JPH01303445A - Photosensitive body and image forming method - Google Patents

Abstract

PURPOSE:To obtain a good image free from defects such as black spots by successively laminating a carrier generating layer containing a specified compound as a carrier generating material and a carrier transfer layer on a charge blocking layer containing an organic pigment and a novolak type phenol resin. CONSTITUTION:The photosensitive body is formed by successively laminating the carrier generating layer containing the compound having the coupler residue represented by formula I and at least 2 azo groups in the molecule as the carrier generating material on the charge blocking layer containing the organic pigment and the novolak type phenol resin, thus permitting the blocking layer provided between the substrate and the carrier generating layer to form a barrier against local injection of carriers from the side of a conductive substrate, disappearance and decay of surface potential due to local carrier injection to be hindered, black spots on an image caused by reversal development to be prevented, and a defect-free high-quality image to be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoconductor and an image forming method using the photoconductor, and particularly relates to an electrophotographic photoconductor and an electronic photoconductor using the photoconductor. It relates to a photocopying method.

[Prior Art] In the electrophotographic copying method of the 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 not only has electrophotographic properties such as good charging characteristics, good sensitivity, and low dark decay, but also has good printing durability after repeated use, 1f abrasion resistance, moisture resistance, etc. It is also required to have good physical properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance).

2. Description of the Related Art Hitherto, as an electrophotographic photoreceptor, a blind photoreceptor having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide has 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-t-linitro9-
An organic photoreceptor having a photosensitive layer containing fluorenone is described. 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 great durability by assigning the carrier generation function and carrier transport function to different substances in the photosensitive layer. being done. In such so-called functionally separated electrophotographic photoreceptors, materials that exhibit each function can be selected from a wide range of materials, making it relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. It is possible to do so. 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 2 and a carrier transport layer 3 are sequentially laminated on a conductive substrate 1, and is used for negative charging. That is, the photosensitive layer 4 is composed of a carrier generation layer 2 and a carrier transport layer 3.

In the electrophotographic photoreceptor having the above-mentioned layer structure, when the square band type is used, the mobility of holes is higher than that of electrons, so it is possible to use a hole transporting photoconductive material with 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.

[Problems to be Solved by the Invention] However, in the photoreceptor as described above, carrier injection from the conductive body or lower layer side tends to occur when negatively charged, as shown in FIG. The charge disappears or decreases microscopically. Although the cause of such local carrier injection is not clear, it is thought to be caused by defects or non-uniformity on the surface of the conductive enclosure, non-uniformity in the charge generation layer, or the like.

Such local carrier injection causes the following problems.

Recently, for example, printers that involve digital processing are
5, reversal development is often adopted, but in the reversal development method, the exposed area (portion where surface charge has disappeared, VL)
A toner image is formed on the surface, and no toner image is formed on the unexposed area (portion where surface charge is retained, VH).

However, in the reversal development method, if 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 will appear in that area, causing so-called fog. It becomes an image. This kind of fog is different from normal fog, and is a phenomenon that occurs when the main surface of the photoreceptor microscopically disappears or decreases during the reversal phenomenon as shown in the book above, and is called "black body". being called. These black spots are localized toner particles on a white background, so they are much more noticeable than when the black background is white, and they significantly reduce the quality of the image, resulting in an unsuitable image. It is a defect.

As a way to solve these problems, carrier transport layer 3
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 attempts to reduce the hole transport ability of the carrier transport layer 3 and suppress carrier injection into the photoreceptor surface l\, but in this photoreceptor, the photosensitivity decreases, the residual potential increases, Increase in IVLI, IVLI during repeated use
This results in a decrease in stability and a decrease in temperature characteristics, and at low temperatures, photoreceptor characteristics such as the upper limit of IVLI change significantly.

On the other hand, in FIG. 6, it is also conceivable to provide a charge blocking layer between the carrier generation layer 2 and the conductive substrate 1 to block carrier injection from the conductive substrate 1. However, in this case, the transport of photocarriers that occurs even during light exposure is suppressed and blocked by the blocking layer, and the residual potential increases during repeated use, resulting in an image 1 shortage of 10 <.

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 2 on such a charge blocking layer, depending on the type of the carrier generation layer, the carrier generation substance may aggregate, resulting in poor coating, resulting in an increase in black spots, a decrease in image density, and even This also resulted in image unevenness, which caused serious inconvenience.

On the other hand, as a countermeasure from a process perspective, it is possible to increase the difference between the charging potential VH and the bias voltage Voc, but this does not make the difference between the potential VL of the exposed area and the bias voltage VDC
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-Affi-As) is widely used in semiconductor lasers.
) type light emitting device has an oscillation wavelength of about 75001 or more. 1q of electrophotographic photoreceptors sensitive to such long wavelength light.
Many studies have been carried out to date. for example,
A method of adding a 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 has been considered, but selenium and cadmium sulfide have poor resistance to temperature, humidity, etc. There are problems in practical use due to insufficient IM resistance and toxicity. In addition, the sensitivity of many known organic photoconductive materials is usually limited to the visible light region of 700 na+ or less, and there are few materials that have sufficient sensitivity in longer wavelength regions. It has been difficult to use this method in laser printers that use semiconductor laser light sources.

