Image forming device

Abstract

The present invention provides an image forming device that suppresses the occurrence of deviation in low-temperature fixability. An image forming device, comprising: an electrophotographic photoreceptor; an electrostatic image forming unit; a developing unit that contains an electrostatic image developer containing a toner for electrostatic image development, and develops the toner image formed on the surface of the electrophotographic photoreceptor by the electrostatic image developer; a transfer unit; and a fixing unit, the fixing unit having a fixing belt, a rotating body, and a heating source, the toner for electrostatic image development containing toner particles and silicon oxide particles, the silicon oxide particles having a number average particle size of 110 nm or more and 130 nm or less, a large diameter side number particle size distribution index (upper side GSDp) of less than 1.080, an average circularity of 0.94 or more and 0.98 or less, and a proportion of particles having a circularity of 0.92 or more of 80% or more.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus. Background Art

[0002] Japanese Patent Gazette No. 2002-099171 discloses "a fixing device comprising: a first fixing roller; a rotating roller arranged to maintain a predetermined interval with the fixing roller; an endless belt wound around the first fixing roller and the rotating roller and rotated; and a second fixing roller pressed against the first fixing roller in a manner of sandwiching the endless belt, wherein the fixing device is characterized in that the endless belt is rotated by a driving force from the first fixing roller."

[0003] Japanese Patent Gazette No. 2006-047768 discloses "a fixing device comprising: an annular fixing belt, a central portion in the width direction of which is in a tension-free state in the circumferential direction and is supported so as to be able to move in a circumferential direction; a heating device that heats the fixing belt; a pressure roller that abuts against the outer circumferential surface of the fixing belt and is supported so as to be able to rotate around an axis; a pressing member that abuts against the inner circumferential surface of the fixing belt and causes a pressing force to act between the pressing member and the pressure roller via the fixing belt; and a supporting member that is inserted through the inner side of the fixing belt and supports the pressing member, the fixing device presses and heats an unfixed toner image on a recording medium passing through a fixing nip formed between the fixing belt and the pressure roller, thereby forming a fixed image, wherein the circumferential shape of the fixing belt near both side edges is maintained in a circular shape, and the fixing belt is supported so as to be able to rotate around the center axis with both end portions of the supporting member as the center axis."

[0004] Japanese Patent Application Publication No. 2011-507049 discloses "an electrophotographic toner, comprising: toner mother particles comprising a binding resin, a colorant, a release agent and a charge control agent; and a barium titanate external additive added to the surface of the toner mother particles, the primary average particle size of which is 50 to 150 nm, the average shape factor (SF1) is 100 to 120, the shape factor is 0.96 to 1, and the aspect ratio is 0.89 to 1." Summary of the invention

[0005] An image forming device (hereinafter also referred to as a "specific image forming device") is known, which comprises: an electrophotographic photosensitive body; an electrostatic image forming unit; a developing unit, which contains an electrostatic image developer containing a toner for electrostatic image development, and develops the electrostatic image formed on the surface of the electrophotographic photosensitive body into a toner image for electrostatic image development through the electrostatic image developer; a transfer unit; and a fixing unit, which fixes the toner image transferred to the surface of a recording medium to the recording medium, the fixing unit having: a fixing belt, which contacts the toner image transferred to the surface of the recording medium; a rotating body, which contacts the outer peripheral surface of the fixing belt and is arranged in a manner to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to transport the recording medium; and a heating source, which heats the contact area between the fixing belt and the rotating body.

[0006] In a specific conventional image forming apparatus, there may be variations in low-temperature fixing properties.

[0007] Therefore, the subject of the present application is to provide an image forming device, which suppresses the deviation of low-temperature fixing property compared with a specific image forming device that only contains silica particles with an average particle size of more than 110nm and less than 130nm and a large-diameter side particle size distribution index (upper side GSDp) of more than 1.080 as an external additive in a toner for electrostatic image development.

[0008] According to a first aspect of the present application, there is provided an image forming apparatus comprising:

[0009] An electrophotographic photoreceptor having a photosensitive layer;

[0010] an electrostatic image forming unit that forms an electrostatic image on the surface of the charged electrophotographic photoreceptor;

[0011] a developing unit containing an electrostatic image developer including a toner for developing an electrostatic image, and developing a toner image formed on the surface of the electrophotographic photoreceptor by the electrostatic image developer;

[0012] a transfer unit that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium; and

[0013] a fixing unit that fixes the toner image transferred onto the surface of the recording medium to the recording medium;

[0014] The fixing unit comprises:

[0015] a fixing belt in contact with the toner image transferred to the surface of the recording medium;

[0016] a rotating body that contacts the outer peripheral surface of the fixing belt and is provided so as to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to transport the recording medium; and

[0017] a heating source that heats the contact area between the fixing belt and the rotating body,

[0018] The electrostatic image developing toner contains toner particles and silica particles, wherein the silica particles have a number average particle size of 110 nm to 130 nm, a large diameter side number particle size distribution index, i.e., an upper side GSDp, less than 1.080, an average roundness of 0.94 to 0.98, and a proportion of particles with a roundness of 0.92 or more of 80% by number or more.

[0019] According to a second aspect of the present application, in the image forming apparatus described in [1], the silica particles have an upper GSDp, which is an index of the larger diameter side number size distribution, of less than 1.075.

[0020] According to the third aspect of the present application, the silica particles have a smaller diameter side number size distribution index, that is, a lower GSDp, which is less than 1.080.

[0021] According to a fourth aspect of the present application, the average circularity of the silica particles is 0.95 or more and 0.97 or less.

[0022] According to the fifth aspect of the present application, the ratio of the silica particles having the circularity of 0.92 or more is 85% by number or more.

[0023] According to a sixth aspect of the present application, the electrostatic image developing toner further includes inorganic oxide particles having a number average particle diameter of 5 nm or more and 50 nm or less.

[0024] According to a seventh aspect of the present application, the toner particles contain a styrene acrylic resin as a binder resin.

[0025] According to an eighth aspect of the present application, the toner particles contain a non-crystalline polyester resin as a binder resin.

[0026] According to the 9th scheme of the present application, the fixing unit also has a pressure-applying component, which is arranged on the inner peripheral surface side of the fixing belt and pressurizes the fixing belt together with the rotating body in the contact area, and the heating source is a heating source that heats the contact area through the pressure-applying component.

[0027] According to a tenth aspect of the present application, the heating source is a halogen lamp.

[0028] According to the eleventh aspect of the present application, the image forming apparatus includes a reflecting member configured to reflect the radiant heat from the halogen lamp toward the contact region.

[0029] According to the twelfth aspect of the present application, a heat insulating member is provided between the side edge of the reflecting member and the inner peripheral surface of the fixing belt facing the side edge.

[0030] According to a thirteenth aspect of the present application, the fixing unit includes a pressing member on a downstream side of the contact region, and the pressing member presses the rotating body from the inner side of the fixing belt.

[0031] According to a fourteenth aspect of the present application, the rotating body has an elastic layer on a surface on a side pressed against the fixing belt.

[0032] According to a fifteenth aspect of the present application, the pressing member is configured to elastically deform the elastic layer.

[0033] According to a sixteenth aspect of the present application, the pressing member is arranged to elastically deform the elastic layer locally on the discharge side of the fixing unit.

[0034] According to a seventeenth aspect of the present application, the heating source is a linear heating element.

[0035] According to an eighteenth aspect of the present application, the fixing unit includes a current supplying portion for supplying pulse current to the linear heating element.

[0036] According to the 19th scheme of the present application, the fixing unit further comprises: a sliding member that slides with the linear heating element; an energizing section that performs pulse energization on the linear heating element; and a cooling section that cools the fixed image after the toner image transferred to the surface of the recording medium is fixed.

[0037] The contact region is heated from the linear heating element via the sliding member.

[0038] According to a 20th aspect of the present application, the fixing unit is an electromagnetic induction heating fixing unit.

[0039] According to a 21st aspect of the present application, the fixing unit includes an electromagnetic induction heating device, and a metal layer is provided inside the fixing belt as the heating source.

[0040] Effects of the Invention

[0041] According to the above-mentioned scheme 1, 7 or 8, an image forming device is provided, which suppresses the deviation of low-temperature fixing property compared with a case in which a specific image forming device only contains silica particles with an average particle size of not less than 110nm and not more than 130nm and a large-diameter side particle size distribution index (upper side GSDp) of not less than 1.080 as an external additive in a toner for electrostatic image development.

[0042] According to the second aspect, there is provided an image forming apparatus in which the occurrence of variation in low-temperature fixing performance is further suppressed compared to a case where the large-diameter side number particle size distribution index (upper GSDp) is 1.075 or more.

[0043] According to the third aspect, there is provided an image forming apparatus in which the occurrence of variation in low-temperature fixing performance is further suppressed compared to a case where the smaller-diameter side number particle size distribution index (lower side GSDp) is 1.080 or more.

[0044] According to the fourth aspect, there is provided an image forming apparatus which can further suppress the occurrence of variations in low-temperature fixability and streak-like image defects compared to the case where the average circularity is less than 0.95 or exceeds 0.97.

