JP5391687B2 - Electrophotographic photosensitive member, method for manufacturing electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, a method for manufacturing an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

An electrophotographic image forming apparatus generally has the following configuration and process.
That is, the surface of the electrophotographic photosensitive member is charged to a predetermined polarity and potential by a charging unit, and the surface of the electrophotographic photosensitive member after charging is selectively neutralized by image exposure to form an electrostatic latent image, The toner is attached to the electrostatic latent image by the developing means, whereby the latent image is developed as a toner image, and the toner image is transferred to a transfer medium by the transfer means, and discharged as an image formed product. .

In recent years, an electrophotographic photosensitive member has an advantage that high-speed and high printing quality can be obtained, so that it is increasingly used in fields such as a copying machine and a laser beam printer.
As electrophotographic photoreceptors used in these image forming apparatuses, conventional electrophotographic photoreceptors (inorganic photoreceptors) using inorganic photoconductive materials such as selenium, selenium-tellurium alloys, selenium-arsenic alloys, and cadmium sulfide are known. In recent years, organic photoreceptors (organic photoreceptors) using organic photoconductive materials, which are inexpensive and have excellent advantages in terms of manufacturability and disposal, have come to dominate.

On the other hand, as a charging method, a corona charging method using a corona discharger has been conventionally used. In recent years, a contact charging method having advantages such as low ozone and low power has been put into practical use and has been actively used. In this contact charging method, a conductive member as a charging member is brought into contact with or close to the surface of the photosensitive member, and a voltage is applied to the charging member to charge the surface of the photosensitive member. In addition, as a method of applying to the charging member, there are a direct current method in which only a direct current voltage is applied and an alternating current superposition method in which an alternating current voltage is superimposed on the direct current voltage. This contact charging system has the advantages that the apparatus can be miniaturized and that gas such as ozone is less generated.
Further, as a transfer method, a method of directly transferring to paper has been the mainstream, but since the degree of freedom of paper to be transferred is widened, a method of transferring using an intermediate transfer member has been actively used in recent years. .

On the other hand, it has been proposed to improve the strength by providing a protective layer on the surface of the electrophotographic photosensitive member.
The following materials have been proposed as a material system for forming the protective layer.
That is, for example, Patent Document 1 includes a conductive powder dispersed in a phenol resin, Patent Document 2 includes an organic-inorganic hybrid material, and Patent Document 3 includes an alcohol-soluble charge transport material and a phenol resin. Are disclosed respectively.
Patent Document 4 discloses a cured film of an alkyl etherated benzoguanamine / formaldehyde resin and an electron-accepting carboxylic acid or an electron-accepting polycarboxylic acid anhydride, and Patent Document 5 discloses a benzoguanamine resin containing iodine, A cured film doped with an organic sulfonic acid compound or ferric chloride is disclosed in Patent Document 6 as a cured film of a specific additive and a phenol resin, a melamine resin, a benzoguanamine resin, a siloxane resin, or a urethane resin. Is disclosed as a protective layer.

In recent years, a protective layer made of an acrylic material has attracted attention. For example, Patent Document 7 discloses a film obtained by curing a liquid containing a photocurable acrylic monomer, and Patent Document 8 discloses a monomer having a carbon-carbon double bond and a charge transfer having a carbon-carbon double bond. A film formed by reacting a carbon-carbon double bond of the monomer and a carbon-carbon double bond of the charge transfer material with a mixture of a material and a binder resin by heat or light energy is disclosed in Patent Literature 9 discloses a film made of a compound obtained by polymerizing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule as a protective layer.
Since these acrylic materials are strongly affected by curing conditions, curing atmospheres, etc., for example, Patent Document 10 discloses a film formed by heating after irradiation with radiation in a vacuum or in an inert gas. Patent Document 11 discloses a film cured by heating in an inert gas.
Furthermore, for example, Patent Documents 8 and 12 disclose that the charge transport material itself is acrylic-modified to be crosslinkable and a reactive monomer having no charge transport property is added to improve the film strength. ing.

Furthermore, the following things are proposed as a protective layer by a reaction material and a cured film.
For example, Patent Document 13 discloses a protective layer containing a compound obtained by modifying the charge transport material itself into a polyfunctional trifunctional or higher polyfunctional polymer. Patent Document 14 discloses a technique in which a polymer of a charge transport material having a chain polymerizable functional group is used for a protective layer. In addition, Patent Document 15 discloses a trifunctional or higher functional radical polymerizable monomer having no charge transporting skeleton, a monofunctional radical polymerizable compound having a charge transporting skeleton, and a reactive silicone having a radical polymerizable functional group. In an electrophotographic photosensitive member to which a coating liquid containing a compound is applied and cured, in order to proceed the curing reaction uniformly, after heating at a relatively low temperature of less than 100 ° C., the reaction is further completed by heating to 100 ° C. or more. The method is also disclosed to be effective.
Japanese Patent No. 3287678 Japanese Patent Laid-Open No. 12-019749 JP 2002-82469 A Japanese Patent Laid-Open No. 62-251757 Japanese Patent Laid-Open No. 7-146564 JP 2006-84711 A JP-A-5-40360 JP-A-5-216249 JP 2000-206715 A Japanese Patent Laid-Open No. 2004-12986 Japanese Patent Laid-Open No. 7-72640 JP 2004-302450 A JP 2000-206717 A JP 2001-175016 A JP 2005-115353 A

An object of the present invention is to provide an electrophotographic photosensitive member having a high adhesion strength with a lower layer, having an outermost surface layer excellent in surface properties, and having stable electrical characteristics and image characteristics even after repeated use over a long period of time, The present invention also provides a method for producing the electrophotographic photosensitive member.
Another object of the present invention is to provide a process cartridge and an image forming apparatus provided with the electrophotographic photosensitive member.

The above problem is solved by the following means. That is,
The invention according to claim 1 has at least a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer has a charge transporting skeleton and an acryloyl group or methacryloyl group in the same molecule. And a composition containing at least one thermal polymerization initiator (b) including two thermal polymerization initiators having a difference in 10-hour half-life temperature of 20 ° C. or higher. An electrophotographic photosensitive member comprising a cured film of a product.

  The invention according to claim 2 is the electrophotographic photoreceptor according to claim 1, wherein the cured film is obtained by curing the composition with heat.

  The invention according to claim 3 is a monomer or oligomer (c) in which the composition does not have a charge transporting property that reacts with the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to claim 1, further comprising:

  The invention according to claim 4 is characterized in that the composition further contains a polymer (d) that does not react with the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to any one of claims 1 to 3.

  The invention according to claim 5 is characterized in that the composition further contains a polymer (e) that reacts with the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to claim 1.

  The invention according to claim 6 is a compound in which the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule has a triphenylamine skeleton and four or more methacryloyl groups in the same molecule ( The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is a ′).

  The invention according to claim 7 is characterized in that the compound (a ′) having a triphenylamine skeleton and four or more methacryloyl groups in the same molecule is a compound represented by the following general formula (A): The electrophotographic photosensitive member according to claim 6.

In the general formula (A), Ar ^{1 to} Ar ⁴ each independently represent a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted arylene group. , D represents — (CH ₂ ) _d — (O—CH ₂ —CH ₂ ) _e —O—CO—C (CH ₃ ) ═CH ₂ , and c1 to c5 are each independently 0, 1 or 2 , K represents 0 or 1, d represents an integer of 1 to 5, e represents 0 or 1, and the total number of D is 4 or more.

The invention according to claim 8 includes at least one compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule, and two types of heat having a difference in 10-hour half-life temperature of 20 ° C. or more. A coating solution comprising a composition containing two or more thermal polymerization initiators (b) containing a polymerization initiator is applied to the surface to be coated to form a coating film, and then the coating film is cured by heat. And a method for producing an electrophotographic photoreceptor, comprising a step of obtaining an outermost surface layer.

The invention according to claim 9 is an electrophotographic photosensitive member according to any one of claims 1 to 7 , charging means for charging the electrophotographic photosensitive member, and a static formed on the electrophotographic photosensitive member. At least one means selected from the group consisting of developing means for developing an electrostatic latent image with toner and toner removing means for removing toner remaining on the surface of the electrophotographic photosensitive member, and is attached to and detached from the image forming apparatus It is a process cartridge characterized by being free.

The invention according to claim 1 0, and an electrophotographic photosensitive member according to any one of claims 1 to 7, a charging means for charging the electrophotographic photoreceptor, the electrophotographic photosensitive member charged Electrostatic latent image means for forming an electrostatic latent image, developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive member with toner to form a toner image, and transferring the toner image to a transfer target And an image forming apparatus.

  According to the first aspect of the present invention, an electron having an outermost surface layer having high adhesive strength with a lower layer and excellent surface properties, and having stable electrical characteristics and image characteristics even after repeated use over a long period of time. A photographic photoreceptor is provided.

  According to the second aspect of the present invention, an electrophotographic photosensitive member having better surface properties is provided.

  According to the invention of claim 3, an electrophotographic photosensitive member having an outermost surface layer having higher mechanical strength is provided.

  According to the fourth aspect of the present invention, there is provided an electrophotographic photosensitive member having an outermost surface layer that is superior in surface properties and excellent in gas barrier properties.

  According to the fifth aspect of the present invention, there is provided an electrophotographic photosensitive member having an outermost surface layer that is more excellent in surface properties and excellent in gas barrier properties while maintaining high mechanical strength.

  According to the sixth aspect of the present invention, an electrophotographic photosensitive member having an outermost surface layer with high mechanical strength and further improved electrical characteristics is provided.

  According to the seventh aspect of the present invention, there is provided an electrophotographic photosensitive member having an outermost surface layer having high mechanical strength and further improved electrical characteristics.

According to the eighth aspect of the present invention, an electron having an outermost surface layer having high adhesive strength with a lower layer and excellent surface properties, and having stable electrical characteristics and image characteristics even after repeated use over a long period of time. A method for producing a photographic photoreceptor is provided.

According to the ninth aspect of the present invention, there is provided a process cartridge capable of obtaining a stable image over a long period of time.

According to the invention of claim 1 0, the image forming apparatus stable image for a long time can be obtained are provided.

[Electrophotographic photoconductor]
The electrophotographic photoreceptor according to the exemplary embodiment includes at least a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer includes a charge transporting skeleton and an acryloyl group in the same molecule. Or at least one compound (a) having a methacryloyl group, and two or more thermal polymerization initiators (b) including two thermal polymerization initiators having a difference in 10-hour half-life temperature of 20 ° C. or more , An electrophotographic photosensitive member comprising a cured film of the contained composition.
Hereinafter, the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule will be referred to as a specific charge transport material (a) as appropriate.

In the electrophotographic photoreceptor according to the exemplary embodiment, the above-described configuration has the outermost surface layer having high adhesion strength with the lower layer and excellent surface properties, and electrical characteristics and image characteristics even after repeated use over a long period of time. Is maintained stably.
Although it is not necessarily clear about the mechanism which has said effect, it estimates as follows.

That is, the cured film constituting the outermost surface layer as in this embodiment is formed by, for example, heat curing. When a heating furnace is used for this heat curing, the substrate of the electrophotographic photosensitive member has a large heat capacity. because of its coating film formed by using a composition containing a specific charge transporting materials (a) and two or more thermal polymerization initiator (b) is not only reaches the set temperature instantly The set temperature is gradually reached from room temperature. Therefore, by using two or more thermal polymerization initiators (b) in addition to the specific charge transport material (a), radicals can be generated gradually by adjusting the amount and activity expression temperature. It is considered that a cured film with little residual strain can be obtained by an effect similar to the stepwise overheating described in Patent Document 15.
On the other hand, when one kind of thermal polymerization initiator is used, radicals are generated all at once in a relatively narrow temperature range, so that the reaction proceeds at once, and it is considered that a cured film is easily left with residual strain. .
As described above, since a cured film with little residual strain can be obtained, the surface layer having the cured film has high adhesive strength with the lower layer and has excellent surface properties. As a result, the electrophotographic photoreceptor having such an outermost surface layer can stably maintain electrical characteristics and image characteristics even after repeated use over a long period of time.

As described above, the electrophotographic photoreceptor according to the exemplary embodiment includes a cured film of a composition containing at least one specific charge transport material (a) and two or more thermal polymerization initiators (b). Although it has an outermost surface layer, the outermost surface layer only needs to form the uppermost surface of the electrophotographic photosensitive member itself, and is provided as a layer that functions as a protective layer or a layer that functions as a charge transport layer. .
When the outermost surface layer is a layer that functions as a protective layer, a photosensitive layer comprising a charge transport layer and a charge generation layer, or a single-layer type photosensitive layer (charge generation / charge transport layer) is formed under the protective layer. ).

