JP2018128515A - Electrophotographic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus that can reduce the occurrence of white streaks at a lead part and carrier adhesion.SOLUTION: In an electrophotographic image forming apparatus of the present invention, (1) a surface protective layer contains N-type semiconductor particles, and the N-type semiconductor particles have a volume resistivity within a range of 1.0×10to 1.0×10Ω cm, and an average particle diameter within a range of 50 to 300 nm; (2) a toner includes a toner base particle having a domain-matrix structure, where the domain contains a crystalline polyester resin and the matrix contains an amorphous resin; (3) a carrier has a resistance within a range of 1.0×10to 1.0×10Ω cm.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrophotographic image forming apparatus. More specifically, the present invention relates to an electrophotographic image forming apparatus capable of suppressing the occurrence of lead white spots and carrier adhesion.

  In electrophotographic image formation, an electrostatic latent image formed on an electrostatic latent image carrier (hereinafter also referred to as “photosensitive member” or “photosensitive drum”) is developed and visualized with toner. As this developing method, there are conventionally known two methods, a forward developing method and a reverse developing method, depending on the rotating direction of the developing sleeve of the developing device that rotates while holding the developer and the photosensitive member.

FIG. 1A is a schematic diagram for explaining a normal development method, and FIG. 1B is a schematic diagram for explaining a reverse development method.
The forward rotation developing method shown in FIG. 1A is a developing method in which the rotation direction W1 of the photosensitive member P is clockwise, the rotation direction W2 of the developing sleeve S is counterclockwise, and the rotation directions W1 and W2 are opposite directions. It is. In this forward rotation development method, development is performed by bringing the surface of the photoreceptor P and the surface of the development sleeve into contact in the same direction in the development region where the surface of the photoreceptor P and the developer on the development sleeve S are in contact with each other. .

  In the reverse developing method shown in FIG. 1B, the rotation direction W1 ′ of the photosensitive member P ′ is counterclockwise, the rotation direction W2 ′ of the developing sleeve S ′ is counterclockwise, and the rotation directions W1 ′ and W2 ′ are the same. It is a developing method that is a direction. In this reverse development method, the surface of the photosensitive member and the developer on the developing sleeve S are in contact with each other in the reverse direction in the developing region.

In both the forward development system and the reverse development system, the scavenging phenomenon, that is, the carrier electrostatically scrapes off the toner developed on the photoconductor, and disturbs the image such as the halftone image being whitened out. A phenomenon (image defect) occurs.
In the forward developing method, image defects due to the scavenging phenomenon occur particularly noticeably.

  A specific example of the image defect due to the scavenging phenomenon will be described with reference to FIG. FIG. 2 is a schematic diagram showing an image defect that occurs when a document on which a solid image G1 exists adjacent to the rear end of the halftone image G2 with respect to the paper feeding direction A is printed. When such a print is performed, as shown in the figure, the halftone image at the rear end of the halftone image, that is, the halftone image near the boundary with the solid image, tends to be white (hereinafter also referred to as “lead portion whiteout”). Such a problem arises and improvement is demanded.

The cause of the scavenging phenomenon is a difference in rotational speed between the developing sleeve S and the photosensitive member P, and occurs when the rotational speed of the developing sleeve S is set higher than the rotational speed of the photosensitive member P. More specifically, when a solid image is developed, a large amount of toner is supplied to the photoconductor, so that charges remain on the carrier on the developing sleeve, and the carrier overtakes the solid image portion on the photoconductor, When the halftone image portion is reached, the toner that forms the halftone image is electrostatically scraped off, so that a scavenging phenomenon occurs.
As a method for suppressing the occurrence of the scavenging phenomenon, it has been proposed to lower the carrier resistance (hereinafter also referred to as “carrier resistance”). By reducing the carrier resistance, the carrier charge generated during solid image development is easily lost, and as a result, the toner is not scraped off, and the occurrence of the scavenging phenomenon can be suppressed. Can be suppressed.

As a method for adjusting the carrier resistance, for example, Patent Document 1 discloses adjusting the resistance of the carrier core particle itself and the thickness of the resin coating layer.
On the other hand, it is not necessary to lower the carrier resistance. When the carrier resistance is too low, a phenomenon (so-called “carrier adhesion”) in which carriers adhere to the photoreceptor due to charge injection occurs during development. . Here, the carrier adhesion specifically means that when the carrier resistance is low, charge is injected from the developing sleeve S to the carrier by the voltage applied to the developing sleeve S. As a result, the carrier adheres to the photoreceptor P. It is a phenomenon that does. When such carrier adhesion occurs, a defect occurs in the output image. For this reason, it is necessary to adjust the carrier resistance to an appropriate range so that the occurrence of white spots in the lead due to the scavenging phenomenon can be suppressed and the carrier adhesion to the photoconductor can be suppressed. It is difficult to achieve both.

JP 2002-139900 A

  The present invention has been made in view of the above-described problems and situations, and a problem to be solved is to provide an electrophotographic image forming apparatus capable of suppressing the occurrence of white spots in the lead portion and carrier adhesion.

In order to solve the above-mentioned problems, the present inventor defines the configuration relating to the electrical resistivity of the photoconductor, toner, and carrier in the process of examining the cause of the above-mentioned problem, thereby leading to the lead caused by the scavenging phenomenon. The present inventors have found that carrier adhesion can also be suppressed while suppressing the occurrence of white spots.
That is, the said subject which concerns on this invention is solved by the following means.

1. An electrostatic latent image carrier having at least a photosensitive layer and a surface protective layer on a conductive support; a developing means using a charging means, an exposure means, a developer containing toner and a carrier; a transfer means; a fixing means; a cleaning means; An electrophotographic image forming apparatus comprising:
(1) The surface protective layer contains N-type semiconductor particles,
The N-type semiconductor particles have a volume resistivity in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω · cm, and an average particle size in the range of 50 to 300 nm,
(2) the toner contains toner base particles having a domain matrix structure;
The domain contains a crystalline polyester resin and the matrix contains an amorphous resin;
(3) The electrophotographic image forming apparatus, wherein the resistance of the carrier is in a range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm.

2. 2. The electrophotographic image forming apparatus according to item 1, wherein the resistance of the carrier is in the range of 1.0 × 10 ^{9 to} 5.0 × 10 ¹⁰ Ω · cm.

  3. The electrophotographic image forming apparatus according to claim 1 or 2, wherein the N-type semiconductor particles contain any one of tin oxide, titanium oxide, zinc oxide, and indium tin oxide.

  4). The electrophotographic image forming apparatus according to any one of Items 1 to 3, wherein the amorphous resin contained in the matrix contains styrene / acrylic resin.

5). The crystalline polyester resin contained in the domain is
When the carbon number of the main chain of the structural unit derived from the polyhydric alcohol is _Calcohol and the carbon number of the main chain of the structural unit derived from the polyvalent carboxylic acid is C _acid , the following relational expressions (1) and (2 The electrophotographic image forming apparatus according to any one of items 1 to 4, wherein:
5 ≦ | C _acid −C _alcohol ≦≦ 12 (1)
_Calcohol <C _acid ... relational expression (2)

  6). The crystalline polyester resin contained in the domain is a hybrid crystalline polyester resin in which a styrene / acrylic polymer segment is chemically bonded to a polyester polymer segment, The electrophotographic image forming apparatus according to any one of the above.

  7). The electrophotographic image forming apparatus according to any one of Items 1 to 6, wherein the developing unit is a unit that performs development by a normal rotation developing method.

By the above means of the present invention, it is possible to provide an electrophotographic image forming apparatus capable of suppressing the occurrence of lead white spots and carrier adhesion.
Although the expression mechanism or action mechanism of the effect of the present invention is not clear, the following knowledge has been obtained.

The following two methods are conceivable to suppress the occurrence of the scavenging phenomenon that causes the lead portion to be white.
(I) Eliminate carrier positive charge (ii) Eliminate toner negative charge

  Generally, it is possible to suppress the occurrence of the scavenging phenomenon by lowering the carrier resistance. However, if the carrier resistance is lowered too much, carrier adhesion due to charge injection during development is likely to occur. Defects may occur.

The present inventor has added negative toner charge to the photoreceptor by adding N-type semiconductor particles having a volume resistivity in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω · cm. It was found that it can be easily released to the photoreceptor side.
Further, the present inventor believes that the transfer of charge is more likely to occur because the toner volume particle resistivity can be appropriately lowered by incorporating a crystalline polyester resin domain having a low electrical resistivity into the toner base particles. It was. By doing so, it is possible to suppress the occurrence of the scavenging phenomenon without excessively reducing the carrier resistance (for example, less than 1.0 × 10 ⁹ Ω · cm), and in turn, it is possible to suppress the occurrence of whiteout in the lead portion. Therefore, it has been found that it is possible to achieve both the suppression of the occurrence of carrier adhesion.

The present inventor has also found the following.
When the volume resistivity of the N-type semiconductor particles is less than 1.0 × 10 ⁴ Ω · cm, it becomes difficult to form a latent image and it is difficult to obtain a clean image, and when the volume resistivity is greater than 1.0 × 10 ⁷ Ω · cm. The effect of suppressing the occurrence of the scavenging phenomenon is small.
Furthermore, when the average particle size of the N-type semiconductor particles is less than 50 nm, the particles are too small and the conduction path does not work well. As a result, the negative charge is not released well to the photoconductor, resulting in scavenging phenomenon. The occurrence cannot be suppressed.
Further, when the average particle diameter of the N-type semiconductor particles is larger than 300 nm, conduction paths can be made, but the number of the conduction paths is small, and as a result, negative charges are not released well to the photoconductor, resulting in a scavenging phenomenon. The occurrence cannot be suppressed.

On the other hand, when the carrier resistance is less than 1.0 × 10 ⁹ Ω · cm, carrier adhesion due to charge injection during development deteriorates, resulting in image defects. When the carrier resistance is larger than 1.0 × 10 ¹¹ Ω · cm, the effect of suppressing the scavenging phenomenon is low.

Schematic diagram explaining the forward development method Schematic explaining the reverse development method Schematic explaining the scavenging phenomenon Schematic sectional view showing an example of an electrophotographic image forming apparatus according to the present invention FIG. 3 is a schematic cross-sectional view showing an example of a developing device according to the electrophotographic image forming apparatus of FIG. Schematic cross-sectional view of an N-type semiconductor particle manufacturing apparatus used in the examples

In the electrophotographic image forming apparatus of the present invention, (1) the surface protective layer of the electrostatic latent image carrier contains N-type semiconductor particles, and the N-type semiconductor particles have a volume resistivity of 1.0 × 10 ^4. -1.0 × 10 ⁷ Ω · cm and an average particle diameter in the range of 50-300 nm, (2) the toner contains toner base particles having a domain matrix structure, and a domain Contains a crystalline polyester resin, and the matrix contains an amorphous resin, and (3) the resistance of the carrier is in the range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm. It is characterized by.
This feature is a technical feature common to or corresponding to the claimed invention. Thereby, this invention can suppress generation | occurrence | production of a lead part white spot and carrier adhesion.

In an embodiment of the present invention, the resistance of the carrier is preferably in the range of 1.0 × 10 ^{9 to} 5.0 × 10 ¹⁰ Ω · cm. Thereby, generation | occurrence | production of a lead part white-out and carrier adhesion can be suppressed more.

  As an embodiment of the present invention, the N-type semiconductor particles preferably contain any one of tin oxide, titanium oxide, zinc oxide and indium tin oxide. Thereby, the effect of this invention can be show | played more suitably.

  As an embodiment of the present invention, it is preferable that a styrene-acrylic resin is contained as the amorphous resin contained in the matrix. Thereby, generation | occurrence | production of a lead part white spot can be suppressed more.

As an embodiment of the present invention, the crystalline polyester resin contained in the domain has a main unit of a structural unit derived from a polyvalent carboxylic acid in which the number of carbons of the main chain of the structural unit derived from the polyhydric _alcohol is _Calcohol. When the carbon number of the chain is C _acid , it is preferable to satisfy the relational expressions (1) and (2). Thereby, generation | occurrence | production of a lead part white spot can be suppressed more.

  As an embodiment of the present invention, the crystalline polyester resin contained in the domain is preferably a hybrid crystalline polyester resin in which a styrene / acrylic polymer segment is chemically bonded to a polyester polymer segment. Thereby, generation | occurrence | production of a lead part white spot can be suppressed more.

