JP4849080B2 - Electrophotographic photoreceptor, image forming apparatus and process cartridge - Google Patents

Description

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

  In recent years, the electrophotographic method has greatly expanded as a copier and printer technology. Electrophotographic photoreceptors used in electrophotography (hereinafter sometimes simply referred to as “photoreceptors”) have various degradations such as many contact mechanisms and stress mechanisms in the image forming process by electrophotography. Exposed to factors. Further, along with digitization and colorization, further high-speed reliability is required for electrophotographic photoreceptors.

  In the electrophotographic charging process, when the non-contact charging method is used, discharge products may adhere to the surface of the electrophotographic photoreceptor, and image blurring may occur. In order to remove discharge products, a polishing means may be employed in which particles having a polishing function are mixed in the developer and scraped off by a cleaning unit or the like. In this case, the surface of the photoreceptor deteriorates due to wear. In recent years, the contact charging method is widely used in the charging process, but wear may be accelerated by this method. From such a background, the electrophotographic photoreceptor is required to have a longer life.

  In order to extend the life of the electrophotographic photoreceptor, a high surface hardness is required from the viewpoint of wear resistance. If the surface of an electrophotographic photoreceptor is covered with high-hardness amorphous silicon, image blurring and image drift may occur due to discharge products adhering to the surface, especially at high humidity. It is often used as the surface layer of photographic photoreceptors. However, if a carbon-based film [for example, a hydrogenated amorphous carbon film (aC: H) or a fluorinated hydrogenated amorphous carbon film (aC: H, F)] has sufficient hardness, Therefore, as the surface wears, light transmission increases and sensitivity may increase. In addition, when wear occurs unevenly, the sensitivity is also uneven, and an influence may appear as image unevenness particularly in a halftone.

  As an attempt to extend the life of an electrophotographic photoreceptor by increasing the wear resistance of the electrophotographic photoreceptor surface, a proposal has been made to use a surface layer mainly composed of magnesium fluoride (for example, a patent). Reference 1).

  In addition, a proposal has been made to form an amorphous silicon carbide surface protective layer on the organic photosensitive layer by catalytic CVD (see, for example, Patent Document 2). Furthermore, it has also been proposed to improve the moisture resistance and printing durability of an electrophotographic photoreceptor by incorporating a small amount of gallium atoms in amorphous carbon (see, for example, Patent Document 3). On the other hand, an electrophotographic photoreceptor having a surface layer of amorphous carbon nitride having a diamond bond (see, for example, Patent Document 4) or non-single-crystal hydrogenated nitride semiconductor (for example, see Patent Document 5) has been proposed. ing.

On the other hand, diamond-like carbon and diamond films, which are carbon-based thin films, are widely researched and developed with the aim of applying them as semiconductor materials, wear resistant materials, low friction materials, gas barrier materials, electron emission materials, etc. Yes.
Similarly, research and development of carbon nitride films have been conducted in recent years.

  In addition, the present inventors have proposed a surface layer formed of a group 13 element and 15 atomic% or more of oxygen as the surface layer of the organic photoreceptor (see, for example, Patent Document 6).

Further, a hard surface layer formed by coating has been proposed. For example, an electrophotographic photoreceptor using a polymer compound having a siloxane bond as a surface layer has been proposed (see, for example, Patent Document 7).
JP 2003-29437 A JP 2003-316053 A Japanese Patent Laid-Open No. 2-110470 JP 2003-27238 A Japanese Patent Laid-Open No. 11-186571 JP 2006-267507 A JP 2006-267225 A

When a polymer compound having a siloxane bond is used for the surface layer, although there is an improvement in wear, the hardness is low, and the toner component tends to adhere when the scratches or wear occurs, and the life of the photoreceptor is reduced. There is.
In addition, when forming a surface layer using a method involving a temperature increase during film formation by sputtering, CVD method or the like, stress is generated in the surface layer due to thermal expansion of a base such as an organic photosensitive layer in the film formation process of the surface layer, The surface layer may be distorted. This distortion of the surface layer causes image unevenness when an image is formed by electrophotography.
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an electrophotographic photosensitive member in which image unevenness is unlikely to occur, and an image forming apparatus and a process cartridge using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the following problems can be solved by the present invention.

  That is, the invention according to claim 1 includes at least a conductive substrate, a subbing layer having a thickness of 5 μm to 50 μm in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, a group 13 element, and oxygen. And a surface layer having an element composition ratio of oxygen to a group 13 element of 0.9 to 1.4 in this order.

  The invention according to claim 2 includes at least a conductive substrate, a subbing layer having a thickness of 5 μm to 50 μm in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, a group 13 element, and nitrogen And a surface layer having an element composition ratio of nitrogen to a group 13 element of 0.4 or more and 0.8 or less in this order.

  The invention according to claim 3 is an electrophotographic photoreceptor in which the elemental composition ratio of oxygen in the outermost surface portion of the surface layer according to claim 1 or claim 2 to a group 13 element is 1.4 or more and 1.6 or less. It is.

  The invention according to claim 4 is the electrophotographic photoreceptor in which the surface layer according to any one of claims 1 to 3 further contains hydrogen.

The invention according to claim 5 is an electrophotographic photoreceptor according to claim 1 or 2,
Charging means for charging the surface of the electrophotographic photoreceptor;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor;
Image forming means for developing a latent electrostatic image formed on the surface of the electrophotographic photoreceptor using a developer containing at least a toner to form a toner image;
Transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the transfer target;
And a fixing unit that fixes the toner image transferred to the surface of the transfer target.

  A sixth aspect of the invention is an image forming apparatus in which the toner has a shape factor SF1 of 100 or more and 140 or less.

  The invention according to claim 7 is an image forming apparatus in which the developer according to claim 5 or 6 further includes a resin-coated carrier.

  According to an eighth aspect of the present invention, the image forming apparatus according to any one of the fifth to seventh aspects further includes a cleaning unit that removes residual toner on the surface of the electrophotographic photoreceptor after transfer. Forming device.

  The invention according to claim 9 is the image forming apparatus, wherein the cleaning means according to claim 8 is a cleaning blade.

  A tenth aspect of the present invention is an image forming apparatus in which the pressure contact force of the cleaning blade according to the ninth aspect to the surface of the electrophotographic photoreceptor is 5 gf / cm or more and 25 gf / cm or less.

  The invention according to an eleventh aspect is the image forming apparatus, wherein the cleaning means according to the ninth or tenth aspect further includes an electrostatic brush disposed on the upstream side of the cleaning blade.

  According to a twelfth aspect of the present invention, the toner image is formed on the downstream side of the image forming unit according to any one of the fifth to eleventh aspects and on the upstream side of the transfer unit. In addition, the image forming apparatus further includes a carrier collecting unit that collects illegal carriers transferred to the surface of the electrophotographic photosensitive member together with the toner by a magnetic force.

  A thirteenth aspect of the present invention is an image forming apparatus in which the charging unit according to any one of the fifth to twelfth aspects is a contact-type charger.

The invention according to claim 14 is the electrophotographic photoreceptor according to claim 1 or 2,
A charging means for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member, and a developer containing at least a toner. Image forming means for developing an electrostatic latent image formed on the surface of the photoconductor to form a toner image, and illegal carriers transferred to the electrophotographic photoconductor surface together with the toner when the toner image is formed are captured by magnetic force. Carrier collecting means for collecting, transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the transfer target, fixing means for fixing the toner image transferred to the surface of the transfer target, and after transfer And at least one selected from the group consisting of cleaning means for removing residual toner on the surface of the electrophotographic photoreceptor.
The process cartridge is removable from the main body of the image forming apparatus.

  According to the first aspect of the present invention, it is possible to obtain an electrophotographic photoreceptor that is less likely to cause image unevenness.

  According to the second aspect of the present invention, an electrophotographic photosensitive member that is less likely to cause image unevenness can be obtained.

  According to the invention of claim 3, it is possible to obtain an electrophotographic photoreceptor having an effect of preventing a reduction in image resolution.

  According to the invention which concerns on Claim 4, the surface energy of a surface layer can be made small, As a result, adhesion of a discharge product and a transfer residual toner can be suppressed.

  According to the fifth aspect of the present invention, an image forming apparatus capable of forming an image with little image unevenness can be obtained.

  According to the invention which concerns on Claim 6, a high-definition image can be formed.

  According to the seventh aspect of the present invention, it is possible to suppress the occurrence of scratches on the surface of the electrophotographic photoreceptor due to the minute carriers.

  According to the eighth aspect of the present invention, residual toner on the surface of the electrophotographic photoreceptor can be removed.

  According to the ninth aspect of the invention, the residual toner on the surface of the electrophotographic photoreceptor can be reliably removed with a simple configuration.

  According to the invention of claim 10, since the pressure contact force of the cleaning blade to the surface of the electrophotographic photoreceptor is small, the wear of the electrophotographic photoreceptor can be suppressed.

  According to the eleventh aspect of the present invention, it is possible to suppress the occurrence of scratches on the surface of the photoreceptor due to unauthorized carriers.

  According to the twelfth aspect of the present invention, it is possible to suppress the occurrence of scratches on the surface of the photoreceptor due to unauthorized carriers.

  According to the invention of claim 13, the amount of ozone generated when the surface of the electrophotographic photoreceptor is charged can be reduced.

  According to the fourteenth aspect of the present invention, it is possible to facilitate the handling of the electrophotographic photosensitive member that is less likely to cause image unevenness, and to improve the adaptability to image forming apparatuses having various configurations.

  Hereinafter, embodiments of the electrophotographic photoreceptor, the image forming apparatus, and the process cartridge of the present invention will be described in detail.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the first embodiment includes a conductive substrate, an undercoat layer having a thickness of 5 μm to 50 μm in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, and a group 13 element. And a surface layer containing at least oxygen and an elemental composition ratio of oxygen to a group 13 element of 0.9 or more and 1.4 or less. The elemental composition ratio of oxygen to the group 13 element is preferably 0.9 or more and 1.35 or less, and more preferably 0.95 or more and 1.3 or less.
An electrophotographic photoreceptor according to the second embodiment includes a conductive substrate, an undercoat layer having a thickness of 5 μm or more and 50 μm or less in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, 13 A surface layer containing at least a group element and nitrogen and having an elemental composition ratio of nitrogen to group 13 elements of 0.4 or more and 0.8 or less. The elemental composition ratio of nitrogen to the group 13 element is preferably 0.45 or more and 0.75 or less, and more preferably 0.5 or more and 0.7 or less.

  The electrophotographic photoreceptors according to the first embodiment and the second embodiment (hereinafter sometimes simply referred to as “the electrophotographic photoreceptor of this embodiment”) are made of a conductive filler in an organic polymer. An undercoat layer having a dispersed thickness of 5 μm or more and 50 μm or less is provided. If the thickness of the undercoat layer is less than 5 μm, the electrophotographic photosensitive member may have insufficient chargeability and repeatability. Furthermore, when the thickness of the undercoat layer is less than 5 μm, it occurs when forming a surface layer containing at least a group 13 element and oxygen or nitrogen and having an element composition of oxygen or nitrogen with respect to the group 13 element at a predetermined ratio. Due to the stress, traps are formed in the entire organic photosensitive layer, and the residual potential of the initial electrophotographic photoreceptor may be increased. This residual potential recovers even when left in the dark, but if the undercoat layer is less than 5 μm, it takes a long time to recover this electrical property by providing a surface layer, and partial recovery unevenness is likely to occur. As a result, image quality unevenness occurs and is not practical in terms of image quality.

  Even if it is a subbing layer having a thickness of 5 μm or more, a surface layer provided with a group 13 element oxide or nitride having a stoichiometric ratio requires a long time to recover electrical characteristics such as residual potential. Become. Further, although the value of the residual potential is within a practical range with an increase of about several tens of volts as compared to an electrophotographic photoreceptor without a surface layer, potential unevenness due to potential recovery unevenness is likely to occur in an image, and as a result. There is a problem that image quality unevenness occurs. This is because space charges are likely to be generated in the entire organic photosensitive layer, and the charges that have moved through the charge transport layer after light irradiation cannot be erased by the high-resistance surface layer, and thus accumulate in the charge transport layer. The cause is presumed to occur.

In contrast, the electrophotographic photoreceptor of the present embodiment in which the surface layer is provided with a surface layer whose composition is oxygen-deficient or nitrogen-deficient from the stoichiometric ratio and an undercoat layer of 5 μm or more is formed as a surface layer. In addition to reducing distortion in the photosensitive layer due to time stress, stable electrical characteristics in a short time after film formation, and uniform recovery of space charge erasure, practical halftone image for color image output Uniformity is obtained.
When the undercoat layer is made thicker than 50 μm, the residual potential and repeat characteristics due to the undercoat layer become insufficient, and a stable image may not be output by repeated use.

