JP5472592B2 - Electrophotographic photoreceptor - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member used for a copying machine, a laser printer, and the like, an image forming apparatus using the same, and a process cartridge, and more particularly to an electrophotographic photosensitive member using an organic thin film.

Conventionally, a thin film made of a material such as selenium, selenium-tellurium, selenium-arsenic, amorphous silicon or the like has been used as a photosensitive layer in an electrophotographic photosensitive member used in a copying machine, a laser printer, or the like.
However, in recent years, those using organic photoreceptors that are low in cost and have little environmental pollution are becoming mainstream. Such organic photoreceptors can be classified into a single-layer dispersion type photosensitive layer and a function-separated type photosensitive layer when classified by the structure of the photosensitive layer.

A monolayer dispersion type photoconductor is obtained by dispersing a charge generating agent in a medium of a charge transfer agent and having a function of both charge generation and charge transfer in a single layer film. A charge generation layer (CGL) that generates charges and a charge transfer layer (CTL) that moves the generated charges are formed separately. At present, both types of electrophotographic photoreceptors are in practical use.
Organic photoconductors can be classified into two types: positively charged and negatively charged. Among the currently known electron transfer agents, most of those with high mobility are those with hole mobility. In addition, since there is a lot of room for selection of materials, it is easy to control the characteristics of the photoconductor, and as a practical organic photoconductor, a laminated negative belt photoconductor is the mainstream.

On the other hand, a single-layer type photoreceptor has not only a small coating process and is advantageous in terms of cost, but also has an advantage that interference fringes in monochromatic light such as laser light hardly occur.
Furthermore, since incident light is almost absorbed near the surface of the photosensitive layer and charges are generated, there is almost no diffusion of irradiated light in the photosensitive layer, and the distance of charge movement until neutralization of the surface charge after charging is laminated. There are few points compared to the type of photoreceptor.
For this reason, resolution reduction due to diffusion of light and electric charges hardly occurs, and high-definition image formation is possible.
In addition, in a single layer type electrophotographic photosensitive member containing an electron transfer agent and a hole transfer agent in the photosensitive layer, it can be used in both positive and negative polarities, expanding the application range of the photosensitive member. Also, it is advantageous in reducing cost and speeding up by reducing the number of photoconductors.
In addition, the effect of ozone can be reduced when used with positive charging.

However, although it is a single layer type photoreceptor having such advantages, it is put into practical use only in the positively charged type, and the negatively charged type single layer photoreceptor is not put into practical use.
Also, no positively chargeable single-layer photoconductor that has both chargeability and photoconductor sensitivity comparable to those of a negatively charged laminated photoconductor has been obtained. This is because the single-layer photoconductor needs to have the function of moving electrons and holes in the same film, and also has a charge generation function in the same film, so it is difficult to develop materials and combine materials that fulfill each function. .
Electron transfer is carried out by an electron transfer agent, but a material that achieves high carrier transfer like a hole transfer agent has not been developed.
Furthermore, some electron transfer agents used in single-layer photoreceptors form charge transfer complexes with each other depending on the combination of materials, and the solubility and light transmission properties are significantly reduced. Compatibility between hole transfer agents and electron transfer agents exists. Is very important, and the standard for selecting an electron transfer agent and a hole transfer agent was not clear.

At present, as an electron transfer agent that can be used for a single layer type photoreceptor, trinitrofluorenone (TNF), tetracyanoethylene, tetracyanoquinodimethane (TCNQ), quinone, diphenoquinone, naphthoquinone, anthraquinone and Only substances with insufficient properties such as these derivatives have been found.
Specifically, these electron transfer agents have the following drawbacks.
(1) Most of these electron transfer agents have poor compatibility with the binder resin and cannot be uniformly dispersed at a high concentration in the photosensitive layer, so that the electrical characteristics cannot be satisfied due to insufficient content. .
(2) TNF has a high electron-accepting property and therefore has a high mobility, but is not suitable for practical use because of its high toxicity.
(3) Although TCNQ exhibits extremely high electron acceptability, it is strongly colored, and therefore, when a photosensitive layer is formed, it absorbs light that should originally reach the charge generating agent and lowers sensitivity. Toxicity is also a problem.
(4) In the diphenoquinone skeleton, an asymmetrically substituted compound has been proposed in order to improve the compatibility. However, a compound having sufficient performance for producing a highly sensitive positively charged electrophotographic photoreceptor has not been obtained. Absent.
Therefore, in order to improve this, in Patent Document 1 and Patent Document 2, 3-chloro-5, 3 ′, 5′-tri-tert-butyldiphenoquinone is used as a den transport material as an asymmetrically substituted compound. Proposed.
(5) However, the combination with the hole transfer agent does not satisfy the sufficient characteristics in the durability of charging-exposure.
(6) Since the electron mobility is low, satisfactory sensitivity cannot be obtained in a negatively charged single layer photoreceptor.
As described above, the sensitivity and stability of the photoreceptor (charge-exposure by combining an electron transfer agent and a hole transfer agent to realize a single-layer photoreceptor that can be applied in both positive and negative polarity at present. No satisfactory product has been obtained in terms of the stability of repetition.