  As an embodiment of the present invention, the developing means may be a means for developing by a forward developing method. According to the present invention, it is possible to effectively suppress the occurrence of white spots in the lead portion and carrier adhesion even with a means for developing by the forward developing method.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

≪Outline of electrophotographic image forming apparatus≫
The electrophotographic image forming apparatus of the present invention is a developing unit using an electrostatic latent image carrier having at least a photosensitive layer and a surface protective layer on a conductive support, and a developer including a charging unit, an exposing unit, a toner and a carrier. An electrophotographic image forming apparatus comprising a transfer unit, a fixing unit, and a cleaning unit,
(1) The surface protective layer contains N-type semiconductor particles,
The N-type semiconductor particles have a volume resistivity in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω · cm, and an average particle size in the range of 50 to 300 nm,
(2) the toner contains toner base particles having a domain matrix structure;
The domain contains a crystalline polyester resin and the matrix contains an amorphous resin;
(3) The carrier has a resistance in a range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm.

[Electrostatic latent image carrier]
The electrostatic latent image carrier (hereinafter also referred to as “photoreceptor”) according to the present invention has at least a photosensitive layer and a surface protective layer on a conductive support. The body is not particularly limited as long as a photosensitive layer and a surface protective layer are laminated in this order on a conductive support, and specific examples thereof include the following (1) and (2) layer configurations. .
(1) Layer structure in which an intermediate layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a surface protective layer are laminated in this order on a conductive support (2) an intermediate layer on a conductive support, Layer structure in which a single layer containing a charge generating material and a charge transport material as a photosensitive layer and a surface protective layer are laminated in this order

  The electrostatic latent image carrier according to the present invention is an organic photoconductor, and the organic photoconductor is an organic compound having at least one of a charge generation function and a charge transport function essential to the configuration of the electrostatic latent image carrier. Means an electrostatic latent image bearing member (so-called electrophotographic photosensitive member) expressed by the above, and an electrostatic latent image bearing member composed of a known organic charge generating material or organic charge transporting material, charge generating function and charge An electrostatic latent image carrier having a transport function and a polymer complex is included.

<Surface protective layer>
The surface protective layer of the electrostatic latent image carrier according to the present invention contains N-type semiconductor particles. Specifically, the surface protective layer is preferably formed on the photosensitive layer, and preferably includes the N-type semiconductor particles according to the present invention in a binder resin. Further, a charge transporting compound may be contained.
The binder resin is not particularly limited, and those used for ordinary organic photoreceptors can be suitably used. Among them, a cured resin is preferable from the viewpoint of durability.

(N-type semiconductor particles)
The N-type semiconductor particles according to the present invention are semiconductor particles in which electrons are used as carriers for transporting charges. That is, a semiconductor in which electrons are majority carriers. One type or more of N-type semiconductor particles may be used.
As the N-type semiconductor particles, tin oxide, titanium oxide, zinc oxide and indium tin oxide, which are conductive metal oxides, are preferable from the viewpoint of electrical resistance. The N-type semiconductor particle according to the present invention may be a known particle containing an N-type semiconductor. For example, the N-type semiconductor particle may be attached to the surface of an insulating particle. When particles are formed with an N-type semiconductor alone, it may be difficult to increase the particle size, but using such insulating particles as a core makes it easier to produce N-type semiconductor particles with a large particle size. . Insulating particles are preferably barium sulfate, alumina, silica, and the like, among which barium sulfate is preferable. The amount of the conductive metal oxide attached to the core material is preferably 30 to 70% by mass, and more preferably 40 to 60% by mass. When the adhesion amount is within the above range, high potential characteristics can be ensured.

  As a method for adhering the conductive metal oxide to the core material, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2009-255042 can be employed.

  Moreover, it is preferable that the surface of the N-type semiconductor particle according to the present invention is modified with a surface modifier (so-called surface treatment agent) containing a compound having a radical polymerizable functional group. Specifically, the conductive metal oxide, which is an N-type semiconductor particle, is subjected to radical polymerization on the surface of the N-type semiconductor particle by treating the surface with a surface modifier containing a compound having a radical polymerizable functional group. It is preferable that the functional group is modified.

Since the surface of the N-type semiconductor particle is treated with a surface modifier composed of a compound having a radical polymerizable functional group, polyfunctional radical polymerization is performed in step (4) in the method for producing a photoreceptor to be described later. It is possible to form a cross-linked structure by reacting with a functional compound, sufficient film strength of the surface protective layer can be obtained, potential stability can be obtained, and both high durability and potential characteristics can be achieved. Moreover, high dispersibility is obtained for the metal oxide fine particles in the cured resin.
In addition, as a radically polymerizable functional group in a surface modifier, the compound described in Paragraph 0044 to 0048 of Unexamined-Japanese-Patent No. 2015-022297 is mentioned, for example.
The surface modification method is not particularly limited, and for example, the method described in paragraphs 0050 to 0053 of JP-A-2015-022297 can be employed.
In addition, it is preferable that the processing amount of a surface modifier is 0.1-200 mass parts with respect to 100 mass parts of N-type semiconductor particles, More preferably, it is 7-70 mass parts.

The N-type semiconductor particles are preferably contained in a proportion of 50 to 250 parts by mass with respect to 100 parts by mass of the resin of the surface protective layer, more preferably 70 to 200 parts by mass, and particularly preferably 80 to 150 parts by mass. Part.
When the content ratio of the N-type semiconductor particles is 50 parts by mass or more, the conduction path can be suitably connected, and as a result, no negative charge is emitted to the electrostatic latent image carrier. Moreover, if it is 250 mass parts or less, an electrostatic latent image can be formed appropriately and, as a result, a more beautiful image can be obtained.

The N-type semiconductor particles according to the present invention have a volume resistivity in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω · cm, and an average particle size in the range of 50 to 300 nm.
The N-type semiconductor particles preferably contain any one of tin oxide, titanium oxide, zinc oxide, and indium tin oxide. Thereby, it is easy to adjust volume resistivity suitably, and the effect of this invention can be show | played more suitably.
When it is less than 1.0 × 10 ⁴ Ω · cm, it is difficult to form a latent image and it is difficult to obtain a clean image. When it exceeds 1.0 × 10 ⁷ Ω · cm, the effect of suppressing the occurrence of the scavenging phenomenon is reduced.
On the other hand, when the average particle size is less than 50 nm, the particles are too small and the conduction path does not work well. As a result, the negative charge is not released well to the photoconductor, and the occurrence of the scavenging phenomenon cannot be suppressed.
When the average particle diameter exceeds 300 nm, a conduction path can be made, but the starting point of the negative charge flowing decreases, and as a result, the negative charge is not released to the photoconductor well, and the occurrence of the scavenging phenomenon cannot be suppressed.
The particle size distribution of the N-type semiconductor particles according to the present invention preferably has a particle size at a position corresponding to the peak top of the maximum peak in the range of 50 to 300 nm from the viewpoint of manifesting the effects of the present invention. .
“The particle size at the position corresponding to the peak top of the maximum peak” means the particle size distribution (frequency distribution) of N-type semiconductor particles when “horizontal axis: particle size” and “vertical axis: abundance ratio” are used. The portion showing the maximum abundance ratio is defined as the peak top, which means the particle size at the position corresponding to the peak top.

(Measurement method of volume resistivity of N-type semiconductor particles)
The volume resistivity is obtained by passing a constant current I (A) through a cross-sectional area W × t and measuring a potential difference V (V) between electrodes separated by a distance L.
Definition of volume resistivity (Ω · cm) Cross-sectional area = W x t
Resistance R = V / I
Volume resistivity VR (Ω · cm) = (W × t / L) × (V / I)
The specific measurement method is as described in the examples. For example, the volume resistivity (Ω · cm) of the N-type semiconductor particles is set in a container having electrodes arranged in parallel at intervals of 2 mm. The particles can be filled and the direct current resistance can be measured by an insulation resistance meter (for example, 4329A High Resistance Meter manufactured by Japan Hewlett-Packard Co., Ltd.).

(Average particle size of N-type semiconductor particles)
The average particle size of the N-type semiconductor particles is calculated from a photograph image obtained by observing and photographing the N-type semiconductor particles with a transmission electron microscope. The magnification of the microscope is set to 10,000 times, and a photograph is taken. 100 particles are extracted at random from the image and calculated. Specifically, the horizontal ferret diameter of 100 fine particles is measured by image analysis processing, an average value is calculated, and this is set as the number average primary particle diameter. Note that the image analysis processing can be automatically performed by, for example, driving a program built in the transmission electron microscope measurement apparatus. In the present invention, for example, a transmission electron microscope “JEM-2000FX” (manufactured by JEOL Ltd.) can be used to measure the particle size of the fine particles.

(Cured resin)
The cured resin is a main component constituting the surface protective layer. This cured resin is obtained by polymerizing a compound having two or more radical polymerizable functional groups (hereinafter also referred to as “polyfunctional radical polymerizable compound”). Specifically, the curable resin is formed by polymerizing and curing a polyfunctional radical polymerizable compound by irradiation with active rays such as ultraviolet rays and electron beams.

As the monomer for forming the curable resin, a polyfunctional radical polymerizable compound is used, but a compound having one radical polymerizable functional group (hereinafter also referred to as “monofunctional radical polymerizable compound”) is used in combination. You can also. In the case of using a monofunctional radically polymerizable compound, the ratio is preferably 10 to 50% by mass with respect to the total amount of monomers for forming the cured resin.
Examples of the radical polymerizable functional group include a vinyl group, an acryloyl group, and a methacryloyl group.

Since the polyfunctional radical polymerizable compound can be cured in a small amount of light or in a short time, an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—) is used as the radical polymerizable functional group. (Meth) acrylic monomers having 2 or more) or oligomers thereof are particularly preferred.

  In the present invention, the polyfunctional radically polymerizable compound may be used alone or in combination. In addition, these polyfunctional radical polymerizable compounds may use monomers, but may be used after oligomerization.

  Hereinafter, specific examples of the polyfunctional radically polymerizable compound are shown.

However, in the chemical formulas showing the exemplary compounds (M1) to (M14), R represents an acryloyl group (CH ₂ ═CHCO—), and R ′ represents a methacryloyl group (CH ₂ ═CCH ₃ CO—).

(Charge transporting compound)
The charge transporting compound is not particularly limited as long as it has a charge transporting property of transporting charge carriers in the surface protective layer. For example, compounds described in paragraphs 0057 to 0059 of JP-A-2015-022297 It is. The compound can be synthesized by a known synthesis method, for example, a method disclosed in JP-A-2006-143720.
In addition, the charge transporting compound according to the present invention has no reactivity with N-type semiconductor particles surface-modified with a polyfunctional radically polymerizable compound or a surface modifier made of a compound having a radically polymerizable functional group. It is.

  The charge transporting compound is preferably contained in a proportion of 10 to 30 parts by mass, more preferably 15 to 25 parts by mass with respect to 100 parts by mass of the binder resin.

  The surface protective layer according to the present invention may contain other components in addition to the binder resin, the N-type semiconductor particles, and the charge transporting compound. For example, various antioxidants, for example, fluorine atom-containing resin particles Various lubricant particles such as can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and their co-polymers. It is preferable to appropriately select one or two or more types from the polymer, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  The layer thickness of the surface protective layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

<Conductive support>
The conductive support according to the present invention is only required to have conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum, copper, etc. Metal foil laminated with plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal, plastic film and paper with conductive layer applied alone or with binder resin Etc.

<Intermediate layer>
In the electrostatic latent image carrier of the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer. In consideration of various failure prevention, it is preferable to provide an intermediate layer.

  Such an intermediate layer includes, for example, a binder resin (hereinafter also referred to as “binder resin for intermediate layer”) and, if necessary, conductive particles (hereinafter also referred to as “conductive particles for intermediate layer”) or metal. Oxide particles (hereinafter also referred to as “intermediate layer metal oxide particles”) may be contained.

  Examples of the intermediate layer binder resin include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Among these, alcohol-soluble polyamide resins are preferable.

The intermediate layer can contain various conductive particles for intermediate layer and metal oxide particles for intermediate layer for the purpose of adjusting the resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.
The number-average primary particle diameter of such intermediate layer metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  These intermediate layer metal oxide particles may be used singly or in combination of two or more. When two or more kinds are mixed, they may take the form of a solid solution or fusion.

  The content ratio of the intermediate layer conductive particles or the intermediate layer metal oxide particles is preferably 20 to 400 parts by mass, more preferably 50 to 350 parts by mass with respect to 100 parts by mass of the intermediate layer binder resin. is there.

  The thickness of the intermediate layer is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

<Photosensitive layer>
The photosensitive layer according to the present invention may be a layer composed of two layers, a charge generation layer and a charge transport layer, or a single layer containing a charge generation material and a charge transport material.
In the following, a description will be given by taking as an example a layer composed of two layers, a charge generation layer and a charge transport layer.

(Charge generation layer)
The charge generation layer in the photosensitive layer according to the present invention contains a charge generation material and a binder resin (hereinafter also referred to as “binder resin for charge generation layer”).

