JP2008142678A - Electrophotographic elastic roller, its manufacturing method, electrophotographic process cartridge, and image-forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic elastic roller which gives excellent shape precision even if a very viscous and thixotropic material is applied, and also provide its manufacturing method, an electrophotograpic process cartridge which is suitable for forming a high-definition image, and an image-forming device. <P>SOLUTION: In the manufacturing method of the electrophotograpic elastic roller, a liquid material is fed from the outer-side inlet part of a circular slit by using a coating head having the circular slit and is discharged from the inner-side outlet part to apply the material to a cylindrical base material, and then the material is hardened. In this case, the yield stress and thixotropic index of the liquid material are 20-600 Pa and 2.0-6.5, respectively, and equations 0.1≤T1/T2<1.0 and 10≤L≤100 are simultaneously satisfied, wherein T1 and T2 (mm) represent the slit widths of the inlet part and outlet part, respectively, and L (mm) represents a distance between the inlet part and the outlet part. An electrophotograpic elastic roller which is manufactured by this method, an electrophotographic process cartridge using the roller as a development roller, and an image-forming device are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylindrical elastic roller used in an electrophotographic apparatus. The present invention also relates to a method for manufacturing an electrophotographic elastic roller in which a liquid rubber material is molded into a roller shape and cured using a coating head having an annular slit. Furthermore, the present invention relates to an electrophotographic process cartridge including an elastic roller and an image forming apparatus.

  Various coating methods such as spray coating, dip coating, blade coating, roll coating, and ring coating with an annular slit are applied as coating methods for coating the outer peripheral surface of a cylindrical substrate to form a coating layer. Is being considered.

  As for the elastic roller used for electrophotographic image formation, a film having a desired function is formed on the surface of the cylindrical body in accordance with various uses of the elastic roller. Particularly in recent years, in order to express such a desired function, a coating film from a uniform thin layer to a thickness of about several millimeters is required, and coating liquids to be applied are diversified. Along with this, some of the coating liquids change from low viscosity to high viscosity. For this reason, it is difficult for conventional coating methods to cover the coating range of such coating liquids.

  As a coating method using a ring having an annular slit in the coating head, a coating method using a hopper type coating device is disclosed (see Patent Document 1). According to this, the relationship between the size of the entrance opening and the exit opening of the annular slit is set to a desired value. As a result, the coating liquid flows smoothly from the inlet opening of the slit to the outlet opening, flows out onto the hopper surface, is applied to the outer peripheral surface of the cylindrical base material, and the coating layer has little film thickness fluctuation in the circumferential direction and the vertical direction. (Also referred to as a coating film) can be formed. Furthermore, even in so-called simultaneous multi-layer coating in which a plurality of coating layers are simultaneously formed on a cylindrical substrate, an excellent coating method is provided that does not cause film thickness fluctuations in the circumferential direction and the vertical direction.

However, although the above conventional method is suitable for forming a thin layer when a material having a low viscosity is used, it has a drawback that air is easily trapped when a material having a high viscosity is used. If irregularities are formed in the thin layer due to the entrainment of air, there may be a problem in the image due to a small white spot on the image. Recently, even fine print unevenness has become a problem on the image as the print image becomes highly detailed. What has not been a problem in an 800 dpi image (the number of dots in 1 inch (25.4 mm)) has been a problem in a 1200 dpi image.
Japanese Patent Laid-Open No. 10-272400

  An object of the present invention is to produce an electrophotographic elastic roller that has good shape accuracy and can reduce air entrainment even when a high viscosity or high thixotropic material is applied using a coating head having an annular slit. Is to provide a method.

  Another object of the present invention is to provide an elastic roller for electrophotography with good shape accuracy and reduced air entrainment.

  Another object of the present invention is to provide an electrophotographic process cartridge and an image forming apparatus suitable for forming a high-definition image.

According to the present invention, the coating head having the upper part and the lower part and having the annular slit formed by the gap between the upper part and the lower part is used, from the outer side entrance portion opened to the outside of the annular slit. A liquid material is supplied, and the liquid material is discharged from an inner side outlet portion opened inside the annular slit, and the coating head is moved relative to the cylindrical base material while moving the coating head relative to the cylindrical base material. A method for producing an elastic roller for electrophotography comprising a step of applying a liquid material and curing the applied liquid material,
The yield stress of the liquid material is 20 Pa or more and 600 Pa or less,
The thixotropic index of the liquid material is 2.0 or more and 6.5 or less,
As the coating head, the gap interval between the outer side inlet portions is T1 (mm), the gap interval between the inner side outlet portions is T2 (mm), the outer side inlet portion and the inner side outlet. When the distance to the part is L (mm),
0.1 ≦ T1 / T2 <1.0 and 10 ≦ L ≦ 100
There is provided a method for producing an electrophotographic elastic roller, characterized in that a coating head is used.

  According to the present invention, there is provided an electrophotographic elastic roller manufactured by the above manufacturing method.

According to the present invention, at least a developer, a developer regulating member, a developer container, and a developing roller are mounted, a thin layer of developer is formed on the surface of the developing roller, and the developing roller is brought into contact with the image forming body. In an electrophotographic process cartridge for forming a visible image on the surface of the image forming body by supplying the developer to the surface of the image forming body,
An electrophotographic process cartridge is provided in which the developing roller is the electrophotographic elastic roller.

According to the present invention, a thin layer of developer is formed on the surface of the developing roller, the developer roller is brought into contact with the image forming body, and the developer is supplied to the surface of the image forming body, whereby the surface of the image forming body is visible. In an image forming apparatus for forming an image,
An image forming apparatus is provided in which the developing roller is the electrophotographic elastic roller.

  According to the present invention, there is provided a method for producing an elastic roller for electrophotography, which has good shape accuracy and can reduce air entrainment even when a high viscosity or high thixotropic material is applied using a coating head having an annular slit. Provided.

  The present invention provides an elastic roller for electrophotography with good shape accuracy and reduced air entrainment.

  According to the present invention, an electrophotographic process cartridge and an image forming apparatus suitable for forming a high-definition image are provided.

