip pressures of 2–4 bar impose high shear that can split self-emulsifying droplets and temporarily reduce foam knockdown. Compliance for global textile chemical supply includes ZDHC MRSL Version 3.1, OEKO-TEX Standard 100 Annex 4 residue limits, and GOTS Version 7.0 for certified organic wet processing. Process integration covers pad-steam open-width ranges, jigger bleaching batches, and high-temperature kier boiling for tubular cotton at 110–125°C and a liquor ratio of 1:6–1:10. Terminal finished textile forms are mercerized cotton sheeting, compact-spun jersey for activewear, and scoured nonwoven rolls for medical converting. An operational limitation appears with anionic optical brightener baths; unhydrolyzed silicone droplets can compete at the interface and should be introduced only after the brightener bath has reached full solubility. Batch-to-batch variation in cotton wax content shifts foam lead-in time, so alkali-stable defoamer dosing must be adjusted when free fatty acid load in the bath exceeds 200 mg/L as calcium stearate equivalent.
Sodium metasilicate-based industrial parts washer concentrates at pH 12.5–13.5 generate persistent foam from saponified metalworking lubricants, corrosion inhibitors, and fatty acid soils when the bath is held at 70–85°C. KS-540 is formulated into the concentrate at 0.05–0.30 wt%; after dilution of 1:50–1:100, the active working concentration is 1–6 ppm. The application is less concerned with cotton bath surface coverage than with suppressing nozzle backpressure and pump cavitation in spray systems operating at 1.5–2.5 bar. In conveyorized cabinet washers, the defoamer must remain dispersed in the sump where returning spray liquid churns through the extraction screen; addition at the sump return rather than the dosing tank prevents localized high concentration that can leave silicone residue on machined surfaces. The regulatory frame for placing the formulated detergent on the European market is EU Detergents Regulation (EC) No 648/2004, Annex VII, with voluntary environmental criteria under Commission Decision (EU) 2017/1217 for industrial cleaners. The production path for this application is inline blending of the silicone defoamer into the cooling phase of the detergent concentrate at 40–50°C after solubilizing the metasilicate and surfactant package. Finished goods include alkaline degreaser concentrates, CIP additives for dairy processing, and bottle-wash detergents for returnable glass lines. It should not be combined with hypochlorite stock solutions above 10% active chlorine because oxidative cleavage of the siloxane chain generates low-molecular-weight silanols with diminished defoaming response.
When mixed liquor suspended solids exceed 8,000 mg/L in membrane bioreactors, filament-associated foam and extracellular polymeric substance monolayers stabilize fine bubbles and reduce oxygen transfer in fine-bubble diffuser lanes. KS-540 is dosed at 1–10 ppm active on aeration basin volume, with the established control window at 3–5 ppm for MLSS 8,000–12,000 mg/L; above that threshold, biofloc adsorption and hydrophobic partitioning can require a two- to three-fold increase to achieve the same foam knockback. The defoamer is metered into the scum channel return or directly ahead of the fine-bubble diffuser bank, not into the membrane tank backflush line, because permeate-side adsorption on PVDF membranes is minimized only when the silicone is attached to mixed liquor solids. The relevant compliance frame is not a finished product standard but discharge and ecotoxicity assessment under EU Water Framework Directive 2000/60/EC and ready biodegradability screening under OECD 301F. The downstream production process includes submerged flat-sheet PVDF modules operated at 20–30 LMH flux, anoxic/oxic denitrification, and chemically enhanced primary clarification for phosphorus precipitation. Finished outputs are treated industrial effluent for indirect discharge, dewatered activated sludge for co-processing, and high-quality permeate for reverse osmosis polishing. Published data for this specific configuration in high-alkali textile effluent is limited; plant-level confirmation of dose-response is therefore performed using a bubble column sparge tube with foam height measured according to an internal method after 10 min aeration. Overdosing above 20 ppm active can depress oxygen transfer coefficients by more than 10% and should be avoided unless airflow is increased accordingly.
