JP2006011307A - Electrophotographic photoreceptor, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having superior wear resistance and heat resistance, and an image forming apparatus and a process cartridge that uses the electrophotographic photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor contains a copolymer of compounds represented by Formulae (I) and (II) or by a mixture of homopolymers of the compounds. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  An electrophotographic image forming apparatus is equipped with an electrophotographic photosensitive member (hereinafter, referred to as “photosensitive member” in some cases) in which a functional layer such as a photosensitive layer is formed on a conductive support.

  Conventionally, polycarbonate has been widely used as a binder resin as a constituent material of such a functional layer. Usually, when a binder resin is used as a constituent material, the functional layer is formed by a coating method such as a dip coating method. Among polycarbonates, in particular, bisphenol Z-type polycarbonate has a high solubility in various organic solvents, so it is relatively easy to prepare a coating solution, and further, mechanical strength and electrical characteristics are also relatively good. It was the main binder resin used in the above (for example, see Patent Document 1).

  An electrophotographic image forming apparatus is provided with a cleaning member that removes deposits and residual toner on the surface of a photoreceptor in an electrophotographic process. In addition, due to the repeated electrophotographic process, the temperature in the image forming apparatus becomes relatively high. For this reason, the photoreceptor is required to have a certain degree of wear resistance and heat resistance.

  Under such circumstances, for the purpose of improving the wear resistance and heat resistance of the photoreceptor, for example, bisphenol A type polycarbonate, various modified polycarbonates, aromatic polycyclic polycarbonate, and various polyarylates are used for electrophotographic photoreceptors. There is also a report to be applied to a binder resin (see, for example, Patent Documents 2 to 4).

JP-A-1-246580 JP-A-6-75391 JP-A-8-123049 JP 2003-43817 A

  In recent years, electrophotographic image forming apparatuses have been required to have high image quality equivalent to that of printing. For this reason, the contact pressure of the cleaning member to the photoconductor is strengthened, and the photoconductor is placed in a condition where wear tends to proceed. ing. In addition, with the miniaturization of printers, the photoconductor and the heat generating part such as a fuser are arranged at relatively close positions, and further improvement in heat resistance is required for the photoconductor.

  However, the electrophotographic photosensitive member using the conventional binder resin is still insufficient in satisfying the above-described requirements for its wear resistance and heat resistance.

  The present invention has been made in view of the above-described problems of the prior art, and has an electrophotographic photosensitive member having excellent wear resistance and heat resistance, and an image forming apparatus and a process cartridge using the electrophotographic photosensitive member. The purpose is to provide.

  In order to achieve the above-mentioned problems, the present inventor has eagerly studied to obtain a binder resin having excellent characteristics in terms of wear resistance and heat resistance as a binder resin for an electrophotographic photoreceptor. As a result, it has been found that a polymer having a biphenyl skeleton has a rigid molecular structure and has extremely high mechanical strength and heat resistance.

  However, since such a polymer has a biphenyl skeleton, it has high crystallinity and extremely poor solubility in an organic solvent. Therefore, it has been difficult to apply as a binder resin for an electrophotographic photosensitive member.

  Therefore, as a result of further intensive studies, the present inventors have found that a resin containing both a specific structural unit having a biphenyl skeleton and a specific structural unit having high flexibility is excellent as a binder resin for an electrophotographic photoreceptor, and It has been found that the above problems can be solved by an electrophotographic photoreceptor using the resin, and the present invention has been completed.

［上記式中、Ａ^１及びＡ^２はそれぞれ独立に２価の置換基を表し、Ｒ^１、Ｒ^２、Ｒ^５及びＲ^６はそれぞれ独立にアルキレン基を表し、Ｒ^３、Ｒ^４及びＲ^７はそれぞれ独立に置換若しくは無置換のアルキル基、置換若しくは無置換のアリール基、ケイ素原子を含む置換基又はフッ素原子を含む置換基を表し、ａ、ｂ及びｃは０〜４の整数を表す。但し、ｃが２以上の整数である場合には、それらの置換基は互いに結合して環を形成してもよい。］ That is, the electrophotographic photosensitive member of the present invention includes a conductive support and a photosensitive layer formed on the conductive support, and the photosensitive layer is a structural unit represented by the following general formula (I): And a copolymer having a structural unit represented by the following general formula (II) or (III), or a homopolymer having a structural unit represented by the following general formula (I) and the following general formula (II) or It contains a mixture with a homopolymer having the structural unit represented by (III).

[In the above formula, A ¹ and A ² each independently represent a divalent substituent, R ¹ , R ² , R ⁵ and R ⁶ each independently represent an alkylene group, and R ³ , R ⁴ and R ⁷ Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituent containing a silicon atom or a substituent containing a fluorine atom, and a, b and c each represents an integer of 0 to 4. However, when c is an integer of 2 or more, these substituents may be bonded to each other to form a ring. ]

  In the present invention, an electrophotographic photosensitive member having excellent wear resistance and heat resistance can be obtained by incorporating the specific copolymer or the mixture of the specific homopolymers in the photosensitive layer.

  The reason why the above-described effect can be obtained by the present invention is not necessarily clear, but the present inventor presumes as follows. That is, since the polymer having the structural unit represented by the general formula (I) has a biphenyl skeleton, the molecular chain is arranged with high regularity, so that the solubility in an organic solvent is poor. Here, when the structural unit represented by the general formula (II) or (III) having high flexibility coexists in the same molecule or in the same mixture, high regularity derived from the biphenyl skeleton is maintained to some extent. It is thought that bending occurs partially. As a result, while maintaining the excellent mechanical strength and heat resistance derived from the biphenyl skeleton, the solubility in organic solvents can be improved, and the specific polymer having the biphenyl skeleton is used as a binder resin for an electrophotographic photosensitive member. It is considered that an electrophotographic photoreceptor having excellent wear resistance and heat resistance can be obtained.

  Further, in the present invention, the copolymer and homopolymer used are those in which the burden on the environment is reduced, and the amount of the organic solvent used in forming the functional layer by the coating method is the same as the conventional amount. It becomes possible to reduce compared with the case where binder resin is used. Therefore, the electrophotographic photoreceptor of the present invention is also preferable from the viewpoint of environment.

［上記式中、Ａ^１及びＡ^２はそれぞれ独立に２価の置換基を表し、Ｒ^１、Ｒ^２、Ｒ^５及びＲ^６はそれぞれ独立にアルキレン基を表し、Ｒ^３、Ｒ^４及びＲ^７はそれぞれ独立に置換若しくは無置換のアルキル基、置換若しくは無置換のアリール基、ケイ素原子を含む置換基又はフッ素原子を含む置換基を表し、ａ、ｂ及びｃは０〜４の整数を表す。但し、ｃが２以上の整数である場合には、それらの置換基は互いに結合して環を形成してもよい。］ In the electrophotographic photoreceptor of the present invention, the copolymer has a structural unit represented by the following general formula (II-1) or a structural unit represented by the following general formula (III-1). Is preferred.

[In the above formula, A ¹ and A ² each independently represent a divalent substituent, R ¹ , R ² , R ⁵ and R ⁶ each independently represent an alkylene group, and R ³ , R ⁴ and R ⁷ Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituent containing a silicon atom or a substituent containing a fluorine atom, and a, b and c each represents an integer of 0 to 4. However, when c is an integer of 2 or more, these substituents may be bonded to each other to form a ring. ]

  In the copolymer, the specific structural unit having the biphenyl skeleton and the specific structural unit having high flexibility are adjacently bonded to each other, so that one molecular chain is bent while maintaining a certain degree of rigidity. The solubility in an organic solvent can be further improved while maintaining the mechanical strength and heat resistance obtained by the specific structural unit having the biphenyl skeleton.

  In the electrophotographic photoreceptor of the present invention, the copolymer is preferably a random copolymer. In this case, the regular arrangement of molecular chains derived from the biphenyl skeleton can be further disturbed, and the solubility in organic solvents can be further improved.

［上記式中、Ｘ及びＹはそれぞれ独立に２価の置換基を表す。］ In the electrophotographic photoreceptor of the present invention, it is preferable that the copolymer further has a structural unit represented by the following general formula (IV).

[In the above formula, X and Y each independently represent a divalent substituent. ]

  When the specific copolymer is synthesized, the presence of a compound that is a raw material for the specific structural unit makes it possible to synthesize a specific copolymer having desired characteristics more easily.

  In the electrophotographic photoreceptor of the present invention, the copolymer and the homopolymer preferably have a weight average molecular weight of 30,000 to 1,000,000. The weight average molecular weight is a value in terms of styrene. When the weight average molecular weight satisfies the above range, excellent wear resistance and heat resistance are sufficiently exhibited.

