JPH11202531A - Electrophotographic photoreceptor and electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has a surface layer having an excellent release property and excellent durability to wear and flaws, is free of the degradation in surface resistance by adhesion of active materials in spite of repetitive use, is substantially free of the accumulation of residual potential and the degradation in sensitivity in spite of repetitive use, exhibits stable electrophotographic characteristics, hardly produce transfer memories in spite of a reversal development system and is capable of maintaining high-grade images even under high humidity and an electrophotographic image forming device having the photoreceptor. SOLUTION: This electrophotographic photoreceptor is the electrophotographic photoreceptor having a photosensitive layer and a protective layer on a base. The protective layer contains colloidal silica and siloxane resin and contains the conductive particles subjected to a surface treatment by a fluorine atom-contg. compd. and fluorine atom-contg. resin particles. The electrophotographic image forming device has the photoreceptor described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member which can be widely used in a copying machine, a printer, a facsimile, a plate making system and the like using an electrophotographic system, and an electrophotographic image forming apparatus having the same. More specifically, an electrophotograph having a surface protective layer having excellent charge stability, high image uniformity, excellent durability such as abrasion resistance, and excellent contamination resistance and slipperiness due to low surface energy. The present invention relates to a photoconductor and an electrophotographic image forming apparatus having the same.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors, of course, have required sensitivity, electrical characteristics, optical characteristics, and the like according to the electrophotographic process to be applied. The surface is directly subjected to an electrical or mechanical influence by a charging process such as corona charging and roller charging, a developing process, a transfer process, a cleaning process, and the like, so that the surface thereof is required to have durability.

More specifically, durability is required against abrasion and scratches on the surface of the photoreceptor due to rubbing, and deterioration of the surface of the electric photoreceptor, which is likely to occur during charging under high humidity. In particular, in a charging method using a discharge phenomenon such as a roller charging method, durability against high-energy arc discharge is required.

There is also a problem that toner adheres to the surface of the photoreceptor due to repetition of development and cleaning with the toner. For this purpose, improvement in the cleaning property of the surface of the photoreceptor is required.

[0005] In order to satisfy the various characteristics required for the photoreceptor surface as described above, attempts have been made to provide a surface protective layer mainly composed of various resins on the photosensitive layer. For example, JP-A-57-30843 proposes a protective layer in which resistance is controlled by adding metal oxide particles as conductive particles.

It has also been studied to improve the physical properties of the photoreceptor surface by adding various substances to the charge transport layer as well as the protective layer. For example, the following are reported as additives focusing on low surface energy of silicone resins.

[0007] Silicone oil (JP-A-61-1329)
No. 54), polydimethylsiloxane, silicone resin powder (JP-A-4-324454), crosslinked silicone resin, poly (carbonate silicon) block copolymer, silicone-modified polyurethane, silicone-modified polyester, thermosetting silicone resin (Tokuhei 5-46
No. 940) As a typical polymer having a low surface energy, there is a fluoropolymer, and the following can be added as the fluoropolymer.

[0008] Polytetrafluoroethylene powder, carbon fluoride powder [0008] However, a surface protective layer containing a metal oxide or the like can have a considerable hardness, but has a problem in cleaning properties and the like because the surface energy is easily increased. is there.

Further, the conventional methods have problems in dispersibility and cohesiveness of the metal oxide particles in the binder resin, and in conductivity and transparency when used for the protective layer. In addition, phenomena such as image defects due to non-uniformity or unevenness, increase in residual potential due to repeated charging, and decrease in sensitivity were likely to occur.

Further, dispersing metal oxide particles in a protective layer for an electrophotographic photoreceptor controls the electric resistance of the protective layer itself and prevents an increase in residual potential in the photoreceptor during repetition of the electrophotographic process. Is the main purpose, while a suitable resistance of the protective layer for the electrophotographic photoreceptor is 10 ¹⁰
10 to 10 ¹⁵ Ω · cm. However, in the resistance value in the above-mentioned range, the electric resistance of the protective layer is easily affected by ionic conduction, and therefore, the electric resistance tends to largely change due to a change in environment. In particular, when metal oxide particles are dispersed in a film, since the surface of the metal oxide particles has high water absorption, the resistance of the protective layer is increased in all environments and when the electrophotographic process is repeated. Has been very difficult to keep within the above range.

In general, when particles are dispersed in the protective layer, in order to prevent scattering of the incident light by the dispersed particles, the particle diameter of the particles must be smaller than the wavelength of the incident light, that is, 0.1.
It needs to be 3 μm or less. However, metal oxide particles generally have a strong tendency to aggregate in a resin solution, making uniform dispersion difficult, and secondary aggregation and sedimentation occur even once dispersed, producing a stable dispersion film of 0.3 μm or less. It was very difficult to do. Further, in order to improve transparency and conductivity uniformity, it is effective to disperse ultrafine particle powder having a finer particle size (primary particle size of 0.1 μm or less). Dispersibility and dispersion stability tended to be poor. Furthermore, particularly in high humidity, causing a decrease in the surface resistance of the photosensitive member by such corona products of ozone and NO _X or the like generated adheres to the surface by repeated charging, yet the problem that image deletion occurs At present, no protective layer having satisfactory electrophotographic properties has been obtained.

[0012]

In order to make up for the above-mentioned drawbacks, for example, JP-A-1-306857 discloses the addition of a compound such as a fluorine-containing silane coupling agent, a titanate coupling agent or C ₇ H ₁₅ NCO. JP-A-62-295066 discloses a protective layer in which a binder resin is dispersed with a metal fine powder or a metal oxide fine powder having improved dispersibility and moisture resistance by performing a water-repellent treatment. JP-A-2-50167 proposes a protective layer in which a titanate coupling agent, a fluorine-containing silane coupling agent and a metal oxide fine powder surface-treated with acetoalkoxyaluminum diisopropylate are dispersed in a binder resin. Have been.

[0013] However, even in these protective layers, releasability of the binder resin itself to be used in the protective layer, durability against wear and scratches due to rubbing, more durable against for active substances such as ozone and NO _X However, at present, a protective layer having satisfactory electrophotographic properties has not yet been obtained as a protective layer that responds to high image quality in recent years.

Furthermore, with the recent increase in durability and image quality of the photoconductor, a new problem has been pointed out as a photoreceptor pause memory phenomenon. The pause memory phenomenon is basically one of the degradation phenomena caused by corona products.However, after the copy is completed, the rotation of the photoreceptor stops, and the charging ability of the portion stopped near the corona charger decreases, and In the case of development, the image density decreases only in that portion, and in the case of reversal development, the image density increases. This phenomenon is likely to occur after the photoconductor has been used for a long time, and has become a more serious problem as the life of the photoconductor is extended. In addition, in the reversal development system corresponding to recent digitization, since the primary charging and the transfer charging have opposite characteristics, a so-called transfer memory having different charging characteristics depending on the presence or absence of transfer occurs, which is very apparent as density unevenness on an image. It's easier.

On the other hand, as an attempt to improve the physical properties of the photoreceptor surface by adding various substances to the charge transport layer, addition of a silicone resin is cited, and the silicone resin is excellent in that the surface energy is small. However, since it does not show sufficient compatibility with other resins, there is a problem that the added system easily aggregates and causes light scattering, or does not show stable characteristics because it bleeds and segregates on the surface. . In addition, when the silicone resin alone is used, the hardness is insufficient, and when a solvent system that does not attack the photosensitive layer, for example, alcohol or water, is used, the surface energy of the silicone resin tends to be large. There is a problem in cleaning performance and the like.

In addition, fluoropolymers represented by polytetrafluoroethylene, which are low surface energy polymers, are generally insoluble in solvents and have poor dispersibility, so that a smooth photoreceptor surface can be obtained. Difficulty and low refractive index tend to cause light scattering, which causes a problem of deterioration of the latent image.

In addition, polymer compounds such as polycarbonate, polyacrylester, polyester, and polytetrafluoroethylene generally have insufficient arc discharge resistance and are easily degraded because the polymer main chain is cut by discharge. There was a problem.

Accordingly, an object of the present invention is to firstly provide a high-quality image having a surface layer having excellent release properties and having excellent durability against abrasion and scratches. An object of the present invention is to provide an electrophotographic photosensitive member that can be maintained and an electrophotographic image forming apparatus having the photosensitive member.

Secondly, there is provided an electrophotographic photoreceptor capable of maintaining a high-quality image even under high humidity without causing a decrease in surface resistance due to adhesion of an active substance caused by repeated use, and an electrophotographic photoreceptor. An object of the present invention is to provide an electrophotographic image forming apparatus.

Third, there is provided an electrophotographic photosensitive member exhibiting stable electrophotographic characteristics in which accumulation of residual potential and reduction in sensitivity are unlikely to occur even when used repeatedly, and an electrophotographic image forming apparatus having the photosensitive member. It is in.

A fourth object of the present invention is to provide an electrophotographic photosensitive member in which transfer memory is unlikely to occur even in a reversal developing system, and an electrophotographic image forming apparatus having the photosensitive member.

Fifth, it is an object of the present invention to provide an electrophotographic photosensitive member which does not cause a pause memory phenomenon and an electrophotographic image forming apparatus having the photosensitive member.

[0023]

That is, a first aspect of the present invention is to provide an electrophotographic photosensitive member having a photosensitive layer and a protective layer on a support, wherein the protective layer contains colloidal silica and a siloxane resin; And an electrophotographic photoreceptor comprising conductive particles surface-treated with a fluorine atom-containing compound and fluorine atom-containing resin particles.

The siloxane resin described in the present invention means a silicone resin obtained by condensation of a silicon compound having three hydrolyzable groups such as an OH group and an OR group per silicon atom, or a partially condensed oligomer.

