JPH0531137B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to an electrophotographic photoreceptor using a specific crystal type of oxytitanium phthalocyanine in a charge generation layer. <Prior Art> Phthalocyanines and metal phthalocyanines have conventionally shown good photoconductivity and have been used, for example, in electrophotographic photoreceptors. In addition, in recent years, laser beam printers that use laser light as a light source instead of conventional white light and have the advantages of high speed, high image quality, and non-impact properties have become widespread, and the development of photoreceptors that can withstand these demands. is popular. In particular, various attempts have been made to use semiconductor lasers as light sources, which have seen remarkable progress in recent years among laser light sources. A photoreceptor having these characteristics is strongly desired. Organic photoconductive materials that meet this requirement include squaric acid methine dyes, cyanine dyes, pyrylium dyes, thiapyrylium dyes,
Polyazo dyes, phthalocyanine dyes, etc. are known. Among these, methine squaritcate dyes,
Cyanine dyes, pyrylium dyes, and thiapyrylium dyes are relatively easy to increase spectral sensitivity to longer wavelengths, but they lack practical stability when used repeatedly, and polyazo dyes have long absorption wavelengths. It is difficult to convert wavelengths, and in terms of manufacturing, there are drawbacks such as long processes and difficulty in separating impurities. On the other hand, phthalocyanine dyes have an absorption peak in the long wavelength range of 600 nm or more, and their spectral sensitivity changes depending on the central metal and crystal type, and some have been announced that show high sensitivity in the wavelength range of semiconductor lasers. Research and development is being carried out vigorously. Phthalocyanines not only have different absorption spectra and photoconductivity depending on the type of central metal, but also
There are differences in these physical properties depending on the crystal type, and there have been several reports of cases in which a specific crystal type has been selected for use in electrophotographic photoreceptors, even for phthalocyanines with the same central metal. It has been reported that the X-type crystal type of metal-free phthalocyanine has high photoconductivity and is sensitive to wavelengths of 800 nm or more, and among the many crystal types of copper phthalocyanine, the ε-type is the longest. It is reported that it has sensitivity up to the wavelength range. However, X-type metal-free phthalocyanine is a metastable crystalline type, and its production is difficult;
The disadvantage is that it is difficult to obtain products of stable quality. On the other hand, the spectral height of ε-type copper phthalocyanine extends to longer wavelengths than that of α- and β-type copper phthalocyanines, but the sensitivity at 800 nm is sharply lower than that at 780 nm, and the current oscillation wavelength has a fluctuation. Its performance makes it difficult to use for semiconductor lasers. For this reason, many metal phthalocyanines have been investigated, including oxyvanadyl phthalocyanine, chloroaluminum phthalocyanine, chloroindium phthalocyanine, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and magnesium phthalocyanine, which are highly sensitive to near-infrared light such as semiconductor lasers. It has been reported as a sensitive phthalocyanine. However, in order to use these phthalocyanines as charge generating materials for electrophotographic photoreceptors for copying machines and printers, they must satisfy not only sensitivity but also many other performance requirements. In terms of initial electrical properties, it is necessary not only to have high sensitivity to semiconductor laser light, but also to have good charging properties, low dark decay, and low residual potential; It is required that it does not change significantly due to repeated use. Particularly recently, increasing the lifespan of photoreceptors has become important.
There is a strong demand for electrical properties that do not easily change due to repeated use. In this respect, there is still nothing that is fully satisfactory.
Electrical properties vary greatly depending on the type of coordinating metal of the phthalocyanine, but even for the same metal phthalocyanine, there are large differences in properties depending on the crystal form. For example, for copper phthalocyanine, α, β, γ, ε
Due to differences in crystal form such as type, chargeability, dark decay,
It is known that there are large differences in sensitivity, etc.
