Electrophotographic member and manufacturing method thereof, process cartridge and electrophotographic image forming apparatus

Abstract

To provide a member for electrophotography that can reduce the contact pressure of a cleaning member against a photoreceptor, or even in an electrophotographic image forming apparatus from which a cleaning member is removed, can reduce the amount of a discharge product attached to an outer surface of a photoreceptor and better prevent image deletion.SOLUTION: A member for electrophotography has a substrate having conductivity, and a single-layer surface layer on the substrate. The surface layer has a matrix including cross-linked resin as a binder. The surface layer holds particles including an inorganic laminar compound having an ion exchange ability such that at least part of each particle is exposed from an outer surface of the surface layer. In an area from the outer surface of the surface layer to a depth of 0.1 μm on a cross section in a thickness direction of the surface layer, the measured modulus of elasticity of the matrix is 200 MPa or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic member and a method for manufacturing the same, a process cartridge, and an electrophotographic image forming apparatus. [Background technology]

[0002] The image formation process in an electrophotographic image forming apparatus involves charging the outer surface of a photoconductor, forming an electrostatic latent image on the charged outer surface of the photoconductor, developing the electrostatic latent image with toner, transferring the developed toner to a recording sheet, and fixing the transferred toner with heat and pressure. After transfer, some toner that was not transferred and remains on the outer surface of the photoconductor (hereinafter also referred to as "residual toner"), as well as compounds generated by discharge during the charging process (hereinafter also referred to as "discharge products"), may remain. Such residual toner and discharge products are scraped off and removed by a cleaning member placed in contact with the photoconductor. This is the general image formation process in an electrophotographic image forming apparatus.

[0003] In response to recent demands for greater energy savings in electrophotographic image forming apparatuses, efforts have been made to reduce the contact pressure of the cleaning member against the photoconductor and eliminate the cleaning member altogether. In the image formation process described above, high friction occurs between the cleaning member and the photoconductor. Reducing the contact pressure of the cleaning member against the photoconductor or eliminating the cleaning member allows the photoconductor to rotate with lower torque, thereby saving energy. However, reducing the contact pressure of the cleaning member against the photoconductor or eliminating the cleaning member can lead to the accumulation of residual toner and discharge products on the outer surface of the photoconductor, resulting in a deterioration in the quality of electrophotographic images. Patent Document 1 discloses a charging member with a surface layer containing hydrotalcite to prevent the adverse effects of discharge products adhering to and accumulating on the contact charging member on the photoconductor. Patent Document 2 also discloses an intermediate transfer member having a layered compound, such as a hydrotalcite-type compound, on its surface, which physically adsorbs discharge products. The discharge products include, for example, nitrogen oxides (NOx) produced when ozone generated during discharge reacts with nitrogen in the air, and also include nitric acid produced when the nitrogen oxides react with moisture in the air. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-310218 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-267454 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Documents 1 and 2 disclose reducing the amount of discharge products on the surface of a contact charging member or an intermediate transfer member. However, even if the techniques disclosed in Patent Documents 1 and 2 are applied to electrophotographic members, the effect of reducing the amount of discharge products on the outer surface of a photoreceptor with which the electrophotographic member contacts is limited, and there is still room for improvement.

[0006] One aspect of the present disclosure is directed to providing an electrophotographic member that can reduce the contact pressure of a cleaning member against a photosensitive member, or that can reduce the amount of discharge products adhering to the outer surface of a photosensitive member and better suppress image deletion even in an electrophotographic image forming apparatus that does not require a cleaning member. Another aspect of the present disclosure is directed to providing a process cartridge that contributes to the stable formation of high-quality electrophotographic images. Yet another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided an electrophotographic member having a conductive substrate and a single surface layer on the substrate, wherein the surface layer has a matrix containing a crosslinked resin as a binder, and the surface layer holds particles containing an inorganic layered compound having ion exchange ability such that at least a portion of the particles are exposed from the outer surface of the surface layer, and the elastic modulus of the matrix measured in a region to a depth of 0.1 μm from the outer surface of the surface layer in a cross section in the thickness direction of the surface layer is 200 MPa or more.

[0008] According to another aspect of the present disclosure, there is provided a method for producing an electrophotographic member, in which the surface layer is formed by a method including the following steps (i) to (iii): (i) a step of applying a coating material for forming a crosslinked polyurethane resin layer, which contains a polyol, an isocyanate compound, and particles containing an inorganic layered compound having ion exchange ability, onto a conductive substrate, and drying and solidifying or heat-curing the coating material to form a crosslinked polyurethane resin layer; (ii) a step of impregnating the crosslinked polyurethane resin layer with an impregnation treatment liquid containing a (meth)acrylic monomer, and then polymerizing and curing the (meth)acrylic monomer to form a surface layer having an interpenetrating polymer network structure in which the crosslinked polyurethane resin is interpenetrated with the crosslinked acrylic resin; (iii) A step of exposing at least a part of the particles containing the inorganic layered compound to the outer surface of the surface layer by performing an ultraviolet irradiation treatment.

[0009] According to another aspect of the present disclosure, there is provided a process cartridge that is detachably mountable to a main body of an electrophotographic image forming apparatus, the process cartridge including the electrophotographic member described above. According to yet another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus having an image carrier for carrying an electrostatic latent image and a member that abuts against the image carrier, the member that abuts against the image carrier being the electrophotographic member described above. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, it is possible to obtain an electrophotographic member that can reduce the contact pressure of the cleaning member against the photosensitive member, or even in an electrophotographic image forming apparatus that does not require a cleaning member, reduce the amount of discharge products that adhere to the outer surface of the photosensitive member, and better suppress image deletion. According to another aspect of the present disclosure, it is possible to obtain a process cartridge that contributes to the stable formation of high-quality electrophotographic images. According to yet another aspect of the present disclosure, it is possible to obtain an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a schematic cross-sectional view showing a developing roller according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a schematic configuration diagram illustrating a process cartridge according to one aspect of the present disclosure. [Figure 3] 1 is a schematic cross-sectional view illustrating an electrophotographic image forming apparatus according to one embodiment of the present disclosure. [Figure 4] 1 is a schematic cross-sectional view of an electrophotographic member according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Even when the techniques disclosed in Patent Documents 1 and 2 are applied to electrophotographic members, the effect of reducing the amount of discharge products on the outer surface of a photoreceptor with which the electrophotographic member contacts is limited. The present inventors speculate that the reason for this is as follows: Layered compounds with ion adsorption ability, such as hydrotalcite, can retain nitrate ions between layers. However, under circumstances in which a larger amount of discharge products adheres to the surface of the photoreceptor due to a reduction in the contact pressure of the cleaning member against the photoreceptor or the elimination of the cleaning member, it is believed that relying solely on the adsorption of discharge products by hydrotalcite on the surface of the electrophotographic member is insufficient. Therefore, as a result of further investigation, the present inventors have found that an electrophotographic member having a surface layer having the following configuration contributes to further reducing the amount of discharge products on the outer surface of the photoreceptor. The surface layer has a matrix containing a crosslinked resin as a binder, and holds particles containing an inorganic layered compound having ion exchange capacity such as hydrotalcite so that at least a portion of the particles is exposed from the outer surface, and the elastic modulus of the matrix measured in a region from the outer surface to a depth of 0.1 μm is 200 MPa or more.

