SLES 28% – жидкий моющий средства и посудомоечная основа

The product identified as SLES 28% – Liquid Detergent & Dishwash Base is an aqueous anionic surfactant solution of sodium lauryl ether sulfate, INCI Sodium Laureth Sulfate, CAS 9004-82-4, with a nominal active matter of 28% by mass. The model designation used throughout this technical description is SLES-28 LDD; manufacturer-specific commercial codes vary but refer to the same 28% active ether sulfate platform. The material is supplied as a clear to slightly hazy, pale yellow liquid with a mild fatty alcohol odour and is positioned for direct incorporation into manual dishwash liquids, hard-surface cleaners, and liquid laundry detergents. The product is already neutralised and does not require the caustic neutralisation step associated with alkylbenzene sulfonic acid.

Specifications are typically grouped around an active matter window of 27.5–28.5%, a pH of 7.0–9.0 as received, and a residual sulfate content controlled to prevent viscosity drift. The presence of approximately 2 mol ethylene oxide per mole of fatty alcohol distinguishes the ether sulfate from straight sodium lauryl sulfate: the ethoxy chains raise tolerance to hard-water calcium ions and lower the Krafft point, reducing precipitation in cold liquid formulations. These properties directly affect use as a base for dishwash liquids in which clarity at 5°C and viscosity control with sodium chloride are process-critical.

What Distinguishes the 28% Active Grade from 70% SLES Pastes During Bulk Transfer and Storage?

Bulk receiving and process design for the 28% grade differ from 70% SLES paste primarily because of rheological behaviour at ambient temperature. A 70% paste typically requires heated storage at 30–40°C or an inline dilution skid to become pumpable, whereas the 28% grade can be transferred at 10–35°C using standard rotary lobe, progressive cavity, or centrifugal pumps. Supplier technical bulletins commonly report Brookfield viscosity below 2,500 mPa·s at 20°C for the 28% grade; the corresponding 70% paste frequently exceeds 15,000 mPa·s under identical spindle conditions. The handling benefit is therefore the elimination of heat tracing and heated storage for some production lines, but the delivered mass per active kilogram is higher.

The dilution economics should be evaluated on a dry-active basis. Formulating to 12% active anionic matter in a 1,000 kg batch requires 428.6 kg of SLES-28 at 28% active, compared with 171.4 kg of SLES-70 at 70% active. The resulting volumetric increase affects storage tank sizing and freight mass. In exchange, the 28% grade avoids the metered hot dilution step and reduces the risk of gel-phase stratification that can occur when 70% paste is added too rapidly to cold water without sufficient shear.

Storage should be in closed tanks constructed from 316L stainless steel or high-density polyethylene. Carbon steel is not recommended because the surfactant may promote metal surface wetting and under-deposit corrosion. Recirculation lines should be sized for low-shear or laminar flow; continuous high-shear recirculation can entrain air and produce stable foam blankets in the headspace. At 5°C, the product may become slightly turbid, but a short recirculation at 10–15°C typically restores visual clarity without active matter loss.

Product Specification Ranges and Analytical Test Methods

The table below summarises commonly reported certificate-of-analysis parameters. Limits may vary by supplier and should be fixed in the purchasing specification rather than inferred from generic data.

In a 5,000 L jacketed mixing vessel fitted with a turbine agitator, the addition sequence for a dishwash base should place SLES-28 after neutralized LABSA and before amphoteric betaine. This sequence prevents exposure of the ether sulfate to concentrated acid. At pH below 4.0, acid-catalysed hydrolysis of the ether sulfate linkage can reduce active matter and generate fatty alcohol ethers, which may appear as haze or cause odour drift. Neutralized LABSA, typically pH 7–9 after sodium hydroxide addition, should be cooled to below 45°C before SLES-28 is added; higher temperatures accelerate oxidation and can deepen colour, especially in the presence of trace iron.

The product can be used as the sole anionic surfactant in economy manual dishwash but is more commonly co-formulated with linear alkylbenzene sulfonate at an active matter ratio of 1:1 to 3:1 SLES-28:LABSA. The ratio balances foam volume, grease-cutting, and skin mildness. Production-scale batch records show that final viscosity depends more on the salt response of the mixed anionic system than on the viscosity of the individual raw materials.

Sodium sulfate is not merely a diluent in this product; it contributes to the initial ionic strength of the batch. Because the salt curve in a mixed anionic/amphoteric system is sensitive to total electrolyte, the sulfate content of each incoming batch should be subtracted from the sodium chloride budget. A batch produced with a high-sulfate supplier lot at 1.5% sodium sulfate may require 0.2–0.4% less sodium chloride than a low-sulfate lot at 0.5%, even if active matter remains constant. This lot-to-lot shift is a common cause of viscosity deviation in production when the purchasing specification lacks an upper sulfate limit.

