JPH01191883A - Electrophotographic process - Google Patents

Abstract

PURPOSE:To lower the relative humidity at and under a high temp. and high humidity and to prevent image blurring, image thinning, dew condensation at a low temp. and scumming at and under a low temp. and low humidity by maintaining a photosensitive body at a specific temp. or below. CONSTITUTION:The relative humidity at and under the high temp. and high humidity is lowered if the photosensitive having an inorg. or org. photosensitive layer is maintained at >=50 deg.C and <=80 deg.C at which no adverse influence is exerted on an org. material and toner. The generation of the image blurring, the image thinning, etc., at the time of iterative use in the environment at and under the high temp. and high humidity is thereby prevented. Further, the generation of the dew condensation at the low temp. and the scumming at and under the low temp. and low humidity are prevented and the stable image having no deterioration in the image quality is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to improvements in electrophotographic processes.

[Prior art]

In recent years, photoreceptors used in electrophotographic copying machines have begun to be made of organic photosensitive materials, which have the advantages of low cost, productivity, and non-polluting properties.

Organic electrophotographic photoreceptors include photoconductive resins such as polyvinylcarbazole (PVK), and PVK-TNF.
There are charge transfer complex type photoreceptors represented by (2,4,7 trinitrofluorenone), pigment dispersion types represented by phthalocyanine binders, and functionally separated type photoreceptors that use a combination of a charge generating substance and a charge transporting substance. In particular, functionally separated type photoreceptors are attracting attention.

When such an organic photoreceptor is applied to the Carlson process, it has low chargeability and poor charge retention (high dark decay), and these characteristics deteriorate significantly with repeated use, causing problems such as It has the drawbacks of density unevenness, fog, and background smearing in the case of reverse development.

That is, the chargeability of organic photoreceptors decreases due to pre-exposure fatigue. This pre-exposure fatigue is mainly caused by light absorbed by the charge-generating material, so the longer the charges generated by light absorption remain in the photoconductor in a mobile state, the more the number of charges increases. It is thought that the lower the chargeability becomes, the more the chargeability decreases due to pre-exposure fatigue. In other words, even if a charging operation is performed while the charge generated by light absorption remains, the surface charge will be neutralized by the movement of the remaining carriers, so the surface potential will increase until the residual charge is consumed. do not. Therefore, the increase in surface potential is delayed by the amount of pre-exposure fatigue, and the apparent charge level 4 becomes lower.

As a method to improve these drawbacks, an inorganic material such as SiOSlolA is used between the support and the charge generation layer.

Methods such as vapor deposition, sputtering, and anodic oxidation are known, and Ui, O, etc. are included in the charge generation layer (Japanese Unexamined Patent Publication No. 55-142354), and metal powder is also included in the charge generation layer. It is also known to contain (
(Japanese Patent Application Laid-Open No. 60-214364).

In addition, polyamide resin (Japanese Unexamined Patent Publication No. 58-30
No. 757, JP-A No. 58-98739), alcohol-soluble nylon resin (JP-A No. 60-196766)
Publication No.), water-soluble polyvinyl butyral resin (Japanese Unexamined Patent Publication No. 6
0-232553) and polyvinyl butyral resin (Japanese Unexamined Patent Publication No. 106549/1982).

However, with regard to the deterioration of chargeability and charge retention due to repeated use, improvement measures on the photoreceptor side have not been sufficient to provide a photoreceptor.

JP-A-51-111338 discloses that if As, Ss, and a photoreceptor are maintained at a temperature 10 to 30% higher than room temperature and not exceeding 40°C, the rate of fatigue (dark decay) will be slowed down. is disclosed.

On the other hand, in the operating environment of a copying apparatus, under high temperature and high humidity conditions, single image blurring, image distortion, etc. occur, and at low temperatures, there are problems such as dew condensation on the photoreceptor and scumming.

