JPH0518425B2 - - Google Patents

Description

[Detailed description of the invention]

B. Field of Industrial Application The present invention relates to a photoreceptor, for example, an electrophotographic photoreceptor. B. Prior Art Conventionally, electrophotographic photoreceptors sensitive to visible light have been widely used in copying machines, printers, and the like. Such electrophotographic photoreceptors include selenium,
Inorganic photoreceptors provided with a photosensitive layer mainly composed of an inorganic photoconductive substance such as zinc oxide or cadmium sulfide are widely used. However, such inorganic photoreceptors do not necessarily satisfy the characteristics such as photosensitivity, thermal stability, moisture resistance, and durability required of electrophotographic photoreceptors for copying machines and the like. For example, since selenium crystallizes due to heat or fingerprint stains when touched, the above-mentioned characteristics as an electrophotographic photoreceptor tend to deteriorate. Further, electrophotographic photoreceptors using cadmium sulfide have poor humidity resistance and durability, and electrophotographic photoreceptors using zinc oxide have problems in durability. Further, electrophotographic photoreceptors made of selenium and cadmium sulfide both have toxicity, and have the drawback of being subject to significant restrictions in manufacturing and handling. In order to overcome these problems with inorganic photoconductive materials, attempts have been made to use various organic photoconductive materials in the photosensitive layer of electrophotographic photoreceptors, and active research and development has been carried out in recent years. ing. For example, Japanese Patent Publication No. 50-10496 discloses an organic photoreceptor having a photosensitive layer containing a CT complex (charge transfer complex) of poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. Are listed. However, this photoreceptor also has insufficient 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 obtain an electrophotographic photoreceptor with arbitrary characteristics. . Therefore, it is expected that organic photoreceptors with high sensitivity and durability can be obtained. Carrier generating substances that are effective for the carrier generating layer of such a functionally separated electrophotographic photoreceptor include:
Many substances have been proposed so far. An example of using an inorganic substance is amorphous selenium, as described in Japanese Patent Publication No. 16198/1983. This carrier generating layer containing amorphous selenium is used in combination with a carrier transport layer containing an organic carrier transport material. However, as described above, this carrier generation layer made of amorphous selenium has the problem that it is crystallized by heat or the like and its properties deteriorate. Furthermore, examples of using an organic substance as the carrier generating substance include organic dyes and organic pigments. For example, those having a photosensitive layer containing a bisazo compound are disclosed in JP-A-47-37543, JP-A-55-22834, JP-A-54-79632, and JP-A-56-116040. It is already known from etc. However, although these known bisazo compounds exhibit relatively good sensitivity in the short or medium wavelength range, their sensitivity in the long wavelength range is low;
It has been difficult to use it in laser printers that use semiconductor laser light sources that are expected to have high reliability. Gallium-aluminum-arsenic (Ga-Al-As) is currently widely used in semiconductor lasers.
The 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, it has been considered to add a sensitizer to photosensitive materials such as selenium and cadmium sulfide, which have high sensitivity in the visible light region, to extend the wavelength to a longer wavelength. It does not have sufficient environmental resistance against temperature, humidity, etc., and is also toxic, which poses problems for practical use. Furthermore, as described above, the sensitivity of many known organic photoconductive materials is usually limited to the visible light region of 700 nm or less, and as a result, there are few materials that have sufficient sensitivity in the long wavelength region. Among these, phthalocyanine compounds, which are one of the organic photoconductive materials, are known to have a photosensitive range extended to longer wavelength regions than other compounds. Various crystalline forms of phthalocyanine have been discovered in the process of converting α-type phthalocyanine into stable crystalline β-type phthalocyanine. Examples of these phthalocyanine compounds exhibiting photoconductivity include the X-type metal-free phthalocyanine described in Japanese Patent Publication No. 49-4338. Although this X-type metal-free phthalocyanine has sensitivity in a long wavelength region and has superior properties compared to other crystalline metal-free phthalocyanines, it is still insufficient. Further, as a phthalocyanine compound, for example, τ-type metal-free phthalocyanine described in JP-A-58-182639 is also known. As shown in Fig. 14, this τ-type metal-free phthalocyanine has a black angle 2θ of 7.6 degrees with respect to the Cu Kα characteristic X-ray (wavelength 1.541 Å) (hereinafter, this X-ray is referred to as Cu Kα (1.541 Å)). , 9.2 degrees, 16.8 degrees, 17.4 degrees, 20.4
It has a peak at 20.9 degrees and 20.9 degrees. Also, in the infrared absorption spectrum, between 700 and 760 cm ^-1
4 absorption bands with the strongest 752±2cm ^-1 , 1320~
Two absorption bands of almost equal strength between 1340 cm ^-1 ,
There is a characteristic absorption band at 3288±2cm ^-1 . but,
This τ-type metal-free phthalocyanine is produced by combining α-type metal-free phthalocyanine with a grinding aid such as salt and an inert organic solvent such as ethylene glycol at 50 to 180°C.
Preferably, it is manufactured by wet kneading at 60 to 130°C for 5 to 20 hours, so the manufacturing method is complex and difficult. Therefore, it is not always possible to obtain a τ-type phthalocyanine having a certain crystal form, and when this is used as a carrier generating material, the properties of an electrophotographic photoreceptor are insufficiently stable. Therefore, this τ-type metal-free phthalocyanine is easier to manufacture than the X-type metal-free phthalocyanine.
It has poor crystal stability and potential stability for repeated use when used as a carrier generating material for electrophotographic photoreceptors. By the way, known photoreceptors using organic photoconductive substances are generally used for negative charging. The reason for this is that when using negative charging, holes have a high mobility among the carriers, so it is possible to use hole-transporting materials, which is advantageous in terms of photosensitivity, etc.; This is because there are few materials with excellent properties, or they are carcinogenic, so they cannot be used. However, it has been found that using such negative charging causes the following problems. (1) During negative corona discharge or negative charging by a charger, a large amount of ozone is generated in the atmosphere, worsening environmental conditions. As a result, the material on the surface of the photoreceptor deteriorates, and ionic substances generated by charging adhere to the surface of the photoreceptor, resulting in a drop in potential during repeated use, causing image defects and image blurring, and extending the lifespan of the photoreceptor. It also affects. In addition, uneven discharge tends to occur due to dirt on the discharge wire of the corona discharger, so that uneven images may occur. (2) A toner of positive polarity is required for development of a negatively charged photoreceptor, but toner of positive polarity is difficult to manufacture in view of the triboelectrification series with respect to ferromagnetic carrier particles. Therefore, it has been proposed to use a positively charged photoreceptor using an organic photoconductive substance. for example,
