JP2009162885A - Electrophotographic roller and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an electrophotographic roller improving productivity and preventing coating defects and the electrophotographic roller manufactured by the method. <P>SOLUTION: In the method of manufacturing the electrophotographic roller 100 including a coating layer 103 on the elastic layer, including: a step of preparing a roller including a conductive support 101 and the elastic layer 102 provided on the outer circumferential surface excluding both end parts of the conductive support; a step of mounting a masking cap on a part where the conductive support of the roller is exposed; a dipping step of dipping the roller into paint from the end part where the masking cap is mounted in a state that longitudinal direction of the roller is vertical; and a step of pulling up the roller from the paint, a dynamic surface tension in lifetime of one second at measurement temperature of 25°C by a maximum bubble pressure method of the paint is 25-50 mN/m, and the pulling up rate when the masking cap is pulled up from the liquid surface is 3.5-7 mm/second or less in the pulling step. The electrophotographic roller manufactured by the method is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic roller, such as a developing roller, a charging roller, a transfer roller, a fixing roller, and a static eliminating roller, which is used in an electrophotographic apparatus such as a printer or a copying machine. The present invention also relates to a method for manufacturing an electrophotographic roller having a step of performing dip coating.

  In electrophotographic apparatuses such as printers and copiers, the following various electrophotographic rollers are used. That is, a charging roller that charges the surface of the photosensitive drum, a developing roller that supplies toner to the surface of the photosensitive drum and develops the electrostatic latent image, a transfer roller that transfers the toner on the photosensitive drum to the recording paper, and a recording paper A fixing roller for fixing the transferred toner;

  In recent years, the need for colorization and high image quality of electrophotography has increased, and there has been a strict demand for eliminating coating defects (such as unevenness and streaks) on the surface of an electrophotographic roller. For example, a contact-type developing roller or a contact-type charging roller with respect to the surface of the photoconductor may cause uneven toner conveyance or non-uniform charging if there are coating defects on the roller surface, which may result in image defects. . Moreover, the improvement of the coating method is also requested | required in order to reduce the coating defect of coating layer formation.

  In general, in an electrophotographic roller used in an electrophotographic apparatus, an elastic layer composed of a solid layer having elasticity or conductivity or a foamed layer thereof is formed on the outer periphery of a columnar or hollow cylindrical conductive support. The And in order to provide surface property or functionality on the outer peripheral surface of this elastic layer, the coating layer which apply | coated various resin coatings is provided. In the electrophotographic roller, this coating layer is the outermost layer or the intermediate layer.

  As a method for producing the coating layer, coating (coating) is used. Specifically, methods such as dip coating, roll coating, and spray coating are used to form a resin coating layer of several μm to several hundred μm. Among them, a dip coating method that is excellent in forming a uniform coating layer is often used. Moreover, in order to improve the coating property of the coating material to the elastic layer surface, or in order to improve adhesiveness with a coating layer, the surface treatment is performed before the elastic layer surface.

  The method for producing an electrophotographic roller by the dip coating method has the following steps. A step of attaching a masking cap to the exposed portion of the conductive support of the roller comprising the conductive support and an elastic layer provided on the outer periphery excluding both ends thereof. A dipping process in which the roller is dipped into the paint in the paint tank from the end where the masking cap is mounted in a state where the longitudinal direction is vertical. A lifting process for lifting the roller from the paint, following the dipping process. In this way, a coating layer is formed on the elastic layer. The masking cap is attached to prevent the paint from adhering to the conductive support.

  Here, at the final stage of pulling up the roller from the paint, that is, when the masking cap and the paint are out of liquid, depending on the paint, the liquid may not be sufficiently cut off, and extra paint may adhere to the masking cap. As a result, excessive paint adhering to the masking cap at the time of pulling up after running out of liquid sometimes dropped on the paint surface of the paint tank. As a result, bubbles may be generated on the surface of the paint in the coating tank, and the bubbles may adhere to the surface of the roller to be dip coated next, causing a coating defect.

As a means for solving this, for example, the lifting is temporarily stopped immediately before the liquid runs out, and after being held for a certain period of time in the stopped state, the conductive substrate is removed from the coating liquid at a speed slower than the previous pulling speed. It has been reported to raise (Patent Document 1). This method prevents the paint from dropping onto the paint surface of the paint tank. However, in this method, even if the dripping of the paint can be controlled, since the pulling is temporarily stopped immediately before the liquid runs out, the manufacturing tact becomes long.
Japanese Patent Laid-Open No. 10-039523

  An object of the present invention is to provide an electrophotographic roller manufacturing method capable of preventing coating defects, and an electrophotographic roller manufactured by the manufacturing method.

According to the present invention, a step of preparing a roller having a conductive support and an elastic layer provided on an outer peripheral surface excluding both ends of the conductive support;
Attaching a masking cap to the exposed portion of the conductive support of the roller;
A dipping step of dipping the roller into the paint from the end where the masking cap is attached, and a pulling up step of lifting the roller from the paint, with the longitudinal direction of the roller being vertical.
In a method for producing an electrophotographic roller having a coating layer on an elastic layer,
The coating surface has a dynamic surface tension of 25 mN / m or more and 50 mN / m or less at a measurement temperature of 25 ° C. by a maximum bubble pressure method and a lifetime of 1 second,
An electrophotographic roller manufacturing method is provided, wherein a pulling speed when the masking cap is pulled from the liquid surface in the pulling step is 3.5 mm / second or more and 7 mm / second or less.

  Also provided is an electrophotographic roller produced by the method for producing an electrophotographic roller.

