Lubricant composition, transfer apparatus, and image forming apparatus

Abstract

To provide a lubricant composition capable of ensuring supply property to an intermediate transfer belt while achieving high transferability of toner from the intermediate transfer belt to paper having irregularities.SOLUTION: A lubricant composition supplied onto an intermediate transfer belt in an intermediate transfer-type electro-photographic image forming method, comprises: solid lubricant particles which are inorganic compound particles having an average particle diameter of 120 nm or less; and a binder present on surfaces of the solid lubricant particles, in which a content of the binder is 0.01 mass% or more and 20.00 mass% or less relative to the lubricant composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a lubricant composition, a transfer device, and an image forming device. [Background technology]

[0002] In an image forming apparatus using an electrophotographic method (such as a copier, a facsimile, or a printer), a toner image formed on the surface of an image carrier is transferred to the surface of a recording medium and fixed on the recording medium to form an image. For example, an image forming apparatus using an intermediate transfer belt is used to transfer the toner image to the recording medium. From the viewpoint of improving the transferability from the intermediate transfer belt to the recording medium, the supply of a lubricant onto the intermediate transfer belt has been considered.

[0003] For example, Patent Document 1 discloses "an intermediate transfer belt for use in an electrophotographic image forming apparatus, the intermediate transfer belt having a base layer and a surface layer, the surface layer being composed of a coating layer formed of a material containing at least a binder resin and inorganic fine particles having a volume average particle diameter of 30 nm to 200 nm, the inorganic fine particles being unevenly distributed and fixed on the surface of the coating layer."

[0004] Patent Document 2 discloses "a solid lubricant to be applied to an image carrier in an electrophotographic image forming apparatus, the solid lubricant being a mixture containing a fatty acid metal salt and silicone resin particles, the number average primary particle diameter of the silicone resin particles being 10 nm or more and 250 nm or less." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-039430 A [Patent Document 2] JP 2019-120877 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a lubricant composition that provides high transferability of toner from an intermediate transfer belt to uneven paper while ensuring supplyability to an intermediate transfer belt, compared to a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter of more than 120 nm, a lubricant composition in which the binder content in the lubricant composition is less than 0.01% by mass, and a lubricant composition in which the binder content in the lubricant composition is more than 20% by mass, and to provide a transfer device and an image forming device for the lubricant composition. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> A lubricant composition to be supplied onto an intermediate transfer belt in an intermediate transfer type electrophotographic image forming method, comprising: Solid lubricant particles which are inorganic compound particles with an average particle size of 120 nm or less; a binder present on the surface of the solid lubricant particles, the binder being present in an amount of 0.01% by mass or more and 20.00% by mass or less relative to the lubricant composition; 1. A lubricant composition comprising: <2> The inorganic compound particles have an average particle size of 115 nm or less. <1> The lubricant composition according to claim 1. <3> The inorganic compound particles have an average particle size of 20 nm or more. <1> or <2> The lubricant composition according to claim 1. <4> The inorganic compound particles have an average particle size of 30 nm or more. <3> The lubricant composition according to claim 1. <5> The content of the binder in the lubricant composition is 0.10% by mass or more and 15.00% by mass or less. <1> ~ <4> The lubricant composition according to any one of claims 1 to 5. <6> The binder is a water-soluble binder. <1> ~ <5> The lubricant composition according to any one of claims 1 to 5. <7> The binder is polyvinyl alcohol. <6> The lubricant composition according to claim 1. <8> The inorganic compound particles are silica. <1> ~ <7> The lubricant composition according to any one of claims 1 to 5. <9> Martens hardness is 3N / mm 2 More than 30N / mm 2 Below is the <1> ~ <8> The lubricant composition according to any one of claims 1 to 5. <10> Martens hardness is 4N / mm 2 More than 20N / mm 2 Below is the <9> The lubricant composition according to claim 1. <11> an intermediate transfer belt onto which a toner image is transferred; a primary transfer device having a primary transfer member for primarily transferring a toner image formed on a surface of an image carrier onto a surface of the intermediate transfer belt; a secondary transfer device that is disposed in contact with a surface of the intermediate transfer belt and has a secondary transfer member that secondarily transfers the toner image transferred onto the surface of the intermediate transfer belt onto a surface of a recording medium; a cleaning device having a cleaning blade for cleaning the surface of the intermediate transfer belt; The intermediate transfer belt is provided in contact with the surface of the intermediate transfer belt. <1> ~ <10> a lubricant supplying device for supplying the lubricant composition according to any one of claims 1 to 5; A transfer device comprising: <12> a toner image forming device having an image carrier and forming a toner image on a surface of the image carrier; A transfer device that transfers the toner image formed on the surface of the image carrier to a surface of a recording medium, <11> A transfer device according to the present invention; An image forming apparatus comprising: Effect of the Invention

[0008] <1> or <6> According to the invention, there is provided a lubricant composition which ensures high transferability of toner from an intermediate transfer belt to paper having irregularities while ensuring supplyability to an intermediate transfer belt, as compared with a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter exceeding 120 nm, a lubricant composition having a binder content of less than 0.01% by mass relative to the lubricant composition, and a lubricant composition having a binder content of more than 20.00% by mass relative to the lubricant composition. <2> According to the present invention, there is provided a lubricant composition which provides high transferability of toner from an intermediate transfer belt to paper having irregularities, compared to a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter of more than 115 nm. <3> or <4> According to the present invention, there is provided a lubricant composition which provides high transferability of toner from an intermediate transfer belt to paper having irregularities, compared to a lubricant composition containing only solid lubricant particles, which are inorganic compound particles with an average particle diameter of less than 20 nm. <5> According to the invention, a lubricant composition is provided which has good supplyability when supplied to an intermediate transfer belt, compared to a lubricant composition in which the binder content in the lubricant composition is less than 0.10% by mass, and a lubricant composition is provided which has improved transferability of toner to textured paper such as embossed paper, compared to a lubricant composition in which the binder content in the lubricant composition is more than 15.00% by mass. <7> According to the present invention, there is provided a lubricant composition which is excellent in disintegration properties during mounting, compared with a lubricant composition which contains only a metal soap, typically zinc stearate, as a binder. <8> According to the present invention, there is provided a lubricant composition which provides high transferability of toner from an intermediate transfer belt to paper having irregularities, compared to a lubricant composition which contains only scaly inorganic compound particles such as boron nitride as inorganic compound particles. <9> or <10> According to the invention, the Martens hardness is 3N / mm 2 The lubricant composition has a Martens hardness of 30 N / mm or less, and the transferability of the toner to textured paper such as embossed paper is improved compared to lubricant compositions having a Martens hardness of 30 N / mm or less. 2The lubricant composition has improved supplyability to an intermediate transfer belt as compared with lubricant compositions having a viscosity of more than 1000 MPa. <11> or <12> According to the invention, a transfer device and an image forming device are provided which can obtain high transferability of toner from an intermediate transfer belt to paper having irregularities while ensuring supplyability to an intermediate transfer belt, compared to a case in which a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter of more than 120 nm, a lubricant composition in which the binder content in the lubricant composition is less than 0.01 mass %, and a lubricant composition in which the binder content in the lubricant composition is more than 20.00 mass %. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a schematic configuration diagram showing the periphery of a secondary transfer unit in another example of an image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment, which is an example of the present disclosure, will be described. These descriptions and examples are merely illustrative of the embodiment, and do not limit the scope of the embodiment.

[0011] In the numerical ranges described in the present embodiment, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in the present embodiment. In addition, in the numerical ranges described in the present embodiment, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. In this embodiment, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. When the embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this. In this embodiment, each component may contain multiple types of corresponding substances. When referring to the amount of each component in the composition in this embodiment, if multiple types of substances corresponding to each component are present in the composition, the amount refers to the total amount of the multiple types of substances present in the composition, unless otherwise specified.

