Toyo Ink Mfg. Co., Ltd.

Toyo Ink Manufacturing Company

Toshiyuki Uemura

Tsukasa Iguchi

Tadashi Ogawa

Kazuhiro Jonai

Toshio Enokida

Michiko Tamano

Seiji Aida

Akimitsu Mochizuki

Sunao Satake

Yasuharu Iida

Toshikazu Onikubo

Hisashi Uraki

Mikiya Kato

Yoshiyuki Sakai

Jun Kaneda

Eriko Suzuki

Takashi Negishi

A method of producing microcapsules having an electrophoretic particle dispersion encapsulated comprises the steps of: emulsifying and dispersing a hydrophobic dispersion having electrophoretic particles dispersed in a hydrophobic medium by using a high-speed rotating stirring apparatus wherein the circumferential speed at the end of a stirring part is 2 m/s to 90 m/s, and the distance (a) between the end of the stirring part and that immobile part of the stirring apparatus which is nearest to the end of the stirring part is 0 mm&#x3c;(a)&#x3c;20 mm; and forming microcapsules of the emulsified and dispersed hydrophobic dispersion under stirring with a stirring blade.

Process for producing microcapsule enclosing electrophoretic particle dispersion, microcapsule enclosing electrophoretic particle dispersion and reversible display medium containing the same

A water-based pigment dispersion comprising 100 parts by weight of a pigment, 3 to 30 parts by weight of a sulfonic acid group-containing pigment derivative and water, wherein the sulfonic acid group-containing pigment derivative has only one sulfonic acid group in a molecule of a pigment of which the type is the same as the type of the pigment to be dispersed, the sulfonic acid group forms at least one salt selected from the group consisting of ammonia salt, an organic amine salt and a salt in which at least 15% of the sulfonic acid group is liberated and the rest is a salt with monovalent metal, the content of metal ion having a valence of at least 2 in a solid matter of the above water-based pigment dispersion is 500 ppm or less, and the above pigment is dispersed in water according to electrostatic repulsion due to the sulfonic acid group-containing pigment derivative adsorbed on the particle surface of the pigment, an inkjet recording liquid containing the same and process for the production thereof.

Water-based pigment dispersion, use thereof and process for the production thereof

There is disclosed a self-dispersible aqueous pigment dispersion and preparing method thereof, the dispersion comprising an aqueous solution, particles of a pigment and a water-soluble pigment derivative, said particles being dispersed in the aqueous pigment dispersion in a concentration within the range from 2 to 25 wt. % based on the amount of the aqueous pigment dispersion, wherein a part of the water-soluble pigment derivative is adsorbed on the surface of the particles of the pigment to form dispersed particles comprising the particles of the pigment adsorbed by said part of the pigment derivative, and the remaining parts of the water-soluble pigment derivative are free in the dispersion without being adsorbed on the surface of the pigment in a concentration less than the critical flocculation concentration on which flocculation is initiated on said particles of the pigment dispersed under said concentration. The pigment dispersion has high dispersibility in an aqueous system and excellent dispersion stability over time, and is applicable to an inkjet recording liquid, which provides excellent light-resistance, water-resistance and hue of printed image, and simultaneously reveals excellent discharge stability at the nozzles of ink-jet printer.

Self-dispersible aqueous pigment dispersion

A surface-treated organic pigment excellent in initial dispersibility and long-term dispersion stability in water and an organic solvent and free from the coagulation of pigment particles, obtained by reacting a sulfonating agent with an organic pigment dispersed in a solvent in which the organic pigment is insoluble or sparingly soluble, and thereby introducing a sulfonic acid group to the surface of each particle of the organic pigment.

Surface-treated organic pigment and process for the production thereof

Hole-transporting materials of the following formula (1) have excellent hole-transporting capability and excellent durability,

Hole-transporting material and use thereof

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Tokyo, Japan

Toshiyuki Uemura