Principle of Flame Retardancy in Conveyor Belts

Conveyor belts are widely used across various industries. However, in specific sectors or environments, standard conveyor belts may not be suitable for material transportation. In these cases, specialized conveyor belts, such as flame retardant conveyor belts, are required. So, what is the principle behind the flame retardancy of conveyor belts, and how do they achieve this effect?

Generally, conveyor belts are made from natural rubber and styrene-butadiene rubber, which are materials that are highly flammable. Therefore, to create flame-retardant conveyor belts, flame retardants must be added during production to prevent combustion.

Flame-retardant conveyor belts are produced using a bonding method, incorporating a flame-retardant system made from antimony trioxide, chlorinated paraffin, zinc borate, and aluminum hydroxide. These materials act in the following ways:

1. Antimony Trioxide:
   Antimony trioxide is a flame retardant that by itself does not possess flame-retardant properties but becomes highly effective when combined with chlorinated compounds. When the material burns, antimony trioxide reacts with the chlorinated compounds on the surface layer of the flammable material to form volatile antimony chloride and antimony oxychloride. These volatiles absorb heat, and the gases they release can block oxygen and dilute flammable substances, thus slowing down or even stopping the combustion process.

2. Chlorinated Paraffin:
   Chlorinated paraffin is also a flame retardant. When exposed to high temperatures, chlorinated paraffin decomposes to release chlorine atoms. These chlorine atoms then react with the polymer (rubber, nylon, fabric, etc.), producing hydrogen chloride gas. This hydrogen chloride then reacts with high-activity hydroxyl radicals or hydrogen atoms, forming water or hydrogen gas, which interrupts the chain oxidation process, thereby slowing or halting the combustion. Adding flame retardants and carbon black helps achieve the required non-combustible properties.

Reasons for Rubber Peeling on Flame Retardant Conveyor Belts

During the use of flame-retardant conveyor belts, peeling of the surface layer may occur, which is often due to poor adhesion between the cover layer and the core. The main reasons for weak adhesion are as follows:

1. Contamination During Fabrication:
   The core paste may pick up impurities when it passes over the guide rollers, reducing its bonding strength.

2. Inadequate Plasticization:
   If the core paste does not properly plasticize, it may fail to bond well with the surface paste.

3. Exudation of Plasticizers:
   If plasticizers in the core paste separate out, they can reduce the adhesion strength between the core and the cover.

If peeling becomes severe, it can significantly impact the performance and lifespan of the conveyor belt, which, in turn, will affect the efficiency of production processes. Therefore, operators should be well-versed in how to operate the conveyor system, as well as in identifying and maintaining the quality of the flame-retardant conveyor belts. Problems should be addressed promptly to prevent further damage.

Additionally, when selecting flame-retardant conveyor belts, it is crucial to verify their quality and ensure that they meet the necessary standards. This is a fundamental prerequisite for ensuring safe production practices.