Developing roller

Abstract

Provided is a developing roller which can suppress toner leakage and fogging and is also excellent in stability of image density. The developing roller includes a shaft member, an intermediate layer disposed radially outward of the shaft member, and a surface layer at an outermost position. The intermediate layer contains an aggregate A formed of particles dispersed in a resin. The surface layer contains particles B dispersed in a resin, and the particles B are at least one selected from the group consisting of particles and aggregates formed from the particles. The granular body (B) has an average diameter dB of not less than 1 [mu] m and not more than 10 [mu] m.

Description

Technical Field

[0001] This disclosure relates to a developing roller. Background Technology

[0002] In electrophotographic image forming apparatuses such as copiers and printers, a development method is typically employed in which toner is supplied to a photosensitive drum carrying a latent image, and the toner is attached to the latent image on the photosensitive drum to make the latent image visible. Specifically, in this development method, development is performed, for example, by charging the photosensitive drum to a certain potential, forming an electrostatic latent image on the photosensitive drum using an exposure tool, bringing a developing roller carrying toner into contact with the photosensitive drum carrying the electrostatic latent image, and attaching toner to the latent image on the photosensitive drum.

[0003] The aforementioned developing roller typically has a structure in which an elastic layer is formed on the outer periphery of the shaft member. This elastic layer is formed from a semi-conductive elastomer in which a conductive agent is dispersed in an elastomer (such as polyurethane) or from a foam formed by foaming these materials. The shaft member is mounted such that its two longitudinal ends are supported by a shaft. Furthermore, there are cases in the aforementioned developing roller where a surface layer made of resin or the like is formed on the outside of the elastic layer, intended for purposes such as controlling the charging and adhesion characteristics of the toner and preventing contamination of the photosensitive drum (for example, see Patent Document 1).

[0004] There are also cases where minute particles are mixed in the layer (including the aforementioned surface layer) arranged radially outside the developing roller to create an uneven surface. For example, Patent Document 2 discloses increasing the toner supply capacity by providing one or more resin layers radially outside the shaft member formed of a metal tube and by dispersing minute particles in at least one of the resin layers to create surface roughness.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2005-352072

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-065188 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] When considering the surface roughness (unevenness) of the developing roller, the protrusion height of the surface is set to a minimum to suppress damage to components in contact with the developing roller (such as the developing blade) and to prevent toner leakage from the end sealing components of the image forming apparatus. Such a protrusion height can be set at a high level by forming a layer in which tiny particles of relatively large particle size are mixed.

[0011] However, when using microparticles with large particle sizes, it is difficult to disperse the microparticles evenly in the layer, and uneven delivery of toner and image fogging may occur during development.

[0012] In contrast, using tiny particles with relatively small particle sizes allows for uniform dispersion. However, in this case, the height (protrusion height) is insufficient, meaning that adequate space cannot be provided between the surface of the developing roller and contact components such as the developing blade, and malfunctions such as toner leakage may occur. In other words, toner leakage and atomization are essentially opposites.

[0013] Furthermore, when the microparticles used are hard, they are prone to detaching in their original form during continuous or long-term operation of the image forming apparatus, and there is concern that changes in image density due to significant changes in roughness may occur in such cases.

[0014] Therefore, this disclosure solves the problem of providing a developing roller that can suppress toner leakage and fogging and also has excellent stability in image density.

[0015] Solution for solving the problem

[0016] Specifically, the main structure of the developing roller according to this disclosure, which solves the above problems, is as follows.

[0017] [1] A developing roller, comprising:

[0018] Shaft components;

[0019] An intermediate layer, the intermediate layer being disposed radially outside the shaft member; and

[0020] Surface layer, wherein the surface layer is located at the outermost position,

[0021] The intermediate layer comprises aggregates A formed of particles dispersed in the resin, and

[0022] The surface layer comprises granular particles B dispersed in the resin, wherein the granular particles B are selected from at least one type selected from particles and aggregates formed from particles, and wherein the granular particles B have an average diameter d of not less than 1 μm and not greater than 10 μm. B .