(Manabu Sawada; Dyes and Drugs, Vol. 24, No. 6, p. 122
(1979)) Also, because the absorption spectrum differs depending on the crystal form, the spectral altitude also changes, and in copper phthalocyanine, the ε-type absorption is on the longest wavelength side, and the spectral altitude also extends to the longest wavelength side. (Isao Kumano:
(Journal of the Electrophotographic Society Vol. 22, No. 2, p. 111 (1984)) Differences in electrical properties due to crystal forms are well known for metal-free phthalocyanines and many other metal phthalocyanines, and Many efforts have been made to find out how to create a good crystalline form. For example, a vapor-deposited film of metal phthalocyanine is often used as a charge-generating layer, but by immersing this vapor-deposited film in an organic solvent such as dichloromethane or tetrahydrofuran or exposing it to solvent vapor, a crystal transition is caused and the electrical properties are changed. Examples of improvement have been reported for phthalocyanine of aluminum, indium, and titanium (JP-A-58-158649, JP-A-59-44054, JP-A-59-49544, JP-A-59)
-155851 and JP-A-59-166959. ). Among them, JP-A-59-49544 and JP-A-59-
Publication No. 166959 reports the use of a specific crystal type of oxytitanium phthalocyanine in an electrophotographic photoreceptor. In JP-A-59-49544, the crystal forms of oxytitanium phthalocyanine are Bragg angle (2θ±0.2°) = 9.2°, 13.1°, 20.7°, 26.2°, 27.
It is written that those giving a strong diffraction peak at 1° are suitable, and an X-ray diffraction spectrum is shown.
There are several other peaks in this spectrum, and the presence of a peak with the second highest intensity between 7° and 8° is shown. Furthermore, in Japanese Patent Application Laid-Open No. 166959/1983, a vapor-deposited film of oxytitanium phthalocyanine is left in saturated vapor of tetrahydrofuran for 1 to 24 hours to change the crystal form and form a charge generation layer. The X-ray diffraction spectrum has a small number of peaks,
and wide, Bragg angle (2θ) = 7.5°, 12.6°,
It is characterized by strong diffraction peaks at 13.0°, 25.4°, 26.2°, and 28.6°. These known oxytitanium phthalocyanines form a charge generation layer mainly by vapor deposition, and after vapor deposition, they are exposed to solvent vapor to cause crystal transition, and it is finally possible to obtain a charge generation layer that is suitable for practical use. However, compared to the coating method, the vapor deposition method is not preferable because it requires a large capital investment and is inferior in mass productivity, resulting in high costs. According to the studies conducted by the present inventors, when using oxytitanium phthalocyanine which has a strong diffraction peak at a black angle of 8 degrees or less, the performance of a photoreceptor in which a charge generation layer is formed by coating this dispersion is particularly poor. It turns out that the results are not necessarily satisfactory. This can be seen, for example, from the example of Japanese Patent Application Laid-Open No. 59-49544. That is, a photoreceptor formed by coating has a lower chargeability and a higher residual potential than a photoreceptor formed by vapor deposition, and its sensitivity is about 40% lower than that of a photoreceptor formed by vapor deposition. In this way, the performance of photoreceptors using oxytitanium phthalocyanine changes depending on the conditions.
