Composite material with EMI shielding properties and process to produce it
摘要
說明書
The at least one polypropylene resin can be produced by polymerizing propylene and one or more optional comonomers, in the presence of a catalyst being a metallocene catalyst or a Ziegler-Natta catalyst.
In a preferred example, the catalyst system may comprise a Ziegler-Natta catalyst. The term “Ziegler-Natta catalyst” refers to catalysts of the general formula MXn, wherein M is a transition metal compound selected from groups IV to VII, wherein X is a halogen, and wherein n is the valence of the metal. Preferably, the metal is titanium, chromium or vanadium. Most preferably, the metal is titanium.
The Ziegler-Natta catalyst system, under the disclosure, comprises a titanium compound having at least one titanium-halogen bond and an internal electron donor, both on a suitable support, an organoaluminium compound, and an optional external electron donor. Suitable support is, for example, a magnesium halide in an active form. A suitable external electron donor (ED) is, for example, phthalate or succinate or a diether compound. The organoaluminium compound used in the process of the present disclosure is triethyl aluminium (TEAL).
Advantageously, the triethyl aluminium has a hydride content, expressed as AlH3, of less than 1.0 wt. % for the triethyl aluminium. More preferably, the hydride content is less than 0.5 wt. %, and most preferably, the hydride content is less than 0.1 wt. %. It would not depart from the scope of the disclosure if the organoaluminium compound contains minor amounts of other compounds of the trialkyl aluminium family, such as triisobutyl aluminium, tri-n-butyl aluminium, and linear or cyclic alkyl aluminium compounds containing two or more Al atoms, provided they show polymerization behaviour comparable to that of TEAL.
