JPH01207754A - Organic photosensitive body - Google Patents

Abstract

PURPOSE:To enhance general electrophotographic characteristics, especially, sensitivity and charge retaintivity by using an organic type electric charge generating material reduced in electric conductivity to <=50muOMEGA/cm measured by dispersing 1g of said material in 100ml of deionized water. CONSTITUTION:The organic charge generating material to be used for the charge generating material of the photosensitive body is reduced in electric conductivity to <=50muOMEGA/cm measured by dispersing 1g of said material in 100ml of deionized water; it is sufficiently washed with an organic solvent, such as tetrahydrofuran or dimethylformamide, then sufficiently washed with water, further washed with the deionized water or distilled water, and dried in vacuum to remove inorganic impurities and to reduce its conductivity, thus permitting the content of the inorganic impurities in the organic charge generating material to be reduced, and the general electrophotographic characteristics, especially, sensitivity and charge retaintivity to be enhanced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a photoreceptor in which a photosensitive layer containing a charge-generating material and a charge-transporting material is provided on a conductive support. , relates to a photoreceptor having characteristics in the charge generating material contained in the photoreceptor layer.

[Prior Art] Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known as materials constituting the photosensitive layer of a photoreceptor used for electrophotography and the like.

Although these inorganic photoconductive materials have many advantages, such as less charge dissipation in the dark or the ability to quickly dissipate charge by light irradiation, they also have various disadvantages. ing. For example, selenium-based photoreceptors require difficult manufacturing conditions, are expensive to manufacture, and must be handled with care because they are susceptible to heat and mechanical shock. In addition, cadmium sulfide photoreceptors do not provide stable sensitivity in humid environments, and the dye added as a sensitizer causes charging deterioration due to corona charging and photobleaching due to exposure to light, so it is difficult to obtain stable sensitivity over a long period of time. It has the disadvantage of not being able to provide stable characteristics.

On the other hand, the use of various organic photoconductive polymers including polyvinylcarbazole as materials constituting the photosensitive layer has also been considered. However, although these organic photoconductive polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film formability and light weight, they still lack sufficient sensitivity, durability, and stability due to environmental changes. In this respect, it was inferior to inorganic photoconductive materials.

Therefore, in recent years, various research and developments have been carried out to solve the drawbacks and problems of these photoreceptors, and the charge generation function and charge transport function of the photoconductive function are divided into separate substances. Laminated or dispersed functionally separated photoreceptors have been developed.

Such functionally separated photoreceptors have a wide range of materials to choose from, and can combine the best materials in terms of electrophotographic properties such as charging characteristics, sensitivity, residual potential, repeatability, and printing durability. This has the advantage of being able to provide a high-performance photoreceptor, and since it can be produced by coating, it is extremely productive and can provide an inexpensive photoreceptor.Moreover, it is possible to select an appropriate charge-generating material. Another advantage was that the sensitive wavelength range could be controlled freely.

For such a functionally separated photoreceptor, examples of charge generating materials include phthalocyanine pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, helinone pigments, indigo dyes, thioindigo dyes, squaric acid methane dyes, etc. organic pigments and dyes, as well as selenium, selenium/arsenic, selenium/tellurium, cadmium sulfide, zinc oxide,
It is said that inorganic materials such as amorphous silicon can be used.

[Problems to be Solved by the Invention] However, even in the functionally separated photoreceptor as described above, it has not been possible to obtain a photoreceptor that is fully satisfactory in terms of overall electrophotographic characteristics such as sensitivity and charge retention ability.

In addition, in recent years, such photoreceptors have been used in reader printers, laser printers, etc. to form images by reversal development.
In this case, there were problems such as the occurrence of minute black spots, especially in blank areas.

The inventor has conducted intensive research on such functionally separated photoreceptors and found that when an organic charge generation material is used as the charge generation material contained in the photosensitive layer,
This organic charge-generating material has a great influence on the overall electrophotographic properties of the photoreceptor, such as sensitivity and charge retention ability, and in particular,
They have discovered that inorganic ionic impurities contained in this charge-generating material are one of the major factors.

