Method for preparing composition suitable for electrostatic painting

A method for preparing a composition having a melt viscosity of between 160 Pas and 400 Pas, as determined according to ISO-11443-2014 at 270° C. and a shear rate of 265 1/s, and a volume resistivity of at most 105 Ohm·cm, as measured according to ASTM D257 on an injection molded test sample of 3 mm thickness and a diameter of 50 mm and coated with a gold layer on an upper and lower surface, the method comprising the following steps:

• (i) providing a polybutylene terephthalate (PBT) having a relative solution viscosity (RSV) of between 1.6 and 2.4 as measured at 25° C. in meta-cresol according to ISO 1628-5, in an amount of between 40 and 70 wt % with respect to the total weight of the composition;
• (ii) providing a polyethylene terephthalate (PET) having a relative solution viscosity (RSV) of between 1.1 and 1.5 as measured at 25° C. in dichloro acetic acid according to ISO 1628-5, in an amount of between 10 and 40 wt % with respect to the total weight of the composition;
• (iii) providing a filler in an amount of between 10 and 30 wt % wherein the filler is chosen from the group consisting of glass fibers, talc, mica, wollastonite, glass beads and milled glass and combinations thereof, wt being with respect to the total weight of the composition;
• (iv) providing an electrically conductive additive in an amount between 2 and 10 wt % with respect to the total weight of the composition, wherein the electrically conductive additive is chosen from the group consisting of carbon black, carbon fibers, graphite, carbon nanotubes, and graphene and combinations thereof and wherein the electrically conductive additive exhibits a volume resistivity of at most 105 Ohm·cm, as measured according to ASTM D257 on an injection molded test sample of 3 mm thickness and a diameter of 50 mm, consisting of 8 wt % of electrically conductive additive and 92 wt % of PBT having a relative solution viscosity of 2.0 in meta cresol, wherein the wt % is with respect to the total weight of the injection molded test sample, which injection molded test sample was coated with a gold layer on an upper and lower surface;
• and
• (v) mixing at least the PBT, PET, filler and electrically conductive additive at a temperature of between 240 and 260° C. in order to obtain the composition.