Process cartridge

Abstract

To provide a process cartridge which hardly generates a ghost and which prevents an image defect like a developer streak from occurring even in a long-term use, in a higher-speed printer than before.SOLUTION: In a process cartridge, a developing roller 25 has a surface moving in a direction opposite to a movement direction of a surface of a toner supply roller 34 at a position of contact with the toner supply roller 34. The developing roller 25 and the toner supply roller 34 rotate in a manner to have a peripheral speed ratio R of 1.1 or more and 2.5 or less, and toner to be used satisfies a predetermined regulation.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a process cartridge used in copying machines and printers that employ an electrophotographic or electrostatic recording system. [Background technology]

[0002] In an image forming apparatus such as a printer using an electrophotographic image forming method (electrophotographic process), an electrophotographic photoconductor (hereinafter referred to as "photoconductor") serving as an image carrier is uniformly charged, and the charged photoconductor is selectively exposed to light to form an electrostatic image on the photoconductor. The electrostatic image formed on the photoconductor is visualized as a toner image using toner as a developer. The toner image formed on the photoconductor is then transferred to a recording material such as recording paper or a plastic sheet, and the toner image transferred to the recording material is fixed to the recording material by applying heat or pressure, thereby recording an image. Such an image forming apparatus generally requires the supply of developer and the maintenance of various process means. In order to facilitate the supply of developer and the maintenance of various process means, a process cartridge has been put into practical use, in which a photoconductor, a charging means, a developing means, a cleaning means, etc. are integrated into a frame to form a cartridge that is detachably mountable to the main body of the image forming apparatus. The process cartridge system makes it possible to provide an image forming apparatus with excellent usability. In recent years, color image forming apparatuses that form color images using multiple color developers have become widespread. As color image forming apparatuses, so-called in-line type image forming apparatuses are known in which photoconductors corresponding to the respective image forming operations using multiple color developers are arranged in a line along the surface movement direction of a transfer target body to which a toner image is transferred. In-line type color image forming apparatuses include those in which multiple photoconductors are arranged in a line in a direction (for example, horizontal direction) that intersects with the vertical direction (gravity direction). The in-line type is a preferred image forming method in that it is easy to meet the demands for high-speed image formation and deployment to multifunction printers. Further, there is an image forming apparatus in which a photoconductor is disposed below an intermediate transfer body as a transfer recipient, or below a recording carrier that conveys a recording material as a transfer recipient (Patent Document 1). When the photoconductor is disposed below the intermediate transfer body or the recording material carrier, for example, the fixing device and the developing device (or the exposure device) can be disposed at positions separated from each other in the main body of the image forming apparatus with the intermediate transfer body or the recording material carrier sandwiched therebetween, which has the advantage that the developing device (or the exposure device) is less susceptible to the heat of the fixing device. In recent years, there has been an increasing demand for improved productivity, and printers capable of high-speed printing are in demand. As a cartridge configuration that enables high-speed printing, a cartridge configuration has been proposed in which a developing roller and a toner supply roller are brought into contact with each other with a difference in peripheral speed to improve toner supply (Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-253203 A [Patent Document 2] JP 2015-41047 A [Patent Document 3] JP 2020-79902 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 2, at the contact position between the developing roller and the toner supply roller, the direction of movement of the surface of the developing roller is the same as the direction of movement of the surface of the toner supply roller, so that the toner that is not developed (residual toner) is likely to be insufficiently scraped off, resulting in a problem that the over-charged residual toner is likely to affect image formation on the second rotation of the developing roller, causing image defects known as ghosts. On the other hand, in the configuration of Patent Document 3, the direction of movement of the surface of the developing roller is opposite to the direction of movement of the surface of the toner supply roller at the contact position between the developing roller and the toner supply roller, so ghosting is unlikely to occur (see claim 4, paragraph

[0099] and FIG. 5 of Patent Document 3). However, there is a problem that toner deterioration such as migration and burial of external additives occurs easily because a large stress is applied to the toner at the contact position between the developing roller and the toner supply roller. The deteriorated toner melts and adheres to the regulating member, causing image defects called development streaks. Therefore, the configuration of Patent Document 3 has an issue in terms of extending the life of the cartridge. In other words, an object of the present disclosure is to provide a process cartridge that is less likely to cause ghosting in faster printers and that does not cause image defects such as development streaks even after long-term use. [Means for solving the problem]

[0005] The present disclosure relates to a process cartridge that is detachably mountable to an image forming apparatus, The process cartridge has a developing chamber, The developing chamber comprises: toner, a developing roller for developing an electrostatic latent image using the toner; a regulating member disposed in contact with the developing roller and regulating a layer thickness of the toner carried on the surface of the developing roller; and a toner supply roller arranged in contact with the developing roller and supplying the toner to the developing roller; having the moving direction of the surface of the developing roller is opposite to the moving direction of the surface of the toner supply roller at a contact position between the surface of the developing roller and the surface of the toner supply roller; The developing roller and the toner supply roller have a peripheral speed ratio R represented by the following formula (E1): 1.1≦R≦2.5 It is configured to satisfy R=V RS / V D (E1) (In formula (E1), V RS represents the absolute value of the peripheral speed of the surface of the toner supply roller [m / sec], and V D represents the absolute value of the peripheral speed of the surface of the developing roller [m / sec].) The toner has toner particles and an external additive A, the toner has an average circularity of 0.955 or more and 0.975 or less, and in the circularity distribution of the toner, a ratio of particles existing in the range of 0.900 or more and 0.930 or less is 2.0% by number or more and 15.0% by number or less, The external additive A is a needle-shaped inorganic fine particle having a major axis of 100 nm or more and 3000 nm or less, and when the toner is observed using a scanning electron microscope, the proportion of toner particles on whose surface the external additive A is confirmed is 30% or more by number. The present invention relates to a process cartridge. Effect of the Invention

[0006] According to the present invention, it is possible to provide a process cartridge which is less likely to cause ghosting in faster printers and which does not cause image defects such as development streaks even after long-term use. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus to which the present disclosure can be applied. [Diagram 2] 1 is a schematic cross-sectional view of a process cartridge according to an embodiment to which the present disclosure can be applied. [Diagram 3] 1 is a schematic cross-sectional view of a developing chamber of a process cartridge according to an embodiment to which the present disclosure can be applied. [Figure 4] 1 is a conceptual cross-sectional view in a lateral direction of a developing blade according to an embodiment to which the present disclosure can be applied; [Diagram 5] 1A to 1C are diagrams illustrating a method of inputting driving force to a toner supply roller according to an embodiment to which the present disclosure can be applied. [Figure 6] 1 is a diagram showing the movement of toner in a developing device according to an embodiment to which the present disclosure can be applied; [Figure 7]1A and 1B are diagrams illustrating the positional relationship between the inner wall of a developing chamber and a supporting end of a developing blade according to an embodiment to which the present disclosure can be applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The process cartridge according to the present disclosure will be described in more detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described in this embodiment are not intended to limit the scope of the present invention to those alone. Furthermore, the materials, shapes, and the like of the members once described in the following description are the same as those described initially unless otherwise specified. Well-known or publicly known technologies in the relevant technical field can be applied to configurations and processes that are not particularly illustrated or described. Furthermore, duplicated descriptions may be omitted.

[0009] The expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified.

[0010] When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

[0011] [Features of the present disclosure] In response to the above-mentioned problems, the inventors investigated a method of suppressing toner deterioration in a cartridge configuration in which the direction of movement of the surface of the developing roller is opposite to the direction of movement of the surface of the toner supply roller, i.e., a cartridge configuration that is excellent in terms of ghosting but is prone to toner deterioration.

[0012] As a result, it was found that, when R represented by formula (E1) is within a certain range, by appropriately controlling the average circularity of the toner, the proportion of particles with relatively low circularity, and the shape of external additive A and its proportion on the toner particle surface, toner deterioration can be suppressed and the above-mentioned problem can be solved.

[0013] That is, the process cartridge of the present disclosure is a process cartridge that is detachably mountable to an image forming apparatus, The process cartridge has a developing chamber, The developing chamber comprises: toner, a developing roller for developing an electrostatic latent image using the toner; a regulating member disposed in contact with the developing roller and regulating a layer thickness of the toner carried on the surface of the developing roller; and a toner supply roller arranged in contact with the developing roller and supplying the toner to the developing roller; having the moving direction of the surface of the developing roller is opposite to the moving direction of the surface of the toner supply roller at a contact position between the surface of the developing roller and the surface of the toner supply roller; The developing roller and the toner supply roller have a peripheral speed ratio R represented by the following formula (E1): 1.1≦R≦2.5 It is configured to satisfy R=V RS / V D (E1) (In formula (E1), V RS represents the absolute value of the peripheral speed of the surface of the toner supply roller [m / sec], and V D represents the absolute value of the peripheral speed of the surface of the developing roller [m / sec].) The toner has toner particles and an external additive A, the toner has an average circularity of 0.955 or more and 0.975 or less, and in the circularity distribution of the toner, a ratio of particles existing in the range of 0.900 or more and 0.930 or less is 2.0% by number or more and 15.0% by number or less, The external additive A is a needle-shaped inorganic fine particle having a major axis of 100 nm or more and 3000 nm or less, and when the toner is observed using a scanning electron microscope, the proportion of toner particles on whose surface the external additive A is confirmed is 30% or more by number. The process cartridge is characterized in that

[0014] The process cartridge of the present disclosure will be described in detail below.

[0015] [Image forming apparatus] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 100 equipped with a process cartridge according to the present disclosure, placed on a horizontal surface in the same manner as when actually used. The image forming apparatus 100 is an in-line full-color laser printer that employs an intermediate transfer method. As shown in FIG. 1, four detachable process cartridges 70 (70Y, 70M, 70C, 70K) are mounted by mounting members (not shown). The upstream side of the process cartridges 70 in the mounting direction of the image forming apparatus 100 is defined as the front side, and the downstream side of the mounting direction is defined as the rear side.

[0016] Each process cartridge 70 includes an electrophotographic photosensitive drum (hereinafter referred to as photosensitive drum) 1 (1a, 1b, 1c, 1d). In each process cartridge 70, a charging roller 2 (2a, 2b, 2c, 2d), a developing roller 25 (25a, 25b, 25c, 25d), a cleaning member 6 (6a, 6b, 6c, 6d), and other process means are integrally arranged around the photosensitive drum 1. The charging roller 2 uniformly charges the surface of the photosensitive drum 1. The developing roller 25 develops the latent image formed on the photosensitive drum 1 with a developer (hereinafter referred to as toner) to make it visible. The cleaning member 6 removes the toner remaining on the photosensitive drum 1 after the toner image formed on the photosensitive drum 1 is transferred to a recording medium. The detailed configurations and positional relationships of the photosensitive drum 1, the charging roller 2, the developing roller 25, and the cleaning member 6 will be described later with reference to FIGS. 2 and 3.

[0017] Further, below the process cartridge 70 in the direction of gravity, a scanner unit 3 is provided for selectively exposing the photosensitive drum 1 based on image information and forming a latent image on the photosensitive drum 1.

[0018] A cassette 17 containing a recording medium S is attached to the lower part of the apparatus main body 100a. A recording medium conveying means is provided so that the recording medium S passes through a secondary transfer roller 69 and a fixing section 74 and is conveyed to the upper part of the apparatus main body 100a. An intermediate transfer unit 5 is provided above the process cartridges 70 (70Y, 70M, 70C, 70K) as an intermediate transfer means for transferring the toner images formed on the photosensitive drums 1 (1a, 1b, 1c, 1d). The intermediate transfer unit 5 has a drive roller 56, a driven roller 57, primary transfer rollers 58 (58a, 58b, 58c, 58d) at positions facing the photosensitive drums 1 of the respective colors, and an opposing roller 59 at a position facing the secondary transfer roller 69, and a transfer belt 50 is stretched over the intermediate transfer unit 5. The transfer belt 50 circulates so as to face and be in contact with all the photosensitive drums 1, and primary transfer is performed from the photosensitive drums 1 onto the transfer belt 50 by applying a voltage to primary transfer rollers 58 (58a, 58b, 58c, 58d). Then, the toner on the transfer belt 50 is transferred to the recording medium S by applying a voltage to an opposing roller 59 and a secondary transfer roller 69 arranged inside the transfer belt 50.

