Mita Industrial Co., Ltd.

Toshiro Tokuno

Nobuhiro Hirano

Hiroshi Shimoyama

Masami Tsujihiro

Tatsuo Imafuku

Hideki Ohta

Noriaki Tsubota

Masayoshi Okubo

Hideki Ota

Tsunetaka Matsumoto

Tomonori Wada

A toner composition is produced by bulk- or solution-polymerizing a fixer resin in the presence of toner-characteristic imparting agents such as a colorant and a charge controlling agent. According to this process, unlike a suspension polymerization method, since no surface-active agent is used at any stage of production, the produced toner is remarkably proof against moisture. Especially, if a grafted carbon black is used as the colorant, it is possible to obtain a toner in which the colorant is dispersed minutely and uniformly throughout the fixer resin.

Process for producing a toner for development of electrostatic charged

Spheroidal toner for developing electrostatic images is composed of a binding resin as its main component in which at least carbon black and a dispersion stabilizer for the carbon black are contained, the conductivity of the toner being in the range of 5.times.10.sup.-11 to 5.times.10.sup.-9 S/cm. The conductivity of the toner is preferably within the range of 4.times.10.sup.-10 to 5.times.10.sup.-9 S/cm. It is also desirable that the dispersion stabilizer be composed of at least one selected from the group consisting of oil-soluble dyes, coupling agents, and surfactants, and that according to Wadel's practical spheroidicity, the toner be within the range of 0.95 to 1.0. A method of manufacturing the toner includes the steps of: forming grafted carbon black by prepolymerization of a polymerizable composition containing carbon black and a monomer forming a binding resin; adding a carbon black dispersion stabilizer to the prepolymerized composition; and suspending the composition in an aqueous medium and polymerizing the suspended particles in the presence of a polymerization initiator.

Method of manufacturing a toner

Toner for developing electrostatic images contains at least a colorant and a charge control dye in a binding resin which is the main component thereof, the toner having a surface dye density of less than 5.times.10.sup.-3 g/g and containing a monomer having a charge control polar group within the range of 0.01 to 5 weight percent based on the weight of the toner. The binding resin is preferably formed from at least one kind of monomer selected from a group consisting of vinyl aromatic monomers, acrylic type monomers, vinyl ester type monomers, vinyl ether type monomers, diolefin type monomers and monoolefin type monomers, and further preferably from at least one kind of monomer selected from a group consisting of styrene, ester acrylate and ester methacrylate. Also, the binding resin may be formed from at least one kind of monomer selected from a group consisting of polyester, phenol and epoxy resins. It is desirable that the colorant be used in 0.1 to 50 parts by weight for every 100 parts by weight of the polymerizable monomer. A magnetic pigment may also be used in addition to or instead of the colorant. In this case, it is desirable that the magnetic pigment be used in 1 to 200 parts by weight, and preferably in 5 to 100 parts by weight, for every 100 parts by weight of the polymerizable monomer.

Toner for developing electrostatic images

Disclosed a process for the preparation of polymer particles, which comprises suspending a polymerizable monomer, a radical initiator and a hardly soluble inorganic dispersant in a dispersion medium and carrying out polymerization in this state, wherein a hardly soluble inorganic dispersant, the solubility of which is changed according to the pH value in the dispersion medium and which is precipitated at a pH value within a certain pH value region of the dispersion medium, is used as the dispersant, suspension of the polymerizable monomer in the dispersion medium is carried out in the state where the dispersant is dissolved in the dispersion medium, an acid or base is then added to adjust the pH value of the dispersion medium to a predetermined level to precipitate the dispersant, and the polymerization is initiated in the state where oil drops having a fine particulate size are formed. The process is effectively utilized for obtaining a toner having good flowability and blocking resistance and excellent developing and fixing properties by using a colorant together with the polymerizable monomer.

Process for preparation of polymer particles, process for preparation of

A process for producing an electrophotographic toner in one step by suspension polymerization of monomers capable of forming a fixing resin. In a first embodiment, the suspension polymerization is carried out in the presence of a specific suspension stabilizer and a radical polymerization initiator. In a second embodiment, the suspension polymerization is carried out while applying ultrasonic radiation of a fixed frequency. The process gives a toner having a uniform particle size distribution.

Processes for producing electrophotographic toner

Disclosed is a process in which a spherical electrophotographic toner containing a colorant and having a particle size suitable for the electrophotography is directly formed in the polymerization process for formation of a binder resin. If a reaction medium capable of dissolving a monomer but incapable of dissolving a formed polymer is used and polymerization is carried out in the presence of a radical polymerization initiator in the state where the monomer, the colorant and other additives are dissolved or dispersed in the reaction medium, an electrophotographic toner having a desired particle size is obtained. According to this process, the particle size of the colored resin is stably controlled to 1 to 30 .mu.m suitable for a toner in the polymerization process, and the particle size distribution is very sharp.

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Takarazuka, Japan

Toshiro Tokuno