JP5693128B2 - Developing device and electrophotographic apparatus. - Google Patents

Description

The present invention relates to a developing device and an electrophotographic apparatus.

  In the formation of electrophotographic images, in response to the recent demand for higher image quality, a bias is applied to the developing blade that regulates the amount of toner on the developing roller to efficiently frictionally charge the toner and reduce the toner coating amount. A developing device that stabilizes is proposed in Japanese Patent Application Laid-Open No. H10-228707.

  However, when an image is formed by applying a bias to the developing blade, depending on the developing roller to be used, image defects such as a decrease in current value due to energization of the developing roller in continuous image formation and density unevenness due to variation in volume resistance may occur. There is a case.

  As a technique for reducing the hardness of the elastic layer of the developing roller, Patent Document 2 has conventionally proposed a method of blending a large amount of softener. Further, as a countermeasure against bleeding of a softener, Patent Document 3 proposes a low molecular weight oil added with a gelling agent. As a proposal regarding the decrease in the current value of the developing roller that occurs during continuous image formation, Patent Document 4 discloses a method using two types of carbon black having different characteristics, or Patent Document 5 discloses that hydrophobic conductive fine particles and hydrophilicity are used for the surface layer. A method of mixing the conductive fine particles has been proposed.

JP 2000-112212 A JP 2007-240742 A JP 2008-249860 A Japanese Patent Laid-Open No. 10-254215 JP 2001-100490 A

  In the case of reducing the hardness of an elastic layer using a softening agent, it is considered that the softening agent exerts a reduction in hardness by entering and moving between crosslinked rubber polymers. When a large amount of a softening agent is added, the softening agent moves and diffuses in the elastic layer, promotes the movement of other conductive agents, and may cause a decrease in current value due to energization. It has been pointed out that this phenomenon causes various adverse effects in electrophotographic image formation, such as a decrease in printing density and density gradation. Further, there is a higher possibility that harmful effects on the concentration will occur under high temperature and high humidity. Therefore, there is a demand for a developing roller that suppresses a decrease in current value even when the developing roller is used for a long period of time under high temperature and high humidity. Further, when the softening agent moves, a so-called bleeding phenomenon that oozes out on the surface of the developing roller is caused. Due to this bleed, the softening agent may be transferred to the photoreceptor and contaminated, which may cause image defects such as white spots.

An object of the present invention is to provide a developing device and an image forming device that contribute to stable formation of a high-quality electrophotographic image by suppressing a decrease in the current value of the developing roller and bleed in a developing device that applies a bias to a developing blade. There is to do.

The present inventors have provided a developing device using a developing roller that achieves low hardness and suppresses a decrease in current value and bleeding in a developing roller used in a developing device that applies a bias to a developing blade. We conducted an intensive study. As a result, it has been found that a developing device and an image forming apparatus that can achieve the above object can be obtained.

That is, the present invention provides a developing container that contains toner, a developing roller that is rotatably supported by the opening of the developing container, a developing blade that regulates the amount of toner carried by the developing roller, and the developing A developing device comprising a means for applying a bias to the blade, and developing a latent image on the photoreceptor facing the developing roller with toner,
The developing roller has a conductive core, an elastic layer formed on the outer periphery of the conductive core, and a coating layer formed on the outer periphery of the elastic layer,
The elastic layer is
A crosslinked rubber having a polyalkylene structure in the main chain ;
A saturated hydrocarbon compound having a number average molecular weight of 300 to 30,000 ,
A saturated aliphatic hydroxycarboxylic acid having 12 to 20 carbon atoms ;
Carbon black as a conductive agent,
The saturated hydrocarbon compound is contained in the elastic layer in an amount of 15% by mass to 50% by mass with respect to the total mass of the elastic layer,
Saturated aliphatic hydroxycarboxylic acid is a developing apparatus is characterized in that it is contained in the elastic layer below 5.0 part by mass or more 0.1 part by mass with respect to the saturated hydrocarbon compound 100 parts by weight .

  Furthermore, the present invention comprises a developing container for containing toner, a developing roller, a developing blade for regulating the amount of toner carried by the developing roller, and means for applying a bias to the developing blade, An electrophotographic apparatus having a developing device that develops a latent image on a photoconductor facing a developing roller, wherein the developing device is the developing device described above.

As described above, according to the present invention, the developing roller used in the developing device that applies a bias to the developing blade can achieve low hardness, and can effectively suppress bleed and decrease in current value. . Therefore, it is possible to provide a developing device and an image forming apparatus having a bias applying means to the developing blade using a developing roller that has this excellent bleed suppression and can suppress a decrease in current value.

