JP3230177B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a high-sensitivity photoreceptor effective for a printer, a copying machine, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Photoreceptors for an electrophotographic system include an inorganic photoreceptor containing an inorganic photoconductive substance such as selenium and cadmium sulfide as a main component and an organic photoreceptor containing various organic photoconductive compounds as a main component. They can be roughly classified. In the past, inorganic photoconductors with excellent sensitivity characteristics have been used for high-speed copiers, but in recent years, from the viewpoint of environmental protection, organic photoconductors that are harmless have great restrictions due to the toxicity of raw materials and product compounds. The demand for replacement is increasing. Based on such a trend, there is a strong demand for higher performance of the organic photoreceptor, and in particular, technology development for higher sensitivity is an urgent issue.

[0003] The most common method used for improving the performance of an organic photoreceptor is a function separation technique in which a charge generation function by light and a charge transport function are individually assigned to different substances. By allowing charge generation and charge transport to be performed by different substances, it became possible to select substances suitable for each substance from a wide range. In particular, organic photoconductors are rich in a variety of compounds, which is advantageous for high performance by such functional separation, and many charge generating substances (also referred to as carrier generating substances CGM) and charge transporting substances (also referred to as carrier transporting substance CTM). Has been proposed.

Examples of the charge generating substance of the organic photoreceptor include polycyclic quinone compounds represented by dibromance anthrone, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, bisazo compounds and trisazo compounds, and thiapyrylium compounds and polycarbonate. Eutectic complexes, squarium compounds and the like have been put to practical use. Further, as the charge transport material, for example, pyrazoline compounds, polyarylalkane compounds, triphenylamine compounds, hydrazone compounds, tetraphenylbenzidine compounds, styryl compounds, and the like have been put to practical use.

[0005] The performance of the charge generating material directly determines the sensitivity characteristics, but its basic function of absorbing incident light and generating charges depends on the molecular structure of the charge generating material. Not only is it significantly affected by the aggregate morphology of these molecules. For example, the above-mentioned metal-free phthalocyanine and titanyl phthalocyanine are known to have many crystal polymorphs.If the crystal structure is different even if the molecular structure is the same, the quantum efficiency of charge generation is completely different. Can be seen. X-type crystals and τ-type crystals of metal-free phthalocyanine show sensitivity one order higher than α-type and β-type crystals, and Y-type crystals of titanyl phthalocyanine have 3 to 4 times higher than A-type and B-type crystals. It is well known to exhibit twice the sensitivity. Similarly, the sensitivity of an azo compound or a squarium compound significantly changes due to the difference in the molecular aggregation structure.

As described above, in the development of a charge generating material, optimization of its crystal structure or molecular aggregation structure is an indispensable element as well as optimization of its chemical structure.

The general formula [I] or [I
The technology of using imidazole perylene compound of I) as a charge generating material was disclosed in Japanese Patent Publication No. 61-8423 (U.S. Pat. No. 3,972,717), and many electrophotographic photoreceptors using this compound as a charge generating material have been studied. I have. JP-A-59-59686 discloses a technique for preparing a photoreceptor by mainly dispersing and coating the present compound. JP-A-61-275848 (US Pat. No. 4,587,189), JP-A-63-180956, and Kaisho 63-2
JP-A-91061, JP-A-4-186363, and JP-A-4-186364 disclose techniques using the present compound in combination with a specific charge transporting substance. JP-A-64-56444, JP-A-4-20
No. 4850 discloses a technique of atomizing the present compound by acid paste treatment, and Japanese Patent Publication No. 63-41054 discloses a technique of sublimating and purifying a perylene-based compound containing the present compound.

However, in these prior arts, no study has been made on the crystal state of the present compound, so that sufficient sensitivity characteristics cannot be brought out, and it has not been possible to respond to the recent demand for higher sensitivity. .

Regarding the crystal form of the compound of the formula (I) or (II), several X-ray diffraction spectra are disclosed in J. Imag. Sci., Vol. 33, P151-159 (1989). . However, these are related to powder crystals, and in the study of the present inventors, when a photoreceptor coating solution was prepared using these powders, the photoreceptor coating solution depends on the conditions of preparation of the coating solution and the chemical purity. The X-ray diffraction spectrum of the product changes,
At the same time, it was found that the characteristics of the photoreceptor also changed significantly.

[0010] From such a viewpoint, Japanese Patent Application Laid-Open Nos. H5-249719 and H5-281769 disclose a technique for controlling the crystal state of the compound. These techniques adjust the crystal state by a dry grinding method.However, since such a dry grinding involves a strong local shearing force, there is a problem in homogenization of the grinding, and black spots appear on the electrophotographic image. There is a disadvantage that it is easy to occur. Further, in the dry pulverization, a crystal defect is easily introduced due to a large mechanical impact on the crystal powder, and as a result, the charge potential holding ability is reduced. Thus, the crystal control technology is still insufficient for this compound,
Its performance has not been exploited.

On the other hand, in the organic photoreceptors practically used up to now, negative charging is predominant, but negative charging by corona discharge generates ozone 5 to 10 times of positive charging, and high concentration ozone Deterioration becomes remarkable and there is a problem in durability.

Further, the ozone emission from the copying machine has become a problem in working environment hygiene due to an increase in the frequency of use, but as described above, the negative charging system has a large number of ozone generating layers in principle and is not suitable for environmental measures. Not fit.

