JP2003316059A - Electrophotographic photoreceptor, and process cartridge and electrophotographic device having electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which not only prevents decrease in the image density from the initial stage at low humidity, changes in the density with time, and image defects such as image flow and ghost images at high humidity but can stably produce high-quality images without depending on the environment for repeated use by reducing environmental fluctuation in the resistance of a protective layer without subjecting conductive particles to surface treatment, and to provide a process cartridge and an electrophotographic device having the electrophotographic photoreceptor. <P>SOLUTION: In the electrophotographic photoreceptor having a supporting body, a photosensitive layer on the supporting body and a protective layer on the photosensitive layer, the protective layer contains resin and tin oxide particles doped with a tungsten element. The process cartridge and the electrophotographic device have the electrophotographic photoreceptor. <P>COPYRIGHT: (C)2004,JPO

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, and more particularly to an electrophotographic photosensitive member having a protective layer.
The present invention also relates to a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Electrostatic or mechanical external forces such as charging, exposure, development, transfer and cleaning are directly applied to the surface of an electrophotographic photosensitive member, and therefore durability against them is required. Specifically, durability against wear and scratches on the surface of the photoconductor due to contact with toner, paper, cleaning member, etc., and deterioration of the surface of the photoconductor due to adhesion of active substances such as ozone and NOx generated during charging. Is required.

Attempts have been made to provide various protective layers in order to satisfy the above-mentioned characteristics required for electrophotographic photoreceptors. Above all, many protective layers containing a resin as a main component have been proposed. For example, JP-A-57-30846 proposes a surface protective layer containing a resin and conductive metal oxide particles. Then, as a metal oxide that can be used for such a protective layer, that is, as conductive particles, zinc oxide or tin oxide doped with titanium oxide has been proposed.

[0004]

Generally, the resistance of a protective layer containing a binder resin and conductive particles such as tin oxide doped with zinc oxide or titanium oxide, or indium oxide doped with tin oxide is It tends to be high under low humidity and low under high humidity. In a process cartridge or an electrophotographic apparatus equipped with an electrophotographic photosensitive member having such a protective layer, a low image density or a change in durable density may occur under low humidity, and image defects such as image deletion or ghost may occur under high humidity. Become. In particular, image deletion or positive ghost is likely to occur due to deterioration of charging property under high humidity. In order to suppress such environmental changes in resistance of the protective layer, a method of subjecting the conductive particles to a surface treatment is known. However, in order to carry out the surface treatment, it is not only necessary to increase some manufacturing steps, but also it is difficult to stabilize the actual treatment amount after the surface treatment and there is a problem that strict process control is required. It is desired to suppress environmental fluctuations in the resistance of the protective layer without subjecting the conductive particles to a surface treatment.

An object of the present invention is to reduce the environmental fluctuation of the resistance of the protective layer in an electrophotographic photoreceptor having a protective layer containing conductive particles and a binder resin without subjecting the conductive particles to a surface treatment. Is.

Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having an electrophotographic photosensitive member having the protective layer, in which the image density is low and the durable density is changed from the initial stage under low humidity, and under high humidity. It is an object of the present invention to provide a process cartridge and an electrophotographic apparatus which are free from image defects such as image deletion and ghost, and which can stably obtain a high-quality image regardless of the environment during repeated use.

[0007]

That is, the present invention provides an electrophotographic photoreceptor having a support, a photosensitive layer on the support and a protective layer on the photosensitive layer, wherein the protective layer is doped with elemental tungsten. An electrophotographic photosensitive member comprising tin oxide particles and a resin.

The present invention also provides a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

The present invention also provides a process cartridge and an electrophotographic apparatus provided with the electrophotographic photosensitive member and a charging means using charged particles whose main component is electrically conductive particles having a small particle diameter and having specific physical properties. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Tin oxide doped with elemental tungsten is a general conductive particle having excellent conductivity. The amount of tungsten element doped is preferably 0.01 to 40 mol%, more preferably 1 to 30 mol%, and most preferably 1 to 2 with respect to tin oxide.
It is in the range of 0 mol%. When the content of the elemental tungsten is less than the above range, excellent conductivity is difficult to obtain, which is not preferable, and when it is more than the above range, improvement in conductivity is difficult to be recognized, which is not preferable. The conductive tin oxide contained in the protective layer of the present invention is in the form of fine particles, and preferably has a specific surface area of 5 to 200 m ² / g, more preferably 10 to 200 m ² / g, and most preferably. Is in the range of 30 to 100 m ² / g. If the specific surface area of the conductive tin oxide is smaller than the above range, it is not preferable because the transparency and smoothness when formed into a coating film is likely to decrease, and if it is larger than the above range, poor dispersion tends to occur during coating, which is not preferable. .

When tin oxide doped with elemental tungsten is used as the conductive particles contained in the protective layer of an electrophotographic photoreceptor as in the present invention, the resistance of tin oxide after doping is 1 × 10 ^2. It is preferably Ω · cm or less, and more preferably 1 × 10 ⁻² to 1 × 10 ² Ω · cm. When the resistance exceeds 1 × 10 ² Ω · cm, it becomes difficult to impart preferable conductivity to the protective layer. Also, 1 × 10 ^-2 Ω
When it is less than cm, the electrophotographic characteristics and the image characteristics are adversely affected such that the image deletion and the positive ghost are deteriorated and the environmental fluctuation of the potential is increased. The resistance can be measured as follows. First, 100 samples
By applying a pressure of kg / cm ² , a diameter of 4c
m into a disk-shaped pellet having a thickness of 0.2 cm. Then, the resistance (Ω · cm) of this pellet is changed to Hiresta AP.
(Made by Mitsubishi Yuka).

Although the detailed mechanism is not known as the reason why the tin oxide doped with tungsten element of the present invention solves the above-mentioned problems, the inventors have found that the tin oxide doped with tungsten element of the present invention It is speculated that it is related to the fact that it exhibits high conductivity and the high dispersibility of tin oxide doped with tungsten element in the resin for the protective layer or the coating liquid for the protective layer of the present invention. That is,
The residual potential is kept low by the effect of high conductivity and high dispersibility,
The charge accumulation will be reduced. As a result, the environmental fluctuation of the resistance of the protective layer becomes small, and the potential becomes stable including durability, so that the problem that the image density is low from the initial stage under low humidity and the density change at durability is large does not occur.
In addition, since the environmental change of the resistance of the protective layer is small, image defects such as image deletion and positive ghost under high humidity are eliminated, so that stable high-quality images can be obtained regardless of the environment during repeated use. Electrophotographic photosensitive member that can be obtained,
It is considered that a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be obtained. That is, as long as tin oxide doped with elemental tungsten is used as the conductive particles, the conductive particles do not need to be surface-treated.

