Image forming device

Abstract

To provide an image forming device which, while materializing low temperature fixability, suppresses color stripes due to poor cleaning.SOLUTION: Provided is an image forming device comprising: an electrostatic charge image developer which contains a toner having toner particles, and with which a mold release agent existing in a region within 800 nm from the surface of the toner particle is 70% or more of the mold release agent for the whole of the toner particle, and the melting temperature of the mold release agent is 65°C to 80°C inclusive; a member to be cleaned; and a cleaning blade which is in contact with the outer circumference of the member to be cleaned and cleans the toner sticking to the surface of the member to be cleaned, and which contains polyurethane as a contact part coming into contact with the member to be cleaned, the contact part having a hardness of 85° to 95° inclusive, a plastic deformation work rate of 12% or less, and a surface Si amount of 15 atm% or greater.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] In an electrophotographic image forming apparatus (such as a copier, facsimile, or 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. Note that, for example, an intermediate transfer member is used to transfer the toner image to the recording medium. A cleaning blade is used to clean the image carrier, intermediate transfer member, and the like.

[0003] For example, Patent Document 1 discloses "a cleaning blade formed by cutting a plate-shaped body made of a cured product of a polyurethane resin composition, characterized in that the end surface of the cleaning blade formed by the cutting has 4 atom % or more of silicon atoms (Si) due to the adhesion of an organic siloxane and an oxygenation treatment."

[0004] Patent Document 2 describes a cleaning blade made of polyester urethane rubber for contacting a member to be cleaned to clean the surface of the member, and describes a cleaning blade made of polyester urethane rubber, in which, when an IR spectrum is measured by a μATR method on the surface of the polyester urethane rubber at the contact portion of the cleaning blade with the member to be cleaned, a CN peak (1411 cm) derived from an isocyanurate group in the polyester urethane rubber is detected. -1 ) intensity (I SI ) and the C=O peak (1726 cm ) derived from the ester group in the polyester urethane rubber. -1 ) intensity (I SE ) and the ratio (I SI / I SE) is 0.65 or more and 2.50 or less, and a siloxane compound represented by a specific structure is present on the surface of the polyester urethane rubber at the contact portion.

[0005] Patent Document 3 discloses "a cleaning blade having a rectangular elastic blade and a support member that supports the elastic blade, and which removes residue from the surface of a moving member to be cleaned by bringing the leading edge portion of the elastic blade into contact with the member, wherein at least the surface portion of the elastic blade, including the leading edge portion, is made of rubber having a hysteresis loss rate of 15% or less." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-051565 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-232312 [Patent Document 3] Japanese Patent Publication No. 2022-164315 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention addresses the problem of providing an image forming apparatus that includes: an electrostatic image developer containing a toner having toner particles, wherein the release agent present in a region within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particle, and the release agent has a melting temperature of 65°C or higher and 80°C or lower; a member to be cleaned; and a cleaning blade that comes into contact with the outer peripheral surface of the member to be cleaned and cleans the toner adhering to the surface of the member to be cleaned, wherein the cleaning blade contains polyurethane at a contact portion that comes into contact with the member to be cleaned, and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%, while realizing low-temperature fixability and suppressing color streaks due to poor cleaning, compared to an image forming apparatus that includes a cleaning blade having a contact portion that contains polyurethane at a contact portion that comes into contact with the member to be cleaned and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> an electrostatic image developer containing a toner having toner particles, wherein a release agent present in a region within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particles, and the melting temperature of the release agent is 65°C or higher and 80°C or lower; a member to be cleaned; a cleaning blade that comes into contact with the outer peripheral surface of the member to be cleaned to clean the toner adhering to the surface of the member to be cleaned, the cleaning blade having a contact portion that comes into contact with the member to be cleaned, the contact portion containing polyurethane, having a hardness of 85° or more and 95° or less, a plastic deformation power of 12% or less, and a surface Si content of 15 atm % or more; An image forming apparatus comprising: <2> The plastic deformation power is 10% or less <1> 2. The image forming apparatus according to claim 1 . <3> The amount of Si on the surface of the contact portion is 20 atm % or more <1> or <2> 2. The image forming apparatus according to claim 1 . <4> When the amount of Si on the surface of the contact portion is XA and the amount of Si at a position 50 nm deep from the surface of the contact portion is XB, XB / XA is 0.8 or more. <1> ~ <3> 10. The image forming apparatus according to claim 1, wherein <5> The XB / XA is 0.9 or more. <4> 2. The image forming apparatus according to claim 1 . <6> The contact portion contains a Si-containing compound. <1> ~ <5> 10. The image forming apparatus according to claim 1, wherein <7> the cleaning blade is in contact with the member to be cleaned with a pressing pressure of 1.5 gf / mm or more and 4.5 gf / mm or less; <1> ~ <6> 10. The image forming apparatus according to claim 1, wherein [Effects of the Invention]

[0009] <1> , or <6> According to the invention, an image forming apparatus is provided which includes an electrostatic image developer containing a toner having toner particles, wherein the release agent present in an area within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particle, and the melting temperature of the release agent is 65°C or more and 80°C or less, a member to be cleaned, and a cleaning blade which comes into contact with the outer surface of the member to be cleaned and cleans the toner adhering to the surface of the member to be cleaned, and in which the cleaning blade contains polyurethane at the contact portion that comes into contact with the member to be cleaned, and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%, thereby realizing low-temperature fixability and suppressing color streaks due to poor cleaning, compared to an image forming apparatus which has a contact portion that contains polyurethane at the contact portion that comes into contact with the member to be cleaned and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%. <2> According to the invention, an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by poor cleaning, compared to when the plastic deformation power exceeds 10%. <3> According to the invention, an image forming apparatus is provided which achieves low-temperature fixability and suppresses color streaks caused by poor cleaning, compared to when the Si content on the surface of the contact portion is less than 20 atm %. <4> According to the invention, an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by insufficient cleaning, compared to when XB / XA is less than 0.8. <5> According to the invention, an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by insufficient cleaning, compared to when XB / XA is less than 0.9.

[0010] <7> According to the invention, an image forming apparatus is provided which achieves low-temperature fixing performance while suppressing color streaks caused by poor cleaning, compared to when the cleaning blade is in contact with the member to be cleaned at a pressing pressure of less than 1.5 gf / mm. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 10 is a schematic diagram illustrating the amount of penetration d of the cleaning blade into the member to be cleaned. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present embodiment, which is an example of the present disclosure, will be described below. These descriptions and examples are intended to exemplify the embodiment, and are not intended to limit the scope of the embodiment.

[0013] In the numerical ranges described in this embodiment in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this embodiment, the upper or lower limit value of the numerical range may be replaced with the 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 present 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 sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these. 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.

[0014] [Image forming device] The image forming apparatus according to this embodiment includes: an electrostatic image developer containing a toner; a member to be cleaned; a cleaning blade that comes into contact with the outer peripheral surface of the member to be cleaned to remove the toner adhering to the surface of the member to be cleaned; Equipped with.

[0015] The toner has toner particles, and the toner particles have a release agent present in a region within 800 nm from the surface of the toner particle, which accounts for 70% or more of the release agent in the entire toner particle, and the melting temperature of the release agent is 65°C or higher and 80°C or lower. The cleaning blade has a contact portion (hereinafter referred to as the blade contact portion) that contains polyurethane, has a hardness of 85° to 95°, a plastic deformation power of 12% or less, and a surface Si content of 15 atm% or more. A cleaning blade with these characteristics is also referred to as a "specific cleaning blade."

[0016] The image forming apparatus according to this embodiment, with the above-described configuration, achieves low-temperature fixability while suppressing color streaks caused by poor cleaning. The reason for this is presumed to be as follows.

[0017] Toner particles in which the release agent present in the region within 800 nm from the surface of the toner particle accounts for 70% or more of the release agent in the entire toner particle and the melting temperature of the release agent is 65°C or higher and 80°C or lower are toner particles in which a low-melting-point release agent is disposed in the surface layer (hereinafter also referred to as "low-temperature fixing toner particles"). A toner having low-temperature fixing toner particles (hereinafter also referred to as "low-temperature fixing toner") has excellent low-temperature fixing properties.

[0018] However, low-temperature fixing toner has a tendency to have reduced heat resistance, and the surface of the low-temperature fixing toner particles is softened, which makes it easy for external additives to be embedded in them. In particular, when low-density images are repeatedly printed in a high-temperature, high-humidity environment, a large mechanical load is applied to the low-temperature fixing toner in the developing device, which makes it easy for external additives to be embedded in the low-temperature fixing toner particles. This reduces the amount of external additives that are liberated from the toner particles at the blade contact area, increasing the coefficient of friction between the cleaning blade and the member to be cleaned. When the coefficient of friction at the blade contact point increases, the behavior of the tip of the cleaning blade becomes unstable, causing poor cleaning and toner to slip through, resulting in color streaks due to poor cleaning.

[0019] Conventionally, efforts have been made to stabilize the behavior of the blade tip by reducing the coefficient of friction between the cleaning member and the cleaning blade and by increasing the hardness of the cleaning blade. However, increasing the hardness of the cleaning blade tends to increase hysteresis loss, and when the contact area of ​​the blade is locally pulled in, it cannot return to its original state, which can result in toner slipping through.

[0020] Therefore, in the image forming apparatus according to this embodiment, the amount of Si on the surface of the cleaning blade at the blade contact portion is set to 15 atm % or more, thereby realizing a low friction coefficient due to Si. Furthermore, by increasing the hardness at the blade contact area by setting the angle between 85° and 95°, and by setting the plastic deformation power to 12% or less to reduce hysteresis loss, the behavior of the tip of the cleaning blade is stabilized even if the coefficient of friction at the blade contact area increases. As a result, even when a low-temperature fixing toner is used, color streaks due to poor cleaning are suppressed.

[0021] From the above, it is presumed that the image forming apparatus according to this embodiment achieves low-temperature fixability while suppressing color streaks caused by poor cleaning.

[0022] The image forming apparatus according to this embodiment will be described in detail below.

