JP2008309984A - Two component developer, and developer for replenishment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two component developer capable of achieving: the improvement of dot reproducibility in an electrostatic latent image; the prevention of image density lowering at the tail end of a solid image section; the prevention of the sticking of a carrier to a photoreceptor drum; and the prevention of image density lowering when being left alone under high temperature-high humidity. <P>SOLUTION: Disclosed is a two component developer comprising: magnetic carriers; and toner, and each magnetic carrier comprises resin-containing magnetic particles in which the vacancy of each porous magnetic core particle includes a resin component. The two component developer is used for an image forming apparatus using a photoreceptor provided with: a conductive substrate; a photoconductive layer at least including amorphous silicon on the conductive substrate; and a surface protective layer. Regarding each porous magnetic core particle, provided that compaction apparent density is defined as ρ1 (g/cm<SP>3</SP>) and true density is defined as ρ2 (g/cm<SP>3</SP>), ρ1 is 0.80 to 2.40 and ρ1/ρ2 is 0.20 to 0.42, the specific resistance (Ω cm) of each porous magnetic core particle satisfies 1.0×10<SP>3</SP>to 5.0×10<SP>7</SP>, and the specific resistance (Ω cm) of each magnetic carrier satisfies 1.0×10<SP>10</SP>to 1.0×10<SP>17</SP>. The toner comprises toner particles at least comprising a binder resin and a release agent, and has one or more heat absorption peaks in the temperature range of 30 to 200°C in a heat absorption curve measured with a differential scanning calorimeter, and the peak temperature of the maximum heat absorption peak in the one or more heat absorption peaks is 55 to 140°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a two-component developer and a replenishment developer used in an electrophotographic system, an electrostatic recording system, and an electrostatic printing system.

Development methods such as electrophotography include a one-component development method that uses only toner and a two-component development method that uses a mixture of carrier and toner.
Since the two-component development method uses a carrier, the triboelectric charging area of the carrier with respect to the toner is wide, so the charging characteristics are more stable than the one-component development method, and it is advantageous for maintaining high image quality over a long period of time. It is. In addition, since the toner supply amount capability of the carrier to the development area is high, it is often used particularly for a high-speed machine.
In recent years, electrophotographic systems have been used not only for printing documents, but also for printing that requires high image quality such as photographs and printing that requires high speed and high durability such as POD.

As the carrier, for example, a magnetic carrier in which a polymer is contained in a porous magnetic carrier core (see Patent Document 1) or a first coating layer and a first coating layer contained in the porous magnetic carrier core are further coated. A magnetic carrier (see Patent Document 2) provided with a second coating layer has been proposed.
The magnetic carrier has achieved triboelectric charging and charging stability, but when used for a long period of time, the reproducibility of the dots of the electrostatic latent image is reduced, the surface of the photosensitive drum is scratched, and the image quality is low. There was a problem of lowering.
Also proposed is a resin-coated magnetic carrier in which a porous magnetic material is used as the magnetic carrier core material and a resin is contained in the porous magnetic material, and the resistance LogR when 500 volts is applied is 10.0 Ωcm or more (see Patent Document 3). Has been.
By using the above-mentioned resin-coated magnetic carrier, it is possible to prevent white spots on the photosensitive drum due to carrier adhesion to the image and breakdown of the magnetic carrier, but there is a problem that density reduction occurs at the rear end of the solid image portion. was there.

On the other hand, in the recent OA market, the diversification and sophistication of information has led to the colorization of images output in offices, and further, there has been a demand for speeding up and stabilization of the system. Accordingly, the development of mounting an amorphous silicon photosensitive body, which is extremely excellent in stability, wear resistance, and the like and most suitable for an ultra-high speed heavy duty machine, to a full-color electrophotographic apparatus is in progress. Considering the development status of color developers, a combination of an amorphous silicon photoreceptor and development with a non-magnetic toner is considered necessary.
When the resin-coated magnetic carrier of Patent Document 3 is used in an image forming apparatus equipped with an amorphous silicon photoconductor, filming on the photoconductor is likely to occur.
Further, when titanium oxide having a volume resistivity of 1 × 10 ⁵ to 1 × 10 ⁹ Ω · cm is externally added and the electric field strength is 6 × 10 ⁴ V / m, the electric resistance is 1 × 10 ⁷ to 1 ×. Although an example of a two-component developer using a magnetic powder of 10 ¹¹ Ω (see Patent Document 4) has been described, cleaning of the photoreceptor was insufficient.
As described above, various proposals have been made. However, there is a demand for an optimum developer for an image forming apparatus equipped with an amorphous silicon photoreceptor.
JP-A-11-295933 JP 2003-131436 A JP2004-0775568 JP 2004-325681 A

The object of the present invention is to improve dot reproducibility of an electrostatic latent image, to prevent a decrease in image density at the rear end of a solid image portion, to prevent carrier adhesion to a photosensitive drum, and to reduce image density when left at high temperature and high humidity. The present invention provides a two-component developer and a replenishment developer capable of achieving prevention.
Furthermore, an object of the present invention is to provide a two-component developer and a replenishment developer that can achieve improved cleaning properties and prevention of filming on the photoreceptor, particularly in an image forming apparatus equipped with an amorphous silicon photoreceptor. .

The present invention is as follows.
(1) A two-component developer containing a magnetic carrier and a toner, wherein the magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles, The two-component developer includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. The porous magnetic core particles are used in an image forming apparatus using a photoconductor provided with a surface protective layer containing at least one selected, and the porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 ( in case of a g / cm ^3), ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 or more, 0.42 or less There, the specific resistance of the porous magnetic core particles, 1.0 × 10 ³ Ω · cm or more, or less 5.0 × 10 ⁷ Ω · cm, the specific resistance of the magnetic carrier, 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less, and the toner contains toner particles containing at least a binder resin and a release agent, and is measured by a differential scanning calorimeter (DSC). The endothermic curve has one or more endothermic peaks in the temperature range of 30 ° C. or higher and 200 ° C. or lower, and the peak temperature of the maximum endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower. A two-component developer characterized by
(2) The toner contains fine particles having a number average particle diameter of 60 nm or more and 300 nm or less, and the content of the fine particles is 0.5 parts by mass or more and 4.0 parts by mass with respect to 100 parts by mass of the toner particles. The two-component developer according to (1), wherein the two-component developer is at most parts.
(3) The two-component developer according to (1) or (2), wherein the resin component contains at least a silicone resin and a coupling agent.
(4) The toner comprises at least a copolymer polymerized using one or more (meth) acrylic acid monomers selected from styrene monomers and (meth) acrylic acid monomers, and polyolefin. The two-component developer according to any one of (1) to (3), wherein the two-component developer contains a release agent dispersant.
(5) Replenishment development used in a two-component development method in which a replenishment developer containing at least toner and a magnetic carrier is replenished to the developing unit, and at least the excess magnetic carrier in the developing unit is discharged from the development unit. The replenishment developer contains the toner in a blending ratio of 2 parts by mass or more and 50 parts by mass or less with respect to 1 part by mass of the magnetic carrier. A carrier containing resin-containing magnetic particles containing a resin component in the pores of the core particles, the two-component developer comprising: a conductive substrate; and a photoconductive layer containing at least amorphous silicon on the conductive substrate; A surface protective layer comprising at least one selected from the group consisting of amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer; In the image forming apparatus using the photoconductor provided with the above, the porous magnetic core particle has a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 (g / cm ³ ). There 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 or more and 0.42 or less, the specific resistance of the porous magnetic core particles, 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less, and the specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less. The toner contains toner particles containing at least a binder resin and a release agent, and has an endothermic curve measured by a differential scanning calorimeter (DSC) of 1 in a temperature range of 30 ° C. or higher and 200 ° C. or lower. Having one or more endothermic peaks, A developer for replenishment having a peak temperature of a large endothermic peak of 55 ° C. or more and 140 ° C. or less.
(6) The toner contains fine particles having a number average particle diameter of 60 nm or more and 300 nm or less, and the content of the fine particles is 0.5 parts by mass or more and 4.0 parts by mass with respect to 100 parts by mass of the toner particles. (5) The developer for replenishment according to (5).
(7) The replenishment developer according to (5) or (6), wherein the resin component contains at least a silicone resin and a coupling agent.
(8) The toner comprises at least a copolymer polymerized using one or more (meth) acrylic acid monomers selected from styrene monomers and (meth) acrylic acid monomers, and polyolefin. The replenishment developer according to any one of (5) to (7), which contains a release agent dispersant.
(9) A conductive substrate, a photoreceptor having at least a photoconductive layer on the conductive substrate, and a developer carrier that carries a two-component developer containing a magnetic carrier and a toner are arranged to face each other. In the image forming method to be provided and developed, the photoconductor further includes a surface protective layer including at least one selected from the group consisting of amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer, The magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles, and the porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ), The true density is ρ2 (g / cm
In case of a ^3), .rho.1 is 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 to 0.42, the specific resistance of the porous magnetic core particles Is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less, and the specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more, 1.0 × 10 ¹⁷ Ω · cm or less, and the toner contains at least a binder resin and a release agent, and has an endothermic curve measured by a differential scanning calorimeter (DSC) in a temperature range of 30 ° C. or more and 200 ° C. or less. An image forming method comprising one or a plurality of endothermic peaks, wherein a peak temperature of a maximum endothermic peak among the endothermic peaks is 55 ° C or higher and 140 ° C or lower.

The two-component developer and the replenishment developer according to the present invention improve the dot reproducibility of the electrostatic latent image, prevent the image density from decreasing at the rear end of the solid image portion, prevent the carrier from adhering to the photosensitive drum, and high temperature and high humidity. It is possible to prevent the image density from being lowered when left under.
Further, the two-component developer and the replenishment developer of the present invention can improve the cleaning property and prevent filming on the photoreceptor, particularly in an image forming apparatus equipped with an amorphous silicon photoreceptor.

The two-component developer of the present invention is a two-component developer containing a magnetic carrier and a toner, and the magnetic carrier comprises resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles. The two-component developer is a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. The porous magnetic core particles are used in an image forming apparatus using a photoreceptor provided with a surface protective layer containing at least one selected from the group consisting of rides. The porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ), true when the density ^{ρ2 (g / cm 3),} ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 or more, 0.4 2 or less, the specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less, and the specific resistance of the magnetic carrier is 1.0 × 10 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less, and the toner contains toner particles containing at least a binder resin and a release agent, and is measured by a differential scanning calorimeter (DSC). Endothermic curve having one or more endothermic peaks in the temperature range of 30 ° C. or higher and 200 ° C. or lower, and the peak temperature of the maximum endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower. Features.
On the other hand, the replenishment developer of the present invention is a two-component that replenishes the developer with a replenishment developer containing at least toner and a magnetic carrier, and discharges at least the excess magnetic carrier inside the developer from the developer. A replenishment developer used in the development method, wherein the replenishment developer contains toner in a blending ratio of 2 parts by mass or more and 50 parts by mass or less with respect to 1 part by mass of the magnetic carrier. , A carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles, and the two-component developer includes a conductive substrate and light containing at least amorphous silicon on the conductive substrate. Surface protection comprising a conductive layer and at least one selected from the group consisting of amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer Used in an image forming apparatus using a photosensitive member comprising bets, porous magnetic core particles, .rho.1 the packed bulk density (g / cm ^3), when the true density was [rho] 2 (g / cm ^3), .rho.1 There 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 or more and 0.42 or less, the specific resistance of the porous magnetic core particles, 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less, and the specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less, The toner contains toner particles containing at least a binder resin and a release agent, and one or more in a temperature range of 30 ° C. or higher and 200 ° C. or lower in an endothermic curve measured by a differential scanning calorimeter (DSC). Endothermic peak, and the peak of the endothermic peak in the endothermic peak Peak temperature, characterized in that temperatures above 55 ℃ is 140 ° C. or less.

