Electrophotographic belt and electrophotographic image forming apparatus

Abstract

The present invention relates to an electrophotographic belt and an electrophotographic image forming apparatus. An electrophotographic belt in which the oozing out of a cationic component to the outer surface is suppressed after long-term storage after long-term repeated image output. The electrophotographic belt has a layer including a thermoplastic resin composition, the thermoplastic resin composition including a hot melt kneaded product of a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule.

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic belt and an electrophotographic image forming apparatus including the electrophotographic belt. Background Art

[0002] Japanese Patent Application Laid-Open No. 2015-230456 discloses a conductive tape that is highly conductive and has little resistance fluctuation even after long-term use. The conductive tape includes a hydrophobic fluorinated sulfonylimide structure or an ionic liquid having hexafluorophosphate as an anion in a thermoplastic resin such as polyester.

[0003] According to research, when an electrophotographic belt according to Japanese Patent Application Laid-Open No. 2015-230456 was used as an intermediate transfer belt to form an electrophotographic image for a long time and then left for a predetermined time, image failure due to poor transfer of toner was observed when it was used again to form an electrophotographic image. Summary of the invention

[0004] At least one aspect of the present disclosure is intended to provide an electrophotographic belt, wherein even after long-term image formation and then long-term storage, cationic components are difficult to exude to the surface, which contributes to the stable formation of high-quality electrophotographic images. In addition, at least one aspect of the present disclosure is intended to provide an electrophotographic image forming device capable of stably forming high-quality electrophotographic images. In addition, at least one aspect of the present disclosure is intended to provide a method for producing an electrophotographic belt, for which cationic components are difficult to exude to the surface even after long-term image formation and then long-term storage, which contributes to the stable formation of high-quality electrophotographic images.

[0005] According to one aspect of the present disclosure, there is provided an electrophotographic belt having a first layer including a thermoplastic resin composition, wherein the thermoplastic resin composition comprises a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule. According to another aspect of the present disclosure, there is provided an electrophotographic image forming device comprising the above-mentioned electrophotographic belt as an intermediate transfer belt. According to yet another aspect of the present disclosure, there is provided a method for producing an electrophotographic belt having an annular shape and provided with a first layer including a thermoplastic resin composition, the method comprising the following steps: (i) hot-melt kneading a thermoplastic polyester resin, an ionic compound including a cation and anion having a hydroxyl group, and an amide compound having at least two amide groups in one molecule to form a thermoplastic resin composition; and (ii) forming the thermoplastic resin composition into an annular belt shape.

[0006] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic cross-sectional view showing an example of a full-color electrophotographic image forming apparatus utilizing an electrophotographic method.

[0008] Figure 2 is a schematic cross-sectional view of an injection molding apparatus used in the embodiment.

[0009] Figure 3 : is an explanatory schematic diagram of the primary blow molding apparatus used in the examples.

[0010] Figure 4 is an explanatory schematic diagram of a secondary blow molding apparatus used in Examples.

[0011] Figure 5 This is a diagram for explaining the mechanism by which the electrophotographic belt according to the present disclosure exerts its effects.

[0012] Fig. 6A , Figure 6B and Figure 6C It is an explanatory diagram of a configuration example of the electrophotographic belt according to the present disclosure. DETAILED DESCRIPTION

[0013] The present inventors have studied image defects that occur when the above-mentioned electrophotographic belt according to Japanese Patent Application Laid-Open No. 2015-230456 is used as an intermediate transfer belt for forming electrophotographic images. Specifically, the portion corresponding to the position of the image defect on the toner bearing surface of the electrophotographic belt was observed. As a result, untransferred toner and adhesive attachments were confirmed. Further elemental analysis of the attachments confirmed that the attachments were cationic components of the ionic liquid contained in the electrophotographic belt. Thus, in order to more stably form high-quality electrophotographic images, the present inventors realized that it was necessary to develop a technology that further suppresses the seepage (bleeding) of cationic components in the electrophotographic belt that conducts electricity with an ionic liquid.

[0014] Herein, it is presumed that the reason why the cationic component seeps out on the belt surface after the electrophotographic belt according to Japanese Patent Application Laid-Open No. 2015-230456 is repeatedly used to output images for a longer time than before and stored for a long time is as follows.

[0015] That is, the polyester resin contained in the thermoplastic resin composition is not completely compatible with the cations and anions, and microscopically, the polyester resin phase is mixed with the cations and anions. Therefore, depending on the direction of voltage application, one of the cations and anions moves toward one surface of the belt, and the other moves toward the other surface (back side) of the belt.

[0016] The formation process of the electrophotographic image has a primary transfer in which the toner on the photosensitive drum is transferred to the electrophotographic belt; and a secondary transfer in which the toner on the electrophotographic belt is transferred to a transfer medium. For the primary transfer and the secondary transfer, the directions of the voltages applied to the electrophotographic belt are opposite to each other in the thickness direction of the electrophotographic belt.

[0017] Since the amount of energization caused by applying voltage in opposite directions in the primary transfer and the secondary transfer is generally different, the cations and anions in the thickness direction tend to be unevenly distributed in one direction. Therefore, the image is repeatedly outputted for a longer time than before, whereby the cations and anions are unevenly distributed near the belt surface.