There are two methods for further reducing the environmental fluctuation of the resistance of the protective layer containing tin oxide doped with elemental tungsten of the present invention. That is, a method of containing a third component element other than the tungsten element,
As described above, the surface treatment is applied to the tin oxide particles.

First, a method of incorporating the third component element will be described. The third component element can be contained inside or on the surface of the tin oxide particles doped with tungsten element, and when attached to the surface of the tin oxide particles, the one having further excellent stability with time of conductivity is obtained. Therefore, it is a preferable form. As the third element, silver,
Gold, magnesium, calcium, strontium, barium, aluminum, titanium, zirconium, carbon, silicon, tin, vanadium, niobium, phosphorus, bismuth, molybdenum, tungsten, manganese, iron, cobalt, nickel, ruthenium, rhodium, palladium, platinum, etc. At least one of these elements can be used, and their metals and compounds such as their oxides and hydroxides can be used. For example, elemental silicon can be contained in the state of an inorganic silicon compound such as silicic acid, silicate, silicon oxide and hydrous silicon oxide, or an organic silicon compound such as silicon alkoxide and silicon resin. In order to improve the stability of the conductivity with time or to improve the dispersibility at the time of coating, the surface of the tin oxide particles doped with tungsten element, such as aluminum, titanium, zirconium, silicon and tin. It is preferable to contain an element, and silicon is particularly preferable. In order to further improve the conductivity, tin oxide particles may be contained in the tin oxide particles doped with the elemental element of niobium or phosphorus as a dopant. The content of the third component element is preferably 0.01 to 30 mol% with respect to tin oxide, more preferably 0.01 to 20 mol%, and most preferably 0.1 to 10 mol%. Is the range. If the content of the third component element is less than the above range, it is not preferable because the effect of addition is difficult to appear, and even if it is more than the above range, further improvement is difficult to be recognized, and further, the conductivity is easily reduced. Not preferable. The conductive tin oxide containing the third component element is also in the form of fine particles, and for the same reason as the above-mentioned conductive tin oxide, the specific surface area is expressed as 5 to 2
The range is preferably 00 m ² / g, more preferably 10 to
200 m ² / g range, most preferably 30-100 m ²
/ G range.

Next, a method of treating the surface of tin oxide will be described. In this method, the surface treatment can not only improve the dispersibility and dispersion stability of the tin oxide particles, but also suppress the environmental fluctuation of the resistance of the protective layer. Examples of the surface treatment agent used for the surface treatment include various silane coupling agents, silicone oils, siloxane compounds and surfactants. In particular, a fluorine atom-containing compound is preferable from the viewpoint of dispersibility and dispersion stability of tin oxide particles.

The preferred compounds are illustrated below, but the invention is not limited to these compounds.

Examples of fluorine-containing silane coupling agents are shown in Table 1.
To list.

[0018]

[Table 1] Table 2 gives examples of fluorine-modified silicone oil.

[0019]

[Table 2] Table 3 shows examples of the fluorine-based surfactant.

[0020]

[Table 3]

General formula (1) which is an example of a siloxane compound
I will give you.

[0022]

[Chemical 1] In the general formula (1), A is a hydrogen atom or a methyl group,
Moreover, the ratio of hydrogen atoms in all A is 0.1 to 50.
% Range, n is 0 or a positive integer.

No secondary particles of dispersed particles are formed by dispersing the coating liquid after adding the siloxane compound or the surface-treated conductive fine particles in a binder resin dissolved in a solvent. As a result, a coating liquid which was stable and had good dispersibility was obtained, and a protective layer formed from this coating liquid was highly transparent and a film having particularly excellent environmental resistance was obtained.

The molecular weight of the siloxane compound represented by the general formula (1) is not particularly limited, but when the surface treatment is performed, it is better that the viscosity is not too high because of its easiness, and the weight average molecular weight is A few hundred to tens of thousands is suitable.

The surface treatment method for tin oxide particles of the present invention is as follows:
It is as follows. First, the tin oxide particles of the present invention and the surface treating agent are mixed and dispersed in a suitable solvent to adhere the surface treating agent to the surface of the tin oxide particles. As a dispersing means, a usual dispersing means such as a ball mill or a sand mill is used. Next, the solvent may be removed from this dispersion solution and the surface treatment agent may be fixed to the surface of the tin oxide particles. If necessary, a heat treatment may be further performed thereafter. Further, a catalyst for accelerating the reaction may be added to the treatment liquid. Further, if necessary, the surface-treated tin oxide particles may be further pulverized. The proportion of the surface treatment agent depends on the particle size of tin oxide, but is preferably 1 to 65% by mass, and particularly preferably 5 to 50% by mass based on the total mass of tin oxide.

In the present invention, fluorine atom-containing resin particles can be contained in the protective layer for the purpose of improving the releasability, water repellency and surface lubricity of the protective layer. The fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin and copolymers thereof. Among these, one kind or two or more kinds are appropriately selected and used. Particularly, tetrafluoroethylene resin and vinylidene fluoride resin are preferable. The molecular weight of the resin particles and the particle size of the particles can be appropriately selected and are not particularly limited.

The proportion of the fluorine atom-containing resin particles in the protective layer is preferably 70% by mass or less, more preferably 10 to 60% by mass, based on the total mass of the protective layer. When the ratio of the fluorine atom-containing resin particles exceeds 70% by mass, the mechanical strength of the protective layer may be easily lowered.

The resistance of the protective layer of the present invention is 1 × 10 ¹⁰ -1.
It is preferably × 10 ¹⁵ Ω · cm, particularly 1 × 1.
It is preferably 0 ¹¹ to 1 × 10 ¹⁴ Ω · cm. If the resistance is less than 1 × 10 ¹⁰ Ω · cm, it becomes difficult to retain electric charges, and image deletion and positive ghost are likely to occur. On the other hand, when the resistance exceeds 1 × 10 ¹⁵ Ω · cm, it becomes difficult for the electric charges to move, and the concentration becomes low and the negative ghost easily occurs. The resistance can be measured as follows. First, the distance between electrodes (D) 180 μm, the length (L) 5.9c
A protective layer of the present invention having a thickness (T) of 4 μm is provided on a comb-shaped platinum electrode having a thickness of m. Next, the current value (I) when a DC voltage (V) of 100 V is applied between the comb-shaped electrodes is measured by a pA (picoampere) meter, and the resistance ρv is obtained by the following formula.

[0029]

[Formula 1]

In the present invention, additives such as coupling agents and antioxidants may be added to the protective layer for the purpose of improving dispersibility, binding property, weather resistance and the like.

The thickness of the protective layer of the present invention is 0.2 to 10 μm.
Is preferable, and particularly preferably 0.5 to 6 μm.

