JPH04221962A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body good in electric chargeability, high in sensitivity, and superior in durability. CONSTITUTION:Titanyl phthalocyanine to be added into a photosensitive layer as a carrier generating material has a peak in the Bragg angle 2theta of 27.2 deg. in the X-ray diffraction microscopy using CuKalpha intrinsic X-ray as shown in the graph where X is angle (2theta) and Y is X-ray intensity and it has a heat- emitting peak at 275-350 deg.C in the differential thermal analysis.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electrophotographic photoreceptor.
In particular, titanyl phthalocyanine having a specific crystal type is used as a photoconductive material, and it is effective for printers, copiers, etc., and is also suitable for image formation using semiconductor laser light, LED light, etc. as an exposure means. The present invention relates to an electrophotographic photoreceptor.

0002

BACKGROUND OF THE INVENTION In recent years, research on photoconductive materials has been actively conducted, and they are being applied as photoelectric conversion elements in electrophotographic photoreceptors, solar cells, image sensors, and the like. Conventionally, inorganic materials have been mainly used as these photoconductive materials. For example, in electrophotographic photoreceptors, a photosensitive layer mainly composed of inorganic photoconductive materials such as selenium, zinc oxide, and cadmium sulfide has been provided. Inorganic photoreceptors have been 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, printers, and the like. For example, selenium crystallizes due to heat, fingerprint stains, etc., so its properties as an electrophotographic photoreceptor tend to deteriorate. Further, electrophotographic photoreceptors using cadmium sulfide have poor moisture resistance and durability, and electrophotographic photoreceptors using zinc oxide also have problems in durability.

Furthermore, in recent years, environmental issues have become particularly important, but electrophotographic photoreceptors made of selenium, cadmium sulfide, and the like have the drawback of being subject to significant manufacturing and handling restrictions due to toxicity.

In order to improve the drawbacks of such inorganic photoconductive materials, various organic photoconductive materials have attracted attention, and in recent years, attempts have been made to use them in photosensitive layers of electrophotographic photoreceptors, etc. Research is being actively conducted. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing polyvinylcarbazole and trinitrofluorenone. However, this photoreceptor does not have sufficient sensitivity and durability. Therefore, a functionally separated electrophotographic photoreceptor has been developed in which the carrier generation function and the carrier transport function are assigned to different substances.

In such an electrophotographic photoreceptor, materials can be selected from a wide range, making it easy to obtain desired characteristics.
Therefore, it is expected that an excellent organic photoreceptor with high sensitivity and high durability can be obtained.

[0007] Various organic compounds have been proposed as carrier-generating substances and carrier-transporting substances for such functionally separated electrophotographic photoreceptors. It is responsible for the following functions. As carrier-generating substances, photoconductive substances such as polycyclic quinone compounds typified by dibromoanthron, pyrylium compounds and eutectic complexes of pyrylium compounds, squarium compounds, phthalocyanine compounds, and azo compounds have been put into practical use. Ta. In addition, since carrier-generating substances are generally applied by dispersing or dissolving them in an organic solvent, good dispersibility and high dispersion stability of the carrier-generating substances are required in order to obtain a good electrophotographic photoreceptor. required.

There is also a need for a carrier generating material with high carrier generation efficiency that provides higher sensitivity to electrophotographic photoreceptors. In this regard, in recent years, phthalocyanine compounds have attracted attention as excellent photoconductive materials, and active research is being conducted.

It is known that various physical properties of phthalocyanine compounds, such as spectra and photoconductivity, change depending on the type of central metal and the crystal type. For example, copper phthalocyanine has α, β, γ, and ε crystal forms, and it has been reported that there are large differences in electrophotographic properties depending on these crystal forms (Manabu Sawada, “Dye and Pharmaceuticals,” 24(6), 122 (1979)). In recent years, titanyl phthalocyanine has received particular attention, and four main crystal forms called A, B, C, and Y types have been reported for titanyl phthalocyanine as well. However, type A of JP-A-62-67094, JP-A-61-239
The type B titanyl phthalocyanine described in No. 248 and the type C titanyl phthalocyanine described in JP-A No. 62-256865 are still unsatisfactory in terms of chargeability, electrophotographic sensitivity, durability, etc. In addition, recently announced Y-type titanyl phthalocyanine (Oda et al., "Journal of Electrophotography Society", 29(3), 250, (19
90)) has high sensitivity, but in order to fully and stably exhibit its characteristics, in addition to controlling the crystal type, there are also issues related to chemical purity such as the type and content of impurities contained in the pigment. Issues such as crystal stability remain.

