JP2005092090A - Image forming apparatus and process cartridge for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and a process cartridge in which a photoconductor has sufficient wear resistance and can stably obtain a high quality image for a long time.
An image forming apparatus having at least an image carrier (electrophotographic photosensitive member) and an exposure device, the surface of the image carrier having a radiation cross-linking agent and a charge transport material as main components and an oxygen concentration. The relationship between the total film thickness Pd [μm] of the photoconductor and the absolute value | VD | [V] of the photoconductor surface potential is | VD | / Pd ≦ 30. An image forming apparatus characterized in that a toner having a charge amount distribution (q / d) of −0.1 [femto C / μm] or more is less than 10% by number.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus such as a printer, a digital copying machine, a facsimile, and the like, and an image forming process cartridge. More specifically, the present invention relates to an image forming apparatus and an image forming process cartridge capable of stably obtaining excellent durability and good image quality in a high-speed electrophotographic process.

In recent image forming apparatuses using an electrophotographic system, higher image quality and higher durability are required.
It is known that the contribution to the reduction in the particle size of the toner is significant in terms of improving the image quality. Conventionally, the toner has tended to be reduced in size as the manufacturing method is improved. In recent years, the toner particle diameter is controlled by a toner manufacturing method using a polymerization method, and it has become possible to further reduce the toner particle diameter. Along with this, it has become a problem to stably use small-diameter toner. In particular, controlling the toner charge amount distribution that varies depending on the external environment (temperature, humidity, number of image outputs) is important for obtaining stable image quality over time.

  For example, in Japanese Patent Laid-Open No. 8-129268 (Patent Document 1), a stable image is obtained over time by defining the ratio of uncharged toner in a two-component developer. In Japanese Patent Application Laid-Open No. 7-219275 (Patent Document 2), by defining the dispersion particle size of the charge control agent and the like, a sharp charge amount distribution is obtained for a small particle size toner, so that the toner scattering and the background contamination are obtained. This prevents the problem of image defects.

  On the other hand, with regard to high durability, it has been a hindrance to extending the life of an image forming apparatus that a photoconductor as an image bearing member is scraped and worn by a cleaning blade or the like. With respect to this, as in JP-A-57-30846 (Patent Document 3) and JP-A-4-281461 (Patent Document 4), a photoconductor as a latent image carrier is made of a metal or a metal oxide. There has been proposed a method for improving wear resistance by providing a protective layer containing a filler.

  However, organic photoconductors employing these methods have good wear resistance, but are insufficient, and are prone to filming due to toner components, etc., and dispersion of filler in the protective layer The agglomerates due to poor performance may cause the cleaning blade to deteriorate in adhesion and cause poor cleaning, or may adversely affect the electrostatic stability and durability of the photoreceptor. In fact, the desired characteristics have not yet been obtained.

  Further, it is also possible to provide a crosslinkable organopolysiloxane resin layer as a protective layer on the photoreceptor surface layer as disclosed in JP-A-61-72256 (Patent Document 5), JP-A-61-51155 (Patent Document 6), Japanese Laid-Open Patent Publication No. 1-221764 (Patent Document 7), Japanese Laid-Open Patent Publication No. 1-2003636 (Patent Document 8), Japanese Laid-Open Patent Publication No. 3-129360 (Patent Document 9), Japanese Laid-Open Patent Publication No. 3-155558 (Patent Document 10). JP-A-3-139655 (Patent Document 11), JP-A-5-40359 (Patent Document 12), and the like.

  However, the method of providing such a cross-linkable organopolysiloxane resin layer can increase the mechanical strength and abrasion resistance of the surface as compared with a conventional photoreceptor, but is still not sufficient. Another problem is that the chargeability, sensitivity, residual potential, etc. of the photoconductor may be deteriorated, and that under such conditions as high temperature and high humidity, image flow may occur and a clear image cannot be obtained. It was.

  As described above, although there are many attempts to apply the crosslinkable organopolysiloxane resin, its performance is still far from a practical level photoreceptor.

Furthermore, photoconductors using a radiation curable resin having a reactive acryloyl group or methacryloyl group as a protective layer material on the surface of the photoconductor are disclosed in JP-A-4-226469 (Patent Document 13) and JP-A-9-319130 ( Patent Document 14), Japanese Patent Application Laid-Open No. 2000-310871 (Patent Document 15), Japanese Patent Application Laid-Open No. 2001-125297 (Patent Document 16), and the like.
By using these materials, the wear resistance is improved, but the curing is not sufficient, and unreacted substances increase as the distance from the surface of the photoreceptor increases, so that filming of toner components and the like is likely to occur.

JP-A-8-129268 JP 7-219275 A Japanese Unexamined Patent Publication No. 57-30846 JP-A-4-281461 JP 61-72256 A JP-A-61-51155 JP-A-1-217364 Japanese Patent Laid-Open No. 1-200366 Japanese Patent Laid-Open No. 3-129360 Japanese Patent Laid-Open No. 3-155558 Japanese Patent Laid-Open No. 3-139655 JP-A-5-40359 JP-A-4-226469 JP-A-9-319130 JP 2000-310871 A JP 2001-125297 A

  In the above-described conventional technology, although the wear resistance of the photoconductor is improved, after 50,000 images are output, image flow, toner filming, and crushed black spots occur on the photoconductor. In the image, the image quality was greatly deteriorated. Therefore, there is a problem that a stable high image quality cannot be obtained over time depending on image output conditions.

  In particular, when the amount of toner scattered from the developing device increases, not only the inside of the apparatus is contaminated with toner, but in the image, the background is smudged with toner on the non-image area, and the toner adheres to the surface of the photoreceptor. So-called toner filming is likely to occur. As a result, a defect occurs in the output image, and the photoconductor must be replaced. Therefore, the life of the photoreceptor is shortened, which is not preferable from the viewpoint of high durability.

  An object of the present invention is to provide a highly durable and high-quality image forming apparatus and a process cartridge for the image forming apparatus, in which the photoconductor has sufficient wear resistance and can stably obtain a good image quality over a long period of time. Is to provide.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by the following configuration.

(1) The photosensitive member as a latent image carrier is an electrophotographic photosensitive member in which at least a photosensitive layer and a surface protective layer are sequentially laminated on a conductive substrate, and the surface protective layer of the photosensitive member is at least radiation. The relationship between the film thickness Pd of the photoreceptor and the absolute value | VD | of the surface potential is VD | / Pd. With the configuration of ≦ 30 [V / μm], the wear resistance of the photoreceptor is improved and the toner filming is reduced, and there is no crushed toner adhesion over time, and good image quality can be obtained over a long period of time. Can be maintained.
If the ratio of the absolute value of the photosensitive member film thickness to the surface potential exceeds 30 [V / μm], electrostatic breakdown is partially caused over time due to electrostatic stress on the photosensitive member, and the crushed toner Adhesion occurs. Therefore, the image quality deteriorates with time, and the life of the photoreceptor cannot be extended.