A photoreceptor in which a carrier transport layer is laminated on a carrier generation layer and the carrier transport layer is formed of a material having a high electron transport ability can be used for positive charging. However, as described above, there are almost no electron-transporting materials that have excellent properties, or they cannot be used due to environmental considerations, so the positive charging photoreceptor described above is not practical. For example, in order to provide the carrier transport layer with electron transport ability, trinitrofluorenone has been included, but this substance is inappropriate because it is carcinogenic. On the other hand, a positive charging photoreceptor can be considered in which a carrier generation layer is laminated on a carrier transport layer with a high hole transport ability, but this has a very thin carrier generation layer on the surface side, so the printing durability and durability are poor. , the sensitivity stability during repeated use deteriorates, and this is not a practical layer structure. In addition, as a photoreceptor for positive charging, the U.S. Patent No.
No. 3,615,414 discloses a material containing a thiapyrylium salt (carrier generating substance) so as to form a eutectic complex with polycarbonate (binder resin). However, this known photoreceptor has the drawbacks of a large memory phenomenon and a tendency to generate ghosts. U.S. Patent No. 3,357,989 also discloses a photoreceptor containing phthalocyanine, but the characteristics of phthalocyanine change depending on the crystal type, and the crystal type needs to be strictly controlled. Furthermore, it lacks short wavelength sensitivity and has a large memory phenomenon, making it unsuitable for copying machines that use light sources in the visible wavelength range. Due to the above-mentioned circumstances, conventionally, it has been difficult to use a photoreceptor using an organic photoconductive substance for positive charging, and for this reason, it has been used exclusively for negative charging. C. Purpose of the Invention The purpose of the present invention is to provide a device that has sufficient sensitivity to relatively long-wavelength light such as semiconductor laser light, can operate with positive charging, and in particular generates less ozone and maintains favorable environmental conditions. It is an object of the present invention to provide a photoreceptor that can maintain a high temperature and has excellent printing durability, potential stability, memory characteristics, and residual potential characteristics. D. Structure of the invention and its effects The present invention provides a photoreceptor in which a carrier transport layer containing a carrier transport substance and a binder substance, and a carrier generation layer containing a carrier generation substance and a binder substance are laminated in this order. Black angle 2θ for X-ray of Cu Kα1.541Å
(However, the error is 2θ ± 0.2 degrees) is 7.7 degrees, 9.3 degrees, 16.9 degrees
It has an X-ray crystal diffraction spectrum with main peaks at 17.5 degrees, 22.4 degrees, and 28.8 degrees, and the intensity ratio of the peak at a black angle of 16.9 degrees to the peak at a black angle of 9.3 degrees in this X-ray diffraction spectrum is
0.8 to 1.0, and the intensity of each peak at the black angle of 22.4 degrees and 28.8 degrees with respect to the peak at the black angle of 9.3 degrees is 0.4 or more, and
It has an infrared absorption spectrum with peaks at 700 to 760 cm ^-1 , 1320 ± 2 cm ^-1 and 3288 ± 3 cm ^-1 ,
There are four peaks in the absorption band from 700 to 760 cm ^-1 .
A photoreceptor characterized in that the carrier generation layer contains a metal-free phthalocyanine, of which 752±2 cm ^-1 is the strongest, and further contains a compound represented by the following general formula [] in the carrier generation layer. Related. General formula []: (However, R ¹ represents a substituted or unsubstituted aryl group, R ² represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an amino group,
It represents a substituted amino group or a hydroxyl group, and R ₃ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. ) The photoreceptor of the present invention has a laminated structure in which a carrier generation layer is laminated on a carrier transport layer. The above-mentioned "layer" also contains a carrier-generating substance and a carrier-transporting substance (a compound represented by the general formula This corresponds to the generation layer. Since the photosensitive layer of the photoreceptor of the present invention has the above-described structure, it is particularly suitable for use with positive charging. Moreover, since the above-mentioned photoreceptor uses metal-free phthalocyanine having the main peak of the above-mentioned Black angle as a carrier generating substance in the above-mentioned "layer", the potential stability during repeated use of the photoreceptor is improved. , there is little memory phenomenon, the residual potential is low and stable, and the crystals of the phthalocyanine itself are stable, making it easy to manufacture. In addition, since this metal-free phthalocyanine exhibits high sensitivity in a long wavelength region, the photoreceptor of the present invention is suitable for semiconductor lasers and the like. Further, according to the photoreceptor of the present invention, a "layer" is used in which a carrier generating substance and a carrier transporting substance are bound together with a binder substance.
There are various advantages by providing a thicker layer. That is, since the above-mentioned "layer", that is, the carrier generation layer is provided on the upper layer, it has a configuration for positive charging, but in this case, by providing the carrier generation layer thicker, the printing life, which is the problem mentioned above, is reduced. You can fully satisfy your sexual needs. For example, it is much thicker than what is normally considered (approximately 0.2 μm when using a negative charge).
When the carrier generation layer is provided with a thickness of 0.6 to 10 μm (preferably 1 to 8 μm), good printing durability, durability, and sensitivity stability during repeated use can be obtained. In addition, in the photoreceptor of the present invention, if the content of the binder substance in the "layer" is increased, the film strength on the surface of the photoreceptor is improved, it is possible to prevent the surface of the photoreceptor from being scraped during processes such as cleaning, and the wear resistance is improved. , it becomes possible to improve printing durability and sensitivity stability during repeated use. However, in a photoreceptor using the above-mentioned "layer", if the "layer" is provided thickly, and if only the carrier-generating substance is included, as the "layer" becomes thicker, the "layer" becomes thicker. The concentration of the carrier-generating substance therein is relatively reduced, and the transport distance of the positive and negative carriers from the carrier-generating position becomes large, resulting in a significant reduction in the transport ability of the carriers. Also, as the amount of binder material in the "layer" is increased, the concentration of the carrier generating material decreases and the carrier transport ability decreases. This results in a decrease in sensitivity of the photosensitive layer, an increase in residual potential, an increase in memory phenomenon, a decrease in sensitivity during repeated use, and a decrease in charging potential. On the other hand, in the photoreceptor of the present invention, the "layer"
Because a specific carrier transport substance is added inside,
A technical solution to the above-mentioned problem becomes possible. Here, the specific carrier transport substance is a compound (carbazole derivative) represented by the general formula [] above.