  According to the present invention, there are provided an electrophotographic roller manufacturing method capable of preventing coating defects, and an electrophotographic roller manufactured by the manufacturing method.

  The main component of the elastic layer is silicone rubber, and has a step of irradiating the surface of the elastic layer with excimer light before the dipping step, the paint contains silicone oil, and the tip of the masking cap has a conical shape It is preferable from the viewpoint of productivity and prevention of coating defects.

  In addition, the coating oil in which the coating oil is prevented by a small amount of addition because the content of the silicone oil in the coating is 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the base resin of the coating Thus, it is possible to provide a highly productive method for producing an electrophotographic roller.

  Further, the present invention provides a method for producing a highly productive electrophotographic roller, wherein the base resin is a urethane resin, and the silicone oil is a polyether-modified silicone oil, whereby a coating with a coating defect is prevented. It became possible to provide.

  In addition, it has become possible to provide a developing roller free from image defects.

  Hereinafter, a method for manufacturing an electrophotographic roller according to the present invention and an electrophotographic roller manufactured by the manufacturing method will be described in detail.

The method for producing an electrophotographic roller according to the present invention comprises the following steps, and produces an electrophotographic roller having a coating layer on an elastic layer.
A step of preparing a roller having a conductive support and an elastic layer provided on the outer peripheral surface excluding both ends of the conductive support.
A process of attaching a masking cap to the conductive support exposed portion of the roller prepared in the above process.
A dipping step of immersing the roller in the coating layer forming coating from the end where the masking cap is mounted in a state where the longitudinal direction of the roller mounted with the masking cap is vertical in the above process.
・ Pulling process to pull up the roller immersed in paint in the above process.

  And the dynamic surface tension (at a measurement temperature of 25 ° C. and a lifetime of 1 second) according to the maximum bubble pressure method of the coating layer forming paint is 25 mN / m or more and 50 mN / m or less.

  In the pulling process, the pulling speed when the masking cap is pulled from the liquid surface is 3.5 mm / second or more and 7 mm / second or less.

  1 and 2 are schematic views showing an example of an electrophotographic roller manufactured according to the present invention. FIG. 1 is a perspective view of an example of an electrophotographic roller manufactured according to the present invention. FIG. 2 is a schematic sectional view of the electrophotographic roller shown in FIG.

  As shown in FIGS. 1 and 2, the electrophotographic roller 100 of the present invention has rubber or plastic on the outer peripheral surface of a cylindrical or hollow cylindrical conductive support 101 (excluding both ends of the conductive support). An elastic layer 102 made of a solid layer or a foam layer thereof is formed. A coating layer 103 formed by applying a coating liquid is laminated on the outer peripheral surface of the elastic layer 102. If necessary, a coating layer having a composition different from that of the coating layer 103 may be provided on another layer or more, for example, outside the coating layer 103.

[Conductive support]
The conductive support 101 functions as an electrode and a support member for the electrophotographic roller. The conductive support 101 is made of, for example, a metal or alloy such as aluminum, copper alloy, or stainless steel, iron that has been plated with chromium, nickel, or the like, or a synthetic resin. The shape is preferably a columnar shape or a cylindrical shape with a hollow center. The outer diameter of the conductive support can be determined as appropriate, but is usually in the range of 4 mm to 20 mm.

[Elastic layer]
The elastic layer 102 has an appropriate hardness and electric power so that, for example, the electrophotographic roller can be pressed against the surface of the photoconductor with an appropriate nip width or nip pressure to uniformly convey the toner to the surface of the photoconductor or can be uniformly charged. It preferably has a resistance value.

  The elastic layer 102 is mainly made of rubber or plastic and is formed of a molded body. Since elasticity is generally required, rubber is used. As the rubber used for the elastic layer 102, various rubbers conventionally used for electrophotographic rollers can be used. Specifically, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR). ), Fluorine rubber, silicone rubber, epichlorohydrin rubber, hydride of NBR, polysulfide rubber, urethane rubber, and the like. Such rubber may be used alone or in combination of two or more. Among these, since it is important that the elastic layer has sufficient elasticity, it is preferable to use silicone rubber or urethane rubber. In particular, it is more preferable to use an addition reaction cross-linkable liquid silicone rubber because it has good processability, high dimensional accuracy stability, and excellent productivity such that no reaction by-product is generated during the curing reaction.

  The addition reaction crosslinkable liquid silicone rubber is a composition containing, for example, organopolysiloxane (A liquid) and organohydrogenpolysiloxane (B liquid), and further containing a catalyst and other additives as appropriate. Organopolysiloxane is a base polymer of silicone rubber, and the molecular weight is not particularly limited, but the weight average molecular weight is preferably 10,000 to 1,000,000, and more preferably 50,000 to 700,000.

  The alkenyl group of the organopolysiloxane is a site that reacts with the active hydrogen of the organohydrogenpolysiloxane to form a crosslinking point. The type is not particularly limited, but is preferably at least one of a vinyl group and an allyl group, more preferably a vinyl group, for reasons such as high reaction with active hydrogen. The organohydrogenpolysiloxane functions as a crosslinking agent for addition reaction, and the number of silicon-bonded hydrogen atoms in one molecule is 2 or more, and 3 or more in order to perform the curing reaction well. The polymer is preferred.

  The weight average molecular weight of the organohydrogenpolysiloxane is not particularly limited, and a preferred weight average molecular weight is about 1000 to 10,000. In order to appropriately perform the curing reaction, a polymer having a relatively low molecular weight and a weight average molecular weight of 1,000 to 5,000 is preferable.

