JP2018189882A - Electrophotographic belt, method for manufacturing the same, and electrophotographic apparatus - Google Patents

Abstract

An electrophotographic belt that includes a conductive layer having high conductivity, suppresses the occurrence of cracking of the conductive layer over a long period of time, and can be used stably for forming an electrophotographic image. An electrophotographic belt having at least a base layer and a conductive layer, the conductive layer containing an acrylic resin as a binder, carbon black, and a polyether ester amide, The polyether group has a hydroxyl value of 20 to 120 mgKOH / g, and the carbon black content in the conductive layer is 10 to 18 parts by mass with respect to 100 parts by mass of the acrylic resin in the conductive layer. In the infrared absorption spectrum of an amide, the intensity when the absorbance of the C—O bond derived from the ether group is A, the absorbance of the C═O bond derived from the amide group is B, and the absorbance of the C═O bond derived from the ester group is C. An electrophotographic belt having a ratio [A / (A + B + C)] of 0.05 to 0.43. [Selection] Figure 1

Description

  The present invention relates to an electrophotographic belt used in an electrophotographic image forming apparatus (hereinafter referred to as “electrophotographic apparatus”) such as a copying machine or a printer, a manufacturing method thereof, and an electrophotographic apparatus.

  In an electrophotographic apparatus, an electrostatic charge image carrier such as a photosensitive drum is charged, and the charged electrostatic charge image carrier is exposed to form an electrostatic latent image. Thereafter, the electrostatic latent image is developed with the frictionally charged toner, and the toner image is transferred and fixed to a recording medium such as paper, whereby a desired image is formed on the recording medium.

  As a transfer method of an electrophotographic apparatus, an unfixed toner image on an electrostatic charge image carrier such as a photosensitive drum is primarily transferred to an intermediate transfer member by a current supplied from a transfer power source, and then the unfixed toner image is transferred. An intermediate transfer method is used in which the image is secondarily transferred from the intermediate transfer member to the recording medium. As the transfer power source, a power source for primary transfer and a power source for secondary transfer are respectively provided. In each transfer process, an optimum current value is selected according to the surrounding environment (temperature and humidity) and the type of recording medium. It is controlled to become. Such an intermediate transfer method is particularly employed in color electrophotographic apparatuses. In a color electrophotographic apparatus, toners of four colors (yellow, magenta, cyan, and black) are sequentially transferred from an image forming portion of each color onto an intermediate transfer member, and the resultant composite image is collectively transferred to a recording medium. Therefore, there are advantages that the printing speed can be increased and a high-quality image can be obtained.

  In recent years, as the need for miniaturization and cost reduction of copiers and printers increases, it has been studied to reduce the number of parts. Specifically, by using a common power source for primary transfer and secondary transfer, and using an intermediate transfer member having higher conductivity than the conventional one, current flows in a circumferential direction from one transfer power source through the intermediate transfer member. A method of performing the primary transfer by using the above method is being studied.

  Here, as a method of increasing the circumferential conductivity of the intermediate transfer member, a method of adding carbon black or an ionic conductive agent, or a method of using them together is known. Patent Document 1 discloses an intermediate transfer belt in which conductivity is controlled by adding carbon black and polyetheresteramide, which is one of ionic conductive agents, to a thermoplastic resin. As a specific configuration, an intermediate transfer belt containing carbon black and polyetheresteramide in a polyvinylidene fluoride resin having a thickness of 100 μm is described.

JP 2005-164673 A

  The inventors of the present invention have studied to increase the amount of carbon black in the resin in order to further improve the conductivity of the intermediate transfer belt disclosed in Patent Document 1. However, the intermediate transfer belt containing a large amount of carbon black has insufficient strength and may be easily cracked. Therefore, in order to obtain an intermediate transfer belt having a highly conductive layer that can be suitably used in a miniaturized and low-cost electrophotographic apparatus, the conductivity can be increased by a method other than increasing the amount of carbon black in the conductive layer. The present inventors have recognized that the development of technology that can be improved is necessary.

  Therefore, one embodiment of the present invention provides an electrophotographic belt that includes a conductive layer having high conductivity, can suppress the occurrence of cracks in the conductive layer over a long period of time, and can be used for forming an electrophotographic image stably. It is aimed at. Another aspect of the present invention is directed to providing an electrophotographic apparatus that can be further reduced in cost and size.

  According to one embodiment of the present invention, an electrophotographic belt having at least a base layer and a conductive layer, the conductive layer containing an acrylic resin as a binder, carbon black, and polyetheresteramide. The hydroxyl value of the acrylic resin is 20 mgKOH / g or more and 120 mgKOH / g or less, and the content of the carbon black in the conductive layer is 10 parts by mass with respect to 100 parts by mass of the acrylic resin in the conductive layer. The absorbance of the C—O bond derived from the ether group in the infrared absorption spectrum of the polyether ester amide is A, the absorbance of the C═O bond derived from the amide group is B, and derived from the ester group. The intensity ratio [A / (A + B + C)] where C = O bond absorbance of C is C is 0.05 or more and 0.43 or less. True for the belt is provided.

  Further, according to one aspect of the present invention, there is provided a method for producing an electrophotographic belt according to the present invention, the raw material monomer for the acrylic resin, a solvent for dissolving the raw material monomer, the carbon black, and the polyether ester amide. A method for producing an electrophotographic belt comprising the step of forming a conductive layer by curing a coating film of a conductive layer-forming coating material comprising:

  According to another aspect of the present invention, there is provided an electrophotographic apparatus comprising the electrophotographic belt according to the present invention as an intermediate transfer belt.

  According to another aspect of the present invention, a photosensitive drum for forming a toner image, an intermediate transfer belt on which the toner image is primarily transferred in contact with the photosensitive drum, and the intermediate transfer belt facing the intermediate transfer belt for recording An electrophotographic apparatus comprising: a secondary transfer member for secondary transfer of the toner image to a medium; and a power source capable of applying a secondary transfer voltage to the secondary transfer member, wherein the intermediate transfer belt includes: In the electrophotographic belt according to the present invention, the power source applies a voltage to the secondary transfer member to cause a current to flow from the secondary transfer member to the photosensitive drum via the intermediate transfer belt, An electrophotographic apparatus is provided, wherein the toner image is primarily transferred from the photosensitive drum to the intermediate transfer belt.

  According to one embodiment of the present invention, there is provided an electrophotographic belt that includes a conductive layer having high conductivity, suppresses the occurrence of cracking of the conductive layer over a long period of time, and can be used stably for forming an electrophotographic image. can do. In addition, according to another aspect of the present invention, an electrophotographic apparatus that can achieve further cost reduction and size reduction can be provided.

1 is a schematic view of an electrophotographic belt according to an embodiment of the present invention. It is the schematic of the belt for electrophotography which concerns on other embodiment of this invention. 1 is a schematic diagram of an electrophotographic apparatus according to an embodiment of the present invention. FIG. 4 is an enlarged schematic diagram of an image forming unit 205a in FIG. 3. It is a figure which shows an example of the infrared absorption spectrum of the polyetheresteramide contained in the electroconductive layer of the electrophotographic transfer belt which concerns on this embodiment.

<Electrophotographic belt>
The electrophotographic belt according to one embodiment of the present invention includes a base layer and a conductive layer. The conductive layer contains an acrylic resin as a binder, carbon black, and polyetheresteramide. The hydroxyl value of the acrylic resin is 20 mgKOH / g or more and 120 mgKOH / g or less. The content of the carbon black in the conductive layer is 10 parts by mass or more and 18 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer. In the infrared absorption spectrum of the polyether ester amide, A represents the absorbance of the C—O bond derived from the ether group, B represents the absorbance of the C═O bond derived from the amide group, and C represents the absorbance of the C═O bond derived from the ester group. To do. In this case, the intensity ratio [A / (A + B + C)] (hereinafter also referred to as IR intensity ratio) is 0.05 or more and 0.43 or less.