  When using a ring-shaped coating head having an annular slit to apply a thick material (for example, 100 μm or more at a time) to a liquid material, it is necessary to consider material characteristics. Basically, a high-viscosity material is used, but there is an appropriate viscosity region in all the shear rate regions involved in the coating process, and it is preferable to consider this in terms of shear rate dependency (thixotropic index). Further, when trying to maintain the shape accuracy at a high level with respect to the coating film thickness, another parameter control for controlling the sagging property of the material is required. Further, when a thixotropic material is used, a pulsating flow is likely to occur when a material in a high viscosity region is flowed, which may involve a large amount of air. Therefore, since the material in the low viscosity region is easy to entrain extremely fine bubble-like air, the shape of the coating head must be considered.

  As a result of diligent research, the inventors of the present invention controlled the yield stress value of the coating material and the shear rate dependence (thixotropic index) of the material viscosity within an appropriate range, and a manufacturing method using a cylindrical coating head It has been found that the above-mentioned problems can be solved when combined with.

  Furthermore, it has been difficult to mold by making the relationship between the cross-sectional areas of the material inlet and the material outlet constituting the annular slit of the coating head within an appropriate range, and considering the shape of the material outlet. It was also found that the above-mentioned problems can be solved even for materials having a yield stress value of 20 Pa or more and 50 Pa or less.

[Material properties]
In the present invention, a non-Newtonian liquid material having a yield stress of 20 Pa or more and 600 Pa or less and a thixotropy index of 2.0 or more and 6.5 or less is formed as a coating material (an elastic layer provided around a cylindrical substrate). Used as a liquid material). Thereby, even when the coating thickness is 100 microns or more, it is possible to obtain a film-formed product with good dimensional accuracy.

  Yield stress (often called the yield point) is the critical stress below which a sample behaves as a solid. The sample is elastically deformed like a spring by the stress, but the deformation disappears when the stress is removed. Below the yield stress, the applied stress and deformation remain proportional. When the yield stress is exceeded, structural breakage of the three-dimensional network structure formed by the agglomerated filler or the like occurs, and the sample starts to flow. Deformation continues indefinitely due to the applied stress, and even if the stress is removed, it does not return to its original shape.

  That is, the gravity applied to the material increases as the thickness of the coating film increases, and the material easily flows in the direction of gravity. In order not to cause a flow, the material should have a sufficient yield stress with respect to gravity. By having a sufficient yield stress with respect to the thickness of the coating film, a molded product having a stable shape and good dimensional accuracy can be obtained.

The thixotropy index represents the amount by which the viscosity changes with respect to the shear rate.
When the thixotropy index is 1, it indicates a Newtonian liquid, and when the thixotropy index is other than 1, it indicates a non-Newtonian liquid. Here, it refers to a liquid having a high viscosity at a low shear rate compared to a viscosity at a high shear rate. The lower the viscosity in the high shear region, the smaller the load on the pump for extruding the material, and the more efficient the productivity. The higher the viscosity in the low shear region, the more difficult the material will drip and the more stable the shape.

  When the yield stress is in the range of 20 Pa or more and 600 Pa or less, the dimensional accuracy with respect to the coating thickness can be maintained and the balance with the smoothness of the coating surface can be achieved in the best condition. A more preferable range of the yield stress is 100 Pa or more and 400 Pa or less.

  When the yield stress of the liquid material for forming the elastic layer exceeds 600 Pa, the leveling effect of the material at the time of coating is too small, and it is difficult to cause streaks or unevenness on the surface after coating. Occurs. If the pressure is less than 20 Pa, the yield stress is too small for the gravity and the shape after the coating is formed cannot be maintained. Therefore, the difference in outer diameter with respect to the coating thickness of the heat-cured elastic roller becomes large. Can not withstand use. A dimensional system that can be suitably used as an electrophotographic elastic roller is a case where a dimensional difference within 3% of the outer diameter of the roller is suppressed, although it depends on the grade and durability of the image forming apparatus. By setting it to 3% or less, the stress applied to the other members is not biased, so that it is possible to excellently prevent the wear and deterioration from being accelerated by the stress. Thereby, it becomes possible to stably supply the charge and the developer, and it is possible to obtain a high-quality image over a long period of time.

  When the thixotropy index range of the liquid material for forming the elastic layer is in the range of 2.0 or more and 6.5 or less, the balance between the flow stability of the material against changes in shear rate and the stable supply of the material must be compatible. Can do. A more preferable range of the thixotropy index is 2.5 or more and 5.0 or less.

  When the thixotropy index exceeds 6.5, the fluidity of the raw material with respect to the shear rate change becomes unstable, and the dimensional stability of the molded coating film is deteriorated. When the yield stress is less than 2.0, when the yield stress is controlled within a predetermined range, the material viscosity is too high at the shear rate in the piping during material transportation, and the apparatus is overloaded with high load. Difficulties arise. When the yield stress of the coating material is 20 Pa or more and 600 Pa or less and the thixotropy index is 2.0 or more and 6.5 or less, it becomes possible to obtain a coating film formed with good dimensional accuracy.

[Coating head shape]
The coating head used in the present invention has an upper part and a lower part, and has an annular slit formed by a gap between the upper part and the lower part. When the interval between the outer side entrance portions of the coating head annular slit is T1 (mm) and the interval between the inner side exit portions of the annular slit is T2 (mm), 0.1 ≦ T1 / T2 <1.0. A more preferable range of T1 / T2 is 0.2 ≦ T1 / T2 <0.8.

  T1 / T2 is a parameter caused by the relationship between the cross-sectional areas of the material inlet and the material outlet. In the case of the annular slit here, the material flows from the outside to the inside of the ring. That is, since the circumference of the outer side (inlet side) of the annular slit is longer than the circumference of the inner side (outlet side), when T1 = T2, the material outlet part sectional area becomes smaller than the inlet part sectional area, The flow rate of the material increases toward the outlet and is accelerated. In the case of a material having a yield stress, it has the property of maintaining its shape as it is discharged, and the material coming out of the discharge port at a high flow rate is the core metal (cylindrical base) or the wall surface near the discharge port It becomes easy to entrain air when it collides with. The idea is to reduce the discharge speed of the material, but simply reducing the discharge speed will cause problems such as the shear rate applied to the material being too small and lacking in shape stability. It is not efficient in terms of productivity, such as slowing down. Therefore, in order to reduce the entrainment of air without lowering the molding tact, it is only necessary to suppress the acceleration of the material toward the outlet, and the value of T1 / T2 is set to a value smaller than the conventional one.

