JP4227555B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method used in a recording method using an electrophotographic method, an electrostatic recording method or the like. More specifically, the present invention relates to an image forming method used in a copying machine, a printer, and a fax machine in which an electrostatic latent image formed on an electrostatic latent image carrier is developed with toner and then transferred onto a transfer material to form an image. It is.

  In an image forming method used for an electrophotographic apparatus, an electrostatic recording apparatus, and the like, various methods are known as a method for forming a latent image on a photosensitive member such as an electrophotographic photosensitive member or an electrostatic recording dielectric.

  For example, in electrophotography, an electrical latent image is formed by uniformly charging a photoconductor using a photoconductive material as a latent photoconductor to the required polarity and potential, and then performing image pattern exposure. In general, the toner is developed and visualized, and this is transferred and fixed to a transfer medium such as paper.

  In recent years, charging devices that come into contact with a photoreceptor capable of achieving low ozone and low power have been put into practical use.

  However, the amount of scraping on the surface of the image carrier is large due to the narrow discharge near the contact portion, and since it is a contact type, the surface of the charging member becomes dirty and an image abnormality tends to occur. Further, since the charging member is made of conductive resin rubber, there is a drawback that the life of the charging member itself is shorter than that of the corona charger due to deterioration of the material due to discharge and fluctuation of resistance. Particularly in recent years, in order to respond to environmental problems such as dust generated by cartridge disposal and strong demands for cost reduction, it is inevitably necessary to extend the life of the photoreceptor as an image carrier, and the amount of abrasion of the photoreceptor is reduced. Fewer corona chargers are reviewed again.

  On the other hand, an electrophotographic photoreceptor is often used as a function-separated photoreceptor in which a charge generation layer and a charge transport layer are laminated in order to satisfy both electrical and mechanical properties. As a matter of course, the electrophotographic photosensitive member is required to have sensitivity, electrical characteristics, and optical characteristics according to the applied electrophotographic process. In particular, since various electrical and mechanical external forces such as charging, image exposure, toner development, transfer to paper, and cleaning are directly applied to the surface of the photoreceptor to be used repeatedly, durability against them is required.

  Specifically, durability against the occurrence of surface abrasion and scratches due to rubbing, and durability against deterioration of electrical characteristics such as sensitivity reduction and potential reduction are also required.

  Solving such problems of the conventional electrophotographic photosensitive member, and improving the abrasion resistance and scratch resistance by increasing the film strength, and further, in the case of repeated use, A photoconductor containing a curable resin in the surface layer is used as an electrophotographic photoconductor that exhibits very little change in characteristics and deterioration of the photoconductor such as an increase in residual potential and can exhibit stable performance even when used repeatedly. This has been proposed (see, for example, Patent Document 1).

  However, especially when used in a high humidity environment or in a machine with a high process speed, these highly wear-resistant photoconductors have little abrasion of the photoconductor, so that charged products adhering to the surface are, for example, Since it is difficult to remove the surface of the photoconductor with a cleaning blade or the like, it cannot be completely removed.

  These problems are improved by adding particles having an abrasive action to the toner and stripping off the charged product adhering to the surface of the photoreceptor as described above. However, conventionally used abrasive particles have a large particle size and a broad particle size distribution, so it is necessary to add a large amount to the toner in order to uniformly polish the surface of the photoreceptor. Problems such as scattering, reversal fogging, and accumulation of abrasive particles were likely to occur. As an improvement of this point, strontium titanate with a small particle size and reduced sparse grains is proposed, and there is also a proposal of an inorganic fine powder having an excellent polishing effect when added in a small amount (see, for example, Patent Document 2). ).

JP 2002-82469 A Japanese Patent Laid-Open No. 10-10770

  We have proposed an inorganic fine powder that has an excellent polishing effect by adding a small amount of strontium titanate with a small particle size and reduced looseness. However, when used in a high humidity environment, the photoconductor has high wear resistance. Was used to remove the charged product.

  In addition, when using a photoconductor with high wear resistance, when performing blade cleaning in the cleaning process of the transfer residual toner, it is difficult to remove the charged product, so that the slipperiness of the surface of the photoconductor deteriorates and the blade is It is easy to chatter, and the abrasive particles with fine particle size are easy to slip through, and when the rubber behavior of the photoconductor acts here, foreign particles such as toner particles and paper dust are pinched between the cleaning blade and the drum. This also causes a problem that the scratches are generated and the life of the photosensitive member is deteriorated due to local scratches caused by slipping rather than the wear of the front surface of the photosensitive member. Furthermore, the accumulation of discharge products deteriorates the slip of the photoconductor, and the inorganic fine powder such as abrasive particles slips through, so that no particles stay in the vicinity of the blade, thereby lubricating the blade and the photoconductor. However, the blade is curled or the load on the blade is increased due to the deterioration of the slipperiness, the blade is chipped or the blade itself is scraped, and there is a tendency that an image defect due to slipping eventually occurs.

  Further, when a photoconductor having high wear resistance was charged by corona discharge, white streaks in which the circumferential direction was whitened were generated in a halftone image. This is probably because an external additive or the like adheres to the photoconductor to reduce the surface resistance and cause image flow in the drum circumferential direction.

  Accordingly, an object of the present invention is to provide an image forming method that solves the above-described problems. Specifically, in the process of using a photoconductor with high wear resistance and removing the residual toner from the photoconductor, even if blade cleaning, which is a simple cleaning configuration, is used, deposits that cause white streaks In other words, it is possible to suppress damage to the photoreceptor and the load on the blade, and to prevent contamination of the corona charger due to toner scattering. Furthermore, the present invention provides a highly durable image forming method even when used in a machine with a high humidity environment and a high process speed.

  The above object can be achieved by an image forming method characterized by the following constitution of the present invention.

(1) a step of charging a photosensitive member having a photosensitive layer and a protective layer on a support as an image carrier by corona discharge, an electrostatic latent image forming step of forming an electrostatic latent image on the charged photosensitive member; A development process in which the toner carried on the toner carrying member is transferred to the electrostatic latent image for visualization, and the toner image formed on the image carrying member is transferred with or without the intermediate transfer member. In an image forming method comprising at least a transfer step of transferring to a material, and a cleaning step of removing transfer residual toner remaining on the photoconductor from the photoconductor after the transfer step,
The surface of the protective layer of the photoconductor is subjected to a hardness test using a Vickers square pyramid diamond indenter in an environment of 25 ° C. and a humidity of 50%, and the HU (Universal Hardness Value) when pressed at a maximum load of 6 mN is 150 or more. 240 or less (N / mm ² ), and the elastic deformation rate is 44% or more and 65% or less,
The toner has colored particles containing at least a binder resin and a colorant;
Further, at least the toner has an inorganic fine powder of perovskite crystal in which the average particle size of primary particles is 30 nm or more and 120 nm or less and the number of particles having an aggregate particle size of 600 nm or more is 0.5 % by number or less. On the other hand, 0.2 mass% or more and 4 mass% or less are externally added,
The inorganic fine powder contains 65% by number or more whose primary particle shape is approximately cubic or rectangular parallelepiped,
The liberation rate of the inorganic fine powder in the toner is 13 to 32% by volume,
The inorganic fine powder is strontium titanate or barium titanate,
An image forming method, wherein a transfer residual toner remaining on a photoconductor after the transfer step is removed from the photoconductor by a cleaning blade in which the inorganic fine powder stays.
( 2 ) The image forming method according to (1 ), wherein the inorganic fine powder is subjected to a surface treatment.
( 3 ) The image forming method according to (1) or (2) , wherein the toner is a magnetic toner containing a magnetic substance.
( 4 ) The image forming method according to any one of (1) to ( 3 ), wherein the protective layer of the photoreceptor is a protective layer formed of a curable resin containing a charge transport material.
( 5 ) The protective layer of the photoreceptor is formed by irradiation with radiation, and the protective layer formed by irradiation with radiation polymerizes or crosslinks a compound having a chain polymerizable functional group. The image forming method according to any one of (1) to ( 4 ), which is a cured layer.
( 6 ) The image forming method according to any one of (1) to ( 5 ), wherein the charging means by corona discharge on the photoconductor is a scorotron type corona charger having a discharge wire and a grid in a shield.

