JP2008070585A - Image forming method, device, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide excellent images by using a reliable cleaning unit which prevents the cleaning blade from degrading by small and spherical toner, and does not make defective cleaning without degrading the wear-proof property of the photoreceptor and with less photoreceptor degradation such as filming. <P>SOLUTION: The image forming method makes static charging, image exposing, developing, image transferring, and cleaning to the photoreceptor. Its cleaning unit has an elastic blade which has a repeated waving or triangular waving shape at a right angle against the contact edge when cut at its tip end touching the photoreceptor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming method, an image forming apparatus, and a process cartridge for an image forming apparatus. More specifically, the present invention can suppress the occurrence of poor cleaning in a cleaning portion in an image forming process, and can be applied to a spherical toner having a small particle diameter. Image forming method, image forming apparatus, and process cartridge for image forming apparatus capable of obtaining good cleaning characteristics, suppressing blade wear and local defects during use over time, and obtaining a stable image It is about.

An electrophotographic method using the Carlson process and various modifications of this process is widely used in the electrophotographic field such as a copying machine, a facsimile machine, and a printer.
As an electrophotographic photosensitive member used in this electrophotographic method (hereinafter sometimes simply referred to as a photosensitive member), organic photosensitive materials have been widely used in recent years because of advantages such as low cost, mass productivity, and non-pollution. In addition, various measures have been taken for durability, such as addition of a protective layer.
Further, as a toner used in this electrophotographic method, in addition to stabilization of charging, there is an increasing demand for a reduction in particle size and spheroidization, in addition to stabilization of charging.
In order to improve the functions of such an electrophotographic supply, it has become necessary to improve the functions and optimization of the components related to them to achieve high durability and high image quality. In particular, the technique related to cleaning is closely related to each element of the electrophotographic process and has a great influence on the output image.

  As the durability of photoconductors, mechanical durability, mainly wear resistance, has been strongly demanded. However, in conventional organic photoconductors (OPC) and electrophotographic processes using the photoconductor, Due to the low wear resistance, it is clear that sufficient durability has not been obtained, and on the other hand, it has become clear that the thinning of the photosensitive layer is essential for high definition of the output image, The margin for wear is becoming stricter.

Here, since these wear phenomena are mainly caused by the cleaning process, the cleaning unit as a contact member to the photosensitive member and the toner related to the cleaning are greatly affected. And optimization are essential.
More importantly, the reduction in particle size and spheroidization of the toner used clearly reduces the cleaning margin, and cannot be handled by simply changing the setting conditions of a conventional cleaning device. Therefore, it is necessary to develop a new cleaning method and apparatus. The small particle size and spherical toner referred to here is a toner having a volume average particle size of 5.5 μm or less and a circularity of 0.97 or more for the purpose of improving the image quality. It has become.

  As a manufacturing method for reducing the toner particle size, the polymerization method is effective rather than the conventional pulverization method from the viewpoint of manufacturing cost, and the small particle size toner manufactured by the polymerization method has a nearly spherical shape and a particle size distribution. Since it is sharp, it has excellent reproducibility of fine lines and dot reproducibility of digital images, and can achieve high image quality.

With respect to the above-described problems related to cleaning, particularly in the case of a small toner having a small particle diameter and spherical toner, the occurrence of cleaning failure due to wear of the contact portion of the blade and local defects has become a major problem. For such a situation, a certain size groove is formed along the longitudinal direction of the contact portion of the blade member with the photosensitive drum, and stress applied to the tip portion along the longitudinal direction of the blade member is applied. What is reduced is disclosed. (For example, see Patent Document 1)

Also disclosed is a device that suppresses wear loss caused by local stress by forming a curved surface at the sliding contact portion with the photosensitive drum and setting the curvature radius of the curved surface within a certain range. ing. (For example, see Patent Document 2)
Further, in the cleaning blade that contacts the photoreceptor containing amorphous silicon carbide, the contact edge portion with the photoreceptor is roughened by the wrapping tape, so that the external additive in the toner is selectively cleaned. There is disclosed a configuration in which the blade and the surface of the photosensitive member can be slipped through, and good cleaning can be performed without reducing the life of the photosensitive drum and the cleaning blade. (For example, see Patent Document 3)

However, the cleaning methods related to the cleaning blade described above are those that maintain good cleaning performance, blade wear resistance, and photoreceptor wear and filming properties for small toners and spherical toners. The situation is that we have not been able to achieve these issues.
JP 2000-276019 A JP 2001-154553 A JP 2001-142371 A

  The object of the present invention is to eliminate such drawbacks of the prior art, and in particular, can be applied to a high durability digital high-speed electrophotographic process using a laser beam as a writing light source, which has become the mainstream in recent years. It is possible to obtain an excellent image with a stable cleaning device that prevents deterioration of the cleaning blade with respect to a small particle size, spherical toner, and does not cause poor cleaning. An object of the present invention is to provide an image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus.