It is. The reason why we selected this specific carrier transport material is that there is selectivity in carrier injection from the metal-free phthalocyanine, which is a carrier generating material, to the carrier transport material in the same layer inside the "layer". This is because it will be done. That is, if the carrier transport material of the present invention is selected, the above-mentioned carrier injection can be performed efficiently because the ionization potential is compatible with the metal-free phthalocyanine of the present invention, and the thickness of the "layer" can be reduced. Even if the size and the concentration of the binder substance are increased, the transport capacity of the carrier generated within the "layer" does not decrease, but rather increases, and therefore always has a good
Sensitivity characteristics, residual potential characteristics, memory characteristics, sensitivity characteristics during repeated use, and charging potential characteristics can be enjoyed. Further, the carrier transport material of the present invention has excellent hole transport ability, and by including it in the "layer", a photoreceptor suitable for use with positive charging can be obtained. In the above-mentioned "layer" constituting the photoreceptor of the present invention, a particulate carrier-generating substance and a carrier-transporting substance are bound together by a binder substance (that is, dispersed in the layer in the form of a pigment). Good. In this case, the printing durability and durability of the "layer" will be good,
There is little memory phenomenon and the residual potential is stable. From the structure of the "layer" described above, the compatibility between the carrier transport material and the binder material influences the properties of the photosensitive layer. In this respect, the carrier transport material of the present invention has excellent compatibility as described above. Further, when using positive charging, unlike when using negative charging, the amount of ozone generated can be suppressed to a low level, but a small amount of ozone generation is still unavoidable. However, the charge transport material of the present invention is less susceptible to deterioration due to ozone adsorption, and therefore less likely to cause image blur or image defects. Additionally, the charge transport materials of the present invention are safe, environmentally friendly, and chemically stable. As described above, the present invention makes it possible to provide a photoreceptor suitable for use with positive charging. This makes it possible to exhibit the unique characteristics of using positive charging and solving the problems associated with using negative charging described in the section of the prior art. That is, the amount of ozone generated can be kept low and the environmental conditions can be made favorable, and various problems such as uneven discharge due to dirt on the discharge electrode can be avoided, and a negative polarity toner that is easy to manufacture can be used. . Furthermore, since it is a functionally separated type, it has high sensitivity and high durability, and the selection of constituent materials is easy. The metal-free phthalocyanine used in the present invention has a characteristic X-ray diffraction spectrum that is not found in conventional metal-free phthalocyanines (for example, the τ-type metal-free phthalocyanine shown in FIG. 12). That is, it has a characteristic peak at a black angle of 28.8 degrees. For example, as an example of the X-ray diffraction spectrum exhibited by the metal-free phthalocyanine used in the present invention,
Examples include those shown in the figure. Furthermore, the metal-free phthalocyanine used in the present invention has an infrared absorption spectrum with a peak at 700 to 760 cm ^-1 , as shown in Figure 4.
There are four peaks in the cm ^-1 absorption band, of which
It is characterized by being the strongest at 720±2cm ^-1 . In addition, the visibility of metal-free phthalocyanine in Figure 3,
As shown by the solid line in Figure 5, the near-infrared absorption spectrum desirably has an absorption maximum at 770 nm or more and below 790 nm, and the τ-type metal-free phthalocyanine shown by the broken line has an absorption maximum at 790 to 820 nm, and most It is different from the one that has an absorption maximum at 810nm. In order to produce the metal-free phthalocyanine according to the present invention, the α-type metal-free phthalocyanine shown in FIG. The metal-free phthalocyanine shown in FIG. 3 is obtained by obtaining a metal-free phthalocyanine and then subjecting the metal-free phthalocyanine to a solvent treatment such as a dispersion treatment with a non-polar solvent such as tetrahydrofuran. For milling with stirring or kneading, a dispersion medium that is normally used for dispersing, emulsifying, or mixing pigments, such as glass beads, etc.
Steel beads, alumina balls, flint stones, etc. are used. However, distributed media is not necessarily required. A grinding aid may also be used, and as this grinding aid, those commonly used for pigments may be used, such as common salt, bicarbonate of soda, sulfur salt, and the like. However, this grinding aid is also not necessarily required. The metal-free phthalocyanine shown in Figure 1 is Cu
Black angle of Kα (1.541 Å) with respect to X-rays (however, error is 2θ ± 0.2 degrees) 7.5 degrees, 9.1 degrees, 16.7 degrees,
It has peaks at 17.3 degrees and 22.3 degrees, and its infrared diffraction spectrum is 746 cm ^-1 , as shown in Figure 2.
Three peaks between 700 and 750 cm ^-1 , 1318 cm ^-1 ,
There is an equal peak of intensity at 1330 cm ^-1 . If a solvent is required during stirring, kneading, or grinding, it is preferable to use a solvent that is liquid at the temperature at which these operations are performed. Alternatively, it is preferable to select one or more solvents selected from the group of polyethylene glycol solvents, cellosolve solvents such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ketone solvents, and ester ketone solvents. Typical devices used in the crystal transition process include a general stirring device,
For example, there are homomixers, dispersers, agitators, stirrers, kneaders, Banbury mixers, ball mills, sand mills, attritors, and the like. The superior properties of the metal-free phthalocyanine of the present invention produced as described above are such that the production method does not necessarily require a grinding aid and therefore does not require its removal, and temperature control is possible. The method for producing τ-type phthalocyanine does not have to be strict and can be easily carried out, for example, at room temperature. is different. In addition, the metal-free phthalocyanine of the present invention has an extremely stable crystalline form, and can be immersed in organic solvents such as acetone, tetrahydrofuran, toluene, ethyl acetate, and 1,2-dichloroethane, for example,
Even when subjected to heat resistance tests such as being left in an atmosphere of ℃ for 50 hours or more, or applying mechanical strain such as milling, it is less likely to transition to other crystal forms, which is better than the conventional τ type. Of course, it is excellent (phthalocyanine shown in FIG. 3 is particularly good in this respect). This makes it possible to produce the metal-free phthalocyanine of the present invention with less variation in quality,
In addition to the above, it is possible to further facilitate the manufacture of the electrophotographic photoreceptor, and improve characteristics such as potential stability during repeated use when used in an electrophotographic photoreceptor. The above-mentioned metal-free phthalocyanine used in the present invention has the following structural formula, and can be mainly divided into those shown in FIG. 1 and those shown in FIG. 3 depending on its thermodynamic state. Next, examples of the carbazole derivatives of the general formula [] used as carrier transport materials in the present invention include those having the following structural formulas, but are not limited thereto.

