| abstract |
The present invention provides a method for producing elliptical, needle-shaped or rod-shaped polymer particles satisfying the following (1) to (3), which comprises the step of mixing a mixed solvent containing water, a hydrophilic organic solvent and a hydrophobic organic solvent , the synthesis solution of the polymer stabilizer, the polymerization initiator and the unsaturated monomer is heated, and the pH of the synthesis solution is adjusted to 5 or lower or 9 or higher at least after the start of heating to perform solution polymerization. (1) The average value (L AV ) of the long axis (L) of the projected two-dimensional image obtained by irradiating light from a direction orthogonal to the long axis direction is 0.1 to 80 μm, and (2) from the direction orthogonal to the long axis direction The average value (D AV ) of the short axis (D) of the projected two-dimensional image obtained by irradiating light in the direction is 0.05 to 40 μm, and (3) the aspect ratio ( The average value (P AV ) of L/D) was 1.5 to 30. |