1. Foaming in a polyurethane reaction system by a physical method and a chemical method, and allowing the foam to be uniformly dispersed in the reaction system, wherein the main foaming method utilizes water and isocyanate to produce carbon dioxide to foam.
2. The foam production process requires that the viscosity of the reaction system increase as the foam is stabilized from being escaped.
3. When the foam formation reaches the required number and size, the viscosity of the reaction system needs to be continuously increased or a crosslinking system is formed to stabilize the foam and shape the product.
In this case, we need at least two kinds of catalysts to regulate the progress of the reaction. One kind of catalyst is to promote the reaction of isocyanate and water, that is, to promote the foaming reaction. Normally, the amine catalyst is selected; the other is needed. To promote the reaction of isocyanates with polyethers or alcohols, that is, the growth of polyurethane chains and cross-linking reactions, metal catalysts are generally used. Therefore, in the polyurethane foam synthesis process, we generally use amine catalysts and organometallic catalysts in combination to produce synergistic effects to achieve the best results.