0010

OBJECTS OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor using titanyl phthalocyanine which overcomes the above-mentioned problems and has good charging properties, high sensitivity, and excellent durability.

[0011]

[Structure of the Invention] The purpose of the present invention is to obtain characteristic X-rays (
Bragg angle 2θ for wavelength 1.541A) is 27.2
titanyl phthalocyanine having a peak at ±0.2°;
Preferably, titanyl phthalocyanine having peaks at 9.5±0.2° and 27.2±0.2° has an exothermic peak at 275° C. or higher and 350° C. or lower in differential thermal analysis, and the titanyl phthalocyanine is contained in the photosensitive layer. This can be achieved by

It is well known that when a phthalocyanine of the general formula is used in an electrophotographic photoreceptor, its properties vary significantly depending on its crystal type. Therefore, as a phthalocyanine for electrophotographic photoreceptors, it has good charging properties, high sensitivity,
A stable crystal form with excellent durability is also required. In this respect, the Bragg angle 2θ used in the present invention is 27
．． Titanyl phthalocyanine having a peak at 2±0.2° has excellent chargeability and sensitivity. However, as a result of detailed study by the inventors, we found that the properties differ not only depending on the crystal type but also the temperature at which an exothermic peak corresponding to the crystal transition point observed in the region of 150 to 400°C appears in differential thermal analysis. Ta. This exothermic peak is not observed in thermally stable A, B, and C type crystals, but in the titanyl phthalocyanine of the present invention, which has a peak at Bragg angle 2θ of 27.2 ± 0.2°, differential thermal analysis It was found that titanyl phthalocyanine, which has an exothermic peak at 275° C. or higher and 350° C. or lower, exhibits excellent electrophotographic properties, particularly in terms of durability.

As a method for obtaining the titanyl phthalocyanine of the present invention, the crystal form can be converted into the desired crystal form of the present invention by a specific crystal conversion treatment. Next, there are various methods to obtain titanyl phthalocyanine that has an exothermic peak of 275°C or more and 350°C or less in differential thermal analysis, but the inventors believe that one of them is that the temperature of the exothermic peak can be determined by the type of impurity contained in titanyl phthalocyanine. We found that it is affected by the amount of water and its content. These factors can be removed by controlling the synthesis conditions, or by incorporating specific additives into the titanyl phthalocyanine. However, the method for obtaining titanyl phthalocyanine having an exothermic peak at 275° C. or higher and 350° C. or lower is not limited to this method.

The titanyl phthalocyanine used in the present invention is represented by the following general formula [I].

[0015]

[Chemical formula 1]

However, X1, X2, X3, and X4 represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or an aryloxy group, and k, l, m, and n represent integers of 0 to 4. The X-ray diffraction spectrum is measured under the following conditions, and the peak here refers to a distinct acute-angled protrusion that is different from noise.

X-ray tube Cu voltage
40.0 KV electric
flow 100
mA start angle 6.0
deg. Stop angle 3
5.0 deg. step angle
0.02 deg. Measurement time
0.50 sec. Differential thermal analysis was performed using a sample amount of 10 to 50 mg per measurement, and the heating rate was 30 (K/min). As the measurement sample, a crystalline titanyl phthalocyanine powder of the present invention immediately after synthesis was used. However, when titanyl phthalocyanine peeled off from a photosensitive drum prepared using this powder sample was similarly measured and compared with that immediately after synthesis, the same results were obtained. In addition, the exothermic peak observed at 150 to 400°C by differential thermal analysis is unique to the crystal form of titanyl phthalocyanine of the present invention among the various crystal forms of titanyl phthalocyanine that exist. It is possible to determine whether or not it is titanyl phthalocyanine. Furthermore, the exothermic peak in differential thermal analysis refers to a clear peak on a thermal differential curve, and the exothermic peak temperature indicates the temperature corresponding to the maximum point of the peak.