According to a second aspect of the present invention, there is provided an electrophotographic image forming apparatus which forms a latent image on an electrophotographic photosensitive member by exposure and develops the formed latent image to obtain an image. Has means for charging the photoreceptor and means for developing the obtained latent image with toner, wherein the photoreceptor is an electrophotographic photoreceptor having a photosensitive layer and a protective layer on a support, An electrophotographic image forming apparatus, wherein the protective layer contains colloidal silica and a siloxane resin, and contains conductive particles and fluorine atom-containing resin particles surface-treated with a fluorine atom-containing compound.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The protective layer of the electrophotographic photosensitive member of the present invention contains colloidal silica and a siloxane resin, and contains conductive particles and fluorine atom-containing resin particles surface-treated with a fluorine atom-containing compound. The electrophotographic photoreceptor of the present invention is formed by applying the composition for a protective layer on the surface of the photosensitive layer, drying and curing.

The composition for a protective layer used in the present invention comprises at least the following five components (a) to (e). (A) colloidal silica (b) siloxane resin formed by partial condensation of R—Si (OR ′) ₃ (wherein R is an alkyl group having 1 to 3 carbon atoms, a vinyl group,
_{n F 2n + 1 C 2 H} 4 - group (n = 1~18), representing the γ- glycidoxypropyl group and γ- methacryloxypropyl least one group selected from the group consisting of propyl group.
R 'represents at least one group selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 3 carbon atoms. (C) at least one solvent selected from the group consisting of lower aliphatic alcohols and water; (d) conductive particles surface-treated with a fluorine atom-containing compound; and (e) fluorine atom-containing resin particles. The composition for a body protective layer is preferably a composition in which colloidal silica and a siloxane resin are dispersed in a 1 to 50% by weight lower alcohol-water mixed solution. If the solids content exceeds 50% by weight, the composition is liable to be deteriorated, and it is difficult to form a good coating film due to gelation or the like. 1
If the amount is less than the weight percentage, the strength of the formed protective layer tends to be insufficient.

The proportion of colloidal silica in the solid content is preferably from 10 to 70% by weight, and the content of the siloxane resin is preferably from 30 to 90% by weight. If the ratio of the siloxane resin to the solid content is less than 30% by weight, the film tends to be brittle and a good film is not easily formed, and cracks and the like tend to be easily formed. If the ratio of the colloidal silica is less than 10% by weight, the hardness of the formed protective layer is low. Tend to be insufficient.

As the colloidal silica, a commercially available aqueous dispersion type is used (trade names “Ludox” and “Na”).
lcoag "). The particle size is preferably from 5 to 150 nm, and from the viewpoint of dispersion stability and optical characteristics, from 10 nm to 30 nm.
nm is more preferable. As colloidal silica, the content of an alkali metal oxide such as Na ₂ O is preferably less than 2% by weight. As the dispersing solvent, a mixed solvent system of water and a lower aliphatic alcohol such as methanol, ethanol, isopropanol, t-butanol and n-butanol is preferable, but other water-soluble solvents such as glycol and acetone may be further added. Good.

The conductive particles used in the present invention include:
Examples include metals, metal oxides, and carbon black. Metals include aluminum, zinc, copper, chrome,
Examples thereof include nickel, stainless steel, silver, and the like, and those obtained by vapor-depositing these metals on the surfaces of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and antimony-doped zirconium oxide. These can be used alone or in combination of two or more. When two or more kinds are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion.

The average particle size of the conductive particles used in the present invention is preferably 0.3 μm or less, particularly preferably 0.1 μm or less from the viewpoint of the transparency of the protective layer.

In the present invention, among the above-described conductive particles, it is particularly preferable to use a metal oxide from the viewpoint of transparency and the like.

The fluorine atom-containing resin particles used in the present invention include ethylene tetrafluoride resin, ethylene trifluoride ethylene resin, ethylene hexafluoride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, It is preferable to appropriately select one or more of ethylene chloride resins and copolymers thereof, and particularly preferable are tetrafluoroethylene resins and vinylidene fluoride resins.
The molecular weight of the resin particles and the particle size of the particles can be appropriately selected and are not particularly limited.

In the present invention, the surface of the conductive particles is treated with a fluorine atom-containing compound so that the conductive particles and the fluorine atom-containing resin particles are not aggregated in a resin solution. By performing the surface treatment, the dispersibility and dispersion stability of the conductive particles and the fluorine atom-containing resin particles in the resin solution were remarkably improved as compared with the case where the surface treatment was not performed. Further, by dispersing the conductive particles and the fluorine atom-containing resin particles subjected to the surface treatment with the fluorine atom-containing compound in a binder resin dissolved in a solvent, secondary particles of the dispersed particles are not formed, and the Thus, a very stable coating liquid having good dispersibility was obtained.

In the present invention, when the conductive particles are subjected to a surface treatment with a fluorine atom-containing compound, examples of the fluorine atom-containing compound that can be used include a fluorinated silane coupling agent, a fluorine-modified silicone oil, and a fluorine-based surfactant. Can be Hereinafter, preferred compounds are exemplified, but the invention is not limited to these compounds.

Preferred examples of the fluorine-containing silane coupling agent include CF ₃ CH ₂ CH ₂ Si (OC
_{H 3) 3, C 4 F} 9 CH 2 CH 2 Si (OCH 3) 3,
C ₆ F ₁₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₈ F ₁₇ C
H ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₈ F ₁₇ CH ₂ CH ₂
Si (OCH ₂ CH ₂ OCH ₃ ) ₃ , C ₁₀ F ₂₁ Si (O
CH ₃ ) ₃ , C ₆ F ₁₃ CONHSi (OCH ₃ ) ₃ , C
₈ F ₁₇ CONHSi (OCH ₃ ) ₃ , C ₇ F ₁₅ CONH
CH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₇ F ₁₅ CO
NHCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ , C ₇ F
₁₅ COOCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₇
F ₁₅ COSCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C
_{8 F 17 SO 2 NHCH 2 CH} 2 CH 2 Si (OC
₂ H _{5) 3,}

[0038]

[Outside 1] C ₈ F ₁₇ CH ₂ CH ₂ SCH ₂ CH ₂ Si (OCH ₃ )
₃ , C ₁₀ F ₂₁ CH ₂ CH ₂ SCH ₂ CH ₂ Si (OCH
₃ ) ₃ ,

[0039]

[Outside 2]

[0040]

[Outside 3] And the like.

Preferred examples of the fluorine-modified silicone oil include:

[0042]

[Outside 4] Is mentioned. Here, R in the formula is -CH ₂ CH ₂ CF ₃
And m and n are positive integers.

Preferred examples of the fluorine-based surfactant include X-SO ₂ NRCH ₂ COOH and X-SO ₂ NRC
H ₂ CH ₂ O (CH ₂ CH ₂ O) _n H (n = 5, 10,
_{15), X-SO 2 N} (CH 2 CH 2 CH 2 OH) 2,
X-RO (CH ₂ CH ₂ O) _n (n = 5, 10, 1)
5), X- (RO) _n (n = 5 to 20), X- (RO)
_n R (n = 5 to 20),

[0044]

[Outside 5]

[0045]

[Outside 6]

[0046]

[Outside 7]

[0047]

[Outside 8] And the like. However, R in the formula is an alkyl group, an allyl group or an aralkyl group, and X is -CF ₃ , -C ₄ F ₉
Or an carbon fluoride group such as -C ₈ F _17.

The method for treating the surface of the conductive particles is as follows. First, the conductive particles and the surface treating agent are mixed and dispersed in an appropriate solvent, and the surface treating agent is attached to the surface of the conductive particles. As the dispersing means, ordinary dispersing means such as a ball mill and a sand mill can be used. Next, the solvent may be removed from the dispersion solution, and the surface treatment agent may be fixed to the surface of the conductive particles. Further, if necessary, heat treatment may be performed thereafter. Further, a catalyst for accelerating the reaction may be added to the treatment liquid. Further, the conductive particles after the surface treatment may be further subjected to a pulverizing treatment, if necessary.

The ratio of the fluorine-containing compound to the conductive particles is affected by the particle size of the particles, but is preferably 1 to 65% by weight based on the total weight of the surface-treated conductive particles. Preferably it is 10 to 50% by weight.

In the present invention, additives such as a coupling agent and an antioxidant may be added to the protective layer for the purpose of improving dispersibility, binding property and weather resistance. The protective layer is formed by applying a solution of the protective layer composition in which the conductive particles and the fluorine atom-containing resin particles subjected to the surface treatment with the fluorine atom-containing compound are dispersed and cured.

Examples of the method of dispersing the conductive particles and the fluorine atom-containing resin particles subjected to the surface treatment with the fluorine atom-containing compound include a homogenizer, a ball mill, a sand mill, a roll mill, and an ultrasonic wave. There is no particular limitation as long as the particles can be dispersed up to the diameter.

The composition for the protective layer of the electrophotographic photosensitive member is preferably adjusted to an acidic state of pH 3.0 to 6.0 by using an inorganic acid or an organic acid. Since the use of a strong acid tends to adversely affect the stability and the like of the composition,
More preferably, a weak acid is used to adjust the pH to an acidic state of 4.0 to 5.5.

The composition for the protective layer of the electrophotographic photoreceptor applied to the surface of the electrophotographic photoreceptor is dried and then heat-cured to exhibit hardness, strength, low surface energy and discharge resistance. Thermal curing proceeds more completely at higher temperatures, but is selected within a range that does not adversely affect the characteristics of the electrophotographic photosensitive member. The thermosetting is preferably carried out at 80 to 180 ° C, more preferably at 100 to 150 ° C.

The longer the thermal curing time, the more the curing proceeds, but the thermal curing time is selected within a range that does not adversely affect the characteristics of the electrophotographic photosensitive member at the processing temperature. The heat curing treatment time is generally about 10 minutes to 12 hours.

After drying, the protective layer obtained by heat curing contains at least a component represented by SiO ₂ as colloidal silica and a siloxane resin represented by RSiO _3/2 .

Here, R is an alkyl group having 1 to 3 carbon atoms,
Vinyl _{group, C n F 2n + 1 C} 2 H 4 - group (n = 1~18),
represents at least one group selected from the group consisting of a γ-glycidoxypropyl group and a γ-methacryloxypropyl group.

