JP2008203766A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in electric properties and capable of effectively suppressing cracking and the generation of black spots attributed to the same, and an image forming apparatus equipped with such an electrophotographic photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor is obtained by disposing a photosensitive layer containing a hole transport agent, a charge generating agent and a binder resin on a substrate. The image forming apparatus uses the same. The hole transport agent is a hydrazone compound represented by formula (1) and value (I/O value) given by dividing an inorganic nature value by an organic nature value in the binder resin is set to ≥0.36. In the formula (1), R<SP>1</SP>-R<SP>4</SP>are each independently a hydrogen atom, a substitutive or unsubstitutive 1-20C alkyl group or the like; Ar<SP>1</SP>is a substitutive or unsubstitutive 6-39C aryl group or the like; and a repeating number n is 0 or 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus. In particular, the present invention relates to an electrophotographic photosensitive member that is excellent in electrical characteristics and can effectively suppress the generation of cracks and black spots resulting therefrom, and an image forming apparatus equipped with such an electrophotographic photosensitive member.

Conventionally, as an electrophotographic photoreceptor used in an image forming apparatus or the like, an organic photoreceptor (OPC) composed of a binder resin, a charge generating agent, a charge transporting agent (a hole transporting agent, an electron transporting agent) and the like has been used. Yes. Such an organic photoreceptor is advantageous in that it is easy to manufacture and has a wide degree of freedom in structural design because it has various options for the photoreceptor material as compared with conventional inorganic photoreceptors.
On the other hand, the charge transport agent used in such an organic photoreceptor needs to have an excellent charge transfer rate so as to impart predetermined electrical characteristics to the electrophotographic photoreceptor.

  Therefore, a hydrazone compound represented by the following general formula (26) is disclosed as a hole transport agent having an excellent charge transfer rate (for example, Patent Document 1).

(In the general formula (26), R ²¹ and R ²² are optionally substituted aryl groups, R ²¹ and R ²² may be bonded directly or via a linking group, R ²³ is a hydrogen atom, halogen An atom, an alkyl group or an optionally substituted phenyl group, R ²⁴ and R ²⁵ are an alkyl group, an aralkyl group or an optionally substituted aryl group, at least one of which is an optionally substituted aryl group .)

JP-A-3-48254 (Claims)

However, although the hole transport agent of Patent Document 1 has an excellent charge transfer rate, it has very high crystallinity, so that the photosensitive layer is easily peeled off from the substrate and cracks are likely to occur. There was a problem.
In particular, when oil components such as sebum derived from a human hand or grease of a driving roller adhere to the surface of the electrophotographic photosensitive member, there is a problem that cracks are likely to occur from the adhesion point. It was. And in the formed image, the problem that it becomes easy to generate | occur | produce a black spot resulting from this crack was seen.
Accordingly, there has been a demand for an electrophotographic photosensitive member that has excellent electrical characteristics and can effectively suppress the occurrence of cracks and black spots caused by the cracks.

Therefore, as a result of intensive studies, the present inventors have used a hydrazone compound having a specific structure as a hole transport agent, and by setting the I / O value in the binder resin within a predetermined range, It has been found that the electrical properties of an electrophotographic photoreceptor can be effectively improved by controlling crystallinity, and the oil resistance of the surface of the photosensitive layer can be improved to effectively suppress the occurrence of cracks. It came to complete.
That is, an object of the present invention is to provide an electrophotographic photoreceptor capable of effectively suppressing the occurrence of cracks and black spots due to the excellent electrical characteristics, and image formation equipped with such an electrophotographic photoreceptor. To provide an apparatus.

  According to the present invention, there is provided an electrophotographic photosensitive member in which a photosensitive layer containing a hole transport agent, a charge generator and a binder resin is provided on a substrate, wherein the hole transport agent is represented by the following general formula (1). Provided is an electrophotographic photosensitive member which is a hydrazone compound represented by the formula and has a value obtained by dividing an inorganic value in a binder resin by an organic value (I / O value) of 0.36 or more. Thus, the above-described problem can be solved.

(In the general formula (1), R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. A substituted or unsubstituted phenoxy group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 1 to 20 carbon atoms, Ar ¹ is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, (It is a substituted or unsubstituted heterocyclic group having 3 to 30 carbon atoms, and the repeating number n is 0 or 1.)

That is, if it is a hydrazone compound represented by the general formula (1), it has an excellent hole transfer rate and sufficiently lowers its crystallinity as compared with conventionally used hydrazone compounds. Therefore, the electric characteristics of the electrophotographic photosensitive member can be effectively improved.
On the other hand, although the hydrazone compound represented by the general formula (1) has been able to relatively reduce its crystallinity, when the oil component adheres to the surface of the photosensitive layer, the crystallinity is reduced. There is a tendency that cracks are likely to occur.
In that respect, in the present invention, since the I / O value in the binder resin is defined within a predetermined range, even in such a case, the occurrence of cracks can be effectively suppressed, The generation of black spots can be prevented.

  In constituting the electrophotographic photoreceptor of the present invention, the hydrazone compound represented by the general formula (1) is preferably a compound represented by the following general formula (2).

(In the general formula (2), Ar ¹ is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heterocyclic group having 3 to 30 carbon atoms, and the repeating number n is 0 or 1 .)

By comprising in this way, the crystallinity of the hole transport agent which has a specific structure can be reduced more.
Therefore, an electrophotographic photoreceptor excellent in electrical characteristics can be produced more easily, and the occurrence of cracks and black spots resulting therefrom can be more effectively suppressed.

In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer is a single layer type, and the content of the hydrazone compound represented by the general formula (1) is set to 100 parts by weight of the binder resin in the photosensitive layer. It is preferable to set it as the value within the range of 10-100 weight part with respect to it.
By comprising in this way, the dispersibility in a single layer type photosensitive layer can be improved, making the charge transport between hole transport agents which have a specific structure efficient.
Therefore, the electrical characteristics can be further improved and the generation of cracks can be further effectively suppressed.

Further, in constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer is a laminate type, and the content of the hydrazone compound represented by the general formula (1) is determined in the binding in the charge transport layer included in the photosensitive layer. It is preferable to set the value within a range of 10 to 500 parts by weight with respect to 100 parts by weight of the resin.
By comprising in this way, the dispersibility in a charge transport layer can be improved, making charge transport between the hole transport agents which have a specific structure more efficient.
Therefore, the electrical characteristics can be further improved and the generation of cracks can be further effectively suppressed.

