JP2010169941A - Charging member, charging device, process cartridge, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging member capable of preventing the occurrence of a crack. <P>SOLUTION: The charging member has: an elastic layer 31; and a surface layer 32 arranged on the elastic layer 31, containing particles 32B for forming recessed and projecting parts on a surface, and having the particles 32B unevenly distributed on a surface side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging member, a charging device, a process cartridge, and an image forming apparatus.

  In recent years, image forming apparatuses such as printers and copiers have been widely used, and technologies relating to various elements constituting the image forming apparatus have also been widely used. Among image forming apparatuses that employ an electrophotographic method, a photosensitive member such as a photosensitive member (image holding member) drum is charged by using a charging device, and an ambient potential is applied on the charged photosensitive member. In many cases, a pattern to be printed is formed by forming an electrostatic latent image having a potential different from that of the electrostatic latent image. The electrostatic latent image formed in this way is developed with toner, and finally recorded. It is transferred onto a recording medium such as paper.

  The charging device is a device that plays an important role of charging the photoconductor. It is a contact charging type charging device that directly contacts the photoconductor to charge the photoconductor, and the vicinity of the photoconductor without contacting the photoconductor. The charging device is roughly classified into two types, that is, a non-contact charging device that charges the photosensitive member by corona discharge or the like. In recent years, there has been an increase in charging devices that employ a contact charging method that generates less chemical substances such as ozone and nitrogen oxides than non-contact charging devices.

As a charging member such as a charging roll provided in a charging device, a charging member having a surface roughness increased by containing particles (filler) has been proposed in order to prevent contamination such as toner adhesion. Specifically, for example, in a charging member having a structure in which a resistive layer is coated or supported on a conductive substrate, the resistive layer has a non-conductive particle near the inner surface near the conductive substrate. In the resistance layer, the non-conductive particles are 1.1 times or more within the range of 10% thickness from the surface side surface compared to the range of 10% thickness on the lower surface side. A charging member distributed at a ratio of 5 times or less has been proposed (see Patent Document 1).
JP-A-2005-300667

  The subject of this invention is providing the charging member which suppressed generation | occurrence | production of a crack.

The invention according to claim 1
An elastic layer;
A surface layer that is disposed on the elastic layer and includes particles for imparting irregularities to the surface, and the particles are unevenly distributed on the surface side;
A charging member.

The invention according to claim 2
The charging member according to claim 1, wherein the particles do not exist in a region within 30% of the average film thickness of the surface layer from the elastic layer side toward the surface side.

The invention according to claim 3
A charging device comprising the charging member according to claim 1.

The invention according to claim 4
An image carrier, and charging means for charging the image carrier,
A process cartridge, wherein the charging means is the charging device according to claim 3.

The invention according to claim 5
An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
With
The image forming apparatus, wherein the charging unit is the charging device according to claim 3.

According to the first aspect of the present invention, the generation of cracks is suppressed as compared with the case where the particles of the surface layer are not unevenly distributed on the surface side.
According to the invention which concerns on Claim 2, generation | occurrence | production of a crack is suppressed compared with the case where the particle | grains of a surface layer exist in the area | region of the elastic layer side.
According to the third aspect of the present invention, charging is performed while suppressing the occurrence of cracks in the charging member as compared with the case without this configuration.
According to the invention which concerns on Claim 4, compared with the case where it does not have this structure, charging is performed, suppressing generation | occurrence | production of the crack of a charging member.
According to the fifth aspect of the present invention, charging is performed while suppressing the occurrence of cracks in the charging member as compared with the case without this configuration.

  Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.

(Charging member)
FIG. 1 is a schematic perspective view showing a charging member according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the charging member according to the present embodiment. FIG. 3 is an enlarged cross-sectional view showing a surface layer in the charging member according to the present embodiment. 2 is a cross-sectional view taken along the line AA in FIG.

  1 and 2, the charging member 121 according to the present embodiment includes, for example, a shaft 30 (core body), an elastic layer 31 disposed on the outer peripheral surface of the shaft 30, and an outer periphery of the elastic layer 31. And a surface layer 32 disposed on the surface. And the surface layer 32 is comprised including resin 32A and particle | grains 32B, as shown in FIG.

