Views:1 Author:Site Editor Publish Time: 2021-04-30 Origin:Site
Nonwovens are finding more and more applications requiring flame retardancy in areas that were once the sole domain of woven textiles; Nonwoven products are mainly manufactured using synthetic fibers such as polyolefin, polyester or nylon that represent highly flammable products. Polypropylene, in particular, burns very rapidly with a relatively low amount of smoke and without leaving a char residue because of its wholly aliphatic hydrocarbon structure. Its self ignition temperature is around 570 C and it presents a rapid decomposition rate compared with wood and other cellulosic materials.
Flame retardancy of nonwovens can be achieved in two ways: additive (mechanically blending the FR chemistry with the polymer prior to extrusion) and topical (coating the fiber or fabric with the FR chemistry). Additive types are useful with thermoplastics, while topical treatments can be used with thermoplastics, thermosets and natural fibers.
What are Flame Retardants and how do they Work?
There are several stages in the combustion process: heating, decomposition, ignition, flame spread and smoke generation. The combustion leads to the production of heat that is fed back and pyrolyzes the polymer, produces more fuel, and keeps the combustion process going. Flame retardants are chemicals that interfere in one or several of the steps in the combustion process. This is done in four distinct modes of action:
1. Reaction in the gas phase,
2. Reaction in the condensed phase,
3. Cooling effect and
4. Dilution effect.
A flame-retardant additive for nonwovens must meet the following requirements:
The product must not adversely affect the natural color or coloration of the fiber.
It must be non-smoking during fiber production.
It must have no adverse effects on short- and long-term fiber properties.
It must have no adverse effect on ultraviolet (UV) durability.