Various methods can be used to synthesize the titanyl phthalocyanine used in the present invention, but it can typically be synthesized according to the following reaction formula (1) or (2).

[0019]

[Case 2]

In the formula, R1 to R4 represent a leaving group.

The titanyl phthalocyanine obtained as described above can be converted into the crystal form used in the present invention by carrying out the following treatment.

For example, any crystalline form of titanyl phthalocyanine is dissolved in concentrated sulfuric acid, the sulfuric acid solution is poured into water, and the precipitated crystals are collected by filtration. This operation converts titanyl phthalocyanine into an amorphous state.

Next, the crystal form used in the present invention can be obtained by treating this amorphous titanyl phthalocyanine with a specific organic solvent in the presence of water. However, the crystal conversion method is not limited to this method.

The coating solution of the present invention and the electrophotographic photoreceptor obtained by coating the coating solution of the present invention may contain other photoconductive substances in addition to the above-mentioned phthalocyanine. Examples of other photoconductive substances include titanyl phthalocyanine such as A, B, C, amorphous, and AB mixed type titanyl phthalocyanine, which are different in crystal form from the titanyl phthalocyanine used in the present invention, as well as other phthalocyanine compounds, naphthalocyanine compounds, and other porphyrins. Examples include derivatives, azo compounds, polycyclic quinone compounds typified by dibromoanthrone, pyrylium compounds, eutectic complexes of pyrylium compounds, and squarium compounds.

Next, the electrophotographic photoreceptor obtained by containing the titanyl phthalocyanine of the present invention may also contain a carrier transporting substance. Various carrier transport substances can be used, but representative examples include compounds having a nitrogen-containing heterocyclic nucleus and its condensed ring nucleus, such as oxazole, oxadiazole, thiazole, thiadiazole, and imidazole; Arylalkane compounds, pyrazoline compounds, hydrazone compounds, triarylamine compounds, styryl compounds,
Examples include poly(bis)styryl compounds, styryltriphenylamine compounds, β-phenylstyryltriphenylamine compounds, butadiene compounds, hexatriene compounds, carbazole compounds, and fused polycyclic compounds. Specific examples of these carrier transport materials include those described in JP-A-61-107356, and the structures of particularly typical ones are shown below.

[0026]

[Chemical formula 3]

[0027]

[C4]

[0028]

[C5]

[0029]

[C6]

[0030]

[C7]

[0031]

[Chemical formula 8]

Various configurations of photoreceptors are known. Although the photoreceptor of the present invention can take any of these forms, it is preferably a laminated or dispersed functionally separated photoreceptor. In this case, the configuration is usually as shown in FIGS. 1 to 6. In the layer structure shown in FIG. 1, a carrier generation layer 2 is formed on a conductive support 1, and a carrier transport layer 3 is formed on this.
A photosensitive layer 4 is formed by laminating these layers, and FIG. 2 shows a photosensitive layer 4' in which the carrier generation layer 2 and carrier transport layer 3 are reversed. In FIG. 3, an intermediate layer 5 is provided between the photosensitive layer 4 and the conductive support 1 having the layer structure shown in FIG. The layer structure shown in FIG. 5 forms a photosensitive layer 4'' containing a carrier-generating substance 6 and a carrier-transporting substance 7, and FIG. An intermediate layer 5 is provided therein. In the configurations shown in FIGS. 1 to 6, a protective layer can be further provided on the outermost layer.

In forming the photosensitive layer, it is effective to apply a solution in which a carrier-generating substance or a carrier-transporting substance is dissolved alone or together with a binder and an additive. However, the solubility of the carrier-generating substance is generally low, so in such cases, a liquid in which the carrier-generating substance is dispersed into fine particles in an appropriate dispersion medium using a dispersion device such as an ultrasonic dispersion machine, a ball mill, a sand mill, or a homomixer is applied. This method is effective. In this case, the binder and additives are usually added to the dispersion.