(2) The photosensitive member as a latent image carrier is an electrophotographic photosensitive member in which at least a photosensitive layer and a surface protective layer are sequentially laminated on a conductive substrate, and the surface protective layer of the photosensitive member is It is composed of at least a radiation cross-linking agent and a charge transport material, and is radiation cross-linked in an atmosphere having an oxygen concentration of 5% or less, and the charge amount distribution (q / d) of the toner in the developing device is −0.1 [femtoC / [mu] m] or more is less than 10% by number of toner, and it has become possible to maintain stable high image quality over a long period of time.
When the amount of toner scattered from the developing device is large, toner filming on the photoconductor is facilitated over time. Therefore, the above problem can be solved by controlling the toner charge amount distribution that causes toner scattering. The correlation between the toner scattering amount and the toner charge amount distribution will be described below.

  In the toner charge amount distribution, a toner of −0.1 [femto C / μm] or more is defined as a low charge toner, and a ratio from the total number is defined as a low charge toner rate. Further, the toner scattering level is defined as the toner scattering level, and the larger the numerical value, the worse the toner scattering. FIG. 7 shows the relationship between the low charged toner ratio and the toner scattering level. According to FIG. 7, the present inventors have found that there is a correlation between the low charged toner rate and the toner scattering level, and the toner scattering amount can be controlled by setting the low charged toner rate to a certain value or less.

  In the toner charge amount distribution in the developing device, if there are 10% by number or more of toner of −0.1 [fc / μm] or more, the toner is likely to be scattered from the developing device, and the toner filming on the photoconductor over time. Become more. Therefore, stable image quality cannot be obtained, and the life of the photoreceptor is shortened.

Moreover,
(I) the volume average particle diameter of the toner is 3 μm or more and 6 μm or less;
(ii) The volume average particle size of the carrier is 20 μm or more and 50 μm or less,
(iii) The coverage of the toner with respect to the carrier is 20% or more and 70% or less,
(iv) Since the total film thickness Pd of the photosensitive member is 25 [μm] or less, stable high image quality can be maintained over a long period of time.

  By reducing the particle size of the toner to 6 μm or less, the graininess is improved and the image quality is improved. Furthermore, by reducing the particle size of the carrier to 50 μm or less, the magnetic brush in the developing region is made more uniform, the graininess is improved, and the image quality can be further improved. When the toner particle size is less than 3 μm, toner scattering cannot be suppressed, and handling properties deteriorate. On the other hand, when the particle size of the carrier is less than 20 μm, the carrier is easily separated from the developing device due to a decrease in saturation magnetization of the carrier. As a result, scattering of the carrier and so-called carrier adhesion in which the carrier adheres to the photoconductor occur frequently, and the life of the photoconductor and the apparatus is shortened.

  By controlling the coverage of the toner with respect to the carrier to 70% or less, it is possible to maintain the weakly charged and reversely charged toner of −0.1 [femtoC / μm] or more in the toner charge amount distribution below 10% by number. The toner scattering is suppressed even with time, and there is no possibility of toner filming on the photoreceptor. Note that when the toner coverage exceeds 70%, the amount of scattered toner rapidly increases, the background stain cannot be prevented, and toner filming occurs on the photoreceptor over time. When the toner coverage is less than 20%, the toner is excessively charged, and a sufficient density cannot be obtained in development.

By making the total film thickness of the photoconductor 25 μm or less, a more faithful and sharp latent image can be formed, thereby improving dot reproducibility and obtaining an image quality excellent in graininess and sharpness. it can.
The generation mechanism of the latent image will be described below. That is, the exposure beam emitted from the exposure apparatus is incident on the charge generation layer of the photoreceptor, where photo carriers are generated. The photocarrier moves through the charge transport layer toward the surface of the photoreceptor by the internal electric field of the photoreceptor. The photocarrier cancels the charge on the surface of the photoconductor to form a latent image. In the charge transport layer, there is a tendency to diffuse mutually due to the repulsion of charges between photocarriers (self-Coulomb repulsion), thereby expanding the latent image of the dots. By reducing the film thickness of the photoreceptor, it is possible to suppress the expansion of the latent image and obtain an image with good dot reproducibility.
When the photosensitive member film thickness exceeds 25 μm, the contribution of the latent image enlargement becomes large, the dot reproducibility is deteriorated, and the image is inferior in graininess and sharpness.

  According to another aspect of the present invention, there is provided a process car characterized in that the photosensitive member and at least one means selected from a charging means, a developing means, and a cleaning means are integrally supported and detachable from the image forming apparatus main body. It consists of a bridge.

  According to the present invention, even when the characteristics of the developer fluctuate, the photoconductor has sufficient abrasion resistance and filming resistance, so that a good image quality excellent in graininess and sharpness can be obtained. It is possible to provide a highly durable and high-quality image forming apparatus and process cartridge that can be obtained stably over a long period of time.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
(Embodiment 1)
First, the entire photosensitive unit including the developing device according to the present invention will be described.
In FIG. 1, around a photosensitive drum 1 as a latent image carrier, there are a charging device 2 for charging the drum surface, an exposure 3 made of a laser beam for forming a latent image on a uniformly charged surface, A developing device 4 that forms a toner image by attaching charged toner to the latent image on the drum surface, a transfer device 5 that transfers the toner image on the formed drum to the recording paper 6, and residual toner on the drum is removed. A cleaning device 7 for removing the charge and a charge eliminating lamp 8 for removing the residual potential on the drum are arranged in this order.

  In such a configuration, the photosensitive member 1 whose surface is uniformly charged by the charging roller of the charging device 2 forms an electrostatic latent image by the exposure 3 and forms a toner image by the developing device 4. The toner image is transferred from the surface of the photosensitive drum 1 to a recording sheet conveyed from a paper supply tray (not shown) by a transfer device 5 including a transfer belt. The recording sheet S electrostatically attached to the photosensitive drum during this transfer is separated from the photosensitive drum 1 by the separation claw. The toner image on the unfixed recording paper is fixed on the recording paper by the fixing device. On the other hand, the toner remaining on the photosensitive drum without being transferred is removed and collected by the cleaning device 7. The photosensitive drum 1 from which the residual toner has been removed is initialized by the charge eliminating lamp 8 and used for the next image forming process.

The photoreceptor, which is the latent image carrier of the present invention, will be described in more detail based on the drawings.
FIG. 2 is a schematic cross-sectional view of the multilayer electrophotographic photosensitive member of the present invention. FIG. 3 is a schematic cross-sectional view of another laminated electrophotographic photosensitive member of the present invention. The electrophotographic photosensitive member of the present invention is provided with a photosensitive layer 1b on a conductive support (conductive substrate) 1a. The photosensitive layer 1b includes a charge generation layer 1c containing a charge generation material as a main component, and a charge transport layer. It is formed by stacking with a charge transport layer 1d containing a material as a main component. In the present invention, the protective layer 1e is formed as the surface layer of such an electrophotographic photosensitive member. This protective layer 1e will be described later.