According to the present invention, a step of charging a photoconductor having a photosensitive layer and a protective layer on at least a support as an image carrier by corona discharge, an electrostatic latent image for forming an electrostatic latent image on the charged photoconductor. An image forming step, a developing step of transferring the toner carried on the toner carrying member to the electrostatic latent image for visualization, and a toner image formed on the image carrying member via the intermediate transfer member or via In addition, in the image forming method including a transfer step of transferring to a transfer material, and a cleaning step of removing transfer residual toner remaining on the photoconductor from the photoconductor after the transfer step, the surface of the protective layer of the photoconductor is 25 ° C. , HU (universal hardness value) is 150 to 240 (N / mm ² ) when a hardness test is performed using a Vickers square pyramid diamond indenter in an environment of 50% humidity and the maximum load is 6 mN. Or An image bearing member having an elastic deformation ratio of 44% or more and 65% or less, wherein the toner contains at least a binder resin and a colorant, and the toner has an average primary particle diameter of 30 nm or more and 170 nm or less. In addition, an image forming method characterized in that an inorganic fine powder of a perovskite crystal having an aggregate particle size of 600 nm or more is 1% by number or less is externally added. Even when a drum is used, it is possible to satisfactorily scrape discharge products and the like adhering to the drum surface with the cleaning blade portion, and as a result, the slipperiness of the drum surface is ensured. In addition, since white streaks, drum scratches, and poor charging are suppressed, it is possible to provide a highly durable image forming method with a simpler configuration.

  Next, the image forming method of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of a specific apparatus that can be used to carry out the image forming method of the present invention.

  In FIG. 1, reference numeral 1 denotes a photosensitive drum, around which a corona charger 6, a developing device 7, and a transfer charging roller 8 are provided. The photoreceptor 1 is charged by a corona charger 6. And it exposes by irradiating the photoreceptor 1 with the laser beam L with a laser generator. The electrostatic latent image on the photoconductor 1 is developed with toner by the developing unit 7 and transferred onto the transfer material 1 by the transfer roller 8 in contact with the photoconductor via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 3 through the conveyance guide and is fixed on the transfer material. Further, in this image forming method, toner partially remaining on the photoconductor is removed from the surface of the photoconductor by the cleaning elastic blade 4 that contacts the photoconductor.

A feature of the present invention is that the photoreceptor 1 shown in FIG. 1 has a protective layer having a universal hardness value HU of 150 to 240 (N / mm ² ) and an elastic deformation ratio of 44% to 65%. In addition, the toner contains at least a binder resin and a colorant, and at least primary particles having an approximately cubic or rectangular parallelepiped shape have an average particle diameter of 30 nm to 170 nm and an aggregate having a particle diameter of 600 nm or more. It is that the inorganic fine powder of the perovskite type crystal | crystallization which is 1 number% or less was contained.

[Photoconductor production method]
Hardness test is performed using a Vickers square pyramid diamond indenter in an environment where the surface used in the present invention is 25 ° C. and a humidity of 50%, and HU (universal hardness value) when pressed at a maximum load of 6 mN is 150 N / mm ² or more. An electrophotographic photosensitive member having a high durability of 240 N / mm ² or less and having an elastic deformation rate of 44% or more and 65% or less will be described in detail including the production method.

  The electrophotographic photoreceptor of the present invention preferably has mainly a laminated structure. In the electrophotographic photosensitive member, a charge generation layer and a charge transport layer are sequentially provided on a support, and a protective layer is further provided on the outermost surface. Further, a binder layer and an undercoat layer for the purpose of preventing interference fringes may be provided between the support and the charge generation layer.

  The support itself can be conductive, for example, aluminum, aluminum alloy, or stainless steel. In addition, aluminum, aluminum alloy, or indium oxide-tin oxide alloy is formed by vacuum deposition. The support having the layer formed, the plastic, the conductive fine particles (for example, carbon black, tin oxide, titanium oxide, silver particles, etc.) and the appropriate support resin impregnated into the plastic or paper, the conductive binder A plastic having a resin can be used.

  Further, a binder layer (adhesive layer) having a barrier function and an adhesive function can be provided between the support and the photosensitive layer. The binder layer is used to improve the adhesion of the photosensitive layer, improve the coatability, protect the support, cover defects on the support, improve the charge injection from the support, and protect against electrical breakdown of the photosensitive layer. It is formed. The binder layer can be formed of casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The film thickness of the binder layer is preferably 5 μm or less, and particularly preferably 0.1 to 3 μm.

  Examples of the charge generating substance used in the present invention include (1) azo pigments such as monoazo, disazo and trisazo, (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, and (3) indigo compounds such as indigo and thioindigo. Pigments, (4) perylene pigments such as perylene anhydride and perylene imide, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, (6) squarylium dyes, (7) pyrylium salts and thiapyrylium salts, ( 8) Triphenylmethane dyes, (9) inorganic substances such as selenium, selenium-tellurium and amorphous silicon, (10) quinacridone pigments, (11) azulenium salt pigments, (12) cyanine dyes, (13) xanthene dyes, 14) Quinone imine dye, (15) Su Lil dyes, and (16) cadmium sulfide and (17) zinc oxide.

  Examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples thereof include, but are not limited to, silicone resins, polysulfone resins, styrene-butadiene copolymer resins, alkyd resins, epoxy resins, urea resins, and vinyl chloride-vinyl acetate copolymer resins. These can be used alone or as a mixture or as a copolymer polymer.

  The solvent used for the charge generation layer coating is selected from the solubility and dispersion stability of the resin used and the charge generation material, but examples of the organic solvent include alcohols, sulfoxides, ketones, ethers, esters, Aliphatic halogenated hydrocarbons or aromatic compounds can be used.

  The charge generation layer is well dispersed by a method such as a homogenizer, ultrasonic wave, ball mill, sand mill, attritor or roll mill, together with a binder resin and a solvent in an amount of 0.3 to 4 times the mass of the charge generation material, It is formed by coating and drying. The thickness is preferably 5 μm or less, and particularly preferably in the range of 0.01 to 1 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and known charge generating substances can be added to the charge generation layer as necessary.

  The charge transport materials used include various triarylamine compounds, various hydrazone compounds, various styryl compounds, various stilbene compounds, various pyrazoline compounds, various oxazole compounds, various thiazole compounds, and various triarylmethane compounds. Compound etc. are mentioned.

  Examples of the binder resin used for forming the charge transport layer include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. The resin chosen is preferred. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin and diallyl phthalate resin.

  The charge transport layer is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio (mass ratio) of the charge transport material and the binder resin is about 2: 1 to 1: 2. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride, tetrahydrofuran, Ethers such as dioxane are used. When this solution is applied, for example, a coating method such as a dip coating method, a spray coating method and a spinner coating method can be used, and drying is preferably 10 ° C to 200 ° C, more preferably 20 ° C to 150 ° C. The temperature is in the range of 5 minutes to 5 hours, and more preferably 10 minutes to 2 hours.

  The charge transport layer is electrically connected to the above-described charge generation layer, receives charge carriers injected from the charge generation layer in the presence of an electric field, and transports these charge carriers to the interface with the protective layer. It has a function. Since this charge transport layer has a limit to transport charge carriers, the film thickness cannot be increased more than necessary, but it is preferably 5 to 40 μm, and particularly preferably 7 to 30 μm.