This is because oxytitanium phthalocyanine has several crystal forms, and the electrical properties differ depending on the crystal form. Therefore, it is particularly necessary to investigate a manufacturing method for a crystalline form with good electrical properties, but conventional studies have mainly focused on vapor deposition methods, which are less suitable for mass production. No consideration has been made. The present inventors kept the above points in mind and conducted extensive studies to determine that oxytitanium phthalocyanine obtained by first suspending dichlorotitanium phthalocyanine in hot water and treating it with N-methylpyrrolidone is suitable for the coating method. (Special application 1982-
230982). Oxytitanium phthalocyanine obtained by such a purification method generally exhibits better electrical properties than those obtained by conventional methods, but upon further investigation by the present inventors, it was found that at least several types of crystal forms may be obtained depending on the purification conditions. was formed, and it was confirmed that there were differences in electrical properties between these crystal types. According to the studies of the present inventors, in particular, when suspending in hot water, it is necessary to thoroughly wash the liquid until the pH of the suspension becomes around 5 to 7 (Japanese Patent Application No. 60-12194), and furthermore, N-methyl Crystalline oxytitanium phthalocyanine, which exhibits a specific X-ray diffraction pattern obtained by sufficiently performing pyrrolidone treatment until the peak intensity at a Bragg angle of 4 to 8 degrees falls below a certain level, is particularly sensitive to sensitivity, chargeability, and darkness. They found that the material has good attenuation, residual potential, etc., and has well-balanced electrical characteristics, leading to the completion of the present invention. <Objective of the invention> The object of the present invention is to use a metal phthalocyanine that is highly sensitive to near-infrared light for semiconductor lasers, has excellent electrical properties, and has a specific crystal form that is easy to manufacture. The object of the present invention is to provide an electrophotographic photoreceptor using oxytitanium phthalocyanine that is highly sensitive to long wavelength light and has good other electrical properties. <Structure of the Invention> That is, the gist of the present invention is to provide an electrophotographic photoreceptor having at least a charge generation layer in which oxytitanium phthalocyanine is dispersed in a binder polymer and a photosensitive layer in which a charge transfer layer is laminated. In the line diffraction spectrum, the Bragg angle (2θ±0.2°) is 9.3°,
10.6°, 13.2°, 15.1°, 15.7°, 16.1°, 20.8°, 23
.3°,
It shows strong diffraction peaks at 26.3° and 27.1°, of which the diffraction peak at Bragg angle of 26.3° is the strongest.
And the intensity of the diffraction peak at a Bragg angle of 4 to 8° is 5% of the intensity of the diffraction peak at a Bragg angle of 26.3°.
An electrophotographic photoreceptor characterized by having the following strength. To explain the present invention in detail, the oxytitanium phthalocyanine of the present invention is
In its X-ray diffraction spectrum, Bragg angles (2θ±0.2°) = 9.3°, 10.6°, 13.2°, 15.1°, 15.
7°,
It shows strong diffraction peaks at 16.1°, 20.8°, 23.3°, 26.3°, and 27.1°, of which the peak intensity at 26.3° is the strongest.
Moreover, it is a crystalline oxytitanium phthalocyanine in which the diffraction peaks at 7.0° and 7.6° have an intensity of 5% or less compared to the peak intensity at 26.3°. As the oxytitanium phthalocyanine, for example, the following general formula [1] (In the formula, X represents a halogen atom, and n represents a number from 0 to 1.) In the general formula [1], X is a chlorine atom and n
is preferably from 0 to 0.5. The oxytitanium phthalocyanine of the present invention is
For example, from 1,2-dicyanobenzene (o-phthalodinitrile) and a titanium compound, for example, the following (1) or
It can be easily synthesized according to the reaction formula shown in (2). That is, 1,2-dicyanobenzene (phthalodinitrile) and a titanium halide are heated and reacted in an inert solvent. As the titanium compound, titanium tetrachloride, titanium trichloride, titanium tetrabromide, etc. can be used, but titanium tetrachloride is preferable in terms of cost. Inert agents include trichlorobenzene, α-chloronaphthalene, β-chloronaphthalene, α-methylnaphthalene, methoxynaphthalene, diphenyl ether, diphenylmethane, diphenylethane, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether. A high boiling point organic solvent that is inert to the reaction is preferred. The reaction temperature is usually 150 to 300°C, particularly preferably 180 to 250°C. After the reaction, the dichlorotitanium phthalocyanine produced is separated and washed with the solvent used in the reaction to remove impurities produced during the reaction and unreacted raw materials. Next, the solvent used in the reaction is removed by washing with an inert solvent such as alcohols such as methanol, ethanol, and isopropyl alcohol, and ethers such as tetrahydrofuran and 1,4-dioxane. The obtained dichlorotitanium phthalocyanine is then treated with hot water to become oxytitanium phthalocyanine. It is desirable to repeat the hot water treatment until the pH of the washing liquid reaches approximately 5-7. In the X-ray diffraction spectrum of oxytitanium phthalocyanine obtained at this stage, the peaks become broader, indicating that the crystal arrangement is disturbed by the hydrolysis reaction in which chlorine atoms are replaced with oxygen atoms. This oxytitanium phthalocyanine is combined with quinoline, α-chloronaphthalene, N
