Conductive long fiber thermoplastic compounds for electromagnetic shielding

Abstract

Thermoplastic compounds in the form of a pellet include thermoplastic resin and conductive fibers. The conductive fibers are enveloped by the thermoplastic resin and distributed within the pellet such that each of at least a portion of the conductive fibers is substantially surrounded by the thermoplastic resin and thereby substantially separated from physical contact with any other of the conductive fibers. Additionally, at least a portion of the conductive fibers includes long fibers. The thermoplastic compound, when molded at a thickness of about 3.2 mm, has an electromagnetic shielding effectiveness across a range of frequencies from about 0.5 GHz to about 2.0 GHz of at least about 60 dB according to ASTM D4935, which makes the thermoplastic compound useful for molding thermoplastic articles for shielding against electromagnetic interference.

Description

[0001] priority statement [0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 746,129 (Attorney Docket No. 12018029), filed October 16, 2018, which is incorporated herein by reference. [0003] field of invention [0004] The present invention relates to conductive long fiber thermoplastic compounds and thermoplastic articles molded therefrom, which are useful for shielding against electromagnetic interference. [0005] Background of the invention [0006] Electronic systems, devices and equipment are everywhere. The modern world relies on electronics for numerous markets and industries such as aerospace, automotive, consumer, entertainment, financial, industrial, logistics, manufacturing, medical, retail, telecommunications and transportation. [0007] As electronic devices have grown in popularity, there has been an increasing need for means of shielding electronic devices from electromagnetic interference (EMI), sometimes referred...

AI Technical Summary

Problems solved by technology

However, to meet or exceed typical EMI / RFI shielding requirements, relatively high levels of conductive filler may be required

Disadvantageously, conductive plastics that include relatively large amounts of conductive fillers may have relatively higher costs and relatively greater processing, molding, and manufacturing difficulties than conductive plastics that include relatively small amounts of conductive fillers

In addition, relatively high amounts of conductive fillers can lead to undesired weight gain in end-use products

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