Control of Cell Openings in Flexible Urethane Foam
High density urethane foam (10~20lb/ft3) is used for carpet lining, while low density foam is used for furniture (such as foam pad), transportation (such as car seat, etc.) and packaging.
Many physical properties of soft urethane foam and the mechanical response of cushioning materials are greatly affected by its airflow, and the influence of additives and siloxane surfactants on reaction is also great.
In fact, airflow is difficult to control because the role of siloxane surfactants has not been fully cleaned in the process of cell opening. The bubbles formed by carbon dioxide in urethane are unstable unless siloxane surfactants are used. It has been shown that siloxane surfactants have a great influence on the cell structure such as cell size and air permeability. Typical surfactants are copolymers containing siloxane main chain and poly (ethylene oxide-co-propylene oxide) grafts.
The amount of surfactant, the length of main chain, the frequency and composition of grafting vary with the formulation of polyurethane. Surfactants must stabilize carbon dioxide bubbles; however, in flexible urethane foam, the "window" between bubbles must be broken in the polymerization process to prevent shrinkage. Additives that affect the reaction kinetics also play an important role in the opening of the cell. Because urea separation and bulk liquid stretching dilute are the triggering force of open cell holes, it controls the foaming reaction and gel reaction, and obtaining the equilibrium between the bulk viscosity and the rheological curve of urea phase separation is a very effective way to control the degree of cell opening.
Yantai Tengda Polyurethane Co., Ltd. sells soft urethane foam and high density urethane foam all the year round. Welcome to order and purchase!