The thickness of the protective layer is preferably 0.1 to 4 μm. If the thickness is less than 0.1 μm, the surface hardness and strength are not sufficient, and the durability tends to decrease. If the thickness exceeds 4 μm, the contrast potential formed by a latent image during development tends to deteriorate. More preferably, it is 0.2 to 3.0 μm.

The protective layer preferably has a low surface energy in order to satisfy cleaning properties and stain resistance.
The low surface energy measured by the contact angle of water is 9
0 degree or more is preferable. If the angle is less than 90 degrees, a charge product, toner, or falling off from paper is liable to adhere to the surface due to repeated use in the electrophotographic process, and deterioration of a latent image (image deletion) due to poor cleaning or a decrease in surface resistance is likely to occur. It is more preferably at least 95 degrees.

The volume resistance of the protective layer is 1 × 10 ⁹ to 1 × 10
It is preferably ¹⁵ Ωcm. If it is less than 1 × 10 ⁹ Ωcm, the charge of the formed latent image is diffused, so that it easily deteriorates.
If it exceeds 1 × 10 ¹⁵ Ωcm, the charge may not move sufficiently before development after exposure as an electrophotographic photoreceptor, so that the apparent sensitivity lowers and the residual potential tends to increase.

Since the residual potential tends to increase not only due to the potential resistance but also due to the remaining hydrolyzable groups such as silanol groups, it is desirable that the residual potential be as low as possible. Preferably, the ratio of the hydrolyzable group in terms of SiOH group is 0.1% by weight or less, more preferably 0.01% by weight or less.

For the protective layer, a resin composition containing colloidal silica and a siloxane resin as essential components is used, and these are described in US Pat. No. 4027073 and US Pat.
It can be produced by the method described in US Pat.

The silicone-based hard coat resin comprises a hydrolytic condensate of a polyfunctional organosilicon compound having a hydrolyzable group in the molecule. The greater the number of functional groups, the higher the strength, and the resulting resin becomes harder. Among them, 4
In the case of using colloidal silica in place of the functional organosilicon and using trifunctional organosilicon, the hardness is adjusted by adjusting the particle size of colloidal silica, the amount of colloidal silica added, and the hydrolytic condensation of the trifunctional organosilicon. A resin which is high and excellent in film forming properties can be obtained.

The preferred colloidal silica has an average particle diameter of 5 to 150 nm, and is dispersed in a lower alcohol containing water within the above-described range, and a trifunctional organosilicon compound having a hydrolyzable group is used. It is produced by hydrolysis in the presence of an acid or an alkali. After completion of the reaction, a lower alcohol, a curing catalyst, a leveling agent and the like are further added as necessary. This is coated on a plastic substrate by dip, spray, bar coating, spin coating, or the like. After removing the solvent, generally 80-1
A film is formed by heating and curing in the range of 50 ° C. The curing temperature is preferably performed at a temperature equal to or lower than the thermal deformation temperature of the coated base plastic.

The siloxane resin thus formed can exhibit a hardness of several H to 9 H in pencil hardness. Hard coat resin, depending on the applied substrate material, for the purpose of improving the adhesion to the substrate surface, for example, surface treatment of the substrate surface with a silane compound called a silane coupling agent,
Or, it is common practice to modify the surface by a chemical or physical method to improve the adhesion.

An example of producing an electrophotographic photosensitive member having a protective layer according to the present invention will be described below.

As the support for the electrophotographic photosensitive member, any support can be used as long as it has conductivity. The support itself has conductivity, for example, aluminum, aluminum alloy, copper, zinc, and the like. Stainless steel, chrome, titanium, nickel, magnesium, indium,
In addition to gold, platinum, silver and iron, aluminum, indium oxide, tin oxide, gold and the like are formed on a dielectric support such as plastic by vapor deposition or the like to form a conductive layer,
What mixed conductive fine particles with plastic or paper can be used. For these supports, uniform conductivity is required and a smooth surface is important.

Since the surface smoothness greatly affects the uniformity of the undercoat layer, charge generation layer and charge transport layer formed thereon, the surface roughness is preferably 1.0 μm or less. Irregularities exceeding 1.0 μm change the local electric field applied to a thin layer such as an undercoat layer or a charge generation layer, so that the characteristics thereof greatly change, and defects such as charge injection and residual potential unevenness occur. Easy to occur.

In particular, a conductive layer obtained by dispersing and coating conductive fine particles in a polymer binder is easy to form, and is suitable for forming a uniform surface. The primary particle size of the conductive fine particles used at this time is preferably 100 nm or less, more preferably 50 nm.
The following are used: As the conductive fine particles, conductive zinc oxide, conductive titanium oxide, Al, Au, Cu, A
g, Co, Ni, Fe, carbon black, ITO, tin oxide, indium oxide, indium and the like are used,
These may be used by coating the surface of the insulating fine particles. The content of the conductive fine particles is used so that the volume resistance is sufficiently low, and is preferably 1 × 10 ¹⁰ Ωcm.
It is added so as to have the following resistance. More preferably 1
It is used at × 10 ⁸ Ωcm or less.

When exposure is performed using a coherent light source such as a laser, it is possible to form irregularities on the surface of the conductive support in order to prevent image deterioration due to interference. At this time, irregularities of about 1 / 2λ of the wavelength used are dispersed at a period of 10 μm or less by dispersing an insulator such as silica beads having a diameter of several μm or less so that defects such as charge injection and unevenness of residual potential do not easily occur. It can be formed and used.

An undercoat layer having an injection inhibiting function and an adhesive function can be provided between the conductive support and the photosensitive layer.
The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, polyamide, polyurethane, gelatin, or the like. The thickness of the undercoat layer is preferably 0.1 to 10 μm, more preferably 0.3 to 3 μm.

As the photosensitive layer, a function-separated type having a charge generation layer and a charge transport layer, or a single layer type in which charge generation and charge transport are performed in the same layer are used.

As the charge generation material, for example, selenium
Tellurium, pyrylium dye, thiopyrylium dye, phthalocyanine pigment, anthantrone pigment, dibenzopyrenequinone pigment, pyranthrone pigment, trisazo pigment, disazo pigment, azo pigment, indigo pigment, quinacridone pigment and Cyanine pigments and the like are used.

The charge transporting compound is roughly classified into an electron transporting compound and a hole transporting compound.

As the electron transporting compound, 2,4,7-
Examples thereof include electron accepting compounds such as trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, tetracyanoquinodimethane, and alkyl-substituted diphenoquinone, and those obtained by polymerizing these electron accepting compounds. .

Examples of the hole-transporting compound include polycyclic aromatic compounds such as pyrene and anthracene, carbazole, indole, oxazole, heterocyclic compounds such as thiazole, oxathiazole, pyrazole, pyrazoline, thiadiazole and triazole, and p-diethylaminobenzaldehyde. -N, N-diphenylhydrazone and N, N
Hydrazone-based compounds such as -diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-
4'-N, N-diphenylaminostilbene and 5-
(4- (di-p-tolylamino) benzylidene) -5H
-Styryl compounds such as dibenzo (a, d) cycloheptene, benzidine compounds and triarylamine compounds or polymer compounds having a group consisting of these compounds in the main chain or side chain (poly-N-vinylcarbazole, polyvinyl Anthracene).

Next, specific examples of the charge transporting compound are shown below.

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Embedded image As the charge generation material and the charge transporting compound, a binder polymer is used as necessary. Examples of the binder polymer include styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, polymers and copolymers of vinyl compounds such as vinylidene fluoride and trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, polycarbonate, Examples include polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin and the like.

In particular, as the polymer compound for the charge transport layer used in the present invention, a compound compatible with the charge transport compound is used. Representative polymer compounds include polyester, polycarbonate, polystyrene, polymethacrylate, and polyacrylate.

The charge transporting compound used in the charge transporting layer is preferably 20 to 70% by weight based on the solid content of the charge transporting layer. When the content is less than 20% by weight, sufficient charge transfer ability is hardly obtained, so that the residual potential is likely to increase. If it exceeds 70% by weight, the mechanical strength of the charge transport layer tends to decrease, so that it is difficult to obtain sufficient durability.

The amount of the polymer compound used in the charge transport layer is preferably 20 to 80% by weight based on the solid content of the charge transport layer. If it exceeds 80% by weight, it is difficult to obtain sufficient charge transfer ability, so that an increase in residual potential, a decrease in electrical durability, a reduction in the effect of lowering surface energy, and the like are likely to occur. If the amount is less than 20% by weight, the mechanical strength of the charge transport layer tends to decrease, so that it is difficult to obtain sufficient durability.

When used as a single-layer photoreceptor, good properties can be obtained by using a composition comprising a combination of the above-mentioned charge generating material, a charge transporting compound and a polymer compound.

Additives other than the above compounds can be used in the photosensitive layer in order to improve mechanical properties and durability. As such additives, an antioxidant, an ultraviolet absorber, a stabilizer, a crosslinking agent, a lubricant, a conductivity control agent, and the like are used.

On the photosensitive layer formed as described above, the above-mentioned protective layer used in the present invention is formed. The solvent used in the composition for forming the protective layer preferably does not attack the photosensitive layer, and is applied by a dip coating method, a blade coating method, a roll coating method, or the like. Even in the case where a solvent that attacks the photosensitive layer is used, the influence can be reduced by using the spray coating method.

Since the electrophotographic photoreceptor of the present invention has a high hardness and can form a uniform protective layer having good dispersibility of metal oxide fine particles, it has no image defects such as unevenness, fog and black spots, It has very high abrasion and environmental resistance, and also has excellent electrophotographic properties.

The electrophotographic photoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copiers, laser printers, LED printers, and liquid crystal shutter printers. , Plate making, facsimile, and the like.

Next, an electrophotographic image forming apparatus using the electrophotographic photosensitive member of the present invention will be described.

By forming a latent image on the electrophotographic photosensitive member of the present invention by charging and exposing the same, it was possible to always obtain a high-quality image with excellent durability. As a high-speed, low-noise printer, a laser beam printer adopting an electrophotographic system or a digital copying machine, a fax machine, and the like have a large effect of high image quality and high durability.