[0023] Specifically, the image forming apparatus according to this embodiment includes, for example, an image forming apparatus including an image carrier, a charging device that charges the surface of the image carrier, an electrostatic image forming device that forms an electrostatic image on the surface of the charged image carrier, a developing device that contains an electrostatic image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer, a transfer device that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, a fixing device that fixes the toner image transferred to the surface of the recording medium, and a cleaning device that has a cleaning blade that comes into contact with the outer peripheral surface of the image carrier and cleans the toner adhering to the surface of the image carrier. An electrostatic image developer containing the above-mentioned low-temperature fixing toner is used as the electrostatic image developer, an image carrier is used as the member to be cleaned, and the above-mentioned specific cleaning blade is used as the cleaning blade.

[0024] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; an intermediate transfer type apparatus that primarily transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer medium, and then secondarily transfers the toner image transferred to the surface of the intermediate transfer medium to the surface of a recording medium; an apparatus equipped with a cleaning device that cleans the surface of the image carrier after the toner image is transferred but before it is charged; or an apparatus equipped with a static elimination device that irradiates the surface of the image carrier with static elimination light to eliminate static electricity after the toner image is transferred but before it is charged. In the case of an intermediate transfer type device, the transfer device is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer device that performs primary transfer of the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer device that performs secondary transfer of the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium. In the case of an intermediate transfer type device, at least one of an image carrier and an intermediate transfer member is used as the member to be cleaned.

[0025] In the image forming apparatus according to this embodiment, for example, the member to be cleaned, the developing device, and the cleaning device may be in a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. That is, the image forming apparatus according to this embodiment may be an apparatus that includes a member to be cleaned, a developing device, and a cleaning device, and that includes a process cartridge that is detachably attached to the image forming apparatus.

[0026] (cleaning target material) The member to be cleaned is, for example, either an image carrier or an intermediate transfer member. The member to be cleaned may be a well-known member, such as a paper transport belt or a secondary transfer belt, from which toner adhering to the surface is cleaned by a cleaning blade.

[0027] -Image holder- The image carrier may have, for example, a conductive substrate, an undercoat layer formed on the conductive substrate, and a photosensitive layer formed on the undercoat layer. The photosensitive layer may have a two-layer structure consisting of a charge generating layer and a charge transport layer. The photosensitive layer may be an organic photosensitive layer or an inorganic photosensitive layer. The image carrier may have a configuration in which a protective layer is provided on the photosensitive layer.

[0028] -Intermediate transfer body- The intermediate transfer member may be, for example, an intermediate transfer belt, or an intermediate transfer roll.

[0029] The intermediate transfer belt may be, for example, a single layer of a polyimide resin layer or a laminate having a polyimide resin layer as the outermost layer. The outer peripheral surface of the intermediate transfer belt is preferably made of a polyimide resin layer.

[0030] When the intermediate transfer belt is constructed of a laminate having a polyimide-based resin layer as the outermost layer, an intermediate transfer belt is used in which the polyimide-based resin layer is provided on a resin substrate layer. Note that an intermediate layer (e.g., an elastic layer) may be provided between the substrate layer and the polyimide-based resin layer. The resin substrate layer and the intermediate layer (elastic layer, etc.) may be well-known layers that are used in intermediate transfer belts.

[0031] The polyimide-based resin layer contains, for example, a polyimide-based resin and conductive carbon particles. The polyimide-based resin layer preferably contains a release agent. The polyimide-based resin layer may contain other well-known components as needed.

[0032] Here, the polyimide-based resin layer is a layer that contains polyimide-based resin in the largest amount by mass among the resin layer constituent components.

[0033] The polyimide resin means a resin containing a structural unit having an imide bond. Examples of polyimide resins include polyimide resins, polyamideimide resins, and polyetherimide resins. Among these, from the viewpoint of cleaning maintenance, polyimide resins and polyamideimide resins are preferred as polyimide-based resins, and polyimide resins are more preferred.

[0034] An example of the conductive carbon particles is carbon black. Examples of carbon black include ketjen black, oil furnace black, channel black, acetylene black, etc. Surface-treated carbon black (hereinafter also referred to as "surface-treated carbon black") may also be used as the carbon black. Surface-treated carbon black can be obtained by adding, for example, a carboxy group, a quinone group, a lactone group, a hydroxy group, etc. to its surface. Examples of surface treatment methods include an air oxidation method in which the carbon black is reacted 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.

[0035] (cleaning blade) The cleaning blade has a blade contact portion that includes polyurethane. The cleaning blade may have, for example, a single layer structure, a two layer structure, a three or more layer structure, or other structure. An example of a cleaning blade having a single layer structure is a cleaning blade whose entire structure, including the contact portion that comes into contact with the member to be cleaned, is made of a single material (that is, a cleaning blade made of a contact member). An example of a two-layer cleaning blade is a cleaning blade provided with a first layer made of a contact member including a contact portion that comes into contact with the member to be cleaned, and a second layer serving as a back surface layer formed on the back side of the first layer and made of a material different from that of the contact member. An example of a cleaning blade having three or more layers is a cleaning blade having another layer between the first and second layers of the two-layer cleaning blade. The cleaning blade is used while being supported on, for example, a rigid plate-like support material.

[0036] -hardness- The hardness of the blade contact portion is 85° or more and 95° or less, and preferably 88° or more and 93° or less. If the hardness of the blade contact area is less than 85°, the blade will curl up, causing toner to slip through, resulting in color streaks, and also reducing wear resistance. If the hardness of the blade contact portion exceeds 95°, the tip of the blade contact portion will not be able to follow the cleaning member well, resulting in poor cleaning performance and the occurrence of color streaks.

[0037] The hardness of the blade contact portion was measured as follows. Hardness is measured in accordance with the hardness testing method specified in JIS K6253 (1997) using a Type A durometer specified in JIS K7215 (1986). Specifically, a Type A durometer (manufactured by Kobunshi Keisokuki) specified in JIS K7215 (1986) is used, and the indenter is pressed against the contact point and the maximum value on the pointer is read within one second. This measurement is then repeated five times, and the JIS-A hardness of the contact point is calculated from the average value.

[0038] -Plastic deformation power- The plastic deformation power of the blade contact portion is 12% or less, and preferably 10% or less. If the plastic deformation power of the blade contact area exceeds 12%, when the blade contact area is locally pulled in, it cannot return to its original state, causing toner to slip through, resulting in color streaks. The lower limit of the plastic deformation power of the blade contact portion is, for example, 5% or more from the viewpoint of suppressing blade squeal.

[0039] The method for measuring the plastic deformation power of the blade contact portion is as follows. Using a nanoindenter (Fisher Instruments, PICODENTOR HM500), the elastic deformation power was measured by nanoindentation with a test load of 0.5 mN and indenter types: a 115° triangular pyramidal indenter and a Berkovich-type diamond indenter. The plastic deformation power was calculated using the formula: plastic deformation power ~ 100% - elastic deformation power.

[0040] -Si content- The Si content on the surface of the blade contact portion is 15 atm % or more, preferably 18 atm % or more, and more preferably 20 atm % or more. If the Si content on the surface of the blade contact portion is less than 15 atm %, the coefficient of friction between the blade contact portion and the member to be cleaned increases, causing the blade to curl up and allowing toner to slip through, resulting in color streaks. The upper limit of the amount of Si on the surface of the blade contact portion is, for example, 25 atm % or less from the viewpoint of suppressing color streaks.

[0041] When the amount of Si on the surface of the blade contact portion is XA and the amount of Si at a position 50 nm deep from the surface of the blade contact portion is XB, XB / XA is preferably 0.8 or more, more preferably 0.85 or more, and even more preferably 0.9 or more. If XB / XA is less than 0.8, the low friction coefficient at the contact portion of the blade is maintained even with wear, and the occurrence of color streaks is easily suppressed. In particular, the maintenance of suppression of color streaks is improved. The upper limit of XB / XA is, for example, 0.95 or less from the viewpoint of blade chipping.

[0042] The method for measuring the amount of Si on the surface of the blade contact portion is as follows. A sample is taken from the blade contact area, and the surface of the sample is analyzed by X-ray Photoelectron Spectroscopy (XPS) under the following conditions. The amount of Si (atm%) relative to the total amount (atm%) of the elements is calculated from the peak intensities of N, C, O, F, and Si. XPS equipment: ULVAC-PHI, VersaProbe II Etching gun: Argon gun Acceleration voltage: 5kV Emission current: 20mA Sputtering area: 2mm x 2mm Sputtering rate: 3nm / min (SiO2 equivalent)

[0043] The method for measuring the amount of Si at a depth of 50 nm from the surface of the blade contact portion is as follows. A sample was taken from the blade contact area and etched by sputtering to a depth of 50 nm from the surface. The etched surface was then analyzed by X-ray photoelectron spectroscopy (XPS) under the above conditions, and the amount of Si (atm%) relative to the total amount (atm%) of the elements was determined from the peak intensities of N, C, O, F, and Si.

[0044] -Configuration of blade contact area- The blade contact portion comprises polyurethane. The hardness and plastic deformation power of the blade contact portion can be adjusted to fall within the above ranges by adjusting the ratio of hard segments to soft segments in the polyurethane and the amount of Si-containing compound blended with respect to the polyurethane. In order to set the amount of Si on the surface of the blade contact portion and XB / XA within the above ranges, the blade contact portion preferably contains a Si-containing compound.

[0045] Polyurethane The polyurethane is a polyurethane obtained by polymerizing at least a polyol component and a polyisocyanate component. If necessary, the polyurethane may be a polyurethane obtained by polymerizing a resin having a functional group capable of reacting with an isocyanate group of the polyisocyanate in addition to the polyol component.

[0046] The polyurethane preferably has a hard segment and a soft segment. The terms "hard segment" and "soft segment" refer to segments in which the former is made of a material that is relatively harder than the material that constitutes the latter, and the latter is made of a material that is relatively softer than the material that constitutes the former. Examples of materials constituting the hard segments (hard segment materials) include low-molecular-weight polyol components among polyol components, resins having functional groups capable of reacting with the isocyanate groups of polyisocyanates, etc. On the other hand, examples of materials constituting the soft segments (soft segment materials) include high-molecular-weight polyol components among polyol components.

[0047] Here, the average particle size of the hard segment aggregates is preferably 1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. By setting the average particle size of the hard segment aggregates to 1 μm or more, the friction resistance on the surface of the contacting member is likely to be reduced, which stabilizes blade behavior and makes it easier to suppress localized wear. On the other hand, by setting the average particle size of the hard segment aggregates to 10 μm or less, the occurrence of chipping is easily suppressed.

