JP2015166809A - Image forming apparatus, image forming method, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus configured to properly adjust toner concentration and to form a high-resolution and high-quality image with stable image density without causing fog or scattering.SOLUTION: An image forming apparatus 100 includes: an electrostatic latent image carrier 20; forming means; and transfer means which develops an electrostatic latent image with developer having developer containing initial carrier and toner, to transfer a toner image. The developing means includes a supply member for supplying supply developer to a developer housing section. The initial carrier and supply carrier are formed of a magnetic core material and a coating layer. The coating layer includes a particulate having a volume average particle diameter of 340-910 nm. When the amount of charges on the initial carrier with respect to the toner is A(μC/g), the amount of charges on the supply carrier with respect to the toner is B(μC/g), and a mass ratio of the supply carrier in the supply developer is C, the mass ratio C of the supply carrier is 0.05-0.40 and 2.0>(B-A)×C>0.95 is satisfied.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a process cartridge using a two-component developer used for electrophotography, electrostatic recording method and the like.

In a two-component developing device used in an image forming apparatus, a two-component developer containing toner and a carrier contained in the developer containing portion is stirred and frictionally charged, and then a developer carrying carrier Is supplied to the electrostatic latent image carrier and the latent image on the electrostatic latent image carrier is developed. At this time, the toner is consumed and reduced, but the carrier is not consumed. It remains in the (developer container). For this reason, the carrier has a higher agitation frequency in the developer accommodating portion than the toner, and easily deteriorates accordingly. Such deterioration of the carrier makes the charge amount of the toner unstable, for example, and causes a decrease in image quality.
Therefore, in order to suppress the deterioration of the carrier, not only the toner but also the carrier is appropriately replenished to the developer accommodating portion, and the two-component developer that gradually becomes excessive by the carrier replenishment is recovered. As a result, a method of replacing the deteriorated carrier in the developer accommodating portion with a new carrier to be replenished, that is, so-called “trickle development” has been introduced.

On the other hand, in the toner in the two-component developer, the particle size is reduced to improve the quality of the output image, the high temperature offset resistance, the low temperature fixability for energy saving, and the storage and transportation after production. Therefore, heat-resistant storage stability that can withstand high temperature and high humidity is required. In particular, since the power consumption during fixing accounts for a large part of the power consumption in the image forming process, it is very important to improve the low-temperature fixability.
Therefore, for the purpose of obtaining a high level of low-temperature fixability, research on a resin containing a crystalline polyester resin and a toner containing a release agent is underway.

However, although the toner containing these crystalline polyester resins is excellent in low-temperature fixability, it is inferior in the blocking property of the toner image after fixing, and when the printed matter on which the toner image is printed is stored at a high temperature, There is a problem that image fusion and peeling are likely to occur.
Therefore, toner having no adhesion (so-called filming) of toner to the carrier, the photoconductor, and the blade, and having excellent low-temperature fixability, high-temperature offset resistance, heat-resistant storage stability, and blocking resistance of the toner image after fixing. Is required.

  As the carrier in the two-component developer, prevention of toner filming, formation of a uniform surface, prevention of surface oxidation, prevention of decrease in moisture sensitivity, extension of developer life, and surface of the photoreceptor For the purpose of prevention of adhesion, protection of the photoreceptor from scratches or wear, control of the charge polarity, adjustment of the charge amount, a resin having a low surface energy such as a fluororesin or a silicone resin is applied to the surface of the carrier core material. Research on carriers that have achieved a long life by coating is underway.

However, in recent years, there has been a tendency to further promote low-temperature fixing of toner to reduce power consumption, and it has been used for commercial printing, and in combination with higher printing speed, the toner spent on the carrier and the carrier coating film have been scraped off. The carrier deterioration due to is more likely to occur.
Therefore, there is a need for a carrier that can meet the demand for higher speed image formation.

  The recent increase in printing speed is a factor that causes a problem of toner deterioration. In particular, toner containing crystalline polyester tends to deteriorate due to friction with a carrier and the like, and the amount of charge (Q / M) tends to decrease as the number of printed sheets increases. In addition to this, when the Q / M decrease due to the above-described carrier deterioration occurs, a problem arises that the Q / M decrease becomes large when the number of printed sheets is increased as a developer.

In response to this problem, there is a movement to cope with fluctuations in developing ability due to a Q / M reduction by an excellent process control technique. However, the Q / M reduction has another problem that the bulk density of the developer greatly fluctuates. When the bulk density fluctuation of the developer is large, it is used to adjust the toner density necessary for process control. This causes a problem that the detection error of the toner density sensor is increased. The toner density is an indispensable element for adjusting the developing ability in process control. If this adjustment mechanism goes wrong, the entire process control will not function sufficiently, and background fogging, toner scattering, toner density due to excessive toner density Problems such as insufficient development capability (decrease in ID) due to the decrease occur.
Therefore, it is desired to construct an image forming process that is not affected by the Q / M reduction of the developer.

In order to solve the above problems, various reports have been made in image formation using trickle development.
For example, in order to keep the charging property stable and obtain a stable image over a long period of time, in a carrier in which a coating layer is formed on a core material, a carrier in which specific conductive fine particles are contained in the coating layer, or a coating layer with a specific resin A developing method using the formed carrier is disclosed (for example, see Patent Documents 1 and 2).
In addition, for example, a developing method is disclosed that specifies that the charge amount of the carrier in the replenishing cartridge is larger than the carrier in the developer container in order to obtain stable image quality over a long period of time (see, for example, Patent Documents 3 and 4). ).

  However, in order to meet the recent demand for further low-temperature fixing and high-speed image formation, it is possible to accurately adjust the toner density, to achieve a stable image density over a long period of time, and to prevent background fogging and toner scattering. However, these disclosed methods are still not satisfactory and there is room for improvement.

  An object of the present invention is to solve the above-described problems and achieve the following objects. In other words, the present invention can accurately adjust the toner density in response to the demands for low-temperature fixing and high-speed image formation, and can stably achieve a sufficient image density over a long period of time without causing background fog or toner scattering. An object of the present invention is to provide an image forming apparatus capable of forming a fine and high quality image.

Means for solving the problems are as follows. That is, the image forming apparatus of the present invention includes an electrostatic latent image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image carrier. The electrostatic latent image formed on the toner is developed using the developer contained in a developer containing portion having a carrier containing at least an initial carrier and a developer containing toner, thereby forming a toner image. An image forming apparatus comprising: a transfer unit configured to transfer the toner image formed on the electrostatic latent image carrier to a recording medium;
The developing means includes a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount A (μC / g) of the initial carrier with respect to the toner is set to B (μC / g), and the charge amount of the supply carrier with respect to the toner is set to B (μC / g). When the mass ratio is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95.

  According to the present invention, the above-described problems can be solved and the object can be achieved, and the toner density can be accurately adjusted to meet the demands for low-temperature fixing and high-speed image formation. It is possible to provide an image forming apparatus that can be stably realized over a long period of time and can form a high-definition and high-quality image without causing background fog or toner scattering.

FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating an example of the process cartridge of the present invention. FIG. 3 is a view for explaining a cell for measuring the volume resistivity of the electrostatic latent image developing carrier in the present invention.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, and a transfer unit, and further includes other units such as a fixing unit and a cleaning unit as necessary. Means, static elimination means, recycling means, control means, and the like.
The image forming method of the present invention includes an electrostatic latent image forming step, a developing step, and a transfer step, and further, if necessary, other steps such as a fixing step, a cleaning step, a static elimination step, a recycling step, Including control processes.
The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing The transfer step can be performed by the transfer unit, and the other steps can be performed by the other units.

<Electrostatic latent image carrier>
The electrostatic latent image carrier is not particularly limited as long as an electrostatic latent image is formed by the electrostatic latent image forming unit, and can be appropriately selected according to the purpose. And a photosensitive layer, and a surface protective layer, and further include other layers as necessary.
The layer structure of the electrostatic latent image carrier is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a support and a photosensitive layer (charge generation layer) having at least a laminated structure on the support , A charge transport layer), and a surface protective layer in this order, and may have an undercoat layer as necessary, and includes a configuration in which the surface protective layer comes to the outermost surface. In addition, a mode in which a photosensitive layer having a single layer structure mainly composed of a charge generating substance and a charge transporting substance on a support and a surface protective layer on the photosensitive layer may be used.

<Electrostatic latent image forming means and electrostatic latent image forming step>
The electrostatic latent image forming means is not particularly limited as long as it is a means for forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected according to the purpose. And means for forming an electrostatic latent image by combining the means and the exposure means.
The electrostatic latent image forming step is not particularly limited as long as it is a step of forming an electrostatic latent image on the electrostatic latent image carrier, and can be appropriately selected according to the purpose. A step of forming an electrostatic latent image by combining the step and the exposure step may be mentioned.
The charging means is not particularly limited as long as it is a means for charging the surface of the electrostatic latent image carrier, and can be appropriately selected according to the purpose. There is a means for applying a voltage to the surface of the latent image carrier.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charger provided with a conductive or semiconductive roller, brush, film, rubber blade, or the like. And non-contact chargers utilizing corona discharge such as corotron and scorotron.
The exposure unit is not particularly limited as long as it is a unit that exposes the surface of the electrostatic latent image carrier charged by the charging unit like an image to be formed, and is appropriately selected according to the purpose. Examples of the exposure apparatus include a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system.

<Developing means and development process>
The developing means accommodates the electrostatic latent image formed on the electrostatic latent image carrier in a developer accommodating portion having a carrier including at least an initial carrier and a developer including toner. It is a means for developing with an agent to form a toner image.
In the developing step, the electrostatic latent image formed on the electrostatic latent image carrier is stored in a developer container, and includes a carrier including at least an initial carrier and a developer including toner. This is a step of developing and forming a toner image.
The developing means has a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier.
The developing step includes a replenishment process for replenishing the developer accommodating portion with a replenishment developer including at least a replenishment carrier from a replenishment cartridge.
The developing means is not particularly limited as long as it is a means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer containing toner to form a toner image. The toner image can be selected using, for example, a developing device that has the function of containing the developer and imparting the developer to the electrostatic latent image in a contact or non-contact manner. Preferably formed.

The developing means of the present invention has a developer accommodating portion that accommodates a developer containing a carrier and toner.
The developing means may be of a dry development type or a wet development type, and may be a single color development means or a multicolor development means.

