3-Isocyanate-propyltrimethoxysilane (CAS: 15396-00-6) Introduction and Application I

3-Isocyanate-propyltrimethoxysilane (CAS: 15396-00-6) Introduction and Application I

I. Basic Information and Core Characteristics

3-Isocyanate-propyltrimethoxysilane, also known as γ-isocyanate-propyltrimethoxysilane or (3-isocyanate-propyl)trimethoxysilane, has the English name 3-Isocyanatopropyltrimethoxysilane or 3-(Trimethoxysilyl)propyl isocyanate. Its molecular formula is C₇H₁₅NO₄Si, molecular weight is 205.28, and EINECS number 239-415-9. This substance is usually a colorless to pale yellow transparent liquid, possessing dual active groups of isocyanate (-N=C=O) and trimethoxysilyl (-Si(OCH₃)₃), making it a high-performance silane coupling agent. Its core characteristics include: rapid hydrolysis to generate silanol groups under atmospheric humidity; efficient reaction of isocyanate groups with compounds containing active hydrogen (such as alcohols, amines, and water); ability to build stable chemical bonds between organic polymers and inorganic substrates, significantly improving interfacial adhesion strength; and excellent thermal stability, chemical stability, and UV resistance.

II. Synthesis and Storage Considerations This silane is generally prepared by reacting γ-aminopropyltrimethoxysilane with phosgene, or by direct addition synthesis of isocyanate and siloxane. In industrial production, strict control of reaction temperature and pressure is required to ensure product purity of over 97%. During storage, it should be sealed and placed in a cool, dry, and well-ventilated place, avoiding contact with water, alcohols, amines, and other active hydrogen compounds. Keep away from fire and oxidants to prevent polymerization or hydrolytic cross-linking. The shelf life is typically 6 months to 1 year.

III. Core Application Areas

(I) Synthesis of Silane-Terminated Polymers (MS/SPUR)

As a resin terminator and polymer modifier, it is widely used in the preparation of silane-terminated polyethers (MS polymers) and silane-modified polyurethanes (SPUR polymers). By terminating diols or polyether polyols, it imparts a moisture-curing crosslinking mechanism to the polymer, improving the product's adhesive strength, water resistance, weather resistance, and storage stability. It is a core raw material for one-component moisture-curing sealants and adhesives.

(II) Polyurethane Materials

Crosslinking Agent: Used in one-component moisture-curing polyurethane adhesives, sealants, and coatings, it terminates the polyol component, achieving moisture-induced crosslinking and curing, significantly shortening surface drying time and improving coating density and mechanical properties. Adhesion Promoters: Compatible with single-component and two-component reactive polyurethane systems, enhancing the adhesion of polyurethane coatings to inorganic substrates such as glass, metal, ceramics, and concrete, as well as difficult-to-bond plastics such as nylon and ABS. They also improve resistance to damp heat and aging, solving the problem of poor adhesion of traditional polyurethane to special substrates.

Resin Modifiers: Used for modifying hydroxyl resins (such as acrylic resins and PVA), introducing siloxane structures to improve the resin's water resistance, weather resistance, and interfacial adhesion, expanding its application in high-end coatings.