  As the charge generation material, known materials can be used, and examples thereof include, but are not limited to, the charge generation materials described in JP-A-2015-22297. Among these, polycyclic quinone pigments and titanyl phthalocyanine pigments are preferable. These charge generation materials may be used alone or in combination of two or more.

  As the binder resin for the charge generation layer, a known resin can be used, and examples thereof include, but are not limited to, the binder resin for charge generation layer described in JP-A-2015-22297. is not. Among these, polyvinyl butyral resin is preferable.

  The content ratio of the charge generation material in the charge generation layer is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin for charge generation layer.

  The layer thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin for the charge generation layer, the content ratio, etc., but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. is there.

(Charge transport layer)
The charge transport layer in the photosensitive layer according to the present invention contains a charge transport material and a binder resin (hereinafter also referred to as “binder resin for charge transport layer”).

  Examples of the charge transport material for the charge transport layer include a charge transport material such as a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, and a butadiene compound.

  As the binder resin for the charge transport layer, a known resin can be used, and examples thereof include a binder tree for a charge transport layer described in JP-A-2015-22297, among which a polycarbonate resin is preferable. Furthermore, BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, BPA-dimethyl BPA copolymer type polycarbonate resin and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The content ratio of the charge transport material in the charge transport layer is preferably 10 to 500 parts by weight, more preferably 20 to 250 parts by weight with respect to 100 parts by weight of the charge transport layer binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics and the content ratio of the binder resin for the charge transport layer, but is preferably 5 to 40 μm, more preferably 10 to 30 μm.

  In the charge transport layer, an antioxidant, an electronic conductive agent, a stabilizer, silicone oil, or the like may be added. As the antioxidant, those disclosed in JP-A No. 2000-305291 and as the electronic conductive agent are disclosed in JP-A Nos. 50-137543 and 58-76483.

[Method for producing photoreceptor]
As a manufacturing method of the photoreceptor according to the present invention, for example, it can be manufactured through the following steps.
Process (1): The process of forming an intermediate | middle layer by apply | coating the coating liquid for intermediate | middle layer formation to the outer peripheral surface of an electroconductive support body, and drying.
Step (2): A step of forming a charge generation layer by applying a coating solution for forming a charge generation layer on the outer peripheral surface of an intermediate layer formed on a conductive support and drying it.
Step (3): A step of forming a charge transport layer by applying a coating liquid for forming a charge transport layer to the outer peripheral surface of the charge generation layer formed on the intermediate layer and drying.
Step (4): A coating solution is formed on the outer peripheral surface of the charge transport layer formed on the charge generation layer by coating a coating solution for forming a surface protective layer, and the coating film is cured to form a surface. Forming a protective layer;

  The steps (1) to (4) are as described in detail in paragraphs 0085 to 0119 of JP-A No. 2015-022297. Accordingly, the steps (1) to (4) will be briefly described below.

[Step (1): Formation of intermediate layer]
The intermediate layer is prepared by dissolving the binder resin for the intermediate layer in a solvent to prepare a coating liquid (hereinafter also referred to as “intermediate layer forming coating liquid”), and if necessary, conductive particles and metal oxide particles. After the dispersion, the coating solution can be formed on the conductive support in a certain film thickness to form a coating film, and the coating film can be dried.

  Examples of means for dispersing conductive particles and metal oxide particles in the intermediate layer forming coating solution, a method for applying the intermediate layer forming coating solution, a method for drying the coating film, and the type of the solvent are described in JP-A-2015-022297. The examples described in paragraphs 0086 to 0088 of the publication can be suitably employed.

[Step (2): Formation of Charge Generation Layer]
The charge generation layer is prepared by dispersing a charge generation material in a solution in which a charge generation layer binder resin is dissolved in a solvent to prepare a coating solution (hereinafter also referred to as “charge generation layer forming coating solution”). The coating solution can be formed on the intermediate layer by coating the intermediate layer with a certain film thickness to form a coating film and then drying the coating film.

  Means for dispersing the charge generation material, a coating method for forming a coating solution for forming a charge generation layer, a drying method for a coating film, a kind of solvent, and the like are described in, for example, paragraphs 0090 and 0091 of JP-A-2015-022297. Examples can be suitably employed.

[Step (3): Formation of Charge Transport Layer]
The charge transport layer is prepared by preparing a coating liquid in which a binder resin for a charge transport layer and a charge transport material are dissolved in a solvent (hereinafter also referred to as “charge transport layer forming coating liquid”), and generating a charge from the coating liquid. It can form by apply | coating to a fixed film thickness on a layer, forming a coating film, and drying the said coating film.

  As the coating method of the coating solution for forming the charge transport layer, the drying method of the coating film, the kind of the solvent, etc., for example, the examples described in paragraphs 0093 to 0094 of JP-A-2015-022297 can be suitably employed.

[Step (4): Formation of surface protective layer]
The surface protective layer is a coating liquid (hereinafter referred to as “surface protective layer”) by adding a polyfunctional radical polymerizable compound, N-type semiconductor particles, a charge transporting compound, a polymerization initiator and, if necessary, other components to a known solvent. The surface protective layer forming coating solution is applied to the outer peripheral surface of the charge transport layer formed in the step (3) to form a coating film. The surface protective layer can be formed by drying and irradiating active rays such as ultraviolet rays and electron beams to cure the radical polymerizable compound component in the coating film by polymerization reaction.

  In the process of coating, drying and curing, the surface protective layer has a surface modified by a reaction between polyfunctional radically polymerizable compounds or a surface modifier composed of a compound having N-type semiconductor particles having radically polymerizable functional groups. In the case of a product, it is formed as a cross-linked curable resin by the reaction of the surface modifier with the polyfunctional radical polymerizable compound.

  In the coating solution for forming the surface protective layer, the N-type semiconductor particles are based on 100 parts by mass of all monomers (polyfunctional radical polymerizable compound or monofunctional radical polymerizable compound) for forming a binder resin such as a cured resin. It is preferable to contain in the ratio of 50-250 mass parts, More preferably, it is 70-200 mass parts, Most preferably, it is 80-150 mass parts. Further, the charge transporting compound is in a ratio of 10 to 30 parts by mass with respect to 100 parts by mass of all monomers (polyfunctional radical polymerizable compound or monofunctional radical polymerizable compound) for forming a binder resin such as a cured resin. It is preferable to contain, More preferably, it is 15-25 mass parts.

  As a means for dispersing the N-type semiconductor particles in the coating solution for forming the surface protective layer, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but is not limited thereto.

  As the solvent used for forming the surface protective layer, any solvent can be used as long as it can dissolve or disperse the polyfunctional radical polymerizable compound, the N-type semiconductor particles, and the charge transporting compound. For example, methanol, ethanol, n -Propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, Examples include, but are not limited to, 1,3-dioxolane, pyridine, and diethylamine.

  As a coating method of the surface protective layer forming coating solution, for example, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method, etc. are known. The method is mentioned.

  The coating liquid for forming the surface protective layer is preferably applied using a circular slide hopper coating apparatus. The method for applying the coating solution for forming the surface protective layer using the circular slide hopper coating apparatus is not particularly limited, but for example, the method described in paragraphs 0102 to 106 of JP-A-2015-022297 can be employed. .

  The coating film may be cured without being dried, but it is preferable to perform the curing treatment after natural drying or heat drying.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

  Examples of the method of reacting the radical polymerizable compound include a method of reacting by electron beam cleavage and a method of reacting with light and heat by adding a radical polymerization initiator. As the radical polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. Moreover, a photoinitiator and a thermal polymerization initiator can also be used together.

  As the radical polymerization initiator, a photopolymerization initiator is preferable, and among them, an alkylphenone compound or a phosphine oxide compound is preferable. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable.

  Hereinafter, specific examples of acylphosphine oxide compounds as photopolymerization initiators are shown.

  The polymerization initiators may be used alone or in combination of two or more.

  It is preferable that the addition ratio of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of radically polymerizable compounds, More preferably, it is 0.5-10 mass parts.

  A cured resin is produced | generated by irradiating an active ray to a coating film as a hardening process, generating a radical, superposing | polymerizing, forming the cross-linking by a cross-linking reaction between molecules and in a molecule, and hardening. As the actinic radiation, ultraviolet rays and electron beams are more preferred, and ultraviolet rays are particularly preferred because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used.
Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² .
The power of the lamp is preferably from 0.1 to 5 kW, particularly preferably from 0.5 kW to 3 kW.

  Although it does not specifically limit as an electron beam source, For example, the electron beam source described in Paragraph 0117 of Unexamined-Japanese-Patent No. 2015-022297 can be used.

  The irradiation time for obtaining the necessary amount of active ray irradiation is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  In the step of forming the surface protective layer, drying can be performed before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.

[toner]
The toner according to the present invention contains toner base particles having a domain matrix structure.
In the present invention, “toner” refers to an aggregate of toner particles obtained by adding an external additive to toner base particles. The toner base particles can be handled as toner particles without adding any external additives.

<Toner base particles>
The toner base particles according to the present invention include an amorphous resin and a crystalline polyester resin. The toner base particles have a domain / matrix structure in which domains containing a crystalline polyester resin are dispersed in a matrix containing an amorphous resin. In the following description, the resins contained in the toner base particles such as crystalline polyester resin and amorphous resin are collectively referred to as “binder resin”.
As a constituent component of the toner base particles according to the present invention, other toner constituent components such as a colorant, a release agent, and a charge control agent can be further contained as necessary. The toner base particle manufacturing method according to the present invention may be a dry manufacturing method such as a pulverization method, but a wet manufacturing method (for example, an emulsion aggregation method) prepared in an aqueous medium is more preferable.

<Domain matrix structure>
The “domain matrix structure” refers to a structure in which a domain having a closed interface (a boundary between phases) exists in a continuous matrix. The domain matrix structure of the toner base particles according to the present invention has a state in which there is a portion in which the crystalline polyester resin is introduced incompatible with the amorphous resin, that is, in the matrix containing the amorphous resin. In this state, a domain containing a crystalline polyester resin is dispersed. As described above, in the toner base particles according to the present invention, the domain contains the crystalline polyester resin and the matrix contains the amorphous resin.
The domain may contain a lamellar crystal structure. As described in the examples, this structure is obtained by using an electron microscope “JSM-7401F” (manufactured by JEOL Ltd.) of a section of toner particles stained with ruthenium tetroxide (RuO ₄ ). Can be observed. In addition to the crystalline polyester resin, wax or the like may be added in the domain. For example, as in the example described in the column of Examples, observation with an electron microscope “JSM-7401F” (manufactured by JEOL Ltd.) may be performed within 24 hours after staining.

(Crystalline polyester resin)
The domain according to the present invention includes a crystalline polyester resin. “Crystalline polyester resin” means a differential scanning among known polyester resins obtained by polycondensation reaction of divalent or higher carboxylic acid (polyvalent carboxylic acid) and divalent or higher alcohol (polyhydric alcohol). In calorimetry (DSC), it refers to a resin having a clear endothermic peak rather than a stepwise endothermic change.
The clear endothermic peak specifically means a peak in which the half-value width of the endothermic peak is within 15 ° C. when measured at a rate of temperature increase of 10 ° C./min in differential scanning calorimetry (DSC). To do.

In the present invention, the crystalline polyester resin contained in the domain has the carbon number of the main chain of the structural unit derived from the polyhydric alcohol as _Calcohol, and the carbon number of the main chain of the structural unit derived from the polyvalent carboxylic acid. when was the _{C acid,} it is preferable to satisfy the following relational expression (1) and (2). As the difference in the length of the alkyl chain between the alcohol and the acid increases, the crystalline polyester becomes more difficult to aggregate and the crystals can be finely dispersed. For this reason, if it is 5 or more, it can avoid that an excessively large domain is formed, and if it is 12 or less, it can avoid becoming an excessively small domain. Further, by satisfying the relational expressions (1) and (2), it is possible to release a positive charge appropriately, and it is possible to more favorably suppress the occurrence of white spots in the lead due to the scavenging phenomenon.

5 ≦ | C _acid −C _alcohol ≦≦ 12 (1)
_Calcohol <C _acid ... relational expression (2)

  The content of the crystalline polyester resin is preferably in the range of 5 to 20% by mass with respect to the total amount of the resin constituting the toner particles. If content of crystalline polyester resin is 5 mass% or more, generation | occurrence | production of a lead part white-out can be suppressed more. Further, if the content of the crystalline polyester is 20% by mass or less, it is preferable that the aggregation is easily controlled when the toner is produced.