[0012] [Lubricant composition] The lubricant composition according to the present embodiment is a lubricant composition that is supplied onto an intermediate transfer belt in an intermediate transfer type electrophotographic image forming method. The lubricant composition includes solid lubricant particles that are inorganic compound particles having an average particle size of 120 nm or less, and a binder that is present on the surfaces of the solid lubricant particles and has a content of 0.01% by mass or more and 20% by mass or less relative to the lubricant composition.

[0013] The lubricant composition according to the present embodiment, having the above-mentioned constitution, ensures the supplying property to the intermediate transfer belt while obtaining high transferability of the toner from the intermediate transfer belt to paper having unevenness. Although the reason for this is not clear, it is assumed as follows.

[0014] In an image forming apparatus using an intermediate transfer method in which a toner image on an image carrier is transferred to a recording medium via an intermediate transfer belt, the transferability of a toner image to a recording medium that is paper having unevenness (i.e., a recording medium having an uneven surface such as embossed paper; hereinafter, also referred to simply as "uneven paper") may decrease. This is thought to be because discharge products that are generated when forming an electrostatic latent image on the surface of the image carrier accumulate on the surface of the intermediate transfer belt as image formation is repeated, gradually increasing the adhesive force between the intermediate transfer belt and the toner. In particular, in the region at the edge of the recess in the uneven paper, the pressing force of the uneven paper against the intermediate transfer belt at the transfer position of the toner image from the intermediate transfer belt (i.e., the secondary transfer section) becomes low, and the transferability of the toner decreases.

[0015] In contrast, in this embodiment, inorganic compound particles of 120 nm or less are used as solid lubricant particles supplied onto the intermediate transfer belt. As a result, uneven shapes of 120 nm or less in height are formed on the surface of the intermediate transfer belt by the solid lubricant particles. Therefore, the contact area between the intermediate transfer belt and the toner particles transferred onto the intermediate transfer belt is reduced, and the adhesion of the toner particles to the intermediate transfer belt is reduced. As a result, the transferability of the toner to uneven paper such as embossed paper is improved.

[0016] In this embodiment, the solid lubricant particles have a binder content of 0.01% by mass or more on the surface. This causes the particles of the lubricant composition to be bound together and exist in agglomerates before being supplied to the intermediate transfer belt (for example, in a state in which the lubricant composition is contained in a supply device). The lubricant composition in agglomerates provides good supplyability when supplied to the intermediate transfer belt.

[0017] On the other hand, in this embodiment, the content of the binder in the solid lubricant particles is 20% by mass or less. As a result, the lubricant composition that exists in a bound and lumpy state before being supplied (for example, in a state housed in a supply device) is in a state in which it is easily broken down. In other words, by controlling the content of the binder in the solid lubricant particles to the above range, the particles of the lubricant composition can be loosely bound together. Therefore, the lubricant composition that was in a lump form is broken up by the impact when it is supplied to the intermediate transfer belt, and the lubricant composition exists as particles (i.e., in a non-lumpy state) on the intermediate transfer belt. Therefore, an uneven shape with a height of 120 nm or less is formed by the solid lubricant particles on the surface of the intermediate transfer belt, and the transferability of the toner to uneven paper such as embossed paper is improved.

[0018] The lubricant composition according to this embodiment will be described in detail below.

[0019] (Solid lubricant particles) The lubricant composition according to this embodiment contains solid lubricant particles, which are inorganic compound particles having an average particle size of 120 nm or less.

[0020] -Average particle size- In this embodiment, inorganic compound particles having an average particle diameter of 120 nm or less are used as the solid lubricant particles. By having an average particle diameter of 120 nm or less, the transferability of the toner to textured paper such as embossed paper is improved. The average particle diameter of the inorganic compound particles is preferably 115 nm or less, and more preferably 100 nm or less. On the other hand, the lower limit of the average particle size of the inorganic compound particles is not particularly limited, but is preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. By making the average particle size of the inorganic compound particles 20 nm or more, the uneven shape due to the solid lubricant particles is well formed on the surface of the intermediate transfer belt, the contact area between the intermediate transfer belt and the toner particles transferred onto the intermediate transfer belt is reduced, and the transferability of the toner to the uneven paper is improved.

[0021] The average particle size of the inorganic compound particles refers to the average particle size when no binder is present on the surface of the inorganic compound particles. A method for separating the binder from the surface of the inorganic compound particles will be described later. The method for measuring the average particle diameter of inorganic compound particles will be described. First, an image of inorganic compound particles without a binder on the surface is taken with a scanning electron microscope. 100 inorganic compound particles that do not overlap on the image are selected, and the area circle equivalent diameter of each particle is calculated from the projected area on the image, and the average particle diameter is calculated by calculating the arithmetic average value of the 100 particles.

[0022] -Types of inorganic compound particles- Examples of inorganic compound particles include silica particles (SiO2), titania particles (TiO2), alumina particles (Al2O3), cerium oxide particles, magnesium oxide particles, zinc oxide particles, and zirconia particles (ZrO2). Among these, silica particles are preferred as the inorganic compound particles.

[0023] By using silica particles as inorganic compound particles, when a cleaning blade is used as a member for cleaning the outer peripheral surface of the intermediate transfer belt, when silica particles are deposited at the contact portion with the cleaning blade to form a particle dam, the ability (abrasive ability) to scrape off the deposits (e.g., discharge products) can be improved, and therefore the deterioration of the transferability of the toner to the textured paper can be suppressed.

[0024] - Hydrophobization of particles - The inorganic compound particles may be subjected to a surface hydrophobic treatment. By using inorganic compound particles that have been surface-treated to be hydrophobic, the adhesive force between the toner and the inorganic compound particles is reduced, making it easier to improve the initial toner transferability and the transferability of the toner to textured paper after repeated image formation.

[0025] Examples of hydrophobic treatment agents used in surface hydrophobic treatment include known organosilicon compounds having an alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, etc.), and specific examples include silazane compounds (e.g., silane compounds such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, trimethylmethoxysilane, octyltriethoxysilane, hexamethyldisilazane, tetramethyldisilazane, etc.). One type of hydrophobic treatment agent may be used alone, or two or more types may be used in combination.

[0026] Inorganic compound particles have a surface free energy of 54 mJ / m 2 It is preferable that the surface free energy of the inorganic compound particles is within the above range. When the surface free energy of the inorganic compound particles is within the above range, the adhesion of the toner to the intermediate transfer belt is reduced, and excellent transfer retention of the toner to paper having unevenness is obtained, and particularly, excellent transfer retention of the toner to paper having unevenness is obtained in a high-speed compatible image forming apparatus. The surface free energy is adjusted by the degree of surface hydrophobic treatment of the inorganic compound particles, the selection of the hydrophobic treatment agent used, etc. The surface free energy of inorganic particles is further increased by 45 mJ / m 2 More preferably, it is 30 mJ / m or less. 2It is even more preferable that:

[0027] The surface free energy of the inorganic compound particles is measured by the following method. Based on the OWRK method, water and diiodomethane, whose surface free energies are known, are used. Water is dropped onto the surface of a powder compact of inorganic compound particles to measure the contact angle of water, and diiodomethane is dropped onto the surface of a powder compact of metal oxide to measure the contact angle of diiodomethane. The surface free energy (mJ / m 2 ) is calculated.

[0028] (Binding agent) The lubricant composition according to this embodiment contains a binder present on the surfaces of solid lubricant particles, the binder being contained in an amount of 0.01% by mass or more and 20% by mass or less relative to the lubricant composition.

[0029] -Amount of binder- The binder is 0.01% by mass or more and 20.00% by mass or less based on the total amount of the lubricant composition. When the binder content is 0.01% by mass or more based on the lubricant composition, good supply properties are obtained when the lubricant composition is supplied to the intermediate transfer belt. When the binder content is 20.00% by mass or less based on the lubricant composition, the transfer properties of the toner to textured paper such as embossed paper are improved. The lower limit of the binder content in the lubricant composition is preferably 0.10% by mass or more, and more preferably 0.50% by mass or more.The upper limit of the binder content in the lubricant composition is preferably 15.00% by mass or more, and more preferably 10.00% by mass or more.