  The magnetic carrier used in the two-component developer and the replenishment developer of the present invention (hereinafter also referred to as the developer of the present invention) is a resin-containing magnetic particle containing a resin component in the pores of the porous magnetic core particle. Is a carrier containing The resin-containing magnetic particles can be used as they are as a magnetic carrier. Further, the resin-containing magnetic particles are particles that serve as a carrier core when a coating layer is provided on the surface of the carrier core for the purpose of contamination resistance, charge amount adjustment, and the like.

The porous magnetic core particle has a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 (g / cm ³ ), and ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm. ³ or less and (preferably 0.90 g / cm ³ or more, 2.30 g / cm ³ or less), ρ1 / ρ2 is 0.20 or more 0.42 or less (preferably .rho.1 / [rho] 2 is 0.21 or more 0 .40 or less). The specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less.
When a packed bulk density of the porous magnetic core particles of the magnetic carrier and ^{ρ1 (g / cm 3),} ρ1 is 0.80 g / cm ³ or more, the electrostatic latent by a 2.40 g / cm ³ or less An improvement in the dot reproducibility of the image can be achieved.
To improve dot reproducibility, use porous magnetic core particles with pores inside and adjust the ratio of the pores to the porous magnetic core particles so that ρ1 is 2.40 g / cm ³ or less. is required. As a result, the amount of magnetization of the magnetic carrier is reduced, the ears of the magnetic brush on the developing sleeve are dense, and dot reproducibility can be improved. However, if ρ1 is made smaller than 0.80 g / cm ^{3, the} amount of magnetization of the magnetic carrier becomes too low, and the magnetic carrier is not held on the developing sleeve at the time of development but is developed on the photosensitive drum. Carrier adheres. As a result, black spots of magnetic carriers appear on the image.
Therefore, when the packed bulk density of the porous magnetic core particles and ^{ρ1 (g / cm 3),} ρ1 is 0.80 g / cm ³ or more, it is necessary to 2.40 g / cm ³ or less .
At the same time, when the apparent apparent density of the porous magnetic core particles is ρ1 (g / cm ³ ) and the true density is ρ2 (g / cm ³ ), ρ1 / ρ2 is 0.20 or more and 0.42 or less. Thus, an image having a large image area (for example, an image area of 50%) is converted into a room temperature and low humidity (for example, 23 ° C.).
/ 5RH%) Even when 100,000 sheets are printed in an environment, a decrease in image density can be prevented.
In order to prevent a decrease in image density when an image having a large image area is used at room temperature and low humidity for a long period of time, porous magnetic core particles having pores are used, and voids inside the porous magnetic core particles are used. It is necessary to make the pores contain a resin component and make ρ1 / ρ2 be 0.42 or less. However, if ρ1 / ρ2 is less than 0.20, the amount of magnetic components present in the magnetic carrier becomes too small, and the magnetic carrier is not held on the developing sleeve during development but is developed on the photosensitive drum, and the magnetic drum is magnetically Carrier will adhere. As a result, black spots of carriers are generated on the image.
Therefore, when the apparent apparent density of the porous magnetic core particles is ρ1 (g / cm ³ ) and the true density is ρ2 (g / cm ³ ), ρ1 / ρ2 is 0.20 or more and 0.42 or less. Is necessary.

Furthermore, the specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less (preferably 1.0 × 10 ⁴ Ω · cm or more, 1. 0 × 10 ⁷ Ω · cm or less) can prevent a decrease in image density at the rear end of the solid image portion.
The inventors presume this reason as follows.
When the toner is developed, a counter charge having a polarity opposite to that of the toner remains on the magnetic carrier. Since this charge pulls back the toner developed on the photosensitive drum, the density of the portion is lowered. However, by setting the specific resistance of the porous magnetic core particles to 5.0 × 10 ⁷ (Ω · cm) or less, the charge having the opposite polarity to the toner remaining on the magnetic carrier is developed through the porous magnetic core particles. Can escape to the sleeve. For this reason, there is no force to pull back the toner, and a decrease in image density is suppressed even at the rear end of the solid image portion.
However, if the specific resistance of the porous magnetic core particles is smaller than 1.0 × 10 ³ (Ω · cm), the magnetic carrier formed on the developing sleeve when an electric field is applied between the developing sleeve and the photosensitive drum during development. In some cases, the electric charge flows through the photosensitive drum and the electrostatic latent image on the photosensitive drum is erased. For this reason, the specific resistance of the porous magnetic core particles needs to be 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less.

Next, a specific method for adjusting the apparent apparent density, true density, and specific resistance of the porous magnetic core particles to the above ranges will be described. As a method for adjusting these physical properties, an appropriate element type used for the porous magnetic core particle is selected, and the crystal diameter, pore diameter, pore diameter distribution, pore ratio, etc. of the porous magnetic core particle are determined. Examples of the control method include the following methods.
i) The crystal growth degree and growth rate are controlled by adjusting the temperature and time during firing of the porous magnetic core particles, and the size and distribution of the pores are adjusted.
ii) When forming the porous magnetic core particles, a pore forming agent such as a foaming agent or organic fine particles is added to generate pores inside the core particles. At that time, the hole diameter, hole diameter distribution, and hole ratio are adjusted by controlling the type (composition, diameter, diameter distribution, etc.), amount, and firing time of the hole forming agent.
The foaming agent described above is not particularly limited as long as it is a substance that vaporizes or decomposes at 60 to 180 ° C. and generates gas at that time. For example, the following are mentioned. Foamable azo polymerization initiators such as azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanecarbonitrile; metal hydrogen carbonates such as sodium, potassium, calcium; ammonium hydrogen carbonate, ammonium carbonate, carbonic acid Calcium, ammonium nitrate, azide compound, 4,4'-oxybis (benzenesulfohydrazide), allylbis (sulfohydrazide), diaminobenzene.
Examples of the organic fine particles include resins used as waxes; thermoplastic resins such as polystyrene, acrylic resins, and polyester resins; thermosetting resins such as phenol resins, polyesters, urea resins, melamine resins, and silicone resins. These are used in the form of fine particles.
A known method can be used as the method for forming the fine particles. For example, the particles are pulverized to a desired particle size in the pulverization step. In the pulverization process, coarse pulverization is performed with a pulverizer such as a crusher, a hammer mill, or a feather mill. / SNNB liner), and finely pulverized by an air jet fine pulverizer.
Further, classification may be performed after pulverization to adjust the particle size distribution of the fine particles. Examples of the classifier include a classifier and a sieving machine such as an inertia class elbow jet (manufactured by Nippon Steel Mining Co., Ltd.) and a centrifugal class turbocharger (manufactured by Hosokawa Micron Co., Ltd.). The pore diameter, diameter distribution, and porosity of the porous magnetic core particles can be adjusted by the diameter, diameter distribution, and amount of the fine particles used.

  Moreover, the following are mentioned as a material of the said porous magnetic core particle. 1) Iron powder with oxidized surface 2) Unoxidized iron powder 3) Metal particles such as lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium and rare earth elements 4) Iron, lithium Alloy particles of metals such as calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium and rare earth elements, or oxide particles containing these elements, 5) magnetite particles or ferrite particles.

The ferrite particles are a sintered body represented by the following formula.
(M1 ₂ O) _w (M2O) _x (M3 ₂ O ₃ ) _y (Fe ₂ O ₃ ) _z
(In the formula, M1 is a monovalent metal atom, M2 is a divalent metal atom, M3 is a trivalent metal, w + x + y + z = 1.0, and w, x, and y are each 0. ≦ (w, x, y) ≦ 1.0, and z is 0.2 <z <1.0.)
In the above formula, as M1 to M3, a metal atom selected from the group consisting of Ni, Cu, Zn, Li, Mg, Mn, Sr, Ca, and Ba can be used.
For example, there are magnetic Li-based ferrite, Mn-Zn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, Cu-Zn-based ferrite, Ni-Zn-based ferrite, Ba-based ferrite, and Mn-based ferrite.
From the viewpoint of easy control of the crystal growth rate, Mn-based ferrite or Mn-Mg-based ferrite containing Mn element is preferable.
In addition to selecting the type of magnetic material, the specific resistance of the porous magnetic core particle can be adjusted by heat-treating the porous magnetic core particle in an inert gas and reducing the surface of the porous magnetic core particle. Can do. For example, heat treatment is performed at 600 ° C. or higher and 1000 ° C. or lower in an inert gas (eg, nitrogen) atmosphere.

Next, the magnetic carrier will be described.
In order to achieve both high image quality and high durability, it is necessary to have a high resistance as a developer when using a photoreceptor having a relatively low resistance, such as a photoreceptor containing amorphous silicon, as an electrostatic latent image carrier. It is known that The specific resistance of the magnetic carrier used in the present invention is 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less, preferably 1.0 × 10 ¹³ Ω · cm or more, 1 0.0 × 10 ¹⁶ Ω · cm or less. If the specific resistance of the magnetic carrier is less than 1.0 × 10 ¹⁰ Ω · cm, when using a photoconductor containing amorphous silicon, electrostatic latent is caused by carrier adhesion or charge injection by the magnetic brush of the magnetic carrier. May disturb the image. On the other hand, if the specific resistance of the magnetic carrier exceeds 1.0 × 10 ¹⁷ Ω · cm, carrier adhesion may occur instead due to the generation of residual charges. In addition, a decrease in image density may occur.
In addition, when a high-hardness photoconductor such as a photoconductor containing amorphous silicon is used, it has been very difficult to satisfy the cleaning performance of the photoconductor. However, the magnetic carrier has a high resistance as in the present invention, and the ratio ρ1 / ρ2 between the apparent apparent density ρ1 (g / cm ³ ) and the true density ρ2 (g / cm ³ ) of the porous magnetic core particles is 0. .20 or more, 0
. It has been found that the cleaning performance of the photoreceptor is remarkably improved when it satisfies 42 or less.
The inventors presume this reason as follows.
The magnetic carrier used in the present invention is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles, and the proportion of the resin component in the magnetic carrier is a conventional ferrite carrier It is higher than Further, the coating resin is thickly coated to increase the resistance of the magnetic carrier. For this reason, the elasticity of the magnetic carrier is increased, and the load of the magnetic carrier on the developing sleeve and the contact of the photosensitive member during development can be reduced. This is presumed that the adhesion force other than the electrostatic force to the photosensitive member is reduced and the toner is easily cleaned.