[0019] In forming an image, each photosensitive drum 1 is rotated, and the photosensitive drum 1, which is uniformly charged by the charging roller 2, is selectively exposed to light from the scanner unit 3. As a result, an electrostatic latent image is formed on the photosensitive drum 1. The latent image is developed by the developing roller 25. As a result, a toner image of each color is formed on each photosensitive drum 1. In synchronization with this image formation, the pair of registration rollers 55 conveys the recording medium S to a secondary transfer position where the opposing roller 59 and the secondary transfer roller 69 are in contact with each other with the transfer belt 50 interposed therebetween. Then, a transfer bias voltage is applied to the secondary transfer roller 69, so that the toner image of each color on the transfer belt 50 is secondarily transferred to the recording medium S. As a result, a color image is formed on the recording medium S. The recording medium S on which the color image has been formed is heated and pressed by the fixing unit 74, so that the toner image is fixed. Thereafter, the recording medium S is discharged to the discharge unit 75 by the discharge roller 72. The fixing unit 74 is disposed in the upper part of the device main body 100a.

[0020] [Process Cartridge] Next, a process cartridge 70 embodying the present disclosure will be described with reference to Fig. 2. Fig. 2 is a main cross section of the process cartridge 70 containing toner, in the orientation in which it is attached to the image forming apparatus 100 in Fig. 1. Note that cartridge 70Y containing yellow toner, cartridge 70M containing magenta toner, cartridge 70C containing cyan toner, and cartridge 70K containing black toner have the same configuration.

[0021] The process cartridge 70 includes a cleaning unit 26 and a developing unit 4. The cleaning unit 26 includes a photosensitive drum 1, a charging roller 2, and a cleaning member 6. The developing unit 4 includes a developing roller 25.

[0022] As described above, the charging roller 2 and the cleaning member 6 are disposed on the periphery of the photosensitive drum 1. The cleaning member 6 is composed of an elastic member 7 made of a rubber blade and a cleaning support member 8. The tip of the elastic member 7 made of a rubber blade is disposed in contact with the photosensitive drum 1 in the counter direction to the rotation direction of the photosensitive drum 1. Residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into a removed toner chamber 27.

[0023] The photosensitive drum 1 is rotated in response to an image forming operation by transmitting the driving force of a main body drive motor (not shown) serving as a drive source to the cleaning unit 26. At this time, a drum coupling fixed to the longitudinal end of the photosensitive drum 1 engages with a main body side coupling present on the longitudinal axis of the photosensitive drum 1, so that the driving force is input to the photosensitive drum 1. The charging roller 2 is rotatably attached to the cleaning unit 26 via a charging roller bearing, and is pressed toward the photosensitive drum 1 by a charging roller pressure member, and rotates following the photosensitive drum 1.

[0024] The developing unit 4 is composed of a developing roller 25 that rotates in contact with the photosensitive drum 1, and a developing frame 31 that supports the developing roller 25. The developing frame 31 is composed of a developing chamber 31b and a toner storage chamber 31a (toner storage section), and the toner storage section is disposed vertically below the developing chamber.

[0025] On the circumference of the developing roller 25, there are arranged a toner supply roller 34 which rotates in the direction of the arrow C in contact with the developing roller 25, and a regulating member (developing blade 35) for regulating the toner layer on the developing roller 25. In the embodiment described later, the outer diameter of the developing roller 25 is 12 mm, and the outer diameter of the toner supply roller 34 is 13.2 mm. When the process cartridge 70 is in a posture in which it is mounted in the image forming apparatus 100, an angle α between a straight line A connecting the rotation center 25e of the developing roller 25 and the rotation center 34e of the toner supply roller 34, and a horizontal line H is 9.85 degrees. However, the angle α is not limited to this, and is preferably 9.5 degrees or more and 10.3 degrees or less.

[0026] The developing unit 4 also receives the driving force of a main body drive motor (not shown) separate from the driving source of the cleaning unit, thereby rotating and driving the developing roller 25 and the toner supply roller 34 in response to the image forming operation. The driving force is input via a coupling, as with the cleaning unit 26, and will be described in detail later. The driving force input method using a coupling is preferable from the standpoint of rotational stability compared to driving force input via gears.

[0027] The developing roller 25 is an elastic roller configured by providing a conductive elastic rubber layer having a predetermined volume resistance as an elastic layer around a metal core. The developing roller 25 is composed of a base layer and a surface layer. Silicone rubber is used for the base layer, and urethane rubber is used for the surface layer, with urethane bead particles dispersed in the urethane rubber of the surface layer to set a desired roughness. The developing roller 25 and the photosensitive drum 1 rotate so that their surfaces move in the same direction (from bottom to top in this embodiment) at the opposing portion (contact portion). In this embodiment, toner negatively charged by frictional charging with respect to a predetermined DC bias applied to the developing roller 25 transfers only to the light potential portion due to the potential difference in the developing portion contacting the photosensitive drum 1, thereby visualizing the electrostatic latent image.

[0028] The regulating member (developing blade 35) is disposed below the developing roller 25 and abuts against the developing roller 25 at a counter, and regulates the coating amount of the toner supplied by the toner supply roller 34 and imparts an electric charge. The developing blade 35 is composed of a flexible plate-shaped member and a regulating member support for fixing the plate-shaped member. The plate-shaped member is made of stainless steel (SUS) processed into a leaf spring shape with a thickness of 80 μm, and the abutting portion located at the free end of the plate-shaped member abuts against the developing roller 25 with a required abutting pressure. The toner supplied onto the developing roller 25 is triboelectrically charged by the friction between the developing blade 35 and the developing roller 25, and is charged and at the same time the layer thickness is regulated. In this embodiment, a predetermined voltage is applied to the developing blade 35 from a blade bias power source (not shown) to stabilize the toner coat.

[0029] The charged toner adheres to the surface of the developing roller 25 due to the image force with the developing roller 25. If the adhesion force of this toner to the surface of the developing roller 25 exceeds the regulating force of the developing blade 35, the toner coat on the developing roller 25 becomes disturbed (so-called "regulation failure"). When regulation failure occurs, image defects such as toner adhering to the white background of the image or abnormal density occur.

[0030] Here, the developing blade 35 of this embodiment will be described in detail. As shown in Fig. 3, the developing blade 35 is composed of a supporting metal plate 35a (blade supporting portion) made of stainless steel and a flexible plate-like member 35b (blade portion). The plate-like member is integrated with the supporting metal plate by YAG laser welding.

[0031] 4 is a schematic cross-sectional view in the short side direction of the free end tip portion of the developing blade 35 according to the present disclosure. A surface 811 in FIG.

[0032] 4, in this embodiment, a part of the "tip edge portion 818" on the tip (free end) side of the plate-shaped member 35b that is to come into contact with the developing roller 25 is scraped off by polishing. The part that is scraped off is formed over the entire longitudinal area of ​​the plate-shaped member.

[0033] The developing blade 35 is provided at a free end of the plate-shaped member 35b in the short side direction, and has a contact portion for contacting the surface of the developing roller 25.

[0034] More specifically, before the end of the developing blade 35 is ground, a first surface 811 (first portion) which is a surface that contacts the developing roller 25 in a cross section perpendicular to the longitudinal direction intersects with a third surface 813 (third portion) perpendicular to the first surface 811, forming the above-mentioned "end edge portion 818". Then, by performing the grounding process, the end edge portion 818 is scraped off, and a second surface 812 (second portion) which connects the first surface 811 and the third surface 813 is formed. In the state after the grounding process, the point at the end of the first surface 811 on the free end side is designated as point A, and the point at the end of the second surface 812 on the free end side is designated as point B. Also, a virtual line extending the first surface 811 in the free end direction is designated as L1. Also, a point at which a virtual line L2 which is perpendicular to the virtual line L1 and passes through point B intersects with the virtual line L1 is designated as point C. In this case, the distance between point B and point C is defined as h1, and the distance between point A and point C is defined as d1. In the embodiment described later, h1=15 μm, and d1=40 μm.

[0035] Here, a method for polishing the developing blade 35 used in the present disclosure will be described. The plate-shaped member before being joined to the support member is fixed to the base by being sandwiched between the base and the pressing member.

[0036] The tip of the plate-like member is in contact with the abrasive film wrapped around a rubber roller under a load. In the examples described later, a lapping film sheet with a grain size of #800 is used as the abrasive film, and a load of 500 g (4.9 N) is applied to the rubber roller.

[0037] The polishing film on the rubber roller is arranged in a fixed state, and as the base moves left and right in the longitudinal direction, the tip of the plate-like member is rubbed against the polishing film and finely scraped off.

[0038] The amount of scraping of the plate-like member is proportional to the distance of rubbing with the polishing film, and the longer the rubbing distance, the greater the amount of scraping, and the shorter the distance, the less the amount of scraping. In other words, by controlling the amount of movement of the base, the amount of scraping of the tip edge of the plate-like member can be changed. The above polishing method is one example, and is not limited to this as long as the tip shape of the developing blade can be processed into a desired shape.

[0039] The toner supply roller 34 is in contact with the developing roller 25 at a nip portion N2 (FIG. 6 described later), and is rotated in response to the image forming operation by receiving the driving force of a driving motor (not shown). This will be described in detail with reference to FIG.

[0040] The driving force from the main body drive motor is transmitted to a coupling 201 (driving force receiving portion) provided at the shaft end of the toner supply roller 34, and the driving force is transmitted to the toner supply roller 34 via an intermediate body 202 and a driving force transmission member 203 (the intermediate body 202 and the driving force transmission member 203 are a first driving force transmission portion). The driving force of the toner supply roller 34 is transmitted to the developing roller 25 by gears (204a to 204c) provided between the toner supply roller 34 and the developing roller 25, and the developing roller 25 rotates (the gear 204c is a second driving force transmission portion, and the gear 204a is a third driving force transmission portion). In detail, the driving force is transmitted to the idler gear 204b by the rotation of the gear 204c fixed to the toner supply roller 34, and the idler gear 204b rotates. The driving force is transmitted to the gear 204a fixed to the developing roller 25 by the rotation of the idler gear 204b, and the developing roller 25 rotates together with the gear 204a.

[0041] 1 and 2, the driving force from the apparatus main body 100a to the developing unit 4 is input from the longitudinal axis of the toner supply roller 34, but if the driving force from the apparatus main body 100a to the developing unit 4 were input from the longitudinal axis of the developing roller 25, the driving input positions to the cleaning unit 26 and the developing unit 4 would be close to each other due to the relationship of developing by contacting the photosensitive drum 1 and the developing roller 25. With such an input portion arrangement, it is difficult to simply configure the driving input portion of the apparatus main body 100a, and is not preferable when configuring a more stable driving input portion at low cost.

[0042] In contrast, in this embodiment, the driving force to the developing unit 4 is input from the longitudinal axis of the toner supply roller 34, so that the distance between the driving force input position to the cleaning unit 26 and the driving force input position to the developing unit 4 can be increased, which is more preferable when configuring the driving force input portion of the device main body 100a.

[0043] On the other hand, in the configuration of this embodiment in which the driving force from the apparatus main body 100a is transmitted to the developing roller 25 via the toner supply roller 34, multiple gears must be passed through in order to drive the developing roller 25, and therefore the rotation stability of the developing roller 25 is inferior to that of the configuration in which the driving force is transmitted to the developing roller 25. As a result, the regulating force of the developing blade 35 may become unstable, and this configuration is disadvantageous in terms of regulating failure.

[0044] In addition, the toner supply roller 34 and the developing roller 25 rotate with a difference in peripheral speed at their contact position (nip portion N2). This operation recovers the remaining toner on the developing roller 25 while supplying toner to the developing roller 25.

[0045] In the configuration of the present disclosure, the moving direction of the surface of the developing roller is opposite to the moving direction of the surface of the toner supply roller at the nip portion N2 of the toner supply roller, The peripheral speed of the toner supply roller 34 in the nip portion N2 is V RS , the peripheral speed of the developing roller 25 is V D Then, the rotation occurs so that R in the following formula (E1) satisfies 1.1≦R≦2.5. R=V RS / V D (E1)

[0046] In other words, if the radius of the toner supply roller 34 is rRS, the rotational angular velocity is ωRS, the radius of the development roller 25 is rD, and the rotational angular velocity is ωD, then the relationship between the toner supply roller 34 and the development roller 25 is expressed by the following formula (E2): λ=ωRS / ωD (E2) (In formula (E2), ωRS represents the rotational angular velocity [rad / sec] of the toner supply roller, and ωD represents the rotational angular velocity [rad / sec] of the developing roller.) This means that the rotational angular velocity ratio λ expressed by is 1.1≦λ×rRS / rD≦2.5, and in the embodiment described later, the radius of the toner supply roller is 3.3 mm and the radius of the developing roller is 3.0 mm, so that λ≈1.14.

[0047] When the toner supply roller and the developing roller rotate in the same direction at the contact portion, the remaining toner on the developing roller is not sufficiently collected, and the image defect called ghost due to the overcharging of the remaining toner is likely to occur. Similarly, when R is smaller than 1.1, the remaining toner on the developing roller is not sufficiently collected, and the image defect called ghost due to the overcharging of the remaining toner occurs. On the other hand, when R is larger than 2.5, the stress applied to the toner at the nip portion N2 is large, and the development streaks due to toner deterioration and member fusion occur.