Therefore, attention is paid to the positive charging system, but the conventional charge generating materials are still unsatisfactory in sensitivity, chargeability, ozone resistance, image quality and the like, and the same applies to the above-mentioned imidazole perylene compound.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to have a spectral sensitivity in a high sensitivity long wavelength region which can be widely used for high-speed copying machines, printers, faxes, etc. An object of the present invention is to provide an electrophotographic photosensitive member for positive charging, which is durable to an object or ultraviolet light and has excellent image stability.

[0015]

The object of the present invention is achieved by the following constitution.

1. In a positively charged electrophotographic photosensitive member having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, the charge generating substance is represented by the following general formula (I) or (II), and Bragg angle 2θ of X-ray diffraction spectrum with respect to Cu-Kα ray is 6.3 ± 0.2 °, 12.4 ± 0.2
°, a crystal having peaks at 25.3 ± 0.2 ° and 27.1 ± 0.2 °, having a maximum peak intensity at 12.4 ± 0.2 °, a half width of the peak is 0.65 or more, and a clear peak at 11.5 ± 0.2 °. perylene face charges having a crystal type that does not have a peak
In Oh I, the perylene pigment after the sublimation purification, Ashiddope
Positively chargeable electrophotographic photosensitive member, characterized in der Rukoto those strike process.

[0017]

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(In the formula, Z represents an atom group necessary for forming a substituted or unsubstituted heterocyclic ring.) 2. The electrophotographic photosensitive member for positive charging according to claim 1, wherein the average particle diameter of the charge generating substance is 1.0 μm or less.

3. 3. The electrophotographic photosensitive member for positive charging according to claim 1, wherein the photosensitive layer is a single layer and contains a charge generating substance and a charge transporting substance.

4. 3. The photosensitive layer according to claim 1, wherein the photosensitive layer is laminated on a substrate in the order of a charge transport layer containing at least a charge transport substance and a charge generation layer containing a charge generation substance.
The electrophotographic photoreceptor for positive charging according to the above item.

5. 5. The electrophotographic photosensitive member for positive charging according to claim 4, wherein the charge generation layer contains a charge transport material.

6. 6. The electrophotographic photosensitive member for positive charging according to claim 1, wherein a protective layer is provided on the photosensitive layer.

7. In a method for producing a positively charged electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, the charge generating substance contained in the photosensitive layer is represented by the following general formula (I) or Represented by (II) and Cu
-Bragg angle 2θ of X-ray diffraction spectrum for Kα ray
Are 6.3 ± 0.2 °, 12.4 ± 0.2 °, 25.3 ± 0.2 ° and 27.1 ± 0.
A crystal having a peak at 2 °, having a maximum peak intensity at 12.4 ± 0.2 °, a half-width of the peak being 0.65 or more, and having no clear peak at 11.5 ± 0.2 °. I perylene pigment der with, the perylene pigment
After the purification by sublimation state, and are intended to be acid paste treatment,
A method for producing a positively chargeable electrophotographic photoreceptor, comprising applying at least a photosensitive layer by applying a coating solution containing the charge generating substance using a circular amount-regulating type coating machine.

[0024]

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8. In a method for producing a positively charged electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, the charge generating substance contained in the photosensitive layer is represented by the following general formula (I) or Represented by (II) and Cu
-Bragg angle 2θ of X-ray diffraction spectrum for Kα ray
Are 6.3 ± 0.2 °, 12.4 ± 0.2 °, 25.3 ± 0.2 ° and 27.1 ± 0.
A crystal having a peak at 2 °, having a maximum peak intensity at 12.4 ± 0.2 °, a half-width of the peak being 0.65 or more, and having no clear peak at 11.5 ± 0.2 °. I perylene pigment der with, the perylene pigment
After the purification by sublimation state, and are intended to be acid paste treatment,
A method for producing a positively charged electrophotographic photoreceptor, comprising applying a coating solution containing the charge generating substance by spray coating to form at least a photosensitive layer.

[0026]

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(In the formula, Z represents a group of atoms necessary to form a substituted or unsubstituted heterocyclic ring.) 9. The method according to claim 7, wherein the photosensitive layer is a single layer and contains a charge generating substance and a charge transporting substance.

10. 9. The method according to claim 7, wherein a charge transport layer containing at least a charge transport material and a charge generation layer containing a charge generation material are laminated on the photosensitive layer in this order. .

As a method for preparing a crystal having an X-ray spectrum peculiar to the above-mentioned perylene pigment, a desired crystal can be obtained by selecting a dispersion method such as a dispersing solvent and dispersion strength in addition to crystal purification as described below. can get.

The crystal form of the imidazole perylene compound used in the present invention is described in J. Imag. Sci., Vol. 33, P151-
159 (1989) discloses four types of X-ray diffraction spectra called α, γ, ε, and ρ. Basically, α-type and ε-type have similar crystal structures, but it is clear that ρ-type is a completely different crystal. The crystal state of the present invention is based on this ρ-type crystal. The change in state that occurs in the step of dispersing and pulverizing the ρ-type crystal in an organic solvent has a significant effect on the sensitivity characteristics.

Generally, in order to obtain highly sensitive photoreceptor characteristics, first, it is necessary to obtain a fine and uniform coating film of a carrier generating substance. That is, the first important thing in the dispersion atomization step is to atomize the carrier generating substance.

