Flame-Retardant Hot Melt Adhesive Film

The heat released by combustion is limited. If part of the heat released by combustion can be absorbed in a short time, the flame temperature will decrease, radiating to the burning surface and acting on the heat that cracks the vaporized combustible molecules into free radicals. will be reduced, and the combustion reaction will be inhibited to a certain extent. For example, the flame retardant mechanism of Al(OH)3 flame retardant is to increase the heat capacity of the polymer, allowing it to absorb more heat before reaching the thermal decomposition temperature, thereby improving its flame retardant performance. This type of flame retardant exerts its characteristic of absorbing large amounts of heat when combined with water vapor, thereby improving its own flame retardant ability.

After adding flame retardants to combustible materials, the flame retardants can form a glassy or stable foam covering layer at high temperatures to isolate oxygen. It has the functions of heat insulation, oxygen isolation, and preventing flammable gases from escaping outward, thereby achieving flame retardancy. Purpose. For example, when organophosphorus flame retardants are heated, they can produce a cross-linked solid material or carbonized layer with a more stable structure. On the one hand, the formation of the carbonized layer can prevent further pyrolysis of the polymer, and on the other hand, it can prevent the thermal decomposition products inside it from entering the gas phase to participate in the combustion process.

According to the chain reaction theory of combustion, free radicals are needed to maintain combustion. Flame retardants can act on the gas phase combustion zone to capture free radicals in the combustion reaction, thereby preventing the spread of flames, reducing the flame density in the combustion zone, and reducing the combustion reaction speed until it is terminated. For example, the evaporation temperature of halogen-containing flame retardants is the same as or similar to the decomposition temperature of the polymer. When the polymer decomposes by heat, the flame retardant also volatilizes at the same time. At this time, the halogen-containing flame retardant and the thermal decomposition products are in the gas phase combustion zone at the same time, and the halogen can capture the free radicals in the combustion reaction and interfere with the combustion chain reaction.

Flame retardants decompose into non-combustible gases when heated, diluting the concentration of combustible gases decomposed from combustible materials below the lower combustion limit. At the same time, it also has a diluting effect on the oxygen concentration in the combustion zone, preventing the continuation of combustion and achieving a flame retardant effect.