  It is an object of the present invention to provide a single-layer photoreceptor that can be used with high sensitivity and in both polarities, eliminating the drawbacks of the prior art.

The said subject is solved by following (1)-( 9 ) of this invention.
(1) “A single-layer electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer contains a diphenoquinone compound represented by the following general formula (1) as an electron transfer agent, In addition, it contains a hole transfer agent represented by the following general formula (2), and also contains titanyl phthalocyanine as a charge generating agent. The titanyl phthalocyanine has a diffraction angle (2θ ± 0.2 °) with respect to CuKα rays of 27. An electrophotographic photosensitive member having a maximum peak at 3 ° .

（式中Ｒ_１、Ｒ_２、Ｒ_３は飽和炭化水素であって、相互に同じであっても異なっていても
よい。

(Wherein R ₁ , R ₂ and R ₃ are saturated hydrocarbons and may be the same or different from each other.

（式中、Ｒ_４〜Ｒ_５は、各々独立に水素、ハロゲン原子、置換基を有してもよい炭素数１〜６のアルキル基、炭素数１〜６のアルコキシル基を表わす。）」、
（２）「前記一般式（１）で表わされるジフェノキノン化合物は、下記式（１ａ）で示される化合物であることを特徴とする前記第（１）項に記載の電子写真感光体。

(Wherein R _{4 to} R ₅ each independently represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms).
(2) The electrophotographic photosensitive member according to item (1), wherein the diphenoquinone compound represented by the general formula (1) is a compound represented by the following formula (1a).

（前記式（１ａ）において、ｔ−Ｂｕは、ｔｅｒｔ−ブチル基を表わす。）」、
（３）「前記一般式（２）で表わされる正孔移動剤が下記式（２ａ）で表わされる構造を有する正孔移動剤であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」、

(In the formula (1a), t-Bu represents a tert-butyl group.) "
(3) The above-mentioned item (1) or (2), wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2a) Electrophotographic photosensitive member according to item) ”,

（４）「前記一般式（２）で表わされる正孔移動剤が下記式（２ｂ）で表わされる構造を有する正孔移動剤であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」、

(4) The above-mentioned item (1) or (2), wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2b) Electrophotographic photosensitive member according to item) ”,

（５）「前記一般式（２）で表わされる正孔移動剤が下記式（２ｃ）で表わされる構造を有する正孔移動剤であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」

(5) The above-mentioned item (1) or (2), wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2c) The electrophotographic photosensitive member according to the item)

（６）「前記一般式（２）で表わされる正孔移動剤が下記式（２ｄ）で表わされる構造を有する正孔移動剤であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」、

(6) The above-mentioned item (1) or (2), wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2d) Electrophotographic photosensitive member according to item) ”,

（７）「前記一般式（２）で表わされる正孔移動剤が下記式（２ｅ）で表わされる構造を有する正孔移動剤であることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」、

(7) The above-mentioned item (1) or (2), wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2e) Electrophotographic photosensitive member according to item) ”,

（８）「電子写真感光体、帯電手段、静電像形成手段、現像手段及び現像されたトナー像を転写する転写手段を有する画像形成装置において、前記電子写真感光体が、前記第（１）項乃至第（７）項のいずれかに記載の電子写真感光体であることを特徴とする画像形成装置」、
（９）「帯電手段、静電像形成手段、現像手段及び現像されたトナー像を転写する転写手段のうちの少なくとも１つの手段と前記第（１）項乃至第（７）項のいずれかに記載の電子写真感光体とを有し、画像形成装置に搭載可能なプロセスカートリッジ。」。

( 8 ) "In an image forming apparatus having an electrophotographic photosensitive member, a charging unit, an electrostatic image forming unit, a developing unit, and a transfer unit that transfers a developed toner image, the electrophotographic photosensitive member is the first (1). An image forming apparatus comprising the electrophotographic photosensitive member according to any one of items 1 to ( 7 ),
( 9 ) "At least one of charging means, electrostatic image forming means, developing means, and transfer means for transferring the developed toner image, and any of the above-mentioned items (1) to ( 7 )" And a process cartridge that can be mounted on an image forming apparatus.

  The optimum combination of a specific electron transfer agent and a specific hole transport agent allows efficient transfer of holes and electrons, and provides high sensitivity and repeated charge stability. By using the body, it can be applied to an image forming apparatus with stable image quality and high speed.