[0018] When the electrophotographic belt is stored for a long time in such a state, a force for moving the cationic components toward the outer surface of the electrophotographic belt is applied in an attempt to reduce the difference in interfacial energy between the outer surface of the electrophotographic belt and the atmosphere, and the cationic components seep out on the outer surface of the electrophotographic belt.

[0019] The present inventors have repeatedly studied to suppress the exudation of such cations. As a result, the present inventors have found that the exudation of cationic components to the outer surface can be better suppressed by an electrophotographic belt having a layer including a thermoplastic resin composition including a hot melt kneaded product of a thermoplastic polyester resin (hereinafter, also simply referred to as "polyester resin"), a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule.

[0020] Figure 5 The assumed mechanism by which the bleed-out of the cationic component can be better suppressed by the electrophotographic belt having the above-mentioned configuration is described. Figure 5 The cation 501 having a hydroxyl group, the polyethylene naphthalate 502 as a polyester resin, and the ethylene bisstearic acid amide 503 as a compound having at least two amide groups in one molecule shown in FIG. 5 are merely examples, and the present disclosure is not limited to these compounds.

[0021] The cation 501 having a hydroxyl group and the polyester resin 502 interact with each other through a hydrogen bond or an ester exchange reaction between the hydroxyl group 501-1 and the ester bond 502-1 of the polyester resin 502 (refer to Figure 5In addition, the cation 501 having a hydroxyl group and the compound having at least two amide groups in one molecule (hereinafter, sometimes referred to as "amide compound") 503 interact with each other between the hydroxyl group 501-1 and the amide group 503-1 (refer to Figure 5 In addition, the amide compound 503 and the polyester resin 502 interact with each other between the amide group 503-1 and the ester bond 502-1 of the polyester resin (refer to Figure 5 As described above, it is considered that the amide compound 503 having two or more amide groups in one molecule promotes further improvement in affinity between the cationic component 501 having a hydroxyl group and the polyester resin 502. Figure 5 The arrows A, B, and C in illustratively show one aspect of the interaction between the hydroxyl group, the ester bond, and the amide group, and in reality, it is believed that these functional groups and bonds interact with each other in a complex manner. Figure 5 In the above formula (a), n, p, and q each independently represent an integer of 1 or more, and R1 and R2 each independently represent a hydrogen atom or an organic group.

[0022] In addition, if Figure 5 As shown in , when the above-mentioned cation has two or more hydroxyl groups, the interaction between the polyester resin and the amide compound is further enhanced, whereby the oozing out of the cation to the outer surface of the electrophotographic belt can be further suppressed.

[0023] In addition, even when the first layer contains polyetheresteramide (PEEA) as an optional component, PEEA includes an ester bond and an amide group in the molecule, so the mechanism as described above can suppress the oozing of PEEA to the outer surface of the electrophotographic belt. In this regard, PEEA is used as a polymer ion conductive agent and is therefore a preferred component for further improving the conductivity of the first layer of the electrophotographic belt.

[0024] The electrophotographic belt according to one aspect of the present disclosure has a layer including a thermoplastic resin composition, the thermoplastic resin composition comprising a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a hot melt kneaded product of a compound having at least two amide groups in one molecule. In this specification, a compound having a cation and a paired anion may be referred to as an "ionic compound".

[0025] <Thermoplastic resin composition>

[0026] The thermoplastic resin composition according to the present disclosure includes a hot melt kneading product of a thermoplastic polyester resin, a cation having a hydroxyl group, an anion, and a compound having at least two amide groups in one molecule. For example, the hot melt kneading product can be obtained by melt kneading the components including the thermoplastic polyester resin, the cation having a hydroxyl group, anion, and a compound having at least two amide groups in one molecule. The above-mentioned PEEA can also be hot melt kneaded with these components.

[0027] Hot melt mixing refers to heating and mixing the resin contained in the thermoplastic resin composition under molten conditions. During hot melt mixing, the resin with the highest melting point among the resins contained in the thermoplastic resin composition can be mixed at a temperature above the highest melting point so as to mix well. There is no particular limitation on the mixing method, and a single screw extruder, a twin screw mixing extruder, a Banbury mixer, a roller, a Brabender, a plastometer, or a kneader can be used.

[0028] <Thermoplastic polyester resin>

[0029] Thermoplastic polyester resins can be obtained by polycondensation of dicarboxylic acids and diols, polycondensation of hydroxycarboxylic acids or lactones, or polycondensation of a plurality of these components. Other multifunctional monomers can be used in combination. Thermoplastic polyester resins can be homopolyesters including one ester bond or can be copolyesters (copolymers) including a plurality of ester bonds.

[0030] Preferred examples of the thermoplastic polyester resin include at least one selected from the group consisting of polyalkylene terephthalate and polyalkylene naphthalate having high crystallinity and excellent heat resistance. In addition, a copolymer of polyalkylene terephthalate or polyalkylene naphthalate and polyalkylene isophthalate may be preferably used as a copolyester (copolymer).

[0031] The above copolymer may be in the form of a block copolymer or a random copolymer.

[0032] From the viewpoint of high crystallinity and heat resistance, in polyalkylene terephthalate, polyalkylene naphthalate, and polyalkylene isophthalate, the carbon number of the alkylene group is preferably 2 or more and 16 or less. More specifically, polyethylene terephthalate, polyethylene naphthalate, and a copolymer of polyethylene terephthalate and polyethylene isophthalate are preferred as the thermoplastic polyester resin.

