JP7273624B2 - IMAGE CARRIER CLEANING ROLLER AND IMAGE FORMING APPARATUS - Google Patents

Description

The present invention relates to an image carrier cleaning roller and an image forming apparatus.

Laser printers, copiers, video printers, facsimiles, multi-function machines, and the like employ various image forming apparatuses using an electrophotographic system. For the purpose of forming high-quality images, an electrophotographic image forming apparatus is provided with a cleaning device that removes developer that has not been transferred or transported as desired or that adheres to the developer. There is Such a cleaning device conveys, for example, developer remaining on an image carrier, that is, a photosensitive member, developer remaining on an intermediate transfer belt in an intermediate transfer type image forming apparatus, or a recording medium in a tandem color image forming apparatus. It is used to remove the developer and the like adhering to the transfer transport belt (also referred to as the recording body transport belt).

Such a cleaning device includes a blade system equipped with a cleaning blade for scraping off the developer remaining or adhering to the surface with a cleaning blade or the like, and a cleaning device receiving the developer remaining or adhering to the surface by contacting or pressing the surface. There are a roller system equipped with a cleaning roller, a combination system using both a blade system and a roller system, and the like.

A cleaning roller generally has a foamed elastic layer on its outermost surface, and various studies have been made to maintain the cleaning performance of this foamed elastic layer for a long period of time. For example, Patent Document 1 proposes a cleaning roller provided with a foamed elastic layer containing glass beads. According to this cleaning roller, it is possible to maintain the independent cell state for a long period of time, so that high durable printing performance is exhibited.

JP 2012-242402 A

However, even when a known image bearing member cleaning roller is used, when image formation is performed for a long period of time, minute white spots may occur continuously in the conveying direction of the recording medium. For this reason, image bearing member cleaning rollers are required to form high-quality images over a long period of time.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a cleaning roller for an image bearing member and an image forming apparatus equipped with the cleaning roller, which enables high-quality image formation over a long period of time. do.

As a result of intensive studies by the present inventors, it was found that white spots are caused by fine particles containing fine silica particles contained in the toner remaining on the surface of the image carrier. In other words, it was found that the conventional image bearing member cleaning roller could remove the developer, but could not completely remove the extremely fine particles in some cases.
Accordingly, the inventors of the present invention have solved the above problems by forming a coating layer having irregularities of fine particles on the cell walls of the foamed elastic layer to provide a structure in which both toner particles and fine particles such as silica particles can be removed. I found that it can be done, and arrived at the present invention.
That is, the present invention provides an image carrier cleaning roller comprising a shaft and a foamed elastic layer formed on the outer peripheral surface of the shaft, wherein the foamed elastic layer has a cell diameter of 50 μm or more and 300 μm or less, A coating layer containing a base resin and fine particles is provided on at least the cell walls of the foamed elastic layer, the surface of the coating layer has irregularities formed by the fine particles, and the thickness of the coating layer is 5 μm or more and 50 μm or less. and the average particle diameter of the fine particles is 4 μm or more and 25 μm or less.

The fine particles are preferably made of urethane, acryl, silicone, polystyrene, ester polyimide, or polyamide.

The Asker C hardness of the surface of the image carrier cleaning roller is preferably 30 or more and 50 or less.

The base resin of the coating layer is preferably urethane resin or silicone resin.

An image forming apparatus of the present invention includes an image carrier on which an electrostatic latent image is formed, and an image carrier cleaning roller of the present invention arranged so as to be in contact with the image carrier.

According to the present invention, it is possible to provide an image carrier cleaning roller and an image forming apparatus that enable high-quality image formation over a long period of time.

1 is a perspective view of an image carrier cleaning roller of the present invention; FIG. FIG. 2 is a schematic cross-sectional view for explaining a coating layer of the image carrier cleaning roller of the present invention; 1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus provided with an image carrier cleaning roller of the present invention; FIG.

Embodiments of the present invention will be described in detail below, but the following embodiments are presented for the purpose of illustration, and the present invention is not limited to the embodiments shown below.

[Image carrier cleaning roller]
FIG. 1 is a perspective view showing an embodiment of an image carrier cleaning roller of the present invention.
As shown in FIGS. 1 and 2, the image carrier cleaning roller 10 of the present invention includes a shaft 11 and a foamed elastic layer 12 formed on the outer peripheral surface of the shaft 11. A coating layer 13 containing a base resin and fine particles 15 is provided on at least the cell walls 12a.