In the case where the outermost surface layer functions as a protective layer, the photosensitive layer and the outermost surface layer have a protective layer on the conductive substrate, and the protective layer includes at least one specific charge transport material (a) and The form comprised by the cured film of the composition containing 2 or more types of thermal-polymerization initiators (b) is mentioned.
On the other hand, when the outermost surface layer is a layer that functions as a charge transport layer, it has a charge generation layer and a charge transport layer as the outermost surface layer on the conductive substrate, and the charge transport layer is a specific charge transport material (a And a cured film of a composition containing at least one thermal polymerization initiator (b).

Hereinafter, the electrophotographic photoreceptor according to the exemplary embodiment in the case where the outermost surface layer functions as a protective layer will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the electrophotographic photoreceptor according to the embodiment. 2 to 3 are schematic sectional views showing electrophotographic photosensitive members according to other embodiments.

  An electrophotographic photoreceptor 7A shown in FIG. 1 is a so-called function-separated photoreceptor (or laminated photoreceptor), and an undercoat layer 1 is provided on a conductive substrate 4, on which a charge generation layer 2 and a charge are formed. The transport layer 3 and the protective layer 5 have a structure formed sequentially. In the electrophotographic photoreceptor 7 </ b> A, the charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer.

  The electrophotographic photoreceptor 7B shown in FIG. 2 is a function-separated type photoreceptor in which the functions are separated into the charge generation layer 2 and the charge transport layer 3 like the electrophotographic photoreceptor 7A shown in FIG. Further, the electrophotographic photoreceptor 7C shown in FIG. 3 contains the charge generation material and the charge transport material in the same layer (single layer type photosensitive layer 6 (charge generation / charge transport layer)).

In the electrophotographic photoreceptor 7B shown in FIG. 2, a structure in which an undercoat layer 1 is provided on a conductive substrate 4, and a charge transport layer 3, a charge generation layer 2, and a protective layer 5 are sequentially formed thereon. It is what has. In the electrophotographic photoreceptor 7B, a photosensitive layer is constituted by the charge transport layer 3 and the charge generation layer 2.
Further, the electrophotographic photoreceptor 7C shown in FIG. 3 has a structure in which the undercoat layer 1 is provided on the conductive substrate 4, and the single-layer type photosensitive layer 6 and the protective layer 5 are sequentially formed thereon. It is.

In the electrophotographic photoreceptors 7A to 7C shown in FIGS. 1 to 3, the protective layer 5 is the outermost surface layer disposed on the side farthest from the conductive substrate 2, and the outermost surface layer is The predetermined configuration is adopted.
In the electrophotographic photoreceptor shown in FIGS. 1 to 3, the undercoat layer 1 may or may not be provided.

  Hereinafter, each element will be described based on the electrophotographic photosensitive member 7A shown in FIG. 1 as a representative example.

<Protective layer>
First, the protective layer 5 that is the outermost surface layer in the electrophotographic photoreceptor 7A will be described.
The protective layer 5 is the outermost surface layer in the electrophotographic photoreceptor 7A, and is a cured film of a composition containing at least one specific charge transport material (a) and two or more thermal polymerization initiators (b). Consists of.
First, the specific charge transport material (a) will be described.

(Specific charge transport material (a))
The specific charge transporting material (a) used for the protective layer (outermost surface layer) 5 is a compound having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule, and must satisfy this structural condition. Anything can be used.
Here, the charge transporting skeleton in the specific charge transporting material (a) is a triarylamine compound, a benzidine compound, a hydrazone compound as the charge transporting skeleton in the reactive charge transporting material (a). A structure derived from a nitrogen-containing hole-transporting compound such as a compound having a structure conjugated with a nitrogen atom corresponds to the charge-transporting skeleton.

In particular, the specific charge transport material (a) is desirably a compound having a methacryloyl group.
The reason is not clear, but is presumed as follows.
Usually, a highly reactive acrylic group is often used for the curing reaction, but when a highly reactive acryloyl group is used as a substituent in a bulky charge transporting skeleton, a heterogeneous curing reaction tends to occur. It is thought that a micro (or macro) sea-island structure is likely to be formed. Such a sea-island structure is not particularly problematic outside of the electronic field, but when used as an electrophotographic photosensitive member, unevenness and wrinkles of the outermost surface layer are likely to occur, and portions with different charge transport properties are macroscopic. As a result, problems such as image unevenness occur. In addition, it is thought that formation of such a sea-island structure becomes particularly remarkable when a plurality of functional groups are attached to one charge transporting skeleton.
Therefore, since the formation of the sea-island structure as described above can be suppressed by using the specific charge transport material (a) having a methacryloyl group, the composition containing the specific charge transport material (a) in this desirable mode. It is presumed that the electrophotographic photoreceptor having the outermost surface layer composed of the cured film can obtain electric characteristics and image characteristics more stably.

  In the specific charge transport material (a), it is desirable that the structure has one or more carbon atoms between the charge transporting skeleton and the acryloyl group or methacryloyl group. In other words, the specific charge transport material (a) is preferably a mode in which a carbon chain containing one or more carbon atoms is connected as a linking group between the charge transport skeleton and the acryloyl group or methacryloyl group. In particular, it is the most desirable embodiment that the linking group is an alkylene group.

The reason why the above aspect is desirable is not necessarily clear, but can be considered as follows.
That is, if the electron-withdrawing methacryloyl group is too close to the charge transporting skeleton, the charge density of the charge transporting skeleton decreases and the ionization potential increases, which makes it difficult for carrier injection from the lower layer to proceed smoothly. There is. In addition, when a radical polymerizable substituent such as a methacryloyl group is polymerized, if the radical generated at the time of polymerization is easily transferred to the charge transporting skeleton, the generated radical deteriorates the charge transport function. For this reason, it is considered that the electrical characteristics are deteriorated. Furthermore, regarding the mechanical strength of the outermost surface layer, if the bulk charge transporting skeleton and the polymerization site (acryloyl group or methacryloyl group) are close and rigid, the polymerization sites will not move easily and the probability of reaction will decrease. There seems to be a fear.
From these facts, a structure in which a flexible carbon chain is interposed between an acryloyl group and an acryloyl group or a methacryloyl group is desirable.

  Furthermore, the specific charge transport material (a) may be a compound (a ′) having a structure having a triphenylamine skeleton and three or more, more preferably four or more methacryloyl groups in the same molecule. This is a desirable mode. By setting it as this aspect, stability of the compound at the time of a synthesis | combination can be ensured, and it has the outstanding advantage that it can be produced on an industrial scale. Further, by adopting this embodiment, the outermost surface layer having a high crosslink density and sufficient mechanical strength can be formed, so that it is not always necessary to add a polyfunctional monomer having no charge transporting property. The thickness of the outermost surface layer can be increased without causing deterioration of electrical characteristics due to the addition of the monomer. As a result, the electrophotographic photoreceptor having the outermost surface layer has a long life and can withstand long-term use.

  In the present embodiment, the specific charge transport material (a) is preferably a compound represented by the following general formula (A) because of excellent charge transport properties.

In the general formula (A), Ar ^{1 to} Ar ⁴ each independently represent a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted arylene group. , D represents — (CH ₂ ) _d — (O—CH ₂ —CH ₂ ) _e —O—CO—C (CH ₃ ) ═CH ₂ , and c1 to c5 are each independently 0, 1 or 2 , K represents 0 or 1, d represents an integer of 1 to 5, e represents 0 or 1, and the total number of D is 4 or more.

In the general formula (A), Ar ^{1 to} Ar ⁴ each independently represent a substituted or unsubstituted aryl group. Ar ^{1 to} Ar ⁴ may be the same or different.
Here, as a substituent in the substituted aryl group, carbon other than D: — (CH ₂ ) _d — (O—CH ₂ —CH ₂ ) _e —O—CO—C (CH ₃ ) ═CH ₂ Examples thereof include an alkyl group or an alkoxy group having 1 to 4 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.
Ar ^{1 to} Ar ⁴ are preferably any of the following formulas (1) to (7). In addition, the following formulas (1) to (7) collectively indicate “— (D) _C1 ” to “— (D) _C4 ” that can be connected to each of Ar ^{1 to} Ar ^4. _C ".

In the above formulas (1) to (7), R ¹ is substituted with a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Represents one selected from the group consisting of a phenyl group, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, wherein R ^{2 to} R ⁴ are each independently a hydrogen atom, 1 to 4 carbon atoms. The following alkyl groups, alkoxy groups having 1 to 4 carbon atoms, phenyl groups substituted with alkoxy groups having 1 to 4 carbon atoms, unsubstituted phenyl groups, aralkyl groups having 7 to 10 carbon atoms, and halogen atoms 1 represents one selected from the group consisting of: Ar represents a substituted or unsubstituted arylene group; D represents — (CH ₂ ) _d — (O—CH ₂ —CH ₂ ) _e —O—CO—C (CH ₃ ) represents CH ₂ , C represents 1 or 2, s represents 0 or 1, and t represents an integer of 0 or more and 3 or less.

  Here, as Ar in Formula (7), what is represented by following Structural formula (8) or (9) is desirable.

In the above formulas (8) and (9), R ⁵ and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or 1 to 4 carbon atoms. It represents one selected from the group consisting of a phenyl group substituted with the following alkoxy group, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t ′ is 0 or more and 3 or less, respectively. Represents an integer.

  In the formula (7), Z ′ represents a divalent organic linking group, and is preferably represented by any one of the following formulas (10) to (17). S represents 0 or 1 respectively.

In the above formulas (10) to (17), R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or 1 to 4 carbon atoms. 1 represents one selected from the group consisting of a phenyl group substituted with the following alkoxy group, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, W represents a divalent group, q and r each independently represents an integer of 1 to 10, and t ″ represents an integer of 0 to 3, respectively.

  W in the formulas (16) to (17) is preferably any one of divalent groups represented by the following (18) to (26). However, in formula (25), u represents an integer of 0 or more and 3 or less.

In general formula (A), Ar ⁵ is a substituted or unsubstituted aryl group when k is 0, and this aryl group is the same as the aryl group exemplified in the description of Ar ^{1 to} Ar ^4. Can be mentioned. Ar ⁵ is a substituted or unsubstituted arylene group when k is 1, and as this arylene group, a hydrogen atom at a predetermined position is selected from the aryl groups exemplified in the description of Ar ^{1 to} Ar ^4. An arylene group excluded.

  Specific examples (compounds A-1 to A-21) of the compound represented by the general formula (A) are shown below. In addition, the compound shown by general formula (A) is not limited at all by these.

The compound represented by the general formula (A) is synthesized as follows.
That is, in the compound represented by the general formula (A), the precursor alcohol is condensed with the corresponding methacrylic acid or methacrylic acid halide, or when the precursor alcohol has a benzyl alcohol structure, It can be synthesized by dehydrating etherification with a methacrylic acid derivative having a hydroxyl group such as hydroxyethyl methacrylate.

  The synthesis route of compound A-4 and compound A-17 used in this embodiment is shown below as an example.

  As described above, the compound (a ′) having a triphenylamine skeleton and four or more methacryloyl groups in the same molecule has been described as a desirable embodiment of the specific charge transport material (a). The following compounds (hereinafter referred to as “other reactive charge transport materials (a ″)” as appropriate) can be used as the specific charge transport materials (a).

  That is, as the other reactive charge transport material (a ″), a compound (a ″) obtained by introducing an acryloyl group or a methacryloyl group into a known charge transport material can be used. Known charge transport materials include, for example, triarylamine compounds, benzidine compounds, arylalkane compounds listed as hole transport compounds among charge transport materials constituting the charge transport layer 3 described later. Aryl substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and the like. More specifically, as other reactive charge transport materials (a ″), the compound described in Patent Document 8, the compound described in Patent Document 9, the compound described in Patent Document 10, and the Patent Document 11, the compound described in Patent Document 12, the compound described in Patent Document 13, the compound described in Patent Document 14, and the compound described in Patent Document 15.

Among these, as the other reactive charge transport material (a ″), a compound having a triphenylamine skeleton and 1 to 3 acrylic groups or methacryloyl groups in the same molecule is desirable. In particular, the general formula (A) D represents — (CH ₂ ) _f — (O—CH ₂ —CH ₂ ) _g —O—CO—C (R) ═CH ₂ , f represents an integer of 0 to 5, and g represents 0 or 1 and R represents a hydrogen atom or a methyl group, and a compound in which the total number of D is 1 or more and 3 or less is preferable. Among them, a compound in which f is an integer of 1 to 5 and R is a methyl group desirable.
Specific examples of other reactive charge transport materials (a ″) are shown below.

  Specific examples of compounds having a triphenylamine skeleton and one acrylic group or methacryloyl group in the same molecule, which is one of other reactive charge transport materials (a ″), include compounds I-1 to I— 12, but is not limited thereto.