A laser beam printer employing an electrophotographic system or a digital copying machine, a facsimile, etc. is a binary recording in which images such as characters and figures are formed by applying or not applying a laser beam to a photosensitive member. In general, printing of characters and figures does not require halftones, so that the structure of the printer can be simplified.

However, there is a printer capable of expressing a halftone even with such a binary recording system. As such a printer, a printer employing a dither method, a density pattern method, or the like is well known. However, as is well known, high resolution cannot be obtained with a printer employing a dither method, a density pattern method, or the like. Therefore, in recent years, a method (PWM method) of forming a halftone in each pixel with high resolution without lowering the recording density has been proposed.

In this method, a halftone pixel is formed by modulating the time of irradiating a laser beam with an image signal. According to this method, a high-resolution and high-gradation image can be formed. In particular, a color image forming apparatus that requires high resolution and high gradation is particularly suitable. That is, according to this method, the area gradation of the dot formed by the beam spot can be performed for each pixel, and the halftone can be expressed without lowering the resolution.

However, even in this PWM method, if the pixel density is further increased, the pixels become relatively small with respect to the exposure spot diameter, so that it is not possible to sufficiently obtain gradation by exposure time modulation. There is.

Therefore, in order to improve the resolution while maintaining the gradation, it is necessary to make the exposure spot diameter smaller. For that purpose, for example, when using a scanning optical system using a laser, it is necessary to shorten the wavelength of the laser light, increase the NA of the f-θ lens, and the like. Due to the use of expensive lasers, the enlargement of lenses and scanners, and the increase in required mechanical precision due to the decrease in the depth of focus, it is inevitable that the apparatus will become larger and the cost will increase.

Further, even in solid-state scanners such as an LED array and a liquid crystal shutter array, an increase in the price of the scanner itself, an increase in mounting accuracy, and an increase in the cost of the electric drive circuit are inevitable.

Further, even when the light spot is miniaturized as described above, it is difficult to obtain good gradation reproducibility in the electrophotographic method, and the gradation is simulated by electrical processing. It was just reproducing.

In spite of the above-mentioned problems, the resolution and gradation required for the image forming apparatus using the electrophotographic method have been increasing more and more in recent years.

Under such circumstances, attempts have been made to improve the resolution and gradation by reducing the particle size of the toner used for development, and to improve the uniformity of the development conditions.

However, even if such an improvement is made, the reproducibility of gradation data such as full-color image data of 256 tones of 400 to 600 lines recognizable by the naked eye and the high resolution of binary images such as characters Reproduction was not enough.

As described above, an image which can be normally discriminated by the naked eye is about 400 dpi and about 256 gradations. In this case, the minimum resolution area is about 16 μm ² and 5000
This corresponds to a resolution higher than dpi. Further, in order to realize such high resolution, it is necessary to reduce the spot area of the light beam, but simply reducing the spot area has not been able to achieve the high image quality as described above.

In consideration of such a problem, in an electrophotographic image forming apparatus in which a latent image is formed by irradiating a light beam, the product of the film thickness of the photosensitive layer of the photosensitive member and the area of the irradiated spot is calculated. It has been found that there is a certain relationship between the tone reproducibility and that the product of the spot area and the film thickness of the photosensitive layer of the photoreceptor is 20,000 μm ³ or less, and 400 dpi,
It is possible to obtain extremely excellent image quality for realizing 256 gradations.

It is considered that this is because, in the conventional electrophotographic image forming apparatus, the conditions of the latent image formed on the photoreceptor and the development conditions are not sufficient despite the miniaturization of the light spot area. . That is, a phenomenon that image information given by a light spot is deteriorated due to diffusion of a photocarrier for forming a latent image while traveling through the photosensitive layer, and a potential potential contrast generated by the formed latent image. It is considered that a phenomenon occurs in which the image information provided by the light spot in the initial stage is greatly deteriorated due to the phenomenon that the image information is reduced due to the space existing up to the conductive support.

As described above, by setting the product of the spot area of the light beam and the thickness of the photosensitive layer of the photosensitive member to 20,000 μm ³ or less, it is possible to obtain a good image without causing the above-mentioned diffusion of carriers and a decrease in developability. It enables formation.

This is because the film thickness of the photosensitive layer of the photoreceptor used at the spot area obtained from the generally achievable minute light spot diameter, mainly the film thickness of the hole transport layer is 12 μm.
The following indicates that it is suitable.

As described above, it is desirable that the thickness of the photosensitive layer be thin. However, a thickness of 1 μm or more is desirable because pinholes and a decrease in sensitivity occur at the same charging potential. More preferably, it is used with a film thickness of 3 μm or more.

[0139]

The present invention will be described below in more detail with reference to specific examples.

FIG. 1 is a plan view showing a schematic cross-sectional view of the electrophotographic photosensitive member of the present invention.

The electrophotographic photoreceptor of the present invention has a protective layer on the surface. The protective layer composition is coated on the charge transport layer and dried by heating as shown in FIG. 1 (A). 1B, or by directly coating on the charge generation layer, as shown in FIG. 1B.

In order to perform high-resolution recording, the film thickness (L) of the charge transport layer and the resolution (S) of the recorded image shown in FIG.
It is necessary to increase the ratio (S / L), and if the ratio is small, the latent image is blurred due to the diffusion of the photocarrier,
Good images cannot be obtained. The ratio (S / L) is preferably 4 or more, and more preferably 5 or more.

In the process of visualizing a latent image formed on an electrophotographic photosensitive member with a developer, the potential potential contrast obtained is also affected by the above ratio. Similarly, it is preferable that the ratio is large, and it is required to reduce the thickness of the charge transport layer in order to improve the resolution.

At present, the required resolution is 400 dp.
i or more, more preferably 500 dpi or more, and the thickness of the charge transport layer used is 15 μm or less, more preferably 12 μm or less.

FIG. 2 shows an irradiation light intensity distribution and an irradiation light intensity distribution of the irradiation light reaching the conductive support in the electrophotographic image forming apparatus using the electrophotographic photosensitive member of the present invention.

[0146] The spot area of the light beam is represented by a portion until it decreases to 1 / e ² of the peak intensity.

The light beam used includes a scanning optical system using a semiconductor laser, and a solid-state scanner such as an LED or a liquid crystal shutter. The light intensity distribution also has a Gaussian distribution, a Lorentz distribution, and the like. The area up to 1 / e ² is the spot area. The light spot generally has an elliptical shape as shown in FIG.

The spot area of the light beam is 4000 μm ²
Used below. 400 dp over 4000 μm ²
When an image signal of i, 256 gradations is given, the influence of overlapping of adjacent pixels increases, and gradation reproducibility becomes unstable, which is not preferable.

The gradation reproducibility in the present invention is 400 dp.
When the irradiation amount of the light beam is linearly changed by 256 gradations at the resolution of i, the image density is defined by a portion proportional to the irradiation amount. FIG. 3 shows a schematic diagram of the measurement of gradation reproducibility in the present invention.

Image evaluation was performed using the image forming apparatus of the present invention.

A digital full-color copying machine and a laser beam printer were modified as the image forming apparatus of the present invention, and a semiconductor laser of 680 nm and 100 mW was used. The spot diameter on the photosensitive member was 400 lines at 1 / e ² in the sub-scanning direction. 1 / e ^{2 in the} main scanning direction, assuming a constant value of 63.5 μm.
The spot diameter was 20 μm, and the spot diameter was 25 μm.
An image was output after performing 6-level PWM modulation or pixel modulation equivalent to 600 dpi, and evaluated and measured. The spot area of the light spot is about 1000 μm ² . [Composition for Electrophotographic Photoreceptor Protective Layer] (Example 1 of liquid preparation) Colloidal silica (solid content 40
8.7 g of an aqueous dispersion of colloidal silica (solid content: 30% by weight), 25.6 g of methyltriethoxysilane, 2,3,4,4, 5,5,6,6,6-Nonafluorohexyltrimethoxysilane 5.9 g and acetic acid 3.2 g were added. After the addition, the mixed solution is 65-70.
C. and reacted for 2 hours. Thereafter, the mixture was diluted with 21.7 g of isopropyl alcohol, 2.4 g of benzyltrimethylammonium acetate was added as a curing catalyst, and 0.16 g of a 10% by weight ethanol solution of polyether-modified dimethyl silicone was added.

Next, 100 g of a solution obtained by diluting this solution with isopropyl alcohol so as to have a solid content of 30% by weight was obtained.
This solution was mixed with 30 g of surface treated antimony-containing tin oxide fine particles having an average particle diameter of 0.02 μm, further added with 90 g of isopropyl alcohol, and dispersed by a sand mill for 120 hours. Particles (Lubron L-2, manufactured by Daikin Industries, Ltd.) 20
g was mixed and further dispersed for 8 hours by a sand mill to obtain a dispersion liquid for a protective layer.

The above-mentioned method for treating the surface of the tin oxide fine particles was carried out as follows.

Antimony-containing tin oxide fine particles having an average particle size of 0.02 μm (T-1, manufactured by Mitsubishi Materials Corporation) 10
0 parts, 30 parts of (3,3,3-trifluoropropyl) trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), and 300 parts of a 95% by weight ethanol-5% by weight aqueous solution were mixed with a milling machine.
The solution that had been milled for an hour was filtered, washed with ethanol, dried, and subjected to a heat treatment at 120 ° C. for 1 hour to perform a surface treatment of the fine particles. (Preparation Example 2) Add colloidal silica (solid content 40)
3.9 g of an aqueous dispersion of 2% by weight of colloidal silica (solid content of 30% by weight), 26.8 g of isopropyl alcohol dispersion, 1.5 g of methyltriethoxysilane, γ-glycidoxypropyltri Methoxy sila 1.9g, 3,3,4,4,5,5,6,6,6-
2.4 g of nonafluorohexyltrimethoxysilane and 3.1 g of acetic acid were added. After the addition, the mixed solution was added to 65 to 7
The mixture was heated to 0 ° C. and reacted for 2 hours. Thereafter, the mixture was diluted with 23.3 g of isopropyl alcohol, 2.4 g of benzyltrimethylammonium acetate was added as a curing catalyst, and 0.16 g of a 10% by weight ethanol solution of polyether-modified dimethyl silicone was added.

