US Patent 7718102 Froth and method of producing froth

Foam for making pads and belts with controlled, reproducible microcellular structure and method of making such foam in a fast and efficient manner. Under constant pressure and temperature, a prepolymer is mixed with the nucleation surfactant in a tank in the presence of a frothing agent metered into the tank by way of a dip tube or sparge. The nitrogen gas is sheared into small bubbles and is drawn off from the headspace of the tank creating a continuous flow of nitrogen. The pressure of the tank may vary from any absolute pressure down to near complete vacuum, thereby all but eliminating the pressure requirement. The froth of the present invention has a more consistent cell structure and increased cell count.