[0045] According to the fifth aspect, there is provided an image forming apparatus in which the occurrence of variation in low-temperature fixing performance is further suppressed compared to a case where the proportion of the particles having a circularity of 0.92 or more is less than 85% by number.

[0046] According to the sixth aspect, there is provided an image forming apparatus in which the occurrence of variation in low-temperature fixability is further suppressed compared with a case where inorganic oxide particles having a number average particle size of less than 5 nm or exceeding 50 nm are included.

[0047] According to the above-mentioned schemes 9, 10, 11, 12, 13, 14, 15 or 16, an image forming device is provided, which has the following fixing unit, compared with the case where a specific image forming device has a double-roller type fixing unit, thereby suppressing the deviation of low-temperature fixing performance, the fixing unit has a pressure-applying component that is arranged on the inner circumferential surface side of the fixing belt and presses the fixing belt together with the rotating body in the contact area, and the heating source heats the contact area through the pressure-applying component.

[0048] According to the above-mentioned scheme 17, 18 or 19, an image forming device is provided, which has a fixing unit having a linear heating element as a heating source, thereby achieving low-temperature fixing performance compared to the case where a specific image forming device has a double-roller type fixing unit.

[0049] According to the 20th or 21st aspect, there is provided an image forming apparatus in which, compared with a case where a specific image forming apparatus has a twin-roller fixing unit, the fixing unit includes an electromagnetic induction fixing unit, thereby suppressing the occurrence of variations in low-temperature fixing properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 1 is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0051] Figure 2 This is a schematic structural diagram showing an example of the fixing device according to the first embodiment.

[0052] Figure 3 This is a schematic structural diagram showing an example of a fixing device according to the second embodiment.

[0053] Figure 4 It is a schematic structural diagram showing an example of a fixing device according to a third embodiment.

[0054] Figure 5 It is a schematic structural diagram showing an example of a fixing device according to a fourth embodiment.

[0055] Figure 6 It is a schematic structural diagram showing another example of the fixing device according to the fourth embodiment. DETAILED DESCRIPTION

[0056] The following describes embodiments of the present application. These descriptions and examples illustrate the embodiments and do not limit the scope of the embodiments.

[0057] In the numerical range of recording in stages in the application, the upper limit or lower limit recorded by a numerical range can also be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range of recording in the application, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment.

[0058] In the present application, each component may include a plurality of corresponding substances. When the amount of each component in the composition is mentioned in the present application, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0059] Image forming device

[0060] The image forming device involved in this embodiment comprises: an electrophotographic photoreceptor having a photosensitive layer; an electrostatic image forming unit, which forms an electrostatic image on the surface of the charged electrophotographic photoreceptor; a developing unit, which accommodates an electrostatic image developer containing a toner for developing the electrostatic image, and develops the toner image formed on the surface of the electrophotographic photoreceptor by the electrostatic image developer; a transfer unit, which transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium; and a fixing unit, which fixes the toner image transferred to the surface of the recording medium to the recording medium.

[0061] The fixing unit includes: a fixing belt that contacts the toner image transferred to the surface of the recording medium; a rotating body that contacts the outer peripheral surface of the fixing belt, is arranged in a manner to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to transport the recording medium; and a heating source that heats the contact area between the fixing belt and the rotating body.

[0062] For a toner for electrostatic image development, the toner for electrostatic image development contains toner particles and silica particles, the number average particle size of the silica particles is greater than 110 nm and less than 130 nm, the large diameter side number particle size distribution index (upper side GSDp) is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of particles with a roundness of greater than 0.92 is greater than 80% by number.

[0063] Hereinafter, the image forming apparatus according to the present embodiment is also referred to as a “specific image forming apparatus”.

[0064] The silica particles having the above-mentioned characteristics are also referred to as "first silica particles".

[0065] The electrophotographic photoreceptor is also referred to as a "photoreceptor".

[0066] The electrostatic image developing toner is also referred to as “toner”.

[0067] Conventionally, there is known an image forming device including a fixing unit, such as the above-mentioned specific image forming device, which includes: a fixing belt that contacts a toner image transferred to a surface of a recording medium; a rotating body that contacts an outer peripheral surface of the fixing belt and is provided so as to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to convey the recording medium; and a heating source that heats the contact area between the fixing belt and the rotating body. The specific image forming device includes a heating source that heats the contact area, and thus can quickly increase the fixing temperature while suppressing power consumption, thereby fixing the toner image at a low temperature.

[0068] However, a specific image forming apparatus may have variations in low-temperature fixing properties depending on the composition of the toner contained therein. Although the reason for this is not necessarily clear, it can be estimated as follows.

[0069] In an image forming apparatus, a toner containing toner particles and silica particles as an external additive is stored in order to improve cleaning assistance and fixing performance.

[0070] In the past, in a specific image forming device, if large-diameter or irregular-shaped silica particles are added to toner particles from the outside, there is a tendency that the heat energy transfer from the heating source to the toner particles is hindered in the fixing process. On the other hand, in a specific image forming device, if small-diameter or perfect-spherical silica particles are added to toner particles from the outside, there is a tendency that the small-diameter silica particles roll and aggregate on the surface of the toner particles, thereby making it difficult for the silica particles to function as an external additive. As a result, deviations sometimes occur in low-temperature fixing properties.

[0071] On the other hand, the image forming apparatus according to the present embodiment accommodates the toner having the above-described configuration in which first silica particles are externally added to toner particles.

[0072] The number average particle size of the first silica particles is less than 130 nm, the number particle size distribution index on the large diameter side (upper GSDp) is less than 1.080, the average roundness is greater than 0.94, and the proportion of particles with a roundness of greater than 0.92 is greater than 80%. That is, the first silica particles are silica particles with a moderate particle size and a small number of large-diameter and irregular-shaped particles. Therefore, there is a tendency that even if the particles are added externally to the toner particles, the heat energy transfer from the heating source to the toner particles is hardly hindered in the fixing step. In addition, the number average particle size of the first silica particles is greater than 110 nm, and the average roundness is less than 0.98. That is, the first silica particles are silica particles with a moderate particle size and a small number of small-diameter and true-ball particles. Therefore, there is a tendency that even if the particles are added externally to the toner particles, the rolling and aggregation of the small-diameter silica particles on the surface of the toner particles can be suppressed. As a result, it is considered that the occurrence of variation in low-temperature fixing performance can be suppressed also in a specific image forming apparatus.

[0073] [Specific example of image forming apparatus]

[0074] The image forming device involved in this embodiment is applicable to the following well-known image forming devices: a direct transfer device, in which the toner image formed on the surface of the electronic photographic photosensitive body is directly transferred to the recording medium; an intermediate transfer device, in which the toner image formed on the surface of the electronic photographic photosensitive body is transferred once to the surface of the intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is transferred secondarily to the surface of the recording medium; and a device equipped with a static elimination device, which irradiates the surface of the electronic photographic photosensitive body with static elimination light after the transfer of the toner image and before charging to eliminate static electricity; and the like.

[0075] In the case of an intermediate transfer device, the transfer device, for example, is configured to include an intermediate transfer body, a primary transfer component, and a secondary transfer component. The intermediate transfer body has a toner image transferred on its surface, the primary transfer component transfers the toner image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body, and the secondary transfer component transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0076] In addition, in the image forming apparatus according to the present embodiment, for example, at least the portion including the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus.

[0077] Hereinafter, an image forming apparatus according to the present embodiment will be described with reference to the drawings.

[0078] Figure 1 This is a schematic structural diagram showing a structure of an example of the image forming apparatus according to the present embodiment.

[0079] like Figure 1 As shown, the image forming apparatus 100 according to the present embodiment is, for example, an image forming apparatus of an intermediate transfer method generally called a tandem type, and includes: a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components by an electrophotographic method; a primary transfer section 10 that sequentially transfers (primarily transfers) the toner images of respective color components formed by the image forming units 1Y, 1M, 1C, and 1K to an intermediate transfer belt 15; a secondary transfer section 20 that transfers (secondarily transfers) the superimposed toner images transferred to the intermediate transfer belt 15 to a sheet of paper K as a recording medium; and a fixing device 60 (an example of a fixing unit) that fixes the secondary transferred image to the sheet of paper K. In addition, the image forming apparatus 100 includes a control section 40 that exchanges information with each device (each unit) and controls the operation of each device (each unit).

[0080] It should be noted that a unit including the intermediate transfer belt 15 , the primary transfer section 10 , and the secondary transfer section 20 corresponds to an example of a transfer unit.

[0081] Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photoreceptor 11 that rotates in the direction of arrow A as an example of an electrophotographic photoreceptor that holds a toner image formed on the surface.

[0082] Around the photoconductor 11, a charger 12 for charging the photoconductor 11 is provided as an example of a charging unit, and a laser exposer 13 (the exposure beam is represented by the symbol Bm in the figure) for writing an electrostatic image on the photoconductor 11 is provided as an example of an electrostatic image forming unit.

[0083] In addition, around the photosensitive body 11, there is provided a developer 14 as an example of a developing unit for accommodating toners of each color component and visualizing the electrostatic image on the photosensitive body 11 through the toners, and a primary transfer roller 16 for transferring the toner images of each color component formed on the photosensitive body 11 to the intermediate transfer belt 15 through the primary transfer section 10.

