| 摘要 |
PURPOSE:To improve the durability, the negative chargeability and the moisture resistance by fusing fine particles charged negatively and have smaller particle size than the core particle on the core surface charged positively in an aqueous medium. CONSTITUTION:The core particle may be either a homopolymer of a monomer having a nitrogen atom in the molecule or a copolymer of the monomer with the other monomer not having an electric charge and the copolymer is preferred in the view point of imparting moisture resistance. Also the fine particles are composed of a homopolymer of a monomer having a sulfonic acid group in the molecule, the copolymer of the monomer with the other monomer or the polymer using a polymerization initiator of a persulfate salt imparting a negative charge. The core particles and the fine particles are mixed in an aqueous medium and the fine particles are fused on the surfaces of the core particles by heat treatment at a higher temp. than a glass transition temp. of the core particles. Namely, since the core particles and the fine particles have mutually opposite charges, when they are mixed, the fine particles stick electrically on the surfaces of the core particles. When they are fused by heat treatment in this condition, the adhesion becomes firm. |