  In constituting the electrophotographic photosensitive member of the present invention, it is preferable that the binder resin includes a polycarbonate resin represented by the following general formula (3).

(In General Formula (3), R ^{5 to} R ⁸ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. is a group, a is, -O -, - S -, - CO -, - COO -, - (CH 2) 2 -, - SO -, - SO 2 -, - CR 9 R 10 -, - SiR 9 R ^10- or SiR ⁹ R ¹⁰ -O- (R ⁹ and R ¹⁰ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, a substituted or unsubstituted carbon number of 6 -30 aryl group, trifluoromethyl group, or R ⁹ and R ¹⁰ may form a ring and may have a C 1-7 alkyl group as a substituent. And B is a single bond, —O—, or —CO—.)

  With this configuration, it is easy to adjust the I / O value of the binder resin within a predetermined range, and the mechanical strength of the photosensitive layer can be improved. The subscripts p and q indicate the molar ratio.

In constituting the electrophotographic photosensitive member of the present invention, it is preferable to set the viscosity average molecular weight of the binder resin to a value within the range of 10,000 to 60,000.
By comprising in this way, while being able to improve the stability with respect to an oil component more, the compatibility with binder resin and the hole transport agent which has a specific structure can be improved further.

  In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer preferably contains a compound represented by the following general formula (4) as an additive.

(In General Formula (4), R ^{11 to} R ²⁰ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 12 carbon atoms. An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, A cyano group, a nitro group or an amino group, R is a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms, or an organic group containing a nitrogen atom, and r is an integer of 0 to 3).

  By comprising in this way, the effect as a plasticizer which the additive which has this specific structure has, and the characteristic of binder resin which has a predetermined I / O value interact, and it is on the surface of a photosensitive layer. On the other hand, even when the oil component adheres, the generation of cracks can be more effectively suppressed.

According to another aspect of the present invention, there is provided an image forming apparatus including any one of the electrophotographic photosensitive members described above, wherein at least a charging unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member. And an image forming apparatus in which any of the means is disposed in contact with the electrophotographic photosensitive member.
That is, the generation of cracks tends to be promoted by applying a mechanical external force to the photosensitive layer. On the other hand, in the image forming apparatus according to the present invention, even if the charging unit is disposed in contact with the electrophotographic photosensitive member and mechanical external force is applied to the photosensitive layer, the cracking can be effectively performed. Can be suppressed.
Furthermore, since the mounted electrophotographic photosensitive member has excellent electrical characteristics, it is possible to efficiently form a high-quality image in which the generation of black spots is suppressed.

[First Embodiment]
The first embodiment is an electrophotographic photosensitive member in which a photosensitive layer containing a hole transport agent, a charge generating agent, and a binder resin is provided on a substrate, and the hole transport agent as shown in FIG. The hydrazone compound represented by the general formula (1) is used, and a value obtained by dividing the inorganic value in the binder resin by the organic value (I / O value) is 0.36 or more. An electrophotographic photoreceptor.
Hereinafter, the electrophotographic photosensitive member as the first embodiment will be specifically described mainly using a single-layer type electrophotographic photosensitive member as an example.

1. Basic Configuration As shown in FIG. 2A, the single-layer electrophotographic photosensitive member 10 has a single photosensitive layer 14 provided on a substrate 12.
In addition, the photosensitive layer includes a binder resin having a predetermined I / O value, a hole transport agent having a specific structure, and a charge generator, and, if necessary, an electron transport agent and a leveling agent. An additive such as an agent or a silyl group-containing compound can be included.
In addition, as shown in FIG. 2B, a single-layer electrophotographic photosensitive member 10 in which a barrier layer 16 is formed between the substrate 12 and the photosensitive layer 14 in a range that does not inhibit the characteristics of the electrophotographic photosensitive member. '
In addition, the charge transport efficiency between the charge generating agent and the hole transport agent can be further improved by further including an electron transport agent as the charge transport agent.

In addition, various conductive materials can be used as the substrate, such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, and stainless steel. A plastic made by dispersing conductive fine particles such as steel, brass, etc., plastic materials deposited or laminated with the above metals, glass coated with aluminum iodide, tin oxide, indium oxide, etc., or carbon black. Materials and the like.
Further, the shape of the substrate may be any of a sheet shape, a drum shape, or the like according to the structure of the image forming apparatus to be used. The substrate itself has conductivity, or the surface of the substrate has conductivity. If you do.

2. Photosensitive layer (1) Binder resin (1) -1 I / O value The binder resin in the electrophotographic photosensitive member of the present invention has a value (I / O value) obtained by dividing its inorganic value by the organic value (0). The value is set to .36 or more.
The reason for this is that the I / O value of the binder resin is regulated within such a range, and the use of a hole transporting agent having a specific structure described later causes the oil component to adhere to the surface of the photosensitive layer. This is because, even in this case, the occurrence of cracks can be effectively suppressed and the occurrence of black spots in the formed image can be prevented.
That is, by defining the I / O value of the binder resin in such a range and setting the organic value of the binder resin in a relatively low range, even when the oil component adheres to the surface of the photosensitive layer, It is because it can suppress effectively that the state of binder resin changes with this oil component. Therefore, even when the oil component adheres to the surface of the photosensitive layer, it is possible to suppress the monomer component such as the charge transfer agent from being eluted in the oil component and to prevent the occurrence of cracks.
On the other hand, when the I / O value of the binder resin becomes excessively large, it may be difficult to adjust the mechanical strength, conductivity, and the like of the photosensitive layer.
Therefore, the I / O value of the binder resin is more preferably set to a value within the range of 0.36 to 0.4, and further preferably set to a value within the range of 0.363 to 0.39.

