JP2006038961A - Electrostatic charge image developing carrier, electrostatic charge image developer, method for manufacturing electrostatic charge image developing carrier, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an image having high image quality and to stabilize image formation as against deterioration with lapse of time and an environmental fluctuation. <P>SOLUTION: The electrostatic charge image developing carrier is composed of a core material subjected to a coating treatment by a coating coating resin layer, wherein the core material is ≥1.220 in the sphericity expressed by formula (I): the sphericity=(L/2)2x(π/S) (where L: the maximum diameter of a particle projection image, S: the area of the particle projection image and) is ≥1.8 to ≤6.0 in the surface roughness expressed by formula (II): the surface roughness=SBET/S' (where, SBET: the BET specific surface area of the particles, S': the specific surface area of the equivalent true sphere) and the coating resin layer contains acicular conductive powder and the surface roughness of the carrier obtained by subjecting the core material to the coating treatment by the coating resin layer is ≤1.6 and the developer including such carrier and the image forming method using the developer are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrostatic charge image developing carrier, an electrostatic latent image developer, and an image forming method used when developing an electrostatic latent image formed by electrophotography, electrostatic recording method or the like.

  A method for visualizing image information through an electrostatic latent image, such as electrophotography, is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoconductor in a charging and exposure process, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer used alone such as a magnetic toner. The two-component developer is a carrier agitated by a developer, Since functions such as transport and charging are shared and functions are separated as a developer, they are widely used for reasons such as good controllability.

  As a developing method, a cascade method has been used in the past, but at present, a magnetic brush method using a magnetic roll as a developer transport carrier is mainly used. As the two-component magnetic brush development, conductive magnetic brush (CMB) development using a conductive carrier and insulating magnetic brush (IMB) development using an insulating carrier are known. Among them, in CMB development, since the electric resistance of the carrier is low, charges are injected from the developing roll, and the carrier in the vicinity of the photoconductor acts as a developing electrode to increase the effective developing electric field. It is characterized by being sufficiently performed and having excellent solid image reproducibility. As a conductive carrier, an iron powder carrier has been known for a long time.

  However, many disadvantages have been observed with iron powder carriers. For example, since the saturation magnetization is large, the magnetic brush is too hard to easily damage the photoconductor, and because the specific gravity is large, the impact force applied to the toner during stirring in the developing device is too large and the toner is likely to deteriorate. There is. In order to improve such problems, recently, a carrier has been proposed in which a ferrite or magnetite is used as a carrier core material and a coating resin layer containing conductive powder is formed on the core material (for example, a patent Document 1, Patent Document 2, etc.). As the coating resin, styrene acrylic resin, silicone resin, polyolefin resin, polyester resin, fluorine resin, or the like is used. Carbon black, graphite, zinc oxide, titanium black, iron oxide, titanium oxide, tin oxide, etc. are used as the conductive powder.

  Further, there is a problem that the carrier provided with the coating resin layer has to be improved.

  One is that the coating resin layer is worn or peeled off due to contact with the toner or contact between the carriers during long-term use, and the charging property is lowered. In addition, many conductive powders have hydroxyl groups on the surface, and the surface is often porous, which makes it easier to adsorb water. It is a problem that fluctuates.

  In order to ensure stability against the environmental fluctuations described above, it is effective to blend acicular conductive powder. In addition, it is effective to blend spherical conductive powder with respect to stability against deterioration over time. It has already been proposed to improve the stability against environmental fluctuations and deterioration over time by mixing acicular conductive powder and spherical conductive powder at a predetermined ratio (for example, Patent Document 3).

  However, by simply covering the carrier core material with a conductive resin layer, it is possible to prevent carrier adhesion due to charge injection into the brush mark or the photoconductor, but development of the edge of the electrostatic latent image on the photoconductor In some cases, the image may be lost due to a defect.

  Accordingly, in recent years, there has been a growing demand for higher quality image quality, and in particular, in color image formation, a tendency to reduce the diameter of toner is remarkable in order to realize high-definition images. Even if the particle size distribution of the conventional toner is simply reduced, the presence of the toner on the fine powder side in the particle size distribution causes the problem of carrier and photoconductor contamination and toner scattering, resulting in high quality image quality and high image quality. It is difficult to achieve reliability at the same time. In order to simultaneously achieve high quality image quality and high reliability, it is necessary to sharpen the toner particle size distribution and reduce the particle size. In response to this requirement, as shown in Patent Document 4 and the like, a toner by an emulsion polymerization aggregation method has been proposed. A highly reliable toner for developing an electrostatic charge image having excellent characteristics such as color developability, chargeability, developability, transferability, fixability, particularly chargeability and color developability can be obtained. Depending on the combination, sufficient performance may not be achieved. For example, by coating the surface of the carrier core material with a copolymer of a nitrogen-containing fluorinated alkyl (meth) acrylate and a vinyl monomer, or a copolymer of a fluorinated alkyl (meth) acrylate and a nitrogen-containing vinyl monomer. It has been proposed to obtain a relatively long-life film carrier (see, for example, Patent Document 5, Patent Document 6, and Patent Document 7).

  Patent Document 8 proposes that a polyamide resin is coated on the surface of a carrier core material, and Patent Document 9 is coated with a melamine resin and further cured to obtain a coated carrier having a relatively hard film. However, these carriers can prevent the coating component from peeling off, and can prevent spent toner components from adhering to the carrier surface and contaminating, but the combination with the aggregating toner described above increases the chargeability. It is not satisfactory because it causes a decrease in image density or the carrier is developed together with the toner and white spots are generated. In particular, it is necessary to develop a carrier suitable for this aggregation toner.

  The above-disclosed past solutions have long lifespan, but have not yet been found to have a sufficient effect, particularly in terms of preventing image defects in high-quality color image requirements.

Japanese Unexamined Patent Publication No. 1-7255 JP-A-4-360156 Japanese Patent Application No.10-5421 JP-A-10-198070 JP 61-80161 A JP 61-80162 A JP 61-80163 A JP-A-1-118150 Japanese Patent Laid-Open No. 2-79862

  Therefore, the present invention solves the above problems, can form a good high-quality color image for an image obtained by the electrostatic latent image developing method, and has high stability against environmental fluctuations and deterioration over time. An electrostatic charge image developing carrier, an electrostatic charge image developer, and an image forming method are provided.

  As a result of researches on the above problems, the present inventors have used a toner having a specific shape and a carrier core material having a specific surface property, and the carrier shape and development after containing a specific conductive powder. It has been found that a high-quality color image can be obtained while further improving the stability against deterioration with time and environmental fluctuation by keeping the resistance value range of the agent within a specific range.

  That is, the configuration of the present invention is as follows.

  (1) A carrier in which a core material is coated with a coating resin layer, and the core material has a sphericity represented by formula (I) of 1.220 or less and a surface roughness represented by formula (II) Is 1.8 or more and 6.0 or less, the coating resin layer contains acicular conductive powder, and the surface roughness of the carrier obtained by coating the core material with the coating resin layer is 1.6 or less. The electrostatic charge image developing carrier.

[Formula 1]
Sphericality = (L / 2) ² · π / S (I)
In formula (I), L: maximum diameter of the particle projection image, S: area of the particle projection image.

[Formula 2]
Surface roughness = SBET / S ′ (II)
In formula (II), SBET: BET specific surface area of particles, S ′: true spherical equivalent surface area.

  (2) In the electrostatic charge image developing carrier described in (1) above, a plurality of protrusions are formed on the surface of the core of the carrier, and vertices of the plurality of protrusions formed on the core are connected. The difference between the radius of the virtual outer sphere formed by connecting the base of the plurality of protrusions formed on the core member and the radius of the virtual inner sphere formed by connecting the plurality of protrusions formed on the core member is 0.5 to 5 μm. It is a carrier for developing a charge image.

  (3) An electrostatic charge image developer containing a toner and a carrier, wherein the carrier is the electrostatic charge image developing carrier according to claim 1 or 2.

  (4) In the electrostatic charge image developer according to (3), the toner is produced by an aggregation method and has a shape factor SF1 of 135 or less, and is produced by mixing with the carrier. It is an agent.

(5) In the electrostatic charge image developer according to (3), the toner is a toner for developing an electrostatic charge image including at least resin particles and colorant particles, wherein the resin particles are dispersed. A first step of forming aggregated particles by heating to a temperature below the glass transition point of the resin particles in the liquid to prepare an aggregated particle dispersion; and fine particles dispersed in the aggregated particle dispersion A static process produced by a production method comprising a second step of adding and mixing a fine particle dispersion to adhere the fine particles to the aggregated particles to form adhered particles, and a third step of heating and fusing the adhered particles. It is a toner for developing a charge image, and is a toner for developing an electrostatic image satisfying the following two conditions (i) and (ii), in which the dispersion state of the colorant particles inside the toner measured by a transmission electron microscope. .
(I) The number dispersion average particle diameter of the colorant particles is in the range of 40 to 60 nm.
(Ii) 70% by number or more of particles having a number dispersion average particle diameter in the range of 40 to 60 nm and 10% by weight or less of coarse side particles having a number dispersion average particle diameter of 200 nm or more in the entire colorant particles.

(6) In the carrier for developing an electrostatic charge image according to any one of (3) to (5), the electric resistance when the measured electric field of the electrostatic charge image developer is 1 × 10 ⁴ V / cm is 1. A developer for developing an electrostatic image having x10 ⁵ to 1 × 10 ⁸ Ω · cm and a chargeability in the range of 15 to 25 μc / g.

  (7) A dispersion average obtained by mixing magnetic materials in advance and calcining at a high temperature, then pulverizing them to particles having a particle diameter of 0.5 μm or less, adding a dispersant and a binder to the particles, granulating the particles, and treating the particles at a high temperature A substantially spherical magnetic particle having a particle size of 0.5 to 5 μm and a substantially spherical magnetic particle having a dispersion average particle size of 5 to 100 μm are prepared, and a dispersant and a binder are added to the magnetic particles having two different particle sizes. , Granulated at high temperature, classified, and magnetic core material having a volume average particle diameter of 10 to 50 μm having protrusions of substantially hemispherical magnetic particles of 0.5 to 5 μm on the surface of the magnetic core material Is a method for producing a carrier for developing an electrostatic charge image using as a carrier core material.

  (8) a step of forming a latent image on the latent image carrier, a step of developing the latent image using a developer, a step of transferring the developed toner image to a transfer member, and a toner image on the transfer member An image forming method using the electrostatic latent image developer described in any one of (3) to (6) above as the developer.

  According to the present invention, it is possible to form a good halftone image on an image obtained by an electrostatic latent image developing method, particularly a high-quality color image, and to be stable against environmental fluctuations and deterioration over time. Can provide a high developer and an image forming method.

  Hereinafter, the present invention will be described with reference to preferred embodiments.

[Career]
As the material of the carrier core material used in the present invention, any conventionally known material can be used, and ferrite or magnetite is particularly preferably selected. For example, iron powder is known as another carrier core material. In the case of iron powder, since the specific gravity is large and the toner is likely to be deteriorated, ferrite and magnetite are more stable. An example of ferrite is generally represented by the following formula.

(MO) _X (Fe ₂ O ₃ ) _Y
(In the formula, M contains at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo and the like: X, Y represents the molar ratio by weight and satisfies the condition X + Y = 100)

  The M is preferably a ferrite particle which is one or a combination of Li, Mg, Ca, Mn, Sr and Sn, and the content of other components is 1% by weight or less. By adding Cu, Zn, and Ni elements, the resistance tends to be low and charge leakage is likely to occur. In addition, the resin tends to be difficult to coat, and the environmental dependency tends to deteriorate. Furthermore, since it is a heavy metal, the stress given to a carrier becomes strong because it is heavy, and it may have a bad influence on life property. From the viewpoint of safety, in recent years, those to which Mn or Mg element is added have become widespread.

  As an example of a method for producing a ferrite core material, an appropriate amount of each oxide is first blended, pulverized, mixed and dried for 10 hours by a wet ball mill, and then held at 950 ° C. for 4 hours. This is pulverized with a wet ball mill for 24 hours to 1 μm or less. This slurry can be granulated and dried, and maintained at 1100-1300 ° C. for 6 hours while controlling the oxygen concentration for the purpose of adjusting magnetic properties and resistance, and then pulverized and further classified into a desired particle size distribution. it can.

  The carrier core material used in the present invention has a sphericity of 1.220 or less and a surface roughness of 1.8 or more and 6 or less, preferably a sphericity of 1.2 or less and a surface roughness of 2 or more. The range is 5 or less. The closer the sphericity is to 1, the closer the shape is to a true sphere, and the greater the surface roughness, the finer irregularities exist on the surface. In the present invention, by adjusting the sphericity of the core material to be equal to or less than 1.220 and making it close to a true sphere, the carrier fluidity is improved and the uniform resin layer can be coated, and the aggregation of the core material particles is suppressed. Therefore, the production yield can be improved. In addition, by adjusting the surface roughness of the core material to 1.8 or more and making the surface have fine irregularities, the coating resin layer can be firmly fixed by the anchor effect, thus preventing the coating layer from peeling off from the carrier. it can. On the other hand, by making the surface roughness of the core material 6 or less, there is an advantage that it is easy to prevent and control a decrease in electrical resistance due to contact between the convex portions on the carrier surface. Further, by forming a uniform resin layer coating, the carrier surface roughness can be kept to 1.6 or less, preferably 1.3 or less, so that a flatter coating resin layer can be formed and the impact force of the carrier on the toner can be reduced. be able to. As a result, it is possible to prevent so-called toner spent in which the toner composition is fused to the carrier surface.