The image carrier cleaning roller 10 has a relatively low hardness. Specifically, the Asker C hardness is preferably 30 or more and 50 or less, more preferably 35 or more and 48 or less. When the Asker C hardness is within the above range, the image carrier cleaning roller 10 can ensure a sufficient nip width with the image carrier with which it contacts or presses. In addition, the stress or damage given to the image carrier, as well as foreign matter remaining or adhering to the image carrier, especially the developer, is small, and damage to the image carrier and destruction of the developer are prevented, and sufficient cleaning performance is exhibited. Therefore, the quality of the formed image is not degraded. Asker C hardness (1 kg load) can be measured according to JIS K6253.
The Asker C hardness of the image bearing member cleaning roller 10 of the present invention is determined, for example, by the types of silicone rubber, foaming agent, and fine particles contained in the silicone rubber composition forming the foamed elastic layer 12, and their compounding amounts. can be adjusted by changing

The image carrier cleaning roller 10 preferably has an electrical resistance value of 104.0Ω or more and 108.0Ω or less (4.0Ω or more and 8.0Ω or less in log value), and an electrical resistance of 106Ω or more and 107Ω or less. It is more preferable to have a value. The electric resistance value is the electric resistance value before the image carrier cleaning roller 10 is used. When the electric resistance value is within the above range, the electrical removal ability to electrically remove foreign matters, especially the developer, remaining on or adhering to the image carrier from the image carrier increases, further improving the cleaning performance. can be made
The electric resistance value is measured, for example, by using an electric resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A, manufactured by Advantest Co., Ltd.), placing the image carrier cleaning roller 10 horizontally, and measuring a thickness of 5 mm, a width of 30 mm, and a width of 30 mm. , a state in which a gold-plated plate having a length on which the entire image carrier cleaning roller 10 can be placed is used as an electrode, and a load of 500 g is supported on both ends of the shaft 11 of the image carrier cleaning roller 10 (total Load 1000 g), apply DC 100 V between the shaft 11 and the electrode, read the value of the electrical resistance meter after 1 second, and use this value as the electrical resistance value. can. The electric resistance value of the image carrier cleaning roller 10 can be adjusted by adjusting the content of a conductivity-imparting agent, which will be described later, contained in the foamed elastic layer 12 and the coating layer 13 .

(Shaft)
As the shaft 11, preferably, a conductive shaft 11 used in a known image carrier cleaning roller 10 can be used. The shaft 11 is preferably made of, for example, at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. The shaft body 11 made of such a metal is generally also known by the name of "metal core".

The shaft 11 may contain insulating resin. Examples of insulating resins include thermoplastic resins and thermosetting resins. The shaft 11 may include, for example, a core made of insulating resin and a plated layer provided on the core. Such a shaft 11 can be obtained, for example, by plating a core made of an insulating resin to make it conductive. Alternatively, the shaft 11 may be made of a conductive resin obtained by blending carbon black black, metal powder, or the like as a conductivity-imparting agent with a thermoplastic resin, a thermosetting resin, or the like.

The shape of the shaft 11 is preferably, for example, rod-like or tubular. The cross-sectional shape of the shaft 11 may be, for example, circular, elliptical, or non-circular such as polygonal. The outer peripheral surface of the shaft 11 may be subjected to a cleaning treatment, a degreasing treatment, a primer treatment, or the like, in order to improve adhesion with the foamed elastic layer 12 .

(Foam elastic layer)
The foamed elastic layer 12 constituting the image carrier cleaning roller 10 is formed on the outer peripheral surface of the shaft 11 as a foamed elastic layer having cells 14 therein. When the foamed elastic layer 12 has cells, the Asker C hardness of the image carrier cleaning roller 10 can be adjusted within the above range, and a sufficient nip width can be secured. 10 can exhibit high cleaning performance. Here, the cells 14 in the foamed elastic layer 12 refer to hollow regions generated by foaming or decomposition of a foaming agent contained in the silicone rubber composition capable of forming the foamed elastic layer 12 . A plurality of cells in the foamed elastic layer 12 may be in a state of not contacting or communicating with other cells 14 (referred to as an independent cell state), or a state of communicating with other cells 14 (communicated cell state). ), or a state in which the closed cell state and the open cell state coexist. Preferably.

The cells 14 normally exist inside the foamed elastic layer 12, and after the foamed elastic layer 12 is molded, there are almost no cells open on the outer peripheral surface and end surfaces thereof. If the outer peripheral surface of the foamed elastic layer 12 formed by foaming and curing a rubber composition described later is subjected to a grinding step, a polishing step, and/or a cutting step as a finishing step, etc., the foamed elastic layer 12 exists in the vicinity of the outer peripheral surface of the foamed elastic layer 12. The cells 14 are opened on the outer peripheral surface of the foamed elastic layer 12 after treatment. The cells 14 open on the surface generally have an opening diameter and depth substantially equal to the average cell diameter of the cells 14, which will be described later.

The average cell diameter of the cells 14 of the foamed elastic layer 12 is 50 μm or more and 300 μm or less. The average cell diameter is preferably 100 μm or more and 300 μm or less, more preferably 200 μm or more and 300 μm or less. When the average cell diameter is within the above range, the image carrier cleaning roller 10 can easily remove the developer from the image carrier when it is attached to the cleaning device.
The average cell diameter of the cells 14 is about 20 mm ² on any cut surface of the image carrier cleaning roller 10 provided with the coating layer 13 . The average length obtained by measuring the maximum length of the opening in each cell existing in the cell at 20 points and arithmetically averaging the measured maximum lengths can be obtained.