The developing means preferably includes a stirrer for stirring and charging the toner and the carrier in the developer accommodating portion, and a rotatable magnet roller.
In the developer accommodating portion, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. Since the magnet roller is disposed in the vicinity of the electrostatic latent image carrier, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrostatically attracted by the static force. It moves to the surface of the electrostatic latent image carrier. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrostatic latent image carrier.

  Further, the developing means of the present invention has a replenishment cartridge that accommodates a replenishment developer, and a replenishment member that replenishes the developer accommodating portion with the replenishment developer in the replenishment cartridge. Have.

  The developing means of the present invention preferably has a recovery member for recovering excess developer in the developer accommodating portion. By appropriately replenishing not only the toner but also the carrier to the developer accommodating portion, the toner that is reduced due to consumption can be replenished, and at the same time, the deteriorated carrier can be replaced with a new carrier. This is because an excessive developer is present, and the unnecessary developer is recovered.

<< Supply Member >>
The replenishing member is not particularly limited as long as it replenishes the developer accommodating portion with the replenishing developer in the replenishing cartridge, and is selected according to the purpose.

<< Developer >>
The developer is a two-component developer containing a carrier and a toner.
In the present invention, the developer includes both the replenishment developer and the initial developer accommodated in the developer accommodating portion before replenishment.
In the present invention, the carrier means a developing carrier, and is included in the replenishment carrier (hereinafter also referred to as “second carrier”) included in the replenishment developer and the initial developer. Any of the initial carriers (hereinafter also referred to as “first carrier”) is included.
In the present invention, the replenishment developer and the initial developer have different toner and carrier mixing ratios and carrier types.

The replenishment carrier and the initial carrier have the following properties.
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95.

  The replenishment carrier and the initial carrier are selected so that the values of A, B, and C are as described above, and both are combined with toner to provide a replenishment developer and an initial developer. As a result, it was found that good results were obtained and the problems of the present invention could be solved.

  In order to suppress an increase in the bulk density when the number of printed sheets increases, it is necessary to replenish the replenisher carrier at a certain level, but at this time, the ratio C of the replenishment carrier (relative to the total mass of the replenishment developer) (The ratio of the replenishment carrier mass) is less than 0.05, the amount of replenished carrier is small, so that the Q / M drop and the bulk density rise cannot be sufficiently suppressed. When the carrier ratio C exceeds 0.40, the carrier ratio in the developer for replenishment becomes extremely high, and the carrier ratio in the two-component developer that is temporarily replenished becomes 100%. A state where toner is not replenished occurs. For this reason, the toner density temporarily decreases temporarily, and the image density cannot be sufficiently obtained.

Further, as described above, when the Q / M of the developer gradually decreases with the number of printed sheets, setting the charge amount of the replenishment carrier higher than that of the initial carrier can reduce the Q / M and increase the bulk density. It is effective to suppress. However, if the charge amount of the replenishment carrier is set too higher than the charge amount of the initial carrier, the Q / M will increase and the bulk density will decrease. To do. As a result, there is a problem that the toner is not sufficiently supplied, the toner density is lowered, and a sufficient image density cannot be obtained. A similar situation occurs when the ratio of replenishment carriers is increased. As a result of intensive studies by the present inventors with respect to these problems, it has been found that it is important to satisfy the above condition in order to solve the problems of the present invention.
The values of the charge amounts A (μC / g) and B (μC / g) can be obtained as follows.

[Measurement of charge amounts A and B]
The charge amount (A, B) of the carrier can be measured by a V blow-off device single mode method.
A 6 g initial sample of toner and carrier is prepared with a toner concentration (toner mass / (toner mass + carrier mass)) of 7 mass%. This initial sample is allowed to stand for 2 hours at a temperature of 23 ° C. and a relative humidity of 55%, and is stirred and mixed for 90 seconds with a mag roll having a rotation speed of 285 rpm. The charge amount of the carrier in the measurement sample of 1 g is measured by a V blow-off device (manufactured by Ricoh Creative Development Co., Ltd.) single mode method. At the time of blowing, 795 mesh (aperture 0.016 mm, mesh number (inch) 795) is used. The measurement conditions of the single mode method are height 5 mm, suction 100, and double blow. Note that RICOH Pro C901 cyan toner is used as the blank toner. The details of other measurement conditions conform to the conditions described in Japanese Patent No. 3487464.

The blending ratio of the toner and the replenishment carrier in the replenishment developer accommodated in the replenishment cartridge is preferably 2 to 50 parts by mass of toner with respect to 1 part by mass of the carrier. When the amount of toner is less than 2 parts by mass, the amount of replenishment carrier is excessive, the carrier supply is excessive, and the carrier concentration in the developing device becomes too high. And the toner is dissolved by heat, and toner spent tends to occur. Further, when the developer charge amount increases, the developing ability decreases and the image density decreases. On the other hand, when the amount exceeds 50 parts by mass, the carrier ratio in the replenishment developer decreases, so that the replacement of carriers in the image forming apparatus decreases, and the effect on carrier degradation that was originally intended cannot be expected.
The mixing ratio of the toner and the initial carrier in the initial developer stored in the developer storage unit is preferably 0.05 part by mass to 0.1 part by mass with respect to 1 part by mass of the carrier.

  In the present invention, it is preferable to use the carrier described below in order to adjust the A value, the B value, and the C value to desired values and to have a relationship defined in the present invention.

<<< Career >>>>
In the present invention, the carrier includes both a replenishment carrier and an initial carrier.
The carrier includes magnetic core particles and a coating layer that covers the surface of the core particles, and further includes other components as necessary.
In the present invention, as will be described later, fine particles are contained in the coating layer of the carrier, and by using fine particles having a volume average particle size of the fine particles in a specific range, the charge amount A of the initial carrier, and the The charge amount B of the replenishment carrier is effectively adjusted.

  In the present invention, the volume average particle diameter of the carrier is preferably 20 μm or more and 45 μm or less. When the volume average particle diameter of the carrier is less than 20 μm, the magnetization per particle is weakened, so that carrier adhesion may occur. When the thickness exceeds 45 μm, the impact force when the carriers collide with each other increases, and the stress on the convex portion of the carrier surface layer increases, so that the convex portion of the carrier surface layer is sufficient due to the embedding of the fine particles or scraping of the fine particles. The charging ability of the developer cannot be kept constant during toner spending.

[Measurement of volume average particle diameter of carrier]
The volume average particle diameter of the carrier can be measured using an SRA type of a Microtrac particle size analyzer (manufactured by Nikkiso Co., Ltd.). What was performed by the range setting of 0.7 micrometer or more and 125 micrometers or less is used. Further, methanol is used for the dispersion, and the refractive index is set to 1.33, and the refractive indexes of the carrier and the core material are set to 2.42.

The volume resistivity of the carrier is preferably 8 (Log Ω · cm) to 14 (Log Ω · cm). If the volume resistivity is less than 8 (Log Ω · cm), carrier adhesion may occur in the non-image area, and if it exceeds 14 (Log Ω · cm), the edge effect may be at an unacceptable level. is there.
Under actual usage conditions, factors other than volume specific resistance such as toner concentration, magnetization characteristics of core material particles, and usage environment are also involved. Considering this, the volume resistivity is more preferably 9.5 (Log Ω · cm) to 12.1 (Log Ω · cm).

  The volume resistivity can be measured using the cell shown in FIG. Specifically, first, a carrier (3) is placed in a cell composed of a fluororesin container (2) in which an electrode (1a) and an electrode (1b) having a surface area of 2.5 cm × 4 cm are accommodated at a distance of 0.16 cm. ) And is tapped 10 times with a drop height of 1 cm and a tapping speed of 30 times / minute. Next, a DC voltage of 1,000 V is applied between the electrodes (1a) and (1b), and the resistance value r [Ω] after 30 seconds is used with a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Company). The volume resistivity (Ω · cm) can be calculated from the following formula 1.

    r × (2.5 × 4) /0.16 Formula 1

-Core particles-
The core particle is not particularly limited as long as it is a magnetic material, and can be appropriately selected according to the purpose. Examples thereof include resin particles in which magnetic materials such as various alloys and compounds are dispersed in a resin. Among these, Mn type ferrite, Mn—Mg type ferrite, Mn—Mg—Sr ferrite and the like are preferable from the viewpoint of environmental considerations.

-Coating layer-
The coating layer covers the surface of the core material and includes a resin and fine particles.
In the present invention, the volume average particle diameter of the fine particles is 340 nm to 910 nm.

--Fine particles--
In the present invention, it is extremely important that the volume average particle size of the fine particles contained in the coating layer is 340 nm or more and 910 nm or less.
When the fine particles are contained in the coating layer, irregularities due to the fine particles appear on the surface of the coating layer. The height of the irregularities is determined by the size of the fine particles. The larger the fine particles, the larger the irregularities on the surface. As described above, in recent years, toner is easily deformed and melted by stress due to friction with the carrier due to low-temperature fixing, and toner spent on the carrier is likely to occur. As the toner spent on the carrier advances, the exposed area of the carrier surface layer decreases and the ability to charge the toner decreases. As a result, since the Q / M of the entire developer is decreased, the bulk density of the developer is increased. When the bulk density rises, the toner density sensor makes a false detection that the toner density is lowered, and the toner is replenished excessively. As a result, the toner density rises more than necessary, causing problems such as background fogging and toner scattering. However, by providing unevenness on the carrier surface layer, the toner spent tends to adhere to the concave portion of the carrier surface layer, and the convex portion becomes difficult to toner spent due to friction between carriers. For this reason, when the height of the convex portion is sufficient, an exposed portion of the carrier surface layer can be ensured even if toner spent occurs, so that the Q / M drop and the bulk density rise of the developer can be minimized.

In the present invention, if the volume average particle size of the fine particles is less than 340 nm, the surface of the carrier layer is not sufficiently uneven, and the entire carrier surface layer is covered with the toner spent, resulting in a decrease in Q / M and an increase in bulk density of the developer. Can not be suppressed sufficiently. Further, when the volume average particle diameter exceeds 910 nm, the average particle diameter of the fine particles becomes too large with respect to the average particle diameter of the carrier, so that the fine particles are easily separated from the carrier, and the carrier due to a decrease in carrier resistance or the like. Problems such as adhesion are likely to occur.
The volume average particle diameter of the fine particles can be determined as follows.

