Composite material with EMI shielding properties and process to produce it
摘要
說明書
The average molecular weight of the rubber, for which the intrinsic viscosity is a measure, is controlled by the addition of hydrogen to the polymerization reactors of the second polymerization stage. The amount of hydrogen added is such that the rubber has an intrinsic viscosity of at least 2.0 dl/g, and of at most 5.5 dl/g, measured in tetralin at 135° C. following ISO 1628. The contribution of the second polymerization stage, i.e. the rubber content of the heterophasic propylene copolymer is from 5 to 50 wt. % relative to the total weight of the heterophasic propylene copolymer.
After the last polymerization reactor, the polymers are recovered as a powder and can then be pelletized or granulated.
Examples of polypropylene resins suitable to be used as component A are commercially available from Total?. A non-limitative example is PPC7760 with a melt index MI2 of 15.0 g/10 min. Another example is PPH 7060 with a melt index MI2 of 12 g/10 min. Another example is PPC 6742 with a melt index MI2 of 8 g/10 min. Another example is MH140CN0, with a melt index MI2 of 140 g/10 min. All MI2 are determined according to ISO 1133 at 230° C. under a load of 2.16 kg.
For example, the at least one polypropylene resin is selected from a virgin polypropylene resin, a polypropylene post-consumer resin and a blend of a virgin polypropylene resin and a polypropylene post-consumer resin.
In one or more embodiments, the at least one polypropylene resin comprises a post-consumer polypropylene resin at a content ranging from 5 to 100 wt. % of polypropylene post-consumer resin based on the total weight of component A; for example, from 20 to 95 wt %; for example, from 40 to 90 wt. %; for example, from 50 to 85 wt. %; for example, from 60 to 80 wt %.