Sectional view of positively charged single layer type electrophotographic photosensitive member of an example of the present invention X-ray diffraction pattern of titanyl phthalocyanine used in the present invention Another X-ray diffraction pattern of titanyl phthalocyanine used in the present invention It is a figure for demonstrating an example of the image forming apparatus of this invention. FIG. 3 is a view for explaining an example of a process cartridge for an image forming apparatus according to the present invention.

Although it has been conventionally performed that the electron-transfer agent is substituted with an electron-withdrawing group, a compound containing an electron-withdrawing group increases the cohesive force of the electron-transfer agent itself. Thus, the compatibility of the photosensitive layer was deteriorated, so that it could not be dispersed at a high concentration in the photosensitive layer and was not put into practical use.
In order to improve the compatibility, as described above, it is generally said that the electron transfer agent should have an asymmetric structure. In the prior art, for example, an electron transfer agent having the following asymmetric structure has been proposed. .

（前記化学式（３）において、Ｍｅはメチル基、ｔ−Ｂｕは、ｔｅｒｔ−ブチル基を表わす。）
しかしながら、上記化学反応で得られる上記式（３）の電子移動剤は、同じ置換基が２個存在しており、完全な非対称構造とはなっておらず、電子移動度も低い。

(In the chemical formula (3), Me represents a methyl group, and t-Bu represents a tert-butyl group.)
However, the electron transfer agent of the above formula (3) obtained by the above chemical reaction has two identical substituents, does not have a completely asymmetric structure, and has a low electron mobility.

When an electron-withdrawing group is introduced into such an incompletely asymmetric structure of the electron transfer agent to improve the electron mobility, the compatibility obtained by the asymmetric structure is canceled by the cohesive force of the introduced electron-withdrawing group. It will be.
For example, the known electron transfer agent represented by the following formula (4) is only practically soluble in the binder resin and is not practical.

As a result of intensive studies, the present inventor, in particular, if the diphenoquinone compound is a specific diphenoquinone compound having a completely asymmetric structure without any symmetry axis, the compatibility with the binder resin is good even when an electron withdrawing group is introduced. It was also found that when a specific hole-transfer agent used in combination with this was selected and used, particularly good electrophotographic photoreceptor characteristics were exhibited.
That is, the diphenoquinone compound has the structure of the general formula (1).

Specifically, when R ₁ , R ₂ , and R ₃ are saturated hydrocarbons and are the same or different from each other, the diphenoquinone compound represented by the general formula (1) has high electron mobility. Because of its good compatibility with the binder resin, when used as an electron transfer agent, a highly sensitive electrophotographic photoreceptor can be obtained by uniformly dispersing it in the photosensitive layer at a high concentration.
Specific examples of the saturated hydrocarbon group represented by such substituents R ₁ , R ₂ , and R ₃ include linear saturated hydrocarbon groups such as a methyl group, an ethyl group, and a propyl group, an isopropyl group, and an isobutyl group. Groups, sec-butyl groups, tert-butyl groups, branched saturated hydrocarbon groups such as tert-pentyl groups, cyclic saturated hydrocarbon groups such as cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc. It can be used without being limited by the number of carbon atoms or its structure, such as a composite substituent between branched and cyclic saturated hydrocarbon groups.
Further, by bringing HCl gas into contact with a liquid in which a compound represented by the following formula (5) in which all the substituents are tert-butyl groups is uniformly dissolved, the complete formula represented by the following formula (1a) can be easily obtained. Asymmetric diphenoquinone compounds can be synthesized.

  Note that an effective charge transfer agent for a specific charge transfer agent is not necessarily effective for other charge transfer agents, and conversely, an effective charge generation for a specific charge transfer agent. It is known that the agent is not always effective against other electron transfer agents and has compatibility.

The charge transfer agent comprising a combination of the diphenoquinone compound (electron transfer agent) represented by the general formula (1) and the hole transfer agent of the general formula (2) is a charge generating agent comprising a disazo pigment and titanyl phthalocyanine, particularly titanyl phthalocyanine. In particular, it is best to use titanium phthalocyanine having a strong peak at a Bragg angle (2θ ± 0.2 °) of 27.2 ° in Cukα characteristic X-ray diffraction (see FIG. 2).
Further, titanium phthalocyanine having broad peaks at Bragg angles (2θ ± 0.2 °) of 7.6 ° and 28.6 ° in Cukα characteristic X-ray diffraction can be used (see FIG. 3). Titanium phthalocyanine having broad peaks at 7.6 ° and 28.6 ° does not have other characteristic clear peaks. In addition, the peak may become broad (spread), split (split), or shift (change in angle) depending on the crystal state or measurement conditions.
The concentration of the charge generating material in the photosensitive layer (3) in FIG. 1 is generally 0.005 wt% or more and 70 wt% or less, preferably 0.5 wt% or more and 5 wt% or less. When the concentration of the charge generating material is low, the photoreceptor sensitivity tends to decrease, and when the concentration is high, the chargeability and film strength tend to decrease.

