JP2023042423A - Electro-photographic device - Google Patents

Abstract

To provide an electro-photographic device which improves the uniformity of electrification potentials and creates a high-quality image when a thick-film electro-photographic photoreceptor is used for a DC contact electrification method.SOLUTION: An electro-photographic device comprises: an electro-photographic photoreceptor which has a cylindrical support body, a charge generating layer and a charge transfer layer in this order, the charge transfer layer being a surface layer; an electrification roller for electrifying the electro-photographic photoreceptor; and a power source which applies only the DC voltage to the electrification roller. The average film thickness of the charge transfer layer in a portion where the electrification roller is in contact with the charge transfer layer is equal to or greater than 30 μm, projections which are continuously formed in the peripheral direction of the electro-photographic photoreceptor, has the height being between 0.1 μm-0.2 μm and the inclination being between 0.007 μm/mm-0.020 μm/mm exist on the surface of the charge transfer layer, the plurality of protrusions exist in a portion in the axial direction of the electro-photographic photoreceptor which the electrification roller contacts, and when the width between the adjacent apexes of the protrusions is L, L is between 10 mm to 60 mm.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrophotographic apparatus using an electrophotographic photoreceptor.

In an electrophotographic apparatus, image formation is generally performed by the following processes. Charging process for charging an electrophotographic photosensitive member as an image carrier, exposure process for forming an electrostatic latent image by exposure means such as laser scanning exposure on the electrophotographic photosensitive member, and visualization of the electrostatic latent image with toner. developing process. A transfer process for transferring the toner image on the electrophotographic photosensitive member to the recording medium, a fixing process for fixing the toner image on the recording medium, and a cleaning process for cleaning the electrophotographic photosensitive member after the transfer process.

In the case of forming an image by such a series of flows, external additives, which are various fine particles, are adhered to the surfaces of the toner particles for the purpose of imparting appropriate powder properties to the toner. Also, the external additive generally has the same chargeability as the toner.

Further, the charging device for charging the electrophotographic photosensitive member is roughly classified into a non-contact type and a contact type.
Non-contact charging devices generally use corona chargers. That is, the corona charger is arranged opposite to the photoreceptor without being in contact with the photoreceptor. A high voltage (5 to 8 kV DC) is applied to the metal wire (discharge wire) of the corona charger. The corona discharge generated at this time charges the surface of the electrophotographic photosensitive member.
In the contact-type charging device, a charging member such as a charging roller (hereinafter referred to as "charging roller") is brought into contact with the electrophotographic photosensitive member, and a voltage is applied to the charging roller to thereby charge the surface of the electrophotographic photosensitive member. is charged. A contact type charging device has advantages such as low ozone and low power consumption as compared with a non-contact type charging device.

The contact type charging device includes a so-called DC contact charging method in which only a DC voltage is applied to the charging roller to charge the electrophotographic photosensitive member, and a DC voltage superimposed with an AC voltage is applied to the charging roller. There is a so-called AC contact charging system in which an electrophotographic photosensitive member is charged as a contact charging method.
Compared with the AC contact charging method, the DC contact charging method has advantages such as no charging sound, no electrostatic noise, cost reduction of the power source, low ozone, and low cost. In addition, excellent merits such as a small amount of electric current associated with discharging for charging the surface of the electrophotographic photosensitive member to a predetermined potential can be obtained.
On the other hand, in the DC contact charging method, there is a problem that the charging potential of the charged surface of the electrophotographic photosensitive member tends to be non-uniform. The nonuniformity of the charging potential on the electrophotographic photosensitive member before exposure is important because it greatly affects the quality of the electrostatic latent image formed in the subsequent exposure process. For example, uneven charging potential generated on the electrophotographic photosensitive member before exposure causes uneven image density and reduced reproducibility of image details. Non-uniformity of charging potential is a significant problem in terms of image quality.

In order to solve such problems, various electrophotographic apparatuses have been proposed.
For example, Japanese Patent Application Laid-Open No. 2002-100000 discloses a method for suppressing contamination of a charging member by establishing a predetermined relationship between the work functions of a charging member, a contact member that contacts the charging member, and an external additive added to the toner. , discloses a technique for suppressing charging failure.
Further, in Patent Document 2, by setting the film thickness and the capacitance of the charge transport layer of the electrophotographic photosensitive member within a predetermined range, streaks (perpendicular to the direction of movement of the surface to be charged) due to non-uniform charging can be prevented. Techniques for suppressing the occurrence of directional stripes have been disclosed.

JP 2006-268021 A Japanese Patent Application Laid-Open No. 2005-141031

Conventionally, the uniformity of charging potential has been improved by the measures described above, and the image quality of the obtained image has been improved. However, in recent years, there is an increasing demand from the market for cost reduction of electrophotographic apparatuses and running cost reduction when using electrophotographic apparatuses. There is a growing demand for a longer lifespan of the body.

In response to these demands, utilizing the advantages of the DC contact charging method as described above is effective in reducing the cost of the electrophotographic apparatus. Further, it is known that increasing the film thickness of the electrophotographic photoreceptor is very effective for prolonging the life of the electrophotographic photoreceptor. For example, when a charge generation layer and a charge transport layer are laminated in this order as a photosensitive layer on a support and the charge transport layer also serves as a surface layer, the thickness of the charge transport layer is increased to obtain an electrophotographic photoreceptor. It is possible to greatly extend the life of

However, when a thick-film electrophotographic photoreceptor is used in the DC contact charging method, non-uniformity in charging potential may become apparent at the initial stage of use of the electrophotographic apparatus.
With respect to such a problem, it can be said that there is still a need for improvement in the prior art in terms of improving the uniformity of charging potential.

For example, in Japanese Unexamined Patent Application Publication No. 2002-100000, charging uniformity is improved by suppressing contamination of the charging member by an external additive. Therefore, when the electrophotographic apparatus is used to some extent and the external additive is supplied to the surface of the electrophotographic photosensitive member and the contact portion of the cleaning blade and the electrophotographic photosensitive member to some extent, the function of uniformity of charging potential can be obtained. . On the other hand, since the presence of the external additive is slight at the beginning of use of the electrophotographic apparatus, it may not be possible to sufficiently improve the uniformity of charging potential at the beginning of use.

Further, as in Patent Document 2, streaks (streaks in the direction perpendicular to the moving direction of the charged surface) can be prevented by setting the film thickness and the capacitance of the charge transport layer of the electrophotographic photosensitive member within a predetermined range. ) can be suppressed. However, when a thick-film electrophotographic photosensitive member is used, discharge becomes uneven in the initial period of use of the electrophotographic apparatus, and sufficient functions cannot be obtained for images with a rough texture in the halftone area. Sometimes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is capable of improving the uniformity of charging potential when a thick-film electrophotographic photosensitive member is used in a DC contact charging system, thereby producing an image of higher quality than before. An object of the present invention is to provide an electrophotographic apparatus that provides

In order to achieve the above object, an electrophotographic apparatus according to the present invention comprises:
having a cylindrical support, a charge generation layer and a charge transport layer in this order,
an electrophotographic photoreceptor in which the charge transport layer is a surface layer;
a charging roller for charging the electrophotographic photosensitive member;
and a power supply that applies only a DC voltage to the charging roller,
The charge transport layer has an average thickness of 30 μm or more at a portion where the charging roller contacts the charge transport layer, and the charge transport layer is continuously formed on the surface of the charge transport layer in the circumferential direction of the electrophotographic photosensitive member. There is a convex portion with a height of 0.1 μm or more and 0.2 μm or less and an inclination of 0.007 μm/mm or more and 0.020 μm/mm or less,
a plurality of the convex portions are present in a portion in the axial direction of the electrophotographic photosensitive member with which the charging roller abuts;
It is characterized in that L is 10 mm or more and 60 mm or less, where L is the width between adjacent vertices of the convex portion.

