JP6732473B2 - Image forming method - Google Patents

Description

The present invention relates to an image forming method used in an electrophotographic system, an electrostatic recording system, an electrostatic printing system and a toner jet system.

A charging step of charging the image bearing member by using a charging member, an electrostatic latent image forming step of forming an electrostatic latent image on the image bearing member, and the electrostatic latent image is developed with toner to form a toner image. An electrophotographic method is known in which an image is obtained through a developing step, a transferring step in which the toner image is transferred to a recording medium, and the like. Image forming apparatuses using such electrophotography include copying machines and printers.

The performance required for these printers and copiers is increasing year by year, and it is necessary to satisfy the performances that are conventionally contradictory, such as compatibility with high speed and high image quality.
In particular, in order to support high image quality, it is required to support photographic images and graphic images. Of these images, there are many images in a so-called halftone region where the amount of applied toner is small, and it is strongly required to suppress roughness and uniformity.

On the other hand, miniaturization is also required for the electrophotographic apparatus, and in the charging step, the surface of the image carrier is charged by applying a voltage to a charging member that is in contact with or close to the surface of the image carrier. The contact charging method is widely used. As the voltage, a voltage of only a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage is used.
As a charging member, various studies have been conducted to achieve both high speed and high image quality. For example, Patent Document 1 discloses a charging member for contact charging, which has a surface layer having convex portions derived from resin particles or the like on the surface. By using such a charging member, the charging of the image carrier becomes more stable.

However, in the charging member described in Patent Document 1, when contacting the image bearing member, the contact pressure is applied to the convex portion derived from the resin particles on the surface of the roller-shaped charging member (hereinafter, also referred to as “charging roller”). Is easy to concentrate on. As a result, in long-term use, the surface of the image bearing member may be unevenly worn, resulting in vertical stripe-shaped image defects.
To address this problem, the charging member disclosed in Patent Document 2 contains bowl-shaped resin particles 11 having an opening in a conductive resin layer, as shown in (1a) and (1b) of FIG. To do. Then, the charging member has a concavo-convex shape derived from the opening and the edge of the bowl-shaped resin particles on the surface thereof.

By using the charging member described in Patent Document 2, the edge portion (hereinafter, simply referred to as the edge portion) of the opening of the bowl-shaped resin particles on the surface of the charging member is elastically deformed, so that the image bearing member is formed. The contact pressure is relieved. For the above reasons, it is possible to suppress uneven wear of the image carrier even at high process speeds even during long-term use.
As a result, the uniformity of halftone was improved, but further improvement is required in an environment where the process speed is faster and the product is used for a longer period of time. is necessary.

For example, Patent Document 3 proposes a toner used in a magnetic one-component developing method in which the magnetic characteristics and dielectric characteristics of the toner are defined, and the inorganic fine powder added to the toner and the dielectric characteristics of the toner are specified. There is. According to this, it is described that it is possible to provide a high-quality image with excellent dot reproducibility and less fog. However, there is room for further improvement in solving the above problems in the contact charging method.

JP, 2008-276026, A JP, 2011-248353, A JP, 2005-134751, A

An object of the present invention is to provide an image forming method capable of obtaining a uniform halftone image while suppressing non-uniform wear of an image carrier even under a high-speed process speed and a long-term use environment. That is.

The present invention relates to a charging step of charging an image bearing member using a charging member that contacts the image bearing member,
An electrostatic latent image forming step of forming an electrostatic latent image on the image carrier,
A developing step of developing the electrostatic latent image with toner to form a toner image;
A transfer step of transferring the toner image to a recording medium with or without an intermediate transfer member, and a step of heating and fixing the toner image transferred to the recording medium,
An image forming method having:
The charging member has a conductive base and a conductive resin layer as a surface layer on the base,
Conductive resin layer comprises a binder, and the resin particles bowl shape having an opening, the opening is held in a state exposed on the surface of the charging member,
The surface of the charging member has a concave portion derived from the opening of the bowl-shaped resin particles exposed on the surface, and a convex portion derived from the edge portion of the opening of the bowl-shaped resin particle exposed on the surface. Have
The toner contains a binder resin and magnetic particles,
The magnetic particles are magnetic particles having a core of magnetite particles and having a coating layer as an outermost layer on the surface of the magnetite particles,
The coating layer contains an oxide containing iron, and at least one oxide selected from the group consisting of oxides containing silicon and oxides containing aluminum,
The magnetite particles are magnetite particles having a shape of an octahedron and having a convex portion on a plane portion forming the octahedron,
The saturation magnetization of the toner is 15.0 Am ² /kg or more and 35.0 Am ² /kg or less at a magnetic field of 795.8 kA/m, and the dielectric constant ε'of the toner is 25.0 pF at a frequency of 10 kHz and a temperature of 40° C. / m or less than 40.0PF / m, an image forming method, characterized in that.

According to the present invention, there is provided an image forming method capable of obtaining a uniform halftone image while suppressing non-uniform wear of an image carrier even under a high-speed process speed and a usage environment for a long period of time. It becomes possible.

FIG. 6 is an explanatory diagram showing a configuration near a surface of a charging member of Patent Document 2. FIG. 3 is an explanatory diagram showing a configuration near a surface of an electrophotographic member (charging member) according to the present invention and a contact state with an image carrier. It is a schematic sectional drawing which shows an example of the charging member which concerns on this invention. It is a schematic diagram of a current measuring device of a charging member. FIG. 4 is a partial cross-sectional view of the vicinity of the surface of the charging member according to the present invention. FIG. 4 is a partial cross-sectional view of the vicinity of the surface of the charging member according to the present invention. It is explanatory drawing of the shape of the bowl-shaped resin particle used for this invention. It is a schematic sectional drawing which shows an example of the charging member which concerns on this invention. It is a schematic sectional drawing which shows an example of the charging member which concerns on this invention. It is an explanatory view of a state of oxygen permeation at the time of heating processing the charging member concerning the present invention. It is a schematic diagram showing one embodiment of a scanning electron microscope for calculating the brightness resulting from electric conductivity. It is a schematic sectional view showing an example of the electrophotographic apparatus according to the present invention. It is a schematic sectional drawing showing an example of the process cartridge which concerns on this invention. 3 is a TEM photograph of magnetic particles for toner (G-1) according to the present invention. (Make monochrome) It is a figure which shows the measuring method of the height of the convex part of the magnetic particle which concerns on this invention.

In the image forming method using the contact charging method, the present inventors obtain a uniform halftone image while suppressing uneven wear of the image carrier even under a high-speed process speed and a long-term use environment. The possible image forming method was examined.
The contact charging method charges the surface of the image bearing member by applying a voltage (a voltage of only DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage) to a charging member that is in contact with or close to the surface of the image bearing member. It is a method to do.

Therefore, when used at a high process speed for a long period of time, the surface of the image bearing member is likely to be worn, which may cause vertical streak-shaped image defects.
Further, since it rotates at a high speed, when the charging member is driven to rotate, the driven rotatability between the charging member and the image carrier tends to decrease, and due to the abnormal discharge caused by this, the horizontal streak-shaped image is mainly generated. May have occurred.

In order to improve the followability of the charging member, it is effective to make the surface of the charging member uneven so as to enhance the frictional property. As an example of forming the unevenness on the surface of the charging member, the unevenness can be formed by using a surface layer having a convex portion derived from resin particles or the like on the surface, such as the above-mentioned Patent Document 1. However, when contacting with the image carrier, the contact pressure is concentrated on the protrusions derived from the resin particles on the surface of the charging roller, which causes uneven wear on the surface of the image carrier during long-term use. In some cases, vertical streak-shaped image defects resulting from this may occur.

On the other hand, it is possible to solve the above-mentioned problem by using a charging member having on its surface unevenness derived from bowl-shaped resin particles. That is, the charging member used in the present invention has a conductive base and a conductive resin layer as a surface layer on the base. The conductive resin layer contains a bowl-shaped resin particle containing a binder and having an opening in a state where the opening is exposed on the surface of the charging member. Furthermore, the surface of the charging member has a concave portion derived from the opening of the bowl-shaped resin particles exposed on the surface and a convex portion derived from the edge portion of the opening of the bowl-shaped resin particle exposed on the surface. And a part.

Since the unevenness is formed on the surface of the charging member by using the charging member having the above structure, the driven rotatability is improved even at a high process speed. Furthermore, the edge pressure of the opening of the bowl-shaped resin particles on the surface of the charging member is elastically deformed, so that the contact pressure on the image carrier is relieved. For the above reasons, it is possible to suppress uneven wear of the image carrier even at high process speeds even during long-term use.

As a result, the uniformity of halftone has been greatly improved, but further improvement is required in an environment in which the process speed is higher and for a longer period of time. An intensive study was conducted on an image forming method capable of obtaining a more uniform halftone image.
As a result, it has been found that by using the following toner as a toner, a uniform halftone image can be obtained even in a high-speed process speed and a long-term use environment.
That is, the toner used in the image forming method of the present invention is characterized by the following (1) and (2).

(1) the saturation magnetization of the toner in a magnetic field 795.8 kA / m is less 15.0Am ² / kg or more 35.0Am ² / kg, more preferably, 20.0Am ² / kg or more 30.0Am ² / It is less than or equal to kg.
(2) The dielectric constant ε′ of the toner at a frequency of 10 kHz and a temperature of 40° C. is 25.0 pF/m or more and 40.0 pF/m or less, and more preferably 27.0 pF/m or more and 35.0 pF/m or less. ..

The developing method by electrophotography is roughly classified into a two-component developing method using carrier particles and a one-component developing method not using carrier particles. Compared to the two-component developing method, the one-component developing method does not have a carrier, and thus the maintainability of agent exchange can be omitted. Further, it is possible to omit means for detecting and correcting the ratio of the toner and the carrier, and it is preferably used in applications requiring high reliability and maintenance-free.

In copying machines and printers, downsizing of devices and energy saving are progressing, and the magnetic one-component developing method using a magnetic toner advantageous in these points is preferably used.
In the magnetic one-component developing method, a magnetic toner layer regulating member forms a magnetic toner layer on a toner carrier (hereinafter also referred to as a developing sleeve) provided with a magnetic field generating means such as a magnet roll. Then, this magnetic toner layer is conveyed to a developing area by a developing sleeve and developed.

In the magnetic one-component developing method, since the toner coat layer is formed on the developing sleeve by using magnetic force, the magnetic toner is arranged in a bead shape along the magnetic lines of the magnetic field generating means inside the developing sleeve, that is, a so-called toner chain. Forming a standing.
This magnetic toner layer is carried by a developing sleeve to a developing area and is developed. Therefore, in the magnetic one-component developing method, the toner tends to be developed in a state where the spikes are maintained.

The present inventors use a toner having a specific saturation magnetization and a dielectric constant, and by using a charging member having unevenness derived from bowl-shaped resin particles on the surface as a charging member, a higher process speed and It has been found that a more uniform halftone image can be obtained even in a usage environment for a longer period.
By using the charging member having the unevenness derived from the bowl-shaped resin particles on the surface, the image carrier is suppressed from uneven wear, and the followability between the image carrier and the charging member is improved, It becomes possible to form a more precise latent image and improve the uniformity of halftone.
In the magnetic one-component developing system, a uniform halftone image can be obtained up to a certain process speed without depending on the state of the spikes.
However, in the case of a higher process speed configuration, the opportunity for development is reduced, so it is necessary to properly control the state of the spikes and efficiently develop a dense latent image.

There are various factors that determine the shape of the spikes, but the saturation magnetization of the toner is an index that represents the magnetic properties of the toner, and is a factor that determines the shape and size of the spikes on the developing sleeve.
On the other hand, the dielectric constant is an index showing the charging characteristics of the toner.
Generally, in the magnetic one-component developing system, the developing sleeve and the image carrier are often not in contact with each other.
Therefore, it is considered that the magnetic effect is weakened with respect to the rising of the toner separated from the developing sleeve, and conversely, the electrostatic effect becomes dominant.
Furthermore, since a developing bias is applied during development, it is considered that the dielectric properties of the toner dominate the spiked state.

As a result of intensive studies by the present inventors, when the dielectric constant and the saturation magnetization of the toner are controlled within the ranges of the present application, the spikes are easily and efficiently ejected from the developing sleeve at the time of development and the development during flight is facilitated. Due to the bias, the spikes are likely to be scattered, and the precise latent image formed by the charging member of the present application can be faithfully reproduced.
It has been found that these effects remarkably appear particularly under the condition of a high process speed such that the process speed exceeds 380 mm/sec, and the effect continues even through the durability.

Further, the inventors of the present invention control both the dielectric constant and the saturation magnetization within a specific range, the electric polarization is controlled by the magnetic field generated by the toner due to the interaction such as the electromagnetic effect, and the dielectric constant falls within the range of the present application. We also found that it tends to be easier to control.
As a result of the above, it is considered possible to obtain a more uniform halftone image even in a usage environment for a long time and at a higher process speed than in the past.
The saturation magnetization amount of the toner of the present invention is controlled by the magnetization amount of the magnetic iron oxide contained in the toner and the content thereof.

The dielectric constant of the toner can be adjusted by selecting the binder resin, the type of magnetic particles, the content of magnetic particles, and the like.
FIG. 3 shows a circumferential cross section of a charging roller as an embodiment of the charging member according to the present invention.
As shown in FIG. 3 (3 a ), the charging roller has a conductive base 1 and a conductive resin layer 2. Alternatively, as shown in FIG. 3 (3 b ), the charging roller has a base 1, a conductive resin layer 21 as an intermediate layer on the base, and a conductive resin layer 22 as a surface layer on the intermediate layer. The conductive resin layer as the surface layer contains a binder.

FIG. 2 is a diagram showing the vicinity of the surface of the charging member. As shown in FIG. 2, a conductive resin layer (binder) 12, a bowl concave portion 17, and a bowl convex portion 18 are present on the surface of the electrophotographic member.
More specifically, as shown in FIG. 2 (2 a ), the conductive resin layer 12 as the surface layer forms the bowl-shaped resin particles 11 having openings in a state where the openings are exposed on the surface of the charging member. keeping. The surface of the charging member is
A binder,
A concave portion derived from the opening of the bowl-shaped resin particles 11 exposed on the surface (hereinafter, may be simply referred to as “bowl concave portion”);
And a convex portion (hereinafter sometimes simply referred to as “bowl convex portion”) derived from an opening edge of the bowl-shaped resin particle 11 (hereinafter sometimes simply referred to as “bowl edge”) ing.

Further, the charging member of the present invention has a conductive base and a conductive resin layer as a surface layer on the base, and the conductive resin layer contains a binder and has a bowl shape having an opening. Holding the resin particles in a state where the opening is exposed on the surface of the charging member,
The surface of the charging member has a concave portion derived from the opening of the bowl-shaped resin particles exposed on the surface and a convex portion derived from the edge of the opening of the bowl-shaped resin particle exposed on the surface. Have.
A part of the surface of the charging member is constituted by the conductive resin layer, and the conductive resin layer heats a layer of a conductive thermally crosslinkable rubber composition containing conductive fine particles in the presence of oxygen. It is preferably formed by crosslinking.

Further, it is preferable that a part of the surface of the charging member is constituted by the conductive resin layer, and the conductive fine particles are present in the recesses.

Further, a part of the surface of the charging member is composed of the conductive resin layer,
With a direct current voltage of 50 V or more and 100 V or less being applied between the electrode and the substrate arranged to face the charging member, the surface of the charging member was accelerated with a scanning electron microscope at an acceleration voltage of 1 kV and a magnification of 2000. Observe at double,
When the brightness at the convex portion is K1, the brightness at the bottom of the concave portion is K2, and the brightness at the exposed surface of the conductive resin layer is K3, K1, K2, and K3 are represented by the following mathematical formulas (1) to (3). ) Is preferably satisfied.
Formula (1) K2<K1
Formula (2) K3<K1
Formula (3) 0.8≦K2/K3≦1.2.

In the present invention, the luminances K1 to K3 are calculated by observing from the upper side of the surface of the charging member (Z direction in FIG. 2(2a)). The brightness K2 is the brightness due to the conductivity of the portion including the bowl-shaped resin particles and the binder positioned immediately below the resin particles. By measuring the brightness K2, it becomes possible to accurately evaluate the discharge state from the bottom of the recess of the bowl. The brightness K2 can be calculated by appropriately setting the acceleration voltage of the electron microscope.

The brightness of the present invention has a correlation with the conductivity of the observation site. That is, the smaller the brightness, the higher the conductivity, and the larger the brightness, the lower the conductivity. Equation (1) indicates that the conductivity EC1 of the convex portion of the bowl is lower than the conductivity EC2 of the bottom portion of the concave portion of the bowl. Formula (2) indicates that the conductivity EC1 of the convex portion of the bowl is lower than the conductivity EC3 of the binder exposed on the surface. When the charging member comes into contact with the image bearing member, the conductivity EC1 of the convex portion of the bowl that comes into contact with the surface of the image bearing member is low, so that the electrical conductivity between the surface of the image bearing member and the convex portion of the bowl is reduced. It is possible to maintain the attractive force.

Hereinafter, the electric attractive force acting between the surface of the image carrier and the convex portion of the bowl will be described. In the charging member having the uneven shape derived from the opening of the bowl-shaped resin particles exposed on the surface of the charging member, the convex portion 18 of the bowl is formed as shown in FIG. 2(2b) at the time of contact with the image carrier. It comes into contact with the image carrier 15 while being elastically deformed. On the other hand, at the time of forming an electrophotographic image, a voltage is applied to the charging member, so that the charging member charges the image carrier by discharging in a minute gap with the image carrier.

This discharge is what is called Townsend discharge, which is generated by ionizing the air in the minute gap. At that time, positive and negative charged particles generated by ionization of molecules in the air are guided to the surface of the image carrier or the charging member by the electric field formed between the minute gaps. Then, the charged particles are guided to the image carrier to charge the surface of the image carrier. In addition, charged particles having a polarity opposite to that of the charged particles induced on the image carrier are also induced and charged on the charging member. When the conductivity EC1 of the convex portion of the bowl is low, the electric charge induced by the Townsend discharge on the surface of the charging member is in a charged state. Due to this charged-up electric charge, an electric attractive force acts between the image carrier 15 and the convex portion of the bowl, and the attraction between the charging member and the image carrier is strengthened.

As described above, in the charging member of the present invention, the electric attractive force easily acts between the image carrier and the convex portion of the bowl. As a result, the driven rotatability is improved even in a severe environment where rotation and stop are repeated such as high process speed and intermittent mode, and the peripheral speed of rotation is different between the charging member and the image carrier. The phenomenon that appears irregularly (stick slip) is suppressed.