In order to solve the above-mentioned problems, the present inventors have intensively studied with a particular focus on a cleaning unit that performs a cleaning process. As a result, the present invention has been completed.
That is, the above-mentioned problem is (1) of the present invention. In the image forming method in which at least the photosensitive member is charged, image exposed, developed, transferred, and cleaned, the cleaning unit that performs the cleaning processing has an elastic blade. A contact cut surface is formed on a portion of the elastic blade that contacts the photosensitive member, and the contact cut surface has a corrugated or triangular wave repetitive shape substantially perpendicular to the contact side. Image forming method ”, (2)“ Repetitive shape of contact cut surface with photoconductor in elastic blade has uneven height of 10 μm to 15 μm and uneven pitch of 10 μm to 20 μm Image forming method described in item (1) ”, (3)“ The elastic blade is made of urethane rubber and has a hardness of 67 to 75 degrees at 25 ° C. (JIS A The rebound resilience is 50 to 68%, and the image forming method according to (1) or (2) above, (4) “The photoconductor has a protective layer, The image forming method according to any one of (1) to (3) above, wherein the protective layer contains inorganic fine particles made of alumina or titanium oxide. The image forming method as described in item (4) above, wherein the photosensitive member protective layer contains a charge transport material, and (6) “the toner used in the development processing is a volume average particle. This is achieved by the image forming method according to any one of (1) to (5) above, wherein the diameter is 5.5 μm or less and the circularity is 0.97 or more.

  In the image forming apparatus having (7) “at least the photosensitive member, the charging unit, the image exposing unit, the developing unit, the transferring unit, and the cleaning unit, the cleaning unit that performs the cleaning process has an elastic blade. A contact cut surface is formed on a portion of the elastic blade contacting the photoreceptor, and the contact cut surface has a corrugated or triangular wave repetitive shape substantially perpendicular to the contact side. (8) “Repetitive shape of contact cut surface with the photosensitive member in the elastic blade is characterized in that the uneven height is 10 μm to 15 μm and the uneven pitch is 10 μm to 20 μm. (9) “The elastic blade is made of urethane rubber and has a hardness of 67 to 75 at 25 ° C. (JIS A), wherein the rebound resilience is 50 to 68%, and the image forming apparatus according to (7) or (8) above, (10) “The photoconductor is a protective layer” The image forming apparatus according to any one of (7) to (9) above, wherein the protective layer contains inorganic fine particles made of alumina or titanium oxide. (11) “The image forming apparatus according to (10) above, wherein the photoconductor protective layer contains a charge transport material”, (12) “Toner used in the developing unit” The image forming apparatus according to any one of (7) to (11) above, wherein the volume average particle size is 5.5 μm or less and the circularity is 0.97 or more. ) “The image forming method according to any one of (1) to (6) above, The image forming apparatus according to any one of (7) to (12) includes a cleaning unit including an elastic blade having a repeated shape of at least a contact cut surface. This is achieved by a “process cartridge for an image forming apparatus”.

The present invention is described in detail below.
The present inventors examined a cleaning method that can suppress the occurrence of defective cleaning. In particular, with respect to small particle size and spherical toner typified by polymerized toner, it was examined in detail how the cleaning can be performed stably.
When a small particle size and spherical toner is used, the cleaning toner that is blocked at the blade edge is abraded, resulting in a problem of poor cleaning. As for the particle size, of course, these toner particles have a distribution, but can be almost discussed in terms of the average particle size. When the circularity is 0.94 or less, the cleaning is possible even when the particle size is around 5 μm, whereas when the circularity is 0.97 or more, the cleaning margin decreases rapidly. However, when the particle size is about 5 μm, the conventional blade cleaning device can hardly perform cleaning, and the cleaning state varies greatly depending on the characteristics of the toner to be cleaned.

  In addition, an external additive is added to the toner in order to improve its fluidity and adjust the chargeability, but the external additive is partly removed from the toner and enters the cleaning section with the external additive alone. To do. This external additive has a very small particle size compared to the toner, and easily passes through the cleaning blade. Accordingly, the external additive is present between the blade edge and the surface of the photosensitive member in the cleaning operation, whereby both the photosensitive member and the cleaning blade are subjected to wear. In addition to abrasion, filming may occur due to the continued pressing of these external additives against the surface of the photoreceptor, and it is not easy to deal with them. In addition to the commonly used external additives, a large particle size external additive may be further added. This large particle size external additive is considered to have an effect of hindering the rotational motility of the spherical toner cleaning, and the cleaning performance margin is improved.