  The charging member 121 according to the present embodiment is not limited to the above-described configuration, for example, an adhesive layer (primer layer) disposed between the elastic layer 31 and the shaft 30, or between the elastic layer 31 and the surface layer 32. A configuration may be provided in which a resistance adjusting layer or a migration preventing layer to be disposed and a coating layer (protective layer) disposed on the outer side (outermost surface) of the surface layer 32 are provided.

  The shaft 30 is a conductive rod-like member, and examples of the material thereof include metals such as iron (free-cutting steel), copper, brass, stainless steel, aluminum, nickel, and the like. Examples of the shaft 30 include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The shaft 30 may be a hollow member (cylindrical member) or a non-hollow member.

  The elastic layer 31 includes, for example, an elastic material, a conductive agent, and other additives as necessary.

  Elastic materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide- Examples include allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blend rubbers thereof. Among these, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blended rubbers thereof are desirably used. These elastic materials may be foamed or non-foamed.

  Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of electronic conductive agents include carbon blacks such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; tin oxide, indium oxide, titanium oxide And various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals ; These conductive agents may be used alone or in combination of two or more.

  Here, specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Special Black 550”, “Special Black 6”, “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “MONARCH1000” manufactured by Cabot, Cabot “MONARCH1300” manufactured by Cabot Corporation, “MONARCH1400” manufactured by Cabot Corporation, “MOGUL-L”, “REGAL400R”, etc.

  The addition amount of the conductive agent is not particularly limited, but in the case of the electronic conductive agent, it is preferably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the elastic material. It is more desirable that the amount be in the range of parts by mass or less. On the other hand, in the case of the ionic conductive agent, it is desirable that the amount be in the range of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the elastic material, and 0.5 to 3.0 parts by weight. The following range is more desirable.

  Examples of other additives blended in the elastic layer 31 include a softener, a plasticizer, a curing agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, a coupling agent, and a filler (silica, Examples thereof include materials that can be added to a normal elastic layer such as calcium carbonate).

The thickness of the elastic layer 31 is preferably about 1 mm to 10 mm in terms of average film thickness, and more preferably about 2 mm to 5 mm. The volume resistivity of the elastic layer is preferably 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less.

  As shown in FIG. 3, the surface layer 32 includes a resin 32A, particles 32B, and, if necessary, a conductive agent and other additives. In the surface layer 32, the particles 32B are unevenly distributed on the surface side (unevenly on the outer peripheral surface side of the charging member 121).

  The particles 32B are for blending with the surface layer 32 and for imparting irregularities (specific surface roughness) to the surface of the surface layer 32 (the outer peripheral surface of the charging member 121). The surface of the surface layer 32 is formed by the particles 32B. Concavities and convexities are imparted to the surface.

  The particles 32B are unevenly distributed on the surface side of the surface layer 32 (is unevenly distributed on the outer peripheral surface side of the charging member 121). In particular, the particles 32B are not present on the elastic layer side of the surface layer 32. Be present on the side). Specifically, for example, the particle 32B is within 30% (desirably within 40%, more desirably within 50%) with respect to the average film thickness of the surface layer 32 from the elastic layer 31 side to the surface side. It is preferable that it does not exist in the area. That is, as shown in FIG. 3, in the surface layer 32, the particle 32 </ b> B is in a region where the distance T2 from the contact surface of the elastic layer 31 along the thickness direction is within 30% of the average film thickness T1 of the surface layer 32. It should not exist.

  Here, a piece (5 mm square) was cut out from the charging member 121 with a single-edged knife, and the surface layer of this piece was observed with a laser microscope (device name: OLS1100 manufactured by Olympus Corporation). The thickness of the thickest part of the surface layer, and the most of the region where particles (filler) do not exist on the elastic layer side (region within the distance T2 from the contact surface of the elastic layer 31 along the thickness direction of the surface layer) Each thin thickness is measured, and the average value obtained by repeating this 10 times is the surface layer average film thickness T1, the area where particles (fillers) are not present (within the distance T2 from the contact surface of the elastic layer 31 along the thickness direction of the surface layer) Area) T2.