The expansion ratio of the foamed elastic layer 12 is preferably 200% or more and 350% or less, more preferably 250% or more and 300% or less. When the foaming ratio of the foamed elastic layer 12 is within the above range, for example, the Asker C hardness can be adjusted within the above range, and a sufficient nip width can be secured. performance can be demonstrated.
The expansion ratio can be calculated by measuring the volume and mass of the foamed elastic layer 12 by a conventional method. In the foamed elastic layer 12, the average cell diameter and expansion ratio can be adjusted by the foaming agent contained in the silicone rubber composition described later forming the foamed elastic layer 12 or the curing conditions of the silicone rubber composition.

The density of the foamed elastic layer 12 is preferably 0.2 to 0.7 (g/cm ³ ), more preferably 0.3 to 0.6 (g/cm ³ ). When the density is within the above range, the effects of the present invention can be further enhanced. The density of the foamed elastic layer 12 can be measured by an electronic densitometer (underwater substitution method, water temperature: 23°C).

The shape of the foamed elastic layer 12 is not particularly limited. For example, as shown in FIG. It may be a so-called crown shape adjusted to be larger than the outer diameter, or a so-called inverted crown shape adjusted so that the outer diameter at the center is smaller than the outer diameter at both ends. may

The thickness of the foamed elastic layer 12 is not particularly limited, and can usually be adjusted to 2 mm or more and 20 mm or less.

The foamed elastic layer 12 is formed by heating and curing a silicone rubber composition on the outer peripheral surface of the shaft 11 . The silicone rubber composition for forming the foamed elastic layer 12 preferably contains rubber, a conductivity-imparting agent, a foaming agent, and optionally various additives.

Examples of silicone rubber compositions include addition-curable millable conductive silicone rubber compositions.

- Addition Curable Millable Conductive Silicone Rubber Composition -
The addition-curable millable conductive silicone rubber composition comprises, for example, (A) an organopolysiloxane represented by the following average compositional formula (1), (B) a filler, (C) a conductivity-imparting agent, and (D) a foaming agent. Those containing are preferred.
R ¹ _n SiO _(4−n)/2 (1)
In formula (1), n represents a positive number of 1.95 or more and 2.05 or less. Moreover, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less.

Examples of R ¹ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, cycloalkyl groups such as cyclohexyl group, vinyl group, allyl group, butenyl group and hexenyl group. Examples include alkenyl groups, aryl groups such as phenyl and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. Also, R ¹ may be a group in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with a substituent. Substituents may be, for example, halogen atoms, cyano groups, and the like. Hydrocarbon groups having a substituent include, for example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like.

(A) Organopolysiloxane has a molecular chain end which is a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, a trivinylsilyl group, or the like. It is preferably blocked with a trialalkylsilyl group or the like.

(A) Organopolysiloxane preferably has two or more alkenyl groups in the molecule. (A) Organopolysiloxane preferably has 0.001 mol % or more and 5 mol % or less (more preferably 0.01 mol % or more and 0.5 mol % or less) of alkenyl groups in R ¹ . (A) A vinyl group is particularly preferable as the alkenyl group possessed by the organopolysiloxane.

(A) Organopolysiloxane is obtained, for example, by cohydrolytic condensation of one or more organohalosilanes, or by ring-opening polymerization of a cyclic polysiloxane such as a siloxane trimer or tetramer. can be obtained by (A) Organopolysiloxane may be basically linear diorganopolysiloxane, and may be partially branched. Also, (A) organopolysiloxane may be a mixture of two or more different molecular structures.

(A) The organopolysiloxane preferably has a kinematic viscosity at 25° C. of 100 cSt or more, more preferably 100,000 cSt or more and 1,0000,000 cSt or less. The degree of polymerization of (A) organopolysiloxane is preferably, for example, 100 or more, and more preferably 3,000 or more and 10,000 or less.

(B) Fillers include, for example, silica-based fillers. Silica-based fillers include, for example, fumed silica and precipitated silica.

As the silica-based filler, a surface-treated silica-based filler surface-treated with a silane coupling agent represented by R ² Si(OR ³ ) ₃ can be preferably used. Here, R ² may be a group having a vinyl group or an amino group, such as glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group and the like. ^R3 may be an alkyl group, such as a methyl group, an ethyl group, and the like. Silane coupling agents are readily available, for example, under the trade names of "KBM1003" and "KBE402" manufactured by Shin-Etsu Chemical Co., Ltd. A surface-treated silica-based filler can be obtained by treating the surface of a silica-based filler with a silane coupling agent according to a conventional method. As the surface-treated silica-based filler, a commercially available product may be used. M. Trade name "Zeothix 95" manufactured by HUBER Corporation and the like can be mentioned.