  The value of T2 is preferably in the range of 10% to 200% with respect to the rubber wall thickness (thickness of the elastic layer (after curing)). For example, if the rubber thickness is 2 mm, it is preferably in the range of 0.2 mm to 4 mm. If it is this range, it is favorable with respect to shaping | molding stability and air entrainment.

  When T1 / T2 is in the range of 0.1 ≦ T1 / T2 <1.0, the shear rate gradient from the material inlet portion toward the material outlet portion is not too large and stable in the coating head during material discharge. Material discharge can be performed. Furthermore, since it is suppressed that the material speed discharged from the discharge port becomes too high, it is possible to reduce the entrainment of air.

  In addition, when T1 / T2 is within the above numerical range, the ratio of the cross-sectional area of the material outlet portion is not too large compared to the cross-sectional area of the material inlet portion. It is possible to suppress the lack of properties or problems in shape stability. Furthermore, since the velocity gradient from the material inlet to the material outlet is not too large in the coating head, the occurrence of uneven material discharge in the circumferential direction is effectively suppressed, and Air entrainment due to high speed is also suppressed.

  When the distance between the outer entrance portion and the inner exit portion of the annular slit is L (mm), when L (mm) is in the range of 10 (mm) ≦ L ≦ 100 (mm) The inside of the work head is set to a suitable shear rate, and good dimensional accuracy can be obtained. In particular, when the value of L is within the above numerical range, it is possible to suppress uneven material discharge in the circumferential direction due to the gradient of the material flow rate being too large, and to suppress air entrainment due to the high speed at the slit exit. . Furthermore, it is possible to suppress the instability of discharge due to the change of the material flow direction immediately before the slit exit. A more preferable range of L is 20 (mm) ≦ L ≦ 50 (mm).

[Cylinder body]
As the cylindrical body of the electrophotographic elastic roller, a shaft core body (called a metal core in the case of metal) of the electrophotographic elastic roller can be appropriately selected and used. Further, a conductive shaft core can be used as the cylindrical body. For example, a cylindrical body having a carbon steel alloy surface with 5 μm thick industrial nickel plating can be used as the cylindrical body. Other materials for the conductive shaft core include, for example, alloys such as iron, aluminum, titanium, copper and nickel, alloys of these metals including stainless steel, duralumin, brass and bronze, and carbon black and carbon fibers. It is also possible to use a known material that is rigid and shows conductivity, such as a composite material hardened with plastic. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity besides the column shape. The outer diameter of the shaft core of the electrophotographic elastic roller is usually in the range of 4 mm to 10 mm.

[Elastic layer]
As the liquid material for forming the elastic layer disposed around the cylindrical substrate, a known liquid material used for the electrophotographic elastic roller can be selected and used. However, the yield stress and the thixotropy index are set in the above-described range in an uncured state.

  A conductive elastic layer can be formed on the outer periphery of the conductive shaft core. Various liquid rubbers can be used as a preferable liquid material for forming the conductive elastic layer. Specifically, these rubber materials such as diene rubbers, silicone rubbers, polysulfide rubbers, urethane rubbers, etc. are added with other components to form desired elastic properties when formed into elastic layers. These rubber materials can be used alone or in admixture of two or more. In order to bring the yield stress and thixotropy index into the above-mentioned ranges, various fillers may be added. In particular, a filler with a small particle size having strong cohesion is suitable for extracting thixotropy, and the yield stress can be easily controlled by adjusting the addition amount. The filler having a small particle size preferably has a primary particle size of 100 nm or less, and generally, carbon black, silica particles and the like can be suitably used.

[Surface layer]
In the present invention, a resin or a surface layer is further added to the surface of the conductive elastic base layer formed as described above for the purpose of imparting charging characteristics to the toner (developer), imparting a surface shape, adjusting resistance, and the like. A layer made of an elastomer can also be formed.

[Manufacture of elastic roller for electrophotography]
Next, an embodiment of the method for producing the electrophotographic elastic roller of the present invention will be described with reference to the drawings.

  An example of a coating head having an annular slit of the present invention is shown in FIG.

  FIG. 1 shows an external view of the coating head. This coating head is constituted by a cylindrical metal part, and there is an open portion at the cylindrical central portion, from which material is discharged. Although the material injection port 1001 is provided in the cylindrical side surface portion, this may be a single hole or a plurality of holes, and the hole shape is not particularly limited.

  2, 3, 4 and 5 show sectional views of the coating head.

  FIG. 2 is a sectional view of the coating head constituted by the upper part 301 and the lower part 302 and an annular slit part. A horizontal gap formed by a gap between the two parts is referred to as an annular slit 1002. The material flows from the outer side to the inner side of the annular slit, and the flow rate of the material increases. As will be described later with reference to FIG. 3, the outer inlet portion 1002a and the inner outlet portion 1002b are portions that provide a slit interval T1 and slit portions T2, respectively.

  FIG. 3 shows details of the annular slit portion. The material discharge port 1003 represents a place where the material is discharged from the coating head in a cylindrical shape. The material restricting portion (through hole) 1004 represents a place where the material flow is restricted so that the material discharged from the material discharge port 1003 forms a cylindrical shape. Although the through hole is widened or narrowed from the slit outlet to the material discharge port, it is not particularly limited, but in order to regulate the material flow, it is better that the change in the through hole diameter is small. The outer side entrance part (part which gives the slit interval T1) of the annular slit is at the narrowest position in the annular slit, and when there are continuous positions with the smallest interval, the inner side exit part ( The position is close to the portion giving the slit interval T2. There is no particular limitation on the material coming from any direction immediately before (outstream of) the outer entrance. The inner outlet of the annular slit (the portion providing the slit interval T2) is 0.5 mm outward from the position where the diameter of the material restricting portion (through hole) 1004 is the smallest, and the center line of the material restricting portion (through hole) It is defined as the opening at the position of the line that is parallel to the line. The interval between the annular slits from the outer side entrance (interval T1) to the inner outlet (interval T2) increases by a certain distance, the distance is constant, and the distance increases stepwise. However, there is no particular limitation as long as there is no decrease in the middle. The material restricting portion (through hole) 1004 is provided in the same direction as the core metal moving direction shown in FIG. At this time, the annular slit is provided at a position as shown in FIGS. 3 (c) and 3 (d). The material flow vector X connecting the midpoints (intermediate points of the slit interval) from T1 to T2 may be composed of a composite component of the core metal moving direction vector Y and the slit inward vector Z perpendicular thereto. That's fine. The distance from the outer side entrance part (part giving slit interval T1) to the inner side exit part (part giving slit interval T2) is represented by L.