The technical system using such a laser beam etc. is expected to be applied to blinking, and this is why it is desired that a useful image forming method by reversal development be developed.

The purpose of the present invention is to solve the following problems in reversal development where black body is likely to occur.
It is possible to obtain good images without image defects such as black spots, and it is possible to obtain high-quality images with no fog and high image density even in environments such as high temperature and high humidity, low temperature and low humidity, and even when used repeatedly. Another object of the present invention is to provide a photoreceptor that can stably supply a uniform image with high image density, and an image forming method using the photoreceptor.

Means for Solving Problem E] The present invention has a coupler represented by the following Funato [A] in the molecule on a charge blocking layer containing an Akebono pigment and a novolac type phenolic resin, and at least 2
The present invention relates to a photoreceptor characterized in that a carrier generation layer and a carrier transport layer containing a compound having azo groups in the molecule as a carrier generation substance are successively provided.

- Shipman [Δ] In the formula, ArI represents an aryl group, and Y and 7 are each a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted It represents an alkoxy group, S represents 0-4, and r represents 0-2.

Furthermore, 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, in which: (a) a coupler represented by the following - Shipman [A] in the molecule; and a carrier-generating layer containing a compound having at least two azo groups in its molecule as a carrier-generating substance; and a carrier-generating layer containing a novolac type phenolic resin and an organic pigment, the carrier-generating layer and a conductive substrate. (b) using a photoreceptor having a charge blocking layer provided between the photoreceptor;
After imparting a charge of V~900V, an electrostatic latent image is formed by exposure, and then the absolute value of the charged potential is 0~900V.
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 an absolute value lower than 200V.

- Shipman [A] In the formula, A "1 represents an aryl group, and Y and Z each represent a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted amine group, or a substituted or unsubstituted amine group. represents a substituted alkoxy group, S represents 0 to 4, and `` represents 0 to 2. However, the charging potential and the DC bias voltage have the same sign.

[Operations and Effects] In the present invention, a compound having a coupler represented by the above-mentioned shipman [A] in its molecule and at least two azo groups (hereinafter referred to as a specific azo group) is used as a carrier generating substance. It has a remarkable feature in that it contains a compound (referred to as a compound) in the carrier generation layer, and the material and content of the charge blocking layer provided between the carrier generation layer and the conductive substrate 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 an old law.

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 2 and reach the surface of the photoreceptor via the carrier transport layer 3 having high hole transport properties. In other words, the carrier generation layer 2 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 of obtaining a high quality image free of image defects can be achieved.

It is thought that the reason why the charge blocking layer can 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 substance and the organic layer II. can be said to be 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 This is extremely inconvenient because it causes agglomeration and poor coating, a significant increase in black spots, a decrease in photosensitivity, and even unevenness of the image.

However, there is no general or uniform selection method for selecting a suitable combination that will not cause coating defects from among the countless existing polymeric materials and numerous carrier-generating substances; The reality is that we have no choice but to decide on a good combination based on the stacking margin.

As a result of various studies, the present inventors have found that extremely good results can be obtained by particularly selecting a combination of the above-mentioned specific azo compound and novolac type phenolic resin.

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. Furthermore, since this particular azo compound has high sensitivity in a long wavelength region, it is possible to provide a high-performance photoreceptor that is particularly suited to an image forming method by reversal development using a semiconductor laser as a light source.

In addition, by containing a novolak type phenolic resin in the charge blocking layer, the above-mentioned specific azo compound does not aggregate during coating formation of the carrier generation layer.
Therefore, black spots and image unevenness can be prevented during the reversal process, and the specific azo compound can be uniformly dispersed in the carrier generation layer, allowing the specific azo compound to exhibit its original photosensitivity 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 contents.This allows us to solve the technical problem of preventing black spots, which is essential for reversal development, as well as to improve temperature and humidity characteristics. It is attracting attention because it has excellent environmental resistance properties and 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 printers such as printers are used for long periods of time under various conditions, there are many opportunities for them to be exposed to environments such as high temperature and humidity, low temperature and low humidity, and they are good even at low temperatures. This is because there is a demand for providing images that are accurate.

In this regard, in the present invention, negative photocarriers generated within the carrier generation layer during light irradiation are presumably transported within the charge blocking layer by the organic pigment and transferred to the conductive substrate. That is, it is considered that the charge blocking layer was given electronic conductivity by the action of the organic pigment. Therefore, the movement of photocarriers becomes smooth, making it possible to increase photosensitivity, reduce residual potential during repeated use, and increase image quality. 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. Moreover, even under high temperature and high humidity, the carrier generation layer is 1! l! Therefore, the increase in dark attenuation can be suppressed and no fogging will occur.

Moreover, by incorporating an organic pigment into the charge blocking layer, the height resistance of the layer can be maintained.
If a conductive inorganic substance or the like is used, carrier injection cannot be prevented, black spots will appear on the image, and the charge blocking function will not be exhibited.

