Selective hydroperoxidation of polyolefins in an aqueous slurry

Abstract

Polyolefins are selectively hydroperoxidized in an aqueous slurry with an ozone-oxygen mixture at temperatures between 65° and 100° C for a time which does not exceed one hour to introduce sufficient hydroperoxides for later graft copolymerization while minimizing formations of higher oxidation products of the polymer and limiting molecular weight degradation.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and secure by Letters Patent is: 
     
       1. A process for selective hydroperoxidation of finely divided solid polypropylene particles, which consists essentially of: contacting a cationic surfactant-free, slurry of said polypropylene, having a particle size of about 30 to 1,000 microns in water with a 50 to 90 mg. of ozone per liter of air mixture as the sole free radical initiator, at a temperature within the range of from 75° C. to 95° C.,   and for a time sufficient to obtain a hydroperoxide concentration in said polypropylene between 0.014 and 0.050 weight percent,   whereby formation of higher oxidation products than hydroperoxides is significantly less than said formation at temperatures outside said 75° C. to 95° C. range.   
     
     
       2. A process in accordance with claim 1 wherein said polypropylene has a molecular weight of at least 10,000. 
     
     
       3. A process in accordance with claim 1 wherein the ozone treat rate is from 18 to 225 mg O 3  /lb of polymer/min. 
     
     
       4. A process in accordance with claim 1 wherein the polyolefin is polypropylene powder having a particle size within the range from 100 to 600 microns. 
     
     
       5. A process in accordance with claim 1 wherein the ozone treat rate is from 25 to 55 mg O 3  /lb of polymer/min. 
     
     
       6. A process in accordance with claim 1 wherein the temperature is from 78° to 94° C., the time of oxidation is from 8 minutes, the amount of ozone reacted is about 236 to 271 mg/100 g polymer, and the ROOH concentration in the polymer is about 0.044 to 0.045 wt. %. 
     
     
       7. A process according to claim 1 wherein the time of said contacting is 16 minutes or less. .Iadd. 8. A process for selective hydroperoxidation of finely divided solid polypropylene particles, which consists essentially of: contacting a cationic surfactant-free, slurry of said polypropylene, having a particle size of about 30 to 1000 microns in water with a 50 to 90 mg. of ozone per liter of an ozone-oxygen mixture as the sole free radical initiator, at a temperature within the range of from 75° C. to 95° C.,   and for a time sufficient to obtain a hydroperoxide concentration in said polypropylene between 0.014 and 0.050 weight percent,   whereby formation of higher oxidation products than hydroperoxides is significantly less than said formation at temperatures outside said 75° C. to 95° C. range. .Iaddend..Iadd. 9. A process in accordance with claim 8 wherein said polypropylene has a molecular weight of at least 10,000. .Iaddend..Iadd. 10. A process in accordance with claim 8 wherein the oxygen treat rate is from 18 to 225 mg O 3  /lb of polymer/min. .Iaddend..Iadd. 11. A process in accordance with claim 8 wherein said polypropylene particles have a particle size within the range from 100 to 600 microns. .Iaddend..Iadd. 12. A process in accordance with claim 8 wherein the ozone treat rate is from 25 to 55 mg O 3  /lb of polymer/min. .Iaddend. .Iadd. 13. A process in accordance with claim 8 wherein the temperature is from 78° to 94° C., the time of oxidation is about 8 minutes, the amount of ozone-reacted is about 236 to 271 mg/100 g polymer, and the ROOH concentration in the polymer is about 0.044 to 0.045 wt. %. .Iaddend..Iadd. 14. A process according to claim 8 wherein the time of said contacting is 16 minutes or less. .Iaddend.