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SLES 70% Paste – Low Dioxane Grade
- Product Name: SLES 70% Paste – Low Dioxane Grade
- Factroy Site: Yudu County, Ganzhou, Jiangxi, China
- Price Inquiry: sales4@ascent-chem.com
- Manufacturer: Ascent Petrochem Holdings Co., Limited
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- In terms of specification, SLES 70% Paste – Low Dioxane Grade is supplied with an active matter content of 70 ± 1% w/w and a 1,4-dioxane content ≤ 20 ppm, making it suitable for rinse-off personal care cleansing formulations requiring low-dioxane surfactant quality.
| HS Code | 932180 |
| Product Name | SLES 70% Paste – Low Dioxane Grade |
| Chemical Name | Sodium Lauryl Ether Sulfate |
| Cas Number | 9004-82-4 |
| Appearance | White to pale yellow viscous paste |
| Active Matter Content | 70% by weight |
| Ph 1 Aqueous Solution | 6.5 - 8.5 |
| Viscosity At 25 C | 1000 - 4000 mPa·s |
| 1 4 Dioxane Content | ≤ 30 ppm |
| Sodium Sulfate Content | ≤ 1.5% |
| Unsulfated Matter Content | ≤ 2.0% |
| Moisture Water Content | Approximately 30% |
| Color Apha | ≤ 50 |
| Density At 20 C | 1.05 - 1.10 g/cm³ |
| Ionic Nature | Anionic surfactant |
| Solubility | Soluble in water, forming a clear solution |
As an accredited SLES 70% Paste – Low Dioxane Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Available in 170 kg HDPE drums or 1,000 kg IBC totes for SLES 70% Paste Low Dioxane Grade. |
| Container Loading (20′ FCL) | 20′ FCL loading of SLES 70% paste (low dioxane) in drums, securely palletized and strapped for safe transport. |
| Shipping | SLES 70% Paste – Low Dioxane Grade is supplied in 230kg HDPE drums, IBCs, or bulk tankers. Suitable for sea, road, and rail transport with standard export packaging. Store in a cool, dry, ventilated area away from heat. Use proper PPE during handling. |
| Storage | Store in tightly sealed HDPE or epoxy-lined containers in a cool, dry, well-ventilated area away from direct sunlight. Keep temperatures below 40°C to prevent phase separation or degradation. Protect from moisture and humidity, as the paste is hygroscopic. Avoid contact with acids, oxidizers, and incompatible materials. Maintain good housekeeping to prevent spills and contamination, ensuring product stability throughout its shelf life. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored sealed in cool, dry conditions away from extreme temperatures. |
In rinse-off personal cleansing formulations, low-dioxane SLES 70% paste is introduced as the primary anionic surfactant at 8–12 wt% active matter, typically combined with cocamidopropyl betaine at 2.5–3.5 wt% active and cocamide MEA at 0.8–1.2 wt%. The thickening response to sodium chloride is non-linear: below 0.4 wt% added NaCl, micellar charge repulsion dominates and Brookfield viscosity remains below 1,500 cP at 25°C in a 12 wt% active SLES/CAPB 3:1 blend. As NaCl is raised from 0.4 wt% to 1.1 wt%, rod-like micelle formation produces a viscosity increase of 4,000–7,000 cP per 0.1 wt% NaCl, and the target finishing viscosity of 12,000–18,000 cP at spindle 4, 12 rpm is typically reached between 1.0 wt% and 1.3 wt% added NaCl. Addition beyond 1.8 wt% NaCl reverses the build, collapsing to below 6,000 cP and producing a white turbidity that marks the upper boundary of the salt window. The paste must be pre-diluted to 25–30 wt% active before cold addition to the main batch; direct dosing of the 70% paste into water below 15°C generates local gel lumps requiring high-shear recirculation through a Silverson inline rotor-stator fitted with a slotted screen, often consuming 35–45 min of post-blend homogenisation. In hard water of 250 ppm CaCO₃, flash foam height is reduced by approximately 18% relative to deionised water, an effect counteracted by raising the CAPB ratio to 1:2.5 and increasing disodium EDTA to 0.15 wt%. Preservative selection is constrained by the high surfactant phase: phenoxyethanol at 0.8 wt% partitions into micelles and loses aqueous activity, while methylchloroisothiazolinone/methylisothiazolinone 3:1 at 0.05 wt% active retains log-reduction values above 5 against Pseudomonas aeruginosa in ISO 11930 preservative challenge when formulation pH is held at 5.2–6.0. At pH above 7.5, the low-dioxane grade displays a 30–40% reduction in free preservative concentration due to anionic charge changes independent of the dioxane content.