The amount of the silica-based filler compounded is preferably 11 parts by mass or more and 39 parts by mass or less, more preferably 15 parts by mass or more and 35 parts by mass or less per 100 parts by mass of the organopolysiloxane (A). The average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, more preferably 2 μm or more and 40 μm or less. The average particle size of the silica-based filler can be measured as a median size using a particle size distribution analyzer based on a laser beam diffraction method.

The amount of the (C) conductivity-imparting agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the organopolysiloxane (A). The amount of the (C) conductivity-imparting agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less per 100 parts by mass of the (A) organopolysiloxane.

(D) Foaming agents include azobis-isobutyronitrile. (D) The content of the foaming agent is preferably 12 parts by mass or less, and 0.8 parts by mass or more and 7.0 parts by mass or less with respect to a total of 100 parts by mass of (A) organopolysiloxane and (B) filler. is preferably

-Other ingredients-
Additives other than (A) to (D) may be further contained. Additives include, for example, auxiliaries (chain extenders, cross-linking agents, etc.), catalysts, dispersants, anti-aging agents, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat-resistant property improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, release agents, solvents and the like.

Specific examples of the additive include (A) dimethylsiloxane oil having a lower degree of polymerization than organopolysiloxane, polyether-modified silicone oil, silanol, diphenylsilanediol and α,ω-dimethylsiloxanediol, both terminal silanol group-capped. Dispersants such as low-molecular-weight siloxane and silane can be used. Specific examples of additives include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. As additives, various carbon functional silanes, various olefinic elastomers, and the like may be used for improving adhesiveness, molding processability, and the like.

The foamed elastic layer 12 is formed on the outer peripheral surface of the shaft 11 by performing heat curing and molding simultaneously or continuously by a known molding method. The method of curing the rubber composition may be any method as long as the heat necessary for curing the rubber composition can be applied. It is not particularly limited. For example, when the rubber composition is an addition-curable millable conductive silicone rubber composition, for example, extrusion molding or the like can be selected.

The heating temperature for curing the rubber composition is preferably 100° C. or higher and 500° C. or lower, more preferably 120° C. or higher and 300° C. or lower, in the case of the addition-curable millable conductive silicone rubber composition. The heating time is preferably several seconds to 1 hour, more preferably 10 seconds to 35 minutes. In the case of the addition-curable millable conductive silicone rubber composition, for example, the curing conditions are selected at 100° C. or higher and 200° C. or lower for about 1 hour or longer and 20 hours or shorter. Further, the rubber composition can be foamed and cured by a known method to easily form a sponge-like elastic layer having cells.

The thickness of the foamed elastic layer 12 is not particularly limited, and is preferably 0.1 mm or more and 6 mm or less, more preferably 1 mm or more and 4 mm or less. The thickness in this specification indicates the thickness in the direction perpendicular to the axial direction of the image carrier cleaning roller 10 .

The outer diameter of the foamed elastic layer 12 is not particularly limited, and is preferably 6 mm or more and 25 mm or less, more preferably 7 mm or more and 21 mm or less.

The outer peripheral surface of the foamed elastic layer 12 is subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, Itro treatment, flame treatment, etc. for the purpose of improving adhesion with the coating layer 13. It's okay.

The foamed elastic layer 12 is formed by, for example, extruding a silicone rubber composition. Alternatively, the foamed elastic layer 12 may be formed by grinding and polishing the elastic body (cured product of the silicone rubber composition) formed on the shaft body 11 .

The specific gravity of the foamed elastic layer 12 is preferably 0.2 to 0.5 from the viewpoint of securing cell walls that can sufficiently form unevenness of fine particles. The specific gravity of the foamed elastic layer 12 can be adjusted by selecting the type of rubber composition and the type and amount of filler.

(coating layer)
The coating layer 13 contains a base resin and fine particles 15 , and the surface of the coating layer 13 has irregularities formed by the fine particles 15 .
-Base resin-
The base material resin is a material such that the hardness of the surface of the image carrier cleaning roller 10 is 20 or more and 50 or less. Good adhesiveness is preferred, for example, alkyd resins, phenol-modified or silicone-modified alkyd resins, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluorine resins, phenol resins, polyamide resins, urethane resins. Among these, urethane resins and silicone resins are preferred.
The thickness of the coating layer 13 is 5 μm or more and 50 μm or less. When the thickness of the coating layer is within the above range, the cell walls 12a of the foamed elastic layer 12 can be satisfactorily covered, and the fine particles can be arranged substantially uniformly, so that residual fine particles such as silica particles can be scraped off satisfactorily. be able to.
Here, the thickness of the coating layer can be measured by the following method. First, a color 3D laser microscope (VK-9700/VK-8700) manufactured by KEYENCE Co., Ltd. is used to observe the surface of the image carrier cleaning roller and take an image. Next, the observed image is measured using analysis software (shape analysis application VK-H1A1/VK-H2A1, manufactured by KEYENCE).
The covering layer 13 only needs to cover at least the cell walls 12a of the cells 14, and may cover the edges 12b of the cells 14 as well. Moreover, the inside of the cell 14 may be partially covered.