When the crystallite size becomes smaller than a certain size due to dispersion atomization, broadening of a diffraction peak and reduction in peak intensity occur in an X-ray diffraction spectrum. The ρ-type crystal of the imidazole perylene compound is Cu
6.3 ± 0.2 in the X-ray diffraction spectrum for -Kα ray
The peaks at °, 12.4 ± 0.2 °, 25.3 ± 0.2 °, and 27.1 ± 0.2 ° are characteristic, but there is also a unique peak at 11.5 ± 0.2 °. Broadening of the entire peak can be seen as the ρ-type crystal is dispersed and atomized, but what is particularly important in the present invention is that the half value width of the peak at 12.4 ± 0.2 ° becomes 0.65 ° or more. However, the peak of 11.5 ± 0.2 ° is buried by the peak of 12.4 ± 0.2 ° thus broadened, and it is necessary that the peak of 11.5 ± 0.2 ° is not recognized. However, 12.4 ± 0.2 °
When the half-width of the peak of 1.5 exceeds 1.5 °, it cannot be said that the crystal is in a ρ-type crystal state.

The photoreceptor characteristics of the imidazole perylene compound of the present invention depend on the crystalline state characterized by the relative intensity of the peak in the X-ray diffraction spectrum. The imidazole perylene compound is 6.3 at the stage of synthesis.
The peak intensity around ° is often the maximum, and the sublimated peak intensity at 25-28 °
The peak intensity at 12.4 ° may be maximum. However, when these are dispersed and atomized in an organic solvent, the relative intensity of each peak changes, and thus the photoconductor characteristics change.
The crystal of the present invention can obtain particularly excellent sensitivity characteristics by maximizing the peak intensity at 12.4 ± 0.2 ° of the X-ray diffraction spectrum.

That is, in the present invention, 12.4 ± 0.2
The peak half-value width of ° is 0.65 ° or more, and 11.5 ± 0.
After pulverization to a state where no clear peak is shown at 2 °, a state where the peak intensity at 12.4 ± 0.2 ° is maximum is used.

In such a state, an excellent sensitivity effect and repetition stability can be obtained. The method for obtaining such a crystalline state of the carrier-generating substance is not particularly limited, but can be found in the dry pulverization method. The best way to prevent such defects in electrophotographic images is to subject the sublimated and purified imidazole perylene compound to acid paste treatment (amorphization or low crystallization) using sulfuric acid, and convert the imidazole perylene compound to an organic solvent with high affinity. It is intended to gently disperse with a polymer binder in the middle to make the crystal grow into a target crystal state while growing the crystal. In this method, uniform atomization is achieved, and a reduction in characteristics due to the introduction of crystal defects can be avoided due to a small mechanical impact.

The imidazole perylene compound of the general formula [I] or [II] can be synthesized by a dehydration condensation reaction of perylene-3,4,9,10-tetracarboxylic dianhydride with o-phenylenediamine. Preferred examples of Z include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyridine ring, a pyrimidine ring, a pyrazole ring, and an anthraquinone ring, and particularly preferred are a benzene ring and a naphthalene ring.

As the substituent for Z, alkyl, alkoxy, aryl, aryloxy, acyl, acyloxy,
Amino, carbamoyl, halogen, nitro, cyano and the like can be mentioned.

Next, the structure of a typical perylene pigment of the present invention is as follows.

[0039]

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The synthesized imidazole perylene compound is subjected to sublimation purification to remove impurities. The sublimation operation is repeated once to about 5 to 6 times, but it is preferable to repeat the sublimation operation two or more times. When a coating solution is prepared without performing sublimation purification, it is difficult to obtain the crystalline state of the present invention. The imidazole perylene compound obtained by sublimation shows a sharp peak pattern in the X-ray diffraction spectrum, confirming that the compound has a high crystallinity.

The imidazole perylene compound having a high crystallinity obtained by sublimation purification is converted to a state with a low crystallinity by performing an acid paste treatment using sulfuric acid. That is, after dissolving in concentrated sulfuric acid, the solution is poured into a poor solvent such as water or methanol to cause precipitation, and this is filtered and dried to obtain fine particles of low crystalline fine particles.

The low-crystalline powder after the acid paste treatment is subjected to a dispersion treatment in a solvent having a high affinity for the imidazole perylene compound using a suitable disperser. Examples of the solvent having a high affinity include a ketone solvent having 4 to 8 carbon atoms, a cyclic ether solvent having 4 to 7 carbon atoms, or a solvent having 2 carbon atoms.
Use of from 4 to 4 halogenated hydrocarbon solvents is useful. Among them, particularly preferred solvents include methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dichloroethane, and trichloroethane. In this dispersion treatment, good results can be obtained by the presence of an appropriate binder polymer.

Particularly preferred binder polymers include polyvinyl acetal resins such as polyvinyl butyral and polyvinyl formal, vinyl chloride-vinyl acetate resins, polyester resins, polycarbonate resins, acrylic resins and methacrylic resins, acrylic and methacrylic copolymer resins, silicone resins, Examples include silicone copolymer resin, polystyrene, styrene copolymer resin, phenoxy resin, phenol resin, urethane resin, epoxy resin and the like.

The specific crystalline state of the present invention is realized in the dispersion coating solution obtained by such a method. In this method, high purification by sublimation purification is important for the crystal state adjustment during dispersion, and this is further made amorphous by acid paste treatment with sulfuric acid. In the process of dispersion treatment, the amorphous state (or low crystalline state) is obtained. ), The crystal is grown by a specific solvent effect, whereby the specific crystal state of the present invention can be stably obtained from a completely different viewpoint.

