Polyurethane Foam Catalysts
In regard to polyurethane foam catalysts, two main types are used: tertiary amines and metal-based catalysts. Tertiary amines are commonly referred to “blowing” catalyst as they are selective toward isocyanate/water reaction whereas metal-based catalysts are considered as “gelation” catalysts as they are preferential toward the isocyanate/polyol reaction. Reaxis supplies a wide range of tin-based, bismuth-based, and zinc-based metal catalysts.
The choice of catalysts depends on the specific foam type, raw materials used, desired final properties and, increasingly, environmental drivers. Metal-based catalysts, like tertiary amines are more selective toward specific reactions involved in polyurethane synthesis. Some common Reaxis products used in polyurethane foams include:
Inorganic Tin Polyurethane Foam Catalysts
Inorganic tin products such as REAXIS® C129 (Stannous Octoate) and REAXIS® C125 (Stannous Neodecanoate) are commonly used in the production of flexible foams. The benefits of these tin-based products include high active metal content, good ligand compatibility, long history of commercialization and no organotin content.
Organotin Carboxylate Polyurethane Foam Catalysts
Organotin carboxylate products such as REAXIS® C218 (Dibutyltin Dilaurate), REAXIS® C233 (Dibutyltin Diacetate) and REAXIS® C325 (Dimethyltin Dineodecanoate) are commonly used in both rigid and flexible foams. Primarily used to promote the isocyanate and polyol reactions, these catalysts will also partially catalyze the water and crosslinking reactions.
Organotin-Sulfur Polyurethane Foam Catalysts
Organotin-sulfur products such as REAXIS® C319 (Dibutyltin Dimercaptide), REAXIS® C322 (Dibutyltin bis-(2-ethylhexyl Mercaptoacetate)) and REAXIS® C214 (Dioctyltin bis-(isooctyl Mercaptoacetate)) are commonly used in rigid foam applications where enhanced front-end reaction delay and improved hydrolytic stability, versus organotin carboxylates, is required.
Zinc-Based and Bismuth-Based Polyurethane Foam Catalysts
The use of bismuth and zinc-based metal catalysts is increasing as regulations tighten on organotins. Common products include REAXIS® C716 (Bismuth Neodecanoate), REAXIS® C3210 (Bismuth Neodecanaote) REAXIS® C616 (Zinc Neodecanaote) and the bismuth-zinc metal blend, REAXIS® C708 (Bismuth/Zinc Neodecanoate) and REAXIS® C717, (Bismuth/Zinc Octoate). Our line of non-carboxylate-based bismuths include REAXIS® C739P50 and REAXIS® C739E50 provide for improved isocyanate/polyol selectivity and hydrolytic stability and like tin catalysts, bismuth carboxylates are more selective toward the isocyanate/polyol reaction. The selectivity towards the crosslinking reactions is unique to the zinc carboxylate-based catalysts.