N-(2-Aminoethyl)-3-aminopropylmethyldimethoxysilane (KH-602)

KH-602 is a difunctional diaminosilane with a unique structure: a diaminopropylethylene backbone attached to a methyldimethoxysilane group. This structure makes KH-602 distinctly different from other aminosilanes. The methyl substituent at silicon (unlike the all-alkoxy amino silanes KH-550 and KH-792) reduces hydrolytic sensitivity and prevents rapid self-condensation, making KH-602 far more stable in formulated sealants and adhesives. The diamine group provides high basicity and strong adhesion promotion, while difunctionality allows KH-602 to function as a chain extender rather than a crosslinker — preserving flexibility in the final cured system.

KH-602 is the industry-standard adhesion promoter for neutral-cure and oxime-cure RTV-1 silicone sealants to glass, aluminum, anodized surfaces, and glazed ceramic tiles. Unlike KH-550 or KH-792 which can promote premature crosslinking if used as-is in sealant formulations, KH-602 incorporates cleanly due to the methyl-substituted, difunctional silane geometry — it does not disrupt the PDMS network structure. Sealant formulations typically use 0.2–0.8 phr KH-602 to pass construction adhesion standards (ISO 8339, ASTM C794) on non-porous substrates without primer.

In polyurethane adhesives and coatings, KH-602 acts as both an adhesion promoter and a latent amine curative. Added to one-component moisture-cure PU systems at 0.5–2%, it migrates to the substrate interface and forms covalent Si-O bonds with glass, metal oxide, and mineral surfaces, dramatically improving adhesion durability under hot-wet aging. In two-component PU systems, KH-602 participates as a slow-reacting secondary amine extender, extending pot life while contributing to final adhesion.

KH-602 is also used as a glass fiber sizing component in nylon (PA) and polypropylene composites where its diamine group provides dual compatibility — amino reactivity with the coupling chemistry and high basicity to activate mineral surfaces.