【table】

【table】

【table】

[Table] In the present invention, one or more other carrier generating substances may be used in combination with the metal-free phthalocyanine described above. Examples of carrier-generating substances that can be used in combination include α-type, β-type, and γ-type.
Examples include metal-free phthalocyanines of type, τ type, τ′ type, η type, and η′ type. Other examples include phthalocyanine pigments, azo pigments, anthraquinone pigments, perylene pigments, polycyclic quinone pigments, methine squaritate pigments, and the like. Examples of azo pigments include the following. (-5) A-N=N-Ar ¹ -CH=CH-Ar ² -N=N-
A (-6) A-N=N-Ar ¹ -CH=CH-Ar ² -CH=CH
−Ar ³ −N=N−A (-8) A-N=N-Ar ¹ -N=N-Ar ² -N=N-A (-9) A-N=N-Ar ¹ -N=N-Ar ² -N=N-Ar ³
-N=N-A [However, in each of the above general formulas, Ar ¹ , Ar ² and Ar ³ are each substituted or unsubstituted carbocyclic aromatic ring group, R ⁴ , R ⁵ , R ⁶ and R ⁷ are each electron-withdrawing group or hydrogen atom, at least one of R ⁴ to ^{R 7} is an electron-withdrawing group such as a cyan group,

【formula】

【formula】

【formula】

【formula】 or

【formula】 (X is a hydroxy group,

[Formula] or -NHSO ₂ -R ¹¹ <However, R ⁹ and R ¹⁰ are each a hydrogen atom or a substituted or unsubstituted alkyl group, R11 is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group> , Y is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an alkoxyl group, a sulfo group, a substituted or unsubstituted carbamoyl group, or a substituted or unsubstituted sulfamoyl group (provided that m is 2 or more) ), Z is an atomic group necessary to constitute a substituted or unsubstituted carbocyclic aromatic ring or a substituted or unsubstituted heterocyclic aromatic ring, R ⁸ is a hydrogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a carboxyl group or an ester group thereof, Ar ⁴ is a substituted or unsubstituted aryl group, n is an integer of 1 or 2, m is an integer from 0 to 4. )] Polycyclic quinone pigments of the following general formula [] group can also be used as carrier generating substances. General formula []: (However, in this general formula, X' is a halogen atom,
It represents a nitro group, a cyano group, an acyl group, or a carboxyl group, n represents an integer of 0 to 4, and m represents an integer of 0 to 6. ) In the present invention, in the "layer", a pyrazoline compound of the following general formula [] can also be used in addition to the above-mentioned carbazole derivative. General formula []: [However, in this general formula, l: 0 or 1, R ¹² , R ¹³ and R ¹⁴ : substituted or unsubstituted R group, R ₁₅ and R ¹⁶ : hydrogen atom, alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group or aralkyl group (however, R ¹⁵ and
Both R ¹⁶ are never hydrogen atoms, and when l is 0, R ¹⁵ is not a hydrogen atom. )] Furthermore, hydrazone compounds of the following general formulas [] and [] can also be used in combination as carrier transport substances. General formula []: (However, in this general formula, R ¹⁷ : methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R ¹⁸ : methyl group, ethyl group, benzyl group, or phenyl group, R ¹⁹ : methyl group, ethyl group) group, benzyl group, or phenyl group.) General formula []: (However, in this general formula, R ²⁰ is a substituted or unsubstituted naphthyl group; R ²¹ is a substituted or unsubstituted alkyl group, aralkyl group, or aryl group; R ²² is a hydrogen atom, an alkyl group, or an alkoxy group; R ²³ and R ²⁴ are the same or different groups consisting of a substituted or unsubstituted alkyl group, aralkyl group, or aryl group.) In the present invention, as a carrier transport substance, the carbazole derivative condensed to the side chain is used as a carrier transport substance. If a high-molecular organic semiconductor having an aromatic ring or a heterocycle is used, this high-molecular organic semiconductor has a property of generating optical carriers by absorbing ultraviolet light, thereby effectively contributing to photosensitization. Therefore, the tail of the discharge curve becomes more sharp, and the sensitivity improves, especially in the low electric field region. As a result, in a conductive or insulating one-component development process, a good copy image without fog can be obtained without applying a bias voltage during the development stage. When a bias voltage is applied in a one-component development process, the sharpness of the edge of the image decreases due to the so-called fringe phenomenon, causing blurring, but such problems are reduced by using the polymeric organic semiconductor. In addition, the polymeric organic semiconductor has a high absorbance in the ultraviolet region and absorbs most of the ultraviolet light, and has a kind of Frilter effect against ultraviolet light, so it has the effect of preventing the deterioration of the carbazole compound and is photosensitive. The ultraviolet light stability and durability of the layer can be improved. Examples of the above-mentioned polymeric organic semiconductors include the following examples, but the present invention is not limited thereto. Among the above-mentioned polymeric organic semiconductors, poly-N-vinylcarbazole or its derivatives are highly effective and are preferably used. Such poly-N-vinylcarbazole derivatives mean that all or part of the carbazole ring in the repeating unit has various substituents, such as an alkyl group, a nitro group, an amino group,
It is substituted with a hydroxy group or a halogen atom. Further, in a photoreceptor having a laminated structure, the carrier transport material used in the carrier transport layer may be the above-mentioned carbazole derivative, but unlike the carrier generation layer, it does not necessarily have to be a main component thereof. Namely, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxazolone derivatives, benzo Thiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, poly-N-vinylcarbazole,
It may be one or more selected from poly-1-vinylpyrene, poly-9-vinylanthracene, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, and the like. The structure of a photoreceptor, such as an electrophotographic photoreceptor, based on the present invention can take various forms. General configurations are illustrated in FIGS. 6 to 9. The photoreceptor shown in FIG. 6 has a laminated structure, in which a carrier transport layer 3 in which a carrier transport material is dispersed in a binder material is provided on a conductive support 1, and on this layer 3, the above-mentioned metal-free phthalocyanine,