  FIG. 4 shows another example of the coating head. In this example, the annular slit outlet 1005 of the upper part has an R shape. As long as the relationship of T1 / T2 is satisfied, the C chamfered shape, the staircase shape, and other curved shapes are not limited to the R chamfered shape. The size of the R chamfer is preferably 0.5 (mm) or more and 5.0 (mm) or less. By making it within this range, the discharge of the material becomes more stable. Further, since the angle formed by the direction of the material discharged from the slit outlet with respect to the core metal moving direction can be relaxed, it is possible to further suppress the entrainment of air.

  FIG. 5 shows a state in which a liquid material for forming an elastic layer is applied onto a cored bar 303 that is a cylindrical body using a coating head. The material stopper 304 is fixed to the inner exit end of the annular slit, and the material is discharged in one direction (upward). The clothing layer is formed by the relative movement of the cored bar in the same direction as the material discharge direction inside the material fastening part.

  FIG. 6 shows a schematic cross-sectional view of an example of a ring coater using a ring-type coating head. In the ring coat machine shown in FIG. 6, a column 2 is attached substantially vertically on the gantry 1, and a precision ball screw 3 is attached substantially vertically on the gantry 1 and the column 2. Reference numeral 14 denotes a linear guide, two of which are attached to the column 2 in parallel with the precision ball screw 3. The LM guide 4 connects the linear guide 14 and the precision ball screw 3, and a rotary motion is transmitted from the servo motor 5 through the pulley 6 so that the LM guide 4 can move up and down. A ring-shaped coating head 8 for applying an uncured silicone rubber composition on the outer periphery of the shaft core body is attached to the column 2 on the outer periphery side of the shaft core body 101. Further, a bracket 7 is attached to the LM guide 4, and a shaft core lower holding shaft 9 that holds and fixes the shaft core body 101 is attached to the bracket 7 substantially vertically. Further, the central axis of the upper shaft core holding shaft 10 that holds the shaft core body 101 of the opposite roller is attached to the upper portion of the bracket 7, and the upper shaft core holding shaft 10 faces the lower shaft core holding shaft 9. And it arrange | positions so that it may become substantially concentric, and the shaft core body is hold | maintained. Further, the center axis of the ring-shaped coating head 8 is supported so as to be parallel to the moving direction of the shaft core lower holding shaft 9 and the shaft core upper holding shaft 10. Further, when the shaft core lower holding shaft 9 and the shaft core upper holding shaft 10 are moved up and down, the central axis of the discharge port formed in an annular slit opened inside the coating head 8 and the shaft core lower holding shaft 9 are arranged. The center axis of the holding shaft 10 on the shaft core body is adjusted so as to be substantially concentric. With such a configuration, the central axis of the discharge port formed in the annular slit of the coating head 8 can be made substantially concentric with the central axis of the shaft core body, and the inner peripheral surface of the ring-shaped coating head and the above-mentioned A uniform gap is formed between the outer peripheral surface of the shaft core body 101.

  Further, a supply port 11 for liquid rubber, which is an elastic layer forming material, is connected to a material supply valve 13 via a pipe 12 for conveying the liquid rubber. The material supply valve 13 includes a mixing mixer, a material supply pump, a material fixed amount discharge device, a material tank, and the like in front of the material supply valve 13 so that a fixed amount (a constant amount per unit time) of liquid rubber can be discharged. The liquid rubber is weighed from a material tank by a material dispensing device and mixed by a mixing mixer. Thereafter, the liquid rubber composition mixed by the material supply pump is sent from the material supply valve to the supply port via the pipe 12.

  Further, the liquid rubber composition passes through an annular slit in the ring type coating head and is discharged from a material discharge port (nozzle) of the ring type coating head. In order to make the thickness of the liquid rubber composition constant, the discharge amount from the ring-shaped coating head nozzle and the supply amount from the material supply pump are made constant, and the shaft core holding shaft is set in the vertical direction (the shaft core body Move up and down in the direction of the central axis). As a result, the shaft core moves in the axial direction relative to the coating head 8, and a cylindrical (roll-shaped) uncured layer 102a made of a liquid rubber composition is formed on the outer periphery of the shaft core. Is done. At this time, the clearance between the shaft core and the ring-type coating head nozzle is preferably set to a clearance equal to or larger than the desired elastic layer (after curing) because the liquid rubber composition shrinks upon curing. In particular, the clearance is preferably about 1.1 times the layer thickness of the elastic layer (after curing).

  In the next step, the layer of the uncured liquid rubber composition can be cured by a heat treatment such as infrared heating to obtain an elastic roller. The surface of the uncured liquid rubber composition has adhesiveness. For this reason, the heat treatment is preferably non-contact, simple apparatus, and infrared heating that can uniformly heat the uncured liquid rubber composition layer in the longitudinal direction. At this time, the infrared heating apparatus is fixed, and the shaft core body provided with the cylindrical (roll-shaped) uncured material layer made of the liquid rubber composition is rotated in the circumferential direction, so that the heat treatment is uniformly performed in the circumferential direction. Is called. The heat treatment temperature on the surface of the elastic layer material of the liquid rubber composition is preferably 100 to 250 ° C. at which the curing reaction starts, although it depends on the liquid rubber composition to be used.

  Here, for the purpose of stabilizing physical properties of the elastic layer after curing, removing reaction residues and unreacted low molecular components in the elastic layer, secondary curing is performed by further heat-treating the elastic layer after infrared heating. You may let them.

