Electrophotographic roller, process cartridge, and electrophotographic image forming apparatus

Abstract

The invention relates to an electrophotographic roller, a process cartridge, and an electrophotographic image forming apparatus. An electrophotographic roller having a conductive substrate and a resin layer on an outer peripheral surface of the substrate, in which the thickness of the resin layer is 2.0-30.0 [mu] m, the resin layer contains a binder resin and carbon black dispersed in the binder resin, the arithmetic mean Rc of the equivalent circle diameter of the carbon black in the resin layer is 80 nm or less, and the thickness of the resin layer is 2.0-30.0 [mu] m. The arithmetic mean value d of the distance between the wall surfaces of the carbon black in the resin layer is 60-170 nm, and when the elastic modulus of the binder resin in a first region from the outer surface of the resin layer to a depth of 0.1 [mu] m as measured in a cross section in the thickness direction of the resin layer is defined as E1, E1 satisfies E1 > = 200 MPa.

Description

Technical Field

[0001] This disclosure relates to an electrophotographic roller, a processing box, and an electrophotographic image forming apparatus. Background Technology

[0002] In electrophotographic image forming equipment (e.g., copiers, fax machines, or printers using electrophotographic methods), an image carrier is charged by a charging roller, and an electrostatic latent image is formed by a laser. Next, toner from the developing container is applied to the developing roller via a toner supply roller and a toner layer thickness control component, and development occurs with the toner when the image carrier and the developing roller are in contact or close to each other. Afterward, the toner on the image carrier is transferred to recording paper by a transfer means, fixed by heat and pressure, and any residual toner on the image carrier is removed by a cleaning blade. In recent years, with the increasing demand for longer lifespans in electrophotographic image forming equipment, higher durability is also required for electrophotographic rollers.

[0003] For example, as the lifespan of electrophotographic image forming equipment becomes very long, the surface of conventional developing rollers may be worn and scratched due to repeated friction, and the functions required for electrophotography may be impaired.

[0004] For example, in the case of developing rollers, the surface may be worn and scratched due to repeated friction. It is difficult to form high-quality electrophotographic images using such developing rollers. Furthermore, in the case of charging rollers, the formation of scratches may reduce charge uniformity, and the electrophotographic image may become coarse over time. To achieve continuous and stable output of high-quality electrophotographic images over long periods, electrophotographic rollers that suppress scratches caused by abrasion at a higher level are required; in other words, electrophotographic rollers with excellent durability are required.

[0005] In Japanese Patent Application Publication No. 2020-008847, an interpenetrating polymer network structure (hereinafter referred to as IPN structure) of crosslinked urethane resin and crosslinked acrylic resin is formed near the outer surface. This allows for the suppression of scratches caused by abrasion even during durable use when printing a large number of sheets of paper at high temperatures. Summary of the Invention

[0006] According to the research conducted by the inventors, there is still room for improvement in the scratch resistance of the electrophotographic roller described in Japanese Patent Application Publication No. 2020-008847. Specifically, for example, prolonged and repeated use in high and low temperature environments may cause scratches caused by grinding to propagate inward and become cracks.

[0007] This disclosure provides an electrophotographic roller that suppresses scratches caused by grinding and cracks caused by the propagation of scratches inward, even during prolonged and repeated use in high and low temperature environments. This disclosure also provides a processing cartridge that contributes to the stable formation of high-quality electrophotographic images. This disclosure further provides an electrophotographic image forming apparatus capable of forming high-quality electrophotographic images.

[0008] This disclosure relates to an electrophotographic roller having a conductive substrate and a resin layer on the outer peripheral surface of the substrate, wherein the thickness of the resin layer is 2.0 to 30.0 μm, the resin layer comprises a binder resin and carbon black dispersed in the binder resin, the arithmetic mean of the circumferential equivalent diameter Rc of the carbon black in the resin layer is less than 80 nm, the arithmetic mean of the distance d between the walls of the carbon black in the resin layer is 60 to 170 nm, and when the elastic modulus of the binder resin in a first region from the outer surface of the resin layer to a depth of 0.1 μm, as measured in a cross section in the thickness direction of the resin layer, is defined as E1, E1 satisfies the following equation (1): E1≥200MPa ... (1).

[0009] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is illustrated by way of example. Attached Figure Description

[0010] Figure 1 This is a schematic cross-sectional view showing an example of an electrophotographic roller according to the present disclosure.

[0011] Figure 2 This is a schematic cross-sectional view showing another example of an electrophotographic roller according to the present disclosure.

[0012] Figure 3 This is a schematic diagram of an electrophotographic image forming apparatus according to the present disclosure.

[0013] Figure 4 This is a schematic diagram of the processing box according to this disclosure.

[0014] Figure 5 It is a cross-sectional view of the electrophotographic roller according to this disclosure. Detailed Implementation

[0015] In this disclosure, unless otherwise specified, the notation "from XX to YY" and "XX to (~)YY" for a numerical range refers to a numerical range that includes the lower and upper limits of the range as endpoints. When describing a numerical range in stages, the upper and lower limits of each numerical range can be combined arbitrarily. In this disclosure, for example, the expression "at least one selected from the group consisting of XX, YY, and ZZ" covers XX, YY, and ZZ, combinations of XX and YY, combinations of XX and ZZ, combinations of YY and ZZ, and combinations of XX, YY, and ZZ.

[0016] According to the inventor's research, there is room for improvement in the scratch resistance of the electrophotographic roller described in Japanese Patent Application Publication No. 2020-008847 when used in low-temperature environments. Specifically, for example, prolonged and repeated use in high and low temperature environments may cause scratches caused by grinding to propagate inward and become cracks.

[0017] The electrophotographic roller according to Japanese Patent Application Publication No. 2020-008847 exhibits strength and flexibility due to the formation of an IPN structure of cross-linked urethane resin and cross-linked acrylic resin near its outer surface. In the IPN structure, two or more polymer network structures are intertwined and interwoven without covalent bonding. In the embodiment according to Japanese Patent Application Publication No. 2020-008847, a cross-linked acrylic resin with a higher elastic modulus than the cross-linked urethane resin is used as a second polymer to form the network for the cross-linked urethane. As a result, scratches caused by abrasion can be suppressed during durable use, printing a large number of sheets in a high-temperature environment.

[0018] However, the IPN structure of cross-linked urethane resins and cross-linked acrylic resins may lose toughness and become brittle at low temperatures, and existing scratches may propagate inward and turn into cracks.

[0019] As a result of extensive research, the inventors deduced that in order to obtain an electrophotographic roller capable of suppressing scratches and cracks caused by grinding during prolonged and repeated use in high and low temperature environments, the following two requirements need to be met simultaneously.

[0020] Requirement (1)

[0021] When the elastic modulus of the binder resin in the first region from the outer surface of the resin layer to a depth of 0.1 μm, which is measured in a cross section in the thickness direction of the resin layer of the electrophotographic roller, is expressed as E1, E1 satisfies the following formula (1).

[0022] E1≥200MPa ... (1).

[0023] Requirement (2)

[0024] The resin layer of the electrophotographic roller comprises a binder resin and carbon black dispersed in the binder resin. The arithmetic mean of the spherical equivalent diameter Rc of the carbon black in the resin layer is less than 80 nm, and the arithmetic mean of the distance d between the walls of the carbon black in the resin layer is 60 nm to 170 nm.

[0025] The requirements (1) and (2) above are explained in detail below.

[0026] Technical significance of requirement (1)

[0027] Requirement (1) specifies the modulus of elasticity in the region from the outer surface of the electrophotographic roller to a depth of 0.1 μm. A high modulus of elasticity in this region indicates high hardness of the outermost surface of the electrophotographic roller. Since resin materials typically soften at high temperatures, friction is higher at high temperatures than at room temperature. Prolonged use of an electrophotographic roller with a resin layer having a low modulus of elasticity in such a high-temperature environment will result in scratches due to abrasion.

[0028] The elastic modulus E1 is 200 MPa or more, preferably 250 MPa or more, and more preferably 400 MPa or more. There is no specific upper limit for the elastic modulus E1, but it is, for example, 600 MPa or less, and 550 MPa or less. The elastic modulus E1 is preferably 200 MPa to 600 MPa, more preferably 250 MPa to 600 MPa, and even more preferably 400 MPa to 600 MPa.

[0029] By setting the elastic modulus E1 within this range, scratches caused by grinding can be suppressed to an extremely high level, even when the roller is used for a long time in a high-temperature environment.

[0030] Technical significance of requirement (2)

[0031] Requirement (2) specifies the dispersibility of carbon black contained in the resin layer of an electrophotographic roller. In electrophotographic rollers, a method is appropriately used to disperse carbon black in the resin layer to obtain conductivity. It is highly likely that the aforementioned cracks occur in a low-temperature environment where the toughness of the resin layer decreases due to the propagation of scratches from the starting point along the resin-carbon black interface. As a result of extensive research, the inventors have discovered that by highly dispersing carbon black in the resin layer, the propagation of scratches along the resin-carbon black interface can be suppressed.

[0032] According to Requirement 1, by increasing the elastic modulus in the region from the outer surface to a depth of 0.1 μm to over 200 MPa, the occurrence of scratches due to grinding can be suppressed to a very high level. Meanwhile, in low-temperature environments, the toughness in the region from the outer surface to a depth of 0.1 μm is likely to decrease, thus existing scratches will extend deeper and cracks will form.

[0033] In this disclosure, the arithmetic mean Rc of the spherical equivalent diameter of the carbon black in the resin layer is 80 nm or less, and the arithmetic mean d of the distance between the walls of the carbon black in the resin layer is 60 nm to 170 nm. When Rc and d are set within the above ranges, even in a resin layer with reduced toughness, scratches are less likely to propagate inward, thus suppressing crack formation.

[0034] The scratches extend along the carbon black-resin layer interface. Therefore, it is conceivable that when Rc is outside the aforementioned range, the carbon black-resin layer interface is likely to be continuous, and the scratches are likely to extend. Furthermore, when d is less than 60 nm, adjacent carbon black particles are close to each other, and the scratches are likely to extend along them. When d exceeds 170 nm, adjacent carbon black particles are too far apart, and it is considered difficult to achieve good conductivity in the resin layer.

[0035] The arithmetic mean value Rc of the equivalent diameter of the circle is preferably less than 60 nm. Rc is, for example, 30 nm to 80 nm, preferably 40 nm to 65 nm, more preferably 40 nm to 60 nm, and even more preferably 50 nm to 60 nm.

[0036] The arithmetic mean d of the distance between the walls is preferably 80 nm to 150 nm, more preferably 100 nm to 130 nm. By setting this value within the above range, it is easier to suppress the formation of scratches and cracks.

[0037] To achieve the effects of this disclosure, it is important to simultaneously satisfy the above requirements. By simultaneously satisfying requirements (1) and (2), scratches caused by grinding and cracks caused by the propagation of scratches inward can be suppressed even during prolonged and repeated use in high and low temperature environments. If requirement (1) is not satisfied, scratches caused by grinding cannot be suppressed, and if requirement (2) is not satisfied, cracks caused by the propagation of scratches inward cannot be suppressed. The selection of suitable materials and manufacturing conditions for satisfying requirements (1) and (2) will be described below.