Furthermore, what should be noted in the uniformity forming method of the present invention, in addition to the above, is that the absolute field of the charging potential represented by IVHI mentioned above is limited to a specific range of IVHI = 400V to 900V. Therefore, the results described above will not occur. That is, when IVHI<400V, it is difficult to obtain the required electric field strength, but when IVHI>90
If the voltage is set to 0V, the thickness of the photosensitive layer becomes large for this purpose.
This reduces sensitivity, which is undesirable. In addition, in the image forming method of the present invention, lVHl-1 Vocl, which is the difference between IVHI and IV,ol (absolute value of DC bias voltage)
It is also important that the voltage is specified as 0 to 200V.

That is, if l VHI l VDC1 <ov, fogging will occur, and if IVHIIVDC1>
In the case of 200V, carrier adhesion (when using a two-component developer) or adhesion of opposite polarity toner (when using a bipolar-component developer)
will occur.

Therefore, in the image forming method of the present invention, 1VH1=4
00 to 900V (preferably 500 to 700V), V) l l l VDr, l = C) to 200
By performing reversal development under the condition of V (preferably 50 to 150 V), it is possible to obtain a good image with high image quality and no black spots while maintaining high sensitivity.

When the present invention is applied to a reversal development method, when applied to a printer in 11, the character area (black background area) is smaller in 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 images by using a photoreceptor as shown in Figure 6 and irradiating semiconductor laser light, it is difficult to obtain a solid image. Interference fringe-like 'a' called moire
It was causing unevenness.

Therefore, there has been a demand for a 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 number of 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 interference fringe-like density unevenness on images is not clear, but it is thought to be similar to the old method.

As shown in FIG. 7, when the surface of the photoreceptor shown in FIG.
The light is reflected by the surface 3a of the substrate and becomes reflected light 7, and a part of the light enters the photosensitive layer 4 and is reflected by the substrate surface 1a to be emitted as emitted light 8. At this time, the refractive index of the photosensitive layer is 0, the thickness d,
Assuming that the wavelength of the semiconductor laser light is λ and that the laser light is incident perpendicularly to the photosensitive layer 4, an optical path difference of (2nd−λ/2) occurs between the light 7 and the light 8. Since the laser light is coherent, interference occurs between the light 7 and the light 8, 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 3. The intensity of light is minimal (according to the law of conservation of energy), nd is λ
When the value is an odd multiple of /4, the anti-light is at a minimum, that is, the light entering the interior is at a maximum. By the way, due to manufacturing reasons, d has an unavoidable location unevenness of 1 μmV1 degree. Since the laser beam has good monochromaticity and is coherent, the above-mentioned interference conditions change in response to the unevenness in the location of d, causing unevenness in the location where the laser light is absorbed most in the carrier generation layer 2, which causes the peta image to be It is thought that the density becomes uneven in the form of interference fringes.

Note that in normal copying, since the light source is not monochromatic light, the width 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 the amorphous pigment. A large portion of the light is scattered into the charge blocking layer due to the dispersion state of the charge blocking layer. With this machine,
It is thought that interference will no longer occur, and local unevenness in the intensity of reflected light due to interference will also no longer occur.

[Specific Structure of Explanation] FIG. 1 illustrates a general structure of a photoreceptor, for example, an electrophotographic photoreceptor, used in the present invention.

In the photoreceptor shown in FIG. 1, a carrier generation layer 2 is provided on a conductive substrate 1 with a charge blocking layer 5 interposed therebetween.
A carrier transport layer 3 is provided on the carrier generation layer 2. 4 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.

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

This is a compound that contains the coupler represented by the above-mentioned -Funenin [A] in its molecule and has at least two azo groups in its molecule.

Specifically, 21 [! A disazo compound having If, a trisazo compound having three azo groups,
Some have four or more azo groups.

Examples of the disazo compound include those shown in Shipin [B] below.

General formula [B]: Cp-N=N-D-N=N-Cp Here, as D, for example, H2 CN CN In addition, as other azo compounds, the following - Boatman% formula % - Boatman [ C]2Ar” N=N-Cp General formula (DC Cp-N=N-Ar2-N=N-Ar3-N=N-Cp
-Sailor [E]: Cp-N=N-Ar”-N=N-Ar3-N=N-Ar
4--N=N-CP However, Ar2, Δ'3 and Ar4 each represent a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group.

Ar 2 , Ar 3 , Ar 4 U) Specific examples include: Examples of Go (coupler) include the following.

CP i; cp-n: Here, Ar' is, for example.
It can be easily synthesized according to the method described in No.

Next, the novolak type phenolic resin will be described.

This is obtained by reacting phenols and aldehydes under an acidic catalyst.

Examples of phenols include phenol, I-cresol,
Examples of the aldehydes include O-cresol, p-cresol, xylenol, and resorcinol, and examples of aldehydes include formaldehyde, acetaldehyde, and furfural.

Note that the term phenol resin here is a general term that also includes phenol-modified resins.

Specific product names include 5K-1, 2, 3, 4, 5, 6.
,7,8,9,io,iol,102.103.104
．． 105.106.107.108.109.110.
111.112.113.114.115.136.1
37.156.158.159 (manufactured by Sumitomo Schless), and the like.

