JP2013020175A - Developing member, electrophotographic process cartridge, and electrophotographic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease so-called current value reduction in which carbon black moves by continuous use and a conductive pass is less likely to be obtained.SOLUTION: A developing member is provided, comprising at least a shaft core and a conductive elastic layer containing carbon black. The elastic layer has a sea-island structure having domains dispersed in a matrix. The matrix comprises a crosslinked rubber, while the domain comprises a thermoplastic resin. A content rate A of the carbon black included in a unit cross-sectional area of the matrix and a content rate B of the carbon black included in a unit cross-sectional area of the domain satisfy the relationship of A<B. An intermediate region is present between the domain and the matrix, and a content rate of the carbon black included in the unit cross-sectional area of the intermediate region is larger than the content rate A of the carbon black included in the unit cross-sectional area of the matrix and is smaller than the content rate B of the carbon black included in the unit cross-sectional area of the domain.

Description

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

  As an electrophotographic image developing system, a contact developing system using a non-magnetic one-component developer is widely used because it has advantages such as downsizing of an electrophotographic image forming apparatus.

  In this developing method, since the toner is moved by the electric charge, it is desired that the developing roller has a small electric current value attenuation and has a stable conductivity. In addition, the developing roller is desired to have appropriate flexibility and high dimensional accuracy in order to stabilize the contact state with the developing blade and the photosensitive drum.

  Conventionally, a conductive elastic layer mainly including a crosslinked rubber, which is excellent in compression set, wear resistance, and moldability and is inexpensive to manufacture, has been used for a developing roller used for contact development. . However, since the developing roller provided with such an elastic layer is used for continuous image formation, there is a case where a current value lowers that the current value of the developing roller attenuates while applying a DC voltage. A decrease in the current value of the developing roller with time may change the developing bias and cause density unevenness in the electrophotographic image.

  In order to solve such a problem, Patent Document 1 proposes an ionic conductive agent added. In Patent Document 2, a conductive foamed elastic body is composed of a sea-island structure of three kinds of crosslinked rubbers having different solubility parameter values (SP values), and two kinds of carbon blacks having different characteristics are dispersed therein. Has been proposed.

Japanese Patent Laid-Open No. 10-169641 Japanese Patent Laid-Open No. 10-254215

As a result of the study of the developing member according to the above-mentioned patent document, the present inventors have recognized that it is necessary to further improve the change in the electrical resistance of the developing member due to the application of a DC voltage over a long period of time. Obtained.
SUMMARY OF THE INVENTION An object of the present invention is to provide a developing member having excellent durability in which a current value is hardly lowered even when a DC voltage is applied over a long period of time.
Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus capable of stably forming a high-quality electrophotographic image.

This invention can solve the said subject by providing the following structure.
That is, a developing member having at least a shaft core and a conductive elastic layer containing carbon black, wherein the elastic layer has a sea-island structure in which domains are dispersed in the matrix, and the matrix is crosslinked. Rubber containing the thermoplastic resin, and the content of carbon black contained per unit cross-sectional area of the matrix is A, and the carbon black contained per unit cross-sectional area of the domain When the content rate is B, a carbon that satisfies the relationship of A <B, has an intermediate region between the domain and the matrix, and is contained per unit cross-sectional area of the intermediate region. The black content is higher than the carbon black content A contained per unit cross-sectional area of the matrix, and is contained per unit cross-sectional area of the domain. A developing member having an intermediate region less than the carbon black content B.

  The developing member of the present invention suppresses a decrease in current value due to energization, and allows excellent image formation with less uneven density and reduced density.

It is a figure explaining the cross section of the developing roller as a developing member which concerns on the Example of this invention. It is a figure explaining the measuring device which tests the electric current value which concerns on the Example of this invention, and an electric current value fall. 1 is a diagram illustrating an electrophotographic image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an electrophotographic process cartridge according to an embodiment of the present invention. It is a figure explaining the CVD processing apparatus which concerns on Example 27 of this invention. It is a figure explaining the state of the section cut in the perpendicular direction from the axial core object of the elastic layer concerning the example of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to embodiments, but the present invention is not limited to these examples.

[Development member]
A developing roller as a developing member in the present invention has an elastic layer 2 on a shaft core 1 as shown in FIG. Furthermore, the surface layer 3 may be provided on the outer periphery of the elastic layer 2. The elastic layer in the present invention is made of an elastic body and means a solid having the property of returning to its original shape when the stress is removed, although it is deformed by an external stress. Further, when the surface layer 3 is provided on the outer periphery of the elastic layer 2, the abrasion property by continuous image formation is improved, and a developing roller having excellent durability can be obtained.

  The concept of the elastic layer 2 in the present invention is shown in FIG. FIG. 6 is a view for explaining a state of a cross section cut in the vertical direction from the shaft core of the elastic layer according to the embodiment of the present invention. This elastic layer has a sea-island structure in which domains are dispersed in a matrix. The sea-island structure means a matrix 38 that is a continuous phase and a domain 36 that is a dispersed phase when two or more different materials are mixed. Further, the present invention is characterized in that an intermediate region 37 exists so as to surround the domain 36 between the matrix 38 and the domain. The intermediate region may be a continuous phase or a dispersed phase as long as it exists so as to surround the domain between the matrix and the domain.

  In the present invention, it has a matrix 38 containing a crosslinked rubber and a domain 36 containing a thermoplastic resin, and the content per unit cross-sectional area of the carbon black in the matrix is A, and the unit of the carbon black in the domain When the content per cross-sectional area is B, the relationship A <B is satisfied, and the content per unit cross-sectional area of carbon black between the domain and the matrix is the carbon in the matrix. It is characterized by having an elastic layer having an intermediate region 37 that is greater than the content A per unit cross-sectional area of black and less than the content B per unit cross-sectional area of the carbon black in the domain.