  Furthermore, an antioxidant, an ultraviolet absorber, a plasticizer, and a known charge transport material can be added to the charge transport layer as necessary.

Furthermore, in the present invention, the protective layer is applied and cured on the charge transport layer to form a film, and a hardness test is performed using a Vickers square pyramid diamond indenter in an environment having a surface of 25 ° C. and a humidity of 50%. And a photosensitive member having a HU (Universal Hardness Value) of 150 N / mm ² or more and 240 N / mm ² or less when pressed with a maximum load of 6 mN and an elastic deformation ratio of 44% or more and 65% or less is completed. .

  As a protective layer for an electrophotographic photoreceptor satisfying the above conditions, a compound obtained by polymerizing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule as represented by the following general formula (1) There is a protective layer to do.

式中、Ａは正孔輸送性基を示す。Ｐ¹及びＰ²は連鎖重合性官能基を示す。Ｐ¹とＰ²は同一でも異なってもよい。Ｚは置換基を有してもよい有機残基を示す。ａ、ｂ及びｄは０又は１以上の整数を示し、ａ＋ｂ×ｄは２以上の整数を示す。また、ａが２以上の場合Ｐ¹は同一でも異なってもよく、ｄが２以上の場合Ｐ²は同一でも異なってもよく、またｂが２以上の場合、Ｚ及びＰ²は同一でも異なってもよい。

In the formula, A represents a hole transporting group. P ¹ and P ^{2 each} represent a chain polymerizable functional group. P ¹ and P ² may be the same or different. Z represents an organic residue which may have a substituent. a, b, and d represent 0 or an integer of 1 or more, and a + b × d represents an integer of 2 or more. When a is 2 or more, P ¹ may be the same or different. When d is 2 or more, P ² may be the same or different. When b is 2 or more, Z and P ² are the same or different. May be.

  By polymerizing a hole transporting compound having two or more chain-polymerizable functional groups in the same molecule, the compound having a hole transporting ability in the protective layer has at least two or more crosslinking points. It is incorporated into the dimensional cross-linked structure via a covalent bond. The hole transporting compound can be either polymerized alone or mixed with a compound having another chain polymerizable group, and the kind / ratio is arbitrary. As used herein, the compound having another chain polymerizable group includes any monomer or oligomer / polymer having a chain polymerizable group. When the functional group of the hole transporting compound and the functional group of the other chain polymerizable compound are the same group or a group that can be polymerized with each other, they both take a copolymerized three-dimensional crosslinked structure via a covalent bond. Is possible. When both functional groups are functional groups that do not polymerize with each other, the photosensitive layer is a mixture of at least two or more three-dimensional cured products or other chain-polymerizable compound monomers in the three-dimensional cured product as a main component. Although it is comprised as the thing containing the hardened | cured material, it is also possible to form an IPN (Inter Penetrating Network), ie, an interpenetrating network structure, by controlling the compounding ratio / film forming method well.

  In the present invention, the protective layer contains at least one selected from the group consisting of fluorine atom-containing resin, carbon fluoride, and polyolefin resin as a lubricant, and preferred compounds include the following. However, it is not limited to these compounds.

  Preferred as the fluorine atom-containing resin is a polymer or copolymer resin of a compound selected from vinyl fluoride, vinylidene fluoride, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoropropylene, perfluoroalkyl vinyl ether, and Examples include resin fine particles.

Examples of the carbon fluoride include compounds represented by (CF) n and (C ₂ F) n.

  Preferred examples of the polyolefin resin include homopolymer resins such as polyethylene resin, polypropylene resin and polybutene resin, copolymer resins such as ethylene-propylene copolymer and ethylene-butene copolymer, and resin powder.

  These lubricants can be used alone or in combination of two or more at any ratio.

  The protective layer may contain a dispersant for the lubricant, a dispersion aid, other various additives, a surfactant, and the like.

  By containing at least one of fluorine atom-containing resin, carbon fluoride, and polyolefin resin as a lubricant in the protective layer, the surface slipperiness and water repellency of the photoreceptor can be improved, and charging during repeated use, Deterioration of transfer efficiency and slipperiness due to chemical deterioration of the surface layer due to development, transfer, etc., and further deterioration of electrical properties such as sensitivity reduction and potential reduction are prevented. Filming, fusing, and cleaning failure even during repeated use It is possible to suppress the occurrence of image defects such as image blur / flow. Particularly preferable results are obtained when the fluorine-containing resin is used.

  In the present invention, the ratio of the lubricant contained in the protective layer is preferably 1 to 50%, more preferably 5 to 40%, based on the total weight of the layer to be the surface layer. When the amount of the lubricant is more than 50%, the mechanical strength of the layer serving as the surface layer tends to be lowered, and when it is less than 1%, the water repellency and slipperiness of the layer serving as the surface layer may not be sufficient.

  In the present invention, a charge transport material can be contained in the protective layer containing the cured product of the hole transporting compound having the chain polymerizable group.

  The protective layer is generally formed by applying a solution containing the hole transporting compound and then carrying out a polymerization reaction, but a cured product obtained by reacting a solution containing the hole transporting compound in advance. After obtaining the above, it is possible to form a protective layer by dispersing or dissolving in the solvent again. As a method for applying these solutions, for example, a dip coating method, a spray coating method, a curtain coating method, a spin coating method, and the like are known, but the dip coating method is preferable from the viewpoint of efficiency / productivity.

  In the present invention, the hole transporting compound having a chain polymerizable group is preferably polymerized by radiation. The greatest advantage of polymerization by radiation is that a polymerization initiator is not required, which makes it possible to produce a very high-purity three-dimensional photosensitive layer and to ensure good electrophotographic characteristics. In addition, because it is a short and efficient polymerization reaction, it is highly productive, and because of its high radiation permeability, it inhibits curing when thick films and additives such as additives are present in the film. The influence of the is very small. However, depending on the type of the chain polymerizable group and the type of the central skeleton, the polymerization reaction may not easily proceed, and in this case, it is possible to add a polymerization initiator within a range that does not affect the reaction. The radiation used at this time is an electron beam and a gamma ray. In the case of electron beam irradiation, any type of accelerator such as a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type can be used. When irradiating with an electron beam, the irradiation conditions are very important in the photoreceptor of the present invention in order to develop electric characteristics and durability. In the present invention, the acceleration voltage is preferably 250 kV or less, and optimally 150 kV or less. The dose is preferably in the range of 10 kGy to 1000 kGy, more preferably in the range of 30 kGy to 500 kGy. When the accelerating voltage exceeds the above, the electron beam irradiation damage tends to increase on the characteristics of the photoreceptor. Further, when the dose is less than the above range, the curing tends to be insufficient, and when the dose is large, the photoreceptor characteristics are likely to deteriorate.

A photoreceptor having a surface layer containing a hole transport compound obtained by polymerizing a compound having an unsaturated functional group in the molecule, produced as described above, has a universal hardness value (hereinafter HU) of 150 to 240 ( N / mm ² ) and an elastic deformation rate of 44% or more and 65% or less, and as shown in Japanese Patent Laid-Open No. 2001-166509, an electrophotographic photosensitive member using a conventional resin as a surface layer has The above problems have been solved, the film strength is increased to improve the wear resistance and scratch resistance, and the precipitation resistance is good. Electrophotographic photoconductor with very little change and deterioration, stable performance even when used repeatedly, improved wear resistance and scratch resistance of the surface layer of the electrophotographic photoconductor, and long life and high image quality It is.

  In general, the hardness of the film is higher as the amount of deformation with respect to external stress is smaller, and it is considered that the electrophotographic photosensitive member having higher pencil hardness or Vickers hardness naturally improves durability against mechanical deterioration. However, it was found that the high hardness obtained by these measurements did not necessarily improve the durability, and the above range was good.