Examples of organic pigments used in the present invention include red (
400~500nm), green (500~6QQnm
), blue (600 to 700 nm), etc., have high transmittance for each color, are heat resistant, and do not cause bleeding.

Examples of blue organic pigments include ε-type copper phthalocyanine blue and Victoria Blue Lake (C, I, P
igment Blue 1) as the main component, and methyl violet lake (C, 1, P
igment Violet 3) and dioxazine violet (C,[,Picu+entviol
Examples include those using one or two of et 1 ) as a spectral property adjusting agent. Note that ε-type copper phthalocyanine blue is a clear blue pigment with a strong reddish tinge, which is known from Japanese Patent Application Laid-Open No. 52-6301, etc.
M, trade name).

The spectral characteristics (visible absorption spectra) of the most commonly used phthalocyanine pigments in various crystal forms such as α and β are that their dominant wavelength is 490 to 500 rv, while ε type steel phthalocyanine blue has a wavelength on the shorter wavelength side of 470 to 480 nm. ,
Furthermore, the dominant wavelength of Victoria Blue Lake is 430 nm.

Further, as a red organic pigment, for example, a naphthol-based orange pigment (C, 1, Pigment Oranoe24)
, pyrazolone orange pigment (C, I.

Pigment Qrange l 3. 1) and disazo orange pigment (C, [, Pigment O
The main component is one or more selected from range 13), and if necessary, a naphthol-based red pigment (C
, [.

pigment Red 22, 8. Same 5.
Same 4. 3゜31. Same 112. 114) and pyran-based red pigments (C, I, P luent R
Examples include those using one or more selected from ed3B) as a spectral property adjusting agent.

In addition, examples of green pigments include polychloropolybromophthalocyanine green (C, [.

Pigment Green 38) is the main component, and disazo yellow pigments (C9l, Pigment Green 38) are the main ingredients.
nt Yellow 12゜Same 13. 14) and isoindolinone yellow pigments (C, I, pigme
Examples include those using one or more selected from the group of nt Yellow 109 and nt Yellow 100) as a spectral property adjusting agent. Polychlorophthalocyanine green (C, I,
P 1uent Green37) has a dominant wavelength of si
onm, while that of polychloropolybromophthalocyanine green is located at 535net.

The thickness of the charge blocking layer is preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm. In addition, in the charge blocking layer, the content ratio (monomerization) of the organic pigment and the binder substance is t (1:1).
The ratio is preferably within the range of 0) to (10:1).

In the carrier generation layer, the content ratio of the carrier generation substance to the binder substance is preferably 371 to 1/10, more preferably 2/1 to 1/3.

The thickness of the carrier generation layer is preferably 0.1 μm or more, more preferably 0.2 to 5 (1 m).

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 low due to the thinness, and the printing durability 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.

Further, in the carrier transport layer, the carrier transport substance preferably has excellent compatibility with the binder substance. As a result, turbidity and opacity do not occur even if the binder substance is added to the binder substance, allowing for a very wide mixing ratio with the binder substance.Also, due to its excellent compatibility, charge generation 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 repeated transfer type 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 14% azo compound. 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, Axazole derivatives, oxadiazole derivatives,
Thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives,
imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives,
Oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, poly-N-vinylcarbazole, poly-1- vinylpyrene, poly-9
- One or more types selected from vinylan 1-helix and the like may be used.

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 [I] or [,I
] Styryl compounds can be used.

-Funenin [■Koni (However, in this -Funenin, R1, R2: represents a substituted or unsubstituted alkyl group, aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amine group, a hydroxyl group, and a halogen atom. , using an aryl group.

A"1. Ar2: represents a substituted or unsubstituted aryl group, and as a substituent, an alkyl group, an alkoxy group, a substituted amine 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 used include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an aryl group. ) General formula [■]: (In this general formula, R5: substituted or unsubstituted aryl group, R6, hydrogen atom, halogen atom, substituted or unsubstituted alkyl group,
Does not represent an alkoxy group, an amino group, a substituted amine group, a hydroxyl group, R7, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. ) Also, a hydrazone compound of the following general formula % formula % [ ] can also be used as a carrier transport substance. General formula [■]: (However, in this general formula, R8 and R9 are each a hydrogen atom or a halogen atom, R10 and R11: each represents a substituted or unsubstituted aryl group, Ar3: represents a substituted or unsubstituted arylene group.) General formula [IV]: (However, in this general formula, R12: a substituted or unsubstituted aryl group, a substituted or represents an unsubstituted carbazolyl group, or a substituted or unsubstituted heterocyclic group; R13, R1 and R15: represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group ) General formula [IVa]: R'? (However, in this general formula, R16: methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R17: methyl group, ethyl L (, benzyl group or phenyl group, R18: methyl group, ethyl group, General formula [IVbl] (representing a benzyl group or a [technyl group]): (In which general formula, R19 is a substituted or unsubstituted naphthyl W: R20 is a substituted or unsubstituted alkyl group, aralkyl group, or aryl m , R21 is a hydrogen atom, an alkyl group or alkoxy14, R22 and R
23 represents groups that are the same or different from each other and are each composed of a substituted or unsubstituted alkyl group, aralkyl group, or aryl group. ) General formula [vl: (However, in this general formula, R24: substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R25: hydrogen atom, @substituted or unsubstituted alkyl group, or substituted or unsubstituted Substituted aryl group, Q: hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group, or cyano group, S: does not represent an integer of 0 or 1.) In addition, as a carrier transport substance, the following general formula [ Vl]
hydrazone compounds can also be used.