In addition to the above, the charging member of the present invention satisfies the above mathematical expression (3). K2/K3 in the mathematical expression (3) is the ratio of the luminance due to the conductivity EC2 at the bottom of the recess 17 of the bowl and the conductivity EC3 of the binder 12 exposed on the surface in FIG. 2(2a). The closer the value is to 1, the closer the electric conductivity EC2 at the bottom of the concave portion of the bowl and the electric conductivity EC3 at the binder exposed on the surface are, and thereby the concentration of the electric field on the binder 12 exposed on the surface is reduced. It is possible to alleviate and suppress the above-mentioned abnormal discharge. As a suitable means for keeping the value of K2/K3 within the range of Expression (3), bowl-shaped resin particles (material of bowl) are used as a material having a low oxygen permeability, and the surface of the charging member is exposed to the atmosphere. Means to oxidize and cure by the heat treatment of is mentioned.

The charging member of the present invention comprises, for example, a step of forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on the substrate,
By polishing the surface of the coating layer, a part of the shell of the hollow-shaped resin particles is removed to form a bowl shape having an opening, and a concave portion due to the opening of the bowl-shaped resin particle and an edge of the opening are formed. A step of forming a convex portion, and
It is manufactured through a step of allowing conductive fine particles to exist in the recesses.
The details will be described below.

<Charging member>
FIG. 3 is a schematic sectional view showing an example of the charging member according to the present invention.
The charging member of FIG. 3 (3 a) has a conductive base 1 and a conductive resin layer 2. The conductive resin layer may have a two-layer structure of conductive resin layers 21 and 22, as shown in FIG. 3 (3 b ). The conductive resin layer contains a binder and bowl-shaped resin particles.

The conductive substrate 1 and the conductive resin layer 2 or the layers sequentially stacked on the conductive substrate 1 (for example, the conductive resin layer 21 and the conductive resin layer 22 shown in FIG. 3B) are bonded to each other. You may adhere|attach via an agent. In this case, the adhesive is preferably electrically conductive. A known adhesive can be used as the conductive adhesive. Examples of the base material of the adhesive include thermosetting resins and thermoplastic resins, and known materials such as urethane-based, acrylic-based, polyester-based, polyether-based, and epoxy-based can be used. The conductive agent for imparting conductivity to the adhesive can be selected from the conductive fine particles described in detail later, and one kind can be used alone or two or more kinds can be used in combination.

[Conductive substrate]
The conductive substrate used for the charging member of the present invention has conductivity and has a function of supporting a conductive resin layer provided thereon. Examples of the material include metals such as iron, copper, aluminum and nickel and alloys thereof (stainless steel etc.).

[Conductive resin layer]
FIG. 5 is a partial cross-sectional view in the vicinity of the surface of the conductive resin layer forming the surface layer of the charging member according to the present invention. Some of the bowl-shaped resin particles 41 contained in the conductive resin layer are exposed on the surface of the charging member. The surface of the charging member has a concave portion 52 originating from the opening 51 of the bowl-shaped resin particles exposed on the surface and a convex portion originating from the edge 53 of the opening of the bowl-shaped resin particle exposed on the surface. And have. The edge 53 can have the shapes shown in (5a) and (5b). The shape of the edge 53 is not limited to these.

The height difference 54 between the apex of the convex portion derived from the edge 53 of the opening of the bowl-shaped resin particles and the bottom portion of the concave portion 52 defined by the shell of the bowl-shaped resin particles shown in FIG. 6 is 5 μm or more. It is preferably 100 μm or less, and particularly preferably 10 μm or more and 80 μm or less. Within the above range, it is possible to more reliably maintain the point contact of the edge of the bowl in the nip portion. Further, the ratio between the height difference 54 and the maximum diameter 55 of the bowl-shaped resin particles, that is, the [maximum diameter]/[height difference] of the resin particles is preferably 0.8 or more and 3.0 or less. .. Within the above range, it is possible to more reliably maintain the point contact of the edge of the bowl in the nip portion.

It is preferable that the surface condition of the conductive resin layer is controlled as described below by forming the uneven shape. The ten-point average surface roughness (Rzjis) is preferably 5 μm or more and 65 μm or less, and more preferably 10 μm or more and 50 μm or less. The average unevenness interval (Sm) on the surface is preferably 30 μm or more and 200 μm or less, and more preferably 40 μm or more and 150 μm or less. Within the above range, it is possible to more reliably maintain the point contact of the edge of the bowl at the nip portion. The method for measuring the ten-point average roughness (Rzjis) on the surface and the average unevenness interval (Sm) on the surface will be described in detail later.

7(a) to 7(e) show an example of bowl-shaped resin particles used in the image forming method of the present invention. In the present invention, the “bowl shape” means a shape having an opening 61 and a rounded concave portion 62 of the opening. The “opening” may have a flat edge on the bowl, as shown in (7a) and (7b) of FIG. 7, or may be a bowl of the bowl as shown in (7c) to (7e) of FIG. The edges may have irregularities.

The maximum diameter 55 of the bowl-shaped resin particles is preferably 10 μm or more and 150 μm or less, and more preferably 20 μm or more and 100 μm or less. In addition, the ratio of the maximum diameter 55 of the bowl-shaped resin particles to the minimum diameter 63 of the openings, that is, the [maximum diameter]/[the minimum diameter of the openings] of the bowl-shaped resin particles is 1.1 or more. It is more preferably 0 or less.

The thickness (difference between the outer diameter and the inner diameter of the edge) of the shell around the opening of the bowl-shaped resin particles is preferably 0.1 μm or more and 3 μm or less, and more preferably 0.2 μm or more and 2 μm or less. Further, the thickness of the shell is such that the “maximum thickness” is preferably 3 times or less the “minimum thickness”, and more preferably 2 times or less.

[binder]
As the binder contained in the conductive resin layer of the present invention, a known rubber or resin can be used. Examples of the rubber include natural rubber, vulcanized natural rubber, and synthetic rubber. The following are mentioned as a synthetic rubber. Ethylene propylene rubber, styrene butadiene rubber (SBR), silicone rubber, urethane rubber, isopropylene rubber (IR), butyl rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butadiene rubber (BR), acrylic rubber, epichlorohydrin rubber And fluororubber.

As the resin, for example, a resin such as a thermosetting resin or a thermoplastic resin can be used. Among them, fluororesin, polyamide resin, acrylic resin, polyurethane resin, acrylic urethane resin, silicone resin and butyral resin are more preferable. These may be used alone or in combination of two or more. Further, a monomer which is a raw material of these binders may be copolymerized to obtain a copolymer. For the reason described below, styrene-butadiene rubber (SBR), butyl rubber, acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butadiene rubber (BR) having a double bond in the molecule and having high heat resistance. Is more preferably used.

[Conductive particles]
The volume resistivity of the conductive resin layer is preferably 1×10 ² Ωcm or more and 1×10 ¹⁶ Ωcm or less in the environment of a temperature of 23° C. and a relative humidity of 50%, and is within the above range. This makes it easier to properly charge the image carrier by discharging. Therefore, known conductive fine particles may be contained in the conductive resin layer. Examples of the conductive fine particles include fine particles of metal oxide, metal, carbon black, and graphite. In addition, these conductive fine particles can be used alone or in combination of two or more. The content of the conductive fine particles in the conductive resin layer is 2 to 200 parts by mass, and particularly 5 to 100 parts by mass with respect to 100 parts by mass of the binder.

[Method of forming conductive resin layer]
The method for forming the conductive resin layer will be exemplified below. First, a coating layer of a composition in which hollow resin particles are dispersed in a binder is formed on a conductive substrate. After that, by polishing the surface of the coating layer, a part of the shell of the hollow-shaped resin particles is removed to form a bowl shape having an opening, and a concave portion due to the opening of the bowl-shaped resin particles and the bowl-shaped resin are formed. A convex portion is formed by the edge of the opening of the particle. Hereinafter, the shape including these irregularities is also referred to as “an irregular shape due to the opening of bowl-shaped resin particles”. Next, the conductivity of the material present on the surface of the coating layer is adjusted by applying conductive fine particles to the recesses, heat treatment of the coating layer in an oxygen-containing atmosphere, or the like.

Hereinafter, each step of the method for forming the conductive resin layer will be described in detail. The coating layer of the coating layer before the polishing step is referred to as a "preliminary coating layer". Further, the “hollow resin particle shell” in the raw material of the charging member is referred to as “bowl of bowl-shaped resin particles” in the charging member in which the bowl-shaped resin particles having openings are formed by the polishing treatment. ..

[Dispersion of resin particles in the preliminary coating layer]
First, a method of dispersing hollow resin particles in the preliminary coating layer will be described. As one method, hollow resin particles containing a gas inside, a coating film of a conductive resin composition dispersed in a binder is formed on a substrate, and the coating film is dried, cured, or The method of performing crosslinking etc. can be illustrated. In addition, the conductive resin composition may contain conductive particles. As a material used for the hollow-shaped resin particles, a resin having a polar group is preferable, and a resin having a unit represented by the following chemical formula (4) is more preferable, from the viewpoint of low gas permeability and high impact resilience. .. It is more preferable to have both the unit represented by the chemical formula (4) and the unit represented by the chemical formula (8) from the viewpoint of easily controlling the polishing property.

In the chemical formula (4), A is at least one selected from the group consisting of the following chemical formulas (5), (6) and (7). R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

In the chemical formula (8), R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

As another method, it is possible to exemplify a method of using heat-expandable microcapsules containing an encapsulating substance inside the particles and expanding the encapsulating substance by heating to form hollow resin particles. This is a method in which a thermally expandable microcapsule is dispersed in a binder to prepare a conductive resin composition, the conductive substrate is coated with the composition, and the composition is dried, cured, or crosslinked. In the case of this method, the encapsulating substance can be expanded by the heat at the time of drying, curing, or crosslinking of the binder used in the preliminary coating layer to form hollow resin particles. At that time, the particle size can be controlled by controlling the temperature condition.

When using heat-expandable microcapsules, it is necessary to use a thermoplastic resin as a binder. The following are mentioned as a thermoplastic resin. Acrylonitrile resin, vinyl chloride resin, vinylidene chloride resin, methacrylic acid resin, styrene resin, butadiene resin, urethane resin, amide resin, methacrylonitrile resin, acrylic acid resin, acrylic ester resin, methacrylic ester resin. Among them, in particular, it is preferable to use a thermoplastic resin composed of at least one selected from acrylonitrile resin, vinylidene chloride resin, and methacrylonitrile resin, which has a low gas permeability and high impact resilience, in order to control the conductivity distribution described later. Is more preferable. These thermoplastic resins may be used alone or in combination of two or more. Further, these thermoplastic resin monomers may be copolymerized to obtain a copolymer.

The substance to be encapsulated in the heat-expandable microcapsules is preferably one that expands into a gas at a temperature below the softening point of the thermoplastic resin, and examples thereof include the following. Low boiling point liquids such as propane, propylene, butene, normal butane, isobutane, normal pentane and isopentane, and high boiling point liquids such as normal hexane, isohexane, normal heptane, normal octane, isooctane, normal decane and isodecane.

The above heat-expandable microcapsules can be produced by a known production method such as a suspension polymerization method, an interfacial polymerization method, an interfacial precipitation method, or a submerged drying method. For example, in the suspension polymerization method, a polymerizable monomer, a substance to be encapsulated in the heat-expandable microcapsules, and a polymerization initiator are mixed, and the mixture is mixed in an aqueous medium containing a surfactant or a dispersion stabilizer. The method of carrying out suspension polymerization after dispersion in the above can be exemplified. A compound having a reactive group that reacts with the functional group of the polymerizable monomer and an organic filler may be added.

The following can be illustrated as a polymerization monomer. Acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, vinylidene chloride, vinyl acetate. Acrylic acid ester (methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, isobornyl acrylate, cyclohexyl acrylate, benzyl acrylate), methacrylic acid ester (methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, Isobutyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate). Styrene monomers, acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide, butadiene, ε-caprolactam, polyether, isocyanate. These polymerizable monomers can be used alone or in combination of two or more kinds.

The polymerization initiator is not particularly limited, but an initiator soluble in the polymerizable monomer is preferable, and known peroxide initiators and azo initiators can be used. Of these, azo initiators are preferred. Examples of azo initiators are given below. 2,2'-azobisisobutyronitrile, 1,1'-azobiscyclohexane 1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile. Of these, 2,2'-azobisisobutyronitrile is preferable. When using a polymerization initiator, 0.01-5 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.

As the surface active agent, an anionic surface active agent, a cationic surface active agent, a nonionic surface active agent, an amphoteric surface active agent, or a polymer type dispersant can be used. The amount of the surfactant used is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer. Examples of the dispersion stabilizer include the following. Organic fine particles (polystyrene fine particles, polymethyl methacrylate fine particles, polyacrylic acid fine particles and polyepoxide fine particles), silica (colloidal silica), calcium carbonate, calcium phosphate, aluminum hydroxide, barium carbonate, magnesium hydroxide and the like. The amount of the dispersion stabilizer used is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

The suspension polymerization is preferably carried out in a pressure-tight container and in a closed state. Further, the polymerizable raw material may be suspended in a disperser or the like and then transferred into a pressure resistant container for suspension polymerization, or may be suspended in the pressure resistant container. The polymerization temperature is preferably 50°C to 120°C. The polymerization may be carried out at atmospheric pressure, but it may be carried out under pressure (under a pressure obtained by adding 0.1 to 1 MPa to the atmospheric pressure) in order to prevent the substance contained in the thermal expansion microcapsules from being vaporized. preferable. After completion of the polymerization, solid-liquid separation and washing may be performed by centrifugation or filtration. In the case of solid-liquid separation or washing, drying or pulverization may be performed thereafter at a softening temperature or lower of the resin constituting the thermally expanded microcapsules. Drying and pulverization can be performed by a known method, and a flash dryer, a draft dryer and a Nauta mixer can be used. Further, the drying and the pulverization can be simultaneously performed by a pulverization dryer. The surfactant and the dispersion stabilizer can be removed by repeating washing filtration after the production.

[Method of forming preliminary coating layer]
Next, a method of forming the preliminary coating layer will be described. As a method for forming the preliminary coating layer, a layer of the conductive resin composition is formed on the conductive substrate by a coating method such as electrostatic spray coating, dipping coating, or roll coating, and the layer is dried, heated, crosslinked, or the like. The method of hardening a layer is mentioned. In addition, a method of adhering or coating a sheet-shaped or tube-shaped layer obtained by forming a film of a conductive resin composition to a predetermined thickness and curing the film or bonding it to a conductive substrate. Furthermore, a method of forming a preliminary coating layer by putting a conductive resin composition in a mold in which a conductive substrate is placed and curing the composition is exemplified. Further, in particular, when the binder is rubber, the conductive base and the unvulcanized rubber composition can be integrally extruded using an extruder equipped with a crosshead. The crosshead is an extrusion die that is used to form a coating layer for electric wires and wires and that is installed and used at the tip of the cylinder of an extruder. Then, after drying, curing, crosslinking, etc., the surface of the preliminary coating layer is polished to remove a part of the shell of the hollow resin particles to form a bowl shape. A cylindrical polishing method or a tape polishing method can be used as the polishing method. Examples of the cylindrical polishing machine include a traverse type NC cylindrical polishing machine and a plunge cut type NC cylindrical polishing machine.

(A) When the thickness of the preliminary coating layer is 5 times or less of the average particle diameter of the hollow resin particles: When the thickness of the preliminary coating layer is 5 times or less of the average particle diameter of the hollow resin particles, In many cases, convex portions derived from hollow resin particles are formed on the surface. In this case, a part of the convex portion of the hollow-shaped resin particles may be removed to form a bowl shape, and an uneven shape due to the opening of the bowl-shaped resin particles can be formed. In this case, it is more preferable to use a tape polishing method in which the pressure applied to the preliminary coating layer during polishing is relatively small. As an example, the preferred range of polishing conditions for the preliminary coating layer when using the tape polishing method is shown below.

The polishing tape is obtained by dispersing polishing abrasive grains in a resin and applying it to a sheet-shaped substrate. Examples of the abrasive grains include aluminum oxide, chromium oxide, silicon carbide, iron oxide, diamond, cerium oxide, corundum, silicon nitride, silicon carbide, molybdenum carbide, tungsten carbide, titanium carbide and silicon oxide. The average grain size of the polishing abrasive grains is preferably 0.01 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less. The average particle diameter of the above-mentioned abrasive grains is the median diameter D50 measured by the centrifugal sedimentation method. The preferable range of the count of the polishing tape having the above-mentioned preferable range of abrasive grains is 500 or more and 20,000 or less, and more preferably 1,000 or more and 10,000 or less. Specific examples of the polishing tape will be given below. MAXIMA LAP, MAXIMA T type (trade name, Reflight Co., Ltd.), Lapica (trade name, manufactured by Kovacs Co., Ltd.), microfinishing film, wrapping film (trade name, manufactured by 3M Japan Co., Ltd.), mirror film, wrapping Film (trade name, manufactured by Sankyo Rikagaku Co., Ltd.), Mibox (trade name, manufactured by Mibox Co., Ltd.).

The feed rate of the polishing tape is preferably 10 mm/min or more and 500 mm/min or less, more preferably 50 mm/min or more and 300 mm/min or less. The pressing pressure of the polishing tape on the preliminary coating layer is preferably 0.01 MPa or more and 0.4 MPa or less, more preferably 0.1 MPa or more and 0.3 MPa or less. A backup roller may be brought into contact with the preliminary coating layer via an abrasive tape in order to control the pressing pressure. Moreover, in order to obtain a desired shape, the polishing treatment may be performed plural times. The number of rotations is preferably set to 10 rpm or more and 1000 rpm or less, more preferably 50 rpm or more and 800 rpm or less. By setting the above conditions, it is possible to more easily form the uneven shape due to the opening of the bowl-shaped resin particles on the surface of the preliminary coating layer. Even if the thickness of the preliminary coating layer is within the above range, the uneven shape due to the opening of the bowl-shaped resin particles can be formed by the method (b) described below.

(B) When the thickness of the preliminary coating layer is more than 5 times the average particle diameter of the hollow resin particles When the thickness of the preliminary coating layer is more than 5 times the average particle diameter of the hollow resin particles, In some cases, no convex portion derived from hollow resin particles is formed on the surface. In such a case, it is possible to form the uneven shape due to the opening of the bowl-shaped resin particles by utilizing the difference in the polishing property between the hollow-shaped resin particles and the material of the preliminary coating layer. The hollow resin particles have a high impact resilience because they enclose gas inside. On the other hand, as the binder of the preliminary coating layer, rubber or resin having a relatively low impact resilience and a small elongation is selected. As a result, the preliminary coating layer can be easily polished, and the hollow resin particles can be hardly polished. When the preliminary coating layer in the above state is polished, the hollow-shaped resin particles are not polished in the same state as the preliminary coating layer, and may have a bowl shape in which a part of the shell of the hollow-shaped resin particles is removed. it can. This makes it possible to form an uneven shape due to the opening of the bowl-shaped resin particles on the surface of the preliminary coating layer. Since this method is a method of forming an uneven shape by utilizing the difference in the abrasiveness between the hollow-shaped resin particles and the material of the preliminary coating layer, the material (binder) used for the preliminary coating layer is rubber. Is preferred. Among these, acrylonitrile butadiene rubber, styrene butadiene rubber, and butadiene rubber are particularly preferably used from the viewpoints of low impact resilience and small elongation.