Although the HU and the elastic deformation rate cannot be separated, for example, when the HU exceeds 240 N / mm ² and the elastic deformation rate is less than 44%, the paper dust sandwiched between the cleaning blade, the charging, and the transfer roller As a result, the amount of elastic deformation becomes small even if the elastic deformation rate is high, because the elastic deformation rate is larger than 65%. Since a large pressure is applied to the surface, scratches are likely to occur, and the amount of wear of the photoreceptor increases. Therefore, it is considered that the one with a high HU is not necessarily optimal as the photosensitive member.

Also, when the HU is less than 150 N / mm ² and the elastic deformation rate exceeds 65%, even if the elastic deformation rate is high, the amount of plastic deformation increases, and the paper dust sandwiched between the cleaning blade, the charging, and the transfer roller If the toner or the toner is rubbed, it will be scraped off or fine scratches will occur, resulting in a shortened durability life.

[Photosensitive surface physical property evaluation method]
HU (universal hardness value) and elastic deformation rate are microhardness measuring equipment Fischerscope H100V (Fischer) that can apply continuous load to the indenter and read the indentation depth under the load directly to obtain continuous hardness. The measurement was performed using The indenter used was a Vickers square pyramid diamond indenter with a face angle of 136 °. The load conditions were measured stepwise up to a final load of 6 mN (273 points with a holding time of 0.1 s for each point).

  An outline of the output chart is shown in FIG. 2, and an example of measurement of the electrophotographic photosensitive member of the present invention is shown in FIG. The vertical axis represents the load (mN) and the horizontal axis represents the indentation depth h (μm), which is the result of increasing the load stepwise and applying the load to 6 mN, and then decreasing the load stepwise similarly.

  HU (universal hardness value: hereinafter referred to as HU) is defined by the following formula (1) from the indentation depth under the same load when indented at 6 mN.

The elastic deformation rate is obtained from the work (energy) performed by the indenter on the membrane, that is, the change in energy due to the increase or decrease of the load of the indenter on the membrane, and the value is obtained from the following equation (2). The total work (nW) is represented by the area enclosed by A-B-D-A in FIG. 1, and the elastic deformation work We (nW) is represented by the area enclosed by C-B-D-C. The
Elastic deformation rate = We / Wt × 100 (%) (2)

  When using a highly durable photoconductor as described above in an image forming method using corona charging, the white streaks and the cleaning blade are likely to be damaged due to the influence of adhering substances attached to the surface of the photoconductor. It will be necessary to remove the deposits.

  For that purpose, at least the primary particle having an approximately cubic or rectangular parallelepiped shape has an average particle size of 30 nm to 170 nm and the aggregate particle size of 600 nm or more is 1% by number or less. It is necessary to use a toner containing fine powder.

  As described above, strontium titanate disclosed in Japanese Patent Application Laid-Open No. 10-10770 and Japanese Patent No. 3047900 is manufactured through a sintering process, and the shape of the particles is spherical or nearly polyhedral. Therefore, when using a photoconductor with a small amount of wear, the contact area with the photoconductor is small, and since the shape is nearly spherical, it is easier to slip through the cleaning blade, and it is difficult to stay near the blade. It is assumed that the removal of the charged product is insufficient.

  Therefore, by using inorganic fine powder of a perovskite crystal whose particle shape is approximately cubic or rectangular parallelepiped, the shape is angular, so that it is less likely to slip through the cleaning blade than the nearly spherical polyhedron. Occurrence of image defects due to contamination is suppressed, stays in the vicinity of the blade, increases the contact area with the photoconductor, and the ridgeline of the cube or cuboid comes into contact with the photoconductor, thereby removing and scraping off the adhered matter. It becomes possible to carry out effectively.

  The inorganic fine powder used in the present invention preferably has a perovskite crystal. Among the perovskite inorganic fine powders, more preferable are strontium titanate, barium titanate, and calcium titanate, and among these, strontium titanate is more preferable.

  The inorganic fine powder of the perovskite crystal used in the present invention should have an average primary particle size of 30 nm to 170 nm, and more preferably 40 nm to 150 nm.

  If the average particle size is less than 30 nm, the polishing effect of the particles in the cleaner portion is insufficient, which is not preferable. On the other hand, if it exceeds 170 nm, the damming effect on the cleaning blade is increased, and the lubricating action between the blade and the photoconductor is increased. The decrease causes an increase in the load on the blade, causing a problem that the blade is chipped or worn.

  In addition, the inorganic fine powder does not necessarily exist as primary particles on the surface of the colored particles and may exist as an aggregate. Even in this case, the number of particles having an aggregate particle size of 600 nm or more is 1% by number or less. Preferably there is. When 1% by number or more of aggregates of 600 nm or more are contained, even if the primary particle diameter is less than 170 nm, the photoconductor scratches and blade chipping occur, and the problem of image defects due to toner slippage occurs.

  In addition, about the particle size of the inorganic fine powder in this invention, it measured by measuring 100 particle size from the photograph image | photographed with the magnification of 50,000 times with the electron microscope.

  In addition, it is preferable that the content of the inorganic fine powder of the present invention in which the particle shape is approximately cubic or rectangular parallelepiped is 50% by number or more, because the deposits can be more efficiently removed.

  The schematic cubic and rectangular parallelepiped (dice, cubic shape) shape of the inorganic fine powder shows a shape as shown in a photograph taken with an electron microscope at a magnification of 50,000 times in FIG.

In addition, when the particle size of the inorganic fine powder which is a rough cube or a rectangular parallelepiped is the longest side length (T1) and the shortest side length (S1) in the shape of the fine powder shown in FIG. The particle size of the inorganic fine powder was given by the following formula.
Particle size of inorganic fine powder = (T1 + S1) / 2

  Furthermore, in this invention, it is preferable that the release rate with respect to the colored particle of inorganic fine powder is 30 volume% or less.

  Of the inorganic fine powders used in the present invention, it was confirmed that many of the inorganic fine powders that are separated from the cleaning blade are separated from the colored particles and exist alone.

  Therefore, by setting the liberation rate of the inorganic fine powder to the colored particles to be 30% by volume or less, the inorganic fine powder is more difficult to slip from the cleaning blade, so that it is effective for preventing contamination of the charger due to scattering. It is preferable because the fine powder tends to stay in the vicinity of the blade, and the effect of removing the deposit on the blade portion is increased, and white streaks, blade curling, and blade chipping are effective.

[Toner production method]
A perovskite containing a binder resin and a colorant used in the present invention, and the toner has an average primary particle size of 30 nm to 170 nm and an aggregate particle size of 600 nm or more of 1% by number or less. A toner including an externally added fine inorganic powder of type crystal will be described in detail including the production method.

  The inorganic fine particles of the perovskite crystal used in the present invention include, for example, a strontium hydroxide added to a titania sol dispersion obtained by adjusting the pH of a hydrous titanium oxide slurry obtained by hydrolyzing a titanyl sulfate aqueous solution. And it can synthesize | combine by heating to reaction temperature. By setting the pH of the hydrous titanium oxide slurry to 0.5 to 1.0, a titania sol having good crystallinity and particle size can be obtained.

  For the purpose of removing ions adsorbed on the titania sol particles, it is preferable to add an alkaline substance such as sodium hydroxide to the dispersion of the titania sol. At this time, it is preferable that the pH of the slurry is not 7 or higher so that sodium ions and the like are not adsorbed on the surface of the hydrous titanium oxide. The reaction temperature is preferably about 60 ° C to 100 ° C. In order to obtain a desired particle size distribution, the rate of temperature rise is preferably 30 ° C / hour or less, and the reaction time is preferably 3 to 7 hours. .

