Conductive member for electrophotographic devices

Abstract

Provided is a conductive member for electrophotographic devices in which adhesion of toner and paper dust is minimized.　This conductive member 10 for electrophotographic devices comprises an elastic layer 14 and a surface layer 14 formed on the outer peripheral surface of the elastic layer 14. A plurality of protrusions 18 are formed on the outer peripheral surface of the surface layer 16, the tips of the protrusions 18 are configured as curved surfaces, the height h of the protrusions 18 is 1.0-10 nm inclusive, the width W of the protrusions 18 is 1.0-100 nm inclusive, and the width W of the protrusions 18 relative to the distance d between protrusions 18 is 0.5-1.5 inclusive.

Description

Conductive materials for electrophotographic equipment

[0001] The present invention relates to a conductive member for electrophotographic equipment, such as a charging roll or a developing roll, which is suitably used in electrophotographic equipment, such as copying machines, printers, and facsimiles, that employ an electrophotographic system.

[0002] Electrophotographic devices such as copiers, printers, and facsimiles that employ electrophotography typically incorporate a photosensitive drum, around which are arranged roll-shaped conductive members such as a charging roll, a developing roll, a transfer roll, and a toner supply roll, as well as dirt removal members such as a cleaning blade, and belt-shaped conductive members such as a transfer belt and a fixing belt. Copying and printing using this type of electrophotographic device is performed by forming an original image as an electrostatic latent image on the photosensitive drum, adhering toner to the electrostatic latent image to form a toner image, and transferring the toner image to copy paper.

[0003] Adherence of toner, toner additives, paper dust, and other contaminants to the surface of conductive materials can cause image defects. For example, when a charging roll is contaminated by toner or paper dust on the photosensitive drum, its charging performance deteriorates, preventing uniform charging of the photosensitive drum and resulting in image defects. In recent years, as equipment power consumption has decreased and cleaning blades are no longer installed, the demand for contamination resistance has increased even further.

[0004] Countermeasures against such stains include adding a modifier to the surface material to increase the water and oil repellency of the surface, or adding roughness-creating particles to the surface material to create surface irregularities.

[0005] Furthermore, Patent Document 1 proposes a charging roller having a nanostructure layer as a surface layer with a plurality of columnar protrusions on the surface in order to suppress adhesion of foreign matter such as toner, toner additives, and abrasion powder from the photosensitive drum.

[0006] Furthermore, Patent Document 2 proposes a charging roller having a nanopattern layer with a plurality of parallel groove-like irregularities as a surface layer in order to suppress adhesion of aggregates (foreign matter) that occur during use. These groove-like irregularities are formed by etching a microphase-separated structure of a lamellar structure, utilizing differences in carbon density of the monomer units.

[0007] JP 2013-076862 A JP 2013-076861 A

[0008] Contamination such as toner, toner additives, and paper dust on the surface of a conductive member can occur in a variety of ways, including superficial contamination, where the contamination simply adheres to the surface of the conductive member, as well as physical contamination, where the contamination is embedded or embedded in the surface of the conductive member. While adding a modifier to a surface layer material can remove superficial contamination, it is difficult to fully remove physical contamination that is embedded in the surface. Furthermore, adding roughness-forming particles to a surface layer material makes it difficult to form uniform surface irregularities due to particle aggregation. Furthermore, because the roughness-forming particles are too large compared to the contamination, the contamination tends to accumulate between the protrusions.

[0009] The surface layer of the charging roller in Patent Document 1 is a nanostructure layer having a plurality of protrusions with a columnar structure, and the surface that comes into contact with toner and other contaminants is the flat surface at the tips of the protrusions of the columnar structure. As a result, the surface layer of the charging roller in Patent Document 1 has a large contact area with contaminants, making it easy for contaminants to adhere to it.

[0010] The surface layer of the charging roller in Patent Document 2 is a nanopattern layer with multiple groove-like irregularities formed by etching a microphase separation structure of a lamellar structure, resulting in an irregular shape of a lamellar structure. The surface of the charging roller in Patent Document 2 is formed with irregularities made of protrusions and recesses, and the surface that comes into contact with toner and other contaminants is the protrusion, so the contact area with the contaminants is large and contaminants are more likely to adhere. In particular, the adhesion of contaminants such as small-sized toner external additives and paper dust is more pronounced than with large-sized toner.

[0011] The problem to be solved by the present invention is to provide a conductive member for electrophotographic equipment that is capable of suppressing adhesion of toner and paper dust.

[0012] The conductive member for electrophotographic equipment according to the present invention comprises an elastic layer and a surface layer formed on the outer peripheral surface of the elastic layer, wherein a plurality of convex portions are formed on the outer peripheral surface of the surface layer, the tips of the convex portions being configured with curved surfaces, the height of the convex portions being 1.0 nm or more and 10 nm or less, the width of the convex portions being 1.0 nm or more and 100 nm or less, and the ratio of the width of the convex portions to the spacing between the convex portions being 0.5 or more and 1.5 or less.