The photosensitive layer 4 is constructed by forming a carrier generation layer containing the above-mentioned carbazole derivative as a main component in a binder substance. The photoreceptor shown in FIG. 8 has a single layer structure, and has a layer 6 on a conductive support 1 containing the above-mentioned metal-free phthalocyanine and the above-mentioned carbazole compound as main components in a binder substance. Forming a single layer type photosensitive layer 4
That is. The photoreceptors shown in FIGS. 7 and 9 are shown in FIGS. 6 and 9, respectively.
In the layer structure shown in FIG. 8, an intermediate layer 5 is provided between the photosensitive layer 4 and the conductive support 1 to effectively prevent injection of free electrons into the conductive support 1. The intermediate layer 5 may be made of a high molecular weight polymer, polyvinyl alcohol, ethyl cellulose, etc. as explained above as the binder resin.
An organic polymer material such as carboxymethyl cellulose or a material made of aluminum oxide or the like is used. In FIGS. 6 to 9, a protective layer (film) may be further formed on the surface to improve printing durability, for example, a synthetic resin film may be coated. The carrier generation layer 2 or layer 6 when forming the photosensitive layer having the above structure can be provided by the following method. (a) A method of applying a solution in which a carrier-generating substance is dissolved in a suitable solvent, or a solution in which a binder is added and mixed and dissolved. (b) A method in which a carrier-generating substance is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder is added as necessary to mix and disperse the obtained dispersion, and the resulting dispersion is applied. Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion. Solvents or dispersion media used to form the carrier generation layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, and toluene. , xylene, chloroform,
Examples include 1,2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, and dimethyl sulfoxide. When a binder is used to form the photosensitive layer, any binder can be used, but a high molecular weight polymer that is hydrophobic, has a high conductivity, and has the ability to form an electrically insulating film is particularly preferred. Examples of such polymers include, but are not limited to, the following: a Polycarbonate b Polyester c Methacrylic resin d Acrylic resin e Polyvinyl chloride f Polyvinylidene chloride g Polystyrene h Polyvinyl acetate i Styrene-butadiene copolymer j Vinylidene chloride-acrylonitrile copolymer k Vinyl chloride-vinyl acetate copolymer l Vinyl chloride -Vinyl acetate-Maleic anhydride copolymer m Silicone resin n Silicone-alkyd resin o Phenol-
Formaldehyde resin p Styrene-alkyd resin q Poly-N-vinylcarbazole r Polyvinyl butyral These binders can be used alone or in a mixture of two or more. “Layer” (sixth layer) constituting the photoreceptor based on the present invention
, carrier generation layer 2 in FIG. 7 and FIGS. 8 and 9.
(including any of the photosensitive layers 6 having a single-layer structure shown in the figure), the carrier generating substance is added to the binder substance, and the carrier generating substance/binder substance = 5 to 5.
150% (i.e. 5 parts by weight for 100 parts by weight of binder material)
If the content is within a specific range of 150 parts by weight, preferably 10 to 100 parts by weight, a positive charging photoreceptor with less reduction in residual potential and acceptance potential can be provided. Outside the above range, if the carrier generating substance is small, the photosensitivity will be poor and the residual potential will increase, and if it is too large, the acceptance potential will drop a lot and the memory will tend to increase. Also,
The content of carrier transport substance in the above “layer” is also important, carrier transport substance/binder substance = 20
~200% (i.e. for 100 parts by weight of binder material)
(20 to 200 parts by weight, preferably 50 to 120 parts by weight); within this range, the residual potential is low and the photosensitivity is good, and the solvent solubility of the carrier transport substance is also maintained well. Outside this range, if the carrier transport substance is small, the residual potential and photosensitivity tend to deteriorate, resulting in poor images, white spots, blurring, etc., and if it is too large, solvent solubility tends to deteriorate.
The film strength tends to be low. The content range of this carrier transport substance may be the same in the carrier transport layer 3 shown in FIGS. 6 and 7. In addition, the ratio of the carrier-generating substance and the carrier-transporting substance in the “layer” is such that the weight ratio of the carrier-generating substance to the carrier-transporting substance is (1:
0.2) to (1:10), and (1:
0.5) to (1:7) is even better. If the proportion of the carrier-generating substance is smaller than this range, the photosensitivity will be insufficient, and if the proportion is large, the carrier transport ability will decrease, resulting in insufficient sensitivity. When the above-mentioned "layer" is a carrier generation layer, the thickness of the carrier generation layer 2 is preferably 0.6 to 10 μm, more preferably 1 to 8 μm. If this thickness is less than 0.6 μm, the surface of the carrier generation layer will be mechanically damaged during repeated use due to usage conditions such as development and cleaning, resulting in part of the layer being scraped off or black streaks appearing on the image. Sometimes it appears. Further, if the diameter is less than 0.6 μm, the sensitivity tends to be insufficient. However, if the thickness of the carrier generation layer exceeds 10 μm, the number of thermally excited carriers will increase, and as the environmental temperature increases, the acceptance potential will decrease, memory phenomenon will increase, and image density will