Electrically conductive plastic compounds have good growth opportunities

Generally plastics are electrically insulating. Infact, their insulation properties have made them ideally suitable for wire, cable as well as several other electrical applications. There are however newer applications wherein Plastics' insulating properties are a liability.

Due to an intensive usage of electronics in consumer products and increasing miniaturization of products, a need to protect these parts from Electrostatic Dissipation (ESD) and Electromagnetic Interference (EMI) shielding arises. An increasing shift to electrostatic painting of automotive and industrial parts require paintable plastic products, which in turn demands plastic materials to be electrically conductive.

The conductive thermoplastic market in North America has reached a level of 225 Kt in 2001. It is expected to grow at about 8-10% in the next 5 years.

Thermoplastic compounders have obtained better conductivity by incorporating Carbon black, Carbon fibers, Aluminium flakes or Stainless Steel fibers. Newer polymers with intrinsic capability of conductivity are being developed. These polymers with different degree of conductivity are known as Inherently Conductive Polymers (ICP) or Inherently Dissipative Polymers (IDP).

They are very efficient in creating conductive networks when alloyed with a conventional thermoplastic polymer. The most commonly known ICP is Polyaniline, manufactured by Panipol of Finland. IDPs are generally elastomers that contain "charge carrying blocks". These blocks have the ability to conduct electricity. The IDP polymer range developed by Noveon (BF Goodrich, formerly) can be used in the matrix of Styrenics, PETG and PP. In recent years, several compounders like DSM, Lati, LNP and RTP have developed IDP based compounds with surface resistivity ranging from 10³-10¹¹ ohm/sq mm.

Carbon black, so far is the workhorse for conductive plastics business due to its low cost. However, it has two major limitations. Carbon black can only provide black colour. Other colours are extremely difficult to produce, if not impossible. Carbon black can also damage sensitive microelectronic devices.

ICP and IDP based conductive products are very efficient in conductivity and are more amenable to colouring. Another development is of very efficient carbon nano-tubes or nano-fibres which can impart high conductivity at lower loadings. Their usage is presently limited because of prohibitively higher cost. However nano-carbons are expected to prove indispensable in future. These nano-carbons are supplied by Mitsui and Showa Denko from Japan and Hyperlon catalysts from USA. For improved dispersion, some of the suppliers like Hyperlon provide them in the form of masterbatches. They are quite efficient and require less than 50% loading compared to carbon black.

A new type of carbon fiber from pitch developed by Conoco is expected be more efficient than carbon fibers based on PAN.

To eliminate colorability problem of carbon black, stainless steel fibers are widely used, particularly in cell phones, etc to avoid electromagnetic interferences.

The options for achieving electrical conductivity are indeed increasing in this growing market.