A photoreceptor is prepared using the obtained dispersion coating solution. Whether or not the crystalline state of the present invention is realized in the photoconductor is determined by the X of the perylene compound peeled from the photoconductor.
It can be confirmed by measuring a line diffraction spectrum. Since no change in the crystal state occurs in the process of coating the photoreceptor, it can be confirmed by removing the solvent from the dispersion coating solution and measuring the X-ray diffraction spectrum.

These samples are measured by a powder X-ray diffractometer using Cu-Kα radiation as an X-ray source, and a diffraction line intensity distribution is obtained as a function of the Bragg angle 2θ. At this time, when the sample amount is sufficient, the relative intensity ratio between the peak intensities does not change depending on the sample amount, but as the sample amount decreases, the peak intensity on the low angle side relatively increases. Therefore, in the measurement, a sufficient amount of the sample must be used so that the peak intensity ratio does not change with the sample amount.

The peak intensity here is, as shown in FIG. 4, the intersection d of the line segment connecting the rising points a and b from the baseline level including noise and the perpendicular drawn from the vertex c.
Is defined as the height up to the vertex c (the length of the line segment cd) with respect to. The half width of the peak is defined as the peak width at a position of cd / 2 height from the point d.

As the binder used together with these perylene pigments, in addition to bisphenol A type polycarbonate, JP-A-60-172045, pages 4-5, JP-A-5-25729.
No. 9, pages 5 to 9 or Japanese Patent Application No. 5-88813, pages 18 to 24, polycarbonates are advantageously used.

As other binders, for example, the following can be mentioned.

(1) Polyester (saturated polyester,
(2) methacrylic resin (3) acrylic resin (4) polyvinyl chloride (5) polyvinylidene chloride (6) polystyrene (7) polyvinyl acetate (8) styrene copolymer resin (for example, styrene-butadiene copolymer) (9) Acrylonitrile copolymer resin (eg, vinylidene chloride-acrylonitrile copolymer, etc.) (10) Vinyl chloride-vinyl acetate copolymer (11) Vinyl chloride-vinyl acetate-maleic anhydride copolymer (12) Silicone resin (13) Silicone-alkyd resin (14) Phenol resin (for example, phenol-formaldehyde resin, cresol-formaldehyde resin, etc.) (15) Styrene-alkyd resin (16) Poly-N-vinyl carbazole (17) Polyvinyl butyral (1 8) Polyvinylformal (19) Polyhydroxystyrene The charge transporting substance (CTM) usable in the present invention is not particularly limited, and examples thereof include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, and imidazole. Derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazine compounds, pyrazoline compounds, amine derivatives, oxazolone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, amino Stilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene and the like. As the CTM used in the present invention, a CTM which has an excellent ability to transport holes generated at the time of light irradiation to the support and which is suitable for combination with the perylene derivative of the present invention is used.

As the CTM that is preferably used,
Compounds described on pages 26 to 68 of 5-88813 are preferred.

More preferably, JP-A-4-186363, pages 4 to 6
Monostyryl compounds described on pages 4 to 6 of JP-A-4-186364 and styryl compounds described on pages 8 to 18 of JP-A-5-158265 are preferred.

CTM is applied by dissolving and dispersing at least one or more of them together with the binder resin described above.
It can be formed by drying.

The perylene pigment of the present invention utilizes its excellent charge generating ability, uses it as a charge generating substance (CGM), and uses a CTM which can work effectively in combination with the CGM to provide a so-called functional separation. Type photoreceptor. The function-separated type photoreceptor may be a mixed dispersion type of the above two substances, or a charge generation layer (CGL) containing a CGM comprising the perylene derivative of the present invention and a charge transport layer (CTL) are laminated. A stacked photoconductor may be used.

Further, the electrophotographic photoreceptor of the present invention comprises
As described in JP 11472 or JP-A-5-80564, spectral sensitivity and copy reproducibility can be improved by using a mixed crystal of titanyl phthalocyanine / vanadyl phthalocyanine or a polycyclic quinone compound. The mixing ratio between the perylene pigment and these compounds is 0.2: 99.8 to 90:10
It is more preferably 0.5: 99.5 to 80:20 (weight ratio).

The layer structure of the electrophotographic photoreceptor of the present invention may be a single layer type, a CTL / CGL / substrate type in which a charge transport layer (CTL) is superposed on a charge generation layer (CGL), or the reverse configuration. Any of a certain CGL / CTL / substrate type lamination type can be constituted, but a single-layer type and CGL / CTL / substrate type are convenient because it is difficult to obtain a high-performance n-type CTM.

The electrophotographic photoreceptor of the present invention comprises a CGM on a support 1 (a conductive support or a sheet provided with a conductive layer) as shown in FIGS. 1 (1) to (4). , C
A single-layered PCL 2 containing a TM and a binder resin is provided. As shown in (5) to (8) of FIG. 1, a PCL having a laminated configuration in which a CTL 5 is a lower layer on a support 1 and a CGL 6 is an upper layer. Are provided.

In a function-separated type photoreceptor having a single-layer structure, a single layer generates and transports electric charge by light, and the CGM and the CTM are electrically connected in the layer, or the CGM is also charged. It contributes to transportation.