The coating layer 13 can be formed by curing a resin composition containing monomers that are raw materials for the base resin.

-Fine particles-
The average particle size of the fine particles 15 is 4 μm or more and 25 μm or less. The particle size of fine particles is determined as follows. That is, the surface of the conductive roller 1 is observed and an image is taken with a color 3D laser microscope (VK-9700/VK-8700) manufactured by KEYENCE. The presence of resin beads is confirmed from the observation image, and the particle size of the resin beads is measured using analysis software (shape analysis application VK-H1A1/VK-H2A1, particle analysis application VK-H1G1, both manufactured by KEYENCE). .
The glass transition temperature Tg of the fine particles 15 is preferably -50 to 30°C. When the hardness is within the above range, silica particles or the like remaining on the image carrier can be satisfactorily removed by the irregularities formed by the fine particles 15 without damaging the surface of the image carrier.
Examples of the fine particles 15 include urethane, acryl, silicone, polystyrene, ester-based polyimide, polyamide, etc., and preferably have a glass transition temperature Tg of −50 to 30° C., and a glass transition temperature of −50 to −20. °C is more preferred.

The fine particles 15 are preferably contained in a proportion of 3 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the resin composition for forming the coating layer 13, and are contained in a proportion of 15 parts by mass or more and 25 parts by mass or less. It is more preferably contained. When the content of the fine particles 15 is within the above range, the fine particles are exposed on the surface of the coating layer after the resin composition is cured. can be successfully removed.

Since the foamed elastic layer 12 of the image carrier cleaning roller 10 of the present invention is relatively hard, the edge 12b of the cell 14 can effectively remove the developer adsorbed or adhered to the image carrier.
The coating layer 13 of the image carrier cleaning roller 10 covers at least the cell walls 12a of the foamed elastic layer 12, and contains the fine particles 15 so as to be partly exposed on the surface. For this reason, irregularities of the fine particles 15 are formed on the cell walls 12a, while the cells 14 of the foamed elastic layer 12 can maintain the closed cell state.
Therefore, the cleaning roller 10 of the present invention can efficiently remove the developer having a diameter of about several tens of μm from the edge 12b of the cell 14, and can remove fine silica particles and the like from the coating layer 13. Therefore, the cleaning roller 10 can be used for a long time. It exhibits high cleaning performance, that is, high durability.

[Manufacturing Method of Cleaning Roller for Image Carrier]
The cleaning roller 10 of the present invention can be manufactured by a manufacturing method including a step of forming the foamed elastic layer 12 and a step of forming a coating layer containing the fine particles 15 .

Specifically, first, an adhesive or a primer is applied to the outer peripheral surface of the shaft 11 as necessary to form an adhesive layer or a primer layer.

Next, a silicone rubber composition is placed on the outer peripheral surface of this shaft 11 . The method is appropriately selected depending on the silicone rubber composition. Alternatively, a method of injecting the silicone rubber composition into a mold for accommodating the shaft 11 and arranging the silicone rubber composition on the outer peripheral surface of the shaft 11 may be used. Among these methods, the method of integrally dispensing the shaft 11 and the silicone rubber composition using an extruder or the like is preferable in that the work is easy and the work can be performed continuously.

After the silicone rubber composition is placed on the outer peripheral surface of the shaft 11 in this manner, the silicone rubber composition is heated together with the shaft 11 while maintaining this state. Heating of the silicone rubber composition is generally carried out by using a heating furnace such as an infrared heating furnace or a hot air furnace, a heater such as a dryer, or the like, so that the rubber or resin contained in the silicone rubber composition, for example, vinyl group-containing silicone raw rubber, is crosslinked. and under conditions sufficient for the foaming agent to decompose or foam. For example, the addition-curable conductive silicone rubber composition is heated to about 170° C. to 500° C., particularly 200° C. to 400° C. for several minutes to 1 hour, particularly 5 minutes to 30 minutes, If desired, secondary heating may also be performed. The secondary heating stabilizes the physical properties of the foamed elastic layer 12 . In the secondary heating, for example, the cured product of the addition-curable conductive silicone rubber composition crosslinked under the above conditions is heated to a temperature of, for example, 180° C. or higher and 250° C. or lower, preferably 190° C., while it is still extruded. ° C. to 230 ° C. for 1 hour to 24 hours, preferably 3 hours to 10 hours, or using a mold, for example, at 130 ° C. to 200 ° C., preferably 150 ° C. to 180 ° C. , 5 minutes to 24 hours, preferably 10 minutes to 10 hours, by heating again.

The foamed elastic layer 12 formed in this manner is subjected to a grinding process, a polishing process, or the like in order to form cells that are open on the outer peripheral surface. In this finishing step, the size and shape of the foamed elastic layer 12 can be adjusted at the same time in addition to the formation of cells that are open on the outer peripheral surface.