  Here, the sphericity of the carrier core material can be obtained from the above formula by measuring the maximum diameter and the projected area of the projected image of the core particle using, for example, an image analysis device (Mitani Corporation). Further, the BET specific surface area of the carrier core material can be determined by a normal nitrogen adsorption method. The true spherical equivalent specific surface area of the carrier core material can be calculated from the average particle diameter and true specific gravity. Similarly, the true spherical equivalent specific surface area of the carrier can be calculated from the average particle diameter and true specific gravity. The surface roughness of the carrier is determined by measuring the BET specific surface area of the carrier.

  Further, as shown in FIG. 1, the surface of the carrier core material 10 is formed by forming a plurality of protrusions 20 and connecting the vertices of the plurality of protrusions 20 formed on the core material 10 as shown in FIG. The difference between the radius of the virtual outer sphere 14 and the radius of the virtual inner sphere 12 formed by connecting the base portions of the plurality of protrusions 20 formed on the core member 10 (difference indicated by the double arrow 22) Is 0.5 to 5 μm. In order to form such a core material 10, magnetic materials are mixed in advance and calcined at a high temperature, and then pulverized to obtain particles having a dispersion average particle size of 0.5 μm or less, preferably 0.1 μm or less. . A substantially spherical magnetic substance particle having a dispersion average particle diameter of 0.5 to 5 μm and a substantially spherical magnetic substance particle having a dispersion average particle diameter of 5 to 100 μm, which are granulated by appropriately adding a dispersant and a binder to the particles and processed at high temperature, In order to adjust the magnetic properties and resistance, the magnetic particles having two different particle sizes are granulated by adding a dispersant and a binder as appropriate, and subjected to high temperature treatment while controlling the oxygen concentration, and classified. Thus, a 10-50 μm magnetic core material having the above-described protrusions of substantially hemispherical magnetic particles of 0.5-5 μm on the surface of the magnetic core material can be obtained as a carrier core material. The measurement of the virtual inner sphere and the virtual outer sphere is performed using a scanning electron microscope S4100 (manufactured by Hitachi, Ltd.).

  The method for controlling the exposed area on the surface of the core material can be controlled by the combination and blending ratio of the oxides. It can also be controlled by the firing temperature, holding time, and oxygen concentration.

  Since the surface of the carrier core material used in the present invention has fine irregularities, the coating resin layer can be firmly fixed by the anchor effect, and therefore the peeling of the coating layer from the carrier can be prevented. Further, when the toner concentration is increased by making the surface of the carrier core material have a protruding portion of 0.5 to 5 μm, an electric path is formed at the protruding portion, and the resistance value of the developer depends on the toner concentration. This is because it becomes difficult.

The magnetic susceptibility σ of the carrier core material of the present invention is measured by the BH tracer method using a VSM (vibration sample method) measuring device in a magnetic field of 1 kOe, and the magnetization value σ1000 is 60 to 90 Am ² / kg (emu / g), preferably in the range of 70 to 85 Am ² / kg (emu / g). When σ1000 is less than 60 Am ² / kg (emu / g), the magnetic attraction force to the developing roll becomes weak and adheres to the photoconductor to cause image defects, which is not preferable. On the other hand, when σ1000 exceeds 90 Am ² / kg (emu / g), the magnetic brush becomes too hard, and the photoreceptor is easily rubbed and easily damaged.

  The average particle size of the carrier core material of the present invention is 10 to 100 μm, preferably 20 to 50 μm. If the average particle size is smaller than 10 μm, the developer tends to scatter from the developing device, and if it is larger than 100 μm, it is difficult to obtain a sufficient image density.

  The conductive powder of the present invention can be used in various shapes such as needles and spheres, but needle-shaped conductive powders are more suitable for improving environmental stability. In order to ensure the stability over time, spherical conductive powder is suitable. The term “needle” as used herein refers to those having a major axis / minor axis ratio (major axis / minor axis: hereinafter referred to as “aspect ratio”) of 3 or more, preferably 5 or more, more preferably 10 or more.

  The acicular conductive powder preferably has a major axis of 0.05 to 20 μm. Even if the aspect ratio is 3 or more, if the major axis is shorter than 0.05 μm, the conductive powder is destroyed in the process of dispersing in the coating resin, and the effect of the acicular conductive powder is reduced. On the other hand, when the long axis is longer than 20 μm, the conductive powder is easily detached from the coating resin layer. Among them, the short axis of the acicular conductive powder is preferably 0.01 to 1 μm. Outside this range, the dispersibility may decrease and the carrier characteristics may become non-uniform.

  The spherical conductive powder preferably has an average particle size of 0.01 to 1 μm. Outside this range, the dispersibility is deteriorated and the conductive powder is easily detached from the coating resin layer, which is not preferable. The content of the conductive powder in the coating resin layer is 25 to 45% by volume, preferably 30 to 40% by volume. When hard conductive powder is contained in the coating resin layer, the coating resin layer becomes hard due to the reinforcing effect of the conductive powder, and the external additives such as silica, titania and alumina adhering to the toner are impacted into the coating resin layer. Is prevented and durability is improved. If the content of the conductive powder is less than 25% by volume, the reinforcing effect is not sufficiently exerted, and if it is more than 45% by volume, the conductive powder tends to be detached, which is not preferable.

In addition, the mechanism has not been fully elucidated, but among the conductive powders in the coating resin layer, acicular conductive powder is contained in a volume mixing ratio of 20% or more, preferably 50% or more, more preferably 75% or more. By making it, environmental stability can be improved more. If the volume mixing ratio of the acicular conductive powder is less than 20%, the effect is not sufficiently exhibited. In the present invention, as long as the sphericity and surface roughness of the carrier core material are within a predetermined range, a predetermined effect can be obtained without blending the spherical conductive powder. The electric resistance of the conductive powder is preferably 1 × 10 ⁶ Ω · cm or less. When this value is exceeded, it becomes difficult to obtain a desired electrical resistance as a whole carrier.

  The material of the conductive powder of the present invention is not particularly limited as long as it has a desired shape and electrical resistance. For example, the surface of fine particles of titanium oxide, zinc oxide, aluminum borate, potassium titanate, tin oxide, etc. A composite system in which is coated with a conductive metal oxide or a conductive metal oxide simple substance system is preferable. Here, examples of the conductive metal oxide include metal oxide doped with antimony or the like (for example, antimony-doped tin oxide), oxygen-deficient metal oxide (for example, oxygen-deficient tin oxide), or the like.

The electric resistance of the carrier on which the coating resin layer is formed is in the range of 1 × 10 to 1 × 10 ⁸ Ω · cm, preferably 1 × 10 ³ to 1 × 10 ⁷ Ω · cm when the measurement electric field is 100 V / cm. Is appropriate.

  The chargeability of the carrier on which the coating resin layer is formed is preferably 15 to 25 μC / g. When the chargeability of the carrier is less than 15 μC / g, there is a high possibility that the toner stain on the day image portion (fogging will occur) and a high-quality color image cannot be obtained, while the chargeability of the carrier is 25 μC. When it exceeds / g, it becomes difficult to obtain a sufficient image density.

  The electrical resistance of the coating resin layer can be controlled by the type and amount of conductive powder and coating resin used.

Then, if the electric resistance of the carrier on which the coating resin layer is formed is smaller than 1 × 10 Ω · cm, the charge easily moves on the surface of the carrier, and image defects such as brush marks are likely to occur, and the printing operation is not performed for a while. If left unattended, the chargeability becomes too low, and background stains occur on the first print. If the electric resistance of the carrier on which the coating resin layer is formed is greater than 1 × 10 ⁸ Ω · cm, not only a good solid image can be obtained, but if the continuous printing is repeated many times, the toner charge becomes too large and the image density becomes too high. It will go down.

The electric resistance of the coating resin layer is 10 ² V / cm by forming a coating resin film having a thickness of about several μm on an ITO conductive glass substrate using an applicator or the like, and forming a gold electrode thereon by vapor deposition. Obtained from current-voltage characteristics in an electric field.

The electrokinetic resistance when measured in the form of a carrier magnetic brush is 1 × 10 to 1 × 10 ⁸ Ω · cm, preferably 1 × 10 ³ to 1 × 10 ⁷ Ω, under an electric field of 10 ⁴ V / cm. A range of cm is appropriate. If the dynamic electrical resistance is less than 1 × 10 Ω · cm, image defects such as brush marks are likely to occur, and if it is greater than 1 × 10 ⁸ Ω · cm, it is difficult to obtain a good solid image. The electric field of 10 ⁴ V / cm is close to the developing electric field in an actual machine, and the dynamic electric resistance is a value under this electric field.

From the above, the electrokinetic resistance when the carrier and the toner are mixed is suitably in the range of 1 × 10 ⁵ to 1 × 10 ⁸ Ω · cm under an electric field of 10 ⁴ V / cm. On the other hand, if it is less than 1 × 10 ⁵ Ω · cm, the resolution deteriorates due to background stains due to a decrease in toner chargeability after standing after printing, and thickening of line images due to over-development. If it exceeds 1 × 10 ⁸ Ω · cm, problems such as the inability to obtain a high-quality image due to a decrease in developability at the edge of the solid image occur.

The dynamic electrical resistance of the carrier is obtained as follows. A magnetic brush is formed by placing a carrier of about 30 cm ³ on the developing roll (the magnetic field of the sleeve surface of the developing roll is 1 kOe), and a plate electrode having an area of 3 cm ² is placed on the developing roll at intervals of 2.5 mm. Make them face each other. A voltage is applied between the developing roll and the plate electrode while rotating the developing roll at a rotation speed of 120 rpm, and the current flowing at that time is measured. The dynamic electric resistance is obtained from the obtained current-voltage characteristics using Ohm's law equation. It is well known that there is generally a relationship of ln (I / V) ∝V × 1/2 between the applied voltage V and the current I at this time. When the dynamic electrical resistance is quite low as in the carrier used in the present invention, measurement may not be possible because a large current flows in a high electric field of 10 ³ V / cm or more. In such a case, three or more points are measured in a low electric field, and an electric field of 10 ⁴ V / cm is extrapolated by the least square method using the above relational expression.

  Examples of the coating resin formed on the carrier core material include polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, Polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bond or modified product thereof; fluororesin such as polytetrafluoroethylene, polyfluoride Vinyl, polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate, amino resin such as urea-formal Hydrin resins; epoxy resins. These may be used alone or in combination with a plurality of resins.

  The thickness of the coating resin layer is 0.3 to 5 μm, preferably 0.5 to 3 μm. If the thickness of the coating resin layer is smaller than 0.3 μm, it is difficult to form a uniform and flat coating resin layer on the surface of the carrier core material. On the other hand, if it is larger than 5 μm, carriers are aggregated and it is difficult to obtain a uniform carrier.

  The method of forming the coating resin layer on the carrier core material includes an immersion method in which the carrier core material is immersed in the coating resin layer forming solution, a spray method in which the coating resin layer forming solution is sprayed on the surface of the carrier core material, and a carrier core. Examples include a fluidized bed method in which a coating resin layer forming solution is sprayed in a state where the material is suspended by flowing air, a kneader coater method in which a carrier core material and a coating resin layer forming solution are mixed in a kneader coater and the solvent is removed. It is done.

  The solvent used in the coating resin layer forming solution is not particularly limited as long as it dissolves the coating resin, and examples thereof include aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used. Examples of the method for dispersing the conductive powder include a sand mill, a dyno mill, and a homomixer.

[Developer]
Here, the developer used is a two-component developer composed of a toner and a carrier. However, the toner described below may be a magnetic toner or a non-magnetic toner, or may be a one-component developer using this toner alone.

  The toner used in the present invention is a dispersion in which at least resin particles are dispersed and heated to a temperature not higher than the glass transition point of the resin particles to form aggregated particles, thereby preparing an aggregated particle dispersion. A first step, a second step of adding and mixing a fine particle dispersion in which fine particles are dispersed in the aggregated particle dispersion to form the adhered particles by adhering the fine particles to the aggregated particles; and The toner is produced by a so-called agglomeration and coalescence method including a third step of fusing by heating.

  The characteristics of this toner are that the particle shape is relatively round and the particle size distribution is narrow, the toner surface is relatively uniform, the charging property is high, and the charge distribution is narrow and good.

  Therefore, since the developer for developing an electrostatic charge image obtained by mixing with the carrier has a very high fluidity and good developability, a good product can be obtained as a high-quality color developer.

  As other toners, polymerized toners, dissolved suspension toners, kneading / pulverizing / classifying / spheroidizing toners and the like can be used, but a sufficient developer cannot be obtained.

  Thus, with the polymerized toner, it is easy to obtain a narrow particle size distribution / spherical toner, but impurities such as a dispersant remain on the toner surface and good chargeability cannot be obtained. In addition, a spherical toner can be easily obtained with a dissolved suspension toner, but classification is necessary because it has a wide particle size distribution and particularly easily contains a fine powder toner. In some cases, fine powder that cannot be removed by classification is included, which accumulates on the carrier surface and increases the carrier resistance relatively quickly, and the resistance value increases at a low toner concentration, so a uniform image can be obtained in the short term. There are obstacles such as being impossible.