  A surface layer can be further provided on the outer peripheral side of the elastic layer formed as described above from the viewpoint of wear resistance, toner chargeability, and releasability. Examples of the material for forming the surface layer include various polyamides, fluororesins, hydrogenated styrene-butylene resins, urethane resins, silicone resins, polyester resins, phenol resins, imide resins, olefin resins, and the like. These materials may be used alone or in combination of two or more. Various additives are added to these materials as necessary.

  These materials constituting the surface 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 obtained dispersion for forming the surface layer can be applied to the surface of the elastic layer by a spray coating method, a dipping method or the like. The thickness of the surface layer is preferably 5 μm to 50 μm. 5 μm or more is preferable from the viewpoint of preventing the low molecular weight component from seeping out and contaminating the photosensitive drum, and 50 μm or less is preferable from the viewpoint of preventing the roller from becoming hard and causing fusion. More preferably, it is 10 micrometers-30 micrometers.

  Asperities on the roller surface can be formed by dispersing fine particles having a mass average particle diameter of 1 μm to 20 μm in the surface layer formed as described above. Examples of the fine particles used for such purpose include plastic pigments such as polymethyl methyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles. In particular, polymethyl methyl methacrylate fine particles and silicone rubber fine particles are preferable. These fine particles are preferably added in a range of about 5 to 40% by mass of the surface layer (based on the total mass of the surface layer constituent components excluding the fine particles). .

  An example of the electrophotographic elastic roller of the present invention is shown in FIG.

  The elastic roller of the present invention has an elastic layer 102 around a shaft core body 101 and a surface layer 103 disposed on the outer periphery thereof. The surface layer does not have to be a single layer and may be a multilayer.

[Electrophotographic process cartridge and image forming apparatus]
The elastic roller for electrophotography of the present invention can be used as a developing roller. The developing roller bears the developer while being in contact with or pressed against a photosensitive drum as a latent image carrier (image forming member) that carries a latent image. The developing roller has a function of visualizing the latent image as a developer image by applying toner (developer) as a developer to the photosensitive drum. Furthermore, the electrophotographic process cartridge and the image forming apparatus of the present invention include this developing roller.

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

  The image forming apparatus includes four image forming units 212a to 212d that form yellow, cyan, magenta, and black images, respectively, and is provided in a tandem manner. Each image forming unit includes a photosensitive member (photosensitive drum or image forming member) 205, a charging device 206, an image exposure device (writing beam 207 in the drawing), a developing device 208, a cleaning device 209, and an image transfer device 210 (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 212a to 212d are the same in the basic configuration. The photosensitive member 205, the charging device 206, the developing device, and the cleaning device 209 are integrated to form a process cartridge.

  The developing device 208 includes a developing container (developer container) 214 that contains a one-component toner 213, a developing roller 201 that is positioned in an opening extending in the longitudinal direction in the developing container, and that is opposed to the photoconductor 205. The electrostatic latent image on the photoconductor 205 is developed and visualized. Further, a toner supply roller 215 is provided that supplies the one-component toner 213 to the developing roller 201 and scrapes the one-component toner 213 carried on the developing roller 201 without being used for development from the developing roller 201. A developing blade (developer regulating member) 216 that regulates the amount of the one-component toner 213 carried on the developing roller 201 and frictionally charges is provided. A thin layer of one-component toner is formed on the surface of the developing roller by the toner supply roller and the developing blade.

  The surface of the photoconductor 205 is uniformly charged to a predetermined polarity and potential by the charging device 206, and image information is irradiated as a beam 207 from the image exposure device onto the surface layer of the charged photoconductor 205, thereby causing an electrostatic latent image. Is formed. Next, one-component toner is supplied from the developing device 208 having the developing roller 201 onto the formed electrostatic latent image, and a toner image is formed on the surface of the photoreceptor 205. The toner image is transferred to a transfer material (paper) 211 such as paper supplied in synchronization with the rotation when the toner image reaches a portion facing the image transfer device 210 as the photosensitive member 205 rotates.

  In the drawing, four image forming units 212 a to 212 d are formed in a series of manner so that a predetermined color image is superimposed on one transfer material 211. Therefore, the transfer material 211 is synchronized with the image formation of each image forming unit. That is, the image formability is synchronized with the insertion of the transfer material 211. For this purpose, the drive roller 218, the tension roller 219, and the driven roller 220 of the transfer conveyance belt 217 are arranged so that the transfer conveyance belt 217 for transporting the transfer member 211 is sandwiched between the photosensitive member 205 and the image transfer device 210. It is laid around. The transfer material 211 is conveyed in a form that is electrostatically adsorbed to the transfer conveyance belt 217 by the action of the adsorption roller 221. Reference numeral 222 denotes a supply roller for supplying the transfer material 211.

  The transfer material 211 on which the image has been formed is peeled off from the transfer conveying belt 217 by the action of the peeling device 223 and sent to the fixing device 224, and the toner image is fixed on the transfer material 212, and printing is completed. On the other hand, the photosensitive member 205 after the transfer of the toner image to the transfer material 212 is further rotated, the surface of the photosensitive member 205 is cleaned by the cleaning device 209, and is discharged by a discharging device (not shown) as necessary. Thereafter, the photoreceptor 205 is used for the next image formation. In the figure, reference numerals 225 and 226 denote bias power sources for the image transfer device 210 and the suction roller 221, respectively.

  Here, the description has been given of the apparatus that directly transfers the toner images of the respective colors onto the tandem transfer material, but the present invention is not limited thereto. In addition to the apparatus to which the electrophotographic elastic roller of the present invention can be applied, a monochrome image forming apparatus for black and white, a toner image of each color is once superimposed on a transfer roller or a transfer belt, and a color image is collectively transferred to formation. And an image forming layer. In addition, an image forming apparatus in which each color developing unit is arranged on a rotor or arranged in parallel with a photosensitive member may be used. Further, instead of the process cartridge, a photoreceptor, a charging device, a developing device, or the like may be directly incorporated in the image forming apparatus.

<Molecular weight measurement method>
A method for measuring the molecular weight by GPC is described below.

