JP2009036908A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus in which photoreceptors are less likely to be worn away and can maintain such stable characteristics as to cause no image defect even when they are different in wear amount according to use frequency, and in which the photoreceptors for different colors can be used for the same period of time and are low in cost, even in the case of a tandem system color image forming apparatus using organic photoreceptors excellent in photosensitivity characteristics, charging characteristics and characteristic stability in repeated use, and further having high mechanical durability, small dependence on film thickness loss and excellent ozone and NOx resistances. <P>SOLUTION: The image forming apparatus includes organic photoreceptors each obtained by stacking: a single-layer photosensitive layer containing a charge generating material and a charge transport material; or a multilayer photosensitive layer formed by stacking a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material in this order, on a conductive support comprising a conductive material. The single-layer photosensitive layer or the multilayer photosensitive layer contains a specific charge transport material and a specific diamine compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a color printer such as a color printer in which a plurality of electrophotographic photosensitive members (hereinafter also referred to as “photosensitive members”) called a tandem system are charged and a developing unit for storing a plurality of different color toners is disposed. The present invention relates to an image forming apparatus.

  In recent color electrophotographic processes, a tandem type color image forming apparatus that obtains a color image by arranging a plurality of photosensitive drums corresponding to toner colors in order to increase the printing speed has come to be used. Yes. Such a tandem method is a color image forming apparatus or multi-color image forming apparatus that sequentially stacks and transfers a plurality of component color images of color image information and multicolor image information, and outputs an image formed product in which a color image and a multicolor image are synthesized and reproduced. It is useful for a color image forming apparatus, or a color image forming apparatus or an image forming apparatus having a multicolor image forming function.

In color image forming apparatuses, not only color printing but also monochrome (black) printing is frequently performed. The operation control executed according to the user's mode designation is different.
First, when the color image output mode is designated, the positions of the yellow (Y), magenta (M), and cyan (C) photoconductors and the black photoconductor are set as normal positions in contact with the transfer conveyance belt. Each photoconductor is driven to rotate, and a charging / developing operation corresponding to each photoconductor is executed according to an electrophotographic process, whereby a color image is formed on a recording material (transfer paper).

  On the other hand, when the monochrome image output mode is designated, the contact / separation mechanism is driven to separate the yellow (Y), magenta (M), and cyan (C) photoconductors from the transfer conveyance belt. The rotation drive of each of the photoconductors is turned off to be in a stopped state. At the same time, the charging / developing operation for each of these photoconductors is also turned off. In this state, the black photoconductor is driven to rotate, and the black photoconductor is charged and developed in accordance with the electrophotographic process. A black and white image is formed.

As described above, when the black and white image output mode is designated, the photosensitive member other than the black photosensitive member is inactivated such as stopping its rotation operation and is separated from the transfer conveyance belt. Photoconductors other than the above photoconductors are prevented from being scraped by a cleaning blade or the like, or by being scraped by transfer paper or a transfer conveyance belt.
However, there are cases where monochrome printing is used more frequently than color printing, and the black photoconductor has the disadvantage of relatively faster wear than other color photoconductors.

Usually, the wear characteristics of the four photoconductors are different for each of the four colors of yellow (Y), magenta (M), cyan (C), and black, and the photoconductor is deteriorated depending on the color of the toner. If the photoconductor is worn and deteriorated unevenly for each toner, color unevenness of color image quality occurs with the number of copies.
However, the wear deterioration speed of the photosensitive drum varies depending on the type of the developing machine for each color, and even if only one of them deteriorates, if all the drums are not replaced, the replaced drums and the drums that have not been replaced The color balance between them is out of order, and good image quality cannot be obtained. In other words, the interval until the drum replacement is limited by the drum corresponding to the most severely deteriorated color among the four drums, that is, the black drum, and becomes unnecessarily large.

As countermeasures for the above, Japanese Patent Application Laid-Open No. 10-333393 (Patent Document 1), Japanese Patent Application Laid-Open No. 11-24358 (Patent Document 2) and Japanese Patent Application Laid-Open No. 11-52599 (Patent Document 3) include It has been proposed that an α-Si or α-SiC photoconductor is used only for the photoconductor to extend the lifetime, and that OPC (organic photoconductor) is used for photoconductors for other colors except black.
However, the α-Si or α-SiC photoconductor has a problem of low chargeability.
As a method for solving this drawback, Patent Document 1 proposes that the thickness of the photoconductor is 30 μm or more and the charging difference from the organic photoconductor is 200 V or less.
Patent Document 2 proposes that the voltage applied to the α-Si photoconductor is 1.05 to 2.50 times that of the organic photoconductor.
Further, in Patent Document 3, the charging property is increased by providing an α-SiC surface layer.

Thus, in order to use a black photoconductor for a long time and to compensate for the low charging property of the α-Si or α-SiC photoconductor, it is necessary to control complicated charging only for black, and as a result Cost is required.
In addition to charging, the α-Si or α-SiC photoconductor and the organic photoconductor are different in the sensitivity to light and the influence of temperature / humidity, so the black α-Si or α-SiC photoconductor and the black photoconductor are black. For organic photoreceptors used for other purposes, the exposure amount, transfer conditions, etc. are different, and for black photoreceptors and non-black photoreceptors, different control methods must be employed. Cost becomes necessary.

  Further, the α-Si or α-SiC photoconductor described in Patent Document 1, Patent Document 2 and Patent Document 3 has a problem that the production cost is clearly higher than that of the organic photoconductor. Needless to say, there is another problem that the toner for black is consumed much.

As countermeasures for the above, JP 2000-242056 (Patent Document 4) and JP 2000-242057 (Patent Document 5) disclose that the drum diameter is increased only for the black photosensitive member, or the film thickness is increased. It has been proposed to make it thicker.
Japanese Patent Application Laid-Open No. 2001-51467 (Patent Document 6) describes that only a black photoreceptor uses a non-contact charging means, uses a resin with a large viscosity average molecular weight, a thick film thickness. ing.
Furthermore, Japanese Patent Application Laid-Open No. 2000-330303 (Patent Document 7) describes using a copolymer polycarbonate resin as a resin for a tandem photoreceptor.

Furthermore, the amount of ozone and NOx generated by the image forming apparatus is large, and the photoconductor is liable to be deteriorated as the space is saved. In addition, it is difficult to provide an exhaust device for them in terms of space, which is not preferable from the viewpoint of cost increase.
In order to use a photoconductor for the same period for each color, a photoconductor that is not easily worn, that is, a photoconductor having a surface layer with high printing durability and strong ozone resistance and NOx is desired.

JP 10-333393 A Japanese Patent Laid-Open No. 11-24358 Japanese Patent Laid-Open No. 11-52599 JP 2000-242056 A JP 2000-242057 A JP 2001-51467 A JP 2000-330303 A

The present invention is a tandem using an organic photoconductor that has excellent photosensitivity characteristics, charging characteristics, stability in repeated use, high mechanical durability, low film thickness dependence, and excellent ozone resistance and NOx resistance. Even in a color image forming apparatus of the type, the photoconductor is not easily worn, and stable characteristics without image defects can be maintained even if the wear amount of each photoconductor varies depending on the frequency of use. It is an object of the present invention to provide a color image forming apparatus that is capable of reducing the cost.
The organic photoreceptor means an electrophotographic photoreceptor provided with a photosensitive layer containing an organic photoconductive material as a main component, and is also referred to as “photoreceptor” below.

Thus, according to the present invention, the organic photoreceptor, the charging means for charging the organic photoreceptor, the exposure means for exposing the charged organic photoreceptor, and the electrostatic latent image formed by the exposure. Developing means for developing the toner image to form a toner image, transfer means for transferring the developed toner image onto the recording material, and fixing means for fixing the transferred toner image on the recording material to form an image And a plurality of image forming units provided with at least cleaning means for removing and collecting the toner remaining on the organic photoreceptor, and different color toners using different color toners for each of the plurality of image forming units. An image forming apparatus that sequentially superimposes an image on a recording material to form a color image;
The organic photoreceptor comprises a single layer type photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support made of a conductive material, or a charge generating layer containing a charge generating substance and a charge transporting substance. A layered photosensitive layer in which the charge transporting layer is stacked in this order is laminated, and the charge transporting layer of the single layered photosensitive layer or the layered photosensitive layer is used as a charge transporting substance,
General formula (1):

[Where:
Ar ¹ and Ar ² are the same or different and are an aryl group which may have a substituent or a monovalent heterocyclic residue which may have a substituent, and Ar ¹ and Ar ² bind to them May be bonded to each other through a group of atoms or atomic groups to form a ring structure;
Ar ³ is an aryl group that may have a substituent, a cycloalkyl group that may have a substituent, an alkyl group that may have a substituent, or a monovalent complex that may have a substituent. A ring residue;
Ar ⁴ and Ar ⁵ are the same or different and each represents a hydrogen atom, an aryl group which may have a substituent, an alkyl group which may have a substituent, or a monovalent heterocyclic ring which may have a substituent A residue, Ar ⁴ and Ar ⁵ are not both hydrogen atoms, but may be bonded to each other via an atom or atomic group bonded to them to form a ring structure;
a represents an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a dialkylamino group which may have a substituent, an aryl group which may have a substituent, a halogen atom; Or a hydrogen atom;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a may be the same or different and are bonded to each other via an atom or an atomic group bonded thereto to form a ring structure. Well;
R ¹ is a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are the same or different and are a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or a monovalent which may have a substituent. A heterocyclic residue of
n is an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, and when n is 0, Ar ³ has a substituent. A monovalent heterocyclic residue)
An enamine compound represented by
Formula (I):

[Where:
Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ are the same or different, and may be an aryl group which may have a substituent, a cycloalkyl group which may have a substituent, or a hetero which may have a substituent. A monovalent heterocyclic residue optionally having an atom-containing cycloalkyl group or a substituent;
^{Y 1, Y 2, Y 3} , Y 4, Y 5 and Y ⁶ are the same or different, have a good chain alkylene group which may have a substituent;
Z is i) —Ar ¹⁰ —Ar ¹¹ — or ii) —Ar ¹⁰ —W—Ar ¹¹ — (wherein Ar ¹⁰ and Ar ¹¹ are the same or different and may have a substituent) Or a divalent heterocyclic residue which may have a substituent; W is a cycloalkylidene group which may have a substituent, or a chain or branched alkylene group which may have a substituent An oxygen atom or a sulfur atom)
And a diamine compound represented by the formula:

  According to the present invention, an organic photoreceptor having excellent photosensitivity characteristics, charging characteristics, characteristic stability in repeated use, high mechanical durability, small film thickness dependence, and excellent ozone resistance and NOx resistance is used. Even in the conventional tandem color image forming apparatus, the photoconductors are less likely to wear, and even if the wear amount of each photoconductor varies depending on the frequency of use, stable characteristics without image defects can be maintained. Thus, a color image forming apparatus can be provided at a low cost.

Since the photoreceptor of the image forming apparatus of the present invention contains an enamine compound represented by the general formula (1) having a high charge mobility as a charge transport material, the charged potential is high, the sensitivity is high, and the photoresponse is sufficient. Showing gender.
In addition, since the photoreceptor of the image forming apparatus of the present invention contains the diamine compound represented by the general formula (I), it is excellent in ozone resistance and NOx property, and when used in a low temperature environment or in a high speed process. These characteristics do not deteriorate, and those characteristics do not deteriorate even when exposed to light.
Furthermore, since the content of the binder resin in the charge transport layer can be increased, the wear amount of the photoreceptor is small.
Therefore, the image forming apparatus of the present invention can achieve high sensitivity and high durability.

  In addition, the photosensitive layer is a laminated photosensitive layer in which a charge generation function and a charge transport function are assigned to separate layers, that is, a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material in this order. By making the layered photosensitive layer laminated with, it is possible to select the most suitable material for each function, so that the photosensitivity has higher sensitivity and higher stability with repeated use. A body can be obtained, and an image forming apparatus using the body can achieve higher sensitivity and higher durability.

