JP5506438B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method for forming an image using an electrophotographic process.

  As a technology for suppressing image flow and maintaining the image bearing member (photoreceptor) with a long life, the peripheral surface of the photoreceptor is improved by increasing the hardness of the peripheral surface of the photoreceptor to suppress wear, and by incorporating abrasive particles into the toner. There has been disclosed a technique for removing discharge products adhering to the peripheral surface of the photoconductor by adhering to the surface and polishing the peripheral surface of the photoconductor with abrasive particles (see Patent Document 1).

  As another example of the polishing technique, a technique of externally or internally adding abrasive particles having a Mohs hardness of 3.5 or more and a volume average particle size of 0.1 to 10 μm containing calcium carbonate to a resin-coated carrier, on the surface of a resin-coated carrier A technique for fixing abrasive particles having a Mohs hardness of 5 or more is disclosed (see Patent Document 2).

  In addition, as a technology for extending the life and stability of two-component developers, the carrier characteristics are specified, and resin coating is applied so that the spherical ferrite surface has irregularities based on fine crystal particles and the irregularities are exposed. And the technique which suppresses the density | concentration fluctuation | variation by long-term use is proposed (refer patent document 3). Further, a technique for extending the charging uniformity and carrier life by coating the core particle surface with a coating resin at a ratio of 80% or less is disclosed (see Patent Document 4).

JP-A-2005-208325 Japanese Patent Laid-Open No. 08-190227 Japanese Laid-Open Patent Publication No. 04-093954 Japanese Laid-Open Patent Publication No. 2005-172974

  An object of the present invention is to provide an image forming method that solves the above-described problems. That is, the present invention suppresses the influence of the charged product on the surface of the image carrier, prevents the image from flowing, suppresses the wear of the image carrier and the cleaning blade, and produces a high-quality image over a long period of time. It is an object of the present invention to provide an image forming method that can be provided.

To achieve the above object, the present invention comprises a charging step for charging an image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the image carrier;
Form a toner image a magnetic brush formed by two-component developer bias is supported on the applied surface of the developer carrying member by contacting the image bearing member, developing the electrostatic latent image A development process to
A transfer step of transferring the toner image to a recording medium;
A cleaning step of removing transfer residual toner from the surface of the image carrier after transfer ;
And at least Yusuke that image forming method,
The two-component developer contains a magnetic carrier and a toner,
The magnetic carrier,
Ri Ah magnetic carrier and a magnetic ferrite core particles and a resin,
In a reflected electron image of the magnetic carrier photographed at an acceleration voltage of 2.0 kV using a scanning electron microscope ,
Area of the portion derived from the metal oxide, the relative magnetic grain projected area of the carrier is 10.0 area% or less 0.5 area% or more,
Average area value of the portion from the metallic oxides are at 0.45 [mu] m ² or more 1.40 .mu.m ² or less,
The contact portion between the magnetic brush and said image bearing member, an image forming method characterized by number average particle diameter is interposed a basic inorganic compound is 30nm or more 300nm or less.

  As a result of the study by the present inventors, in order to suppress the deterioration of the image carrier and further suppress the reduction of the friction characteristics, a basic inorganic compound having a predetermined particle diameter is supplied to the surface of the image carrier, thereby It turns out that the flow can be suppressed. Further, it has been found that the effect of suppressing image flow can be maintained for a long time by rubbing with a carrier of a two-component developer having a specific core exposed area, and the wear of the cleaning member can be suppressed.

  With the configuration of the present invention, it is possible to prevent the surface of the image carrier from being deteriorated and to prevent the image from flowing. In addition, the load received by the cleaning blade and the image carrier is suppressed, and wear and tear thereof are prevented, and stable good cleaning properties are maintained over a long period of time, and stable image characteristics are maintained at a high level.

It is a figure which shows an example of the embodiment of the image forming apparatus concerning this invention. It is a figure which shows an example of the projection image which visualized the reflected electron image mainly of the magnetic carrier of this invention. It is a figure which shows an example of the state which image-processed the magnetic carrier particle and extracted the magnetic carrier particle. It is a figure which shows an example of the state which image-processed the magnetic carrier particle | grains and extracted the part originating in the metal oxide on the magnetic carrier particle | grain surface. It is a conceptual diagram for demonstrating an image processing procedure. It is a conceptual diagram for demonstrating the data-analysis procedure after an image process. It is a conceptual diagram for demonstrating the data-analysis procedure after an image process. It is an electron microscope (SEM) observation figure of an example of an inorganic basic compound in the present invention. It is a figure which shows an example of the laminated constitution of the photoreceptor in this invention. It is a figure which shows an example of the image formed at the time of the durability test in the Example and comparative example of this invention. 4A and 4B are schematic diagrams for explaining a contact state between the cleaning blade and the photosensitive member, where FIG. 5A is a state when the cleaning blade is installed (the photosensitive member is in a stationary state), and FIG. It is a figure for demonstrating the measurement site | part of a cleaning blade wear, and the depth D and the width W, (a) is an example of the wear state of a cleaning blade, (b) is a blade cross section in the state of (a). (C) is another example of the worn state of the cleaning blade, and (d) is a blade cross-sectional model diagram in the state of (c). It is a graph for demonstrating discharge current.

  Hereinafter, the present invention will be described in detail.

FIG. 1 shows an outline of an image forming apparatus according to the image forming method of the present invention.
The image carrier 101 is a rotatable drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive member), and is rotationally driven in a direction indicated by an arrow X at a predetermined surface speed by a driving mechanism (not shown). The photosensitive member 101 may have a known shape such as a belt shape in addition to the cylindrical shape as shown in the figure. Around the photosensitive member 101, a charging unit 102 for charging the photosensitive member, a latent image forming signal 103 added by a latent image (electrostatic latent image) forming unit (not shown), a developing unit 104, a transfer unit 105, and a cleaning unit 106 is arranged. The charging means 102 can use a known charging member and charging method. In this example, a roller-type charging member (referred to as a charging roller) is used in a contact system, and a vibration bias in which a DC bias is superimposed on an AC bias is applied (AC system) to obtain the dark portion potential VD of the photoreceptor 101. -650 [V]. The uniformly charged photoreceptor 101 forms a latent image by a known latent image formation signal 103. In this example, a latent image is formed by an image exposure method so that the light portion potential VL of the photosensitive member 101 is −200 [V] at a position facing a developing unit 104 described later. In accordance with the latent image formed on the photoreceptor 101, a toner image is formed by the developing unit 104 using a two-component developer composed of toner and carrier, and transferred to a transfer material (recording medium) P by the transfer unit 105. The Any known transfer means and method can be used. Details of the development process will be described later. The photoconductor (photoconductor after transfer) 101 that has undergone the transfer process is subjected to a cleaning unit 106 to remove residues such as a transfer residual developer and paper dust, and is subjected to the next image forming process.

・ Discharge current Idis
As described above, the charging roller 102 is applied with an AC charging bias in which a DC bias is superimposed on a sinusoidal AC bias. When no discharge occurs, a linear relationship is established between the applied AC voltage Vac (amplitude; Vpp) and the charging AC current Iac according to the impedance between the charging roller 102 and the photosensitive member 101.
On the other hand, when discharge is occurring, Iac ≧ Iz (Iz is a broken line portion in the discharge region of FIG. 9). The difference Idis between Iac and Iz is defined as the discharge current amount.
Since an electrical transient phenomenon is included when discharge is occurring, it is difficult to theoretically obtain the discharge current amount Idis. Further, the Idis is not always constant because it is easily affected by temperature and humidity, contact conditions of the charging roller 102, physical properties, dirt caused by a developer, and the like. Therefore, it is necessary to obtain the Idis for each printing operation or for every predetermined time.
The Idis is calculated by the following formula 1.
Idis = Iac−α · Vac (Formula 1)
The proportional constant α is obtained from Iac and Vac in an undischarged state.

In the present embodiment, the evaluation is performed while controlling the discharge current amount Idis to be constant. This control method will be described below.
The image forming apparatus of this example includes a controller (not shown) and current detection means (not shown). With these and a power source (not shown), at the time of non-image formation, one point of AC voltage (Vpp) in the undischarged region and two points or more of AC voltage are applied in the discharge region, and the total current Iac at that time is measured.
The controller measures the current Iac at a point of AC voltage 0 as an undischarged region (Iac and Idis are both 0 when Vpp = 0) and a plurality of AC voltages in the discharge region, and performs an approximation process from each voltage and current value. Do. Thereby, the applied voltage Vpp corresponding to the desired discharge current Idis is calculated and applied to the charging roller 102 from the power source. In the case of the current control method, instead of the current detection means, Iac of the undischarged area and the discharge area is applied as voltage detection means, and Iac corresponding to the desired Idis is obtained and applied as described above. What should I do? When image formation is performed continuously, the above operation can be performed between image formations.

Cleaning means The cleaning means 106 has a cleaning blade 107 made of an elastic member such as polyurethane rubber. The cleaning blade 107 is held by a known cleaning blade holding means (not shown), and is brought into contact with the photosensitive member 101 with a predetermined contact pressure or an entrance amount and a set angle θ. The rubber hardness (JIS A), contact pressure, and set angle θ of the cleaning blade 107 can be used within a known range. Further, it is preferable that the ratio T / L between the thickness T and the free length L of the cleaning blade is 0.2 or more, because the cleaning blade can be prevented from being bent and the cleaning blade edge can be stably brought into contact with the photosensitive member. .

  Further, from the viewpoint of the life of the system, it is also preferable to use the cleaning blade 107 having a specified physical property of 100% modulus and elongation at break.

  At the time of image formation, the tip of the cleaning blade 107 is pulled from the contacted photosensitive member 101 from the state shown in FIG. 7A and bent as shown in FIG. 7B. The wear of the cleaning blade 107 is considered to be caused by abrupt pulling of the cleaning blade at the contact portion with the photosensitive member due to an increase in local friction or foreign matter or abnormal load. When the image to be formed is localized or when the basic inorganic compound is replaced, the friction characteristics may be locally uneven in the longitudinal direction. Therefore, it is preferable that the cleaning blade is not easily deformed and has a strength against breakage such as tearing or cutting even if it is deformed. However, it is needless to say that the cleaning performance is not impaired.

The rubber properties are preferably 2940 ≦ 100% modulus ≦ 5880 [kN / m ² ] and elongation at break ≧ 300 [%]. By setting it as this range, while maintaining the state of the coating film by a lubrication agent suitably, abrasion of this cleaning blade can be suppressed.

In this example, as the cleaning blade 107, a plate-like blade having a rubber hardness of 73 [°], a 100% modulus of 3500 [kN / m ² ], a breaking elongation of 325 [%], and a thickness of 2 [mm] is freely used as a sheet metal. The sheet was fixed at a length of 8 [mm], and the sheet metal was brought into contact with the photoreceptor 101 by spring pressure. The contact pressure was 30.63 [N / m] (31.25 g / cm) at a set angle of 26 [°].

Basic inorganic compound and supply means The basic compound according to the present invention is present on the surface of the photoconductor 101 and suppresses oxidative deterioration of the photoconductor surface due to NOx as a discharge product in the charging step. To do. The basic compound is supplied evenly to the surface of the photoconductor, suppresses deterioration of the surface of the photoconductor due to the charged product, and is replaced with a new basic compound, thereby suppressing image flow over a long period of time.

  A basic compound reacts with an acid to form a salt, and is a basic organic compound such as ammonia or alkylamine, or a basic inorganic compound such as magnesium carbonate or calcium carbonate (hereinafter referred to as an inorganic base). Is mentioned.

  Many inorganic bases are in a solid state, and it is advantageous for protecting the surface of the photoreceptor or removing an oxidized and deteriorated basic compound and replacing it with an undegraded basic compound. In addition, the fact that the inorganic base neutralizes the acid is also known that the calcium carbonate contained in yellow sand neutralizes the acid rain.

  The basicity was determined by measuring the pH of the dispersion prepared using ion-exchanged water whose pH was adjusted to 7.0. The measuring method was performed at normal temperature (23 ± 2 ° C.) according to JIS K 5101-17-2 (normal temperature method).

  The pH is preferably higher than 7.0, but if it is too strong, the resulting salt may be strongly basic. Moreover, since the reactivity with a water | moisture content becomes high too much, excessive strong basicity is not preferable. Although it depends on conditions such as the amount of NOx, that is, the amount of discharge current, it is preferably 7.5 or more and 10 or less.