Further, when the charge transport layer is thinned as an electrophotographic photosensitive member for high image quality by adjusting the undercoat layer to 5 μm or more and 50 μm or less, the surface thickness can be adjusted by adjusting the thickness of the undercoat layer. Distortion due to residual stress during layer formation can be reduced. Moreover, the undercoat layer containing a conductive filler has a high stress relaxation effect.
An intermediate layer may be provided between the undercoat layer and the organic photosensitive layer from the viewpoint of improvement in hardness, expansion rate, and adhesion.

  The layer structure of the electrophotographic photoreceptor of this embodiment is not particularly limited as long as it comprises a conductive substrate, an undercoat layer, an organic photosensitive layer, and a surface layer in this order. Moreover, you may provide the other layer as needed. Hereinafter, a specific example of the layer configuration of the electrophotographic photoreceptor of the exemplary embodiment will be described in more detail.

  1 and 2 are cross-sectional views showing an example of the layer structure of the electrophotographic photoreceptor of this embodiment. 1 and 2, 1 is a conductive substrate, 2 is an undercoat layer, 3 is an organic photosensitive layer, 3A is a charge generation layer, 3B is a charge transport layer, and 4 is a surface layer.

  The organic polymer compound forming the organic photosensitive layer may be thermoplastic or thermosetting, or may be formed by reacting two types of molecules. In addition, an intermediate layer may be provided between the organic photosensitive layer and the surface layer from the viewpoint of adjusting hardness, expansion coefficient, elasticity, and improving adhesion. The intermediate layer preferably exhibits intermediate properties with respect to both the physical properties of the surface layer and the organic photosensitive layer (in the case of the function separation type, the charge transport layer). In the case where an intermediate layer is provided, the intermediate layer may function as a layer for trapping charges.

  The organic photosensitive layer may be a function-integrated type as shown in FIG. 1, or may be a function-separated type divided into a charge generation layer and a charge transport layer as shown in FIG. In the case of the function separation type, a charge generation layer may be provided on the surface side of the photoreceptor, or a charge transport layer may be provided on the surface side.

When a surface layer is formed on the organic photosensitive layer by a method described later, a surface layer is formed on the surface of the organic photosensitive layer in order to prevent the organic photosensitive layer from being decomposed by irradiation with a short wavelength electromagnetic wave other than heat. A short-wavelength light absorption layer such as ultraviolet rays may be provided in advance before the operation. Further, a layer having a small band gap can be formed first in the initial stage of forming the surface layer so that the short wavelength light is not irradiated onto the organic photosensitive layer. As the composition of the layer having a small band gap provided on the organic photosensitive layer side, for example, Ga _X In _(1-X) (0 ≦ X ≦ 0.99) is preferable as the group 13 element ratio including In.

A layer containing an ultraviolet absorber (for example, a layer formed by applying a layer dispersed in a polymer resin or the like) may be provided on the surface of the organic photosensitive layer.
As described above, by providing an intermediate layer on the surface of the photoreceptor before forming the surface layer, ultraviolet rays when forming the surface layer, corona discharge when the photoreceptor is used in the image forming apparatus, and various types of The influence on the organic photosensitive layer by short wavelength light such as ultraviolet rays from the light source can be prevented.

-Surface layer-
Next, the characteristics of the surface layer will be described in more detail.
The surface layer prevents scratches on the surface, guarantees uniform polishing, hardly adsorbs nitrogen oxides, etc., and has high resistance to oxygen in an oxidizing atmosphere with ozone or nitrogen oxides. . It is a highly transparent and dense film with excellent hardness.
The surface layer according to the present embodiment may trap surface charge on the surface or trap it inside. Further, a surface charge may be positively injected. In order to inject charges into the surface layer, it is necessary to trap the charges at the interface with the organic photosensitive layer. When the surface layer injects electrons under negative charge, the surface of the hole transport layer is charged. A trap function may be achieved, or a layer for blocking charge injection and trapping may be provided. The same applies to the case of positive charging.

The surface layer according to the present embodiment contains at least a group 13 element and oxygen or nitrogen, and the elemental composition ratio of oxygen to the group 13 element is 0.9 or more and 1.4 or less, or the elemental composition ratio of nitrogen to the group 13 element. Is 0.4 or more and 0.8 or less.
The surface layer according to the present embodiment is a group 13 oxide or nitride semiconductor containing a group 13 element and oxygen or nitrogen, has high hardness, retains a latent image, and prevents charge accumulation in the surface layer. Can be controlled. In addition, it has excellent oxidation resistance even in oxygen in the atmosphere or in an oxidizing atmosphere, and changes in physical properties over time are extremely small.

  The surface layer according to the present embodiment may be composed of only a group 13 element and oxygen or nitrogen, but in addition to this, a fourth element such as hydrogen may be included as necessary. In particular, hydrogen is preferably contained. In this case, hydrogen compensates for dangling bonds and structural defects generated by the bond between the group 13 element and oxygen, thereby increasing electrical stability, chemical stability, mechanical stability, and high hardness. In addition to transparency, a high water repellency and low friction coefficient on the surface layer surface can be obtained.

The composition in the thickness direction of the surface layer may be uniform, but if it contains a group 13 element and oxygen or nitrogen, the composition has a gradient structure in the thickness direction of the film, or has a multilayer structure. It may be a thing.
The concentration distribution of oxygen or nitrogen in the thickness direction of the surface layer decreases toward the substrate side, and the surface may have a stoichiometric ratio.
By reducing the amount of oxygen or nitrogen, the surface layer has high resistance toward the surface, high hardness, light absorption is reduced, the surface does not deteriorate the photoelectric characteristics of the organic photosensitive layer, and has excellent long-term stability. Become a layer.

  The stoichiometric ratio of the group 13 element to oxygen in the surface layer is 2: 3, and the stoichiometric ratio with nitrogen is 1: 1. In this embodiment, nitrogen or oxygen is in a deficient state. ing. The resistance of oxides or nitrides depleted in oxygen or nitrogen is lower than those in stoichiometric ratios. If the elemental composition ratio of oxygen or nitrogen to the group 13 element is less than 0.9 or less than 0.4, respectively, the electric resistance of the surface layer may be lowered and the electrostatic latent image may not be retained.

Furthermore, when the surface layer contains hydrogen, the surface energy on the outermost surface of the surface layer becomes small, so that adhesion of discharge products and transfer residual toner can be suppressed, and image defects due to the adhesion of discharge products are generated. Can also be suppressed. In addition, since the friction coefficient of the outermost surface of the surface layer is reduced, the progress of wear and the generation of scratches can be further suppressed.
Further, since the friction coefficient of the outermost surface of the surface layer is small, cleaning can be performed with a low torque when the transfer residual toner on the surface of the photoreceptor is removed by the cleaning blade. The cleaning blade is likely to damage the surface of the photosensitive member and promote wear compared to other cleaning means. However, since the surface of the electrophotographic photosensitive member of the present embodiment is smooth and slidable, it is possible to suppress the occurrence of scratches and abrasion on the surface of the photosensitive member even during long-term use.

The hydrogen content in the surface layer is preferably in the range of 0.1 atomic percent to 40 atomic percent, and more preferably in the range of 0.5 atomic percent to 30 atomic percent.
When the hydrogen content is less than 0.1 atomic%, structural disturbances remain built in the film, which may cause electrical instability and insufficient mechanical characteristics. In addition, when it exceeds 40 atomic%, the probability that hydrogen bonds to two or more atoms in the group 13 element increases, the three-dimensional structure cannot be maintained, and the hardness and chemical stability (especially water resistance) are not good. May be sufficient.

In the present embodiment, the hydrogen content in the surface layer means a value obtained by hydrogen forward scattering (HFS).
HFS used NEC 3SDH Pelletron as an accelerator, CE & A RBS-400 as an end station, and CE & A 3S-R10 as a system.
For the analysis, the CE & A HYPRA program was used.

The measurement conditions of HFS are as follows.
He ++ ion beam energy: 2.275 eV
A detection angle of 160 ° is Grazing Angle 30 ° with respect to the incident beam.

The HFS measurement can pick up the hydrogen signal scattered in front of the sample by setting the detector at 30 ° to the He ++ ion beam and the sample at 75 ° from the normal. At this time, the detector is preferably covered with a thin aluminum foil to remove He atoms scattered together with hydrogen. The quantification is performed by comparing the hydrogen counts of the reference sample and the sample to be measured after normalization with the stopping power. As a reference sample, a sample obtained by ion implantation of H into Si and muscovite were used.
It is known that muscovite has a hydrogen concentration of about 6.5 atomic%.
The H adsorbed on the outermost surface can be corrected by subtracting the amount of H adsorbed on the clean Si surface.

The surface layer may contain carbon, but the carbon content in this case is preferably 10 atomic% or less. In particular, when carbon is present as —CH ₂ or —CH ₃ , the amount of hydrogen contained in the surface layer increases, and as a result, the chemical stability of the surface layer in the atmosphere may be insufficient. is there.
Specifically, as the group 13 element contained in the surface layer, at least one element selected from B, Al, Ga, and In can be used, and two or more elements selected from these elements are combined. Can also be used.
In this case, the combination of the contents of these atoms in the surface layer is not limited, but among the above four elements, in the case of In nitride, there is absorption in the visible light region, and elements other than In are visible. Since there is no absorption in the light region, it is possible to arbitrarily adjust the sensitive wavelength region of the surface layer with respect to light by appropriately selecting the group 13 element to be used. In the surface layer according to the present embodiment, it is necessary to select an element so as not to absorb as much light as possible with respect to the exposure wavelength, the erase wavelength, and the like of the image forming apparatus provided with the photoconductor.

  In the present embodiment, the content of group 13 elements and elements such as nitrogen, oxygen, and carbon in the surface layer means values obtained by Rutherford back scattering (RBS) including distribution in the film thickness direction. .

  RBS used NEC 3SDH Pelletron as an accelerator, CE & A RBS-400 as an end station, and CE & A 3S-R10 as a system. The analysis used the CE & A HYPRA program.

The RBS measurement conditions are as follows.
He ++ ion beam energy: 2.275 eV
Detection angle 160 ° Grazing Angle 109 ° with respect to incident beam.

In the RBS measurement, a He ++ ion beam is incident on the sample perpendicularly, a detector is set at 160 ° with respect to the ion beam, and the backscattered He signal is measured. The composition ratio and the film thickness are determined from the detected energy and intensity of He.
In order to improve the accuracy of obtaining the composition ratio and the film thickness, the spectrum may be measured at two detection angles. Accuracy can be improved by measuring and cross-checking at two detection angles with different depth resolution and backscattering dynamics.
The number of He atoms back-scattered by the target atom is 1) the atomic number of the target atom, 2) the energy of the He atom before scattering, and 3) the scattering angle.
It is determined only by these three elements.
The density is assumed by calculation from the measured composition, and this is used to calculate the film thickness. The density error is within 20%.

  Here, the above-mentioned “element composition ratio of group 13 element to oxygen or nitrogen (oxygen or nitrogen / group 13 element)” refers to the film thickness direction of the surface layer excluding the range of 10 nm in depth from the outermost surface. Means an averaged value. The reason why the range of 10 nm from the outermost surface is not included is to eliminate the influence of carbon and the like due to contamination and to eliminate the influence of natural oxidation. Even if a stoichiometric insulating film is formed by natural oxidation at a depth within 10 nm from the outermost surface, there is almost no adverse effect on the electrical characteristics of the photoreceptor. Note that the element composition ratio may have a different value with respect to the film thickness direction in a region excluding the range of at least 10 nm in depth from the outermost surface. In this case, the “element composition ratio” means a value averaged with respect to the film thickness direction.

The crystallinity / non-crystallinity of the surface layer is not particularly limited, but may be any of microcrystal, polycrystal, or amorphous.
The surface layer may be amorphous including microcrystals or microcrystal / polycrystal including amorphous materials due to stability or hardness. Is preferably amorphous. Crystallinity / amorphous property can be determined by the presence or absence of a point or a line in a diffraction image obtained by RHEED (reflection high-energy electron diffraction) measurement. Amorphousness can also be determined by the absence of a sharp peak specific to the diffraction angle even by X-ray diffraction spectrum measurement.

  Various dopants can be added to the surface layer in order to control the conductivity type and the conductivity. When controlling the conductivity of the surface layer to n-type, for example, one or more elements selected from Si, Ge, and Sn can be used, and when controlling to p-type, for example, Be, Mg One or more elements selected from Ca, Zn and Sr can be used. In addition, normally undoped semiconductors have many n-types, and elements used for p-type conversion can be used to further increase dark resistance.