General formula [VI]: (However, in this general formula, y: 0 or 1, R26 and R27: substituted or unsubstituted aryl group, R28: substituted or unsubstituted aryl group, or heterocyclic group, R29 and R30 : Hydrogen atom, alkyl group having 1 to 4 carbon atoms, or substituted or unsubstituted aryl group or aralkyl group (However, both R29 and R30 are not hydrogen atoms, and when y is O, R29 is not a hydrogen atom.) 1 Furthermore, amine derivatives of the following general formula [Vl] can also be used as the V-rea transport material.

General formula [■]: Ar' \ (However, in this form, Ar4.Ar5 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.

Ar6: represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group, heterocyclic group,
As the substituent, an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group, an aryl group, an amino group, a di-i-ro group, a piperidino group, a morpholino group, a naphthyl group, an anthryl group, and a substituted amine group are used. However, an acyl group, an alkyl group, an aryl group, or an aralkyl group is used as a substituent for the substituted amino group. ) Furthermore, a compound of the following general formula [■] can also be used as a carrier transport substance.

General formula [■]: (However, in this form, A r 7 represents a substituted or unsubstituted arylene group, Rat , R32, R33 and R31: substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, or an N-substituted or unsubstituted aralkyl group.) Furthermore, a compound of the following general formula [IX] can also be used as a carrier transport substance.

General formula [■]: (However, in this form, R35, R36, R37 and R3
8 is a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group,
A benzyl group or an aralkyl group, R39 and R40 each have a hydrogen atom, substituted or unsubstituted carbon atom number of 1 to
40 alkyl groups, cycloalkyl groups, alkenyl groups,
Cycloalkenyl group, aryl group or aralkyl group (provided that R39 and R40 jointly represent carbon atoms rlI3-10
may form a saturated or unsaturated hydrocarbon ring.

) R41, R42, R43 and R44 are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group,
Aryl group, aralkyl group, alkoxy group, amino group,
It is an alkylamino group or an arylamine 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 can prevent an increase in residual potential and a decrease in charged potential during repeated use.

Examples of antioxidants include hindered phenols, hindered amines, paraphenylene diamines, aryl alkanes, subo-indanones and their derivatives, organic sulfur compounds, and modified phosphorus compounds.

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. 461-217492, and No. 61-221541.

A polymeric organic semiconductor can also be included in the photosensitive layer. Among these polymeric organic semiconductors, poly-N-vinylcarbazole or its derivatives are 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. .

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.

Electron-accepting substances that can be used in the photoreceptor of the present invention include:
For example, succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride,
Tetrabromo phthalic anhydride, 3-nido phthalic anhydride,
4-nido-0 phthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, m-dinitrobenzene, 1.3.5-trinitrobenzene, paranitrobenzonitrile , picryl chloride, quinone chlorimide,
Chloranil, Brumanil, 2-methylnaphthoquinone, Tsukurodisyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-
Fluorenylidene-[dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidene-[dicyanomethylenemalonodinitrile], picric acid, 0-di-
Lobenzoic acid, p-nitrobenzoic acid, 3.5-dibenzoic acid, pentafluorobenzoic acid, 5-di-salicylic acid, 3.5-dinitrosalicylic acid, phthalic acid, mellitic acid, other electronic One or more compounds having high affinity can be used. Among these, fluorenone series, quinone series, and benzene derivatives having electron-withdrawing substituents such as C2, CN, and NO2 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, stilbene compounds and derivatives thereof, triazole compounds, imidazole compounds, triazine compounds, coumarin compounds, oxadiazole compounds, thiazole compounds and derivatives thereof.

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. , addition polymer resins such as methacrylic resins, acrylic resins, polyvinylidene chloride, and polystyrene, polyaddition resins, polycondensation resins, copolymer resins containing two or more of these repeating units, vinyl chloride-acetic acid Insulating resins such as vinyl copolymer resins, styrene-butadiene copolymer resins, vinylidene chloride-acrylonitrile copolymer resins, etc.
Further examples include polymeric organic semiconductors such as N-vinylcarbazole.

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

As a binder for the protective layer provided as necessary,
Volume resistance 108Ω・ci or more, preferably 1010Ω−
A transparent resin having a resistance of 10 13 Ω-cm or more, preferably 10 13 Ω-cm or more is used. Further, the binder may be a resin that is cured by light or heat, and examples of the resin that is cured by light or heat include thermosetting acrylic resin, epoxy resin, urethane resin, urea resin, polyester resin, alkyd resin, Examples include melamine resins, photocurable cinnamic acid resins, copolymerization or condensation resins such as Kofuda et al., and all other photocurable or thermosetting resins used in electrophotographic materials. If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Examples of such thermoplastic resins include polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polycarbonate resin,
Alternatively, all of these copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials may 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.