| Parameter | Method/standard | Typical control |
|---|---|---|
| Anionic active matter | ISO 2271 two-phase titration | 69.5–70.5 wt% |
| 1,4-dioxane | USP <228> headspace GC–MS | ≤10 mg/kg |
| Ready biodegradability | OECD 301B | ≥60% ThOD in 28 days |
| pH, 5% aqueous dilution | ISO 4316 | 7.0–9.0 |
| Colour, Hazen, neat paste | ISO 6271 | ≤30 |
What Controls Phase Stability When NaCl Climbs Past 1.4 wt% in a 70% Paste Dilution?
Hand dishwashing liquids formulated with low-dioxane SLES 70% paste are typically compounded at 10–14 wt% active SLES in the finished product, with total anionic-active matter of 16–20 wt% when combined with sodium lauryl sulfate and sulfosuccinates. Phase stability at 5°C and 45°C storage is governed by the sodium chloride threshold relative to hydrotrope concentration. At 1.4 wt% NaCl, a clear isotropic phase persists only when sodium cumene sulfonate or sodium xylene sulfonate is maintained at 2.0–4.0 wt% active; without hydrotrope, the cloud point falls below 25°C and a surfactant-rich phase separates. Viscosity is generally controlled to 800–2,500 cP, measured with a Brookfield LV spindle 2 at 30 rpm, to permit clean flow from a standard trigger-spray or flip-top cap. The 70% paste is diluted to 28–32 wt% active before addition to a vessel at 35–40°C; high-shear mixing above 900 rpm entrains air and increases batch aeration. The formulation pH is held at 6.5–7.5 because acidification below 5.5 promotes sulfate ester hydrolysis during 12-week shelf storage at 40°C, generating free fatty alcohol that lowers cloud point. Grease-cutting performance, measured by a modified Gardner straight-line wash method with 3 wt% soybean oil soil, improves when sodium citrate or tetrasodium EDTA at 0.5–1.0 wt% is present; however, excess builder above 1.5 wt% displaces water of hydration and induces stringy texture. The low dioxane level permits use in mass-market dish liquids where 1,4-dioxane in finished goods is controlled under USP <228> headspace GC–MS at ≤10 mg/kg.
When a 12% Active Solution Meets Subtilisin Protease at pH 9.2
Liquid laundry detergent systems use low-dioxane SLES 70% paste as a secondary anionic co-surfactant at 3–6 wt% active, paired with linear alkylbenzene sulfonic acid neutralised to sodium LAS at 6–10 wt% active and C12-C15 alcohol ethoxylate 7EO at 3–5 wt%. At wash-liquor dilution of 1:800, the SLES concentration falls below 0.15 g/L, at which point subtilisin protease retains more than 85% of its casein digestion activity after 30 min at 40°C, measured by a modified Anson method. At 0.4 g/L, inhibition rises to 30–40%, which defines the upper practical concentration for enzyme-containing laundry products. pH 9.2 is maintained with monoethanolamine or sodium carbonate; the sulfate ester group of SLES undergoes 2–3% hydrolysis over 8 weeks at 40°C at pH 9.2, acceptable for liquid detergents, but exceeding pH 10.5 increases hydrolysis to 8–10% and releases alcohol insolubles. Protease inhibition in the early wash cycle is minimised by adding 0.3–0.6 wt% sodium formate and 0.05–0.15 wt% calcium chloride as stabiliser; calcium ion binding reduces the denaturing interaction between anionic surfactant head groups and the protease active site. Low-dioxane SLES is preferred in liquid detergent manufacture because the paste is handled as a 70% active feed at 35–40°C, and any residual 1,4-dioxane introduced into wash water would not be removed by conventional wastewater treatment at the municipal level.