  The electrophotographic photoreceptor of the present invention is a copolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) or (III), or the general In a mixture of a homopolymer having a structural unit represented by the formula (I) and a homopolymer having a structural unit represented by the general formula (II) or (III), the mixture is represented by the general formula (I). It is preferable that the molar ratio of the structural unit represented by the said general formula (II) or the structural unit represented by (III) is 1: 9-9: 1. When the molar ratio satisfies the above range, the solubility in an organic solvent is particularly excellent, and the excellent wear resistance and heat resistance are sufficiently exhibited.

  Moreover, as a suitable structure of the electrophotographic photoreceptor of the present invention, there is the following structure (i) or (ii). That is, (i) the photosensitive layer includes a charge generation layer and a charge transport layer, and the charge transport layer includes the structural unit represented by the general formula (I) and the general formula (II) or (III). Or a homopolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) or (III). A composition containing a mixture with a homopolymer.

  (Ii) The photosensitive layer has a protective layer on the side farthest from the conductive support, and the protective layer is composed of the structural unit represented by the general formula (I) and the general formula (II) or (III Or a homopolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) or (III). The structure containing the mixture with the homopolymer which has.

  The image forming apparatus of the present invention includes the electrophotographic photosensitive member of the present invention, a charging device for charging the electrophotographic photosensitive member, and exposure for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. And a developing device that develops the electrostatic latent image to form a toner image, and a transfer device that transfers the toner image to a transfer medium. Since the image forming apparatus of the present invention includes the electrophotographic photosensitive member of the present invention, good image quality can be obtained over a long period of time.

  The process cartridge of the present invention includes an electrophotographic photosensitive member of the present invention, a charging device for charging the electrophotographic photosensitive member, and an exposure device for forming an electrostatic latent image by exposing the charged electrophotographic photosensitive member. And a developing device for developing the electrostatic latent image to form a toner image, and at least one selected from a cleaning device for cleaning the electrophotographic photosensitive member. Since the process cartridge of the present invention includes the electrophotographic photosensitive member of the present invention, good image quality can be obtained over a long period of time.

  According to the present invention, an electrophotographic photosensitive member having excellent wear resistance and heat resistance, and an image forming apparatus and a process cartridge capable of obtaining a good image quality over a long period of time are provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention comprises a copolymer having, in its photosensitive layer, a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II) or (III): Or the mixture of the homopolymer which has a structural unit represented by the following general formula (I), and the homopolymer which has a structural unit represented by the following general formula (II) or (III) is contained.

Here, in the above formula, A ¹ and A ² each independently represent a divalent substituent, R ¹ , R ² , R ⁵ and R ⁶ each independently represent an alkylene group, R ³ , R ⁴ and R ⁷ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituent containing a silicon atom or a substituent containing a fluorine atom, and a, b and c are each an integer of 0 to 4. To express. However, when c is an integer of 2 or more, these substituents may be bonded to each other to form a ring.

Examples of the divalent substituent represented by A ¹ and A ² include a substituted or unsubstituted alkylene group and a substituted or unsubstituted arylene group. As said alkylene group, a C1-C10 alkylene group is preferable. As said arylene group, a C6-C20 arylene group is more preferable. In addition, the substituent for the alkylene group or arylene group is not particularly limited, and examples thereof include an alkyl group, an alkyl group in which a hydrogen atom is substituted with a fluorine atom, and an aryl group.

More specific examples of the divalent substituent represented by A ¹ and A ² include those represented by the following (A-1) to (A-33).

As an alkylene group represented by said R < ¹ >, R < ² >, R < ⁵ > and R < ⁶ >, the said C1-C10 alkylene group is preferable and a C1-C4 alkylene group is more preferable.

As an alkyl group represented by said R < ³ >, R < ⁴ > and R < ⁷ >, a C1-C10 alkyl group is preferable. Moreover, as an aryl group, a C6-C20 aryl group is preferable. Examples of the substituent containing a silicon atom include those in which part or all of the carbon atoms of the above-described alkyl group such as a silyl group and a silyldisiranyl group are substituted with a silicon atom. Moreover, as a substituent containing a fluorine atom, what substituted a part or all of the hydrogen atom of the alkyl group mentioned above by the fluorine atom is mentioned, for example.

When c is an integer of 2 or more, the substituents represented by R ³ , R ⁴ and R ⁷ may be bonded to each other to form a ring. In this case, the ring formed may be aliphatic, aromatic, or heterocyclic. In particular, in the structural unit represented by the general formula (III), c is 2 and is preferably a naphthylene group.

More specifically, as the structural unit represented by the general formula (I), A ¹ , R ¹ , R ² , R ³ , R ⁴ , a and b are the following (1-1) to (1 The combination represented by -11) is mentioned. In the table below, —C ₆ H ₅ represents a phenyl group.

Further, as the structural unit represented by the general formula (II) or (III), more specifically, A ² , R ⁵ , R ⁶ , R ⁷ and c are represented by the following (2-1) to ( The combination represented by 2-11) is mentioned.

  It is preferable that the copolymer has a structural unit represented by the following general formula (II-1) or a structural unit represented by the following general formula (III-1).

Here, in the above formula, A ¹ , A ² , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , a, b and c are the above general formulas (I), ( It is the same as A ¹ , A ² , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , a, b and c described in (II) and (III). In the above general formulas (II-1) and (III-1), A ¹ , A ² , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , a, b and c The combinations include the combinations represented by the above (1-1) to (1-11) and (2-1) to (2-10), and (1-1), (2-1), (1 -2) and (2-2) are preferably combined. Note that (1-11) is preferably combined with (2-10).

  Here, in the said copolymer and the mixture of a homopolymer, the copolymer which has the said specific structural unit is preferable at the point of the solubility to an organic solvent. The copolymer may be a block copolymer or a random copolymer, but is preferably a random copolymer.

  Moreover, it is preferable that the said copolymer further has a structural unit represented by the following general formula (IV).

  Here, in said formula, X and Y represent a bivalent substituent each independently. More specific examples of X and Y include a substituted or unsubstituted alkylene group and a substituted or unsubstituted arylene group. As said alkylene group, a C1-C10 alkylene group is preferable. As said arylene group, a C6-C20 arylene group is more preferable. In addition, the substituent for the alkylene group or arylene group is not particularly limited, and examples thereof include an alkyl group, an alkyl group in which a hydrogen atom is substituted with a fluorine atom, and an aryl group.

  The weight average molecular weight of the copolymer and the homopolymer is preferably 30,000 to 1,000,000, and more preferably 40,000 to 200,000. The weight average molecular weight is a value in terms of styrene. When the weight average molecular weight is less than 30,000, the mechanical strength tends to be insufficient. On the other hand, if it exceeds 1,000,000, the solubility in an organic solvent tends to be insufficient and coating molding tends to be difficult.

  Further, a copolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) or (III), or a structure represented by the general formula (I) In a mixture of a homopolymer having a unit and a homopolymer having a structural unit represented by the general formula (II) or (III), the structural unit represented by the general formula (I) and the general formula ( The molar ratio with the structural unit represented by II) or (III) is preferably 1: 9 to 9: 1, and more preferably 3: 7 to 8: 2. When this molar ratio is less than 1: 9, the effects of high mechanical strength and heat resistance due to the structural unit represented by the general formula (I) tend to be insufficient. On the other hand, if it exceeds 9: 1, the solubility effect in the organic solvent due to the structural unit represented by the general formula (II) or (III) tends to be insufficient.

  A copolymer having the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) or (III) described above, or the general formula (I) or (II). Or the homopolymer which has a structural unit represented by (III) can be manufactured by a well-known method. However, a copolymer composed only of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) or (III) is synthesized by the method described below. It is preferable to do.

  That is, first, a dicarboxylic acid derivative and a diol are prepared as raw materials for a copolymer having the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) or (III). To do. The raw material dicarboxylic acid derivative and diol are put into the polymerization apparatus at a ratio of dicarboxylic acid derivative: diol = 1: 1 to 1: 4. Further, a known transesterification catalyst such as metal acetate, metal oxide, titanate or the like is further added to the raw material in an amount of about 1 to 1000 ppm.

  Depending on the structure of the target copolymer, the inside of the polymerization apparatus is heated to 140 to 180 ° C., and the stirring is started when the raw material is dissolved. Next, the temperature in the polymerization apparatus is increased at a temperature increase rate of 30 ° C./hour, and water or alcohol to be distilled off is measured. When the temperature in the apparatus reaches 220 to 250 ° C., the temperature rise is stopped and this temperature is maintained. When the distilled water or alcohol reaches 90% or more of the theoretical amount, the transesterification reaction is terminated.