The surface layer according to the present embodiment has a bond defect, a dislocation defect, and a grain boundary defect in its internal structure regardless of whether the crystallinity / non-crystallinity is microcrystalline, polycrystalline, or amorphous. Etc. tend to be included. For this reason, hydrogen and / or a halogen element may be contained in the surface layer in order to inactivate these defects. Hydrogen and halogen elements in the surface layer are incorporated into bonding defects, etc., which eliminates reactive sites and performs electrical compensation, thereby suppressing traps related to carrier diffusion and movement in the surface layer. Is done.
Even when the surface layer according to the present embodiment is a thick film in order to maintain sufficient mechanical strength, the residual potential on the surface of the photoreceptor due to the internal accumulation of charges and the cycle up when charging and exposure are repeated And charging characteristics can be further stabilized.

  As described above, the surface layer may be either amorphous or crystalline. However, in order to improve the adhesion with the organic photosensitive layer (or the intermediate layer) and improve the slip of the photoreceptor surface, the surface layer Is preferably amorphous. Further, the lower layer (organic photosensitive layer side) of the surface layer may be microcrystalline, and the upper layer (photosensitive member surface side) may be amorphous.

The surface layer may be injected into the surface layer during charging. In this case, charges must be trapped at the interface between the surface layer and the organic photosensitive layer. Moreover, electric charges may be trapped on the surface of the surface layer. For example, when the organic photosensitive layer is a function separation type as shown in FIG. 2, when the surface layer injects electrons with negative charge, the surface of the charge transport layer on the surface layer side may serve as a charge trap. An intermediate layer may be provided between the charge transport layer and the surface layer for blocking and trapping charge injection. The same applies to the case of positive charging.
The thickness of the surface layer is preferably in the range of 0.01 μm to 5 μm. If the thickness is less than 0.01 μm, it is easily affected by the organic photosensitive layer, and the mechanical strength may be insufficient. If it is thicker than 5 μm, the residual potential increases due to repeated charging and exposure, and mechanical internal stress on the organic photosensitive layer increases, and peeling and cracking are likely to occur.

The surface layer may also function as a charge injection blocking layer or a charge injection layer. In this case, as described above, the surface layer can also function as a charge injection blocking layer or a charge injection layer by adjusting the conductivity type of the surface layer to n-type or p-type.
When the surface layer also functions as a charge injection layer, charges are trapped on the surface of the intermediate layer or the organic photosensitive layer (surface on the surface layer side). In the case of negative charging, the n-type surface layer functions as a charge injection layer, and the p-type surface layer functions as a charge injection blocking layer. In the case of positive charging, the n-type surface layer functions as a charge injection blocking layer, and the p-type surface layer functions as a charge injection layer.
In order to maintain the electrostatic latent image, an i-type semiconductor film having a high resistance may be formed as the surface layer. In this embodiment, the resistance is controlled by the ratio of oxygen or nitrogen atoms to group 13 atoms.

  In the present embodiment, the elemental composition ratio of oxygen in the outermost surface portion of the surface layer to the group 13 element is preferably 1.4 or more and 1.6 or less. Thereby, the effect of chemical stability and high water repellency can be obtained. In the present embodiment, the “outermost surface layer” refers to a portion up to 10 nm from the surface. The outermost surface composition can be measured using X-ray photoelectron spectroscopy (XPS). Although the carbon compound may be adsorbed on the outermost surface, Ar + sputtering may be performed. The outermost surface may be natural oxidation or a film may be produced.

-Conductive substrate-
Conductive substrates include metal drums such as aluminum, copper, iron, stainless steel, zinc, nickel; aluminum, copper, gold, silver, platinum, palladium, titanium, nickel on a substrate such as sheet, paper, plastic, glass, etc. -Deposited metal such as chromium, stainless steel, copper-indium; Deposited conductive metal compound such as indium oxide and tin oxide on the substrate; Laminated metal foil on the substrate; Carbon black Indium oxide, tin oxide-antimony oxide powder, metal powder, copper iodide, and the like are dispersed in a binder resin and applied to the substrate to conduct a conductive treatment. The shape of the conductive substrate may be any of a drum shape, a sheet shape, and a plate shape. In the present embodiment, “conductivity” means that the condition of 1000Ω / □ or less is satisfied.

  When a metal pipe base is used as the conductive base, the surface of the metal pipe base may be a raw pipe, but the base surface may be roughened by surface treatment in advance. It is. Such roughening can prevent grain-like density unevenness due to interference light that can be generated inside the photosensitive member when a coherent light source such as a laser beam is used as the exposure light source. Examples of the surface treatment method include mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing and the like.

  In particular, from the viewpoint of improving the adhesion to the organic photosensitive layer and improving the film-forming property, it is preferable to use an anodized surface of the aluminum substrate as described below as the conductive substrate.

Hereinafter, a method for producing a conductive substrate having an anodized surface will be described. First, pure aluminum or aluminum alloy (for example, alloy numbers 1000, 3000, and 6000 series aluminum or aluminum alloy defined in JISH4080) is prepared as a substrate. Next, an anodizing process is performed. The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but the treatment with a sulfuric acid bath is often used. The anodizing treatment is, for example, sulfuric acid concentration: 10 mass% to 20 mass%, bath temperature: 5 ° C. to 25 ° C., current density: 1 A / dm ^{2 to} 4 A / dm ² and electrolysis voltage: 5 V to 30 V. The treatment time is 5 to 60 minutes, but is not limited thereto.

  The anodized film formed on the aluminum substrate in this way is porous, has high insulating properties, and has a very unstable surface. Therefore, its physical properties change over time after the film is formed. It has become easier. In order to prevent the change of the physical property values, the anodized film is further sealed. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Of these methods, the method of immersing in an aqueous solution containing nickel acetate is most often used.

  On the surface of the anodic oxide film that has been subjected to the sealing treatment in this way, an excessive amount of metal salt or the like attached by the sealing treatment remains. If the metal salt or the like is excessively left on the anodic oxide film of the substrate, it not only adversely affects the quality of the coating film formed on the anodic oxide film, but generally tends to leave low resistance components. When an image is formed using this substrate as a photoconductor, it causes a background stain.

  Therefore, following the sealing process, an anodic oxide film is cleaned to remove metal salts and the like attached by the sealing process. The cleaning treatment may be performed by cleaning the substrate once with pure water, but the substrate is preferably cleaned by a multi-step cleaning process. At this time, a cleaning liquid that is as clean as possible (deionized) is used as the cleaning liquid in the final cleaning step. Moreover, it is more preferable to perform physical rubbing cleaning using a contact member such as a brush in any one of the multi-step cleaning steps.

  The film thickness of the anodized film on the surface of the conductive substrate formed as described above is preferably in the range of about 3 μm to 15 μm. On the anodized film, there is a layer called a barrier layer along the porous extreme surface of the porous anodized film. The thickness of the barrier layer is preferably in the range of 1 nm to 100 nm. As described above, an anodized conductive substrate can be obtained.

  The conductive substrate thus obtained has a high carrier blocking property in the anodized film formed on the substrate by anodization. Therefore, it is possible to prevent point defects (black spots, background stains) that occur when a photoconductor using this conductive substrate is mounted on an image forming apparatus and reversal development (negative / positive development) is performed, It is possible to prevent a current leakage phenomenon from a contact charger that is likely to occur during contact charging. Further, by subjecting the anodized film to a sealing treatment, it is possible to prevent a change in physical property values with time after the preparation of the anodized film. In addition, by washing the conductive substrate after the sealing treatment, metal salts and the like attached to the surface of the conductive substrate can be removed by the sealing treatment, and a photoconductor produced using this conductive substrate is provided. When an image is formed by the image forming apparatus, it is possible to prevent the occurrence of background stains.

-Undercoat layer-
Next, the undercoat layer will be described.
In the undercoat layer according to this embodiment, a conductive filler is dispersed in an organic polymer, and the thickness is 5 μm or more and 50 μm or less.
The undercoat layer can be formed by using the following dispersion type undercoat layer coating agent. As a result, it is possible to prevent the accumulation of residual charges by appropriately adjusting the resistance value of the undercoat layer, and to increase the thickness of the undercoat layer. In particular, leakage during contact charging can be prevented.

Examples of the dispersion-type undercoat layer coating agent include those obtained by dispersing a conductive filler in an organic polymer as a binder resin. As the conductive filler, metal oxide particles having an average primary particle size of 0.5 μm or less are preferably used. If the average primary particle size is too large, local conductive path formation is likely to occur, current leakage is likely to occur, and as a result, fogging or large current leakage from the charger may occur. The undercoat layer needs to be adjusted to an appropriate resistance value in order to improve leakage resistance. Therefore, the metal oxide particles described above preferably have a powder resistance of about 10 ² Ω · cm to 10 ¹¹ Ω · cm.

Preferred conductive fillers include antimony oxide, indium oxide, tin oxide, zinc oxide, titanium oxide, ITO, copper iodide, metal powder, and the like. Among these, metal oxides such as tin oxide and zinc oxide are preferable.
A preferable average primary particle size of the conductive filler is 0.1 μm or more and 5 μm or less, more preferably 0.2 μm or more and 3 μm or less, and particularly preferably 0.2 μm or more and 2 μm or less. In the present embodiment, the average primary particle size is a value measured by observing the cross section of the film.

  In addition, if the resistance value of the metal oxide particles is lower than the lower limit of the above range, sufficient leakage resistance cannot be obtained, and if the resistance value is higher than the upper limit of this range, the residual potential may be increased. Accordingly, metal oxide particles such as tin oxide, titanium oxide, and zinc oxide having a resistance value within the above range are more preferably used. Moreover, 2 or more types of metal oxide particles can be mixed and used. Furthermore, the resistance of the powder can be controlled by subjecting the metal oxide particles to a surface treatment with a coupling agent. Moreover, these coupling agents can also be used in mixture of 2 or more types.

  A conventionally well-known coupling agent can be selected and used as a coupling agent. Examples of coupling agents that can be used in this embodiment include vinyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane. , Silane coupling agents such as γ-aminopropyltrimethoxysilane, titanium coupling agents and the like. Among these, silane coupling agents such as γ-methacryloxypropyltrimethoxysilane and N-β (aminoethyl) γ-aminopropyltrimethoxysilane are preferable.

For the surface treatment of the metal oxide particles, any known method can be used, but a dry method or a wet method can be used.
In the case of using the dry method, first, the metal oxide particles are dried by heating to remove surface adsorbed water. By removing the surface adsorbed water, the coupling agent can be uniformly adsorbed on the surface of the metal oxide particles. Next, while the metal oxide particles are stirred with a mixer having a large shearing force or the like, the coupling agent dissolved directly or in an organic solvent or water is dropped and sprayed together with dry air or nitrogen gas to be uniformly treated. . When adding or spraying the coupling agent, it is preferably performed at a temperature of 50 ° C. or higher. After adding or spraying the coupling agent, baking is preferably performed at 100 ° C. or higher. Due to the effect of baking, the coupling agent can be cured to cause a solid chemical reaction with the metal oxide particles. Baking can be carried out in an arbitrary range as long as the temperature and the time at which desired electrophotographic characteristics are obtained.

  In the case of using the wet method, the surface adsorbed water of the metal oxide particles is first removed as in the dry method. As a method for removing the surface adsorbed water, in addition to the heat drying similar to the dry method, a method of removing with stirring and heating in a solvent used for the surface treatment, a method of removing by azeotropy with the solvent, and the like can be performed. Next, the metal oxide particles are dispersed in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., added with a coupling agent solution, stirred or dispersed, and then uniformly removed by removing the solvent. Is done. After removing the solvent, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained.

It is essential that the amount of the surface treatment agent with respect to the metal oxide particles is an amount capable of obtaining desired electrophotographic characteristics. The electrophotographic characteristics are affected by the amount of the surface treatment agent attached to the metal oxide particles after the surface treatment. In the case of a silane coupling agent, the amount of adhesion is determined from the Si intensity (derived from the silane coupling agent) measured by fluorescent X-ray analysis and the main metal element strength of the metal oxide used. The Si intensity measured by this fluorescent X-ray analysis is preferably in the range of 1.0 × 10 ⁻⁵ times or more and 1.0 × 10 ⁻³ times or less of the main metal element strength of the metal oxide used. If it falls below this range, image quality defects such as fog are likely to occur, and if it exceeds this range, density reduction due to an increase in residual potential may easily occur.

Examples of the binder resin contained in the dispersion type undercoat layer coating agent include acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Known polymer resin compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, In addition, a charge transporting resin having a charge transporting group, a conductive resin such as polyaniline, and the like can be given.
Among them, a resin insoluble in the coating solvent for the layer formed on the undercoat layer is preferably used, and in particular, a phenol resin, a phenol-formaldehyde resin, a melamine resin, a urethane resin, an epoxy resin, and the like are preferably used.
The ratio (mass basis) between the metal oxide particles and the binder resin in the dispersion-type undercoat layer-forming coating liquid (that is, in the undercoat layer) is preferably 10: 100 to 100: 10, and 20: 100 to 100: 20 is more preferable, and 30: 100 to 100: 30 is particularly preferable.