[0013] The inventors speculate as follows about the reason why an electrophotographic member having such a surface layer can effectively remove discharge products from the outer surface of a photoreceptor. The use of the adsorption ability of discharge products by an inorganic layered compound with ion exchange capacity is similar to the inventions described in Patent Documents 1 and 2. However, the surface layer according to one embodiment of the present disclosure has an extremely high matrix elastic modulus of 200 MPa or more measured in the outermost surface region extending to a depth of 0.1 μm from the outer surface. A matrix exhibiting such a high elastic modulus has an extremely high crosslink density. When discharge products migrated from a photoreceptor adhere to the outer surface of a surface layer composed of such a matrix, the discharge products rapidly diffuse across the outer surface of the electrophotographic member. That is, the discharge products migrated from the photoreceptor do not remain at the contact point between the electrophotographic member and the photoreceptor, but diffuse around the contact point and are adsorbed by the layered compound present around the contact point. As a result, a larger amount of discharge products are adsorbed by the layered compound of the electrophotographic member. As a result, it is believed that it is possible to reduce the amount of discharge products on the outer surface of the photosensitive member even in situations where a larger amount of discharge products adheres to the surface of the photosensitive member due to a reduction in the contact pressure of the cleaning member against the photosensitive member or the elimination of the cleaning member.

[0014] Furthermore, the surface layer of the electrophotographic member according to the present disclosure holds at least some of the particles containing an inorganic layered compound with ion exchange capacity, exposed from the outer surface of the surface layer. The inorganic layered compound has a layered structure in which cation layers composed of various metal ions or complex ions in which various ligands are coordinated to these metal ions are alternately arranged with anion layers composed of their counterions. The ions constituting the cation or anion layer are replaced with other ions to exhibit ion exchange capacity. As explained in the Background Art section, "discharge products" include NOx and nitric acid, and substances that adhere to the outer surface of the photoreceptor include aqueous nitric acid solutions containing nitrate anions. In the present disclosure, anions constituting the anion layer exchange with nitrate anions contained in the discharge products, thereby incorporating nitrate anions into the layered structure. The incorporation of nitrate anions continues until all anions in the anion layer are replaced with nitrate anions. Furthermore, if excess nitrate anions are present, it is presumed that the remaining nitrate anions are expelled from the end of the layered structure. The discharged nitrate anions travel along the outer surface composed of the matrix and are re-incorporated into the nearby layered structure. That is, the inorganic layered compound functions to transport the nitrate anions derived from the discharge products along the layered structure, and this function is thought to promote the diffusion of the discharge products toward the surface of the electrophotographic member. It is believed that these effects allow the discharge products to be efficiently transferred to the surface of the electrophotographic member and removed from the outer surface of the photoreceptor, resulting in the effect of suppressing the occurrence of image deletion.

[0015] [Electrophotographic materials] The electrophotographic member according to the present disclosure may be any member that comes into contact with a photoreceptor, which is an image bearing member. In particular, it is preferable that the member comes into contact with the photoreceptor immediately after the generation of discharge products. Hereinafter, the present disclosure will be described using an electrophotographic member having a roller shape (hereinafter also referred to as an "electrophotographic roller") that can be suitably used as an electrophotographic member according to one embodiment of the present disclosure, but the shape of the electrophotographic member is not limited thereto. Fig. 1(a) is a circumferential cross-sectional view of an electrophotographic roller 1 having a mandrel 2 as a conductive substrate and a surface layer 3 on the circumferential surface of the substrate. Fig. 1(b) is a circumferential cross-sectional view of an electrophotographic roller 1 having a mandrel 2 as a conductive substrate, an intermediate layer 4 on the circumferential surface of the mandrel 2, and a surface layer 3 on the circumferential surface of the intermediate layer 4. The intermediate layer 4 is not limited to a single layer, and may be a multi-layer structure.

[0016] <1: Conductive substrate> The conductive substrate may be a cylindrical or hollow cylindrical conductive mandrel, or such a mandrel with one or more conductive intermediate layers provided thereon.

[0017] <1-1: Mandrel> The mandrel has a cylindrical or hollow cylindrical shape and is made of the following conductive materials: metals or alloys such as aluminum, copper alloys, and stainless steel; iron plated with chromium or nickel; and conductive synthetic resins. A known adhesive may be applied to the surface of the mandrel to improve adhesion to an intermediate layer or surface layer provided on its outer periphery.

[0018] <1-2: Middle class> In a non-magnetic one-component contact development process, an electrophotographic member having an intermediate layer laminated between a mandrel and a surface layer is preferably used. The intermediate layer provides the electrophotographic member with the hardness and elasticity required to be pressed against the photoreceptor with an appropriate nip width and nip pressure so that toner can be supplied to the electrostatic latent image formed on the surface of the photoreceptor without excess or deficiency. The intermediate layer is typically preferably formed from a molded rubber material. Examples of rubber materials include 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, NBR hydride, and urethane rubber. These materials can be used alone or in combination. Among these, silicone rubber is particularly preferred because it is less likely to develop compression set even when in contact with other members (such as a toner control member) over a long period of time. Specific examples of silicone rubber include cured products of addition-curing silicone rubber.

[0019] In the intermediate layer, a conductivity imparting agent such as an electronically conductive substance or an ionic conductive substance can be blended into the rubber material as needed. The volume resistivity of the intermediate layer is preferably 10 3 Ωcm or more 10 11 Ωcm or less, more preferably 10 4 Ωcm or more 10 10 It is adjusted to Ωcm or less. Examples of electronically conductive substances include conductive carbon blacks such as "Ketjenblack" (trade name, manufactured by Lion Specialty Chemicals Co., Ltd.) and acetylene black; rubber carbon blacks such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; oxidation-treated carbon blacks for color inks; pyrolytic carbon black; and metals such as copper, silver, and germanium and their metal oxides. Examples of ion-conductive substances include inorganic ion-conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and organic ion-conductive substances such as modified aliphatic dimethylammonium ethosulfate and stearylammonium acetate. These conductivity imparting agents are used in the amount necessary to adjust the intermediate layer to the appropriate volume resistivity as described above, and are typically used in the range of 0.5 parts by mass to 50 parts by mass per 100 parts by mass of the rubber material.

[0020] The intermediate layer may further contain various additives, such as plasticizers, fillers, extenders, vulcanizing agents, vulcanization aids, crosslinking aids, cure inhibitors, antioxidants, antioxidants, and processing aids, as needed. Examples of fillers include silica, quartz powder, and calcium carbonate. These optional components are blended in amounts that do not impair the function of the intermediate layer. The intermediate layer has the elasticity required for electrophotographic members, and preferably has an Asker C hardness of 20 degrees or more and 100 degrees or less, and a thickness of 0.3 mm or more and 6.0 mm or less. The materials for forming the intermediate layer can be mixed using a dynamic mixer such as a single-screw continuous kneader, a twin-screw continuous kneader, a twin-roll mill, a kneader mixer, or a trimix, or a static mixer such as a static mixer.

[0021] The method for forming the intermediate layer on the mandrel is not particularly limited, and examples thereof include molding, extrusion, injection, and coating. In molding, for example, first, pieces for holding the mandrel in the mold are fixed to both ends of a cylindrical mold, and injection ports are formed in the pieces. Next, the mandrel is placed in the mold, and the material for forming the intermediate layer is injected through the injection port. The mold is then heated to a temperature at which the material hardens, and the mold is demolded. In extrusion, for example, the mandrel and the material for forming the intermediate layer are extruded together using a crosshead extruder, and the material is hardened to form the intermediate layer around the mandrel. The surface of the intermediate layer can be modified by surface modification methods such as surface polishing, corona treatment, flame treatment, and excimer treatment to improve adhesion to the surface layer.