  Here, about 1 to 1000 ppm of a polymerization catalyst such as metal oxide or titanate is added to the raw material, stirring is continued, and the inside of the polymerization apparatus is gradually depressurized. In addition, the temperature is increased at a rate of temperature increase of 60 ° C./hour simultaneously with the pressure reduction. In 1 to 3 hours, the pressure in the polymerization apparatus is set to 10 Pa or less, the temperature is set to 260 to 300 ° C., and this state is maintained. When the stirring torque reaches a predetermined value, the polymerization reaction is terminated and the desired copolymer is obtained. Thereafter, the inside of the polymerization apparatus is slightly pressurized, and the obtained copolymer is extruded in a strand shape, passed through a cooling pool, and then pelletized with a cutter.

  Next, the configuration of the electrophotographic photosensitive member of the present invention will be described. The electrophotographic photoreceptor of the present invention comprises a photosensitive layer on a conductive support. Such a photosensitive layer is a single-layer type photosensitive layer containing a charge generation material and a charge transport material in the same layer, or a layer containing a charge generation material (charge generation layer) and a layer containing a charge transport material (charge transport). Any of the function-separated type photosensitive layers provided separately.

  When the photosensitive layer includes a charge generation layer and a charge transport layer, the charge transport layer is represented by the structural unit represented by the general formula (I) and the general formula (II) or (III). Or a homopolymer having a structural unit represented by the general formula (II) or (III) and a homopolymer having a structural unit represented by the general formula (I). It is preferable to contain a mixture with coalescence.

  When the photosensitive layer is provided with a protective layer on the side farthest from the conductive support, the protective layer is a structural unit represented by the general formula (I) and the general formula (II) or (III). Or a homopolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) or (III). It is preferable to contain a mixture with a homopolymer.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the electrophotographic photosensitive member of the present invention. As shown in FIG. 1, the electrophotographic photosensitive member 1 includes a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 has a structure in which a charge generation layer 5 and a charge transport layer 6 are laminated in this order on a conductive support 2.

  The electrophotographic photoreceptor 1 of FIG. 1 contains the above-mentioned copolymer or a mixture of two types of homopolymers in the charge transport layer 6.

Hereinafter, each element of the electrophotographic photoreceptor 1 will be described.
The conductive support 2 is not particularly limited, and for example, a metal drum such as aluminum, copper, iron, zinc, or nickel can be used. Also, by depositing a metal such as aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, copper-indium on a substrate such as a polymer sheet, paper, plastic, glass, etc. Conductive treatment: Conductive treatment by depositing a conductive metal compound such as indium oxide and tin oxide or laminating a metal foil; and carbon black, indium oxide, tin oxide-antimony oxide powder, Examples thereof include a metal powder, copper iodide, etc. dispersed in a binder resin and subjected to a conductive treatment by coating on the substrate. These shapes can be any shape such as a drum shape, a sheet shape, and a plate shape.

  Here, when a metal pipe substrate is used as the conductive support 2, the surface thereof may be a raw tube, but in advance, mirror cutting, etching, anodizing, rough cutting, centerless grinding, sandblasting, wet It is preferable to perform processing such as honing and coloring. By performing the surface treatment and roughening the surface of the base material, it is possible to prevent grain-like density spots due to interference light in the photoconductor that may occur when a coherent light source such as a laser beam is used. .

  Next, the charge generation layer 5 will be described. The charge generation layer 5 includes a charge generation material, and preferably includes at least a charge generation material and a binder resin.

  The charge generation material is not particularly limited as long as it has a charge generation function, and a known material can be used. Specific examples include azo pigments such as bisazo and trisazo, condensed ring aromatic pigments such as dibromoanthanthrone, perylene pigments, pyrrolopyrrole pigments, phthalocyanine pigments, and selenium.

  Among these, phthalocyanine pigments are preferable, and among these, hydroxygallium phthalocyanine pigments are particularly preferable.

  Further, as hydroxygallium phthalocyanine, hydroxygallium phthalocyanine having an absorption maximum at 810 to 839 nm in the spectral absorption spectrum is excellent in dispersibility in the charge generation layer 5 and has high photosensitivity and high image quality such as fogging. This is particularly preferable because image quality can be realized.

  The binder resin is not particularly limited. Specifically, polyvinyl butyral resin, polyarylate resin, polyester resin, polycarbonate resin, phenoxy resin, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin , Polyvinylpyrrolidone resin, polystyrene resin, vinyl chloride-vinyl acetate copolymer, or a copolymer thereof. Moreover, you may use the copolymer concerning this invention, a homopolymer, or those mixtures.

  Among these, polyvinyl butyral resin, a copolymer of polystyrene and acrylic resin, and vinyl chloride-vinyl acetate copolymer are preferable from the viewpoint of dispersibility of the charge generating material.

  The charge generation layer 5 is formed using a charge generation layer forming coating solution in which a charge generation material and a binder resin are added to a predetermined solvent. In addition, when the charge generation layer 5 includes only a charge generation material, the charge generation layer 5 is formed by an evaporation method.

  Specific examples of the solvent include methanol, ethanol, n-butanol, benzyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, toluene, xylene, chlorobenzene, Examples include dimethylformamide, dimethylacetamide, and water. These may be used singly or as a mixture of two or more.

  When mixing and dispersing a charge generating material and a binder resin in such a solvent, sand mill, colloid mill, attritor, dyno mill, jet mill, coball mill, roll mill, ultrasonic disperser, gorin homogenizer, microfluidizer, Ultima Iser, milder, etc. can be used.

  In addition, when applying the coating solution for forming the charge generation layer, blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. should be adopted. Can do. Then, the charge generation layer 5 is formed by applying a coating solution on the conductive support 2 and drying it.

  The film thickness of the charge generation layer 5 is preferably 0.05 to 5 μm and more preferably 0.1 to 1 μm in order to obtain good electrical characteristics and image quality. When the thickness of the charge generation layer 5 is less than 0.05 μm, it tends to be difficult to obtain sufficient sensitivity. On the other hand, when the film thickness of the charge generation layer 5 exceeds 5 μm, there is a tendency that adverse effects such as defective charging are likely to occur.

  When another layer such as the charge transport layer 6 is further formed on the charge generation layer 5, the charge generation layer 5 is not dissolved or swollen by the solvent used in the coating solution. A combination of the binder resin of the charge generation layer 5 and the solvent of the coating solution applied on the charge generation layer 5 is appropriately selected. The binder resin of the charge generation layer 5 and the binder resin of the charge transport layer 6 to be described later are preferably used in combination with ones whose refractive indexes are close to each other. The difference is preferably 1 or less. When a binder resin having a refractive index close to each other is used in combination, light reflection at the interface between the charge generation layer 5 and the charge transport layer 6 is suppressed, and the interference fringe prevention effect tends to be improved.

  Next, the charge transport layer 6 will be described. The charge transport layer 6 includes at least a charge transport material and a binder resin. In addition, as binder resin, the copolymer and homopolymer mixture concerning this invention mentioned above are contained.

  The charge transport material is not particularly limited as long as it has a function of transporting charges. Specifically, pyrazoline derivatives, aromatic tertiary amino compounds, aromatic tertiary diamino compounds, 1,2,4-triazine derivatives, hydrazone derivatives, quinazoline derivatives, benzofuran derivatives, α-stilbene derivatives, enamine derivatives, Hole transport materials such as carbazole derivatives and poly-N-vinylcarbazole derivatives, electrons such as quinone compounds, tetracyanoxydimethane compounds, fluorenone compounds, oxadiazole compounds, xanthone compounds, thiophene compounds and diphenoquinone compounds Examples thereof include transportable compounds or polymer compounds containing these structures. These compounds may be used alone or in combination of two or more.

  Among these, the compounds represented by the general formulas (V) to (VII) are particularly preferable in terms of high mobility.

Here, in the above formula ^{(V), Ar 1, Ar} 2 each independently represent a substituted or unsubstituted aryl group, d is an integer of 0 to 2. Such an aryl group is preferably an aryl group having 6 to 20 carbon atoms. The aryl group is substituted with an alkyl group (preferably an alkyl group having 1 to 5 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), or an alkyl group having 1 to 3 carbon atoms. A substituted amino group and a halogen atom are preferred.

In the formula (VI), R ¹¹ and R ¹² are each independently an alkyl group (preferably an alkyl group having 1 to 5 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), or a halogen atom. Represents. R ^{13 to} R ¹⁶ are each independently an alkyl group (preferably an alkyl group having 1 to 5 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), or an alkyl group having 1 to 2 carbon atoms. It represents a substituted amino group, a substituted or unsubstituted aryl group, or a substituent represented by the following formulas (VI-1) and (VI-2). e to h each independently represent an integer of 0 to 2.

