Anti-Static PPE: Combining Worker Safety and Production Efficiency

Personal protective equipment (PPE) is crucial for ensuring the safety and well-being of individuals in work environments. It encompasses a wide range of items, including hand, body, head, and foot protection designed to mitigate risks from various hazards in the workplace. The specific types of PPE required depend on the nature of the work and the associated risks. But one critical feature that these items must often possess is anti-static properties.

Where Does Anti-Static Matter in PPE?

In many industrial settings, static electricity can pose a significant hazard. Static electricity is generated by friction. It becomes hazardous with the presence of flammable gases, vapors, or combustible dust as discharges (sparks) can ignite flammable substances, damage sensitive electronic components, and cause electric shocks, leading to worker injuries and device failure. Such environments, called ATEX-sensitive, exist in electronics manufacturing, the petrochemical industry, and areas handling flammable gases or liquids. For example, in electronics manufacturing, up to 33% of production losses are attributed to static-related device failures.^[1] Therefore, anti-static personal protective equipment is essential in these settings. Clothes, gloves, and boots should be conductive, as maintaining an uninterrupted grounding chain is crucial for dissipating static electricity effectively.

ATEX Compliance: Global Standards for Anti-Static PPE

To ensure the effectiveness and safety of anti-static PPE, various standards have been established globally. Here are some of the main standards that specify the requirements and testing methods for anti-static properties in personal protective equipment:

1. EN 1149: This European standard specifies the requirements for electrostatic properties of protective clothing. It includes testing methods for materials to ensure they dissipate electrostatic charges effectively. EN 1149 is divided into several parts, with EN 1149-5 being a common specification for performance requirements.^[2]
2. EN ISO 18080: This European standard pertains to the evaluation of the electrostatic properties of textiles. It provides the testing methods and requirements for determining how well textile materials can dissipate static electricity.^[3]
3. EN ISO 20345: This standard outlines the specifications for safety footwear, including anti-static properties. Footwear conforming to this standard must pass specific tests to ensure it effectively dissipates static electricity.^[4]
4. ASTM F1506: This American standard is used for protective clothing worn by electrical workers. It includes requirements for flame resistance and arc flash protection, along with anti-static properties to prevent static buildup and discharge.^[5]
5. IEC 61340: This international standard focuses on the protection of electronic devices from electrostatic phenomena. It includes guidelines for materials and procedures to control ESD in sensitive environments, applicable to anti-static clothing and gloves.^[6]
6. EN 16350: This European standard specifies the requirements and testing methods for protective gloves that are designed to dissipate static electricity and prevent electrostatic discharge (ESD). The standard specifies that the surface resistivity of the gloves must be less than 10^8 Ω and includes detailed test methods for measuring the surface resistivity of the gloves.^[7]
7. ANSI/ESD STM2.1: This standard, developed by the American National Standards Institute (ANSI) in conjunction with the Electrostatic Discharge Association (ESD) outlines procedures for evaluating the electrostatic properties of garments, including their ability to dissipate static charges effectively.^[8]
8. ATEX Directive 95/2014: This European Union directive (formally known as Directive 2014/34/EU) aims to ensure a high level of protection for workers in environments where explosive atmospheres may occur. It applies to equipment and protective systems intended for use in such environments and sets out essential health and safety requirements that these products must meet.^[9]

How to Provide PPE with Anti-Static Properties

Making personal protective equipment anti-static involves incorporating materials and treatments that can dissipate static electricity and prevent the buildup of electrostatic charges. Here are several methods used to achieve anti-static properties in PPE:

• Incorporation of conductive yarns, including carbon fiber and metallic threads. Integrating these fibers and threads into the fabric helps dissipate static electricity, but it requires a specific knitting process and setup of knitting machinery. Oxidation of copper yarns can result in a short shelf life and color changes, making the handling of conductive fibers more complicated. Additionally, in textile processing, metal fibers have poor cohesion and spinning performance and are expensive when produced with high fineness.^[10]
• Applying conductive coatings to the surface of fabrics or other materials. Traditionally, carbon black is used as a conductive agent. However, high content of this filler (7%)^[11] has several drawbacks, including reduced flexibility and comfort, a carbon release effect, limitations in electrical performance, a high minimum thickness of approximately 0.4 mm, black color limitation, and processing challenges that require special formulation and dipping design. Metallic particles are also used as anti-static PPE coatings, but they face issues such as wearing off over time due to abrasion and regular use, degradation under harsh conditions (such as exposure to chemicals, extreme temperatures, and mechanical stress), increased fabric stiffness and weight, metal allergies among users, particle release, corrosion, and conductivity thresholds. These drawbacks limit the use of metallic particles in anti-static PPE.
• Blending of anti-static materials by combining standard polymers with conductive polymers. For example, blending polyester with carbon-loaded polyethylene. Another option is using inherently conductive polymers (ICPs), such as polyaniline or polypyrrole, which can make the entire fabric conductive and anti-static.^[12] However, there are several drawbacks associated with using ICPs in anti-static PPE, including high material cost, complex processing requirements and compatibility issues, effects on tensile strength and flexibility, and degradation of electrical conductivity over time.

Figure 1. Comparison of working dosages of various conductive fillers.

The unique morphology and properties of graphene nanotubes (GNT) allow them to grant stable anti-static properties and additional functionality to PPE through coating existing material or yarn or modifying the material itself during the production process. The electrical conductivity provided by nanotubes makes it possible to achieve highly valued ESD protection according to the international standards and the required functionality for industrial and cleanroom gloves and protective wear. Additionally, empowered by graphene nanotubes, protective gloves and clothing gain smart properties such as dust repellency and touch-screen compatibility.

