JP3871285B2 - Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member used for a copying machine, a printer, and the like, a process cartridge and an electrophotographic apparatus using the electrophotographic photosensitive member. In particular, the present invention relates to an electrophotographic photoreceptor containing at least a specific binder resin in a surface layer, a process cartridge and an electrophotographic apparatus using the electrophotographic photoreceptor.
[0002]
[Prior art]
Inorganic materials such as zinc oxide, selenium, and cadmium sulfide have been known as photoconductive materials for electrophotographic photoreceptors mounted on printers and copiers. Recently, however, organic polyvinyl carbazole, phthalocyanine, azo pigments and the like have been attracting attention for advantages such as high productivity and no pollution, and those obtained by improving them have been widely used.
[0003]
Image formation in an electrophotographic apparatus is generally performed as follows. First, the photosensitive drum is charged by a charging device. Then, an image is exposed to the charged area to form an electrostatic latent image. Next, the electrostatic latent image is developed with a developer to form a visible image. This visible image is transferred to a recording material such as paper and fixed by heat or pressure. The photosensitive drum is charged again after cleaning, and the above steps are repeated.
[0004]
In this way, the surface of the photosensitive drum is exposed to electrical and mechanical treatments in various processes in the electrophotographic process, so that the surface layer has a strong durability against these processes for repeated use of the photosensitive drum. It is necessary to have
[0005]
The photosensitive drum is generally formed by providing a film of an electrophotographic photosensitive member around a conductive cylindrical support. This electrophotographic photosensitive member has a multilayer structure of a conductive layer, an undercoat layer and a photosensitive layer. Among these layers, the photosensitive layer is an essential component. The photosensitive layer has a single layer structure or a two-layer structure including a charge generation layer and a charge transport layer. In the case of a two-layer structure, the charge generation layer contains a charge generation material and the charge transport layer contains a charge transport material. As the photosensitive layer, a function-separated type two-layered photosensitive layer is often used for various reasons such as durability, potential stability, sensitivity, responsiveness, and material selection tolerance of the photosensitive layer.
[0006]
Since this charge generation / transport material alone does not have film-forming properties, it is generally formed with a binder resin. Therefore, it is no exaggeration to say that the surface properties of the photoreceptor are determined by the selection of these resins.
[0007]
On the other hand, as a primary charging device for primarily charging a photosensitive drum, recently, from the viewpoint of energy saving / ecology, a method in which a charging member is brought into direct contact with a photosensitive member and the photosensitive drum is charged by discharge has been increasing. In this method, since the electrical load on the photosensitive layer is large, the abrasion of the surface layer is large, and in addition to the application of an AC voltage during charging, the DC voltage is superimposed particularly for charging stability, Abrasion of surface layer due to load is large.
[0008]
Therefore, in the electrophotographic process related to the surface characteristics of the photosensitive drum, the electrical load due to electrification is increasing in addition to the mechanical load due to cleaning, which has been a problem in the past, and satisfies the repeated durability characteristics. Therefore, it is necessary to give the surface layer strength to these.
[0009]
However, a binder resin that satisfies both the electrical load resistance and the mechanical strength without impairing the photoconductive properties and other properties has not yet been obtained.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide an electrophotographic photosensitive member having high mechanical strength and electrical load resistance, a process cartridge and an electrophotographic apparatus using the electrophotographic photosensitive member.
[0011]
[Means for Solving the Problems]
The present inventor has completed the present invention as a result of various studies in order to solve the above problems. In the present invention, a resin having a bisphenol-type polycarbonate skeleton is used to give mechanical strength, and at least silicon as shown in the following structure is used so that bonds in the polycarbonate are not broken and decomposed by external energy. A silicon-containing polycarbonate having a repeating unit that binds a phenylene group through it is used as a binder resin for at least the surface layer.
[0012]
That is, the present invention provides a charging means for charging the electrophotographic photosensitive member by contacting the electrophotographic photosensitive member and applying a DC voltage superimposed on an AC voltage, and an image on the charged electrophotographic photosensitive member. In an electrophotographic apparatus comprising: an image exposing unit that performs exposure to form an electrostatic latent image; and a developing unit that develops the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner.
Repeating unit said electrophotographic photosensitive member is, on a conductive support and have a photosensitive layer, at least the surface layer, and a repeating unit represented by the following formula (1), represented by the following formula (2) When an electrophotographic apparatus, wherein an electrophotographic photoreceptor containing a polycarbonate copolymer having:
[0013]
[Formula 4]
(In the above formula (1), R ₁ To R ₈ Represents a hydrocarbon group of a hydrogen atom, a halogen atom or a carbon number 1 to 17, R ₉ To R ₁₈ represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 17 carbon atoms);
[0014]
Embedded image
(In the above formula (2), R ₁₉ to R ₂₆ represents a hydrocarbon group of a hydrogen atom, a halogen atom or a carbon number 1 to 17, X is [0015]
Embedded image
The stands, R ₂₉ to R ₃₈ are a hydrogen atom, a halogen atom or carbon atoms represent 1-17 hydrocarbon group).