[0030] The method for measuring the binder content will be described. First, the lubricant composition is put into a solvent (e.g., water or an organic solvent) in which the binder dissolves but the inorganic compound particles do not dissolve, and the mixture is stirred to separate the binder by dissolving it in the solvent. Then, the mass of the binder and the solid lubricant particles are measured to calculate the binder content.

[0031] -Types of binders- The binder is preferably a water-soluble binder, where water-soluble means that the amount of the binder dissolved in 100 parts by mass of water at 25° C. is 5 parts by mass or more (preferably 10 parts by mass or more).

[0032] The use of a water-soluble binder is preferable from the viewpoint of environmental load. Specifically, in the surface treatment process of the solid lubricant, the surface of the solid lubricant is treated by spraying the water-soluble binder and drying it, but this is preferable because it does not require the use of an organic solvent and has a small environmental load. Examples of the water-soluble binder include polyvinyl alcohol, silanol-modified polyvinyl alcohol, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose, starch derivatives such as oxidized starch and etherified starch, polypropylene glycol, and polyethylene glycol. Among these, polyvinyl alcohol is preferred as the binder for the purpose of reducing the intermolecular interaction with the surface-treated silica particles.

[0033] -Processing method- In the lubricant composition, a binder is present on the surfaces of solid lubricant particles. Here, a method for applying a binder to the surfaces of solid lubricant particles will be described below. First, a binder is dissolved in water to obtain an aqueous binder solution. The obtained aqueous binder solution is sprayed onto the surfaces of solid lubricant particles by spray coating, and then the water is evaporated by air drying to obtain surface-treated solid lubricant particles. Note that a known spray (sprayer) may be used for spraying, and is not particularly limited.

[0034] (Physical Properties of Lubricant Composition) The lubricant composition has a Martens hardness of 3N / mm 2 More than 30N / mm 2 It is preferable that the Martens hardness is 3N / mm 2The fact that the hardness is equal to or greater than 30 N / mm 2 means that the lubricant composition is in a state where it is easily disintegrated, that is, the particles of the lubricant composition are loosely bound together before being supplied to the intermediate transfer belt (e.g., when contained in a supply device). Therefore, the lubricant composition, which was in a lump form, is easily disintegrated by the impact when being supplied to the intermediate transfer belt, and as a result, the transferability of the toner to the textured paper is easily improved. On the other hand, when the Martens hardness is 30 N / mm 2 2 The fact that the lubricant composition is below the above range means that the particles of the lubricant composition are likely to be bonded to each other and form agglomerates. Therefore, in a state before being supplied to the intermediate transfer belt (for example, in a state in which the lubricant composition is contained in a supply device), the particles of the lubricant composition are likely to be bonded to each other and form agglomerates, and as a result, good supplyability is obtained when the lubricant composition is supplied to the intermediate transfer belt. The lower limit of the Martens hardness of the lubricant composition is 4 N / mm 2 It is preferable that the resistance is 5N / mm or more. 2 The upper limit of the Martens hardness of the lubricant composition is 20 N / mm 2 It is preferable that the resistance is less than 15N / mm 2 It is more preferable that:

[0035] The Martens hardness of a lubricant composition refers to the Martens hardness of the lubricant composition when bound into a lump. Here, a method for measuring the Martens hardness of a lubricant composition will be described. First, a method for preparing a measurement sample in the form of a lubricant composition bound together is described below. The solid lubricant particles obtained by the surface treatment method for solid lubricant particles described in the above treatment method are compressed and molded in a tablet press to prepare a measurement sample.

[0036] Next, the Martens hardness of the obtained measurement sample is measured. Martens hardness is an index showing the degree of hardness based on the load required to make a dent of a certain depth. A measurement sample is set in a dynamic ultra-microhardness tester DUH-211 (manufactured by Shimadzu Corporation) and a pyramidal diamond with 90 degrees facing each other is used to measure the load when a scratch width of 0.01 mm is generated on the measurement sample, thereby measuring the Martens hardness of the lubricant composition. The Martens hardness is measured under the following conditions: triangular thruster ridge angle: 115°, test force: 0.5 mN, load speed: 0.03 mN / sec, load holding time: 5 sec.

[0037] [Transfer device] Next, a transfer device according to an embodiment of the present disclosure will be described. The transfer device according to the present embodiment includes an intermediate transfer belt on whose surface a toner image is transferred, a primary transfer device having a primary transfer member for primarily transferring the toner image formed on the surface of an image carrier onto the surface of the intermediate transfer belt, a secondary transfer device arranged in contact with the surface of the intermediate transfer belt and having a secondary transfer member for secondarily transferring the toner image transferred onto the surface of the intermediate transfer belt onto the surface of a recording medium, a cleaning device having a cleaning blade for cleaning the surface of the intermediate transfer belt, and a lubricant supply device arranged in contact with the surface of the intermediate transfer belt and supplying a lubricant composition. The lubricant composition according to the embodiment of the present disclosure described above is used as the lubricant composition.

[0038] (Structure of intermediate transfer belt) The intermediate transfer belt has a belt body and inorganic compound particles as a solid lubricant present on the surface (that is, the outer circumferential surface) of the belt body. The belt body may be a single layer body including a resin substrate layer, or a laminate body including a resin substrate layer. Examples of the laminate including a resin substrate layer include a laminate having an elastic layer provided on the outer peripheral surface of the resin substrate layer, a laminate having a resin layer provided on the inner peripheral surface of the resin substrate layer, and a laminate having an elastic layer provided on the outer peripheral surface of the resin substrate layer and a resin layer provided on the inner peripheral surface of the resin substrate layer. The elastic layer provided on the outer peripheral surface of the resin substrate layer and the resin layer on the inner peripheral surface of the resin substrate layer are well-known layers that are used in intermediate transfer belts.

[0039] -Resin base layer- The resin substrate layer contains, for example, a resin and a conductive agent. The resin substrate layer may contain other well-known components as necessary.

[0040] ·resin Examples of the resin include polyimide resin (PI resin), polyamideimide resin (PAI resin), aromatic polyether ketone resin (e.g., aromatic polyether ether ketone resin, etc.), polyphenylene sulfide resin (PPS resin), polyetherimide resin (PEI resin), polyester resin, polyamide resin, polycarbonate resin, etc. From the viewpoints of mechanical strength and dispersibility of the conductive agent, the resin is preferably a polyimide resin (that is, a resin containing a structural unit having an imide bond), more preferably a polyimide resin or a polyamideimide resin, and most preferably a polyimide resin.

[0041] Examples of polyimide resins include imidized products of polyamic acids (precursors of polyimide resins), which are polymers of tetracarboxylic dianhydrides and diamine compounds. An example of the polyimide resin is a resin having a structural unit represented by the following general formula (I).

[0042] [ka]

[0043] In general formula (I), R 1 represents a tetravalent organic group, R 2 represents a divalent organic group. R 1Examples of the tetravalent organic group represented by the formula (1) include an aromatic group, an aliphatic group, a cyclic aliphatic group, a group in which an aromatic group and an aliphatic group are combined, and groups in which these groups are substituted. Specific examples of the tetravalent organic group include residues of tetracarboxylic dianhydrides, which will be described later. R 2 Examples of the divalent organic group represented by the formula (1) include an aromatic group, an aliphatic group, a cyclic aliphatic group, a group in which an aromatic group and an aliphatic group are combined, and groups in which these groups are substituted. Specific examples of the divalent organic group include residues of diamine compounds described below.

[0044] Specific examples of tetracarboxylic dianhydrides used as raw materials for polyimide resins include pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)sulfonic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, and ethylenetetracarboxylic dianhydride.

[0045] Specific examples of diamine compounds used as raw materials for polyimide resins include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl 4,4'-biphenyldiamine, benzidine, and 3,3'-dimethyl Benzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylpropane, 2,4-bis(β-amino tert-butyl)toluene, bis(p-β-amino-tert-butylphenyl)ether, bis(p-β-methyl-δ-aminophenyl)benzene, bis-p-(1,1-dimethyl-5-amino-pentyl)benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di(p -aminocyclohexyl)methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, Examples include 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, piperazine, H2N(CH2)3O(CH2)2O(CH2)NH2, H2N(CH2)3S(CH2)3NH2, and H2N(CH2)3N(CH3)2(CH2)3NH2.