Next, the relationship between the I / O value of the binder resin and the occurrence of cracks in the electrophotographic photosensitive member will be described with reference to FIG.
In FIG. 1, the horizontal axis represents the I / O value (−) of the binder resin, and the vertical axis represents the number of cracks occurring in the electrophotographic photosensitive member having a photosensitive layer containing the corresponding binder resin (locations). ) Is shown.
In addition, the hydrazone compound (HTM-1) represented by Formula (8) mentioned later was contained in the photosensitive layer at this time as a hole transport agent which has a specific structure. Further, the configuration of the electrophotographic photosensitive member, the method of measuring the number of crack occurrence points, and the like will be described in detail in later examples.
As can be understood from the characteristic curve, the number of occurrences of cracks decreases as the I / O value of the binder resin increases. More specifically, it can be seen that when the I / O value of the binder resin is a value around 0.35, the number of crack occurrence points is critically reduced. And it turns out that the number of crack generation | occurrence | production locations can be suppressed to 0 almost completely in the range whose I / O value of binder resin is 0.36 or more.
Therefore, under conditions using a hole transporting agent having a specific structure, it is possible to critically suppress the occurrence of cracks by setting the I / O value of the binder resin to a value of 0.36 or more. I understand that I can do it.

Here, the concept of the I / O value will be described in detail. For example, KUMAMOTO PHARMACEUTICAL BULLETIN, No. 1, No. 1-16 (1954); Chemistry, Vol. 11, No. 10, No. 719- 725 (1957); Fragrance Journal, 34, 97-111 (1979); Fragrance Journal, 50, 79-82 (1981); Yes.
That is, one carbon (C) is organic 20, and based on that, the inorganic value and organic value of each polar group are determined as shown in Table 1, and the sum of nonpolar values in each polar group (I value) Then, the sum of organic values (O value) is obtained and the respective ratios are taken as I / O values.
In Table 1, R mainly represents an alkyl group, and φ mainly represents an alkyl group or an aryl group. As can be easily understood from this table, the closer the I / O value is to 0, the more non-polar (hydrophobic and organic) organic compounds are shown, and the higher the I / O value, the more polar (hydrophilic) It can be said that it is an organic compound having a large property and inorganic property.

In addition, such I / O values divide the properties of compounds into organic groups that exhibit covalent bonding and inorganic groups that exhibit ionic bonding, and all organic compounds are named as organic and inorganic axes. It can be said that the index is located at each point on the orthogonal coordinates. That is, the inorganic value is obtained by quantifying the magnitude of the influence of various substituents and bonds of an organic compound on the boiling point based on the hydroxyl group.
Specifically, when the distance between the boiling point curve of the linear alcohol and the boiling point curve of the linear paraffin is about 100 ° C., the influence of one hydroxyl group is set to 100 as a numerical value. Based on this numerical value, the value obtained by quantifying the influence of various substituents or various bonds on the boiling point is the inorganic value of the substituent that the organic compound has. For example, as shown in Table 1, the inorganic value of the —COOH group is 150, and the inorganic value of the double bond is 2. Therefore, the inorganic value of a certain organic compound means the sum of inorganic values such as various substituents and bonds of the organic compound.

Next, a crack generation mechanism will be described.
First, when an oil component adheres to the surface of the photosensitive layer, a monomer component in the photosensitive layer, particularly a charge transport agent composed of a hole transport agent and an electron transport agent, starts to elute into the oil component.
Next, it is considered that a hole is formed in the binder resin of the photosensitive layer at the trace of the elution of the charge transfer agent, and a local stress is generated in the vicinity of the hole to generate a crack. In other words, the occurrence of cracks can be regarded as a combination of two phenomena: a phenomenon of monomer component elution and a phenomenon of stress generation near the vacancies.
When the crack generation mechanism is captured in this way, it is effective by taking predetermined measures for at least one of the elution of the monomer component as the first stage and the stress generation near the vacancy as the second stage. In particular, crack resistance can be obtained.
In the case of the present invention, as described above, the I / O value of the binder resin is regulated within a predetermined range to improve the stability of the binder resin with respect to the oil component, and more effective than the conventional hydrazone compound. The hydrazone compound which suppressed crystallization is used. Therefore, it can be understood that the elution of the monomer component as the first stage described above is suppressed and the generation of cracks is suppressed.
In addition, when the monomer component such as the charge transfer agent is easily crystallized, the dispersibility in the photosensitive layer is lowered, and therefore, the monomer component is likely to elute locally with respect to the oil component, and cracks tend to occur. .

(1) -2 Viscosity average molecular weight Moreover, it is preferable to make the viscosity average molecular weight of binder resin into the value within the range of 10,000-60,000.
The reason for this is that by setting the viscosity average molecular weight of the binder resin to a value within such a range, the stability to the oil component can be further improved, and the hole transport agent having a specific structure with the binder resin This is because the compatibility can be further improved.
That is, when the viscosity average molecular weight of the binder resin is less than 10,000, the oil component remarkably easily infiltrates the surface of the photosensitive layer, and it may be difficult to suppress the occurrence of cracks. It is. On the other hand, when the viscosity average molecular weight of the binder resin exceeds 60,000, the viscosity of the coating solution for the photosensitive layer is remarkably increased, and the compatibility with the hole transporting agent having a specific structure is reduced. This is because it may be difficult to uniformly disperse.
Therefore, the viscosity average molecular weight of the binder resin is more preferably set to a value within the range of 20,000 to 50,000, and further preferably set to a value within the range of 30,000 to 40,000.
In addition, the viscosity average molecular weight of the binder resin can be calculated from [η] = 1.23 × 10 ⁻⁴ M ^{0.83 according} to Schnell's equation by obtaining the intrinsic viscosity [η] with an Ostwald viscometer. [Η] is measured in a binder resin resin solution obtained by dissolving the binder resin at 20 ° C. using a methylene chloride solution as a solvent so that the concentration (C) is 6.0 g / dm ^3. can do.

(1) -3 types It is preferable that the binder resin includes a polycarbonate resin represented by the general formula (3).
This is because the polycarbonate resin represented by the general formula (3) makes it easy to adjust the I / O value of the binder resin within a predetermined range and improves the mechanical strength of the photosensitive layer. Because it can.
That is, if it is a polycarbonate resin represented by the general formula (3), it is easy to adjust its I / O value to a predetermined range, so that the stability to the oil component is effectively improved. In addition, the excellent mechanical strength inherent to the polycarbonate resin can be effectively exhibited.
In addition, p and q in General formula (3) represent the molar ratio of a copolymerization component, for example, when p is 15 and q is 85, it represents that the molar ratio is 15:85. Yes. Moreover, this molar ratio can be measured by, for example, NMR.