  As the resin component contained in the porous magnetic core particle, either a thermoplastic resin or a thermosetting resin may be used, but the wettability of the porous magnetic core particle to the magnetic component is high. Is preferred. When a resin component having high wettability is used, the surface of the porous magnetic core particle can be easily covered with the resin at the same time when the resin component is contained in the pores of the porous magnetic core particle.

The following are mentioned as said thermoplastic resin. Polystyrene; Acrylic resin such as polymethyl methacrylate and styrene-acrylic acid copolymer; Styrene-butadiene copolymer; Ethylene-vinyl acetate copolymer; Polyvinyl chloride; Polyvinyl acetate; Polyvinylidene fluoride resin; Fluorocarbon resin; Fluorocarbon resin; Solvent-soluble perfluorocarbon resin; Polyvinyl pyrrolidone; Petroleum resin; Novolak resin; Saturated alkyl polyester resin; Aromatic polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyarylate; Polyamide resin; Polyacetal resin; Polycarbonate resin; Sulfone resin; polysulfone resin; polyphenylene sulfide resin; polyether ketone resin.
The following are mentioned as said thermosetting resin. Phenolic resin, modified phenolic resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, unsaturated polyester obtained by polycondensation of maleic anhydride, terephthalic acid and polyhydric alcohol, urea resin, melamine resin, urea-melamine resin , Xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin, furan resin, silicone resin, polyimide, polyamideimide resin, polyetherimide resin, polyurethane resin.
Further, a resin obtained by modifying these resins may be used. Among these, fluorine-containing resins such as polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin or solvent-soluble perfluorocarbon resin, acrylic-modified silicone resin or silicone resin are preferable because of high wettability with respect to the magnetic component of the porous magnetic core particles.
Of the above resins, silicone resins are particularly preferred. As the silicone resin, conventionally known silicone resins can be used. Specifically, a straight silicone resin composed only of an organosiloxane bond and a silicone resin obtained by modifying the straight silicone resin with alkyd, polyester, epoxy, urethane, or the like can be given. Moreover, the following are mentioned as a commercially available silicone resin. Examples of the straight silicone resin include KR271, KR255, and KR152 manufactured by Shin-Etsu Chemical Co., Ltd., and SR2400 and SR2405 manufactured by Toray Dow Corning. Examples of the modified silicone resin include KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical, SR2115 (epoxy modified), SR2110 (alkyd) manufactured by Toray Dow Corning. Modification) and the like.

Further, the resin component particularly preferably contains at least a silicone resin and a coupling agent.
For example, as a silane coupling agent, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane , N-propyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane and vinyltris (β-methoxy) silane.
In addition, as a silane coupling agent having a hydrophobic group, vinyltrichlorosilane, hexamethyldisilazane, trimethylsilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane A compound selected from the group consisting of prommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, and chloromethyldimethylchlorosilane may be used. Examples of the silane coupling agent having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxydiethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxy. Examples include silane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane. Examples of the silane coupling agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, and β- (3,4-epoxycyclohexyl) trimethoxysilane.
The addition amount is preferably treated with 0.1 to 10 parts by weight (more preferably 0.2 to 6 parts by weight) of a coupling agent with respect to 100 parts by weight of the porous magnetic core particles.

As a method for incorporating a resin component inside the porous magnetic core particle, it is common to dilute the resin component in a solvent and add it to the porous magnetic core particle. The solvent used here should just be what can melt | dissolve each resin component. When the resin is soluble in an organic solvent, examples of the organic solvent include toluene, xylene, cellosolve butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol. In the case of a water-soluble resin component or an emulsion type resin component, water may be used as a solvent. As a method for adding a resin component diluted with a solvent to the inside of the porous magnetic core particles, the resin component is impregnated by a coating method such as a dipping method, a spray method, a brush coating method, and a fluidized bed, The method of volatilizing a solvent is mentioned.

In order to uniformly contain the resin component inside the porous magnetic core particles, the viscosity (25 ° C.) of the resin component solution to be contained is more preferably 0.6 to 100 (Pa · s). . When a resin component solution having a viscosity higher than 100 (Pa · s) is used, the resin component solution is difficult to uniformly penetrate into the inside (holes) of the porous magnetic core particles because the viscosity is high. If it is less than 0.6 (Pa · s), the amount of the resin component is small, and the adhesive force of the resin component to the porous magnetic core particles may be reduced when the solvent is volatilized.
The magnetic carrier may further include a resin component that covers the surface of the porous magnetic core particle, in addition to the resin component contained in the porous magnetic core particle. In that case, the resin component contained inside the porous magnetic core particle and the resin component covering the surface of the porous magnetic core particle may be the same or different.

Next, a specific method for adjusting the magnetic carrier to a high resistance will be described.
The resistance of the magnetic carrier can be increased by increasing the amount of resin to be coated (coated) and not exposing the porous magnetic core particles to the surface, but in order to make the thickness of the coated resin uniform. In addition, it is preferable to coat the resin component in two or more layers.
Further, as in the present invention, in the porous magnetic core particles having pores therein, it is more preferable that the resin is sufficiently contained in the pores. In such a case, for example, the viscosity of the resin component solution used in the coating of the first layer is slightly lowered so that the resin component solution can sufficiently penetrate into the pores. The second and subsequent layers are coated with a slightly higher viscosity than the resin component solution used in the first layer, whereby a magnetic carrier having a uniform coating thickness and a high resistance can be prepared.

  The volume distribution standard 50% particle diameter (D50) of the magnetic carrier is 20 μm or more and 70 μm or less (more preferably 25 μm or more and 60 μm or less). It is preferable from the viewpoint of carrier adhesion prevention and fog prevention.

The toner used in the present invention contains toner particles containing at least a binder resin and a release agent, and has a temperature range of 30 ° C. or higher and 200 ° C. or lower in an endothermic curve measured by a differential scanning calorimeter (DSC). The peak temperature of the maximum endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower, more preferably 60 ° C. or higher and 110 ° C. or lower. The peak temperature of the maximum endothermic peak in the above endothermic peak is selected so that the peak temperature of the maximum endothermic peak is 55 ° C. or higher and 140 ° C. or lower when the release agent contained in the present invention is measured by DSC. Therefore, it is possible to adjust to the above range.
The developer using the toner and the magnetic carrier can effectively prevent a decrease in image density during initial and long-term durability.
Further, since the toner contains a release agent, the toner can be fixed without applying oil to the fixing device, and the gloss of the fixed image can be controlled.
When the peak temperature of the maximum endothermic peak of the toner is less than 55 ° C., when the developer is used for a long time, the release agent in the toner tends to adhere to the magnetic carrier, and the charging performance of the magnetic carrier tends to decrease. As a result, even when the magnetic carrier is used, the image density is likely to be lowered during long-term use.
Further, when the peak temperature of the maximum endothermic peak of the toner is higher than 140 ° C., the dispersibility of the release agent in the toner is poor due to poor mixing of the toner binder resin and the release agent. Tend to decrease, and fog is likely to occur.
From this, the endothermic curve measured by a differential scanning calorimeter (DSC) has one or more endothermic peaks in the temperature range of 30 to 200 ° C., and the peak temperature of the maximum endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower, more preferably 60 ° C. or higher and 110 ° C. or lower, and a developer using the above magnetic carrier, which effectively prevents a decrease in image density during initial and long-term durability. can do.

Further, when a photoconductor containing amorphous silicon is used as in the present invention, the toner resistance can be increased by adding a release agent, so that the latent image is hardly disturbed.
The release agent is preferably used in an amount of 0.5 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the binder resin.
Examples of the release agent include the following. Low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymer, hydrocarbon wax such as microcrystalline wax, paraffin wax, Fischer-Tropsch wax; oxide of hydrocarbon wax such as oxidized polyethylene wax or block copolymer thereof; Waxes mainly composed of fatty acid esters such as carnauba wax, behenic acid behenate wax, and montanic acid ester wax; fatty acid esters such as deoxidized carnauba wax that have been partially or fully deoxidized.
Furthermore, the following are mentioned. Saturated linear fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brandic acid, eleostearic acid and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, Saturated alcohols such as sil alcohols; polyhydric alcohols such as sorbitol; fatty acids such as palmitic acid, stearic acid, behenic acid, montanic acid, and stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, Esters with alcohols such as sil alcohols; Fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; Methylene bis stearic acid amide, ethylene biscapric acid Saturated fatty acid bisamides such as amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N 'dioleyl adipic acid amide, N, N' dioleyl Unsaturated fatty acid amides such as sebacic acid amides; aromatic bisamides such as m-xylene bis-stearic acid amide, N, N ′ distearyl isophthalic acid amide; calcium stearate, calcium laurate, zinc stearate, magnesium stearate Aliphatic metal salts such as those commonly referred to as metal soaps; waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; fatty acids such as behenic acid monoglycerides Alcohol Partial ester; methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable fats and oils.

The toner used in the present invention comprises a copolymer obtained by polymerizing one or more (meth) acrylic acid monomers selected from styrene monomers and (meth) acrylic acid monomers, and a polyolefin. It is preferable to further contain at least a release agent dispersant. The release agent dispersant is preferably used in an amount of 0.5 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the binder resin.

In the present invention, the addition of the release agent dispersant has the effect of making the resistance of the toner uniform and making it difficult to disturb the latent image. Further, the cleaning property can be improved.

Examples of the styrene monomer and (meth) acrylic acid monomer used to obtain the copolymer include the following.
For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4 -Dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn- Styrene such as dodecylstyrene and derivatives thereof; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , Phenyl methacrylate, methacrylate Α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl acid, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, Acrylic acid esters such as dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide.
Also, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride Unsaturated dibasic acid anhydride; maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Unsaturated dibasic acid half esters such as alkenyl succinic acid methyl half ester, fumaric acid methyl half ester, mesaconic acid methyl half ester; dimethyl maleic acid, unsaturated dibasic acid ester such as dimethyl fumaric acid; acrylic acid, Le acid, crotonic acid, such as cinnamic acid alpha, beta-unsaturated acids;
Α, β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, anhydrides of the α, β-unsaturated acid and lower fatty acids; alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, these Monomers having a carboxyl group, such as acid anhydrides and monoesters thereof.
Furthermore, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) -Methylhexyl) A monomer having a hydroxyl group such as styrene.
Among them, a styrene-acrylonitrile-butyl acrylate terpolymer is particularly preferable.
On the other hand, polyolefins are homopolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, copolymers of two or more α-olefins or oxides of polyolefins. Furthermore, these polyolefins may be vinyl-based graft-modified polyolefins.
The physical properties are, for example, those having a low molecular weight of preferably 2000 to 30000 in weight average molecular weight (Mw) in GPC measurement.

  As a method of adding the release agent and the release agent dispersant, the release agent and the release agent dispersant are dispersed in the binder resin in advance, not simultaneously with the binder resin and other materials at the time of toner production. It is preferable to add in a fresh state.