In any of the layer configurations, the photosensitive layer (PC
L), a protective layer may be provided on top of the support and PCL.
An undercoat layer (intermediate layer) having a barrier function and adhesiveness may be provided therebetween. It is preferable to add CTM to the single-layer PCL and the function-separated CGL as necessary. CTM
The amount of addition is 1 to the binder resin of CGL.
200 wt% is preferred.

The thickness of the single-layer PCL is preferably 10 to 60 μm. Function-separated CGL film thickness is 0.5 to 30 μm
It is preferred that Further, the thickness of the CTL is preferably 10 to 60 μm.

The thickness of the surface protective layer is preferably 0.1 to 10 μm. The thickness of the intermediate layer is preferably 0.05 to 20 μm.

As the binder resin usable for the protective layer and the intermediate layer, for example, polystyrene, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin,
Epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, phenoxy resin, polyarylate, polycarbonate resin, silicone resin, addition polymerization type resin such as melamine resin, polyaddition type resin,
Polycondensation type other resins, and copolymer resins containing two or more of repeating units of these resins, for example, vinyl chloride
-In addition to insulating resins such as vinyl acetate-maleic anhydride copolymer resin, polymer organic semiconductors such as poly-N-vinyl carbazole are exemplified.

As a method for coating the photosensitive layer used in the present invention, any coating method such as dipping, spraying, blade, or roll method may be used. Preferably, JP-A-58
Preferred is a coating method with a circular amount control described in JP-A-189061, JP-A-4-267260, and a spray coating method described in JP-A-4-321050.

Next, as the conductive support for supporting the PCL, a metal plate such as aluminum or nickel, a metal drum or a metal foil laminated, or a plastic film on which aluminum, tin oxide, indium oxide or the like is deposited, or a conductive film is used. A film or a drum made of paper, plastic, or the like coated with a conductive material can be used.

In the present invention, the PCL is prepared by adding the above-mentioned perylene derivative of the present invention to an appropriate dispersion medium or solvent alone or together with at least the above-mentioned binder resin, for example, in a ball mill, a homomixer, a sand mill, an ultrasonic disperser, an attritor or the like. It can be provided by a method in which a dispersion liquid dispersed by a disperser is applied onto a support or an undercoat layer or CTL and dried.

The average particle size of the dispersed CGM particles is 1.0 μm or less,
Preferably, it is 0.01 to 0.5 μm. More preferably 0.05 to
0.3 μm.

The dispersion medium used in the present invention includes, for example, hydrocarbons such as hexane, benzene, toluene and xylene; methylene chloride, methylene bromide, 1,2-
Halogenated hydrocarbons such as dichloroethane, sym-tetrachloroethane, cis-1,2-dichloroethane, 1,1,2-trichloroethane, 1,2-dichloropropane, chloroform, bromoform, chlorobenzene; acetone, methyl ethyl ketone, cyclohexanone Ketones such as ethyl acetate, butyl acetate and the like: alcohols such as methanol, ethanol, propanol, butanol, cyclohexanol, heptanol, ethylene glycol, methyl cellosolve, ethyl cellosolve, cellosolve acetate and derivatives thereof; tetrahydrofuran Ethers and acetals such as 1,4-dioxane, furan and furfural; amines such as pyridine, butylamine, diethylamine, ethylenediamine and isopropanolamine; amides such as N, N-dimethylformamide Containing compound, other fatty acids and phenols, sulfur, such as carbon disulfide and triethyl phosphate may be used alone or in combination of two or more of such phosphorus compounds.

In the PCL of the present invention, an antioxidant can be added for the purpose of preventing ozone deterioration.

Typical examples of such antioxidants are shown below, but are not limited thereto.

Group (1): hindered phenols dibutylhydroxytoluene, 2,2'-methylenebis (6-t
-Butyl-4-methylphenol), 4,4'-butylidenebis
(6-t-butyl-3-methylphenol), 4,4'-thiobis (6-
t-butyl-3-methylphenol), 2,2'-butylidenebis
(6-t-butyl-4-methylphenol), α-tocophenol, β-tocophenol, 2,2,4-trimethyl-6-hydroxy-7-t-butylchroman, pentaerythyltetrakis [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], butylhydroxyanisole , Dibutylhydroxyanisole, 1- [2-{(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionyloxy] -2,
2,6,6-tetramethylpiperidyl and the like.

Group (2): paraphenylenediamines N-phenyl-N'-isopropyl-p-phenylenediamine,
N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-t-butyl-p -Phenylenediamine.

Group (3): hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl
-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone and the like.

Group (4): Organophosphorus compounds dilauryl-3,3'-thiodipropionate, distearyl-3-3'-thiodipropionate, ditetradecyl-3,
3'-thiodipropionate and the like.

These compounds are known as antioxidants for rubbers, plastics, fats and oils, and commercially available products can be easily obtained.

[0075] These antioxidants may be added to any of CGL, CTL and the protective layer. In this case, the amount of the antioxidant added is 0.0 with respect to 100 parts by weight of the binder resin.
The amount is from 05 to 200 parts by weight, preferably from 1 to 50 parts by weight, particularly preferably from 2 to 25 parts by weight.

In the present invention, one or more electron accepting substances can be contained in CGL for the purpose of improving sensitivity, reducing residual potential and reducing fatigue during repeated use, and the like. Specific substances are described in JP-A-5-6015, page 8.

The electrophotographic photoreceptor containing the perylene derivative according to the present invention can respond favorably to visible light and near-infrared light, but particularly has an absorption maximum at a wavelength of about 400 to 700 μm. I have.

