Fujikura Kasei Co., Ltd.

Yutaka Kukimoto

Hikoji Ueda

Masao Watanabe

Kozo Suzuki

Takayuki Ishimoto

Masamitsu Mogi

Shinji Yatabe

Yoshihiko Koshiyama

A negative charge controlling agent, wherein: the negative charge controlling agent comprises polycondensation product obtained by a polycondensation reaction of phenols and aldehydes; and the phenols comprises a (A) mononucleus phenolic compound which has one phenolic hydroxy group in which a hydrogen is bonded at the ortho position of a hydroxyl group of the phenolic hydroxy group and a (B) multinucleus phenolic compound which has at least two phenolic hydroxy groups in which a hydrogen is bonded at the ortho position of a hydroxyl group of each of the phenolic hydroxy group; and the content of the (B) phenolic compound in the phenols is 1 to 30 mol %.

Negative charge controlling agent and static charge image developing toner using the same, and method for producing the same

The method of decreasing unreacted monomer in vinyl polymer of the present invention is a method comprising adding a water-soluble inorganic salt that is able to solubilize unreacted monomer contained in vinyl polymer to an aqueous dispersion in which particles of vinyl polymer are dispersed in an aqueous medium, followed by solubilizing the unreacted monomer and removing the unreacted monomer together with the aqueous medium. According to this method, the amount of unreacted monomer present in a polymer can be efficiently and reliably decreased at low cost without requiring a special apparatus or thermal energy, etc. In addition, the toner resin of the present invention has for its constituent component a vinyl polymer in which the amount of unreacted monomer has been decreased by the method described above. In addition to solving the problem of a foul odor being generated during toner production and fixation when copying, the vinyl polymer obtained according to the method of the present invention also has superior effects such as contributing to improvement of toner characteristics.

Method of decreasing unreacted monomer in vinyl polymer and a toner resin in which unreacted monomer has been decreased

A process for producing a composite resin for a toner, comprising the steps of: mixing, in water, (a) a low-molecular weight polymer powder comprising particles, not less than 80% by weight of the particles having a diameter of from 20 to 2000 microns with (b) a high-molecular weight polymer emulsion; subjecting the thus obtained mixture to a coagulation treatment; and heating the resulting mixture to obtain a composite resin in which the low-molecular weight polymer particle and the high-molecular weight polymer are fixed and homogeneously mixed with each other.

Process for producing composite resin for toner

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Tokyo, Japan

Yutaka Kukimoto