During emulsion polymerisation of styrene–butyl acrylate and vinyl acetate–ethylene lattices, low-dioxane SLES 70% paste functions as the primary anionic stabiliser at 1.0–2.5 wt% based on total monomer. The surfactant critical micelle concentration in deionised water is approximately 300 mg/L at 25°C, and the reactor charge is typically prepared as a 5 wt% aqueous solution before monomer pre-emulsion. Particle nucleation follows a micellar mechanism when the free-surfactant concentration exceeds the CMC; final latex particle size distribution narrows from 220 nm to 150 nm as measured by ISO 22412:2017 dynamic light scattering as SLES level increases from 1.0 wt% to 2.5 wt%, but residual serum surface tension drops below 35 mN/m and secondary nucleation increases coagulum above 0.05% on a 100-mesh screen. The polymerisation is run in a glass-lined jacketed reactor with pitched-blade turbine at 120 rpm, using ammonium persulfate initiator at 0.4–0.6 wt% based on monomer and sodium metabisulfite redox at 0.2–0.3 wt%. Temperature is held at 78–82°C for styrene–butyl acrylate and 60–65°C for vinyl acetate–ethylene. pH is buffered to 4.5–5.5 with sodium bicarbonate; below pH 3.0, SLES hydrolyses to dodecanol and sulfate, causing odour in the latex film. The low-dioxane specification avoids transfer of 1,4-dioxane into the final dispersion, which is relevant for coated paper and textile binder applications where residual volatile impurities are regulated by the purchaser.
Alkaline Builder Saturation and Immersion Degreaser Cloud Point Behavior
Industrial immersion degreasers formulated with low-dioxane SLES 70% paste at 2–5 wt% active in the working bath require a narrow alkaline window because sulfate ester hydrolysis and cloud-point shifts impose parallel failure modes. Sodium metasilicate pentahydrate at 1.5–3.0 wt% raises working pH to 9.5–10.3 and improves oil emulsification, but total builder salinity must not exceed 3.5 wt% or the surfactant-rich phase separates within 24 h at 45°C. Tetrasodium EDTA at 0.5–1.0 wt% chelates calcium; sodium hydroxide above 2 wt% is incompatible with prolonged bath life because ester linkage hydrolysis releases lauryl alcohol and lowers detergency, with observed extraction of dirty motor oil soil dropping by 15–20% after 72 h at 55°C in a 10-cycle immersion test. Foam height in a 2 L Ross-Miles apparatus under ASTM D1173 at 49°C exceeds 100 mm at 2.5 wt% active SLES, requiring an EO/PO block copolymer defoamer at 0.05–0.20 wt% for parts-washer use. Below 0.8 wt% active SLES, the bath loses reserve detergency and oil redeposition onto metal surfaces becomes measurable by gravimetric panel difference of 0.4–0.6 g/m² per cycle.
Kier Boiling and Low-Foaming Scouring Ranges for Cellulose Substrates
Textile wet processing uses low-dioxane SLES 70% paste as a wetting agent in continuous cotton scouring and as a leveling assistant in exhaust dyeing, often at 0.3–2.0 g/L active in the working bath. In open-width scouring, 1.0–2.0 g/L SLES combined with sodium hydroxide 18–25 g/L at 95–100°C lowers surface tension to 28–30 mN/m and improves cotton seed husk removal, measured gravimetrically after desizing and bleaching. Foam generation is a boundary condition: above 2.5 g/L active, bath foam height exceeds 100 mm in a 2 L Ross-Miles apparatus and forces addition of silicone emulsion antifoam at 0.5–1.0 g/L. In polyester exhaust dyeing with disperse dyes, SLES at 0.3–0.8 g/L promotes dye bath stability and prevents oligomer redeposition on fibre surfaces; however, at acidic pH 4.5 and 130°C, sulfate hydrolysis is accelerated, therefore bath hold time in acid conditions is limited to 60 min per cycle. The low 1,4-dioxane content is relevant in textiles for children’s garments where residual surfactant may remain after washing.
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- SLES 70% Paste – Low Dioxane Grade is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
- COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales4@ascent-chem.com.