  Specific examples of compounds having a triphenylamine skeleton and two acrylic groups or methacryloyl groups in the same molecule, which is one of the other reactive charge transport materials (a ″), include compounds II-1 to II- 19, but is not limited thereto.

  Specific examples of compounds having a triphenylamine skeleton and three acrylic groups or methacryloyl groups in the same molecule, which is one of the other reactive charge transport materials (a ″), include compounds III-1 to III- 11 is not limited thereto.

The total content of the specific charge transport material (a) is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass with respect to the composition used when forming the protective layer (outermost surface layer) 5. % Or more and 100% by mass or less, more desirably 50% by mass or more and 100% by mass or less.
By setting it as this range, it is excellent in the electrical property of a cured film (outermost surface layer), and thickening of a cured film is attained.

  In the specific charge transport material (a), the content of the compound having a charge transporting skeleton and three or more acryloyl groups or acryloyl groups is used when the protective layer (outermost surface layer) 5 is formed. 5 mass% or more is desirable with respect to a composition, More desirably, it is 10 mass% or more, More desirably, it is 15 mass% or more.

In this embodiment, as the specific charge transport material (a), a compound having a charge transporting skeleton and four or more acryloyl groups or acryloyl groups, a charge transporting skeleton and one or more and two or less acryloyl groups or It is desirable to use in combination with a compound having an acryloyl group. In particular, it is desirable to use a compound represented by the general formula (A) in combination with a compound having a triphenylamine skeleton and at least one acrylic group or methacryloyl group in the same molecule.
In this embodiment, the specific charge transporting material (a) is crosslinked without reducing the abundance of the charge transporting skeleton as compared with a case where all of the specific charge transporting material (a) is a compound having four or more methacryloyl groups (reactive groups). Since the density can be reduced, the strength of the cured film (outermost surface layer) can be adjusted while maintaining the electrical characteristics.

  Specific charge transport when a compound having a charge transporting skeleton and four or more acryloyl groups or acryloyl groups and a compound having a charge transporting skeleton and one or more and three or less acryloyl groups or acryloyl groups are used in combination In the total amount of the material (a), the compound having a charge transporting skeleton and four or more acryloyl groups or acryloyl groups is preferably contained in an amount of 5% by mass or more, more preferably 10% by mass or more. More preferably, it is contained at 15% by mass or more.

(Other charge transport materials)
In addition to the specific charge transport material (a) described above, the cured film constituting the protective layer (outermost surface layer) 5 was a known charge transport material having no reactive group, and was used as necessary. It may be a cured film. Here, the reactive group means a radical polymerizable unsaturated bond.
A known charge transport material having no reactive group does not have a reactive group that does not bear charge transport. For example, when this known charge transport material is used in combination, the concentration of the charge transport component is substantially increased. The electrical properties of the cured film (outermost surface layer) can be further improved. Moreover, the well-known charge transport material which does not have a reactive group can contribute to adjustment of the intensity | strength of a cured film (outermost surface layer). Furthermore, since the specific charge transporting material (a) has a charge transporting skeleton, it is excellent in compatibility with known charge transporting materials having no reactive group, and therefore, the conventional charge transporting material having no reactive group. Doping of the material is performed, and it is possible to further improve the electrical characteristics.

  As a known charge transport material having no reactive group, for example, those listed as charge transport materials constituting the charge transport layer 3 described later are used. Among these, those having a triphenylamine skeleton are desirable from the viewpoint of mobility and compatibility.

  The known charge transport material having no reactive group is preferably used in an amount of 2% by mass to 50% by mass, more preferably 5% by mass to 45% by mass with respect to the solid content in the coating solution. More preferably, it is 10 mass% or more and 40 mass% or less.

(Two or more thermal polymerization initiators (b))
In forming the protective layer (outermost surface layer) 5, a composition containing two or more thermal polymerization initiators (b) in addition to the specific charge transport material (a) described above is used.
As this thermal polymerization initiator, a known thermal polymerization initiator can be used. Specifically, it is desirable to use a commercially available thermal polymerization initiator as shown below. Some of the following thermal polymerization initiators are listed with a 10-hour half-life temperature.

That is, examples of commercially available thermal polymerization initiators include, for example, V-30 (10 hour half-life temperature: 104 ° C.), V-40 (same as 88 ° C.), V-59 (same as 67 ° C.), V- 601 (same: 66 ° C), V-65 (same: 51 ° C), V-70 (same: 30 ° C), VF-096 (same: 96 ° C), Vam-110 (same: 111 ° C), Vam- 111 (same as above: 111 ° C.) (manufactured by Wako Pure Chemical Industries, Ltd.), OT _AZO- 15 (same as 61 ° C.), OT _AZO- 30, AIBM (same as 65 ° C.), AMBN (same as 67 ° C.), ADVN (Same as above: 52 ° C.), ACVA (same as above: 68 ° C.) (above, manufactured by Otsuka Chemical Co., Ltd.) and the like.
Pertetra A, Perhexa HC, Perhexa C, Perhexa V, Perhexa 22, Perhexa MC, Perbutyl H, Park Mill H, Park Mill P, Permenta H, Per Octa H, Perbutyl C, Perbutyl D, Perhexyl D, Parroyl IB, Parroyl 355, Parroyl L, Parroyl SA, Niper BW, Niper BMT-K40 / M, Parroyl IPP, Parroyl NPP, Parroyl TCP, Parroyl OPP, Parroyl SBP, Park Mill ND, Parocta ND, Perhexyl ND, Perbutyl ND, Perbutyl NHP, Perhexyl PV, Perbutyl PV, perhexa 250, perocta O, perhexyl O, perbutyl O, perbutyl L, perbutyl 355, perhexyl I, perbutyl I, perbutyl E, per Kisa 25Z, Perbutyl A, hexyl to par Z, Perbutyl ZT, Perbutyl Z (manufactured by NOF Chemical Co.),

  Kayaketal AM-C55, Trigonox 36-C75, Laurox, Parkardox L-W75, Parkardox CH-50L, Trigonox TMBH, Kayacumen H, Kayabutyl H-70, Percadox BC-FF, Kayahexa AD, Parkadox 14, Kayabutyl C, Kayabutyl D, Kayahexa YD-E85, Parkadox 12-XL25, Parkadox 12-EB20, Trigonox 22-N70, Trigonox 22-70E, Trigonox D-T50, Trigonox 423-C70, Kaya Ester CND-C70, Kaya Ester CND- W50, Trigonox 23-C70, Trigonox 23-W50N, Trigonox 257-C70, Kaya ester P-70, Kaya ester TMPO-70, Trigo 121, Kaya Ester O, Kaya Ester HTP-65W, Kaya Ester AN, Trigonox 42, Trigonox F-C50, Kaya Butyl B, Kaya Carbon EH-C70, Kaya Carbon EH-W 60, Kaya Carbon I-20, Kaya Carbon BIC-75, Trigonox 117 , Kayalen 6-70 (above, manufactured by Kayaku Akzo),

  Lupelox LP (same as above: 64 ° C), Lupelox 610 (same as above: 37 ° C), Lupelox 188 (same as above: 38 ° C), Lupelox 844 (same as above: 44 ° C), Lupelox 259 (same as above: 46 ° C), Lupelox 10 (same as above: 48 ° C), Lupelox 701 (same as 53 ° C), Lupelox 11 (same as 58 ° C), Lupelox 26 (same as 77 ° C), Lupelox 80 (same as 82 ° C), Lupelox 7 (same as 102 ° C), Lupelox 270 (same as above: 102 ° C.), Lupelox P (same as above: 104 ° C.), Lupelox 546 (same as above: 46 ° C.), Lupelox 554 (same as above: 55 ° C.), Lupelox 575 (same as above: 75 ° C.) ° C), Lupelox 555 (same as above: 100 ° C), Lupelox 570 (same as above: 96 ° C), Pelox TAP (same: 100 ° C), Lupelox TBIC (same: 99 ° C), Lupelox TBEC (same: 100 ° C), Lupelox JW (same: 100 ° C), Lupelox TAIC (same: 96 ° C), Lupelox TAEC (same: 99 ° C), Lupelox DC (same as 117 ° C), Lupelox 101 (same as 120 ° C), Lupelox F (same as 116 ° C), Lupelox DI (same as 129 ° C), Lupelox 130 (same as 131 ° C), Lupelox 220 (same as above: 107 ° C.), Lupelox 230 (same as above: 109 ° C.), Lupelox 233 (same as above: 114 ° C.), Lupelox 531 (same as above: 93 ° C.) (above, manufactured by Arkema Yoshitomi) and the like.

Even if these thermal polymerization initiators are used alone, the curing reaction proceeds, but in this embodiment, two or more kinds are used to obtain a cured film with little residual strain.
In particular, the present invention, among the two or more thermal polymerization initiator, a 10-hour half-life lowest ones and the best Monono difference alignment saw set Ru der 20 ° C. or higher, uniform cured film can be obtained .
In addition, the thermal polymerization initiator is preferably combined with a 10-hour half-life temperature of 40 ° C. or higher and 120 ° C. or lower, in terms of the pot life of the coating solution and the progress of the curing reaction, It is more desirable to combine with things.

The use ratio of the thermal polymerization initiators having different 10-hour half-life temperatures of 20 ° C. or more can be arbitrarily set, but the total of the lowest and highest 10-hour half-life temperatures is 30% of the total thermal polymerization initiator amount. The content is preferably at least mass%, more preferably at least 40 mass%, and even more preferably at least 50 mass%. By setting within this range, a cured film having excellent uniformity, low residual strain, and excellent adhesion to the lower layer can be obtained.
Further, in the 10-hour half-life temperature of 20 ° C. or more different thermal polymerization initiator, the ratio of the lowest ones of the mass of the 10-hour half-life temperature (L) and highest Monono mass (H), L: H = 2: The ratio is desirably 8 or more and 9: 1 or less, more preferably L: H = 3: 7 or more and 9: 1 or less, and further desirably L: H = 4: 6 or more and 9: 1 or less. In this way, by setting the mass of the lowest 10-hour half-life temperature to a certain level or more, the curing reaction can proceed more mildly, excellent uniformity, less residual strain, and excellent adhesion It can be assumed that a film is easily obtained.

  The total content of the thermal polymerization initiator is desirably 0.2% by mass or more and 10% by mass or less, and more desirably 0.5% by mass with respect to the total solid content in the composition containing the specific charge transport material (a). It is in the range of not less than 8% by mass and more preferably not less than 0.7% by mass and not more than 5% by mass.

The composition containing the specific charge transport material (a) and two or more thermal polymerization initiators (b) according to this embodiment contains a reactive compound (c) that does not have charge transport properties. Also good. By using the specific charge transporting material (c), the protective layer 5 (outermost surface layer) having sufficient electrical properties and mechanical strength can be obtained. Therefore, the reactive compound having no charge transporting property is obtained. You may adjust the mechanical strength of the protective layer 5 (outermost surface layer) by using (c) together.
Here, “having no charge transporting property” means that carrier transport is not observed by the Time of Flight method.
Such reactive compounds include monofunctional or polyfunctional polymerizable monomers, oligomers, and polymers, such as acrylate or methacrylate monomers, oligomers, and polymers.

  Specifically, as monofunctional monomers, for example, isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol Acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, 2-hydroxy acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, methoxypolyethylene glycol acrylate, methoxypolyethylene glycol Methacrylate, phenoxy polyethylene glycol Acrylate, phenoxy polyethylene glycol methacrylate, hydroxyethyl o- phenylphenol acrylate, o- phenylphenol glycidyl ether acrylate, and the like.

  Examples of the bifunctional monomer, oligomer, and polymer include diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6- Examples include hexanediol di (meth) acrylate.

  Examples of the trifunctional monomer, oligomer, and polymer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and aliphatic tri (meth) acrylate.

  Examples of the tetrafunctional monomer, oligomer, and polymer include pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and aliphatic tetra (meth) acrylate.

  In addition, as penta- or higher functional monomers, oligomers and polymers, for example, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc., as well as polyester skeleton, urethane skeleton, and phosphazene skeleton (meth) An acrylate etc. are mentioned.

The monomers, oligomers, and polymers described above can be used alone or as a mixture of two or more.
In addition, the monomers, oligomers, and polymers described above are based on the total amount of the compound having charge transportability (the above-mentioned specific charge transport material and other charge transport materials) in the composition containing the specific charge transport material. It is used in an amount of 100% by mass or less, desirably 50% by mass or less, more desirably 30% by mass or less.

In addition, a composition containing a specific charge transport material (a) and two or more thermal polymerization initiators (b) has a cured film (outermost surface layer) for the purpose of particle dispersibility and viscosity control. discharge gas resistance, mechanical strength, scratch resistance, torque reduction, abrasion loss control, the purpose of the pot life extension, polymers that react with the specific charge transporting materials (a) (e), or unreacted polymer (d ) Can also be mixed.

