Kao Corporation

Yutaka Murai

Manabu Suzuki

Nobumichi Kamiyoshi

Hiroshi Mizuhata

Hiromi Nambu

The present invention relates to a toner for electrophotography which has a small particle size and is excellent in all of low-temperature fusing ability, anti-hot offset property and image characteristics and a process for producing the toner, as well as to a dispersion of crosslinked resin particles which is used for production of the toner for electrophotography and a process for producing the dispersion of crosslinked resin particles. The dispersion of crosslinked resin particles having a volume median particle size (D) of from 0.05 to 0.7 &#x3bc;m according to the present invention is produced by a process including the steps of (A) neutralizing a resin containing an acid group-containing polyester in an aqueous medium to obtain a dispersion of resin particles; and (B) mixing the dispersion of resin particles obtained in the step (A) with an oxazoline group-containing polymer at a temperature of from 60 to 100&#xb0; C.

Crosslinked resin particle dispersion liquid

The present invention relates to a toner for electrophotography which exhibits an excellent heat-resistant storage property and a wide fusing temperature range, and a process for producing the toner for electrophotography. There are provided a process for producing a toner for electrophotography which includes (A) a step of emulsifying a resin binder containing a polyester having a constitutional unit derived from a trivalent or higher-valent carboxylic acid in an aqueous medium; (B) a step of aggregating emulsified particles contained in an emulsion obtained in the step (A); and (C) a step of coalescing aggregated particles obtained in the step (B), said process further including the following steps which are to be conducted after the step (A): (a) a step of adding a compound having at least one functional group selected from the group consisting of an oxazoline group and a glycidyl group; and (b) a step of forming a chemical bond between the compound having the at least one functional group and the resin binder containing the polyester, as well as a toner for electrophotography obtained by the process.

Process for producing toner for electrophotography

The present invention relates to a process for producing a toner for electrophotography which includes the steps of (A) forming resin-containing core particles having a volume median particle size (D50) of from 1 to 10 &#x3bc;m in an aqueous medium; (B) adding composite fine particles containing a polyester-containing resin and a charge control agent, or composite fine particles containing 'fine particles of the charge control agent' and 'fine particles of the polyester-containing resin', to the core particles obtained in the step (A) to allow the composite fine particles to adhere onto the core particles, thereby obtaining &#x201c;composite fine particle-adhering core particles&#x201d;; and (C) heating the &#x201c;composite fine particle-adhering core particles&#x201d; obtained in the step (B), to obtain coalesced particles. There are provided a process for producing a toner for electrophotography having a small particle size and a narrow particle size distribution which is capable of allowing a charge control agent to exist on a surface of the toner; and a toner for electrophotography which is produced by the process and can exhibit excellent image-forming characteristics.

The present invention relates to a process for producing a toner for electrophotography, including:

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Wakayama, Japan

Yutaka Murai