JPH0530263B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a photoreceptor for electrophotography, and in particular to a photoreceptor that is highly sensitive to light with a wavelength longer than visible light and semiconductor laser light used in printers, copiers, etc. . BACKGROUND ART Conventionally, electrophotographic photoreceptors sensitive to visible light have been widely used in copying machines, printers, and the like. As such electrophotographic photoreceptors, inorganic photoreceptors provided with a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, 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 are inferior in humidity resistance and durability, and electrophotographic photoreceptors using zinc oxide have problems in durability. Further, electrophotographic photoreceptors made of selenium or cadmium sulfide have the disadvantage that there are significant restrictions in manufacturing and handling. In order to improve 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 conducted in recent years. ing. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor also has insufficient sensitivity and durability. Therefore, a functionally separated electrophotographic photoreceptor has been developed in which the photosensitive layer is divided into two layers, a carrier generation layer and a carrier transport layer are separately configured, and each layer contains a carrier generation substance and a carrier transport substance. This is because the carrier generation function and the carrier transport function can be assigned to different substances, and the substances that perform each function can be selected from a wide range of materials. The body can be obtained relatively easily. 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, as a device having a photosensitive layer containing a bisazo compound,
JP-A-47-37543, JP-A-55-22834, JP-A-54-79632, JP-A-56-116040
This is already known from publications such as No. 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, making them difficult to use in laser printers that use semiconductor laser light sources, which are expected to be highly reliable. That was difficult. Currently, gallium-aluminum-arsenic (Ga, Al,
As) type light emitting elements have 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 high sensitivity in the visible light region.
A method of adding a new sensitizer to photosensitive materials such as Se and CdS to make the wavelength longer has been considered, but Se,
As mentioned above, CdS does not have sufficient environmental resistance against temperature, humidity, etc., and there are still problems. Furthermore, as mentioned above, the sensitivity of many known organic photoconductive materials is usually limited to the visible light region of 700 nm or less, and there are few materials that have sufficient sensitivity in longer wavelength regions. 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 τ-type metal-free phthalocyanine described in JP-A-58-182639. This τ
As shown in FIG. 4, the type metal-free phthalocyanine has peaks at black angles of 7.6, 9.2, 16.8, 17.4, 20.4, and 20.9 with respect to CuK α1.541 Å X-rays. Also, in the infrared absorption spectrum, 700~
Four absorption bands with the strongest intensity at 752±2cm ^-1 between 760cm ^-1 , two absorption bands with almost the same intensity between 1320 and 1340cm ^-1 , and a characteristic absorption band at 3288±2cm ^-1 There is.
However, 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.
The manufacturing method is complicated and difficult because it is manufactured by wet kneading at 180°C, preferably 60 to 130°C, for 5 to 20 hours. 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 stability of the properties of an electrophotographic photoreceptor is insufficient. Also known as a phthalocyanine compound is, for example, X-type metal-free phthalocyanine, which is described in Japanese Patent Publication No. 49-4338. This X-type metal-free phthalocyanine is CuK α1.541 as shown in Figure 4.