  The protective layer 5 (outermost surface layer) made of a cured film of a composition containing the specific charge transport material (a) and two or more kinds of thermal polymerization initiators (b) has sufficient electrical characteristics and mechanical strength. Since it is ensured, various polymers may be used in combination as the binder resin. By using these polymers, the viscosity of the composition is improved, and the protective layer 5 (outermost surface layer) excellent in surface properties is formed, and the gas barrier property for preventing gas from being mixed in the outermost surface is improved. In addition, it can contribute to improvement of adhesion with the lower layer.

The polymer ( e ) that reacts with the specific charge transport material (a) may be a polymer having an unsaturated double bond capable of radical polymerization as a reactive group. In addition to the acrylate or methacrylate polymer described above, for example, JP-A-5-216249, paragraphs [0026] to [0059], JP-A-5-323630, paragraphs [0027] to [0029], JP-A-11-52603, paragraphs [0089] to [0100]. ] Disclosed in paragraphs [0107] to [0128] of JP-A No. 2000-264961.
The polymer ( d ) that does not react with the specific charge transport material (a) may be any polymer that does not contain an unsaturated double bond capable of radical polymerization, and specifically includes polycarbonate resin, polyester resin, Known materials such as arylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin and the like can be mentioned.
These polymers are 100 masses with respect to the total amount of the compound having charge transportability (the specific charge transport material (a) and other charge transport materials described above) in the composition containing the specific charge transport material (a). % Or less, desirably 50 mass% or less, more desirably 30 mass% or less.

In addition, the composition containing the specific charge transport material (a) and two or more thermal polymerization initiators (b) further adjusts the film formability, flexibility, lubricity, and adhesion. For the purpose of, for example, a coupling agent, a hard coat agent, and a fluorine-containing compound may be added. Specifically, various silane coupling agents and commercially available silicone hard coat agents are used as these additives.
As the silane coupling agent, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane and the like are used.
Commercially available hard coat agents include KP-85, X-40-9740, X-8239 (manufactured by Shin-Etsu Silicone), AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning). Etc.) are used.
Further, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- (hepta) for imparting water repellency and the like. Fluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyl Fluorine-containing compounds such as triethoxysilane may be added. Furthermore, a reactive fluorine-containing compound disclosed in JP 2001-166510 A or the like may be mixed.
Although the silane coupling agent is used in an arbitrary amount, the amount of the fluorine-containing compound is desirably 0.25 times or less by mass with respect to the compound not containing fluorine. If this amount is exceeded, there may be a problem with the film formability of the crosslinked film.

  In addition, the protective layer (outermost surface layer) 5 has discharge gas resistance, mechanical strength, scratch resistance, torque reduction, wear amount control, extended pot life, and particle dispersibility and viscosity control. A resin that dissolves in alcohol may be added.

It is desirable to add an antioxidant to the protective layer (outermost surface layer) 5 for the purpose of preventing the protective layer from being deteriorated by an oxidizing gas such as ozone generated in the charging device. When the mechanical strength of the surface of the photoconductor is increased and the photoconductor has a long life, the photoconductor is in contact with the oxidizing gas for a long time, and therefore, stronger oxidation resistance is required than before.
Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. The addition amount of the antioxidant is preferably 20% by mass or less, and more preferably 10% by mass or less based on the total solid content in the coating liquid (composition) for forming the protective layer.

Examples of the hindered phenol antioxidant include “Irganox 1076”, “Irganox 1010”, “Irganox 1098”, “Irganox 245”, “Irganox 1330”, “Irganox 3114”, “Irganox 1076”. And “3,5-di-tert-butyl-4-hydroxybiphenyl”.
As the hindered amine antioxidants, “Sanol LS2626”, “Sanol LS765”, “Sanol LS770”, “Sanol LS744”, “Tinuvin 144”, “Tinuvin 622LD”, “Mark LA57”, “Mark LA67”, “Mark” LA62 "," Mark LA68 ", and" Mark LA63 "are listed," Sumizer-TPS "and" Smilizer TP-D "are listed as thioethers, and" Mark 2112 "and" Mark PEP-8 "are listed as phosphites. , “Mark PEP-24G”, “Mark PEP-36”, “Mark 329K”, “Mark HP-10”, and the like.

Furthermore, various particles may be added to the protective layer (outermost surface layer) 5 for the purpose of lowering the residual potential of the protective layer or improving the strength.
An example of the particles is silicon-containing particles. The silicon-containing particles are particles containing silicon as a constituent element, and specific examples include colloidal silica and silicone particles. The colloidal silica used as the silicon-containing particles is obtained by dispersing silica having an average particle diameter of 1 nm or more and 100 nm or less, preferably 10 nm or more and 30 nm or less in an organic solvent such as an acidic or alkaline aqueous dispersion, alcohol, ketone, or ester. A commercially available product may be used.
The solid content of colloidal silica in the protective layer 5 is not particularly limited, but 0.1% based on the total solid content of the protective layer 5 in terms of film forming properties, electrical characteristics, and strength. It is used in the range of mass% to 50 mass%, desirably 0.1 mass% to 30 mass%.

The silicone particles used as the silicon-containing particles are selected from silicone resin particles, silicone rubber particles, and silicone surface-treated silica particles, and those commercially available are generally used. These silicone particles are spherical, and the average particle size is desirably 1 nm or more and 500 nm or less, and more desirably 10 nm or more and 100 nm or less. Silicone particles are small particles that are chemically inert and excellent in dispersibility in resin, and since the content required to obtain more sufficient properties is low, the electron does not hinder the crosslinking reaction. The surface properties of the photographic photoreceptor are improved. In other words, it is improved in lubricity and water repellency on the surface of the electrophotographic photosensitive member in a state of being taken in without a variation in a strong cross-linked structure, and has good wear resistance and contamination resistance adhesion over a long period of time. Maintained.
The content of the silicone particles in the protective layer 5 is desirably 0.1% by mass or more and 30% by mass or less, more desirably 0.5% by mass or more and 10% by mass or less, based on the total amount of the total solid content of the protective layer 5. It is.

Other particles include fluorine-based particles such as ethylene tetrafluoride, ethylene trifluoride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, and “8th Polymer Material Forum Lecture Proceedings p89”. As shown, particles made of a resin obtained by copolymerizing a fluororesin and a monomer having a hydroxyl group, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO ₂ —TIO ₂ , ZnO _{-TIO 2, MgO-Al 2 O} 3, FeO-TIO 2, TIO 2, SnO 2, in 2 O 3, ZnO, include semiconductive metal oxides such as MgO.

  For the same purpose, an oil such as silicone oil may be added to the protective layer (outermost surface layer) 5. Silicone oils include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane; amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, methacryl-modified polysiloxane, mercapto-modified poly Reactive silicone oils such as siloxane and phenol-modified polysiloxane; cyclic dimethylcyclosiloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane; 1,3,5- Trimethyl-1.3.5-triphenylcyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclo Cyclic methylphenylcyclosiloxanes such as trasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-pentaphenylcyclopentasiloxane; cyclic phenylcyclosiloxanes such as hexaphenylcyclotrisiloxane Fluorine-containing cyclosiloxanes such as (3,3,3-trifluoropropyl) methylcyclotrisiloxane; hydrosilyl group-containing cyclosiloxanes such as methylhydrosiloxane mixtures, pentamethylcyclopentasiloxane, and phenylhydrocyclosiloxane; penta And vinyl group-containing cyclosiloxanes such as vinylpentamethylcyclopentasiloxane.

  Further, the protective layer (outermost surface layer) 5 may be added with metal, metal oxide, carbon black and the like. Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, or those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony and tantalum-doped tin oxide, and antimony-doped zirconium oxide. . These may be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion. The average particle diameter of the conductive particles is preferably 0.3 μm or less, particularly preferably 0.1 μm or less, from the viewpoint of the transparency of the protective layer.

The composition containing the specific charge transporting material (a) used for forming the protective layer 5 is preferably prepared as a coating liquid for forming the protective layer.
This coating solution for forming the protective layer may be solvent-free, and if necessary, aromatics such as toluene and xylene, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl acetate, butyl acetate and the like. It is prepared using a solvent such as an ester solvent, an ether solvent such as tetrahydrofuran or dioxane, a cellosolv solvent such as ethylene glycol monomethyl ether, or an alcohol solvent such as isopropyl alcohol or butanol.

In addition, when a coating liquid is obtained by reacting the above-mentioned components, each component may be simply mixed and dissolved, but preferably at room temperature to 100 ° C., more preferably at 30 ° C. to 80 ° C., preferably Heating may be performed under conditions of 10 minutes to 100 hours, more preferably 1 hour to 50 hours. It is also desirable to irradiate ultrasonic waves at this time.
As a result, a partial reaction probably proceeds in the coating solution, the uniformity of the coating solution is increased, and a uniform film without coating film defects is easily obtained.

A coating solution for forming a protective layer made of a composition containing a specific charge transport material (a) is formed on the charge transport layer 3 forming the coated surface using a blade coating method, a wire bar coating method, a spray coating method, It is applied by a usual method such as a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method.
Thereafter, a method of applying heat to the obtained coating film to cause radical polymerization is used, whereby the coating film is polymerized and cured.
When the coating film is polymerized and cured by heat, the heating condition is desirably 50 ° C. or higher. Below this temperature, the life of the cured film is short, which is not desirable. In particular, the heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower from the viewpoints of strength, electrical characteristics, and surface uniformity of the photoreceptor.

  In the polymerization and curing reactions as described above, the oxygen concentration is desirably 10% or less, such as in a vacuum or in an inert gas atmosphere, so that the chain reaction can be performed without deactivation of radicals generated by heat. More desirably, it is performed at a low oxygen concentration of 5% or less, more desirably 2% or less, and most desirably 500 ppm or less.

In this embodiment, if the reaction proceeds too quickly, it is difficult to relax the structure of the coating film due to cross-linking, and it is easy to generate unevenness and wrinkles of the film. Is adopted. In particular, when the specific charge transport material (a) has a methacryloyl group having a reactivity lower than that of the acryloyl group, the combination of the methacryloyl group and the curing by heat promotes the structural relaxation of the coating film. The protective layer 5 (outermost surface layer) having excellent properties and high uniformity can be obtained.
On the other hand, when the coating film is cured with light or electron beam, the reaction progresses quickly and tends to be a film with a lot of residual strain, resulting in a film with problems in adhesion to the lower layer and uniformity of the photoreceptor surface. Cheap.

The example of the function-separated type photosensitive layer has been described above with reference to the electrophotographic photoreceptor 7A shown in FIG. 1, but the single-layer type photosensitive layer 6 (charge generation / charge) of the electrophotographic photoreceptor 7C shown in FIG. In the case of a charge transport layer), the following mode is desirable.
That is, the content of the charge generating material in the single-layer type photosensitive layer 6 is about 10% by mass to 85% by mass, desirably 20% by mass to 50% by mass. In addition, the content of the charge transport material is desirably 5% by mass or more and 50% by mass or less. The method for forming the single-layer type photosensitive layer 6 (charge generation / charge transport layer) is the same as the method for forming the charge generation layer 2 and the charge transport layer 3. The film thickness of the single-layer type photosensitive layer (charge generation / charge transport layer) 6 is preferably about 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

Moreover, in the above-mentioned embodiment, although the outermost surface layer which consists of a cured film of the composition containing a specific charge transport material (a) and two kinds of thermal polymerization initiators was described as the protective layer 5, In the case of a layer configuration without the protective layer 5, the charge transport layer located on the outermost surface in the layer configuration is the outermost surface layer.
When the outermost surface layer is a charge transport layer, the thickness of this layer is preferably 7 μm or more and 70 μm or less, and more preferably 10 μm or more and 60 μm or less.

<Conductive substrate>
Examples of the conductive substrate 4 include a metal plate, a metal drum, and a metal belt formed using a metal or an alloy such as aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold, or platinum. Is mentioned. Examples of the conductive substrate 4 include paper, plastic film, belt, etc. coated, vapor-deposited or laminated with a conductive polymer, a conductive compound such as indium oxide, or a metal or alloy such as aluminum, palladium, or gold.
Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member 7A is used in a laser printer, the surface of the conductive substrate 4 has a center line average roughness Ra of 0.04 μm or more to prevent interference fringes generated when laser light is irradiated. It is desirable to roughen the surface to 5 μm or less. If Ra is less than 0.04 μm, it becomes close to a mirror surface, so that the effect of preventing interference tends to be insufficient. If Ra exceeds 0.5 μm, the image quality tends to be rough even if a film is formed. When non-interfering light is used for the light source, it is not particularly necessary to roughen the interference fringes, and it is possible to prevent the occurrence of defects due to the irregularities on the surface of the conductive substrate 4, and thus it is suitable for longer life.