[Polishing method]
As a polishing method, a cylindrical polishing method or a tape polishing method can be used. However, since it is necessary to remarkably make a difference in the polishing property of the material, it is preferable to perform the polishing condition faster. From this viewpoint, it is more preferable to use the cylindrical polishing method. Among the cylindrical polishing methods, it is more preferable to use the plunge cut method from the viewpoint that the longitudinal direction of the preliminary coating layer can be simultaneously polished and the polishing time can be shortened. Further, from the viewpoint of making the polishing surface uniform, it is preferable that the spark-out process (polishing process with an intrusion speed of 0 mm/min) that has been conventionally performed be as short as possible or not performed. As an example, the rotational speed of the plunge-cut type cylindrical polishing grindstone is preferably 1000 to 4000 rpm, and particularly preferably 2000 to 4000 rpm. The penetration speed into the preliminary coating layer is preferably 5 to 30 mm/min, more preferably 10 to 30 mm/min. At the end of the invasion step, the polishing surface may have a break-in step, and it is preferable that the intrusion rate is 0.1 or more and 0.2 mm/min or less and the time is within 2 seconds. The spark-out process (polishing process at an intrusion speed of 0 mm/min) is preferably 3 seconds or less. The rotation speed is preferably set to 50 rpm or more and 500 rpm or less, and more preferably set to 200 rpm or more. By setting the above conditions, it is possible to more easily form the unevenness due to the opening of the bowl-shaped resin particles on the surface of the preliminary coating layer.
In the following description, the preliminary coating layer that has been subjected to the polishing treatment is simply referred to as "coating layer".

[Method of controlling conductivity]
The charging member of the present invention satisfies the above formulas (1) to (3). K1 to K3 in the formulas (1) to (3) indicate the luminance due to the conductivity of each part of the surface of the charging member, and in order to satisfy the formulas (1) to (3), “the coating layer It is preferable to control the electric conductivity of each part of ".

First, in order to satisfy the formulas (1) and (2), the material of the bowl portion of the bowl-shaped resin particles described above may be set to a resin having a low volume resistivity of 10 ¹⁰ Ωcm or more and low conductivity. preferable. Subsequently, in order to satisfy the mathematical formula (3), it is preferable to control the conductivity of the binder of the coating layer and the conductivity of the recesses derived from the bowl-shaped resin particles. The control of the conductivity can be performed in a step after the polishing step described above, and the control method will be described in detail below.

FIG. 8 shows the state after the polishing step. First, as described above, the bowl-shaped resin particles 81 are formed of a material having a low conductivity or an insulating material. By doing so, the conductivity of the recess 83 derived from the bowl-shaped resin particles in FIG. 8 can be made lower than that of the binder portion 85 beside the bowl-shaped resin particles.

Subsequently, the following two methods can be exemplified as the means for controlling the conductivity of the coating layer for satisfying the mathematical expression (3) after the polishing step.
[Method 1] A method in which conductive fine particles are present in the recesses derived from bowl-shaped resin particles.
[Method 2] The material of the bowl of resin particles having a bowl shape has an oxygen permeability of 140 cm ³ /(m ² ·
As a material having a low oxygen permeability of 24 h·atm) or less, the surface of the coating layer is heat-treated in an oxygen-containing atmosphere (such as an air atmosphere).

The above [Method 1] will be described with reference to FIG. 9. When the conductive fine particles 16 are applied to the recesses 17 derived from the bowl-shaped resin particles 11, the conductivity of the recesses 17 can be increased. Then, by selecting the type of the conductive fine particles 16 to be applied, it becomes possible to control the value of K2/K3 within the range that satisfies the mathematical expression (3). As the conductive fine particles to be applied, the above-mentioned conductive fine particles can be used, but it is preferable to use the conductive fine particles having a volume resistivity of 10 ⁰ to 10 ⁸ Ω·cm, and 10 ² to 10 ⁵ Ω. -Cm conductive fine particles are more preferable. The resin used for the binder is not particularly limited.

The above [Method 2] will be described with reference to FIGS. 8 and 10. In the heat treatment under the oxygen-containing atmosphere, the degree of crosslinking of the resin increases due to the progress of oxidative crosslinking. Along with that, the conductivity of the resin tends to decrease. This is because the molecular mobility decreases as the oxidative crosslinking progresses. The degree of oxidative crosslinking can be adjusted by the heat treatment temperature and the oxygen concentration in the crosslinked portion. Regarding the heating temperature, the higher the temperature, the higher the degree of cross-linking. Regarding the oxygen concentration, the higher the oxygen concentration in the cross-linking portion, the more oxidative cross-linking can proceed. Therefore, by controlling the heating temperature and the oxygen concentration in the resin, it is possible to control the conductivity of the binder portion 85 beside the bowl-shaped resin particles and the portion directly below the bowl-shaped resin particles in FIG. It will be possible. At this time, as a method of controlling the oxygen concentration in the resin, adjusting the oxygen permeability of the bowl of the bowl-shaped resin particles is useful.

In a general heat treatment, oxidative crosslinking proceeds from the surface of the coating layer to the inside of the coating layer (direction of arrow Z2 in FIG. 10).
When the bowl-shaped resin particles have a low oxygen permeability, the oxygen transmission is blocked by the bowl-shaped resin particles 81 as shown in FIG. As a result, oxidative crosslinking of the immediately lower portion 84 is suppressed. As a result, the conductivity of the immediately lower portion 84 becomes higher than the conductivity of the binder portion 85. Therefore, the conductivity value of the concave portion 83 and the conductivity value of the binder portion 85 in FIG. 8 tend to be close to each other, and the value of K2/K3 in Expression (3) is close to 1.

On the other hand, when the oxygen permeability of the bowl-shaped resin particles is high, the bowl-shaped resin particles 81 permeate oxygen as shown in FIG. Oxygen is supplied, and oxidative cross-linking proceeds in the immediately lower portion 84 as in the binder portion 85. Therefore, the conductivity value of the immediately lower portion 84 and the conductivity value of the binder portion 85 are substantially the same, and the conductivity value of the recess 83 and the conductivity value of the binder portion 85 in FIG. 8 are heated in the atmosphere. Even if the processing is performed, the values are not close to each other, and the value of K2/K3 in Expression (3) does not become close to 1.

As mentioned above, it can be said that forming the bowl of bowl-shaped resin particles with a material having a low oxygen permeability is very useful as a method for controlling the conductivity of the present invention.
Therefore, acrylonitrile resin, vinylidene chloride resin, methacrylonitrile resin, methyl methacrylate resin, and copolymers of these resins, which have low oxygen gas permeability, are used as the material for forming the bowl of bowl-shaped resin particles. It is preferable. In particular, it is more preferable to use an acrylonitrile resin or a vinylidene chloride resin. This makes it possible to more easily control the above-described conductivity.

On the other hand, changing the temperature of the heat treatment can also control the degree of oxidative crosslinking, which is a useful method for controlling the conductivity. However, the progress of oxidative crosslinking due to the heating is accelerated as the temperature increases, but at the same time, shrinkage occurs due to volatilization of the low molecular weight component of the binder. When the above phenomenon occurs, the conductive fine particles dispersed in the binder become dense and the conductivity of the surface of the charging member tends to be significantly increased. As a result, when the mathematical expression (3) is not satisfied, There is. Therefore, the heating temperature is preferably controlled to 180 to 210°C, and more preferably 190 to 200°C.

As the heat treatment method, known means such as a hot air continuous furnace, an oven, a near infrared heating method, a far infrared heating method can be used, but coating is performed in an oxygen-containing atmosphere (in the presence of oxygen). The method is not particularly limited to these methods as long as the surface of the layer can be heat-treated.

As the resin as the binder, it is preferable to use a resin that promotes the effect of oxidative crosslinking when heated in an oxygen-containing atmosphere. Specifically, styrene-butadiene rubber (SBR), butyl rubber, acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butadiene rubber (BR) having a double bond in the molecule and having high heat resistance are used. It is preferable to do. The conductive resin layer preferably contains a crosslinked rubber as a binder and is formed by thermally crosslinking a layer of a conductive thermally crosslinkable rubber composition containing conductive fine particles in the presence of oxygen.

Although the method of forming the conductive resin layer has been described above, examples of the method of manufacturing the charging member according to the present invention are as follows [1] to [5].

[1] a step of forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on a conductive substrate,
By polishing the surface of the coating layer, a part of the shell of the hollow resin particles is removed to form a bowl shape having an opening, and a concave portion due to the opening of the bowl-shaped resin particles and a convex portion due to the edge of the opening are formed. And a step of forming a part, and
A method of manufacturing a charging member, comprising the step of causing conductive fine particles to exist in the recesses.

[2] A method of manufacturing a charging member, comprising a step of repolishing the surface of the coating layer after the step of allowing the conductive fine particles to exist.

[3] a step of forming a coating layer of a heat-crosslinkable rubber composition containing conductive fine particles, heat-crosslinkable rubber, and hollow resin particles on the substrate,
By polishing the surface of the coating layer, a part of the shell of the hollow-shaped resin particles is removed to form bowl-shaped resin particles having openings, and the bowl is formed with the openings exposed on the surface. A step of forming a layer in which shaped resin particles are held, and
The thermally crosslinkable rubber in the coating layer is thermally crosslinked in the presence of oxygen to have a concave portion derived from the opening and a convex portion derived from the edge of the opening on the surface, and And a step of obtaining a charging member whose part is composed of a conductive resin layer.

[4] The method for producing a charging member according to any one of [1] to [3], wherein the hollow resin particles have a shell oxygen permeability of 140 cm ³ /(m ² ·24h·atm) or less.
[5] The method for producing a charging member according to any one of [1] to [4], wherein the shell of the hollow resin particles has a volume resistivity of 10 ¹⁰ Ωcm or more.

<Toner>
Hereinafter, the toner used in the image forming method of the present invention will be described in detail.
[Magnetic particles for toner]
The magnetic particles contained in the magnetic one-component toner include the following. Magnetic iron oxides such as magnetite, maghemite and ferrite, and magnetic iron oxides containing other metal oxides; metals such as Fe, Co and Ni, or these metals and Al, Co, Cu, Pb, Mg and Ni , Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, alloys with metals such as V, and mixtures thereof.

Among these, magnetic particles satisfying the following 1) to 5) are particularly preferable.
1) A magnetite particle is used as a core, and a coating layer as an outermost layer is provided on the surface of the magnetite particle.
2) The coating layer contains an oxide containing iron and at least one oxide selected from the group consisting of oxides containing silicon and oxides containing aluminum.
3) The magnetite particles have an octahedron shape, and have a convex portion on a plane portion forming the octahedron.

4) The coating layer covers the entire surface of the magnetite particles evenly, or the surface of the magnetite particles is partially exposed. In any of the coating modes, the coating layer thinly coats the surface of the magnetite particles. The thickness of the coating layer is preferably 1 nm or more and 50 nm or less, and more preferably 2 nm or more and 20 nm or less.
5) The coating layer contains an oxide containing iron and an oxide containing silicon or aluminum.

When the TEM (transmission electron microscope) observation of the magnetic particles is carried out by the method described in the example, the convex portion is projected when the flat portion of the octahedron is used as the base surface, as shown in FIG. It refers to the part that exists.
In the present invention, what has a protruding height of 1 nm or more when the flat surface of the octahedron is the base surface is regarded as a convex portion.
The height of the convex portion is preferably 1 nm or more and 40 nm or less, and more preferably 3 nm or more and 20 nm or less.
The convex portions may be present on the flat surface portion of the octahedron without a gap or may be sparsely present. The number of protrusions is not particularly limited, but it is sufficient that there is one or more protrusions for each magnetic particle.

In order for the magnetic particles of the present invention to have a convex portion on the plane portion of the octahedron, the molar ratio of silicon to iron in the coating layer is preferably 0.2 or more and 1.0 or less, and 0.3 or more and 0 or less. It is particularly preferable that it is 1.9 or less. The molar ratio of aluminum to iron is preferably 0.5 or more and 2.0 or less, and particularly preferably 0.5 or more and 1.8 or less.
The height of the protrusions can be adjusted by changing the above-mentioned molar ratio of silicon to iron, molar ratio of aluminum to iron, and the number average particle diameter of the core particles in the coating layer.

The proportions of these elements and the like can be measured by the following methods 1) to 3).
1) The coated magnetite particles of the present invention are suspended in 5% by mass diluted sulfuric acid at 50°C to obtain a measurement solution.
2) A part of the measurement liquid is sampled at regular intervals and filtered with a membrane filter.
3) The concentrations of silicon, aluminum and iron contained in the obtained filtrate are quantified by an ICP (Inductively Coupled Plasm) emission spectroscopic analyzer.
In this measurement, the amount of iron dissolved until silicon and aluminum are no longer detected is taken as the amount of iron in the coating layer.

By using the magnetic iron oxide particles having a convex portion on the flat surface of the octahedron, the dispersion of the magnetic particles in the toner is improved, the variation of the dielectric constant and the saturation magnetization of each toner is reduced, and the toner is used for a long time. Also in this case, it is possible to stably obtain a uniform halftone image.
The toner used in the image forming method of the present invention preferably contains 30 parts by mass or more and 70 parts by mass or less of magnetic particles with respect to 100 parts by mass of the binder resin. The above range is preferable because the dielectric constant and magnetic properties of the toner can be controlled in a more preferable range in a well-balanced manner.

[Binder resin for toner]
Examples of the binder resin used in the toner of the present invention include the following. Vinyl resin, styrene resin, styrene copolymer resin, polyester resin, polyol resin, polyvinyl chloride resin, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, Silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin. Among them, the resin preferably used is a styrene copolymer resin, a polyester resin, a hybrid resin in which a polyester resin and a vinyl resin are mixed, or both of them are partially reacted.

Among them, the polyester resin is preferable as the binder resin of the toner used in the image forming method of the present invention.
Further, in the present invention, the polyester-based resin means a resin in which 50% by mass or more of the constituent components of the resin is composed of a polyester resin or a polyester portion.
Further, a hybrid resin is more preferable as the binder resin for the toner. The hybrid resin is a resin that has both properties as a polyester resin and properties as a vinyl resin. Therefore, it is possible to uniformly disperse various materials used for the toner without depending on their polarities or surface properties. Therefore, the dielectric constant can be stably controlled, which is preferable.

The following compounds may be mentioned as the polyester-based monomer constituting the polyester-based unit of the binder resin according to the present invention or the above-mentioned hybrid resin.

Examples of the alcohol component include the following. Ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol , 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, a bisphenol derivative represented by the following formula (9), and diols represented by the following formula (10).

Examples of the acid component include the following. Benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride, or anhydrides thereof. Alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid, or anhydrides thereof. Succinic acid or an anhydride thereof substituted with an alkyl group or an alkenyl group having 6 to 18 carbon atoms. Unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid, or anhydrides thereof.

The polyester resin or polyester-based unit according to the present invention is preferably a polyester resin containing a cross-linked structure with a trivalent or higher polyvalent carboxylic acid or its anhydride and/or a trivalent or higher polyhydric alcohol.
Examples of trivalent or higher polycarboxylic acids or anhydrides thereof include the following. 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, pyromellitic acid and their acid anhydrides or lower alkyl esters.
Examples of the trihydric or higher polyhydric alcohol include the following. 1,2,3-propanetriol, trimethylolpropane, hexanetriol, pentaerythritol.
In the binder resin of the present invention, an aromatic carboxylic acid that is highly stable due to environmental changes is particularly preferable, and examples thereof include 1,2,4-benzenetricarboxylic acid and its anhydride.

Examples of the vinyl-based monomer that constitutes the vinyl-based polymer unit of the vinyl-based resin or the hybrid resin used for the binder resin according to the present invention include the following compounds.
Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethyl Styrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene Such as styrene and its derivatives; styrene unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; unsaturated polyenes such as butadiene and isoprene; halogenated vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, etc. Vinyls; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate. Α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, acrylic acid n- Acrylic esters such as butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether, Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and the like N-vinyl compounds; vinylnaphthalene compounds; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

Further, the following may be mentioned. Unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid, fumaric acid, mesaconic acid; unsaturated acids such as maleic anhydride, citraconic anhydride, itaconic anhydride, alkenylsuccinic anhydride Dibasic acid anhydrides: maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, alkenylsuccinic acid Unsaturated dibasic acid esters such as acid methyl half ester, fumaric acid methyl half ester and mesaconic acid methyl half ester; unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid; acrylic acid, methacrylic acid, croton Α,β-Unsaturated acids such as acids and cinnamic acids; α,β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, and anhydrides of the α,β-unsaturated acids and lower fatty acids Monomers having a carboxy group such as alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, acid anhydrides thereof and monoesters thereof.

Further, the following may be mentioned. Acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; 4-(1-hydroxy-1-methylbutyl)styrene, 4-(1-hydroxy-1-methyl) Hexyl) A monomer having a hydroxy group such as styrene.

In the toner of the present invention, the vinyl-based resin or vinyl-based polymer unit used as the binder resin may have a crosslinked structure crosslinked with a crosslinking agent having two or more vinyl groups. Examples of the cross-linking agent used in this case include the following. Aromatic divinyl compounds (divinylbenzene, divinylnaphthalene); Diacrylate compounds linked by an alkyl chain (ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5- Pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and the above compounds in which acrylate is replaced with methacrylate); diacrylate compounds linked by an alkyl chain containing an ether bond (for example, , Diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #400 diacrylate, polyethylene glycol #600 diacrylate, dipropylene glycol diacrylate, and any of the above compounds in which the acrylate is replaced with methacrylate. ); Diacrylate compounds having a chain containing an aromatic group and an ether bond [polyoxyethylene (2)-2,2-bis(4hydroxyphenyl)propane diacrylate, polyoxyethylene (4)-2, 2-bis(4hydroxyphenyl)propanediacrylate, and those in which the acrylates of the above compounds are replaced by methacrylates]; polyester type diacrylate compounds (“MANDA” manufactured by Nippon Kayaku Co., Ltd.).

The following are mentioned as a polyfunctional crosslinking agent. Pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and compounds in which the acrylates of the above compounds are replaced by methacrylates; triallyl cyanurate, triallyl trimellitate ..

These crosslinking agents are preferably used in an amount of 0.01 parts by mass or more and 10.00 parts by mass or less, and more preferably 0.03 parts by mass or more and 5.00 parts by mass or less, relative to 100 parts by mass of the other monomer components. preferable.
Among these cross-linking agents, those which are preferably used in the binder resin from the viewpoints of fixing property and anti-offset property, are linked by a chain containing an aromatic divinyl compound (particularly divinylbenzene), an aromatic group and an ether bond. Diacrylate compounds may be mentioned.