[0084] It should be noted that the above-mentioned specific toner is used as at least one of the above-mentioned color component toners. In the present embodiment, it is preferable that all the color component toners are the above-mentioned specific toners.

[0085] Furthermore, a photoreceptor cleaner 17 for removing residual toner on the photoreceptor 11 is provided around the photoreceptor 11, and the electrophotographic devices of the charger 12, the laser exposure device 13, the developer 14, the primary transfer roller 16, and the photoreceptor cleaner 17 are arranged in sequence along the rotation direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially linear manner in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15.

[0086] The intermediate transfer belt 15 passes through various rollers and Figure 1 The intermediate transfer belt 15 is cyclically driven (rotated) at a speed suitable for the purpose in the direction B shown. The various rollers include: a driving roller 31 that is driven by a motor (not shown) to rotate the intermediate transfer belt 15; a supporting roller 32 that supports the intermediate transfer belt 15 that extends substantially linearly along the arrangement direction of the photosensitive bodies 11; a tension applying roller 33 that applies tension to the intermediate transfer belt 15 and functions as a correction roller that suppresses the meandering of the intermediate transfer belt 15; a back roller 25 that is provided in the secondary transfer section 20; and a cleaning back roller 34 that is provided in the cleaning section that scrapes off the residual toner on the intermediate transfer belt 15.

[0087] The primary transfer section 10 is composed of a primary transfer roller 16 as an opposing member disposed opposite to the photosensitive body 11 with the intermediate transfer belt 15 sandwiched therebetween. The primary transfer roller 16 is composed of a core body and a sponge layer as an elastic layer fixed to the periphery of the core body. The core body is a cylindrical rod made of a metal such as iron or SUS. The sponge layer is formed of a blended rubber of NBR, SBR, and EPDM mixed with a conductive agent such as carbon black, and has a volume resistivity of 10 7.5 Ωcm or more and 10 8.5 Sponge-like cylindrical roller with a thickness of Ωcm or less.

[0088] The primary transfer roller 16 is placed in pressure contact with the photoreceptor 11 with the intermediate transfer belt 15 interposed therebetween, and a voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner (negative polarity, the same applies hereinafter) is applied to the primary transfer roller 16. As a result, the toner images on the respective photoreceptors 11 are electrostatically attracted to the intermediate transfer belt 15 in sequence, thereby forming overlapping toner images on the intermediate transfer belt 15.

[0089] The secondary transfer section 20 includes a back roller 25 and a secondary transfer roller 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 .

[0090] The surface of the back roller 25 is made of a tube of a blended rubber of EPDM and NBR in which carbon is dispersed, and the inside is made of EPDM rubber. 7 Ω / □More than 10 10 The back roller 25 is arranged on the back side of the intermediate transfer belt 15, constitutes the counter electrode of the secondary transfer roller 22, and is in contact with a metal power supply roller 26 that stably applies the secondary transfer bias.

[0091] On the other hand, the secondary transfer roller 22 is composed of a core body and a sponge layer as an elastic layer fixed around the core body. The core body is a cylindrical rod made of metal such as iron and SUS. The sponge layer is formed of a blended rubber of NBR, SBR and EPDM with a conductive agent such as carbon black, and has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 Sponge-like cylindrical roller with a thickness of Ωcm or less.

[0092] The secondary transfer roller 22 is pressed against the back roller 25 with the intermediate transfer belt 15 sandwiched therebetween, and the secondary transfer roller 22 is grounded to form a secondary transfer bias between the back roller 25 and the back roller 25, so as to transfer the toner image to a sheet of paper (an example of a recording medium) K conveyed to the secondary transfer section 20.

[0093] In addition, on the downstream side of the secondary transfer section 20 of the intermediate transfer belt 15, an intermediate transfer belt cleaner 35 is provided in a manner that can freely contact and separate, and removes residual toner and paper powder on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15.

[0094] It should be noted that the intermediate transfer belt 15 , the primary transfer section 10 (primary transfer roller 16 ), and the secondary transfer section 20 (secondary transfer roller 22 ) correspond to an example of a transfer unit.

[0095] On the other hand, a reference sensor (home position sensor) 42 is disposed on the upstream side of the yellow image forming unit 1Y, and generates a reference signal that serves as a reference for obtaining the image forming timing of each image forming unit 1Y, 1M, 1C, and 1K. In addition, an image density sensor 43 for image quality adjustment is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 is configured to recognize a mark provided on the back side of the intermediate transfer belt 15 and generate a reference signal, and each image forming unit 1Y, 1M, 1C, and 1K starts image formation according to an instruction from the control unit 40 based on the recognition of the reference signal.

[0096] Furthermore, in the image forming apparatus involved in the present embodiment, as a conveying unit for conveying paper K, it is provided with: a paper containing section 50, which contains paper K; a paper supply roller 51, which takes out the paper K stacked in the paper containing section 50 at a predetermined timing and conveys it; a conveying roller 52, which conveys the paper K sent out by the paper supply roller 51; a conveying guide 53, which feeds the paper K conveyed by the conveying roller 52 into the secondary transfer section 20; a conveying belt 55, which conveys the paper K conveyed after the secondary transfer by the secondary transfer roller 22 to the fixing device 60 (an example of a fixing unit); and a fixing entrance guide 56, which guides the paper K to the fixing device 60.

[0097] The control unit 40 is configured as a computer that controls the entire device and performs various calculations. Specifically, for example, the control unit 40 includes: a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores various programs, a RAM (Random Access Memory) that is used as a work area when the program is executed, a non-volatile memory that stores various information, and an input / output interface (I / O) (none of which are shown in the figure). The CPU, ROM, RAM, non-volatile memory, and I / O are connected via buses.

[0098] It should be noted that the image forming apparatus 100 includes an operation display unit, an image processing unit, an image memory, a storage unit, and a communication unit (all not shown) in addition to the control unit 40. Each of the operation display unit, the image processing unit, the image memory, the storage unit, and the communication unit is connected to the I / O of the control unit 40. The control unit 40 exchanges information with each of the operation display unit, the image processing unit, the image memory, the storage unit, and the communication unit, thereby controlling each unit.

[0099] Next, a basic image forming process of the image forming apparatus according to this embodiment will be described.

[0100] In the image forming apparatus according to this embodiment, after image processing is performed on image data output from an image reading device (not shown) or a personal computer (PC) (not shown) by an image processing device (not shown), an image forming operation is performed by image forming units 1Y, 1M, 1C, and 1K.

[0101] In the image processing device, the input reflectivity data is subjected to image processing such as shading correction, position deviation correction, brightness / color space conversion, gamma correction, frame removal, color editing, motion editing and other image editing. The image data subjected to image processing is converted into color material grayscale data of four colors, Y, M, C, and K, and is output to the laser exposure device 13.

[0102] In the laser exposure device 13, exposure beam Bm emitted from a semiconductor laser, for example, is irradiated to each photosensitive body 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material grayscale data. In each photosensitive body 11 of the image forming units 1Y, 1M, 1C, and 1K, after the surface is charged by the charger 12, the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic image. The formed electrostatic image is developed into a toner image of each color of Y, M, C, and K by each image forming unit 1Y, 1M, 1C, and 1K.

[0103] The toner images formed on the photosensitive bodies 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 at the primary transfer section 10 where each photosensitive body 11 contacts the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (negative polarity) of the toner is applied to the substrate of the intermediate transfer belt 15 by the primary transfer roller 16, so that the toner images are sequentially overlapped on the surface of the intermediate transfer belt 15, thereby performing primary transfer.

[0104] After the toner images are sequentially transferred to the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner images are conveyed to the secondary transfer section 20. When the toner images are conveyed to the secondary transfer section 20, in the conveying unit, the paper feed roller 51 is rotated in accordance with the timing of conveying the toner images to the secondary transfer section 20, and paper K of a target size is supplied from the paper storage section 50. The paper K supplied by the paper feed roller 51 is conveyed by the conveying roller 52 and reaches the secondary transfer section 20 via the conveying guide 53. Before reaching the secondary transfer section 20, the paper K is temporarily stopped, and the registration roller (not shown) is rotated in accordance with the movement timing of the intermediate transfer belt 15 holding the toner images, so that the position of the paper K and the position of the toner images are aligned.

[0105] In the secondary transfer section 20, the secondary transfer roller 22 is pressed by the back roller 25 via the intermediate transfer belt 15. At this time, the paper K that is conveyed in time is sandwiched between the intermediate transfer belt 15 and the secondary transfer roller 22. At this time, if a voltage (secondary transfer bias) having the same polarity as the charging polarity (negative polarity) of the toner is applied from the power supply roller 26, a transfer electric field is formed between the secondary transfer roller 22 and the back roller 25. Then, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred onto the paper K in the secondary transfer section 20 pressed by the secondary transfer roller 22 and the back roller 25.