  The present inventors have intensively studied a method for improving the conductivity of the conductive layer of the electrophotographic belt without depending on the increase in the amount of carbon black. By the way, the conductive agent includes an electronic conductive agent such as carbon black and an ionic conductive agent such as polyetheresteramide. Here, when a large amount of polyetheresteramide is contained in the conductive layer, the ratio of the binder in the conductive layer is relatively reduced, and therefore the mechanical properties of the conductive layer may be deteriorated. Therefore, the content naturally has an upper limit. Considering this point, it is considered that the conductivity that can be imparted to the conductive layer by the polyether ester amide is lower than the conductivity that can be imparted by an electronic conductive agent such as carbon black.

  However, as a result of the study by the present inventors, a specific polyetheresteramide has a limited conductivity imparting ability when used alone as a conductive agent, but it is high in a conductive layer when used in combination with carbon black. It has been found that conductivity can be imparted. The conductivity exceeds that which can be imparted by carbon black alone. The specific polyetheresteramide has an IR intensity ratio in the range of 0.05 to 0.43.

  The conductivity improving effect exhibited by the combination of the specific polyetheresteramide and carbon black is obtained by the combination of the polyetheresteramide and carbon black whose IR intensity ratio is outside the range. Absent. Therefore, this combination is considered unique. In the present invention, the specific polyetheresteramide is used together with an acrylic resin having a hydroxyl value within a specific range and a specific amount of carbon black with respect to the acrylic resin. Accordingly, it is possible to provide an electrophotographic belt that includes a conductive layer having high conductivity, suppresses the occurrence of cracking of the conductive layer over a long period of time, and can stably form an electrophotographic image. Can do.

The electrophotographic belt according to one embodiment of the present invention will be described below with reference to the drawings.
FIG. 1A is a perspective view of an electrophotographic belt 100 having an endless belt shape according to an embodiment of the present invention. FIG.1 (b) is an enlarged view of the axial cross section of Fig.1 (a). In the electrophotographic belt 100 shown in FIG. 1, the conductive layer 102 exists on the inner peripheral surface of the base layer 101, and the entire conductive layer 102 is exposed on the inner peripheral surface of the electrophotographic belt.
FIG. 2A is a perspective view of an electrophotographic belt 100 having an endless belt shape according to another embodiment of the present invention. FIG.2 (b) is an enlarged view of the axial cross section of Fig.2 (a). In the electrophotographic belt 100 shown in FIG. 2, the conductive layer 102 exists on the outer peripheral surface of the base layer 101. On the conductive layer 102, an outermost layer 103 is provided in contact with the photosensitive drum and other members. Although the outermost layer 103 is an arbitrary layer, when the outermost layer 103 is provided as shown in FIG. 2, the outermost layer 103 is not provided on the entire surface in the axial direction of the electrophotographic belt, but only on the image forming region. preferable. That is, it is preferable that a part of the conductive layer 102 is exposed on the surface (outer peripheral surface) of the electrophotographic belt in the non-image forming region, and the exposed portion 104 of the conductive layer is formed. Although not shown, a conductive layer may be provided on both the inner and outer peripheral surfaces of the electrophotographic belt.

  Thus, it is preferable that all or part of the conductive layer is exposed on the outer peripheral surface or inner peripheral surface of the electrophotographic belt. By connecting a constant voltage element such as a Zener diode to the exposed portion of the conductive layer 102 in FIGS. 1 and 2 via a member that contacts the exposed portion, the potential of the conductive layer can be made constant. It becomes possible. As a result, a desired current can be supplied to all the photosensitive drums through the conductive layer, and not only the secondary transfer but also the primary transfer can be performed with one transfer power source. Details will be described later.

  The endless belt shape refers to, for example, a shape obtained by joining a sheet or film-like molded product in a cylindrical shape, and refers to a shape that can be stretched and rotated by a plurality of rollers. Among endless belt shapes, a seamless shape having no seam is preferable from the viewpoint of reducing uneven thickness of the belt.

Next, the constituent materials and forming method of each layer of the electrophotographic belt will be described in detail.
[Base layer]
The base layer has an endless belt shape. Specifically, the base layer includes a semi-conductive material containing a conductive agent in a resin, a film in which films are connected in a cylindrical shape, or a cylindrical seamless belt.

(resin)
As the resin, any of a thermoplastic resin and a thermosetting resin can be used. Examples of the thermoplastic resin include the following. Polycarbonate, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polymethylpentene-1, polystyrene, polyamide, polylactic acid (PLLA), polysulfone, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, Polyphenylene sulfide, polyether sulfone, polyether nitrile, thermoplastic polyimide, polyether ether ketone, thermotropic liquid crystal polymer, polyamic acid and the like. Moreover, as a thermosetting resin, the following are mentioned, for example. Thermosetting polyimide, phenol resin, polyester resin, amino resin, epoxy resin, melamine resin, thermosetting polyurethane resin, thermosetting acrylic resin, fluorine-modified resin, etc. One of these may be used alone, or two or more may be used as a blended and alloyed mixture.

(Conductive agent)
In the base layer, an electron conductive material, an ion conductive material, or the like can be used as a conductive agent. As the electron conductive substance, conductive polymers such as carbon black, antimony-doped tin oxide, titanium oxide, polyaniline, polypyrrole, and polythiophene can be used. As the ion conductive substance, sodium perchlorate, lithium, cationic or anionic ionic surfactants, nonionic surfactants, ionic liquids, oligomers or polymer compounds having oxyalkylene repeating units can be used. It is. In the base layer, additives such as an antioxidant, an ultraviolet absorber, a pH adjuster, a crosslinking agent, a pigment, and an elastomer can be added as necessary.

(Formation method of base layer)
The base layer can be formed, for example, by the following method. When a thermosetting resin such as polyimide is used as the resin, carbon black as a conductive agent is dispersed as a varnish together with a polyimide precursor or a soluble polyimide and a solvent. Then, it coats using apparatuses, such as centrifugal molding, and can shape | mold as a seamless belt through a baking process. The thickness of the base layer is preferably 10 μm or more and 500 μm or less, and more preferably 30 μm or more and 150 μm or less.

  When a thermoplastic resin is used as the resin, carbon black, which is a conductive agent, resin, and additives as necessary are mixed, melted and kneaded using a biaxial kneader, etc. Conductive pellets are produced. Next, a semiconductive film can be obtained by extruding the pellets into a sheet shape, a film shape or a seamless belt shape by melt extrusion. Moreover, it can also shape | mold by hot press and injection molding, and a semiconductive film can also be obtained by extending-blowing the preform formed.

As the electric resistance of the base layer thus obtained, the volume resistivity when 250 V is applied is preferably 1.0 × 10 ⁸ Ω · cm or more and 1.0 × 10 ¹² Ω · cm or less. The surface resistivity is preferably 1.0 × 10 ⁸ Ω / □ or more and 1.0 × 10 ¹² Ω / □ or less. By controlling the electrical resistance within these semiconductive regions, it is possible to suppress transfer image defects due to insufficient transfer voltage in a low-humidity environment or due to charge-up during continuous driving.

[Conductive layer]
The conductive layer contains an acrylic resin as a binder, carbon black, and polyether ester amide. The surface resistivity of the conductive layer when 10 V is applied is preferably 1.0 × 10 ⁷ Ω / □ or less, more preferably 5.0 × 10 ⁶ Ω / □ or less, and 3.0 × 10. More preferably, it is ⁶ Ω / □ or less. The lower limit of the surface resistivity is not particularly limited. When the surface resistivity is within this range, a primary transfer current equivalent to the conventional primary transfer having a plurality of transfer power sources can be supplied to each photosensitive drum. In addition, this surface resistivity is a value measured by the measuring method of the surface resistivity of the electroconductive layer mentioned later. The thickness of the conductive layer is preferably 0.05 μm or more and 20 μm or less, and more preferably 0.1 or more and 5 μm or less from the viewpoint of bending resistance.