  Furthermore, the toner obtained by the manufacturing method such as kneading / pulverization / classification / spheroidizing toner has a low yield, and the toner surface is modified at the time of spheronization, so that the fluidity, charging property, etc. are deteriorated. There are problems such as difficult to obtain.

  Therefore, in the present invention, a dissolved suspension toner is used as the toner.

  In this embodiment, as each color component toner, styrene acrylic resin fine particles and yellow, magenta, cyan and black pigment fine particles are agglomerated and united to form a volume average particle size of about 3 to 7 μm and a shape factor SF1. A toner having an average value in the range of 100 to 135 and a shape factor of 115 or less in the shape factor distribution is used. The shape factor SF1 can be obtained by the following equation.

SF1 = (ML ² / A) × (π / 4) × 100
Here, ML is an average value of absolute maximum lengths of particles, A is a projected area of particles, and these are quantified mainly by analyzing a microscope image or an operation electron microscope image with an image analyzer.

The method for obtaining the shape factor distribution is as follows. Disperse the toner on a slide glass, capture the optical microscope image into a Luzex image analyzer through a video camera, calculate the square of the maximum length of 100 toners / projection area (ML ² / A), and calculate the larger one From the above, the shape which becomes 16% cumulative and the shape which becomes 84% are measured. The shape factor distribution is obtained by dividing the shape of 84% by the shape of 16% and raising it to the power of 0.5.

  For example, as disclosed in JP-A-10-026842, JP-A-10-133423, JP-A-10-198070, JP-A-11-231570, etc., this toner has at least resin particles dispersed therein. A first step of forming aggregated particles by heating to a temperature below the glass transition point of the resin particles to prepare an aggregated particle dispersion, and dispersing the fine particles in the aggregated particle dispersion A second step of adding and mixing the resulting fine particle dispersion to adhere the fine particles to the agglomerated particles to form the adhered particles, and a third step of heating and fusing the adhered particles. The toner is produced by a method for producing a toner for developing an electrostatic image.

  Adjustment of the volume average particle diameter, shape, and distribution can be adjusted by adjusting the aggregated particle dispersion, the conditions for forming the adhered particles, and the conditions for heating and fusing the adhered particles.

  The dispersion is obtained by dispersing at least resin particles. The resin particles are resin particles. Examples of the resin include thermoplastic binder resins. Specifically, homopolymers or copolymers (styrene-based resins) of styrenes such as styrene, parachlorostyrene, and α-methylstyrene; acrylic Methyl acid, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, methacrylic acid 2 -Homopolymers or copolymers of vinyl group esters such as ethylhexyl (vinyl resins); Homopolymers or copolymers of vinyl nitriles such as acrylonitrile and methacrylonitrile (vinyl resins); A single vinyl ether such as ether or vinyl isobutyl ether Polymer or copolymer (vinyl resin); homopolymer or copolymer of vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone (vinyl resin); ethylene, propylene, butadiene, isoprene, etc. Homopolymers or copolymers of olefins (olefin resins); non-vinyl condensation resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, and polyether resins, and these non-vinyl condensation resins And a graft polymer of a vinyl monomer and the like. These resins may be used alone or in combination of two or more.

  Among these resins, styrene resins, vinyl resins, polyester resins, and olefin resins are preferable. Copolymers of styrene and n-butyl acrylate, n-butyl acrylate, bisphenol A / fumaric acid copolymer. Particularly preferred is a copolymer of styrene and olefin.

  As an average particle diameter of the said resin particle, it is 1 micrometer or less normally, and it is preferable that it is 0.01-1 micrometer. When the average particle size exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the average particle size is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toners is improved, and the variation in performance and reliability is advantageous. The average particle diameter in the previous period can be measured, for example, using a laser diffraction method (Horiba, Ltd .: LA-700).

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, and brilliant. Carmine 6B, Daypon Oil Red, Pyrazolone Red, Risor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalley Various pigments such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, dioxadi System, thiazine, azomethine, indigo, thioindigo, phthalocyanine, aniline black, polymethine, triphenylmethane dyes, diphenylmethane dyes, thiazine, thiazole type, various dyes such as xanthene; and the like. These colorants may be used alone or in combination of two or more.

  The volume average particle size of the colorant is usually 1 μm or less, preferably 0.01 to 1 μm. When the volume average particle size exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the volume average particle size is within the above range, there are no disadvantages, and it is advantageous in that uneven distribution among toners is reduced, dispersion in the toner is improved, and variations in performance and reliability are reduced. . The average particle diameter can be measured using, for example, a laser diffraction method (manufactured by Horiba: LA-700).

  In the present invention, other components such as a release agent, an internal additive, a charge control agent, an inorganic particle, a lubricant, and an abrasive may be dispersed in the dispersion according to the purpose. In this case, other particles may be dispersed in a dispersion obtained by dispersing resin particles, or a dispersion obtained by dispersing other particles is mixed in a dispersion obtained by dispersing resin particles. May be.

  Examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide. Plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax -Petroleum wax; and modified products thereof.

  These waxes are dispersed in water together with a polymer electrolyte such as an ionic surfactant, polymer acid, polymer base, etc., heated above the melting point, and can be applied with a strong shearing force or pressure discharge type. When processed using a disperser, it can be easily made into fine particles of 1 μm or less.

  Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments. In addition, as the charge control agent in the present invention, a material that is difficult to dissolve in water is preferable in terms of controlling ionic strength that affects stability during aggregation and fusion and reducing wastewater contamination.

  Examples of the inorganic particles include all particles usually used as external additives on the toner surface, such as silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, and cerium oxide. Examples of the lubricant include fatty acid amides such as ethylene bisstearamide and oleic acid amide, and fatty acid metal salts such as zinc stearate and calcium stearate. Examples of the abrasive include the aforementioned silica, alumina, cerium oxide, and the like.

  The toner has a volume average particle size of 10 μm or less, preferably 3 to 7 μm.

  The ratio of the toner in producing the developer by mixing the toner and the carrier is suitably in the range of 0.3 to 10% by weight, preferably 0.3 to 3% by weight of the whole developer.

If the toner ratio is less than 0.3% by weight, it is difficult to obtain a sufficient image density, and a solid image is difficult to be uniform. On the other hand, if the amount exceeds 10% by weight, the toner coverage on the carrier surface exceeds 100% and the charge amount decreases (when the absolute value of the average charge amount is less than 15 μC / g). Cover) High-quality color images cannot be obtained. For example, if the amount exceeds 3% by weight, the toner coverage on the carrier surface approaches 100%, so that the resistance value as a developer is extremely increased, and is in the range of 1 × 10 ⁵ to 1 × 10 ⁸ Ω · cm. Therefore, a good and high-quality color image such as a blur at the image edge portion cannot be obtained.

  However, in a low-humidity environment, if the toner ratio is less than 3% by weight, a high charge amount (the absolute value of the average charge amount exceeds 25 μC / g) is likely to occur, and it may be difficult to obtain a sufficient image density. Therefore, it is preferable to select the toner ratio so that the absolute value of the charging property is in the range of 15 to 25 μC / g depending on the environment.

  In particular, color images have become widespread and demands for higher image quality have increased. In this color image, the colorant in the toner of each color greatly affects the image quality. The color gamut is greatly affected by the colorants (Y, M, C) added to the toner. Particularly used pigments include good transparency and strong coloring power. The toner was created while observing these characteristics.

  Conventionally, it has been difficult to satisfy these elements, particularly in the case of yellow pigments, and various studies have been made. In order to have good transparency in a yellow toner containing a yellow pigment, it is important that the crystal diameter of the yellow pigment itself is small and that the average particle diameter of the colorant in the toner is small. Originally, the yellow pigment itself is aggregated or aggregated in the toner, such as when the average particle diameter of the colorant is large, or there are many coarse particles of the colorant. Becomes worse. In addition, various problems such as the liberation of the colorant from the toner resin and the deterioration of the chargeability due to the exposure of the colorant to the toner surface occur. In particular, when the average particle diameter of the colorant is too small depending on the type of the yellow pigment, there are cases in which problems such as insufficient colorability of the obtained toner may occur.

  Therefore, in order to solve this problem, JP 2000-228653 A discloses condensed azo yellow pigments, specifically C.I. I. Pig. Yellow 74, 93, 94, 95, 12, 13, 14, 16, 17, 180, etc. are mentioned, but it is not always sufficient.

  Yellow74 can make fine pigment particles relatively easily, but if the average system of pigment particles is 100 nanometers or less, it contains a large proportion of particles of 40 nanometers or less. There is a problem that the color gamut obtained in the initial period in the short term changes greatly and the color gamut becomes narrow. In addition, the same tendency was observed in Yellow 17, and there was a problem that the chargeability deteriorated due to bleeding of the pigment at low pH in the toner preparation process.

  Therefore, compatibility of so-called toner manufacturability is important particularly in selecting a yellow pigment.

  In particular, the Yellow toner is an electrostatic charge image developing toner containing at least resin particles and colorant particles, and the dispersion state of the colorant particles inside the toner measured by a transmission electron microscope has the following two conditions: It is essential to satisfy.

  (1) The dispersion average particle diameter of the colorant particles is in the range of 40 to 60 nm.

  Here, the dispersion average particle diameter of the colorant particles must be in the range of 40 to 60 nm. When the dispersion average particle diameter of the colorant particles exceeds 60 nm, the transparency of the toner for developing an electrostatic image is deteriorated, the color reproduction range is lowered, and the image in OHP becomes dark. In addition, since the incorporation of the pigment into the toner becomes poor, the chargeability of the toner itself tends to deteriorate. On the other hand, when the dispersion average particle diameter of the colorant particles is 40 nm or less, the transparency is high, but the coloring power is lowered due to the deterioration of the pigment when left for a long period of time, and the concealability is lowered. It cannot be used as a toner for developing an electrostatic image.

  (2) 70% by number or more of particles in the range of 40 to 60 nm in the whole colorant particles and 10% by number or less of coarse side particles of 200 nm or more.

  Here, the content of coarse side particles of 200 nm or more in the whole colorant particles is essential to be 10% by number or less, and preferably 5% by number or less.

  When the number of particles in the range of 40 to 60 nm in the whole colorant particles is less than 70% by number, the sharpness is impaired. On the other hand, when the content of the coarse side particles exceeds 10% by number, problems such as a decrease in transparency and a decrease in charging characteristics under high humidity occur. On the other hand, when the content of the coarse side particles is 10% by number or less, there is no such problem, and stable image characteristics can be maintained over a long period of time.

  The conditions of the dispersion state of the two colorant particles (1) and (2) above are measured by a transmission electron microscope (TEM), and specifically, a toner cross-sectional image obtained by a transmission electron microscope. Is applied to the image analysis apparatus. In the present invention, for example, 1000 particles of toner to be measured are arbitrarily sampled, and the number average dispersion average particle diameter and the number average content of coarse side particles of 200 nm or more are obtained for each toner particle. This was measured by averaging.

  Further, in the present invention, the color gamut can be broadened by setting the index value of the pigment concentration represented by the average particle diameter of toner (μm) × the concentration of colorant particles in the toner (wt%) in the range of 10-25. High-quality images can be obtained. This is because if the colorant particle concentration in the toner is increased so that the index value of the pigment concentration exceeds 25, the pigment particles in the toner are easily taken up in an aggregated state. For this reason, problems such as a decrease in transparency and a decrease in the color gamut and an increase in the number of pigments on the toner surface, resulting in a decrease in charging characteristics under high humidity, are caused. On the other hand, if the colorant particle concentration in the toner is lowered so that the index value of the pigment concentration is less than 10, the hiding power of the toner is lowered and the concentration is lowered, and as a result, the amount of toner on the printing paper is increased. As a result, the unit price per sheet increases, and the burden of the transfer process increases, and it becomes impossible to obtain an image with a good quality. As a result, a high-quality color image cannot be achieved.

  In addition, when at least one of the mixture of toner particles having two or more different pigment concentrations is a pigment-free particle, the color reproduction range becomes wider and a high-quality image can be obtained.

  The reason for this is that, according to the present inventors, the pigment concentration in the toner particles is not necessarily constant, and may be an aggregate of toner particles having different concentrations, and further, a transparent toner without pigment. It was found that the color reproduction range was widened by mixing the particles rather than the homogeneous toner. Although this cannot be explained strictly, it seems to be related to the effect of the fixing paper, so even if the amount of toner placed on the paper is the same, for example, a small amount of toner with increased pigment concentration is placed on the paper. In this case, it was found that the color reproduction range of the fixed image was narrower than when a large amount of toner having a reduced pigment concentration was placed on the paper. In various studies as described above, it is possible to obtain an image density and a color reproduction range by combining an index value of a pigment concentration represented by the average particle diameter of toner (μm) × the concentration of colorant particles in toner (wt%). I found that it was necessary.

  From the above, it is desirable that the toner particle mixture has two or more different pigment concentrations, and the index value of the total pigment concentration of the mixture is in the range of 10-25.