(1) -4 Specific example Moreover, as a specific example of polycarbonate resin represented by General formula (3) mentioned above, polycarbonate resin (Resin-1 to 3) represented by following formula (5)-(7). Is mentioned.

(2) Hole transport agent (2) -1 type The electrophotographic photoreceptor of the present invention is characterized in that the hydrazone compound represented by the general formula (1) is used as the hole transport agent.
The reason for this is that the hydrazone compound represented by the general formula (1) has an excellent hole transfer rate, and its crystallinity is sufficiently lowered as compared with conventionally used hydrazone compounds. This is because the electrical characteristics of the electrophotographic photosensitive member can be effectively improved.
On the other hand, although the hydrazone compound represented by the general formula (1) has been able to relatively reduce its crystallinity, when the oil component adheres to the surface of the photosensitive layer, the crystallinity is reduced. There is a tendency that cracks are likely to occur.
In that respect, in the present invention, as described above, since the I / O value in the binder resin is defined within a predetermined range, the occurrence of cracks is effectively suppressed even in such a case. In addition, it is possible to prevent the occurrence of black spots in the formed image.

Moreover, it is preferable that the hydrazone compound represented by General formula (1) is a compound represented by General formula (2).
This is because the crystallinity of the hole transport agent can be further reduced by limiting the hydrazone compound represented by the general formula (1) to such a structure.
Therefore, an electrophotographic photoreceptor excellent in electrical characteristics can be produced more easily, and the generation of cracks and black spots resulting therefrom can be more effectively suppressed.
That is, as shown in the general formula (2), the constituent part including the ethylene or butadiene structure described in the left part of the hydrazone compound and the constituent part including the hydrazone structure described in the right part are respectively a central part. This is because the planarity and symmetry of the molecule are in a suitable state and the crystallinity can be further lowered by being located in the para position of the phenyl group in diphenylamine described in 1.
Further, the spread of the electron cloud is in a suitable state, and the hole transfer speed can be further improved.
Further, by making the hydrogen atom of R ¹ to R ⁴ in the general formula (1), it is because it is possible to further improve the effect described above.

(2) -2 Specific Example In addition, specific examples of the hydrazone compound represented by the general formula (1) include compounds (HTM-1 to 5) represented by the following formulas (8) to (12). Can do.
These compounds all correspond to the compound represented by the general formula (2).

(2) -3 Content Further, the content of the hydrazone compound represented by the general formula (1) is set to a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer. Is preferred.
The reason for this is that by making the content of the hole transport agent having a specific structure a value within such a range, the charge transport between the hole transport agents can be made efficient and the dispersibility in the photosensitive layer can be improved. It is because it can improve.
That is, when the content of the hole transporting agent having a specific structure is less than 10 parts by weight, the sensitivity is lowered, which may cause a practical problem. On the other hand, when the content of the hole transporting agent having a specific structure exceeds 100 parts by weight, the hole transporting agent tends to be excessively crystallized and it is difficult to suppress the occurrence of cracks. In addition, it is sometimes difficult to form an appropriate film as the photosensitive layer.
Therefore, the content of the hole transport agent having a specific structure is more preferably set to a value within the range of 20 to 90 parts by weight, and further preferably set to a value within the range of 30 to 80 parts by weight.

Next, the relationship between the content of the hole transport agent and the occurrence of cracks in the electrophotographic photosensitive member will be described with reference to FIG.
In FIG. 3, the horizontal axis represents the content (parts by weight) of the hole transport agent with respect to 100 parts by weight of the binder resin, and the vertical axis represents an electrophotographic photoreceptor having a photosensitive layer containing the hole transport agent. The characteristic curve which took the number (location) of the crack generation | occurrence | production in is shown.
Here, the characteristic curve A is a compound (HTM-1) represented by the formula (8) which is a hydrazone compound represented by the general formula (1), and the characteristic curve B is an amine compound represented by the following formula (14) Is a characteristic curve when the compound (HTM-7) represented by) is used as a hole transport agent.
The marker C is a marker when a compound (HTM-6) represented by the following formula (13), which is a conventional hydrazone compound, is used as a hole transport agent.
As the binder resin in the photosensitive layer at this time, a polycarbonate resin (Resin-1) represented by the formula (5) was used as the binder resin having a predetermined I / O value. Further, the configuration of the electrophotographic photosensitive member, the method of measuring the number of crack occurrence points, and the like will be described in detail in later examples. Moreover, the maximum value of the number of crack occurrence locations is 10 locations.

First, as can be understood from the characteristic curve A, when the hydrazone compound represented by the general formula (1) is used as the hole transport agent, the number of cracks generated is small as the content increases. However, if the content of the hole transport agent is in the range of 100 parts by weight or less, it can be seen that the number of cracks can be stably suppressed to 1 or less.
On the other hand, as understood from the characteristic curve B, the amine compound (HTM-7) represented by the formula (14) which is a compound other than the hydrazone compound represented by the general formula (1) is used as the hole transport agent. If it is, it can be seen that the number of cracks increases as the content increases. More specifically, it can be seen that when the content of the hole transfer agent is 60 parts by weight, the number of cracks generated increases to nine.
Moreover, as understood from the marker C, the hydrazone compound (HTM-6) represented by the formula (13) which is another compound other than the hydrazone compound represented by the general formula (1) as a hole transport agent is used. When used, when the content exceeded 30 parts by weight, crystals were precipitated in the photosensitive layer and on the surface of the photosensitive layer, and the number of cracks could not be measured.
As described above, in a hole transporting agent other than a hole transporting agent having a specific structure, a binding having a predetermined I / O value is caused by a difference in crystallinity, solubility in an oil component, and the like. It can be seen that even when used in combination with a resin, it is difficult to exert an effective interaction.
In addition, as shown in the characteristic curve A, if it is a hole transport agent which has a specific structure, generation | occurrence | production of a crack can be suppressed effectively irrespective of the change of the content. However, when the content of the hole transport agent having a specific structure is excessive or too small, depending on the kind of the binder resin having a predetermined I / O value used together, those In some cases, it may be difficult to exhibit an interaction with the binder resin, and problems such as insufficient sensitivity and crystallization may occur. Therefore, the content of the hole transport agent having a specific structure is preferably set to a value within the range of 10 to 100 parts by weight.