According to the present invention, it is possible to improve the uniformity of the charging potential at the initial stage of use of the electrophotographic apparatus, and to provide an electrophotographic apparatus that provides higher quality images than conventional ones.

1 is a schematic configuration diagram showing an example of the configuration of an electrophotographic photoreceptor of the present invention; FIG. 3 is a graph showing a part of the axial film thickness distribution of the charge transport layer of the electrophotographic photoreceptor of the present invention, and a graph showing the axial distribution of the difference between adjacent film thicknesses in the axial direction. 1 is a schematic diagram showing an example of an electrophotographic apparatus of the present invention; FIG.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
(Electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention is characterized by having a cylindrical support, a charge generation layer and a charge transport layer in this order, the charge transport layer being a surface layer.

(support)
The support is preferably one exhibiting conductivity (conductive support). Examples of materials for the support include metals (alloys) such as iron, copper, gold, silver, aluminum, zinc, titanium, lead, nickel, tin, antimony, indium, chromium, aluminum alloys, and stainless steel. A metal support or a plastic support having a film formed by vacuum deposition using aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like can also be used. A support obtained by impregnating plastic or paper with conductive particles such as carbon black, tin oxide particles, titanium oxide particles, or silver particles, or a support made of a conductive binder resin can also be used.
The surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, or the like for the purpose of suppressing interference fringes due to scattering of laser light.
A conductive layer may be provided between the support and the undercoat layer or charge generation layer described below for the purpose of suppressing interference fringes due to scattering of laser light and covering scratches on the support.

(Conductive layer)
The conductive layer is formed by coating a support with a conductive layer coating solution obtained by dispersing carbon black, a conductive pigment, a resistance control pigment, etc. together with a binder resin to form a coating film. It can be formed by drying the membrane. In addition, a compound that is cured and polymerized by heating, ultraviolet irradiation, radiation irradiation, or the like may be added to the conductive layer coating liquid. A conductive layer formed by dispersing a conductive pigment or a resistance control pigment tends to have a roughened surface.
Examples of the binder resin used for the conductive layer include polymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol, and polyvinyl acetal. , polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin, and the like.
Examples of conductive pigments and resistance-adjusting pigments include metal (alloy) particles such as aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, and plastic particles in which these are vapor-deposited on the surface. . Particles of metal oxides such as zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, and antimony- or tantalum-doped tin oxide can also be used. can. These may be used alone or in combination of two or more. When two or more of them are used in combination, they may be simply mixed, or may be in the form of solid solution or fusion.
The film thickness of the conductive layer is preferably 0.2 μm or more and 40 μm or less, more preferably 1 μm or more and 35 μm or less, and more preferably 5 μm or more and 30 μm or less.

(undercoat layer (intermediate layer))
Between the support or the conductive layer and the photosensitive layer (charge generation layer, charge transport layer), there are the following: improvement of adhesiveness of the photosensitive layer, improvement of coatability, improvement of charge injection from the support, electrical destruction of the photosensitive layer An undercoat layer (intermediate layer) having a barrier function and an adhesive function may be provided for the purpose of protection against damage.
The undercoat layer is formed by applying an undercoat layer coating solution obtained by dissolving a resin (binder resin) in a solvent onto a support or a conductive layer, and drying the resulting coating film. can be done.
Resins used for the undercoat layer include, for example, polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6-nylon, and copolymerized nylon. , glue, gelatin, polyurethane resin, acrylic resin, allyl resin, alkyd resin, phenol resin, epoxy resin, and the like.
The undercoat layer may contain metal oxide particles. Metal oxide particles used in the undercoat layer include, for example, titanium oxide, zinc oxide, tin oxide, zirconium oxide, and aluminum oxide.
The metal oxide particles may be particles whose surfaces are treated with a surface treatment agent such as a silane coupling agent.
Examples of the method for dispersing the metal oxide particles in the coating liquid for the undercoat layer include a method using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, and a liquid collision type high-speed disperser. .
The undercoat layer may further contain organic resin particles or a leveling agent, for example, for the purpose of adjusting the surface roughness of the undercoat layer or reducing cracks in the undercoat layer. As the organic resin particles, hydrophobic organic resin particles such as silicone particles and hydrophilic organic resin particles such as crosslinked polymethacrylate resin (PMMA) particles can be used.
The film thickness of the undercoat layer is preferably 0.05 μm or more and 40 μm or less, more preferably 0.2 μm or more and 35 μm or less.

(Charge generating layer)
Examples of charge-generating substances used in the charge-generating layer include pyrylium and thiapyrylium dyes, phthalocyanine pigments having various central metals and various crystal forms (α, β, γ, ε, X types, etc.), and anthanthrones. Examples include pigments, dibenzpyrenequinone pigments, pyranthrone pigments, azo pigments such as monoazo, disazo, and trisazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, and quinocyanine pigments. These charge-generating substances may be used alone or in combination of two or more.
The charge-generating layer is formed by applying a charge-generating layer coating liquid obtained by dispersing a charge-generating substance together with a binder resin and a solvent onto a support, a conductive layer, or an undercoat layer to form a coating film, It can be formed by drying the obtained coating film. Also, the charge generation layer may be a deposited film of a charge generation substance.
The mass ratio of the charge-generating substance and the binder resin is preferably in the range of 1:0.3 or more and 1:4 or less.
Dispersion treatment methods include, for example, methods using homogenizers, ultrasonic dispersion, ball mills, vibrating ball mills, sand mills, attritors, roll mills, and the like.
Examples of the binder resin used in the charge generation layer include polymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol, polyvinyl alcohol, and the like. Acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicone resin, epoxy resin, and the like.
The thickness of the charge generating layer is preferably 5 μm or less, more preferably 0.1 μm or more and 2 μm or less.

(Charge transport layer)
Examples of charge-transporting substances used in the charge-transporting layer include pyrene compounds, N-alkylcarbazole compounds, hydrazone compounds, N,N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, Examples include styryl compounds and stilbene compounds. These charge transport substances may be used alone or in combination of two or more.
The charge transport layer is formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent onto the charge generation layer to form a coating film, and drying the resulting coating film. can be formed by Further, when a charge transporting substance having film-forming properties is used alone, the charge transporting layer can be formed without using a binder resin.
Examples of the binder resin used in the charge transport layer include polymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol, polyvinyl alcohol, and the like. Acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicone resin, epoxy resin, and the like.

The film thickness of the charge transport layer, which is a feature of the present invention, will be described in detail with reference to FIGS. 1A to 1D and 2A to 2B.

