PURPOSE: To obtain an image excellent in reproducibility for fine lines and resolution for printing of characters by using a surface-treated magnetic material, incorporating the magnetic material in a specified range of pts.wt. to polymerizable monomers, and incorporating a release agent in a specified range of pts.wt. to the monomer.
CONSTITUTION: This magnetic developer is directly obtd. by suspension polymn. of a monomer compsn. containing at least polymerizable monomers, magnetic material and release agent in a water-base medium. The magnetic material is incorporated by 20-70 pts.wt. calculated as untreated magnetic material to 100 pts.wt. of polymerizable monomers. Namely, if the amt. of the magnetic material is lower than 20 pts.wt., electrification characteristics decrease. If it exceeds 70 pts.wt., the amt. of the magnetic material is so large to decrease electricification property. The amt. of the release agent is 10-40 pts.wt. to 100 pts.wt. of polymerizable monomers. If the amt. of the release agent is lower than 10 pts.wt., the releasing effect of the toner decreases. If it exceeds 40 pts.wt., granulating property of the toner during production decreases and the obtd. toner shows deterioration of blocking property.
ISHIYAMA TAKAO
NAKAMURA TATSUYA
CHIBA TATSUHIKO
KASUYA TAKASHIGE
MATSUNAGA SATOSHI
