Endless Belt, Transfer Device, and Image Forming Apparatus

Abstract

The present invention relates to an endless belt, a transfer device, and an image forming apparatus. The endless belt is a single-layer body comprising a layer of an imide resin and conductive particles, or a laminate having the layer as the outermost layer. When the common logarithm of the surface resistivity of the outer peripheral surface of the layer measured using a ring probe under the conditions of an applied voltage of 100 V, an applied time of 3 seconds, and a load of 1 kg is x (log Ω / □), and the common logarithm of the volume resistivity of the layer measured using a ring probe under the conditions of an applied voltage of 100 V, an applied time of 5 seconds, and a load of 1 kg is y (log Ω·cm), the value of y / x is 0.8992 or more and 1.0157 or less.

Description

Technical Field

[0001] The present invention relates to an endless belt, a transfer device, and an image forming device. Background Art

[0002] In image forming devices using electrophotography (copiers, fax machines, printers, etc.), a toner image formed on the surface of an image holder is transferred to the surface of a recording medium and fixed on the recording medium to form an image. It should be noted that a conductive endless belt, such as an intermediate transfer belt, is used to transfer the toner image to the recording medium.

[0003] For example, Japanese Patent Application Laid-Open No. 2007-011117 discloses “an intermediate transfer belt having at least a surface layer on a substrate, wherein the surface layer contains aggregates of conductive particles having an average particle size of 0.5 to 25 μm.”

[0004] Japanese Patent Application Laid-Open No. 2007-078789 discloses “an intermediate transfer belt having at least a surface layer on a substrate, wherein the surface layer contains metal-coated resin particles.” Summary of the Invention

[0005] Technical problem to be solved by the invention

[0006] In an image forming device that uses an endless belt as an intermediate transfer body, if a recording medium with a large surface convexity such as embossed paper (hereinafter also referred to as "embossed paper") is used, when the toner image is transferred from the intermediate transfer body to the recording medium, the intermediate transfer body cannot follow the convexity and concavity of the recording medium, the transferability is reduced, and white spots in the image may occur.

[0007] The technical problem to be solved by the present invention is to provide an endless belt, which has excellent transferability to embossed paper when used as an intermediate transfer body, compared with a case where the endless belt is a single-layer body comprising an imide resin and conductive particles, and a layer with a y / x value of less than 0.8992 or greater than 1.0157, or a laminate having the above-mentioned layer in the outermost layer.

[0008] Means for solving technical problems

[0009] The above technical problems are solved by the following solutions.

[0010] According to the first embodiment of the present invention, an endless belt is provided, which is a single-layer body comprising a layer of an imide resin and conductive particles or a laminate having the above-mentioned layer as the outermost layer. When the common logarithm value of the surface resistivity of the outer peripheral surface of the above-mentioned layer measured using a circular probe under the conditions of applied voltage 100 V, applied time 3 seconds, and load 1 kg is x (logΩ / □), and the common logarithm value of the volume resistivity of the above-mentioned layer measured using a circular probe under the conditions of applied voltage 100 V, applied time 5 seconds, and load 1 kg is y (logΩ·cm), the value of y / x is greater than 0.8992 and less than 1.0157.

[0011] According to the second aspect of the present invention, the number average primary particle size of the conductive particles is 10 nm or more and 20 nm or less.

[0012] According to a third aspect of the present invention, the number average primary particle size of the conductive particles is 10 nm or more and 15 nm or less.

[0013] According to a fourth aspect of the present invention, the conductive particles are carbon black having a pH of 2.0 to 3.0.

[0014] According to a fifth aspect of the present invention, the carbon black is channel black.

[0015] According to a sixth aspect of the present invention, the value of x is 9.0 or more and 13.0 or less.

[0016] According to a seventh aspect of the present invention, the value of y is 8.2 or more and 13.0 or less.

[0017] According to an eighth aspect of the present invention, the imide-based resin is a polyimide resin.

[0018] According to a ninth aspect of the present invention, the number average secondary particle size of the conductive particles is not less than 1 time and not more than 8 times the number average primary particle size of the conductive particles.

[0019] According to a tenth aspect of the present invention, the endless belt is a single-layer body.

[0020] According to the 11th embodiment of the present invention, a transfer device is provided, which comprises: an intermediate transfer body, which is the above-mentioned endless belt; a primary transfer mechanism, which transfers the toner image formed on the surface of the image retaining body to the surface of the above-mentioned intermediate transfer body for the first time; and a secondary transfer mechanism, which transfers the above-mentioned toner image transferred to the surface of the above-mentioned intermediate transfer body for the second time to the surface of the recording medium.

[0021] According to the 12th embodiment of the present invention, there is provided an image forming device comprising: an image retainer; a charging device for charging the surface of the image retainer; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the image retainer; a developing device for storing a developer containing a toner and developing the electrostatic latent image formed on the surface of the image retainer using the developer to form a toner image; and a transfer device for transferring the toner image to the surface of a recording medium.

[0022] Effects of the Invention

[0023] According to the above-mentioned schemes 1, 8, or 10, an endless belt is provided, which has excellent transferability to embossed paper when used as an intermediate transfer body, compared with a case where the endless belt is a single-layer body comprising an imide resin and conductive particles, and a layer with a y / x value of less than 0.8992 or greater than 1.0157, or a laminate having the above-mentioned layer in the outermost layer.

[0024] According to the second aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper compared to a case where the number average primary particle size of the conductive particles is larger than 20 nm.

[0025] According to the third aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper compared to a case where the number average primary particle size of the conductive particles is larger than 15 nm.

[0026] According to the fourth aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper, compared to a case where the conductive particles are carbon black having a pH greater than 3.0.

[0027] According to the fifth aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper, compared to a case where the conductive particles are furnace black.

[0028] According to the sixth aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper, compared to a case where the value of x is less than 9.0 or greater than 13.0.

[0029] According to the seventh aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper, compared to a case where the value of y is less than 8.2 or greater than 13.0.

[0030] According to the ninth aspect, there is provided an endless belt which, when used as an intermediate transfer member, has excellent transferability to embossed paper compared to a case where the secondary particle size of the conductive particles is greater than 8 times the primary particle size of the conductive particles.

[0031] According to the above-mentioned scheme 11, a transfer device is provided, which has excellent transfer performance to embossed paper compared to a case where an endless belt is used as an intermediate transfer body and the endless belt is a single-layer body containing an imide resin and conductive particles and a layer with a y / x value less than 0.8992 or greater than 1.0157, or a laminate having the above-mentioned layer in the outermost layer.