The toner contains fine particles having a number average particle diameter of 60 nm or more and 300 nm or less, and the addition amount of the fine particles is 0.5 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. Is preferred. It is preferable to add the fine particles by external addition in order to improve toner transferability. Further, in the present invention, it is particularly preferable for improving the cleaning property of the photoreceptor.
The fine particles used in the present invention preferably have a number average particle size of 60 nm to 300 nm, more preferably 80 nm to 200 nm. Among these, spherical silica particles having a size of 100 nm or more and 150 nm or less are particularly preferable. If the number average particle size is smaller than 60 nm, not only will the contribution to improving transferability be reduced, but the effect on the cleaning properties of the photoreceptor will be reduced. On the other hand, when the number average particle diameter exceeds 300 nm, the adhesion of fine particles to the toner particles is deteriorated, which may easily cause a charging failure or contamination around the developing device. Further, there is a possibility of damaging the photosensitive member, and as a result, it becomes a factor of deteriorating the cleaning property.
The addition amount of fine particles having a number average particle diameter of 60 nm or more and 300 nm or less is preferably 0.5 to 4.0 parts by mass, more preferably 0.7 to 2.5 parts by mass with respect to 100 parts by mass of the toner particles. When the amount is less than 0.5 parts by mass, the effect of improving transferability and cleaning property is not obtained so much. On the other hand, if the amount exceeds 4.0 parts by mass, the silica particles may not adhere to the toner, which may easily cause charging failure and contamination around the developing device. The number average particle diameter was obtained by taking a photograph of the surface of the toner particles magnified 100,000 times with a scanning electron microscope FE-SEM (S-4700, manufactured by Hitachi, Ltd.), and using the enlarged photograph, The average particle size was determined by measuring the particle size of the silica particles.

The toner used in the present invention is preferably externally added with a fluidity improver, in addition to the fine particles having a number average particle diameter of 60 nm or more and 300 nm or less. As the fluidity improver, inorganic fine powders such as silicate fine powder, titanium oxide fine powder, and aluminum oxide fine powder are preferable. Furthermore, it is more preferable that it is hydrophobized with a hydrophobizing agent which is a silane coupling agent, silicone oil or a mixture thereof.
The fluidity improver is usually used at a ratio of 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner particles.
In the case of a black toner used in full color image formation, as a fluidity improver,
It is preferable to use titanium oxide fine powder. For mixing the toner particles and the fluidity improver, it is preferable to use a mixer such as a Henschel mixer.

Next, the binder resin used for the toner will be described.
Examples of the binder resin for the toner used in the present invention include the following. Polyester; Polystyrene; Polymer of styrene derivatives such as poly-p-chlorostyrene and polyvinyltoluene; Styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic Acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, Styrene copolymer such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride; phenol resin; modified phenol resin; maleic resin; acrylic resin; methacrylic resin; Polyester resin having as a structural unit a monomer selected from aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohol and diphenol; polyurethane resin; polyamide resin; polyvinyl butyral; terpene Resin; Coumarone indene resin; Petroleum resin.

  Examples of the colorant used in the toner include the following. As the colorant, a pigment may be used alone, but it is more preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using a dye and a pigment together.

  Examples of the black colorant include carbon black; a magnetic material; a color toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

Colorant for magenta toner:
Examples of the magenta toner pigment include the following. C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207.209, 238; I. Pigment violet 19; C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35.
Examples of the magenta toner dye include the following. C. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; C.I. I. Disperse thread 9; C.I. I. Solvent violet 8, 13, 14, 21, 27; C.I. I. Oil-soluble dyes such as Disper Violet 1, C.I. I. B. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

Colorant for cyan toner:
Examples of the cyan toner pigment include the following. C. I. Pigment blue 2, 3, 15: 3, 15: 4, 16, 17; I. Bat Blue 6; C.I. I. Acid Blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton.

Colorant for yellow toner:
Examples of the yellow pigment include the following. C. I. Pigment Yellow 1,
2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; I. Bat yellow 1, 3, 20
Examples of yellow dyes include C.I. I. There is Solvent Yellow 162.

  The amount of the colorant used is preferably 0.1 parts by weight or more and 30 parts by weight or less, more preferably 0.5 parts by weight or more and 20 parts by weight or less, with respect to 100 parts by weight of the binder resin. Most preferably, it is 3 to 15 mass parts.

A known charge control agent can be used for the toner in order to stabilize its chargeability. Although the charge control agent varies depending on the type of charge control agent and the physical properties of other toner constituent materials, it is preferably contained in an amount of 0.2 to 10 parts by mass per 100 parts by mass of the binder resin in the toner. . As such a charge control agent, there are known one that controls the toner to be negatively charged and one that controls the toner to be positively charged. The above can be used.
Examples of the negatively chargeable (negative) charge control agent include salicylic acid metal compounds, naphthoic acid metal compounds, dicarboxylic acid metal compounds, polymer compounds having sulfonic acid or carboxylic acid in the side chain, boron compounds, urea compounds, Examples thereof include silicon compounds and calixarene.
Examples of the positively chargeable (positive) charge control agent include quaternary ammonium salts, polymer compounds having the quaternary ammonium salt in the side chain, guanidine compounds, and imidazole compounds. Among these, a metal compound of an aromatic carboxylic acid that is colorless and has a high toner charging speed and can stably maintain a constant charge amount is particularly preferable. The charge control agent may be added internally or externally to the toner particles.

The toner can be obtained by a suspension polymerization method, an emulsion aggregation method, an association polymerization method, a kneading and pulverization method, and the production method is not particularly limited.
Hereinafter, an example of a method for producing the toner will be described. In the raw material mixing step, a toner resin composition is obtained by weighing and blending and mixing a predetermined amount of a binder resin and a release agent, and optionally other materials, as materials constituting the toner particles. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.
In order to form the toner particle composition, it is melt kneaded to melt the resin, and a release agent or the like is dispersed therein. In the melt kneading step, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. Due to the advantage of continuous production, single or twin screw extruders are the mainstream. KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd. A twin screw extruder manufactured by Kay Sea Kay Co. and a co-kneader manufactured by Buss can be used.
Furthermore, the composition obtained by the melt kneading is rolled by a two-roll or the like and cooled through a cooling step of cooling by water cooling or the like. The cooled product is then ground to the desired particle size in a grinding process. In the pulverization process, coarse pulverization is performed by a crusher such as a crusher, hammer mill, or feather mill. Furthermore, a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a super rotor manufactured by Nisshin Engineering, a turbo mill manufactured by Turbo Industry (RSS rotor) / SNNB liner) or air jet type fine pulverizer.
After that, if necessary, classification is performed using a classifier such as an inertia class elbow jet (manufactured by Nippon Steel Mining Co., Ltd.) or centrifugal class turboplex (manufactured by Hosokawa Micron Co., Ltd.) or a sieving machine, and the weight average particle diameter ( Toner particles having D4) of 3 μm or more and 11 μm or less are obtained.
If necessary, the toner particles can be subjected to surface modification such as spheroidization using a hybridization system manufactured by Nara Machinery Co., Ltd. or a mechano-fusion system manufactured by Hosokawa Micron Corporation.

The toner used in the present invention has an average circularity of 0.930 or more, measured by a flow type particle image measuring apparatus having an image processing resolution of 512 × 512 pixels (0.37 μm × 0.37 μm per pixel), 0 Preferably less than 970. The average circularity is the circularity of particles measured by a flow type particle image measuring apparatus having a field of view of 512 pixels × 512 pixels and a resolution of 0.37 μm × 0.37 μm per pixel. This is based on the circularity distribution analyzed by dividing the degree range of 0.2 to 1.0 into 800 divided channels.
When the average circularity of the toner is less than 0.930, the contact area between the toners and between the toner and the magnetic carrier is increased, which may hinder the separation of the toner from the magnetic carrier and lower the image density. On the other hand, when the average circularity is 0.970 or more, the shape is too spherical, and the transfer residual toner may pass through the cleaning blade in a high speed machine, resulting in poor cleaning.

In the present invention, the following method can be preferably exemplified in order to adjust the average circularity of the toner within the above range. In other words, this is a technique of applying a mechanical impact force while discharging fine powder generated in the production of toner particles out of the system.
In order to adjust the average circularity of the toner within the above-mentioned range, processing (giving mechanical impact force) while discharging the fine powder generated in the pulverization step and / or the surface modification step of the spheroidization treatment to the outside of the system ) Is preferably performed. FIG. 1 is a schematic cross-sectional view showing an example of a surface modification apparatus capable of performing the above-described treatment while discharging fine powder out of the system. The surface modification apparatus of FIG. 1 is composed of the following members. A main body casing 30, a cooling jacket 31 through which cooling water or antifreeze liquid can be passed, and a disk-shaped rotating body that has a plurality of square disks 33 on the upper surface and is attached to the central rotating shaft in the casing 30, and rotates at high speed. The dispersion rotor 32 as a surface modification means, and a liner 34 provided with a large number of grooves on the surface and arranged on the outer periphery of the dispersion rotor 32 (there is no groove on the liner surface) A classification rotor 35 that is a means for classifying the surface-modified raw material into a predetermined particle size, a cold air inlet 46 for introducing cold air, and a raw material supply port for introducing the raw material to be treated 39, a product discharge valve 41 installed so as to be openable and closable so that the surface modification time can be freely adjusted, a product discharge port 40 for discharging processed powder, and a classification rotor 3 And the first rotor 47 before being introduced into the classification rotor 35, and the first space 47 for introducing the particles from which fine powder has been removed by the classification means into the surface treatment means. A cylindrical guide ring 36 as a guide means for partitioning into a second space 48. A gap portion between the dispersion rotor 32 and the liner 34 is a surface modification zone, and the classification rotor 35 and its peripheral portion are classification zones.

In the surface reforming apparatus, when a finely pulverized product is introduced from the raw material supply port 39 with the product discharge valve 41 closed, the charged finely pulverized product is first sucked by a blower (not shown), and is classified by the classification rotor 35. Classified. At that time, the classified fine powder having a predetermined particle diameter or less is continuously discharged out of the apparatus, and the coarse powder having a predetermined particle diameter or more passes along the inner periphery (second space 48) of the guide ring 36 by centrifugal force. The circulating flow generated by the dispersion rotor 32 is guided to the surface modification zone.
The raw material guided to the surface modification zone is subjected to a surface modification treatment by receiving a mechanical impact force between the dispersion rotor 32 and the liner 34. The surface-modified particles having undergone surface modification are guided to the classification zone along the outer periphery (first space 47) of the guide ring 36 by the cold air passing through the machine. The fine powder generated at this time is again discharged out of the machine by the classification rotor 35, and the coarse powder is returned to the surface modification zone again through the circulation flow, and repeatedly undergoes the surface modification action. After a certain period of time, the product discharge valve 41 is opened and the surface modified particles are recovered from the product discharge port 40.