[Measurement of volume average particle diameter of fine particles]
The volume average particle size of the fine particles can be measured with an automatic particle size distribution analyzer CAPA-700 (manufactured by Horiba Seisakusho). As a pretreatment for measurement, 300 mL of a toluene solution is added to 30 mL of aminosilane (SH6020: manufactured by Toray Dow Corning Silicone) in a juicer mixer. Add 6.0 g of sample, set mixer rotation speed to (low), and disperse for 3 minutes. An appropriate amount of the dispersion is added to 500 mL of a toluene solution prepared in advance in a 1,000 mL beaker and diluted. The diluting solution is continuously stirred with a homogenizer. This diluted solution is measured with an ultracentrifugal automatic particle size distribution analyzer CAPA-700.
-Measurement conditions-
Rotation speed: 2000rpm
Maximum particle size: 2.0 μm
Minimum particle size: 0.1 μm
Particle size interval: 0.1 μm
Dispersion medium viscosity: 0.59 mPa · s
Dispersion medium density: 0.87 g / cm ³
Particle density: For the density of fine particles, the true specific gravity value measured using a dry automatic bulk density meter Accupic 1330 (manufactured by Shimadzu Corporation) is input.

  The content ratio a of the fine particles in the coating layer may be 50% by mass or more and 70% by mass or less. When the content of the fine particles is less than 50% by mass, it is difficult to keep the charging ability of the carrier constant during toner spent because the area of the convex portion of the carrier surface layer is not sufficient. In addition, when the content of the fine particles exceeds 70% by mass, the fine particles in the coating layer are too much, so that the fine particles are easily peeled off, and as a result, the core material is exposed to cause carrier adhesion and the like. A problem will occur.

  In the present invention, the ratio (D / h) of the volume average particle diameter D (nm) of the fine particles to the film thickness h (nm) of the coating layer is 1.5 <(D / h) <2.0. It is good to be. As described above, when the fine particles are contained in the coating layer, irregularities due to the fine particles appear on the surface of the coating layer. The size of the unevenness is determined by the fine particle diameter. On the other hand, when the coating layer is thick, the amount of the fine particles embedded in the coating film increases, and the unevenness of the carrier surface layer is not sufficient. When D / h is 1.5 or less, the fine particles buried in the coating layer of the carrier increase, and thus the effect of suppressing the Q / M reduction and the bulk density increase due to the unevenness of the carrier surface layer cannot be obtained sufficiently. When D / h is 2.0 or more, it is difficult to sufficiently fix the fine particles in the carrier coating layer, and many of the fine particles are detached from the coating layer of the carrier. As a result, the core material is exposed, causing problems such as carrier adhesion.

In the present invention, it is desirable to use conductive fine particles as the fine particles.
The conductive fine particles are not particularly limited, but it is suitable to cover a certain amount of the base particles with a conductive layer such as tin oxide or ITO.
Examples of the white inorganic pigment used as the base particles of the conductive fine particles include commercially available titanium dioxide, aluminum oxide, silicon dioxide, zinc oxide, barium sulfate, zirconium oxide, alkali metal titanate, and muscovite. In more detail, taking titanium dioxide as an example, the size of the particles is not limited, and even in shapes such as spheres and needles, anatase type, rutile type and amorphous Can also be used.
Among the above examples, aluminum oxide is more preferable as the base particle of the conductive fine particles. Compared with other white inorganic pigments, aluminum oxide can supply a charge that is not excessive or insufficient, and a high image area ratio print density on a low speed machine due to an increase in charge at a low image area ratio print density on a high speed machine. Optimum charging can be obtained in a wide range up to the time of charge reduction.

  The conductive fine particles in the present invention can be produced by various methods. For example, a tin salt hydrate layer containing a hydrate of phosphorus or tungsten salt is uniformly formed on the surface of base particles (white inorganic pigment particles). It can manufacture by making it deposit and baking the obtained coating layer.

In order to uniformly deposit a tin salt hydrate layer containing a hydrate of phosphorus or tungsten salt on the surface of the substrate, for example, a phosphorus salt (for example, phosphorus pentoxide, POCl ₃ or the like) or a tungsten salt (for example, chloride) Tungsten, tungsten oxychloride, sodium tungstate, tungstate, etc., and tin compounds (for example, tin salts such as tin chloride, tin sulfate, tin nitrate, etc.), stannates such as sodium stannate, potassium stannate, tin, etc. PH adjusting agent for depositing and depositing acidic aqueous liquids containing organic tin compounds such as alkoxides on the surface of the base particles in the form of hydrates with respect to the dropped phosphorus or tungsten and tin (For example, an aqueous base solution) and simultaneously dropping the base particles into an aqueous solution in which the base particles are dispersed, It can be carried out while preventing dissolution and surface alteration. At this time, the doping ratio of phosphorus or tungsten to SiO ₂ can be adjusted by adjusting the dropping amount of phosphorus or tungsten and the dropping amount of tin chloride solution. However, the isoelectric point of tin hydrate, that is, tin hydroxide or stannic acid, and the isoelectric point of phosphorus or Wangsten component are not necessarily the same, and their solubility at a specific pH is not necessarily different. Also note that.

  In addition, for example, methanol, methyl ethyl ketone, etc., for the purpose of alleviating the aggressiveness to the substrate during the dropping operation and the extreme hydration reaction of phosphorus, tungsten, and tin, and homogenizing the coating layer covering the substrate particles These water-soluble organic solvents can be mixed and used. The obtained hydrate is preferably fired at 300 ° C. to 850 ° C. in a non-oxidizing atmosphere. Thereby, compared with what heat-processed in the air, the volume specific resistance of electroconductive fine particles can be suppressed very low.

  The powder specific resistance of the conductive fine particles is preferably 2 (Ωcm) to 15 (Ωcm). When the carrier is formed, the prescription amount of the conductive fine particles is determined with the aim of the resistance value. However, when the powder specific resistance is 2 (Ωcm) or less, the prescription amount decreases and the strength of the carrier film decreases. And it becomes fragile. On the other hand, when the powder specific resistance is 15 (Ωcm) or more, the amount of the prescription increases, so that there are too many conductive fine particles in the resin layer, so that the conductive fine particles are easily peeled off. The powder specific resistance of the conductive fine particles can be measured using, for example, an LCR meter (manufactured by Yokogawa Hewlett Packard).

--Resin--
The resin is not particularly limited as long as a resin layer covering the core particle surface can be formed, and can be appropriately selected according to the purpose. For example, the A portion represented by the following general formula (A) (and An acrylic copolymer obtained by radical copolymerization, including a monomer A component for the purpose; the same shall apply hereinafter) and a B portion represented by the following general formula (B) (and a monomer B component for the same; hereinafter the same). Resin obtained by heat-processing after coat | covering is mentioned.

Part A (and monomer A component for it):
Where
R ¹ : Any one of a hydrogen atom and a methyl group m: an integer of 1 to 8 R ² : an alkyl group having 1 to 4 carbon atoms, a methyl group, an ethyl group, a propyl group, and a butyl group A part (and monomer) In A component), X = 10 mol% to 90 mol% is preferable, 10 mol% to 40 mol% is more preferable, and 20 mol% to 30 mol% is particularly preferable.

  The A portion (monomer A component) has, for example, an atomic group having a large number of methyl groups in the side chain, tris (trimethylsiloxy) silane, and the ratio of the A portion (monomer A component) to the entire resin is When it is higher, the surface energy is reduced, and adhesion of the resin component, wax component, etc. of the toner is reduced. If the A portion (monomer A component) is less than 10 mol%, a sufficient effect cannot be obtained, and adhesion of the toner component increases rapidly. Moreover, when it exceeds 90 mol%, while B part (monomer B component) and toughness are insufficient, the adhesiveness of a core material and a resin layer falls, and durability of a carrier film worsens.

Examples of the monomer A component that generates such an A moiety include a tris (trialkylsiloxy) silane compound represented by the following formula.
In the following formulae, Me represents a methyl group, Et represents an ethyl group, and Pr represents a propyl group.
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiPr 3) 3
The production method of the monomer component A for the A portion is not particularly limited, but a method of reacting tris (trialkylsiloxy) silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst, or JP-A-11-217389. It can be obtained by a method of reacting methacryloxyalkyltrialkoxysilane and hexaalkyldisiloxane in the presence of a carboxylic acid and an acid catalyst.

B part (and monomer B component / precursor monomer B): (crosslinking component)
Where
R ¹ : any one of hydrogen atom and methyl group m: integer of 1 to 8 R ² : alkyl group having 1 to 4 carbon atoms, methyl group, ethyl group, propyl group, and butyl group R ³ : carbon number 1-8 alkyl groups (methyl group, ethyl group, propyl group, butyl group, etc.) or C1-C4 alkoxy groups (methoxy group, ethoxy group, propoxy group, butoxy group).
That is, the monomer B component (including the precursor) for the B portion is a radically polymerizable bifunctional (when R ³ is an alkyl group) or a trifunctional (when R ³ is also an alkoxy group) silane compound Y = 10 mol% to 90 mol% is preferable, 10 mol% to 80 mol% is more preferable, and 15 mol% to 70 mol% is particularly preferable.
If the B component is less than 10 mol%, sufficient toughness cannot be obtained. On the other hand, when it exceeds 90 mol%, the coating becomes hard and brittle, and film scraping tends to occur. Moreover, environmental characteristics deteriorate. It is also conceivable that a large number of hydrolyzed crosslinking components remain as silanol groups, deteriorating environmental characteristics (humidity dependency).

  Examples of the monomer B component include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, and 3-methacryloxypropyl. Examples include methyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri (isopropoxy) silane, and 3-acryloxypropyltri (isopropoxy) silane.

For example, Japanese Patent No. 3691115 discloses a technique for making the coating layer highly durable using a crosslinked resin.
In Japanese Patent No. 3691115, at least one functional group selected from the group consisting of an organopolysiloxane having a vinyl group at least at a terminal, a hydroxyl group, an amino group, an amide group, and an imide group is provided on the surface of a magnetic particle. Although a carrier for developing an electrostatic image in which a copolymer with a radical copolymerizable monomer is coated with a thermosetting resin crosslinked with an isocyanate-based compound is described, it is sufficient for peeling and scraping of the film. The current situation is that durability is not obtained. The reason is not sufficiently clear, but in the case of a thermosetting resin obtained by crosslinking the above copolymer with an isocyanate compound, the isocyanate in the copolymer resin is understood from the structural formula. There are few functional groups (active hydrogen-containing groups such as amino group, hydroxy group, carboxy group, mercapto group, etc.) per unit weight that react (crosslink) with the compound, and two-dimensional or three-dimensional dense crosslinking at the crosslinking point The structure cannot be formed, and therefore, when used for a long time, the film is easily peeled off or scraped off (the abrasion resistance of the film is small), and it is assumed that sufficient durability is not obtained.
When the film is peeled off or scraped off, the image quality changes due to a decrease in carrier resistance and carrier adhesion occurs. Also, peeling or scraping of the coating reduces the fluidity of the developer and causes a decrease in the amount of pumping, which causes a decrease in image density, contamination when toner is increased, and toner scattering.