The reason for this is not clear, but is presumed as follows. In the present invention, the saturated hydrocarbon compound and the saturated aliphatic hydroxycarboxylic acid are contained in the crosslinked rubber having a polyalkylene structure in the main chain in the elastic layer. Saturated hydrocarbon compounds have a high affinity with the polyalkylene structure and contribute to lowering the hardness of the elastic layer, and saturated aliphatic hydroxycarboxylic acids have a function of suppressing migration and diffusion of saturated hydrocarbon compounds in the elastic layer. . For this reason, the saturated aliphatic hydroxycarboxylic acid captures the saturated hydrocarbon compound and suppresses migration and diffusion of the saturated hydrocarbon compound, thereby suppressing the movement of the conductive agent in the elastic layer. Is considered to be suppressed. Furthermore, since the number average molecular weight of the saturated hydrocarbon compound is 300 or more and 30000 or less, it is possible to suppress a decrease in the current value of the developing roller even in a developing device that receives a strong electric field that applies a bias to the developing blade. A developing device excellent in formation can be obtained.

It is sectional drawing which shows the outline of the developing roller used for the image development apparatus of this invention. It is the figure which showed the measuring method of the electric current value of the developing roller used for this invention with the schematic diagram. 1 is a cross-sectional view illustrating a schematic configuration of an electrophotographic apparatus of the present invention. It is sectional drawing which shows schematic structure of an electrophotographic process cartridge.

  As shown in FIG. 1, the developing roller used in the developing device of the present invention has an elastic layer 2 on a conductive core 1 and a coating layer 3 on the outer periphery thereof. The elastic layer is made of an elastic body and means a solid having a property of returning to its original shape when the stress is removed, although it is deformed by an external stress.

  There are several factors in the phenomenon that the current value of the developing roller decreases due to the continuous image formation. One of them is the movement of the conductive agent in the elastic layer. Even in the crosslinked rubber, it is considered that the electric resistance received from the outside moves the conductive agent in a fine range and increases the volume resistance. At this time, fine and highly cohesive particles such as a conductive agent move in the direction of agglomeration between neighboring particles, so that a part where the interparticle distance is partially separated occurs. As a result, it is considered that the current value decreases due to defects in the conductive part formed on the mesh. Therefore, when used in a developing device that applies a bias to the developing blade in the present invention, the developing bias receives a strong electric field, and a material design that further suppresses the movement of the conductive agent is required. Also, if the developing blade bias is reduced to weaken the electric field and suppress the movement of the conductive agent, the effect of the developing blade bias is diminished, and it is difficult to ensure uniform charging of the toner and a high-definition image cannot be obtained. There is.

  By applying a bias to the developing blade, evenly charged toner can be charged even to a toner having a small particle size for high-definition image, and a stable toner layer can be formed on the developing roller. There is an advantage that stabilization and resolution are improved.

  Examples of the crosslinked rubber containing a polyalkylene structure in the main chain used in the present invention include the following. Ethylene-propylene rubber, ethylene-propylene-diene rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber and the like.

  Among these crosslinked rubbers, ethylene-propylene-diene rubber, butadiene rubber, and isoprene rubber are preferable because of their affinity with the saturated hydrocarbon compound. Among them, ethylene-propylene-diene rubber is particularly preferable because the main chain is a saturated hydrocarbon and is excellent in compatibility with the saturated hydrocarbon compound.

  The ethylene-propylene-diene rubber used in the present invention can be either oil-extended or non-oil-extended for the purpose of improving processability. In the case of oil-extended ethylene-propylene-diene rubber, the mass of ethylene-propylene-diene rubber refers to the mass of only the rubber component obtained by removing the saturated hydrocarbon compound from the oil-extended ethylene-propylene-diene rubber. The mass of the saturated hydrocarbon compound contained in the oil-extended ethylene-propylene-diene rubber is included in the saturated hydrocarbon compound in the present invention. Further, two or more kinds of the ethylene-propylene-diene rubbers can be mixed and used according to the purpose. When the oil-extended ethylene-propylene-diene rubber is contained in the mixed ethylene-propylene-diene rubber, conversion of the contained mass is performed separately for each component. That is, the mass of the ethylene-propylene-diene rubber and the mass of the saturated hydrocarbon compound in the oil-extended ethylene-propylene-diene rubber are included in the mass of the ethylene-propylene-diene rubber and the saturated hydrocarbon compound in the elastic layer, respectively. . The iodine value of the ethylene-propylene-diene rubber in the present invention is suitably from 10 to 40 in view of dispersibility of the saturated hydrocarbon compound and elasticity of the elastic layer. The ethylene-propylene-diene rubber used in the present invention can be used as long as it is practically used, but in particular, a polymer in which ethylidene norbornene, hexadiene or octadiene is used as the third component diene monomer is used. Among these, ethylene-propylene-diene rubber containing ethylidene norbornene as the third component is preferably used in that the crosslinking speed is high and the physical properties are balanced. Two or more ethylene-propylene-diene rubbers having different iodine values may be mixed and used.