FIG. 1 is a schematic configuration diagram for explaining the electrophotographic photoreceptor of the present invention.
FIG. 1A shows a schematic cross-sectional view of an electrophotographic photoreceptor of the present invention and a charging roller for charging the electrophotographic photoreceptor. Here, the electrophotographic photosensitive member 100 is configured by providing, for example, an undercoat layer 102 , a charge generation layer 103 and a charge transport layer 104 on a cylindrical support 101 . A charging roller 110 has an overall length of S (mm). The total length S (mm) of the charging roller means the axial length of the contact surfaces of the electrophotographic photosensitive member 100 and the charging roller 110 .
(B) to (D) of FIG. 1 are schematic graphs showing the axial distribution of the film thickness of the charge transport layer 104 of the electrophotographic photoreceptor 100 of the present invention. The horizontal axis indicates the axial position of the electrophotographic photoreceptor 100 and the vertical axis indicates the film thickness of the charge transport layer 104 .
Broken lines in (A) to (D) of FIG. 1 indicate lines dividing the total length S of the charging roller 110 into five equal parts.
Projections 120a to 120t in FIGS. 1B to 1D are projections provided on the surface of the charge transport layer 104 and continuously formed in the circumferential direction of the electrophotographic photosensitive member 100. FIG. For example, the convex portion 120d in FIG. 1B is provided at the center in the axial direction of the electrophotographic photosensitive member 100 and is formed continuously around the circumference.

FIG. 1B is an example showing the positions of the projections 120a to 120g in the axial direction of the electrophotographic photosensitive member 100. FIG. The projections 120a to 120g are continuously provided from the center of the electrophotographic photosensitive member 100 toward both ends. As a result, a region A in which the projections 120a to 120g are continuously provided is formed in the vicinity of the center of the electrophotographic photosensitive member 100. As shown in FIG.

In (C) of FIG. 1, a region B is formed as a region Bc in which convex portions 120j and 120k are continuously provided near the center of the electrophotographic photosensitive member. A region B as a region Be in which the convex portions 120h and 120i are continuously provided on both sides of the region Bc, and a region Be other than the region Bc in which the convex portions 120l and 120m are continuously provided. A region B as is provided. There is a constant gap between the region Bc and the regions Be on both sides, and the region Bc and the region Be are provided near the center of the electrophotographic photosensitive member 100 .

In FIG. 1D, projections 120n to 120t are discretely formed over the entire axial direction of the electrophotographic photoreceptor 100 in the axial direction.

According to the present invention, it is possible to improve the uniformity of charging potential at the initial stage of use of an electrophotographic apparatus. The reason for this is considered by the inventors as follows.
In the early stage of use of the electrophotographic photoreceptor, the external additive adhering to the surface of the toner particles adheres to the charging roller 110 and contaminates the charging roller 110, so that the effect of making the charging potential non-uniform is considered to be negligible. be done.
Therefore, it is considered that the non-uniformity of charging in the initial stage of use is largely affected by changes in the contact state between the contact surfaces of the charging roller 110 and the electrophotographic photosensitive member 100 .

In the contact charging method, in which the electrophotographic photosensitive member 100 is charged by bringing the charging roller 110 into contact with the electrophotographic photosensitive member 100, in a minute space in the vicinity of the contact portion between the electrophotographic photosensitive member 100 and the charging roller 110, void destruction discharge according to Paschen's law is performed. done. Generally, in an electrophotographic apparatus, the electrophotographic photosensitive member 100 is charged while being rotated or moved with respect to the charging roller 110 .

That is, with the contact position between the electrophotographic photosensitive member 100 and the charging roller 110 as a boundary, the area is divided into an upstream side and a downstream side, and charging is performed in both the upstream and downstream small spaces. At this time, void destruction discharge occurs in accordance with Paschen's law, and due to the characteristics of such a charging mechanism, it is important to stably form both minute spaces for uniform charging.

Although not regarded as a problem in the past, when the thickness of the charge transport layer 104 is increased to, for example, 30 μm in order to increase the durability of the electrophotographic photoreceptor 100, the charging potential in the initial period of use of the electrophotographic apparatus increases. Non-uniformity may become apparent. The reason for this is considered as follows. By increasing the thickness of the charge transport layer, the electrostatic capacity of the electrophotographic photoreceptor 100 is reduced. As a result, even if the charge supplied to the surface of the electrophotographic photosensitive member 100 changes by the same amount as in the conventional case, the change in the surface potential of the electrophotographic photosensitive member 100 increases in proportion to the film thickness ratio. .

In order to stabilize the formation of both microspaces, for example, the electrophotographic photosensitive member 100 has flanges attached to both ends thereof, and the flanges are attached to positioned bearings. Both ends of the charging roller 110 are vertically pressed against the electrophotographic photosensitive member 100 with a predetermined pressing force via elastic means. As described above, it is considered that the positional relationship between the electrophotographic photosensitive member 100 and the charging roller 110 is relatively stable in the direction perpendicular to the axial direction of the electrophotographic photosensitive member 100 .

On the other hand, with respect to the axial direction of the electrophotographic photosensitive member 100, applying some kind of force or providing a mechanical mechanism to both the electrophotographic photosensitive member 100 and the charging roller 110 would cause inconvenience during installation and increase costs. It is generally not done because it invites

According to the present invention, on the surface of the charge transport layer 104 at the portion where the charging roller 110 abuts, there is a projection of a predetermined shape continuously formed in the circumferential direction of the electrophotographic photosensitive member. There are multiple parts. Therefore, the convex portion has a so-called wedge-like effect, which makes it possible to suppress the axial movement of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 . As a result, it is considered that both the minute spaces are stably formed. Further, since the convex portions are formed continuously in the circumferential direction of the electrophotographic photosensitive member 100, even when the electrophotographic photosensitive member 100 is charged while rotating or moving with respect to the charging roller 110, both small and small portions are constantly formed. It is considered that the space is stably formed.

Furthermore, according to the present invention, by providing a plurality of protrusions having a predetermined shape, the electrophotographic photosensitive member 100 and the charging roller 110 can be separated from each other when, for example, the entire surface of the electrophotographic photosensitive member 100 is provided with a fine shape. No decrease in contact area with Therefore, it is considered that this is more effective in suppressing the movement of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 in the axial direction.

In the present invention, the height of the projections continuously formed on the surface of the charge transport layer 104 in the circumferential direction of the electrophotographic photosensitive member 100 is preferably 0.1 μm or more and 0.2 μm or less. If the height of the protrusions is less than 0.1 μm, it is not sufficient to suppress the axial movement of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 . If the height of the protrusions is greater than 0.2 μm, the protrusions may appear streak-like in a halftone image.

In the present invention, the inclination of the convex portion is preferably 0.007 μm/mm or more and 0.020 μm/mm or less.
If the inclination of the convex portion is less than 0.007 μm/mm, the axial movement of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 is not sufficiently suppressed. If the inclination of the convex portion is greater than 0.020 μm/mm, the convex portion may appear streak-like in a halftone image. Furthermore, when the inclination of the convex portion is 0.015 μm/mm or less, the convex portion is less likely to appear as streaks in the halftone image. 0.015 μm/mm or less is more preferable.

In the present invention, when the width between adjacent vertices of the convex portion is L (mm), L is preferably 10 mm or more and 60 mm or less. If L is less than 10 mm, it becomes difficult to form a convex portion that satisfies the above height and inclination. If l is larger than 60 mm, the axial movement of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 is not sufficiently suppressed.

Here, the height and inclination of the convex portion and the width L between adjacent vertices of the convex portion will be described with reference to FIG. 2 .
FIG. 2A is a graph showing a partial distribution of the film thickness of the charge transport layer 104 of the electrophotographic photoreceptor 100 of the present invention in the axial direction. The horizontal axis indicates the axial position of the electrophotographic photoreceptor 100 and the vertical axis indicates the film thickness of the charge transport layer 104 . In the drawing, convex portion 1, convex portion 2, and convex portion 3 are three convex portions continuously formed on the surface of the charge transport layer 104 in the circumferential direction of the electrophotographic photosensitive member 100. FIG.
FIG. 2B is a graph showing the difference between adjacent film thicknesses in the axial direction distribution of the film thickness of the charge transport layer 104 of FIG. 2A. The difference at the axial position is the value obtained by subtracting the thickness of the charge transport layer 104 at the axial position to the left from the thickness of the charge transport layer 104 at that axial position. The horizontal axis indicates the position in the axial direction of the electrophotographic photosensitive member 100, and the vertical axis indicates the difference.