This invention was made in view of the above circumstances,
The aim is to use an organic charge-generating material with excellent dispersibility and coating properties, and to have excellent electrophotographic properties in general, especially sensitivity and charge retention, and to be used in reader printers, laser printers, etc. It is an object of the present invention to provide an organic photoreceptor that suppresses the occurrence of minute black spots in blank areas even when developed, and provides good images.

[Means for Solving the Problems] An organic photoreceptor according to the present invention is a photoreceptor in which a photosensitive layer containing a charge-generating material and a charge-transporting material is provided on a conductive support. , using an organic charge generating material, the conductivity measured by dispersing 1 g of this organic charge generating material in 100 ml of deionized water is 50 μΩ/
It was decided to use the one whose diameter was less than cm.

Here, various known organic charge generating materials can be used as the charge generating material, such as bisazo pigments, triarylmethane pigments, thiazine dyes, oxazine dyes, xanthine dyes, etc. dyes, cyanine pigments, styryl pigments, biryllium dyes, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments Examples include pigments, phthalocyanine pigments, etc., but are not particularly limited to these.

In the present invention, when using the organic charge generating material as described above as a charge generating material for a photoreceptor, the organic charge generating material is sufficiently washed with an organic solvent such as tetrahydrofuran or dimethylformamide, and then
This is thoroughly washed with water, further washed with deionized water, distilled water, etc., and dried under reduced pressure to remove inorganic ionic impurities.
The purpose was to reduce the conductivity of the layer.

In the present invention, 1 g of the organic charge generating material whose conductive layer has been reduced as described above is weighed, poured into 100 ml of deionized water, and dispersed in an ultrasonic cleaner for 5 minutes. As a result of measuring the conductivity of a dispersion kept at 25° C., the conductivity of the dispersion was determined to be 50 μΩ/cm or less.

The reason for using a conductive layer with a conductive layer of 50 μΩ/cn+ or less is that if a photoreceptor with a conductive layer larger than 50 μΩ/cm is used, the sensitivity and charge retention ability will deteriorate, especially in the dark. The attenuation increases significantly, the repeatability deteriorates significantly, the dispersibility and coating properties of the organic charge generating material also deteriorate, and in addition, charge injection due to inorganic ionic impurities contained in the organic charge generating material deteriorates. This is because the number of partial discharges and black spots during reverse development increases.

For this reason, it is generally preferable for the organic charge generating material to be used to have a conductive layer with a small value, and in order to sufficiently improve each characteristic such as sensitivity and charge retention capacity, the conductive layer must be 20μΩ/or less. , more preferably 10μΩ/c
Try to use one that is less than m. However, in order to reduce the size of the conductive layer, there are problems such as a large amount of time and effort required for cleaning.
It is preferable to adjust it to approximately μΩ/cm.

In the organic photoreceptor according to the present invention, a coating solution obtained by dispersing the organic charge-generating material as described above in a suitable binder resin can be coated using a dip coating method, a spray coating method, or a spinner coating method. , a blade coating method, a roller coating method, a Mayer bar coating method, and the like are used to coat the conductive support on the conductive support, and the coated material is dried.

Here, the conductive support in this photoreceptor may be a sheet or drum-shaped foil or plate of copper, aluminum, silver, iron, nickel, etc., or a plastic film etc. made of these metals by vacuum evaporation, Use a layer attached by electroless plating, etc., or a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide formed on a support such as paper or plastic film by coating or vapor deposition. be able to.

Further, examples of the binder resin used together with the above-mentioned organic charge generating material include saturated polyester resin, polyamide resin, and acrylic resin.

Ethylene-vinyl acetate copolymer, ionically crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polyarylate, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester,
Thermoplastic binders such as polyimide, styrene resin, polyacetal resin, phenoxy resin, thermosetting binders such as epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin, xylene resin, alkyd resin, thermosetting acrylic resin, etc. Photoconductive resins such as photoresist, photocurable resin, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, etc. can be used.

Then, the above organic charge generating material is mixed with these binder resins, alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide, N,N -Amides such as dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogens such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. A photosensitive coating liquid prepared by dispersing or dissolving in organic solvents such as hydrogenated hydrocarbons or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzene is coated on the above-mentioned conductive support. and dry it to form a photosensitive layer.