The black angle with respect to the X-ray of Å is 7.5, 9.1,
It has peaks at 16.7, 17.3, and 22.3. Also, USP
-3357989 shows its infrared absorption spectrum, and its characteristics are 746 cm ^-1 and 700 to 750 cm ^-1
It is shown that there are three peaks with equal intensity at 1318 cm ^-1 and 1330 cm ^-1 in between. However, this X-type metal-free phthalocyanine is relatively easier to manufacture than the above-mentioned τ-type metal-free phthalocyanine, and has crystal stability and potential stability for repeated use when used as a carrier generating material for electrophotographic photoreceptors. Although the performance is excellent, it is still insufficient. Problems to be Solved by the Invention As described above, phthalocyanine compounds are examples of organic carrier-generating substances that are sensitive in the long wavelength range, but τ-type metal-free phthalocyanine is repeatedly used in its manufacturing method and as an electrophotographic photoreceptor. There is a problem in the potential stability when the metal-free phthalocyanine is used, and there is room for improvement in the potential stability of the X-type metal-free phthalocyanine, except for the manufacturing method. Therefore, a first object of the present invention is to provide an electrophotographic photoreceptor using a metal-free phthalocyanine with high crystal stability. A second object of the present invention is to provide an electrophotographic photoreceptor that has high potential stability even after repeated use. A third object of the present invention is to provide an electrophotographic photoreceptor using metal-free phthalocyanine that is easy to manufacture. A fourth object of the present invention is to provide an electrophotographic photoreceptor that has the above-mentioned characteristics and is suitable for long wavelength range semiconductor lasers. Means for Solving the Problems In order to solve the above problems, the present invention
The Bragg angle for the X-ray of CuK α 1.541Å is
It has an X-ray diffraction spectrum with main peaks at 7.7, 9.3, 16.9, 17.6, 22.4, and 28.8, and the intensity ratio of the peak at a Bragg angle of 16.9 to the peak at a Bragg angle of 9.3 in this X-ray diffraction spectrum is 0.8.
~1.0, and the intensity ratio of each peak at bragg angles 22.4 and 28.8 to the peak at bragg angle 9.3 is 0.4 or more, and 700 to 760
cm ^-1 , has an infrared absorption spectrum with peaks at 1320 ± 2 cm ^-1 and 3288 ± 3 cm ^-1 , and has a peak at 700 to 760 cm
There are four peaks in ^{the -1} absorption band, of which
The present invention provides an electrophotographic photoreceptor characterized by containing a metal-free phthalocyanine having the strongest absorption peak at 720±2 cm ^-1 . Next, the present invention will be explained in detail. When the metal-free phthalocyanine of the present invention is used as a functionally separated electrophotographic photoreceptor, it is used as a carrier generating material and is combined with a carrier transporting material to form the photoreceptor.
This metal-free phthalocyanine in the present invention is different from either the above-mentioned τ-type metal-free phthalocyanine or X-type metal-free phthalocyanine, and
As shown in Figure 1, the Bragg angle for X-rays of CuK α 1.541Å (error 2Θ±0.2 degrees) is 7.7,
It has an X-ray diffraction spectrum with main peaks at 9.3, 16.9, 17.6, 22.4, and 28.8, and the Bragg angles of CuK α 1.541 Å of the τ-type metal-free phthalocyanine with respect to the X-ray are 7.6, 9.2, 16.8,
17.4, 20.4, 20.9, so the Bragg angle is 22.4,
It has a characteristic peak at 28.8 that is not found in the τ type. In addition, Cuk α of X-type metal-free phthalocyanine is 1.541
As mentioned above, the Bragg angle of Å with respect to X-rays is
7.5, 9.1, 16.7, 17.3, and 22.3, so it has a characteristic peak at a Bragg angle of 28.8 that is not found in the X-shape. Further, the Bragg angle of 9.3 in the X-ray diffraction spectrum of the metal-free phthalocyanine in the present invention is
The intensity ratio of the peak at a Bragg angle of 16.9 to the peak at a Bragg angle of 16.9 is 0.8 to 1.0, and the Bragg angle is 9.3
Since the intensity ratio of the peaks at Bragg angles of 22.4 and 28.8 to the peak of is 0.4 or more,
As is clear from Figure 4, the intensity ratio of the peak at a Bragg angle of 16.9 to the peak at a Bragg angle of 9.2, which corresponds to the former τ-type metal-free phthalocyanine, is
0.9 to 1.0, and unlike the latter, which does not have one Bragg angle, the intensity ratio cannot be determined, and as is clear from Figure 4, it corresponds to the former of type X metal-free phthalocyanine. The intensity ratio of the peak at a Bragg angle of 16.7 to the peak at a Bragg angle of 9.1 is 0.4 to 0.6, which is different from the latter case in which there is no peak corresponding to a Bragg angle of 28.8 and its intensity ratio cannot be determined. Furthermore, the infrared absorption spectrum of the metal-free phthalocyanine in the present invention is as shown in FIG.