As a light source having such a wavelength, a halogen lamp, a fluorescent lamp, a tungsten lamp or the like is generally used.

[0079]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention.

In the description, “parts” means “parts by weight”.

(Synthesis Example) 39.2 g of perylene-3,4,9,10-tetracarboxylic dianhydride, 32.4 g of o-phenylenediamine,
800 ml of α-chloronaphthalene was mixed and reacted at 260 ° C. for 6 hours. After cooling, the precipitated crystals were collected by filtration and washed repeatedly with methanol. By heating and drying, Exemplified Compound A-1 was obtained.

(Sublimation Example) The exemplified compound A-1 obtained in the above synthesis example was purified by sublimation under a heating condition of 500 ° C. under a pressure of 5 × 10 ^{−4 to} 5 × 10 ⁻³ torr. Volatile impurities were removed using a shutter. The purified crystals obtained were purified once more by the same sublimation treatment.
A product that has been subjected to two sublimation operations in this manner is referred to as a sublimated product (SUB product) of Exemplified Compound A-1.

(Example of Acid Paste Treatment) A solution prepared by dissolving 20 g of the sublimation product of Exemplified Compound A-1 in 600 ml of concentrated sulfuric acid was filtered through a glass filter, and then dropped into 1200 ml of pure water to precipitate. This was collected by filtration, washed thoroughly with pure water, and dried. What was obtained in this manner was used as Exemplified Compound A-
No. 1 acid paste processed product (AP product).

(Preparation of Photoconductor 1) Charge Transport Material T-1
75 parts and 100 parts of polycarbonate resin "Iupilon Z200" (weight average molecular weight 52,000) (Mitsubishi Gas Chemical Co., Ltd.)
-A solution dissolved in 500 parts of dichloroethane is applied on an aluminum substrate by a dip coating method, and after drying, the film thickness is 20 μm.
Was formed.

Next, polyester resin Byron 200
6 parts (manufactured by Toyobo Co., Ltd.) are dissolved in 500 parts of methyl ethyl ketone, and 1.5 parts of an AP product of Exemplified Compound A-1 obtained by the method described above as a charge generating substance and 4.5 parts of T-1 as a charge transport substance are added. Dispersion was performed with a sand mill for 15 hours together with 2000 parts of glass beads having a diameter of 1 mm to obtain a dispersion liquid 1.

The dispersion obtained at this time was applied on a glass plate a plurality of times and dried to form a dry film having a thickness of about 200 μm, and the X-ray diffraction spectrum was measured using Cu-Kα rays. When the Bragg angle 2θ was 6.3 ± 0.2 °, 1
Peaks at 2.4 ± 0.2 °, 25.3 ± 0.2 °, and 27.1 ± 0.2 °, with a maximum peak intensity at 12.4 ± 0.2 °, a half-width of the peak of 0.65 or more, and a clear peak at 11.5 ± 0.2 ° Was not shown. Further, the average particle diameter was measured by an electron micrograph, and was 0.06 μm.

FIG. 2 shows an X-ray diffraction spectrum (XRD) using the dispersion 1.

The dispersion was dip-coated on the charge transport layer and dried to form a 5 μm-thick charge generation layer.
Photoconductor 1 of the present invention was obtained.

(Preparation of Photoreceptor 2) 100 parts of polycarbonate resin Iupilon Z200 (manufactured by Mitsubishi Gas Chemical Co., Ltd.) is dissolved in 500 parts of 1,2-dichloroethane, and further an exemplary compound obtained by the above-mentioned method as a charge generating substance. AP product of A-1
20 parts were added, and the mixture was dispersed in a sand mill for 15 hours together with 2500 parts of glass beads having a diameter of 1 mm. Photoconductor 2 of the present invention was obtained in the same manner as photoconductor 1, except that CGL was formed using the dispersion 2 with a circular amount-regulating coating machine.

When the X-ray diffraction spectrum of the dispersion 2 was measured in the same manner as in the case of the dispersion 1, as shown in Table 1, the dispersion had the maximum peak intensity at 12.4 ± 0.2 ° and the half width of the peak. Was 0.94 °, and no clear peak was observed at 11.5 ± 0.2 °. The average particle size of the charge generating substance was measured in the same manner as in the case of the photoreceptor 1, and found to be 0.3 μm.

(Preparation of Photoreceptor 3) Dispersion 3 was obtained by changing the solvent of dispersion 2 to tetrahydrofuran, and further dispersing the glass beads in a sand mill at 1500 parts for 10 hours to obtain dispersion 3. Photoconductor 3 of the present invention was obtained in the same manner as photoconductor 2 except for using it.

When the X-ray diffraction spectrum of the dispersion 3 was measured in the same manner as in the case of the photoreceptor 1, as shown in Table 1, the dispersion 3 had a maximum peak intensity at 12.4 ± 0.2 ° and the half width of the peak was 0.68 °, indicating that there was no clear peak at 11.5 ± 0.2 °. The average particle size of the charge generating substance was measured in the same manner as in the case of the photoreceptor 1.
μm.

(Preparation of Photoconductor 4) Charge Transport Material T-2
75 parts, 100 parts of polycarbonate resin "Iupilon Z200" (weight average molecular weight 52,000) (manufactured by Mitsubishi Gas Chemical), 10 parts of polyester resin "Byron 200" (manufactured by Toyobo) and a small amount of silicone oil "KF-54" (Shin-Etsu A solution in which 500 parts of 1,2-dichloroethane was dissolved was applied on an aluminum drum by a dip coating method, and after drying, a charge transport layer having a thickness of 25 μm was formed.