In addition, in the case of a multilayer organic photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support, the above organic charge generation material is added to a resin in a solution in which a binder resin is dissolved. A coating solution prepared by dispersing the mixture in a mixing ratio of 5=1 to 1:5 is applied onto a conductive support and dried to form a charge generation layer. In this case, it is desirable that the charge generation layer has a thickness of 0.01 to 2 μm, preferably 0.1 to 1 μm.

Next, a solution prepared by dissolving a charge transport material and a binder resin in a suitable solvent is applied onto the thus formed charge generation layer, and the solution is dried to form a charge transport layer. In this case, the charge transport layer is formed to have a thickness of 3 to 40 μm, preferably 5 to 25 μm. Further, the content of the charge transport material in the charge transport layer is as follows: binder resin 1
0.02 to 2 parts by weight, preferably 0.5 parts by weight
~1.2 parts by weight. Note that two or more charge transport materials may be used in combination, and in the case of a polymeric charge transport material that itself can be used as a binder, there is no need to use another binder resin.

Here, charge transport materials used for forming the charge transport layer include hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenyl Various compounds such as amine compounds, tetraphenylbenzidine compounds, and azine compounds can be used. in particular,
For example, carbazole, N-ethylcarbazole, N-vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2.3-benzochrysene, 3.4
-Benzopyrene, fluorene, 1,2-benzofluorene, 4-(2-fluorenylazo)resorcinol, 2
-p-anisoleaminofluorene, p-diethylaminoazobenzene, cation, N,N-dimethyl-p-phenylazoaniline, p-(dimethylamino)stilbene, 1,4-bis(2-methylstyryl)benzene, 9
-(4-diethylaminostyryl)anthracene, 2,
5-bis(4-diethylaminophenyl)-1,3,5
-Oxadiazole, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-phenyl-5-pyrazolone, 2-(m-naphthyl)-3- Phenyloxazole, 2-(p-diethylaminostyryl)-6-ethylaminobenzoxazole, 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)
Phenylmethane, 1,1-bis(4-N,N-diethylamino-2-ethylphenyl)hebutane, N,N-diphenylhydrazino-3-methylidene-1O-ethylphenoxazine, N,N-diphenylhydrazino -3-methylidene-10-ethylphenothiazine, 1,1°2.2
-Tetrakis-(4-N,N-diethylamino-2-ethylphenyl)ethane, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N-diphenylhydrazone, N-ethylcarbazole-N -Methyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N,N −
Diphenylamino-β-phenylstilbene, α-phenyl-4-N, N-diphenylaminostilbene, 1,
Charge transporting substances such as 1-bisdiethylaminophenyl-4,4-diphenyl-1,3-butadiene are used alone or in combination of two or more.

Note that here, a charge generation layer is formed on a conductive support,
Although a photoreceptor in which a charge transport layer is provided thereon has been described, it may be conversely formed in which a charge transport layer is formed on a conductive support and a charge generation layer is formed thereon.

Further, in any of the photoreceptors obtained as described above, an adhesive layer, an intermediate layer, and a surface protection layer can be provided as necessary.

Here, the materials used to form the intermediate layer include polymers such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, and polyvinyl alcohol as they are, or polymers in which low-resistance compounds such as tin oxide and indium oxide are dispersed. , or a vapor-deposited film of aluminum oxide, zinc oxide, silicon oxide, etc. is suitable, and the film thickness is 1.
It is desirable to form the thickness to be less than μm.

Further, suitable materials for the surface protective layer include polymers such as acrylic resins, polyaryl resins, polycarbonate resins, and urethane resins as they are, or those in which low-resistance compounds such as tin oxide and indium oxide are dispersed.

Furthermore, an organic plasma polymerized film can also be used, and this organic plasma polymerized film can also contain oxygen, nitrogen, halogen, and atoms of Groups I and V of the periodic table, if necessary. .

Note that it is desirable that the surface protective layer has a thickness of 5 μm or less.

