Amine: generally used A33 its role is to promote the reaction of isocyanate and water, adjust the foam density, bubble open rate, etc., mainly to promote the foaming reaction.
Amine: Cracks in foams, holes or blisters in foam
Less amine: The foam shrinks and closes, and the foam is thick at the bottom.
Tin: Tin octoate T-9 is generally used; T-19 is a highly reactive gel reaction catalyst in polyurethane catalysts, mainly to promote the gel reaction, that is, the late reaction.
Tin Multi: Fast gelation, increased viscosity, poor resilience, poor air permeability, resulting in closed cell phenomenon. If the amount is properly increased to obtain a good open-cell foam that is slack, further increasing the amount causes the foam to become denser, resulting in shrinkage, obturation.
Less tin: insufficient gel, cracking caused by foaming process. There is cracking on the edge or top, and there is a phenomenon of stripping and burrs.
Reducing the amine or increasing the tin can increase the strength of the polymer bubble membrane wall when the gas mass occurs, thereby reducing the hollow or cracking phenomenon.
Whether the polyurethane foam has the ideal open or closed cell structure depends mainly on whether the gel reaction rate and the gas expansion velocity are balanced during the foam formation. This balance can be achieved by adjusting the type and amount of tertiary amine catalysts in the formulation as well as foam stabilization and other additives.