| abstract |
PROBLEM TO BE SOLVED: To provide a novel flat elliptical polymer particle. SOLUTION: It comprises a polymer of an unsaturated monomer containing as a main component at least one polymerizable monomer selected from a styrene compound and a (meth) acrylic acid ester not containing a reactive functional group. The flat elliptical polymer particles satisfying the following (1) to (4), wherein the front view, the plan view, and the side view of the projected view based on the law are all elliptical. (1) The average major axis (LAV) of the flat part is 0.13 ≦ LAV ≦ 500 μm, (2) The average minor axis (DAV) of the flat part is 0.1 ≦ DAV ≦ 250 μm, and (3) the major axis (L) is short. The average (P1AV) of the aspect ratio (L / D) calculated from the diameter (D) is 1.3 <P1AV ≦ 50, and (4) calculated from the minor diameter (D) and the thickness (T) of the side surface. The average aspect ratio (D / T) (P2AV) is 1.2 <P2AV ≦ 100. |