[0033] The intrinsic viscosity of the thermoplastic polyester resin is preferably 1.4 dl / g or less, more preferably 0.3 dl / g or more and 1.2 dl / g or less. A thermoplastic polyester resin having an intrinsic viscosity of 1.4 dl / g or less has excellent fluidity during a hot melt kneading step. When the intrinsic viscosity is 0.3 dl / g or more, the strength and durability of the belt for electrophotography can be more easily improved. The intrinsic viscosity of the thermoplastic polyester resin is a value measured under the conditions that o-chlorophenol is used as a diluting solvent for the thermoplastic polyester resin, the o-chlorophenol solution concentration of the thermoplastic polyester resin is 0.5 mass%, and the temperature is 25°C.

[0034] In addition, the content of the thermoplastic polyester resin in the thermoplastic resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more relative to the total mass of the thermoplastic resin composition. Setting the content of the thermoplastic polyester resin to 50% by mass or more relative to the total mass of the thermoplastic resin composition makes it easy to improve the mechanical strength of the thermoplastic resin composition.

[0035] <Cation having a hydroxyl group>

[0036] There is no particular limitation on the cation having a hydroxyl group, and examples thereof include ammonium ions, imidazolium ions, pyridinium ions, piperidinium ions, pyrrolidinium ions, and phosphonium ions. Among them, ammonium ions and imidazolium ions are preferred from the viewpoint of, for example, cost.

[0037] Specific examples of the above cations include 2-hydroxyethylammonium ion, 2-hydroxypropylammonium ion, 2-hydroxyethyl-trimethylammonium ion, 2-hydroxypropyl-trimethylammonium ion, 2-hydroxy-3-methacryloyloxypropyltrimethylammonium ion, and N-oleyl-N,N-di(2-hydroxyethyl)-N-methylammonium ion. The above cations may be used alone or in combination of two or more.

[0038] From the viewpoint of the resistance of the electrophotographic belt, the content of the cations contained in the electrophotographic belt together with the content of the paired anions (the content of the ionic compound) is preferably 0.5% by mass or more relative to the total amount of the thermoplastic resin composition. There is no particular limitation on the upper limit; however, an addition amount greater than 8% by mass will limit the resistance reduction effect. In addition, from the viewpoint of good formability of the thermoplastic resin composition, a content of 8% by mass or less is preferred. In addition, as an ionic compound, blending with the thermoplastic resin composition can be performed.

[0039] <Anions>

[0040] The anion is not particularly limited as long as it can form an ionic compound by pairing with the above-mentioned cation, and examples thereof include ClO4 - Br- , Cl - 、AlCl4 - 、Al2Cl7 - 、NO3 - 、BF4 - PF6 - 、CH3COO - CF3COO - CF3SO3 - 、(CF3SO2)3C - 、AsF6 - 、SbF6 - 、F(HF)n - 、CH3CH2OSO3 - 、H2PO4 - CF3CF2CF2CF2SO3 - CF3CF2CF2COO - , and an anion represented by the following formula (1). Among them, a sulfonyl imide anion represented by the following formula (1) is preferred from the viewpoints of, for example, affinity with the polyester resin and conductivity.

[0041]

[0042] In the structural formula (1), m and n each independently represent an integer of 1 to 4.

[0043] Specific examples of the anion satisfying the structural formula (1) include bis(trifluoromethanesulfonyl)imide ion, bis(perfluoroethanesulfonyl)imide ion, bis(perfluoropropanesulfonyl)imide ion, bis(nonafluorobutanesulfonyl)imide ion, (bis(perfluorobutanesulfonyl)imide ion), trifluoromethanesulfonylperfluoropropanesulfonylimide ion, and trifluoromethanesulfonylperfluorobutanesulfonylimide ion. The above anions may be used alone or in combination of two or more.

[0044] <Compound Having At Least Two Amide Groups in One Molecule (Amide Compound)>

[0045] The molecular weight of the compound having at least two amide groups in one molecule is preferably 1000 or less, particularly 800 or less. In addition, the lower limit of the molecular weight of the amide compound is not particularly limited; however, it is preferably 200 or more. It is believed that the molecular weight of the amide compound within the above range can provide more effective interaction among the thermoplastic polyester, the ionic liquid, and the amide compound during the hot melt kneading step.

[0046] In addition, the amide compound is preferably melted at the temperature in the hot melt kneading step. The melting point is preferably 70°C or more and less than 200°C, and more preferably 100°C or more and 170°C or less. When the melting point is within the above range, the amide compound is excellent in dispersibility or distribution in the thermoplastic resin composition during the hot melt kneading step, is easily arranged between the polyester resin and the molecules of the cations and anions, and is difficult to decompose by thermal degradation. Therefore, it is easy to further improve the oozing-out suppressing effect.

[0047] Fatty acid bisamide is preferably used as the compound having at least two amide groups. Fatty acid bisamide includes a fatty acid group (preferably a long-chain fatty acid group) and an amide group in the molecule, has excellent compatibility with the thermoplastic polyester resin, and is relatively stable in terms of heat and chemical properties.