Next, 100 g of a solution obtained by diluting this solution with isopropyl alcohol so as to have a solid content of 30% by weight was obtained.
This solution was mixed with 30 g of surface treated antimony-containing tin oxide fine particles having an average particle diameter of 0.02 μm, further added with 90 g of isopropyl alcohol, and dispersed by a sand mill for 120 hours. Particles (Lubron L-2, manufactured by Daikin Industries, Ltd.) 20
g was mixed and further dispersed for 8 hours by a sand mill to obtain a dispersion liquid for a protective layer.

The surface treatment of tin oxide followed the method of Preparation Example 1.

(Liquid Preparation Example 3) A flask was charged with 30.0 g of an aqueous dispersion of colloidal silica (solid content: 40% by weight).
While stirring, 1/3 of the whole mixture of 21.5 g of methyltrimethoxysilane and 3.5 g of acetic acid was added. After the addition, the mixed solution was heated to 55 ° C., and when a sudden heat generation was observed, the mixture was immediately cooled with ice, and the temperature in the flask was raised to 50 to 60 ° C.
And the remaining mixture was added. Reaction solution is 20
Cool to 0 ° C. and stir for 30 minutes when the temperature stabilizes. Thereafter, the reaction solution was diluted with 17.8 g of isopropyl alcohol, and 2.8 g of dibutyltin di-2-ethylhexoate was obtained.
Is gradually added, and benzyltrimethylammonium acetate and then polyether-modified dimethyl silicone are added.
0.16 g of a 0% by weight ethanol solution was added. The resulting reaction mixture was free of precipitate.

Next, 100 g of a solution obtained by diluting this solution with isopropyl alcohol to a solid content of 30% by weight was used.
This solution was mixed with 30 g of surface treated antimony-containing tin oxide fine particles having an average particle diameter of 0.02 μm, further added with 90 g of isopropyl alcohol, and dispersed by a sand mill for 120 hours. Particles (Rublon L-2, manufactured by Daikin Industries, Ltd.) 21
g was mixed and further dispersed for 8 hours by a sand mill to obtain a dispersion liquid for a protective layer.

The surface treatment of tin oxide followed the method of Preparation Example 1.

(Solution Example 4) 50 mol% of a methylsiloxane unit, 10 mol% of a dimethylsiloxane unit and 3,3,3
100 g of a 1% by weight silanol group-containing siloxane resin composed of 10 mol% of 4,4,5,5,6,6,6-nonafluorohexylsiloxane units is dissolved in 100 g of toluene, and 2 g of dibutyltin acetate is added thereto. The mixture was made into a homogeneous solution.

Next, 100 g of a solution obtained by diluting this solution with isopropyl alcohol to a solid content of 30% by weight was used.
Was prepared, and the average particle size of the primary particles was 0.0
30 g of 4 μm tin oxide fine particles were mixed, and 90 g of isopropyl alcohol was further added thereto and dispersed by a sand mill for 96 hours to obtain a coating liquid for a protective layer.

(Liquid Preparation Example 5) 4.1 g of an aqueous dispersion of colloidal silica (solid content: 40% by weight) was placed in a flask, and 26.5 g of an isopropyl alcohol dispersion of colloidal silica (solid content: 30% by weight) was stirred. , 1.8 g of methyltriethoxysilane, 2.4 g of γ-glycidoxypropyltrimethoxysilane, 1.1 g of n-perfluorooctylethyltriethoxysilane and 3.1 g of acetic acid. After the addition, the mixed solution is heated to 65 to 70 ° C.
Allowed to react for hours. Then, isopropyl alcohol 2
Diluted with 3.1 g, and dibutyltin di-2- as a curing catalyst
2.8 g of ethylhexoate was added, and 0.16 g of a 10% by weight solution of polyether-modified dimethyl silicone in ethanol was added.

Next, 100 g of a solution obtained by diluting this solution with isopropyl alcohol to a solid content of 30% by weight was used.
This solution was mixed with 20 g of antimony-containing tin oxide fine particles having an average particle size of 0.02 μm, and 90 g of isopropyl alcohol was further added thereto and dispersed in a sand mill for 120 hours. Particles (Lubron L-2, manufactured by Daikin Industries, Ltd.) 20
g was mixed and further dispersed for 8 hours by a sand mill to obtain a dispersion liquid for a protective layer.

The surface treatment of tin oxide followed the method of Preparation Example 1.

(Preparation Example 6) The amount of the tetrafluoroethylene resin particles in the dispersion for the protective layer used in Preparation Example 1 was set to 40 g.
Further, a dispersion for a protective layer was prepared in the same manner as in Preparation Example 1, except that the amount of the surface-treated antimony-containing tin oxide fine particles was changed to 40 g.

(Liquid Preparation Example 7) A protective layer dispersion was prepared in the same manner as in Liquid Preparation Example 3 except that the tin oxide fine particles used in the dispersion for the protective layer used in Liquid Preparation Example 3 were changed as follows. Prepared.

Antimony-containing tin oxide fine particles having an average particle size of 0.02 μm (T-1, manufactured by Mitsubishi Materials Corporation) 10
A solution obtained by milling 0 g, a fluorine-modified silicone oil (FL-100, manufactured by Shin-Etsu Chemical Co., Ltd.) 30 g and toluene 300 g for 1 hour with a milling machine was filtered, washed with toluene, dried, and dried at 300 ° C. for 10 minutes. The surface treatment of the fine particles was performed by performing a heat treatment.

(Liquid Preparation Example 8) Instead of the tetrafluoroethylene resin particles used in the dispersion for the protective layer used in Liquid Preparation Example 3, ethylene trifluoride chloride resin particles (Daiflon, manufactured by Daikin Industries, Ltd.) A dispersion for a protective layer was prepared in the same manner as in Preparation Example 3 except for using.

(Liquid Preparation Example 9) Barium sulfate fine particles coated with oxygen-deficient tin oxide instead of antimony-containing tin oxide fine particles used in the dispersion for the protective layer used in Liquid Preparation Example 3 had an average particle diameter of 0.01 μm. A dispersion liquid for a protective layer was prepared in the same manner as in Preparation Example 3 except that the conductive particles (Pastran IV / P-1, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used.

Example 1 An aluminum cylinder having an outer diameter of 30 mm formed by mirror polishing and having anodized aluminum formed by anodic oxidation was used as a conductive support.

Next, as a charge generating layer, 5 parts of the following bisazo pigment (parts by weight, the same applies hereinafter) was added to a solution prepared by dissolving 2 parts of polyvinyl benzal (a degree of benzalization of 75% by weight or more) in 95 parts of cyclohexanone. For 20 hours. This dispersion was applied on a conductive support by a dip coating method so that the film thickness after drying was 0.2 μm.

[0172]

Embedded image Next, 5 parts of a triarylamine compound having the following structural formula and 5 parts of a polycarbonate resin (trade name: Z-400, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were added to tetrahydrofuran 70
The liquid for the charge transport layer dissolved in the portion was dried on the charge generation layer by a dip coating method and then applied to a thickness of 10 μm.

[0173]

Embedded image Next, the composition for a photoreceptor protective layer of Preparation Example 1 was applied on the charge transport layer by a dip coating method, dried at 110 ° C. for 4 hours, and heat-treated to a thickness of 1.0 μm. The body was made. This photoreceptor was charged to -700 V, and electrophotographic characteristics were measured at a wavelength of 680 nm.
2 (exposure amount at which charging potential decreases to −350 V) = 1.
2 μJ / cm ² and a residual potential of 29 V were favorable.

Further, the composition for protective layer of Preparation Example 1 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured by a comb electrode was 5.9 × 10 ¹² Ωcm.

The electrophotographic photoreceptor was charged at an initial charge of −60 by an evaluation machine obtained by modifying a digital copying machine GP215 (roller charging system) manufactured by Canon to have the above-mentioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet copy durability test.
The tone reproducibility was as good as 256 tones at 400 dpi, and the abrasion of the photoreceptor was as small as 0.1 μm or less per 5,000 sheets of copy durability test. When the contact angle of water on the surface of the photoreceptor was measured, the initial contact angle was 94 degrees, and the contact angle was 5 degrees.
It was as good as 92 degrees even after the 000-sheet copy durability test.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images without unevenness or black spots were obtained. Was completed.

Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that an aluminum cylinder having an outer diameter of 80 mm formed by mirror finishing and having anodized aluminum was used as the conductive support. did.

The electrophotographic photoreceptor was initially charged by an evaluation machine obtained by modifying a digital copying machine CLC500 (a corona charging system) manufactured by Canon so as to have the aforementioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet copy durability test.
The gradation reproducibility was as good as 256 gradations at 400 dpi, and the abrasion loss of the photoreceptor was as extremely small as 0.1 μm or less per 5,000 sheets of copy durability test.

When the contact angle of water on the surface of the photoreceptor was measured, the initial contact angle was 94 ° and the contact angle was 92% even after the endurance test for 5000 sheets.
The degree was good.

Further, when a copy durability test was performed on 10,000 sheets, the protective layer did not peel off.

In order to measure the pause memory phenomenon,
After 10,000 sheets of durability, the photoconductor is left in the copying machine and
After a lapse of time, the potential difference ΔV between the surface potential of the photoreceptor located immediately below the corona charger and other portions was measured.
= 5V.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images without unevenness and black spots were obtained. Was completed.

(Example 3) A phenol resin (trade name: Plyofen, manufactured by Dainippon Ink and Chemicals, Inc.) was used as a conductive layer using an aluminum cylinder having an outer diameter of 30 mm obtained by drawing as a conductive support. 16
7 parts dissolved in 100 parts of methyl cellosolve, 200 parts of conductive barium sulfate ultrafine particles (primary particle diameter 50 nm) and 3 parts of silicone resin particles having an average particle diameter of 2 μm are dispersed and dried by dip coating. Film thickness of 1
Coating was performed so as to be 5 μm.