[0048] The average particle size of the hard segment aggregates is measured as follows: Using a polarizing microscope (Olympus BX51-P), images are taken at a magnification of ×20, and the images are binarized by image processing. The particle diameters (circle-equivalent diameters) of the aggregates are measured at five points per cleaning blade (the particle diameters of five aggregates per point are measured) for 20 cleaning blades, and the average particle diameter is calculated from a total of 500 particles. The images were binarized using the image processing software OLYMPUS Stream essentials (Olympus Corporation), and the hue / saturation / brightness thresholds were adjusted so that the crystalline portion and hard segment aggregates were black and the amorphous portion (corresponding to the soft segment) was white.

[0049] Polyol component The polyol component includes a high molecular weight polyol and a low molecular weight polyol.

[0050] The polymer polyol component is a polyol having a number average molecular weight of 500 or more (preferably 500 or more and 5000 or less). Examples of the polymer polyol component include well-known polyols such as polyester polyols obtained by dehydration condensation of low molecular weight polyols and dibasic acids, polycarbonate polyols obtained by reaction of low molecular weight polyols with alkyl carbonates, polycaprolactone polyols, and polyether polyols. Commercially available polymer polyols include PLACCEL 205 and PLACCEL 240 manufactured by Daicel Corporation.

[0051] Here, the number average molecular weight is a value measured by gel permeation chromatography (GPC). The same applies hereinafter.

[0052] These polymer polyols may be used alone or in combination of two or more.

[0053] The polymerization ratio of the high molecular weight polyol component is preferably 30 mol % or more and 50 mol % or less, and more preferably 40 mol % or more and 50 mol % or less, based on the total polymerization components of the polyurethane.

[0054] The low molecular weight polyol component is a polyol having a molecular weight (number average molecular weight) of less than 500. Molecular polyols are materials that function as chain extenders and cross-linking agents.

[0055] Examples of low molecular weight polyol components include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol. Among these, 1,4-butanediol is preferably used as the low molecular weight polyol component.

[0056] Examples of the low molecular weight polyol component include diols (2 functional), triols (3 functional), and tetraols (4 functional), which are well known as chain extenders and crosslinking agents. These polyols may be used alone or in combination of two or more.

[0057] The polymerization ratio of the low molecular weight polyol component is preferably more than 50 mol% and 75 mol% or less, more preferably 52 mol% or more and 75 mol% or less, more preferably 55 mol% or more and 75 mol% or less, and even more preferably 55 mol% or more and 60 mol% or less, based on the total polymerization components of the polyurethane.

[0058] Polyisocyanate component Examples of the polyisocyanate component include 4,4'-diphenylmethane diisocyanate (MDI), 2,6-toluene diisocyanate (TDI), 1,6-hexane diisocyanate (HDI), 1,5-naphthalene diisocyanate (NDI), and 3,3-dimethylbiphenyl-4,4'-diisocyanate (TODI).

[0059] As the polyisocyanate component, 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), and hexamethylene diisocyanate (HDI) are more preferable.

[0060] These polyisocyanate components may be used alone or in combination of two or more.

[0061] The polymerization ratio of the polyisocyanate component is preferably 5 mol % or more and 25 mol % or less, and more preferably 10 mol % or more and 20 mol % or less, based on the total polymerization components of the polyurethane.

[0062] Resins with functional groups that can react with isocyanate groups The resin having a functional group capable of reacting with an isocyanate group (hereinafter referred to as "functional group-containing resin") is preferably a flexible resin, and from the viewpoint of flexibility, it is more preferably an aliphatic resin having a linear structure. Specific examples of functional group-containing resins include acrylic resins containing two or more hydroxyl groups, polybutadiene resins containing two or more hydroxyl groups, and epoxy resins containing two or more epoxy groups.

[0063] Commercially available acrylic resins containing two or more hydroxyl groups include, for example, Actflow (grades: UMB-2005B, UMB-2005P, UMB-2005, UME-2005, etc.) manufactured by Soken Chemical & Engineering Co., Ltd.

[0064] Commercially available polybutadiene resins containing two or more hydroxyl groups include, for example, R-45HT manufactured by Idemitsu Kosan Co., Ltd.

[0065] As epoxy resins having two or more epoxy groups, conventional general epoxy resins are It is desirable that the epoxy resin is not hard and brittle as in the case of conventional epoxy resins, but is more flexible and tough than conventional epoxy resins. As the above-mentioned epoxy resin, for example, in terms of molecular structure, it is preferable that the epoxy resin has a structure (flexible skeleton) in its main chain structure that can increase the mobility of the main chain, and examples of the flexible skeleton include an alkylene skeleton, a cycloalkane skeleton, and a polyoxyalkylene skeleton, and a polyoxyalkylene skeleton is particularly preferable. In terms of physical properties, epoxy resins with a lower viscosity relative to their molecular weight than conventional epoxy resins are preferred. Specifically, the weight-average molecular weight is preferably within the range of 900±100, and the viscosity at 25°C is preferably within the range of 15,000±5,000 mPa·s, and more preferably within the range of 15,000±3,000 mPa·s. Commercially available epoxy resins with these properties include, for example, EPICLON EXA-4850-150 manufactured by DIC.

[0066] The polymerization ratio of the functional group-containing resin is preferably set within a range that does not impair the properties of the cleaning blade.

[0067] Polyurethane manufacturing method The polyurethane can be produced by a general polyurethane production method such as a prepolymer method or a one-shot method. The prepolymer method is suitable for this embodiment because it can produce polyurethane with excellent abrasion resistance and chipping resistance, but the production method is not limited thereto. The cleaning blade is produced by forming the cleaning blade composition prepared by the above method into a sheet using, for example, centrifugal molding or extrusion molding, and then cutting the sheet.

[0068] Examples of catalysts used in the production of polyurethane include amine compounds such as tertiary amines, quaternary ammonium salts, and organometallic compounds such as organotin compounds. Examples of the tertiary amine include trialkylamines such as triethylamine, tetraalkyldiamines such as N,N,N',N'-tetramethyl-1,3-butanediamine, aminoalcohols such as dimethylethanolamine, ethoxylated amines, ethoxylated diamines, ester amines such as bis(diethylethanolamine) adipate, triethylenediamine (TEDA), cyclohexylamine derivatives such as N,N-dimethylcyclohexylamine, morpholine derivatives such as N-methylmorpholine and N-(2-hydroxypropyl)-dimethylmorpholine, and piperazine derivatives such as N,N'-diethyl-2-methylpiperazine and N,N'-bis-(2-hydroxypropyl)-2-methylpiperazine.

[0069] Examples of quaternary ammonium salts include 2-hydroxypropyltrimethylammonium octylate, 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) octylate, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) octylate, DBU-oleate, DBU-p-toluenesulfonate, DBU-formate, and 2-hydroxypropyltrimethylammonium formate.

[0070] Examples of organotin compounds include dialkyltin compounds such as dibutyltin dilaurate and dibutyltin di(2-ethylhexoate), stannous 2-ethylcaproate, and stannous oleate.

[0071] Among these catalysts, the tertiary ammonium salt triethylenediamine (TEDA) is used due to its hydrolysis resistance, while quaternary ammonium salts are preferred due to their processability. Among quaternary ammonium salts, 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) octylate, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) octylate, and DBU formate are preferred due to their high reactivity.

[0072] The content of the catalyst is preferably in the range of 0.0005% by mass to 0.03% by mass, and particularly preferably 0.001% by mass to 0.01% by mass, of the total polyurethane constituting the contact member. These may be used alone or in combination of two or more.

[0073] ·Si-containing compounds A suitable example of the Si-containing compound is silica particles. The silica particles may be particles containing silica, i.e., SiO2 as the main component, and may be crystalline or amorphous. The silica particles may be particles produced using silicon compounds such as water glass or alkoxysilane as raw materials, or may be particles obtained by pulverizing quartz.Specific examples of the silica particles include sol-gel silica particles, aqueous colloidal silica particles, alcoholic silica particles, fumed silica particles obtained by a gas phase method, and fused silica particles.

[0074] The average primary particle size of the silica particles is preferably 100 nm or more and 500 nm or less, and more preferably 200 nm or more and 350 nm or less, from the viewpoint of improving the low coefficient of friction at the blade contact portion. The average primary particle size of silica particles is measured as follows: The particle size of silica particles is the diameter of a circle having the same area as the image of a primary particle (so-called equivalent circle diameter). Silica particles are observed using a scanning electron microscope (SEM) and electron microscope images are taken. The circle-equivalent diameter of the silica particles in the obtained electron microscope image is determined by image analysis. This operation is performed on 100 silica particles. The particle diameter (50% diameter, D50v) that is the cumulative 50% from the smallest diameter side in the number-based distribution of primary particle diameters of each silica particle is then defined as the average primary particle diameter of the silica particles.

[0075] As the Si-containing compound, a silicone-based polymer may be used in addition to silica particles.

[0076] The content of the Si-containing compound is preferably 10% by mass or more and 35% by mass or less, and more preferably 15% by mass or more and 25% by mass or less, relative to the polyurethane, from the viewpoint of reducing the coefficient of friction at the blade contact portion.

[0077] -Cleaning blade pressure- The cleaning blade preferably contacts the member to be cleaned with a pressing pressure of 1.5 gf / mm to 4.5 gf / mm, more preferably 2.0 gf / mm to 3.5 gf / mm. When the pressing pressure NF is 1.5 gf / mm or more, the occurrence of color streaks due to poor cleaning is easily suppressed. When the pressing pressure NF is 4.5 gf / mm or less, the occurrence of toner filming (a phenomenon in which toner adheres to the surface of the member to be cleaned in a crushed and stretched state) on the surface of the member to be cleaned is suppressed.

[0078] Here, the pressing pressure NF of the cleaning blade is calculated by the following formula. Formula: Pressing pressure NF = k × d In the formula, k is the spring constant specific to the cleaning blade, and d is the amount of penetration of the cleaning blade into the intermediate transfer belt (see FIG. 2). The spring constant k specific to the cleaning blade is determined by applying a displacement to the cleaning blade and measuring the load with a load cell. The amount of penetration d of the cleaning blade into the intermediate transfer belt is calculated by fixing the cleaning blade to a support member and calculating the amount of displacement of the cleaning blade when the cleaning blade is brought into contact with the intermediate transfer belt. In FIG. 2, BE denotes a member to be cleaned, CB denotes a cleaning blade, and CBS denotes a support member for supporting the cleaning blade.