The use ratio of the external additive may be 0.01 to 5.0% by weight of the toner, and preferably 0.01 to 2.0% by weight. Examples of external additives include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, Examples thereof include chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

On the other hand, when the abrasion state of the blade tip in contact with the photosensitive member was examined in more detail, it was found that the wear amount with time was very large in the small particle size and spherical toner as compared with the conventional pulverized toner. The cause of this is not clear, but it is presumed that the decrease in the cleaning margin due to the small particle size and the spherical shape was affected, and the increase in the amount of toner passing through the blade is considered to be one factor. Further, it is confirmed from the detailed observation of the wear state that the wear often occurs from the cut surface of the blade, which is considered to be a result of the wear action while the blade edge is drawn in the photosensitive member operating direction.
The present invention was obtained as a result of intensive studies aimed at suppressing such wear action, and is considered to be a result of the blade edge being drawn and the deformation being mitigated. In addition, it has been found that the photoconductor cleaning and filming, and photoconductor wear and blade wear can be suppressed in a well-balanced manner, and the configuration of the present invention is effective. That is, by using the elastic body blade of the present invention, it is possible to achieve a good cleaning property by suppressing slip-through with respect to a small particle diameter and spherical toner, and to maintain good wear durability of the photoreceptor and the blade.

  Here, considering the cleaning operation near the blade edge, in the conventional straight and flat uniform cut surface shape, the blade tip is constantly drawn in the photosensitive member operation direction and undergoes deformation. The part that is several μm away from the edge part to the cut surface comes into contact with it and is subjected to wear action, and the part gradually wears out and wear progresses. It has become a phenomenon that leads to. In order to relieve such deformation, it is only necessary to make the deformation degree of the edge non-uniform, and by forming the repeated shape of the present invention on the cut surface, a plurality of relaxation points are locally formed, The effect of being drawn in from that location and eliminating the deformation is obtained. However, if the cut surface is simply roughened with abrasive paper or the like, there are many cases where a point of occurrence of defective cleaning is formed on the contrary, and the corrugated or triangular wave repeating shape of the present invention is suitable. The repetitive shape of the present invention has unevenness as a target, hardly induces local slip-out of toner, and can be simultaneously drawn to reduce deformation. In another shape, for example, in the case of a repetitive rectangular shape, a rectangular shape Not suitable because it tends to chip at the corners.

  Furthermore, the size of the repetitive shape also affects, and it is necessary that the uneven height is 10 μm to 15 μm and the uneven pitch is 10 μm to 20 μm. When the height of the unevenness is less than 10 μm, the state is the same as the flat cut, and when it is larger than 15 μm, the toner is steadily retained in the recesses and easily causes a cleaning failure. Similarly, when the uneven pitch is smaller than 10 μm, toner stays in the recesses easily, leading to poor cleaning. When the uneven pitch is larger than 20 μm, it is confirmed that the state is substantially the same as that of the flat cut. Here, the concavo-convex pitch is a repetition interval of a repetitive shape in which the concavo-convex changes symmetrically, and is an interval between adjacent convex portions or concave portions.

Further, the hardness and the rebound resilience of the elastic blade are preferably within the scope of the present invention. That is, at 25 ° C., the hardness is 67 to 75 degrees (JIS A) and the rebound resilience is 50 to 68%, so that the above-described pull-in deformation can be achieved while maintaining good cleaning properties for small particle size and spherical toner. It is preferable for the suppression. If the hardness is less than 67 degrees, the shape is more easily deformed and the effect of the shape is lost. Conversely, if the hardness is greater than 75 degrees, the adhesion to the surface of the photoreceptor is hindered and the cleaning performance is deteriorated. As for the impact resilience, if it is drawn and has a great influence on the deformation, and is less than 50%, the resilience from the deformation is low, so it is difficult to be relaxed from the deformed state. It should be noted that there is substantially no rebound resilience exceeding 68%, which is not suitable because there is a problem that the blade squeal becomes large. Here, the rebound resilience was measured according to JIS K6255 using a resilient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.).
Note that the deformation state of the edge tip can be inferred from the wear scar, and if there is wear on the cut surface, it can be determined that deformation has occurred due to drawing. The detailed wear state can be enlarged and observed with an ultra-deep shape measuring microscope VK8500 (manufactured by Keyence Corporation), and can be comparatively evaluated including wear dimensions.

Next, the photoconductor used in the present invention will be described.
The photosensitive member may be either a single layer or a stacked layer, but a function separation type stacked type will be described as an example.
FIG. 1 is a schematic cross-sectional view of a multilayer electrophotographic photosensitive member used in the present invention.
FIG. 2 is a schematic cross-sectional view of another laminated electrophotographic photosensitive member used in the present invention.
The electrophotographic photosensitive member used in the present invention is provided with a photosensitive layer (2) on a conductive support (conductive substrate) (1), and the photosensitive layer (2) is mainly composed of a charge generating material. And a charge transport layer (4) mainly composed of a charge transport material.

