Self-Crosslinking Copolyester for Flame Retardancy Without Melt Dripping

The patent changes the chemical structure parameters of the polyester by incorporating monomers with specific functional groups (cyano, phenylacetylenyl, phenyl) that enable high-temperature self-crosslinking. This structural modification allows the material to form a crosslinked network at combustion temperatures, fundamentally changing the melt behavior from dripping to char formation, thus resolving the contradiction between flame retardancy and anti-dripping performance

The patent creates a composite functional system within the polyester chain by combining multiple structural units ([I] to [IV]) with different functions: basic polyester units, crosslinking functional units, and ionic units. This internal composite structure enables synergistic effects where crosslinking provides anti-dripping while ionic interactions enhance flame retardancy, eliminating the need for separate flame retardant additives that cause dripping

The patent converts the harmful combustion process into a beneficial protective process by designing monomers that undergo controlled crosslinking at high temperatures. Instead of allowing uncontrolled combustion that produces toxic halogen gases, the material self-crosslinks to form a protective char layer that prevents further combustion and eliminates toxic gas generation, turning the thermal energy that would cause harm into a protective mechanism

The patent replaces persistent halogen-based flame retardants with biodegradable natural monomers containing cyano, phenylacetylenyl, or phenyl groups. These monomers are incorporated into the polyester chain and provide flame retardancy through their crosslinking behavior, eliminating the environmental persistence and toxicity issues of halogen compounds while maintaining effective flame protection

The patent enables the polyester to self-regulate its melt behavior through built-in crosslinking functional groups that activate at high temperatures. During normal processing and use, the material maintains its original mechanical properties and spinnability. When exposed to combustion temperatures, the crosslinking mechanism automatically activates to prevent dripping, eliminating the need for external anti-dripping agents that would compromise mechanical performance

The patent transitions the anti-dripping mechanism from a spatial dimension (adding physical barriers like glass fibers) to a chemical dimension (molecular crosslinking). The crosslinking occurs at the molecular level within the polymer chain, creating a three-dimensional network that prevents melt flow without introducing foreign particles that would degrade mechanical properties or spinnability