Designated as an aqueous anionic surfactant paste, SLES 70% Paste – Low Dioxane Grade consists of sodium laureth sulfate with an average ethoxylation of 2 moles ethylene oxide per mole fatty alcohol, an alkyl chain distribution centered on C12–C14, and nominal active-matter content of 68–72 %. The material identity is sodium lauryl ether sulfate, CAS RN 68891-38-3, with INCI name sodium laureth sulfate. The low-dioxane designation describes a process-grade class produced by post-sulfation vacuum stripping of the neutralized paste, so that residual 1,4-dioxane is controlled at ≤ 10 mg/kg rather than the 20–100 mg/kg range commonly reported for standard sulfated ethoxylate pastes. The product model code is supplier-specific; the low-dioxane suffix does not alter the sulfated surfactant backbone, the unsulfated matter specification, or the electrolyte response. Its primary position is as a primary anionic surfactant in rinse-off cleansing formulations, liquid laundry and dish detergents, and industrial hand cleaners where high active matter and reduced by-product levels are specified in raw-material quality protocols.
Table 1. Representative release specification for SLES 70% Paste – Low Dioxane Grade.
| Parameter | Method | Specification |
|---|---|---|
| Active matter | ISO 2271 | 68–72 % |
| Unsulfated matter | ISO 8799 | ≤ 2.5 % |
| Sodium sulfate | ISO 6844 | ≤ 1.5 % |
| pH, 2% aqueous solution | ISO 4316 | 7.0–9.0 |
| 1,4-Dioxane | Headspace GC-MS, US EPA Method 8260D | ≤ 10 mg/kg |
| Colour, platinum-cobalt scale | ISO 6271 | ≤ 30 |
What Drives Residual 1,4-Dioxane in Sulfated Ethoxylate Pastes?
Residual 1,4-dioxane is not added to SLES; it forms as an intramolecular cyclization by-product during sulfation of the ethoxylated fatty alcohol. The mechanism involves acid-catalyzed back-biting of the ethylene oxide chain under the conditions of sulfur trioxide or chlorosulfonic acid sulfation. The rate of formation increases with free acid concentration, localized reactor temperature, and residence time in the falling-film sulfation unit. After neutralization with sodium hydroxide or sodium carbonate, the already-formed dioxane remains in the paste unless a dedicated stripping operation is installed. Standard SLES 70% pastes are therefore sold with residual dioxane concentrations commonly reported between 20 mg/kg and 100 mg/kg; low-dioxane grades reduce the value to ≤ 10 mg/kg, and some supplier codes specify ≤ 5 mg/kg for high-end cosmetic raw material programs.
The stripping step exploits the vapour pressure difference between 1,4-dioxane, with an atmospheric boiling point of 101 °C, and water under reduced pressure. Supplier technical bulletins describe wiped-film or thin-film evaporators operated at moderate temperature and reduced pressure; exact pressure, residence time, and condenser design are process-specific and not disclosed in most published literature. The important product consequence is that the sulfated active matter is not altered: the molecular weight distribution, the average ethylene oxide number, and the anionic titration response remain aligned with standard SLES 70% paste. Published engineering data for thin-film stripping of SLES paste specific to low-dioxane grades are limited; most technical evidence is confined to supplier specification sheets and headspace GC-MS release data.
For release control, 1,4-dioxane is quantified by static headspace gas chromatography with mass-selective detection. A representative sample preparation equilibrates a diluted paste aliquot at 60 °C in a sealed vial; selected-ion monitoring of m/z 88 and m/z 58 provides quantification limits around 1–5 mg/kg in surfactant matrices. The use of US EPA Method 8260D or an equivalent isotope-dilution procedure is standard because direct injection GC-FID gives poor reproducibility at ≤ 10 mg/kg due to co-eluting surfactant-related volatiles.
Regulatory exposure to 1,4-dioxane is constrained by Article 17 of Regulation (EC) No 1223/2009, which addresses unavoidable traces of prohibited carcinogenic, mutagenic, or reprotoxic substances. 1,4-Dioxane is not an intentional cosmetic ingredient; its presence as a technical impurity is minimized under good manufacturing practice. The California Office of Environmental Health Hazard Assessment lists 1,4-dioxane under Proposition 65; use of a low-dioxane SLES raw material is one element in reducing final exposure, although the finished-product concentration also depends on other ethoxylated raw materials and water quality. If the paste is used at 10 wt% active matter and contains ≤ 10 mg/kg 1,4-dioxane, the theoretical maximum contribution from this raw material is 1 mg/kg in the concentrate before additional dilution or contribution from other ingredients.