likely decrease. . Furthermore, when irradiating light with a wavelength longer than the absorption edge of the carrier-generating substance, optical carriers are generated even near the bottom of the charge-generating layer. In this case, electrons must move through the layer to the surface, and generally sufficient transport ability tends to be difficult to obtain. Therefore, during repeated use, the residual potential tends to increase. Further, when the above-mentioned "layer" is a photosensitive layer having a single layer structure, the thickness of the photosensitive layer is preferably 10 to 50 μm, and more preferably 15 to 30 μm. If the film thickness is less than 15 μm, the charging potential will be low because it is thin, and the printing durability will be poor. Furthermore, if the thickness of the photosensitive layer 6 exceeds 50 μm, the residual potential will increase, 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. Further, the thickness of the carrier transport layer 3 shown in FIGS. 6 and 7 is preferably 5 to 50 μm, preferably 5 to 30 μm. If the thickness is less than 5 μm, the charged potential will be small because it is thin, and if it exceeds 50 μm, the residual potential will tend to become large. Further, it is desirable that the film thickness ratio between the carrier generation layer and the carrier transport layer is 1:(1 to 30). When the photosensitive layer is formed by dispersing the carrier-generating substance, the carrier-generating substance has a diameter of 5 μm or less, 0.1 μm or more, preferably 2 μm or less,
It is preferable that the powder has an average particle size of 0.2 μm or more. In other words, if the particle size is too large, dispersion in the layer will be poor, and some of the particles will protrude from the surface, resulting in poor surface smoothness, and in some cases, discharge may occur at the protruding portions of the particles. Toner particles tend to adhere there, causing a toner filming phenomenon. Long wavelength light (~
7000 nm), the surface charge is neutralized by the generation of thermally excited carriers in the carrier-generating substance, and it is thought that this neutralization effect is greater when the particle size of the carrier-generating substance is large. Therefore, high resistance and high sensitivity can only be achieved by reducing the particle size. However, if the particle size is too small, it tends to aggregate, which increases the resistance of the layer, increases crystal defects, reduces sensitivity and repeatability, and reduces charging ability. Further, since there is a limit to miniaturization, it is desirable that the lower limit of the average particle size is 0.01 μm. Furthermore, the photosensitive layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, and the like. Examples of electron-accepting substances that can be used here include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromo phthalic anhydride, 3-nitro phthalic anhydride, 4- Nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, paranitrobenzonitrile, picryl chloride , quinone chlorimide, chloranil, brumanil, dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, 9-fluorenylidene [dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidene-[dicyanomethylenemalonodinitrile], picric acid, o-nitro Benzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-
Examples include nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds with high electron affinity. The addition ratio of the electron-accepting substance is carrier-generating substance:electron-accepting substance=100:0.01-200, preferably 100:0.1-100. The support 1 on which the photosensitive layer is to be provided is a metal plate, a metal drum, or a conductive thin layer made of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold, by coating or vapor deposition. , by means such as lamination,
Those provided on a substrate such as paper or plastic film are used. As the intermediate layer which functions as an adhesive layer or a buyer layer, a material made of a polymer such as the binder resin described above, an organic polymer material such as polyvinyl alcohol, ethyl cellulose, or carboxymethyl cellulose, or aluminum oxide is used. It will be done. A major feature of the photoconductor of the present invention is that when the maximum value of the photosensitive wavelength range of the metal-free phthalocyanine used in the present invention exists in a range of 770 nm or more and less than 790 nm, it is optimal as a photoconductor for semiconductor lasers; As mentioned above, the crystal form is extremely stable, and transition to other crystal forms is unlikely to occur. This is a great advantage not only in the production and properties of the metal-free phthalocyanine used in the present invention, but also in the production and use of electrophotographic photoreceptors. Another major feature of the present invention is that the layer containing the metal-free phthalocyanine contains a carbazole derivative as a specific charge transport substance that is compatible with the metal-free phthalocyanine. It has now become possible to provide a photoreceptor suitable for charging use. E. Examples Hereinafter, the present invention will be described in detail with reference to specific examples and comparative examples. First, a synthesis example of a metal-free phthalocyanine compound A having the properties shown in Figs. 1 to 2, a synthesis example of a metal-free phthalocyanine compound B having the properties shown in Figs. 3 to 5, and a synthesis example of a τ-type metal-free phthalocyanine compound. shows. <Synthesis Example 1> 50 g of lithium phthalocyanine was added to 600 ml of concentrated sulfuric acid that was sufficiently stirred at 0°C. The mixture was then stirred at this temperature for 2 hours.
The resulting solution was then filtered through a coarse sintered glass funnel and poured slowly into 4 liters of ice and water with stirring. After standing for several hours, the mixture was filtered and the resulting mass was washed with water until neutral. The mass was then finally washed several times with methanol and dried in air. The dried powder was extracted with acetone in a 24 hour continuous extractor and dried in air to a blue powder. In the above, the precipitation was repeated to ensure a salt residue for lithium. In this way