The conductive support 1a has a volume resistance of 10 ¹⁰ Ωcm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, or a metal oxide such as tin oxide or indium oxide. Surface of the product by cutting, super-finishing, polishing, etc. after forming a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. It consists of a treated tube.

  The charge generation layer 1c is a layer mainly composed of a charge generation material. As the charge generation material, an inorganic or organic material is used. Typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squaric. Examples include acid dyes, phthalocyanine pigments, naphthalocyanine pigments, azulenium salt dyes, selenium, selenium-tellurium alloys, selenium-arsenic alloys, and amorphous silicon. These charge generation materials may be used alone or in combination of two or more.

  In the charge generation layer 1c, a charge generation material is appropriately dispersed together with a binder resin, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone, dichloroethane or the like by a ball mill, an attritor, a sand mill, or the like, and a dispersion is applied. Can be formed. Application is performed by dip coating, spray coating, bead coating, or the like.

  Examples of the binder resin used as appropriate include polyamide resins, polyurethane resins, polyester resins, epoxy resins, polyketone resins, polycarbonate resins, silicone resins, acrylic resins, polyvinyl butyral resins, polyvinyl formal resins, polyvinyl ketone resins, polystyrene resins, poly resins. An acrylic resin, a polyamide resin, etc. can be mentioned. The amount of the binder resin is suitably 0 to 2 parts with respect to 1 part of the charge generating material on a weight basis.

  The charge generation layer 1c can also be formed by a known vacuum thin film manufacturing method. The film thickness of the charge generation layer 1c is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.

  The charge transport layer 1d can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed.

  Among charge transport materials, low molecular charge transport materials include electron transport materials and hole transport materials.

  Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials may be used alone or as a mixture of two or more.

  Examples of hole transport materials include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane. , Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials may be used alone or as a mixture of two or more.

  When a polymer charge transport material is used as the charge transport material, it may be dissolved or dispersed in an appropriate solvent, and coated and dried to form a charge transport layer. The polymer charge transport material may be a material having a charge transporting substituent in the main chain or side chain in the low molecular charge transport material. Particularly preferred polymer charge transporting materials are polycarbonate, polyurethane, polyester, polyether, etc. Among them, the use of a polycarbonate having a triarylamine structure is advantageous.

  If necessary, an appropriate amount of a binder resin, a low molecular charge transport material, a plasticizer, a leveling agent, a lubricant and the like can be added to the polymer charge transport material.

  The binder resin used in the charge transport layer 1d together with the charge transport material is polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin. , Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, acrylic Examples thereof include thermoplastic resins such as resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenol resins, alkyd resins, and thermosetting resins.

  Examples of the plasticizer added to the charge transport layer 1d as necessary include general-purpose plasticizers such as dibutyl phthalate and dioctyl phthalate, and the amount used is 0 to 30 based on the weight of the binder resin. % Is appropriate.

  Examples of the leveling agent added to the charge transport layer 1d as necessary include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. About 0 to 1% is suitable with respect to binder resin on a weight basis.

  Examples of the solvent include tetrahydrofuran, dioxane, toluene, 2-butanone, monochlorobenzene, dichloroethane, methylene chloride and the like.

  The thickness of the charge transport layer 1d may be appropriately selected in accordance with desired photoreceptor characteristics within a range of 5 to 30 μm.

  In the present invention, the content of the charge transport material contained in the photosensitive layer is preferably 40% by weight or more of the charge transport layer. If it is less than 40% by weight, a sufficient light decay time in the high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on the photoreceptor, which is not preferable.

The charge transport layer mobility in the photoconductor of the present invention is 3 × 10 ⁻⁵ cm ² // under the condition of the charge transport layer electric field strength in the range of 2.5 × 10 ^{5 to} 5.5 × 10 ⁵ V / cm. V · s or more is preferable, and 7 × 10 ⁻⁵ cm ² / V · s or more is more preferable. This mobility can be adjusted as appropriate to achieve this under each use condition. This mobility may be obtained by a conventionally known TOF (Time Of Flight) method.

  In the laminated electrophotographic photosensitive member of the present invention, an undercoat layer can be formed between the conductive support 1a and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is applied using a solvent, the resin is a resin having high resistance to general organic solvents. Is desirable.

  Examples of such resins include polyvinyl alcohol resins, caseins, water-soluble resins such as sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane resins, melamine resins, alkyd-melamine resins, and epoxy resins. Examples thereof include curable resins that form an equal three-dimensional network structure.

  Further, fine powder of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential.

  This undercoat layer can be formed by using an appropriate solvent and coating method as in the case of the photosensitive layer.

  Furthermore, it is also useful to use a metal oxide layer formed by, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent or the like as the undercoat layer. In addition, the undercoat layer is formed by anodizing Al2O3, organic matter such as polyparaxylylene (parylene), inorganic matter such as SiO, SnO2, TiO2, ITO, CeO2 by a vacuum thin film manufacturing method. The formed one is also effective.

  The thickness of the undercoat layer is suitably from 0 to 5 μm.

  Next, the surface protective layer will be described. In the formation of the surface protective layer of the present invention, a solvent or the like may be used. Examples of the solvent in this case include the same solvents as those for forming the undercoat layer and the photosensitive layer. Instead of these solvents, reactive diluents can be used to facilitate handling.

  Examples of reactive diluents include 2-ethylhexyl acrylate, cyclohexyl acrylate, butoxyethyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, etc. Is mentioned.

  2-10 micrometers is suitable for the film thickness of a surface protective layer.

  Any radiation crosslinking agent used for forming the surface protective layer can be used as long as it is a monomer or oligomer (or prepolymer) that undergoes a polymerization reaction upon irradiation and becomes a resin upon curing.

  Examples of such a monomer or oligomer include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, and melamine acrylate. (Poly) ester acrylate reacts polybasic acid such as 1,6-hexanediol, propylene glycol (as propylene oxide) and diethylene glycol with polybasic acid such as adipic acid, phthalic anhydride, trimellitic acid and acrylic acid. It is a thing. Examples of the structure are shown in (a) to (c).

(A) Adipic acid / 1,6-hexanediol / acrylic acid

(B) Phthalic anhydride / propion oxide / acrylic acid

  (C) Trimellitic acid / diethylene glycol / acrylic acid

  (Poly) urethane acrylate is obtained by reacting an acrylate having a hydroxyl group with a compound having an isocyanate group such as tolylene diisocyanate (TDI). An example of the structure is shown in (d). HEA is an abbreviation for 2-hydroxyethyl acrylate, HDO is 1,6-hexanediol, and ADA is abbreviation for adipic acid.