Handling requirements for the low-dioxane grade do not differ from standard 70 % SLES paste. The material is shear-thinning; an apparent viscosity value without spindle and speed is not comparable between suppliers. Bulk storage uses 316L stainless steel or high-density polyethylene-lined vessels. Viscosity increases sharply below 15 °C; warming to 30–40 °C under low-shear recirculation restores transfer viscosity. The sulfate ester linkage is hydrolytically unstable at pH below 2.0 and at sustained temperatures above 80 °C; therefore the paste is held at its native pH 7.0–9.0 and not blended with concentrated mineral acids. Contact with strong oxidizers is avoided because cleavage of the ether sulfate releases fatty alcohol ethoxylate and inorganic sulfate.
When Low-Dioxane Paste Enters Cold-Process Surfactant Systems
In cold-process manufacturing, the water phase is maintained at 20–30 °C and the paste is added to water under agitation, not reverse-added. Production-scale vessels fitted with counter-rotating anchor agitators and side scrapers at 30–60 rpm, followed by a short high-shear dispersion step of 5–10 min, prevent localized hydration gel lumps. The paste is typically diluted to 10–15 % active matter for a rinse-off cleansing base. Sodium chloride is added at 0.5–2.0 wt% of batch to build viscosity; the salt curve passes through a maximum and then falls with further electrolyte. The peak position depends on active-matter content and co-surfactant ratio, not on the dioxane stripping step, because the stripping operation does not alter the alkyl chain distribution or the sulfate ester density.
Foam height is measured by the Ross–Miles method under ISO 696. Direct published comparative foam-height data for low-dioxane versus standard SLES 70% paste are limited; equivalence is inferred from the unchanged active-matter content and ethoxylation distribution. Formulations targeting 4,000–8,000 mPa·s at 25 °C measured by Brookfield RVT spindle 5 at 20 rpm can be obtained with the same electrolyte levels as standard SLES. No additional salt is introduced by the vacuum stripping process because the manipulated variable is the volatile fraction, not the inorganic sulfate content.
Typical use levels in rinse-off formats are 5–15 % active SLES as the primary anionic surfactant, adjusted with co-surfactants such as cocamidopropyl betaine at 1–4 % active to modify foam quality and viscosity build. The low-dioxane grade is compatible with nonionic alkyl polyglucosides and amphoteric systems; compatibility with high-charge-density cationic polymers requires charge screening because anionic–cationic complexation can precipitate in the mixing tank. In hard water, the ethoxylate spacer of SLES produces a calcium-ion tolerance profile different from non-ethoxylated sodium lauryl sulfate; calcium chloride precipitation tests are used to quantify that difference, although published data specific to this low-dioxane grade are limited.
Microbial control in the 70 % paste relies on low water activity rather than added preservatives. Closed vessels exclude external contamination. Once diluted below 20 % active matter for use, the aqueous system is susceptible to bacterial, yeast, and mold growth; a preservative system selected for surfactant compatibility is added. The low-dioxane grade does not modify the preservative demand because the stripping step does not add a biocide or alter pH. Batch-to-batch variation in dioxane content is monitored by headspace GC-MS; typical release testing uses a limit of quantitation of 5 mg/kg against a specification of ≤ 10 mg/kg to avoid rejecting material due to analytical noise.
