Most conventional plastics, including polyethylene (PE), have a high electrical surface resistance. As a result, they tend to accumulate electrostatic charges when subjected to friction, separation, contact with other materials or movement during processing and handling.
Depending on the material formulation and environmental conditions, the surface resistance of untreated plastic films can exceed ohms. The resulting electrostatic charge can attract dust and other particles, interfere with sensitive production processes and, under certain conditions, cause electrostatic discharges or sparks.
For packaging films, these effects can be undesirable. Dust attraction can compromise product cleanliness, while electrostatic discharges may damage sensitive electronic components or create ignition risks in environments containing flammable substances.
Antistatic and electrically conductive polyethylene films are designed to reduce these risks by controlling the accumulation and dissipation of electrostatic charges. The appropriate solution depends on the intended application, the required electrical properties and the conditions under which the film will be used.
Antistatic PE Films: How Do They Work?
Antistatic polyethylene films are commonly produced by incorporating suitable antistatic additives into the polymer during manufacturing. These additives modify the electrical behaviour of the film surface and help reduce the accumulation of electrostatic charges.
The effectiveness of an antistatic additive depends on its chemical composition, concentration, compatibility with the polymer, migration behaviour and the surrounding environmental conditions.
Migrating Antistatic Additives
Conventional antistatic additives often contain polar or hydrophilic substances, such as fatty acid esters and amides, ethoxylated amines or alkyl sulfonates. These substances are generally not fully compatible with the non-polar polyethylene matrix and can gradually migrate towards the film surface.
At the surface, the additives form a thin layer that can absorb moisture from the surrounding air. This moisture increases the surface's ability to conduct electrical charge, allowing accumulated charges to dissipate more readily.
The effectiveness of this mechanism depends significantly on relative humidity, temperature, additive concentration and the time required for the additives to migrate to the surface.
Migrating antistatic additives are therefore particularly useful when a reduction in surface charge is required during film processing, packaging or handling. However, their performance can vary under dry conditions, and their effectiveness may change over time because of migration, surface contact, cleaning or other environmental influences.
Typical Surface Resistance of Antistatic Films
Depending on the additive system, concentration and film formulation, antistatic additives can reduce the surface resistance of polyethylene from values above ohms to approximately – ohms.
These values are indicative and should not be interpreted as guaranteed specifications for every antistatic PE film. The actual surface resistance must be determined through measurement under defined test conditions.
Antistatic performance should also be evaluated in relation to the application. A reduction in surface resistance can help prevent charge accumulation, but it does not automatically mean that a film is electrically conductive or suitable for every electrostatic-sensitive environment.
Permanent Antistatic Properties Through Hydrophilic Polymers
In applications where a more durable antistatic effect is required, hydrophilic polymers can be incorporated into the material formulation. Certain polymer systems, including suitable polyamide-based copolymers, can provide antistatic functionality through a different mechanism from conventional migrating additives.
These materials can form moisture-attracting pathways that facilitate charge dissipation. Depending on their chemical structure, distribution within the polymer and compatibility with the surrounding material, they may provide a more persistent antistatic effect.
Unlike conventional surface-migrating additives, appropriately designed polymeric antistatic systems can reduce dependence on the formation of a temporary surface layer. Nevertheless, their performance still depends on the specific formulation, processing conditions and environment.
The term permanent antistatic should therefore be understood in relation to the durability demonstrated by the particular material. Long-term performance should be confirmed through appropriate electrical measurements and ageing tests.
Electrically Conductive PE Films Using Carbon Black
For applications requiring substantially lower electrical resistance, electrically conductive polyethylene or polyolefin compounds can be produced by incorporating conductive carbon black into the polymer matrix.
Conductive carbon black creates an interconnected network of conductive particles within the material. When the concentration and dispersion are suitable, this network allows electrical charges to move through the compound rather than relying primarily on moisture at the film surface.
The electrical performance depends on several factors, including carbon black type, particle structure, concentration, dispersion quality and the properties of the polymer matrix. A sufficiently developed conductive network is essential to achieving low electrical resistance.
Our PLE Conductive Film
Our PLE product uses conductive carbon black at a concentration of approximately 15% in a polyolefin compound to achieve a reported electrical resistance of around ohms.