Figure 2. The same concentration of various particles (~0.1%) in the same volume.

The exceptional efficiency of nanotubes allows them to work effectively at dosages as low as 0.05 wt.%, providing flexibility in formulation. This enables manufacturers to maintain crucial material properties like flexibility, mechanical strength, color, and chemical resistance. Utilizing pre-dispersed nanotube-based concentrates and dispersions simplifies the handling of graphene nanotubes during production, ensuring clean and efficient processes with standard industrial equipment. By adjusting the dosage, manufacturers can create colored products that seamlessly blend enhanced functionality with aesthetic appeal.

Figure 3. Changes in color and volume resistivity with the addition of graphene nanotubes.

Graphene nanotubes in PPE: case studies and applications

The integration of ESD properties into personal protective equipment via graphene nanotubes represents a significant breakthrough in material functionality. This new approach for the development of PPE compliant with international standards for protective wear without changing standard production technology and equipment is suitable for various PPE items, among which are:

Industrial gloves

Graphene nanotubes offer not only stable, permanent ESD protection but also an anti-static effect that allows seamless touch-screen operation without removing gloves, ensuring both worker and product safety. With graphene nanotubes, you can use standard liners without conductive yarns while maintaining a wide range of colors. Liner PU and nitrile gloves enhanced with just 0.06–0.1 wt.% nanotubes achieve a stable electrical resistance of 10^7 Ω. The unique properties of nanotubes make it possible to maintain resistance to microbial attack, abrasion, alkali, and hydrolysis, while also providing enhanced durability, reliability, and a special soft-feel effect.

Figure 4. Anti-static nitrile film with 0.06 wt.% TUBALLTM nanotubes.

Cleanroom gloves

Fragile and unstable polymer or salt is replaced with a robust nanotube-based conductive solution compatible with all latex types. With 0.06 wt.% graphene nanotubes inside nitrile latex film, gloves comply with EN 16350 and allow for coloration.

Figure 5. EN compliant ESD gloves with TUBALLTM nanotubes. PU & nitrile latexes. *Gloves made by industrial partners with TUBALLTM.

Protective wear

Nanotubes provide clothing with electrical resistance of 10^6–10^8 Ω without impacting the original mechanical properties of the fabric. Protective wear with graphene nanotubes ensures compliance with international anti-static standards and is used for protection against sparks, splashes of molten metal, high temperatures, and the risk of sudden electrostatic discharge. Anti-static metal yarn is replaced with 0.5 wt.% TUBALLTM LATEX H2O (nanotube-based dispersion) added at the fluoroorganic treatment stage. Other applications include silicone textile coatings, PVC-plastisol-based clothing, and fluoroelastomer coating with TUBALLTM MATRIX 601, TUBALLTM MATRIX 814, and TUBALL MATRIX 608, respectively. Additional benefits, such as no carbon release at the surface, no change in production process, and no color limitations, set graphene nanotubes apart from alternatives like carbon black.

Selecting the appropriate personal protective equipment is crucial in hazardous work environments with safety risks. Textiles enhanced with graphene nanotubes offer exceptional wear performance, enabling the creation of multifunctional, comfortable, and reliable products in full compliance with EN, ISO, and ATEX standards for protective wear. This groundbreaking material opens the door to producing top-tier protective suits that combine exceptional protection from chemicals and other workplace hazards with reliable electrostatic discharge protection, boosting the overall efficiency of production processes.

[1] EOS/ESD Association. Fundamentals of Electrostatic Discharge, Part One: An Introduction to ESD, EOS/ESD Association. Inc., Rome, NY [Internet]. 2020. Available from: https://www.esda.org/esd-overview/esd-fundamentals/part-1-an-introduction-to-esd/ 
[2] Standard NEN-EN 1149-5:2018 en. Protective clothing - Electrostatic properties - Part 5: Material performance and design requirements: https://www.nen.nl/en/nen-en-1149-5-2018-en-250671 
[3] Standard ISO 18080-3:2015. Textiles — Test methods for evaluating the electrostatic propensity of fabrics: https://www.iso.org/standard/61384.html
[4] ISO 20345:2021. Personal protective equipment — Safety footwear https://www.iso.org/standard/73222.html
[5] ASTM F1506-22. Standard Performance Specification for Flame Resistant and Electric Arc Rated Protective Clothing Worn by Workers Exposed to Flames and Electric Arcs: https://www.astm.org/f1506-22.html
[6] IEC 61340-5-3:2022. Electrostatics - Part 5-3: Protection of electronic devices from electrostatic phenomena - Properties and requirements classification for packaging intended for electrostatic discharge sensitive devices: https://webstore.iec.ch/publication/64718
[7] Standard EN 16350 - Electrostatic properties: https://www.mapa-pro.com/standards/standard-en-16350-electrostatic-properties
[8] ANSI/ESD STM2.1-2018. Garments - Resistive Characterization: https://webstore.ansi.org/standards/esda/ansiesdstm22018
[9] ATEX 114 directive 2014/34 / EU: https://www.mibex.nl/en/ex-regulations/atex-95
[10] Hubei Decon. Static Electricity in Textiles: https://www.polyestermfg.com/static-electricity-in-textiles/
[11] Patent application of Dipped Products Plc (July 2014) A latex article with static dissipating property: https://patents.google.com/patent/WO2015022590A1/en
[12] Ana M. Grancarić, Ivona Jerković, Vladan Koncar, Cedric Cochrane, Fern M. Kelly, Damien Soulat, Xavier Legrand. Conductive polymers for smart textile applications. First published online March 16, 2017. Journal of Industrial Textiles. https://doi.org/10.1177/1528083717699368