The molecular weight (number average molecular weight Mn, weight average molecular weight Mw, Z average molecular weight Mz) of the chromatogram by gel permeation chromatography (GPC) is measured under the following conditions. The column was stabilized in a 40 ° C. heat chamber, and tetrahydrofuran (THF) as a solvent was passed through the column at this temperature at a flow rate of 1 ml / min, and the sample concentration was adjusted to 0.05 to 0.6% by mass. About 50 to 200 μl of THF sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number (retention time). Examples of standard polystyrene samples for preparing a calibration curve include those manufactured by Tosoh Corporation or Pressure Chemical Co. The molecular weights manufactured are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8 ^{.6 × 10 5, 2 × 10} 6, used as a 4.48 × 10 ^6, it is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 (all trade names) manufactured by Showa Denko K.K. be able to. In addition, a combination of μ-styragels 500, 103, 104, and 105 (all trade names) manufactured by Waters can be given.

<Yield stress measurement method>
A method for measuring the yield stress of a liquid rubber material which is a liquid material for forming an elastic layer using a viscoelasticity measuring apparatus will be described below.

  As a viscoelasticity measuring apparatus, Rheo Stress 600 (trade name) manufactured by Haake was used.

  About 1 g of material was sampled and placed on the sample stage, the cone plate was gradually brought closer, and a measurement gap was set at a position of about 50 μm from the sample stage (a cone plate with a diameter of 35 mm and an inclination angle of 1 ° was used. ) At that time, the material extruded around was removed cleanly so as not to affect the measurement.

  The temperature of the platen was set so that the material temperature was 25 ° C., and the sample was left for 10 minutes after setting the sample, and then the measurement was started.

  The stress applied to the sample is varied from 180 Pa to 50000 Pa (frequency is 1 Hz) over 180 seconds, and changes in G ′ storage elastic modulus, G ″ loss elastic modulus, and phase difference tan δ at that time Measurement was performed at 32 points, and G ′ initially had a constant value in the linear viscoelastic region, and thereafter, the stress value at the point where G ′ storage elastic modulus and G ″ loss elastic modulus crossed each other was read and used as yield stress.

<Thixotropic index: TI value>
A method for obtaining a thixotropy index of a liquid rubber material, which is a liquid material for forming an elastic layer, using a rotational viscometer will be described below. RE550U (trade name) manufactured by Toki Sangyo Co., Ltd. was used as the rotational viscometer.

About 0.25 mL of the sample was set on the sample stage, and pretreatment was performed at 10 rpm for 30 sec using a cone rotor of R9.7 and an inclination angle of 3 °. Immediately after the end of the pretreatment, the shear rate (s ^-1 ) was measured under the conditions of 0.2 for 100 sec, 0.4 for 50 sec, 1 for 30 sec, 2 for 30 sec, 4 for 30 sec, and 10 for 30 sec. At this time, the thixotropic index was obtained by dividing the viscosity measured at the shear rate 1 by the viscosity measured at the shear rate 10.

(Elastic layer rubber material)
Liquid silicone rubber was used as the liquid material for forming the elastic layer. The liquid silicone rubber was used as a base material by blending organopolysiloxane with silica powder, quartz powder, carbon black or the like as a filler. This base material was further mixed with a trace amount of a platinum compound as a curing catalyst to make a mixture A. Separately from this, a mixture B was prepared by blending organohydrogenpolysiloxane with the base material. Mixtures A and B were each set in a raw material tank attached to the ring coater, and sent to a static mixer using a pressure feed pump to mix the mixture A and the mixture B at a ratio of 1: 1 (mass basis).

  For the yield stress and thixotropy index of the liquid material for forming an elastic layer, measured values obtained by mixing the mixture A and the mixture B at a ratio of 1: 1 were used as the measured values of the material.

[Example 1]
(Preparation of silicone rubber composition)
Molecular chain terminal vinyl group-capped dimethylpolysiloxane (molecular weight Mw = 100,000): 80% by mass.
Carbon black (trade name: Denka Black powder form, manufactured by Denki Kagaku Kogyo): 7% by mass.
Silica (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL50): 13% by mass.

  The above blend was mixed and defoamed for 30 minutes using a planetary mixer to obtain a silicone rubber base material. Furthermore, 0.02 parts by mass of an isopropyl alcohol solution of chloroplatinic acid (platinum content: 3% by mass) was added to and mixed with 100 parts by mass of the base material to obtain a mixture A. Separately, 1.5 parts by mass of an organohydrogenpolysiloxane having a viscosity of 10 cps (0.01 Pa · s) (SiH content: 1% by mass) was added to 100 parts by mass of the base material and mixed to obtain a mixture B. Mixture A and Mixture B were separately set in a raw material tank, and sent to a static mixer using a pressure feed pump, and Mixture A and Mixture B were mixed at a ratio of 1: 1 (mass basis). Thus, a silicone rubber composition having a yield stress of 210 Pa and a thixotropy index (hereinafter referred to as TI value) of 4.82 was obtained as a liquid material for forming an elastic layer.

(Creation of conductive roller)
A ring coating head having a cylindrical structure as shown in FIG. 2 was used. T1 / T2 of this ring coating head was 0.33, and L was 30 mm. The inner diameter was 12.0 mm. As the coating machine, a ring coater having the structure shown in FIG. 6 was used.

  An iron core body having an outer diameter of 6 mm is vertically held by the shaft core body holding shafts (the shaft core body holding shaft 10 and the shaft core body lower holding shaft 9) of the ring coating machine, and the shaft core body 101 and the ring-shaped coating are applied. The clearance of the working head 8 from the nozzle was set to 3.0 mm.

  The shaft core body was moved by raising the shaft core body holding shaft vertically (10 mm / sec). Accordingly, the silicone rubber composition is discharged at 840 ml / sec to form a silicone rubber composition layer in a cylindrical shape (roll shape) made of the silicone rubber composition on the outer periphery of the shaft core body. A roller having a molded product layer (hereinafter, uncured roller) was prepared.

  This uncured roller is rotated at 60 rpm around the shaft core body, and infrared light (output 1000 W) is applied to the surface of the uncured molded product layer using an infrared heating lamp “HYL25” (trade name) manufactured by Hibeck Co., Ltd. Irradiation was performed for 4 minutes to cure the molded product layer. Note that the distance between the surface of the molded product layer and the lamp during infrared irradiation was 60 mm, and the temperature of the molded product layer surface was 200 ° C. Thereafter, secondary curing at 200 ° C. for 4 hours in an electric furnace is performed for the purpose of stabilizing the physical properties of the cured silicone rubber elastic layer and removing reaction residues and unreacted low molecular components in the elastic layer of silicone rubber. And a silicone rubber layer was formed on the cored bar (shaft core body).