And a protective layer (5) is formed as a surface layer of such an electrophotographic photoreceptor. This protective layer (5) will be described later.
The conductive support (1) is one having a volume resistance of 10 ¹⁰ Ωcm or less, such as a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, tin oxide, indium oxide, etc. Metal oxide film or cylindrical plastic or paper coated by vapor deposition or sputtering, aluminum, aluminum alloy, nickel, stainless steel plate or the like, and then cutting, superfinishing, polishing, etc. It consists of a tube surface treated with
As the charge generation material in the charge generation layer (3), an inorganic or organic material is used. Typical examples include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, and quinones. And polycondensed polycyclic compounds, squaric 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 (3), the charge generation material is dispersed by a ball mill, attritor, sand mill or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, 2-butanone or dichloroethane together with a binder resin, and a dispersion is applied. Can be formed. The application is performed by a dip coating method, a spray coating method, a bead coating method, 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 (3) can also be formed by a known vacuum thin film production method.
The film thickness of the charge generation layer (3) is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer (4) can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate 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 transport materials are polycarbonate, polyurethane, polyester, polyether, etc. Among them, 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 (4) together with the charge transport material includes polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polychlorinated resin. Vinyl 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 And thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.
If necessary, examples of the plasticizer added to the charge transport layer (4) include general-purpose plasticizers such as dibutyl phthalate and dioctyl phthalate, and the amount used is based on the weight of the binder resin. About 0 to 30% is appropriate.

Examples of leveling agents added to the charge transport layer (4) include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount is suitably about 0 to 1% based on the weight of the binder resin.
Examples of the solvent include tetrahydrofuran, dioxane, toluene, 2-butanone, monochlorobenzene, dichloroethane, methylene chloride and the like.
The thickness of the charge transport layer (4) may be appropriately selected in the range of 5 to 30 μm according to desired photoreceptor characteristics.

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 a high-speed electrophotographic process cannot be obtained in pulsed light exposure in laser writing on a photoreceptor, which is not preferable.
The charge transport layer mobility in the photoreceptor is 3 × 10 ⁻⁵ cm ² / V · s under conditions of the charge transport layer electric field strength in the range of 2.5 × 10 ^{5 to} 5.5 × 10 ⁵ V / cm. It is preferable that
More preferably, it is 7 × 10 ⁻⁵ cm ² / V · s or more.
This mobility can be adjusted as appropriate to achieve this under each use condition.
This mobility may be obtained by a conventionally known (Time Of Flight) method.

In the multilayer electrophotographic photosensitive member used in the present invention, an undercoat layer can be formed between the conductive support (1) and the photosensitive layer.
This subbing layer generally comprises a resin as a main component, but these resins are resins that are highly soluble in general organic solvents in consideration of applying a photosensitive layer thereon using a solvent. It 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 Al ₂ O ₃ , organic materials such as polyparaxylylene (parylene), inorganic materials such as SiO, SnO ₂ , TiO ₂ , ITO, and CeO _2. It is also effective to form the film by a vacuum thin film manufacturing method.
The thickness of the undercoat layer is suitably 5 μm or less.

In the multilayer electrophotographic photoreceptor, it is preferable to form a protective layer (5) containing a filler on the photosensitive layer (2) as a surface layer for the purpose of protecting the photosensitive layer and improving durability.
Materials used for the protective layer (5) include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, Polyacrylate resin, polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin, polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, Examples of the resin include polysulfone resin, AS resin, AB resin, BS resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, and epoxy resin.

A filler is added to the protective layer (5) for the purpose of improving the wear resistance.
As the filler, fine powder made of an inorganic material of alumina or titanium oxide is used in the present invention. In some cases, these fillers are used together or inorganic fine particles such as silica are added.
The amount of filler added to the protective layer (5) is usually 10 to 40%, preferably 20 to 30% on a weight basis.
If the amount of the filler is less than 10%, the wear is large and the durability is inferior. If it exceeds 40%, the bright portion potential at the time of exposure increases remarkably, and the sensitivity reduction cannot be ignored.

Furthermore, a dispersion aid can be added to the protective layer (5) in order to improve the dispersibility of the filler.
As the added dispersion aid, those used in coatings and the like (for example, modified epoxy resin condensate, unsaturated polycarboxylic acid low molecular weight polymer, etc.) can be used as appropriate, and the amount is based on weight and usually contains filler. The amount is 0.5 to 4%, preferably 1 to 2%.
Moreover, it is very effective to add the above-mentioned charge transport material to the protective layer (5), and the addition amount may be the same, and the characteristics for exposure can be improved.
Further, an antioxidant can be added as necessary. The antioxidant will be described later.