As a result of investigations by the present inventors, in the surface modification step using the surface modification device, the time (cycle time) from the introduction of the finely pulverized product from the raw material supply port 39 to the product discharge valve opening and the dispersion rotor It has been found that the rotation speed is important in controlling the sphericity of the toner and the amount of the release agent on the toner particle surface (that is, the toner transmittance).
In order to increase the sphericity, it is effective to increase the cycle time or increase the peripheral speed of the dispersion rotor. In order to keep the amount of the release agent on the toner particle surface low, it is effective to shorten the cycle time or lower the peripheral speed. In particular, the toner cannot be efficiently spheroidized unless the peripheral speed of the dispersion rotor exceeds a certain level. Therefore, the cycle time must be increased to spheroidize, and the amount of surface release agent must be increased more than necessary. May end up. In order to improve the circularity of the toner and keep the average circularity of the toner within the above range while suppressing the amount of the release agent on the toner particle surface to a predetermined value or less, the peripheral speed of the dispersion rotor is set to 1.2 × 10 ⁵ mm. It is effective to set the cycle time to 15 to 60 seconds.

    In the two-component developer of the present invention, the mixing ratio of the toner and the magnetic carrier is in the range of 0.02 parts by mass to 0.35 parts by mass with respect to 1 part by mass of the magnetic carrier. It is preferably 0.04 parts by mass or more and 0.25 parts by mass or less, more preferably 0.05 parts by mass or more and 0.20 parts by mass or less. If it is less than 0.02 parts by mass, the image density tends to be low, and if it exceeds 0.35 parts by mass, fog and in-machine scattering are likely to occur.

The replenishment developer of the present invention is characterized by containing at least the toner and the magnetic carrier. The replenishment developer is used for a two-component developer method in which the replenishment developer is developed while being replenished to the developing device, and at least the excess magnetic carrier inside the developing device is discharged from the developing device. Features.
The replenishment developer contains the toner in an amount of 2 parts by mass or more and 50 parts by mass or less with respect to 1 part by mass of the magnetic carrier from the viewpoint of enhancing the durability of the developer. .
In the above replenishment developer, when the toner content is less than 2 parts by mass with respect to 1 part by mass of the magnetic carrier, a large amount of replenishment developer is replenished particularly when an image having a high printing density is printed at high speed. Is required. As a result, the developer for replenishment and the developer in the developing device are used for development before being sufficiently mixed, and the toner tends to be non-uniformly charged. As a result, the image quality may deteriorate. In addition, the amount of developer discharged is increased.
If the toner is contained in an amount of more than 50 parts by mass with respect to 1 part by mass of the magnetic carrier, the deteriorated magnetic carrier may be used for a long time without being discharged, and the deterioration of the magnetic carrier may progress and the image may be lowered.
In addition, the toner and the magnetic carrier used for the two-component developer (hereinafter also referred to as start developer) and the replenishment developer that are initially filled in the developer are the same or different. It doesn't matter.

The two-component developer includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. It is used for an image forming apparatus using a photoconductor provided with a surface protective layer containing at least one selected.
The image forming method of the present invention also includes a developer carrying a conductive substrate, a photoreceptor having at least a photoconductive layer on the conductive substrate, and a two-component developer containing a magnetic carrier and toner. In the image forming method, the photoconductor is disposed on a surface of the photoconductive layer, and the photoconductive layer includes at least one selected from the group consisting of amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. The magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles, and the porous magnetic core particles have a solid apparent density of ρ1 (g / g). cm ^3), when the true density ^{ρ2 (g / cm 3),} ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.2 Or more and 0.42 or less, the specific resistance of the porous magnetic core particles, 1.0 × 10 ³ Ω · cm or more, or less 5.0 × 10 ⁷ Ω · cm, the specific resistance of the magnetic carrier, 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less, and the toner contains at least a binder resin and a release agent, and is measured by a differential scanning calorimeter (DSC). The endothermic curve has one or a plurality of endothermic peaks in the temperature range of 30 ° C. or higher and 200 ° C. or lower, and the peak temperature of the endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower. And
The photoconductor is a so-called amorphous silicon photoconductor (hereinafter also referred to as “a-Si photoconductor”) having a conductive substrate and a photoconductive layer formed to contain at least amorphous silicon on the conductive substrate. Various conventionally known a-Si photoreceptors can be used.
In the present invention, a commonly used aluminum cylindrical body can be used for the conductive substrate, but it is not particularly limited to this form. In the present invention, the photoconductive layer may be a single layer or may be formed of a laminate of a plurality of layers. The photoconductive layer can contain an appropriate amount of atoms other than silicon, such as oxygen, carbon, nitrogen, hydrogen, halogen, Group 13 element, Group 15 element, and the like.
In the present invention, layers other than the photoconductive layer may be formed as necessary. Examples of such a layer include a charge injection blocking layer formed between a conductive substrate and a photoconductive layer.
The above photoreceptor can be produced by various conventionally known methods. Examples of such a production method include, for example, a raw material containing desired atoms in a depressurized reaction vessel that contains and supports a conductive substrate. A plasma CVD method in which a gas (for example, SiH ₄ or the like) is introduced, the source gas is decomposed in the reaction vessel by glow discharge, and a film is formed on the surface of the conductive substrate supported in the reaction vessel is preferably exemplified.
In the present invention, the photosensitive member is charged by a charging unit, an electrostatic latent image is formed on the charged photosensitive member by a latent image forming unit, the formed electrostatic latent image is developed by a developer, and a toner image formed is formed. Transfer to transfer material by transfer means. As the charging means, various conventionally known charging means can be used. As such a charging means, for example, a contact charging means having a contact charging member such as a charging roller having conductivity and elasticity is preferably cited. It is done.

  A method for measuring various physical properties of the magnetic carrier and toner will be described below.

<Method for removing porous magnetic core particles>
The porous magnetic core particles can be taken out from the magnetic carrier by the following method as needed.
10.0 g of a magnetic carrier is prepared and placed in a crucible. Using a muffle furnace (FP-310, manufactured by Yamato Kagaku) equipped with an N ₂ gas inlet and an exhaust device unit, heating was performed at 900 ° C. for 16 hours while introducing N ₂ gas. After heating, it was left until the temperature of the magnetic carrier reached 50 ° C. or lower. Thereafter, the heated magnetic carrier was placed in a 50 cc plastic bottle, 0.2 g of sodium dodecylbenzenesulfonate and 20 g of water were added, and soot and the like adhering to the magnetic carrier were washed. At this time, the magnetic carrier was fixed with a magnet so as not to flow. Moreover, it wash | cleaned 5 times or more with water so that sodium dodecylbenzenesulfonate may not remain in a magnetic carrier. Then, it was dried at 60 ° C. for 24 hours.
As described above, porous magnetic core particles were taken out from the magnetic carrier. In addition, said operation was performed in multiple times and the required amount of the porous magnetic core particle was ensured.

<Solid apparent density of porous magnetic core particles>
Using the porous magnetic core particles taken out as described above, the solid apparent density was measured using a powder tester PT-R (manufactured by Hosokawa Micron Corporation).
Using a sieve with an opening of 500 μm, while vibrating with an amplitude of 1 mm, while replenishing the porous magnetic core particles until just 10 ml, the metal cup was tapped 180 times up and down at an amplitude of 18 mm, and after tapping, From the amount of the porous magnetic core particles, the apparent solid density (g / cm ³ ) was calculated.

<True density of porous magnetic core particles>
The true density of the porous magnetic core particles was measured with a dry automatic densimeter autopycnometer (manufactured by Yuasa Ionics). The measurement conditions are as follows.
(Measurement condition)
Cell SM cell (10ml)
Sample amount 2.0g
This measurement method measures the true density of a solid / liquid based on a gas phase substitution method. Similar to the liquid phase replacement method, it is based on Archimedes' principle, but uses a gas (argon gas) as a replacement medium, and therefore has high accuracy for micropores.

<Resistivity of porous magnetic core particles and magnetic carrier>
The specific resistance of the porous magnetic core particles and the magnetic carrier was measured using a measuring apparatus schematically shown in FIG. The resistance measurement cell E is filled with the porous magnetic core particles or the magnetic carrier (17), and the lower electrode (11) and the upper electrode (12) are arranged so as to be in contact with the filled porous magnetic core particles or the magnetic carrier, A specific resistance of the porous magnetic core particle or carrier was determined by applying a voltage between these electrodes and measuring the current flowing at that time.
The measurement conditions for the specific resistance of the porous magnetic core particle were a contact area S of the porous magnetic core particle and the electrode of S = 2.4 cm ² and a load of the upper electrode of 240 g. A sample amount of 10.0 g was measured, the sample was filled in a resistance measurement cell, and the thickness d of the sample was accurately measured. The voltage application conditions were applied in the order of application conditions I, II, and III, and the current at the applied voltage in application condition III was measured. Thereafter, the specific resistance (Ω · cm) at each electric field strength (V / cm) was obtained by the following formula. The specific resistance at the electric field intensity of 100 V / cm under the application condition III (that is, when the applied voltage / d = 100 (V / cm)) was defined as the specific resistance of the porous magnetic core particles.

Application condition I: (Changed from 0V to 500V: Increase in steps of 100V every 30 seconds)
II: (Hold for 30 seconds at 500V)
III: (Change from 500V to 0V: Decrease in steps of 100V every 30 seconds)

The measurement conditions for the specific resistance of the magnetic carrier were a contact area S = 2.4 cm ² between the magnetic carrier and the electrode, and a load of 240 g on the upper electrode. A sample amount of 1.0 g was measured, the sample was filled in a resistance measurement cell, and the thickness d of the sample was accurately measured. The voltage application conditions were applied in the order of application conditions I, II, and III, and the current at the applied voltage in application condition III was measured. Thereafter, the specific resistance (Ω · cm) at each electric field strength (V / cm) was obtained by the following formula. The specific resistance at the electric field strength of 3000 V / cm under the application condition III (that is, when the applied voltage / d = 3000 (V / cm)) was defined as the specific resistance of the magnetic carrier.

Application condition I: (Changed from 0V to 1000V: Increased in steps of 200V every 30 seconds)
II: (Hold for 30 seconds at 1000V)
III: (Change from 1000V to 0V: Decrease in steps of 200V every 30 seconds)

Formula): specific resistance (Ω · cm) = (applied voltage (V) / measured current (A)) × S (cm ² ) / d (cm)

In the above formula, the value of “applied voltage (V) / d (cm)” is 100 (V / cm) in the measurement of the porous magnetic core particles, and 3000 (V / cm) in the measurement of the carrier. is there.

<Toner endothermic peak number and maximum endothermic peak temperature>
The maximum endothermic peak number of the toner and the peak endothermic peak temperature are determined by using a differential scanning calorimeter (DSC measuring apparatus) DSC2920 (manufactured by TA Instruments Japan) and ASTM.
According to D3418-82, the measurement was performed under the following conditions.

Temperature curve: Temperature increase I (30 ° C. to 200 ° C., temperature increase rate 10 ° C./min)
Temperature drop I (200 ° C-30 ° C, temperature drop rate 10 ° C / min)
Temperature increase II (30 ° C. to 200 ° C., temperature increase rate 10 ° C./min)

The measurement sample is precisely weighed in an amount of 3 to 7 mg, preferably 4 to 5 mg. Put it in an aluminum pan, use an empty aluminum pan as a reference, and measure at a temperature rise rate of 10 ° C / min at a temperature range of 30-200 ° C and at normal temperature and humidity (23 ° C / 50% RH). Went.
The number of endothermic peaks is the number of peak tops in the process of temperature increase II. The peak temperature of the maximum endothermic peak was set to the temperature showing the top of the peak with the highest endotherm among the peaks in the process of temperature increase II.