Next, the covering layer 13 is formed. If desired, the outer surface of the foamed elastic layer 12 of the image carrier cleaning roller 10 is coated with a resin composition for the coating layer by, for example, a dipping method, a spraying method, or a roll coating method, and then cured and/or crosslinked. to form a coating layer.

Thus, the image carrier cleaning roller 10 can be manufactured.

[Image forming apparatus]
Next, an embodiment of an image forming apparatus having an image carrier cleaning roller of the present invention will be described with reference to FIG.

As shown in FIG. 3, the image forming apparatus 30 includes a rotatable image carrier 31, such as a photosensitive member, on which an electrostatic latent image is formed, and charging means 32, such as a charging roller, disposed around the image carrier 31. , exposure means 33, developing means 40, transfer means 34 such as a transfer roller and cleaning means 37, and fixing means 35 such as a fixing device for an image forming apparatus on the downstream side of the recording medium 36 in the conveying direction. The image forming apparatus 30 is provided with an image carrier cleaning roller 10 as a cleaning means 37 . The developing means 40 is basically formed in the same manner as the conventional developing means. Specifically, as shown in FIG. It includes a carrier 44 , developer supply means 43 for supplying the developer 42 to the developer carrier 44 , and a developer regulating member 45 for charging the developer 42 . The developer 42 may be a dry developer or a wet developer as long as it is a one-component developer, and may be a non-magnetic developer or a magnetic developer.

The fixing means 35 only needs to be able to fix the developer 42 (electrostatic latent image) transferred to the recording medium 36. For example, the fixing means 35 is a heat roller fixing device having a heat-generating fixing roller, an oven fixing device, or the like. A fixing device, a pressure fixing device having a fixing roller that can be pressed, or the like can be used. These fixing devices may be fixing devices with endless belts. As shown in cross section in FIG. 3, the fixing means 35 includes a fixing roller 53 and an endless belt support disposed near the fixing roller 53 in a housing 50 having an opening 52 for the recording medium 36 to pass through. It includes a roller 54 , an endless belt 55 wound around the fixing roller 53 and the endless belt support roller 54 , and a pressure roller 56 opposed to the fixing roller 53 . It is a pressure heat fixing device in which the pressure roller 56 and the pressure roller 56 are rotatably supported so as to abut or press against each other. The fixing roller 53, the endless belt support roller 54, and the pressure roller 56 each incorporate a heating element (not shown), and the pressure roller 56 is fixed via the endless belt 55 by an urging means (not shown) such as a spring. It is in pressure contact with the roller 53 . As the recording medium 36 passes between the endless belt 55 and the pressure roller 56 pressed against each other, the developer 42 (electrostatic latent image) transferred to the recording medium 36 is fixed by being heated at the same time as being pressed. be able to.

The image forming apparatus 30 according to the invention operates as follows. First, in the image forming apparatus 30 , the charging means 32 uniformly charges the image carrier 31 , and the exposure means 33 forms an electrostatic latent image on the surface of the image carrier 31 . Next, developer 42 is supplied from developing means 40 to image carrier 31 to develop the electrostatic latent image. Next, the developer image is transferred onto the recording medium 36 conveyed between the image carrier 31 and transfer means 34 . This recording medium 36 is conveyed to fixing means 35, and the developer image is fixed on the recording medium 36 as a permanent image. An image can be formed on the recording medium 36 in this manner. On the other hand, after the developer image has been transferred, the image carrier 31 is cleaned by the image carrier cleaning roller 10 arranged on the upstream side of the charging means 32 to remove the developer adhering to or remaining on the outer peripheral surface of the image carrier 31 . At this time, the image carrier cleaning roller 10 as the cleaning means 37 exhibits a high level of cleaning performance for the image carrier 31 as described above. Therefore, the surface of the image carrier 31 that has passed through the pressure contact portion with the image carrier cleaning roller 10 is free from adhesion of developer and foreign matter, and a desired developer image is formed. It is possible to form a high quality image, for example, an image without the afterimage of the previous image.

The image forming apparatus 30 according to the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of achieving the object of the present invention. For example, image forming apparatuses include various image forming apparatuses, and an image forming apparatus capable of forming images at high speed is preferable.

The image forming apparatus 30 of the present embodiment is an electrophotographic image forming apparatus, but in the present invention, the image forming apparatus is not limited to an electrophotographic image forming apparatus, for example, an electrostatic image forming apparatus. may be Further, the image forming apparatus 30 is a monochrome image forming apparatus that stores only a single-color developer 42 in the developing means 40, but in the present invention, the image forming apparatus is not limited to a monochrome image forming apparatus. A four-cycle type color image forming apparatus may be used in which the primary transfer of developer images carried on a bearing member is sequentially repeated onto an intermediate transfer member. As a color image forming apparatus, for example, an image forming apparatus on an image carrier, a tandem type color image forming apparatus in which a plurality of image carriers provided with developing means for each color are arranged in series on an intermediate transfer member or a transfer/transport belt, and the like. is mentioned. The image forming apparatus 30 is, for example, an image forming apparatus such as a copier, facsimile machine, or printer.