  In order to confirm that the crystal structure of the inorganic fine powder is a perovskite type (a face-centered cubic lattice composed of three different elements), it can be confirmed by performing X-ray diffraction measurement.

  Further, the inorganic fine powder is preferably treated on the surface of the fine powder from the viewpoint of controlling the triboelectric charge polarity and the triboelectric charge amount depending on the environment in consideration of development characteristics and preventing drum scratches.

  Examples of the surface treatment agent include a treatment agent such as a coupling agent, silicone oil, and fatty acid metal salt.

  By performing the surface treatment, for example, in the case of a coupling agent that is a compound having a hydrophilic group and a hydrophobic group, the hydrophobic group side becomes the outer side by covering the surface of the inorganic fine powder with the hydrophilic group side. Thus, the fluctuation of the triboelectric charge amount due to the environment can be suppressed, and the triboelectric charge amount can be easily controlled by a coupling agent into which a functional group such as an amino group or fluorine is introduced. Furthermore, by treating the surface with the surface treatment agent as described above, the surface of the inorganic fine powder is reduced to fine particles such as fragments smaller than the free average particle diameter, which cause drum scratches contained in the inorganic fine powder. This is preferable because it has a supporting effect of fixing to the drum, and also has an effect of preventing drum scratches.

  Further, in the case of the surface treatment agent as described above, the shape of the inorganic fine powder is hardly changed due to the surface treatment at the molecular level, and the scraping force by the shape of a roughly cubic or rectangular parallelepiped is maintained. preferable.

  Examples of coupling agents include titanate, aluminum, and silane coupling agents. Examples of fatty acid metal salts include zinc stearate, sodium stearate, calcium stearate, zinc laurate, aluminum stearate, and magnesium stearate. The same effect can be obtained with stearic acid, which is a fatty acid.

  The treatment method includes dissolving and dispersing the surface treatment agent to be treated in a solvent, adding an inorganic fine powder therein, removing the solvent with stirring, a wet method, a coupling agent, and a fatty acid metal. Examples thereof include a dry method in which a salt and an inorganic fine powder are directly mixed and treated with stirring.

  Further, regarding the surface treatment, it is not necessary to completely treat and coat the inorganic fine powder, and the inorganic fine powder may be exposed as long as the effect is obtained. That is, the surface treatment may be formed discontinuously.

  In the present invention, the amount of the perovskite inorganic fine powder added to the colored particles is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.2% by mass or more and 4% by mass or less.

  The method for producing the toner of the present invention is not particularly limited, and a suspension polymerization method, an emulsion polymerization method, an association polymerization method, a kneading and pulverization method, and the like are used.

  Hereinafter, a method for producing the toner of the present invention in the suspension polymerization method will be described.

  First, a low softening point substance, a polar resin, a colorant, a charge control agent, a polymerization initiator, and other additives were added to the polymerizable monomer and dissolved or dispersed uniformly by a homogenizer, an ultrasonic disperser, or the like. The monomer system is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homogenizer, homomixer or the like. At this time, granulation is preferably performed while adjusting the stirring speed and time so that the monomer droplets have a desired developer particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained by the action of the dispersion stabilizer and the sedimentation of the particles is prevented. The polymerization temperature is preferably set to 40 ° C. or higher, generally 50 ° C. to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers and by-products that cause odors when fixing the developer, the latter half of the reaction or at the end of the reaction. A part of the aqueous medium may be distilled off. After completion of the reaction, the produced developer particles are washed, collected by filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 parts by mass to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer system.

  Toner particle size distribution control and particle size control can be done by adjusting the pH of the system during granulation, changing the type and addition amount of a sparingly water-soluble inorganic salt and protective colloid, mechanical equipment conditions, For example, it can be performed by controlling stirring conditions such as the peripheral speed of the rotor, the number of passes, and the shape of the stirring blades, the shape of the container, or the solid content concentration in the aqueous solution.

  Examples of the polymerizable monomer used in the present invention include styrene monomers such as styrene, o- (m-, p-) methylstyrene, m- (p-) ethylenestyrene; methyl (meth) acrylate, Propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; monomers such as butadiene, isoprene, cyclohexane, (meth) acrylonitrile, and acrylamide Preferably used.

  Moreover, as a polar resin added at the time of superposition | polymerization, the copolymer of a styrene (meth) acrylic acid, a maleic acid copolymer, a polyester resin, and an epoxy resin are used preferably.

  Further, as the low softening point substance used in the present invention, paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block compounds thereof are preferably used. It is done.

  As the charge control agent used in the present invention, known ones can be used, but a charge control agent having no polymerization inhibition and no solubilized product in an aqueous system is particularly preferable. Specific examples of negative compounds include salicylic acid, naphthoic acid, dicarboxylic acid, metal compounds of their derivatives, polymer compounds having sulfonic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarene, etc. As the positive system, a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, an imidazole compound, or the like is preferably used. The charge control agent is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Examples of the polymerization initiator used in the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1). -Carbonitrile), azo polymerization initiators such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutylnitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroxy peroxide, A peroxide polymerization initiator such as 2,4-dichlorobenzoyl peroxide or lauroyl peroxide is used.

  The amount of the polymerization initiator to be added varies depending on the target degree of polymerization, but is generally 0.5 to 20% by mass added to the monomer. The kind of the polymerization initiator is slightly different depending on the polymerization method, but may be used alone or mixed with reference to the 10-hour half-life temperature.

  Examples of the dispersant used when using suspension polymerization include inorganic calcium oxides such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, and hydroxide. Examples thereof include magnesium, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic substance, and ferrite. As the organic compound, for example, polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, starch and the like are used dispersed in an aqueous phase.

  These dispersants are preferably used in an amount of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  These commercially available dispersants may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, they can also be obtained by producing the inorganic compound in a dispersion medium under high-speed stirring. . For example, in the case of calcium phosphate, a dispersant preferable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.

  Moreover, you may use together 0.001-0.1 mass part surfactant for refinement | miniaturization of these dispersing agents. Specifically, commercially available nonionic, anionic and cationic surfactants can be used, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, Calcium oleate is preferably used.

  Next, a toner manufacturing method in the kneading and pulverizing method will be described.

  Examples of the binder resin used in the pulverized toner of the present invention include polystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, and styrene-vinyl acetate. Copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid acrylic copolymers, vinyl chloride resins, polyester resins, epoxy resins, phenol resins, polyurethane resins, etc. can be used alone or in combination. -Acrylic, styrene-methacrylic copolymer resin and polyester resin are preferred.

  Further, when the pulverized toner of the present invention is controlled to be positively charged, a modified product of a fatty acid metal salt or the like; 4 such as tributylbenzidyl ammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, etc. Onium salts such as quaternary ammonium salts and their analogs such as phosphonium salts; amine and polyamine compounds; metal salts of higher fatty acids; acetylacetone metal complexes; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide Diorgano tin borate such as dibutyl tin borate, dioctyl tin borate, dicyclohexyl tin borate and the like are added. Moreover, when controlling to negative chargeability, an organometallic complex and a chelate compound are effective, and a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid metal complex can be used. The amount used is 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  A release agent can be added to the pulverized toner of the present invention as necessary. For example, aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, Fischer-Tropsch wax or oxides thereof; waxes mainly composed of aliphatic esters such as carnauba wax and montanic ester wax; And those obtained by deoxidizing some or all of them. In addition, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, and seryl alcohol , Saturated alcohols such as melyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; saturated fatty acid bisamides such as methylene bis stearic acid amide; unsaturated fatty acid amides such as ethylene bisoleic acid amide Aromatic bisamides such as N, N′-distearylisophthalic acid amide; fatty acid metal salts such as zinc stearate; waxes grafted to a hydrocarbon hydrocarbon wax using a vinyl monomer such as styrene; Fatty acids with polyhydric alcohols partial esters of such Henin acid monoglyceride; and methyl ester having a hydroxyl group obtained by and hydrogenated vegetable oils may also be used. The addition amount is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  Next, these binder resins, mold release agents, charge control agents, colorants, etc. are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then a heat kneader such as a heating roll, a kneader or an extruder is used. Dissolve or dissolve the charge control agent and colorant while melting and kneading the resins together. After cooling and solidifying, mechanically pulverize to the desired particle size, and further sharpen the particle size distribution by classification. To do. Alternatively, after cooling and solidification, a finely pulverized product obtained by colliding with a target under a jet stream is spheroidized by heat or mechanical impact force.