  Specific examples of the ethylene-propylene-diene rubber that are practically used industrially include the following. Esplene 201, 301, 305, 400, 501A, 502, 505, 505A, 512F, 514F, 522, 524, 532, 552, 553, 567, 582F, 586, 600F, 601F, 606F, 671F, 6735, 5214 , 5754, 6506S, 6182F (trade name, manufactured by Sumitomo Chemical Co., Ltd.), JSR EP912P, EP01P, EP02P, EP941P, EP961SP, EP07P, EP57P, EP181SP, EP11, EP43, EP93, EP24, EP27, EP21, EP132, EP22 EP25, EP33, EP35, EP37C / F, EP65, EP51, EP57C / F, EP75F, EP86, EP96, EP98, EP103AF, EP106EF, EP107F, EP801E, EP001DE (trade names, manufactured by JSR Corporation) NORDEL 1040, 1070, 1145, 1320, 1440, 1470, 1660, 2522, 2722 / P, 2744 / P, 2760 / P (trade names, manufactured by DuPont), Epsyn 40-A, 70-A, 55, 2308, 2506, 4506, 4906, 5206, 5508, 5805, 7506, E801, N557, N597, N997, P557, P558, P597, MDE239, MDE248 (trade name, copolymer rubber)・ And Chemical Corporation), POLYSAR 227,306,345,585,487XP, 865,965,5465,5672X, 5875,6463 (trade name, manufactured by Policer Rubber Corporation) Etc..

  The saturated hydrocarbon compound in the present invention means an organic compound in which no double bond is contained in the molecule and carbon-carbon atoms are connected by a single bond. The saturated hydrocarbon compound may be any of a non-cyclic saturated hydrocarbon (alkane) including both a straight chain and a branched chain, and a non-cyclic saturated hydrocarbon. It is a hydrocarbon.

  The saturated hydrocarbon compound used in the present invention has a number average molecular weight of 300 to 30,000, and the content in the elastic layer is 15% by mass to 50% by mass with respect to the total mass of the elastic layer. When the number average molecular weight is less than 300, it is easy to move and diffuse in the elastic layer, and the current value of the developing roller causes aggregation of the conductive agent due to generation of bleed or movement of the conductive agent due to the movement and diffusion of the saturated hydrocarbon compound. Is likely to occur. From the above, if the number average molecular weight of the saturated hydrocarbon compound is 300 or more, a decrease in the current value of the developing roller can be suppressed. Furthermore, if the number average molecular weight of the saturated hydrocarbon compound is 1000 or more and 30000 or less, the effect is higher. When the number average molecular weight is larger than 30000, the saturated hydrocarbon compound is difficult to enter into the crosslinked rubber, and the hardness of the elastic layer is not reduced, resulting in a high-hardness developing roller and stable contact with the photoreceptor. It becomes difficult to secure the width.

  In addition, when the content of the saturated hydrocarbon compound in the elastic layer is less than 15% by mass, the elastic layer is insufficiently reduced in hardness, and the developing roller has a high hardness, so that it is difficult to ensure a stable contact width with the photoreceptor. If the amount is more than 50% by mass, the occurrence of bleeding may occur.

  The total carbon number of the saturated aliphatic hydroxycarboxylic acid used in the present invention is 12 or more and 20 or less. When the total number of carbon atoms of the saturated aliphatic hydroxycarboxylic acid is less than 12, the effect of suppressing the mobility of the saturated hydrocarbon compound is weak, and the current value of the developing roller tends to decrease. Further, when the total number of carbon atoms is more than 20, the dispersibility in the elastic roller is lowered, and there is a concern that unevenness in current value and unevenness in hardness may occur, resulting in image defects. Among them, when the total number of carbon atoms of the saturated aliphatic hydroxycarboxylic acid is 18, it is possible to suppress the migration and diffusion of the saturated hydrocarbon compound and to have a good balance of dispersibility and to stably suppress the migration of the saturated hydrocarbon compound. This is possible and more suitable. The addition amount of the saturated aliphatic hydroxycarboxylic acid in the present invention is 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the saturated hydrocarbon compound. If the amount is less than 0.1 parts by mass, the mobility of the saturated hydrocarbon compound is not sufficiently suppressed, resulting in a decrease in current value. If the amount is more than 5 parts by mass, the dispersion of saturated hydroxycarboxylic acid becomes poor, and image defects such as density unevenness are caused. May occur. Examples of the saturated aliphatic hydroxycarboxylic acid include the following. Hydroxy lauric acid, hydroxy myristic acid, hydroxy pentadecylic acid, hydroxy palmitic acid, hydroxy margaric acid, hydroxy stearic acid, hydroxy nonadecanoic acid, hydroxy arachidic acid. The hydroxy group has one or more hydroxy groups in one molecule, and the binding site is not limited. These can generally be obtained by hydrolyzing and purifying vegetable oil, wax and the like by conventional methods. These saturated aliphatic hydroxycarboxylic acids can be used alone or in admixture of two or more.