Here, in the formula (VI-1), R ^{31 to} R ³³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. In the formula (VI-2), Ar ³ and Ar ⁴ each independently represent a substituted or unsubstituted aryl group.

In the above formula (VII), R ¹⁷ is a hydrogen atom, an alkyl group (preferably an alkyl group having 1 to 5 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), a substituted or unsubstituted group. An aryl group or a substituent represented by the above formula (VI-1) or (VI-2) is represented. R ^{18 to} R ²¹ are each independently a hydrogen atom, an alkyl group (preferably an alkyl group having 1 to 5 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 5 carbon atoms), or an alkyl group having 1 to 2 carbon atoms. Represents a substituted amino group substituted with or a substituted or unsubstituted aryl group. Moreover, k1-k5 represents the integer of 1-4.

  The binder resin contains the above-described copolymer and homopolymer mixture according to the present invention, but may be used in combination with other commonly used binder resins. Examples of the other binder resin include those similar to those exemplified in the charge generation layer 5.

  The charge transport layer 6 is formed using a charge transport layer forming coating solution in which a charge transport material and a binder resin are added to a predetermined solvent. The blending ratio (mass ratio) of the binder resin and the charge transport material in such a coating liquid can be arbitrarily set in consideration of electrical characteristics and film strength.

  Examples of the solvent used in the charge transport layer forming coating solution include ordinary organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These can be used individually by 1 type or in mixture of 2 or more types. When the charge transport material and the binder resin are mixed and dispersed in such a solvent, the known means described for the charge generation layer 5 can be used.

  As a coating method for forming the charge transport layer 6, 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. be able to. Then, the charge transport layer 6 is formed by applying a coating solution on the charge generation layer 5 and drying it.

  The thickness of the charge transport layer 6 is preferably 5 to 50 μm, and more preferably 10 to 35 μm.

  FIG. 2 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. As shown in FIG. 2, the electrophotographic photoreceptor 1 a is composed of a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 has a structure in which an undercoat layer 4, a charge generation layer 5, and a charge transport layer 6 are laminated in this order on a conductive support 2. The electrophotographic photoreceptor 1 a has the same configuration as the electrophotographic photoreceptor 1 except that the photosensitive layer 3 includes the undercoat layer 4.

  Hereinafter, the undercoat layer 4 will be described. The undercoat layer 4 has a function of preventing the injection of charges from the conductive support 2 to the photosensitive layer 3 when the photosensitive layer 3 is charged. The undercoat layer 4 also functions as an adhesive layer that allows the photosensitive layer 3 to be adhered and held integrally with the conductive support 2. Further, the undercoat layer 4 has a function of preventing light reflection of the conductive support 2.

  The undercoat layer 4 includes a binder resin, and may further include an organic compound or inorganic compound powder, an electron transporting material, or the like.

  Examples of the binder resin include acetal resins such as polyvinyl 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. -High molecular resin compounds such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin.

  The undercoat layer 4 may be configured to contain a known material such as a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound, a titanium alkoxide compound, an organic titanium compound, or a silane coupling agent. And these compounds and the binder resin mentioned above can be used individually by 1 type or as a mixture or polycondensate of several compounds.

  Among these, the zirconium chelate compound and the silane coupling agent are excellent in performance, such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

  Examples of the silane coupling agent include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidoxy. Propyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) ) -Γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

  Particularly preferred silane coupling agents are vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N -Phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane and the like.

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

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

  In the undercoat layer 4, various organic compound fine powders or inorganic compound fine powders can be added for the purpose of improving electrical characteristics and light scattering properties. In particular, white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, lithopone, and inorganic pigments such as alumina, calcium carbonate, barium sulfate, polytetrafluoroethylene resin particles, benzoguanamine resin particles, Styrene resin particles and the like are effective. The added fine powder preferably has a particle size of 0.01 to 2 μm. The fine powder is added as necessary, but the addition amount is preferably 10 to 90% by mass, and 30 to 80% by mass with respect to the total mass of the solid content of the undercoat layer 4. More preferably. Among these, zinc oxide or titanium oxide having particularly high electron mobility is particularly preferable.

  In addition, it is also effective in the undercoat layer 4 to contain the electron transporting substance, the electron transporting pigment and the like described above from the viewpoint of lowering the residual potential and environmental stability.

  The undercoat layer 4 is formed using an undercoat layer forming coating solution containing the above-described constituent materials. When preparing the coating liquid for forming the undercoat layer, when adding a fine powdery substance, it is added to a solution in which the resin component is dissolved and dispersed.

  As the dispersion treatment method, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. And the undercoat layer 4 forms by apply | coating the obtained coating liquid on the electroconductive support body 2, and making it dry.

  As a coating method at this time, usual methods 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, a curtain coating method, and the like can be used.

  The thickness of the undercoat layer 4 thus formed is preferably 0.01 to 30 μm, and more preferably 0.05 to 25 μm.

  FIG. 3 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. As shown in FIG. 3, the electrophotographic photoreceptor 1 b is composed of a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 has a structure in which a charge generation layer 5, a charge transport layer 6, and a protective layer 7 are laminated on the conductive support 2 in this order. The electrophotographic photoreceptor 1b has the same configuration as the electrophotographic photoreceptor 1 except that the photosensitive layer 3 includes the protective layer 7.

  The electrophotographic photoreceptor 1b of FIG. 3 contains the above-described copolymer or homopolymer mixture in the charge transport layer 6 and / or the protective layer 7 described above.

  The protective layer 7 is used to prevent chemical change of the charge transport layer 6 during charging of the electrophotographic photoreceptor 1 c or to further improve the mechanical strength of the photosensitive layer 3.

  The protective layer 7 includes a conductive material and a binder resin. The conductive material is not particularly limited, and examples thereof include metallocene compounds such as N, N′-dimethylferrocene, N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[ Aromatic amine compounds such as 1,1′-biphenyl] -4,4′-diamine, molybdenum oxide, tungsten oxide, antimony oxide, tin oxide, titanium oxide, indium oxide, tin oxide and antimony, barium sulfate and antimony oxide A solid solution carrier, a mixture of the above metal oxides, a mixture of the above metal oxides in a single particle of titanium oxide, tin oxide, zinc oxide or barium sulfate, or titanium oxide, tin oxide, zinc oxide, Or what coat | covered said metal oxide in the single particle | grains of barium sulfate is mentioned.

  Examples of the binder resin include a copolymer or a mixture of homopolymers according to the present invention. Other binder resins include polyamide resin, polyvinyl acetal resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, polyimide resin, polyamideimide resin, etc. These known resins are used. These can also be used by cross-linking each other as necessary.

The protective layer 7 preferably has a charge transporting property and a crosslinked structure, and more preferably a crosslinked film having a charge transporting property, from the viewpoint of strength, electrical characteristics, image quality maintenance, and the like. As such a crosslinked film, one made of a siloxane resin is more preferred, and one having a structure represented by the general formula (X) is particularly preferred.
G-D-F (VIII)
Here, in the above formula, G represents an inorganic glassy network subgroup, D represents a flexible organic subunit, and F represents a charge transporting subunit.

  Examples of charge transporting subunits include triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, quinone compounds, and fluorenone compounds. , Xanthone compounds, benzophenone compounds, cyanovinyl compounds, ethylene compounds, and the like. Among these, triarylamine compounds are preferred in combination with the charge transport layer 6 of the electrophotographic photosensitive member of the present invention.

  Moreover, the inorganic glassy network subgroup includes, for example, a structure having a reactive Si group. This causes a cross-linking reaction with each other to form a three-dimensional Si—O—Si bond.

  Moreover, a flexible organic subunit gives moderate flexibility to a hard but brittle inorganic glassy network, and specific examples include an alkylene straight chain and an unsaturated hydrocarbon group.

  The protective layer 7 is formed using a coating liquid for forming a protective layer containing the above-described constituent materials. As the solvent used in this coating solution, a common organic solvent such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like can be used alone or in admixture of two or more, but this coating solution is applied as much as possible. It is preferable to use a solvent that hardly dissolves the lower layer (in the electrophotographic photoreceptor 1b, the charge transport layer 6).

  As a coating method for forming the protective layer 7, usual methods 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, and a curtain coating method are used. be able to.

  The film thickness of the protective layer 7 thus formed is preferably 1 to 20 μm, and more preferably 2 to 10 μm.

  The preferred embodiment of the electrophotographic photoreceptor of the present invention has been described in detail above, but the electrophotographic photoreceptor of the present invention is not limited to the above embodiment. For example, as in the electrophotographic photoreceptor 1c shown in FIG. 4, the photosensitive layer 3 includes an undercoat layer 4, a charge generation layer 5, a charge transport layer 6 and a protective layer 7 in this order on the conductive support 2. You may have a laminated structure. Moreover, the stacking order of the charge generation layer 5 and the charge transport layer 6 may be reversed.