The protective layer of the present invention contains tin oxide doped with elemental tungsten and a binder resin. The content of tin oxide of the present invention is 40 to 85 mass% with respect to the total mass of the protective layer.
Is preferable, and particularly preferably 50 to 75% by mass. If the content is less than 40% by mass, it becomes difficult to obtain sufficient conductivity, and if it exceeds 85% by mass, it becomes difficult to obtain sufficient mechanical strength.

The binder resin used in the protective layer is a polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, polyethylene resin, polypropylene resin, polyurethane resin, acrylic resin, epoxy resin, silicone resin, cellulose resin, polychlorinated resin. Examples thereof include vinyl resins, phosphazene resins, melamine resins and vinyl chloride-vinyl acetate copolymers. These binder resins may be used alone or in combination of two or more kinds.

Among the above binder resins, a curable resin is preferable from the viewpoints of hardness of the protective layer, abrasion resistance, dispersibility of particles and stability of dispersion liquid. In this case, a coating solution in which the tin oxide particles of the present invention are dispersed is applied onto the photosensitive layer in a solution containing a monomer or oligomer which is cured by heat or light, and after drying, the coating film is irradiated by heat or light. Is cured to form a protective layer. As such a curable resin, a phenol resin, an acrylic resin, an epoxy resin, a polyurethane resin and a siloxane resin are particularly preferable. Above all, it is preferable to use a phenol resin because the environmental change of the resistance of the surface protective layer is small.
The effect of reducing environmental fluctuations in the resistance of phenolic resin is
Without canceling the effect of reducing the resistance environment variation of the protective layer by the tungsten element-doped tin oxide of the present invention,
On the contrary, a synergistic effect is obtained, which is preferable. In particular, it is preferable to use a thermosetting resol-type phenol resin because it has a high surface hardness, excellent abrasion resistance, dispersibility of fine particles, and stability after dispersion.

The curable phenol resin is a resin generally obtained by reacting phenols with formaldehyde. There are two types of phenolic resin. Resol type obtained by adding formaldehyde to phenols in excess and reacting with an alkali catalyst, and novolac obtained by adding phenols to formaldehyde in excess and reacting with acid catalyst. Divided into types.

The resol type is also soluble in solvents such as alcohols and ketones, and when heated, it is three-dimensionally crosslinked and polymerized to form a cured product. On the other hand, the novolac type generally does not cure when heated as it is, but a cured product is produced by adding a formaldehyde source such as paraformaldehyde or hexamethylenetetramine and heating.

Generally, industrially, resole is used as a varnish for paints, adhesives, cast products and laminated products, and novolac is mainly used as a molding material and a binder.

The phenolic resin used as the binder resin in the present invention can be either of the above-mentioned resol type and novolak type, but it can be cured without adding a curing agent, the operability as a paint, etc. It is preferable to use the resol type.

In the present invention, these phenolic resins may be used alone or in combination of two or more, and
It is also possible to use a mixture of the resol type and the novolak type. Any known phenol resin may be used as the phenol resin used in the present invention.

The surface protective layer of the present invention is preferably formed by coating the photosensitive layer with a coating solution obtained by dissolving or diluting a curable phenol resin in a solvent or the like, and thereby polymerizing after coating. A reaction occurs and a hardened layer is formed. As a form of polymerization, the polymerization proceeds by addition and condensation reactions by heat, and after the surface protective layer is applied, heating causes a polymerization reaction to form a polymer cured layer.

In the present invention, "the resin is cured" means that the surface protective layer is not substantially dissolved even when the resin or the protective layer is wet with a solvent when it exists in a solution state. Say. For example, when the resin is a surface protective layer using a phenol resin, it means that the surface protective layer is almost insoluble even when wetted with an alcohol solvent such as methanol or ethanol.

Next, the support of the electrophotographic photosensitive member of the present invention will be described. As the support, any material may be used as long as it has conductivity, and for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel and indium are drum-shaped or Formed into a sheet, laminated with a metal foil such as aluminum or copper on a plastic film, deposited with aluminum, indium oxide, tin oxide, etc. on a plastic film, coated with a conductive substance alone or with a binder resin Examples of the metal include a metal, a plastic film, and a paper provided with a conductive layer.

Examples of the shape of the support include a drum shape, a sheet shape, and a belt shape, but it is desirable that the shape is most suitable for the electrophotographic apparatus to which it is applied.

Next, the photosensitive layer of the electrophotographic photosensitive member of the present invention will be described. The structure of the photosensitive layer is roughly classified into a single layer type containing both a charge generating substance and a charge transporting substance in the same layer and a laminated type having a charge generating layer and a charge transporting layer.

When the photosensitive layer is of a laminated type, the charge generating substance may be an inorganic charge generating substance such as selenium, selenium-tellurium or amorphous silicon; a pyrylium dye, a thiapyrylium dye, an azurenium dye, a thiacyanine dye and a quinocyanine. Cationic dyes such as system dyes; Squarium salt pigments; Phthalocyanine pigments; Polycyclic quinone pigments such as anthanthrone pigments, dibenzpyrenequinone pigments and pyrantrone pigments; Indigo pigments; Quinacridone pigments; and Azo pigments Examples include pigments and the like. The charge generation layer can be formed as a vapor deposition layer of these charge generation substances by a vacuum vapor deposition apparatus, or can be formed as a coating layer by applying a coating liquid dispersed or dissolved in a binder resin and drying. .

The binder resin can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, cellulose resin, urethane resin, epoxy resin, polyvinyl alcohol, etc. Resins of

The binder resin contained in the charge generation layer is preferably 80% by mass or less, and particularly preferably 50% by mass or less based on the total mass of the charge generation layer.

The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.01 to 1 μm.

The charge transport layer comprises a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene and phenanthrene in the main chain or side chain; a nitrogen-containing ring compound such as indole, carbazole, oxadiazole and pyrazoline; hydrazone compound And a charge transport substance such as a styryl compound are dissolved in a binder resin to form a coating liquid, and the coating liquid is dried.

As the binder resin, polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate resin, polyurethane, Alternatively, copolymers thereof such as styrene-butadiene copolymer, styrene-acrylonitrile copolymer and styrene-maleic acid copolymer may be mentioned. In addition to such an insulating polymer, an organic photoconductive polymer such as polyvinylcarbazole, polyvinylanthracene or polyvinylpyrene can also be used.

The ratio of the binder resin to the charge transport material is preferably 10 to 500 parts by mass of the charge transport material per 100 parts by mass of the binder resin.

The thickness of the charge transport layer is 5 to 40 μm.
Is preferable, and particularly preferably 10 to 30 μm.

When the photosensitive layer is of a single layer type, the photosensitive layer is prepared by applying a solution prepared by dispersing and dissolving the above-mentioned charge generating substance and charge transporting substance in the above-mentioned binder resin onto a support and drying. Can be formed.