In FIG. 2A, the film thickness is obtained by first measuring the film thickness at predetermined intervals (for example, intervals of 1.0 mm) along the circumferential direction at predetermined positions in the axial direction. Then, the average value of the obtained values is taken as the film thickness at a predetermined axial position. Similarly, by measuring the film thickness at predetermined intervals in the axial direction, the axial distribution of the film thickness of the charge transport layer 104 shown in FIG. 2A can be obtained.

There is no particular limitation on how to obtain the film thickness of the charge transport layer 104, and an eddy current method or an optical interference method can be used. In the case of the eddy current method, the film thickness of all layers of the electrophotographic photoreceptor 100 is measured. Measure the film thickness. After that, the film thickness of the electrophotographic photosensitive member 100 formed up to the charge transport layer 104 is measured, and the difference can be calculated.

Also, the optical interference method can be obtained by calculating the difference in the same manner as the eddy current method. Furthermore, when the thickness of each layer differs to some extent, it may be possible to detect only the charge transport layer 104 from the electrophotographic photoreceptor 100 formed up to the charge transport layer 104 .

Next, the height and inclination of each convex portion and the width L between adjacent vertices are obtained.
First, the difference between adjacent film thicknesses is calculated with respect to the obtained film thickness at each axial position. For example, the film thicknesses at adjacent axial positions a1 and a2 shown in FIG. 2A are t1 and t2, respectively. Therefore, the difference in film thickness between these two points (film thickness on the right side - film thickness on the left side in the drawing) is t2-t1=s2. Therefore, the difference of the axis position a2 is assumed to be s2. Similarly, by calculating and plotting the difference over the entire area in the axial direction, a graph showing the difference in film thickness between adjacent measurement points shown in FIG. 2B is obtained.

Next, in FIG. 2B, when the difference values are observed from the left side to the right side in the drawing, the bottom point 1, the top point 1, and the bottom point 2 are defined as follows.

Bottom point 1: Determines the axis position showing the difference of 0 or (-) when the difference changes from 0 or (-) to (+).
For example, in FIG. 2B, the axis positions are a1, a3, and a4. The film thicknesses at that time are the film thickness t1, the film thickness t3, and the film thickness t4, respectively. Therefore, in FIG. 2A, if the X axis is the axial position and the Y axis is the film thickness, the coordinates of each bottom point 1 are (a1, t1), (a3, t3), (a4, t4). becomes.

Vertex 1: After bottom point 1 (when looking at the difference from left to right), when the difference changes from 0 or (+) to (-), the difference is 0 or (+) Defines the axis position to indicate the value.
For example, in FIG. 2B, the axis positions are a5, a6, and a7. The film thicknesses at that time are the film thickness t5, the film thickness t6, and the film thickness t7, respectively. Therefore, in FIG. 2A, when the X axis is the axial position and the Y axis is the film thickness, the coordinates of each vertex 1 are (a5, t5), (a6, t6), and (a7, t7). .

Bottom point 2: After vertex 1 (when looking at the difference from the left to the right), when the difference changes from the (-) value to 0 or (+), the difference is the (-) value. Define the axis position shown.
For example, in FIG. 2B, the axis positions are a8, a4, and a9. The film thicknesses at that time are the film thickness t8, the film thickness t4, and the film thickness t9, respectively. Therefore, in FIG. 2A, if the X-axis is the axial position and the Y-axis is the film thickness, the coordinates of each bottom point 2 are (a8, t8), (a4, t4), and (a9, t9). Become.

By defining the coordinates of each point as described above, for example, for convex portion 1, bottom point 1 is (a1, t1), vertex 1 is (a5, t5), and bottom point 2 is (a8, t8).
Then, the height, inclination, and width L between adjacent vertices are defined and calculated as follows.
Height of convex portion: Average of film thickness difference between bottom point 1 and vertex 1 and film thickness difference between bottom point 2 and vertex 1.
Slope of convex portion: Average of slopes of base point 1 and vertex 1 and slopes of base point 2 and vertex 1.
Width L between adjacent vertices: distance between adjacent vertices 1;

Specifically, in the case of convex portion 1,
Height of convex portion 1=(|t1-t5|+|t5-t8|)/2
Inclination of the convex portion = ((|t1-t5|/|a1-a5|) + (|t5-t8|/|a5-a8|))/2,
The width L between the vertices of adjacent protrusions 1 and 2 is given as |a5-a6|.

There is no particular limitation on the position of the convex portion in the axial direction of the present invention. One continuous region may be provided, or a plurality of continuous regions may be provided at predetermined intervals. Alternatively, they may be provided discretely at predetermined intervals. However, as described above, since the charging roller 110 is structured to press against the electrophotographic photosensitive member 100 at both ends, the pressing pressure is weaker at the center than at the ends. Therefore, in order to stabilize the formation of both the small spaces, it is preferable to concentrate the convex portions near the center in the axial direction on the contact surface between the charging roller 110 and the electrophotographic photosensitive member 100 .

The vicinity of the center shown here means that when the axial length of the contact surface between the electrophotographic photosensitive member 100 and the charging roller 110 is S (mm) as shown in FIG. Divide equally. At that time, the central area divided into 5 equal parts and the area on both sides are combined.
Then, as shown in the region A of FIG. 1B, when the convex portion is continuously provided near the center, the region A should be 2/5 or more of S. is more preferable for the stabilization of
Further, as shown in (C) of FIG. 1, a region Bc and a region Be, which are regions B in which convex portions are continuously provided, are provided in regions of ⅕ or less of S, respectively, and the electrophotographic photosensitive member 100 A region Bc is provided in the center of the region Bc, and regions Be are provided adjacent to the region Bc at predetermined equal intervals in both end directions. Further, it is more preferable to provide the region Bc and the region Be in the vicinity of the center for stabilizing the formation of both the minute spaces.

As a method for producing the electrophotographic photoreceptor of the present invention, there is a method of preparing the coating liquid for each layer as described above, coating the layers in the desired order, and drying the layers. At this time, the method of applying the coating liquid includes dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, and the like. Among these, dip coating is preferable from the viewpoint of efficiency and productivity.

Formation of the convex portions of the present invention is not particularly limited, but it is possible to form convex portions by controlling coating conditions in any manufacturing method.
In the case of dip coating, the electrophotographic photoreceptor 100 formed up to the charge generation layer 103 is immersed in the charge transport layer coating liquid, and then the electrophotographic photoreceptor 100 is pulled up, by controlling the lifting speed. A convex portion may be formed. Alternatively, the projections may be formed by controlling the amount of circulating liquid supplied from a circulating device that supplies the coating liquid.

Additives can be added to each layer of the electrophotographic photoreceptor. Examples of additives include deterioration inhibitors such as antioxidants and ultraviolet absorbers, organic resin particles such as fluorine atom-containing resin particles and acrylic resin particles, and inorganic particles such as silica, titanium oxide, and alumina. be done.