  The inorganic base preferably has a number average particle diameter of 30 nm to 300 nm. When it is 30 nm or more, it is easy to remove from the surface of the photoreceptor, and the flow suppressing effect is improved. On the other hand, in the case of a large particle diameter exceeding 300 nm, the detailed mechanism is unknown whether it is due to an increase in voids or a decrease in specific surface area, but the flow suppressing effect may be reduced. In particular, when an elastic blade is used for the cleaning means, a part of the particles having the above-mentioned particle size is removed by cleaning and a part of the particles passes through the nip portion of the cleaning means. It is effective.

  The particle size of the inorganic base is in the range of 100 to 1000 with a commercially available scanning electron microscope (SEM), and an arbitrary number of inorganic base particles are randomly selected and observed. The average particle size. For particles having a major axis and a minor axis, such as a cubic shape, the average value of the major axis and the minor axis was taken as the particle size of the observed particles.

  Among inorganic bases, calcium carbonate is excellent in lubricity, can suppress an increase in friction in the cleaning process, and is preferable for extending the life of the cleaning member 107 and the photoreceptor 101.

The means for supplying the inorganic base to the surface of the photoreceptor 101 includes, for example, a method of externally adding the developer to the developer in addition to the method of providing the inorganic base supply section means, but is not particularly limited. Further, the supply amount of the inorganic base depends on the configuration of the supply means and other various conditions, but preferably 1.0 × 10 ⁻¹⁰ g / mm ² or more per unit area of the photoreceptor can be supplied uniformly. . Moreover, it is preferable that it is 5 × 10 ⁻⁶ g / mm ² or less because the load on the supply member does not become excessive, and the life of the supply member and the inorganic base source can be extended.

  As shown in FIG. 1, the inorganic base supply means includes an inorganic base source 109 made of an inorganic base formed into a block shape, and a supply member 108 such as a brush roller. In this figure, an inorganic base source 109 is disposed in contact with the brush roller 108. Reference numeral 110 denotes an urging member that always brings the inorganic base source 109 into contact with the cleaning brush 108 with a predetermined pressing force.

  The brush roller 108 is driven with a relative speed difference from the photoconductor 101, and applies an inorganic base source 109 to the surface of the photoconductor 101 by an appropriate amount by the supply member 108. The inorganic base supply means may add a means (not shown) for leveling the inorganic base on the surface of the photoreceptor 101 or a flicker 111.

As the brush fiber, nylon, acrylic, polyester, or the like is suitably used, and conductivity may be imparted by including carbon or metal powder. The brush part preferably has a thickness of 3.33 [Tex] or less and a density of about 1500 to 80000 [lines / cm ² ] so that the surface of the photoreceptor and the untransferred toner can be uniformly contacted.

  The intrusion amount and driving speed when the brush roller 108 abuts on the photoconductor 101 depends on the fiber conditions of the brush roller 108 and the conditions of the photoconductor 101, but the intrusion amount is 3 [mm] or less. Preferably used. If the penetration amount is too large, the fibers of the photoreceptor 101 or the brush roller 108 may be easily worn out. Furthermore, it is preferable that the thickness is 0.5 [mm] or more because it contributes to the removal of foreign matter by contact with the photoreceptor 101.

  The drive speed is preferably about 5 to 50% relative to the surface speed of the photoconductor 101 in terms of the difference in relative speed with the photoconductor. In a state where there is almost no speed difference of less than 5 [%], the supply of the lubricant 109 tends to be uneven. On the other hand, if it exceeds 50 [%], the brush roller 108 or the photoreceptor 101 may be easily worn.

  Further, the inorganic base supply unit is disposed downstream of the transfer unit 105 and upstream of the charging unit 101 in the traveling direction of the photoconductor 101. Not only the downstream side of the cleaning unit, but also the downstream side of the transfer unit and the upstream side of the charging unit. For example, it can be arranged inside the cleaning means.

  When supplied externally to the developer, the flow characteristics were improved even with a very small amount of addition. Depending on the conditions such as the discharge current, it may be added within a range that does not adversely affect the developer characteristics such as development characteristics and transfer characteristics. Although it depends on external addition conditions and the like, a preferable range is 0.03 parts by mass or more and 2.50 parts by mass or less with respect to 100 parts by mass of the toner particles. Needless to say, it is preferably added in an amount and / or strength that does not hinder the function as a so-called developer, such as development density and transferability.

  It is also preferable to adjust the degree of hydrophobicity of the inorganic base as necessary. It is preferable that the methanol concentration (referred to as “hydrophobization degree”) at which the light transmittance according to the measurement of the degree of methanol hydrophobicity starts decreasing is 40% or more and 60% or less. When the degree of hydrophobicity is low, that is, the surface activity is high, the efficiency of action on acid and moisture is improved. When the degree of hydrophobicity was 60% or less, the effect of suppressing flow was improved. On the other hand, if it is lower than 40%, that is, if the degree of hydrophobicity is too low, the deteriorated inorganic base becomes excessive, resulting in a decrease in durability, and the fluctuation of friction due to the environment may increase.

  It is also effective to use an inorganic base having a high degree of hydrophobicity. When an inorganic base having a different degree of hydrophobization, specifically, an inorganic base having a hydrophobization degree of 75% or more is used in combination, excessive action is suppressed, and the flow deterrent effect is easily maintained over a long period of time. This is effective in reducing the environmental dependence of the frictional characteristics of the photoreceptor. An inorganic base having a high degree of hydrophobicity is more preferably used in an amount equal to or less than that of an inorganic base having a low degree of hydrophobicity.

  The degree of hydrophobicity in this case is determined by measuring the transmittance by methanol titration used when measuring the degree of hydrophobicity of methanol. Specifically, first, from the transmittance before the sample addition (starting point), the difference in transmittance from the point at which all the sample sinks below the liquid surface, that is, the point at which the transmittance is minimum (end point) ( Δ transmittance = transmittance at the start point−transmittance at the end point). The point at which 10% of Δ transmittance is reduced from the transmittance at the starting point, that is, the volume% of methanol used when the transmittance is 90%, is defined as the degree of hydrophobicity.

The measurement of the degree of hydrophobicity uses, for example, a powder wettability tester WET-100P manufactured by Reska Co., Ltd., and specific measurement operations include the methods exemplified below.
First, 70 ml of a hydrated methanol solution composed of 0% by volume of methanol and 100% by volume of water is placed in a flask and dispersed for 5 minutes with an ultrasonic disperser in order to remove bubbles and the like in the measurement sample. In this, 0.50 g of fine particles of a basic inorganic compound as a specimen are precisely weighed and added to prepare a sample solution for measurement. Next, while stirring the sample solution for measurement at a speed of 6.67 m / sec, methanol was added at 1.3 ml / min. Are continuously added at a dropping rate of 780 nm, the transmittance is measured with light having a wavelength of 780 nm, a methanol dropping transmittance curve is prepared, and the methanol concentration at which the transmittance is 90% is measured.

  In this measurement, the flask used was a circle having a diameter of 5 cm and a glass made of 1.75 mm, and the magnetic stirrer was a spindle having a length of 25 mm and a maximum diameter of 8 mm and was coated with a fluororesin. Use things.

Developing unit In the present invention, the developing unit 104 is based on a two-component developing system.
In the developing means 104, a nonmagnetic toner and a magnetic carrier are mixed and fed as a developer at a predetermined mixing ratio. Further, in the developing means 104, magnetic spikes made of a magnetic carrier and toner conveyed by a developer sleeve are formed. A non-magnetic developing sleeve which is a developer carrying member includes a fixed magnet roller. On the developer carrier, the magnetic carrier forms a magnetic spike in a state where the magnetic carrier particles are in contact with each other at points. The developing means 104 and the surface of the photoreceptor 101 are in contact with each other while being driven with a relative speed difference. In this contact area (referred to as a development nip), the toner is developed in accordance with the applied development bias and the latent image, and the surface of the photoreceptor 101 is in a state where the magnetic spike is interposed with the inorganic base. Rubbing. Note that the frequency of the developing bias is appropriately adjusted according to the surface speed of the photoreceptor 101.

In the developing means of the present invention, it is preferable that the surface of the photoreceptor is uniformly rubbed when the photoreceptor, developer carrier, and magnetic brush satisfy the following formula 2.
3 ≧ | Vsl−Vdr | · m · a · h / Vdr ≧ 0.7 (Expression 2)
here,
Vsl: peripheral speed of developer carrying member (mm / second)
Vdr: Peripheral speed of photoconductor (mm / sec)
h: Development nip (length with which the magnetic brush contacts the photoreceptor) (mm)
m: sectional area of the magnetic brush (mm ² )
a: Magnetic brush density (lines / mm ² )
It is.
The developing nip h is the length of the area where the magnetic brush on the developing sleeve contacts the photoconductor in the circumferential direction of the photoconductor. The cross-sectional area of the magnetic brush is the average value of the cross-sectional area of the magnetic brush on the developing sleeve at the height at which it contacts the photoconductor, and the magnetic brush density is determined per unit area of the photoconductor in the nip region. It is an average value of the number of magnetic brushes which contact.

When the length in the longitudinal direction of the photosensitive member 101 is standardized and the magnetic brush density on the developing sleeve is a (lines / mm ² ) and the magnetic brush cross-sectional area is m (mm ² / lines), unit time The area of the magnetic brush contacting the unit area on the photosensitive drum is expressed by the following equation 3. The photosensitive member comes into contact with the magnetic brush in the developing nip section, and the time required to pass through the nip is expressed by the following equation 4. Accordingly, the area S that contacts the magnetic brush, that is, is rubbed per unit length of the photosensitive member, is expressed by the following equation (5). The larger the area S, the closer the surface of the photoconductor and the magnetic brush are slid.
m · a · | Vsl−Vdr | (mm ² / sec) (Formula 3)
h / Vdr (sec) (Formula 4)
S = | Vsl−Vdr | · m · a · h / Vdr (Formula 5)
When the value of S is 0.7 or more and 3.0 or less, the surface of the photoreceptor is suitably rubbed in the presence of inorganic base fine particles, image flow is suppressed, and a good image can be obtained over a long period of time. I was able to. If S is too small, rubbing will be insufficient, and the effect of suppressing image flow may be reduced in part or as a whole. On the other hand, if it is too large, rubbing will be sufficient, but the relative speed difference between the developing sleeve and the photoconductor will become very large, or the cross-sectional area of the magnetic brush will become large, so that toner scattering, developer deterioration, In some cases, the photoreceptor was worn out. The peripheral speed Vdr of the photosensitive member is expressed as a positive number, and the peripheral speed Vsl of the developer carrying member is positive when moving in the same direction at a portion facing the photosensitive member, and negative when moving in the counter direction. Indicated by In this example, the speed is the same direction, that is, a positive speed.

  Vdr and Vsl can be controlled by a drive source of the image forming apparatus by transmitting drive from each or one of them to a predetermined speed ratio. The development nip h can be adjusted by the diameter of the development sleeve, the formation of a plurality of sleeves, the thickness of the developer to be conveyed, the shortest distance (development gap) between the development sleeve and the photoreceptor. The magnetic brush cross-sectional area m and the magnetic brush density a can be adjusted by the magnetic pole position, magnetic force density, etc. of the magnetic material contained in the developing sleeve. It can also be controlled by a developer carrier described later. The developing nip h is a state in which a magnetic brush made of a developer is formed, and the photosensitive member is observed at an area where the developing sleeve and the photosensitive member are opposed to each other and the arc length contacting the magnetic brush is observed. Asked. When there were a plurality of developing sleeves, the sum of the nips was used. The magnetic brush cross-sectional area m and the magnetic brush density a were determined by observing the shape of the magnetic brush at the position corresponding to the development nip using a laser microscope or the like in a state where the magnetic brush cross-sectional area m and the magnetic brush density a were not in contact with the photoreceptor. In this example, a laser microscope VK-8700 manufactured by Keyence Co., Ltd. is used, the objective lens magnification is 20 [times], and the height resolution is 0.1 [μm]. A total of 15 observations were made at three locations. From the observation results, the average value of the number of magnetic brushes per unit area was m, and the average value of the cross-sectional area of the magnetic brush at a height corresponding to the distance of contact with the photosensitive member was a.

Carrier The magnetic carrier according to the present invention is a magnetic carrier containing magnetic core particles and a resin, and is a metal oxide on the projected surface of a reflected electron image having an acceleration voltage of 2.0 kV, which is photographed by a scanning electron microscope. The area of the portion derived from is 0.5 area% or more and 10.0 area% or less with respect to the particle projected area of the magnetic carrier, and is derived from the metal oxide on the particle projected surface of the magnetic carrier. average area value portions, it is a feature at 0.45 [mu] m ² or more 1.40 .mu.m ² or less. When the magnetic carrier in the above range was used in the state where the inorganic base was present in the development nip, the image flow was suppressed, the wear of the developer and the photoreceptor was also suppressed, and a high-quality image was obtained over a long period of time.