Examples of the polymerization initiator used for the polymerization of the vinyl resin or vinyl polymer unit include the following. 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2, 2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobisisobutyrate, 1,1'-azobis(1-cyclohexanecarbonitrile), 2-(carbamoylazo)-isobutyronitrile , 2,2'-azobis(2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2-azobis(2-methylpropane), methyl ethyl ketone peroxide, Acetoneacetone peroxide, ketone peroxides such as cyclohexanone peroxide, 2,2-bis(tert-butylperoxy)butane, tert-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethyl Butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, α,α′-bis(tert-butylperoxyisopropyl)benzene, isobutyl peroxide, octanoyl peroxide, Decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, Di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxycarbonate, dimethoxyisopropyl peroxydicarbonate, di(3-methyl-3-methoxybutyl)peroxycarbonate, acetylcyclohexylsulfonyl peroxide, tert- Butyl peroxyacetate, tert-butyl peroxyisobutyrate, tert-butyl peroxy neodecanoate, tert-butyl peroxy 2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate , Tert-butyl peroxyisopropyl carbonate, di-tert-butyl peroxyisophthalate, tert-butyl peroxyallyl carbonate, tert-amyl peroxy 2-ethylhexanoate, di-tert-butyl peroxy Oxyhexahydroterephthalate, di-tert-butylperoxyazelate.

In the present invention, when the above-mentioned hybrid resin is used as the binder resin, it is preferable that the vinyl resin and/or polyester resin component contains a monomer component capable of reacting with both resin components. Among the monomers constituting the polyester resin component, those capable of reacting with the vinyl resin include, for example, unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid, or anhydrides thereof. Among the monomers constituting the vinyl resin component, those capable of reacting with the polyester resin component include those having a carboxy group or a hydroxy group, and acrylic acid or methacrylic acid esters.

As a method for obtaining a reaction product of a vinyl resin and a polyester resin, in the presence of a polymer containing a monomer component capable of reacting with each of the above-mentioned vinyl resin and polyester resin, one or both resins are A method of causing a polymerization reaction is preferable.

Although the above binder resins may be used alone, two kinds of resins having different softening points, a high softening point resin (H) and a low softening point resin (L) are mixed in an arbitrary range. You may use it. The high softening point resin (H) preferably has a softening point of 120° C. or higher and 170° C. or lower. The low softening point resin (L) preferably has a softening point of 70° C. or higher and lower than 120° C.

Such a system is preferable because the molecular weight distribution of the toner can be designed relatively easily and a wide fixing area can be provided.
When one type of binder resin is used alone, the softening point Tm is preferably 95°C or higher and 170°C or lower, and more preferably 120°C or higher and 160°C or lower. When Tm is within the above range, the balance between the high temperature offset resistance and the low temperature fixability becomes good.
Further, the glass transition temperature (Tg) of the binder resin is preferably 45° C. or higher from the viewpoint of storage stability. Further, from the viewpoint of low temperature fixability, Tg is preferably 75° C. or lower, and particularly preferably 65° C. or lower.

[Release agent for toner]
In the present invention, a releasing agent (wax) may be used as necessary in order to impart a releasing property to the toner. As the wax, hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax are preferably used because of their ease of dispersion in toner particles and high releasability. If desired, one or more waxes may be used together in a small amount. Examples include:

Oxides of aliphatic hydrocarbon wax such as oxidized polyethylene wax or block copolymers thereof; waxes containing fatty acid ester as a main component such as carnauba wax, sazol wax and montanic acid ester wax; deoxidized carnauba Deoxidized part or all of fatty acid esters such as wax. Further, the following may be mentioned. Saturated straight chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as pracidic acid, eleostearic acid and parinaric acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubayl alcohol, ceryl alcohol, melyl alcohol Saturated alcohols such as sil alcohol; long-chain alkyl alcohols; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylenebisstearic acid amide, ethylenebiscapric acid amide Saturated bisamides such as ethylene bis lauric acid amide and hexamethylene bis stearic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N,N'-dioleyl adipamide, N,N-dioleyl Unsaturated fatty acid amides such as sebacic acid amide; aromatic bisamides such as m-xylene bisstearic acid amide and N,N-distearylisophthalic acid amide; calcium stearate, calcium laurate, zinc stearate, magnesium stearate, etc. Fatty acid metal salts (commonly called metal soap); waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid; fatty acids such as behenic acid monoglyceride Partial esterified product of polyhydric alcohol; methyl ester compound having hydroxyl group obtained by hydrogenation of vegetable oil.

The wax which is particularly preferably used in the present invention includes an aliphatic hydrocarbon wax. Examples of such an aliphatic hydrocarbon wax include the following. A low molecular weight alkylene polymer obtained by radically polymerizing alkylene under high pressure or by using Ziegler catalyst under low pressure. An alkylene polymer obtained by thermally decomposing a high molecular weight alkylene polymer. A synthetic hydrocarbon wax obtained from a distillation residue of a hydrocarbon obtained by a Arge process from a synthesis gas containing carbon monoxide and hydrogen, and a synthetic hydrocarbon wax obtained by hydrogenating the same. A wax obtained by separating these aliphatic hydrocarbon waxes by the use of press sweating method, solvent method, vacuum distillation, or fractional crystallization method.

Examples of the hydrocarbon as a matrix of the aliphatic hydrocarbon wax include the following. Carbonization synthesized by the reaction of carbon monoxide and hydrogen using a metal oxide catalyst (often two or more multi-component systems) (for example, the gintol method, the hydrocoal method (using a fluidized catalyst bed)) Hydrogen compounds). Hydrocarbons with up to several hundred carbons obtained by the Arge method (using an identified catalyst bed), which yields a lot of waxy hydrocarbons. Hydrocarbons obtained by polymerizing alkylenes such as ethylene with a Ziegler catalyst.
Among such hydrocarbons, in the present invention, straight chain hydrocarbons having few branches and small and long saturation are preferable, and particularly, hydrocarbons synthesized by a method not based on the polymerization of alkylene have a molecular weight distribution. Is also preferable.

Specific examples that can be used include: Viscor (registered trademark) 330-P, 550-P, 660-P, TS-200 (Sanyo Kasei Co., Ltd.); High Wax 400P, 200P, 100P, 410P, 420P, 320P, 220P, 210P, 110P (Mitsui Kagaku Co., Ltd.; Sazol H1, H2, C80, C105, C77 (Sazol Co.); HNP-1, HNP-3, HNP-9, HNP-10, HNP-11, HNP-12 (Nippon Seiwa Co., Ltd.) )), Unilin (registered trademark) 350, 425, 550, 700, Unicid (registered trademark) 350, 425, 550, 700 (Toyo Adre Co., Ltd.); wood wax, beeswax, rice wax, candelilla wax, Carnauba wax (Cerarica NODA, Inc.).

The release agent (wax) may be added at the time of melt-kneading during the production of the toner particles, but it may also be added during the production of the toner resin, and is appropriately selected from existing methods. Further, these releasing agents may be used alone or in combination.
The release agent is preferably added in an amount of 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the toner resin. When it is less than 1 part by mass, the desired releasing effect is difficult to be sufficiently obtained, and when it exceeds 20 parts by mass, the dispersion in the toner particles is poor, and the toner adheres to the electrostatic image carrier, the developing member and the cleaning member. The surface of the member is likely to be contaminated and the toner image is easily deteriorated.

[Toner charge control agent]
A charge control agent can be used in the toner of the present invention to stabilize its triboelectric charging property. The charge control agent, which varies depending on the type and physical properties of other toner particle constituent materials, is generally contained in the toner particles in an amount of 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the resin component. Is preferable, and it is more preferable that the amount is 0.1 part by mass or more and 5.0 parts by mass or less.

As such a charge control agent, one that controls the toner to have a negative charging property and one that controls the toner to have a positive charging property are known. One type or two types of various types are used depending on the type and use of the toner. The above can be used.

The following are examples of controlling the toner to have a negative charging property. Organic metal complex (monoazo metal complex; acetylacetone metal complex); metal complex or metal salt of aromatic hydroxycarboxylic acid or aromatic dicarboxylic acid. In addition, aromatic mono- and polycarboxylic acids and their metal salts and anhydrides; esters and phenol derivatives such as bisphenol can be used to control the toner to be negatively charged. Among these, in particular, a metal complex or a metal salt of an aromatic hydroxycarboxylic acid that can obtain stable charging performance is preferably used.

The following are examples of controlling the toner to be positively charged. Modified products of nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs thereof; onium salts such as phosphonium salts and These lake pigments; triphenylmethane dyes and these lake pigments (as the laking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanine compounds Etc.); Metal salts of higher fatty acids. In the present invention, these can be used alone or in combination of two or more. Of these, charge control agents such as nigrosine compounds and quaternary ammonium salts are particularly preferably used for controlling the toner to be positively charged.

Specific examples include the following. Spiron Black TRH, T-77, T-95, TN-105 (Hodogaya Chemical Co., Ltd.); BONTRON (registered trademark) S-34, S-44, E-84, E-88 (Orient Chemical Industry ( Co., Ltd.); TP-302, TP-415 (Hodogaya Chemical Co., Ltd.); BONTRON (registered trademark) N-01, N-04, N-07, P-51 (Orient Chemical Co., Ltd.); Copy Blue PR (Clariant).
A charge control resin can also be used, and can be used in combination with the above charge control agent.

[External additive for toner]
Further, in the toner of the present invention, it is preferable to externally add fine silica powder to the toner particles in order to improve charge stability, developability, fluidity and durability.
The fine silica powder used in the present invention has a specific surface area of 30 m ² /g or more (particularly 50 m ² /g or more and 400 m ² /g or less) by the BET method by nitrogen adsorption, which gives good results. The fine silica powder is preferably used in an amount of 0.01 part by mass or more and 8.00 parts by mass or less, and more preferably 0.10 part by mass or more and 5.00 parts by mass or less, relative to 100 parts by mass of the toner. The BET specific surface area of the silica fine powder can be calculated by adsorbing nitrogen gas on the surface of the silica fine powder and using the BET multipoint method. Examples of the specific surface area measuring device include Autosorb 1 (manufactured by Yuasa Ionics), GEMINI 2360/2375 (manufactured by Micrometrics), and Tristar 3000 (manufactured by Micrometrics).

In addition, the silica fine powder used in the present invention is preferably treated with various treatment agents for the purpose of hydrophobizing and controlling triboelectrification properties, if necessary. Examples of the treating agent include the following.
Unmodified silicone varnish, various modified silicone varnish, unmodified silicone oil, various modified silicone oil, silane coupling agent, silane compound having functional group, or other organosilicon compound.

Further, other external additives may be added to the toner of the present invention, if necessary. Examples of such external additives include resin auxiliary particles that act as a charging aid, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a release agent at the time of heat roller fixing, a lubricant, and an abrasive. Inorganic fine powder can be used.
Examples of lubricants include polyfluorinated ethylene powder, zinc stearate powder, and polyvinylidene fluoride powder.
Examples of the abrasive include cerium oxide powder, silicon carbide powder, and strontium titanate powder, with strontium titanate powder being preferred.

[Toner manufacturing method]
The method for producing the toner particles of the present invention is not particularly limited, and for example, the following so-called pulverization method can be used. The pulverization method means that the resin components and, if necessary, the toner constituent materials such as a colorant and a release agent are uniformly mixed and then melt-kneaded.The obtained kneaded product is cooled, pulverized, classified, and fluidized This is a method in which the developing agent of the present invention is obtained by thoroughly mixing the quality agent and the like with a mixer such as an FM mixer. As another method, the toner particles can be manufactured by a so-called polymerization method such as an emulsion polymerization method or a suspension polymerization method.

As a method for producing toner particles obtained through at least the melt-kneading step and the pulverizing step, the following method can be used. A resin component and, if necessary, a wax, a colorant, a charge control agent, and other additives are sufficiently mixed with a mixer such as an FM mixer or a ball mill. The mixture is melt-kneaded by using a heat kneader such as a twin-screw kneading extruder, a heating roll, a kneader, and an extruder. At that time, wax, magnetic iron oxide particles and a metal-containing compound may be added. The melt-kneaded product is cooled and solidified, and then pulverized and classified to obtain toner particles.

Further, the toner particles and the external additive can be mixed with a mixer such as an FM mixer to obtain a toner.
The following are mentioned as a mixer. FM mixer (Nippon Coke Industry Co., Ltd.); Supermixer (Kawata Co., Ltd.); Ribocon (Okawara Mfg. Co., Ltd.); Nauta Mixer, Turbulizer, Cyclomix (Hosokawa Micron Co., Ltd.); Spiral Pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.); Ledige mixer (manufactured by Matsubo Co., Ltd.). Examples of the kneader include the following. KRC Kneader (manufactured by Kurimoto Iron Works Co., Ltd.); Bus Co Kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Japan Steel Works, Ltd.) PCM kneader (manufactured by Ikegai Co., Ltd.); three-roll mill, mixing roll mill, kneader (manufactured by Inoue Manufacturing Co., Ltd.); kneedex (manufactured by Nippon Coke Industry Co., Ltd.); MS pressure kneader, nider ruder Moriyama Mfg. Co., Ltd.; Banbury mixer (Kobe Steel Mfg. Co., Ltd.). The crusher includes the following. Counter Jet Mill, Micron Jet, Inomizer (manufactured by Hosokawa Micron Co., Ltd.); IDS type mill, PJM jet crusher (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); Cross Jet Mill (manufactured by Kurimoto Iron Works Co., Ltd.); Ulmax (Manufactured by Nisso Engineering Co., Ltd.); SK Jet O Mill (manufactured by Seishin Enterprise Co., Ltd.); Kliptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Freund Turbo Co., Ltd.); Super Rotor ( Made by Nisshin Engineering Co., Ltd.

Examples of the classifier include the following. Classile, Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (manufactured by Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron Co., Ltd.) ); Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); YM Microcut (manufactured by Yasukawa Shoji Co., Ltd.).

The sieving device used for sieving the coarse particles includes the following. Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonator Sieve, Gyro Shifter (Dekuju Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turbos Cleaner (Freund Turbo Co., Ltd.); Micro Shifter (Makino Sangyo Co., Ltd.); Circular vibrating screen.

FIG. 12 shows a schematic configuration of an example of an image forming apparatus to which the image forming method according to the present invention can be applied.
The developing means 101 contains a magnetic toner 102. The bias applying unit 203 applies a voltage to the charging unit 200. The charging unit 200 charges the image carrier 103, which is a photoconductor. An electrostatic charge image is formed on the image carrier 103 by the exposure light (for example, laser light or light of a halogen lamp) 105. The developing means 101 includes a toner coating blade (for example, elastic blade, magnetic blade, etc.) 108 and a developing sleeve 106. The developing sleeve 106 contains a magnetic field generating means (for example, a magnet) 109.

The electrostatic toner image is developed by the magnetic toner 102 contained in the developing means 101. As the developing method, a regular developing method or a reversal developing method is used. In the developing unit, the bias applying unit 201 applies an alternating bias, a pulse bias and/or a DC bias to the developing sleeve 106 as necessary. A voltage is applied to the transfer unit (for example, transfer roller, transfer belt, etc.) 104 by the bias applying unit 202. When the transfer material P is conveyed and reaches the transfer portion, the transfer means 104 charges the transfer material P while pressing it from the back surface (the side opposite to the photoconductor 103 side) of the transfer material P, so that the toner on the surface of the photoconductor 103 is charged. The image is electrostatically transferred onto the transfer material P. If necessary, the toner image on the photoconductor 103 is transferred to an intermediate transfer member (for example, an intermediate transfer drum, an intermediate transfer belt, etc.) not shown, and the toner image is transferred from the intermediate transfer member to the transfer material P. May be.

The toner image on the transfer material P separated from the photoconductor 103 is heated and pressed by a heating/pressurizing unit (for example, a fixing device or a heating/pressurizing roller fixing device in which a pressing roller is pressed against a fixed heating element through a heat resistant sheet). Etc.) 204 is heated and fixed on the transfer material P. The toner remaining on the image carrier 103 after the transfer step is removed from the surface of the photoconductor 103 by a cleaning unit (for example, a cleaning blade, a cleaning roller, a cleaning brush) 107, if necessary. For the image carrier 103 after cleaning, the process starting from the charging process by the charging means 200 is repeated again.

FIG. 13 is a schematic sectional view of the process cartridge taken out from the image forming apparatus main body. The process cartridge is a cartridge in which the developing means 101, the toner carrier (developing sleeve), that is, the developing means 101, and the image carrier 103 are integrated into a cartridge. The process cartridge is formed so as to be attachable to and detachable from the image forming apparatus main body (for example, a copying machine, a laser beam printer, etc.). Reference numerals in FIG. 13 that are the same as those in FIG. 12 indicate the same members as those described in regard to FIG.

The image carrier used in the present invention has a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer, and the volume resistivity of the undercoat layer is It is preferably 1×10 ¹¹ or more and 1×10 ¹⁶ Ω·cm or less, and contains an electron transporting compound.
At present, an image carrier containing a charge generating substance is mainly used as an image carrier used in a process cartridge or an electrophotographic apparatus. The image carrier generally has a support and a photosensitive layer formed on the support. An undercoat layer may be provided between the support and the photosensitive layer for the purpose of suppressing charge injection from the support side to the photosensitive layer side and suppressing the occurrence of image defects such as black spots. Many.

In recent years, a charge generating substance having a higher sensitivity has been used. However, as the charge-generating substance becomes more sensitive, the amount of generated charge increases, and the charge easily accumulates at the interface between the undercoat layer and the photosensitive layer. The phenomenon becomes remarkable.
In the image forming method using the charging member of the present invention, the image carrier has an undercoat layer having a volume resistivity of 1×10 ¹¹ or more and 1×10 ¹⁶ Ω·cm or less, and contains an electron transporting compound. By doing so, it is easy to suppress the occurrence of image defects such as black spots, which is preferable.

[Image carrier]
Hereinafter, the image carrier applicable to the present invention will be described.
The image carrier is preferably an image carrier having a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer.
The photosensitive layer is preferably a laminated (function separation type) photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance are separated. Further, from the viewpoint of electrophotographic characteristics, the laminated type photosensitive layer is preferably a forward layer type photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

[Support]
As the support, for example, a conductive support made of a metal or alloy such as aluminum, nickel, copper, gold, and iron can be used. Support with a thin film of aluminum, silver, or gold metal formed on an insulating support such as polyester resin, polycarbonate resin, polyimide resin, or glass, or support with a thin film of conductive material such as indium oxide or tin oxide. The body.
The surface of the conductive support may be subjected to an electrochemical treatment such as anodic oxidation, a wet honing treatment, a blast treatment, or a cutting treatment in order to improve electric characteristics and suppress interference fringes.

(Conductive layer)
A conductive layer may be provided between the conductive support and the undercoat layer. The conductive layer is a layer formed by using a conductive layer coating liquid in which conductive particles are dispersed in a resin.
Examples of the conductive particles include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, and metal such as conductive tin oxide and ITO (indium tin oxide). Examples thereof include oxide powder.

Examples of the resin include polyester resin, polycarbonate resin, polyvinyl butyral, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin and alkyd resin.
Examples of the solvent for the conductive layer coating liquid include ether solvents, alcohol solvents, ketone solvents and aromatic hydrocarbon solvents. The thickness of the conductive layer is preferably 0.2 μm or more and 40 μm or less. It is more preferably 1 μm or more and 35 μm or less, further preferably 5 μm or more and 35 μm or less.

