Konica Minolta, Inc.

Sanyo Chemical Industries, Ltd.

Yuya Iwagoe

Chiaki Yamada

Masaaki Oka

Masahiro Anno

Naoki Yoshie

Mikihiko Sukeno

Satoshi Matsumoto

Nofumi Mizumoto

Masaru Honda

Shinichi Maeda

Masashi Minaki

Mitsumasa Kamura

Shuichi Shinohara

Provided is a toner binder having excellent charging characteristics and blocking resistance, and an increased range of fixing temperatures when used as a toner. The present invention is a toner binder containing a polyester resin (P) comprising one or more types of polyester resins obtained by polycondensation of a carboxylic acid component (x) and an alcohol component (y), wherein at least one type (P1) of (P) contains 50 to 95 mol % of a aliphatic diol (y1) having a carbon number of 2 to 4 in the alcohol component (y), and (P) satisfies expressions (1) and (2).11.5&#x2266;SP value [(cal/cm)] of ()&#x2266;13.0&#x2003;&#x2003;(1)5.2&#x2266;HLB value (by Oda method) of ()&#x2266;7.1&#x2003;&#x2003;(2).

Toner binder and toner

A liquid developer includes an insulating liquid and toner particles which are dispersed in the insulating liquid and contain a resin and a coloring agent. The resin contains a first resin which is a resin containing a component derived from a crystalline polyester resin. The coloring agent contains carbon black and nigrosine. The toner particles have a peak at not lower than 30&#xb0; C. and not higher than 50&#xb0; C. in a DSC curve in temperature decrease.

Liquid developer

A liquid developer includes an insulating liquid and toner particles which are dispersed in the insulating liquid and contain a resin and a coloring agent. The resin contains a first resin which is a crystalline urethane-modified polyester resin resulting from increase in chain length of a component derived from a polyester resin by a compound containing an isocyanate group. The toner particles have a peak in a DSC curve in temperature increase at 55&#xb0; C. or higher, have a peak in the DSC curve in temperature decrease at 30&#xb0; C. or higher, and have a storage elastic modulus at 80&#xb0; C., not lower than 1&#xd7;10Pa and not higher than 1&#xd7;10Pa.

A liquid developer is obtained by dispersing toner particles containing a core resin, a shell resin different from the core resin, and a coloring agent in an insulating liquid. The core resin contains a crystalline urethane-modified polyester resin. A solid content of the liquid developer corresponding to a portion of the liquid developer excluding the insulating liquid has a storage elastic modulus at 80&#xb0; C., not lower than 1&#xd7;10Pa and not higher than 5&#xd7;10Pa. A lowest temperature at the time when an absolute value of an amount of change in a logarithmic value (log(G')) of a storage elastic modulus (G&#x2032;) of the solid content of the liquid developer with respect to a temperature T (&#xb0; C.) (|&#x394; log(G&#x2032;)/&#x394;T|) satisfies an Equation (1) below is not lower than 45&#xb0; C.:|&#x394; log(&#x2032;)/&#x394;|&#x3e;0.1&#x2003;&#x2003;Equation (1).

Disclosed is a toner binder which has high storage stability and can achieve both of good low-temperature fixability and good hot offset resistance (a broadened fixing temperature range). Specifically disclosed is a toner binder comprising, as constituting units, a carboxylic acid component (x) and a polyol component (y), wherein the component (x) comprises two or more kinds of dicarboxylic acids (X1), selected from among aromatic dicarboxylic acids and ester-forming derivatives of the same, in a total amount of 80 mol % or more and a trivalent or higher polycarboxylic acid (x2); the component (y) comprises a polyester resin (P) which is constituted by a polyester resin (A) comprising 80 mol % or more of an aliphatic diol (y1) having 2 to 10 carbon atoms optionally together with a linear polyester resin (B); and the storage modulus at 150&#xb0; C. [G'150] of resin (A) is 20000 dyn/cmor more and the ratio of [G&#x2032;150] to the storage modulus as 180&#xb0; C. [G&#x2032;180] thereof, i.e., [G&#x2032;150]/[G&#x2032;180], is 15 of less.

Growing community of inventors

Kyoto, Japan

Yuya Iwagoe