  Surface roughening methods include wet honing by suspending the abrasive in water and spraying it on the support, or centerless grinding and anodic oxidation in which the support is pressed against a rotating grindstone and continuously ground. Processing is desirable.

  As another roughening method, a conductive or semiconductive powder is dispersed in a resin without roughening the surface of the conductive substrate 4 to form a layer on the surface of the support. A method of roughening with particles dispersed in the layer is also desirably used.

  Here, the roughening treatment by anodic oxidation is to form an oxide film on the aluminum surface by anodizing in an electrolyte solution using aluminum as an anode. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, easily contaminated, and has a large resistance fluctuation due to the environment. Therefore, the pores of the anodic oxide film are sealed with pressurized water vapor or boiling water (a metal salt such as nickel may be added) by volume expansion due to a hydration reaction, and a sealing process is performed to change to a more stable hydrated oxide. It is desirable.

  The thickness of the anodic oxide film is desirably 0.3 μm or more and 15 μm or less. When this film thickness is less than 0.3 μm, the barrier property against implantation tends to be poor and the effect tends to be insufficient. On the other hand, if it exceeds 15 μm, the residual potential tends to increase due to repeated use.

  Further, the conductive substrate 4 may be subjected to treatment with an acidic aqueous solution or boehmite treatment. The treatment with an acidic treatment liquid containing phosphoric acid, chromic acid and hydrofluoric acid is carried out as follows. First, an acidic treatment liquid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is such that phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is 0.00%. The concentration of these acids is preferably in the range of 13.5 mass% to 18 mass%. The treatment temperature is preferably 42 ° C. or more and 48 ° C. or less, but by keeping the treatment temperature high, a thicker film can be formed faster than when the treatment temperature is lower than the range. The film thickness is preferably from 0.3 μm to 15 μm. If it is less than 0.3 μm, the barrier property against injection tends to be poor and the effect tends to be insufficient. On the other hand, when it exceeds 15 μm, there is a tendency that the residual potential increases due to repeated use.

  The boehmite treatment is performed by immersing in pure water at 90 ° C. or more and 100 ° C. or less for 5 minutes or more and 60 minutes or less, or by contacting with heated steam at 90 ° C. or more and 120 ° C. or less for 5 minutes or more and 60 minutes or less. The film thickness is preferably 0.1 μm or more and 5 μm or less. This is further anodized using an electrolyte solution having a lower film solubility than other types such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc. It may be processed.

<Underlayer>
The undercoat layer 1 is configured by containing inorganic particles in a binder resin, for example.
As the inorganic particles, those having a powder resistance (volume resistivity) of 10 ² Ω · cm to 10 ¹¹ Ω · cm are desirably used. This is because the undercoat layer 1 is required to obtain appropriate resistance for obtaining leak resistance and carrier blockability. In addition, if the resistance value of the inorganic particles is lower than the lower limit of the above range, sufficient leakage resistance cannot be obtained, and if it is higher than the upper limit of this range, there is a concern that the residual potential is increased.

  Among these, inorganic particles (conductive metal oxide) such as tin oxide, titanium oxide, zinc oxide, and zirconium oxide are preferably used as the inorganic particles having the resistance value, and zinc oxide is particularly preferably used.

Further, the inorganic particles may be subjected to a surface treatment, or may be used by mixing two or more kinds such as those having different surface treatments or particles having different particle diameters.
The volume average particle size of the inorganic particles is desirably in the range of 50 nm to 2000 nm (desirably 60 nm to 1000 nm).

As the inorganic particles, those having a specific surface area of 10 m ² / g or more by the BET method are desirably used. Those having a specific surface area value of less than 10 m ² / g tend to cause a decrease in chargeability and tend to make it difficult to obtain good electrophotographic characteristics.

Furthermore, by containing an acceptor compound together with inorganic particles, an undercoat layer excellent in long-term stability of electric characteristics and carrier blockability can be obtained.
As the acceptor compound, any compound can be used as long as the desired characteristics can be obtained, but quinone compounds such as chloranil and bromoanil, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone. Fluorenone compounds such as 2,4,5,7-tetranitro-9-fluorenone, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, Oxadiazole compounds such as 5-bis (4-naphthyl) -1,3,4-oxadiazole, 2,5-bis (4-diethylaminophenyl) 1,3,4-oxadiazole, xanthone compounds , Thiophene compounds, electron transporting materials such as diphenoquinone compounds such as 3,3 ′, 5,5 ′ tetra-t-butyldiphenoquinone, etc. are desirable In particular compounds having an anthraquinone structure are preferable. Furthermore, acceptor compounds having an anthraquinone structure such as hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, and the like are desirably used, and specific examples include anthraquinone, alizarin, quinizarin, anthralfin, and purpurin.

  The content of these acceptor compounds may be arbitrarily set as long as the desired characteristics are obtained, but desirably it is contained in the range of 0.01% by mass to 20% by mass with respect to the inorganic particles. Is done. Furthermore, from the viewpoint of preventing charge accumulation and preventing inorganic particle aggregation, it is desirable that the inorganic particles be contained in an amount of 0.05% by mass or more and 10% by mass or less. Aggregation of the inorganic particles tends to cause variations in the formation of the conductive path, which not only tends to cause deterioration in sustainability such as an increase in residual potential during repeated use, but also easily causes image quality defects such as black spots.

The acceptor compound may be simply added to the coating solution for forming the undercoat layer, or may be previously attached to the surface of the inorganic particles.
Examples of the method for imparting the acceptor compound to the surface of the inorganic particles include a dry method or a wet method.

  When surface treatment is performed by a dry method, dispersion is achieved by dropping an acceptor compound dissolved in an organic solvent directly or with dry air or nitrogen gas while stirring the inorganic particles with a mixer having a large shearing force. Is processed without any occurrence. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. When spraying at a temperature equal to or higher than the boiling point of the solvent, the solvent evaporates before stirring without causing variation, and the acceptor compound is locally concentrated, which makes it difficult to perform processing without variation. After addition or spraying, baking may be performed at 100 ° C. or higher. Baking is carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained.

  In addition, as a wet method, dispersion occurs when the inorganic particles are dispersed in a solvent using agitation, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., the acceptor compound is added and stirred or dispersed, and then the solvent is removed. Processed without. The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking may be performed at 100 ° C. or higher. Baking is carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the wet method, water containing inorganic particles can also be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in a solvent used for the surface treatment, a method of removing by azeotropic distillation with the solvent May be used.

  The inorganic particles may be subjected to a surface treatment before the acceptor compound is applied. The surface treatment agent is not particularly limited as long as desired characteristics can be obtained, and is selected from known materials. For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, and the like can be given. In particular, silane coupling agents are desirably used because they provide good electrophotographic properties. Further, a silane coupling agent having an amino group is desirably used in order to give a good blocking property to the undercoat layer 1.

  As the silane coupling agent having an amino group, any silane coupling agent may be used as long as it can obtain desired electrophotographic photoreceptor characteristics. Specific examples include γ-aminopropyltriethoxysilane, N- β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxy Although silane etc. are mentioned, it is not limited to these.

  Two or more silane coupling agents may be mixed and used. Examples of silane coupling agents that may be used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyl Trimethoxysilane, etc. The present invention is not limited.

  Further, any surface treatment method using these surface treatment agents can be used as long as it is a known method, but a dry method or a wet method is preferably used. Moreover, you may perform simultaneously provision of an acceptor compound and surface treatment by surface treatment agents, such as a coupling agent.

  The amount of the silane coupling agent with respect to the inorganic particles in the undercoat layer 1 is arbitrarily set as long as the desired electrophotographic characteristics can be obtained. Desirably, the content is from 10% by mass to 10% by mass.

The undercoat layer 1 may contain a binder resin.
As the binder resin contained in the undercoat layer 1, any known resin can be used as long as it can form a good film and can obtain desired characteristics. Acetal resin such as butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride Known polymer resin compounds such as resins, silicone resins, silicone-alkyd resins, phenol resins, phenol-formaldehyde resins, melamine resins and urethane resins, and charge transport resins having a charge transport group and conductive resins such as polyaniline Etc. are used. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferable. When these are used in combination of two or more, the mixing ratio is set as necessary.

  In the coating solution for forming the undercoat layer, the ratio between the inorganic particles (acceptor-provided metal oxide) with the acceptor compound and the binder resin or the inorganic particles and the binder resin is the desired electron. It is arbitrarily set as long as the characteristics of the photographic photoreceptor can be obtained.

In the undercoat layer 1, various additives may be used for improving electrical characteristics, improving environmental stability, and improving image quality.
As additives, known materials such as polycyclic condensation type, azo type electron transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, and the like are used. It is done. The silane coupling agent is used for the surface treatment of the inorganic particles as described above, but may be further added to the coating solution for forming the undercoat layer as an additive.

Specific examples of the silane coupling agent as an additive include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ -Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β Examples include-(aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane.
Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, octanoic acid. Zirconium, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

  These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds.

Solvents for preparing the coating solution for forming the undercoat layer include known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, esters, etc. Optionally selected.
Specific examples of the solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, and acetic acid. Usual organic solvents such as n-butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene are used.

  Moreover, you may use these solvents individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

As a dispersion method of the inorganic particles when preparing the coating liquid for forming the undercoat layer, known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used.
Furthermore, as a coating method used when the undercoat layer 1 is provided, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Is used.

  The undercoat layer 1 is formed on the conductive substrate using the undercoat layer-forming coating solution thus obtained.

The undercoat layer 1 preferably has a Vickers hardness of 35 or more.
Further, the thickness of the undercoat layer 1 is set to any thickness as long as desired characteristics can be obtained. The thickness is preferably 15 μm or more, more preferably 15 μm or more and 50 μm or less.
When the thickness of the undercoat layer 1 is less than 15 μm, sufficient leakage resistance cannot be obtained, and when it is 50 μm or more, residual potential tends to remain when used for a long period of time, so that it tends to cause an abnormal image density. There are drawbacks.

Further, the surface roughness (ten-point average roughness) of the undercoat layer 1 is from 1 / 4n (n is the refractive index of the upper layer) to 1 / 2λ of the exposure laser wavelength λ used to prevent moire images. Adjusted to
In order to adjust the surface roughness, particles such as a resin may be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked polymethyl methacrylate resin particles, and the like are used.
Further, the surface of the undercoat layer may be polished for adjusting the surface roughness.
As a polishing method, buffing, sandblasting, wet honing, grinding, or the like can be used.

  The undercoat layer 1 can be obtained by drying the above-described undercoat layer forming coating solution applied on the conductive substrate 4, and the drying is usually performed at a temperature at which the solvent can be evaporated and the film can be formed. Is called.

<Charge generation layer>
The charge generation layer 2 is a layer containing a charge generation material and a binder resin.
Examples of the charge generation material include azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, perylene pigments, pyrrolopyrrole pigments, phthalocyanine pigments, zinc oxide, and trigonal selenium. Among these, it is desirable to use a metal phthalocyanine pigment and a metal-free phthalocyanine pigment as the charge generation material in order to cope with near-infrared laser exposure, and in particular, JP-A-5-263007 and JP-A-5 -279591, etc., hydroxygallium phthalocyanine, chlorogallium phthalocyanine disclosed in JP-A-5-98181, etc., dichlorogallium phthalocyanine disclosed in JP-A-5-140472, JP-A-5-140473, etc. Tin phthalocyanine, titanyl phthalocyanine disclosed in JP-A-4-189873, JP-A-5-43823 and the like are more preferable. Further, in order to cope with near-ultraviolet laser exposure, as a charge generation material, a condensed aromatic pigment such as dibromoanthanthrone, a thioindigo pigment, a porphyrazine compound, zinc oxide, trigonal selenium, It is more desirable to use bisazo pigments and the like disclosed in JP-A-78147 and JP-A-2005-181992.

The binder resin used for the charge generation layer 2 is selected from a wide range of insulating resins, and selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Also good. Desirable binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic divalent carboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamides. Resins, acrylic resins, polyacrylamide resins, polyvinyl pyridine resins, cellulose resins, urethane resins, epoxy resins, caseins, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, and the like. These binder resins are used singly or in combination of two or more. The blending ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio. Here, “insulating” means here that “insulating” means that the volume resistivity is 10 ¹³ Ωcm or more.
The blending ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio.

  The charge generation layer 2 is formed using a charge generation layer forming coating solution in which the above-described charge generation material and binder resin are dispersed in a predetermined solvent.

  Solvents used for dispersion include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, and methylene chloride. , Chloroform, chlorobenzene, toluene and the like. These may be used alone or in admixture of two or more.

