Low-temperature thermal expansion microsphere and preparation method thereof

The invention provides a low-temperature thermal expansion microsphere and a preparation method thereof. The microspheres comprise a shell of thermoplastic resin and a core material encapsulated in the shell; wherein the shell of the thermoplastic resin is formed by polymerizing one or more of an acrylate-containing monomer, a carboxyl-containing monomer, a styrene-containing monomer, an acrylamide-containing monomer and a maleimide-containing monomer with a nitrile-containing monomer, vinylidene chloride and a cross-linking agent; preferably, the vinylidene chloride contains 50 to 3000 ppm of high-boiling residues; wherein the core material is low-boiling-point alkane. According to the microsphere, by controlling the space volume caused by the low-polymerization-activity or non-polymerization-activity high-boiling-point substance in the shell layer, the foaming agent leakage of the microsphere during expansion is reduced, the expansion rate is increased, and the burning explosion risk during expansion is red