Endless belt, transfer apparatus, and image forming apparatus

Abstract

To provide an endless belt that is excellent in transferability to rugged paper when applied as an intermediate transfer body.SOLUTION: An endless belt has a layer including resin and conductive particles, and when voltage is applied to the layer, the break-down voltage of the endless belt from the application of voltage to the start of discharge is 0.9 kV or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In image forming devices using the electrophotographic method (such as photocopiers, facsimile machines, and printers), a toner image formed on the surface of an image holder is transferred to the surface of a recording medium and fixed onto the recording medium to form an image. For this transfer of the toner image to the recording medium, a conductive endless belt, such as an intermediate transfer belt, is used.

[0003] For example, Patent Document 1 discloses "an intermediate transfer belt having at least a surface layer on a substrate, characterized in that the surface layer contains aggregates of conductive particles with an average particle diameter of 0.5 to 25 μm."

[0004] Patent Document 2 discloses "an intermediate transfer belt having at least a surface layer on a substrate, characterized in that the surface layer contains metal-coated resin fine particles." [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-011117 [Patent Document 2] Japanese Patent Publication No. 2007-078789 [Overview of the project] [Problems that the invention aims to solve]

[0006] In a transfer device that uses an endless belt as an intermediate transfer body, if a recording medium with large surface irregularities, such as embossed paper (hereinafter also referred to as "uneven paper"), is used, the intermediate transfer body may not be able to follow the irregularities of the recording medium when transferring the toner image from the intermediate transfer body to the recording medium, resulting in reduced transferability and the appearance of white spots in the image. The object of the present invention is to provide an endless belt having a layer containing resin and conductive particles, which exhibits superior transferability to uneven paper when applied as an intermediate transfer material, compared to cases where the discharge initiation voltage from voltage application to discharge initiation is less than 0.9 kV or the number average primary particle diameter of the conductive particles exceeds 11 nm. [Means for solving the problem]

[0007] The above problems will be solved by the following means. <1> It has a layer containing resin and conductive particles, An endless belt in which, when a voltage is applied to the aforementioned layer, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9kV or higher. <2> The number-average primary particle diameter of the conductive particles is 11 nm or less. <1> The endless belt described above. <3> The number-average primary particle diameter of the conductive particles is 8 nm or more and 10 nm or less. <2> The endless belt described above. <4> It has a layer containing resin and conductive particles, An endless belt in which the number-average primary particle diameter of the conductive particles is 11 nm or less. <5> The conductive particles include conductive carbon particles, <1> ~ <4> An endless belt as described in any one of the following. <6> The content of the conductive particles is 10% by mass or more and 30% by mass or less relative to the total solid content of the layer. <1> ~ <5> An endless belt as described in any one of the following. <7> Polyester resin particles with a volume-average particle diameter of 4.7 μm are applied to the outer surface under a load of 0 g / cm². 2After adhesion, when air is blown onto the outer surface from above the outer surface while increasing the blowing pressure, if the blowing pressure is 6 kPa or less, all the polyester resin particles attached to the outer surface will separate from the outer surface. <1> ~ <6> An endless belt as described in any one of the following. <8> The layer further comprises a surfactant, <1> ~ <7> An endless belt as described in any one of the following. <9> The amount of the surfactant is 1% by mass or more and 6% by mass or less relative to the total solid content of the layer. <8> The endless belt described above. <10> The surfactant is at least one of an oligomer having a substituent with 6 or fewer carbon atoms and a fluorine atom, and an oligomer having a silicone structure with a methyl group. <8> or <9> The endless belt described above. <11> The oligomer having a substituent with 6 or fewer carbon atoms and a fluorine atom is an oligomer having a perfluoroalkyl structure with 6 or fewer carbon atoms. <10> The endless belt described above. <12> The oligomer has four or more repeating units of monomer. <10> or <11> The endless belt described above. <13> The surface free energy of the outer surface of the endless belt is 47 mN / m or less. <1> ~ <12> An endless belt as described in any one of the following. <14> The water contact angle of the outer surface of the endless belt is 85° or more. <1> ~ <13> An endless belt as described in any one of the following. <15> The diiodomethane contact angle of the outer surface of the endless belt is 40° or more. <1> ~ <14> An endless belt as described in any one of the following. <16> The polyester resin particles are applied to the outer surface under a load of 0 g / cm². 2 and 46g / cm³ 2 After adhesion, air is blown onto the outer surface from above the outer surface while increasing the blowing pressure, and the relationship between the air blowing pressure and the point at which all the polyester resin particles attached to the outer surface are separated from the outer surface satisfies the relationship shown by the following formula (P). <7> The endless belt described above. Formula (P): Spraying pressure P46 / Spraying pressure P0 ≤ 1.5 In formula (P), P0 represents the spraying pressure of the air when all the polyester resin particles adhering to the outer peripheral surface separate from the outer peripheral surface after the polyester resin particles are adhered under a load of 0 g / cm 2 and P46 represents the spraying pressure of the air when all the polyester resin particles adhering to the outer peripheral surface separate from the outer peripheral surface after the polyester resin particles are adhered under a load of 46 g / cm 2 . <17> An intermediate transfer member on which a toner image is transferred to the outer peripheral surface, the intermediate transfer member having the endless belt according to any one of <1> to <16>, A primary transfer device having a primary transfer member for primarily transferring the toner image formed on the surface of the image carrier to the outer peripheral surface of the intermediate transfer member, A secondary transfer device having a secondary transfer member disposed in contact with the outer peripheral surface of the intermediate transfer member for secondarily transferring the toner image transferred to the outer peripheral surface of the intermediate transfer member to the surface of the recording medium, and a transfer device comprising the same. <18> The transfer device according to <17>, wherein the secondary transfer member is a secondary transfer roll and the contact width between the intermediate transfer member and the secondary transfer roll is 0.2 cm or more and 4.0 cm or less. <19> The transfer device according to <18>, wherein the secondary transfer member is a secondary transfer roll and the contact width between the intermediate transfer member and the secondary transfer roll is 0.2 cm or more and 2.8 cm or less. <20> A toner image forming device having an image carrier and forming a toner image on the surface of the image carrier, A transfer device for transferring the toner image formed on the surface of the image carrier to the surface of the recording medium, the transfer device being the transfer device according to any one of <17> to <19>, and an image forming device comprising the same.

Advantages of the Invention

[0008] <1> According to the invention, compared to an endless belt containing resin and conductive particles, in which the discharge initiation voltage from voltage application to discharge initiation is less than 0.9kV when a voltage is applied to the layer, the invention provides an endless belt that exhibits superior transferability to uneven paper when applied as an intermediate transfer material. <2> According to the invention, compared to an endless belt in which the number average primary particle diameter of the conductive particles exceeds 11 nm, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material. <3> According to the invention, compared to an endless belt in which the number average primary particle diameter of the conductive particles is less than 8 nm or greater than 10 nm, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material. <4> According to the invention, compared to an endless belt containing resin and conductive particles, wherein the number average primary particle diameter of the conductive particles exceeds 11 nm, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material. <5> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material, compared to the case where the conductive particles are metal oxide particles. <6> According to the invention, compared to an endless belt in which the conductive particle content is less than 10% by mass or more than 30% by mass relative to the total solid content of the layer, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material. <7> According to the invention, polyester resin particles with a volume-average particle diameter of 4.7 μm are applied to the outer surface under a load of 0 g / cm². 2 When air is blown onto the outer surface from above while increasing the blowing pressure after adhesion, even if the blowing pressure exceeds 6 kPa, the provided endless belt exhibits superior transferability to uneven paper when applied as an intermediate transfer material compared to an endless belt where the polyester resin particles attached to the outer surface remain on the outer surface. <8> According to the invention, compared to a case where the layer consists only of resin and conductive particles, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer body. <9> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper when applied as an intermediate transfer material, compared to cases where the surfactant content is less than 1% by mass or more than 6% by mass relative to the total solid content of the layer.

[0009] <10> , <11> , or <12> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper compared to a surfactant with a monomer structure.

[0010] <13> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper compared to a case where the surface free energy of the outer surface of the endless belt exceeds 47 mN / m. <14> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper compared to a case where the water contact angle of the outer surface of the endless belt exceeds 85°. <15> According to the invention, an endless belt is provided that exhibits superior transferability to uneven paper compared to the case where the diiodomethane contact angle of the outer surface of the endless belt exceeds 40°.

[0011] <16> According to the invention described above, an endless belt is provided that offers superior transferability to uneven paper compared to the case where the spraying pressure P46 / spraying pressure P0 ≥ 1.5.

[0012] <17> According to the invention, when an endless belt containing resin and conductive particles is applied as an intermediate transfer body, wherein the discharge initiation voltage from voltage application to discharge initiation is less than 0.9kV when a voltage is applied to the layer, or the number average primary particle diameter of the conductive particles exceeds 11nm, a transfer device is provided that exhibits excellent transferability to uneven paper. <18> , or <19> According to the present invention, compared to using an endless belt containing resin and conductive particles, wherein the discharge initiation voltage from voltage application to discharge initiation when a voltage is applied to the layer is less than 0.9kV, or an endless belt in which the number average primary particle diameter of the conductive particles exceeds 11nm, a transfer device is provided that exhibits superior transferability to uneven paper even when the contact width between the intermediate transfer body and the secondary transfer member is large, such as 0.2cm to 4.0cm (or 0.2cm to 2.8cm). <20> According to the present invention, an image forming apparatus is provided that exhibits superior transferability to uneven paper compared to an endless belt containing resin and conductive particles, wherein the discharge initiation voltage from voltage application to discharge initiation is less than 0.9kV when a voltage is applied to the layer, or an endless belt in which the number average primary particle diameter of the conductive particles exceeds 11nm, when used as an intermediate transfer body. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 2] This is a schematic diagram showing the area around the secondary transfer section in another example of the image forming apparatus according to this embodiment. [Modes for carrying out the invention]

[0014] The embodiments are described below. These descriptions and examples are illustrative and do not limit the scope of the embodiments.

[0015] In the numerical ranges described in stages within this embodiment, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described within this embodiment, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this embodiment, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. In this embodiment, when describing embodiments with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the members in each figure are conceptual, and the relative relationships between the sizes of the members are not limited thereto. In this embodiment, each component may contain multiple types of the corresponding substance. In this embodiment, when referring to the amount of each component in the composition, if there are multiple types of the substance corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple types of substances present in the composition.

[0016] [Endless belt] The endless belt according to the first embodiment has a layer containing resin and conductive particles, and when a voltage is applied to the layer, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9kV or higher. The endless belt according to the second embodiment is an endless belt having a layer containing resin and conductive particles, wherein the number-average primary particle diameter of the conductive particles is 11 nm or less.

[0017] Hereinafter, a configuration encompassing both the first and second embodiments will also be referred to as "this embodiment."

[0018] The endless belt according to this embodiment, by satisfying the above configuration, exhibits excellent transferability to uneven paper when used as an intermediate transfer body. The reason for this is not entirely clear, but it is presumed to be as follows.

[0019] In an image forming apparatus that uses an endless belt as an intermediate transfer body, if uneven paper is used as the recording medium, the intermediate transfer body may not be able to follow the unevenness of the recording medium when transferring the toner image from the intermediate transfer body to the recording medium, which can lead to a decrease in transferability and the occurrence of white spots in the image. In particular, if the non-electrostatic adhesion force between the outer surface of the endless belt acting as an intermediate transfer body and the toner is strong, then when using textured paper as the recording medium, the transfer performance may decrease and white spots may occur in the image. This is because it becomes difficult for the toner image formed on the outer surface of the intermediate transfer body to come into contact with the recesses of the textured paper.

[0020] Hereinafter, the characteristic that "when a voltage is applied to a layer containing resin and conductive particles, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9kV or higher" will also be referred to as the "electrostatic adhesion characteristic."

[0021] In contrast, the endless belt according to the first embodiment satisfies the electrostatic adhesion characteristics. As a result, the electrostatic adhesion of the layer containing the resin and conductive particles in the endless belt is reduced. Consequently, the electrostatic adhesion between the outer surface of the endless belt and the toner is reduced. Therefore, even when using textured paper as the recording medium, it is believed that the reduction in transferability and the occurrence of white spots in the image are suppressed.

[0022] Furthermore, in the endless belt according to the second embodiment, by using a resin layer containing conductive particles whose number-average primary particle diameter is within the above range, conductive particles with a small number-average primary particle diameter are more likely to exist in the layer with high dispersibility. As a result, the electrostatic adhesion force of the layer containing the resin and conductive particles in the endless belt is reduced. Consequently, the electrostatic adhesion force generated between the outer surface of the endless belt and the toner is reduced. Therefore, even when using textured paper as the recording medium, it is believed that the reduction in transferability and the occurrence of white spots in the image are suppressed.

[0023] The endless belt according to this embodiment will be described in detail below.

[0024] <Discharge initiation voltage> In the endless belt according to the first embodiment, when a voltage is applied to a layer containing resin and conductive particles, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9kV or higher, preferably 0.95kV to 1.5kV, and more preferably 1.0kV to 1.4kV. In the endless belt according to the second embodiment, when a voltage is applied to a layer containing resin and conductive particles, the discharge initiation voltage from the application of voltage to the start of discharge is preferably 0.9kV or higher, more preferably 0.95kV to 1.5kV, and even more preferably 1.0kV to 1.4kV. When the discharge initiation voltage is 0.9kV or higher, the increase in electrostatic adhesion of the layer containing the resin and conductive particles is suppressed, and the electrostatic adhesion generated between the outermost surface of the endless belt and the toner is also reduced. Therefore, it is presumed that the transfer performance to uneven paper is excellent.

[0025] The discharge initiation voltage is measured as follows: First, a 3cm x 4cm square sample containing resin and conductive particles is taken from the target endless belt and used as the test specimen. Next, in an environment of 22°C and 15% humidity, the sample specimen is placed on an electrode, a 60μm thick film is sandwiched in between, and the other electrode is placed on top to set the space gap to 60μm. Then, the applied voltage is increased at 1.67V / s, and the applied voltage at which discharge begins is defined as the discharge start voltage.

[0026] Hereinafter, the characteristic of polyester resin particles adhering to the outer surface separating from the outer surface when the spraying pressure P0 is 6 kPa or less will also be referred to as the "non-electrostatic adhesion characteristic."

