REAXIS® C227 (Dibutyltin bis-(1-thioglycerol)), also known as Dibutyl bis-(2,3-Dihydroxypropyl Mercaptan), is butyl-based dialkyl organotin with added functionality. REAXIS® C227 has the characteristic reactivity of a Sn (IV) organotin catalyst with improved upfront delay and improved hydrolytic stability due to the presence of a ligand with thiol functionality. Used primarily in polyurethanes, REAXIS® C227 imparts more controlled reactivity versus standard metal carboxylates such as REAXIS® C218 (Dibutyltin Dilaurate), REAXIS® C216 (Dioctyltin Dilaurate), and REAXIS® C325 (Dimethyltin Dineodecanoate). Catalysts similar to REAXIS® C227 include, REAXIS® C319 (Dibutyltin Mercaptide), REAXIS® C320 (Dioctyltin Mercaptide), REAXIS® C214 (Dioctyltin bis-(isooctyl Mercaptoacetate) and its isomer, REAXIS® C416 (Dioctyltin bis-(2-Ethylhexyl Mercaptocetate)).
|Tin Content (%)||25.5 - 27.5|
|Density (g/ml)||1.35 - 1.40|
|Color (Gardner Number)||5 Max|
Unlike standard organotin carboxylates, sulfur-bearing organotins are primarily used as a catalyst for polyurethanes. Catalysts such as REAXIS® C227 tend to be inactive in silicone and esterification-related applications. As the sulfur ligand acts as a blocking agent, thermal deblocking is required to initiate the back-end cure. Thus, catalysts such as REAXIS® C227 tend to perform best in adhesive, elastomer, and foam applications with adequate exotherms. For coating applications, REAXIS® C227 can be used in baked cured systems in contrast to ambient cured systems.
As is typical of most organotin and inorganic tin catalysts, the specific ligand contributes a major influence on overall reactivity. This is specifically highlighted regarding sulfur-bearing ligands. In general, these sulfur ligands impart improved front-end delay and hydrolytic stability versus standard tin carboxylates. Standard ligands include thiols, as is the case here with thioglycerol, mercaptides and mercaptoacetates. Reactivity as defined by delay, thermal availability, hydrolytic stability, and final cure will depend on the specific ligand, tin content, alkyl group and, most importantly, other raw materials used in the specific polyurethane formulation. In regard to the reactivity of the various urethane reactions, catalysts such as REAXIS® C227 will selectively catalyze the isocyanate-polyol reaction, with less of an effect on the water reaction. Given its synthetic nature, REAXIS® C227 imparts minimal color at higher temperatures.
REAXIS® C227 should be stored in the original packaging at moderate temperatures and kept from freezing. The container should be closed tightly after each use to maximize shelf life. Characteristic of most Sn (IV) organotins, the primary cause of instability would be hydrolysis. Although more stable compared to organotin carboxylates, long-term contact with moisture could result in hydrolysis with the formation of tin oxide insolubles leading to deactivation of REAXIS® C227.