Abstract: Modified nigrosine which has satisfactory dispersibility in resin and which reduces the residual aniline amount is offered, and its production method is also offered. Moreover, toner for developing electrostatic charge images is offered, which uses modified nigrosine colorant that resolves the aforementioned problems, which has excellent charge-imparting properties, which exhibits no fogging, which experiences no scattering of toner inside the developing apparatus, and which has little fluctuation of image density. Modified nigrosine, which is nigrosine (b) that has been modified by rosin-modified resin (a) with an acid value of 110 or less.

Abstract: Modified nigrosine which has satisfactory dispersibility in resin and which reduces the residual aniline amount is offered, and its production method is also offered. Moreover, toner for developing electrostatic charge images is offered, which uses modified nigrosine colorant that resolves the aforementioned problems, which has excellent charge-imparting properties, which exhibits no fogging, which experiences no scattering of toner inside the developing apparatus, and which has little fluctuation of image density. Modified nigrosine, which is nigrosine (b) that has been modified by rosin-modified resin (a) with an acid value of 110 or less.

Abstract: The present invention provides a carrier for electrophotography, which is capable of charging the toner in the developer very rapidly to a target electrostatic charge and at the same time, is capable of maintaining the target electrostatic charge during printing, so that the chemical fogging related to the slow charging rate can be eliminated and the image density related to the maintenance of the electrostatic charge can be preserved during printing. The charging rate and the charge maintenance of the electrophotographic carrier can be preserved if the carrier composed of magnetic core particles and the resin coat satisfies the following equation (B)>[(−19.4)×(A)+31], wherein (A) represents a carbon content (weight %) of the carrier and (B) represents a ratio of the square root of the number of emitted photoelectrons ((CPS)½) and the photon energy (eV).

Abstract: An object of the present invention is to provide a developer for electrostatic image development, which exhibits stable charge behavior during printing even when using a polyester resin and does not cause contamination of the inside of the apparatus because of less scattering of the toner, and also facilitates easy maintenance. The developer for electrostatic image development of the present invention comprises colored resin particles comprising at least a binder resin and a colorant, and a magnetic carrier, wherein a proportion of said colored resin particles having a particle diameter in a range of from 12 &mgr;m to 16 &mgr;m, inclusive, in said developer and a specific charge amount of said colored resin particles meet the following expression (1): 5.18+0.

Abstract: The present invention relates to a developer for electrostatic image development comprising: a toner for electrostatic image development which comprises a resin and a colorant; and a carrier formed by a carrier core material and a resin layer including a resistance control agent which is formed on the surface of the carrier core material, wherein the resin layer of the carrier has a concentration gradient of the resistance control agent toward the thickness direction of the resin layer, a concentration of the resistance control agent is the highest in the vicinity of the carrier core material, and is gradually lowered toward the surface of the resin layer, and the resistance control agent is present on the surface of the resin layer, as well as relates to an image forming method, wherein it comprises a step of developing an electrostatic image at a developing speed of 20 m/min or higher, by means of employing the developer for electrostatic image development.

Abstract: The present invention provides a carrier for electrophotography, which is capable of charging the toner in the developer very rapidly to a target electrostatic charge and at the same time, is capable of maintaining the target electrostatic charge during printing, so that the chemical fogging related to the slow charging rate can be eliminated and the image density related to the maintenance of the electrostatic charge can be preserved during printing. The charging rate and the charge maintenance of the electrophotographic carrier can be preserved if the carrier composed of magnetic core particles and the resin coat satisfies the following equation (B)>[(−19.4)×(A)+31], wherein (A) represents a carbon content (weight %) of the carrier and (B) represents a ratio of the square root of the number of emitted photoelectrons ((CPS)½) and the photon energy (eV).

Abstract: The present invention relates to a developer for electrostatic image development comprising: a toner for electrostatic image development which comprises a resin and a colorant; and a carrier formed by a carrier core material and a resin layer including a resistance control agent which is formed on the surface of the carrier core material, wherein the resin layer of the carrier has a concentration gradient of the resistance control agent toward the thickness direction of the resin layer, a concentration of the resistance control agent is the highest in the vicinity of the carrier core material, and is gradually lowered toward the surface of the resin layer, and the resistance control agent is present on the surface of the resin layer, as well as relates to an image forming method, wherein it comprises a step of developing an electrostatic image at a developing speed of 20 m/min or higher, by means of employing the developer for electrostatic image development.

Abstract: The present invention provides a toner for electrostatic image development which reconciles anti-offset properties and fixation properties and is superior in resistance to abrasion and peel of the fixed image in uses where the development and fixation are conducted at a wide range of a fixing speed, particularly high speed which exceeds 20 or 30 m/min. The toner comprises a polyester resin, a colorant, and a releasing agent, wherein the flow beginning temperature Tfb of the toner as measured by a constant load extrusion type capillary rheometer is within a range of 70-105° C. and the flow ending temperature Tend is within a range of 120-144° C.

Abstract: An object of the present invention is to provide a developer for electrostatic image development, which exhibits stable charge behavior during printing even when using a polyester resin and does not cause contamination of the inside of the apparatus because of less scattering of the toner, and also facilitates easy maintenance.

Abstract: 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%.

Abstract: An electrostatic image developer is provided which has superior fixation properties and anti-offset properties, exhibits stable charge behavior even during continuous printing, and has superior durability and permits a high-quality image to be obtained.

Abstract: A color toner composition for an electrostatic developer is disclosed, comprising a cyan pigment, a magenta pigment or a yellow pigment, a binder resin and a negative charging-controlling agent, wherein the binder resin is a vinyl-modified polyester resin as obtained by graft polymerizing.(b) a vinyl monomer component containing an aromatic vinyl monomer and an amino group-containing vinyl monomer to(a) an unsaturated polyester component containing at least aliphatic unsaturated dibasic acid and polyhydric alcohol, said component (a) constituting at least 50% by weight of the vinyl-modified polyester resin and said amino group-containing vinyl monomer constitutes 0.1 to 2% by weight of the vinyl-modified polyester resin.

Abstract: A color toner composition for developing electrostatic images comprises a coloring agent and a binder resin, wherein the binder resin is a vinyl-modified polyester resin obtained by graft polymerizing(a) a vinyl monomer containing an aromatic vinyl monomer and an amino group-containing vinyl monomer to(b) an unsaturated polyester comprising at least aliphatic unsaturated dibasic acid and polyhydric alcohol having a weight average molecular weight of about 5,000 to 15,000, and the component (b) constitutes at least 50% by weight of the vinyl-modified polyester resin and the amino group-containing vinyl monomer constitutes 2 to 20% by weight of the vinyl-modified polyester resin.