In the present invention, an undercoat layer having a barrier function and an adhesive function may be provided between the support and the photosensitive layer.

Examples of the material for the undercoat layer include polyvinyl alcohol, polyethylene oxide, nitrocellulose, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, alcohol-soluble amide, polyamide, polyurethane, casein, glue and gelatin. The undercoat layer can be formed by applying a solution prepared by dissolving these materials in a suitable solvent onto a support and drying. The film thickness is preferably 5 μm or less, and particularly preferably 0.2 μm to 3 μm.

When the exposure is a laser beam, it is preferable to provide a conductive layer between the undercoat layer and the support in order to prevent interference fringes. The conductive layer can be formed by applying a solution in which a conductive powder such as carbon black and metal particles is dispersed in a binder resin on a support and drying the solution. The thickness of the conductive layer is preferably 5 to 40 μm, and particularly preferably 5 to 30 μm.

The above-mentioned various layers are formed by a coating method such as a dip coating method, a spray coating method, a beam coating method, a spinner coating method, a roller coating method, a Meyer bar coating method and a blade coating method using an appropriate organic solvent. can do.

Next, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member of the present invention will be described.

As a charging system of a process cartridge or an electrophotographic apparatus having an electrophotographic photosensitive member having the surface protective layer, a discharge charging system is mainly used. The discharge charging method includes a non-contact charging method such as corona charging and a contact charging method using a conductive roller (charging roller) as a contact charging member for discharging. The latter is a mechanism in which the surface of the member to be charged is charged with a discharge product due to a discharge phenomenon that occurs in the gap between the contact charging member and the member to be charged. A roller charging method (roller charging device) which is a contact charging method is preferable in terms of discharge stability and is widely used. in recent years,
As a charging method excellent in terms of environmental safety, member deterioration and low power consumption, a direct injection charging system which does not cause adverse effects due to discharge products since it does not generate ions has been devised. The direct injection charging is a charging mechanism that charges (charges) the surface of an object to be charged by directly giving and receiving an electric charge by contact between the contact charging member and the object to be charged at the molecular level. It is also called direct charging or injection charging. At present, as an example of the direct injection charging method, there is particle charging using a magnetic brush.

Considering the improvement of the contact density, the charging method using electrically conductive particles (particle charging) is more advantageous. Examples of conductive particles used at this time, that is, charged particles include conductive magnetic particles, and an example in which a magnetic brush charging member is formed by a magnet has been proposed. For example,
As the conductive magnetic particles that are the charged particles that form the magnetic brush layer, magnetic metal particles such as ferrite and magnetite, or particles obtained by binding these magnetic particles with a resin are used. A resistance value of 1 × 10 ⁶ to 1 × 10 ⁹ Ω · cm is used, and a particle size of 10 to 50 μm is used.

However, in the conventional magnetic brush charging,
Has a limit in improving the contact density. Therefore, by magnetic force
Eliminate particle retention and actively use the adhesive force between substances
The particle charging was reviewed from the viewpoint of
And optimization of the loading amount was achieved. As a result,
It is possible to achieve both improvement and elimination of harmful effects of particle dropout,
A particle charging type charging device has been developed. Specifically
Has a specific surface area of 5 × 10 ^Five~ 100 × 10^Fivecm²/ C
m³, Volume standard median diameter (D₅₀) Is 0.4 to 4.0
conductive particles having conductive particles of μm as the main component and conductivity
And a surface having elasticity and carrying the charged particles
A charging member composed of a particle carrier is used as an electrophotographic photoreceptor.
The charged particles carried on the electrophotographic photosensitive member
A charging device that contacts and charges the electrophotographic photosensitive member.
The resistance of the charged particles carried on the charged particle carrier is 1 × 1.
0^-1~ 1 x 10⁹Ω · cm, and the supported amount of the particles is
The value obtained by dividing the surface roughness Ra μm of the charged particle carrier is 0.0
05-1mg / cm²/ Μm is preferable. You
That is, by reducing the particle size of the charged particles,
Electrodes can be held at high density on the charged particle carrier of the charging member.
It is possible to improve the charging performance. Also, electrification
Even if particles fall off the charged object, the effect should be suppressed.
You can In addition, the amount of charged particles carried is determined by the surface roughness of the carrier.
To a certain range,
The balance between the protection and the reduction of the dropout amount is achieved at the same time.

A particle charging method using charged particles of such a small particle size, that is, charged particles mainly composed of conductive inorganic particles of the small particle size having the above-mentioned physical properties are used, and the supported amount of the charged particles on the surface of the carrier is On the other hand, in the particle charging method of adjusting within a certain range, the contact density of the charged particles with respect to the electrophotographic photosensitive member is high, and thus the method itself exhibits sufficiently excellent charging property. Furthermore, by using the tin oxide doped with the tungsten element of the present invention as the conductive particles in the protective layer, the charging property can be further improved. This is because tin oxide doped with tungsten element significantly improves the dispersion state of the conductive particles, can provide stable conductivity that is not affected by severe environmental differences to the protective layer, and further stabilizes the charging property. it is conceivable that. That is, the synergistic effect of the tin oxide of the present invention and the particle charging method using the charged particles of the small particle size can further improve the charging property and stably obtain a high-quality image regardless of the environment during repeated use. It becomes possible to provide a process cartridge and an electrophotographic apparatus that can be used.

Therefore, the electrophotographic photosensitive member of the present invention can be used in a process cartridge and an electrophotographic apparatus equipped with any of the above-mentioned charging devices, but in combination with the charging system using charged particles of small particle size. As a result, the object of the present invention can be reliably achieved.

Next, the structure and operation of an electrophotographic apparatus having the electrophotographic photosensitive member of the present invention will be described.

The first embodiment in FIG. 1 shows a schematic structure of an electrophotographic apparatus having a charging device of a non-contact charging system and having a process cartridge having the electrophotographic photosensitive member of the present invention. Reference numeral 101 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 102 in the arrow direction at a predetermined peripheral speed. In the course of rotation, the photosensitive member 101 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by a corona charger, which is the primary charging unit 103, and then an image exposing unit (such as slit exposure or laser beam scanning exposure) ( Image exposure light 104 from (not shown) is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoconductor 101. The formed electrostatic latent image is then toner-developed by the developing unit 105, and the developed toner-developed image is generated when the photoconductor 101 rotates between the photoconductor 101 and the transfer unit 106 from a sheet feeding unit (not shown). The transfer material 106 is sequentially transferred to the transfer material 107 that is synchronously taken out and fed.
The transfer material 107 that has received the image transfer is separated from the surface of the photoconductor and is introduced into the image fixing means 108 to undergo the image fixing, and is printed out to the outside of the apparatus as a copy. The surface of the photoconductor 101 after the image transfer is cleaned by the cleaning unit 109 to remove the transfer residual toner, and further, the pre-exposure light 11 from the pre-exposure unit (not shown).
After being neutralized by 0, it is repeatedly used for image formation. The primary charging means 103 may be a contact charging member using a charging roller or the like, and in that case, pre-exposure is not always necessary.

