Behentrimonium Methosulfate (BTMS-50 / BTMS-25) CAS 81646-13-1

Introduction to Behentrimonium Methosulfate

Behentrimonium Methosulfate (BTMS) is a highly efficient, quaternary ammonium cationic surfactant and emulsifier. Despite the word “sulfate” in its name, the methosulfate counterion is exceptionally mild, non-irritating, and completely distinct from harsh cleansing sulfates like Sodium Lauryl Sulfate (SLS). Commercially, it is most widely traded as “BTMS-50” (containing approximately 50% active behentrimonium methosulfate and 50% cetearyl alcohol as a carrier and co-emulsifier) or “BTMS-25”.

Derived naturally from rapeseed (colza) oil, BTMS possesses a strong affinity for keratin and skin proteins due to its positive charge, providing unparalleled slip, detangling, and anti-static effects. It is the gold standard in “sulfate-free” and premium salon cosmetic formulations. The critical processing parameter is its melting point: it must be heated to 60–75 °C (140–167 °F) in the oil phase to melt completely before emulsification with the heated aqueous phase.

Key Features of Behentrimonium Methosulfate

• Superior detangling and slip. The C22 (behenyl) alkyl chain provides exceptional wet and dry combability, drastically reducing hair breakage and static flyaway without heavy buildup or greasiness.
• Mild, non-irritating chemistry. The methosulfate counterion is gentle on the scalp and eyes, making it suitable for baby care, sensitive skin lotions, and sulfate-free premium formulations.
• Powerful oil-in-water emulsifier. Capable of emulsifying high oil phases (up to 25-30%) to create stable, thick, and luxurious creams without the need for secondary synthetic emulsifiers like polysorbates.
• Plant-derived and eco-friendly. Sourced from renewable rapeseed oil, readily biodegradable, and highly favored in vegan, natural, and “clean beauty” product lines.
• Excellent substantivity. The cationic charge ensures the active ingredient adsorbs directly onto damaged, negatively charged hair cuticles and skin, providing long-lasting conditioning that resists immediate rinse-off.

Behentrimonium Methosulfate Chemical & Physical Properties

Applications of Behentrimonium Methosulfate

Rinse-off hair conditioners and masks: Melt 2–8% BTMS-50 in the oil phase at 70 °C (158 °F), then emulsify with the heated water phase using high-shear mixing. Provides immediate detangling, slip, and softness for damaged, curly, or chemically treated hair. Compatible with cationic polymers like Polyquaternium-10.

Leave-in conditioners and detangling sprays: Used at lower concentrations (1–3%) to create lightweight, non-greasy lotions that eliminate static flyaway and improve wet-combing. Forms stable, low-viscosity emulsions suitable for spray bottles.

Skin care lotions and body butters: Acts as a primary emulsifier and skin-conditioning agent at 2–5%. Delivers a powdery, non-tacky, and velvety after-feel on the skin, making it ideal for premium body butters, shaving creams, and men’s grooming balms.

Baby care and sensitive formulations: Due to its extreme mildness and lack of ethoxylation, it is the preferred cationic emulsifier for baby wipes, diaper creams, and tear-free conditioning detanglers.

Storage & Safety Precautions for Behentrimonium Methosulfate

• Storage: Store in original PE bags or fiber drums in a cool, dry warehouse below 35 °C (95 °F). Protect from moisture and direct sunlight. Although stable, prolonged exposure to high heat may cause the pastilles to fuse or cake together. Keep away from strong anionic surfactants in raw material storage to prevent cross-contamination.
• Safety: Concentrated BTMS pastilles may cause severe eye irritation and mild skin irritation. Wear safety goggles, nitrile gloves, and a dust mask when handling bulk quantities or melting the product. In case of eye contact, flush immediately with water for 15 minutes and seek medical advice.
• Transport: Behentrimonium Methosulfate is Non-DG under IATA/IMDG/ADR. No UN number, no packing group. Standard dry cargo transport is acceptable. Avoid leaving shipping containers in direct sunlight where internal temperatures could exceed the 65 °C (149 °F) melting point, causing product fusion.
• QC note: Verify active content and drop point upon receipt. Melt a sample to ensure a clear, homogeneous oil phase without undissolved granules. Test a 2% emulsion in distilled water to confirm stability, pH (5.0–7.0), and characteristic cationic slip.

Behentrimonium Methosulfate FAQ

Q: Is Behentrimonium Methosulfate a harsh sulfate like SLS or SLES?

A: No. Despite the name, the “methosulfate” is simply a counterion used to stabilize the cationic behentrimonium molecule. It is non-irritating, non-cleansing, and completely safe for sulfate-free, color-treated, and keratin-treated hair regimens.

Q: What is the difference between BTMS-50 and BTMS-25?

A: BTMS-50 contains approximately 50% active behentrimonium methosulfate and 50% cetearyl alcohol. BTMS-25 contains roughly 25% active ingredient and 75% cetearyl alcohol (or similar fatty alcohols). BTMS-50 provides stronger conditioning and emulsification power per gram, while BTMS-25 is more cost-effective for lighter formulations.

Q: Can BTMS be mixed with anionic surfactants like SLES in a shampoo?

A: Direct mixing of cationic BTMS with anionic surfactants in the same concentrated formula will cause immediate precipitation and neutralization. However, they can be used sequentially (e.g., an anionic shampoo followed by a cationic BTMS conditioner) or formulated in specialized dual-phase systems.