JPH01217355A - Image forming method - Google Patents

Abstract

PURPOSE:To solve problems on image defects, such as black spots, and to obtain good characteristics of a photosensitive body by incorporating a specified azo compound in a carrier generating layer and forming a carrier blocking layer between a conductive substrate and the carrier generating layer. CONSTITUTION:The carrier generating layer contains at least one of couplers represented by formula I in which Ar<1> is aryl; each of Y and Z is halogen, cyano, or the like; (s) is 0-4; and (r) is 0-2, and as the carrier generating material, the compound having an azo group in the molecule. The carrier blocking layer containing at least one of polyvinyl butyral and polyvinyl formal and titanium oxide subjected to no conductivity enhancing treatment is formed between the conductive substrate and the carrier generating layer, thus permitting a good image free from image defects, such as black spots, to be obtained in reversal development, and high-quality images free from fog and high in image density to be obtained even under environments of high temperature and high humidity, and low temperature and low humidity, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming method, and particularly to an electrophotographic copying method.

In the electrophotographic copying method of the prior art Carlson method, after the surface of a photoreceptor is charged, an electrostatic latent image is formed by exposure, and the electrostatic latent image is developed with toner, and then the visible image is formed. Transfer and fix onto paper, etc. At the same time, the photoreceptor is subjected to removal of adhered toner, neutralization of static electricity, and surface cleaning, and is used repeatedly over a long period of time.

Therefore, as an electrophotographic photoreceptor, it is important to not only have electrophotographic properties such as good charging characteristics and sensitivity, and low dark decay, but also physical properties such as printing durability, abrasion resistance, and moisture resistance after repeated use. It is also required to have good physical properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance).

Conventionally, as electrophotographic photoreceptors, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have been widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, in Japanese Patent Publication No. 50-10496, poly-N
-vinylcarbazole and 2.4.7-dolinitro9-
Organophotoreceptors are described having photoreceptors containing fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the carrier generation function and carrier transport function to different substances in the photosensitive layer. ing. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible. Therefore, it is expected that organic photoreceptors with high sensitivity and durability can be obtained.

FIG. 6 shows a functionally separated electrophotographic photoreceptor using such an organic photoconductive substance.

This electrophotographic photoreceptor has a structure in which a carrier generation layer 6 and a carrier transport layer 4 are sequentially laminated on a conductive substrate 1, and is used for negative charging. That is, the photosensitive layer 8 is composed of the carrier generation layer 6 and the carrier transport layer 4.

In an electrophotographic photoreceptor having the above-mentioned layer structure, since the mobility of holes is higher than that of electrons when used with negative charging, it is possible to use photoconductive materials with hole transport properties that have good properties. This is advantageous in terms of sensitivity, etc.

In contrast, few electron-transporting materials have excellent properties or are carcinogenic, making them unsuitable for use. For this reason, the above-mentioned photoreceptor is used for negative charging. In this case, it is advantageous to use a material with a high hole transport ability in order to achieve high sensitivity.

However, in the above-mentioned photoreceptor, carrier injection from the conductive substrate or lower layer side tends to occur when negatively charged, as shown in FIG. 6, and as a result, the surface charge disappears microscopically, or It will decrease. Although the cause of such local carrier injection is not clear, it is thought to be due to defects or non-uniformity on the surface of the conductive substrate, non-uniformity in the charge generation layer, or the like.

Such local carrier injection causes the following problems.

That is, recently, reversal development has been widely adopted in printers that involve digital processing, but in the reversal development method, a toner image is formed on the exposed area (the area where the surface charge has disappeared, VL)1, and the toner image is formed on the unexposed area (VL). No toner image is formed in the areas (portions where surface charges are retained, ■+, ()).

However, in the reversal development method, when the surface charge microscopically disappears or decreases in the unexposed area due to carrier injection from the substrate or lower layer as described above, toner is developed in that area, resulting in so-called fog. It becomes an image. This type of capri is different from normal fog, and is a phenomenon that occurs when the surface charge on the photoreceptor microscopically disappears or decreases during reversal development as described above, and is called "black spot". There is. These black spots are localized spots of toner on a white background, so they are much more noticeable than when a black background is white, and they significantly reduce the quality of the image, resulting in an inappropriate image. It is a defect.

As a way to solve these problems, the carrier transport layer 4
In this case, it is conceivable to reduce the content of carrier transport material (hereinafter sometimes referred to as CTM) or change the type of CTM or binder resin. All of these are intended to reduce the hole transport ability of the carrier transport layer 4 and suppress carrier injection to the surface of the photoreceptor, but in this photoreceptor, there is a decrease in photosensitivity, an increase in residual potential, lV, This results in an increase in 1, a decrease in 1V and 1 stability during repeated use, and a decrease in temperature characteristics, and particularly at low temperatures, the photoreceptor characteristics are greatly deteriorated, such as an increase in 1VL1.

On the other hand, in FIG. 6, it is also conceivable to provide a charge blocking layer between the carrier generation layer 6 and the conductive substrate 1 to block carrier injection from the conductive substrate 1. However, in this case, transport of photocarriers generated even during light irradiation is suppressed and blocked by the blocking layer, and residual potential increases during repeated use, resulting in insufficient image density. In addition, the temperature characteristics are greatly deteriorated, and for example, under low temperature and low humidity conditions, the image density is insufficient from the beginning, which is extremely inconvenient. Furthermore, when coating the carrier generation layer 6 on such a charge blocking layer, depending on the type of carrier generation substance, the carrier generation substance may aggregate, resulting in poor coating, resulting in an increase in black spots, a decrease in image density, and even damage to the image. This also led to unevenness and caused significant inconvenience.

On the other hand, as countermeasures from a process perspective, charging potential VH and bias voltage ■. , but in this case, the potential of the exposed area ■, and the bias voltage ■Dc
Since the difference between the two images becomes smaller, the image density decreases.

As described above, there has been no known photoreceptor that eliminates image defects such as black spots and has good photoreceptor characteristics, and a technical solution to these mutually contradictory problems has been desired.