In the magnetic carrier according to the present invention, the portion derived from the metal oxide of 6.672 μm ² or more is 10 area% or less with respect to the total area of the portion derived from the metal oxide on the projection plane. It is preferable. Furthermore, it is preferable that the part derived from the metal oxide of 2.780 μm ² or less is 60 area% or more with respect to the total area of the part derived from the metal oxide. When a magnetic carrier in these ranges was used, the flow suppression effect was further improved.

  The reason why the magnetic carrier of the present invention exhibits such an excellent effect is not clear, but the present inventors consider as follows.

  In the magnetic carrier of the present invention, a conductive metal oxide portion is optimally distributed on the surface of a magnetic carrier particle containing at least a conductive magnetic core particle and an insulating resin. Examples of the material of the magnetic core particles include metal oxide particles such as iron oxide powder and magnetite, or compound particles thereof such as ferrite.

  In the developing nip, since the developer carrying member is rotating, the contact points of the magnetic carrier particles forming the magnetic spikes with the photosensitive member 101 are also constantly changing. By making the area ratio at which these cores are exposed and the average area of the portions exposed in that range into a specific range, the metal oxide portion always has the above-mentioned inorganic base in the development nip. The surface can be rubbed suitably. As a result, the inorganic base that has contributed to the suppression of the deterioration of the photoreceptor described above is suitably agitated so that it can be easily removed from the surface of the photoreceptor, or scraping, supply of the next new inorganic base, and protection of the photoreceptor surface are suitable. It is thought that it can be maintained.

  When the area of the portion derived from the metal oxide is less than 0.5 area%, the flow suppressing effect is lowered. This is thought to be due to the lack of rubbing and stirring by the magnetic core made of a high hardness metal oxide. On the other hand, when the area is larger than 10.0 area%, the photoreceptor may be scratched or the like, or the toner charge amount may be reduced. This is presumably because the photoconductor or the inorganic base is mixed in a large amount due to excessive rubbing.

  In particular, when a combination of calcium carbonate and a magnetic carrier having a portion derived from a metal oxide of 0.5 area% or more and 10 area% or less is present, toner chargeability and scattering are extremely long-lasting. Was maintained well.

  Although the detailed mechanism is unknown, the combination of calcium carbonate and the above-mentioned magnetic carrier suppresses the spent of calcium carbonate on the magnetic carrier or the like, or the core exposure is suitably dispersed and the influence of adhesion hardly occurs. It is thought that it has become.

Moreover, when the average area value of the portion derived from the metal oxide was less than 0.45 μm ² , the flow suppressing effect was lowered. This is thought to be due to the lack of rubbing and stirring by the magnetic core made of a hard metal oxide. On the other hand, when it is larger than 1.40 μm ² , the effect on the flow may be partially reduced. This is thought to be due to the fact that the area per piece where the core is exposed becomes larger and the exposed portions become sparse, so that the flow suppression effect becomes non-uniform. As the average area value further increased, the photoreceptor was also worn.

When the portion derived from the metal oxide of 6.672 μm ² or more is 10 area% or less with respect to the total area of the portion derived from the metal oxide, wear of the photoreceptor and developer can be suppressed. Furthermore, contamination of the charging member is reduced. Most preferably, there is no portion derived from a metal oxide of 6.672 μm ² or more. By reducing the number of exposed portions of the metal oxide, a large number of exposed portions of the metal oxide exist, suppressing fine scratches (irregularities) on the surface of the photoconductor, and fine particles excessively cleaning the means. It is thought that it is possible to suppress slipping through. If the portion derived from a metal oxide of 6.672 μm ² or more exceeds 10 area%, the flow suppressing effect may be non-uniform.

When the portion derived from the metal oxide of 2.780 μm ² or less is 60 area% or more with respect to the total area of the portion derived from the metal oxide, flow recovery is improved and wear of the cleaning blade is reduced. To do. It is thought that the number of times the surface of the photoconductor is rubbed increases and the uniformity is improved because there are many objects with a small area where the metal oxide is exposed, that is, many small exposed portions are distributed. . The portion derived from a metal oxide of 2.780 μm ² or less is most preferably 100 area%.

The magnetic carrier preferably has a magnetization strength at 1000 / 4π (kA / m) of 30 (Am ² / kg) to 65 (Am ² / kg). When the magnetization intensity is 30 (Am ² / kg) or more and 65 (Am ² / kg) or less, the suppression of image flow when used at high speed is further improved, and the image density stability is improved.

  As described above, magnetic carriers are in contact with each other at points to form magnetic spikes. These magnetic spikes are formed by the magnetic lines of force of the magnetic substance contained in the developer carrying member. However, when the magnetization intensity of the magnetic carrier is lowered, each spike becomes low and thin or fine. As a result, the magnetic brush can rub the surface of the photoconductor in the development nip. In addition, since the number of magnetic spikes (density of magnetic spikes) per unit area on the photoreceptor surface increases and the number of rubbing per unit area on the photoreceptor surface increases, an inorganic base present in the development nip is suitable. It is thought that it was able to rub.

If it is 30 (Am ² / kg) or less, the developer may be scattered. On the other hand, if it is 65 (Am ² / kg) or more, the photoreceptor may be worn or the developer may be mechanically worn.

  As a method for producing these carriers, the carrier core particles can be produced and then coated on the surface thereof with a resin. As a specific production method, a known method can be used.

Examples of the method for producing the carrier core particles include the following methods.
First, the pulverized and mixed ferrite raw material is calcined in the air at a calcining temperature of 700 ° C. or higher and 1000 ° C. or lower for 0.5 hour or more and 5.0 hours or less to form a calcined ferrite. The calcined ferrite is finely pulverized with a pulverizer. In this case, the volume-based 50% particle size (D50) of the calcined ferrite finely pulverized product is preferably 0.5 μm or more and 5.0 μm or less.

  Water, binder, and magnetic core are added to the calcined ferrite product. For example, polyvinyl alcohol is used as the binder. When the carrier core particles are prepared as porous magnetic core particles, a void adjusting agent is added as necessary. Examples of the void adjusting agent include known foaming agents and resin fine particles.

The obtained ferrite slurry is dried and granulated using a spray dryer in a heated atmosphere of 100 ° C. or higher and 200 ° C. or lower. Next, the granulated product is calcined at 800 ° C. or more and 1400 ° C. or less for 1 hour or more and 24 hours or less.
When porous magnetic core particles are used as the magnetic core particles, the internal void volume can be adjusted by adjusting the firing temperature and firing time. Moreover, the specific resistance of the magnetic carrier core particles can be adjusted to a preferred range by controlling the firing atmosphere. For example, the specific resistance of the magnetic core particles can be lowered by lowering the oxygen concentration or reducing atmosphere (in the presence of hydrogen).

  After pulverizing the particles fired as described above, coarse particles and fine particles may be removed by classification or sieving as necessary.

The volume distribution reference 50% particle diameter (D50) of the magnetic core particles is more preferably 18.0 μm or more and 68.0 μm or less in order to prevent carrier adhesion to the image and suppression of roughness.

  The porous magnetic core particles may have a low physical strength depending on the internal void volume, and in order to increase the physical strength as the magnetic carrier particles, at least a part of the voids of the porous magnetic core particles may contain a resin. It is also preferable to perform filling. The amount of the resin to be filled is preferably 6% by mass or more and 25% by mass or less with respect to the porous magnetic core particles. If there is little variation in the resin content for each magnetic carrier particle, even if only part of the internal voids are filled or only the voids near the surface are filled, the internal voids are completely filled with resin. Also good.

  Although the specific filling method is not particularly limited, for example, a method of diluting the resin in a solvent and adding it to the voids of the porous magnetic core particles can be employed. The solvent used here may be any solvent that can dissolve the resin, and an organic solvent or water may be appropriately selected.

  The resin that fills the voids of the porous magnetic core particles is not particularly limited, and either a thermoplastic resin or a thermosetting resin may be used. When a resin having high affinity for the porous magnetic core particles is used, it is preferable because the surface of the porous magnetic core particles can be easily covered with the resin at the same time when the resin is filled in the voids of the porous magnetic core particles.

  As the resin to be filled, a known thermoplastic resin, thermosetting resin, or a resin obtained by modifying these resins may be used. Among these, silicone resins are preferable because they have high affinity for the porous magnetic core particles, can reduce the adhesion between the magnetic carrier particles and the toner, and improve developability. The amount of the resin solid content in the resin solution is preferably 1% by mass or more and 50% by mass or less.

  Even if the porous magnetic core particle is simply filled with a resin, it can be used as a magnetic carrier. In that case, in order to improve the charge imparting property to the toner, the resin solution may be filled with a charge control agent, a charge control resin, or the like in advance.

  In the magnetic carrier of the present invention, it is more preferable that the surface of the carrier core particle as described above is coated with a resin because the area and area distribution of the portion derived from the metal oxide can be precisely adjusted on the surface of the magnetic carrier particle. In addition, the surface is coated with resin from the viewpoint of controlling the releasability of the toner from the surface of the magnetic carrier particles, the contamination of the toner and external additives on the surface of the magnetic carrier particles, the ability to impart charge to the toner and the magnetic carrier resistance It is preferable to do.

  The method for coating the surface of the magnetic core particles with a resin is not particularly limited, and examples thereof include a coating method such as a dipping method, a spray method, a brush coating method, a dry method, and a fluidized bed. Among these, a dipping method capable of appropriately exposing the magnetic core particles to the surface is more preferable.

  The amount of the resin to be coated is preferably 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the magnetic core particles because the metal oxide portion can be appropriately exposed on the surface. .

  The resin to be coated can be used alone or in combination. The resin to be coated may be the same as or different from the resin used for filling, and may be a thermoplastic resin or a thermosetting resin. In addition, a curing agent or the like can be mixed with a thermoplastic resin and cured for use. It is more preferable to use a resin having high releasability.

  Further, the coating resin may contain conductive particles, charge controllable particles, a charge control agent, a charge control resin, various coupling agents, and the like for controlling the chargeability.

The magnetic carrier of the present invention has a volume distribution reference 50% particle size (D50) of 20.0 μm or more and 70.0 μm or less, which can suitably rub the surface of the photoreceptor on which the inorganic base is present and also adheres to the carrier. It can be suppressed and is preferable. Further, the toner spent is suppressed, and the toner spent can be stably used even for a long period of time.

The magnetic carrier of the present invention preferably has a magnetization strength at 1000 / 4π (kA / m) of 30 Am ² / kg or more and 65 Am ² / kg or less. Within this range, the developer spikes on the developer carrying member can be formed finely and densely, and the surface of the photoreceptor in the state where the inorganic base is present can be suitably rubbed, which is preferable. It is also preferable for improving dot reproducibility, preventing carrier adhesion, and preventing toner spent and obtaining a stable image.

The magnetic carrier of the present invention preferably has a true specific gravity of 3.2 g / cm ³ or more and 5.0 g / cm ³ or less in order to prevent toner spent and maintain a stable image over a long period of time. More preferably, it is 3.4 g / cm ³ or more and 4.2 g / cm ³ or less, which prevents carrier adhesion and is superior in durability.
The carrier characteristics according to the present invention were measured as follows.

<Area% of the portion derived from the metal oxide on the surface of the magnetic carrier particle>
The area% of the portion derived from the metal oxide on the surface of the magnetic carrier particle in the present invention can be obtained by observation of a reflected electron image by SEM and subsequent image processing (FIGS. 2 to 3). In SEM observation, it is known that the amount of reflected electrons emitted from a sample is larger as a heavy element. As in the carrier surface of the present invention, in the sample in which the metal oxide portion derived from the resin portion and the core is present, the metal oxide portion is bright (high brightness, white) and the resin portion is dark (low brightness, black) ) (See FIG. 2A), an image having a large contrast difference can be obtained.

  In this example, S-4800 (manufactured by Hitachi, Ltd.) was used as the SEM. The area% of the portion derived from the metal oxide is calculated from the image processing of an image mainly visualizing reflected electrons when the acceleration voltage is 2.0 kV. From the image obtained by SEM (FIG. 2-A), only the carrier portion is extracted (FIG. 2-B), and an image of the contrast difference between the resin portion and the metal oxide is obtained (FIG. 2-C). The projected area of the carrier and the area caused by the metal oxide are obtained from the image (FIG. 2-D), and the area value caused by the metal oxide and the area ratio to the projected area of the carrier are obtained by analysis.