  This is because when the index value of the pigment concentration is less than 10, the density decreases, and when the index value of the pigment concentration exceeds 25, the color reproduction range becomes narrow although it cannot be strictly described. In the case of a mixture of toner particles having two or more different pigment concentrations, if a toner whose index value of the pigment concentration of the darker toner greatly exceeds 25, secondary problems such as a decrease in chargeability are caused as described above. This is not preferable because it occurs. One of them may be a transparent toner. The transparent toner and the colored toner do not necessarily have to be the same binder, but if the melting performance at the time of fixing is different, it is not desirable because offset and fixing failure are likely to occur.

  The toner pigment is C.I. I. Pig. It is desirable that it is Yellow-185. This is particularly important for obtaining the required coloring power and transparency.

  C. above. I. Pig. Yellow-185 is a pigment suitable for the agglomeration method because it has excellent chargeability compared to other Yellow pigments. That is, it is considered that the pigment uptake into the toner is good. Therefore, C.I. I. Pig. If Yellow-185 is adjusted to the above-described limited range of pigment dispersion, the highest high-quality color image having excellent transparency and coloring power can be obtained.

  The above yellow toner is also preferably produced by the above-described aggregation method from the viewpoint that the pigment dispersion state in the toner can be easily adjusted, but is not limited thereto.

  The Yellow toner will be described in detail below. In addition, since it is the same except the colorant used in the toner manufacture mentioned above, the description is abbreviate | omitted.

  Examples of the colorant used in the toner of the present invention include carbon black and perylene black as black pigments, and chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow and the like as yellow pigments.

  The red to magenta pigments include permanent orange GTR, pyrazolone orange, balkan orange, watch young red, permanent red, brilliantamine 3B, brilliantamine 6B, dapon oil red, pyrazolone red, resol red, rhodamine B rake, rake. Red C, Rose Bengal, etc.

  Further, examples of blue to cyan pigments include aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, and phthalocyanine blue.

  Examples of the green pigment include phthalocyanine green and malachite green oxalate. In addition to these various pigments, acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black Various dyes such as polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, and xanthene can be used singly or in combination of two or more. In particular, C.I. I. Pigment Yellow-185 is effective as described above in order to widen the color reproduction range.

  As a method for dispersing these colorants, an arbitrary method, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having media, a sand mill, or a dyno mill can be used. Although not limited at all, a disperser such as an optimizer (manufactured by Sugino Machine Co., Ltd.) is suitable in that a fine pigment can be made uniform as in the present invention and the particle size can be made uniform. It is preferable to select the various conditions of the dispersing machine and the dispersant so as to satisfy the conditions (1) and (2) described above.

  In addition, as a method for examining the dispersion state of the colorant, the number average particle diameter value of the colorant particles is obtained by measuring about 50,000 colorant particles using Microtrac (manufactured by Nikkiso). It was determined by averaging the number particle diameter.

  These colorant fine particles may be added together with other fine particle components in the mixed solvent at once, or may be divided and added in multiple stages.

  These resin fine particle dispersion, colorant dispersion and the like are mixed to prepare a uniform mixed particle dispersion, and then a soluble inorganic metal salt is added and mixed in the dispersion medium to obtain desired aggregated particles. At that time, resin fine particles, colorant, if necessary, the above-mentioned inorganic fine particles may be added at once, or the fine particle components are added stepwise by dividing, and the structure of the aggregated particles is, for example, a core-shell structure, You may provide the structure which inclined the component to the radial direction of particle | grains. In that case, the resin fine particle dispersion, the colorant particle dispersion, the release agent fine particle dispersion and the like are mixed and dispersed, and the aggregated particles are grown until the particle size reaches a certain level. If necessary, additional resin fine particles may be added to the surface of the aggregated particles by adding a resin fine particle dispersion or the like. By covering the surface of the agglomerated particles with the additional resin fine particles, it is possible to prevent the colorant, release agent, etc. from being exposed to the toner surface, which is effective in suppressing charging defects and non-uniform charging due to these exposures. is there.

  In the agglomeration step for forming the agglomerated particles described above, an inorganic metal salt having a valence of 2 or more is used as the aggregating agent. The larger the valence of the inorganic metal, the stronger the agglomeration force, and the more stable the aggregation can be controlled. Therefore, an unagglomerated material is hardly generated and an excellent particle size distribution can be obtained. As the tetravalent or higher inorganic metal salt polymer, polyaluminum chloride, polyaluminum hydroxide and the like can be used.

  After obtaining aggregated particles having a desired particle diameter in this manner, the aggregated particles are fused by heating to a temperature equal to or higher than the glass transition point of the resin, whereby desired toner particles can be obtained. Here, the toner shape can be controlled from an indeterminate shape to a spherical shape by selecting the fusion heating condition. When fused for a long time at a high temperature, the toner shape becomes closer to a true sphere.

[Image forming method]
The image forming method of the present invention uses at least the latent image forming step for forming a latent image on the surface of the electrostatic latent image carrier and the electrostatic image developer layer formed on the surface of the developer carrier. An image forming method comprising: a developing step of developing an electrostatic latent image on the surface of the electrostatic latent image carrier to obtain a toner image; and a transfer step of transferring the toner image on the surface of the electrostatic latent image carrier to the surface of the transfer member The electrostatic charge image developer contains the toner for developing an electrostatic charge image of the present invention described above. Further, a fixing step for fixing the toner image transferred to the surface of the transfer member by heat and / or pressure, a cleaning step for removing the electrostatic charge image developer remaining on the surface of the electrostatic latent image carrier after the transfer, etc. You may have.

  Each of the above steps is a general step per se, and is described in, for example, JP-A-56-40868 and JP-A-49-91231. The image forming method of the present invention can be carried out using an image forming apparatus such as a copier or a facsimile machine known per se.

  In the image forming method of the present invention, an embodiment that further includes a recycling step is preferable. The recycling step is a step of transferring the electrostatic image developing toner collected in the cleaning step to the electrostatic image developer layer. The image forming method including the recycling step can be performed using an image forming apparatus such as a toner recycling system type copying machine or facsimile machine.

  The present invention can also be applied to a recycling system in which the cleaning process is omitted and toner is collected simultaneously with development.

  In the toner of the present invention, the specific molecular weight distribution is obtained under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)” apparatus, and column uses “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)”. THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

  In the present invention, the particle size distribution was measured using a Coulter Counter TA-II type (manufactured by Beckman Coulter), and ISOTON-II (manufactured by Beckman Coulter) was used as the electrolyte.

  As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant. After adding this to 100 ml of the electrolytic solution, the electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and with the Coulter counter TA-II type, an aperture diameter of 2 is used with a 100 μm aperture. The particle size distribution of ˜60 μm particles was measured to determine the volume average particle size. The number of particles measured was 50,000.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
[Manufacture of carrier A]
100 parts by weight of ferrite (manufactured by Dowa Iron Powder Industry Co., Ltd., DFC450-320, volume average particle size 35 μm, sphericity 1.196, surface roughness 4.15, magnetization value 73 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (antimony-doped tin oxide coating) Titanium oxide) 3.7 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5)

  The above components except for ferrite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Carrier A was obtained.

The thickness of the coating resin layer of the obtained carrier A was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 40% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that there was no exposed surface and it was uniformly coated and the surface was flat. The production yield at this time was 75%. Further, the electrical resistance of the carrier A was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2 × 10 ⁵ Ω · cm. The electric resistance value of the coating resin film was 5 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

[Production of Toner A]
As an example, the toner preparation example of the present invention will be described in detail, but the present invention is not limited in any way.

<First step>
-Preparation of dispersion liquid (1)-
Styrene ... 370 parts by weight n-butyl acrylate ... 30 parts by weight acrylic acid ...・ 8 parts by weight dodecanethiol ・ ・ ・ ・ ・ ・ 24 parts by weight carbon tetrabromide ・ ・ ・ ・ ・ ・ 4 parts by weight

  The above mixture was dissolved, and 6 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 10 Disperse in a flask with 550 parts by weight of ion-exchanged water, emulsify, and slowly mix for 10 minutes. Add 50 parts by weight of ion-exchanged water in which 4 parts by weight of ammonium persulfate is dissolved. After purging with nitrogen, the flask was heated with an oil bath until the contents reached 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours. As a result, a dispersion (1) was prepared by dispersing resin particles having an average particle size of 155 nm, a glass transition point of 59 ° C., and a weight average molecular weight (Mw) of 12,000.

-Preparation of dispersion liquid (2)-
Styrene ... 280 parts by weight n-butyl acrylate ... 120 parts by weight acrylic acid ...・ 8 parts by weight

  6 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 12 Disperse in a flask with 550 parts by weight of ion-exchanged water, emulsify, and slowly mix for 10 minutes. Add 50 parts by weight of ion-exchanged water in which 3 parts by weight of ammonium persulfate is dissolved. After purging with nitrogen, the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. The average particle size was 105 nm, and the glass transition point was 53. A dispersion liquid (2) was prepared by dispersing resin particles having a temperature average molecular weight (Mw) of 55,000.degree.

--Preparation of colorant dispersion (1)-
Carbon black: 50 parts by weight (Cabot Corporation: Mogal L)
Nonionic surfactant: 5 parts by weight (manufactured by Sanyo Chemical Co., Ltd .: Nonipol 400)
Ion-exchanged water ... 200 parts by weight

  The above is mixed, dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Turrax T50) to disperse a colorant (carbon black) having an average particle diameter of 250 nm (carbon black) 1) was prepared.

-Preparation of release agent dispersion (1)-
50 parts by weight of paraffin wax (manufactured by Nippon Seiwa Co., Ltd .: HNP0190, melting point 85 ° C.)
Cationic surfactant ... 5 parts by weight (manufactured by Kao Corporation: Sanisol B50)
Ion-exchanged water ... 200 parts by weight

  The above was heated to 95 ° C. and dispersed using a homogenizer (IKA: Ultra Turrax T50), and then dispersed with a pressure discharge homogenizer to disperse a release agent having an average particle size of 550 nm. A release agent dispersion (1) was prepared.

--Preparation of aggregated particles--
Dispersion (1) ... 120 parts by weight Dispersion (2) ... 80 parts by weight Colorant dispersion (1) ... 30 parts by weight release agent dispersion (1) 40 parts by weight cationic surfactant 1.5 parts by weight (Kao ( Co., Ltd .: SANISOL B50)

The above was mixed and dispersed in a round stainless steel flask using a homogenizer (manufactured by IKA: Ultra Turrax T50), and then heated to 48 ° C. while stirring the inside of the flask in an oil bath for heating. After maintaining at 48 ° C. for 30 minutes, observation with an optical microscope confirmed that aggregated particles (volume: 95 cm ³ ) having an average particle diameter of about 5 μm were formed.

<Second step>
--Preparation of adhered particles--
Here, 60 parts by weight of the dispersion liquid (1) as the resin-containing fine particle dispersion liquid was gradually added. In addition, the volume of the resin particle contained in the dispersion liquid (1) is 25 cm ³ . And the temperature of the heating oil bath was raised to 50 degreeC, and was hold | maintained for 1 hour. When observed with an optical microscope, it was confirmed that adhered particles having an average particle diameter of about 5.7 μm were formed.

<Third step>
Thereafter, after adding 3 parts by weight of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC), the stainless steel flask was sealed, and stirring was continued using a magnetic seal. Heated to 0 ° C. and held for 3 hours. After cooling, the reaction product was filtered, sufficiently washed with ion exchange water, and then dried to obtain an electrostatic charge image developing toner.

<Evaluation>
The obtained electrostatic charge image developing toner A was measured to have a volume average particle size of 5.8 μm. Further, the average value of the shape factor SF1 of the toner was 135.

  Similarly, various color toners were prepared using benzidine yellow pigment # 17 as yellow, carmine 6B as magenta, and phthalocyanine blue as cyan.

  The average particle diameter and shape factor were substantially the same as those of the above black toner.

In order to improve the chargeability and transferability, an appropriate amount of the toner is added to the toner using inorganic fine particles such as 2.0 wt% silica having a volume average particle diameter of 10 to 150 nm and about 1.0 wt% titanium oxide (titania) as external additives. In addition, 3 parts by weight of the toner A was mixed with 100 parts by weight of carrier A having a volume average particle diameter of 35 μm to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2 × 10 ⁵ Ω · cm. The electric resistance value of the coating resin film was 5 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

  Further, since the BET specific surface area was 0.079 and the true spherical equivalent surface area was 0.032, the surface roughness of the carrier was 2.5.

(Example 2)
[Manufacture of carrier B]
100 parts by weight of ferrite (manufactured by Dowa Iron Industries Co., Ltd., DFC 350-295, volume average particle size 50 μm, sphericity 1.198, surface roughness 4.17, magnetization value 76 emu / g (1 kOe))
Toluene 10.3 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.1 parts by weight Perfluorooctylethyl methacrylate-methyl methacrylate copolymer (Copolymerization ratio 40:60, weight average molecular weight 50,000) 0.3 parts by weight of acicular conductive powder (antimony-doped tin oxide-coated titanium oxide) 2.8 parts by weight (Ishihara Sangyo Co., Ltd., HJ-1, electricity Resistance 5 × 10 ⁴ Ω · cm, fiber length 0.08 μm, fiber diameter 0.02 μm, aspect ratio 4)

  The above components except for ferrite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing type kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 75 μm. Carrier B was obtained.