  (D) HEA / TDI / HDO / ADA / HDO / TDI / HEA

  Epoxy acrylates are roughly classified into bisphenol A type, novolac type and alicyclic type from the structure, and the epoxy group of these epoxy resins is esterified with acrylic acid to make the functional group an acryloyl group. Examples of the structure are shown in (e) to (g).

  (E) Bisphenol A-epichlorohydrin type / acrylic acid

  (F) Phenol novolac-epichlorohydrin type / acrylic acid

  (G) Alicyclic / acrylic acid

  The polybutadiene acrylate is obtained by reacting a terminal OH group-containing 1,2 polybutadiene with isocyanate, 1,2-mercaptoethanol or the like, and further reacting with acrylic acid or the like. An example of the structure is shown in (h).

(H)

  Silicone acrylate is, for example, methacryl-modified by a condensation reaction (demethanol reaction) between an organofunctional trimethoxysilane and a silanol group-containing polysiloxane, and its structural example is shown in (i).

(I)

These crosslinking agents may be used alone or in combination of two or more.
Among the above crosslinking agents, polyfunctional monomers are preferable to bifunctional monomers. Furthermore, it is preferable that the polyfunctional monomer also contains at least one monomer having a short molecular chain and a high crosslinking density and having a molecular weight / functional group number of 200 or more.

  Next, the photopolymerization initiator used in the present invention can be broadly classified into a radical reaction type and an ion reaction type, and the radical reaction type is further classified into a photocleavage type and a hydrogen abstraction type. Examples of photopolymerization initiators include, but are not limited to, the following.

(1) Benzoin ether Isobutyl benzoin ether Isopropyl benzoin ether Benzoin ethyl ether Benzoin methyl ether

(2) α-Acyloxime ester 1-phenyl-1,2-propanedione-2- (o-ethoxycycarbonyl)
Oxime

(3) Benzyl ketal 2,2-dimethoxy-2-phenylacetophenone benzyl hydroxycyclohexyl phenyl ketone

(4) Acetophenone derivative Diethoxyacetophenone 2-hydroxy-2-methyl-1-phenylpropan-1-one

(5) Ketone- (ketone-amine system)
Benzophenone Chlorothioxanthone 2-Chlorothioxanthone Isopropylthioxanthone 2-Methylthioxanthone Chlorine-substituted benzophenone

  These photopolymerization initiators are used alone or in combination of two or more. The addition amount is preferably 0.005 to 1.0 part by weight, more preferably 0.01 to 0.5 part by weight, based on 1 part by weight of the crosslinking agent.

  The photopolymerization accelerator used in the present invention has an effect of improving the curing rate with respect to a hydrogen abstraction type photopolymerization initiator such as benzophenone or thioxanthone. For example, an aromatic tertiary class There are amines and aliphatic amines. Specific examples include P-dimethylaminobenzoic acid isoamyl ester, P-dimethylaminobenzoic acid ethyl ester, and the like.

  These photopolymerization accelerators are used alone or in combination of two or more. The addition amount is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 3 parts by weight, relative to 1 part by weight of the photopolymerization initiator.

  It is known that the degree of curing of the surface is lowered because oxygen in the atmosphere when curing these crosslinking agents inhibits curing. This causes scratches, filming and wear of the surface protective layer. Examples of the method for preventing the oxygen inhibition include curing the curable resin in an atmosphere having an oxygen concentration of 5% or less. Preferably it is 2% or less. By preventing oxygen inhibition, the curable resin is completely cured to the surface.

Examples of the radiation irradiation apparatus of the present invention include an ultraviolet irradiation apparatus and an electron beam irradiation apparatus.
The ultraviolet irradiation device used in the present invention includes a light source, a lamp, a power source, a cooling device, and a transport device. The light source includes a mercury lamp, a metal halide lamp, a potassium lamp, a mercury xenon lamp, and a flash lamp. A light source having an emission spectrum corresponding to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator may be used. . As for the ultraviolet irradiation conditions, the lamp output and the conveyance speed may be determined according to the irradiation energy necessary for crosslinking the crosslinking agent. Since radicals generated during ultraviolet irradiation remain for several hours, it has been confirmed that the reaction of the residual monomer proceeds by providing a residence time.

Furthermore, the crosslinking agent for the surface protective layer can be crosslinked using an electron beam. A photopolymerization initiator is not required for crosslinking by electron beams. However, since the electron beam has a large transmission power and greatly affects the photosensitive characteristics, it is difficult to obtain a stable productivity.
Also, when an electron beam is used, the oxygen concentration needs to be 2% or less due to oxygen inhibition and ozone generation.

  The charge transport material used for the surface protective layer is the same material as that used for the charge transport layer, but an acrylate or methacrylate adduct is preferred. By subjecting the acrylate or methacrylate group of the charge transport material to a crosslinking reaction with the functional group of the crosslinking agent as a binder, a coating film structure is stabilized, and a surface protective layer having better scratch resistance and abrasion resistance can be obtained.

  The content of the charge transport material contained in the surface protective layer of the present invention is preferably 30% by weight or more and 50% by weight or less of the charge transport layer. If it is less than 30% by weight, a sufficient light decay time in a high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on a photoreceptor, which is not preferable. This is because if it exceeds 50% by weight, the crosslinking reaction of the crosslinking agent is significantly adversely affected.

  In the present invention, another intermediate layer can be formed between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used as a main component. Examples of the binder resin include polyamide resin, alcohol-soluble nylon, water-soluble polyvinyl butyral resin, polyvinyl butyral resin, and polyvinyl alcohol resin.

  As a method for forming the intermediate layer, the above-described normal coating method is employed. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

  In the present invention, in order to improve environmental resistance, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, an antioxidant, a plasticizer, a lubricant, an ultraviolet absorber, and a low molecular charge transport material are used for each layer. And leveling agents can be added.

  Examples of the antioxidant that can be added to each layer include the following.

  Phenol compounds: 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4-hydroxy-3 , 5-di-tert-butylphenol), 2,2-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4-thiobis- (3-methyl-6-tert-butylphenol), 4,4-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- Methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, bis [3,3-bis (4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester , Tocopherols, etc.

  Paraphenylenediamines: N-phenyl-N-isopropyl-p-phenylenediamine, N, N-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N-di-isopropyl-p-phenylenediamine, N, N-dimethyl-N, N-di-t-butyl-p-phenylenediamine and the like.

  Hydroquinones: 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- ( 2-octadecenyl) -5-methylhydroquinone and the like.

  Organic sulfur compounds: dilauryl-3,3-thiodipropionate, distearyl-3,3-thiodipropionate, ditetradecyl-3,3-thiodipropionate, and the like.

  Organic phosphorus compounds: triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

  The following can be illustrated as a plasticizer which can be added to each layer.

  Phosphate ester plasticizer: triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, phosphoric acid Triphenyl and the like.

  Phthalate plasticizers: dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, dinonyl phthalate , Diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate, etc.