  Furthermore, various additives such as a conductive agent, a filler, an extender, a cross-linking agent, a cross-linking aid, an antioxidant, an anti-aging agent, or a processing aid can be used for the elastic layer as necessary. . As the conductive agent, carbon black can be suitably used in terms of performance, quality, and cost.

  When kneading the saturated hydrocarbon compound and saturated aliphatic hydroxycarboxylic acid, even if kneaded in the rubber simultaneously with other additives, the saturated hydrocarbon compound and saturated aliphatic hydroxycarboxylic acid before kneading in the rubber Alternatively, a kneaded product may be prepared and then kneaded. When the saturated hydrocarbon compound and the saturated aliphatic hydroxycarboxylic acid are mixed before kneading into rubber, it is more effective for suppressing bleeding and suppressing decrease in current value.

  The method for molding the elastic layer in the present invention can be produced by a conventionally known molding method such as an extrusion molding method or an injection molding method. The layer structure is not limited as long as it has the characteristics described in the present invention, and can be a structure of one layer or two or more layers. The thickness of the elastic layer is not particularly limited as long as it has the characteristics described in the present invention, but is preferably 1 mm or more and 5 mm or less. If it is less than 1 mm, it does not function as an elastic layer, and it is easy to promote the deterioration of the toner. If it is thicker than 5 mm, the molding processability becomes unstable, the shape becomes poor, and image defects such as step unevenness may occur.

  In the present invention, a coating layer is further provided on the outer periphery of the elastic layer. In the case of forming the coating layer, the outer periphery of the elastic layer is subjected to surface modification methods such as corona treatment, frame treatment, and excimer UV treatment in order to improve adhesion so that peeling between the elastic layer and the coating layer does not occur. It may be modified.

  In the present invention, the number average molecular weight of each sample is measured by gel permeation chromatography. The measurement method of the gel permeation chromatography method is as follows. That is, the column is stabilized in a heat chamber at 40 ° C., THF (tetrahydrofuran) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min, and about 100 μl of the THF sample solution is injected and measured. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. An RI (refractive index) detector is used as the detector.

  The following are mentioned as a kind of coating layer in this invention.

  Examples of the organic coating layer include coating layers formed of the following resins. Polyamide resin; Fluorine resin; Styrenic resin; Vinyl resin; Polycarbonate resin; Acrylic resin; Polyethylene, polypropylene, Ethylene vinyl acetate copolymer polyolefin resin, etc .; Epoxy resin, polyester resin, alkyd resin, Thermosetting resins such as phenolic resin, melamine resin, polyurethane resin, urea resin, silicone resin, polyimide resin.

  Examples of the inorganic coating layer include a silica film and a carbon film. The silica film has O—Si—O as the main skeleton, the proportion of Si and O in all elements is 60% or more, and Si includes SiOx in which at least one of H, O, and C is bonded to Si. It is done. Examples of the carbon film include diamond-like carbon (DLC) which is a carbon thin film having high hardness, electrical insulation, and infrared transmission. The structure of the early DLC is an amorphous structure having C as the main skeleton and containing some H, and both diamond bonds (SP3 bonds) and graphite bonds (SP2 bonds) are mixed.

  The thickness of these coating layers is appropriately selected depending on the type of coating layer to be formed and the forming method.

  In the case of an organic coating layer, the thickness is 3 μm or more and 100 μm or less. If the thickness is less than 3 μm, the bleedness is not sufficiently suppressed, and if it is thicker than 100 μm, it may cause uneven volume resistance of the developing roller.

  The thickness of the inorganic coating layer is preferably 0.01 μm or more and 3 μm or less. If the thickness is less than 0.01 μm, it is difficult to coat the elastic layer, and the elastic layer is likely to be scraped or worn. If the thickness is larger than 3 μm, the coating layer may be cracked.

  Examples of the method for forming the coating layer in the present invention include a method of forming by a coating method such as dip coating, spray coating, and roll coating. Alternatively, a known coating layer forming method such as a method such as multilayer extrusion molding or tube coating or a method formed by a plasma CVD method may be used.

  Further, the configuration of the coating layer is not limited as long as it has the characteristics described in the present invention, and the configuration of one layer or two or more layers can be adopted.

  As the conductive core of the developing roller used in the present invention, those conventionally used for this type of developing roller can be used, and the material has sufficient strength and conductivity. If it does, it will not be limited in particular.

  As the toner used in the developing method in the present invention, known toners conventionally used in this field such as pulverized toner and polymerized toner can be used.