[0022] <2: Surface layer> The surface layer is a single layer provided on the outermost surface of the electrophotographic member, and in the case of a roller-shaped member, it is provided on the outermost peripheral surface. The surface layer can be formed directly on the mandrel, or it can be formed on the outer peripheral surface of a mandrel having an intermediate layer provided thereon as a base. The surface layer contains a matrix containing a crosslinked resin as a binder and particles containing an inorganic layered compound with ion exchange capacity. Furthermore, the surface layer can contain various additives, such as a conductivity imparting agent for controlling conductivity and a roughening agent for controlling surface roughness, as needed, within the scope of the present disclosure. The material constituting the matrix containing a crosslinked resin as a binder is not particularly limited. However, a material having an interpenetrating polymer network structure (hereinafter referred to as "IPN structure") in which a crosslinked acrylic resin interpenetrates a crosslinked polyurethane resin is preferably used because of its excellent frictional charging performance and abrasion resistance to the toner, and because it is easy to design the elastic modulus within a desired range. In other words, it is preferable that at least a portion of the outer surface of the surface layer is composed of a matrix having an IPN structure in which a crosslinked acrylic resin interpenetrates a crosslinked polyurethane resin.

[0023] <2-1: Cross-linked polyurethane resin> Examples of crosslinked polyurethane resins include polyether-based polyurethane resins, polyester-based polyurethane resins, polycarbonate-based polyurethane resins, etc. These polyurethane resins can be obtained by reacting a known polyol with an isocyanate compound. Specific examples of polyols include, but are not limited to, polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyester polyols such as polyethylene succinate diol, polybutylene succinate diol, polyethylene adipate diol, and polybutylene adipate diol; and polycarbonate polyols such as polyethylene carbonate diol and polybutylene carbonate diol. The isocyanate compound to be reacted with these polyols is not particularly limited, and examples thereof include aliphatic polyisocyanates such as ethylene diisocyanate and 1,6-hexamethylene diisocyanate (HDI); alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), cyclohexane 1,3-diisocyanate, and cyclohexane 1,4-diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; and copolymers, isocyanurates, TMP adducts, biurets, and blocks thereof. Among these, aromatic isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate are more preferably used.

[0024] <2-2: Cross-linked acrylic resin> Although cross-linked acrylic resins have high strength, they can be hard and brittle when used alone. Therefore, when used as a single film in the surface layer of an electrophotographic member, their brittleness makes them prone to scratches caused by friction. On the other hand, when cross-linked acrylic resins are incorporated into an IPN structure with a cross-linked polyurethane resin, they are less likely to become brittle and can be suitably used as the surface layer of an electrophotographic member. Furthermore, by forming an IPN structure in the matrix of the surface layer, the cross-linking density can be increased, and this high cross-linking density matrix provides unique surface properties that inhibit the penetration of discharge products into the interior of the member. Crosslinked acrylic resins (including crosslinked methacrylic resins) are formed by polymerization of (meth)acrylic monomers. Here, the term "(meth)acrylic monomer" refers to either an acrylic monomer or a methacrylic monomer. In other words, crosslinked acrylic resins are formed by polymerization of either an acrylic monomer, a methacrylic monomer, or both.

[0025] An IPN structure of a crosslinked acrylic resin and a crosslinked polyurethane resin is formed by impregnating a resin layer containing a crosslinked polyurethane resin with a liquid (meth)acrylic monomer and then curing the resulting mixture. To form a crosslinked structure, a polyfunctional monomer having multiple acryloyl and / or methacryloyl groups as functional groups is used as the (meth)acrylic monomer. On the other hand, if the (meth)acrylic monomer has four or more functional groups, the viscosity of the (meth)acrylic monomer increases significantly, making it difficult for the (meth)acrylic monomer to impregnate the surface of the resin layer made of the crosslinked polyurethane resin, resulting in the formation of an IPN structure. Therefore, a (meth)acrylic monomer having a total of two or three acryloyl and / or methacryloyl groups per molecule is preferred, and a bifunctional (meth)acrylic monomer having two acryloyl and / or methacryloyl groups per molecule is more preferred. Furthermore, a monofunctional monomer may be combined with the polyfunctional monomer as needed.

[0026] The average molecular weight of the (meth)acrylic monomer is preferably in the range of 200 to 750. By using a (meth)acrylic monomer having an average molecular weight in this range, an IPN structure can be easily formed relative to the network structure of the crosslinked polyurethane resin, and the strength of the surface layer can be effectively improved. As mentioned above, the (meth)acrylic monomer is impregnated into the resin layer containing the crosslinked polyurethane resin. Therefore, the (meth)acrylic monomer must have an appropriate viscosity. That is, if the viscosity is high, it is difficult to impregnate the resin layer, and if the viscosity is low, it is difficult to control the impregnation state. Therefore, the viscosity of the (meth)acrylic monomer is preferably 5.0 mPa·s or more and 140 mPa·s or less at 25°C. The viscosity can be measured, for example, using a piston-type viscometer, VISCOlab4000 (trade name, manufactured by Cambridge Viscocity).

[0027] Preferably, one or more (meth)acrylic monomers satisfying the above-mentioned molecular weight and viscosity ranges are selected, impregnated into a resin layer containing a crosslinked polyurethane resin, and polymerized to form an IPN structure of a crosslinked polyurethane resin and a crosslinked acrylic resin. The polymerization method for the (meth)acrylic monomer is not particularly limited, and known methods can be used. Specific examples include heating and ultraviolet irradiation. Known radical polymerization initiators and ionic polymerization initiators can be used for each polymerization method.

[0028] Examples of the polymerization initiator when polymerizing by heating include peroxides such as 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-butylperoxypivalate, t-amylperoxynormaloctoate, t-butylperoxy2-ethylhexylcarbonate, dicumyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, 1,1-bis(t-butylperoxy)cyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate; Examples of azo compounds include 2,2-azobisbutyronitrile, 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-methylbutyronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2-azobis(N-butyl-2-methoxypropionamide), dimethyl-2,2-azobis(isobutyrate), and 4,4'-azobis(4-cyanovaleric acid) (ACVA).

[0029] Examples of the polymerization initiator when polymerizing by irradiation with ultraviolet light include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan- 1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0030] These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.5 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total amount of compounds for forming the specific resin (for example, a (meth)acrylic monomer having a (meth)acryloyl group), from the viewpoint of efficiently progressing the reaction. Known heating devices and ultraviolet ray irradiation devices can be used appropriately for polymerization. Examples of light sources that can be used for irradiating ultraviolet rays include LED lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and low-pressure mercury lamps. The cumulative light intensity required for polymerization can be adjusted appropriately depending on the types and amounts of monomer compounds and polymerization initiators used.

[0031] <2-3: Inorganic layered compounds with ion exchange capacity> The inorganic layered compound with ion exchange ability is a compound having a layered structure in which cation layers consisting of various metal ions or complex ions in which various ligands are coordinated to these metal ions and anion layers consisting of their counter ions are alternately arranged. Examples of metal ions include, but are not limited to, Li + , Na + , K. + , Mg 2+ , Fe 2+ , Zn 2+ , Ca 2+ , Ni 2+ , Co 2+ , Cu 2+ , Al 3+ , Cr 3+ , Fe 3+ , Mn 3+Examples of counter ions include carbonate ions, sulfate ions, hydroxide ions, carboxylate ions, and halide ions, with carbonate ions and hydroxide ions being preferred. The reason why carbonate ions and hydroxide ions are preferred is explained below. That is, when these anions exchange with nitrate anions derived from the discharge products and are released from the layer structure of the inorganic layered compound, they react with protons derived from the discharge products. Specifically, carbonate ions generate water and carbon dioxide according to the following reaction formula (1), and hydroxide ions generate water according to the following reaction formula (2). These products volatilize into the atmosphere and do not affect the surface resistance of the photoreceptor. Reaction (1): CO3 2- +2H + →H2O+CO2 Reaction formula (2): OH - +H + →H2O Carbonate ions are particularly preferred because they have an ionic diameter close to that of nitrate anions, which are the target of ion exchange, and can be easily exchanged.

