Today we introduce several common metal catalysts for polyurethane, which are dibutyltin dilaurate, stannous isooctanoate, and the best catalysts.
Dibutyltin dilaurate is referred to as T12, which was introduced earlier by American Air. The catalyst has suitable viscosity, and it has a lot of catalytic effect not only on gel catalysis but also on foaming, with strong metallic properties, and the relevant data are as follows
It is used in polyurethane CASE and foaming materials, and is one of the more common varieties, the solvent or additives used by different manufacturers vary, its main content is basically dibutyltin laurate, the system does not match the subsequent easy precipitation of the catalyst, the surface may appear white powder.
Another common type of tin metal catalyst is stannous isooctanoate, T9 for short, which is slightly more viscous than T12. It is more efficient than T12 because of the stannous nature and the relatively short carbon chain of the organic acid, and is a yellow liquid in color. Due to its inherent high viscosity, this also means that it requires more dilution than T12 to meet downstream usage habits. The relevant data are as follows.
Generally speaking, metal-based catalysts are mainly used for gelation reactions, while tertiary amines are used for foaming reactions, both of which are alkaline and therefore can promote the addition polymerization of polyurethane, while some friends slow down the foam rise time or increase the operating time to reduce the reaction speed of polyurethane by adding acid to certain raw materials. The latter reduces the polymerization speed by increasing the polarity of the system, i.e., by increasing the competition with NCO. As for metals, they are more likely to form ligands with NCO first due to the high energy of their molecular orbitals or to lose electrons more easily, thus promoting the transfer of hydroxyl hydrogen protons, while tertiary amines are more likely to make the reaction proceed in the direction of aromatic amine structures due to their structural similarity, which in turn rearrange to form carbon dioxide and generate foam.
