Oximino Silanes

SiSiB has been developing and producing oximine silane crosslinkers for the sealant industry for over 30 years, supplying world markets with a successful range of innovative products.

Oxime silane based crosslinkers are used for producing neutral moisture-curing silicone sealants. Using these silane compounds, hydroxy-functionalized silicone polymers are crosslinked to obtain a silicone elastomer under the effect of a catalyst and moisture. When using oximino crosslinkers, no acetic acid or amine is released in contrast to acid or alkaline crosslinking systems, but 2-butanone oxime. As this cleavage product reacts neutrally, sealing compounds based on oximino crosslinkers can be used even on sensitive substrates such as marble.

The various crosslinker differ by their reactivity, with the general rule being: SiSiB® PC7400 TOS > SiSiB® PC7500 VOS > SiSiB® PC7130 MOS.

Mixing different crosslinker types enables setting the rate of a formulation precisely, i.e. skin-over time, curing rate and time to first elastic recovery. Oximino silane crosslinker blends with different ratio are available upon request.

Because of coming MEKO ban in EU, SiSiB, a reliable silicone supplier, developed low MEKO or no MEKO crosslinkers, they are acetoxime & methyl isobutyl ketoxime (MIBKO) and 2-pentanoneoxime (MPKO) based crosslinkers. Those silanes include: SiSiB® PC7133 Methyl MIBKO Silane, SiSiB® PC7530 Vinyltris(methylisobutylketoximino)silane, SiSiB® PC7410 Tetra(methylisobutylketoximino)silane, SiSiB® PC7131 Methyltris(acetoximino), SiSiB® PC7531 Vinyltris(acetoximino)silane, SiSiB® PC7160 Methyltris(2-pentanoneoxime)silane, SiSiB® PC7560 Vinyltris(2-pentanoneoxime)silane.

A simplified cure mechanism for a one-component silicone RTV sealant is show below:

MIBKO and MPKO (Methyl Propyl Ketoxime) can be used as high-efficiency anti-skinning agents for air-drying paints, inks and coatings.