[0027] <Non-electrostatic adhesion properties> The endless belt according to this embodiment has polyester resin particles with a volume-average particle diameter of 4.7 μm on its outer surface, and is subjected to a load of 0 g / cm². 2 After adhesion, when air is blown onto the outer surface from above the outer surface while increasing the blowing pressure, all the polyester resin particles attached to the outer surface separate from the outer surface when the blowing pressure is preferably 6 kPa or less (more preferably 4 kPa or less, and even more preferably 2 kPa or less) from the viewpoint of transferability to uneven paper. By satisfying this non-electrostatic adhesion characteristic, the non-electrostatic adhesion force generated between the outer peripheral surface of the endless belt and the toner is reduced, and even when uneven paper is used as the recording medium, the transferability is less likely to decrease and white spots in the image are more effectively suppressed.

[0028] The determination of whether or not the non-electrostatic adhesion characteristic is satisfied is performed as follows. First, a 3 cm × 4 cm square sample piece is taken from the target endless belt. Next, in an environment of 22°C and 15% humidity, on the surface of the sample piece corresponding to the outer peripheral surface of the endless belt, from a height of 15 cm above, with a voltage of 10 kV applied horizontally to the surface corresponding to the outer peripheral surface of the endless belt, polyester resin particles are sprayed and adhered at a loading of 3 g / cm 2 The polyester resin particles are sprayed so as to naturally fall by their own weight from a height of 10 cm or less above the surface corresponding to the outer peripheral surface of the endless belt, and adhered to the surface corresponding to the outer peripheral surface of the endless belt with a load of 0 g / cm 2 Here, the polyester resin particles are a polycondensate of dimethyl fumarate, which is a dicarboxylic acid, and propylene glycol, which is a dialcohol, and resin particles with a weight average molecular weight of 25,000 and a volume average particle diameter of 4.7 μm are applied. The polyester resin particles are resin particles that have substantially no frictional contact with each other or with other members (such as carriers) and have substantially no triboelectrification. Specifically, the polyester resin particles are the resin particles after being stored for six months in an environment of 10°C or higher and 22°C or lower, and 10% RH or higher and 55% RH or lower after production.

[0029] Next, air spraying is started from an air ejection port with a diameter of 0.7 mm located 3 cm above the center of the surface of the sample piece to which the polyester resin particles are adhered, at a spraying pressure of 0.1 kPa, and the spraying pressure is increased at 0.5 kPa / second. Then, when the spraying pressure reaches 6 kPa, if all the polyester resin particles have separated from the sample piece, it is determined that the non-electrostatic adhesion characteristic is satisfied. ​On the other hand, if polyester resin particles remain on the sample even when the spraying pressure exceeds 6 kPa, it is determined that the non-electrostatic adhesion characteristics are not satisfied.

[0030] Here, the weight-average molecular weight of polyester resin particles is measured by gel permeation chromatography (GPC). GPC molecular weight measurement is performed using a Tosoh GPC-HLC-8120GPC measuring device, a Tosoh TSKgel SuperHM-M (15cm) column, and THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from these measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples. Furthermore, the volume-average particle size of the polyester resin particles is measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For measurement, add 0.5 mg to 50 mg of the sample to be measured in 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. Add this to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with diameters between 2 μm and 60 μm is then measured using a Coulter Multisizer II with a 100 μm aperture. The number of particles sampled is 50,000. Based on the measured particle size distribution, the volume is divided into smaller particle size ranges (channels), and a cumulative distribution is drawn from the smallest diameter side. The particle diameter at which the cumulative distribution reaches 50% is defined as the volume-average particle diameter D50v.

[0031] In the endless belt according to this embodiment, the polyester resin particles are applied to the outer surface under a load of 0 g / cm². 2 and 46g / cm³ 2After adhesion, air is blown onto the outer surface from above, increasing the blowing pressure, and it is preferable that the relationship between the air blowing pressure when all the polyester resin particles attached to the outer surface are separated from the outer surface satisfies the relationship shown by the following formula (P). If the relationship shown by the following formula (P) (more preferably formula (P2), and even more preferably formula (P3)) is satisfied, the non-electrostatic adhesion force generated between the outer surface of the endless belt and the toner is further reduced, and even when uneven paper is used as the recording medium, the reduction in transferability and the occurrence of white spots in the image are suppressed.

[0032] Formula (P): Spray pressure P46 / Spray pressure P0 ≤ 1.5 Equation (P2): Spray pressure P46 / Spray pressure P0 ≤ 1.45 Equation (P3): Spray pressure P46 / Spray pressure P0 ≤ 1.40 In equations (P) to (P3), P0 is the weight of polyester resin particles under a load of 0 g / cm². 2 After adhesion, P46 indicates the air pressure at which all polyester resin particles attached to the outer surface are separated from the outer surface, and the polyester resin particles are subjected to a load of 46 g / cm². 2 After adhesion, this indicates the air pressure at which all polyester resin particles attached to the outer surface are separated from the outer surface.

[0033] In equations (P) to (P3), the lower limit of "spray pressure P46 / spray pressure P0" is ideally 1, but for example, it can be 1.1 or 1.2.

[0034] Here, the spraying pressure P0 and spraying pressure P46 are measured in accordance with the method for determining whether or not the non-electrostatic adhesion characteristics are satisfied. Specifically, the spraying pressure P0 is determined using the same method as the one used to determine whether or not the non-electrostatic adhesion characteristics are satisfied, by finding the spraying pressure at which all polyester resin particles are separated from the sample piece. Spray pressure P46 refers to spraying polyester resin particles at a pressure of 46 g / cm² from a height of 10 cm or less above the outer surface of the endless belt. 2The material was sprayed, and a load of 46 g / cm was applied to the outer surface of the endless belt. 2 Aside from the adhesion method, the spraying pressure at which all polyester resin particles separate from the sample piece is determined using the same method as the method used to determine whether or not the non-electrostatic adhesion characteristics are satisfied.

[0035] <Surface free energy> The surface free energy of the outer surface of the endless belt according to this embodiment is preferably 47 mN / m or less, more preferably 40 mN / m or less, and even more preferably 35 mN / m or less, from the viewpoint of improving transferability to uneven paper. The lower limit of the surface free energy is, for example, 10 mN / m or more, from the viewpoint of the cleanability of the belt.

[0036] Surface free energy is measured using a contact angle meter CAM-200 (manufactured by KSV Corporation) and calculated using the device's built-in program based on the Zisman method.

[0037] <Water contact angle> The water contact angle of the outer surface of the endless belt according to this embodiment is preferably 85° or higher, more preferably 90° or higher, and even more preferably 95° or higher, from the viewpoint of improving transferability to uneven paper. The lower limit of the water contact angle is, for example, 110° or lower, from the viewpoint of the cleanability of the belt.

[0038] The water contact angle is an indicator of water repellency and is measured as follows: Under conditions of 25°C and 50% humidity, 3 μl of pure water is dropped onto the surface of the object to be measured using a contact angle meter (Kyowa Interface Science Co., Ltd., model number: CA-X-FACE). The droplet is then photographed with an optical microscope 3 seconds after dropping. The water contact angle θ is then determined from the resulting image based on the θ / 2 method.

[0039] <Diiodomethane contact angle> The diiodomethane contact angle of the outer surface of the endless belt according to this embodiment is related to the transferability to uneven paper. From the above viewpoint, a contact angle of 40° or more is preferred, 45° or more is more preferred, and 50° or more and 50° or less is even more preferred. The lower limit of the diiodomethane contact angle is, for example, 80° or less from the viewpoint of belt cleanability.

[0040] The diiodomethane contact angle is an indicator of oil repellency and is measured as follows. Under conditions of 25°C and 50% humidity, 3 μl of diiodomethane (purity = 99%) is dropped onto the surface of the object to be measured using a contact angle meter (Kyowa Interface Science Co., Ltd., model number: CA-X-FACE). Three seconds after dropping, the droplet is photographed using an optical microscope. The diiodomethane contact angle θ is then determined from the obtained image based on the θ / 2 method.

[0041] <Layer configuration> The endless belt according to this embodiment has a layer containing a resin (hereinafter also referred to as the "first resin"), conductive particles (hereinafter also referred to as the "first conductive particles"), and a surfactant.

[0042] The endless belt may be a single layer or a laminate. In other words, the endless belt is a single layer consisting of a layer containing a first resin and first conductive particles, or a laminate having said layer as a surface layer constituting the outer circumferential surface of the endless belt. If the endless belt is a single layer, the single layer is a layer containing a first resin, first conductive particles, and a surfactant. If the endless belt is a laminate, the laminate includes, 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 also have other surface layers between the base layer and the surface layer. When the endless belt is a laminate having a base layer and a surface layer, the surface layer is a layer of a first resin and first conductive particles. Preferably, the surface layer contains a surfactant. On the other hand, the base layer is not particularly limited, and for example, a layer containing a second resin and second conductive particles is an example.

[0043] In the endless belt according to the first embodiment, when a voltage is applied to the surface layer of the laminate or the single layer, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9 kV or less, and other layers (for example, a layer in the laminate containing a second resin and second conductive particles) do not need to satisfy the electrostatic properties.

[0044] In the endless belt according to the second embodiment, the number-average primary particle diameter of the first conductive particles is 11 nm or less, and the number-average primary particle diameter of the second conductive particles does not need to satisfy this range.

[0045] Hereafter, the layers of the endless belt, which are single-layered structures, will also be referred to as "single layers." Furthermore, in the laminated endless belt, the surface layer containing the first resin and the first conductive particles is also called the "first layer," and the base layer containing the second resin and the second conductive particles is also called the "second layer."

[0046] <Resin> Examples of the first resin included in the single layer or the first layer include polyimide resin (PI resin), polyamide-imide resin (PAI resin), aromatic polyether ketone resin (e.g., aromatic polyether ether ketone resin), polyphenylene sulfide resin (PPS resin), polyetherimide resin (PEI resin), polyester resin, polyamide resin, and Examples include recarbonate resins. The first resin preferably contains at least one selected from the group consisting of polyimide resin, polyamideimide resin, aromatic polyether ether ketone resin, polyetherimide resin, and polyphenylene sulfide resin, and more preferably contains at least one selected from the group consisting of polyimide resin and polyamideimide resin, from the viewpoint of mechanical strength and dispersibility of the first conductive particles. Among these, polyimide resin is even more preferred from the viewpoint of mechanical strength. The first resin may consist of one type of resin, or it may be a mixture of two or more types of resins.

[0047] Specific and preferred examples of the second resin contained in the second layer are the same as the specific and preferred examples of the first resin. The second resin may consist of one type of resin or may be a mixture of two or more types of resins. Furthermore, if 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 it is preferable that they are of the same type (for example, both the first resin and the second resin are polyimide resins).

[0048] (Polyimide resin) Examples of polyimide resins include imidized polyamic acid (a precursor of polyimide resin), which is a polymer of tetracarboxylic dianhydride and a diamine compound. Examples of polyimide resins include resins having constituent units represented by the following general formula (I).

[0049] [ka]

[0050] In general formula (I), R 1 represents a tetravalent organic group, R 2 This represents a divalent organic group. R 1 Examples of tetravalent organic groups represented by include aromatic groups, aliphatic groups, cyclic aliphatic groups, groups combining aromatic and aliphatic groups, or groups in which these are substituted. Specific examples of tetravalent organic groups include residues of tetracarboxylic dianhydrides, which will be discussed later. R 2 Examples of divalent organic groups represented by include aromatic groups, aliphatic groups, cyclic aliphatic groups, groups combining aromatic and aliphatic groups, or groups in which these are substituted. Specific examples of divalent organic groups include residues of diamine compounds, which will be discussed later.

[0051] Specifically, the tetracarboxylic dianhydrides used as raw materials for polyimide resins include pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, and 1,4,5,8-naphthalene Examples include tetracarboxylic dianhydrides, 2,2'-bis(3,4-dicarboxyphenyl)sulfonic acid dianhydrides, perylene-3,4,9,10-tetracarboxylic dianhydrides, bis(3,4-dicarboxyphenyl) ether dianhydrides, and ethylenetetracarboxylic dianhydrides.

[0052] Specific examples of diamine compounds used as raw materials for polyimide resins 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'-biphenyldiamine, benzidine, and 3,3'-dimethyl Benzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylpropane, 2,4-bis(β-aminoteric)toluene, bis(p-β-aminoteric)butylphenyl)ether, bis(p-β-methyl-δ-aminophenyl)benzene, bis-p-(1,1-dimethyl-5-aminopentyl)benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di(p -Aminocyclohexyl)methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, Examples include 3-methylheptamethylenediamine, 5-methylnonameethylenediamine, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 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.

[0053] (Polyamide-imide resin) Examples of polyamide-imide resins include resins having imide bonds and amide bonds in their repeating units. More specifically, polyamide-imide resins include polymers of a trivalent carboxylic acid compound (also called tricarboxylic acid) having an acid anhydride group and a diisocyanate compound or diamine compound.

[0054] As the tricarboxylic acid, trimellitic anhydride and its derivatives are preferred. In addition to tricarboxylic acids, tetracarboxylic dianhydrides, aliphatic dicarboxylic acids, aromatic dicarboxylic acids, etc. may be used in combination.

[0055] Examples of diisocyanate compounds 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. Examples of diamine compounds include those having a structure similar to the isocyanates described above, but with an amino group instead of an isocyanate group.

[0056] (Aromatic polyether ketone resin) Examples of aromatic polyetherketone resins include resins in which aromatic rings, such as benzene rings, are linked in a linear fashion by ether and ketone bonds. Examples of aromatic polyetherketone resins include polyetherketones (PEK) in which ether bonds and ketone bonds are arranged alternately, polyetheretherketones (PEEK) in which ether bonds, ether bonds, and ketone bonds are arranged in that order, polyetherketoneketones (PEKK) in which ether bonds, ketone bonds, and ketone bonds are arranged in that order, polyetheretherketoneketones (PEEKK) in which ether bonds, ether bonds, ketone bonds, and ketone bonds are arranged in that order, and polyetherketone esters containing ester bonds.

[0057] The content of the first resin relative to the entire single 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 even more preferably 75% by mass or more and 90% by mass or less, from the viewpoint 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 even more preferably 75% by mass or more and 90% by mass or less, from the viewpoint 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 even more preferably 75% by mass or more and 90% by mass or less, from the viewpoint of adjusting mechanical strength and volume resistivity.