In addition, it is preferable that the above-described undercoat layer forming coating solution contains at least one electron accepting substance. Specific examples of the electron accepting substance include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-di Examples thereof include nitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, fluorenone-based, quinone-based, and benzene derivatives having an electron-withdrawing substituent such as Cl, CN, NO ₂ are more preferably used. As a result, the photosensitivity in the organic photosensitive layer can be improved and the residual potential can be reduced, and the deterioration of the photosensitivity when repeatedly used can be reduced. The undercoat layer includes a photoconductor containing an electron-accepting substance. The density unevenness of the toner image formed by the image forming apparatus can be prevented.
The content of the electron accepting substance is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less with respect to the metal oxide.

Examples of the method for dispersing the metal oxide particles surface-treated by the above-described method in the binder resin include a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, and a roll mill. And a method using a medialess disperser such as a high-pressure homogenizer. Further, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which the fine liquid is penetrated and dispersed in a high pressure state.
Moreover, as a solvent used for the undercoat layer forming coating solution for forming the undercoat layer, known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, methanol, ethanol, n-propanol, Aliphatic alcohol solvents such as iso-propanol and n-butanol, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, tetrahydrofuran, dioxane and ethylene Examples thereof include cyclic or linear ether solvents such as glycol and diethyl ether, and ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate. These solvents can be used alone or in admixture of two or more. As a solvent that can be used when two or more solvents are mixed, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  The undercoat layer is formed by first preparing an undercoat layer forming coating solution prepared by dispersing and mixing an undercoat layer coating agent and a solvent, and applying the prepared undercoat layer to the surface of the conductive substrate. As a coating method for the coating solution for forming the undercoat layer, it is possible to use usual methods such as a dip coating method, a ring coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method. it can. In the case of forming the undercoat layer, the film thickness is formed in the range of 5 μm to 50 μm. By setting the film thickness of the undercoat layer within such a film thickness range, it is possible to prevent an increase in potential due to desensitization and repetition without excessively strengthening the electrical barrier.

  By forming the undercoat layer on the conductive substrate in this way, it is possible to improve wettability when applying and forming a layer formed on the undercoat layer, and as an electrical blocking layer. The function of can be sufficiently fulfilled.

The surface roughness of the undercoat layer formed as described above is 1 / (4n) times the exposure laser wavelength λ used (where n is the refractive index of the layer provided on the outer peripheral side of the undercoat layer) to It is possible to adjust to have a roughness within a range of about 1 time. The surface roughness is adjusted by adding resin particles to the coating solution for forming the undercoat layer. As a result, when a photoreceptor prepared by adjusting the surface roughness of the undercoat layer is used in an image forming apparatus, an interference fringe image caused by a laser light source can be more sufficiently prevented.
As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like can be used. In addition, the surface of the undercoat layer can be polished to adjust the surface roughness. As a polishing method, buffing, sand blasting, wet honing, grinding, or the like can be used. In the photosensitive member used for the positively charged image forming apparatus, the laser incident light is absorbed in the vicinity of the extreme surface of the photosensitive member and further scattered in the organic photosensitive layer, so that the surface roughness of the undercoat layer is adjusted. Is not strongly required.

-Organic photosensitive layer: Charge transport layer-
Next, the organic photosensitive layer will be described below in this order, divided into a charge transport layer and a charge generation layer.
Examples of the charge transport material used for the charge transport layer include those shown below. That is, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]- Pyrazoline derivatives such as 3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (p-methyl) phenylamine, N, N-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, dibenzylaniline, 9,9-dimethyl-N, N-di (p-tolyl) fluorenon-2-amine, N, N′-diphenyl-N, N Aromatic tertiary diamino compounds such as' -bis (3-methylphenyl)-[1,1-biphenyl] -4,4'-diamine, 3- (4'dimethylaminophenyl) 1,5,6-di- (4'-methoxyphenyl) -1,2,4-triazine, 1,2,4-triazine derivatives, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenyl Aminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, 1-pyrenediphenylhydrazone, 9-ethyl-3-[(2methyl-1-indolinylimino) methyl Carbazole, 4- (2-methyl-1-indolinyliminomethyl) triphenylamine, 9-methyl-3-carbazole diphenylhydrazone, 1,1-di- (4,4′-methoxyphenyl) acrylaldehyde diphenylhydrazone , Β, β-bis (methoxyphenyl) vinyldiphenyl Hydrazone derivatives such as razone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) -benzofuran, p- (2,2-diphenyl) Hole transport materials such as α-stilbene derivatives such as vinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole and derivatives thereof are used. Or the polymer etc. which have the group which consists of the said compound in a principal chain or a side chain are mentioned. These charge transport materials can be used alone or in combination of two or more.

  Any binder resin can be used for the charge transport layer, but the binder resin is preferably compatible with the charge transport material and has an appropriate strength.

  Examples of this binder resin include various polycarbonate resins and copolymers thereof, such as bisphenol A, bisphenol Z, bisphenol C, and bisphenol TP, polyarylate resins and copolymers thereof, polyester resins, methacrylic resins, acrylic resins, Polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, silicone Resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-acrylic copolymer resin, ethylene-alkyd resin, poly-N-vinylcarbazole resin, polyvinyl butyral resin, polyphenylene ether resin, etc. And the like. These resins can be used alone or as a mixture of two or more.

  The molecular weight of the binder resin used in the charge transporting layer is selected depending on the film thickness of the organic photosensitive layer and the film forming conditions such as a solvent, but it is usually preferably within the range of 3000 to 300,000 in terms of viscosity average molecular weight. A range of 10,000 to 200,000 is more preferable.

The charge transport layer and / or the charge generation layer, which will be described later, are used for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, light, or heat generated in the image forming apparatus. Additives such as stabilizers may be included.
Examples of the antioxidant include hindered phenols, hindered amines, paraphenylenediamines, arylalkanes, hydroquinones, spirochromans, spiroidanones or their derivatives, organic sulfur compounds, and organic phosphorus compounds.

  As specific examples of antioxidants, phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′- Di-t-butyl-4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3'-t- Butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3-methyl-6-tert-butyl-phenol), 4,4'-thio- Bis- (3-methyl-6-tert-butylphenol), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxy-phenyl) propionate] -methane, 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5- Methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 3-3 ′, 5′-di-t-butyl-4′- And hydroxyphenyl) stearyl propionate.

  Among hindered amine compounds, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2 , 2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate Condensate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetramethyl- 4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2- n-Butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N— (1,2,2,6,6, -pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate and the like.

Among organic sulfur antioxidants, dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis- (Β-lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like.
Examples of the organophosphorus antioxidant include trisnonylphenyl phosfte, triphenyl phosfeft, tris (2,4-di-t-butylphenyl) -phosfte, and the like.

  Organic sulfur and organophosphorus antioxidants are called secondary antioxidants, and when used in combination with primary antioxidants such as phenols or amines, the antioxidant effect is increased synergistically. Can do.

Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives.
Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2′-di-hydroxy-4-methoxybenzophenone.
As the benzotriazole light stabilizer, 2-(-2′-hydroxy-5′methylphenyl-)-benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″) , 6 ″ -tetra-hydrophthalimido-methyl) -5′-methylphenyl] -benzotriazole, 2-(-2′-hydroxy-3′-t-butyl 5′-methylphenyl-)-5-chlorobenzo Triazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl-)-5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl- ) -Benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) -benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl-)-benzotriazole Etc.
Other light stabilizers include 2,4, di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate, nickel dibutyl-dithiocarbamate, and the like.

The charge transport layer can be formed by applying a solution obtained by dissolving the charge transport material and the binder resin described above in an appropriate solvent and drying the solution. Examples of the solvent used for the preparation of the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene and chlorobenzene, ketones such as acetone and 2-butanone, and halogens such as methylene chloride, chloroform and ethylene chloride. Cyclic aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or a mixed solvent thereof can be used.
In addition, a small amount of silicone oil can be added to the charge transport layer forming coating solution as a leveling agent for improving the smoothness of the coating film to be formed.

  The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 by mass ratio. The thickness of the charge transport layer is generally preferably in the range of 5 μm to 50 μm, more preferably in the range of 10 μm to 40 μm, and still more preferably in the range of 10 μm to 30 μm.

  The coating solution for forming the charge transport layer can be applied by dip coating, ring coating, spray coating, bead coating, blade coating, roller coating, knife coating, curtain coating, depending on the shape and application of the photoreceptor. It can be performed using a coating method such as a coating method. The drying is preferably performed by heating after touch-and-drying at room temperature. The heat drying is desirably performed in a temperature range of 30 ° C. or higher and 200 ° C. or lower for a time in the range of 5 minutes to 2 hours.

-Organic photosensitive layer: Charge generation layer-
The charge generation layer is formed by depositing a charge generation material by a vacuum deposition method or by applying a solution containing an organic solvent and a binder resin.

Examples of charge generation materials include amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, and other selenium compounds; inorganic photoconductors such as selenium alloy, zinc oxide, and titanium oxide; Sensitized, various phthalocyanine compounds such as metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, gallium phthalocyanine; Various organic pigments such as salts; or dyes are used.
In addition, these organic pigments generally have several types of crystals. In particular, phthalocyanine compounds have various crystal types including α type and β type. Any of these crystal forms can be used as long as it is a pigment capable of obtaining characteristics.

  Of the charge generation materials described above, phthalocyanine compounds are preferred. In this case, when the organic photosensitive layer is irradiated with light, the phthalocyanine compound contained in the organic photosensitive layer absorbs photons and generates carriers. At this time, since the phthalocyanine compound has a high quantum efficiency, the absorbed photons can be efficiently absorbed to generate carriers.

Furthermore, among the phthalocyanine compounds, phthalocyanines shown in the following (1) to (3) are more preferable. That is,
(1) At least 7.6 °, 10.0 °, 25.2 °, 28.0 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material Crystalline hydroxygallium phthalocyanine having a diffraction peak at the position.
(2) At least 7.3 °, 16.5 °, 25.4 °, 28.1 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material Crystalline chlorogallium phthalocyanine having a diffraction peak at the position.
(3) Diffraction peaks at positions of at least 9.5 °, 24.2 °, and 27.3 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material. A crystalline form of titanyl phthalocyanine.

  Since these phthalocyanine compounds have not only high photosensitivity but also high stability of photosensitivity, a photoreceptor having an organic photosensitive layer containing these phthalocyanine compounds requires high-speed image formation and reproducibility. It is suitable as a photoreceptor for a color image forming apparatus.

  Note that the peak intensity and position may slightly deviate from these values depending on the crystal shape and measurement method. However, if the X-ray diffraction patterns are basically the same, the same crystal type is assumed. I can judge.

  Examples of the binder resin used for the charge generation layer include the following. That is, polycarbonate resin such as bisphenol A type or bisphenol Z type and copolymers thereof, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin Vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole and the like.

  These binder resins can be used alone or in admixture of two or more. The mixing ratio of the charge generation material and the binder resin (charge generation material: binder resin) is preferably in the range of 10: 1 to 1:10 by mass ratio. The thickness of the charge generation layer is generally preferably in the range of 0.01 μm to 5 μm, and more preferably in the range of 0.05 μm to 2.0 μm.

The charge generation layer may contain at least one electron accepting substance for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron accepting material used in the charge generation layer include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, and o-dinitrobenzene. M-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, peak phosphoric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

As a method for dispersing the charge generating material in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a dyno mill, a sand mill, and a colloid mill can be used.
Known organic solvents as coating solution solvents for forming the charge generation layer, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, fats such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol Aromatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether And ether solvents such as methyl ether, methyl acetate, ethyl acetate, and n-butyl acetate.

  These solvents can be used alone or in combination of two or more. When two or more kinds of solvents are mixed and used, any solvent that can dissolve the binder resin as the mixed solvent can be used. However, when the organic photosensitive layer has a layer structure in which the charge transport layer and the charge generation layer are formed in this order from the conductive substrate side, the charge is applied by using a coating method that easily dissolves the lower layer, such as dip coating. When forming the generation layer, it is desirable to use a solvent that does not dissolve the lower layer such as the charge transport layer. In addition, when the charge generation layer is formed by using a spray coating method or a ring coating method with a relatively low erosion property of the lower layer, the selection range of the solvent can be expanded.