[0023] [2] According to the developing roller of [1], wherein the aggregate A in the intermediate layer has an average diameter d of not less than 10 μm and not more than 35 μm. A .

[0024] [3] According to the developing roller of [1] or [2], wherein the content of the particles in the intermediate layer is not less than 10 parts by mass and not more than 30 parts by mass relative to 100 parts by mass of the resin.

[0025] [4] The developing roller according to any one of [1] to [3], wherein the content of the particles in the surface layer is not less than 15 parts by mass and not more than 35 parts by mass relative to 100 parts by mass of the resin.

[0026] [5] The developing roller according to any one of [1] to [4], wherein the average diameter d of the aggregate A is d A It is greater than the thickness of the intermediate layer.

[0027] [6] The developing roller according to any one of [1] to [5], wherein the average diameter d of the granules B is d B It is greater than the thickness of the surface layer.

[0028] [7] The developing roller according to any one of [1] to [6] further includes an elastic layer between the shaft member and the intermediate layer.

[0029] [8] The developing roller according to any one of [1] to [7] further includes an outer intermediate layer between the intermediate layer and the surface layer.

[0030] The effects of the invention

[0031] According to this disclosure, a developing roller can be provided that can suppress toner leakage and fogging, and also has excellent stability in image density. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of a developing roller according to one embodiment of the present disclosure. Detailed Implementation

[0033] (Developing roller)

[0034] The following provides a detailed description of a developing roller according to embodiments of the present disclosure.

[0035] Figure 1 This is a cross-sectional view of a developing roller (hereinafter also referred to as "the developing roller of this embodiment") according to one embodiment of the present disclosure. Figure 1 The developing roller 1 shown includes a shaft member 2, an elastic layer 3 arranged radially outward of the shaft member 2, an intermediate layer 4 arranged radially outward of the elastic layer 3, and a surface layer 5 arranged radially outward of the intermediate layer 4. It should be noted that the elastic layer 3 is not an essential component of the developing roller according to this disclosure. It should also be noted that, although... Figure 1The developing roller 1 shown includes only one elastic layer 3, but the developing roller according to this disclosure may include two or more elastic layers.

[0036] The developing roller 1 of this embodiment is characterized in that the intermediate layer 4 comprises aggregates A formed of particles dispersed in resin, the surface layer 5 comprises granular bodies B dispersed in resin, wherein the granular bodies B are at least one selected from particles and aggregates formed of particles, and the average diameter d of the granular bodies B is... B Not less than 1 μm and not more than 10 μm. Note that in Figure 1 Illustrations of particles and aggregates are omitted.

[0037] The intermediate layer 4 of the developing roller 1 in this embodiment has aggregates A dispersed therein as described above. The aggregates mentioned herein generally have at least a certain size. Therefore, the aggregates A in the intermediate layer 4 create an appropriate degree of unevenness (appropriate high protrusions) on the outer peripheral surface of the developing roller 1, thereby suppressing toner leakage and also suppressing damage to components (developing blades, etc.) in contact with the developing roller.

[0038] Furthermore, by employing aggregates as the dispersion medium in the intermediate layer 4, even during continuous or long-term operation of the image forming apparatus including the developing roller 1, it is possible to limit the aggregates A to only partially detaching without overall separation. Therefore, significant changes in surface roughness can be suppressed, and image density stability can be maintained.

[0039] Furthermore, the surface layer 5 of the developing roller 1 in this embodiment contains granular particles with relatively small particle sizes, more specifically, particles with an average diameter d as described above. B The particles B are 10 μm or smaller. Since using particles with relatively small particle sizes in this way can achieve even more uniform dispersion, setting a layer containing the aforementioned particles B as a surface layer can suppress image haze during development.

[0040] Therefore, the developing roller 1 of this embodiment can suppress toner leakage and fogging, and also excels in the stability of image density.