[0048] A more preferable range for R is 1.2≦R≦1.5.

[0049] Further, the toner supply roller 34 and the developing roller 25 are in contact with each other with a predetermined intrusion amount, that is, the indentation amount ΔE by which the toner supply roller 34 is made in a concave shape by the developing roller 25 .

[0050] The toner supply roller 34 comprises a conductive support and a foam layer supported by the conductive support. Specifically, the conductive support is a core metal electrode having an outer diameter of φ5 (mm), and a foamed urethane layer is provided around the core metal electrode as a foamed layer made of open cells (open cells) in which air bubbles are connected to each other, and the roller rotates in the direction of C in the figure. By making the urethane surface layer open cells in this way, a large amount of toner can enter the inside of the toner supply roller 34. The resistance of the toner supply roller 34 in the embodiment described later is 1×10 9 (Ω).

[0051] In the embodiment described later, the amount of penetration of the toner supply roller 34 into the developing roller 25, that is, the amount of depression ΔE by which the toner supply roller 34 is made concave by the developing roller 25, is set to 1.0 mm.

[0052] Here, a method for measuring the resistance of the toner supply roller 34 will be described. The toner supply roller 34 is brought into contact with an aluminum sleeve having a diameter of 30 mm so that the intrusion amount, which will be described later, is 1.5 mm. By rotating this aluminum sleeve, the toner supply roller 34 is rotated at 30 rpm relative to the aluminum sleeve.

[0053] Next, a DC voltage of -50V is applied to the developing roller 25. At this time, a resistor of 10 kΩ is provided on the earth side, and the current is calculated by measuring the voltage across the resistor, and the resistance of the toner supply roller 34 is calculated. In this embodiment, the surface cell diameter of the toner supply roller 34 is set to 50 μm to 1000 μm.

[0054] Here, the cell diameter refers to the average diameter of foam cells in an arbitrary cross section, and the area of ​​the largest foam cell is measured from an enlarged image of the arbitrary cross section, and the maximum cell diameter is obtained by converting this area into a diameter equivalent to a perfect circle. After removing foam cells that are 1 / 2 or less of this maximum cell diameter as noise, the remaining individual cell areas are similarly converted to obtain the average cell diameter.

[0055] The toner supplied from the toner supply roller 34 to the surface of the developing roller 25 is frictionally charged by the rubbing between the regulating member (developing blade 35) and the developing roller 25, and the layer thickness is regulated at the same time as the charge is imparted. The toner is then transported to the contact portion (developing portion) between the photosensitive drum 1 and the developing roller 25, and transferred to the light potential portion. Residual toner remaining on the surface of the developing roller 25 returns to the developer container, is collected from the surface of the developing roller 25 by the toner supply roller 34, and is stored inside the toner supply roller 34.

[0056] Here, the flow of toner inside the developing chamber 31b will be described with reference to Fig. 6. Fig. 6 is an enlarged schematic cross-sectional view of the inside of the developing chamber 31b, and shows the movement of toner transported to the toner supply roller 34 by the toner transport member 36 shown in Fig. 2.

[0057] A portion of the toner G transported to the upper portion of the toner supply roller 34 by the toner transport member 36 is sucked into the inside of the toner supply roller 34 due to the restoration of the toner supply roller 34 on the downstream side of the rotation of the toner supply roller 34 at the nip portion N2 (F1), and is stored inside the toner supply roller 34 together with the remaining toner recovered from the surface of the developing roller 25 and stored inside the toner supply roller 34. Then, due to the rotation of the toner supply roller 34 in the C direction, the toner G is transported to the downstream side of the rotation direction of the toner supply roller 34 at the nip portion N2. Due to the deformation of the toner supply roller 34 caused by the toner supply roller 34 coming into contact with the developing roller 25 on the downstream side of the rotation direction of the toner supply roller 34, the toner stored inside is expelled (F2).

[0058] The toner discharged from the toner supply roller 34 that does not reach the surface of the developing roller 25 is gradually transported by the propulsion force toward the developing opening (opening) due to the ejection force from the toner supply roller 34, and passes through the developing opening and is returned to the toner storage chamber 31a (F3).

[0059] In this way, the toner circulates smoothly between the developing chamber 31b and the toner storage chamber 31a, thereby suppressing toner deterioration, and even when images with low print coverage are output continuously, the occurrence of toner aggregation is suppressed, making it possible to stably output high-quality images.

[0060] Here, if the flow (F3) of toner returning to the toner storage chamber 31a becomes insufficient, the toner is pressed down and aggregates in the area below the toner supply roller 34 and the developing roller 25. Then, the toner enters the nip portion N2 between the toner supply roller 34 and the developing roller 25, and the contact of the toner supply roller 34 with the developing roller 25 becomes insufficient. An area occurs where the remaining toner on the developing roller 25 cannot be sufficiently collected by the toner supply roller 34, and a specific toner is carried around by the developing roller 25 and passes through the contact portion between the regulating member (developing blade 35) and the developing roller 25 more than necessary, resulting in the generation of toner that is excessively charged. As a result, the adhesion force of the toner exceeds the regulating force of the regulating member (developing blade 35), and a regulating failure may occur.

[0061] This phenomenon is likely to occur, for example, when images with a low printing rate are continuously output in a low-temperature, low-humidity environment. This is because the residual toner collected from the developing roller 25 by the toner supply roller 34 accumulates in the developing chamber 31b. The residual toner collected from the developing roller 25 is charged, so the toner particles tend to electrostatically clump together. This reduces the fluidity of the toner in the developing chamber 31b, making the flow of toner (F3) returning to the toner storage chamber 31a insufficient, and creating a state in which toner clumping is likely to occur in the areas below the toner supply roller 34 and the developing roller 25.

[0062] In response to this, there is a method of arranging a toner stirring member below the toner supply roller 34 in the developing chamber 31b, thereby creating a toner flow (F3) that returns to the toner storage chamber 31a. However, when a toner stirring member is provided in the developing chamber 31b, the toner deteriorates due to friction between the toner and the toner stirring member in the developing chamber 31b, and toner melting onto the developing roller 25 is observed when images with a low printing rate are continuously printed. In addition, since it is necessary to provide a toner stirring member as an additional member in addition to the toner supply roller 34 in the developing chamber 31b, the device configuration becomes complicated. Therefore, in this embodiment, no members that are driven by motor drive are provided in the developing chamber 31b other than the developing roller 25 and the toner supply roller 34.

[0063] In addition, in a configuration in which only the developing roller 25 and the toner supply roller 34 are arranged in the developing chamber 31b, in order to efficiently use the toner in the developing chamber 31b, the inner wall of the developing chamber 31b is set as follows relative to the toner supply roller 34. This will be specifically explained with reference to FIG.

[0064] In FIG. 7, R1 and R2 indicate tangents (vertical lines) to the outer peripheral surface of the toner supply roller 34 that extends in the vertical direction. Also, horizontal line H2 indicates a horizontal line that passes through the support end of the regulating member (developing blade 35). In the region between R1 and R2 of the inner wall of the developing chamber 31b, at least a part of it is located vertically above the horizontal line H2 (region 138 in the figure). This makes it possible to further reduce the toner remaining in the developing chamber 31b that is not used for printing, and toner in the developing chamber 31b can be used efficiently.

[0065] As shown in FIG. 2, a blowout prevention sheet 20 is disposed as a developer contact sheet for preventing toner from leaking from the developing frame 31 in contact with the developing roller 25.

[0066] Further, the toner storage chamber 31a of the developing frame 31 is provided with a toner transport member 36 for stirring the stored toner and transporting the toner to the toner supply roller 34. As shown in Fig. 2, the toner transport member 36 is composed of a stirring shaft 36a that can be rotated by a driving force from the apparatus main body 100a, and a sheet member 36b that is attached to the stirring shaft 36a and rotates together with the stirring shaft 36a, and the sheet member 36b has elasticity.

[0067] Next, the toner transport of the developing unit will be described. In the toner storage chamber 31a, the sheet member 36b of the toner transport member is provided so that the free end of the toner transport member contacts the wall surface of the toner storage section in an area A upstream of the opening 31c (communication port) in the rotation direction of the toner transport member. In addition, the sheet member 36b deforms against elasticity as the toner transport member rotates so that the free end side is located upstream of the rotation direction of the toner transport member rather than the rotation shaft side.

[0068] That is, as the sheet member 36b rotates, it comes into contact with the deformed portion 31a1 on the inner surface of the toner storage chamber. This causes the sheet member 36b to receive force from the deformed portion 31a1. As a result, the sheet member 36b deforms against the elastic force of the sheet member 36b. Furthermore, as the sheet member 36b rotates in contact with the deformed portion 31a1, the toner is carried on the surface downstream in the rotation direction and conveyed. In this embodiment, the deformed portion 31a1 refers to the portion of the inner wall of the toner storage chamber up to the point where the sheet member 36b leaves the wall, as shown in FIG. 2 (also referred to as region A).

[0069] Furthermore, at a predetermined position (also referred to as position B) in the restoring portion 31a2 downstream of the region A in the rotation direction of the toner transport member and upstream of the opening in the rotation direction of the toner transport member, the free end of the toner transport member is released from contact with the wall surface of the toner storage portion. At that time, the deformed toner transport member is restored by elasticity, and the transported toner flies toward the communication opening. In the embodiment described later, the restoring portion 31a2 is disposed above a horizontal plane including the rotation axis of the transport member.

[0070] Therefore, after the tip of the free end side of the sheet member 36b passes through the deformation portion 31a1 as the sheet member 36b rotates, the contact with the inner wall of the sheet member 36b is released at the restoration portion 31a2. Then, the sheet member 36b is released from the state in which it was deformed by the deformation portion 31a1 and is restored to its natural state (original shape) by its own elastic restoring force. Due to the shape change of the sheet member 36b in the restoration direction, the toner carried and transported on the sheet member 36b flies against gravity toward the opening 31c. This opening 31c is located downstream of the restoration portion 31a2 in the rotation direction of the sheet member 36b. A part of the toner that flies toward the opening 31c is transported into the developing chamber 31b. On the other hand, the toner that does not reach the developing chamber 31b falls into the toner storage chamber 31a and remains at the bottom of the toner storage chamber 31a, and returns to its original state. By repeating this cycle, the toner is stirred and transported.

[0071] In addition, the boundary between the deformation portion 31a1 and the restoration portion 31a2 is located below the lower end of the opening 31c (communication port), and when viewed from the axial direction of the developing roller 25, the center of rotation of the toner transport member 36 and the center of rotation of the developing roller 25 are on the same side of a vertical line passing through the boundary, and the maximum value of the radius of rotation of the toner transport member 36 is greater than the distance between the center of rotation of the transport member and the lower end of the communication port.

[0072] The configuration having the deformation portion 31a1 and the restoration portion 31a2 as described above is advantageous for increasing the efficiency of transporting toner to the developing chamber 31b, but is prone to obstructing the flow of toner (F3) returning to the toner storage chamber, making it prone to regulation failure.

[0073] In this embodiment, the length of the sheet member 36b in the direction of the rotation radius of the rotation axis in the natural state is set to be longer than the distance from the rotation axis to the lower end of the developing opening in the same direction. This configuration is advantageous for increasing the efficiency of transporting toner to the developing chamber 31b, but it is likely to obstruct the flow (F3) of toner returning to the toner storage chamber 31a, and therefore is likely to cause regulation failure.

[0074] In order to transport a sufficient amount of toner from the toner storage chamber 31a to the developing chamber 31b, two sets of sheet members 36b are attached at different positions on the stirring shaft 36a. This configuration is advantageous for increasing the efficiency of transporting toner to the developing chamber 31b, but it is likely to obstruct the flow (F3) of toner returning to the toner storage chamber 31a, making it prone to regulation failure.

[0075] 〔toner〕 The toner of the present disclosure will be described in further detail below.

[0076] The toner of the present disclosure includes toner particles and an external additive A, the toner has an average circularity of 0.955 or more and 0.975 or less, and in a circularity distribution of the toner, a ratio of particles existing in a range of 0.900 or more and 0.930 or less is 2.0% by number or more and 15.0% by number or less, The external additive A is a needle-shaped inorganic fine particle having a major axis of 100 nm or more and 3000 nm or less, and when the toner is observed using a scanning electron microscope, the ratio of toner particles on whose surface the external additive A is confirmed to be present is 30% by number or more. This is a toner.