-Intermediate layer-
For example, when charging the surface of the photoconductor with a charger, it is necessary to prevent the charged potential from being obtained from the surface of the photoconductor to the conductive substrate of the photoconductor as the counter electrode. Accordingly, an intermediate layer can be formed as a charge injection blocking layer between the surface layer and the charge generation layer.
As the material for the charge injection blocking layer, general-purpose resins such as the silane coupling agents, titanium coupling agents, organic zirconium compounds, organic titanium compounds, other organic metal compounds, polyesters, and polyvinyl butyral listed above can be used. The film thickness of the charge injection blocking layer is set in the range of about 0.001 μm or more and 5 μm or less in consideration of film forming properties and carrier blocking properties.

(Manufacturing method of surface layer)
Next, the manufacturing method of the surface layer concerning this embodiment is demonstrated. For the surface layer according to the present embodiment, a known vapor deposition method such as a plasma CVD (Chemical Vapor Deposition) method, a metal organic vapor phase epitaxy method, a molecular beam epitaxy method, vapor deposition, or sputtering can be used. It is preferable to use a growth method.
In this case, the substance containing nitrogen or the substance containing oxygen is made an active species by activating means for activating the substance containing nitrogen or the substance containing oxygen to an energy state or an excited state necessary for the reaction, and the active species It is preferable to form the surface layer according to the present embodiment on the substrate by reacting with an organometallic compound containing a group 13 element that is not activated.
Thereby, when the base material contains an organic material, for example, even when it is an organic photoreceptor, the above-described characteristics as the surface layer of the photoreceptor are obtained without causing thermal damage to the conductive substrate or the organic photosensitive layer. A surface layer can be formed. When forming the surface layer, the surface of the base material may be previously cleaned with plasma.
Activate the organometallic compound containing a group 13 element and react it with a species containing nitrogen or a substance containing oxygen activated to an energy state or excited state necessary for the reaction. A layer may be formed.

Note that the surface layer is usually formed by placing a substrate on each of a substance containing nitrogen, a substance containing oxygen, a gas composed of an organometallic compound containing a group 13 element, or a gas obtained by vaporizing them. It is performed while exhausting the gas that has finished the reaction from the reaction chamber while supplying it into the reaction chamber (film formation chamber). From such a viewpoint, it is preferable to introduce an organometallic compound containing a group 13 element downstream of an activating means for activating a substance containing nitrogen or a substance containing oxygen. Alternatively, when the substrate is rotated, the group 13 element may be spatially separated on the plane with the upstream of the rotation and the activation means downstream of the rotation. A partition may be used as the separating means, or may be installed with a spatial distance.
As a result, the activated nitrogen-containing substance or oxygen-containing substance is joined upstream or downstream of the position where the organometallic compound containing the group 13 element is introduced. And an activated nitrogen-containing substance or oxygen-containing substance can be reacted.
In the case of rotating the substrate, in addition to the positional relationship described above, an activating means for activating a substance containing nitrogen or a substance containing oxygen on the upstream side of the rotation from an organometallic compound containing a group 13 element on the downstream side of the rotation. Or a gas obtained by vaporizing them may be supplied.

  Further, the maximum temperature of the substrate surface when the surface layer according to this embodiment is formed on the substrate is preferably 100 ° C. or less, preferably 50 ° C. or less, and the maximum temperature of the substrate surface. The closer to normal temperature, the better. When the temperature exceeds 100 ° C., the base material may be deformed or the physical properties may be deteriorated due to decomposition of an organic material contained in the base material. Also, a large amount of residual stress is generated inside the organic photosensitive layer due to the difference in thermal expansion coefficient during film formation, which causes deterioration of the electrical characteristics of the electrophotographic photoreceptor. Specifically, there are problems such as a decrease in sensitivity, an increase in residual potential due to the generation of space charges inside the organic photosensitive layer, and image quality unevenness due to variations in space charges.

Below, the manufacturing method of a surface layer is demonstrated in detail.
FIG. 3 is a schematic diagram illustrating an example of a film forming apparatus used for forming the surface layer. FIG. 3A is a schematic cross-sectional view when the film forming apparatus is viewed from the side, and FIG. The schematic cross section between A1-A2 of the film-forming apparatus shown is represented. In FIG. 3, 10 is a film forming chamber, 11 is an exhaust port, 12 is a substrate rotating part, 13 is a substrate holder, 14 is a substrate, 15 is a plate electrode, 16 is a gas introduction tube, 17 is a gas nozzle, and 18 is a gas introduction tube. , 19 is a high frequency power supply unit, and 20 is a high frequency power supply unit.

In the film forming apparatus shown in FIG. 3, an exhaust port 11 connected to a vacuum exhaust apparatus (not shown) is provided at one end of the film forming chamber 10, and the side of the film forming chamber 10 where the exhaust port 11 is provided. On the opposite side, a plasma generator comprising a high-frequency power source 20, a high-frequency power supply unit 19 and a plate electrode 15 is provided.
A gas introduction pipe 16 for supplying a second non-film forming gas is connected to the flat plate electrode 15. A gas hole for supplying gas to the substrate is opened on the surface of the plate electrode 15 facing the substrate. The holes may be evenly spaced or distributed unevenly.
A gas nozzle 17 for introducing a first gas is provided in the vicinity of the substrate. A gas introduction pipe 18 for supplying gas is connected to the gas nozzle.
The other end of the gas introduction pipe 18 is connected to a first gas supply source (not shown) provided outside the film forming chamber 10.

A rod-shaped shower nozzle substantially parallel to the discharge surface may be connected to the discharge surface side of the plate electrode 15. The gas introduction pipe 16 is connected to a second gas supply source (not shown) provided outside the film forming chamber 10.
In addition, a substrate rotating unit 12 is provided outside the film forming chamber 10, and the substrate holder 14 is arranged so that the cylindrical substrate 14 faces the plate electrode 15, the gas nozzle 17, and the axial direction of the substrate 14 substantially in parallel. 13, and can be attached to the base rotating unit 12. During film formation, the substrate 14 can be rotated in the circumferential direction by rotating the substrate rotating unit 12. As the substrate 14, a photoconductor previously laminated up to the organic photosensitive layer or a photoconductor laminated up to the intermediate layer on the organic photosensitive layer is used. The direction of rotation may be the direction from the parallel electrode 15 toward the gas nozzle 17 or the opposite direction.

The formation of the surface layer can be performed, for example, as follows. First, when H ₂ gas, He gas, oxygen gas or nitrogen gas is introduced from the gas introduction tube 16 to the plate electrode 15 and a 13.56 MHz radio wave is supplied, plasma is formed between the plate electrode 15 and the substrate. The Here, the gas introduced from the gas introduction pipe 16 through the plate electrode 15 flows through the film forming chamber 10 from the plate electrode 15 side to the exhaust port 11 side.
The plate electrode 15 preferably has an electrode surrounded by an earth shield. Further, a cylindrical electrode in which the base body is concentrically surrounded may be used.
Next, by introducing a trimethylgallium gas diluted with hydrogen as a carrier gas into the film forming chamber 10 through the gas introduction pipe 18 and the gas nozzle 17 located adjacent to the flat plate electrode 15 as the activating means, A non-single crystal film containing gallium and nitrogen or oxygen can be formed on the surface of the substrate 14. The composition is controlled by reducing the amount of nitrogen or oxygen from the case where the film formed of saturated oxygen or saturated nitrogen has a stoichiometric ratio. For example, a film composition with an oxygen amount whose characteristics do not change with an increase in oxygen gas concentration can be used as the stoichiometric ratio of the oxide. Alternatively, the film composition with a nitrogen amount whose characteristics do not change with an increase in nitrogen gas concentration can be used as the stoichiometric ratio of nitride. However, when oxygen or nitrogen gas is introduced in excess of the saturation point, a film having a chemical composition different from that determined by the stoichiometric ratio may be formed.

The formation temperature of the surface layer at the time of film formation is not particularly limited, but in the case of producing a photoreceptor, the temperature of the surface of the substrate 14 at the time of film formation of the surface layer is preferably 100 ° C. or less, more preferably 80 ° C. or less, A temperature of 50 ° C. or lower is particularly preferable. Even if the temperature of the surface of the substrate 14 is 100 ° C. or less at the beginning of film formation, the organic photosensitive layer may be damaged by heat if it becomes higher than 150 ° C. due to the influence of plasma. It is preferable to control the surface temperature of the substrate 14 in consideration.
The temperature of the surface of the substrate 14 may be controlled by heating and / or cooling means (not shown in the figure), or may be left to a natural temperature increase during discharge. When heating the substrate 14, a heater may be installed outside or inside the substrate 14. When the substrate 14 is cooled, a cooling gas or liquid may be circulated inside the substrate 14.
In order to avoid an increase in the temperature of the surface of the substrate 14 due to electric discharge, it is effective to adjust a high-energy gas flow that strikes the surface of the substrate 14. In this case, conditions such as the gas flow rate, discharge output, and pressure are adjusted so as to achieve the required temperature.

As the gas containing a group 13 element, an organic metal compound containing indium or aluminum or a hydride such as diborane may be used instead of trimethylgallium gas, and two or more of these may be mixed.
For example, in the initial stage of forming the surface layer, trimethylindium is introduced into the film forming chamber 10 through the gas introduction tube 16 and the plate electrode 15, thereby forming a film containing nitrogen and indium on the substrate 14. For example, this film can absorb ultraviolet rays that occur when the film is continuously formed and degrade the organic photosensitive layer. For this reason, damage to the organic photosensitive layer due to the generation of ultraviolet rays during film formation can be suppressed.

In addition, a dopant can be added to the surface layer in order to control its conductivity type. As a dopant doping method at the time of film formation, SiH ₃ and SnH ₄ are used for n-type, and biscyclopentadienyl magnesium, dimethyl calcium, dimethyl strontium, dimethyl zinc, diethyl zinc, etc. are used for p-type. Can be used in the gas state. In order to dope the dopant element into the surface layer, a known method such as a thermal diffusion method or an ion implantation method may be employed.
Specifically, a surface layer of any conductivity type such as n-type or p-type is introduced by introducing a gas containing at least one dopant element into the film forming chamber 10 through the gas introduction tube 16 and the plate electrode 15. Can be obtained.

Note that when an organometallic compound containing a hydrogen atom is used as a supply material for a group 13 atom and a surface layer mainly containing a group 13 atom and a nitrogen atom or oxygen is formed, active hydrogen exists in the film forming chamber 10. It is preferable to do. The active hydrogen may be supplied from a hydrogen atom used as a carrier gas or a hydrogen atom contained in an organometallic compound.
For example, in the film forming apparatus shown in FIG. 3, when hydrogen gas and nitrogen gas or oxygen gas are introduced into the film forming apparatus from different positions, the hydrogen gas activation state and the nitrogen gas or oxygen gas A plurality of plasma generators may be provided so that the activated state can be independently controlled. On the other hand, in terms of simplification of the apparatus, as a supply material for hydrogen and nitrogen gas or oxygen gas, a gas containing simultaneously nitrogen atoms and hydrogen atoms such as NH ₃ is used, or oxygen and hydrogen are simultaneously contained. It is preferable to activate by plasma using H ₂ O gas or a gas in which oxygen gas and hydrogen gas are mixed.
Further, when a rare gas such as helium or hydrogen is used in combination as a carrier gas, the etching effect of the film grown on the surface of the substrate 14 with a rare gas such as helium and hydrogen can be used even at a low temperature of 100 ° C. or less. An amorphous group 13 element with less hydrogen and nitrogen or oxygen can be formed.

By the above-described method, activated hydrogen, nitrogen or oxygen, a rare gas, and a group 13 atom exist in the vicinity of the surface of the substrate 14, and the activated rare gas and hydrogen constitute an organometallic compound. It has the effect of desorbing hydrogen of hydrocarbon groups such as methyl and ethyl groups as molecules. Therefore, a surface layer made of a hard film having a low hydrogen content and forming a three-dimensional bond of nitrogen or oxygen and a group 13 element is formed on the surface of the substrate 14 at a low temperature.
Such a hard film is different from sp ² -bonding carbon atoms contained in an amorphous carbon film, and is transparent because Ga and N form sp ³ bonds like carbon atoms constituting diamond. Become. Furthermore, the film is transparent and hard, and the film surface is water repellent and at the same time has low friction. In the case of Ga and O, O has a large proportion of O in the octahedral structure and is a hard and chemically stable film. The same applies to Al and In.

The plasma generating means of the film forming apparatus shown in FIG. 3 uses a high-frequency oscillation device, but is not limited to this. For example, a microwave oscillation device, an electrocyclotron resonance method, or a helicon plasma is used. You may use the apparatus of a system. In the case of a high-frequency oscillation device, it may be inductive or capacitive.
Furthermore, two or more of these devices may be used in combination, or two or more of the same types of devices may be used. In order to prevent the temperature of the substrate 14 from rising due to plasma irradiation, a high-frequency oscillation device is preferable, but a device for preventing heat irradiation may be provided.
A plurality of electrodes may be provided around one substrate, or a plurality of gas nozzles may be provided. Further, an electrode and a gas nozzle may be provided as a pair.