[0058] <Conductive particles> Examples of the first conductive particles included in the single layer or the first layer include at least one selected from the group consisting of conductive carbon particles and metal oxide particles. Among the above, the first conductive particle preferably includes conductive carbon particles. When the first conductive particles include conductive carbon particles, the resulting endless belt is expected to have superior non-electrostatic adhesion properties, and consequently, superior transferability to uneven paper. Examples of conductive carbon particles include carbon black. Examples of carbon black include Ketjen black, oil furnace black, channel black, and acetylene black. Surface-treated carbon black (hereinafter also referred to as "surface-treated carbon black") may also be used. Surface-treated carbon black is obtained by imparting, for example, carboxyl groups, quinone groups, lactone groups, hydroxyl groups, etc., to its surface. Examples of surface treatment methods include air oxidation, in which carbon black is reacted with air in a high-temperature atmosphere; a method of reacting carbon black with nitrogen oxides or ozone at room temperature (e.g., 22°C); and a method of air oxidation in a high-temperature atmosphere followed by oxidation with ozone at a low temperature.

[0059] Examples of metal oxide particles include tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles.

[0060] Examples of the first type of conductive particle include metal particles (e.g., aluminum particles, nickel particles, etc.) and ionic conductive particles (e.g., potassium titanate particles, LiCl particles, etc.).

[0061] In the first embodiment, the number-average primary particle diameter of the first conductive particles is preferably 11 nm or less, more preferably 6 nm to 10 nm, and even more preferably 8 nm to 10 nm, from the viewpoint of transferability to uneven paper. In the second embodiment, the number-average primary particle diameter of the first conductive particles is 11 nm or less, and from the viewpoint of transferability to uneven paper, it is preferably 6 nm to 10 nm, and more preferably 8 nm to 10 nm. When the number-average primary particle diameter of conductive particles is 11 nm or less, the electrostatic adhesion force on the surface layer is reduced. As a result, the electrostatic adhesion force generated between the outer surface of the endless belt and the toner is also reduced, which is thought to result in excellent transferability to uneven paper.

[0062] The number-average primary particle diameter of the second conductive particle can be in the range of 2 nm to 40 nm, and from the viewpoint of dispersibility, mechanical strength, volume resistivity, film formation properties, 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 even more preferred.

[0063] When the endless belt has a first layer and a second layer, it is preferable that the number-average primary particle diameter of the first conductive particles is smaller than the number-average primary particle diameter of the second conductive particles. The number-average primary particle diameter of the first conductive particles is preferably 0.3 times or more and less than 0.9 times the number-average primary particle diameter of the second conductive particles, more preferably 0.3 times or more and 0.7 times or less, and even more preferably 0.3 times or more and 0.5 times or less. When the relationship between the number-average primary particle diameters of the first conductive particles and the second conductive particles is within the above range, it is considered that both transferability to uneven paper and suppression of image defects (e.g., color loss) are superior.

[0064] The number-average primary particle diameter of conductive particles is measured by the following method. First, a 100 nm thick sample is taken from each layer of the obtained belt using a microtome, and this sample is observed using a TEM (transmission electron microscope). Then, the diameter of a circle equal to the projected area of ​​each of the 50 conductive particles (i.e., the equivalent circle diameter) is taken as the particle diameter, and the average value of these values ​​is taken as the number-average primary particle diameter.

[0065] The first resin comprises at least one selected from the group consisting of polyimide resins and polyamideimide resins, and when a single layer or a first layer is formed using the first coating liquid described later, the first conductive particles are preferably conductive carbon particles from the viewpoint of improving transferability to uneven paper.

[0066] The first conductive particle may be a single type or a mixture of two or more types. Specific examples of the second conductive particles contained in the second layer are similar to those of the first conductive particles.

[0067] The content of the second conductive particles in the entire second layer is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, and even more preferably 20% by mass or more and 30% by mass or less, from the viewpoint of dispersibility, mechanical strength, and volume resistivity adjustment.

[0068] The content of conductive particles in the layer containing the resin and conductive particles is preferably 10% to 30% by mass, more preferably 15% to 25% by mass, and even more preferably 18% to 23% by mass, relative to the total solid content of the layer. When the content of conductive particles in the layer is within the above range, the conductive particles tend to be highly dispersible within the layer, and the electrostatic adhesion in the layer tends to decrease. As a result, the electrostatic adhesion generated between the outer surface of the endless belt and the toner also decreases, and it is thought that the transferability to uneven paper is excellent.

[0069] <Surfactants> The layer containing the resin and conductive particles preferably further contains a surfactant. If the aforementioned layer further contains a surfactant, conductive particles with a small number-average primary particle diameter and surfactants that lower surface free energy become more easily dispersed within the layer. This reduces the non-electrostatic adhesion force generated between the outer surface of the endless belt and the toner. Therefore, even when using textured paper as the recording medium, it is thought that the reduction in transferability and the occurrence of white spots in the image are further suppressed.

[0070] Suitable surfactants include those having at least one of the following structures: perfluoroalkyl structure, alkylene oxide structure, and silicone structure. When surfactants having these structures are applied, the non-electrostatic adhesion properties, surface free energy, water contact angle, and diiodomethane contact angle are satisfied, and the transferability to uneven paper is easily improved.

[0071] Suitable surfactants having a perfluoroalkyl structure include perfluoroalkyl sulfonic acids (e.g., perfluorobutanesulfonic acid, perfluorooctanesulfonic acid, etc.), perfluoroalkyl carboxylic acids (e.g., perfluorobutanecarboxylic acid, perfluorooctanecarboxylic acid, etc.), and perfluoroalkyl group-containing phosphate esters. Perfluoroalkyl sulfonic acids and perfluoroalkyl carboxylic acids may also be their salts and amide modified forms.

[0072] Examples of commercially available surfactants having a perfluoroalkyl structure include the Megafac® series (manufactured by DIC Corporation), the F-Top series (manufactured by JEMCO Corporation), the Futergent series (manufactured by Neos Corporation), the Surflon® series (manufactured by AGC Seimi Chemical Co., Ltd.), the PF series (manufactured by Kitamura Chemical Co., Ltd.), and the FC series (manufactured by 3M Corporation).

[0073] Examples of surfactants having an alkylene oxide structure include polyethylene glycol, polyether defoamers, and polyether-modified silicone oils. Polyethylene glycol with a number-average molecular weight of 2000 or less is preferred. Examples of polyethylene glycols with a number-average molecular weight of 2000 or less include polyethylene glycol 2000 (number-average molecular weight 2000), polyethylene glycol 600 (number-average molecular weight 600), polyethylene glycol 400 (number-average molecular weight 400), and polyethylene glycol 200 (number-average molecular weight 200). Examples of polyether defoamers include the PE series (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and the defoamer series (manufactured by Kao Corporation). Examples of polyether-modified silicone oils include silicone oils in which at least one of the side chains and terminals of a polysiloxane chain is modified with a polyalkylene oxide.

[0074] Examples of surfactants having a silicone structure include common silicone oils such as dimethyl silicone, methylphenyl silicone, diphenyl silicone, and their derivatives. Examples of surfactants having a silicone structure include the KF series 351(A), KF352(A), KF353(A), KF354(A), KF355(A), KF615(A), KF618, KF945(A), KF6004, KP126, KP109 (all manufactured by Shin-Etsu Chemical Co., Ltd.), the TSF series (manufactured by GE Toshiba Silicon Corporation), the BYK series-UV series etc. (manufactured by BIC Chemie Japan Co., Ltd.), and the Ogusol series (manufactured by Osaka Gas Chemical Co., Ltd.).

[0075] Among these, the surfactant is preferably at least one of an oligomer having a perfluoroalkyl structure with 6 or fewer carbon atoms, and an oligomer having a silicone structure with a methyl group. Applying these surfactants satisfies the requirements for non-electrostatic adhesion, surface free energy, water contact angle, and diiodomethane contact angle, making it easier to improve transferability to textured paper.

[0076] Here, the oligomer having a perfluoroalkyl structure with 6 or fewer carbon atoms may be an oligomer having a substituent with a fluorine atom with 6 or fewer carbon atoms (preferably 2 to 6 carbon atoms). However, from the viewpoint of satisfying non-electrostatic adhesion properties, surface free energy, water contact angle, and diiodomethane contact angle, and improving transferability to uneven paper, an oligomer having a perfluoroalkyl structure with 6 or fewer carbon atoms (preferably 2 to 6 carbon atoms) is preferred.

[0077] Furthermore, oligomers having a silicone structure with a methyl group are preferred because they satisfy non-electrostatic adhesion properties, surface free energy, water contact angle, and diiodomethane contact angle, and improve transferability to uneven paper. Specifically, oligomers having at least one of the following silicone structures are preferred: "-SiH(CH3)-O-", "-Si(CH3)2-O-", and "-Si(CH3)(Ph)-O-" (where Ph represents a phenyl group in the structural formula). Furthermore, the surfactant may be an oligomer having a silane structure with a methyl group. Specifically, an oligomer having a silane structure with a methyl group is -[SiH(CH3)] n -Structure, -[Si(CH3)2] n - Structure, and -[Si(CH3)(Ph)] n -Oligomers having at least one of the following structures (in the structural formula, Ph represents a phenyl group and n represents an integer of 2 or more) are preferred.

[0078] From the viewpoint of satisfying non-electrostatic adhesion characteristics, surface free energy, water contact angle, and diiodomethane contact angle, and improving transferability to uneven paper, these oligomers are preferably polymers in which four or more monomers are bonded together. In other words, it is preferable that the number of repeating monomer units in the oligomer is four or more. The oligomer is preferably a polymer in which 4 to 1000 (or 4 to 300) monomers are bonded together. In other words, the number of repeating monomer units in the oligomer is preferably 4 to 1000 (or 4 to 300). In the case of oligomers, the monomer is a monomer having a perfluoroalkyl structure (e.g., (meth)acrylic acid ester, etc.) in the case of oligomers having a perfluoroalkyl structure with 6 or fewer carbon atoms, and a siloxane having a methyl group in the case of oligomers having a silicone structure with a methyl group.

[0079] The surfactant content is adjusted to a range that satisfies the non-electrostatic adhesion properties, surface free energy, water contact angle, and diiodomethane contact angle. The surfactant content is preferably 0.5% to 10% by mass, more preferably 0.7% to 7% by mass, and even more preferably 1.0% to 5% by mass, relative to the layer containing the surfactant.

[0080] When the layer containing the resin and conductive particles further contains a surfactant, the content of the interfacial lubricant is preferably 1% to 6% by mass, more preferably 1.5% to 5% by mass, and even more preferably 2% to 4% by mass, relative to the total solid content of the layer. When the surfactant content is within the above range, the electrostatic adhesion characteristics are superior, and as a result, the transferability to uneven paper is considered to be superior.

[0081] <Other ingredients> The single layer, the first layer, and the second layer may each contain other components in addition to the resin and conductive particles. Other components include, for example, conductive materials other than conductive particles, fillers to improve the strength of the belt, antioxidants to prevent thermal degradation of the belt, surfactants to improve fluidity, and heat-resistant anti-aging agents. If the above layer contains other components, the content of the other components is preferably greater than 0% by mass and 10% by mass or less, more preferably greater than 0% by mass and 5% by mass or less, and even more preferably greater than 0% by mass and 1% by mass or less, relative to the total mass of the layer in question.

[0082] <Characteristics of an endless belt> (Thickness of the endless belt) From the viewpoint of the mechanical strength of the belt, the thickness of the single layer is preferably 60 μm to 120 μm, and more preferably 80 μm to 120 μm. The thickness of the first layer is preferably 1 μm to 60 μm, and more preferably 3 μm to 60 μm, from the viewpoint of manufacturability and suppression of discharge. The thickness of the second layer is preferably 10 μm to 80 μm, and more preferably 20 μm to 40 μm, from the viewpoint of the mechanical strength of the belt. When the endless belt has a first layer and a second layer, from the viewpoint of transferability to uneven paper, the total thickness The proportion of the first layer to the total is preferably 3% to 90%, and more preferably 5% to 80%. The film thickness of each layer is measured as follows. Specifically, the 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 of these measurements is taken as the thickness.

[0083] (Potential decay rate of an endless belt) The potential decay rate dV / dt (hereinafter also simply referred to as "potential decay rate") after the outer surface of the endless belt has been charged to +500V is preferably 2.0V / msec or more and 6.0V / msec or less, more preferably 2.3V / msec or more and 5.2V / msec or less, and even more preferably 2.3V / msec or more and 3.8V / msec or less, from the viewpoint of transferability to uneven paper.

[0084] The reason why a potential decay rate of 2.0 V / msec to 6.0 V / msec in the endless belt improves transferability to textured paper is unclear, but it is speculated as follows. When an endless belt is used as an intermediate transfer body in a transfer device, for example, in the region where the toner image is transferred from the intermediate transfer body to the recording medium (hereinafter also referred to as the "secondary transfer region"), a transfer electric field is applied from the inner surface side of the intermediate transfer body. As the intermediate transfer body passes through this secondary transfer region, an electric charge is generated on the inner surface of the intermediate transfer body by the transfer electric field, and the generated charge moves within the intermediate transfer body to reach the outer surface of the intermediate transfer body. For example, in high-speed image forming machines where the transport speed of the recording medium passing through the secondary transfer region is 300 mm / s or more, if a large amount of charge reaches the outer surface of the intermediate transfer material while it is passing through the secondary transfer region, abnormal discharge is likely to occur. On the other hand, if too little charge reaches the outer surface of the intermediate transfer material while it is passing through the secondary transfer region, charge may flow from the toner into the intermediate transfer material, reducing the charge level of the toner and making transfer difficult. In contrast, if the potential decay rate of the endless belt is 2.0 V / msec or more and 6.0 V / msec or less, even when used as an intermediate transfer body in a high-speed machine's transfer device, the amount of charge reaching the outer surface of the intermediate transfer body while it passes through the secondary transfer region is appropriate, and the conductive points are finely dispersed on the outer surface of the intermediate transfer body. This suppresses abnormal discharge and a decrease in the toner charge, thereby improving transferability.

[0085] Here, the potential decay rate of the endless belt is calculated by attaching a 50mm x 60mm belt piece to an insulating board, placing a surface potential meter (for example, Trek Japan, model number: Model 314) on the belt surface (i.e., the outer surface), charging the belt piece to 500V using a Scorotron with an opening width of 18mm set to a grid voltage of 580V, and then measuring the surface potential of the belt immediately after charging and after decay every 10 msec.

