Patent ID: 7943695

Claim:
A magnetic polymer particle, comprising: a magnetic powder; a crosslinked polymer formed by polymerization of an ethylenically unsaturated monomer; and a non-crosslinked polymer, the amount of the magnetic powder with respect to the total amount of the magnetic polymer particle being in a range of about 2.5% by mass to about 50% by mass, the ethylenically unsaturated monomer including a monomer having a hydroxyl group and a hydrophobic monomer which is free from a hydroxyl group, and the amount of hydroxyl groups included in the crosslinked polymer and the non-crosslinked polymer being in a range of about 0.1 mmol/g to about 5.0 mmol/g with respect to the total amount of the crosslinked polymer and the non-crosslinked polymer, the amount of the crosslinked polymer is in a range of about 0.5% by mass to about 49.5% by mass with respect to the total amount of the crosslinked polymer and the non-crosslinked polymer wherein the ethylenically unsaturated monomer further includes a monomer having a carboxyl group, the hydrophobic monomer which is free from hydroxyl group is further free from a carboxyl group.