Hereinafter, various examples of the hole transfer agent used in the photoconductor of the present invention may be mentioned. Of these, the compounds represented by the chemical formulas (2a) to (2e) have been found to be particularly preferable.
These are not well-established as being particularly excellent from many viewpoints among the many hole transfer agents. In fact, many of the prior arts using these as comparative examples are also found, and thus this fact is related to the electron transfer agent of the general formula (1) and the hole transfer agent of the general formula (2) in the present invention. It can be said that it is one aspect which shows the difficulty of prediction of the charge transfer agent which consists of a combination.

  One type of compounds represented by the above formulas (2a) to (2e) may be contained in the photosensitive layer, or two or more types may be used.

  The concentration of the hole transfer agent in the photosensitive layer (3) is not particularly limited because it varies depending on the required photoreceptor performance and charging polarity, but it is preferably 0.1% by weight or more and 70% by weight or less. If the concentration is low, hole movement may be insufficient, which may affect the characteristics of the photoconductor. If the concentration is high, the compatibility with the resin may deteriorate, resulting in a non-uniform film or low resin concentration. The film strength may decrease.

The conductive substrate of the present invention includes a single metal such as aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum and indium, a processed body of an alloy thereof, It is possible to use plastic plates and films that have been made conductive by depositing a conductive material such as carbon by a method such as vapor deposition or plating, and conductive glass coated with tin oxide, indium oxide, or aluminum iodide. .
Various materials having conductivity can be used without being limited by the type and shape of the conductive substrate.
In general, a cylindrical aluminum tube alone, a surface of which is anodized, or a material coated with a conductive resin is often used.

As the charge generating agent that can be used in the electrophotographic photosensitive member of the present invention, the above-mentioned disazo pigment and titanyl phthalocyanine are desirable in terms of good sensitivity compatibility, but are not limited thereto, and other examples include selenium, Selenium-tellurium, selenium-arsenic, amorphous silicon, other phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, polyazo pigments, indigo pigments, selenium pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, pyrylium salts, etc. Can be used.
These charge generating agents may be used alone or in combination of two or more in order to obtain an appropriate photosensitivity wavelength and sensitizing action.

Moreover, R < ₁ > -R < ₃ > in the said General formula (1) is not limited to a tert- butyl group, For example, if it is a methyl group, the compound shown by following formula (1b) will be an electron transfer agent. As obtained.

Moreover, the diphenoquinone compound shown by the said Chemical formula (1) may be used individually by 1 type, and 2 or more types may be mixed and used for it.
Further, the diphenoquinone compound represented by the general formula (1) is preferably contained in the photosensitive layer at a concentration of 0.1 wt% to 80 wt%.
Is obtained as an electron transfer agent.

  Furthermore, other electron transfer agents can be added to the electron transfer agent represented by the general formula (1). In that case, the sensitivity can be increased or the residual potential can be decreased. The characteristics of the electrophotographic photoreceptor of the present invention can be improved.

  Electron transfer agents and hole transfer agents that can be added to improve properties include polymer compounds such as polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl. Pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, polyisothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, polyphthalocyanine, etc. The conductive polymer compound can be used.

  As low molecular weight compounds, polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, nitrogen-containing heterocyclic compounds such as indole, carbazole, imidazole, fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, hydrazone, triphenylmethane, Triphenylamine, enamine, stilbene compounds and the like can be used.

  Further, a polymer solid electrolyte in which a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylic acid or the like is doped with a metal ion such as Li ion can also be used.

  Furthermore, an organic charge transfer complex formed of an electron donating compound typified by tetrathiafulvalene-tetracyanoquinodimethane and an electron accepting compound can also be used. Desired photoreceptor characteristics can be obtained even when these compounds are mixed and added.

  Binder resins that can be used to form the photosensitive layer include polycarbonate resin, styrene resin, acrylic resin, styrene-acrylic resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, chlorinated polyether, vinyl chloride. -Vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diarylate resin, polysulfone resin, polyethersulfone resin, poly Photocurable resins such as allyl sulfone resin, silicon resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, EVA resin, ACS resin, ABS resin, and epoxy arylateThese may be used alone or as a copolymer, or they may be used in combination of two or more. Further, it is preferable to use a mixture of resins having different molecular weights because the hardness and wear resistance can be improved.