(Melting point of crystalline polyester resin)
The melting point of the crystalline polyester of the present invention is preferably in the range of 60 to 90 ° C, more preferably in the range of 65 to 85 ° C. In the present invention, the melting point of the crystalline polyester resin is a value measured as follows. That is, using a differential scanning calorimeter “Diamond DSC” (manufactured by PerkinElmer Co., Ltd.), a first temperature raising process in which the temperature is raised from 0 ° C. to 200 ° C. at an ascending / descending rate of 10 ° C./min. It is measured by the measurement conditions (temperature rise / cooling conditions) that pass through the cooling process for cooling from 0 to 0 ° C. and the second temperature raising process for raising the temperature from 0 ° C. to 200 ° C. at an elevation rate of 10 ° C./min. Based on the DSC curve obtained by this measurement, the endothermic peak top temperature derived from the crystalline polyester resin in the first temperature raising step is defined as the melting point (Tm). As a measurement procedure, 3.0 mg of a measurement sample (crystalline polyester resin) is sealed in an aluminum pan and set in a diamond DSC sample holder. The reference uses an empty aluminum pan.

(Polyhydric alcohol)
A polyhydric alcohol is a compound containing two or more hydroxy groups in one molecule. Specifically, for example, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1 , 8-octanediol, 1,9-nonanediol, dodecanediol, neopentylglycol, 1,4-butenediol, and other aliphatic diols; trivalent or more polyvalent such as glycerin, pentaerythritol, trimethylolpropane, sorbitol Examples include alcohol. These may be used individually by 1 type and may be used in combination of 2 or more type.

(Polyvalent carboxylic acid)
The polyvalent carboxylic acid is a compound containing two or more carboxy groups in one molecule. Specifically, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tetradacandiol Saturated aliphatic dicarboxylic acids such as cycloaliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid Acid; and anhydrides of these carboxylic acid compounds or alkyl esters having 1 to 3 carbon atoms. These may be used individually by 1 type and may be used in combination of 2 or more type.

(Hybrid crystalline polyester resin)
The crystalline polyester resin contained in the domain is preferably a hybrid crystalline polyester resin in which a styrene / acrylic polymer segment is chemically bonded to a polyester polymer segment (hereinafter also simply referred to as “hybrid resin”).
The hybrid crystalline polyester resin is preferably a crystalline polyester resin in which the styrene / acrylic polymer segment and the polyester polymer segment are bonded via both reactive monomers. By making the crystalline polyester resin a hybrid crystalline polyester resin hybridized with a styrene / acrylic polymer segment, the interface between the domain and the matrix becomes smooth, and negative charges are more easily released. Occurrence of omission can be further suppressed.

(Styrene / acrylic polymer segment)
In the hybrid crystalline polyester resin, the styrene / acrylic polymer segment refers to a portion derived from the styrene / acrylic resin and refers to a molecular chain having the same chemical structure as that constituting the styrene / acrylic resin.
That is, the styrene / acryl polymer segment constituting the hybrid crystalline polyester resin according to the present invention is formed by addition polymerization of at least a styrene monomer and a (meth) acrylate monomer. . Styrene monomer as referred to herein, in addition to styrene represented by the structural formula _{CH 2 = CH-C 6 H} 5, is intended to include a structure having a known side-chain or functional groups styrene structure. In addition, the (meth) acrylic acid ester monomer here is an acrylic acid ester represented by CH ₂ ═CHCOOR (R is an alkyl group) or a methacrylic acid ester, an acrylic acid ester derivative or a methacrylic acid ester. It includes an ester having a known side chain or functional group in the structure of a derivative or the like. In addition, since the styrene monomer and the (meth) acrylic acid ester monomer can use what is mentioned as a monomer which comprises an amorphous vinyl resin similarly, detailed description is carried out here. Is omitted. The content of the styrene / acrylic polymer segment in the hybrid resin is preferably in the range of 0.5 to 20%. Within this range, the occurrence of scavenging can be further suppressed.

(Polyester polymerization segment)
The polyester polymer segment constituting the hybrid crystalline polyester resin according to the present invention is composed of a crystalline polyester resin produced by performing a polycondensation reaction between a polyhydric alcohol and a polycarboxylic acid in the presence of a catalyst. The That is, in the hybrid crystalline polyester resin, the polyester polymerization segment refers to a portion derived from the crystalline polyester resin, and refers to a molecular chain having the same chemical structure as that constituting the crystalline polyester resin. Here, the specific types of the polyhydric alcohol and polyhydric carboxylic acid are as described above, and thus detailed description thereof is omitted here.

(Amotropic monomer)
The “both reactive monomers” according to the present invention is a monomer that binds a polyester polymer segment and a styrene / acryl polymer segment, and in the molecule, a hydroxy group, a carboxy group, an epoxy that forms a polyester polymer segment. It is a monomer having both a group selected from a group, a primary amino group and a secondary amino group, and an ethylenically unsaturated group forming a styrene / acrylic polymerized segment. Both reactive monomers are preferably monomers having a hydroxy group or a carboxy group and an ethylenically unsaturated group. More preferably, it is a monomer having a carboxy group and an ethylenically unsaturated group. That is, it is preferably a vinyl carboxylic acid.
Specific examples of the both reactive monomers include, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, and the like, and these hydroxyalkyl (1 to 3 carbon atoms) esters. However, acrylic acid, methacrylic acid or fumaric acid is preferable from the viewpoint of reactivity. The polyester polymer segment and the styrene / acryl polymer segment are bonded through the both reactive monomers.
The amount of both reactive monomers used is based on 100 parts by mass of the total amount of vinyl monomers constituting the styrene / acryl polymer segment from the viewpoint of improving the low temperature fixability, high temperature offset resistance and durability of the toner. 1-10 mass parts is preferable and 4-8 mass parts is more preferable.

(Method for producing hybrid crystalline polyester resin)
As a method for producing the hybrid crystalline polyester resin, an existing general scheme can be used. The following three methods are listed as typical methods.
(1) A polyester polymerization segment is polymerized in advance, and both reactive monomers are reacted with the polyester polymerization segment, and further, a styrene monomer and (meth) acrylic acid for forming a styrene / acrylic polymerization segment A method of forming a hybrid resin by reacting an ester monomer.
(2) A styrene / acrylic polymer segment is polymerized in advance, a polycarboxylic acid and a polyhydric alcohol for reacting both reactive monomers with the styrene / acrylic polymer segment and further forming a polyester polymer segment A method of forming a polyester polymer segment by reacting.
(3) A method in which a polyester polymerization segment and a styrene / acrylic polymerization segment are respectively polymerized in advance, and both are reacted with each other to react them.

  In the present invention, any of the methods for producing the hybrid crystalline polyester resin can be used, but the method of the above item (2) is preferred. Specifically, the polyvalent carboxylic acid and polyhydric alcohol forming the polyester polymerization segment, the monomer forming the styrene / acryl polymerization segment and the both reactive monomers are mixed, and the polymerization initiator is added to styrene. It is preferable to carry out a polycondensation reaction by adding an esterification catalyst after addition polymerization of a monomer that forms an acrylic polymerization segment and a bireactive monomer to form a styrene / acrylic polymerization segment.

  Here, as a catalyst for synthesizing the polyester polymerization segment, various conventionally known catalysts can be used. In addition, examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamate. An acid etc. are mentioned.

(Amorphous resin)
An amorphous resin refers to a resin having a glass transition temperature (Tg) in an endothermic curve obtained by differential scanning calorimetry (DSC), but having no melting point, that is, a clear endothermic peak at the time of temperature rise.
There is no restriction | limiting in particular about the amorphous resin which the matrix based on this invention contains, A conventionally well-known amorphous resin in this technical field may be used. Among these, it is preferable to contain an amorphous vinyl resin as the amorphous resin. Particularly preferably, the amorphous resin contains a styrene / acrylic resin formed using a styrene monomer, a (meth) acrylic acid ester monomer or acrylic acid. By emulsifying and aggregating styrene / acrylic resin into a toner, the amount of water contained in the toner (hereinafter also simply referred to as “water content”) is moderately high due to the influence of acidic monomers and the influence of aggregated salts. Thus, the adhesion force of the toner to the electrostatic latent image carrier increases. As a result, it becomes difficult for the toner to be detached from the electrostatic latent image carrier, so that the occurrence of the scavenging phenomenon can be suppressed, and further, the occurrence of whitening of the lead portion can be further suppressed.

  As the vinyl monomer that forms the amorphous vinyl resin, one or more selected from the following monomers may be used.

(1) Styrene monomer Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, and derivatives thereof.
(2) (meth) acrylic acid ester monomer (meth) methyl acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, ( T-butyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, (meth) Diethylaminoethyl acrylate, dimethylaminoethyl (meth) acrylate, and derivatives thereof.
(3) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate and the like.
(4) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether and the like.
(5) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.
(6) N-vinyl compounds N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.
(7) Others Vinyl compounds such as vinyl naphthalene and vinyl pyridine, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

Moreover, as a vinyl monomer, it is preferable to use the monomer which has ionic dissociation groups, such as a carboxy group, a sulfonic acid group, and a phosphoric acid group, for example. Specifically, there are the following.
Examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, and the like. Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, and 2-acrylamido-2-methylpropane sulfonic acid. Furthermore, examples of the monomer having a phosphate group include acid phosphooxyethyl methacrylate.

  Furthermore, polyfunctional vinyls can be used as the vinyl monomer, and the amorphous vinyl resin can have a crosslinked structure. Polyfunctional vinyls include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol Examples include diacrylate.

  As mentioned above, although the vinyl resin was demonstrated in detail as a preferable form of an amorphous resin, an amorphous polyester resin etc. may be used as an amorphous resin.

[Other ingredients]
The toner base particles of the present invention may contain an internal additive such as a colorant, a release agent, and a charge control agent, if necessary, in addition to the above components.

[Colorant]
As the colorant according to the present invention, carbon black, a magnetic substance, a dye, a pigment, and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, and the like are used. The Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum and manganese-copper-tin, chromium dioxide, and the like can be used.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include C.I. I. Pigment Red 2, 3, 5, 6, 7, 15, 15, 48: 1, 53: 1, 57: 1, 60, 63, 64, 68, the same 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, 269, and the like.

  Examples of the colorant for orange or yellow include C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, 185, and the like.

  Further, as a colorant for green or cyan, C.I. I. Pigment Blue 2, 3, 15, 15, 15: 2, 15: 3, 15: 4, 16, 17, 17, 60, 62, 66, C.I. I. And CI Pigment Green 7.

  These colorants can be used alone or in combination of two or more as required.

  The addition amount of the colorant is preferably in the range of 1 to 30% by mass, more preferably in the range of 2 to 20% by mass with respect to the total toner, and a mixture thereof can also be used. Within such a range, the color reproducibility of the image can be ensured.

  The size of the colorant is a volume average particle size, for example, in the range of 10 to 1000 nm, preferably in the range of 50 to 500 nm, and more preferably in the range of 80 to 300 nm.

[Release agent]
The release agent according to the present invention is not particularly limited, and known ones can be used. Specifically, for example, polyolefin wax such as polyethylene wax and polypropylene wax, branched chain hydrocarbon wax such as microcrystalline wax, long chain hydrocarbon wax such as paraffin wax and sazol wax, distearyl ketone, etc. Dialkyl ketone wax, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecane Ester wax such as diol distearate, tristearyl trimellitic acid, distearyl maleate, ethylenediamine behenyl amide, tristearyl amide of trimellitic acid And the like amide-based waxes such as.

  Melting | fusing point of a mold release agent becomes like this. Preferably it is 40-160 degreeC, More preferably, it is 50-120 degreeC. By setting the melting point within the above range, heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner is preferably 1 to 30% by mass, more preferably 5 to 20% by mass.

<Charge control agent>
As the charge control agent, various known compounds such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and salicylic acid metal salts can be used. .

  The addition amount of the charge control agent is usually 0.1 to 10% by mass, preferably 0.5 to 5% by mass with respect to 100% by mass of the binder resin in the finally obtained toner base particles. The

  The size of the charge control agent particles is, for example, 10 to 1000 nm, preferably 50 to 500 nm, more preferably 80 to 300 nm in terms of number average primary particle size.

[External additive]
From the viewpoint of controlling the fluidity and chargeability of the toner particles, the toner of the present invention preferably further contains an external additive. Examples of such external additives include silica particles, titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles. And particles such as manganese oxide particles and boron oxide particles (hereinafter also referred to as “external additive particles”).
The number average primary particle size of such external additive particles can be adjusted, for example, by classification or mixing of classified products.
The surface of the external additive particles is preferably subjected to a hydrophobic treatment. A known surface modifier is used for the hydrophobic treatment. Examples of the surface modifier include silane coupling agents, titanate coupling agents, aluminate coupling agents, fatty acids, fatty acid metal salts, esterified products thereof, rosin acids, silicone oils, and the like.

  The addition amount of the external additive in the toner is not particularly limited, but is preferably 0.1 to 10.0% by mass, more preferably 1.0 to 3.0% with respect to 100% by mass of the toner. % By mass.