(0) 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 molecule IlljM, an attritor, etc., and a binder is added, mixed and dispersed, and the resulting dispersion is applied.

In these methods, particles are converted into molecular Il under the action of ultrasound.
This enables uniform 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 transporting substance is contained in the carrier generating layer, a method of dissolving or dispersing the carrier transporting substance in the solution of (a) or the dispersion of (b) above, that is, the carrier generating layer There is a method of adding a carrier transport substance to the medium. 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 based on 100 small to medium parts of the binder. Alternatively, there is a method in which a solution containing a carrier transport substance is applied onto the chitria generation layer, the carrier generation layer is swollen or partially dissolved, and the carrier transport substance is diffused 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.

The solvent or dispersion medium used to form the layer is 0.
-Butylamine, diethylamine, ■dilenediamine,
Isopropanolamine, triethanolamine, triethylenediamine, N, N = dimethylformamide acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran,
Dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide and the like can be mentioned.

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 can be formed by applying a conductive thin layer made of a metal plate, a metal drum, a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold to paper by means such as coating, vapor deposition, or lamination. , a material provided on a substrate such as a plastic film is used.

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

FIG. 2 is a schematic configuration diagram showing an example of a recording device that implements the image forming method of the present invention, FIG. 3 is a schematic configuration diagram of a laser beam scanner for image exposure, and FIG. 4 is an example of a developing device. FIG. 5, a partial cross-sectional view, is a flow chart for implementing the image forming method of the present invention.

In the apparatus shown in FIG. 2, 1o is a drum-shaped image carrier that has a photosensitive layer made of the above-mentioned photoconductive material and rotates in the direction of the arrow, and 9 is a charger that uniformly charges the surface of the image carrier 1o. ,
11 is an image exposure device, and 12 is a developing device. 13 is image carrier 1
14 is a transfer device; 15 is a corona discharger for separation; 18 is a recording medium P; This is a fixing device that fixes the toner image transferred to the printer. 16 is a static eliminator consisting of one or a combination of a static eliminating lamp and a corona discharger for static elimination; 17 is a cleaning blade or a fur brush for removing residual toner on the surface of the image carrier 10 after the image has been transferred; This is a cleaning device with When image exposure is performed using a semiconductor laser, the second
In a recording apparatus using a drum-shaped image carrier 10 like the recording apparatus shown in the figure, the image exposure 11 is preferably performed by a laser beam scanner as shown in FIG.

The operation of the laser beam scanner in Figure 3 is as follows.

The laser beam generated by the semiconductor laser 19 is rotated and scanned by a polygon mirror 23 rotated by a drive motor 22, passes through an f-theta lens 24, has its optical path bent by a reflecting mirror 26, and is projected onto the surface of an image carrier 100. and form lIi'$127. 28 is an index sensor for detecting the start of beam scanning, and 20.25 is a cylindrical lens for color correction. 21812
1b.

21c is an anti-tA mirror that forms a beam scanning optical path and a beam detection optical path.

When scanning is started, the beam is detected by the index sensor 28, and modulation of the beam by a signal is started by a modulation section (not shown). The modulated beam scans over an image carrier 10 that has been uniformly charged by a charger 9 in advance. A latent image is formed on the drum surface by the main scanning by the laser beam 29 and the sub-scanning by the rotation of the image carrier 10.

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 12, one having a structure as shown in FIG. 4 is preferably used. In FIG. 4, the developer material is conveyed in the direction of arrow G as the magnet 31 rotates in the direction of arrow F and the sleeve 30 rotates in the direction of arrow G. The thickness of the developer layer is regulated by the spike control blade 32 during the conveyance. The spike control blade 32 is made of an elastic metal plate and presses against the surface of the sleeve 30 to control the thickness of the yA toner to be conveyed. A W1 screw 33 is provided in the developer reservoir 35 to ensure sufficient agitation of the developer reservoir.
When the developer in the developer reservoir 35 is consumed, toner T is replenished from the toner hopper 36 by the rotation of the toner supply roller 34. And sleeve 30
A DC current #i37 and a protective resistor 38 are connected in series to apply a developing bias. Further, the sleeve 30 and the image carrier 10 are arranged facing each other with a distance d between them, and the phenomenon agent contacts the image carrier 10 in the phenomenon region F, so that t>d. At this time, development is carried out under so-called non-contact conditions (t <
d) may be used.

In the figure, the developing sleeve 30 and the magnet body 31 are indicated by arrows G, respectively.
Although it is shown that the developing sleeve 30 rotates in the F direction, even if the developing sleeve 30 is fixed, the magnet body 31 is fixed, or the developing sleeve 30 and the magnet body 31 rotate in the same direction. It may be something. When the magnet body 31 is fixed, usually, in order to make the magnetic flux density of the magnetic pole facing the image carrier 10 larger than the magnetic flux density of other magnetic poles, the magnetization is strengthened or a magnetic pole of the same or different polarity is attached thereto. The two magnetic poles may be placed close to each other.