[0038] This disclosure will now be described in detail.

[0039] Electrophotographic roller

[0040] The electrophotographic roller has a conductive substrate and a resin layer on the outer peripheral surface of the substrate. The resin layer is at least one layer, but may be a single layer. Preferably, the resin layer forms the outer surface of the electrophotographic roller. The substrate and the resin layer may be in direct contact with each other, or other layers may exist between the substrate and the resin layer.

[0041] Figure 1 An example of an electrophotographic roller is shown. Figure 1 In the electrophotographic roller 11 shown, a resin layer 13 is laminated on the outer peripheral surface of a rod-shaped or hollow cylindrical substrate 12. The layer composition of the electrophotographic roller is not limited to... Figure 1 The layer structure is shown. This is another form of electrophotographic roller. Figure 2 An example is an electrophotographic roller having an intermediate layer 14 between a substrate 12 and a resin layer 13 disposed on its outer peripheral surface.

[0042] matrix

[0043] The substrate is conductive and functions as a support member for the electrophotographic roller, and in some cases, it also serves as an electrode. Specific examples of the substrate are preferably solid rod-shaped or hollow cylindrical substrates.

[0044] The materials constituting the matrix can be suitably selected from those known in the field of conductive components for electrophotography and materials that can be used as electrophotographic rollers. Examples include metals or alloys, such as aluminum and stainless steel, carbon steel alloys, conductive synthetic resins, and iron and copper alloys.

[0045] Furthermore, the material constituting the substrate can undergo oxidation treatment, chromium plating, or nickel plating, etc. As for the type of plating, electroplating or electroless plating can be used. From the viewpoint of dimensional stability, electroless plating is preferred. The types of electroless plating used in this article include nickel plating, copper plating, gold plating, and various other alloy platings. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention, the plating thickness is preferably 0.1 μm to 30 μm.

[0046] A primer can be applied to the surface of a substrate to improve adhesion between the substrate and the resin layer. Known primers can be selected and used depending on the materials of the rubber material used to form the conductive layer and the support. Examples of primer materials include thermosetting and thermoplastic resins; specifically, materials such as phenolic resins, polyurethanes, acrylic resins, polyester resins, polyether resins, and epoxy resins can be used.

[0047] In non-magnetic single-component contact developing processes, an electrophotographic roller in which an intermediate layer 14 is laminated between a substrate 12 and a resin layer 13 can be suitably used. The intermediate layer is preferably formed from a molded body of a conventional rubber material.

[0048] Examples of rubber materials include the following: ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluororubber, silicone rubber, epichlorohydrin rubber, hydrogenated NBR, and urethane rubber. These can be used alone or in combination of two or more.

[0049] resin layer

[0050] Adhesive resin

[0051] The resin layer comprises an adhesive resin. Known adhesive resins can be used as the adhesive resin. Preferably, the adhesive resin comprises a cross-linked urethane resin, which has excellent flexibility and strength, and facilitates the formation of the IPN structure described later.

[0052] Urea resins can be obtained from urethane raw materials comprising polyols, isocyanates, and chain extenders as needed. Urea resins can be cured products of urethane raw materials, or cured products of mixtures of urethane raw materials comprising urethane raw materials and additives such as surface modifiers and roughening particles. Examples of polyols used as raw materials for urethane resins include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, and mixtures thereof. Among these, polycarbonate polyols are preferred.

[0053] Examples of isocyanates used as raw materials for urethane resins include the following: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), benzyltoluidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), cyclohexane diisocyanate, polymeric MDI, and mixtures thereof.

[0054] In the above, polymeric MDI is preferred. As mentioned herein, polymeric MDI is a mixture of monomeric MDI and high molecular weight polyisocyanate, and is represented by the following formula (A). In formula (A), n is preferably 0 to 4.

[0055] Commercially available polymeric MDIs can be used, and examples include the Millionate MR series (manufactured by Tosoh Corporation), such as Millionate MR400 (product name).

[0056]

[0057] Chain extenders used as raw materials for urethane resins include difunctional low-molecular-weight diols such as ethylene glycol, 1,4-butanediol, and 3-methylpentanediol, and trifunctional low-molecular-weight triols such as trimethylolpropane, as well as mixtures thereof. Prepolymer-type isocyanate compounds with terminal isocyanate groups, obtained by reacting the aforementioned isocyanate compounds with various polyols in an excess of isocyanate groups, can also be used. Materials in which the isocyanate groups are capped with various end-capping agents such as MEK oxime can also be used.

[0058] Regardless of the material used, urethane resins can be obtained by reacting polyols with isocyanates through heating. Furthermore, when either or both of the polyol and isocyanate have a branched structure and possess three or more functional groups, the resulting urethane resin becomes a cross-linked urethane resin.

[0059] Furthermore, from the viewpoint of the elastic modulus of the resin layer, it is preferable that the adhesive resin comprises a cross-linked urethane resin having a polycarbonate structure. By using a cross-linked urethane resin having a polycarbonate structure, E1 and E2 can be easily controlled within appropriate ranges.

[0060] For example, by using analysis with pyrolysis GC / MS, FT-IR, or NMR, it can be confirmed that the polymer contained in the resin layer of the electrophotographic roller is a cross-linked urethane resin with a polycarbonate structure.

[0061] Crosslinked (meth)acrylic resins

[0062] Crosslinked (meth)acrylic resins (hereinafter referred to as "crosslinked acrylic resins") are harder than crosslinked urethane resins, thus increasing the hardness of the outermost surface. However, crosslinked acrylic resins are brittle when used alone and are prone to scratching due to abrasion caused by friction. Meanwhile, when the IPN structure described later is introduced into or near the outer surface of the resin layer, brittleness is less likely, and high strength can be imparted while maintaining flexibility.

[0063] The resin layer preferably comprises cross-linked urethane resin and cross-linked acrylic resin. The cross-linked urethane resin is preferably used as an adhesive resin in the resin layer. In the resin layer, the cross-linked urethane resin and the cross-linked acrylic resin preferably form an interpenetrating polymer network (IPN) structure.

[0064] An IPN structure is defined as a structure in which two or more polymeric compounds intertwine and interweave in a network structure without being connected by covalent bonds. The IPN structure in the resin layer is preferably formed by incorporating a cross-linked acrylic resin into a three-dimensional cross-linked network of a cross-linked urethane resin.

[0065] Crosslinked acrylic resins are formed by the polymerization of (meth)acrylic monomers. The (meth)acrylic monomers mentioned herein refer to both acrylic monomers and methacrylic monomers. In other words, crosslinked acrylic resins are formed by polymerizing one or both of acrylic monomers and methacrylic monomers.

[0066] In order to form an IPN structure with the crosslinked urethane resin on and near the outer surface of the resin layer, it is preferable to impregnate the resin layer containing the crosslinked urethane with a liquid (meth)acrylic monomer and then cure it.

[0067] The types of (meth)acrylic monomers used in this article include polyfunctional monomers having multiple acryloyl or methacryloyl groups as functional groups to form a cross-linked structure. However, when the number of functional groups is four or more, the viscosity of the (meth)acrylic monomer increases, making it difficult for the monomer to penetrate to the surface of the resin layer made of cross-linked urethane resin, resulting in difficulty in forming an IPN structure. Therefore, (meth)acrylic monomers are preferably monomers with a total of two or three acryloyl and methacryloyl groups in one molecule, more preferably bifunctional (meth)acrylic monomers with a total of two such groups. Monofunctional monomers can also be combined as needed.

[0068] The bifunctional (meth)acrylate monomer is preferably at least one selected from the group consisting of alkylene glycol di(meth)acrylates and alkylene glycol di(meth)acrylates with olefinic oxide (ethylene oxide, propylene oxide) modifications. For example, propylene oxide-modified neopentyl glycol diacrylate may be mentioned.

[0069] Examples of trifunctional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate.

[0070] The molecular weight of the (meth)acrylic monomers is preferably in the range of 200 to 750. By using molecular weights within this range, an IPN structure can be easily formed in the network structure of the crosslinked urethane resin, and the strength of the resin layer can be effectively improved.

[0071] The content of cross-linked acrylic resin in the resin layer is preferably 3 to 20 parts by weight, more preferably 5 to 15 parts by weight, relative to 100 parts by weight of cross-linked urethane resin.

[0072] As described above, (meth)acrylic acid monomers are impregnated into a resin layer comprising a crosslinked urethane resin. For this purpose, the (meth)acrylic acid monomers have suitable viscosity. That is, impregnation is difficult at high viscosity, and controlling the impregnation state is difficult at low viscosity. Therefore, the viscosity of the (meth)acrylic acid monomers at 25°C is preferably 5.0 mPa·s to 140 mPa·s. Specifically, one or more (meth)acrylic acid monomers satisfying the above molecular weight and viscosity ranges are selected, impregnated into the resin layer, and polymerized to form an IPN structure of crosslinked urethane resin and crosslinked acrylic resin.

[0073] There are no particular restrictions on the polymerization methods for (meth)acrylic acid monomers; known methods can be used. Specifically, methods such as heating and ultraviolet irradiation can be mentioned. For each polymerization method, known free radical polymerization initiators and ionic polymerization initiators can be used. These polymerization initiators can be used alone or in combination of two or more.

[0074] Known heating devices and ultraviolet irradiation devices can be used appropriately. For example, LED lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and low-pressure mercury lamps can be used as light sources for ultraviolet irradiation. The cumulative light intensity required for polymerization can be appropriately adjusted according to the compounds used and the type and amount of polymerization initiator added.

[0075] Surface modifier

[0076] In addition to the crosslinked urethane resin, the resin layer may also contain surfactants such as modified organosilicon compounds and modified fluorine compounds. The surfactants may have both low-polarity and high-polarity groups, such as silicone-containing groups or fluorine-containing groups, at the modification sites. Preferably, a surface modifier is included in the urethane raw material mixture that forms the crosslinked urethane resin.

[0077] Because of the significant polarity difference between the urethane groups or other highly polar groups in the crosslinked urethane resin and the low polarity groups, such as siloxane groups or fluorine groups, in the surfactant molecule, the surfactant migrates and remains near the outer surface of the resin layer. Furthermore, when (meth)acrylic monomers and polymerization initiators swell from the outer surface of the crosslinked urethane resin containing the surfactant, the (meth)acrylic monomers remain near the surfactant where the polarity difference between the (meth)acrylic monomers and the highly polar groups in the surfactant molecule is small. In other words, because the (meth)acrylic monomers cure while remaining near the outer surface, it becomes easier to locally form IPN structures on and near the outer surface of the resin layer.

[0078] carbon black

[0079] The resin layer comprises a binder resin and carbon black dispersed in the binder resin. The carbon black is dispersed in the resin layer to obtain electrical conductivity. Furthermore, to promote higher dispersion in the resin layer, carbon black with a primary particle number average diameter of 30 nm or less, a DBP absorption of 90 mL / 100 g or less, and a pH of 4.0 or less is preferred.

