Froth and method of producing froth
AssigneePraxair S.T. Technology, Inc.
InventorsBrian Lombardo, Jeffrey P. Otto
Life of this patent
Estimating the term…
Abstract
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.
Claims45
A method of producing a stable resin froth used to produce a microcellular pad or belt comprising the steps of placing a thermosetable liquid polymer or prepolymer resin and nucleation surfactant in at least one tank, metering a frothing agent into said tank by way of at least one tube or sparge, drawing off said frothing agent from the headspace of said tank so as to reach a steady state of continuous flow of the frothing agent from said tube or sparge to said headspace of said tank, and agitating said thermosetable liquid polymer or prepolymer resin, nucleation surfactant and frothing agent through the use of an impeller at a controlled temperature and pressure.
A method of producing a high density, microcellular pad or belt comprising the steps of placing a thermosetable liquid polymer or prepolymer resin and nucleation surfactant in at least one tank, agitating said thermosetable liquid polymer or prepolymer resin and nucleation surfactant throught the use of at least one impeller, metering a frothing agent into said tank by way of a tube or sparge located below said impeller, drawing off said frothing agent from the headspace of said tank so as to reach a steady state of continuous flow of the frothing agent from below said impeller to said headspace of said tank, metering the resin froth under pressure to a mix head, combining the resin froth with a curative, and injecting or pouring the resin froth into a mold;
- said pad or belt being free of hollow microelements or microballoons.
A method for making high density foam with controlled, reproducible microcellular structure by mechanical frothing, comprising agitating a liquid polymer resin in the presence of a frothing agent and nucleation surfactant at a controlled temperature and any absolute pressure in order to produce a stable froth, metering the resin froth under pressure to a mixhead, optionally combining the resin froth with a curative for the resin, and injecting or pouring the resin froth into a mold.
A froth for producing microcellular pads and belts with consistent cell structures or properties, comprising a polymer or thermosettable polymer, a nucleation surfactant, and a frothing agent, wherein said froth is free of hollow polymeric microelements or micro ballons.
A high density microcellular pad or belt with consistent cell structures, comprising a polymer or thermosettable polymer, a nucleation surfactant, and a frothing agent, wherein said froth is free of hollow polymeric microelements or microballoons.
Dependencies are inferred from the claim text.