[0046] The polyamide-imide resin includes a resin having an imide bond and an amide bond in the repeating unit. More specifically, the polyamide-imide resin may be a polymer of a trivalent carboxylic acid compound (also called tricarboxylic acid) having an acid anhydride group, and a diisocyanate compound or a diamine compound.

[0047] As the tricarboxylic acid, trimellitic anhydride and its derivatives are preferable. In addition to the tricarboxylic acid, tetracarboxylic dianhydride, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, etc. may be used in combination.

[0048] Examples of the diisocyanate compound include 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, and naphthalene-2,6-diisocyanate. The diamine compound may be a compound having a structure similar to that of the above-mentioned isocyanate, but having an amino group instead of the isocyanato group.

[0049] Here, the resin content in the resin substrate layer is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and even more preferably 75% by mass or more and 90% by mass or less, from the viewpoints of mechanical strength and volume resistivity adjustment, etc.

[0050] Conductive agent The conductive agent is a conductive material (e.g., a material with a volume resistivity of 10 7 Ω·cm or less, and so forth) or semiconductive (e.g., volume resistivity 10 7 Ω cm or more 10 13 Examples of powders include those with a surface area of ​​0.01 Ω·cm or less, and the same applies below. Specifically, the conductive agent is not particularly limited, but examples thereof include carbon black, metals (e.g., aluminum, nickel, etc.), metal oxides (e.g., yttrium oxide, tin oxide, etc.), and ion-conductive substances (e.g., potassium titanate, LiCl, etc.).

[0051] The conductive agent is selected depending on the purpose of use, but carbon black is preferred. Examples of carbon black include ketjen black, oil furnace black, channel black, acetylene black, etc. As the carbon black, surface-treated carbon black (hereinafter also referred to as "surface-treated carbon black") may be used. Surface-treated carbon black can be obtained by imparting, for example, a carboxy group, a quinone group, a lactone group, a hydroxy group, etc. to its surface. Examples of the surface treatment method include an air oxidation method in which the carbon black is reacted by contacting with air in a high-temperature atmosphere, a method in which the carbon black is reacted with nitrogen oxides or ozone at room temperature (e.g., 22°C), and a method in which the carbon black is oxidized with air in a high-temperature atmosphere and then oxidized with ozone at a low temperature.

[0052] The average particle size of carbon black is preferably from 2 to 40 nm, more preferably from 8 to 20 nm, and even more preferably from 10 to 15 nm, from the viewpoints of dispersibility, mechanical strength, volume resistivity, film-forming properties, and the like.

[0053] The average particle size of the conductive agent (particularly carbon black) is measured by the following method. First, a measurement sample having a thickness of 100 nm is taken from the resin substrate layer using a microtome, and the measurement sample is observed using a TEM (transmission electron microscope). Then, the diameter of a circle equal to the projected area of ​​each of the 50 conductive particles (i.e., the equivalent circle diameter) is taken as the particle diameter, and the average value of these is taken as the average particle diameter.

[0054] From the viewpoints of mechanical strength and volume resistivity, the content of the conductive agent is preferably 10% by mass or more and 50% by mass or less, more preferably 12% by mass or more and 40% by mass or less, and more preferably 15% by mass or more and 30% by mass or less, relative to the resin substrate layer.

[0055] -Other ingredients- Examples of other components include a filler for improving mechanical strength, an antioxidant for preventing thermal deterioration of the belt, a surfactant for improving fluidity, and a heat-resistant anti-aging agent. When other components are contained, the content of the other components is preferably more than 0% by mass and not more than 10% by mass, more preferably more than 0% by mass and not more than 5% by mass, and even more preferably more than 0% by mass and not more than 1% by mass, relative to the resin substrate layer.

[0056] -Thickness of resin substrate layer- From the viewpoint of mechanical strength, the thickness of the resin substrate layer is preferably 60 μm or more and 120 μm or less, and more preferably 80 μm or more and 120 μm or less.

[0057] The thickness of the resin substrate layer is measured as follows. That is, a cross section of the resin substrate layer in the thickness direction is observed with an optical microscope or a scanning electron microscope, the thickness of the layer to be measured is measured at 10 points, and the average value is taken as the thickness.

[0058] (Volume resistivity of intermediate transfer belt) From the viewpoint of transferability, the common logarithm of the volume resistivity of the intermediate transfer belt when a voltage of 500 V is applied for 10 seconds is preferably 9.0 (log Ω·cm) or more and 13.5 (log Ω·cm) or less, more preferably 9.5 (log Ω·cm) or more and 13.2 (log Ω·cm) or less, and particularly preferably 10.0 (log Ω·cm) or more and 12.5 (log Ω·cm) or less. The volume resistivity of the intermediate transfer belt when a voltage of 500 V is applied for 10 seconds is measured by the following method. A microcurrent meter (Advantest R8430A) is used as the resistance measuring device, and a UR probe (Mitsubishi Chemical Analytech Co., Ltd.) is used as the probe to measure the volume resistivity (log Ω cm) at 6 equally spaced points around the periphery of the intermediate transfer belt, and 3 points at the center and both ends in the width direction, for a total of 18 points, at a voltage of 500 V, application time of 10 seconds, and pressure of 1 kgf, and the average value is calculated. The measurements are also performed in an environment with a temperature of 22°C and a humidity of 55% RH.

[0059] (Surface resistivity of intermediate transfer belt) From the viewpoint of transferability to textured paper, the common logarithm of the surface resistivity when a voltage of 500 V is applied to the outer peripheral surface of the intermediate transfer belt for 10 seconds is preferably 10.0 (log Ω / suq.) or more and 15.0 (log Ω / suq.) or less, more preferably 10.5 (log Ω / suq.) or more and 14.0 (log Ω / suq.) or less, and particularly preferably 11.0 (log Ω / suq.) or more and 13.5 (log Ω / suq.) or less. The unit of surface resistivity, logΩ / suq., is a logarithmic value of the resistance per unit area, and is also expressed as log(Ω / suq.), logΩ / suquare, logΩ / □, etc. The surface resistivity when a voltage of 500 V is applied to the outer peripheral surface of the intermediate transfer belt for 10 seconds is measured by the following method. A microammeter (R8430A manufactured by Advantest) is used as the resistance measuring device, and a UR probe (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) is used as the probe to measure the surface resistivity (logΩ / suq.) of the outer peripheral surface of the endless belt at 6 equally spaced points in the circumferential direction of the outer peripheral surface of the intermediate transfer belt, and 3 points in the center and both ends in the width direction, for a total of 18 points, at a voltage of 500V, an application time of 10 seconds, and a pressure of 1kgf, and the average value is calculated. The measurements are also performed in an environment with a temperature of 22°C and a humidity of 55%RH.

[0060] <Method of manufacturing intermediate transfer belt> The method for producing the intermediate transfer belt according to the present embodiment includes, for example, a step of preparing a belt body, and a step of applying inorganic compound particles as a solid lubricant to the outer peripheral surface of the belt body.

[0061] In the step of preparing the belt body, the belt body is obtained by utilizing a known method for manufacturing an intermediate transfer belt.

[0062] The step of applying inorganic compound particles may be, for example, the following modes (1), (2) and (3), with mode (1) being preferred. (1) A mode in which a supplying member is brought into contact with a molded product of inorganic compound particles to scrape off the inorganic compound particles, and the scraped off inorganic compound particles are supplied to the surface of the belt body. (2) A molded product of inorganic compound particles is pressed directly against the intermediate transfer belt (i.e., the belt body) and abraded to supply inorganic compound particles to the surface of the belt body. (3) A mode in which an appropriate amount of powdered inorganic compound particles is placed on a supply member such as a roll, and is supplied from the supply member to the surface of the belt body.