[0048] From the viewpoint of compatibility with the thermoplastic polyester resin and thermal and chemical stability, the carbon number of the long-chain fatty acid group is preferably in the range of 7 to 23. Aromatic bisamide can be used as the compound having at least two amide groups. Aromatic bisamide is a bisamide including a fatty acid group and an amide group in the molecule in which the amide group is bonded to an aromatic hydrocarbon.

[0049] Alkylenebisfatty acid amides such as ethylenebis(fatty acid amide) can be used as fatty acid bisamides. Specific examples thereof include methylenebisstearic acid amide (Tm (melting point): 142°C), ethylenebiscapric acid amide (Tm: 161°C), ethylenebislauric acid amide (Tm: 157°C), ethylenebisstearic acid amide (Tm: 145°C), ethylenebishydroxystearic acid amide (Tm: 145°C), ethylenebisbehenic acid amide (Tm: 142°C), hexamethylenebisstearic acid amide (Tm: 140°C), hexamethylenebisbehenic acid amide (Tm: 142°C), and hexamethylenebisstearic acid amide (Tm: 142°C). Methyl bishydroxystearic acid amide (Tm: 135°C), N,N'-distearyl adipamide (Tm: 141°C), N,N'-distearyl sebacic acid amide (Tm: 136°C), ethylene bisoleic acid amide (Tm: 115°C), ethylene biserucic acid amide (Tm: 120°C), hexamethylene bisoleic acid amide (Tm: 110°C), N,N'-diol adipamide (Tm: 118°C), and N,N'-diol sebacic acid amide (Tm: 113°C).

[0050] The content (mass) of the compound having at least two amide groups in one molecule is preferably 2% or more and 80% or less relative to the total content of cations and anions (mass of ionic compounds), and more preferably 5% or more and 50% or less.

[0051] When the content is 2% or more, the number of amide groups interacting with the thermoplastic polyester resin and cations and anions is large, which is preferred in order to further suppress bleeding. In addition, when it is 80% or less, it is easy to suppress the decrease in melt viscosity of the thermoplastic resin composition, thereby suppressing the decrease in strength of the electrophotographic belt. In addition, it is easy to suppress excessive decrease in mobility of cations and anions, thereby suppressing increase in resistance of the electrophotographic belt.

[0052] <Polyetheresteramide (PEEA)>

[0053] Examples of PEEA include compounds having mainly a copolymer composed of a polyamide block unit such as nylon 6, nylon 66, nylon 11, and nylon 12, and a polyetherester unit.

[0054] Examples thereof include salts derived from lactams (e.g., caprolactam, lauryl lactam) or copolymers of aminocarboxylic acids, polyethylene glycol, and dicarboxylic acids. Specific examples of the above-mentioned dicarboxylic acids include terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, undecane dioic acid, and dodecanedioic acid. PEEA can be produced by known polymerization methods such as melt polymerization. Of course, PEEA is not limited to these. In addition, PEEA can be a blend or alloy of more than two kinds. The compound having at least two amide groups in one molecule used in the present disclosure is mainly a low molecular weight compound with a molecular weight of less than 1000, and PEEA is a high molecular weight compound with a molecular weight greater than that of the above-mentioned compounds.

[0055] <Other additives>

[0056] Other components may be added to the thermoplastic resin composition as long as the effects of the present disclosure are not impaired. Examples of other components include conductive polymer compounds, antioxidants, UV absorbers, organic pigments, inorganic pigments, pH adjusters, crosslinking agents, compatibilizers, mold release agents, crosslinking agents, coupling agents, lubricants, insulating fillers, and conductive fillers. These additives may be used alone or in combination of two or more. The amount of the additive used may be appropriately set and is not particularly limited.

[0057] <Electronic Photography Belt>

[0058] Fig. 6A A perspective view showing an electrophotographic belt 500 having an endless belt shape according to one aspect of the present disclosure. Examples of layer configurations include a single-layer structure in which Fig. 6A The section of line A-A' in Figure 6B The first layer 501 shown in FIG. 5 is composed of a thermoplastic resin composition. In this case, the outer surface 500-1 of the first layer is the toner supporting surface (outer surface) of the electrophotographic belt.

[0059] In addition, another example of the layer configuration includes a stacked structure in which the cross section of line AA' is as follows: Figure 6C , there is shown a first layer 501 and a second layer 502 covering the outer peripheral surface of the first layer 501. When the second layer 502 is provided, the outer surface 500-1 of the second layer 502 is used as the toner supporting surface of the belt for electrophotography.

[0060] Examples of the second layer include a layer having excellent wear resistance, which includes a cured product of an active energy ray-curable resin. Such a second layer can be provided, for example, by coating a composition including an active energy ray-curable resin such as a photocurable resin on the outer peripheral surface of the first layer and then curing the composition.

[0061] The electrophotographic belt of the present disclosure having such a laminated structure has an effect of suppressing a decrease in the adhesion between the first layer and the second layer by suppressing the bleed-out of the cationic component at the interface between the first layer and the second layer.

[0062] In addition, a third layer (not shown) may be provided to cover the inner peripheral surface of the first layer. Examples of the third layer include a resin layer for reinforcing the first layer and a conductive layer for making the inner peripheral surface of the electrophotographic belt conductive.

[0063] The first layer having the endless belt shape can be produced, for example, by the following method.