  In addition, as a method of unevenly distributing the particles 32B in the surface layer 32, for example, after forming a base surface layer on the elastic layer using a coating solution (composition) for forming a surface layer that does not contain the particles 32B, A method of forming a particle-containing surface layer on the base surface layer using a coating solution (composition) for forming a surface layer in which the particles 32B are blended may be mentioned.

The particles 32B may be either conductive particles or non-conductive particles, but non-conductive particles are preferable. Examples of the conductive particles include particles of the materials mentioned as the conductive agent blended in the elastic layer 31. Non-conductive particles include resin particles (polyimide resin particles, methacrylic resin particles, polystyrene resin particles, fluorine resin particles, silicone resin particles, etc.), inorganic particles (clay particles, kaolin particles, talc particles, silica particles, alumina particles, etc.) ), Or ceramic particles. The particle 32B may be a particle made of the same kind of resin as the resin 32A. This improves the compatibility between the particle 32B and the resin 32A, and increases the adhesion between the particle 32B and the resin 32A.
Here, “conductive” means that the volume resistivity is 10 ¹³ Ωcm, and “non-conductive” means that the volume resistivity is 10 ¹³ Ωcm or more. The same applies to other cases.

  The volume average particle diameter of the particles 32B is desirably 1.5 μm or more and 15 μm or less, and more desirably 2.5 μm or more and 12 μm or less. When the volume average particle diameter of the particles 32B is in the above range, it is easy to obtain a specific ten-point average surface roughness Rz for the surface layer 32. The volume average particle diameter of the particles 32B is a value measured using a Coulter counter TA-II type (manufactured by Coulter). In this case, measurement is performed using an optimum aperture according to the particle size level of the particles. The particles 32B may be spherical or irregular.

Here, the relationship between the volume average particle diameter t of the particles 32B and the average film thickness T1 of the surface layer 32 is
It is desirable to satisfy the formula: 0.25 × T1 ≦ t ≦ 0.6 × T1,
It is more desirable to satisfy the formula: 0.35 × T1 ≦ t ≦ 0.5 × T1. When this relationship is satisfied, it becomes easy to obtain a specific ten-point average surface roughness Rz for the surface layer 32.

  The blending amount of the particles 32B is desirably 5 parts by mass or more and 60 parts by mass or less, more desirably 15 parts by mass or more and 55 parts by mass or less, and further desirably 25 parts by mass or more and 50 parts by mass or less with respect to 100 parts of the resin 32A. It is below mass parts. When the blending amount of the particles 32B is in the above range, it is easy to obtain a specific ten-point average surface roughness Rz for the surface layer 32.

  On the other hand, as the resin 32A, acrylic resin, cellulose resin, polyamide resin, copolymer nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, styrene butadiene resin, melamine resin, epoxy resin, urethane Examples thereof include resins, silicone resins, fluororesins (for example, tetrafluoroethylene perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, polyvinylidene fluoride, etc.), urea resins, and the like. Here, the copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and other polymer units included in the copolymer include: , 6 nylon, 66 nylon and the like. Further, as the resin 32A, an elastic material blended in the elastic layer 31 may be applied.

  Examples of the conductive agent blended in the surface layer 32 include the conductive agent blended in the elastic layer 31. As other additives, for example, conductive agents, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents and the like are usually added to the surface layer. Materials to be obtained are mentioned.

The thickness (overall thickness) of the surface layer 32 is preferably 7 μm or more and 25 μm or less in terms of average film thickness. The volume resistivity of the surface layer is preferably 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less.

  The charging member 121 according to the present embodiment is, for example, applied to the outer peripheral surface of the shaft 30, for example, a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating. The elastic layer 31 and the surface layer 32 are sequentially formed on the outer peripheral surface of the shaft 30 using a method or the like.