As an undercoat layer, alcohol-soluble copolymerized nylon (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.)
(5 parts) in 95 parts of methanol was applied by dip coating. After drying at 80 ° C. for 10 minutes, an undercoat layer having a thickness of 1 μm was formed.

Next, as a charge generation layer, 5 parts of an I-type titanyloxyphthalocyanine pigment was added to a solution prepared by dissolving 2 parts of polyvinyl benzal (a degree of benzalization of 75% by weight or more) in 95 parts of cyclohexanone, and dispersed by a sand mill for 2 hours. .

This dispersion was applied by dip coating on the undercoat layer formed previously so that the film thickness after drying was 0.2 μm.

Next, 5 parts of the triarylamine compound used in Example 1 and a polycarbonate resin (trade name: Z-4)
A solution for a charge transport layer, in which 5 parts of 00, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were dissolved in 70 parts of tetrahydrofuran, was dried on the charge generation layer by a dip coating method and then applied to a thickness of 10 μm. .

Next, the composition for a photoreceptor protective layer of Preparation Example 2 was applied on the above-mentioned charge transporting layer by dip coating, and dried and heat-treated at 110 ° C. for 4 hours.
An electrophotographic photoreceptor having a μm protective layer was obtained.

The above photoreceptor was charged to -700 V and the wavelength 6
When the electrophotographic characteristics were measured at 80 nm, E1 / 2
(Exposure amount at which charging potential decreases to −350 V) = 0.1
μJ / cm ² and a residual potential of −35 V were favorable.

The composition for protective layer of Preparation Example 2 was applied on a glass substrate by using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured with a comb-shaped electrode was 4.8 × 10 ¹² Ωcm.

The electrophotographic photoreceptor was charged at an initial charge of −60 by an evaluation machine in which a digital copying machine GP215 (roller charging system) manufactured by Canon was modified to have the above-mentioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet durability test, and the tone reproducibility was as good as 256 tones at 400 dpi. The amount of abrasion was as small as 0.1 μm per 5,000 durability tests. When the contact angle of water on the surface of the photoreceptor was measured, the initial angle was 95 degrees, which was as good as 91 degrees after the 5,000-sheet durability test.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images free from unevenness and black spots were obtained. Was completed.

(Comparative Example 1) An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the coating solution of Preparation Example 4 was used as a protective layer.

Further, the composition for protective layer of Preparation Example 4 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 3 μm was obtained. The volume resistance of this sample measured by a comb electrode was 2.9 × 10 ¹² Ωcm.

Example 1 This electrophotographic photoreceptor was manufactured using a digital copying machine GP215 (roller charging system) manufactured by Canon.
When the same evaluation was performed, interference fringes and black spots were recognized in the initial stage, and streaks were observed in the image after the durability test of 5000 sheets. Photoreceptor wear is 500
After the endurance test of 0 sheets, it was greatly shaved to 3 μm. Also,
When the contact angle of water on the surface of the photoreceptor was measured, it was found to be 94 degrees at the initial stage and slightly decreased to 88 degrees after the 5000 sheet durability test.

When the above-mentioned copying machine was subjected to image evaluation under low temperature and low humidity of 10 ° C. and 15% and under high temperature and high humidity of 35 ° C. and 85%, occurrence of unevenness and black spots was recognized.

(Example 4) A phenol resin (trade name: Plyofen, manufactured by Dainippon Ink and Chemicals, Inc.) was used as a conductive layer using an aluminum cylinder having an outer diameter of 30 mm obtained by drawing as a conductive support. 16
7 parts dissolved in 100 parts of methyl cellosolve, 200 parts of conductive barium sulfate ultrafine particles (primary particle diameter 50 nm) and 3 parts of silicone resin particles having an average particle diameter of 2 μm are dispersed and dried by dip coating. Film thickness of 1
Coating was performed so as to be 5 μm.

As an undercoat layer, alcohol-soluble copolymerized nylon (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.)
(5 parts) in 95 parts of methanol was applied by dip coating. After drying at 80 ° C. for 10 minutes, an undercoat layer having a thickness of 1 μm was formed.

Next, as a charge generation layer, 5 parts of an I-type titanyloxyphthalocyanine pigment was added to a solution of 2 parts of polyvinyl benzal (a degree of benzalization of 75% by weight or more) dissolved in 95 parts of cyclohexanone, and dispersed by a sand mill for 2 hours. .

This dispersion was applied by dip coating on the previously formed undercoat layer so that the film thickness after drying was 0.2 μm.

Next, 5 parts of the triarylamine compound used in Example 1 and a polycarbonate resin (trade name: Z-40)
0, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 5 parts in a solution of 70 parts of tetrahydrofuran, a solution for a charge transport layer was dried on the charge generation layer by a dip coating method, and then applied to a thickness of 10 μm. .

Next, the composition for a photoreceptor protective layer of Preparation Example 3 was applied on the above-mentioned charge transporting layer by dip coating, and dried and heat-treated at 110 ° C. for 4 hours.
An electrophotographic photoreceptor having a μm protective layer was obtained.

When the electrophotographic photoreceptor of the present invention was charged to -700 V and the electrophotographic characteristics were measured at a wavelength of 680 nm, E1 / 2 (exposure amount at which the charged potential decreased to -350 V) = 0.1 μJ / cm ^2. And the residual potential was 50 V, which was good.

The composition for protective layer of Preparation Example 4 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 3 μm was obtained. The volume resistance of this sample measured with a comb-shaped electrode was 7.6 × 10 ¹² Ωcm.

The image of the electrophotographic photosensitive member was evaluated at an initial charge of -500 V using a modified machine of a laser beam printer (LBP-8 Mark IV) manufactured by Canon Inc. (modified to the irradiation spot conditions described above, using an AC roller charger). However, the wear amount of the photoconductor after the durability test of 4000 sheets was 0.1%.
μm or less, the contact angle of water after endurance is 96
The degree of reproducibility was satisfactory, the image was not deteriorated, and the reproducibility of one pixel of a highlight portion in an input signal equivalent to 600 dpi was sufficient. (Comparative Example 2) An electrophotographic photosensitive member was prepared in the same manner as in Example 3 except that the protective layer was not provided, and evaluation was performed in the same manner as in Example 3. As a result, an image output having excellent uniformity can be obtained in the initial stage, similarly to the third embodiment.
The tone reproducibility was as good as 256 tones at 400 dpi. However, when a copy durability test was performed, the abrasion loss of the photoreceptor was as large as 4 μm per the durability test of 5000 sheets.
Gradual decrease in charging ability was observed. When the contact angle of water on the surface of the photoreceptor was measured, the initial contact angle was 87 degrees and the contact angle was 50 degrees.
Even after the endurance test of 00 sheets, the temperature was reduced to 65 degrees, and after the endurance test, a part of the toner was fused to the surface of the photoreceptor.

(Example 5) Using an aluminum cylinder having an outer diameter of 30 mm obtained by drawing, 167 parts of a phenol resin (trade name: Plyofen, manufactured by Dainippon Ink and Chemicals, Inc.) was used as a conductive layer in methyl cellosolve. 200 parts of conductive barium sulfate ultrafine particles (primary particle diameter: 50 nm) and an average particle diameter of 2 μm were dissolved in 100 parts.
A dispersion obtained by dispersing 3 parts of the above silicone resin particles was applied by a dip coating method so that the film thickness after drying was 15 μm.

As an undercoat layer, alcohol-soluble copolymerized nylon (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.)
(5 parts) in 95 parts of methanol was applied by dip coating. After drying at 80 ° C. for 10 minutes, an undercoat layer having a thickness of 1 μm was formed.

Next, 5 parts of an oxytitanium phthalocyanine pigment was added to 95 parts of cyclohexanone as a charge generating layer in polyvinyl benzal (a degree of benzalization of 75% by weight or more).
Two parts were added to the dissolved solution, and dispersed in a sand mill for 2 hours.

This dispersion was applied by dip coating on the undercoat layer formed previously so that the film thickness after drying was 0.2 μm.

Next, 5 parts of the triarylamine compound used in Example 1 and a polycarbonate resin (trade name: Z-40)
0, 5 parts of Mitsubishi Gas Chemical Co., Ltd.) dissolved in 70 parts of tetrahydrofuran, a solution for the charge transport layer was dried on the charge generation layer by a dip coating method, and then applied to a thickness of 11 μm. .

Next, the composition of Preparation Example 5 was applied onto the charge transport layer by a dip coating method.
After a drying heat treatment for an hour, an electrophotographic photoreceptor having a thickness of 1.5 μm was prepared.

This photoreceptor was charged to -700 V, and a wavelength of 6
When the electrophotographic characteristics were measured at 80 nm, E1 / 2
(Exposure amount at which charging potential decreases to −350 V) = 0.1
1 μJ / cm ² and a residual potential of 40 V were favorable.

Further, the composition for protective layer of Preparation Example 5 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 3 μm was obtained. The volume resistance of this sample measured with a comb-shaped electrode was 6.2 × 10 ¹² Ωcm.

The electrophotographic photoreceptor was initially charged by a remodeling machine of a laser beam printer P270 manufactured by Canon Inc. (reforming to the irradiation spot conditions described above, using an AC roller charger).
When the image was evaluated at 500 V, the abrasion amount of the photoreceptor after the durability test of 4000 sheets was as extremely small as 0.2 μm, the contact angle of water after the durability test was 98 degrees, and the image was not deteriorated. However, the reproducibility of one pixel in a highlight portion in an input signal equivalent to 600 dpi was slightly insufficient.

Example 6 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the dispersion of Preparation Example 6 was used instead of the dispersion for the protective layer used in Example 1.

This photoreceptor was charged to -700 V, and a wavelength of 6
When the electrophotographic characteristics were measured at 80 nm, E1 / 2 (-
Exposure amount at which charging potential decreases to 350 V) = 1.2 μJ
/ Cm ² and a residual potential of 29 V.