A twin-shaft paddle mixer processing a polycarboxylate ether high-range water reducer concrete batch can show air content above 6.0 vol% before KS-540 is introduced. The defoamer is added at 0.02–0.10% by cement weight, typically after the high-range water reducer has been dispersed for 60–90 s; adding it before the dispersant forces the silicone droplets to compete with the polycarboxylate ether for cement particle surfaces, producing variable slump and surface voids. The production process is either a twin-shaft batch mixer with 1.0–1.5 m³ batch volume or a pan mixer for precast segments, both operating at 20–30 rpm during the critical defoamer incorporation window. In this application KS-540 collapses large entrained air voids while preserving the spaced sub-300 µm void structure required for freeze–thaw resistance. Compliance for the formulated admixture follows EN 934-2:2009, Table 1, and where applicable ASTM C494/C494M Type S for specific performance. Terminal finished product types include self-compacting concrete for architectural façades, precast railway sleepers, and pumpable screed underlayments. The main operational boundary is that dosage above 0.20% by cement weight can reduce air content below 2.0 vol%, which degrades freeze–thaw durability measured by ASTM C666/C666M; the defoamer should not be blended with air-entraining admixtures in a single dosing line before the mixing cycle because immediate coalescence of the air-entraining surfactant monolayer negates the air-void spacing factor.
In conveyorized spray washers operating at 1.5–2.5 bar nozzle pressure and 80°C sodium hydroxide baths, foam is generated from saponified metalworking fluids, rust-preventive residues, and amine-based corrosion inhibitors. KS-540 is fed at 0.05–0.20 vol% of sump volume continuously through a dosing pump into the recirculation line after the bag filter, not into the spray manifold, to avoid localized silicone concentration on workpieces. The high-alkali environment is within the product stability window because self-emulsifying droplets resist rapid phase separation in 5% NaOH, but the operational boundary for post-wash coating adhesion requires that silicone carryover on parts be removed in a separate overflow rinse stage; residual silicone films above 1–3 mg/m² can interfere with subsequent zinc phosphate conversion and electrophoretic coating. The compliance benchmark for the formulated metal cleaner is EU CLP Regulation (EC) No 1272/2008; when evaluating oil separation from the bath, ASTM D1401-18 applies for water-miscible metalworking fluids, and ISO 4406:2021 is used for recirculating bath particle counts. Terminal production pieces are stamped steel brackets, cast aluminium housings, and stamped battery trays prepared for cathodic electrocoat or powder coating. An inline 25–40 kHz ultrasonic stage can be used after spray washing to remove foam-trapped soils, but the defoamer must be added before the ultrasonic tank, not after, so that coalesced bubbles do not damp transducer cavitation. Field experience on continuous belt washers indicates that foam carryover into the drag-out zone is reduced when the defoamer feed rate is tied to sump conductivity rather than fixed timer pulses.
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Prior to release, each production lot is characterized against the parameters shown in Table 1. The active silicone content is determined gravimetrically after volatile removal, the viscosity is measured under controlled shear conditions using a Brookfield LV spindle configuration, and the freeze-thaw resistance is assessed using cyclic temperature exposure adapted from waterborne coatings methodology.
| Parameter | Specification Value | Test Method |
|---|---|---|
| Appearance | White to off-white viscous liquid | Visual inspection |
| Silicone active content | 23.0 ± 1.5 wt% | ISO 3251 |
| Viscosity at 25°C | 1,200–2,400 mPa·s | ISO 2555, Brookfield LV spindle 3 at 30 rpm |
| Density at 25°C | 0.99–1.02 g/cm³ | ISO 2811-1 |
| pH as supplied | 6.5–8.0 | ISO 976 |
| Ionic character | Nonionic | — |
| Water dispersibility | Spontaneous, complete at 1:100 dilution, 25°C | Visual dilution test |
| Alkali stability (static) | No phase separation after 72 hours in 10 wt% NaOH at 25°C | Internal static jar test |
| Freeze-thaw stability | 3 cycles from −5°C to 25°C without irreversible creaming | Adapted from ASTM D2243 |
| Shelf life | 12 months in sealed original container at 5–35°C | — |
The self-emulsifying mechanism of KS-540 in water at the point of addition is governed by the phase inversion behavior of the nonionic emulsifier system, which is formulated within an HLB range of 8–12. When the supplied macroemulsion is diluted at ratios between 1:10 and 1:1000 in aqueous process fluid, the continuous phase of the macroemulsion is progressively replaced by process water; the system passes through a bicontinuous sponge phase before discharging into a kinetically stable oil-in-water microdispersion. Laser diffraction measurements on diluted samples conducted according to ISO 13320 typically yield median droplet diameters of 3–8 µm, with a D90 below 20 µm, which is the accepted size window for effective foam-film bridging without visible surface oiling. Droplets larger than 50 µm are associated with fisheye defects in coated textiles and silicone spotting on metal surfaces; droplets below 0.5 µm exhibit insufficient spreading volume per droplet to destabilize mature foam lamellae. This droplet size distribution remains reproducible across tap water, deionized water, and process water containing up to 15 wt% NaOH, demonstrating the electrolyte insensitivity of the steric stabilization mechanism. In quiescent bulk storage, the supplied emulsion exhibits a low-shear viscosity suitable for diaphragm or peristaltic pumping; thixotropic recovery after pumping prevents separation. The product can be prediluted down to 1:100 and held for 24 hours without creaming, permitting preparation of feed tanks in advance of dosing shifts.