[0032] A specific example of an inorganic layered compound with ion exchange capacity is Mg6Al2(CO3)(OH) 16 Hydrotalcite compounds represented by the formula nH2O, lithium aluminum oxide (LiAlO2), desautelcite (Mg6Mn2(CO3)(OH) 16 ·4H2O), Iowite (Mg6Fe2(OH) 16 Cl2·4H2O), pyroaurite (Mg6Fe2(CO3)(OH) 16 ·4H2O), Stichtite (Mg6Cr2(CO3)(OH) 16 ·4H2O), Takovite (Ni6Al2(CO3)(OH) 16 ·4H2O), Wermullandite (Mg7(Ca,Mg)(Al,Fe)2(SO4)2(OH) 18 ·12H2O), Zaccagnite (Zn4Al2(CO3)(OH) 12 Examples include compounds derived from natural minerals such as arginine, arginine, and arginine. In the surface layer, the content of the inorganic layered compound having ion exchange ability is preferably 1% by mass or more and 40% by mass or less based on the total mass of the surface layer, from the viewpoint of adjusting the hardness and resistance of the surface layer to an appropriate range as an electrophotographic member.

[0033] <2-4: Conductive agent> The surface layer may contain a conductivity imparting agent such as an electronically conductive substance or an ionic conductive substance, if necessary. The volume resistivity of the surface layer is preferably 10 3 Ωcm or more 10 11 Ωcm or less, more preferably 10 4 Ωcm or more 10 10 It is adjusted to Ωcm or less. Examples of electronically conductive substances include conductive carbon blacks such as "Ketjenblack" (trade name, manufactured by Lion Specialty Chemicals Co., Ltd.) and acetylene black; rubber carbon blacks such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; oxidation-treated carbon blacks for color inks; pyrolytic carbon black; and metals such as copper, silver, and germanium and their metal oxides. Examples of ion-conductive substances include inorganic ion-conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and organic ion-conductive substances such as modified aliphatic dimethylammonium ethosulfate and stearylammonium acetate. These conductivity-imparting agents are used in an amount necessary to adjust the surface layer to the appropriate volume resistivity as described above. Typically, electronically conductive substances are used in an amount of 1 part by mass to 50 parts by mass, and ionically conductive substances are used in an amount of 0.01 parts by mass to 20 parts by mass, per 100 parts by mass of the cross-linked polyurethane resin.

[0034] <2-5: Roughening agent> A roughening agent may be added to the surface layer for the purpose of forming convex portions on the surface of the electrophotographic member. Examples of the roughening agent include fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, and polycarbonate resin. The volume average particle diameter of the fine particles is preferably 1.0 μm or more and 30 μm or less, and the surface roughness (ten-point average roughness) Rzjis formed by the fine particles is preferably 0.1 μm or more and 20 μm or less. Rzjis is a value measured according to JIS B0601 (1994). When a roughening agent is added to the surface layer, the amount of the roughening agent added may be, for example, 1 part by mass or more and 150 parts by mass or less per 100 parts by mass of the crosslinked polyurethane resin.

[0035] <2-6: Various additives> In addition to those described above, the surface layer may contain various additives such as a crosslinking agent, a crosslinking aid, a plasticizer, a filler, an extender, a vulcanizing agent, a vulcanization aid, an antioxidant, an antiaging agent, a processing aid, a dispersant, and a leveling agent, as long as the additives do not impair the features of the present disclosure.

[0036] <2-7: Method for forming surface layer> A method for forming an example of an embodiment of the surface layer of the present disclosure will be described below. In the embodiment described here, the surface layer has a matrix containing a crosslinked resin as a binder, and the matrix has an IPN structure in which a crosslinked acrylic resin interpenetrates a crosslinked polyurethane resin. The surface layer also holds particles containing an inorganic layered compound with ion exchange capacity, with at least a portion of the particles exposed from the outer surface of the surface layer. Note that this embodiment is merely an example, and the surface layer of the present disclosure is not limited thereto. The surface layer of this embodiment can be formed by a method including the following steps (i) to (iii): (i) crosslinked polyurethane resin layer forming step; (ii) a step of forming an IPN structure of a cross-linked polyurethane resin and a cross-linked acrylic resin; (ii) A step of exposing particles containing an inorganic layered compound.

[0037] (Step (i): Crosslinked polyurethane resin layer forming step) The method for forming the resin layer containing the crosslinked polyurethane resin is not particularly limited, but a method of forming the layer by applying a liquid paint is preferred. For example, the materials for forming the resin layer are dispersed and mixed in a solvent to form a paint, and the resulting paint for forming the resin layer is applied to a conductive substrate, and then dried and solidified or heat-cured to form a crosslinked polyurethane resin layer. The materials for forming the resin layer referred to here include polyols and isocyanate compounds, which are raw materials for the crosslinked polyurethane resin, as well as particles containing an inorganic layered compound with ion exchange capacity. Furthermore, the materials for forming the resin layer may also include the aforementioned conductivity imparting agent, roughening agent, and various additives, as necessary. Polar solvents are preferred as solvents in terms of compatibility with the polyols and isocyanate compounds, which are raw materials for the crosslinked polyurethane resin. 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. Among these, solvents with high compatibility with other materials can be used alone or in combination of two or more. The solids concentration when forming the paint can be freely adjusted by the amount of solvent added. However, a concentration of 20% by mass or more and 40% by mass or less is preferred from the viewpoint of uniformly dispersing the materials for forming the resin layer. For dispersion and mixing, known dispersing devices using beads, such as a sand mill, paint shaker, dyno mill, and pearl mill, can be used. The resin layer-forming coating material obtained by this dispersion and mixing is applied to a conductive substrate to form a crosslinked polyurethane resin layer containing particles containing an inorganic layered compound having ion exchange capacity. The resin layer-forming coating material can be applied by dip coating, ring coating, spray coating, or roll coating.

[0038] The thickness of the crosslinked polyurethane resin layer thus obtained is preferably 2.0 μm or more from the viewpoint of film strength. Furthermore, although there is no particular upper limit on the thickness of the surface layer, when a single surface layer is formed on a substrate on which an intermediate layer has been formed, from the viewpoint of flexibility, it is 20 μm or less, preferably 16 μm or less, and more preferably 15 μm or less. The thickness of the surface layer here refers to the thickness of the part excluding the part that protrudes convexly due to the addition of a roughening agent or the like.

[0039] (Step (ii): Step of forming an IPN structure of cross-linked polyurethane resin and cross-linked acrylic resin) The crosslinked polyurethane resin layer formed as described above is impregnated with a liquid (meth)acrylic monomer. The liquid (meth)acrylic monomer can be impregnated as is or as an impregnation treatment liquid diluted appropriately with various solvents. By appropriately diluting the liquid (meth)acrylic monomer with various solvents, a surface layer with a more uniform surface composition can be obtained. The solvent can be freely selected as long as it satisfies both the affinity with the resin layer and the solubility of the (meth)acrylic monomer. 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. In addition, a polymerization initiator can be appropriately mixed into the impregnation treatment liquid. The method for impregnating the resin layer with the impregnation treatment liquid is not particularly limited, and methods such as dip coating, ring coating, spray coating, and roll coating can be used. After the resin layer is impregnated with the impregnation treatment solution, the (meth)acrylic monomer is polymerized and cured to form a surface layer. The polymerization and curing method is not particularly limited, and known methods can be used. Specific examples include heat curing and ultraviolet irradiation, but ultraviolet irradiation is preferably used because it has the advantage of being able to simultaneously perform the "step (iii): exposing the particles containing the inorganic layered compound" described below. Through the above steps, it is possible to form an IPN structure in which the crosslinked acrylic resin is introduced into the network structure of the crosslinked polyurethane resin in an intertwined manner.