[0079] The depth d of the cleaning blade digging into the member to be cleaned is preferably 0 mm or more and 10 mm or less, and more preferably 0.01 mm or more and 5 mm or less.

[0080] (Electrostatic image developer) The electrostatic image developer includes a toner. The electrostatic image developer may be a one-component developer containing only toner, or may be a two-component developer containing a mixture of toner and carrier.

[0081] -toner- The toner comprises toner particles. The toner particles contain, for example, a binder resin and a release agent, and may contain other internal additives such as a colorant. The toner particles have a release agent present in a region within 800 nm from the surface of the toner particle that accounts for 70% or more of the release agent in the entire toner particle, and the melting temperature of the release agent is 65°C or higher and 80°C or lower.

[0082] --Mold release agent-- The melting temperature of the release agent is 65° C. or higher and 80° C. or lower, preferably 68° C. or higher and 77° C. or lower, and more preferably 70° C. or higher and 75° C. or lower. When the melting temperature of the release agent is 80° C. or lower, the low-temperature fixability of the image can be improved. On the other hand, when the melting temperature of the release agent is 65° C. or higher, the occurrence of toner filming on the surface of the member to be cleaned can be suppressed.

[0083] The melting temperature of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" described in the method for determining the melting temperature in JIS K-7121-1987 "Method for measuring transition temperatures of plastics."

[0084] 70% or more of the total release agent is present within 800 nm from the surface of the toner particles (hereinafter, the proportion of the release agent present within 800 nm from the surface of the toner particles is also referred to as the "surface proportion of the release agent"). The surface layer ratio of the release agent is 70% or more, preferably 75% or more, and more preferably 80% or more. The upper limit of the surface layer ratio of the release agent is preferably 100%. By making the surface layer ratio of the release agent 70% or more, the low-temperature fixability of the image can be improved.

[0085] Here, a method for measuring the surface layer proportion of the release agent will be described. The samples and images for measurement are prepared in the following manner. The toner is mixed and embedded in epoxy resin, and the epoxy resin is solidified. The resulting solidified product is cut using an ultramicrotome (Leica Ultracut UCT) to prepare a thin section sample with a thickness of 80 nm to 130 nm. An SEM image of the thin section sample is then obtained using an ultra-high resolution field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation S-4800). In the SEM image, a cross section of a toner particle whose maximum length is 85% or more of the volume average particle diameter of the toner particle is selected, and the domain of the release agent is observed. The area of ​​the release agent in the entire toner particle and the area of ​​the release agent present within 800 nm from the surface of the toner particle are determined, and the ratio of the two areas (area of ​​the release agent present within 800 nm from the surface of the toner particle / area of ​​the release agent in the entire toner particle) is calculated. This calculation is then performed for 100 toner particles, and the average value is taken as the surface layer ratio of the release agent. The reason for selecting a toner particle cross section whose maximum length is 85% or more of the volume average particle diameter of the toner particle is that a cross section of less than 85% of the volume average particle diameter is expected to be a cross section of the end of a toner particle, and the cross section of the end of a toner particle does not well reflect the state of the domains in the toner particle.

[0086] As a method for controlling the surface layer ratio of the release agent to 70% or more, for example, a method in which the toner particles have a core-shell structure and the release agent is used when forming the shell can be mentioned.

[0087] Examples of release agents include hydrocarbon waxes such as paraffin wax, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited to these. As the release agent, for example, a hydrocarbon wax is preferably used. The hydrocarbon wax is a wax having a hydrocarbon skeleton, and examples thereof include Fischer-Tropsch wax, polyethylene wax (wax having a polyethylene skeleton), polypropylene wax (wax having a polypropylene skeleton), paraffin wax (wax having a paraffin skeleton), and microcrystalline wax. Among these, from the viewpoint of fixability, Fischer-Tropsch wax, polyethylene wax, or polypropylene wax is preferable as the hydrocarbon wax. Furthermore, from the viewpoint of fixability, it is preferable that multiple types of hydrocarbon waxes are contained in the toner particles. The proportion of the hydrocarbon wax in the total release agent is 85% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass.

[0088] The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 20% by mass or less, even more preferably 3% by mass or more and 15% by mass or less, and still more preferably 5% by mass or more and 15% by mass or less, based on the total amount of the toner particles.

[0089] --Binder resin-- Examples of binder resins include vinyl resins, non-vinyl resins (e.g., epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, modified rosin, etc.), mixtures of vinyl resins and non-vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the coexistence of non-vinyl resins.

[0090] As the binder resin, for example, a polyester resin is preferably used, and the proportion of the polyester resin to the total binder resin is, for example, 75% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass.

[0091] Examples of polyester resins include known amorphous polyester resins. The polyester resin may be used in combination with a crystalline polyester resin. However, the content of the crystalline polyester resin is preferably in the range of 2% by mass to 40% by mass (preferably 2% by mass to 20% by mass) relative to the total binder resin.

[0092] The "crystalline" nature of a resin refers to the presence of a clear endothermic peak rather than a stepwise change in endothermic heat in differential scanning calorimetry (DSC). Specifically, this refers to the half-width of the endothermic peak being within 10°C when measured at a heating rate of 10°C / min. On the other hand, the term "amorphous" for a resin means that the half-width exceeds 10°C, that the endothermic amount exhibits a stepwise change, or that no clear endothermic peak is observed.

[0093] Amorphous polyester resin Examples of the amorphous polyester resin include a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. Note that, as the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0094] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acids may be used alone or in combination of two or more.

[0095] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, preferred polyhydric alcohols are aromatic diols and alicyclic diols, and more preferred are aromatic diols. As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0096] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0097] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurements by GPC are performed using a Tosoh GPC HLC-8120GPC measuring device and a Tosoh TSKgel SuperHM-M (15 cm) column in THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0098] The amorphous polyester resin can be obtained by a known manufacturing method, for example, by carrying out the reaction at a polymerization temperature of 180°C or higher and 230°C or lower, reducing the pressure in the reaction system as necessary, and removing water and alcohol generated during the condensation. If the raw material monomers are not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, it is advisable to first condense the poorly compatible monomer with the acid or alcohol to be polycondensed, and then polycondense it with the main component.

[0099] Crystalline polyester resin The crystalline polyester resin may be, for example, a polycondensate of a polycarboxylic acid and a polyhydric alcohol. Note that, as the crystalline polyester resin, a commercially available product or a synthesized product may be used. Here, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group, since it easily forms a crystalline structure.

[0100] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acid may be a tricarboxylic or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the tricarboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polycarboxylic acids may be used alone or in combination of two or more.

[0101] Examples of polyhydric alcohols include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. The polyhydric alcohol may be a trihydric or higher alcohol having a crosslinked or branched structure, such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol, in combination with the diol. The polyhydric alcohols may be used alone or in combination of two or more.

[0102] Here, the polyhydric alcohol has an aliphatic diol content of 80 mol % or more, preferably 90 mol % or more.

[0103] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121-1987 "Method for measuring transition temperatures of plastics."

[0104] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0105] The crystalline polyester resin can be obtained by a known manufacturing method, for example, in the same manner as the amorphous polyester.

[0106] Here, the binder resin may be used in combination with the polyester resin, and a preferred example of the other binder resin is a styrene (meth)acrylic resin.

[0107] Styrene (meth)acrylic resin is a copolymer obtained by copolymerizing at least a monomer having a styrene skeleton and a monomer having a (meth)acryloyl group. "(Meth)acrylic acid" is an expression that includes both "acrylic acid" and "methacrylic acid." Furthermore, "(meth)acryloyl group" is an expression that includes both "acryloyl group" and "methacryloyl group."

[0108] Examples of monomers having a styrene skeleton (hereinafter referred to as "styrene-based monomers") include styrene, alkyl-substituted styrenes (e.g., α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrenes (e.g., 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, etc. The styrene-based monomers may be used alone or in combination of two or more. Of these, styrene is preferred as the styrene-based monomer in terms of ease of reaction, ease of reaction control, and availability.

[0109] Examples of the monomer having a (meth)acryloyl group (hereinafter referred to as "(meth)acrylic monomer") include (meth)acrylic acid and (meth)acrylic acid esters. Examples of the (meth)acrylic acid ester include (meth)acrylic acid alkyl esters (e.g., n-methyl (meth)acrylate, n-ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, amyl (meth)acrylate, Examples of (meth)acrylic acid monomers include neopentyl acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, etc.), (meth)acrylic acid aryl esters (for example, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, t-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, etc.), dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, β-carboxyethyl (meth)acrylate, and (meth)acrylamide. One (meth)acrylic acid monomer may be used alone, or two or more may be used in combination.

[0110] The copolymerization ratio of the styrene-based monomer to the (meth)acrylic monomer (based on mass, styrene-based monomer / (meth)acrylic monomer) may be, for example, 85 / 15 to 70 / 30.

[0111] The styrene (meth)acrylic resin preferably has a crosslinked structure in order to suppress image offset. Examples of the styrene (meth)acrylic resin having a crosslinked structure include a crosslinked product obtained by copolymerizing at least a monomer having a styrene skeleton, a monomer having a (meth)acrylic acid skeleton, and a crosslinkable monomer.

[0112] Examples of the crosslinkable monomer include bifunctional or higher functional crosslinking agents. Examples of bifunctional crosslinking agents include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylene bis(meth)acrylamide, decanediol diacrylate, glycidyl (meth)acrylate, etc.), polyester-type di(meth)acrylate, 2-([1'-methylpropylideneamino]carboxyamino)ethyl methacrylate, etc. Examples of polyfunctional crosslinking agents include tri(meth)acrylate compounds (e.g., pentaerythritol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.), tetra(meth)acrylate compounds (e.g., tetramethylolmethane tetra(meth)acrylate, oligoester (meth)acrylate, etc.), 2,2-bis(4-methacryloxy, polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl associanurate, triallyl isocyanurate, triallyl trimellitate, and diallyl chlorendate.

[0113] The copolymerization ratio of the crosslinkable monomer to the total monomers (based on mass, crosslinkable monomer / total monomers) may be, for example, 2 / 1000 to 30 / 1000.

[0114] The weight average molecular weight of the styrene (meth)acrylic resin is, for example, from 30,000 to 200,000, preferably from 40,000 to 100,000, and more preferably from 50,000 to 80,000, in terms of suppressing image offset. The weight average molecular weight of the styrene (meth)acrylic resin is a value measured by the same method as that for the weight average molecular weight of the polyester resin.