[Toner Production Method]
The method for producing the toner according to the present invention is not particularly limited, and a known method can be adopted, but an emulsion polymerization aggregation method or an emulsion aggregation method can be preferably employed.

  Further, the emulsion aggregation method preferably used as a method for producing the toner according to the present invention is a method in which resin particles are obtained by removing a solvent after performing a phase inversion emulsification by dropping a poor solvent into a binder resin solution dissolved in a solvent. As a dispersion, this resin particle dispersion is mixed with a colorant dispersion and a release agent dispersion such as wax, and agglomerated until a desired toner particle diameter is obtained. Further, the binder resin fine particles are fused. This is a method for producing toner particles by performing shape control.

An example of using the emulsion aggregation method as a method for producing the toner of the present invention is shown below.
(1) Step of preparing a dispersion liquid in which fine particles of colorant are dispersed in an aqueous medium (2) Dispersion in which binder resin fine particles containing an internal additive are dispersed in an aqueous medium as required Step of preparing liquid (for example, dispersion of amorphous resin fine particles and dispersion of crystalline resin fine particles) (3) Mixing a dispersion of colorant fine particles and a dispersion of binder resin fine particles. A step of agglomerating, associating and fusing the fine particles of the colorant and the binder resin fine particles to form toner base particles. (4) The toner base particles are separated by filtration from the dispersion of the toner base particles (aqueous medium), and the interface Step of removing activator, etc. (5) Step of drying toner base particles (6) Step of adding external additive to toner base particles

  As described above, the toner “particles” are formed by aggregating, associating, and fusing the “fine particles” of the colorant with the binder resin “fine particles” such as the amorphous resin “fine particles” and the crystalline resin “fine particles”. Can be formed.

In the above, the particle diameter of the fine particles of the colorant is preferably 80 to 200 nm.
The particle diameter of the amorphous resin fine particles is preferably in the range of 50 to 300 nm, more preferably in the range of 80 to 300 nm, from the viewpoint of toner performance and production suitability. is there.
Moreover, it is preferable that the particle diameter of the crystalline polyester resin fine particles is, for example, in the range of 30 to 500 nm in terms of volume-based median diameter.
The particle diameters of the colorant fine particles, amorphous resin fine particles, and crystalline resin fine particles are measured by a dynamic light scattering method using “Microtrac UPA-150” (manufactured by Nikkiso Co., Ltd.).

<Developer>
The developer according to the present invention includes a toner and a carrier. Specifically, it is a two-component developer mixed with so-called carrier particles.
The two-component developer can be produced, for example, by appropriately mixing the toner particles and the following carrier particles so that the toner particle content (toner concentration) is 4.0 to 8.0% by mass. it can.
Specific examples of the mixing device used for the mixing include a Nauta mixer, a W cone, and a V-type mixer.

[Career]
The carrier is preferably an aggregate of particles composed of a magnetic material (hereinafter also referred to as “carrier particles”). Examples of the carrier particles include carrier core particles made of the magnetic material and a layer (hereinafter simply referred to as “resin coating layer” or “coating layer”) of a coating material (for example, resin) covering the surface. )) And resin-dispersed carrier particles in which fine powders of a magnetic material are dispersed in a resin. The carrier particles are preferably the coated carrier particles from the viewpoint of suppressing the adhesion of the carrier particles to the photoreceptor.

The resistance of the carrier according to the present invention (so-called “carrier resistance”) is in the range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm. More preferably, it is in the range of 1.0 × 10 ^{9 to} 5.0 × 10 ¹⁰ Ω · cm. If it is 5.0 × 10 ¹⁰ Ω · cm or less, the occurrence of the scavenging phenomenon can be further suppressed.

<Carrier core particles>
Examples of carrier core particles (magnetic particles) include iron powder, magnetite, various ferrite-based particles, or those in which they are dispersed in a resin. Magnetite and various ferrite particles are preferred. As the ferrite, ferrite containing heavy metals such as copper, zinc, nickel and manganese and light metal ferrite containing alkali metals or alkaline earth metals are preferable.

(Volume average particle diameter and saturation magnetization of carrier core particles)
The particle size is 10 to 100 μm, preferably 20 to 80 μm, in terms of volume average particle size. Further, the magnetization characteristic of the magnetic material itself is preferably 2.5 × 10 ^{−5 to} 15.0 × 10 ⁻⁵ Wb · m / kg in saturation magnetization.
The volume average particle size of the carrier core particles is a volume-based average particle size measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser. The saturation magnetization is measured by “DC magnetization characteristic automatic recording device 3257-35” (manufactured by Yokogawa Electric Corporation).

(Method for producing carrier core particles)
After an appropriate amount of the carrier core material raw material is weighed, it is preferably pulverized and mixed in a wet media mill, ball mill, vibration mill or the like for 0.5 hour or more, more preferably for 1 to 20 hours. The pulverized product thus obtained is pelletized using a pressure molding machine or the like, and then calcined at a temperature of preferably 700 to 1200 ° C., preferably for 0.5 to 5 hours. In addition, after pulverizing without using a pressure molding machine, water may be added to form a slurry, and granulated using a spray dryer.

  After calcination, after further pulverization with a ball mill or vibration mill, etc., water and, if necessary, a dispersant, a binder such as polyvinyl alcohol (PVA), etc. are added to adjust the viscosity, and granulation is performed. Is called. The firing temperature is preferably 1000 to 1500 ° C., and the firing time is preferably 1 to 24 hours. When pulverizing after calcination, water may be added and pulverized with a wet ball mill, a wet vibration mill or the like.

The pulverizer such as the above-mentioned ball mill or vibration mill is not particularly limited, but it is preferable to use fine beads having a particle diameter of 1 cm or less for the medium to be used in order to disperse the raw materials effectively and uniformly. Further, the degree of grinding can be controlled by adjusting the diameter, composition and grinding time of the beads used.
The fired product thus obtained is pulverized and classified. As a classification method, the particle size is adjusted to a desired particle size using an existing air classification method, mesh filtration method, sedimentation method, or the like.
Thereafter, if necessary, the surface can be heated at a low temperature to perform an oxide film treatment to adjust the resistance. The oxide film treatment can be performed by heat treatment at, for example, 300 to 700 ° C. using a general rotary electric furnace, batch electric furnace or the like. The thickness of the oxide film formed by this treatment is preferably 0.1 nm to 5 μm. By making the thickness of the oxide film within the above range, the effect of the oxide film layer can be obtained, and it is easy to obtain desired characteristics without becoming too high resistance. If necessary, reduction may be performed before the oxide film treatment. In addition, after classification, low-magnetism products may be further classified by magnetic separation.

(Coating material)
The resin as a coating material suitable for forming the coating layer of the carrier of the present invention is a polyolefin resin such as polyethylene, polypropylene, chlorinated polyethylene, or chlorosulfonated polyethylene; polyacrylate such as polystyrene or polymethyl methacrylate, polyacrylonitrile, polyvinyl Polyvinyl and polyvinylidene resins such as acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone; copolymers such as vinyl chloride-vinyl acetate copolymer and styrene-acrylic acid copolymer; Silicone resin consisting of organosiloxane bond or its modified resin (for example, alkyd resin, polyester resin, epoxy resin, polyurethane, etc.); polytetrachloroethylene Epoxy resins; amino resins such as formaldehyde resins - urea; down, polyvinyl fluoride, polyvinylidene fluoride, chloro tri full Lol ethylene and fluorine resins, polyamides, polyesters, polyurethanes, polycarbonates. Preference is given to polyacrylate resins, which are obtained by polymerizing monomers containing an alicyclic (meth) acrylic ester.

By including such a resin, the hydrophobicity of the coating layer is increased, and the moisture adsorption amount of the carrier particles is decreased particularly under high temperature and high humidity. Therefore, a decrease in the charge amount of the carrier under high temperature and high humidity is suppressed. Moreover, since the above-mentioned resin has a rigid cyclic skeleton, the film strength (mechanical strength) of the coating layer is improved, and the durability of the carrier is improved.
Further, a copolymer of alicyclic (meth) acrylic acid ester and methyl methacrylate is more preferable. This is because the film strength is further increased by using methyl methacrylate.

  The alicyclic (meth) acrylic acid ester is a cycloalkyl having 5 to 8 carbon atoms from the viewpoint of mechanical strength, environmental stability of charge amount (small environmental difference of charge amount), ease of polymerization and availability. It preferably has a group. The alicyclic (meth) acrylic acid ester is at least one selected from the group consisting of cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate. It is preferable that Among these, from the viewpoint of the mechanical strength and the environmental stability of the charge amount, it is preferable to contain cyclohexyl (meth) acrylate.

In the resin, the content of the structural unit derived from the alicyclic (meth) acrylic acid ester is preferably 10 to 100% by mass, and more preferably 20 to 100% by mass. Within such a range, the environmental stability and durability of the charge amount of the carrier are further improved.
The number of parts of the resin added to the core particles is preferably in the range of 1 to 5 parts by mass. More preferably within the range of 1.5 to 4 parts by mass. If it is 1 part by mass or more, the charge amount can be more suitably maintained. Moreover, if it is 5 mass parts or less, it can avoid that carrier resistance becomes high too much.

(Coating method)
As a specific method for forming the coating layer, a known method can be used, and examples thereof include a wet coating method and a dry coating method. Each method will be described below. The dry coating method is a particularly desirable method to be applied to the present invention, and will be described in more detail. However, the coating method is not limited to the following method.

Examples of the wet coating method include the following.
(1) Fluidized bed spray coating method For example, a coating solution in which a resin as a coating material is dissolved in a solvent is applied to the surface of magnetic particles using a fluidized bed, and then dried to form a coating layer. Method

(2) Immersion coating method A method in which magnetic particles are immersed in a coating solution in which a coating resin is dissolved in a solvent, followed by coating treatment, and then dried to form a coating layer.

(3) Polymerization method The magnetic particles are immersed in a coating solution in which a reactive compound is dissolved in a solvent, and coating is performed. Next, a method of forming a coating layer by performing a polymerization reaction by adding heat or the like can be exemplified.

(4) Dry coating method Resin particles are deposited as a coating material on the surface of carrier core material particles to be coated. Thereafter, a mechanical impact force is applied, and the resin particles deposited on the surface of the carrier particles are fixed by melting or softening to form a coating layer.
Specifically, a mixture of carrier core material particles, resin particles, low-resistance fine particles, and the like is stirred at high speed using a high-speed stirring mixer that can impart mechanical impact force without heating or under heating. Thereby, an impact force is repeatedly applied to the above mixture, and resin particles or the like are dissolved or softened and fixed to the surface of the carrier core material particles to produce a carrier having a coating layer.
The dry coating conditions are preferably 80 to 130 ° C. when heating, and the wind speed for generating impact force is preferably 10 m / s or more during heating, and 5 m to suppress aggregation between carriers during cooling. / S or less is preferable. The time for applying the impact force is preferably 20 to 60 minutes.

(Carrier resistance)
The resistance (carrier resistance) of the carrier according to the present invention is in the range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm. Preferably, it is in the range of 1.0 × 10 ^{9 to} 5.0 × 10 ¹⁰ Ω · cm.
When it is less than 1.0 × 10 ⁹ Ω · cm, carrier adhesion occurs. On the other hand, if it is higher than 1.0 × 10 ¹¹ Ω · cm, it is not possible to sufficiently prevent the occurrence of white spots in the lead due to the scavenging phenomenon.

  The carrier resistance according to the present invention refers to the electrical resistivity of the initial carrier, and is the electrical resistivity of the carrier from which the toner is separated from the developer at the start of use of the carrier. The carrier resistance according to the present invention is dynamically measured under the developing conditions with a magnetic brush as described below.

(Measurement of carrier resistance)
An aluminum electrode drum having the same dimensions as the photosensitive drum is replaced with a photosensitive drum, a carrier is supplied onto the developing sleeve to form a magnetic brush, and the magnetic brush is rubbed against the electrode drum. By applying a voltage (500 V) between them and measuring the current flowing between them, the carrier resistance was determined by the following formula 3.
DVR (Ω · cm) = (V / I) × (N × L / Dsd) (Formula 3)
DVR: Carrier resistance (Ω · cm)
V: Voltage between developing sleeve and drum (V)
I: Measurement current value (A)
N: Development nip width (cm)
L: Development sleeve length (cm)
DSD: Distance between developing sleeve and drum (cm)
In the present invention, the measurement is performed at V = 500 V, N = 1 cm, L = 6 cm, and Dsd = 0.6 mm.

(Carrier (particle) particle size (volume average particle size))
The volume average diameter of the carrier (particles) is preferably 10 to 100 μm, more preferably 20 to 80 μm. The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathec) equipped with a wet disperser.