  Aromatic carboxylate plasticizers: trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.

  Aliphatic dibasic acid ester plasticizer: dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipic acid n-octyl-n-decyl, adipine Diisodecyl acid, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxy sebacate Ethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.

  Fatty acid ester derivative plasticizer: butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.

  Oxyacid ester plasticizers: methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.

  Epoxy plasticizers: epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, and the like.

  Dihydric alcohol ester plasticizer: diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate, etc.

  Chlorinated plasticizers: chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, etc.

  Polyester plasticizer: Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester, etc.

  Sulfonic acid derivative plasticizer: p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide, etc. .

  Citric acid derivative plasticizers: triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, n-octyldecyl acetyl citrate and the like.

  Others: terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.

  Moreover, the following can be illustrated as a lubricant which can be added to each layer.

  Hydrocarbon compounds: liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene, etc.

  Fatty acid compounds: lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and the like.

  Fatty acid amide compounds: stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide, etc.

  Ester compounds: lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, fatty acid polyglycol esters, and the like.

  Alcohol compounds: cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.

  Metal soap: lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.

  Natural wax: carnauba wax, candelilla wax, beeswax, whale wax, ibota wax, montan wax, etc.

  Others: silicone compounds, fluorine compounds, etc.

  The following can be illustrated as an ultraviolet absorber which can be added to each layer.

  Benzophenone ultraviolet absorbers: 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2,4-trihydroxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, etc. .

  Salsylate ultraviolet absorbers: phenyl salsylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, and the like.

  Benzotriazole ultraviolet absorbers: (2-hydroxyphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy3-tertiarybutyl 5 -Methylphenyl) 5-chlorobenzotriazole and the like.

  Cyanoacrylate ultraviolet absorbers: ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, and the like.

  Quencher (metal complex type) ultraviolet absorbers: nickel (2,2thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.

  HALS (hindered amine) ultraviolet absorbers: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl Oxy] -2,2,6,6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2, 4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine and the like.

  Furthermore, in the electrophotographic process using the electrophotographic photosensitive member of the present invention, filming can be suppressed with good wear resistance by supplying a lubricant onto the protective layer. As the lubricant used here, fatty acid metal soap such as zinc stearate, zinc laurate, zinc myristate, calcium stearate, aluminum stearate, fluororesin fine powder such as polytetrafluoroethylene, polyvinylidene fluoride and PFA, Examples thereof include fine particles of ethylene resin such as polyethylene and polypropylene. In particular, zinc stearate and calcium stearate are preferable.

  If the amount of the lubricant supplied on the photosensitive member is too large, the amount of output onto the transferred output image increases, which is not preferable because it causes a fixing failure. Further, when the friction coefficient on the surface of the photosensitive member is reduced to about 0.1 due to excessive supply of the lubricant, the image density is lowered, which is not preferable. On the other hand, when the amount of the lubricant supplied is small, filming of the toner component onto the photosensitive member occurs, which causes an image flow and halftone nonuniformity, which is not preferable. In consideration of this, for example, when a powdery lubricant is contained in the toner and supplied to the surface of the photoreceptor, a content of 0.1 to 0.2% by weight in the toner is preferable.

  An example of the configuration of the developing device (4) will be described with reference to FIG. The developing roller 41 as a developer carrying member is disposed so as to be close to the photosensitive drum 1 as a latent image carrying member, and a developing region is formed in a portion facing both of them. On the developing roller 41, a developing sleeve 43 formed of a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is rotated in the direction of the arrow, that is, in the clockwise direction by a rotation driving mechanism (not shown). It is provided as such.

  In the developing sleeve 43, a magnet roller body 44 that forms a magnetic field is provided in a fixed state so as to cause the developer to stand on the surface of the developing sleeve 43. At this time, the carrier constituting the developer is spiked in a chain shape on the developing sleeve 43 so as to follow the lines of magnetic force emitted from the magnet roller body 44, and against the carrier spiked in the chain shape. The charged toner is attached to form a magnetic brush. The formed magnetic brush is transferred in the same direction as the developing sleeve 43, that is, in the clockwise direction as the developing sleeve 43 rotates.

  A doctor blade 45 that regulates the height of the spikes of the developer chain, that is, the amount of the developer, is installed on the upstream side of the development region in the developer conveyance direction, that is, in the clockwise direction. Further, a screw 47 for pumping the developer in the developing casing 46 to the developing roller 41 side is installed in the rear area of the developing roller 41.

  A toner density sensor 48 is provided on the bottom of the developing device so as to face the screw. This toner concentration sensor is a sensor for detecting the magnetic permeability of the developer, and can detect the amount of toner in the developer by changing the magnetic permeability. The amount of toner replenished into the developing device is controlled according to the output result. A toner coverage with respect to the developer described later is calculated from the toner amount detected by the toner density sensor, and a predetermined toner amount is supplied from a toner replenishment mechanism (not shown) so that the developer has a desired coverage in the developing unit. Is replenished. The toner concentration sensor 48 is not limited to the magnetic permeability sensor of the present embodiment, and other forms such as an optical sensor may be used.

  Next, the toner used in the present invention will be described. The toner particles are a mixture of at least a binder resin, a colorant, and a release agent, melted and kneaded with a hot roll mill, cooled and solidified, and pulverized and classified into parent particles. Obtained by mixing and adhering.

  As the binder resin and the colorant in this case, all those conventionally used as the binder resin for toner are applied. Among the binder resins, those having a softening point of 90 to 150 ° C., a glass transition temperature of 50 to 70 ° C., a number average molecular weight of 2000 to 6000, and a weight average molecular weight of 8000 to 150,000 are particularly preferable. The content of the colorant in the toner particles is about 2 to 12%, which is optimal in consideration of the balance between coloring power and chargeability.

  On the other hand, as the release agent, all known ones can be used, but it is particularly preferable to use carnauba wax, montan wax, and oxidized rice wax alone or in combination. The amount of the release agent used is preferably in the range of 1 to 10% with respect to the toner resin component, and the average volume particle size of the release agent before being dispersed in the toner binder is particularly preferably 10 to 300 μm.

  Further, as the additive added externally to the toner particles, inorganic fine powders such as titanium oxide and silica are preferable, which has an effect of imparting more efficient charging.

  The toner production method is not limited to the pulverization method, and a polymerization method such as an emulsion polymerization method or a dissolution suspension method may be used.

  Next, as a feature of the carrier used in the present invention, a magnetic core particle provided with a coating layer as needed is widely used.

  As the core particles, conventionally known magnetic materials are used, and examples thereof include ferromagnetic metals such as iron, cobalt, and nickel, and alloys or compounds such as magnetite, hematite, and ferrite.