Further, the composition for protective layer of Preparation Example 6 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured by a comb electrode was 5.9 × 10 ¹¹ Ωcm.

The electrophotographic photoreceptor was charged at an initial charge of −60 by an evaluation machine obtained by modifying a digital copying machine GP215 (roller charging system) manufactured by Canon to have the above-mentioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet copy durability test.
The gradation reproducibility was as good as 256 gradations at 400 dpi, and the abrasion amount of the photoreceptor was as small as 0.3 μm per 5,000-sheet copy durability test. When the contact angle of water on the surface of the photoreceptor was measured, the initial contact angle was 98 degrees and the contact angle was 500 degrees.
It was as good as 93 degrees even after the zero-sheet copy durability test.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15%, and under high-temperature and high-humidity conditions of 35 ° C. and 85%, it was found that there was no unevenness or black spots due to missing holes. Images were obtained.

Example 7 An electrophotographic photosensitive member was produced in the same manner as in Example 2, except that the dispersion of Preparation Example 7 was used instead of the dispersion for the protective layer used in Example 2.

This photoreceptor was charged to -700 V, and a wavelength of 6
When the electrophotographic characteristics were measured at 80 nm, E1 / 2 (-
Exposure amount at which charging potential decreases to 350 V) = 1.2 μJ
/ Cm ² and a residual potential of 38 V.

Further, the composition for protective layer of Preparation Example 7 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured by a comb electrode was 6.8 × 10 ¹² Ωcm.

This electrophotographic photoreceptor was initially charged with a digital copying machine CLC500 (a corona charging method) manufactured by Canon and modified so as to have the aforementioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet copy durability test.
The gradation reproducibility was as good as 256 gradations at 400 dpi, and the abrasion loss of the photoreceptor was as extremely small as 0.1 μm or less per 5,000 sheets of copy durability test.

When the contact angle of water on the surface of the photoreceptor was measured, the initial value was 92 degrees, which was as good as 90 degrees after the 5,000-sheet copy durability test.

Further, when a copy durability test was performed on 10,000 sheets, the protective layer did not peel off.

For measuring the pause memory phenomenon,
After 10,000 sheets of durability, the photoconductor is left in the copying machine and
After a lapse of time, the potential difference ΔV between the surface potential of the photoreceptor located immediately below the corona charger and other portions was measured.
= 5V.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images free from unevenness and black spots were obtained. Was completed.

Example 8 An electrophotographic photosensitive member was prepared in the same manner as in Example 2, except that the dispersion of Preparation Example 8 was used instead of the dispersion for the protective layer used in Example 3.

The above photoreceptor was charged to -700 V, and a wavelength of 6
When the electrophotographic characteristics were measured at 80 nm, E1 / 2
(Exposure amount at which charging potential decreases to −350 V) = 0.1
μJ / cm ² and residual potential of 40 V were favorable.

Further, the composition for a protective layer of Preparation Example 8 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured with a comb-shaped electrode was 1.5 × 10 ¹³ Ωcm.

The electrophotographic photoreceptor was initially charged at −60 by an evaluation machine in which a digital copying machine GP215 (roller charging system) manufactured by Canon was modified to have the aforementioned irradiation spot diameter.
When the image was evaluated at 0 V, an image output with excellent uniformity was obtained at the initial stage and after the 5,000-sheet durability test, and the tone reproducibility was as good as 256 tones at 400 dpi. The amount of abrasion was as small as 0.1 μm per 5,000 durability tests. When the contact angle of water on the surface of the photoreceptor was measured, it was as good as 90 degrees even after the endurance test for 5000 sheets, compared with 95 degrees at the beginning.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images free from unevenness and black spots were obtained. Was completed.

Example 9 An electrophotographic photosensitive member was prepared in the same manner as in Example 4, except that the dispersion of Preparation Example 9 was used instead of the dispersion for the protective layer used in Example 4.

When the electrophotographic photoreceptor of the present invention was charged to -700 V and the electrophotographic characteristics were measured at a wavelength of 680 nm, E1 / 2 (exposure amount at which the charging potential decreased to -350 V) = 0.1 μJ / cm ^2. And the residual potential was 68 V, which was good.

Further, the composition for protective layer of Preparation Example 9 was applied on a glass substrate using a bar coat, and dried and heat-treated at 110 ° C. for 4 hours. After drying, a transparent and uniform film of 2 μm was obtained. The volume resistance of this sample measured with a comb-shaped electrode was 7.1 × 10 ¹³ Ωcm.

The electrophotographic photoreceptor was subjected to image evaluation at an initial charge of -500 V using a modified machine of a laser beam printer (LBP-8Mark IV) manufactured by Canon Inc. (modified to the irradiation spot conditions described above, using an AC roller charger). However, the wear amount of the photoconductor after the durability test of 4000 sheets was 0.1%.
μm or less, water contact angle after durability is 92
The degree of reproducibility was satisfactory, the image was not deteriorated, and the reproducibility of one pixel of a highlight portion in an input signal equivalent to 600 dpi was sufficient.

When the above-mentioned copying machine was evaluated under low-temperature and low-humidity conditions of 10 ° C. and 15% and under high-temperature and high-humidity conditions of 35 ° C. and 85%, good images without unevenness and black spots were obtained. Was completed. Next, an image forming apparatus according to an embodiment of the present invention will be briefly described with reference to FIG.

First, the document G is set on the document table 10 with the surface to be copied facing downward. Next, copying is started by pressing the copy button. A unit 9 in which a document irradiation lamp, a short focus lens array and a CCD sensor are integrated.
Scans while irradiating the original, the illuminated scanning light is imaged by the short focus lens array and
It is incident on the sensor. The CCD sensor includes a light receiving unit, a transfer unit, and an output unit. The optical signal is converted into an electric signal in the CCD light receiving unit, and is sequentially transferred to the output unit in synchronization with the clock pulse in the transfer unit. The output unit converts the charge signal into a voltage signal, amplifies the voltage signal, reduces the impedance, and outputs the signal. The analog signal obtained in this way is converted into a digital signal, and further converted into a digital signal for performing image processing for optimizing the resolution and gradation according to the characteristics of the image and outputting the digital signal. Sent to the department. When outputting from a computer or the like, resolution, gradation reproduction method and the like are selected, processed and converted so as to obtain a desired image, and sent to a printer unit. The printer unit receives the image signal and forms an electrostatic latent image as follows. The photosensitive drum 1 of the present invention is driven to rotate around a center support shaft at a predetermined peripheral speed, and receives a uniform positive or negative charging process of a predetermined voltage by a charger 3 during the rotation process. By scanning the light of the solid-state laser element, which emits light on and off in response to the image signal, on a uniformly charged surface by a rotating polygon mirror rotating at high speed, an electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive drum 1 Images are formed sequentially.

FIG. 5 shows a schematic mechanism of a laser scanning unit 300 (100 in FIG. 4) for scanning a laser beam in the above-described apparatus.

When the laser beam is scanned by the laser scanning section 300, first, the solid-state laser element 30 is emitted by the light emission signal generator 301 based on the input image signal.
The laser light emitted from 2 is converted into a substantially parallel light beam by a collimator lens system 303, and further scanned in a direction of an arrow c by a rotating polygon mirror 304 rotating in a direction of an arrow b, and fθ lens groups 305a, 305b and 3
05c forms a spot-like image on the scanned surface 306 such as a photosensitive drum.

An exposure distribution for one scan of an image is formed on the surface to be scanned 306 by such scanning of the laser beam, and by scrolling the surface to be scanned 306 by a predetermined amount perpendicular to the scanning direction, An exposure distribution according to the image signal is obtained on the scanned surface 306.

In this embodiment, since the multi-level recording based on the area gradation of one pixel is performed by using the laser PWM method (pulse width modulation), the PWM method will be briefly described. FIG. 6 is a circuit block diagram showing one example of the pulse width modulation circuit, and FIG. 7 is a timing chart showing the operation of the pulse width modulation circuit.

In FIG. 6, reference numeral 401 denotes a TTL latch circuit for latching an 8-bit digital image signal;
A high-speed level converter 403 for converting the L logic level to the ECL logic level, and a high-speed D / A converter 403 for converting the ECL logic level to an analog signal. 404 is PWM
ECL comparator for generating signal, 405 is ECL comparator
A level converter for converting the logic level to a TTL logic level, a clock oscillator 406 for oscillating the clock signal 2f, a reference numeral 407 for generating a substantially ideal triangular wave signal in synchronization with the clock signal 2f, and a reference numeral 408 for the clock signal 2f Is a 分 frequency divider that generates the image clock signal f by dividing the frequency by １ ／. Thus, the clock signal 2f has a cycle twice as long as the image clock signal f. In order to operate the circuit at high speed, ECL is used everywhere.
A logic circuit is provided.

The operation of the circuit having the above configuration will be described with reference to the timing chart of FIG. The signal (a) shows the clock signal 2f and the signal (b) shows the image clock signal f, which are related to the image signal as shown in the figure. Also, inside the triangular wave generator, the clock signal 2f is once frequency-divided by か ら to generate the triangular wave signal (c) in order to keep the duty ratio of the triangular wave signal at 50%. Further, this triangular wave signal (c) is converted into an ECL level to become a triangular wave signal (d).

On the other hand, the image signal is from 00h (white) to FFh
It changes at 256 gradation levels up to (black). The symbol 'h' indicates hexadecimal notation. And the image signal (e) is D / A for some image signal values.
The converted ECL voltage level is shown. For example, the first
The pixel indicates a black pixel level FFh, the second pixel indicates a halftone level 80h, the third pixel indicates a halftone level 40h, and the fourth pixel indicates a halftone level 20h. The comparator generates a PWM signal having a pulse width T, t ₂ , t ₃ , t ₄ or the like corresponding to the pixel density to be formed by comparing the triangular wave signal (d) with the image signal (e). Then, this PWM signal is converted into a TTL level of 0 V or 5 V, becomes a PWM signal (f), and is input to the laser driver circuit. By changing the exposure time per pixel corresponding to the PWM signal value obtained in this way, it is possible to obtain a maximum of 256 gradations per pixel.

