# Flame-retardant adhesive tapes

Vincent Leon

► To cite this version:

Vincent Leon. Flame-retardant adhesive tapes. FRPM25 - 20th European Meeting on Flame-Retardant Polymeric Materials, Jun 2025, Madrid, Spain. hal-05104062

HAL Id: hal-05104062

https://hal.science/hal-05104062v1

Submitted on 19 Jun 2025

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# FLAME-RETARDANT ADHESIVE TAPES

V. Leon

Lohmann GmbH & Co. KG, Irlicher Strasse 55, 56567 Neuwied, Germany

**Main message:** Adhesives too need to be flame retardant (FR). After having been largely ignored for a long time, adhesives are now also taken into consideration for protection against fire so they cannot be the weak point of a composite structure. Most of the flame-retardant additives used for materials can be applied to adhesive systems, but with a key specificity: flame retardancy property should not overtake adhesion power, which remains the principal function of a joint material.

**Keywords:** adhesive tape; flame retardant; halogen-free; pressure sensitive adhesive.

## Introduction

The constantly growing demand for adhesive solutions goes hand in hand with the development of innovative FR compounds, adhesive systems being special materials, delivering their full potential at both the bulk and the interface level. An efficient adhesive needs both characteristics, and the introduction of fillers has a direct effect on both. In the case of thin films like PSAs, compatibility with different adhesive formulations, being in solvent, in water or in bulk, remains a challenge.

## Experimental

Flame test methods follow the standards of FMVSS 302 and UL 94 for horizontal and vertical positions, with an exposure to the flame of 15 s for the horizontal position (FMVSS 302), and 3 s for the vertical position (UL 94 VTM).

Adhesion peel strength is carried out in accordance with DIN ISO 1939 under standard conditions (23°C., 50% relative humidity).

## Results and Discussion

Like other kinds of materials, many different FR exist for adhesive systems. How to select the proper material depends on several factors, with the main one being compatibility with the adhesive matrix. This remark is of course valid for all materials, but it is particularly critical for adhesives which have a double important role as a bulk (cohesion) and at the interface (adhesion). A wrong compatibility will have an impact on both characteristics, and consequently on the overall efficiency of the adhesive [1].

Inorganic additives such as ATH or MDH, known and used for long time, present the double advantage of being easily available and cheap. Nevertheless, their efficiency depends drastically on the amount introduced in the material matrix, which at some point has a direct impact on the adhesion properties of the adhesive. Replacement or combination with inorganic additives is a solution to overcome this issue, but harsher environmental regulations limit the choice of available compounds [2]. In particular, halogen-based additives are on the verge of being totally banned sooner or later, and some organophosphorus are also seriously screened. Alternative solutions like DOPO derivatives already exist, and are extensively reported in the literature and their commercialization is developing [3].

Domains of applications for flame retardant adhesive tapes are diversifying quickly, from construction to transportation, with a special focus for EV-batteries where adhesive tapes solutions are seen as major players for thermal runway problems [4].
<figure><img src="image_1.png" /><figcaption>**FIGURE 1.** Application of flame-retardant adhesive tapes against thermal runaway. © Lohmann GmbH & Co. KG</figcaption></figure>

**References:**

1. Budde F, Strebl-Pfarr M, Homann V. Flame-retardant pressure-sensitive adhesive. 2021, US patent 2021/0147725 A1.

2. Park EY, Kim HG, Lim JC, Lee DH, Min KE. Preparation and flame retardancy of 2-EHA/n-BA acrylic PSA containing single and combined flame retardants. J Appl Polym Sci 2010;117(5):3092-3097.

3. Tang G, Tao Y, Wu Q, Shen H, Sun J, Deng D, Liu X. DOPO-based derivatives with different phosphorous oxidation states as highly efficient flame retardants for epoxy resins. Polym Bull 2024;81(7):6131-6148.

4. Mariappan T, Wilkie CA. Flame retardant epoxy resin for electrical and electronic applications. Fire Mater 2014;38(5):588-598.