(Production roller development)
100 parts by mass of polyurethane polyol prepolymer “Takelac TE5060” (trade name) manufactured by Mitsui Takeda Chemical Co., Ltd., 77 parts by mass of isocyanate “Coronate 2521” (trade name) manufactured by Nippon Polyurethane Co., Ltd. MEK (methyl ethyl ketone) was added to 24 parts by mass of “MA100” (trade name), and dispersed with a sand mill for 1 hour. After dispersion, MEK was further added to adjust the film thickness after coating and drying to 20 μm in the range of 20% by mass to 30% by mass to obtain a coating material for the surface layer.

  A metal core having a silicone rubber layer formed therein was immersed in the coating material, and the surface layer coating material was applied to the surface of the coating material, followed by natural drying. Next, heat treatment was performed at 140 ° C. for 60 minutes to cure the paint film, and an elastic roller having a surface layer formed thereon was obtained. This elastic roller was evaluated as a developing roller. Although the details of the evaluation will be described later, when an image was output and evaluated, a good image was obtained.

[Example 2]
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.11 and L = 30 mm.

Example 3
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.91 and L = 30 mm.

Example 4
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.33 and L = 10 mm.

Example 5
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.33 and L = 100 mm.

Example 6
Molecular chain terminal vinyl group-capped dimethylpolysiloxane (molecular weight Mw = 100,000): 80% by mass.
Carbon black (product name: Denka Black powder form, manufactured by Denki Kagaku Kogyo): 5% by mass.
Quartz (manufactured by Pennsylvania Glass Sand, trade name: Min-Usil): 15% by mass.

  The above blend was mixed and degassed for 30 minutes using a planetary mixer, and a silicone rubber base material was obtained in the same manner as in Example 1.

  An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that the above material was used as the base material. The physical properties of the elastic layer forming liquid material were a yield stress of 20 [Pa] and a TI value of 2.0.

Example 7
Molecular chain weight terminal vinyl group-blocked dimethylpolysiloxane (molecular weight Mw = 100,000): 60% by mass.
Molecular chain weight terminal vinyl group-blocked dimethylpolysiloxane (molecular weight Mw = 500,000): 30% by mass.
Carbon black (product name: MA11 manufactured by Mitsubishi Chemical): 5% by mass.
Silica (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL 380): 5% by mass.

  The above blend was mixed and degassed for 30 minutes using a planetary mixer, and a silicone rubber base material was obtained in the same manner as in Example 1.

  An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that the above material was used as the base material. The physical properties of the elastic layer forming liquid material were a yield stress of 600 Pa and a TI value of 6.5.

Example 8
Elastic roller in the same manner as in Example 1 except that the ring coating head T1 / T2 is 0.17, L = 30 mm, and the shape of the annular slit outlet end of the upper part is an R2 chamfered shape (2 mm R processing). Was prepared and evaluated as a developing roller.

Example 9
Example 1 except that the ring coating head T1 / T2 is 0.33, L = 30 mm, and the shape of the annular slit outlet end of the upper part is an R0.5 chamfered shape (0.5 mm R processing). An elastic roller was prepared and evaluated as a developing roller.

Example 10
The elastic roller is the same as in Example 1 except that the ring coating head T1 / T2 is 0.16, L = 30 mm, and the shape of the annular slit outlet end of the upper part is an R5 chamfered shape (R processing of 5 mm). Was prepared and evaluated as a developing roller.

Example 11
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.20 and L = 20 mm.

Example 12
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.8 and L = 50 mm.

[Comparative Example 1]
Molecular chain terminal vinyl group-capped dimethylpolysiloxane (molecular weight Mw = 100,000): 75% by mass.
Carbon black (product name: Denka Black powder form, manufactured by Denki Kagaku Kogyo): 5% by mass.
Silica (manufactured by Nippon Silica Industry, trade name: Nipsil SS50): 7% by mass.
Quartz (manufactured by Pennsylvania Glass Sand, trade name: Min-Usil): 13% by mass.

  The above blend was mixed and degassed for 30 minutes using a planetary mixer, and a silicone rubber base material was obtained in the same manner as in Example 1.

  An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that the above material was used as the base material. The physical properties of the elastic layer forming liquid material were a yield stress of 15 [Pa] and a TI value of 1.88.

[Comparative Example 2]
Molecular chain weight terminal vinyl group-blocked dimethylpolysiloxane (molecular weight Mw = 500,000): 60% by mass.
Carbon black (trade name: Ketjen EC, manufactured by Ketjen International): 20% by mass.
Silica (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL 380): 20% by mass.

  The above blend was mixed and degassed for 30 minutes using a planetary mixer, and a silicone rubber base material was obtained in the same manner as in Example 1.

  An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that the above material was used as the base material. The physical properties of the liquid material for forming the elastic layer were a yield stress of 800 [Pa] and a TI value of 7.21.

[Comparative Example 3]
Elastic roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head is 0.08, L = 30 mm, and the shape of the annular slit exit end of the upper part is an R2 chamfered shape (R processing of 2 mm). Was prepared and evaluated as a developing roller.

[Comparative Example 4]
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 1.0 and L = 30 mm.

[Comparative Example 5]
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.33 and L = 5 mm.

[Comparative Example 6]
An elastic roller was prepared and evaluated as a developing roller in the same manner as in Example 1 except that T1 / T2 of the ring coating head was 0.33 and L = 110 mm.

[Evaluation and results]
<Air entrainment>
The elastic roller obtained in each example and comparative example was incorporated in the developing cartridge as a developing roller, and an evaluation image was output using Color Laser Jet 3700 (trade name) (600 dpi) manufactured by HP, and used for image evaluation. Furthermore, the image for evaluation was output using what was modified to 1200 dpi, and used for image evaluation. Evaluation was based on the following criteria.
A: No irregularities due to air entrainment at all and no problem on the 1200 dpi image.
B: Although there is an extremely minute uneven shape due to air entrainment, it does not cause a problem on a 1200 dpi image.
C: There is a concavo-convex shape due to air entrainment, and there is no problem with a 600 dpi image, but there is a problem with an image at 1200 dpi.