  The conductive layer preferably has an average hardness of 0.10 GPa or more in a region of 10 to 20% in the thickness (film thickness) direction from the outermost surface in a nanoindenter measurement method using a Barkovic indenter. A region less than 10% of the thickness of the conductive layer near the outermost surface is easily affected by the measurement environment such as indenter vibration. Further, the region exceeding 20% of the thickness of the conductive layer is easily affected by the base layer. Therefore, excluding these regions, the average hardness in a region of 10 to 20% of the thickness of the conductive layer is calculated. By setting the hardness of the conductive layer to 0.10 GPa or more as the average hardness in the region, wear or wear due to rubbing with other sliding members (for example, a transfer roller or a cleaning blade) mounted on the electrophotographic apparatus. The occurrence of such physical deterioration can be suppressed. The upper limit value of the average hardness in the region of the conductive layer is not particularly limited, but being 0.50 GPa or less can suppress physical damage to a sliding member mounted on a general electrophotographic apparatus. Therefore, it is preferable. That is, the average hardness in the region of the conductive layer is more preferably 0.10 GPa or more and 0.50 GPa or less. The average hardness is more preferably 0.11 GPa or more and 0.40 GPa or less, and particularly preferably 0.12 GPa or more and 0.30 GPa or less.

(acrylic resin)
Examples of the acrylic resin as a binder used in the conductive layer include thermosetting or photocurable (hereinafter referred to as reactive) acrylic resins. In consideration of the thickness of the conductive layer, the acrylic resin or the acrylic resin raw material is preferably one that can be dissolved in a solvent to form a thin layer containing the acrylic resin or a thin layer containing the acrylic resin raw material. As the said acrylic resin raw material, the monomer which has a reactive (meth) acryloyl group is mentioned, for example. The “(meth) acryloyl group” means an acryloyl group or a methacryloyl group.

  Examples of the monomer having a (meth) acryloyl group include a polyfunctional (meth) acrylic monomer. Specific examples include tri (meth) acrylate of ethoxylated isocyanuric acid, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (Meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 9,9-bis [4- ( 2-acryloyloxyethoxy) phenyl] fluorene, trimethylolpropane tri (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditri Tyrolpropane tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meta) ) Acrylate and dipentaerythritol poly (meth) acrylate. These may use 1 type and may use 2 or more types together. Note that “(meth) acryl” means acryl or methacryl, and “(meth) acrylate” means acrylate or metallate.

  Since the monomer having reactivity is affected by oxygen and water in the air during the curing reaction, not a few unreacted substances remain when the cured film is formed. After separating these from the conductive layer by an appropriate means such as solvent extraction, the raw material monomer can be identified from the cured film by using pyrolysis GC / MS, IR, NMR, elemental analysis, or the like.

  In addition to the acrylic resin, the conductive layer may contain other resins as long as the effects of the present invention are not impaired. Other resin may be used individually by 1 type, and may use 2 or more types together.

The hydroxyl value of the acrylic resin is 20 mgKOH / g or more and 120 mgKOH / g or less. The hydroxyl value is preferably 25 mgKOH / g or more and 80 mgKOH / g or less, and more preferably 30 mgKOH / g or more and 60 mgKOH / g or less.
When the hydroxyl value is less than 20 mgKOH / g, the acrylic resin cannot be compatible with the polyether ester amide in the conductive layer forming paint, and a uniform conductive layer forming paint cannot be obtained. In addition, when the hydroxyl value exceeds 120 mgKOH / g, the acrylic resin is completely dissolved in the polyether ester amide in the conductive layer forming paint containing the polyether ester amide. In this case, it is not possible to express higher conductivity exceeding the conductivity exhibited by the conductive layer containing carbon black as the only conductive agent, which is the effect of the present invention. Although details will be described in Examples, it is presumed that having an appropriate compatibility contributes to the effect. The hydroxyl value referred to here is an anhydrous acetic acid (acetylation reagent) weighed in a certain amount and acetylated in the acrylic resin, which is an object weighed in advance, and not used for acetylation. It can be determined by titrating acetic acid with a potassium hydroxide solution. At this time, the amount of hydroxyl group contained in 1 g of the object to be measured is expressed in mg of potassium hydroxide required for titration. A detailed method for measuring the hydroxyl value will be described later. Although the hydroxyl value of the acrylic resin is described here, the hydroxyl value of the acrylic resin raw material monomer is preferably within the range of the hydroxyl value of the acrylic resin. This is because the hydroxyl value does not change before and after polymerization. When there are a plurality of raw material monomers for the acrylic resin, the hydroxyl value of the monomer refers to the hydroxyl value of a mixture of the plurality of monomers.

(Carbon black)
Although it does not specifically limit as carbon black, Ketjen black (trademark), acetylene black, etc. are mentioned. Among these, ketjen black (registered trademark) having high conductivity is preferable. From the viewpoint of the surface resistivity, the content of carbon black in the conductive layer is 10 parts by mass or more with respect to 100 parts by mass of the acrylic resin in the conductive layer. In addition, from the viewpoint of suppressing physical deterioration such as cracking and wear due to rubbing with other sliding members (for example, transfer rollers and stretching rollers), the content of carbon black in the conductive layer is It is 18 mass parts or less with respect to 100 mass parts of acrylic resin. That is, the content of carbon black in the conductive layer is 10 parts by mass or more and 18 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer. The content of carbon black in the conductive layer is preferably 12 parts by mass or more and 18 parts by mass or less, and more preferably 14 parts by mass or more and 17 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer. preferable.

  The content of carbon black can be determined from the amount of residue obtained by thermally decomposing the conductive layer. Among the materials constituting the conductive layer according to the present invention, carbon black has the highest thermal decomposition temperature. Therefore, the conductive layer sample scraped and weighed from the electrophotographic belt was measured at a temperature not lower than the decomposition temperature of the acrylic resin and polyether ester amide and lower than the decomposition temperature of carbon black in an air atmosphere using a thermogravimetric analyzer (TGA). Proceed with thermal decomposition reaction. Thereby, content can be calculated. As specific conditions, after raising the temperature to 500 ° C. at a rate of temperature rise of 20 ° C./min, the thermal decomposition reaction other than carbon black is advanced by holding for several hours. It can be judged that the thermal decomposition reaction is completed when the weight reduction rate is 1% / hour or less. Further, the content of carbon black may be calculated from the amount of carbon black added when forming the conductive layer.

(Polyetheresteramide)
The polyether ester amide has a repeating structure of an ether group, an ester group and an amide group. Here, the absorbance of the C—O bond derived from the ether group in the infrared absorption spectrum of the polyether ester amide is A, the absorbance of the C═O bond derived from the amide group is B, and the absorbance of the C═O bond derived from the ester group. Is C. At this time, the intensity ratio [A / (A + B + C)] is 0.05 or more and 0.43 or less. The IR intensity ratio represents the proportion of ether groups in the polyether ester amide. When the numerical value is low, the proportion of ether groups is low, and when the numerical value is high, the proportion of ether groups is high. The ratio of the ether group of the polyether ester amide can be controlled by changing the number of repeating structures of the alkyl ether chain of polyalkylene glycol, which is one of the raw materials at the time of synthesis, that is, the molecular weight.

