Optimized emulsion drying process for making micronized polyetherimide polymers

Abstract

A process for making ultra-fine particles of a high performance polymer in a yield greater than 90%, which includes dissolving the high performance polymer in an organic solvent capable of dissolving the polymer to form a solution; emulsifying the solution by combining the solution with water and a surfactant to form an emulsion; transferring the emulsion into a receiving water containing a surfactant to remove the organic solvent and form a slurry; and recovering particles of less than 75 microns in diameter in a yield greater than 90%.

1 .- 34 . (canceled) 
     
     
         35 . Ultra-fine particles of a high performance polymer in a yield greater than 90%, produced by the process comprising:
 a. dissolving the high performance polymer in an organic solvent capable of dissolving the polymer to form a solution;   b. emulsifying the solution by combining the solution with water and a surfactant to form an emulsion;   c. transferring the emulsion into a receiving water containing a surfactant to remove the organic solvent and form a slurry; and,   d. recovering particles of <75-micron diameter in a yield greater than 90%.   
     
     
         36 . The ultra-fine particles according to  claim 35 , produced by the process further comprising filtering the slurry to form a wet cake. 
     
     
         37 . The ultra-fine particles according to  claim 35 , produced by the process further comprising at least one of washing or re-slurrying the wet cake with de-ionized water. 
     
     
         38 . The ultra-fine particles of  claim 35 , wherein the high performance polymer comprises polyetherimide and the polyetherimide particles have a particle size of less than 75 microns. 
     
     
         39 . The ultra-fine particles of  claim 38 , wherein the polyetherimide comprises (a) a polyetherimide resin, and (b) a phosphorus-containing stabilizer, in an amount that is effective to increase the melt stability of the polyetherimide resin, wherein the phosphorus-containing stabilizer exhibits a low volatility such that, as measured by thermogravimetric analysis of an initial amount of a sample of the phosphorus-containing stabilizer, greater than or equal to 10 percent by weight of the initial, amount of the sample remains unevaporated upon heating of the sample from room temperature to 300° C. at a heating rate of a 20° C. per minute under an inert atmosphere. 
     
     
         40 . The ultra-fine particles of  claim 39 , wherein the phosphorous-containing stabilizer has a formula P—R′ a  where R′ is independently H, alkyl, alkoxy, aryl, aryloxy, or oxy substituent and a is 3 or 4. 
     
     
         41 . Ultra-fine particles of polyetherimide, wherein the polyetherimide comprises (a) a polyetherimide resin, and (b) a phosphorus-containing stabilizer, in an amount that is effective to increase the melt stability of the polyetherimide resin, wherein the phosphorus-containing stabilizer exhibits a low volatility such that, as measured by thermogravimetric analysis of an initial amount of a sample of the phosphorus-containing stabilizer, greater than or equal to 10 percent by weight of the initial amount of the sample remains unevaporated upon heating of the sample from room temperature to 300° C. at a heating rate of a 20° C. per minute under an inert atmosphere; and the polyetherimide particles have a particle size of less than 75 microns. 
     
     
         42 . The ultra-fine particles of  claim 41 , wherein the phosphorous-containing stabilizer has a formula P—R′ a , where R′ is independently H, alkyl, alkoxy, aryl, aryloxy, or oxy substituent and a is 3 or 4.