Polishing pad and method of making same

Abstract

An article or polishing pad for altering a surface of a work piece includes a polymer matrix created by reaction injection molding of size controlled gas bubbles within a polyurethane matrix. The proposed liquid urethane precursor is first injected into an actuated mold and cured. The molded product is then removed from the mold and double side faced or ground to form a single thin polishing pad comprising a single layer of homogeneous material.

1 . A nonporous polishing pad of uniform microcellular size produced by introducing a gas into a polymeric resin contained in a pressurized tank, pumping the polymeric resin and gas mixture through a fine porosity stone mixer, mixing the polymeric resin and gas mixture with an isocyanate to form a resulting mixture, and injecting the resulting mixture into a mold.  
   
   
       2 . The polishing pad of  claim 1  wherein the polymeric resin and gas mixture are pumped through an emulsifier after being pumped through the fine porosity stone mixer.  
   
   
       3 . The polishing pad of  claim 1  wherein the polymeric resin and gas mixture are passed through a homogenizing mixer after being pumped through the fine porosity stone mixer.  
   
   
       4 . The polishing pad of  claim 1  wherein the gas is introduced into the polymeric resin through a sparging tube contained within the pressurized tank.  
   
   
       5 . The polishing pad of  claim 4  wherein the polymeric resin and gas mixture are pumped through an emulsifier after being pumped through the fine porosity stone mixer.  
   
   
       6 . The polishing pad of  claim 4  wherein the polymeric resin and gas mixture are passed through a homogenizing mixer after being pumped through the fine porosity stone mixer.  
   
   
       7 . The polishing pad of  claim 1  wherein the polymeric resin and gas mixture are recirculated through the pressurized tank, containing a mixer, and the fine porosity stone mixer prior to mixing the polymeric resin and gas mixture with the isocyanate.  
   
   
       8 . The polishing pad of  claim 1  wherein the uniform microcellular structure comprises a closed cell membrane having an average cell diameter within a range of about 0.05 to 100 micrometers.  
   
   
       9 . The polishing pad of  claim 8  wherein the average cell diameter comprises a range of about 0.05 to 30 micrometers.  
   
   
       10 . The polishing pad of  claim 1  wherein a surface material of the pad has a low coefficient of friction.  
   
   
       11 . The polishing pad of  claim 1  wherein the polymeric matrix formed from the resulting mixture comprises at least one of a polyurethane, a polyester, a polysulfone, and a polyvinyl acetate.  
   
   
       12 . The polishing pad of  claim 1  wherein said polymeric resin includes glycol as a catalyst.  
   
   
       13 . The polishing pad of  claim 1  wherein said polymeric resin comprises at least one of a polyurethane, a polyglycol, a polyether polyol, a polymer polyol, an aliphatic polyester polyol, an aromatic polyester polyol, a PTMEG, a PTHF, a castor oil based polyol, a polycaprolactone polyol, a hydroxyl terminated polybutadiene, an acrylic polyol, and a polyamine.  
   
   
       14 . The polishing pad of  claim 1  further comprising a porous transparent portion or porous translucent portion that is added to the pad subsequent to molding the pad.  
   
   
       15 . The polishing pad of  claim 1  further comprising grooves formed in a surface of the pad.  
   
   
       16 . The polishing pad of  claim 1  wherein the gas comprises at least one of an inert gas, a reactive gas, and a reductive gas.  
   
   
       17 . The polishing pad of  claim 16  wherein the gas comprises at least one of a dry air, an argon gas, a dry nitrogen gas, and a dry oxygen gas.  
   
   
       18 . The polishing pad of  claim 1  further comprising at least one of a surfactant and an ultraviolet stabilizer.  
   
   
       19 . A nonporous polishing pad of uniform microcellular size produced by introducing a gas into a polymeric resin through a recirculating pump which pumps the polymeric resin and gas mixture through a fine porosity stone mixer, mixing the polymeric resin and gas mixture with an isocyanate to form a resulting mixture, and injecting the resulting mixture into a mold.  
   
   
       20 . The polishing pad of  claim 19  wherein the polymeric resin and gas mixture are pumped through an emulsifier after being pumped through the fine porosity stone mixer.  
   
   
       21 . The polishing pad of  claim 19  wherein the polymeric resin and gas mixture are passed through a homogenizing mixer after being pumped through the fine porosity stone mixer.  
   
   
       22 . The polishing pad of  claim 19  wherein the polymeric resin and gas mixture are recirculated through a pressurized tank having a mixer and the fine porosity stone mixer prior to mixing the polymeric resin and gas mixture with the isocyanate.  
   
   
       23 . The polishing pad of  claim 19  wherein the uniform microcellular structure comprises a closed cell membrane having an average cell diameter within a range of about 0.05 to 100 micrometers.  
   
   
       24 . The polishing pad of  claim 23  wherein the average cell diameter comprises a range of about 0.05 to 30 micrometers.  
   
   
       25 . The polishing pad of  claim 19  wherein a surface material of the pad has a low coefficient of friction.  
   
   
       26 . The polishing pad of  claim 19  wherein the polymeric matrix formed from the resulting mixture comprises at least one of a polyurethane, a polyester, a polysulfone, and a polyvinyl acetate.  
   
   
       27 . The polishing pad of  claim 19  wherein said polymeric resin includes glycol as a catalyst.  
   
   
       28 . The polishing pad of  claim 19  wherein said polymeric resin comprises at least one of a polyurethane, a polyglycol, a polyether polyol, a polymer polyol, an aliphatic polyester polyol, an aromatic polyester polyol, a PTMEG, a PTHF, a castor oil based polyol, a polycaprolactone polyol, a hydroxyl terminated polybutadiene, an acrylic polyol, and a polyamine.  
   
   
       29 . The polishing pad of  claim 19  further comprising a porous transparent portion or a porous translucent portion that is added to the pad subsequent to molding the pad.  
   
   
       30 . The polishing pad of  claim 19  further comprising grooves formed in a surface of the pad.  
   
   
       31 . The polishing pad of  claim 19  wherein the gas comprises at least one of an inert gas, a reactive gas, and a reductive gas.  
   
   
       32 . The polishing pad of  claim 31  wherein the gas comprises at least one of a dry air, an argon gas, a dry nitrogen gas, and a dry oxygen gas.  
   
   
       33 . The polishing pad of  claim 19  further comprising at least one of a surfactant and an ultraviolet stabilizer.  
   
   
       34 . The polishing pad of  claim 1  wherein the polymeric resin and gas mixture are directed through a high shear cavitation device prior to adding the isocyanate.  
   
   
       35 . The polishing pad of  claim 19  wherein the polymeric resin and gas mixture are directed through a high shear cavitation device prior to adding the isocyanate.  
   
   
       36 . The polishing pad of  claim 1  further comprising hardware incorporated into the polishing pad during the molding process, or after the molding process by machining away a portion of the pad.  
   
   
       37 . The polishing pad of  claim 19  further comprising hardware incorporated into the polishing pad during the molding process, or after the molding process by machining away a portion of the pad.