The alkali tolerance of KS-540 is rooted in the chemical structure of the dispersed silicone phase and the deliberate exclusion of hydrolysable functional groups. The siloxane backbone bond energy, approximately 452 kJ/mol for the Si–O linkage, exceeds that of ester linkages at approximately 358 kJ/mol found in mineral oil and vegetable oil defoamer carriers; consequently, saponification of the defoamer carrier phase, a primary deactivation pathway for fatty acid ester-based products at pH above 12, is unavailable to KS-540. Alkali-catalyzed depolymerization of polydimethylsiloxane does proceed via siloxane bond cleavage, but the reaction rate under process conditions of 10–15 wt% NaOH and temperatures below 90°C is negligible over residence times up to 8 hours. This permits use in continuous alkaline scouring operations without incremental dosing to compensate for hydrolytic loss. A further design feature is the nonionic emulsifier package: the surfactant headgroups are polyethylene oxide chains whose ether linkages resist alkaline hydrolysis at temperatures below 120°C, and the absence of anionic sulfate or sulfonate headgroups avoids sodium-ion-induced electrostatic screening and subsequent droplet coagulation in high-ionic-strength media. By contrast, conventional anionic silicone emulsions exhibit visible phase separation within 24 hours when placed in 10 wt% NaOH at 25°C, a failing mode documented in industrial pretreatment trials. Published comparative performance data for KS-540 in this specific alkali concentration range is limited; however, the structural basis for its stability is well established in silicone emulsion science.
In continuous open-width alkaline scouring of cotton and cotton-blend fabrics, the process bath typically contains sodium hydroxide at 20–40 g/L (0.5–1.0 mol/L), a caustic-stable wetting agent at 0.5–2.0 g/L, and operates at 70–95°C. Foam generated in the saturator, steamer, and washing compartments disrupts uniform liquor pickup and can carry alkali into subsequent bleaching stages, causing uneven hydrogen peroxide activation. KS-540 is metered directly into the scouring saturator at a rate of 0.02–0.05 wt% of the working bath volume, using either diaphragm dosing pumps or flow-proportional injection systems. The self-emulsifying property eliminates the need for a separate dilution tank; however, for baths where circulation shear is below 0.5 m/s flow velocity, a preliminary dilution of 1:10 in softened water is recommended to ensure rapid distribution. Persistence of defoaming action in the steamer is assessed using a recirculating pump foam test conducted according to ASTM E2407, which measures foam volume under continuous aeration and provides a comparative ranking for dosage adjustment at mill scale. On pad-steam ranges and rope-scouring J-boxes, dosages above 0.1 wt% generally provide no additional defoaming benefit and increase the risk of silicone deposition on fabric surfaces during subsequent mercerizing. The product is compatible with common scouring auxiliaries including sodium silicate, sodium carbonate, and nonylphenol-free caustic-stable wetting agents.The comparative matrix in Table 2 positions KS-540 against four defoamer classes under identical high-alkali exposure conditions. The entries reflect typical class-level behavior reported in technical bulletins and peer-reviewed assessments of defoamer performance in alkaline media; specific lot-to-lot variation within each class may occur. Alkali tolerance refers to visual phase stability after 72 hours in 10 wt% NaOH at 25°C; self-dispersibility describes behavior upon addition to water at 15°C without agitation beyond gentle mixing.