(3) Electron Transfer Agent (3) -1 Type As the electron transfer agent used in the present invention, a conventionally known electron transfer agent can be used.
For example, in addition to diphenoquinone derivatives, pyrene derivatives, benzoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, Nitroantharaquinone derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, dibromoanhydride maleic One kind of acid or a combination of two or more kinds may be mentioned.

(3) -2 Specific Examples Specific examples of these electron transfer agents include compounds (ETM-1 to ETM-3) represented by the following formulas (15) to (17).

(3) -3 Content The content of the electron transport agent is preferably set to a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the electron transport agent added is less than 10 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, when the added amount of the electron transport agent exceeds 100 parts by weight, the electron transport agent is likely to be crystallized, and an appropriate film as a photoreceptor may not be formed.
Therefore, it is more preferable to set the addition amount of the electron transfer agent to a value within the range of 20 to 80 parts by weight.

In addition, when determining the addition amount of an electron transport agent, it is preferable to consider the addition amount of a hole transport agent. More specifically, the addition ratio (total ETM / total HTM) of the electron transport agent (total ETM) is a value within the range of 0.25 to 1.3 with respect to the hole transport agent (total HTM). It is preferable to do.
This is because if the ratio of all ETMs / all HTMs is outside this range, the sensitivity is lowered, which may cause practical problems.
Therefore, it is more preferable that the ratio of the total ETM / total HTM is set to a value within the range of 0.5 to 1.25.

(4) Charge Generator (4) -1 Type As the charge generator used in the electrophotographic photosensitive member of the present invention, a conventionally known charge generator can be used.
For example, phthalocyanine pigments, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyranium pigments, ansan Organic photoconductors such as throne pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, and inorganic photoconductors such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon Or a mixture of two or more of them.

(4) -2 Specific Example Further, among these charge generators, it is more preferable to use phthalocyanine pigments (CGM-A to D) represented by the following formulas (18) to (21). preferable.

(4) -3 Content The content of the charge generator is preferably set to a value within the range of 0.2 to 40 parts by weight with respect to 100 parts by weight of the binder resin.
The reason for this is that when the content of the charge generating agent is less than 0.2 parts by weight, the effect of increasing the quantum yield becomes insufficient, and the sensitivity, electrical characteristics, stability, etc. of the electrophotographic photoreceptor are improved. It is because it becomes impossible. On the other hand, when the content of the charge generating agent exceeds 40 parts by weight, the effect of increasing the extinction coefficient for light having a wavelength in the red region, near infrared region, or infrared region in visible light becomes insufficient. This is because the sensitivity characteristics, electrical characteristics, stability, and the like of the photoconductor may not be improved.
Therefore, the content of the charge generating agent is more preferably set to a value within the range of 0.5 to 20 parts by weight.

(5) Additive (5) -1 Type In addition, the photosensitive layer preferably contains a compound represented by the general formula (4) as an additive.
The reason for this is that by adding an additive having such a specific structure to the photosensitive layer, the additive has an effect as a plasticizer and a characteristic of a binder resin having a predetermined I / O value. This is because the occurrence of cracks can be more effectively suppressed even when the oil component adheres to the surface of the photosensitive layer due to the interaction.
That is, if the additive has such a specific structure, even if a monomer component such as a charge transfer agent is eluted in the oil component and a hole is formed in the photosensitive layer, This is because, due to the effect as a plasticizer, the stress generated in the vicinity of the pores can be effectively relieved and the generation of cracks can be suppressed.

(5) -2 Specific Example Further, as the additive having such a specific structure, specifically, compounds (P-1 to P-3) represented by the following formulas (22) to (24) may be used. preferable.

(5) -3 Content The content of the additive having a specific structure is preferably set to a value in the range of 1.5 to 14 parts by weight with respect to the binder resin of the photosensitive layer.
The reason for this is that when the content is less than 1.5 parts by weight, the stress relaxation action as described above cannot be sufficiently exhibited, and crack generation cannot be sufficiently prevented. On the other hand, when the content exceeds 14 parts by weight, the glass transition point of the photosensitive layer is excessively lowered, and the wear resistance may be lowered. Moreover, it is because the dispersibility in binder resin falls and the case where it crystallizes is seen.
Therefore, the content of the additive having a specific structure is more preferably 2 to 12 parts by weight and further preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin of the photosensitive layer.

  In addition, as other additives, as long as they do not adversely affect the electrophotographic characteristics, various conventionally known additives, for example, antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, Softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photosensitive layer, a known sensitizer such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

(6) Thickness The thickness of the photosensitive layer is preferably set to a value in the range of 5 to 100 μm.
This is because if the thickness of the photosensitive layer is less than 5 μm, it may be difficult to form the photosensitive layer uniformly or the mechanical strength may be reduced. On the other hand, when the thickness of the photosensitive layer exceeds 100 μm, the photosensitive layer may be easily peeled off from the substrate.
Accordingly, the thickness of the photosensitive layer is more preferably set to a value within the range of 10 to 50 μm, and further preferably set to a value within the range of 15 to 45 μm.

(7) Manufacturing method Although it does not restrict | limit especially as a manufacturing method of a single layer type electrophotographic photoreceptor, it can implement in the following procedures.
First, a coating solution is prepared by adding a charge generating agent, a charge transporting agent, a binder resin, an additive and the like to a solvent. The coating solution thus obtained is applied onto a conductive substrate (aluminum tube) using a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, or a roller coating method. Apply.
Then, for example, it is dried with hot air at 100 ° C. for 40 minutes to obtain a single layer type electrophotographic photosensitive member having a photosensitive layer having a predetermined thickness.
In addition, as a solvent for making a dispersion liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane Ethers such as 1,4-dioxane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethyl Examples include tilformamide and dimethyl sulfoxide. These solvents are used alone or in admixture of two or more. At this time, in order to improve the dispersibility of the charge generating agent and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be further contained.