  The addition reaction crosslinking liquid silicone rubber can contain, for example, chloroplatinic acid hexahydrate as a crosslinking catalyst for the organohydrogenpolysiloxane. Moreover, the transition metal compound which shows a catalytic action in hydrosilylation reaction can also be used as a crosslinking catalyst. In this way, an elastic layer mainly composed of silicone rubber is obtained. In addition, that silicone rubber is a main component means that the proportion of silicone rubber is 50% by mass or more when various additives are blended with silicone rubber.

  In the elastic layer, various additives such as a non-conductive filler and a plasticizer may be appropriately blended so that the desired performance can be obtained. Examples of the nonconductive filler include diatomaceous earth, quartz powder, dry silica, wet silica, aluminosilicate, and calcium carbonate. Examples of the plasticizer include polydimethylsiloxane oil, diphenylsilanediol, trimethylsilanol, phthalic acid derivatives, and adipic acid derivatives. Conductive agents having an electron conduction mechanism such as carbon black, graphite and conductive metal oxides and conductive agents having an ion conduction mechanism such as alkali metal salts and quaternary ammonium salts are appropriately added to these silicone rubbers to obtain a desired resistance. It is general to adjust to.

  The layer thickness of the elastic layer 102 is usually preferably in the range of 0.5 mm to 10.0 mm. More preferably, it is 2.0 mm or more and 6.0 mm or less. When it is 0.5 mm or more, it is easy to obtain good elasticity. Even if it is thicker than 10.0 mm, the elasticity is not improved, and from the viewpoint of the material cost of the rubber material, 10.0 mm or less is preferable.

  The elastic layer 102 may be a solid body or a foamed body.

  A roller having an electroconductive support and an elastic layer provided on the outer peripheral surface excluding both ends thereof can be manufactured by a known method. For example, it can be obtained by press-fitting a conductive support into a cylindrical tube extruded to an appropriate layer thickness and then polishing it into a desired shape. Further, there is an injection molding method in which a conductive support is disposed in a cylindrical molding die, and then a material is poured into the die and cured by heating to obtain a cylindrical layer.

  The overall length of the elastic layer 102 is generally 200 mm to 400 mm, corresponding to the paper size of the electrophotographic apparatus. It is preferable that the outer diameter is substantially uniform over the entire length.

  The elastic layer may be polished if necessary. The outer diameter difference (the difference between the maximum value and the minimum value of the outer diameter) of the elastic layer is preferably 30 μm or less. If it is 30 μm or less, it is easy to prevent the occurrence of image defects such as image unevenness due to fluctuations in the nip width and nip force between the photosensitive member and the roller.

  A roller having an elastic layer can be appropriately surface-treated before coating. When applying a coating liquid to the elastic layer which has silicone rubber as a main component, it is desired that the wettability of the surface with respect to a coating liquid is favorable. That is, if the wettability is good, the interface adhesive force between the formed coating layer and the elastic layer is good, and it is easy to prevent the coating layer from peeling off. Therefore, surface treatment can be performed for the purpose of improving the wettability of the elastic layer. In particular, when alcohol or ketone is used as the solvent contained in the paint, it is preferable to make the elastic layer hydrophilic and increase its adhesive strength. There are various methods for making the surface of the elastic layer mainly composed of silicone rubber hydrophilic, but it is preferable to use a method of irradiating the elastic layer with excimer light (center wavelength: 172 nm, half width: 20 nm or less). This is because an excimer lamp that emits excimer light has advantages such as low cost, maintainability, long life, low energy, and a small device. Irradiating excimer light breaks the molecular bonds on the surface of the conductive elastic layer mainly composed of silicone rubber, and hydrophilic groups such as carboxyl groups and hydroxyl groups are bonded to the side chains. can do.

  Excimer light is preferably irradiated while rotating a roller having an elastic layer formed on the outer peripheral surface of the conductive shaft core. This is because excimer light irradiation treatment can be performed uniformly and uniformly by irradiating while rotating. The rotational speed is not particularly limited as long as it is a speed at which the elastic layer is uniformly irradiated with excimer light, but it is usually preferably 10 to 50 rpm. The distance between the excimer lamp and the roller surface having the elastic layer (sometimes referred to as irradiation distance) is preferably 1 mm to 5 mm, and more preferably 2 mm to 3 mm. If the irradiation distance is 1 mm or more, it is easy to control the apparatus, and if it is 5 mm or less, the attenuation of the excimer light in the atmosphere can be suppressed, thereby shortening the excimer light irradiation processing time.

In the present invention, the irradiation treatment with excimer light (center wavelength 172 nm, full width at half maximum of 20 nm or less) is preferably performed in the range of 50 to 300 mJ / cm ² integrated light quantity. The integrated light amount is a product of the irradiation light intensity and the irradiation time, and is determined by measuring the irradiation light intensity and appropriately setting the irradiation time. The irradiation light intensity and the irradiation time are not particularly limited as long as the integrated light amount is within the above range, but usually the irradiation time is preferably 2 to 180 seconds, more preferably 10 to 60 seconds. preferable. The irradiation intensity is preferably a normal 2~6mW / cm ^2, and more preferably, 3~5mW / cm ^2.

When the integrated light quantity is 50 mJ / cm ² or more, the surface of the elastic layer is sufficiently hydrophilic to improve the wettability with respect to the coating liquid, and the adhesion between the elastic layer and the resin layer is increased to prevent the covering layer from peeling off. Easy to do. In addition, by setting the integrated light quantity to 300 mJ / cm ² or less, the elastic layer is made of an elastic body mainly composed of silicone rubber by radicals generated on the surface of the elastic layer, and the resistance of the elastic layer is increased due to high cross-linking. Can be suppressed.