[Charging means, exposure means, developing means using developer containing toner and carrier, transfer means, fixing means, cleaning means]
Hereinafter, an electrophotographic image forming apparatus having other configurations including a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and a cleaning unit according to the present invention will be described with reference to FIGS.
FIG. 3 is a schematic cross-sectional view of an electrophotographic image forming apparatus adopting a normal rotation developing system as an example of an electrophotographic image forming apparatus (hereinafter also simply referred to as “image forming apparatus”) according to the present invention. FIG. 4 is a schematic cross-sectional view showing an example of a developing device according to the electrophotographic image forming apparatus of FIG.

  In FIG. 3, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus YS.

  The image forming apparatus main body GH is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a sheet feeding and conveying unit, and a fixing device 24. It consists of.

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 8Y disposed around a photosensitive drum 1Y as an image carrier. The image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 8M. The image forming unit 10C that forms a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 8C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported. Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred (primary transfer) by the transfer means 7Y, 7M, 7C, and 7K onto the rotating intermediate transfer body 6 to be synthesized. A color image is formed. The recording paper P stored in the paper feeding cassette 20 is fed by the paper feeding means 21 and is conveyed to the transfer means 7A via the paper feeding rollers 22A, 22B, 22C, the registration rollers 23, etc. A color image is transferred to (secondary transfer). The recording paper P onto which the color image has been transferred is fixed by a fixing device 24 serving as a fixing unit, and is sandwiched between paper discharge rollers 25 and placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording paper P by the transfer means 7A, the residual toner is removed by the cleaning means 8A from the intermediate transfer body 6 from which the recording paper P is separated by curvature.

  4Y, 4M, 4C, and 4K are developing units that contain a two-component developer composed of a toner having a small particle diameter and a carrier of yellow (Y), magenta (M), cyan (C), and black (K). Reference numerals 5Y, 5M, 5C, and 5K denote toner supply units that supply new toner to the developing devices 4Y, 4M, 4C, and 4K, respectively.

  An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the image forming apparatus main body GH. The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 202, and is applied to the line image sensor CD. Is read.

  The analog signal photoelectrically converted by the line image sensor CD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in an image processing unit, and then image writing units (exposure means) 3Y, 3M, 3C. Send a signal to 3K.

  The automatic document feeder 201 includes automatic double-sided document conveying means. The automatic document feeder 201 can continuously read the contents of a large number of documents d fed from the document table and store them in the storage means (electronic RDH function). This is convenient when copying the contents of a large number of originals by the function or when transmitting a large number of originals d by the facsimile function.

  In addition, a temperature / humidity sensor S as an environmental condition detection unit for detecting an environmental condition is provided in the image forming apparatus main body GH. In addition, a number counter for counting the number of copies connected to the development control unit is provided in the image forming apparatus main body GH.

Next, the developing devices 4Y, 4M, 4C, and 4K are represented as the developing devices 4, and the photosensitive drums 1Y, 1M, 1C, and 1K are represented as the photosensitive drums 1 in the present invention with reference to FIG. The developing means (developing device) using the developer containing such toner and carrier will be described below.
Here, in the present invention, the developing means may be a means for developing by the above-described normal development method. According to the present invention, it is possible to effectively suppress the occurrence of white spots in the lead portion and carrier adhesion even with a means for developing by the forward developing method.
An example shown in FIG. 4 will be described below as an example of means for developing by the forward development method that can be used in the present invention. However, the means for developing of the present invention is not limited to this, and a known one is used. Can be used.
In the following description, the two-component developer is also referred to as a developer. Also, the black filled arrow indicates the direction of supplying and transporting the two-component developer to the developer carrier, and the white arrow indicates the direction of peeling and collecting the two-component developer from the developer carrier. .

  The developing device 4 is composed of a developing device frame 40, a developing roller 41 as a developer carrying member, a magnetic field generating means (magnet roll) 42, a regulating means 43 made up of a scissor plate, a water wheel type supply means 44, and a screw. A stirring screw 45, 46 for carrying, a peeling roller 47, a peeling plate 48, a collecting means 49 including a screw, a toner concentration detection sensor D, and the like.

  The electrostatic latent image is developed in the development region DR by the counterclockwise rotation of the peripheral speed Vp indicated by the arrow of the photosensitive drum 1 and the clockwise rotation of the peripheral speed Vs indicated by the arrow of the developing roller 41. A developing bias in which a DC bias having the same polarity as that of the latent image is superimposed on the AC bias is applied to the developing roller 41 by a bias power source BS, and development is performed.

  The developing roller 41 is disposed to face the photosensitive drum 1 carrying the electrostatic latent image, and is rotatably supported. The developing roller 41 rotates as indicated by an arrow to convey the developer to the developing region DR, and develop A developer layer necessary for development is formed by supporting the developer in the region DR.

≪Process cartridge≫
The electrophotographic image forming apparatus of the present invention includes the electrophotographic photosensitive member of the present invention and the above-described charging unit (charging unit), exposure unit (exposure unit), developing unit (developing unit), or cleaning unit (cleaning unit). It is preferable to configure as a process cartridge (image forming unit) integrally including at least one, and to configure this image forming unit so that it can be taken in and out (detachable) with respect to the main body of the electrophotographic image forming apparatus. In addition to a charging unit, an exposure unit, a developing unit, a process cartridge (image forming unit) having at least one of a transfer unit (transfer unit) and a separation unit (separator) together with a photosensitive member is formed. A single image forming unit that is detachable from the main body may be used, and a structure that is detachable by using a guide means such as a rail of the apparatus main body may be used.

  The electrophotographic image forming apparatus of the present invention is generally applicable to electrophotographic image forming apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, but also displays, recordings, and light printing using electrophotographic technology. It can also be widely applied to apparatuses such as plate making and facsimile.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

-Production of N-type semiconductor particles (Production of N-type semiconductor particles 1)
Using the N-type semiconductor particle manufacturing apparatus shown in FIG. 5, N-type semiconductor particles 1 in which tin oxide was adhered to the surface of the barium sulfate core material were produced. Specifically, 3500 cm ³ of pure water was introduced into the mother liquor 11, and then 900 g of a spherical barium sulfate core material having a volume-based median diameter D ₅₀ of 50 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor 11 was 2280 cm ³ / min. The stirring speed of the strong dispersion device 13 was set to 16000 rpm. After completion of the circulation, the slurry was made up to a total volume of 9000 cm ³ with pure water, and 700 g of sodium stannate and 2.3 cm ³ of an aqueous sodium hydroxide solution (concentration 25 mol / L) were added thereto and circulated for 5 passes. A mother liquor was thus obtained. While this mother liquor was circulated so that the flow rate S1 flowing out from the mother liquor tank 11 was 200 cm ^{3 /} min, 20% sulfuric acid was supplied to the homogenizer “magic LAB” (manufactured by IKA Japan Co., Ltd.) as the strong dispersion device 13. . The supply rate S3 was set to 9.2 cm ³ / min. The volume of the homogenizer was 20 cm ³ , and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this manner, particles having a tin oxide coating layer formed on the surface of the barium sulfate core material were obtained.

The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in a 1% by volume H ₂ / N ₂ atmosphere. Thus, N-type semiconductor particles 1 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 1 had a number average primary particle size of 100 nm and a volume resistivity of 8.1 × 10 ⁵ Ω · cm.

  Here, in the N-type semiconductor particle manufacturing apparatus shown in FIG. 5, reference numerals 12 and 14 are circulation pipes that form a circulation path between the mother liquor tank 11 and the strong dispersion apparatus 13, and reference numerals 15 and 16 are circulation pipes 12. , 14, reference numeral 11 a indicates a stirring blade, reference numeral 13 a indicates a stirring portion, reference numerals 11 b and 13 b indicate shafts, and reference numerals 11 c and 13 c indicate motors.

(Measurement method of average primary particle size)
The average primary particle size of the N-type semiconductor particles was calculated from photographic images obtained by observing and photographing the N-type semiconductor particles with a transmission electron microscope. Specifically, the microscope magnification is set to 10,000 times, photography is performed, the horizontal ferret diameter of 100 fine particles is measured by image analysis processing, an average value is calculated, and this is referred to as the number average primary particle size. did. The image analysis process was automatically performed by driving a program built in the transmission electron microscope measurement apparatus. In this example, a transmission electron microscope “JEM-2000FX” (manufactured by JEOL Ltd.) was used to measure the particle size of the fine particles.

(Measurement method of volume resistivity of N-type semiconductor particles)
A sample (N-type semiconductor particles) was filled in a container having electrodes arranged in parallel at an interval of 2 mm, and the DC resistance at a potential difference of 500 V between the two electrodes was measured with a 4329A High Resistance Meter manufactured by Hewlett-Packard Japan.
Cross-sectional area = W × t
Resistance R = V / I
Volume resistivity VR (Ω · cm) = (W × t / L) × (V / I)

(Preparation of N-type semiconductor particles 2)
To 3 L of pure water, 0.1 L of hydrochloric acid having a concentration of 35% by mass was added and heated to 75 ° C. In this hydrochloric acid acidic solution, 300 g of a barium sulfate core material having a volume-based median diameter D ₅₀ of 20 nm is suspended. While stirring, an aqueous solution of titanium tetrachloride (50% by mass as Ti content) is added to 36 g per hour. The caustic soda dissolved in 10% by mass was added at a rate of 360 mL per hour. The slurry containing the obtained particles is repulp washed until the electrical conductivity becomes 100 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake, followed by vacuum drying at 150 ° C., and titanium oxide on the surface of the alumina core material. As a result, N-type semiconductor particles 2 were obtained. The N-type semiconductor particles 2 had a number average primary particle size of 100 nm and a volume resistivity of 7.5 × 10 ⁵ Ω · cm.

(Preparation of N-type semiconductor particles 3)
Using the N-type semiconductor particle manufacturing apparatus shown in FIG. 5, N-type semiconductor particles 3 in which zinc oxide was adhered to the surface of the barium sulfate core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor 11, and then 900 g of a spherical barium sulfate core material having a volume-based median diameter D ₅₀ of 70 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor 11 was 2280 cm ³ / min. The stirring speed of the strong dispersion device 13 was set to 16000 rpm. After completion of the circulation, the slurry was made up to a total volume of 9000 cm ³ with pure water, and 300 g of anhydrous zinc chloride was added thereto and circulated for 5 passes. A mother liquor was thus obtained. A 20% aqueous sodium hydroxide solution is supplied to a homogenizer “T50” (manufactured by IKA Japan Co., Ltd.) as the strong dispersion device 13 while circulating this mother liquor so that the flow rate S1 flowing out from the mother liquor tank 11 is 10 L / min did. The supply rate S3 was 9.2 cm ³ / min, and the pH was 5.0 (liquid temperature was 25 ° C.). The volume of the homogenizer was 500 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this way, particles having a zinc oxide coating layer formed on the surface of the barium sulfate core material were obtained.
The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in the air. As a result, N-type semiconductor particles 3 in which zinc oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 3 had a number average primary particle size of 100 nm and a volume resistivity of 6.9 × 10 ⁵ Ω · cm.

(Preparation of N-type semiconductor particles 4)
Using the N-type semiconductor particle manufacturing apparatus shown in FIG. 5, N-type semiconductor particles 4 in which a composite oxide of indium and tin (indium tin oxide (ITO)) was attached to the surface of the barium sulfate core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor 11, and then 900 g of a spherical barium sulfate core material having a volume-based median diameter D ₅₀ of 80 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor 11 was 2280 cm ³ / min. The stirring speed of the strong dispersion device 13 was set to 16000 rpm. The slurry after the circulation was made up to a total volume of 9000 cm ³ with pure water, and 1 g of tin chloride hydrochloric acid solution (44%) and 244 g of indium nitrate aqueous solution (100 g / 1000 cm ³ , specific gravity 1.6 g / cm ³ ) Sodium stannate was added and circulated for 5 passes. A mother liquor was thus obtained. While this mother liquor was circulated so that the flow rate S1 flowing out from the mother liquor tank 11 was 10 L / min, 20% sodium hydroxide was supplied to a homogenizer “T50” (manufactured by IKA Japan Co., Ltd.) as the strong dispersion device 13. . The supply rate S3 was 9.2 cm ³ / min, and the pH at a liquid temperature of 25 ° C. was 3.0. The volume of the homogenizer was 500 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this way, particles were obtained in which a coating layer of indium and tin hydroxide was formed on the surface of the barium sulfate core material. The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in a 1% by volume H2 / N2 atmosphere. Thus, N-type semiconductor particles 4 in which a composite oxide (ITO) of indium and tin was attached to the surface of the barium sulfate core material were obtained. The number average primary particle size of the N-type semiconductor particles 4 was 100 nm, and the volume resistivity was 8.5 × 10 ⁵ Ω · cm.