  Examples of the resin used for the coating layer include polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, Polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride / vinyl acetate copolymer; styrene / acrylic acid copolymer; silicone resin such as straight silicone resin composed of organosiloxane bond or a modified product thereof (for example, alkyd Resin, polyester, epoxy resin, polyurethane, etc.); fluorine resin, such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotopoly Boneto; amino resins such as urea-formaldehyde resins, epoxy resins and the like.

  Here, the coverage with the toner on the carrier surface in the present invention will be described in detail. In general, the coverage is often calculated using only the average particle diameter of toner and carrier. In this case, in consideration of the maximum occupied area when the toner is densely packed, the circumscribed hexagonal area of a circle having the same radius as the toner particle diameter is generally calculated as the occupied area of one toner. However, the coverage calculated using only the average particle size of the toner and the carrier is the same as long as the average particle size is the same regardless of the particle size distribution of the toner and the carrier. The filling state of the actual particle size considering the above cannot be calculated and lacks accuracy.

  Therefore, in the calculation of the coverage in the present invention, a calculation method is devised in consideration of each particle size distribution of the toner carrier. In other words, the particle size of the toner and carrier is subdivided into predetermined areas, and the total of the total toner area (total projected area of the toner) / (total surface area of the carrier) calculated for each area (total toner area). The ratio of (actual projected area) / (total actual surface area of the carrier) is calculated. According to this calculation method, the filling state closer to the observation state is quantified, and it can be considered that the coverage by the actual particle size of the toner and carrier is controlled.

  Hereinafter, the calculation method of the coverage will be described in detail. Basically, since coverage = (total projected area of toner) / (total surface area of carrier) × 100, first, the total projected area of toner and the total surface area of carrier are individually determined. First, regarding the total projected area of the toner, the particle size of the toner is measured using a particle size distribution measuring device such as a Coulter counter, and is aggregated into histogram data divided into small toner particle size distributions. Using this as each channel, the toner representative diameter Rt for each channel (the average value of the particle diameters at the upper and lower ends of the channel) and the number of toners nt contained in the channel area × the projected area of the sphere with the representative particle diameter × The number is obtained and the sum of all the channels is defined as s1.

s1 = Σ (π (Rt / 2) ² × nt).
Next, the particle mass × number of representative particle diameters of each channel is obtained, and the total is defined as w1.
w1 = Σ (4 / 3π (Rt / 2) ³ × σt × nt). Here, σt represents the density of the toner.
From the above, using s1 and w1,
(Total projected area per 1 g of toner) = s1 × (1 g / w1) is derived.

  Similarly, the total surface area of the carrier is also measured using a particle size distribution measuring device such as a Coulter counter, and is aggregated into histogram data divided into small carrier particle size distributions. Using each channel as a channel, using the carrier representative diameter Rc for each channel (the average value of the particle diameters at the upper and lower ends of the channel) and the number nc of carriers contained in the channel region, the surface area × number of spheres with a representative particle diameter And the sum of all channels is defined as s2.

s2 = Σ (4π (Rc / 2) ² × nc) × nc.
Next, the particle mass × number of representative particle diameters of each channel is obtained, and the total is defined as w2.
w2 = Σ (4 / 3π (Rc / 2) ³ × σc × nc). Here, σc represents the carrier density.
From the above, using s2 and w2,
(Total surface area per gram of carrier) = s2 × (1 g / w2) is derived.

Here, the coverage Tn is defined as the total mass Mt of the toner and the total mass Mc of the carrier.
Tn = {(total projected area per 1 g of toner) × Mt} / {(total projected area per 1 g of carrier) × Mc} × 100
Therefore, when the toner density is C (%), the following equation (1) is obtained using the above two equations (from C = 100 × Mt / (Mt + Mc), Mt / Mc = C / (100-C)).

Coverage ratio Tn = C · St / {(100−C) · Sc} × 100 (Formula 1)
* St: Total projected area per gram of toner Sc: Total projected area per gram of carrier C: Toner density

  For the toner charge amount distribution measurement in this example, an E-Spart analyzer manufactured by Hosokawa Micron Corporation was used. The measurement principle is that the toner particles are vibrated by dropping the toner particles between two electrodes having opposite polarities for acoustic vibration, and the toner particles are moved to the electrodes by the electric field action of the electrodes. The particle diameter and charge amount of each particle are calculated by simultaneously measuring the frequency and moving distance of the toner by the laser Doppler method.

  According to this apparatus, it is possible to measure the charge amount distribution of a particle group in a specific particle diameter range, and to easily measure the total charge amount of the particle group (for details of the principle of the E-spurt analyzer, see “ (Refer to pages 101 to 104 of “Japan Hardcopy '90 Proceedings”).

(Embodiment 2)
FIG. 5 shows a schematic configuration of an image forming apparatus having a process cartridge of the present invention.
The color image forming apparatus shown in FIG. 5 is a so-called tandem system, and has a configuration in which process cartridges (10) for respective colors are arranged in series.
The process cartridge for each color includes a charging device (2), a developing device (4), a cleaning device (6), and the like centering on the photoreceptor (1). Further, an exposure device (3) and an intermediate transfer device (5) are arranged for the photosensitive member of each process cartridge, and in addition, a paper transport unit, a paper transfer device (8), a fixing device (9) and the like are provided. ing.

  In the present invention, a plurality of components such as the above-described photoreceptor (1), charging device (2), developing device (4), and cleaning device (6) are integrated as a process cartridge. The process cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

Next, a color image forming operation will be described.
The photosensitive member (1), which is a latent image carrier that is rotationally driven in the direction of the arrow in each color image forming unit, is uniformly charged on the surface by the charging device (2), and is then driven and lit based on the image signal. An electrostatic latent image is formed by exposure in (3), and a toner image of each color is formed on the photoconductor in accordance with the electrostatic latent image by the developing device (4). Here, the same photoreceptor and developer as those in Embodiment 1 were used.

  The single color toner images formed on the photoconductors of the image forming units are sequentially transferred onto the intermediate transfer belt, which is the intermediate transfer device (5), so that the single color toner images are formed on the intermediate transfer belt. It is piled up. The toner remaining on the photoreceptor without being transferred to the intermediate transfer belt is collected by the cleaning device (6).

  On the other hand, the sheet as the recording material (7) is transported from a sheet feeding cassette (not shown) that stocks the sheet to the sheet transfer device (8) by the sheet conveying unit, and is superposed on the intermediate transfer belt. The image is transferred onto the paper by a paper transfer device (8). The toner image on the paper is heat-fixed by the fixing device (9) to obtain a color image.

  The results of experiments conducted to confirm the effect of the combination of the photoreceptor and exposure conditions are shown below. The present invention is not limited by these examples. All parts are parts by weight.

(Create photoconductor)
On an aluminum substrate having a diameter of 30 mm, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were applied in that order and dried to give a 3.5 μm undercoat layer, 0. An electrophotographic photoreceptor A was prepared by laminating a 15 μm charge generation layer and a 15 μm charge transport layer. At this time, each layer was applied by a dip coating method.