(Coating layer)
The coating material forming the coating layer used in the present invention is preferably a thermosetting resin solution. Examples of the thermoplastic resin include polyester resin, polyepoxy resin, polyurethane resin, silicone resin, phenol resin, and melamine resin. These thermoplastic resins may be used alone or in combination of two or more. Although not particularly limited, it is particularly preferable to use a urethane resin from the viewpoint that self-film reinforcing property, abrasion resistance, and elasticity are easily obtained.

  Various additives are added to these thermoplastic resins as necessary. In order to give conductivity to the coating layer, various conductive agents (conductive carbon, graphite, copper, aluminum, nickel, iron powder, and conductive oxides such as conductive tin oxide and conductive titanium) are used. be able to.

  Furthermore, insulating particles can be used to obtain wear resistance, toner conveyance and uniform charging. The insulating particles are made of a material such as styrene, urethane, polyamide, acrylic, or silicone. Insulating particles are required not to swell or dissolve depending on the solvent used in order to exhibit wear resistance, toner conveyance and uniform charging. The shape of the insulating particles is preferably spherical. These insulating particles preferably have an average particle diameter (volume average diameter) in the range of 3 μm to 30 μm. In particular, it is preferable that the average particle diameter exists in any of the range of 5 μm to 20 μm. When the average particle size of the insulating particles is 3 μm or more, the surface roughness of the electrophotographic roller after the surface layer is formed can be prevented from becoming small, and good toner transportability and charge stabilization can be easily obtained. is there. When the average particle size is 30 μm or less, it is possible to prevent the surface roughness of the electrophotographic roller after the surface layer is formed from being increased, and to prevent an excessive toner conveyance amount and non-uniform charging. Easy.

  In order to make these materials ready to be applied as paints, they can be diluted and dispersed with various organic solvents, water, etc., and adjusted and managed to have a liquid viscosity and liquid temperature suitable for coating. The solvent for preparing the thermoplastic resin solution may be any solvent as long as it can dissolve the resin. For example, lower alcohols such as methanol, ethanol and isopropanol, ketones such as methyl ethyl ketone, cyclohexane and toluene. Xylene and the like are preferably used.

  These materials constituting the coating layer can be dispersed using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a ball mill.

  The coating material suitably used in the method for producing an electrophotographic roller of the present invention has a dynamic surface tension of 25 to 50 mN / m at a measurement temperature of 25 ° C. by a maximum bubble pressure method and a lifetime of 1 second.

  When the dynamic surface tension is less than 25 mN / m, a sufficient coating material is not held on the roller at the time of pulling up from the coating material, and it is difficult to obtain a target coating layer thickness. When the dynamic surface tension exceeds 50 mN / m, even if the final speed of pulling up is reduced, the masking cap and the paint are not sufficiently drained, and excess paint is retained on the masking cap. Drops on the paint surface of the paint tank. This dynamic surface tension can be adjusted to some extent depending on the amount and type of conductive carbon and insulating particles as additives, but can be adjusted as appropriate with silicone oil added to the paint. Accordingly, the paint preferably contains silicone oil.

  The content of the silicone oil blended in the paint is preferably 0.5 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the base resin of the paint. When it is 0.5 part by mass or more, an effect of reducing the dynamic surface tension of the paint can be easily obtained. Moreover, even if it is more than 5.0 parts by mass, the effect of further reducing the dynamic surface tension as a paint cannot be expected due to the dynamic surface tension of the silicone oil itself. Therefore, 5.0 parts by mass or less is preferable from the viewpoint of productivity.

  The silicone oil is preferably a polyether-modified silicone oil. When the polyether-modified silicone oil is used, the compatibility with the urethane resin is good when the base resin of the paint is a urethane resin, and the effect of reducing the dynamic surface tension is easily exhibited.

  It is known that the dynamic surface tension is generally measured by the vibration jet method, the meniscus method, the maximum bubble pressure method, etc., but the value of the dynamic surface tension defined in the present invention is the maximum bubble pressure method (bubble Pressure method).

  In dynamic surface tension measurement by the maximum bubble pressure method, gas is sent from a gas supply source to the probe, and bubbles are generated from the tip of the probe immersed in ink. By changing the gas flow rate at this time, the gas generation rate is changed, and the surface tension is measured by the pressure applied to the bubbles from the paint that changes accordingly. When the bubble radius is equal to the radius of the probe tip, the maximum pressure (maximum bubble pressure) is indicated. The dynamic surface tension σ of the ink at this time is

(In the equation, r is the radius of the probe tip, and ΔP is the difference between the maximum value and the minimum value of the pressure applied to the bubbles.)
It is represented by

  In addition, the lifetime refers to the time from when the bubble leaves the probe after the maximum bubble pressure until the next maximum bubble pressure is reached after a new surface is formed.

  FIG. 3 shows a schematic cross-sectional view of a dip coating apparatus that can be suitably used in the electrophotographic roller manufacturing method of the present invention. An arm 202 attached to the elevating device 201 holds the conductive support 101 and the roller 104 made of the elastic layer 102 provided on the outer peripheral surface excluding both ends thereof. The roller 104 is lowered by driving the lifting device and immersed in the coating tank 203 filled with the paint 106, and then the roller 104 is pulled up by driving the lifting device to form the coating layer 103. The coating material is circulated by the liquid feed pump 204, and the coating tank is filled with a predetermined amount and overflows from the coating tank. The overflowed paint returns from the paint receiving tray 205 to the stirring tank 207 through the return pipe 206. A viscometer 208 is attached to the stirring tank. Based on the signal obtained from the viscometer, the solvent is added from the dilution tank 300 via the diluent controller 209, and the viscosity of the paint is adjusted as appropriate. The coating liquid temperature is appropriately adjusted by adjusting the temperature of the entire dip coating apparatus using a chiller apparatus (not shown). The dip coating device is equipped with devices such as a filter and an air chamber (not shown) as required.