-Methylpyrrolidone, etc., preferably N-methylpyrrolidone. At that time, the reactants are washed with a reaction solvent heated to around 100°C, then washed with a reaction solvent around room temperature, and then washed with an inert solvent such as methanol at around room temperature, and then washed with a reaction solvent heated to around 100°C. Washing with an active solvent is preferred because it yields oxytitanium phthalocyanine with low electrical properties, particularly low residual potential. This organic solvent treatment is usually carried out at 100 to 180°C, preferably 130 to 170°C, and is carried out using an equivalent to 100 times, preferably 520 times the weight of the solvent relative to the oxytitanium phthalocyanine. If the X-ray diffraction peak of oxytitanium phthalocyanine treated with an organic solvent still has a diffraction peak of a certain degree of intensity at a Bragg angle of 8° or less, the organic solvent is used to repeatedly and sufficiently treat the oxytitanium phthalocyanine until the intensity of the diffraction peak specified in the present invention is reached. do. In this way, the crystalline oxytitanium phthalocyanine of the present invention can be obtained. To explain the photoreceptor of the present invention in more detail, the photoreceptor of the present invention is a laminated type photoreceptor in which a charge generation layer and a charge transfer layer are laminated, and at least
It consists of a conductive support, a charge generation layer, and a charge transfer layer. The charge generation layer and the charge transfer layer usually have a structure in which the charge transfer layer is laminated on the charge generation layer, but the structure may be reversed. In addition to these, intermediate layers such as adhesive layers and blocking layers, and layers for improving electrical properties and mechanical properties such as protective layers may be provided. As the conductive support, any of those employed in well-known electrophotographic photoreceptors can be used. Specifically, metal drums and sheets made of aluminum, stainless steel, copper, etc., or laminates and vapor deposits of these metal foils can be used. Furthermore, plastic films, plastic drums, etc., which are coated with conductive substances such as metal powder, carbon black, copper iodide, and polymer electrolytes together with suitable binders, are also available.
Examples include paper and paper tubes. Also included are plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are rendered conductive. Also included are plastic films and belts treated with conductive metal oxides such as tin oxide and indium oxide. The charge generation layer formed on these conductive supports comprises the oxytitanium phthalocyanine particles of the present invention, a binder polymer and, if necessary, an organic photoconductive compound,
It is obtained by coating and drying a coating liquid obtained by dissolving or dispersing a dye, an electron-withdrawing compound, etc. in a solvent. As binders, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, vinyl alcohol, ethyl vinyl ether, polyvinyl acetal, polycarbonate,
Examples include polyester, polyamide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, and epoxy resin. The ratio of oxytitanium phthalocyanine and binder polymer is not particularly limited, but is generally 5 to 500 parts by weight, preferably 20 to 300 parts by weight, based on 100 parts by weight of oxytitanium phthalocyanine.
Parts by weight of binder polymer are used. The thickness of the charge generation layer is 0.05 to 5 μm, preferably
The thickness should be 0.1 to 2 μm. Charge carriers are injected from the charge generation layer.
The charge transport layer contains a carrier transport medium with high carrier injection and transport efficiency. As the carrier transfer medium, high molecular compounds having a heterocyclic compound or condensed polycyclic aromatic compound in the side chain such as poly-N-vinylcarbazole and polystyrylanthracene are used, and low molecular compounds such as pyrazoline and imidazole are used. , oxazole,
Heterocyclic compounds such as oxadiazole, triazole, and carbazole, triarylalkane derivatives such as triphenylmethane, triarylamine derivatives such as triphenylamine, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, Examples include hydrazone compounds, and particularly compounds with high electron donating properties substituted with electron donating groups such as substituted amino groups and alkoxy groups, or aromatic ring groups having these substituents. Furthermore, a binder polymer may be used in the charge transfer layer if necessary. The binder polymer is preferably a polymer that has good compatibility with the carrier transfer medium and does not cause crystallization or phase separation of the carrier transfer medium after coating film formation; examples thereof include styrene, vinyl acetate, and chloride. Polymers and copolymers of vinyl compounds such as vinyl, acrylic esters, methacrylic esters, butadiene, polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon Examples include resins and epoxy resins. When the carrier transfer medium is a polymer compound, it is not necessary to use a binder polymer, but it may be mixed to improve flexibility. In the case of low-molecular compounds, binder polymers are used for film-forming properties, and the amount used is usually 100 parts by weight of the carrier transfer medium.