[Undercoat layer coating solution]
Titanium dioxide powder 400 parts Melamine resin 65 parts Alkyd resin 120 parts 2-butanone 400 parts

[Charge generation layer coating solution]
Titanylphthalocyanine 7 parts Polyvinyl butyral 5 parts 2-butanone 400 parts

[Charge transport layer coating solution]
Polycarbonate 10 parts Charge transport material of the following structural formula (Chemical Formula 10) 8 parts Tetrahydrofuran 200 parts

  A protective layer coating solution 2 having the following composition was applied to the electrophotographic photoreceptor A by a spray method, dried and cured, and a 5 μm protective layer was laminated to prepare an electrophotographic photoreceptor. The curing conditions at this time are ultraviolet ray irradiation equipment manufactured by Igraphic as an ultraviolet ray irradiation equipment, 120 W / cm metal halide type ultraviolet lamp in an oxygen concentration atmosphere of 5%, and ultraviolet irradiation at a line speed of 8 m / min. Body B was created.

[Protective layer coating solution]
Trimethylolpropane triacrylate (TMPTA manufactured by Nippon Kayaku Co., Ltd.) 10 parts Charge transport material of the above structural formula (Chemical Formula 10) 7 parts Irgacure 184 (manufactured by Nippon Ciba-Gigi Co., Ltd.) 0.5 parts Tetrahydrofuran 700 parts Cyclohexanone 200 parts

  Photoreceptor C was produced by setting the oxygen concentration of photoreceptor B at the time of ultraviolet irradiation to 20%.

  Further, as shown in Table 1, the developer was prepared at a toner coverage ratio of 4 levels (40%, 60%, 80%, 100%) with respect to the carrier. At this time, the toner charge amount distribution changes so that the peak value approaches 0 as the coverage increases as shown in FIG. Therefore, the number of toners of −0.1 [femt C / μm] or more in the q / d distribution is counted, and the ratio from the total count number (3000) is set as the low charged toner ratio. The values are also shown in Table 1. The coverage is set by adjusting the toner concentration and obtaining the coverage of the initial developer from the above formula (Formula 1).

  Image output was performed with the combination of the photoconductor and the developer, and the photoconductor durability and output image quality after 50,000 sheets were evaluated. The results are shown in Table 2. The evaluation items are toner filming on the photoreceptor and image defects in the image (density unevenness such as black spots and black streaks that are crushed toner adhesion), and the evaluation is a ranking evaluation by sensory evaluation. Ranks were ranked in the order of good, ◎, ○, Δ, ×, and Δ and × were unacceptable levels.

（実施例１〜４について）
感光体はＢを用い、感光体膜厚は２０μｍ、帯電電位を６００Ｖおよび５００Ｖとした。そのときの｜ＶＤ｜／Ｐｄは３０および２５［Ｖ／μｍ］である。現像剤は１および２を用いた。そのときの低帯電トナー率は３および７であった。
本実施例では、５万枚通紙後において、トナーフィルミングはほとんど見られず良好なレベルであり、かつ、つぶ状の黒ポチや濃度ムラなどの画像欠陥もなく良好なレベルであった。特に実施例２においては、フィルミングと画像欠陥がともに◎で、耐久性については非常に良いレベルであった。

(About Examples 1-4)
The photoconductor was B, the photoconductor film thickness was 20 μm, and the charging potential was 600V and 500V. At that time, | VD | / Pd is 30 and 25 [V / μm]. Developers 1 and 2 were used. The low charged toner ratios at that time were 3 and 7.
In this example, after passing through 50,000 sheets, the toner filming was almost not seen and was a good level, and it was a good level without image defects such as crushed black spots and density unevenness. Particularly in Example 2, filming and image defects were both excellent, and durability was at a very good level.

(About Comparative Example 1)
The photoreceptor was A, the photoreceptor film thickness was 20 μm, and the charging potential was 500V. At that time, | VD | / Pd is 25 [V / μm]. The developer used was 1. The low charged toner ratio at that time was 3.
In Comparative Example 1, after 50,000 sheets were passed, the filming was ◯ and the toner filming was not so much seen, but there were many uneven black spots and vertical stripe density unevenness, etc. The image defect was x. At this time, the wear amount from the initial stage of the photosensitive member was 8 [μm]. An image defect is caused by a decrease in the film thickness due to this wear and a scratch on the surface.

(Comparative Example 2)
The photoconductor was C, the photoconductor film thickness was 20 μm, and the charging potential was 500V. At that time, | VD | / Pd is 25 [V / μm]. The developer used was 1. The low charged toner ratio at that time was 3.
In Comparative Example 2, toner filming slightly occurred after passing 50,000 sheets, and filming was at an unacceptable level with Δ. Further, some vertical streaks caused by filming were observed, and image defects were at an unacceptable level with Δ.

(Comparative Example 3)
The photoconductor was B, the photoconductor film thickness was 20 μm, and the charging potential was 700V. At that time, | VD | / Pd is 35 [V / μm]. The developer used was 1. The low charged toner ratio at that time was 3.
In Comparative Example 3, toner filming was hardly observed after passing through 50,000 sheets, and filming was ◎. However, a lot of crushed black spots occurred in the image, and image defects were ×. It was an unacceptable level.

(Comparative Example 4)
The photoconductor was B, the photoconductor film thickness was 20 μm, and the charging potential was 500V. At that time, | VD | / Pd is 25 [V / μm]. The developer used was 3. At that time, the low charged toner ratio was 15.
In Comparative Example 4, toner filming slightly occurred after passing 50,000 sheets, and filming was at an unacceptable level with Δ. Further, some vertical streaks caused by filming were observed, and image defects were at an unacceptable level with Δ.

(Comparative Example 5)
The photoconductor was B, the photoconductor film thickness was 20 μm, and the charging potential was 500V. At that time, | VD | / Pd is 25 [V / μm]. The developer used was 4. At that time, the low charged toner ratio was 30.
In Comparative Example 5, a large amount of toner filming occurred after the passage of 50,000 sheets, and filming was at an unacceptable level as x. Further, many vertical streaks caused by filming were observed, and image defects were at an unacceptable level with x.

Next, in order to evaluate the image quality over time, the following experiment was performed.
When the toner particle size is 3 levels (4.5, 5.5, 7.0 [μm]) and the carrier particle size is 2 levels (35, 55 [μm]), the coverage is 40, 60, 80 [%]. A developer was prepared as follows. Then, a photoconductor having a film thickness of 3 levels (20, 25, 30 [μm]) was formed on the photoconductor B. Images were output from the initial stage up to 50,000 sheets by combining the developer and the photoreceptor. At that time, image evaluation was performed on the image after 50,000 sheets were output. The results are shown in Table 3.