  In forming the coating layer by dip coating, a masking cap 105 is attached to one end of the exposed portion of the conductive support. As described above, the roller 104 is immersed in the paint from the end portion where the masking cap is attached, with the longitudinal direction of the roller being vertical. The masking cap prevents the paint from adhering to the exposed portion of the conductive support. The masking cap includes a covering portion that covers the end portion of the conductive support and a grip portion that grips the end portion of the conductive support.

  Furthermore, the tip of the masking cap has a conical shape (relative to the paint immersion direction). This not only prevents the paint from adhering to the exposed part of the conductive support, but also allows the mask to be immersed in the paint smoothly at the start of immersion, that is, when the masking cap is immersed in the paint. Prevents air bubbles caused by interference with paint. Thereby, it can suppress that a coating defect arises in the formed coating layer.

  The material of the masking cap can be attached to the exposed portion of the conductive support and does not contaminate the paint. Any material that does not swell or dissolve can be used. For example, polyethylene, polypropylene, polyacetal, polyethylene tetrafluoroethylene , Polyfluoroalkoxy resin, polyethylene terephthalate, polyimide, polyamide, polycarbonate, silicone resin, polyurethane, polyester and other thermosetting resins such as phenolic resin and epoxy resin.

  In particular, it is desirable to have a property having high water and oil repellency in addition to the property of not being affected by the coating liquid. This is because the cap once used is easy to rinse and dry when washed for reuse. Examples of these particularly preferable materials include olefin resins such as polyethylene and polypropylene, and fluororesins such as polyethylene tetrafluoroethylene and polyfluoroalkoxy resins.

  Subsequently, a covering layer is formed on the elastic layer by performing a pulling process. The pulling speed (excluding the pulling speed when pulling up the masking cap from the liquid surface) may be determined as appropriate. Further, during the pulling, the pulling speed can be adjusted as appropriate in order to keep the layer thickness of the coating layer constant.

  The pulling speed when pulling up the masking cap from the liquid level is 3.5 mm / second or more and 7 mm / second or less. When the pulling-up speed is higher than 7 mm / sec, when the masking cap and the coating material run out of liquid within the range of the dynamic surface tension described above, the liquid is not sufficiently drained and extra coating material adheres to the masking cap. As a result, excess paint adhering to the masking cap at the time of pulling up after running out of liquid drops on the paint surface of the paint tank. As a result, air bubbles are generated on the surface of the paint in the paint tank, and the air bubbles adhere to the surface of the roller to be subsequently applied by dip coating, thereby generating a coating defect. If it is slower than 3.5 mm / sec, not only will the manufacturing tact become longer and the productivity will be lowered, but it will also be disadvantageous in terms of cost.

  Note that the coating layer may be a single layer or a multilayer structure of two or more layers. Of course, when two or more coating layers are constructed, at least one or all of the layers can be formed according to the method of the present invention.

[Electrophotographic roller]
The electrophotographic roller of the present invention is produced by the production method described above. The electrophotographic roller manufactured by this manufacturing method has high productivity and prevents coating defects.

  The electrophotographic roller of the present invention is not particularly limited as long as it is used for electrophotography, and can be used as, for example, a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. Among these, it is particularly suitable as a charging roller or a developing roller.

  Hereinafter, an example in which the electrophotographic roller of the present invention is mounted on an image forming apparatus as a developing roller will be described.

  The developing roller carries a developer (toner) in a state of being in contact with or pressed against a photosensitive drum as a latent image carrier that carries a latent image. The developing roller has a function of visualizing the latent image as a toner image by applying toner as a developer to the photosensitive drum.

  An example of an electrophotographic process cartridge and an image forming apparatus in which the electrophotographic roller of the present invention is mounted as a developing roller is schematically shown in FIG. This will be described below with reference to FIG.

  This image forming apparatus is provided with a total of four image forming units 10a to 10d for forming yellow, cyan, magenta and black images, respectively, in a tandem manner. The image forming apparatus includes a photosensitive drum 11, a charging device 12 (charging roller in the drawing), an image exposure device (showing a writing beam 13 in the drawing), a developing device 14, a cleaning device 15, and an image transfer device 16 (transfer roller in the drawing). Although these specifications are slightly different in adjustment according to the characteristics of each color toner, the four image forming units 10a to 10d are the same in the basic configuration.

  The developing device 14 includes a developing container 6 that stores the one-component toner 5 and a developing roller 1 that is located in an opening extending in the longitudinal direction in the developing container 6 and is disposed to face the photosensitive drum 11. The electrostatic latent image on the drum 11 is developed and visualized. Further, a toner supply roller 7 for supplying the one-component toner 5 to the developing roller 1 and scraping the one-component toner 5 carried on the developing roller 1 without being used for development from the developing roller 1 is provided. A developing blade 8 that regulates the amount of the one-component toner 5 carried on the developing roller 1 and is frictionally charged is provided.