  Solvents used in the coating solution include alcohols such as methanol, ethanol, n-propanol, i-propanol, and butanol, saturated aliphatic hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane, cycloheptane, toluene, Aromatic hydrocarbons such as xylene, chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, methoxyethanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, Esters such as ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, N, N-dimethylformamide, dimethyl sulfoxide, etc. . These may be used alone or as a mixture of two or more solvents.

  Addition of antioxidants, ultraviolet absorbers, radical scavengers, softeners, curing agents, crosslinking agents, etc. to the coating solution for producing the photoreceptor of the present invention within the range not impairing the electrophotographic photoreceptor characteristics It is possible to improve the characteristics, durability, and mechanical characteristics of the photoreceptor.

  Furthermore, the addition of dispersion stabilizers, anti-settling agents, anti-color separation agents, leveling agents, antifoaming agents, thickeners, matting agents, etc. can improve the finished appearance of the photoreceptor and the life of the coating solution. It is preferable.

In the electrophotographic photoreceptor of the present invention, an undercoat layer having an adhesion function, a barrier function, a defect covering function on the support surface, and the like may be provided between the conductive support and the photosensitive layer.
As the undercoat layer, aluminum oxide, polyethylene resin, acrylic resin, epoxy resin, polycarbonate resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, polyamide resin, nylon resin, or the like can be used.
These undercoat layers may be composed of a single resin or a mixture of two or more resins. Further, an undercoat layer in which a metal oxide or carbon is dispersed in a resin can be used.

  On the photosensitive layer, an organic thin film such as polyvinyl formal resin, polycarbonate resin, fluororesin, polyurethane resin, and silicon resin, or a thin film composed of a siloxane structure formed from a hydrolyzate of a silane coupling agent is formed. A surface protective layer may be provided, and in that case, the durability of the photoreceptor is improved, which is preferable. This surface protective layer may be provided in order to improve functions other than the durability improvement.

<Image forming apparatus>
Next, the image forming apparatus and the process cartridge image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 4 is a schematic diagram for explaining the electrophotographic process and the image forming apparatus of the present invention, and the following examples also belong to the category of the present invention.
As shown in FIG. 4, the photosensitive member (1) has a drum shape, but may have a sheet shape or an endless belt shape. For charging roller (12), pre-transfer charger (15), transfer charger (18), separation charger (19), pre-cleaning charger (21), in addition to corotron, scorotron, solid state charger (solid state charger) A roller-shaped charging member or a brush-shaped charging member is used, and all known means can be used.
As the charging member, a non-contact charging method such as corona charging or a contact charging method using a charging member using a roller or a brush is generally used, and any of them can be used effectively in the present invention. In particular, the charging roller can significantly reduce the amount of ozone generated compared to corotron, scorotron, etc., and is effective in stability and prevention of image quality deterioration when the photoreceptor is used repeatedly.
Examples of the light source such as the image exposure unit (13) and the charge removal lamp (11) include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). All of the luminescent materials can be used. Among these, a semiconductor laser (LD) and a light emitting diode (LED) are mainly used.
Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
As the transfer means, the above-described charger can be generally used. However, as shown in the figure, a combination of the transfer charger (18) and the separation charger (19) is effective.
Further, the toner image is directly transferred from the photosensitive member to the paper using such a transfer unit. In the present invention, the toner image on the photosensitive member is once transferred to the intermediate transfer member, and then from the intermediate transfer member to the paper. An intermediate transfer method for transferring the toner to the photoconductor is more preferable for enhancing the durability or improving the image quality of the photoreceptor.
The toner developed on the photoreceptor (1) by the developing unit (14) is transferred to the transfer paper (17), but not all is transferred, and the toner remaining on the photoreceptor (1). Also occurs.
Such toner is removed from the photoreceptor (1) by the fur brush (22) or the cleaning blade (23). This cleaning process may be performed only with a cleaning brush or may be performed in combination with a blade, and known cleaning brushes such as a fur brush and a mag fur brush are used. As described above, the cleaning is a process of removing the toner remaining on the photoreceptor (1) after the transfer.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge.
The process cartridge includes the photoelectric conversion element of the present invention, and further includes at least one of a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit, and is detachable from the image forming apparatus. This is a device (part).
A charging unit (12), a developing unit (14), and a cleaning unit) are arranged around the photoconductor (1) according to the present invention, and the developed toner image is transferred to the transferred transfer paper (17). An example of the process cartridge fitted and mounted on the transfer charger is shown in FIG. 8, but the neutralizing means is not described here.

  Hereinafter, the present invention will be described more specifically with reference to examples.

