Nippon Zeon Company, Ltd.

Zeon Corporation

Toyo Tire Rubber Co., Ltd.

Shin-Etsu Polymer Co., Ltd.

Toyo Ink Manufacturing Company

Toyo Ink Sc Holdings Co., Ltd.

Toyo Ink Co., Ltd.

Yamanashi Electronics Co., Ltd.

Oriental Photo Industrial Co., Ltd.

Toyo Ink Mfg. Co., Ltd.

Kazunori Shigemori

Nobuyasu Ota

Jun Hasegawa

Kazuhiro Sato

Masahiro Sugihara

Daisuke Fujiwara

Satoshi Washio

Masahiro Ikeda

Jun Saito

Kenji Kagami

Seiji Aida

Atsushi Yoda

Mitsuo Umezawa

Tokudai Ogawa

Yukitoshi Takahashi

Masayoshi Utsugi

Ken Yamasaki

Atsushi Nakazato

Tomoharu Takeuchi

Yukio Takegawa

Yasushi Ariyoshi

Muneharu Ito

Fuminori Tsuruta

Sokuei Motoda

Ken Yamazaki

Hidetoshi Azuma

Katsuhiro Imai

Tomoko Tachibana

Katsuhiro Hasegawa

Kenichi Nishio

Natsuko Kokubo

Tsutomu Hiroshima

Joji Mikami

Toshiyuki Nagai

Yasutaka Itimura

Toshiro Murano

Hirosi Yamamoto

Yoshihiro Makuta

Ryuji Ota

Kouhei Yamada

Provided is an inkjet pigment ink which contains a pigment that is selected from the group consisting of C.L. Pigment Yellow 74 having a transmittance of 70% or more, C.I. Pigment Red 269 having a transmittance of 70% or more, C.I. Pigment Red 122 having a transmittance of less than 70% and C.I. Pigment Yellow 150; a water-soluble solvent that is selected from the group consisting of glycol ethers and diols; water; and a pigment dispersing resin that is a copolymer which contains a monomer A, a monomer B and a monomer C as unit components. The monomer A is an alkyl (meth)acrylate ester; the monomer B is styrene, &#x3b1;-methyl styrene or benzyl (meth)acrylate; and the monomer C is (meth)acrylic acid.

Inkjet pigment ink

A dispersing agent characterized in that said dispersing agent is prepared by reacting primary and/or secondary amino groups of an amine compound comprising a polyamine (C) with isocyanate groups of a urethane prepolymer (E) having two isocyanate groups in one terminal region, wherein said urethane prepolymer (E) has been prepared by reacting hydroxyl groups in a vinyl polymer (A) having two hydroxyl groups in one terminal region with isocyanate groups in diisocyanates (B), and in that an amine number of said dispersing agent is 1 to 100 mgKOH/g is disclosed. The dispersing agent of the present invention has excellent dispersibility, flowability, and storage stability when used in small quantities. A pigment-dispersed product can be prepared therefrom, independently of the kinds of binder resin or solvent used. Further, the present invention is suitable for offset ink, gravure ink, resist ink for a color filter, inkjet ink, coating composition, and colored resin composition.

Dispersing agent, and pigment composition, pigment-dispersed product and inkjet ink prepared therefrom

In an image forming method including a charging step, an exposure step, a development step using a developing roll, a transfer step, a fixing step and a cleaning step of removing a toner remaining on the surface of a photosensitive member after the transfer step, the developing roll has a surface brightness of 30 to 220 and a surface roughness Rz of 1 to 20 &#x3bc;m, the cleaning blade is a cleaning blade made of a polyurethane elastomer and having a peak value of at most 0.95, a peak temperature of &#x2212;15 to 10&#xb0; C. and a width at half maximum of at least 25&#xb0; C. in viscoelasticity tan &#x3b4;, the toner has a volume average particle diameter of 4 to 10 &#x3bc;m and an average circularity from 0.950 to 0.995, the charge level of the toner on the surface of the photosensitive member is 10 to 80 &#x3bc;C/g in terms of an absolute value, and the pH of a water extract of the toner is 3 to 8.

Image forming method

A method of producing a toner having a process of mixing colored particles and outer-additives by using a mixer with an agitating blade whose shaft portion is sealed with a gas having a flow rate of from 0.4 m /hr to 3 m /hr and which rotates at such a high speed as a peripheral speed at a tip of said agitating blade in a range of from 20 m/sec to 50 m/sec. When the colored particles and outer-additives are mixed with each other, there is no generation of aggregates thereby and the toner can be obtained at a high yield. Therefore the toner which hardly generates a white streak and fog, even after a long period of continuous operation of development of electrophotographs is performed, can be obtained.

Method for producing toner by mixing colored particles and outer-additive by mixer with stirrer of high speed rotation

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

The invention provides a developer comprising toner particles and a finely particulate polymer, wherein the finely particulate polymer is a finely particulate polymer of core-shell structure, which has a core part formed of a vinyl aromatic hydrocarbon polymer and a shell part formed of a (meth)acrylic ester polymer, and is obtained by a soap-free emulsion polymerization process. The developer has stable flowability and charging properties. The invention also provides such a finely particulate polymer and a preparation process thereof.

Developer and finely particulate polymer

A non-magnetic one-component developer comprises a binder resin and a colorant, and has a volume-average particle diameter (dv) in a range of 5-15 .mu.m, a ratio (dv/dn) of the volume-average particle diameter (dv) to the number-average particle diameter (dn) in a range of 1.00-1.40, a quotient (Sc/Sr) obtained by dividing the area (Sc) of a circle supposing the absolute maximum length of a particle is a diameter by the real projected area (Sr) of the particle in a range of 1.00-1.30, a product (AxdnxD) of the specific surface area (A) (m.sup.2 /g) as measured in accordance with the BET method, the number-average particle diameter (dn) (.mu.m) and the true specific gravity (D) in a range of 5-10, and a ratio (Q/A) of the charge level (Q) (.mu.c/g) to the specific surface area (A) in a range of 80-150. The developer is substantially spherical from both conditions of Sc/Sr and AxdnxD, and is suitable for use in a development process in which cleaning is conducted at the same time as development. A development process making use of the non-magnetic one-component developer is also disclosed.

Non-magnetic one-component developer and development process

A process for producing a heat-developable photosensitive material containing fine photosensitive silver halide particles having a uniform particle form and particle size, said silver halide being prepared by reacting a silver salt of an organic fatty acid stoichiometrically with an inorganic or organic halogen compound.

Process for producing a heat-developable photosensitive material

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Tokyo, Japan

Kazunori Shigemori