E-Tunnel (Electronic Tunnel) EVA (Ethylene Vinyl Acetate) has been widely used in the fields of shoe materials and protective gear due to its lightweight and excellent elasticity. Compared with heavy PU cast products, it delivers a lighter user experience; when compared with traditional polyurethane foam, its elastic advantage is more prominent — therefore, it remains the preferred material for engineers engaged in the development of shoe materials and protective gear to this day.

However, in the field of Electrostatic Discharge (ESD) applications, EVA has long been restricted by technical bottlenecks in electrical conductivity, resulting in obvious defects in its application methods. For this reason, developing breakthrough new ESD EVA materials has become an urgent demand in the industry, which is also the core original intention of our project.

I. Core Knowledge of ESD Materials and Limitations of Traditional EVA

The quality core of ESD products lies in their electrostatic discharge capability, and resistivity is the key indicator for measuring their performance. Currently, ESD EVA is mainly divided into two categories:

• Antistatic grade: Weak electrical conductivity (high resistance), complying with the hammer test standard of 10⁶~10⁹ MΩ;
• Conductive grade: Strong electrical conductivity (low resistance), complying with the hammer test standard of 10³~10⁵ MΩ.

(Note: The smaller the value, the better the electrical conductivity; the larger the value, the poorer the electrical conductivity.)

Over the past two decades, the application of ESD EVA has always had technical shortcomings, mainly reflected in two outdated production methods:

1. Non-ESD Substrate Processing Method with Sewn Metal Conductive Wires

Using traditional non-conductive EVA as the substrate, it is processed into insoles or foot pads, and then metal conductive wires are sewn to achieve the conductive function. This method has multiple defects and risks:

• The sewing threads damage the product appearance and affect aesthetics;
• The uneven structure caused by the sewing threads reduces stepping comfort;
• If the conductive wires break or fray, the product will completely lose its ESD performance;
• There is a risk of broken needle residues. If detection is overlooked, it may pose safety hazards to end users.

2. Traditional EVA Foam with Improper Conductive Substances Added

Specifically, electrostatic conduction is achieved by mixing conductive substances into EVA foam, but the drawbacks of such products have long been criticized:

• The substances are difficult to disperse evenly, easily leading to a large number of defective raw materials;
• The electrostatic conduction performance is significantly limited, only reaching 10⁸~10⁹ MΩ (close to 10¹⁰ MΩ of insulators); moreover, the tear strength of EVA foam is very poor, which easily causes the product to deform under stepping and break.
• The stability of conductive performance is extremely poor, greatly affected by air humidity. Even in dry environments or seasons, its conductive performance may decline seriously or even become completely insulating.

To sum up, the conductive insole and antistatic insole produced from traditional ESD EVA foam not only have poor quality but also bear serious quality hazards. To change this situation and enhance the application value of EVA in the ESD field, we have launched the R&D project of the new E-Tunnel EVA insole material.

II. R&D Breakthroughs and Product Advantages of E-Tunnel^TM EVA

Over the past 3 years, based on overcoming the E-Tunnel fabric conductivity technology, we have carried out special research on ESD EVA. By testing dozens of conductive media, we finally achieved a technological breakthrough — the conductive insoles produced by combining independently developed E-Tunnel EVA with E-Tunnel fabric not only have excellent physical properties but also possess superior conductive capabilities: after repeated testing, their resistance is stably maintained at 10³~10⁵ MΩ (hammer test method), and in the intuitive current conduction test, they can directly light up the detection bulb.

The core advantages of E-Tunnel EVA insoles are as follows:

• Excellent physical properties: Avoids problems such as material stiffness and easy cracking caused by uneven dispersion;
• Washable and anti-aging: Performance will not degrade due to washing or long-term use;
• Strong environmental adaptability: Completely unaffected by air humidity, with stable and consistent performance in any environment;
• Aesthetic appearance: No need to sew conductive wires, maintaining a flat and beautiful product surface.

III. Product Description and Application Prospects

At present, E-Tunnel EVA can only stably produce black or dark gray products. Other colors are prone to obvious color differences, so they are not recommended for the time being; the product hardness is recommended to be set at 40~60° (Shore C), and products below 40° are not recommended for the time being.

We believe that the advent of E-Tunnel EVA insoles will break the shackles of traditional technology, expand the application boundaries of EVA in the ESD field, and significantly improve the quality and value of end products.

We look forward to your inquiry and hope our products will empower your business!

Author: shineway/BillWang