[0115] The content of the styrene (meth)acrylic resin is, for example, from 10% by mass to 30% by mass, preferably from 12% by mass to 28% by mass, and more preferably from 15% by mass to 25% by mass, relative to the toner particles, in order to achieve both the fluidity and storage stability of the toner and the suppression of image offset.

[0116] Furthermore, other binder resins may be used in combination as the binder resin. Other binder resins include, for example, homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or vinyl resins made of copolymers of two or more of these monomers. Examples of other binder resins include non-vinyl resins such as epoxy resins, polyester resins, polyurethanes, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These other binder resins may be used alone or in combination of two or more.

[0117] The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, based on the total mass of the toner particles.

[0118] --Colorant-- Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and the like. Examples of the dyes include various pigments such as phosphorus blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and various dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0119] The colorant may be surface-treated as needed, or may be used in combination with a dispersant. Furthermore, a plurality of colorants may be used in combination.

[0120] The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0121] -Other additives- Examples of other additives in the toner include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0122] -Characteristics of toner particles- The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core, and the core-shell structure is preferred. The toner particles of the core-shell structure are preferably composed of, for example, a core composed of a binder resin and a colorant, and a coating layer composed of a binder resin and a release agent.

[0123] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0124] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5 mass % aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute, and the particle size distribution of particles in the range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v and number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v and number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

[0125] The shape factor SF1 of the toner particles is preferably 110 or more and 150 or less, and more preferably 120 or more and 140 or less.

[0126] The shape factor SF1 is calculated by the following formula. Formula: SF1=(ML 2 / A)×(π / 4)×100 In the above formula, ML represents the absolute maximum length of the toner, and A represents the projected area of ​​the toner. Specifically, the shape factor SF1 is quantified by analyzing mainly microscopic or scanning electron microscopic images using an image analyzer, and is calculated as follows: That is, optical microscopic images of particles scattered on the surface of a glass slide are captured by a video camera into a Luzex image analyzer, the maximum length and projected area of ​​100 particles are determined, and the average value is calculated using the above formula.

[0127] -External additives- The toner may further contain an external additive in addition to the toner particles. Examples of external additives include inorganic particles such as SiO2, TiO2, Al2O3, SrTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, KO, Na2O, ZrO2, CaO·SiO2, KO·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0128] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

[0129] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0130] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles.

[0131] -Toner manufacturing method- The toner is produced by producing toner particles and, if an external additive is further contained, externally adding the external additive to the toner particles.

[0132] The toner particles may be produced by any of a dry production method (for example, a kneading and pulverization method) and a wet production method (for example, an aggregation and coalescence method, a suspension polymerization method, a dissolution and suspension method). There are no particular limitations on these production methods, and well-known production methods may be used. Among these, it is preferable to obtain toner particles by an aggregation and coalescence method.

[0133] Each step of the aggregation-coalescence method will be described in detail below. In the following description, a method for obtaining toner particles containing a colorant will be described, but the colorant is used as needed. Of course, other additives besides the colorant may also be used.

[0134] ·Resin particle dispersion preparation process First, a resin particle dispersion liquid in which resin particles serving as a binder resin are dispersed, a colorant dispersion liquid in which colorant particles are dispersed, and a release agent particle dispersion liquid in which release agent particles are dispersed are prepared.

[0135] The resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0136] Examples of the dispersion medium used in the resin particle dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water; alcohols; etc. These may be used alone or in combination of two or more.

[0137] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0138] Methods for dispersing resin particles in a dispersion medium include, for example, common dispersion methods using a rotary shear homogenizer, a ball mill with media, a sand mill, a Dynomill, etc. Alternatively, resin particles may be dispersed in a dispersion medium by a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then adding water (W phase) to invert the phase from W / O to O / W, thereby dispersing the resin in particulate form in an aqueous medium.

[0139] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm. The volume average particle size of the resin particles is determined by plotting the cumulative volume distribution for each divided particle size range (channel) from the smallest particle size side using a particle size distribution obtained by measurement using a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and determining the particle size that accounts for 50% of the total particle volume as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same way.

[0140] The content of resin particles contained in the resin particle dispersion is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0141] The colorant dispersion and the release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. That is, the dispersion medium, dispersion method, particle volume average particle size, and particle content in the resin particle dispersion are the same for the colorant dispersion and the release agent particle dispersion.

[0142] ·First agglomerated particle formation step Next, the resin particle dispersion and the colorant dispersion are mixed. Then, in the mixed dispersion, the resin particles and the colorant particles are hetero-aggregated to form first aggregated particles containing the resin particles and the colorant particles and having a diameter close to that of the target toner particles. If necessary, a release agent particle dispersion may also be mixed to make the first aggregated particles contain release agent particles.

[0143] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 or higher and 5 or lower), and a dispersion stabilizer is added as necessary.Then, the mixed dispersion is heated to a temperature close to the glass transition temperature of the resin (specifically, for example, −30° C. or higher and −10° C. or lower than the glass transition temperature of the resin), and the particles dispersed in the mixed dispersion are aggregated to form first aggregated particles. In the first aggregate particle formation step, for example, the mixed dispersion may be stirred with a rotary shear homogenizer, an aggregating agent may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), a dispersion stabilizer may be added as needed, and then the mixture may be heated.

[0144] Examples of the flocculant include a surfactant having an opposite polarity to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. When a metal complex is used as the flocculant, the amount of the flocculant used can be reduced, and the charging characteristics can be improved. An additive that forms a complex or a similar bond with the metal ions of the flocculant may be used together with the flocculant, and a chelating agent is preferably used as this additive.

[0145] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, for example, hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA); and the like. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the resin particles.

[0146] ·Second agglomerated particle formation process After obtaining the first aggregated particle dispersion in which the first aggregated particles are dispersed, the first aggregated particle dispersion, the resin particle dispersion, and the release agent particle dispersion are further mixed. The resin particle dispersion and the release agent particle dispersion may be mixed in advance, and the mixture may be mixed with the first aggregated particle dispersion.

[0147] Then, in the mixed dispersion in which the first aggregated particles, resin particles, and release agent particles are dispersed, the resin particles and release agent particles are aggregated so as to adhere to the surfaces of the first aggregated particles, thereby forming second aggregated particles.

[0148] Specifically, for example, in the first aggregate particle formation step, when the first aggregate particles reach a target particle size, a dispersion of resin particles and release agent particles is mixed with the first aggregate particle dispersion, and then the mixed dispersion is heated to a temperature below the glass transition temperature of the resin, and the pH of the mixed dispersion is adjusted to, for example, a range of about 6.5 to 8.5 to stop the aggregation.

[0149] As a result, second aggregated particles are obtained, which are aggregated so that the resin particles and the release agent particles adhere to the surfaces of the first aggregated particles.

[0150] ·Fusion / coalescence process Next, the second aggregate particle dispersion liquid in which the second aggregate particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin (for example, a temperature 10°C to 50°C higher than the glass transition temperature of the resin), to fuse and coalesce the second aggregate particles and form toner particles.

[0151] Through the above steps, toner particles are obtained. After obtaining the second aggregate particle dispersion liquid in which the second aggregate particles are dispersed, the toner particles may be produced through the following steps: a step of further mixing the second aggregate particle dispersion liquid with a resin particle dispersion liquid in which resin particles are dispersed, and aggregating the second aggregate particles so that the resin particles adhere to the surfaces of the second aggregate particles to form third aggregate particles; and a step of heating the third aggregate particle dispersion liquid in which the third aggregate particles are dispersed to fuse and coalesce the third aggregate particles to form toner particles.

[0152] After the fusion and coalescence process is completed, the toner particles formed in the solution are subjected to a known washing process, solid-liquid separation process, and drying process to obtain dry toner particles. In the washing step, from the viewpoint of chargeability, it is preferable to carry out sufficient replacement washing with ion-exchanged water. Furthermore, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out suction filtration, pressure filtration, etc. Furthermore, in the drying step, there is no particular limitation on the method, but from the viewpoint of productivity, it is preferable to carry out freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0153] The toner according to this embodiment is produced by, for example, adding external additives to dry toner particles and mixing them. The mixing can be carried out using, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, or the like.

[0154] -Career- The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin.

[0155] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0156] Examples of coating resins and matrix resins include styrene-(meth)acrylic acid resins; polyolefin resins such as polyethylene resins and polypropylene resins; polyvinyl or polyvinylidene resins such as polystyrene, (meth)acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymers; straight silicone resins or modified silicone resins consisting of organosiloxane bonds; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; and epoxy resins. The coating resin and the matrix resin preferably contain a (meth)acrylic resin, more preferably contain 50% by mass or more of the (meth)acrylic resin relative to the total mass of the resin, and even more preferably contain 80% by mass or more of the (meth)acrylic resin relative to the total mass of the resin. In particular, the coating resin and the matrix resin preferably contain an alicyclic (meth)acrylic resin as the (meth)acrylic resin. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0157] Here, the method of coating the surface of the core material with a coating resin includes a method of coating with a solution for forming a coating layer in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, its applicability, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0158] In the two-component developer, the mixing ratio (mass ratio) of toner to carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0159] (Intermediate transfer type transfer device) - Primary transfer device - In the primary transfer device, the primary transfer member is disposed opposite to the image carrier with the intermediate transfer member sandwiched therebetween. In the primary transfer device, the primary transfer member applies a voltage of a polarity opposite to the charge polarity of the toner to the intermediate transfer member, thereby primarily transferring the toner image onto the outer peripheral surface of the intermediate transfer member.

[0160] -Secondary transfer device- In the secondary transfer device, the secondary transfer member is disposed on the toner image bearing side of the intermediate transfer body. The secondary transfer device includes, for example, a backing member disposed on the opposite side of the intermediate transfer body from the toner image bearing side, along with the secondary transfer member. In the secondary transfer device, the intermediate transfer body and the recording medium are sandwiched between the secondary transfer member and the backing member to form a transfer electric field, thereby secondarily transferring the toner image on the intermediate transfer body to the recording medium. The secondary transfer member may be a secondary transfer roll or a secondary transfer body. The backing member may be, for example, a backing roll.