[0086] The method for controlling the potential decay rate of an endless belt is not particularly limited and includes, for example, selecting the number-average primary particle size and type of conductive particles used, and adjusting the conditions in the manufacturing process of the endless belt (e.g., drying conditions). In particular, when the endless belt is a laminate, the potential decay rate can be controlled not only by adjusting the drying conditions of the surface layer and the base layer, but also by adjusting the combination of the drying conditions of the surface layer and the base layer. Furthermore, the recording medium transport speed (i.e., the transport speed of the recording medium passing through the secondary transfer region) of an image forming apparatus using an endless belt with a potential decay rate of 2.0 V / msec or more and 6.0 V / msec or less is preferably 50 mm / s or more and 600 mm / s or less, more preferably 100 mm / s or more and 600 mm / s or less, and even more preferably 300 mm / s or more and 600 mm / s or less.

[0087] (Volume resistivity of an endless belt) When a voltage of 500V is applied to an endless belt for 10 seconds, the common logarithm of the volume resistivity is preferably 9.0 (logΩ·cm) or more and 13.5 (logΩ·cm) or less, more preferably 9.5 (logΩ·cm) or more and 13.2 (logΩ·cm) or less, and particularly preferably 10.0 (logΩ·cm) or more and 12.5 (logΩ·cm) or less, from the viewpoint of transferability to uneven paper. The volume resistivity of an endless belt when a voltage of 500V is applied for 10 seconds is measured by the following method. For resistance measurement, a micro-ammeter (Advantest R8430A) will be used, and a UR probe (Mitsubishi Chemical Analytech Co., Ltd.) will be used as the probe. Volume resistivity (logΩ·cm) will be measured at 18 points in total: 6 points at equal intervals in the circumferential direction of the endless belt, and 3 points at the center and both ends in the width direction. The measurement will be taken at a voltage of 500V for 10 seconds and a pressure of 1kgf, and the average value will be calculated. The measurements will be performed in an environment with a temperature of 22°C and a humidity of 55%RH.

[0088] (Surface resistivity of an endless belt) When a voltage of 500V is applied to the outer surface of the endless belt for 10 seconds, the common logarithm of the surface resistivity is preferably 10.0 (logΩ / suq.) or more and 15.0 (logΩ / suq.) or less, more preferably 10.5 (logΩ / suq.) or more and 14.0 (logΩ / suq.) or less, and particularly preferably 11.0 (logΩ / suq.) or more and 13.5 (logΩ / suq.) or less, from the viewpoint of transferability to uneven paper. The unit logΩ / suq. for surface resistivity is also expressed as log(Ω / suq.), logΩ / suq., logΩ / square, logΩ / □, etc., as it represents the surface resistivity as the logarithm of the resistance value per unit area. The surface resistivity of the endless belt when a voltage of 500V is applied to its outer surface for 10 seconds is measured by the following method. A micro-ammeter (Advantest R8430A) will be used as the resistance measuring instrument, and a UR probe (Mitsubishi Chemical Analytec Co., Ltd.) will be used as the probe. The surface resistivity (logΩ / suq.) of the outer surface of the endless belt will be measured at a total of 18 points: 6 points at equal intervals in the circumferential direction and 3 points at the center and both ends in the width direction. The measurement will be performed at a voltage of 500V for 10 seconds and a pressure of 1kgf, and the average value will be calculated. The measurements will be performed in an environment with a temperature of 22°C and a humidity of 55%RH.

[0089] <Manufacturing method for endless belts> The method for manufacturing an endless belt according to this embodiment is not particularly limited. One example of a method for manufacturing an endless belt includes, for example, a first coating solution preparation step of preparing a first coating solution containing a first resin or its precursor, first conductive particles, and a first solvent; a first coating film formation step of applying the first coating solution to the outer circumference 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 solution preparation step, the first coating film formation step, and the first drying step, the above method for manufacturing an endless belt may also include other steps. Other steps include, for example, a first firing step of firing the first coating film dried in the first drying step when a precursor of the first resin is used.

[0090] When manufacturing an endless belt that is a single layer, a single layer containing the first resin and the first conductive particles is formed on the outer surface of the material to be coated by going through the first coating solution preparation step, the first coating film formation step, and the first drying step described above. The single layer may be formed, for example, by creating pellets containing the first resin and the first conductive particles and melt-extruding these pellets.

[0091] When manufacturing an endless belt which is a laminate, for example, by going through the first coating solution preparation step, the first coating film formation step, and the first drying step, a first layer containing a first resin and first conductive particles is formed on the outer surface of the second layer formed on the material to be coated. When manufacturing an endless belt which is a laminate, the second layer is formed on the outer surface of the material to be coated by, for example, a second coating solution preparation step of preparing a second coating solution containing a second resin or its precursor, second conductive particles, and a second solvent; a second coating film formation step of applying the second coating solution to the outer surface of the material to be coated to form a second coating film; and a second drying step of drying the second coating film. The second layer may also be formed by, for example, creating pellets containing the second resin and second conductive particles and melt-extruding these pellets.

[0092] (Coating solution preparation process) In the first coating solution preparation step, a first coating solution containing a first resin or its precursor, first conductive particles, and a first solvent is prepared. For example, if the first resin is a polyimide resin and the first conductive particles are carbon black, the first coating solution is prepared in which, for example, carbon black is dispersed and polyamic acid, which is a precursor of the polyimide resin, is dissolved in the first solvent. Alternatively, if the first resin is a polyamide-imide resin and the first conductive particles are carbon black, the first coating solution is prepared in which, for example, carbon black is dispersed and polyamide-imide resin is dissolved in the first solvent.

[0093] As a method for preparing the first coating solution, it is preferable to perform a dispersion treatment using a pulverizer such as a ball mill or jet mill, from the viewpoint of pulverizing aggregates of the first conductive particles and from the viewpoint of improving the dispersibility of the first conductive particles. The first solvent is not particularly limited and can be appropriately determined depending on the type of resin used as the first resin. For example, when the first resin is a polyimide resin or a polyamide-imide resin, a polar solvent described later is preferably used as the first solvent.

[0094] 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), hexamethylene phosphoramide (HMPA), N-methyl caprolactam, N-acetyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone (N,N-dimethylimidazolidinone, DMI). These can be used individually or in combination of two or more.

[0095] If the process involves a second coating solution preparation step, a second coating solution containing a second resin, second conductive particles, and a second solvent is prepared in the second coating solution preparation step. The second resin and second conductive particles are as described above, and the method for preparing the second coating solution and the second solvent are the same as those for preparing the first coating solution and the first solvent, respectively.

[0096] (Coating film formation process) In the first coating film formation step, the first coating liquid is applied to the outer surface of the material to be coated to form the first coating film. Examples of materials to be coated include cylindrical or columnar molds. The material to be coated may be a mold whose outer surface has been treated with a release agent. When manufacturing an endless belt that is a single layer, in the first coating film formation step, for example, the first coating liquid is applied directly to the outer surface of the material to be coated or the material to be coated that has been treated with a release agent. When manufacturing an endless belt that is a laminate, in the first coating film formation step, for example, the first coating liquid is applied to the outer surface of the material to be coated on which the second layer or the second coating film has been formed.

[0097] Examples of known methods for applying the first coating solution include spray coating, spiral coating (flow coating), blade coating, wire bar coating, immersion coating, bead coating, air knife coating, and curtain coating. Furthermore, if a second coating film formation step is performed, in the second coating film formation step, the second coating solution is applied to the outer surface of the material to be coated to form the second coating film. The method of applying the second coating solution is the same as the method of applying the first coating solution.

[0098] (drying process) In the first drying step, the first coating film formed in the first coating film formation step is dried. The first drying step removes the first solvent contained in the first coating film, and a single layer or a first layer is obtained. Methods for drying the first coating film include, for example, supplying hot air to the first coating film or heating the material to be coated.

[0099] In the first drying step, when A°C is the integral mean value of the temperature of the material to be coated during the drying step, and Bmin is the time from the start of drying until the temperature of the material to be coated reaches the integral mean value A°C, it is preferable that the integral mean heating rate A / B (°C / min) is 5.74°C / min or higher. By having the above integral mean heating rate A / B (°C / min) of 5.74°C / min or higher, an endless belt with excellent transferability to uneven paper when used as an intermediate transfer material can be obtained. The reason for this is not clear, but it is presumed to be as follows. Specifically, if the integral mean heating rate A / B is large, the first coating film dries quickly, and the first conductive particles are fixed within the first coating film before aggregation occurs, resulting in a layer in which the first conductive particles are well dispersed. Furthermore, it is presumed that the fine dispersion of the first conductive particles within the resulting layer results in an endless belt with excellent transferability to uneven paper when used as an intermediate transfer material.

[0100] Here, the integral mean heating rate A / B is calculated by first measuring the time change in the temperature of the material to be coated during the drying process by connecting a thermometer (for example, a Graphtec K-type thermocouple, model number: JBS-7115-5M-K) to a Graphtec data recorder (model number: GL240). Then, the temperature at which the integrated value (area) of the temperature of the material to be coated from the start of drying becomes half of the integrated value (area) of the temperature of the material to be coated from the start of drying to the end of drying is defined as the "integral mean value (A°C)". The time (Bmin) from the start of drying until the temperature of the material to be coated reaches the integral mean value A°C is determined, and the integral mean heating rate A / B (°C / min) is calculated.

[0101] The integral mean heating rate A / B (°C / min) is more preferably 5.74°C / min or higher, and even more preferably 8.0°C / min or higher. The method for controlling the integral mean heating rate A / B within the above range is not particularly limited. For example, when drying the first coating film by supplying hot air to the surface of the first coating film, methods include adjusting the velocity of the hot air on the surface of the first coating film and adjusting the temperature of the hot air.

[0102] The velocity of the hot air on the surface of the first coated film is, for example, 0.1 m / s or more and 50 m / s or more. The following ranges are possible, with a range of 1 m / s to 40 m / s being preferred, and a range of 1 m / s to 20 m / s being more preferred. Here, the velocity of the hot air on the surface of the first coating film is measured as follows. Specifically, an anemometer (TM350, manufactured by TASCO) is used, with the probe placed on the surface of the coating film for measurement.

[0103] The temperature of the hot air on the surface of the first coated film can be, 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. The temperature of the hot air on the surface of the first coated film is measured by a thermometer (for example, a Graphtec K-type thermocouple, model number: JBS-7115-5M-K) connected to a Graphtec data recorder, model number: GL240). The method for supplying hot air to the surface of the first coating film is not particularly limited, and examples include blowing hot air from a drying oven towards the surface of the first coating film through a slit nozzle, or supplying hot air from a drying oven directly to the first coating film. Among these, the method using a slit nozzle is preferred from the viewpoint of making it easier to control the velocity of the hot air on the surface of the first coating film.

[0104] If a second drying step is performed, the second coating film formed in the second coating film formation 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 formation step is performed, or the first coating film formation step may be performed before the second drying step is completed, with the first drying step also serving as part of the second drying step.

[0105] (Firing process) As described above, the method for manufacturing the endless belt may also include a first firing step. In the first firing step, the first coating film, which has been dried in the first drying step, is fired by heating. For example, if the first resin is a polyimide resin, the polyamic acid contained in the first coating film is imidized in the first firing step, and polyimide is obtained. The heating temperature in the first firing step can be, for example, in the range of 150°C to 450°C, and preferably in the range of 200°C to 430°C. The heating time in the first firing step can be, for example, in the range of 20 minutes to 180 minutes, and preferably in the range of 60 minutes to 150 minutes. Furthermore, when manufacturing an endless belt which is a laminate, if the second layer is formed by a second coating solution preparation step, a second coating film formation step, and a second drying step, a second firing step may be performed to fire the second coating film that has been dried by the second drying step. The second firing step may also serve as the first firing step.

[0106] [Transfer device] The transfer apparatus according to this embodiment comprises an intermediate transfer body on which a toner image is transferred to its outer circumferential surface, a primary transfer apparatus having a primary transfer member that primary transfers a toner image formed on the surface of an image holder to the outer circumferential surface of the intermediate transfer body, and a secondary transfer apparatus having a secondary transfer member that is positioned in contact with the outer circumferential surface of the intermediate transfer body and secondary transfers the toner image transferred to the outer circumferential surface of the intermediate transfer body to the surface of a recording medium. The endless belt according to this embodiment is used as the intermediate transfer body.

[0107] In the primary transfer device, the primary transfer member is positioned opposite the image holder, with the intermediate transfer body in between. In the primary transfer device, the primary transfer member applies a voltage with the opposite polarity to the charge polarity of the toner to the intermediate transfer body, thereby primary transferring the toner image to the outer surface of the intermediate transfer body.

[0108] In the secondary transfer apparatus, the secondary transfer member is positioned on the toner image holding side of the intermediate transfer body. The secondary transfer apparatus also includes, for example, a back member positioned on the opposite side of the intermediate transfer body from the toner image holding side, together with the secondary transfer member. In the secondary transfer apparatus, the toner image on the intermediate transfer body is transferred to the recording medium by sandwiching the intermediate transfer body and the recording medium between the secondary transfer member and the back member to form a transfer field. The secondary transfer member may be a secondary transfer roll or a secondary transfer belt. For example, a backing roll may be used as the backing member.

[0109] Furthermore, the transfer apparatus according to this embodiment may be a transfer apparatus that transfers a toner image to the surface of a recording medium via a plurality of intermediate transfer bodies. In other words, the transfer apparatus may be, for example, a transfer apparatus that first transfers the toner image from an image holder to a first intermediate transfer body, then secondarily transfers the toner image from the first intermediate transfer body to a second intermediate transfer body, and finally tertiarily transfers the toner image from the second intermediate transfer body to the recording medium. If the transfer device includes a plurality of intermediate transfer bodies, at least the endless belt according to this embodiment is applied to the intermediate transfer body that transfers the toner image to the recording medium.

[0110] In image forming apparatuses, increasing the image formation speed requires increasing the transport speed of the recording medium. Consequently, in transfer apparatuses, from the perspective of ensuring transferability, it is necessary to apply a large electric field during secondary transfer and to widen the contact width (also called the nip width) between the intermediate transfer body and the secondary transfer member. On the other hand, widening the contact width between the intermediate transfer body and the secondary transfer member increases the probability of exposure to abnormal discharge and also increases the non-electrostatic adhesion force between the outer surface of the intermediate transfer body and the toner image. Therefore, especially when using textured paper as the recording medium, the transferability may actually decrease.

[0111] However, in the transfer apparatus according to this embodiment, since the endless belt according to this embodiment is provided as an intermediate transfer body, even when a large electric field is applied for secondary transfer, abnormal discharge is less likely to occur, and a decrease in transferability to uneven paper is suppressed.