  Further, since the content of the binder resin in the single layer type photosensitive layer or the charge transport layer of the multilayer type photosensitive layer in the photosensitive member can be increased, a photosensitive member with a small amount of wear can be provided. That is, the photoconductor of the image forming apparatus of the present invention can maintain photoresponsiveness even when a binder resin is added at a higher ratio than when a known charge transport material is used. And the durability of the photoreceptor can be improved. Therefore, the image forming apparatus using the same maintains the stable characteristics with no image defect even in the case of the color image forming apparatus of the tandem type, even if the photoconductor is not easily worn and the wear amount of each photoconductor varies depending on the use frequency. A cost-effective color image forming apparatus can be provided.

  Further, by blending an appropriate amount of the diamine compound represented by the general formula (I) with respect to the charge transport material of the photosensitive layer, particularly high charge mobility can be maintained, the charging potential is high, the sensitivity is high, and sufficient light is obtained. Photoreceptor that shows responsiveness, has excellent durability, does not deteriorate even when used in low-temperature ring or high-speed processes, and is less dependent on film thickness reduction due to abrasion. Therefore, an image forming apparatus using the image forming apparatus can achieve higher sensitivity and higher durability.

  Further, the image forming apparatus of the present invention can provide a color image forming apparatus capable of high-speed printing by including an intermediate transfer member, and a conventional corona charging system by using a contact charging system as a charging unit. The amount of ozone and NOx can be reduced, and a high-speed and highly durable image forming apparatus can be provided.

An image forming apparatus according to the present invention includes an organic photoreceptor, a charging unit that charges the organic photoreceptor, an exposure unit that exposes the charged organic photoreceptor, and an electrostatic latent image formed by exposure. Developing means for developing the toner image to form a toner image, transfer means for transferring the developed toner image onto the recording material, and fixing means for fixing the transferred toner image on the recording material to form an image And a plurality of image forming units provided with at least cleaning means for removing and collecting the toner remaining on the organic photoreceptor, and different color toners using different color toners for each of the plurality of image forming units. An image forming apparatus that sequentially superimposes an image on a recording material to form a color image;
The organic photoreceptor comprises a single layer type photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support made of a conductive material, or a charge generating layer containing a charge generating substance and a charge transporting substance. A layered photosensitive layer in which the charge transporting layer is stacked in this order is laminated, and the single layer type photosensitive layer or the charge transporting layer of the layered type photosensitive layer has a general formula (1 ) And an diamine compound represented by the general formula (I).

Hereinafter, the image forming apparatus of the present invention will be described in detail with reference to the drawings. However, the image forming apparatus of the present invention is not limited to the contents described below.
FIG. 1 is a schematic cross-sectional view of a tandem type color multifunction peripheral equipped with a photoreceptor, showing an example of the image forming apparatus of the present invention. In the drawing, reference numerals 3a, 3b, 3c and 3d denote photoconductors (photoconductor drums). Details will be described later.
2 to 4 are schematic cross-sectional views showing the configuration of the main part of the photoreceptor in the image forming apparatus of the present invention.
FIGS. 2 and 3 show a laminated type photoreceptor (hereinafter “function-separated type photoreceptor”) in which the photosensitive layer is a laminated type photosensitive layer (hereinafter also referred to as “function-separated type photosensitive layer”) composed of a charge generation layer and a charge transport layer. It is a schematic cross section which shows the structure of the principal part. The photoreceptor of the present invention may have a reverse two-layered laminated structure in which a charge generating layer and a charge transporting layer are formed in reverse order, but the laminated type is preferred.
FIG. 4 is a schematic cross-sectional view showing the configuration of the main part of a single-layer type photoreceptor that is a single-layer type photosensitive layer having a single photosensitive layer.

The photoconductor of FIG. 2 is a laminated type photoconductor in which a charge generating layer 205 containing a charge generating material 202 and a charge transporting layer 206 containing a charge transporting material 203 are laminated on the surface of a conductive support 201 in this order. A layer 204 is formed.
3 has an undercoat layer (also referred to as an “intermediate layer”) 208, a charge generation layer 205 containing a charge generation material 202, and a charge containing a charge transport material 203 on the surface of a conductive support 201. A laminated photosensitive layer 204 in which the transport layer 206 is laminated in this order is formed in this order.
In the photoreceptor of FIG. 4, an undercoat layer 208 and a single-layer type photosensitive layer 204 ′ containing a charge generation material 202 and a charge transport material 203 are formed in this order on the surface of a conductive support 201. Yes.

  The charge transport layer of the single-layer type photosensitive layer or the multilayer type photosensitive layer provided in the image forming apparatus of the present invention includes an enamine compound represented by the general formula (1) and a general formula (I) as a charge transport material. And a diamine compound represented by the formula:

[Enamine compounds]
The enamine compound represented by the general formula (1) as a charge transport material has an ability to accept and transport charges generated by the charge generation material.
Among the enamine compounds represented by the general formula (1), the sub-formula (2):

[Where:
b, c and d are the same or different and each has an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a dialkylamino group which may have a substituent, or a substituent. An aryl group, a halogen atom or a hydrogen atom, which may be
i, j and k are the same or different and are integers of 1 to 5, and when i, k or j is 2 or more, the corresponding plural b, c or d may be the same or different, and May be bonded to each other via an atom or atomic group bonded to the ring to form a ring structure;
Ar ⁴ , Ar ⁵ , a and m have the same meaning as in general formula (1)]
The enamine compound represented by is particularly preferable.

The substituents in general formula (I) and sub-formula (2) will be described.
Examples of the aryl group that may have a substituent of Ar ¹ and Ar ² include, for example, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a dialkylamino group having 2 to 6 carbon atoms, and a halogen atom. And an aryl group which may be substituted with.
Specific examples include a phenyl group, a p-tolyl group, a 4-methoxyphenyl group, a 4-chlorophenyl group, a 4-fluorophenyl group, a 1-naphthyl group, and a 2-naphthyl group.
Examples of the monovalent heterocyclic residue which may have a substituent for Ar ¹ and Ar ² include a monovalent heterocyclic residue which may be substituted with an alkyl group having 1 to 4 carbon atoms. .
Specific examples include a benzothiazolyl group and a thienyl group.

Examples of the aryl group which may have a substituent of Ar ³ include the same aryl groups as those which may have a substituent of Ar ¹ and Ar ² .
Specifically, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 4-isopropylphenyl group, 3,4-dimethylphenyl group, 2-fluorophenyl group, 4-methoxyphenyl group, 2 , 4-dimethoxyphenyl group, 2-methyl-4-methoxyphenyl group, 2,5-dimethyl-4-methoxyphenyl group, 4-biphenylyl group, p-terphenyl group, 4-dimethylaminophenyl group, 4-triphenyl Fluoromethylphenyl group, 1-naphthyl group, 2-naphthyl group, 2-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5-methyl-1-naphthyl group, 4-methoxy-1-naphthyl group 2-methyl-4-methoxy-1-naphthyl group, 4- (4-methyl-phenoxy) phenyl group, 4- (phenylthio) phenyl group, 2,5-dimethyl-4- Phenylthio) phenyl group.

Examples of the cycloalkyl group which may have a substituent for Ar ³ include a cycloalkyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms.
Specific examples include a cyclohexyl group, a cyclopentyl group, and a 4,4-dimethylcyclohexyl group.
Examples of the alkyl group that may have a substituent for Ar ³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 2-thienylmethyl group, and a 1-naphthylmethyl group. Is mentioned.
Examples of the monovalent heterocyclic residue optionally having an Ar ³ substituent include a furyl group, a thienyl group, a 5-methyl-2-furyl group, a 5-methyl-2-thienyl group, and a 5-methyl-N group. -Ethylcarbazol-4-yl group.

Examples of the aryl group which may have a substituent for Ar ⁴ and Ar ⁵ include the same aryl groups as those which may have a substituent for Ar ³ .
Specifically, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 4-isopropylphenyl group, 3,4-dimethylphenyl group, 2-fluorophenyl group, 4-chlorophenyl group, 4- (2-fluoroethyl) phenyl group, 4-methoxyphenyl group, 2,4-dimethoxyphenyl group, 2-methyl-4-methoxyphenyl group, 2,5-dimethyl-4-methoxyphenyl group, 4-biphenylyl group, p-terphenyl group, 4-dimethylaminophenyl group, 4-trifluoromethylphenyl group, 1-naphthyl group, 2-naphthyl group, 2-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5 -Methyl-1-naphthyl group, 4-methoxy-1-naphthyl group, 6-methoxy-2-naphthyl group, 2-methyl-4-methoxy-1-naphthyl group, 9-a Tolyl, 1-pyrenyl, 4- (4-methyl-phenoxy) phenyl, 4- (phenylthio) phenyl, 2,5-dimethyl-4- (phenylthio) phenyl, p- (phenylthio) phenyl and Examples thereof include a p-styrylphenyl group.

Examples of the alkyl group which may have a substituent of Ar ⁴ and Ar ⁵ include, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, and a fluoromethyl group. And 1-methoxyethyl group.
Examples of the monovalent heterocyclic residue that may have a substituent for Ar ⁴ and Ar ⁵ include the same alkyl groups that may have a substituent for Ar ³ .
Specifically, 8-chromanyl group, furyl group, thienyl group, 5-methyl-2-furyl group, 5-methyl-2-thienyl group, 5-methyl-N-ethylcarbazol-4-yl group, thiazolyl group Benzofuryl group, benzothiophenyl group, N-methylindolyl group, benzothiazolyl group, benzoxazolyl group and the like.

Ar ⁴ and Ar ⁵ may be bonded to each other via an atom or an atomic group to form a ring structure. Specific examples of the bonding atom include an oxygen atom and a sulfur atom. Specific examples of the bonding atom group include a divalent atomic group such as a nitrogen atom having an alkyl group, and methylene, ethylene, methylmethylene, and the like. Alkylene groups, unsaturated alkylene groups such as vinylene and propenylene, alkylene groups containing heteroatoms such as oxymethylene (chemical formula: —O—CH ₂ —), heterogeneous such as thiovinylene (chemical formula: —S—CH═CH—) And divalent groups such as an unsaturated alkylene group containing an atom.

Examples of the alkyl group which may have a substituent of a include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, a fluoromethyl group, and 1-methoxy. An ethyl group etc. are mentioned.
Examples of the alkoxy group which may have a substituent include a methoxy group, ethoxy group, n-propoxy group and isopropoxy group.
Examples of the dialkylamino group which may have a substituent a include a dimethylamino group, a diethylamino group, and a diisopropylamino group.
Examples of the aryl group that may have a substituent include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 4-methoxyphenyl group, and the like.
Examples of the halogen atom for a include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the halogen atom for R ¹ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group which may have a substituent for R ¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, a fluoromethyl group, and 1- A methoxyethyl group etc. are mentioned.

Examples of the alkyl group which may have a substituent of R ² , R ³ and R ⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, Examples thereof include a fluoromethyl group and a 1-methoxyethyl group.
Examples of the aryl group which may have a substituent for R ² , R ³ and R ⁴ include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, and a 4-methoxyphenyl group. .
Examples of the monovalent heterocyclic residue which may have a substituent for R ² , R ³ and R ⁴ include the same as those for Ar ¹ , Ar ² and Ar ³ .