A wide variety of solvents or dispersion media can be used for forming the photosensitive layer. For example, butylamine, ethylenediamine, N,N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, 4-methoxy-4-methyl-2-pentanone, tetrahydrofuran, dioxane, ethyl acetate, butyl acetate, acetic acid. -t-butyl, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, toluene, xylene, acetophenone, chloroform, dichloromethane, dichloroethane,
Examples include trichloroethane, methanol, ethanol, propanol, butanol, and the like.

[0035] When a binder is used to form the carrier generation layer or the carrier transport layer, any binder can be selected as the binder, but a hydrophobic polymer having film-forming ability is particularly desirable. Examples of such polymers include the following:
It is not limited to these. Polycarbonate Polycarbonate Z resin Acrylic resin
methacrylic resin polyvinyl chloride
polyvinylidene chloride polystyrene
Styrene-butadiene copolymer polyvinyl acetate polyvinyl formal polyvinyl butyral polyvinyl acetal polyvinyl carbazole
Styrene-alkyd resin silicone resin silicone-alkyd resin silicone-butyral resin polyester polyurethane polyamide epoxy resin phenolic resin vinylidene chloride-acrylonitrile copolymer vinyl chloride-vinyl acetate copolymer vinyl chloride-vinyl acetate-maleic anhydride copolymer for binder The proportion of the carrier-generating substance is preferably 10 to 600% by weight, more preferably 50 to 400% by weight. The ratio of carrier transport material to binder is preferably 10 to 500% by weight. The thickness of the carrier generation layer is 0.01 to 20 μm, more preferably 0.05 to 5 μm. The thickness of the carrier transport layer is 1 to 100 μm, more preferably 5 to 30 μm.

The photosensitive layer may contain an electron-accepting substance for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use. Examples of such electron-accepting substances include succinic anhydride, maleic anhydride, dibromo succinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromo phthalic anhydride, 3-nitro-phthalic anhydride, and 4-nitro-phthalic anhydride. Acid, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, p-nitrobenzonitrile, picryl chloride, Quinone chlorimide, chloranil, bromanil, dichlordicyano-
p-benzoquinone, anthraquinone, dinitroanthraquinone, 9-fluorenylidene malononitrile, polynitro-9-fluorenylidene malononitrile, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5
Examples include -dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds with high electron affinity. The addition ratio of the electron-accepting substance is preferably 0.01 to 200, more preferably 0.1 to 100, per 100 of the weight of the carrier generating substance.

[0037] The photosensitive layer also has storage stability, durability,
Anti-deterioration agents such as antioxidants and light stabilizers can be included for the purpose of improving environmental dependence resistance. Examples of compounds used for such purposes include chromanol derivatives such as tocopherol and their etherified or esterified compounds, polyarylalkane compounds,
Hydroquinone derivatives and their mono- and dietherified compounds, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phosphonic acid esters, phosphorous acid esters, phenylenediamine derivatives, phenolic compounds, hindered phenolic compounds, linear amine compounds,
Cyclic amine compounds, hindered amine compounds, etc. are effective. A specific example of a particularly effective compound is “IRGA
Hindered phenol compounds such as NOX 1010, IRGANOX 565 (manufactured by Ciba Geigy), Sumilizer BHT, Sumilizer MDP (manufactured by Sumitomo Chemical Co., Ltd.), "Sanol LS-2626", "Sanol LS-622LD" (manufactured by Sankyosha) and other hindered amine compounds.

As the binder used for the intermediate layer, protective layer, etc., those listed above for the carrier generation layer and carrier transport layer can be used, but in addition, nylon resin, ethylene-vinyl acetate copolymer, Ethylene resins such as ethylene-vinyl acetate-maleic anhydride copolymer and ethylene-vinyl acetate-methacrylic acid copolymer, polyvinyl alcohol, cellulose derivatives, and the like are effective. Further, a hardening type binder using thermosetting or chemical hardening such as melamine, epoxy, isocyanate, etc. can be used.

As the conductive support, a metal plate or a metal drum is used, or a thin layer of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum or palladium is coated, vapor-deposited, laminated, etc. Accordingly, it is possible to use one provided on a substrate such as paper or plastic film.