Regarding this environmental dependence, JP-A-61-7843 discloses that the relative humidity of the photoreceptor under high temperature and high humidity can be reduced by heating the support of the photoreceptor layer at a relatively low temperature using a planar heating element. , JP-A-62-121483 discloses a method of blowing hot or cold air onto a photoreceptor, which is a method that can prevent dew condensation on the photoreceptor at low temperatures and prevent deterioration of the photoreceptor at high temperatures. has been disclosed, but the method was not necessarily satisfactory. This tendency is particularly strong when a highly durable electrophotographic photoreceptor in which a protective layer is provided on the photosensitive layer is used, and further improvements have been strongly desired.

〔the purpose〕

The present invention reduces relative humidity under high temperature and high humidity conditions and reduces image blur.
An object of the present invention is to provide an electrophotographic process that can prevent image distortion, dew condensation on a photoreceptor at low temperatures, and background smear at low temperatures and humidity.

〔composition〕

According to the present invention, in an electrophotographic process including a step of charging and exposing an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support to form an electrostatic latent image, the photoreceptor is always kept at 50°C. Provided is an electrophotographic process characterized by the above-mentioned retention.

The inventors of the present invention have conducted studies to solve the conventional drawbacks of electrophotographic photoreceptors in which at least a photosensitive layer is provided on a conductive support. The present inventors have found that these defects can be overcome if the present invention is adopted, and have completed the present invention.

According to research by the present inventors, when using an electrophotographic photoreceptor, if the photoreceptor is always heated to at least 50°C or higher, the same level of photoreceptor characteristics as the initial one will be developed even after repeated use. It was discovered that In this case, the upper limit of the heating temperature is not particularly limited, but heating at a high temperature may cause deterioration such as increase in organic substances in the photosensitive layer, or may cause melting or sticking of toner in the developing area. Although there are some differences depending on the upper limit heating temperature in the present invention and the constituent materials such as the photoreceptor and toner, it is preferably 100° C. or lower, and more preferably 80° C. or lower.

In addition, as a heating means, an electric resistance heater (Unexamined Japanese Patent Publication No. 51
-111338 Publication), a method of blowing warm air (Japanese Patent Application Laid-open No. 51-111338, Japanese Patent Application Laid-Open No. 62-12148)
2), using a sheet heating element as a support (Japanese Unexamined Patent Publication No. 61-7843), and pasting a sheet heating element on the inside of the support, but are not limited to these. Never.

Although the electrophotographic process of the present invention has the above configuration, a cooling means and an actuation means for the cooling means may be used in addition to the above configuration as another configuration. That is, it is useful to employ the cooling means when the photoreceptor is heated above a required temperature or when the heated photoreceptor is cooled to a predetermined temperature during use. In this case, the cooling means is to blow cooling air (Japanese Patent Laid-Open No. 62-1214
82), a method using a refrigerant, etc., but the method is not limited thereto.

The above-mentioned heating means and cooling means may be installed inside the photoreceptor, and/or one or more of them may be installed at appropriate positions outside the photoreceptor at the same time.

Next, the electrophotographic photoreceptor used in the present invention will be explained with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of the structure of a photoreceptor used in the present invention, in which a photoreceptor layer 14 is provided on a conductive support 11. As shown in FIG.

FIGS. 2A and 2S are cross-sectional views showing another example of the structure, in which the photosensitive layer is composed of a stack of a charge generation layer 21 and a charge transport M22.

FIG. 3 shows yet another example of the structure, in which the conductive support 11 and the photosensitive Jt! A subbing layer 15 is provided between the layers 14.

4 shows a structure in which an FF retention layer 12 is provided on the photosensitive layer 14 in FIG. 1, and FIG. 5 shows a structure in which an intermediate M13 is provided between the photosensitive layer 14 and the protective layer 12 in FIG. be.

FIGS. 6a and 6s are respectively the same as FIGS.

FIG. 7 shows the conductive support 11 and the photosensitive layer 14 in FIG.
A subbing layer 15 is provided in between.

The conductive substrate 11 may be one that exhibits conductivity with a volume resistance of 1010Ω1 or less, such as aluminum, nickel,
Metals such as chromium, nichrome, copper, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide are coated on film or cylindrical plastic or paper by vapor deposition or sputtering, or aluminum, Plates of aluminum alloy, nickel, stainless steel, etc. and their materials, 1.1. , after making it into a blank pipe using extrusion, drawing, etc. methods.

