POLYMER EXPANDED PARTICLE, EXPANDED TONER AND METHOD FOR PRODUCING POLYMER EXPANDED PARTICLE AND EXPANDED TONER

摘要

A polymer expanded particle and an expanded toner having small pores, and a production method thereof are provided. A polymer expanded particle comprises micropores having an average pore diameter of less than 50 μm. An expanded toner comprises micropores having an average pore diameter of 1 μm to less than 3 μm, wherein volume average particle diameter is 5 μm to less than 15 μm. A method for producing a polymer expanded particle comprises a first step for mixing specific polymer particles with high pressure gas or supercritical fluid, to prepare a mixture, a second step for impregnating with the high pressure gas or the supercritical fluid to the inside of the polymer particles, and a third step for reducing pressure and temperature of the mixture, to form the polymer expanded particle, wherein the pressure and temperature in the third step is reduced for 5 minutes or less from a state of 20 MPa or greater and 60° C. or greater to a state of less than 1 MPa and less than 30° C., respectively.