In most plastic manufacturing applications, electrical conductivity is an afterthought — or not a thought at all. The polymer does its job, the colour looks right, and the part performs as intended. But in hazardous environments, the electrical properties of a plastic component are not incidental. They can be the difference between safe operation and a catastrophic ignition event.
For processors and product designers working across the oil and gas, chemical processing, mining, and bulk materials handling sectors, understanding the differences among antistatic, static dissipative, and fully conductive masterbatches — and knowing which is required for a given application — is a fundamental technical requirement. This article explains the key distinctions and the considerations that should guide specification decisions.
Why Static Charge Matters in Hazardous Areas
Plastics are, by their nature, electrically insulating. Left unmodified, a polymer component will accumulate electrostatic charge through contact and separation — a phenomenon known as triboelectric charging. In benign environments, the resulting discharge may be no more than an occasional nuisance. In a hazardous area, where flammable gases, vapours, dusts, or fibres may be present, an electrostatic discharge can provide the ignition energy needed to trigger a fire or explosion.
The energy required to ignite common flammable materials is remarkably small. Hydrogen, for example, has a minimum ignition energy of around 0.017 millijoules. Even less sensitive materials such as propane or diesel vapour can be ignited by discharges well within the range that an unmodified plastic component can generate. The consequences are severe, and the regulatory framework — including ATEX in Europe and DSEAR in the UK — reflects this.
For plastic components used in ATEX-classified zones, surface resistivity and charge decay characteristics are not optional performance criteria. They are compliance requirements.
The Conductivity Spectrum: Three Distinct Categories
Electrically functional masterbatch and compounds do not occupy a single point on the performance scale. There are three distinct categories, each defined by measurable surface or volume resistivity, and each suited to different application requirements.
Antistatic masterbatch operates by reducing the tendency of a surface to accumulate static charge in the first place. Typically based on migratory antistatic agents — fatty acid derivatives, amines, or similar compounds — these additives bloom to the surface of the moulded part and attract atmospheric moisture, which provides a thin conductive layer. The effect is surface-resistivity-dependent and is influenced by ambient humidity. Antistatic masterbatch typically achieves surface resistivities in the range of 10⁹ to 10¹¹ ohms per square. Whilst useful in general packaging and consumer goods applications, this performance level is generally insufficient for use in classified hazardous areas, where charge decay must be reliable and humidity-independent.
Static dissipative masterbatch achieves permanent, humidity-independent conductivity through the incorporation of conductive additives — most commonly carbon black at controlled loading levels, or increasingly, carbon nanotubes and other advanced conductive fillers. Surface resistivities in the range of 10⁵ to 10⁹ ohms per square allow controlled, gradual discharge of accumulated charge, avoiding the rapid discharges associated with fully conductive materials whilst providing reliable protection against charge build-up. This category is the most widely specified for hazardous area applications, covering components such as containers, pipes, fittings, conveyor parts, and equipment housings used in ATEX Zones 1, 2, 21, and 22.
Fully conductive compounds achieve surface resistivities below 10⁵ ohms per square and, in some formulations, approach metallic conductivity. At these levels, charge dissipation is rapid and reliable under virtually any conditions. Fully conductive materials are specified for applications requiring electromagnetic shielding, electrostatic painting processes, or where the highest level of conductivity assurance is needed — such as fuel system components, underground cable ducting, and certain bulk container linings.
Key Considerations When Specifying for Hazardous Areas
The ATEX Zone classification of the application — the zone classification (gas/vapour versus dust, and the likelihood of an explosive atmosphere being present) will directly inform the performance tier required and may mandate specific surface resistivity limits. Zones 0 and 20 (continuous hazard) demand the most exacting specifications; Zones 2 and 22 (occasional hazard) allow greater flexibility, but the obligation to control electrostatic risk remains.
The base polymer — conductivity is not a property of the additive in isolation; it is an outcome of the additive-polymer system. The same carbon black loading will behave differently in polyethylene than in polypropylene or polyamide. The percolation threshold — the point at which enough conductive filler is present to form a continuous conductive network through the matrix — varies significantly between polymer types. A masterbatch manufacturer with genuine formulation experience will be able to advise on the appropriate grade for the specific carrier polymer in use.
Processing conditions — conductive masterbatch is more sensitive to processing variables than standard colour or additive masterbatch. Excessive shear during compounding or moulding can disrupt the conductive network formed by carbon black agglomerates, reducing conductivity in the finished part. Melt temperature, back pressure, and screw speed all warrant attention. Similarly, regrind content can affect conductivity consistency and should be managed carefully.
Testing and verification — specifying a conductive masterbatch is only part of the obligation. The finished component must be tested to confirm it meets the required resistivity limits. Standards such as BS EN 61340-2-3 (for surface resistivity measurement) and BS EN 13463 (for non-electrical equipment for use in potentially explosive atmospheres) provide the relevant test methodologies. Where ATEX compliance is a certification requirement, test documentation should form part of the technical file.
Abbey Masterbatch EC Range
Abbey Masterbatch has developed the EC Range of conductive compounds and masterbatch specifically for applications where permanent electrical conductivity is required. The range is designed for use across varying conductivity levels, from static dissipative through to fully conductive, and is available in a variety of polymer carrier systems to suit the processor’s base material.
As an ISO 9001-certified manufacturer with over four decades of formulation experience, Abbey Masterbatch works with customers across a wide range of industries and geographies — including sectors where the consequences of static-related failure are most serious. Export sales account for over 70% of our business, and our technical team is experienced in supporting customers through the specification process, from initial application assessment through to production trials and testing.
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