In the present invention, among the above-mentioned electrophotographic photosensitive member 101, primary charging means 103, developing means 105, cleaning means 109 and the like, a plurality of components are integrally combined to form a process cartridge, The process cartridge may be detachably attached to the main body of the electrophotographic apparatus such as a copying machine or a laser beam printer. For example, the primary charging unit 103 and the developing unit 10
5 and at least one of the cleaning means 109 are integrally supported together with the photoconductor 101 to form a cartridge,
A guide means such as a rail 112 of the apparatus body can be used to form the process cartridge 111 which can be attached to and detached from the apparatus body.

Embodiment 2 of FIG. 2 shows a schematic structure of an electrophotographic apparatus having a charging device having charged particles and having a process cartridge having the electrophotographic photosensitive member of the present invention.

An image bearing member 1 is a photosensitive member having a diameter of 30 mm. The photoconductor 1 is rotationally driven in the clockwise direction indicated by the arrow at a constant peripheral speed. The charging roller 2 is composed of charged particles m (conductive particles as charged particles), a medium resistance layer 2b as a charged particle carrier and a cored bar 2a. The charging roller 2 comes into contact with the photoconductor 1 with a predetermined amount of intrusion to form a contact portion n. The charging roller 2 is rotationally driven in the charging contact portion n in a direction (counter) opposite to the rotation direction of the photoconductor 1, and comes into contact with the surface of the photoconductor 1 with a speed difference. Further, at the time of image recording by the printer, a predetermined charging bias is applied to the charging roller 2 from the charging bias applying power source S1, whereby the peripheral surface of the photoconductor 1 is directly contacted with a predetermined polarity and potential by the direct injection charging method. It is charged.

The charged particles are added to the developer, accumulated, and supplied to the charging roller via the photoconductor together with the development of the toner. Reference numeral 60 is a developing device. The electrostatic latent image on the surface of the photoconductor 1 is developed as a toner image at the developing portion a by the developing device 60. In the developing device 60, a mixture t + m in which conductive particles m are added to the developer t is provided. The charged particles may be supplied to the charging roller 2 directly from a housing-container-shaped charged particle feeder. 60a
Is a developing sleeve, 60b is a magnet roller, 60c
Is a regulating blade, 60d is a stirring member, and S3 and S5 are applied power sources.

The printer of FIG. 2 is a toner recycling process, and the transfer residual toner remaining on the surface of the photoconductor 1 after the image transfer is not removed by a cleaner (cleaning device) for exclusive use, but the photoconductor 1 is rotated. As the toner is temporarily collected by the counter-rotating charging roller and goes around the outer circumference of the roller, the inverted toner charges are normalized, and the toner charges are sequentially discharged to the developing member a and reach the developing portion a. -Reused.

Reference numeral 4 is a laser beam scanner (exposure device) including a laser diode, a polygon mirror and the like. The laser beam scanner 4 outputs laser light whose intensity is modulated corresponding to a time-series digital image signal of target image information, and scans and exposes L the uniformly charged surface of the rotating photoconductor 1 with the laser light. By this scanning exposure L, an electrostatic latent image corresponding to target image information is formed on the surface of the rotating photoconductor 1.

Reference numeral 7 is a fixing device such as a heat fixing system. The transfer material P fed to the transfer nip portion b and transferred with the toner image on the side of the photoconductor 1 is separated from the surface of the rotary photoconductor 1 and introduced into the fixing device 7, where the toner image is fixed. And is discharged outside the apparatus as an image formed product (print copy).

Next, the main constituent members of the charger used in the present invention will be described.

<Charging Roller> The charging roller 2 is manufactured by forming the medium resistance layer 2b of rubber or foam on the cored bar 2a. The medium resistance layer 2b includes a resin (for example, urethane), conductive particles (for example, carbon black),
It is formulated with a sulfiding agent and a foaming agent, and is formed in a roller shape on the cored bar 2a. As for the hardness of the charging roller, if the hardness is too low, the shape is not stable and the contactability deteriorates.If it is too high, the charging nip cannot be secured.
Since the microscopic contact property to the surface of the photoreceptor is deteriorated, the Asker C hardness is preferably in the range of 25 to 50 degrees. The material of the charging roller is not limited to the elastic foam, but the material of the elastic body may be EPDM, urethane, NB.
Examples thereof include R, silicone rubber, IR, etc., a rubber agent in which a conductive substance such as carbon black or a metal oxide is dispersed for resistance adjustment, and those obtained by foaming these. The charging member is not limited to the charging roller, and an elastic body such as a fur brush in which each pile has elasticity can be used.

<Charged Particles> As the material of the charged particles, a mixture with other conductive inorganic particles such as metal oxides and organic substances,
Alternatively, various conductive particles such as surface-treated particles can be used. Further, since the charged particles in the present invention do not need to be magnetically restrained, they need not have magnetism.

The charged particles have a specific surface area of 5 × 10 ⁵ to 10 ^5.
It is 0 × 10 ⁵ (cm ² / cm ³ ). Within this range, good chargeability can be maintained even if the charging member is contaminated. Preferably 10 × 10 ⁵ to 80 × 10 ⁵ (cm ² / c
m ³ ), more preferably 12 × 10 ⁵ to 40
By setting it to be 10 ⁵ (cm ² / cm ³ ), the charging property and the image characteristics are further improved. The specific surface area of the charged particles was determined as follows. First, according to the BET method, a specific surface area measuring device “Gemini 2375 Ver. 5.0”
(Manufactured by Shimadzu Corp.) is used to adsorb nitrogen gas on the surface of the material, and the BET specific surface area (cm
² / g) is calculated. Next, dry type automatic densitometer "Accu
"pyc 1330" (manufactured by Shimadzu Corporation) is used to determine the true density (g / cm ³ ). At this time, a sample container of 10 cm ³ was used, and a helium gas purge was performed as a sample pretreatment at a maximum pressure of 19.5 psig (1.34 × 10 ⁵ Pa).
Do 0 times. After that, the fluctuation of the pressure in the sample chamber is 0.0 as the pressure equilibrium determination value of whether the pressure in the container has reached equilibrium.
050 / min is set as a standard, and if it is less than this value, it is regarded as an equilibrium state and the measurement is started to measure the true density automatically. The measurement is performed 5 times, and the average value thereof is calculated to obtain the true density.

Here, the specific surface area of the powder is obtained as follows.

Specific surface area (cm ² / cm ³ ) = BET specific surface area (cm ² / g) × true density (g / cm ³ ).