It ranges from 50 to 3000 parts by weight, preferably from 70 to 1000 parts by weight. In addition to the above, various additives can be used in the charge transfer layer to improve the mechanical strength and durability of the coating film. Such additives include well-known plasticizers,
Various stabilizers, fluidity imparting agents, crosslinking agents, etc. may be mentioned. [Effects of the Invention] The electrophotographic photoreceptor of the present invention obtained in this manner and having a charge generation layer in which crystalline oxytitanium phthalocyanine is dispersed in a binder polymer has high sensitivity, low residual potential, and high chargeability. Moreover, since the variation due to repetition is small and the charging stability, which affects image density, is particularly good, it can be used as a highly durable photoreceptor. Also 750
Since it has high sensitivity in the region of ~800 nm, it is particularly suitable as a photoreceptor for semiconductor laser printers. [Example] The present invention will be described in more detail below with reference to Examples, Comparative Examples, and Application Examples. Production Example 1 97.5 g of phthalodinitrile is added to 750 ml of α-chloronaphthalene, and then 22 ml of titanium tetrachloride is added dropwise under a nitrogen atmosphere. After the dropwise addition, the temperature was raised, and the mixture was allowed to react at 200 to 220°C for 3 hours while stirring, and then allowed to cool.
α− heated at 100 to 130℃ and then heated to 100℃
Washed with 200 ml of chloronaphthalene. The obtained crude cake was suspended washed with 300 ml of α-chloronaphthalene, then 300 ml of methanol at room temperature, and then hot washed several times with 800 ml of methanol for 1 hour, and the obtained cake was suspended in 700 ml of water. The mixture was made cloudy and hot suspension washing was performed for 2 hours. The pH was below 1. Hot water washing with liquid
This was repeated until the pH reached 6-7. After this, in 700 ml of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Industries, Ltd.),
Hot suspension washing was carried out at 140-145°C for 2 hours, and this operation was repeated 4 times. Next, hot suspension washing was carried out twice with 800 ml of methanol. The yield was 76.6g. The elemental analysis values of the obtained oxytitanium phthalocyanine were as follows. Elemental analysis value (C ₃₂ H ₁₆ N ₈ TiO) C H N Calculated value (%) 66.68 2.80 19.44 Actual value (%) 66.35 3.00 19.42 Cl Ash content (as TiO ₂ ) Calculated value (%) 0 13.86 Actual value (%) 0.49 13.80 The X-ray diffraction spectrum of this oxytitanium phthalocyanine is shown in Figure-1. As is clear from Figure 1, the Bragg angle (2θ±
0.2°), there is no peak from 4° to 8°, 9.3°, 10.6°
,
13.2°, 15.1°, 15.7°, 16.1°, 20.8°, 23.3°, 26
.3°,
There is a strong diffraction peak at 27.1°, of which the peak at 26.3° is the strongest. This crystal type is designated as type I. In order to show that this crystal form was generated during the manufacturing process, an X-ray diffraction spectrum of a sample at an intermediate stage was measured. Figure 2 shows the spectrum of the sample (mold) after hot water suspension washing. In Figure 2, there is a sharp peak at 27.3°, but the other peaks are broad, indicating that the crystallinity has been disturbed by the hydrolysis reaction. When this crystal state is heated and washed with N-methylpyrrolidone, the molecules are rearranged, and as shown in Figure 1, the peak at 26.3°, which was not in Figure 2, becomes the strongest peak. −2 to 7° to 8°
The broad peak in the crystalline form disappeared and changed to form I, which is the crystal form of the present invention. Next, in order to measure the absorption spectra of these oxytitanium phthalocyanines, a dispersion of oxytitanium phthalocyanine was prepared by the method described in Example 1, which will be described later, and applied to a polyester film with a thickness of 100 μm and dried. A dispersed layer of phthalocyanine pigment was formed and the absorption spectrum was measured. The absorption spectrum of type I crystal is shown in Figure 3.