Specifically, the carrier particles were fixed with a carbon tape on a sample stage for SEM observation in a single layer, and were observed under the following conditions without performing deposition with platinum. Observe after performing the flushing operation.
SignalName = SE (U, LA80),
AcceleratingVoltage = 2000Volt,
EmissionCurrent = 10000 nA,
Working Distance = 6000um,
LensMode = High,
Condencer1 = 5,
ScanSpeed = Slow4 (40 seconds),
Magnification = 600,
DataSize = 1280 × 960,
ColorMode = Grayscale,
In this example, the image is visualized at a magnification of 600. From the scale on the image, the length of 1 pixel is 0.1667 μm, and the area of 1 pixel is 0.0278 μm ² .

Subsequently, using the obtained projected image, the area% of the portion derived from the metal oxide was calculated for 50 magnetic carrier particles. Details of the method of selecting 50 magnetic carrier particles to be analyzed will be described later. Image processing software Image-Pro Plus 5.1J (manufactured by Media Cybernetics) was used for the area% of the portion derived from the metal oxide.
First, unnecessary portions such as character strings at the bottom of the obtained image were deleted and cut out to a size of 1280 × 895.
Next, the magnetic carrier particle part was extracted, and the size of the extracted magnetic carrier particle part was counted. Specifically, first, in order to extract the magnetic carrier particles to be analyzed, the magnetic carrier particles and the background portion are separated. Select “Measurement”-“Count / Size” of Image-Pro Plus 5.1J. In “Brightness range selection” of “Count / Size”, the brightness range was set to a range of 50 to 255, and the low-brightness carbon tape portion reflected in the background was excluded, and magnetic carrier particles were extracted. . When performing the extraction, select 4 connections in the “Count / Size” extraction option, enter a smoothness of 5, enter a check for fill in holes, and check for particles or other points on all boundaries (peripheries) of the image. Particles overlapping with particles were excluded from the calculation. Next, in the “count / size” measurement item, an area and a ferret diameter (average) were selected, and the area selection range was set to a minimum of 300 pixels and a maximum of 10000000 pixels. Further, the selection range is set so that the ferret diameter (average) is within a range of ± 25% of the measured value of the volume distribution reference 50% particle diameter (D50) of the magnetic carrier, which will be described later, and the magnetic carrier particles subjected to image analysis are selected. Extracted. The size of the portion derived from the extracted magnetic carrier particles (number of pixels) (ja), the sum of each extracted portion (Σja = Ja), and the number of extracted portions (Jc) were obtained. The same operation was repeated for the projected magnetic carrier particle image of another field until the number Jc of the extracted carrier particles reached Jc = 50.

Next, a portion derived from the metal oxide was extracted from the selected particles. In “Brightness range selection” of “Count / Size” of Image-Pro Plus 5.1J, the brightness range was set to a range of 140 to 255, and a portion with high brightness on the carrier particles was extracted. The area selection range was set to a minimum of 10 pixels and a maximum of 10000 pixels, and a portion derived from the metal oxide on the surface of the magnetic carrier particles was extracted. Further, similarly to the extraction of the magnetic carrier part, particles located on the outer periphery of the image and those deviating from the range of ± 25% diameter of the measured value of 50% particle diameter (D50) were excluded from the calculation. The sum (Ma = Σma) of the size (pixel number) (ma) of the extracted portion derived from the metal oxide and the above Ja were used for calculation according to the following equation.
Area% derived from metal oxide = Ma / Ja × 100 (Equation 8)

<Area distribution with respect to the total area of the portion derived from the metal oxide>
The area distribution with respect to the total area of the portion derived from the metal oxide can be obtained by observation of reflected electron images with a scanning electron microscope, image processing, and subsequent statistical processing (FIG. 3). In the same manner as obtaining the area% of the portion derived from the metal oxide, the magnetic carrier was observed, and the portion derived from the metal oxide in the magnetic carrier was extracted from the image. Portions derived from the extracted metal oxide were distributed in channels of size 20 pixels (FIG. 3-A). The area of 1 pixel is 0.0278 μm ² and converted into an area (FIG. 3-B), and the ratio of the distribution of 6.672 μm ² or more and 2.780 μm ² or less with respect to the total area of the portion derived from the metal oxide. The ratio of distribution was calculated.

<Measurement Method of Volume Distribution Standard 50% Particle Size (D50) of Magnetic Carrier Particles and Magnetic Core Particles>
The particle size distribution was measured with a laser diffraction / scattering particle size distribution measuring apparatus “Microtrack MT3300EX” (manufactured by Nikkiso Co., Ltd.).
The volume distribution standard 50% particle size (D50) of the magnetic carrier particles and the magnetic core particles was measured by mounting a sample feeder “One-shot dry sample conditioner Turbotrac” (manufactured by Nikkiso Co., Ltd.) for dry measurement. . As the supply conditions of Turbotrac, a dust collector was used as a vacuum source, the air volume was about 33 liters / sec, and the pressure was about 17 kPa. Control is automatically performed on software. For the particle size, a 50% particle size (D50), which is a cumulative value based on volume, is obtained. Control and analysis are performed using attached software (version 10.3.3-202D). The measurement conditions were SetZero time 10 seconds, measurement time 10 seconds, number of measurements once, particle refractive index 1.81, particle shape non-spherical, measurement upper limit 1408 μm, measurement lower limit 0.243 μm. The measurement was performed in a normal temperature and normal humidity (23 ° C., 50% RH) environment.

Toner As the toner, a known toner containing at least toner particles and an external additive can be used. The toner particles appropriately contain known toner materials such as a binder resin, a colorant, and waxes.
In addition, toner particles of a known production method such as pulverized toner and chemical toner can be used, but it is more preferable that the toner particles have the following characteristics.

  The toner particles preferably have a mass average particle diameter (D4) of 3 to 12 [μm] from the viewpoints of high image quality and cleanability. From the viewpoint of image quality such as transferability, the average circularity of the toner particles is preferably 0.930 or more. On the other hand, when it is 0.980 or less, cleaning is easy. In addition, each toner particle is easily subjected to a rotational load in a different direction, and the toner particles are easily diffused in the cleaning unit. As the toner diffuses, the uniformity of the coating or removal of the above-mentioned inorganic base on the surface of the photoreceptor is preferably improved.

  By using a toner having an average circularity in the above range in combination with the magnetic carrier of the present invention, the fluidity as a developer can be appropriately controlled. As a result, the transportability of the two-component developer on the developer carrying member is improved, and the formation of the developer spikes is likely to be dense and uniform. Further, the rising property of the toner charge amount is improved, and even when the toner is replenished to the developer, the toner is quickly charged, and fogging at the time of replenishment after long-term use can be suppressed.

Known hydrocarbon waxes, colorants, and charge control agents contained in the toner can be used at known contents.

As a method for producing toner particles, any of suspension granulation method, suspension polymerization method, dispersion polymerization method, emulsion polymerization method, emulsion aggregation method, pulverization method and the like may be used.

  If necessary, fine particles can be externally added according to applications such as a fluidity improver and a release agent. Known types of fine particles to be externally added (referred to as external additives), amounts, and external addition methods can be used.

  As the spacer particles for improving the releasability, it is preferable to contain inorganic particles having at least one maximum value of the particle size distribution in the range of 50 nm or more and 300 nm or less based on the number distribution. In order to more effectively suppress the detachment of the inorganic particles from the toner while functioning as the spacer particles, it is more preferable that the inorganic particles having at least one maximum value in the range of 80 nm to 150 nm are externally added.

  As the lubricant for improving fluidity, known lubricants can be used, and inorganic fine powders such as silica, titanium oxide, and aluminum oxide are preferable. These inorganic fine powders preferably have at least one maximum value in the range of 20 nm to 50 nm in the particle size distribution based on the number distribution.

  The total content of the external additives is preferably 0.3 parts by mass or more and 5.0 parts by mass or less, and 0.8 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. It is more preferable. These external additives are preferably hydrophobized with a known hydrophobizing agent or the like. When the inorganic base is used by externally adding to the toner particles, it can be externally added by a known external addition method using a known mixer such as a Henschel mixer, in the same manner as the above various fine particles. . It is preferable to add an inorganic base externally to the toner particles, since these particles are also promoted to diffuse with the developing means, and the uniformity in the longitudinal direction is improved when supplied to the surface of the photoreceptor. In particular, since the two-component development method is used, the uniformity in the longitudinal direction is further improved by stirring with a magnetic carrier as compared with the one-component development method. That is, even if the toner amount is localized in the longitudinal direction, it is excellent in returning to the current state. Accordingly, the photosensitive member surface is uniformly contacted and supplied regardless of the image ratio or the like. Further, it is not necessary to provide a separate member for supply, which is advantageous for downsizing.

  Various characteristics of the toner of the present invention were measured as follows.

<Measurement of average circularity of toner>
The average circularity of the toner was measured with a flow type particle image measuring device “FPIA-3000 type” (manufactured by Sysmex Corporation).
Specifically, using a flow-type particle image analyzer that has been issued a calibration certificate issued by Sysmex Corporation, the analysis particle diameter is limited to an equivalent circle diameter of 1.985 μm or more and less than 39.69 μm. Measurements were taken under the measurement and analysis conditions when the calibration certificate was received.

<Measurement of weight average particle diameter (D4) of toner>
The weight average particle diameter (D4) of the toner can be measured by a known method. In this example, the precision particle size distribution measuring device “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter) and the dedicated software “Beckman Coulter” for setting measurement conditions and analyzing measurement data are included. Using a Multisizer 3 Version 3.51 (manufactured by Beckman Coulter), measurement was performed with 25,000 effective measurement channels, and measurement data was analyzed and calculated.

-Two-component developer A toner and a magnetic carrier are mixed to obtain a two-component developer. The mixing ratio may be in a known range, but the toner is preferably 2 parts by mass or more and 35 parts by mass or less, and preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the magnetic carrier. By setting the amount within the above range, it is preferable to balance the suitable rubbing of the photoreceptor with the developer spike, the developability such as imparting electrification to the toner, and the reduction of toner scattering.

-Photoconductor The well-known photoconductor can be used as the photoconductor 101. However, if the amount of wear is small, the surface shape is maintained over a long period of time, and there is little variation in the durability of slipping through the various inorganic fine particles. This is preferable.

  FIG. 5 is a model diagram of the layer structure of the photoreceptor 101 in this example. In this photoreceptor 101, a charge generation layer 101d and a charge transport layer 101e are provided in this order as a photosensitive layer on a support 101a, and a protective layer 101f with a lower wear rate (high mechanical strength) is provided on the outermost surface. It is set in. Further, a binder layer 101b and an undercoat layer 101c for the purpose of preventing interference fringes may be provided between the support 101a and the charge generation layer 101d. In addition, a well-known thing can be used for the support body 101a, the binder layer 101b, the undercoat layer 101c, and the charge generation layer 101d.

  The binder layer 101b is used to improve the adhesion of the photosensitive layer, improve the coating property, protect the support, cover defects of the support 101a, improve the charge injection from the support 101a, and protect against electrical breakdown of the photosensitive layer. Formed for.

  The thickness of the charge transport layer 101e is preferably 5 to 40 μm, particularly preferably in the range of 7 to 30 μm.

  Further, by forming the protective layer 101f on the charge transport layer 1e, it is possible to produce the photoreceptors 101 having different wear rates.

  The wear amount can be controlled by the system of the image forming apparatus, such as cleaning setting, setting of charging means, use of the above-described lubricant, and the like. Further, when a photoconductor excellent in wear resistance is used, the surface shape is more suitably maintained and effective even in the same system.

  As a photoreceptor excellent in abrasion resistance, an organic photoreceptor (referred to as OCL-OPC) having a curable surface protective layer cured by a known electron beam, light, heat or the like can be preferably used.

  The photoreceptor 101 preferably has elasticity. By having elasticity, it is possible to bend slightly at the above-described developing nip and increase the rubbing area, and to prevent the photoreceptor 101 and the carrier from being worn.

  The elastic deformation rate Wu is preferably 40% or more and 60% or less. In this range, the image flow was suitably suppressed, the wear of the photoconductor and the carrier was suppressed, and high image quality could be maintained for a long time. When Wu is less than 40%, the flow suppressing effect may be reduced, or the surface of 101 or the carrier may be worn. On the other hand, when Wu exceeds 60%, the surface of the photoconductor may be damaged due to the magnetic ears being excessively engulfed in the photoconductor at the development nip. In addition, the image quality may be deteriorated due to the inhibition of the movement of the magnetic spikes according to the developer carrier.

  In the case where the surface layer is composed of a curable resin, the method includes, for example, that the charge transport layer is composed of a curable resin, and the second charge transport layer or the protective layer is formed on the charge transport layer. Examples of the layer include forming a curable resin layer. The properties required for the curable resin layer are both the strength of the film and the charge transport capability, and are generally composed of a charge transport material and a polymerized or crosslinkable monomer or oligomer.