In addition, as a method for dispersing the charge generating material and the binder resin in the solvent, usual methods such as a ball mill dispersion method, an attritor dispersion method, and a sand mill dispersion method can be used. By these dispersion methods, changes in the crystal form of the charge generation material due to dispersion are prevented.
Further, at the time of dispersion, it is effective that the average particle size of the charge generation material is 0.5 μm or less, desirably 0.3 μm or less, and more desirably 0.15 μm or less.

  Further, when forming the charge generation layer 2, a usual method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. .

  The film thickness of the charge generation layer 2 obtained in this manner is desirably 0.1 μm or more and 5.0 μm or less, and more desirably 0.2 μm or more and 2.0 μm or less.

<Charge transport layer>
The charge transport layer 3 is formed containing a charge transport material and a binder resin, or containing a polymer charge transport material.
Charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds Electron transporting compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. A hole transporting compound may be mentioned. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

  As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are desirable.

In the structural formula (a-1), R ⁹ represents a hydrogen atom or a methyl group. l represents 1 or 2; Ar ⁶ and Ar ⁷ are each independently a substituted or unsubstituted aryl group, —C ₆ H ₄ —C (R ¹⁰ ) ═C (R ¹¹ ) (R ¹² ), or —C ₆ H ₄ —CH═CH— CH = C (R ¹³ ) (R ¹⁴ ), wherein R ^{10 to} R ¹⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Here, the substituent of each of the above groups is a substituent substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 3 carbon atoms. An amino group is mentioned.

In the structural formula (a-2), R ¹⁵ and R ^{15 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ¹⁶ , R ^{16 ′} , R ¹⁷ and R ^{17 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 2 carbon atoms. An amino group substituted with the following alkyl group, a substituted or unsubstituted aryl group, —C (R ¹⁸ ) ═C (R ¹⁹ ) (R ²⁰ ), or —CH═CH—CH═C (R ²¹ ) ( R ²² ), and each of R ^{18 to} R ²² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. m and n each independently represent an integer of 0 or more and 2 or less.

Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, “—C ₆ H ₄ —CH═CH—CH ═C (R ¹³ ) (R ¹⁴ ) ”and a benzidine derivative having“ —CH═CH—CH═C (R ²¹ ) (R ²² ) ”have charge mobility, protective layer and It is excellent and desirable from the standpoints of adhesiveness and afterimage (hereinafter sometimes referred to as “ghost”) caused by the history of the previous image remaining.

The binder resin used for the charge transport layer 3 is polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer. , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly- N-vinyl carbazole, polysilane, etc. are mentioned. Of these, polycarbonate resins and polyarylate resins are preferable because of their excellent charge transportability and compatibility with charge transport materials.
These binder resins are used singly or in combination of two or more. The blending ratio of the charge transport material and the binder resin is desirably 10: 1 to 1: 5 by mass ratio.

In particular, the charge transport layer 3 includes a protective layer (outermost surface layer) made of a cured film of a composition containing a specific charge transport material (a) and two or more thermal polymerization initiators (b). Therefore, the binder resin used for the charge transport layer 3 is preferably one having a viscosity average molecular weight of 50000 or more, and more preferably 55000 or more. Use of a binder resin having such a molecular weight is desirable because it is excellent in adhesiveness and crack resistance when forming a protective layer (outermost surface layer).
The upper limit of the viscosity average molecular weight of the binder resin used for the charge transport layer 3 is preferably 100000 from the viewpoint of the uniformity (liquid dripping) of the coating film.
Here, the viscosity average molecular weight of the binder resin in the present embodiment is a value measured by a capillary viscometer.
For the same reason, when the outermost layer is a charge transport layer, the viscosity average molecular weight of the binder resin contained in the lower layer is preferably within the above range.

  In addition, a polymer charge transport material may be used as the charge transport material. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293, JP-A-8-208820 and the like have a higher charge transportability than other types, and are particularly desirable. is there. The polymer charge transport material can be formed by itself, but may be formed by mixing with the above-described binder resin.

The charge transport layer 3 is formed using a charge transport layer forming coating solution containing the above-described constituent materials.
Solvents used in the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenation such as methylene chloride, chloroform and ethylene chloride. Ordinary organic solvents such as aliphatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, or straight chain ethers may be used alone or in admixture of two or more. Moreover, a well-known method is used as a dispersion method of each said constituent material.

  The coating method for applying the charge transport layer forming coating solution onto the charge generation layer 2 includes blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, A usual method such as a curtain coating method is used.

  The film thickness of the charge transport layer 3 is desirably 5 μm or more and 50 μm or less, and more desirably 10 μm or more and 30 μm or less.

[Image forming apparatus / process cartridge]
FIG. 4 is a schematic configuration diagram illustrating the image forming apparatus 100 according to the embodiment.
An image forming apparatus 100 shown in FIG. 4 includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device (electrostatic latent image forming unit) 9, a transfer device (transfer unit) 40, and an intermediate transfer member 50. . In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed from the opening of the process cartridge 300, and the transfer device 40 is interposed between the electrophotographic photosensitive member via the intermediate transfer member 50. 7, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photosensitive member 7.

  A process cartridge 300 in FIG. 4 integrally supports an electrophotographic photosensitive member 7, a charging device (charging means) 8, a developing device (developing means) 11, and a cleaning device 13 in a housing. The cleaning device 13 has a cleaning blade (cleaning member), and the cleaning blade 131 is disposed so as to contact the surface of the electrophotographic photosensitive member 7. The cleaning member is not an aspect of the cleaning blade 131 but may be a conductive or insulating fibrous member, which may be used alone or in combination with a blade.

  Further, in FIG. 4, as the cleaning device 13, a fibrous member 132 (roll shape) that supplies the lubricant 14 to the surface of the photoreceptor 7 and a fibrous member 133 (flat brush shape) that assists cleaning is used. Examples are shown, but these are used as needed.

  As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like is used. Further, a non-contact type roller charger, a known charger such as a scorotron charger using a corona discharge or a corotron charger may be used.

  Although not shown, a photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member 7 and reducing the relative temperature is provided around the electrophotographic photosensitive member 7 for the purpose of improving the stability of the image. Also good.

  Examples of the exposure apparatus 9 include optical system devices that expose the surface of the photoconductor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a desired image-like manner. The wavelength of the light source is in the spectral sensitivity region of the photoreceptor. As the wavelength of the semiconductor laser, near infrared having an oscillation wavelength near 780 nm is the mainstream. However, the present invention is not limited to this wavelength, and an oscillation wavelength laser in the 600 nm range or a laser having an oscillation wavelength in the vicinity of 400 nm to 450 nm as a blue laser may be used. For color image formation, a surface-emitting laser light source capable of multi-beam output is also effective.

  As the developing device 11, for example, a general developing device that performs development by bringing a magnetic or non-magnetic one-component developer or a two-component developer into contact or non-contact may be used. The developing device is not particularly limited as long as it has the functions described above, and is selected according to the purpose. For example, a known developing device having a function of attaching the one-component developer or the two-component developer to the photoreceptor 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding the developer on the surface are desirable.

Hereinafter, the toner used in the developing device 11 will be described.
Such toner has an average shape factor (ML ² / A × π / 4 × 100, where ML represents the maximum length of toner particles and A represents the projected area of toner particles) of 100 to 150. Is desirable, and it is more desirable that it is 100 or more and 140 or less. Further, the toner preferably has a volume average particle size of 2 μm or more and 12 μm or less, more preferably 3 μm or more and 12 μm or less, and further preferably 3 μm or more and 9 μm or less. By using the toner satisfying the average shape factor and the volume average particle diameter in this way, an image with higher development, transferability, and high image quality can be obtained compared to other toners.

  The toner is not particularly limited by the production method as long as it satisfies the above average shape factor and volume average particle diameter. For example, the toner may include a binder resin, a colorant, a release agent, and the like. A kneading and pulverizing method in which a charge control agent is added, kneading, pulverizing, and classifying; a method in which the shape of particles obtained by the kneading and pulverizing method is changed by mechanical impact force or thermal energy; Emulsion polymerization of the body, and the resulting dispersion is mixed with a dispersion of a colorant, a release agent and, if necessary, a charge control agent, and then agglomerated and heat-fused to obtain toner particles. Suspension polymerization method in which a polymerizable monomer for obtaining a binder resin, a colorant, a release agent, and a charge control agent, if necessary, are suspended in an aqueous solvent and polymerized; A water-based solution of a resin, a colorant, a release agent, and a solution such as a charge control agent as necessary. Toner is used which is suspended in and produced by a dissolution suspension method in which granulated.

  In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure may be used. The toner production method is preferably a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method in which an aqueous solvent is used from the viewpoint of shape control and particle size distribution control, and an emulsion polymerization aggregation method is particularly desirable.

  The toner base particles are composed of a binder resin, a colorant, and a release agent, and include silica and a charge control agent as necessary.

  Binder resins used for toner base particles include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Α-methylene aliphatics such as vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers of monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone Polyester resins by copolymerization of dicarboxylic acids and diols.

  Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. A polymer, polyethylene, a polypropylene, a polyester resin etc. are mentioned. Further, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

  Further, as colorants, magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, Lamp Black, Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is exemplified as a representative example.

  Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropical wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  As the charge control agent, known ones are used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When toner is produced by a wet process, it is desirable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The toner used in the developing device 11 is manufactured by mixing the toner base particles and the external additive with a Henschel mixer or a V blender. In addition, when the toner base particles are produced by a wet method, external addition can also be performed by a wet method.

  Lubricating particles may be added to the toner used in the developing device 11. Lubricating particles include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids and fatty acid metal salts, low molecular weight polyolefins such as polypropylene, polyethylene and polybutene, silicones having a softening point upon heating, oleic amides , Aliphatic amides such as erucic acid amide, ricinoleic acid amide, stearic acid amide, etc., plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, animal waxes such as beeswax, Minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax, and petroleum-based waxes, and modified products thereof are used. These are used individually by 1 type or in combination of 2 or more types. However, the volume average particle diameter is preferably in the range of 0.1 μm or more and 10 μm or less, and those having the above chemical structure may be pulverized to make the particle diameters uniform. The amount added to the toner is desirably in the range of 0.05% by mass to 2.0% by mass, and more desirably in the range of 0.1% by mass to 1.5% by mass.

  To the toner used in the developing device 11, inorganic particles, organic particles, composite particles obtained by attaching inorganic particles to the organic particles, and the like may be added for the purpose of removing deposits and deteriorated materials on the surface of the electrophotographic photosensitive member. .

  Inorganic particles include silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, Various inorganic oxides such as manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride, nitrides, borides, and the like are preferably used.

  In addition, the inorganic particles may be mixed with titanium coupling agents such as tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, γ- (2- Aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxy Silane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane The treatment may be performed with a silane coupling agent such as run, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane. In addition, those hydrophobized with higher fatty acid metal salts such as silicone oil, aluminum stearate, zinc stearate, calcium stearate and the like are also desirably used.

  Organic particles include graphite, fluorocarbon with fluorine bonded to graphite, polytetrafluoroethylene resin (PTFE), perfluoroalkoxy / fluorine resin (PFA), ethylene tetrafluoride / hexafluoropropylene copolymer ( Particles such as FEP), ethylene / tetrafluoroethylene copolymer (ETFE), polychloroethylene trifluoride (PCTFE), vinylidene fluoride (PVDF), and vinyl fluoride (PVF) can be used.

  The particle diameter is preferably 5 nm to 1000 nm, more preferably 5 nm to 800 nm, and even more preferably 5 nm to 700 nm in terms of volume average average particle diameter. If the volume average particle diameter is less than the lower limit, the polishing ability tends to be lacking. On the other hand, if the volume average particle diameter exceeds the upper limit, the surface of the electrophotographic photosensitive member tends to be damaged. Moreover, it is desirable that the sum of the addition amounts of the above-described particles and the lubricating particles is 0.6% by mass or more.

  As other inorganic oxides added to the toner, a small-diameter inorganic oxide having a primary particle size of 40 nm or less is used for powder fluidity, charge control, etc. It is desirable to add a larger diameter inorganic oxide. These inorganic oxide particles may be known ones, but it is desirable to use silica and titanium oxide in combination for precise charge control. Further, the surface treatment of the small-diameter inorganic particles increases the dispersibility and increases the effect of increasing the powder fluidity. Furthermore, it is desirable to add carbonates such as calcium carbonate and magnesium carbonate and inorganic minerals such as hydrotalcite in order to remove the discharge purified product.

  The color toner for electrophotography is used by mixing with a carrier. As the carrier, iron powder, glass beads, ferrite powder, nickel powder, or those having a resin coating on the surface thereof are used. The mixing ratio with the carrier is arbitrarily set.