As a method for forming the protective layer (5), a normal coating method such as a spray method is adopted, and the thickness of the protective layer (5) is suitably about 0.5 to 10 μm, preferably about 4 to 6 μm.
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 the method for forming the intermediate layer, the above-described normal coating method is adopted, and 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.
Antioxidants that can be added to each layer include phenol compounds such as 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 − Droxybenzyl) benzene, tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, bis [3,3-bis (4-hydroxy-3-tert-butyl) Phenyl) butyric acid] glycol ester, tocopherols and the like.

As paraphenylenediamines, N-phenyl-N-isopropyl-p-phenylenediamine, N, N-di-sec-butyl-p-phenylenediamine, N-phenyl-Nsec-butyl-p-phenylenediamine, N, N -Di-isopropyl-p-phenylenediamine, N, N-dimethyl-N, N-di-t-butyl-p-phenylenediamine and the like.
As 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.
Examples of organic sulfur compounds include dilauryl-3,3-thiodipropionate, distearyl-3,3-thiodipropionate, and ditetradecyl-3,3-thiodipropionate.

Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, and tri (2,4-dibutylphenoxy) phosphine.
Plasticizers that can be added to each layer include phosphate ester plasticizers such as triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichlorethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, Examples include tri-2-ethylhexyl phosphate and triphenyl phosphate.

As phthalate ester plasticizers, dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalic acid Dinonyl, 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. Is mentioned.
Examples of the aromatic carboxylate plasticizer include trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.
As an aliphatic dibasic ester plasticizer, dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipate-n-octyl-n-decyl, Diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-sebacate Examples thereof include ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, and di-n-octyl tetrahydrophthalate.

Examples of the fatty acid ester derivative plasticizer include butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, and tributyrin.
Examples of the oxyester plasticizer include methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, and tributyl acetyl citrate.
Epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. Is mentioned.
Examples of the dihydric alcohol ester plasticizer include diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate.

Examples of the chlorine-containing plasticizer include chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, and methoxychlorinated fatty acid methyl.
Examples of the polyester plasticizer include polypropylene adipate, polypropylene sebacate, polyester, and acetylated polyester.
As sulfonic acid derivative plasticizers, p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide Etc.
Examples of the citric acid derivative plasticizer include triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and acetyl citrate-n-octyldecyl.

Other examples include terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietic acid, and the like.
Examples of ultraviolet absorbers that can be added to each layer include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2,4-trihydroxybenzophenone, 2,2,4,4-tetrahydroxybenzophenone as benzophenone-based ultraviolet absorbers. 2,2-dihydroxy-4-methoxybenzophenone and the like.

Examples of the salicylate ultraviolet absorber include phenyl salicylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and the like.
Examples of the benzotriazole ultraviolet absorber include (2-hydroxyphenyl) benzotriazole, (2-hydroxy5-methylphenyl) benzotriazole, (2-hydroxy-5-methylphenyl) benzotriazole, (2-hydroxy-3-tarsha). Ributyl-5-methylphenyl) 5-chlorobenzotriazole and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3-diphenyl acrylate, methyl-2-carbomethoxy 3 (paramethoxy) acrylate, and the like.

Examples of quencher (metal complex salt) ultraviolet absorbers include nickel [2,2thiobis (4-t-octyl) phenolate] normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate, and the like.
As HALS (hindered amine) -based 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) Propionyloxy] -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.

  The photoreceptor of the present invention is thus resistant to abrasion by forming a photosensitive layer and a protective layer on a conductive substrate, and optionally forming an undercoat layer and an intermediate layer, and adding a filler to the protective layer. And improved durability.

  The present invention relates to a cleaning blade mounted on a cleaning unit in an image forming method and apparatus, and a corrugated plate-like or triangular wave-like repeated shape substantially at right angles to the abutting side in at least the cut surface shape of the tip contacting the photoconductor Further, in the repetitive shape, the uneven height is 10 μm to 15 μm and the uneven pitch is 10 μm to 20 μm, so that the blade wear caused by the deformation is reduced in the cleaning of the small particle size and spherical toner, Good cleaning properties can be maintained over time.

As a method of forming such a repetitive shape of the blade cut surface, after forming a urethane sheet by centrifugal molding, it is cut by a straight cutter of a predetermined width when cutting into a strip shape, and the shape of the blade of the cutter Can be processed into a corrugated plate shape or a triangular wave shape. For example, an excimer laser can be used to process the blade, and the processing can be performed with a minimum processing dimension of 2 μm.

Subsequently, an image forming method and an image forming apparatus of the present invention will be described.
FIGS. 3 and 4 are schematic views of the elastic blade used in the present invention and its cut surface shape, each having a corrugated plate shape and a triangular wave shape cut surface repeating shape.
FIG. 5 is a schematic view showing an image forming method and an image forming apparatus of the present invention.
The photoconductor (6) has a drum shape, but may be a sheet or an endless belt.