The thickness of the coating resin layer of the obtained carrier B was 0.9 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 30% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that there was no exposed surface and it was uniformly coated and the surface was flat. The production yield at this time was 90%. The electric resistance value of the carrier B in the form of a magnetic brush was measured and extrapolated to an electric field of 10 ⁴ V / cm, and the electric resistance value was 6 × 10 ⁶ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 7 × 10 ⁶ Ω · cm at an electric field of 100 V / cm.

[Production of Toner B]
In substantially the same manner as in Example 1,
<First step>
--- Preparation of dispersion-
Styrene ... 370 parts by weight n-butyl acrylate ... 30 parts by weight acrylic acid ...・ 8 parts by weight dodecanethiol ・ ・ ・ ・ ・ ・ 24 parts by weight carbon tetrabromide ・ ・ ・ ・ ・ ・ 4 parts by weight

  The above mixture was dissolved, and 6 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 10 50 parts by weight of ion-exchanged water having 3.7 parts by weight of ammonium persulfate dissolved therein is dispersed in a flask, emulsified and slowly mixed for 10 minutes. Was added, and the atmosphere in the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and the emulsion polymerization was continued for 5 hours. As a result, a dispersion was prepared by dispersing resin particles having an average particle diameter of 150 nm, a glass transition point of 59 ° C., and a weight average molecular weight (Mw) of 28,000.

  The same colorant dispersion (1) and release agent dispersion (1) as in Example 1 were used.

--Preparation of aggregated particles--
Dispersion ... 200 parts by weight Colorant dispersion (1) ... 30 parts by weight Release agent dispersion (2) ... ... 40 parts by weight cationic surfactant ... 1.5 parts by weight (manufactured by Kao Corporation: Sanisol B50)

The above was mixed and dispersed in a round stainless steel flask using a homogenizer (manufactured by IKA: Ultra Turrax T50), and then heated to 48 ° C. while stirring the inside of the flask in an oil bath for heating. After maintaining at 48 ° C. for 30 minutes, it was confirmed by observation with an optical microscope that aggregated particles (volume: 96 cm ³ ) having an average particle diameter of about 4.9 μm were formed.

<Second step>
--Preparation of adhered particles--
Here, 60 parts by weight of the dispersion liquid as the resin-containing fine particle dispersion liquid was gradually added. The volume of the resin particles contained in the dispersion is 25 cm ³ . And the temperature of the heating oil bath was raised to 50 degreeC, and was hold | maintained for 1 hour. When observed with an optical microscope, it was confirmed that adhered particles having a volume average particle diameter of about 5.6 μm were formed.

<Third step>
Thereafter, after adding 3 parts by weight of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC), the stainless steel flask was sealed, and stirring was continued using a magnetic seal. Heated to 0 ° C. and held for 3 hours. Then, after cooling, the reaction product was filtered, washed thoroughly with ion exchange water, and then dried to obtain an electrostatic image developing toner B.

<Evaluation>
The obtained electrostatic charge image developing toner B was measured to have a volume average particle size of 5.7 μm. Further, the average value of the shape of the toner was 133.

  In the same manner as in Example 1, various color toners were prepared according to Example 2 using benzidine yellow pigment # 17 as yellow, carmine 6B as magenta, and phthalocyanine blue as cyan.

  The average particle diameter and shape factor were substantially the same as those of the above black toner.

In order to improve the chargeability and transferability, an appropriate amount of the toner is added to the toner using inorganic fine particles such as 2.0 wt% silica having a volume average particle diameter of 10 to 150 nm and about 1.0 wt% titanium oxide (titania) as external additives. In addition, 100 parts by weight of carrier B having an average particle diameter of 50 μm was mixed with 2 parts by weight of toner B to obtain a developer. The electric resistance was measured in the form of a magnetic brush, and the electric resistance value when extrapolating to an electric field of 10 ⁴ V / cm was 2.2 × 10 ⁵ Ω · cm. Moreover, the electric resistance value of the coating resin film was 5.3 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

  Further, since the BET specific surface area was 0.081 and the true spherical equivalent surface area was 0.032, the surface roughness of the carrier was 2.53.

(Example 3)
[Manufacture of Carrier C]
Magnetite of Example 1 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive Powder (antimony-doped tin oxide coated titanium oxide) 2.8 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., FT-1000, electrical resistance 1 × 10 Ω · cm, fiber length 1.7 μm, fiber diameter 0.1 μm, aspect ratio 17)
Spherical conductive powder (oxygen deficient tin oxide-coated barium sulfate) 0.9 parts by weight (Mitsui Metals, Pastorran TYPE-IV, electric resistance 6 × 10 ⁴ Ω · cm, volume average particle size 0.1 μm)

  The above components except for magnetite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and magnetite are put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Carrier C was obtained.

The thickness of the coating resin layer of the obtained carrier C was 0.7 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 30% by volume. The content of oxygen-deficient tin oxide-coated barium sulfate was 10% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that there was no exposed surface and it was uniformly coated and the surface was flat. The production yield at this time was 75%. Further, the electrical resistance of the carrier C was measured in the form of a magnetic brush, and the electrical resistance value when extrapolating up to an electric field of 10 ⁴ V / cm was 5 × 10 ⁴ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 6 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

100 parts by weight of carrier C having a volume average particle diameter of 35 μm was mixed with 3 parts by weight of the toner of Example 2 to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2.1 × 10 ⁵ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 4.7 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

  Furthermore, since the BET specific surface area was 0.077 and the true spherical equivalent surface area was 0.032, the surface roughness of the carrier was 2.41.

Example 4
[Manufacture of carrier D]
Magnetite of Example 1 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive Powder (antimony-doped tin oxide coated titanium oxide) 2.8 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., FT-1000, electrical resistance 1 × 10 Ω · cm, fiber length 1.7 μm, fiber diameter 0.1 μm, aspect ratio 17)
0.9 parts by weight of spherical conductive powder (oxygen-deficient tin oxide-coated barium sulfate) (Made by Mitsui Kinzoku Co., Ltd., Pastorran TYPE-IV, electric resistance 6 × 10 ⁴ Ω · cm, volume average particle size 0.1 μm)

  The above components except for magnetite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and magnetite are put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Carrier D was obtained.

The thickness of the coating resin layer of the obtained carrier D was 0.7 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 30% by volume. The content of oxygen-deficient tin oxide-coated barium sulfate was 10% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that there was no exposed surface and it was uniformly coated and the surface was flat. The production yield at this time was 75%. Furthermore, the electrical resistance of the carrier D was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 5 × 10 ⁴ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 6 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

100 parts by weight of carrier C having a volume average particle diameter of 35 μm was mixed with 3 parts by weight of the toner of Example 2 to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2.1 × 10 ⁵ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 4.7 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

  Furthermore, since the BET specific surface area was 0.273 and the true spherical equivalent surface area was 0.045, the surface roughness of the carrier was 6.07.

(Comparative Example 1)
[Manufacture of Carrier E]
Magnetite 100 parts by weight (manufactured by Fuji Electric Chemical Co., Ltd., MX030A, volume average particle size 50 μm, sphericity 1.230, surface roughness 1.61, magnetization value 82 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (antimony-doped tin oxide coating) Titanium oxide) 3.7 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5)

  The above components except for magnetite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and magnetite are put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 75 μm. Carrier E was obtained.

The thickness of the coating resin layer of the obtained carrier E was 0.9 μm. The content of antimony-doped tin oxide-coated potassium titanate was 40% by volume. When this carrier was observed with a scanning electron microscope, it was uniformly coated without an exposed surface, but many large irregularities on the surface of the core material were observed on the carrier surface. The production yield at this time was 50%. The electric resistance of the carrier E was measured in the form of a magnetic brush, and the electric resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 4 × 10 ⁵ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 8 × 10 ⁵ Ω · cm at an electric field of 100 V / cm.

  Further, since the BET specific surface area was 0.308 and the true spherical equivalent surface area was 0.041, the surface roughness of the carrier was 7.51.

(Comparative Example 2)
[Manufacture of Carrier F]
Magnetite 100 parts by weight (manufactured by Fuji Electric Chemical Co., Ltd., MO2-FX50-5, volume average particle size 50 μm, sphericity 1.248, surface roughness 1.58, magnetization value 82 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.1 parts by weight perfluorooctylethyl methacrylate-methyl methacrylate copolymer (Copolymerization ratio 40:60, weight average molecular weight 50,000) 0.3 parts by weight of acicular conductive powder (antimony-doped tin oxide-coated titanium oxide) 2.8 parts by weight (Ishihara Sangyo Co., Ltd., FT-1000, electricity Resistance 1 × 10Ω ・ cm, fiber length 1.7μm, fiber diameter 0.1μm, aspect ratio 17)

  The above components except for magnetite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and magnetite are put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 75 μm. Carrier F was obtained.

The thickness of the coating resin layer of the obtained carrier F was 0.9 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 30% by volume. When this carrier was observed with a scanning electron microscope, it was uniformly coated without an exposed surface, but many large irregularities on the surface of the core material were observed on the carrier surface. The production yield at this time was 53%. When the electric resistance of the carrier F was measured in the form of a magnetic brush and extrapolated to an electric field of 10 ⁴ V / cm, the electric resistance value was 5 × 10 ⁴ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 8 × 10 ⁴ Ω · cm at an electric field of 100 V / cm.

  Further, since the BET specific surface area was 0.251 and the true spherical equivalent specific surface area was 0.035, the surface roughness of the carrier was 7.17.

(Comparative Example 3)
[Manufacture of carrier G]
Magnetite 100 parts by weight (manufactured by Fuji Electric Chemical Co., Ltd., MO2-FX50-5, volume average particle size 50 μm, sphericity 1.248, surface roughness 1.58, magnetization value 82 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.1 parts by weight perfluorooctylethyl methacrylate-methyl methacrylate copolymer (Copolymerization ratio 40:60, weight average molecular weight 50,000) 0.3 parts by weight of acicular conductive powder (antimony-doped tin oxide-coated titanium oxide) 2.8 parts by weight (Ishihara Sangyo Co., Ltd., FT-1000, electricity Resistance 1 × 10Ω ・ cm, fiber length 1.7μm, fiber diameter 0.1μm, aspect ratio 17)

  The above components except for magnetite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and magnetite are put in a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 75 μm. Carrier G was obtained.

The thickness of the coating resin layer of the obtained carrier G was 0.9 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 30% by volume. When this carrier was observed with a scanning electron microscope, it was uniformly coated without an exposed surface, but many large irregularities on the surface of the core material were observed on the carrier surface. The production yield at this time was 53%. The electric resistance of the carrier G in the form of a magnetic brush was measured, and the electric resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 5 × 10 ⁴ Ω · cm. Moreover, the electrical resistance value of the coating resin film was 8 × 10 ⁴ Ω · cm at an electric field of 100 V / cm.

  Furthermore, since the BET specific surface area was 0.288 and the true sphere equivalent specific surface area was 0.035, the surface roughness of the carrier was 8.2.

[Production yield]
Table 1 shows the production yields of the carriers obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The production yield is the ratio of the amount of carrier obtained after sieving to the amount of carrier core material before coating.

(Production of Toner C for Comparative Example)
100 parts by weight of linear polyester resin (linear polyester obtained from terephthalic acid / bisphenol A and ethylene oxide adduct / cyclohexanedimethanol: Tg = 62 ° C., Mn = 4,000, Mw = 12,000, acid value = 12, hydroxyl value = 25)
3 parts by weight of carbon black (cabot company: Mogal L) as a black pigment

  The above mixture was kneaded with an extruder, pulverized with a jet mill, and then dispersed with an air classifier. <Evaluation> The obtained electrostatic charge image developing toner was measured to have a volume average particle size of 5 0.7 μm. Further, a black colored particle toner C having an average value of 157 for the toner was obtained.

  Similarly, various color toners were prepared using benzidine yellow pigment # 17 as yellow, carmine 6B as magenta, and phthalocyanine blue as cyan. By pulverization / classification, the average particle diameter and shape factor were almost the same as those of the above black toner.

[Image quality evaluation]
100 parts by weight of the carrier obtained in Examples 1 to 3 and Comparative Examples 1 to 3 and 3 parts by weight of the toner obtained in Examples 1 to 2 and Comparative Example were mixed to prepare a developer.

  For these developers, an electrophotographic copying machine (manufactured by Fuji Xerox Co., Ltd., DocuCentre Color 500 printer) is used, and the evaluation environment is low temperature and low humidity (10 ° C., 15% RH), normal temperature and normal humidity (22 ° C., 55% RH). ) And high temperature and high humidity (28 ° C., 85% RH), respectively, and a copy test was conducted.

(coverage)
A solid image (20 mm x 20 mm) is printed from a halftone of 5% to 100% coverage, and the coverage of the output image is measured with a Macbeth densitometer. The closer to the input 10% to 100% coverage, the better Judged that there was.

  Judgment criteria are almost reproduced as follows:... 5% to 100% coverage. Δ: Almost up to 10-60% coverage. X: Almost no reproduction.

(Edge defect)
A chart in which a solid image of 100% coverage (10 mm × 10 mm) is arranged at the center of a halftone image (20 mm × 20 mm) of 10% to 60% coverage is printed, and the reproducibility of the end portion of the output image is printed Was determined visually. Judgment was represented by the worst value in a halftone image of 10% to 60% coverage.