[mechanism]
The domain contains a thermoplastic resin. The thermoplastic resin has a melting point and a softening point. When the temperature of the thermoplastic resin reaches the melting point and the softening point, the thermoplastic resin is in a molten state, and is in a molten state before rubber that requires high shear for softening. It becomes. Therefore, carbon black is more easily present after kneading and molding than the crosslinked rubber, so that more carbon black is present. Furthermore, if the thermoplastic resin has a high SP value as a solubility parameter, the affinity with carbon black is improved, and more carbon black can be taken in. Incorporation of carbon black into the domain makes it difficult for carbon black to move, but when carbon black is concentrated and incorporated into the domain, the concentration of carbon black in the matrix decreases too much, and The difference in conductivity between the domains increases, and unevenness of the image occurs due to unevenness of the conductivity of the developing member. That is, the content per unit cross-sectional area of carbon black between the domains and the matrix is larger than the content A per unit cross-sectional area of carbon black in the matrix, and the units of the carbon black in the domains By having an intermediate region less than the content ratio B per cross-sectional area, the movement of the carbon black is suppressed, a decrease in the current carrying ratio is reduced, and the conductivity of the elastic layer due to excessive concentration of the carbon black in the domain is reduced. It is estimated that unevenness can be reduced and initial density unevenness can be reduced.

  In order to achieve the state in which the carbon black in the elastic layer is contained, the SP value is such that the crosslinked rubber contained in the matrix <the crosslinked rubber contained in the intermediate region <the thermoplastic resin contained in the domain, and It is preferable to become. In the elastic layer, the cross-linked rubber contained in the matrix, the cross-linked rubber contained in the intermediate region, and the thermoplastic resin contained in the domain have such an SP value, so that each material and carbon black It seems that such a configuration is easy to take due to the affinity of.

  In the present invention, it is particularly effective to contain polyvinyl chloride (PVC) resin in the domain, acrylonitrile-butadiene rubber in the intermediate region, and butadiene rubber in the matrix, particularly from the affinity with carbon black and durability.

  According to the study by the present inventors, the content of the thermoplastic resin used in the domain of the present invention in the elastic layer is preferably 10.0% by mass or more and 22.0% by mass or less. When the content of the thermoplastic resin in the domain is 10.0% by mass or more, the conductivity necessary for the developing member can be ensured. Further, when the content of the thermoplastic resin in the domain is 22.0% by mass or less, the ratio of the crosslinked rubber increases, whereby a developing member excellent in durability and wear resistance can be obtained. Furthermore, the content of the thermoplastic resin in the domain is preferably 35.0% by mass or more and 61.0% by mass or less. By containing the thermoplastic resin within this range, it becomes possible to take in the carbon black and suppress the movement of the carbon black.

  The shape of the domain may be any shape, and may be, for example, a spherical shape, a needle shape, a column shape, an indefinite shape, or the like. The average particle size of the domain is preferably in the range of 0.5 μm to 100 μm. When the average particle size of the domain is 0.5 μm or more, a development member in which the movement of carbon black is restricted and the current value is difficult to decrease is obtained. When the average particle size is 100 μm or less, the dispersion state of the domain is stable. In addition, a developing member having stable conductivity can be obtained. The particle diameter of the domain is derived from the average value of the major axis and the minor axis of the cross section of the domain, and the average particle diameter is obtained by calculating the number average.

  The content of the crosslinked rubber contained in the matrix in the present invention in the elastic layer is preferably 25% by mass or more and 50% by mass or less. If the content of the crosslinked rubber in the matrix is 25% by mass or more, the matrix can be formed stably, and if it is 50% by mass or less, formation of a conductive path can be ensured. Furthermore, the content of the crosslinked rubber in the matrix is preferably 84% by mass or more and 91% by mass or less. When the cross-linked rubber is contained in the matrix within this range, a stable sea-island structure can be obtained.

  The content of the crosslinked rubber contained in the intermediate region in the present invention in the elastic layer may be a content that can form an intermediate region between the domain and the matrix, but is preferably 9% by mass to 30% by mass. is there. If the content of the crosslinked rubber in the intermediate region is 9% by mass or more, an intermediate region capable of forming a carbon black conductive path can be formed, and if it is 30% by mass or less, a developing member excellent in current value reduction can be obtained. it can. Furthermore, the content of the crosslinked rubber in the intermediate region is preferably 58% by mass or more and 80% by mass or less. When the content of the cross-linked rubber in the intermediate region is within this range, it becomes possible to make the cross-linked rubber exist between the domain and the matrix, and it is possible to suppress a decrease in current value and to suppress a decrease in density and density unevenness. It becomes.

  The content of carbon black in the elastic layer in the present invention is preferably 10% by mass or more and 30% by mass or less. If the content of carbon black in the elastic layer is 10% by mass or more, the dispersed state in the domain, intermediate region and matrix can be stabilized, and the conductivity can be ensured. A member can be obtained.

  The current value of the developing member in the present invention is the state in which the SUS drum 6 is rotated at 60 rpm with a load 4 of 500 g applied to the exposed portion of the shaft core one by one at both ends by the measuring device shown in FIG. A voltage of 50 V is applied from the DC power source 8 and the internal resistance 7 is measured at 10 kΩ. The current value of the developing member is measured by the multimeter 5 in a state where the developing member is also rotated by following the SUS drum 6. The current value of the developing member is preferably from 50 μA to 3000 μA, and more preferably from 100 μA to 2000 μA. If the current value is 50 μA or more, density unevenness is unlikely to occur, and if it is 3000 μA or less, image defects due to leakage can be reduced. If the current value is 100 μA or more, the concentration is more stable, and if it is 2000 μA or less, the leakage can be further reduced. In the current value lowering state in the present invention, power is applied for 30 minutes with 50 V applied by the measuring device shown in FIG. 2, and the current value of the developing member before and after the current is compared as the current holding ratio (%). The retention rate (%) is 20% or more, more preferably 50% or more. When the energization current holding ratio (%) is 20% or more, it is possible to obtain a developing member that hardly affects development characteristics and is excellent in image formation. More preferably, the energization current holding ratio is 50% or more. Under this condition, in a practical test, the color laser printer LBP5400 (trade name, manufactured by Canon Inc.) corresponds to a printing state of 1000 sheets at a printing rate of 1%.