[0077] The authors consider the mechanism by which the toner having the above-described configuration used in the process cartridge of the present disclosure exerts the effects of the present disclosure to be as follows.

[0078] The external additive A of the present disclosure is inorganic fine particles having a needle-like shape. The needle-like inorganic fine particles present on the toner surface act as spacers when the toner passes through the contact area between the toner supply roller and the developing roller or the contact area between the developing roller and the regulating member, making it possible to suppress development streaks caused by toner deterioration.

[0079] In addition, the circularity of the toner is also an important item related to toner deterioration. The closer the toner is to a sphere, that is, the higher the circularity of the toner, the more the contact area between each component and the toner can be minimized, which is preferable from the viewpoint of toner deterioration. However, in a cartridge configuration that enables high-speed printing, the higher the circularity of the toner, the more the aforementioned acicular inorganic fine particles tend to roll on the surface of the toner particles, making it difficult to achieve the spacer effect. In the present disclosure, a toner having a high overall average circularity is mixed with a toner having a low average circularity in part. In a toner having a low average circularity, the acicular inorganic fine particles are less likely to roll on the toner surface, and the spacer effect of the acicular inorganic fine particles is more likely to be achieved. Even if rolling does occur, the spacer effect of the acicular inorganic fine particles is more likely to be maintained than in a spherical toner, and the spacer effect can be maximized. The authors believe that the effects of the present disclosure are achieved by the above-mentioned mechanism.

[0080] The toner of the present disclosure has an average circularity of 0.955 or more and 0.975 or less. If the average circularity is less than 0.955, even if there is a spacer effect due to the needle-shaped inorganic fine particles, the contact area between the toner and each member is too large, so that toner deterioration and development streaks due to member fusion occur. On the other hand, if the average circularity is more than 0.975, it is difficult to control the ratio of particles with a circularity of 0.900 or more and 0.930 or less to a desired range, as described below.

[0081] In the toner of the present disclosure, the ratio of particles present in the range of 0.900 to 0.930 in the circularity distribution of the toner described above is 2.0% by number to 15.0% by number. It is believed that a toner having a circularity of 0.900 to 0.930 and having needle-shaped inorganic fine particles on the toner surface is a toner that can maximize the spacer effect.

[0082] Hereinafter, toner with a circularity between 0.900 and 0.930 will be referred to as "irregular toner." When the irregular toner content is less than 2.0% by number, the spacer effect is insufficient, causing toner deterioration and development streaks due to component fusion. On the other hand, when the irregular toner content is more than 15.0% by number, the effect of irregular toner that does not have acicular inorganic fine particles on the toner surface cannot be ignored. Irregular toner that does not have acicular inorganic fine particles on the toner surface has a large contact area with each component, and the spacer effect of the acicular inorganic fine particles cannot be expected, causing toner deterioration and development streaks due to component fusion.

[0083] In order to obtain the above toner shape, it is preferable to manufacture the toner by a chemical toner manufacturing method in which toner particles are obtained in an aqueous medium, such as an emulsion aggregation method or a suspension polymerization method, etc. Specifically, the above toner shape can be obtained by going through a spheronization step, a cooling step, and an annealing step in the manufacturing process.

[0084] An example of the spheronization step is a heat treatment step in which heat treatment is carried out at 90° C. or higher, preferably 92° C. or higher, and preferably 95° C. or lower.

[0085] An example of the cooling step is a step in which the cooling treatment is carried out at a cooling rate of 0.1° C. / sec or more, preferably 0.5° C. / sec or more, more preferably 2° C. / sec or more, and even more preferably 4° C. / sec or more.

[0086] An example of the annealing step is a heat treatment step in which heat treatment is performed for 5 hours or less at a temperature at which the glass transition temperature (Tg) of the toner is maximized.

[0087] By performing these steps under appropriate conditions, it becomes easier to achieve the toner shape of the present disclosure.

[0088] The toner of the present disclosure further contains an external additive A. The external additive A of the present disclosure is acicular inorganic fine particles having a major axis of 100 nm or more and 3000 nm or less.

[0089] If the major axis of the external additive A is smaller than 100 nm, the external additive A rolls in all directions on the toner surface, and the spacer effect is not sufficiently obtained, resulting in development streaks due to toner deterioration and member fusion. If the major axis is larger than 3000 nm, the external additive A is more likely to be detached from the toner surface, and the spacer effect is not sufficiently obtained, resulting in development streaks due to toner deterioration and member fusion. For the same reasons, the major axis is preferably 500 nm or more and 2000 nm or less, and more preferably 800 nm or more and 1700 nm or less.

[0090] In the embodiments of the present specification, the term "acicular" may refer to particles that are irregular, elongated, or have a needle shape, a rice shape, a stick shape, a butterfly shape, or a bowtie shape. The external additive A being acicular not only makes it difficult for the external additive A to roll on the toner surface, but also limits the direction of the rolling to the minor axis direction, so that the spacer effect is more easily exhibited.

[0091] From the viewpoint of further improving the above-mentioned spacer effect, the external additive A preferably has an aspect ratio of 5.0 or more. More preferably, it is 6.0 or more, and even more preferably, it is 8.0 or more. Although there is no particular upper limit, from the viewpoint of facilitating the production of a suitable particle size, it is preferably 20.0 or less, and even more preferably 16.0 or less.

[0092] When the toner of the present disclosure is observed using a scanning electron microscope, the ratio of toner particles on which it is confirmed that the external additive A is present on the surface is 30% by number or more. If the ratio of toner particles on which it is confirmed that the external additive A is present on the surface is less than 30% by number, the ratio of particles on which the spacer effect of the external additive A is not obtained becomes too high, and the effect of the present disclosure cannot be obtained sufficiently. For the same reason, it is preferably 40% by number or more, and more preferably 50% by number or more.

[0093] The ratio of toner particles on whose surface the external additive A is confirmed can be controlled by appropriately adjusting the conditions for external addition.

[0094] External additive A has a resistivity of 1.0×10 5 Ω cm or more 1.0×10 8 It is preferable that the resistivity is Ω·cm or less. When the resistivity is in this range, the balance between the charge of the toner and the charge leakage is excellent, and the initial charge rise immediately after starting up the main body is improved. For the same reason, it is more preferable that the resistivity is 1.0×10 6 Ω cm or more 5.0×10 7 Ω·cm or less.

[0095] The external additive A only needs to satisfy the above-mentioned range of physical properties, and specific examples thereof include titanium oxide particles and aluminum oxide particles. Among them, it is preferable that the external additive A contains titanium oxide particles. When the external additive A contains titanium oxide particles, it becomes easier to set the above-mentioned resistivity within a desired range. It is more preferable that the external additive A contains rutile-type titanium oxide particles.

[0096] The toner of the present disclosure preferably has an abundance of boron atoms in the toner particles of 0.1 ppm by mass or more and 100.0 ppm by mass or less. By incorporating boron atoms in the toner particles, appropriate charge transfer occurs between or within the toner particles, and the charge retention performance of the toner can be stabilized from the beginning to the end of use.

[0097] The means for incorporating boron atoms into toner particles is not particularly limited. For example, boric acid can be incorporated into toner particles by adding it internally to the toner particles or using it as an aggregating agent in the aggregation method. Adding boric acid as an aggregating agent makes it easier to introduce boron atoms near the surface of the toner particles. At the stage of using it as a raw material, it may be used in the form of organic boric acid, boric acid salt, boric acid ester, etc. When the toner particles are produced in an aqueous medium, it is preferable to add it as a boric acid salt from the viewpoint of reactivity and production stability. Specifically, for example, sodium tetraborate, ammonium borate, etc. can be mentioned, and in particular, borax is preferably used.

[0098] Borax is sodium tetraborate 2 B 4 O 7This is expressed as a decahydrate, and changes to boric acid in an acidic aqueous solution. Therefore, when used in an aqueous medium under an acidic environment, borax is preferably used.

[0099] [Toner components] Each component constituting the toner and the method for producing the toner will be described in more detail.

[0100] <Binding resin> The toner particles contain a binder resin, and the content of the binder resin is preferably 50% by mass or more based on the total amount of the resin components in the toner particles.

[0101] The binder resin is not particularly limited, and examples thereof include styrene-acrylic resin, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, mixed resins or composite resins thereof, etc. Styrene-acrylic resin and polyester resin are preferred because they are inexpensive, easily available, and have excellent low-temperature fixing properties.

[0102] (polyester resin) The polyester resin can be obtained by combining suitable compounds selected from polyvalent carboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using a conventionally known method such as an ester exchange method or a polycondensation method.

[0103] Polycarboxylic acids are compounds containing two or more carboxy groups in one molecule. Among them, dicarboxylic acids are compounds containing two carboxy groups in one molecule and are preferably used.

[0104] Examples of dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimelic acid, suberic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediacetic acid, o-phenylenediacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, and cyclohexanedicarboxylic acid.

[0105] Examples of polyvalent carboxylic acids other than dicarboxylic acids include trimellitic acid, trimesic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, pyrene tetracarboxylic acid, itaconic acid, glutaconic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, etc. These may be used alone or in combination of two or more.

[0106] A polyol is a compound containing two or more hydroxyl groups in one molecule. Among them, a diol is a compound containing two hydroxyl groups in one molecule, and is preferably used.

[0107] Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 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, 1,14-eicosandecanediol, diethylene glycol, Examples of the bisphenols include triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butenediol, neopentyl glycol, 1,4-cyclohexanediol, polytetramethylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above bisphenols.

[0108] Among these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and their combined use with alkylene glycols having 2 to 12 carbon atoms.

[0109] Examples of trivalent or higher polyols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, trisphenol PA, phenol novolac, cresol novolac, alkylene oxide adducts of the above trivalent or higher polyphenols, etc. These may be used alone or in combination of two or more.

[0110] (styrene acrylic resin) Examples of the styrene-acrylic resin include homopolymers made of the following polymerizable monomers, copolymers obtained by combining two or more of these, and mixtures thereof.

[0111] Styrenic monomers such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene and p-phenylstyrene; (Meth)acrylic monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate and 2-benzoyloxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, maleic acid; Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; Polyolefins such as ethylene, propylene, and butadiene.

[0112] The styrene acrylic resin may use a polyfunctional polymerizable monomer as required. Examples of the polyfunctional polymerizable monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0113] In order to control the degree of polymerization, it is also possible to further add a known chain transfer agent and polymerization inhibitor.

[0114] Examples of the polymerization initiator for obtaining the styrene-acrylic resin include organic peroxide-based initiators and azo-based polymerization initiators.

[0115] Examples of the organic peroxide initiator include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butylperoxypivalate.

[0116] Examples of the azo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0117] Furthermore, a redox initiator, which is a combination of an oxidizing substance and a reducing substance, can also be used as the polymerization initiator.

[0118] Oxidizing substances include inorganic peroxides such as hydrogen peroxide, persulfates (sodium, potassium and ammonium salts) and oxidizing metal salts such as tetravalent cerium salts.

[0119] Examples of reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (amines having from 1 to 6 carbon atoms, such as methylamine and ethylamine), amino compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium hydrosulfite, sodium hydrogensulfite, sodium sulfite, and sodium formaldehyde sulfoxylate, lower alcohols (having from 1 to 6 carbon atoms), ascorbic acid or a salt thereof, and lower aldehydes (having from 1 to 6 carbon atoms).

[0120] The polymerization initiator is selected with reference to its 10-hour half-life temperature and is used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 20.0 parts by mass per 100.0 parts by mass of polymerizable monomer.

[0121] <Release agent> The toner may contain a known wax as a releasing agent.

[0122] Specific examples include petroleum waxes and derivatives thereof, such as paraffin wax, microcrystalline wax, and petroleum waxes represented by petrolactam, montan wax and derivatives thereof, hydrocarbon waxes produced by the Fischer-Tropsch process and derivatives thereof, polyolefin waxes and derivatives thereof, such as polyethylene, natural waxes and derivatives thereof, such as carnauba wax and candelilla wax, and derivatives thereof. Derivatives also include oxides, block copolymers with vinyl monomers, and graft modified products.

[0123] Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid or their acid amides, esters and ketones, hydrogenated castor oil and its derivatives, vegetable waxes and animal waxes. These can be used alone or in combination.

[0124] Among these, polyolefin, Fischer-Tropsch hydrocarbon wax, or petroleum wax is preferably used since it tends to improve the developing property and transfer property. Note that these waxes may contain an antioxidant within a range that does not affect the properties of the toner.

[0125] From the viewpoint of phase separation with respect to the binder resin or crystallization temperature, preferred examples include higher fatty acid esters such as behenyl behenate and dibehenyl sebacate.