[0032] According to the above-mentioned scheme 12, an image forming device is provided, which has excellent transferability to embossed paper compared to a case where an endless belt is used as an intermediate transfer body and the endless belt is a single-layer body containing an imide resin and conductive particles and a layer with a y / x value of less than 0.8992 or greater than 1.0157, or a laminate having the above-mentioned layer in the outermost layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0034] The following describes the present embodiment. These descriptions and examples are provided to illustrate the embodiment and are not intended to limit the scope of the embodiment.

[0035] In the numerical ranges recorded in stages in the present embodiment, the upper limit or lower limit recorded in one numerical range can be replaced by the upper limit or lower limit of the numerical range in other stages recorded. In addition, in the numerical ranges recorded in the present embodiment, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiments.

[0036] The term "step" in this embodiment includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step can be achieved.

[0037] While the embodiments of the present invention are described with reference to the accompanying drawings, the configuration of the embodiments is not limited to that shown in the drawings. In addition, the sizes of the components in the drawings are schematic, and the relative sizes of the components are not limited thereto.

[0038] Each component in this embodiment may include two or more corresponding substances. When referring to the amount of each component in the composition in this embodiment, if there are two or more substances corresponding to each component in the composition, unless otherwise stated, it refers to the total amount of the two or more substances present in the composition.

[0039] [Annular belt]

[0040] The annular belt of this embodiment is a single-layer body comprising a layer of imide resin and conductive particles, or a laminate having the above-mentioned layer as the outermost layer. When the common logarithm of the surface resistivity of the outer peripheral surface of the above-mentioned layer measured using a circular probe under the conditions of applied voltage of 100 V, applied time of 3 seconds, and load of 1 kg is x (logΩ / □), and the common logarithm of the volume resistivity of the above-mentioned layer measured using a circular probe under the conditions of applied voltage of 100 V, applied time of 5 seconds, and load of 1 kg is y (logΩ·cm), the value of y / x is greater than 0.8992 and less than 1.0157.

[0041] It should be noted that the conductivity in this specification refers to a volume resistivity of less than 1×10 13 Ωcm.

[0042] Here, the common logarithm value x of the surface resistivity is measured by the following method.

[0043] A micro-ammeter (R8430A, manufactured by Advantest) was used as the resistance measuring instrument, and a UR probe (manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd.) was used as the probe. The common logarithm of the surface resistivity (logΩ / □) of the outer peripheral surface of the endless belt was measured at 18 points, 6 at equal intervals along the circumference, and 3 points at the center and both ends in the width direction, under the conditions of 100V, 3 seconds, and 1kgf. The average value was calculated. The measurements were performed in an environment of 22°C and 55% RH.

[0044] The common logarithm value y of the volume resistivity is measured by the following method.

[0045] A micro-ammeter (R8430A manufactured by Advantest) was used as the resistance measuring instrument, and a UR probe (manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd.) was used as the probe. The common logarithm of the volume resistivity (logΩ·cm) was measured at 18 points, 6 at equal intervals along the circumference of the endless belt and 3 points at the center and both ends in the width direction, for a total of 100 V, for 5 seconds, and under a pressure of 1 kgf. The average value was calculated. The measurements were performed in an environment of 22°C and 55% RH.

[0046] In this embodiment, by including an imide resin and conductive particles in a single layer or the outermost layer and having a y / x ratio of 0.8992 to 1.0157, excellent transferability to embossed paper is achieved when an endless belt is used as an intermediate transfer member. The reason for this is not yet clear, but is presumed as follows.

[0047] In an image forming apparatus using an endless belt as an intermediate transfer body, when using embossed paper as a recording medium, the following may occur: when transferring a toner image from the intermediate transfer body to the recording medium, the intermediate transfer body may not be able to follow the convex and concave surfaces of the recording medium, resulting in reduced transferability and white spots in the image.

[0048] Specifically, for example, in the secondary transfer region, toner charge may flow outward in the thickness direction of the intermediate transfer member. This can reduce the toner charge level, making transfer particularly difficult in the concave portions of the recording medium. Furthermore, since a sufficient transfer electric field is difficult to form in the concave portions of the recording medium, increasing the electric field during transfer can locally apply an excessive electric field to the convex portions of the recording medium, causing abnormal discharge. This can reduce transferability due to a reduction in toner charge level or reverse charging.

[0049] In contrast, in this embodiment, the single layer or outermost layer comprises an imide resin and conductive particles, and the y / x value is 0.8992 or higher and 1.0157 or lower. That is, while conventional layers comprising imide resins and conductive particles often have a lower volume resistivity than their surface resistivity, the single layer or outermost layer in this embodiment achieves a layer with a lower surface resistivity and a higher volume resistivity than conventional layers. This is believed to suppress the outflow of toner charge in the secondary transfer region toward the thickness of the intermediate transfer element, thereby suppressing any degradation in transferability caused by a decrease in toner charge.

[0050] Furthermore, it is believed that in a layer comprising an imide resin and conductive particles, and having a y / x value within the above-mentioned range, the surface resistivity can be kept low by finely dispersing the conductive particles on the outer peripheral surface, and the distribution of the conductive particles in the thickness direction of the layer can be reduced, thereby improving the volume resistivity. Therefore, it is believed that even if the intermediate transfer element cannot follow the unevenness of the recording medium and an excessive electric field is locally applied to the convex portions of the embossed paper, small discharges will occur at each of the finely dispersed conductive points on the outer peripheral surface of the endless belt, dispersing the current. This reduces the charge of the toner due to abnormal discharge and suppresses reverse charging, thereby improving transferability.

[0051] For the above reasons, it can be inferred that in this embodiment, by making the single layer or the outermost layer contain an imide resin and conductive particles, and the y / x value is greater than or equal to 0.8992 and less than or equal to 1.0157, when the endless belt is used as an intermediate transfer body, the transfer property to the embossed paper is excellent.

[0052] The endless belt may be a single-layer body or a laminated body.

[0053] When the endless belt is a single-layer body, the single-layer body is a layer containing an imide-based resin and conductive particles, and having a y / x value of 0.8992 or more and 1.0157 or less.

[0054] When the endless belt is a laminate, the laminate comprises, for example, a base layer and a surface layer provided on the base layer. The surface layer is the outermost layer of the endless belt. The laminate may have other layers between the base layer and the surface layer.

[0055] When the endless belt is a laminate comprising a base layer and a surface layer, the surface layer comprises an imide resin and conductive particles, and has a y / x ratio of 0.8992 to 1.0157. The base layer is not particularly limited, and examples thereof include a layer comprising a base layer resin and conductive particles.

[0056] Hereinafter, a layer of the endless belt as a single layer will be referred to as a "single layer." Furthermore, a surface layer comprising an imide resin and conductive particles in the endless belt as a laminate will be referred to as a "first layer," and a base layer comprising a base layer resin and conductive particles will be referred to as a "second layer." Furthermore, the imide resin and conductive particles contained in the single layer or first layer will be referred to as the "first resin" and "first conductive particles," respectively, and the base layer resin and conductive particles contained in the second layer will be referred to as the "second resin" and "second conductive particles," respectively.