30.5g of blue powder was obtained. The X-ray diffraction pattern of the obtained product was consistent with the X-ray diffraction pattern of an α-type phthalocyanine compound described in previously published materials. 30 g of the metal-free α-phthalocyanine compound thus obtained was placed in a 900 ml porcelain ball mill half-filled with 13/16 inch diameter balls, and milled at approximately 80 rpm for 164 hours. A metal-free phthalocyanine compound A was obtained. This compound exhibited the X-ray diffraction spectrum shown in FIG. <Synthesis Example 2> Metal-free phthalocyanine compound A of Synthesis Example 1 and 200 ml of an organic solvent such as tetrahydrofuran or 1,2-dichloroethane were added to a ball mill and milled again for 24 hours. The organic solvent was removed from the dispersion after milling and the dispersion was dried to obtain 28.2 g of metal-free phthalocyanine compound B. This compound exhibited the X-ray diffraction spectrum shown in FIG. <Synthesis Example 3> An α-type metal-free phthalocyanine compound (Monolite Fast Bull GS manufactured by ICI) was extracted and purified three times with heated dimethyl formaldehyde. Through this operation, the purified product was transferred to the β form. Next, a portion of this β-type metal-free phthalocyanine compound was dissolved in concentrated sulfuric acid, and this solution was poured into ice water to cause reprecipitation, thereby transforming it into the α-type. This reprecipitate was washed with aqueous ammonia, methanol, etc., and then dried at 10°C. Next, α purified as above
The type-free metal phthalocyanine compound was placed in a sand mill with a grinding aid and a dispersant, and the temperature was 100±20℃.
The mixture was kneaded for 15 to 25 hours. After confirming that the crystal form has transitioned to τ type by this operation, remove it from the container,
After thoroughly removing the grinding aid and dispersant with water, methanol, etc., the product was dried to obtain blue crystals of τ-type metal-free phthalocyanine with a clear bluish tinge. This phthalocyanine showed the X-ray diffraction spectrum shown in FIG. Examples 1 to 11, Comparative Examples 1 and 2 A vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MF-10" (manufactured by Sekisui Chemical Co., Ltd.) was placed on a conductive support made of a polyester film laminated with aluminum foil. ) thickness consisting of
An intermediate layer of 0.05 μm was formed. Next, the carrier transport material shown in FIG. 10 and a binder resin (polycarbonate: Panlite L-1250) were mixed together.
A solution in 67 ml of 2-dichloroethane was applied onto the intermediate layer to form a carrier transport layer. Next, each of the carrier-generating substances and carrier-transporting substances shown in FIG. 10 with an average particle diameter of 1 μm and a binder resin were added to 67 ml of 1,2-dichloroethane and dispersed in a ball mill for 12 hours. The resulting dispersion was used as the carrier. A carrier generation layer was formed by coating and drying on the transport layer, and each electrophotographic photoreceptor was manufactured. The electrophotographic photoreceptor obtained in this way was mounted on an electrostatic tester "EPA-8100 model" (manufactured by Kawaguchi Electric Seisakusho).
The following characteristic tests were conducted. In other words, +6kV to the charger
The photosensitive layer was charged by corona discharge for 5 seconds by applying a voltage of The exposure amount required to attenuate the light by half, that is, the half-reduction exposure amount E1/2 was determined. In addition, the values of the acceptance potential V _A during charging by the corona discharge and the residual potential V _R after exposure to 10 lux·sec were measured. In addition, a photoreceptor layer similar to that shown in the example was used.
It was formed on an Al drum, mounted on a modified laser beam printer LP-3010 (manufactured by Konishiroku Photo Industry Co., Ltd.) (using a semiconductor laser light source), and image evaluation was performed (CD is image density, R is ) ◎: Density is sufficiently high and resolution is very good (CD≧1.2, R≧6.0) ○: Both density and resolution are good (1.2>CD≧0.7, 6.0>R≧4.0) ×: Density is low, and resolution is not sufficient. Additionally, fogging and white or black spots appear. In addition, CD is Sakura Densitometer (Model PDA-
65: Measured with Konishiroku Photo Industry Co., Ltd.), R is Sakura Densitometer (Model PDA-5: Konishiroku Photo Industry Co., Ltd.)
Measured at For both CD and R, the density of white paper was set to 0.0, and the reflection density was measured and evaluated. However, the specific method for measuring R was as follows. That is, the resolution chart is measured using a microdensitometer with a slit of 500μ x 20μ. The judgment criteria for the resolution chart is the following formula: 30
Judgment is made from the resolution chart with a response of % or more. If the density of the image area of the copied image is D ^copy _nax , the density of the non-image area is D ^copy _nio , the density of the image area of the original document _is ^Dorig _nax , and the density of the non-image area is Dorig ^nio , then (D ^copy / _nax − ^copy / _nio / D ^copy / _nax − ^copy / _nio )
／（D ^orig ／ _nax −D ^orig ／ _nio ／D ^orig ／ _nax −D ^orig ／ _nio
)≧30(%) According to this result, Examples 1 to 1 based on the present invention
It can be seen that all of the 11 samples exhibit considerably better electrophotographic characteristics than Comparative Examples 1 and 2. In particular, the use of the metal-free phthalocyanine compound B of the present invention as a CGM and the addition of a carbazole derivative as a CTM to the carrier generation layer both greatly influence the characteristics of the photoreceptor, resulting in a high charging potential and its stability. It is possible to obtain remarkable results as a positively charging photoreceptor, such as improved properties and greatly improved photosensitivity. In addition, high density and high resolution were obtained in tests using semiconductor lasers.
It has become clear that the long wavelength sensitivity is improved.