Next, the exemplary compound A-
15 parts and 1 part of a polyvinyl butyral resin "ESLek BL-S" (manufactured by Sekisui Chemical Co., Ltd.) as a binder resin were dispersed together with 200 parts of methyl ethyl ketone using a sand mill to obtain a dispersion liquid 4. The dispersion 4 was applied using a circular amount-regulating coating machine, and after drying, a charge generation layer having a thickness of 0.5 μm was formed. Further, a surface protective layer was formed thereon. The photoreceptor of the present invention thus obtained is referred to as photoreceptor 4.

The X-ray diffraction spectrum of the dispersion 4 was measured in the same manner as in the case of the dispersion 1, and the spectrum was the same as that of the dispersion 1. The average particle size of the charge generation material was 0.05 μm.

(Preparation of Photoreceptor 5) The photosensitive material of the present invention was prepared in the same manner as in Photoreceptor 1 except that the charge transporting material of the charge transport layer of the photoreceptor 1 was changed to Compound T-2, and Dispersion 1 was applied by spraying. Body 5 was obtained.

(Preparation of Photoreceptor 6) A photosensitive layer was formed on an aluminum substrate using the dispersion liquid 2 by a circular amount-regulating type coater, and after drying, a photoreceptor 6 of the present invention having a thickness of 25 μm was obtained. .

(Preparation of Photoreceptor 7) The ultrasonic dispersion method was used instead of the sand mill, which is a means for dispersing the dispersion 1,
A dispersion 5 was obtained in the same manner as the dispersion 1 except that the dispersion was performed for a time. Photoconductor 7 (Comparative Example 1) was obtained in the same manner as Photoconductor 1, except that Dispersion 5 was used.

When the X-ray diffraction spectrum of the dispersion 5 was measured in the same manner as in the case of the photoreceptor 1, as shown in Table 1, the peak intensity of 12.4 ± 0.2 was the maximum and the half width of the peak was In addition to 0.60 °, a clear peak was found at 11.5 ± 0.2. The average particle size of the charge generating substance measured in the same manner as that of the photoreceptor 1 was 1.2 μm.

(Preparation of Photoreceptor 8) Dispersion was carried out in the same manner as in Dispersion Liquid 1 except that Sublimation of Exemplified Compound A-1 (SUB product) was used instead of AP product of Exemplified Compound A-1 of Dispersion 1. Liquid 6 was obtained. Photoconductor 8 (Comparative Example 2) was obtained in the same manner as photoconductor 1, except that dispersion 6 was used.

When the X-ray diffraction spectrum of the dispersion 6 was measured in the same manner as in the case of the photoreceptor 1, as shown in Table 1, it did not have the maximum peak intensity at 12.4 ± 0.2 °,
It was found that the peak intensity was maximum at ± 0.2 °, and the half-width of the peak at 12.4 ± 0.2 ° was 0.68 °, with no clear peak at 11.5 ± 0.2 °. The XRD diagram is shown in FIG. Further, the average particle size of the charge generating substance was measured in the same manner as in the case of the photoreceptor 1, and it was 1.5 μm.

[0102]

[Table 1]

(Preparation of Photoconductor 9) Photoconductor 9 and Example 7 were obtained in the same manner as in Photoconductor 2 except that the CGL was changed to the dip coating method.

[0104]

[Table 2]

[0105]

Embedded image

Evaluation of Examples 1, 2, 3, 4, 5 and 6 and Comparative Examples 1 and 2 Photoconductors Nos. 1 to 8 obtained as described above were used in a corrector of Konica copier U-BIX 2028. Attached to the charging remodeling machine, a real copy test of 10,000 copies was performed in a high temperature and high humidity environment (30 ° C., 80% RH).

Table 3 shows changes in the characteristics and image quality of the photosensitive member at the initial stage and after 10,000 copies.

[0108]

[Table 3]

It can be seen that the photoreceptor of the present invention has excellent image quality stability when copying a large number of sheets.

Evaluation method of image quality <Image fog and image density> Image density was measured with a reflection densitometer.

(Evaluation criteria)

[0112]

[Table 4]

<Image white spots> The image analysis device "Omni-Con
The size and number of image white spots were measured using "3000 type" (manufactured by Shimadzu Corporation).

(Evaluation criteria)

[0115]

[Table 5]

<Fine Line Reproducibility> Using a chart provided with 8 equally spaced horizontal lines / mm in accordance with JIS Z4916, up to three generations were copied and visually judged whether discrimination was possible.

(Evaluation criteria)

[0118]

[Table 6]

<Re-evaluation of Examples 2, 4, 5 and 7> Photoconductors Nos. 2, 4, 5 and 9 obtained as described above were used in a positive charging remodeling machine of Konica copier U-BIX2028. It was mounted and subjected to a 50,000-copy live-action test in a normal temperature and normal humidity environment (20 ° C., 50% RH). Table 7 shows the change in image quality.

[0120]

[Table 7]

As is evident from Table 7, it is understood that the image quality of the halftone portion is improved by using the circular amount-regulating coating machine or the spray coating machine.

[0122]

Industrial Applicability According to the present invention, for positive charging, high sensitivity, spectral sensitivity in a long wavelength region, no image defects, durability against ozone, nitrogen oxides or ultraviolet rays, and excellent image stability. An electrophotographic photoreceptor can be provided.