[0063] [Transfer device] -First embodiment- The transfer device according to the first embodiment includes an intermediate transfer belt on the surface (i.e., the outer peripheral surface) of which a toner image is transferred, a primary transfer device having a primary transfer member which primarily transfers the toner image formed on the surface of an image carrier onto the surface of the intermediate transfer belt, a secondary transfer device which is arranged in contact with the surface of the intermediate transfer belt and has a secondary transfer member which secondarily transfers the toner image transferred onto the surface of the intermediate transfer belt onto the surface of a recording medium, and a cleaning device having a cleaning blade which cleans the surface of the intermediate transfer belt.The intermediate transfer belt according to the above embodiment is applied as the intermediate transfer belt.

[0064] The transfer device according to the first embodiment has the above-described configuration, and is therefore excellent in terms of transfer retention of toner onto paper having irregularities.

[0065] In the primary transfer device, a primary transfer member is disposed opposite to an image carrier with an intermediate transfer belt interposed therebetween. In the primary transfer device, a voltage of a polarity opposite to the charge polarity of the toner is applied to the intermediate transfer belt by the primary transfer member, whereby the toner image is primarily transferred onto the surface of the intermediate transfer belt.

[0066] In the secondary transfer device, the secondary transfer member is disposed on the toner image carrying side of the intermediate transfer belt. The secondary transfer device includes, for example, a backing member disposed on the opposite side of the intermediate transfer belt from the toner image carrying side together with the secondary transfer member. In the secondary transfer device, the intermediate transfer belt and the recording medium are sandwiched between the secondary transfer member and the backing member to form a transfer electric field, whereby the toner image on the intermediate transfer belt is secondarily transferred to the recording medium. The secondary transfer member may be a secondary transfer roll or a secondary transfer belt. The backing member may be, for example, a backing roll.

[0067] In the cleaning device, the cleaning blade is disposed on the toner image bearing side of the intermediate transfer belt. The cleaning device includes, for example, a cleaning blade and a backing member disposed on the opposite side of the intermediate transfer belt from the toner image bearing side. In the cleaning device, for example, the intermediate transfer belt is sandwiched between the cleaning blade and the backing member, and the surface of the intermediate transfer belt is cleaned by the cleaning blade.

[0068] The transfer device according to the present embodiment may be a transfer device that transfers a toner image onto a surface of a recording medium via multiple intermediate transfer belts. That is, the transfer device may be, for example, a transfer device that performs primary transfer of a toner image from an image carrier to a first intermediate transfer belt, secondary transfer of the toner image from the first intermediate transfer belt to a second intermediate transfer belt, and then tertiary transfer of the toner image from the second intermediate transfer belt to a recording medium. A transfer device applies the intermediate transfer belt according to the present embodiment to at least one of a plurality of intermediate transfer belts.

[0069] -Second embodiment- The transfer device according to the second embodiment includes an intermediate transfer belt having a surface onto which a toner image is transferred, a primary transfer device having a primary transfer member which performs primary transfer of the toner image formed on the surface of an image carrier onto the surface of the intermediate transfer belt, a secondary transfer device arranged in contact with the surface of the intermediate transfer belt and having a secondary transfer member which performs secondary transfer of the toner image transferred onto the surface of the intermediate transfer belt onto the surface of a recording medium, a cleaning device having a cleaning blade which cleans the surface of the intermediate transfer belt, and an inorganic compound particle supplying device arranged in contact with the surface of the intermediate transfer belt and which supplies inorganic compound particles as a solid lubricant to the surface of the intermediate transfer belt.

[0070] The transfer device according to the second embodiment has the above-described configuration, and is therefore excellent in terms of transfer retention of toner onto paper having irregularities.

[0071] In the transfer device according to the second embodiment, the inorganic compound particle supplying device is provided, for example, downstream of the secondary transfer device in the rotation direction of the intermediate transfer belt and upstream of the cleaning device in the rotation direction of the intermediate transfer belt.

[0072] The inorganic compound particle supplying device may have, for example, a molded product of inorganic compound particles as a solid lubricant, and an inorganic compound particle supplying member (the above-mentioned embodiment (1)). Examples of the molded product of inorganic compound particles include inorganic compound particles solidified together with a binder resin, and molded products obtained by compression molding inorganic compound particles. The shape of the molded product may be a rod shape, a plate shape (i.e., a blade shape), etc. Examples of the inorganic compound particle supplying member include a rotating brush and a rubber roll, among which a rotating brush is preferred. The rotating brush and the rubber roll come into contact with the molded product of the inorganic compound particles while rotating, scrape off the inorganic compound particles, and supply the scraped inorganic compound particles to the surface of the intermediate transfer belt.

[0073] As another embodiment of the inorganic compound particle supplying device, for example, a molded product of inorganic compound particles is directly pressed against the intermediate transfer belt (i.e., the belt body) (the above-mentioned embodiment (2)). The molded product of inorganic compound particles pressed against the intermediate transfer belt is worn down, so that the inorganic compound particles are supplied to the surface of the belt body.

[0074] In the transfer device according to the second embodiment, the configuration other than the inorganic compound particle supply device is similar to the configuration described in the transfer device according to the first embodiment.

[0075] [Image forming equipment] The image forming apparatus according to the present embodiment includes a toner image forming device that forms a toner image on the surface of an image carrier, and a transfer device that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium. The transfer device according to the embodiment of the present disclosure is applied to the transfer device.

[0076] An example of a toner image forming device is a device that includes an image holder, a charging device that charges the surface of the image holder, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged image holder, and a developing device that develops the electrostatic latent image formed on the surface of the image holder using a developer containing toner to form a toner image.

[0077] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus equipped with a fixing means for fixing a toner image transferred onto the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of an image holder before charging after the toner image is transferred; an apparatus equipped with a discharging means for irradiating the surface of the image holder with discharging light to discharge the surface before charging after the toner image is transferred; and an apparatus equipped with an image holder heating member for increasing the temperature of the image holder and reducing the relative temperature.

[0078] The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0079] In the image forming apparatus according to the present embodiment, for example, the portion including the image carrier may be a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including a toner image forming device and a transfer device is preferably used.

[0080] Hereinafter, an example of an image forming apparatus according to the present embodiment will be described with reference to the drawings. However, the image forming apparatus according to the present embodiment is not limited to this. Note that only the main parts shown in the drawings will be described, and the description of the rest will be omitted. Here, an example of an image forming apparatus to be described with reference to the drawings is an image forming apparatus in which the transfer device according to the second embodiment is applied as a transfer device. In an image forming apparatus in which the transfer device according to the first embodiment is applied as a transfer device, the transfer device may or may not be provided with a solid lubricant supply device.

[0081] (Image forming device) FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment.

[0082] 1, the image forming apparatus 100 according to the present embodiment is, for example, an intermediate transfer type image forming apparatus generally called a tandem type, and includes a plurality of image forming units 1Y, 1M, 1C, and 1K (an example of a toner image forming apparatus) in which toner images of each color component are formed by an electrophotographic method, a primary transfer section 10 that sequentially transfers (primary transfer) the toner images of each color component formed by each image forming unit 1Y, 1M, 1C, and 1K onto an intermediate transfer belt 15, a secondary transfer section 20 that collectively transfers (secondary transfer) the superimposed toner images transferred onto the intermediate transfer belt 15 onto a recording medium, paper K, and a fixing device 60 that fixes the secondary transferred image onto the paper K. The image forming apparatus 100 also has a control section 40 that controls the operation of each device (each section).

[0083] Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photoconductor 11 (an example of an image carrier) that rotates in the direction of arrow A and carries a toner image formed on its surface.

[0084] Around the photoconductor 11, there is provided a charger 12 as an example of a charging means for charging the photoconductor 11, and there is provided a laser exposure device 13 (the exposure beam is indicated by the symbol Bm in the figure) as an example of a latent image forming means for writing an electrostatic latent image on the photoconductor 11.