Further, the charged particles are 50% average on a volume basis.
Median diameter (D)₅₀) Is 0.4 to 4.0 μm
Therefore, the conductive inorganic fine particles are less than the weight average particle diameter of the toner.
It D ₅₀Is less than 0.4 μm, the charged particles become toner.
When supplied with, strong interaction with toner particles
And is difficult to separate from the toner, which is not preferable. one
One, D₅₀Becomes larger, the interaction with the toner becomes weaker.
In this case, too, the supply of charged particles is hindered. Charged particles
Child D₅₀Is greater than the weight average particle size of the toner,
Rather, it hinders the movement of toner in the world.
Yellow spots are worsened and resolution is reduced. More preferred
Shii D₅₀Is 0.5 to 3.5 μm. The measurement is below
Do so.

Laser diffraction type particle size distribution measuring device "LS-2
30 type "(manufactured by Beckman Coulter, Inc.) is attached with a liquid module, and a particle size of 0.04 to 2000 µm is set as a measurement range, and D ₅₀ of the particles is calculated from the obtained volume-based particle size distribution. The measurement is about 10 m of particles in 10 ml of methanol.
After adding 2g and dispersing with an ultrasonic disperser for 2 minutes, measuring time 9
The measurement is performed under the condition that the number of measurements is once for 0 seconds.

The preferable volume resistance of the charged particles is 1 × 10 5.
⁻¹ to 1 × 10 ⁹ Ω · cm. If it exceeds 1 × 10 ⁹ Ω · cm, the charging property will not be improved. On the other hand, 1 × 10 ^-1 Ω
If it is less than cm, the charging property of the toner under high humidity is obstructed, and the developing property is deteriorated, and the charging member is contaminated in the simultaneous developing cleaning system,
The effect of improving the charging property due to the large specific surface area cannot be obtained.

Here, the resistance of the particles is measured as follows.

A cylindrical metal cell was filled with a sample, electrodes were arranged above and below so as to contact the sample, and a load of 7 was applied to the upper electrode.
kgf / cm ² (6.86 × 10 ^-1 MPa) is added.
In this state, a voltage V is applied between the electrodes, and the resistance (volume resistivity RV) of the present invention is measured from the current I (A) flowing at that time. At this time, the electrode area is Scm ² , and the sample thickness is M (c
m) RV (Ω · cm) = 100V × Scm ² / I (A) / M
(Cm).

In the present invention, the contact area between the electrode and the sample is 2.2.
It was 6 cm ² , and the voltage V was 100V.

Generally, the charging performance is improved by reducing the particle size of the charged particles in the particle charging, but the falling of the charged particles onto the photosensitive drum 1 becomes remarkable. Since the force that can hold charged particles on the charging roller is weak adhesion,
Even if a large number of particles are supplied, it is difficult to restrain the particles, and the particles fall onto the photosensitive drum 1 to suppress the influence of a defective image on the subsequent development process and transfer paper. Therefore, ideally it is desirable to apply more evenly to the surface layer of the charging roller, but in reality, by adjusting the amount of support,
It is possible to secure the chargeability and reduce the particles to be attached at a level that does not have a harmful effect.

The amount of particles carried is determined by the average roughness R of the roller surface.
It is necessary to keep more appropriate in a. That is, the value obtained by dividing the carried amount by the average roughness Ra is preferably 1 or less, more preferably 0.3 or less. Since it is necessary to ensure charging performance, the minimum supported amount is 0.005 mg /
^{cm 2 /μm(0.25mg/cm 2, Ra = 50μm} )
Is. More preferably 0.02 mg / cm ² / μm
(1 mg / cm ² , Ra = 50 μm). That is,
The carried amount / Ra is 0.005 to 1, and more preferably,
It is preferably 0.02 to 0.3 mg / cm ² / μm.

[0087]

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

Example 1 φ30 mm × 260.5 mm
Was used as a support, and a 5% by mass methanol solution of a polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) was dip-coated on the aluminum cylinder to provide an undercoat layer having a thickness of 0.5 μm. .

Next, the Bragg angle (2θ ± 0.2 °) of the CuKα characteristic X-ray diffraction of 7.4 ° and 28.2 °.
3.5 parts of hydroxygallium phthalocyanine crystals having a strong peak and polyvinyl butyral resin (trade name:
1 part of S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd. was added to 120 parts of cyclohexanone and dispersed for 3 hours with a sand mill using 1 mmφ glass beads, and 120 parts of ethyl acetate was added to dilute it to generate a charge. A layer coating liquid was prepared. This charge generation layer coating solution is dip coated on the undercoat layer and dried at 100 ° C. for 10 minutes to give a film thickness of 0.
A 15 μm charge generation layer was formed.

FIG. 3 shows a powder X-ray diffraction pattern of the above hydroxygallium phthalocyanine crystal. The powder X-ray diffraction was measured using CuKα rays under the following conditions.

Measuring instrument used: Mac Science Co., Ltd., fully automatic X-ray diffractometer MXP18 X-ray tube: Cu tube voltage: 50 KV tube current: 300 mA scanning method: 2θ / θ scanning scanning speed: 2 deg. / Min Sampling interval: 0.020 deg. Start angle (2θ): 5 deg. Stop angle (2θ): 40 deg. Divergence slit: 0.5 deg. Scattering slit: 0.5 deg. Receiving slit: 0.3 deg. Uses curved monochromator

Next, the charge transport material 1 represented by the following formula
Copy 0

[0093]

[Chemical 2] And bisphenol Z type polycarbonate (trade name: Z
10 parts of −200, manufactured by Mitsubishi Gas Chemical Co., Inc. was dissolved in 100 parts of monochlorobenzene. This coating solution was dip-coated on the charge generation layer and dried in hot air at 105 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm.

Next, as a surface protective layer, 50 parts of tin oxide ultrafine particles doped with 7.1 mol% of tungsten element with respect to tin oxide and 150 parts of ethanol were dispersed in a sand mill for 80 hours. Then, 30 parts of a thermosetting resol type phenol resin [PL-4804, manufactured by Gunei Chemical Industry Co., Ltd.] was dissolved as a resin component to obtain a coating liquid.

Using this coating solution, a film was formed on the above charge transport layer by a dip coating method, and dried with hot air at a temperature of 145 ° C. for 1 hour to obtain a surface protective layer. At this time, the thickness of the obtained surface protective layer was measured by using an instantaneous multi-photometry system MCPD-2000 (manufactured by Otsuka Electronics Co., Ltd.) due to light interference because the thickness was 3.5 μm.
Met. Further, the dispersibility of the surface protective layer coating liquid is good,
The film surface was a uniform and even surface.

