Production of maleinized polypropylene, for use e.g. as a coupling agent in polymer composites, involves reacting polypropylene with maleic anhydride and peroxide initiator at elevated temperature in the solid state

摘要

Maleic anhydride-modified polypropylene is obtained by dispersing polypropylene with specified amounts of maleic anhydride and organic peroxide initiator at up to 120 deg C and then reacting in the dry solid state at 125-160 deg C. A method for the production of maleic anhydride-modified polypropylene with a degree of maleinization of 0.1-5 wt% involves (A) making a reaction mixture comprising (a1) 60-96 wt% polypropylene (PP) powder with an average particle diameter (d50) of 0.01-8 mm, (a2) 2.5-24.5 wt% maleic anhydride (MA), optionally as a mixture of 20-95 parts by weight (pts. wt.) MA and 5-80 pts. wt. comonomer and (a3) 1.5-15.5 wt% organic peroxide initiator with a half-life of 2-150 minutes at reaction temperature (Tr), using a wt. ratio of MA/peroxide = 0.2-20, a dispersion temperature (Td) between room temperature (Tn) and 120 deg C and a dispersion time (tD) of 1-60 min; (B) heating the mixture from Td to Tr (125-160 deg C) over 5-120 minutes; (C) reacting the mixture at Tr in the solid (dry) state for 5-180 min (reaction time, tR) and then; (D) removing unreacted monomer by passing nitrogen through the mixture for 10-240 min at a desorption temperature (Tdes) between Tr and 80 deg C, deactivating the initiator and cooling to between 100 deg C and Tn.