[0041] <Shaft Components>

[0042] The developing roller 1 of this embodiment includes the shaft member 2 as described above. The shaft member 2 is preferably a component with good electrical conductivity. Specifically, for example, the material of the shaft member 2 can be a metal such as iron, stainless steel, aluminum, or any alloy thereof, or a plastic with good electrical conductivity. Furthermore, the shaft member 2 can be a solid material or a hollow material (tube). Additionally, the shaft member 2 can include shaft portions forming the two longitudinal ends of the shaft member 2, such that the shaft member 2 is axially supported by the roller support portion of the image forming apparatus.

[0043] <Intermediate Layer>

[0044] As described above, the developing roller 1 of this embodiment includes an intermediate layer 4 disposed radially outside the shaft member 2. The intermediate layer 4 contains aggregates A formed of particles dispersed in the resin.

[0045] The resin constituting the intermediate layer 4 can be, for example, a UV-curable resin, an electron beam-curable resin, etc., without any specific limitations. Specifically, the resin can be polyester resin, polyether resin, fluororesin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic polyurethane resin, polyurethane resin, alkyd resin, phenolic resin, melamine resin, urea-formaldehyde resin, silicone resin, polyvinyl butyral resin, etc. One of these resins can be used alone, or two or more of these resins can be used in combination. Among these resins, a UV-curable resin is preferred, and a polyurethane resin (UV-curable polyurethane resin) is more preferred as the constituting resin of the intermediate layer 4. Note that the polyurethane resin is formed by the reaction of a polyol component and a polyisocyanate component and has the property of being cured by heat.

[0046] The intermediate layer 4 needs to have aggregates A formed of particles dispersed therein. When non-aggregates are used as the dispersion medium, the overall separation of the non-aggregates occurs during continuous or long-term operation of the image forming apparatus including the developing roller 1, and the stability of the image density is poor.

[0047] The constituent particles of aggregate A dispersed in intermediate layer 4 can be particles of organic materials, such as silicone rubber, acrylic resins, styrene resins, acrylic / styrene copolymers, fluoropolymers (polytetrafluoroethylene (PTFE), etc.), polyurethane elastomers, polyurethane acrylates, melamine resins, or phenolic resins, without any specific limitations. One of these types of particles can be used alone, or two or more of these types of particles can be used in combination. In these examples, from the viewpoint of aggregateability and availability, fluoropolymers are preferred as constituent particles of aggregate A.

[0048] The deformation strength (σ) of the constituent particles of aggregate A dispersed in intermediate layer 4 10% The preferred strength is 1 MPa or less. When the deformation strength (σ) of the particles... 10% When the pressure is 1 MPa or less, damage to the photosensitive drum is suppressed, and atomization can be suppressed more effectively.

[0049] Note the deformation strength (σ) of the particles. 10% The deformation strength is the deformation strength at 10% compressive displacement of the particle size, and can be measured by the procedure described in the Examples section.

[0050] The average diameter d of aggregate A dispersed in intermediate layer 4 A Preferably, the diameter is not less than 10 μm and not greater than 35 μm. When the average diameter d... A When the diameter is 10 μm or larger, the effect of suppressing toner leakage can be further enhanced, and the image density stability can be maintained for a longer period of time. Furthermore, when the average diameter d... A When the diameter is 35 μm or smaller, image density inhomogeneity can be suppressed, and the effect of suppressing fogging can be further enhanced. From a similar perspective, the average diameter d of aggregate A... A More preferably, it is 15 μm or larger, and even more preferably, it is 30 μm or smaller.

[0051] Note the average diameter d of aggregate A. A Measurements can be made using the procedures described in the Examples section.

[0052] The average diameter d of aggregate A dispersed in intermediate layer 4 A Preferably, the thickness (resin thickness) is greater than that of the intermediate layer 4. In other words, when coating the resin composition comprising resin and aggregate A to form the intermediate layer 4, it is preferable to coat the resin composition to a thickness that causes the aggregate A portion to protrude. This makes the unevenness at the outer peripheral surface of the developing roller 1 more pronounced and can more effectively suppress toner leakage. Note that, for example, the actual thickness (resin thickness) of the intermediate layer 4 can be set to be not less than 2 μm and not more than 10 μm.

