Masterbatches for Preparing Composite Materials with Enhanced Conductivity Properties, Process and Composite Materials Produced

A process for preparing a composite material comprising a polymer composition and carbon nanotubes, characterized in that said polymer composition comprises a mixture of a first and a second amorphous polymer and the composite material comprises from 0.05 to 1.95% by weight of carbon nanotubes based on the total weight of the composite material as determined according to ISO 11358, and in that the composite material has a surface resistivity of at most 1×104 Ohm/sq, said process comprising the steps of:

• b. providing a masterbatch comprising a first amorphous polymer and at least 5%, and preferably from 5% to 15%, by weight of carbon nanotubes based on the total weight of the masterbatch as determined according to ISO 11358, and wherein the first amorphous polymer has a melt flow index MFI1 of at least 10 g/10 min determined at 200° C. under a load of 5 kg according to ISO1133H, wherein the first amorphous polymer is selected from the group consisting of polystyrene, modified-polystyrene, acrylonitrile-butadiene-styrene, polycarbonate, styrene acrylonitrile, poly(methyl methacrylate), poly(vinyl chloride), polybutadiene, polybutylene terephthalate, poly(p-phenylene oxide), polysulfone, polyethersulfone, polyethylenimine, polyphenylsulfone, acrylonitrile styrene acrylate and any combination thereof, wherein the masterbatch comprises at least 80% by weight of the first amorphous polymer, and wherein the masterbatch comprises a surface resistivity of at most 1×102 Ohm/sq as determined according to CEI 60167;
• c. providing a second amorphous polymer having a glass transition temperature Tg2;
• d. blending together the masterbatch and the second amorphous polymer by extrusion in an extruder at a barrel temperature ranging from Tg2+100° C. to Tg2+200° C., preferably ranging from Tg2+120° C. to Tg2+180° C.,
• the glass transition temperature being determined according to according to ISO 11357-2:2013.