Furthermore, in recent years, semiconductor laser light sources have been used in electrophotographic copying methods, which are inexpensive, compact, and capable of direct modulation. Currently, gallium-aluminum-arsenic (Ga-A) is widely used in semiconductor lasers.
The 11-As) type light emitting device has an oscillation wavelength of about 750 nm or more. Many studies have been made in the past in order to obtain electrophotographic photoreceptors that are highly sensitive to such long wavelength light. For example, a method was considered to add a new sensitizer to a photosensitive material such as selenium or cadmium sulfide, which has high sensitivity in the visible light region, to extend the wavelength to a longer wavelength. The environmental resistance against
It is also toxic and has problems in practical application. Furthermore, the sensitivity of many known organic photoconductive materials is usually 700.
Since there are few materials that are limited to the visible light region of nm or less and have sufficient sensitivity to wavelengths longer than this, it has been difficult to use them in laser printers that use semiconductor laser light sources that are expected to be highly reliable.

Technological systems using such laser beams and the like are expected to be applied to printers, which is why the emergence of a useful image forming method using reversal development is desired.

The purpose of the present invention is to obtain good images without image defects such as black spots in reversal development where black spots are likely to occur, and to prevent fogging even in environments of high temperature, high temperature, low temperature and low humidity. An object of the present invention is to provide an image forming method capable of obtaining a high-quality image with high image density without any image distortion, and stably supplying a uniform image with high image density even during repeated use.

26 Structure of the invention and its effects The present invention provides an image forming method using a photoreceptor having a photoreceptor layer comprising a carrier transport layer provided on a carrier generation layer. A carrier generation layer containing a compound having a coupler represented by (1) and having at least two azo groups in the molecule as a carrier generation substance; and at least one of polyvinyl butyral and polyvinyl formal. (b) using a photoconductor containing titanium oxide that has not been subjected to conductive treatment and having a charge blocking layer provided between the carrier generation layer and the conductive substrate; The absolute value of is 400V~9
The present invention relates to an image forming method characterized in that reversal development of the electrostatic latent image is performed by applying a DC bias voltage having a charge of 00V.

- Noshiro [I]: [However, in the above - Noshiro, Ar' represents an aryl group, Y and Z are a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, or represents a substituted or unsubstituted alkoxy group, S represents 0-4, and r represents 0-2. ] However, the charging potential and the DC bias voltage have the same sign.

In the present invention, a specific azo compound having a coupler represented by the above-mentioned -Noshiro (I) is contained as a carrier-generating substance in a carrier-generating layer, and is provided between this carrier-generating layer and a conductive substrate. A remarkable feature is that the materials and contents of the charge blocking layer are specified.

That is, by providing a charge blocking layer between the conductive substrate and the carrier generation layer, it is possible to prevent the occurrence of black spots during reversal development. The reason for this is not clear, but -
It can be thought of as follows.

That is, in the conventional photoreceptor as shown in FIG.
Carriers (holes) injected from the substrate 1 side easily pass through the carrier generation layer 6 and reach the surface of the photoreceptor via the carrier transport layer 4 having high hole transport properties. In other words, the carrier generation layer 6 cannot function as a barrier to local carrier injection.

In contrast, in the present invention, by providing a charge blocking layer between the substrate and the carrier generation layer, it is possible to provide a barrier against local carrier injection from the conductive substrate side. It is thought that this can prevent the loss and decrease of surface charge caused by

Therefore, when reversal development is performed, no black spots are produced on the image, and a remarkable effect can be achieved in that a high-quality image without image defects can be obtained.

It is thought that the reason why the charge blocking layer is able to exhibit such a function is that the electrical resistance of the charge blocking layer itself is maintained at a high level due to the action of the binder material and the titanium oxide that has not been subjected to conductive treatment. The formulation of the charge blocking layer is important.

However, another important thing here is the selection of the carrier generating substance and the material of the charge blocking layer, and the combination of the two.

That is, since the carrier generation layer is formed by coating directly on the charge blocking layer and is itself extremely thin, depending on the combination of the carrier generation substance and the material of the charge blocking layer, the carrier generation substance may aggregate or This is extremely inconvenient because coating defects occur, black spots increase significantly, photosensitivity decreases, and image unevenness occurs.

However, when it comes to selecting a suitable combination that will not cause coating defects from among the countless existing polymeric materials and numerous carrier-generating substances, there is no uniform selection method. The reality is that we have no choice but to determine a good combination through repeated experiments.

As a result of various studies, the present inventor has found that extremely good results can be obtained by selecting a combination of the above-mentioned specific Ab compound and polyvinyl butyral and/or polyvinyl formal as a binder substance. I found it.

In other words, the above-mentioned specific azo compound has excellent photosensitivity, and by using this compound as a carrier generating substance, the potential stability during repeated use of the photoreceptor is improved, there is little memory phenomenon, and there is no residual potential. It is small and stable. Moreover, since this azo compound has high sensitivity in a long wavelength region, it is possible to provide a high-performance photoreceptor that is particularly suitable for image forming methods by reversal development using a semiconductor laser as a light source.

Furthermore, by containing at least one of polyvinyl butyral and polyvinyl formal in the charge blocking layer, the above-mentioned ab compounds do not aggregate during the coating formation of the carrier generation layer, and therefore, black body and image unevenness can be prevented in reversal development. At the same time, the azo compound is uniformly dispersed in the carrier generation layer, and the inherent photosensitivity of the Ab compound can be exhibited without hindering it.

Therefore, a high quality and uniform image can be provided, and the image density can also be increased.

Moreover, it is important to specify not only the material of the charge blocking layer, but also the substances contained in it.This allows us to solve the technical problem of preventing black spots, which is essential for reversal development, as well as controlling temperature and humidity. Excellent characteristics (IT environment characteristics),
It is noteworthy that it can provide good images even under high temperature and high humidity conditions as well as under low temperature and low humidity conditions.

In other words, since devices such as printers are used for long periods of time under various conditions, they are exposed to extremely high temperatures, low temperatures and low humidity, and it is important to provide good images even at low temperatures. This is why this is required.

In this regard, in the present invention, negative photocarriers generated within the carrier generation layer during light irradiation are transported within the charge blocking layer by titanium oxide that has not been subjected to conductive treatment.
It is believed to be transferred to the conductive substrate. That is, it is considered that the charge blocking layer was given electron conductivity by the action of titanium oxide. Therefore, the movement of photocarriers becomes smooth, making it possible to increase photosensitivity, reduce residual potential during repeated use, and increase image density. therefore,
The image density will not be insufficient even when used repeatedly, and sufficient image density can be obtained especially under low temperature and low humidity conditions. Furthermore, even under high temperature and high humidity conditions, the carrier generation layer is a thin film and can suppress an increase in dark decay, so that no fogging occurs.