[0064] i) A method of melt-extrude a mixture of a thermoplastic polyester resin, an ion conductive agent having a sulfonyl imide structure as an anion, and a compound having at least two amide groups in one molecule into a cylindrical shape.

[0065] ii) A method of molding pellets of a thermoplastic resin composition into an endless belt shape by using a molding method such as injection molding, stretch blow molding, or inflation molding.

[0066] Examples of the method of i) above include a downward extrusion type internal cooling mandrel method capable of controlling the inner diameter of an extruded tube with high accuracy, and a vacuum sizing method.

[0067] The method for producing an electrophotographic belt by stretch blow molding in the above ii) comprises the steps of: forming a preform of a thermoplastic resin composition; heating the preform; installing the heated preform into a mold for forming an endless belt and then flowing a gas into the mold to perform stretch blow molding; and cutting the stretched molded product obtained by stretch blow molding to obtain an endless-shaped belt.

[0068] The thickness of the first layer is preferably 40 μm or more and 500 μm or less, and particularly preferably 50 μm or more and 100 μm or less.

[0069] In order to improve the appearance of the surface of the electrophotographic belt and improve the releasability of the toner, for example, a treatment agent may be applied to the surface of the thermoplastic resin composition layer, or a surface treatment such as a grinding treatment may be performed. In addition, for example, an outermost layer may be provided on the surface of the thermoplastic resin composition layer by sputtering.

[0070] The use of the electrophotographic belt is not particularly limited, and is preferably used, for example, as an intermediate transfer belt that temporarily transfers and holds a toner image, and as a conveying transfer belt that conveys a recording material as a transfer material. In particular, it can be preferably used as an intermediate transfer belt. In addition, when the electrophotographic belt is used as an intermediate transfer belt, the surface specific resistivity of the electrophotographic belt is preferably 1×10 3 Ω / □ or more and 1×10 12 Ω / □ or less. When the surface resistivity is 1×10 3 When the surface resistivity is 1×10 12 When the value is less than Ω / □, the increase in transfer voltage can be more effectively suppressed, and the increase in size and cost of the power supply can be effectively suppressed.

[0071] <Electrophotographic image forming apparatus>

[0072] Hereinafter, an example of an electrophotographic image forming apparatus including an electrophotographic belt according to one aspect of the present disclosure as an intermediate transfer belt will be described. Figure 1 As shown in , the electrophotographic image forming apparatus has a so-called tandem type configuration in which electrophotographic stations of a plurality of colors are arranged side by side in the rotation direction of the intermediate transfer belt. In the following description, the constituent symbols of each color of yellow, magenta, cyan, and black are marked with Y, M, C, and k, respectively; however, for the same constitution, marking may be omitted.

[0073] exist Figure 1In the invention, charging devices 2Y, 2M, 2C, and 2k, exposure devices 3Y, 3M, 3C, and 3k, developing devices 4Y, 4M, 4C, and 4k, and an intermediate transfer belt (intermediate transfer body) 6 are arranged around photosensitive drums (photosensitive members, image carriers) 1Y, 1M, 1C, and 1k. The photosensitive drum 1 is driven to rotate in the direction of arrow F at a predetermined circumferential speed (process speed). The charging device 2 charges the peripheral surface of the photosensitive drum 1 to a predetermined polarity and potential (primary charging). The laser beam scanner as the exposure device 3 outputs laser light modulated on / off in response to image information input from an external device such as an image scanner or a computer (not shown), thereby scanning and exposing the charged surface on the photosensitive drum 1. This scanning exposure forms an electrostatic latent image corresponding to the target image information on the surface of the photosensitive drum 1.

[0074] The developing devices 4Y, 4M, 4C, and 4k contain toners of the respective color components of yellow (Y), magenta (M), cyan (C), and black (k), respectively. The developing device 4 to be used is selected based on the image information, the developer (toner) is developed on the surface of the photosensitive drum 1, and the electrostatic latent image is visualized as a toner image. The present embodiment uses a reverse development method in which the toner is attached to the exposure portion of the electrostatic latent image to develop the image. In addition, such a charging device, an exposure device, and a developing device constitute an electrophotographic image forming unit.

[0075] In addition, the intermediate transfer belt 6 is composed of an electrophotographic belt having an annular shape. The intermediate transfer belt 6 is stretched by a plurality of rollers 20, 21, and 22 so that its outer peripheral surface contacts the surface of the photosensitive drum 1. In the present embodiment, the roller 20 is a tension roller for controlling the tension of the intermediate transfer belt 6 to be constant, the roller 22 is a driving roller of the intermediate transfer belt 6, and the roller 21 is a counter roller for secondary transfer. The intermediate transfer belt 6 is rotated in the direction of the arrow G by the drive of the roller 22. In addition, each of the primary transfer rollers 5Y, 5M, 5C, and 5k is arranged at a primary transfer position facing the photosensitive drum 1 with the intermediate transfer belt 6 interposed therebetween.

[0076] By applying a primary transfer bias voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roller 5 by a constant voltage source or a constant current source (not shown), the unfixed toner images of the respective colors formed on the photosensitive drum 1 are sequentially and electrostatically primary transferred onto the intermediate transfer belt 6. Then, a full-color image is obtained in which the four colors of the unfixed toner images are superimposed on the intermediate transfer belt 6. In this way, the intermediate transfer belt 6 rotates while carrying the toner images transferred from the photosensitive drum 1. At each rotation of the photosensitive drum 1 that has been primary transferred, the surface of the photosensitive drum 1 is cleaned by removing the transfer residual toner by the cleaning device 11, and the image forming step is repeated.