Examples of the alkyl group which may have a substituent of b, c and d include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, and a fluoromethyl group. And 1-methoxyethyl group.
Examples of the alkoxy group which may have a substituent for b, c and d include a methoxy group, an ethoxy group, an n-propoxy group and an isopropoxy group.
Examples of the dialkylamino group which may have a substituent for b, c and d include a dimethylamino group, a diethylamino group and a diisopropylamino group.
Examples of the aryl group which may have a substituent for b, c and d include the same groups as those for Ar ¹ , Ar ² and Ar ³ .
Examples of the halogen atom for b, c and d include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Among the enamine compounds represented by the general formula (1), Ar ¹ and Ar ² are phenyl groups, and Ar ³ is a phenyl group and a tolyl group, particularly excellent from the viewpoints of characteristics, cost, and productivity. P-methoxyphenyl group, biphenylyl group, naphthyl group or thienyl group, and at least one of Ar ⁴ and Ar ⁵ is phenyl group, p-tolyl group, p-methoxyphenyl group, naphthyl group, thienyl group Or it is a thiazolyl group, R ¹ , R ² , R ³ and R ⁴ are all hydrogen atoms and n is 1.

Specific examples of the enamine compound of the present invention are shown in Tables 1-1 to 1-32, but the present invention is not limited by these exemplified compounds.
The enamine compound of the present invention can be synthesized by the method described in JP-A No. 2004-151666.
Each group shown in Table 1 corresponds to each group of general formula (1). However, in the case where Ar ⁴ and Ar ⁵ are combined to form a ring structure is a column of Ar ⁴ and Ar ^5, carbon Ar ⁴ and Ar ⁵ are attached - carbon double bond, the carbon - carbon double The ring structure formed by Ar ⁴ and Ar ⁵ together with the carbon atoms of the heavy bond is shown together. For example, Exemplified Compound Nos. 1 is an enamine compound represented by the following structural formula (1-1).

[Diamine compound]
The diamine compound represented by the general formula (I) imparts excellent ozone resistance and NOx property to the photoreceptor. Among these diamine compounds, when considering chemical stability such as decomposition or alteration as a chemical substance, availability of raw materials, ease of production and high yield, and production cost, sub-formula (II):

（式中、Ａｒ⁶、Ａｒ⁷、Ａｒ⁸、Ａｒ⁹、Ａｒ¹⁰およびＡｒ¹¹は、一般式（１）と同義である）
で示されるジアミン化合物が好ましく、構造式（III）：

(In the formula, Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ and Ar ¹¹ have the same meanings as in the general formula (1)).
A diamine compound represented by the formula (III):

で示されるジアミン化合物が特に好ましい。

A diamine compound represented by is particularly preferred.

The substituents in the general formula (1), sub formula (2) and sub formula (3) will be described.
Examples of the aryl group which may have a substituent of Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ include, for example, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkyl group having 2 to 6 carbon atoms. Examples include a dialkylamino group and an aryl group which may be substituted with a halogen atom.
Specifically, phenyl group, o-tolyl group, 2,4-xylyl group, 4-methoxyphenyl group, 3-methoxy-4-methylphenyl group, t-butylphenyl group, 4-diethylaminophenyl group, 4- A chlorophenyl group, a 4-fluorophenyl group, a 1-naphthyl group, a 2-naphthyl group, etc. are mentioned. Among these, a phenyl group, an o-tolyl group, a 4-methoxyphenyl group, a 1-naphthyl group, a 2-naphthyl group Is particularly preferred.

Examples of the cycloalkyl group which may have a substituent for Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ include a cycloalkyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms.
Specific examples include a cyclohexyl group, a cyclopentyl group, a 4,4-dimethylcyclohexyl group, and among these, a cyclohexyl group is particularly preferable.

Examples of the hetero atom-containing cycloalkyl group which may have a substituent of Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ include a tetrahydrofuryl group and a tetramethyltetrahydrofuryl group.

As the monovalent heterocyclic residue which may have a substituent of Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ , for example, a monovalent complex which may be substituted with an alkyl group having 1 to 4 carbon atoms. A ring residue is mentioned.
Specific examples include a furyl group, a 4-methylfuryl group, a benzofuryl group, and a benzothiophenyl group. Among these, a furyl group and a benzofuryl group are particularly preferable.

The chain alkylene group which may have a substituent of Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ and Y ⁶ may be substituted with, for example, an alkyl group having 1 to 4 carbon atoms. An alkylene group is mentioned.
Specific examples include a methylene group, an ethylene group, a propylene group, and a 2,2-dimethylpropylene group. Among these, a methylene group and an ethylene group are particularly preferable.

Examples of the arylene group which may have a substituent of Ar ¹⁰ and Ar ¹¹ in Z include an arylene group which may be substituted with an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. It is done.
Specific examples include p-phenylene group, m-phenylene group, methyl-p-phenylene group, methoxy-p-phenylene group, 1,4-naphthylene group, benzoxazolen group, biphenylylene group, and the like. Among them, p-phenylene group, m-phenylene group, methyl-p-phenylene group, methoxy-p-phenylene group and 1,4-naphthylene group are preferable, and p-phenylene group and 1,4-naphthylene group are particularly preferable. .

Examples of the divalent heterocyclic residue optionally having a substituent for Ar ¹⁰ and Ar ¹¹ in Z include a 1,4-furandiyl group, a 1,4-thiophenediyl group, and a 2,5-benzofurandyl group. 2,5-benzoxazolediyl group and N-ethylcarbazole-3,6-diyl group.

Examples of the cycloalkylidene group which may have a substituent of W in Z include a cycloalkylidene group which may be substituted with an alkyl group having 1 to 4 carbon atoms.
Specific examples include a cyclopentylidene group, a cyclohexylidene group, and a 4,4-dimethylcyclohexylidenyl group.

Examples of the chain or branched alkylene group which may have a substituent include an alkylene group which may be substituted with an alkyl group having 1 to 4 carbon atoms.
Specific examples include a methylene group, an ethylene group, a trimethylene group, and a 2,2-dimethyltrimethylene group. Among these, a methylene group and an ethylene group are particularly preferable.

Specific examples of the diamine compound of the present invention are shown in Tables 2-1 to 2-4, but the present invention is not limited to these exemplified compounds.
In Tables 1-1 to 1-4, the substituents are represented by the following abbreviations.
-Me-: methylene group -Et-: ethylene group -Tr-: trimethylene group -Dm-: 2,2-dimethyltrimethylene group

  The diamine compound of the present invention can be produced by the method shown in the following reaction scheme. That is, by heating the amine compound represented by the general formula (IV) and the general formula (V) and the dihalogen compound represented by the general formula (VI) in the presence of an organic amine base, the yield can be easily increased. The target product can be produced with high purity.

[Reaction formula]

(Wherein Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ , Y ⁹ and Z are as defined in formula (I); X ¹ and X ² represents a halogen atom)
Examples of the halogen atom of X ¹ and X ² in the reaction formula include a chlorine atom, a bromine atom, and an iodine atom, and among these, a chlorine atom and a bromine atom are particularly preferable.

The reaction of the above reaction formula can be carried out, for example, as follows.
The secondary amine compounds (IV) and (V) and the dihalogen compound (VI) are dissolved or dispersed in a solvent, an organic amine base is added thereto, and the mixture is heated and stirred. After completion of the reaction, the precipitate is filtered off and recrystallized in ethanol, methanol, ethyl acetate or the like alone or in a mixed solvent system, whereby the target product can be obtained easily and with high purity in high yield.

The solvent is not particularly limited as long as it is inert to the above reaction and can dissolve or disperse the reaction substrate and the organic amine base. Specifically, aromatic hydrocarbons such as toluene and xylene; ethers such as diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and 1,4-dioxane; amides such as N, N-dimethylformamide; dimethyl sulfoxide and the like Examples thereof include sulfoxides, and these can be used alone or as a mixed solvent.
The amount of the solvent used is not particularly limited, and the amount by which the reaction smoothly proceeds may be appropriately set according to the reaction conditions such as the amount of the reaction substrate used, the reaction temperature, and the reaction time.
Examples of the organic amine base include N, N-diisopropylethylamine, N, N-dimethylaminopyridine, 1,4-diazabicycloundecene and the like.

The ratio of the secondary amine compounds (IV) and (V) to the dihalogen compound (VI) is not particularly limited.
For example, when obtaining a symmetrical compound (when either one of the secondary amine compounds (IV) and (V) is used), 1 equivalent of the dihalogen compound (VI) is taken into consideration in view of the efficiency of the reaction. The secondary amine compound is preferably used in an amount of about 2.0 to 2.3 equivalents.
In addition, when obtaining an asymmetric compound (when using both secondary amine compounds (IV) and (V)), the reaction efficiency and the like are taken into consideration with respect to 1 equivalent of the dihalogen compound (VI). Each secondary amine compound is preferably used in an amount of about 1.0 to 1.2 equivalents (the total of the secondary amine compounds (IV) and (V) is about 2.0 to 2.4 equivalents).

The use ratio of the dihalogen compound (VI) and the organic amine base is not particularly limited, but considering the efficiency of the reaction, the organic amine base is used in an amount of 2. with respect to 1 equivalent of the dihalogen compound (VI). It is preferable to use about 05 to 5.0 equivalents.
Moreover, although heating temperature and reaction time are not specifically limited, Considering reaction efficiency etc., it is preferable to make it react at 60-120 degreeC for 2 to 8 hours, although it is based also on the solvent to be used.

  Next, each layer constituting the photoreceptor will be described.

[Conductive support 201]
The constituent material of the conductive support is not particularly limited as long as it is a material used in this field.
Specifically, metallic materials such as aluminum, aluminum alloys, copper, zinc, stainless steel, titanium: substrate surface made of polymer materials such as polyethylene terephthalate, polyamide, polyester, polyoxymethylene, polystyrene, hard paper, glass, etc. And metal foil laminated, metal material deposited, conductive polymer, tin oxide, indium oxide or other conductive compound layer deposited or applied.

The shape of the conductive support is not limited to a sheet shape as shown in FIGS. 1 to 8, and may be a cylindrical shape, a columnar shape, an endless belt shape, or the like.
If necessary, the surface of the conductive support 1 is irregularly reflected within a range that does not affect the image quality, such as anodized film treatment, surface treatment with chemicals, hot water, coloring treatment, or roughening the surface. It may be processed.

  The irregular reflection treatment is particularly effective when the photoreceptor according to the present invention is used in an electrophotographic process using a laser as an exposure light source. That is, in the electrophotographic process using a laser as an exposure light source, the wavelength of the laser beam is uniform, so the laser beam reflected on the surface of the photoconductor and the laser beam reflected inside the photoconductor cause interference, Interference fringes due to this interference may appear in the image and cause image defects. Therefore, by performing irregular reflection processing on the surface of the conductive support, it is possible to prevent image defects due to interference of laser light having a uniform wavelength.

[Single-layer type photosensitive layer 204 ′]
The single-layer type photosensitive layer contains at least a charge generating material, an enamine compound represented by the general formula (1) as a charge transport material, a diamine compound represented by the general formula (I), and a binder resin.

The charge generation material has an ability to generate charges by absorbing light.
As the charge generation material, a compound used in this field can be used.
Specifically, azo pigments (monoazo pigments, bisazo pigments, trisazo pigments, etc.), indigo pigments (indigo, thioindigo, etc.), perylene pigments (perylene imide, perylene acid anhydride, etc.), polycyclic quinone pigments Pigments (anthraquinone, pyrenequinone, etc.), phthalocyanine pigments (metal phthalocyanine, X-type metal-free phthalocyanine, etc.), organic pigments or dyes such as squarylium dyes, pyrylium salts, thiopyrylium salts, triphenylmethane dyes, selenium, amorphous Examples thereof include inorganic materials such as silicon. These charge generating materials can be used alone or in combination of two or more.

Among these charge generation materials, phthalocyanine pigments such as metal phthalocyanine and X-type metal-free phthalocyanine are preferable, and oxotitanium phthalocyanine is particularly preferable.
Since phthalocyanine pigments have high charge generation efficiency and charge injection efficiency, they generate a large amount of charge by absorbing light, and in the single layer type photosensitive layer without accumulating the generated charge in the molecule. Since charges are efficiently injected into the contained charge transport material and smoothly transported, a highly sensitive and high resolution photoreceptor can be obtained. This effect is the same for the laminated type photoconductor described later.