It has four absorption bands between 700 and 760 cm ^-1 with the strongest at 720 ± 2 cm ^-1 and characteristic absorptions at 1320 ± 2 cm ^-1 and 3288 ± 3 cm ^-1 , and the τ-type metal-free phthalocyanine has the above-mentioned absorption bands. As shown, there are four absorption bands with the strongest absorption band between 700 and 760 cm ^-1 at 752±2 cm ^-1 , and one absorption band between 1320 and 1340 cm ^-1.
It is different from having two absorption bands instead of a book. Further, the metal-free phthalocyanine in the present invention is
It differs from the infrared absorption spectrum of type-free metal phthalocyanine in that it has a peak intensity of 700 to 760 cm ^-1 and has no absorption at 1330 cm ^-1 but a characteristic absorption at 3288±3 cm ^-1 . Furthermore, as shown in Figure 3, the visible and near-infrared absorption spectrum of the metal-free phthalocyanine in the present invention preferably has an absorption maximum at 770 nm or more and less than 790 nm.
It has an absorption maximum at ~820 nm, which is different from most that has an absorption maximum at about 790 nm. The metal-free phthalocyanine in the present invention is different from τ-type metal-free phthalocyanine and strain force (e.g. kneading)
An X-type metal-free phthalocyanine is obtained by milling with a solvent, and then this X-type metal-free phthalocyanine is subjected to a solvent treatment such as a dispersion treatment with a nonpolar solvent such as tetrahydrofuran. For milling with stirring or kneading, a dispersion medium commonly used for dispersing, emulsifying, or mixing pigments, such as glass beads, steel beads, alumina balls, flint stones, etc., is 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. When a solvent is required for stirring, kneading, grinding, etc., it is preferable to use a solvent that is liquid at the temperature at which these operations are being carried out. 1 selected from the group of diethylene glycol or polyethylene glycol solvents, cellosolve solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ketone solvents, ester ketone solvents, etc.
It is preferable to select more than one type of solvent. Representative examples of devices used in the above crystal transition step include general stirring devices, such as homomixers, dispersers, agitators,
There are stirrers, kneaders, Banbury mixers, ball mills, sand mills, attritors, etc. 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, for example, it can be done 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, transition to other crystal forms is less likely to occur, and this is better than the conventional τ type. Of course, it is better than the X type.
This makes it possible to manufacture the metal-free phthalocyanine of the present invention with less variation in quality, and further facilitates the manufacture as well as the above, and also makes it easier to manufacture when used in electrophotographic photoreceptors. Characteristics such as potential stability during repeated use can be improved. In the present invention, other carrier generating substances may be used in combination with the metal-free phthalocyanine. Examples of carrier generating substances that can be used in combination include α-type, β-type, γ-type, X-type, τ-type, τ′-type, η-type,
Examples include η′ type metal-free phthalocyanine. In addition, phthalocyanine pigments other than the above, azo pigments,
Examples include anthraquinone pigments, perylene pigments, polycyclic quinone pigments, methine squaritcate pigments, and the like. Examples of azo pigments include the following. (-5) A-N=N-Ar ₁ -C‖=CH-Ar ₂
-N=N-A (-6) A-N=N-Ar ₁ -C‖=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 this general formula, Ar ₁ , Ar ₂ and Ar ₃ are each a substituted or unsubstituted carbocyclic aromatic ring group, R ¹ , R ² , R ³ and R ⁴ are each an electron-withdrawing group a hydrogen atom, at least one of R ¹ to ^{R 4} is an electron-withdrawing group such as a cyano group,

【formula】

【formula】

【formula】

【formula】 or

【formula】 (X is a hydroxy group,

[Formula] or -NHSO ₂ -R ⁸ <However, R ⁶ and R ⁷ are each a hydrogen atom or a substituted or unsubstituted alkyl group, and R ⁸ 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, a carboxyl 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 ⁵ is a hydrogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a carboxyl group or an ester group thereof, A' is a substituted or unsubstituted aryl group, n is an integer of 1 or 2 , m is an integer from 0 to 4. )〕 Examples of polycyclic quinone pigments include compounds represented by the following general formula []. General formula [] (In this general formula, X' represents a halogen atom, a nitro group, a cyano group, an acyl group, or a carboxyl group, and n represents an integer of 0 to 4.) Specific examples are as follows. In the electrophotographic photoreceptor of the present invention, carrier transport substances used in the case of a functionally separated type include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiathiazole derivatives,
triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxazolone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, Examples include aminostilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like. Specifically, styryl compounds of the following general formula [] or [] can be mentioned. General formula [] (However, in this general formula, R ⁹ , R ¹⁰ : substituted or unsubstituted alkyl group,
Represents an R group, and substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group,
A halogen atom and an aryl group are used. Ar ⁴ : A substituted or unsubstituted aromatic ring group is used. Ar ⁵ : Represents a substituted or unsubstituted aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom,
Use an aryl group. R ¹¹ , R ¹² : substituted or unsubstituted aryl group,
Represents a hydrogen atom, and substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group,
A halogen atom and an aryl group are used. ) General formula (): (However, in this general formula, R ¹⁴ : substituted or unsubstituted aryl group, R ¹³ hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, amino group, substituted amino group, hydroxyl group, R ¹⁵ : represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group.) Specific examples of styryl compounds of the general formula [] or [] are as follows. Further, hydrazone compounds of the following general formulas [], [], [] or [] can also be used as carrier transport substances. General formula []: (However, in this general formula, R ¹⁶ and R ¹⁷ are hydrogen atoms or halogen atoms, respectively. R ¹⁸ and R ¹⁹ are each a substituted or unsubstituted aryl group, and Ar ⁶ is a substituted or unsubstituted arylene group. ) General formula []: (However, in this general formula, R ²⁰ : methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R ²¹ : methyl group, ethyl group, benzyl group, or phenyl group, R ²² : methyl group, ethyl group) group, benzyl group or phenyl group. General formula []: (However, in this general formula, R ²³ is a substituted or unsubstituted naphthyl group; R ²⁴ is a substituted or unsubstituted alkyl group, aralkyl group, or aryl group; R ²⁵ is a hydrogen atom, an alkyl group, or an alkoxy group; R ²⁶ and ^R27 represent the same or different groups consisting of a substituted or unsubstituted alkyl group, aralkyl group, or aryl group.) General formula []: (However, in this general formula, R ²⁸ : substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R ²⁹ : hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted aryl group, Q: represents a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group, an alkoxy group, or a cyano group; p: represents an integer of 0 or 1.) Specific examples of the hydrazone compounds of these general formulas [] to [] are as follows. That's right. Furthermore, a pyrazoline compound of the following general formula [] can also be used as a carrier transport substance. General formula []: [However, in this general formula, l: 0 or 1, R ³⁰ , R ³¹ and R ³² : substituted or unsubstituted aryl group, R ³³ and R ³⁴ : hydrogen atom, number of carbon atoms 1 to 4
an alkyl group, or a substituted or unsubstituted aryl group or aralkyl group (however, both R ³³ and R ³⁴ are not hydrogen atoms, and
When is 0, R ³³ is not a hydrogen atom. )] Specific examples of this pyrazoline compound are as follows. Furthermore, amine derivatives of the following general formula [] can also be used as carrier transport materials. General formula []: (However, in this general formula, Ar ⁷ , Ar ⁸ represent a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, a nitro group, or an alkoxy group is used as a substituent. Ar ⁹ : A substituted or unsubstituted phenyl group. It represents a phenyl group, a naphthyl group, an anthryl group, a fluorenyl group, a heterocyclic group, and substituents include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group,
Aryloxy group, aryl group, amino group,
Nitro groups, piperidino groups, morpholino groups, naphthyl groups, anthryl groups and substituted amino groups 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. ] Specific examples of this amine derivative are as follows. In order to constitute the photosensitive layer of the electrophotographic photoreceptor of the present invention, a layer in which the carrier-generating substance described above is dispersed in a binder may be provided on a conductive support. Alternatively, the carrier-generating substance and the carrier-transporting substance may be combined to provide a so-called functionally separated photosensitive layer of a laminated type or a dispersed type. When using a functionally separated photosensitive layer, it is usually shown in Figures 5 to 10.