[0112] Furthermore, the endless belt according to this embodiment, used as an intermediate transfer body, has low non-electrostatic adhesion between the outer surface of the intermediate transfer body and the toner image, thus improving transferability to uneven paper. Specifically, for example, even if the contact width between the intermediate transfer body and the secondary transfer member is widened to 0.2 cm or more and 4.0 cm or less (preferably 0.2 cm or more and 3.0 cm or less, more preferably 0.2 cm or more and 2.8 cm or less, and even more preferably 0.4 cm or more and 3.0 cm or less), the decrease in transferability to uneven paper is suppressed. More specifically, when the secondary transfer member is a secondary transfer roll, even if the contact width between the intermediate transfer body and the secondary transfer roll is widened to 0.2 cm or more and 4.0 cm or less (preferably 0.2 cm or more and 3.0 cm or less, more preferably 0.2 cm or more and 2.8 cm or less, and even more preferably 0.4 cm or more and 3.0 cm or less), the decrease in transferability to uneven paper is suppressed. Furthermore, when the secondary transfer member is a secondary transfer belt, even if the contact width between the intermediate transfer body and the secondary transfer belt is widened to 0.2 cm or more and 4.0 cm or less (preferably 0.2 cm or more and 3.0 cm or less, more preferably 0.2 cm or more and 2.8 cm or less, and even more preferably 0.4 cm or more and 3.0 cm or less), the decrease in transferability to uneven paper is suppressed. The contact width is the length of the portion where the intermediate transfer material and the secondary transfer member are in contact, and it is the length along the circumferential direction of the intermediate transfer material.

[0113] [Image forming apparatus] The image forming apparatus according to this embodiment comprises a toner image forming apparatus for forming a toner image on the surface of an image holder, and a transfer apparatus for transferring the toner image formed on the surface of the image holder to the surface of a recording medium. The transfer apparatus according to this embodiment is applied.

[0114] An example of a toner image forming apparatus is one comprising: an image holder; a charging device for charging the surface of the image holder; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the image holder; and a developing device for developing the electrostatic latent image formed on the surface of the image holder with a developer containing toner to form a toner image.

[0115] The image forming apparatus according to this embodiment includes a fixing means for fixing a toner image transferred to the surface of a recording medium; a cleaning means for cleaning the surface of an image holder before charging after the transfer of the toner image; a static elimination means for irradiating the surface of an image holder with static elimination light to eliminate static charge after the transfer of the toner image before charging; and a well-known image forming apparatus including an image holder heating member for raising the temperature of the image holder and reducing the relative temperature.

[0116] The image forming apparatus according to this embodiment may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing method using a liquid developer).

[0117] In the image forming apparatus according to this embodiment, for example, the part comprising the image holder may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising a toner image forming apparatus and a transfer apparatus is preferably used.

[0118] Hereinafter, an example of an image forming apparatus according to this embodiment will be described with reference to the drawings. However, the image forming apparatus according to this embodiment is not limited to this example. The main parts shown in the drawings will be described, and other parts will be omitted from the description.

[0119] (Image forming apparatus) Figure 1 is a schematic diagram showing the configuration of the image forming apparatus according to this embodiment.

[0120] As shown in Figure 1, the image forming apparatus 100 according to this embodiment is, for example, an intermediate transfer type image forming apparatus generally called a tandem type, and comprises a plurality of image forming units 1Y, 1M, 1C, 1K (an example of a toner image forming apparatus) in which toner images of each color component are formed by an electrophotographic method; a primary transfer unit 10 that sequentially transfers (primary transfer) the toner images of each color component formed by each image forming unit 1Y, 1M, 1C, 1K to an intermediate transfer belt 15; a secondary transfer unit 20 that transfers (secondary transfer) the superimposed toner images transferred on the intermediate transfer belt 15 to a recording medium, paper K, in one go; and a fixing device 60 that fixes the secondary transferred image onto the paper K. The image forming apparatus 100 also has a control unit 40 that controls the operation of each device (each part).

[0121] Each image forming unit 1Y, 1M, 1C, 1K of the image forming apparatus 100 is equipped with a photoreceptor 11 (an example of an image holder) that rotates in the direction of arrow A and holds the toner image formed on its surface.

[0122] Around the photoreceptor 11, a charger 12 is provided as an example of a charging means for charging the photoreceptor 11, and a laser exposure unit 13 (indicated by the symbol Bm in the figure) is provided as an example of a latent image forming means for writing an electrostatic latent image onto the photoreceptor 11.

[0123] Furthermore, surrounding the photoreceptor 11, as an example of a developing means, is a developer 14 which contains toners for each color component and visualizes the electrostatic latent image on the photoreceptor 11 using the toner, and a primary transfer roll 16 which transfers the toner images for each color component formed on the photoreceptor 11 to an intermediate transfer belt 15 in a primary transfer unit 10.

[0124] Furthermore, a photoreceptor cleaner 17 is provided around the photoreceptor 11 to remove any residual toner on the photoreceptor 11, and the electrophotographic devices, including the charger 12, laser exposure unit 13, developer unit 14, primary transfer roll 16, and photoreceptor cleaner 17, are sequentially arranged along the rotational direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially straight line from the upstream side of the intermediate transfer belt 15 in the order of yellow (Y), magenta (M), cyan (C), and black (K).

[0125] The intermediate transfer belt 15 is driven (rotated) in a circulating manner at a speed appropriate to the purpose in direction B shown in Figure 1 by various rolls. These various rolls include a drive roll 31 that rotates the intermediate transfer belt 15 by a motor (not shown) with excellent constant-speed performance, a support roll 32 that supports the intermediate transfer belt 15 which extends substantially linearly along the arrangement direction of each photoreceptor 11, a tension-applying roll 33 that applies tension to the intermediate transfer belt 15 and functions as a correction roll to prevent the intermediate transfer belt 15 from meandering, a back roll 25 provided in the secondary transfer section 20, and a cleaning back roll 34 provided in the cleaning section that scrapes off residual toner on the intermediate transfer belt 15.

[0126] The primary transfer section 10 consists of a primary transfer roll 16 positioned opposite the photoreceptor 11, with the intermediate transfer belt 15 in between. The primary transfer roll 16 is pressed against the photoreceptor 11 with the intermediate transfer belt 15 in between, and a voltage (primary transfer bias) with the opposite polarity to the charge polarity of the toner (negative polarity; the same applies hereinafter) is applied to the primary transfer roll 16. As a result, the toner images on each photoreceptor 11 are sequentially electrostatically attracted to the intermediate transfer belt 15, and superimposed toner images are formed on the intermediate transfer belt 15.

[0127] The secondary transfer section 20 comprises a back roll 25 and a secondary transfer roll 22 positioned on the toner image holding surface side of the intermediate transfer belt 15.

[0128] Back roll 25 has a surface resistivity of 1 × 10 7 Ω / □ or more 1×10 10 It is formed to be less than or equal to Ω / □, and its hardness is set to, for example, 70° (Asker C: manufactured by Polymer Instruments, the same applies hereafter). This back roll 25 is positioned on the back side of the intermediate transfer belt 15 and constitutes the opposing electrode of the secondary transfer roll 22, and is in contact with a metal power supply roll 26 to which the secondary transfer bias is stably applied.

[0129] On the other hand, the secondary transfer roll 22 has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 It is a cylindrical roll with a diameter of Ωcm or less. The secondary transfer roll 22 is pressed against the back roll 25 with the intermediate transfer belt 15 in between, and the secondary transfer roll 22 is grounded to form a secondary transfer bias between it and the back roll 25, thereby secondary transferring the toner image onto the paper K that is transported to the secondary transfer section 20.

[0130] Furthermore, an intermediate transfer belt cleaning member 35 is provided downstream of the secondary transfer section 20 of the intermediate transfer belt 15, which can be moved toward and away from the intermediate transfer belt 15 to remove residual toner and paper dust on the intermediate transfer belt 15 after secondary transfer and to clean the outer surface of the intermediate transfer belt 15. Furthermore, a secondary transfer roll cleaning member 22A is provided downstream of the secondary transfer section 20 of the secondary transfer roll 22 to remove residual toner and paper dust from the secondary transfer roll 22 after secondary transfer and to clean the outer surface of the intermediate transfer belt 15. The secondary transfer roll cleaning member 22A is exemplified by a cleaning blade. However, it may also be a cleaning roll.

[0131] The intermediate transfer belt 15, primary transfer roll 16, and secondary transfer roll 22 are examples of a transfer device. Here, the image forming apparatus 100 may be configured to include a secondary transfer belt (an example of a secondary transfer member) instead of the secondary transfer roll 22. Specifically, as shown in Figure 2, the image forming apparatus 100 may include a secondary transfer device comprising a secondary transfer belt 23, a drive roll 23A positioned opposite the back roll 25 via the intermediate transfer belt 15 and the secondary transfer belt 23, and an idler roll 23B that tensions the secondary transfer belt 23 together with the drive roll 23A.

[0132] On the other hand, upstream of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 is provided that generates a reference signal which serves as a reference for determining the image forming timing in each image forming unit 1Y, 1M, 1C, and 1K. Downstream of the black image forming unit 1K, an image density sensor 43 is provided for adjusting image quality. This reference sensor 42 recognizes a mark provided on the back of the intermediate transfer belt 15 and generates a reference signal. Based on the recognition of this reference signal, each image forming unit 1Y, 1M, 1C, and 1K is configured to start image forming according to instructions from the control unit 40.

[0133] Furthermore, the image forming apparatus according to this embodiment includes, as a means for transporting paper K, a paper storage section 50 for storing paper K, a paper feed roll 51 for taking out and transporting paper K accumulated in the paper storage section 50 at a predetermined timing, a transport roll 52 for transporting paper K fed out by the paper feed roll 51, a transport guide 53 for sending paper K transported by the transport roll 52 to the secondary transfer section 20, a transport belt 55 for transporting paper K that has been secondarily transferred by the secondary transfer roll 22 to the fixing device 60, and a fixing inlet guide 56 for guiding paper K to the fixing device 60.

[0134] Next, the basic image formation process of the image forming apparatus according to this embodiment will be described. In the image forming apparatus according to this embodiment, image data output from an image reading device (not shown) or a personal computer (PC) (not shown) is processed by an image processing device (not shown), and then image formation is performed by image forming units 1Y, 1M, 1C, and 1K.

[0135] The image processing device applies various image processing steps to the input reflectance data, including shading correction, positional shift correction, brightness / color space conversion, gamma correction, frame removal, color editing, and movement editing. The processed image data is converted into four-color chromatic data (Y, M, C, K) and output to the laser exposure unit 13.

[0136] In the laser exposure unit 13, according to the input color tone data, an exposure beam Bm emitted from, for example, a semiconductor laser is irradiated onto each of the photoreceptors 11 of the image forming units 1Y, 1M, 1C, and 1K. After the surface of each photoreceptor 11 of the image forming units 1Y, 1M, 1C, and 1K is charged by the charger 12, the surface is scanned and exposed by the laser exposure unit 13, and an electrostatic latent image is formed. The formed electrostatic latent image is then developed as toner images of the respective colors Y, M, C, and K by the respective image forming units 1Y, 1M, 1C, and 1K.

[0137] 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 in the primary transfer section 10, where each photoreceptor 11 comes into contact with the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a primary transfer roll 16 applies a voltage (primary transfer bias) with the opposite polarity to the toner's charge polarity (negative polarity) to the substrate of the intermediate transfer belt 15, and the toner images are sequentially superimposed on the outer surface of the intermediate transfer belt 15 to perform primary transfer.

[0138] After the toner image is sequentially transferred to the outer surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is transported to the secondary transfer section 20. When the toner image is transported to the secondary transfer section 20, the transport mechanism rotates the paper feed roll 51 in time with the transport of the toner image to the secondary transfer section 20, and paper K of the desired size is supplied from the paper storage section 50. The paper K supplied by the paper feed roll 51 is transported by the transport roll 52 and reaches the secondary transfer section 20 via the transport guide 53. Before reaching the secondary transfer section 20, the paper K is temporarily stopped, and the position of the paper K and the position of the toner image are aligned by rotating the alignment roll (not shown) in time with the movement of the intermediate transfer belt 15 holding the toner image.

[0139] In the secondary transfer section 20, the secondary transfer roll 22 is pressed against the back roll 25 via the intermediate transfer belt 15. At this time, the paper K, which has been transported in sync with the timing, is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. When a voltage (secondary transfer bias) with the same polarity as the charge polarity (negative polarity) of the toner is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the back roll 25. Then, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred all at once onto the paper K in the secondary transfer section 20, which is pressed by the secondary transfer roll 22 and the back roll 25.

[0140] Subsequently, the paper K on which the toner image has been electrostatically transferred is peeled off the intermediate transfer belt 15 by the secondary transfer roll 22 and transported to the transport belt 55 located downstream of the secondary transfer roll 22 in the paper transport direction. The transport belt 55 transports the paper K to the fuser 60 at an optimal transport speed for the fuser 60. The unfixed toner image on the paper K transported to the fuser 60 is fixed to the paper K by the fuser 60 through a fixing process using heat and pressure. The paper K with the fixed image then transported to the paper discharge and storage section (not shown) located in the discharge section of the image forming apparatus.

[0141] Meanwhile, after the transfer to paper K is completed, any residual toner remaining on the intermediate transfer belt 15 is transported to the cleaning section as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the cleaning back roll 34 and the intermediate transfer belt cleaner 35.

[0142] Although this embodiment has been described above, it is not intended to be interpreted as being limited to the above embodiment, and various modifications, changes, and improvements are possible. [Examples]

[0143] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. In the following description, unless otherwise specified, "parts" and "%" all refer to mass.

[0144] [Example A1] <Synthesis of polyamic acids> Polyamic acid DA-A1, in which both ends of the molecular chain are amino groups, and polyamic acid DC-A1, in which both ends of the molecular chain are carboxyl groups, were synthesized by the following method.

[0145] -Preparation of polyamic acid solution DA-A1- 800 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as "NMP") was mixed with 83.48 g (416.9 mmol) of 4,4'-diaminodiphenyl ether (hereinafter abbreviated as "ODA") as a diamine compound, and dissolved while stirring at room temperature (25°C). Next, 116.52 g (396.0 mmol) of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (hereinafter abbreviated as "BPDA") was gradually added as the tetracarboxylic acid dianhydride. After the addition and dissolution of the tetracarboxylic acid dianhydride, the reaction solution was heated to 60°C, and then the polymerization reaction was carried out for 20 hours while maintaining the reaction solution temperature to obtain a reaction solution containing polyamic acid DA-A1 and NMP.