Charge generating materials can be used in combination with sensitizing dyes.
Examples of such sensitizing dyes include triphenylmethane dyes typified by methyl violet, crystal violet, knight blue and victoria blue; acridines typified by erythrosine, rhodamine B, rhodamine 3R, acridine orange and frappeosin. Dyes; thiazine dyes typified by methylene blue and methylene green; oxazine dyes typified by capri blue and meldra blue; cyanine dyes; styryl dyes; pyrylium salt dyes and thiopyrylium salt dyes.

As the charge transport material, the enamine compound represented by the general formula (1) is used, but other charge transport materials may be used in combination as long as the effects of the present invention are not impaired.
Other charge transport materials include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, many Ring aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives And benzidine derivatives, polymers having groups derived from these compounds in the main chain or side chain (poly-N-vinyl Carbazole, poly-1-vinylpyrene and poly-9-vinyl anthracene) and the like.
However, in order to achieve a particularly high charge transport capability, the total amount of the charge transport material is preferably an enamine compound represented by the general formula (1).

  As the binder resin, for example, a resin having a binding property used in this field can be used for the purpose of improving the mechanical strength, durability, etc. of the single-layer type photosensitive layer, and the diamine compound of the present invention can be used. Those having excellent compatibility are preferred.

  Specifically, vinyl resins such as polymethyl methacrylate, polystyrene, polyvinyl chloride, polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, polyphenylene oxide, etc. Thermoplastic resin: Thermosetting resin such as phenoxy resin, epoxy resin, silicone resin, polyurethane, phenol resin, alkyd resin, melamine resin, phenoxy resin, polyvinyl butyral, polyvinyl formal, partially cross-linked products of these resins, these resins Copolymer resins containing two or more of the structural units contained in (vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, acrylo Tolyl - insulating resin such as styrene copolymer resin). These binder resins can be used alone or in combination of two or more.

Among these resins, polystyrene, polycarbonate, polyarylate, and polyphenylene oxide are particularly excellent in compatibility with the diamine compound of the present invention, and further have a volume resistance of 10 ¹³ Ω or more, excellent electrical insulation, and composition. Polycarbonate is particularly preferred because it is excellent in film properties, potential characteristics, and the like.

The ratio T / R between the weight T of the charge transport material and the weight R of the binder resin is preferably 10/12 to 10/30, particularly preferably 10/16 to 10/24.
When the ratio T / R is less than 10/30 and the binder resin ratio is high, the mechanical strength is good, but the viscosity of the coating solution increases when a single-layer type photosensitive layer is formed by the dip coating method. As a result, the coating speed is lowered, and the productivity may be remarkably deteriorated. Further, if the amount of the solvent in the coating solution is increased in order to suppress an increase in the viscosity of the coating solution, a brushing phenomenon may occur and white turbidity may occur in the formed charge transport layer.

On the other hand, if the ratio T / R exceeds 10/12 and the binder resin ratio is low, the sensitivity characteristics are good, but the charging characteristics, the mechanical strength of the film, the image stability against ozone generated in the charging process, NOx, etc. Characteristics (half-tone white spots, black belts) are lowered, printing durability is lowered as compared with a high binder resin ratio, and the wear amount of the photosensitive layer may be increased.
Thus, even when a binder resin is added at a higher ratio than when a conventionally known charge transport material is used, the photoresponsiveness can be maintained. Therefore, the printing durability of the charge transport layer can be improved and the durability of the electrophotographic photosensitive member can be improved without reducing the photoresponsiveness.

The content of the diamine compound of the general formula (I) is 0.5% by weight or more with respect to the charge transport material.
It is preferably 0% by weight or less, particularly preferably 1.0% by weight or more and 5.0% by weight or less.
When the content of the diamine compound is less than 0.5% by weight, image stability (half-tone blanking and black band generation) against ozone, NOx, etc. generated in the charging process may be lowered. On the other hand, when the content of the diamine compound exceeds 10% by weight, the photoresponsiveness may decrease.

In addition, the single-layer type photosensitive layer contains known additives such as antioxidants, leveling agents, plasticizers, and ultraviolet absorbers used in this field as long as the effects of the present invention are not impaired. Also good. Such an additive is preferable because the stability as a coating solution for forming a photosensitive layer is increased and the life of the solution is extended, and the photoreceptor produced with the coating solution is also reduced in oxidizing impurities and improved in durability.
Examples of the antioxidant include vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkane and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds.
Examples of the leveling agent include silicone oils, polymers or oligomers having a perfluoroalkyl group in the side chain.

  Although the usage-amount of a well-known additive is not specifically limited, 0.1-1 weight part is preferable with respect to 100 weight part of binder resin. When the amount of the additive used is less than 0.1 part by weight, the effect of improving the stability of the coating solution for forming a photosensitive layer and the durability of the photoreceptor, which will be described later, may be insufficient, and the amount exceeds 1 part by weight. May adversely affect the electrical characteristics of the photoreceptor.

The charge generation material, the enamine compound represented by the general formula (1) as the charge transport material, the diamine represented by the general formula (I), and the additive resin and the binder resin added as necessary are not particularly limited. The binder resin is preferably about 1 to 10% by weight in the total amount.
If the binder resin ratio is less than 1% by weight, the film strength of the single-layer type photosensitive layer may be lowered. Conversely, if the binder resin ratio exceeds 10% by weight, the function of the single-layer type photosensitive layer is lowered. There is a fear.

  The monolayer type photosensitive layer comprises a charge generating material, an enamine compound represented by the general formula (1) as a charge transport material, a diamine fat represented by the general formula (I), and additives such as an antioxidant as necessary. Is dissolved or dispersed in a suitable organic solvent to prepare a coating solution for forming a photosensitive layer, and this coating solution is applied to the surface of the conductive support or the surface of the undercoat layer formed on the conductive support. And then dried to remove the organic solvent. More specifically, for example, a coating solution for forming a single-layer photosensitive layer is prepared by dissolving or dispersing a constituent material in a resin solution obtained by dissolving a binder resin in an organic solvent.

  In preparing the coating solution for forming a single-layer type photosensitive layer, it is particularly preferable to first dissolve the charge transport material in a solvent and then dissolve the binder resin. According to this method, the molecular dispersibility of the charge transport material in the binder resin is improved, and the initial sensitivity is improved by suppressing the crystallization of the potential local charge transport material in the film. Potential stability during repeated use, good image characteristics, and the like are imparted.

  Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; tetrahydrofuran (THF) , Ethers such as dioxane, dibenzyl ether, dimethoxymethyl ether, 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, isophorone; esters such as methyl benzoate, ethyl acetate, butyl acetate, diphenyl sulfide Sulfur-containing solvents such as: Fluorinated solvents such as hexafluoroisopropanol; non-protons such as N, N-dimethylformamide and N, N-dimethylacetamide Such as a polar solvent and the like, which may be used alone or as a mixed solvent. A mixed solvent obtained by adding alcohols, acetonitrile, or methyl ethyl ketone to such a solvent can also be used. Of these solvents, tetrahydrofuran is particularly preferred.

Prior to dissolving or dispersing the constituent materials in the resin solution, the charge generating material and other additives may be pre-ground.
The preliminary pulverization can be performed using a general pulverizer such as a ball mill, a sand mill, an attritor, a vibration mill, or an ultrasonic disperser.
The dissolution or dispersion of the constituent materials in the resin solution can be performed using, for example, a general disperser such as a paint shaker, a ball mill, or a sand mill. At this time, it is preferable to appropriately set the dispersion condition so that impurities are generated from the container and the members constituting the disperser due to wear and the like and are not mixed into the coating liquid.
When the conductive support is a sheet, the application method of the single layer type photosensitive layer forming coating solution is a baker applicator method, a bar coater method, a casting method, a spin coating method, or the like, where the conductive support is a drum. Examples of the method include a spray method, a vertical ring method, and a dip coating method.

Although the film thickness of a single layer type photosensitive layer is not specifically limited, 5-100 micrometers is preferable and 10-50 micrometers is especially preferable. If the film thickness of the single-layer type photosensitive layer is less than 5 μm, the charge holding ability on the surface of the photoreceptor may be lowered. Conversely, if the film thickness of the single-layer type photosensitive layer exceeds 100 μm, the productivity of the photoreceptor is reduced. There is a risk.
[Laminated Photosensitive Layer 204]
The laminated photosensitive layer includes a charge generation layer 205 and a charge transport layer 206.
The photoreceptor provided in the image forming apparatus of the present invention has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material stacked in this order on a conductive support made of a conductive material. It is preferable that the laminated type photosensitive layer is laminated. Since it is possible to select the most suitable material for each of the charge generation function and the charge transport function, it is possible to obtain a photoconductor having higher sensitivity and higher durability with increased stability during repeated use. The image forming apparatus using the same can achieve higher sensitivity and higher durability.

[Charge generation layer 205]
The charge generation layer 3 contains at least a charge generation material and a binder resin.
As the charge generation material, one or more of the same charge generation materials as those contained in the single-layer type photosensitive layer can be used.
As the binder resin, one or more of the same binder resins as those contained in the single-layer type photosensitive layer can be used.
The use ratio of the charge generation material and the binder resin is not particularly limited. Preferably, the charge generation material is contained in an amount of 10 to 99% by weight in the total amount of the charge generation material and the binder resin, and the balance is the binder resin. It is.
If the ratio of the charge generation material is less than 10% by weight, the sensitivity may be lowered. Conversely, if the ratio of the charge generation material exceeds 99% by weight, not only the film strength of the charge generation layer is decreased, but also the charge generation. This is called a black spot where the dispersibility of the substance decreases and the coarse particles increase, the surface charge other than that which should be erased by exposure decreases, and image defects, especially toner adheres to the white background and minute black spots are formed. There is a possibility that a lot of fogging of the image occurs.

  In addition to the two essential components, the charge generation layer may be one or more selected from a hole transport material, an electron transport material, an antioxidant, a dispersion stabilizer, a sensitizer, and the like, if necessary. Each may contain an appropriate amount. As a result, the potential characteristics are improved, the stability of the coating solution for forming a charge generation layer, which will be described later, is increased, fatigue deterioration during repeated use of the photoreceptor is reduced, and durability can be improved.

The charge generation layer 3 is prepared by dissolving or dispersing a charge generation material, a binder resin and, if necessary, other additives in an appropriate organic solvent to prepare a coating solution for forming a charge generation layer. It can be formed by applying to the surface of the body 1 or the surface of the undercoat layer formed on the conductive support 1, and then drying to remove the organic solvent. More specifically, for example, a charge generating layer forming coating solution is prepared by dissolving or dispersing a charge generating substance and other additives as required in a resin solution obtained by dissolving a binder resin in an organic solvent. To do.
Other processes and conditions are in accordance with the formation of the single-layer type photosensitive layer.
The organic solvent can use 1 type (s) or 2 or more types of the same solvent as what is used for preparation of the coating liquid for formation of a single layer type photosensitive layer.

  The thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, particularly preferably 0.1 to 1 μm. This is because if the film thickness of the charge generation layer is less than 0.05 μm, the efficiency of light absorption may be reduced and the sensitivity may decrease. Conversely, if the film thickness of the charge generation layer exceeds 5 μm, In this case, the charge transport in this process becomes a rate-determining step in the process of erasing the charge on the surface of the photoreceptor, and the sensitivity may be lowered.