  The surface of the photosensitive drum 11 is uniformly charged to a predetermined polarity and potential by the charging device 12, and image information is irradiated as a beam 13 from the image exposure device to the surface of the charged photosensitive drum 11, so that an electrostatic latent image is formed. It is formed. Next, one-component toner is supplied from the developing device 14 using the electrophotographic roller of the present invention as the developing roller 1 on the formed electrostatic latent image, and a toner image is formed on the surface of the photosensitive drum 11. As the photosensitive drum 11 rotates, the toner image is transferred to a transfer material 25 such as paper that is supplied in synchronization with the rotation when the toner image comes to a position facing the image transfer device 16.

  In the apparatus shown in FIG. 4, four image forming units 10 a to 10 d are linked in series to form a predetermined color image on one transfer material 25. Therefore, the transfer material 25 is synchronized with the image formation of each image forming unit, that is, the image formation is synchronized with the insertion of the transfer material 25. For this purpose, the transfer roller 17 for transporting the transfer material 25 is sandwiched between the photosensitive drum 11 and the image transfer device 16 so that the drive roller 18, the tension roller 19, and the driven roller 20 of the transfer conveyor belt 17. It is laid around. The transfer material 25 is conveyed to the transfer conveyance belt 17 in a form that is electrostatically adsorbed by the action of the adsorption roller 21. Reference numeral 22 denotes a supply roller for supplying the transfer material 25.

  The transfer material 25 on which the image has been formed is peeled off from the transfer conveyance belt 17 by the action of the peeling device 23 and sent to the fixing device 24, and the toner image is fixed on the transfer material 25 to complete the printing. On the other hand, the photosensitive drum 11 after the transfer of the toner image to the transfer material 25 is further rotated, the surface is cleaned by the cleaning device 15, and is neutralized by a neutralization device (not shown) if necessary. Thereafter, the photosensitive drum 11 is used for the next image formation. In FIG. 4, reference numerals 26 and 27 denote bias power supplies to the image transfer device 16 and the suction roller 21, respectively.

  Here, the description has been made with respect to the apparatus for directly transferring the toner image of each color onto the tandem type transfer material. However, the electrophotographic roller of the present invention may be used as a developing roller in other types of electrophotographic apparatuses. it can. Examples thereof include a monochrome single-color image forming apparatus and an image forming apparatus that forms a color image by temporarily superimposing toner images of respective colors on a transfer roller or a transfer belt and collectively transferring the image onto a transfer member. . Further, an image forming apparatus in which each color developing unit is arranged on a rotor or arranged in parallel with a photosensitive drum may be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these do not limit this invention at all. In the present specification and drawings, φ represents a diameter.

(Measurement of paint dynamic surface tension)
Using a dynamic surface tension meter SITA t60 / 2 manufactured by Eihiro Seiki Co., Ltd., the dynamic surface tension of the paint by the maximum bubble pressure method is measured at a measurement temperature of 25 ° C. and a lifetime of 0.03 to 10 seconds. The measured value of the dynamic surface tension with a lifetime of 1 second was read.

(Image evaluation)
An electrophotographic process cartridge of an electrophotographic image forming apparatus (nominal life: 6000 sheets, A4 size, 5% printing rate, print cartridge: black Cyan, Magenta, Yellow). As the image forming apparatus, an electrophotographic image forming apparatus “HP Color LaserJet 3700” (trade name) manufactured by Hewlett-Packard Company was used.

Next, the electrophotographic process cartridge is incorporated into the image forming apparatus, an image (solid image, halftone image, character image) is output, and whether an image defect has occurred is visually observed and evaluated according to the following criteria. did.
A: Good in all images.
B: Some image defects were confirmed in the solid halftone image, but it is a level that can withstand practical use.
C: Image defects were confirmed in all images.

[Example 1]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
An iron conductive support having an outer diameter of φ6 mm was placed concentrically in a cylindrical mold having an inner diameter of φ12 mm. Addition-reaction cross-linkable liquid silicone rubber (volume resistivity 1 × 10 ⁷ Ω · cm, manufactured by Toray Dow Corning Co., Ltd.) is cast, placed in an oven at 130 ° C. and heat-molded for 20 minutes, and after demolding, 200 ° C. Secondary vulcanization was performed in an oven for 4 hours. Thereby, a roller provided with an elastic layer (hollow cylindrical shape) having a layer thickness of 3 mm and a length of 240 mm on the outer peripheral surface of the conductive support was obtained.

While rotating this roller at 30 rpm, the excimer light is elastically adjusted so that the accumulated light amount becomes 200 mJ / cm ² under the conditions of room temperature, air, irradiation light intensity of 4.2 mW / cm ² and irradiation time of 47.6 seconds. The layer was irradiated. For this purpose, an excimer light reformer (manufactured by Harrison Toshiba Lighting & Technology) was used. At this time, the distance between the excimer lamp and the roller surface having the elastic layer is 2 mm. The center wavelength of excimer light was 172 nm, and the half width was 10 nm. For the measurement of the integrated light amount of excimer light, an ultraviolet integrated light meter (main body type UIT-150, sensor unit type VUV-S172, both manufactured by USHIO INC.) Was used. This ultraviolet integrated light meter has a sensitivity wavelength of 150 to 400 nm.

(Paint adjustment)
The following materials were mixed, methyl ethyl ketone (MEK) was added thereto, and dispersed by a sand mill for 1 hour.
Polyurethane polyol prepolymer “Takelac TE5060” (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass.
-77 parts by mass of isocyanate “Coronate 2520” (trade name, manufactured by Nippon Polyurethane Co., Ltd.).
-Carbon black "Special Black 550" (trade name, manufactured by Degussa Japan Co., Ltd.) 24 parts by mass.
-20 mass parts of crosslinked polybutylmethacrylate "MB30X-12" (trade name, manufactured by Sekisui Plastics Co., Ltd.) as insulating particles.
-2 parts by mass of polyether-modified silicone oil "TFS4445" (trade name, Momentive Performance Materials Japan GK) as silicone oil.