  The charging member 121 according to this embodiment preferably has a 10-point average surface roughness Rz of 3 μm or more and 12 μm or less, and 7 μm or more and 12 μm or less, on the surface thereof (the surface of the surface layer 32 provided by the particles 32B). It is more desirable that it is 10 μm or more and 12 μm or less. By setting within this range, it becomes difficult for foreign matters such as toner and external additives to adhere to the surface layer 32, and the contamination resistance becomes high. If the ten-point average surface roughness Rz is less than 3 μm, foreign matters such as toner and external additives may adhere. When the ten-point average surface roughness Rz is larger than 12 μm, toner and paper powder and the like are likely to accumulate in the uneven portions, and abnormal discharge is likely to occur locally, resulting in image defects such as white spots. There is.

  The ten-point average surface roughness Rz is the surface roughness defined in JIS B0601 (1994). The ten-point average surface roughness Rz can be measured using a surface roughness measuring instrument or the like. In the present invention, however, a contact-type surface roughness measuring device (Surfcom 570A) is used in an environment of 23 ° C. and 55 RH%. Manufactured by Tokyo Seimitsu Co., Ltd.). When measuring the surface roughness, the measurement distance was 2.5 mm, and the tip of the contact needle was diamond (5 μmR, 90 ° cone), and the average value was measured three times repeatedly at different locations. The ten-point average surface roughness Rz was obtained.

  In the charging member 121 according to the present embodiment described above, the particles 32 </ b> B for imparting unevenness to the surface are blended unevenly on the surface side of the surface layer 32. Thereby, in the surface layer 32, the particle | grain 32B which exists in the elastic layer side does not exist, or decreases, and the film | membrane comprised by components (resin component) other than particle | grains 32B on the elastic layer side of the surface layer 32 is more than fixed. Secured with thickness. For this reason, since the fall of the local film | membrane intensity | strength of a surface layer is suppressed, generation | occurrence | production of the crack of a surface layer is suppressed. As a result, the small amount of particles 32 </ b> B gives a specific surface roughness to the surface of the charging member, and also suppresses contamination with respect to toner and a decrease in chargeability.

(Charging device)
Hereinafter, the charging device according to the present embodiment will be described. FIG. 4 is a schematic perspective view of the charging device according to the present embodiment. The charging device according to the present embodiment is a form in which the charging member according to the present embodiment is applied as a charging member.

  As shown in FIG. 4, the charging device 12 according to the present embodiment is arranged such that, for example, the charging member 121 and the cleaning member 122 are in contact with each other with a specific biting amount. The axial ends of the shaft 30 of the charging member 121 and the shaft 122A of the cleaning member 122 are held by conductive bearings 123 (conductive bearings) so that the respective members can rotate. A power supply 124 is connected to one of the conductive bearings 123. Note that the charging device according to the present embodiment is not limited to the above-described configuration, and may be a form that does not include the cleaning member 122, for example.

  The cleaning member 122 is a cleaning member for cleaning the surface of the charging member 121, and is configured in a roll shape, for example. The cleaning member 122 includes, for example, a shaft 122A and an elastic layer 122B on the outer peripheral surface of the shaft 122A.

  The shaft 122A is a conductive rod-like member, and examples of the material thereof include metals such as iron (free-cutting steel and the like), copper, brass, stainless steel, aluminum, and nickel. Examples of the shaft 122A include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The shaft 122A may be a hollow member (cylindrical member) or a non-hollow member.

  The elastic layer 122B is made of a foam having a porous three-dimensional structure. The elastic layer 122B preferably has elasticity, with cavities and concavo-convex portions (hereinafter referred to as cells) inside and on the surface. The elastic layer 122B is made of polyurethane, polyethylene, polyamide, olefin, melamine or polypropylene, NBR (acrylonitrile-butadiene copolymer rubber), EPDM (ethylene-propylene-diene copolymer rubber), natural rubber, styrene butadiene rubber, chloroprene, silicone, It includes a foamable resin material such as nitrile or a rubber material.

  Among these foamable resin materials or rubber materials, foreign substances such as toner and external additives are efficiently cleaned by driven sliding friction with the charging member 121, and at the same time, the cleaning member 122 is formed on the surface of the charging member 121. In order to prevent scratches due to rubbing and to prevent tearing and breakage from occurring over a long period of time, polyurethane that is strong against tearing and tensile strength is particularly preferably applied.

