pps proceeding - Abstract Preview
pps proceeding
Symposium: S04 - Injection Molding and Molds
Keynote Presentation
 
 

NEW APPROACH TO ELECTROMAGNETIC INTERFERENCE (EMI) SHIELDING OF PLASTIC PARTS USING IN MOLD COATED (IMC) NANOPAPER

Cabrera Eusebio (1), Ko Seunghyun (1), Ouyang Xilian (1), Castro Jose M (1)*, Lee James L (1), Straus Elliott (2)

(1) The Ohio State University - Columbus, Ohio - USA, (2) OMNOVA Solutions Inc. - Akron, Ohio - USA

Plastics with good electric conductivity are becoming the material of choice for many applications where both light weight and conductivity are critical. The challenge is to convert inherently insulating thermoplastic materials to a product that provides antistatic or electronic dissipative or EMI shielding or a combination of these properties. The surface conductivity requirements vary depending on the desired application. There are three approaches used to date to produce electrically conductive plastic products. One is coating with conductive metals or particles. Although highly conductive, such coating suffers low stability and high cost. The second is to use polymer composites filled with conductive fillers such as carbon black, carbon nanofibers or carbon nanotubes. The resulting composites, however, are often not very conductive unless using very high filler loading. The third approach is to use intrinsically conductive polymers which also face major limitations such as poor process ability and high toxicity. This study presents a new approach to provide surface conductivity to the levels required by EMI shielding for injection molded parts. It combines the use of conductive carbon nanopapers and in mold coating (IMC) in the plastic injection molding process. IMC has been used successfully for many years to provide conductivity for further electrostatic painting for compression molded exterior body panels made from Sheet Molding Compound (SMC). The coating is a thermosetting liquid containing about 3% of carbon black (CB). With current conductivity levels, it cannot achieve EMI shielding. Adding more CB and or more conductive fillers increases the viscosity to levels where coating is not possible, as shown in this presentation. In the new approach, conductivity comes from the nanopaper. A model of the new process is presented; values of electrical conductivity as well as EMI shielding effectiveness (SE) were measured.