[0146] The resulting reaction solution was filtered using an #800 stainless steel mesh and cooled to room temperature (25°C) to obtain polyamic acid solution DA-A1 with a solution viscosity of 2.0 Pa·s at 25°C. The viscosity of the polyamic acid solution was measured using a Toki Sangyo Co., Ltd. E-type rotational viscometer, model TV-20H, with a standard rotor (1°34“×R24), at a measurement temperature of 25°C and rotational speeds of 0.5 rpm (100 Pa·s or more) and 1 rpm (less than 100 Pa·s). The solution viscosity of the polyamic acid solution obtained in the following synthesis examples was measured in the same manner.

[0147] -Preparation of polyamic acid solution DC-A1- Except for using 79.57 g (397.4 mmol) of ODA and 120.43 g (409.3 mmol) of BPDA, a polyamic acid solution DC-A1 containing polyamic acid DC-A1 and NMP with a solution viscosity of 6.0 Pa·s was obtained in the same manner as in Synthesis Example 1.

[0148] <Preparation of coating solution> -Preparation of coating solution A1 (second coating solution)- • Polyamic acid solution DA-A1 (solid content concentration: 45% by mass) 70 parts by mass • Polyamic acid solution DC-A1 (solid content concentration: 15% by mass) 30 parts by mass • Carbon black [dry state, second conductive particles, SPECIAL BLACK4, manufactured by Orion Engineered Carbons, 18.0% volatile content, gas black (i.e., channel black), number-average primary particle size: 25 nm (hereinafter also abbreviated as "SB-4")] 26 parts by mass The polyamic acid solutions DA-A1 and DC-A1, having the above compositions, were mixed, SB-4 was added, and the mixture was dispersed in a ball mill at 30°C for 12 hours. The mixture containing the dispersed SB-4 was then filtered through a #400 stainless steel mesh to obtain a second coating solution, coating solution A1.

[0149] -Preparation of coating solution B1 (first coating solution)- • Polyamic acid solution DA-A1 (solid content concentration: 45% by mass) 70 parts by mass • Polyamic acid solution DC-A1 (solid content concentration: 15% by mass) 30 parts by mass • Carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number-average primary particle size: 9 nm] 18 parts by mass • Surfactant (Surflon® S-651): The amount shown in Table 1-1 (the amount relative to the layer containing the surfactant (the same applies hereinafter)). Polyamic acid solutions DA-A1 and DC-A1 with the above compositions were mixed, and a surfactant was added along with Emperor2000. The mixture was dispersed in a polyamic acid solution by dispersing it in a ball mill at 30°C for 12 hours. Subsequently, the mixture containing dispersed Emperor2000 was filtered through an #800 stainless steel mesh to obtain coating solution B1, which was the first coating solution.

[0150] Note that the carbon black mentioned above [Emperor2000, manufactured by Cabot] is a basic carbon black.

[0151] <Making Belt A1> -Release agent treatment for the material to be coated- A cylindrical mold made of SUS material with an outer diameter of 366 mm and a length of 400 mm was prepared as the material to be coated. A silicone-based release agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name: Sepacoat SP) was applied to its outer surface, and a drying treatment (release agent treatment) was performed.

[0152] -Formation of the second coating film- A cylindrical mold treated with a release agent was rotated circumferentially at a speed of 10 rpm. The coating liquid A1 was dispensed from a 1.0 mm diameter dispenser from the end of the cylindrical mold and applied by pressing it with uniform pressure using a metal blade installed on the mold. By moving the dispenser unit in the axial direction of the cylindrical mold at a speed of 100 mm / min, the coating liquid A1 was applied in a spiral pattern on the cylindrical mold, forming a second coating film.

[0153] -Drying of the second coating- Subsequently, the mold and the second coating film were dried in a drying oven at 140°C in an air atmosphere for 15 minutes while rotating at 10 rpm. After drying, the solvent evaporates from the second coating film, transforming it into a self-supporting polyamic acid resin molded product (substrate 1).

[0154] -Formation and drying of the first coating film- After applying coating solution B1 to the outer surface of substrate 1 using the same rotary coating method as for coating solution A1 to form a first coating film, the first coating film was dried in a drying oven at 140°C in an air atmosphere while rotating at 10 rpm for 15 minutes. The integral mean heating rate A / B during the drying process of the first coating film was 6.00°C / min.

[0155] -Firing- Next, the endless belt A1 was obtained by placing it in an oven set to a temperature of 320°C for 4 hours. The total film thickness of the endless belt A1 (total film thickness of the base layer and surface layer) was 80 μm, of which the film thickness of the base layer was 26.7 μm and the film thickness of the surface layer was 53.3 μm. Remove the endless belt A1 from the mold, stretch the removed endless belt A1 over the holder, and insert The material was cut using a cutter with an adjusted angle to obtain an annular shape with a diameter of 366 mm and a width of 369 mm. This endless belt was designated as belt A1. Furthermore, the content of conductive carbon particles in the entire base layer of belt A1 is 22% by mass, and the content of conductive carbon particles in the total solid content of the surface layer is 18% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt A1 were measured using the method described above, the common logarithm of the volume resistivity was 11.5 (logΩ·cm), and the common logarithm of the surface resistivity was 11.5 (logΩ / suq.).

[0156] [Example A2] <Making Belt A2> Endless belt A2 was obtained in the same manner as endless belt A1, except that in the drying process of the first coating film, instead of drying in an air atmosphere at 140°C for 15 minutes, drying was performed in an air atmosphere at 170°C for 20 minutes. The total film thickness of endless belt A2 (total film thickness of the base layer and surface layer) was 80 μm, of which the film thickness of the base layer was 26.7 μm and the film thickness of the surface layer was 53.3 μm. The integral mean heating rate A / B in the drying process of the first coating film was 6.5°C / min.

[0157] Furthermore, endless belt A2 was cut in the same manner as endless belt A1 to obtain an annular body with a diameter of 366 mm and a width of 369 mm. The endless belt thus produced was designated as belt A2. Furthermore, the content of conductive carbon particles in the entire base layer of belt A2 is 22% by mass, and the content of conductive carbon particles in the total solid content of the surface layer is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt A2 were measured using the method described above, the common logarithm of the volume resistivity was 11.8 (logΩ·cm), and the common logarithm of the surface resistivity was 12.0 (logΩ / suq.).

[0158] [Example A3] <Making Belt A3> Endless belt A3 was obtained in the same manner as endless belt A1, except that in the drying process of the first coating film, the drying process was performed in a 115°C air atmosphere for 15 minutes instead of a 140°C air atmosphere for 15 minutes. The total film thickness of endless belt A3 (total film thickness of the base layer and surface layer) was 80 μm, of which the film thickness of the base layer was 26.7 μm and the film thickness of the surface layer was 53.3 μm. The integral mean heating rate A / B in the drying process of the first coating film was 5.74°C / min.

[0159] Furthermore, endless belt A3 was cut in the same manner as endless belt A1 to obtain an annular body with a diameter of 366 mm and a width of 369 mm. The endless belt thus produced was designated as belt A3. Furthermore, the content of conductive carbon particles in the entire base layer of belt A3 is 22% by mass, and the content of conductive carbon particles in the total solid content of the surface layer is 18% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt A3 were measured using the method described above, the common logarithm of the volume resistivity was 10.8 (logΩ·cm), and the common logarithm of the surface resistivity was 11.2 (logΩ / suq.).

[0160] [Example A4] <Making a Belt A4> Endless belt A4 was obtained in the same manner as endless belt A1, except that in the drying process of the second coating film, the drying process was performed in a 135°C air atmosphere for 15 minutes instead of in a 140°C air atmosphere for 15 minutes. The total film thickness of endless belt A4 (total film thickness of the base layer and surface layer) was 80 μm, of which the film thickness of the base layer was 26.7 μm and the film thickness of the surface layer was 53.3 μm. The integral mean heating rate A / B in the drying process of the first coating film was 5.9°C / min.

[0161] Furthermore, endless belt A4 was cut in the same manner as endless belt A1 to obtain an annular body with a diameter of φ366 mm and a width of 369 mm. The endless belt thus produced was designated as belt A4. Furthermore, the content of conductive carbon particles in the entire base layer of belt A4 is 22% by mass, and the content of conductive carbon particles in the total solid content of the surface layer is 18.2% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt A4 were measured using the method described above, the common logarithm of the volume resistivity was 11.3 (logΩ·cm), and the common logarithm of the surface resistivity was 11.3 (logΩ / suq.).

[0162] [Example B1] <Making Belt B1> The same mold used for the material to be coated, which was used to manufacture the endless belt A1, was prepared and subjected to the same mold release agent treatment. Using the same rotary coating method as used for coating solution A1 in the fabrication of the endless belt A1, coating solution B1 was applied to the outer surface of the material to be coated after the mold release agent treatment to form a first coating film. The first coating film was then dried in a drying oven at 140°C in an air atmosphere while rotating at 10 rpm for 15 minutes. The integral mean heating rate A / B during the drying process of the first coating film was 6.00°C / min.

[0163] Next, the endless belt B1 was obtained by placing it in an oven set to a temperature of 320°C for 4 hours. The total thickness of the endless belt B1 (i.e., the thickness of a single layer) was 80 μm. The endless belt B1 was removed from the mold and cut in the same manner as the endless belt A1 to obtain an annular body with a diameter of 366 mm and a width of 369 mm. The endless belt produced in this way was designated as belt B1. The content of conductive carbon particles relative to the entire belt B1 (i.e., relative to the total solid content of the layer containing resin and conductive particles) is 20% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B1 were measured using the method described above, the common logarithm of the volume resistivity was 11.4 (logΩ·cm), and the common logarithm of the surface resistivity was 11.2 (logΩ / suq.).

[0164] [Example B2] <Making Belt B2> 1000g of all-aromatic polyimide varnish (solids content: 18% by mass, manufactured by Unitika, Yuimide KX, solvent: NMP) was mixed with 36g (20 phr) of carbon black (dry state) [Emperor2000, manufactured by Cabot, number mean primary particle size: 9nm] and a surfactant (Surflon® S-431, in the amount shown in Table 1-1). This mixture was then dispersed using a high-pressure impact disperser (manufactured by Genus) at a pressure of 200 MPa by passing it through a φ0.1 mm orifice and impacting the two divided slurries five times to obtain the first coating solution, coating solution B2.

[0165] The obtained coating solution B2 was applied to the outer surface of a φ366 SUS pipe using a flow-coating method to achieve a predetermined film thickness. After rotational drying at 150°C for 30 minutes, the pipe was placed in a 320°C oven for 4 hours and then removed, resulting in a SUS pipe with an endless belt B2 formed on its outer surface. The total film thickness of the endless belt B2 (i.e., the film thickness of a single layer) was 80 μm. The integral mean heating rate A / B during the drying process was 8.0°C / min.

[0166] The endless belt B2 coated on the outer surface was removed from the SUS pipe and cut to a width of 369 mm to obtain belt B2, which is a belt-shaped intermediate transfer body. The content of conductive carbon particles relative to the entire belt B2 (i.e., relative to the total solid content of the layer containing resin and conductive particles) is 22% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B2 were measured using the method described above, the common logarithm of the volume resistivity was 10.1 (logΩ·cm), and the common logarithm of the surface resistivity was The value was 10.0 (logΩ / suq.).

[0167] [Example B3] <Making Belt B3> An endless belt B3 was obtained in the same manner as in Example B2, except that 37.8 g (21 phr) of carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number average primary particle size: 9 nm] was used and the slurry was subjected to impact 10 times using a high-pressure impact disperser (manufactured by Genus), thereby obtaining belt B3, which is a belt-shaped intermediate transfer body. The total film thickness of endless belt B3 (i.e., the film thickness of a single layer) was 80 μm. The content of conductive carbon particles relative to the entire belt B3 (i.e., relative to the total solid content of the layer containing the resin and conductive particles) was 21.5% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B3 were measured using the method described above, the common logarithm of the volume resistivity was 10.0 (logΩ·cm), and the common logarithm of the surface resistivity was 9.8 (logΩ / suq.).

[0168] [Example B4] <Making Belt B4> An endless belt B4 was obtained in the same manner as in Example B2, except that 39.6 g (22 phr) of carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number average primary particle size: 9 nm] was used and the slurry was subjected to impact 20 times using a high-pressure impact disperser (manufactured by Genus), thereby obtaining belt B4, which is a belt-shaped intermediate transfer body. The total film thickness of endless belt B4 (i.e., the film thickness of a single layer) was 80 μm. The content of conductive carbon particles relative to the entire belt B4 (i.e., relative to the total solid content of the layer containing the resin and conductive particles) was 22.5% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B4 were measured using the method described above, the common logarithm of the volume resistivity was 9.8 (logΩ·cm), and the common logarithm of the surface resistivity was 9.5 (logΩ / suq.).

[0169] [Example B5] <Making Belt B5> An endless belt B5 was obtained in the same manner as in Example B2, except that 43.2 g (24 phr) of carbon black (dry state) (FW285, manufactured by Orion Engineered Carbons, Inc. [number mean primary particle size: 11 nm]) was used as the first conductive particles, and the slurry was subjected to impacts 20 times using a high-pressure impact disperser (manufactured by Genus), thereby obtaining belt B5, which is a belt-shaped intermediate transfer body. The total film thickness of endless belt B5 (i.e., the film thickness of a single layer) was 80 μm. The content of conductive carbon particles relative to the entire belt B5 (i.e., relative to the total solid content of the layer containing the resin and conductive particles) was 24.6% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B5 were measured using the method described above, the common logarithm of the volume resistivity was 9.9 (logΩ·cm), and the common logarithm of the surface resistivity was 9.6 (logΩ / suq.).

[0170] [Example B6] <Making belt B6>

[0171] -Formation and drying of the first coating film- A polyimide precursor solution (coating solution B1) was applied to the outer circumference of a SUS mold with an outer diameter of 366 mm and a thickness of 10 mm using the flow coating method to obtain the desired film thickness, forming a first coating film, which was then dried as follows. Specifically, a slit nozzle (Daiho Kennetsu Co., Ltd.: DLX series, slit width 0.8 mm) installed at the outlet of a downflow type hot air drying oven was used to set the air velocity near the mold to 6 m / s. The mixture was then heated at 200°C for 24 minutes. The integral mean heating rate A / B during the drying process was 5.74°C / min. After drying, the material was fired at 320°C for 4 hours to obtain endless belt B6. The total thickness of endless belt B6 (i.e., the thickness of a single layer) was 80 μm. The obtained endless belt B6 was demolded and cut to a belt width of 369 mm to obtain belt B6. The content of conductive carbon particles relative to the entire belt B6 (i.e., relative to the total solid content of the layer containing resin and conductive particles) is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B6 were measured using the method described above, the common logarithm of the volume resistivity was 11.5 (logΩ·cm), and the common logarithm of the surface resistivity was 11.3 (logΩ / suq.).