[0013] The convex portions may be hemispherical. The surface roughness Ra of the surface layer may be 0.5 nm or more and 10 nm or less. The spacing between the convex portions may be 1.0 nm or more and 100 nm or less. The surface layer may be composed of a styrene-butadiene block copolymer. The styrene content of the styrene-butadiene block copolymer may be 71 mass % or more and 85 mass % or less, and the styrene block copolymer content of the styrene-butadiene block copolymer may be 40 mol % or more and 75 mol % or less. The surface layer may contain carbon black. The surface layer may be composed of a self-assembled film of a diblock copolymer. The diblock copolymer may have a structure in which a phase consisting of one block polymer component and a phase consisting of the other block polymer component are arranged side by side in the thickness direction. The diblock copolymer may be a styrene-butadiene block copolymer, and a phase consisting of a styrene block polymer component may be arranged on a phase consisting of a butadiene block polymer component. The convex portions may be composed of a phase consisting of a styrene block polymer component of the diblock copolymer.

[0014] (1) The conductive member for electrophotographic equipment according to the present invention comprises an elastic layer and a surface layer formed on the outer peripheral surface of the elastic layer, wherein a plurality of protrusions are formed on the outer peripheral surface of the surface layer, the tips of the protrusions being configured with curved surfaces, the height of the protrusions being 1.0 nm or more and 10 nm or less, the width of the protrusions being 1.0 nm or more and 100 nm or less, and the ratio of the width of the protrusions to the spacing between the protrusions being 0.5 or more and 1.5 or less.

[0015] (2) In the above (1), the convex portion may be hemispherical.

[0016] (3) In the above (1) or (2), the surface roughness Ra of the surface layer is preferably 0.5 nm or more and 10 nm or less.

[0017] (4) In any one of (1) to (3) above, the interval between the convex portions may be 1.0 nm or more and 100 nm or less.

[0018] (5) In any one of the above (1) to (4), the surface layer may be made of a styrene-butadiene block copolymer.

[0019] (6) In the above (5), the styrene content of the styrene-butadiene block copolymer may be 71% by mass or more and 85% by mass or less, and the styrene block copolymer content of the styrene-butadiene block copolymer may be 40 mol% or more and 75 mol% or less.

[0020] (7) In any one of the above (1) to (6), the surface layer may contain carbon black.

[0021] (8) In any one of the above (1) to (7), the surface layer may be composed of a self-assembled film of a diblock copolymer.

[0022] (9) In the above (8), the diblock copolymer may have a structure in which a phase consisting of one block polymer component and a phase consisting of the other block polymer component are arranged side by side in the thickness direction.

[0023] (10) In the above (9), the diblock copolymer is preferably a styrene-butadiene block copolymer, and a phase consisting of a styrene block polymer component is disposed on a phase consisting of a butadiene block polymer component.

[0024] (11) In the above (10), the convex portions may be composed of a phase made of a styrene block polymer component of the diblock copolymer.

[0025] According to the conductive member for electrophotographic equipment of the present invention, a plurality of convex portions are formed on the outer peripheral surface of the surface layer, the tips of the convex portions are curved, the height of the convex portions is 1.0 nm or more and 10 nm or less, the width of the convex portions is 1.0 nm or more and 100 nm or less, and the ratio of the width of the convex portions to the spacing between the convex portions is 0.5 or more and 1.5 or less, thereby suppressing the adhesion of toner and paper powder.

[0026] When the convex portions are hemispherical, the tips of the convex portions are curved, which reduces the contact area with stains such as toner and paper dust, and is excellent in preventing the adhesion of stains such as toner and paper dust.

[0027] When the surface roughness Ra of the surface layer is 0.5 nm or more and 10 nm or less, the surface roughness is appropriate for preventing adhesion of stains such as toner and paper dust, and is therefore excellent in preventing adhesion of stains such as toner and paper dust.

[0028] When the interval between the protrusions is 1.0 nm or more and 100 nm or less, the plurality of protrusions are uniformly arranged on the outer peripheral surface of the surface layer, which is effective in suppressing the adhesion of contaminants such as toner and paper powder.

[0029] Furthermore, when the surface layer is made of a styrene-butadiene block copolymer, the self-organization of the block copolymer allows multiple fine and uniform convex portions to be formed on the outer circumferential surface of the surface layer, which is highly effective in suppressing the adhesion of contaminants such as toner and paper dust.

[0030] Furthermore, when the styrene content of the styrene-butadiene block copolymer is 71% by mass or more and 85% by mass or less, and the styrene block copolymer content of the styrene-butadiene block copolymer is 40 mol% or more and 75 mol% or less, convex portions of appropriate size are easily formed. Furthermore, a lamellar structure (a fine pattern such as wrinkles) is less likely to be formed. This results in an excellent effect of removing relatively large contaminants such as toner. Furthermore, the contact area with relatively small contaminants such as paper dust and toner external additives is reduced, resulting in an excellent effect of suppressing the adhesion of small contaminants and removing them.

[0031] When the surface layer contains carbon black, it can exhibit excellent electrical conductivity.