[Undercoat layer]
The undercoat layer is provided on the support or on the above-mentioned conductive layer.
The volume resistivity of the undercoat layer is preferably 1×10 ¹¹ Ω·cm or more and 1×10 ¹⁶ Ω·cm or less, and the undercoat layer preferably contains an electron transporting compound.
The electron-transporting compound has a polymerizable functional group and may contain a polymer of a composition containing an electron-transporting substance and a crosslinking agent, or a composition containing the electron-transporting substance and a binder resin. It is more preferable in terms of enhancing the effect of the invention. The polymerizable functional group is either a hydroxy group, a thiol group, an amino group, or a carboxy group.

When the volume resistivity of the undercoat layer is within the above range, the binder resin may contain a small amount of an ionic substance, or the undercoat layer may further contain conductive particles. In that case, the content of the ionic substance and the type of the conductive particles can be appropriately selected so that the volume resistivity falls within the above range.
Examples of the conductive particles include carbon black, acetylene black, metal powders such as aluminum, nickel, iron, nichrome, copper, zinc and silver, conductive tin oxide, and metal oxide powders such as ITO. Can be mentioned.
The content of the electron transporting substance is more preferably 30% by mass or more and 70% by mass or less with respect to the total mass of the composition from the viewpoint of exhibiting the effect of the present invention.

[Electron transport substance]
Examples of the electron-transporting substance include quinone compounds, imide compounds, benzimidazole compounds, and cyclopentadienylidene compounds. The electron transporting substance is preferably an electron transporting substance having a polymerizable functional group. Examples of the polymerizable functional group include a hydroxy group, a thiol group, an amino group, a carboxy group, or a methoxy group. The compounds represented by any of the following formulas (A1) to (A11) are shown below as specific examples of the electron transporting substance.

In formulas (A1) to (A11), R ^{11 to} R ¹⁶ , R ^{21 to} R ³⁰ , R ^{31 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁶⁰ , R ^{61 to} R ⁶⁶ , R ^{71 to} R. ⁷⁸ , R ^{81 to} R ⁹⁰ , R ^{91 to} R ⁹⁸ , R ^{101 to} R ¹¹⁰ , and R ^{111 to} R ¹²⁰ are each independently a monovalent group represented by the following formula (A), a hydrogen atom, or a cyano group. , A nitro group, a halogen atom, an alkoxycarbonyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocycle. One of the carbon atoms in the main chain of the alkyl group may be replaced with O, S, NH or NR ¹²¹ (R ¹²¹ is an alkyl group). The substituent of the substituted alkyl group is an alkyl group, an aryl group, a halogen atom, or an alkoxycarbonyl group. The substituent of the substituted aryl group and the substituent of the substituted heterocyclic group are a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group and an alkoxy group.
Z ²¹ , Z ³¹ , Z ⁴¹ and Z ⁵¹ each independently represent a carbon atom, a nitrogen atom or an oxygen atom. When Z ²¹ is an oxygen atom, R ²⁹ and R ³⁰ are absent, and when Z ²¹ is a nitrogen atom, R ³⁰ is absent. When Z ³¹ is an oxygen atom, R ³⁷ and R ³⁸ are absent, and when Z ³¹ is a nitrogen atom, R ³⁸ is absent. When Z ⁴¹ is an oxygen atom, R ⁴⁷ and R ⁴⁸ are absent, and when Z ⁴¹ is a nitrogen atom, R ⁴⁸ is absent. When Z ⁵¹ is an oxygen atom, R ⁵⁹ and R ⁶⁰ are absent, and when Z ⁵¹ is a nitrogen atom, R ⁶⁰ is absent.

In formula (A), at least one of α, β, and γ is a group having a substituent, and the substituent is selected from the group consisting of a hydroxy group, a thiol group, an amino group, a carboxy group, and a methoxy group. It is at least one type of group. l and m are each independently 0 or 1, and the sum of l and m is 0 or more and 2 or less.

α is an alkylene group having 1 to 6 carbon atoms in the main chain, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms, and a main chain substituted with benzyl group. An alkylene group having 1 to 6 atoms, an alkylene group having 1 to 6 atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 6 atoms in the main chain substituted with a phenyl group is shown. .. At least one of R ^{11 to} R ¹⁶ , at least one of R ^{21 to} R ³⁰ , at least one of R ^{31 to} R ³⁸ , at least one of R ^{41 to} R ⁴⁸ , at least one of R ^{51 to} R ⁶⁰ ; At least one of R ^{61 to} R ⁶⁶ , at least one of R ^{71 to} R ⁷⁸ , at least one of R ^{81 to} R ⁹⁰ , at least one of R ^{91 to} R ⁹⁸ , at least one of R ^{101 to} R ¹¹⁰ ; At least one of R ^{111 to} R ¹²⁰ has a monovalent group represented by formula (A). These groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group and a carboxy group as a substituent. One of the carbon atoms in the main chain of the alkylene group may be replaced with O, S or NR ¹²² (wherein R ¹²² represents a hydrogen atom or an alkyl group).

β represents a phenylene group, an alkyl-substituted phenylene group having 1 to 6 carbon atoms, a nitro-substituted phenylene group, a halogen group-substituted phenylene group, or an alkoxy group-substituted phenylene group. These groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, a carboxy group and a methoxy group as a substituent.

γ represents a hydrogen atom, an alkyl group having 1 to 6 atoms in the main chain, or an alkyl group having 1 to 6 atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms. These groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, a carboxy group and a methoxy group as a substituent. One of the carbon atoms in the main chain of the alkyl group may be replaced with O or S or NR ¹²³ (in the formula, R ¹²³ represents a hydrogen atom or an alkyl group).

Among the electron-transporting substances represented by any of the above formulas (A1) to (A11), at least one of R ^{11 to} R ¹⁶ , at least one of R ^{21 to} R ³⁰ , and at least 1 of R ^{31 to} R ³⁸ . At least one of R ^{41 to} R ⁴⁸ , at least one of R ^{51 to} R ⁶⁰ , at least one of R ^{61 to} R ⁶⁶ , at least one of R ^{71 to} R ⁷⁸ , and at least one of R ^{81 to} R ⁹⁰ . At least one of R ^{91 to} R ⁹⁸ , at least one of R ^{101 to} R ¹¹⁰ , and at least one of R ^{111 to} R ¹²⁰ has an electron-transporting substance having a monovalent group represented by the formula (A). Is more preferable.

Specific examples of the electron transporting substance having a polymerizable functional group are shown below. In the table, Aa is represented by the same structural formula as A, and specific examples of the monovalent group are shown in the columns of A and Aa. In the table, when γ is “−”, it indicates a hydrogen atom, and the hydrogen atom of the γ is included in the structure shown in the column of α or β and displayed.

t-Bu represents a tert-butyl group.

Derivatives having any of the structures (A2) to (A6) and (A9) (derivatives of electron-transporting substances) are Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd., and Johnson Matthey Japan Inc. It can be purchased from the company. The derivative having the structure of (A1) can be synthesized by the reaction of a naphthalenetetracarboxylic dianhydride, which can be purchased from Tokyo Chemical Industry Co., Ltd. or Johnson Matthey Japan Inc., with a monoamine derivative.
The derivative having the structure of (A7) can be synthesized using a phenol derivative which can be purchased from Tokyo Chemical Industry Co., Ltd. or Sigma-Aldrich Japan Co., Ltd. as a raw material. The derivative having the structure of (A8) can be synthesized by a reaction between a perylenetetracarboxylic dianhydride, which can be purchased from Tokyo Chemical Industry Co., Ltd. and Sigma-Aldrich Japan Co., Ltd., and a monoamine derivative.
The derivative having the structure of (A10) is obtained by oxidizing a phenol derivative having a hydrazone structure with an appropriate oxidizing agent such as potassium permanganate in an organic solvent by using a known synthesis method described in, for example, Japanese Patent No. 3717320. Can be synthesized. Derivatives having the structure of (A11) include naphthalenetetracarboxylic dianhydride, monoamine derivative, and hydrazine which can be purchased from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd. or Johnson Matthey Japan Inc. It can be synthesized by the reaction.

The compound represented by any of (A1) to (A11) has a polymerizable functional group (hydroxy group, thiol group, amino group, carboxy group and methoxy group) capable of being polymerized with the crosslinking agent. As a method for synthesizing the compound represented by any of (A1) to (A11) by introducing a polymerizable functional group into the derivative having the structure of any of (A1) to (A11), the following method is used. Are listed. For example, there is a method in which a derivative having any of the structures (A1) to (A11) is synthesized and then the polymerizable functional group is directly introduced. Further, there is a method of introducing a structure having a polymerizable functional group or a functional group which can be a precursor of the polymerizable functional group. As a method to be described later, based on the halide of the derivative having any of the structures (A1) to (A11), for example, a cross coupling reaction using a palladium catalyst and a base is used to obtain an aryl group having a functional group. There is a way to introduce. In addition, a method of introducing an alkyl group having a functional group using a cross-coupling reaction using a FeCl ₃ catalyst and a base based on a halide of a derivative having any of the structures (A1) to (A11) is available. is there. Further, there is a method of introducing a hydroxyalkyl group or a carboxy group by reacting an epoxy compound or CO ₂ after a lithiation with a halide of a derivative having any of the structures (A1) to (A11). ..
From the viewpoint of having high solvent resistance and forming a strong crosslinked structure, it is preferable that the electron transporting substance having a polymerizable functional group has two or more polymerizable functional groups in the same molecule.

[Crosslinking agent]
Next, the crosslinking agent having a polymerizable functional group will be described.
As the cross-linking agent, a compound usually used as a cross-linking agent can be used. Specifically, compounds and the like described in "Crosslinking Agent Handbook" edited by Shinzo Yamashita and Tosuke Kaneko, published by Taiseisha Co., Ltd. (1981) can be used.
The crosslinking agent used in the present invention is preferably an isocyanate compound or an amino compound.
The isocyanate compound used in the present invention preferably has 3 to 6 isocyanate groups or blocked isocyanate groups. For example, triisocyanate benzene, triisocyanate methylbenzene, triphenylmethane triisocyanate, lysine triisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate diphenylmethane diisocyanate, isophorone diisocyanate, xylylene diisocyanate, 2,2 ,4-trimethylhexamethylene diisocyanate, methyl-2,6-diisocyanate hexanoate, norbornane diisocyanate, and other isocyanurate modified products, biuret modified products, allophanate modified products, and adduct modified products with trimethylolpropane and pentaerythritol Various modified forms such as
Among them, isocyanurate modified products and adduct modified products are more preferred.

The blocked isocyanate group takes the form of -NHCOX (X is a protecting group). X may be any protective group that can be introduced into an isocyanate group, but groups represented by the following (H1) to (H6) are more preferable.

Specific examples of the isocyanate compound are shown in Tables 12-1 and 12-2 below.

The undercoat layer of the present invention may further contain a thermoplastic resin having a polymerizable functional group. As the thermoplastic resin having a polymerizable functional group, a thermoplastic resin having a structural unit represented by the following formula (D) is preferable.

In formula (D), R ¹ represents a hydrogen atom or an alkyl group. Y ¹ represents a single bond, an alkylene group or a phenylene group. W ¹ represents a hydroxy group, a thiol group, an amino group, a carboxy group, or a methoxy group.
Examples of the thermoplastic resin having the structural unit represented by the formula (D) include acetal resin, polyolefin resin, polyester resin, polyether resin, and polyamide resin. The structural unit represented by the above formula (D) may be contained in the characteristic structure shown below or may be contained in a structure other than the characteristic structure. The characteristic structures are shown in (E-1) to (E-5) below. (E-1) is a structural unit of an acetal resin. (E-2) is a structural unit of a polyolefin resin. (E-3) is a structural unit of polyester resin. (E-4) is a structural unit of polyether resin. (E-5) is a structural unit of polyamide resin.

In the above formula, R ^{201 to} R ²¹⁰ each independently represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. When R ²⁰¹ is C ₃ H ₈ (butyl group), it is shown as butyral.
The resin having the structural unit represented by the formula (D) (hereinafter, also referred to as resin D) is obtained, for example, by the following method. A monomer having a polymerizable functional group (hydroxy group, thiol group, amino group, carboxy group, or methoxy group) that can be purchased from Sigma-Aldrich Japan Co., Ltd. or Tokyo Chemical Industry Co., Ltd. is polymerized.

Further, the resin D can be generally purchased. Examples of resins that can be purchased include the following. Polyether polyol resin such as AQD-457, AQD-473 manufactured by Nippon Polyurethane Industry Co., Ltd., Sannix GP-400, GP-700 manufactured by Sanyo Kasei Co., Ltd., Phthalkid W2343, DIC manufactured by Hitachi Chemical Co., Ltd. Watersol S-118, CD-520, Beckolite M-6402-50, M-6201-40IM, Harima Chemicals Haridip WH-1188, Nippon Yupica ES3604, ES6538 and other polyesters. Polyol-based resins, polyacryl polyol-based resins such as DIC KK, Bernock WE-300 and WE-304, polyvinyl alcohol-based resins such as Kuraray Kuraray Poval PVA-203, and Sekisui Chemical Co., Ltd. Polyvinyl acetal resins such as BX-1 and BM-1, polyamide resins such as Torayzin FS-350 manufactured by Nagase Chemtex Co., Ltd., AQUARIC manufactured by Nippon Shokubai Co., Ltd., Finelex SG2000 manufactured by Leadshi Co., Ltd. Carboxy group-containing resins, polyamine resins such as DIC's laccamide, and polythiol resins such as Toray's QE-340M. Among these, polyvinyl acetal resins and polyester polyol resins are more preferable from the viewpoint of polymerizability and uniformity of the electron transport layer.

The weight average molecular weight (Mw) of the resin D is more preferably in the range of 5,000 to 400,000.
Examples of the method for quantifying the polymerizable functional group in the resin include the following. Carboxyl group titration with potassium hydroxide, amino group titration with sodium nitrite, hydroxyl group titration with acetic anhydride and potassium hydroxide, 5,5'-dithiobis(2-nitrobenzoic acid) Titration of thiol groups. Further, a calibration curve method obtained from the IR spectrum of the sample in which the introduction ratio of the polymerizable functional group is changed can be mentioned.
Table 13 below shows specific examples of the resin D.

The thickness of the undercoat layer is preferably 0.3 μm or more and 15 μm or less, more preferably 0.5 μm or more and 5.0 μm or less.

[Charge generation layer]
A charge generation layer is formed on the photosensitive layer.
Examples of the charge generating substance include azo pigments, perylene pigments, anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyrantrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, indigo derivatives, thioindigo derivatives, phthalocyanine pigments, and bisbenzimidazole. Examples include derivatives. Among these, azo pigments and phthalocyanine pigments are preferable. Among the phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine are preferable.

Examples of the binder resin used in the charge generation layer include the following. Polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride and trifluoroethylene, polyvinyl alcohol resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polysulfone resin , Polyphenylene oxide resin, polyurethane resin, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin. Among these, polyester resin, polycarbonate resin, and polyvinyl acetal resin are preferable, and polyvinyl acetal is more preferable.

The charge generation layer is preferably formed by forming a coating film of a charge generation layer coating liquid obtained by dispersing the charge generation substance together with a binder resin and a solvent, and drying the obtained coating film. Further, the charge generation layer may be a vapor deposition film of a charge generation substance.
In the charge generation layer, the mass ratio of the charge generation substance and the binder resin (charge generation substance/binder resin) is preferably in the range of 10/1 to 1/10, and 5/1 to 1/5. The range is more preferable. Examples of the solvent used for the charge generation layer coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents and aromatic hydrocarbon solvents.
The thickness of the charge generation layer is preferably 0.05 μm or more and 5 μm or less.

[Hole transport layer]
A hole transport layer is formed on the charge generation layer.
Examples of the hole transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, benzidine compounds, triarylamine compounds, and triphenylamine. Alternatively, the hole-transporting substance may also include a polymer having a group derived from these compounds in its main chain or side chain. Among these, triarylamine compounds, benzidine compounds, and styryl compounds are preferable.

Examples of the binder resin used in the hole transport layer include polyester resin, polycarbonate resin, polymethacrylic acid ester resin, polyarylate resin, polysulfone resin, and polystyrene resin. Among these, polycarbonate resin and polyarylate resin are preferable. The weight average molecular weight (Mw) of these is preferably 10,000 to 300,000.

In the hole transport layer, the mass ratio of the hole transport material and the binder resin (hole transport material/binder resin) is preferably 10/5 to 5/10, more preferably 10/8 to 6/10. ..
The film thickness of the hole transport layer is preferably 3 μm or more and 40 μm or less, and more preferably 5 μm or more and 16 μm or less. Examples of the solvent used in the hole transport layer coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents and aromatic hydrocarbon solvents.

Further, a protective layer may be formed on the hole transport layer. The protective layer preferably contains conductive particles or a charge transport material and a binder resin. Further, the protective layer may further contain an additive such as a lubricant. Further, the binder resin itself may have conductivity or charge transportability, and in that case, the protective layer may not contain conductive particles or charge transport substance other than the binder resin. The binder resin of the protective layer may be a thermoplastic resin or a curable resin obtained by polymerization with heat, light or radiation (electron beam). The thickness of the protective layer is preferably 1 μm or more and 10 μm or less.

As a method for forming each of the above layers, a coating solution obtained by dissolving and/or dispersing the material forming each layer in a solvent is applied to form a coating film, and the obtained coating film is dried and/or cured. The method of forming by doing is preferable. Examples of the method of applying the coating solution include a dip coating method (dipping coating method), a spray coating method, a curtain coating method, and a spin coating method.
Next, a method for measuring each physical property according to the present invention will be described.

<Calculation of luminance due to conductivity>
A method for evaluating the charging member based on the brightness due to the above-described conductivity will be described below.
FIG. 11 (11a) is a schematic diagram showing an embodiment of a scanning electron microscope for calculating the luminance due to the conductivity of the uneven portion.

The power source 93 applies a positive potential to the conductive substrate 92. A predetermined potential is applied to the conductive substrate 92, and in that state, the electron beam 91 is irradiated with an accelerating voltage that penetrates from the surface of the charging member to each point on the surface only near the surface. The irradiation position of the electron beam 91 continuously scans the XY plane (Y is a direction perpendicular to the paper surface) of FIG. 11 (11 a ). By irradiating the surface of the charging member with the electron beam 91, secondary electrons are emitted. The magnitude of the measured amount of secondary electrons is converted into contrast information, which is then associated with the electron beam irradiation position to form an image, and a secondary electron image is obtained.