<50% particle size based on volume distribution of porous magnetic core particle or magnetic carrier (D50)>
The volume distribution standard 50% particle size (D50) of the porous magnetic core particle or magnetic carrier was measured using a multi-image analyzer (manufactured by Beckman Coulter, Inc.) as follows.
A solution obtained by mixing a 1% NaCl aqueous solution and glycerin at 50% by volume: 50% by volume was used as an electrolytic solution. Here, the NaCl aqueous solution may be prepared using primary sodium chloride, and may be, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan). Glycerin may be a special grade or first grade reagent.
To the electrolytic solution (about 30 ml), 0.5 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) was added as a dispersant, and 10 mg of a measurement sample was further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute to obtain a dispersion.
Using a 200 μm aperture and a 20 × lens as the aperture, the equivalent circle diameter was calculated under the following measurement conditions.

Average luminance within measurement frame: 220 to 230
Measurement frame setting: 300
SH (threshold): 50
Binarization level: 180

The electrolytic solution and the dispersion liquid were put in a glass measuring container, and the concentration of the porous magnetic core particles or the magnetic carrier particles in the measuring container was set to 10% by volume. The contents of the glass measuring container were stirred at the maximum stirring speed. The sample suction pressure was 10 kPa. When the specific gravity of the porous magnetic core particles or the magnetic carrier particles is large and easily settles, the measurement time is set to 20 minutes. In addition, the measurement was interrupted every 5 minutes to replenish the sample solution and the electrolytic solution-glycerin mixed solution.
The number of measurements was 2000. After the measurement was completed, the main body software was used to remove defocused images, aggregated particles (multiple simultaneous measurements), etc. on the particle image screen.
The equivalent circle diameter of the porous magnetic core particle or magnetic carrier was calculated by the following formula.

Equivalent circle diameter = (4 · Area / π) ^1/2

Here, “Area” is the projected area of the binarized particle image. The equivalent circle diameter is "Ar
It is represented by the diameter of a perfect circle when “ea” is the area of the perfect circle. The obtained circle equivalent diameters were each divided into 4 to 100 μm in 256 and expressed in a logarithmically expressed graph based on volume, thereby obtaining a 50% particle size (D50) based on volume distribution.

<Average circularity of toner, etc.>
The average circularity of the toner or the like was measured with a flow type particle image analyzer “FPIA-3000 type” (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration operation.
The measurement principle of the flow-type particle image analyzer “FPIA-3000 type” (manufactured by Sysmex Corporation) is to take a flowing particle as a still image and perform image analysis. The sample added to the sample chamber is fed into the flat sheath flow cell by a sample suction syringe. The sample fed into the flat sheath flow is sandwiched between sheath liquids to form a flat flow. The sample passing through the flat sheath flow cell is irradiated with strobe light at 1/60 second intervals, and the flowing particles can be photographed as a still image. Further, since the flow is flat, the image is taken in a focused state. The particle image is captured by a CCD camera, and the captured image is subjected to image processing at an image processing resolution of 512 × 512 (0.37 × 0.37 μm per pixel), and the contour of each particle image is extracted, Projected area, perimeter, etc. are measured.
Next, the projected area S and the perimeter L of each particle image are obtained. Using the area S and the perimeter L, the equivalent circle diameter and the circularity are obtained. The equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particle image. Defined and calculated by the following formula.

Circularity C = 2 × (π × S) ^1/2 / L

When the particle image is a perfect circle, the circularity becomes 1.000, and the circularity becomes smaller as the degree of irregularities on the outer periphery of the particle image increases.
After calculating the circularity of each particle, the range of the circularity of 0.2 to 1.0 is divided into 800, and the average circularity is calculated using the number of measured particles.
As a specific measurement method, 0.02 g of a surfactant, preferably an alkylbenzene sulfonate, is added to 20 ml of ion-exchanged water, and then 0.02 g of a measurement sample is added, an oscillation frequency of 50 kHz, electrical output. Dispersion treatment was performed for 2 minutes using a 150 W tabletop type ultrasonic cleaner disperser (for example, “VS-150” (manufactured by Velvo Crea Co., Ltd.)) to obtain a dispersion for measurement. It cooled suitably so that temperature might be 10 to 40 degreeC.
For the measurement, the above-mentioned flow type particle image analyzer equipped with a standard objective lens (10 ×) was used, and a particle sheath “PSE-900A” (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion prepared according to the above procedure is introduced into the flow type particle image analyzer, 3000 toner particles are measured in the total count mode in the HPF measurement mode, and the binarization threshold at the time of particle analysis is 85%. The analysis particle diameter was limited to a circle equivalent diameter of 2.00 μm to 200.00 μm, and the average circularity of the toner was determined.
In the measurement, automatic focus adjustment was performed using standard latex particles (for example, Duke Scientific 5200A diluted with ion-exchanged water) before the measurement was started. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement.
In the examples of the present application, a flow type particle image analyzer that has been issued a calibration certificate issued by Sysmex Corporation is used, and the analysis particle diameter is limited to a circle equivalent diameter of 2.00 μm or more and 200.00 μm or less. Measured under the measurement and analysis conditions when the calibration certificate was received.

<Measurement of weight average particle diameter (D4) of toner, etc.>
The weight average particle diameter (D4) of the toner or the like is measured using a Coulter counter TA-II type (manufactured by Coulter), but a Coulter multisizer (manufactured by Coulter) can also be used. A specific measurement method is described below.
As the electrolytic solution, a 1% NaCl aqueous solution was prepared using first grade sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. In 100 ml of the electrolytic aqueous solution, 0.1 g of a surfactant, preferably an alkyl benzene sulfonate, was added as a dispersant, and 5 mg of a measurement sample was further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion process for 2 minutes with an ultrasonic disperser, and the volume and number of toner particles of 2.00 μm or more are measured by using the 100 μm aperture as an aperture with the above measuring apparatus. Distribution was calculated. Using the calculation results, the weight average particle size (D4) (the median value of each channel is used as the representative value for each channel) was determined.
As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32.00-40.30 μm were used.

<Measurement of molecular weight distribution by gel permeation chromatograph (GPC)>
The molecular weight distribution of the chromatogram by gel permeation chromatograph (GPC) was measured under the following conditions.
The column is stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min. The sample solution was measured by injecting 100 μm. An RI (refractive index) detector was used as the detector. As the column, in order to accurately measure a molecular weight region of 1 × 10 ³ or more and 2 × 10 ⁶ or less, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, μ-styragel 500, 103 manufactured by Waters , 104, 105, and combinations of shodex KA-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko KK are preferable.
In measuring the molecular weight distribution of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Manufactured by Toyo Soda Kogyo Co., Ltd., with molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , It is appropriate to use 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples.

Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

[Production Example 1 of Porous Magnetic Core Particles]
<1. Weighing and mixing process>
Fe ₂ O ₃ 66.5 mass%
MnCO ₃ 28.1% by mass
Mg (OH) ₂ 4.8% by mass
SrCO ₃ 0.6% by mass
Then, water was added to the ferrite raw material and wet-mixed with a ball mill.

<2. Temporary firing process>
After drying and grinding, it was fired at 900 ° C. for 2 hours to produce ferrite.

<3. Grinding process>
After crushing to about 0.1 to 1.0 mm with a crusher, water was added and finely pulverized to 0.1 to 0.5 μm with a wet ball mill to obtain a ferrite slurry.

<4. Granulation process>
5% by mass of polyester fine particles (weight average particle diameter D4 is 2 μm) as a pore-forming agent and 2% by mass of polyvinyl alcohol as a binder are added to the ferrite slurry, and the particles are made into spherical particles with a spray dryer (manufacturer: Okawara Chemical Industries). Grained.

<5. Firing step>
In an electric furnace, firing was performed at 1200 ° C. for 4 hours in a nitrogen atmosphere having an oxygen concentration of 1.0%, and further, firing was performed at 750 ° C. for 30 minutes in a nitrogen atmosphere not containing oxygen.

<6. Sorting process 1>
The coarse particles were removed by sieving with a sieve having an opening of 250 μm.

<7. Sorting process 2>
Classification was carried out with an air classifier (Elbow Jet Lab EJ-L3, manufactured by Nippon Steel Mining Co., Ltd.) to obtain porous magnetic core particles 1.

[Production Example 2 of Porous Magnetic Core Particles]
Porous magnetic core particles were produced in the same manner as in Production Example 1 of porous magnetic core, except that firing was carried out in an electric furnace in a nitrogen gas atmosphere with an oxygen gas concentration of 1.5% at 1150 ° C. for 4 hours. Core particle 2 was obtained.

[Production Example 3 of Porous Magnetic Core Particle]
Among the production examples 1 of porous magnetic core particles, porous magnetic core particles 3 were obtained in the same manner except that the following <Firing step 2> was performed between the firing step and the selection step 1.
<Baking step 2>: Baking was performed at 800 degrees for 1 hour in a nitrogen atmosphere.

[Production Examples 4, 5, and 6 of Porous Magnetic Core Particles]
In Production Example 1 of porous magnetic core particles, porous magnetic core particles 4 were obtained in the same manner except that the addition amount of the polyester fine particles was changed from 5 mass% to 3 mass% in the granulation step.
Among the production examples 1 of the porous magnetic core particles, in the granulation step, the addition amount of the polyester fine particles was changed from 5% by mass to 10% by mass, and the addition amount of the polyvinyl alcohol was changed from 2% by mass to 4% by mass. Similarly, porous magnetic core particles 5 were obtained.
Among the production examples 1 of the porous magnetic core particles, in the granulation step, the addition amount of the polyester fine particles was changed from 5 mass% to 20 mass%, and the addition amount of the polyvinyl alcohol was changed from 2 mass% to 7 mass%. Similarly, porous magnetic core particles 6 were obtained.

[Production Example 7 of porous magnetic core particles]
Among the production examples 1 of porous magnetic core particles, the amount of polyester fine particles added was changed from 5% by mass to 1% by mass in the granulation step, and the oxygen gas concentration was 0.5% in the electric furnace in the firing step A porous magnetic core particle 7 was obtained in the same manner except that it was calcined at 1100 ° C. for 4 hours in a nitrogen gas atmosphere.

[Production Example 8 of Porous Magnetic Core Particles]
Among the production examples 1 of porous magnetic core particles, in the weighing and mixing step,
Fe ₂ O ₃ 69.0 mass%
ZnO 16.0% by mass
CuO 15.0 mass%
The porous magnetic core particles 8 were obtained in the same manner except that the ferrite raw material was used. Table 1 shows the physical properties of the porous magnetic core particles.

[Production Example 1 of magnetic core particles]
As the magnetic core particles, spherical iron powder having physical properties as shown in Table 1 was used. The above was designated as magnetic core particle 1.

