Masterbatches for preparing a composite material based on semi-crystalline polymer with enhanced conductivity properties, process and composite materials produced therefrom

Abstract

The present invention relates to a masterbatch for use in a process of preparing a composite material comprising a blend of a first semi-crystalline polymer with at least 5 wt % carbon nanotubes. Good dispersion of the carbon nanotube is obtained within the masterbatch and evidenced by the blending of the masterbatch with a second semi-crystalline polymer miscible with the first one in respective proportions to obtain a composite material containing about 1 wt % of carbon nanotubes wherein said composite material yields an agglomerate area fraction U % lower than 2 and a surface resistivity lower than 10 5 ohm/sq.

1 .- 14 . (canceled) 
     
     
         15 . A process for the preparation of a masterbatch comprising the steps of:
 (a) providing carbon nanotubes,   (b) providing a first semi-crystalline polymer having a melting temperature Tm1 as measured according to ISO 11357-3:2013, wherein the first semi-crystalline polymer is selected from syndiotactic polypropylene and isotactic polypropylene, and wherein the first semi-crystalline polymer has a melt flow index comprised between 5 and 250 g/10 min measured according to ISO 1133 under a load of 2.16 kg;   (c) blending together the carbon nanotubes and the first semi-crystalline polymer by extrusion in an extruder comprising a transport zone and a melting zone maintained at a temperature comprised between Tm1+1° C. and Tm1+50° C., and   (d) forming a masterbatch through a die, the masterbatch,
 comprising at least 5 wt % of carbon nanotubes based on the total weight of the masterbatch as determined according to ISO 11358, and 
 having a high load melt index HLMI of from 100 g/10 min to 1000 g/10 min as determined under a load of 21.6 kg according to ISO1133. 
   
     
     
         16 . The process according to  claim 15  wherein the masterbatch comprises from 0.01 to 4.0 wt % of one or more additives based on the total weight of the masterbatch, the one or more additives being selected from waxes, tristearin, zinc stearate, calcium stearate, magnesium stearate, erucyl amide, oleic acid amide, ethylene-acrylic acid copolymer, ethylene vinyl acetate copolymer and cetyl trimethyl ammonium bromide 
     
     
         17 . The process for the preparation of a masterbatch comprising the steps of:
 (a) providing carbon nanotubes,   (b) providing a first semi-crystalline polymer having a melting temperature Tm1 as measured according to ISO11357-3, wherein the first semi-crystalline polymer is polyethylene, and wherein the first semi-crystalline polymer has a melt flow index comprised between 5 and 250 g/10 min measured according to ISO1133 under a load of 2.16 kg;   (c) blending together the carbon nanotubes and the first semi-crystalline polymer by extrusion in an extruder comprising a transport zone and a melting zone maintained at a temperature comprised between Tm1+5° C. and Tm1+30° C., and   (d) forming a masterbatch through a die, the masterbatch comprising
 at least 5 wt % of carbon nanotubes based on the total weight of the masterbatch as determined according to ISO11358, and 
 having a high load melt index HLMI of from 2 g/10 min to 1000 g/10 min as determined under a load of 21.6 kg according to ISO1133. 
   
     
     
         18 . The process according to  claim 17  wherein the first semi-crystalline polymer is polyethylene, in that the temperature in the transport zone and the melting zone of the extruder ranges from 150° C. to 160° C., and/or in that the masterbatch formed has a HLMI ranging from 10 to 100 g/10 min as determined according to ISO1133 under a load of 21.6 kg at a temperature of 190° C. 
     
     
         19 . The process according to  claim 17  wherein:
 the process further comprises the step of blending from 0.01 to 4.0 wt % of one or more additives based on the total weight of the masterbatch with the first semicrystalline polymer and carbon nanotubes in step (c), the one or more additives being selected from waxes, tristearin, zinc stearate, calcium stearate, magnesium stearate, erucyl amide, oleic acid amide, ethylene-acrylic acid copolymer, ethylene vinyl acetate copolymer and cetyl trimethyl ammonium bromide; and/or in that 
 step (c) of blending together the carbon nanotubes and the first semi-crystalline polymer, is carried out on co-rotating twin screw extruder at a screw speed of at least 300 rpm. 
 
     
     
         20 . The process of  claim 17 , wherein the masterbatch comprises an HLMI which ranges from 10 to 100 g/10 min as determined according to ISO1133 under a load of 21.6 kg at a temperature of 190° C. 
     
     
         21 . The process of  claim 17  wherein the masterbatch comprises a first semi-crystalline polymer having a melt flow index ranging from 5 to 250 g/10 min as measured according to ISO 1133 under a load of 2.16 kg.