[0085] In addition, around the photoconductor 11, there is provided a developing device 14 as an example of a developing means, which contains each color component toner and makes the electrostatic latent image on the photoconductor 11 visible using the toner, and there is provided a primary transfer roll 16 which transfers each color component toner image formed on the photoconductor 11 to an intermediate transfer belt 15 at the primary transfer section 10.

[0086] Furthermore, a photoreceptor cleaner 17 that removes residual toner on the photoreceptor 11 is provided around the photoreceptor 11, and electrophotographic devices including a charger 12, a laser exposure device 13, a developer 14, a primary transfer roll 16, and the photoreceptor cleaner 17 are sequentially arranged along the rotation direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially linear fashion in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15.

[0087] The intermediate transfer belt 15 is driven (rotated) in a circular manner in the direction B shown in Fig. 1 at a speed suited to the purpose by various rolls. The various rolls include a drive roll 31 driven by a motor (not shown) excellent in constant speed performance to rotate the intermediate transfer belt 15, a support roll 32 supporting the intermediate transfer belt 15 extending in a substantially straight line along the arrangement direction of the photoconductors 11, a tensioning roll 33 that applies tension to the intermediate transfer belt 15 and functions as a correction roll to prevent the intermediate transfer belt 15 from meandering, a back roll 25 provided in the secondary transfer unit 20, and a cleaning back roll 34 provided in a cleaning unit that scrapes off residual toner on the intermediate transfer belt 15.

[0088] The primary transfer section 10 is composed of a primary transfer roll 16 arranged opposite the photoconductor 11 with the intermediate transfer belt 15 sandwiched therebetween. The primary transfer roll 16 is arranged in pressure contact with the photoconductor 11 with the intermediate transfer belt 15 sandwiched therebetween, and a voltage (primary transfer bias) of the opposite polarity to the charge polarity of the toner (negative polarity; the same applies below) is applied to the primary transfer roll 16. As a result, the toner images on the photoconductors 11 are electrostatically attracted to the intermediate transfer belt 15 in sequence, and superimposed toner images are formed on the intermediate transfer belt 15.

[0089] The secondary transfer unit 20 includes a back roll 25 and a secondary transfer roll 22 that is disposed on the toner image bearing surface side of the intermediate transfer belt 15 .

[0090] The back roll 25 has a surface resistivity of 1×10 7 Ω / □ or more 1×10 10 The hardness is set to, for example, 70° (Asker C: manufactured by Kobunshi Keiki Co., Ltd., the same applies below.) The back roll 25 is disposed on the back side of the intermediate transfer belt 15 to constitute an opposing electrode of the secondary transfer roll 22, and is in contact with a metallic power supply roll 26 to which a secondary transfer bias is stably applied.

[0091] On the other hand, the secondary transfer roll 22 has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 The secondary transfer roll 22 is a cylindrical roll of Ωcm or less. The secondary transfer roll 22 is arranged in pressure contact with the back roll 25 with the intermediate transfer belt 15 sandwiched therebetween, and the secondary transfer roll 22 is further grounded to form a secondary transfer bias between the secondary transfer roll 22 and the back roll 25, and performs a second transfer of the toner image onto the paper K transported to the secondary transfer unit 20.

[0092] Further, an intermediate transfer belt cleaning member 35 is provided so as to be freely contactable and detachable on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, which removes residual toner and paper powder remaining on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. An example of the intermediate transfer belt cleaning member 35 is a cleaning roll. However, it may also be a cleaning blade. Further, downstream of the secondary transfer section 20 of the secondary transfer roll 22, a secondary transfer roll cleaning member 22A is provided to remove residual toner and paper powder on the secondary transfer roll 22 after secondary transfer and clean the surface of the secondary transfer roll 22. The secondary transfer roll cleaning member 22A is exemplified by a cleaning blade, but may also be a cleaning roll.

[0093] Further, an inorganic compound particle supplying device 70 for supplying inorganic compound particles as a solid lubricant is provided on the intermediate transfer belt 15 downstream of the secondary transfer unit 20 and upstream of the intermediate transfer belt cleaning member 35. The inorganic compound particle supplying device 70 includes an inorganic compound particle molded product 71, an inorganic compound particle supplying member 72 that scrapes off the inorganic compound particle molded product and supplies the inorganic compound particles to the surface of the intermediate transfer belt 15, and a sliding member 73 that rubs the inorganic compound particles against the surface of the intermediate transfer belt 15 by sliding to form a coating of inorganic compound particles.

[0094] The configuration including the intermediate transfer belt 15, the primary transfer roll 16, the secondary transfer roll 22, the intermediate transfer belt cleaning member 35, and the inorganic compound particle supplying device 70 corresponds to an example of a transfer device. Here, the image forming apparatus 100 may be configured to include a secondary transfer belt (an example of a secondary transfer member) instead of the secondary transfer roll 22. Specifically, as shown in Fig. 2, the image forming apparatus 100 may include a secondary transfer device including a secondary transfer belt 23, a drive roll 23A disposed opposite to a back roll 25 with the intermediate transfer belt 15 and the secondary transfer belt 23 interposed therebetween, and an idler roll 23B that stretches the secondary transfer belt 23 together with the drive roll 23A.

[0095] Meanwhile, a reference sensor (home position sensor) 42 is disposed upstream of the yellow image forming unit 1Y, which generates a reference signal that serves as a reference for timing image formation in each of the image forming units 1Y, 1M, 1C, and 1K. An image density sensor 43 for adjusting image quality is disposed downstream of the black image forming unit 1K. This reference sensor 42 generates a reference signal by recognizing a mark provided on the back side of the intermediate transfer belt 15, and each of the image forming units 1Y, 1M, 1C, and 1K is configured to start image formation in response to an instruction from the control unit 40 based on the recognition of this reference signal.

[0096] Furthermore, in the image forming apparatus according to this embodiment, as transport means for transporting the paper K, there are provided a paper storage section 50 for storing the paper K, a paper feed roll 51 for taking out and transporting the paper K accumulated in the paper storage section 50 at a predetermined timing, a transport roll 52 for transporting the paper K fed by the paper feed roll 51, a transport guide 53 for sending the paper K transported by the transport roll 52 to the secondary transfer section 20, a transport belt 55 for transporting the paper K transported after secondary transfer by the secondary transfer roll 22 to the fixing device 60, and a fixing entrance guide 56 for guiding the paper K to the fixing device 60.

[0097] Next, a basic image forming process of the image forming apparatus according to this embodiment will be described. In the image forming apparatus of this embodiment, image data output from an image reading device (not shown) or a personal computer (PC) (not shown), etc., is subjected to image processing by an image processing device (not shown), and then image formation is performed by image forming units 1Y, 1M, 1C, and 1K.

[0098] The image processing device performs image processing on the input image data, such as shading correction, positional deviation correction, brightness / color space conversion, gamma correction, and various image editing such as frame erasure, color editing, and movement editing. The image data that has undergone image processing is converted into color material gradation data of four colors, Y, M, C, and K, and is output to the laser exposure device 13.

[0099] In the laser exposure device 13, an exposure beam Bm emitted from, for example, a semiconductor laser is irradiated onto the photoconductor 11 of each of the image forming units 1Y, 1M, 1C, and 1K in accordance with the input color material gradation data. In each of the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic latent image. The formed electrostatic latent image is developed into a toner image of each color of Y, M, C, and K by each of the image forming units 1Y, 1M, 1C, and 1K.

[0100] The toner images formed on the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer section 10 where each photoconductor 11 comes into contact with the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) of the opposite polarity to the charging polarity (negative polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner images are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform the primary transfer.

[0101] After the toner images are sequentially primarily transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves to transport the toner images to the secondary transfer unit 20. When the toner images are transported to the secondary transfer unit 20, the transport means rotates the paper feed roll 51 in accordance with the timing at which the toner images are transported to the secondary transfer unit 20, and paper K of the desired size is supplied from the paper storage unit 50. The paper K supplied by the paper feed roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport guide 53. Before reaching the secondary transfer unit 20, the paper K is temporarily stopped, and an alignment roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner images are held, thereby aligning the position of the paper K with the position of the toner image.