When two or more types of different plasma generators (plasma generating means) are used, it is necessary to be able to generate discharges simultaneously at the same pressure. In addition, a pressure difference may be provided between the discharge region and the film formation region (the portion where the base is installed). These apparatuses may be arranged in series with respect to the gas flow formed in the film forming apparatus from the part where the gas is introduced to the part where the gas is discharged. You may arrange | position so that it may oppose.
In addition, when two different types of plasma generators are used under the same pressure, for example, when using a microwave oscillator and a high-frequency oscillator, the excitation energy of the excited species can be greatly changed, and the film quality can be controlled. It is valid. Moreover, you may perform discharge near atmospheric pressure.
When discharging near atmospheric pressure, it is desirable to use He as a carrier gas.

  In addition to the above-described methods, the surface metal layer can be formed by a normal metal organic vapor phase epitaxy method or molecular beam epitaxy method. Use of oxygen and active nitrogen is effective for lowering the temperature.

<Image forming apparatus>
Next, the image forming apparatus of this embodiment will be described.
The image forming apparatus of this embodiment includes an electrophotographic photoreceptor according to the above embodiment, a charging unit that charges the surface of the electrophotographic photoreceptor, and an electrostatic latent image on the charged surface of the electrophotographic photoreceptor. An electrostatic latent image forming means for forming; an image forming means for developing a latent electrostatic image formed on the surface of the electrophotographic photosensitive member using a developer containing at least toner; and forming the toner image; The image forming apparatus includes a transfer unit that transfers the toner image formed on the surface of the photographic photosensitive member to the surface of the transfer target, and a fixing unit that fixes the toner image transferred to the surface of the transfer target.
The image forming apparatus according to the present exemplary embodiment includes a cleaning unit that removes residual toner on the surface of the electrophotographic photosensitive member after transfer, as necessary, and the surface of the electrophotographic photosensitive member together with the toner when forming a toner image. You may further have the carrier collection means which collects the transferred improper carrier by magnetic force.

In this image forming apparatus, for example, the portion including the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is detachably attached to the main body of the image forming apparatus.
Hereinafter, although an example of the image forming apparatus of this embodiment is shown, it is not necessarily limited to this. The main parts shown in the figure will be described, and the description of the other parts will be omitted.

  FIG. 4 is a schematic configuration diagram showing a four-tandem full-color image forming apparatus. The image forming apparatus shown in FIG. 4 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K are provided. These image forming units (hereinafter simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed at a predetermined distance in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the main body of the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. It is designed to travel in the direction toward 10K. The support roller 24 is biased in a direction away from the drive roller 22 by a spring or the like (not shown), and a predetermined tension is applied to the intermediate transfer belt 20 wound around both. Further, an intermediate transfer member cleaning device 30 is provided on the side surface of the photosensitive member of the intermediate transfer belt 20 so as to face the driving roller 22.
Further, each of the developing devices (image forming means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and toner contained in the toner cartridges 8Y, 8M, 8C, and 8K. Black toner of four colors can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. Note that the second to fourth units are denoted by reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the same parts as the first unit 10Y. Description of 10M, 10C, 10K is omitted.

The first unit 10Y has an electrophotographic photoreceptor (photoconductor) 1Y. Around the photoconductor 1Y, a charging roller 2Y (charging means) that is a contact type charger that charges the surface of the photoconductor 1Y to a predetermined potential, and the surface of the charged photoconductor 1Y is color-separated into image signals. An exposure device 3 (electrostatic latent image forming means) for forming an electrostatic latent image by exposure with a laser beam 3Y based thereon, and a developing device (image for supplying the electrostatic latent image with charged toner and developing the electrostatic latent image) Forming means) 4Y, a primary transfer roller 5Y (primary transfer means) for transferring the toner image onto the intermediate transfer belt 20, and a cleaning blade (cleaning means) for removing the toner remaining on the surface of the photoreceptor 1Y after the primary transfer. ) 6Y is provided.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
A laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the organic photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic latent image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic latent image is formed as a so-called negative latent image on the surface of the photoreceptor 1Y by electric charges.
The electrostatic latent image formed on the photoreceptor 1Y in this manner is conveyed to a predetermined development position according to the rotation of the photoreceptor 1Y. At this development position, the electrostatic latent image on the photoreceptor 1Y is converted into a visible image (toner image) by the developing device 4Y.

  A developer (two-component developer) containing yellow toner and a carrier is accommodated in the developing device 4Y. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, yellow toner adheres electrostatically to the latent image portion on the surface of the photoreceptor 1Y, and the electrostatic latent image is developed with the yellow toner. Is done. The photoconductor 1Y on which the yellow toner image is formed continuously rotates at a predetermined speed, and the toner image developed on the photoconductor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer position, a predetermined primary transfer bias is applied to the primary transfer roller 5Y, and the electrostatic force directed from the photoreceptor 1Y to the primary transfer roller 5Y generates toner. Acting on the image, the toner image on the photoreceptor 1 </ b> Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner, and is controlled to about +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoreceptor 1Y is removed by the cleaning blade 6Y and collected.

  Similarly, a magenta toner image is sequentially formed in the second unit 10M, a cyan toner image is formed in the third unit 10C, and a black toner image is formed in the fourth unit 10K. An image is formed.

  The intermediate transfer belt 20 onto which the four color toner images have been transferred is transferred to the intermediate transfer belt 20, a support roller 24 in contact with the inner surface of the intermediate transfer belt 20, and a secondary transfer roller (located on the image holding surface side of the intermediate transfer belt 20. Secondary transfer means) 26 to a secondary transfer portion. On the other hand, the recording paper P (transfer object) is fed at a predetermined timing to a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via a supply mechanism, and a predetermined secondary transfer bias is supported. Applied to the roller 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and the intermediate transfer belt 20 The toner image is transferred onto the recording paper P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

Thereafter, the recording paper P is fed into a fixing device (fixing means) 28, where the toner image is heated, and the color-superposed toner image is melted and fixed on the recording paper P. The recording paper P on which the color image has been fixed is unloaded to the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the toner image onto the recording paper P via the intermediate transfer belt 20, but the present invention is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure that is transferred to a recording sheet.

  In the image forming apparatus of the present embodiment, the charging roller 2 that is a contact-type charger is used as the charging unit. However, the contact using a brush-like, film-like, or pin-electrode-like conductive or semiconductive charging member is used. A type charger may be used, or a non-contact type charger such as a scorotron charger using a corona discharge or a corotron charger may be used. The contact charger can suppress the amount of ozone generated when charging the photoconductor as compared with the non-contact charger, but the life of the photoconductor may be shortened by a minute discharge. However, since the electrophotographic photoreceptor of this embodiment includes a predetermined surface layer, the life of the photoreceptor can be extended even if a contact charger is used.

A known rubber material can be used as the material of the cleaning blade 6. For example, urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber, or the like can be used. Among them, urethane rubber (polyurethane elastic body) is preferably used because of its excellent wear resistance.
As the polyurethane elastic body, a polyurethane generally synthesized through an addition reaction between an isocyanate and a polyol and various hydrogen-containing compounds is used. As a polyol component, a polyether-based polyol such as polypropylene glycol or polytetramethylene glycol, Polyester polyols such as adipate polyols, polycaprolactam polyols, polycarbonate polyols are used, and polyisocyanate components include aromatics such as tolylene diisocyanate, 4,4'diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate, etc. Polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclo It is manufactured by preparing a urethane prepolymer using an aliphatic polyisocyanate such as xylmethane diisocyanate, adding a curing agent to the urethane prepolymer, pouring it into a predetermined mold, crosslinking and curing, and then aging at room temperature. ing. As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination.

The physical properties of the cleaning blade 6, the hardness (JIS A scale) 50 to 90, Young's modulus (kg / cm ²⁾ 40~90,100% modulus (kg / cm ²⁾ is 20～65,300% modulus ( kg / cm ² ) of 70 to 150, tensile strength (kg / cm ² ) of 240 to 500, elongation (%) of 290 to 500, rebound resilience (%) of 30 to 70, tear strength (kg / cm ² ) 25 to 75 and permanent elongation (%) of 4.0 or less are preferable.

The pressure contact force of the cleaning blade 6 to the photoreceptor 1 is preferably 5 gf / cm or more and 25 gf / cm or less, and more preferably 7 gf / cm or more and 23 gf / cm or less. By setting the pressing force of the cleaning blade 6 to the photosensitive member 1 to 5 gf / cm or more and 25 gf / cm or less, deterioration of the photosensitive member due to wear can be prevented, so that the life of the photosensitive member can be extended. Since the surface of the electrophotographic photoreceptor according to the exemplary embodiment is smooth and slidable, the pressure of the cleaning blade can be reduced. For this reason, it can be used even if the pressing force is set to be lighter than before. The pressing force of the conventional cleaning blade against the photoreceptor is usually about 30 gf / cm.
In the conventional surface layer premised on wear, scratches and dents such as dents disappear due to wear and thus do not become a big problem. In contrast, organic photoreceptors with low wear and a thin hard surface layer have the greatest problem of scratches and dents on the surface. For this reason, blade cleaning does not cause scratches due to foreign matters. There is a need. The electrophotographic photosensitive member according to this embodiment has a low surface friction, does not cause toner filming and discharge product adhesion, and is unlikely to cause poor cleaning. Therefore, the pressing force of the cleaning blade can be reduced. As a result, long-term stable image quality can be provided.

  In the image forming apparatus according to this embodiment, the cleaning unit may further include an electrostatic brush disposed on the upstream side of the cleaning blade. By disposing the electrostatic brush on the upstream side of the cleaning blade, most of the residual toner can be removed by the electrostatic brush before the residual toner is removed by the cleaning blade. Therefore, it is possible to reduce the amount of the illegal carrier transferred to the surface of the photoconductor included in the residual toner and entering the contact portion between the photoconductor and the cleaning blade. As a result, the occurrence of scratches on the surface of the photoreceptor can be suppressed.

  As the electrostatic brush, a fibrous substance made of a resin containing a conductive filler such as carbon black or a metal oxide, or a fibrous substance having a surface coated with the conductive filler can be used. However, it is not limited to these.

  In the image forming apparatus according to the present embodiment, the illegal carrier is disposed on the downstream side of the developing device 4 and the upstream side of the primary transfer roller 5 and is transferred to the surface of the photoreceptor 1 together with the toner when forming the toner image. There may be further provided a carrier collecting means for collecting the gas by a magnetic force.

  Theoretically, the carrier does not transfer to the photoconductor 1 during development, but actually, the carrier may transfer to the surface of the photoconductor 1 together with the toner (hereinafter, the transferred carrier is referred to as an illegal carrier). Called).

  This illegal carrier causes a bad influence on the image quality such as an image blank, and also causes a scratch on the surface of the photoreceptor 1 in the primary transfer portion. Therefore, it is necessary to collect illegal carriers before transfer.

  Therefore, a carrier collecting unit may be disposed between the developing device 4 and the primary transfer roller 5 on the peripheral surface of the photoreceptor 1.

  The carrier collecting means can be composed of a magnet catch-up roll disposed to face the peripheral surface of the photoreceptor 1 and a roll housing that covers the magnet catch-up roll.

  The magnet catch-up roll includes a roll body having magnetic force and a conductive sleeve disposed so as to cover the peripheral surface of the roll body. As a result, the conductive sleeve is in direct contact with the photoreceptor 1.

  The magnet catch-up roll rotates following the rotation of the photosensitive member 1 and has a function of collecting illegal carriers by a magnetic field force.

  Thereby, the illegal carrier discharged from the developing device 4 is collected before reaching the primary transfer roller 5 and can be appropriately transferred.

  When the surface layer of the electrophotographic photoreceptor according to the present embodiment contains hydrogen, the surface energy on the outermost surface of the surface layer is reduced as described above. Therefore, the amount of toner remaining on the photoreceptor surface is suppressed. Therefore, the image forming apparatus according to the present embodiment can be configured as an image forming apparatus that does not include a cleaning unit.

<Process cartridge>
FIG. 5 is a schematic configuration diagram showing a preferred example of the process cartridge of the present embodiment. In the process cartridge 200, the charging device 108, the developing device 111, the cleaning unit 113, the opening 118 for exposure, and the opening 117 for discharging exposure are combined with the photosensitive member 107 by using the mounting rail 116, and It is an integrated one.
The process cartridge 200 is detachable from an image forming apparatus main body including a transfer device 112, a fixing device 115, and other components (not shown). It forms a forming apparatus. Reference numeral 300 denotes a recording sheet.