Do as shown. That is, the layer structure shown in FIG. 5 forms a carrier generation layer 2 containing metal-free phthalocyanine according to the present invention on a conductive support 1,
A photosensitive layer 4 is formed by laminating a carrier transport layer 3 containing the above-mentioned carrier transport substance on this, and FIG. 6 shows a photosensitive layer 4' in which these carrier generation layer 2 and carrier transport layer 3 are reversed. In the layer structure shown in FIG. 7, an intermediate layer 5 is provided between the photosensitive layer 4 and the conductive support 1 having the layer structure shown in FIG. 5, and in FIG. 8, the layer structure shown in FIG. An intermediate layer 5 is provided between the photosensitive layer 4' and the conductive support 1 to prevent injection of free carriers into the conductive support 1, and the layer structure shown in FIG. 9 is based on the present invention. A carrier transport substance 6 mainly containing metal-free phthalocyanine and a carrier transport substance 7 which is also combined with the same.
In the layer structure shown in FIG. 10, the intermediate layer 5 described above is provided between the photosensitive layer 4'' and the conductive support 1. In the case of forming a photosensitive layer having a two-layer structure, the carrier generation layer 2 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 a carrier generation layer or a carrier transport layer, any binder can be used, but in particular, polymers that are hydrophobic, have a high dielectric constant, and have the ability to form an electrically insulating film are used. Polymers are 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 may be used alone or in a mixture of two or more of them. It can be used as Also, the ratio of carrier-generating substances to binder is 10 to 200.
% by weight, preferably 20-100% by weight, carrier transport material 10-500% by weight. The thickness of the carrier generation layer 2 thus formed is preferably 0.01 to 20 μm, more preferably 0.05 to 5 μm. The thickness of the carrier transport layer is 2 to 100 μm, preferably 5 to 30 μm. When the photosensitive layer is formed by dispersing the carrier-generating substance, the carrier-generating substance is preferably in the form of powder having an average particle size of 2 μm or less, preferably 1 μm or less. 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. In some cases, discharge may occur at the protruding parts of the particles, or Toner particles tend to adhere there, causing a toner filming phenomenon. For carrier-generating substances that are sensitive to long wavelength light (~700 nm), the surface charge is neutralized by the generation of thermally excited carriers within the carrier-generating substance, and if the particle size of the carrier-generating substance is large, this It seems to have a large neutralizing effect. Therefore, high resistance and high sensitivity can only be achieved by reducing the particle size. Further, the photosensitive layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use. 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. Further, the addition ratio of the electron-accepting substance is carrier-generating substance:electron-accepting substance in a weight ratio of 100:0.01 to 200, preferably 100:0.1 to 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, vapor deposition, or evaporation. By means such as lamination, paper,
A material provided on a substrate such as plastic film is used. The intermediate layer functioning as an adhesive layer or barrier layer may be made of a polymer as explained above as the binder resin, an organic polymer substance such as polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, or aluminum oxide. is used. The electrophotographic photoreceptor of the present invention is obtained as described above, and its feature is that the maximum value of the photosensitive wavelength range of the metal-free phthalocyanine used in the present invention is