<Structure of Process Cartridge and Electrophotographic Apparatus>
FIG. 3 shows an example of an electrophotographic apparatus equipped with a process cartridge having the electrophotographic photoreceptor 100 of the present invention.
In FIG. 3, a cylindrical electrophotographic photosensitive member 100 of the present invention is rotationally driven about a shaft 302 in the direction of an arrow at a predetermined peripheral speed (process speed). During the rotation process, the surface of the electrophotographic photosensitive member 100 is applied with a predetermined positive or negative potential by a charging means 303 (primary charging means: charging roller, etc.) connected to a power source (not shown) that applies only a DC voltage. charged to Next, the surface of the charged electrophotographic photosensitive member 100 receives exposure light (image exposure light) 311 emitted from exposure means (image exposure means) (not shown). In this manner, an electrostatic latent image corresponding to desired image information is formed on the surface of the electrophotographic photosensitive member 100 .

The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 100 is then developed (regular development or reversal development) with toner (amorphous toner or spherical toner) in developing means 304 to form a toner image. A toner image formed on the surface of the electrophotographic photosensitive member 100 is transferred onto a transfer material 307 by a transfer bias from transfer means (for example, a transfer roller) 306 . At this time, the transfer material 307 is taken out from transfer material supply means (not shown) in synchronism with the rotation of the electrophotographic photosensitive member 100, and is placed between the electrophotographic photosensitive member 100 and the transfer means 306 (contact portion). be fed. A bias voltage having a polarity opposite to that of the charge held by the toner is applied to the transfer means 306 from a bias power source (not shown).

The transfer material 307 to which the toner image has been transferred is separated from the surface of the electrophotographic photosensitive member 100 and conveyed to fixing means 310 to undergo fixing processing of the toner image, whereby an image formed product (print, copy) is electrophotographic. Printed out outside the device.

After the transfer of the toner image, the surface of the electrophotographic photoreceptor 100 is cleaned by cleaning means 308 having a cleaning blade arranged in contact with the surface of the electrophotographic photoreceptor 100 to remove deposits such as residual toner. surface is cleaned. Further, the cleaned surface of the electrophotographic photosensitive member 100 is subjected to static elimination by pre-exposure light 312 from pre-exposure means (not shown), and then repeatedly used for image formation. As shown in FIG. 3, when the charging means 303 is a contact charging means using a charging roller or the like, the pre-exposure means is not necessarily required.

A process cartridge according to the present invention integrally supports an electrophotographic photosensitive member 100 and a cleaning means 308 having a cleaning blade (cleaning member) arranged in contact with the electrophotographic photosensitive member 100, and is detachably attached to an electrophotographic apparatus main body. Cartridge.

In the present invention, the electrophotographic photosensitive member 100, the cleaning means 308, and one or more components selected from the components selected from the charging means 303 and the developing means 304 are housed in a container and integrated as a process cartridge. It is good also as a structure supported by. This process cartridge can be detachably attached to the body of an electrophotographic apparatus such as a copier or a laser beam printer. In FIG. 3, the electrophotographic photosensitive member 100, the charging means 303, the developing means 304 and the cleaning means 308 are integrally supported to form a cartridge, and the electrophotographic apparatus is mounted using a guide means 305 such as a rail of the main body of the electrophotographic apparatus. A process cartridge 301 is detachably attached to the main body.

When the electrophotographic apparatus is a copier or a printer, the exposure light 311 is reflected light or transmitted light from a document, or a sensor reads the document, converts it into a signal, scans a laser beam according to the signal, scans an LED array, or the like. This is the light emitted by driving the liquid crystal shutter array or the like.

The present invention will be described in more detail below with specific examples. However, the present invention is not limited to these. In addition, "part" in an Example means "mass part."

[Example 1]
<Preparation of Electrophotographic Photoreceptor (Photoreceptor-1)>
A cylindrical aluminum cylindrical support having a length of 357.5 mm and an outer diameter of 30 mm was used as the cylindrical support.

Then the following ingredients:
Powder consisting of barium sulfate particles having a coating layer of tin oxide (trade name: Pastran PC1, manufactured by Mitsui Mining & Smelting Co., Ltd.) 60 parts Titanium oxide (trade name: TITANIX JR, manufactured by Tayca Co., Ltd.) 15 parts Resole type Phenol resin (trade name: Phenolite J-325, manufactured by DIC Corporation, solid content 70%) 43 parts of 2-methoxy-1-propanol 50 parts of methanol 50 parts of a solution was put in a sand mill using glass beads with a diameter of 1 mm. for 3 hours to prepare a dispersion.
The following ingredients are added to this dispersion:
Silicone resin (trade name: Tospearl 120, manufactured by Momentive Performance Materials Japan LLC) 3.6 parts Silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.) 0.015 parts The mixture was stirred to obtain a conductive layer coating liquid.
This conductive layer coating liquid was applied onto a cylindrical support by a dip coating method. The coated area was from a position 2 mm measured from the end of the cylindrical support on the top side of the coating to the end of the cylindrical support on the bottom side of the coating. Next, a conductive layer having a thickness of 30 μm was formed by heat curing in an oven at 140° C. for 1 hour.

Then the following ingredients:
Copolymerized nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) 10 parts Methoxymethylated nylon 6 resin (trade name: Toresin EF-30T, manufactured by Teikoku Chemical Co., Ltd.) 30 parts methanol 400 parts / n- It was dissolved in a mixed solvent containing 200 parts of butanol to obtain an intermediate layer coating liquid.
This intermediate layer coating solution was applied onto the conductive layer by a dip coating method. The coated area was from a position 2 mm measured from the end of the cylindrical support on the top side of the coating to the end of the cylindrical support on the bottom side of the coating. Next, by drying by heating in an oven at 100° C. for 30 minutes, an intermediate layer having a film thickness of 1.0 μm was formed.

ポリビニルブチラール（商品名：エスレックＢＸ－１、積水化学製） １０部
シクロヘキサノン ６００部
に、直径１ｍｍのガラスビーズを用いたサンドミル装置で４時間分散処理を施し、その後酢酸エチル７００部を加え、電荷発生層用分散液を得た。
この電荷発生層用塗布液を中間層の上に浸漬塗布法により塗布した。塗布した領域は、塗布上端側の円筒状支持体端部から測定して２ｍｍの位置から塗布下端側の円筒状支持体端部までであった。次に、１０分間８５℃のオーブンで加熱乾燥させることにより、膜厚０．１５μｍの電荷発生層を形成した。 Then the following ingredients:
Hydroxygallium phthalocyanine (having strong peaks at 7.4° and 28.2° (Bragg angle 2θ ± 0.2°) in CuKα characteristic X-ray diffraction) 20 parts calixarene represented by the following structural formula (1) Compound 0.2 parts

10 parts of polyvinyl butyral (trade name: S-lec BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 600 parts of cyclohexanone were subjected to dispersion treatment for 4 hours using a sand mill device using glass beads with a diameter of 1 mm, and then 700 parts of ethyl acetate was added to generate charge. A layer dispersion was obtained.
This charge generating layer coating solution was applied onto the intermediate layer by a dip coating method. The coated area was from a position 2 mm measured from the end of the cylindrical support on the top side of the coating to the end of the cylindrical support on the bottom side of the coating. Next, the film was dried by heating in an oven at 85° C. for 10 minutes to form a charge generation layer having a thickness of 0.15 μm.