[0053] The diameter of the constituent particles of aggregate A (i.e., the average primary particle size) is preferably not less than 0.1 μm and not more than 1 μm. When the average primary particle size is 0.1 μm or greater, this facilitates the gradual shedding of aggregate A during continuous or long-term operation of the image forming apparatus including the developing roller 1, and better maintains the stability of image density. Furthermore, when the average primary particle size is 1 μm or less, the desired aggregate A is more easily formed.

[0054] The particle content in the intermediate layer 4 is preferably not less than 10 parts by weight and not more than 30 parts by weight relative to 100 parts by weight of resin. When the content is 10 parts by weight or more, the density of aggregate A is sufficiently high, and the effect of suppressing toner leakage can be further enhanced. In addition, when the content is 30 parts by weight or less, coating unevenness during the production of intermediate layer 4 can be suppressed. From a similar point of view, the particle content in the intermediate layer 4 is more preferably 15 parts by weight or more relative to 100 parts by weight of resin, and more preferably 25 parts by weight or less relative to 100 parts by weight of resin.

[0055] In addition to the resin and the aggregate A formed from particles, the intermediate layer 4 may contain other components such as conductive agents.

[0056] <Surface Layer>

[0057] As described above, the developing roller 1 of this embodiment includes a surface layer 5 at its outermost position. The surface layer 5 contains granular particles B dispersed in a resin, wherein the granular particles B are at least one selected from particles and aggregates formed from particles.

[0058] There are no specific limitations on the resin constituting the surface layer 5, and it can be any of those resins previously described as constituting the intermediate layer 4. One of these resins can be used alone, or two or more of these resins can be used in combination. Among these resins, a UV-curable resin is preferred, and a polyurethane resin (UV-curable polyurethane resin) is more preferred as the constituting resin of the surface layer 5. Note that the constituting resin of the surface layer 5 and the constituting resin of the intermediate layer 4 can be the same or different. However, from the viewpoint of production efficiency, it is preferred that the constituting resin of the surface layer 5 and the constituting resin of the intermediate layer 4 are the same.

[0059] The particulate matter B dispersed in the surface layer 5 can be a single particle (non-aggregate), an aggregate formed by particles, or both.

[0060] There are no specific limitations on the constituent particles of granular body B dispersed in surface layer 5, and they can be any of those particles previously described as constituting particles of aggregate A dispersed in intermediate layer 4. One of these types of particles can be used alone, or two or more of these types of particles can be used in combination. Among these types of particles, fluoropolymer is preferred as a constituent particle of granular body B from the viewpoint of aggregateability and availability. Note that the constituent particles of granular body B and aggregate A can be the same or different. However, from the viewpoint of production efficiency, it is preferred that the constituent particles of granular body B and aggregate A are the same.

[0061] The average diameter d of the particles B dispersed in surface layer 5 B It needs to be no less than 1 μm and no more than 10 μm. Note the average diameter d of particle B. B This refers to the average primary particle size when granular body B is a non-aggregate, and the average secondary particle size or aggregate diameter when granular body B is an aggregate. The average diameter d of granular body B... B If the particle size is less than 1 μm, the particles are too small to achieve the desired effect through mixing. Furthermore, the average diameter d of particle B... B For particles larger than 10 μm, atomization may not be suppressed. Furthermore, from the viewpoint of more reliably achieving the desired effect, the average diameter d of particle B... B Preferably 3μm or larger, and from the viewpoint of more effectively suppressing atomization, preferably 8μm or smaller.

[0062] Note the average diameter d of granular body B. B Measurements can be made using the procedures described in the Examples section.

[0063] The average diameter d of granular body B B Preferably, the diameter d of the aggregate A dispersed in the intermediate layer 4 is smaller than the average diameter d. A In other words, the average diameter d of granular body B. B Relative to the average diameter d of aggregate A A The ratio (average diameter d) B / Average diameter d A The ratio is preferably less than 1.0. Regarding this, when the constituent particles of granular body B and aggregate A are of the same type, granular body B can be easily obtained by micronizing aggregate A using a dispersant or the like. Furthermore, the aforementioned ratio (average diameter d) B / Average diameter d A More preferably, it is 0.7 or less, and even more preferably, it is 0.4 or less.