[0106] Thereafter, the paper K to which the toner image is electrostatically transferred is directly conveyed in a state of being peeled off from the intermediate transfer belt 15 by the secondary transfer roller 22, and is conveyed to the conveyor belt 55 provided on the downstream side of the secondary transfer roller 22 in the paper conveying direction. In the conveyor belt 55, the paper K is conveyed to the fixing device 60 at an optimum conveying speed in the fixing device 60. The unfixed toner image on the paper K conveyed to the fixing device 60 is subjected to a fixing process using heat and pressure by the fixing device 60, and is thereby fixed on the paper K. Then, the paper K on which the fixed image is formed is conveyed to a paper discharge accommodating portion (not shown) provided in a discharge portion of the image forming apparatus.

[0107] On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning section as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the cleaning back roller 34 and the intermediate transfer belt cleaner 35 .

[0108] [Fusing unit]

[0109] The fixing unit is a unit that fixes the toner image transferred to the surface of the recording medium onto the recording medium, and includes:

[0110] a fixing belt in contact with the toner image transferred to the surface of the recording medium;

[0111] a rotating body that contacts the outer peripheral surface of the fixing belt and is provided so as to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to transport the recording medium; and

[0112] a heating source that heats the contact area between the fixing belt and the rotating body,

[0113] There is no particular limitation as long as it is the above-mentioned fixing unit.

[0114] Hereinafter, the fixing unit will be described by way of example, but the fixing unit is not limited thereto.

[0115] -Fixing device according to the first embodiment: DH1 method-

[0116] The fixing unit may also be a fixing unit further comprising a pressure member, which is provided on the inner peripheral surface side of the fixing belt and pressurizes the fixing belt together with the rotating body in the contact area, and the heating source is a heating source that heats the contact area via the pressure member. That is, the fixing unit may also be a so-called direct heating type fixing unit.

[0117] Figure 2 This is a schematic structural diagram showing an example of the fixing device according to the first embodiment.

[0118] like Figure 2 As shown, the fixing device 60 involved in the first embodiment includes: a fixing belt 62, a pressure roller 64 (an example of a rotating body), a pressure pad 66 (an example of a pressure component), a halogen lamp 68 (an example of a heating source), a reflection plate 70 (an example of a reflection component), and a heat insulation component.

[0119] The outer peripheral surfaces of the fixing belt 62 and the pressure roller 64 are in contact with each other, forming a contact area N. Then, the fixing belt 62 and the pressure roller 64 rotate together, and the paper K is conveyed in the contact area N.

[0120] The reflection plate 70 reflects the radiant heat from the halogen lamp 68 toward the contact area N.

[0121] The heat insulating member 71 is provided between the side edge of the reflection plate 70 and the inner peripheral surface of the fixing belt 62 facing the side edge.

[0122] The fixing belt 62 is a belt that contacts the toner image transferred to the surface of the paper K. As an example, the fixing belt 62 may be an endless belt having an elastic layer (silicone rubber layer, etc.) and a release layer (fluororesin layer, etc.) sequentially formed on a base material (polyimide resin base material, etc.).

[0123] For example, from the viewpoint of reducing the heat capacity, the thickness of the fixing belt 62 is set to be 110 μm to 450 μm (preferably 110 μm to 430 μm).

[0124] The fixing belt 62 is rotatably supported by bearings (not shown) at both ends in the axial direction. In addition, a drive transmission component (gear, etc.) (not shown) is embedded in one end of the axial direction of the fixing belt 62. Then, the fixing belt 62 rotates as the drive transmission component rotates around the axis through a drive source (motor, etc.) (not shown).

[0125] The pressure roller 64 is provided so as to be in contact with the outer peripheral surface of the fixing belt 62 .

[0126] As an example, the pressure roller 64 is made of resin or metal and is formed into a cylindrical or columnar shape. A portion of the outer peripheral surface of the pressure roller 64 is pressed against the pressure pad 66 side via the fixing belt 62 via a bearing member and an elastic member (spring, etc.) not shown. Thus, the pressure roller 64 and the fixing belt 62 form a contact area N (so-called nip portion). That is, the pressure roller 64 has a function of sandwiching the fixing belt 62 (that is, the paper K and the toner image) with the pressure pad 66 in the contact area N to apply pressure.

[0127] Inserted components (caps, etc.) not shown are inserted into both ends of the pressure roller 64 in the axial direction, and the rigidity of the pressure roller 64 against radial external forces is improved. The inserted components can rotate around the axis through bearing components not shown. Then, the pressure roller 64 rotates with the rotation of the fixing belt 62. As a result, the pressure roller 64 rotates together with the fixing belt 62 in the contact area N to convey the paper K.

[0128] It should be noted that the fixing belt 62 may be configured to rotate as the pressure roller 64 is driven to rotate.

[0129] The pressure pad 66 is provided on the inner peripheral surface side of the fixing belt 62 .

[0130] As an example, the pressure pad 66 is formed of a columnar member made of resin or metal.

[0131] The pressure pad 66 has a function of pressing the pressure roller 64 to the pressure pad 66 side via the fixing belt 62 , thereby sandwiching and pressing the fixing belt 62 (that is, the paper K and the toner image) in the contact region N with the pressure roller 64 .

[0132] It should be noted that the pressure pad 66 may be pressed toward the pressure roller 64 side via the fixing belt 62 by an elastic member (spring, etc.). That is, the pressure pad 66 may be a member that is pressed from the pressure roller 64 to press the fixing belt 62, or a member that presses itself toward the pressure roller 64 to press the fixing belt 62.

[0133] Alternatively, a roller-shaped pressure member may be provided instead of the pressure pad 66 .

[0134] The halogen lamp 68 is provided on the inner peripheral surface of the fixing belt 62. Specifically, for example, the halogen lamp 68 is provided to face the contact region N via the pressure pad 66. And the halogen lamp 68 heats the contact region N directly.

[0135] The halogen lamp 68 is a cylindrical halogen lamp extending in the width direction (belt rotation axis direction) of the fixing belt 62. The halogen lamp 68 uses a filament with a small heat capacity as a heat source, and therefore starts radiating heat quickly after power is turned on.

[0136] It should be noted that a known heating source such as a ceramic heater or a Colts lamp may be provided instead of the halogen lamp 68 .

[0137] The reflection plate 70 is provided on the inner peripheral surface side of the fixing belt 62. Specifically, for example, the reflection plate 70 is provided to face the contact area N with the halogen lamp 68 interposed therebetween.

[0138] As an example, the reflector 70 is formed of a plate-shaped metal member or a plate-shaped resin member having a metal layer deposited on a reflective surface. The reflector 70 is curved so that the contact region N side is concave, for example.

[0139] The reflection plate 70 has a function of reflecting the radiant heat from the halogen lamp 68 toward the contact area N.

[0140] In the fixing device 60 according to the first embodiment, the toner image formed on the paper K is fixed to the paper K by applying pressure and heating to the toner image formed on the paper K in the contact region N between the fixing belt 62 and the pressure roller.

[0141] -Fixing device according to the second embodiment: DH2 method

[0142] The fixing unit may further include a pressing member for pressing the rotating body from the inner side of the fixing belt on the downstream side of the contact region. In this case, the rotating body preferably includes an elastic layer on a surface on the side pressing the fixing belt.

[0143] Figure 3 It is a schematic diagram showing the structure of a fixing device 80 according to the second embodiment.

[0144] The fixing device 80 includes a pressure roller 88 (an example of a first rotating body) and a fixing belt module 86 .

[0145] The fixing belt module 86 includes: a heating belt 84 (an example of a second rotating body), a pressing pad 87 (an example of a pressing member), a sliding member 82 (an example of a sliding member in this embodiment), and a halogen heater 89A (an example of a heat source) arranged near the pressing pad 87.

[0146] Furthermore, the fixing belt module 86 includes a support roller 90 , a support roller 92 , a posture correction roller 94 , and a support roller 98 .

[0147] The pressure roller 88 is arranged to be pressed against the heating belt 84 (fixing belt module 86 ), and a nip region N (nip portion) is formed in a region where the pressure roller 88 and the heating belt 84 (fixing belt module 86 ) are in contact with each other.

[0148] The heating belt 84 is configured in an endless shape and is rotatably supported by a pressing pad 87 and a support roller 90 disposed therein. The heating belt 84 is disposed so as to be pressed against the pressure roller 88 by the pressing pad 87 in the nip region N (nip portion).

[0149] The pressing pad 87 is wound with the heating belt 84 and presses the heating belt 84 against the pressure roller 88. The pressing pad 87 is configured so that the elastic layer 88B is elastically deformed. The pressing pad 87 is configured so that the elastic layer 88B is partially elastically deformed on the discharge side of the fixing device. The pressing pad 87 includes a front sandwiching member 87a and a peeling sandwiching member 87b, and is supported by a holding member 89.

[0150] The front nip member 87a is formed into a concave shape along the outer peripheral shape of the pressure roller 88, and is arranged on the entrance side of the nip region N to ensure the length of the nip region N (the distance in the sliding direction).

[0151] The peeling clamping member 87b is configured to be a protruding shape relative to the outer peripheral surface of the pressure roller 88, and is arranged on the exit side of the clamping area N. It causes local strain to the pressure roller 88 in the exit area of ​​the clamping area N, making it easier to peel the fixed recording medium from the pressure roller 88.