In the image forming apparatus 30, a one-component developer is advantageously used as the developer 42, but a two-component developer containing toner and a carrier such as iron or nickel can also be used. .

Hereinafter, the present invention will be described in detail with reference to examples. It should be noted that the present invention is by no means limited to the examples shown below.

[Example 1]
A cleaning roller was produced as follows. Tables 1 and 2 show the main configuration and evaluation results of the resin composition of each layer. The units in Tables 1 and 2 are parts by mass.
(Formation of primer layer)
A shaft (made of SUM22, diameter 10 mm, length 275 mm) subjected to electroless nickel plating was washed with ethanol, and a silicone-based primer (trade name “Primer No. 16” manufactured by Shin-Etsu Chemical Co., Ltd. was applied to its surface. ) was applied. The primer-treated shaft was baked at a temperature of 150° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the outer peripheral surface of the shaft.

(Formation of foamed elastic layer)
The following materials were sufficiently kneaded with a twin roll to prepare an addition reaction type conductive foamed silicone rubber composition (resin composition for foamed elastic layer).
・ Silicone rubber composition “KE-904FU” (manufactured by Shin-Etsu Chemical Co., Ltd.) containing vinyl group-containing silicone raw rubber and silica-based filler 50 parts by mass ・ Vinyl group-containing silicone raw rubber “KE-77VBS” (Shin-Etsu Chemical Co., Ltd. company) 50 parts by mass and 65 parts by mass of the conductivity imparting material "KE-87C40PU" (manufactured by Shin-Etsu Chemical Co., Ltd.) Organic foaming agent "Azobis-isobutyronitrile" (indicated as "AIBN" in Table 1 ) 2.0 parts by mass Addition reaction cross-linking agent “C-153A” (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name) 3.5 parts by mass Appropriate amount of platinum catalyst as addition reaction catalyst Reaction control agent “R- 153A" (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name) 1.0 parts by mass Organic peroxide cross-linking agent "C-3" (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name) 5.0 parts by mass The foamed elastic layer The JIS A hardness of the test piece produced from the resin composition for 2 was 40.

Next, the shaft on which the primer layer is formed and the prepared addition reaction type conductive foamed silicone rubber composition are integrally extruded by an extruder, and an addition reaction type conductive foamed silicone is extruded using an infrared heating furnace (IR furnace). The rubber composition was heated at 250° C. for 10 minutes to foam and crosslink the addition reaction type conductive foamed silicone rubber composition. After that, the addition reaction type conductive foamed silicone rubber composition after foaming and cross-linking is secondarily heated at 200° C. for 7 hours using a gear oven, left at room temperature for 1 hour or more, and then ground using a cylindrical grinder. A foamed elastic layer was formed by grinding to an outer diameter of 11 mm. Thus, the image carrier cleaning roller of Example 1 was manufactured.

(Formation of coating layer)
A coating layer resin composition for forming a coating layer was prepared using the following materials.
・ Isocyanate (MDI type, product name “Coronate-HX”, manufactured by Nippon Polyurethane Industry Co., Ltd.) 18 parts by mass ・ Polyol (product name “ON-F40”, manufactured by Nippon Polyurethane Industry Co., Ltd.) 100 parts by mass (molar ratio (NCO / OH = 0.9))
・As polyurethane beads having a blocked isocyanate group on the surface, “RV-600T” (trade name, manufactured by Negami Kogyo Co., Ltd., isocyanate group content 5% by mass, 10% microcompression strength 12.2 MPa, average particle size 5 μm, average particle size Diameter (average particle diameter/thickness of resin layer) ratio 0.5, glass transition temperature 30° C.) 5 parts by mass (5.0 parts by mass per 100 parts by mass of urethane preparation component)
・ Carbon black (trade name “Toka Black #4500”, manufactured by Tokai Carbon Co., Ltd.)
3 parts by mass Dibutyltin dilaurate (trade name “Di-n-butyltin dilaurate”, manufactured by Showa Chemical Co., Ltd.) 0.03 parts by mass

The coating layer resin composition was applied to the outer peripheral surface of the elastic layer by a spray coating method and heated at 160° C. for 30 minutes to form a coating layer having a layer thickness of 20 μm. A conductive roller was thus manufactured.

[Example 2]
A cleaning roller was produced in the same manner as in Example 1, except that the amount of polyurethane beads added was 10 parts by mass.

[Example 3]
A cleaning roller was produced in the same manner as in Example 1, except that the amount of polyurethane beads added was changed to 20 parts by mass.

[Example 4]
A cleaning roller was produced in the same manner as in Example 1, except that the amount of polyurethane beads added was 40 parts by mass.