[0032] Furthermore, when the surface layer is made of a self-assembled film of a diblock copolymer, a plurality of fine and uniform convex portions can be formed on the outer peripheral surface of the surface layer, which is highly effective in suppressing the adhesion of contaminants such as toner and paper dust.

[0033] When the diblock copolymer has a structure in which a phase consisting of one block polymer component and a phase consisting of the other block polymer component are arranged side by side in the thickness direction, the self-organization of the block copolymer allows the formation of a plurality of fine and uniform convex portions on the outer peripheral surface of the surface layer, which is highly effective in suppressing the adhesion of contaminants such as toner and paper dust.

[0034] When the diblock copolymer is a styrene-butadiene block copolymer and a phase consisting of a styrene block polymer component is disposed on a phase consisting of a butadiene block polymer component, the block copolymer self-organizes to form a plurality of fine and uniform convex portions on the outer peripheral surface of the surface layer, which is highly effective in suppressing the adhesion of contaminants such as toner and paper dust.

[0035] When the convex portions are composed of a phase consisting of a styrene block polymer component of the diblock copolymer, the self-organization of the block copolymer allows a plurality of fine and uniform convex portions to be formed on the outer peripheral surface of the surface layer, which is highly effective in suppressing the adhesion of contaminants such as toner and paper powder.

[0036] 1A is a schematic external view of a conductive roll for electrophotographic equipment according to one embodiment of the present invention, and its radial cross-sectional view (b). FIG. 1B is an enlarged schematic view of a cross-section of a surface layer. FIG. 1C is a schematic view illustrating self-organization of a surface layer material. FIG. 1A is a schematic external view of a conductive belt for electrophotographic equipment according to one embodiment of the present invention, and its radial cross-sectional view (b). FIG. 1C is an enlarged photograph (1 μm×1 μm) of the surface layer of an example and a comparative example.

[0037] The conductive member for electrophotographic devices (hereinafter, sometimes simply referred to as the conductive member) according to the present invention will be described in detail. The conductive member includes an elastic layer and a surface layer formed on the outer peripheral surface of the elastic layer. The conductive member is suitable for conductive rolls such as charging rolls, developing rolls, transfer rolls, and toner supply rolls used in electrophotographic devices such as copiers, printers, and facsimiles that employ electrophotography, as well as endless belts (conductive belts) such as intermediate transfer belts, paper transfer transport belts, and fixing belts.

[0038] Fig. 1 shows a conductive roll according to one embodiment of the present invention. Fig. 2 shows an enlarged schematic view of a cross section of the surface layer of the conductive roll. Fig. 3 shows a schematic view illustrating self-organization of the surface layer material. Fig. 4 shows a conductive belt according to one embodiment of the present invention.

[0039] The conductive roll 10 includes a shaft 12, an elastic layer 14 formed on the outer peripheral surface of the shaft 12, and a surface layer 16 formed on the outer peripheral surface of the elastic layer 14. The elastic layer 14 is a layer (base layer) that serves as the base of the conductive roll 10. The surface layer 16 is a layer that appears on the surface of the conductive roll 10.

[0040] The shaft 12 is not particularly limited as long as it is conductive. Specific examples include a solid or hollow core made of metal such as iron, stainless steel, or aluminum. An adhesive, primer, or the like may be applied to the surface of the shaft 12 as needed. The adhesive, primer, or the like may be made conductive as needed.

[0041] The elastic layer 14 contains a crosslinked rubber. The elastic layer 14 is formed from a conductive rubber composition containing an uncrosslinked rubber. The crosslinked rubber is obtained by crosslinking the uncrosslinked rubber. The uncrosslinked rubber may be a polar rubber or a non-polar rubber.

[0042] Polar rubber is a rubber having a polar group, and examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Specific examples of polar rubber include hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (a copolymer of acrylic acid ester and 2-chloroethyl vinyl ether, ACM), chloroprene rubber (CR), and epoxidized natural rubber (ENR). Among the polar rubbers, hydrin rubber and nitrile rubber (NBR) are more preferred from the viewpoint that the volume resistivity tends to be particularly low.

[0043] Examples of the hydrin rubber include an epichlorohydrin homopolymer (CO), an epichlorohydrin-ethylene oxide binary copolymer (ECO), an epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), and an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (GECO).

[0044] Examples of urethane rubber include polyether-type urethane rubber having an ether bond in the molecule. Polyether-type urethane rubber can be produced by reacting a polyether having hydroxyl groups at both ends with a diisocyanate. Examples of polyethers include, but are not limited to, polyethylene glycol and polypropylene glycol. Examples of diisocyanates include, but are not limited to, tolylene diisocyanate and diphenylmethane diisocyanate.

[0045] Examples of non-polar rubbers include silicone rubber (Q), isoprene rubber (IR), natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), etc. Among non-polar rubbers, silicone rubber is more preferable from the viewpoint of low hardness and resistance to settling (excellent elastic recovery).