[0077] In addition, at the secondary transfer position of the intermediate transfer belt 6 facing the conveying path of the recording material 7 as the transfer medium, the secondary transfer roller (transfer portion) 9 is arranged in pressure contact on the toner image supporting surface side of the intermediate transfer belt 6. In addition, on the back side of the intermediate transfer belt 6 at the secondary transfer position, an opposing roller 21 serving as an opposing electrode of the secondary transfer roller 9 and having a bias applied thereto is arranged. When the toner image on the intermediate transfer belt 6 is transferred onto the recording material 7, a bias of the same polarity as the toner, such as -1000 to -3000V, is applied to the opposing roller 21 by a transfer bias applying device 28, and then a current of -10 to 50μA flows. The transfer voltage is detected by a transfer voltage detecting device 29. In addition, on the downstream side of the secondary transfer position, a cleaning device (belt cleaner) 12 for removing the toner remaining on the intermediate transfer belt 6 after the secondary transfer is provided.

[0078] The recording material 7 passes through the conveying guide 8 and is conveyed in the direction of the arrow H, and is introduced at the secondary transfer position. The recording material 7 introduced at the secondary transfer position is held and conveyed to the secondary transfer position, and a constant voltage bias (transfer bias) controlled to a predetermined value is applied to the counter roller 21 of the secondary transfer roller 9 by the secondary transfer bias applying device 28. A transfer bias having the same polarity as the toner is applied to the counter roller 21, and a four-color full-color image (toner image) superimposed on the intermediate transfer belt 6 at the transfer site is collectively transferred onto the recording material 7, thereby forming a full-color unfixed toner image on the recording material. The recording material 7 to which the toner image is transferred is introduced into a fixer (not shown) and fixed by heating.

[0079] One aspect of the present disclosure can provide an electrophotographic belt, wherein after long-term repeated image output, during long-term storage, the surface state of the belt hardly changes from the initial state. In addition, another aspect of the present disclosure can provide an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

[0080] [Example]

[0081] Embodiments and comparative examples will be shown below, and an electrophotographic belt and an electrophotographic image forming apparatus according to the present disclosure will be specifically described.The electrophotographic belt and the electrophotographic image forming apparatus according to the present disclosure are not limited to the configurations embodied in the embodiments.

[0082] Materials described in Tables 1 to 5 below were prepared as materials (thermoplastic polyester resin, ionic compound having cations and anions, amide compound, polyether ester amide, and silicone particles) for producing electrophotographic belts according to Examples and Comparative Examples.

[0083] The cations in the ionic compounds 1 to 6 shown in Table 2 correspond to the cations having a hydroxyl group, but the cation in the ionic compound 7 does not correspond to the cation having a hydroxyl group. In addition, the amide compounds 1 and 2 shown in Table 3 correspond to compounds having at least two amide groups in one molecule, but the amide compound 3 does not correspond to the compound.

[0084] Table 1 <Thermoplastic polyester resin>

[0085]

[0086] Table 2 <Ionic compounds having cations and anions>

[0087]

[0088] Table 3 <Amide compounds>

[0089]

[0090] The structure of ethylene bisstearic acid amide (molecular weight = 593) is shown below.

[0091]

[0092] The structure of ethylenebiscapric acid amide (molecular weight = 369) is shown below.

[0093]

[0094] The structure of stearic acid amide (molecular weight = 284) is shown below.

[0095]

[0096] Table 4 <Polyetheresteramide (PEEA)>

[0097]

[0098] Table 5 <Silicone particles>

[0099]

[0100] (Methods for measuring and evaluating characteristic values)

[0101] Evaluation methods (1) to (4) of the electrophotographic belt according to the examples and comparative examples will be described below. In the following evaluation, A4 size paper having an Ra (arithmetic mean roughness) of 4 and an Rzjis (10-point average roughness) of 15 obtained by leaving it in an environment at a temperature of 23° C. and a relative humidity of 45% for 1 day was used as a transfer medium for image formation.

[0102] (1) Surface resistivity

[0103] The surface specific resistivity of the electrophotographic belt was measured based on the method specified in Japanese Industrial Standard (JIS)-K6911 1995. A probe (trade name: UR-100) having a main electrode with an inner diameter of 50 mm, a guard ring electrode with an inner diameter of 53.2 mm, and an outer diameter of 57.2 mm with a high resistance meter (trade name: Hiresta UP MCP-HT450 model) was used as a measuring device. The high resistance meter and the probe were manufactured by Mitsubishi Chemical Analytech Co., Ltd.

[0104] The produced electrophotographic belt was placed in an environmental test chamber controlled at a temperature of 23°C and a relative humidity of 50% for 12 hours. Thereafter, a voltage of 250V was applied to the electrophotographic belt to be measured for 10 seconds under an environment of a temperature of 23°C and a relative humidity of 50%, and the surface intrinsic resistivity of the electrophotographic belt at four points in the circumferential direction was measured. The average value (ρs) of the obtained surface intrinsic resistivity was defined as logρs based on the logarithm of 10 and used as an index of resistance. The values ​​shown in the "Surface Intrinsic Resistivity" column of Tables 6 to 8 are the values ​​of this logρs.