[Example 5]
A cleaning roller was produced in the same manner as in Example 1, except that glass beads (average particle size: 5 μm) were used as the particles and the amount added was 20 parts by mass.

[Example 6]
A cleaning roller was produced in the same manner as in Example 1, except that ester-based polyimide beads (average particle size: 5 μm) were used as the particles and the added amount was changed to 20 parts by mass.

[Example 7]
A cleaning roller was produced in the same manner as in Example 1, except that acrylic beads (average particle size: 5 μm) were used as the particles and the amount added was 20 parts by mass.

[Example 8]
A cleaning roller was produced in the same manner as in Example 1, except that a silicone resin was used as the base material of the coating layer, silicone beads (average particle diameter: 5 μm) were used as the particles, and the amount added was 20 parts by mass. .

[Example 9]
A cleaning roller was produced in the same manner as in Example 1, except that polyamide beads (average particle size: 5 μm) were used as the particles and the amount added was 20 parts by mass.

[Comparative Example 1]
A cleaning roller was produced in the same manner as in Example 1, except that polyurethane beads (average particle size: 3 μm) were used as the particles and the added amount was changed to 25 parts by mass.

[Comparative Example 2]
A cleaning roller was produced in the same manner as in Example 1 except that polyurethane beads (average particle size: 30 μm) were used as the particles and the amount added was 10 parts by mass.

(durable printing performance)
The above Examples and Comparative Examples were evaluated for durable printing performance.
0.1 g of Aerosil 200 (silica particles) manufactured by Nippon Aerosil Co., Ltd. and Primer No. 1 manufactured by Shin-Etsu Chemical Co., Ltd. were used. 10 g of 4 was mixed and stirred, and about 0.3 g of the mixture was added dropwise to an aluminum plate of 10×10 cm. A 500 g load was then applied to the cleaning roller and rubbed to remove Aerosil 200 (silica particles). At this time, the Aerosil 200 remaining on the aluminum plate is photographed with a microscope at a magnification of 100, and the area of the area corresponding to the silica particles is obtained when the area of 2 mm ² is subjected to black and white binarization. The following criteria were applied to evaluate durable printing performance.
A: The area of the region corresponding to the silica particles is 30% or less B: The area of the region corresponding to the silica particles is greater than 30% and 60% or less C: The area of the region corresponding to the silica particles is greater than 60% big

(Cell diameter of foamed elastic layer)
The cell diameter of the foamed elastic layer was measured by the method described in the above embodiment.

(Specific gravity of foamed elastic layer)
Specific gravity was measured as follows.
A high-precision electronic hydrometer MDS-300 manufactured by ALFA MIRAGE was used. First, about 0.2 g of the foamed elastic layer was cut out in the air, and then the weight in the air and the weight in water were measured to calculate the specific gravity. The mass of the cut out foamed elastic layer in air was W (g), the mass in water was Ww (g), and the specific gravity (SG) of the foamed elastic layer was calculated from SG = W/(W - Ww).

As shown in Tables 1 and 2, the image carrier cleaning roller having the coating layer of the present invention can provide high-quality image formation over a long period of time.

REFERENCE SIGNS LIST 10 Image carrier cleaning roller 11 Shaft 12 Foamed elastic layer 12a Cell wall 12b Edge of cell 13 Coating layer 14 Cell 15 Fine particles 30 Image forming device 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Recording Body 37 Cleaning Means 40 Developing Means 41 Developer Accommodating Means 42 Developer 43 Developer Supply Means 44 Developer Carrying Member 45 Developer Regulating Member 50 Case 52 Opening 53 Fixing Roller 54 Supporting Roller 55 Endless Belt 56 Pressure Roller

Claims (5)

A cleaning roller for an image carrier comprising a shaft and a foamed elastic layer formed on the outer peripheral surface of the shaft, comprising:
The foamed elastic layer has an average cell diameter of 50 μm or more and 300 μm or less,
The foamed elastic layer has cells open on the surface,
A coating layer containing a base resin and fine particles is provided over at least the cell walls of the cells of the foamed elastic layer to the edge,
The surface of the coating layer has irregularities formed by the fine particles,
The thickness of the coating layer is 5 μm or more and 50 μm or less,
A cleaning roller for an image carrier, wherein the fine particles have an average particle size of 4 μm or more and 25 μm or less. 2. A cleaning roller for an image carrier according to claim 1, wherein said fine particles are made of urethane, acryl, silicone, polystyrene, ester polyimide, or polyamide. 3. The image carrier cleaning roller according to claim 2, wherein the surface of the image carrier cleaning roller has an Asker C hardness of 30 or more and 50 or less. 4. The image carrier cleaning roller according to claim 1, wherein the base resin of the coating layer is a urethane resin or a silicone resin. An image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed; and the image carrier cleaning roller according to any one of claims 1 to 4 arranged to contact the image carrier.

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