[Charge transport layer 206]
The charge transport layer contains at least an enamine compound represented by the general formula (1) as a charge transport material, a diamine compound represented by the general formula (I), and a binder resin.
As the enamine compound represented by the general formula (1) as the charge transport material, one or more enamine compounds similar to those contained in the single-layer type photosensitive layer can be used.
As the diamine compound represented by the general formula (I), one or more of the same diamine compounds as those contained in the single-layer type photosensitive layer can be used.
As the binder resin, one or more of the same binder resins as those contained in the single-layer type photosensitive layer can be used.
The proportion of each component used is the same as that of the single-layer type photosensitive layer.
In addition to the three essential components, the charge transport layer may contain an additive such as an antioxidant similar to that contained in the single-layer type photosensitive layer, if necessary.

The charge transport layer 4 comprises an enamine compound represented by the general formula (1) as a charge transport material, a diamine compound represented by the general formula (I), a binder resin, and other additives as required in a suitable organic solvent. It can be formed by dissolving or dispersing to prepare a coating solution for forming a charge transport layer, coating the coating solution on the surface of the charge generation layer 3, and then drying to remove the organic solvent. More specifically, for example, the charge transport layer is prepared by dissolving or dispersing the charge transport material, the diamine compound of the present invention and, if necessary, other additives in a resin solution obtained by dissolving a binder resin in an organic solvent. A forming coating solution is prepared.
Other processes and conditions are in accordance with the formation of the single-layer type photosensitive layer.

  Although the film thickness of a charge transport layer is not specifically limited, 5-50 micrometers is preferable and 10-40 micrometers is especially preferable. If the thickness of the charge transport layer is less than 5 μm, the charge holding ability on the surface of the photoreceptor may be lowered. Conversely, if the thickness of the charge transport layer exceeds 50 μm, the resolution of the photoreceptor may be lowered.

[Undercoat layer (intermediate layer) 208]
In the photoreceptor provided in the image forming apparatus of the present invention, an undercoat layer 208 may be provided between the conductive support 201 and the laminated photosensitive layer 204 or the single-layered photosensitive layer 204 ′.
The undercoat layer has a function of preventing charge injection from the conductive support to the single-layer type photosensitive layer or the laminated type photosensitive layer. That is, the decrease in chargeability of the single-layer type photosensitive layer or the multilayer type photosensitive layer is suppressed, the decrease in surface charge other than the portion to be erased by exposure is suppressed, and the occurrence of image defects such as fog is prevented. In particular, during image formation by the reversal development process, it is possible to prevent the occurrence of image fogging called black spots in which minute black dots made of toner are formed on a white background portion.
In addition, the undercoat layer covering the surface of the conductive support reduces the degree of unevenness, which is a defect on the surface of the conductive support, and makes the surface uniform, thereby forming a single layer type photosensitive layer or a multilayer type photosensitive layer. The film property can be improved, and the adhesion between the conductive support and the single layer type photosensitive layer or the multilayer type photosensitive layer can be improved.

The undercoat layer is generally composed of an inorganic layer, an organic layer, and an organic layer containing conductive or semiconductive fine particles such as metal fine particles or metal oxides.
The undercoat layer made of an organic layer is prepared, for example, by preparing a coating solution for forming an undercoat layer by dissolving a binder resin in an appropriate solvent, applying the coating solution to the surface of the conductive support, and drying the organic solvent. Can be formed by removing.
Examples of the binder resin include natural polymeric materials such as casein, gelatin, polyvinyl alcohol, and ethyl cellulose, in addition to the same binder resin as that contained in the single-layer type photosensitive layer, and one or more of these may be used. Can be used. Of these binder resins, polyamide resins are preferable, and alcohol-soluble nylon resins are particularly preferable.
Examples of alcohol-soluble nylon resins include copolymerized nylons such as 6-nylon, 66-nylon, 610-nylon, 11-nylon, and 12-nylon, and modified nylons such as N-alkoxymethyl-modified nylon and N-alkoxyethyl-modified nylon. Etc.

Examples of the solvent for dissolving or dispersing the binder resin include water, alcohols such as methanol, ethanol, and butanol, glymes such as methyl carbitol and butyl carbitol, and mixed solvents obtained by mixing two or more of these solvents. Can be mentioned.
When a more preferable alcohol-soluble nylon resin is used as the binder resin, a lower alcohol group having 1 to 4 carbon atoms, for example, dichloromethane, chloroform, 1,2-dichloroethane, 1,2-dichloropropane, toluene, tetrahydrofuran, 1, It is preferably composed of a single organic solvent and a mixed organic solvent selected from the group consisting of other organic solvents such as 3-dioxolane.
The mixed organic solvent described above is more suitable for coating defects in the undercoat layer when forming the undercoat layer by dip-coating the conductive support in the undercoat layer coating solution than the alcohol-based single solvent. Unevenness can be prevented, the photosensitive layer formed thereon can be uniformly applied, and a photoreceptor having very excellent image characteristics without film defects can be formed. Further, when titanium oxide is used as the metal oxide particles described later, the dispersibility is improved, and the storage stability of the coating solution can be prolonged and the coating solution can be regenerated.
Other processes and conditions are in accordance with the formation of the single-layer type photosensitive layer.

When the undercoat layer is an organic layer containing conductive or semiconductive fine particles such as metal fine particles or metal oxides, a conductive material such as metal or metal oxide is added to the coating solution for forming the undercoat layer. Alternatively, semiconductive fine particles may be added.
These fine particles of metal or metal oxide can easily adjust the volume resistance value of the undercoat layer, can further suppress charge injection into the single-layer type photosensitive layer or the multilayer type photosensitive layer, and can be sensitive to various environments. The body's electrical characteristics can be maintained.

Examples of the metal fine particles include metal fine particles such as aluminum, copper, tin, zinc, and titanium.
Examples of the metal oxide particles include fine particles such as titanium oxide, aluminum oxide, aluminum hydroxide, and tin oxide. Crystal forms of titanium oxide include anatase type, rutile type, and amorphous. Any of these may be used, or two or more types may be mixed. The surface of the titanium oxide fine particles is preferably coated with a metal oxide such as aluminum oxide or zirconium oxide or a mixture thereof. This is because the binder resin does not dissolve or swell in the solvent used when forming the photoreceptor layer on the undercoat layer, and has excellent adhesion to the conductive support. This is because characteristics such as having flexibility are required.

Examples of the undercoat layer made of an organic layer include inorganic layers such as an aluminum anodized film (alumite), aluminum oxide, and aluminum hydroxide. In the case where the constituent material of the conductive support is aluminum, a layer containing alumite (alumite layer) is formed on the surface thereof to form an undercoat layer made of an inorganic layer.
The thickness of the undercoat layer is not particularly limited, but is preferably 0.01 to 20 μm, particularly preferably 0.05 to 10 μm. If the thickness of the undercoat layer is less than 0.01 μm, scratch resistance on the surface of the photoreceptor may be inferior and durability may be insufficient. Conversely, if it exceeds 20 μm, the resolution of the photoreceptor may be reduced. is there.

[Surface protective layer]
In the photoreceptor provided in the image forming apparatus of the present invention, a surface protective layer (not shown) may be provided on the surface of the laminated photosensitive layer 204 or the single-layered photosensitive layer 204 ′.
The surface protective layer has a function of improving the durability of the photoreceptor and usually contains a charge transport material and a binder resin.
As the charge transport material, one or more of the same charge transport materials as those contained in the single-layer type photosensitive layer can be used.
As the binder resin, one or more of the same binder resins as those contained in the single-layer type photosensitive layer can be used.

The surface protective layer is prepared by, for example, preparing a surface protective layer forming coating solution by dissolving or dispersing a charge transport material and a binder resin in an appropriate organic solvent, and using the surface protective layer forming coating solution as a single-layer photosensitive layer. Or it can form by apply | coating to the surface of a lamination type photosensitive layer, and removing an organic solvent by drying. As the organic solvent used here, the same organic solvent used for forming the photosensitive layer can be used.
Other processes and conditions are in accordance with the formation of the single-layer type photosensitive layer.
The organic solvent can use 1 type (s) or 2 or more types of the same solvent as what is used for preparation of the coating liquid for formation of a single layer type photosensitive layer.
Although the film thickness of a surface protective layer is not specifically limited, 0.5-10 micrometers is preferable and 1-5 micrometers is especially preferable. If the thickness of the surface protective layer 5 is less than 0.5 μm, the surface resistance of the photoreceptor is inferior and the durability may be insufficient. Conversely, if it exceeds 10 μm, the resolution of the photoreceptor may be reduced. There is.

Next, the image forming apparatus of the present invention will be described in detail with reference to FIG.
FIG. 1 is a schematic cross-sectional view of a tandem type color multifunction peripheral equipped with a photoreceptor, showing an example of the image forming apparatus of the present invention.
As shown in FIG. 1, an image forming apparatus 1 includes a photosensitive drum 3 that carries a developer image (toner image) formed by a developer (toner) that matches each hue in accordance with color-separated image information. A plurality of process printing units 20 (20a, 20b, 20c, 20d) constituting an image forming unit having (3a, 3b, 3c, 3d) and toner images formed on the photosensitive drum 3 are temporarily stacked. An endless intermediate transfer belt (intermediate transfer member) 7 for transfer, a transfer portion (transfer mechanism) 11 for transferring a toner image from the intermediate transfer belt 7 to a recording sheet, and a toner image transferred to the recording sheet by heat fixing And a transfer belt cleaning unit (cleaning unit) 9 for removing toner remaining on the intermediate transfer belt 7 without being transferred from the intermediate transfer belt 7 onto the recording paper.

First, the overall configuration of the image forming apparatus 1 will be described.
As shown in FIG. 1, an image forming apparatus 1 is a so-called digital color multi-function peripheral that color-separates image information, forms an image for each hue, and outputs a color image. A multi-color image or a single-color image is formed on a recording sheet based on a print job from an information processing apparatus (not shown) such as a personal computer connected to the outside. It is. As the recording paper, resin sheets and metal sheets can be used as required in addition to paper.

  The image forming unit 108 forms a multicolor image using each color of yellow (Y), cyan (C), magenta (M), and black (BK) by an electrophotographic method. The unit 50, the process printing unit 20, the fixing unit 12, a transfer belt unit 8 as transfer means including the intermediate transfer belt 7, an intermediate transfer roller 6 (6 a, 6 b, 6 c, 6 d), and a transfer belt cleaning unit 9. ing.

The schematic configuration of the image forming unit 108 is that a fixing unit 12 is disposed on the upper end of one end of the casing 1 a of the image forming apparatus 1, and transferred from one end side to the other end side of the casing 1 a below the fixing unit 12. A belt unit 8 is disposed, a process printing unit 20 is disposed below the transfer belt unit 8, and an exposure unit 50 is disposed below the process printing unit 20.
A transfer belt cleaning unit 9 is provided on the other end side of the transfer belt unit 8. Further, a paper discharge tray 15 is provided above the image forming unit 108 adjacent to the fixing unit 12. A paper feeding unit 109 is configured below the image forming unit 108.

In the image forming apparatus 1, as the process printing unit 20, four process printing units 20a, 20b, 20c, and 20d corresponding to each color of black (BK), magenta (M), cyan (C), and yellow (Y) are provided. They are sequentially provided along the intermediate transfer belt 7. By the arrangement order of the respective colors, the toner images without color blur are superimposed on the intermediate transfer belt 7.
The process print unit 20d of the hue that is first transferred among the toner images transferred onto the intermediate transfer belt 7, that is, the process print unit 20d of the hue that is disposed farthest from the transfer unit 11 has a yellow hue. In this case, a yellow toner image is first formed on the intermediate transfer belt 7.

These process printing units 20a, 20b, 20c, and 20d are arranged in parallel in a substantially horizontal direction (left and right direction in the drawing) in the housing 1a, and the photosensitive drums 3a, 3b, which are image carriers for each color. 3c, 3d, chargers (charging means) 5a, 5b, 5c, 5d for charging the photosensitive drums 3a, 3b, 3c, 3d, developing devices (developing means) 2a, 2b, 2c, 2d, cleaner unit 4a, 4b, 4c, 4d, etc. are provided.
Here, the symbols a, b, c, and d attached to the components corresponding to the respective colors correspond to the respective colors of black (BK), magenta (M), cyan (C), and yellow (Y). However, in the following description, the constituent elements provided for each color are collectively shown in the photosensitive drum 3, except for the case where the constituent elements corresponding to a specific color are specified. The charger 5, the developing device 2, and the cleaner unit 4 are described.