[0057] <Resin>

[0058] The first resin, an imide-based resin, contained in the single layer or the first layer is a resin containing structural units having imide bonds. Examples thereof include polyimide resins (PI resins) and polyamide-imide resins (PAI resins). From the perspectives of mechanical strength and dispersibility of the first conductive particles, the first resin is more preferably a polyimide resin. The first resin may be composed of a single resin or a mixture of two or more resins.

[0059] Examples of the second resin contained in the second layer include polyimide resin (PI resin), polyamideimide resin (PAI resin), aromatic polyetheretherketone resin, polyphenylene sulfide resin (PPS resin), polyetherimide resin (PEI resin), polyester resin, polyamide resin, and polycarbonate resin.

[0060] The second resin may be composed of a single resin or a mixture of two or more resins.

[0061] When the endless belt has a first layer and a second layer, the first resin and the second resin may be the same resin or different resins, but are preferably the same resin (for example, the first resin and the second resin are both polyimide resins).

[0062] (Polyimide resin)

[0063] As a polyimide resin, the imide compound of the polyamic acid (precursor of a polyimide resin) which is a polymer of tetracarboxylic dianhydride and a diamine compound is mentioned, for example.

[0064] Examples of the polyimide resin include resins having a structural unit represented by the following general formula (I).

[0065] [Chemistry 1]

[0066]

[0067] In the general formula (I), R 1 Represents a 4-valent organic group, R 2 represents a divalent organic group.

[0068] As R 1 The tetravalent organic group represented by the present invention includes an aromatic group, an aliphatic group, a cycloaliphatic group, a group formed by combining an aromatic group and an aliphatic group, or a group formed by substituted aromatic group and aliphatic group. Specifically, the tetravalent organic group includes, for example, the residue of tetracarboxylic dianhydride described below.

[0069] As R 2 Examples of the divalent organic group include aromatic groups, aliphatic groups, cycloaliphatic groups, groups formed by combining aromatic and aliphatic groups, and groups formed by substituting these groups. Specific examples of the divalent organic group include residues of diamine compounds described below.

[0070] Specific examples of the tetracarboxylic dianhydride used as a raw material for the polyimide resin include pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, and ethylenetetracarboxylic dianhydride.

[0071] Specific examples of the diamine compound used as a raw material for the polyimide resin include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-diphenylenediamine, benzidine, 3,3'-dimethylbenzidine, 3 ,3'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl propane, 2,4-bis(β-amino tert-butyl) toluene, bis(p-β-amino-tert-butylphenyl) ether, bis(p-β-methyl-δ-aminophenyl) benzene, bis-p-(1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-phenylenediamine, p-phenylenediamine, di(p-aminocyclohexyl)methane, 1,6-hexanediamine, seven Methylenediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis(3-aminopropoxyethane), 2,2-dimethylpropylenediamine, 3-methoxy-1,6-hexanediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methyl-1,9-nonanediamine, 2,17-diamino 2,17-diaminoeicosane (2,17-diaminoeicosane), 1,4-cyclohexanediamine, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, piperazine, H2N(CH2)3O(CH2)2O(CH2)NH2, H2N(CH2)3S(CH2)3NH2, H2N(CH2)3N(CH3)2(CH2)3NH2, etc.

[0072] (Polyamide-imide resin)

[0073] Examples of the polyamide-imide resin include resins having an imide bond and an amide bond in a repeating unit.

[0074] More specifically, examples of the polyamide-imide resin include polymers of a trivalent carboxylic acid compound (also referred to as tricarboxylic acid) having an acid anhydride group and a diisocyanate compound or a diamine compound.

[0075] As the tricarboxylic acid, trimellitic anhydride and its derivatives are preferred. In addition to the tricarboxylic acid, tetracarboxylic dianhydride, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, etc. may be used in combination.

[0076] Examples of the diisocyanate compound include 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, and naphthalene-2,6-diisocyanate.

[0077] Examples of the diamine compound include compounds having the same structure as the above-mentioned isocyanate and having an amino group instead of an isocyanate group.

[0078] From the perspective of adjusting mechanical strength and volume resistivity, the content of the first resin relative to the entire monolayer is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and further preferably 75% by mass or more and 90% by mass or less.

[0079] From the perspective of adjusting mechanical strength and volume resistivity, the content of the first resin relative to the entire first layer is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and further preferably 75% by mass or more and 90% by mass or less.

[0080] From the perspective of adjusting mechanical strength and volume resistivity, the content of the second resin relative to the entire second layer is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and further preferably 75% by mass or more and 90% by mass or less.

[0081] <Conductive Particles>

[0082] Examples of the first conductive particles contained in a single layer or the first layer include carbon black, metals (such as aluminum, nickel, etc.), metal oxides (such as yttrium oxide, tin oxide, etc.), and ion conductive materials (such as potassium titanate, LiCl, etc.). Among them, carbon black is preferred.

[0083] These conductive particles may be used alone or in combination of two or more.

[0084] Examples of carbon black include Ketjen black, oil furnace black, channel black (ie, gas black), and acetylene black. Surface-treated carbon black (hereinafter also referred to as "surface-treated carbon black") may be used as carbon black.

[0085] Surface-treated carbon black is obtained by imparting groups such as carboxyl groups, quinone groups, lactone groups, and hydroxyl groups to its surface. Examples of surface treatment methods include: air oxidation in which the carbon black is exposed to air in a high-temperature atmosphere for reaction; a reaction with nitrogen oxides or ozone at room temperature (e.g., 22°C); and a method in which the carbon black is oxidized in air in a high-temperature atmosphere and then oxidized with ozone at a low temperature.

[0086] Among these, the conductive particles may be channel black, and particularly acidic carbon black having a pH of 5.0 or less.

[0087] Examples of acidic carbon black include carbon black having its surface oxidized, for example, carbon black having a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like added to its surface.

[0088] As acidic carbon black, from the perspective of improving the transferability to embossed paper, carbon black with a pH of less than 4.5 is preferred, acidic carbon black with a pH of less than 4.0 is more preferred, acidic carbon black with a pH of less than 3.0 is further preferred, acidic carbon black with a pH of 2.0 to 3.0 is particularly preferred, and acidic carbon black with a pH of 2.0 to 2.8 is extremely preferred.

[0089] The pH of acidic carbon black is a value measured by the pH measurement method specified in JIS Z8802 (2011).