(Preparation of N-type semiconductor particles 5)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core material was changed to barium sulfate core median diameter D ₅₀ is 65nm on a volume basis, other due to changes in their sodium stannate amount 550g in the same manner Thus, N-type semiconductor particles 5 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The number-average primary particle size of the N-type semiconductor particles 5 was 100 nm, and the volume resistivity was 8.9 × 10 ⁶ Ω · cm.

(Preparation of N-type semiconductor particles 6)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core material was changed to barium sulfate core median diameter D ₅₀ is 35nm on a volume basis, other due to changes in their sodium stannate amount 1000g in the same manner Thus, N-type semiconductor particles 6 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 6 had a number average primary particle size of 100 nm and a volume resistivity of 2.1 × 10 ⁴ Ω · cm.

(Preparation of N-type semiconductor particles 7)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core material was changed to barium sulfate core median diameter D ₅₀ is 200nm on a volume basis, other due to changes in their sodium stannate amount 700g in the same manner Thus, N-type semiconductor particles 7 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 7 had a number average primary particle size of 290 nm and a volume resistivity of 5.5 × 10 ⁵ Ω · cm.

(Preparation of N-type semiconductor particles 8)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core changes median diameter D ₅₀ of the volume based on the barium sulfate core is 35 nm, other due to changes in their sodium stannate amount 550g in the same manner Thus, N-type semiconductor particles 8 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 8 had a number average primary particle size of 55 nm and a volume resistivity of 7.4 × 10 ⁵ [Ω · cm].

(Preparation of N-type semiconductor particles 9)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core material was changed to barium sulfate core median diameter D ₅₀ is 85nm on a volume basis, other due to changes in their sodium stannate amount 400g in the same manner Thus, N-type semiconductor particles 9 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The number-average primary particle size of the N-type semiconductor particles 9 was 100 nm, and the volume resistivity was 2.5 × 10 ⁷ Ω · cm.

(Preparation of N-type semiconductor particles 10)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core, the median diameter D ₅₀ of the volumetric basis is changed to barium sulfate core is 25 nm, other due to changes in their sodium stannate amount 1300g in the same manner Thus, N-type semiconductor particles 10 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 10 had a number average primary particle size of 100 nm and a volume resistivity of 8.7 × 10 ³ Ω · cm.

(Preparation of N-type semiconductor particles 11)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core changes median diameter D ₅₀ of the volume based on the barium sulfate core is 220 nm, the other due to changes in their sodium stannate amount 700g in the same manner Thus, N-type semiconductor particles 11 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The N-type semiconductor particles 11 had a number average primary particle size of 310 nm and a volume resistivity of 8.7 × 10 ³ Ω · cm.

(Preparation of N-type semiconductor particles 12)
In the preparation of the N-type semiconductor particles 1, the barium sulfate core material was changed to barium sulfate core median diameter D ₅₀ is 30nm on a volume basis, other due to changes in their sodium stannate amount 700g in the same manner Thus, N-type semiconductor particles 12 in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The number average primary particle size of the N-type semiconductor particles 12 was 40 nm, and the volume resistivity was 5.2 × 10 ⁵ Ω · cm.

[Production of photoconductor]
<Preparation of Photoreceptor 1>
The surface of an aluminum cylinder having a diameter of 60 mm was cut to prepare a conductive support 1 having a fine and rough surface.

(Formation of intermediate layer)
A dispersion having the following composition is diluted twice with the same solvent (namely, methanol) as the following solvent, allowed to stand overnight and then filtered (filter; using a lymesh 5 μm filter manufactured by Nihon Pall Co., Ltd.). 1 was prepared.
Binder resin: Polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) 1 part by mass Metal oxide particles: Titanium oxide “SMT500SAS” (manufactured by Teica) 3 parts by mass Solvent: Methanol 10 parts by mass Using a sand mill as a disperser, batch type Then, dispersion was performed for 10 hours to prepare a dispersion having the above composition.
The intermediate layer 1 having a dry film thickness of 2 μm was formed on the conductive support 1 using the intermediate layer forming coating solution 1 by dip coating.

(Formation of charge generation layer)
Charge generation material: 20 parts by mass of the following pigment (CG-1), binder resin: 10 parts by mass of polyvinyl butyral resin “# 6000-C” (manufactured by Denki Kagaku Kogyo), solvent: 700 parts by mass of t-butyl acetate, solvent: 300 parts by mass of 4-methoxy-4-methyl-2-pentanone was mixed and dispersed for 10 hours using a sand mill to prepare a coating solution 1 for forming a charge generation layer. This charge generation layer forming coating solution 1 was applied onto the intermediate layer 1 by a dip coating method to form a charge generation layer 1 having a dry film thickness of 0.3 μm.

(Synthesis of Pigment (CG-1))
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 parts by mass are dispersed in 200 parts by mass of o-dichlorobenzene, and titanium tetra-n-butoxide; 20.4 parts by mass are added. It heated at 150-160 degreeC for 5 hours under nitrogen atmosphere. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 parts by mass (yield 91%) of crude titanyl phthalocyanine.

Next, the crude titanyl phthalocyanine was dissolved by stirring for 1 hour in 250 parts by mass of concentrated sulfuric acid at 5 ° C. or less, and this was poured into 5000 parts by mass of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 parts by mass of a wet paste product.
This wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts by mass of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine 10.0 parts by mass of the above amorphous titanyl phthalocyanine and 0.94 parts by mass of (2R, 3R) -2,3-butanediol ( (0.6 equivalent ratio) (equivalent ratio is equivalent ratio to titanyl phthalocyanine, hereinafter the same) was mixed in 200 parts by mass of orthodichlorobenzene (ODB) and heated and stirred at 60 to 70 ° C. for 6.0 hours. After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The crystals after filtration were washed with methanol to obtain 10.3 parts by mass of Pigment CG-1. In the X-ray diffraction spectrum of the pigment (CG-1), there are clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. In addition, since there is a mass loss of about 7% at 390 to 410 ° C. in thermal analysis (Tg), 1: 1 adduct and non-adduct (addition) of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol (Not) presumed to be a mixture of titanyl phthalocyanine.

It was 31.2 m < ² > / g when the BET specific surface area of the obtained pigment (CG-1) was measured with the flow type specific surface area automatic measuring apparatus (Micrometrics flow soap type: Shimadzu Corporation).

(Formation of charge transport layer)
Charge transport material: 225 parts by mass of the following compound A, binder resin: 300 parts by mass of polycarbonate resin “Z300” (manufactured by Mitsubishi Gas Chemical Company), antioxidant: “Irganox 1010” (manufactured by BASF Japan) 6 parts by mass, solvent: 1600 parts by weight of THF (tetrahydrofuran), 400 parts by weight of toluene, and 1 part by weight of silicone oil “KF-50” (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and dissolved to prepare a coating solution 1 for forming a charge transport layer.
The charge transport layer forming coating solution 1 was applied onto the charge generation layer 1 using a circular slide hopper coating apparatus to form a charge transport layer 1 having a dry film thickness of 20 μm.

(Formation of surface protective layer)
N-type semiconductor particles 1: 120 parts by mass, polyfunctional radical polymerizable compound: 100 parts by mass of the following compound (M1), solvent: 320 parts by mass of 2-butanol, solvent: 80 parts by mass of tetrahydrofuran are mixed in a light-shielded state. As a dispersion for 5 hours using a sand mill, charge transporting compound: 20 parts by mass of the following exemplified compound (CTM-8), polymerization initiator: 10 parts by mass of the exemplified compound (P2) are added, and the mixture is stirred under light shielding. Dissolved to prepare a coating solution 1 for forming a surface protective layer. The surface protective layer forming coating solution 1 is applied onto the charge transport layer 1 using a circular slide hopper coating apparatus to form a coating film, and irradiated with ultraviolet rays for 1 minute using a metal halide lamp, resulting in a dry film thickness of 5 A surface protective layer 1 having a thickness of 0.0 μm was formed to produce a photoreceptor 1.

(Production of photoconductors 2 to 13)
Photoconductors 2 to 13 were prepared in the same manner except that the N-type semiconductor particles in Table I below were changed in the production of the photoconductor 1.
The physical properties of the photoconductors 1 to 13 are summarized in Table I.

<Creation of carrier>
(Preparation of carrier core particles)
A proper amount of each raw material is blended so as to be 19.0 mol% in terms of MnO, 2.8 mol% in terms of MgO, 1.5 mol% in terms of SrO, and 75.0 mol% in terms of Fe2O3, and water is added. Crushing, mixing and drying for 10 hours in a wet ball mill, holding at 950 ° C. for 4 hours, and then granulating and drying the slurry that has been ground for 24 hours in a wet ball mill. A split amount was added and held at a peripheral speed of 10 m / s and 1300 ° C. for 4 hours, and then crushed, and the particle size was adjusted to a particle size of 35 mm to obtain carrier core particles.

(Preparation of carrier 1)
Stirring 100 parts by mass of the carrier core particles prepared above and 2.7 parts by mass of copolymer resin fine particles (coating resin particles) of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5). Put into a high-speed mixer with blades, stir and mix at 125 ° C. for 45 minutes at a wind speed of 10 M / S to form a resin coating layer on the surface of the core particles by the action of mechanical impact force, then lower the wind speed to 2 M / S Then, cooling was performed to prepare “Carrier 1” coated with resin. The carrier resistance was 7.2 × 10 ⁹ Ω · cm.

(Measurement method of carrier resistance)
An aluminum electrode drum having the same dimensions as the photosensitive drum is replaced with a photosensitive drum, a carrier is supplied onto the developing sleeve to form a magnetic brush, and the magnetic brush is rubbed against the electrode drum. By applying a voltage (500 V) between them and measuring the current flowing between them, the carrier resistance was determined by the following formula 3.
DVR (Ω · cm) = (V / I) × (N × L / Dsd) (Formula 3)
DVR: Carrier resistance (Ω · cm)
V: Voltage between developing sleeve and drum (V)
I: Measurement current value (A)
N: Development nip width (cm)
L: Development sleeve length (cm)
DSD: Distance between developing sleeve and drum (cm)
In this example, measurement was performed at V = 500 V, N = 1 cm, L = 6 cm, and Dsd = 0.6 mm.

(Production of carriers 2 to 7)
Carriers 2 to 7 were obtained in the same manner as in Carrier 1 except that the number of parts by mass of the coated resin particles was changed as shown in Table II.

<Production of toner>
(Preparation of crystalline polyester dispersion)
(Synthesis of crystalline polyester resin 1)
281 parts by mass of tetradecanedioic acid as a polyvalent carboxylic acid compound and 283 parts by mass of 1,6-hexanediol as a polyhydric alcohol compound, a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, which are materials for the polyester polymerization segment It put into the equipped reaction container, and it heated to 160 degreeC and made it melt | dissolve.
On the other hand, 23.5 parts by mass of styrene, 6.5 parts by mass of n-butyl acrylate, 2.5 parts by mass of dicumyl peroxide, and acrylic acid as both reactive monomers, which are materials of the vinyl polymerization segment mixed in advance. 2 parts by mass of the solution was added dropwise using a dropping funnel over 1 hour. Stirring was continued for 1 hour while maintaining at 170 ° C., and after polymerizing styrene, n-butyl acrylate and acrylic acid, 2.5 parts by mass of tin (II) 2-ethylhexanoate, 0.2 parts by mass of gallic acid Was added, the temperature was raised to 210 ° C., and the reaction was performed for 8 hours. Furthermore, reaction was performed at 8.3 kPa for 1 hour to obtain a hybridized crystalline polyester resin 1. The amount of introduction of the hybrid part was approximately 5.0%.

(Synthesis of crystalline polyester resin 2)
In the synthesis of the crystalline polyester resin 1, the crystalline polyester resin 2 was synthesized in the same manner except that 1,9-nonanediol was used instead of 1,6-hexanediol as the polyhydric alcohol compound.

(Synthesis of crystalline polyester resin 3)
In the synthesis of the crystalline polyester resin 1, the crystalline polyester resin 3 was synthesized in the same manner except that 1,3-propanediol was used instead of 1,6-hexanediol as the polyhydric alcohol compound.

(Synthesis of crystalline polyester resin 4)
In the synthesis of the crystalline polyester resin 1, dodecanedioic acid is used instead of tetradecanedioic acid as the polyvalent carboxylic acid compound, and 1,9-nonanediol is used instead of 1,6-hexanediol as the polyvalent alcohol compound. A crystalline polyester resin 4 was synthesized in the same manner except for the above.

(Synthesis of crystalline polyester resin 5)
In the synthesis of the crystalline polyester resin 1, octadecanedioic acid is used instead of tetradecanedioic acid as the polyvalent carboxylic acid compound, and 1,4-butanediol is used instead of 1,6-hexanediol as the polyhydric alcohol compound. A crystalline polyester resin 5 was synthesized in the same manner except for the above.

