Analysis of the principle of fabric flame retardant

Flame retardant fabrics refer to fabrics that can prevent themselves from being ignited or delay and stop burning when they come into contact with flames or hot objects. The instrument for testing the flame retardancy of fabrics is the Fabric Flame Retardant Tester.

Theory of fabric flame retardant:

1. Covering theory: When the temperature of the flame retardant is > 500 ℃, an isolation cover can be formed on the surface of the fiber, which not only hinders the supply of O2, but also prevents the outward diffusion of combustible gas, so as to achieve the purpose of flame retardant, such as borax-boric acid.

2. Gas theory: one is that the flame retardant decomposes the non-combustible gas at the combustion temperature, and the concentration of the flammable gas is diluted below the concentration that can generate a flame; the other is that the flame retardant can be used as a highly active free radical transfer body under heating conditions. , thereby preventing free radical reactions.

3. Thermal theory: First, the flame retardant absorbs heat at high temperature, such as melting and sublimation, to prevent the spread of combustion; second, the fiber dissipates heat quickly, so that the fabric cannot reach the burning temperature.

4. Catalytic dehydration theory: mainly refers to changing the process of fiber thermal cracking. Because the flame retardant can quickly dehydrate the cellulose molecular chain before breaking, and even have some cross-linking effect, prevent the production of L-glucose, and inhibit the flame burning.

The flame retardant effect of organophosphorus compounds is to form esters with hydroxyl groups in fiber molecules, prevent the formation of L-glucose, further dehydrate, generate unsaturated double bonds, promote the cross-linking of fiber molecules, increase the formation of carbon, and have a good flame retardant effect. . Only when the amount of finishing agent is increased to 10%, the flame burning can be effectively prevented.

The principle of fabric combustion performance:

(1) The combustion phenomenon can be divided into flame combustion and flameless combustion. The former is the combustion of gases and volatile liquids formed when the fibers are thermally decomposed, and the latter is the oxidation of the residue (carbon).

(2) The combustion of fiber is related to its thermal decomposition products, and the thermal decomposition process of different fibers is also different.

The current fiber flame retardant can make full use of the flame retardant than the fabric flame retardant, and its effect is more durable and softer. However, in practical applications, a variety of flame retardants are often used to achieve the flame retardant effect in two or more ways. However, the cost of post-finishing flame retardant is much lower than that of fiber flame retardant.