[0046] The elastic layer 14 preferably contains one or more of isoprene rubber, nitrile rubber, and hydrin rubber. When the elastic layer 14 contains one or more of isoprene rubber, nitrile rubber, and hydrin rubber, the compression set is small, and the occurrence of streak images corresponding to deformed portions when the conductive member 10 is set is suppressed.

[0047] Examples of the crosslinking agent include a sulfur crosslinking agent, a peroxide crosslinking agent, and a dechlorination crosslinking agent. These crosslinking agents may be used alone or in combination of two or more.

[0048] Examples of the sulfur crosslinking agent include conventionally known sulfur crosslinking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram vulcanization accelerators, and polymeric polysulfides.

[0049] Examples of the peroxide crosslinking agent include conventionally known peroxide crosslinking agents such as peroxyketals, dialkyl peroxides, peroxyesters, ketone peroxides, peroxydicarbonates, diacyl peroxides, and hydroperoxides.

[0050] Examples of the dechlorinating crosslinking agent include dithiocarbonate compounds, more specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, and 5,8-dimethylquinoxaline-2,3-dithiocarbonate.

[0051] The amount of the crosslinking agent to be added is preferably within a range of 0.1 to 2 parts by mass, more preferably within a range of 0.3 to 1.8 parts by mass, and even more preferably within a range of 0.5 to 1.5 parts by mass, per 100 parts by mass of the uncrosslinked rubber, from the viewpoint of preventing bleeding.

[0052] When a dechlorination crosslinking agent is used as the crosslinking agent, a dechlorination crosslinking accelerator may be used in combination. Examples of the dechlorination crosslinking accelerator include 1,8-diazabicyclo(5,4,0)undecene-7 (hereinafter abbreviated as DBU) or a weak acid salt thereof. The dechlorination crosslinking accelerator may be used in the form of DBU, but from the viewpoint of handling, it is preferable to use it in the form of a weak acid salt. Examples of weak acid salts of DBU include carbonate, stearate, 2-ethylhexyl salt, benzoate, salicylate, 3-hydroxy-2-naphthoate, phenol resin salt, 2-mercaptobenzothiazole salt, and 2-mercaptobenzimidazole salt.

[0053] The content of the dechlorination crosslinking accelerator is preferably within a range of 0.1 to 2 parts by mass, more preferably 0.3 to 1.8 parts by mass, and even more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of the uncrosslinked rubber, from the viewpoint of preventing bleeding.

[0054] A conductive agent can be blended into the elastic layer 14 to impart conductivity. Examples of conductive agents include electronic conductive agents and ionic conductive agents. Examples of electronic conductive agents include carbon black, graphite, and conductive metal oxides. Examples of conductive metal oxides include conductive titanium oxide, conductive zinc oxide, and conductive tin oxide. Examples of ionic conductive agents include quaternary ammonium salts, borates, and surfactants. Various additives may also be added to the elastic layer 14 as needed. Examples of additives include lubricants, vulcanization accelerators, antioxidants, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, antifoaming agents, pigments, and mold release agents.

[0055] The elastic layer 14 can be adjusted to a predetermined volume resistivity by adjusting the type of crosslinked rubber, the amount of ionic conductive agent, the amount of electronic conductive agent, etc. ２ ~10 １０ Ω cm, 10 ３ ~10 ９ Ω cm, 10 ４ ~10 ８The range may be appropriately set to Ω·cm.

[0056] The thickness of the elastic layer 14 is not particularly limited, and may be set appropriately within the range of 0.1 to 10 mm depending on the application.

[0057] The surface layer 16 functions as a protective layer for the roll surface, etc. A plurality of protrusions 18 are formed on the outer peripheral surface of the surface layer 16. The protrusions 18 are hemispherical, and the tips of the protrusions 18 are curved. The height h of the protrusions 18, the width W of the protrusions 18, and the size of the width W of the protrusions 18 relative to the spacing d between the protrusions 18 are within a specific range. In this way, the surface layer 16 has a plurality of fine, uniform protrusions 18 on its outer peripheral surface, which allows toner, toner additives, paper dust, and other contaminants to slide off, thereby suppressing the adhesion of contaminants (toner and paper dust).

[0058] The height h of the protrusions 18 is 1.0 nm or more and 10 nm or less. If the height h of the protrusions 18 is less than 1.0 nm, the protrusions 18 are too small, resulting in a reduced effect of removing relatively large contaminants (approximately 5 μm) such as toner. On the other hand, if the height h of the protrusions 18 exceeds 10 nm, the protrusions 18 are too large, resulting in a large contact area with relatively small contaminants (approximately 100 nm) such as paper dust and toner additives, making the small contaminants more likely to adhere and reducing the effect of removing them. From the above viewpoints, the height h of the protrusions 18 is preferably 1.5 nm or more, more preferably 2.0 nm or more, and even more preferably 2.5 nm or more. Furthermore, the height h of the protrusions 18 is preferably 9.0 nm or less, more preferably 8.0 nm or less, and even more preferably 7.0 nm or less.

