Expanding microspheres
Microsphere foaming agents are a type of hollow polymer microspheres consisting of a low-boiling-point hydrocarbon core encapsulated by a thermoplastic shell, typically ranging in diameter from 5 to 50 micrometers. Upon heating, the core vaporizes while the shell softens and expands, resulting in a volume increase of 3 to 8 times the original size. This entire process occurs without generating any gaseous by-products, representing a purely physical foaming mechanism. The controllable, clean, and low-temperature responsive expansion characteristics of these microspheres make them widely used in inks, coatings, plastics, simulated leather, and high-end composite materials, achieving multiple functions such as weight reduction, thermal insulation, cushioning, and surface texture control.