When SLES 28% Replaces Sodium Lauryl Sulfate Powder in a Cold-Mix Dishwash Line

Conversion from sodium lauryl sulfate powder to the 28% ether sulfate changes material handling from a dust-controlled powder induction unit to a liquid metering system. SLS powder is typically supplied at ≥90% active matter and requires a high-shear disperser to prevent lump formation; SLES-28 can be introduced through a positive-displacement metering pump directly into the main mix vessel. The cost per active kilogram is higher for the liquid grade because water and freight are included, but the elimination of dust extraction, wetting time, and powder bridging can reduce batch cycle time on an existing liquid line.

Formulation differences extend beyond handling. SLS powder tends to produce a lower initial foam volume in hard water and can precipitate as the calcium salt; SLES-28 maintains clarity at water hardness up to 150–300 mg/L CaCO₃ depending on concentration and temperature. In manual dishwash liquids, the ether sulfate is selected when a denser, less irritant foam profile is required. The trade-off is that the 2 mol EO distribution shifts the micellisation behaviour; no universal critical micelle concentration value should be applied across suppliers because the alkyl chain distribution and ethylene oxide distribution vary among feedstock sources.

In a transfer from powder to liquid, the most frequent production defect is overshooting final viscosity due to the preconceived salt requirement. Because the liquid grade already contains water and can carry sodium sulfate from the sulfation process, the effective salt content of the raw material must be included in the thickening calculation. A batch that performed at 1.8% added sodium chloride with SLS powder may require only 1.0–1.4% added salt with SLES-28 when the same total active matter is used. The adjustment is made by preparing a 25% NaCl stock solution and dosing it under agitation at 0.1% increments, with Brookfield LVT viscosity checked at 25°C, spindle 2, 12 rpm after deaeration.

Process conflicts arise when the salt curve is approached from the high side. Beyond the plateau maximum, further salt addition can cause viscosity collapse or gel formation, depending on betaine ratio and perfume type. Reversing an over-thickened batch is possible only by dilution and rebuild with additional surfactant, which shifts active matter and may require re-preservation. Published data for this specific configuration is limited; therefore, each production site should generate a salt-response curve for its fixed perfume and preservative system.

Viscosity after manufacture should be measured at 25°C after deaeration because entrained air can suppress the reading by 10–30% in low-viscosity dishwash bases. The result is compared against a production control chart based on Brookfield LVT, spindle 2, 12 rpm, with a defined immersion depth and beaker diameter. Without fixed spindle, speed, and temperature, viscosity values are not transportable between batches or plants.

In manual dishwash performance testing, foam stability is evaluated under soil load using modifications of DIN 53902 or internal panel tests. The ether sulfate often shows lower initial flash foam than sodium lauryl sulfate but better foam retention in the presence of oily soil at comparable active matter. This behaviour is formulation-dependent; published comparative data for the 28% liquid base versus other feedstocks is limited, so process development should rely on standardised foam measurements with the target perfume and water hardness.

Relative to alpha-olefin sulfonate at equivalent active matter, SLES-28 has lower colour and milder odour but lower stability in strongly alkaline builders. In a liquid laundry application in which the finished pH is maintained above 10.5, alpha-olefin sulfonate or secondary alkane sulfonate may be preferred because the ether sulfate may undergo gradual hydrolysis. Conversely, in transparent dishwash at neutral pH, SLES-28 can deliver lower-temperature clarity and better compatibility with betaines than secondary alkane sulfonates.

Because the 28% grade contains approximately 72% water, it is not intrinsically self-preserving in bulk storage. Storage tanks should be vented through 0.2 µm filters or nitrogen blanketed. In-drum shelf life is typically 12 months at 5–35°C; lower temperatures may produce temporary turbidity, while repeated freeze-thaw cycles are not recommended. Microbiological stability of the finished product should be confirmed by ISO 11930 challenge testing when preservatives are selected. The anionic active matter by ISO 2271 should be measured on every received batch, and the pH should be re-checked after prolonged storage above 30°C because ester hydrolysis can lower pH gradually.

Regulatory data for the ether sulfate class indicate ready biodegradability under OECD 301F; however, finished-product claims depend on the full formulation and regional detergent regulation. Suppliers should provide REACH registration numbers for the exact substance and tonnage band. The 1,4-dioxane residual should be controlled through the sulfation process and specified as needed for the target market; if the finished product is covered by cosmetic or personal care limits, a limit of ≤30 mg/kg is commonly requested, but the detergent grade is not automatically certified to cosmetic monograph limits.