  The ether group of the polyether ester amide is a conductive unit that exhibits ionic conductivity. When the IR intensity ratio is lower than 0.05, the conductivity of the polyether ester amide itself is low, and when used in the conductive layer according to the present invention, high conductivity cannot be obtained. In addition, since the number of ether groups in one molecule affects the polarity of the molecule, when the proportion of ether groups is high, the polarity increases relatively and compatibility with polar substances such as acrylic resins increases. On the other hand, when the IR intensity ratio is higher than 0.43, the polyether ester amide is completely dissolved in the conductive layer forming paint containing the polyether ester amide. In this case, it is not possible to express higher conductivity exceeding the conductivity exhibited by the conductive layer containing carbon black as the only conductive agent, which is the effect of the present invention. Although details will be described in Examples, it is presumed that having an appropriate compatibility contributes to the effect. In this invention, it discovered that electroconductivity increased specifically by using together carbon black and polyether ester amide whose IR intensity ratio is the said range in a conductive layer. The IR intensity ratio is preferably 0.15 or more and 0.40 or less, and more preferably 0.25 or more and 0.40 or less. A method for calculating the IR intensity ratio of the polyether ester amide according to the present invention will be described later.

  The content of the polyetheresteramide in the conductive layer is preferably 3 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer. The content is more preferably 5 parts by mass or more and 20 parts by mass or less, and further preferably 5 parts by mass or more and 15 parts by mass or less. When the content is 3 parts by mass or more, sufficiently high conductivity can be obtained. Moreover, if this content is 30 mass parts or less, the fall of the mechanical characteristic of a conductive layer can fully be suppressed.

  The chemical structure of the polyetheresteramide should be identified using pyrolysis GC / MS, IR, NMR, and elemental analysis after isolating the polyetheresteramide from the conductive layer by appropriate means such as solvent extraction. Can do. The content of the polyether ester amide in the conductive layer can be determined by a quantitative ratio relationship when extracted from the conductive layer shaved from the electrophotographic belt. As a solvent used for extraction, a solvent capable of dissolving the polyether ester amide is selected. Specifically, it is preferable to use a solvent such as tetrahydrofuran (THF), ethyl acetate, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), or cyclohexanone. Further, it is preferable to use the solvent after heating it to the boiling point or lower. And the content of polyetheresteramide can be quantified by removing the solvent in the solution after extraction using a rotary evaporator, and isolating by various chromatography.

(Method for forming conductive layer)
The conductive layer can be a cured film of a coating film of a conductive layer forming paint containing a raw material monomer of an acrylic resin, a solvent that dissolves the raw material monomer, carbon black, and polyether ester amide. That is, the method for producing an electrophotographic belt according to the present invention comprises curing a coating film of a conductive layer forming paint containing a raw material monomer of an acrylic resin, a solvent for dissolving the raw material monomer, carbon black, and polyether ester amide. A step of forming a conductive layer can be included.

  For example, the raw material which comprises the said conductive layer, and a solvent are mixed, and the coating material for conductive layer formation is obtained. As the solvent, a solvent capable of dissolving the raw material monomer of the acrylic resin and the polyether ester amide is used. The term “dissolution” as used herein refers to mixing the solvent, raw material monomer, and polyether ester amide, which are raw materials other than carbon black, and stirring to homogenize, and then visually confirm the liquid after standing at room temperature for 24 hours. The solution where no sedimentation could be confirmed is defined as dissolution. At this time, if sedimentation is not confirmed, it is determined that the solution is dissolved even if the solution is slightly cloudy. Specifically, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or the like can be used as the solvent. If necessary, additives such as a polymerization initiator and a leveling agent can be added to the conductive layer forming paint. As the polymerization initiator and the leveling agent, known ones can be appropriately selected and used. The obtained conductive layer forming coating material is applied onto the endless belt-like base layer by an application means such as dip coating, spray coating, ring coating, or roll coating. Thereafter, the solvent is dried and removed, and then the coating film is cured by heat curing or an active energy irradiation device such as an ultraviolet ray or an electron beam to form a conductive layer.

[Outermost layer]
In the electrophotographic belt, an outermost layer is appropriately provided on the outer peripheral surface of the base layer or the conductive layer on the base layer for the purpose of adhesion to other contact members such as a photosensitive drum or a cleaning blade and prevention of blocking. it can. The outermost layer can include a resin. The resin is not particularly limited, but considering the thickness of the outermost layer, a resin that is soluble in a solvent and capable of forming a thin layer is preferable. As the resin, for example, a soluble polyimide curable urethane resin or acrylic resin can be used. Among these, an acrylic resin is preferable from the viewpoint of rubbing resistance and hardness. Specifically, the resin exemplified as the acrylic resin used for the conductive layer can be used as the outermost layer resin.

  In addition to the resin, filler particles and a lubricant are preferably added to the outermost layer as additives. Specific examples include the following. Alumina, titania, silica, zirconia, zinc oxide, zinc antimonate, tin oxide, ITO (tin doped indium oxide), ATO (antimony doped tin oxide), molybdenum disulfide, boron nitride, silicon nitride, layered clay mineral, silicone particles, Fluorine resin particles such as PTFE (polytetrafluoroethylene) particles, carbon black, graphite, carbon nanotubes, carbon microcoils, graphene, silicone oil, fluorine oil, perfluoropolyether. Among these, PTFE particles are preferable from the viewpoint of reducing friction. These may use 1 type and may use 2 or more types together.

  When using PTFE particles, the content of PTFE particles in the outermost layer is preferably 10 parts by mass or more and 70 parts by mass or less, and 30 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the resin in the outermost layer. It is more preferable that By setting the content of the PTFE particles within the above range, adhesion with other contact members and blocking can be prevented. In addition, a conductive agent, a curing agent, an antioxidant, an ultraviolet absorber, a pH adjuster, a crosslinking agent, a pigment, and the like can be added to the outermost layer as necessary.

  Further, the surface of the outermost layer may be provided with an uneven shape. By providing an uneven shape, in addition to the effects of the filler particles and additives such as lubricants, the contact area with other contact members is reduced, and a further reduction in frictional resistance is possible. The method for providing the uneven shape is not particularly limited. For example, the electrophotographic belt having the outermost layer supported by the core or the like is rotated in the circumferential direction while contacting the wrapping film containing abrasive grains. The method of grind | polishing the surface of an outer layer and providing uneven | corrugated shape is mentioned. Also, a method such as imprinting for contacting a mold that has been processed into a desired shape in advance can be used. The thickness of the outermost layer is preferably 0.05 μm or more and 20 μm or less, and more preferably 0.1 or more and 5 μm or less from the viewpoint of cracking and bending resistance.

<Electrophotographic device>
An electrophotographic apparatus according to an aspect of the present invention includes the electrophotographic belt according to the present invention as an intermediate transfer belt. An example of the electrophotographic apparatus will be described with reference to FIG. FIG. 3 is a schematic diagram of a full-color electrophotographic apparatus using the electrophotographic belt according to the present invention as the intermediate transfer belt 200. The intermediate transfer belt 200 is supported by three rollers including a driving roller / secondary transfer counter roller 201 and stretching rollers 202 and 203. A rubber layer having a high frictional resistance is provided on the surface of the driving roller / secondary transfer counter roller 201 to drive the intermediate transfer belt 200. The rubber layer can have conductivity with a volume resistivity of 1.0 × 10 ⁵ Ω · cm or less. The driving roller / secondary transfer counter roller 201 forms a secondary transfer roller 204 and a secondary transfer portion via the intermediate transfer belt 200. The tension roller 202 is provided with a rubber layer. The rubber layer can have conductivity with a volume resistivity of 1.0 × 10 ⁵ Ω · cm or less. Further, the tension roller 203 can be a metal roller. The secondary transfer roller 204 is pressed against the driving roller / secondary transfer counter roller 201 via the intermediate transfer belt 200. As the secondary transfer roller 204, an elastic roller having a volume resistivity of 1.0 × 10 ⁷ Ω · cm to 1.0 × 10 ⁹ Ω · cm can be used. The tension rollers 202 and 203 and the secondary transfer roller 204 rotate following the intermediate transfer belt 200.