[0126] The content of the release agent is preferably 1.0 part by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0127] The melting point of the release agent is preferably from 30° C. to 120° C., more preferably from 60° C. to 100° C. By using a release agent having a melting point of from 30° C. to 120° C., the release effect is efficiently exerted and a wider fixing area is secured.

[0128] <Plasticizer> In the toner of the present disclosure, it is preferable to use a crystalline plasticizer in order to improve sharp melting properties. The plasticizer is not particularly limited, and any of the known plasticizers used in toners such as those described below can be used.

[0129] Esters of monohydric alcohols and fatty carboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate, or esters of monohydric carboxylic acids and fatty alcohols; esters of dihydric alcohols and fatty carboxylic acids, such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate, or esters of dihydric carboxylic acids and fatty alcohols; esters of trihydric alcohols and fatty carboxylic acids, such as glycerol tribehenate, or esters of trihydric carboxylic acids and fatty alcohols; pentaerythritol tetrastearate esters of tetrahydric alcohols and aliphatic carboxylic acids, such as pentaerythritol tetrapalmitate, or esters of tetrahydric carboxylic acids and aliphatic alcohols; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate, dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerin behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; and natural ester waxes, such as carnauba wax and rice wax. These may be used alone or in combination.

[0130] <Coloring agent> The toner particles may contain a colorant. As the colorant, known pigments and dyes can be used. From the viewpoint of excellent weather resistance, the colorant is preferably a pigment.

[0131] Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specific examples include the following: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0132] Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254, and CI Pigment Violet 19.

[0133] Yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specific examples include the following: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, and 194.

[0134] Examples of black colorants include those toned to black using the above yellow, magenta and cyan colorants, as well as carbon black.

[0135] These colorants can be used alone or in mixtures, or further in the form of a solid solution.

[0136] The colorant is preferably used in an amount of 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0137] <Charge control agents and charge control resins> The toner particles may contain a charge control agent or resin.

[0138] As the charge control agent, a known one can be used, and a charge control agent that has a high triboelectric charging speed and can stably maintain a constant triboelectric charge amount is particularly preferred. Furthermore, when the toner particles are produced by a suspension polymerization method, a charge control agent that has low polymerization inhibition properties and is substantially free of solubilized matter in an aqueous medium is particularly preferred.

[0139] Examples of toners that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge control resins.

[0140] The charge control resin may be a polymer or copolymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group. As the polymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group, a polymer containing a sulfonic acid group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in a copolymerization ratio of 2% by mass or more is preferable, and a polymer containing a sulfonic acid group-containing methacrylamide monomer in a copolymerization ratio of 5% by mass or more is more preferable.

[0141] The charge control resin preferably has a glass transition temperature (Tg) of 35° C. or more and 90° C. or less, a peak molecular weight (Mp) of 10,000 or more and 30,000 or less, and a weight average molecular weight (Mw) of 25,000 or more and 50,000 or less. When used, it is possible to impart preferable triboelectric charging characteristics without affecting the thermal characteristics required for the toner particles. Furthermore, when the charge control resin contains a sulfonic acid group, for example, the dispersibility of the charge control resin itself in the polymerizable monomer composition and the dispersibility of the colorant are improved, and the coloring power, transparency, and triboelectric charging characteristics can be further improved.

[0142] These charge control agents or charge control resins may be added alone or in combination of two or more kinds.

[0143] The amount of the charge control agent or charge control resin added is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, relative to 100.0 parts by mass of the binder resin.

[0144] [Toner manufacturing method] The method for producing the toner is not particularly limited, and known methods such as a pulverization method, a suspension polymerization method, a dissolution suspension method, an emulsion aggregation method, and a dispersion polymerization method can be used. Here, the toner is preferably produced by the method shown below. That is, the toner is preferably produced by an emulsion aggregation method.

[0145] The toner manufacturing method includes the following steps (1) to (3): (1) a dispersion step of preparing a binder resin microparticle dispersion liquid containing the binder resin; (2) an aggregating step of aggregating the binder resin fine particles contained in the binder resin fine particle dispersion to form aggregates; and (3) a fusion step of heating the aggregates to fuse them together in that order, In the method for producing a toner, a boric acid source is added in at least one of the aggregation step and the coalescence step.

[0146] In addition, during or after the fusion step, the following steps (4) to (6) are carried out: (4) a spheronization step of further heating the agglomerates at an elevated temperature; (5) a cooling step of cooling the aggregate at a cooling rate of 0.1° C. / sec or more; and (6) an annealing step of heating and holding the aggregate at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin; It is preferable to have them in this order.

[0147] The toner is preferably produced by an emulsion aggregation method, since the toner shape can be controlled. Details of the emulsion aggregation method will be described below.

[0148] <Emulsification aggregation method> The emulsion aggregation method is a method in which an aqueous dispersion of fine particles made of the constituent materials of toner particles, which are sufficiently small relative to the target particle size, is prepared in advance, and the fine particles are aggregated in an aqueous medium until they reach the particle size of the toner particles, and the resin is fused by heating or the like to produce toner particles.

[0149] That is, in the emulsion aggregation method, toner particles are manufactured through a dispersion process in which a fine particle dispersion liquid made of the constituent materials of the toner particles is prepared, an aggregation process in which fine particles made of the constituent materials of the toner particles are aggregated and the particle size is controlled until it reaches the particle size of the toner particles, a fusion process in which the resin contained in the obtained aggregated particles is fused, a further melting process by heating or the like to control the surface shape of the toner, a subsequent cooling process, a metal removal process in which the obtained toner is filtered and excess polyvalent metal ions are removed, a filtration / washing process in which the toner particles are washed with ion-exchanged water or the like, and a process in which moisture is removed from the washed toner particles and they are dried.

[0150] "Process for preparing a resin fine particle dispersion (dispersion process)" The resin microparticle dispersion liquid can be prepared by a known method, but is not limited to these methods.The known methods include, for example, emulsion polymerization method, self-emulsification method, phase inversion emulsification method in which resin is emulsified by adding aqueous medium to the resin solution dissolved in organic solvent, and forced emulsification method in which resin is forcedly emulsified by high temperature treatment in aqueous medium without using organic solvent.

[0151] Specifically, the binder resin is dissolved in an organic solvent capable of dissolving it, and a surfactant or a basic compound is added. In this case, if the binder resin is a crystalline resin having a melting point, it may be dissolved by heating it to above its melting point. Then, while stirring with a homogenizer or the like, an aqueous medium is slowly added to precipitate the resin fine particles. Thereafter, the solvent is removed by heating or reducing pressure to prepare an aqueous dispersion of the resin fine particles. Any organic solvent can be used to dissolve the resin as long as it can dissolve the resin, but it is preferable to use an organic solvent that forms a homogeneous phase with water, such as toluene, from the viewpoint of suppressing the generation of coarse powder.

[0152] The surfactant used during the emulsification is not particularly limited, but examples thereof include anionic surfactants such as sulfate salts, sulfonates, carboxylates, phosphates, 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. The surfactants may be used alone or in combination of two or more.

[0153] Examples of the basic compound used in the dispersion step include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as ammonia, triethylamine, trimethylamine, dimethylaminoethanol, and diethylaminoethanol. The basic compound may be used alone or in combination of two or more.

[0154] The 50% particle size (D50) based on volume distribution of the binder resin particles in the aqueous dispersion of the resin particles is preferably 0.05 μm to 1.0 μm, and more preferably 0.05 μm to 0.4 μm. By adjusting the 50% particle size (D50) based on volume distribution to the above range, it becomes easy to obtain toner particles with a volume average particle size of 3 μm to 10 μm, which is appropriate for toner particles.

[0155] The 50% particle size (D50) based on volume distribution is measured using a dynamic light scattering particle size distribution analyzer Nanotrac UPA-EX150 (manufactured by Nikkiso).

[0156] (Colorant particle dispersion) A colorant particle dispersion may be used as necessary. The colorant particle dispersion may be prepared by the following known methods, but is not limited to these methods. The colorant, the aqueous medium, and the dispersant may be mixed by a known mixer such as a stirrer, an emulsifier, or a disperser. The dispersant used here may be a known one such as a surfactant or a polymer dispersant. Both the surfactant and the polymer dispersant can be removed in the washing step described below, but the surfactant is preferred from the viewpoint of washing efficiency.

[0157] Examples of the surfactant 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, nonionic surfactants or anionic surfactants are preferred. In addition, nonionic surfactants and anionic surfactants may be used in combination. The surfactants may be used alone or in combination of two or more. The concentration of the surfactant in the aqueous medium is preferably 0.5% by mass to 5% by mass.

[0158] The content of the colorant particles in the colorant particle dispersion is not particularly limited, but is preferably 1% by mass to 30% by mass with respect to the total mass of the colorant particle dispersion.

[0159] From the viewpoint of dispersibility of the colorant in the toner finally obtained, the dispersed particle size of the colorant particles in the aqueous dispersion of the colorant is preferably 0.5 μm or less in terms of the 50% particle size (D50) based on volume distribution. For the same reason, it is preferable that the 90% particle size (D90) based on volume distribution is 2 μm or less. The dispersed particle size of the colorant particles dispersed in the aqueous medium is measured using a dynamic light scattering particle size distribution meter (Nanotrac UPA-EX150: manufactured by Nikkiso).

[0160] Known mixers such as stirrers, emulsifiers, and dispersers used when dispersing a colorant in an aqueous medium include ultrasonic homogenizers, jet mills, pressure homogenizers, colloid mills, ball mills, sand mills, and paint shakers. These may be used alone or in combination.

[0161] (Release agent (aliphatic hydrocarbon compound) fine particle dispersion) If necessary, a dispersion of releasing agent particles may be used. The dispersion of releasing agent particles can be prepared by the following known methods, but is not limited to these methods.

[0162] A release agent microparticle dispersion can be produced by adding the release agent to an aqueous medium containing a surfactant, heating the mixture to above the melting point of the release agent, dispersing the mixture into particles using a homogenizer with strong shearing capabilities (e.g., M Technique's "Clearmix W Motion") or a pressure discharge type disperser (e.g., Golin Homogenizer) and then cooling the mixture below the melting point of the release agent.

[0163] The particle size of the dispersion of the release agent particles in the aqueous dispersion of the release agent is preferably 50% particle size (D50) based on volume distribution of 0.03 μm to 1.0 μm, more preferably 0.1 μm to 0.5 μm. It is also preferable that no coarse particles of 1 μm or more exist.

[0164] By setting the particle size of the release agent fine particle dispersion within the above range, the release agent can be finely dispersed in the toner, the exudation effect during fixing can be maximized, and good separation properties can be obtained. The particle size of the release agent fine particle dispersion dispersed in the aqueous medium can be measured using a dynamic light scattering particle size distribution analyzer (Nanotrac UPA-EX150: manufactured by Nikkiso).

[0165] "Mixing process" In the mixing step, a mixture is prepared by mixing the resin fine particle dispersion and, if necessary, at least one of the release agent fine particle dispersion and the colorant fine particle dispersion, using a known mixing device such as a homogenizer or a mixer.

[0166] "Step of forming aggregate particles (aggregation step)" In the aggregating step, the fine particles contained in the mixed liquid prepared in the mixing step are aggregated to form aggregates having a desired particle size. At this time, an aggregating agent is added and mixed, and at least one of heating and mechanical power is appropriately applied as necessary to form aggregates in which the resin fine particles and at least one of the release agent fine particles and the colorant fine particles are aggregated as necessary.

[0167] Examples of the flocculant include organic flocculants such as cationic surfactants of quaternary salts and polyethyleneimine; inorganic metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, calcium nitrate; inorganic ammonium salts such as ammonium sulfate, ammonium chloride, ammonium nitrate; and inorganic flocculants such as divalent or higher metal complexes. It is also possible to add an acid to lower the pH and cause soft flocculation, and for example, sulfuric acid, nitric acid, etc. can be used.

[0168] The aggregating agent may be added in the form of either a dry powder or an aqueous solution dissolved in an aqueous medium, but in order to cause uniform aggregation, it is preferable to add it in the form of an aqueous solution. The addition and mixing of the aggregating agent is preferably performed at a temperature equal to or lower than the glass transition temperature or melting point of the resin contained in the mixed liquid. By performing mixing under this temperature condition, the aggregation proceeds relatively uniformly. The mixing of the aggregating agent into the mixed liquid can be performed using a known mixing device such as a homogenizer or a mixer. The aggregation process is a process of forming aggregates of the toner particle size in an aqueous medium. The volume average particle size of the aggregates produced in the aggregation process is preferably 3 μm to 10 μm. The volume average particle size can be measured using a particle size distribution analyzer (Coulter Multisizer III: manufactured by Coulter) using the Coulter method.