[0090] The number-average primary particle size of the first conductive particles may be, for example, 20 nm or less. From the perspective of adjusting y / x within the aforementioned range, the number-average primary particle size is preferably 18 nm or less, more preferably 15 nm or less, and even more preferably 13 nm or less. Furthermore, the number-average primary particle size of the first conductive particles may be, for example, 2 nm or greater. From the perspective of adjusting y / x within the aforementioned range, the number-average primary particle size is preferably 5 nm or greater, and more preferably 10 nm or greater.

[0091] The number average primary particle size of the conductive particles is measured by the following method.

[0092] First, a 100 nm thick sample was taken from each layer of the resulting tape using a microtome and observed using a transmission electron microscope (TEM). The diameter of a circle equal to the projected area of 50 conductive particles (i.e., the equivalent circle diameter) was then used as the particle size, and the average of these values was taken as the number-average primary particle size.

[0093] The number average secondary particle size of the first conductive particles is, for example, in the range of 13 nm to 100 nm. From the perspective of adjusting y / x to the above range, the range of 13 nm to 55 nm is preferred, and the range of 13 nm to 40 nm is more preferred.

[0094] In addition, from the perspective of adjusting y / x to the above range, the number-average secondary particle size of the first conductive particles is preferably 1 times or more and 8 times or less of the number-average primary particle size of the first conductive particles, more preferably 1 times or more and 5 times or less, further preferably 1 times or more and 4.5 times or less, particularly preferably 1 times or more and 3.5 times or less, and extremely preferably 1 times or more and 3 times or less.

[0095] The number average secondary particle size of the conductive particles is determined by observing the outer peripheral surface of the endless belt at 20,000x magnification using a scanning electron microscope (e.g., Hitachi High-Technologies, Model: SU8010). The resulting 256-level grayscale image is binarized with a threshold of 128, and the number average secondary particle size is determined from the image. Specifically, the average diameter of 50 circles having the same projected area as the conductive particle aggregates (i.e., equivalent circle diameters) is used as the number average secondary particle size.

[0096] Note that the number-average secondary particle size of the conductive particles is calculated by calculating the average value including the equivalent circle diameters of the primary particles that exist independently and without aggregation. In other words, when all conductive particles exist independently and without aggregation, the number-average secondary particle size of the conductive particles is 1 times the number-average primary particle size.

[0097] From the perspective of ensuring resistance performance and surface dispersibility, the content of the first conductive particles relative to the entire monolayer is preferably 10 mass % to 50 mass %, more preferably 12 mass % to 40 mass %, further preferably 14 mass % to 30 mass %, and particularly preferably 15 mass % to 20 mass %.

[0098] From the perspective of ensuring resistance performance and surface dispersibility, the content of the first conductive particles relative to the entire first layer is preferably 10 mass % to 50 mass %, more preferably 12 mass % to 40 mass %, further preferably 14 mass % to 30 mass %, and particularly preferably 15 mass % to 20 mass %.

[0099] Specific examples of the second conductive particles contained in the second layer include the same particles as those mentioned for the first conductive particles, and preferred embodiments are also the same.

[0100] The number-average primary particle size of the second conductive particles can be, for example, in the range of 2 nm to 40 nm. From the perspectives of dispersibility, mechanical strength, volume resistivity, etc., the range of 20 nm to 40 nm is preferred, the range of 20 nm to 35 nm is more preferred, and the range of 20 nm to 28 nm is further preferred.

[0101] From the perspective of adjusting dispersibility, mechanical strength, and volume resistivity, the content of the second conductive particles relative to the entire second layer is preferably 5 mass % to 40 mass %, more preferably 10 mass % to 30 mass %, and even more preferably 20 mass % to 30 mass %.

[0102] <Other ingredients>

[0103] The single layer, the first layer, and the second layer may each contain other components in addition to the resin and the conductive particles.

[0104] Examples of other components include a conductive agent other than the conductive particles, a filler for improving the strength of the tape, an antioxidant for preventing thermal degradation of the tape, a surfactant for improving fluidity, and a heat-resistant antioxidant.

[0105] When the above-mentioned layer contains other components, the content of the other components is preferably greater than 0 mass% and less than 10 mass%, more preferably greater than 0 mass% and less than 5 mass%, and even more preferably greater than 0 mass% and less than 1 mass%, relative to the total mass of the target layer.

[0106] <Characteristics of Endless Belt>

[0107] (Thickness of the ring belt)

[0108] From the viewpoint of the mechanical strength of the tape, the thickness of a single layer is preferably 60 μm to 120 μm, more preferably 80 μm to 120 μm.

[0109] From the perspective of manufacturing suitability and suppressing discharge, the thickness of the first layer is preferably 1 μm to 40 μm, and more preferably 3 μm to 20 μm.

[0110] From the viewpoint of the mechanical strength of the belt, the thickness of the second layer is preferably 50 μm to 100 μm, more preferably 60 μm to 80 μm.

[0111] When the endless belt has a first layer and a second layer, the ratio of the first layer to the total thickness is preferably 3% to 50%, more preferably 5% to 30%, from the viewpoint of transferability to embossed paper.

[0112] In addition, the film thickness of each layer was measured as follows.

[0113] Specifically, a cross section of the endless belt in the thickness direction is observed using an optical microscope or a scanning electron microscope, the thickness of the layer to be measured is measured at 10 locations, and the average value is defined as the thickness.

[0114] (Volume resistivity and surface resistivity of the ring belt)

[0115] From the perspective of transferability to embossed paper, the common logarithm value y (logΩ·cm) of the volume resistivity in a single layer or the first layer is preferably 8.2 (logΩ·cm) to 13.0 (logΩ·cm), more preferably 8.4 (logΩ·cm) to 12.0 (logΩ·cm), and particularly preferably 10.0 (logΩ·cm) to 11.5 (logΩ·cm).

[0116] From the perspective of transferability to embossed paper, the common logarithm x (logΩ / □) of the surface resistivity of the outer surface in a single layer or the first layer is preferably greater than 9.0 (logΩ / □) and less than 13.0 (logΩ / □), more preferably greater than 9.0 (logΩ / □) and less than 12.0 (logΩ / □), and particularly preferably greater than 10.5 (logΩ / □) and less than 11.5 (logΩ / □).

[0117] When the common logarithm value of the surface resistivity of the outer peripheral surface is within the above range, it is possible to suppress the adhesion of charges to the single layer or the first layer and to suppress the scattering of toner, particularly compared with a case where the surface resistivity is above the above range.

[0118] The value of y / x is 0.8992 to 1.0157, and is preferably 0.9000 to 1.0000, more preferably 0.9300 to 1.0000, and even more preferably 0.9500 to 1.0000, from the viewpoint of transferability to embossed paper.

[0119] There is no particular limitation on the method for making the value of y / x fall within the above range, and examples thereof include: a method of using particles having a small number-average primary particle size as the first conductive particles; a method of using carbon black having a low pH as the first conductive particles; a method of selecting the type of first conductive particles used; a method of adjusting the conditions in the manufacturing process of the endless belt (such as drying conditions, etc.); a method of combining them; and the like.