[0152] The pressing pad 87 includes a halogen heater 89A (an example of a heating source) in the vicinity thereof (for example, inside the holding member 89 ), and heats the heating belt 84 from the inner peripheral surface side.

[0153] For example, a lubricant supply device (not shown) that supplies lubricant (oil) to the inner peripheral surface of the heating belt 84 may be installed upstream of the front sandwiching member 87 a of the holding member 89 .

[0154] The sliding member 82 is formed in a sheet shape, and is disposed between the heating belt 84 and the pressing pad 87 so that its sliding surface (surface with dotted recesses) contacts the inner peripheral surface of the heating belt 84 .

[0155] The sliding member 82 participates in holding and supplying the lubricant (oil) between its sliding surface and the inner peripheral surface of the heating belt 84. The sliding member 82 is excellent in wear resistance, and the life of the fixing device 80 is prolonged.

[0156] The heating belt 84 is wound around the support roller 90 , and the heating belt 84 is supported at a position different from the pressing pad 87 .

[0157] The support roller 90 includes a halogen heater 90A (an example of a heat source) inside thereof, and heats the heating belt 84 from the inner peripheral surface side.

[0158] The support roller 90 is, for example, a cylindrical roller of aluminum, and a release layer made of fluororesin having a thickness of, for example, 20 μm is formed on the outer peripheral surface of the roller.

[0159] The support roller 92 is disposed so as to be in contact with the outer peripheral surface of the heating belt 84 between the pressing pad 87 and the support roller 90 , and defines a winding path of the heating belt 84 .

[0160] The support roller 92 has a halogen heater 92A (an example of a heat source) inside thereof, and heats the heating belt 84 from the outer peripheral surface side.

[0161] The support roller 92 is, for example, a cylindrical roller of aluminum, and a release layer made of fluororesin having a thickness of, for example, 20 μm is formed on the outer peripheral surface of the roller.

[0162] As for the halogen heater 89A, the halogen heater 90A, and the halogen heater 92A which are examples of the heating source, at least one of them may be provided.

[0163] The posture correction roller 94 is disposed so as to be in contact with the inner peripheral surface of the heating belt 84 between the support roller 90 and the pressing pad 87 , and corrects the posture of the heating belt 84 between the support roller 90 and the pressing pad 87 .

[0164] An end position measuring mechanism (not shown) for measuring the end position of the heating belt 84 is arranged near the posture correction roller 94, and an axial displacement mechanism (not shown) for displacing the axial contact position of the heating belt 84 according to the measurement result of the end position measuring mechanism is arranged on the posture correction roller 94. These mechanisms correct the posture of the heating belt 84.

[0165] The posture correction roller 94 is, for example, a cylindrical roller made of aluminum.

[0166] The support roller 98 is arranged to contact the inner peripheral surface of the heating belt 84 between the pressing pad 87 and the support roller 92 , and applies tension to the heating belt 84 from the inner peripheral surface of the heating belt 84 on the downstream side of the nip region N.

[0167] The support roller 98 is, for example, a cylindrical roller of aluminum, and a release layer made of, for example, a 20 μm-thick fluororesin is formed on the outer peripheral surface thereof.

[0168] The pressure roller 88 is disposed so as to be pressed against the heating belt 84 at a location where the heating belt 84 is wound around the pressing pad 87 .

[0169] The pressure roller 88 is rotatably provided, and as the heating belt 84 rotates in the direction of arrow E, the pressure roller 88 is driven by the heating belt 84 and rotates in the direction of arrow F.

[0170] The pressure roller 88 is formed by laminating an elastic layer 88B made of, for example, silicone rubber and a release layer (not shown) made of, for example, 100 μm thick fluororesin in this order on the outer peripheral surface of a cylindrical roller 88A made of aluminum.

[0171] For example, the support rollers 90 and 92 are rotated by a driving motor (not shown), and the heating belt 84 is driven by the rotation to rotate in the direction of arrow E. The pressure roller 88 is driven by the rotation of the heating belt 84 to rotate in the direction of arrow F.

[0172] The paper K (recording medium) having the unfixed toner image is transported to the nip region N of the fixing device 80. When the paper K passes through the nip region N, the toner image on the paper K is fixed by the pressure and heat acting on the nip region N.

[0173] -Fixing device according to the third embodiment: electromagnetic induction heating method-

[0174] The fixing unit may be an electromagnetic induction fixing unit. When the fixing unit is an electromagnetic induction fixing unit, the fixing unit includes an electromagnetic induction heating device, and preferably, a metal layer is provided inside the fixing belt as the heating source.

[0175] Figure 4 It is a schematic diagram showing an example of a fixing device according to a third embodiment.

[0176] The fixing device 200 according to the third embodiment is an electromagnetic induction type fixing device including a fixing unit having a composite substrate.

[0177] like Figure 4As shown, the pressure roller 211 (an example of the second rotating body) is configured to pressurize a portion of the heating belt 210 (an example of the first rotating body), and from the viewpoint of effectively performing fixing, a contact area (nip) is formed between the heating belt 210 and the pressure roller 211, and the heating belt 210 is bent into a shape along the circumferential surface of the pressure roller 211. In addition, from the viewpoint of ensuring the peelability of the recording medium, a curved portion where the belt is curved is formed at the end of the contact area (nip).

[0178] The pressure roller 211 is configured by forming an elastic layer 211B made of silicone rubber or the like on a base material 211A, and further forming a release layer 211C made of a fluorine-based compound on the elastic layer 211B.

[0179] An opposing member 213 is disposed inside the heating belt 210 at a position opposing the pressure roller 211. The opposing member 213 is made of metal, heat-resistant resin, heat-resistant rubber, etc., and includes a pad 213B that contacts the inner peripheral surface of the heating belt 210 to locally increase the pressure, and a support body 213A that supports the pad 213B.

[0180] The belt 210 is an endless belt having a layer structure in which a metal layer 220B, an adhesive layer 220C, an elastic layer 220D, and an anti-sticking layer 220E are sequentially stacked on the outer peripheral surface of a base material 220A. It should be noted that the metal layer 220B is sequentially stacked with a base metal layer 222, an electromagnetic induction metal layer 224 that self-heats by electromagnetic induction, and a metal protective layer 226.

[0181] The metal layer 220B is not particularly limited as long as it includes a nickel-plated layer. The metal layer 220B shows a structure in which a base metal layer 222, an electromagnetic induction metal layer 224, and a metal protection layer 226 are stacked in this order, but the number of stacked metal layers may be different.

[0182] The base material 220A may be a layer that has little change in physical properties and maintains high strength even when the metal layer 220B generates heat. Therefore, the base material 220A is preferably mainly composed of a heat-resistant resin.

[0183] The base metal layer 222 is a layer formed in advance in order to form the electromagnetic induction metal layer 224 on the outer peripheral surface of the base material 220A by electroplating or the like, and is provided as necessary.

[0184] The electromagnetic induction metal layer 224 is a heat generating layer having a function of generating heat by eddy current generated in the layer when a magnetic field is applied, and is made of a metal that generates electromagnetic induction action.

[0185] On the outer peripheral surface side of the electromagnetic induction metal layer 224 , a metal protection layer is preferably provided in contact with the electromagnetic induction metal layer 224 .

[0186] The adhesive layer 220C is a layer provided between the metal layer 220B and the elastic layer 220D.

[0187] The elastic layer 220D is provided from the viewpoint of providing elasticity to the fixing unit when pressed from the outer peripheral side, and is a layer that plays a role in causing the surface of the fixing unit to follow the unevenness of the toner image on the recording medium and to come into close contact with the toner image.

[0188] The anti-adhesive layer 220E is a layer that plays a role in preventing the toner image in a molten state from being adhered to the surface (peripheral surface) on the side in contact with the recording medium during fixing. The surface layer is provided as necessary.

[0189] An electromagnetic induction heating device 212 having an electromagnetic induction coil (an example of a heating layer) 212a built therein is provided at a position centered on the heating belt 210 and facing the pressure roller 211. The electromagnetic induction heating device 212 applies an alternating current to the electromagnetic induction coil, thereby changing the generated magnetic field by an excitation circuit, and causing an eddy current to be generated in the metal layer (electromagnetic induction metal layer 224) of the heating belt 210. The eddy current is converted into heat (Joule heat) by the resistance of the metal layer (not shown), resulting in the surface of the heating belt 210 being heated.

[0190] It should be noted that the position of the electromagnetic induction heating device 212 is not limited to Figure 4 The position shown may be, for example, provided on the upstream side in the rotation direction B with respect to the contact region of the heating belt 210 , or may be provided on the inner side of the heating belt 210 .

[0191] In the fixing device 200 involved in the third embodiment, the driving device transmits driving force to the gear fixed to the end of the heating belt 210, so that the heating belt 210 rotates in the direction of arrow B by itself, and the pressure roller 211 rotates in the opposite direction, that is, the direction of arrow C, as the heating belt 210 rotates.

[0192] The recording medium 215 on which the unfixed toner image 214 is formed passes through the contact area (nip) of the heating belt 210 and the pressure roller 211 in the fixing device 200 in the direction of arrow A, and the unfixed toner image 214 becomes molten and pressure is applied, thereby being fixed to the recording medium 215 .