Figure 4 shows the absorption spectrum of the crystal type. Production Example 2 In Production Example 1, the reaction temperature was set to 225°C,
Oxytitanium phthalocyanine was produced in the same manner as Production Example 1 except that the reaction was carried out for 3 hours. When the X-ray diffraction spectrum of this sample was measured, as shown in Figure 5, almost the same spectrum as the sample of Production Example 1 (Figure 1) was obtained. However, weak peaks were observed at 2θ = 6.7° and 7.6°.
The ratios of these peak intensities to the strongest peak at 26.3° were 1.4% and 2.6%, respectively. Production Example 3 Hydrothermal treatment was carried out in the same manner as in Production Example 1 to obtain crystalline oxytitanium phthalocyanine. 5 g of this oxytitanium phthalocyanine was hot washed in 100 ml of quinoline at a temperature of 140 to 145° C. for 2 hours. This operation was performed four times. Further, hot washing was carried out twice in methanol at 60 to 65°C for 1 hour. X of the obtained oxytitanium phthalocyanine
The line diffraction spectrum is shown in Figure 6. This crystal form shows a spectrum similar to the type. Bratzg angle
Weak peaks are seen at 6.9° and 7.6°. The intensity ratio of these peaks to the 26.3° peak is 2.2%, respectively.
It was 2.0%. Production example 4 (comparative example) 46g of phthalodinitrile was converted into α-chloronaphthalene.
After pouring into 250ml and heating and dissolving, 10ml of titanium tetrachloride was added dropwise and stirred at 150℃ for 30 minutes.
Then, the temperature was gradually raised and the mixture was heated and stirred at 220°C for 2 hours. Thereafter, the reaction system was allowed to cool while stirring, and when the temperature of the reaction system dropped to 100°C, it was heated, and then a hot methanol suspension and a hot water boiling suspension (the pH of the reaction system was 1 or less) were added to each. After one time, thermal suspension was carried out at 120°C for 1 hour with N-methylpyrrolidone, and after heating, the suspension was heated and filtered with methanol, and then dried under reduced pressure to obtain 29.5 g of oxytitanium phthalocyanine as a blue powder. . The elemental analysis values of this compound were as follows. Elemental analysis value (C ₃₂ H ₁₆ N ₈ TiO) C(%) H(%) N(%) Cl(%) Calculated value 66.68 2.80 19.44 − Actual value 66.49 3.02 19.35 0.85 In addition, the X-ray diffraction spectrum is shown in the figure − 7. Diffraction peaks are seen at Bragg angles of 7.0° and 7.6°. The intensity ratios of these peaks to 26.3° were 10.9% and 23.6%, respectively. Production Example 5 (Comparative Example) Oxytitanium phthalocyanine was prepared in exactly the same manner as Production Example 1, except that the solvent shown in Table 1 was used instead of N-methylpyrrolidone as the solvent for hot washing after hot water washing. was produced, and the powder X-ray diffraction spectrum of the oxytitanium phthalocyanine was measured. In the obtained X-ray diffraction spectrum,
Table 1 shows the results of reading the Bragg angles (2θ±0.2) of the four diffraction peaks in order from the one with the highest intensity.

[Table] Example 1 0.4 g of oxytitanium phthalocyanine produced in Production Example 1 and 0.2 g of polyvinyl butyral were mixed into 4-
Disperse the dispersion with 30 g of methoxy-4-methyl-2-pentanone using a sand grinder, and apply the dispersion liquid to the aluminum vapor deposited layer on the polyester film using a film applicator to reduce the dry film thickness.