Around the photoreceptor (6), a pre-transfer charger (7), a transfer charger, a separation charger, and a pre-cleaning charger (8) are arranged as necessary, and corotron, scorotron, solid state charger (solid state Charger) and known means such as a charging roller are arranged.
The charging member (9) may be in contact with the photosensitive member. However, by providing an adjacent gap with an appropriate gap (about 10 to 200 μm) between them, the wear amount of both can be reduced and the charging member Toner filming can be suppressed and can be preferably used.

The voltage applied to the charging member (9) is effective when the AC component is superimposed on the DC component in order to stabilize charging and suppress charging unevenness.
As the transfer means, the above-mentioned charger can be generally used, but those using a transfer belt (10) as shown in FIG. 5 are effective.
Further, light sources such as the image exposure unit (11) and the charge removal lamp (12) include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), electroluminescence (EL). ) And other luminescent materials can be used.

Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
These light sources are used not only for the process shown in FIG. 5 but also for a transfer process, a static elimination process, a cleaning process, a pre-exposure process and the like using light irradiation, and irradiate the photoreceptor (6) with light.

The toner developed on the photosensitive member (6) by the developing unit (13) is transferred to the transfer paper (14), but not all is transferred, and the toner remaining on the photosensitive member (6) is also transferred. The toner is removed from the photoreceptor (6) by the fur brush (15) and the cleaning blade (16).
Although cleaning may be performed only with a cleaning blade, a cleaning brush such as a fur brush may be used in combination with the cleaning blade of the present invention.

When the electrophotographic photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member.
If this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and if developed with positive (negative) polarity toner, a negative image can be obtained.
A known method is applied to the developing unit, and a known method is also used as the charge eliminating unit.
In FIG. 5, (17) is a registration roller, and (18) is a separation claw.
The present invention is an image forming method and an image forming apparatus using an electrophotographic photosensitive member for such image forming means.

The image forming unit may be fixedly incorporated in a copying apparatus, a facsimile machine, or a printer, but may be incorporated in these apparatuses and made detachable in the form of a process cartridge.
Here, the process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit.

Accordingly, the present invention also provides a process cartridge for an image forming apparatus having at least charging, image exposure, development, transfer, fixing, and cleaning means, comprising the electrophotographic photosensitive member and a cleaning blade. A process cartridge for a forming apparatus is also provided.
FIG. 6 is a schematic view showing an example of a process cartridge for an image forming apparatus according to the present invention. For example, as shown in FIG. 6, the process cartridge for an image forming apparatus of the present invention incorporates a photoreceptor 101 (drum type), and includes a contact-type charging unit 102, an exposure unit 103, a developing unit 104, and a cleaning blade 107. In addition, it has other members as required. For example, the transfer unit 106, the charge removal lamp 108, the fixing unit 109, and the like may be integrated. Here, as the photosensitive member 101, the same one as the above-described image forming apparatus can be used. As the charging means 102, an arbitrary charging member is used. Further, as the exposure means 103, a light source capable of writing with high resolution is used. The process cartridge for an image forming apparatus of the present invention may be configured to be detachable using guide means such as a rail of the apparatus main body.

  According to the present invention, it can be preferably applied to a high-endurance digital high-speed electrophotographic process using a laser beam as a writing light source, which has become the mainstream in recent years, and suppresses deterioration of the cleaning blade with respect to a small particle size, spherical toner, and poor cleaning. It is possible to ensure a good cleaning property without generating odor, excellent wear resistance for the photoreceptor, extremely little deterioration of the photoreceptor such as filming, and stable and excellent image for high-definition electrophotographic process. An image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus can be provided.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited at all by these Examples. All parts are parts by weight.
(Production of urethane sheet for evaluation blade)
As a urethane rubber sheet for an evaluation blade, a 2 mm thick urethane sheet was prepared by the following composition. As a sheet molding procedure, the prepolymer is first heated and melted at 90 degrees, a curing agent is added thereto, and the mixture is stirred for 1 minute with a reciprocating rotary stirrer agitator (manufactured by Shimazaki Seisakusho Co., Ltd.). Defoaming was performed for 1 minute and the mixture was poured into a mold. The primary firing was performed at 150 ° C. for 1 hour, the secondary firing was performed at 120 ° C. for 12 hours, and curing was further performed at 23 ° C. and 50% RH for 7 days.