[0172] [Example B7] <Making Belt B7> In the drying process, instead of heating at 200°C for 24 minutes using a slit nozzle, the endless belt B7 was obtained in the same manner as the endless belt B6, except that the slit nozzle was used to heat at 235°C for 21 minutes with an air velocity of 6 m / s near the mold. The integral mean heating rate A / B in the drying process was 6.84°C / min, and the total film thickness of the endless belt B7 (i.e., the film thickness of a single layer) was 80 μm. The obtained endless belt B7 was demolded and cut to a belt width of 369 mm to obtain belt B7. The content of conductive carbon particles relative to the entire belt B7 (i.e., relative to the total solid content of the layer containing resin and conductive particles) is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B7 were measured using the method described above, the common logarithm of the volume resistivity was 11.6 (logΩ·cm), and the common logarithm of the surface resistivity was 11.4 (logΩ / suq.).

[0173] [Example B8] <Making Belt B8> In the drying process, instead of heating at 200°C for 24 minutes using a slit nozzle, the endless belt B8 was obtained in the same manner as the endless belt B6, except that the slit nozzle was used to set the air velocity near the mold to 16 m / s and heat at 200°C for 16 minutes. The integral mean heating rate A / B in the drying process was 9.56°C / min, and the total film thickness of the endless belt B8 (i.e., the film thickness of a single layer) was 80 μm. The obtained endless belt B8 was demolded and cut to a belt width of 369 mm to obtain belt B8. The content of conductive carbon particles relative to the entire belt B8 (i.e., relative to the total solid content of the layer containing resin and conductive particles) is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt B8 were measured using the method described above, the common logarithm of the volume resistivity was 11.2 (logΩ·cm), and the common logarithm of the surface resistivity was 11.1 (logΩ / suq.).

[0174] [Example B9] <Making belt B10> -Preparation of coating solution B10 (first coating solution)- • Polyamic acid solution DA-A1 (solid content concentration: 45% by mass) 70 parts by mass • Polyamic acid solution DC-A1 (solid content concentration: 15% by mass) 30 parts by mass • Carbon black (dry state; conductive carbon particles) [Raven5000UltraII, manufactured by Birla, number-average primary particle size: 8nm (hereinafter also abbreviated as "Raven5000")] 18 parts by mass • Surfactant (Surflon® S-651): The amount shown in Table 1-1 (the amount relative to the layer containing the surfactant (the same applies hereinafter)). Polyamic acid solutions DA-A1 and DC-A1 with the above compositions were mixed, and a surfactant was added along with Raven 5000. The mixture was dispersed in a ball mill at 30°C for 12 hours. The mixture containing dispersed Raven 5000 was then filtered through an #800 stainless steel mesh to obtain the first coating solution, coating solution B10. A film was formed using coating solution B10 in the same manner as with B1 to obtain an endless belt B10. The total film thickness of the endless belt B10 (i.e., the film thickness of a single layer) was 80 μm. Furthermore, the volume resistivity and surface resistivity of the outer surface of belt B10 were measured using the method described above. The common logarithm of the volume resistivity was 11.1 (logΩ·cm), and the common logarithm of the surface resistivity was 11.0 (logΩ / suq.).

[0175] [Example C1] <Making Belt C1> Aromatic polyamide-imide varnish (solids content 18 wt%, manufactured by Hitachi Chemical, HPC-9000) To 1000g of solvent (NMP), 37.8g (22 phr) of carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number mean primary particle diameter: 9nm] was added, along with a surfactant (Surflon® S-431) in the amounts shown in Table 1-1. This mixture was then dispersed using a high-pressure impingement disperser (manufactured by Genus) at a pressure of 200 MPa by passing it through a φ0.1 mm orifice and repeatedly impacting the two divided slurries 10 times to obtain the first coating solution, coating solution C1.

[0176] The same mold used for the material to be coated, which was used to manufacture the endless belt A1, was prepared and subjected to the same mold release agent treatment. The coating liquid C is applied using the same rotary coating method as when applying coating liquid A1 in the manufacture of the endless belt A1. After applying 1 to the outer surface of the material to be coated after the mold release agent treatment described above to form a first coating film, the first coating film was dried in a drying oven at 150°C in an air atmosphere while rotating at 10 rpm for 15 minutes. The integral mean heating rate A / B during the drying process of the first coating film was 6.0°C / min.

[0177] Next, the endless belt C1 was obtained by placing it in an oven set to a temperature of 290°C for 4 hours. The total thickness of the endless belt C1 (i.e., the thickness of a single layer) was 80 μm. The endless belt C1 was removed from the mold and cut in the same manner as the endless belt A1 to obtain an annular body with a diameter of 366 mm and a width of 369.5 mm. The endless belt produced in this manner was designated as belt C1. The content of conductive carbon particles in the entire belt C1 is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt C1 were measured using the method described above, the common logarithm of the volume resistivity was 11.2 (logΩ·cm), and the common logarithm of the surface resistivity was 11.2 (logΩ / suq.).

[0178] [Example C2] <Fabrication of Belt C2> Aromatic polyamide-imide varnish (solid content 18 wt%, manufactured by Hitachi Chemical, HPC-9000) To 1000g of solvent (NMP), 37.8g (22 phr) of carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number average primary particle diameter: 9nm] was added, along with a surfactant (Surflon® S-431) in the amount shown in Table 1-1. This mixture was then dispersed using a high-pressure impingement disperser (manufactured by Genus) by passing it through a φ0.1mm orifice at a pressure of 200MPa and repeatedly impacting the two divided slurries 10 times, thereby obtaining the first coating solution, coating solution C2.

[0179] The obtained coating solution C2 was applied to the outer surface of a φ366 SUS pipe using a flow-coating method to achieve a predetermined film thickness. After rotational drying at 150°C for 30 minutes, the pipe was placed in a 290°C oven for 1 hour and then removed, resulting in a SUS pipe with an endless belt C2 formed on its outer surface. The total film thickness of the endless belt C2 (i.e., the film thickness of a single layer) was 80 μm. The integral mean heating rate A / B during the drying process was 7.2°C / min.

[0180] The endless belt C2, coated on its outer surface, was removed from the SUS pipe and cut to a width of 369 mm to obtain belt C2, which is a belt-shaped intermediate transfer body. The conductive carbon particle content of belt C2 as a whole is 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt C2 were measured using the method described above, the common logarithm of the volume resistivity was 10.3 (logΩ·cm), and the common logarithm of the surface resistivity was 10.2 (logΩ / suq.).

[0181] [Example C3] <Fabrication of Belt C3> An endless belt C3 was obtained in the same manner as in Example C2, except that 36 g (20 phr) of carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number average primary particle diameter: 9 nm] was used as the first conductive carbon particles, and the slurry was subjected to impacts 20 times using a high-pressure impact disperser (manufactured by Genus), thereby obtaining belt C3, which is a belt-shaped intermediate transfer body. The total film thickness of endless belt C3 (i.e., the film thickness of a single layer) was 80 μm. The content of conductive carbon particles in the total belt C3 was 19% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt C3 were measured using the method described above, the common logarithm of the volume resistivity was 10.1 (logΩ·cm), and the common logarithm of the surface resistivity was 9.9 (logΩ / suq.).

[0182] [Example D1] <Fabrication of endless belt D1> PEEK resin (Victrex, 450G) pellets, carbon black (dry state, first conductive particles, Emperor2000, Cabot, number average primary particle size: 9nm), and surfactant (Surflon® S-431) were mixed in a Henschel mixer (Nippon Coke, FM10C) with 180g of PEEK resin and 27g (15 phr) of carbon black, so that the amount of surfactant was as shown in Table 1-1. The mixed composition was melt-kneaded in a twin-screw extruder (L / D60 (Parker Corporation)), extruded into a string shape through a φ5 hole, cooled and solidified in a water tank, and then cut to obtain mixed resin pellets containing furnace black. The resulting mixed resin pellets were fed into a uniscrew molten extruder (L / D24, molten extrusion device (manufactured by Mitsuba Seisakusho Co., Ltd.)) set to a predetermined temperature (380°C), and extruded in a cylindrical shape through the gap between the annular die and the nipple while melting. To fix the cylindrical shape and diameter of the extruded cylindrical film while taking it up, the inner surface of the cylindrical film was brought into contact with a sizing die (cooling mold) set to a predetermined temperature (50°C) to cool it and obtain an endless belt D1. The endless belt D1 was removed from the cooling mold, stretched over a holder, and cut with a cutter whose insertion angle was adjusted to obtain an annular body with a diameter of 366 mm and a width of 369 mm. The endless belt thus produced was designated as belt D1. The total film thickness of belt D1 (i.e., the film thickness of a single layer) was 80 μm. The conductive carbon particle content relative to the entire belt D1 is 13% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt D1 were measured using the method described above, the common logarithm of the volume resistivity was 11.1 (logΩ·cm), and the common logarithm of the surface resistivity was 11.3 (logΩ / suq.).

[0183] [Example E1] <Fabrication of endless belt E1> PPS resin (Toray Industries, Ltd., Torelina T1881) powder, carbon black [dry state, first conductive particles, Emperor2000, manufactured by Cabot, number average primary particle size: 9 nm], and surfactant (Surflon® S-431) were added to a Henschel mixer (Nippon Coke Co., Ltd., FM10C) in a ratio of 180 g of PPS resin and 27 g (15 phr) of carbon black, so that the amount of surfactant was as shown in Table 1-1, and mixed. The mixed composition was melt-kneaded in a twin-screw extruder (L / D60 (manufactured by Parker Corporation)), extruded into a string shape through a φ5 hole, cooled and solidified in a water tank, and then cut to obtain mixed resin pellets containing carbon black. The resulting mixed resin pellets were fed into a uniscrew melt extruder (L / D24, melt extrusion device (manufactured by Mitsuba Seisakusho Co., Ltd.)) set to a predetermined temperature (350°C), and extruded into a cylindrical shape through the gap between the annular die and the nipple while melting. To fix the cylindrical shape and diameter of the extruded cylindrical film while taking it up, the inner surface of the cylindrical film was brought into contact with a sizing die (cooling mold) set to a predetermined temperature (50°C) to cool it and obtain an endless belt E1. The endless belt E1 was removed from the cooling mold, stretched over a holder, and cut with a cutter whose insertion angle was adjusted to obtain an annular body with a diameter of 366 mm and a width of 369 mm. The endless belt thus produced was designated as belt E1. The total film thickness of belt E1 (i.e., the film thickness of a single layer) was 80 μm. The conductive carbon particle content relative to the entire belt E1 is 13% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt E1 were measured using the method described above, the common logarithm of the volume resistivity was 10.9 (logΩ·cm), and the common logarithm of the surface resistivity was 11.2 (logΩ / suq.).

[0184] [Comparative Example F1] <Making a Belt F1> The same mold as the coated material used for manufacturing the endless belt A1 was prepared, and the same mold release agent treatment was performed. By the same spin coating method as the coating of the coating liquid A1 in the production of the endless belt A1, the coating liquid A1 was applied to the outer peripheral surface of the coated material after the mold release agent treatment to form a coating film, and then the coating film was dried in a drying oven at 140 °C in an air atmosphere for 15 minutes while rotating at 10 rpm. Next, it was placed in an oven with a reaching temperature of 320 °C for 4 hours to obtain an endless belt F1. The overall film thickness (i.e., the film thickness of a single layer) of the endless belt F1 was 80 μm. The endless belt F1 was removed from the mold and cut in the same manner as the endless belt A1 to obtain an annular body with a diameter of φ366 mm and a width of 369.5 mm. The endless belt thus produced was designated as belt F1. Note that the content of conductive carbon particles in the entire belt F1 is 19% by mass. When the volume resistivity and the surface resistivity of the outer peripheral surface of the belt F1 were measured by the above-described method, the common logarithm value of the volume resistivity was 11.1 (logΩ·cm), and the common logarithm value of the surface resistivity was 11.1 (logΩ / suq.).

[0185] [Comparative Example F2] <Production of Belt F2> In the drying process, instead of heating at 200 °C for 24 minutes using a slit nozzle, the hot air in the drying oven was directly supplied to the first coating film without using a slit nozzle, the wind speed near the mold was set to 0.8 m / s, and an endless belt F2 was obtained in the same manner as the endless belt B6 except that it was heated at 200 °C for 28 minutes. The integrated average heating rate A / B was 3.55 °C / min, and the overall film thickness (i.e., the film thickness of a single layer) of the endless belt F2 was 80 μm. The obtained endless belt F2 was demolded and cut to a belt width of 369 mm to obtain belt F2. The content of conductive carbon particles in the entire belt F2 is 19% by mass. When the volume resistivity and the surface resistivity of the outer peripheral surface of the belt F2 were measured by the above-described method, the common logarithm value of the volume resistivity was 11.8 (logΩ·cm), and the common logarithm value of the surface resistivity was 13.1 (logΩ / suq.).

[0186] [Comparative Example F3] <Making Belt F3> In the drying process, instead of heating at 200°C for 24 minutes using a slit nozzle, the hot air from the drying oven was supplied directly to the first coated film without using a slit nozzle, the air velocity near the mold was set to 0.9 m / s, and the film was heated at 235°C for 24 minutes. Except for these differences, the endless belt F3 was obtained in the same manner as the endless belt B6. The integral mean heating rate A / B was 4.36°C / min, and the total film thickness of the endless belt F3 (i.e., the film thickness of a single layer) was 80 μm. The obtained endless belt F3 was demolded and cut to a belt width of 369 mm to obtain belt F3. The conductive carbon particle content of belt F3 as a whole is 18% by mass. Furthermore, when the volume resistivity and surface resistivity of the outer surface of belt F3 were measured using the method described above, the common logarithm of the volume resistivity was 12.2 (logΩ·cm), and the common logarithm of the surface resistivity was 12.8 (logΩ / suq.).

[0187] [Examples G1-G13] <Making belts G1-G13> Belts G1 to G12 were obtained in the same manner as the example belts shown in Table 1-2 (indicated as "base example" in the table), except that the type and amount of surfactant (amount relative to the layer containing the surfactant (mass %)) shown in Table 1-2 were changed.