  As the transfer device 40, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade, etc., or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

  As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber or the like having semiconductivity is used. Further, as the form of the intermediate transfer member 50, a drum-like one is used in addition to the belt shape.

  In addition to the above-described devices, the image forming apparatus 100 may include, for example, a light neutralizing device that performs light neutralization on the photoconductor 7.

FIG. 5 is a schematic cross-sectional view showing an image forming apparatus 120 according to another embodiment.
An image forming apparatus 120 shown in FIG. 5 is a tandem type full-color image forming apparatus equipped with four process cartridges 300.
In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used for one color. The image forming apparatus 120 has the same configuration as that of the image forming apparatus 100 except that it is a tandem system.

  When the electrophotographic photosensitive member of the present invention is used in a tandem type image forming apparatus, the electric characteristics of the four photosensitive members are stabilized, so that an image quality with excellent color balance can be obtained over a longer period.

  Further, in the image forming apparatus (process cartridge) according to the present embodiment, the developing device (developing means) is a developer holder that moves (rotates) in the opposite direction to the moving direction (rotating direction) of the electrophotographic photosensitive member. It is desirable to have a developing roller that is Here, the developing roller has a cylindrical developing sleeve that holds developer on the surface, and the developing device has a configuration that includes a regulating member that regulates the amount of developer supplied to the developing sleeve. Can be mentioned. By moving (rotating) the developing roller of the developing device in a direction opposite to the rotation direction of the electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is rubbed with toner remaining between the developing roller and the electrophotographic photosensitive member. The Further, when cleaning the toner remaining on the electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is increased by, for example, increasing the pressing pressure of a blade or the like in order to improve the cleaning property of the toner having a shape close to a spherical shape. Strong rubbing.

Due to these rubbing, conventionally known electrophotographic photoreceptors are strongly damaged, and wear, scratches, toner filming, etc. are likely to occur and image degradation has occurred. A thick film because of its excellent electrical characteristics, which is enhanced by a cross-linked product of a charge transporting material (especially, a material capable of obtaining a cured film having a high cross-linking density and having a high concentration of reactive functional groups and contained in a high concentration). By forming the surface of the electrophotographic photosensitive member, it has become possible to maintain high image quality over a long period of time. It is considered that deposition of such discharge products is suppressed for an extremely long time.
In the image forming apparatus of the present embodiment, the distance between the developing sleeve and the photosensitive member is preferably 200 μm or more and 600 μm or less, and more preferably 300 μm or more and 500 μm, from the viewpoint of suppressing the accumulation of discharge products over a longer period. The following is more desirable. From the same point of view, the distance between the developing sleeve and the regulating blade, which is a regulating member that regulates the developer amount, is desirably 300 μm or more and 1000 μm or less, and more desirably 400 μm or more and 750 μm or less.
Further, from the viewpoint of suppressing the accumulation of discharge products for a longer period, the absolute value of the moving speed of the developing roll surface is 1.5 times or more the absolute value (process speed) of the moving speed of the photoreceptor surface. Desirably, it is 5 times or less, and more desirably 1.7 times or more and 2.0 times or less.

  Further, in the image forming apparatus (process cartridge) according to the present embodiment, the developing device (developing unit) includes a developer holding body having a magnetic material, and is a two-component developer containing a magnetic carrier and toner. It is desirable to develop an image. In this configuration, a clearer image quality can be obtained with a color image, and higher image quality and longer life can be achieved compared to the case of a one-component developer, particularly a non-magnetic one-component developer.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(Synthesis Example 1: Synthesis of Compound A-4)

  10 g of the above compound (1), 50 g of hydroxyethyl methacrylate, 20 ml of tetrahydrofuran and 0.5 g of Amberlyst 15E (manufactured by Organo) were added to a 200 ml flask and stirred at room temperature for 24 hours. After completion of the reaction, 100 ml of methanol was added, and the precipitated oil was taken out by decantation. This oily substance was purified by silica gel column chromatography to obtain 12 g of oily (A-4). FIG. 7 shows the IR spectrum of the obtained (A-4).

(Synthesis Example 2: Synthesis of Compound A-17)

  To a 500 ml flask, 36 g of the above compound (2), 75 g of methacrylic acid, 300 ml of toluene and 2 g of p-toluenesulfonic acid were added and heated to reflux for 10 hours. After the reaction, it was cooled, poured into 2000 ml of water, washed, and further washed with water. The toluene layer was dried over anhydrous sodium sulfate and then purified by silica gel column chromatography to obtain 30 g of (A-17). FIG. 8 shows the IR spectrum of the obtained (A-17).

(Synthesis Example 3: Synthesis of Compound A-18)

  50 g of the above compound (3), 107 g of methacrylic acid, 300 ml of toluene, and 2 g of p-toluenesulfonic acid were added to a 500 ml flask and heated to reflux for 10 hours. After the reaction, it was cooled, poured into 2000 ml of water, washed, and further washed with water. The toluene layer was dried over anhydrous sodium sulfate and then purified by silica gel column chromatography to obtain 38 g of (A-18). FIG. 9 shows the IR spectrum of the obtained (A-18).

(Comparative Synthesis Example-1)
To a 500 ml flask, 36 g of the compound (2), 70 g of acrylic acid, 300 ml of toluene and 2 g of p-toluenesulfonic acid were added and heated to reflux for 10 hours. After the reaction, it was cooled, poured into 2000 ml of water, washed, and further washed with water. The toluene layer was dried over anhydrous sodium sulfate and purified by silica gel column chromatography. However, the solvent was gelated during distillation under reduced pressure, and the target product could not be isolated.

(Comparative Synthesis Example-2)
After performing the reaction by adding 0.5 g of hydroquinone to Comparative Synthesis Example-1, the same treatment as in Comparative Synthesis Example-1 was performed, but the solvent was gelated during distillation under reduced pressure to isolate the target product. I couldn't.

Hereinafter, materials used in Examples and Comparative Examples are shown.
<Particle>
・ Colloidal silica (trade name: PL-1, manufactured by Fuso Chemical Industries)
・ Titanium oxide (tItone R-1T, manufactured by Sakai Chemical Co., Ltd.)
・ PTFE (trade name: Lubron L-2, manufactured by Daikin Chemical Industries)

<Polymers ( d ) and ( e )>
Bisphenol (Z) polycarbonate ((PC (Z), molecular weight 40,000, manufactured by Mitsubishi Gas Chemical Industries, Ltd.): a polymer that does not react with a specific charge transport material (a) ( d )
Polymethyl methacrylate (PMMA, molecular weight 20,000): a polymer that does not react with a specific charge transport material (a) ( d )
Polycarbonate having a carbon-carbon double bond described in JP-A-5-323630 (R-resin, molecular weight 20,000): a polymer ( e ) that reacts with a specific charge transporting material (a)

<Monomer (c) which does not have charge transport property which reacts with specific charge transport material (a ) : Curing agent>
・ Isobutyl acrylate (IBA, Wako Pure Chemical Industries)
・ Ethoxylated bisphenol diacrylate (ABE-300, manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ Trimethylolpropane triacrylate (THE330, manufactured by Nippon Kayaku Co., Ltd.)

<Thermal polymerization initiator (b)>
AIBM: Azoisobutyl nitrile (10 hour half-life temperature: 65 ° C., manufactured by Otsuka Chemical)
V-30 (10 hour half-life temperature: 104 ° C., manufactured by Wako Pure Chemical Industries, Ltd.)
V-601 (10 hour half-life temperature: 66 ° C., manufactured by Wako Pure Chemical Industries)
・ OT _AZO- 15 (10 hour half-life temperature: 61 ° C., manufactured by Otsuka Chemical)
V-40 (10 hour half-life temperature: 88 ° C., manufactured by Wako Pure Chemical Industries)
・ Lupelox TAP (10 hours half-life temperature: 100 ° C, manufactured by Arkema Yoshitomi)
・ Lupelox 26 (10-hour half-life temperature: 77 ° C, manufactured by Arkema Yoshitomi)

[Example 1]
(Formation of undercoat layer)
Zinc oxide: (average particle diameter 70 nm: manufactured by Teica Co., Ltd .: specific surface area value 15 m ² / g) 100 parts by mass was stirred and mixed with 500 parts by mass of tetrahydrofuran, and silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.3 parts by mass Part was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.
110 parts by mass of the surface-treated zinc oxide was stirred and mixed with 500 parts by mass of tetrahydrofuran, a solution prepared by dissolving 0.6 parts by mass of alizarin in 50 parts by mass of tetrahydrofuran was added, and the mixture was stirred at 50 ° C. for 5 hours. did. Then, the zinc oxide to which alizarin was imparted by filtration under reduced pressure was filtered off, and further dried at 60 ° C. under reduced pressure to obtain zinc oxide to which alizarin was imparted.

  Zinc oxide provided with this alizarin: 60 parts by mass, curing agent (blocked isocyanate Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.): 13.5 parts by mass, butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.) ): 15 parts by mass of 38 parts by mass of methyl ethyl ketone mixed with 85 parts by mass of methyl ethyl ketone: 25 parts by mass of methyl ethyl ketone were mixed, and dispersion was performed for 2 hours with a sand mill using glass beads having a diameter of 1 mmφ. Got.

  Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone): 40 parts by mass were added as catalysts to the obtained dispersion to obtain a coating liquid for forming an undercoat layer. . This coating solution was applied on an aluminum substrate having a diameter of 30 mm, a length of 340 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 18 μm.

(Formation of charge generation layer)
Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα characteristic X-ray as a charge generating material are at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° A mixture consisting of 15 parts by mass of hydroxygallium phthalocyanine having a diffraction peak, 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar) as a binder resin, and 200 parts by mass of n-butyl acetate. The mixture was dispersed for 4 hours in a sand mill using glass beads having a diameter of 1 mmφ. To the obtained dispersion, 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added and stirred to obtain a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was dip coated on the undercoat layer and dried at room temperature (25 ° C.) to form a charge generation layer having a thickness of 0.2 μm.

(Formation of charge transport layer)
45 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and bisphenol Z polycarbonate resin (viscosity average molecular weight: 80,000) ) 55 parts by mass was added to 800 parts by mass of chlorobenzene and dissolved to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 130 ° C. for 45 minutes to form a charge transport layer having a thickness of 15 μm.

(Formation of protective layer)
30 parts by mass of a specific charge transport material (Compound A-4), 0.2 parts by mass of colloidal silica (trade name: PL-1, manufactured by Fuso Chemical Industries), 30 parts by mass of toluene, 3,5-di-t- 0.1 part by mass of butyl-4-hydroxytoluene (BHT), 0.1 part by mass of azoisobutyronitrile (10 hour half-life temperature: 65 ° C.), and V-30 (10 hour half-life temperature: 104 ° C.) Was added to prepare a coating solution for forming a protective layer. This coating solution is applied onto the charge transport layer by a spray coating method and air-dried at room temperature for 30 minutes, and then heated from room temperature to 150 ° C. at an oxygen concentration of 110 ppm for 30 minutes in a nitrogen stream, and further at 30 ° C. for 30 minutes. A protective layer having a thickness of 10 μm was formed by curing by heat treatment for a few minutes.
An electrophotographic photoreceptor was obtained by the method as described above. This photoreceptor is referred to as a photoreceptor 1.

[Evaluation]
-Image quality evaluation-
The electrophotographic photosensitive member produced as described above is mounted on Fuji Xerox Co., Ltd., DocuCentre Color 400CP, and at low temperature and low humidity (8 ° C., 20% RH) and high temperature and high humidity (28 ° C., 85% RH), the following Evaluation was performed continuously.
That is, first, an image formation test of 5000 sheets is performed in an environment of low temperature and low humidity (8 ° C., 20% RH), and the image quality of the 5000th image and the 5000 sheet image formation test are performed. The following image quality uniformity, fog, streak, and image flow were evaluated for the image quality of the first image after the image forming apparatus was left for 24 hours in a low humidity (8 ° C., 20% RH) environment.
The evaluation results are shown in Table 4.

Then, following the image formation test and image quality evaluation under the low temperature and low humidity environment, the 5000th image formation test is performed under the environment of high temperature and high humidity (28 ° C., 85% RH). After the image formation test of 5000 sheets and the image formation test of 5000 sheets, the image quality of the first image after leaving the image forming apparatus in a high temperature and high humidity (28 ° C., 85% RH) environment for 24 hours is as follows: Sex, fog, streaks, and image flow were evaluated.
The evaluation results are shown in Table 5.
For the image forming test, Fuji Xerox P paper (A4 size, lateral feed) was used.