[0059] The width W of the protrusions 18 represents the diameter (outer diameter) of the hemispherical protrusions 18. The width W of the protrusions 18 is 1.0 nm or more and 100 nm or less. If the width W of the protrusions 18 is less than 1.0 nm, the protrusions 18 are too small, resulting in a reduced effect of removing relatively large contaminants such as toner. On the other hand, if the width W of the protrusions 18 is more than 100 nm, the protrusions 18 are too large, resulting in a large contact area with relatively small contaminants such as paper dust and toner additives. This makes the small contaminants more likely to adhere, reducing the effect of removing them. From the above viewpoints, the width W of the protrusions 18 is preferably 5.0 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and particularly preferably 40 nm or more. The width W of the protrusions 18 is preferably 90 nm or less, more preferably 80 nm or less, and even more preferably 70 nm or less.

[0060] The spacing d between the protrusions 18 is preferably 1.0 nm or more and 100 nm or less. If the spacing d between the protrusions 18 is less than 1.0 nm, the protrusions 18 tend to connect to form ridges, which increases the contact area with relatively small contaminants such as paper dust and toner additives, making the small contaminants more likely to adhere and reducing the effectiveness of removing them. On the other hand, if the spacing d between the protrusions 18 exceeds 100 nm, the spacing d between the protrusions 18 becomes too large, resulting in a small number of protrusions 18 and a reduced effectiveness in removing contaminants. From the above viewpoints, the spacing d between the protrusions 18 is preferably 5.0 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and particularly preferably 40 nm or more. Furthermore, the spacing d between the protrusions 18 is preferably 90 nm or less, more preferably 80 nm or less, and even more preferably 70 nm or less.

[0061] The ratio of the width W of the convex portions 18 to the spacing d between the convex portions 18 is preferably 0.5 or more and 1.5 or less. If the ratio of the width W of the convex portions 18 to the spacing d between the convex portions 18 is less than 0.5, the spacing d between the convex portions 18 is too large, the number of convex portions 18 is small, and the stain removal effect is reduced. On the other hand, if the ratio of the width W of the convex portions 18 to the spacing d between the convex portions 18 is more than 1.5, the convex portions 18 tend to be connected to form convex stripes, which increases the contact area with relatively small stains such as paper dust and toner additives, making small stains more likely to adhere and reducing the effect of removing them. From the above viewpoints, the ratio of the width W of the convex portions 18 to the spacing d between the convex portions 18 is preferably 0.6 or more, more preferably 0.7 or more, and even more preferably 0.8 or more. The ratio of the width W of the convex portions 18 to the spacing d between the convex portions 18 is preferably 1.4 or less, more preferably 1.3 or less, and even more preferably 1.2 or less.

[0062] The surface roughness Ra of the surface layer 16 is preferably 0.5 nm or more and 10 nm or less. If the surface roughness Ra is less than 0.5 nm, the surface roughness is too small, resulting in a reduced effect of removing relatively large contaminants such as toner. On the other hand, if the surface roughness Ra exceeds 10 nm, the surface roughness is too large, resulting in a large contact area with relatively small contaminants such as paper dust and toner additives, making the small contaminants more likely to adhere and reducing the effect of removing them. If the surface roughness Ra is 0.5 nm or more and 10 nm or less, the surface roughness is appropriate for contaminants such as toner and paper dust, thereby providing an excellent effect of suppressing the adhesion of contaminants such as toner and paper dust. From the above viewpoints, the surface roughness Ra is preferably 0.8 nm or more, more preferably 2.0 nm or more. The surface roughness Ra is preferably 5.0 nm or less, more preferably 4.0 nm or less, and even more preferably 3.0 nm or less.

[0063] The height h of the protrusions 18, the width W of the protrusions 18, the spacing d between the protrusions 18, and the surface roughness Ra can be determined by performing image analysis using height images from a scanning probe microscope (SPM). The spacing d between the protrusions 18 can be determined from the length between the highest points of adjacent protrusions 18. The surface roughness Ra is the arithmetic mean roughness. Each value is expressed as the average of values ​​calculated at three arbitrary points per location after SPM height images are obtained from two arbitrary locations on the surface layer 16.

[0064] The fine, uniform uneven structure of the surface layer 16 may be formed by various methods, for example, by the self-assembly of a diblock copolymer. This effectively forms an optimal number of convex portions 18, resulting in a fine, uniform uneven structure. The diblock copolymer is preferably a combination of a flexible polymer and a rigid polymer. Examples of flexible polymers include butadiene, isoprene, polyethylene oxide, and polyacrylic acid. Examples of rigid polymers include styrene and polymethyl methacrylate. Examples of diblock copolymers include styrene-butadiene block copolymers and styrene-isoprene diblock copolymers. Of these, styrene-butadiene block copolymers are particularly preferred.

