Patent ID: 7455799

Claim:
A method of producing polishing pad-use polyurethane foam comprising the steps of: charging a first component, a foaming agent and a second component that reacts with the first component to form polyurethane in specified amounts into a tank and foaming/mixing them for a specified time by a mixer, wherein the mixer comprises a first mixer blade and a second mixer blade having shaft centers in a vertical direction, and the first and second mixer blades are allowed to rotate in reversed directions in a manner so as to engage each other, and are also designed so that the two blades do not interfere with each other so as to allow a gas to be involved in the solution through rotations of the mixer, wherein the number of revolutions in each of the mixer blades is set in a range from 500 to 3000 rpm, and after the above-mentioned step, pouring the mixed solution into a mold so as to react with one another to be cured, wherein the mixed solution is poured into the mold through a valve attached to a bottom of the tank said mold being disposed underneath the tank, wherein said polyurethane foam has an average cell diameter in a range from 10 to 70 μm with the number of cells in a range from 100 to 700/mm 2 .