The present invention is a copolymer resin having a large number of bifunctional or trifunctional crosslinkable functional groups (points) (2 to 3 times more per weight) than the resin unit weight. Further, since it is cross-linked by condensation polymerization, it is considered that the coating is extremely tough and difficult to scrape, and high durability is achieved.
Further, it is presumed that the aging stability of the coating is maintained since the crosslinking by the siloxane bond of the present invention has a larger binding energy and is more stable against heat stress than the crosslinking by the isocyanate compound.
In the present invention, in order to provide sufficient flexibility and to improve the adhesion between the core material particles and the resin layer, and between the resin layer and the conductive fine particles, the following general C component represented by Formula (C) can be included.

C part (and monomer C component): (acrylic component)

Where
R ¹ : any one of a hydrogen atom and a methyl group R ² : an aliphatic hydrocarbon group having 1 to 4 carbon atoms, an acryloyl group or a methacryloyl group which is a methyl group, an ethyl group, a propyl group, and a butyl group It is a radically polymerizable acrylic compound having
The contents of the component A and the component B when the component C is included are X = 10 mol% to 40 mol%, Y = 10 mol% to 40 mol%, and the content of the C component is Z = 30 mol% to 80 mol% is preferable, and 35 mol% to 75 mol% is more preferable. And 60 mol% <Y + Z <90 mol% is preferable, and 70 mol% <Y + Z <85 mol% is more preferable.
If the C part (monomer C component) is greater than 80 mol%, either X or Y will be 10 or less, making it difficult to achieve both water repellency, hardness and flexibility (film scraping) of the carrier film. Become.

  As the acrylic compound (monomer) of the monomer C component for the C portion, acrylic acid ester and methacrylic acid ester are preferable. Specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate 2- (dimethylamino) ethyl methacrylate, 2- (dimethylamino) ethyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (dimethylamino) propyl acrylate, 2- (diethylamino) ethyl methacrylate, 2- (diethylamino) Examples include ethyl acrylate. Among these, alkyl methacrylate is preferable, and methyl methacrylate is more preferable. Moreover, these compounds may be used individually by 1 type, and may use 2 or more types of mixtures.

The above copolymer resin is an acrylic copolymer obtained by radical copolymerization of each monomer including the A component and the B component, and has many crosslinkable functional groups per unit weight of the resin. In addition, since the crosslinking component B is subjected to polycondensation by crosslinking by heat treatment, it is considered that the resin layer is extremely tough and difficult to scrape, and high durability is achieved.
In addition, it is surmised that the cross-linking by the siloxane bond in the present invention has higher binding energy and is more stable against heat stress than the cross-linking by the isocyanate compound, so that the stability of the resin layer with time is maintained. .

The resin preferably contains a silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis.
A silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis (eg, a negative group such as an alkoxy group or a halogeno group bonded to a Si atom) is a copolymer of the above-mentioned copolymer The crosslinking component B can be subjected to condensation polymerization directly or with the crosslinking component B in a state of being converted to a silanol group. The toner spent property is further improved by adding a silicone resin component to the copolymer.
In the present invention, a silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis used in forming the resin layer is represented by the following general formula (I). It preferably contains at least one of the repeating units shown.

Here, in the formula (I), A ¹ is a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, a lower alkyl group having 1 to 4 carbon atoms, or an aryl group (such as a phenyl group or a tolyl group). ² is an alkylene group having 1 to 4 carbon atoms or an arylene group (such as a phenylene group).
In the aryl group of the above formula, the carbon number thereof is preferably 6-20, and more preferably 6-14. This aryl group includes an aryl group derived from benzene (phenyl group), an aryl group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene, and anthracene, and a chain polycyclic such as biphenyl and terphenyl. An aryl group derived from an aromatic hydrocarbon is included. The aryl group may be substituted with various substituents.
6-20 are preferable and, as for carbon number of an arylene group, 6-14 are more preferable. As this arylene group, in addition to an arylene group derived from benzene (phenylene group), an arylene group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene and anthracene, and a chain polycyclic such as biphenyl and terphenyl An arylene group derived from an aromatic hydrocarbon is included. The arylene group may be substituted with various substituents.

Although it does not specifically limit as a commercial item of the silicone resin which can be used for this invention, KR251, KR271, KR272, KR282, KR252, KR255, KR152, KR155, KR211, KR216, KR213 (above, Shin-Etsu Silicone company make), AY42- 170, SR2510, SR2400, SR2406, SR2410, SR2405, SR2411 (manufactured by Toray Dow Corning) (manufactured by Toray Silicone).
As described above, various silicone resins can be used. Among them, methyl silicone resin is particularly preferable because of low toner spent property and small environmental fluctuation of charge amount.

As a weight average molecular weight of a silicone resin, 1,000-100,000 are preferable and 1,000-30,000 are more preferable. When the molecular weight of the resin to be used is larger than 100,000, the viscosity of the coating solution increases excessively at the time of coating, and the coating film uniformity may not be sufficiently obtained, or the density of the resin layer may not be sufficiently increased after curing. If it is less than 1,000, problems such as brittleness of the cured resin layer tend to occur.
As a content rate of a silicone resin, 5 mass%-95 mass% are preferable with respect to the said copolymer, and 10 mass%-60 mass% are more preferable. When the amount is less than 5% by mass, an improvement effect such as spent property cannot be obtained. When the amount is more than 95% by mass, the toughness of the resin layer is insufficient and the film is easily scraped.

  In addition, the resin may contain a resin other than the silicone resin having the silanol group and / or the hydrolyzable functional group. Such a resin is not particularly limited, but an acrylic resin, an amino resin, Polyvinyl resin, polystyrene resin, halogenated olefin resin, polyester, polycarbonate, polyethylene, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymer of vinylidene fluoride and vinyl fluoride, tetra Examples include fluoroterpolymers such as terpolymers of fluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins having no silanol groups or hydrolyzable functional groups, and two or more of them may be used in combination. Among them, an acrylic resin is preferable because it has high adhesion to the core material particles and conductive fine particles and low brittleness.

  The acrylic resin preferably has a glass transition point of 20 ° C to 100 ° C, more preferably 25 ° C to 80 ° C. Since such an acrylic resin has an appropriate elasticity, when the developer is triboelectrically charged, a shock is applied to the resin layer due to the friction between the toner and the carrier or the friction between the carriers. It can be absorbed and deterioration of the resin layer and the conductive fine particles can be prevented.

The resin further preferably contains a cross-linked product of an acrylic resin and an amino resin. Thereby, fusion | melting of resin layers can be suppressed, maintaining moderate elasticity. The amino resin is not particularly limited, but a melamine resin and a benzoguanamine resin are preferable because the charge imparting ability of the carrier can be improved. In addition, when it is necessary to appropriately control the charge imparting ability of the carrier, another amino resin may be used in combination with the melamine resin and / or the benzoguanamine resin.
As the acrylic resin capable of crosslinking with the amino resin, those having a hydroxyl group and / or a carboxyl group are preferable, and those having a hydroxyl group are more preferable. Thereby, adhesiveness with core material particle | grains or electroconductive fine particles can be improved, and the dispersion stability of electroconductive fine particles can also be improved. In this case, the acrylic resin preferably has a hydroxyl value of 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more.

In order to accelerate the condensation reaction of the crosslinking component B, a titanium-based catalyst, a tin-based catalyst, a zirconium-based catalyst, and an aluminum-based catalyst can be used. Of these various catalysts, titanium alkoxides and titanium chelates are particularly preferred among the titanium-based catalysts that give excellent results.
This is considered to be because the effect of promoting the condensation reaction of the silanol group derived from the crosslinking component B is large and the catalyst is hardly deactivated. Examples of the titanium alkoxide catalyst include titanium diisopropoxy bis (ethyl acetoacetate) represented by the following structural formula II. Examples of the titanium chelate catalyst are represented by the following structural formula III. And titanium diisopropoxybis (triethanolaminate).

  In the present invention, the resin preferably contains an aminosilane coupling agent.

  The aminosilane coupling agent is not particularly limited, but γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, N-β- (N-vinylbenzyl). Aminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, and the like, and two or more of them may be used in combination.

  The addition amount of the aminosilane coupling agent is preferably 3% by mass to 15% by mass with respect to the resin from the viewpoint of charging ability and coating film strength.

The resin layer is composed of a copolymer containing the A component and the B component, a titanium diisopropoxybis (ethyl acetoacetate) catalyst, and a copolymer containing the A component and the B component, if necessary. It can form using the composition for resin layers containing resin of this, an aminosilane coupling agent, and a solvent.
Specifically, it may be formed by condensing silanol groups while coating the core material particles with the resin layer composition, or after coating the core material particles with the resin layer composition, It may be formed by condensation.
The method of condensing silanol groups while coating the core material particles with the resin layer composition is not particularly limited, but the method of coating the core particles with the resin layer composition while applying heat, light, etc. Etc. Further, the method of condensing the silanol group after coating the core material particles with the resin layer composition is not particularly limited, and examples thereof include a method of heating after coating the core material particles with the resin layer composition. .

In general, a resin having a large molecular weight has a very high viscosity, and when applied to a substrate having a small particle size, it is easy to cause aggregation of the particles and non-uniformity of the resin layer, and it is extremely difficult to produce a coated carrier.
Therefore, the copolymer resin of the present invention preferably has a weight average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000, and 30,000 to 40,000. It is particularly preferred. If it is less than 5,000, the strength of the resin layer will be insufficient, and if it is 100,000, the liquid viscosity will be high and the carrier productivity will be poor.

In the present invention, the coating layer has no film defects, and the average film thickness is preferably 300 nm to 900 nm. If the average film thickness is less than 300 nm, the coating layer is likely to be destroyed due to use, and the film may be scraped. In addition, the resistance adjusting effect described later is not sufficiently exhibited.
The film thickness h (nm) of the coating layer can be measured by the following method.

[Measurement of coating layer thickness]
The method for measuring the thickness h of the resin part in the coating layer is not particularly limited. For example, the thickness of the resin part of the coating layer covering the carrier surface is observed using a transmission electron microscope (TEM). Can be obtained from the average value. Specifically, only the thickness of the resin part existing between the core material surface and the particles is measured. The thickness of the resin part existing between the particles and the thickness of the resin part on the inorganic fine particles are not included in the measurement. The average of arbitrary 50 point measurements of the carrier cross section can be obtained and used as the thickness h (μm).