A pipe or the like whose surface has been treated by cutting, superfinishing, polishing, etc. can be used.

The photosensitive layer 14 in the present invention can be either inorganic or organic. Examples of the inorganic photosensitive layer include amorphous Ss, 5e-Te compound, 5a-As compound, 5s-
Examples include Te-CD compounds, CdS, ZnO, and the like.

Next, the organic photosensitive layer 14 will be explained, but first, the laminated photosensitive layer will be described.

The charge generation layer 21 is a layer mainly made of a charge generation substance,
A binder resin may be used if necessary.

Binder resins include polyamide, polyurethane,
Polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone,
Polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. are used.

Examples of the charge generating substance include CI Pigment Blue 25 [Color Index (CI) 21180],
CI Pigment Red 41 (CI 21200),
C.I. Acid Red 52 (CI 45100), C.I. Basic Red 3 (CI 45210), and a phthalocyanine pigment having a porphyrin skeleton,
Azo pigments having a carbazole skeleton (JP-A-53-95)
033), an azo pigment having a distyrylbenzene skeleton (described in JP-A-53-133455)
, an azo pigment having a triphenylamine skeleton (Japanese Unexamined Patent Publication No. 5
3-132547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728), an azo pigment having an oxadiazole skeleton (described in JP-A-54-12742), Azo pigments having a fluorenone skeleton (described in JP-A No. 54-22834), azo pigments having a bisstilbene skeleton (described in JP-A-54-17733), azo pigments having a distyryloxadiazole skeleton ( Japanese Patent Publication No. 54-2129
Azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-17734), CI Pigment Blue 16 (CI 7410)
0), C.I. Butt Brown 5 (CI 73410), C.I. Butt Dye (CI
73030), and perylene pigments such as Argo Scarlet B (manufactured by Violet) and Indance Scarlet R (manufactured by Bayer).

Among these charge generating substances, azo pigments are preferred.

These charge generating substances may be used alone or in combination of two or more.

The binder resin is suitably used in an amount of 0 to 100 parts by weight, preferably 0 to 100 parts by weight, based on 100 parts by weight of the charge generating substance.
~50 parts by weight.

The charge generation layer is prepared by dispersing a charge generation substance together with a binder resin if necessary using a ball mill, attritor, sand mill, etc. using a solvent such as tetrahydrofuran, cyclohexane, dioxane, dichloroethane, etc., diluting the dispersion liquid appropriately and applying it. It can be formed by Application can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer 22 can be formed by dissolving or dispersing a charge transport substance and a binder resin in a suitable solvent, coating the solution on the charge generation layer, and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added if necessary.

Charge transport materials include hole transport materials and electron transport materials.

As hole transport substances, poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polyvinylpyrene, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives,
Triphenylamine derivatives, 9-(P-diethylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, benzidine derivatives Electron-donating substances such as

Examples of the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone,
2,4,5.7-titranitroxanthone, 2.4.8
-trinidrothioxanthone, 2,6.8-trinitro-4H-indeno(1,2-b)thiophen-4-one, 1.3.7-trinitrodibenzothiophene-5,
Examples include electron-accepting substances such as 5-dioxide.

These charge transport substances may be used alone or in a mixture of two or more.

Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N- Examples include thermoplastic or thermosetting resins such as vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. are used.

The thickness of the charge transport layer 22 is suitably about 5 to 50 mm.

Next, a case where the photosensitive layer 14 has a single layer structure will be described.

In this case as well, most of the materials are of a functionally separated type consisting of a charge generating substance and a charge transporting substance.

That is, the compounds shown above can be used as the charge generating substance and the charge transporting substance.

A single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance and a binder resin in a suitable solvent, coating the solution and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added if necessary.

As the binder resin, in addition to using the binder resin mentioned above for the charge transport layer 22 as is, the binder resin for the charge generation layer 2
The binder resins listed in 1 may be used in combination.

The single-layer photosensitive layer is formed by dipping coating, spray coating, bead coating, etc. using a coating solution in which a charge generating substance, a charge transporting substance, and a binder resin are dispersed using a dispersion machine using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexanone. Can be formed by coating.