The process cartridge shown in FIG. 5 includes a photosensitive member 107, a charging device 108, a developing device 111, a cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. Can be selectively combined.
The process cartridge according to this embodiment forms an electrostatic latent image on the surface of the electrophotographic photosensitive member, the charging means for charging the surface of the electrophotographic photosensitive member, and the charged surface of the electrophotographic photosensitive member. An electrostatic latent image forming means for developing, an image forming means for forming a toner image by developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing at least toner, and forming the toner image A carrier collecting means for collecting illegal carriers transferred to the surface of the electrophotographic photosensitive member together with the toner by magnetic force, and a transfer for transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the transfer target. Selected from the group consisting of: fixing means for fixing the toner image transferred to the surface of the transfer member; and cleaning means for removing residual toner on the surface of the electrophotographic photosensitive member after transfer. Having at least a one, the integral is only to be detachable from the image forming apparatus main body.

-Toner-
The toner used in the exemplary embodiment is not particularly limited as long as it is a known toner.
The toner shape factor SF1 is preferably 100 or more and 140 or less, and more preferably 110 or more and 135 or less. If the shape factor SF1 is greater than 140, it may be difficult to obtain good transferability and the like, and it may be difficult to improve the image quality of the obtained image.
The shape factor SF1 is a value defined by the following equation.
SF1 = (ML ² / A) × (π / 4) × 100
In the formula, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.

The shape factor SF1 can be measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT).
First, an optical microscope image of the toner spread on the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and the projected area (A) are measured for 50 or more toners. Next, for each toner, the maximum length squared / (4 × projected area / π), that is, ML ² / (4A / π), was calculated, and an average value thereof was obtained as the shape factor SF1.

On the other hand, the toner used in the exemplary embodiment preferably has a volume average particle diameter of 2 to 8 μm in order to obtain high image quality.
The toner used in this embodiment contains a binder resin and a colorant, and contains a release agent and other additives as necessary. As the binder resin, a binder resin conventionally used for toner can be used and is not particularly limited.

Specific examples of the binder resin include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, and the like. Acrylic monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc .; acrylic acid, methacrylic acid, sodium styrenesulfonate, etc. Ethylenically unsaturated acid monomers; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Ren, propylene, homopolymer consisting of a monomer such as olefins such as butadiene, copolymers combinations thereof monomers of two or more, or the like mixtures thereof.
Furthermore, mixtures of these homopolymers, copolymers or mixtures with non-vinyl condensation resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, non-vinyl condensation resins Examples thereof include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence.

  A conventionally known colorant can be used as the colorant, and is not particularly limited. For example, carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, brilliantamine 6B, dupont oil red, pyrazolone Various pigments such as red, resol red, rhodamine B lake, lake red C, rose bengal, aniline blue, ultramarine blue, chalcoil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalelate, acridine series, Xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine Various dyes such as thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole can be used singly or in combination. .

  Release agents that can be added to the toner used in the exemplary embodiment as necessary include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones, oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide. Fatty acid amides such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, fisher Examples thereof include mineral-based or petroleum-based waxes such as Tropsch wax, and modified products thereof. At least one of these may be contained in the toner particles.

  In addition to the above components, the toner can contain various components in order to control various characteristics. For example, when used as a magnetic toner, a magnetic powder (for example, ferrite or magnetite), a metal such as reduced iron, cobalt, nickel, or manganese, an alloy, or a compound containing these metals may be included. Furthermore, if necessary, a charge control agent that is usually used, such as a quaternary ammonium salt, a nigrosine compound, or a triphenylmethane pigment, may be selected and contained.

  Furthermore, known external additives such as abrasives, lubricants, and transfer aids can be externally added to the toner as necessary.

  Lubricating particles can also be used as the lubricant externally added to the toner. These lubricating particles have a fatty acid metal salt such as zinc stearate, solid lubricants such as graphite, molybdenum disulfide, talc and fatty acids, low molecular weight polyolefins such as polypropylene, polyethylene and polybutene, and a softening point upon heating. Aliphatic amides such as silicones, oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide, plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, beeswax animals Mineral wax, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax and other minerals, petroleum wax, and modified products thereof can be used, and these listed materials may be used alone or in combination. Among these, in this embodiment, it is preferable to use zinc stearate.

  The volume average primary particle size of the slippery particles is preferably in the range of 0.1 μm to 10 μm, and more preferably in the range of 0.2 μm to 8 μm. In addition, by pulverizing the slipping particles, the particle size distribution may be reduced and the particle sizes may be made uniform. The addition amount of the lubricious particles is preferably in the range of 0.05 to 2.0% by mass, preferably 0.1 to 1.5% by mass with respect to the toner particles and all additives externally added to the surface. Within the range is more preferable.

The method for producing the toner used in the present embodiment is not particularly limited. For example, a normal pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, A toner production method by a known polymerization method such as an emulsion polymerization aggregation method can be used. Among these, a polymerization method that can easily produce a toner having a shape factor SF1 of 100 to 140 is preferable.
In addition to the above-described abrasives and lubricants, the toner used in the exemplary embodiment may appropriately include various external additives such as inorganic particles such as silica and titania having an average particle diameter of about 10 to 300 nm. Can be added externally.

-Career-
The carrier that can be used for the two-component developer is not particularly limited, and a known carrier can be used. In particular, a magnetic metal such as iron oxide, nickel, and cobalt, and a magnetic oxide such as ferrite and magnetite can be used. It is preferable to use a resin-coated carrier in which a core material (core) is coated with a resin.

The resin-coated carrier is charged by being stirred together with the toner and the external additive in the developing device. Since the surface of the resin-coated carrier is covered with the resin, the damage due to the mechanical rubbing force is small, and the resin-coated carrier is hardly crushed to generate fine powder.
In the conventional carrier in which the generation of fine powder or the like has been remarkable, the fine powder or the like may be pressed against the photoconductor in the transfer process, and the photoconductor may be damaged or pierced. Since it rushes into the cleaning blade over a long period of time, chipping of the blade tip has been a problem. The toner leaks from the portion where the blade tip is missing, and the toner enters an image in a later process, resulting in an image quality defect. However, in the resin-coated carrier, generation of fine powder and the like is extremely small, and these problems are significantly improved.

As a resin used for the resin-coated carrier, a known resin can be used as long as it is used as a resin layer material for a carrier, and two or more kinds of resins may be blended and used. The resin constituting the resin layer is roughly classified into a charge imparting resin for imparting chargeability to the toner and a resin having a low surface energy used for preventing the toner component from being transferred to the carrier.
Here, examples of the charge imparting resin for imparting negative chargeability to the toner include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Furthermore, polystyrene resins such as polyvinyl and polyvinylidene resins, acrylic resins, polymethyl methacrylate resins, styrene acrylic copolymer resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, ethyl cellulose resins And the like.
Examples of the charge imparting resin for imparting positive chargeability to the toner include polystyrene resins, halogenated olefin resins such as polyvinyl chloride, polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, and polycarbonate resins. Can be mentioned.
Examples of the resin having a low surface energy used for preventing the transfer of the toner component to the carrier include polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, fluororesin. Fluoroterpolymers such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, And silicone resin.

  Moreover, you may add electroconductive particle to a resin layer for the purpose of resistance adjustment. Examples of the conductive particles include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. These conductive powders preferably have an average particle size of 1 μm or less. Furthermore, a plurality of conductive resins and the like can be used in combination as necessary.

The resin layer may contain resin particles for the purpose of charge control. As the resin constituting the resin particles, a thermoplastic resin or a thermosetting resin can be used.
In the case of thermoplastic resins, polyolefin resins, such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins, such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl Ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of an organosiloxane bond or a modified product thereof; fluororesin such as polytetrafluoroethylene, polyvinyl fluoride, polyfluoride And vinylidene chloride, polychlorotrifluoroethylene; polyester; polycarbonate and the like.

  Examples of thermosetting resins include phenol resins; amino resins such as urea-formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins; epoxy resins and the like.

  Examples of the core material of the resin-coated carrier include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite. The volume average particle diameter of the core material is generally 10 μm or more and 500 μm or less, preferably 30 μm or more and 100 μm or less.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<< Electrophotographic photoreceptor >>
Example 1
First, an organic photoreceptor was produced by laminating an undercoat layer, a charge generation layer, and a charge transport layer in this order on an Al substrate by the procedure described below.

-Formation of undercoat layer-
100 parts by mass of zinc oxide having an average primary particle size of 70 nm was mixed with 500 parts by mass of tetrahydrafuran, 1.25 parts by mass of a silane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 2 hours. . Thereafter, baking was performed to obtain a silane coupling agent surface-treated zinc oxide pigment.
60 parts by mass of the surface-treated zinc oxide, 0.6 parts by mass of alizarin, 13.5 parts by mass of a hardener-blocked isocyanate (Sumijoule 3173: manufactured by Sumitomo Bayern Urethane Co., Ltd.), and butyral resin (ESREC BM-1: Sekisui Chemical) (Manufactured) 38 parts by mass of a solution in which 15 parts by mass of methyl ethyl ketone was dissolved in 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone were mixed and dispersed in a sand mill for 2 hours using 1 mmφ glass beads to obtain a dispersion. As a catalyst, 0.005 parts by mass of dioctyltin diurarate and 4.0 parts by mass of silicone resin particles (Tospearl 145: manufactured by GE Toshiba Silicone) were added to the resulting dispersion to obtain an undercoat layer coating solution. This coating solution was applied onto an aluminum substrate by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 5 μm.

-Formation of charge generation layer-
Next, a mixture obtained by mixing 1 part by mass of chlorogallium phthalocyanine as a charge generation material with 1 part by mass of polyvinyl butyral (trade name: S-REC BM-S manufactured by Sekisui Chemical Co., Ltd.) and 100 parts by mass of n-butyl acetate. Dispersion with a glass bead with a paint shaker for 1 hour gave a dispersion for forming a charge generation layer.
This dispersion was applied on the undercoat layer by a dip coating method and then dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.15 μm.

-Formation of charge transport layer-
Next, 2 parts by mass of a compound represented by the following structural formula (1) and 3 parts by mass of a polymer compound (viscosity average molecular weight: 39000) represented by the following structural formula (2) are added to 20 parts by mass of chlorobenzene. Dissolved to obtain a coating liquid for forming a charge transport layer.

  This coating solution is applied onto the charge generation layer by a dip coating method, heated at 110 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm, and the undercoat layer, the charge generation layer, and the charge are formed on the Al substrate. An organic photoreceptor (hereinafter sometimes referred to as “non-coated photoreceptor”) in which a transport layer was laminated in this order was obtained.

-Formation of surface layer-
The surface layer was formed on the surface of the non-coated photoreceptor using a film forming apparatus having the configuration shown in FIG.
First, the non-coated photoreceptor was placed on the substrate holder 13 in the film forming chamber 10 of the film forming apparatus, and the film forming chamber 10 was evacuated through the exhaust port 11 until the pressure reached about 0.1 Pa. Next, a gas obtained by mixing He gas, hydrogen gas, and oxygen gas diluted to 4% with He by a mixing device (not shown) is introduced into the plate electrode 15 having a length of 350 mm through the gas introduction pipe 16 at about 450 sccm. (He gas 250 sccm, hydrogen 200 sccm, oxygen 2 sccm) is introduced, the high-frequency power supply unit 19 and the high-frequency power supply unit 20 set a 13.56 MHz radio wave to an output of 80 W, match with the tuner, and discharge with the plate electrode 15 It was. The reflected wave at this time was 0 W.
Next, trimethylgallium gas was introduced from the gas nozzle 17 into the film forming chamber 10 through the gas introduction pipe 18 so that the concentration was 1.0 sccm. At this time, the reaction pressure in the film forming chamber 10 measured with a Baratron vacuum gauge was 30 Pa.

  In this state, an organic photoreceptor having a surface layer provided on the surface of the charge transport layer is formed by forming a non-coated photoreceptor for 60 minutes while rotating at a speed of 100 rpm, forming a GaO film containing hydrogen having a thickness of 0.5 μm. Obtained. In the film formation, the non-coated photoconductor was not heat-treated. Moreover, what formed only the surface layer by affixing Al foil on a base | substrate on the same conditions was also created. At this time, in order to monitor the temperature at the time of film formation, the color of the thermotape previously attached to the substrate surface before film formation was confirmed after film formation, and was found to be 42 ° C.

-Analysis and evaluation of surface layer-
The composition of the sample film was measured using Rutherford back scattering. The elemental composition ratio between gallium and oxygen was 1.2 with respect to gallium 1.0. Oxygen was distributed throughout the surface layer, and hydrogen contained in the surface layer was measured by the hydrogen forward scattering method and was found to be contained in 18 atomic% of the whole.