[0120] <Method for Manufacturing Endless Belt>

[0121] The method for producing the endless belt of the present embodiment is not particularly limited.

[0122] In one example of a method for manufacturing an endless belt, the following steps are performed: a first coating liquid preparation step of preparing a first coating liquid containing a first resin or a precursor thereof, first conductive particles, and a first solvent; a first coating film formation step of applying the first coating liquid to the periphery of a material to be coated to form a first coating film; and a first drying step of drying the first coating film while increasing the temperature of the material to be coated. In addition to the first coating liquid preparation step, the first coating film formation step, and the first drying step, the method for manufacturing an endless belt may also include other steps. As other steps, for example, when a precursor of the first resin is used, a first firing step of firing the first coating film dried in the first drying step may be mentioned.

[0123] When manufacturing an endless belt as a single-layer body, a single layer comprising the first resin and the first conductive particles is formed on the outer peripheral surface of the coated material by undergoing the above-mentioned first coating liquid preparation step, the first coating film formation step, and the first drying step. It should be noted that the single layer can be formed, for example, by preparing pellets comprising the first resin and the first conductive particles and melt-extruding the pellets. Alternatively, the single layer can be formed by integrating two or more layers by repeating the first coating film formation step and the first drying step two or more times. The number of repetitions of the first coating film formation step and the first drying step is not particularly limited and can be two times or three times or more.

[0124] When manufacturing an endless belt as a laminate, for example, by undergoing the above-described first coating liquid preparation step, first coating film formation step, and first drying step, a first layer comprising a first resin and first conductive particles is formed on the outer peripheral surface of the second layer formed on the coated material. Alternatively, the first layer may be formed by integrating two or more layers by repeating the first coating film formation step and the first drying step two or more times, as in the case of the above-described single layer.

[0125] When manufacturing an endless belt as a laminate, the second layer is formed on the outer peripheral surface of the coated material by, for example, the following steps: a second coating liquid preparation step of preparing a second coating liquid containing a second resin or a precursor thereof, second conductive particles, and a second solvent; a second coating film formation step of applying the second coating liquid to the outer periphery of the coated material to form a second coating film; and a second drying step of drying the second coating film. The second layer can also be formed by, for example, preparing pellets containing the second resin and the second conductive particles and melt-extruding the pellets.

[0126] (Coating solution preparation step)

[0127] In the first coating liquid preparation step, a first coating liquid containing a first resin or a precursor thereof, first conductive particles, and a first solvent is prepared. For example, when the first resin is a polyimide resin and the first conductive particles are carbon black, the first coating liquid may be a solution in which carbon black is dispersed and polyamic acid, a precursor of the polyimide resin, is dissolved in the first solvent. Alternatively, when the first resin is a polyamide-imide resin and the first conductive particles are carbon black, the first coating liquid may be a solution in which carbon black is dispersed and the polyamide-imide resin is dissolved in the first solvent.

[0128] As a method for preparing the first coating liquid, dispersion treatment using a pulverizer such as a ball mill or a jet mill is preferred from the viewpoint of pulverizing agglomerates of the first conductive particles and improving the dispersibility of the first conductive particles.

[0129] The first solvent is not particularly limited and may be appropriately determined according to the type of resin used as the first resin, etc. For example, when the first resin is a polyimide resin or a polyamide-imide resin, a polar solvent described below is preferably used as the first solvent.

[0130] Examples of polar solvents include N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), hexamethylenephosphoramide (HMPA), N-methylcaprolactam, N-acetyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone (N,N-dimethylimidazolidinone, DMI). These solvents may be used alone or in combination of two or more.

[0131] In the case of a second coating liquid preparation step, a second coating liquid containing a second resin, second conductive particles, and a second solvent is prepared in the second coating liquid preparation step. The second resin and second conductive particles are as described above, and the preparation method of the second coating liquid and the second solvent are the same as those of the first coating liquid and the first solvent, respectively.

[0132] (Coating film forming step)

[0133] In the first coating film forming step, the first coating liquid is applied to the outer periphery of the material to be coated to form a first coating film.

[0134] As the material to be coated, for example, a cylindrical or columnar mold can be mentioned. The material to be coated can be a material obtained by treating the outer peripheral surface of the above-mentioned mold with a release agent. In the case of manufacturing an endless belt as a single-layer body, in the first coating film forming step, for example, the first coating liquid is directly applied to the outer peripheral surface of the above-mentioned coated material or the coated material treated with a release agent. In the case of manufacturing an endless belt as a laminate, in the first coating film forming step, for example, the first coating liquid is applied to the outer peripheral surface of the coated material on which the second layer or the second coating film is formed.

[0135] Examples of the coating method for the first coating liquid include known methods such as spray coating, spiral coating (flow coating), blade coating, wire rod coating, dip coating, bead coating, air knife coating, and curtain coating.

[0136] In the case of the second coating film forming step, a second coating liquid is applied to the outer periphery of the substrate to form a second coating film. The second coating liquid is applied in the same manner as the first coating liquid.

[0137] (Drying Step)

[0138] In the first drying step, the first coating film formed in the first coating film forming step is dried. The first solvent contained in the first coating film is removed in the first drying step to obtain a single layer or a first layer.

[0139] Examples of a method for drying the first coating film include a method of supplying hot air to the first coating film and a method of heating the material to be coated.

[0140] The hot air velocity on the first coating film surface is, for example, in the range of 0.1 m / s to 50 m / s, preferably in the range of 1 m / s to 40 m / s, and more preferably in the range of 1 m / s to 20 m / s.

[0141] Here, the hot air velocity on the surface of the first coating film was measured as follows: Specifically, a QB-5 adhesive-type air velocity and temperature probe was connected to a MONITOR-N and the output voltage value was converted according to a conversion formula to obtain the hot air velocity.

[0142] The hot air temperature on the surface of the first coating film is, for example, in the range of 100°C to 280°C, preferably in the range of 100°C to 250°C, and more preferably in the range of 110°C to 235°C.

[0143] The hot air temperature on the surface of the first coating film is measured by connecting a thermometer (for example, a K thermocouple manufactured by Graphtec, model: JBS-7115-5M-K) to a data logger manufactured by Graphtec (model: GL240).

[0144] The method for supplying hot air to the surface of the first coating film is not particularly limited, and examples thereof include a method of blowing hot air from a drying furnace toward the surface of the first coating film through a slit nozzle, a method of directly supplying hot air from a drying furnace to the first coating film, etc. Among them, the method using a slit nozzle is preferred because it is easy to control the hot air velocity on the surface of the first coating film.