[0080] When the number average diameter of the primary carbon black particles is less than 30 nm and the DBP absorption is less than 90 mL / 100 g, the aggregates (primary aggregates) that are the smallest dispersible units of carbon black become smaller, and the structure (the size of the particle connections) also becomes smaller, making it easier to reduce the spherical equivalent diameter Rc, which will be described later.

[0081] A lower number-average diameter is preferred, and there is no specific lower limit. For example, the number-average diameter of the primary particles of carbon black is 5 nm to 30 nm, more preferably 20 nm to 30 nm. The primary particle size of carbon black can be calculated using transmission electron microscopy (TEM).

[0082] Lower DBP absorption is preferred, and there is no specific lower limit. For example, the DBP absorption of carbon black is more preferably 30–90 mL / 100 g and 40–80 mL / 100 g.

[0083] When the pH of carbon black is below 4.0, the repulsion of functional groups on the surface of the carbon black makes it difficult for the carbon black to aggregate. Therefore, the effect of dispersion stability is obtained. A lower pH of carbon black is preferred, and there is no specific lower limit. For example, the pH of carbon black is more preferably 2.0 to 4.0 and 2.2 to 3.6.

[0084] However, even if the number-average diameter of the primary particles, DBP absorption, and pH of the carbon black are within the aforementioned ranges, the carbon black may not be sufficiently dispersed when using polycarbonate urethane as a binder resin, and the desired dispersion state may not be achieved. The reason why carbon black with the desired raw material properties cannot be dispersed when using polycarbonate urethane as a binder resin is unclear, but it is speculated to be as follows.

[0085] The hydroxyl groups on the surface of carbon black readily interact with the terminal hydroxyl groups of polycarbonate diol. Meanwhile, the structure present between the two hydroxyl groups of polycarbonate diol, where the carbonate bond and hydrocarbon group are bonded to each other, is hydrophobic due to the presence of the hydrocarbon group and does not readily interact with carbon black. A structure with near-hydrophobicity and near-hydrophilicity is structurally more stable; therefore, hydrophilic carbon black exists near also hydrophilic carbon black. As a result, carbon black is likely to aggregate and is difficult to disperse.

[0086] In order to ensure that carbon black with primary particle number average diameter, DBP absorption and pH within the above-mentioned range is sufficiently dispersed when using polycarbonate urethane as a binder resin, the following additives are more preferably added.

[0087] Considering the reinforcing properties and conductivity of the resin layer, the carbon black content is preferably 5 to 45 parts by mass relative to 100 parts by mass of the binder resin forming the resin layer, more preferably 20 to 40 parts by mass. When the content exceeds 45 parts by mass, the distance between carbon black particles in the coating material liquid is appropriately maintained, the probability of collision due to the Brownian motion of the carbon black is reduced, and the carbon black is less likely to aggregate. Therefore, the carbon black is easily dispersed, and the dispersion stability is improved. As a result, the carbon black is well dispersed in the resin layer formed by the coating material liquid.

[0088] The arithmetic mean Rc of the equivalent circular diameter of the carbon black in the resin layer needs to be 80 nm or less, and the arithmetic mean d of the distance between the walls of the carbon black in the resin layer needs to be 60 nm to 170 nm. Furthermore, it is preferable that the arithmetic mean Rc of the equivalent circular diameter is 60 nm or less. Even more preferably, it is preferable that the arithmetic mean d of the distance between the walls is 80 nm to 150 nm.

[0089] When using the numerical ranges for the equivalent diameter of the circle and the distance between the walls as described above, in low-temperature environments, scratches are unlikely to propagate into the interior of the resin layer with the IPN structure, and crack formation can be suppressed. When the arithmetic mean of the equivalent diameter, Rc, exceeds 80 nm, scratches are likely to propagate along the resin-carbon black interface, and when the arithmetic mean of the distance between the walls, d, is less than 60 nm, adjacent carbon black particles are likely to be in close contact with each other, and scratches are likely to propagate. Furthermore, when d exceeds 170 nm, it is difficult to obtain adequate conductivity.

[0090] When the standard deviation of the equivalent diameter of a circle is expressed as σc, σc / Rc is, for example, 0.000 to 0.730, preferably 0.000 to 0.650, and more preferably 0.500 to 0.650.

[0091] The arithmetic mean Rc and standard deviation σc of the equivalent diameter of a circle can be altered, for example, by the dispersion state in a grinding mill or similar equipment during the preparation of the resin coating material. Weaker dispersion tends to increase Rc and σc, while stronger dispersion tends to decrease them. Typically, Rc converges, so once a certain dispersion state is exceeded, σc can be decreased while Rc remains almost constant, and thus the σc / Rc ratio can be reduced.

[0092] When the standard deviation of the distance between the walls is expressed as σd, σd / d is, for example, 0.000 to 0.680, preferably 0.000 to 0.600, and more preferably 0.500 to 0.600.

[0093] By keeping σc / Rc and σd / d within the above ranges, scratches and cracks can be suppressed more easily.

[0094] The arithmetic mean d and standard deviation σd of the distance between the walls can be altered, for example, during the preparation of the resin coating material by the dispersion state in a grinding mill or similar equipment. Weaker dispersion tends to decrease d and increase σd, while stronger dispersion tends to increase d and decrease σd. Therefore, weaker dispersion tends to increase σd / d, and stronger dispersion tends to decrease σd / d.

[0095] Multiple types of carbon black can be used in combination, as long as the dispersion state of the carbon black meets the above requirements.

[0096] resin particles

[0097] To form protrusions on the surface of the electrophotographic roller, resin particles can be incorporated into the resin layer. When the resin layer has a surface roughness, it may contain fine particles to impart roughness to the resin layer. Specifically, fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, and polycarbonate resin can be used. These are also preferably cross-linked resin particles.

[0098] When an IPN structure is formed on the outer surface of the resin layer, an IPN structure can also be formed inside the cross-linked resin particles. The volume average particle size of the fine particles is preferably 1.0 μm to 30 μm. The surface roughness (ten-point average roughness) Rzjis formed by the fine particles is preferably 0.1 μm to 20 μm. Rzjis is a value measured based on JIS B0601 (1994).

[0099] additive

[0100] Additives are preferably used to further improve the dispersibility of carbon black in the binder resin of polycarbonate urethane. Additives make it easier to set Rc, d, σc / Rc, and σd / d within the aforementioned ranges. Here, as an additive, the resin layer preferably contains at least one compound selected from the group consisting of a compound having a structure represented by the following structural formula (2), a compound having a structure represented by the following structural formula (3), and a compound having a structure represented by the following structural formula (4). One method of incorporating the additive into the resin layer is to include a dispersant in the resin layer coating material. In a resin layer formed using a resin layer coating material containing at least one compound selected from the group consisting of a compound having a structure represented by the following structural formula (2) and a compound having a structure represented by the following structural formula (3), the compound can be incorporated into the ends of the polyurethane polymer chains. Even in such cases, an effect of improved carbon black dispersibility can be expected, but it is preferable that the additive exists in the resin layer independently of the polyurethane.

[0101] Of these, structural formula (2) is preferred because it allows for particularly excellent carbon black dispersion and affinity with polycarbonate and urethane. By satisfying the above conditions, it becomes easier to achieve the aforementioned carbon black dispersion state, and it also becomes easier to set Rc, d, σc / Rc, and σd / d within the aforementioned ranges.

[0102]

[0103] In structural formula (2), R21 represents a monovalent hydrocarbon group with 1 to 12 carbon atoms (preferably 3 to 12). t and u are the average number of moles added, each independently representing a number of 1 or more (preferably 5 to 30, more preferably 10 to 25).

[0104] In structural formula (3), R31 represents a monovalent hydrocarbon group with 1 to 8 carbon atoms (preferably 1 to 4). v and w represent the average number of moles of addition, each independently representing a number of 1 or more (preferably 1 to 30, more preferably 5 to 30).

[0105] In structural formula (4), R41 represents a monovalent hydrocarbon group with 1 to 12 carbon atoms. x is the average number of moles added, and x represents a number greater than 1 (preferably 1 to 30, more preferably 4 to 15).

[0106] Structural formula (2) is a polyoxyethylene polyoxypropylene alkyl ether, a block-structured polyether monool obtained through the addition polymerization of ethylene oxide and propylene oxide. The terminal hydroxyl groups of this polyether monool interact with the surface functional groups of carbon black, which serves as a conductive filler, via hydrogen bonds, thus acting as a dispersant for the carbon black. Furthermore, the obtained structure exhibits good compatibility with polycarbonate and urethane, thereby enhancing the effect of carbon black as a dispersant.

[0107] Ethylene oxide is introduced into the structure to ensure the additive is uniformly distributed within the polycarbonate urethane. This is believed to be because the ethylene in ethylene oxide has good compatibility with the hydrophobic hydrocarbon groups in polycarbonate urethane. Additionally, propylene oxide is introduced into the structure to improve the dispersibility of carbon black dispersed in the resin layer. This is believed to be because the side-chain methyl groups of propylene oxide interact with carbon black, improving its dispersibility.

[0108] The introduction of R21, a monovalent hydrocarbon group with 1 to 12 carbon atoms, into the structure ensures the uniform presence of the additive within the polycarbonate urethane. This monovalent hydrocarbon group exhibits good compatibility with the hydrophobic hydrocarbon groups in the polycarbonate urethane and further ensures the uniform presence of the additive within the polycarbonate urethane. Since the number of carbon atoms is less than 12, steric hindrance with the polycarbonate urethane is unlikely, making it easier for the additive to exist uniformly.

[0109] Since the compound of structural formula (2) has a monool structure, it is less reactive than a diol and is unlikely to participate in the carbamate reaction caused by the reaction of isocyanate with polyol.

[0110] Polyoxyethylene polyoxypropylene alkyl ethers can be commercially available products or can be synthesized. The synthesis of polyoxyethylene polyoxypropylene alkyl ethers can be carried out by step (B) following step (A). Step (B) can also be performed on commercially available products having the structure obtained by completing step (A).

[0111] Step (A): Reaction of alcohol with ethylene oxide.

[0112] Step (B): React the product obtained in step (A) with propylene oxide.

[0113] Step (A) can be carried out by adding ethylene oxide to an alcohol at 50°C to 200°C, more preferably 100°C to 160°C, in the presence of a catalyst. Since ethylene oxide has a boiling point of 10.7°C and is a gas at the above temperatures, it is preferable to carry out the reaction under pressure in a sealed container. The pressure is preferably 0.1 MPa to 1.0 MPa. The reaction time is not particularly limited, but to reduce the amount of unreacted ethylene oxide, it is preferably about 1 hour to 3 hours.

[0114] Both acid and base catalysts can be used as catalysts, but base catalysts are preferred for ease of purification after the reaction. Examples of base catalysts include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, ammonium hydroxide, and tertiary amines. Sodium hydroxide and potassium hydroxide are particularly preferred considering the ease and efficiency of the reaction. Examples of acid catalysts include Brønsted acids such as sulfuric acid and phosphoric acid, and Lewis acids such as tin chloride and boron trifluoride.