[0193] -Fixing device according to fourth embodiment: Linear heating element method-

[0194] The fixing unit may be a fixing unit whose heating source is a linear heating element. The fixing unit whose heating source is a linear heating element preferably has a power supply unit for pulse-energizing the linear heating element. The fixing unit whose heating source is a linear heating element may also be a fixing unit that further has: a sliding member that slides with the linear heating element; a power supply unit that pulse-energizes the linear heating element; and a cooling member that cools the fixed image after the toner image transferred to the surface of the recording medium is fixed, and the fixing unit heats the contact area from the linear heating element through the sliding member.

[0195] Figure 5 1 is a schematic diagram showing an example of a fixing device according to the fourth embodiment. Components having substantially the same functions as those of the fixing device 60 according to the first embodiment are denoted by the same reference numerals, and their description is omitted.

[0196] like Figure 5 As shown, the fixing device 60 involved in the fourth embodiment includes: a fixing belt 62, a pressure roller 64 (an example of a rotating body), a paper conveyor belt 72, a linear heating element 74 (an example of a heating source and a pressure component), a pulse power supply unit 74A and a radiator 76 (an example of a cooling unit).

[0197] The outer peripheral surfaces of the fixing belt 62 and the pressure roller 64 are in contact with each other via the paper conveying belt 72 , forming a contact area N. Then, the fixing belt 62 and the pressure roller 64 rotate together, and the paper K is conveyed in the contact area.

[0198] It should be noted that the contact region N where the fixing belt 62 and the outer peripheral surface of the pressure roller 64 are in contact also includes a contact region N where the fixing belt 62 and the outer peripheral surface of the pressure roller 64 are in contact with each other via members such as the paper conveying belt 72 .

[0199] The fixing belt 62 is supported by the rotating support rollers 62A, 62B, and 62C. The first rotating support roller 62B located downstream of the linear heating element 74 in the rotation direction of the fixing belt 62 serves as a driving roller for rotating the fixing belt 62.

[0200] The pressure roller 64 is provided on the inner peripheral surface side of the paper conveying belt 72. A part of the outer peripheral surface of the pressure roller 64 is pressed against the linear heating element 74 side via a bearing member and an elastic member (spring, etc.) not shown in the figure, via the fixing belt 62 and the paper conveying belt 72. Thus, the pressure roller 64 and the fixing belt 62 form a contact area N (so-called nip portion) via the paper conveying belt 72. That is, the pressure roller 64 has a function of sandwiching the fixing belt 62 and the paper conveying belt 72 (i.e., the paper K and the toner image) together with the pressure pad 66 in the contact area N to apply pressure.

[0201] The paper conveying belt 72 is supported by the rotating support rollers 72A, 72B, and 72C while being given tension. The paper conveying belt 72 is driven to rotate as the fixing belt 62 rotates.

[0202] Here, the rotation support rollers 62A and 62B supporting the fixing belt 62 and the rotation support rollers 72A and 72B supporting the paper conveying belt 72 are arranged opposite to each other with the fixing belt 62 and the paper conveying belt 72 sandwiched therebetween. That is, the fixing belt 62 and the paper conveying belt 72 are arranged so that the outer peripheral surfaces of each other face each other between the rotation support rollers 62A and 72A and the rotation support rollers 62B and 72B.

[0203] The linear heating element 74 is provided on the inner peripheral surface side of the fixing belt 62. Specifically, the linear heating element 74 is provided so as to face the contact region N. And the linear heating element 74 heats the contact region N directly.

[0204] The heating linear element 74 also has the function of pressing the pressure roller 64 against the fixing belt 62 and the paper conveying belt 72 to sandwich and press the fixing belt 62 (ie, the paper K and the toner image) with the pressure roller 64 in the contact region N.

[0205] The linear heating element 74 is composed of a long strip-shaped member extending along the width direction (belt rotation axis direction) of the fixing belt 62. The linear heating element 74 is, for example, a heating source having a linear heating portion formed by arranging a plurality of heating resistors as heat sources in a row on a substrate. That is, the linear heating element 74 is a heating element different from a heating element composed of a nickel-chromium heat-resistant alloy wire. Examples of the linear heating element 74 include a thermal head and the like.

[0206] The pulse current supplying unit 74A is constituted by a power source, and is electrically connected to the linear heating element 74 in order to supply pulse current to the linear heating element 74. Specifically, the pulse current supplying unit 74A supplies pulse current to the heating resistor.

[0207] The shape of the energizing pulse applied by the pulse energizing unit 74A includes a rectangular wave, a triangular wave, a sine wave, etc. It should be noted that the energizing state between pulses does not need to be off.

[0208] The pulse current supplying unit 74A is connected to the control unit 40 . The pulse current supplying unit 74A is controlled by the control unit 40 to supply pulse current to the linear heating element 74 .

[0209] The heat sink 76 is provided so as to be in contact with the inner peripheral surface of the fixing belt 62. Specifically, for example, the heat sink 76 is provided on the downstream side of the contact region N in the rotation direction of the fixing belt 62.

[0210] The radiator 76 absorbs and dissipates the heat of the fixing belt 62 at a position downstream of the heated contact region N in the rotation direction of the fixing belt 62 to cool the fixing belt 62. Thus, the fixed image after the toner image is fixed in the contact region N is cooled.

[0211] In the fixing device 60 according to the fourth embodiment described above, the paper K on which the toner image is formed is pressurized and heated in the contact area N between the fixing belt 62 and the pressure roller via the paper conveying belt 72 , so that the toner image is fixed to the paper K. Thereafter, the fixed image on the paper K is cooled by the radiator 76 and then separated from the fixing belt 62 .

[0212] The linear heating element 74 can divide the heating area into a plurality of areas like a thermal head, for example, and thus the amount of heat generated can be easily controlled.

[0213] The fixed image fixed in the contact region N is cooled by the heat sink 76 (that is, after the melted toner constituting the image is solidified), and then detached from the fixing belt 62 .

[0214] It is also possible to not provide the heat sink 76 and to adopt the following method (see Figure 6 ): The rotating support roller 72B that supports the paper conveying belt 72 provided at the position where the fixed image is separated from the fixing belt 62 is enlarged in diameter, and the enlarged rotating support roller 72B is used as a cooling unit. If the rotating support roller 72B is enlarged in diameter (specifically, for example, if the rotating support roller 72B has a diameter larger than the rotating support roller 62B that supports the fixing belt 62), the fixed image can be cooled via the paper conveying belt 72 by the rotating support roller 72B.

[0215] [Electrostatic image developer]

[0216] The electrostatic image developer according to the present embodiment contains at least toner.

[0217] The electrostatic image developer according to the present embodiment may be a single-component developer containing only a toner, or may be a two-component developer containing a toner and a carrier.

[0218] [Toner]

[0219] The toner according to the present embodiment comprises toner particles and silica particles, wherein the silica has a number average particle size of 110 nm to 130 nm, a large diameter side number particle size distribution index (upper GSDp) of less than 1.080, an average circularity of 0.94 to 0.98, and a proportion of particles having a circularity of 0.92 or more of 80% by number. The toner according to the present embodiment is configured to further comprise inorganic oxide particles, lubricant particles, and external additives other than the inorganic oxide particles and the lubricant particles as required.

[0220] <Toner Particles>

[0221] The toner particles are configured to include, for example, a binder resin, a colorant as needed, a release agent, and other additives.

[0222] -Bonding resin-

[0223] Examples of the binder resin include vinyl resins composed of monomer polymers of styrenes (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers.

[0224] Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures thereof with the vinyl resins, or graft polymers obtained by polymerizing vinyl monomers in the presence of the non-vinyl resins.

[0225] These binder resins may be used alone or in combination of two or more.

[0226] (1) Styrene acrylic resin

[0227] As the binder resin, styrene acrylic resin is preferred.

[0228] Styrene acrylic resin is a copolymer obtained by copolymerizing at least a styrene monomer (a monomer having a styrene skeleton) and a (meth) acrylic monomer (a monomer having a (meth) acryloyl group, preferably a monomer having a (meth) acryloyloxy group). Styrene acrylic resin includes, for example, a copolymer of a styrene monomer and the (meth) acrylate monomer. It should be noted that the acrylic resin portion in the styrene acrylic resin is a partial structure obtained by polymerizing either or both of an acrylic monomer and a methacrylic monomer. In addition, "(meth) acrylic acid" is an expression including either "acrylic acid" or "methacrylic acid".

[0229] As the styrene monomer, for example, specifically, there can be mentioned: styrene, alkyl-substituted styrene (for example, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (for example, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, etc. The styrene monomer may be used alone or in combination of two or more.

[0230] Among these, as the styrene-based monomer, styrene is preferred from the viewpoints of easiness of reaction, easiness of reaction control, and availability.

[0231] Examples of the (meth)acrylic monomers include (meth)acrylic acid and (meth)acrylic acid esters. Examples of the (meth)acrylic acid esters include (meth)acrylic acid alkyl esters (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isopentyl (meth)acrylate, and n-octadecyl (meth)acrylate). (meth)acrylate, butyl ...