Moreover, the high resistance of the layer is maintained by including titanium oxide that has not been subjected to conductive treatment in the charge blocking layer.If titanium oxide that has been treated to conductivity is used, carrier injection would be It is thought that the charge blocking function cannot be effectively blocked, and black spots appear on the image.

Furthermore, what should be noted about the present invention is that in addition to the above, the absolute value of the charging potential represented by lVwl is limited to a specific range of 1Vhl=400V to 900■, so that The defects described above do not occur. That is, iV
, I < 400 V, it is difficult to obtain the required electric field strength, but when IV, ++ > 900 V, the thickness of the photosensitive layer becomes large for this purpose, which reduces the sensitivity. Undesirable. Furthermore, in the present invention, IVHl
It is also important that IVHI-IVDcI, which is the difference between 1v and 1v (absolute value of DC bias voltage), is specified as 0 to 200V. That is, JV+-++ IVJ
If <0■, fog will occur and t
If vHI Iv D (:l>200 V), carrier adhesion (when using a two-component developer) or adhesion of toner of opposite polarity (when using a bipolar component developer) will occur.

Therefore, according to the invention, jV,I =400-90
It should be 0■ (preferably 500 to 700V),
And IVH11Vpcl should be O ~ 200 V (preferably 50 ~ 150 ■), and performing reversal development under these conditions will maintain high sensitivity and obtain a good image with high image quality and no black spots. This is an essential condition for

When the present invention is applied to a reversal development method, especially when applied to a printer, the character area (black background area) has a smaller area (that is, the exposed area is smaller) than the white background area, and the normal This method is advantageous in terms of preventing deterioration of the photoreceptor, etc., compared to the development method.

Next, the effects when the present invention is applied to a laser light source will be described. As mentioned above, laser printers are a promising technological field, but conventionally, when forming an image by irradiating semiconductor laser light using a photoreceptor like the one shown in Figure 6, it was difficult to print a solid image. In the image, density unevenness in the form of interference fringes called moiré occurred. Therefore, there has been a need for an image forming method that can eliminate moiré.

Various measures can be taken to prevent such moiré.

For example, it is possible to appropriately roughen the surface of the conductive substrate to prevent interference. However, this method significantly increases the black spots during reversal development, making it impractical.

On the other hand, it is also possible to prevent interference by increasing the thickness of the carrier generation layer and increasing the absorbance within the carrier generation layer. However, such photoreceptors have a drawback in that their characteristics are insufficient, particularly in that their temperature and humidity characteristics are significantly deteriorated.

That is, in reversal development, under high humidity conditions, fogging occurs on the image, while under low humidity conditions, image density is insufficient, and moreover, the occurrence of black spots becomes noticeable.

In contrast, in the present invention, even when an electrostatic latent image is formed by irradiation with a laser light source, it is possible to prevent density unevenness in the form of interference fringes and obtain a uniform image.

The reason for this is assumed to be as follows.

The cause of the interference fringe-like density unevenness on the image is not clear, but it is thought to be caused by a core fire.

As shown in FIG. 7, when the surface of the photoreceptor shown in FIG. A part of the light enters the photosensitive layer 8, is reflected by the substrate surface 1a, and is emitted as an emitted light 18. At this time, if the curvature index of the photosensitive layer is n, the thickness is d, and the wavelength of the semiconductor laser beam is λ, and if the laser beam 16 is incident perpendicularly to the photosensitive layer 8, then there is a gap between the light 17 and the light 18 ( This results in an optical path difference of 2nd-λ/2). Since the laser beam is coherent, interference occurs between the beams 17 and 18, and when nd is an integral multiple of λ/2, the intensity of the reflected light is maximum, that is, it enters the inside of the carrier transport layer 4. When the intensity of light is minimal (according to the law of conservation of energy) and nd is an odd multiple of λ/4, the reflected light is minimal, that is, the light entering the interior is maximal. Incidentally, due to manufacturing reasons, d has an unavoidable local unevenness of about 1 μm.

Since the laser beam has good monochromaticity and is coherent, the above-mentioned interference condition changes in response to the unevenness in the location of d, causing unevenness in the absorption amount of the laser beam in the carrier generation layer 6, which causes the solid image to become uneven. It is thought that this appears as interference fringes of density. Note that in normal copying machines, the light source is not monochromatic light, so the intensity of the density unevenness in the form of interference fringes changes depending on the wavelength, and is averaged out and cannot be seen.

In contrast, according to the present invention, a charge blocking layer is provided between the conductive substrate and the photosensitive layer, and this charge blocking layer contains the above-mentioned specific binder resin and titanium oxide that has not been subjected to conductive treatment. Therefore, the light incident on the charge blocking layer is scattered due to the dispersion state of titanium oxide.

As a result, interference will not occur, and it is thought that unevenness in the intensity and location of reflected light due to interference will also no longer occur.

FIG. 1 illustrates a general configuration of a photoreceptor, such as an electrophotographic photoreceptor, used in the present invention.

In the photoreceptor shown in FIG. 1, a carrier generation layer 6 is provided on a conductive substrate 1 via a charge blocking layer 7, and a carrier transport layer 4 is provided on the carrier generation layer 6. 8 indicates a photosensitive layer.

In the photoreceptor shown in FIG. 1, an intermediate layer having a blocking function or the like may be provided between the carrier generation layer and the carrier transport layer. Further, a protective layer (protective film) may be formed on the surface of the photoreceptor in order to improve printing durability, for example, a synthetic resin film may be coated.

Generally, in the carrier generation layer, a particulate carrier generation substance and a carrier transport substance are bound together by a binder substance. That is, they are dispersed in the layer in the form of pigments.

Next, a specific azo compound used as a carrier generating substance in the present invention will be described.

This is a compound that has a coupler represented by the general formula [■] in its molecule and at least two azo groups.

Specifically, there are disazo compounds having two azo groups in the molecule, trisazo compounds having three azo groups, and compounds having four or more azo groups.