<Evaluation of image quality uniformity>
For the image quality uniformity, the chart shown in FIG. 6 and a pattern having a black area with a density of 30% was printed, and the density unevenness of the black area with a density of 30% was visually evaluated.
A: Density unevenness is good to slight.
B: Density unevenness is slightly noticeable.
C: It shows that density unevenness can be confirmed clearly.

<Evaluation of fog>
The fog was determined by visually observing the degree of toner adhesion on the white background using the same sample as the above-described evaluation of image quality uniformity.
A: Good.
B: There is a slight fog.
C: There is fogging that causes a problem in image quality.

<Evaluation of streaks>
The streak was visually determined using the same sample as in the above evaluation of image quality uniformity.
A: Good.
B: Streaks are partially generated.
C: Streaks that cause image quality problems.

<Evaluation of image flow>
The image flow was judged visually by using the same sample as the image quality uniformity evaluation described above, and the blurring of the black line in the 30% density was visually observed.
A: Good.
B: There is no problem when continuously performing a print test, but blurring occurs after leaving for 1 day (24 hours).
C: Blurred even during continuous print test.

-Evaluation of protective layer (outermost surface layer)-
The adhesiveness, surface roughness, and wear amount of the protective layer (outermost surface layer) were evaluated as follows.

<Evaluation of adhesiveness of protective layer>
The adhesiveness of the protective layer is as follows: 5 × 5 cuts at 2 mm square are cut with a cutter knife on the photoconductor after a total of about 10,000 image forming tests at low temperature and low humidity and high temperature and high humidity as described above. A 3M mending tape was applied and evaluated by the remaining number when peeled.
It can be seen that the greater the remaining number, the better the adhesion with the lower charge transport layer.
A: 21 or more remained.
B: 11 to 20 remaining.
C: 10 or less remained.
The evaluation results are shown in Table 4.

<Evaluation of surface roughness of outermost surface layer>
The ten-point average roughness Rz (μm) of the photoreceptor surface before the image formation test was measured with a surface roughness shape measuring device SURFCOM 1400D (manufactured by Tokyo Seimitsu Co., Ltd.).
The evaluation results are shown in Table 4.

<Measurement of wear amount of outermost layer>
The amount of wear on the outermost surface layer was measured by measuring the film thickness of the photoconductor after a total of about 10,000 image forming tests at low temperature and low humidity and high temperature and high humidity, and comparing it with the film thickness of the photoconductor before the image forming test. Thus, the wear amount of the outermost surface layer was calculated. For the measurement, an eddy current film thickness meter (Surfix N: manufactured by PHYNIX) was used.
It can be seen that the smaller the amount of wear, the higher the mechanical strength of the outermost layer.
The evaluation results are shown in Table 5.

[Examples 2 to 13]
In accordance with the following Table 1, the specific charge transport material (a) and the types of various additives (particles, polymers, curing agents, antioxidants, and thermal polymerization initiators), and the blending amounts thereof were changed. Except for the above, photoconductors 2 to 13 were produced in the same manner as in [Example 1] and evaluated. Note that the thickness of the protective layer was adjusted to a thickness at which an appropriate potential can be obtained with DocuCenter Color 400CP.
The evaluation results are shown in Tables 4 and 5.

[Example 14]
Except for changing the formation of the charge transport layer as follows, a photoconductor 14 was prepared and evaluated in the same manner as in [Example 1]. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
45 parts by mass of the compound (a) having the following structure and 55 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 40,000) were added to 800 parts by mass of chlorobenzene and dissolved to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 130 ° C. for 45 minutes to form a charge transport layer having a thickness of 17 μm.

[Example 15]
Except for changing the formation of the charge transport layer as follows, a photoconductor 15 was prepared and evaluated in the same manner as in [Example 1]. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
50 parts by mass of the compound (b) having the following structure and 50 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 50,000) were added to 800 parts by mass of chlorobenzene and dissolved to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 130 ° C. for 45 minutes to form a charge transport layer having a thickness of 15 μm.

<Example 16>
Except that the formation of the charge transport layer was changed as follows, a photoconductor 16 was prepared and evaluated in the same manner as in [Example 1]. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
50 parts by mass of the compound (c) having the following structure and 50 parts by mass of a bisphenol Z polycarbonate resin (viscosity average molecular weight: 80,000) were added to 800 parts by mass of chlorobenzene and dissolved to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 130 ° C. for 45 minutes to form a charge transport layer having a thickness of 15 μm.

[Example 17]
A photoconductor 17 was prepared in the same manner as in [Example 1] except that the binder resin used for forming the charge transport layer was replaced with a bisphenol Z polycarbonate resin (viscosity average molecular weight: 40,000). went.
The evaluation results are shown in Tables 4 and 5.

[Example 18]
The formation up to the charge generation layer was performed in the same manner as in [Example 1]. Thereafter, a charge transport layer was formed as follows to produce a photoreceptor 18, and the same evaluation as in [Example 1] was performed. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
60 parts by mass of a specific charge transport material (Compound A-4), 0.2 parts by mass of colloidal silica (trade name: PL-1, manufactured by Fuso Chemical Industries), 30 parts by mass of toluene, 3,5-di-t- 0.1 part by mass of butyl-4-hydroxytoluene (BHT), 0.1 part by mass of azoisobutyronitrile (10 hour half-life temperature: 65 ° C.), and V-30 (10 hour half-life temperature: 104 ° C.) A coating solution for charge transport layer was prepared by mixing 0.15 parts by mass. This coating solution is applied onto the charge generation layer by a dip coating method and air-dried at room temperature for 30 minutes, and then heated from room temperature to 150 ° C. over 30 minutes at an oxygen concentration of 110 ppm under a nitrogen stream. A photoconductor of Example 18 was produced by curing by heating for 30 minutes to form a charge transport layer having a thickness of 30 μm.

[Example 19]
The formation up to the charge generation layer was performed in the same manner as in [Example 1]. Thereafter, a charge transport layer was formed as follows to produce a photoconductor 19, and the same evaluation as in [Example 1] was performed. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
30 parts by mass of a specific charge transport material (Compound A-4), 10 parts by mass of the compound (b), 10 parts by mass of PC (Z), 30 parts by mass of toluene, 3,5-di-t-butyl-4-hydroxy Toluene (BHT) 0.1 parts by mass, azoisobutyronitrile (10 hours half-life temperature: 65 ° C.) 0.1 parts by mass, and V-30 (10 hours half-life temperature: 104 ° C.) 0.15 parts by mass Were mixed to prepare a coating solution for charge transport layer. This coating solution is applied onto the charge generation layer by a dip coating method and air-dried at room temperature for 30 minutes, and then heated from room temperature to 150 ° C. over 30 minutes at an oxygen concentration of 110 ppm under a nitrogen stream. A photoconductor of Example 19 was prepared by curing by heating for 30 minutes to form a charge transport layer having a thickness of 30 μm.

[Example 20]
The formation up to the charge generation layer was performed in the same manner as in [Example 1]. Thereafter, a charge transport layer was formed as follows to produce a photoconductor 20, and evaluation similar to [Example 1] was performed. The evaluation results are shown in Tables 4 and 5.

(Formation of charge transport layer)
30 parts by mass of a specific charge transport material (Compound A-4), 10 parts by mass of the compound (c), 10 parts by mass of PC (Z), 30 parts by mass of toluene, 3,5-di-t-butyl-4-hydroxy Toluene (BHT) 0.1 part by mass, azoisobutyronitrile (10 hour half-life temperature: 65 ° C.) 0.2 part by mass, and V-30 (10 hour half-life temperature: 104 ° C.) 0.1 part by mass Were mixed to prepare a coating solution for charge transport layer. This coating solution is applied onto the charge generation layer by a dip coating method and air-dried at room temperature for 30 minutes, and then heated from room temperature to 150 ° C. over 30 minutes at an oxygen concentration of 110 ppm under a nitrogen stream. A photoconductor of Example 20 was produced by curing by heating for 30 minutes to form a charge transport layer having a thickness of 30 μm.

[Comparative Examples 1 to 4]
Comparative photoreceptors 1 to 4 were prepared in the same manner as in [Example 1] except that the thickness of the charge transport layer was 30 μm and no protective layer was provided, and evaluation was performed in the same manner as in [Example 1].
The evaluation results are shown in Tables 4 and 5.

[Comparative Examples 5 to 10]
In accordance with Table 3 below, specific charge transport materials (a), other charge transport materials, and various additives (particles, polymers, curing agents, antioxidants, thermal polymerization initiators) types, and these Comparative photoreceptors 5 to 10 were prepared and evaluated in the same manner as in [Example 1] except that the blending amount of was changed. Note that the thickness of the protective layer was adjusted to a thickness at which an appropriate potential can be obtained with DocuCenter Color 400CP.
The evaluation results are shown in Tables 4 and 5.

As shown in Tables 4 and 5, in this example, it can be seen that all of image uniformity, fogging, streaks, and image flow are good and the evaluation of adhesiveness is excellent as compared with the comparative example. .
Further, the surface roughness of Comparative Examples 5 to 10 is much larger than that of Examples, and it is considered that residual distortion occurs in the outermost surface layer.
When the electrophotographic photosensitive member of the comparative example is used, the evaluation in the image formation test under high temperature and high humidity is inferior to the evaluation in the image formation test under low temperature and low humidity. This is because it becomes more susceptible to the influence of discharge products.

1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to an embodiment. 1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to an embodiment. 1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to an embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other embodiment. (A) thru | or (C) is a figure which shows the image pattern used for image evaluation, respectively. It is IR spectrum of a product (A-4). It is IR spectrum of a product (A-17). It is IR spectrum of a product (A-18).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Undercoat layer 2 Charge generation layer 3 Charge transport layer 4 Conductive substrate 5 Protective layer 6 Single layer type photosensitive layer (charge generation / charge transport layer)
7A, 7B, 7C, 7 Electrophotographic photosensitive member 8 Charging device 9 Exposure device 11 Developing device 13 Cleaning device 14 Lubricant 40 Transfer device 50 Intermediate transfer member 100 Image forming device 120 Image forming device 300 Process cartridge

Claims (10)

At least a conductive substrate and a photosensitive layer provided on the conductive substrate;
Two types of thermal polymerization initiators, wherein the outermost surface layer has at least one compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule, and a 10-hour half-life temperature difference of 20 ° C. or more. An electrophotographic photosensitive member comprising a cured film of a composition containing two or more thermal polymerization initiators (b).   The electrophotographic photoreceptor according to claim 1, wherein the cured film is obtained by curing the composition with heat.   The composition further comprises a monomer or oligomer (c) having no charge transport property that reacts with the compound (a) having a charge transport skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to claim 1 or 2.   The composition according to any one of claims 1 to 3, wherein the composition further comprises a polymer (d) that does not react with the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to any one of the above.   The composition according to any one of claims 1 to 4, wherein the composition further comprises a polymer (e) that reacts with the compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule. The electrophotographic photosensitive member according to any one of the above.   The compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule is a compound (a ′) having a triphenylamine skeleton and four or more methacryloyl groups in the same molecule. The electrophotographic photosensitive member according to any one of claims 1 to 5. The electron according to claim 6, wherein the compound (a ') having a triphenylamine skeleton and four or more methacryloyl groups in the same molecule is a compound represented by the following general formula (A). Photoconductor.

[In General Formula (A), Ar ^{1 to} Ar ⁴ each independently represent a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted arylene group. , D represents — (CH ₂ ) _d — (O—CH ₂ —CH ₂ ) _e —O—CO—C (CH ₃ ) ═CH ₂ , and c1 to c5 are each independently 0, 1 or 2 , K represents 0 or 1, d represents an integer of 1 to 5, e represents 0 or 1, and the total number of D is 4 or more. ] At least one compound (a) having a charge transporting skeleton and an acryloyl group or a methacryloyl group in the same molecule, and two or more kinds including two kinds of thermal polymerization initiators having a 10-hour half-life temperature difference of 20 ° C. or more A coating liquid comprising a composition containing the thermal polymerization initiator (b) is applied to the surface to be coated to form a coating film, and then the coating film is cured by heat to obtain an outermost surface layer. A process for producing an electrophotographic photosensitive member, comprising: The electrophotographic photosensitive member according to any one of claims 1 to 7 , charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image formed on the electrophotographic photosensitive member are developed with toner. And a developing unit and at least one unit selected from the group consisting of a toner removing unit that removes toner remaining on the surface of the electrophotographic photosensitive member, and is detachable from the image forming apparatus. Process cartridge. An electrophotographic photosensitive member according to any one of claims 1 to 7, the electrophotographic photosensitive member and charging means for charging a charged electrostatic latent to form an electrostatic latent image on said electrophotographic photosensitive member An image unit; a developing unit that develops an electrostatic latent image formed on the electrophotographic photosensitive member with toner to form a toner image; and a transfer unit that transfers the toner image to a transfer target. An image forming apparatus.

Images