Graft copolymer-containing solid product and use thereof

A core-shell type polymer solid product comprising a graft copolymer (C) having:

• a main chain portion derived from a precursor polymer (A);
• and a graft portion derived from a polymer (B) different from the polymer (A), wherein:
• a core portion (a) of the solid product comprises the main chain portion derived from the precursor polymer (A), and a shell portion (b) of the solid product comprises the graft portion derived from the polymer (B);
• and
• the core-shell type polymer solid product satisfies the following requirement (I):
• Requirement (I):
• In infrared absorption spectroscopic measurement of a section passing through a center (x) of the solid product, a point (z) on a surface where a distance between the center (x) and the surface is shortest, and a middle point (y) of a line connecting the center (x) and the point (z), absorbance (Abs) at the center (x), at the middle point (y), and at the point (z) satisfy the following relationship:
• X<0.01,
• Y<0.01, and
• Z≥0.01,
• wherein
• X represents a value of Abs (key band of polymer (B))/Abs (key band of polymer (A)) at the center (x),
• Y represents a value of Abs (key band of polymer (B))/Abs (key band of polymer (A)) at the middle point (y), and
• Z represents a value of Abs (key band of polymer (B))/Abs (key band of polymer (A)) at the point (z).