The thickness of the single photosensitive layer is 5 to 50. The degree is appropriate.

In the present invention, it is also possible to further provide an ablation layer on the photosensitive layer 14.

Further, in the present invention, as shown in FIG. 5, by providing an intermediate layer 13 between the conductive support and the photosensitive layer, it is possible to further improve the effects of the present invention, and You can also improve your gender.

The intermediate layer 13 includes S10. Those in which inorganic materials such as AatOa are applied by vapor deposition, sputtering, anodization, etc., polyamide resins (JP-A-58-30757, JP-A-58-98739) and alcohol-soluble nylon resin (JP-A-58-98739). Publication No. 60-196766), water-soluble polyvinyl butyral resin (Japanese Unexamined Patent Publication No. 60-2325)
No. 53), polyvinyl butyral resin (Japanese Unexamined Patent Publication No. 58
106549), a resin layer made of polyvinyl alcohol, etc. can be used.

Furthermore, a resin intermediate layer in which pigment particles such as ZnO, TiO2, ZnS, etc. are dispersed can also be used as the intermediate layer.

Furthermore, as the intermediate layer 13 of the present invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, etc. can also be used.

The appropriate thickness of the intermediate layer 13 is 0 to 5 ps.

The resin used for the protective layer 12 is ABSII!
II fat, ACS resin, olefin vinyl copolymer resin,
Chlorinated polyether, allyl resin, phenolic resin, polyacetal, polyamide, polyamideimide, polyarylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, methacrylic resin, polymethylpentene , polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene resin, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, and the like.

In addition, from the viewpoint of wear resistance, polytetrafluoroethylene resin, fluorine resin, and silicone resin can be added as additives to lower the wear coefficient and improve wear resistance and scratch resistance. The wear resistance can also be improved by dispersing inorganic compounds such as , tin oxide, and potassium titanate into the resin.

The thickness of this surface protective layer is 0.5-10. , preferably 1
~5 ps.

Furthermore, in the present invention, as shown in FIGS. 3 and 7, a subbing layer 15 can be provided between the conductive support 11 and the photosensitive layer 14. In this case, the resin used in the intermediate layer is used as is as the resin forming the undercoat layer.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 On an aluminum cylinder with an outer diameter of 40 m+a and a length of 250 mm, a charge generation layer coating liquid and a charge transport layer coating liquid having the following compositions were applied and dried to form a charge generation layer (0.1 μs) and a charge transport layer ( 20μ,) was formed.

[Charge generation layer coating liquid]

Trisazo pigment with the following structural formula: 2 parts by weight Cyclohexanone 70〃Methyl ethyl ketone 28〃[Charge transport layer coating liquid] Charge transport material with the following structural formula: 10 parts by weight Tetrahydrofuran 80〃The organic photoreceptor prepared as above was printed using a laser printer ( The probe of the surface electrometer was set at a position where the surface potential of the photoreceptor immediately after charging could be measured. In addition, the heater for heating the photoreceptor was a heating element attached to the inside of the aluminum drum, and the drum temperature was controlled to be 25°C (room temperature), 40°C, 45°C, 50°C, 60°C, and 70°C. . After setting each condition, the laser printer was used repeatedly and the surface potential of the unexposed area immediately before development was measured.

FIG. 8 shows the relationship between the surface potential and the photoreceptor temperature after 3,000 sheets were printed (-800 V at the initial stage).

From FIG. 8, it can be seen that even after repeated use, there is little decrease in the surface potential of the non-exposed area in the region of 50° C. or higher, and deterioration of charging characteristics over time is effectively prevented.

Example 2 [Charge generation layer coating liquid] A composition consisting of 10 parts by weight of X-type metal-free phthalocyanine and 185 parts by weight of cyclohexanone was dispersed and mixed in a ball mill for 48 hours to obtain a charge generation layer coating liquid. This coating solution was applied onto a polyester film support having an aluminum conductive layer and dried to form a charge generating layer having a thickness of 0.2 IJm. On top of this, a charge transport layer coating solution with the following composition was applied and dried, and the film thickness was 20 μs.
An electrophotographic photoreceptor was prepared by forming a charge transport layer.