[0169] "Process for obtaining a dispersion liquid containing toner particles (fusion process)" In the fusion step, the dispersion containing the aggregates obtained in the aggregation step is first subjected to termination of aggregation under stirring in the same manner as in the aggregation step by adding an aggregation terminator such as a base capable of adjusting the pH, a chelating compound, or an inorganic salt compound such as sodium chloride.

[0170] After the dispersion state of the aggregated particles in the dispersion liquid becomes stable due to the action of the aggregation terminator, the aggregated particles are fused by heating to a temperature equal to or higher than the glass transition temperature or melting point of the binder resin, and the particle size is adjusted to a desired particle size. The 50% particle size (D50) based on volume of the toner particles is preferably 3 μm to 10 μm.

[0171] "Process for obtaining the desired toner surface shape (spheronization process)" During or after the fusion step, it is preferable to further increase the temperature and maintain the temperature until the toner particles reach the desired circularity or surface shape, in a spheronization step.Specific temperatures in the spheronization step are, for example, 90° C. or higher, preferably 92° C. or higher, and preferably 95° C. or lower.The heating time in the spheronization step is, for example, 3 hours or more, 5 hours or more, or 8 hours or more.This step makes it easier to form hydrogen bonds derived from boric acid in the toner particles.

[0172] "Cooling process" After the spheronization step, it is preferable to carry out a cooling step in which the temperature of the dispersion liquid containing the obtained toner particles is cooled to a temperature lower than the crystallization temperature or glass transition temperature of the binder resin by controlling the cooling rate. By carrying out the cooling step, the formation of irregularities on the toner particle surface due to volume changes such as expansion or contraction of the materials in the toner particles is suppressed. The specific cooling rate is 0.1° C. / sec or more, preferably 0.5° C. / sec or more, more preferably 2° C. / sec or more, and even more preferably 4° C. / sec or more.

[0173] "Annealing process" After the cooling step, it is preferable to pass through an annealing step in which the toner particles are heated and held at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin, and, if a release agent is contained, equal to or lower than the crystallization temperature of the release agent. By passing through the annealing step, the volume change can be further suppressed, so that the occurrence of dents on the surface of the toner particles can be suppressed. Therefore, the desired circularity or surface shape obtained through the cooling step can be maintained. The specific annealing temperature is 45°C or higher and 75°C or lower, preferably 50°C or higher and 70°C or lower, and more preferably 55°C or higher and 65°C or lower. The heat treatment time in the annealing step is, for example, within 5 hours, and preferably 2 to 3 hours.

[0174] "Post-processing process" In the toner production method, post-treatment steps such as a washing step, a solid-liquid separation step, and a drying step may be further carried out, and by carrying out the post-treatment steps, toner particles in a dry state are obtained.

[0175] "External addition process" It is preferable that the obtained toner particles are used as a toner by adding external additive particles appropriately.

[0176] In the external addition step, inorganic fine particles are externally added to the toner particles obtained in the drying step. Specifically, in addition to the above-mentioned external additive A, inorganic fine particles such as silica and resin fine particles such as vinyl resin, polyester resin, and silicone resin are preferably added and mixed by applying shear force in a dry state. A known external addition machine can be used as the external addition machine for performing the external addition step.

[0177] As the external addition conditions, the adhesion state of the external additive and the coating state of the toner particles with the external additive can be controlled arbitrarily by changing the rotation speed (rpm) of the stirring blade of the external adder and the external addition time.

[0178] In order to make the particles stick more firmly, it is effective to increase the rotation speed and extend the external addition time, and in particular, it is possible to increase the adhesion strength by increasing the rotation speed. Since the external additive particles having a small particle size form aggregates, the external additive is coated on the toner particles while performing a disintegration process by controlling the external addition conditions. Disintegration can be achieved by increasing the rotation speed and extending the external addition time, but in order to further disintegrate the particles while suppressing the adhesion strength, it is effective to reduce the rotation speed and extend the external addition time.

[0179] In the toner manufacturing method, it is preferable to have a shell forming step in which, after forming aggregated particles (core particles) in an aggregation step, resin fine particles containing a shell resin are further added and aggregated to form a shell. That is, it is preferable that the toner particles have core particles containing a binder resin and a shell on the surface of the core particles. The resin for the shell may be the same as the binder resin, or a different resin may be used. The amount of the resin for the shell added is preferably 5 parts by mass or more and 40 parts by mass or less, more preferably 10 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the binder resin contained in the core particles.

[0180] In this case, the method for producing the toner preferably includes the following steps.

[0181] (1) a dispersion step of preparing a binder resin microparticle dispersion liquid containing a binder resin; (2) an aggregating step of aggregating the binder resin fine particles contained in the binder resin fine particle dispersion to form aggregates; and (3) a fusion step of heating the aggregates to fuse them together That is, the above-mentioned aggregation step (2) (an aggregation step for aggregating the binder resin fine particles contained in the binder resin fine particle dispersion to form aggregates) preferably includes the following steps (2-1) and (2-2). (2-1) an aggregation step of aggregating the binder resin fine particles contained in the binder resin fine particle dispersion to form aggregates; and (2-2) A shell formation step in which resin fine particles containing a shell resin are further added to the dispersion liquid containing the aggregates to aggregate them and form aggregates having a shell. In addition, during or after the fusion step, the following steps (4) to (6) are carried out: (4) a spheronization step of further heating the agglomerates at an elevated temperature; (5) a cooling step of cooling the aggregate at a cooling rate of 0.1° C. / sec or more; and (6) an annealing step of heating and holding the aggregate at a temperature equal to or higher than the crystallization temperature or glass transition temperature of the binder resin; It is more preferable that the compound has the following structures in this order:

[0182] In order to facilitate the incorporation of boron atoms into the toner particles, it is preferred that in the shell formation step, a boron source is added to the dispersion liquid containing the aggregates together with the resin particles containing the shell resin.

[0183] The boron source may be at least one selected from the group consisting of boric acid, borax, organic boric acid, borate, borate ester, etc. For example, a boron source may be added and controlled so that boron is contained in the aggregate. Preferably, the pH is controlled to an acidic condition in the aggregation step, and the shell formation step is carried out.

[0184] The boron source is preferably at least one selected from the group consisting of boric acid and borax. When the toner is produced in an aqueous medium, it is preferable to add a borate as the boron source from the viewpoint of reactivity and production stability. Specifically, the boron source is more preferably at least one selected from the group consisting of sodium tetraborate, borax, ammonium borate, etc., and is even more preferably borax.

[0185] Borax is sodium tetraborate 2 B 4 O 7 Since it is expressed as a decahydrate and changes to boric acid in an acidic aqueous solution, borax is preferably used when used in an aqueous medium under an acidic environment. The addition method may be either in the form of a dry powder or an aqueous solution dissolved in an aqueous medium, but in order to cause uniform aggregation, it is preferable to add it in the form of an aqueous solution. The concentration of the aqueous solution may be appropriately changed depending on the concentration contained in the toner, and is, for example, 1 to 20 mass %. In order to change to boric acid, it is preferable to make the pH an acidic condition before, during, or after the addition. For example, it may be controlled to 1.5 to 5.0, preferably 2.0 to 4.0.

[0186] [Methods for measuring each physical property] Next, the measurement methods for each physical property according to the present disclosure will be described.

[0187] <Measurement of weight average particle size (D4) and number average particle size (D1) of toner or toner particles> The weight-average particle size (D4) and number-average particle size (D1) of the toner or toner particles are measured with a precision particle size distribution measuring device using a pore electrical resistance method equipped with a 100 μm aperture tube, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), and the accompanying dedicated software for setting measurement conditions and analyzing measurement data, "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.), with an effective measurement channel count of 25,000, and the measurement data is analyzed and calculated.

[0188] The electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter).

[0189] Before carrying out the measurements and analyses, the dedicated software is set up as follows.

[0190] In the "Change Standard Measurement Method (SOM) screen" of the dedicated software, set the total count number in the control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. In addition, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the aperture tube flush after measurement.

[0191] In the "Pulse to particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

[0192] The specific measurement method is as follows. (1) Pour about 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, remove dirt and air bubbles from inside the aperture tube using the "Aperture Tube Flush" function of the dedicated software. (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, with a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant. (3) A predetermined amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.) that has two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees and an electrical output of 120 W, and approximately 2 ml of the Conaminon N is added to this water tank. (4) The beaker (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid surface of the electrolyte solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, about 10 mg of toner or toner particles is added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion treatment is continued for another 60 seconds. During the ultrasonic dispersion treatment, the water temperature in the water tank is appropriately adjusted so that it is 10°C or higher and 40°C or lower. (6) Using a pipette, add the electrolytic solution (5) in which the toner or toner particles are dispersed to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to about 5%. Then, measurements are continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight-average particle size (D4) is calculated. Note that when the dedicated software is set to Graph / Volume %, the "average diameter" on the "Analysis / Volume Statistics (Arithmetic Mean)" screen is the weight-average particle size (D4), and when the dedicated software is set to Graph / Number %, the "average diameter" on the "Analysis / Number Statistics (Arithmetic Mean)" screen is the number-average particle size (D1).

[0193] <Method for measuring average circularity of toner (particles)> The average circularity of the toner or toner particles is measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration work.

[0194] Add an appropriate amount of surfactant and alkylbenzene sulfonate as a dispersant to 20 mL of ion-exchanged water, then add 0.02 g of the measurement sample, and disperse for 2 minutes using a tabletop ultrasonic cleaner disperser (product name: VS-150, manufactured by Vervoclear Co., Ltd.) with an oscillation frequency of 50 kHz and an electrical output of 150 watts to obtain a dispersion for measurement. At this time, cool the dispersion appropriately so that the temperature is between 10°C and 40°C.

[0195] For the measurement, the flow type particle image analyzer equipped with a high magnification objective lens (20x) is used, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) is used as the sheath liquid. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 3000 particles are measured in HPF measurement mode and total count mode, and the binarization threshold for particle analysis is set to 85%. In addition, the analysis particle diameter is limited to a circle equivalent diameter of 1.98 μm or more and 19.92 μm or less. By this limitation, external additives that have separated from the toner particle surface during the preparation of the dispersion liquid for measurement can be excluded from the measurement results.

[0196] From the obtained analysis results, the average circularity and the ratio of particles having a circularity of 0.900 or more and 0.930 or less (irregular shape ratio or irregular shape toner ratio) are calculated.

[0197] Before starting the measurement, automatic focus adjustment is performed using standard latex particles (e.g., 5100A (trade name) manufactured by Duke Scientific diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every 2 hours from the start of the measurement.

[0198] <Method of measuring the major axis and aspect ratio of external additive A> The major axis and aspect ratio of external additive A are measured using a scanning electron microscope (for example, scanning electron microscope "S-4800" (product name; manufactured by Hitachi, Ltd.)). The toner to which external additive A has been added is observed in a field of view magnified up to 50,000 times, and the major axis and minor axis of 100 primary particles of external additive A are measured at random. The aspect ratio of external additive A is calculated using the following formula. The observation magnification is adjusted appropriately depending on the size of external additive A. Aspect ratio of external additive A = major axis of external additive A ÷ minor axis of external additive A

[0199] <Method for measuring the proportion of toner particles on whose surface the external additive A is confirmed> The ratio of toner particles that can be confirmed to have the external additive A on their surface is measured using a scanning electron microscope (for example, a scanning electron microscope "S-4800" (product name; manufactured by Hitachi, Ltd.)). 50 toner particles to which external additive A has been added are randomly observed in a field of view magnified about 3000 times so that 10 to 30 toner particles can be observed in one field of view. The ratio of the number of toner particles that have one or more external additives A among the 50 toner particles is calculated, and this is taken as the ratio of toner particles that can be confirmed to have external additive A on their surface. The observation magnification is appropriately adjusted depending on the size of the toner and the size of the external additive A.

[0200] <Measurement of boron content in toner particles> (Method of obtaining toner particles by removing external additives from toner) Add 160 g of sucrose (Kishida Chemical) to 100 mL of ion-exchanged water and dissolve in a hot water bath to prepare a concentrated sucrose solution. In a centrifuge tube (50 mL capacity), add 31 g of the concentrated sucrose solution and 6 mL of Contaminon N (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments with a pH of 7 consisting of nonionic surfactants, anionic surfactants, and organic builders, manufactured by Wako Pure Chemical Industries, Ltd.). Add 1.0 g of toner to this and break up the toner clumps with a spatula or the like. Shake the centrifuge tube at 300 strokes per minute (spm) for 20 minutes in a shaker (AS-1N, sold by AS ONE Corporation). After shaking, transfer the solution to a glass tube for a swing rotor (50 mL) and separate it in a centrifuge (H-9R, manufactured by Kokusan Corporation) at 3,500 rpm for 30 minutes.