<<< Toner >>>
The toner includes a binder resin and a colorant, and further includes other components as necessary.
The toner may be a monochrome toner or a color toner.
Further, the toner particles may contain a release agent for application to an oilless system in which toner fixing prevention oil is not applied to the fixing roller. Such toner generally tends to cause filming. However, since the carrier of the present invention described above can suppress filming, the developer of the present invention maintains good quality for a long time. can do.
In addition, color toners, particularly yellow toners, generally have a problem of color stains due to scraping of the carrier coating layer (resin layer). Can be suppressed.

The toner can be produced using a known method such as a pulverization method or a polymerization method. For example, when a toner is manufactured using a pulverization method, first, a melt-kneaded product obtained by kneading a toner material is cooled, pulverized, and classified to prepare base particles. Next, in order to further improve transferability and durability, an external additive is added to the base particles to produce a toner.
At this time, the apparatus for kneading the toner material is not particularly limited and can be appropriately selected depending on the purpose. For example, a batch type two roll, Banbury mixer, KTK type twin screw extruder (Kobe Steel Works) TEM type twin screw extruder (Toshiba Machine Co., Ltd.), twin screw extruder (KCK), PCM type twin screw extruder (Ikegai Iron Works), KEX type twin screw extruder (Kurimoto Iron Works) And a continuous twin-screw extruder such as a co-kneader (manufactured by Buss).

When the cooled melt-kneaded product is pulverized, it is roughly pulverized using a hammer mill, a rotoplex, etc., and then finely pulverized using a fine pulverizer using a jet stream or a mechanical pulverizer. be able to. In addition, it is preferable to grind | pulverize so that an average particle diameter may be 3-15 micrometers.
Furthermore, when classifying the pulverized melt-kneaded material, a wind classifier or the like is used. In addition, it is preferable to classify | categorize so that the average particle diameter of a base particle may be 5 micrometers-20 micrometers.
In addition, when an external additive is added to the base particle, the external additive adheres to the surface of the base particle while being pulverized by mixing and stirring using a mixer.

-Binder resin-
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, styrene and its substituted homopolymers, styrene copolymers, polymethyl methacrylate, polybutyl methacrylate , Polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, phenol resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, aromatic Based petroleum resins. Two or more of these may be used in combination.

  However, in the present invention, it is preferable to contain a crystalline polyester resin as the binder resin. When the toner containing the crystalline polyester resin is used, it is possible to accurately adjust the toner density even for a high-speed machine intended for low-temperature fixing, and a sufficient image density can be stably realized over a long period of time. High-definition and high-quality images can be formed without causing fogging and toner scattering.

Examples of the homopolymer of the styrene and the substituted product thereof include polystyrene, poly p-styrene, and polyvinyl toluene.
Examples of the styrene copolymer include styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer. Polymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene -Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid ester copolymer, etc. .

In particular, the binder resin considering pressure fixing includes, for example, polyolefin, olefin copolymer, epoxy resin, polyester, styrene-butadiene copolymer, polyvinyl pyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid modified A phenol resin, a phenol modified terpene resin, etc. are mentioned.
Examples of the polyolefin include low molecular weight polyethylene and low molecular weight polypropylene.
As the olefin copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, Examples thereof include ethylene-vinyl acetate copolymer and ionomer resin.
Two or more of these resins may be used in combination.

-Colorant-
The colorant (pigment or dye) is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a yellow pigment, an orange pigment, a red pigment, a purple pigment, a blue pigment, a green pigment, and a black pigment. Is mentioned.
Examples of the yellow pigment include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, etc. Can be mentioned.
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK and the like.
Examples of the red pigment include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B and the like. It is done.

Examples of the purple pigment include Fast Violet B and Methyl Violet Lake.
Examples of the blue pigment include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of the green pigment include chrome green, chromium oxide, pigment green B, and malachite green lake.
Examples of the black pigment include azine dyes, metal salt azo dyes, metal oxides, and composite metal oxides. More specifically, carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline. Black.
Two or more of the above pigments may be used in combination.

-Other ingredients-
The toner may contain a release agent, a charge control agent, and an external additive.
The release agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyolefin, fatty acid metal salt, fatty acid ester, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carna Uba wax, ester wax and the like can be mentioned.
Examples of the polyolefin include polyethylene and polypropylene.
Two or more of the release agents may be used in combination.
The charge control agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, nigrosine, an azine dye having an alkyl group having 2 to 16 carbon atoms (see Japanese Examined Patent Publication No. 42-1627) ), Basic dyes, basic dye lake pigments, quaternary ammonium salts, dialkyltin compounds, dialkyltin borate compounds, guanidine derivatives, polyamine resins, metal complexes of monoazo dyes, salicylic acid, metal complexes, sulfonated copper phthalocyanine Examples include pigments, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like.

  Examples of the basic dye include C.I. I. Basic Yellow 2 (C.I. 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (C.I. 45160), C.I. I. Basic Red 9 (C.I. 42500), C.I. I. Basic Violet 1 (C.I. 42535), C.I. I. Basic Violet 3 (C.I. 42555), C.I. I. Basic Violet 10 (C.I. 45170), C.I. I. Basic Violet 14 (C.I. 42510), C.I. I. Basic Blue 1 (C.I. 42025), C.I. I. Basic Blue 3 (C.I. 51005), C.I. I. Basic Blue 5 (C.I. 42140), C.I. I. Basic Blue 7 (C.I. 42595), C.I. I. Basic Blue 9 (C.I. 52015), C.I. I. Basic Blue 24 (C.I. 52030), C.I. I. Basic Blue 25 (C.I. 52025), C.I. I. Basic Blue 26 (C.I. 44045), C.I. I. Basic Green 1 (C.I. 42040), C.I. I. Examples include Basic Green 4 (C.I. 42000).

  Examples of the quaternary ammonium salt include C.I. I. Solvent Black 8 (C.I. 26150), benzoylmethyl hexadecyl ammonium chloride, decyl trimethyl chloride, and the like.

Examples of the dialkyltin compound include a dibutyltin compound and a dioctyltin compound.
Examples of the polyamine resin include a vinyl polymer having an amino group and a condensation polymer having an amino group.

Examples of the metal complex salts of monoazo dyes include metal complex salts of monoazo dyes described in JP-B Nos. 41-20153, 43-27596, 44-6397, and 45-26478. Is mentioned.
Examples of the salicylic acid include salicylic acid described in JP-B-55-42752 and JP-B-59-7385.
Examples of the metal complex include dialkyl salicylic acid, naphthoic acid, and dicarboxylic acid Zn, Al, Co, Cr, and Fe.

  Two or more of the charge control agents may be used in combination. For color toners other than black, it is preferable to use a metal salt of a white salicylic acid derivative.

There is no restriction | limiting in particular as said external additive, According to the objective, it can select suitably, For example, an inorganic particle, a resin particle, etc. are mentioned.
Examples of the inorganic particles include silica, titanium oxide, alumina, silicon carbide, silicon nitride, and boron nitride.
Examples of the resin particles include polymethyl methacrylate particles and polystyrene particles having an average particle size of 0.05 μm to 1 μm obtained by a soap-free emulsion polymerization method.
Two or more external additives may be used in combination.
Among these, metal oxide particles such as silica and titanium oxide whose surfaces are hydrophobized are preferable. In addition, when the hydrophobized silica and hydrophobized titanium oxide are used in combination, the amount of added hydrophobized titanium oxide is higher than the hydrophobized silica. Thus, a toner having excellent charge stability with respect to the toner can be obtained.

<Transfer means and transfer process>
The transfer unit is not particularly limited as long as it is a unit that transfers the toner image formed on the electrostatic latent image carrier to a recording medium, and can be appropriately selected according to the purpose. For example, a method of directly transferring a toner image from the surface of the electrostatic latent image carrier to a recording medium, and using an intermediate transfer member, the toner image is primarily transferred onto the intermediate transfer member, and then the toner image is transferred to the recording medium. There is a secondary transfer method above.
The transfer step is a step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium.
Examples of the transfer device used for the transfer means include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

<Other means and other processes>
The image forming apparatus of the present invention may include a fixing unit, a cleaning unit, a charge eliminating unit, a recycling unit, a control unit, and the like as necessary.
The image forming method of the present invention may include a fixing step, a cleaning step, a charge removal step, a recycling step, a control step, and the like as necessary.

<< Fixing means >>
The fixing unit is not particularly limited as long as it is a unit that fixes the toner image transferred to the recording medium, and can be appropriately selected according to the purpose. For example, a known heating and pressing unit is used. be able to. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressing means is preferably 80 ° C to 200 ° C. In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing unit depending on the purpose.
In the fixing, the toner of each color may be transferred to the recording medium for each color, or may be transferred at once in a state where the toner of each color is laminated.

<Embodiment of Image Forming Apparatus>
An image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, first, the electrostatic latent image carrier 20 is rotationally driven at a predetermined peripheral speed, and the peripheral surface of the electrostatic latent image carrier 20 is set to a positive or negative predetermined potential by the charging device 32. Uniformly charged. Next, the peripheral surface of the electrostatic latent image carrier 20 is exposed by the exposure device 33, and electrostatic latent images are sequentially formed. Further, the electrostatic latent image formed on the peripheral surface of the electrostatic latent image carrier 20 is developed by the developing device 40 using the developer containing the carrier and the toner of the present invention to form a toner image. Next, the toner image formed on the peripheral surface of the electrostatic latent image carrier 20 is synchronized with the rotation of the electrostatic latent image carrier 20, and the electrostatic latent image carrier 20 and the transfer device 50 are fed from the paper feeding unit. The images are sequentially transferred onto the transfer paper fed during the period. Further, the transfer paper onto which the toner image has been transferred is separated from the peripheral surface of the electrostatic latent image carrier 20, introduced into the fixing device and fixed, and then copied to the outside of the image forming apparatus 100. Printed out. On the other hand, after the toner image is transferred, the surface of the electrostatic latent image carrier 20 is cleaned by the cleaning device 60 after the remaining toner is removed, and then the static electricity is removed by the static eliminator 70 to repeatedly form images. used.

  The developing device 40 will be described in more detail. The developing device 40 has a developer container and a replenishment cartridge, and a replenishment developer comprising a replenishment carrier and toner in the replenishment cartridge. Is supplied to the developer accommodating portion by the replenishing means. The initial developer composed of the initial carrier and toner in the developer accommodating portion is replaced by a replenishing developer that is replenished as needed, and a toner image is formed by the replaced developer in the developer accommodating portion.