[0145] It should be noted that when the second drying step is performed, the second coating film formed in the second coating film forming step is dried in the second drying step. The method for drying the second coating film is the same as the method for drying the first coating film. The second drying step may be completed before the first coating film forming step, or the first coating film forming step may be performed before the second drying step, so that the first drying step also serves as part of the second drying step.

[0146] (Firing steps)

[0147] As described above, the method for manufacturing the endless belt may include a first firing step. In the first firing step, the first coating film dried in the first drying step is heated and fired. For example, when the first resin is a polyimide resin, the polyamic acid contained in the first coating film is imidized in the first firing step to obtain a polyimide.

[0148] The heating temperature in the first firing step is, for example, in the range of 150° C. to 450° C., preferably in the range of 200° C. to 430° C. The heating time in the first firing step is, for example, in the range of 20 minutes to 180 minutes, preferably in the range of 60 minutes to 150 minutes.

[0149] It should be noted that when manufacturing an endless belt as a laminate, when forming the second layer through the second coating liquid preparation step, the second coating film formation step, and the second drying step, a second firing step may be performed to fire the second coating film dried in the second drying step. The second firing step may also serve as the first firing step.

[0150] [Transfer device, image forming device]

[0151] The transfer device of this embodiment includes: an intermediate transfer body; a primary transfer mechanism that transfers the toner image formed on the surface of the image retaining body to the surface of the intermediate transfer body for the first time; and a secondary transfer mechanism that transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time, and the transfer device of this embodiment uses the above-mentioned endless belt as the intermediate transfer body.

[0152] The image forming device of this embodiment includes: an image holder; a charging device for charging the surface of the above-mentioned image holder; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the above-mentioned image holder; a developing device for storing a developer containing a toner, and using the above-mentioned developer to develop the electrostatic latent image formed on the surface of the above-mentioned image holder to form a toner image; and a transfer device for transferring the above-mentioned toner image to the surface of a recording medium, and the image forming device of this embodiment uses the above-mentioned transfer device as a transfer device.

[0153] An example of the image forming apparatus according to the present embodiment will be described below with reference to the drawings.

[0154] Figure 1 Schematic diagram showing the configuration of the image forming apparatus according to this embodiment.

[0155] It should be noted that the aforementioned endless belt is used as the intermediate transfer belt.

[0156] In the image forming apparatus of the present embodiment, for example, at least a portion including the transfer device may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus.

[0157] like Figure 1 As shown, the image forming apparatus 100 of this embodiment is, for example, an intermediate transfer type image forming apparatus generally known as a tandem type. It includes: a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components using an electrophotographic method; a primary transfer unit 10 (i.e., a primary transfer area) that sequentially transfers (primarily transfers) the toner images of respective color components formed by the image forming units 1Y, 1M, 1C, and 1K to an intermediate transfer belt 15; a secondary transfer unit 20 (i.e., a secondary transfer area) that collectively transfers (secondarily transfers) the overlapping toner images transferred to the intermediate transfer belt 15 to a sheet of paper K as a recording medium; and a fixing device 60 that fixes the secondary transferred images to the sheet of paper K (an example of a recording medium). The image forming apparatus 100 also includes a control unit 40 that controls the operation of each device (unit).

[0158] Each image forming unit 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photoreceptor 11 (an example of an image holding member) that rotates in the direction of arrow A as an example of an image holding member for holding a toner image formed on the surface.

[0159] Around the photosensitive body 11, there is provided a charger 12 as an example of a charging device for charging the photosensitive body 11, and a laser exposure device 13 as an example of an electrostatic latent image forming device for writing the electrostatic latent image on the photosensitive body 11 (the exposure beam is represented by the symbol Bm in the figure).

[0160] In addition, around the photoreceptor 11, as an example of a developing device, there is provided a developer 14 that stores color component toners and uses the toners to form a visible image from the electrostatic latent image on the photoreceptor 11, and a primary transfer roller 16 that transfers the color component toner images formed on the photoreceptor 11 to the intermediate transfer belt 15 using the primary transfer section 10.

[0161] Furthermore, a photoreceptor cleaner 17 is provided around the photoreceptor 11 to remove residual toner from the photoreceptor 11. Electrophotographic components, including a charger 12, a laser exposure unit 13, a developer 14, a primary transfer roller 16, and the photoreceptor cleaner 17, are arranged in this order along the rotational direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a roughly linear arrangement, starting from the upstream side of the intermediate transfer belt 15, in the order of yellow (Y), magenta (M), cyan (C), and black (K).

[0162] The intermediate transfer belt 15 as an intermediate transfer member has a volume resistivity of, for example, 1×10 6 Ωcm or more 1×10 14 The thickness is formed to be less than Ωcm, for example, about 0.1mm.

[0163] The intermediate transfer belt 15 is formed by various rollers. Figure 1 The intermediate transfer belt 15 is cyclically driven (rotated) in the direction B shown at a speed suitable for the purpose. The various rollers include the following: a drive roller 31 driven by a motor (not shown) with excellent constant speed to rotate the intermediate transfer belt 15; a support roller 32 supporting the intermediate transfer belt 15, extending substantially linearly along the arrangement direction of the photoreceptors 11; a tensioning roller 33 applying tension to the intermediate transfer belt 15 and functioning as a correction roller to prevent the intermediate transfer belt 15 from meandering; a back roller 25 provided in the secondary transfer section 20; and a cleaning back roller 34 provided in the cleaning section to scrape off residual toner from the intermediate transfer belt 15.

[0164] The primary transfer unit 10 comprises primary transfer rollers 16 disposed opposite the photoreceptors 11, sandwiching an intermediate transfer belt 15 therebetween. The primary transfer rollers 16 are placed in pressure contact with the photoreceptors 11, sandwiching the intermediate transfer belt 15 therebetween. A voltage (primary transfer bias) with a polarity opposite to the toner charge polarity (negative polarity, the same applies hereinafter) is applied to the primary transfer rollers 16. This electrostatic attraction causes the toner images on the respective photoreceptors 11 to be sequentially transferred to the intermediate transfer belt 15, resulting in the formation of overlapping toner images on the intermediate transfer belt 15.

[0165] The secondary transfer section 20 includes a back roller 25 and a secondary transfer roller 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 .

[0166] The back roller 25 has a surface resistivity of 1×10 7 Ω / □ or more 1×10 10 The back roller 25 is arranged on the back side of the intermediate transfer belt 15 and serves as a counter electrode for the secondary transfer roller 22. The back roller 25 is arranged in contact with the metal power supply roller 26 that stably applies the secondary transfer bias.

[0167] On the other hand, the secondary transfer roller 22 has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 The secondary transfer roller 22 is placed in pressure contact with the back roller 25, sandwiching the intermediate transfer belt 15. Furthermore, the secondary transfer roller 22 is grounded, and a secondary transfer bias is applied between the secondary transfer roller 22 and the back roller 25, thereby performing a secondary transfer of the toner image onto the paper K conveyed to the secondary transfer section 20.