[Brief description of the drawings]

FIG. 1 is a layer configuration diagram of an example of a photoreceptor having an embodiment of the present invention.

FIG. 2 is an X-ray diffraction spectrum of the crystalline form of perylene pigment of the present invention.

FIG. 3 is an X-ray diffraction spectrum of a crystal form of perylene pigment outside the present invention.

FIG. 4 is a view for explaining the definitions of peak intensity and half width in the present invention.

[Explanation of symbols]

 Reference Signs List 1 support 2 photoconductive layer (PCL) 3 protective layer 4 intermediate layer 5 charge transport layer (CTL) 6 charge generation layer (CGL)

Continuation of front page (56) References JP-A-5-281769 (JP, A) JP-A-5-249719 (JP, A) JP-A-5-6015 (JP, A) JP-A-5-80564 (JP) JP-A-4-253061 (JP, A) JP-A-4-133063 (JP, A) JP-A-62-127843 (JP, A) JP-A-4-276761 (JP, A) JP-A-5-107789 (JP, A) JP-A-5-257297 (JP, A) JP-A-3-67263 (JP, A) JP-A-5-257299 (JP, A) JP-A-5-6016 (JP, A A) Japanese Patent Application Laid-Open No. Hei 3-171053 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5 / 06,5 / 05

Claims (10)

(57) [Claims] An electrophotographic photoreceptor for positive charging comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, wherein the charge generating substance is represented by the following general formula (I) or (II): And the Bragg angle 2θ of the X-ray diffraction spectrum for Cu-Kα ray is 6.3 ± 0.2 °, 12.4 ± 0.2 °, 2
A crystal having peaks at 5.3 ± 0.2 ° and 27.1 ± 0.2 °, having a maximum peak intensity at 12.4 ± 0.2 °, a half width of the peak is 0.65 or more, and a clear peak at 11.5 ± 0.2 ° Is a perylene pigment having a crystalline form without
Thus, the perylene pigment is subjected to sublimation purification, and then to an acid paste.
Positively chargeable electrophotographic photosensitive member, characterized in der Rukoto shall be processed. Embedded image (In the formula, Z represents a group of atoms necessary to form a substituted or unsubstituted heterocyclic ring.) 2. The electrophotographic photosensitive member for positive charging according to claim 1, wherein the average particle diameter of the charge generating substance is 1.0 μm or less. 3. The photosensitive layer according to claim 1, wherein the photosensitive layer is a single layer and contains a charge generating substance and a charge transporting substance.
Or the electrophotographic photosensitive member for positive charging according to 2. 4. The positive charging device according to claim 1, wherein the photosensitive layer is laminated on a substrate in the order of a charge transport layer containing at least a charge transport material and a charge generation layer containing a charge generation material. Electrophotographic photoreceptor. 5. The electrophotographic photosensitive member for positive charging according to claim 4, wherein the charge generation layer contains a charge transport material. 6. The electrophotographic photosensitive member for positive charging according to claim 1, wherein a protective layer is provided on the photosensitive layer. 7. A method for producing a positively charged electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, wherein the charge generating substance contained in the photosensitive layer is as follows: Represented by the formula (I) or (II), and Cu-K
Bragg angle 2θ of X-ray diffraction spectrum with respect to α-ray is 6.
3 ± 0.2 °, 12.4 ± 0.2 °, 25.3 ± 0.2 ° and 27.1 ± 0.2 °
A crystal having a peak at 12.4 ± 0.2 ° has a maximum peak intensity, and the half width of the peak is 0.65 or more,
And it perylene pigments der having a crystal form which does not have a clear peak at 11.5 ± 0.2 °, the perylene pigment sublimation
After purification state, and are intended to be acid paste treatment, coating liquid circular amount control type positively chargeable electrophotographic photosensitive, which comprises forming at least a photosensitive layer by applying a coating machine comprising the charge generating material How to make the body. Embedded image (In the formula, Z represents a group of atoms necessary to form a substituted or unsubstituted heterocyclic ring.) 8. A method for producing a positively charged electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive substrate, wherein the charge generating substance contained in the photosensitive layer is as follows: Represented by the formula (I) or (II), and Cu-K
Bragg angle 2θ of X-ray diffraction spectrum with respect to α-ray is 6.
3 ± 0.2 °, 12.4 ± 0.2 °, 25.3 ± 0.2 ° and 27.1 ± 0.2 °
A crystal having a peak at 12.4 ± 0.2 ° has a maximum peak intensity, and the half width of the peak is 0.65 or more,
And it perylene pigments der having a crystal form which does not have a clear peak at 11.5 ± 0.2 °, the perylene pigment sublimation
After purification state, and are intended to be acid paste treatment, the coating solution process for producing a positive charging electrophotographic photosensitive member and forming at least a photosensitive layer is applied by a spray coating containing the charge generating substance . Embedded image (In the formula, Z represents a group of atoms necessary to form a substituted or unsubstituted heterocyclic ring.) 9. The photosensitive layer is a single layer and contains a charge generating substance and a charge transporting substance.
Or the method for producing an electrophotographic photosensitive member for positive charging according to item 8. 10. The electrophotography for positive charging according to claim 7, wherein a charge transport layer containing at least a charge transport substance and a charge generation layer containing a charge generation substance are laminated on the photosensitive layer in this order. Manufacturing method of photoreceptor.