  The photosensitive drum 3 is disposed so that a part of the outer peripheral surface thereof is in contact with the surface of the intermediate transfer belt 7, and the charger 5, the developing device 2, and the cleaner as an electric field generator along the outer peripheral surface of the drum. Units 4 are arranged close to each other.

  The charger 5 is a roller-type charger and is disposed so as to contact the outer peripheral surface of the photosensitive drum 3 on the substantially opposite side to the position where the transfer belt unit 8 is disposed across the photosensitive drum 3. In this embodiment, a roller-type charger that generates less ozone and NOx is used as the charger 5, but a brush-type charger, a charger-type charger, or the like may be used instead of the roller-type charger.

The exposure unit 50 applies laser light to each photosensitive drum 3 for each color based on the image data for printing, with respect to each photosensitive drum 3 whose drum surface is charged to a uniform potential by the charger 5. And a function of generating an electrostatic latent image on the surface of the photosensitive drum 3.
The exposure unit 50 mainly includes a laser scanning unit (LSU) 51 including a laser irradiation unit 51a, a polygon mirror 52, and reflection mirrors 53a, 53b, 53c, 53d, 54a, 54b that reflect laser light for each color, 54c and the like, and is an optical scanning device that emits laser light emitted from a laser irradiation unit 51a to a plurality of photosensitive drums 3a, 3b, 3c, and 3d, respectively.

  A laser scanning unit 51 is disposed at one end of the bottom of the housing 50a, and the polygon mirror 52, the fθ lens 55, the reflection mirrors 53a, 53b, 53c, and 53d are arranged from one end to the other end. Arranged in order.

The laser scanning unit 51 may use a writing head in which light emitting elements such as EL (Electro Luminescence) and LED (Light Emitting Diode) are arranged in an array instead of the laser irradiation unit 51a.
The fθ lens 55 includes two lenses. For example, the fθ lens 55 includes a cylinder lens 55a as a first lens and a toroidal lens 55b as a second lens.
On the upper surface of the housing 50a, an opening is formed that is long open along the direction along the axis of the photosensitive drum at a position facing the photosensitive drums 3a, 3b, 3c, and 3d. The condensing lenses 56a, 56b, 56c, and 56d that transmit the laser beams reflected by the reflecting mirrors 53d, 54a, 54b, and 54c and focus on the respective photosensitive drums 3a, 3b, 3c, and 3d are disposed. Has been.

The developing device 2 applies black (BK), magenta (M), cyan (C), and yellow (Y) to the electrostatic latent image formed by the exposure unit 50 described above on the outer peripheral surface of the photosensitive drum 3. A toner is supplied to make a visible image.
The developing device 2 stores toner of each color of black (BK), magenta (M), cyan (C), and yellow (Y) for each developing device 2, and rotates the photosensitive drum (in the drawing). (In the direction of arrow A) of FIG. Then, each color toner is supplied to the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 3 so as to be visualized.

The cleaner unit 4 removes and collects the toner remaining on the surface of the photosensitive drum 3 after the toner image on the surface of the photosensitive drum 3 developed by the developing device 2 is transferred to the intermediate transfer belt 7. The cleaner unit 4 is disposed downstream of the intermediate transfer belt 7 and upstream of the charger 5 along the photosensitive drum rotation direction.
In addition, the cleaner unit 4 includes a cleaning blade, and the cleaning blade is disposed in contact with the outer peripheral surface of the photosensitive drum 3 so as to scrape and collect residual toner on the photosensitive drum 3. Yes.

The transfer belt unit 8 is configured separately from the apparatus main body, and is detachably attached to the apparatus main body. The configuration mainly includes an intermediate transfer belt 7, a transfer belt drive roller 8-1, a transfer belt driven roller 8-2, a transfer belt tension mechanism 8-3, and intermediate transfer rollers 6a, 6b, 6c, and 6d. ing.
Then, the transfer belt unit 8 sequentially superimposes and transfers the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 7, thereby forming a color toner image (multicolor toner image) on the intermediate transfer belt 7. It has the function to form.
The intermediate transfer belt 7 is formed in an endless shape using chloroprene rubber as a material.
In addition, as a configuration of the intermediate transfer belt different from the present embodiment, a film having a thickness of about 75 μm to 120 μm using polyimide, polycarbonate, a thermoplastic elastomer alloy, or the like as a material may be formed endlessly. .

  Further, the intermediate transfer belt 7 has a transfer belt driving roller 8-1, a transfer belt driven roller 8-2, a transfer belt tension mechanism 8-3, an intermediate transfer so that the surface thereof is in contact with the outer peripheral surface of the photosensitive drum 3. It is stretched by a roller 6 and is configured to move in the sub-scanning direction (the direction of arrow B in the figure) by the driving force of the transfer belt driving roller 8-1.

The transfer belt drive roller 8-1 is disposed on one end side of the housing 1a, drives the intermediate transfer belt 7 to convey the intermediate transfer belt 7, and superimposes the intermediate transfer belt 7 and the recording paper. In this state, it is provided so as to convey the recording paper while being sandwiched between the transfer unit 11 (transfer roller 11a) and pressed.
The transfer belt driven roller 8-2 is disposed on the other end side of the housing 1a, and the intermediate transfer belt 7 is installed substantially horizontally from one end side to the other end side of the housing 1a together with the transfer belt driving roller 8-1. ing.

The intermediate transfer roller 6 is disposed in an inner space of the intermediate transfer belt 7 wound from the transfer belt driving roller 8-1 to the transfer belt driven roller 8-2, and presses the inner surface of the intermediate transfer belt 7, The outer surface of the intermediate transfer belt 7 is provided so as to contact a part of the outer peripheral surface of the photosensitive drum 3 to obtain a predetermined nip amount.
The intermediate transfer roller 6 includes a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm, and an outer peripheral surface of the metal shaft is covered with an elastic material having conductivity such as EPDM or urethane foam.

The intermediate transfer roller 6 configured in this manner is opposite to the high-voltage transfer bias, that is, the toner charging polarity (−), in order to transfer the toner image formed on the photosensitive drum 3 to the intermediate transfer belt 7. A high voltage of polarity (+) is applied, and the high voltage is uniformly applied to the intermediate transfer belt 7 by an elastic material.
In this embodiment, an intermediate transfer roller using a roller-shaped electrode is used as a configuration for performing intermediate transfer. However, as another method, a brush-shaped transfer electrode (transfer brush) is used as an intermediate transfer. The belt 7 may be in contact with the back side.

  On each of the above-described photosensitive drums 3, a visualized toner image (electrostatic image) corresponding to each hue is laminated by the intermediate transfer belt 7 and becomes image information input to the apparatus. The image information stacked in this way is transferred to a recording sheet by a transfer unit 11 disposed at a contact position of the intermediate transfer belt 7.

  The transfer unit 11 constitutes transfer means for transferring the developer image transferred to the intermediate transfer belt 7 to a recording sheet, and includes a transfer roller 11a. The transfer roller 11a is connected to the transfer belt drive roller 8-1. It is arranged so as to be substantially horizontal and parallel to the intermediate transfer belt 7 wound around the transfer belt driving roller 8-1, so as to come into pressure contact with the intermediate transfer belt 7 at a predetermined nip via the conveyance belt 11b.

The transfer roller 11a applies a voltage for transferring the multicolor toner image formed on the intermediate transfer belt 7 onto the recording paper, that is, a high voltage having a polarity (+) opposite to the toner charging polarity (-). It is configured to be.
Further, one of the transfer roller 11a and the transfer belt drive roller 8-1 is made of a hard material (metal or the like), and the other is a soft material (elastic rubber roller, foaming resin roller or the like) on the surface of the core metal. Is constituted by an elastic roller covered with As a result, a nip having a predetermined width is constantly obtained.

A registration roller 14 is provided below the transfer belt drive roller 8-1 and the transfer unit 11. The registration roller 14 is configured to convey the leading end of the recording paper supplied from the paper feeding unit 109 and the leading end of the toner image on the intermediate transfer belt 7 to the transfer unit 11 side.
Further, as described above, the toner adhering to the intermediate transfer belt 7 due to contact with the photosensitive drum 3 or the toner remaining on the recording paper without being transferred onto the recording paper by the intermediate transfer roller 6 is used in the next step. Since it causes toner color mixing, it is set so as to be removed and collected by the transfer belt cleaning unit 9.

  The transfer belt cleaning unit 9 is provided in the vicinity of the transfer belt driven roller 8-2, and is disposed so as to contact (or slide) the intermediate transfer belt 7, and the intermediate transfer belt by the cleaning blade 9a. 7 and a box-shaped toner collecting portion 9b for temporarily storing the toner (waste toner) scraped off from the residual toner on the intermediate transfer belt 7. The residual toner on the intermediate transfer belt 7 is scraped and collected. The collected waste toner is conveyed to a waste toner collection container 9c.

  Further, the transfer belt cleaning unit 9 is disposed in the vicinity of the process printing unit 20a on the upstream side in the moving direction of the intermediate transfer belt 7 from the process printing unit 20a. The portion of the intermediate transfer belt 7 where the cleaning blade 9a contacts the outer surface is supported by the transfer belt driven roller 8-2 on the inner surface.

As shown in FIG. 1, the fixing unit 12 includes a pair of fixing rollers 12a formed of a heating roller 31 and a pressure roller 32, and a conveying roller 25-5 above the fixing roller 12a. It is carried in from below the fixing roller 12a and carried out upward.
Further, above the fixing unit 12, a paper discharge roller 25-6 is provided adjacent to the transport roller 25-5, and the recording paper transported from the transport roller 25-5 is discharged by the paper discharge roller 25-6. The recording paper is discharged onto the paper tray 15.

The fixing of the toner image by the fixing unit 12 is controlled by controlling heating means (not shown) such as a heater lamp provided inside or close to the heating roller 31 based on a detection value of a temperature detector (not shown). The heating roller 31 is kept at a predetermined temperature (fixing temperature), and the recording paper on which the toner image is transferred is heated and pressed while being rotated and conveyed while being sandwiched between the heating roller 31 and the pressure roller 32. The toner image is thermally fixed.
The paper feeding unit 109 includes a plurality of paper feeding trays 10 for storing recording papers used for image formation, and supplies the recording papers one by one from the paper feeding tray 10 to the image forming unit 108. .

The paper feed tray 10 is provided below the image forming unit 108 and the exposure unit 50 in the housing 1a and accommodates a large amount of recording paper having a size defined by the specifications of the apparatus or a size predetermined by the user. It is possible.
Pickup rollers 16 are respectively provided on one end portion (left end portion in the figure) of the paper feed tray 10, and the surface of one end portion of the recording paper at the top of the recording paper set in the paper feed tray 10 The rollers are brought into contact with each other and reliably fed out one by one by the frictional resistance of the rollers.

A paper discharge tray 15 is provided at the top of the image forming apparatus 1 so that printed recording paper is discharged face down and stacked.
In addition, the sheet feeding unit 109 has a substantially vertical sheet conveyance path S for conveying the recording sheet in the sheet feeding tray 10 to the sheet discharge tray 15 provided above via the transfer unit 11 and the fixing unit 12. Is configured.
Further, in the vicinity of the paper conveyance path S from the paper feed tray 10 to the paper discharge tray 15, a pickup roller 16, a registration roller 14, a transfer unit 11, a fixing unit 12, and a conveyance roller 25 (25-) for conveying recording paper. 1-25-8) are arranged.