[0064] The average diameter d of the particles B dispersed in surface layer 5 B Preferably, the thickness (resin thickness) is greater than that of the surface layer 5. In other words, when coating the resin composition comprising resin and granules B to form the surface layer 5, it is preferable to coat the resin composition to a thickness that causes the granules B to partially protrude. This makes the unevenness at the outer peripheral surface of the developing roller 1 more pronounced and can more effectively suppress toner leakage. Note that, in practice, the thickness (resin thickness) of the surface layer 5 can be set to, for example, not less than 1 μm and not more than 5 μm. Furthermore, the thickness (resin thickness) of the surface layer 5 can be less than the thickness (resin thickness) of the intermediate layer 4.

[0065] The particle content in surface layer 5 is preferably not less than 15 parts by weight and not more than 35 parts by weight relative to 100 parts by weight of resin. When the content is 15 parts by weight or more, the density of particulate B is sufficiently high, and effects such as improved toner supply are achieved. Furthermore, when the content is 35 parts by weight or less, coating unevenness during the production of surface layer 5 can be suppressed, and the effect of suppressing fogging can be further enhanced. From a similar point of view, the particle content in surface layer 5 is more preferably 20 parts by weight or more relative to 100 parts by weight of resin, and more preferably 30 parts by weight or less relative to 100 parts by weight of resin.

[0066] In addition to resin and granules B, surface layer 5 may contain other components such as conductive agents.

[0067] <Elastic Layer>

[0068] The developing roller 1 in this embodiment preferably further includes an elastic layer 3 between the shaft member 2 and the intermediate layer 4, such as Figure 1 As shown. This allows the developing roller 1 to be elastic and reduce the stress acting on the surface layer 5 when the surface layer 5 of the developing roller 1 is pressed against the photosensitive drum or developing blade, and also maintains the durability of the surface layer 5 well.

[0069] The elastic layer 3 is preferably formed of an elastomer, and more preferably of a foamed elastomer. The elastomer can be, for example, polyurethane, silicone rubber, ethylene propylene diene monomer (EPDM), nitrile rubber (NBR), natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), polynorbornene rubber, butyl rubber (IIR), chloroprene rubber (CR), acrylic rubber, epichlorohydrin rubber (ECO), ethylene-vinyl acetate copolymer (EVA), etc. One of these elastomers can be used alone, or two or more of these elastomers can be used in combination. In particular, polyurethane is preferably used in the elastic layer 3 among these elastomers.

[0070] The foamed elastomer can be produced by chemically foaming the elastomer using a foaming agent or by mechanically binding air to induce foaming (e.g., in polyurethane foams). When the elastic layer 3 is formed from a foamed elastomer, the foam preferably has a foaming ratio in the range of 1.5 to 50 times, and preferably has a foaming ratio of 0.05 g / cm³. 3 Up to 0.9 g / cm 3 The density within the range.

[0071] Furthermore, the cells in the aforementioned foam are preferably closed cells. In this case, the compression set properties of the elastic layer 3 can be improved. The method for forming closed cells in the foam can be suitably a method of foaming the elastomer raw material by mechanical stirring to obtain the foam.

[0072] The elastic layer 3 preferably contains a conductive agent. This allows for adjustment of the conductivity of the elastic layer 3. The conductive agent can be an electronic conductive agent, an ionic conductive agent, etc. A single conductive agent can be used, or two or more conductive agents can be used in combination. Furthermore, electronic and ionic conductive agents can be used in combination as conductive agents.

[0073] Examples of electronically conductive agents include: conductive carbon, such as Ketjen black and acetylene black; carbon black used in rubbers such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT; carbon black used for coloring after oxidation treatment, etc.; pyrolytic carbon black; natural graphite; artificial graphite; metal oxides, such as antimony-doped tin oxide, ITO, tin oxide, titanium oxide and zinc oxide; metals, such as nickel, copper, silver and germanium; conductive polymers, such as polyaniline, polypyrrole and polyacetylene; and conductive whiskers, such as carbon whiskers, graphite whiskers, titanium carbide whiskers, conductive potassium titanate whiskers, conductive barium titanate whiskers, conductive titanium oxide whiskers and conductive zinc oxide whiskers.