For the evaluation of the electrophotographic photosensitive member, an actual machine obtained by modifying a laser jet 4000 manufactured by Hewlett Packard Co. corresponding to the electrophotographic apparatus of FIG. 1 was used. The roller charging device was used as it was without modification.
Primary charging voltage and laser light intensity are 22 ℃ / 55% RH
The initial dark potential (Vd) and the bright potential (Vl) were adjusted to -650V and -160V, respectively. Then, low humidity environment (22 ° C / 5% RH) and high humidity environment (35
Under each condition of (° C./83% RH), 7,000 sheets were durable, and potential evaluation and image evaluation were performed. As the potential evaluation, Vd and Vl were measured before and after the endurance test.

Further, the protective layer having a thickness (T) of 4 μm was provided on the comb-shaped platinum electrode by the above-mentioned method, and the same low humidity environment (22 ° C./5% RH) and high humidity environment as the potential image evaluation environment ( The current value (I) when a DC voltage (V) of 100 V was applied between the comb-shaped electrodes at 35 ° C./83% RH),
The resistance ρv was calculated. Table 4 shows the evaluation results of potential and resistance.

Furthermore, as image evaluation, the presence or absence of light density, ghost, flow, etc. was confirmed. The results are shown in Table 5. The image evaluation was carried out in the following five-level evaluation, and the larger the number, the better. In the present invention, if it is 3 or more, the remarkable effect of the present invention can be obtained. 5: Good. 4: Very slight image defects are seen. 3: A slight image defect is seen. 2: Image defects are seen. 1: Image defects are more noticeable than 2.

Example 2 Except that in Example 1, the tin oxide ultrafine particles in the protective layer were replaced with tin oxide ultrafine particles in which 25 mol% of tungsten element was doped with respect to tin oxide. Similarly, prepare an electrophotographic photoreceptor,
An evaluation was made. The results are shown in Tables 4 and 5.

<Example 3> Example 1 was repeated except that the tin oxide ultrafine particles in the protective layer were replaced with tin oxide ultrafine particles doped with tungsten element in an amount of 0.9 mol% with respect to tin oxide. An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as in. The results are shown in Tables 4 and 5.

<Example 4> In Example 1, 4 mol% of niobium element was added to tin oxide ultrafine particles doped with tungsten element, and thermosetting resol type phenol resin [PL-4804, Gunei]. Chemical Industry Co., Ltd.] is replaced with an acrylic monomer represented by the following formula,

[0102]

[Chemical 3] A film was formed using a coating liquid containing 5 parts of 2,4-diethylthioxanthone as a photopolymerization initiator, and then dried,
An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as in Example 1 except that a surface protective layer was obtained by irradiating the surface of the high-pressure mercury lamp with a light intensity of 500 mW / cm ² for 20 seconds. The results are shown in Tables 4 and 5.

<Example 5> The same as Example 4, except that the added niobium element was replaced by 1.5 mol% of silicon element with respect to the tin oxide ultrafine particles doped with tungsten element. Then, an electrophotographic photosensitive member was produced and evaluated. The results are shown in Tables 4 and 5.

Example 6 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 4 mol% of silicon element was added to the tin oxide ultrafine particles doped with tungsten element. It was produced and evaluated. The results are shown in Tables 4 and 5.

<Example 7> In Example 1, 50 parts of the tin oxide ultrafine particles doped with tungsten element
20 parts were surface-treated with a compound represented by the following formula (treatment amount: 13%),

[0106]

[Chemical 4] The remaining 30 parts are methyl hydrogen silicone oil
[KF99, Shin-Etsu Chemical Co., Ltd.] surface treatment (treatment amount 25
%), And after being dispersed in a sand mill for 75 hours, polytetrafluoroethylene fine particles (average particle diameter 0.18 μm)
An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as in Example 1 except that 20 parts were added and dispersion was carried out for 2 hours. The results are shown in Tables 4 and 5.

<Comparative Example 1> Example 1 was repeated except that the tin oxide ultrafine particles doped with the tungsten element were replaced with the tin oxide ultrafine particles doped with 6.8 mol% of phosphorus element with respect to tin oxide. An electrophotographic photosensitive member was produced and evaluated in exactly the same manner as in Example 4. The results are shown in Tables 4 and 5.
Shown in.

Comparative Example 2 Example 4 was repeated except that the tin oxide ultrafine particles doped with the tungsten element were replaced with the tin oxide ultrafine particles doped with 7 mol% of niobium element with respect to tin oxide. An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as. The results are shown in Tables 4 and 5.

Comparative Example 3 In Example 4, the tin oxide ultrafine particles doped with the tungsten element were replaced with the tin oxide ultrafine particles doped with 6.9 mol% of titanium element with respect to tin oxide, and the tin oxide was further added. On the other hand, an electrophotographic photosensitive member was produced and evaluated in exactly the same manner as in Example 4 except that the niobium element was added by 1.5%. The results are shown in Tables 4 and 5.

<Comparative Example 4> In Comparative Example 2, 50 parts of tin oxide ultrafine particles doped with the niobium element were surface-treated in the same manner as in Example 7, and further dispersed for 78 hours by a sand mill to obtain polytetrafluoroethylene fine particles (average). Particle size 0.
18 μm) 20 parts were added and the dispersion was carried out for 2 hours.
An electrophotographic photosensitive member was produced and evaluated in exactly the same manner as Comparative Example 2. The results are shown in Tables 4 and 5.

[0111]

[Table 4]

[0112]

[Table 5]

<Example 8> An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the evaluation device and the evaluation method in Example 1 were changed as follows.
As an evaluation machine, an actual machine in which a laser jet 4000 manufactured by Hewlett Packard Co. was modified so as to correspond to the electrophotographic apparatus of FIG. 2 was used. The charging device was modified to a particle charging system. The charged particles have a specific surface area of 20 × 10 ^5.
cm ² / cm ^3, median diameter on a volume standard (D ₅₀₎ is 3.3
Conductive tin oxide particles having a resistance of 6 × 10 ¹ Ω · cm were used. In addition, the amount of charged particles carried is the amount carried / Ra.
And 0.1 mg / cm ² / μm (5 mg / cm ² , Ra =
50 μm). The applied charging bias and the amount of laser light were adjusted so that the initial dark potential (Vd) and bright potential (Vl) were −620 V and −175 V under 22 ° C./55% RH, respectively. Then, low humidity environment (22 ℃ / 5% R
H) and a high-humidity environment (35 ° C./83% RH) under the conditions of 7,000 sheets, and potential evaluation and image evaluation were performed. As the potential evaluation, Vd and Vl were measured before and after the endurance test.