  A coating layer forming coating material having a dynamic surface tension of 40 mN / m was obtained.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. A masking cap having a conical tip as shown in FIG. The material of this masking cap is polyacetal.

  Thereafter, the roller is gripped by the arm attached to the lifting device of the dip coating apparatus having the structure shown in FIG. 3, and the roller is moved from the end where the masking cap is mounted in a state where the longitudinal direction of the roller is vertical. Soaked in paint. In addition, 20 rollers are suspended from the arm.

  Thereafter, the pulling-up was started at a speed of 10 mm / second, and the pulling-up was sequentially performed at a reduced speed. The roller pulling speed when the paint and the masking cap were run out was 5 mm / sec. Note that the number of gears for lifting is 300 at regular intervals.

  Under these conditions, a coating layer (coating layer) was formed on a conductive support and a roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof.

  The above process was repeated 50 times, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  At this time, the surface of the roller for electrophotography (the coating layer formed on the elastic layer) was examined by visual inspection for the 1000 rollers to determine whether there were any coating defects. The coating defects are unevenness and longitudinal stripes that occur in the range from the upper end of the roller to the center, and when these electrophotographic rollers are used in an electrophotographic apparatus, toner conveyance unevenness and unevenness are caused. It causes charging and causes image defects. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Example 2]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
The following materials were mixed, methyl ethyl ketone (MEK) was added thereto, and dispersed by a sand mill for 1 hour.
Polyurethane polyol prepolymer “Takelac TE5060” (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass.
-77 parts by mass of isocyanate “Coronate 2520” (trade name, manufactured by Nippon Polyurethane Co., Ltd.).
Carbon black “Special Black 550” (trade name, manufactured by Degussa Japan Co., Ltd.) 10 parts by mass.
-10 mass parts of crosslinked polybutylmethacrylate "MB30X-12" (trade name, manufactured by Sekisui Plastics Co., Ltd.) as insulating particles.
-Polyether-modified silicone oil “TFS4440” (trade name, Momentive Performance Materials Japan GK) as silicone oil, 8 parts by mass.

  A coating layer forming coating material having a dynamic surface tension of 25 mN / m was obtained.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 1 except that the roller pulling speed when the paint and masking cap were run out was 7 mm / second, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

Example 3
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
The following materials were mixed, methyl ethyl ketone (MEK) was added thereto, and dispersed by a sand mill for 1 hour.
Polyurethane polyol prepolymer “Takelac TE5060” (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass.
-77 parts by mass of isocyanate “Coronate 2520” (trade name, manufactured by Nippon Polyurethane Co., Ltd.).
Carbon black “Special Black 350” (trade name, manufactured by Degussa Japan Co., Ltd.) 40 parts by mass.
-50 mass parts of crosslinked polybutylmethacrylate "MB30X-12" (trade name, manufactured by Sekisui Plastics Co., Ltd.) as insulating particles.
-Polyether-modified silicone oil “TFS4452” (trade name, Momentive Performance Materials Japan GK) 0.8 parts by mass as silicone oil.

  A coating layer forming coating material having a dynamic surface tension of 50 mN / m was obtained.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 2, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

Example 4
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
Similarly to Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
A coating material for coating layer formation was prepared in the same manner as in Example 2.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. A masking cap having a conical tip as shown in FIG. 5 (2) was used. The material was the same as in Example 1.

  Thereafter, dip coating was performed under the same conditions as in Example 1 except that the roller pulling speed when the paint and the masking cap were run out was 3.5 mm / second, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

Example 5
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
In the same manner as in Example 3, a coating layer forming coating material was prepared.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as in Example 4 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 4, and a total of 1,000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 1]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
The following materials were mixed, methyl ethyl ketone (MEK) was added thereto, and dispersed by a sand mill for 1 hour.
Polyurethane polyol prepolymer “Takelac TE5060” (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass.
-77 parts by mass of isocyanate “Coronate 2520” (trade name, manufactured by Nippon Polyurethane Co., Ltd.).
Carbon 50 “Special Black 350” (trade name, manufactured by Degussa Japan Co., Ltd.) 50 parts by mass.
-50 mass parts of crosslinked polybutylmethacrylate "MB30X-12" (trade name, manufactured by Sekisui Plastics Co., Ltd.) as insulating particles.

  A coating layer forming coating material having a dynamic surface tension of 55 mN / m was obtained.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 1 except that the roller pulling speed when the paint and masking cap were run out was 8 mm / sec, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 2]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
The following materials were mixed, methyl ethyl ketone (MEK) was added thereto, and dispersed by a sand mill for 1 hour.
Polyurethane polyol prepolymer “Takelac TE5060” (trade name, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 parts by mass.
-77 parts by mass of isocyanate “Coronate 2520” (trade name, manufactured by Nippon Polyurethane Co., Ltd.).
-Carbon black "Special Black 550" (trade name, manufactured by Degussa Japan Co., Ltd.) 5 parts by mass.
-5 mass parts of crosslinked polybutylmethacrylate "MB30X-12" (trade name, manufactured by Sekisui Plastics Co., Ltd.) as insulating particles.
-Polyether-modified silicone oil “TFS4440” (trade name, Momentive Performance Materials Japan GK) as silicone oil, 15 parts by mass.