[0074] Examples of ionic conductive agents include ammonium salts such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonium, as well as perchlorates, chlorates, hydrochlorides, bromates, iodates, hydrofluoroborates, sulfates, ethyl sulfates, carbonates, sulfonates, etc., of alkali metals and alkaline earth metals (e.g., lithium, sodium, potassium, calcium, magnesium, etc.).

[0075] <Other Layers>

[0076] The developing roller 1 of this embodiment may also include layers other than the intermediate layer 4, surface layer 5 and elastic layer 3 described above.

[0077] For example, the developing roller 1 of this embodiment may further include an outer intermediate layer (not shown) radially outside the intermediate layer 4 and more specifically between the intermediate layer 4 and the surface layer 5. The outer intermediate layer may be a single layer or may be two or more layers. The outer intermediate layer can serve as an adhesive layer, and including the outer intermediate layer can increase the adhesion between the intermediate layer 4 and the surface layer 5 and increase the durability of the developing roller 1.

[0078] There are no specific restrictions on the resin constituting the outer intermediate layer, and any of those resins previously described as constituting intermediate layer 4 can be used. One of these resins can be used alone, or two or more of these resins can be used in combination. For example, the thickness of the outer intermediate layer (each layer) can be set to be not less than 1 μm and not more than 5 μm.

[0079] The developing roller 1 of this embodiment may further include an inner intermediate layer (not shown) radially inside the intermediate layer 4 and more specifically between the intermediate layer 4 and the shaft member 2 or the elastic layer 3. The inner intermediate layer may be a single layer or may be two or more layers. The inner intermediate layer can serve as an adhesive layer, and including the inner intermediate layer can increase the adhesion between the intermediate layer 4 and the shaft member 2 or the elastic layer 3, and can also increase the durability of the developing roller 1.

[0080] There are no specific limitations on the resin constituting the inner intermediate layer, and any of those resins previously described as constituting intermediate layer 4 can be used. One of these resins can be used alone, or two or more of these resins can be used in combination. For example, the thickness of the inner intermediate layer (each layer) can be set to be not less than 1 μm and not more than 5 μm.

[0081] <Manufacturing Method of Developing Roller>

[0082] The developing roller of this embodiment can be manufactured according to standard methods, without any specific limitations on the manufacturing method. For example, the coating liquid can be applied to the surface by preparing a resin composition (coating liquid) containing resin, particles and / or aggregates and other suitable components, and then optionally curing the coating liquid by irradiating it with ultraviolet light or an electron beam to form the layers, such as the intermediate layer 4 and the surface layer 5.

[0083] The method of applying the resin composition (coating liquid) can be dip coating, roller coating, spray coating, etc., without any specific limitations, and appropriate methods can be selected from these methods as needed.

[0084] <Applications of developing rollers>

[0085] The developing roller according to this disclosure can be used in various types of electrophotographic image forming apparatuses, such as copiers, fax machines, and laser beam printers (LBP). The image forming apparatus typically includes a photosensitive drum carrying an electrostatic latent image, a charging member located near and charging the photosensitive drum, a toner supply roller for supplying toner, a transfer member located near the photosensitive drum, and a cleaning member located near the photosensitive drum, and also includes a developing roller between the toner supply roller and the photosensitive drum. Furthermore, a developing blade (also referred to as a "layering blade") is typically disposed near the developing roller.

[0086] In an image forming apparatus, a voltage is applied between a photosensitive drum and a charging member to charge the photosensitive drum to a certain potential, and then an electrostatic latent image is formed on the photosensitive drum using an exposure tool. Next, toner is supplied from a toner supply roller to the photosensitive drum via a developing roller. During this supply, a developing blade flattens the toner on the developing roller into a more uniform thin layer, and the developing roller and photosensitive drum rotate in contact, causing the toner to adhere from the developing roller to the electrostatic latent image on the photosensitive drum, thus making the latent image visible. The toner attached to the latent image is transferred to a recording medium such as paper by a transfer member, and the toner remaining on the photosensitive drum after transfer is removed by a cleaning member.