[0040] (Step (iii): Exposing Particles Containing Inorganic Layered Compound) The particles containing an inorganic layered compound having ion exchange capacity are contained in the crosslinked polyurethane resin layer formed in the above-mentioned step (i). The method for exposing the particles containing the inorganic layered compound to the outer surface of the surface layer is not particularly limited, but a method using ultraviolet light irradiation is preferred. As mentioned above, in step (ii), when the acrylic resin impregnated in the resin layer is cured by ultraviolet light irradiation, the particles containing the inorganic layered compound can be exposed simultaneously with the curing of the acrylic resin. When ultraviolet light is irradiated, the energy of the ultraviolet light cuts off a portion of the molecular chains constituting the matrix on the outer surface of the surface layer. Alternatively, ultraviolet light excites oxygen molecules in the air, generating active oxygen species such as ozone, and the oxidation action of these active oxygen species cuts off a portion of the molecular chains constituting the matrix on the outer surface of the surface layer. In either case, the cut-off portion of the matrix volatilizes into the air. This action removes the matrix covering the particles containing the inorganic layered compound, exposing at least a portion of the particles containing the inorganic layered compound to the outer surface.

[0041] It should be noted that any known ultraviolet ray irradiation device can be used as appropriate. Examples of light sources that can be used to irradiate ultraviolet rays include LED lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and low-pressure mercury lamps. The illuminance of the ultraviolet rays on the outer surface of the surface layer should be 10 mW / cm from the viewpoint of keeping the wettability of the outer surface of the surface layer with respect to discharge products within an appropriate range. 2 In addition, from the viewpoint of not impairing the flexibility required for a member that contacts the photosensitive member, the illuminance of ultraviolet light on the outer surface of the surface layer is preferably 200 mW / cm. 2 It is preferable to do the following: The temperature of the outer surface of the surface layer during ultraviolet irradiation is preferably 40°C or higher, more preferably 80°C or higher, from the viewpoint of keeping the wettability of the outer surface of the surface layer with respect to discharge products within an appropriate range. The cumulative amount of ultraviolet light was set to 5000 mJ / cm in order to sufficiently harden the impregnated acrylic resin and to sufficiently expose the particles containing the inorganic layer compound. 2 The above is preferable.

[0042] <3:Various measurement methods> <3-1: How to confirm the exposure of particles containing inorganic layered compounds> The confirmation that at least a portion of the particles containing the inorganic layered compound is exposed on the outer surface of the surface layer is carried out as follows: A sample piece including the outer surface is cut out from the produced electrophotographic member, and the composition of the outer surface of the sample piece is subjected to XPS analysis using an X-ray spectrophotometer (product name: VersaProbe II, manufactured by ULVAC-PHI, Inc.). The XPS measurement is carried out under the following conditions: X-ray source: Al Kα ray X-ray output: 15KV, 25W Beam diameter: φ100μm Measurement area: 300μm x 300μm

[0043] For quantitative analysis of each element, narrow scan analysis is performed around the bond energy of the element depending on the elemental composition of the inorganic layered compound having ion exchange capacity, and quantification is performed from the peak intensity. For example, when hydrotalcite containing magnesium and aluminum is used as the inorganic layered compound having ion exchange capacity, C 1S (280-294 eV), N 1S (392-406 eV), O 1S (526-538eV), Mg 2p (44-60 eV), Al 2p The elemental concentrations (%) of C, N, O, Mg, and Al are determined using the (68-84 eV) peak. The threshold for peak detection is 0.1%, and if the elemental concentration is less than 0.1%, the peak will be buried in background noise and will be indistinguishable. If the above procedure detects elemental concentrations of Mg and Al, which are derived from hydrotalcite, of 0.1% or more, it is determined that hydrotalcite is exposed on the outer surface of the surface layer.

[0044] <3-2: Elasticity measurement method> The elastic modulus of the surface layer is measured using a scanning probe microscope (SPM) as follows. First, a cross-sectional region of the electrophotographic member where the elastic modulus is to be measured is cut into a thin section using a diamond knife with a cryomicrotome (product name: EMFC6, manufactured by Leica Microsystems) while maintaining the temperature at -110°C. A sample measuring 100 μm square and 100 μm wide in the depth direction is then prepared from the thin section. FIG. 4 shows a schematic cross-sectional view of a surface layer 202 formed on a conductive substrate 201. In this disclosure, as shown in FIG. 4, the first region 203 is defined as a region extending from the outer surface A of the surface layer 202 to a depth of 0.1 μm, and the second region 204 is defined as a region extending from the outer surface A of the surface layer 202 to a depth of 1.0 μm to 1.1 μm. The elastic modulus of the matrix containing a cross-linked polyurethane resin as a binder is measured in each region appearing in the cross section of the prepared sample. The measurements were performed using an SPM device (product name: MFP-3D-Origin, manufactured by Oxford Instruments) and a probe (product name: AC160, manufactured by Olympus). The force curve was measured 10 times, and the arithmetic mean of the eight points excluding the highest and lowest values ​​was calculated, and the elastic modulus was calculated using Hertz's theory. The elastic moduli of the matrix in the first region 203 and the second region 204 were designated E1 and E2, respectively. In the present disclosure, the elastic modulus E1 of the matrix measured in the first region is 200 MPa or more, and the elastic modulus E2 of the matrix measured in the second region is preferably 10 MPa or more and 200 MPa or less.

[0045] <3-3: Contact angle measurement method> In the measurement of the contact angle using a 0.1 mol / L aqueous solution of sodium nitrate on the outer surface of the surface layer of the electrophotographic member of the present disclosure, a 1 μL droplet of the aqueous solution is deposited on the outer surface, and the contact angle after 1 second from the deposition is measured as θ A (°), and the contact angle 60 seconds after the droplet was applied was θ B (°), then θ A and θ B It is preferable that satisfies the following (Formula 1) to (Formula 3). (Formula 1):θ A ≧95.0(°) (Formula 2):θ B ≦95.0(°) (Formula 3):θ A -θ B ≧10.0(°) where θ A is an index showing the difficulty of the discharge products penetrating into the outer surface of the surface layer. A When (Equation 1) is satisfied, the outer surface of the surface layer can sufficiently suppress the penetration of discharge products. B is an index showing whether the outer surface of the surface layer has the ability to diffuse discharge products. B When satisfies (Equation 2), the outer surface of the surface layer has sufficient ability to diffuse discharge products. A -θ B is an index that represents the speed at which discharge products diffuse on the outer surface of the surface layer. A -θ B The larger the value of θ, the faster the diffusion speed of the discharge products. A -θ B It is preferable that satisfies (Equation 3). The contact angle can be measured using a contact angle meter DM-501 (trade name, manufactured by Kyowa Interface Science Co., Ltd.). The measurement is carried out in an environment of a temperature of 23°C and a relative humidity of 50%RH. In the measurement, a 1 μL droplet of a 0.1 mol / L aqueous solution of sodium nitrate is deposited on the outer surface of the electrophotographic member, and the contact angle θ after 1 second from the deposition is measured. A , and the contact angle θ after 60 seconds of droplet deposition B Record the following.

[0046] [Method for manufacturing electrophotographic members] As described above, the method for producing an electrophotographic member according to one embodiment of the present disclosure is characterized in that the surface layer is formed by a method including the following steps (i) to (iii): (i) a step of applying a coating material for forming a crosslinked polyurethane resin layer, which contains a polyol, an isocyanate compound, and particles containing an inorganic layered compound having ion exchange ability, onto a conductive substrate, and drying and solidifying or heat-curing the coating material to form a crosslinked polyurethane resin layer; (ii) a step of impregnating the crosslinked polyurethane resin layer with an impregnation treatment liquid containing a (meth)acrylic monomer, and then polymerizing and curing the (meth)acrylic monomer to form a surface layer having an interpenetrating polymer network structure in which the crosslinked polyurethane resin is interpenetrated with the crosslinked acrylic resin; and (iii) A step of exposing at least a part of the particles containing the inorganic layered compound to the outer surface of the surface layer by performing an ultraviolet irradiation treatment.