Examples of the disazo compound include those shown in Noshiro (n) below.

General formula [■]: Cp-N=N-D-N=N-CP [However, as D, ○ 0)・CHa CN
CN Also, as other ab compounds, the following -
Noshiro% formula% General formula [■]: Cp-N=N-Ar2-N-Ar3-N=N-CpAr
4 N=N-Cp General formula [■]; Cp-N=N-A r 2-N=N-A r 3-N=
N-Cp-Noshiro [V]: Cp -N=N-A r 2-N=N-A r 3-N
=N-Ar''-N=N-Cp [However, Ar2, Ar3, and Ar4 each represent a substituted or unsubstituted carbocyclic aromatic ring group, or a substituted or unsubstituted heterocyclic aromatic ring group .

Further, specific examples of A r 2, Ar", and Ar' are illustrated. Furthermore, examples of Cp (coupler) include the following.

[However, for A, specific trade names of polyvinyl butyral include Denka Butyral #4000 and Denka Butyral #300.
0 (manufactured by Denki Kagaku Kogyo Co., Ltd.), XYHL (manufactured by Union Carbide), S-LEC BM-2, S-LEC B
M-5, S-LEC BM-1, S-LEC BL-1, S-LEC BL-3, S-LEC BL-7, S-LEC B
Examples include XL, S-LEC BH-3 (manufactured by Block Chemical Industry Co., Ltd.), and the like.

A specific trade name of polyvinyl formal is ``non-Denka formal titanium oxide'' such as ``Denka formal #20'' with a specific resistance of 108 Ω·1 or more.

The titanium oxide is preferably granular with an average particle diameter of 1 μm or less, more preferably 0.1 to 0.4 μm.

Here, the above-mentioned "average particle size" may be measured by directly selectively counting with an electron microscope, or may be measured from particle size distribution using a laser beam or the like. It can also be calculated as a sphere from the specific surface area. Other known methods can also be used.

Titanium oxide may be subjected to treatments other than conductive treatment, and main treatment agents include aluminum, silicon, zinc, nickel, antimony, chromium, and the like.

As a pretreatment for titanium oxide, various ions present as impurities can be cleaned or ion exchange treatment can be performed. It is also possible to improve dispersibility by treating the particle surface with a coupling agent.

The specific product name is high purity titanium oxide rCR-E.
LJ, ultrafine titanium oxide rTTO-55, sulfuric titanium oxide rR-55, OJ, rR-630J, rR-
680J, rR-670J, rR-”580J, rR-
780J, rA-100J, rA-220J, rW-1
0J, chlorinated titanium oxide rcR-raO'', rCR-60
J, rCR-60-2J, rCR-67J, rCR-5
8J (manufactured by Ishiya Sangyo Co., Ltd.) and the like are exemplified.

The thickness of the charge blocking layer is preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm. Further, in the charge blocking layer, the content ratio (weight ratio) of titanium oxide that has not been subjected to conductive treatment to the binder substance is preferably within the range of (1:10) to (10:1).

In the carrier generation layer, the content ratio of the carrier generation substance to the binder substance is preferably 3/1 to 1/10, more preferably 2/1 to 1/3.

The thickness of the carrier generation layer is preferably 0.1 μm or more, and more preferably within the range of 0.2 to 5 μm.

The thickness of the carrier transport layer is preferably 10 μm or more.

The thickness of the entire photosensitive layer is preferably within the range of 10 to 40 μm, and more preferably within the range of 15 to 30 μm. If the film thickness is smaller than the above range, the charging potential will be lower due to the thinner film, and the stiffness resistance will also tend to decrease. Furthermore, if the film thickness is larger than the above range, the residual potential will increase on the contrary, and the same phenomenon as described above will occur when the carrier generation layer is too thick, making it difficult to obtain sufficient transport performance. Therefore, the residual potential tends to increase during repeated use.

It is also possible to include a carrier transport substance in the carrier generation layer.

When a photosensitive layer is formed by dispersing a granular carrier-generating substance, the carrier-generating substance is preferably in the form of powder particles with an average particle size of 2 μm or less, preferably 1 μm or less, and more preferably 0.5 μm. preferable.

Furthermore, in the carrier transport layer, the carrier transport substance is
Those having excellent compatibility with the binder substance are preferred.

As a result, turbidity and opacity do not occur even if the amount of the binder substance is increased, so the mixing ratio with the binder substance can be set at a very wide range. The layer is uniform and stable, resulting in better sensitivity and charging characteristics, and a photoreceptor that can form clear images with higher sensitivity can be obtained. Furthermore, especially when used in repetitive transfer electrophotography,
It is possible to achieve the effect that fatigue deterioration is less likely to occur.

In the present invention, it is also possible to use one or more other carrier-generating substances in combination with the above-described azo compound having a coupler. Examples of carrier-generating substances that can be used in combination include anthraquinone pigments, perylene pigments, polycyclic quinone pigments, methine squaric acid pigments, cyanine dyes, and azulenium compounds.

The carrier transport substances used in the present invention include carbazole derivatives, oxazole derivatives, oxadiazole derivatives,
Thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives,
imidapridine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives,
Oxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, hensifuran derivatives, acridine derivatives, phenazine derivatives, aminostilhene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilhene derivatives, poly-N-vinylcarbazole, poly-1 -vinylpyrene, poly-9
- It may be one or more selected from vinylanthracene and the like.

Specific examples of such carrier transport substances are disclosed in Japanese Patent Application No. 1983.
-195881. The general formula is listed below.

The following general formula [■] or [■] as a carrier transport substance
styryl compounds can be used.

-Noshiro (■): \ (However, in this -Noshiro, R1, R2 represent substituted or unsubstituted alkyl groups, aryl groups, and substituents include alkyl groups, alkoxy groups, substituted amino groups, hydroxyl groups, and halogen atoms. , using an aryl group.

ArS, Ar6: represents a substituted or unsubstituted aryl group, and as a substituent, an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, or an aryl group is used.

R3 and R4 represent a substituted or unsubstituted aryl group or a hydrogen atom, and the substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an aryl group. ) General formula [■]: (However, in this Noshiro, RS, substituted or unsubstituted aryl group, R6, hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, amino group, substituted amiki group) , hydroxyl group, R7 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group.) In addition, as a carrier transport substance, the following general formula [■], (I
X), (IXa, :], (IXb:l or [x]) of the tracine compounds can also be used.