<Example of production of diphenoquinone>
First, an example of the manufacturing method of the diphenoquinone compound represented by the said General formula (1) used for this invention is demonstrated.
First, 91.8 g of potassium permanganate was added to a solution prepared by dissolving 30.0 g of 2,6-di-tert-butylphenol in 300 ml of chloroform, and the mixture was stirred for 25 hours while maintaining the temperature at 55 to 60 ° C.
Next, the inorganic substance was filtered off, concentrated and filtered. The obtained residue was dissolved in 100 ml of chloroform and recrystallized by adding a small amount of methanol to obtain diphenoquinone having a melting point of 242 to 243 ° C. as reddish brown crystals. . When the weight was measured, it was 21.5g, and it was 72% when converted into a yield.

Next, a mixed liquid of 300 ml of acetic acid and 120 ml of chloroform was prepared, and 3.0 g of the reddish brown crystals of diphenoquinone was dissolved as a reaction solvent, and kept at room temperature in a nitrogen atmosphere, and HCl gas was blown and reacted while stirring. .
After blowing in the HCl gas for 7 hours, the mixture was stirred overnight at room temperature, and the precipitate was separated by filtration. The filtrate was concentrated under reduced pressure, and then 300 ml of water was added and filtered to obtain 3.8 g of a yellow solid precipitate. When 3.8 g of the yellow solid precipitate was dissolved in 25 ml of methanol and recrystallized by adding a small amount of water, 2.4 g of diphenol having a melting point of 150 to 151 ° C. was obtained as pale yellow crystals. In terms of yield, it was 84%.

The 2.4 g of diphenol was dissolved in 180 ml of chloroform, 28.0 g of lead dioxide was added, and the mixture was stirred at room temperature for 3 hours, and then the residue was separated by filtration. The filtrate was concentrated and 20 ml of methanol was added. The precipitated crystals were filtered and washed with methanol to obtain 1.9 g of diphenoquinone represented by the above formula (1a) having a melting point of 155 to 156 ° C. as reddish purple crystals. In terms of yield, it was 81%.
The above reaction process is shown below.

以下の実施例で使用する前記式（１ａ）で示されたジフェノキノン化合物は、前記製造例の製造方法によって合成されたものである。一般式（１）で示される他のジフェノキノン化合物も、同様又は類似の方法により合成することができる。

The diphenoquinone compound represented by the formula (1a) used in the following examples is synthesized by the production method of the production example. Other diphenoquinone compounds represented by the general formula (1) can also be synthesized by the same or similar method.

<Example of production of titanyl phthalocyanine>
Into a mixture of 64.4 g of phthalodinitrile and 150 ml of α-chloronaphthalene, 6.5 ml of titanium tetrachloride was dropped for 5 minutes under a nitrogen stream. After dropping, the reaction was completed by heating at 200 ° C. for 2 hours with a mantle heater.
Thereafter, the precipitate was filtered, and the filtration residue was washed with α-chloronaphthalene, then washed with chloroform, and further washed with methanol.
Thereafter, a hydrolysis reaction was performed at a boiling point for 10 hours with a mixed solution of 60 ml of concentrated ammonia water and 60 ml of ion-exchanged water, followed by suction filtration at room temperature and washing with ion-exchanged water until the washing became neutral.
Then, after washing with methanol and drying with hot air at 90 ° C. for 10 hours, 64.6 g of blue-violet crystalline titanyl phthalocyanine powder was obtained.
Next, it was dissolved in about 10 times the amount of concentrated sulfuric acid, poured into water and precipitated, and 30 g of the filtered crude wet cake was washed with pure water until neutral, and filtered to obtain 29 g of titanyl phthalocyanine wet cake. .
10 g of the wet cake was put into 500 ml of tetrahydrofuran cooled to −5 ° C., stirred for 30 minutes, filtered and dried to obtain 9.5 g of titanyl phthalocyanine. The obtained titanyl phthalocyanine had an X-ray diffraction angle (2θ ± 0.2 °) with respect to Cu—Kα ray having a maximum diffraction angle of 27.3 ° as shown in FIG.
Further, 10 g of the wet cake was dried. The X-ray diffraction angle of the resulting titanyl phthalocyanine had broad peaks at (2θ) 7.5 ° and 28.8 ° as shown in FIG.

  An example of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. Referring to FIG. 1, (1) is a single-layer dispersion type electrophotographic photosensitive member according to an embodiment of the present invention, and includes a conductive substrate (2) made of a single cylindrical aluminum tube, and the conductive material. And a photosensitive layer (3) formed on the substrate (2).

In order to form the photosensitive layer (3) shown in FIG. 1, first, a paint shaker was used for 5 hours together with 0.5 g of titanyl phthalocyanine shown in FIG. 2 obtained by the following production example of titanyl phthalocyanine, 30 ml of glass beads and 320 ml of tetrahydrofuran. Disperse and filter the glass beads to obtain 308 ml of CGL solution.
To the obtained CGL liquid, 25.2 g of the hole transfer agent of the formula (2a), 25.2 g of the diphenoquinone of the formula (1a) obtained in the production example of the diphenoquinone, and 42 g of Z-type polycarbonate as a binder resin were added. Dissolved and prepared a coating for a single layer photoreceptor. A thin film with a thickness of 30 μm was applied on the conductive substrate (2) and dried at 120 ° C. for 1 hour to form the photosensitive layer (3). did.