  In the case of the charge transport layer, the average thickness of the cured layer is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 35 μm or less. In the case of the second charge transport layer or protective layer, the thickness is preferably 0.1 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less.

〔式中、Ａは正孔輸送性基を示す。Ｐ^１及びＰ^２は連鎖重合性官能基を示す。Ｐ^１とＰ^２は同一でも異なってもよい。Ｚは置換基を有してもよい有機残基を示す。ａ、ｂ及びｄは０又は１以上の整数を示し、ａ＋ｂ×ｄは２以上の整数を示す。また、ａが２以上の場合Ｐ^１は同一でも異なってもよく、ｄが２以上の場合Ｐ^２は同一でも異なってもよく、またｂが２以上の場合、Ｚ及びＰ^２は同一でも異なってもよい。〕 In order to obtain an electrophotographic photosensitive member having the elastic deformation rate Wu in the above range, the surface layer of the electrophotographic photosensitive member is cured by polymerization (polymerization accompanied by crosslinking) with a hole transporting compound having a chain polymerizable functional group. It is preferable to form it. In particular, it is effective to form a hole transporting compound having two or more chain polymerizable functional groups in the same molecule as shown in the following formula (Chemical Formula 1) by curing polymerization.

[Wherein, A represents a hole transporting group. P ¹ and ^{P 2} represents a chain polymerizable functional group. P ¹ and P ² may be the same or different. Z represents an organic residue which may have a substituent. a, b, and d represent 0 or an integer of 1 or more, and a + b × d represents an integer of 2 or more. When a is 2 or more, P ¹ may be the same or different. When d is 2 or more, P ² may be the same or different. When b is 2 or more, Z and P ² are the same or different. May be. ]

  By including at least one of fluorine atom-containing resin, carbon fluoride, and polyolefin resin as the lubricant 101g in the protective layer 101f, the slipperiness and water repellency of the surface of the photoreceptor can be improved. Thereby, the wear and shape change of the protective layer 101f can be further suppressed. Further, it is possible to prevent deterioration of transfer characteristics and slipperiness due to chemical deterioration of the protective layer 101f due to charging, development, transfer, etc. during repeated use, and further deterioration of electrical characteristics such as sensitivity reduction and potential reduction. Particularly preferable results are obtained when the fluorine-containing resin is used.

  The ratio of the lubricant 101g contained in the protective layer 101f is preferably 1 to 70 [%], more preferably 5 to 50 [%] with respect to the total weight of the layer to be the protective layer 101f. When the amount of the lubricant 101g is more than 70%, the mechanical strength of the layer serving as the protective layer 101f is likely to be lowered, and when the amount is less than 1%, the water repellency and slipperiness of the layer serving as the protective layer 101f are not sufficient. There is.

  It is also possible to contain a charge transport material in the protective layer 101f containing the cured product of the hole transport compound having the chain polymerizable group.

It is also preferable to control the surface shape of the photoreceptor 101. If the surface shape Rz is too large, the application / coating of the lubricant becomes non-uniform, and scraping or rubbing of the deteriorated lubricant by the cleaning blade, inorganic fine particles or cleaning brush tends to be non-uniform. There is a case. On the other hand, if Rz is too small, toner particles and external additives may adhere to the photoreceptor and filming and the like may easily occur. Further, the toner may be fixed, resulting in an image defect. The surface roughness Rz of the photosensitive member is preferably 0.1 to 1.0 [μm], although it depends on the configuration of the cleaning means and use conditions. The Rz is preferably in the above range from the beginning through endurance.
Also from the viewpoint of maintaining Rz, the elastic deformation rate Wu is preferably 40% or more and 60% or less.
The surface shape of the photoconductor 101 was adjusted by subjecting the surface of the photoconductor after film formation to a circumferential direction using a commercially available polishing tape.
The characteristics of the photoconductor according to the present invention were measured as follows.

<Universal hardness (Hu) and elastic deformation rate (Wu) of photoconductor>
The universal hardness value (Hu) and elastic deformation rate (Wu) of the surface of the electrophotographic photosensitive member are a microhardness measuring device Fischerscope H100V in accordance with ISO / FDIS14577 in an environment of an ambient temperature of 25 ° C. and a relative humidity of 50%. It is the value measured using (made by Fischer). Specifically, the measurement was performed according to the method described in paragraphs [0125] to [0130] of JP-A-2008-26864.

<Photoreceptor film thickness and wear amount>
The wear rate of the photoconductor 101 is measured by an eddy current film thickness meter (Fischerscope GROUNDEINHEIT MMS 3AM: manufactured by Ficher) before and after the endurance of the examples described later, and the wear amount per 100 k rotation is calculated. did.
The film thickness was measured for a total of 40 points, 8 points in the circumferential direction for each of 5 points in the longitudinal direction, and the average value thereof was taken as the film thickness.

<Surface shape of photosensitive member (Rz)>
The surface shape Rz of the photoreceptor 101 is Rz defined by JISB0601: 1994. The surface roughness was measured using a surface roughness measuring instrument (SURFPAK-SV4000S4: manufactured by Mitutoyo Corporation), measuring length 2.50 [mm], number of measurements 5 [times], height direction full scale 8 [μm], filters Gaussian, λc = 0.25, λs = 0.008, measurement speed = 0.1 [mm / sec], and measured by scanning in the longitudinal direction in JIS 1994 RLS_JIS mode.
The surface shape was measured for a total of 40 points of 8 points in the circumferential direction for each of the 5 points in the longitudinal direction, and the average value of these was used as the measurement value, and the average value of the measurement values of the 5 measurements was used as Rz.
The surface shape of the photoconductor 101 can be adjusted by a known method such as changing the polishing direction or blasting in addition to the circumferential polishing process as described above.

  Examples of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these examples of the present invention. Means may be used. Although not specifically shown, each unit such as a photosensitive member, a charging unit, a developing unit, and a cleaning blade may be individually installed in the image forming apparatus main body, or the photosensitive unit, the charging unit, and the developing unit. Two or more of the means and the cleaning means may be installed as an integrated cartridge.

[Examples of basic inorganic compound (inorganic base) production]
<Examples of calcium carbonate production>
Calcium carbonate can be produced by pulverizing naturally occurring limestone or the like or synthesizing it by a known chemical reaction. Synthetic calcium carbonate is easy to control particle size and particle size distribution.
In this example, calcium carbonate fine particles having a calcite crystal structure and a cubic particle shape were prepared. The reaction time and other conditions were controlled to produce fine particles with different particle sizes.
<Examples of zinc carbonate production>
The zinc carbonate fine particles can be produced by a known method. Carbon dioxide gas was introduced into a water slurry containing raw material zinc oxide to produce basic zinc carbonate, and fine particles were obtained through a pulverization step.
<Production example of magnesium carbonate>
Magnesium carbonate fine particles can be produced by a known method. Carbon dioxide gas was introduced into the water slurry containing the raw material magnesium oxide to produce basic magnesium carbonate, which was further pulverized to form fine particles.
<Production example of magnesium oxide>
Magnesium oxide fine particles can be produced by a known method.
<Surface treatment of inorganic base>
In order to control the degree of hydrophobicity of these inorganic bases, wet fatty acid treatment was performed on the surface of the inorganic bases with varying amounts of treatment. In this example, wet processing was performed with fatty acid, but known processing methods and processing agents can be used, and may be wet or dry.

  Table 1 below shows the number average particle diameter and the degree of hydrophobicity of the obtained various inorganic bases.

[Carrier production example]
<Example of manufacturing magnetic carrier>
Production example process 1 of core a1 (weighing / mixing process)
Fe ₂ O ₃ 61.1% by mass
MnCO ₃ 34.5% by mass
Mg (OH) ₂ 4.5% by mass
SrCO ₃ 0.9% by mass
The ferrite raw material was weighed so that This was pulverized and mixed for 2 hours in a dry ball mill using zirconia (φ10 mm) balls.
Process 2 (temporary firing process)
After pulverization and mixing, firing was performed at 950 ° C. for 2 hours in the air using a burner-type firing furnace to prepare calcined ferrite. The composition of the ferrite was as follows.
(MnO) _a (MgO) _b (SrO) _c (Fe ₂ O ₃ ) _d
In the above formula, a = 0.39, b = 0.10, c = 0.01, d = 0.50
Process 3 (Crushing process)
After crushing to about 0.5 mm with a crusher, 30 parts by mass of water is added to 100 parts by mass of calcined ferrite using alumina beads (φ1.0 mm) and pulverized with a wet bead mill for 2 hours to obtain a ferrite slurry. It was.
Process 4 (granulation process)
To the ferrite slurry, 9.0 parts by mass of polyvinyl alcohol was added as a binder with respect to 100 parts by mass of calcined ferrite, and granulated into spherical particles with a spray dryer (manufacturer: Okawara Chemical).
Process 5 (main firing process)
In order to control the firing atmosphere, firing was performed at 1100 ° C. for 4.5 hours in a nitrogen atmosphere (oxygen concentration less than 0.01% by volume) in an electric furnace.
Process 6 (screening process):
After the aggregated particles were crushed, coarse particles were removed by sieving with a sieve having an opening of 250 μm to obtain a core a1. Table 2 summarizes the physical properties of the core a1.

Production example of core a2 In the production example of core a1, in Step 1 (weighing / mixing step), ferrite raw materials are weighed as follows, and then pulverized and mixed in a dry ball mill using zirconia (φ10 mm) balls for 2 hours. did.
Fe ₂ O ₃ 68.0 mass%
MnCO ₃ 29.9% by mass
Mg (OH) ₂ 2.1% by mass
Further, a core a2 was produced in the same manner as in the production example of the core a1, except that in the step 5 (main firing step), the oxygen concentration was 0.02% by volume and the firing was performed at 1050 ° C. for 4 hours. Table 2 summarizes the physical properties of the core a2.

Example of producing core a3 In step 5 (main firing step) of the example of producing core a1, the core a3 was produced in the same manner as in the example of producing core a1, except that the oxygen concentration was 0.05% by volume and baked at 1050 ° C. for 4 hours. Manufactured. Table 2 summarizes the physical properties of the core a3.

Example of producing core a4 In step 5 (main firing step) of the example of producing core a1, the core a4 was produced in the same manner as in the example of producing core a1 except that the oxygen concentration was 0.2% by volume and baked at 1050 ° C. for 4 hours. Manufactured. Table 2 summarizes the physical properties of the core a4.

Example of producing core a5 In step 5 (main firing step) of the example of producing core a2, the core a5 was produced in the same manner as in the example of producing core a2, except that the oxygen concentration was 0.15% by volume and the product was fired at 1100 ° C. for 5 hours. Manufactured. Table 2 summarizes the physical properties of the core a5.

Example of producing core a6 In step 5 (main firing step) of the example of producing core a1, the core a6 was produced in the same manner as in the example of producing core a1 except that it was fired at 1050 ° C. for 4 hours at an oxygen concentration of 0.3% by volume. Manufactured. Table 2 summarizes the physical properties of the core a6.

Preparation of resin solution B Silicone varnish (SR2411 manufactured by Toray Dow Corning Co., Ltd., solid content concentration 20% by mass)
75.8 parts by mass γ-aminopropyltriethoxysilane 1.5 parts by mass Toluene 22.7 parts by mass The above was mixed to obtain a resin solution B (viscosity 1.2 × 10 ⁻⁴ m ² / sec).

Production Example of Magnetic Core Particle A1 100 parts by mass of core a1 is put in a universal stirring mixer (Dalton), heated to 82 ° C., and the resin corresponding to 16 parts by mass as a filling resin component with respect to 100 parts by mass of core a1. Solution B was added and stirred while evacuating the volatile organic solvent. Heating and stirring were continued at 82 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A1 (resin filling amount 15. 3 parts by mass).

Production Example of Magnetic Core Particle A2 100 parts by mass of core a2 is put into a universal stirring mixer (manufactured by Dalton), heated to 80 ° C., and a resin corresponding to 15 parts by mass as a filling resin component with respect to 100 parts by mass of core a2. Solution B was added and stirred while evacuating the volatile organic solvent. Heating and stirring were continued at 80 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A2 (resin filling amount of 14. 0 parts by mass).

Production Example of Magnetic Core Particle A3 100 parts by mass of core a3 is put into a universal stirring mixer (manufactured by Dalton), heated to 80 ° C., and a resin corresponding to 16 parts by mass as a filling resin component with respect to 100 parts by mass of core a3. Solution B was added and stirred while evacuating the volatile organic solvent. Heating and stirring were continued at 80 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A3 (resin filling amount 15. 1 part by mass).

