What factors will affect the flame retardancy of high temperature adhesive tape?

Base material composition of adhesive tape

Polymer type: Different polymers as the base material of adhesive tape have different flame retardancy. For example, polyimide (PI) is a common high-temperature adhesive tape substrate, which has certain inherent flame retardancy. This is because polyimide molecular structure contains a large number of aromatic rings, which make the material have high thermal stability and flame retardancy. However, when some common plastics such as polyethylene (PE) are used as the base material of adhesive tape, the flame retardancy is relatively poor, because its molecular chain is mainly composed of carbon-hydrogen (C-H) bonds, which are easy to break and burn at high temperature and flame.

Influence of additives: In order to improve the flame retardancy of tape substrate, flame retardants are often added. The type and amount of flame retardant have significant influence on the flame retardant performance of adhesive tape. For example, halogen flame retardants (such as bromine flame retardants) can release hydrogen halide gas during combustion, which can interfere with the free radical reaction of combustion, thus achieving flame retardant effect. However, halogen flame retardants may produce toxic gases and corrosive substances when burning. Phosphorus-based flame retardants form substances such as phosphoric acid during combustion, which can form a protective film on the surface of the material to isolate oxygen and prevent the further development of combustion.

Coating material of adhesive tape

Flame retardant components of coating: Some high-temperature tapes will have coatings on their surfaces, and the flame retardant properties of coating materials are also very important for the flame retardant effect of the whole tape. For example, coatings containing inorganic flame retardants (such as aluminum hydroxide and magnesium hydroxide) will absorb a lot of heat and release water vapor during combustion, thus reducing the flame temperature and playing a flame retardant role. At the same time, some organic coatings contain nitrogen-phosphorus synergistic flame retardant components, which can produce an expandable carbon layer when burning, which can effectively isolate oxygen and heat and prevent the spread of flame.

Thickness and uniformity of coating: Sufficient and uniform thickness of coating is the key to ensure flame retardant effect. If the coating is too thin, it may not form an effective flame retardant barrier during combustion; If the coating is uneven, the flame may break through from the thin coating, causing the tape to burn. For example, in the production process, through accurate coating process, the flame retardant coating is evenly distributed on the surface of the tape, and the thickness meets the design requirements, so as to ensure that the tape has good flame retardant performance.

Influence of manufacturing process

Processing temperature and pressure: In the manufacturing process of high-temperature adhesive tape, processing temperature and pressure will affect the crystallinity and molecular arrangement of adhesive tape materials. For example, for the adhesive tape containing crystalline polymer, too high processing temperature may lead to the decrease of crystallinity and thermal stability of the material, thus affecting the flame retardant performance. Proper pressure can make the internal structure of the material more compact and help to improve the flame retardant performance.

Drying and curing process: If the drying or curing process in the tape manufacturing process is insufficient, it may lead to residual solvents or incompletely reacted components in the tape. These residues may become combustion improvers when the adhesive tape burns, reducing the flame retardant performance of the adhesive tape. For example, after the flame retardant coating is applied, it needs to be cured at a suitable temperature and time, so that the resin in the coating can be fully crosslinked to form a stable flame retardant structure.

Use environmental factors

Temperature and humidity: High temperature environment will change the performance of adhesive tape materials. Under high temperature environment for a long time, some components of the adhesive tape may decompose, resulting in the decline of flame retardant performance. For example, some flame retardants may volatilize or decompose at high temperature and lose their flame retardant effect. Humidity will also affect the flame retardant performance of the tape. High humidity environment may make the adhesive tape absorb water, thus affecting its internal chemical structure and the distribution of flame retardant, and may not play a normal flame retardant role when burning.

Contact and reaction with other materials: In practical application scenarios such as new energy storage, high-temperature tape often contacts with other materials (such as battery electrolyte, metal shell, etc.). These materials may react chemically with the adhesive tape, thus affecting the flame retardant performance of the adhesive tape. For example, if the tape comes into contact with some electrolyte with strong oxidation, some components of the tape may be oxidized, changing its flame retardant structure and reducing its flame retardant performance.