General formula (■): \R11 (However, in this -Noshiro, R8 and REI are each a hydrogen atom or) \rogen atom, R''. and Rp: each substituted or unsubstituted aryl group, Ar7: substituted or unsubstituted Represents a substituted arylene group.

) General formula [■]: (However, in this -Noshiro, R''2 represents a substituted or unsubstituted oryl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted heterocyclic group, R゛ゝR14, a hydrogen atom, an alkyl group, a substituted or R'< represents an unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.), -Noshiro (IXa): IT (However, this - In Noshiro, Rlb: methyl group, ethyl group, 2-hydroxyethyl group or 2-chloroethyl group, R1? dimethyl group, ethyl group, benzyl group or haphenyl group, R11, methyl group, ethyl group, benzyl group or phenyl group ) General formula (IXb): (However, in this Noshiro, R''1 is a substituted or unsubstituted naphthyl group; R'° is a substituted or unsubstituted alkyl group, aralkyl group, or aryol group. ;R'1 is a hydrogen atom, an alkyl group, or an alkoxy group; R'' and R2S are the same or different groups consisting of a substituted or unsubstituted alkylaralkyl group or an aryl group.) General formula [X]: (However, in this Noshiro, RL'': a substituted or unsubstituted ary-J group or a substituted or unsubstituted heterocyclic group, R21: a hydrogen atom, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aralkyl group) Aryl group, Q: hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group, or cyano group, S: represents an integer of O or l.) In addition, as a carrier transport substance, the following general formula (XI) pyrazoline compounds can also be used.

- Noshiro (XI): H R'' (However, in this - Noshiro, Il: 0 or IP and R''7: substituted or unsubstituted aryl group, R'': substituted or unsubstituted aryl group or heterocyclic group , Ra) and RJ-, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group or aralkyl group (however, R'' and R'' are not both hydrogen atoms, and When the above ! is 0, Raj is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula (XII) can also be used as a carrier transport substance.

- Noshiro (Xll): / Ar'' (However, in this - Noshiro, Ar8, Ar'': represents a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, a nitro group, or an alkoxy group is used as a substituent.

Ar": Represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group, or heterocyclic group, and substituents include an alkyl group, an alkoxy group, a halogen atom, a water β group, an aryloxy group, an aryl group. , an amino group, a nitro group, a piperidino group, a morpholino group, a naphthyl group, an anthryl group, and a substituted amino group.However, an acyl group, an alkyl group, an aryl group, and an aralkyl group are used as a substituent for the substituted amino group.) , compounds of the following general formula (XTII:) can also be used as carrier transport materials.

General formula (Xll): (However, in this -Noshiro, Ar'"; represents a substituted or unsubstituted arylene group, R
"", R32, RE) and R3"; represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) Furthermore, compounds of the following general formula (XTVI) Can be used as a carrier transport material.

General formula (XIV): (However, in this Noshiro, RIf, RJl, RJ) and R'' are each a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a benzyl group, or The aralkyl group, R3q and R″ are
1 hydrogen atom, substituted or unsubstituted carbon atom, respectively
~40 alkyl groups, cyclonal-1L4, alkenyl groups, cycloalkenyl groups, aryl groups or aralkyl groups (provided that RIf and R4o jointly have 3 to 1 carbon atoms)
o may form a saturated or unsaturated hydrocarbon ring. ), R4'', R4', R1' and Rn are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, an amine group , an alkylamino group, or an arylamino group.) An antioxidant can be contained in the carrier transport layer and the carrier generation layer.This can suppress the influence of ozone generated during discharge, and reduce the residual potential during repeated use. It is possible to prevent the charge potential from increasing and decreasing the charged potential.

Examples of the antioxidant include hindered phenol, hindered amine, paraphenylene diamine, aryl alkane, hydroquinone, spirochroman, spiroindanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, and the like.

These specific compounds are disclosed in Japanese Patent Application No. 61-1628.
No. 66, No. 61-188975, No. 61-19587
No. 8, No. 61-157644, No. 61-195879
No. 61-162867, No. 61-204469, No. 61-217493, No. 61-217492, and No. 61-121541.

A polymeric organic semiconductor can also be included in the photosensitive layer.

Among these high-molecular organic semiconductors, poly-N-vinyl hardened resin or its derivatives are highly effective and are preferably used. Such poly-N-vinylcarbazole derivatives are those in which all or part of the carbazole ring in the repeating unit is substituted with various substituents, such as an alkyl group, a nitro group, an amino group, a hydroxy group, or a halogen atom. be.

Furthermore, at least one type of electron-accepting substance can be contained in the photosensitive layer for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, and the like.

In the present invention, the electron-accepting substances that can be used in the photoreceptor include:
For example, succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4
-Nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, m-dinitrobenzene,
1.3.5-) Dinitrobenzene, varanitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, brumanil, 2-methylnaphthoquinone, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenyl Lidecy [dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidecy [dicyanomethylenemalonodinitrile], picric acid, 0-nitrobenzoic acid, p-nitrobenzoic acid, 3.5-dinitrobenzoic acid, penta Fluorobenzoic acid, 5-nitrosalicylic acid,
Examples include 3,5-dinitrosalicylic acid, -phthalic acid, mellitic acid, and other compounds with high electron affinity. Among these, fluorenone type, quinone type, C! , CN', N2O'2, and other benzene derivatives having electron-withdrawing substituents are particularly preferred.

Furthermore, silicone oil or a fluorine-based surfactant may be present as a surface modifier. Further, an ammonium compound may be contained as a durability improver.

Furthermore, an ultraviolet absorber may be used.

Preferred ultraviolet absorbers include nitrogen-containing compounds such as benzoic acid, stilpene compounds and their derivatives, triazole compounds, imidazole compounds, l-lyazine compounds, coumarin compounds, oxadiazole compounds, thiazole compounds and their derivatives. is used.