Since it exists in the wavelength range of 770 nm or more and less than 790 nm, it is ideal as a photoreceptor for semiconductor lasers.As mentioned above, this metal-free phthalocyanine has an extremely stable crystal form, and transition to other crystal forms is unlikely to occur. It is. This is a great advantage not only in the production and properties of the metal-free phthalocyanine of the present invention described above, but also in the production and use of electrophotographic photoreceptors. Effects of the Invention As explained above, the present invention uses the metal-free phthalocyanine unique to the present invention, so that it is possible to obtain an electrophotographic photoreceptor having a wavelength range optimal for light in the long wavelength range, particularly semiconductor lasers. can. Also,
The metal-free phthalocyanine according to the present invention intentionally does not require a grinding aid when producing it, so it not only eliminates the need to remove it, but also does not require temperature control and can be processed at room temperature. , easy to manufacture. It also has excellent crystal stability against solvents, heat, and mechanical strain, and has excellent sensitivity and potential stability as an electrophotographic photoreceptor. Examples Examples will be described below, but first, examples of synthesis of a metal-free phthalocyanine according to the present invention and a synthesis example of a τ-type metal-free phthalocyanine as a comparative example will be shown. Synthesis Example 1 50 g of lithium phthalocyanine is added to 600 ml of concentrated sulfuric acid that has been thoroughly stirred at 0°C. The mixture is then stirred at this temperature for 2 hours. The resulting solution is 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 is filtered and the resulting mass is washed with water until neutral. The mass is then finally washed several times with methanol and dried in air. This dried powder is extracted with acetone in a 24 hour continuous extractor and dried in air to give a blue powder. In the above the precipitation is repeated to ensure a salt residue for lithium. In this way
30.5 g of blue powder was obtained. The X-ray diffraction pattern of the obtained product was consistent with the X-ray diffraction pattern of α-type metal-free phthalocyanine described in previously published materials. 30 g of α-type metal-free phthalocyanine thus obtained was placed in a 900 ml porcelain ball mill half-filled with 13/16 inch diameter balls.
Milling was performed for 164 hours at approximately 80 rpm. Thereafter, 200 ml of tetrahydrofuran was added into the ball mill, and milling was carried out again at room temperature for 24 hours. After removing the organic solvent from the dispersion after milling and drying, 28.2 g of the metal-free phthalocyanine according to the present invention was obtained.
I got it. The X-ray diffraction pattern of this metal-free phthalocyanine is
The infrared absorption spectrum was as shown in Fig. 2, and the visible near-infrared absorption spectrum was as shown in Fig. 3. Note that a film formed on a polyester film was used as a sample for the visible and near-infrared absorption spectrum.
The binder at this time was polymethyl methacrylate (Elvacite 2010, manufactured by Dupont). Synthesis Example 2 α-type metal-free phthalocyanine (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 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 room temperature for 10 minutes. Next, the α-type metal-free phthalocyanine purified above was placed in a sand mill together with a grinding aid and a dispersant, and kneaded at a temperature of 100±20° C. for 15 to 25 hours.