  As the colored particles, magnetic particles containing a magnetic material that is relatively hard and therefore has a high scraping power for deposits on the drum surface are more preferable.

  A perovskite inorganic fine powder used in the present invention is externally added to the colored particles thus obtained to obtain a toner.

  Furthermore, in the present invention, the following inorganic powder can be further added to improve developability and durability. Metal oxides such as magnesium, zinc, aluminum, titanium, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, antimony; metal salts such as barium sulfate, calcium carbonate, magnesium carbonate, aluminum carbonate; kaolin, etc. Examples thereof include clay minerals; phosphate compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; and carbon powders such as carbon black and graphite.

  For the same purpose, the following organic particles and composite particles may be added. Resin particles such as polyamide resin particles, silicone resin particles, silicone rubber particles, urethane particles, melamine-formaldehyde particles, acrylic particles; rubbers, waxes, fatty acid compounds, resins, etc. and metals, metal oxides, salts, carbon black, etc. Composite particles composed of inorganic particles; Fluorine resins such as polyfluorinated ethylene and polyvinylidene fluoride; Fluorine compounds such as carbon fluoride; Fatty acid metal salts such as zinc stearate; Fatty acid derivatives such as fatty acids and fatty acid esters; Molybdenum sulfide And amino acids and amino acid derivatives.

[Toner release rate measurement method]
The liberation rate is a ratio obtained by volume% of the inorganic fine powder liberated from the colored particles, and is measured by a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation).

  The particle analyzer performs the measurement according to the principle described on pages 65-68 of the Japan Hardcopy 97 paper collection. Specifically, the apparatus can introduce fine particles such as toner into the plasma one by one and know the element of the luminescent material, the number of particles, and the particle size of the particles from the emission spectrum of the fine particles.

  Among them, the “free rate” is defined as a value obtained by the following equation from the simultaneous emission of light emission of carbon atoms, which are constituent elements of the binder resin, and light emission of constituent atoms of the inorganic fine powder.

Release rate (% by volume) = (Emission volume of only constituent atoms of inorganic fine powder) × 100 / (Emission volume of constituent atoms of inorganic fine powder emitted simultaneously with carbon atoms + Emission volume of only constituent atoms of inorganic fine powder)
Here, “simultaneous light emission” means that light emitted from constituent atoms of the inorganic fine powder emitted within 2.6 msec from light emission of carbon atoms is simultaneous light emission, and thereafter, light emission of constituent atoms of the inorganic fine powder is inorganic fine powder. It is assumed that light is emitted only from the constituent atoms. In the present invention, the luminescence of the constituent atoms of the inorganic fine powder that emits light simultaneously with the carbon atoms is measured from the inorganic fine powder adhered to the surface of the colored particles, and the luminescence of only the constituent atoms of the inorganic fine powder is the inorganic released from the colored particles. The fine powder is being measured.

  As a specific measurement method, helium gas containing 0.1% oxygen was used and the measurement was performed in an environment of 60% humidity at 23 ° C., and the toner sample was left to stand overnight in the same environment to adjust the humidity. Things are used for measurement. In addition, carbon atoms (measurement wavelength 247.860 nm) are measured in channel 1, and constituent atoms of the inorganic fine powder (for example, strontium atoms in the case of strontium titanate: measurement wavelength 407.770 nm) are measured in channel 2, and in one scan. Sampling is performed so that the number of light emission of carbon atoms is 1000 to 1400, and scanning is repeated until the total number of light emission of carbon atoms reaches 10,000 or more, and the light emission number is integrated. At this time, in the distribution in which the number of light emission of the carbon element is taken on the vertical axis and the cube root voltage of the carbon element is taken on the horizontal axis, the distribution has a maximum and further has a valley. Sampling and measurement. Based on this data, the noise cut level of all elements is set to 1.50 V, and the liberation rate is calculated using the above formula.

[Charging]
The corona charger of the present invention includes a corotron type and a scotron type. Among these, the scotron type corona charger is preferable because of excellent uniformity of the charging potential.

  The Scotron corona charger includes a discharge wire, a shield that is a conductive plate that covers the outer periphery of the discharge wire, and a grid that controls the surface potential of the photoconductor in close proximity to the photoconductor.

  As an image forming apparatus for carrying out the image forming method of the present invention, an organic photoconductor digital copying machine using a laser beam (manufactured by Canon Inc .: GP405 remodeling machine) was prepared. The outline of the apparatus includes a corona charger as a charging unit for a photosensitive member, a two-component developing unit adopting a two-component developing method as a developing unit, a transfer roller as a transfer unit, a blade cleaning unit, and a pre-charge exposure. Means. Further, the photosensitive member charger, the cleaning unit, and the photosensitive member are integrated units. The process speed is 210 mm / s. The device was modified as follows.

  First, only in the case where a developing part non-magnetic toner is used, a magnetic carrier (a coated carrier having a volume average particle diameter of 45 μm in which the surface of Cu—Zn ferrite is coated with a silicone resin) and a toner are formed and brought into contact with the photosensitive member. To a two-component developer that adjusts the amount of toner contained in the developer to about 8%, and the developing sleeve is made to be in the same direction as the photosensitive member in the developing portion, and the rotational speed is 250 mm / s. It was. The frequency of development in this case was a constant constant voltage of 4 kHz and a rectangular wave of 1.8 kVpp.

  The potential on the drum was adjusted by changing the DC voltage for charging and development from the dark and light potential on the drum so that the development contrast was 250 V and the back contrast was 150 V. The DC current of the primary charging wire was set to a constant current of −800 μA, and the DC voltage of the grid was evaluated to be a constant voltage of −800V.

<Photoreceptor Production Example 1>
An aluminum cylinder having a diameter of 30 mm × 357.5 mm is used as a support, and a paint composed of the following materials is applied to the support by a dip coating method and thermally cured at 140 ° C. for 30 minutes, and the film thickness is 18 μm. The conductive layer was formed.

Conductive pigment: SnO ₂ coated barium sulfate 10 parts by mass Resistance adjusting pigment: Titanium oxide 2 parts by mass Binder resin: Phenol resin 6 parts by mass Leveling material: Silicone oil 0.001 part by mass Solvents: Methanol, methoxypropanol 0.2 /0.8 15 parts by mass

  Next, a solution obtained by dissolving 3 parts by mass of N-methoxymethylated nylon and 3 parts by mass of copolymer nylon in a mixed solvent of 65 parts by mass of methanol and 30 parts by mass of n-butanol is applied by a dip coating method. An intermediate layer having a thickness of 0.7 μm was formed.

  Next, 4 parts by mass of hydroxygallium phthalocyanine having strong peaks at 7.4 ° and 28.2 ° of black angle 2θ ± 0.2 ° of CuKα characteristic X-ray diffraction, polyvinyl butyral (trade name: ESREC BX-1, Sekisui (Chemical) 2 parts by mass and 80 parts of cyclohexanone were dispersed in a sand mill apparatus using glass beads having a diameter of 1 mm for 4 hours, and then 80 parts by mass of ethyl acetate was added to prepare a dispersion for charge generation layer. This was applied by a dip coating method to form a charge generation layer having a thickness of 0.2 μm.