  Judgment criteria are:... The edge part of the halftone output image is reproduced. Δ: Slightly visible portions are seen at the edge of the halftone output image. X: The edge part of the halftone output image is clearly thinned.

(Fog)
The toner fog on the background of the image was evaluated by visual observation and ranked in three stages. ○ indicates no fogging, △ indicates slight fogging, but there is no practical problem, and × indicates severe fogging.

  The evaluation was performed on the first and 50,000th copies under normal temperature and humidity, and on the first copy under low temperature and low humidity and high temperature and high humidity. The results are shown in Tables 1 to 12.

  When the carriers A, B, C, and D of the present invention were used, excellent image quality was obtained and stable against deterioration with time and environmental fluctuation. Moreover, the manufacturing yield also showed a high value. On the other hand, the carrier E of Comparative Example 1, the carrier F of Comparative Example 2, and the carrier G of Comparative Example 3 are excellent in stability against environmental fluctuations because they use needle-shaped conductive powder. Since no material was used, the charge amount decreased at the 50,000th sheet even at room temperature and normal humidity, the image density was high, and fogging was observed. This was particularly bad for the carrier F having a relatively small content of acicular conductive powder.

  Further, the present invention will be specifically described with reference to examples and comparative examples. Note that the present invention is not limited to these.

(Example 5)
[Manufacture of carrier core]
The raw materials are appropriately blended so as to be 50.0 mol% in terms of MnO and 50.0 mol% in terms of Fe ₂ O ₃ , added with water and mixed while being pulverized for 24 hours with an oven dryer. After drying, the mixture was heated at 950 ° C. for 6 hours, cooled and taken out, and water was added thereto, and the mixture was pulverized again into particles of 0.1 μm or less with a ball mill over 24 hours.

  While maintaining and controlling the water content of the slurry at 90%, 5 parts by weight of a water-soluble binder (carboxymethylcellulose) was added to 100 parts by weight of the carrier raw material, mixed with a propeller type stirrer, and adjusted to 180 ° C. dry air with a pump. It put into the rotary disk atomizer type play dryer, and it dried, granulating. At this time, the amount of water, the number of revolutions of the disk atomizer, and the amount of liquid delivered by the pump were adjusted so that the raw material particles had a particle size of 0.5 to 5 μm.

  The raw material particles were heated at 950 ° C. for 6 hours, then cooled and taken out to obtain carrier core surface protrusions. Next, 10 parts by weight of a water-soluble binder (carboxymethyl cellulose) is added to 100 parts by weight of the carrier raw material while maintaining and controlling the water content of the slurry at 70%, and mixed with a propeller type stirrer and dried at 180 ° C. with a pump. It was put into a rotary disk atomizer type play dryer adjusted to, and dried while granulating. At this time, the amount of water, the number of revolutions of the disk atomizer, and the pumping amount were adjusted so that the raw material particles had a particle size of 5 to 100 μm.

The particles (PVA) and a water-soluble binder (carboxymethylcellulose) are added to the particles as appropriate and granulated, followed by high-temperature treatment, and approximately spherical magnetic particles of 0.5 to 5 μm and substantially spherical magnetic materials of 5 to 100 μm. In order to adjust the resistance, an oxygen concentration of 3% is prepared for the purpose of adjusting the resistance. After heating at 1290 ° C. for 8 hours in the atmosphere of the above, cooling, and crushing / classifying, the surface of the magnetic core material has a protrusion of approximately 5 to 5 μm of substantially hemispherical magnetic particles. The core material A of the carrier was obtained from the magnetic core material. When the magnetization characteristics and the like of the core material A of this carrier were measured, the average particle size was 35.5 μm and the magnetization value was 71 emu / g (1 kOe). Further, when the surface of the carrier core was observed with an SEM and the BET adsorption surface property was observed, the surface had fine irregularities, and the BTE value was 0.056 g / cm ² .

[Conductive coating of carrier core]
Carrier core material A 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (Antimony-doped tin oxide-coated titanium oxide) 3.7 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5 )

  The above components except for the carrier core material A were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Carrier H was obtained.

The thickness of the coating resin layer of the obtained carrier H was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 40% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier core material A, it was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Furthermore, the electrical resistance value of the carrier H measured in the form of a magnetic brush and extrapolated to an electric field of 10 ⁴ V / cm was 2 × 10 ⁵ Ω · cm.

[Production of Toner D]
As an example, the toner preparation example of the present invention will be described in detail, but the present invention is not limited in any way.

<First step>
-Preparation of dispersion liquid (1)-
Styrene ... 370 parts by weight n-butyl acrylate ... 30 parts by weight acrylic acid ...・ 8 parts by weight dodecanethiol ・ ・ ・ ・ ・ ・ 24 parts by weight carbon tetrabromide ・ ・ ・ ・ ・ ・ 4 parts by weight

  The above mixture was dissolved, and 6 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 10 Disperse in a flask with 550 parts by weight of ion-exchanged water, emulsify, and slowly mix for 10 minutes. Add 50 parts by weight of ion-exchanged water in which 4 parts by weight of ammonium persulfate is dissolved. After purging with nitrogen, the flask was heated with an oil bath until the contents reached 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours. As a result, a dispersion (1) was prepared by dispersing resin particles having a volume average particle size of 155 nm, a glass transition point of 59 ° C., and a weight average molecular weight (Mw) of 12,000.

-Preparation of dispersion liquid (2)-
Styrene ... 280 parts by weight n-butyl acrylate ... 120 parts by weight acrylic acid ...・ 8 parts by weight

  6 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 12 Disperse in a flask with 550 parts by weight of ion-exchanged water, emulsify, and slowly mix for 10 minutes. Add 50 parts by weight of ion-exchanged water in which 3 parts by weight of ammonium persulfate is dissolved. Then, after nitrogen substitution, the contents in the flask were stirred and heated in an oil bath until the temperature reached 70 ° C., and emulsion polymerization was continued for 5 hours. The volume average particle size was 105 nm, and the glass transition point was A dispersion liquid (2) was prepared by dispersing resin particles having a weight average molecular weight (Mw) of 55,000 at 53 ° C.

--Preparation of colorant dispersion (1)-
・ C. I. Pig. Y-185 (coloring agent manufactured by BASF Corporation): 40 parts by weight, anionic surfactant (manufactured by Daiichi Kogyo Seiyaku: Neogen RK): 10 parts by weight, ion-exchanged water: 490 parts by weight

  The above is mixed, dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Turrax T50), and a colorant (CI Pig. Y-185) having a volume average particle diameter of 100 nm is dispersed. A colorant dispersion (1) was prepared.

-Preparation of release agent dispersion (1)-
50 parts by weight of paraffin wax (manufactured by Nippon Seiwa Co., Ltd .: HNP0190, melting point 85 ° C.)
Cationic surfactant ... 5 parts by weight (manufactured by Kao Corporation: Sanisol B50)
Ion-exchanged water ... 200 parts by weight

  The above was heated to 95 ° C. and dispersed using a homogenizer (IKA: Ultra Turrax T50), and then dispersed with a pressure discharge homogenizer to disperse a release agent having an average particle size of 550 nm. A release agent dispersion (1) was prepared.

--Preparation of aggregated particles--
Dispersion (1) ... 120 parts by weight Dispersion (2) ... 80 parts by weight Colorant dispersion (1) ... 30 parts by weight release agent dispersion (1) 40 parts polyaluminum chloride 0.2 parts by weight

  The above components were thoroughly mixed and dispersed in a round stainless steel flask using Ultra Turrax (T50, manufactured by IKA), and 1N nitric acid was added to adjust the pH of the dispersion to 2.5. Subsequently, the dispersion operation was continued with an ultra turrax until no dispersed particles exceeded 2 μm, and the flask was heated to 50 ° C. with stirring in an oil bath for heating. Hold at 50 ° C. for 120 minutes. At this time, the particle diameter in the flask was measured and found to be 3.2 μm. Thereafter, 30 parts by weight of the resin fine particle dispersion was gradually added and held for 180 minutes. At this time, the particle diameter in the flask was measured and found to be 3.6 μm. Thereafter, the pH of the system was adjusted to 6.5 with a 0.5 N aqueous sodium hydroxide solution, and then the stainless steel flask was sealed and heated to 96 ° C. while continuing to stir using a magnetic seal for 5 hours. Retained. After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 liters of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate was 7.01, the electric conductivity was 9.8 μS / cm, and the surface tension was 71.1 Nm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. It was. Next, freeze-drying was continued for 12 hours to obtain Yellow toner particles of Example 1.

  Similarly, instead of the colorant dispersion (Y), the Y pigment of the colorant dispersion is changed to C.I. I. Pig. Instead of the colorant dispersion (M) and the colorant dispersion (Y), which are R-283 (manufactured by Sanyo Color Co., Ltd.), the Y pigment of the colorant dispersion is changed to C.I. I. Pig. Blue 15: 3 Ciba Gaigegi Co., Ltd.) Colorant dispersion (C) and the colorant dispersion Y (Y) pigment was replaced with Carbon Black BPL (Cabot). Magenta, Cyan and black toner particles were prepared using a colorant dispersion (black). When the volume average particle diameter of the toner particles was measured, the Magenta toner was 3.5 μm, the Cyan toner was 3.5 μm, and the black toner was 3.3 μm.

In order to improve the chargeability and transferability, an appropriate amount of inorganic fine particles such as 2.0 wt% silica having an average particle diameter of 10 to 150 nm and about 1.0 wt% titanium oxide (titania) is externally added to the toner as an external additive. A developer was prepared by mixing 3 parts by weight of the toner with 100 parts by weight of carrier H having an average particle size of 35 μm. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2 × 10 ⁵ Ω · cm. Further, 8 parts by weight of the toner D was mixed with 100 parts by weight of carrier H having an average particle diameter of 35 μm to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 2.3 × 10 ⁵ Ω · cm.

  Thus, the developer resistance value of the developer of the present invention does not change so much even if the toner concentration changes.

(Example 6)
[Manufacture of carrier core]
While appropriately mixing the raw materials so as to be 40.0 mol% in terms of MnO, 10.0 mol% in terms of MgO, and 50.0 mol% in terms of Fe ₂ O ₃ , adding water and grinding for 24 hours with a ball mill After mixing and drying in an oven drier, heating at 950 ° C. for 6 hours, cooling and taking out, water is added thereto, and particles are again reduced to 0.1 μm or less in a ball mill over 24 hours. It grind | pulverized so that it might become.

  While maintaining and controlling the water content of the slurry at 90%, 5 parts by weight of a water-soluble binder (carboxymethylcellulose) was added to 100 parts by weight of the carrier raw material, mixed with a propeller type stirrer, and adjusted to 180 ° C. dry air with a pump. It put into the rotary disk atomizer type play dryer, and it dried, granulating. At this time, the amount of water, the number of revolutions of the disk atomizer, and the amount of liquid delivered by the pump were adjusted so that the raw material particles had a particle size of 0.5 to 5 μm.

  The raw material particles were heated at 950 ° C. for 6 hours, then cooled and taken out to obtain carrier core surface protrusions. Next, 10 parts by weight of a water-soluble binder (carboxymethyl cellulose) is added to 100 parts by weight of the carrier raw material while maintaining and controlling the water content of the slurry at 70%, and mixed with a propeller type stirrer and dried at 180 ° C. with a pump. It was put into a rotary disk atomizer type play dryer adjusted to, and dried while granulating. At this time, the amount of water, the number of revolutions of the disk atomizer, and the pumping amount were adjusted so that the raw material particles had a particle size of 5 to 100 μm.

The particles (PVA) and a water-soluble binder (carboxymethylcellulose) are added to the particles as appropriate and granulated, followed by high-temperature treatment, and approximately spherical magnetic particles of 0.5 to 5 μm and substantially spherical magnetic materials of 5 to 100 μm. In order to adjust the resistance, an oxygen concentration of 3% is prepared for the purpose of adjusting the resistance. After heating at 1290 ° C. for 8 hours in the atmosphere of the above, cooling, and crushing / classifying, the surface of the magnetic core material has a protrusion of approximately 5 to 5 μm of substantially hemispherical magnetic particles. The carrier core material B was obtained from the magnetic core material. When the magnetization characteristics and the like of the core material B of this carrier were measured, the average particle size was 35.5 μm and the magnetization value was 66 emu / g (1 kOe). Further, when the surface of the carrier core was observed with an SEM and the BET adsorption surface property was observed, the surface had fine irregularities, and the BTE value was 0.055 g / cm ² .

[Conductive coating of carrier core]
Carrier core material B 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (Antimony-doped tin oxide-coated titanium oxide) 3.7 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5 )

  The above components except for the carrier core material B were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Carrier I was obtained.

The thickness of the coating resin layer of the obtained carrier I was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 40% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier core material B, was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Further, the electrical resistance of the carrier I was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 3.1 × 10 ⁵ Ω · cm.

100 parts by weight of carrier I having a volume average particle diameter of 35 μm was mixed with 3 parts by weight of toner D of Example 5 to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 3.7 × 10 ⁵ Ω · cm. Further, 100 parts by weight of carrier H having an average particle size of 35 μm was mixed with 8 parts by weight of toner D to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 4 × 10 ⁵ Ω · cm.