  The developing roller as the developing member in the present invention generally has an outer diameter in the range of 6.0 mm to 20.0 mm. When the outer diameter of the developing roller is 6.0 mm or more, bending is unlikely to occur, and when the developing roller is 20.0 mm or less, the developing roller can rotate stably.

  The developing member preferably has an ASKER-C hardness of 30 degrees or more and 80 degrees or less. When the ASKER-C hardness is 30 degrees or more, the contact state between the developing member and the developing blade or the photosensitive drum is stabilized. If the ASKER-C hardness is 80 degrees or less, the contact failure between the developing member and the photosensitive drum does not occur, and the adverse effects of the image such as white spots can be suppressed.

[Elastic layer material]
The SP value of the material used for the elastic layer in the present invention is a crosslinked rubber or a thermoplastic resin (a base that does not include a conductive agent, an additive, etc.) that is a base material that constitutes the matrix, domain, and intermediate region, respectively. SP value of the elastic material only).

The SP value in the present invention uses a calculated value by the following Small formula calculated from the chemical structure and density of the substance.
δ = ρΣF / M
F: Molecular aggregation energy constant of atoms and functional groups (aggregation energy x molecular volume) 1/2
M: Molecular weight of polymer repeating unit (structural unit) ρ: Density

Examples of the material for the elastic layer used in the present invention include the following.
As the thermoplastic resin applicable to the domain, a highly polar one having a high SP value is particularly suitable. The SP value of the thermoplastic resin used for the domain is preferably from 9.5 to 13.0. When the SP value is 9.5 or more, the affinity with carbon black is improved, and when the SP value is 13.0 or less, the affinity with the crosslinked rubber in the intermediate region is improved. Specific examples include the following thermoplastic resins. Polyvinyl chloride resin, polymethyl methacrylate resin, polyamide resin (polyamide 6, polyamide 66, MXD6, etc.), ethylene-vinyl acetate copolymer resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate. Of these, polyvinyl chloride resin is particularly preferred because of the affinity between carbon black and crosslinked rubber.

  As the crosslinked rubber applicable to the matrix, a crosslinked rubber having a small SP value is particularly suitable. The SP value of the crosslinked rubber used in the matrix is preferably less than 8.4. When the SP value is less than 8.4, the affinity with carbon black is lowered, and the SP tends to exist on the domain side or the intermediate region side. Specific examples include the following rubber materials. Isoprene rubber, butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, natural rubber. Of these, butadiene rubber is particularly suitable because of its durability and wear resistance.

  The SP value of the crosslinked rubber that can be used in the intermediate region between the matrix and the domain is preferably 8.5 or more and less than 9.4. Specific examples of the crosslinked rubber applicable to the region include styrene-butadiene rubber, acrylonitrile-butadiene rubber, and chloroprene rubber. Of these, acrylonitrile-butadiene rubber is preferred because of its affinity with high-polarity thermoplastic resins and carbon black contained in the domain.

  In the present invention, the SP values in the matrix, intermediate region, and domain in the elastic layer are preferably in the order of matrix <intermediate region <domain. With this configuration, the content per unit cross-sectional area of carbon black tends to be matrix <intermediate region <domain.

  Examples of carbon black applicable for imparting conductivity to these elastic layers include the following. Ketjen Black (registered trademark) EC, acetylene black, carbon for rubber, color carbon subjected to oxidation treatment, and conductive carbon such as pyrolytic carbon. As carbon for rubber, specifically, Super Abrasion Furnace (SAF), Intermediate Super Abrasion Furnace (ISAF), High Abrasion Furnace (HAF), Fast Extruding FurFace (FAF), Fast Extruding FurFace (HAF) (SRF), Fine Thermal (FT), and Medium Thermal (MT).

  The following are mentioned as a crosslinking agent used in the crosslinked rubber contained in the said matrix and intermediate | middle area | regions. Examples of the crosslinking agent include sulfur, 4,4′-dithiodimorpholine, tetraethylthiuram disulfide (TETD), dipentamethylene thiuram tetrasulfide (DPTT), tetrabutylthiuram disulfide (TBT), tetramethylthiuram disulfide (TMTD), tetrakis. Sulfur donors such as (2-ethylhexyl) thiuram disulfide (TOTD) and organic peroxide-based crosslinking agents can also be used. Examples of the organic peroxide-based crosslinking agent include the following. tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-bis (tert-butylperoxy) cyclododecane, 2,2-bis (tert-butylperoxy) octane 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 1,3-bis (tert-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (tert-butylperoxy) valerate, Benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate.

  Examples of the crosslinking accelerator used in the crosslinked rubber contained in the matrix and the intermediate region include the following compounds. Thiazole accelerators such as 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), 2- (4-morpholinodithio) benzothiazole (MDB), tetraethylthiuram disulfide (TETD), dipentamethylenethiuram tetrasulfide (DPTT), thiuram accelerators such as tetrabutyl thiuram disulfide (TBT), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOTD), and dibutyl dithiocarbamic acid Zinc (ZDBC), tellurium dimethyldithiocarbamate (TDEC), zinc dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC), etc. Sulfenamide accelerators such as thiocarbamate accelerators, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-oxyldiethylene-2-benzothiazolylsulfenamide (OBS), , 3 Diphenylguanidine (DPG), guanidine accelerators such as diortolyl guanidine (DOTG), and thiourea accelerators such as N, N′-ethylenethiourea (ETU) and N, N′-diethylthiourea (DETU).

  The total amount of these crosslinking agents and crosslinking accelerators is usually 0.01 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the rubber before crosslinking used for the elastic layer. When the total amount of the crosslinking agent and the crosslinking accelerator is 0.01 parts by mass or more, the crosslinking density is appropriately increased, and mechanical strength and low compression set can be ensured. Further, when the total amount of the crosslinking agent and crosslinking accelerator used is 20 parts by mass or less, a developing roller having elasticity without increasing the crosslinking density and high hardness can be obtained.