[0168] Note that, as an example, the conveyance speed of the paper K in the secondary transfer section 20 is in the range of 50 mm / s to 60 mm / s.

[0169] In addition, an intermediate transfer belt cleaner 35 is provided on the downstream side of the secondary transfer section 20 of the intermediate transfer belt 15 so as to be detachable from the intermediate transfer belt 15 . The intermediate transfer belt cleaner 35 removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15 .

[0170] It should be noted that the intermediate transfer belt 15 , the primary transfer section 10 (primary transfer roller 16 ), and the secondary transfer section 20 (secondary transfer roller 22 ) correspond to an example of a transfer device.

[0171] On the other hand, a reference sensor (home position sensor) 42 is provided upstream of the yellow image forming unit 1Y. This reference sensor (home position sensor) 42 generates a reference signal that serves as a reference for controlling the image formation timing in each of the image forming units 1Y, 1M, 1C, and 1K. Furthermore, an image density sensor 43 for image quality adjustment is provided downstream of the black image forming unit 1K. This reference sensor 42 is configured to recognize a mark provided on the back side of the intermediate transfer belt 15 and generate a reference signal. Based on the recognition of this reference signal, each of the image forming units 1Y, 1M, 1C, and 1K starts image formation in response to an instruction from the control unit 40.

[0172] Furthermore, in the image forming apparatus of the present embodiment, as a conveying mechanism for conveying paper K, there is provided: a paper storage section 50 for storing paper K; a paper feed roller 51 for taking out and conveying the paper K accumulated in the paper storage section 50 at a predetermined timing; a conveying roller 52 for conveying the paper K sent out by the paper feed roller 51; a conveying guide 53 for conveying the paper K conveyed by the conveying roller 52 into the secondary transfer section 20; a conveying belt 55 for conveying the paper K conveyed after the secondary transfer by the secondary transfer roller 22 to the fixing device 60; and a fixing entrance guide 56 for introducing the paper K into the fixing device 60.

[0173] Next, a basic image forming process of the image forming apparatus of this embodiment will be described.

[0174] In the image forming apparatus of this embodiment, image data outputted from an image reading device or a personal computer (PC) (not shown) is processed by an image processing device (not shown), and then image forming is performed by the image forming units 1Y, 1M, 1C, and 1K.

[0175] The image processing device performs image processing on the input reflectance data, including shading correction, positional offset correction, brightness / color space conversion, gamma correction, frame removal, color editing, motion editing, and other image editing processes. The processed image data is converted into colorant grayscale data for the four colors of Y, M, C, and K, and is output to the laser exposure device 13.

[0176] In the laser exposure device 13, exposure beams Bm, emitted from, for example, a semiconductor laser, are irradiated onto the photoreceptors 11 of the image forming units 1Y, 1M, 1C, and 1K based on the input color tone data. After the surfaces of the photoreceptors 11 of the image forming units 1Y, 1M, 1C, and 1K are charged by the charger 12, the surfaces are scanned and exposed by the laser exposure device 13, forming electrostatic latent images. The formed electrostatic latent images are developed by the image forming units 1Y, 1M, 1C, and 1K as toner images of the respective colors Y, M, C, and K.

[0177] The toner images formed on the photoreceptors 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 at the primary transfer section 10, where each photoreceptor 11 contacts the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) having a polarity opposite to the toner charge polarity (negative polarity) is applied to the substrate of the intermediate transfer belt 15 by the primary transfer roller 16. The toner images are then sequentially superimposed on the surface of the intermediate transfer belt 15, thereby performing the primary transfer.

[0178] After the toner images are sequentially transferred primarily to the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 is moved to transport the toner images to the secondary transfer section 20. When transporting the toner images to the secondary transfer section 20, the transport mechanism rotates the paper feed roller 51 according to the timing of the toner image transport to the secondary transfer section 20, and supplies paper K of the desired size from the paper storage section 50. The paper K supplied by the paper feed roller 51 is transported by the transport roller 52 and, via the transport guide 53, reaches the secondary transfer section 20. Before reaching the secondary transfer section 20, the paper K is temporarily stopped, and the registration rollers (not shown) are rotated according to the timing of the movement of the intermediate transfer belt 15 carrying the toner images. This allows the position of the paper K to be aligned with the position of the toner images. Even when using paper with an uneven surface, such as embossed paper, as the paper K, good transfer performance can be achieved.

[0179] In the secondary transfer section 20, the secondary transfer roller 22 is pressed against the back roller 25 via the intermediate transfer belt 15. At this point, the paper K, which is being transported according to timing, is sandwiched between the intermediate transfer belt 15 and the secondary transfer roller 22. At this point, when a voltage (secondary transfer bias) having the same polarity as the toner's charging polarity (negative polarity) is applied by the power supply roller 26, a transfer electric field is formed between the secondary transfer roller 22 and the back roller 25. The unfixed toner image on the intermediate transfer belt 15 is then electrostatically transferred onto the paper K in the secondary transfer section 20, where the secondary transfer roller 22 and the back roller 25 are pressed.

[0180] Thereafter, the sheet K onto which the toner image has been electrostatically transferred is conveyed by the secondary transfer roller 22 while being directly separated from the intermediate transfer belt 15, and is then conveyed to a conveyor belt 55 located downstream of the secondary transfer roller 22 in the sheet conveying direction. Along the conveyor belt 55, the sheet K is conveyed to the fixing device 60 at an optimal conveying speed. The unfixed toner image on the sheet K conveyed to the fixing device 60 undergoes a fixing process under heat and pressure in the fixing device 60, thereby being fixed to the sheet K. The sheet K, on which the fixed image has been formed, is then conveyed to a discharged paper storage unit (not shown) provided in the discharge section of the image forming apparatus.

[0181] On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning section as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the cleaning back roller 34 and the intermediate transfer belt cleaner 35 .

[0182] Although the present embodiment has been described above, it should be understood that the present invention is not limited to the above embodiment, and various modifications, changes, and improvements may be made.

[0183] Example

[0184] The following describes examples of the present invention, but the present invention is not limited to the following examples. It should be noted that in the following description, "parts" and "%" are all based on mass unless otherwise specified.

[0185] [Example 1]

[0186] ―Preparation of coating solution―

[0187] To an N-methyl-2-pyrrolidone (NMP) solution of polyamic acid formed from 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether (the solid content after imide conversion is 18% by mass), carbon black particles (channel black, FW200, manufactured by Orion Engineered Carbons) are added in an amount of 19.0 parts by mass relative to 100 parts by mass of the solid content of the polyamic acid, mixed and stirred, thereby preparing a coating liquid 1 as a carbon black-dispersed polyimide precursor solution.