[Production Example 1 of Magnetic Carrier]
<1. Resin liquid preparation process>
Dimethyldiethoxysilane / methyltriethoxysilane / tetraethoxysilane = 7 mol / 2 mol / 1 mol co-condensation polymer 10.5 mass%
γ-aminopropyltriethoxysilane 0.5% by mass
Xylene 89.0% by mass
The above was mixed and the resin liquid 1 was obtained.
Similarly, dimethyldiethoxysilane / methyltriethoxysilane / tetraethoxysilane = 7 mol / 2 mol / 1 mol copolycondensation product 21.0% by mass
γ-aminopropyltriethoxysilane 1.0% by mass
Xylene 78.0% by mass
The above was mixed and the resin liquid 2 was obtained.

<2. Resin-containing process 1>
The porous magnetic core particle 1 was put into a universal stirrer (5XDML: manufactured by Dalton Co., Ltd.), the temperature was set to 60 ° C., and the porous magnetic core particle 1 was stirred until the porous magnetic core particle 1 reached 60 ° C. Thereafter, the resin liquid 1 was dropped at a rate of 8 ml / min so that the silicone resin was 8% by mass with respect to the porous magnetic core particles, and the porous magnetic core particles 1 were allowed to contain a resin.

<3. Drying process 1>
Xylene was removed by heating at 60 ° C. for 5 hours.

<4. Curing process 1>
The resin was cured by heating at 180 ° C. for 3 hours.

<5. Resin-containing process 2>
After setting the temperature in the tank to 70 ° C. using a universal stirrer, the resin liquid 2 in an amount of 11% by mass of the silicone resin with respect to the porous magnetic core particles is dropped at a rate of 20 ml / min to contain the resin. I let you.

<6. Drying process 2>
Xylene was removed by heating at 80 ° C. for 5 hours.

<7. Curing process 2>
The resin was cured by heating at 220 ° C. for 3 hours.

<8. > The steps <5>, <6>, and <7> were repeated once again to coat the porous magnetic core particles 1 with a resin.

<9. Sieve process>
Sieve shaker (300MM-2 type, Tsutsui physics and chemistry opportunity sieved with 75 μm opening to obtain magnetic carrier 1. Table 2 shows the physical properties of the magnetic carrier.

[Production Examples 2, 3, 4, 5, 8, 9, 10, 11 of magnetic carrier]
<2. In the resin containing step 1>, the magnetic carriers 2 to 5 and 8 to 11 are obtained in the same manner as in the magnetic carrier production example 1 except that the following porous magnetic core particles are used instead of the porous magnetic core particles 1. It was.
Magnetic carrier 2: porous magnetic core particle 2
Magnetic carrier 3: porous magnetic core particle 3
Magnetic carrier 4: porous magnetic core particle 4
Magnetic carrier 5: Porous magnetic core particle 5
Magnetic carrier 8: porous magnetic core particle 6
Magnetic carrier 9: Porous magnetic core particle 7
Magnetic carrier 10: porous magnetic core particle 8
Magnetic carrier 11: magnetic core particle 1

[Production Example 6 of Magnetic Carrier]
<2. In the resin-containing step 1>, the resin liquid 1 was contained in the porous magnetic core particles so that the silicone resin was 11% by mass with respect to the porous magnetic core particles.
In addition, <5. In the resin containing step 2>, the resin liquid 2 was contained in the porous magnetic core particles so that the silicone resin was 12% by mass with respect to the porous magnetic core particles. Except for these, the magnetic carrier 6 was obtained in the same manner as in Magnetic Carrier Production Example 2.

[Magnetic Carrier Production Example 7]
<2. In the resin-containing step 1>, the resin liquid 1 was contained in the porous magnetic core particles so that the silicone resin was 7% by mass with respect to the porous magnetic core particles.
In addition, <5. In the resin-containing step 2>, the resin liquid 2 was contained in the porous magnetic core particles so that the silicone resin was 9% by mass with respect to the porous magnetic core particles. Except for these, the magnetic carrier 7 was obtained in the same manner as in Magnetic Carrier Production Example 3.

[Production Example 12 of Magnetic Carrier]
In Production Example 1 of the magnetic carrier, the porous magnetic core particle was changed to 8, and <5. Resin-containing step 2>, <6. Drying step 2> and <7. A magnetic carrier 12 was obtained in the same manner as in Magnetic Carrier Production Example 1 except that the curing step 2> was repeated once more.

Table 2 shows the physical properties of the magnetic carrier.

[Example of binder resin production]
As a material for the vinyl polymer unit, 2.0 mol of styrene, 0.21 mol of 2-ethylhexyl acrylate, 0.14 mol of fumaric acid, 0.03 mol of α-methylstyrene dimer and 0.05 mol of dicumyl peroxide were added to a dropping funnel. Put it in. As a material of the polyester unit, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) ) 3.0 mol of propane, 3.0 mol of terephthalic acid, 1.9 mol of trimellitic anhydride, 5.0 mol of fumaric acid and 0.2 g of dibutyltin oxide were put into a 4-liter four-necked flask made of glass. A thermometer, a stirring rod, a condenser, and a nitrogen introduction tube were attached to the four-necked flask, and the four-necked flask was placed in a mantle heater. Next, after the inside of the four-necked flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and the monomer and polymerization of the vinyl polymer unit were performed from the previous dropping funnel while stirring at a temperature of 145 ° C. The initiator was added dropwise over 6 hours. Next, the obtained product was heated to 200 ° C. and reacted for 6 hours to obtain a hybrid resin 1. Regarding the molecular weight of this hybrid resin 1 by GPC, the weight average molecular weight (Mw) was 145000, the number average molecular weight (Mn) was 4500, and the peak molecular weight was 15500.

<Dispersion of release agent dispersant and release agent in binder resin>
Copolymer resin (I) 90 parts by mass Polyethylene (Mw: 10000, Mn: 2000) 10 parts by mass

The copolymer resin (I) is a terpolymer of styrene (83.0 mol%), acrylonitrile (7.0 mol%), monobutyl maleate (10.0 mol%). The release resin dispersant was obtained by grafting the copolymer resin (I) to polyethylene at the above blending ratio.

Release agent dispersant 25 parts by weight Purified normal paraffin (DSC maximum endothermic peak 70 ° C.) 50 parts by weight Hybrid resin 1 25 parts by weight

First, the above raw materials are charged into a kneader-type mixer, and the temperature is raised under no pressure while mixing. The material itself was heated and melt-kneaded at 100 ° C. for 10 minutes, cooled and pulverized easily to obtain a kneaded product 1.

[Toner Production Example 1]
-Hybrid resin 1 90 mass parts-Kneaded material 1 10 mass parts-C.I. I. Pigment Blue 15: 3 7 parts by mass After the above materials were thoroughly mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a twin-screw kneader (PCM-30 type, Ikegai set at a temperature of 130 ° C.) Kneading was carried out by Iron Works Co., Ltd. The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely crushed material was finely pulverized using a collision-type airflow pulverizer using high-pressure gas. The obtained finely pulverized product had a weight average particle diameter (D ₄ ) of 4.9 μm and an average circularity of 0.915.
Next, the obtained finely pulverized product is put into the surface reforming apparatus at a rate of 1.3 kg per time using the surface modifying apparatus shown in FIG. 1, and the number of rotations of the classification rotor 35 is set to 7300 rpm to remove fine particles. However, the surface treatment was performed for 70 seconds at a rotational speed of the dispersion rotor 32 of 5800 rpm (rotational peripheral speed 130 m / sec). The valve 41 was opened and taken out as a processed product).
At this time, in this embodiment, ten square disks 33 are installed on the upper part of the dispersion rotor 32, the distance between the guide ring 36 and the square disk 33 on the dispersion rotor 32 is 30 mm, and the dispersion rotor 32 and the liner 34 are arranged. Was set at 5 mm. The blower air volume was 14 m ³ / min, the temperature of the refrigerant passed through the jacket and the cold air temperature T1 were −20 ° C.
As a result of repeated operation for 20 minutes in this state, the temperature T2 behind the classification rotor 35 was stabilized at 27 ° C.
Furthermore, using a mesh surface fixed wind sieve high voltor (NR-300, manufactured by Shin Tokyo Machine Co., Ltd .: air brush attached to the back of the wire mesh), this has a diameter of 30 cm, an opening of 29 μm, and an average diameter of the wire Was provided with a wire mesh of 30 μm, and the toner particles were supplied to the wire mesh with an air flow of 5 Nm ³ / min to obtain toner particles from which coarse particles were separated.
To 100 parts by mass of the obtained toner particles, 1.0 part by mass of a titanium oxide fine powder having a number average particle diameter of 40 nm and hydrophobized as inorganic fine particles and a number average particle diameter of 110 nm and hydrophobized 1 Toner 1 was obtained by externally adding and mixing 5 parts by mass of spherical amorphous silica fine powder.

[Toner Production Example 2]
In Toner Production Example 1, 90 parts by mass of the hybrid resin 1 as a binder resin was 77.0% by mass of styrene, 20.4% by mass of acrylic acid-n-butyl, 1.8% by mass of methacrylic acid, 2, 2 -Similar to Toner Production Example 1 except that styrene-acrylic resin 1 produced using 0.8% by mass of bis (4,4-di-t-butylperoxycyclohexyl) propane was changed to 90 parts by mass. Thus, Toner 2 was obtained.
As for the molecular weight of the styrene-acrylic resin 1, the weight average molecular weight (Mw) was 850000, the number average molecular weight (Mn) was 8000, and the peak molecular weight was 12000.

[Toner Production Example 3]
Toner 3 was obtained in the same manner as in Toner Preparation Example 1 except that spherical inorganic silica fine powder of inorganic fine particles was not added in the external addition mixing in Toner Preparation Example 1.

[Toner Production Example 4]
In Toner Production Example 1, the same procedure as in Toner Production Example 1, except that the purified normal paraffin (DSC maximum endothermic peak 70 ° C.) used in kneaded product 1 was changed to normal paraffin (DSC maximum endothermic peak 46 ° C.), Toner 4 was obtained.

[Toner Production Example 5]
In the same manner as in Toner Production Example 1, except that the purified normal paraffin (DSC maximum endothermic peak 70 ° C.) used in kneaded product 1 was changed to polyethylene (DSC maximum endothermic peak 158 ° C.) in Toner Production Example 1. 5 was obtained.

[Toner Production Example 6]
Toner 6 was obtained in the same manner as in Toner Production Example 1, except that purified normal paraffin (DSC maximum endothermic peak 70 ° C.) of kneaded product 1 was not used in Toner Production Example 1.

Table 3 shows the physical properties of Toners 1 to 6.

[Examples 1-9 and Comparative Examples 1-9]
According to the description in Table 4, a two-component developer and a replenishment developer were prepared by combining the magnetic carrier and the toner. The following evaluation was carried out using the two-component developer and the replenishment developer and the following apparatuses (Examples 1 to 9 and Comparative Examples 1 to 9). The results are shown in Tables 5 and 6.
The two-component developer was prepared by mixing a magnetic carrier (90% by mass) and a toner (10% by mass). The replenishment developer used in Example 9 and Comparative Example 9 is a mixture of a magnetic carrier (5% by mass) and a toner (95% by mass) (that is, 19 parts by mass of toner with respect to 1 part by mass of the magnetic carrier). And produced. The other replenishment developer contains 100% by mass of toner.