  The polyurethane is not particularly limited. For example, polyol (for example, polyester polyol, polyether polyester, acrylic polyol, etc.) and isocyanate (2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4, 4-diphenylmethane diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, etc.), and reaction products of these chain extenders (for example, 1,4-butanediol, trimethylolpropane, etc.) Good. Polyurethane is generally foamed using a foaming agent (water or an azo compound (azodicarbonamide, azobisisobutyronitrile, etc.).

  The number of cells per 25 mm (number / 25 mm) of the elastic layer 122B is preferably 20/25 mm or more and 80/25 mm or less, more preferably 30/25 mm or more and 80/25 mm or less, and 30/25 mm or more. It is particularly desirable that it is 50/25 mm or less.

  The hardness of the elastic layer 122B is preferably 100N to 500N, more preferably 100N to 400N, and particularly preferably 150N to 400N.

  The conductive bearing 123 is a member that holds the charging member 121 and the cleaning member 122 integrally and rotatably, and also holds an inter-axis distance between the members. The conductive bearing 123 may be of any material and form as long as it is made of a conductive material. For example, a conductive bearing or a conductive sliding bearing is applied.

  The power supply 124 is a device that charges the charging member 121 and the cleaning member 122 with the same polarity by applying a voltage to the conductive bearing 123, and a known high-voltage power supply device can be used.

  In the charging device 12 according to the present embodiment, the charging member 121 and the cleaning member 122 are charged to the same polarity by applying a voltage from the power source 124 to the conductive bearing 123. As a result, foreign matter (for example, toner or external additives) on the surface of the image carrier is prevented from accumulating on the surfaces of the cleaning member 122 and the charging member 121 and can be transferred to the image carrier, and the foreign matter is collected by the image carrier cleaning device. Is done. Therefore, accumulation of dirt on the charging member 121 and the cleaning member 122 is suppressed over a long period of time, and charging performance is maintained.

(Image forming device, process cartridge)
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and the image carrier. Developing means for developing the latent image formed on the surface of the toner image with toner to form a toner image, and transfer means for transferring the toner image formed on the surface of the image carrier to a recording medium. The charging device according to the present embodiment is applied as the charging means (charging device).

  On the other hand, the process cartridge according to this embodiment includes, for example, an image holding member that is detached from the image forming apparatus having the above-described configuration, and a charging unit that charges the image holding member. The charging device according to the present embodiment is applied as the charging unit. The process cartridge according to the present embodiment includes, as necessary, developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image, and a toner image formed on the surface of the image carrier. At least one selected from the group consisting of a transfer unit that transfers the toner to a recording medium and a cleaning unit that removes residual toner on the surface of the image carrier after transfer.

  Next, an image forming apparatus and a process cartridge according to the present embodiment will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment. FIG. 6 is a schematic configuration diagram showing a process cartridge according to the present embodiment.

  As shown in FIG. 5, the image forming apparatus 101 according to the present embodiment includes an image carrier 10, a charging device 12 that charges the image carrier around the image carrier 10, and an image carrier charged by the charging device 12. An exposure device 14 that exposes 10 to form a latent image, a developing device 16 that develops the latent image formed by the exposure device 14 with toner to form a toner image, and a toner image that is formed by the developing device 16 A transfer device 18 for transferring to A, and a cleaning device 20 for removing residual toner on the surface of the image carrier 10 after transfer. Further, a fixing device 22 for fixing the toner image transferred to the recording medium A by the transfer device 18 is provided.

  The image forming apparatus 101 according to the present embodiment includes, as the charging device 12, for example, a charging member 121, a cleaning member 122 disposed in contact with the charging member 121, and both axial ends of the charging member 121 and the cleaning member 122. The charging device according to the present embodiment, in which a conductive bearing 123 (conductive bearing) that holds each member so as to be rotatable and a power source 124 connected to one of the conductive bearings 123 are disposed. Has been applied.