The evaluation items were background stain, graininess, and sharpness among image quality. The background stain represents the degree of toner adhesion to the non-image area.
The graininess represents a feeling of roughness of the image, and evaluates the feeling of roughness of the halftone image from the highlight to the middle density portion.
Sharpness refers to the resolution of an image, and mainly evaluates the edge of a character image and the dust on a line.
The evaluation was ranked by sensory evaluation.
Ranks were ranked in the order of good, ◎, ○, Δ, and ×, and Δ and × were unacceptable levels.

(About Examples 5 to 10)
The developer was prepared such that the toner particle diameter was 4.5 and 5.5 [μm], the carrier particle diameter was 35 [μm], and the coverage was 40 and 60%. The photoreceptors had film thicknesses of 20 and 24 [μm].
In any of Examples 5 to 10, it was confirmed that the image quality after passing through 50,000 sheets was free from background stains, and the graininess and sharpness were at good levels. In particular, in Example 5, the graininess and sharpness were both excellent and very good.

(Comparative Example 6)
The developer had a toner particle size of 7.0 [μm], a carrier particle size of 35 [μm], and a coverage of 40 [%]. The photoreceptor had a film thickness of 20 [μm].
In Comparative Example 6, the background stain was ◎ and a good level, but the graininess was particularly bad at x, and the sharpness was Δ and was not an acceptable level.

(Comparative Example 7)
The developer had a toner particle size of 4.5 [μm], a carrier particle size of 55 [μm], and a coverage of 40 [%]. The photoreceptor had a film thickness of 20 [μm].
In Comparative Example 7, the background stain was ◎ and a good level, but the graininess was Δ and the sharpness was Δ, both of which were poor and not acceptable.

(Comparative Example 8)
The developer had a toner particle size of 4.5 [μm], a carrier particle size of 35 [μm], and a coverage of 80 [%]. The photoreceptor had a film thickness of 20 [μm].
In Comparative Example 8, the background stain was very bad at x and was not at an acceptable level. In addition, the graininess may be ○, but the sharpness is mostly dusty and Δ is not acceptable.

(Comparative Example 9)
The developer had a toner particle size of 4.5 [μm], a carrier particle size of 35 [μm], and a coverage of 40 [%]. The photoreceptor had a film thickness of 30 [μm].
In Comparative Example 9, the background stain was ◎ and a good level, but the graininess was Δ and the sharpness was Δ, both being bad and not acceptable. In particular, the reproducibility of dots was poor, and the feeling of roughness was conspicuous in the highlight area.

It is a figure of the whole photoreceptor unit containing a developing device. 3 is another schematic drawing of a multilayer electrophotographic photosensitive member. 3 is another schematic drawing of a multilayer electrophotographic photosensitive member. It is a figure which shows an example of a structure of a developing device. 1 is a schematic configuration diagram of an image forming apparatus having a process cartridge of the present invention. FIG. 6 is a diagram illustrating a relationship between a toner coating ratio with respect to a carrier and a charge amount. It is a figure showing the relationship between a low charged toner rate and a toner scattering level.

Explanation of symbols

(In Fig. 1)
DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging apparatus 3 Exposure 4 Developing apparatus 5 Transfer apparatus 6 Recording paper 7 Cleaning apparatus 8 Static elimination lamp (in FIG. 2, 3)
1a conductive support 1b photosensitive layer 1c charge generation layer 1d charge transport layer 1e protective layer (in FIG. 4)
DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing apparatus 41 Developing roller 43 Developing sleeve 44 Magnet roller body 45 Doctor blade 46 Developing casing 47 Screw 48 Toner density sensor (about FIG. 5)
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging apparatus 3 Exposure apparatus 4 Developing apparatus 5 Intermediate transfer apparatus 6 Cleaning apparatus 7 Recording material 8 Paper transfer apparatus 9 Fixing apparatus

Claims (14)

An image forming apparatus comprising at least an image carrier, an exposure device that exposes the image carrier to form an electrostatic latent image, and a developing device that develops the electrostatic latent image formed on the image carrier. In
The image carrier is an electrophotographic photosensitive member obtained by sequentially laminating at least a photosensitive layer and a surface protective layer on a conductive substrate, and the surface protective layer of the photosensitive member includes at least a radiation cross-linking agent and a charge transport material as main components. The relationship between the total film thickness Pd [μm] of the photosensitive member and the absolute value | VD | [V] of the photosensitive member surface potential is | VD | / An image forming apparatus satisfying Pd ≦ 30.   2. The image forming apparatus according to claim 1, wherein the toner charge amount distribution (q / d) in the developing device is less than 10% by number of toner of −0.1 [femto C / μm] or more. . An image forming apparatus comprising at least an image carrier, an exposure device that exposes the image carrier to form an electrostatic latent image, and a developing device that develops the electrostatic latent image formed on the image carrier. In
The image carrier is an electrophotographic photosensitive member obtained by sequentially laminating at least a photosensitive layer and a surface protective layer on a conductive substrate, and the surface protective layer of the photosensitive member includes at least a radiation cross-linking agent and a charge transport material as main components. Less than 10% by number of toners that are radiation-crosslinked in an atmosphere having an oxygen concentration of 5% or less and that have a toner charge amount distribution (q / d) in the developing device of −0.1 [femto C / μm] or more. An image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the toner has a volume average particle diameter of 3 μm to 6 μm.   5. The image forming apparatus according to claim 1, wherein the carrier has a volume average particle diameter of 20 μm or more and 50 μm or less.   The image forming apparatus according to claim 1, wherein a coverage ratio of the toner with respect to the carrier is 20% or more and 70% or less.   The image forming apparatus according to claim 1, wherein a total film thickness Pd of the photosensitive member is 25 [μm] or less.   The image carrier is formed by sequentially laminating at least a photosensitive layer and a surface protective layer on a conductive substrate, and the surface protective layer comprises at least a radiation cross-linking agent, a charge transport material and a photopolymerization initiator as main components and an oxygen concentration. The image forming apparatus according to any one of claims 1 to 7, wherein the image forming apparatus is an electrophotographic photosensitive member that is ultraviolet-crosslinked in an atmosphere of 5% or less.   9. The image formation according to claim 1, wherein the content of the charge transporting material contained in the surface protective layer of the image carrier is 30% by weight or more and 50% by weight or less. apparatus.   The image forming apparatus according to claim 1, wherein the radiation-crosslinking resin of the image carrier has at least one molecular weight / functional group number of 200 or less.   11. The image forming apparatus according to claim 1, wherein the radiation crosslinking resin contained in the surface protective layer of the image carrier has at least one molecular weight / functional group number of 200 or less. .   12. The image forming apparatus according to claim 1, wherein the charge transport material in the surface protective layer of the image carrier is an acrylate or methacrylate adduct.   The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus having a plurality of the image carriers.   The image carrier according to any one of claims 1 to 13, and at least one means selected from a charging means, a developing means, and a cleaning means are integrally supported, and are detachable from the main body of the image forming apparatus. A process cartridge for an image forming apparatus.

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