  A method for measuring the current value of the developing roller is shown in FIG. 2 as a schematic diagram. The current value of the developing roller was measured by the following method in an environment of a temperature of 40 ° C. and a relative humidity of 95% RH. That is, the developing roller is brought into contact with the SUS drum 6 having a diameter of 40 mm, and a load 4 of 500 g is applied to both ends exposed portions of the conductive core for a total load of 1 kg. In this state, the roller is rotated at 45 rpm, the internal resistance 7 of 10 kΩ is arranged on the ground side, and the current value when 100 V is applied for 2 seconds from the DC power source 8 is 21 points every 0.1 second by the multimeter 5. taking measurement. Then, the average value of the current values during one round of the developing roller is defined as the current value of the developing roller. The current value of the developing roller is preferably 10 μA or more and 3000 μA or less. If the current value of the developing roller is less than 10 μA, the density of the solid image may be insufficient, and if the current value of the developing roller is 3000 μA or more, current leakage may occur and the image may be defective if the photoreceptor is defective. There is a case.

The developing device according to the present invention includes the developing roller described above. The developing device includes a developing container that contains toner, a developing roller that is rotatably supported by the opening of the developing container, a developing blade that regulates the amount of toner carried by the developing roller, and a bias applied to the developing blade. It can be set as the structure which has a means to apply.
<Electrophotographic device>
Next, an electrophotographic process cartridge and an electrophotographic apparatus provided with the developing device according to the present invention will be described. 3 to 4 are cross-sectional views showing the schematic configuration of the electrophotographic process cartridge and the electrophotographic apparatus provided with the developing device according to the present invention.

  The photosensitive member 9 rotates in the direction of the arrow, is uniformly charged by the charging roller 16, and an electrostatic latent image is formed on the photosensitive member by laser light 15 that is an exposure unit that writes an electrostatic latent image on the photosensitive member 9. The The electrostatic latent image is visualized as a toner image by being provided with toner 12 by a developing container 14 disposed in contact with the photoreceptor 9. In the developing container 14, the toner is applied to the developing roller 10 and the developing roller, and at the same time, the toner applying member 11 that scrapes the toner remaining on the developing roller without being used for image formation, and the toner on the developing roller 10 in a thin film form. And a developing blade 13 that is frictionally charged. Further, a developing blade bias power source 23 is provided as a bias applying unit that applies a bias of a constant voltage controlled to the developing blade 13 with high accuracy.

  Further, a developing roller bias power source 24 is provided as bias applying means for applying a constant voltage bias controlled to the developing roller 10 with high accuracy. The developing blade bias applied to the developing blade may be on the same polarity side as the toner with respect to the developing bias. Development is so-called reversal development in which a toner image is formed on the exposed portion. The visualized toner image on the photoconductor 9 is transferred to a paper 29 as a recording medium by a transfer roller 21 as a transfer member. The paper 29 to which the toner image has been transferred is subjected to fixing processing by the fixing device 19 and is discharged out of the device, thus completing the printing operation.

  On the other hand, the toner remaining on the photoconductor 9 without being transferred is scraped off by a cleaning blade 18 which is a cleaning member for cleaning the surface of the photoconductor 9 and stored in a waste toner container 17 and cleaned. Repeats the above action.

  The unit consisting of a developing container 14 containing non-magnetic toner as a one-component toner and a developing roller 10 positioned in an opening extending in the longitudinal direction in the developing container and disposed opposite to the photosensitive member 9 is a main unit of the developing device. The electrostatic latent image on the photoconductor 9 is developed and visualized.

  An example of an electrophotographic process cartridge is shown in FIG. The cartridge main body has at least a developing roller 10 and a developing container 14 for containing toner 12, and a toner applying member 11, a photoreceptor 9, and a charging roller 16 may be incorporated. These members are integrally held, and are provided so that they can be detachably attached to the electrophotographic apparatus main body.

Hereinafter, the present invention will be described in more detail with reference to examples. Moreover, when there was no description in raw materials in particular, the commercially available high purity goods were used.
[Example 1]
[Production of elastic layer of developing roller]
The material used as each component which comprises an elastic layer is described below with a compounding ratio (displayed by a mass part).

  It mix | blended so that the total mass might be set to 5 kg with said mixing | blending ratio, and knead | mixed with 6 liter kneader TD6-15MDX (brand name, the product made by Toshin). Thereafter, 1 part by mass of sulfur as a crosslinking agent and 1 part by mass of mercaptobenzothiazole (MBT) as a crosslinking aid were mixed with an open roll to obtain an unvulcanized rubber composition as an elastic body. The content of the saturated hydrocarbon compound in the obtained elastic layer was 30% by mass, and 12-hydroxycarboxylic acid was 1.0 part by mass with respect to the saturated hydrocarbon compound.