Examples of binder resins that can be used for the constituent layers of the photoreceptor include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, polyester resin, alkyd resin, polycarbonate resin, and melamine resin. , methacrylic resin, acrylic resin, polyvinylidene chloride,
Addition polymer resins such as polystyrene, lid addition resins, polycondensation resins, copolymer resins containing two or more of these repeating units, insulating resins such as vinyl chloride-vinyl acetate copolymer resins, styrene -butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, etc.
□Further examples include polymeric organic semiconductors such as N-vinylcarbazole.

The above binders can be used alone or as a mixture of three or more.

As a binder for the protective layer provided as necessary,
Volume resistance 108 Ω・cm or more, preferably lOpa Ω・c
A transparent resin having a resistance of 10 mm or more, more preferably 10" Ωcm or more is used. Also, a resin that is cured by light or heat may be used. As a resin that is cured by light or heat, for example, a thermosetting resin is used. Acrylic resins, epoxy resins, urethane resins, urea resins, polyester resins, alkyd resins, melamine resins, photocurable cinnamic acid resins, etc., or copolymers or condensation resins thereof, and other materials that can be used in electrophotographic materials. The protective layer may contain less than 56% thermoplastic resin if necessary for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Such thermoplastic resins include, for example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polycarbonate resin, or copolymer resins thereof, poly-N - Polymeric organic semiconductors such as vinyl carbabul and other thermoplastic resins used in electrophotographic materials can all be used.

The carrier generation layer can be provided by the following method.

(a) A method in which a binder and a solvent are added to a carrier-generating substance, mixed and dissolved, and a solution is applied.

(b) A method in which a carrier-generating substance, etc. is made into fine particles in a dispersion medium using a ball mill, a homomixer, a sand mill, an ultrasonic disperser, an attritor, etc., and a binder is added, mixed and dispersed, and the resulting dispersion is applied.

Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion.

Further, the carrier transport layer can be formed by applying and drying the above-mentioned carrier transport substance alone or by dissolving and dispersing it together with the above-mentioned binder resin.

In this case, when a carrier transport substance is contained in the carrier generation layer, the carrier transport substance is dissolved or dispersed in the solution (a) or the dispersion liquid (b) in advance, that is, in the carrier generation layer. There is a method of adding a carrier transport substance. In this case, it is preferable that the amount of the carrier transport substance added is within the range of 1 to 100 parts by weight per 100 parts by weight of the binder. Alternatively, there is a method in which a solution containing a carrier transport substance is applied onto the carrier generation layer, and the carrier generation layer is lubricated or partially dissolved to diffuse the carrier generation substance into the carrier generation layer. When this method is adopted, it is not necessary to add a carrier transporting substance to the carrier generation layer as described above, but it is also possible to carry out the above three methods at the same time.

As the solvent or dispersion medium used for forming the layer, n
-butylamine, diethylamine, ethylenediamine,
Isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone,
Hensen, toluene, xylene, chloroform, 1.2
- Dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide and the like.

The photosensitive layer, undercoat layer, intermediate layer, protective layer, etc. can be provided by, for example, blade coating, dip coating, spray coating, roll coating, spiral coating, or the like.

The conductive substrate is made of paper by coating, vapor deposition, laminating, etc. a conductive thin layer made of a metal plate, a metal drum, or a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold. , a material provided on a substrate such as a plastic film is used.

Next, preferred embodiments of the present invention will be explained.

FIG. 2 is a schematic diagram of the configuration of an example of a recording device that implements the method of the present invention, FIG. 3 is a diagram of a schematic configuration of a laser beam scanner for image exposure, and FIG. 4 is a partial cross-section diagram of an example of a developing device. Figure 5 shows the implementation flowchart 1 of the method of the present invention.
It is.

In the apparatus shown in FIG. 2, 23 is a drum-shaped image carrier which has a photosensitive layer made of the above-mentioned organic photoconductive substance and rotates in the direction of the arrow; 22 is a main charger that uniformly charges the surface of the image carrier 23; 24 is an image exposure device, and 15 is a developing device. 20 is a pre-transfer exposure lamp provided as necessary to facilitate the transfer of the toner image formed on the image carrier 23 onto the recording medium P; 21 is a transfer device; 19 is a separation corona discharger; 12
is a fixing device that fixes the toner image transferred to the recording medium P. 13 is a static eliminator consisting of one or a combination of a static elimination lamp and a corona discharger for static elimination; 14 is an image carrier 2;
This cleaning device has a cleaning blade and a fur brush for removing residual toner on the surface after transferring the image No. 3.

When the image exposure is performed using a semiconductor laser, in the case of a recording device that uses a drum-shaped image carrier 23 like the recording device shown in FIG. 2, the image exposure 24 is performed using a laser beam scanner as shown in FIG. 3. Preferably.

The operation of the laser beam scanner shown in FIG. 3 will be described next.

The laser beam generated by the semiconductor laser 41 is rotated and scanned by a polygon mirror 43 rotated by a drive motor 42 , passes through an f-theta lens 44 , has its optical path bent by a reflecting mirror 45 , and is directed onto the surface of the image carrier 23 . It is projected to form a bright line 46.

47 is an index sensor for detecting the start of beam scanning, and 48 and 49 are cylindrical lenses for correcting the inclination angle. Reflecting mirrors 50a, 50b, and 50c form a beam scanning optical path and a beam detection optical path.

When scanning is started, the beam is detected by the index sensor 47, and modulation of the beam by a signal is started by a modulation section (not shown). The modulated beam is applied to an image carrier 23 that is uniformly charged in advance by a charger 22.
Scan above. A latent image is formed on the drum surface by the main scanning by the laser beam 51 and the sub-scanning by the rotation of the image carrier 23.

Further, in a recording apparatus in which the image carrier can take a flat state such as a belt shape, the image exposure can be a flash exposure.

As the developing device 15, one having a structure as shown in FIG. 4 is preferably used. In FIG. 4, the developer De is conveyed in the direction of arrow G as the magnetic roll 62 rotates in the direction of arrow F and the sleeve 61 rotates in the direction of arrow G. Developer D
e is the thickness t due to the spike control blade 63 during conveyance.
is regulated.