The amount of secondary electrons generated from the surface of the charging member by the electron beam irradiation at this time is as follows depending on the conductivity of the electron beam irradiated portion when a positive potential is applied to the conductive substrate 92 by the power source 93. [1] or [2] phenomenon occurs.
[1] When the conductivity of the electron beam irradiated portion is high (FIG. 11 (11c))
Secondary electrons generated by electron beam irradiation are attracted to the side of the conductive substrate having a positive potential, and the amount of secondary electrons detected by the detector is reduced.
[2] When the conductivity of the electron beam irradiated portion is low (FIG. 11 (11b))
The attraction of the secondary electrons to the side of the conductive substrate having a positive potential is suppressed, and the amount of secondary electrons detected by the detector is larger than that in [1] above.

From the above, the contrast converted from the magnitude of the measured amount of secondary electrons varies depending on the conductivity of the electron beam irradiated part, and the conductivity of the electron beam irradiated part can be estimated from the brightness of the secondary electron image. Becomes Specifically, as described above, the smaller the brightness, the smaller the amount of secondary electrons detected by the detector, that is, the higher the conductivity at that site. The higher the brightness, the larger the amount of secondary electrons detected, that is, the lower the conductivity of the site.

In the present invention, using a scanning electron microscope capable of obtaining a contrast image due to the above conductivity,
The brightness K1 of the convex portion 18 of the bowl on the surface of the charging member of FIG.
The brightness K2 of the bottom of the recess 17 of the bowl, and
The brightness K3 of the binder 12 exposed on the surface is calculated.
In obtaining a contrast image due to the conductivity, it is useful to apply a voltage to the object to be observed, and the scanning electron microscope is observed by a device modified so that a DC power supply can be connected via a vacuum feedthrough. Is preferably performed. The term "vacuum feedthrough" refers to a vacuum attached to a vacuum wall that shields the vacuum state from the atmosphere in order to control the transport of electrical signals, physical movements, fluids, etc. into the equipment that maintains the vacuum state. It is a part.

The observation conditions will be described below. The positive potential applied to the conductive substrate needs to be in the range of 50 to 100V. This is because the voltage generally applied to the charging member during image formation is within the above range and the contrast thereof correlates with the output image.

The acceleration voltage of the electron beam needs to be 1 kV. When the accelerating voltage is lower than 1 kV, most of the electrons cannot pass through the bowl-shaped resin particles 11 of FIG. 2(2a), and the bowl-shaped resin particles and the binder portion located immediately below the resin particles are not included. The brightness K2 due to the conductivity cannot be calculated accurately. When the accelerating voltage of the electron beam is higher than 1 kV, most of the electrons penetrate to the binder portion directly below the bowl-shaped resin particles, and the bowl-shaped resin particles and the binder portion located immediately below the bowl-shaped resin particles are included. It is not possible to accurately calculate the value of the brightness K2 due to the conductivity.

In accurately calculating the values of the brightnesses K1 to K3, the contrast and brightness of the scanning electron microscope have a great influence. Therefore, in order to accurately calculate the values of the brightnesses K1 to K3, in the present invention, it is preferable that the contrast is 45% or more and 55% or less and the brightness is 25% or more and 30% or less, and the contrast is 50% and the brightness is 28%. Is more preferable.

An example of specific conditions will be shown below.
A scanning electron microscope (ULTRA plus, manufactured by Carl Zeiss) was modified so that a DC power source (P4K-80H, manufactured by Matsusada Precision) could be connected via a vacuum feedthrough, and observation was performed. The observation was performed by applying a potential of 75 V to the conductive substrate and irradiating the surface of the charging member with an electron beam under the condition of an accelerating voltage of 1.0 kV, working distance (WD) 2.8 mm, magnification 2000 times, contrast 50%, Brightness was 28%. Then, a secondary electron image was obtained by observing a region in which both the bowl-shaped concave portion derived from the resin particles and the binder on the surface of the charging member can be observed.

In the secondary electron image, the brightness K1, brightness K2, and brightness K3 were calculated using image analysis software (ImageProPlus (registered trademark): manufactured by Adobe System). For each luminance, the average luminance value of all pixels within a range of 10 μm×10 μm was measured at 4 points, and the average value of the average luminance values at these 4 points was used.

<Measurement of surface roughness Rzjis of charging member and average unevenness interval Sm>
The surface roughness was measured according to JIS B 0601-1994 surface roughness standard, and was measured using a surface roughness measuring instrument (trade name: SE-3500, manufactured by Kosaka Laboratory Ltd.). Rzjis and Sm were measured at six randomly selected positions of the charging member, and their average values were used. The cutoff value is 0.8 mm and the evaluation length is 8 mm.

<Shape measurement of bowl-shaped resin particles of charging member>
The measurement points are the central part in the longitudinal direction of the charging member, the position 45 mm apart from the central part in the direction of both ends, and the position 90 mm apart from the central part in the direction of both ends in the longitudinal direction. There were a total of 10 positions of two positions (phase 0° and 180°) in the circumferential direction of the member. At each of these measurement points, the conductive resin layer was cut out over 500 μm using a focused ion beam processing observation device (trade name: FB-2000C, manufactured by Hitachi, Ltd.) in 20 nm increments, and a cross-sectional image was taken. did. Then, the obtained cross-sectional images were combined to calculate a three-dimensional image of the bowl-shaped resin particles. From the three-dimensional image, the "maximum diameter" 55 as shown in FIG. 6 and the "minimum diameter of the opening" 63 shown in FIG. 7 were calculated. Further, the "difference between the outer diameter and the inner diameter", that is, the "shell thickness" of the bowl-shaped resin particles was calculated from any of the five points of the bowl-shaped resin particles from the three-dimensional image. Such measurement is performed for 10 resin particles in the visual field, and the average value of the obtained 100 measured values is calculated, and these are respectively calculated as “maximum diameter”, “minimum diameter of opening” and “shell”. Thickness”. When measuring the shell thickness, for each bowl-shaped resin particle, the thickness of the thickest part of the shell is not more than twice the thickness of the thinnest part, that is, the shell thickness is substantially uniform. Was confirmed.

<Measurement of height difference between top of convex portion and bottom of concave portion of charging member surface>
The surface of the charging member was observed with a laser microscope (trade name: LXM5 PASCAL: manufactured by Carl Zeiss) in a visual field of 0.5 mm in length and 0.5 mm in width. Two-dimensional image data was obtained by scanning the laser on the XY plane in the visual field, and the focus was moved in the Z direction, and the above-described scanning was repeated to obtain three-dimensional image data. As a result, first, it was confirmed that there were a concave portion derived from the opening of the bowl-shaped resin particles and a convex portion derived from the edge of the opening of the bowl-shaped resin particles. Further, the height difference 54 between the apex of the convex portion and the bottom of the concave portion was calculated. Such an operation was performed for two bowl-shaped resin particles within the field of view. Then, the same measurement was performed at 50 points in the longitudinal direction of the charging member, and the average value of the obtained 100 resin particles in total was calculated, and this value was defined as “height difference”.

<Measurement of electric resistance of charging member>
FIG. 4 shows a measuring device for measuring the electric resistance value of the charging member. A load was applied to both ends of the conductive substrate 33 by the bearings 32, and the charging member 34 was brought into contact with the cylindrical metal 31 having the same curvature as that of the image carrier (not shown) in parallel. In this state, a cylindrical metal 31 was rotated by a motor (not shown), and a DC voltage of -200V was applied from a stabilizing power supply 35 while the charging member 34 in contact with the motor 31 was driven to rotate. The current flowing at this time was measured by the ammeter 36, and the electric resistance value of the charging member 34 was calculated. The load was 4.9 N each, the metal column 31 had a diameter of 30 mm, and the metal column 31 rotated at a peripheral speed of 45 mm/sec. In the measurement, the charging member 34 was allowed to stand for 24 hours or more in an environment having a temperature of 23° C. and a relative humidity of 50%, and the measurement was performed using a measuring device placed in the same environment.

<Measurement of volume average particle size of resin particles of charging member>
The volume average particle size of the resin particles of the charging member was measured with a Coulter LS-230 type particle size distribution meter (trade name, manufactured by Beckman Coulter, Inc.) which is a laser diffraction type particle size distribution meter. A water-based module was used for the measurement, and pure water was used as a measurement solvent. The inside of the measurement system of the particle size distribution meter was washed with pure water for about 5 minutes, 10 mg to 25 mg of sodium sulfite was added to the measurement system as an antifoaming agent, and the background function was executed. Next, 3 to 4 drops of the surfactant were added to 50 mL of pure water, and 1 mg to 25 mg of the measurement sample was further added. The aqueous solution in which the sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for 1 minute to 3 minutes to prepare a test sample solution. The test sample solution is gradually added to the measurement system of the measurement device so that the PIDS (Polarization Intensity Differential Scattering) on the screen of the device is 45% or more and 55% or less. The measurement was performed by adjusting the sample concentration. The volume average particle diameter was calculated from the obtained volume distribution.

<Method of measuring saturation magnetization of toner>
The saturation magnetization ([sigma]s) of the toner of the present invention is measured with a vibrating magnetometer VSM P-1-10 (manufactured by Toei Industry Co., Ltd.) at room temperature of 25[deg.] C. under an external magnetic field of 795.8 kA/m. To do. The reason why the external magnetic field is measured at 795.8 kA/m is that the relationship between the state of the developing sleeve-like spikes and the saturation magnetization of the toner is most prominent.

<Method of measuring dielectric constant of toner>
About 1 g of the toner is weighed, and a load of 20 kPa is applied for 1 minute to form a disc-shaped measurement sample having a diameter of 25 mm and a thickness of 1.5±0.5 mm.
This measurement sample is attached to ARES (manufactured by TA Instruments) equipped with a dielectric constant measuring jig (electrode) having a diameter of 25 mm. Using a 4284A precision LCR meter (manufactured by Hewlett-Packard Co.) at a measurement temperature of 40° C. and a load of 120 g/cm ² , a dielectric constant ε was obtained from the measured value of the complex dielectric constant at 10 kHz and a temperature of 40° C. 'Is calculated.
In the present invention, the conditions for measuring the dielectric constant are a frequency of 10 kHz and a temperature of 40° C., because the conditions permit effective and stable evaluation of the difference in the dielectric constant of the toner.

<Method of measuring average particle diameter (D1) and shape of primary particles of magnetic particles>
In the present invention, the average particle diameter (D1) and shape of the primary particles of the magnetic particles were measured and observed by a scanning electron microscope (JSM-6830F manufactured by JEOL Ltd.). The average particle diameter (D1) of the primary particles of the magnetic particles is obtained by observing the magnetic particles at a magnification of 30,000, measuring the particle diameter of 100 arbitrary magnetic particles, and measuring the average value of the measurement results of 100 particle diameters. The average particle diameter (D1) of the primary particles of the magnetic particles in the present invention was used.
When measuring the average particle diameter (D1) and shape of the primary particles of the magnetic particles in the toner, the toner as a sample is solidified with an epoxy resin, and then the solidified product is sliced with a slicer such as a microtome into thin slices. The toner particles were used for photography.

<Method of measuring height of convex portion of magnetic particles>
The convex portion of the above-mentioned magnetic particles is composed of one or more fine particles of iron-containing oxide. As shown in FIG. 14 described later, when the coated magnetic particles are observed with a TEM, the protrusions are observed with a size of about several nm.
Specifically, the size is 1 nm or more and 40 nm or less, and particularly 7 nm or more and 20 nm or less. The size of the protrusion means the height of protrusion from the base surface of the coating layer when the coated magnetic particles are observed by TEM. The protrusions may be present on the surface of the coating layer without any gaps, or the base surface of the coating layer (that is, the reference plane on which the protrusions rise) may be present so sparsely as to be observed by TEM. Good.
The size of the protrusions is obtained by observing the coated magnetic particles with a TEM and targeting 15 or more protrusions, as shown in FIG. 15, from the base surface 1503 of the coating layer 1502 covering the core particles 1501 to the apex of the protrusions 1504. It is obtained by measuring the height h up to and arithmetically averaging the measured values.

<Method of measuring presence or absence of convex portion of magnetic particles>
The presence or absence of a convex portion on the surface of the magnetic particles was observed by a transmission electron microscope (JEM-2100 manufactured by JEOL Ltd.), and it was determined whether or not there was a protruding portion with the base surface of the flat portion of the octahedron as a reference.
When measuring the height of the convex portion on the surface of the magnetic particles in the toner, the toner as a sample is solidified with an epoxy resin, and then the solidified product is sliced with a slicer such as a microtome to obtain thin toner particles. I took a picture of.

<Method for analyzing element of coating layer of magnetic particles>
The ratio of elements in the coating layer of the magnetic particles is 50% by mass of diluted sulfuric acid at 5° C., the magnetic particles of the present invention are suspended to obtain a measurement solution, and then a part of the measurement solution is sampled at regular intervals. .. The concentration of silicon, aluminum and iron contained in the filtrate obtained by filtering this with a membrane filter is measured and determined by quantifying with an ICP emission spectroscopy analyzer. In this measurement, the amount of iron dissolved until silicon and aluminum are no longer detected is taken as the amount of iron in the coating layer.

<Method for measuring softening point Tm of binder resin for toner>
The softening point Tm of the binder resin is measured as follows. The softening point of the resin is measured using a constant-load extrusion type capillary rheometer "Flow characteristic evaluation device Flow tester CFT-500D" (manufactured by Shimadzu Corporation) according to the manual attached to the device. With this device, while applying a constant load from the top of the measurement sample by the piston, the temperature of the measurement sample filled in the cylinder is raised and melted, and the melted measurement sample is extruded from the die at the bottom of the cylinder. It is possible to obtain a flow curve showing the relationship between temperature and temperature.

In the present invention, the "melting temperature in the 1/2 method" described in the manual attached to the "flow characteristic evaluation device Flow tester CFT-500D" is defined as the softening point. The melting temperature in the 1/2 method is calculated as follows. First, 1/2 of the difference between the piston drop amount Smax at the time when the outflow ends and the piston drop amount Smin at the time when the outflow starts is obtained (this is X. X=(Smax-Smin)/ 2). The temperature of the flow curve when the piston drop amount is the sum of X and Smin in the flow curve is the melting temperature Tm in the 1/2 method.

As a measurement sample, about 1.0 g of a sample was compression-molded under a 25° C. environment for about 60 seconds at about 10 MPa using a tablet molding compressor (for example, NT-100H, manufactured by NPA System Co., Ltd.), A cylinder having a diameter of about 8 mm is used.
The measurement conditions of CFT-500D are as follows.
Test mode: Temperature rising method start temperature: 50°C
Ultimate temperature: 200℃
Measurement interval: 1.0°C
Temperature rising rate: 4.0°C/min Piston cross-sectional area: 1.000 cm ²
Test load (piston load): 10.0 kgf (0.9807 MPa)
Preheating time: 300 seconds Diameter of die hole: 1.0mm
Die length: 1.0mm

<Method for measuring glass transition temperature (Tg) of binder resin for toner>
The glass transition temperature (Tg) of the binder resin is measured using a differential scanning calorimeter (DSC), MDSC-2920 (manufactured by TA Instruments) in accordance with ASTM D3418-82 at room temperature and normal humidity. As a measurement sample, a precisely weighed binder resin of about 3 mg is used. Put this in an aluminum pan and use an empty aluminum pan as a reference. The measurement temperature range is set to 30° C. or higher and 200° C. or lower, the temperature is once raised from 30° C. to 200° C. at a heating rate of 10° C./min, and then the temperature is lowered from 200° C. to 30° C. at a temperature lowering rate of 10° C./min. Then, the temperature is raised to 200° C. at a heating rate of 10° C./min. In the DSC curve obtained in the second heating process, the intersection point of the line at the midpoint of the baseline before and after the specific heat change and the differential heat curve is taken as the glass transition temperature Tg of the resin.

<Method for measuring the weight average particle diameter (D4) of toner>
The weight average particle diameter (D4) of the toner is calculated as follows. As a measuring device, a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.) equipped with a 100 μm aperture tube by a pore electrical resistance method is used. For setting the measurement conditions and analyzing the measurement data, the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.) is used. The measurement is performed with the number of effective measurement channels of 25,000.

The electrolytic aqueous solution used for the measurement may be prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.). ..
Before the measurement and analysis, the dedicated software was set as follows.
On the "Change standard measurement method (SOM)" screen of the dedicated software, set the total count number in the control mode to 50,000 particles, set the number of measurements once, and set the Kd value to "standard particles 10.0 μm" (Beckman Coulter). (Manufactured by Co., Ltd.) is used to set the value obtained. The threshold and noise level are automatically set by pressing the “Threshold/noise level measurement button”. Further, the current is set to 1600 μA, the gain is set to 2, and the electrolytic solution is set to ISOTON II, and a check is put in “Flash of aperture tube after measurement”.
On the "pulse-to-particle size conversion setting" screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm to 60 μm.
The specific measuring method is as follows.

(1) About 200 mL of the electrolytic aqueous solution is put in a glass 250 mL round-bottom beaker dedicated to Multisizer 3, set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rotations/second. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flush" function of the dedicated software.

(2) About 30 mL of the electrolytic aqueous solution is put into a 100 mL flat-bottom beaker made of glass. In this, as a dispersant, "Contaminone N" (a nonionic surfactant, anionic surfactant, a 10 mass% aqueous solution of a neutral detergent for washing precision measuring instruments of pH 7 comprising an organic builder, Wako Pure Chemical Industries, Ltd. )) is diluted with ion-exchanged water to about 3 times by mass, and about 0.3 mL of a diluted solution is added.

(3) An ultrasonic disperser "Ultrasonic Dispersion System Tetra 150" (manufactured by Nikkaki Bios Co., Ltd.) having an electric output of 120 W is prepared by incorporating two oscillators having an oscillating frequency of 50 kHz with phases shifted by 180 degrees. .. About 3.3 L of ion-exchanged water is put in the water tank of the ultrasonic disperser, and about 2 mL of Contaminone N is added to this water tank.

(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker becomes maximum.

(5) About 10 mg of toner is added little by little to the electrolytic aqueous solution in a state where the electrolytic aqueous solution in the beaker of the above (4) is irradiated with ultrasonic waves and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10°C or higher and 40°C or lower.

(6) Using a pipette, drop the toner-dispersed aqueous electrolyte solution of (5) into the round-bottom beaker of (1) installed in the sample stand, and adjust so that the measured concentration is about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.

(7) The measurement data is analyzed by the dedicated software attached to the apparatus to calculate the weight average particle diameter (D4). The “average diameter” on the “Analysis/volume statistical value (arithmetic mean)” screen when the graph/volume% is set by the dedicated software is the weight average particle diameter (D4).

Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples. In the following Examples and Comparative Examples, all parts and% are based on mass unless otherwise specified.
<Production Example of Resin Particles (A-1) for Charging Member>
An aqueous mixed solution containing 4000 parts by mass of ion-exchanged water, 9 parts by mass of colloidal silica as a dispersion stabilizer, and 0.15 parts by mass of polyvinylpyrrolidone was prepared. Next, 50 parts by mass of acrylonitrile, 45 parts by mass of methacrylonitrile, and 5 parts by mass of methyl methacrylate as a polymerizable monomer, 12.5 parts by mass of normal hexane as an inclusion substance, and 0 of dicumyl peroxide as a polymerization initiator. An oily mixture consisting of 0.75 parts by mass was prepared. This oily mixed solution was added to the aqueous mixed solution, and 0.4 part by mass of sodium hydroxide was further added to prepare a dispersion liquid.