[0161] -Other configurations of the transfer device- This embodiment may also be a transfer device that transfers a toner image onto the surface of a recording medium via multiple intermediate transfer bodies. That is, the transfer device may be a transfer device that, for example, performs primary transfer of a toner image from an image carrier to a first intermediate transfer body, then secondary transfers the toner image from the first intermediate transfer body to a second intermediate transfer body, and then tertiary transfers the toner image from the second intermediate transfer body to a recording medium.

[0162] (Configuration of image forming device) An example of an image forming apparatus according to the present embodiment will be described below 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 descriptions of other parts will be omitted.

[0163] FIG. 1 is a schematic diagram showing an example of the configuration of an image forming apparatus according to the present embodiment. 1, image forming apparatus 100 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 device) that form toner images of each color component by electrophotography, a primary transfer unit 10 that sequentially transfers (primary transfer) the toner images of each color component formed by each image forming unit 1Y, 1M, 1C, and 1K onto an intermediate transfer belt 15, a secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner images transferred onto intermediate transfer belt 15 onto paper K, which is a recording medium, and a fixing device 60 that fixes the secondarily transferred image onto paper K. Image forming apparatus 100 also has a control unit 40 that controls the operation of each device (each unit).

[0164] 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.

[0165] Around the photosensitive member 11, there is provided a charger 12 as an example of a charging means for charging the photosensitive member 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 photosensitive member 11.

[0166] In addition, around the photosensitive member 11, there is provided a developing device 14 as an example of a developing means, which contains toner of each color component and makes the electrostatic latent image on the photosensitive member 11 visible using the toner, and there is provided a primary transfer roll 16 which transfers the toner image of each color component formed on the photosensitive member 11 to an intermediate transfer belt 15 at the primary transfer section 10.

[0167] Furthermore, a photoreceptor cleaner 17 is provided around the photoreceptor 11 to remove residual toner from the photoreceptor 11, and electrophotographic devices including a charger 12, a laser exposure device 13, a developing device 14, a primary transfer roll 16, and the photoreceptor cleaner 17 are arranged in this order along the rotation direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially linear fashion from the upstream side of the intermediate transfer belt 15 in the order of yellow (Y), magenta (M), cyan (C), and black (K).

[0168] The intermediate transfer belt 15 is driven (rotated) in a circular manner (in the direction of arrow B shown in Fig. 1) by various rolls at a speed suited to the purpose. These rolls include a drive roll 31 driven by a motor (not shown) with excellent constant speed characteristics to rotate the intermediate transfer belt 15, a support roll 32 that supports the intermediate transfer belt 15, which extends 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 opposite an intermediate transfer belt cleaning blade 35 that scrapes off residual toner on the intermediate transfer belt 15.

[0169] The primary transfer unit 10 is composed of a primary transfer roll 16 disposed opposite the photoconductor 11 with the intermediate transfer belt 15 sandwiched therebetween. The primary transfer roll 16 is disposed 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.

[0170] The secondary transfer unit 20 is configured to include 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 .

[0171] The back roll 25 has a surface resistivity of 1 x 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 hereinafter.) The back roll 25 is disposed on the back side of the intermediate transfer belt 15 and constitutes an opposing electrode of the secondary transfer roll 22, and is in contact with a metal power supply roll 26 to which a secondary transfer bias is stably applied.

[0172] 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 grounded to form a secondary transfer bias between the secondary transfer roll 22 and the back roll 25, thereby performing a second transfer of the toner image onto the paper K being transported to the secondary transfer unit 20.

[0173] In addition, an intermediate transfer belt cleaning blade 35 is provided on the downstream side of the secondary transfer section 20 of the intermediate transfer belt 15 so as to be freely movable toward and away from the intermediate transfer belt 15, removing residual toner and paper dust from the intermediate transfer belt 15 after the secondary transfer and cleaning the outer surface of the intermediate transfer belt 15. Further, downstream of the secondary transfer portion 20 of the secondary transfer roll 22, a secondary transfer roll 23 is provided. A secondary transfer roll cleaning member 22A is provided to remove residual toner and paper dust from the roll 22 and clean the outer peripheral surface of the intermediate transfer belt 15. The secondary transfer roll cleaning member 22A is exemplified by a cleaning blade, but may also be a cleaning roll.

[0174] The intermediate transfer belt 15, the primary transfer roll 16, the secondary transfer roll 22, and the intermediate transfer belt cleaning member 35 correspond 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.

[0175] Meanwhile, a reference sensor (home position sensor) 42 is disposed upstream of the yellow image forming unit 1Y, generating 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.

[0176] Furthermore, the image forming apparatus according to this embodiment is equipped with a transport means for transporting paper K, which includes a paper storage section 50 for storing paper K, a paper feed roll 51 for taking out and transporting paper K accumulated in the paper storage section 50 at a predetermined timing, a transport roll 52 for transporting paper K unwound by the paper feed roll 51, a transport guide 53 for sending paper K transported by the transport roll 52 to the secondary transfer section 20, a transport belt 55 for transporting paper K transported after secondary transfer by the secondary transfer roll 22 to the fixing device 60, and a fixing entrance guide 56 for guiding paper K to the fixing device 60.

[0177] Next, the basic image forming process, that is, the image forming method, of the image forming apparatus according to this embodiment will be described. In the image forming apparatus according to this embodiment, image data output from an image reading device (not shown) or a personal computer (PC) (not shown) is 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.

[0178] 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 operations such as frame erasure, color editing, and movement editing. The image data that has undergone image processing is converted into color material gradation data for four colors, Y, M, C, and K, and is output to the laser exposure device 13.

[0179] In accordance with the input color material gradation data, the laser exposure device 13 irradiates the photoconductor 11 of each of the image forming units 1Y, 1M, 1C, and 1K with an exposure beam Bm emitted from, for example, a semiconductor laser. After the surface of the photoconductor 11 of each of the image forming units 1Y, 1M, 1C, and 1K is charged by the charger 12, the surface is scanned and exposed by the laser exposure 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.

[0180] The toner images formed on the photosensitive members 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 photosensitive member 11 and the intermediate transfer belt 15 come into contact with each other. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) of a polarity opposite to the charge 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 outer circumferential surface of the intermediate transfer belt 15. The primary transfer is performed in combination with the image.

[0181] After the toner images are sequentially primarily transferred onto the outer peripheral surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves, and the toner images are transported 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 synchronization 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 a positioning roll (not shown) rotates in synchronization with the movement 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.

[0182] In the secondary transfer unit 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 conveyed 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 charge polarity (negative polarity) of the toner is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the back roll 25. Then, the unfixed toner images held on the intermediate transfer belt 15 are electrostatically transferred onto the paper K all at once in the secondary transfer unit 20, which is pressed by the secondary transfer roll 22 and the back roll 25.

[0183] Thereafter, the paper sheet K onto which the toner image has been electrostatically transferred is transported as 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 sheet K to the fixing device 60 at an optimal transport speed for the fixing device 60. The unfixed toner image on the paper sheet K transported to the fixing device 60 is fixed onto the paper sheet K by being subjected to a fixing process using heat and pressure by the fixing device 60. The paper sheet K on which the fixed image has been formed is then transported to an ejected paper storage unit (not shown) provided in the ejection unit of the image forming apparatus.

[0184] 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 intermediate transfer belt cleaning blade 35 as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the intermediate transfer belt cleaning blade 35.

[0185] Although the present embodiment has been described above, it should not be construed as being limited to the above embodiment, and various modifications, changes, and improvements are possible. [Example]

[0186] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples. In the following description, unless otherwise specified, all "parts" and "%" are by mass.

[0187] Example 1 <Preparation of Electrostatic Image Developer> -Preparation of amorphous polyester resin dispersion- (Preparation of amorphous polyester resin dispersion (APE1)) Terephthalic acid: 30 parts by mole Fumaric acid: 70 parts by mole Bisphenol A ethylene oxide adduct: 5 parts by mole Bisphenol A propylene oxide adduct: 95 parts by mole A 5-liter flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a rectification column The above materials were charged into a flask, the temperature was raised to 210°C over 1 hour, and 1 part of titanium tetraethoxide was added for every 100 parts of the above materials. The temperature was raised to 230°C over 0.5 hours while distilling off the water produced, and the dehydration condensation reaction was continued at that temperature for 1 hour, after which the reaction mixture was cooled. In this way, a polyester resin with a weight-average molecular weight of 18,500, an acid value of 14 mgKOH / g, and a glass transition temperature of 59°C was synthesized.

[0188] 40 parts of ethyl acetate and 25 parts of 2-butanol were added to a container equipped with a temperature control means and a nitrogen substitution means to prepare a mixed solvent, and then 100 parts of polyester resin was gradually added and dissolved therein. Then, a 10% by mass aqueous ammonia solution (equivalent to three times the molar amount of the acid value of the resin) was added thereto and stirred for 30 minutes. Next, the atmosphere inside the vessel was replaced with dry nitrogen, the temperature was maintained at 40°C, and 400 parts of ion-exchanged water was added dropwise at a rate of 2 parts / min while stirring the mixture, thereby emulsifying it. After the addition was completed, the emulsion was returned to room temperature (20°C to 25°C), and dry nitrogen was bubbled through the mixture for 48 hours while stirring, reducing the ethyl acetate and 2-butanol concentrations to 1,000 ppm or less, yielding a resin particle dispersion containing dispersed resin particles with a volume average particle size of 200 nm. Ion-exchanged water was added to the resin particle dispersion to adjust the solids content to 20% by mass, resulting in a polyester resin particle dispersion (APE1). -Preparation of crystalline resin particle dispersion- (Preparation of Crystalline Polyester Resin Dispersion (CPE1)) 1,10-dodecanedioic acid: 225 parts 1,6-Hexanediol: 143 parts The above materials were charged into a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column. The temperature was raised to 160°C over 1 hour, and 0.8 parts by mass of dibutyltin oxide was added. The temperature was raised to 180°C over 6 hours while distilling off the produced water, and the dehydration condensation reaction was continued for 5 hours while maintaining the temperature at 180°C. The temperature was then gradually raised to 230°C under reduced pressure, and stirring was continued for 2 hours while maintaining the temperature at 230°C. The reaction product was then cooled. After cooling, solid-liquid separation was performed, and the solid was dried to obtain a crystalline polyester resin.