In the above-mentioned apparatus, based on the image forming method of the present invention, the electrostatic latent image is charged so that the IVHI is 400 to 900V, and the voltage at the time of reversal development is
Vocl = 0-200V tossle. However, L and Voc are DC bias voltages applied to the sleeve 30 as a developer transport carrier facing the image carrier 10.

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.
5-4KV is preferable, frequency is 0.1KHz-IMH
2 is preferred.

The image forming 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 image exposure area has a lower potential than the dorsal head, and development charges the electrostatic image to the same polarity as the frontal potential. 1 shows an example of reversal development of the present invention, which is carried out by the adhesion of toner.

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

First, the static electricity is removed by the static eliminator 16, and the cleaning device 17
The surface of the image carrier 10 in an initial state, which has been cleaned by the electrifier 9 and has a potential of 0, is uniformly charged by the charger 9, and an image exposure 11 is projected onto the charged surface to form an electrostatic image area. Image exposure is performed so that the potential is approximately O, and the 1q electrostatic image is developed by the carrier 12 (toner T).

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

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited thereby.

Evaluation of coating properties of carrier generation layer> (Example 1. Comparative Example 1) First, a charge blocking layer (or undercoat layer) was formed as follows.

100jl of the specified binder resin shown in Table 1 was mixed with 10ml of solvent.
Substance 30FJ shown in Table 1 is added to the solution dissolved in 00112.
Using a charge blocking layer (or undercoat layer) coating solution that was added and dispersed in a ball mill for 24 hours, dip coating was applied onto an aluminum tube (diameter 60I11m) for a laser printer rLIPs-10PLUSJ (manufactured by Konica). Then, a charge blocking layer (or undercoat layer) with a thickness of 2 μm was formed.

Next, the carrier-generating substance 20 (+) shown in Table 1 was crushed in a ball mill at 20 rpm for 15 hours, and then acrylic resin [Dyanal BR-85J (manufactured by Mitsubishi Rayon Co., Ltd.)
A solution of 209 dissolved in 1,2-dichloroethane (1,000 r, A generation layer was formed, and the coatability of the carrier generation layer was evaluated.

To determine whether the coating properties of the carrier generation layer are good or bad, the relative falling rate (C/S) of the coating liquid level during dip coating of the carrier generation layer is 0.6 (cm/sec), 1
．． 2 (cm/5ec) when the carrier generation layer is coated, the adhesion r of the carrier generation layer per 100 Cu' (1dm2) is measured, and this value is the relative falling rate of 1.2
(cm/5ec), if it was less than 2mg/di', it was judged as a coating failure. Also, regarding the agglomeration of the carrier generation layer, visually check for uneven concentration in the carrier generation layer! 9
If agglomeration was observed, the coating was judged to be defective.

The results are shown in Table 1.

Below margin (α1) Organic pigment rKET RED 305J (Dainippon Ink Chemical Co., Ltd.) (α2) R pigment rKET RED 309J (Dainippon Ink Chemical Co., Ltd.) (α3) Organic pigment rKET RED 311J (Dainippon Ink Chemical Co., Ltd.) (manufactured by Kogyosha) (α4) Organic pigment r KET Yellow 4
03 J (manufactured by Dainippon Ink and Chemicals) (α5) Organic pigment fKET Yellow406J (
(manufactured by Dainippon Ink and Chemicals) (α6) Organic pigment rKET Green201J (manufactured by Dainippon Ink and Chemicals) (α7) Pigment with the following structure (β) Conductive titanium oxide "500w" (manufactured by Ishihara Sangyo Rei) ( γ) Carbon black "Mogulshi" (manufactured by -1-Yabot 1~) Binder (X) Phenolic resin "5K-1031 (manufactured by Sumitomo Schless) Binder (Y) Phenolic resin rsK-3J (manufactured by Sumitomo Schless) Binder (Z) Phenolic resin rsK-107J (manufactured by Sumitomo Schless) Binder (S) Silicone resin rKR-251J (Shin-Etsu Chemical Co., Ltd.) Binder (T) Polyvinyl butyral “S-LEC BM-2J (manufactured by W4 Suikagaku Kogyo Co., Ltd.) Solvent (1) Tetrahydrofuran (THF) Q
UIJO Σ ΣQ
OQ
0 As shown in Table 1, when a carrier generation layer containing a specific azo compound as a carrier generation substance is formed on a charge blocking layer (or subbing layer) containing a novolac type phenolic resin, the coating properties are improved. It was good. On the other hand, coating properties other than combinations of novolac type phenolic resin and specific azo compounds were poor.

<Preparation of photoreceptor> Photoreceptors were prepared only for the combinations in Table 1 that ensured a suspension with CGL of 211 (1/d12 or more). is the same as, but the m of CGL is 2±0.1m.
The C/S (relative drop rate of the liquid level during dip application) was adjusted so that the ratio was 0.9 g/df.

In addition, combinations other than those in Table 1 in which no substances were added to the undercoat layer were similarly prepared.

Further, on the carrier generation layer, 100 g of a carrier transporting substance represented by the following structural formula (5) and a polycarbonate resin [UbiO/Z-200J (manufactured by Mitsubishi Gas Corporation) 200 (l and 1.2- dichloroethane 1000d
The Ct5 solution for carrier transport layer obtained by dissolving the carrier transport layer was applied by dip coating and dried at a temperature of 90'C for 1 hour to form a carrier transport layer with a film thickness of 25 μm. A photoreceptor was made.