[0017]
Conventionally, bisphenol-type polycarbonate has been widely used as a binder resin for the surface layer. However, when contact charging is widespread and the method of superimposing a DC voltage on an AC voltage is used to stably charge the photosensitive drum, the surface of the photosensitive drum is subjected to a strong electrical load and only AC is applied. Compared with the case, the wear is remarkably increased. Therefore, a method such as increasing the strength of the resin itself in order to increase the strength of the electrical load resistance as a film, increasing the film strength by increasing the affinity with the charge transport material (and / or the charge generation material), etc. Can be considered.
[0018]
In the present invention, the resin is designed with the aim of increasing the strength of the former binder resin, and it is estimated that the central skeleton is difficult to decompose even if the resin is exposed to a high energy state by replacing the carbon of the central skeleton of bisphenol with silicon. It was configured.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the conductive support used in the electrophotographic photosensitive member of the present invention include metals such as aluminum, copper, nickel and silver or alloys thereof, and conductive metal oxides such as antimony oxide, indium oxide and tin oxide. , Carbon fiber, carbon black, and those obtained by mixing and molding graphite powder and resin.
[0020]
Furthermore, it is also possible to form a conductive layer on the support in order to cover defects on the support and to protect the support. For example, metal powder such as aluminum, copper, nickel, silver, conductive metal oxide such as antimony oxide, indium oxide, tin oxide, polymer conductive material such as polyvinyl, polyaniline, polymer electrolyte material, carbon fiber, Conductive materials such as carbon black, graphite powder or conductive powder whose surface is coated with such conductive materials such as thermoplastic resins such as acrylic resin, polyester, polyamide, polyvinyl acetate, polycarbonate, polyvinyl butyral, polyurethane, phenol Examples thereof include a resin, a thermosetting resin such as an epoxy resin, a resin dispersed in a binder resin such as a photocurable resin, and a resin coated with an additive as necessary.
[0021]
As an example of the surface layer of the electrophotographic photosensitive member of the present invention, a single layer structure may be applied to the entire photosensitive layer. As a particularly effective example, a charge transport layer is laminated on the charge generation layer. An example of application to the charge transport layer of a layered photoreceptor separated in function is given. Further, in the case of a photoreceptor having a protective layer on the photosensitive layer, an example of application to the protective layer is possible.
[0022]
Specific examples of laminated photoreceptors include charge generation materials such as azo pigments such as Sudan Red and Diane Blue, quinone pigments such as anthanthrone, perylene pigments, indigo pigments, copper phthalocyanine, and titanyl phthalocyanine. Examples include phthalocyanine pigments, thermoplastic resins such as acrylic resins, polyester resins, polyamide resins, polyvinyl acetate resins, polycarbonate resins, polyvinyl butyral resins, and polyvinyl benzal resins, thermosetting resins such as polyurethane resins, phenol resins, and epoxy resins. A charge generation layer can be formed by dispersing a resin or the like in a binder resin together with a suitable solvent and coating the dispersion on a conductive support. The film thickness of such a charge generation layer is preferably 5 μm or less, more preferably 0.05 to 2 μm.
[0023]
The charge transport layer is a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene and phenanthrene in the main chain or side chain, a nitrogen-containing cyclic compound such as indole, carbazole, oxadiazole and pyrazoline, a hydrazone compound and a styryl compound. It is formed using a coating solution in which a charge transport material such as the above is dissolved in a resin solution containing a polycarbonate having a repeating unit represented by the formula (1). The ratio of the charge transport material to the resin is 20 to 200 parts by weight, preferably 50 to 150 parts by weight with respect to 100 parts by weight of the resin, and the film thickness is 5 to 40 μm, preferably 10 to 30 μm. is there. The charge transport layer can contain various antioxidants, ultraviolet absorbers, surface improvers and the like.
[0024]
The polycarbonate having the repeating unit represented by the formula (1) can be synthesized using a bisphenol compound represented by the following formula (3).
[0025]
[Chemical formula 5]
(Wherein R _{1 to} R ₈ and R _{9 to} R ₁₈ have the same meanings as in the formula (1)).
[0026]
Specific examples of the bisphenol compound represented by the formula (3) are shown in Tables 1 and 2 below.