  Usually, in order to form the protective layer 7, the charge transport layer 6 needs to have heat resistance and mechanical strength sufficient to withstand the hardening of the protective layer 7. Cracks associated with shrinkage occur. Since the charge transport layer 6 containing a copolymer or a mixture of homopolymers according to the present invention has high heat resistance and high opportunity strength, such problems are suppressed.

  In the electrophotographic photoreceptors 1, 1 a, 1 b, and 1 c of the above embodiment, the case where the photosensitive layer 3 is a function separation type has been described. However, the electrophotographic photoreceptor of the present invention is not a function separation type. For example, it may be a single layer type as in the electrophotographic photoreceptor 1d shown in FIG. Also in this case, the photosensitive layer may be constituted by providing the undercoat layer 4 between the conductive support 2 and the single-layer type photosensitive layer 8, and the protective layer 7 is provided on the single-layer type photosensitive layer. The photosensitive layer may be provided, and may further have both the undercoat layer 4 and the protective layer 7.

  The electrophotographic photosensitive member of the present invention includes an image forming apparatus such as a laser beam printer, a digital copying machine, an LED printer, and a laser facsimile that emits near-infrared light or visible light, and a process cartridge provided in such an image forming apparatus. Can be mounted on. The electrophotographic photoreceptor of the present invention can be used in combination with a one-component or two-component regular developer or reversal developer. In addition, the electrophotographic photosensitive member of the present invention is mounted on a contact charging type image forming apparatus using a charging roller or a charging brush, and good characteristics with less current leakage can be obtained.

  The electrophotographic photoreceptor of the present invention is suitable for use in an image forming apparatus using a light source having an exposure wavelength in the ultraviolet range, specifically 380 to 500 nm. In particular, when a short wavelength laser beam or LED in the above wavelength range is used as an exposure light source, since it is high energy, the temperature of the surface of the photoconductor becomes high at the time of irradiation, and a normal photoconductor is susceptible to thermal degradation. Since the photoconductor of the present invention has extremely high heat resistance, it does not cause thermal degradation, is excellent in thermal stability and durability, and is less likely to cause fogging.

(Image forming device)
Next, the image forming apparatus of the present invention will be described. The image forming apparatus of the present invention is equipped with the electrophotographic photosensitive member of the present invention.

  FIG. 6 is a schematic diagram showing a basic configuration of a preferred embodiment of the image forming apparatus of the present invention. The image forming apparatus 100 shown in FIG. 6 exposes the electrophotographic photosensitive member 1, the charging device 8 that charges the electrophotographic photosensitive member 1, the power source 9 connected to the charging device 8, and the charged electrophotographic photosensitive member 1. An exposure device 10 for forming an electrostatic latent image, a developing device 11 for developing the electrostatic latent image to form a toner image, and a toner image developed on the electrophotographic photosensitive member 7 by the developing device 11 being transferred. A transfer device 12 for transferring to a medium, a cleaning device 13, a static eliminator 14, and a fixing device 15 are provided.

  In the image forming apparatus 100, the exposure device 10, the developing device 11, the transfer device 12, the cleaning device 13, and the static eliminator 14 are arranged in this order along the circumferential direction of the electrophotographic photoreceptor 1.

  In addition, since the electrophotographic photoreceptor 1 of the present invention has excellent wear resistance, it can be preferably used in the image forming apparatus 100 that employs the contact charging type charging device 8 in which an AC voltage is superimposed on a DC voltage. . Further, the charging device 8 may be a charging device that is charged by a corona discharge method.

  Further, as the light source of the exposure apparatus 10, a light source in the ultraviolet range, specifically, 380 to 500 nm may be used as the exposure wavelength.

The image forming apparatus 100 is particularly good in terms of image quality when using spherical toner, more specifically, spherical toner having an average shape index (ML ² / A) of 100 to 150. In such a spherical toner, toner slip usually occurs at the contact portion between the cleaning blade and the photosensitive member, and the cleaning property tends to deteriorate, but the electrophotographic photosensitive member of the present invention has an appropriate hardness, Good cleaning properties can be realized without causing toner slip.

  The average particle size of the toner is preferably 2 to 12 μm, and more preferably 3 to 9 μm. When the average particle size is less than 2 μm, cleaning tends to be difficult, aggregation tends to occur, and image quality is liable to occur. On the other hand, if it exceeds 12 μm, the resolution tends to be lowered.

  The spherical toner will be described in detail. For example, the production method includes particles obtained by a kneading pulverization method in which a binder resin, a colorant, a release agent, and a charge control agent as necessary are kneaded, pulverized, and classified. A method of changing the shape by mechanical impact force or thermal energy, a dispersion formed by emulsion polymerization of a polymerizable monomer of a binder resin, a colorant, a release agent, and a charge control agent if necessary The emulsion polymerization aggregation method to obtain toner particles by mixing, agglomerating and heating and melting, a polymerizable monomer and a colorant, a release agent, and a charge control agent as required A suspension polymerization method in which a solution such as a suspension is polymerized by suspending in an aqueous solvent, a binder resin and a colorant, a release agent, and if necessary, a solution such as a charge control agent is suspended in an aqueous solvent and granulated. A dissolution suspension method or the like can be used.

  Further, 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 heated and fused to have a core-shell structure can be used. Among these, from the viewpoint of shape and particle size distribution control, the suspension polymerization method, the emulsion polymerization aggregation method and the dissolution suspension method which are produced with an aqueous solvent are preferable, and the emulsion polymerization aggregation method is particularly preferable. The toner base is composed of a binder resin, a colorant, and a release agent. If necessary, silica or a charge control agent may be used as a dispersion aid.

  Binder resins used in the toner include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate. , Α-methylene aliphatic monocarboxylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, dodecyl methacrylate, ethyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, Homopolymers and copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone and the like.

  Typical examples include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-maleic anhydride copolymer. , Polyethylene, polypropylene and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, chrome yellow, ultramarine blue, deyupon oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and 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 and the like are specific examples.

  Specific examples of the release agent include low-molecular polyethylene, low-molecular polypropylene, Fischer-Tropish wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Examples of the antistatic agent include azo metal complex compounds, metal complex compounds of salicylic acid, and resin-type compounds containing a polar group.

  The toner used in this embodiment may use additives other than those described above. For example, lubricant particles and abrasive particles. Examples of the lubricant particles include graphite, molybdenum disulfide, talc, low molecular weight polyolefin, aliphatic amides, silicones, various vegetable waxes, and the like. Examples of the abrasive include inorganic particles such as cerium oxide, magnesium titanate, and silicon nitride, and organic fine particles such as styrene resin fine particles and styrene acrylic resin fine particles.

  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 can be set as appropriate.

  FIG. 7 is a schematic diagram showing a basic configuration of another preferred embodiment of the image forming apparatus of the present invention. The image forming apparatus 200 is an intermediate transfer type image forming apparatus. In the housing 220, four electrophotographic photosensitive members 201a to 201d (for example, 201a is yellow, 201b is magenta, 201c is cyan, and 201d is black). Are formed in parallel with each other along the intermediate transfer belt 209. Here, the electrophotographic photoreceptors 201a to 201d mounted on the image forming apparatus 200 are the electrophotographic photoreceptors of the present invention.

  Each of the electrophotographic photoreceptors 201a to 201d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 202a to 202d, the developing devices 204a to 204d, and the primary transfer roll 210a along the rotation direction. To 210d and cleaning blades 215a to 215d are arranged. Each of the developing devices 204a to 204d can be supplied with toner of four colors, yellow, magenta, cyan, and black, stored in the toner cartridges 205a to 205d. Further, the primary transfer rolls 210a to 210d are in contact with the electrophotographic photosensitive members 201a to 201d via the intermediate transfer belt 209, respectively.

  Further, a laser light source (exposure device) 203 is disposed at a predetermined position in the housing 220. Laser light emitted from the laser light source 203 can be applied to the surfaces of the electrophotographic photosensitive members 201a to 201d after charging. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 201a to 201d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 209 in an overlapping manner.

  The intermediate transfer belt 209 is supported with a predetermined tension by a drive roll 206, a backup roll 208, and a tension roll 207, and can rotate without causing deflection due to the rotation of these rolls. The secondary transfer roll 213 is disposed so as to contact the backup roll 208 via the intermediate transfer belt 209. The intermediate transfer belt 209 that has passed between the backup roll 208 and the secondary transfer roll 213 is cleaned by a cleaning blade 216 disposed in the vicinity of the drive roll 206, for example, and then repeatedly used for the next image forming process. Is done.

