Dainippon Ink and Chemicals, Incorporated

Toyomi Hashizume

Takashi Ito

Hitoshi Takayanagi

Minoru Nomura

Kenichi Hirabayashi

Yukiko Soma

Kazuo Itoya

Toshiro Kogawara

Hiroyuki Ohminato

Shoji Okuno

A toner for electrostatic image development made of a polyester resin having a spherical or generally spherical shape, which allows the use of a so-called oilless fixation system capable of fixing, without employing an anti-offset solution as a heat roller fixation system, and which also provides a developed image having excellent quality. The toner comprises a binder resin and a colorant. The flow beginning temperature Tfb of the toner is 90&deg; C. or higher and 120&deg; C. or lower, the T1/2 temperature exceeds 120&deg; C. and is 160&deg; C. or lower, and the flow ending temperature T end is 130&deg; C. or higher and 170&deg; C. or lower. The toner has a spherical or generally spherical shape having an average roundness of 0.97 or more. The toner can be produced by phase inversion at a low shear within a range of 0.2-5 m/second employing an added alcohol solvent.

Toner for electrostatic image development and method of producing the same

The present invention provides a polyester resin toner which has good fixing properties and is superior in image quality in a heat roller fixation system without employing an anti-offset solution, and which has a spherical or generally spherical shape and has a small particle diameter, and a method of producing the same. In a toner for electrostatic image development comprising a binder resin and a colorant, said binder resin is made of a polyester resin. Furthermore, the weight-average molecular weight as measured by gel permeation chromatography of a tetrahydrofuran-soluble fraction of said polyester resin contained in the toner is 30,000 or more and the weight-average molecular weight/number-average molecular weight is 12 or more and, moreover, the area ratio of a molecular weight of 600,000 or more is 0.5% or more and the area ratio of a molecular weight of 10,000 or less is within a range of 20-80%. The toner for electrostatic image development has a spherical or generally spherical shape having the average circularity (average value of circularity defined by (perimeter of a circle having the same area as that of a projected area of particles)/(perimeter of a projected image of particles)) of 0.97 or more.

Toner for electrostatic image development

An electrophotographic toner having a volume-average particle diameter of from 3 to 15 .mu.m. The toner comprises a spherical particulate material having an average circularity of not less than 0.97 having a colorant encapsulated in a binder resin. The binder resin is a styrene-acrylic resin having an acid value of from 30 to 150 which is at least partly crosslinked. The tetrahydrofuran insoluble content in the whole of the binder resin including crosslinkd portions in the particulate material is from 0.5 to 70% by weight.

Electrophotographic toner and process for the preparation thereof

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Ichihara, Japan

Toyomi Hashizume