[Function] As mentioned above, in the organophotoreceptor according to the present invention,
The organic charge generating material used as the charge generating material has an electrical conductivity of 50 μΩ/cm or less as measured by dispersing 1 g of the organic charge generating material in 100 ml of deionized water. There are few inorganic ionic impurities in the organic charge-generating material, and the electrophotographic properties such as sensitivity and charge retention capacity do not deteriorate, resulting in a photoreceptor that has excellent electrophotographic properties in general, especially sensitivity and charge retention capacity. You will be able to get it.

In addition, this organic charge-generating material has good dispersibility and coating properties, allowing it to be coated uniformly on a conductive support, as well as reducing charge injection and partial discharge caused by inorganic ionic impurities. The occurrence of black spots and white spots during development is suppressed, making it possible to obtain good images. For this reason, this organic photoreceptor is used not only as a photoreceptor for electrophotographic copying machines but also for laser printers, CRT printers,
It can also be widely used in electrophotographic application fields such as electrophotographic plate making systems and photoconductive toners.

[Example] Next, specific examples of the present invention will be described, and comparative examples will be given to clarify that the examples of the present invention are superior.

Methods 1 to 3 and Examples 1 to 3 In these cases, 3-hydroxy-2-naphthoanilide (naphthol AS) 2 is used in preparing the organic charge generating material used as the charge generating material.
．． 6 parts by weight and 3.0 parts by weight of the bisazo compound represented by the following chemical formula [I] in 20 parts by weight of N,N-dimethylformamide.
0 ml, add 3 g of sodium acetate to this and add 15 g of water.
A solution dissolved in 0 ml was added dropwise at 10 to 20°C over about 30 minutes.

[■] After stirring this at room temperature for 3 hours, the precipitated crystals were collected by filtration.

Then, the crude crystal cake thus obtained was DM
After dispersing in 400 ml of F and stirring at room temperature for 3 hours, the crystals were filtered again, and this operation was repeated three times.

In Example 1, the bisazo pigment used as the organic charge-generating material thus obtained was dispersed in 400 mI of deionized water, stirred at room temperature for 3 hours, and then the crystals were collected by filtration again. This operation was repeated three times, and the crystals were washed with deionized water a total of four times, and finally the crystals collected by filtration were dried under reduced pressure at 120°C.

Further, in the case of Example 2, the above-mentioned washing with deionized water was performed 5 times, and in the case of Example 3, the washing was performed 6 times.

On the other hand, in Comparative Example 1, the above-mentioned washing with deionized water was not performed, in Comparative Example 2 it was washed once, and in Comparative Example 3 it was washed twice.

Then, 11 g of each of the crystals of Examples 1 to 3 and Comparative Examples 1 to 3 obtained in this way was weighed, and each of them was poured into 100 ml of distilled water, and the crystals were washed in an ultrasonic cleaner for 50 minutes.
Regarding the dispersion liquid that was kept at 25°C after being dispersed for a minute,
The conductivity of each was measured using a conductivity scale. This result is
The results were as shown in Table 1 below.

Table 1 When forming a photoreceptor using these organic charge generating materials, an outer diameter of 80 m is used as a conductive support.
First, polyamide resin (Elvamide 8061) was applied onto the aluminum drum.
Apply a 1% methanol solution (manufactured by DuPont), and
An intermediate layer of .mu.m was formed.

Next, in forming a charge generation layer on the conductive support using each of the organic charge generation materials obtained as described above, 0.00% of the organic charge generation material was used.
1 part by weight and 0.1 part by weight of polyester resin (Byron 200 manufactured by Toyobo ■) were added to 10 parts by weight of cyclohexanone, dispersed using a sand grinder, and each dispersion coating solution was applied onto a conductive support. , and then dried to form a charge generation layer having a thickness of 3 g/m'' each.

In forming a charge transport layer on each charge generation layer thus formed, a styryl compound represented by the following chemical formula [11] was used as a charge transport material.

A coating solution prepared by dissolving 10 parts by weight of this styryl compound and 10 parts by weight of polycarbonate resin in 100 parts by weight of tetrahydrofuran is applied onto each of the charge generation layers described above and dried to form a charge transport film with a thickness of 20 μm. A layer was formed on each of the above charge generation layers to produce a laminated organic photoreceptor in which a charge generation layer and a charge transport layer were laminated on a conductive support.