After confirming that the crystal form has changed to the τ type by this operation, take it out from the container, thoroughly remove the grinding aid and dispersant with water and methanol, etc., and dry it to form a τ type with a clear bluish tinge. Blue crystals of metal phthalocyanine were obtained. This was confirmed by the fact that the X-ray diffraction pattern matched that of the τ type shown in FIG. Example 1 1.0 g of the metal-free phthalocyanine obtained in Synthesis Example 1 and 2.0 g of polymethyl methacrylate were added to 100 ml of 1,2-dichloroethane and dispersed by ultrasonic dispersion on a conductive support made of polyester film deposited with aluminum. do. This dispersion was coated and dried so that the film thickness after drying was 0.5 μm to form a carrier generation layer. Further, on top of this, a solution of 12.4 g of the carrier transport material of Example V-2 shown in Table 1 and 16.5 g of polycarbonate (Panlite L-1250, manufactured by Teijin Chemicals) dissolved in 100 ml of 1,2-dichloroethane was dried. A carrier transport layer was formed by coating and drying so that the final film thickness was 12 μm, and an electrophotographic photoreceptor was obtained. Examples 2 and 3 Electrophotographs of Examples 2 and 3 were prepared in the same manner as in Example 1, except that the substances listed in the columns corresponding to Examples 2 and 3 in Table 1 were used as carrier transport materials. A photoreceptor for use was obtained. Comparative Example 1 In Example 1, the τ-type phthalocyanine obtained in Synthesis Example 2 was used instead of the metal-free phthalocyanine obtained in Synthesis Example 1, and the substance listed in the column corresponding to Comparative Example 1 was used as the carrier transport substance. An electrophotographic photoreceptor of Comparative Example 1 was obtained in the same manner except that . Comparative Example 2 In Example 1, ε-type copper phthalocyanine (Lionol Blue ES, manufactured by Toyo Ink Mfg. Co., Ltd.) was used instead of the metal-free phthalocyanine obtained in Synthesis Example 1, and the column of Comparative Example 2 was used as a carrier transport material. An electrophotographic photoreceptor of Comparative Example 2 was obtained in the same manner except that the substances described above were used. Evaluation Test Each of the electrophotographic photoreceptors obtained as described above was tested using an "electrometer SP428 model".
(manufactured by Kawaguchi Electric Seisakusho) to investigate its electrophotographic properties. In other words, the surface of the photoreceptor is charged with a voltage of -
Acceptance potential V _A () when charged at 6KV for 6 seconds
and the potential V ₁ after dark decay for 5 seconds (initial potential)
Exposure amount E1/2 required to attenuate by 1/2
(Lux・sec) (using tungsten light source) and dark decay rate (V _A − V _I )/V _I ×100% and 10 (Lux・sec)
The residual potential V _R () after exposure was measured. Next, in a similar measurement system, a tungsten light source is used as the light source, and the half-decreased exposure amount for light with a wavelength of 780 nm ± 1 nm, which is of particular concern, is measured through a monochromator.
E1/2 (λ=780) (erg/cm ² ) was measured. Also,
The acceptance potential V _A () and residual potential were also measured after 10,000 copies. Table 2 shows these results. In the table,
ΔV _A and ΔV _R are values obtained by subtracting the characteristic value after copying 10,000 times from the initial characteristic value.

【table】

【table】 [Brief explanation of the drawing]

Figure 1 is an X-ray diffraction diagram of the metal-free phthalocyanine according to the present invention, Figure 2 is its infrared absorption spectrum, Figure 3 is its near-infrared absorption spectrum, and Figure 4 is the X-ray of X-type and τ-type metal-free phthalocyanine. diffractogram,
FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, and FIG. 10 show specific examples of the layer structure of the electrophotographic photoreceptor of the present invention. In the figure, 1 is a conductive support, 2 is a carrier generation layer, 3 is a carrier transport layer, 4, 4', 4'' are photosensitive layers, 5 is an intermediate layer, 6 is a carrier generation material, and 7 is a carrier transport material. be.

Claims (1)

[Claims] 1 CuK α has an X-ray diffraction spectrum with main peaks at Bragg angles of 7.7, 9.3, 16.9, 17.6, 22.4, and 28.8 with respect to the X-ray of 1.541 Å, and this
The intensity ratio of the peak at a Bragg angle of 16.9 to the peak at a Bragg angle of 9.3 in the line diffraction spectrum is
0.8 to 1.0, and the intensity ratio of each peak at Bragg angles 22.4 and 28.8 to the peak at Bragg angle 9.3 is 0.4 or more, and 700 to
It has an infrared absorption spectrum with peaks at 760 cm ^-1 , 1320 ± 2 cm ^-1 and 3288 ± 3 cm ^-1 , and
An electrophotographic photoreceptor characterized by containing metal-free phthalocyanine, of which there are four peaks in the absorption band at 760 cm ^-1 , of which the peak at 720±2 cm ^-1 has the strongest absorption.