It is also preferable to form an intermediate layer on the substrate before forming this photosensitive layer.
In forming this intermediate layer, a binder resin and, if necessary, an additive (organic fine powder or inorganic fine powder) together with an appropriate dispersion medium, a known method such as a roll mill, ball mill, attritor, paint shaker, ultrasonic wave A coating solution is prepared by dispersing and mixing using a disperser or the like, and this is applied by a known means such as a blade method, a dipping method, or a spray method, and subjected to heat treatment to form an intermediate layer.
In addition, the additive is in a range where precipitation during production does not become a problem, and various additives (organic fine powder or inorganic fine powder are used for the purpose of preventing the occurrence of interference fringes by causing light scattering. ) Can be added in small amounts.
Next, the obtained coating solution is applied to a support substrate (aluminum base tube) according to a known production method, such as dip coating, spray coating, bead coating, blade coating, roller coating, etc. It can apply | coat using the apply | coating method.
Then, it is preferable to perform the process of drying the coating liquid on a base | substrate at the temperature of 20-200 degreeC for 5 minutes-2 hours.

  In addition, as a solvent for making such a coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane. Aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. These solvents are used alone or in admixture of two or more.

(8) Multilayer Electrophotographic Photoreceptor In constituting the electrophotographic photoreceptor of the present invention, the photosensitive layer comprises a charge generating layer 24 containing a charge generating agent, a charge transporting agent and a binder as shown in FIG. It is also preferable that the photosensitive layer 20 is a laminated type comprising a charge transport layer 22 containing a resin.
In the multilayer electrophotographic photoreceptor 20, a charge generation layer 24 containing a charge generation agent is formed on the substrate 12 by means of vapor deposition or coating, and then a charge transport agent and a charge transport agent are formed on the charge generation layer 24. The charge transport layer 22 can be formed by applying a coating solution containing a binder resin and drying it.
Contrary to the structure described above, as shown in FIG. 4B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon. However, since the charge generation layer 24 is much thinner than the charge transport layer 22, the charge transport layer 22 is protected on the charge generation layer 24 as shown in FIG. It is more preferable to form
It is also preferable to form the intermediate layer 25 on the substrate as in the case of the single layer type photoreceptor.
In addition, when such a laminated type photosensitive layer is employed, there are advantages that options for photosensitive materials such as a charge generating agent and a charge transport agent are widened, and the degree of freedom in structural design can be improved.

  In addition, the positive or negative charge type of the multilayer electrophotographic photosensitive member is selected depending on the order of forming the charge generation layer and the charge transport layer and the type of charge transport agent used in the charge transport layer. For example, when a charge generation layer is provided on a substrate, a charge transport layer is provided thereon, and a hole transport agent having a specific structure is used as the charge transport agent of the charge transport layer, negatively charged electrons It becomes a photographic photoreceptor. In this case, the charge generation layer may contain an electron transport agent.

The charge generation layer forming coating solution and the charge transport layer forming coating solution are, for example, a predetermined component such as a charge generating agent, a charge transporting agent, a binder resin, a dispersion medium, a roll mill, a ball mill, an attritor, a paint. It can be prepared by dispersing and mixing using a shaker, an ultrasonic disperser or the like.
In the laminated photosensitive layer 20, the thickness of the photosensitive layer (charge generation layer and charge transport layer) is not particularly limited, but the charge generation layer is preferably set to a value in the range of 0.01 to 5 μm. More preferably, the value is in the range of 0.1 to 3 μm. On the other hand, the charge transport layer is preferably set to a value in the range of 2 to 100 μm, and more preferably set to a value in the range of 5 to 50 μm.

Moreover, it is preferable to make content of the hole transport agent which has a specific structure into the value within the range of 10-500 weight part with respect to 100 weight part of binder resin in a charge transport layer.
The reason for this is that by making the content of the hole transport agent having a specific structure within such a range, the charge transport between the hole transport agents is made more efficient and the dispersibility in the charge transport layer is improved. It is because it can be made.
That is, when the content of the hole transporting agent having a specific structure is less than 10 parts by weight, the sensitivity is lowered, which may cause a practical problem. On the other hand, when the content of the hole transport agent having such a specific structure exceeds 500 parts by weight, the hole transport agent is easily crystallized excessively, and it is difficult to suppress the occurrence of cracks. In addition, it is sometimes difficult to form an appropriate film as the photosensitive layer.
Therefore, the content of the hole transport agent having a specific structure is more preferably set to a value within the range of 25 to 200 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport layer.
When the electron transport agent is further contained in the charge transport layer, the content of the electron transport agent is preferably 5 to 200 parts by weight and more preferably 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin. preferable.
The content of the charge generation agent in the charge generation layer is preferably set to a value within the range of 5 to 1000 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer, and within the range of 30 to 500 parts by weight. It is more preferable to set the value within the range.

[Second Embodiment]
The second embodiment is an image forming apparatus equipped with the electrophotographic photosensitive member as the first embodiment, and at least a charging unit, a developing unit, and a transfer unit are arranged around the electrophotographic photosensitive member. In addition, the image forming apparatus is characterized in that any means is disposed in contact with the electrophotographic photosensitive member.
Hereinafter, the image forming apparatus as the second embodiment will be described focusing on the points different from the contents described in the first embodiment.

The image forming apparatus of the second embodiment can be configured as a copying machine 30 as shown in FIG. 5, for example. The copying machine 30 includes an image forming unit 31, a paper discharge unit 32, an image reading unit 33, and a document feeding unit 34. The image forming unit 31 further includes an image forming unit 31a and a paper feeding unit 31b. In the illustrated example, the document feeding unit 34 includes a document placing tray 34a, a document feeding mechanism 34b, and a document discharge tray 34c, and the document placed on the document placing tray 34a. Is fed to the image reading position P by the document feeding mechanism 34b and then discharged to the document discharge tray 34c.
Then, when the original is sent to the original reading position P, the image reading unit 33 reads the image on the original using the light from the light source 33a. That is, an image signal corresponding to the image on the document is formed using an optical element 33b such as a CCD.
On the other hand, recording sheets (hereinafter simply referred to as “sheets”) S stacked on the sheet feeding unit 31b are sent one by one to the image forming unit 31a. The image forming unit 31a is provided with a photoconductive drum 41 as an image carrier. Further, around the photoconductive drum 41, a charger 42, an exposure unit 43, a developing unit 44, and a transfer roller. 45 is arranged along the rotation direction of the photosensitive drum 41.