[0188] [Comparative Examples H1, H2] <Manufacturing of belts H1 and H2> Belts H1 to H2 were obtained in the same manner as the example belts shown in Table 1-2 (indicated as "base example" in the table), except that the type and amount of surfactant shown in Table 1-2 were changed.

[0189] [Activating agents used in Examples G1-G13 and Comparative Examples H1-H3] • Surflon (registered trademark) S-431: Manufactured by AGC Seimi Chemical Co., Ltd., an oligomer having a perfluoroalkyl structure with 5 carbon atoms (an oligomer with 30 repeating units of a monomer having a perfluoroalkyl structure with 5 carbon atoms). • F-Tergent 601ADH: Manufactured by Neos Corporation, an oligomer having a perfluoroalkyl structure with 5 carbon atoms (an oligomer with 200 repeating units of a monomer having a perfluoroalkyl structure with 5 carbon atoms). • KP126: Manufactured by Shin-Etsu Chemical Co., Ltd., an oligomer with a silicone structure containing methyl groups (500 repeating siloxane units). • KP109: Manufactured by Shin-Etsu Chemical Co., Ltd., an oligomer with a silicone structure containing methyl groups (500 repeating siloxane units). • Ogusol SI 10-10: Manufactured by Osaka Gas Chemical Co., Ltd., an oligomer having a silane structure with methyl and phenyl groups (10 repeating silane units). • FC4430: Manufactured by 3M, an oligomer having a perfluoroalkyl structure with 4 carbon atoms (an oligomer with 10 repeating units of a monomer having a perfluoroalkyl structure with 4 carbon atoms) • FC4432: Manufactured by 3M, an oligomer having a perfluoroalkyl structure with 4 carbon atoms (an oligomer with 10 repeating units of a monomer having a perfluoroalkyl structure with 4 carbon atoms) • Surflon® S-656: Manufactured by AGC Seimi Chemical Co., Ltd., an oligomer having a perfluoroalkyl structure with 5 carbon atoms (an oligomer with 30 repeating units of a monomer having a perfluoroalkyl structure with 5 carbon atoms) In Tables 1-1 and 1-2, the column for the number of carbon atoms in the surfactant indicates the number of carbon atoms in the perfluoroalkyl structure, the substituent (methyl group) of the siloxane, and the substituent (phenyl group) of the silane.

[0190] [Characteristic evaluation of endless belts] The following characteristics were determined for each endless belt obtained in the example, according to the method described above. The results are shown in Tables 1-1 and 1-2. The discharge initiation voltage (referred to as "discharge initiation voltage") of a layer containing resin and conductive particles (or the surface layer in the case of a laminate having multiple such layers). ·Potential decay rate (V / msec) • Spray pressure P0 (0 g / cm²) applied to the outer surface of an endless belt with polyester resin particles having a volume-average particle size of 4.7 μm. 2After adhesion, air is blown onto the outer surface from above, increasing the blowing pressure. The air pressure shown is the pressure at which all the polyester resin particles attached to the outer surface are separated from the outer surface. • Spray pressure P46 (46 g / cm² applied to the outer surface of an endless belt with polyester resin particles having a volume-average particle size of 4.7 μm) 2 After adhesion, air is blown onto the outer surface from above, increasing the blowing pressure. The pressure shown is the air pressure at which all polyester resin particles attached to the outer surface are separated from the outer surface. • Surface free energy (mN / m) of the outer surface of the endless belt • Water contact angle (°) of the outer surface of the endless belt • Diiodomethane contact angle (°) on the outer surface of the endless belt The layer structure of the endless belt, the type of resin contained in the first layer, the number-average primary particle diameter of the conductive particles contained in the first layer, the surfactant content relative to the total solid content of the first layer, the type of surfactant, and the number of carbon atoms are also shown in Tables 1-1 to 1-2.

[0191] [Evaluation of endless belts (1)] <Evaluation of transferability to textured paper (11)> The endless belts obtained in each example were incorporated as intermediate transfer belts into a modified DocuColor-7171P machine (i.e., a modified machine in which the cleaning blade was adjusted to match the belt thickness after the intermediate transfer belt was installed). Under conditions of a temperature of 22°C and a humidity of 10%RH, and a recording medium transport speed of 366 mm / s in the secondary transfer area, a solid blue image was formed on textured paper (Lezack 66, 204 gsm), and the white areas in the recesses were visually evaluated. The evaluation criteria are as follows, and the results are shown in Tables 1-1 to 1-2. In this evaluation, the transferability to textured paper, which is specialized in electrostatic adhesion, was evaluated by setting the temperature and humidity environment as described above. Furthermore, a conductive roll (1), described later, was used as the primary transfer roll. Furthermore, the contact width between the intermediate transfer belt and the secondary transfer roll (simply referred to as "contact width" in the table) was set to the widths shown in Tables 1-1 to 1-2. Also, as the toner, a toner having a volume average particle diameter of 4.7 μm was used.

[0192] -Evaluation Criteria- A: No white voids occurred B: Some color variations occurred B-: No distinct color variations occurred, but color variations occurred more than in criterion B C: Distinct color variations occurred D: White voids occurred

[0193] <Evaluation of Transferability to Embossed Paper (12)> Evaluation was performed in the same manner as the evaluation of transferability to embossed paper (11), except that the conveyance speed of the recording medium in the secondary transfer area was set to 524 mm / s.

[0194] <Production of Conductive Roll (1)> 40 parts by mass of epichlorohydrin-allyl glycidyl ether binary copolymer (ECO) (manufactured by Nippon Zeon Co., Ltd., trade name: Zexron 1100) 60 parts by mass of acrylonitrile-butadiene rubber (NBR) (manufactured by Nippon Zeon Co., Ltd., trade name: Nipol DN223) 6 parts by mass of foaming agent (benzenesulfonyl hydrazide) 1 part by mass of vulcanizing agent (manufactured by Tsurumi Chemical Industry Co., Ltd., trade name: sulfur, 200 mesh) 1.5 parts by mass of vulcanization accelerator (manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Nocceler M)

[0195] The rubber composition containing each of the above components was kneaded with an open roll. The kneaded rubber composition was extruded in a state where a hole was opened in the central part (doughnut shape) and formed into a cylindrical roll. Next, the cylindrical roll was heated at 160 °C for 20 minutes to cause vulcanization foaming, and the conductive roll (1) was obtained.

Table 1-1

[0196]

Table 1-2

[0197] From the above results, it can be seen that this embodiment exhibits superior transferability to textured paper compared to the comparative example.

[0198] [Evaluation of endless belts (2)] For the endless belts shown in Table 2, the relationship between the contact width between the intermediate transfer belt and the secondary transfer member was evaluated. Specifically, the results are as follows:

[0199] <Evaluation of transferability to textured paper (21)> The endless belts obtained in each example were incorporated as intermediate transfer belts into a modified DocuColor-7171P machine (i.e., a modified machine in which the cleaning blade was adjusted to match the belt thickness after the intermediate transfer belt was installed). This modified machine is a device equipped with a secondary transfer roll as a secondary transfer component. Then, the contact width between the intermediate transfer belt and the secondary transfer roll was set to the width shown in Table 2, and under conditions of a temperature of 22°C and a humidity of 10%RH, and a transport speed of the recording medium in the secondary transfer area of ​​366 mm / s, a solid blue image was formed on textured paper (Lezac 66, 204 gsm), and the white areas in the recesses were visually evaluated. The evaluation criteria were the same as for transferability evaluation (1), and the results are shown in Table 2. In this evaluation, by setting the temperature and humidity environment as described above, the transferability to textured paper, which is specifically focused on electrostatic adhesion, was evaluated. Furthermore, the aforementioned conductive roll (1) was used as the primary transfer roll. Furthermore, a toner with a volume-average particle size of 4.7 μm was used.

[0200] <Evaluation of transferability to textured paper (22)> The endless belt shown in Table 2 was incorporated as an intermediate transfer belt into a modified DocuColor-7171P machine (i.e., a modified machine in which a secondary transfer unit equipped with a secondary transfer belt and an intermediate transfer belt were installed, and the cleaning blade was adjusted to match the belt thickness). This modified machine is a device equipped with a secondary transfer belt as a secondary transfer component. Then, the contact width between the intermediate transfer belt and the secondary transfer belt was set to the width shown in Table 2, and under conditions of a temperature of 22°C and a humidity of 10%RH, and a transport speed of the recording medium in the secondary transfer area of ​​366 mm / s, a solid blue image was formed on textured paper (Lezack 66, 204 gsm), and the white areas in the recesses were visually evaluated. The evaluation criteria were the same as for transferability evaluation (1), and the results are shown in Table 2. In this evaluation, by setting the temperature and humidity environment as described above, the transferability to textured paper, which is specifically focused on electrostatic adhesion, was evaluated. Furthermore, the aforementioned conductive roll (1) was used as the primary transfer roll. Furthermore, a toner with a volume-average particle size of 4.7 μm was used.

[0201] [Table 2]

[0202] From the above results, it can be seen that this embodiment exhibits superior transferability to uneven paper even when the contact width between the intermediate transfer belt and the secondary transfer member is wider compared to the comparative example. [Explanation of Symbols]

[0203] 1Y, 1M, 1C, 1K Image Forming Unit 10 Primary Transfer Section 11 Photoreceptor 12 Chargers 13. Laser exposure unit 14. Developer 15 Intermediate transfer belt 16 Primary transfer roll 17 Photoconductor Cleaner 20 Secondary transfer section 22 Secondary transfer roll 22A Secondary transfer roll cleaning member 25 Back Roll 26 Power supply roll 31 Drive Roll 32 support rolls 33 Tension-applying roll 34 Cleaning back roll 35 Intermediate transfer belt cleaning member 40 Control Unit 42 Reference Sensor 43 Image density sensor 50 Paper storage compartments 51 Paper feed roll 52 Conveyor Rolls 53 Conveyor Guide 55 Conveyor belt 56 Fixing entrance guide 60 Fixing device 100 Image forming apparatus

Claims

1. It has a surface layer containing resin and conductive particles, The number-average primary particle diameter of the conductive particles is 11 nm or less. Polyester resin particles with a volume-average particle diameter of 4.7 μm are applied to the outer surface under a load of 0 g / cm². ２ After adhesion, when air is blown onto the outer surface from above while increasing the blowing pressure, all the polyester resin particles attached to the outer surface separate from the outer surface when the blowing pressure is 6 kPa or less. An endless belt in which, when a voltage is applied to the surface layer, the discharge initiation voltage from the application of voltage to the start of discharge is 0.9 kV or higher (however, the discharge initiation voltage is the applied voltage at which discharge begins when a 3 cm x 4 cm test piece taken from the surface layer of the endless belt is placed on one electrode, the other electrode is positioned with a space gap of 60 μm relative to the test piece, and the applied voltage is increased at 1.67 V / s).

2. The endless belt according to claim 1, wherein the number-average primary particle diameter of the conductive particles is 8 nm or more and 10 nm or less.

3. The endless belt according to claim 1 or claim 2, wherein the conductive particles include conductive carbon particles.

4. The endless belt according to any one of claims 1 to 3, wherein the content of the conductive particles is 10% by mass or more and 30% by mass or less with respect to the total solid content of the surface layer.

5. The endless belt according to any one of claims 1 to 4, wherein the surface layer further comprises a surfactant.

6. The endless belt according to claim 5, wherein the content of the surfactant is 1% by mass or more and 6% by mass or less with respect to the total solid content of the surface layer.

7. The endless belt according to claim 5 or claim 6, wherein the surfactant is at least one of an oligomer having a substituent with 6 or fewer carbon atoms and a fluorine atom, and an oligomer having a silicone structure with a methyl group.

8. The endless belt according to claim 7, wherein the oligomer having a substituent with 6 or fewer carbon atoms and a fluorine atom is an oligomer having a perfluoroalkyl structure with 6 or fewer carbon atoms.

9. The endless belt according to claim 7 or claim 8, wherein the number of repeating units of monomer in the oligomer is 4 or more.

10. The endless belt according to any one of claims 1 to 9, wherein the surface free energy of the outer surface of the endless belt is 47 mN / m or less.

11. The endless belt according to any one of claims 1 to 10, wherein the water contact angle of the outer surface of the endless belt is 85° or more.

12. The endless belt according to any one of claims 1 to 11, wherein the diiodomethane contact angle of the outer surface of the endless belt is 40° or more.

13. The polyester resin particles are applied to the outer surface under a load of 0 g / cm². ２ and 46 g / cm ２ An endless belt according to any one of claims 1 to 12, wherein, after adhesion, air is blown onto the outer surface from above the outer surface while increasing the blowing pressure, and the relationship between the air blowing pressure when all the polyester resin particles attached to the outer surface are separated from the outer surface satisfies the relationship shown by the following formula (P). Formula (P): Spray pressure P46 / Spray pressure P0 ≤ 1.5 In formula (P), P0 is the amount of polyester resin particles under a load of 0 g / cm². ２ After adhesion, P46 indicates the air blowing pressure at which all the polyester resin particles attached to the outer surface are separated from the outer surface, and P46 is the pressure at which the polyester resin particles are subjected to a load of 46 g / cm². ２ This indicates the air blowing pressure at which, after adhesion, all the polyester resin particles attached to the outer surface are separated from the outer surface.

14. An intermediate transfer body on which a toner image is transferred to its outer surface, comprising an intermediate transfer body having an endless belt as described in any one of claims 1 to 13, A primary transfer apparatus having a primary transfer member that primarily transfers a toner image formed on the surface of an image holder to the outer peripheral surface of an intermediate transfer body, A secondary transfer apparatus having a secondary transfer member that is positioned in contact with the outer peripheral surface of the intermediate transfer body and secondary transfers the toner image transferred to the outer peripheral surface of the intermediate transfer body to the surface of the recording medium, A transfer device equipped with the following features.

15. The transfer apparatus according to claim 14, wherein the secondary transfer member is a secondary transfer roll, and the contact width between the intermediate transfer body and the secondary transfer roll is 0.2 cm or more and 4.0 cm or less.

16. The transfer apparatus according to claim 15, wherein the secondary transfer member is a secondary transfer roll, and the contact width between the intermediate transfer body and the secondary transfer roll is 0.2 cm or more and 2.8 cm or less.

17. A toner image forming apparatus having an image holder and forming a toner image on the surface of the image holder, A transfer apparatus for transferring the toner image formed on the surface of the image holder to the surface of a recording medium, comprising the transfer apparatus according to any one of claims 14 to 16, An image forming apparatus equipped with the following features.

Images