The electrophotographic apparatus has the following configuration. A photosensitive drum that forms a toner image, an intermediate transfer belt on which the toner image is primarily transferred in contact with the photosensitive drum, a secondary transfer member that faces the intermediate transfer belt and secondary-transfers the toner image to a recording medium And a power source capable of applying a secondary transfer voltage to the secondary transfer member.
As the intermediate transfer belt, the electrophotographic belt according to the present invention is used. The power source applies a voltage to the secondary transfer member to cause a current to flow from the secondary transfer member to the photosensitive drum via the intermediate transfer belt, so that the toner is transferred from the photosensitive drum to the intermediate transfer belt. The image is primarily transferred. Thus, in the electrophotographic apparatus, the primary transfer power source and the secondary transfer power source are shared.

  An example of the electrophotographic apparatus will be specifically described with reference to FIGS. An electrophotographic apparatus shown in FIG. 3 includes an image forming unit 205a that forms a yellow image, an image forming unit 205b that forms a magenta image, an image forming unit 205c that forms a cyan image, An image forming unit 205d for forming a color image. The image forming unit 205a will be described in detail below as an example. FIG. 4 is an enlarged schematic diagram of the image forming unit 205a. The image forming unit 205a includes a photosensitive drum 206a that is an image carrier. The photosensitive drum 206a is driven to rotate at a predetermined process speed. Around the photosensitive drum 206a, a charging roller 207a as a charging member, a developing member 209a in which toner 208a is stored, and a drum cleaning member 210a are installed. Further, around the photosensitive drum 206a, an exposure member 211a is installed between the charging roller 207a and the developing member 209a. The photosensitive drum 206a is charged by a charging roller 207a and exposed by an exposure member 211a to form an electrostatic latent image (toner image). Thereafter, the electrostatic latent image is developed by the toner 208a frictionally charged in the developing member 209a, and transferred to the intermediate transfer belt 200 installed at a position facing each image forming portion by the primary transfer voltage (hereinafter, “ Referred to as “primary transfer”). Similarly, in the image forming units 205b, 205c, and 205d, primary transfer is performed in synchronization with the rotation of the intermediate transfer belt 200 to form a four-color toner composite image. At this time, it is preferable that one or more metal rollers 212 serving as a primary transfer opposing member are provided between the image forming units 205b and 205c via the intermediate transfer belt 200 at a position facing the image forming unit. By forming the primary transfer portion with the metal roller 212 that presses the intermediate transfer belt 200 against the opposing image forming portion, the primary transfer portion width (nip) can be stabilized widely.

  A recording medium 213 such as paper is supplied to a position on the intermediate transfer belt 200 that is downstream of the position of the fourth image forming unit 205d. At the same position, a secondary transfer roller 204 (secondary transfer member) is disposed. The gap formed by the intermediate transfer belt 200 and the secondary transfer roller 204 and the vicinity thereof where the toner image is transferred onto the recording medium on the intermediate transfer belt 200 is referred to as a secondary transfer portion. As shown in FIG. 3, the secondary transfer unit preferably includes a nip between the driving roller / secondary transfer counter roller 201 and the secondary transfer roller 204. When the non-image portion immediately before the toner composite image formed on the intermediate transfer belt 200 reaches the secondary transfer portion, a voltage having a polarity opposite to that of the toner is applied from the power source 214 that supplies current to the secondary transfer roller 204. The Then, when the recording medium 213 passes through the secondary transfer portion in the direction of the arrow Vf in FIG. 3, the four color toner composite images on the intermediate transfer belt 200 are collectively transferred onto the recording medium 213. . This transfer is referred to as “secondary transfer”. The recording medium 213 on which the secondary transfer has been performed is subjected to a fixing process by a fixing unit (not shown) to become a color image. On the other hand, the toner remaining on the intermediate transfer belt 200 without being subjected to the secondary transfer is scraped off by a cleaning blade 215 that comes into contact with the surface of the intermediate transfer belt 200 on which the stretching roller 202 is disposed at an arbitrary timing, so that the waste toner Collected in box 216. In this way, the surface of the intermediate transfer belt 200 returns to the initial state.

  In the electrophotographic apparatus, the transfer voltage necessary for the primary transfer is obtained from the power source 214 in addition to the transfer voltage necessary for the secondary transfer. Further, the intermediate transfer belt 200 can be connected to a constant voltage element and grounded. For example, the intermediate transfer belt 200 in the present invention has a conductive layer on the inner peripheral surface of the belt as shown in FIG. As shown in FIG. 3, the four rollers 201, 202, 203, and 212 that are in contact with the inner peripheral surface of the intermediate transfer belt 200 are connected to a Zener diode 217 that is a constant voltage element, and are grounded. Therefore, the potential of the conductive layer of the intermediate transfer belt 200 becomes constant in the circumferential direction by the voltage applied from the power source 214. As a result, the potential difference between the photosensitive drum and the intermediate transfer belt 200 in each of the image forming units 205a, 205b, 205c, and 205d is substantially equal, and the currents flowing to the photosensitive drums are also substantially equal, enabling primary transfer. Since the resistance value of the recording medium 213 itself changes due to environmental changes such as temperature and humidity during image formation, the secondary transfer voltage is preferably changed within a certain range. In the electrophotographic apparatus according to the present invention, even when the secondary transfer voltage fluctuates, for example, even when the secondary transfer voltage further increases, the Zener diode 217 is connected. Flowing. Thereby, the potential of the conductive layer can be kept constant, and the primary transferability can be stabilized. Specifically, it is preferable that the applied voltage of the power source 214 is 1000 to 3500 V and the Zener voltage is 220 to 300 V. According to the present invention, by having the transfer configuration, primary transfer and secondary transfer can be stably performed by one transfer power source.

  In addition, the electrophotographic apparatus in which the electrophotographic belt according to one embodiment of the present invention is mounted as an intermediate transfer belt can supply a sufficient transfer current to the image forming unit. Further, the electrophotographic apparatus can suppress the occurrence of cracks in the conductive layer over a long period of time.

  Hereinafter, the present invention will be described using examples and comparative examples. Prior to the examples, methods for measuring and evaluating the conductive layer of the intermediate transfer belt (hereinafter also referred to as “transfer belt”) and the materials contained in the conductive layer will be described.

<Evaluation 1. Measurement of average hardness of conductive layer>
The hardness of the conductive layer was measured using a Barcovic indenter using a microindentation hardness tester (trade name: Nanoindenter G200, manufactured by Agilent Technologies, Inc.). The measurement region was a region of 10 to 20% in the thickness direction from the outermost surface of the conductive layer, and the average hardness in this region was calculated. The results are shown in Table 1.

<Evaluation 2. Measurement of surface resistivity of conductive layer>
The surface resistivity of the conductive layer was measured using a resistivity meter (trade name: Hiresta UP MCP-HT450, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) in accordance with Japanese Industrial Standard (JIS) K6911. Under an environment of a temperature of 23 ° C. and a relative humidity of 50%, the URS probe was brought into contact with the exposed portion of the conductive layer, and the value after 10 seconds was taken as a measured value. Four points were measured in the circumferential direction of the transfer belt for each 90 ° phase, and an average value of the measured values was calculated. The results are shown in Table 1. In Table 1, “OVER” indicates that the value is equal to or greater than the upper limit of measurement, and is approximately 1.0 × 10 ¹³ Ω / □ or more.