[Charge transport layer coating liquid]

A charge transport material having the following structural formula: 10 parts by weight Tetrahydrofuran: 80 parts by weight Next, this electrophotographic photoreceptor was coated with a conductive layer and bonded with a belt,
Next, we modified it so that it could be equipped with a device that could blow warm air onto it, and used it as a photoreceptor for mounting. It was loaded onto a laser printer (Ricoh LP-4080). This laser printer (10℃, 40%), (25℃
, 45%) and (25° C., 90%), and the 3000th image was evaluated. The temperature of the photoreceptor was maintained at 50°C. The results are shown in Table-1.

Comparative Example 1 Evaluation was conducted in the same manner as in Example 2, except that the photoreceptor temperature was not maintained at 50°C. The results are shown in Table-1.

Table-1 0: No decrease in density or background staining observed.

Δ: No decrease in density is observed, but background staining becomes noticeable.

X: Density decreases significantly, and background stains also become noticeable.

Example 3 [Charge generation layer coating liquid] A composition consisting of 2 parts by weight of polyvinyl butyral resin, 120 parts by weight of cyclohexanone, and 60 parts by weight of cyclohexane was dispersed and mixed in a ball mill for 48 hours to obtain a charge generation layer coating liquid. This was applied as a subbing layer to an aluminum drum having an outer diameter of 80 mm and a length of 340 mm, and approximately 0.1 μl of this was coated on top of the polyamide resin coating (0.3 μff1).

(Coating liquid quoted below) Methanol 96 Jyushabu Further on top of this, apply a coating liquid for the charge transport layer having the following composition.
A photoreceptor was obtained by coating pI11.

[Charge transport layer coating liquid]

Charge transport material having the following structural formula: 10 parts methylene chloride 80 parts by weight or more The photoreceptor prepared as above was set in a copying machine Ricopy FT551O modified to be negatively charged, and heated with hot air as in Example 2. For spraying, the apparatus was set, and the surface potential of the non-exposed area immediately before development was measured in the same manner as in Example 1. Photoreceptor temperature is 5
It was repeatedly used for up to 5,000 copies while maintaining the temperature at 5°C [note that the conditions were room temperature (25°C, 45%)]. The results are shown in Figure 9.

Comparative Example 2 Same as Example 3 except that the photoreceptor temperature was repeatedly used without controlling it.
I gave the exact same evaluation. The results are shown in Figure 9.

Example 4 On an aluminum drum having a diameter of 80 mm and a length of 340 mm, a charge transport layer having the following composition was coated in an amount of 20 μa.

[Charge transport layer coating liquid]

Tetrahydrofuran: 80 parts by weight Monochlorobenzene: 80 parts by weight h3 Approximately two charge generation layers having the following composition were coated thereon.

[Charge generation layer coating liquid]

Polyvinyl butyral resin: 4 parts by weight Cyclohexanone: 120 parts by weight Methyl isobutyl ketone: 60 parts by weight or more
T5510 was set, a hot air blowing device similar to that in Example 2 was installed, and image evaluation was performed under the same environmental conditions as in Example 2 (temperature: 60° C.).

As a result of evaluating image samples after 4000 sheets, Example 4
In the case of , clear images with no blurring or background stains were obtained, but in the case of no application, background stains occurred at low temperatures and blurring at high humidity.

Example 5 On the organic photosensitive layer of the photoreceptor used in Example 1, 4μ of a protective layer coating solution having the following composition was coated.

[Protective layer coating liquid]

Conductive titanium (manufactured by Mitsubishi Metals) 100 parts by weight toluene
240 parts butanol
After mixing 60 parts by weight or more of the liquid and dispersing it in a ball mill for 72 hours, the solid content concentration is 1% so that toluene/butanol = 4/l (heavy electric ratio).
diluted with.

The photoreceptor prepared as described above was placed on a laser printer similar to that in Example 1, and printed under the same conditions as in Example 1. FIG. 1O shows the relationship between the surface potential and the photoreceptor temperature when 3000 sheets were printed (initially -800 V).