[0087] As a result of using the developing roller according to this disclosure in an image forming apparatus, toner leakage and fogging can be suppressed. Furthermore, image density stability can be maintained even during continuous or long-term operation of the image forming apparatus.

[0088] Example

[0089] The following description of the present disclosure, and even more detailed descriptions thereof, is provided by way of examples. However, the present disclosure is not limited in any way to these examples and may be suitably changed without departing from the spirit of the present disclosure.

[0090] (Example 1)

[0091] A developing roller is produced by sequentially forming an elastic layer, an intermediate layer, an outer intermediate layer (adhesive layer), and a surface layer on a shaft member formed from an aluminum tube. Note that the intermediate layer is formed by roll coating a resin composition onto the elastic layer, which is obtained by mixing aggregates of polytetrafluoroethylene particles into a polyurethane resin (the main conditions for the intermediate layer are shown in Table 1). The adhesive layer is formed by roll coating a resin composition (coating liquid, a purchased product) onto the intermediate layer. The surface layer is formed by spraying a resin composition (dispersion liquid) onto the adhesive layer, which is obtained by mixing aggregates of polytetrafluoroethylene particles into a solvent containing polyurethane resin (the main conditions for the surface layer are shown in Table 1).

[0092] Note that in Example 1, the same particles were used as constituent particles of the aggregates in the intermediate layer and the aggregates in the surface layer, and the aggregates in the surface layer underwent further micronization using a dispersant equivalent to that in the intermediate layer.

[0093] The average diameter d of aggregate A (or particles) dispersed in the intermediate layer is measured using the following procedure. A .

[0094] Specifically, after the intermediate layer is formed, a laser microscope (Keyence VK-X3000) is used to acquire a surface image of the longitudinal central portion of the intermediate layer. Next, 100 aggregates A (or particles) are counted in this surface image, and the outer diameter data of these 100 aggregates A are acquired. The outer diameter data is used to calculate D50 as the average diameter d. A .

[0095] The average diameter d of particles B dispersed in the surface layer is measured using the following procedure. B .

[0096] Specifically, after the surface layer is formed, a laser microscope (Keyence VK-X3000) is used to acquire a surface image of the longitudinal central portion of the surface layer. Next, 100 particles B are counted in this surface image, and the outer diameter data of these 100 particles B are acquired. The outer diameter data is used to calculate D50 as the average diameter d. B .

[0097] The deformation strength (σ) of the particles is measured using the following procedure. 10% ).

[0098] Specifically, the deformation strength (σ) is determined using a particulate compressive strength tester (NS-A100 manufactured by Nano Seeds) via the following formula. 10% ).

[0099] σ 10% = F 10% / A

[0100] σ 10% : Deformation strength (Pa) at 10% compressive displacement of particle size.

[0101] F 10% Test force (N) at 10% compressive displacement of particle size.

[0102] A: Represents the area (the area of ​​the equivalent circle determined by the particle size measured before compression) (m²) 2 )

[0103] (Other embodiments and comparative examples)

[0104] Except for changing the conditions of the intermediate layer and / or surface layer as shown in Table 1, the developing roller is produced in the same manner as in Example 1.

[0105] The developing rollers of the various embodiments or comparative examples produced as described above were evaluated as follows. The results are shown in Table 1.

[0106] (1) Initial image density

[0107] The developed developing roller was installed in a Brother HL-L6400DW monochrome laser printer, and a solid black image was printed. The image density at five locations on the paper was measured using an X-Rite eXact Basic spectrometer. The average density at the five locations (average density) and the difference between the maximum and minimum values ​​(density difference) were calculated and evaluated using the following criteria.

[0108] A (Excellent): Average concentration of 1.2 or greater, concentration difference of 0.2 or less.