[0065] The styrene content of the styrene-butadiene block copolymer is preferably 71% by mass or more and 85% by mass or less, and the styrene block copolymer content of the styrene-butadiene block copolymer is preferably 40 mol% or more and 75 mol% or less. When the styrene content is 71% by mass or more and the styrene block copolymer content is 40 mol% or more, it is easy to form convex portions 18 of an appropriate size that are not too small. This provides an excellent effect in removing relatively large contaminants such as toner. Furthermore, when the styrene content is 85% by mass or less and the styrene block copolymer content is 75 mol% or less, it is easy to form convex portions 18 of an appropriate size that are not too large. Furthermore, a lamellar structure (a fine pattern such as wrinkles) is unlikely to be formed. This reduces the contact area with relatively small contaminants such as paper dust and toner external additives, providing an excellent effect in suppressing the adhesion of small contaminants and removing them. From the above viewpoints, it is more preferable that the styrene content be 73% by mass or more and the styrene block copolymer content be 45 mol% or more, and even more preferable that the styrene content be 75% by mass or more and the styrene block copolymer content be 50 mol% or more. From the above viewpoints, the styrene content is more preferably 80% by mass or less and the styrene block copolymer content is 70% by mol or less, and further preferably 78% by mass or less and the styrene block copolymer content is 65% by mol or less. The styrene content can be calculated by NMR.

[0066] The molecular weight of the styrene-butadiene block copolymer is preferably Mw 80,000 or more and Mw 180,000 or less. When the molecular weight of the styrene-butadiene block copolymer is within the above range, it is easy to form convex portions 18 of optimal size. From this viewpoint, the molecular weight of the styrene-butadiene block copolymer is more preferably Mw 100,000 or more and Mw 160,000 or less, and even more preferably Mw 120,000 or more and Mw 160,000 or less. The molecular weight can be calculated by GPC.

[0067] As shown in Figure 3, the diblock copolymer of an appropriate composition undergoes self-assembly, resulting in a surface layer 16 in which a phase 17a made of one block polymer component and a phase 17b made of the other block polymer component are arranged side by side in the thickness direction. For example, in the case of a styrene-butadiene block copolymer, the phase 17a made of the butadiene block polymer component is arranged below in the thickness direction, and the phase 17b made of the styrene block polymer component is arranged above it. The protrusions 18 are formed by the phase 17b made of the styrene block polymer component of the diblock copolymer.

[0068] The surface layer 16 can be formed by applying a coating material containing a diblock copolymer onto the outer peripheral surface of the elastic layer 14 and drying the coating material, which is the surface layer material, to form a surface layer 16 having a uniform pattern of a plurality of minute protrusions 18 due to self-aggregation.

[0069] To impart conductivity to the surface layer 16, a conductive agent such as carbon black, graphite, conductive titanium oxide, conductive zinc oxide, conductive tin oxide, or an ionic conductive agent (quaternary ammonium salt, borate, surfactant, etc.) may be appropriately added. Various additives may also be appropriately added as needed. Furthermore, to ensure surface roughness, roughness-forming particles may or may not be added to the surface layer 16.

[0070] The surface layer 16 preferably contains carbon black. When the surface layer 16 contains carbon black, excellent conductivity can be exhibited. The content of carbon black in the surface layer 16 is preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the styrene-butadiene block copolymer.

[0071] The roughness-forming particles form surface irregularities on the surface layer 16. Examples of the roughness-forming particles include resin particles and silica particles. Examples of the resin particles include urethane particles, silicone particles, and acrylic particles. The average particle diameter of the roughness-forming particles is preferably within the range of 3 to 50 μm. The average particle diameter of the roughness-forming particles can be calculated from the median diameter using a laser diffraction particle size distribution analyzer.

[0072] The thickness of the surface layer 16 is not particularly limited, but is preferably in the range of 0.01 to 100 μm, more preferably in the range of 0.1 to 20 μm, and even more preferably in the range of 0.3 to 10 μm. ７ ~10 １２ Ω cm, more preferably 10 ８ ~10 １１ Ω cm, more preferably 10 ９ ~10 １０ It is in the range of Ω·cm.

[0073] The conductive roll 10 can be manufactured, for example, as follows. First, the shaft 12 is coaxially placed in the hollow portion of a roll-forming mold, a rubber composition is injected, heated and cured, and then the mold is removed, or the rubber composition is extruded onto the surface of the shaft 12, to form the elastic layer 14 on the outer periphery of the shaft 12. Next, a surface layer-forming composition is applied to the outer periphery of the formed elastic layer 14, and heat treatment is performed as necessary to form the surface layer 16. In this manner, the conductive roll 10 can be manufactured.

[0074] The surface layer-forming composition contains the above-mentioned main material, a conductive agent, and other additives as needed. Examples of other additives include a crosslinking agent for the polymer component, a leveling agent, and a surface modifier. To adjust the viscosity, the surface layer-forming composition may contain an appropriate solvent, such as an organic solvent such as methyl ethyl ketone (MEK), toluene, acetone, ethyl acetate, butyl acetate, methyl isobutyl ketone (MIBK), THF, or DMF, or a water-soluble solvent such as methanol or ethanol. Various coating methods, such as roll coating, dipping, and spray coating, can be used for the coating method.