The spike control blade 63 presses the surface of the sleeve 61 made of an elastic metal plate to control the thickness of the developer being conveyed. A stirring screw 65 is provided in the developer reservoir 66 to sufficiently stir the developer De, and when the developer De in the developer reservoir 66 is consumed, the toner supply roller 68 rotates. As a result, toner T is replenished from the toner hopper 67. A DC power supply 69 that applies a developing bias to the sleeve 61 and a protective resistor 70 are connected in series. In addition, the sleeve 61 and the image carrier 23
are arranged opposite to each other with a gap d in between, and the developer contacts the image carrier 23 in the development area E, so that t>d. At this time, development may be performed under non-contact conditions (t<d).

In the figure, the developing sleeve 61 and the magnet body 62 are indicated by the arrow G-
Although it is shown that the developing sleeve 61 rotates in the F direction, even if the developing sleeve 61 is fixed, the magnet body 62 is fixed, or the developing sleeve 61 and the magnet body 62 rotate in the same direction. It may be something. When the magnet body 62 is fixed, normally, in order to make the magnetic flux position of the magnetic pole facing the image carrier 23 larger than the magnetic flux density of the other magnetic poles, the magnetization is strengthened or a magnet with the same or different polarity is placed there. A number of magnetic poles may be provided close to each other.

In the above-mentioned apparatus, based on the present invention, the electrostatic latent image is charged so that the IVHl is 400 to 900 ■,
F”) During reversal development (DIVsl IV-CI= O~
200'V. However, VDt is a direct current bias voltage applied to the sleeve 61 as a developer transport carrier facing the image carrier 23.

It is preferable to superimpose an AC bias voltage on the DC bias voltage. At this time, the effective value of the AC bias voltage is 0.
5 to 4 kV is preferable, and the frequency is 0.1 to 7 IMHz
is preferred.

The method of the present invention as shown in FIG. 5 can be carried out using the recording apparatus as described above.

Figure 5 shows that an electrostatic image is formed by an electrostatic image forming method in which the exposed part of the image becomes an electrostatic image with a lower potential than the background part, and during development the electrostatic image is charged to the same polarity as the potential of the foreground part. □ Shows an example of reversal development of the present invention performed by toner deposition.

The example shown in FIG. 5 when the recording position i shown in FIG. 2 is used will be explained.

First, the static electricity is removed by the static eliminator 13, and the cleaning device 14
The surface of the image carrier 23 in the initial state, which has been cleaned with a voltage of 0, is uniformly charged by the charger 22, and the image exposure 24 is projected onto the charged surface to form an electrostatic image area. Image exposure is performed such that the potential of the toner becomes approximately O, and the obtained electrostatic image is developed by a developing device 15 (toner T).

The image forming method of the present invention can be applied to various light sources such as halogen lamps, tungsten lamps, LEDs (light emitting diodes), gas lasers such as helium-neon, argon, and helium-cadmium, and semiconductor lasers.

The image forming method of the present invention has a wide variety of applications such as electrophotographic copying machines and printers.

E9 Examples The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited thereby, and of course includes other embodiments with various modifications.

<Evaluation of coatability of carrier generation layer> (Example 1) First, a charge blocking layer or an undercoat layer was formed as follows.

For charge blocking layers or undercoat layers obtained by adding 30 g of the substances shown in Table 1 to a solution of 100 g of the specified binder resin shown in Table 1 dissolved in 1000 ml of the specified solvent and dispersing the mixture in a ball mill for 24 hours. Using the coating liquid, laser printer rLips-10J (manufactured by Konica)
A charge blocking layer or undercoat layer having a thickness of about 2 μm was formed by dip coating onto a raw aluminum pipe (diameter 60 mm).

Next, 10 g of carrier generating substance (CGM) shown in Table 1
After grinding in a ball mill at 20 rpm for 15 hours,
Polycarbonate resin “Panlite L-1250J (
(manufactured by Kijin Kasei Co., Ltd.) 20g to 1,2-dichloroethane 101
Add a solution dissolved in 00O and disperse for another 200 hours, and dip coat the obtained carrier generation layer coating solution onto the charge blocking layer or undercoat layer to form a carrier generation layer, and then apply the carrier generation layer. The gender was evaluated.

Regarding the good/bad coating properties of the carrier generation layer, the relative effective speed (c/s) of the coating liquid level during dip coating of the carrier generation layer was set to 0.5 cm/sec and 1.0 cm/sec.
cm/sec, 100 cf (ldm2) when applying the carrier generation layer at 1.5 cm/sec
The amount of CCL applied per unit was measured and this value was 2111g/
If it was less than dm2, it was determined that the coating was defective. Regarding aggregation of the carrier generation layer, presence or absence of density unevenness in the carrier generation layer was visually confirmed, and if aggregation was observed, the coating was judged to be defective.

The results are shown in Table-1.

Table-1 (blank below) tζQ-binder (X) Polyvinyl butyral resin rXYHL (manufactured by Union Carbide) Binder (Y) Polyvinyl 7 pachiral resin “S-LEC BH-3”
(Manufactured by Block Chemical Co., Ltd.) Binder (Z) Polyvinyl formal resin “Denka Formal #30J
(manufactured by Denki Kagaku Kogyo Co., Ltd.) Binder (S) Polyester resin "Vylon 200 J (manufactured by Toyobo Co., Ltd.) Binder (T) Vinyl chloride-vinyl acetate copolymer resin rVYHHJ
(manufactured by Union Carbide) (χ): Tetrahydrofuran (t): Acetone-cyclohexanone (4:1) mixed solvent (s): 1,2-dichloroethane CGM (1) CG M (2) CG M (3) CG M (4) As shown in Table 1, resins (X), (Y), and (Z) having substituted or unsubstituted vinylphenol structural units are contained in the charge bronking layer or undercoat layer, and When a carrier generation layer containing the carrier generation substances (1), (2), and (3) of the present invention is coated on the above layer,
The amount of CGL applied is also good, and no agglomeration of CGM occurs. On the other hand, resin (S), (
When T) or the carrier-generating substance (4) was used, the coating properties were poor.

<Production of Photoconductor> Photoconductor A-1 of Example and photoconductor a-r of Comparative Example were produced in the following manner.

In the same manner as described in the section <Evaluation of coatability of carrier generation layer>, a charge bronking layer or an undercoat layer was formed on a conductive substrate, and a carrier generation layer was further formed. The formulation of each layer is as shown in Table 2 below, and photoreceptor A-1 is as shown in Table 2 below.
Corresponding to coating examples A to ■ of 1, photoreceptors a to 0 are coated with coating examples a to
Corresponds to 0.