[0189] Crystalline polyester resin: 100 parts Methyl ethyl ketone: 40 parts Isopropyl alcohol: 30 parts 10% ammonia solution: 6 parts The above materials were added to a 3-liter jacketed reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dripper, and anchor blades. The resin was dissolved by stirring at 100 rpm while maintaining the temperature at 80°C in a water-circulating thermostatic bath. The water-circulating thermostatic bath was then set to 50°C, and a total of 400 parts of ion-exchanged water maintained at 50°C was added dropwise at a rate of 7 parts by mass / min to induce phase inversion, yielding an emulsion. 576 parts by mass of the resulting emulsion and 500 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. The recovery flask was heated in a 60°C hot water bath while rotating, and the pressure was reduced to 7 kPa, taking care to avoid bumping, to remove the solvent. The volume-average particle diameter (D50v) of the resin particles in this dispersion was 185 nm. Thereafter, ion-exchanged water was added to obtain a crystalline resin particle dispersion (CPE1) with a solid content concentration of 22.1% by mass.

[0190] -Preparation of colorant particle dispersion- (Preparation of Colorant Particle Dispersion (Black Pigment Dispersion)) Carbon black (Cabot, Regal 330): 250 parts Anionic surfactant (NEOGEN SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 33 parts (active ingredient 60%, colorant 8%) Ion-exchanged water: 750 parts 280 parts of ion-exchanged water and 33 parts of anionic surfactant were placed in a stainless steel container large enough that the liquid level would be approximately 1 / 3 of the container's height when all of the above ingredients were added. After thoroughly dissolving the surfactant, all of the solid solution pigment was added and stirred using a stirrer until no unwetted pigment remained, and the mixture was thoroughly degassed. After degassing, the remaining ion-exchanged water was added, and the mixture was dispersed at 5,000 rpm for 10 minutes using a homogenizer (IKA Ultra Turrax T50), followed by stirring overnight with a stirrer for degassing. After degassing, the mixture was again dispersed at 6,000 rpm for 10 minutes using a homogenizer, followed by stirring overnight with a stirrer for degassing. The dispersion was then dispersed at a pressure of 240 MPa using a high-pressure impact disperser, Ultimizer (Sugino Machine Co., Ltd., HJP30006). The dispersion was performed for a total of 25 passes, calculated based on the total amount charged and the processing capacity of the equipment. The resulting dispersion was left to stand for 72 hours to remove the precipitate, and ion-exchanged water was added to adjust the solids concentration to 15%, yielding a colorant particle dispersion. The volume average particle diameter D50 of the particles in this colorant particle dispersion was 135 nm.

[0191] -Preparation of release agent dispersion- (Preparation of release agent dispersion (WAX1)) Paraffin wax (HNP9 manufactured by Nippon Seiro, melting point 75°C): 270 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK, active ingredient amount: 60%): 13.5 parts (active ingredient, 3.0% of the release agent) Ion-exchanged water: 21.6 parts The above components were mixed and the release agent was dissolved in a pressure discharge homogenizer (Gaulin Homogenizer, manufactured by Gaulin Co., Ltd.) at an internal liquid temperature of 120°C. The mixture was then dispersed at a dispersion pressure of 5 MPa for 120 minutes, then at 40 MPa for 360 minutes, and cooled to obtain a release agent dispersion (WAX1). The volume average particle size D50 of the particles in this release agent dispersion (WAX1) was 225 nm. Ion-exchange water was then added to adjust the solids concentration to 20.0%.

[0192] -Preparation of mixed particle dispersion- (Preparation of mixed particle dispersion (RW1)) 150 parts of polyester resin particle dispersion (APE1), 20 parts of release agent particle dispersion (WAX1), and 2.9 parts of anionic surfactant (Dowfax2A1 manufactured by The Dow Chemical Company) were mixed, and then 1.0% nitric acid was added at 25°C to adjust the pH to 3.0, thereby obtaining a mixed particle dispersion (RW1).

[0193] - Toner preparation - Polyester resin particle dispersion (APE1): 600 parts ·Crystalline resin particle dispersion (CPE1): 120 parts Colorant particle dispersion: 133 parts Ion-exchanged water: 400 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 2.9 parts The above components were placed in a 3-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and 1.0% nitric acid was added at 25°C to adjust the pH to 3.0. The mixture was then dispersed at 5,000 rpm using a homogenizer (Ultra Turrax T50, manufactured by IKA Japan Co., Ltd.), while 130 parts of the prepared aqueous aluminum sulfate solution was added and dispersed for 6 minutes.

[0194] The reaction vessel was then equipped with a stirrer and mantle heater. The stirrer rotation speed was adjusted to ensure sufficient stirring of the slurry. The temperature was increased at a rate of 0.2°C / min up to 40°C, and then at a rate of 0.05°C / min after exceeding 40°C. Particle size was measured every 10 minutes using a Multisizer II (aperture diameter: 50 μm, manufactured by Coulter). When the volume average particle size reached 5.0 μm, the temperature was maintained, and 450 parts of the mixed particle dispersion (RW1) were added over 5 minutes. After a 30-minute hold, the pH was adjusted to 9.0 using a 1% aqueous sodium hydroxide solution. The temperature was then increased to 85°C at a rate of 1°C / min and maintained at that temperature, while adjusting the pH to 9.0 every 5°C. Particle shape and surface properties were observed using an optical microscope and a scanning electron microscope (FE-SEM). After 5.0 hours, particle coalescence was confirmed, and the vessel was cooled to 30°C over 5 minutes using cooling water.

[0195] After cooling, the slurry was passed through a 15 μm nylon mesh to remove coarse particles. The toner slurry that passed through the mesh was filtered under reduced pressure using an aspirator. The toner remaining on the filter paper was crushed by hand and added to ion-exchanged water (10 times the toner volume) at 30°C, followed by stirring and mixing for 30 minutes. The mixture was then filtered under reduced pressure using an aspirator. The toner remaining on the filter paper was crushed by hand and added to ion-exchanged water (10 times the toner volume) at 30°C, followed by stirring and mixing for 30 minutes. The mixture was then filtered under reduced pressure using an aspirator again, and the electrical conductivity of the filtrate was measured. This process was repeated until the electrical conductivity of the filtrate reached 10 μS / cm or less, and the toner was then washed. The washed toner was crushed using a wet-dry granulator (Comil) and vacuum-dried in an oven at 35°C for 36 hours to obtain toner particles.

[0196] Then, 3.3 parts of silica particles were added as an external additive to 100 parts of the toner particles. The mixture was then mixed for 3 minutes at a peripheral speed of 30 m / s using a Henschel mixer. The mixture was then sieved using a vibrating sieve with 45 μm openings to obtain a toner.

[0197] -Creating a carrier- 500 parts of spherical magnetite particle powder having a volume average particle size of 0.18 μm was charged into a Henschel mixer and thoroughly stirred, after which 5 parts of a titanate coupling agent was added, the mixture was heated to 95°C, and mixed and stirred for 30 minutes to obtain spherical magnetite particles coated with a titanate coupling agent. Next, 6 parts of phenol, 10 parts of 30% formalin, 500 parts of magnetite particles, 7 parts of 25% aqueous ammonia, and 400 parts of water were placed in a 1 L four-neck flask and mixed with stirring. Next, the mixture was heated to 90°C over 60 minutes while stirring, and reacted at the same temperature for 180 minutes. After cooling to 30°C and adding 500 ml of water, the supernatant was removed and the precipitate was washed with water. This was dried at 180°C under reduced pressure and then passed through a sieve with 106 μm openings to remove coarse particles, yielding core particles with an average particle size of 38 μm. Next, 200 parts of toluene and 35 parts of a styrene-methyl methacrylate copolymer (component molar ratio 10:90, weight average molecular weight 160,000) were stirred with a stirrer for 90 minutes to obtain a coating resin solution. 1,000 parts of core particles and 70 parts of coating resin solution were placed in a vacuum degassing kneader coater (rotor-wall clearance 35 mm) and stirred at 30 rpm for 30 minutes while maintaining the temperature at 65°C. After that, the temperature was lowered to 88°C, and the pressure was reduced to remove toluene, degass, and dry. The mixture was then passed through a 75 μm mesh. The carrier shape factor SF2 was 104.

[0198] - Developer production - 8 parts of the toner and 100 parts of the carrier were mixed in a V blender to prepare a developer.

[0199] - Toner physical properties - The ratio of the release agent present within 800 nm from the surface of the toner particles to the release agent of the entire toner particle (surface layer ratio of the release agent) was measured by the above-mentioned method. Also, the melting temperature of the release agent was measured by the above-mentioned method.

[0200] <Cleaning Blade Production> Polycaprolactone polyol (Daicel Corporation, PLACCEL 205) and polycaprolactone polyol (Daicel Corporation, PLACCEL 240) were used as the hard segment materials of the polyol component. An acrylic resin containing two or more hydroxy groups (Soken Chemical & Engineering Co., Ltd., Actflow UMB-2005B) was used as the soft segment material. The hard segment material and soft segment material were mixed in a mass ratio of 8:2. Next, 40 parts of silica particles were added to 100 parts of this mixture of hard segment material and soft segment material, and then 4,4'-diphenylmethane diisocyanate (Millionate MT, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as an isocyanate compound and reacted at 70°C for 3 hours under a nitrogen atmosphere. Subsequently, the above isocyanate compound was further added, and the mixture was reacted at 70°C for 3 hours under a nitrogen atmosphere to obtain a prepolymer. Next, this prepolymer was heated to 100°C and degassed under reduced pressure for 1 hour. After that, a mixture of 1,4-butanediol and trimethylolpropane was added to the prepolymer and mixed for 3 minutes to prevent air bubbles from being introduced. The mixture was then poured into a centrifugal molding machine and allowed to cure. It was then cut into a length of 15 mm and a thickness of 2 mm to obtain a cleaning blade precursor.

[0201] ·Contact area modification treatment The contact portion of the edge layer of the obtained cleaning blade precursor with the intermediate transfer belt was subjected to a surface modification treatment using a silicone polymer as follows. The silicone polymer used was Modiper FS770 manufactured by NOF Corporation. The surface modification treatment was carried out by immersing the cleaning blade precursor in a surface treatment liquid prepared by dispersing and mixing 20 parts of 4,4'-diphenylmethane diisocyanate (4,4-MDI) and 2 parts of a silicone polymer in 100 parts of methyl ethyl ketone (MEK) for 3 hours in a ball mill, and then removing it and drying it in an oven at 50°C.