[0109] B (Good): Average concentration of 1.2 or greater, concentration difference less than 0.2.

[0110] C (Difference): Average concentration less than 1.2

[0111] (2) Image density after durable printing (stability of image density)

[0112] After measuring the initial image density as described above, durability printing (approximately 20,000 solid black images) was performed. The final image density at five locations on the paper was measured using an X-Rite spectrophotometer, the "eXact Basic". The average density at the five locations (average density) and the difference between the maximum and minimum values ​​(density difference) were calculated and evaluated using the following criteria.

[0113] A (Excellent): Average concentration of 1.2 or greater, concentration difference of 0.2 or less.

[0114] B (Good): Average concentration of 1.2 or greater, concentration difference less than 0.2.

[0115] C (Difference): Average concentration less than 1.2

[0116] (3) Atomization

[0117] The developed developing roller was installed in a Brother monochrome laser printer, the “HL-L6400DW,” and subjected to durability testing in an LL environment (10°C, 15%RH). The images obtained after the test were evaluated according to the following criteria.

[0118] A (Excellent): Toner fixing was not observed in areas of the image where it should not have been present.

[0119] B (Good): Slight fixing of toner was observed in areas of the image where toner should not be present.

[0120] C (Poor): Extensive fixing of the toner is observed where it should not be present.

[0121] (4) Toner leakage

[0122] The developed developing roller was installed in a Brother monochrome laser printer, the "HL-L6400DW," and durability tests were conducted in both LL (10°C, 15%RH) and HH (30°C, 80%RH) environments. Subsequently, the condition of the toner surrounding the developing roller was evaluated according to the following criteria.

[0123] A (Excellent): No toner was observed spraying from the end of the developing roller or dirt was observed in the seal.

[0124] B (Good): No toner was observed being ejected from the end of the developing roller, but dirt was observed in the seal.

[0125] C (Poor): Toner was observed spraying from the end of the developing roller, and dirt was observed in the seal.

[0126] [Table 1]

[0127]

[0128] As can be seen from Table 1, the developing roller according to the embodiments of the present disclosure can suppress toner leakage and fogging, and is also excellent in terms of image density stability.

[0129] Industrial availability

[0130] The developing roller according to this disclosure can be used in various electrophotographic image forming apparatuses, such as copiers, fax machines and laser beam printers (LBP).

[0131] Explanation of reference numerals in the attached figures

[0132] 1: Developing roller

[0133] 2: Shaft components

[0134] 3: Elastic layer

[0135] 4: Intermediate layer

[0136] 5: Surface layer

Claims

1. A developing roller, comprising: Shaft components; An intermediate layer is arranged radially outside the shaft member; as well as The surface layer, which is located at the outermost position, contains The intermediate layer comprises aggregates A formed of particles dispersed in the resin, and The surface layer comprises granular particles B dispersed in the resin, wherein the granular particles B are selected from at least one type selected from particles and aggregates formed from particles, and wherein the granular particles B have an average diameter d of not less than 1 μm and not greater than 10 μm. B .

2. The developing roller according to claim 1, wherein the aggregate A in the intermediate layer has an average diameter d of not less than 10 μm and not more than 35 μm. A .

3. The developing roller according to claim 1 or 2, wherein the content of the particles in the intermediate layer is not less than 10 parts by weight and not more than 30 parts by weight relative to 100 parts by weight of the resin.

4. The developing roller according to claim 1 or 2, wherein the content of the particles in the surface layer is not less than 15 parts by weight and not more than 35 parts by weight relative to 100 parts by weight of the resin.

5. The developing roller according to claim 1 or 2, wherein the average diameter d of the aggregate A is... A It is greater than the thickness of the intermediate layer.

6. The developing roller according to claim 1 or 2, wherein the average diameter d of the granules B is... B It is greater than the thickness of the surface layer.

7. The developing roller according to claim 1 or 2, further comprising an elastic layer between the shaft member and the intermediate layer.

8. The developing roller according to claim 1 or 2, further comprising an outer intermediate layer between the intermediate layer and the surface layer.

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