However, c/s (relative drop rate of the liquid level during dipping application) was adjusted so that the amount of CG LO applied was 2±0.1 mg/dm2. At this time, for coating examples g, h, and 1,
In Table 1, since it was not possible to ensure a CGL coating amount of 2 mg/dm 2 or more, it was excluded from the target of photoreceptor production.

In addition, we have newly introduced an example in which silicon oxide is contained in the undercoat layer (
For the photoreceptors p, q, and r), an undercoat layer and a carrier generation layer were formed in the same manner as described above.

Furthermore, a carrier transport material obtained by dissolving 100 g of a carrier transport substance of the following structural formula (5) and 200 g of polycarbonate-1 resin [Niepilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Ltd.) in 1000 mff of 1,2-dichloroethane A layer coating solution was applied by dipping onto the carrier generation layer, and the temperature was 8.
It was dried at 5° C. for 1.5 hours to form a carrier transport layer with a thickness of about 25 μm, thereby producing a photoreceptor according to the present invention and a comparative photoreceptor.

Table 2 shows the formulation of each photoreceptor.

C no, /27 go zu ε〉92n table -2 (ω) Hθ resistance element <Image evaluation (1)> (Example 2) Each of the photoreceptors A to ■ and a'-r was exposed to a semiconductor laser (wavelength 780 nm, output 2 mW) as a light source
Installed on a modified y-printer N-1ps-10 (manufactured by Konica), adjusted the grid so that '117H was -550±10 (Vl), and then set the developing bias DC-450.
(V) -1-AC700 (Vll (2kHz)) was applied to perform reversal development under non-contact conditions, and the resulting image was evaluated for black spots in the white background area, moiré in the halftone area, and image density in the black background area.

For evaluation of black spots, the particle size and number of black spots are measured using an image analysis device "Omnicon 3000" (manufactured by Takasu Seisakusho Co., Ltd.), and the number of black spots with a diameter of 0.05 or more is determined per 1 cm. Judgment was made based on how many there were. The criteria for black spot evaluation are as shown in Table 3.

Table 3 Moire is evaluated visually for the presence or absence of moire in the halftone dot area with a black ground area ratio of 30%, and ○ indicates that there is no moire.
× indicates the occurrence of moiré.

The results of image evaluation for each photoreceptor are shown in Table 4 below.

Table 4 As shown in Table 4, according to the method of the present invention, satisfactory results were obtained in terms of black spots, moiré, and image density. In contrast, photoreceptors a-f for comparison (contents in undercoat layer: conductive T)
iO2, carbon black), no potential was applied and image evaluation could not be performed in any case. Furthermore, when comparative photoreceptors jo to o (with CGM aggregation) were used, black spots occurred in all of them. Furthermore, a comparative photoreceptor p −
When r is used, due to the blocking effect of the undercoat layer,
Although good results were obtained for black spots, the image density decreased due to low sensitivity.

<Image evaluation (2)> (Example 3) Reverse development was performed under the conditions shown in Table 5 below, and the black spots, image density of black background parts, and fog in the copied image were observed.

(Hereafter, margin) Table-5 (69n From the above, the following is clear.

When 1VHl<400V, the image density is insufficient.

IVHI IVp (1>200 V T: L! Cuff' !7 Occurrence (reverse polarity) fog due to toner adhesion).

IVHl 1 Vocl < O carbon also causes fogging (normal fogging).

<Image evaluation (3)> (Example 4) Photoreceptor A was mounted on the rLips-10J modified machine, and 1
We conducted a long-run test of 10,000 cycles each at 0°C, 220% low temperature, low humidity, and 30"C, 80% high temperature and high humidity, and the results showed that there were no black spots, moire, fog, etc. in either environment. An image with stable density was obtained.The image forming conditions were as follows.

Grid voltage knee: 500 [V] Total charging current: 0.5 mA Developing high speed: DC-450 (V: l + AC70
0 (V) (set to 2) Development: Non-contact component magnetic brush development When an image was formed on the photoreceptor P under similar conditions, the image density was low from the beginning and moiré occurred, so a long run of 10,000 cycles was required. The test could not be conducted.

[Brief explanation of the drawing]

1 to 5 show embodiments of the present invention. FIG. 1 is a cross-sectional view of each photoreceptor used in the present invention, a schematic diagram of its construction, and FIG. 4 is a developing device. FIG. 5 is a sectional view of the main part, and is a flowchart showing the process of image formation. FIG. 6 is a partial sectional view of a conventionally used photoreceptor. FIG. 7 is a partial cross-sectional view of a photoreceptor for explaining the cause of moiré. In addition, in the symbols shown in the drawings, 1... Conductive substrate 4... Carrier transport layer 6... Carrier generation layer 7...・・・・・・・・・1Kobe Pro, Su>g layer 8...
......Photosensitive layer 12...Fuser 13...Static eliminator 14...Cleaning device 15...
...Developer 20...Pre-transfer exposure lamp 21...
...Transfer device 22...Charger 23...Image carrier 41...Laser 43... ...Mirror scanner 44...
...F-θ lens for imaging 48.49...
...Cylindrical lens 51...Laser beam 61...Developing sleeve 62...Magnet 63... Layer thickness regulation blade 69...
. . . Bias power supply 70 . . . Protection resistor.

Claims (1)

[Scope of Claims] 1. In an image forming method using a photoreceptor having a photosensitive layer having a carrier transport layer provided on a carrier generation layer, (a) a compound represented by the following general formula [I] in the molecule: a carrier generating layer containing as a carrier generating substance a compound having a coupler and having at least two azo groups in the molecule; (b) using a photoreceptor having a charge blocking layer containing titanium oxide and provided between the carrier generation layer and the conductive substrate; ~9
After applying a charge of 00 V, an electrostatic latent image is formed by exposure, and then the voltage is 0 to 200 V lower than the absolute value of the charged potential.
An image forming method characterized in that reversal development of the electrostatic latent image is performed by applying a DC bias voltage having a low absolute value of V. General formula [I]: ▲ Numerical formulas, chemical formulas, tables, etc. represents an alkyl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkoxy group, s represents 0-4, and r represents 0-2. ]