[0047] [Process cartridge] FIG. 2 is a schematic cross-sectional view showing a process cartridge according to one embodiment of the present disclosure. The process cartridge 100 shown in FIG. 2 is configured to be detachably mountable to the main body of an electrophotographic image forming apparatus. The process cartridge 100 includes a developing chamber 102 having an opening facing a photoconductor 101. A toner container 104 containing toner 103 is disposed at the rear of the developing chamber 102. A transport member 107 for transporting the toner 103 to the developing chamber 102 is disposed in the toner container 104 as needed. The opening connecting the developing chamber 102 and the toner container 104 is separated by a seal member 105, which is removed when the process cartridge 100 is first used. The developing chamber 102 is also provided with a developing roller 106, a toner supply roller 108, a developing blade 109, and a toner blowout prevention sheet 110. The toner 103 is applied to the developing roller 106 by the toner supply roller 108. The developing roller 106 rotates in the direction indicated by the arrow in the figure, and the toner 103 carried by this developing roller 106 is regulated to a predetermined layer thickness by a developing blade 109, and then sent to a developing area facing the photosensitive member 101. In addition to the above configuration, the process cartridge 100 also includes a charging roller 111, a cleaning blade 112, and a waste toner container 119.

[0048] [Electrophotographic image forming device] The electrophotographic image forming apparatus (electrophotographic apparatus) according to this embodiment has an image carrier for carrying an electrostatic latent image and a member that contacts the image carrier, and is characterized in that the member that contacts the image carrier is an electrophotographic member according to this disclosure. The member that contacts the image carrier can be at least one member selected from the group consisting of a charging member, a developing member, a transfer member, and a cleaning member. Figure 3 is a schematic cross-sectional view showing an electrophotographic apparatus according to one embodiment of this disclosure. This electrophotographic apparatus can be used by mounting the process cartridge 100 shown in Figure 2. The printing operation of the electrophotographic apparatus will be described below. The photoconductor 101, which serves as an image carrier, is uniformly charged by a charging roller 111 connected to a bias power supply (not shown). Next, an electrostatic latent image is formed on the surface of the photoconductor 101 by exposure light 113 for writing the electrostatic latent image. Either LED light or laser light can be used as the exposure light 113. Next, a negatively charged toner is applied (developed) to the electrostatic latent image by a developing roller 106 housed in a process cartridge 100 that is detachably attached to the main body of the electrophotographic apparatus. Next, a toner image is formed on the photoconductor 101, and the electrostatic latent image is converted into a visible image. At this time, a voltage is applied to the developing roller 106 by a bias power supply (not shown). The toner image developed on the photoconductor 101 is primarily transferred to an intermediate transfer belt 114. A primary transfer member 115 abuts against the back surface of the intermediate transfer belt 114, and by applying a voltage to the primary transfer member 115, a negative polarity toner image is primarily transferred from the photosensitive member 101 to the intermediate transfer belt 114. The primary transfer member 115 may be in the form of a roller or a blade. 3, a total of four process cartridges 100, one each containing yellow, cyan, magenta, and black toner, are detachably mounted in the main body of the electrophotographic apparatus. The above-mentioned charging, exposure, development, and primary transfer processes are performed sequentially with a predetermined time difference, and a state in which four color toner images are superimposed on the intermediate transfer belt 114 to represent a full-color image is created. As the intermediate transfer belt 114 rotates, the toner image on the intermediate transfer belt 114 is transported to a position facing a secondary transfer member 116. At this time, recording paper, which is a transfer material, is transported between the intermediate transfer belt 114 and the secondary transfer member 116 at a predetermined timing along a recording paper transport route 117. Then, by applying a secondary transfer bias to the secondary transfer member 116, the toner image on the intermediate transfer belt 114 is transferred to the recording paper. The recording paper onto which the toner image has been transferred by the secondary transfer member 116 is transported to a fixing device 118, where the toner image on the recording paper is melted and fixed on the recording paper. The recording paper is then ejected from the electrophotographic device, completing the printing operation. Note that any toner image remaining on the photoreceptor 101 without being transferred from the photoreceptor 101 to the intermediate transfer belt 114 is scraped off by a cleaning blade 112 and stored in a waste toner storage container 119. In the process cartridge shown in FIG. 2 and the electrophotographic device shown in FIG. 3, electrophotographic members according to the present disclosure can be used, for example, as a charging roller 111 as a charging member, a developing roller 106 as a developing member, an intermediate transfer belt 114 as a transfer member, and a cleaning blade 112 as a cleaning member. [Example]

[0049] Hereinafter, several aspects of the present disclosure will be described in more detail using specific examples of a developing roller as an example, but the technical scope of the present disclosure as an electrophotographic member is not limited to these specific aspects.

[0050] <Preparation of coating material for forming crosslinked polyurethane resin layer> [Preparation of paint A1] 100 parts by weight of polyether polyol (trade name: PTGL-1000, manufactured by Hodogaya Chemical Co., Ltd.), 40 parts by weight of polymeric MDI (trade name: Millionate MR-400, manufactured by Tosoh Corporation), 1 part by weight of modified silicone oil (trade name: TSF4445, manufactured by Momentive Performance Materials Japan Co., Ltd.), 35 parts by weight of carbon black (trade name: SUNBLACK X15, manufactured by Asahi Carbon Co., Ltd.), 20 parts by weight of roughening agent (trade name: Dimic Beads UCN-5150, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and 35 parts by weight of hydrotalcite (trade name: DHT-4A, manufactured by Kyowa Chemical Industry Co., Ltd.) were weighed out, and methyl ethyl ketone (manufactured by Kishida Chemical Co., Ltd.) was added to a solids concentration of 30% by weight, followed by stirring and mixing. This mixture was uniformly dispersed using a sand mill to obtain Paint A1.

[0051] [Preparation of paints A2 to A7] Paints A2 to A7 with a solid content of 30 mass % were obtained in the same manner as paint A1, except that the blending amounts of each material were changed as shown in Table 1.

[0052] [Table 1]

[0053] <Preparation of paint for acrylic monomer impregnation treatment> [Preparation of paint B1] Five parts by mass of acrylic monomer (trade name: EBECRYL145, manufactured by Daicel-Allnex Co., Ltd.), 0.5 parts by mass of polymerization initiator (trade name: Omnirad184, manufactured by IGM Resins Co., Ltd.), and 94.5 parts by mass of methyl ethyl ketone (manufactured by Kishida Chemical Co., Ltd.) as a solvent were dissolved and mixed to obtain impregnation treatment paint B1.

[0054] [Preparation of paint B2] Paint B2 was obtained in the same manner as Paint B1, except that the polymerization initiator was changed as shown in Table 2.

[0055] [Table 2]

[0056] [Example 1] <Preparation of conductive substrate> A primer (product name: DY35-051, manufactured by Dow Corning Toray Co., Ltd.) was applied to a stainless steel (SUS304) core bar with an outer diameter of 6 mm and a length of 270 mm, and the core bar was heated at a temperature of 150°C for 20 minutes. This core bar was placed concentrically in a cylindrical mold with an inner diameter of 12.0 mm. The intermediate layer material was an addition-curable silicone rubber composition obtained by mixing the materials shown in Table 3 below in a kneader (product name: Trimix TX-15, manufactured by Inoue Seisakusho Co., Ltd.), and then poured into a mold heated to 120°C. After pouring the composition, it was heat-molded at 120°C for 10 minutes, cooled to room temperature, and then demolded from the mold, yielding a conductive substrate (elastic roller) with a 3.0 mm-thick intermediate layer formed on the outer periphery of a core metal.