Specification Divergence and Equipment-Release Comparisons
Where the low-dioxane grade diverges from a standard SLES 70% paste is in the residual 1,4-dioxane specification and, in some supplier datasheets, colour. Table 2 compares representative databook ranges; supplier-specific values may differ.
| Parameter | Standard SLES 70% Paste | Low-Dioxane SLES 70% Paste | Analytical Method |
|---|---|---|---|
| 1,4-Dioxane | 20–100 mg/kg | ≤ 10 mg/kg | Headspace GC-MS, US EPA Method 8260D |
| Active matter | 68–72 % | 68–72 % | ISO 2271 |
| Unsulfated matter | ≤ 2.5 % | ≤ 2.5 % | ISO 8799 |
| Sodium sulfate | ≤ 1.5 % | ≤ 1.5 % | ISO 6844 |
| pH, 2% aqueous solution | 7.0–9.0 | 7.0–9.0 | ISO 4316 |
| Colour, platinum-cobalt scale | ≤ 50 | ≤ 30 | ISO 6271 |
The comparative data show that actives, unsulfated matter, and sulfate remain within the same release windows. This is expected because dioxane stripping removes a volatile by-product; it does not remove sulfated active matter. The low-dioxane grade should not be confused with sodium lauryl sulfate or sodium coco-sulfate. Sodium lauryl sulfate is not ethoxylated and therefore does not generate dioxane by the same route, but it has a different alkyl sulfate structure and different hard-water and irritation profile. Sodium coco-sulfate may contain a different chain distribution. The low-dioxane SLES 70% paste also differs from SLES 28% liquid low-dioxane grades in water content and logistics: the 70 % paste reduces transport water and has lower water activity in closed storage, while 28 % liquid is easier to pump at ambient temperature and may require a preservative system after dilution.
Supplier naming conventions vary. Some codes use “SLES 70% LD,” “SLES 70% low dioxane,” or “SLES 70% cosmetic grade with low 1,4-dioxane.” The common technical discriminator is the residual dioxane release limit and the analytical method. A purchaser should require a batch-specific certificate of analysis showing active matter by ISO 2271 and 1,4-dioxane by headspace GC-MS; periodic dioxane screening alone is not equivalent to lot-wise release testing.
The vacuum stripping unit introduces a process cost and can extend batch time; published data on equipment throughput are limited. The production bottleneck is typically the thin-film stripping capacity rather than the sulfation reactor, because the paste must be held at elevated temperature long enough to remove dioxane without triggering ester hydrolysis. This creates a narrower finishing window than standard paste. If the temperature is pushed above 80 °C to accelerate stripping, the sulfate ester hydrolysis rate increases; if the temperature is too low, stripping time increases and batch throughput falls. Supplier data sheets do not always disclose this window; production-scale observations are seldom published in consolidated form.
Transfer piping for cold paste should be designed for high viscosity at 15–20 °C. Positive-displacement pumps, such as progressive-cavity or lobe pumps, are used rather than centrifugal pumps because the paste has high low-shear viscosity and poor suction behaviour at ambient temperature. Heating jackets on transfer lines are set to 30–40 °C to reduce pressure drop without reaching hydrolysis-prone temperatures.
pH is measured in 2 % aqueous solution under ISO 4316. The paste has a high pH due to residual alkalinity from neutralization; this alkalinity must be acid-adjusted in finished formulations to 5.0–6.5 to match skin pH and optimize preservative performance. Citric acid or lactic acid are used; strong mineral acids are avoided because localized low pH can hydrolyze the sulfate ester before bulk mixing is complete.
Low-dioxane stripping may also remove a portion of other low-molecular-weight volatile by-products, including acetaldehyde and short-chain aldehydes, which can alter the headspace odour profile of the raw material. Published sensory data are limited and not standardized; odour comparison is typically evaluated by a trained panel using a defined dilution protocol. The reduction in dioxane is analytically quantified, but odour differences should not be assumed without panel data because residual odour can originate from the fatty alcohol feedstock rather than from sulfation by-products.
Occupational exposure to 1,4-dioxane in the low-dioxane paste is reduced relative to standard paste, but process ventilation and skin-contact controls are still governed by the surfactant paste properties rather than by the trace dioxane content alone. The paste is an eye and skin irritant at high active matter; pH 7.0–9.0 does not preclude irritation from the surfactant itself. Eye protection and impervious gloves are required when handling undiluted paste; the safety data sheet remains the control document.
The phrase “low dioxane” is not equivalent to “dioxane-free”; analytical detection limits mean that absence cannot be demonstrated. Specifications therefore use a positive release limit of ≤ 10 mg/kg or ≤ 5 mg/kg, not zero.