[0102] In the secondary transfer section 20, the secondary transfer roll 22 is pressed against the back roll 25 via the intermediate transfer belt 15. At this time, the paper K, which has been transported in time, is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) of the same polarity as the charging polarity (negative polarity) of the toner is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the back roll 25. Then, the unfixed toner images held on the intermediate transfer belt 15 are electrostatically transferred collectively onto the paper K in the secondary transfer section 20, which is pressed by the secondary transfer roll 22 and the back roll 25.

[0103] Thereafter, the paper K onto which the toner image has been electrostatically transferred is transported as it is after being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is transported to a transport belt 55 provided downstream of the secondary transfer roll 22 in the paper transport direction. The transport belt 55 transports the paper K to the fixing device 60 at an optimal transport speed for the fixing device 60. The unfixed toner image on the paper K transported to the fixing device 60 is fixed onto the paper K by being subjected to a fixing process using heat and pressure by the fixing device 60. The paper K on which the fixed image has been formed is then transported to an ejected paper storage section (not shown) provided in the ejection section of the image forming apparatus.

[0104] On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is transported to the cleaning section as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the cleaning back roll 34 and the intermediate transfer belt cleaning member 35.

[0105] Although the present embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications, changes, and improvements are possible. EXAMPLES

[0106] Hereinafter, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples. In the following description, unless otherwise specified, all "parts" and "%" are based on mass.

[0107] <Example 1> -Belt body manufacturing process- A PI precursor solution was prepared by dissolving polyamic acid, which is a polymer of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, in N-methyl-2-pyrrolidone (NMP). The PI precursor solution was a solution in which the solid content of the polyimide resin after imidization of the polyamic acid was 18 mass%. Next, carbon black (FW200: manufactured by Orion Engineered Carbon Corp., average particle size = 13 nm) was added to the PI precursor solution in an amount of 19 parts by mass per 100 parts by mass of the solid content of polyamic acid, and the mixture was mixed and stirred to prepare a carbon black-dispersed PI precursor solution. Next, while the aluminum cylinder was being rotated, the carbon black-dispersed PI precursor solution was dispensed onto the outer surface of the cylinder via a dispenser over a width of 500 mm. The cylinder was then heated and dried at 140°C for 30 minutes while kept horizontal, and then heated for 120 minutes so that the maximum temperature reached 320°C. The 80 μm-thick belt body (i.e., a single layer of polyimide resin) was cut to a width of 363 mm. Through the above steps, the intermediate transfer belt body was obtained.

[0108] -Lubricant composition- Silica particles (manufactured by CABOT, product name: TGC-110, average particle size: 115 nm) were treated using polyvinyl alcohol (PVA, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., product name: polyvinyl alcohol) as a binder in the amounts shown in Table 1 using the following method.

[0109] -Preparation of polyvinyl alcohol aqueous solution- While stirring 97 parts by mass of water, 3 parts by mass of polyvinyl alcohol (PVA, Fujifilm Wako Pure Chemical Industries, product name: polyvinyl alcohol) was gradually added. After the addition, the liquid was heated to 95°C while stirring to dissolve. After dissolution, it was cooled to room temperature (22°C) while stirring to prepare an aqueous polyvinyl alcohol solution with a solid content of 3%.

[0110] - Surface treatment - An aqueous polyvinyl alcohol solution was sprayed onto the silica particles using a sprayer so that the amount of the aqueous polyvinyl alcohol solution was the amount shown in Table 1 in terms of solid content. The particles were then air-dried at room temperature (22°C) for 24 hours to treat the surfaces of the silica particles with polyvinyl alcohol.

[0111] -Molding of lubricant composition- The surface-treated silica particles were placed in a φ13 mm die for tablet molding, and molded by applying a pressure of 30 MPa with a hydraulic pump for 1 minute. In this way, a lubricant composition in which the binder is present on the surfaces of solid lubricant particles was prepared.

[0112] <Examples 2 to 9 and Comparative Examples 1 to 5> A lubricant composition was prepared in the same manner as in Example 1, except that the type and average particle size of the inorganic compound particles and the type and amount of the binder were changed as shown in Table 1. The components shown in Table 1 are as follows. ·Inorganic compound particles Silica particles (CABOT, product name: TGC-110, average particle size: 115 nm) Silica particles (manufactured by Shin-Etsu Chemical Co., Ltd., product name: x24-9600A-80, average particle size: 80 nm) Silica particles (CABOT, product name: TG-5110, average particle size: 37 nm) Silica particles (manufactured by Shin-Etsu Chemical Co., Ltd., product name: OSG-170, average particle size: 170 nm) Silica particles (manufactured by Corefront Co., Ltd., product name: 43-17-502, average particle size: 500 nm) Boron nitride particles (MARUKA Corporation, product name: AP-100S, average particle size: 100 nm) ·Binding agent Polyvinyl alcohol (PVA, Fujifilm Wako Pure Chemical Industries, product name: polyvinyl alcohol) Carboxymethylcellulose (CMC) (Kimika Co., Ltd., product name: Kimika CMC)

[0113] -Evaluation test- The moldability of the obtained lubricant composition was evaluated. In addition, the lubricant composition was attached to a modified image forming apparatus "Versant 180 press (manufactured by Fujifilm Business Innovation Co., Ltd.)" equipped with a lubricant supplying device, and the toner adhesion and embossed paper transferability were evaluated.

[0114] (Moldability) The moldability was evaluated by the following tests. The obtained lubricant composition was allowed to drop naturally from a height of 50 mm, and the form of the lubricant composition after the drop was observed to evaluate the moldability. Evaluation criteria A (◎): The lubricant composition hardly crumbles, and there are no chips, cracks, or breaks on the surface. B (◯): The lubricant composition hardly crumbles, but chips, cracks, or breaks occur on the surface. C (△): The lubricant composition is crumbling or disintegrating. D(×): The lubricant composition cannot be molded and remains in a powder state.

[0115] (Toner Non-Electrostatic Adhesion) The toner adhesion force to the intermediate transfer belt was measured at the beginning of image formation (when 10 images were formed) and after the passage of time (when 1000 images were formed, maintenance). The toner adhesion was measured by the following method. The toner adhesion was measured by applying polyester resin particles with a volume average particle size of 4.7 μm to the outer peripheral surface of the intermediate transfer belt at a load of 46 g / cm 2After adhesion, air is blown onto the outer peripheral surface from above while increasing the blowing pressure, and the air blowing pressure (unit: MPa) is shown when all of the polyester resin particles adhered to the outer peripheral surface are separated from the outer peripheral surface.

[0116] (Embossed paper transferability) A 30% halftone blue image was printed on 1000 sheets of embossed paper (Boss Snow), and the filling of the recesses was visually confirmed initially (after 10 images were printed) and over time (after 1000 images were printed, maintenance), and the transferability was evaluated by comparing the 1st and 10th images, and the 1st and 1000th images. The evaluation criteria are as follows. A+(◎+): No white spots in the recesses, just like the first image. A(◎): No change from the first image, slight white spots can be seen in the recesses. B (○): Compared to the first sheet, the white spots in the recesses were slightly worse. C (△): Compared to the first sheet, the white spots in the recesses are significantly worse than B (○) and are unacceptable. D (×): Compared to the first sheet, the white spots in the recesses were more severe than C (△).

[0117] [Table 1]

[0118] From the above results, it can be seen that the lubricant composition of this example ensures supplyability to the intermediate transfer belt and is excellent in terms of high transferability of toner from the intermediate transfer belt to paper having unevenness, compared to the lubricant composition of the comparative example.