[0115] For sodium hydroxide and potassium hydroxide, the catalyst is preferably used at an amount of 0.1 mol% to 5 mol% per mol of alcohol. Since ethylene oxide reacts with water to produce ethylene glycol, it is important to prevent moisture from entering the reaction system, and if necessary, dehydration treatment can be performed before the reaction in step (A).

[0116] Step (B) can be carried out under the same conditions as step (A). Since propylene oxide has a boiling point of 34.2°C and is a gas at reaction temperatures of 50°C to 200°C, it is preferable to carry out the reaction under pressure in a sealed container. As a catalyst, the catalyst used in step (A) can be used as is, or a new catalyst can be added. If a new catalyst is added, the catalyst used in step (A) is preferred.

[0117] Structural formula (3) is a polyetheramine (monoamine) having a block addition polymerization structure in which ethylene oxide and propylene oxide are polymerized. The amino group at the end of this polyetheramine interacts with the surface functional groups of carbon black, which is a conductive filler, through hydrogen bonding, thus acting as a dispersant for carbon black. In addition, to enhance its effect as a dispersant, R31, a monovalent hydrocarbon group with 1 to 8 carbon atoms, is introduced to obtain a structure that is likely to have affinity for the hydrophobic functional groups of polycarbonate urethane and also has good compatibility with polycarbonate urethane.

[0118] Polyether monoamines can be commercially available or synthesized. The synthesis of polyether monoamines can be carried out by performing the following step (C), followed by step (D).

[0119] Step (C): Oxidation reaction of the compound with structural formula (2) as a secondary alcohol.

[0120] Step (D): Reductive amination of the product obtained in step (C).

[0121] Step (C) is the reaction to produce a ketone by oxidation of a secondary alcohol. The synthesis of a ketone by oxidation of a secondary alcohol can be carried out by oxidation reactions using heavy metal salts and their derivatives such as chromic acid and manganese dioxide, or by oxidation reactions using non-heavy metal salts such as dimethyl sulfoxide (DMSO) and hypohalous acids such as hypochlorous acid.

[0122] Either method can be used for synthesis, but considering the environmental impact of heavy metals, the oxidation reaction of dimethyl sulfoxide (DMSO) and a hypohalous acid such as hypochlorous acid is preferred. Furthermore, DMSO reacts explosively at room temperature depending on the electrophilic activating agent used, thus requiring a low temperature of -60°C, making the method using hypohalous acids more preferable. Examples of hypohalous acids include hypochlorites such as sodium hypochlorite and calcium hypochlorite (bleaching powder). Ketones are obtained by reacting these hypochlorites with secondary alcohols in acetic acid.

[0123] When using dimethyl sulfoxide (DMSO), an electrophilic activator is also required. The electrophilic activator increases the electrophilicity of the sulfur in the DMSO, which then undergoes a nucleophilic attack by the alcohol's hydroxyl group. This nucleophilic attack produces a dimethylalkoxysulfonium salt, which then decomposes to produce a ketone and a dimethyl sulfide. Examples of electrophilic activators include dicyclohexylcarbodiimide (DCC), acetic anhydride, phosphorus pentoxide, sulfur trisulfide-pyridine complexes, trifluoroacetic anhydride, oxalyl chloride, and halogens.

[0124] Step (D) is a reductive amination reaction that converts a ketone to an amine. The reaction is divided into two stages. First, the carbonyl group reacts with the amine to generate an imine cation. Next, the hydride reducing agent attacks the imine cation with nucleophilic attack to generate an amine. Borohydride reagents are preferably used as reducing agents. Examples of borohydride reagents include sodium cyanoborohydride, sodium triacetoxyborohydride, and 2-methylpyridine-borane. Among these, sodium triacetoxyborohydride and 2-methylpyridine-borane are preferred due to their low toxicity. In reductive amination reactions using borohydride reagents, the reagents have a large volume structure, and the steric hindrance makes it difficult to generate an imine cation. Therefore, it is preferred that R31 in structural formula (3) is a monovalent hydrocarbon group with 1 to 8 carbon atoms.

[0125] Structural formula (4) is polyoxyethylene alkyl ether acetic acid. The terminal carboxylic acid in structural formula (4) interacts with the surface functional groups of carbon black, which is a conductive filler, through hydrogen bonds, and acts as a dispersant for carbon black. In addition, in order to enhance its effect as a dispersant, a monovalent hydrocarbon group with 1 to 12 carbon atoms as R41 is introduced to obtain a structure that is likely to have affinity for the hydrophobic functional groups of polycarbonate urethane and good compatibility with polycarbonate urethane.

[0126] Polyoxyethylene alkyl ether acetic acid can be commercially available or synthesized. The synthesis of polyoxyethylene alkyl ether acetic acid can be carried out by step (F) following step (E). Step (F) can also be performed on commercially available products having the structure obtained by completing step (E).

[0127] Step (E): The reaction of alcohol with ethylene oxide.

[0128] Step (F): Oxidation of the primary alcohol as a product of step (E).

[0129] Step (E) is the same as step (A), and its product can be manufactured in the same manner as in step (A).

[0130] In step (F), the primary alcohol is oxidized to produce a carboxylic acid. Since the oxidation of the primary alcohol produces an aldehyde, and subsequent oxidation produces a carboxylic acid, the reaction method and conditions must be chosen so that the reaction does not stop at the aldehyde. Examples of methods for obtaining carboxylic acids by oxidation of primary alcohols include oxidation using oxidants and catalytic dehydrogenation using catalysts. Examples of oxidants include permanganates, chromic acid, ruthenium tetroxide, and hypochlorites. Examples of catalysts used for dehydrogenation reactions include palladium, platinum, iridium, rhodium, and manganese.

[0131] Compounds represented by structural formulas (2) to (4) function as dispersants for carbon black and have a high affinity for polycarbonate and urethane. Surfactants are typically used to improve the dispersibility and dispersion stability of carbon black. However, compounds represented by structural formulas (2) to (4) have only a small number of functional groups that act on the surface functional groups of carbon black, thus exhibiting a weak surfactant effect and are generally not used. Coupling agents and nonionic surfactants are commonly used as dispersants for carbon black.

[0132] Silane coupling agents, titanate coupling agents, and aluminum coupling agents can be used as coupling agents, while polyester surfactants and polyether surfactants can be used as nonionic surfactants. However, adding these dispersants at a level sufficient to improve the dispersibility of carbon black in polycarbonate urethane (50% to 100% by mass relative to carbon black) hinders the conductivity of both carbon black and binder resins. Conversely, when the dispersant is added in an amount that does not hinder the conductivity of both carbon black and binder resins (10% to 40% by mass relative to carbon black), good dispersibility of carbon black cannot be obtained.

[0133] The amount of the compound represented by structural formulas (2) to (4) added is preferably within the following range. The content of the compound represented by structural formulas (2) to (4) in the resin layer is preferably 3.0% to 7.0% by mass. In addition, this content is preferably 18.9 to 46.0 parts by mass relative to 100 parts by mass of carbon black.

[0134] When the addition amount is equal to or higher than the lower limit, the dispersibility of carbon black is improved, and the desired dispersibility is more easily achieved. When the addition amount is equal to or lower than the upper limit, it is less likely to hinder the urethane polymerization reaction, and the desired hardness and electrical resistance are more easily obtained.

[0135] The presence of additives in the resin layer can be confirmed and quantitatively evaluated using the following methods: Cut out the resin layer of the electrophotographic roller and use, for example...1 H-NMR, 13 C-NMR, XPS, and FT-IR analysis of the sections. This allows for the detection of the carbonate structure of the binder resin in the resin layer, as well as the ether, amine, and carboxylic acid structures of the additives, and their proportions can be calculated from peak ratios, etc.

[0136] Alternatively, the slices can be soaked overnight in an organic solvent such as methyl ethyl ketone for extraction, and the extract and the extracted slices can be treated with... 1 H-NMR, 13 The analysis was performed using C-NMR, XPS, and FT-IR. Therefore, the proportions of additives incorporated and not incorporated during the resin polymerization reaction can be calculated.

[0137] The resin layer may have a structure in which at least one of the compounds having the structures shown in structural formulas (2) and (3) is bonded to polyurethane (a structure obtained by the reaction during polyurethane polymerization). For example, the structure obtained by the reaction during polyurethane polymerization may be in the following form:

[0138] - In the case of the structure shown by structural formula (2), the structure obtained in polyurethane by urethane esterification of a compound having the structure shown by structural formula (2).

[0139] - In the case of the structure shown by structural formula (3), the structure obtained in polyurethane by urethane esterification of a compound having the structure shown by structural formula (3).

[0140] Other additives

[0141] In addition to the above, the resin layer may also contain various additives such as crosslinking agents, crosslinking aids, plasticizers, fillers, extenders, vulcanizing agents, vulcanizing aids, antioxidants, anti-aging agents, processing aids, dispersants, and leveling agents, as long as these additives do not impair the above functions.

[0142] Manufacturing method

[0143] Method for manufacturing resin layer

[0144] The manufacturing method of an electrophotographic roller preferably includes the steps of preparing a conductive substrate and forming a resin layer on the outer peripheral surface of the substrate. The resin layer forming step preferably includes obtaining a cross-linked urethane resin by applying a mixture of urethane raw materials (resin layer coating material) comprising a urethane raw material for forming a cross-linked urethane resin and a surface modifier, and then curing it. Alternatively, it is preferable to impregnate the cross-linked urethane resin with a (meth)acrylate monomer for forming a cross-linked acrylic resin, polymerize the (meth)acrylate monomer, and form a cross-linked acrylic resin to obtain the resin layer.

[0145] Prior to the resin layer formation step, an elastic layer can be formed on the outer surface of the substrate. The elastic layer can be obtained, for example, by applying a silicone rubber mixture to the outer surface of the substrate and curing it.

[0146] There are no particular limitations on the method for forming a resin layer comprising a cross-linked urethane resin, but a coating method using a liquid coating material is preferred. For example, it is preferable to disperse and mix the resin layer in a solvent to form a urethane raw material mixture in the coating material, then coat it onto a conductive substrate and dry it to solidify or cure it by heating.

[0147] From the viewpoint of compatibility with polyols and isocyanate compounds that are raw materials for crosslinking urethane resins, polar solvents are preferred as solvents.

[0148] Examples of polar solvents include alcohols such as methanol, ethanol, and n-propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate. One or more of these solvents that are compatible with other materials can be used in combination.

[0149] The solid content of the coating material can be freely adjusted by the amount of solvent mixed in, but from the viewpoint of uniformly dispersing electronically conductive materials such as carbon black (described later), a solid content of 20% to 40% by mass is preferred. For dispersion and mixing, known dispersion devices using beads can be used, such as sand mills, paint mixers, dynomills, and pearl mills. For coating, dip coating, ring coating, spray coating, or roller coating can be used.