[0232] It should be noted that among the (meth)acrylic acid monomers, from the viewpoint of improving the fixing property of the toner, (meth)acrylic acid esters having an alkyl group with 2 to 14 carbon atoms (preferably 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms) are preferred. Among them, n-butyl (meth)acrylate is preferred, and n-butyl acrylate is particularly preferred.

[0233] The copolymerization ratio of the styrene-based monomer to the (meth)acrylic-based monomer (based on mass, styrene-based monomer / (meth)acrylic-based monomer) is not particularly limited, but is preferably 90 / 10 to 60 / 40.

[0234] The styrene acrylic resin preferably has a crosslinked structure. Preferred examples of the styrene acrylic resin having a crosslinked structure include styrene acrylic resins obtained by copolymerizing at least a styrene-based monomer, a (meth)acrylic-based monomer, and a crosslinkable monomer.

[0235] Examples of the crosslinkable monomer include bifunctional or higher-functional crosslinking agents.

[0236] Examples of the bifunctional crosslinking agent include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylenebis(meth)acrylamide, decanediol diacrylate, glycidyl(meth)acrylate, etc.), polyester di(meth)acrylate, and 2-([1'-methylpropyleneamino]carboxyamino)ethyl methacrylate.

[0237] Examples of the trifunctional or higher crosslinking agent include tri(meth)acrylate compounds (e.g., pentaerythritol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.), tetra(meth)acrylate compounds (e.g., pentaerythritol tetra(meth)acrylate, oligoester (meth)acrylate, etc.), 2,2-bis(4-methacryloyloxy, polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, and diallyl chlorendic acid.

[0238] Among them, as the crosslinking monomer, from the viewpoint of improving the fixing property of the toner, a (meth)acrylate compound having two or more functional groups is preferred, a difunctional (meth)acrylate compound is more preferred, a difunctional (meth)acrylate compound having an alkylene group having 6 to 20 carbon atoms is further preferred, and a difunctional (meth)acrylate compound having a linear alkylene group having 6 to 20 carbon atoms is particularly preferred.

[0239] The copolymerization ratio of the cross-linkable monomer to all monomers (based on mass, cross-linkable monomer / all monomers) is not particularly limited, but is preferably 2 / 1000 to 20 / 1000.

[0240] The glass transition temperature (Tg) of the styrene acrylic resin is preferably 40° C. or higher and 75° C. or lower, and more preferably 50° C. or higher and 65° C. or lower, from the viewpoint of improving the fixing property of the toner.

[0241] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, by “extrapolating the glass transition start temperature” described in the method for determining the glass transition temperature in JIS K 7121-1987 “Methods for determining transition temperatures of plastics”.

[0242] From the viewpoint of storage stability of the toner, the weight average molecular weight of the styrene acrylic resin is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and particularly preferably 20,000 to 80,000.

[0243] The method for preparing the styrene acrylic resin is not particularly limited, and various polymerization methods (e.g., solution polymerization, precipitation polymerization, suspension polymerization, block polymerization, emulsion polymerization, etc.) can be applied. In addition, the polymerization reaction can be applied to known operations (e.g., batch, semi-continuous, continuous, etc.).

[0244] (2) Polyester resin

[0245] As the binder resin, polyester resin is suitable.

[0246] As the polyester resin, for example, a known amorphous polyester resin can be cited. The polyester resin can also be used together with a crystalline polyester resin. However, as for the crystalline polyester resin, it can be used as long as the content is within the range of 2 mass % to 40 mass % (preferably 2 mass % to 20 mass %) relative to the total binder resin.

[0247] It should be noted that the "crystallinity" of a resin means that in differential scanning calorimetry (DSC), it does not mean a step-like change in endothermic value, but rather has a clear endothermic peak; specifically, it means that the half-width of the endothermic peak is within 10°C when measured at a heating rate of 10 (°C / min).

[0248] On the other hand, "non-crystalline" of a resin means when the half-peak width exceeds 10°C, when a step-like change in endothermic value is shown, or when no clear endothermic peak is observed.

[0249] Amorphous polyester resin

[0250] Examples of the non-crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the non-crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.

[0251] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaric acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexane dicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., carbon number of 1 to 5) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as the polycarboxylic acid.

[0252] The polycarboxylic acid can be used together with the dicarboxylic acid to form a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., carbon number of 1 to 5) alkyl esters.

[0253] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0254] Examples of the polyol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among them, the polyol is preferably an aromatic diol or an alicyclic diol, and more preferably an aromatic diol.

[0255] As the polyol, a trivalent or higher polyol that forms a cross-linked structure or a branched structure may be used together with a diol. Examples of the trivalent or higher polyol include glycerin, trimethylolpropane, and pentaerythritol.

[0256] The polyols may be used alone or in combination of two or more.

[0257] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C to 80°C, and more preferably 50°C to 65°C.

[0258] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by “extrapolating the glass transition start temperature” described in the method for determining the glass transition temperature in JIS K 7121-1987 “Methods for determining transition temperatures of plastics”.

[0259] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000.

[0260] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less.

[0261] The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0262] It should be noted that the weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight determination using GPC is performed in a THF solvent using a GPC HLC-8120GPC manufactured by Tosoh as a measuring device and a column TSKgel SuperHM-M (15 cm) manufactured by Tosoh. The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from the measurement results and a monodisperse polystyrene standard sample.

[0263] The amorphous polyester resin is obtained by a known production method, specifically, for example, by setting the polymerization temperature to 180° C. to 230° C., reducing the pressure in the reaction system as necessary, and reacting while removing water and alcohol generated during condensation.

[0264] It should be noted that when the monomer of the raw material is soluble or incompatible at the reaction temperature, a high boiling point solvent can be added as a dissolving aid to dissolve it. At this time, the polycondensation reaction is carried out while the dissolving aid is distilled off. In the case of the presence of a monomer with poor compatibility, the monomer with poor compatibility and the acid or alcohol expected to be polycondensed with the monomer are condensed in advance and then polycondensed together with the main component.

[0265] Crystalline polyester resin

[0266] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.

[0267] Here, since the crystalline polyester resin easily forms a crystal structure, it is preferable to use a polycondensate of a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group.

[0268] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower (e.g., having 1 to 5 carbon atoms) alkyl esters.

[0269] The polycarboxylic acid can be used together with the dicarboxylic acid to form a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., carbon number of 1 to 5) alkyl esters.

[0270] As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.

[0271] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0272] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion having carbon atoms of 7 or more and 20 or less). Examples of the aliphatic diols include ethylene 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, and 1,14-eicosandiol. Among these, preferred aliphatic diols are 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0273] The polyol may be a trivalent or higher alcohol that forms a cross-linked structure or a branched structure together with the diol. Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0274] The polyols may be used alone or in combination of two or more.

[0275] Here, the content of the aliphatic diol in the polyol is preferably 80 mol % or more, and preferably 90 mol % or more.

[0276] The melting temperature of the crystalline polyester resin is preferably 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C.

[0277] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Methods for determining transition temperatures of plastics”.

[0278] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0279] Similar to the amorphous polyester, the crystalline polyester resin can be obtained by, for example, a known production method.

[0280] The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and further preferably 60% by mass to 85% by mass, based on the entire toner particles.

[0281] -Colorants-

[0282] Examples of the coloring agent include carbon black, chrome yellow, Hansa yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Vulcan orange, watchung red, and the like. The present invention relates to various pigments including cyanine red, permanent red, brilliant magenta 3B, brilliant magenta 6B, Dupont oil red, pyrazolone red, litho red, rhodamine B lake, lake red C, pigment red, rose red, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green and malachite green oxalate; or various dyes including acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindigo, dioxazine, thiazine, azomethine, indigo, phthalocyanine, nigrosine, polymethine, triphenylmethane, diphenylmethane and thiazole.

[0283] The coloring agent may be used alone or in combination of two or more.

[0284] The colorant may be a surface-treated colorant or may be used in combination with a dispersant as required. In addition, multiple colorants may be used in combination.

[0285] The content of the colorant is, for example, preferably from 1 mass % to 30 mass % both inclusive, and more preferably from 3 mass % to 15 mass % both inclusive, based on the entire toner particles.

[0286] - Anti-sticking agent -

[0287] Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited thereto.

[0288] - Anti-sticking agent -

[0289] Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited thereto.

[0290] The melting temperature of the release agent is preferably 50°C to 110°C, more preferably 60°C to 100°C.

[0291] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Methods for determining transition temperatures of plastics”.

[0292] The content of the release agent is, for example, preferably from 1 mass % to 20 mass % both inclusive, and more preferably from 5 mass % to 15 mass % both inclusive, based on the entire toner particles.

[0293] -Other additives

[0294] Examples of other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in toner particles as internal additives.

[0295] -Characteristics of toner particles, etc.-

[0296] The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core (core particle) and a coating layer (shell layer) that covers the core.

[0297] Here, the toner particles of the core-shell structure may be composed of, for example, a core portion including a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer including a binder resin.

[0298] The volume average particle diameter (D50v) of the toner particles is preferably from 2 μm to 10 μm, and more preferably from 4 μm to 8 μm.

