Modified polypropylene having improved processability

摘要

A modified propylene homopolymer (I) and/or modified propylene copolymer (II) having improved processability is prepared from a propylene homopolymer (III) having a melt index of 0.05 - 35 g/10 min at 230 degrees C and 2.16 kp and/or a copolymer (IV) containing 85-99.9 wt.% propylene and 0.1-15.0 wt.% alpha -olefins having 2 and/or 4-18 C atoms having a melt index of 0.05-45 g /10 min at 230 degrees C and 2.16 kp and ethylenically multi-functional unsaturated monomers. (I) and/or (II) are prepared in a continuous process in which (I) and/or (II) in the form of powder or granules with a particle size of 0.001-7, preferably 0.05-4 mm, optionally with the addition of 0.05-3 wt.% of a thermally decomposable radical initiator (V), preferably acyl peroxides, alkyl peroxides, hydroperoxides, peroxycarbonates and/or peresters are reacted with a gas mixture comprising 5-65 vol. % of a volatile, ethylenically multifunctional unsaturated monomer, preferably a 4-10C diene and/or 7-10C divinyl compound and 95-35 vol. % inert gas and/or oxygen. (I) and (II) are mixed continuously, optionally with the addition of (V), with the gas mixture at 20-120 degrees C, preferably 60-100 degrees C and an average residence time of 10-1000, preferably 60-600s in the solid phase whereby the absorbed portion of the unsaturated monomer is 0.01-10, preferably 0.05-2 wt.%. The material containing absorbed monomer is melted at 110-210 degrees C for 0.3-8.0 minutes under the gas mixture followed by heating to 220-300 degrees C for 0.3-7.0 minutes to remove unreacted monomer and decomposition products. The melt is then formed into a granulate. Additional additives, preferably 0.01-2.5 wt.% stabilisers, 0.1-1 wt.% antistatic agents, 0.2-3 wt.% pigments, 0.05-1 wt.% nucleation agents, 5-40 wt.% filler and/or reinforcing agents and/or 0.01-5 wt.% processing aids are optionally added during any stage of the process apart from the sorption step.