(Process cartridge)
The process cartridge of the present invention includes the electrostatic latent image carrier, the electrostatic latent image formed on the electrostatic latent image carrier, the carrier including at least the initial carrier, and the toner. The developing means for developing with the developer accommodated in the developer accommodating portion having the developer to form a toner image is integrally supported.
The developing means includes the replenishment member that replenishes the developer storage unit with the replenishment developer from the replenishment cartridge having the replenishment developer including at least the replenishment carrier. .
The process cartridge of the present invention includes the developer of the present invention, and can be detachably provided in various electrophotographic image forming apparatuses, facsimiles, and printers, and is detachably provided in the image forming apparatus of the present invention. More preferably.

<Embodiment of Process Cartridge>
An embodiment of the process cartridge of the present invention will be described with reference to FIG.
The process cartridge 10 includes a photosensitive member 11 that is an electrostatic latent image carrier, a charging device 12 that charges the photosensitive member 11, and a developer that includes the electrostatic latent image formed on the photosensitive member 11 and the carrier and toner of the present invention. A developing device 13 that forms a toner image by developing using a toner and a cleaning device 14 that removes the toner remaining on the photoconductor 11 after the toner image formed on the photoconductor 11 is transferred to a recording medium are integrated. The process cartridge 10 is detachable from the main body of an image forming apparatus such as a copying machine or a printer.
The process cartridge according to the present invention develops the electrostatic latent image carrier and the electrostatic latent image formed on the electrostatic latent image carrier using the developer containing the carrier and toner of the present invention. The developing means for forming the toner image is at least integrally supported. Therefore, the process cartridge according to the present invention is not necessarily provided for the other configurations described above.

  Hereinafter, a method for forming an image using the image forming apparatus equipped with the process cartridge 10 will be described. First, the photoconductor 11 is rotationally driven at a predetermined peripheral speed, and the charging device 12 uniformly charges the peripheral surface of the photoconductor 11 to a predetermined positive or negative potential. Next, exposure light is irradiated onto the peripheral surface of the photoconductor 11 from an exposure apparatus (not shown) such as a slit exposure type exposure apparatus or an exposure apparatus that performs scanning exposure with a laser beam, and electrostatic latent images are sequentially formed. Further, the electrostatic latent image formed on the peripheral surface of the photoconductor 11 is developed by the developing device 13 using the developer containing the carrier and toner of the present invention to form a toner image. Next, the toner image formed on the peripheral surface of the photoconductor 11 is fed between the photoconductor 11 and the transfer device (not shown) from the paper feed unit (not shown) in synchronization with the rotation of the photoconductor 11. Then, the image is sequentially transferred onto a transfer sheet that is a recording medium. Further, the transfer paper onto which the toner image has been transferred is separated from the peripheral surface of the photoconductor 11 and is introduced into a fixing device (not shown) and fixed, and then copied to the outside of the image forming apparatus. Printed out. On the other hand, after the toner image is transferred, the surface of the photoconductor 11 is cleaned by removing residual toner by the cleaning device 14, and then neutralized by a static eliminator (not shown) and repeatedly used for image formation. Is done.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. “Part” represents part by mass.

<Conductive fine particle production example 1>
100 g of aluminum oxide (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this liquid was heated to 65 ° C. A suspension of 155 g of stannic chloride and 4.65 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass aqueous ammonia was added to the suspension for 3 hours so that the pH of the suspension would be 7-8. It was added dropwise over a period of minutes. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 5 hours to obtain conductive fine particles 1. The volume average particle diameter of the obtained conductive fine particles was 600 nm as measured based on the measurement method described above.

<Conductive fine particle production example 2>
100 g of aluminum oxide (AKP-50 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this liquid was heated to 65 ° C. To this suspension, a solution of 29 g of stannic chloride and 0.87 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of aqueous ammonia was applied over 35 minutes so that the pH of the suspension would be 7-8. And dripped. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 5 hours to obtain conductive fine particles 2. The obtained conductive fine particles had a volume average particle size of 350 nm.

<Conductive fine particle production example 3>
100 g of aluminum oxide (AKP-20 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this liquid was heated to 65 ° C. To this suspension, a solution of 498 g of stannic chloride and 14.94 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass aqueous ammonia was added for 9 hours 58 so that the suspension had a pH of 7-8. It was added dropwise over a period of minutes. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 5 hours to obtain conductive fine particles 3. The obtained conductive fine particles had a volume average particle size of 900 nm.

<Conductive fine particle production example 4>
100 g of aluminum oxide (AKP-50 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this liquid was heated to 65 ° C. To this suspension, a solution of 23 g of stannic chloride and 0.69 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass of aqueous ammonia were added over 28 minutes so that the pH of the suspension would be 7-8. And dripped. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 5 hours to obtain conductive fine particles 4. The obtained conductive fine particles had a volume average particle size of 330 nm.

<Conductive fine particle production example 5>
100 g of aluminum oxide (AKP-20 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this liquid was heated to 65 ° C. To this suspension, a solution of 537 g of stannic chloride and 16.11 g of phosphorus pentoxide in 1 liter of 2N hydrochloric acid and 12% by mass ammonia water was added for 10 hours 44 hours so that the pH of the suspension would be 7-8. It was added dropwise over a period of minutes. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 5 hours to obtain conductive fine particles 5. The obtained conductive fine particles had a volume average particle size of 920 nm.

<Resin synthesis example 1>
300 g of toluene was charged into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream.
Then, 84.4 g of ₃ -methacryloxypropyltris (trimethylsiloxy) silane represented by CH ₂ = CMe—COO—C ₃ H ₆ —Si (OSiMe ₃ ) ₃ (wherein Me is a methyl group). (200 mmol: Silaplane TM-0701T / manufactured by Chisso Corporation), 3-methacryloxypropylmethyldiethoxysilane 39 g (150 mmol), methyl methacrylate 65.0 g (650 mmol), and 2,2′-azobis A mixture of 0.58 g (3 mmol) of 2-methylbutyronitrile was added dropwise over 1 hour.
After completion of the dropwise addition, a solution prepared by dissolving 0.06 g (0.3 mmol) of 2,2′-azobis-2-methylbutyronitrile in 15 g of toluene was further added (2,2′-azobis-2-methylbutyrate). The total amount of rhonitrile (0.64 g = 3.3 mmol) was mixed at 90 ° C. to 100 ° C. for 3 hours and radical copolymerized to obtain a methacrylic copolymer 1.
The weight average molecular weight of the obtained methacrylic copolymer was 33,000.
Subsequently, it diluted with toluene so that the non volatile matter of this methacrylic copolymer solution might be 25 mass%. The viscosity of the copolymer solution thus obtained was 8.8 mm ² / s, and the specific gravity was 0.91.
In addition, the weight average molecular weight was calculated | required in standard polystyrene conversion using the gel permeation chromatography. The viscosity was measured at 25 ° C. according to JIS-K2283. The nonvolatile content was calculated according to the following formula by weighing 1 g of the coating composition in an aluminum dish and measuring the mass after heating at 150 ° C. for 1 hour.
Nonvolatile content (%) = (mass before heating−mass after heating) × 100 / mass before heating

<Carrier Production Example 1>
[Carrier coating layer]
-Methacrylic copolymer 1 (solid content 25% by mass) 173.2 parts by mass-Silicone resin solution [solid content 20% by mass]
(SR2410: manufactured by Toray Dow Corning Silicone Co.) 216.6 parts by mass Titanium catalyst [solid content 95% by mass]
(TC-750: manufactured by Matsumoto Fine Chemical Co., Ltd.) 11.0 parts by mass Aminosilane [solid content: 100% by mass]
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.) 7.2 parts by mass-Conductive fine particles 1 150.0 parts by mass-Toluene 600.0 parts by mass

  After adding the raw material excluding the titanium catalyst and dispersing with 1,000 parts of 0.5 mm Zr beads for 1 hour with a paint shaker, the beads were removed with a mesh and allowed to stand for 10 minutes to obtain a resin coating film forming solution. . Average particle diameter: 35 μm calcined ferrite powder (true specific gravity 5.5): 5,000 parts by mass as a core material, and a solution obtained by adding a titanium catalyst to the above coating film forming solution is applied to the core particle surface with a Spira coater (Okada Seiko) Applied to the coater at a temperature of 60 ° C. and dried. The obtained carrier was baked by being left at 210 ° C. for 1 hour in an electric furnace under a nitrogen atmosphere. After cooling, the ferrite powder bulk was crushed using a sieve having an aperture of 63 μm to obtain [Carrier 1] having a volume average particle size of 36 μm. Further, a replenishment developer [Carrier 1 '] was obtained in the same manner as described above except that aminosilane was changed to 11.9 parts by mass.

<Carrier production example 2>
In Carrier Production Example 1, [Carrier 2] and [Carrier 2 ′] having a volume average particle size of 36 μm were set in exactly the same manner as Carrier 1 and Carrier 1 ′, except that the conductive fine particles 2 were changed to 150 parts by mass. Obtained.

<Carrier Production Example 3>
In Carrier Production Example 1, [Carrier 3] and [Carrier 3 ′] having a volume average particle size of 36 μm are exactly the same as Carrier 1 and Carrier 1 ′, except that the conductive fine particles 3 are changed to 150 parts by mass. Obtained.

<Carrier Production Example 4>
[Carrier 4] having a volume average particle diameter of 36 μm was obtained in the same manner as in Carrier 1 except that the amount of aminosilane was 5.4 parts by mass in Carrier Production Example 1. Further, a replenishment developer [Carrier 4 ′] was obtained in the same manner as described above except that aminosilane was changed to 14.7 parts by mass.

<Carrier Production Example 5>
[Carrier 5] having a volume average particle size of 36 μm was obtained in the same manner as Carrier 1 except that the amount of aminosilane was 9.5 parts by mass in Carrier Production Example 1. Further, a replenishment developer [Carrier 5 ′] was obtained in the same manner as described above except that aminosilane was changed to 11.2 parts by mass.

<Carrier Production Example 6>
[Carrier 6] having a volume average particle size of 36 μm in exactly the same manner as Carrier 1 except that the prescription amount of the conductive fine particles was 110 parts by mass and the prescription amount of aminosilane was 5.5 parts by mass in Carrier Production Example 1. Got. Further, a replenishment developer [Carrier 6 ′] was obtained in the same manner as described above except that aminosilane was changed to 9.8 parts by mass.