[0201] This operation separates the toner particles from the external additives. Visually check that the toner particles and the aqueous solution are sufficiently separated, and collect the toner particles that have separated to the top layer with a spatula or similar. The collected toner particles are filtered through a vacuum filter, and then dried in a dryer for at least one hour to obtain a sample for measurement. This operation is carried out multiple times to ensure the required amount.

[0202] (Boron content in toner particles (ICP-AES)) The boron content in the toner particles is determined by an inductively coupled plasma atomic emission spectrometer (ICP-AES (manufactured by Seiko Instruments Inc.)).

[0203] As a pretreatment, 100.0 mg of toner particles are decomposed with 8.00 ml of 60% nitric acid (Kanto Chemical, for atomic absorption spectrometry). During the acid decomposition, the toner particles are treated in a sealed container at an internal temperature of 220°C for 1 hour using a microwave high-power sample pretreatment device ETHOS1600 (Milestone General Co., Ltd.) to prepare a boron-containing solution sample. After that, ultrapure water is added to make a total of 50.00 g to prepare a measurement sample. A calibration curve is created and the amount of boron contained in each sample is quantified. Note that ultrapure water is added to 8.00 ml of nitric acid to make a total of 50.00 g, which is measured as a blank, and the amount of boron in the blank is subtracted.

[0204] [Configuration included in the embodiment of the present invention] The disclosure of this embodiment includes the following configuration. (Configuration 1) A process cartridge that is detachably mountable to an image forming apparatus, The process cartridge has a developing chamber, The developing chamber comprises: toner, a developing roller for developing an electrostatic latent image using the toner; a regulating member disposed in contact with the developing roller and regulating a layer thickness of the toner carried on the surface of the developing roller; and a toner supply roller arranged in contact with the developing roller and supplying the toner to the developing roller; having the moving direction of the surface of the developing roller is opposite to the moving direction of the surface of the toner supply roller at a contact position between the surface of the developing roller and the surface of the toner supply roller; The developing roller and the toner supply roller have a peripheral speed ratio R represented by the following formula (E1): 1.1≦R≦2.5 It is configured to satisfy R=V RS / V D (E1) (In formula (E1), V RS represents the absolute value of the peripheral speed of the surface of the toner supply roller [m / sec], and V D represents the absolute value of the peripheral speed of the surface of the developing roller [m / sec].) The toner has toner particles and an external additive A, the toner has an average circularity of 0.955 or more and 0.975 or less, and in the circularity distribution of the toner, a ratio of particles existing in the range of 0.900 or more and 0.930 or less is 2.0% by number or more and 15.0% by number or less, The external additive A is a needle-shaped inorganic fine particle having a major axis of 100 nm or more and 3000 nm or less, and when the toner is observed using a scanning electron microscope, the proportion of toner particles on whose surface the external additive A is confirmed is 30% or more by number. A process cartridge comprising: (Configuration 2) The process cartridge according to Configuration 1, wherein the external additive A has an aspect ratio of 5.0 or more. (Configuration 3) The resistivity of the external additive A is 1×10 5 Ω cm or more 1×10 8 3. The process cartridge according to aspect 1 or 2, wherein the resistivity is Ω·cm or less. (Configuration 4) The process cartridge according to any one of Configurations 1 to 3, wherein the external additive A is titanium oxide particles. (Configuration 5) The process cartridge according to Configuration 4, wherein the titanium oxide particles are rutile type titanium oxide particles. (Configuration 6) The process cartridge according to any one of Configurations 1 to 5, wherein the toner particles contain boron, and the boron content is 0.1 ppm by mass or more and 100.0 ppm by mass or less. (Configuration 7) The process cartridge has a toner storage section for storing the toner, the developing chamber has a communication port communicating with the toner storage portion, the toner storage section is disposed vertically below the developing chamber, The process cartridge according to any one of configurations 1 to 6, further comprising a toner transport member that transports the toner contained in the toner container onto the toner supply roller through the communication port provided in the developing chamber. (Configuration 8) The toner transport member has elasticity and transports the toner by rotating, The toner transport member includes: a free end of the toner transport member contacts a wall surface of the toner accommodating section in an area A upstream of the communication opening in a rotation direction of the toner transport member, and the toner transport member is configured to deform against the elasticity as the toner transport member rotates such that the free end side is located upstream of the rotation axis side of the toner transport member in the rotation direction of the transport member, and at a position B downstream of the region A in the rotation direction of the toner transport member and upstream of the communication opening in the rotation direction of the toner transport member, a free end of the toner transport member is released from contact with a wall surface of the toner accommodating section, and the deformed toner transport member is restored by the elasticity so that the transported toner is caused to fly toward the communication opening, The position B is provided below a lower end of the communication port, When viewed from the axial direction of the developing roller, the center of rotation of the toner transport member and the center of rotation of the developing roller are on the same side with respect to a vertical line passing through the position B, 8. The process cartridge according to claim 7, wherein a maximum value of a radius of rotation of the toner transport member is greater than a distance between a center of rotation of the toner transport member and a lower end of the communication port. (Configuration 9) A driving force receiving portion provided on an end portion of the shaft of the toner supply roller; a first driving force transmission portion for transmitting the driving force from the driving force receiving portion to the toner supply roller; The process cartridge according to any one of configurations 1 to 8, further comprising: a second driving force transmission unit provided on the toner supply roller for transmitting the driving force received by the first driving force transmission unit to the developing roller; and a third driving force transmission unit provided on the developing roller for transmitting the driving force from the second driving force transmission unit to the developing roller. (Configuration 10) A process cartridge as described in Configuration 9, wherein, when the radius of the developing roller is rD [mm] and the radius of the toner supply roller is rRS [mm], the second driving force transmission portion and the third driving force transmission portion are drivingly connected so that the rotational angular velocity ratio λ, expressed by the following formula (E2), satisfies 1.1≦λ×rRS / rD≦2.5. λ=ωRS / ωD (E2) (In formula (E2), ωRS represents the rotational angular velocity [rad / sec] of the toner supply roller, and ωD represents the rotational angular velocity [rad / sec] of the developing roller.) (Configuration 11) The process cartridge according to any one of Configurations 1 to 10, wherein the peripheral speed ratio R satisfies 1.2≦R≦1.5. EXAMPLES

[0205] The present disclosure will be described in more detail below using examples and comparative examples. The present disclosure is not limited in any way by the following examples, as long as it does not exceed the gist of the disclosure. In the following description of the examples, "parts" are based on mass unless otherwise specified.

[0206] <Synthesis of polyester resin 1> Bisphenol A-ethylene oxide 2 mole adduct 48 mol parts Bisphenol A-propylene oxide 2 mole adduct 48 mol parts Terephthalic acid 65 mol parts Dodecenylsuccinic acid 30 mol parts The above monomers were added to a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 195°C in one hour, and it was confirmed that the reaction system was uniformly stirred. 0.7 parts of tin distearate were added to 100 parts of these monomers. The temperature was then raised from 195°C to 240°C over five hours while distilling off the water produced, and a dehydration condensation reaction was carried out at 240°C for another two hours. The temperature was then lowered to 190°C, and 5 mol parts of trimellitic anhydride were gradually added, and the reaction was continued at 190°C for one hour.

[0207] As a result, polyester resin 1 having a glass transition temperature of 55.2° C., an acid value of 14.3 mgKOH / g, a hydroxyl value of 24.1 mgKOH / g, a weight average molecular weight of 43,600 and a number average molecular weight of 6,200 was obtained.

[0208] <Preparation of Resin Particle Dispersion 1> 100 parts polyester resin 1 Methyl ethyl ketone 50 parts 20 parts isopropyl alcohol The above methyl ethyl ketone and isopropyl alcohol were added to the container. Then, the above polyester resin 1 was gradually added and stirred to completely dissolve, obtaining a polyester resin 1 solution. The container containing the polyester resin 1 solution was set to 65°C, and a 10% aqueous ammonia solution was gradually dropped to a total of 5 parts while stirring, and 230 parts of ion-exchanged water was gradually dropped at a rate of 10 ml / min to cause phase inversion emulsification. The pressure was then reduced with an evaporator to remove the solvent, obtaining a resin particle dispersion 1 of polyester resin 1. The volume average particle size of the resin particles was 135 nm. The resin particle solid content was adjusted to 20% with ion-exchanged water.

[0209] <Preparation of Colorant Particle Dispersion> Copper phthalocyanine (pigment blue 15:3) 45 parts Anionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts 190 parts deionized water The above components were mixed and dispersed for approximately 1 hour using a high-pressure impact disperser Nanomizer (manufactured by Yoshida Kikai Kogyo) to prepare an aqueous dispersion (colorant microparticle dispersion) containing dispersed colorant with a concentration of 20% colorant microparticles.

[0210] <Preparation of release agent particle dispersion 1> Release agent (HNP-51, melting point 78°C, made by Nippon Seiro) 45 parts Anionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts 190 parts deionized water The above was placed in a mixing vessel equipped with a stirrer, heated to 90°C, and circulated through a Clearmix W Motion (M Technique) for 60 minutes for dispersion treatment. The conditions for dispersion treatment were as follows: Rotor outer diameter 3cm Clearance 0.3mm Rotor speed: 19000 r / min Screen rotation speed: 19000 r / min

[0211] After the dispersion treatment, the mixture was cooled to 40°C under the cooling treatment conditions of a rotor rotation speed of 1000 r / min, a screen rotation speed of 0 r / min, and a cooling rate of 10°C / min, thereby obtaining a release agent particle dispersion 1 having a volume average particle size of 160 nm and a solid content of 20%.

[0212] <Preparation of release agent particle dispersion 2> Release agent (behenyl behenate, melting point 74°C) 45 parts Anionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts 190 parts deionized water The above was placed in a mixing vessel equipped with a stirrer, heated to 90°C, and circulated through a Clearmix W Motion (M Technique) for 60 minutes for dispersion treatment. The conditions for dispersion treatment were as follows: Rotor outer diameter 3cm Clearance 0.3mm Rotor speed: 19000 r / min Screen rotation speed: 19000 r / min

[0213] After the dispersion treatment, the mixture was cooled to 40°C under the cooling treatment conditions of a rotor rotation speed of 1000 r / min, a screen rotation speed of 0 r / min, and a cooling rate of 10°C / min, thereby obtaining a release agent particle dispersion 2 having a volume average particle size of 170 nm and a solid content of 20%.

[0214] <Production of toner suspension particles 1> ·Resin particle dispersion 1 700 parts Colorant particle dispersion 80 parts Release agent particle dispersion 1 30 parts Release agent particle dispersion 2 90 parts 1000 parts of ion-exchanged water First, in the core formation process, the above materials were put into a round stainless steel flask and mixed. Then, the materials were dispersed for 10 minutes at 5000 r / min using a homogenizer Ultra Turrax T50 (manufactured by IKA). After adding a 1.0% nitric acid aqueous solution to adjust the pH to 3.0, the mixture was heated to 45°C in a heating water bath using a stirring blade while appropriately adjusting the rotation speed so that the mixture was stirred.

[0215] The volume average particle size of the formed agglomerated particles was appropriately confirmed using a Coulter Multisizer III. When agglomerated particles (cores) having a particle size of 5.0 μm were formed, the following materials were added as the shell formation step and stirred for another hour to form a shell. ·Resin particle dispersion 1 300 parts 300 parts of ion-exchanged water ·2.0% by mass borax aqueous solution 50 parts (Borax; Sodium tetraborate decahydrate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0216] Thereafter, in the spheronization step, the pH was adjusted to 9.0 using a 5% aqueous sodium hydroxide solution, and the mixture was heated to 90° C. while continuing to stir.

[0217] Thereafter, the average circularity of the formed aggregated particles was appropriately measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation).

[0218] Heating was continued until the average circularity of the aggregated particles reached 0.970 (heating time was 3 hours), and then, as a cooling step, ice was quickly added to cool the mixture to 25°C so that the cooling rate was 10°C / sec or more, thereby obtaining toner suspension particles 1.

[0219] <Production of toner suspension particles 2 to 7> The same procedure as in the production of toner suspension particles 1 was carried out except that the conditions were changed to those shown in Table 1, thereby obtaining toner suspension particles 2 to 7.

[0220] [Table 1]

[0221] <Production of Toner Particle 1> 100 parts of toner suspended particles 1 were filtered and separated into solid and liquid, and then washed with ion-exchanged water. For washing, 200 parts of ion-exchanged water was used for 100 parts of toner suspended particles, and filtration and washing were carried out 20 times. After washing, the particles were dried using a vacuum dryer to obtain toner particles 1 with a weight average particle size (D4) of 6.7 μm. The physical properties of the obtained toner particles 1 are shown in Table 2.

