Application of Flame-Retardant Double-Layered Shell Microcapsules to Nonwoven Polyester

Area of Science:

• Materials Science
• Polymer Chemistry
• Textile Engineering

Background:

• Development of flame retardant materials is crucial for safety in various applications.
• Microencapsulation offers a method to incorporate active substances into textiles without compromising properties.
• Resorcinol bis(diphenyl phosphate) is an effective flame retardant core material.

Purpose of the Study:

• To create a flame retardant nonwoven substrate using microencapsulated flame retardants.
• To investigate the effect of different thermoplastic outer shells (polystyrene and poly(methyl methacrylate)) on microcapsule properties and performance.
• To evaluate the thermal stability and flame retardancy of the modified nonwoven substrate.

Main Methods:

• Microencapsulation of resorcinol bis(diphenyl phosphate) within melamine-formaldehyde shells, coated with polystyrene or poly(methyl methacrylate).
• Impregnation of a bi-component PET/co-PET spunbond nonwoven substrate with the microcapsules.
• Thermal analysis using thermogravimetric analysis (TGA).
• Microstructural observation using scanning electron microscopy (SEM).
• Flame retardancy testing according to the NF P92-504 standard.

Main Results:

• Microcapsule shell composition significantly influenced thermal stability; polystyrene shells yielded more stable particles.
• Microcapsules adhered well to the nonwoven surface via thermoplastic shell softening, without increasing substrate thickness.
• All tested formulations exhibited low flame spread rates.
• Formulations with low polystyrene content achieved M2 classification, while others were rated M3.

Conclusions:

• Microencapsulation with thermoplastic outer shells is a viable method for imparting flame retardancy to nonwoven textiles.
• Polystyrene outer shells enhance the thermal stability and flame retardant performance of the microcapsules.
• The choice of thermoplastic shell material and its content are critical factors in optimizing flame retardancy and material properties.