Here, in producing each photoreceptor as described above, the coating properties and dispersibility of the dispersion coating liquid of each organic charge generating material used in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated. did.

Next, using a copying machine EP-470Z manufactured by Minolta Camera ■, each of the photoconductors prepared as described above was corona charged, and the initial surface potential Vo of each photoconductor was set to -750V.
, the half-reduced exposure amount E1/2 (lux-sec) required to bring this initial surface potential Vo to 172, and the dark decay rate DDR, (%) of the initial surface potential VO when left in a dark place for 5 seconds. and the half-decreased exposure amount E, 72' (lux-s) after continuous copying of 1000 sheets.
ee) were also measured.

Further, black spots in the blank area and white spots in the black solid area were also evaluated when reverse development was performed with the initial surface potential VO set to -750V and the development bias Vb set to -500V.

These results are summarized in Table 2 below. In addition, in the same table, regarding white spots and black spots in the image, coating properties and dispersibility of the dispersion coating liquid, good cases are indicated by ○, very good cases are indicated by Δ, and poor cases are indicated by ×. did.

(The following are blank spaces) 4-6 and 45 In preparing the organic charge-generating material used as the charge-generating material, 10.2 parts by weight of 0-phthalodinitrile and 3.8 parts by weight of titanium tetrachloride are used. The suspension was suspended in 200 ml of α-chloronaphthalene, heated to 210-215°C, and reacted for 3 hours.

After cooling the reaction mixture and filtering the crystals,
This was washed with acetone and methanol and dried, and the crystals were slurried twice in refluxing dimethylformamide, filtered while hot, and washed with acetone.

5 parts by weight of titanyl phthalocyanine thus obtained was dissolved in 50 ml of concentrated sulfuric acid while cooling, and this solution was added to 500 ml of ice water with stirring, and the precipitated blue crystals were collected by filtration.

Next, the crystals were dispersed in 400 ml of acetone,
After stirring at room temperature for 3 hours, the crystals were filtered again, and this operation was repeated three times to prepare a phthalocyanine pigment to be used as an organic charge generating material.

In Example 4, 4 g of the phthalocyanine pigment thus obtained was dispersed in 400 ml of deionized water, stirred at room temperature for 3 hours, and then the crystals were filtered again, and this operation was repeated twice. After repeating the process and washing with deionized water three times in total, the crystals collected by filtration were
It was dried under reduced pressure at ℃.

Further, in the case of Example 5, the above-mentioned washing with deionized water was carried out four times, and in the case of Example 3, the washing was carried out five times.

On the other hand, in Comparative Example 4, the above-mentioned washing with deionized water was not performed, and in Comparative Example 5, it was performed twice.

Then, 1 g of each of the crystals of Examples 4 to 6 and Comparative Examples 4 and 5 obtained in this way was weighed out, each of them was poured into 100 ml of distilled water, and dispersed in an ultrasonic cleaner for 5 minutes. Afterwards, for the dispersion kept at 25°C,
The conductivity of each was measured using a conductivity scale. This result is
The results were as shown in Table 2 below. Note that by washing with water twice, the pH of the washing water became 7.

Table 2 When forming a photoreceptor using these organic charge generating materials, an aluminum drum with an outer diameter of 80 nm+m was used as a conductive support, as in the case described above.

Then, phenol resin (
A 1% methanol solution of Pryophen J325 (manufactured by Dainippon Ink ■) was applied to form an intermediate layer of 0.1 μm.

Next, in forming a charge generation layer on the conductive support using each of the organic charge generation materials obtained as described above, 0.00% of the organic charge generation material was used.
1 part by weight and 0.0 parts of butyral resin with a degree of butylation of 65%.
1 part by weight of cyclohexanone was added to 10 parts by weight of cyclohexanone, dispersed with a sand grinder, each dispersion coating solution was applied onto a conductive support, and dried to obtain a film thickness of 0.3 g/♂.
A charge generation layer was formed.

In forming a charge transport layer on each charge generation layer thus formed, an enamine compound represented by the following chemical formula [I[I] was used as a charge transport material.