  Further, a tray (transfer medium tray) 211 is provided at a predetermined position in the housing 220, and the transfer medium 230 such as paper in the tray 211 is transferred by the transfer roll 212 to the intermediate transfer belt 209 and the secondary transfer roll. Then, the sheet is sequentially transferred between the two fixing rolls 214 that are in contact with each other and between the two fixing rolls 214 and then discharged to the outside of the housing 220.

  In the above description, the case where the intermediate transfer belt 209 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 209 or a drum shape. Also good. When a belt-shaped configuration such as the intermediate transfer belt 209 is adopted as the intermediate transfer member, generally the thickness of the belt is preferably 50 to 500 μm, more preferably 60 to 150 μm. Note that the thickness of the belt can be appropriately selected according to the hardness of the material. When a drum-shaped configuration is adopted as the intermediate transfer member, it is preferable to use a cylindrical substrate formed of aluminum, stainless steel (SUS), copper, or the like as the substrate. If necessary, an elastic layer can be coated on the cylindrical substrate, and a surface layer can be formed on the elastic layer.

  The medium to be transferred in the present invention is not particularly limited as long as it is a medium for transferring a toner image formed in the shape of an electrophotographic photosensitive member. For example, when transferring directly from an electrophotographic photosensitive member to paper or the like, paper or the like is a transfer medium, and when an intermediate transfer member is used, the intermediate transfer member is a transfer medium.

(Process cartridge)
Next, a process cartridge equipped with the electrophotographic photosensitive member of the present invention will be described. FIG. 8 is a schematic diagram showing a basic configuration of a preferred embodiment of the process cartridge of the present invention.

  In the process cartridge 300, a charging device 8, an exposure device 10, a developing device 11, a cleaning device 13, and a static eliminator 14 are combined in the case 20 together with the electrophotographic photosensitive member 1 using a mounting rail 16. . The case 20 may be provided with an opening 10 for exposure instead of the exposure apparatus 10. The process cartridge 300 is detachable from the image forming apparatus main body including the transfer device 12, the fixing device 15, and other components not shown, and constitutes the image forming apparatus together with the image forming apparatus main body. To do.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following examples, “part” means part by mass.

Example 1
An aluminum pipe having a diameter of 84 mmφ × 347 mm and a wall thickness of 1 mm is roughened by subjecting it to a liquid honing treatment using an abrasive (made by Showa Titanium Co., Ltd., trade name: alumina beads CB-A30S, average particle diameter D50 = 30 μm), and the center line What was roughened so that average roughness Ra might be set to 0.18 micrometer was prepared as an electroconductive support body.

  Next, 6 parts of polyvinyl butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.), 12 parts of blocked isocyanate (Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, zinc oxide (Nano Tech ZnO, manufactured by Sea Chemical Industries) Batch type milling material consisting of 41 parts of primary particle size 30 nm, 1 part of silicone ball (Tospearl 120, manufactured by Toshiba Silicone), 100 ppm of silicone oil (SH29PA, manufactured by Toray Dow Corning Silicone) as leveling agent and 52 parts of methyl ethyl ketone The coating solution for undercoat layer formation was prepared by dispersing for 10 hours. The obtained coating solution for forming the undercoat layer was dip-coated on a conductive support and dried by heating at 150 ° C. for 30 minutes to form an undercoat layer having a thickness of 20.0 μm.

  Next, a solution in which 1 part of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar) was dissolved in 100 parts of n-butyl acetate and a Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-rays 1 part of hydroxygallium phthalocyanine having diffraction peaks at 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 °, and 28.3 °, The mixture was dispersed in a sand mill for 5 hours together with 150 parts of glass beads having an outer diameter of 1 mm to prepare a charge generation layer forming coating solution. The obtained coating solution was dip-coated on the undercoat layer and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.20 μm.

  Next, as a binder resin for the charge transport layer, structural units represented by the following formulas (Ia), (II-a) and (IV-a) are used in a molar ratio of 40:10:50. A copolymer having the same was synthesized. The copolymer had a weight average molecular weight of 60000 and was a random copolymer. 6 parts of the binder resin, 4 parts of N, N′-diphenyl-N, N′-bis (3-methyl)-[1,1′biphenyl] -4,4′-diamine as the charge transport material, 80 parts of tetrahydrofuran And 0.2 part of 2,6-di-t-butyl-4-methylphenol were mixed to prepare a coating solution for forming a charge transport layer. The obtained coating solution was applied onto the charge generation layer by a dip coating apparatus and dried by heating at 120 ° C. for 40 minutes. Then, a charge transport layer having a thickness of 25 μm was formed, and the electrophotographic photosensitive member of Example 1 was obtained.

  The obtained electrophotographic photosensitive member was mounted on a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. 6 to produce an image forming apparatus of Example 1. In the above full color laser printer, a roller charger (BCR) as a charging device, ROS using a 780 nm semiconductor laser as an exposure device, a two-component reversal development method as a development method, and a roller charger (as a transfer device) BTR), the belt intermediate transfer system was adopted as the transfer system.

(Example 2)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, structural units represented by the above formulas (Ia), (II-a) and (IV-a) A copolymer having a molar ratio of 70:10:30 was synthesized. The copolymer had a weight average molecular weight of 45000 and was a random copolymer. A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin, whereby an electrophotographic photoreceptor of Example 2 was obtained. Further, an image forming apparatus of Example 2 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

Example 3
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, structural units represented by the above formulas (Ia), (II-a) and (IV-a) A copolymer having a molar ratio of 20:20:60 was synthesized. This copolymer had a weight average molecular weight of 65,000 and was a random copolymer. A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin, whereby an electrophotographic photoreceptor of Example 3 was obtained. Further, an image forming apparatus of Example 3 was produced in the same manner as in Example 1 except that the obtained electrophotographic photosensitive member was used.

Example 4
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, structural units represented by the above formulas (Ib), (II-b) and (IV-b) A copolymer having a molar ratio of 40:20:40 was synthesized. The copolymer had a weight average molecular weight of 55000 and was a random copolymer. A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin, whereby an electrophotographic photoreceptor of Example 4 was obtained. Further, an image forming apparatus of Example 4 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Example 5)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, structural units represented by the above formulas (Ic), (II-c) and (IV-c) A copolymer having a molar ratio of 40:20:40 was synthesized. The copolymer had a weight average molecular weight of 55000 and was a random copolymer. A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin, whereby an electrophotographic photoreceptor of Example 5 was obtained. Further, an image forming apparatus of Example 5 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Example 6)
In the same manner as in Example 1, an undercoat layer was formed on the conductive support. Next, 1 part of chlorogallium phthalocyanine having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.5 °, and 28.3 ° in the X-ray diffraction spectrum is added. A polybutyral resin (manufactured by Sekisui Chemical Co., Ltd., BM-S) and 100 parts of butyl acetate were mixed and dispersed with a glass bead for 1 hour in a paint shaker to prepare a coating solution for forming a charge generation layer. The obtained coating solution was dip-coated on the undercoat layer and dried at 100 ° C. for 10 minutes to form a charge generation layer.

  A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 to obtain an electrophotographic photoreceptor of Example 6. Further, an image forming apparatus of Example 6 was produced in the same manner as in Example 1 except that the obtained electrophotographic photosensitive member was used.

(Example 7)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, in the formation of the charge transport layer, the charge transport material is N, N′-diphenyl-N, N′-bis (3-methyl)-[1,1′biphenyl] -4,4′-diamine. A charge transport layer was formed in the same manner as in Example 1 except that 4 parts was changed to 3 parts of the compound represented by the following formula (X-1) to obtain an electrophotographic photoreceptor of Example 7. Further, an image forming apparatus of Example 7 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Example 8)
A conductive support was prepared in the same manner as in Example 1. Next, 10 parts of tin dioxide-coated barium sulfate, 2 parts of titanium oxide, 6 parts of phenol resin, 0.001 part of silicone oil are dispersed in a mixed solvent of 4 parts of methanol and 16 parts of methoxypropanol, and the first subbing layer A forming coating solution was prepared. The obtained coating solution was dip-coated on a conductive support and cured at 140 ° C. for 30 minutes to form a first undercoat layer having a thickness of 15 μm. Next, on the first undercoat layer, a second undercoat layer was formed by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol. The coating solution was dip coated and dried to provide a second undercoat layer having a thickness of 0.5 μm. Next, a charge generation layer and a charge transport layer were formed in the same manner as in Example 1 to obtain an electrophotographic photoreceptor of Example 8. Further, an image forming apparatus of Example 8 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Comparative Example 1)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, a charge transport layer was formed in the same manner as in Example 1 except that bisphenol A type polycarbonate (manufactured by Teijin, Panlite) was used as the binder resin. An electrophotographic photosensitive member was obtained. Further, an image forming apparatus of Comparative Example 1 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Comparative Example 2)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, a charge transport layer was formed in the same manner as in Example 1 except that bisphenol A type polyarylate (manufactured by Unitika, U polymer) was used as a binder resin. 2 electrophotographic photoreceptor was obtained. Further, an image forming apparatus of Comparative Example 2 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

(Heat resistance, abrasion resistance and image quality evaluation test)
For the electrophotographic photoreceptors of Examples 1 to 8 and Comparative Examples 1 to 2, the deflection temperature under load of the charge transport layer was evaluated with a load of 1.82 MPa in accordance with the method shown in JIS K-7207. Further, using the image forming apparatuses of Examples 1 to 8 and Comparative Examples 1 and 2, the photoreceptor wear rate after printing 10,000 sheets (the value obtained by dividing the film thickness difference before and after printing by the number of photoreceptor rotation cycles). Evaluation was made using a self-made eddy current film thickness meter. Furthermore, the print image quality after printing 10,000 sheets was visually evaluated. The results obtained are shown in Table 6.