As can be seen from Figure 10, even after repeated use,
It can be seen that in the temperature range of 50° C. or higher, the surface potential of the non-exposed area decreases little, and deterioration of the charging characteristics over time is effectively prevented.

Example 6 Example 2 except that about 3p of the protective layer coating solution used in Example 5 was applied on the organic photosensitive layer of the photoreceptor used in Example 2.
An electrophotographic photoreceptor was prepared in the same manner as described above. Next, a printing test similar to that in Example 2 was conducted using this photoreceptor. The results are shown in Table-2.

Comparative Example 3 Evaluation was conducted in the same manner as in Example 6, except that the photoreceptor temperature was not maintained at 50°C. The results are shown in Table-2.

Table-2 *: No image appears.

Example 7 An electrophotographic photoreceptor was prepared in the same manner as in Example 3, except that the same protective layer coating solution as in Example 5 was coated on the photosensitive layer to a thickness of 4 μm. Copying was then carried out using this photoreceptor under the same conditions as in Example 3. The results are shown in FIG.

Comparative Example 4 The same evaluation as in Example 6 was carried out except that the photoreceptor temperature was not controlled and the photoreceptor was used repeatedly. The results are shown in FIG.

Example 8 In Example 4, a 0.3 μm thick intermediate layer having the composition shown below was provided on the charge generation layer, and a 4 μm thick protective layer similar to Example 5 was further coated on this intermediate layer.

[Intermediate layer coating liquid]

Tetrahydrofuran: 40 parts by weight Cyclohexanone: 50 parts by weight A photoreceptor prepared by Sushiray coating was set in a copying machine, Ricopy FT5510, and hot air blowing similar to that in Example 2 was carried out by mounting the apparatus on the tower. Under the same environmental conditions as Example 2,
Image evaluation was performed (photoreceptor temperature was 60° C.).

As a result of evaluating the image sample when 4ooo saddled, Example 8
A clear image with no blur or background stains was obtained, but
When not applied, background staining occurred at low temperatures and humidity, and blurring occurred at high humidity.

〔effect〕

Since the method of the present invention has the above-mentioned configuration, it has the following remarkable effects.

(1) Image blurring and image distortion caused by high temperature and humidity, which are particularly problematic when a protective layer is provided, can be prevented.

(2) It is possible to prevent the storage of the photoreceptor at low temperatures and the background smearing of images at low temperatures and humidity.

(3) In organic photoreceptors, deterioration of charging characteristics after repeated use of the photoreceptor can be prevented.

That is, it is possible to obtain a good image without background stains during image density reduction, image density unevenness, fog, or reverse development in copying machines, printers, etc.

[Brief explanation of the drawing]

Figures 1, 2a, 2s, 3, 4, 5, 6a, 6s and 7 are schematic diagrams of the electrophotographic photoreceptor used in the present invention. FIG. Figures 8 and 10 are graphs showing the relationship between photoreceptor temperature and surface potential in the electrophotographic process, and Figures 9 and 11 are graphs showing the correlation between photoreceptor temperature, surface potential, and number of copies in the electrophotography process. This is a graph representing 11... Conductive support 12... Protective layer 13... Intermediate layer 14... Photosensitive layer 15... 1 undercoat 21... Charge generation layer 22... Charge transport layer Patent application People Rico Co., Ltd. - Figure 1 Figure 2 (0) Figure 2 (b) Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 Photoconductor 5 & friend ('C) Figure 9 Copy & number (sheets) Figure 1O/@hole #-Yuyan ('C) Number of copies of Figure 1I (travel)

Claims (3)

[Claims] (1) In an electrophotographic process that includes a step of charging and exposing an electrophotographic photoreceptor comprising at least a photosensitive layer on a conductive support to form an electrostatic latent image, the photoreceptor is always
An electrophotographic process characterized by being held at temperatures above ℃. (2) The electrophotographic process according to claim 1, wherein the electrophotographic photoreceptor has a protective layer provided on the photosensitive layer. (3) The electrophotographic process according to claim 1 or 2, wherein the photosensitive layer is formed from a charge generating material and a charge transporting material.