  The obtained unvulcanized rubber composition was extruded into a tube shape by a vent type rubber extruder (φ50 mm vent extruder L / D = 16 manufactured by EM Giken Co., Ltd.), and pressurized steam using a vulcanized can at 160 ° C. for 30 minutes. The primary vulcanization was performed. As a result, a rubber tube having an outer diameter of 14 mm, an inner diameter of 5.5 mm, and a length of 250 mm was obtained.

A cylindrical conductive core (made of sulfur composite free-cutting steel, nickel plated on the surface) having a diameter of 6 mm and a length of 252 mm was used as the shaft core of the developing roller. The rubber tube mentioned above is press-fitted into 232 mm of the axial center part of the cylindrical surface of the conductive core applied with Chemlock 459X (trade name, manufactured by Rhode) as a primer, and heated at 160 ° C. for 2 hours in a hot air furnace. Secondary vulcanization and adhesion treatment were performed. Cut both ends of the rubber of the vulcanized roller to make the length of the rubber part 232 mm, and then use a GC80 grindstone for the rubber part to rotate the grinder LEO-600-F4L-BME (trade name, Mizuguchi Seisakusho) To obtain an elastic layer having a linear elastic layer having a diameter of 12 mm.
[Preparation of coating layer for developing roller]
As a material for the covering layer, Nippon Run 5033 (trade name, manufactured by Nippon Polyurethane Co., Ltd.) was used, and isocyanate coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) was combined as a curing agent to make 100 parts by mass. The ratio was such that the molar ratio of [NCO] / [OH] was 1.2. Further, 30 parts by mass of carbon black MA100 (trade name, manufactured by Mitsubishi Chemical Corporation) was added. An organic solvent was added to the raw material mixture, and the solid content was adjusted in the range of 20% to 30% so that the film thickness of the coating layer was 20 μm. 5 parts by mass of urethane resin particles CFB-101-40 (trade name, manufactured by Dainippon Ink & Chemicals, Inc.) having an average particle diameter of 16 μm are added to the raw material mixed solution to which the organic solvent is added, and the mixture is uniformly dispersed and mixed. The raw material liquid for the layer was used. The obtained elastic roller was dipped and coated in this resin raw material liquid, then pulled up, dried, and heat-treated at 160 ° C. for 20 minutes to provide a coating layer of about 20 μm on the outer periphery of the elastic layer. A developing roller was produced.
[Change in current value of developing roller due to energization]
The obtained developing roller was energized for 10 minutes at an applied voltage of 50 v using the evaluation system shown in FIG. 2 in an environment of a temperature of 40 ° C. and a relative humidity of 95% RH. The comparison (current value after test / current value before test) was evaluated according to the following criteria.
A: 50% or more B: 10% or more and less than 50% C: 5% or more and less than 10% D: less than 5% [developing roller bleed]
The obtained developing roller was left in a constant temperature and humidity chamber having a temperature of 40 ° C. and a humidity of 95% for 1 week. Thereafter, it was taken out and incorporated into an electrophotographic process cartridge using a phosphor bronze blade having a thickness of 100 μm as a developing blade of a color laser printer LBP5400 (trade name, manufactured by Canon Inc.). The electrophotographic process cartridge was attached to an LBP 5400 main body (hereinafter referred to as LBP 5400 remodeling machine) modified so that a developing blade bias could be applied to the phosphor bronze blade. Then, under a temperature of 23 ° C. and a relative humidity of 50%, a blade bias was applied so as to be −200 V with respect to the developing bias, and 10 halftone images with a printing rate of 50% were output. The image was evaluated for the presence or absence of white image defects in the period of the developing roller according to the following criteria.

  A: There is no white image defect due to the influence of bleeding on the halftone image.

  B: A slight white image defect is seen in the first output image, but it is not seen after several sheets are passed.

  C: There is a slight white image defect even after 10 sheets are output.

D: There is a white image defect even after 10 sheets are output.
[Density unevenness]
The obtained developing roller was left in a constant temperature and humidity chamber at a temperature of 40 ° C. and a relative humidity of 95% for 1 week and then taken out. The developing roller used was a LBP5400 (product name: Canon Inc.) using a phosphor bronze blade having a thickness of 100 μm. It was attached to an electrophotographic process cartridge. The electrophotographic process cartridge was incorporated into the LBP5400 modified machine main body. After that, the blade bias was applied to -200v with respect to the developing bias in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and a halftone image having a printing rate of 50% density was color copied with a modified LBP5400. Output to plain paper for machine use (80 g / m ² , manufactured by Canon Sales). Regarding the evaluation of the output result, the presence or absence of density unevenness was confirmed visually to determine the practicality.

  A: Density unevenness is not seen.

  B: Density unevenness is very slight and hardly seen.

  C: Density unevenness is observed in a range of 20% or less of the image area.