  The registration roller 14 temporarily stops the recording sheet conveyed by the sheet conveyance path S at a predetermined position and measures the next conveyance timing. The recording paper has a function of conveying the recording paper to the transfer section 11 at a timing at which the leading edge of the toner image on the intermediate transfer belt 7 is synchronized with the leading edge of the recording paper.

The recording paper transported from the paper feed tray 10 is transported to the registration rollers 14 by the transport rollers 25-1 to 25-4 in the transport path, and is temporarily stopped. The toner image on the transfer belt 7 is conveyed to the transfer unit 11 at a timing for aligning the leading end of the toner image.
The transferred recording sheet is transferred with the toner image on the intermediate transfer belt 7 by the transfer unit 11 and further transferred to the fixing unit 12 where the unfixed toner on the recording sheet is melted by heat and fused to the recording sheet. To do. After passing through the fixing unit 12, it is naturally cooled and fixed on the recording paper. Then, the recording paper is discharged onto the paper discharge tray 15 from the paper discharge roller 25-6 via the transport roller 25-5.
The recording paper after the fixing of the multicolor toner image is conveyed to the reverse paper discharge path of the paper conveyance path S by the conveyance rollers 25-5 and 25-6, and is reversed (the multicolor toner image is placed on the lower side). Toward the paper discharge tray 15.

A control board 40 is disposed below the paper discharge tray 15.
The control board 40 provides a microcomputer for controlling the operation of each part of the image forming apparatus 1, a ROM for storing a control program executed by the microcomputer, a work area for processing of the microcomputer, and a storage area for image data. RAM to be used.

  The microcomputer functions as a control unit by executing a control program. The functions of the control unit realize the above-described image formation, toner image transfer, recording paper conveyance, fixing unit temperature control, and the like.

  The control board 40 has an input circuit and an output circuit. The input circuit is configured such that signals from sensors arranged in the respective units in the image forming apparatus 1 are input, and processing by the microcomputer is executed using the input signals. The output circuit is a circuit that outputs a signal for driving a load disposed in each part.

The image forming unit of the image forming apparatus of the present invention preferably includes an intermediate transfer member. Thereby, a color image forming apparatus capable of high-speed printing can be provided.
The charging means in the image forming unit of the image forming apparatus of the present invention is preferably a contact charging method. As a result, the ozone amount and the NOx amount can be suppressed to be smaller than those of the conventional corona charging method, and a high-speed and highly durable image forming apparatus can be provided.

The present invention will be specifically described below with reference to production examples, examples and comparative examples, but the present invention is not limited to these production examples and examples.
In addition, the chemical structure, molecular weight, and elemental analysis of the compound obtained by the manufacture example were measured with the following apparatuses and conditions.

(Chemical structure)
Nuclear magnetic resonance apparatus: NMR (Bruker Biospin, model: DPX-200)
Sample preparation About 4mg / 0.4m (CDCl3)
Measurement mode 1H (normal), 13C (normal, DPET-135)

(Molecular weight)
Molecular weight measuring device: LC-MS (manufactured by Thermoquest,
(Finegan LCQ Deca Mass Spectrometer System)
LC column GL-Sciences Inertsil ODS-3 2.1 × 100mm
Column temperature 40 ° C
Eluent methanol: water = 90: 10
Sample injection volume 5 μl
Detector UV254nm and MS ESI

(Elemental analysis)
Elemental analysis device: Perkin Aelmer, Elemental Analysis 2400
Sample amount: Weigh accurately about 2 mg Gas flow rate (ml / min): He = 1.5, O2 = 1.1, N2 = 4.3
Combustion tube temperature setting: 925 ° C
Reduction tube temperature setting: 640 ° C
In addition, the elemental analysis was analyzed by the simultaneous determination method of carbon (C), hydrogen (H) and nitrogen (N) by the differential thermal conductivity method.

(Production Example 1)
According to the following reaction formula, Exemplified Compound No. 1 (Structural Formula (III)) was produced.

[Production of Amine-Bisaldehyde Intermediate (7aa)]
In 50 ml of anhydrous 1,4-dioxane, 6.06 g (1.0 equivalent) of 4,4′-bis (chloromethyl) biphenyl and 10.0 g (2.1 equivalent) of dibenzylamine were added, and iced on an ice bath. Cooled under cold. To this solution, 6.86 g (2.2 equivalents) of N, N-diisopropylethylamine was gradually added. Then, it heated gradually, raised reaction temperature to 100-110 degreeC, and stirred for 4 hours, heating so that 100-110 degreeC might be maintained. After completion of the reaction, the reaction solution is allowed to cool, and the resulting precipitate is collected by filtration, washed thoroughly with water, and re-reused with a mixed solvent of ethanol and ethyl acetate (ethanol: ethyl acetate = 8: 2 to 7: 3). By performing crystallization, 12.1 g of a white powdery compound was obtained.

As a result of chemical analysis of the obtained white powdery compound,
Nuclear magnetic resonance equipment: NMR
1H-NMR spectrum (normal) showed δ (ppm) = 3.58 (S.12H) 7.07 7.84 (m.28H).
Further, the 13C-NMR spectrum (usually DPET-135) has δ = 57.80 (CH2, signal intensity 2), 58.07 (CH2, signal intensity 4), 126.94 (CH, signal intensity 4), 128.32 (CH, signal intensity 8), 128.72 (CH, signal intensity 4), 128.83 (CH, signal intensity 4), 128.85 (CH, signal intensity 8), 138.29 (C, Signal intensity 2), 139.25 (C, signal intensity 4), and 139.28 (C, signal intensity 2) were shown.
Furthermore, the molecular weight measuring device: LC-MS is exemplified by Compound No. A peak corresponding to molecular ion [M + H] + in which a proton was added to 1 (calculated molecular weight: 572.30) was observed at 573.2.

The elemental analysis values of the white powdery compound were as follows.
<Exemplary Compound No. Elemental analysis value of 1>
Theoretical value C: 88.07%, H: 7.04%, N: 4.89%
Actual value C: 87.25%, H: 6.88%, N: 4.42%
As described above, from the results of analysis such as NMR, LC-MS, and elemental analysis, the obtained white powdery compound was found to be Compound No. 1 diamine compound (yield: 87.5%). Moreover, from the analysis result of HPLC at the time of LC-MS measurement, the obtained exemplary compound No. The purity of 1 was 99.0%.

(Production Examples 2 to 10)
The same operation as in Production Example 1 was carried out using the amine compounds represented by the general formulas (4) and (5) and the raw material compounds shown in Table 3 as the dihalogen compounds represented by the general formula (6). No. 2, 4, 8, 14, 22, 29, 38, 50 and 53 were produced, respectively. In Table 3, Exemplified Compound No. 1 raw material compounds are also shown.

  In addition, Table 4 shows the elemental analysis values, the calculated molecular weight values, and the actually measured values [M + H] obtained by LC-MS of the respective exemplary compounds obtained in Production Examples 1 to 10.

  A photoreceptor was produced using the diamine compound (Exemplary Compound No. 1) produced in Production Example 1 as follows. As the conductive support, a drum-shaped support made of aluminum having a diameter of 30 mm and a total length of 340 mm was used.

  7 parts by weight of titanium oxide (trade name: Taibake TTO55A, manufactured by Ishihara Sangyo Co., Ltd.) and 13 parts by weight of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.), 159 parts by weight of methyl alcohol and 1,3- In addition to a mixed solvent with 106 parts by weight of dioxolane, dispersion treatment was performed for 8 hours with a paint shaker to prepare a coating solution for forming an undercoat layer. This undercoat layer forming coating solution was applied to an aluminum drum-like support as a conductive support by an immersion method, and then naturally dried to form an undercoat layer having a thickness of 1 μm.

  Next, 1 part by weight of titanyl phthalocyanine and 1 part by weight of butyral resin as charge generation materials were mixed with 98 parts by weight of methyl ethyl ketone, and dispersed with a paint shaker to prepare a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was applied to the surface of the undercoat layer previously provided by an immersion method and naturally dried to form a charge generation layer having a thickness of 0.4 μm.

  Subsequently, Exemplified Compound No. 1 as a charge transport material 100 parts by weight of 1 enamine compound, 90 parts by weight of two types of polycarbonate resins each having a repeating unit represented by the following structural formula (viscosity average molecular weights 38,000 and 21,500, respectively), exemplified compound No. produced in Production Example 1 . 5 parts by weight of the diamine compound 1 and 0.02 parts by weight of silicon oil were mixed, and a coating solution for forming a charge transport layer having a solid content of 25% by weight was prepared using tetrahydrofuran as a solvent. This charge transport layer forming coating solution was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 130 ° C. for 1 hour to form a charge transport layer having a thickness of 25 μm. In this way, the multilayer photoreceptor shown in FIG. 3 was prepared.

(Example 2)
Exemplified compound No. 1 as a charge transport material. 1 instead of the enamine compound of Ex. A laminated photoreceptor was prepared in the same manner as in Example 1 except that the enamine compound No. 3 was used.

(Example 3)
Exemplified compound No. 1 as a charge transport material. 1 instead of the enamine compound of Ex. A laminated photoreceptor was produced in the same manner as in Example 1 except that 61 enamine compound was used.

Example 4
Two kinds of polycarbonate resins (viscosity average molecular weights 38,000 and 21,500, respectively) instead of 90 parts by weight, respectively, two kinds of polycarbonate resins (viscosity average molecular weights 50,000 and 21,500, respectively) having the same repeating unit A laminated photoreceptor was produced in the same manner as in Example 1 except that 50 parts by weight was used.

(Example 5)
Two kinds of polycarbonate resins (viscosity average molecular weights 38,000 and 21,500, respectively) instead of 90 parts by weight, respectively, two kinds of polycarbonate resins (viscosity average molecular weights 50,000 and 21,500, respectively) having the same repeating unit A laminated photoreceptor was prepared in the same manner as in Example 1 except that 60 parts by weight was used.

(Example 6)
Two kinds of polycarbonate resins (viscosity average molecular weights 38,000 and 21,500, respectively) instead of 90 parts by weight, respectively, two kinds of polycarbonate resins (viscosity average molecular weights 50,000 and 21,500, respectively) having the same repeating unit A laminated photoreceptor was prepared in the same manner as in Example 1 except that 150 parts by weight was used.

(Example 7)
Two kinds of polycarbonate resins (viscosity average molecular weights 38,000 and 21,500, respectively) instead of 90 parts by weight, respectively, two kinds of polycarbonate resins (viscosity average molecular weights 50,000 and 21,500, respectively) having the same repeating unit A laminated photoreceptor was produced in the same manner as in Example 1 except that 160 parts by weight was used.

(Example 8)
In the same manner as in Example 1, an undercoat layer having a thickness of 1 μm was formed on the surface of an aluminum drum-shaped support that is a conductive support.
Next, 8 parts by weight of titanyl phthalocyanine as a charge generation material was mixed with 100 parts by weight of tetrahydrofuran, and dispersed with a paint shaker. Exemplified compound No. 1 was used as a charge transport material in the resulting mixture. 100 parts by weight of one enamine compound, two kinds of polycarbonate resins having the same repeating units as the two kinds of polycarbonate resins of Example 1 (viscosity average molecular weights 50,000 and 21,500, respectively), 90 parts by weight, Exemplified Compound No. manufactured 1 part of the diamine compound, 0.02 part by weight of silicone oil, and 1400 parts by weight of tetrahydrofuran were stirred and mixed to prepare a coating solution for forming a photosensitive layer. This photosensitive layer forming coating solution was applied to the surface of the undercoat layer previously provided by an immersion method and dried at 130 ° C. for 1 hour to form a photosensitive layer having a thickness of 25 μm. In this way, the single-layer type photoreceptor shown in FIG. 4 was produced.