A coating solution prepared by dissolving 10 parts by weight of this enamine compound and 10 parts by weight of polycarbonate resin in 100 parts by weight of tetrahydrofuran is applied onto each of the charge generation layers described above and dried to form a charge transport layer with a thickness of 20 μm. A layer was formed on each of the above charge generation layers to produce a laminated organic photoreceptor in which a charge generation layer and a charge transport layer were laminated on a conductive support.

Then, in the same manner as above, the coating properties and dispersibility of the dispersion coating liquids of each organic charge generating material used in Examples 4 to 6 and Comparative Example 4.5 were evaluated, and the Minolta camera (Half-reduced exposure amount E I/2 (1ux-q) and 5 when corona charging each photoreceptor using a copier EP-4702 manufactured by Tsutsu Co., Ltd. and setting the initial surface potential Vo on each photoreceptor to -750V The dark decay rate DDR5 (%) when left in a dark place for seconds was measured, and the half-decrease exposure M after continuous copying of 1000 sheets was measured.
E tz2'(lux-w) was also measured.

Furthermore, black spots in the blank area and white spots in the black solid area were also evaluated when reverse development was performed with the initial surface potential Vo set to -750V and the development bias Vb set to -500V.

These results are summarized in Table 3 below. In addition, in the same table, regarding the white spots and black spots in the image, the coating properties and dispersibility of the dispersion coating liquid, good cases are indicated by ○, very good cases are indicated by Δ, and poor cases are indicated by ×. Na.

(Left below) As is clear from the results shown in Tables 1 and 2,
As in each embodiment of the present invention, the conductivity of the organic charge generating material used in the charge generating material is 50μ when measured by dispersing 1g of the organic charge generating material in 100ml of distilled water.
Ω/cm or less, the coating liquid has better coating properties and dispersibility than the comparative example using an organic charge-generating material with high conductivity, and the conductive support The charge generation layer is now uniformly formed on the body.

In addition, the photoreceptors of each example using the organic charge-generating material with low conductivity have lower half-life exposure amount El/□ and dark decay rate DDR than the photoreceptors of each comparative example. It has excellent sensitivity and charge retention ability, and in addition, there is little change in the half-life exposure amount El/2' after 1000 copies have been made, making it possible to use it stably for a long period of time.

Furthermore, in the photoreceptors of each example, the occurrence of black spots in white paper areas and white spots in solid black areas during reversal development was less than that of each comparative example, and was less likely to occur in reader printers or lasers. High-quality images can now be obtained even when used in printers, etc.

In addition, when comparing the products of each example, photoreceptors using organic charge generating materials whose conductivity was 20 μΩ/cm or less when measured by dispersing 1 g of organic charge generating materials in 100 ml of distilled water was excellent overall.

[Effects of the Invention] As described in detail above, the present invention provides an organic charge generating material having an electrical conductivity of 50 μΩ/Cl or less when measured by dispersing 1 g of the organic charge generating material in 100 rnl of deionized water. As a result, inorganic ionic impurities in the organic charge-generating material are reduced, and a photoreceptor with excellent overall electrophotographic properties, particularly sensitivity and charge retention ability, can be obtained.

In addition, coating liquids using such organic charge-generating materials have good coating properties and dispersibility, and the organic charge-generating materials are uniformly dispersed on the conductive support. Charge injection and partial discharge due to impurities are also reduced, and the occurrence of black and white spots during reverse development is suppressed, making it possible to obtain good images.

As a result, the organic photoreceptor according to the present invention can be suitably used in electrophotographic application fields such as laser printers, CRT printers, electrophotographic plate making systems, and photoconductive toners, in addition to electrophotographic copying machines. Ta.

Claims (1)

[Claims] 1. In a photoreceptor in which a photosensitive layer containing a charge-generating material and a charge-transporting material is provided on a conductive support, an organic charge-generating material is used as the charge-generating material, and 1 g of this organic charge-generating material is used. An organic photoreceptor characterized in that an organic photoreceptor is used that has an electrical conductivity of 50 μΩ/cm or less when measured after being dispersed in 100 ml of deionized water.