  After the image evaluation, the part of the developing roller that was problematic on the image was cut with a sharp blade, and the cross-section was observed with an optical microscope. As a result, it was determined that a rubber having a void or an uneven shape was caused by air entrainment.

<Shape measurement>
The rollers obtained in each Example and Comparative Example were rotated with the shaft core as the rotation axis, and a non-contact laser length measuring device (manufactured by Keyence Corporation, trade name: LS-5000) was installed perpendicular to the rotation axis. The distance (elastic layer thickness) to the outer peripheral surface of the elastic roller was measured using the end face of the shaft core as a reference. Measurement points were measured at 5 ° in the roller axis direction (2 locations at 10 mm from both ends of the elastic layer, 1 location at the center of the elastic layer, 2 locations at the 10 mm position from both ends of the elastic layer and the midpoint of the rubber) at 1 ° pitch. 360 data were acquired per axial location. Furthermore, the roundness was analyzed. Evaluation was based on the following criteria.
A: Roundness of 10 μm or less.
B: When the roundness is larger than 10 μm and not larger than 30 μm, it does not cause a problem on the image.
C: When the roundness is 30 μm or more, the image has a problem.

  The evaluation on the image was performed in the same manner as the image evaluation of air entrainment. It was visually confirmed that white or dark horizontal stripes entered on the image in the direction perpendicular to the image printing direction, and judged to be a problem on the image.

  As described above, according to the present invention, the relationship between the size of the material entrance opening and the exit opening of the coating head having an annular slit is controlled, and the physical properties of the coating material are controlled. Thereby, even when a high viscosity or high thixotropic material is applied, the shape accuracy is good and air entrainment can be reduced.

It is a schematic diagram which shows the example of the ring coating head which can be used in this invention. It is a schematic diagram which shows the example of the ring coating head which can be used in this invention. (A) is sectional drawing of a ring coating head, (b) is a cross-sectional perspective view of a ring coating head. It is a schematic diagram of a ring coating head for demonstrating T1, T2 and L which concern on the structure of a ring coating head. (A) is sectional drawing of a head, (b) is the elements on larger scale, (c) And (d) is a figure for demonstrating the flow direction of a liquid material. It is typical sectional drawing of the ring coating head for demonstrating the R chamfering shape of the slit exit end of upper part. It is typical sectional drawing of a ring coating head for demonstrating the coating method by a ring coating head. It is a schematic diagram which shows the example of the coating machine using a ring coating head. It is a schematic diagram which shows the example of the elastic roller for electrophotography of this invention. FIG. 2 is a schematic diagram for explaining an example of a process cartridge and an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Column 3 Ball screw 4 LM guide 5 Servo motor 6 Pulley 7 Bracket 8 Ring-shaped coating head 9 Shaft core lower holding shaft 10 Shaft core upper holding shaft 11 Supply port 12 Piping 13 Material supply valve 14 Linear guide DESCRIPTION OF SYMBOLS 101 Shaft body 102 Elastic layer 103 Surface layer 201 Developing roller 205 Photoconductor 206 Charging device 207 Image exposure device 208 Developing device 209 Cleaning device 210 Image transfer device 211 Transfer material 212 Image forming unit 213 Toner 214 Developing container 215 Toner supply roller 216 Developing blade 217 Transfer conveyor belt 218 Drive roller 219 Tension roller 220 Driven roller 221 Adsorption roller 222 Transfer material supply roller 223 Separating device 224 Fixing device 225, 226 Bias power supply 301 Upper part 301 Lower part 303 Core metal 304 Charge retaining parts 1001 material inlet 1002 outward inlet 1002b inner side outlet 1003 material discharge port 1004 material regulating portion 1005 annular slit outlet end of R chamfered upper part of the slit of the annular slit 1002a slit

Claims (6)

Using a coating head having an upper part and a lower part and having an annular slit formed by a gap between the upper part and the lower part, a liquid material is supplied from an outer side entrance that opens outside the annular slit. Then, the liquid material is discharged from the inner side outlet that opens inside the annular slit, and the liquid material is applied to the cylindrical base material while moving the coating head relative to the cylindrical base material. A method for producing an electrophotographic elastic roller having a step of curing a coated liquid material,
The yield stress of the liquid material is 20 Pa or more and 600 Pa or less,
The thixotropic index of the liquid material is 2.0 or more and 6.5 or less,
As the coating head, the gap interval between the outer side inlet portions is T1 (mm), the gap interval between the inner side outlet portions is T2 (mm), the outer side inlet portion and the inner side outlet. When the distance to the part is L (mm),
0.1 ≦ T1 / T2 <1.0 and 10 ≦ L ≦ 100
A method for producing an elastic roller for electrophotography, comprising using a coating head.   The method for producing an electrophotographic elastic roller according to claim 1, wherein the shape of the annular slit outlet end of the upper part is an R chamfered shape of 0.5 mm to 5.0 mm. Said T1, T2 and L are
0.2 ≦ T1 / T2 ≦ 0.8 and 20 ≦ L ≦ 50
The manufacturing method of the elastic roller for electrophotography of Claim 1 or 2 satisfy | filling these.   An electrophotographic elastic roller produced by the production method according to any one of claims 1 to 3. At least a developer, a developer regulating member, a developer container, and a developing roller are mounted, a thin layer of developer is formed on the surface of the developing roller, and the developing roller is brought into contact with the image forming body to form the image. In an electrophotographic process cartridge for forming a visible image on the surface of the image forming body by supplying the developer to the surface of the body,
An electrophotographic process cartridge, wherein the developing roller is the elastic roller for electrophotography according to claim 4. A thin layer of developer is formed on the surface of the developing roller, the developer roller is brought into contact with the image forming body, and the developer is supplied to the surface of the image forming body to form a visible image on the surface of the image forming body. In the image forming apparatus,
An image forming apparatus, wherein the developing roller is the elastic roller for electrophotography according to claim 4.

Images