The intumescent flame retardants used for polyester fabrics primarily consist of phosphorus and nitrogen elements. When exposed to heat, these agents generate a uniform carbonaceous foam layer on the fabric surface; this layer acts as a thermal barrier, blocks oxygen, suppresses smoke, and prevents the phenomenon of molten dripping, thereby imparting excellent flame retardant properties. Studies have demonstrated that polyester fibers treated with intumescent flame retardants exhibit superior flame retardancy and resistance to molten dripping. Although intumescent flame retardants have been extensively researched for applications in plastics, rubber, and synthetic polymers, their application in the flame retardant finishing of polyester fabrics remains relatively limited.
The FR polyester fabrics is primarily achieved through two methods: flame retardant modification of the original fibers during spinning, or surface modification treatments applied to the woven fabric. Fabric flame retardant finishing-classified as a surface modification technique-offers distinct advantages, such as process simplicity and low cost. Among the various agents used, phosphorus-containing flame retardants are particularly favored in polyester applications due to their low toxicity and high efficiency. Phosphorus-based flame retardants function primarily by promoting the carbonization of the polymer substrate, thereby exerting their flame retardant effect within the condensed phase.
A traditional intumescent flame retardant system typically comprises three components: an acid source, a carbon source, and a gas source. The acid source initiates the process by releasing inorganic acids-such as phosphoric acid or pyrophosphoric acid-which act as dehydrating agents; these acids undergo esterification reactions with polyols, causing the entire system to melt. Simultaneously, the gas source generates non-combustible gases and water vapor, causing the molten system to foam and expand. Under the influence of the dehydrating agents, the carbon source undergoes further dehydration and carbonization, generating inorganic residues and char; this process drives the melting and expansion of the entire system, ultimately forming a protective carbonaceous foam layer.
Polyester fibers are characterized by high tensile strength, as well as excellent heat resistance and chemical stability; consequently, they are widely utilized in home textiles and various interior furnishing fabrics. However, polyester is prone to melting when exposed to heat, posing a significant fire hazard. Therefore, research into flame retardant technologies for polyester textiles-and the subsequent development of flame retardant polyester products-is of paramount importance.
This study employs an intumescent system formulated from phosphorus-containing flame retardants and nitrogen-containing flame retardants (which generate non-combustible gases). Through the application of an appropriate post-treatment process, the resulting polyester fabrics demonstrate excellent flame retardant properties while retaining a desirable tactile feel and exhibiting only a minimal reduction in breaking strength.