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Surface tension is lower than that conducive to bubble growth

Jun 8, 2018

Polyurethane foam stabilizer

One of the main purposes of the polyether-modified silicone oil, as a surfactant for polyurethane foam stabilizer, and as foam stabilizers. In the formation of foamed polyurethane foam formulations, although its addition amount is limited, but it is a very important ingredient. Polyether modified silicone oil in the production process of polyurethane foam during four.

From a combination of co-emulsification when mixing feed

The main raw material compatibility polyether polyol and isocyanate bad. Polyether-modified silicone oil of a hydrophobic group and an isocyanate-soluble, hydrophilic group and polyether polyols soluble, can play to help two ingredients are mixed, the role of emulsification. The reaction can be started at the same time while in the whole system.

The bubble-prone and homogenization

The reaction system of surface tension reduction, the air can be uniformly dispersed fine bubbles form small bubbles in the system kernel. Gaseous carbon dioxide and blowing agent system reaction occurs resulting easy access to nucleate the formation of bubbles. And then to lower the surface tension there is conducive to the growth of the bubble.

Bubbles stabilized

Before viscosity of the system has not yet reached a certain level, the bubble nucleation film is formed very thin. Since the drain, and, and, mechanical shock cause cell wall rupture. Then polyether modified silicone oil can soak nuclear complex is stabilized by the Gibbs-Marangoni effect. Can effectively reduce the cell wall leakage, prevent the occurrence of coalescence of bubbles. In addition, non-ionic polyether-modified silicone oil can also reduce the air - van der Waals forces two-liquid interface of the membrane surface, also contributes to stabilize air bubbles.

Communication of the bubbles

The final stage of flexible polyurethane foam is formed of foam core communication. Before the completion of the expansion of nuclear bubble, bubble nuclei in the reaction system is a closed polyhedron. The nuclear polyhedral bubbles again before polymerization to form a gel of the moment, due to the temperature rise inside the bubble nucleation pressure, there may be a bubble rupture nuclear wall openings. Polyether-modified silicone oil is the role of the system in the low viscosity of the stage that the wall membrane stabilizing and that the wall thickness of the film-forming critical to opening, creating the conditions for the final hole.