  A photoconductor was prepared in the same manner as in Example 1 except that the hole transfer agent of the formula (2a) in Example 1 was changed to that of the formula (2b).

  A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one of formula (2a) was replaced with the hole transfer agent represented by formula (2c).

  A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one of formula (2a) was replaced with the hole transfer agent represented by formula (2d).

  A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one of formula (2a) was replaced with the hole transfer agent represented by formula (2e).

  A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one of formula (1a) was replaced with the electron transfer agent represented by formula (1b).

  In Example 1, the same procedure as in Example 1 was performed except that the charge transfer agent represented by formula (1b) was replaced by the charge transfer agent represented by formula (1b) and the formula (2a) was replaced by the hole transfer agent represented by formula (2b). A photoconductor was prepared.

  In Example 1, the same procedure as in Example 1 was performed except that the charge transfer agent represented by formula (1b) was replaced with the charge transfer agent represented by formula (1b) and the formula (2a) was replaced with the hole transfer agent represented by formula (2d). A photoconductor was prepared.

  A photoconductor was prepared in the same manner as in Example 1 except that the charge generator showing the XRD spectrum chart of FIG. 2 was replaced with the charge generator showing the XRD spectrum chart of FIG.

  In Example 1, except that the formula (2a) is replaced with the hole transfer agent of formula (2b), and the charge generator showing the XRD spectrum chart of FIG. 2 is replaced with the charge generator showing the XRD spectrum chart of FIG. Was prepared in the same manner as in Example 1.

  In Example 1, the formula (2a) was replaced with the hole transfer agent of formula (2d), and the charge generator showing the XRD spectrum chart of FIG. 2 was replaced with the charge generator showing the XRD spectrum chart of FIG. Was prepared in the same manner as in Example 1.

  A photoconductor was prepared in the same manner as in Example 1 except that the charge generator in FIG. 2 was replaced with the disazo pigment of the following formula (6) in Example 1.

  Example 1 is the same as Example 1 except that the formula (2a) is replaced by the hole transfer agent of formula (2b) and the charge generating agent showing the XRD spectrum chart of FIG. 2 is replaced by the disazo pigment of formula (6). A photoreceptor was prepared in the same manner as described above.

  Example 1 except that the formula (2a) is replaced with the hole transfer agent of formula (2d) and the charge generating agent showing the XRD spectrum chart of FIG. 2 is replaced with the disazo pigment of formula (6) in Example 1. A photoreceptor was prepared in the same manner as described above.

<Comparative Example 1>
In Example 1, a photosensitive layer was formed using diphenoquinone represented by the following formula (7) instead of diphenoquinone represented by the chemical formula (1a).

<Comparative example 2>
In Example 1, a photosensitive layer was formed using diphenoquinone represented by the above formula (7) instead of diphenoquinone represented by the chemical formula (1a).
A photoconductor was prepared in the same manner as in Example 1 except that the formula (2a) was replaced with the hole transfer agent of formula (2b).

<Comparative Example 3>
A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one represented by formula (2a) was replaced with the hole transfer agent represented by the following formula (8).

<Comparative Example 4>
A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one of formula (2a) was replaced with the hole transfer agent represented by the following formula (9).

<Comparative Example 5>
A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one represented by formula (2a) was replaced with a hole transfer agent represented by the following formula (10).

<Comparative Example 6>
A photoconductor was prepared in the same manner as in Example 1 except that in Example 1, the one represented by formula (2a) was replaced with a hole transfer agent represented by the following formula (11).

<Comparative Example 7>
In Example 1, the charge generating agent showing the XRD spectrum chart of FIG. 2 was replaced with the disazo pigment of formula (6), and the one of formula (2a) was replaced with the hole transfer agent represented by formula (11). A photoconductor was produced in the same manner as in Example 1.

<Comparative Example 8>
In Example 1, the charge generating agent showing the XRD spectrum chart of FIG. 2 was replaced with the disazo pigment of formula (6), and the one of formula (2a) was replaced with the hole transfer agent represented by formula (8). A photoconductor was produced in the same manner as in Example 1.