  Furthermore, various additives, such as a filler, antioxidant, anti-aging agent, or processing aid, can be used for the elastic layer as necessary.

  Examples of the filler include the following. Fumed silica, wet silica, quartz fine powder, diatomaceous earth, zinc oxide, magnesium carbonate, calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, glass fiber . The surface of these fillers may be hydrophobized by treatment with an organosilicon compound such as polydiorganosiloxane, and is not limited to these, and known materials can be used.

  The following are mentioned as antioxidant. Hindered phenolic antioxidants, phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants.

  Examples of the anti-aging agent include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

  A known material can be used as the processing aid, and examples thereof include fatty acids such as stearic acid and oleic acid, and metal salts and esters of fatty acids.

[Kneading of elastic layer]
The method for kneading the material forming the matrix, domain, and intermediate region in the elastic layer is not particularly limited as long as the elastic layer configuration according to the present invention can be produced, and conventionally known methods are used. Applicable. Specifically, mixing can be performed by using a single mixer or a combination of a static mixer, a two-roll mixer, a three-roll mixer, a kneader, a Banbury mixer, and a twin-screw extruder. . When the melting point of the thermoplastic resin used for the domain is high, the thermoplastic resin may be previously melted in a high-temperature furnace or the like and then charged into the mixer as described above.

[Molding of elastic layer]
The method for molding the elastic layer in the present invention can be produced by a conventionally known molding method such as an extrusion molding method or an injection molding method. The layer structure is not limited as long as it has the characteristics described in the present invention, and can be a structure of one layer or two or more layers. The thickness of the elastic layer may be within a preferable range of the outer diameter of the developing roller as the developing roller, but is preferably 1 mm or more and 5 mm or less. When the thickness of the elastic layer is 1 mm or more, the function as an elastic layer is good, the toner is hardly deteriorated, and when the thickness is 5 mm or less, the molding processability is stable, the shape is constant, and the image is uneven. It is difficult for harmful effects to occur.

[Surface layer]
In the present invention, when the surface layer is provided on the outer periphery of the elastic layer, the following organic and inorganic materials can be applied as the material.

  Examples of the organic surface layer material include the following resins. Polyamide resin; Fluorine resin; Styrenic resin; Vinyl resin; Polycarbonate resin; Acrylic resin; Polyethylene, polypropylene, Ethylene vinyl acetate copolymer polyolefin resin, etc .; Epoxy resin, polyester resin, alkyd resin, Thermosetting resins such as phenolic resin, melamine resin, polyurethane resin, urea resin, silicone resin, polyimide resin. Thermoplastic elastomers such as styrene, olefin, and urethane.

  Further, particles may be dispersed as a constituent material of the organic surface layer in order to facilitate toner transportation. Examples of the particles used for such purposes include polyurethane particles, polymethyl methyl methacrylate particles, silicone rubber particles, polystyrene particles, amino resin particles, phenol resin particles, and the like. Acid methyl particles and silicone rubber particles are preferred. These particles are preferably added in the range of 20 to 200 parts by mass of the binder resin of the surface layer.

  Furthermore, various additives such as a filler, an antioxidant, a conductive agent, an antiaging agent, or a processing aid can be used for the surface layer as necessary.

  Examples of the filler include the following. Fumed silica, wet silica, quartz fine powder, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate , Glass fiber. The surface of these fillers may be hydrophobized by treatment with an organosilicon compound such as polydiorganosiloxane, and is not limited to these, and known materials can be used.

  The following are mentioned as antioxidant. Hindered phenolic antioxidants, phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants.

  As the conductive agent, in the present invention, a conductivity-imparting agent based on an electronic conductive mechanism is suitable from the viewpoint of bleeding.

  Specific examples of the conductive agent based on the electronic conductive mechanism include metal powders such as aluminum, palladium, iron, copper, and silver, fibers, and carbon black. Examples of the conductive agent for the carbon black include acetylene black, ketjen black, PAN-based carbon black, pitch-based carbon black, and carbon nanotube. Among these conductive agents, the carbon black conductive agent is particularly preferable in terms of performance, quality, and cost. Examples of the anti-aging agent include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

  A known material can be used as the processing aid, and examples thereof include fatty acids such as stearic acid and oleic acid, and metal salts and esters of fatty acids.

  Examples of inorganic surface layer materials include silica films and carbon films. As the silica film, O—Si—O is a main skeleton, the proportion of Si and O in all elements is 60% or more, and Si is a silica film in which at least one of H, O, and C is bonded to Si. Can be mentioned. Examples of the carbon film include diamond-like carbon (DLC) which is a carbon thin film having high hardness, electrical insulation, and infrared transmission. The structure of DLC is an amorphous structure containing C as a main skeleton and containing some H, and a combination of both diamond bonds (SP3 bonds) and graphite bonds (SP2 bonds).

  Among these surface layer materials, a polyurethane resin is particularly suitable as the organic surface layer, and a silica film is particularly suitable as the inorganic surface layer from the viewpoint of durability.

  The thickness of these surface layers is appropriately selected depending on the type of surface layer to be formed and the forming method. In the case of an organic surface layer, the thickness is 3 μm or more and 1000 μm or less. If the thickness of the surface layer is 3 μm or more, durability can be secured, and if it is 1000 μm or less, a developing member capable of suppressing toner deterioration can be obtained. The thickness of the inorganic surface layer is preferably 0.01 μm or more and 3 μm or less. If the thickness of the surface layer is 0.01 μm or more, the elastic layer can be protected, and if it is 3 μm or less, a crack or the like of the surface layer can be suppressed and a developing member excellent in durability can be obtained.

  Examples of the method for forming the surface layer in the present invention include a method of forming by a coating method such as dip coating, spray coating, and roll coating. In addition, as a method for forming the inorganic surface layer, a known surface layer forming method such as a method formed by a plasma CVD method may be used.

  In the present invention, when the surface layer is provided, the outer periphery of the elastic layer is modified by corona treatment, frame treatment, UV treatment, and primer treatment in order to improve adhesion so that the elastic layer and the surface layer are not separated. You may quality.

