The chemical composition of liquid two-component foaming material is usually composed of component A (isocyanate component) and component B (polyol component). After mixing, the two components react to generate foam. The following is a specific analysis:
1.Component A (isocyanate component)
• Main components: polyisocyanates, the most common are toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI), in addition to polymeric MDI (PAPI).
• Function: As a "crosslinking agent" of the reaction, it reacts with the active hydrogen group in component B and is the core raw material for the formation of foam structure.
2.Component B (polyol component)
Contains a variety of components that participate in the reaction and regulate foam properties:
• Polyols: such as polyether polyol and polyester polyol, which provide hydroxyl (-OH) and react with the-NCO group of isocyanate, forming the basis of foam skeleton.
• Foaming agent: produces gas to expand the mixture and form bubbles. Common ones are physical foaming agents (e.g., Freon substitutes, cyclopentane) and chemical foaming agents (e.g., water, which reacts with isocyanate to produce carbon dioxide).
• Catalyst: Accelerates the reaction, such as amine catalyst (promotes foaming reaction) and organotin catalyst (promotes gel reaction).
• Surfactants: stabilize the foam structure and prevent the foam from bursting. They are usually siloxane compounds.
• Other additives: such as flame retardants, fillers, colorants, etc., which are added according to the application requirements to improve the flame retardant, strength and other properties of the foam.
3.Reaction Principle
When components A and B are mixed, the-NCO groups of isocyanate react with the-OH groups of polyols and water, releasing gas (foaming) to form a porous foam material. The specific ratios and types of components determine the foam's density, hardness, thermal insulation properties, and other characteristics. This versatile material finds extensive applications in insulation systems, packaging solutions, furniture manufacturing, and related industries.