[0150] For example, polyols and isocyanate compounds, which serve as raw materials for binder resins, carbon black, surface modifiers, additives, etc., are mixed to obtain a liquid coating material. The resin coating material is then applied to a substrate. Subsequently, the resin layer is dried and solidified or cured by heating to form a cross-linked urethane resin.

[0151] Next, the resin layer formed as described above is impregnated with a liquid (meth)acrylic acid monomer. The liquid (meth)acrylic acid monomer can be impregnated as is or as an impregnation treatment solution obtained by appropriate dilution with various solvents. By appropriately diluting the liquid (meth)acrylic acid monomer with various solvents, a resin layer with a more uniform surface composition can be obtained.

[0152] Solvents can be freely chosen, as long as they satisfy both affinity for the resin layer and the ability to dissolve (meth)acrylic acid monomers. Examples include alcohols such as methanol, ethanol, and n-propanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate.

[0153] In addition, a polymerization initiator is appropriately mixed into the impregnation treatment solution. Details of the polymerization initiator are as described above. There are no particular limitations on the impregnation method using the impregnation treatment solution; dip coating, ring coating, spray coating, or roller coating can be used. Afterward, the resin layer is dried, for example, at 80°C to 120°C for 0.5 hours to 3 hours to allow the solvent to evaporate.

[0154] This process allows cross-linked (meth)acrylic resins to be introduced into the network structure of cross-linked urethane resins in an intertwined manner, forming an IPN structure. In particular, it is preferable to form an IPN structure with cross-linked polymers having an elastic modulus higher than that of the cross-linked urethane resins, especially with cross-linked (meth)acrylic resins.

[0155] This IPN structure is formed by impregnating a cross-linked urethane resin as a first component with (meth)acrylic monomers and a polymerization initiator from the outer surface, and then forming a cross-linked acrylic resin as a second component. In this case, the (meth)acrylic monomers permeate between the three-dimensional network structure of the cross-linked urethane resin and polymerize to form a cross-linked acrylic resin network structure.

[0156] The thickness of the resin layer is 2.0 μm to 30.0 μm, preferably 5.0 μm to 30.0 μm, and more preferably 10.0 μm to 20.0 μm.

[0157] Processing box and electrophotographic image forming equipment

[0158] Electrophotographic image forming equipment includes an electrophotographic roller.

[0159] The electrophotographic image forming apparatus disclosed herein includes an image carrier member for carrying an electrostatic latent image, a charging roller for energizing the image carrier member once, and a developing roller for developing the electrostatic latent image with a toner to form a toner image.

[0160] Electrophotographic image forming apparatus may include an image carrier member for carrying an electrostatic latent image, a charging roller for energizing the image carrier member once, an exposure device for forming an electrostatic latent image on the once-energized image carrier member, a developing roller for developing the electrostatic latent image with a toner to form a toner image, and a transfer device for transferring the toner image to a transfer material.

[0161] Preferably, either or both of the charging roller and the developing roller are the electrophotographic rollers of this disclosure.

[0162] Figure 3 This is a cross-sectional view showing the outline of an electrophotographic image forming apparatus according to one embodiment of the present disclosure. Figure 4 It is to be installed Figure 3 An enlarged cross-sectional view of a processing cartridge 22 in an electrophotographic image forming apparatus. The processing cartridge 22 includes an image-carrying member 19, a charging device including a charging roller 20, and a developing device including a developing roller 15. The processing cartridge may have a cleaning device including a cleaning member 21. The processing cartridge includes an electrophotographic roller. Preferably, either or both of the charging roller and the developing roller are electrophotographic rollers of this disclosure. The processing cartridge is configured to be detachably mounted to... Figure 3 The main body of the electronic photographic image forming device.

[0163] The image carrier member 19 is uniformly charged (primarily charged) by a charging roller 20 connected to a bias power supply (not shown). At this point, the charging potential of the image carrier member 19 is -800V to -400V. Next, the image carrier member 19 is irradiated with exposure light 23 by an exposure device (not shown) for writing an electrostatic latent image, which is formed on the surface of the image carrier member. LED light or a laser can be used as the exposure light 23. The surface potential of the exposed portion of the image carrier member 19 is -200V to -100V.

[0164] Next, the developing roller 15 applies negatively charged toner 31 to the electrostatic latent image (developing process), forming a toner image on the image carrier member 19 and converting the electrostatic latent image into a visible image. At this time, a voltage of -500V to -300V is applied to the developing roller 15 through a bias power supply (not shown). The developing roller 15 contacts the image carrier member 19 with a gap width of 0.5mm to 3mm.

[0165] In a processing cassette according to one embodiment of the present disclosure, the toner supply roller 17 is rotatably positioned upstream of the developing roller 15 on the side of the developing blade 16, which serves as a toner layer thickness control member, and the developing roller 15, so that the toner supply roller 17 contacts the developing roller 15. The toner image developed on the image carrier member 19 is transferred once to the intermediate transfer belt 24. The primary transfer member 25 contacts the back side of the intermediate transfer belt 24, and a voltage of +100V to +1500V is applied to the primary transfer member 25 to perform a primary transfer of the negative polarity toner image from the image carrier member 19 to the intermediate transfer belt 24. The primary transfer member 25 may be in the form of a roller or a blade.

[0166] When the electrophotographic image forming apparatus is a panchromatic image forming apparatus, the above-described charging, exposure, development, and single transfer steps are performed for each of the following colors: yellow, cyan, magenta, and black. Therefore, in Figure 3In the electrophotographic image forming apparatus shown, a total of four processing cartridges, each containing a toner of each color, are detachably mounted to the main body of the electrophotographic image forming apparatus. The above-described charging, exposure, development, and single transfer steps are performed sequentially with a predetermined time difference, and an image of the four colors of toner is created by superimposing them on the intermediate transfer belt 24 to represent a full-color image.

[0167] As the intermediate transfer belt 24 rotates, the toner image on the intermediate transfer belt 24 is conveyed to a position facing the secondary transfer member 26. Between the intermediate transfer belt 24 and the secondary transfer member 26, recording paper is conveyed along the recording paper transport path 27 at predetermined times, and the toner image on the intermediate transfer belt 24 is transferred to the recording paper by applying a secondary transfer bias voltage to the secondary transfer member 26. At this time, the bias voltage applied to the secondary transfer member 26 is +1000V to +4000V.

[0168] Recording paper, with the toner image transferred via secondary transfer member 26, is fed to fixing unit 28, where the toner image on the recording paper melts and is fixed onto the recording paper. The recording paper is then ejected from the electrophotographic image forming apparatus, completing the printing operation. Any toner remaining on image carrier 19 that was not transferred from image carrier 19 to intermediate transfer belt 24 is scraped off by cleaning member 21, which cleans the surface of image carrier 19.

[0169] Method for determining the elastic modulus of SPM

[0170] First, while maintaining the temperature at -110°C, a cross-sectional area including the resin layer of the electrophotographic roller was cut using a diamond blade on a cryostat (product name: EMFC6, manufactured by Leica Microsystems). Furthermore, a 100μm square sample with a width of 100μm in the depth direction was prepared from the slice.

[0171] Figure 5 A schematic cross-sectional view is shown of a resin layer 54 formed on a conductive substrate 53. In this disclosure, as... Figure 5 As shown, the region extending from the outer surface of the resin layer 54 to a depth of 0.1 μm is defined as the first region 51, and the region extending from the outer surface to a depth of 1.0 μm to 1.1 μm is defined as the second region 52.

[0172] The elastic modulus of the binder resin containing cross-linked urethane resin as a binder was determined in each region appearing on the cross-section of the prepared sample. For the determination, an SPM apparatus (product name: MFP-3D-Origin, manufactured by Oxford Instruments) and a probe (product name: AC160, manufactured by Olympus Corporation) were used. First, a 5 μm square shape image was acquired. Then, force curves were measured 10 times at the locations of the binder resin excluding rough forming particles and carbon black, and the arithmetic mean of 8 points excluding maximum and minimum values ​​was obtained. The elastic modulus was calculated using Hertzian theory. The elastic moduli of the binder resin in the first region 51 and the second region 52 were defined as E1 and E2, respectively.

[0173] The meaning of E1 in the first region is as explained in the above-mentioned <Technical significance of claim (1)>. E2 in the second region is the elastic modulus in the region from the outer surface to a depth of 1.0 μm to 1.1 μm. That is, the elastic modulus of the adhesive resin in the second region from the outer surface of the resin layer to a depth of 1.0 to 1.1 μm, measured in a cross section in the thickness direction of the resin layer, is taken as E2. In this case, the elastic modulus E2 is, for example, 120 MPa to 250 MPa, preferably 120 MPa to 200 MPa, and more preferably 140 MPa to 190 MPa.

[0174] When E2 in the second region is within the aforementioned range, the load when the electrophotographic roller comes into contact with the toner is reduced, and film formation occurring when the toner is physically broken down can be suppressed. In this disclosure, it is more preferable to simultaneously satisfy E1, E2, and high dispersion of carbon black. By simultaneously satisfying the ranges of the arithmetic mean Rc of the equivalent diameter of E1, E2, and carbon black, and the arithmetic mean d of the distance between the walls, film formation, scratches caused by grinding, and cracks caused by the propagation of scratches can be simultaneously suppressed, and the durability of the electrophotographic roller can be significantly improved. An IPN structure is preferably used as a method to increase the elastic modulus E1, and E1 can be selectively increased without increasing E2. Therefore, the second region does not need to have an IPN structure.

[0175] One way to increase E1 is, for example, to significantly increase the crosslinking density of the rubber constituting the surface of the electrophotographic roller. However, in this case, the hardness is likely to increase even into the interior of the resin layer. By setting the elastic modulus E2 within the aforementioned range, scratches and film formation can be more easily suppressed.

[0176] Methods for confirming the structure of interpenetrating polymer networks (IPNs)

[0177] The IPN structure was verified using micro-sampling mass spectrometry. An ion trap mass spectrometer was used for micro-sampling mass spectrometry. The sample was fixed to a filament at the tip of the probe and directly inserted into the ionization chamber. The sample was then rapidly heated from room temperature to 1000°C at a constant heating rate. The sample, which decomposed and evaporated by heating, was ionized by electron beam irradiation and then detected by the mass spectrometer.

[0178] At this point, under constant heating rate conditions, a thermochromatogram similar to TG-MS (thermogravimetric-mass simultaneous analysis) is obtained, which has a mass spectrum called total ion chromatogram (TIC). Furthermore, thermochromatograms of fragments with predetermined masses can be obtained, thus allowing the acquisition of the peak temperature of the thermochromatogram corresponding to the decomposition temperature of the desired molecular structure. The peak temperature of the thermochromatogram is related to the cross-linking structure in the resin structure; the denser the cross-linking, the higher the peak temperature. In other words, compared to a single cross-linked (meth)acrylic resin, the peak temperature of the thermochromatogram will be higher in the portion where the cross-linked urethane resin and the cross-linked (meth)acrylic resin form an IPN structure.