The obtained dispersion was stirred and mixed using a homogenizer for 3 minutes, charged into a nitrogen-substituted polymerization reaction container, and reacted at 60° C. for 20 hours under stirring at 400 rpm to prepare a reaction product. The obtained reaction product was repeatedly filtered and washed with water, and then dried at 80° C. for 5 hours to prepare resin particles. The resin particles for a charging member (A-1) were obtained by crushing and classifying the resin particles with a sonic classifier. Table 14 shows the physical properties of the resin particles for charging member (A-1).

<Production Example of Charging Member Resin Particles (A-2) to (A-4)>
A method similar to that of the production example of the resin particles (A-1) for the charging member, except that the amount of colloidal silica used, the type and amount of the polymerizable monomer used, and the stirring rotation number during polymerization were changed. Resin particles (A-2) to (A-4) for a charging member were obtained by producing and classifying resin particles by. Table 14 shows the physical properties of each resin particle.

<Production Example of Conductive Rubber Composition for Charging Member (B-1)>
To 100 parts by mass of acrylonitrile butadiene rubber (NBR) (trade name: N230SV, manufactured by JSR Co.), other materials shown in the column of component (1) in Table 15 were added, and the mixture was adjusted to 50° C. in a closed mixer. Kneaded for 15 minutes. To this, the materials shown in the column of component (2) in Table 15 were added. Then, the mixture was kneaded with a two-roll machine cooled to a temperature of 25° C. for 10 minutes to obtain a conductive rubber composition 1. Table 16 shows the composition of the conductive rubber composition 1.

<Production Examples of Conductive Rubber Compositions (B-2) to (B-4) for Charging Member>
A conductive rubber composition for a charging member (B-1) except that the resin particles for a charging member (A-1) are changed to the resin particles for a charging member (A-2) to (A-4) shown in Table 16. Conductive rubber compositions for charging members (B-2) to (B-4) were obtained in the same manner as in the production example of (1).

<Production Example of Charging Member (C-1)>
[1. Conductive substrate]
A thermosetting resin containing 10% by mass of carbon black was applied to a stainless steel substrate having a diameter of 6 mm and a length of 252.5 mm, and the dried product was used as a conductive substrate.

[2. Formation of conductive elastic layer]
Using an extrusion molding apparatus equipped with a crosshead, the conductive substrate was coated with the conductive rubber composition (B-1) for a charging member, which was produced in Production Example 21, in a cylindrical shape on the peripheral surface of the conductive substrate as a central axis. .. The thickness of the coated conductive rubber composition was adjusted to 1.75 mm.

The roller after extrusion was vulcanized in a hot air oven at 160° C. for 1 hour, and then the end of the rubber layer was removed to a length of 224.2 mm to prepare a roller having a preliminary coating layer. The outer peripheral surface of the obtained roller was polished by using a plunge cut type cylindrical polishing machine. A pitrified grindstone was used as the abrasive grains, the abrasive grains were green silicon carbide (GC), and the grain size was 100 mesh. The rotation number of the roller was 350 rpm, and the rotation number of the polishing grindstone was 2050 rpm. The cutting speed was set to 20 mm/min, and the spark-out time (time when the cut was 0 mm) was set to 0 seconds to carry out polishing to prepare a conductive roller having a conductive elastic layer (coating layer). The thickness of the conductive elastic layer was adjusted to 1.5 mm. The crown amount of this roller (the average value of the difference between the outer diameter d1 at the central portion and the outer diameter d2 at positions 90 mm apart from the central portion in the direction of both ends) was 120 μm.

After polishing, a post-heat treatment was performed at 180° C. for 1 hour in an air atmosphere using a hot air oven to obtain a charging member (C-1). This charging member (C-1) had on its surface a conductive resin layer having a convex portion derived from the edge of the opening of the bowl-shaped resin particles and a concave portion derived from the opening of the bowl-shaped resin particles. .. The results of physical property measurement and image evaluation of the obtained charging member (C-1) are shown in Tables 17 and 18.

<Production Example of Charging Members (C-2) to (C-5)>
The charging members (C-2) to (C-5) were prepared in the same manner as in the production example of the charging member (C-1) except that the vulcanization temperature and the heating temperature after polishing were changed to the conditions shown in Table 17. Was produced. Tables 17 and 18 show the results of measuring the physical properties of the charging members (C-2) to (C-5).

<Production Example of Charging Member (C-6), (C-7)>
The charging member (C-1) was used except that the conductive rubber composition for charging member (B-1) was changed to the conductive rubber composition shown in Table 17 and the heating temperature after polishing was changed to the conditions shown in Table 17. The charging members (C-6) and (C-7) were manufactured in the same manner as in the manufacturing example of (1). Tables 17 and 18 show the results of measuring the physical properties of the charging members (C-6) and (C-7).

<Production Example of Charging Member (C-8), (C-9)>
Charging members (C-8) and (C-9) were produced in the same manner as in the production example of the charging member (C-1) except that the heating temperature after polishing was changed to 170°C or 220°C. .. The results of measuring the physical properties of the charging member are shown in Tables 17 and 18.

<Production Example of Charging Member (C-10)>
Charging member (C-1) except that the conductive rubber composition for charging member (B-1) was changed to the conductive rubber composition for charging member (B-4) and the heating temperature after polishing was changed to 190°C. A charging member (C-10) was manufactured in the same manner as in the manufacturing example of (1). The results of measuring the physical properties of the charging member are shown in Tables 17 and 18.

<Production Example of Charging Member (C-11)>
The conductive rubber composition for charging members (B-1) was changed to the conductive rubber composition for charging members (B-4), and the vulcanization temperature and the heating temperature after polishing were changed to the conditions shown in Table 17. A charging member (C-11) was manufactured in the same manner as in the manufacturing example of the charging member (C-1). Tables 17 and 18 show the results of measuring the physical properties of the charging member (C-11).

<Production Example of Charging Member (C-12)>
By performing the steps up to polishing in the same manner as in the production example of the charging member (C-1), a polished conductive roller was produced. Next, graphite powder (UF-G5, Showa Denko KK) was applied as conductive fine particles to the surface of the conductive roller using the current measuring device of FIG. Specifically, the polished conductive roller was brought into contact with the cylindrical metal 31 in parallel with the load by applying a load of 4.9 N to both ends thereof. In this state, a cylindrical metal 31 is rotated at a peripheral speed of 45 mm/sec by a motor (not shown), and the non-woven fabric impregnated with the graphite powder is pressed against the cylindrical metal 31 and a conductive roller which is driven to rotate. It was applied by applying.

In that state, only the outermost surface was re-polished by 10 μm to obtain a charging member (C-12) in which graphite powder was deposited only on the concave portions of the bowl-shaped resin particles. The results of measuring the physical properties of the charging member are shown in Tables 17 and 18.

<Production Example of Charging Member (C-13)>
[Production Example of Resin Particles]
-Terephthalic acid 34.9 parts by mass-1,4-butanediol 32.7 parts by mass-Polyethylene glycol (number average molecular weight 2000) 56.3 parts by mass-Tetrabutyl titanate 0.1 parts by mass-Antioxidant 0.3 Mass part (trade name: Irganox 1010, manufactured by Ciba Geigy)
Was charged into an esterification reaction can and reacted at 220° C. for 2 hours under a nitrogen gas atmosphere.

Then, the reaction solution was transferred to a polymerization vessel, 0.1 part of tetrabutyl titanate was added, and polymerization was carried out at 250° C. under the condition of 0.5 mmHg or less for 3 hours. After the polymerization was completed, the obtained polymer was discharged onto a cooling belt in a gut shape and pelletized to prepare a pelletized polyether ester.

100 parts by mass of the polyether ester obtained above and 200 parts by mass of polyethylene oxide (manufactured by Meisei Chemical Industry Co., Ltd., trade name: R150) were dry blended with a tumbler mixer, and a twin screw extruder was operated at 260° C. Kneading was performed while heating to obtain a mixture. The obtained mixture was cooled to about 150° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyether ester particles. The target polyetherester resin particles were separated by centrifugation and then dried by heating to obtain substantially spherical polyetherester resin particles having an average particle diameter of 10 μm. The volume resistivity of the obtained resin particles was 7.0×10 ⁸ Ω·cm.
The polyethylene oxide used here is incompatible with the polyether ester and is water-soluble. Further, the polyether ester is insoluble in water.

[Preparation of conductive substrate]
A stainless steel mandrel (core metal) having a diameter of 6 mm and a length of 252.5 mm was used as a support. A thermosetting adhesive (trade name: Metalloc U-20, manufactured by Toyo Kagaku Kenkyusho) was applied to this and dried.
Next, the following materials were kneaded for 10 minutes with a closed type mixer adjusted to 50° C. to prepare a raw material compound.
100 parts by mass of epichlorohydrin rubber terpolymer (ethylene oxide (EO)/epichlorohydrin (EP)/allyl glycidyl ether (AGE)=(73 mol%/23 mol%/4 mol%))
Calcium carbonate 60 parts by mass Aliphatic polyester plasticizer 8 parts by mass Zinc stearate 1 part by mass Anti-aging agent 0.5 parts by mass (2-mercaptobenzimidazole (MB))
2 parts by mass of zinc oxide 2 parts by mass of quaternary ammonium salt 5 parts by mass of carbon black (average particle size: 100 nm, volume resistivity: 0.1 Ω·cm)

To this raw material compound, 1% by mass of sulfur (vulcanizing agent), 1% by mass of dibenzothiazyl sulfide (DM) (vulcanization accelerator) and 0.5% by mass with respect to the epichlorohydrin rubber terpolymer. Tetramethylthiuram monosulfide (TS) was added. Then, the mixture was kneaded for 10 minutes with a two-roll machine cooled to 20° C. to obtain an elastic layer compound.

This elastic layer compound was extruded on an adhesive-coated support by an extruder to form a roller having an outer diameter of about 9 mm, and then in an electric oven at 160° C. for 1 hour. Then, vulcanization and curing of the adhesive were performed. Both ends of the rubber were cut off to make the rubber length 228 mm, and then the surface was polished so as to have a roller shape with an outer diameter of 8.5 mm to form an elastic layer on the support. At this time, the amount of crown (difference in outer diameter between the central portion and a position 90 mm away from the central portion) was 120 μm.

[Preparation of conductive composite fine particles]
To 7.0 kg of silica particles (average particle diameter 15 nm, volume resistivity 1.8×10 ¹² Ω·cm) as metal oxide particles, 140 g of methylhydrogenpolysiloxane was added while operating the edge runner. Then, the mixture was stirred for 30 minutes with a linear load of 588 N/cm (60 Kg/cm). The stirring speed at this time was 22 rpm.

Next, 7.0 kg of carbon black particles (average particle diameter 28 nm, volume resistivity 1.0×10 ² Ω·cm, pH=6.5) were added over 10 minutes while operating the edge runner. Furthermore, the mixture was stirred with a linear load of 588 N/cm (60 Kg/cm) for 60 minutes, carbon black was adhered to the methylhydrogenpolysiloxane coating, and then dried at 80° C. for 60 minutes using a dryer to obtain electrical conductivity. The composite fine particles were obtained. The stirring speed at this time was 22 rpm. The obtained conductive composite fine particles had an average particle diameter of 15 nm and a volume resistivity of 2.3×10 ² Ω·cm.

[Preparation of titanium oxide particles]
Needle-shaped rutile-type titanium oxide particles (average particle size 15 nm, length:width=3:1), volume resistivity: 5.2×10 ¹⁰ Ω·cm) 1000 g, isobutyltrimethoxysilane 110 g as surface treatment agent, toluene as solvent A slurry was prepared by blending 3000 g. After mixing this slurry for 30 minutes with a stirrer, it was supplied to a Viscomill in which 80% of the effective internal volume was filled with glass beads having an average particle diameter of 0.8 mm, and a wet crushing treatment was performed at a temperature of 35±5° C. ..

The slurry obtained by the wet crushing treatment was subjected to vacuum distillation (bath temperature: 110° C., product temperature: 30 to 60° C., degree of vacuum: about 100 Torr) using a kneader to remove toluene, and the surface was maintained at 120° C. for 2 hours. The processing agent was baked. The particles after the baking treatment were cooled to room temperature and then pulverized using a pin mill.

[Preparation of paint for surface layer formation]
Methyl isobutyl ketone was added to a caprolactone-modified acrylic polyol solution (trade name: Praxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) to adjust the solid content to 17% by mass. The following materials were added to 411.8 parts by mass of this solution (100 parts by mass of the solid content of the acrylic polyol solution) to prepare a mixed solution.
50 parts by mass of the composite conductive fine particles 30 parts by mass of the titanium oxide particles 0.24 parts by mass of modified dimethyl silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.)
56 parts by mass of a 7:3 mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) butanone oxime blocks.

At this time, the mixture of block HDI and block IPDI was added so that "NCO/OH=1.0". For HDI and IPDI, HDI (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Chemicals Corporation) and IPDI (trade name: Vestanato B1370, manufactured by Degussa) were used.

A 450 mL glass bottle was mixed with 200 parts by mass out of a total of 548.04 parts by mass of the mixed solution and 200 parts by mass of glass beads having an average particle diameter of 0.8 mm as a medium, and dispersed for 72 hours using a paint shaker disperser. .. After the dispersion, 2.72 parts by mass of the resin particles (corresponding to 10 parts by mass with respect to 100 parts by mass of the solid content of the acrylic polyol solution) was added, followed by dispersing for 30 minutes, and then the glass beads were separated by filtration. Then, a coating material for forming a surface layer was obtained.

This coating for forming a surface layer was dip-coated once on a conductive substrate, air-dried at room temperature for 30 minutes or more, then dried for 1 hour by a hot air circulation dryer set at 80° C., and further set at 160° C. The surface layer was formed on the conductive substrate by drying with a hot air circulation dryer for 1 hour. The dipping coating dipping time is 9 seconds, the dipping coating pulling speed is adjusted so that the initial speed is 20 mm/second and the final speed is 2 mm/second, and between 20 mm/second and 2 mm/second, it is linear with time. I changed the speed.

In this way, a charging member (C-13) having a surface layer having protrusions derived from resin particles on the conductive substrate was produced.
The ten-point average roughness (Rzjis) on the surface of the obtained charging member (C-13) was 7.0 (μm), and the low volume efficiency of the surface layer was 7.0×10 ⁸ .

<Production Example of Charging Member (C-14)>
A charging member (C-14) was prepared in the same manner as the charging member (C-13) except that the resin particles were not added in the production example of the charging member (C-13). The ten-point average roughness (Rzjis) on the surface of the obtained charging member (C-14) was 2.1 μm.

<Production Example of Image Carrier (D-1)>
An aluminum cylinder (JIS-A3003) having a diameter of 30 mm was used as a conductive support.
Next, a conductive layer was formed on the support.
For the conductive layer, the following materials were placed in a sand mill using 450 parts of glass beads having a diameter of 0.8 mm and dispersed under the conditions of rotation speed: 2000 rpm, dispersion treatment time: 4.5 hours, cooling water set temperature: 18° C. Treatment was performed to obtain a dispersion.
Titanium oxide (TiO ₂ ) particles coated with oxygen-deficient tin oxide (SnO ₂ ) as metal oxide particles 214 parts Phenolic resin as binder resin (trade name: Praiophen J-325) 132 parts Methanol 40 Part 1-methoxy-2-propanol 58 parts

Glass beads were removed from this dispersion with a mesh (opening: 150 μm). After removing the glass beads, the silicone resin particles as a surface roughening material (Tospearl 120, manufactured by Momentive Co., Ltd.) are used so that the content thereof is 10% by mass relative to the total mass of the metal oxide particles and the binder resin in the dispersion liquid. ) Was added to the dispersion. Further, a silicone oil (SH28PA manufactured by Toray Dow Corning Co., Ltd.) as a leveling agent was added to the dispersion so that the content of the metal oxide particles and the binder resin in the dispersion was 0.01% by mass. Was added to. By stirring this dispersion liquid, a conductive layer coating liquid was prepared.
This conductive layer coating solution was applied onto a support by dip coating, and the resulting coating film was dried and thermoset at 140° C. for 30 minutes to form a conductive layer having a film thickness of 30.2 μm.

Next, an undercoat layer was formed on the conductive layer.
First, the following materials were mixed with 25.0 parts of methanol (manufactured by Kishida Chemical Co., Ltd., special grade) and 6.5 parts of n-butanol (manufactured by Kishida Chemical Co., Ltd., special grade) and dissolved by stirring. To prepare an undercoat layer coating solution.
3.0 parts of electron-transporting compound represented by the following formula (11) Copolymerized nylon resin as binding resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.)
3.5 parts of the undercoat layer coating solution is applied onto the conductive layer by dip coating to form a coating film, and the obtained coating film is dried at a temperature of 120° C. for 20 minutes to obtain a film having a thickness of 1.0 μm Layers were formed.

Next, a charge generation layer was formed on the undercoat layer.
First, the following materials were placed in a sand mill using glass beads having a diameter of 0.8 mm, dispersion treatment was performed under the condition of dispersion treatment time: 3 hours, and then 250 parts of ethyl acetate was added to the charge generation layer. To prepare a coating solution.
Strong peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 16.3°, 18.6°, 25.1° and 28.3° in CuKα characteristic X-ray diffraction. Crystal form of hydroxygallium phthalocyanine crystal (charge generating substance) 10 parts Polyvinyl butyral (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 5 parts Cyclohexanone 250 parts Coating solution for this charge generating layer is an undercoat layer The charge generation layer was formed by dip coating on the surface and drying the obtained coating film at 100° C. for 10 minutes to form a film having a thickness of 0.15 μm.

Next, a hole transport layer was formed on the charge generation layer.
First, the following materials were dissolved in a mixed solvent of 50 parts of dimethoxymethane and 50 parts of o-xylene to prepare a coating solution for hole transport layer.
Compound represented by the following formula (12-1) 4 parts Compound represented by the following formula (12-2) 4 parts Bisphenol Z type polycarbonate (trade name: Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) 10 parts This positive The hole transport layer having a thickness of 15 μm is obtained by dip-coating the hole transport layer coating solution on the charge generation layer to form a coating film, and drying the obtained coating film at a temperature of 120° C. for 40 minutes. Formed.

In this way, an image bearing member was produced in which the conductive support, the conductive layer, the undercoat layer, the charge generating layer and the hole transporting layer were laminated in this order. Further, similarly to the above, the volume resistivity of the undercoat layer was measured by the above-mentioned method in a state where the conductive support, the conductive layer and the undercoat layer were laminated in this order. The measurement results are shown in Table 23.