[Shaft core]
As the shaft core, those conventionally used in this type of developing member can be used, and the material is not particularly limited as long as it has sufficient strength and conductivity.

[Electrophotographic process cartridge, electrophotographic image forming apparatus]
Next, an electrophotographic process cartridge and an electrophotographic image forming apparatus having a developing roller which is a developing member obtained by the manufacturing method of the present invention will be described.

  3 and 4 are cross-sectional views showing the schematic configuration of the electrophotographic image forming apparatus and the electrophotographic process cartridge of the present invention.

  In the electrophotographic image forming apparatus shown in FIG. 3, the paper 26 that is a transfer material is attracted to the transfer conveyance belt 24 that is held and driven by the drive roller 20, the tension roller 23, and the driven roller 25 by the paper feed roller 27. An image is formed by being supplied into the electrophotographic image forming apparatus by a roller 28. In the electrophotographic image forming apparatus, a photosensitive drum 9 used as a photosensitive member rotates, is uniformly charged by a charging roller 16 for charging the photosensitive drum 9, and writes an electrostatic latent image on the photosensitive drum 9. An electrostatic latent image is carried and formed on the surface of the laser beam 15 as a means. The electrostatic latent image is developed by applying a toner 12 by a developing device 14 arranged in contact with the photosensitive drum 9 used as a photosensitive member, and visualized as a toner image.

  The developing device 14 includes a developing container containing non-magnetic toner, and a developing roller 10 that carries the non-magnetic toner that is located in an opening extending in the longitudinal direction in the developing container and is placed opposite to the photosensitive drum 9. The electrostatic latent image on the photosensitive drum 9 is developed and visualized.

  The following toner can be used in the electrophotographic image forming apparatus of the present invention. That is, after kneading materials such as a binder resin, a release agent, a charge control agent, and a colorant, cooling and solidifying to obtain a resin composition, after pulverizing and classifying, the particle size distribution is made uniform Powder toner. Alternatively, a polymerized toner obtained by polymerizing a polymerizable monomer in an aqueous medium or the like.

  Development is so-called reversal development in which a toner image is formed on the exposed portion. The visualized toner image on the photosensitive drum 9 is transferred to a paper 26 as a recording medium by a transfer roller 21 supplied with a transfer bias from a bias power source 22. The paper 26 to which the toner image has been transferred is fixed by the fixing device 19 and is discharged out of the electrophotographic image forming apparatus, thus completing the printing operation.

  On the other hand, the toner 12 remaining on the photosensitive drum 9 without being transferred is scraped off by a cleaning blade 18 which is a cleaning member for cleaning the surface of the photosensitive drum 9 and stored in a waste toner container 17 and cleaned. 9 repeats the above operation.

  An example of an electrophotographic process cartridge is shown in FIG. In FIG. 4, the developing roller 10, the developing blade 13, the developing device 14, and the charging roller 16 are included, and the toner applying member 11 and the photosensitive drum 9 may be incorporated. The electrophotographic process cartridge includes at least a developing roller, a developing blade, and a developing device and is integrally held from the above members, and is detachably mounted on the main body of the electrophotographic image forming apparatus. As the structure of the toner application member 11, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon and polyamide are planted on the outer periphery of the shaft core body is used to supply toner to the developing roller 10 and to peel off undeveloped toner. It is preferable from the point of taking. For example, an elastic roller having a diameter of 16 mm in which polyurethane foam is provided on the outer periphery of the shaft core body can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. Moreover, when there was no description in the raw material, a commercially available reagent was used.

  In addition, about the measuring method of the physical property within description, it measured by the method as described below. The prescription of the elastic layer of the obtained developing roller is shown in Table 1, and the evaluation results are shown in Table 2 and Comparative Examples in Table 3.

[Example 1]
[Kneading of elastic layer material]
20 parts by mass of polyvinyl chloride resin KR600 (trade name, manufactured by Vitec) as the base material of the domain, 30 parts by mass of Nipol 401LL (trade name, manufactured by Nippon Zeon) of acrylonitrile-butadiene rubber as the base material of the intermediate region, 50 parts by mass of BR11 (trade name, manufactured by JSR) as a base material of the matrix, 30 parts by mass of Thermox Flow Foam N990 (trade name, manufactured by CANCAB) as carbon black, and calcium carbonate as a filler 5.0 parts by mass, 5 parts by mass of zinc oxide, and 1.0 part by mass of zinc stearate as a processing aid were kneaded in a 6-liter kneader TD6-15MDX (trade name, manufactured by Toshin). Thereafter, 1 part by mass of sulfur as a crosslinking agent and 1 part by mass of mercaptobenzothiazole (MBT) as a crosslinking accelerator were mixed in a 12-inch open roll (manufactured by Kansai Roll Co., Ltd.), and an uncrosslinked rubber composition of an elastic body I got a thing.

[Production and extrusion of elastic layer]
The obtained uncrosslinked rubber composition was extruded into a tube shape by a vent type rubber extruder (φ50 mm vent extruder L / D = 16, manufactured by EM Giken Co., Ltd.), and was heated at 160 ° C. with pressurized steam using a vulcanizing can. The vulcanization was performed for 1 minute to obtain a crosslinked rubber tube having an outer diameter of 14 mm, an inner diameter of 5.5 mm, and a length of 250 mm.
Next, Chemlock 459X (product in the axial direction central part 232 mm of the cylindrical surface of the cylindrical conductive shaft core (SUM22 (JIS symbol, sulfur composite free-cutting steel, nickel plated on the surface) with an outer diameter of 6 mm and a length of 252 mm) The above-mentioned crosslinked rubber tube was press-fitted into a primer coated with a name, manufactured by Rhode, and subjected to secondary vulcanization and adhesion treatment at a temperature of 160 ° C. for 2 hours in a hot air oven to obtain an elastic roller. Cut both ends of the rubber of the elastic roller after vulcanization to make the length of the rubber part 232 mm, and then use a GC80 grindstone to rotate the grinder LEO-600-F4L-BME (trade name, manufactured by Mizuguchi Seisakusho) A plurality of developing rollers having an elastic layer having a linear shape with an outer diameter of 12.00 mm were obtained, and the obtained developing rollers were used as samples for evaluation in the following evaluations.