Structural formula (5) The formulation of each photoreceptor is shown in Table 2.

Below is the margin <Image evaluation (1)> (Example 2. Comparative example 2) Photoreceptor A-
1 and a-r (but without g, h, i),
Laser printer rLIPs-10PLUS that uses a semiconductor laser (wavelength 780r+m, output 2mW) as a light source
J (manufactured by Konica) installed on a modified machine, V)l is 165
After adjusting the grid voltage to 0±10 [V], develop bias DC-500 [V] +AC1oo
O[V] (2 KHz was applied and reversal development was performed in a non-contact manner, and the resulting image was evaluated for black spots in the white background, moire in the halftone dot area, and image in the black background (!JIR degree).

For evaluation of black spots, the particle size and number of black spots were measured using an image analysis device "Omnicon 3000" (manufactured by Shimadzu Corporation), and the black spots with a diameter of 0.05111111 or more were determined to be 1 per CIl12. Judgment was made based on how many there were. The criteria for black body evaluation are as shown in Table 3.

Margin Table 3 Below, moire evaluation is performed by evaluating the presence or absence of moire in the 'WI point image part with a black ground area ratio of 30% using eye n1.
indicates that there is no moire, and × indicates that there is no moire.

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

Margin Table 4 Below, as shown in Table 4, when the photoreceptor of the present invention was used, satisfactory results were obtained for black spots, seven areas, and image@density.

On the other hand, when comparative photoreceptors a to f (in which the content in the undercoat layer was conductive titanium oxide or carbon black) were used, no potential was applied and image evaluation could not be performed in any of them.

Further, when comparative photoreceptors j to O (with CGM aggregation) were used, black spots occurred in all of them. When comparative photoreceptors p to r (without inclusions in the undercoat layer) were used, good results were obtained for black spots due to the blocking effect of the undercoat layer, but the sensitivity was low. Therefore, the image 1 degree was extremely low and moire also occurred.

Image evaluation (2) > (Example 3) Photoreceptors A to I of the present invention were used in the rLIPs-10PLUS
When installed on a J-modified machine, we conducted a long run test of 10,000 cycles under a low temperature, low humidity environment of 10℃ 20% and a high temperature and high humidity environment of 30℃ 80%, and no black spots were observed in either environment. High-density images without moiré, fog, etc. were stably obtained.

The conditions for forming both images are as follows.

Grid voltage knee 600[V] Total charging current: 0.6+11A Developing bias: DC-500[V] +AC1000[V] (2KH2
) Development: Non-contact - component magnetic brush development

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the photoreceptor of the present invention, FIG. 2 is a schematic diagram of the configuration of an image forming apparatus, FIG. 3 is a schematic diagram of the configuration of a laser beam scanner for image exposure, and FIG. 4 is a schematic diagram of a developing device. Partial sectional view,
FIG. 5 is a flowchart showing the process of image formation, FIG. 6 is a sectional view of a conventionally used photoreceptor, and FIG. 7 is a sectional view of the photoreceptor for explaining the cause of moire. 1... Conductive substrate 3... Carrier transport layer 2.
...Carrier R raw layer 5...Charge blocking layer 4.
... Photosensitive layer 18 ... Fixing device 16 ... Static eliminator 17 ... Cleaning device 12 ... Developing device 13 ... Pre-transfer exposure lamp 14 ... Transfer device 9 ... Charger 10. ...Image carrier 1
9... Ray+f -23... Polygon mirror 24... For imaging -φ lens 20.25... Cylindrical lens 29... Laser beam 30... Developing sleeve

Claims (2)

[Claims] (1) On the charge blocking layer containing an organic pigment and a novolac type phenolic resin, the following general formula [
1. A photoreceptor comprising a carrier-generating layer and a carrier-transporting layer that contain a compound having a coupler represented by A] and at least two azo groups in the molecule as a carrier-generating substance, and a carrier-transporting layer. General formula [A] ▲ Numerical formulas, chemical formulas, tables, etc. or represents an unsubstituted amino group, or a substituted or unsubstituted alkoxy group, and s is 0
-4, and r represents 0-2. ] (2) In an image forming method using a photoreceptor having a photosensitive layer comprising a carrier transport layer provided on a carrier generation layer, (a) a coupler represented by the following general formula [A] is contained in the molecule; a carrier generation layer containing a compound having at least two azo groups in its molecule as a carrier generation substance; a carrier generation layer containing a novolac type phenol resin and an organic pigment, and between the carrier generation layer and the conductive substrate; (b) the absolute value of the charging potential on the photoreceptor is 400;
After applying a charge of V to 900 V, an electrostatic latent image is formed by exposure, and then a voltage of 0 to 900 V is applied, which is 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 an absolute value as low as 200V. General formula [A] ▲ Numerical formulas, chemical formulas, tables, etc. or represents an unsubstituted amino group, or a substituted or unsubstituted alkoxy group, and s is 0
-4, and r represents 0-2. ]