  As described above, the developer resistance value of the developer of the present invention did not change much even when the toner concentration was changed.

(Example 7)
Using the carrier core material B used in Example 6, a carrier J with a slightly reduced amount of conductive material was prepared in the same manner as in Example 6.

[Conductive coating of carrier core]
Carrier core material B 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (Antimony-doped tin oxide-coated titanium oxide) 3.2 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5 )

  The above components except for the carrier core material B were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. To get Career J.

The thickness of the coating resin layer of the obtained carrier J was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 50% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier core material B, was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Further, the electrical resistance of the carrier B was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 6.7 × 10 ⁴ Ω · cm.

A developer was prepared by mixing 3 parts by weight of the toner D of Example 5 with 100 parts by weight of carrier J having a volume average particle diameter of 35 μm. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 8.2 × 10 ⁴ Ω · cm. Further, 100 parts by weight of carrier J having a volume average particle size of 35 μm was mixed with 8 parts by weight of toner D to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 9.1 × 10 ⁴ Ω · cm.

  As described above, the developer resistance value of the developer of the present invention did not change much even when the toner concentration was changed.

(Example 8)
Using the carrier core material B used in Example 6, a carrier K in which the amount of the conductive material was increased was produced in the same manner as in Example 6.

[Conductive coating of carrier core]
Carrier core material B 100 parts by weight Toluene 8.8 parts by weight Diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight acicular conductive powder (Antimony-doped tin oxide-coated titanium oxide) 4.2 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5 )

  The above components except for the carrier core material B were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. To get carrier K.

The thickness of the coating resin layer of the obtained carrier K was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 50% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier core material B, was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Furthermore, the electrical resistance of the carrier K was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 6.7 × 10 ⁴ Ω · cm.

A developer was prepared by mixing 3 parts by weight of the toner D of Example 5 with 100 parts by weight of carrier K having an average particle diameter of 35 μm. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 8.2 × 10 ⁴ Ω · cm. Further, 100 parts by weight of carrier K having an average particle diameter of 35 μm was mixed with 8 parts by weight of toner D to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 9.1 × 10 ⁴ Ω · cm.

  As described above, the developer resistance value of the developer of the present invention did not change much even when the toner concentration was changed.

(Comparative Example 4)
[Manufacture of Carrier L]
100 parts by weight of ferrite (manufactured by Dowa Iron Industries Co., Ltd., DFC450-320, average particle size 35 μm, sphericity 1.196, surface roughness 4.15, magnetization value 73 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (antimony-doped tin oxide coating) Titanium oxide) 3.7 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5)

  The above components except for ferrite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Thus, Comparative Example Carrier L was obtained.

The thickness of the coating resin layer of the obtained comparative example carrier L was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 40% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier L of the comparative example, and it was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Furthermore, the electrical resistance value of the carrier C of Comparative Example was measured in the form of a magnetic brush and extrapolated to an electric field of 10 ⁴ V / cm, and was 2.1 × 10 ⁵ Ω · cm.

100 parts by weight of Comparative Example Carrier L having an average particle size of 35 μm was mixed with 3 parts by weight of Toner D of Comparative Example 4 to obtain a developer. The electric resistance was measured in the form of a magnetic brush, and the electric resistance value when extrapolating to an electric field of 10 ⁴ V / cm was 2.2 × 10 ⁵ Ω · cm. Further, 100 parts by weight of Comparative Example Carrier L having an average particle diameter of 35 μm was mixed with 8 parts by weight of toner D to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 8.9 × 10 ⁶ Ω · cm.

  As described above, the developer prepared with the carrier L of the comparative example has a developer resistance value greatly changed by the change of the toner density.

(Comparative Example 5)
[Manufacture of Carrier M]
100 parts by weight of ferrite (manufactured by Dowa Iron Industries Co., Ltd., DFC450-320, average particle size 35 μm, sphericity 1.196, surface roughness 4.15, magnetization value 73 emu / g (1 kOe))
Toluene 8.8 parts by weight diethylaminoethyl methacrylate-styrene-methyl methacrylate copolymer (copolymerization ratio 2:20:78, weight average molecular weight 50,000) 1.2 parts by weight of acicular conductive powder (antimony-doped tin oxide coating) Titanium oxide) 4.2 parts by weight (manufactured by Ishihara Sangyo Co., Ltd., HI-2, electrical resistance 5 × 10 ⁴ Ω · cm, fiber length 0.3 μm, fiber diameter 0.06 μm, aspect ratio 5)

  The above components except for ferrite were dispersed in a sand mill for 1 hour to prepare a coating resin layer forming solution. Next, this coating resin layer forming solution and ferrite are put into a vacuum degassing kneader and stirred for 20 minutes while reducing the pressure at a temperature of 60 ° C. to form a coating resin layer, and further sieved with a sieve having an opening of 45 μm. Thus, Comparative Example Carrier M was obtained.

The thickness of the coating resin layer of the obtained Comparative Example carrier M was 0.6 μm. The content of the antimony-doped tin oxide-coated titanium oxide was 40% by volume. When this carrier was observed with a scanning electron microscope, it was confirmed that the coating material was buried in the fine irregularities of the carrier F of the comparative example, it was uniformly coated without an exposed surface, and the surface was almost flat. . The production yield at this time was 75%. Furthermore, the electrical resistance value of the comparative example carrier F measured in the form of a magnetic brush and extrapolated to an electric field of 10 ⁴ V / cm was 6.1 × 10 ⁴ Ω · cm.

A developer was prepared by mixing 3 parts by weight of the toner D of Comparative Example 4 with 100 parts by weight of Comparative Example Carrier M having a volume average particle diameter of 35 μm. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 7.2 × 10 ⁴ Ω · cm. Further, 8 parts by weight of the toner D was mixed with 100 parts by weight of Comparative Example Carrier F having a volume average particle size of 35 μm to obtain a developer. The electrical resistance was measured in the form of a magnetic brush, and the electrical resistance value when extrapolated to an electric field of 10 ⁴ V / cm was 8.2 × 10 ⁶ Ω · cm.

  As described above, the developer prepared with the carrier of the comparative example has a developer resistance value greatly changed by a change in the toner density.

-Evaluation of electrostatic image developer-
Using the obtained electrostatic charge image developer, the image density when the weight per unit area of each toner is 2.5 g / m ² in an image forming apparatus (Fuji Xerox printer DocuCenter Color 500) is X When the density was measured with -Rite (manufactured by X-Rite), as shown in Table 13, stable image density and fogging of non-image sites were shown in a wide toner density region. Also, the resolution seen at 1 dot 1 off, and the halftone edge part of the low image density (the degree of image blur) is a very good and high quality color image in a wide toner density region. It was shown that there is.

  On the other hand, in the developer composed of the carrier of the comparative example, if the toner density fluctuates even slightly, the image density, resolution, and halftone reproduction greatly change.

  The evaluation criteria in Tables 13 and 14 below are as follows.

-Evaluation of maintenance performance of electrostatic charge image developer-
Using the obtained electrostatic charge image developer, the image forming apparatus (Fuji Xerox printer DCC500) printed 100000 prints and then evaluated in the same manner as in the previous examples. The initial image quality was maintained and it was very good.

  However, in Comparative Examples 4 and 5, the toner density dependence becomes larger and the toner density range, which is not a problem in image quality, is further narrowed. Table 14 summarizes the results.

  The evaluation criteria in Tables 13 and 14 below are as follows.

[Image density]
1.1 or less: x, 1.1 to 1.3: Δ, 1.3 or more: ◯.

[resolution]
Crush: x, looks blurry: Δ, clearly visible: o.

[Halftone end]
Disappear locally: x, faint: Δ, uniform: ○.

[Fog]
Clearly understood: ×, slightly present: Δ, inconspicuous: ○.

  Furthermore, the yellow toner in the present invention will be specifically described with reference to examples and comparative examples. Note that the present invention is not limited to these.

Example 9
A: Preparation of resin particle dispersion -Preparation of resin particle dispersion (1)-
Styrene: 270 parts by weight n-butyl acrylate: 30 parts by weight Acrylic acid: 5 parts by weight Dodecanethiol: 22 parts by weight Carbon tetrabromide: 3 parts by weight

  The components having the above composition were mixed and dissolved, and the solution was mixed with 7 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC). Disperse 11 parts by weight in a solution of 500 parts by weight of ion-exchanged water in a flask, emulsify, and slowly mix for 10 minutes while adding 2.5 parts by weight of ammonium persulfate (Wako Pure Chemical Industries, Ltd.) 50 parts by weight of a solution dissolved in exchange water was added. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. Thereafter, the reaction liquid was cooled to room temperature to prepare a resin particle dispersion liquid in which resin particles having a glass transition point of 61 ° C. and a weight average molecular weight of 25000 were dispersed.

B: Preparation of Colorant Dispersion-Preparation of Colorant Dispersion (Yellow)-
・ C. I. Pig. Y-185 (colorant manufactured by BASF Corporation): 40 parts by weight, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight, ion-exchanged water: 490 parts by weight

  The components having the above composition were mixed, dispersed for 10 minutes using a homogenizer (IKA, Ultra Turrax 750), and then allowed to stand overnight. Prepared. The colorant particles in the colorant dispersion (Y) have a 50% particle diameter of 50 nm, 70% or more of the colorant particles are in the range of 40-60 nm, and 200 nm coarse particles are 10% or less. Met.

-Preparation of colorant particle dispersion (Magenta)-
・ C. I. Pig. R-283 (manufactured by Sanyo Dye Co., Ltd.): 50 parts by weight, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight, ion-exchanged water: 490 parts by weight

  The components of the above composition were mixed and prepared under the same conditions as in the preparation of the colorant dispersion (Y).

  In the colorant dispersion (Magenta), the 50% by number particle size of the colorant particles is 45 nm, 70% by number or more of the colorant particles are in the range of 40 to 60 nm, and the coarse particles of 200 nm are 5% by number or less. Met.

-Preparation of Colorant Particle Dispersion (Cyan)-
・ C. I. Pig. B-15: 3: 50 parts by weight (manufactured by Ciba Geigy Co., Ltd.))
-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight-Ion exchange water: 490 parts by weight

  The components of the above composition were mixed and prepared under the same conditions as in the preparation of the colorant dispersion (Y).

  The colorant particles in the colorant dispersion (Cyan) have a particle number of 50% by number of 42 nm, 70% by number or more of the colorant particles are in the range of 40 to 60 nm, and 200 nm coarse particles are 5% by number or less. Met.

-Preparation of colorant particle dispersion (black)-
Carbon black BPL (manufactured by Cabot): 40 parts by weight Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku: Neogen RK): 10 parts by weight Ion-exchanged water: 490 parts by weight

  The components of the above composition were mixed and prepared under the same conditions as in the preparation of the colorant dispersion (Y).

  In the colorant dispersion (black), the 50% by number particle diameter of the colorant particles is 43 nm, 70% by number or more of the colorant particles are in the range of 40 to 60 nm, and the coarse particles of 200 nm are 5% by number or less. Met.

C: Preparation of Release Agent Dispersion-Preparation of Release Agent Dispersion-
Paraffin wax (Nippon Seiwa Co., Ltd .: HNP0190): 60 parts by weight Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight Ion-exchanged water: 300 parts by weight

  The components having the above composition were mixed and dispersed for 10 minutes using a homogenizer (manufactured by IKA, Ultra Turrax 750), followed by dispersion treatment with a pressure discharge homogenizer to obtain a release agent dispersion having a volume average particle diameter of 100 nm. It was.

(Aggregation process / toner creation)
-Resin particle dispersion: 140 parts by weight-Colorant dispersion (Y): 40 parts by weight-Release agent dispersion: 40 parts by weight-Polyaluminum chloride: 0.2 parts by weight

  The above components were thoroughly mixed and dispersed in a round stainless steel flask using Ultra Turrax (T50, manufactured by IKA), and 1N nitric acid was added to adjust the pH of the dispersion to 2.5. Subsequently, the dispersion operation was continued with an ultra turrax until no dispersed particles exceeded 2 μm, and the flask was heated to 50 ° C. with stirring in an oil bath for heating. Hold at 120C for 120 minutes. At this time, the particle diameter in the flask was measured and found to be 3.2 μm. Thereafter, 30 parts by weight of the resin fine particle dispersion was gradually added and held for 180 minutes. At this time, the particle diameter in the flask was measured and found to be 3.6 μm. Thereafter, the pH of the system was adjusted to 6.5 with a 0.5 N aqueous sodium hydroxide solution, and then the stainless steel flask was sealed and heated to 96 ° C. while continuing to stir using a magnetic seal for 5 hours. Retained. After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 liters of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate was 7.01, the electric conductivity was 9.8 μS / cm, and the surface tension was 71.1 Nm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. It was. Next, freeze-drying was continued for 12 hours to obtain Yellow toner particles of Example 1.

  Similarly, Magenta, Cyan and black toner particles are prepared using the colorant dispersion (M), the colorant dispersion (C), and the colorant dispersion (black) instead of the colorant dispersion (Y). did. When the volume average particle diameter of the toner particles was measured, the Magenta toner was 3.5 μm, the Cyan toner was 3.5 μm, and the black toner was 3.3 μm.

  The pigment concentration index values contained in the toner are Yellow toner 17, Magenta toner 22, Cyan toner 22 and black toner 16, respectively.