<Evaluation 3. Infrared absorption spectrum measurement>
In order to calculate the ratio of ether groups in the polyether ester amide, the total reflection infrared absorption (ATR-IR) spectrum of the isolated polyether ester amide was measured, and the IR intensity ratio was calculated. Detailed measurement conditions and definitions of IR intensity ratio were as follows.
(Measurement condition)
Equipment Spotlight 400 Universal ATR (Perkin Elmer)
Detector MIR-TGS
Resolution 4cm ^-1
Integration times 8 times ATR crystal Diamond / ZnSe
Background Air Horizontal axis unit Wave number Vertical axis unit% A (absorbance)
Absorbance A Absorbance at the peak top in the absorption near 1100 cm ⁻¹ characteristic for the ether group (C—O stretching vibration) Absorbance B Peak top in the absorption near the 1635 cm ⁻¹ characteristic for the amide group (C═O stretching vibration) Absorbance C Absorbance C Absorbance at peak top in absorption around 1730 cm ⁻¹ characteristic of ester group (−C═O stretching vibration) IR intensity ratio = [Absorbance A / (Absorbance A + Absorbance B + Absorbance C)]
Table 2 shows the IR intensity ratios of the polyether ester amides used in the conductive layers of the transfer belts according to Examples and Comparative Examples described later based on Evaluation 3. FIG. 5 shows an example of an infrared absorption spectrum of the polyether ester amide contained in the conductive layer of the transfer belt according to this embodiment. In FIG. 5, A shows a peak in absorption (C—O stretching vibration) near 1100 cm ⁻¹ characteristic of an ether group. B shows a peak in absorption (C═O stretching vibration) near 1635 cm ⁻¹ characteristic of an amide group. C shows a peak in absorption (—C═O stretching vibration) near 1730 cm ⁻¹ characteristic of an ester group.

<Evaluation 4. Compatibility evaluation of polyetheresteramide>
When obtaining the coating material for forming the conductive layer, materials other than carbon black were mixed in advance, and the compatibility of the polyetheresteramide in the mixed solution was confirmed. The mixture was allowed to stand at room temperature for 24 hours and then visually confirmed, and the compatibility was evaluated according to the following criteria. The results are shown in Table 1.
Rank A: Slightly clouded but not settled and dissolved.
Rank B: No cloudiness or sedimentation is observed, and it completely dissolves.
Rank C: Precipitation accompanying phase separation is confirmed and does not dissolve.
Rank N: No evaluation (polyether ester amide not contained).

<Evaluation 5. Measurement of hydroxyl value>
The hydroxyl value of the acrylic resin and the raw material monomer of the acrylic resin is determined with reference to the Japanese Industrial Standard (JIS) K 0070 (acetylation method), and the hydroxyl value titration analysis by indicator titration method is performed. ) And (2). Table 1 shows the calculated hydroxyl value of the acrylic resin.
Hydroxyl value (mgKOH / g) = {(V ₁ −V ₀ ) × f ₁ × 0.5 × 56.11} / S ₁ + acid value (1)
S ₁ : Mass of collected sample (g)
V ₀ : amount of 0.5 mol / L potassium hydroxide alcohol solution required for the blank test (mL)
V ₁ : Amount of 0.5 mol / L potassium hydroxide alcohol solution required in this test (mL)
f ₁ : Factor of an alcohol solution of 0.5 mol / L potassium hydroxide (1.005)
Acid value (mgKOH / g) = {(V ₃ −V ₂ ) × f ₂ × 0.1 × 56.11} / S ₂ (2)
S ₂ : Mass of collected sample (g)
V ₂ : Amount of 0.1 mol / L potassium hydroxide alcohol solution required in the blank test (mL)
V ₃ : Amount of 0.1 mol / L potassium hydroxide alcohol solution required in this test (mL)
f ₂ : Factor (1.006) of an alcohol solution of 0.1 mol / L potassium hydroxide.
Details of the hydroxyl value titration analysis will be described below. After adding about 2 g of the sample to be measured and 5 mL of the acetylating reagent to a 200 mL Erlenmeyer flask, an air-cooled tube was attached and reacted in an oil bath at 100 ° C. for 1 hour. After allowing to cool at room temperature, 1 mL of water was added. The mixture was heated again in an oil bath at 100 ° C. for 10 minutes. After cooling, the inside of the air-cooled tube and the inner wall surface of the flask were washed away with ethanol. The solution was diluted with 30 mL of pyridine. A 1% by mass phenolphthalein solution was used as an indicator, and titration was performed with an alcohol solution of 0.5 mol / L potassium hydroxide (f = 1.005). A blank test was also performed by the same method, and the hydroxyl value was calculated from the above formula (1). As the acetylating reagent, 20 g of acetic anhydride was weighed into a flask and pyridine was added to make 100 mL.
The acid value titration analysis is described in detail below. About 2 g of a sample, 30 mL of ethanol, and 30 mL of 2-butanone were charged into a 100 mL Erlenmeyer flask and dissolved at room temperature. A 1% by mass phenolphthalein solution was used as an indicator, and titration was performed with an alcohol solution of 0.1 mol / L potassium hydroxide (f = 1.006). A blank test was also performed by the same method, and the acid value was calculated from the above formula (2).

<Evaluation 6. Image quality evaluation>
The primary transfer counter member and the like provided in the electrophotographic apparatus (trade name: LaserJet Enterprise Color M552dn, manufactured by Japan HP Co., Ltd.) were removed and changed to the apparatus configuration shown in FIG. At that time, the Zener voltage was set to 300V. Further, the transfer belt provided in the electrophotographic apparatus was removed, and a transfer belt according to each of the following examples and comparative examples was attached instead. For image evaluation, a solid image of a secondary color was output on A4 size plain paper (trade name: CS814, manufactured by Canon Inc.) using cyan and magenta developers, and the resulting solid image was output. Observation was carried out visually and with a magnifier with a magnification of 20 times. Then, the occurrence of transfer unevenness due to insufficient transfer voltage was evaluated according to the following criteria. The results are shown in Table 1.
Rank A: The transfer unevenness is not recognized in both visual observation and observation with a magnifying glass, which is very good.
Rank B: Transfer unevenness is not recognized by visual observation, which is good.
Rank C: Transfer unevenness is confirmed by visual observation.
Rank N: A uniform coating material for forming the conductive layer cannot be obtained and cannot be evaluated.

<Evaluation 7. Crack evaluation>
The evaluation of the crack of the conductive layer was performed using the same electrophotographic apparatus as in the evaluation 6. On an A4 size plain paper, 75,000 images (hereinafter referred to as “E character images”) in which the letter “E” of size 4 points was formed to have a printing density of 1% were output. For image formation, a black developer mounted on the print cartridge of the electrophotographic apparatus was used. The image was output in an environment of normal humidity and normal temperature (23 ° C., relative humidity 50%). The transfer belt after paper passing durability was removed, and the surface of the conductive layer was visually observed. And the presence or absence of the generation | occurrence | production of the crack accompanying the intensity | strength lack of a conductive layer was evaluated by the following reference | standard. The results are shown in Table 1.
Rank A: Good with no cracks observed by visual observation.
Rank C: A crack is confirmed by visual observation.
Rank N: A uniform coating material for forming the conductive layer cannot be obtained and cannot be evaluated.

  Hereinafter, specific examples and comparative examples will be described. In the following examples and comparative examples, the materials in the paint may be diluted / dispersed with a solvent, but the amount of each material used (parts by mass) is the amount related to the nonvolatile content unless otherwise specified. Means the amount of solvent (volatile matter) removed. In Table 1, the material composition of the conductive layer of the transfer belts 1 to 23 according to Examples 1 to 8 and Comparative Examples 1 to 15 and the evaluation results of the transfer belt are shown. In Table 2, the types of polyether ester amides (indicated as “PEEA (1) to (8)”) in Table 1 and the IR intensity ratio based on the evaluation 3 are shown.

