Textile
Stearyl Amine and Stearic Acid Ethoxylates: Cationic, Nonionic, and Emulsifier Chemistry
Stearyl (C18) derivatives represent important specialty surfactants bridging cationic, nonionic, and anionic behaviour. Stearyl amine ethoxylates combine cationic nitrogen character with nonionic EO chains, providing antistatic, softening, and emulsification functions. Stearic acid ethoxylates (PEG stearates) are purely nonionic esters used as emulsifiers, solubilizers, and thickeners. This guide covers the chemistry, properties, and applications of both families, with formulation examples for textiles, personal care, and industrial uses. Venus Ethoxyethers manufactures amine ethoxylates and PEG ester surfactants from Goa, India.
On this page
- Understanding the two families
- How they are manufactured
- Stearyl amine ethoxylates
- Stearyl versus tallow and coco amine ethoxylates
- Applications of stearyl amine ethoxylates
- Stearic acid ethoxylates (PEG stearates)
- Comparing amine ethoxylates vs acid ethoxylates
- Formulation examples
- Quality and specifications
- Troubleshooting
- Sourcing from Venus
Understanding the two families
Although both derive from stearyl (C18) feedstocks, stearyl amine ethoxylates and stearic acid ethoxylates are chemically distinct. Buyers sometimes request “C18 ethoxylate” without specifying amine versus acid; that ambiguity leads to the wrong ionic class, the wrong pH behaviour, and failed plant trials. Confirm whether the hydrophobe is stearyl amine (R–NH2) or stearic acid (R–COOH) before discussing EO moles.
| Property | Stearyl Amine Ethoxylate | Stearic Acid Ethoxylate (PEG Stearate) |
|---|---|---|
| Feedstock | Stearyl amine (C18H37–NH2) | Stearic acid (C18H36O2) |
| Bond to EO | N–EO (amine nitrogen) | Ester linkage (–COO–) |
| Ionic character | Cationic at low pH, nonionic at high pH | Purely nonionic |
| Typical HLB range | Variable by EO; often 8–14 | 11–18 depending on PEG MW |
| Primary functions | Antistat, softener, corrosion inhibitor | O/W emulsifier, thickener, solubilizer |
Stearyl amine ethoxylates sit inside the broader fatty amine ethoxylates family alongside tallow and coco grades. PEG stearates are covered in more INCI detail in the PEG stearate emulsifiers guide. For surfactant class context, see what is a surfactant and the cationic surfactants guide.
How they are manufactured
Stearyl amine is typically produced from stearic acid via the nitrile route: fatty acid reacts with ammonia to a nitrile, which is hydrogenated to the primary amine. That amine is then ethoxylated with ethylene oxide in pressurized reactors. EO adds to nitrogen, giving mono- and di-substituted polyoxyethylene chains. Catalyst, temperature, and mole ratio control average EO and colour. Low-EO products are often pastes; higher-EO grades are more water-soluble liquids or waxy solids.
Stearic acid ethoxylates (PEG stearates) are esters: stearic acid is reacted with polyethylene glycol of a chosen molecular weight, or stearic acid is ethoxylated under esterification conditions. The PEG chain length sets HLB. Moisture in the PEG feedstock and acid value of the fatty acid affect conversion and residual free acid — both appear on a quality COA. Venus runs alkoxylation and esterification on the same Goa platform, so amine ethoxylates and PEG esters can be sourced together with consistent documentation.
Stearyl amine ethoxylates
Fatty amine ethoxylates are produced by reacting primary or secondary amines with ethylene oxide. The nitrogen atom carries a lone pair that can accept a proton at low pH, making these surfactants cationic-capable. At neutral to high pH, the amine is unprotonated and behaves as nonionic.