[0057] [Table 3]

[0058] <Formation of surface layer> The elastic roller was dip-coated with the crosslinked polyurethane resin layer-forming paint A1, and then heated at 135°C for 120 minutes to form a 15µm-thick resin layer on the elastic roller. The elastic roller with the resin layer formed thereon was then immersed in the acrylic monomer impregnation treatment paint B1 for 5 seconds to impregnate the resin layer with the acrylic monomer. The elastic roller was then heated at 90°C for 1 hour to volatilize the solvent. The impregnated elastic roller was subjected to ultraviolet irradiation treatment by the following method. While rotating the impregnated elastic roller, it was irradiated with a high-pressure mercury lamp (product name: handy type UV curing device, manufactured by Mario Network Co., Ltd.). This polymerized and cured the acrylic monomer, and at the same time, the hydrotalcite surface was exposed, thereby obtaining a developing roller 1. The ultraviolet light had an illuminance of 125 mW / cm. 2It was irradiated for 120 seconds, and the ambient temperature during irradiation was set to 80°C. The total mass of the surface layer produced by the above method was 250 mg, and the increase in mass after impregnation of the acrylic resin into the resin layer was 2 mg. In this way, the following evaluations were performed on the obtained developing roller 1.

[0059] <Confirmation of exposure of particles containing inorganic layered compounds by XPS> By the XPS analysis method described above, the elemental concentrations (%) of magnesium and aluminum on the outer surface of the developing roller 1 were calculated, and the exposure of particles containing inorganic layered compounds was confirmed. The obtained results are shown in Table 4-1.

[0060] <Measurement of elastic modulus by SPM> By the elastic modulus measurement method using the SPM described above, the elastic moduli E1 and E2 of the first region and the second region were determined. The obtained results are shown in Table 4-1.

[0061] <Measurement of contact angle> By the contact angle measurement method described above, the contact angle θ after 1 second of droplet deposition on the outer surface of the developing roller 1 with respect to a 0.1 mol / L aqueous sodium nitrate solution A and the contact angle θ after 60 seconds of droplet deposition B were determined. The obtained results are shown in Table 4-1.

[0062] <Image flow evaluation> Image flow is an image defect caused by a decrease in the resistance of the outer surface of the photoreceptor due to the accumulation of discharge products. In a photoreceptor with a decreased outer surface resistance, the latent image collapses because the charges formed by exposure move on the low-resistance outer surface. Due to this collapse of the latent image, there may be a situation where the areas that should be developed by toner are not developed and become white. This white defect is called image flow. Discharge products promote a decrease in the resistance of the photoreceptor surface by combining with moisture in the atmosphere. Therefore, image flow is likely to occur especially in a high-temperature and high-humidity environment, and is also likely to occur as the potential of the latent image on the photoreceptor approaches the bright part potential V l (that is, the thinner the density gradation). To confirm the performance of image flow, evaluations were performed according to the following procedure. To reduce the torque of the process cartridge, the cleaning blade of a process cartridge (product name: HP 410X High Yield Magenta Original Laser Jet Toner Cartridge (CF413X), manufactured by Hewlett-Packard) was removed to eliminate the cleaning component. This reduced the torque of the process cartridge while also making it easier for discharge products to accumulate on the photoreceptor surface. Next, the developed roller 1 was incorporated into the process cartridge, and the process cartridge was then loaded into a laser beam printer (product name: Color Laser Jet Pro M452dw, manufactured by Hewlett-Packard), an image forming apparatus. The laser beam printer was aged for at least 24 hours in a high-temperature, high-humidity environment (temperature: 30°C, relative humidity: 80%). After the aging process, 4,000 images with a print rate of 1% were printed on recording paper in the same environment. After that, a horizontal gradation image (a horizontal band of 40mm width with five gradation levels, starting from the top of the page: 0%, 25%, 50%, 75%, and 100% density) was printed. The printed horizontal gradation image was evaluated for image flow using the following evaluation criteria. The results are shown in Table 4-1. Ranks A to D are acceptable levels, and rank E is unacceptable. Rank A: No white spots in all gradations from 25% density to 100% density. Rank B: White spots are observed at a density of 25%. Rank C: White spots are observed in the gradation range from 25% density to 50% density. Rank D: White spots are observed in the gradation range from 25% density to 75% density. Rank E: White spots are observed in the gradation range from 25% density to 100% density.

[0063] [Example 2] In the ultraviolet irradiation treatment, the illuminance was set to 60mW / cm 2 Developing roller 2 was produced in the same manner as in Example 1, except for changing the above. The resulting developing roller 2 was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 4-1.

[0064] [Example 3] Developing roller 3 was produced in the same manner as in Example 1, except that the ambient temperature during ultraviolet irradiation treatment was changed to 40° C. The resulting developing roller 3 was evaluated in the same manner as in Example 1. The results are shown in Table 4-1.

[0065] [Example 4] In the ultraviolet irradiation treatment, the illuminance was set to 60mW / cm 2 Developing roller 4 was produced in the same manner as in Example 1, except that the temperature was changed to 40° C. and the ambient temperature during irradiation was changed to 40° C. The resulting developing roller 4 was evaluated in the same manner as in Example 1. The results are shown in Table 4-1.

[0066] [Example 5] A developing roller 5 was produced in the same manner as in Example 4, except that paint B2 was used as the paint for the acrylic monomer impregnation treatment and the heat treatment conditions after the impregnation treatment were 70°C and 0.5 hours. The resulting developing roller 5 was evaluated in the same manner as in Example 1. The results are shown in Table 4-1. In this example, paint B2 containing ACVA as the polymerization initiator was used, and the heat treatment after the impregnation treatment completed the polymerization and curing of the acrylic monomer.

[0067] [Example 6] Developing roller 6 was produced in the same manner as in Example 5, except that the heat treatment conditions after the impregnation treatment were set to 70°C for 1 hour. The resulting developing roller 6 was evaluated in the same manner as in Example 1. The results are shown in Table 4-1.

[0068] [Example 7] Developing roller 7 was produced in the same manner as in Example 6, except that paint A2 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 7 was evaluated in the same manner as in Example 1. The results are shown in Table 4-1.

[0069] [Example 8] Developing roller 8 was produced in the same manner as in Example 6, except that paint A3 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 8 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2.

[0070] [Example 9] Developing roller 9 was produced in the same manner as in Example 1, except that paint A4 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 9 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2. In this example, lithium aluminum oxide was used as the inorganic layered compound, so the elemental concentrations of lithium and aluminum on the outer surface of the developing roller were calculated by XPS analysis, and exposure of particles containing the inorganic layered compound was confirmed.

[0071] [Example 10] A developing roller 10 was produced in the same manner as in Example 1, except that paint A5 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 10 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2. In this example, desautelsite was used as the inorganic layered compound, so the elemental concentrations of magnesium and manganese on the outer surface of the developing roller were calculated by XPS analysis, and the exposure of particles containing the inorganic layered compound was confirmed.

[0072] [Example 11] A developing roller 11 was produced in the same manner as in Example 1, except that paint A6 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 11 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2. In this example, Stitchtite was used as the inorganic layered compound, so the elemental concentrations of magnesium and chromium on the outer surface of the developing roller were calculated by XPS analysis, and the exposure of particles containing the inorganic layered compound was confirmed.

[0073] [Comparative Example 1] A developing roller 12 was produced in the same manner as in Example 1, except that the acrylic monomer impregnation treatment, the heat treatment after the impregnation treatment, and the ultraviolet irradiation treatment were not performed. The resulting developing roller 12 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2.

[0074] Comparative Example 2 A developing roller 13 was produced in the same manner as in Example 1, except that the acrylic monomer impregnation treatment and the heat treatment after the impregnation treatment were not performed. The resulting developing roller 13 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2.

[0075] Comparative Example 3 A developing roller 14 was produced in the same manner as in Example 1, except that paint A7 was used as the paint for forming the crosslinked polyurethane resin layer. The resulting developing roller 14 was evaluated in the same manner as in Example 1. The results are shown in Table 4-2.