[0119] The present embodiment includes the following aspects. (((1))) A lubricant composition to be supplied onto an intermediate transfer belt in an intermediate transfer type electrophotographic image forming method, comprising: Solid lubricant particles which are inorganic compound particles with an average particle size of 120 nm or less; a binder present on the surface of the solid lubricant particles, the binder being present in an amount of 0.01% by mass or more and 20.00% by mass or less relative to the lubricant composition; 1. A lubricant composition comprising: (((2))) The lubricant composition according to (((1))), wherein the inorganic compound particles have an average particle size of 115 nm or less. (((3))) The lubricant composition according to (((1))) or (((2))), wherein the inorganic compound particles have an average particle size of 20 nm or more. (((4))) The lubricant composition according to (((3))), wherein the inorganic compound particles have an average particle size of 30 nm or more. (((5))) The lubricant composition according to any one of (((1))) to (((4))), wherein the content of the binder in the lubricant composition is 0.10 mass % or more and 15.00 mass % or less. (((6))) The lubricant composition according to any one of (((1))) to (((5))), wherein the binder is a water-soluble binder. (((7))) The lubricant composition according to (((6))), wherein the binder is polyvinyl alcohol. (((8))) The lubricant composition according to any one of (((1))) to (((7))), wherein the inorganic compound particles are silica. (((9))) Martens hardness is 3N / mm 2 More than 30N / mm 2 The lubricant composition according to any one of (((1))) to (((8))), which is: (((10))) Martens hardness is 4N / mm 2 More than 20N / mm 2 The lubricant composition according to (((9))), (((11))) an intermediate transfer belt onto which a toner image is transferred; a primary transfer device having a primary transfer member for primarily transferring a toner image formed on a surface of an image carrier onto a surface of the intermediate transfer belt; a secondary transfer device that is disposed in contact with a surface of the intermediate transfer belt and has a secondary transfer member that secondarily transfers the toner image transferred onto the surface of the intermediate transfer belt onto a surface of a recording medium; a cleaning device having a cleaning blade for cleaning the surface of the intermediate transfer belt; a lubricant supplying device that is provided in contact with a surface of the intermediate transfer belt and supplies the lubricant composition according to any one of (((1))) to (((10))) to the surface of the intermediate transfer belt; A transfer device comprising: (((12))) a toner image forming device having an image carrier and forming a toner image on a surface of the image carrier; A transfer device that transfers the toner image formed on the surface of the image carrier to a surface of a recording medium, the transfer device comprising: An image forming apparatus comprising:

[0120] According to the invention of (((1))) or (((6))), there is provided a lubricant composition which ensures high transferability of toner from an intermediate transfer belt to paper having irregularities while ensuring supplyability to an intermediate transfer belt, as compared with a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter exceeding 120 nm, a lubricant composition in which the binder content in the lubricant composition is less than 0.01% by mass, and a lubricant composition in which the binder content in the lubricant composition is more than 20.00% by mass. According to the invention related to (((2))), there is provided a lubricant composition which provides high transferability of a toner from an intermediate transfer belt to paper having irregularities, compared with a lubricant composition containing only solid lubricant particles, which are inorganic compound particles having an average particle diameter of more than 115 nm. According to the invention related to (((3))) or (((4))), there is provided a lubricant composition which provides high transferability of toner from an intermediate transfer belt to paper having irregularities, compared to a lubricant composition containing only solid lubricant particles, which are inorganic compound particles with an average particle diameter of less than 20 nm. According to the invention related to (((5))), there is provided a lubricant composition which exhibits good supplyability when supplied to an intermediate transfer belt, as compared with a lubricant composition in which the binder content in the lubricant composition is less than 0.10% by mass, and there is provided a lubricant composition which exhibits improved transferability of toner to textured paper such as embossed paper, as compared with a lubricant composition in which the binder content in the lubricant composition is more than 15.00% by mass. According to the invention related to (((7))), there is provided a lubricant composition which is excellent in terms of disintegration properties during mounting, compared with a lubricant composition which contains only a metal soap, typically zinc stearate, as a binder. According to the invention related to (((8))), there is provided a lubricant composition which provides high transferability of a toner from an intermediate transfer belt to paper having irregularities, compared with a lubricant composition which contains only scaly inorganic compound particles such as boron nitride as inorganic compound particles. According to the invention related to (((9))) or (((10))), the Martens hardness is 3 N / mm 2 The lubricant composition has a Martens hardness of 30 N / mm or less, and the transferability of the toner to textured paper such as embossed paper is improved compared to lubricant compositions having a Martens hardness of 30 N / mm or less. 2 The lubricant composition has improved supplyability to an intermediate transfer belt as compared with lubricant compositions having a viscosity of more than 1000 MPa. According to the invention of (((11))) or (((12))), there are provided a transfer device and an image forming device which can obtain high transferability of toner from an intermediate transfer belt to paper having irregularities while ensuring supplyability to an intermediate transfer belt, compared to a case in which a lubricant composition containing only solid lubricant particles that are inorganic compound particles having an average particle size exceeding 120 nm, a lubricant composition in which the binder content in the lubricant composition is less than 0.01% by mass, and a lubricant composition in which the binder content in the lubricant composition is more than 20.00% by mass. [Explanation of symbols]

[0121] 1Y, 1M, 1C, 1K Image forming unit 10 Primary transfer section 11 Photoreceptor 12 Charger 13 Laser exposure device 14 Developer 15 Intermediate transfer belt 16 Primary transfer roll 17 Photoconductor cleaner 20 Secondary transfer section 22 Secondary transfer roll 22A Secondary transfer roll cleaning member 25 Back roll 26 Power supply roll 31 Driving Roll 32 Support roll 33 Tensioning roll 34 Cleaning back roll 35 Intermediate transfer belt cleaning member 40 Control section 42 Reference Sensor 43 Image density sensor 50 Paper storage section 51 Paper feed roll 52 Transport roll 53 Transport guide 55 Conveyor belt 56 Fixing entrance guide 60 Fixing device 70 Inorganic compound particle supply device 71 Molded products of inorganic compound particles 72 Inorganic compound particle supply member 100 Image forming device

Claims

1. A lubricant composition to be supplied onto an intermediate transfer belt in an intermediate transfer type electrophotographic image forming method, comprising: solid lubricant particles which are inorganic compound particles with an average particle size of 120 nm or less; a binder present on the surface of the solid lubricant particles, the binder being present in an amount of 0.01% by mass or more and 20.00% by mass or less relative to the lubricant composition; 1. A lubricant composition comprising:

2. 2. The lubricant composition according to claim 1, wherein the inorganic compound particles have an average particle size of 115 nm or less.

3. 2. The lubricant composition according to claim 1, wherein the inorganic compound particles have an average particle size of 20 nm or more.

4. The lubricant composition according to claim 3, wherein the inorganic compound particles have an average particle size of 30 nm or more.

5. The lubricant composition according to claim 1, wherein the content of the binder in the lubricant composition is 0.10% by mass or more and 15.00% by mass or less.

6. The lubricant composition of claim 1 , wherein the binder is a water-soluble binder.

7. 7. The lubricant composition of claim 6, wherein the binder is polyvinyl alcohol.

8. 2. The lubricant composition of claim 1, wherein the inorganic particles are silica.

9. Martens hardness is 3N / mm ２ 30N / mm or more ２ 2. The lubricant composition of claim 1, wherein:

10. Martens hardness is 4N / mm ２ 20N / mm or more ２ 10. The lubricant composition of claim 9, wherein:

11. an intermediate transfer belt onto which a toner image is transferred; a primary transfer device having a primary transfer member for primarily transferring a toner image formed on a surface of an image carrier onto a surface of the intermediate transfer belt; a secondary transfer device that is disposed in contact with a surface of the intermediate transfer belt and has a secondary transfer member that secondarily transfers the toner image transferred onto the surface of the intermediate transfer belt onto a surface of a recording medium; a cleaning device having a cleaning blade for cleaning the surface of the intermediate transfer belt; a lubricant supplying device provided in contact with a surface of the intermediate transfer belt and supplying the lubricant composition according to any one of claims 1 to 10 to the surface of the intermediate transfer belt; A transfer device comprising:

12. a toner image forming device having an image carrier and forming a toner image on a surface of the image carrier; A transfer device that transfers the toner image formed on the surface of the image carrier to a surface of a recording medium, the transfer device comprising: the transfer device according to claim 11; An image forming apparatus comprising:

Images