[0075] According to the conductive roll 10 having the above-described configuration, a plurality of protrusions 18 are formed on the outer peripheral surface of the surface layer 16, the protrusions 18 are hemispherical, the tips of the protrusions 18 are formed with curved surfaces, and the height h of the protrusions 18, the width W of the protrusions 18, and the size of the width W of the protrusions 18 relative to the interval d between the protrusions 18 are within a specific range. In this way, the surface layer 16 has a plurality of fine, uniform protrusions 18 of the nano-order on its outer peripheral surface, which allows toner, toner additives, paper dust, and other contaminants to slide off, thereby suppressing the adhesion of contaminants (toner and paper dust).

[0076] 4 , the conductive belt (endless belt) 20 includes an elastic layer 24 and a surface layer 26 formed on the outer peripheral surface of the elastic layer 24. The elastic layer 24 is a base layer (substrate layer) of the conductive belt 20. The surface layer 26 is a layer that appears on the surface of the conductive belt 20.

[0077] The elastic layer 24 has the same configuration as the elastic layer 14 of the conductive roll 10. The surface layer 26 has the same configuration as the surface layer 16 of the conductive roll 10. The conductive belt 20 also exhibits the same effects as the conductive roll 10.

[0078] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0079] For example, in the above embodiment, the convex portion 18 is shown to be hemispherical, but the convex portion 18 is not limited to a hemispherical shape as long as the tip of the convex portion 18 has a curved surface. Also, the hemispherical shape may be a hemisphere of a true sphere or a hemisphere of an oval sphere.

[0080] Furthermore, for example, in the above embodiment, the surface layer 16 is in contact with the elastic layer 14 and is composed of a single layer. However, another layer may be present between the surface layer 16 and the elastic layer 14. Examples of such another layer include a resistance adjustment layer. The surface layer 16 may also be composed of two layers. In a two-layer surface layer, the lower layer may be composed of, for example, a layer containing roughness-imparting particles, and the upper layer may be composed of a layer having the above-described microstructure and not containing roughness-imparting particles. The polymer component of the lower layer may be the same as that of the upper layer, or may be a different polymer component, such as polyamide, acrylic resin, urethane resin, silicone resin, or fluoropolymer.

[0081] The present invention will be described in detail below using examples and comparative examples.

[0082] Example Preparation of Surface Layer Forming Composition 100 parts by mass of a styrene-butadiene block copolymer was added to 495 parts by mass of MEK together with 30 parts by mass of carbon black, and dissolved in a steam oven at 50°C for 3 hours to prepare a surface layer forming composition.

[0083] <Formation of Surface Layer> The surface layer-forming composition was applied to a PET sheet (30 cm x 30 cm) by bar coating to a thickness of 100 μm (application size: 20 cm x 10 cm). The sheet was then air-dried at room temperature for about 1 hour to remove the solvent, forming a film with a thickness of about 20 μm. This formed the surface layer.

[0084] Comparative Example 1-2 A surface layer was formed in the same manner as in the example.

[0085] The materials used in the surface layer forming composition are as follows. Styrene-butadiene block copolymer <1>: Asahi Kasei "Asaflex 825" (styrene content 78% by mass, styrene block copolymer content 50 mol%, molecular weight Mw 140,000) Styrene-butadiene block copolymer <2>: Asahi Kasei "Asaflex 840" (styrene content 76% by mass, styrene block copolymer content 56 mol%, molecular weight Mw 150,000) Styrene-butadiene block copolymer <3>: Asahi Kasei "Asaflex 805" (styrene content 77% by mass, styrene block copolymer content 76 mol%, molecular weight Mw 10,5000) Styrene-butadiene block copolymer <4>: Asahi Kasei "Asaflex 830" (styrene content 70% by mass, styrene block copolymer content 55 mol%, molecular weight Mw 135,000) Carbon black: Lion "Ketjen EC300"

[0086] The surface microstructure of each surface layer was analyzed. Furthermore, each surface layer was subjected to a toner adhesion test and a paper dust / external additive adhesion test. The measurement and evaluation methods were as follows. The results are shown in the table below.

[0087] (Analysis of Surface Microstructure) The height, width (diameter) and spacing of the convex portions, and surface roughness Ra were determined by image analysis using height images from a scanning probe microscope (SPM). The spacing between the convex portions was determined from the length between the highest points of adjacent convex portions. The surface roughness Ra is the arithmetic mean roughness. Each value was calculated by taking SPM height images from any two locations on the prepared film, then calculating each value at any three points per location, and expressing the average. Scanning probe microscope (SPM) photographs are shown in Figure 5. Figure 5(a) shows Example 1, Figure 5(b) shows Example 2, Figure 5(c) shows Comparative Example 1, and Figure 5(d) shows Comparative Example 2.

[0088] (Toner Adhesion Test) The entire surface of each surface layer prepared was dusted with toner (size: approximately 5 μm), and centrifuged at 12,000 rpm. After centrifugation, the surface of the surface layer was observed under a microscope, and the area of ​​the toner-adhered portion was detected using ImageJ, and this was taken as the toner adhesion rate. A toner adhesion rate of 25% or less was evaluated as "Good," and a toner adhesion rate of 26% or more was evaluated as "Poor."