Stearyl amine ethoxylates (C18 amine base) provide:
- Antistatic properties — cationic charge neutralizes negative surface charges on polymers and textiles
- Textile softening — substantivity to negatively charged fibres
- Corrosion inhibition — film-forming on metal surfaces
- Emulsification — particularly for bitumen, asphalt, and industrial oils
EO mole count determines water solubility and HLB. Low EO (2–5) grades are water-dispersible; high EO (10–15+) grades are water-soluble. Low-EO grades adsorb more strongly on cotton, polyester, and metal oxides; high-EO grades emulsify oils and wet hydrophobic surfaces more like a conventional nonionic. Do not mix low-EO amine ethoxylates directly with anionic surfactants in the same concentrated aqueous phase — precipitation and loss of activity result. High-EO grades tolerate anionics better at use dilution; jar testing remains mandatory.
Stearyl versus tallow and coco amine ethoxylates
Stearyl amine is a relatively defined C18 hydrophobe. Tallow amine is a C16–C18 mix from tallow triglycerides; coco amine is C12–C14 from coconut. Stearyl and tallow grades give stronger hydrophobic adsorption, better paraffinic and bitumen emulsification, and higher melting points. Coco grades wet faster, have lower viscosity, and dissolve more easily at the same EO level. If a textile softener needs maximum substantivity on synthetics, start with stearyl or tallow 2–5 EO. If an acid pickling inhibitor must dissolve quickly in HCl, coco 2–5 EO is often the more practical starting point. Venus manufactures tallow, coco, oleyl, and stearyl amine ethoxylates at custom EO levels — see also fatty amine ethoxylates and tallow amine ethoxylates.
Applications of stearyl amine ethoxylates
Textile softeners: Added to final rinse or finishing bath, amine ethoxylates impart soft handle and reduce static cling on synthetic fibres. Often combined with silicone softeners for enhanced effect. Typical exhaust on cotton knits is well below 1% o.w.f. of a diluted concentrate. Residual anionic soap from dyeing will reduce uptake — rinse first. Related wet processing: textile chemicals and cotton textile treatment.
Antistatic agents: Applied as surface treatment on plastics, films, and fibres to prevent dust attraction and spark discharge. Common in packaging, electronics, and automotive interior components. A thin adsorbed film raises surface conductivity enough to bleed charge; it is not a bulk conductive compound. Reapply after washing or severe abrasion.
Asphalt emulsifiers: Cationic amine ethoxylates are standard emulsifiers for cationic rapid-set (CRS) and cationic slow-set (CSS) asphalt emulsions used in road construction. The cationic character promotes adhesion to negatively charged aggregate. EO level and residual amine value are tuned so the emulsion breaks at the right time on the road: too stable and the mix will not set; too unstable and it breaks in the tanker. Specify the emulsion class (CRS vs CSS) when requesting a grade.
Corrosion inhibitors: Film-forming inhibitors for metal working fluids and fuel additives. Low-EO stearyl and tallow amines adsorb as oriented films on steel in acid and in some circulating waters at tens of ppm. See fatty amine ethoxylates guide for broader amine ethoxylate coverage and metal working chemicals for related industrial grades.
Stearic acid ethoxylates (PEG stearates)
Stearic acid ethoxylates — commonly called PEG stearates — are nonionic ester surfactants formed by reacting stearic acid with polyethylene glycol. The PEG molecular weight determines HLB and function:
| Grade | PEG MW | HLB (approx.) | Primary function |
|---|---|---|---|
| PEG-8 Stearate | ~400 | ~11 | Emulsifier, solubilizer |
| PEG-20 Stearate | ~1000 | ~15 | O/W emulsifier, coupling |
| PEG-40 Stearate | ~2000 | ~17 | Solubilizer, co-emulsifier |
| PEG-100 Stearate | ~5000 | ~18 | SLES thickener, mild emulsifier |
PEG stearates are widely used in personal care for cream and lotion emulsification, fragrance solubilization, and shampoo thickening. See PEG stearate emulsifiers guide for detailed formulation examples. PEG-100 stearate is frequently paired with glyceryl stearate as a self-emulsifying wax. PEG-40 and PEG-20 grades suit lighter lotions and solubilizer roles. Diester grades (not shown above) are more lipophilic and often used as thickeners rather than primary O/W emulsifiers. Explore personal care surfactants for related Venus chemistry.