Only the halo pattern was seen in the diffraction image obtained by RHEED (reflection high energy electron diffraction) measurement, and it was found that the film was an amorphous film.
From the above analysis and evaluation results, it was found that the surface layer formed on the surface of the non-coated photoreceptor is an amorphous film and is gallium oxide containing hydrogen and has water resistance, water repellency and sufficient hardness. .
Furthermore, the elemental composition ratio between the group 13 element and oxygen in the outermost surface portion of the surface layer was measured. The obtained results are shown in Table 1.

-Evaluation-
Next, the electrophotographic characteristics of the organic photoreceptor provided with this surface layer were evaluated. First, exposure light (light source: semiconductor laser, wavelength 780 nm, output) is applied to the non-coated photoreceptor before the surface layer formation, the surface layer formed on the Al foil, and the photoreceptor provided with the surface layer. 5 mW), while rotating at 40 rpm while scanning the surface, with a scorotron charger set to a current amount that causes the non-coated photoreceptor to be negatively charged to −700 V, after being irradiated with the charging potential and exposure light. The residual potential on the surface was measured.
As a result, the charging potential of the surface layer formed on the Al foil was 50 V / μm when converted to 1 μm thickness. On the other hand, the charging potential (initial charging potential) of the photoconductor with the surface layer was −600 V, which was a little lower. The residual potential was -130 V, and an increase in potential due to space charge was observed as compared with the charged potential of the surface layer on the Al foil. Further, the residual potential (cycle characteristics) increased by −40 V from 1 cycle to 100 cycles. Here, “cycle” means from one charge to the next. When this photoconductor was measured after one week, the residual potential decreased by 40V to -90V. The potential of the photoconductor was measured at 20 ° C. and 50% RH using a Trek model 344 surface potential meter.

  Next, the photoconductor provided with this surface layer was attached to DocuCenter Color 500 manufactured by Fuji Xerox Co., Ltd., and an image forming test was continuously performed on 200,000 sheets under a high temperature and high humidity environment (28 ° C., 80% RH). This copy printer uses a scorotron as a charger. Further, the shape factor SF1 of the toner is 130.

  As a result, both the initial stage of image formation (10th sheet) and the final stage of image formation (200,000th sheet) are slightly lower than the initial stage of image formation (10th sheet) formed using the non-coated photoreceptor. A similar image density was obtained, and a resolution of 10 lines / mm could be obtained with a clear image having no density unevenness and no image blur at the halftone dots. The wound was a fine dent.

Images obtained at the end of image formation (200,000th sheet) were evaluated based on the following criteria. Furthermore, the scratches on the surface of the photoreceptor after the completion of the image formation test were visually evaluated based on the following criteria. The evaluation results are shown in Table 1.
The amount of film thickness reduction by the film thickness measurement using the optical interference method was 10 nm on average. The measurement of the amount of film thickness reduction by the optical interferometry was carried out using a line interference film thickness meter (manufactured in-house).
From the above results, it was found that the photoconductor provided with the surface layer has improved durability and is practically satisfactory in terms of image quality such as sensitivity and image blur.

The evaluation method of each item shown in Table 1 and its evaluation criteria are as follows.
-Concentration-
In the image formation test, after adjusting the density with a non-coated photoconductor, a solid black image was printed and evaluated based on the following criteria compared with the standard print density. The standard print density was the density of the image at the initial stage (10th sheet) of image formation using a non-coated photoreceptor. Further, the comparison of the concentration was made visually.
○: Same ○-: Slightly thin Δ: Slightly thin X: Thin

-Density unevenness-
In the above image forming test, after adjusting the density with a non-coated photoconductor, the entire surface of the photoconductor is printed using a halftone pattern of 300 lines / inch with an image density of 30%, and the overall image density is uniform. Visual evaluation was made.
○: Uniform ○-: Slightly uneven Δ: Slightly uneven X: Uneven

-Fine line reproducibility-
In the above image formation test, after the density adjustment with the non-coated photoconductor, print output is performed under the conditions of 1 on and 1 off of the laser beam, and the widening of the line width is visually observed at the initial stage of image formation using the non-coated photoconductor ( The 10th image (this image is used as a standard image) was compared with 200,000 consecutive images after the image formation test.
○: Same as standard image ○-: Slightly spread Δ: Expanded X: Lines are not separated

-Image blur-
After 200,000 continuous image formation tests, a part of the photoreceptor surface was wiped with water in order to remove water-soluble discharge products.
Thereafter, a halftone image (image density of 30%) is printed, and whether or not a density difference corresponding to a location where the surface of the photoreceptor is wiped with water and a location where it is not wiped can be visually confirmed in the halftone image. Based on this, the image blur was determined. When the density difference could be easily confirmed at a glance, it was determined that the image was blurred.

-Surface scratches-
Using the optical microscope (Keyence Corporation digital microscope model VNX), the number per unit area of minute scratches having a major axis diameter of 5 μm or more was determined and evaluated based on the following criteria.
A: 10 pieces / mm ² or less B: 10-50 pieces / mm ² or less C: 50-100 pieces / mm ² or less

(Example 2 to Example 6)
In Example 1, except that the flow rate of oxygen and the discharge output were changed as shown in Table 1, film formation was performed in the same manner as in Example 1 to produce a photoreceptor, and the same as in Example 1. And evaluated. The results are shown in Table 1. However, the thickness of the undercoat layer of the organic photoreceptor was 5, 10, 20, 30, 50 μm.

(Example 7 to Example 10)
In Example 4, the discharge output was 180 W, and the amount of oxygen was changed as shown in Table 1, except that the flow rate was changed as shown in Table 1 to form a photoconductor having a surface layer formed as in Example 1. Evaluation was performed in the same manner. The results are shown in Table 1.

(Example 11 to Example 13)
In Example 1, as shown in Table 1, except that oxygen was used instead of oxygen and the flow rate and the discharge output were changed, the film was formed in the same manner as in Example 1 to produce a photoreceptor having a surface layer formed. Evaluation was conducted in the same manner as in Example 1. The results are shown in Table 1.

(Examples 14 to 15)
In Examples 14 and 15, the same procedure as in Example 1 was performed except that trimethylaluminum (TMA) was used instead of trimethylgallium (TMG), nitrogen was used, and the flow rate and discharge output were changed as shown in Table 1. A photoreceptor having a surface layer formed thereon was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Examples 1 and 2)
As shown in Table 1, except that the thickness of the undercoat layer was changed, film formation was performed in the same manner as in Example 2 to produce a photoconductor having a surface layer formed, and evaluation was performed in the same manner as in Example 1. did. The results are shown in Table 1.
In Comparative Example 1, the charge potential of the surface layer is low, but a large amount of space charge is generated, the change of the residual potential is small, the image density is low, the image unevenness is large, and is not suitable for practical use.
In Comparative Example 2, the decrease due to the residual potential is large, but the charge accumulation in the undercoat layer is large, the image density is low, the image unevenness is large, and it is not suitable for practical use.

(Comparative Examples 3 and 4)
In Example 7, except that the flow rate of oxygen was changed as shown in Table 1, film formation was performed in the same manner as in Example 1 to produce a photoreceptor, and evaluation was performed in the same manner as in Example 1. did. The results are shown in Table 1.

(Comparative Examples 5 and 6)
In Example 11, except that the flow rate of nitrogen was changed as shown in Table 1, film formation was performed in the same manner as in Example 1 to produce a photoconductor having a surface layer, and evaluation was performed in the same manner as in Example 1. did. The results are shown in Table 1.

(Comparative Examples 7 and 8)
In Example 14, except that the flow rate of nitrogen was changed as shown in Table 1, film formation was performed in the same manner as in Example 1 to produce a photoreceptor having a surface layer, and evaluation was performed in the same manner as in Example 1. did. The results are shown in Table 1.

(Example 16)
The photoconductor of Example 8 was attached to DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and 200,000 continuous image forming tests were performed under a high temperature and high humidity environment (28 ° C., 80% RH). This copy printer uses a roll charger. The hood cleaning pressure was 10 kgf / cm.
As a result, both the initial image formation (10th sheet) and the final image formation (200,000th sheet) are the same as the initial image formation (10th sheet) formed using the non-coated photoreceptor. An image density was obtained, and a resolution of 10 lines / mm could be obtained with a clear image having no density unevenness and no image blur at the halftone dots.

Further, the hood cleaning pressure was changed from 4 kgf / cm to 35 kgf / cm, and the presence or absence of cleaning failure due to the difference in the hood cleaning pressure was visually evaluated. Further, the number of scratches on the photoreceptor surface was counted. The obtained results are shown in Table 2.

(Comparative Example 9)
In Comparative Example 9, the undercoat layer was 3 μm, the thickness of the photosensitive layer was changed only to the charge transport layer to 22 μm, the total thickness was 25 μm, and the same thickness as in Example 1 was prepared and evaluated in the same manner. did. The obtained results are shown in Table 1.

It is sectional drawing which shows an example of the laminated constitution of the electrophotographic photoreceptor of this embodiment. It is sectional drawing which shows an example of the laminated constitution of the electrophotographic photoreceptor of this embodiment. It is a schematic diagram which shows an example of the film-forming apparatus. 1 is a schematic configuration diagram illustrating a quadruple tandem full-color image forming apparatus. It is a schematic block diagram which shows a suitable example of a process cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 Undercoat layer 3 Photosensitive layer 3A Charge generation layer 3B Charge transport layer 4 Surface layer 10 Deposition chamber 11 Exhaust port 12 Substrate rotating part 13 Substrate holder 14 Substrate 15 Flat plate electrode 16 Gas introduction part 17 Gas nozzle 18 Gas introduction Part 19 High-frequency power introduction part 20 High-frequency power supply part

Claims (14)

  An element containing at least a conductive substrate, an undercoat layer having a thickness of 5 μm to 50 μm in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, a group 13 element and oxygen, and an oxygen element relative to the group 13 element An electrophotographic photoreceptor comprising a surface layer having a composition ratio of 0.9 or more and 1.4 or less in this order.   An element containing at least a conductive substrate, an undercoat layer having a thickness of 5 μm or more and 50 μm or less in which a conductive filler is dispersed in an organic polymer, an organic photosensitive layer, a group 13 element and nitrogen, and an element for nitrogen of the group 13 element An electrophotographic photoreceptor comprising a surface layer having a composition ratio of 0.4 or more and 0.8 or less in this order.   3. The electrophotographic photoreceptor according to claim 1, wherein an elemental composition ratio of oxygen in the outermost surface portion of the surface layer to a group 13 element is 1.4 or more and 1.6 or less.   The electrophotographic photoreceptor according to claim 1, wherein the surface layer further contains hydrogen. The electrophotographic photoreceptor according to claim 1 or 2,
Charging means for charging the surface of the electrophotographic photoreceptor;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor;
Image forming means for developing a latent electrostatic image formed on the surface of the electrophotographic photoreceptor using a developer containing at least a toner to form a toner image;
Transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the transfer target;
An image forming apparatus comprising: a fixing unit configured to fix the toner image transferred to the surface of the transfer target.   The image forming apparatus according to claim 5, wherein a shape factor SF1 of the toner is 100 or more and 140 or less.   The image forming apparatus according to claim 5, wherein the developer further includes a resin-coated carrier.   The image forming apparatus according to claim 5, further comprising a cleaning unit that removes residual toner on the surface of the electrophotographic photosensitive member after the transfer.   The image forming apparatus according to claim 8, wherein the cleaning unit is a cleaning blade.   The image forming apparatus according to claim 9, wherein a pressing force of the cleaning blade to the surface of the electrophotographic photoreceptor is 5 gf / cm or more and 25 gf / cm or less.   The image forming apparatus according to claim 9, wherein the cleaning unit further includes an electrostatic brush disposed on an upstream side of the cleaning blade.   A carrier that is arranged downstream of the image forming unit and upstream of the transfer unit and collects illegal carriers transferred to the surface of the electrophotographic photosensitive member together with toner when forming the toner image by a magnetic force. The image forming apparatus according to claim 5, further comprising a collecting unit.   The image forming apparatus according to claim 5, wherein the charging unit is a contact charger. The electrophotographic photoreceptor according to claim 1 or 2,
A charging means for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member, and a developer containing at least a toner. Image forming means for developing an electrostatic latent image formed on the surface of the photoconductor to form a toner image, and illegal carriers transferred to the electrophotographic photoconductor surface together with the toner when the toner image is formed are captured by magnetic force. Carrier collecting means for collecting, transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the transfer target, fixing means for fixing the toner image transferred to the surface of the transfer target, and after transfer And at least one selected from the group consisting of cleaning means for removing residual toner on the surface of the electrophotographic photoreceptor.
A process cartridge that is removable from the main body of the image forming apparatus.

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