Nippon Zeon Company, Ltd.

Tokudai Ogawa

Jun Hasegawa

Jun Sakai

Noboru Yanagida

Takahiro Takasaki

Kazuhiro Sato

Makoto Watanabe

Jun Saito

Kazunori Shigemori

Nobuyasu Ota

Fumio Yamada

Toyoko Imai

A monomer for a shell or a mixture of at least two monomers for a shell was suspension polymerized in the presence of core particles and a polymerization initiator to obtain polymer particles, wherein said core particles are formed of a polymer obtained by polymerization of a monomer for a core or a mixture of at least two monomers for a core and containing a colorant, wherein said monomer for a shell or mixture of monomers for a shell is one which gives upon polymerization a polymer having a glass transition temperature higher than that of the polymer forming the core particle, and wherein said polymerization initiator is represented by the following formula 1: ##STR1## wherein X.sup.1, X.sup.2, X.sup.3 and X.sup.4 independently represent oxygen atom, sulfur atom, &gt;NR (wherein R is hydrogen atom, alkyl group, or group); R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently represent alkyl group, aryl group, or alkyl or aryl group having at least one substituent which is --OR, --OH, --NHR, or --NR.sub.2 (wherein R is alkyl group or aryl group), and n and m independently represent an integer of 1 to 10. An outer additive was applied on the polymer particle to obtain a polymerized toner. This polymerized toner has low fixing temperature, excellent overhead projector transparency, good shelf stability, and exhibiting a less pronounced reduction in electric charge under conditions of high humidity and high temperature.

Polymerized toner

A polymerized toner of core-shell structure, comprising core particles composed of colored polymer particles, which comprise a polyfunctional ester compound formed of a trifunctional or still higher polyfunctional polyhydric alcohol and a carboxylic acid, and a colorant, and shell which is formed of a polymer having a glass transition temperature higher than that of a polymer component making up the core particles and covers each of the core particles, a production process thereof, an image forming process comprising using the polymerized toner, and an image forming apparatus containing the polymerized toner.

Polymerized toner and production process thereof

Disclosed herein are a polymerized toner of core-shell structure, comprising core particles composed of colored polymer particles having a volume average particle diameter (dv) of 0.5-20 .mu.m and a ratio (dv/dp) of the volume average particle diameter (dv) to a number average particle diameter (dp) of at most 1.7, and shell which is formed of a polymer layer having an average film thickness of 0.001-0.1 .mu.m and covers each of the core particles, and a production process thereof.

Process for producing polymerized toner

Production process of toner for development of electrostatic latent image

A process for producing a polymer toner comprises the steps of pouring a polymerizable monomer composition containing at least a polymerizable monomer and a colorant, but containing no oil-soluble polymerization initiator into an aqueous dispersion medium containing a dispersing agent; adding an oil-soluble polymerization initiator to the polymerizable monomer composition while stirring the composition to form primary droplets thereof, thereby bringing the droplets of the polymerizable monomer composition into contact with droplets of the oil-soluble polymerization initiator to form droplets of a polymerizable monomer composition containing the oil-soluble polymerization initiator; further continuing the stirring to form secondary droplets having desired droplet sizes; and then conducting suspension polymerization of the polymerizable monomer composition.

Process for producing polymer toner

A process for producing a toner for developing an electrostatic image, including the steps of: adding to an aqueous dispersion medium a polymerizable monomer composition comprising at least a polymerizable monomer and a colorant uniformly dissolved or dispersed in the polymerizable monomer, wherein the aqueous dispersion medium containing as a dispersion stabilizer a hardly water-soluble metal hydroxide colloid formed by a reaction of a water-soluble polyvalent metal salt with an alkali metal hydroxide in an aqueous phase; and subjecting the polymerizable monomer composition to suspension polymerization, thereby to produce particles having a volume-average particle size in the range of from 2 to 20 .mu.m and a particle size distribution (a ratio of volume-average particle size/number-average particle size) of not more than 1.6.

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Kanagawa, Japan

Tokudai Ogawa