Next, a commercially available color laser copying machine IRC-6800 (Canon Inc.) was modified so that it could be output under the following conditions. The durability test was performed under the following conditions, and various evaluations were performed before and after the durability test.

conditions:
Printing environment Temperature 23 ° C / Humidity 60RH% (hereinafter “N / N”)
Temperature 23 ° C / Humidity 5RH% (hereinafter “N / L”)
Paper Color laser copier paper (81.4 g / m ² )
(Canon Marketing Japan Inc.)
Image formation speed 65 sheets (A4) / min (modified to be output in cyan single color)
Image Number of printed solid images with 50% image area 100,000 sheets

Except for Example 9 and Comparative Example 9, the discharge port 106 installed in the developing chamber of FIG. 3 was closed to modify the developer so that it was not discharged.
In Comparative Example 3, an oil application mechanism was attached to the fixing device of IRC-6800, and an image was output.

(Dot reproducibility)
After the endurance test of 100,000 sheets in each of the “N / N” and “N / L” environments, a dot image in which one pixel is formed by one dot was created.
The spot diameter of the laser beam of IRC-6800 was adjusted so that the area per dot on paper was 20000 μm ² or more and 25000 μm ² or less, and an image was output.
The output image was measured for an area of 1000 dots using a digital microscope VHX-500 (lens wide range zoom lens VH-Z100, manufactured by Keyence Corporation). The number average (S) of dot areas and the standard deviation (σ) of dot areas were calculated, and the dot reproducibility index was calculated according to the following formula as an index of dot reproducibility.
(Formula): Dot reproducibility index (I) = σ / S × 100
[Evaluation criteria]
A: I is less than 4.0 B: I is 4.0 or more and less than 6.0 C: I is 6.0 or more and less than 8.0 (no problem in practical use)
D: I is 8.0 or more (practical problem)

(Carrier adhesion)
After the endurance test of 100,000 sheets in each of the “N / N” and “N / L” environments, the development voltage was adjusted so that the amount of toner loaded on the paper was 0.1 mg / cm ^2, and a solid image ( 1 cm × 1 cm) was printed with 400 lines. When the toner was developed on the photosensitive drum, the main body was turned off, and the number of magnetic carriers adhering on the photosensitive drum was counted with an optical microscope.
[Evaluation criteria]
A: 3 or less B: 4 or more and 10 or less C: 11 or more and 20 or less (no problem in actual use)
D: 21 or more (problems in actual use)

(Density difference between the leading and trailing edges of the image)
After the endurance test of 100,000 sheets in each of the “N / N” and “N / L” environments, the development voltage is adjusted so that the toner loading on the paper is 0.6 mg / cm ^2. A solid image (3 cm × 5 cm) with an area of 100% was printed with 400 lines. The image density was measured using a Macbeth Densitometer RD918 type (Macbeth Densitometer RD918manufactured by Mcbeth Co.) equipped with an SPI filter.
As for the density of the leading edge of the image, the density of three points at a position of 0.5 cm from the leading edge of the image (the one that was printed first) was measured, and the average value was taken as the leading edge image density. On the other hand, the density at the rear end of the image was measured at three points at a position 0.5 cm from the rear end of the image (the one printed later), and the average value was taken as the density at the rear end of the image. The difference between the “density at the front end of the image” and the “density at the rear end of the image” was obtained.
[Evaluation criteria]
A: 0.00 or more and less than 0.05 B: 0.05 or more and less than 0.10 C: 0.10 or more and less than 0.20 (no problem in actual use)
D: 0.20 or more (problem in actual use)

(Density difference before and after leaving)
After the endurance test of 100,000 sheets in each of the “N / N” and “N / L” environments, the environment was set to “H / H” (30 ° C./80 RH%). The development voltage was adjusted so that the toner loading on the paper was 0.6 mg / cm ² . Under the conditions, a solid image (3 cm × 3 cm) having an image area of 100% was printed with 400 lines. Next, the apparatus was allowed to stand for 24 hours at “H / H” (30 ° C./80 RH%), the same image was printed after 24 hours, and the difference in image density before and after being left for 24 hours was determined. The image density was the same as that used in the above-mentioned “Difference in density between the leading edge and trailing edge”.
[Evaluation criteria]
A: 0.00 or more and less than 0.05 B: 0.05 or more and less than 0.10 C: 0.10 or more and less than 0.20 (no problem in actual use)
D: 0.20 or more (problem in actual use)

(Cleanability evaluation)
The evaluation of the cleaning property was performed by outputting a solid image with an image density of 0.6 mg / cm ² before and after the endurance test of 100,000 sheets in each of the “N / N” and “N / L” environments, and the photoconductor immediately after the toner transfer. A transparent tape (Supertech, manufactured by Lintec Co., Ltd.) is applied to the top (A) and the photoconductor (B) after cleaning after toner transfer, respectively, and a transfer residual toner is collected. (A), (B) A transparent tape from which each transfer residual toner is collected is affixed to the above-mentioned plain paper, measured with an X-Rite color reflection densitometer (Color reflection densitometer X-Rite 404A), and cleaned according to the following formula. Was evaluated.
(Equation): Cleaning efficiency = [1- (Image density by color reflection densitometer of photoconductor (B) after cleaning / Image density by color reflection densitometer on (A) immediately after transfer)] × 100 (%)
[Evaluation criteria]
A: Very good (98% or more)
B: Good (95% to less than 98%)
C: No problem in use (92% to less than 95%)
D: Recognized as dirt on the image (89% to less than 92%)
E: Dirt is very noticeable (less than 89%)

It is a schematic diagram of a surface modification apparatus. It is a schematic block diagram of the apparatus which measures a specific resistance value. It is the schematic of the developing device used in the Example.

Explanation of symbols

11 Lower electrode 12 Upper electrode 13 Insulator 14 Ammeter 15 Voltmeter 16 Constant voltage device 17 Porous magnetic core particle or magnetic carrier 18 Guide ring 30 Main body casing 31 Cooling jacket 32 Dispersion rotor 33 Square disk 34 Liner 35 Classification rotor 36 Guide ring 37 Raw material inlet 38 Raw material supply valve 39 Raw material supply port 40 Product discharge port 41 Product discharge valve 42 Product extraction port 43 Top plate 44 Fine powder discharge portion 45 Fine powder discharge port 46 Cold air inlet 47 First space 48 Second Space 49 Surface modification zone 50 Classification zone 101 Replenishment developer container 102 Developer 103 Cleaning unit 104 Waste developer container 105 Replenishment developer inlet 106 Discharge port E Resistance measurement cell L Sample thickness

Claims (9)

A two-component developer containing a magnetic carrier and a toner,
The magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles,
The two-component developer includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. Used in an image forming apparatus using a photoreceptor provided with a surface protective layer containing at least one selected,
The porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 (g / cm ³ ), where ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm. ³ or less, ρ1 / ρ2 is 0.20 or more and 0.42 or less,
The specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less,
The specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less,
The toner contains toner particles containing at least a binder resin and a release agent, and in the endothermic curve measured by a differential scanning calorimeter (DSC), one or more in a temperature range of 30 ° C. or more and 200 ° C. or less A two-component developer having a plurality of endothermic peaks, wherein a peak temperature of a maximum endothermic peak among the endothermic peaks is 55 ° C or higher and 140 ° C or lower.   The toner contains fine particles having a number average particle diameter of 60 nm or more and 300 nm or less, and the content of the fine particles is 0.5 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The two-component developer according to claim 1, wherein the two-component developer is present.   The two-component developer according to claim 1, wherein the resin component contains at least a silicone resin and a coupling agent.   The toner is a release agent containing at least a copolymer polymerized using one or more (meth) acrylic acid monomers selected from styrene monomers and (meth) acrylic acid monomers, and polyolefin. The two-component developer according to any one of claims 1 to 3, further comprising a mold dispersant. A replenishment developer used in a two-component development method in which a replenishment developer containing at least a toner and a magnetic carrier is replenished to the developing unit, and at least the excess magnetic carrier in the developing unit is discharged from the development unit. And
The replenishment developer contains the toner in a blending ratio of 2 parts by weight or more and 50 parts by weight or less with respect to 1 part by weight of the magnetic carrier.
The magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles,
The two-component developer includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer. Used in an image forming apparatus using a photoreceptor provided with a surface protective layer containing at least one selected,
The porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 (g / cm ³ ), where ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm. ³ or less, ρ1 / ρ2 is 0.20 or more and 0.42 or less,
The specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less,
Specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more, 1.0 × 10 ¹⁷ Ω · cm.
cm or less,
The toner contains toner particles containing at least a binder resin and a release agent, and in the endothermic curve measured by a differential scanning calorimeter (DSC), one or more in a temperature range of 30 ° C. or more and 200 ° C. or less A replenishment developer having a plurality of endothermic peaks, wherein a peak temperature of a maximum endothermic peak among the endothermic peaks is 55 ° C or higher and 140 ° C or lower.   The toner contains fine particles having a number average particle diameter of 60 nm or more and 300 nm or less, and the content of the fine particles is 0.5 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The replenishment developer according to claim 5, wherein the developer is a replenishment developer.   The replenishment developer according to claim 5 or 6, wherein the resin component contains at least a silicone resin and a coupling agent.   The toner is a release agent containing at least a copolymer polymerized using one or more (meth) acrylic acid monomers selected from styrene monomers and (meth) acrylic acid monomers, and polyolefin. The replenishment developer according to any one of claims 5 to 7, further comprising a mold dispersant. A conductive substrate, a photoreceptor having at least a photoconductive layer on the conductive substrate, and a developer carrier that carries a two-component developer containing a magnetic carrier and a toner, are disposed opposite to each other; In the image forming method to be developed,
The photoreceptor further includes a surface protective layer including at least one selected from the group consisting of amorphous silicon, amorphous carbon, and amorphous silicon nitride on the photoconductive layer,
The magnetic carrier is a carrier containing resin-containing magnetic particles containing a resin component in the pores of the porous magnetic core particles,
The porous magnetic core particles have a solid apparent density of ρ1 (g / cm ³ ) and a true density of ρ2 (
in case of a g / cm ^3), ρ1 is 0.80 g / cm ³ or more and 2.40 g / cm ³ or less, .rho.1 / [rho] 2 is 0.20 or more and 0.42 or less,
The specific resistance of the porous magnetic core particles is 1.0 × 10 ³ Ω · cm or more and 5.0 × 10 ⁷ Ω · cm or less,
The specific resistance of the magnetic carrier is 1.0 × 10 ¹⁰ Ω · cm or more and 1.0 × 10 ¹⁷ Ω · cm or less,
The toner contains at least a binder resin and a release agent, and has one or more endothermic peaks in a temperature range of 30 ° C. or higher and 200 ° C. or lower in an endothermic curve measured by a differential scanning calorimeter (DSC). And the peak temperature of the maximum endothermic peak in the endothermic peak is 55 ° C. or higher and 140 ° C. or lower.

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