D: Density unevenness is observed in a range wider than 20% of the image area.
[Example 2]
The saturated hydrocarbon compound of Example 1 was replaced with Lucante HC-2000 by Moresco P-70 (trade name, manufactured by Matsumura Oil Research Co., Ltd., Mn = 300), the addition amount was 23.5 parts by mass, and 12-hydroxystearic acid Was added at 0.0235 parts by mass. The content of the saturated hydrocarbon compound in the obtained elastic layer was 15% by mass, and 12-hydroxycarboxylic acid was 0.1 part by mass relative to the saturated hydrocarbon compound. Other than this, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 3]
The addition amount of Moresco P-70 in Example 2 was changed to 133 parts by mass, and the addition amount of 12-hydroxystearic acid was 0.133 parts by mass. The content of the saturated hydrocarbon compound in the obtained elastic layer was 50% by mass, and 12-hydroxycarboxylic acid was 0.1 part by mass with respect to the saturated hydrocarbon compound. Other than this, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 4]
The amount of 12-hydroxystearic acid added in Example 2 was changed to 1.2 parts by mass, and 12-hydroxycarboxylic acid was blended so as to be 5.0 parts by mass with respect to the saturated hydrocarbon compound. Developed a developing roller by the same method as in Example 1 and evaluated.
[Example 5]
The Lucant HC-2000 of Example 1 was replaced with Moresco P-70 (trade name, manufactured by Matsumura Oil Research Institute), the addition amount was 140 parts by mass, and the addition amount of 12-hydroxystearic acid was 7.0 parts by mass. . The content of the saturated hydrocarbon compound in the obtained elastic layer was 50% by mass, and 12-hydroxycarboxylic acid was 5.0 parts by mass with respect to the saturated hydrocarbon compound. Other than that, a developing roller was produced in the same manner as in Example 1 and evaluated.
[Example 6]
Claprene LIR-50 (trade name, manufactured by Kuraray Co., Ltd.) was hydrogenated in a cyclohexane solvent using palladium-carbon as a catalyst in a hydrogen atmosphere of 2 MPa, and LIR-50 hydrogenated as a saturated hydrocarbon compound (Mn = 30000) Got. The saturated hydrocarbon compound of Example 2 was replaced with the LIR-50 hydrogenated product, the added amount of the saturated hydrocarbon compound was 15% by mass, and the added amount of 12-hydroxystearic acid was added to the LIR-50 hydrogenated product. In contrast, the content was 0.1 parts by mass. Other than that, a developing roller was prepared in the same manner as in Example 1 and evaluated.
[Example 7]
The saturated hydrocarbon compound of Example 3 was replaced with a LIR-50 hydrogenated product, the added amount of the saturated hydrocarbon compound was 50% by mass, and the added amount of 12-hydroxystearic acid was based on the LIR-50 hydrogenated product. The amount was 0.1 parts by mass. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 8]
The saturated hydrocarbon compound of Example 4 was replaced with a LIR-50 hydrogenated product, the amount of the saturated hydrocarbon compound added was 15% by mass, and the amount of 12-hydroxystearic acid added to the LIR-50 hydrogenated product The amount was 5.0 parts by mass. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 9]
The saturated hydrocarbon compound of Example 5 was replaced with the LIR-50 hydrogenated product, the added amount of the saturated hydrocarbon compound was 50% by mass, and the added amount of 12-hydroxystearic acid was added to the LIR-50 hydrogenated product. The amount was 5.0 parts by mass. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 10]
The saturated hydrocarbon compound of Example 2 was replaced with Lucant HC-40 (trade name, manufactured by Mitsui Chemicals, Mn = 1000), the addition amount of the saturated hydrocarbon compound was 15% by mass, and 12-hydroxystearic acid was added. The amount was 0.1 parts by mass with respect to the Lucant HC-40. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 11]
The saturated hydrocarbon compound of Example 3 was replaced with Lucant HC-40, the added amount of the saturated hydrocarbon compound was 50% by mass, and the added amount of 12-hydroxystearic acid was 0.1% with respect to the Lucant HC-40. The part. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 12]
The saturated hydrocarbon compound of Example 4 was replaced with Lucant HC-40, the added amount of the saturated hydrocarbon compound was 15% by mass, and the added amount of 12-hydroxystearic acid was 5.0% with respect to the Lucant HC-40. The part. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 13]
The saturated hydrocarbon compound of Example 5 was replaced with Lucant HC-40, the added amount of the saturated hydrocarbon compound was 50% by mass, and the added amount of 12-hydroxystearic acid was 5.0% with respect to the Lucant HC-40. The part. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 14]
The saturated hydroxycarboxylic acid of Example 1 was 2-hydroxylauric acid. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 15]
The saturated hydroxycarboxylic acid of Example 1 was 20-hydroxyarachidic acid. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 16]
The crosslinked rubber of Example 1 was designated as butadiene rubber BR-150 (trade name, manufactured by Ube Industries). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 17]
The crosslinked rubber of Example 1 was SBR rubber Nipol NS116R (21% bonded styrene, trade name, manufactured by Nippon Zeon Co., Ltd.). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 18]
The crosslinked rubber of Example 1 was NBR rubber Nipol DN401 (18% bonded acrylonitrile amount, trade name, manufactured by Nippon Zeon Co., Ltd.). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 19]
The crosslinked rubber in Example 1 was IR rubber Nipol IR2200 (trade name, manufactured by Nippon Zeon Co., Ltd.). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Example 20]
The crosslinked rubber of Example 1 was butyl rubber butyl 065 (trade name, manufactured by Nippon Butyl Co.). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Comparative Example 1]
The saturated hydrocarbon compound of Example 1 was replaced with Moresco P-40 (trade name, manufactured by Matsumura Oil Research Institute, Mn = 250). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Comparative Example 2]
The saturated hydrocarbon compound of Example 1 was replaced with Claprene LIR-200 (trade name, manufactured by Kuraray Co., Ltd., Mn = 32000). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Comparative Example 3]
The addition amount of Lucant HC-2000 of Example 1 is 10% by mass, the addition amount of 12-hydroxystearic acid is 1.0 part by mass with respect to the Lucant HC-2000, and other methods are the same as in Example 1. A developing roller was prepared and evaluated.
[Comparative Example 4]
The amount of Lucant HC-2000 added in Example 1 was 55% by mass, the amount of 12-hydroxystearic acid was 1.0 parts by mass with respect to Lucant HC-2000, and the other methods were the same as in Example 1. A developing roller was prepared and evaluated.
[Comparative Example 5]
The amount of 12-hydroxystearic acid added in Example 1 was changed to 0.05 parts by mass with respect to Lucant HC-2000. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Comparative Example 6]
The amount of 12-hydroxystearic acid added in Example 1 was changed to 6.0 parts by mass with respect to Lucant HC-2000, and the number of parts added to HC-2000 was 59 parts by mass. Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.
[Comparative Example 7]
A developing roller was prepared and evaluated in the same manner as in Example 1 except that the saturated aliphatic hydroxycarboxylic acid of Example 1 was 10-hydroxydecanoic acid.
[Comparative Example 8]
A developing roller was prepared and evaluated in the same manner as in Example 1 except that the saturated aliphatic hydroxycarboxylic acid of Example 1 was 22-hydroxydocosanoic acid, and other than that.
[Comparative Example 9]
The crosslinked rubber of Example 1 was epichlorohydrin rubber T3106 (trade name, manufactured by Nippon Zeon Co., Ltd.). Other than that, a developing roller was prepared and evaluated in the same manner as in Example 1.