<Carrier Production Example 7>
[Carrier 7] having a volume average particle size of 36 μm in exactly the same manner as Carrier 1 except that the prescription amount of conductive fine particles was 240 parts by mass and the prescription amount of aminosilane was 10.3 parts by mass in Carrier Production Example 1. Got. Further, a replenishment developer [Carrier 7 ′] was obtained in the same manner as described above except that aminosilane was changed to 15.9 parts by mass.

<Carrier Production Example 8>
[Carrier 8] having a volume average particle size of 36 μm in exactly the same manner as Carrier 1 except that the prescription amount of conductive fine particles was 100 parts by mass and the prescription amount of aminosilane was 5.3 parts by mass in Carrier Production Example 1. Got. Further, a replenishment developer [Carrier 8 ′] was obtained in the same manner as above except that aminosilane was changed to 9.5 parts by mass.

<Carrier Production Example 9>
[Carrier 9] having a volume average particle size of 36 μm in exactly the same manner as Carrier 1 except that the amount of conductive fine particles was 270 parts by mass and the amount of aminosilane was 10.5 parts by mass in Carrier Production Example 1. Got. Further, a replenishment developer [Carrier 9 ′] was obtained in the same manner as described above except that aminosilane was changed to 16.6 parts by mass.

<Carrier Production Example 10>
In Carrier Production Example 1, [Carrier 10] and [Carrier 10 ′] having a volume average particle diameter of 36 μm are the same as those of Carrier 1 and Carrier 1 ′ except that the conductive fine particles 4 are changed to 150 parts by mass. Obtained.

<Carrier Production Example 11>
In Carrier Production Example 1, [Carrier 11] and [Carrier 11 ′] having a volume average particle size of 36 μm are the same as those of Carrier 1 and Carrier 1 ′ except that the conductive fine particles 5 are changed to 150 parts by mass. Obtained.

<Toner 1>
-Synthesis of polyester resin A-
Into a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 65 parts of an ethylene oxide 2-mole adduct of bisphenol A, 86 parts of a propion oxide 3-mole adduct of bisphenol A, 274 parts of terephthalic acid and 2 parts of dibutyltin oxide And allowed to react at 230 ° C. for 15 hours under normal pressure. Next, it was made to react under reduced pressure of 5 mmHg-10 mmHg for 6 hours, and the polyester resin was synthesize | combined. The obtained polyester resin A has a number average molecular weight (Mn) of 2,300, a weight average molecular weight (Mw) of 8,000, a glass transition temperature (Tg) of 58 ° C., an acid value of 25 mgKOH / g, and a hydroxyl value of It was 35 mgKOH / g.

-Synthesis of styrene acrylic resin A-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 300 parts of ethyl acetate, 185 parts of styrene, 115 parts of acrylic monomer and 5 parts of azobisisobutylnitrile were introduced, and the temperature was 65 ° C. (atmospheric pressure). ) For 8 hours. Next, 200 parts of methanol was added and stirred for 1 hour, and then the supernatant was removed and dried under reduced pressure to synthesize styrene-acrylic resin A. The obtained styrene acrylic resin A had Mw of 20,000 and Tg of 58 ° C.

-Synthesis of prepolymer (polymer capable of reacting with active hydrogen group-containing compound)-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, trimellitic anhydride 22 parts by mass and 2 parts by mass of dibutyltin oxide were charged and reacted at 230 ° C. for 8 hours under normal pressure. Subsequently, it was made to react under reduced pressure of 10 mmHg-15 mHg for 5 hours, and the intermediate polyester was synthesize | combined.
The obtained intermediate polyester has a number average molecular weight (Mn) of 2,100, a weight average molecular weight (Mw) of 9,600, a glass transition temperature (Tg) of 55 ° C., an acid value of 0.5, and a hydroxyl value of 49.
Next, 411 parts by mass of the intermediate polyester, 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate are charged in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, and reacted at 100 ° C. for 5 hours. Thus, a prepolymer (polymer capable of reacting with the active hydrogen group-containing compound) was synthesized.
The free isocyanate content of the obtained prepolymer was 1.60% by mass, and the solid content concentration of the prepolymer (after standing at 150 ° C. for 45 minutes) was 50% by mass.

-Synthesis of ketimine (the active hydrogen group-containing compound)-
In a reaction vessel equipped with a stir bar and a thermometer, 30 parts by mass of isophoronediamine and 70 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize a ketimine compound (the active hydrogen group-containing compound). The amine value of the obtained ketimine compound (the active hydrogen machine-containing compound) was 423.

-Preparation of master batch-
1,000 parts of water, 540 parts of carbon black Printex 35 (manufactured by Degussa) having a DBP oil absorption of 42 mL / 100 g and a pH of 9.5, and 1,200 parts of polyester resin A, Henschel mixer (manufactured by Mitsui Mining) And mixed. Next, the obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, then rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Corporation) to prepare a master batch.

-Preparation of aqueous medium-
An aqueous medium was prepared by mixing and stirring 306 parts of ion-exchanged water, 265 parts of a 10% by mass suspension of tricalcium phosphate, and 1.0 part of sodium dodecylbenzenesulfonate, and uniformly dissolving them.

-Measurement of critical micelle concentration-
The critical micelle concentration of the surfactant was measured by the following method. Using a surface tension meter Sigma (manufactured by KSV Instruments), analysis was performed using an analysis program in the Sigma system. Surfactant was dropped 0.01% by mass with respect to the aqueous medium, and the interfacial tension after stirring and standing was measured. From the obtained surface tension curve, the surfactant concentration at which the interfacial tension did not decrease even when the surfactant was dropped was calculated as the critical micelle concentration. When the critical micelle concentration of sodium dodecylbenzenesulfonate with respect to the aqueous medium was measured with a surface tension meter Sigma, it was 0.05% by mass with respect to the mass of the aqueous medium.

-Adjustment of toner material liquid-
In a beaker, 70 parts of polyester resin A, 10 parts of prepolymer and 100 parts of ethyl acetate were stirred and dissolved. As a release agent, 5 parts of paraffin wax (HNP-9, melting point 75 ° C., manufactured by Nippon Seiki Co., Ltd.), 2 parts of MEK-ST (Nissan Chemical Industry Co., Ltd.), and 10 parts of masterbatch were added. After 3 passes under the condition that the liquid feeding speed is 1 kg / hour, the peripheral speed of the disk is 6 m / second, and 80% by volume of zirconia beads having a particle diameter of 0.5 mm are filled, the ketimine 2.7 is used. Part was added and dissolved to prepare a toner material solution.

―Preparation of emulsion or dispersion―
150 parts by mass of the aqueous medium phase is placed in a container, and stirred at a rotational speed of 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and 100 parts by mass of the solution or dispersion of the toner material is added thereto. The mixture was added and mixed for 10 minutes to prepare an emulsified dispersion (emulsified slurry).

―Removal of organic solvent―
100 parts by mass of the emulsified slurry was charged into a Kolben equipped with a stirrer and a thermometer, and the solvent was removed at 30 ° C. for 12 hours while stirring at a stirring peripheral speed of 20 m / min.

-Washing-
After 100 parts by mass of the dispersion slurry was filtered under reduced pressure, 100 parts by mass of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered. To the obtained filter cake, 300 parts by mass of ion-exchanged water was added, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered twice. To the obtained filter cake, 20 parts by mass of a 10% by mass aqueous sodium hydroxide solution was added, mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure. To the obtained filter cake, 300 parts by mass of ion-exchanged water was added, mixed with a TK homomixer (at 12,000 rpm for 10 minutes), and then filtered. To the obtained filter cake, 300 parts by mass of ion-exchanged water was added, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered twice. Furthermore, 20 mass parts of 10 mass% hydrochloric acid was added to the obtained filter cake, mixed with a TK homomixer (at a rotation speed of 12,000 rpm for 10 minutes) and then filtered.

-Surfactant adjustment-
To the filter cake obtained by the above washing, 300 parts by mass of ion-exchanged water was added, and the electrical conductivity of the toner dispersion was measured when mixed with a TK homomixer (10 minutes at 12,000 rpm). The surfactant concentration of the toner dispersion was calculated from a calibration curve for surfactant concentration prepared in advance. From this value, ion-exchanged water was added so that the surfactant concentration was the target surfactant concentration of 0.05% by mass to obtain a toner dispersion.

―Surface treatment process―
The toner dispersion liquid adjusted to the predetermined surfactant concentration was heated for 10 hours at a heating temperature T1 = 55 ° C. in a water bath while mixing at 5000 rpm with a TK homomixer. Thereafter, the toner dispersion was cooled to 25 ° C. and filtered. Further, 300 parts by mass of ion-exchanged water was added to the obtained filter cake, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.

―Dry―
The obtained final filter cake was dried with a circulating dryer at 45 ° C. for 48 hours, and sieved with a mesh having an opening of 75 μm to obtain toner base particles 1.

―External treatment―
Further, with respect to 100 parts by mass of toner base particles 1, 3.0 parts by mass of hydrophobic silica having an average particle diameter of 100 nm, 0.5 parts by mass of titanium oxide having an average particle diameter of 20 nm, and hydrophobicity having an average particle diameter of 15 nm. 1.5 parts by mass of silica fine powder was mixed with a Henschel mixer to obtain [Toner 1].

Example 1
[Carrier 1]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer.
The developer for replenishment was prepared using [Carrier 1 ′] and the toner so that the carrier ratio was 10% by mass.

<Image evaluation>
Using the developer thus obtained, it was set in RICOH Pro C901 (digital color copier / printer multifunction machine manufactured by Ricoh Co., Ltd.), and the first image evaluation was performed with an output of 90 sheets per minute. Specifically, the image density after running 1 million sheets, background fogging, and toner scattering were evaluated at an image area ratio of 50%. The evaluation method is shown below.