It was coated at a concentration of 0.3 g/m ² and dried to form a charge generation layer. On this charge generation layer, 4-N,N-diethylaminobenzaldehyde diphenylhydrazone 90
and polycarbonate resin (manufactured by Mitsubishi Chemical Industries, Ltd.)
Novarex 7025A) 17.5 μm thick film consisting of 100 parts
Charge transfer layers were laminated to obtain an electrophotographic photoreceptor having a laminated type photosensitive layer. The sensitivity of this photoreceptor is the half-decreased exposure amount (E1/2)
Electrostatic copying paper testing device (model manufactured by Kawaguchi Electric Seisakusho)
SP-428). That is, the photoreceptor is negatively charged by corona discharge with an applied voltage set so that the corona current is 22 μA in a dark place, and then
Exposure to white light with an illuminance of 5 lux, and the surface potential is -
Exposure required to halve from 450V to -225V (E
1/2) was found to be 0.57 lux・sec. At this time, the charged voltage (initial surface potential) of the photoreceptor is -
The voltage was 746V, the dark decay was 23V/sec, and the surface potential (residual potential) after 10 seconds of exposure was -5V. Next, after charging this photoreceptor, white light of 400 lux was applied for 0.4 seconds of dark decay.
Repeatability characteristics were evaluated using a 2.0 second exposure cycle. The charging voltage after 2000 repetitions is the initial
95%, residual potential was -9V. Example 2 In the charge transfer layer of Example 1, 4-N, N-
Example 1 except that 70 parts of N-methyl-3-carbazolecarbadehyde diphenylhydrazone and 2 parts of p-nitrobenzoyloxybenzalmalonitrile were used instead of diethylbenzaldehyde diphenylhydrazone, and the film thickness was 13 μm. A photoreceptor having a laminated photosensitive layer was obtained in the same manner as above. The initial sensitivity of this photoreceptor is 0.65lux・sec, and the charged voltage is −
The voltage was 618V, the dark decay was 10V/sec, and the residual potential was -18V. Furthermore, the charged voltage under the condition of a corona current of 50 μA was -963V. After 2000 repetitions, the charged voltage was 100.5% of the initial value, with almost no fluctuation, and was extremely stable. The residual potential was -38V. When we measured the amount of exposure required for the surface potential to be halved from -400V to -200V, the initial value was 0.60lux・sec, 2000
There was almost no change at 0.61lux・sec after the cycle. The spectral sensitivity was measured by exposure to light separated by a Shimadzu Boschulom diffraction grating type strong monochromator.
Figure 8 shows the measured spectral sensitivity curve. In FIG. 8, the vertical axis represents the reciprocal of the half-decrease exposure amount as the sensitivity, and the horizontal axis represents the wavelength. As is clear from Figure 8, 750 to 800n
In the semiconductor laser light region of m, the sensitivity is almost the same, indicating that the sensitivity is stable even when the oscillation wavelength fluctuates due to the swing of the semiconductor laser and the temperature. The half-decrease exposure amount for light of 800 nm is 0.39 μJ/cm ² , which is extremely high sensitivity. As described above, the crystal type oxytitanium phthalocyanine of the present invention has good charging properties, low dark decay and residual potential, and high sensitivity in the semiconductor laser light region of 750 to 800 nm. Moreover, the charging voltage hardly changes even after repeated use.
It turned out to be extremely stable. Example 3 Example 2 except that the oxytitanium phthalocyanine produced in Production Example 2 was used instead of the oxytitanium phthalocyanine used in Example 2.