  Next, 7 parts by mass of a styryl compound represented by the following structural formula (1)

およびポリカーボネート樹脂（ユーピロンＺ８００、三菱エンジニアリングプラスチックス（株）社製）１０質量部をモノクロロベンゼン１０５質量部よびジクロロメタン３５質量部の混合溶媒中に溶解して調整した電荷輸送層用塗料を用いて、前記電荷発生層上に膜厚１０μｍの電荷輸送層を形成し、基体、中間層、導電層、電荷発生層、電荷輸送層からなる４層の感光体を得た。

And a charge transport layer coating material prepared by dissolving 10 parts by mass of polycarbonate resin (Iupilon Z800, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) in a mixed solvent of 105 parts by mass of monochlorobenzene and 35 parts by mass of dichloromethane, A charge transport layer having a thickness of 10 μm was formed on the charge generation layer to obtain a four-layer photoconductor comprising a substrate, an intermediate layer, a conductive layer, a charge generation layer, and a charge transport layer.

  Next, 45 parts by mass of the hole transporting compound (2)

をｎ−プロピルアルコール５５質量部に溶解し、さらにテトラフルオロエチレン微粒子を５質量部添加して、高圧分散機（マイクロフルイタイザー、Ｍｉｃｒｏｆｌｕｉｄｉｃｓ社製）にて分散させた表面保護層用塗料を調製した。この塗料を前記４層感光体上に塗布したのち、弾性変形率とユニバーサル硬さ値が表１になるように、酸素濃度１０ｐｐｍの雰囲気下で電子線を照射した。その後、その雰囲気下で加熱処理を行い、保護層の膜厚３μｍの電子写真感光体αを得た。

Was dissolved in 55 parts by mass of n-propyl alcohol, 5 parts by mass of tetrafluoroethylene fine particles were further added, and a coating material for a surface protective layer was prepared by dispersing with a high-pressure disperser (Microfluidizer, manufactured by Microfluidics). . After this coating material was applied on the four-layer photoconductor, an electron beam was irradiated in an atmosphere having an oxygen concentration of 10 ppm so that the elastic deformation rate and the universal hardness value were as shown in Table 1. Thereafter, heat treatment was performed in the atmosphere to obtain an electrophotographic photosensitive member α having a protective layer thickness of 3 μm.

<Photoreceptor Production Example 2>
As a surface protective layer, 50 parts by mass of the hole transporting compound of the structural formula (2) are dissolved in 55 parts by mass of n-propyl alcohol, 30 parts by mass of tetrafluoroethylene fine particles, and 20 parts by mass of the following structural formula (3). The coating material for the surface protective layer was added and dispersed with a high-pressure disperser (microfluidizer, manufactured by Microfluidics). After this coating material was applied on the four-layer photoconductor, an electron beam was irradiated in an atmosphere having an oxygen concentration of 10 ppm so that the elastic deformation rate and the universal hardness value were as shown in Table 1. Thereafter, heat treatment was performed in the atmosphere to obtain an electrophotographic photoreceptor β having a protective layer thickness of 3 μm.

<Photoreceptor Production Comparative Example 3>
As a surface protective layer, 50 parts by mass of the hole transporting compound of the structural formula (2) is dissolved in 65 parts by mass of n-propyl alcohol, and further 50 parts by mass of tetrafluoroethylene fine particles are added to a high pressure disperser (microfluidizer). (Manufactured by Microfluidics) to prepare a coating material for the surface protective layer. After this coating material was applied on the four-layer photoconductor, an electron beam was irradiated in an atmosphere having an oxygen concentration of 10 ppm so that the elastic deformation rate and the universal hardness value were as shown in Table 1. An electrophotographic photoreceptor γ having a protective layer thickness of 3 μm was obtained.

<Photoconductor Production Comparative Example 4>
As a surface protective layer, 45 parts by mass of the hole transporting compound of the structural formula (2) are dissolved in 55 parts by mass of n-propyl alcohol, and 5 parts by mass of tetrafluoroethylene fine particles are further added, and a high-pressure disperser (microfluidizer). (Manufactured by Microfluidics) to prepare a coating material for the surface protective layer. After this coating material was applied on the four-layer photoconductor, an electron beam was irradiated in an atmosphere having an oxygen concentration of 10 ppm so that the elastic deformation rate and the universal hardness value were as shown in Table 1. Thereafter, heat treatment was performed in the atmosphere to obtain an electrophotographic photoreceptor δ having a protective layer thickness of 3 μm.

  Table 1 below summarizes the photoreceptor characteristics.

<Production Example 1 of Perovskite Type Inorganic Fine Powder>
The hydrous titanium oxide obtained by hydrolyzing the titanyl sulfate aqueous solution was washed with pure water until the electric conductivity of the filtrate reached 2200 μS / cm. NaOH was added to the hydrous titanium oxide slurry, and the sulfate radical adsorbed was washed with SO ₃ until it became 0.24% by mass. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion. NaOH was added to the titania sol dispersion, the pH of the dispersion was 6.2, and the supernatant was washed by decantation with pure water until the electrical conductivity of the supernatant reached 120 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, only the peak of anatase TiO ₂ was shown.

533 g (0.6 mol) of metatitanic acid having a moisture content of 91% obtained as described above was put into a SUS reaction vessel, and nitrogen gas was blown into the vessel and left for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. 183.6 g (0.66 mol) of Sr (OH) ₂ .8H ₂ O (purity 95.5%) was added, and distilled water was further added to add 0.3 mol / liter (SrTiO ₃ equivalent), SrO / TiO _2. The slurry was adjusted to a molar ratio of 1.10. The slurry was heated to a boiling point temperature (101 ° C.) at 28 ° C./1 hour in a nitrogen atmosphere, and reacted at the boiling point for 3 hours. After the reaction, the reaction solution is cooled to 40 ° C., the supernatant is removed under a nitrogen atmosphere, and the operation of adding 2.5 liters of pure water and decanting is repeated twice, followed by filtration with Nutsche. It was. The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours.

  The obtained strontium titanate had an average primary particle size of 80 nm and agglomerates of 600 nm or more in 0.2% by number, and the content of particles having an approximately cubic or rectangular parallelepiped shape was 80% by number. . This strontium titanate is designated as inorganic fine powder a-1.

<Production Examples 2 to 4 and Comparative Production Examples 1 to 3 of Perovskite Type Inorganic Fine Powder>
In perovskite inorganic fine powder production example 1, the reaction temperature of strontium titanate, the rate of temperature rise to the temperature, the reaction time, and the pH of the dispersion were adjusted to produce a perovskite inorganic fine powder having the following characteristics. It is summarized in Table 2 below.

<Production Example 5 of Perovskite Type Inorganic Fine Powder>
100 parts by weight of the inorganic fine powder a-1 is added to a sodium stearate aqueous solution (7 parts by weight of sodium stearate and 100 parts by weight of water), which is a fatty acid metal salt, and the aqueous aluminum sulfate solution is added dropwise with stirring. An inorganic fine powder a-5 was prepared by depositing and adsorbing aluminum stearate on the surface of the powder a-1 to treat the surface. The average particle diameter of a-5 was 90 nm, the number% of 800 nm or more was 0.4%, and the number% of the approximate cube was 85%.

<Colored particle production example 1>
100 parts by mass of styrene acrylic resin (styrene-butyl acrylate copolymer ratio = 78: 22)
Carbon black 10 parts by mass Salicylic acid metal compound 5 parts by mass The above is mixed using a Henschel mixer, melt kneaded with a twin screw extruder kneader, coarsely pulverized with a hammer mill, finely pulverized with a jet mill, and classified. As a result, colored particles X having an average particle size of 6.8 μm were obtained.