| Property | KS-540 | Conventional anionic silicone emulsion | Mineral oil defoamer | Polyether siloxane | Polyglycol |
|---|---|---|---|---|---|
| Alkali tolerance (10 wt% NaOH, 72 h, 25°C) | No phase separation | Coagulation or creaming | Saponification | Viscosity increase, slow hydrolysis | Phase separation |
| Self-dispersibility in cold water (15°C) | Spontaneous | Requires pre-dilution and agitation | Poor | Good | Excellent |
| Typical dosage, wt% of process fluid | 0.02–0.10 | 0.05–0.30 | 0.10–0.50 | 0.05–0.30 | 0.50–2.0 |
| Surface deposition risk on fabric/metal | Low | Moderate to high | High | Low | Moderate |
| Foam persistence under continuous aeration (ASTM E2407) | High | Moderate | Low | Moderate | Very low |
| Compatibility with anionic wetting agents | Good | Variable | Poor | Good | Good |
The failure of conventional anionic silicone emulsions under these conditions is attributable to electrostatic destabilization: sulfate and sulfonate headgroups undergo charge screening at sodium-ion concentrations above approximately 2 mol/L, collapsing the electrostatic repulsion barrier and permitting droplet coalescence. Mineral oil defoamers fail through chemical conversion of their ester and fatty acid carriers into soap byproducts that act as foam stabilizers rather than foam breakers—an inversion of function that escalates foam volume in recirculating systems. Polyether siloxanes exhibit better alkali tolerance than ester-based products but undergo gradual siloxane backbone cleavage at pH above 13, reducing their defoaming persistence in long-residence-time applications. Polyglycol defoamers, while fully water-soluble and easy to handle, require dosages one to two orders of magnitude higher and provide limited foam knockdown in high-air-entrainment processes.
Weak black liquor from softwood pulping typically retains an effective alkali concentration of 5–15 g/L NaOH equivalent (pH 12.5–13.5) and contains dissolved lignin, resin acid soaps, and fatty acid soaps that function as potent foam stabilizers. Foam generation in weak black liquor storage tanks, brownstock washer filtrate loops, and evaporator feed systems reduces heat transfer coefficients and can cause carryover of black liquor solids into the condensate train. KS-540 is introduced at a dosage of 0.01–0.03 wt% on dry black liquor solids, either at the filtrate tank or into the washer shower water, using positive-displacement metering pumps tolerant of high-viscosity fluids. The self-emulsifying mechanism is operationally significant in this environment because conventional silicone compounds can form floating oil lenses on the black liquor surface, which are then entrained into the oxidation stage and contribute to screen deposition. The nonionic surfactant system of KS-540 does not react with dissolved kraft lignin or with the sodium resinate content to form insoluble complexes, avoiding the pitch deposition problems associated with cationic polymer-based antifoams. Published data for defoamer performance specifically within black liquor solids above 70% dry solids is limited; for evaporator stages operating above 70% solids, dosage optimization is recommended through sparge testing with actual process liquor rather than relying on water-based foam test data. In bulk storage, KS-540 is maintained in sealed HDPE containers or stainless-steel totes at temperatures between 5°C and 35°C. Exposure to freezing conditions below −5°C can produce irreversible creaming; if frozen inadvertently, the material is not recovered by heating above 40°C or by violent agitation. The product should not be combined with concentrated oxidizing agents such as sodium hypochlorite, 50% hydrogen peroxide, or peracetic acid, because these oxidize the silicone phase and generate silica deposition layers on equipment surfaces. In wastewater treatment applications, co-addition with high-molecular-weight cationic polyelectrolytes such as polyDADMAC can induce flocculation of the emulsifier micelles and is therefore avoided. The material is formulated without added preservatives; because the as-supplied pH of 6.5–8.0 supports microbial growth, drums should be kept tightly sealed and partially used containers should be consumed within 90 days. For continuous dosing applications, feed lines should be short and constructed of PVC, EPDM, or stainless steel; silicone rubber gaskets are unsuitable because the product's PDMS phase causes swelling and loss of seal integrity in silicone elastomer components. These operational boundaries address the failure modes most frequently observed in industrial defoamer handling systems.