[0202] By the above operation, a cleaning blade having a length of 15 mm and a thickness of 2 mm, the surface of which was modified at the contact portion with the intermediate transfer belt, was obtained.

[0203] -Cleaning blade physical properties- The following physical properties of the cleaning blade were measured by the methods described above. Hardness of the blade contact area Plastic deformation power of the blade contact area The amount of silicon on the surface of the blade contact area XA The amount of Si at a depth of 50 nm from the surface of the blade contact area, XB

[0204] <Production of intermediate transfer belt> Carbon black particles were dispersed in a polyamic acid solution to prepare coating solution 1. The coating solution was applied to a cylindrical mold to form a coating film, which was then dried. (Substrate 1) Thereafter, another carbon black particle was dispersed in the polyamic acid solution to prepare a coating liquid 2, which was then applied onto the substrate 1 and dried. After that, the substrate was subjected to a baking step and then cut. Through the above operations, a polyimide intermediate transfer belt was obtained.

[0205] <Image forming device> Image forming equipment "Fujifilm Business Innovation Co., Ltd. Apeosport-VI The electrostatic image developer, the intermediate transfer belt, and the cleaning blade for the intermediate transfer belt obtained above were attached to the "C7771". The mounting conditions for the cleaning blade for the intermediate transfer belt were set such that the pressing pressure NF (Normal Force, gf / mm) was the condition shown in Table 1, and the angle W / A (Working Angle) was 10°.

[0206] [Examples 2 to 11, Comparative Examples 1 to 6] <Preparation of Electrostatic Image Developer> In Example 1, the release agent used in preparing the release agent dispersion was selected, and the amount of the mixed particle dispersion (RW1) used in preparing the toner was adjusted to prepare toner particles that satisfied the "surface layer ratio (%) of the release agent" and "melting temperature (°C) of the release agent" shown in Tables 1 and 2, and an electrostatic image developer was obtained. As the release agents having the melting temperatures shown in Table 1, the following were used alone or in combination. Paraffin wax (manufactured by Nippon Seiro Co., Ltd., melting temperature 64°C) Paraffin wax (HNP9 made by Nippon Seiro, melting point 75°C) Ester wax (NOF Corporation, melting temperature 82°C) A mixed wax of paraffin wax (manufactured by Nippon Seiro Co., Ltd., melting temperature 64°C) and paraffin wax (manufactured by Nippon Seiro HNP9, melting temperature 75°C) (the ratio of the waxes was adjusted to make the melting temperature 65°C) A mixed wax of paraffin wax (HNP9 manufactured by Nippon Seiro, melting temperature 75°C) and ester wax (manufactured by NOF Corporation, melting temperature 82°C) (the ratio of the waxes was adjusted to make the melting temperature 80°C)

[0207] <Cleaning Blade Production> In Example 1, cleaning blades having the above cleaning blade physical properties shown in Tables 1 and 2 were prepared by adjusting the ratio of hard segment to soft segment, the amount of silica particles, and the immersion time in the surface treatment liquid. The pressing pressure NF (gf / mm) when the obtained cleaning blade was attached to the image forming apparatus was set to the conditions shown in Table 1.

[0208] <Evaluation test> (Color streaks (toner slip-through)) The image forming apparatuses prepared in each example and comparative example were left in a high temperature and high humidity environment (28°C / 80%RH) for one day, and then 10,000 images with an image density of 1% were printed in the same environment, and the occurrence of color streaks was evaluated according to the following criteria: G3 and below were considered acceptable. G1: No occurrence G2: Color streaks appear between 8,000 and 10,000 sheets G3: Color streaks appear between 6000 and 7999 sheets G4: Color streaks appear between 4500 and 5999 sheets G5: Color streaks appear on up to 4499 sheets

[0209] (low temperature fixability) The image forming apparatus prepared in each example and comparative example had a toner loading of 0.45 mg / cm 2 An image of 50 mm x 50 mm with an image density of 100% was formed on an A4 size (basis weight 127 gsm) OS coated W paper manufactured by Fujifilm Business Innovation Co., Ltd. Fixing conditions: nip pressure 4.0 kgf / cm 2 The fixing temperature was 140°C. The resulting image was then folded, and the image quality was evaluated based on the degree of image loss at that portion. G1: No image defects were observed G2: Image defects were observed, but were minor. G3: Slight image defects were observed, but within acceptable limits G4: Image loss was observed

[0210] (Blade noise evaluation) The image forming apparatuses prepared in each Example and Comparative Example were left in a high temperature and high humidity environment (28°C / 80%RH) for one day, and then 100 images with an image density of 1% were printed in the same environment. The loudness of the abnormal noise generated by the vibration of the cleaning blade during this process was evaluated according to the following criteria. A rating of B was considered acceptable. A: Only the device operating sound can be heard. B: In addition to the device drive noise, the cleaning blade makes a slight noise. C: The cleaning blade is so noisy that anyone can hear it.

[0211] [Table 1]

[0212] From the above results, it can be seen that the image forming apparatus of this embodiment achieves low-temperature fixability and suppresses color streaks due to poor cleaning, compared to the image forming apparatus of the comparative example.

[0213] This embodiment includes the following aspects. (((1))) an electrostatic image developer containing a toner having toner particles, wherein a release agent present in a region within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particles, and the melting temperature of the release agent is 65°C or higher and 80°C or lower; a member to be cleaned; a cleaning blade that comes into contact with the outer peripheral surface of the member to be cleaned to clean the toner adhering to the surface of the member to be cleaned, the cleaning blade having a contact portion that comes into contact with the member to be cleaned, the contact portion containing polyurethane, having a hardness of 85° or more and 95° or less, a plastic deformation power of 12% or less, and a surface Si content of 15 atm % or more; An image forming apparatus comprising: (((2))) The image forming apparatus according to (((1))), wherein the plastic deformation power is 10% or less. (((3))) The image forming apparatus according to (((1))) or (((2))), wherein the amount of Si on the surface of the contact portion is 20 atm % or more. (((4))) The image forming apparatus according to any one of (((1))) to (((3))), wherein XB / XA is 0.8 or more, where XA is the amount of Si on the surface of the contact portion and XB is the amount of Si at a position 50 nm deep from the surface of the contact portion. (((5))) The image forming apparatus according to (((4))), wherein XB / XA is 0.9 or more. (((6))) The image forming apparatus according to any one of (((1))) to (((5)), wherein the contact portion contains a Si-containing compound. (((7))) The image forming apparatus according to any one of (((1))) to (((6))), wherein the cleaning blade contacts the member to be cleaned with a pressing pressure of 1.5 gf / mm or more and 4.5 gf / mm or less.

[0214] The effects of the above embodiment are as follows. According to the invention of (((1))) or (((6))), there is provided an image forming apparatus comprising: an electrostatic image developer containing a toner having toner particles, wherein the release agent present in a region within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particle, and the melting temperature of the release agent is 65°C or more and 80°C or less; a member to be cleaned; and a cleaning blade that comes into contact with the outer surface of the member to be cleaned and cleans the toner adhering to the surface of the member to be cleaned. In this image forming apparatus, the cleaning blade contains polyurethane at the contact portion that comes into contact with the member to be cleaned, and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%, thereby realizing low-temperature fixability and suppressing color streaks due to poor cleaning, compared to an image forming apparatus in which the cleaning blade has a contact portion that contains polyurethane and has a hardness of less than 85° or more than 95°, a plastic deformation power of more than 12%, or a surface Si content of less than 15 atm%. According to the invention related to (((2))), an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by poor cleaning, compared to when the plastic deformation power exceeds 10%. According to the invention (((3))), an image forming apparatus is provided which achieves low-temperature fixability while suppressing color streaks caused by poor cleaning, compared to when the Si content on the surface of the contact portion is less than 20 atm %. According to the invention related to (((4))), an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by poor cleaning, compared to when XB / XA is less than 0.8. According to the invention related to (((5))), an image forming apparatus is provided which realizes low-temperature fixability and suppresses color streaks caused by poor cleaning, compared to when XB / XA is less than 0.9.

[0215] According to the invention (((7))), an image forming apparatus is provided which achieves low-temperature fixability while suppressing color streaks caused by poor cleaning, compared to when the cleaning blade is in contact with the member to be cleaned at a pressing pressure of less than 1.5 gf / mm. [Explanation of symbols]

[0216] 1Y, 1M, 1C, 1K Image forming units 10 Primary transfer unit 11 Photoreceptor 12 Charger 13 Laser exposure device 14 Developer 15 Intermediate transfer belt 16 Primary transfer roll 17 Photoconductor cleaner 20 Secondary transfer unit 22 Secondary transfer roll 22A Secondary transfer roll cleaning member 25 Back Roll 26 Power supply roll 31 Drive Roll 32 Support Roll 33 Tensioning roll 34 Cleaning back roll 35 Intermediate transfer belt cleaning blade 40 Control Unit 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 100 Image forming device

Claims

1. an electrostatic image developer containing a toner having toner particles, wherein a release agent present in a region within 800 nm from the surface of the toner particles accounts for 70% or more of the release agent in the entire toner particles, and the melting temperature of the release agent is 65° C. or higher and 80° C. or lower; a member to be cleaned; a cleaning blade that comes into contact with the outer peripheral surface of the member to be cleaned to clean the toner adhering to the surface of the member to be cleaned, the cleaning blade having a contact portion that comes into contact with the member to be cleaned, the contact portion containing polyurethane, having a hardness of 85° or more and 95° or less, a plastic deformation power of 12% or less, and a surface Si content of 15 atomic % or more; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the plastic deformation power is 10% or less.

3. 2. The image forming apparatus according to claim 1, wherein the amount of Si on the surface of the contact portion is 20 atm % or more.

4. 2. The image forming apparatus according to claim 1, wherein XB / XA is 0.8 or more, where XA is the amount of Si on the surface of the contact portion and XB is the amount of Si at a position 50 nm deep from the surface of the contact portion.

5. 5. The image forming apparatus according to claim 4, wherein the ratio XB / XA is 0.9 or more.

6. The image forming apparatus according to claim 1 , wherein the contact portion contains a silicon-containing compound.

7. 2. The image forming apparatus according to claim 1, wherein the cleaning blade is in contact with the member to be cleaned with a pressing pressure of 1.5 gf / mm or more and 4.5 gf / mm or less.

Images