  On the other hand, in the image forming apparatus 101 of the present embodiment, known configurations are conventionally applied as the components of the electrophotographic image forming apparatus, except for the charging device 12 (charging member 121). Hereinafter, an example of each configuration will be described.

  The image carrier 10 is not particularly limited, and a known photoreceptor can be used. An organic photoreceptor having a so-called function separation type structure in which a charge generation layer and a charge transport layer are separated is preferably used. In addition, the image carrier 10 is preferably applied to a photoconductor whose surface layer is made of a siloxane resin or a phenol resin having a charge transporting property and a crosslinked structure.

  As the exposure apparatus 14, for example, a laser optical system, an LED array, or the like is applied.

  For example, the developing device 16 brings a toner image onto the latent image on the surface of the image carrier 10 by bringing a developer carrier having a developer layer formed on the surface thereof into contact with or close to the image carrier 10. A developing device to be formed. As a developing method of the developing device 16, a developing method using a two-component developer is suitably applied as a known method. Examples of the developing method using the two-component developer include a cascade method and a magnetic brush method.

  Examples of the transfer device 18 include a non-contact transfer method such as corotron and scorotron, and a contact transfer method in which a conductive transfer roll is brought into contact with the image carrier 10 via the recording medium A to transfer a toner image to the recording medium A. Either may be applied.

  The cleaning device 20 is, for example, a member that removes toner, paper dust, dust, and the like adhering to the surface by bringing a cleaning blade into direct contact with the surface of the image carrier 10. As the cleaning device 20, a cleaning brush, a cleaning roll, or the like may be applied in addition to the cleaning blade.

  As the fixing device 22, a heat fixing device using a heat roll is suitably applied. The heat fixing device includes, for example, a fixing roller in which a so-called release layer is formed of a heat-resistant resin coating layer or a heat-resistant rubber coating layer on the outer peripheral surface thereof with a heater lamp for heating inside a cylindrical metal core, A pressure roller or a pressure belt that is disposed in contact with the fixing roller at a specific contact pressure and has a heat-resistant elastic body layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. . The fixing process of the unfixed toner image is performed, for example, by inserting the recording medium A onto which the unfixed toner image is transferred between a fixing roller and a pressure roller or a pressure belt, and binding resin in the toner, Fixing by heat melting of additives and the like.

  The image forming apparatus 101 according to the present embodiment is not limited to the above configuration. For example, an intermediate transfer type image forming apparatus using an intermediate transfer member and an image forming unit that forms toner images of each color are arranged in parallel. A so-called tandem image forming apparatus may be used.

  On the other hand, as shown in FIG. 6, the process cartridge according to the present embodiment includes an opening 24A for exposure, an opening 24B for static elimination exposure, and a mounting rail 24C in the image forming apparatus shown in FIG. By the housing 24, the image carrier 10, the charging device 12 for charging the image carrier, the developing device 16 for developing the latent image formed by the exposure device 14 with toner and forming a toner image, and after the transfer And a cleaning device 20 that removes residual toner on the surface of the image holding body 10 and is integrally assembled and held. The process cartridge 102 is detachably attached to the image forming apparatus 101 shown in FIG.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by the following Example. Unless otherwise specified, “part” means “part by mass”.

[Example 1]
(Preparation of charging roll)
-Formation of elastic layer-
Elastic material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber) 15 parts by mass of conductive agent (carbon black Asahi Thermal: manufactured by Asahi Carbon Co., Ltd.) and vulcanizing agent (sulfur 200 mesh: Tsurumi Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller DM: manufactured by Ouchi Shinsei Chemical Co., Ltd.): a mixture of 2.0 parts by mass and the like is kneaded with an open roll, and a shaft made of SUS303 and having a diameter of 8 mm. (Conductive support) An elastic layer having a thickness of 7 mm was formed on the outer peripheral surface of the outer peripheral surface through an adhesive layer using a press molding machine to obtain a roll having a diameter of 15 mm. Thereafter, a conductive elastic roll having a diameter of 14 mm having an elastic layer having a thickness of 6 mm was obtained by polishing.