Production Example of Magnetic Core Particle A4 100 parts by mass of core a4 is put into a universal stirring mixer (Dalton), heated to 82 ° C., and a resin corresponding to 12 parts by mass as a filling resin component with respect to 100 parts by mass of core a4. Solution B was added and stirred while evacuating the volatile organic solvent. Heating and stirring were continued at 82 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A4 (resin filling amount: 10. 5 parts by mass).

Production Example of Magnetic Core Particle A5 100 parts by mass of core a5 is put into a universal stirring mixer (manufactured by Dalton), heated to 80 ° C., and equivalent to 13 parts by mass as a filling resin component with respect to 100 parts by mass of magnetic core a5. Resin solution B was added, and the organic solvent which volatilized was stirred while exhausting. Heating and stirring were continued at 80 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A5 (resin filling amount: 12. 8 parts by mass).

Production Example of Core Particle A6 100 parts by mass of core a6 was put into a universal stirring mixer (manufactured by Dalton), heated to 80 ° C., and a resin solution corresponding to 13 parts by mass as a filling resin component with respect to 100 parts by mass of core a6. B was added and stirred while evacuating the volatile organic solvent. Heating and stirring were continued at 80 ° C. for 2 hours to remove the solvent. The obtained sample was transferred to a Julia mixer (manufactured by Deoksugaku Kosakusho), heat-treated at 200 ° C. for 2 hours in a nitrogen atmosphere, and classified with a mesh having an opening of 70 μm to obtain magnetic core particles A6 (resin filling amount: 13. 5 parts by mass).

<Example of production of magnetic carrier C1>
Preparation of resin solution C Silicone varnish (SR2411 manufactured by Toray Dow Corning Co., Ltd., solid content concentration 20% by mass)
69.4 parts by mass γ-aminopropyltriethoxysilane 2.8 parts by mass Toluene 27.8 parts by mass The above was mixed to obtain a resin solution D (viscosity 1.2 × 10 ⁻⁴ m ² / sec).

100 parts by mass of the magnetic core A1 was put into a Nauta mixer (manufactured by Hosokawa Micron Corporation), and adjusted to 70 ° C. under reduced pressure while stirring under the conditions of a screw rotation speed of 100 min ⁻¹ and a rotation speed of 3.5 min ⁻¹ . The resin solution C is diluted with toluene so that the solid content concentration becomes 10% by mass, and the resin solution is added so that the resin component C becomes 1.3 parts by mass as a coating resin component with respect to 100 parts by mass of the magnetic core A1. The solvent was removed and the coating operation was performed (first step coating). Thereafter, the temperature was raised to 180 ° C., stirring was continued for 2 hours, and then the temperature was lowered to 70 ° C. The sample was transferred to a universal stirring mixer (manufactured by Dalton), and the resin solution was added so that the coating resin component was 1.5 parts by mass with respect to 100 parts by mass of the magnetic core 1 as a raw material, Solvent removal and coating operations were performed over 2 hours (second stage coating). Furthermore, with respect to 100 parts by mass of the magnetic core 4 as a raw material, the resin solution is added using the resin solution C so that the coating resin component becomes 1.2 parts by mass. Similarly, the solvent removal and coating operation are performed over 2 hours. (3rd stage coat).

  The obtained sample was transferred to a Julia mixer (manufactured by Tokuju Kogakusha Co., Ltd.), heat-treated at a temperature of 180 ° C. for 4 hours in a nitrogen atmosphere, and then classified with a mesh having an opening of 70 μm to obtain a magnetic carrier C01. Table 3 shows the physical properties of the magnetic carrier C01 obtained.

<Production example of magnetic carriers C02 to C22>
With respect to the manufacturing example of the magnetic carrier C01, the resin coating treatment was performed in accordance with Table 3 below with respect to the amount of the first-stage coating to the third-stage resin solution C and the number of times of charging.
Table 4 shows the characteristics of the obtained magnetic carriers C01 to C22.

[Example of toner production]
<Example of production of resin A (hybrid resin)>
1.9 mol of styrene, 0.21 mol of 2-ethylhexyl acrylate, 0.15 mol of fumaric acid, 0.03 mol of dimer of α-methylstyrene, and 0.05 mol of dicumyl peroxide were placed in a dropping funnel. In addition, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane; 0 mol, 3.0 mol of terephthalic acid, 2.0 mol of trimellitic anhydride, 5.0 mol of fumaric acid and 0.2 g of dibutyltin oxide are placed in a 4-liter four-necked flask made of glass, a thermometer, a stirring rod, a condenser and nitrogen The introduction tube was installed and placed in a mantle heater. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and while stirring at a temperature of 145 ° C., the vinyl resin monomer, crosslinking agent and polymerization initiator were added from the dropping funnel over 5 hours. It was dripped. Next, the temperature was raised to 200 ° C. and reacted at 200 ° C. for 4.0 hours to obtain a hybrid resin (resin A). The molecular weight of this resin A by GPC was weight average molecular weight (Mw) 64000, number average molecular weight (Mn) 4500, and peak molecular weight (Mp) 7000.

<Manufacture of magenta master batch>
-Resin A (for masterbatch) 60 parts by mass-Magenta pigment (PigmentRed-57) 20 parts by mass-Magenta pigment (PigmentRed-122) 20 parts by mass The above materials were melt-kneaded with a kneader mixer to prepare a magenta masterbatch. .

<Example of toner production>
-Resin A 88.3 parts by mass-Refined paraffin wax (maximum endothermic peak: 70 ° C, Mw = 450, Mn = 32)
5.0 parts by mass / magenta masterbatch (colorant content 40% by mass) 19.5 parts by mass / aluminum compound of di-tertiary butylsalicylic acid (negative charge control agent)
0.9 parts by mass After the above formulation was mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a twin-screw kneader (PCM-30 type, Ikegai Iron Works Co., Ltd.) set at a temperature of 150 ° C. Kneaded). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely crushed material was finely pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Classification is performed using a particle design device (product name: Faculty) manufactured by Hosokawa Micron, and adjustment is performed so that the number of particles (small particles) having an equivalent circle diameter of 0.500 μm or more and less than 1.985 μm is 5% by number. And toner particles having a weight average particle diameter (D4) of 6.2 μm were obtained.
To 100 parts by mass of the obtained toner particles, 1.0 part by mass of hydrophobic silica fine particles having a primary average particle diameter of 16 nm surface-treated with 20% by mass of hexamethyldisilazane are added, and a Henschel mixer (FM-75 type, Mitsui Miike) is added. A toner was obtained by mixing and externally adding with a Kako Koki Co., Ltd.
When the inorganic base was added externally to the toner particles, the external addition treatment was performed under the above conditions together with the above hydrophobic silica.

[Developer production example]
To 92 parts by mass of the magnetic carrier C01, 8 parts by mass of toner was added and shaken for 10 minutes by a V-type mixer to prepare a two-component developer.

[Photosensitive body production example]
[Underlying Photoconductor Production Example]
As the support 101a, an aluminum cylinder for iR C3580 (hereinafter referred to as φ30 cylinder or simply referred to as φ30) and an aluminum cylinder for imagePRESS C7000VP (hereinafter referred to as φ84 cylinder or simply referred to as φ84) are manufactured by cutting, and degreasing cleaning is performed. gave.

  60 parts by mass of titanium oxide powder (trade name: Kronos ECT-62, manufactured by Titanium Industry Co., Ltd.) having a coating film of tin oxide doped with antimony, titanium oxide powder (trade name: titone SR-1T, 堺Chemical Co., Ltd.) 60 parts by mass, resol type phenol resin (trade name: Phenolite J-325, Dainippon Ink & Chemicals, Inc., solid content 70%) 70 parts by mass, 2-methoxy-1-propanol A solution consisting of 50 parts by mass and 50 parts by mass of methanol was dispersed with a ball mill for about 20 hours. The average particle size of the filler contained in this dispersion was 0.25 μm. The dispersion prepared in this manner was applied on the aluminum cylinder by the dipping method, and was heated and dried for 48 minutes in a hot air drier adjusted to 150 ° C. to form a conductive layer having a thickness of 15 μm. .

  Next, 10 parts by mass of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) and 30 parts by mass of methoxymethylated nylon resin (trade name: Toresin EF30T, manufactured by Teikoku Chemical Industry Co., Ltd.) were added to methanol 500. A solution dissolved in a mixed solution of parts by mass and 250 parts by mass of butanol is dip-coated on the conductive layer, put into a hot air dryer adjusted to 100 ° C. for 22 minutes, and dried by heating to obtain a film thickness of 0. A 45 μm undercoat layer 101c was formed.

  Next, 4 parts by mass of a crystalline hydroxygallium phthalocyanine crystal having strong peaks at 7.4 ° and 28.2 ° of the Bragg angle (2θ ± 0.2 °) in the CuKα-ray diffraction spectrum, polyvinyl butyral resin (trade name) : Esreck BX-1, Sekisui Chemical Co., Ltd.) 2 parts by mass and a mixed solution consisting of 90 parts by mass of cyclohexanone was dispersed for 10 hours with a sand mill using glass beads having a diameter of 1 mm, and then 110 parts by mass of ethyl acetate was added. In addition, a charge generation layer coating solution was prepared. This coating solution was dip-coated on the undercoat layer, put into a hot air dryer adjusted to 80 ° C. for 22 minutes, and dried by heating to form a charge generation layer 101d having a thickness of 0.17 μm.

及びビスフェノールＺ型ポリカーボネート樹脂（商品名：ユーピロンＺ４００、三菱エンジニアリングプラスティックス（株）製）５０質量部を、モノクロロベンゼン３２０質量部及びジメトキシメタン５０質量部に溶解して第１の電荷輸送層用塗布液を調製した。この第１の電荷輸送層用塗工液を、上記電荷発生層上に浸漬塗布し、１００℃に調整された熱風乾燥機中に４０分間投入して加熱乾燥し、膜厚が２０μｍの電荷輸送層１０１ｅを形成した。得られた感光体を下地感光体とした。
上述のφ３０、及びφ８４の下地感光体に、下記に示す表面保護層１０１ｆを設け、感光体Ｐ０１を作製した。 Next, 35 parts by mass of a triarylamine compound represented by the following structural formula (Formula 2)

And 50 parts by mass of bisphenol Z-type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) are dissolved in 320 parts by mass of monochlorobenzene and 50 parts by mass of dimethoxymethane, and applied to the first charge transport layer. A liquid was prepared. This first charge transport layer coating solution is dip-coated on the charge generation layer, put into a hot air drier adjusted to 100 ° C. for 40 minutes, and dried by heating to charge transport having a thickness of 20 μm. Layer 101e was formed. The obtained photoreceptor was used as a base photoreceptor.
A surface protective layer 101f shown below was provided on the above-described base photoconductors of φ30 and φ84 to prepare a photoconductor P01.

[Photoreceptor Production Example 1 (P01)]
The following raw materials were mixed and dissolved as a dispersant.
Fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.)
0.15 parts by mass 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd.) 35 parts by mass 1-propanol 35 parts by mass Lubricant tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.)
Three parts by mass were added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 600 kgf / cm ² with a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA).

This was subjected to pressure filtration with a 10 μm polytetrafluoroethylene (PTFE) membrane filter to prepare a lubricant dispersion.
To this lubricant dispersion is added 27 parts by mass of an acrylic resin D27 having a hole transporting compound represented by the following structural formula (Chemical Formula 3), pressure filtration is performed with a PTFE 5 μm membrane filter, and coating for a surface protective layer is performed. A liquid was prepared.

This coating solution was applied to the above-mentioned underlying photoconductor so as to have a thickness of 5 μm. Thereafter, an electron beam was irradiated in nitrogen under the conditions of an acceleration voltage of 150 kV and a dose of 1.4 × 10 ⁴ Gy. Subsequently, a heat treatment was performed for 90 seconds under the condition that the temperature of the electrophotographic photosensitive member was 120 ° C. The oxygen concentration at this time was 10 ppm. Further, the electrophotographic photosensitive member was heat-treated in a hot air dryer adjusted to 110 ° C. in the atmosphere for 20 minutes to form a cured surface protective layer having a thickness of 5 μm. Furthermore, the surface roughening process was performed using the commercially available silicon carbide wrapping tape (# 3000). In this example, the above wrapping tape was driven by an elastic backup roller with a relative speed difference in the same direction as the photoreceptor. While the backup roller was in contact with the photoconductor, it was driven for 150 seconds to perform a surface roughening process, and photoconductors P01 with φ84 and φ30 were obtained.