  When the colorant particles in the toner were observed with a transmission electron microscope, the number average coarse dispersion particles having a number average dispersion average particle diameter of 40 to 60 nm and 200 nm or more were 5 to 8% by number.

-Preparation of electrostatic image developer-
1 part by weight of hydrophobic silica (TS720: manufactured by Cabot) was added to 50 parts by weight of the electrostatic image developing toner, and blended in a sample mill. This blend was weighed so that the toner concentration would be 3% by weight with respect to a ferrite carrier having a volume average particle diameter of 50 μm coated with 1% by weight of polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) and stirred for 5 minutes with a ball mill. An electrostatic charge image developer was prepared by mixing.

-Evaluation of electrostatic image developer-
Using the obtained electrostatic charge image developer, the image density when the weight per unit area of each toner is 2.5 g / m ² in an image forming apparatus (Fuji Xerox printer—DocuCenter Color 500) When the color gamut was measured with X-Rite (635 made by X-Rite), a wide color gamut was shown as shown in Table 15 and FIG. Further, it was shown that the resolution viewed at 1 dot 1 off and the halftone edge portion with low image density were very good and high quality color images.

  Furthermore, when the image density was measured, it was 1.36 in a high temperature and high humidity environment (28 ° C., 85% RH) and 1.34 in a low temperature and low humidity environment (10 ° C., 30% RH), and there was no problem in practical use. It was a level. Moreover, it was favorable when visual evaluation was performed about the transparency of the fixed image on the obtained OHP transparent film.

(Comparative Example 6)
A: The resin particle dispersion was prepared in the same manner as in Example 1.

B: Preparation of Colorant Dispersion-Preparation of Colorant Dispersion (Yellow)-
・ C. I. Pig. Y-74: 40 parts by weight (manufactured by Sanyo Color Co., Ltd .: First Y102 colorant)
-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight-Ion exchange water: 190 parts by weight

  The components having the above composition were mixed, dispersed for 10 minutes using a homogenizer (manufactured by IKA, Ultra Turrax 750), and then allowed to stand overnight. Thereafter, a colorant dispersion (Yellow) was prepared through an optimizer (Sugino Machine Seisakusho). The colorant particles in the colorant dispersion (Y) have a 50% particle diameter of 150 nm, 70% or more of the colorant particles are in the range of 80 to 180 nm, and coarse particles of 200 nm or more are 10% by number. That was all.

  Similarly to Yellow, Cyan, Magenta, and black colorant dispersions were prepared using the various pigments of Example 1, and the particle size of the colorant particles in each dispersion was measured. The particle number of 50% by weight was 150 nm, 70% by weight or more of the colorant particles were in the range of 80 to 180 nm, and the coarse particles of 200 nm or more were in the range of 10% or more.

  (Aggregation step / preparation of toner) was also carried out in the same manner as in Example 9. The volume average particle diameter of each toner was 3.5 μm for Yellow toner, 3.5 μm for Magenta toner, 3.5 μm for Cyan toner, and 3.3 μm for black toner.

  The pigment concentration index values contained in the toner are Yellow toner 58, Magenta toner 58, Cyan toner 58, and black toner 55, respectively.

  When the colorant particles in the toner were observed with a transmission electron microscope, the number average dispersion average particle diameter was 80 to 180 nm, and coarse particles showing 200 nm or more were 15% by number.

  The electrostatic charge image developer was prepared and evaluated in the same manner as in Example 9. As a result, the color gamut was measured, and as shown in FIG. The color gamut is narrower than that of Example 9, and cannot be said to be a high-quality color image.

(Example 10)
A: The resin particle dispersion was prepared in the same manner as in Example 9.

B: Preparation of Colorant Dispersion-Preparation of Colorant Dispersion (Yellow)-
・ C. I. Pig. Y-185 (manufactured by BASF Corporation): 40 parts by weight, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 10 parts by weight, ion-exchanged water: 990 parts by weight

  The components having the above composition were mixed, dispersed for 10 minutes using a homogenizer (IKA, Ultra Turrax 750), and then allowed to stand overnight. Prepared. The colorant particles in the colorant dispersion (Y) have a particle number of 50% by number of 41 nm, 70% by number or more of the colorant particles are in the range of 40 to 60 nm, and 4% by number of coarse particles of 200 nm or more. It was the following.

  Similarly to Yellow, Cyan, Magenta, and black colorant dispersions were prepared using the various pigments of Example 1, and the particle size of the colorant particles in each dispersion was measured. The particle number of 50% by weight was 40 nm, 70% by number or more of the colorant particles were in the range of 40-60 nm, and the coarse particles of 200 nm or more were in the range of 5% by number or less.

  (Aggregation step / preparation of toner) was also carried out in the same manner as in Example 9. The volume average particle diameter of each toner was 3.5 μm for Yellow toner, 3.5 μm for Magenta toner, 3.5 μm for Cyan toner, and 3.3 μm for black toner.

  The pigment concentration index values contained in the toner are Yellow toner 13.3, Magenta toner 13.3, Cyan toner 13.3, and black toner 12.5, respectively.

  When the colorant particles in the toner were observed with a transmission electron microscope, the number average coarse dispersion particles having a number average dispersion average particle diameter of 40 to 60 nm and 200 nm or more were 5 to 8% by number.

-Preparation of electrostatic image developer-
1 part by weight of hydrophobic silica (TS720: manufactured by Cabot) was added to 50 parts by weight of the electrostatic image developing toner, and blended in a sample mill. This blend was weighed so that the toner concentration would be 3% by weight with respect to a ferrite carrier having a volume average particle diameter of 50 μm coated with 1% by weight of polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) An electrostatic charge image developer was prepared by mixing.

-Evaluation of electrostatic image developer-
Using the obtained electrostatic charge image developer, the image density when the weight per unit area of each toner is 2.5 g / m ² in an image forming apparatus (Fuji Xerox printer—DocuCenter Color 500) When the color gamut was measured with X-Rite (635, manufactured by X-Rite), a wide color gamut was shown as shown in FIG. In addition, it was shown that the resolution viewed at 1 dot 1 off and the halftone edge portion with low image density were very good and high quality color images.

  Further, when the image density was measured, it was 1.26 in a high temperature and high humidity environment (28 ° C., 85% RH), and 1.24 in a low temperature and low humidity environment (10 ° C., 30% RH), and there was no problem in practical use. It was a level. Moreover, it was favorable when visual evaluation was performed about the transparency of the fixed image on the obtained OHP transparent film.

(Example 11)
The toners of Comparative Example 6 and Example 10 were mixed and adjusted so that the total pigment concentration index was 10-25 as shown in Table 18. The numerical values shown in Table 18 are toner weight ratios.

  The preparation of the electrostatic charge image developer and the evaluation of the electrostatic charge image developer were tested in the same manner as in Example 9. As a result, a wide color gamut was obtained as shown in FIG. In addition, it was shown that the resolution viewed at 1 dot 1 off and the halftone edge portion with low image density were very good and high quality color images.

  Furthermore, when the image density was measured, it was 1.36 in a high temperature and high humidity environment (28 ° C., 85% RH) and 1.34 in a low temperature and low humidity environment (10 ° C., 30% RH), and there was no problem in practical use. It was a level. Moreover, it was favorable when visual evaluation was performed about the transparency of the fixed image on the obtained OHP transparent film.

(Example 12)
In the aggregation step / toner preparation step of Example 9, a transparent toner was prepared without adding a colored dispersion.

(Example 13)
The transparent toners of Comparative Example 6 and Example 12 were mixed and adjusted so that the total pigment concentration index was 10 to 25 as shown in Table 20. The numerical values shown in Table 20 are toner weight ratios.

  The preparation of the electrostatic image developer and the evaluation of the electrostatic image developer were tested in the same manner as in Example 9. As a result, a wide color gamut was obtained as shown in FIG. In addition, it was shown that the resolution viewed at 1 dot 1 off and the halftone edge portion with low image density were very good and high quality color images.

  Furthermore, when the image density was measured, it was 1.36 in a high temperature and high humidity environment (28 ° C., 85% RH) and 1.34 in a low temperature and low humidity environment (10 ° C., 30% RH), and there was no problem in practical use. It was a level. Moreover, it was favorable when visual evaluation was performed about the transparency of the fixed image on the obtained OHP transparent film.

  In particular, the greater the difference between the green and red color gamuts, the clearer the yellow color. As shown in FIGS. 2 to 6, the color gamut difference is slightly visible, but this slight difference is a large visual difference with the naked eye. For example, in a fruit lemon print image, if the color gamut is narrow, an image such as an unripe lemon-like image appears.

  The carrier for developing an electrostatic charge image, the developer for the electrostatic charge image, and the image forming method using them are preferably used particularly for a method for visualizing image information through an electrostatic latent image such as electrophotography. it can.

It is a figure which shows an example of the shape of the electrostatic image developing carrier of this Embodiment. It is a figure which shows the color reproduction range measurement result of the developer in the present Example 9. It is a figure which shows the color reproduction range measurement result of the developer in this comparative example 6. It is a figure which shows the color gamut measurement result of the developer in this Example 10. It is a figure which shows the color reproduction range measurement result of the developer in this Example 11. It is a figure which shows the color reproduction range measurement result of the developer in this Example 12.

Explanation of symbols

  10 core material, 12 virtual inner sphere, 14 virtual outer sphere, 20 protrusion, 22 double-headed arrow.

Claims (8)

A carrier whose core material is coated with a coating resin layer,
The core material has a sphericity represented by formula (I) of 1.220 or less, a surface roughness represented by formula (II) of 1.8 or more and 6.0 or less,
The coating resin layer contains acicular conductive powder,
A carrier for developing an electrostatic charge image, wherein the carrier coated with the core material with the coating resin layer has a surface roughness of 1.6 or less.
Sphericality = (L / 2) ² · π / S (I)
In formula (I), L: maximum diameter of the particle projection image, S: area of the particle projection image.
Surface roughness = SBET / S ′ (II)
In formula (II), SBET: BET specific surface area of particles, S ′: true spherical equivalent surface area. The electrostatic charge image developing carrier according to claim 1,
A plurality of protrusions are formed on the surface of the core of the carrier,
A virtual inner sphere formed by connecting a radius of a virtual outer sphere formed by connecting vertices of a plurality of protrusions formed on the core material and a base portion of the plurality of protrusions formed on the core material. The carrier for developing an electrostatic charge image is characterized in that the difference from the radius is 0.5 to 5 μm. An electrostatic charge image developer containing a toner and a carrier,
An electrostatic image developer, wherein the carrier is the electrostatic image developing carrier according to claim 1. The electrostatic charge image developer according to claim 3.
The toner is prepared by an emulsion polymerization aggregation method and has a shape factor SF1 of 135 or less,
An electrostatic charge image developer prepared by mixing with the carrier. The electrostatic charge image developer according to claim 3.
The toner is an electrostatic charge image developing toner containing at least resin particles and colorant particles, and is heated to a temperature not higher than the glass transition point of the resin particles in a dispersion obtained by dispersing the resin particles. Forming agglomerated particles and preparing an agglomerated particle dispersion, and adding and mixing a fine particle dispersion in which fine particles are dispersed in the agglomerated particle dispersion to adhere the fine particles to the agglomerated particles. A toner for developing an electrostatic charge image produced by a production method comprising a second step of forming adhering particles and a third step of heating and fusing the adhering particles, and the toner measured by a transmission electron microscope A toner for developing an electrostatic charge image, characterized in that the dispersion state of the colorant particles inside satisfies the following two conditions (i) and (ii).
(I) The number dispersion average particle diameter of the colorant particles is in the range of 40 to 60 nm.
(Ii) 70% by number or more of particles having a number dispersion average particle diameter in the range of 40 to 60 nm and 10% by weight or less of coarse side particles having a number dispersion average particle diameter of 200 nm or more in the entire colorant particles. In the carrier for developing an electrostatic image according to any one of claims 3 to 5,
The electrostatic charge image developer has an electric resistance of 1 × 10 ⁵ to 1 × 10 ⁸ Ω · cm and a charge amount of 15 to 25 μc / g when the measurement electric field is 1 × 10 ⁴ V / cm. A developer for developing electrostatic images. After pre-mixing magnetic materials and pre-baking at high temperature, the particles are pulverized into particles having a volume average particle diameter of 0.5 μm or less, and the particles are granulated by adding a dispersant and a binder to the particles, and the volume dispersion average is processed at high temperature. Creating substantially spherical magnetic particles having a particle diameter of 0.5 to 5 μm and substantially spherical magnetic particles having a volume dispersion average particle diameter of 5 to 100 μm;
The magnetic particles having two different particle sizes are added with a dispersant and a binder, granulated, subjected to high-temperature treatment, classified, and a substantially hemispherical magnetic particle of 0.5 to 5 μm is formed on the surface of the magnetic core material. A method for producing a carrier for developing an electrostatic charge image, wherein a magnetic core material having a volume average particle diameter of 10 to 50 μm having protrusions is used as the core material of the carrier.   A step of forming a latent image on the latent image carrier, a step of developing the latent image using a developer, a step of transferring the developed toner image to a transfer member, and heat fixing the toner image on the transfer member An image forming method comprising: using the electrostatic latent image developer according to any one of claims 3 to 6 as the developer.

Images