[0027]
[Table 1]
[0028]
[Table 2]
[0029]
The polycarbonate having a repeating unit represented by the above formulas (1) and (2) in the present invention is a dihydric phenol represented by the above formula (3) and a dihydric phenol represented by the following formula (4).
[Chemical 6]
(Wherein R _{19 to} R ₂₆ represent a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 17 carbon atoms, X is a single bond,
[0031]
[Chemical 7]
R _{27 to} R _{40 each} represents a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 17 carbon atoms. ) Can be copolymerized.
[0032]
The dihydric phenol compound represented by the formula (4) include 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z; BPZ) and 1,1-bis (4-hydroxyphenyl ) -3,3,5-trimethyl cyclohexane.
[0033]
The polycarbonate used in the present invention is synthesized by reacting the bisphenol compounds of the above formulas (3) and (4) with phosgene in the presence of an oxygen binder and a solvent. Pyridine or sodium hydroxide is used as the oxygen binder, and dichloromethane, chlorobenzene, or the like is used as the solvent. In order to accelerate the condensation polymerization reaction, a tertiary amine such as triethylamine may be added, and a polymerization terminator such as phenol or pt-butylphenol may be added to adjust the molecular weight. In order to prevent oxidation of the bisphenol compound, it is preferable to add a reducing agent such as hydrosulfite.
[0034]
In addition, the solubility to a solvent and coating property can be changed into a desired state by blending a known polycarbonate together with the silicon-containing polycarbonate of the present invention .
[0035]
In addition, although the compounding ratio in the case of blending these well-known polycarbonates can be set arbitrarily, it is preferable to exist in the range of silicon-type polycarbonate: well-known polycarbonate = 0.01: 99.99-90: 10.
[0036]
FIG. 1 shows a schematic configuration of a process cartridge and an electrophotographic apparatus using the electrophotographic photosensitive member of the present invention.
[0037]
In the figure, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotated about a shaft 2 in the direction of an arrow at a predetermined peripheral speed. In the rotation process, the photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by the primary charging unit 3, and then from an image exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The image exposure light 4 is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor 1.
[0038]
The formed electrostatic latent image is then developed with toner by the developing unit 5, and the developed toner developed image is rotated between the photosensitive member 1 and the transfer unit 6 from a sheet feeding unit (not shown). The image is sequentially transferred by the transfer means 6 to the transfer material 7 that is synchronously taken out and fed.
[0039]
The transfer material 7 that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means 8, and subjected to image fixing, thereby being printed out as a copy (copy).
[0040]
After the image transfer, the surface of the photoreceptor 1 is cleaned by removing the transfer residual toner by the cleaning unit 9 and further subjected to charge removal processing by the pre-exposure light 10 from the pre-exposure unit (not shown), and then repeatedly. Used for imaging. When the primary charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.
[0041]
In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the primary charging unit 3, the developing unit 5 and the cleaning unit 9 described above are integrally coupled as a process cartridge. May be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the photosensitive member 1 to form a cartridge, and can be attached to and detached from the apparatus main body using guide means such as a rail 12 of the apparatus main body. The process cartridge 11 can be obtained.
[0042]
Further, when the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is a reflected light or transmitted light from a document, or a document is read by a sensor and converted into a signal. Light emitted by scanning, LED array driving, liquid crystal shutter array driving, and the like.
[0043]
The electrophotographic photosensitive member of the present invention can be used not only in electrophotographic copying machines but also widely in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.
[0044]
The synthesis of polycarbonates used Oite below in Example 1 below.
[0045]
Synthesis Example 1
0.1 mol each of the bisphenol compound of the following structural formula (3-1) and the bisphenol compound of (4-1), 0.2 mol in total.
Embedded image
[0047]
The above substances are put in a reaction vessel, and 40 g of phosgene is gradually added while stirring. At this time, since the reaction heat is large, stirring is performed while removing heat as necessary. Furthermore, 0.05 g of triethylamine, 10 g of sodium hydroxide, and 40 ml of water were added, and polymerization was performed within a range of 10 to 30 ° C. In addition, it wash | cleans with water in order to remove an impurity after superposition | polymerization completion. In this way, about 60 g of a silicon - containing copolymer polycarbonate was obtained.
[0048]
Example 1
5 parts by weight of conductive titanium oxide (tin oxide, antimony oxide coat, average primary particle size 0.4 μm), 5 parts by weight of high resistance titanium oxide (alumina coat, average primary particle size 0.4 μm), phenol resin precursor (resol) Mold) 10 parts by weight, 10 parts by weight of methanol and 10 parts by weight of butanol were dispersed in a sand mill, and this dispersion was applied by dip coating to an aluminum cylinder having an outer diameter of 30 mm and a length of 254 mm, and heat-cured to give a volume resistance of 5 × 10 A conductive layer having a thickness of ⁹ Ωcm and a thickness of 20 μm was formed.