[0188] -Production of the intermediate transfer belt-

[0189] An aluminum cylinder having an outer diameter of 278 mm and a length of 600 mm was prepared.

[0190] While the aluminum cylinder was being rotated, the coating liquid 1 was discharged onto the outer surface of the aluminum cylinder with a width of 500 mm by a dispenser to form a coating film with a thickness of 80 μm.

[0191] The aluminum cylinder with the coating film formed thereon was then heated and dried at 140° C. for 30 minutes while being placed horizontally, and then heated for 120 minutes to a maximum temperature of 320° C., thereby obtaining an endless belt.

[0192] Then, the axial center portion of the endless belt was cut into a width of 363 mm to obtain the intermediate transfer belt 1 .

[0193] [Example 2]

[0194] In the preparation of the coating liquid, an intermediate transfer belt 2 was obtained in the same manner as in Example 1 except that the amount of carbon black particles added was changed from 19.0 parts by mass to 17.5 parts by mass.

[0195] [Example 3]

[0196] In the preparation of the coating liquid, an intermediate transfer belt 3 was obtained in the same manner as in Example 1 except that the amount of carbon black particles added was changed from 19.0 parts by mass to 20.0 parts by mass.

[0197] [Example 4]

[0198] In the preparation of the coating liquid, an intermediate transfer belt 4 was obtained in the same manner as in Example 1 except that 14.0 parts by mass of carbon black particles (channel black, FW285, manufactured by Orion Engineered Carbons) were added instead of 19.0 parts by mass of carbon black particles (FW200).

[0199] [Example 5]

[0200] In the preparation of the coating liquid, an intermediate transfer belt 5 was obtained in the same manner as in Example 1 except that 14.0 parts by mass of carbon black particles (channel black, FW182, manufactured by Orion Engineered Carbons) were added instead of 19.0 parts by mass of carbon black particles (FW200).

[0201] [Example 6]

[0202] An intermediate transfer belt 6 was obtained in the same manner as in Example 1 except that the amount of carbon black particles added was changed from 19.0 parts by mass to 20.1 parts by mass in the preparation of the coating liquid.

[0203] [Example 7]

[0204] An intermediate transfer belt 7 was obtained in the same manner as in Example 1 except that the amount of carbon black particles added was changed from 19.0 parts by mass to 17.4 parts by mass in the preparation of the coating liquid.

[0205] [Comparative Example 1]

[0206] In the preparation of the coating liquid, an intermediate transfer belt C1 was obtained in the same manner as in Example 1 except that 27.5 parts by mass of carbon black particles (channel black, Special Black 4, manufactured by Orion Engineered Carbons) were added instead of 19.0 parts by mass of carbon black particles (FW200).

[0207] [Measurement of Intermediate Transfer Belt]

[0208] The common logarithm value x (logΩ / □) of the surface resistivity and the common logarithm value y (logΩ·cm) of the volume resistivity of the obtained intermediate transfer belt were determined by the above-mentioned methods. The results are shown in Table 1.

[0209] Table 1 also shows the layer structure of the endless belt, the number average primary particle size (nm) of the carbon black particles used, and the pH of the carbon black particles used.

[0210] The number average secondary particle size R of the conductive particles (carbon black particles) obtained was determined by the above method, and the ratio (R / r) to the number average primary particle size r was calculated.

[0211] [Evaluation of Intermediate Transfer Belt]

[0212] <Evaluation of Transferability to Concave and Concave Paper>

[0213] The obtained intermediate transfer belt is attached to a built-in image forming device (Iridesse TM Image quality evaluation was performed on the intermediate transfer belt in Production Press (manufactured by Fuji Xerox Corporation).

[0214] The image quality evaluation was conducted using embossed paper (Lesac 66, 250 gsm) and a K color (ie, black) halftone 60% solid image. The evaluation criteria are as follows, and the results are shown in Table 1.

[0215] -Evaluation Criteria-

[0216] A: There is almost no white space in the concave part of the paper

[0217] B: There is a slight white spot in the concave part of the paper

[0218] C: About half of the concave part of the paper is exposed

[0219] D: Most of the concave part of the paper is white.

[0220] [Table 1]

[0221]

[0222] As can be seen from the results shown in Table 1, the belt of this example has excellent transferability compared to the belt of the comparative example even when a recording medium having a large surface irregularity is used.

Claims

1. An endless belt, which is a single-layer body or a laminated body, The layer of the monolayer body comprises an imide resin and conductive particles; when the common logarithm value of the surface resistivity of the outer peripheral surface of the layer measured using a ring probe under the conditions of an applied voltage of 100 V, an applied time of 3 seconds, and a load of 1 kg is x log Ω / □, and the common logarithm value of the volume resistivity of the layer measured using a ring probe under the conditions of an applied voltage of 100 V, an applied time of 5 seconds, and a load of 1 kg is y log Ω·cm, the value of y / x is 0.9500 or more and 1.0157 or less; The above-mentioned laminate has the above-mentioned layer as the outermost layer.

2. The endless belt according to claim 1, wherein The number average primary particle size of the conductive particles is 10 nm or more and 20 nm or less.

3. The endless belt according to claim 2, wherein: The number average primary particle size of the conductive particles is 10 nm or more and 15 nm or less.

4. The endless belt according to any one of claims 1 to 3, wherein The conductive particles are carbon black having a pH of 2.0 to 3.

0.

5. The endless belt according to claim 4, wherein The carbon black mentioned above is channel black.

6. The endless belt according to claim 1, wherein The value of x is 9.0 or more and 13.0 or less.

7. The endless belt according to claim 1, wherein The value of y is 8.2 or more and 13.0 or less.

8. The endless belt according to claim 1, wherein The above-mentioned imide-based resin is a polyimide resin.

9. The endless belt according to claim 1, wherein The number average secondary particle size of the conductive particles is not less than 1 time and not more than 8 times the number average primary particle size of the conductive particles.

10. The endless belt according to claim 1, wherein The endless belt is a single-layer body.

11. A transfer device comprising: An intermediate transfer member, which is an endless belt according to any one of claims 1 to 10, a primary transfer mechanism for primarily transferring the toner image formed on the surface of the image holding member to the surface of the intermediate transfer member; and The secondary transfer mechanism secondarily transfers the toner image transferred to the surface of the intermediate transfer member to the surface of a recording medium.

12. An image forming apparatus comprising: Image holding body, A charging device for charging the surface of the image holding member. An electrostatic latent image forming device forms an electrostatic latent image on the charged surface of the image holding member. a developing device storing a developer containing a toner, and developing the electrostatic latent image formed on the surface of the image holding member using the developer to form a toner image; and The transfer device according to claim 11 transfers the toner image to the surface of a recording medium.

Images