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Jun 24, 2016
One of the main purposes of thepolyether-modified silicone oil, as a surfactant for polyurethane foamstabilizer, and as foam stabilizers. In the formation of foamed polyurethanefoam formulations, although its addition amount is limited, but it is a veryimportant ingredient. Polyether modified silicone oil in the production processof polyurethane foam during four.
From a combination of co-emulsificationwhen mixing feed
The main raw material compatibilitypolyether polyol and isocyanate bad. Polyether-modified silicone oil of ahydrophobic group and an isocyanate-soluble, hydrophilic group and polyetherpolyols soluble, can play to help two ingredients are mixed, the role ofemulsification. The reaction can be started at the same time while in the wholesystem.
The bubble-prone and homogenization
The reaction system of surface tensionreduction, the air can be uniformly dispersed fine bubbles form small bubblesin the system kernel. Gaseous carbon dioxide and blowing agent system reactionoccurs resulting easy access to nucleate the formation of bubbles. And then tolower the surface tension there is conducive to the growth of the bubble.
Bubbles stabilized
Before viscosity of the system has not yetreached a certain level, the bubble nucleation film is formed very thin. Sincethe drain, and, and, mechanical shock cause cell wall rupture. Then polyethermodified silicone oil can soak nuclear complex is stabilized by theGibbs-Marangoni effect. Can effectively reduce the cell wall leakage, preventthe occurrence of coalescence of bubbles. In addition, non-ionicpolyether-modified silicone oil can also reduce the air - van der Waals forcestwo-liquid interface of the membrane surface, also contributes to stabilize airbubbles.
Communication of the bubbles
The final stage of flexible polyurethanefoam is formed of foam core communication. Before the completion of theexpansion of nuclear bubble, bubble nuclei in the reaction system is a closedpolyhedron. The nuclear polyhedral bubbles again before polymerization to forma gel of the moment, due to the temperature rise inside the bubble nucleationpressure, there may be a bubble rupture nuclear wall openings. Polyether-modifiedsilicone oil is the role of the system in the low viscosity of the stage thatthe wall membrane stabilizing and that the wall thickness of the film-formingcritical to opening, creating the conditions for the final hole.