Methyltriacetoxysilane

CAS: 4253-34-3

Overview

Methyltriacetoxysilane ( CAS 4253-34-3 ), commonly abbreviated as MTAS, is an acetoxy-functional silane used as a crosslinker and curing agent across adhesive, sealant, and coating systems.

It releases acetic acid upon moisture exposure, triggering condensation cure in silicone-based formulations. MTAS is a primary crosslinker in one-component acetoxy-cure silicone sealants.

This includes construction, glazing, and sanitary grades where fast surface cure and strong substrate adhesion are required. In industrial coatings, it functions as a surface modifier to improve adhesion.

It is effective for glass, metals, and mineral substrates. Silicone elastomer compounders use it to control network density and mechanical properties in RTV systems for various industrial applications.

Personal care formulators apply it in film-forming and conditioning systems where silicone crosslinking at ambient conditions is needed without heat activation or specialized equipment.

Methyltriacetoxysilane is supplied as a clear liquid, typically in drum and IBC quantities for industrial buyers. Technical grade is the standard commercial form for most manufacturing needs.

Purity specifications are commonly at 97% or higher to ensure consistent performance. Packaging options generally range from small containers for laboratory use up to bulk quantities for manufacturers.

Physical Properties

Melting Point	40.5 °C
Boiling Point	87-88 °C @ Press: 3 Torr
Density	1.175 g/cm³
Flash Point	185 °F
Appearance	Colorless or yellowish transparent liquid
Color	White or Colorless to Almost white or Almost colorless
Odor	Acrid odor
Form	solid
Water Solubility	1000g/L at 20℃
Vapor Pressure	0.053-26Pa at 20-25℃
Refractive Index	1.52-1.522
Log P	-2.4 at 20℃

Safety & Handling

Danger GHS05 GHS07 GHS08 Hazard Statements H302 Harmful if swallowed H314 Causes severe skin burns and eye damage H315 Causes skin irritation H318 Causes serious eye damage H319 Causes serious eye irritation H335 May cause respiratory irritation H371 May cause damage to organs Precautionary Statements P260 Do not breathe dust/fume/gas/mist/vapours/spray. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P280 Wear protective gloves/protective clothing/eye protection/face protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P319 Get medical advice/attention if you feel unwell. P321 Specific treatment (see … on this label). P330 Rinse mouth. P363 Wash contaminated clothing before reuse. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P308+P316 Get emergency medical help immediately. P332+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P362+P364 Take off contaminated clothing and wash it before reuse. P403+P233 Store in a well-ventilated place. Keep container tightly closed. P301+P330+P331 Rinse mouth. Do NOT induce vomiting. P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P305+P354+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code	29319090
UN Number	1759
WGK (Germany)	2

Other Names

Industries

Personal Care & Cosmetics Coatings, Adhesives, Sealants & Elastomers Plastics & Polymers