<Colored particle production example 2>
100 parts by mass of styrene acrylic resin (styrene-butyl acrylate copolymer ratio = 78: 22)
Magnetic material 10 parts by weight Salicylic acid metal compound 2 parts by weight The above is mixed using a Henschel mixer, melt-kneaded with a twin screw extruder kneader, coarsely ground with a hammer mill, finely ground with a jet mill, and then classified. As a result, colored particles Y having an average particle size of 7.0 μm were obtained.

<Toner Production Examples 1 to 5>
Hydrophobic silica (BET = 130 m ^{2 /} g) 1.5 parts by mass treated with 20 parts by mass of dimethyl silicone oil on 100 parts by mass of silica having a primary particle size of about 7 nm with respect to 100 parts by mass of colored particles X, inorganic fine powder Toners c-1 to 5 were obtained by externally adding 1.5 parts by mass of a-1 to 5 with a Henschel mixer FM10B.

<Toner Production Example 6>
1.2 parts by mass of hydrophobic silica (BET = 130 m ^{2 /} g) surface-treated with 20 parts by mass of dimethyl silicone oil on 100 parts by mass of silica having a primary particle size of about 7 nm with respect to 100 parts by mass of colored particles Y, and inorganic fine powder Toner c-6 was obtained by externally adding 1.5 parts by weight of a-1 using a Henschel mixer FM10B.

<Toner Production Example 7>
Toner c-7 was produced in the same manner as c-1, except that the external addition time of toner c-1 was shortened to 1/3.

<Toner Comparative Production Examples 1-3>
Hydrophobic silica (BET = 130 m ^{2 /} g) 1.2 parts surface-treated with 20 parts by mass of dimethyl silicone oil to 100 parts by mass of silica having a primary particle size of about 7 nm with respect to 100 parts by mass of colored particles X, inorganic fine powder b Toners d-1 to 3 were obtained by externally adding 1.5 parts by weight of -1 to 3 to a Henschel mixer FM10B.

<Toner Comparative Production Example 4>
Toner d-4 was produced in the same manner as d-1, except that the external addition time of toner d-1 was shortened to 1/3.

  Table 3 below summarizes the toner characteristics.

<Examples 1-4, Reference Examples, Examples 5-7 , Comparative Examples 1-6>
Evaluation was performed using the image forming apparatus, the drum, and the toner according to the following evaluation method.

Evaluation 1)
A 30% / 80% environment was used, and an image ratio of 2% and 100,000 A4 landscape paper were endured, and a halftone image was produced. White streaks were evaluated according to the following evaluation items.
A: There are no white stripes.
B: Slight white streaks are present but not noticeable.
C: There is a clear white streak and it stands out.

Evaluation 2)
In a state where the development and the back contrast time control are adjusted by the developing bias so that the toner is developed on the photosensitive member in a 32.5 ° C./85% environment for 1 second every 5 seconds, and the transfer is released. A corona charge was applied to perform idling for 2 hours. In order to investigate the wire contamination of the corona charger due to toner scattering, analog halftone and halftone images were drawn and evaluated according to the following evaluation items.
A: There is no defective charging and the image is good.
B: Although the halftone image is good, charging failure is confirmed in the analog halftone image.
C: Charging failure is confirmed in halftone and analog halftone images.

Evaluation 3)
Durability of 100,000 sheets of image ratio 2% and A4 landscape paper was performed in an environment of 15 ° C./10%, and the state of drum scratches after durability was evaluated according to the following evaluation items.
A: Minor or no scratch.
B: Although there is a scratch of 3 μm or less, the CT layer is not reached, and the image is not affected.
C: The scratch is deep and reaches the CT layer, affecting the output image.

Evaluation 4)
Endured by 100,000 sheets of 2% image ratio and 100,000 A4 horizontal paper under 30 ° C / 80% environment, observed the entire blade longitudinal direction using a 500x optical microscope, and evaluated the state of the blade according to the following evaluation items Went.
A: No chipping of the blade is observed.

B: The size of the blade chip is less than 5 μm.
C: The blade is missing or is 5 μm or more, and the toner slips through and the image is defective.

  Table 4 below shows the toner and drum evaluation results used in Examples and Comparative Examples.

  From the above results, in evaluation 1, when the average particle size of the inorganic fine powder externally added to the toner was 170 nm or less, white streaks were effectively suppressed. This is considered to be because the adhered substance on the photoconductor can be uniformly polished.

  In Evaluation 2, charging failure occurred when the average particle size of the external additive was less than 30 nm. Further, when the liberation rate of the external additive was larger than 30%, charging failure occurred. This is considered to be because the external additive having a small particle size and a high liberation rate easily scatters and contaminates the charger.

1 is a diagram illustrating an example of a specific image forming apparatus of the present invention. It is a figure which shows an example of a film | membrane characteristic output chart. It is a figure which shows an example of the film | membrane characteristic measurement of a photoreceptor protective layer. It is a figure based on an example of the electron micrograph (50,000 times) of inorganic fine powder. It is the schematic of the long side and short side in the particle size measurement of an inorganic fine powder.

Explanation of symbols

1: Photosensitive drum 2: Frame 3: Fixing device 4: Cleaning elastic blade 5: Transfer material 6: Corona charger 7: Developer 8: Transfer charging roller L: Laser light L

Claims (6)

A step of charging a photoconductor having a photosensitive layer and a protective layer on a support, which is an image carrier, by corona discharge, an electrostatic latent image forming step of forming an electrostatic latent image on the charged photoconductor, and a toner carrying A development process for visualizing the toner carried on the body by transferring it to the electrostatic latent image, and transferring the toner image formed on the image carrier to a transfer material with or without an intermediate transfer body. An image forming method including at least a transfer step and a cleaning step of removing transfer residual toner remaining on the photoconductor after the transfer step from the photoconductor.
The surface of the protective layer of the photoconductor is subjected to a hardness test using a Vickers square pyramid diamond indenter in an environment of 25 ° C. and a humidity of 50%, and the HU (Universal Hardness Value) when pressed at a maximum load of 6 mN is 150 or more. 240 or less (N / mm ² ), and the elastic deformation rate is 44% or more and 65% or less,
The toner has colored particles containing at least a binder resin and a colorant;
Further, at least the toner has an inorganic fine powder of perovskite crystal in which the average particle size of primary particles is 30 nm or more and 120 nm or less and the number of particles having an aggregate particle size of 600 nm or more is 0.5 % by number or less. On the other hand, 0.2 mass% or more and 4 mass% or less are externally added,
The inorganic fine powder contains 65% by number or more whose primary particle shape is approximately cubic or rectangular parallelepiped,
The liberation rate of the inorganic fine powder in the toner is 13 to 32% by volume,
The inorganic fine powder is strontium titanate or barium titanate,
An image forming method, wherein a transfer residual toner remaining on a photoconductor after the transfer step is removed from the photoconductor by a cleaning blade in which the inorganic fine powder stays. 2. The image forming method according to claim 1, wherein the inorganic fine powder is subjected to a surface treatment. The image forming method according to claim 2, characterized in that said toner is a magnetic toner containing a magnetic material. The image forming method according to any one of claims 1 to 3, characterized in that the protective layer of the photoreceptor is a protective layer which is formed by a curable resin containing a charge transport material. The protective layer of the photoreceptor is formed by irradiation with radiation, and the protective layer formed by irradiation with radiation is a layer cured by polymerizing or crosslinking a compound having a chain polymerizable functional group the image forming method according to any one of claims 1 to 4 is. Charging means by corona discharge to the photosensitive body, the image forming method according to any one of claims 1 to 5, characterized in that a scorotron type corona charger having a discharge wire and grid in the shield.

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