[0040]

[Example] Synthesis Example 1 29.2 g of 1,3-diiminoisoindoline, 200 ml of quinoline, and 50 ml of titanium tetraisopropoxide
．． 0 g were mixed and the reaction was carried out under reflux under a nitrogen stream for 5 hours. After cooling and returning to room temperature, the precipitated crystals were collected by filtration.
Washed with quinoline and further washed with methanol. Furthermore, the obtained crystals were washed several times with stirring in a 2% aqueous hydrochloric acid solution at room temperature, and the washing was repeated several times with deionized water. Thereafter, it was washed with methanol and dried to obtain 24.2 g of blue-purple crystals.

Next, 10 g of the obtained crystals were dissolved in 500 g of 96% sulfuric acid under ice cooling, and the sulfuric acid solution was poured into 10 liters of water, and the precipitated amorphous wet paste was collected by filtration.

Further, this wet paste and 100 g of o-dichlorobenzene were mixed and stirred at a temperature of 50° C. for 2 hours. The reaction solution was diluted with methanol and filtered, and the resulting crystals were washed several times with methanol to obtain blue crystals. As shown in FIG. 7, this crystal has a Bragg angle of 2θ of 9.
It was found that the titanyl phthalocyanine of the present invention has peaks at 5° and 27.2°, and an exothermic peak at 307°C by differential thermal analysis.

Synthesis Example 2 The titanyl phthalocyanine shown in FIG. 7 obtained in Synthesis Example 1 was milled in THF and further washed with methanol to obtain a Bragg angle of 2θ of 9.1° as shown in FIG.
A titanyl phthalocyanine having a peak at 27.2° was obtained. An exothermic peak was observed at 300° C. in differential thermal analysis of this titanyl phthalocyanine.

Synthesis Example 3 65 g of o-phthalodinitrile and 5 g of α-chlornaphthalene
After dropping 14.7 ml of titanium tetrachloride into 00 ml of the mixture under a nitrogen stream, the temperature was gradually raised to 200°C, and the reaction temperature was maintained at 200°C and stirred for 3 hours to complete the reaction. Thereafter, the mixture was left to cool, and the crystals precipitated at room temperature were collected by filtration. The crystals were washed several times with α-chloronaphthalene and methanol, and then stirred in ammonia water at 80° C. to complete hydrolysis. The crystals were treated with sulfuric acid in the same manner as in Synthesis Example 1, and then the wet paste was treated in o-dichlorobenzene at 60°C to obtain blue crystals. This crystal is
The titanyl phthalocyanine of the present invention has peaks at 9.5° and 27.2° of Bragg angle 2θ in the line diffraction spectrum as shown in FIG. 9, and has an exothermic peak at 285°C in differential thermal analysis. Ta.

Synthesis Example 4 65 g of o-phthalodinitrile, 14.7 m of titanium tetrachloride
1 and 500 ml of quinoline were mixed and reacted at 200° C. for 5 hours. The crystals were heated and washed with quinoline and methanol, and then washed repeatedly with hot water until the filtrate became neutral. Synthesis Example 1
After being treated with sulfuric acid in the same manner as above, the wet paste was treated with o-dichlorobenzene to obtain blue crystals. This crystal is the first
As shown in Figure 0, 9.5°, 27.2 in X-ray diffraction
In the crystalline titanyl phthalocyanine of the present invention having a peak at 277° C., an exothermic peak was observed at 277° C. in thermal differential analysis.

Comparative Synthesis Example 1 29.2 g of 1,3-diiminoisoindoline, 200 ml of o-dichlorobenzene and 20.4 g of titanium tetrabutoxide were mixed and refluxed for 5 hours under a nitrogen stream. After cooling to room temperature, the precipitated crystals were collected by filtration and washed several times with o-dichlorobenzene and methanol. The crystals were further stirred in a 1% aqueous hydrochloric acid solution for 2 hours, washed several times with 200 ml of pure water and further with methanol, and then dried to obtain 25.7 g of reddish-purple crystals.

Next, the crystals were treated with sulfuric acid in the same manner as in Synthesis Example 1, and the wet paste was then treated with 1,2-dichloroethane to obtain blue crystals. As shown in Fig. 11, this crystal has a Bragg angle of 2θ of 27 in the X-ray diffraction spectrum.
．． Although the titanyl phthalocyanine had a peak at 2°, an exothermic peak was observed at 265°C in differential thermal analysis.