[Example 1]
(Preparation of base layer)
As a base layer, a transfer belt provided in an electrophotographic apparatus (trade name: LaserJet Enterprise Color M552dn, manufactured by Japan HP Co., Ltd.) was used. The transfer belt had an endless belt shape and had a thickness of 70 μm. The volume resistivity was 2.2 × 10 ¹⁰ Ω · cm, and the surface resistivity was 1.0 × 10 ¹⁰ Ω / □.

(Formation of conductive layer)
The following materials were mixed.
・ Dipentaerythritol hexaacrylate (main component) having a hydroxyl value of 30 mgKOH / g (hereinafter referred to as “DPHA (1)”) (trade name: Aronix M-402, manufactured by Toagosei Co., Ltd.) 100 parts by mass Met Black # 273 (trade name, manufactured by Mikuni Dye Co., Ltd.) as a ketjen black (registered trademark) 15 parts by mass and a polyether ester amide having an IR intensity ratio of 0.38 (hereinafter referred to as “PEEA (1)”) (Trade name: TPAE-826, manufactured by T & K TOKA Co., Ltd.) 5 parts by mass / photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF Japan Ltd.) 5 parts by mass.
The obtained mixture was diluted with methyl ethyl ketone so that the resin solid content concentration was 10% by mass, and stirred with a stirrer to obtain a uniform coating for forming a conductive layer. This paint was uniformly applied to the inner peripheral surface of the base layer by a spray method, dried at 60 ° C. for 1 minute to remove the solvent, and then cured by irradiation with ultraviolet rays. As a result, a transfer belt 1 in which a conductive layer having a thickness of 2 μm was formed on the inner peripheral surface of the base layer was obtained. In addition, an ultraviolet irradiation device (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) was used as an ultraviolet ray source. The conductive layer was UV-cured by irradiating with ultraviolet rays until the peak illuminance at a wavelength of 365 nm was 150 mW / cm ² and the integrated light amount was 2000 mJ / cm ² . The obtained transfer belt 1 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Example 2]
A transfer belt 2 was produced in the same manner as in Example 1 except that PEEA (1) was blended in the content shown in Table 1 when the conductive layer forming coating material was prepared. The obtained transfer belt 2 was subjected to the above evaluations 1 to 7. The evaluation results are shown in Table 1.

[Example 3]
When preparing a coating for forming a conductive layer, DPHA (1) is dipentaerythritol hexaacrylate (main component) (hereinafter referred to as “DPHA (2)”) having a hydroxyl value of 52 mgKOH / g (trade name: Light Acrylate DPE- 6A, manufactured by Kyoeisha Chemical Co., Ltd.). Otherwise, the transfer belt 3 was produced in the same manner as in Example 1. The obtained transfer belt 3 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Example 4]
When preparing the coating material for forming the conductive layer, DPHA (1) is pentaerythritol tetraacrylate (main component) (hereinafter referred to as “PETA (1)”) (trade name: Aronix M-305, manufactured by Toagosei Co., Ltd.) ). Otherwise, a transfer belt 4 was produced in the same manner as in Example 1. The obtained transfer belt 4 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Examples 5 and 6]
Transfer belts 5 and 6 were produced in the same manner as in Example 2 except that carbon black was blended in the content shown in Table 1 when the conductive layer forming coating material was prepared. The obtained transfer belts 5 and 6 were subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Example 7]
(Production of polyetheresteramide)
In a flask equipped with a nitrogen inlet and a distilling tube, 100.0 g of hydrogenated polymerized fatty acid (trade name: Pripol 1009, manufactured by Croda Japan Co., Ltd.), 96.6 g of azelaic acid, and 69.9 g of hexamethylenediamine were added. Added. The temperature was raised with stirring while flowing nitrogen, and the dehydration polycondensation reaction was advanced at 250 ° C. to obtain a polyamide oligomer as a precursor of polyetheresteramide. The polyamide oligomer includes a copolymer of hexamethylene diamine to polymerized fatty acid polycondensate (N-6, 36) and hexamethylene diamine to azelaic acid polymerized fatty acid polycondensate (N-6, 9). Next, at this temperature, 39.3 g of azelaic acid and 44.6 g of triethylene glycol were added to the polyamide oligomer and mixed uniformly. Thereafter, 0.86 g of zirconium stearate was added as a catalyst, the pressure was reduced to 0.8 kPa, and the reaction was further continued for 30 minutes to obtain polyether ester amide 2 (hereinafter referred to as “PEEA (2)”). The IR intensity ratio of PEEA (2) was 0.05.

(Formation of conductive layer)
A transfer belt 7 was produced in the same manner as in Example 2 except that PEEA (1) was changed to PEEA (2) when the conductive layer-forming coating material was prepared. The obtained transfer belt 7 was subjected to Evaluations 1 to 7. The evaluation results are shown in Table 1.

[Example 8]
(Production of polyetheresteramide)
In producing the polyetheresteramide by the method described in Example 7, 89.2 g of polyethylene glycol having a number average molecular weight of 300 was used instead of triethylene glycol. Otherwise in the same manner as in Example 7, polyether ester amide 3 (hereinafter referred to as “PEEA (3)”) was obtained. The IR intensity ratio of PEEA (3) was 0.43.

(Formation of conductive layer)
A transfer belt 8 was produced in the same manner as in Example 2 except that PEEA (1) was changed to PEEA (3) when the conductive layer-forming coating material was prepared. The obtained transfer belt 8 was subjected to the above evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Examples 1-3]
Transfer belts 9 to 11 were prepared in the same manner as in Example 1 except that polyether ester amide was not added and carbon black was blended in the content shown in Table 1 when preparing the conductive layer forming coating. Produced. The obtained transfer belts 9 to 11 were subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 4]
(Production of polyetheresteramide)
In producing the polyetheresteramide by the method described in Example 7, 18.2 g of ethylene glycol was used instead of triethylene glycol. Otherwise in the same manner as in Example 7, polyether ester amide 4 (hereinafter referred to as “PEEA (4)”) was obtained. The IR intensity ratio of PEEA (4) was 0.02.

(Formation of conductive layer)
A transfer belt 12 was produced in the same manner as in Example 2 except that PEEA (1) was changed to PEEA (4) when the conductive layer-forming coating material was prepared. The obtained transfer belt 12 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 5]
(Production of polyetheresteramide)
In producing the polyether ester amide by the method described in Example 7, 118.7 g of polyethylene glycol having a number average molecular weight of 400 was used instead of triethylene glycol. Otherwise in the same manner as in Example 7, polyether ester amide 5 (hereinafter referred to as “PEEA (5)”) was obtained. The IR intensity ratio of PEEA (5) was 0.46.