The electrophotographic photoreceptor P01 produced by the above method was left for 24 hours in an environment having an ambient temperature of 23 ° C. and a relative humidity of 50%, and then the elastic deformation rate and universal hardness were measured. As a result, the photoreceptors P01 of either φ30 or φ84 had an elastic deformation rate value of 48%, a universal hardness value of 197 N / mm ² , and a surface shape Rz of 0.31 μm. The results are shown in Table 5.

[Photoreceptor Production Example 2 (P02)]
In Photoconductor Production Example 1, a surface protective layer was prepared in the same manner as in Photoconductor Production Example 1 except that the surface protective layer was applied with a thickness of 8 μm by the dip coating method.

[Photoreceptor Production Example 3 (P03)]
In Photoconductor Production Example 1, the surface protective layer was applied to a thickness of 5 μm by an immersion method with 20 parts by mass of the resin D to be added. Further, the electron beam was irradiated under the conditions of an electron beam irradiation condition of an acceleration voltage of 130 kV and a dose of 1.0 × 10 ⁴ Gy. Subsequently, heat treatment was performed for 150 seconds under the condition that the temperature of the electrophotographic photosensitive member was 120 ° C. Thereafter, heat treatment was performed for 20 minutes in a hot air dryer adjusted to 110 ° C. in the air.

[Photosensitive member production example 4 (P04)]
In Photoconductor Production Example 3, the surface protective layer was applied to a thickness of 5 μm by an immersion method with 20 parts by mass of the resin D to be added. A photoconductor P04 was prepared in the same manner as in Photoconductor Production Example 3 except that the electron beam irradiation conditions were an acceleration voltage of 140 kV and a dose of 1.2 × 10 ⁴ Gy.

[Photoreceptor Production Example 5 (P05)]
In Photoconductor Production Example 1, a surface protective layer having a thickness of 5 μm was applied by a coating method with 40 parts by mass of the resin D to be added. A photoconductor P05 was prepared in the same manner as in Photoconductor Production Example 1 except that the electron beam irradiation conditions were an acceleration voltage of 150 kV and a dose of 1.4 × 10 ⁴ Gy.

[Photoreceptor Production Example 6 (P06)]
Photoconductor Production Example 5 except that the electron beam irradiation conditions were an acceleration voltage of 150 kV and a dose of 1.1 × 10 ⁴ Gy, and the heat treatment after the electron beam irradiation was carried out at 110 ° C. for 180 seconds in Photoconductor Production Example 5. A photoconductor P06 was prepared in the same manner as described above.

  In each of Photoconductor Production Examples 2 to 6 (P02 to P06), φ30 and φ84 were prepared. The surface roughening treatment was performed in the same manner as in Photosensitive Member Production Example 1, and Rz was in the range of 0.30 ± 0.05 μm in all cases. As a result of measuring the elastic deformation rate Wu and universal hardness Hu of these photoconductors, equivalent photoconductors were obtained at φ30 and φ84. Table 5 shows the measurement results.

[Evaluation equipment]
As an image forming apparatus for φ84 evaluation, Canon digital commercial printing printer imagePRESSSC7000VP was modified as follows (φ84 evaluation machine).
First, the driving speed of the photosensitive member was made variable. Needless to say, the speed of each means such as paper feeding, paper discharge, transfer, fixing, exposure, and the amount of light are synchronized with the photosensitive member driving speed.
The developing means was made such that the driving speed of the developer carrying member was variable, the shortest distance (developing gap) between the developing sleeve and the photosensitive member was variable, and the number of developing sleeves could be used from 1 to 3. A plurality of developing sleeves having different outer diameters, different magnetic pole patterns and different magnetic flux densities were prepared.
Further, the charging means was changed from the scorotron to a contact type charging roller for iRC5185 manufactured by Canon. The power supply for the charging means was changed so that the AC bias can be superimposed on the DC bias. The frequency and discharge current were variable.
The cleaning blade 107 was made of urethane rubber having a rubber hardness of 70 °, a 100% modulus of 3450 kN / m ² , and an elongation at break of 320%. The thickness T is 2 mm, the plate-shaped cleaning blade is set to a free length L of 8 mm, and the contact pressure to the photosensitive member 101 by the spring 107S = 24.5 N / m (25 g / cm), and the set angle θ = 24 °. Abutted.
A supply brush 108 was provided near the downstream side of the cleaning means in the direction of travel of the photoreceptor surface. The brush was driven at a relative speed of 130% in the same direction as the photosensitive pair at the portion facing the photoconductor. Further, flicker 111 for removing transfer residual toner and the like was added. The position of the flicker 111 may be adjusted by adjusting the setting conditions such as the direction and position according to the driving direction and speed of the supply brush 108.
The supply brush 108 is formed in a roll brush shape having a diameter of 16 mm by weaving conductive fibers on a base fabric and winding the fiber around a core metal having a diameter of 6 mm. A conductive fiber made of acrylic with a thickness of 0.67Tex (6 denier) is used, and the fiber is implanted in a base fabric with a W weave so that the fiber density is 100,000 / inch ² and formed into a sheet. The wire is wound so as to ensure conductivity with the cored bar. The resistance of the brush was 6 × 10 ² Ω · cm. The contact amount with respect to the photosensitive member 1 is 1 mm and the contact width is 7 mm.
Further, a solidified inorganic base obtained by pressure-molding an inorganic base was prepared, and it was brought into pressure contact with the supply brush as required so that it could be applied and supplied to the surface of the photoreceptor with the supply brush.

As an image forming apparatus for φ30 evaluation, a Canon color complex machine iR C3580 was modified as follows (φ30 evaluation machine).
The drive speed of the photosensitive member is variable, and the transfer, paper feed, paper discharge, and fixing drive speeds, the speed of the latent image exposure means, and the exposure amount are synchronized with this.
A plurality of developing means having different driving speeds and different outer diameters of the sleeve and magnetic bodies included in the sleeve were prepared. Also, different developing sleeves having one to two were prepared. The charging bias power supply can be changed in frequency and applied bias.
The cleaning blade was made of urethane rubber having a rubber hardness of 70 °, a 100% modulus of 3450 kN / m ² , and an elongation at break of 320%. With a thickness T of 2 mm, a plate-shaped cleaning blade, a free length L of 9 mm, and a spring 107S, the contact pressure to the photoreceptor 101 = 24.5 N / m (25 g / cm), and a set angle θ = 23 °. Abutted.

  In any of the evaluation apparatuses described above, the bias applied to the charging roller is such that the discharge current is 50 μA, and the surface potential (Vd) of the photosensitive member at the position facing the developing means when the latent image is not exposed. The absolute value of was adjusted to 600V. The latent image signal exposure was adjusted so that the absolute value of the latent image exposure irradiation portion potential (Vl) was 150V. Further, the developing bias and the transfer bias were appropriately adjusted according to the speed of the photoreceptor, the type of developer, and the like.

  An image forming apparatus as shown in FIG. 1 was prepared by using a remodeling machine and putting the developer in the developing unit at the cyan position.

[Examples 01 and 02]
Using the above-described φ30 evaluation apparatus, inorganic base carrier C03 and photoconductor P02 were used as the toner described above.
The surface speed Vdr of the developing sleeve photosensitive member was 300 mm / sec. The developing sleeve drive speed Vsl was 450 mm / sec. The cross-sectional area m of the magnetic brush was 0.1 mm ² / line, the magnetic brush density a was 4 / mm ² , and the development nip h was 7 mm. The cleaning brush 108 was removed.

  In Example 01, 0.3 parts by mass and 0.2 parts by mass of E03 and E08 as inorganic bases were externally added to the toner, respectively. In Example 02, 0.5 parts by mass and 0.5 parts by mass of E03 and E08, respectively, were added to the toner.

  Tables 6 and 7 show the conditions of the image forming apparatus. In addition, the symbols of inorganic base α and inorganic base β in the table are given for convenience. When an inorganic base is used alone, all are described in the column of the inorganic base α, and when a plurality of inorganic bases are used, the lower hydrophobicity is α and the higher is β.

  In the durability test, a belt image long in the longitudinal direction of the photoreceptor was formed. Images with the image ratio shifted to 3 levels of 3%, 5%, and 10% in the longitudinal direction were formed.

  Under normal temperature / humidity (23 ° C / 50% RH: hereinafter referred to as N / N) environment, an image with an image duty of 3, 5, 10% as shown in FIG. Printing was performed for 10 hours / day, and durability for 100,000 sheets was performed. Next, in a high temperature / high humidity (30 ° C./80% RH: hereinafter referred to as H / H) environment, and further in a low temperature / low humidity (15 ° C./10% RH: hereinafter referred to as L / L) environment, N / Similar to the N environment, 1 million sheets each, and a total of 300,000 durability tests were conducted. In each durability test, the power supply was completely turned off at night.

In each environment, an image for evaluation was formed in the initial stage, in the morning and last.
As evaluation images, 1-dot 1-space halftone image (denoted as 1D1S), 5 mm-interval grid image, 1D1S, 1-dot 2-space halftone image (denoted as 1D2S), solid, white, and first half are A two-tone image with a solid second half, a 17-tone image, and 1D1S were formed again in this order.
In the durability test in each of the above environments, after image evaluation, wear measurement of the edge portion of the cleaning blade, measurement of photoconductor wear, and contamination of the charging roller were evaluated.
Each evaluation item and evaluation criteria are as follows.
In the evaluation criteria, A to C are good, D is no problem in practical use, and E is the same level as before or may be insufficient in characteristics.

・ Image flow Evaluation was made by comparing images formed in the morning.
A: No image flow B: When the 1D1S and 1D2S images are observed at 25 to 50 times, the dots are crushed and blurred. C: One of the 17 gradation highlight areas, 1D1S, and 1D2S. Although the image irregularity of the drum cycle is visible, it can be resolved by image formation within 5 sheets at A4.
D: In the highlight area of 17 gradations, in any two or more of 1D1S, 1D2S, slight image irregularities of the photosensitive member period can be seen, but in A4, the image formation is eliminated within 5 sheets.
E: Other than the above. There may be problems with the same level or characteristics as before.

-Slip-through Mainly evaluated from visual evaluation of ruled line, two-tone, and half-tone images, and the photoreceptor surface observation results. A: No image slip-through. The surface of the photoconductor is also clean. B: No slip on the image. There is no toner contamination on the back side of the cleaning blade (downstream in the direction of travel of the photoconductor), so that the surface of the photoconductor can be detected by taping.
C: No slipping on the image. There is toner contamination on the back side of the cleaning blade (downstream in the direction of travel of the photoconductor). D: The image is slipped on the photoconductor but not on the image. E: The image is slipped off.

Filming / toner fixation Evaluation was performed from halftone, solid, white, 17-gradation images and the corresponding photoreceptor surface observation results.
A: Neither filming nor toner fixing on the image. The surface of the photoconductor is also clean. B: Local deposits are seen on the photoconductor, but there is no filming or toner fixation on the image. C: Local toner fixation is seen on the photoconductor, but on the image. Neither filming nor toner fixing D: There are deposits in the medium to wide range on the photoreceptor, but there is no filming on the image E: Image defect due to filming on the image or toner fixing

-Wear of the cleaning blade The cleaning blade after the durability test was observed from the direction of the visual field 107a107b, and the depth Dm and width Wm of the chipping or chipping were obtained and evaluated from the product of D and W. The D and W are defined as shown in FIG.
A: DW is 75 μm ² or less B: DW is more than 75 150 μm ² or less C: DW is more than 150 225 μm ² or less D: DW is more than 225 300 μm ² or less E: DW is more than 300 μm ²

-Wear of photoconductor From the measurement of the film thickness of the photoconductor before and after the durability test, the amount of wear [μm / 100 krot] per 100,000 rotations of the photoconductor was calculated. Further, the surface roughness Rzlast [μm] after the durability test was measured. As the maximum value of Rz through the durability test, the larger value of Rzini and Rzlast was displayed as large Rz.
A: The wear of the photoconductor is very small, and the surface shape is extremely small.
Wear rate is less than 1.5 × 10 ⁻² μm / 100,000 revolutions, and change in Rz is less than 0.10 μm. B: Minute wear of photoreceptor and minute fluctuation of surface shape.
Among those in which the change in wear rate or Rz exceeds the range of A, the wear rate is less than 3.0 × 10 ⁻² μm / 100,000 revolutions, and the change in Rz is less than 0.15 μm. C: Photoconductor wear Small and small fluctuation of surface shape.
Among those where the wear rate or the change in Rz exceeds the range of B, the wear rate is less than 1.0 × 10 ⁻¹ μm / 100,000 revolutions and the change in Rz is less than 0.20 μm. D: In the photoconductor Medium and moderate fluctuation of surface shape.
Among those where the change in wear rate or Rz exceeds the range of C, the wear rate is less than 3.0 × 10 ⁻¹ μm / 100,000 revolutions, and the change in Rz is less than 0.25 μm E: Photoconductor wear Large or very small variation in surface shape.
Wear rate or Rz change exceeds D range.
That is, the wear rate is 3.0 × 10 ⁻¹ μm / 100,000 rotations or more, or the change in Rz is 0.25 μm or more.