Comparative Synthesis Example 2 After drying the wet paste obtained in Synthesis Example 1, it was milled using methyl cellosolve in a temperature range of 100 to 120°C. The titanyl phthalocyanine thus obtained has a Bragg angle 2θ of 7.
It was a B-type titanyl phthalocyanine having peaks at 5° and 28.6°. This B-type titanyl phthalocyanine did not show a clear exothermic peak in the range of 150 to 400°C in thermal differential analysis. Comparative Synthesis Example 3 The crude crystals obtained in Synthesis Example 3 before being treated with sulfuric acid were dry ground using a mortar to obtain amorphous crystals. Next, the crystals were stirred in methanol, filtered, and milled using octane as a solvent to obtain blue crystals. As shown in FIG. 13, this crystal is 9.0°, 27.
Although the crystal form of the present invention had a peak at 2°, an exothermic peak was observed at 361°C in thermal differential analysis.

Example 1 Titanyl phthalocyanine 1 of the present invention obtained in Synthesis Example 1
Part, silicone resin (KR-52
40, 15% xylene, butanol solution (manufactured by Shin-Etsu Chemical Co., Ltd.) solid content 1 part, 100% methyl ethyl ketone as dispersion medium
The mixture was dispersed using a sand mill to obtain a dispersion. This was applied onto a polyester base coated with aluminum using a wire bar to form a carrier generation layer having a thickness of 0.2 μm.

Next, 1 part of carrier transport substance (1), 1.3 parts of polycarbonate resin "Iupilon Z200" (manufactured by Mitsubishi Gas Chemical) and a trace amount of silicone oil "KF-
54'' (manufactured by Shin-Etsu Chemical Co., Ltd.) dissolved in 10 parts of 1.2 dichloroethane was applied using a blade coater, and after drying,
A carrier transport layer with a thickness of 20 μm was formed. The photoreceptor thus obtained is referred to as sample 1.

Example 2 In Example 1, the titanyl phthalocyanine obtained in Synthesis Example 2 was used instead of the titanyl phthalocyanine obtained in Synthesis Example 2, and the carrier transport substance (1) was replaced with carrier transport substance (1). A photoreceptor was prepared in exactly the same manner as in Example 1, except that Example 22) was used. This is called sample 2.

Example 3 3 parts of copolyamide "Laccamide 5003" (manufactured by Dainippon Ink Co., Ltd.) was heated and dissolved in 100 parts of methanol.
．． After filtering through a 6 μm filter, it was coated on an aluminum drum by a penetrating coating method to form a subbing layer with a thickness of 0.5 μm.

On the other hand, 3 parts of the titanyl phthalocyanine of the present invention obtained in Synthesis Example 3, 3 parts of silicone resin as a binder resin (KR-5240, 15% xylene, butanol solution, manufactured by Shin-Etsu Chemical Co., Ltd.) solid content, and a dispersion medium. A solution obtained by dispersing 100 parts of methyl isobutyl ketone using a sand mill was applied onto the previous undercoat layer by a penetration coating method to form a carrier generation layer having a thickness of 0.2 μm.

Next, 1 part of carrier transport substance (4), 1.5 parts of polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and a trace amount of silicone oil "KF-
54'' (manufactured by Shin-Etsu Chemical Co., Ltd.) to 1,2-dichloroethane 10
After coating the solution dissolved in the sample using a blade coater and drying, a carrier transport layer having a thickness of 20 μm was formed. The photoreceptor thus obtained is referred to as sample 3.

Example 4 In Example 3, titanyl phthalocyanine obtained in Synthesis Example 4 was used instead of titanyl phthalocyanine obtained in Synthesis Example 3, and carrier transport substance (22) was used in place of carrier transport substance (4). ) A photoreceptor was prepared in the same manner as in Example 3 except that the photoreceptor was used. This will be referred to as comparative sample 4.

Comparative Example 1 A photoreceptor was prepared in the same manner as in Example 1, except that the titanyl phthalocyanine obtained in Comparative Synthesis Example 1 was used instead of the titanyl phthalocyanine obtained in Synthesis Example 1. did. This will be referred to as comparative sample (1).