下記構造式（３）で示される電荷輸送物質 ８部

熱可塑性樹脂として、下記構造式（４）／下記構造式（５）（＝７／３）の共重合体（重量平均分子量＝１２０，０００） １００部
を、
ｏ－キシレン／安息香酸メチル／ジメトキシメタンを３５／２０／４５の質量比で混合した混合溶剤 １，０２０部
に溶解させ、電荷輸送層用塗布液を調製した。

Next, 72 parts of a charge transport substance represented by the following structural formula (2)

8 parts of a charge transport material represented by the following structural formula (3)

As a thermoplastic resin, 100 parts of a copolymer of the following structural formula (4) / following structural formula (5) (= 7/3) (weight average molecular weight = 120,000),
The mixture was dissolved in 1,020 parts of a mixed solvent of o-xylene/methyl benzoate/dimethoxymethane at a mass ratio of 35/20/45 to prepare a coating liquid for charge transport layer.

This charge transport layer coating solution was applied onto the charge generation layer by dip coating. The coated area was from a position 2 mm measured from the end of the cylindrical support on the top side of the coating to the end of the cylindrical support on the bottom side of the coating.
At this time, as will be described later, the pulling speed of the cylindrical support is adjusted so that after drying by heating in an oven, the film thickness of the charge transport layer is 40 μm on average at the portion in contact with the charging roller 110 . bottom. In this embodiment, when the cylindrical support is pulled up to a predetermined position in the axial direction, the operation is performed as follows.

Step 1 The pull speed was linearly increased by 0.5% while the cylindrical support was raised by 12 mm relative to the adjusted pull speed described above. Subsequently, the pulling speed was linearly decreased by 0.5% while the cylindrical support was raised by 12 mm to return to the previously adjusted pulling speed.
Thereafter, step 1 described above was successively performed six times.
Thereafter, the adjusted pull rate was maintained as described above.
Next, it was dried by heating in an oven at 120° C. for 60 minutes.
Thus, an electrophotographic photoreceptor (photoreceptor-1) of Example 1 was obtained.

<Measurement of film thickness of charge transport layer of electrophotographic photoreceptor>
In order to measure the film thickness of the charge transport layer of the obtained electrophotographic photoreceptor (photoreceptor-1), measurement was carried out by an optical interference method capable of non-contact and non-destructive measurement. For the measurement, a spectral interference displacement type multilayer film thickness measuring instrument SI-T10 manufactured by Keyence Corporation was used. Measurement points were 171 points in the axial direction of the electrophotographic photosensitive member at 2 mm intervals from the center of the electrophotographic photosensitive member (range of ±170 mm from the center), and 96 points around the circumference (3.75 degree intervals). .
The average value of 96 points in the circumferential direction was taken as the film thickness of the charge transport layer at that axial position.
When the film thickness was measured at 171 points in the axial direction, seven protrusions were formed as shown in FIG. 1(B). At this time, the average film thickness of the charge transport layer in the portion contacting the charging roller of the electrophotographic apparatus described later was 40.2 μm.
After that, when the height and inclination of the formed protrusions and the width L between adjacent vertices were calculated as described above, the height was 0.12 μm, the inclination was 0.010 μm/mm, and L was 24 mm. .

<Evaluation of actual machine of electrophotographic photoreceptor (photoreceptor-1)>
Photoreceptor-1 was mounted on the cyan station of a modified electrophotographic apparatus (complex machine) manufactured by Canon Inc. (trade name: iR-ADV C3330), which was used as the evaluation apparatus, and the following tests and evaluations were performed. gone.
Under the environment of 23.0° C./50% RH, the conditions of the charging device and the image exposing device were set so that the electrophotographic photosensitive member had a dark potential (Vd) of −500 V and a light potential (Vl) of −180 V. , the initial potential of the electrophotographic photoreceptor was adjusted.
Next, roughness and image streaks were evaluated using the following methods.

<Rough evaluation>
Screen images with a cyan density of 30% were output as halftone images on 50 sheets, and roughness on the images was ranked and evaluated according to the following evaluation criteria. Then, among the evaluations of 50 sheets, the case with the lowest rank was evaluated as roughness.
A: Roughness does not occur on the image.
B: Roughness is not visible on the image, but it is at a level that can be confirmed by magnifying and observing.
C: Slight roughness occurs on the image, but the image is at an acceptable level.
D: Obvious roughness occurs on the image. The image level is unacceptable. Table 1 shows the results obtained.

<Image streak>
Screen images with a cyan density of 30% were output as halftone images on 20 sheets, and streaks on the images were ranked and evaluated according to the following evaluation criteria. Then, among the evaluations on 20 sheets, the case with the lowest rank was used as the evaluation of image streaks.
A: No streak occurs on the image.
B: A level in which an image with suspected streaks is obtained, but it cannot be clearly determined whether or not it is a streak.
C: Slight streaks occur on the image, but the image is at a permissible level.
D: Clear streaks appear on the image. The image level is unacceptable.
Table 1 shows the results obtained.
The evaluation results in Table 1 are represented by roughness/image streaks.

[Example 2]
<Preparation of Electrophotographic Photoreceptor (Photoreceptor-2)>
In Example 2, an electrophotographic photoreceptor was produced in the same manner as in Example 1, and the thickness of the charge transport layer of the electrophotographic photoreceptor was measured and the electrophotographic photoreceptor was evaluated in the same manner as in Example 1.
However, in Example 2, the dip coating of the charge transport layer was carried out as follows.
When the cylindrical support is lifted into position axially,
Step 1: The pulling speed was linearly increased by 0.5% while the cylindrical support was raised by 12 mm relative to the above adjusted pulling speed. Subsequently, the pulling speed was linearly decreased by 0.5% while the cylindrical support was raised by 12 mm to return to the previously adjusted pulling speed.
The operation as described above was performed twice in succession.
after that,
Step 2: Maintain the aforementioned adjusted pull rate while the cylindrical support is raised by 6 mm.
After that, Step 1→Step 2→Step 1 were performed in the same manner as described above, and thereafter the adjusted pulling speed was maintained.

When the film thickness of the charge transport layer of the obtained electrophotographic photoreceptor (photoreceptor-2) was measured in the same manner as in Example 1, as shown in FIG. was formed, then two protrusions were formed continuously with an interval of 6 mm, and then similarly two protrusions were continuously formed with an interval of 6 mm. At this time, the average film thickness of the charge transport layer in the portion that contacts the charging roller of the electrophotographic device was 40.3 μm.
After that, the height and inclination of the formed protrusions and the width L between adjacent vertices were calculated as described above. The L between the projections formed at intervals was 24 mm, and the L between the projections formed at intervals was 30 mm.
Also, the electrophotographic photoreceptor (photoreceptor-2) was evaluated in the same manner as in Example 1.
Table 1 shows the results obtained.

[Example 3]
<Preparation of Electrophotographic Photoreceptor (Photoreceptor-3)>
In Example 3, an electrophotographic photoreceptor was produced in the same manner as in Example 1, and the thickness of the charge transport layer of the electrophotographic photoreceptor was measured and the electrophotographic photoreceptor was evaluated in the same manner as in Example 1.
However, in Example 3, the dip coating of the charge transport layer was carried out as follows.
When the cylindrical support is lifted into position axially,
Step 1: The pulling speed was linearly increased by 0.5% while the cylindrical support was raised by 12 mm relative to the above adjusted pulling speed. Subsequently, the pulling speed was linearly decreased by 0.5% while the cylindrical support was raised by 12 mm to return to the previously adjusted pulling speed. after that,
Step 3: Maintain the aforementioned adjusted pull rate while the cylindrical support is raised by 20 mm.
Thereafter, steps 1 to 3 were repeated five times in the same manner as described above, and then step 1 was performed, after which the above-described adjusted pulling speed was maintained.