-Charging roller contamination Charge rollers before and after the durability test are put into an image forming apparatus that has not been subjected to the durability test, and character (Iroha) images, 5 dots 30 spaces (5D30S), 3D20S halftones, and latent image exposure are performed. The halftone image (bias HT) output without adjusting the development bias was evaluated.
A: No dirt or very little
Uneven image due to contamination of charging roller with bias HT is not visible B: Excellent. Dirt is virtually no problem
In the bias HT, image unevenness can be seen, but otherwise it cannot be seen.
C; Excellent. Dirt is virtually no problem
The image appears uneven with the bias HT and 3D20S.
D: Good. No problem in practical use
Image unevenness can be seen with the bias HT, 3D20S, and 5D30S.
E: There is a case where the image has an influence on the conventional level or practically.
Image unevenness can be seen in a character image or a lattice image.

  The evaluation results are shown in Table 8 below.

  From Table 8, it can be seen that very good results were obtained.

  In addition, when the amounts of inorganic bases α and β to be externally added were varied as shown in Table 9 below and evaluated in the same manner as in Examples 1 and 2, similar results were obtained.

[Examples 3 to 11]
Inorganic bases E12 to E17 were respectively pressure-molded to obtain solidified inorganic bases. An evaluation device for φ84 was used as an evaluation device, and the supply brush 108 described above was provided. The solidified inorganic base of the supply brush 108 and the amount of entry into the photoconductor 101 and the driving conditions were adjusted, and the solidified inorganic base was 5.0 × 10 ⁻⁹ g / mm ² per unit area of the photoconductor. The base was scraped off and supplied to the photoreceptor surface. The other conditions were evaluated under the conditions shown in Table 7. Good results were obtained with image flow. The results are shown in Table 8.
From Table 8, good results were obtained in image flow.
In addition, as a result of changing the use conditions of the supply brush and changing the supply amount of the inorganic base, 1.0 × 10 ⁻¹⁰ g / mm ² or more and 5 × 10 ⁻⁶ g / mm ² or less Similar results were obtained with the feed.
This is because when the supply is less than 1.0 × 10 ⁻¹⁰ g / mm ² , the brush supply becomes non-uniform and unevenness in the longitudinal direction of the photoconductor occurs in the flow characteristics. It seems to be done. On the other hand, when the supply exceeds 5 × 10 ⁻⁶ g / mm ² , the supply brush may be worn.

[Example 12]
In Examples 3 to 11, E08, which is calcium carbonate, was used as the inorganic base α. As a result, image flow characteristics were improved, cleaning characteristics such as cleaning blade wear and filming, and charging roller dirt characteristics were improved. This is probably due to the high lubricity of calcium carbonate.

[Examples 13 to 18]
In Example 12, the carrier metal-derived area ratio is 1.4 to 8 using the area ratio of the portion derived from the metal oxide of the carrier and the carriers C23 to C28 (see Table 6-1) having different area values. The evaluation was performed in the same manner as in Example 12 by shaking the surface ratio to 0.05% and 0.95 to 1.40 μm ² (see Table 4). As in Example 12, good results were obtained. The results are shown in Table 8.

[Example 19]
In Example 12, the part derived from the metal oxide of 6.672 μm ² or more of the carrier was changed to a carrier having 10.0 area%, and the same evaluation as in Example 12 was performed. The results are shown in Table 8. From Table 8, the image flow characteristics were further improved, cleaning characteristics such as cleaning blade wear and filming, and charging roller dirt characteristics were improved. This is thought to be due to the fact that the friction unevenness was reduced by suppressing the ratio of the large exposed portion of the core of the magnetic carrier.

[Examples 20 to 23]
In Example 12, the area ratio of the portion derived from the metal oxide of 6.672 μm ² or more of the carrier was changed by changing the total coating amount and the number of steps of the coating performed in multiple stages, and the same as in Example 19 Evaluation was performed. As in Example 19, good results were obtained. The results are shown in Table 8.

[Examples 24-26]
Furthermore, the part derived from the metal oxide of 2.780 μm ² or less of the magnetic carrier was changed to a carrier having 60.0 area% and 62.2 area%, and the same evaluation as in Examples 20 to 23 was performed. . The results are shown in Table 8. From Table 8, it can be seen that the image flow characteristics are further improved. This is thought to be due to the fact that the friction unevenness was reduced by suppressing the ratio of the large exposed portion of the core of the magnetic carrier. The slight difference in the wear of the photosensitive member is considered to be due to the difference in the elastic deformation rate Wu of the photosensitive member.

[Examples 27 to 30]
In Examples 27 to 30, the same evaluation was performed using photoreceptors having different elastic deformation rates Wu as shown in Table 6-1. The results are shown in Table 8. When Wu was 40% or more and 60% or less, the wear characteristics of the photoreceptor improved while maintaining good image flow. This is because the surface of the photoconductor has elasticity, so that the photoconductor is slightly elastically deformed at the contact portion with the magnetic carrier, and the area of the rubbing site by the magnetic carrier in the state where the inorganic base is present is reduced. This is thought to be due to an increase in rubbing efficiency.

[Examples 31 to 34]
In Examples 29 and 30, the same evaluation was performed using inorganic base α having a different degree of hydrophobicity. The results are shown in Table 8. When an inorganic base having a hydrophobization degree (methanol concentration at which the transmission density starts to decrease) of 40% or more and 60% or less was used, the image flow characteristics were further improved. This is considered to be due to the fact that the above-mentioned action efficiency with respect to acid and moisture is improved by having appropriate hydrophilicity.

[Examples 35 to 47]
In Examples 33 and 34, Vdr and Vsl were changed. Further, h was changed by adjusting the diameter and number of the developer-carrying members. Further, the magnetic flux density and magnetic pole pattern of the magnetic material included in the developer carrier, the distance between the developer carrier and the photoreceptor (development gap), the developer thickness on the surface of the developer carrier, and the like are adjusted. , A was changed. Each symbol indicates the following conditions.
Vsl: peripheral speed of developer carrying member (mm / second)
Vdr: Peripheral speed of photosensitive member (image carrier) (mm / second)
h: Development nip (length with which the magnetic brush contacts the photoreceptor) (mm)
m: sectional area of the magnetic brush (mm ² )
a: Magnetic brush density (lines / mm ² )
The same evaluation as in Examples 33 and 34 was performed by changing each of the above conditions as shown in Table 7-2. The results are shown in Table 8. In the present example in which the value of the following expression consisting of the above conditions is 0.7 or more and 3 or less, that is, the above expression 2 is satisfied, the image flow characteristics and the photoreceptor wear characteristics are further improved.
3 ≧ | Vsl−Vdr | · m · a · h / Vdr ≧ 0.7 (Expression 2)
The above improvement is thought to be due to the fact that the photosensitive multi-surface was efficiently rubbed in the state where the inorganic base was present by controlling the effective area where the magnetic brush and the surface of the photoconductor abut.

[Examples 48 to 50]
In Examples 46 and 47, the same evaluation was performed using a magnetic carrier having a magnetization intensity of 30 Am ² / kg or more and 65 Am ² / kg or less. The results are shown in Table 8.
From Table 8, it can be seen that the charging roller dirt characteristic and the image quality characteristic are further improved while maintaining the image flow characteristic and the like. By using a low-magnetization magnetic carrier, a fine and fine magnetic brush group can be formed, and the rubbing efficiency can be maintained.
The inorganic base is efficiently rubbed and scraped by a fine magnetic brush, and deteriorated or excess inorganic base is efficiently scraped and replaced in the development nip or the next cleaning step. As a result, it is considered that the charging roller dirt characteristic is improved.

[Examples 51 to 54]
In Example 50, E03 and E06, E07, E09, and E10 (in no particular order) having a high degree of hydrophobicity were mixed as inorganic bases to form solid inorganic bases.
These solidified inorganic bases were used and evaluated in the same manner as in Example 39. The results are shown in Table 8. From Table 8, it can be seen that very good results were obtained. Among them, better results were obtained in Examples 52 to 54 in which the degree of hydrophobicity of the inorganic base β (inorganic base having a higher degree of hydrophobicity) was 75% or more. This is probably because the use of an inorganic base having a high degree of hydrophobicity effectively rubbed or stirred the developing nip.

[Examples 55 to 56]
Evaluation was performed in the same manner as in Example 3 except that E20 and E21 were used as inorganic bases. In Examples 55 to 56, where the pH of the inorganic base was less than 7.5 or more than 10, the image flow characteristics were lower than in Example 3. The other items were the same as in Example 3.

[Comparative Examples 01 to 11]
In the above examples, the same evaluation as in the examples was performed using C14, C15, C16, C17, C18, C19, C20, C21, or E12, E18, E19 as the magnetic carrier without using an inorganic base. Went. Other detailed conditions are shown in Table 6-2 and Table 7-2, and the evaluation results are shown in Table 10, respectively.

  In this comparative example in which the magnetic carrier or the inorganic base corresponds to the following conditions, the image flow characteristic is E rank at 3%, which is the same level as the conventional level. Other characteristics were similar to the conventional level below D rank.

The area ratio occupying the portion derived from the metal oxide of the magnetic carrier is less than 0.5 area% or more than 10.0 area%, or the average area value is less than 0.45 μm ² or 1 More than 40 μm ² .

  In the contact portion between the magnetic brush and the photoconductor, no inorganic base is present or the average particle diameter of the intervening inorganic base is less than 30 nm or more than 300 nm.

  According to the configuration of the present invention, it is possible to improve the image flow characteristics and reduce the wear of the cleaning blade, the poor cleaning, and the image defects derived therefrom. In addition, since wear of the developer and the photosensitive member can be suppressed and contamination of the charging member can be suppressed, a good image can be obtained in the long term.

Claims (7)

A charging step for charging the image carrier;
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the image carrier;
The electrostatic latent image is developed to form a toner image by bringing a magnetic brush formed of a two-component developer carried on the surface of a developer carrying body to which a bias is applied into contact with the image carrying body. A development process to
A transfer step of transferring the toner image to a recording medium;
A cleaning step of removing transfer residual toner from the surface of the image carrier after transfer;
An image forming method having at least
The two-component developer contains a magnetic carrier and a toner,
The magnetic carrier is
A magnetic carrier having magnetic ferrite core particles and a resin,
In a reflected electron image of the magnetic carrier photographed at an acceleration voltage of 2.0 kV using a scanning electron microscope,
The area of the part derived from the metal oxide is 0.5 area% or more and 10.0 area% or less with respect to the particle projected area of the magnetic carrier,
Average area value of the portion derived from the metal oxide, and at 0.45 [mu] m ² or more 1.40 .mu.m ² or less,
An image forming method, wherein a basic inorganic compound having a number average particle diameter of 30 nm to 300 nm is interposed in a contact portion between the magnetic brush and the image carrier.   The image forming apparatus according to claim 1, wherein the basic inorganic compound is calcium carbonate.   The image forming method according to claim 1, wherein the image carrier has an elastic deformation rate Wu of a surface layer of 40% or more and 60% or less.   The image formation according to any one of claims 1 to 3, wherein the calcium carbonate has a methanol concentration of 40% or more and 60% or less at which light transmittance measured by measuring the degree of hydrophobicity of methanol starts. Method. The image forming method according to claim 1, wherein the image carrier, the developer carrier, and the magnetic brush satisfy the following formula.
3 ≧ | Vsl−Vdr | · m · a · h / Vdr ≧ 0.7
[Vsl represents the peripheral speed (mm / sec) of the developer carrier,
Vdr represents the peripheral speed (mm / sec) of the image carrier,
h represents a development nip (a length with which the magnetic brush contacts the image carrier) (mm);
m represents a magnetic brush cross-sectional area (mm ² ),
a indicates: magnetic brush density (lines / mm ² ). ] 6. The magnetic carrier according to claim 1, wherein the magnetic carrier has a magnetization intensity at 1000 / 4π (kA / m) of 30 (Am ² / kg) to 65 (Am ² / kg). The image forming method described in 1. The calcium carbonate, the image forming method according to any one of claims 2 to 6, characterized in that it is externally added to the toner.

Images