Among these components, the photosensitive drum 41 is rotationally driven in the direction indicated by the solid line arrow in the drawing, and the surface thereof is uniformly charged by the charger 42. Thereafter, an exposure process is performed on the photosensitive drum 41 by the exposure device 43 based on the above-described image signal, and an electrostatic latent image is formed on the surface of the photosensitive drum 41.
Based on the electrostatic latent image, the developing unit 44 attaches toner and develops it, thereby forming a toner image on the surface of the photosensitive drum 41. The toner image is transferred as a transfer image onto the sheet S conveyed to the nip portion between the photosensitive drum 41 and the transfer roller 45. Next, the sheet S to which the transferred image is transferred is conveyed to the fixing unit 47 and a fixing process is performed.
The photosensitive drum 41 is characterized by using the electrophotographic photosensitive member described in the first embodiment. Further, at least one of the charging unit, the developing unit, and the transfer unit is in contact with the photosensitive drum 41. For example, if it is a transfer means, a form like the transfer roller 45 corresponds to this.

  Further, the sheet S after fixing is sent to the paper discharge unit 32. However, when performing post-processing (for example, stapling processing), the paper S is sent to the intermediate tray 32a and then post-processed. Is done. Thereafter, the sheet S is discharged to a discharge tray portion (not shown) provided on the side surface of the image forming apparatus. On the other hand, when no post-processing is performed, the sheet S is discharged to a discharge tray 32b provided below the intermediate tray 32a. The intermediate tray 32a and the paper discharge tray 32b are configured as a so-called in-body paper discharge unit.

By the way, the generation of cracks tends to be promoted by applying a mechanical external force to the photosensitive layer. On the other hand, in the case of the image forming apparatus according to the present invention, since the mounted electrophotographic photosensitive member has excellent crack resistance, the charging means and the like are disposed in contact with the electrophotographic photosensitive member, and the photosensitive layer However, even when a mechanical external force is applied, the occurrence of cracks can be effectively suppressed.
Furthermore, since the mounted electrophotographic photosensitive member has excellent electrical characteristics, it is possible to efficiently form a high-quality image in which the generation of black spots is suppressed.

[Example 1]
1. Production of electrophotographic photoreceptor In a container, 3 parts by weight of X-type metal-free phthalocyanine (CGM-A) represented by the formula (18) as a charge generating agent and formula (8) as a hole transporting agent are represented. 60 parts by weight of the compound (HTM-1), 30 parts by weight of the compound (ETM-1) represented by the formula (15) as the electron transport agent, and formula (5) as the binder resin 100 parts by weight of a polycarbonate resin (Resin-1) having a viscosity average molecular weight of 30,000 and 800 parts by weight of tetrahydrofuran as a solvent were accommodated.
Subsequently, it was mixed and dispersed in a ball mill for 50 hours to prepare a coating solution for a single-layer type photosensitive layer. The obtained coating solution was applied on a base (aluminum tube) having a length of 254 mm and a diameter of 30 mm by dip coating, and dried with hot air under conditions of 100 ° C. for 40 minutes, and a single layer having a thickness of 25 μm. A single-layer electrophotographic photosensitive member having a photosensitive layer was obtained.

2. Evaluation of electrophotographic photoreceptor (1) Evaluation of generation of cracks Evaluation of generation of cracks in the obtained electrophotographic photoreceptor was performed.
That is, ten places on the surface of the obtained electrophotographic photosensitive member were directly touched by hands to attach fat derived from a human body and left for 3 days. Subsequently, the generation | occurrence | production condition of the crack in each adhesion location was confirmed using the optical microscope, and it evaluated along the following reference | standard. The obtained results are shown in Table 2.
◯: There are no cracks at 0 places.
(Triangle | delta): The crack generation location is 1-3 places.
X: The crack generation location is 4 or more locations.

(2) Evaluation of black spot generation Moreover, black spot generation | occurrence | production in the obtained electrophotographic photoreceptor was evaluated.
That is, the obtained electrophotographic photosensitive member is mounted on a printer (manufactured by Kyocera Mita, DP-560), and continuously printed 5000 sheets of A4 paper (Fuji Xerox high-quality PPC paper) at 40 ° C. and 90% Rh environmental conditions. did. Then, after leaving for 6 hours, a blank A4 paper document was printed, and the number of black spots generated on the A4 paper was counted and evaluated according to the following criteria. The obtained results are shown in Table 2.
○: Less than 20 black spots occur per A4 paper.
(Triangle | delta): Generation | occurrence | production of black spots per A4 paper is 20 or more and less than 200.
X: The number of black spots generated per A4 paper is 200 or more.

(3) Evaluation of electrical characteristics The sensitivity of the obtained electrophotographic photosensitive member was measured under the following conditions.
That is, using a drum sensitivity tester (produced by GENTEC Co., Ltd.), the surface potential of the electrophotographic photosensitive member is charged to +700 V, and is extracted from white light of a halogen lamp using a bandpass filter. Monochromatic light (half-width 20 nm, light intensity 0.6 μJ / cm ² ) was irradiated to the electrophotographic photoreceptor surface for 50 msec. Next, the surface potential at the time when 0.35 seconds had elapsed from the start of exposure was measured as the bright potential (V). The obtained results are shown in Table 2.

[Example 2]
In Example 2, the electrophotographic photosensitive member was the same as in Example 1 except that the binder resin used when producing the electrophotographic photosensitive member was a polycarbonate resin (Resin-2) represented by the formula (6). The body was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 3]
In Example 3, the electrophotographic photosensitive member was the same as in Example 1 except that the binder resin used in producing the electrophotographic photosensitive member was a polycarbonate resin (Resin-3) represented by the formula (7). The body was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 4]
In Example 4, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was a hydrazone compound (HTM-2) represented by the formula (9). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 5]
In Example 5, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was a hydrazone compound (HTM-3) represented by the formula (10). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 6]
In Example 6, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was a hydrazone compound (HTM-4) represented by the formula (11). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 7]
In Example 7, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was a hydrazone compound (HTM-5) represented by the formula (12). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Example 8]
In Example 8, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the electron transporting agent used in producing the electrophotographic photosensitive member was a compound (ETM-2) represented by the formula (16). And evaluated. The obtained results are shown in Table 2.

[Example 9]
In Example 9, the electrophotographic photosensitive member was the same as in Example 1 except that the electron transporting agent used in producing the electrophotographic photosensitive member was a compound (ETM-3) represented by the formula (17). And evaluated. The obtained results are shown in Table 2.