(Synthesis of crystalline polyester resin 6)
281 parts by mass of tetradecanedioic acid as a polyvalent carboxylic acid compound and 283 parts by mass of 1,6-hexanediol as a polyhydric alcohol compound are placed in a reaction vessel equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. Heat to 0 ° C. to dissolve. 2.5 parts by mass of tin (II) 2-ethylhexanoate and 0.2 parts by mass of gallic acid were added, the temperature was raised to 210 ° C., and the reaction was performed for 8 hours. Furthermore, reaction was performed at 8.3 kPa for 1 hour, and the crystalline polyester resin 6 was obtained.

(Synthesis of crystalline polyester resin 7)
In the synthesis of the crystalline polyester resin 6, a crystalline polyester resin 7 was synthesized in the same manner except that decanedioic acid was used as the polyvalent carboxylic acid compound instead of tetradecanedioic acid.

<Preparation of crystalline resin fine particle dispersion>
(Preparation of crystalline resin fine particle dispersions 1 to 7)
About each crystalline polyester resin 1-7 obtained above, 100 mass parts was dissolved in 400 mass parts of ethyl acetate, respectively. Next, 25 parts by mass of a 5.0% aqueous sodium hydroxide solution was added to prepare a crystalline resin solution. While this crystalline resin solution was put into a container having a stirring device and stirred, 638 parts by mass of a 0.26% sodium lauryl sulfate aqueous solution was added dropwise over 30 minutes. During the dropwise addition of the sodium lauryl sulfate aqueous solution, the liquid in the reaction vessel became cloudy, and after adding the entire amount of the sodium lauryl sulfate aqueous solution, an emulsion was prepared in which the crystalline resin fine particles were uniformly dispersed. Next, the emulsion is heated to 40 ° C., and by using a diaphragm vacuum pump “V-700” (manufactured by BUCHI), ethyl acetate is distilled off under a reduced pressure of 150 hPa. Crystalline resin fine particle dispersions 1 to 7 obtained by dispersing the crystalline resin fine particles were obtained.

<Preparation of amorphous resin fine particle dispersion 1>
First-stage polymerization A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device is charged with a solution obtained by dissolving 4 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 parts by mass of ion-exchanged water. The internal temperature was raised to 80 ° C. while stirring and stirring at a stirring speed of 230 rpm under a nitrogen stream. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water was added to obtain a liquid temperature of 75 ° C.
-Styrene 584 parts by mass-N-butyl acrylate 160 parts by mass-A monomer mixture consisting of 56 parts by mass methacrylic acid is added dropwise over 1 hour, followed by polymerization while heating and stirring at 75 ° C for 2 hours. Thus, a dispersion of resin fine particles [b1] was prepared.

Second-stage polymerization A solution prepared by dissolving 2 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 parts by mass of ion-exchanged water in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing apparatus First, the internal temperature was raised to 80 ° C. Next, 42 parts by mass (in terms of solid content) of the dispersion of resin fine particles [b1] obtained above and 70 parts by mass of microcrystalline wax “HNP-0190” (manufactured by Nippon Seiwa Co., Ltd.)
Styrene 239 parts by mass n-butyl acrylate 111 parts by weight methacrylic acid 26 parts by mass n-octyl mercaptan 3 parts by mass A solution prepared by dissolving at 80 ° C in a monomer mixture was added to the circulation path. A dispersion containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.).
Next, an initiator solution in which 5 parts by mass of potassium persulfate is dissolved in 100 parts by mass of ion-exchanged water is added to this dispersion, and this system is heated and stirred at 80 ° C. for 1 hour to perform polymerization. A dispersion of resin fine particles [b2] was prepared.

Third stage polymerization A solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to the dispersion of resin fine particles [b2] obtained above.
-Styrene 380 mass parts-N-butyl acrylate 132 mass parts-Methacrylic acid 39 mass parts-N-octyl mercaptan 6 mass parts monomer mixture was dripped over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to prepare amorphous resin fine particle dispersion 1.

(Preparation of Toner 1)
<Aggregation / fusion process>
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 300 parts by mass (solid content conversion) of amorphous resin fine particle dispersion 1 and 34 parts by mass (solids) of crystalline resin fine particle dispersion 1 are obtained. ), 1100 parts by mass of ion-exchanged water and 40 parts by mass of a colorant fine particle dispersion [Bk] (in terms of solids) were prepared, and after adjusting the liquid temperature to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added. The pH was adjusted to 10. Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. The temperature was raised after holding for 3 minutes, and the temperature of the system was raised to 85 ° C. over 60 minutes, agglomerating while maintaining 85 ° C., and the particle growth reaction was continued. In this state, the particle size of the aggregated particles was measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and when the volume-based median diameter D ₅₀ reached 6 μm, 40 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 160 parts by mass of the exchange water is added to stop the particle growth, and further, as a ripening step, the particles are heated and stirred at a liquid temperature of 80 ° C. for 1 hour, whereby the fusion between the particles proceeds. A dispersion of base particles 1 was prepared.

<Washing and drying process>
The dispersion of toner base particles 1 prepared above is solid-liquid separated with a basket-type centrifuge “MARK III model number 60 × 40 + M” (manufactured by Matsumoto Machinery Co., Ltd.) to form a wet cake of toner base particles 1 did. The wet cake was washed with ion exchange water at 40 ° C. using the basket type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm, and then the “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles 1 were prepared by transferring and drying until the water content became 0.5%.

<External additive addition process>
1 part by mass of hydrophobic silica (volume-based median diameter = 12 nm) and 0.3 part by mass of hydrophobic titania (volume-based median diameter = 20 nm) are added to 100 parts by mass of toner base particles 1, and the mixture is added using a Henschel mixer. By mixing, Toner 1 was produced.

(Confirmation of domain / matrix structure)
Using the toner 1 as a sample, the cross section of the toner base particles 1 dyed with ruthenium tetroxide was observed for the lamellar crystal structure as described below. As a result, the crystalline polyester resin lamellar was found in the amorphous resin matrix. A domain containing a crystal structure was confirmed.

(Lamella crystal structure observation method)
After staining as described below, the sample was observed with an electron microscope “JSM-7401F” (manufactured by JEOL Ltd.) within 24 hours.

-Conditions for equipment and samples-
・ Device: Electron microscope “JSM-7401F” (manufactured by JEOL Ltd.)
Sample: section of toner particles stained with ruthenium tetroxide (RuO4) (section thickness: 60 to 100 nm)
・ Acceleration voltage: 30 kV
-Magnification: 50000 times-Observation conditions: Transmission electron detector, bright field image

-Section preparation method of dyed toner particles-
1 to 2 mg of a sample (toner) is put in a 10 mL sample bottle, and after treatment under ruthenium tetroxide (RuO4) vapor staining conditions as shown in the following “ruthenium tetroxide treatment conditions”, a photocurable resin “D- 800 "(manufactured by JEOL Ltd.) and photocured to form a block. Next, an ultrathin sample having a thickness of 60 to 100 nm was cut out from the above block using a microtome equipped with diamond teeth.
Thereafter, the cut sample was again treated and dyed under the following ruthenium tetroxide treatment conditions.

-Ruthenium tetroxide treatment conditions-
The ruthenium tetroxide treatment is performed using a vacuum electron staining device VSC1R1 (manufactured by Philgen Co., Ltd.). In accordance with the procedure of the apparatus, a dye sublimation chamber containing ruthenium tetroxide is installed in the main body of the dyeing apparatus. After introducing a toner or ultrathin section into the staining chamber, the conditions for staining with ruthenium tetroxide are room temperature (24-25 ° C.), concentration. 3 (300 Pa) for 10 minutes.

(Preparation of toners 2 to 6 and 8)
In the production of the toner 1, except that the crystalline polyester resin fine particle dispersion liquid containing crystalline polyester resins (CPEs) shown in Table III (simply referred to as “fine particle dispersion liquid” in Table III) was changed to 1-6. In the same manner as in the production method of the toner 1, toners 2 to 6 were obtained.
For toner 8, toner 1 was produced in the same manner as toner 1 except that the crystalline polyester resin fine particle dispersion was not used.

For the toners 2 to 6 and 8, the domain / matrix structure was confirmed in the same manner as for the toner 1. For the toners 2 to 6, the same domain / matrix structure was confirmed.
For toner 8, the domain / matrix structure was not confirmed.

(Preparation of Toner 7)
In the production of the toner 1, the same procedure as in the toner 1 was carried out except that the crystalline polyester resin fine particle dispersion used was changed to the crystalline polyester resin fine particle dispersion 7 to produce a dispersion of the toner base particles 7. However, the dispersion was charged into 5000 parts by mass of ion-exchanged water during cooling of the dispersion and quenched. As with the toner 1, the domain matrix structure was confirmed. As a result, no crystalline polyester domain was observed for the toner 7.

[Evaluation of Examples 1 to 17 and Comparative Examples 1 to 9]
<Manufacture of developer>
A developer was produced by adding and mixing the carrier so that the toner concentration was 6.50% by mass, and used for the following evaluation.
The combinations of toner and carrier were as shown in Table IV.

  A commercially available multifunction device “bizhub PRO C6501 (manufactured by Konica Minolta Co., Ltd.)” was remodeled so that it can be forward-developed, and a developer composed of a toner and a carrier that is a combination of the photoreceptors 1 to 13 and Table IV was added. It was used to evaluate the occurrence of scavenging and carrier adhesion.

<Evaluation of scavenging (confirmation of lead blank)>
An image chart in which a solid image having an image density of 1.2 to 1.3 is printed at the rear of a halftone image having a density of 0.5 with black toner on A4 quality fine paper (64 g / m ² ) is printed. The portion that is white at the boundary between the solid image and the halftone image is regarded as a white portion, and the degree of scavenging at the boundary between the solid image and the halftone image is confirmed visually. Evaluated.

◎◎: No white spots in the lead part (pass)
A: There is almost no white spot in the lead (pass)
○: There is slight white spot in the lead, but it is not conspicuous (pass)
Δ: There is a white spot in the lead, but somehow within the practical range (pass)
×: The lead portion is clearly white and has a practical problem (failed)

<Carrier adhesion>
Carrier adhesion is achieved by printing a solid image (100 mm x 100 mm) after printing 200,000 character images with a printing rate of 5% in a printing environment of normal temperature and humidity (20 ° C, 50% RH). The number of carrier particles adhering to the film was visually evaluated using a magnifying glass. In addition, carrier adhesion makes 40 or less pass.

[Summary]
From Table IV, it was found that according to the electrophotographic image forming apparatus of the present invention, it is possible to suitably suppress the occurrence of lead white spots and carrier adhesion due to the scavenging phenomenon.

A Paper feed direction G1 Solid image G2 Halftone image W Near boundary with solid image S, S 'Developing sleeve P, P' Photoconductor W1, W1 ', W2, W2' Rotation direction

Claims (7)

An electrostatic latent image carrier having at least a photosensitive layer and a surface protective layer on a conductive support; a developing means using a charging means, an exposure means, a developer containing toner and a carrier; a transfer means; a fixing means; a cleaning means; An electrophotographic image forming apparatus comprising:
(1) The surface protective layer contains N-type semiconductor particles,
The N-type semiconductor particles have a volume resistivity in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁷ Ω · cm, and an average particle size in the range of 50 to 300 nm,
(2) the toner contains toner base particles having a domain matrix structure;
The domain contains a crystalline polyester resin and the matrix contains an amorphous resin;
(3) The electrophotographic image forming apparatus, wherein the resistance of the carrier is in a range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹¹ Ω · cm. 2. The electrophotographic image forming apparatus according to claim 1, wherein the resistance of the carrier is in the range of 1.0 × 10 ^{9 to} 5.0 × 10 ¹⁰ Ω · cm.   The electrophotographic image forming apparatus according to claim 1, wherein the N-type semiconductor particles contain any one of tin oxide, titanium oxide, zinc oxide, and indium tin oxide.   4. The electrophotographic image forming apparatus according to claim 1, wherein the amorphous resin contained in the matrix contains a styrene / acrylic resin. 5. The crystalline polyester resin contained in the domain is
When the carbon number of the main chain of the structural unit derived from the polyhydric alcohol is _Calcohol and the carbon number of the main chain of the structural unit derived from the polyvalent carboxylic acid is C _acid , the following relational expressions (1) and (2 The electrophotographic image forming apparatus according to any one of claims 1 to 4, wherein:
5 ≦ | C _acid −C _alcohol ≦≦ 12 (1)
_Calcohol <C _acid ... relational expression (2)   The crystalline polyester resin contained in the domain is a hybrid crystalline polyester resin obtained by chemically bonding a styrene / acrylic polymer segment to a polyester polymer segment. The electrophotographic image forming apparatus according to any one of the above.   The electrophotographic image forming apparatus according to any one of claims 1 to 6, wherein the developing unit is a unit that performs development by a normal development method.