  As described above, according to the present invention, it is possible to provide a developing roller excellent in image formation, in which stability of electric resistance value and suppression of bleed are good, and a decrease in current value of the developing roller that occurs during continuous image formation is suppressed. It becomes possible to do.

1 Conductive Core 2 Elastic Layer 3 Covering Layer

Claims (5)

A developing container that contains toner, a developing roller that is rotatably supported in an opening of the developing container, a developing blade that regulates the amount of toner carried by the developing roller, and a bias applied to the developing blade And a developing device that develops a latent image on the photoreceptor facing the developing roller with toner,
The developing roller has a conductive core, an elastic layer formed on the outer periphery of the conductive core, and a coating layer formed on the outer periphery of the elastic layer,
The elastic layer is
A crosslinked rubber having a polyalkylene structure in the main chain;
A saturated hydrocarbon compound having a number average molecular weight of 300 to 30,000,
A saturated aliphatic hydroxycarboxylic acid having 12 to 20 carbon atoms ;
Carbon black as a conductive agent ,
The saturated hydrocarbon compound is contained in the elastic layer in an amount of 15% by mass to 50% by mass with respect to the total mass of the elastic layer,
Saturated aliphatic hydroxycarboxylic acids are developing apparatus is characterized in that it is contained in the elastic layer below 5.0 part by mass or more 0.1 part by mass with respect to the saturated hydrocarbon compound 100 parts by mass.   The developing device according to claim 1, wherein the crosslinked rubber is ethylene-propylene-diene rubber.   The developing device according to claim 1, wherein the saturated aliphatic hydroxycarboxylic acid is hydroxystearic acid. The developing device according to claim 1, wherein the saturated hydrocarbon compound has a number average molecular weight of 1000 or more and 30000 or less. A toner, a developing container containing the toner, a developing roller, a developing blade for regulating the amount of toner carried by the developing roller, and a means for applying a bias to the developing blade. An electrophotographic apparatus having a developing device that develops a latent image on a photoconductor facing a developing roller, wherein the developing device is the developing device according to any one of claims 1 to 4. An electrophotographic device.

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