A photoreceptor was produced in the same manner as described above. The initial sensitivity of this photoreceptor is 0.69lux・sec, the charged voltage is -605V, the dark decay is 12V/sec, and the residual potential is -
It was 21V. Furthermore, the charged voltage was 930 V under the condition of a corona current of 50 μA. The charged voltage after 2000 repetitions was almost constant at 100.3% of the initial value, and the residual potential was -40V. As described above, although very weak diffraction peaks are observed at 6.7° and 7.6° in the X-ray diffraction spectrum of the oxytitanium phthalocyanine of this example, there is no major effect on the electrical properties, and the It exhibited very good performance, with only fluctuations within the range of runout. Example 4 A photoreceptor was produced in the same manner as in Example 2, except that the oxytitanium phthalocyanine produced in Production Example 3 was used instead of the oxytitanium phthalocyanine used in Example 2. The initial sensitivity of this photoreceptor is 0.77lux・sec, the charging voltage is -595V, the dark decay is 13V/sec, and the residual potential is -
It was 27V. The charged voltage after 2000 repetitions remained 100.0% of the initial value with almost no fluctuation. Comparative Example 1 A photoreceptor was prepared using crystalline oxytitanium phthalocyanine of the type obtained in Production Example 1 instead of the oxytitanium phthalocyanine used in Example 2, and its electrical properties were measured. These results are shown in Table 2. As is clear from the table, compared to the crystal type of the present invention, the type has a lower charging voltage and also has a higher dark decay and residual potential. Furthermore, even if the applied voltage (corona current) is increased, the degree of increase in the charged voltage is small, indicating that the saturation charged voltage is low. The stability of charging voltage greatly affects the durability of the photoreceptor. The level that can be put to practical use is considered to be 90% or more in this evaluation, and the sample of the comparative example is insufficient for practical use. As described above, the electrophotographic photoreceptor of the present invention has good charging properties, high sensitivity, and low dark decay and residual potential by using a specific crystal type oxytitanium phthalocyanine dispersion layer as a charge generation layer. ,
It is a durable photoreceptor with particularly excellent repeat stability, and is particularly suitable as a photoreceptor for semiconductor lasers.

[Table] *1 Corona current value
*2 Comparative example of the ratio of charging voltage after 2000 cycles to the initial charging voltage 2 Same as Example 1 except that oxytitanium phthalocyanine manufactured in Production Example 4 was used instead of oxytitanium phthalocyanine produced in Production Example 1. An electrophotographic photoreceptor was obtained. E1/2 was determined using this photoreceptor.
It was 1.0lux・sec. Further, the charging voltage at this time was -520V, the dark decay was 21V/sec, and the surface potential after 10 seconds of exposure was -27V. Also, corona current 50μA
The charged voltage was -770V. Next, after charging this photoreceptor, the dark decay time was 0.4 seconds.
Characteristics were repeatedly evaluated using a cycle of exposure to 400 lux white light for 2.0 seconds. After 2000 repetitions, the charged voltage was 85% of the initial value and the residual potential was -54V.

[Brief explanation of the drawing]

Figures 1 and 3 show the X-ray diffraction spectrum and absorption spectrum of the crystalline oxytitanium phthalocyanine of the present invention obtained in Production Example 1. FIG. 2 and FIG. 4 show the X-ray diffraction spectrum and absorption spectrum of the sample after hot water suspension washing in Production Example 1. Figure-5 and Figure-6 are
1 shows X-ray diffraction spectra of crystalline oxytitanium phthalocyanine of the present invention obtained in Production Example 2 and Production Example 3. FIG. 7 shows the X-ray diffraction spectrum of oxytitanium phthalocyanine obtained in Production Example 4. FIG. 8 shows the spectral sensitivity curve of the photoreceptor obtained in Example 2.

Claims (1)

[Claims] 1 In an electrophotographic photoreceptor having a photosensitive layer including a charge generation layer in which at least oxytitanium phthalocyanine is dispersed in a binder polymer and a charge transport layer, oxytitanium phthalocyanine has a black angle (2θ±) in its X-ray diffraction spectrum. 0.2°) 9.3°, 10.6°, 13.2°, 15.1°
,
It shows strong diffraction peaks at 15.7°, 16.1°, 20.8°, 23.3°, 26.3°, 27.1°, and among these, the diffraction peak at a black angle of 26.3° has the strongest intensity, and at a black angle of 4 to 8°.
An electrophotographic photoreceptor characterized in that the intensity of the diffraction peak at a Black angle of 26.3 is 5% or less of the intensity of the diffraction peak at a Black angle of 26.3.