[0105] (2) Initial toner transfer efficiency

[0106] The produced electrophotographic belt was mounted as an intermediate transfer belt to a drum cartridge of a full-color electrophotographic apparatus (trade name: LBP-5200, manufactured by Canon Inc.) Using the full-color electrophotographic apparatus, cyan toner and magenta toner were superimposed on a transfer medium to form a solid purple image.

[0107] The toner transfer efficiency is calculated from the amount F (g) of toner remaining on the surface of the electrophotographic belt by primary transfer from the photosensitive drum and the amount S (g) of residual toner remaining on the surface of the electrophotographic belt when the toner is secondarily transferred to the transfer medium. Specifically, it is expressed by the following formula [1].

[0108] Toner transfer efficiency (%) = (1-S / F) × 100 [1]

[0109] (3) Toner transfer efficiency after durability test

[0110] For the image formed on the 300,000th transfer medium, the toner transfer efficiency was measured by the same method as in (2).

[0111] (4) Toner transfer efficiency of the electrophotographic belt after 10 days of durability test

[0112] The electrophotographic belt subjected to the durability test in (3) was stored in a full-color electrophotographic apparatus at a controlled temperature of 23° C. and a relative humidity of 50% for 10 days, and then a cyan toner and a magenta toner were superimposed on a transfer medium to form a solid purple image. For the image formed on the transfer medium, the toner transfer efficiency was measured by the same method as in (2).

[0113] [Examples 1 to 10]

[0114] The materials were pre-blended according to the formulation shown in Table 6, and then heat-melt kneaded by using a twin-screw extruder (trade name: TEX44α, manufactured by The Japan Steel Works, Ltd.) to prepare a pelletized thermoplastic resin composition. The temperature of the heat-melt kneading step was adjusted to a range of 270° C. or more and 300° C. or less, and the time of the heat-melt kneading step was set to about 3 minutes.

[0115] The obtained pelletized thermoplastic resin composition was dried at 140°C for 6 hours. Figure 2 In the hopper 48 of an injection molding apparatus (trade name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.) having the configuration shown in FIG.

[0116] The set temperature of the barrel is set to 290° C., the above composition is melted in the screws 42 and 42A, and injection molded into a mold (not shown) through the nozzle 41A to prepare a preform 104 (refer to Figure 3 ). The temperature of the mold for injection molding was 30°C.

[0117] Thereafter, the preform 104 is placed in Figure 3 In the primary blow molding apparatus shown in FIG. 1 , a heating device 107 having a temperature of 500° C. is placed in the blow molding apparatus 107 to soften the preform 104, and the preform 104 is heated at 500° C. In a blow mold 108 whose mold temperature is maintained at room temperature, a blow molding is performed by using the force of a stretch rod 109 and air (blow injection portion 110) at a preform temperature of 160° C., an air pressure of 0.3 MPa, and a stretch rod speed of 1000 mm / s to obtain a blow molded bottle 112.

[0118] Thereafter, the obtained blow molded bottle 205 is placed in a Figure 4The nickel cylindrical mold 201 produced by electroforming in the secondary blow molding apparatus shown in the figure is placed in the mold, and the outer mold 203 is installed. An air pressure of 0.1 MPa is applied to the blow-molded bottle 205, and the air is adjusted so as not to leak to the outside, thereby transferring the blow-molded bottle 205 to the inner surface of the mold, and the nickel cylindrical mold 201 is uniformly heated at 190° C. for a total of 60 seconds by the heater 202 while rotating.

[0119] Thereafter, air was blown onto the nickel cylindrical mold to cool it to room temperature, the pressure applied to the inside of the blow-molded bottle was released, and a blow-molded bottle with improved size was obtained by annealing. An endless belt was obtained by cutting both ends of the blow-molded bottle. The endless belt was used as an electrophotographic belt. The thickness of the electrophotographic belt was 70 μm. Table 6 shows the results of evaluations (1) to (4) of the electrophotographic belt.

[0120] Table 6 <Examples 1 to 10>

[0121]

[0122] [Examples 11 to 15]

[0123] An endless belt was obtained in the same manner as in Example 1 except that the formulation shown in Table 7 was used. This endless belt was used as a base layer, and in order to improve the adhesion with other contact members such as a photosensitive drum and a cleaning blade and the releasability of the toner, an outermost layer composed of an acrylic resin as an active energy ray-curable resin was provided as follows.

[0124] The following materials as raw materials for the outermost layer of acrylic resin were mixed.

[0125] ·Dipentaerythritol hexaacrylate 100 parts by mass

[0126] (Trade name: Light acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.)

[0127] Carbon black (Ketchen black) 15 parts by mass

[0128] (Trade name: MHI Black #273, manufactured by Mikuni Color Co., Ltd.)

[0129] · Photopolymerization initiator 5 parts by mass

[0130] (Trade name: Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.)