<Production Example of Image Carrier (D-2)>
The image carrier (D-1) was prepared in the same manner as the image carrier (D-1) except that the preparation of the undercoat layer was changed as follows.
4.0 parts of an electron transporting compound represented by (A-117),
5.5 parts of a cross-linking agent represented by the formula (B1: protecting group H1),
Resin represented by formula (D25) 0.5 part The above material is dissolved in a mixed solvent of 50 parts of THF (tetrahydrofuran) and 50 parts of 1-methoxy-2-propanol, and the mixture is stirred to prepare a coating liquid for undercoat layer. Prepared.

This undercoat layer coating solution is applied onto the conductive layer by dip coating, and the obtained coating film is heated at 160° C. for 40 minutes to evaporate the solvent and cure the coating film to give an undercoating film having a thickness of 0.7 μm. Layers were formed.
The volume resistivity of the undercoat layer was measured by the method described above in the state where the conductive support, the conductive layer and the undercoat layer were laminated in this order. The measurement results are shown in Table 23.

<Production Example of Image Carrier (D-3)>
The image carrier (D-1) was prepared in the same manner as the image carrier (D-1) except that the preparation of the undercoat layer was changed as follows.
4.0 parts of an electron transporting compound represented by the formula (A-107),
5.5 parts of cross-linking agent represented by the formula (B1: protecting group H1) The above materials were dissolved in a mixed solvent of 50 parts of THF and 50 parts of 1-methoxy-2-propanol. Further, 9.0 parts of titanium oxide (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) and 25 parts of glass beads having a diameter of 0.8 mm were added to prepare a mixed solution. This mixed liquid was subjected to a dispersion treatment for 16 hours with a paint shaker, and glass beads were removed to obtain an undercoat layer coating liquid.

This coating liquid for undercoat layer is applied onto the conductive layer by dip coating, and the obtained coating film is heated at 160° C. for 40 minutes to evaporate the solvent and cure the solution, so that the undercoat film has a thickness of 1.4 μm. Layers were formed.
The volume resistivity of the undercoat layer was measured by the method described above in the state where the conductive support, the conductive layer and the undercoat layer were laminated in this order. The measurement results are shown in Table 23.

<Production Example of Image Carrier (D-4)>
The image carrier (D-1) was prepared in the same manner as the image carrier (D-1) except that the preparation of the undercoat layer was changed as follows.
3.0 parts of the electron-transporting compound represented by the above formula (11),
N-methoxymethylated nylon as a binder resin (trade name: Toresin EF-30T, Nagase Chemtex Co., Ltd. (formerly Teikoku Chemical Industry Co., Ltd.)) 4.5 parts Methanol (Kishida Chemical Co., Ltd. ), special grade) 25.0 parts and n-butanol (Kishida Chemical Co., Ltd. special grade) 6.5 parts were mixed and stirred to dissolve. Furthermore, 5.0 parts of titanium oxide (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) and 25 parts of glass beads having a diameter of 0.8 mm were added to obtain a mixed solution. This mixed solution was subjected to a dispersion treatment for 16 hours with a paint shaker, and glass beads were removed to obtain an undercoat layer coating solution.

This coating liquid for undercoat layer was applied onto the conductive layer by dip coating, and the obtained coating film was heated at 100° C. for 40 minutes to evaporate the solvent and form an undercoat layer having a film thickness of 1.3 μm.
The volume resistivity of the undercoat layer was measured by the method described above in the state where the conductive support, the conductive layer and the undercoat layer were laminated in this order. The measurement results are shown in Table 23.

<Production Example of Binder Resin (F-1) for Toner>
Bisfer A ethylene oxide adduct (2.0 mol addition) 50.0 mol parts Bisfer A propylene oxide adduct (2.3 mol addition) 50.0 mol parts Terephthalic acid 60.0 mol parts Trimellitic anhydride 20. 0 mol parts/acrylic acid 10.0 mol parts 70 parts by mass of the mixture of the above polyester monomers was charged into a 4-neck flask, and equipped with a decompressor, a water separator, a nitrogen gas introducing device, a temperature measuring device and a stirrer under a nitrogen atmosphere. And stir at 160°C. A mixture of 30 parts by mass of a vinyl-based polymerization monomer (styrene: 90.0 mol parts, butyl acrylate: 10.0 mol parts) constituting the vinyl polymer part and 2.0 mol parts of benzoyl peroxide as a polymerization initiator was added thereto. It dripped from the dropping funnel over 4 hours. Then, after reacting at 160° C. for 5 hours, the temperature was raised to 230° C., 0.05 mass% of tetraisobutyl titanate was added, and the reaction time was adjusted so as to obtain a desired viscosity.
After completion of the reaction, the product was taken out from the container, cooled and pulverized to obtain a toner resin (F-1) which was a hybrid resin. Table 19 shows various physical properties of the obtained resin (F-1).

<Production Example of Toner Binder Resin (F-2)>
A toner binder resin (F-2) was obtained in the same manner as in the production example of the toner binder resin (F-1) except that the monomers shown in Table 19 were used. Table 19 shows various physical properties of the obtained binder resin for toner (F-2).

<Production Examples of Toner Binder Resins (F-3) and (F-4)>
The monomers shown in Table 19 were charged in a 5 liter autoclave together with 0.05% by mass of tetraisobutyl titanate based on the total amount of monomers, and equipped with a reflux condenser, a water separator, a nitrogen gas introduction pipe, a thermometer and a stirrer. .. Then, a polycondensation reaction was carried out at 230° C. while introducing nitrogen gas into the autoclave. The reaction time was adjusted to reach the desired softening point. After completion of the reaction, the product was taken out of the container, cooled and pulverized to obtain toner resins (F-3) and (F-4). Table 19 shows the physical properties of the obtained toner resins (F-3) and (F-4).

<Production Example of Toner Binder Resin (F-5)>
Into a four-necked flask, 250 parts by mass of degassed water and 50 parts by mass of a 1% by mass aqueous solution of polyvinyl alcohol were charged, and then 83 parts by mass of styrene, 17 parts by mass of n-butyl acrylate, and 0.001 part by mass of divinylbenzene. And a mixed solution of 0.1 parts by mass of 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane were added and stirred to obtain a suspension.

The inside of the four-necked flask was put under a nitrogen atmosphere and then heated to 85° C. to start polymerization. After maintaining at the same temperature for 20 hours, 0.1 part by mass of benzoyl peroxide was additionally added, and further maintaining for 8 hours to complete the polymerization. Next, the polymer particles were filtered off, washed thoroughly with water, and dried to obtain a binder resin (F-5) for toner.
The binder resin (F-5) for toner had a Tg of 61.2°C and a softening point of 143.5°C.

<Production Example of Toner Binder Resin (F-6)>
300 parts by mass of xylene was put into a four-necked flask, the inside of the container was sufficiently replaced with nitrogen while stirring, and then the temperature was raised to reflux.
Under this reflux, a mixed solution of 83 parts by mass of styrene, 17 parts by mass of -n-butyl acrylate, and 2 parts by mass of di-tert-butyl peroxide was added dropwise over 4 hours, and then the mixture was held for 2 hours for polymerization. Upon completion, a low molecular weight polymer solution was obtained. This polymer solution was dried under reduced pressure to obtain a binder resin for toner (F-6).
The binder resin (F-6) for toner had a Tg of 60.0°C and a softening point of 97.3°C.

<Production Example of Toner Magnetic Particles (G-1)>
(1) Manufacture of Core Particles 92 L of an aqueous ferrous sulfate solution having a Fe ²⁺ concentration of 1.79 mo1/L and 88 L of a 3.74 N aqueous sodium hydroxide solution were added and mixed and stirred. The pH of this solution was 6.5.
While maintaining this solution at a temperature of 89° C. and a pH of 9 to 12, 20 L/min of air was blown in to cause an oxidation reaction to generate core particles. When the ferrous hydroxide was completely consumed, the blowing of air was stopped and the oxidation reaction was terminated. The obtained magnetite core particles had an octahedral shape.

(2) Formation of coating layer 5 L of an aqueous solution prepared by mixing 2 L of a 0.7 mol/L aqueous solution of sodium silicate and 2 L of a 0.9 mol/L aqueous solution of ferrous sulfate was used as a slurry after the reaction containing 13500 g of core particles. Added while maintaining pH 8-9. Then, 10 L/min of air was blown in until the Fe2+ in the slurry did not remain.

Subsequently, 5 L of an aqueous solution obtained by mixing 2 L of the 1.5 mol/L aqueous solution of aluminum sulfate and 2 L of the 0.9 mol/L aqueous solution of ferrous sulfate was added to the post-reaction slurry containing the core particles while maintaining pH 8-9. did. Then, 10 L/min of air was blown in until the Fe2+ in the slurry did not remain. The temperature of the slurry was maintained at 89°C. After mixing and stirring for 30 minutes, the slurry was filtered, washed and dried to obtain the target magnetic particles for toner (G-1). With respect to the magnetic particles for toner (G-1), as a result of observing the method for measuring the presence/absence of a protrusion of the magnetic particle by the above method, a protrusion 1401 was observed on the surface as shown in FIG. In addition, Table 20 shows the physical properties of the magnetic particles for a toner (G-1).

<Production Example of Magnetic Particles (G-2) (G-3) for Toner>
In the production example of the magnetic particles for a toner (G-1), except that the production conditions were changed as shown in Table 20, the magnetic particles for a toner were prepared in the same manner as in the production method of the production example of the magnetic particles for a toner (G-1). (G-2) and (G-3) were obtained. Table 20 shows properties of the magnetic particles (G-2) and (G-3) for toner.

<Production Example of Toner (H-1)>


-Binder resin for toner (F-1) 55 parts by mass-Binder resin for toner (F-4) 45 parts by mass-Magnetic particles (G-1) 60 parts by mass-Release agent Fischer-Tropsch wax (Sazol Co.) C105, melting point 105° C.) 2 parts by mass charge control agent (T-77: Hodogaya Chemical Co., Ltd.) 2 parts by mass The above materials were premixed with an FM mixer (manufactured by Nippon Coke Industry Co., Ltd.). Then, it was melt-kneaded by a twin-screw kneading extruder (PCM-30 type manufactured by Ikegai Co., Ltd.).

The obtained kneaded product was cooled, roughly crushed with a hammer mill, and then crushed with a mechanical crusher (T-250 manufactured by Freund Turbo Co., Ltd.). The resulting finely pulverized powder was classified using a multi-division classifier utilizing the Coanda effect to obtain negatively chargeable toner particles having a weight average particle size (D4) of 7.0 μm.
Next, with respect to 100 parts by mass of the toner particles, 1.0 part by mass of hydrophobic silica fine powder [BET specific surface area of 200 m ² /g, and silica fine powder being hydrophobized with dimethyl silicone oil] was added to strontium titanate. 0.2 parts by mass of fine powder was externally mixed and sieved with a mesh having a mesh size of 100 μm to obtain a toner (H-1). Table 21 shows properties of the toner (H-1).

<Production Example of Toners (H-2) to (H-17)>
Toners (H-2) to (H-17) were obtained in the same manner as in the production example of toner (H-1) except that the formulations shown in Table 21 were used. Table 21 shows the physical properties of the obtained toners (H-2) to (H-17).

<Example 1>
As a machine used for evaluation in this example, a commercially available magnetic one-component printer HP LaserJet Enterprise 600 M603dn (manufactured by Hewlett Packard: process speed 350 mm/sec) and a cartridge CE390X were modified as follows.
・Change the process speed to 400 mm/sec. ・Change the charging member to the charging member (C-1) ・Change the image bearing member to (D-2) In this evaluation machine, under each of the following environments, the printing rate is 2%. An endurance test of 50,000 sheets (the rotation of the printer was stopped for 3 seconds each time one sheet was printed) was performed intermittently with one horizontal line image.
Under low temperature and low humidity environment (temperature 15℃, relative humidity 10%),
Under normal temperature and humidity environment (temperature 23°C, relative humidity 60%),
Under high temperature and high humidity environment (temperature 32.5°C, relative humidity 80%).

[Vertical stripe image]
In a low temperature and low humidity environment, a halftone image was output at the end of 50,000 sheets, and the generation state of vertical stripe images due to uneven wear of the image bearing member was evaluated from the image.
The evaluation criteria are as follows.
A: Not generated B: Only slight generation C: Occurrence was observed in a part of the image, but there was no problem in practical use D: Image quality deteriorated due to generation Table 22 shows the results.

[Halftone density unevenness]
Under all evaluation environments, a halftone image was output at the end of 50,000 sheets, and the generation state of halftone density unevenness was evaluated from the image. The evaluation criteria are as follows.
A: Almost no halftone density unevenness is visible.
B: Halftone density unevenness is slightly visible but difficult to understand.
C: Level at which halftone density unevenness is visible but not noticeable.
D: Halftone density unevenness is clearly visible.
The results are shown in Table 22.

[Evaluation of spot-shaped image]
Under a low temperature and low humidity environment, a halftone image was output at the end of 50,000 sheets and the generation state of a spot-like image was evaluated. The evaluation criteria are as follows: A: No spot-like image defects are recognized.
B: Only spot-like image defects are recognized.
C: It is recognized that spot-like image defects are generated in a part of the area in correspondence with the rotation pitch of the charging roller, but there is no practical problem.
D: Spot-like image defects are recognized in a wide range and are conspicuous.
The results are shown in Table 22.

[Evaluation of horizontal stripe image]
Under a low temperature and low humidity environment, a halftone image was output at the end of 50,000 sheets, and the state of occurrence of lateral stripe images due to charging was evaluated. The evaluation criteria are as follows: A: No horizontal stripe-shaped image defects are recognized.
B: Only horizontal stripe-shaped image defects are recognized.
C: It is recognized that horizontal stripe-shaped image defects are generated in a part of the area in correspondence with the rotation pitch of the charging roller, but there is no practical problem.
D: Horizontal stripe-shaped image defects are observed in a wide range and are conspicuous.
The results are shown in Table 22.

<Examples 2 to 12>
With the combinations shown in Table 22, the same evaluations as in Example 1 were performed. The results are shown in Table 22.
Examples 9 to 12 are described as reference examples.
<Comparative Examples 1 to 5>
With the combinations shown in Table 22, the same evaluations as in Example 1 were performed. The results are shown in Table 22.

As shown in Table 18, the charging members C-1 to C-7 satisfy the following mathematical formulas (1) to (3).
Formula (1) K2<K1
Formula (2) K3<K1
Formula (3) 0.8≦K2/K3≦1.2

As shown in Table 21,
Toners H-1 to H-14 are
The saturation magnetization is 15.0Am ² /kg or more and 35.0Am ² /kg or less in a magnetic field of 795.8kA/m, and the dielectric constant ε'is 25.0pF/m or more 40 at a frequency of 10kHz and a temperature of 40°C. It is not more than 0.0 pF/m.
The toners H-1 to H-10 and H-13 to H-14 contain 30 parts by mass or more and 70 parts by mass or less of magnetic particles with respect to 100 parts by mass of the binder resin.

As shown in Table 23, in the image carriers D-1 to D-3, the volume resistivity of the undercoat layer is 1×10 ¹¹ Ω·cm or more and 1×10 ¹⁶ Ω·cm or less.

1 conductive base, 2 conductive resin layer 11 bowl-shaped resin particles, 12 conductive resin layer (binder),
13 lining layer, 14 conductive resin layer (surface layer),
15 image carrier, 16 conductive fine particles, 17 concave portion, 18 convex portion,
21 conductive resin layer (intermediate layer), 22 conductive resin layer (surface layer)
31 cylindrical metal, 32 bearing, 33 conductive base, 34 charging member,
35 stabilized power supply, 36 ammeter 41 bowl-shaped resin particles, 42 conductive resin layer (binder)
51 bowl-shaped resin particle opening, 52 recessed portion derived from bowl-shaped resin particle opening 53 edge of bowl-shaped resin particle opening, 54 height difference,
55 maximum diameter of bowl-shaped resin particles 61 opening, 62 concave portion of opening, 63 minimum diameter of opening 81 bowl-shaped resin particles, 82 conductive resin layer (binder)
91 electron beam, 92 conductive substrate, 93 DC power supply 101 developing means, 102 toner, 103 image carrier (photoreceptor), 104 transfer means 105 exposure, 106 developing sleeve, 107 cleaning means,
108 toner coating blade, 109 magnetic field generating means 200 charging means, 201 to 203 bias applying means, 204 heating and pressing means P transfer material

Claims (5)

A charging step of charging the image bearing member by using a charging member in contact with the image bearing member,
An electrostatic latent image forming step of forming an electrostatic latent image on the image carrier,
A developing step of developing the electrostatic latent image with toner to form a toner image;
A transfer step of transferring the toner image to a recording medium with or without an intermediate transfer member, and a step of heating and fixing the toner image transferred to the recording medium,
An image forming method having:
The charging member has a conductive base and a conductive resin layer as a surface layer on the base,
Conductive resin layer comprises a binder, and the resin particles bowl shape having an opening, the opening is held in a state exposed on the surface of the charging member,
The surface of the charging member has a concave portion derived from the opening of the bowl-shaped resin particles exposed on the surface, and a convex portion derived from the edge portion of the opening of the bowl-shaped resin particle exposed on the surface. Have
The toner contains a binder resin and magnetic particles,
The magnetic particles are magnetic particles having a core of magnetite particles and having a coating layer as an outermost layer on the surface of the magnetite particles,
The coating layer contains an oxide containing iron, and at least one oxide selected from the group consisting of oxides containing silicon and oxides containing aluminum,
The magnetite particles are magnetite particles having a shape of an octahedron and having a convex portion on a plane portion forming the octahedron,
The saturation magnetization of the toner is 15.0 Am ² /kg or more and 35.0 Am ² /kg or less at a magnetic field of 795.8 kA/m, and the dielectric constant ε'of the toner is 25.0 pF at a frequency of 10 kHz and a temperature of 40° C. /M or more and 40.0 pF/m or less ,
An image forming method characterized by the above. The toner, the magnetic particles, the image forming method according to claim 1, wherein 100 parts by weight of the binder resin having 70 parts hereinafter containing more than 30 parts by weight. Part of the surface of the charging member is constituted by said conductive resins layer,
Wherein the charging member while applying a following direct current voltage higher than 50V 100V between the oppositely arranged so the electrode and the base body, the surface of the charging member, using a scanning electron microscope, acceleration voltage 1 kV, magnification 2000 Observe at double,
The luminance of convex portions derived from the edge portion of the opening of the resin particles of the bowl-shaped and K1, the luminance at the bottom of the recess from the opening of the resin particles of the bowl-shaped and K2, the exposed surface of the conductive resin layer When the brightness at is K3,
The K1, the K2, and the K3 satisfies the following formula (1) to (3),
Formula (1) K2<K1
Formula (2) K3<K1
Formula (3) 0.8≦K2/K3≦1.2
The image forming method according to claim 1. The image carrier has a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer,
The volume resistivity of the undercoat layer is not more than 1 × ^{10 11} Ω · cm or more 1 × ^{10 16} Ω · cm,
The undercoat layer contains an electron transporting compound,
The image forming method according to claim 1. The image forming method according to claim 1, wherein the coating layer contains an oxide containing the iron, an oxide containing the silicon, and an oxide containing the aluminum.