Comparative Example 2 In Example 1, instead of using titanyl phthalocyanine obtained in Synthesis Example 1, 150 obtained in Comparative Synthesis Example 2 was used.
A photoreceptor was prepared in the same manner as in Example 1, except that B-type titanyl phthalocyanine, which does not have a clear exothermic peak in the range of -400°C, was used. This will be referred to as comparative sample (2).

Comparative Example 3 A photoreceptor was prepared in the same manner as in Example 1, except that titanyl phthalocyanine obtained in Comparative Synthesis Example 3 was used instead of the titanyl phthalocyanine obtained in Synthesis Example 1. . This will be referred to as comparative sample (3).

Evaluation The samples obtained as described above were evaluated as follows using Paper Analyzer EPA 8100 (manufactured by Kawaguchi Electric Co., Ltd.). First, corona charging was performed for 5 seconds under the condition of -8 μA, and the surface potentials Va and Vi were determined immediately after charging. Subsequently, exposure was performed so that the surface illuminance was 2 (lux), and the surface potential was set to 1/Vi. Exposure amount E1 required to
/2 was calculated. Further, the dark decay rate D was determined from the formula D=100(Va-Vi)/Va (%). Further, the temperature at which the exothermic peak appears in the differential analysis of each sample is expressed as T. Table 1 shows the results.
It was shown to.

[0060]

[Table 1]

[0061] As described above, the crystalline titanyl phthalocyanine of the present invention has superior chargeability and higher sensitivity than other crystalline titanyl phthalocyanines, such as those found in comparative sample (2). I understand.

Next, a normal Carlson process was carried out using these photoreceptors, and the difference in surface potential [ΔVb] immediately after charging between the initial stage and after 10,000 cycles, and the residual potential after 10,000 cycles [ΔVb] were determined.
Vr] was calculated. In addition, the surface potential [V
w], the initial value and the value after 10,000 times were determined. These results are shown in Table-2.

[0063]

[Table 2]

As can be seen from the results, the electrophotographic photoreceptor containing the titanyl phthalocyanine of the present invention has particularly excellent potential stability during repeated use.

[0065]

Effect of the invention: An electrophotographic image containing titanyl phthalocyanine which has a peak at 27.2° of Bragg angle 2θ in the X-ray diffraction spectrum of the present invention and has an exothermic peak at 275°C or more and 350°C or less in thermal differential analysis. The photoreceptor maintains good charging properties and high sensitivity characteristics. In addition, this electrophotographic photoreceptor has particularly excellent potential stability during repeated use, so that it can be used as a photoreceptor suitable for image formation in printers, copying machines, and the like.

[Brief explanation of the drawing]

FIG. 1 to FIG. 6 are cross-sectional views showing specific examples of the layer structure of the photoreceptor of the present invention.

FIG. 2 is an X-ray diffraction spectrum of the titanyl phthalocyanine of the present invention obtained in Synthesis Example 1.

FIG. 3 is an X-ray diffraction spectrum of the titanyl phthalocyanine of the present invention obtained in Synthesis Example 2.

FIG. 4 is an X-ray diffraction spectrum of the titanyl phthalocyanine of the present invention obtained in Synthesis Example 3.

FIG. 5 is an X-ray diffraction spectrum of the titanyl phthalocyanine of the present invention obtained in Synthesis Example 4.

FIG. 6 is an X-ray diffraction spectrum of titanyl phthalocyanine obtained in Comparative Synthesis Example 1.

FIG. 7 is an X-ray diffraction spectrum of titanyl phthalocyanine obtained in Comparative Synthesis Example 2.

FIG. 8 is an X-ray diffraction spectrum of titanyl phthalocyanine obtained in Comparative Synthesis Example 3.

[Explanation of symbols]

1... Conductive support 2... Carrier generation layer 3... Carrier transport layer

Claims (1)

[Claims] [Claim 1] In the X-ray diffraction spectrum, CuK
2 of the Bragg angle 2θ for α rays (wavelength 1.541 Å)
An electrophotographic photoreceptor comprising titanyl phthalocyanine having a peak at 7.2±0.2° and an exothermic peak at 275° C. or higher and 350° C. or lower in differential thermal analysis.