In this embodiment, the gradation control by the PWM method is used. However, an area gradation method such as a dither method or laser light intensity modulation can be used, and furthermore, these methods may be combined.

In this way, the electrostatic latent image formed on the photosensitive drum 1 of FIG. 4 is developed by the developing device 4, and the formed toner image is electrostatically transferred onto a transfer material by the transfer charger 7. You. Thereafter, the transfer material is electrostatically separated by the separation charger 8, conveyed to the fixing device 6, and thermally fixed to output an image. Reference numeral 2 denotes a charge exposing unit.

On the other hand, the surface of the photosensitive drum 1 after the transfer of the toner image is subjected to removal of adhered contaminants such as untransferred toner by the cleaner 5 and is repeatedly used for image formation.

FIG. 8 is a schematic view of a color copying machine according to the present invention.

Referring to FIG. 8, reference numeral 201 denotes an image scanner, which reads a document and performs digital signal processing. Reference numeral 200 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner 201 on a sheet in full color.

In the image scanner section 201, 20
Reference numeral 2 denotes an original plate, and an original platen glass (hereinafter, platen) 2
This is used to fix the original 204 on the document 03. The document 204 is irradiated with light from a halogen lamp 205. The reflected light from the document 204 is guided to mirrors 206 and 207, and a three-line sensor (hereinafter referred to as a CCD) 21 composed of three CCD line sensors by a lens 208.
Form an image on 0. The CCD 210 separates the light information from the document into colors and sends it to the signal processing unit 209 as red (R), green (G), and blue (B) components of the full color information. Note that 205 and 206 are speeds v, and 207 is ｖ v by mechanically moving the line sensor in a direction perpendicular to an electrical scanning direction (hereinafter, main scanning direction) (hereinafter, sub-scanning direction). Scans the entire original.

Reference numeral 211 denotes a standard white plate for generating data for correcting read data corresponding to the R, G, and B component line sensors at the time of shading correction. Used.

The standard white plate has a substantially uniform reflection characteristic with respect to visible light. Using this standard white plate,
It is used for correcting output data of the G and B visible sensors 210-2 to 210-4.

In the signal processing unit 209, the read signal is electrically processed, decomposed into magenta (M), cyan (C), yellow (Y), and black (BK) components, and sent to the printer unit 200. . Also, the image scanner unit 20
1 for one original scan (scan), M,
One component of C, Y, and BK is sent to the printer 200 in a frame-sequential manner, and one color image formation is completed by a total of four document scans.

The M, C, Y, and BK image signals sent from the image scanner unit 201 are transmitted to the laser driver 2.
12 is sent. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. The laser beam scans on the photosensitive drum 217 via the polygon mirror 214, the f-θ lens 215, and the mirror 216.

Reference numerals 219 to 222 denote developing units, which are a magenta developing unit 219, a cyan developing unit 220, and a yellow developing unit 2
21; a black developing device 222; four developing devices alternately contact the photosensitive drum, and develop M, C, Y, and BK electrostatic latent images formed on the photosensitive drum 217 with corresponding toners; I do.

Reference numeral 223 denotes a transfer drum.
4 or 225 to the transfer drum 2
23, and the toner image developed on the photosensitive drum 217 is transferred to a sheet. Thus, M, C, Y, B
After the four colors K are sequentially transferred, the sheet is fixed to the fixing unit 2.
After passing through 26 and being fixed, the sheet is discharged.

The above-described electrophotographic image forming apparatus uses a semiconductor laser to expose a photosensitive member by a polygonal scanning optical system. However, an LED printer is used as a solid-state scanner having no mechanical driving unit such as a polygon. A head is used. The LED printer head is one in which light-emitting diodes are integrated in a substantially linear shape, and one having a high resolution of 400 dpi or more is also produced. Since there is no driving part, it is advantageous for miniaturization. The spot light from the LED printer head is imaged on the photoreceptor by the converging rod lens array. At this time, the resolution in the main scanning direction is LE
400d, determined by the degree of integration of the D printer head
The resolution is higher than pi, that is, 63.5 μm, but the sub-scanning direction is determined by the light-collecting performance of the rod lens array and the moving speed of the photoconductor.

Although the light emission intensity distribution of the LED has a more rectangular distribution than the Gaussian distribution, the area of a portion having 1 / e ² of the peak intensity may be considered.

[0260]

As described above, a composition containing colloidal silica and siloxane resin, and further containing conductive particles and fluorine atom-containing resin particles surface-treated with a fluorine atom-containing compound is used as a surface protective layer. Electrophotography with excellent wear resistance due to little deterioration due to discharge, low contamination due to low surface energy, excellent cleaning properties, and excellent electrical properties such as environmental stability of charging and residual potential. Photoconductor was realized.

Further, since the electrophotographic photosensitive member has little light scattering, the electrophotographic image forming apparatus using the same can not only have excellent durability but also provide a good image after the durability. did. In particular, in a digital electrophotographic image forming apparatus using a spot light such as a laser beam, it is possible to reduce the thickness of the photosensitive layer while maintaining the durability, so that the photosensitive layer has a high resolution of 400 dpi.
It has become possible to obtain an even and high-quality image output having excellent gradation reproducibility of 56 gradations.

[Brief description of the drawings]

FIG. 1A is an electrophotographic photoreceptor of the present invention in which a composition containing colloidal silica and a siloxane resin and containing conductive particles and fluorine atom-containing resin particles is used for a surface protective layer of a charge transport layer. FIG. 1B is a schematic view of a cross section of (B), wherein the composition containing colloidal silica and a siloxane resin and containing conductive particles and fluorine atom-containing resin particles is used for a surface protective layer of a charge generation layer according to the present invention. FIG. 2 is a schematic view of a cross section of the electrophotographic photosensitive member.

FIG. 2 is a schematic diagram showing a spot shape of an irradiation light beam and an intensity distribution of the light beam reaching a conductive support in the electrophotographic photosensitive member of the present invention.

FIG. 3 is a schematic diagram showing a relationship between a light irradiation amount and an image density in a method of measuring gradation reproducibility.

FIG. 4 is a schematic view of an electrophotographic image forming apparatus of the present invention.

FIG. 5 is a schematic diagram of a laser beam scanning unit of the present invention.

FIG. 6 is a circuit block diagram of a pulse width modulation circuit for controlling laser light according to the present invention.

FIG. 7 is a timing chart showing an operation of a pulse width modulation circuit for controlling laser light according to the present invention.

FIG. 8 is a configuration diagram of a color copying machine of the electrophotographic image forming apparatus of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masataka Kawahara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor ▲ Taka ▼ Tani, 3--30-2 Shimomaruko, Ota-ku, Tokyo No. Within Canon Inc. (72) Inventor ▲ Yoshi ▼ Kazuo Naga Within 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (15)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer and a protective layer on a support, wherein the protective layer contains colloidal silica and a siloxane resin, and the conductive particles and the fluorine are surface-treated with a fluorine atom-containing compound. An electrophotographic photoreceptor containing atom-containing resin particles. 2. The fluorine atom-containing compound is selected from the group consisting of a fluorine-containing silane coupling agent, a fluorine-modified silicone oil and a fluorine-based surfactant.
The electrophotographic photosensitive member according to the above. 3. The electrophotographic photoreceptor according to claim 1, wherein said fluorine atom-containing resin particles are selected from the group consisting of ethylene tetrafluoride resin and vinylidene fluoride resin. 4. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a charge generation layer and a charge transport layer. 5. The electrophotographic photosensitive member according to claim 1, wherein said photosensitive layer has a thickness of 12 μm or less. Wherein said protective layer is fused in the presence of colloidal silica, the following formula _{(I) RSiO 3/2 (I)} ( wherein, R is an alkyl group having 1 to 3 carbon atoms, vinyl groups, C
_{n F 2n + 1 C 2 H} 4 - group (n = 1~18), representing the γ- glycidoxypropyl group and γ- methacryloxypropyl least one group selected from the group consisting of propyl group. 6. The electrophotographic photoreceptor according to claim 1, further comprising a compound represented by the formula: 7. The electrophotographic photosensitive member according to claim 1, wherein said conductive particles are made of a metal oxide. 8. The protective layer has a volume resistance of 1 × 10 ⁹ to 1
The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the electrophotographic photoreceptor has a density of × 10 ¹⁵ Ωcm. 9. The protective layer has a thickness of 0.2 to 3.0 μm.
The electrophotographic photoreceptor according to any one of claims 1 to 8, wherein 10. An electrophotographic image forming apparatus which forms a latent image on an electrophotographic photosensitive member by exposure and develops the formed latent image to obtain an image, wherein the image forming apparatus charges the photosensitive member. 2. An electrophotographic image forming apparatus, comprising: an electrophotographic photoconductor according to claim 1, further comprising a developing unit and a developing unit for developing the obtained latent image with toner. 11. An electrophotographic image forming apparatus for forming a latent image by irradiating a light beam modulated by an input signal onto an electrophotographic photosensitive member and scanning the electrophotographic photosensitive member, and developing the formed latent image to obtain an image. In the apparatus, the image forming apparatus comprises:
Means for controlling the exposure amount of the light beam to the photoconductor according to the resolution and gradation of the image to be recorded, means for charging the photoconductor, and means for developing the obtained latent image with toner, An electrophotographic image forming apparatus, wherein the photoconductor is the electrophotographic photoconductor according to claim 1. 12. The product of the spot area of the light beam and the thickness of the photosensitive layer is 20,000 μm ³ or less.
An electrophotographic image forming apparatus as described in the above. 13. An electrophotographic image forming apparatus according to claim 11, wherein said means for controlling the amount of exposure includes exposure time modulation. 14. An electrophotographic image forming apparatus according to claim 11, wherein said light beam is obtained by a semiconductor laser. 15. An electrophotographic image forming apparatus according to claim 11, wherein said light beam is obtained by an LED array.