When the film thickness of the charge transport layer of the obtained electrophotographic photoreceptor (photoreceptor-3) was measured in the same manner as in Example 1, as shown in FIG. was formed. At this time, the average film thickness of the charge transport layer in the portion in contact with the charging roller of the electrophotographic device was 40.2 μm.
After that, when the height and inclination of the formed protrusions and the width L between adjacent vertices were calculated as described above, the height was 0.12 μm, the inclination was 0.010 μm/mm, and L was 21 mm. .
Also, an electrophotographic photoreceptor (photoreceptor-3) was evaluated in the same manner as in Example 1.
Table 1 shows the results obtained.

[Comparative Example 1]
<Production of electrophotographic photoreceptor (photoreceptor-30)>
In Comparative Example 1, an electrophotographic photoreceptor was produced in the same manner as in Example 1, and the thickness of the charge transport layer of the electrophotographic photoreceptor was measured in the same manner as in Example 1, and the actual machine evaluation of the electrophotographic photoreceptor was performed.
However, in this Comparative Example 1, the dip coating of the charge transport layer was carried out as follows.
The cylindrical support was pulled up at the adjusted pulling speed mentioned above. That is, steps like those of Examples 1, 2, and 3 were not performed.
The film thickness of the charge transport layer of the resulting electrophotographic photoreceptor (photoreceptor-30) was measured in the same manner as in Example 1. As in Examples 1 and 2, it was formed continuously in the circumferential direction. No convex portion having a predetermined height and inclination was formed.

As is clear from Table 1, in the DC charging type electrophotographic apparatus, the electrophotographic photosensitive member has an average film thickness of 30 μm or more at the portion of the charge transport layer in contact with the charging roller, and the surface of the charge transport layer has a convex portion continuously formed in the circumferential direction of the electrophotographic photosensitive member and having a height of 0.1 μm to 0.2 μm and an inclination of 0.007 μm/mm to 0.020 μm/mm. The electrophotographic apparatus, wherein a plurality of portions are present in a portion where the charging roller abuts in the axial direction of the electrophotographic photosensitive member, and L is 10 mm to 60 mm or less, where L is the width between adjacent vertexes of the convex portions. By using , it is possible to suppress the occurrence of roughness in the initial period of use of the electrophotographic apparatus. Furthermore, when Example 1, Example 2 and Example 3 were compared, Example 1 and Example 2 had better roughness. The reason for this is presumed as follows.

Since the charging roller 110 is structured to press against the electrophotographic photosensitive member 100 at both ends, the pressing pressure is weaker at the center than at the ends. Therefore, it is presumed that the contact surface between the charging roller 110 and the electrophotographic photosensitive member 100 is more stabilized when the convex portions are concentrated near the center in the axial direction as in the first and second embodiments. be done.

[Example 4]
<Production of electrophotographic photoreceptors (photoreceptor-4) to (photoreceptor-12)>
In this example, an electrophotographic photoreceptor was produced in the same manner as in Example 1.
However, in Example 4, the dip coating of the charge transport layer was carried out as follows.
As in Example 1, as shown in FIG. 1B, a convex portion (120d in the drawing) is provided at the center of the portion in contact with the charging roller in the axial direction of the electrophotographic photosensitive member, and the convex portion (120d in the drawing) is continuously formed from there. A configuration was adopted in which the convex portions were provided so as to be symmetrical. The protrusions were formed so that one protrusion could be completely accommodated in the axial portion of the electrophotographic photosensitive member with which the charging roller abuts. In other words, the bottom point 1 - top point 1 - bottom point 2 were all formed so as not to be cut in the middle.
The projections are formed in the same manner as in step 1 of Example 1, but at this time, the rate of increase and decrease of the pulling speed and the distance at which the pulling speed is raised and lowered are varied to obtain 9 types of electrophotographic exposure. made the body. Then, the film thickness of the charge transport layer was measured in the same manner as in Example 1, and the height and inclination of the projections of each electrophotographic photosensitive member, and the width L between adjacent vertices were measured in the same manner as in Example 1. calculated as

The height, inclination, and width L between adjacent vertices of the obtained convex portions are shown below.
Photoreceptor-4 Height = 0.10 µm Tilt = 0.007 µm/mm L = 29.0 mm
Photoreceptor-5 Height = 0.10 µm Tilt = 0.015 µm/mm L = 13.5 mm
Photoreceptor-6 Height = 0.10 µm Tilt = 0.020 µm/mm L = 10.0 mm
Photoreceptor-7 Height = 0.15 µm Tilt = 0.007 µm/mm L = 43.0 mm
Photoreceptor-8 Height = 0.15 µm Tilt = 0.015 µm/mm L = 20.0 mm
Photoreceptor-9 Height = 0.15 µm Tilt = 0.020 µm/mm L = 15.0 mm
Photoreceptor-10 Height = 0.20 µm Tilt = 0.007 µm/mm L = 57.1 mm
Photoreceptor-11 Height = 0.20 µm Tilt = 0.015 µm/mm L = 26.7 mm
Photoreceptor-12 Height = 0.20 µm Tilt = 0.020 µm/mm L = 20.0 mm
The obtained electrophotographic photoreceptors ((Photoreceptor-4) to (Photoreceptor-12)) were evaluated for roughness and image streaks in the same manner as in Example 1.
Table 2 shows the results obtained. In addition, the evaluation results in Table 2 are represented by roughness/image streaks.

[Comparative Example 2]
<Production of electrophotographic photoreceptors (photoreceptor-13) to (photoreceptor-28)>
In this comparative example, an electrophotographic photoreceptor was produced in the same manner as in Example 4.
However, in Comparative Example 2, the height and inclination of the projections of the electrophotographic photosensitive member, and the width L between adjacent vertices were formed as follows.
Photoreceptor-13 Height = 0.05 µm Tilt = 0.004 µm/mm L = 25.0 mm
Photoreceptor-14 Height = 0.05 µm Tilt = 0.007 µm/mm L = 14.3 mm
Photoreceptor-15 Height = 0.05 µm Tilt = 0.015 µm/mm L = 6.7 mm
Photoreceptor-16 Height = 0.05 µm Tilt = 0.020 µm/mm L = 5.0 mm
Photoreceptor-17 Height = 0.05 µm Tilt = 0.030 µm/mm L = 3.3 mm
Photoreceptor-18 Height = 0.10 µm Tilt = 0.004 µm/mm L = 50.0 mm
Photoreceptor-19 Height = 0.10 µm Tilt = 0.030 µm/mm L = 6.7 mm
Photoreceptor-20 Height = 0.15 µm Tilt = 0.004 µm/mm L = 75.0 mm
Photoreceptor-21 Height = 0.15 µm Tilt = 0.030 µm/mm L = 10.0 mm
Photoreceptor-22 Height = 0.20 µm Tilt = 0.004 µm/mm L = 100.0 mm
Photoreceptor-23 Height = 0.20 µm Tilt = 0.030 µm/mm L = 13.3 mm
Photoreceptor-24 Height = 0.30 µm Tilt = 0.004 µm/mm L = 150.0 mm
Photoreceptor-25 Height = 0.30 µm Tilt = 0.007 µm/mm L = 85.7 mm
Photoreceptor-26 Height = 0.30 µm Tilt = 0.015 µm/mm L = 40.0 mm
Photoreceptor-27 Height = 0.30 µm Tilt = 0.020 µm/mm L = 30.0 mm
Photoreceptor-28 Height = 0.30 µm Tilt = 0.030 µm/mm L = 20.0 mm
In the same manner as in Example 4, the obtained electrophotographic photoreceptors ((Photoreceptor-13) to (Photoreceptor-28)) were evaluated for roughness and image streaks.
Table 2 shows the results obtained.