(Formulation 1)
Polyethylene adipate prepolymer (isocyanate: MDI)
Curing agent: 1,4BD / TMP = 85/15 wt%
α value: 0.9
(Formulation 2)
Polycaprolactone-based prepolymer (isocyanate: MDI)
Curing agent: 1,4BD / TMP = 90/10 wt%
α value: 0.9
(Formulation 3)
Polycaprolactone-based prepolymer (isocyanate: MDI)
Curing agent: 1,4BD / TMP = 90/10 wt%
α value: 0.85
(Formulation 4)
Polyethylene adipate prepolymer (isocyanate: MDI)
Curing agent: 1,4BD / TMP = 80/20 wt%
α value: 0.8
(Formulation 5)
Polyethylene adipate prepolymer (isocyanate: NDI)
Curing agent: 1,4BD / TMP = 85/15 wt%
α value: 0.85

The hardness and rebound resilience of the urethane rubber sheet by the above blending were as follows at 25 ° C.
(Formulation 1) Hardness 67 degrees, rebound resilience 50%
(Formulation 2) Hardness 75 degrees, rebound resilience 68%
(Formulation 3) Hardness 72 degrees, rebound resilience 60%
(Formulation 4) Hardness 65 degrees, rebound resilience 45%
(Formulation 5) Hardness 80 degrees, rebound resilience 35%

(Blade strip production)
Cutting blades having the following shapes were prepared in advance by laser processing, and each was cut into strips to produce blade urethane rubber parts.
The repeated shape of the cutting blade is the same in size and shape.

(Shape 1)
Cutting shape: Corrugated plate Concave and convex height: 10 μm
Uneven pitch: 10 μm
(Shape 2)
Cutting shape: triangular wave Unevenness height: 10 μm
Uneven pitch: 10 μm
(Shape 3)
Cutting shape: Corrugated plate Concave and convex height: 15 μm
Uneven pitch: 10 μm
(Shape 4)
Cutting shape: Triangular wave Uneven height: 15 μm
Uneven pitch: 20 μm
(Shape 5)
Shape at cutting: Corrugated shape Unevenness height: 25 μm
Uneven pitch: 20 μm
(Shape 6)
Cutting shape: Corrugated plate Concave and convex height: 10 μm
Uneven pitch: 35 μm
(Shape 7)
Cutting shape: Straight Uneven height: 2 μm or less Uneven pitch: None

Cutting was performed with the above cutting blades, and they were adhered to a predetermined sheet metal holder to complete an evaluation cleaning blade.
Evaluation of the cleaning property was carried out by mounting the prototype blade on a color composite machine “image Neo Neo C455” manufactured by Ricoh. (The prototype blade has the same shape and dimensions as the standard blade)

(Evaluation toner)
A toner prepared by a polymerization method was used.
Toner base: circularity 0.98, volume average particle size 4.9 μm
External additive: 1.5 parts of small particle size silica (Clariant H2000)
0.5 parts small particle size titanium oxide (Taika MT-150AI)
1.0 parts of large particle size silica (UFP-30H manufactured by Denki Kagaku Kogyo)
(Blade contact condition)
Linear pressure: 20 g / cm
Cleaning angle: 78 degrees (evaluation environment)
20 ° C 65% RH
(Conditions for passing paper)
Yield 5% chart 10,000 prints with 3 prints / job (A4 width)
(Evaluation item)
Occurrence of cleaning failure: Existence (visual observation of 5% chart output)
Blade edge wear width: Wear width seen from the blade mirror side
Measured with an ultra-deep shape measuring microscope VK8500 (manufactured by Keyence Corporation)

(Evaluation results)
(Example 1)
Urethane rubber formulation: Formula 1
Cut surface shape: Shape 1
Occurrence of cleaning failure: None Blade edge wear width: 3.7 μm
(Example 2)
Urethane rubber compounding: compounding 3
Cut surface shape: Shape 2
Occurrence of defective cleaning: None Blade edge wear width: 3.2 μm
(Example 3)
Urethane rubber compounding: compounding 2
Cut surface shape: Shape 3
Occurrence of cleaning failure: None Blade edge wear width: 3.5 μm

Example 4
Urethane rubber compounding: compounding 2
Cut surface shape: Shape 4
Occurrence of poor cleaning: None Blade edge wear width: 3.9 μm
(Comparative Example 1)
Urethane rubber compounding: compounding 3
Cut surface shape: Shape 5
Occurrence of poor cleaning: No occurrence of belt-like chestnut Blade edge wear width: 6.2 μm
(Example 5)
Urethane rubber compounding: compounding 3
Cut surface shape: Shape 3
Occurrence of cleaning failure: None Blade edge wear width: 2.8 μm
(Comparative Example 2)
Urethane rubber compounding: compounding 4
Cut surface shape: Shape 6
Occurrence of poor cleaning: None Blade edge wear width: 8.5 μm
(Comparative Example 3)
Urethane rubber blend: Blend 5
Cut surface shape: Shape 7
Occurrence of cleaning failure: No occurrence of belt-like chestnut Blade edge wear width: 11.5 μm