  As shown in Table 6, it was confirmed that the electrophotographic photoreceptors of Examples 1 to 8 had high heat resistance and suppressed wear. In addition, the image forming apparatuses of Examples 1 to 8 obtained good image quality even after long-term printing.

  On the other hand, it was confirmed that the electrophotographic photoreceptors of Comparative Examples 1 and 2 had low heat resistance and significant wear. In addition, the image forming apparatuses of Comparative Examples 1 and 2 had streak defects that seemed to be caused by thermal deterioration and wear after long-term printing.

Example 9
In the same manner as in Example 1, an undercoat layer, a charge generation layer, and a charge transport layer were formed on a conductive support. Next, 2 parts of the compound represented by the following formula (X-2), 2 parts of methyltrimethoxysilane, 0.5 part of tetramethoxysilane and 0.3 part of colloidal silica are mixed with 5 parts of isopropyl alcohol, 3 parts of tetrahydrofuran and 0 parts of distilled water. It was dissolved in 3 parts of a mixed solvent, 0.5 parts of ion exchange resin (Amberlyst 15E: manufactured by Rohm and Haas) was added, and the mixture was stirred at room temperature for 24 hours for hydrolysis.

The ion exchange resin was separated by filtration from the hydrolyzed product, and 0.1 parts of aluminum trisacetylacetonate (Al (aqaq) ₃ ) and 3,5-di-t-butyl-4-hydroxy were obtained from the obtained filtrate. 0.4 part of toluene (BHT) and 0.02 part of polytetrafluoroethylene particles (Daikin Industries, Lubron L-2) were added to prepare a coating solution for forming a protective layer. This coating solution was applied on the charge transport layer by a ring-type dip coating method and dried at room temperature for 30 minutes. Thereafter, the film was cured by heat treatment at 170 ° C. for 1 hour to form a protective layer having a film thickness of about 3 μm. The electrophotographic photoreceptor was visually evaluated for the presence or absence of cracks on the surface of the charge transport layer. Further, the obtained electrophotographic photosensitive member is mounted on a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. 6 to produce the image forming apparatus of Example 9, and print 10,000 sheets. The subsequent print image quality was evaluated visually. The results obtained are shown in Table 7.

(Example 10)
In the same manner as in Example 1, an undercoat layer, a charge generation layer, and a charge transport layer were formed on a conductive support. Next, 2 parts of each of the compounds represented by the following formulas (X-3) and (X-4), 0.05 part of tetramethoxysilane, 5 parts of isopropyl alcohol, 3 parts of tetrahydrofuran and 0. This was dissolved in 3 parts of a mixed solvent, 0.05 parts of an ion exchange resin (Amberlyst 15E: manufactured by Rohm and Haas) was added thereto, and the mixture was stirred at room temperature for hydrolysis for 24 hours.

  The ion exchange resin was filtered and separated from the liquid thus obtained, and 0.04 part of aluminum trisacetylacetonate and 0.02 part of 3,5-di-tert-butyl-4-hydroxytoluene were added to 2 parts of the obtained filtrate. A coating solution for forming a protective layer was prepared. This coating solution was applied to the charge transport layer by a ring type dip coating method and dried at room temperature for 30 minutes. Thereafter, the film was cured by heat treatment at 170 ° C. for 1 hour to form a protective layer having a thickness of about 3 μm. Thus, an electrophotographic photoreceptor of Example 10 was obtained. The electrophotographic photoreceptor was visually evaluated for the presence or absence of cracks on the surface of the charge transport layer. Further, the obtained electrophotographic photosensitive member is mounted on a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. 6 to produce the image forming apparatus of Example 10 and print 10,000 sheets. The subsequent print image quality was evaluated visually. The results obtained are shown in Table 7.

(Comparative Example 3)
Except for using bisphenol A-type polycarbonate (manufactured by Teijin, Panlite) as the polymer compound for the charge transport layer, an undercoat layer, a charge shipping layer, a charge transport layer are formed on the conductive support in the same manner as in Example 9. And the protective layer was formed and the electrophotographic photoreceptor of the comparative example 3 was obtained. The electrophotographic photosensitive member was visually evaluated for the presence or absence of cracks on the surface of the charge transport layer. Further, the obtained electrophotographic photosensitive member is mounted on a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. The subsequent print image quality was evaluated visually. The results obtained are shown in Table 7.

(Comparative Example 4)
Except for using bisphenol A-type polycarbonate (manufactured by Teijin, Panlite) as the polymer compound for the charge transport layer, an undercoat layer, a charge shipping layer, a charge transport layer are formed on the conductive support in the same manner as in Example 10. And the protective layer was formed and the electrophotographic photoreceptor of the comparative example 4 was obtained. The electrophotographic photoreceptor was visually evaluated for the presence or absence of cracks on the surface of the charge transport layer. Further, the obtained electrophotographic photoreceptor is mounted on a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) having the configuration shown in FIG. The subsequent print image quality was evaluated visually. The results obtained are shown in Table 7.

  As is clear from the results shown in Table 10, the electrophotographic photoreceptors of Examples 9 and 10 did not generate cracks on the surface of the charge transport layer even when a protective layer was provided, and an image forming apparatus using the same The image quality was good after long-term printing.

  On the other hand, in the electrophotographic photoreceptors of Comparative Examples 3 and 4, it was confirmed that cracks were generated on the surface of the charge transport layer due to mechanical deterioration due to thermal deterioration or shrinkage by providing a protective layer. Also, due to this crack, the image forming apparatus has image quality defects after long-term printing.

(Example 11)
In the same manner as in Example 1, an undercoat layer was formed on the conductive support. Next, when the charge generation layer is formed, the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum is 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18. On the undercoat layer in the same manner as in Example 1 except that 1 part of t-selenium was used instead of 1 part of hydroxygallium phthalocyanine having strong diffraction peaks at 6 °, 25.1 ° and 28.3 °. A charge generation layer was formed. Further, a charge transport layer was formed on the charge generation layer in the same manner as in Example 1 to obtain the electrophotographic photoreceptor of Example 11.

  The obtained electrophotographic photosensitive member was mounted on a remodeling machine in which the exposure light source of a full-color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) was replaced with a gallium nitride laser having a wavelength of 420 nm, and the image forming apparatus of Example 11 was mounted. Produced. However, 10,000 sheets were printed using the image forming apparatus, and the print image quality after 10,000 sheets printing was visually evaluated. Table 8 shows the obtained results.

(Comparative Example 5)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when the charge transport layer is formed, the charge transport layer is formed in the same manner as in Example 1 except that bisphenol A type polycarbonate (manufactured by Teijin, Panlite) is used as the binder resin of the charge transport layer. An electrophotographic photoreceptor of Comparative Example 5 was obtained. An image forming apparatus was produced in the same manner as in Example 11 except that the obtained electrophotographic photosensitive member was used. Except for using such an image forming apparatus, 10,000 sheets were printed in the same manner as in Example 11, and the print image quality after 10,000 sheets was visually evaluated. Table 8 shows the obtained results.

  As is apparent from the results shown in Table 8, the electrophotographic photosensitive member of Example 11 has high heat resistance, high mechanical strength, and good image quality was obtained even in an image forming apparatus using a short wavelength laser. . On the other hand, in the electrophotographic photosensitive member of Comparative Example 5, the polymer material of the charge transport layer was thermally and mechanically deteriorated by short wavelength laser irradiation, and as a result, fogging occurred in the image forming apparatus.