[0179] The peak temperature A1 of the thermochromatogram derived from the crosslinked acrylic resin was obtained from a first sample obtained from a first region, which extends from the outer surface of the resin layer to a depth of 0.1 μm. Furthermore, the peak temperature A2 of the thermochromatogram derived from the crosslinked acrylic resin was obtained from a second sample obtained by decomposing the crosslinked urethane resin contained in the first sample. In the case of an IPN structure, A1 will be higher than A2 in terms of the peak temperature of the thermochromatogram.

[0180] A2 is a value obtained by micro-sampling mass spectrometry analysis of a second sample obtained after decomposing the cross-linked urethane ester by the pyridine decomposition method described below.

[0181] Pyridine decomposition method

[0182] Pyridine decomposition is a method for selectively breaking down urethane bonds. By performing pyridine decomposition on samples containing cross-linked acrylic resins and cross-linked urethane resins with IPN structures, cross-linked acrylic resins can be obtained after removing structures derived from the cross-linked urethane. The presence or absence of an IPN structure can be confirmed by capturing the change in peak temperature of the thermochromatogram of the cross-linked acrylic resin. Specifically, the pyridine decomposition method is performed as follows.

[0183] Using a slicer, a sample was cut from the outer surface of the resin layer of the electron imaging roller at a thickness of 0.1 μm, and 500 mg of sample was collected. 0.5 mL of a mixture of pyridine (manufactured by Wako Pure Chemical Industries, Ltd.) and water in a 3:1 ratio was added to the obtained sample, and the sample was decomposed by heating at 130 °C for 15 hours in a sealed container made of fluoropolymer (“Teflon”, a registered trademark) and equipped with a stainless steel jacket. The pyridine was removed by subjecting the resulting decomposition products to reduced pressure. The sample obtained was then used to perform the micro-sampling mass spectrometry method described above, and the A2 value was obtained.

[0184] Calculations of various physical properties of carbon black dispersed in the resin layer, such as equivalent diameter and distance between the walls.

[0185] The equivalent diameter of the carbon black dispersed in the resin layer and the distance between the wall surface were determined by the following method.

[0186] First, a slice (0.5 mm to 1.0 mm thick) is cut using a razor to allow observation of a cross-section perpendicular to the length of the electrophotographic roller. In cases where the adhesion between the substrate and the resin layer is high and it is difficult to cut with a razor, the slice is cut along with the substrate using a hacksaw or similar tool, and then the cross-section is set using a FIB (Focused Ion Beam) device.

[0187] Platinum vapor was then deposited onto the slices, and images of the resin layer were captured at 15,000x magnification using a scanning electron microscope (SEM) (product name: JSM-7800F, manufactured by JEOL Ltd.) to obtain cross-sectional images.

[0188] Furthermore, to quantize the cross-sectional image obtained through SEM observation, image processing software (Luzex AP, manufactured by Nireco Corporation) was used to convert the cross-sectional image to 8-bit grayscale, thus obtaining a monochrome image with 256 gray levels. Next, the black and white image was inverted, making the carbon black in the cross-sectional image appear white. Then, a binarization threshold was set for the brightness distribution of the image based on Otsu's discriminant analysis algorithm, thereby obtaining a binarized image in which the carbon black is white and the adhesive resin is black.

[0189] Then, image processing software (product name: Luzex AP, manufactured by Nireco Corporation) was used on the obtained binarized image to calculate the circular equivalent diameter Rc of the whitened carbon black portion and the distance d between adjacent walls. The image area used to calculate the circular equivalent diameter and the distance between adjacent walls was set within 0.075 μm as the actual image size (when there is text describing SEM measurement conditions, etc., the image area is set within 0.075 μm from the beginning of the actual image) to eliminate the uncertainty in the calculated values ​​of carbon black split at the top, bottom, left, and right ends of the image, and the circular equivalent diameter and the distance between adjacent walls of the entire carbon black within the specified image area were calculated.

[0190] Then, for the distribution of the obtained circular equivalent diameter and the distance between adjacent walls, the arithmetic mean and standard deviation are calculated. The number of images used for image analysis is 12 points at 0°, 90°, 180°, and 270° in the circumferential direction, at positions of 1 / 4, 1 / 2, and 3 / 4 of the length from the end of the roller, and at the same positions.

[0191] The number-average diameter of the primary carbon black particles dispersed in the resin was determined using transmission electron microscopy (TEM). First, sectioned samples were prepared. Sectioning can be performed using known methods. For example, the sample can be sectioned using an ion beam or a diamond scalpel. In this disclosure, an ultramicrotome (product name: ULTRACUT-S, manufactured by Leica Microsystems) was used to prepare 40 nm thick sectioned samples for observation.

[0192] Then, a transmission electron microscope (product name: H-7100FA, manufactured by Hitachi High-Technologies Corporation) was used to obtain TEM images under measurement conditions in TE mode and accelerating voltage of 100 kV.

[0193] Image analysis software (product name: WinROOF, manufactured by Mitani Shoji Co., Ltd.) was used to determine the circumference equivalent diameter of 50 primary carbon black particles in the obtained TEM image. The average number of the 50 particles in the TEM image was taken as the number-average diameter of the primary particles.

[0194] Determination of DBP absorption of carbon black

[0195] For carbon black powder, the DBP absorption of carbon black was determined according to Japanese Industrial Standard (JIS) K6217-4.

[0196] Determination of pH of carbon black

[0197] For carbon black powder, the pH of the carbon black is determined according to ASTM D1512.

[0198] Measurement of the thickness of the resin layer in the developing roller

[0199] The thickness of the resin layer is determined by measuring the thickness of the resin portion excluding fine particles in the thickness direction using an optical microscope or electron microscope. Measurements are taken at three locations circumferentially on the developing roller, and for each of these, three locations in the direction perpendicular to the circumferential direction (axial direction), for a total of nine locations. The arithmetic mean of the thicknesses at all measurement locations is taken as the thickness of the resin layer.

[0200] Example

[0201] The present disclosure will be described in more detail below using embodiments, but these embodiments are not intended to limit the present disclosure in any way.

[0202] Example 1

[0203] 1. Preparation of conductive substrate

[0204] A primer (product name: DY35-051, manufactured by Dow Corning Toray Co., Ltd.) was applied to a SUS304 core metal with an outer diameter of 6 mm and a length of 270 mm, and heated at 150°C for 20 minutes. The core metal was then concentrically placed as a substrate within a cylindrical mold with an inner diameter of 12.0 mm.

[0205] As the material for the elastic layer that will become the intermediate layer, an addition-curing liquid silicone rubber mixture obtained by mixing the materials shown in Table 1 below using a mixing machine (product name: Trimix TX-15, manufactured by Inoue Mfg., Inc.) is injected into a mold heated to a temperature of 115°C. After the material is injected, it is heated to 120°C for 10 minutes, cooled to room temperature, and then removed from the mold, thereby obtaining a conductive substrate (elastic roller 1) with a 3.0 mm thick elastic layer formed on the outer periphery of the substrate.

[0206] [Table 1]

[0207]

[0208] 2. Formation of the resin layer

[0209] As a material for the resin layer, the polyol, isocyanate, and additives (excluding carbon black and coarse-forming particles) shown in Table 2 below were stirred and mixed using a disperser. Next, while stirring and mixing with a disperser, the carbon black shown in Table 2 below was added little by little. After the addition was complete, stirring and mixing continued for 30 minutes. Then, the mixture was dissolved in methyl ethyl ketone to achieve a solids concentration of 30% by mass. After further premixing for 1 hour, the mixture was dispersed for 4 hours using a sand mill with glass beads of 1.5 mm particle size. Further, coarse-forming particles were added and dispersed in a sand mill for another 10 minutes to obtain resin layer coating material 1.

[0210] The elastic roller 1 is immersed in the coating material and coated to a resin layer thickness of 15 μm. Then, the roller is heated at 135°C for 60 minutes to dry and cure the coating, thereby forming a cross-linked urethane resin in the resin layer.

[0211] [Table 2]

[0212]

[0213] Then, the impregnation and curing treatment of (meth)acrylic monomers capable of forming crosslinked acrylic resins is carried out by the following method. The materials shown in Table 3 below are dissolved and mixed as the impregnation liquid material for the impregnation treatment. An elastic roller with crosslinked urethane resin formed on it is immersed in the impregnation liquid for 2 seconds to perform the impregnation treatment and impregnate the (meth)acrylic monomer component. Afterwards, the roller is immediately dried at 90°C for 1 hour to allow the solvent to evaporate.

[0214] The dried elastic roller is rotated and irradiated with ultraviolet light until the cumulative light intensity reaches 15,000 mJ / cm. 2 This process cures the (meth)acrylic acid monomers, forming an IPN structure and resulting in a resin layer. A high-pressure mercury lamp (product name: Handy Type UV Curing Device, manufactured by Mario Network Co., Ltd.) is used as the ultraviolet irradiation device.

[0215] [Table 3]

[0216]

[0217] The obtained electrophotographic roller was evaluated as follows.

[0218] Evaluation methods

[0219] Calculation of the equivalent diameter of carbon black dispersed in the resin layer and the distance between the wall surface

[0220] Using the method described above for calculating the equivalent diameter of the carbon black dispersed in the resin layer and the distance between the wall surfaces, σc / Rc and σc / d are calculated, where Rc is the equivalent diameter, d is the distance between the carbon black wall surfaces, σc[nm] is the standard deviation of the equivalent diameter, and σc[nm] is the standard deviation of the distance between the wall surfaces. The results are shown in Table 9.

[0221] Determination of the elastic modulus of SPM

[0222] The elastic moduli E1 and E2 of the first and second regions were calculated using the same method described above for determining the elastic modulus of the SPM. The results are shown in Table 9.

[0223] Durability evaluation

[0224] An electrophotographic roller was installed as a developing roller into a processing cartridge for a color laser printer (product name: HP Color LaserJet Enterprise M652dn, manufactured by Hewlett-Packard Co.), and the processing cartridge was installed into the color laser printer to evaluate the condition of scratches caused by grinding on the surface of the electrophotographic roller. For the evaluation, a processing cartridge for a color laser printer (cyan, product name: HP 656X High Yield Cyan Original LaserJet TonerCartridge, manufactured by Hewlett-Packard Co.) was used. The evaluation procedure is as follows.

[0225] The processing cartridge was placed in a high-temperature, high-humidity environment of 30°C and 95% relative humidity for 16 hours. Then, low-print percentage images of 0.2% were continuously printed on recording paper to evaluate the process under the same conditions with a very high number of prints. However, since toner is consumed during printing, toner was replenished every 50,000 prints, bringing the toner weight in the processing cartridge to 100g.

[0226] After printing 200,000 sheets, the developing roller was removed from the processing cassette, air was blown onto the roller surface to remove toner, and the surface condition was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 9.

[0227] Evaluation Criteria

[0228] Grade "A": It can be confirmed that there are no scratches on the surface caused by grinding.

[0229] Grade "B": Scratches can be identified, but the length of the largest scratch is less than 1mm.