-Formation of surface layer-
Polymer material (saturated copolymer polyester resin solution) Curing agent (amino resin solution Super Becamine G-821-60: manufactured by Dainippon Ink & Chemicals, Inc.): 26.3 parts by mass, conductive agent (100 parts by mass) (Carbon black) The mixture added with 10 parts by mass was dispersed with a bead mill and diluted with methyl ethyl ketone to obtain a dispersion. Then, the dispersion was dip-coated on the surface of the conductive elastic roll and dried by heating at 180 ° C. for 20 minutes to obtain a base surface layer (particle-free surface layer) having a thickness of 3.8 μm.

Next, a dispersion liquid in which 30 parts by mass of a polystyrene filler (volume average particle diameter 4.1 μm) is dispersed with respect to 100 parts by mass of the dispersion liquid is dip-coated on the surface of a conductive elastic roll having a base surface layer. A particle-containing surface layer was formed by heating at 30 ° C. for 30 minutes so that the thickness of the entire surface layer was 8.2 μm.
In this way, a charging roll was obtained.

(Evaluation of charging roll)
-Observation of surface layer-
As described above, the average thickness T1 of the surface layer and the region (region within the distance T2 from the contact surface of the elastic layer 31 along the thickness direction of the surface layer) T2 in which particles (filler) do not exist were obtained.

-Crack and stripe evaluation-
The above charging roll was incorporated into a toner cartridge of a Fuji Xerox color copier DocuCenter Color a450, and after 10,000 sheets were printed, cracks on the charging roll were observed. If there was no crack, it was marked as ◯, if a crack with a width of 1 μm or less occurred, Δ, and if a crack with a width of 1 μm or more had occurred, it was marked as x. In the image on the 10000th sheet, “O” was obtained when no streak due to dirt on the charging roll was generated, “Δ” was observed when a slight streak was observed, and “X” was observed when a dark streak was generated.

[Examples 2 to 7]
According to Table 1, the thickness of the base surface layer (particle-free surface layer) and the average film thickness of the surface layer (the thickness of the entire surface layer) were determined by dip coating of each dispersion in the formation of the surface layer. A charging roll was prepared in the same manner as in Example 1 except that the coating thickness was adjusted. The obtained charging roll was evaluated in the same manner as in Example 1.

[Comparative Example 1]
A charging roll in the same manner as in Example 1 except that only the base surface layer (particle-free surface layer) was formed so as to have the average thickness of the surface layer (the thickness of the entire surface layer) according to Table 1. Was made. The obtained charging roll was evaluated in the same manner as in Example 1.

  From the above results, it can be seen that in this example, the occurrence of cracks and the occurrence of image streaks are suppressed as compared with the comparative example.

It is a schematic perspective view which shows the charging member which concerns on this embodiment. It is a schematic sectional drawing of the charging member which concerns on this embodiment. It is an expanded sectional view which shows the surface layer in the charging member which concerns on this embodiment. 1 is a schematic perspective view of a charging device according to an embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment.

DESCRIPTION OF SYMBOLS 10 Image carrier 12 Charging device 14 Exposure device 16 Development device 18 Transfer device 20 Cleaning device 22 Fixing device 24 Case 24A Opening 24B Opening 24C Mounting rail 30 Shaft 31 Elastic layer 32 Surface layer 32A Resin 32B Particle 101 Image formation Device 102 Process cartridge 121 Charging member 122 Cleaning member 123 Conductive bearing 122A Shaft 122B Elastic layer 124 Power supply

Claims (5)

An elastic layer;
A surface layer that is disposed on the elastic layer and includes particles for imparting irregularities to the surface, and the particles are unevenly distributed on the surface side;
A charging member.   The charging member according to claim 1, wherein the particles do not exist in a region within 30% of the average film thickness of the surface layer from the elastic layer side toward the surface side.   A charging device comprising the charging member according to claim 1. An image carrier, and charging means for charging the image carrier,
A process cartridge, wherein the charging means is the charging device according to claim 3. An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
With
The image forming apparatus, wherein the charging unit is the charging device according to claim 3.

Images