(Formation of conductive layer)
A transfer belt 13 was produced in the same manner as in Example 2 except that PEEA (1) was changed to PEEA (5) when the conductive layer forming coating material was prepared. The obtained transfer belt 13 was subjected to the above evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 6]
When preparing the coating material for forming a conductive layer, PEEA (1) is an polyether ester amide having an IR intensity ratio of 0.52 (hereinafter referred to as “PEEA (6)”) (trade name: TPAE-32, T & K Corporation). To TOKA). Otherwise, the transfer belt 14 was produced in the same manner as in Example 2. The obtained transfer belt 14 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 7]
When preparing a coating material for forming a conductive layer, PEEA (1) is an polyether ester amide having an IR intensity ratio of 0.52 (hereinafter referred to as “PEEA (7)”) (trade name: Pelestat NC6321, Sanyo Chemical Industries Ltd.) Changed to company-made). Otherwise, the transfer belt 15 was produced in the same manner as in Example 2. The obtained transfer belt 15 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 8]
When preparing the coating material for forming the conductive layer, PEEA (1) is polyether ester amide having an IR intensity ratio of 0.65 (hereinafter referred to as “PEEA (8)”) (trade name: TPAE-475, T & K Co., Ltd.) To TOKA). Otherwise, the transfer belt 16 was produced in the same manner as in Example 2. The obtained transfer belt 16 was subjected to the above evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 9]
When preparing a coating for forming a conductive layer, DPHA (1) is converted to pentaerythritol tetraacrylate (hereinafter referred to as “PETA (2)”) having a hydroxyl value of 0 mg KOH / g (trade name: Light Acrylate PE-4A, Kyoeisha Chemical Co., Ltd.) (Made by Co., Ltd.) Otherwise, the transfer belt 17 was produced in the same manner as in Example 2. The obtained transfer belt 17 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 10]
When preparing the coating material for forming a conductive layer, DPHA (1) was changed to a mixture of PETA (2) and DPHA (1) (PETA (2): DPHA (1) = 2: 1 (mass ratio)). . Otherwise, the transfer belt 18 was produced in the same manner as in Example 2. The obtained transfer belt 18 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 11]
When preparing the coating material for forming a conductive layer, DPHA (1) is a mixture of DPHA (1) and 2-hydroxyethyl methacrylate (hereinafter referred to as “HEMA”) (manufactured by Tokyo Chemical Industry Co., Ltd.) (DPHA (1 ): HEMA = 2: 1 (mass ratio)). Otherwise, a transfer belt 19 was produced in the same manner as in Example 2. The obtained transfer belt 19 was subjected to Evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 12]
A transfer belt 20 was produced in the same manner as in Example 2 except that carbon black and polyether ester amide were not added when preparing the conductive layer-forming paint. The obtained transfer belt 20 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Example 13]
A transfer belt 21 was produced in the same manner as in Example 2 except that carbon black was not added when preparing the conductive layer-forming paint. The obtained transfer belt 21 was subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

[Comparative Examples 14 and 15]
Transfer belts 22 and 23 were prepared in the same manner as in Example 2 except that carbon black was not added and the polyether ester amide of the type shown in Table 1 was used when preparing the conductive layer forming coating. did. The obtained transfer belts 22 and 23 were subjected to the evaluations 1 to 7. The evaluation results are shown in Table 1.

  The evaluation results shown in Table 1 are described below. As for the surface resistivity of the conductive layer, it was found from the evaluation results of the transfer belts 1, 5 and 6 that the transfer belt according to the present invention exhibits sufficiently high conductivity even when the amount of carbon black is reduced.

  Further, regarding the transfer belt 21 containing PEEA (1) as the only conductive agent and the transfer belt 10 containing carbon black as the only conductive agent, when comparing the surface resistivity of the conductive layer, the transfer belt 21 is more conductive layer. High surface resistivity. However, the surface resistivity of the conductive layers of the transfer belts 1 and 2 using carbon black and polyether ester amide (PEEA (1)) as the conductive agent is lower than those of the transfer belts 10 and 21. That is, it was found that when the polyether ester amide according to the present invention and carbon black are used in combination as the conductive agent, the conductivity of the conductive layer is improved as compared with the case where each conductive agent is used alone.

  On the other hand, for the transfer belts 2, 7 and 8 containing the polyether ester amide having an IR intensity ratio within the range according to the present invention, and the transfer belts 12 to 16 containing the polyether ester amide outside the range, the surface resistance of the conductive layer. Contrast rates. In this case, the transfer belts 2, 7 and 8 using the polyether ester amide within this range have higher conductivity. This is considered to be related to the results of the compatibility evaluation shown in Table 1. In the compatibility evaluation of the polyether ester amide according to the present invention, precipitation was not confirmed in all Examples, but some cloudiness was confirmed. Moreover, when the cross section of the cured film of the mixed solution used for compatibility evaluation was observed with a transmission electron microscope, polyether ester amide having a diameter of about 100 nm was observed in the cured film. Furthermore, when the same observation was performed with a mixed liquid containing carbon black, it was confirmed that the polyether ester amide and carbon black were in contact. That is, when the acrylic resin according to the present invention and the polyether ester amide are combined, they exhibit appropriate compatibility and form a specific cross-sectional morphology. Thus, it is presumed that the polyether ester amide contributed to the formation of an efficient conductive path of carbon black, and the improvement in conductivity was expressed.

  In addition, regarding the surface resistivity of the conductive layer, from the evaluation results of the transfer belts 1 and 2, the conductivity is increased by increasing the amount of the polyether ester amide with respect to the acrylic resin, and the auxiliary function of forming the conductive path is Has been enhanced. However, conventionally, as described in FIG. 8 of Patent Document 1, when the amount of polyetheresteramide in the transfer belt is increased, the conductivity of the carbon black is rather inhibited and the resistivity is increased. Since the present invention shows a true reverse behavior, it is presumed that the effect of the present invention is manifested by the above-described new mechanism.

DESCRIPTION OF SYMBOLS 100 Electrophotographic belt 101 Base layer 102 Conductive layer 104 Exposed portion 200 of conductive layer Intermediate transfer belt

Claims (9)

An electrophotographic belt having at least a base layer and a conductive layer,
The conductive layer contains an acrylic resin as a binder, carbon black, and polyetheresteramide,
The hydroxyl value of the acrylic resin is 20 mgKOH / g or more and 120 mgKOH / g or less,
The carbon black content in the conductive layer is 10 parts by mass or more and 18 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer.
In the infrared absorption spectrum of the polyether ester amide, A represents the absorbance of the C—O bond derived from the ether group, B represents the absorbance of the C═O bond derived from the amide group, and C represents the absorbance of the C═O bond derived from the ester group. An electrophotographic belt, wherein the strength ratio [A / (A + B + C)] is from 0.05 to 0.43. The electrophotographic belt according to claim 1, wherein the conductive layer has a surface resistivity of 1.0 × 10 ⁷ Ω / □ or less when 10 V is applied.   3. The electron according to claim 1, wherein the conductive layer has an average hardness of 0.10 GPa or more in a region of 10 to 20% in the thickness direction from the outermost surface in a nanoindenter measurement method using a Barkovic indenter. Photo belt.   The electrophotographic belt according to claim 1, wherein all or part of the conductive layer is exposed on an outer peripheral surface or an inner peripheral surface of the electrophotographic belt.   The content of the polyether ester amide in the conductive layer is 3 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the acrylic resin in the conductive layer. The electrophotographic belt described in 1. It is a manufacturing method of the belt for electrophotography according to any one of claims 1 to 5,
The method includes the step of forming the conductive layer by curing a coating film of a conductive layer forming paint containing the acrylic resin raw material monomer, a solvent for dissolving the raw material monomer, the carbon black and the polyether ester amide. A method for producing an electrophotographic belt.   An electrophotographic apparatus comprising the electrophotographic belt according to any one of claims 1 to 5 as an intermediate transfer belt. A photosensitive drum for forming a toner image;
An intermediate transfer belt on which the toner image is primarily transferred in contact with the photosensitive drum;
A secondary transfer member facing the intermediate transfer belt and secondarily transferring the toner image to a recording medium;
A power source capable of applying a secondary transfer voltage to the secondary transfer member;
An electrophotographic apparatus comprising:
The intermediate transfer belt is an electrophotographic belt according to any one of claims 1 to 5,
The power source applies a voltage to the secondary transfer member to cause a current to flow from the secondary transfer member to the photosensitive drum via the intermediate transfer belt, so that the toner is transferred from the photosensitive drum to the intermediate transfer belt. An electrophotographic apparatus characterized by primary transfer of an image.   The electrophotographic apparatus according to claim 8, wherein the intermediate transfer belt is connected to a constant voltage element and grounded.

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