[0230] Grade "C": Scratches larger than 1mm are confirmed.

[0231] Evaluation of crack resistance

[0232] The durable printed electrophotographic roller was aged at a low temperature of 10°C and 15% relative humidity for at least 24 hours, and its surface roughness Ra was measured using the method described later. Next, under the same conditions, a brush made of SUS304 (product name: SUS304 stainless steel brush, manufactured by Taiyo Shokai Co., Ltd.) was placed perpendicularly against the electrophotographic roller and rubbed against the roller 10 times while applying a load of 10N, after which the roller was left to stand for 1 hour. Afterward, under the same conditions, the surface roughness Ra was measured again, and the difference ΔRa between the surface roughness Ra before and after the evaluation was evaluated according to the following criteria. The evaluation results are shown in Table 9.

[0233] Evaluation Criteria

[0234] Grade "A": ΔRa before and after evaluation is less than 0.20μm.

[0235] Grade "B": ΔRa before and after evaluation is greater than 0.20μm and less than 0.40μm.

[0236] Grade "C": ΔRa is greater than 0.40μm before and after evaluation.

[0237] Methods for measuring surface roughness (Ra)

[0238] The surface roughness Ra (JIS B0601) of the electrophotographic roller was measured using a surface roughness meter (product name: Surfcom480A, manufactured by Tokyo Seimitsu Co., Ltd.), and the Ra value was recorded. The measurement conditions were: a stylus with a radius of 2 μm, a pressing pressure of 0.7 mN, a measurement speed of 0.3 mm / s, a measurement magnification of 5000x, a cutoff wavelength of 0.8 mm, and a measurement length of 2.5 mm. The arithmetic mean of nine points at 0°, 120°, and 240° along the circumference at positions of 1 / 4, 1 / 2, and 3 / 4 of the length from the end was used.

[0239] Examples 2, 4-11 and 13-15 and Comparative Examples 1, 4 and 6

[0240] Each resin layer coating material was prepared from the materials shown in Table 7 using the same method as used in Example 1, the impregnation treatment liquid was prepared from the materials shown in Table 8, and each electrophotographic roller was manufactured using the combinations shown in Table 9. The obtained electrophotographic rollers were evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0241] Example 3

[0242] Polyoxyethylene octyl ether acetate: Synthesis of Additive A

[0243] 169.3 g of 1-octanol (prepared by Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were placed together in an autoclave equipped with a stirrer, temperature control device, and automatic feeder, and dehydrated at 110 °C and 1.2 kPa for 30 minutes. After dehydration, the mixture was purged with nitrogen, the temperature was raised to 150 °C, and then 858.0 g of ethylene oxide (15 mol relative to the alcohol) was added. The reaction was carried out at 150 °C for 1 hour to obtain an ethylene oxide adduct with an average addition mole of 15 mol.

[0244] A total of 77.4 g of the obtained ethylene oxide adduct was mixed with 510 mL of 1 mol / L sodium hydroxide aqueous solution, and 71.1 g of potassium permanganate was added and stirred at room temperature for 6 hours. Then, 760 mL of 2-propanol was added and stirred for 1 hour to quench the excess potassium permanganate, and the byproduct manganese oxide was filtered off. The aqueous layer was extracted and purified with dichloromethane to obtain additive A as polyoxyethylene octyl ether acetic acid. The structure and x-value of R41 of additive A are shown in Table 5.

[0245] Except for the use of additive A in the resin coating material, the resin coating material was prepared from the materials shown in Table 7 using the same method as in Example 1, and the impregnation treatment solution was prepared from the materials shown in Table 8. The electrophotographic roller of Example 3 was manufactured using the combination shown in Table 9. The obtained electrophotographic roller was evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0246] Example 12

[0247] Polyetheramine: Synthesis of Additive B

[0248] A stirrer was attached to a three-necked flask, and 1658 g of polyoxyethylene polyoxypropylene octyl ether and 460 mL of acetic acid were added. A total of 600 mL of 2 mol / L sodium hypochlorite aqueous solution was added dropwise over 1 hour. The reaction vessel was placed in an ice bath to cool, and the temperature was adjusted to the range of 15°C–25°C. After the addition was complete, stirring was continued for 1 hour. Dichloromethane was added to the resulting liquid, and the aqueous layer was extracted, post-treated, and purified using a column chromatography to obtain the compound in which the secondary alcohol was ketated.

[0249] The mixture was cooled to 0°C in an ice bath. 250 mL of a methanol-acetic acid mixture (volume ratio 10:1) was added to 41.4 g of the compound obtained by ketalizing the secondary alcohol, along with 2.7 g of 2-methylpyridine-borane. The ice bath was removed, and the mixture was stirred overnight in an open system at room temperature. After concentration, the mixture was cooled to 0°C, and 360 mL of a 35% hydrochloric acid aqueous solution was added. The mixture was stirred at room temperature for 2 hours. An aqueous sodium hydroxide solution was added to make the mixture alkaline, and the aqueous layer was extracted with dichloromethane, post-treated, and purified using a column chromatography to obtain additive B as a polyetheramine. The structure of R31 of additive B and the values ​​of v and w are shown in Table 5.

[0250] Except for the use of additive B in the resin coating material, the resin coating material was prepared from the materials shown in Table 7 using the same method as in Example 1, and the electrophotographic roller of Example 12 was manufactured using the combination shown in Table 9. The obtained electrophotographic roller was evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0251] Example 16: Charging Roller

[0252] Preparation of conductive substrate

[0253] A primer (product name: Metaloc N-33, manufactured by Toyo Kagaku Kenkyusho Co., Ltd.) was applied to a SUS304 core metal with an outer diameter of 6 mm and a length of 252 mm, and then heated at 80°C for 30 minutes, followed by a further heating at 120°C for 1 hour. As a material for the intermediate layer, the materials shown in component 1 of Table 4 below were mixed in a pressure mixer to obtain compound rubber composition A. Further, the materials shown in component 2 of Table 4 were mixed with compound rubber composition A in an open mill to prepare an uncured rubber composition.

[0254] Next, a die with an inner diameter of 16.5 mm is installed into a crosshead extruder equipped with a matrix feeding mechanism and an uncured rubber roller discharge mechanism. The extruder and die (crosshead) are set to 80°C, and the conveying speed of the conductive matrix is ​​adjusted to 60 mm / s. Under these conditions, an uncured rubber composition is fed from the extruder and coated as an elastic layer onto the outer periphery of the conductive matrix within the crosshead. Next, it is placed in a hot air vulcanizing furnace at 170°C and heated for 60 minutes. After cooling, the ends of the elastic layer are cut off and removed, and the surface of the elastic layer is ground with a rotating grinding stone to produce a conductive matrix (elastic roller 2) with a diameter of 8.4 mm at each position from the center to both ends (90 mm axially) and a central diameter of 8.5 mm.

[0255] [Table 4]

[0256]

[0257] In addition to using the elastic roller 2 as the substrate, the resin layer coating material was prepared from the materials shown in Table 7, the impregnation treatment liquid was prepared from the materials shown in Table 8, and the electrophotographic roller of Example 16 was manufactured using the combination shown in Table 9, in the same manner as in Example 1.

[0258] The obtained electrophotographic roller was installed as a charging roller into the processing cartridge of a color laser printer (product name: HP ColorLaserJet Enterprise M652dn, manufactured by Hewlett-Packard Co.), and the processing cartridge was installed into the color laser printer to evaluate the condition of scratches on the surface of the electrophotographic roller caused by grinding. For the evaluation, a processing cartridge for a color laser printer (cyan, product name: HP 656X High Yield Cyan OriginalLaserJet Toner Cartridge, manufactured by Hewlett-Packard Co.) was used. The evaluation procedure is as follows.

[0259] The processing cartridge was placed in a high-temperature and high-humidity environment of 30°C and 95% relative humidity for 16 hours. Low-print percentage images (0.2%) were then continuously printed on recording paper to evaluate performance under the same conditions with a very high number of prints. However, since toner is consumed during printing, toner was replenished every 50,000 prints to ensure the toner weight in the processing cartridge was 100g. After printing 200,000 prints, the charging roller was removed from the processing cartridge, air was blown onto the roller surface to remove excess toner, and evaluation was performed using the same method as in Example 1. The evaluation results are shown in Table 9.

[0260] Comparative Example 2

[0261] Polyetheramine: Synthesis of Additive C

[0262] Additive C, used as a polyetheramine, is obtained by synthesizing polyoxyethylene polyoxypropylene decyl ether, then ketating it via secondary alcohol oxidation, followed by reductive amination.

[0263] Synthesis of polyoxyethylene polyoxypropylene decyl ether

[0264] 205.8 g of 1-decyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were placed together in an autoclave equipped with a stirrer, temperature control device, and automatic feeder, and dehydrated at 110 °C and 1.2 kPa for 30 minutes. After dehydration, the mixture was purged with nitrogen, the temperature was raised to 150 °C, and then 858.0 g of ethylene oxide (15 mol relative to the alcohol) was added. The reaction was carried out at 150 °C for 1 hour to obtain an ethylene oxide adduct with an average addition mole of 15 mol.

[0265] The obtained ethylene oxide adduct was cooled to 130°C, and 1132.6 g of propylene oxide (15 mol relative to the alcohol) was added. After the addition was complete, the reaction was carried out at 130°C for 5 hours to obtain a polyoxyethylene polyoxypropylene decyl ether adduct, which is a block polymer with an average addition of 15 moles of ethylene oxide and 15 moles of propylene oxide.

[0266] The obtained polyoxyethylene polyoxypropylene decyl adduct was cooled to 80°C, and unreacted ethylene oxide and propylene oxide were removed at 2.5 kPa for 30 minutes. Next, 6.0 g of 90% lactic acid was added to an autoclave, stirred at 80°C for 30 minutes, and then extracted to obtain polyoxyethylene polyoxypropylene decyl ether.

[0267] Polyetheramine: Synthesis of Additive C

[0268] A stirrer was attached to a three-necked flask, and 1688 g of polyoxyethylene polyoxypropylene decyl ether and 460 mL of acetic acid were added. A total of 600 mL of 2 mol / L sodium hypochlorite aqueous solution was added dropwise over 1 hour. The reaction vessel was placed in an ice bath to cool the mixture, maintaining the temperature between 15°C and 25°C. After the addition was complete, stirring was continued for 1 hour. Dichloromethane was added to the resulting liquid, and the aqueous layer was extracted, post-treated, and purified using a column chromatography to obtain the compound containing the secondary alcohol ketated.

[0269] The mixture was cooled to 0°C in an ice bath. 250 mL of a methanol-acetic acid mixture (volume ratio 10:1) was added to 41.4 g of the compound obtained by ketalizing the secondary alcohol, along with 2.7 g of 2-methylpyridine-borane. The ice bath was removed, and the mixture was stirred overnight in an open system at room temperature. After concentration, the mixture was cooled to 0°C, and 360 mL of a 35% hydrochloric acid aqueous solution was added. The mixture was stirred at room temperature for 2 hours. An aqueous sodium hydroxide solution was added to make the mixture alkaline. The aqueous layer was extracted with dichloromethane, post-treated, and purified in a column to obtain additive C as a polyetheramine. The structure of R31 of additive C and the values ​​of v and w are shown in Table 5.