[Measurement of carbon black content]
From the obtained elastic layer of the developing roller, the length of 232 mm is divided into four equal parts, and is cut into a width of 0.5 mm with a razor in a direction perpendicular to the shaft core. Was taken. A sample with an ultrathin section having a thickness of 100 nm was prepared using a microtome as an observation sample. The matrix / intermediate region / domain was confirmed from an observation image obtained by observing the sample with an electron microscope S-4800 (trade name, manufactured by Hitachi, Ltd.) at a magnification of 10,000 times. Further, using an energy dispersive X-ray analyzer (manufactured by EDAX) attached to the S-4800 (trade name, manufactured by Hitachi, Ltd.), carbon is obtained at an atomic ratio (Atomic%) at an acceleration voltage of 10 kV and an acquisition time of 100 seconds. Identified black.
An image photographed with an electron microscope is subjected to binarization processing by selecting only carbon black with image processing software PHOTOSHOP 6.0 (trade name, manufactured by Adobe), and a matrix based on a luminance histogram ratio of pixels in the image, The content of carbon black contained in each of the intermediate region and the domain was calculated.

[Measurement of current value of developing roller]
Using the measuring device shown in FIG. 2 in the environment of a temperature of 40 ° C. and a relative humidity of 95% RH, the obtained developing roller was applied with a load 4 of 500 g on the exposed portion of the shaft core one by one on both ends. With the SUS drum 6 rotated at 60 rpm, a voltage of 50 V was applied from the DC power source 8. With the developing roller also driven by the SUS drum 6 and rotated, the current value of the developing roller was measured by the multimeter 5 with the internal resistance 7 being 10 kΩ.

[Initial density unevenness]
The obtained developing roller was incorporated into an electrophotographic process cartridge for a color laser printer (trade name: LBP5400, manufactured by Canon Inc.). The process cartridge was then loaded into the color laser printer. Next, in an environment of a temperature of 20 ° C. and a relative humidity of 50%, A4 size paper (trade name: Canon Color Laser Copier Paper; basis weight 81.4 g / m ² , thickness 92 μm, whiteness 92%) 25 One halftone image having a% density was output, and the obtained halftone image was measured with a densitometer X-Rite 530 (trade name, manufactured by X-Rite) and evaluated according to the following criteria.
A: Maximum density-minimum value is less than 0.05.
B: Maximum density-minimum value of 0.05 to less than 0.10, and no density unevenness is observed on the halftone image.
C: Density unevenness occurs when the maximum value-minimum value of the density is 0.10 or more.

[Energization test]
Using the measuring device shown in FIG. 2 in an environment of a temperature of 40 ° C. and a relative humidity of 95% RH, the obtained developing roller was applied with a load 4 of 500 g on the exposed portion of the shaft core one by one on both ends. Then, a voltage was applied from the DC power source 8 while the SUS drum 6 was rotated at 60 rpm. With the developing roller also driven by the SUS drum 6 and rotated, the internal resistance 7 is set to 10 kΩ, the current value of the developing roller is measured by the multimeter 5, and the applied voltage is set so that the current value of the developing roller becomes 100 μA. After adjustment, power was supplied for 30 minutes.

[Current holding ratio]
The current value of the developing roller after energization was compared as (%) from the method for measuring the current value of the developing roller (current value after test / current value before test) as a current carrying ratio.
A: The current carrying ratio is 50% or more.
B: The current carrying ratio is 20% or more and less than 50%.
C: The energization current holding ratio is less than 20%.

[Density reduction after energization]
An unused developing roller was incorporated into an electrophotographic process cartridge for a color laser printer LBP5400 (trade name, manufactured by Canon Inc.). Next, in an environment of a temperature of 20 ° C. and a relative humidity of 50%, an image with a printing rate of 1% was printed on A4 size paper (Canon Color Laser Copier Paper; basis weight 81.4 g / m ² , thickness 92 μm, whiteness 92 %), One solid image was output. Next, after taking out the developing roller and conducting the energization test, it was incorporated into the LBP 5400 again, and one solid image was output in the same manner as described above. About the obtained solid image before and behind electricity supply, the average value of the density | concentration value measured 10 points | pieces from the solid image using the densitometer X-Rite530 (brand name, X-Rite company make) was evaluated on the following references | standards.
A: The amount of change in the density of the solid image is less than 0.1.
B: The change amount of the density of the solid image is 0.1 or more and less than 0.2.
C: The amount of change in the density of the solid image is 0.2 or more.

[Development roller wear after endurance]
The obtained developing roller was incorporated into an electrophotographic process cartridge for a color laser printer LBP5400 (trade name, manufactured by Canon Inc.). The electrophotographic process cartridge was incorporated into the main body of LBP5400. Next, in an environment of a temperature of 20 ° C. and a relative humidity of 50%, an image with a printing rate of 1% was printed on A4 size paper (Canon Color Laser Copier Paper; basis weight 81.4 g / m ² , thickness 92 μm, whiteness 92 %) Was output to 1000 sheets. After that, the developing roller was taken out, the surface wear state was observed, and the following criteria were evaluated.
A: There is no wear on the developing roller.
B: Some wear is observed at the end of the developing roller.
C: The developing roller is worn.

[Density unevenness of halftone after endurance]
The obtained developing roller was incorporated into an electrophotographic process cartridge for a color laser printer LBP5400 (trade name, manufactured by Canon Inc.). The electrophotographic process cartridge was incorporated into the main body of LBP5400. Next, in an environment of a temperature of 20 ° C. and a relative humidity of 50%, an image with a printing rate of 1% was printed on A4 size paper (Canon Color Laser Copier Paper; basis weight 81.4 g / m ² , thickness 92 μm, whiteness 92 %)), And a halftone image obtained by outputting a single 25% halftone image, nine points were measured using a densitometer X-Rite 530 (trade name, manufactured by X-Rite). Evaluation was made according to the following criteria.
A: Maximum density-minimum value is less than 0.10.
B: Maximum density-minimum value of 0.10 or more and less than 0.15, no density unevenness is observed on the halftone image.
C: Density unevenness occurs when the maximum value-minimum value of the density is 0.15 or more.