Example 9
Exemplified Compound No. 1 instead of the diamine compound of Ex. A laminated photoreceptor was prepared in the same manner as in Example 1 except that the diamine compound 2 was used.

(Example 10)
Exemplified Compound No. 1 instead of the diamine compound of Ex. A laminated photoreceptor was produced in the same manner as in Example 1 except that the diamine compound No. 4 was used.

(Example 11)
Exemplified Compound No. 1 instead of the diamine compound of Ex. A laminated photoreceptor was prepared in the same manner as in Example 1 except that the diamine compound No. 8 was used.

Example 12
Exemplified Compound No. A laminated photoreceptor was produced in the same manner as in Example 1 except that 0.4 part by weight of the diamine compound 1 was used.

(Example 13)
Exemplified Compound No. A laminated photoreceptor was produced in the same manner as in Example 1 except that 0.5 part by weight of the diamine compound 1 was used.

(Example 14)
Exemplified Compound No. A laminated photoreceptor was prepared in the same manner as in Example 1 except that 10 parts by weight of the diamine compound 1 was used.

(Example 15)
Exemplified Compound No. A laminated photoreceptor was prepared in the same manner as in Example 1 except that 12 parts by weight of the diamine compound 1 was used.

(Comparative Example 1)
Exemplified Compound No. A laminated photoreceptor was produced in the same manner as in Example 1 except that no diamine compound 1 was used.

(Comparative Example 2)
Exemplified compound No. 1 as a charge transport material. A laminated photoreceptor was produced in the same manner as in Example 1 except that an enamine compound represented by the following structural formula was used in place of the enamine compound No. 1.

(Comparative Example 3)
Exemplified compound No. 1 as a charge transport material. A laminated photoreceptor was produced in the same manner as in Example 1 except that an enamine compound represented by the following structural formula was used in place of the enamine compound No. 1.

(Comparative Example 4)
Exemplified compound No. 1 as a charge transport material. A laminated photoreceptor was produced in the same manner as in Example 1 except that a butadiene compound represented by the following structural formula (wherein Et is an ethyl group) was used in place of the enamine compound No. 1.

(Evaluation)
The photoreceptors of Examples 1 to 15 and Comparative Examples 1 to 4 produced as described above were evaluated for (a) potential and (b) durability as follows.

(A) Electric potential evaluation A tandem digital color multi-function machine (prototype) with a process speed of 225 mm / sec, and a photoconductor prototyped under the same conditions for black, yellow (Y), magenta (M) and cyan ( C) for each. Take out the developing tank, and instead set a surface potential meter (Model 344, manufactured by Trek) at the development site, adjust the potential V0 of the black solid document to -600 volts, and then measure the potential VL of the white solid document. The initial sensitivity was evaluated. The single layer type photoreceptor of Example 8 was evaluated by remodeling the polarity of charging and transfer to positive charging.

(B) Durability Evaluation After the evaluation in (a) above, the surface potential meter is taken out, the developing tank is again mounted on the evaluation copying machine, 3 sheets are specified for the monochrome image output mode, and the color image output mode is specified. A total of 40,000 copies of 8000 sets of copy patterns of two 5 sheets were copied using A4 size paper. Then, the halftone image of each color was confirmed and the image quality at the time of repeated use was evaluated. Further, the amount of film loss of the photosensitive layer (thickness difference after copying 40,000 sheets of A4 size paper at the initial stage) was determined to evaluate the printing durability.
The above evaluation results are shown in Table 5.

From the evaluation results in Table 5, the following can be understood.
-According to the evaluation results of Examples 1 and 9 to 11, the image forming apparatus provided with the photoconductor containing the enamine compound of the general formula (1) and the diamine compound of the general formula (I) has the initial sensitivity and the repetitive characteristics. Is excellent.
According to the evaluation results of Examples 1 and 4 to 7, particularly when the ratio T / R between the weight T of the charge transport material and the weight R of the binder resin is 10/12 to 10/30, the photosensitivity Excellent characteristics, stability in repeated use, and mechanical durability.
-According to the evaluation result of Comparative Example 1, when no diamine compound is contained, there is a problem in ozone resistance.
According to the evaluation results of Examples 1 and 8, the image forming apparatus provided with the single-layer photoconductor is inferior in sensitivity characteristics and ozone resistance as compared with the image forming apparatus provided with the laminated photoconductor.
-According to the evaluation results of Comparative Examples 2, 3 and 4, the image forming apparatus provided with the photoconductor containing the charge transport material having an enamine structure other than the enamine compound of the general formula (1) can reduce sensitivity and film thickness. Inferior, there is a problem as a color photoconductor.

1 is a schematic cross-sectional view of a tandem-type color multifunction peripheral equipped with a photoreceptor, showing an example of an image forming apparatus of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a main part of a multilayer photoreceptor in the image forming apparatus of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a main part of a multilayer photoreceptor in the image forming apparatus of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a main part of a single-layer type photoreceptor in the image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1a, 50a Case 2, 2a, 2b, 2c, 2d Developing device (developing means)
3, 3a, 3b, 3c, 3d photoconductor (photoconductor drum)
4, 4a, 4b, 4c, 4d Cleaner unit 5, 5a, 5b, 5c, 5d Charger (charging means)
6, 6a, 6b, 6c, 6d Intermediate transfer roller 7 Intermediate transfer belt (intermediate transfer member)
8 Transfer belt unit (intermediate transfer unit)
8-1 Transfer belt drive roller 8-2 Transfer belt driven roller 8-3 Transfer belt tension mechanism 9 Transfer belt cleaning unit (cleaning unit)
9a Cleaning blade 9b Toner recovery unit 10 Paper feed tray

11 Transfer section (transfer mechanism)
11a Transfer roller 12 Fixing unit 14 Registration roller 15 Paper discharge tray 16 Pickup roller 20, 20a, 20b, 20c, 20d Process printing unit (image forming unit)
Conveyance roller 25 (25-1 to 25-8)
31 Heating roller 32 Pressure roller 40 Control board

50 Exposure unit 51 Laser scanning unit (LSU)
51a Laser irradiation unit 52 Polygon mirror 53a, 53b, 53c, 53d, 54a, 54b, 54c Reflective mirror 55a Cylinder lens 55b Toroidal lens 56a, 56b, 56c, 56d Condensing lens 108 Image forming unit 55 fθ lens 109 Paper feeding unit

201 Conductive Support 202 Charge Generation Material 203 Charge Transport Material 204 Multilayer Type Photosensitive Layer 204 ′ Single Layer Type Photosensitive Layer 205 Charge Generation Layer 206 Charge Transport Layer 208 Undercoat Layer (Intermediate Layer)

Claims (9)

An organic photoconductor, a charging unit for charging the organic photoconductor, an exposure unit for exposing the charged organic photoconductor, and developing an electrostatic latent image formed by the exposure to form a toner image Developing means, transfer means for transferring the developed toner image onto the recording material, fixing means for fixing the transferred toner image on the recording material to form an image, and residual on the organic photoconductor A plurality of image forming units having at least cleaning means for removing and collecting the toner to be collected are provided, and toner images of different colors are sequentially superimposed on the recording material by using different color toners for each of the plurality of image forming units. An image forming apparatus that forms a color image together,
The organic photoreceptor comprises a single layer type photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support made of a conductive material, or a charge generating layer containing a charge generating substance and a charge transporting substance. A layered photosensitive layer in which the charge transporting layer is stacked in this order is laminated, and the charge transporting layer of the single layered photosensitive layer or the layered photosensitive layer is used as a charge transporting substance,
General formula (1):

[Where:
Ar ¹ and Ar ² are the same or different and are an aryl group which may have a substituent or a monovalent heterocyclic residue which may have a substituent, and Ar ¹ and Ar ² bind to them May be bonded to each other through a group of atoms or atomic groups to form a ring structure;
Ar ³ is an aryl group that may have a substituent, a cycloalkyl group that may have a substituent, an alkyl group that may have a substituent, or a monovalent complex that may have a substituent. A ring residue;
Ar ⁴ and Ar ⁵ are the same or different and each represents a hydrogen atom, an aryl group which may have a substituent, an alkyl group which may have a substituent, or a monovalent heterocyclic ring which may have a substituent A residue, Ar ⁴ and Ar ⁵ are not both hydrogen atoms, but may be bonded to each other via an atom or atomic group bonded to them to form a ring structure;
a represents an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a dialkylamino group which may have a substituent, an aryl group which may have a substituent, a halogen atom; Or a hydrogen atom;
m is an integer of 1 to 6, and when m is 2 or more, a plurality of a may be the same or different and are bonded to each other via an atom or an atomic group bonded thereto to form a ring structure. Well;
R ¹ is a hydrogen atom, a halogen atom or an alkyl group which may have a substituent;
R ² , R ³ and R ⁴ are the same or different and are a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or a monovalent which may have a substituent. A heterocyclic residue of
n is an integer of 0 to 3, and when n is 2 or 3, a plurality of R ² and R ³ may be the same or different, and when n is 0, Ar ³ has a substituent. A monovalent heterocyclic residue)
An enamine compound represented by
Formula (I):

[Where:
Ar ⁶ , Ar ⁷ , Ar ⁸ and Ar ⁹ are the same or different, and may be an aryl group which may have a substituent, a cycloalkyl group which may have a substituent, or a hetero which may have a substituent. A monovalent heterocyclic residue optionally having an atom-containing cycloalkyl group or a substituent;
^{Y 1, Y 2, Y 3} , Y 4, Y 5 and Y ⁶ are the same or different, have a good chain alkylene group which may have a substituent;
Z is i) —Ar ¹⁰ —Ar ¹¹ — or ii) —Ar ¹⁰ —W—Ar ¹¹ — (wherein Ar ¹⁰ and Ar ¹¹ are the same or different and may have a substituent) Or a divalent heterocyclic residue which may have a substituent; W is a cycloalkylidene group which may have a substituent, or a chain or branched alkylene group which may have a substituent An oxygen atom or a sulfur atom)
An image forming apparatus comprising: a diamine compound represented by: The enamine compound represented by the general formula (1) is a sub-formula (2):

[Where:
b, c and d are the same or different and each has an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a dialkylamino group which may have a substituent, or a substituent. An aryl group, a halogen atom or a hydrogen atom, which may be
i, j and k are the same or different and are integers of 1 to 5, and when i, k or j is 2 or more, the corresponding plural b, c or d may be the same or different, and May be bonded to each other via an atom or atomic group bonded to the ring to form a ring structure;
Ar ⁴ , Ar ⁵ , a and m have the same meaning as in general formula (1)]
The image forming apparatus according to claim 1, which is represented by: The diamine compound represented by the general formula (I) is a sub-formula (II):

(In the formula, Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ and Ar ¹¹ have the same meanings as those in the general formula (I)).
The image forming apparatus according to claim 1, which is represented by: The diamine compound represented by the sub-formula (II) has the structural formula (III):

The image forming apparatus according to claim 3, which is represented by:   A laminated photosensitive layer in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting material are laminated in this order on a conductive support made of a conductive material is the organic photoreceptor. The image forming apparatus according to claim 1, wherein the image forming apparatus is laminated.   The charge transport layer of the single layer type photosensitive layer or the multilayer type photosensitive layer in the organic photoreceptor contains a binder resin, and the ratio T / R of the weight T of the charge transport material and the weight R of the binder resin is 10/12. The image forming apparatus according to claim 1, wherein the image forming apparatus is 10/30. The content of the diamine compound represented by the general formula (I) in the charge transport layer of the single layer type photosensitive layer or the multilayer type photosensitive layer of the organic photoreceptor is 0.5% by weight to 10% by weight with respect to the charge transport material. The image forming apparatus according to claim 1, which is:   The image forming apparatus according to claim 1, wherein the image forming unit includes an intermediate transfer member.   The image forming apparatus according to claim 1, wherein the charging unit of the image forming unit is a contact charging method.

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