[0270] Except for the use of additive C in the resin coating material, the resin coating material was prepared from the materials shown in Table 7, the impregnation treatment solution was prepared from the materials shown in Table 8, and the electrophotographic roller of Comparative Example 2 was manufactured using the combination shown in Table 9, in the same manner as in Example 1. The obtained electrophotographic roller was evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0271] Comparative Example 3

[0272] Polyoxyethylene hexadecyl ether acetate: Synthesis of Additive D

[0273] 315.2 g of 1-hexadecyl alcohol (from Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were placed together in an autoclave equipped with a stirrer, temperature controller, and automatic feeder, and dehydrated at 110 °C and 1.2 kPa for 30 minutes. After dehydration, the mixture was purged with nitrogen, the temperature was raised to 150 °C, and then 858.0 g of ethylene oxide (15 mol relative to the alcohol) was added. The reaction was carried out at 150 °C for 1 hour to obtain an ethylene oxide adduct with an average addition mole of 15 mol.

[0274] A total of 90.2 g of the obtained ethylene oxide adduct was mixed with 510 mL of 1 mol / L sodium hydroxide aqueous solution, 71.1 g of potassium permanganate was added, and the mixture was stirred at room temperature for 6 hours. Then, 760 mL of 2-propanol was added and stirred for 1 hour to quench the excess potassium permanganate, and the byproduct manganese oxide was filtered off. The aqueous layer was extracted and purified with dichloromethane to obtain additive D as polyoxyethylene hexadecyl ether acetic acid. The structure and x value of R41 of additive D are shown in Table 5.

[0275] Except for the use of additive D in the resin coating material, the resin coating material was prepared from the materials shown in Table 7, the impregnation treatment solution was prepared from the materials shown in Table 8, and the electrophotographic roller of Comparative Example 3 was manufactured using the combination shown in Table 9, in the same manner as in Example 1. The obtained electrophotographic roller was evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0276] [Table 5]

[0277]

[0278] Comparative Example 5

[0279] Referring to the embodiment in Japanese Patent Application Publication No. 2003-113347, the materials shown in Table 6 were used, and the mixture was stirred with zirconia beads using a paint mixer for 1 hour to obtain resin coating material 20.

[0280] Except that the resin layer uses resin coating material 20, the electrophotographic roller of Comparative Example 5 was manufactured using the same method as in Example 1. The obtained electrophotographic roller was evaluated using the same method as in Example 1. The evaluation results are shown in Table 9.

[0281] [Table 6]

[0282]

[0283] The materials listed in the table are as follows.

[0284] -ME823LP: (Manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)

[0285] -A-187: (Manufactured by Momentive Co., Ltd.)

[0286] -Disperbyk-185: (Made by BYK Co., Ltd.)

[0287] -MA77: (Manufactured by Mitsubishi Chemical Corporation)

[0288] -FF-101(D): (Manufactured by Dainichiseika Color & Chemicals Mfg.Co.,Ltd.)

[0289] -GS-30: (Manufactured by Toa Gosei Co., Ltd.)

[0290] -C400T: Art Pearl C400T crosslinked urethane resin particles (manufactured by Negami Chemical Industrial Co., Ltd., average particle size 15 μm) [Table 7]

[0291]

[0292] *The numbers in the table represent the amount of each material in parts by mass. *The materials listed in the table are as follows.

[0293] polyols

[0294] -Kuraray Polyol C2090: Polycarbonate polyol (manufactured by Kuraray Co., Ltd., molecular weight 2000)

[0295] -Kuraray Polyol C3090: Polycarbonate polyol (manufactured by Kuraray Co., Ltd., molecular weight 3000)

[0296] -PTMG1000: Polytetramethylene glycol (manufactured by Hodogaya Chemical Co., Ltd., molecular weight 1000)

[0297] -PTMG650: Polytetramethylene glycol (manufactured by Hodogaya Chemical Co., Ltd., molecular weight 650)

[0298] -PTGL1000: Polyether polyol (manufactured by Hodogaya Chemical Co., Ltd.)

[0299] Isocyanates

[0300] Millionate MR-400: An isocyanate compound, polymeric MDI (manufactured by Tosoh Corporation).

[0301] additive

[0302] -Unilube 50MB-26: Polyoxyethylene polyoxypropylene butyl ether (manufactured by NOF Corporation)

[0303] -JEFFAMINE M-2005: Polyetheramine (manufactured by Huntsman Co.)

[0304] -Nonion A-13PR: Polyoxyethylene polyoxypropylene lauryl ether (manufactured by NOF Corporation)

[0305] -Typol Soft ECA-490: Polyoxyethylene lauryl ether acetate (manufactured by Taiko Oil Chem. Co., Ltd.)

[0306] -Unisafe 20P-8: Polyoxyethylene polyoxypropylene hexadecyl ether (manufactured by NOF Corporation)

[0307] -Newpol 50HB-100: (Poly(ethylene oxide propylene oxide) glycol monobutyl ether (manufactured by Sanyo Chemical Industries, Ltd.))

[0308] Modified silicone oil

[0309] -TSF4445: Modified organosilicon compound (manufactured by Momentive Performance Materials Japan, Inc.)

[0310] carbon black

[0311] -MA8: Carbon black (manufactured by Mitsubishi Chemical Corporation, primary particle number average diameter: 24 nm, DBP absorbance: 51 mL / 100 g, pH: 3.0)

[0312] -SUNBLACK X55 (manufactured by Asahi Carbon Co., Ltd., primary particle number average diameter: 25nm, DBP absorption: 77mL / 100g, pH: 3.0)

[0313] -MA11: Carbon black (manufactured by Mitsubishi Chemical Corporation, primary particle number average diameter: 29 nm, DBP absorbance: 64 mL / 100 g, pH: 3.5)

[0314] -SUNBLACK X15: (Made by Asahi Carbon Co., Ltd., primary particle number average diameter: 20nm, DBP absorption: 96mL / 100g, pH: 3.5)

[0315] Roughness forms particles

[0316] -Art Pearl C400T: Cross-linked urethane resin particles (manufactured by Negami Chemical Industries Co., Ltd., average particle size 15μm)

[0317] -Daimic Beads UCN-5090: Cross-linked urethane resin particles (manufactured by Dainichiseika Chemicals Co., Ltd., average particle size 9 μm)

[0318] [Table 8]

[0319]

[0320] *The numbers in the table represent the amount of each material in parts by mass.

[0321] The materials listed in the table are as follows.

[0322] EBECRYL145: A bifunctional acrylic monomer (manufactured by Daicel-Allnex Corporation)

[0323] TMPTA: Trifunctional acrylic monomer (manufactured by Daicel-Allnex Corporation)

[0324] Omnirad 184: Photopolymerization initiator (manufactured by IGM Resins Co., Ltd.)

[0325]

[0326] In Examples 1-9 and 16, and Comparative Examples 1-4 and 6, it was confirmed that the cross-linked urethane resin and the cross-linked acrylic resin formed an interpenetrating polymer network (IPN) structure in the first region.

[0327] According to this disclosure, an electrophotographic roller can be provided, wherein scratches caused by grinding and cracks caused by the inward propagation of scratches can be suppressed even during prolonged and repeated use in high and low temperature environments. Furthermore, according to this disclosure, a processing cartridge that contributes to the stable formation of high-quality electrophotographic images can be provided. Additionally, according to this disclosure, an electrophotographic image forming apparatus capable of forming high-quality electrophotographic images can be provided.

[0328] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. An electrophotographic roller having a conductive substrate and a resin layer on the outer peripheral surface of the substrate, wherein... The thickness of the resin layer is 2.0–30.0 μm. The resin layer comprises a binder resin and carbon black dispersed in the binder resin. The arithmetic mean Rc of the spherical equivalent diameter of the carbon black in the resin layer is less than 80 nm. The arithmetic mean d of the distance between the walls of the carbon black in the resin layer is 60–170 nm, and When the elastic modulus of the adhesive resin, measured in a cross section along the thickness direction of the resin layer, in a first region from the outer surface of the resin layer to a depth of 0.1 μm, is defined as E1, E1 satisfies the following equation (1): E1≥200MPa...(1).

2. The electrophotographic roller of claim 1, wherein the binder resin comprises a cross-linked urethane resin.

3. The electrophotographic roller according to claim 1, wherein the resin layer comprises at least one compound selected from the group consisting of a compound having a structure represented by the following structural formula (2), a compound having a structure represented by the following structural formula (3), and a compound having a structure represented by the following structural formula (4): In structural formula (2), R21 represents a monovalent hydrocarbon group with 1 to 12 carbon atoms, and t and u are the average number of moles added, each independently representing a number greater than 1; In structural formula (3), R31 represents a monovalent hydrocarbon group with 1 to 8 carbon atoms, and v and w are the average molar number of additions, each independently representing a number greater than 1; and In structural formula (4), R41 represents a monovalent hydrocarbon group with 1 to 12 carbon atoms, and x is the average number of moles added and represents a number greater than 1.

4. The electrophotographic roller according to claim 1, wherein... E1 is above 250MPa, and When the elastic modulus of the adhesive resin in the second region extending from the outer surface of the resin layer to a depth of 1.0–1.1 μm is expressed as E2, E2 is 120-200 MPa.

5. The electrophotographic roller according to claim 1, wherein... The resin layer comprises cross-linked urethane resin and cross-linked (meth)acrylic resin, and The cross-linked urethane resin and the cross-linked (meth)acrylic resin form an interpenetrating polymer network structure in the first region.

6. The electrophotographic roller of claim 1, wherein the binder resin comprises a cross-linked urethane resin, and The cross-linked urethane resin has a polycarbonate structure.

7. The electrophotographic roller according to claim 1, wherein... The arithmetic mean Rc of the equivalent diameter of the circle is less than 60 nm. When the standard deviation of the equivalent diameter of the circle is expressed as σc, σc / Rc is 0.000 to 0.

650. The arithmetic mean d of the distance between the walls is 80–150 nm, and When the standard deviation of the distance between the walls is expressed as σd, σd / d is 0.000 to 0.

600.

8. The electrophotographic roller according to any one of claims 1 to 7, wherein The number average diameter of the primary particles of the carbon black is less than 30 nm. The carbon black has a DBP absorption of less than 90 mL / 100 g, and The pH of the carbon black is below 4.

0.

9. A processing box configured to be detachably mounted to the body of an electrophotographic image forming apparatus, wherein... The processing box has an electrophotographic roller according to any one of claims 1 to 8.

10. An electrophotographic image forming apparatus, comprising: Image carrier component used to carry electrostatic latent images; A charging roller for energizing the image-carrying component once; and a developing roller for developing the electrostatic latent image with toner to form a toner image, wherein The charging roller and the developing roller, or both of them, are electrophotographic rollers according to any one of claims 1 to 8.

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