[0222] <Production of Toner Particles 2> 80 parts of toner suspension particles 2 and 20 parts of toner suspension particles 3 were mixed, and then the same procedure as for toner suspension particles 1 was carried out to obtain toner particles 2. The physical properties of the obtained toner particles 2 are shown in Table 2.

[0223] <Production of Toner Particle 3> 80 parts of toner suspension particles 3 and 20 parts of toner suspension particles 1 were mixed, and then the same procedure as for toner suspension particles 1 was carried out to obtain toner particles 3. The physical properties of the obtained toner particles 3 are shown in Table 2.

[0224] <Production of Toner Particles 4 to 8> Toner particles 4 to 8 were obtained in the same manner as toner particles 1, except that the conditions were changed to those shown in Table 2. The physical properties of toner particles 4 to 8 thus obtained are shown in Table 2.

[0225] [Table 2]

[0226] <Production example of external additive 1> Metatitanic acid obtained by the sulfuric acid method was mixed with a 50% NaOH aqueous solution to obtain TiO 2 The mixture was thoroughly washed, and then 31%-HCl was added to the HCl / TiO 2 = 0.26, and heated at boiling point for 1 hour. After cooling, the solution was neutralized to pH 7 with 1N-NaOH, washed and dried to produce fine rutile-type titanium dioxide particles. The specific surface area of ​​the obtained fine rutile-type titanium dioxide particles was 115 g / m 2 It was.

[0227] For 100 parts of this fine rutile titanium dioxide, 100 parts of NaCl and Na 2 P 2 O 7 10H 2 25 parts of O were added and mixed in a vibrating ball mill for 1 hour, and the mixture was calcined in an electric furnace at 850°C for 2 hours. The calcined product was placed in pure water and heated at 80°C for 6 hours, and then washed to remove soluble salts. All of the particles obtained after drying were fine needle-shaped titanium oxide particles with minor axis diameters in the range of 0.03 to 0.07 μm and major axis diameters in the range of 0.4 to 0.8 μm.

[0228] For each 1000 kg of the base material, 100 g each of methyltrimethoxysilane and trimethoxyfluorosilane and 5 kg of toluene were added to prepare a slurry, which was then thoroughly mixed with a stirrer and further processed using a horizontal continuous sand grinder mill. The processed slurry was then placed in a kneader and dried under reduced pressure to obtain hydrophobic titanium oxide particles (external additive 1). The physical properties of the obtained external additive 1 are shown in Table 3.

[0229] <Production Examples of External Additives 2 to 12> External additives 2 to 12 were obtained in the same manner as in the production example of external additive 1, except that the conditions were changed to those in Table 3. The physical properties of the obtained external additives 2 to 12 are shown in Table 3.

[0230] [Table 3]

[0231] <Production Example of External Additive 13> The external additive 13 is silica particles, and the BET specific surface area of ​​the original material is 170 m 2 / g silica particles were subjected to hydrophobic treatment using hexamethyldisilazane.

[0232] <Toner 1 Manufacturing Example> Toner particles 1 100.0 parts Additive 1 (equivalent to Additive A) 0.60 parts External additive 13 0.80 parts The above materials were mixed at 3000 rpm for 15 minutes using a Henschel mixer (manufactured by Nippon Coke Corporation) to obtain toner 1. When the toner was observed using a scanning electron microscope, the proportion of toner particles on whose surfaces the external additive A was confirmed to be present was 70% by number.

[0233] <Production Examples of Toners 2 to 21> Toners 2 to 21 were obtained in the same manner as in the production example of toner 1 except for changing the conditions in Table 4. The ratio of toner particles on which the external additive A was confirmed to be present on the surface was as shown in Table 4.

[0234] [Table 4]

[0235] Example 1 Using the above toner 1, evaluation was carried out under low temperature and low humidity environmental conditions of a temperature of 15° C. and a humidity of 10% RH.

[0236] For the evaluation, a modified HP Laserjet Enterprise 6701dn laser beam printer was used. The software of the evaluation machine was changed to set the process speed to 650 mm / sec. The cartridge gear was also changed to set the rotation direction of the developing roller and toner supply roller at the contact point in the opposite direction and R to 1.3. The cartridge was filled with 200 g of evaluation toner before the evaluation.

[0237] [Evaluation of development streaks] Using the modified evaluation machine and modified cartridge, a durability test was conducted by continuously printing 10,000 sheets of horizontal lines with an image ratio of 1%, and then a solid black image was printed. The printed solid black image and the developing roller were visually inspected to confirm the occurrence of development streaks. The evaluation results are shown in Table 5. (Evaluation Criteria) A: No development streaks occurred. B: No streaks occurred on the solid black image, but several slight streaks occurred on the developing roller. C: Three or fewer development streaks appear on a solid black image. D: Four or more development streaks appear on a solid black image.

[0238] [Ghost Rating] Using the modified evaluation machine and modified cartridge, 10,000 sheets of horizontal lines with an image ratio of 1% were continuously printed on each sheet for durability testing, and then a monochrome ghost evaluation image was output. The ghost evaluation image was a 15 mm x 15 mm solid image with 7 solid images of 15 mm x 15 mm arranged in a horizontal row at 15 mm intervals at a position 5 mm from the top edge of the transfer paper, and the area below these solid images was printed with a toner loading amount of 0.20 mg / cm. 2 The halftone image was made of 15 mm×15 mm solid image. The density difference caused by the 15 mm×15 mm solid image in the halftone portion of the image was visually evaluated. The results are shown in Table 5. In this evaluation, rank B or higher was determined to be an indication of the effects of the present disclosure. (Evaluation Criteria) A: No difference in shading is observed. B: Slight differences in shading are observed. C: Differences in shade are observed, which is problematic for practical use. D: The difference in shade is clearly observed, which is problematic for practical use.

[0239] [Evaluation of charge build-up] Using the modified evaluation machine and modified cartridge described above, two solid images were printed in monochrome before the durability test. For the second image, density measurements were performed at 20 points, and the initial charge rise property was evaluated based on the difference in density between the maximum and minimum values ​​(referred to as density uniformity) using the following evaluation criteria. The density was measured using an X-Rite color reflection densitometer (X-rite 500 Series, manufactured by X-rite). The initial density uniformity on the second sheet and the density uniformity after durability on the 10,000th sheet were evaluated using the following evaluation criteria. The evaluation results are shown in Table 5. (Evaluation Criteria) A: Density uniformity is less than 0.04. B: Density uniformity is 0.04 or more and less than 0.07. C: Density uniformity is 0.07 or more and less than 0.10. D: Density uniformity is 0.10 or more.

[0240] [Examples 2 to 21, Comparative Examples 1 to 7] The evaluation was performed in the same manner as in Example 1, except that the toner used, the moving direction of the developing roller and the toner supply roller, and R were set as shown in Table 5. The evaluation results of Examples 2 to 21 and Comparative Examples 1 to 7 are shown in Table 5.

[0241] [Table 5] [Explanation of symbols]

[0242] 1 photosensitive drum, 2 charging roller, 3 scanner unit, 4 developing unit, 5 intermediate transfer unit, 6 cleaning member, 7 elastic member made of rubber blade, 8 cleaning blade support member, 17 cassette containing recording medium S, 25 developing roller, 25e developing roller rotation center, 26 cleaning unit, 27 removed toner chamber, 31 developing frame, 31a toner storage chamber, 31b developing chamber, 34 toner supply roller, 34e toner supply roller rotation center, 35 developing blade (regulating member), 35a developing blade support plate, 35b flexible plate-shaped member, 36 toner conveying member, 36a stirring shaft, 36b sheet member, 50 transfer belt, 55 registration roller, 56 driving roller, 57 driven roller, 58 primary transfer roller, 59 opposing roller, 69 secondary transfer roller, 70 process cartridge, 72 discharge roller, 74 Fixing section, 75 Discharge section, 100 Image forming apparatus, 201 Coupling, 202 Intermediate body, 203 Drive transmission section, 204 Gear, 204a Third drive transmission section, 204b Idler gear, 204c Second drive transmission section, 811 First section, 812 Second section, 813 Third section, 818 Leading edge section

Claims

1. A process cartridge that is detachably mountable to an image forming apparatus, The process cartridge has a developing chamber, The developing chamber comprises: toner, a developing roller for developing an electrostatic latent image using the toner; a regulating member disposed in contact with the developing roller and regulating a layer thickness of the toner carried on the surface of the developing roller; and a toner supply roller arranged in contact with the developing roller and supplying the toner to the developing roller; having the moving direction of the surface of the developing roller is opposite to the moving direction of the surface of the toner supply roller at a contact position between the surface of the developing roller and the surface of the toner supply roller; The developing roller and the toner supply roller have a peripheral speed ratio R represented by the following formula (E1): 1.1≦R≦2.5 It is configured to satisfy R=V RS / V D (E1) (In formula (E1), V RS represents the absolute value of the peripheral speed of the surface of the toner supply roller [m / sec], and V D represents the absolute value of the peripheral speed of the surface of the developing roller [m / sec].) The toner has toner particles and an external additive A, the toner has an average circularity of 0.955 or more and 0.975 or less, and in the circularity distribution of the toner, a ratio of particles present in the range of 0.900 or more and 0.930 or less is 2.0% by number or more and 15.0% by number or less, The external additive A is an acicular inorganic fine particle having a major axis of 100 nm to 3000 nm, and when the toner is observed using a scanning electron microscope, the proportion of toner particles on whose surfaces the external additive A is confirmed to be present is 30% by number or more. A process cartridge comprising:

2. 2. The process cartridge according to claim 1, wherein the external additive A has an aspect ratio of 5.0 or more.

3. The resistivity of the external additive A is 1×10 5 Ω・cm or more 1×10 8 3. The process cartridge according to claim 1, wherein the surface roughness is Ω·cm or less.

4. 3. The process cartridge according to claim 1, wherein said external additive A is titanium oxide particles.

5. 5. The process cartridge according to claim 4, wherein the titanium oxide particles are rutile type titanium oxide particles.

6. 3. The process cartridge according to claim 1, wherein the toner particles contain boron, and the boron content is from 0.1 ppm by mass to 100.0 ppm by mass.

7. the process cartridge has a toner storage section for storing the toner, the developing chamber has a communication port communicating with the toner storage portion, the toner storage section is disposed vertically below the developing chamber, 3. The process cartridge according to claim 1, further comprising a toner transport member that transports the toner contained in the toner container onto the toner supply roller through the communication port provided in the developing chamber.

8. the toner transport member is a member that has elasticity and transports the toner by rotating, The toner transport member includes: a free end of the toner transport member contacts a wall surface of the toner accommodating section in an area A upstream of the communication opening in a rotation direction of the toner transport member, and the toner transport member is deformed against the elasticity as the toner transport member rotates such that the free end side is located upstream of the rotation axis side of the toner transport member in the rotation direction of the transport member, and at a position B downstream of the region A in the rotation direction of the toner transport member and upstream of the communication opening in the rotation direction of the toner transport member, a free end of the toner transport member is released from contact with a wall surface of the toner accommodating portion, and the deformed toner transport member is restored by the elasticity so that the transported toner is caused to fly toward the communication opening, The position B is provided below a lower end of the communication port, When viewed from the axial direction of the developing roller, the center of rotation of the toner transport member and the center of rotation of the developing roller are on the same side of a vertical line passing through the position B, 8. The process cartridge according to claim 7, wherein a maximum value of a radius of rotation of said toner transport member is greater than a distance between a center of rotation of said toner transport member and a lower end of said communication port.

9. a driving force receiving portion provided at an end of the shaft of the toner supply roller; a first driving force transmitting portion for transmitting a driving force from the driving force receiving portion to the toner supply roller; 3. The process cartridge according to claim 1, further comprising: a second driving force transmission portion provided on the toner supply roller for transmitting the driving force received by the first driving force transmission portion to the developing roller; and a third driving force transmission portion provided on the developing roller for transmitting the driving force from the second driving force transmission portion to the developing roller.

10. 10. The process cartridge according to claim 9, wherein, when a radius of the developing roller is rD [mm] and a radius of the toner supply roller is rRS [mm], the second driving force transmission portion and the third driving force transmission portion are drivingly connected so that a rotational angular velocity ratio λ expressed by the following formula (E2) satisfies 1.1≦λ×rRS / rD≦2.5: λ=ωRS / ωD (E2) (In formula (E2), ωRS represents the rotational angular velocity [rad / sec] of the toner supply roller, and ωD represents the rotational angular velocity [rad / sec] of the developing roller.)

11. 3. The process cartridge according to claim 1, wherein the peripheral speed ratio R satisfies 1.2≦R≦1.5.

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