Unlike amine ethoxylates, PEG stearates do not protonate. They remain nonionic from typical cosmetic pH 4–8 through mildly alkaline cleanser bases. Ester linkages can hydrolyse in prolonged high-pH, high-temperature storage — a reason not to use PEG stearate as the sole emulsifier in a 70°C, pH 12 industrial degreaser. For those baths, phosphate esters or alkali-stable nonionics are the correct class.
Comparing amine ethoxylates vs acid ethoxylates
- Cationic character: Only amine ethoxylates provide cationic behaviour — important for antistat, softening, and asphalt emulsion applications
- Emulsification: Both can emulsify, but stearic acid ethoxylates are preferred for cosmetic O/W systems due to mildness; amine ethoxylates suit industrial applications
- pH sensitivity: Amine ethoxylates change character with pH; stearic acid ethoxylates are stable nonionic across pH range
HLB still matters for both families. A stearyl amine 15 EO and a PEG-40 stearate can both emulsify an oil phase, but they will not give the same sensory profile, substantivity, or compatibility with anionics. Choose ionic class first, EO/PEG length second, and feedstock (stearyl vs tallow vs coco) third.
Formulation examples
Textile softener concentrate:
- 15% stearyl amine ethoxylate (5 EO)
- 5% silicone emulsion
- Balance water, preservative
- Apply 0.5–1% in final rinse bath
Antistatic treatment (plastic film):
- 0.5–2% stearyl amine ethoxylate (10 EO) in isopropanol
- Apply by spray or wipe
- Reduces surface resistivity for static control
O/W cream emulsion:
- 4% PEG-40 stearate
- 2% GMS (glycerol monostearate)
- 15% oil phase
- Balance water, preservatives, actives
Cationic asphalt emulsion (illustrative): A CRS-type system uses a low- to mid-EO stearyl or tallow amine ethoxylate as the primary emulsifier, acidified so the amine is protonated, with bitumen dispersed hot. Aggregate adhesion depends on residual cationic charge. Do not substitute a PEG stearate into this recipe — the ester has no cationic drive to the stone.
Quality and specifications
Key specifications for amine ethoxylates include amine value, EO content, cloud point, and pH. For PEG stearates: saponification value, acid value, HLB, and melting point. Venus provides COA with every batch.
| Family | COA parameters | What a shift indicates |
|---|---|---|
| Stearyl amine ethoxylate | Amine value, hydroxyl value, colour, pH, EO moles | Low amine value can mean over-ethoxylation or feedstock mix |
| PEG stearate | Sap value, acid value, melting point, HLB, colour | High acid value: incomplete esterification or hydrolysis |
Store both families sealed, cool, and dry. High-EO pastes can pick up water and cake. Amine ethoxylates can darken with heat and oxygen; keep headspace reasonable and avoid prolonged high-temperature storage. For personal care, assess nitrosamine risk if the formula could see nitrosating conditions — industrial and textile uses dominate amine ethoxylate volumes.
Troubleshooting
Softener bath precipitates: anionic residue from the dyehouse. Rinse fabric; do not dose low-EO amine into a soapy jet. Weak antistat on film: EO too high (not enough surface affinity) or coat weight too low. Asphalt emulsion too stable: EO too high or insufficient acidification. Cream splits on storage: PEG stearate HLB mismatch or low GMS; check oil-phase required HLB rather than raising emulsifier indefinitely. Shampoo too thin: PEG-100 stearate needs the right anionic and salt curve — it is a mild thickener, not a replacement for a full rheology system.
Sourcing from Venus
Venus Ethoxyethers manufactures stearyl amine ethoxylates, tallow amine ethoxylates, and PEG stearate esters at Goa facilities. We support textile, personal care, road construction, and industrial customers globally. Custom EO levels, 30+ years of alkoxylation experience, 1,600+ products, and 90,000 MT group capacity with U.S. manufacturing support export programs. Related pages: HLB scale guide, nonionic surfactants.
Contact Venus Ethoxyethers for amine ethoxylate and PEG stearate samples, TDS, and formulation support.