[0076] [Table 4-1]

[0077] [Table 4-2]

[0078] As shown in Tables 4-1 and 4-2, the developing rollers according to Examples 1 to 11 of the present disclosure were found to be able to suppress image deletion even when used in a laser beam printer without a cleaning member. In particular, the developing rollers according to Examples 1 to 3, which used hydrotalcite as the inorganic layered compound having ion exchange capacity and in which the elastic modulus and contact angle of the surface layer were within predetermined ranges, were able to suppress image deletion to a higher degree. On the other hand, the developing rollers according to Comparative Examples 1 and 2, which had an elastic modulus E1 of less than 200 MPa, and the developing roller according to Comparative Example 3, which did not contain an inorganic layered compound having ion exchange capacity, were unable to achieve the effect of suppressing image deletion.

[0079] The present disclosure includes the following configurations. [Configuration 1] An electrophotographic member having a conductive substrate and a single surface layer on the substrate, the surface layer has a matrix containing a crosslinked resin as a binder; the surface layer holds particles containing an inorganic layered compound having ion exchange capacity such that at least a portion of the particles is exposed from the outer surface of the surface layer; an electrophotographic member, wherein the modulus of elasticity of the matrix measured in a region from the outer surface of the surface layer to a depth of 0.1 μm in a cross section in the thickness direction of the surface layer is 200 MPa or more; [Configuration 2] 2. The electrophotographic member according to claim 1, wherein the matrix has an interpenetrating polymer network structure in which a crosslinked acrylic resin interpenetrates a crosslinked polyurethane resin. [Configuration 3] 3. The electrophotographic member according to claim 2, wherein at least a portion of the outer surface of the surface layer is composed of the matrix having the interpenetrating polymer network structure. [Configuration 4] 4. The electrophotographic member according to any one of configurations 1 to 3, wherein the inorganic layered compound having ion exchange ability is a hydrotalcite compound. [Configuration 5] 5. The electrophotographic member according to claim 4, wherein the content of the hydrotalcite compound in the surface layer is 1% by mass or more and 40% by mass or less with respect to the total mass of the surface layer. [Configuration 6] 6. The electrophotographic member according to any one of configurations 1 to 5, wherein the elastic modulus of the matrix measured in a region of the surface layer from the outer surface to a depth of 1.0 μm to 1.1 μm is 10 MPa or more and 200 MPa or less. [Configuration 7] In the contact angle measurement using a 0.1 mol / L sodium nitrate aqueous solution on the outer surface of the surface layer, a 1 μL droplet of the aqueous solution was dropped onto the outer surface, and the contact angle after 1 second from the drop was measured as θ A (°), and the contact angle 60 seconds after the droplet was applied was θ B (°), then θ A and θB The electrophotographic member according to any one of configurations 1 to 6, which satisfies the following (Formula 1) to (Formula 3): (Formula 1):θ A ≧95.0 (Formula 2):θ B ≦95.0 (Formula 3):θ A -θ B ≧10.0. [Configuration 8] A method for producing an electrophotographic member according to any one of configurations 1 to 7, A method for producing an electrophotographic member, wherein the surface layer is formed by a method including the following steps (i) to (iii): (i) a step of applying a coating material for forming a crosslinked polyurethane resin layer, which contains a polyol, an isocyanate compound, and particles containing an inorganic layered compound having ion exchange ability, onto a conductive substrate, and drying and solidifying or heat-curing the coating material to form a crosslinked polyurethane resin layer; (ii) a step of impregnating the crosslinked polyurethane resin layer with an impregnation treatment liquid containing a (meth)acrylic monomer, and then polymerizing and curing the (meth)acrylic monomer to form a surface layer having an interpenetrating polymer network structure in which the crosslinked polyurethane resin is interpenetrated with the crosslinked acrylic resin; (iii) A step of exposing at least a part of the particles containing the inorganic layered compound to the outer surface of the surface layer by performing an ultraviolet irradiation treatment. [Configuration 9] A process cartridge configured to be detachably mountable to the main body of an electrophotographic image forming apparatus, the process cartridge comprising the electrophotographic member according to any one of Configurations 1 to 7. [Configuration 10] An electrophotographic image forming apparatus having an image carrier for carrying an electrostatic latent image and a member in contact with the image carrier, wherein the member in contact with the image carrier is the electrophotographic member according to any one of Configurations 1 to 7. [Explanation of symbols]

[0080] 1: Electrophotographic roller 2: Core body 3: Surface layer 203: First Area

Claims

1. An electrophotographic member having a conductive substrate and a single surface layer on the substrate, the surface layer has a matrix containing a crosslinked resin as a binder; the surface layer holds particles containing an inorganic layered compound having ion exchange capacity such that at least a portion of the particles is exposed from the outer surface of the surface layer; an elastic modulus of the matrix measured in a region of the surface layer from the outer surface to a depth of 0.1 μm in a cross section in the thickness direction of the surface layer is 200 MPa or more;

2. 2. An electrophotographic member according to claim 1, wherein said matrix has an interpenetrating polymer network structure in which a crosslinked acrylic resin interpenetrates a crosslinked polyurethane resin.

3. 3. An electrophotographic member according to claim 2, wherein at least a portion of said outer surface of said surface layer is comprised of said matrix having said interpenetrating polymer network structure.

4. 2. The electrophotographic member according to claim 1, wherein the inorganic layered compound having ion exchange ability is a hydrotalcite compound.

5. 5. The electrophotographic member according to claim 4, wherein the content of the hydrotalcite compound in the surface layer is 1% by mass or more and 40% by mass or less with respect to the total mass of the surface layer.

6. 2. The electrophotographic member according to claim 1, wherein the elastic modulus of the matrix measured in a region of the surface layer from the outer surface to a depth of 1.0 μm to 1.1 μm is 10 MPa or more and 200 MPa or less.

7. In the contact angle measurement using a 0.1 mol / L aqueous solution of sodium nitrate on the outer surface of the surface layer, a 1 μL droplet of the aqueous solution was dropped onto the outer surface, and the contact angle after 1 second from the drop was measured as θ Ａ (°), and the contact angle 60 seconds after the droplet was applied was θ Ｂ (°), then θ Ａ and θ Ｂ The electrophotographic member according to claim 1, wherein the following formulas (1) to (3) are satisfied: (Equation 1): θ Ａ ≧95.0 (Equation 2): θ Ｂ ≦95.0 (Formula 3): θ Ａ -θ Ｂ ≧10.0

8. A method for producing an electrophotographic member according to any one of claims 1 to 7, A method for producing an electrophotographic member, characterized in that the surface layer is formed by a method including the following steps (i) to (iii): (i) forming a crosslinked polyurethane resin layer by applying a coating material for forming a crosslinked polyurethane resin layer, which coating material contains a polyol, an isocyanate compound, and particles containing an inorganic layered compound having ion exchange ability, onto a conductive substrate, and then drying and solidifying the coating material or heat-curing the coating material; (ii) a step of impregnating the crosslinked polyurethane resin layer with an impregnation treatment liquid containing a (meth)acrylic monomer, and then polymerizing and curing the (meth)acrylic monomer to form a surface layer having an interpenetrating polymer network structure in which the crosslinked polyurethane resin is interpenetrated with the crosslinked acrylic resin; (iii) A step of exposing at least a part of the particles containing the inorganic layered compound to the outer surface of the surface layer by performing an ultraviolet irradiation treatment.

9. 8. A process cartridge configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, comprising the electrophotographic member according to claim 1.

10. An electrophotographic image forming apparatus having an image carrier for carrying an electrostatic latent image and a member in contact with the image carrier, wherein the member in contact with the image carrier is the electrophotographic member according to any one of claims 1 to 7.

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