[0049]
Next, methemoglobin Kishimechiru nylon resin (methoxymethyl degree of about 30%) 3 parts by weight,
[0050]
After 9 parts by weight of 6/66/610/12 quaternary copolymer nylon resin and 150 parts by weight of isopropanol were mixed and dissolved, the solution was dip-coated on the conductive layer to form an undercoat layer of 1 μm.
[0051]
Next, 10 parts by weight of an azo pigment represented by the following structural formula,
[0052]
Embedded image
5 parts by weight of a poly (vinyl acetate-vinyl alcohol-vinyl benzal) copolymer
In addition, 700 parts by weight of cyclohexanone was dispersed in a sand mill, and this dispersion was dip-coated on the undercoat layer to form a charge generation layer having a thickness of 0.05 μm.
[0054]
Next, 10 parts by weight of a triphenylamine compound represented by the following structural formula,
[0055]
Embedded image
10 parts by weight of the polycarbonate according to Synthesis Example 1 was dissolved in 75 parts by weight of chlorobenzene and dichloromethane, and this coating solution was dip-coated on the charge generation layer and dried with hot air to form a charge transport layer having a thickness of 25 μm. The electrophotographic photosensitive member of Example 1 was formed.
[0056]
Next, this photoconductor is mounted on a laser beam printer (Laser Jet4 manufactured by Hewlett-Packard Co. (primary charging is a DC voltage superimposed on an AC voltage)), and 10,000 sheets are continuously output. And the amount of surface layer scraping was measured. In addition to this, in order to remove the factor of the electric load due to the primary charging to the photosensitive member, the primary charging voltage was turned off, and the amount of surface layer scraping after continuous output of 10,000 sheets was measured. . These results are shown in Table 3 below.
[0057]
(Comparative Example 1)
A photoconductor was prepared and evaluated / measured in the same manner as in the photoconductor of Example 1 except that the binder resin for the charge transport layer was only 10 parts by weight of a commercially available polycarbonate . The results are shown in Table 3 below.
[0058]
(Comparative Example 2)
A photoconductor was prepared and evaluated / measured in the same manner as in the photoconductor of Example 1 except that only 10 parts by weight of a commercially available styrene-methyl methacrylate copolymer resin was used as the binder resin for the charge transport layer. The results are shown in Table 3 below.
[0059]
[Table 3]
[0060]
【The invention's effect】
As described above, according to the present invention, by using a polycarbonate having a repeating unit of the above formula (1) as a binder resin for at least the surface layer of the photoreceptor, a high mechanical film strength found in known polycarbonates can be obtained. While maintaining, excellent electric load resistance can also be imparted. Therefore, not only the durability of the electrophotographic photosensitive member can be improved, but also the adverse effect on the image due to the abrasion of the photosensitive member can be reduced, and the life of the photosensitive member can be dramatically improved. The effect is also exhibited in a process cartridge and an electrophotographic apparatus using this electrophotographic photosensitive member.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a schematic configuration of a process cartridge and an electrophotographic apparatus using an electrophotographic photosensitive member of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor of this invention 2 Axis 3 Primary charging means 4 Image exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail

Claims (1)

A charging means for charging the electrophotographic photosensitive member by contacting the electrophotographic photosensitive member and applying a DC voltage superimposed on an AC voltage, and image exposure is performed on the charged electrophotographic photosensitive member to perform electrostatic latent. In an electrophotographic apparatus, comprising: an image exposing means for forming an image; and a developing means for developing the electrophotographic photosensitive member on which an electrostatic latent image is formed with a toner.
Repeating unit said electrophotographic photosensitive member is, on a conductive support and have a photosensitive layer, at least the surface layer, and a repeating unit represented by the following formula (1), represented by the following formula (2) When an electrophotographic apparatus, wherein an electrophotographic photoreceptor containing a polycarbonate copolymer having:
(In the above formula (1), R _{1 to} R ₈ represent a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 17 carbon atoms, and R _{9 to} R ₁₈ represent a hydrogen atom, a halogen atom or carbon number 1 to 1). Represents 17 hydrocarbon groups);
(In the above formula (2), R ₁₉ to R ₂₆ represents a hydrocarbon group of a hydrogen atom, a halogen atom or a carbon number 1 to 17, X is
The stands, R ₂₉ to R ₃₈ are a hydrogen atom, a halogen atom or carbon atoms represent 1-17 hydrocarbon group).