※１ カーボンブラック、サーマックスフローフォームＮ９９０（商品名、ＣＡＮＣＡＢ社製）
※２ カーボンブラック、７３６０ＳＢ（商品名、東海カーボン社製）
※３ カーボンブラック、ＨＳ５００（商品名、東海カーボン社製）
※４ カーボンブラック、シーストＧＳＯ（商品名、東海カーボン社製）
※５ ＰＶＣ樹脂、ＫＲ６００（商品名、ヴィテック社製）
※６ ＰＭＭＡ樹脂、アクリペットＶ００１（商品名、三菱レイヨン社製）
※７ ポリアミド６樹脂（ＰＡ６）、Ａ１０３０ＢＲＬ（商品名、ユニチカ社製）
※８ ＬＤＰＥ樹脂、スミカセンＧ８０１（商品名、住友化学社製）
※９ アクリロニトリル−ブタジエンゴム（１８％ＮＢＲ）、ニポール４０１ＬＬ（商品名、日本ゼオン社製；ニトリル１８質量％）
※１０ アクリロニトリル−ブタジエンゴム（２９％ＮＢＲ）、ニポール１０４３（商品名、日本ゼオン社製；ニトリル２９質量％）
※１１ アクリロニトリル−ブタジエンゴム（４０．５％ＮＢＲ）、ニポール１０４１（商品名、日本ゼオン社製
※１２ スチレン−ブタジエンゴム（２３.５％ＳＢＲ）、１５０２（商品名、ＪＳＲ社製；スチレン量２３．５質量％）
※１３ クロロプレンゴム（ＣＲ）、ネオプレンＷＲＴ（商品名、デュポンダウエラストマー社製）
※１４ エチレン−プロピレン−ジエンゴム（ＥＰＤＭ）、エスプレン５０５Ａ（商品名、住友化学社製）
※１５ イソプレンゴム（ＩＲ）、ＩＲ２２００（商品名、ＪＳＲ社製）
※１６ ブタジエンゴム（ＢＲ）、ＢＲ１１（商品名、ＪＳＲ社製）

* 1 Carbon black, Thermax Flow Form N990 (trade name, manufactured by CANCAB)
* 2 Carbon black, 7360SB (trade name, manufactured by Tokai Carbon Co., Ltd.)
* 3 Carbon black, HS500 (trade name, manufactured by Tokai Carbon Co., Ltd.)
* 4 Carbon black, seast GSO (trade name, manufactured by Tokai Carbon Co., Ltd.)
* 5 PVC resin, KR600 (trade name, manufactured by Vitec)
* 6 PMMA resin, Acrypet V001 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.)
* 7 Polyamide 6 resin (PA6), A1030BRL (trade name, manufactured by Unitika)
* 8 LDPE resin, Sumikasen G801 (trade name, manufactured by Sumitomo Chemical Co., Ltd.)
* 9 Acrylonitrile-butadiene rubber (18% NBR), Nipol 401LL (trade name, manufactured by Nippon Zeon Co., Ltd .; Nitrile 18% by mass)
* 10 Acrylonitrile-butadiene rubber (29% NBR), Nipol 1043 (trade name, manufactured by ZEON Corporation; nitrile 29% by mass)
* 11 Acrylonitrile-butadiene rubber (40.5% NBR), Nipol 1041 (trade name, manufactured by Nippon Zeon) * 12 Styrene-butadiene rubber (23.5% SBR), 1502 (trade name, manufactured by JSR; styrene content 23 .5% by mass)
* 13 Chloroprene rubber (CR), Neoprene WRT (trade name, manufactured by DuPont Dow Elastomer)
* 14 Ethylene-propylene-diene rubber (EPDM), Esprene 505A (trade name, manufactured by Sumitomo Chemical Co., Ltd.)
* 15 Isoprene rubber (IR), IR2200 (trade name, manufactured by JSR)
* 16 Butadiene rubber (BR), BR11 (trade name, manufactured by JSR)

[Examples 2 to 17]
The elastic layer was molded and evaluated in the same manner as in Example 1 except that the raw material used for the elastic layer was changed to the material shown in Table 1. PMMA used for the domains of Examples 2 to 5 and Examples 14 to 17 and polyamide 6 used for the domains of Examples 6 to 9 were previously melted in a high-temperature furnace and mixed with other materials in a 6 liter kneader. TD6-15MDX (trade name, manufactured by Toshin Co., Ltd.) was used.

[Examples 18 to 26]
The elastic rollers obtained in Examples 1 to 9 were each polished to an outer diameter of 11.98 mm, and a surface layer was produced by the following method to obtain a two-layer developing roller. Otherwise, the evaluation was performed in the same manner as in Example 1.

[Production of surface layer]
As the material for the surface layer, Nippon Run 5033 (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is used, and the isocyanate coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is used as the curing agent to make 100 parts by mass. ] / [OH] molar ratio was set to 1.2. Further, 30 parts by mass of carbon black MA100 (trade name, manufactured by Mitsubishi Chemical Corporation) was added. An organic solvent was added to the raw material mixture, and 5 parts by mass of polyurethane particles CFB-101-40 (trade name, manufactured by Dainippon Ink & Chemicals, Inc.) were added and uniformly dispersed and mixed to obtain a raw material liquid for the surface layer.
In this resin raw material liquid, the developing rollers obtained in Examples 1 to 9 were respectively immersed and coated, then pulled up and dried, and heat-treated at a temperature of 160 ° C. for 20 minutes, whereby a surface layer having a thickness of 10 μm. Was developed on the outer periphery of the elastic roller.