(Example 12)
In the same manner as in Example 1, an undercoat layer, a charge generation layer and a charge transport layer were formed on a conductive support to obtain an electrophotographic photoreceptor of Example 12. On the other hand, 100 parts of a polyester resin containing terephthalic acid, 2,2-bis (4-hydroxyethoxyphenyl) propane and cyclohexanedimethanol in a molar ratio of 10: 7: 3, 4 parts of carbon black, and carnauba Base particles having an average shape factor (ML ² / A) of 141 consisting of 5 parts of wax were prepared. Next, using the mother particles, a black toner, a cyan toner in which carbon black is changed to CI pigment blue 15: 3, a magenta toner in which carbon black is changed to R122, and a yellow toner in which carbon black is changed to Y180 are prepared. did.

  The obtained toner and the electrophotographic photosensitive member of Example 12 were mounted on a full color laser printer (DocuPrint C620, manufactured by Fuji Xerox Co., Ltd.) to produce an image forming apparatus of Example 12. The obtained image forming apparatus was used to print 10,000 sheets, and the image quality after printing 10,000 sheets was visually evaluated. Table 9 shows the obtained results.

(Comparative Example 6)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when the charge transport layer was formed, a charge transport layer was formed in the same manner as in Example 1 except that bisphenol A type polycarbonate (manufactured by Teijin, Panlite) was used as a binder resin. An electrophotographic photosensitive member was obtained. An image forming apparatus of Comparative Example 6 was produced in the same manner as in Example 12 except that the obtained electrophotographic photosensitive member was used. Except for using such an image forming apparatus, 10,000 sheets were printed in the same manner as in Example 12, and the print image quality after 10,000 sheets was visually evaluated. Table 9 shows the obtained results.

  As is apparent from the results shown in Table 9, the electrophotographic photosensitive member of Example 12 has high mechanical strength, and even when spherical toner is used, high cleaning properties can be secured, and the image forming apparatus is good even after long-term printing. A good image quality was obtained. On the other hand, since the electrophotographic photosensitive member of Comparative Example 6 has low mechanical strength, the spherical toner was purged and degenerated, and as a result, the image forming apparatus was striped after long-term printing.

(Comparative Example 7)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, the structural unit represented by the above formula (Ia) and the structural unit represented by (II-a) A copolymer having a structural unit having a phenylene group bonded at the p-position and a structural unit represented by (IV-a) in a molar ratio of 70:10:20 was synthesized. Incidentally, such a copolymer has a weight average molecular weight of 4500 0 was a random copolymer. An attempt was made to prepare a coating solution for forming a charge transport layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin. However, since the phenylene group has a structural unit bonded at the p-position, the copolymer is not dissolved in the coating solution, and the coating solution cannot be prepared. For this reason, an electrophotographic photoreceptor cannot be produced.

(Comparative Example 8)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, the structural units represented by the above formulas (Ia) and (IV-a) in a molar ratio of 70: A copolymer having a ratio of 30 was synthesized. The copolymer had a weight average molecular weight of 45000 and was a random copolymer. An attempt was made to prepare a coating solution for forming a charge transport layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin. However, since the structural unit having high flexibility is not included in the copolymer, the copolymer is not dissolved in the coating solution, and the coating solution cannot be prepared. For this reason, an electrophotographic photoreceptor cannot be produced.

(Comparative Example 9)
In the same manner as in Example 1, an undercoat layer and a charge generation layer were formed on a conductive support. Next, when forming the charge transport layer, first, as the binder resin for the charge transport layer, the structural units represented by the above formulas (II-a) and (IV-a) in a molar ratio of 70: A copolymer having a ratio of 30 was synthesized. The copolymer had a weight average molecular weight of 45000 and was a random copolymer. A charge transport layer was formed on the charge generation layer in the same manner as in Example 1 except that such a copolymer was used as a binder resin, whereby an electrophotographic photoreceptor of Comparative Example 9 was obtained. Further, an image forming apparatus of Comparative Example 9 was produced in the same manner as Example 1 except that the obtained electrophotographic photosensitive member was used.

  For the electrophotographic photosensitive member of Comparative Example 9, the deflection temperature under load of the charge transport layer was evaluated according to the method described in JIS K-7207 with a load of 1.82 MPa. Also, using the image forming apparatus of Comparative Example 9, a self-made eddy current film thickness meter was used to calculate the photoconductor wear rate after 10,000 prints (the value obtained by dividing the film thickness difference before and after printing by the number of photoconductor rotation cycles). Evaluated. As a result, in the electrophotographic photosensitive member of Comparative Example 9, the copolymer, which is the binder resin of the charge transport layer, does not contain a structural unit corresponding to the general formula (I), so that the heat resistance is low. In addition, it was confirmed that the abrasion resistance was insufficient and the film could not withstand image formation.

  As described above, it was confirmed that the electrophotographic photosensitive member of the present invention has high heat resistance and high mechanical strength. Further, it was confirmed that the image forming apparatus using the electrophotographic photosensitive member of the present invention can obtain good image quality even after long-term printing.

  Furthermore, in the electrophotographic photosensitive member of the present invention, the copolymer according to the present invention has high heat resistance and high mechanical strength. Therefore, when such a copolymer is contained in the charge transporting layer, the charge transporting is performed. Even when a protective layer was provided on the layer, it was confirmed that no cracks occurred on the surface of the charge transport layer. Further, in the image forming apparatus provided with the electrophotographic photosensitive member of the present invention, even when a short wavelength laser of 450 nm or less is used as an exposure light source, no deterioration occurs, and the average shape factor (ML2 / A) is 100 to 150. Even when spherical toner is used, high cleaning performance can be realized, and in either case, good image quality is obtained after long-term printing.

1 is a schematic cross-sectional view showing a preferred embodiment of an electrophotographic photoreceptor of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. FIG. 6 is a schematic cross-sectional view showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. 1 is a schematic diagram illustrating a basic configuration of a preferred embodiment of an image forming apparatus of the present invention. It is a schematic diagram which shows the basic composition of other suitable embodiment of the image forming apparatus of this invention. It is a schematic diagram showing a basic configuration of a preferred embodiment of the process cartridge of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photoreceptor, 2 ... Conductive support body, 3 ... Photosensitive layer.

Claims (7)

Comprising a conductive support and a photosensitive layer formed on the conductive support;
The photosensitive layer is a copolymer having a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II) or (III), or represented by the following general formula (I). An electrophotographic photoreceptor comprising a mixture of a homopolymer having a structural unit and a homopolymer having a structural unit represented by the following general formula (II) or (III).

[In the above formula, A ¹ and A ² each independently represent a divalent substituent, R ¹ , R ² , R ⁵ and R ⁶ each independently represent an alkylene group, and R ³ , R ⁴ and R ⁷ Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituent containing a silicon atom or a substituent containing a fluorine atom, and a, b and c each represents an integer of 0 to 4. However, when c is an integer of 2 or more, these substituents may be bonded to each other to form a ring. ] The said copolymer has a structural unit represented by the following general formula (II-1), or a structural unit represented by the following general formula (III-1), It is characterized by the above-mentioned. Electrophotographic photoreceptor.

[In the above formula, A ¹ and A ² each independently represent a divalent substituent, R ¹ , R ² , R ⁵ and R ⁶ each independently represent an alkylene group, and R ³ , R ⁴ and R ⁷ Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituent containing a silicon atom or a substituent containing a fluorine atom, and a, b and c each represents an integer of 0 to 4. However, when c is an integer of 2 or more, these substituents may be bonded to each other to form a ring. ]   The electrophotographic photosensitive member according to claim 1, wherein the copolymer is a random copolymer. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the copolymer further has a structural unit represented by the following general formula (IV).

[In the above formula, X and Y each independently represent a divalent substituent. ]   A copolymer having the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) or (III), or the structural unit represented by the general formula (I); In a mixture of a homopolymer having a homopolymer having a structural unit represented by the general formula (II) or (III), the structural unit represented by the general formula (I) and the general formula (II) Or the molar ratio with the structural unit represented by (III) is 1: 9-9: 1, The electrophotographic photosensitive member as described in any one of Claims 1-4 characterized by the above-mentioned. The electrophotographic photosensitive member according to any one of claims 1 to 5,
A charging device for charging the electrophotographic photoreceptor;
An exposure apparatus that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image;
A developing device for developing the electrostatic latent image to form a toner image;
A transfer device for transferring the toner image to a transfer medium;
An image forming apparatus comprising: The electrophotographic photosensitive member according to any one of claims 1 to 5,
A charging device for charging the electrophotographic photosensitive member, an exposure device for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, a developing device for developing the electrostatic latent image to form a toner image, and At least one selected from cleaning devices for cleaning the electrophotographic photosensitive member;
A process cartridge comprising:

Images