[Brief explanation of drawings]

1 to 10 are for explaining the present invention, and FIGS. 1 and 3 are X-ray diffraction spectra of two examples of metal-free phthalocyanine, and FIGS. 2 and 4 are metal-free phthalocyanines. Infrared absorption spectra of two examples of phthalocyanine, Figure 5 is a near-infrared spectrum of metal-free phthalocyanine, Figures 6 and 7 are partial cross-sectional views of a layer-separated photoreceptor, and Figures 8 and 7 are respectively 9
Each figure is a partial cross-sectional view of a photoreceptor having a single layer structure, and FIGS. 10 and 12 are diagrams showing a comparison of changes in characteristics of each electrophotographic photoreceptor. FIG. 11 is an X-ray diffraction spectrum diagram of a conventional τ-type metal-free phthalocyanine. In addition, in the symbols shown in the drawings, 1... conductive support, 2... carrier generation layer, 3... carrier transport layer, 4... photosensitive layer, 5... intermediate layer, 6...
It is a layer.

Claims (1)

[Scope of Claims] 1. A photoreceptor in which a carrier transport layer containing a carrier transport substance and a binder substance and a carrier generation layer containing a carrier generation substance and a binder substance are laminated in this order, with a Cu Kα of 1.541 Å. Black angle 2θ to X-rays
(However, the error is 2θ ± 0.2 degrees) is 7.7 degrees, 9.3 degrees, 16.9 degrees
It has an X-ray crystal diffraction spectrum with main peaks at 17.5 degrees, 22.4 degrees, and 28.8 degrees, and the intensity ratio of the peak at a black angle of 16.9 degrees to the peak at a black angle of 9.3 degrees in this X-ray diffraction spectrum is
0.8 to 1.0, and the intensity of each peak at the black angle of 22.4 degrees and 28.8 degrees with respect to the peak at the black angle of 9.3 degrees is 0.4 or more, and
It has an infrared absorption spectrum with peaks at 700 to 760 cm ^-1 , 1320 ± 2 cm ^-1 and 3288 ± 3 cm ^-1 ,
There are four peaks in the absorption band from 700 to 760 cm ^-1 .
A photoreceptor characterized in that the carrier generation layer contains a metal-free phthalocyanine, of which 752±2 cm ^-1 is the strongest, and further contains a compound represented by the following general formula []. General formula []: (However, R ¹ represents a substituted or unsubstituted aryl group, R ² represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an amino group,
It represents a substituted amino group or a hydroxyl group, and R ³ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group. )