(Example 6)
Urethane rubber compounding: compounding 2
Cut surface shape: Shape 1
Occurrence of cleaning failure: None Blade edge wear width: 3.3 μm
(Example 7)
Urethane rubber formulation: Formula 1
Cut surface shape: Shape 4
Occurrence of cleaning failure: None Blade edge wear width: 4.1 μm
(Comparative Example 4)
Urethane rubber compounding: compounding 3
Cut surface shape: Shape 7
Occurrence of cleaning failure: No occurrence of belt-like chestnut Blade edge wear width: 9.8 μm

(Comparative Example 5)
Urethane rubber blend: Blend 5
Cut surface shape: Shape 1
Occurrence of cleaning failure: No occurrence of streak-like chestnut Blade edge wear width: 5.5 μm
(Example 8)
Urethane rubber compounding: compounding 2
Cut surface shape: Shape 2
Occurrence of cleaning failure: None Blade edge wear width: 4.3 μm
(Comparative Example 6)
The blade edge shown in Comparative Example 4 was roughened by the following method.
A lapping film sheet # 600 (manufactured by Sumitomo 3M Limited) was used and polished for 1 minute while being brought into contact with the blade edge portion at a linear pressure of 25 g / cm.
Occurrence of cleaning failure: No occurrence of streak-like chestnut Blade edge wear width: 21.5 μm

1 is a schematic cross-sectional view of a multilayer electrophotographic photosensitive member used in the present invention. It is a schematic sectional drawing of the other laminated electrophotographic photosensitive member used for this invention. It is the schematic of the braid | blade used for this invention, and its cut surface shape. It is the schematic of the other braid | blade used for this invention, and its cut surface shape. 1 is a schematic view showing an image forming method and an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge for an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 3 Charge generation layer 4 Charge transport layer 5 Protective layer 6 Photoconductor 7 Charger before transfer 8 Charger before cleaning 9 Charging member

DESCRIPTION OF SYMBOLS 10 Transfer belt 11 Image exposure part 12 Static elimination lamp 13 Developing unit 14 Transfer paper 15 Fur brush 16 Cleaning blade 17 Registration roller 18 Separation nail

101 photoconductor (drum type)
102 Charging means (contact type)
103 Exposure means 104 Development means 105 Transfer paper 106 Transfer means (contact type)
107 Cleaning blade 108 Static elimination lamp 109 Fixing means

Claims (13)

In an image forming method in which charging, image exposure, development, transfer, and cleaning processes are performed on at least a photoconductor, a cleaning unit that performs the cleaning process includes an elastic blade, and a portion of the elastic blade that is in contact with the photoconductor An image forming method, wherein a contact cut surface is formed, and the corresponding contact cut surface has a corrugated plate shape or a triangular wave shape at a substantially right angle to the contact side. 2. The image forming method according to claim 1, wherein the repetitive shape of the contact cut surface with the photosensitive member in the elastic blade has an uneven height of 10 μm to 15 μm and an uneven pitch of 10 μm to 20 μm. 3. The image formation according to claim 1, wherein the elastic blade is made of urethane rubber and has a hardness of 67 to 75 degrees (JIS A) at 25 ° C. and a rebound resilience of 50 to 68%. Method. 4. The image forming method according to claim 1, wherein the photosensitive member has a protective layer, and the protective layer contains inorganic fine particles made of alumina or titanium oxide. The image forming method according to claim 4, wherein the photoconductor protective layer contains a charge transport material. The image forming method according to claim 1, wherein the toner used in the development processing has a volume average particle size of 5.5 μm or less and a circularity of 0.97 or more. In an image forming apparatus having at least a photosensitive member, a charging unit, an image exposing unit, a developing unit, a transferring unit, and a cleaning unit, a cleaning unit for performing a cleaning process has an elastic blade and is in contact with the photosensitive member of the elastic blade. An image forming apparatus, wherein a contact cut surface is formed in a portion, and the contact cut surface has a corrugated or triangular wave repetitive shape substantially perpendicular to the contact side. 8. The image forming apparatus according to claim 7, wherein the repetitive shape of the contact cut surface with the photosensitive member in the elastic blade has an uneven height of 10 μm to 15 μm and an uneven pitch of 10 μm to 20 μm. 9. The image formation according to claim 7, wherein the elastic blade is made of urethane rubber, and has a hardness of 67 to 75 degrees (JIS A) at 25 ° C. and a rebound resilience of 50 to 68%. apparatus. The image forming apparatus according to claim 7, wherein the photoconductor has a protective layer, and the protective layer contains inorganic fine particles made of alumina or titanium oxide. The image forming apparatus according to claim 10, wherein the photoconductor protective layer contains a charge transport material. The image forming apparatus according to claim 7, wherein the toner used in the developing unit has a volume average particle size of 5.5 μm or less and a circularity of 0.97 or more. A cleaning unit comprising an elastic blade having a repeated shape of at least a contact cut surface, which is used in the image forming method according to any one of claims 1 to 6 or the image forming apparatus according to any one of claims 7 to 12. A process cartridge for an image forming apparatus, comprising:

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