[0131] The mixture is diluted with methyl ethyl ketone so that the resin solid content becomes 6% by mass, and stirred with a stirrer to obtain a uniformly mixed solution for forming the outermost layer of the acrylic resin. The mixed solution is uniformly applied to the peripheral surface of the above-mentioned base layer by a spray method, dried at 60°C for one minute to remove the solvent, and then irradiated with ultraviolet rays to cure it. This provides an electronic photography belt having an outermost layer of an acrylic resin with a thickness of 2 μm formed on the outer peripheral surface of the base layer. Use an ultraviolet irradiation device (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) as an ultraviolet source to irradiate with ultraviolet rays until the cumulative light amount reaches 1000 mJ / cm 2 Table 7 shows the results of evaluations (1) to (4) of the obtained electrophotographic belt.

[0132] Table 7 <Examples 11 to 15>

[0133]

[0134] As shown in Tables 6 and 7, in all the material compositions of Examples 1 to 15, in the evaluation of the toner transfer efficiency of the electrophotographic belt, the toner transfer efficiency after standing for 10 days after the durability test was 92%, indicating a good result.

[0135] [Comparative Examples 1 to 7]

[0136] A belt for electrophotography was produced in the same manner as in Example 1 or Example 11 except that the kinds of materials and the blending amounts were as shown in Table 8 below.

[0137] Table 8 <Comparative Examples 1 to 7>

[0138]

[0139] In Comparative Examples 1, 2, and 3, a cation containing no hydroxyl group (ionic compound 7) was included. In Comparative Examples 1 and 4, no amide compound was included. In Comparative Examples 5, 6, and 7, a compound having one amide group was included instead of a compound having at least two amide groups in one molecule. In Comparative Example 7, an outermost layer composed of an acrylic resin was provided.

[0140] In any of the comparative examples, the toner transfer efficiency after leaving for 10 days after the durability test was lower than the initial toner transfer efficiency and the toner transfer efficiency after the durability test by 10% or more. This result confirms that, except for the combination of the cation and the compound having an amide group specified in the present disclosure, the affinity due to the interaction between the thermoplastic polyester resin and the cation was not improved, and the effect of suppressing the adhesion of the exudate on the belt surface was not obtained.

[0141] While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An electrophotographic belt, characterized in that: It includes: a first layer, the first layer comprising a thermoplastic resin composition, The thermoplastic resin composition comprises: Thermoplastic polyester resin; a cation having a hydroxyl group; anions; and An amide compound having at least two amide groups in one molecule. 2 . The electrophotographic belt according to claim 1 , wherein the molecular weight of the amide compound is 1,000 or less. 3 . The electrophotographic belt according to claim 1 , wherein the cation has two or more hydroxyl groups in one molecule.

4. The electrophotographic belt according to claim 1, wherein the cation is at least one cation selected from the group consisting of ammonium ions, imidazolium ions, pyridinium ions, piperidinium ions, pyrrolidinium ions, and phosphonium ions.

5. The electrophotographic belt according to claim 1, wherein the anion has a structure represented by the following formula (1): wherein m and n each independently represent an integer of 1 to 4. 6 . The electrophotographic belt according to claim 1 , wherein the thermoplastic polyester resin comprises at least one selected from the group consisting of polyalkylene terephthalates and polyalkylene naphthalates.

7. The electrophotographic belt according to claim 6, wherein the polyalkylene terephthalate is polyethylene terephthalate.

8. The electrophotographic belt according to claim 6, wherein the polyalkylene naphthalate is polyethylene naphthalate.

9. The electrophotographic belt according to claim 1, wherein the amide compound is fatty acid bisamide and / or aromatic bisamide.

10. The electrophotographic belt according to claim 9, wherein the fatty acid bisamide is ethylenebis(fatty acid amide). 11 . The electrophotographic belt according to claim 1 , wherein an amount of the ionic compound having the cation and the anion is 0.5% by mass or more and 8% by mass or less relative to a total amount of the thermoplastic resin composition. 12 . The electrophotographic belt according to claim 1 , wherein the mass of the compound having at least two amide groups in one molecule is 2% or more and 80% or less relative to the mass of the ionic compound having the cation and the anion. 13 . The electrophotographic belt according to claim 1 , wherein the thermoplastic resin composition further comprises polyetheresteramide. 14 . The electrophotographic belt according to claim 1 , further comprising a second layer comprising a cured product of a composition containing an active energy ray-curable resin.

15. The electrophotographic belt according to claim 1, wherein the electrophotographic belt has an endless belt shape.

16. The electrophotographic belt according to claim 1, which has an endless shape and further comprises a second layer covering an outer peripheral surface of the first layer, wherein the second layer comprises a cured product of a composition containing an active energy ray-curable resin.

17. An electrophotographic image forming apparatus, characterized in that: It includes an intermediate transfer belt, The intermediate transfer belt is composed of the electrophotographic belt according to any one of claims 1 to 16.

18. A method for producing an electrophotographic belt, characterized in that: The electrophotographic belt has an endless belt shape and is provided with a first layer including a thermoplastic resin composition, and the method comprises the following steps: (i) hot melt kneading a thermoplastic polyester resin, an ionic compound including a cation and an anion having a hydroxyl group, and an amide compound having at least two amide groups in one molecule to form the thermoplastic resin composition; and (ii) forming the thermoplastic resin composition into an endless belt shape. 19 . The method according to claim 18 , comprising melt-extruding the thermoplastic polyester resin, the ionic compound, and the amide compound into a cylindrical shape.

20. The method according to claim 18, comprising the step of molding the thermoplastic resin composition into an endless belt shape by injection molding, stretch blow molding, or inflation molding.

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