[0089] (Paper Dust and Additive Adhesion Test) Calcium carbonate of 100 nm or less was used to simulate paper dust, and magnesium oxide of 100 nm or less was used to simulate toner external additives. The entire surface of each prepared surface layer was dusted with calcium carbonate and magnesium oxide, and the surface was covered with a PET sheet (130 μm thick). A physical load was applied by moving a roller with a 5 kg load back and forth 10 times over the PET sheet. The PET sheet was peeled off to obtain a sample, and air was blown from a distance of 10 cm. The surface after air blowing was observed using a laser microscope. The area of ​​the contaminated area was detected using ImageJ and recorded as the paper dust and additive adhesion rate. A paper dust and additive adhesion rate of 18% or less was evaluated as "Good," and a paper dust and additive adhesion rate of 19% or more was evaluated as "Poor."

[0090]

[0091] Comparative Example 1 uses a block copolymer as the surface layer material, but as shown in Figure 5(c), a lamellar structure is formed on the surface. This increases the contact area with relatively small contaminants such as paper dust and toner additives, making it less effective at removing small contaminants. Comparative Example 2 uses a block copolymer as the surface layer material, but as shown in Figure 5(d) and Table 1, the size of the protrusions is too small, making it less effective at removing relatively large contaminants such as toner.

[0092] In contrast, in the example, a block copolymer is used as the surface layer material, and as shown in Figures 5(a) and 5(b), multiple protrusions are formed on the surface of the surface layer, each of which is hemispherical with a curved tip. The height, width (diameter), and relative spacing of the protrusions are all within specific ranges. This provides excellent removal of both relatively large contaminants such as toner and relatively small contaminants such as paper dust and toner additives.

[0093] Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications are possible within the scope of the invention.

[0094] REFERENCE SIGNS LIST 10 Conductive roll 12 Shaft 14 Elastic layer 16 Surface layer 18 Convex portion 20 Conductive belt 24 Elastic layer 26 Surface layer h Convex height W Convex width d Convex spacing 17a Phase consisting of butadiene block polymer component 17b Phase consisting of styrene block polymer component

Claims

1. An elastic layer and a surface layer formed on an outer peripheral surface of the elastic layer, A plurality of protrusions are formed on the outer circumferential surface of the surface layer, The tip of the protrusion is formed of a curved surface, The height of the protrusions is 1.0 nm or more and 10 nm or less, The width of the protrusion is 1.0 nm or more and 100 nm or less, A conductive member for electrophotographic equipment, wherein a ratio of a width of the protrusions to a distance between the protrusions is 0.5 or more and 1.5 or less.

2. The conductive member for an electrophotographic device according to claim 1 , wherein the protrusions are semispherical.

3. 3. The conductive member for an electrophotographic device according to claim 1, wherein the surface roughness Ra of the surface layer is 0.5 nm or more and 10 nm or less.

4. 3. The conductive member for an electrophotographic device according to claim 1, wherein the interval between the protrusions is from 1.0 nm to 100 nm.

5. 3. The conductive member for electrophotographic equipment according to claim 1, wherein the surface layer is made of a styrene-butadiene block copolymer.

6. The conductive member for electrophotographic devices according to claim 5, wherein the styrene content of the styrene-butadiene block copolymer is 71% by mass or more and 85% by mass or less, and the styrene content of the styrene-butadiene block copolymer is 40 mol% or more and 75 mol% or less.

7. 3. The conductive member for an electrophotographic device according to claim 1, wherein the surface layer contains carbon black.

8. 3. The conductive member for electrophotographic equipment according to claim 1, wherein the surface layer is composed of a self-assembled film of a diblock copolymer.

9. 9. The conductive member for electrophotographic equipment according to claim 8, wherein the diblock copolymer has a structure in which a phase made of one block polymer component and a phase made of the other block polymer component are arranged side by side in the thickness direction.

10. 10. The conductive member for electrophotographic equipment according to claim 9, wherein the diblock copolymer is a styrene-butadiene block copolymer, and a phase made of a styrene block polymer component is disposed on a phase made of a butadiene block polymer component.

11. 11. The conductive member for an electrophotographic device according to claim 10, wherein the convex portion is constituted by a phase made of a styrene block polymer component of the diblock copolymer.

12. The convex portion is hemispherical, The surface roughness Ra of the surface layer is 0.5 nm or more and 10 nm or less, The interval between the protrusions is 1.0 nm or more and 100 nm or less, the surface layer is composed of a styrene-butadiene block copolymer, The styrene content of the styrene-butadiene block copolymer is 71% by mass or more and 85% by mass or less, and the styrene content of the styrene-butadiene block copolymer is 40 mol% or more and 75 mol% or less, 2. The conductive member for an electrophotographic device according to claim 1, wherein the surface layer contains carbon black.