[Example 10]
In Example 10, the electrophotographic photoreceptor was produced and evaluated in the same manner as in Example 1 except that the content of the hole transport agent used in producing the electrophotographic photoreceptor was 30 parts by weight. The obtained results are shown in Table 2.

[Example 11]
In Example 11, the electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the content of the hole transporting agent used in producing the electrophotographic photosensitive member was 90 parts by weight. The obtained results are shown in Table 2.

[Comparative Example 1]
In Comparative Example 1, electrophotography was performed in the same manner as in Example 1 except that the binder resin used in producing the electrophotographic photosensitive member was polycarbonate resin (Resin-4) represented by the following formula (25). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Comparative Example 2]
In Comparative Example 2, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was an amine compound (HTM-7) represented by the formula (14). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2.

[Comparative Example 3]
In Comparative Example 3, an electrophotographic photoreceptor was produced and evaluated in the same manner as in Comparative Example 1 except that the content of the hole transport agent used in producing the electrophotographic photoreceptor was 30 parts by weight. The obtained results are shown in Table 2.

[Comparative Example 4]
In Comparative Example 4, an electrophotographic photoreceptor was produced and evaluated in the same manner as in Comparative Example 1 except that the content of the hole transport agent used in producing the electrophotographic photoreceptor was 90 parts by weight. The obtained results are shown in Table 2.

[Comparative Example 5]
In Comparative Example 5, electrophotography was performed in the same manner as in Example 1 except that the hole transporting agent used in producing the electrophotographic photosensitive member was a hydrazone compound (HTM-6) represented by the formula (13). A photoconductor was manufactured and evaluated. The obtained results are shown in Table 2. The occurrence of cracks could not be evaluated because crystals were precipitated in the photosensitive layer and on the surface of the photosensitive layer.

[Comparative Example 6]
In Comparative Example 6, an electrophotographic photoreceptor was produced and evaluated in the same manner as Comparative Example 5 except that the content of the hole transporting agent used in producing the electrophotographic photoreceptor was 30 parts by weight. The obtained results are shown in Table 2.

As described above in detail, according to the present invention, a hydrazone compound having a specific structure is used as the hole transport agent, and the I / O value in the binder resin is set within a predetermined range, whereby the hydrazone compound is used. By controlling the crystallinity of the electrophotographic photosensitive member, the electrical characteristics of the electrophotographic photosensitive member can be effectively improved, and the oil resistance of the surface of the photosensitive layer can be improved to effectively suppress the occurrence of cracks. became.
Therefore, the electrophotographic photosensitive member of the present invention and an image forming apparatus using the same are expected to contribute to extending the life and speed of various image forming apparatuses such as copying machines and printers.

It is a figure provided in order to demonstrate the relationship between the I / O value of binder resin, and generation | occurrence | production of a crack. (A)-(b) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a single layer type electrophotographic photoreceptor. It is a figure provided in order to demonstrate the relationship between content of a hole transport agent, and generation | occurrence | production of a crack. (A)-(b) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a laminated type electrophotographic photoreceptor. FIG. 3 is a diagram for explaining an image forming apparatus including an electrophotographic photosensitive member.

Explanation of symbols

10: Single layer type photoreceptor 12: Conductive substrate 14: Photosensitive layer 16: Barrier layer 20: Multilayer type photoreceptor 22: Charge transport layer 24: Charge generation layer 25: Intermediate layer 30: Copying machine 31: Image forming unit 31a : Image forming unit 31 b: Paper feeding unit 32: Paper discharge unit 33: Image reading unit 33 a: Light source 33 b: Optical element 34: Document feeding unit 34 a: Document loading tray 34 b: Document feeding mechanism 34 c: Document discharge tray 41 : Photosensitive drum 42: Charger 43: Exposure source 44: Developer 45: Transfer roller

Claims (8)

An electrophotographic photosensitive member provided with a photosensitive layer containing a hole transport agent, a charge generator and a binder resin on a substrate,
The hole transport agent is a hydrazone compound represented by the following general formula (1), and a value obtained by dividing an inorganic value in the binder resin by an organic value (I / O value) is 0.36 or more. An electrophotographic photosensitive member characterized by having a value.

(In the general formula (1), R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. A substituted or unsubstituted phenoxy group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 1 to 20 carbon atoms, Ar ¹ is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, (It is a substituted or unsubstituted heterocyclic group having 3 to 30 carbon atoms, and the repeating number n is 0 or 1.) The electrophotographic photoreceptor according to claim 1, wherein the hydrazone compound represented by the general formula (1) is a compound represented by the following general formula (2).

(In the general formula (2), Ar ¹ is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heterocyclic group having 3 to 30 carbon atoms, and the repeating number n is 0 or 1 .)   The photosensitive layer is a single layer type, and the content of the hydrazone compound represented by the general formula (1) is within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin in the photosensitive layer. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is a value.   The photosensitive layer is a laminate type, and the content of the hydrazone compound represented by the general formula (1) is 10 to 500 weights with respect to 100 parts by weight of the binder resin in the charge transport layer included in the photosensitive layer. The electrophotographic photosensitive member according to claim 1, wherein the value is within a range of part. The electrophotographic photosensitive member according to claim 1, wherein the binder resin includes a polycarbonate resin represented by the following general formula (3).

(In General Formula (3), R ^{5 to} R ⁸ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. is a group, a is, -O -, - S -, - CO -, - COO -, - (CH 2) 2 -, - SO -, - SO 2 -, - CR 9 R 10 -, - SiR 9 R ^10- or SiR ⁹ R ¹⁰ -O- (R ⁹ and R ¹⁰ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, a substituted or unsubstituted carbon number of 6 -30 aryl group, trifluoromethyl group, or R ⁹ and R ¹⁰ may form a ring and may have a C 1-7 alkyl group as a substituent. And B is a single bond, —O—, or —CO—.)   The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein the binder resin has a viscosity average molecular weight of 10,000 to 60,000. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a compound represented by the following general formula (4) as an additive.

(In General Formula (4), R ^{11 to} R ²⁰ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 12 carbon atoms. An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, A cyano group, a nitro group or an amino group, R is a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms, or an organic group containing a nitrogen atom, and r is an integer of 0 to 3). An image forming apparatus equipped with the electrophotographic photosensitive member according to any one of claims 1 to 7,
At least a charging unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member, and any of the units is disposed in contact with the electrophotographic photosensitive member. .