<Conditions for measuring electrical characteristics of single-layer dispersion type photoreceptor>
[Positive charge polarity evaluation method]
The corona discharger is set so that the corona discharge current is 20 μA, and the monolayer dispersion type photoconductors manufactured in Examples 1 to 14 and Comparative Examples 1 to 8 are positively charged by corona discharge in the dark. Measure the potential. The discharge current was adjusted so that the surface potential at this time was 700 V, and exposure was performed with light of 780 nm, and the exposure amount that reduced the surface potential of each photoconductor from 700 V to 350 was measured. Let the exposure amount at this time be a half exposure amount (μJ / cm ² ).
This half-exposure amount is a value indicating the sensitivity of the photoconductor. The smaller the half-exposure amount, the more sensitive the photoconductor, and the high-sensitivity photoconductor is 0.2 μJ / cm ² . 0.45 μJ / cm ² or less.
Further, the surface potential when each photoconductor was irradiated with 780 nm light (exposure energy 2 μJ / cm ² ) at a surface potential of 700 V was measured. The surface potential at this time is defined as a residual potential (VL).
This residual potential is a charge that does not decay after charging and remains on the surface of the photoreceptor without being completely discharged. Practically, the smaller the potential is, the more preferable it is 100 V or less.

[Negative charging characteristics evaluation method]
The charge polarity was switched to negative charge, and the evaluation was performed in the same manner as the above method.

<Measurement results>
The measurement results of Examples 1 to 14 and Comparative Examples 1 to 8 are as shown in Table 1.

<Evaluation results of photoconductor examples>
It can be seen that the photoreceptors of Examples 1 to 14 of the present invention have a high sensitivity of 0.1 to 0.25 μJ / cm ² and a low residual potential of 100 V or less.
On the other hand, since the electron transfer agents of Comparative Examples 1 and 2 have insufficient symmetry, charge transfer is poor and sufficient sensitivity cannot be obtained.
Comparative Examples 3 to 8 are combinations with other hole transfer agents, but here too, the compatibility between the electron transfer agent and the hole transfer agent is poor, the sensitivity is not sufficient, and the residual potential is poor.
The same was true when other charge generating agents of Comparative Examples 7 and 8 were used.

As described above, the combination of the electron transfer agent and the hole transfer agent used in the present invention has the following characteristics.
(1) The diphenoquinone compound, which is the electron transfer agent of the present invention, can be combined with the hole transfer agent of the present invention to obtain a highly sensitive positive / negative bipolar single layer type photoreceptor.
(2) By combining the titanyl phthalocyanine of FIG. 2 with the charge transfer agent comprising the combination of the electron transfer agent and the hole transfer agent of the present invention, high charge generation, high electron and hole transfer efficiency have never been achieved. A highly sensitive and charge-stable photoconductor can be obtained.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Conductive base | substrate 3 Photosensitive layer 11 Static elimination lamp 12 Charging roller 13 Image exposure part (image exposure means)
14 Development unit (development means)
15 Pre-transfer charger 16 Registration roller 17 Transfer paper 18 Transfer charger 19 Separation charger 20 Separation claw 21 Pre-cleaning charger 22 Fur brush 23 Cleaning blade

JP-A-9-62018 Japanese Patent Application No. 2008-02804

Claims (9)

A single-layer electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer contains a diphenoquinone compound represented by the following general formula (1) as an electron transfer agent, and the following general formula It contains a hole transfer agent represented by (2) and also contains titanyl phthalocyanine as a charge generator, and the titanyl phthalocyanine has a diffraction angle (2θ ± 0.2 °) with respect to CuKα rays at 27.3 °. An electrophotographic photoreceptor characterized by having a maximum peak .

(Wherein R ₁ , R ₂ and R ₃ are saturated hydrocarbons and may be the same or different from each other.

(In the formula, R _{4 to} R ₅ each independently represents hydrogen, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms.) 2. The electrophotographic photoreceptor according to claim 1, wherein the diphenoquinone compound represented by the general formula (1) is a compound represented by the following formula (1a).

(In the formula (1a), t-Bu represents a tert-butyl group.) 3. The electrophotographic photosensitive member according to claim 1, wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2a).

3. The electrophotographic photoreceptor according to claim 1, wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2b).

3. The electrophotographic photosensitive member according to claim 1, wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2c).

3. The electrophotographic photoreceptor according to claim 1, wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2d).

3. The electrophotographic photosensitive member according to claim 1, wherein the hole transfer agent represented by the general formula (2) is a hole transfer agent having a structure represented by the following formula (2e).

The image forming apparatus having an electrophotographic photosensitive member, a charging unit, an electrostatic image forming unit, a developing unit, and a transfer unit for transferring the developed toner image, wherein the electrophotographic photosensitive member is any one of claims 1 to 7. An image forming apparatus comprising the electrophotographic photosensitive member described above. It has at least one means among a charging means, an electrostatic image forming means, a developing means, and a transferring means for transferring the developed toner image, and the electrophotographic photosensitive member according to any one of claims 1 to 7 , A process cartridge that can be mounted in an image forming apparatus.

Images