As is clear from Table 2, the electrophotographic photosensitive member has an average film thickness of 30 μm or more at the portion of the charge transport layer that is in contact with the charging roller. There is a continuously formed convex portion having a height of 0.1 μm to 0.2 μm and an inclination of 0.007 μm/mm to 0.020 μm/mm. A plurality of protrusions are present in a portion with which the charging roller abuts, and L is 10 mm to 60 mm or less, where L is the width between adjacent vertexes of the protrusions. It is possible to suppress the occurrence of roughening in the initial period of use of the electrophotographic apparatus while keeping it in place. Furthermore, by setting the inclination to 0.007 μm/mm to 0.015 μm/mm, it is possible to further suppress the occurrence of image streaks.

[Example 5]
<Preparation of Electrophotographic Photoreceptor (Photoreceptor-29)>
In Example 5, an electrophotographic photoreceptor was produced in the same manner as in Example 3, and the film thickness of the charge transport layer of the electrophotographic photoreceptor was measured and the electrophotographic photoreceptor was evaluated in the same manner as in Example 3.
However, in Example 5, the dip coating of the charge transport layer was carried out as follows.
When the cylindrical support is lifted into position axially,
Step 1: The pulling speed was linearly increased by 0.5% while the cylindrical support was raised by 12 mm relative to the above adjusted pulling speed. Subsequently, the pulling speed was linearly decreased by 0.5% while the cylindrical support was raised by 12 mm to return to the previously adjusted pulling speed.
after that,
Step 4: Maintain the above adjusted pull rate while the cylindrical support is raised by 36 mm.
Thereafter, steps 1 to 4 were repeated 3 times in the same manner as described above, after which step 1 was carried out, after which the above-described adjusted pulling speed was maintained.

When the film thickness of the charge transport layer of the resulting electrophotographic photosensitive member (photosensitive member-29) was measured in the same manner as in Example 1, discrete projections were formed as shown in FIG. 1(D). rice field. However, five protrusions were formed in total. At this time, the average film thickness of the charge transport layer in the portion in contact with the charging roller of the electrophotographic device was 40.2 μm.
After that, when the height and inclination of the formed protrusions and the width L between adjacent vertices were calculated as described above, the height was 0.12 μm, the inclination was 0.010 μm/mm, and L was 60 mm. .
In the same manner as in Example 1, an electrophotographic photoreceptor (photoreceptor-29) was evaluated using an actual machine.
The obtained results are shown in Table 3 together with Example 3 and Comparative Example 3 described later.

[Comparative Example 3]
<Preparation of Electrophotographic Photoreceptor (Photoreceptor-31)>
In Comparative Example 3, an electrophotographic photoreceptor was produced in the same manner as in Example 5, and the thickness of the charge transport layer of the electrophotographic photoreceptor was measured and the electrophotographic photoreceptor was evaluated in the same manner as in Example 5.
However, in Comparative Example 3, dip coating of the charge transport layer was carried out as follows.
When the cylindrical support is lifted into position axially,
Step 1: The pulling speed was linearly increased by 0.5% while the cylindrical support was raised by 12 mm relative to the above adjusted pulling speed. Subsequently, the pulling speed was linearly decreased by 0.5% while the cylindrical support was raised by 12 mm to return to the previously adjusted pulling speed.
after that,
Step 5: Maintain the above adjusted pull rate while the cylindrical support is raised 41 mm.
Thereafter, steps 1 to 5 were repeated three times in the same manner as described above, and then step 1 was performed, after which the above-described adjusted pulling speed was maintained.

When the film thickness of the charge transport layer of the obtained electrophotographic photoreceptor (photoreceptor-31) was measured in the same manner as in Example 5, discrete convex portions were formed as shown in FIG. 1(D). rice field. However, five protrusions were formed in total. At this time, the average film thickness of the charge transport layer at the portion in contact with the charging roller of the electrophotographic device was 40.2 μm.
After that, when the height and inclination of the formed protrusions and the width L between adjacent vertices were calculated as described above, the height was 0.12 μm, the inclination was 0.010 μm/mm, and L was 65 mm. .
Also, an electrophotographic photoreceptor (photoreceptor-31) was evaluated in the same manner as in Example 1.
Table 3 shows the results obtained.

As is clear from Table 3, when L is the width between adjacent vertices of the projections, L is 60 mm or less. can be suppressed.
Further, as is clear from Table 2, when L is smaller than 10 mm, the height and inclination of the convex portion are the same as those of the present invention of 0.1 μm to 0.2 μm and inclination of 0.007 μm/mm to 0.007 μm/mm. .020 μm/mm cannot be satisfied.
Therefore, there are a plurality of projections in the axial direction of the electrophotographic photosensitive member, where the charging roller abuts, and L is the width between adjacent vertices of the projections. By using the photographic apparatus, it is possible to suppress the occurrence of roughness in the early stage of use of the electrophotographic apparatus.

100 Electrophotographic photosensitive member 101 Support 102 Undercoat layer 103 Charge generation layer 104 Charge transport layer 110 Charging roller 301 Process cartridge 302 Shaft 303 Charging means 304 Developing means 305 Guiding means 306 Transfer means 307 Transfer material 308 Cleaning means 310 Fixing Means 311 Exposure light 312 Pre-exposure light

Claims (4)

an electrophotographic photoreceptor having a cylindrical support, a charge generation layer and a charge transport layer in this order, the charge transport layer being a surface layer;
a charging roller for charging the electrophotographic photosensitive member;
a power source that applies only a DC voltage to the charging roller;
An electrophotographic apparatus having
The average film thickness of the charge transport layer at a portion where the charging roller contacts the charge transport layer is 30 μm or more,
On the surface of the charge transport layer, a charge transport layer having a height of 0.1 μm or more and 0.2 μm or less and an inclination of 0.007 μm/mm or more and 0.020 μm/mm is continuously formed in the circumferential direction of the electrophotographic photosensitive member. There is a convex part of mm or less,
a plurality of the convex portions are present in a portion in the axial direction of the electrophotographic photosensitive member with which the charging roller abuts;
L is 10 mm or more and 60 mm or less, where L is the width between adjacent vertices of the protrusions.
An electrophotographic apparatus characterized by: 2. The electrophotographic apparatus according to claim 1, wherein the inclination of said convex portion is 0.007 [mu]m/mm or more and 0.015 [mu]m/mm or less. The surface of the charge transport layer has a region A in which the convex portions are continuously provided,
The region A is provided in the central portion in the axial direction of the electrophotographic photosensitive member,
The length of the region A is 2/5 or more of the length in the axial direction of the contact surface between the electrophotographic photosensitive member and the charging roller.
3. The electrophotographic apparatus according to claim 1. A plurality of regions B in which the convex portions are continuously provided are provided on the surface of the charge transport layer,
The region B includes a region Bc and a region Be other than the region Bc,
the length of the region B is 1/5 or less of the length in the axial direction of the contact surface between the electrophotographic photosensitive member and the charging roller;
The region Bc is provided in the central portion in the axial direction of the electrophotographic photosensitive member,
3. The electrophotographic apparatus according to claim 1, wherein said region Be is adjacent to said region Bc and provided at regular intervals with respect to said region Bc in the axial direction of said electrophotographic photosensitive member.

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