Example 27
The elastic roller obtained in the same manner as in Example 1 was installed in the plasma CVD apparatus for the parallel plate electrode 29 shown in FIG. 5 so that the distance from the parallel plate electrode 29 was 50 mm, and then the vacuum pump 34 was used. The inside of the vacuum chamber 33 was depressurized to 0.01 pa. Thereafter, 1.0 sccm of hexamethyldisiloxane vapor is supplied as a source gas from the gas supply unit 30 (where “sccm” represents a volume flow rate of 1 cm ³ per minute when the source gas is at a temperature of 0 ° C. and 1 atm. .), A mixed gas of 22.5 sccm of argon gas was introduced from the oxygen and rare gas supply unit 31 into the vacuum chamber 33, and the pressure in the vacuum chamber 33 was adjusted to 1.0 Pa. After the pressure becomes constant, the high-frequency power source 35 supplies power with a frequency of 13.56 MHz and 70 w to the parallel plate electrodes 29 having a length of 300 mm and a total area of the discharge part of 120 cm ^2. A plasma was generated. An elastic roller having an elastic layer installed in the vacuum chamber 33 was rotated at 30 rpm by a rotating device 32, and was processed for 300 seconds to form a surface layer having a thickness of 1 μm to obtain a developing roller. The obtained developing roller was evaluated in the same manner as in Example 1.
In addition, when the elemental ratios O / Si and C / Si on the surface of the coating film of the developing roller of this example were subjected to component analysis using an X-ray photoelectron spectrometer Quantum 2000 (trade name, manufactured by ULVAC-PHI), 1. The silica films were 56 and 0.32.

[Examples 28 to 30]
A developing roller was prepared and evaluated in the same manner as in Example 1 except that the amount of carbon black added in Example 1 was changed to 40 parts by mass, 50 parts by mass, or 20 parts by mass.

[Examples 31-33]
A developing roller was prepared and evaluated in the same manner as in Example 1 except that the carbon black of Example 1 was changed to the following.
Example 31: 7360SB (trade name, manufactured by Tokai Carbon Co., Ltd.)
Example 32: HS500 (trade name, manufactured by Tokai Carbon Co., Ltd.)
Example 33: Seast GSO (trade name, manufactured by Tokai Carbon Co., Ltd.).

Example 34
Evaluation was performed in the same manner as in Example 1 except that Nipol 401LL (trade name, manufactured by Nippon Zeon Co., Ltd.) was not added as a material for the intermediate region from Example 1 but Nipol 1041 (trade name, manufactured by Nippon Zeon Co., Ltd.) was added. It was.

[Examples 35 to 40]
A developing roller was prepared by changing the amount of each material added from Example 1 to the amount shown in Table 1, and evaluated in the same manner as in Example 1.

[Comparative Example 1]
Except adding PVC KR600 (trade name, manufactured by Vitec) from Example 1 and forming an elastic layer with 40 parts by mass of Nipol 401LL (trade name, manufactured by Nippon Zeon Co., Ltd.) as an intermediate region material. Evaluation was performed in the same manner as in Example 1.

[Comparative Example 2]
An elastic layer is formed from 90 parts by mass of butadiene rubber BR11 (trade name, manufactured by JSR) as a matrix material without adding Nipol 401LL (trade name, manufactured by ZEON CORPORATION) as a material for the intermediate region from Example 1. Evaluation was performed in the same manner as in Example 1 except that.

[Comparative Example 3]
Evaluation was performed in the same manner as in Example 1 except that Example 1 was changed to Nipol 1041 (trade name, manufactured by Nippon Zeon Co., Ltd.) as the material for the intermediate region.

[Comparative Example 4]
Evaluation was performed in the same manner as in Example 1 except that the low-density polyethylene Sumikacene G801 (trade name, manufactured by Sumitomo Chemical Co., Ltd.) was used as the domain thermoplastic resin from Example 1.

[Comparative Example 5]
Evaluation was carried out in the same manner as in Example 1 except that Example 11 was changed to Nipol 1041 (trade name, manufactured by Nippon Zeon Co., Ltd.) without adding BR11 as a rubber material for the matrix.

DESCRIPTION OF SYMBOLS 1 ... Shaft core body 2 ... Elastic layer 3 ... Surface layer 36 ... Domain 37 ... Intermediate region 38 ... Matrix

Claims (5)

A developing member having a shaft body and a conductive elastic layer containing carbon black,
The elastic layer has a sea-island structure in which domains are dispersed in a matrix,
The matrix includes a crosslinked rubber;
The domain includes a thermoplastic resin, and
When the content of carbon black per unit cross-sectional area of the matrix is A and the content of carbon black per unit cross-sectional area of the domain is B, the relationship of A <B is satisfied, and
Having an intermediate region between the domain and the matrix;
The intermediate region has a carbon black content per unit cross-sectional area greater than the carbon black content A contained per unit cross-sectional area of the matrix, and is contained per unit cross-sectional area of the domain. A developing member characterized by being less than the carbon black content B.   The matrix contains a crosslinked rubber, the SP value of the crosslinked rubber contained in the matrix is smaller than the SP value of the thermoplastic resin contained in the domain, and the intermediate region contains a crosslinked rubber. And an SP value of the crosslinked rubber contained in the intermediate region is smaller than an SP value of the thermoplastic resin contained in the domain and larger than an SP value of the crosslinked rubber contained in the matrix. The developing member according to claim 1.   The developing member according to claim 1, wherein the intermediate region contains acrylonitrile-butadiene rubber, the matrix contains butadiene rubber, and the domain contains polyvinyl chloride resin.   4. An electrophotographic process cartridge in which at least a developing member, a developing blade, and a developing device are integrated and detachably attached to an electrophotographic image forming apparatus main body to form an image, wherein the developing member is any one of claims 1 to 3. An electrophotographic process cartridge which is the developing member according to the item.   A developing member that carries toner in a state of being in contact with the photosensitive member carrying the latent image is provided, and the developing member applies toner to the photosensitive member to visualize the latent image formed on the photosensitive member as a toner image. 4. The electrophotographic image forming apparatus according to claim 1, wherein the developing member is the developing member according to claim 1.

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