<< Image density >>
After outputting the solid image on 6,000 paper manufactured by Ricoh Co., Ltd., the image density was measured by X-Rite (manufactured by X-Rite). In the measurement, 1,000 sheets were output continuously, and image density measurement was performed every 10 sheets. Of the 100 sheets measured, the one with the lowest image density was adopted as the evaluation result. The evaluation criteria for the measured values are as follows.
-Evaluation criteria-
◎: 1.5 or more and less than 2.0 ○: 1.3 or more and less than 1.5 Δ: 1.2 or more and less than 1.3 ×: less than 1.2

<< Toner scattering >>
Toner scattering was evaluated by visual observation of toner scattering after output. The toner scattering was evaluated by the amount of toner scattered around the developing roller. The evaluation criteria are as follows.
-Evaluation criteria-
◎: No toner scattering observed ○: Slight toner scattering observed but no problem Δ: Toner scattering slightly conspicuous State

<< Skin Cover >>
For background fogging, the blank image is stopped during development after output, and the toner on the photoconductor after development is transferred to tape, and the difference from the image density of the untransferred tape is determined by 938 Spectrodensitometer (X-Rite). ). The smaller the difference in image density, the better the background dirt. The evaluation criteria are as follows.
-Evaluation criteria-
◎: ΔID is less than 0.005 ○: ΔID is 0.005 or more and less than 0.01

  In addition, a second image evaluation was performed using the obtained developer using a RICOH Pro C901 (Ricoh Co., Ltd. digital color copier / printer multifunction machine). Specifically, the image density after running 1,000,000 sheets with an image area ratio of 0.5% was measured in the same manner as the above-mentioned << image density >> evaluation method. Further, the carrier adhesion after running 1 million sheets was evaluated by the following method at an image area ratio of 0.5%.

<< Carrier adhesion >>
The carrier adhesion (solid portion) was evaluated by the following method.
・ Development gap (photosensitive member-developing sleeve): 0.3 mm
・ Doctor gap (developing sleeve-doctor): 0.65mm
-Photoconductor linear velocity: 440 mm / sec
(Development sleeve linear velocity) / (photosensitive member linear velocity): 1.80
-Write density: 600 dpi
・ Charging potential (Vd): -600V
-Potential after exposure of the portion corresponding to the image portion (solid document): -100V
・ Development bias: DC-500V
Under the above development conditions, the number of carriers attached to a solid image (30 mm × 30 mm) of RICOH Pro C901 was counted on the photoconductor to evaluate the solid carrier adhesion. The evaluation criteria are as follows.
-Evaluation criteria-
◎: Very good ○: Good △: Usable ×: Poor

For the developer used in Example 1, the above-described measurement methods were used, and the initial carrier charge amount A, the replenishment carrier charge amount B, the fine particle volume average particle size D, and the coating layer thickness. h was measured.
Table 1 shows the physical properties of the developer.
Table 2 shows the results of the above evaluations performed using the developer of Example 1.

(Example 2)
[Carrier 2]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 2 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 3)
[Carrier 3]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 3 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

Example 4
[Carrier 4]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 4 ′] and the toner so that the carrier ratio was 5% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 5)
[Carrier 5]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. Further, the developer for replenishment was prepared using [Carrier 5 ′] and the toner so that the carrier ratio was 40% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 6)
[Carrier 1]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 1 ′] and the toner so that the carrier ratio was 9% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 7)
[Carrier 1]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 1 ′] and the toner so that the carrier ratio was 18% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 8)
[Carrier 6]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. Further, the developer for replenishment was prepared using [Carrier 6 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

Example 9
[Carrier 7]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 7 '] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 10)
[Carrier 8]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 8 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Example 11)
[Carrier 9]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. The developer for replenishment was produced using [Carrier 9 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 1)
[Carrier 10]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 10 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 2)
[Carrier 11]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 11 ′] and the toner so that the carrier ratio was 10% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 3)
[Carrier 4]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 4 '] and the toner so that the carrier ratio was 3% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 4)
[Carrier 5]: 930 parts by mass of toner and 1:70 parts by mass of toner were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer to prepare an initial developer. Further, the developer for replenishment was prepared using [Carrier 5 ′] and the toner so that the carrier ratio was 45% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 5)
[Carrier 1]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 1 ′] and the toner so that the carrier ratio was 7% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

(Comparative Example 6)
[Carrier 1]: 930 parts by mass and toner 1:70 parts by mass were mixed and stirred for 5 minutes at 81 rpm using a turbuler mixer to prepare an initial developer. The developer for replenishment was prepared using [Carrier 1 ′] and the above toner so that the carrier ratio was 20% by mass. Table 1 shows the physical properties of the developer. Table 2 shows the results evaluated in the same manner as in the examples.

Aspects of the present invention are as follows, for example.
<1> An electrostatic latent image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier, and an electrostatic latent image formed on the electrostatic latent image carrier A developing means for developing an image using the developer contained in a developer containing portion containing a carrier containing at least an initial carrier and a developer containing toner, and forming a toner image; An image forming apparatus having transfer means for transferring the toner image formed on the image carrier to a recording medium,
The developing means includes a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
The image forming apparatus is characterized in that 2.0> (B−A) × C> 0.95.
<2> The image forming apparatus according to <1>, wherein the toner contains a crystalline polyester resin.
<3> The content ratio a of the fine particles in the coating layer in the initial carrier and the replenishment carrier is
The image forming apparatus according to any one of <1> to <2>, wherein 50% by mass ≦ a ≦ 70% by mass.
<4> The ratio (D / h) between the volume average particle diameter D (nm) of the fine particles in the initial carrier and the replenishment carrier and the film thickness h (nm) of the coating layer,
The image forming apparatus according to any one of <1> to <3>, wherein 1.5 <(D / h) <2.0.
<5> The image forming apparatus according to any one of <1> to <4>, wherein the initial carrier and the replenishment carrier have a volume average particle diameter of 20 μm or more and 45 μm or less.
<6> The image forming apparatus according to any one of <1> to <5>, wherein the fine particles in the coating layer of the initial carrier and the replenishment carrier are conductive fine particles.
<7> Co-weight in which the resin component in the coating layer of the initial carrier and the replenishment carrier includes at least the A part represented by the following general formula (A) and the B part represented by the following general formula (B) The image forming apparatus according to any one of <1> to <6>, including a resin obtained by heat-treating the combined body.

(In the formula, R ¹ , m, R ² , R ³ , X, and Y are as follows.)
R ¹ : Either a hydrogen atom or a methyl group m: an integer of 1 to 8 R ² : an alkyl group having 1 to 4 carbon atoms R ³ : an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 4 carbon atoms Any of the groups X = 10 mol% to 90 mol%
Y = 10 mol% to 90 mol%)
<8> An electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier and the electrostatic latent image formed on the electrostatic latent image carrier are accommodated in the developer accommodating portion. A development process for forming a toner image by developing using a carrier containing at least an initial carrier and a developer containing toner, and recording the toner image formed on the electrostatic latent image carrier An image forming method including a transfer step of transferring to a medium,
The developing step includes a replenishment process for replenishing the developer storage unit with a replenishment developer including at least a replenishment carrier from a replenishment cartridge;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95.
<9> The electrostatic latent image carrier and the electrostatic latent image formed on the electrostatic latent image carrier are placed in a developer container having a carrier containing at least an initial carrier and a developer containing toner. A developing unit that develops using the developer stored therein and forms a toner image is a process cartridge that is integrally supported,
The developing means includes a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
In addition, the process cartridge is characterized in that 2.0> (B−A) × C> 0.95.

DESCRIPTION OF SYMBOLS 1a Electrode 1b Electrode 2 Fluororesin container 3 Electrostatic latent image developing carrier 10 Process cartridge 11 Electrostatic latent image carrier 12 Charging device 13 Developing device 14 Cleaning device 20 Electrostatic latent image carrier 32 Charging device 33 Exposure device 40 Developing device 50 Transfer device 60 Cleaning device 70 Static elimination device 100 Image forming device

JP 2008-262155 A JP 2011-27996 A Japanese Patent No. 3562285 Japanese Patent No. 3777778

Claims (9)

An electrostatic latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier;
Developing the electrostatic latent image formed on the electrostatic latent image carrier using the developer contained in a developer containing portion having a carrier containing at least an initial carrier and a developer containing toner. Developing means for forming a toner image;
An image forming apparatus having transfer means for transferring the toner image formed on the electrostatic latent image carrier to a recording medium,
The developing means includes a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95.   The image forming apparatus according to claim 1, wherein the toner contains a crystalline polyester resin. The content ratio a of the fine particles in the coating layer in the initial carrier and the replenishment carrier is
The image forming apparatus according to claim 1, wherein 50% by mass ≦ a ≦ 70% by mass. The ratio (D / h) between the volume average particle diameter D (nm) of the fine particles in the initial carrier and the replenishment carrier and the film thickness h (nm) of the coating layer is
The image forming apparatus according to claim 1, wherein 1.5 <(D / h) <2.0.   The image forming apparatus according to claim 1, wherein the initial carrier and the replenishment carrier have a volume average particle diameter of 20 μm or more and 45 μm or less.   6. The image forming apparatus according to claim 1, wherein the fine particles in the coating layer of the initial carrier and the replenishment carrier are conductive fine particles. Heating the copolymer in which the resin component in the coating layer of the initial carrier and the replenishment carrier includes at least an A part represented by the following general formula (A) and a B part represented by the following general formula (B) The image forming apparatus according to claim 1, comprising a resin obtained by processing.

(In the formula, R ¹ , m, R ² , R ³ , X, and Y are as follows.)
R ¹ : Either a hydrogen atom or a methyl group m: an integer of 1 to 8 R ² : an alkyl group having 1 to 4 carbon atoms R ³ : an alkyl group having 1 to 8 carbon atoms, and an alkoxy having 1 to 4 carbon atoms Any of the groups X = 10 mol% to 90 mol%
Y = 10 mol% to 90 mol%) An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier;
The electrostatic latent image formed on the electrostatic latent image carrier is developed using a carrier containing at least an initial carrier and a developer containing toner, which are accommodated in a developer accommodating portion, and a toner image A development step to form
A transfer step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium,
The developing step includes a replenishment process for replenishing the developer storage unit with a replenishment developer including at least a replenishment carrier from a replenishment cartridge;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95. An electrostatic latent image carrier;
Developing the electrostatic latent image formed on the electrostatic latent image carrier using the developer contained in a developer containing portion having a carrier containing at least an initial carrier and a developer containing toner. And a developing means for forming a toner image is a process cartridge that is integrally supported,
The developing means includes a replenishing member that replenishes the developer containing portion with the replenishment developer from a replenishment cartridge having a replenishment developer including at least a replenishment carrier;
The initial carrier and the replenishment carrier are composed of magnetic core material particles and a coating layer that covers the surface of the core material particles. The coating layer has fine particles having a volume average particle size of 340 nm to 910 nm. Including
The charge amount of the initial carrier with respect to the toner is A (μC / g), the charge amount of the replenishment carrier with respect to the toner is B (μC / g), and the replenishment carrier in the replenishment developer. When the mass ratio of C is C,
The mass ratio C of the replenishment carrier is 0.05 to 0.40,
And 2.0> (B−A) × C> 0.95.