  A coating layer forming coating material having a dynamic surface tension of 20 mN / m was obtained.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Comparative Example 1, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 3]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
A paint was prepared in the same manner as in Example 1.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 1 except that the roller pulling speed when the paint and the masking cap were run out was 3 mm / second, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 4]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
A paint was prepared in the same manner as in Example 1.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, dip coating was performed under the same conditions as in Example 1 except that the roller pulling speed when the paint and masking cap were run out was 8 mm / sec, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 5]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
A paint was prepared in the same manner as in Comparative Example 1.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, the roller pulling speed when the paint and the masking cap were run out was 5 mm / second, and dip coating was performed under the same conditions as in Example 1, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

[Comparative Example 6]
(Creation of a roller having an elastic layer on the outer periphery of a conductive support)
As in Example 1, a roller having an elastic layer on the outer periphery of the conductive support was prepared.

(Paint adjustment)
A paint was prepared in the same manner as in Comparative Example 2.

(Formation of coating layer on elastic layer, dip coating)
A masking cap was attached to one end of the exposed portion of the conductive support produced by the above method and the conductive support of the roller provided with an elastic layer on the outer peripheral surface excluding both ends thereof. The same masking cap as that used in Example 1 was used.

  Thereafter, the roller pulling speed when the paint and the masking cap were run out was 5 mm / second, and dip coating was performed under the same conditions as in Example 1, and a total of 1000 rollers were dip coated.

  Thereafter, the coated roller was air-dried and heat-treated at 140 ° C. for 60 minutes to thermally cure the coating layer to obtain an electrophotographic roller.

  As in Example 1, the 1000 rollers were visually inspected. The results are shown in Table 1.

(Image evaluation)
The electrophotographic roller prepared by the above method was incorporated into the electrophotographic process cartridge as a developing roller, and an image was output for evaluation. Table 1 shows the results.

  From the results shown in Table 1, the electrophotographic roller manufacturing method of the present invention has a dynamic surface tension of 25 mN / m or more and 50 mN / m or less, and the pulling speed when the masking cap is pulled up from the liquid surface in the pulling process. When the thickness was 3.5 mm / second or more and 7 mm / second or less, coating defects were prevented. Further, by using this manufacturing method, a high-precision electrophotographic roller (developing roller) free from image defects was obtained. In Comparative Example 3 in which the speed of the paint and the masking cap when the liquid runs out is 3 mm / sec, coating defects are prevented, but the manufacturing tact time becomes long, and the tact times of the preceding and following processes do not match. Not suitable for mass production.

It is a schematic perspective view which shows an example of the roller for electrophotography of this invention. It is a schematic sectional drawing which shows an example of the roller for electrophotography of this invention. It is a schematic sectional drawing which shows an example of the dip coating apparatus which can be used in this invention. 1 is a configuration diagram illustrating an outline of an image forming apparatus. (1) and (2) are schematic sectional views of a roller equipped with a masking cap that can be used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 5 Nonmagnetic one-component toner 6 Developing container 7 Toner supply roller 8 Developing blades 10a to 10d Image forming unit 11 Photosensitive drum 12 Charging device (charging roller)
13 Writing beam from image exposure device 14 Developing device 15 Cleaning device 16 Image transfer device (transfer roller)
17 Transfer Conveying Belt 18 Drive Roller 19 Tension Roller 20 Driven Roller 21 Adsorption Roller 22 Supply Roller 23 Peeling Device 24 Fixing Device 25 Transfer Material 26 Bias Power Supply (for Image Transfer Device (Transfer Roller) 16)
27 Bias power supply (for suction roller 21)
DESCRIPTION OF SYMBOLS 100 Electrophotographic roller 101 Conductive support body 102 Elastic layer 103 Cover layer 104 Roller 105 Masking cap 106 Paint 201 Lifting device 202 Arm 203 Coating tank 204 Liquid feed pump 205 Paint receiving tray 206 Return pipe 207 Stirring tank 208 Viscometer 209 Diluent controller 300 Dilution tank

Claims (6)

Preparing a roller having a conductive support and an elastic layer provided on an outer peripheral surface excluding both ends of the conductive support;
Attaching a masking cap to the exposed portion of the conductive support of the roller;
A dipping step of dipping the roller into the paint from the end where the masking cap is attached, and a pulling up step of lifting the roller from the paint, with the longitudinal direction of the roller being vertical.
In a method for producing an electrophotographic roller having a coating layer on an elastic layer,
The coating surface has a dynamic surface tension of 25 mN / m or more and 50 mN / m or less at a measurement temperature of 25 ° C. by a maximum bubble pressure method and a lifetime of 1 second,
A method for producing an electrophotographic roller, wherein a pulling speed when the masking cap is pulled from the liquid surface in the pulling step is 3.5 mm / second or more and 7 mm / second or less. The main component of the elastic layer is silicone rubber,
Before the dipping step, the step of irradiating the surface of the elastic layer with excimer light,
The paint contains silicone oil;
2. The method for producing an electrophotographic roller according to claim 1, wherein the tip of the masking cap has a conical shape.   The roller for electrophotography according to claim 2, wherein the content of silicone oil in the paint is 0.5 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the base resin of the paint. Manufacturing method.   4. The method for producing an electrophotographic roller according to claim 2, wherein the base resin is a urethane resin, and the silicone oil is a polyether-modified silicone oil.   An electrophotographic roller produced by the method for producing an electrophotographic roller according to claim 1.   The electrophotographic roller according to claim 4, wherein the electrophotographic roller is a developing roller.

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