Further, the protective layer having a thickness (T) of 4 μm was provided on the comb-shaped platinum electrode by the above-mentioned method, and the same low humidity environment (22 ° C./5% RH) and high humidity environment (potential image evaluation environment) were used. The current value (I) when a DC voltage (V) of 100 V was applied between the comb-shaped electrodes at 35 ° C./83% RH),
The resistance ρv was calculated. Table 6 shows the evaluation results of the potential and the resistance. The image evaluation was also carried out in the same manner as in Example 1 with a 5-step evaluation. The results of image evaluation are shown in Table 7.

<Examples 9 to 14> An electrophotographic photosensitive member was carried out in the same manner as in Example 8 except that the electrophotographic photosensitive member of each of Examples 2 to 7 was replaced with the electrophotographic photosensitive member of Example 8. Was evaluated. The results are shown in Tables 6 and 7.

[0116]

[Table 6]

[0117]

[Table 7]

[0118]

As described above, according to the present invention,
Not only there is no image defect such as low image density or change in durable density under low humidity, image deletion or ghost under high humidity, and stable high-quality images can be obtained regardless of the environment during repeated use. It has become possible to provide an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

According to the present invention, the chargeability is improved by using the electrophotographic photoreceptor having the above-mentioned protective layer and the particle charging method using the charged particles of small particle size having specific physical properties, It has also become possible to provide a process cartridge and an electrophotographic apparatus that can more stably obtain a high-quality image regardless of the environment during repeated use.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus including a discharge charging type charging device and a process cartridge having the electrophotographic photosensitive member of the present invention.

FIG. 2 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having a charging device having charged particles and having a process cartridge having the electrophotographic photosensitive member of the present invention.

FIG. 3 is a characteristic X-ray diffraction chart of CuKα of hydroxygallium phthalocyanine used in Examples of the present invention.

[Explanation of symbols]

1 Electrophotographic photoreceptor (image bearing body, charged body) 2 Charging roller (charged particle carrier, contact charging member) 2a core metal 2b flexible member 4 Exposure equipment 6 Transfer roller 7 Fixing device 60 developing device 60a Development sleeve 60b magnet roller a Development area b Transfer nip m Charged particles (conductive particles) n Charging nip t developer S1, S3, S5 Applied power supply 101 Electrophotographic photoreceptor 102 axis 103 charging means 104 exposure light 105 developing means 106 transfer means 107 transfer material 108 fixing means 109 cleaning means 110 Pre-exposure light 111 process cartridge 112 Guide

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koichi Nakata             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2H068 AA03 AA04 AA05 AA21 AA32                       BA58 BA61 BB06 BB30 BB31                       BB33 BB34 BB35 BB58 CA05                       CA37 CA60 FA07 FA16 FA18                       FA27 FC03                 2H200 FA01 GA23 GA34 GA44 GB22                       GB23 GB37 HA03 HA21 HA28                       HB12 HB17 HB22 HB45 HB46                       HB47 JA02 LC09 MA03 MA08                       MA14 MA20 MB04 MB06 MC01                       MC06 MC15 NA02

Claims (15)

[Claims] 1. An electrophotographic photoreceptor having a support, a photosensitive layer on the support and a protective layer on the photosensitive layer, wherein the protective layer contains tin oxide particles doped with elemental tungsten and a resin. Characteristic electrophotographic photoreceptor. 2. The amount of elemental tungsten in the tin oxide particles is 0.01 to 40 mol% with respect to tin oxide.
The electrophotographic photosensitive member according to 1. 3. The electrophotographic photosensitive member according to claim 2, wherein the amount of elemental tungsten relative to tin oxide is 1 to 30 mol%. 4. The electrophotographic photosensitive member according to claim 1, wherein the tin oxide particles doped with the tungsten element contain 0.01 to 30 mol% of the third component element. 5. The electrophotographic photosensitive member according to claim 1, wherein the tin oxide particles doped with elemental tungsten have a surface treating agent. 6. The binder resin is a curable resin.
5. The electrophotographic photosensitive member according to any one of 5 above. 7. The electrophotographic photosensitive member according to claim 6, wherein the curable resin is at least one resin selected from the group consisting of a phenol resin, an acrylic resin, an epoxy resin and a siloxane resin. 8. The electrophotographic photosensitive member according to claim 7, wherein the phenol resin is a resol type phenol resin. 9. The protective layer contains at least one of a fluorine atom-containing compound and a siloxane compound.
The electrophotographic photosensitive member according to any one of 1. 10. The electrophotographic photosensitive member according to claim 9, wherein the fluorine atom-containing compound is at least one compound selected from the group consisting of a fluorine-containing silane coupling agent, a fluorine-modified silicone oil and a fluorine-based surfactant. 11. The electrophotographic photosensitive member according to claim 1, wherein the protective layer contains fluorine atom-containing resin particles. 12. A process cartridge which integrally supports an electrophotographic photosensitive member and at least one unit selected from the group consisting of a charging unit, a developing unit and a cleaning unit, and which is detachable from the main body of the electrophotographic apparatus. A process cartridge, wherein the photographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 11. 13. An electrophotographic apparatus having an electrophotographic photoreceptor, a charging means, an exposing means, a developing means and a transferring means, wherein the electrophotographic photoreceptor is the electrophotographic photoreceptor according to any one of claims 1 to 11. An electrophotographic apparatus characterized in that 14. The charging means is composed of charged particles containing conductive inorganic particles as a main component and a charged particle carrier having a surface having conductivity and elasticity, and the charged particles are used as an electrophotographic photoreceptor. A charging device for charging the surface of an electrophotographic photosensitive member by contacting the charged particles, wherein the charged particles are 5 × 10 ^{5 to} 100 × 10 ⁵ cm.
Specific surface area of ² / cm ³ , volume standard median diameter (D ₅₀ ) of 0.4 to 4.0 μm, 1 × 10 ⁻¹ to 1 × 10 ⁹ Ω · cm
And a value obtained by dividing the amount of the charged particles carried by the charged particle carrier surface roughness Ra μm is 0.005 to 1 mg / cm.
13. The process cartridge according to claim 12, wherein the process cartridge has a thickness of ² / μm. 15. The charging means is composed of charged particles containing conductive inorganic particles as a main component and a charged particle carrier having a surface having conductivity and elasticity. The charged particles are used as an electrophotographic photoreceptor. A charging device for charging the surface of an electrophotographic photosensitive member by contacting the charged particles, wherein the charged particles are 5 × 10 ^{5 to} 100 × 10 ⁵ cm.
Specific surface area of ² / cm ³ , volume standard median diameter (D ₅₀ ) of 0.4 to 4.0 μm, 1 × 10 ⁻¹ to 1 × 10 ⁹ Ω · cm
And a value obtained by dividing the amount of the charged particles carried by the charged particle carrier surface roughness Ra μm is 0.005 to 1 mg / cm.
The electrophotographic apparatus according to claim 13, wherein the electrophotographic apparatus has a thickness of ² / μm.