Due to the carbon black content, the film is black. This coloration is an inherent characteristic of the formulation and is directly associated with the conductive material used.
The product is designed for applications in which electrical charge dissipation or conductivity is required. Its suitability for a particular application depends on the applicable resistance requirements, the measurement method and the intended operating conditions.
For technical applications, the relevant electrical specification should clearly identify whether the stated value refers to surface resistance, volume resistance or another electrical parameter. These measurements describe different properties and should not be used interchangeably.
Antistatic vs. Electrically Conductive Films
Antistatic and electrically conductive films both help control electrostatic charge, but they do not necessarily achieve this through the same mechanism or provide the same level of electrical performance.
Antistatic films are primarily designed to reduce the accumulation of static charge. They often use additives that modify surface behaviour and can facilitate charge dissipation.
Electrically conductive films, by contrast, use conductive components such as carbon black to create pathways through which electrical charges can move. These materials can achieve substantially lower resistance values when the formulation is designed accordingly.
The most suitable material depends on the application:
- Antistatic PE film: Suitable where reducing static charge accumulation and dust attraction is the main objective.
- Polymeric antistatic film: An option where a more durable antistatic effect is required, subject to verification of long-term performance.
- Conductive PE film: Suitable for applications requiring a defined level of electrical conductivity or charge dissipation, provided the measured properties meet the relevant requirements.
It is important to distinguish between antistatic performance, charge dissipation and electrical conductivity. A film described as antistatic is not automatically suitable for protecting sensitive electronic components or for use in potentially explosive atmospheres.
How Is Electrostatic Charge Measured?
Electrostatic charge and the electrical resistance of a material are related but distinct properties. They should therefore be assessed using appropriate measurement methods.
An electrostatic field meter can be used to measure the electric field near an object and estimate its electrostatic potential under specified measurement conditions. This helps determine whether a film or package has accumulated an electrostatic charge.
However, a field meter does not directly measure the electrical surface resistance of the film. Surface resistance requires a suitable resistance-measurement method and appropriate electrodes. Depending on the application, charge decay or charge-dissipation measurements may also be necessary.
A film that shows little or no measurable electrostatic potential at a particular moment is not necessarily antistatic. It may simply have been discharged before measurement. Reliable classification therefore requires testing the material's electrical properties and charge behaviour under defined conditions.
For meaningful comparisons, measurements should account for factors such as relative humidity, temperature, conditioning time, electrode configuration, applied voltage and the relevant test standard.
Applications of Antistatic and Conductive PE Films
Antistatic and conductive polyethylene films are used in a wide range of industrial and packaging applications where electrostatic behaviour must be controlled.
Typical applications include:
- Packaging and handling: Reducing electrostatic charge accumulation and limiting dust attraction during film processing and packaging.
- Electronics packaging: Supporting electrostatic charge control when packaging electronic components, provided the film meets the required electrostatic discharge (ESD) specifications.
- Industrial protective films: Helping manage static charge during storage, transport and handling of sensitive products.
- Technical packaging: Providing tailored electrical properties for specialized industrial requirements.
- Charge-dissipative applications: Supporting the controlled dissipation of electrostatic charge when the measured resistance and charge-decay performance meet the relevant requirements.
For applications involving sensitive electronics or potentially explosive atmospheres, the complete packaging system and its intended use must be evaluated against the applicable safety and performance standards.
Selecting the Right Antistatic or Conductive Film
Selecting the appropriate film begins with defining the required electrical performance. Important considerations include the target surface or volume resistance, the required charge-decay behaviour, the operating environment, the expected service life and the sensitivity of the packaged product.
Conventional antistatic additives may be sufficient where the main objective is to reduce static charge accumulation. Polymeric antistatic systems may be preferable where more persistent performance is required. For applications requiring substantially lower electrical resistance, a carbon-black-based conductive compound may be the appropriate solution.
The final choice should be based on measured material properties rather than on product descriptions alone. Testing under representative environmental conditions helps establish whether the film meets the requirements of the intended application.
By selecting the appropriate formulation, antistatic additive system or conductive compound, manufacturers can obtain polyethylene films with electrical properties tailored to specific packaging and industrial applications.
Further information on the subject of surface resistance can be found here.
