Mita Industrial Co., Ltd.

Kyocera Mita Corporation

Hiroshi Shimoyama

Toyotsune Inoue

Nobuhiro Hirano

Toshiro Tokuno

Takayuki Itakura

Masami Tsujihiro

Yoshitake Shimizu

Kenshi Matsui

Kazuya Nagao

Tatsuo Imafuku

Takahiro Ishihara

Norio Horikami

Hideki Ohta

Takashi Nishino

Yoshio Sugishima

Keiji Okumura

Naruo Yabe

Sadahiro Matsuura

Kazuhisa Kondoh

Toshiro Okae

Hideki Ota

Takuya Kadota

Tomonori Wada

Tohru Tanjyoh

Tadakazu Okitsu

A sheet post-processing apparatus having a sheet tray, a sheet transportation path for guiding a sheet into the sheet tray, a bypass path bypassing a part of the sheet transportation path for guiding a sheet into the sheet tray, a post-processing mechanism for performing a post-processing operation on one set of sheets retained in the sheet tray, and a sheet transportation mechanism for feeding the sheet into the sheet tray. During the post-processing operation performed on the one set of sheets previously fed into the sheet tray, the first sheet of the next sheet set is once stopped in one of the transportation path and the bypass path, and the second sheet of the next sheet set is introduced into the other of the bypass path and the transportation path. Upon completion of the post-processing operation performed on the one sheet set, the first and second sheets of the next sheet set are fed into the sheet tray.

Sheet post-processing apparatus

Disclosed are a positive charging color toner comprising a coloring agent and a positive charging electric charge controlling material in a fixing resin, wherein the fixing rein is an urethane-modified polyester resin having an acid value of not more than 5 KOHmg/g, a hydroxyl value of not more than 9 KOHmg/g, a weight-average molecular weight of 8,000 to 120,000 and a number-average molecular weight of 2,000 to 70,000, and the positive charging electric charge controlling material is (a) a quaternary ammonium salt having a melting point of not less than 200&deg; C., or (b) a styrene-acrylate copolymer having a trisubstituted amminio group and a glass transition temperature Tg of not less than 55&deg; C.; and a positive charging one-component non-magnetic color toner comprising a polyester resin having an acid value of not more than 5 KOHmg/g, a hydroxyl value of not more than 9 KOHmg/g, a weight-average molecular weight of 7000 to 20,000 and a number-average molecular weight of 1,000 to 6,000, a polyolefine (releasing agent) having an acid value of not more than 10 KOHmg/g and a weight-average molecular weight of 8,000 to 15,000, a proportion of a polyolefine having a particle diameter of not less than 1.5 &mgr;m among polyolefines dispersed in the toner being within 1% in terms of the number, a coloring agent and a positive charging electric charge controlling resin.

Positive charging color toner

Disclosed are a positive charging color toner comprising a coloring agent and a positive charging electric charge controlling material in a fixing resin, wherein the fixing rein is an urethane-modified polyester resin having an acid value of not more than 5 KOHmg/g, a hydroxyl value of not more than 9 KOHmg/g, a weight-average molecular weight of 8,000 to 120,000 and a number-average molecular weight of 2,000 to 70,000, and the positive charging electric charge controlling material is (a) a quaternary ammonium salt having a melting point of not less than 200.degree. C., or (b) a styrene-acrylate copolymer having a trisubstituted amminio group and a glass transition temperature Tg of not less than 55.degree. C.; and a positive charging one-component non-magnetic color toner comprising a polyester resin having an acid value of not more than 5 KOHmg/g, a hydroxyl value of not more than 9 KOHmg/g, a weight-average molecular weight of 7000 to 20,000 and a number-average molecular weight of 1,000 to 6,000, a polyolefine (releasing agent) having an acid value of not more than 10 KOHmg/g and a weight-average molecular weight of 8,000 to 15,000, a proportion of a polyolefine having a particle diameter of not less than 1.5 .mu.m among polyolefines dispersed in the toner being within 1% in terms of the number, a coloring agent and a positive charging electric charge controlling resin.

A two-component binder-type magnetic carrier for developing agent comprising a magnetic powder and a binder resin. The carrier particles contain dispersed therein a release agent of the type of a metal soap and have abrasive or collapsible surfaces. By using the developing agent which contains this carrier, the magnetic powder peels off the carrier particle surfaces maintaining a controlled particle diameter and amount. Therefore, the carrier particles possess fresh surfaces at all times, whereby the occurrence of spent toner is effectively prevented and the charging amount of the toner is stably maintained.

Magnetic carrier for electrophotographic developing agent

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

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Osaka, Japan

Hiroshi Shimoyama