PURPOSE: To produce a carrier possible to form an uniform continuous film on a magnetic core particle, less in the flocculation of the carrier and excellent in the maintainability of a copying image quality in high yield by specifying heating and cooling speed in the specific temp. region of softening point of the main component resin in a coating resin.
CONSTITUTION: By heating the core particle and the coating resin particle, which are dry mixed, to a temp. above the softening point of the binding resin, the resin is melted and softened and forms the continuous coating layer on the surface by the spreading working and the carrier is produced by cooling to a temp. below the softening point of the resin while continuing furthermore mixing them to prevent the flocculating and solidifying of the carrier with each other. In this case, by making heating and cooling speed ≥1°C/min in the region of ±10°C of the softening point of the main component of the resin, the continuous film is formed when using one kind of coating resin, and a matrix with the resin jointly used is made when using two or more kind of coating resin and the coating film finally formed is the uniform continuous film.
MATSUMURA YASUO
KIMURA TSUTOMU
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