[0299] In addition, various average particle diameters and various particle size distribution indices of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman Coulter) and the electrolyte is measured using ISOTON-II (manufactured by Beckman Coulter).

[0300] In the measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and the solution is added to 100 ml to 150 ml of the electrolyte.

[0301] The electrolyte solution in which the sample was suspended was dispersed with an ultrasonic disperser for 1 minute, and the particle size distribution of particles with a particle size ranging from 2 μm to 60 μm was measured using a Coulter Multisizer II with an aperture of 100 μm. The number of particles sampled was 50,000.

[0302] For the particle size range (segment) divided based on the measured particle size distribution, the cumulative distribution of volume and the cumulative distribution of number are plotted from the smaller diameter side, respectively, the particle size accumulated to 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size accumulated to 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size accumulated to 84% is defined as the volume particle size D84v and the number particle size D84p.

[0303] Using them, the volume particle size distribution index (GSDv) is given as (D84v / D16v) 1 / 2 The number particle size distribution index (GSDp) is calculated as (D84p / D16p) 1 / 2 Calculated.

[0304] The average circularity of the toner particles is preferably from 0.94 to 1.00, and more preferably from 0.95 to 0.98.

[0305] The average circularity of the toner particles is calculated by (circle equivalent circumference) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value measured by the following method.

[0306] The average circularity was obtained by using a flow particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation), wherein the toner particles to be measured are first sucked and collected to form a flat flow, and a flash lamp is momentarily used to read the particle image as a still image, and the particle image is analyzed. The number of samples for obtaining the average circularity was 3500.

[0307] When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant, and then subjected to ultrasonic treatment to obtain toner particles from which the external additive has been removed.

[0308] <First Silica Particles>

[0309] The toner involved in this embodiment contains the following silica particles (hereinafter also referred to as "first silica particles"), wherein the number average particle size of the silica particles is greater than 110 nm and less than 130 nm, the number particle size distribution index on the large diameter side (upper side GSDp) is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of particles with a roundness of greater than 0.92 is greater than 80%.

[0310] The specific image forming apparatus according to the present embodiment can suppress the occurrence of variations in low-temperature fixing properties by accommodating a toner containing first silica particles as an external additive.

[0311] The number average particle size of the first silica particles is 110 nm to 130 nm, preferably 113 nm to 127 nm, and more preferably 115 nm to 125 nm, from the viewpoint of further suppressing the occurrence of variation in low-temperature fixing properties.

[0312] The method for making the number average particle size of the first silica particles within the above range is not particularly limited, and examples thereof include: making the first silica particles sol-gel silica particles, and in the manufacture of the sol-gel silica particles, adjusting the temperature or reaction time when mixing the base catalyst and tetraalkoxysilane; adjusting the concentrations of the base catalyst and tetraalkoxysilane; and the like.

[0313] The large-diameter side number size distribution index (upper GSDp) of the first silica particles is less than 1.080, and is preferably 1.077 or less, and more preferably less than 1.075, from the viewpoint of further suppressing the occurrence of variation in low-temperature fixing property.

[0314] From the viewpoint of further suppressing the occurrence of variations in low-temperature fixing properties, the smaller-diameter side number size distribution index (lower GSDp) of the first silica particles is preferably less than 1.080, more preferably 1.075 or less.

[0315] The method for making the upper GSDp and the lower GSDp in the first silica particle within the above-mentioned range is not particularly limited, and examples thereof include: making the first silica particle a sol-gel silica particle, and in the manufacture of the sol-gel silica particle, adjusting the temperature or reaction time when mixing the base catalyst and the tetraalkoxysilane; adjusting the concentrations of the base catalyst and the tetraalkoxysilane; and the like.

[0316] The number average particle size, the upper GSDp, and the lower GSDp of the first silica particles were determined as follows.

[0317] (1) The toner is dispersed in methanol, stirred at room temperature (23° C.), and then treated in an ultrasonic bath to separate the external additive from the toner. Next, the toner particles are precipitated by centrifugal separation, and the dispersion in which the external additive is dispersed is recovered. Thereafter, the methanol is distilled off to remove the external additive.

[0318] (2) The external additive is dispersed in resin particles (polyester, weight average molecular weight Mw=50,000) having a volume average particle diameter of 100 μm.

[0319] (3) An energy dispersive X-ray analyzer (EDX device) (EMAX Evolution X-Max 80 mm, manufactured by Horiba, Ltd.) was used. 2The resin particles dispersed with the external additive were observed using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies, S-4800) and images were taken at a magnification of 40,000 times. At this time, based on the presence of Si, more than 300 primary particles of silica were identified in one field of view by EDX analysis. For SEM, observation was performed under the conditions of an acceleration voltage of 15 kV, an emission current of 20 μA, and a WD of 15 mm; in EDX analysis, the detection time was set to 60 minutes under the same conditions.

[0320] (4) The obtained image was read into an image analyzer (LUZEXIII, manufactured by Nireco Corporation), and the area of ​​each particle was determined by image analysis.

[0321] (5) Based on the measured area value, the particle size of silica is calculated as a circle equivalent diameter.

[0322] (6) Select 100 silica particles with a circle equivalent diameter of 80 nm or more.

[0323] For the selected silica particles, a cumulative distribution of circle-equivalent diameters is plotted from the smaller diameter side, and the particle diameter at which the cumulative distribution reaches 50% is defined as the number average particle diameter of the first silica particles.

[0324] For the selected silica particles, the cumulative distribution of the equivalent circle diameter is drawn from the small diameter side, and the particle size accumulated to 16% is defined as the number particle size D16p, the particle size accumulated to 50% is defined as the number average particle size D50p, and the particle size accumulated to 84% is defined as the number particle size D84p. In addition, the number particle size distribution index on the large diameter side (upper side GSDp) is (D84p / D50p) 1 / 2 The particle size distribution index on the smaller diameter side (lower GSDp) is calculated as (D50p / D16p) 1 / 2 And calculate.

[0325] The average circularity of the first silica particles is 0.94 to 0.98, and is preferably 0.945 to 0.975, and more preferably 0.950 to 0.970, from the viewpoint of further suppressing the occurrence of variation in low-temperature fixing property.

[0326] The method for making the average roundness of the first silica particles within the above range is not particularly limited, and examples thereof include: making the first silica particles sol-gel silica particles, and in the manufacture of the sol-gel silica particles, adjusting the reaction time when mixing the base catalyst and tetraalkoxysilane; adjusting the concentration of the base catalyst; and the like.

[0327] The proportion of silica particles having a circularity of 0.92 or more in the first silica particles is 80% by number or more, preferably 85% by number or more, and more preferably 87% by number or more from the viewpoint of further suppressing the occurrence of variations in low-temperature fixing properties.

[0328] The method for making the proportion of silica particles having a roundness of 0.92 or more in the first silica particles fall within the above range is not particularly limited, and examples thereof include: making the first silica particles sol-gel silica particles, and adjusting the temperature when mixing the alkaline catalyst and tetraalkoxysilane during the manufacture of the sol-gel silica particles; and the like.

[0329] The average circularity of the first silica particles and the ratio of silica particles having a circularity of 0.92 or more in the first silica particles were determined as follows.

[0330] The circularity of the 100 particles selected in the method for determining the number average particle size of the first silica particles is calculated by the following formula (1). The 50% circularity accumulated from the smaller diameter side of the obtained circularity is taken as the average circularity of the first silica particles.

[0331] Formula (1): roundness = 4π × (A / I 2 )

[0332] In the formula (1), I represents the perimeter of the primary particle on the image, and A represents the projected area of ​​the primary particle.

[0333] When the average circularity is determined, the ratio of the number of particles having a circularity of 0.92 or more to 100 particles of each circularity is taken as the number ratio of silica particles having a circularity of 0.92 or more in the first silica particles.

[0334] From the viewpoint of further suppressing the occurrence of variations in low-temperature fixing properties, the hydrophobization degree of the first silica particles is preferably 50% to 80%, more preferably 50% to 75%, and even more preferably 50% to 70%.

[0335] The method for making the hydrophobization degree of the first silica particles within the above range is not particularly limited, and examples thereof include: making the first silica particles sol-gel silica particles, and in the manufacture of the sol-gel silica particles, using a hydrophobization treatment agent to hydrophobize the surface of the silica particles in the presence of supercritical carbon dioxide; and the like.

[0336] The hydrophobization degree of the first silica particles is determined as follows.

[0337] 0.2 mass % of silica particles as a sample were added to 50 ml of ion exchange water, and methanol was dripped from a burette while stirring with a magnetic stirrer. At this time, the methanol mass fraction (%) in the methanol-ion exchange water mixed solution at the end point when the total amount of the sample sank into the solution (= methanol addition amount / (methanol addition amount + ion exchange water amount)) was calculated as the hydrophobicity (%).

[0338] The first silica particles are made of silicon dioxide, i.e., SiO 2 The first silica particles may be particles of a main component, which may be either crystalline or amorphous. The first silica particles may be particles made from silicon compounds such as water glass and alkoxysilane, or may be particles obtained by crushing quartz. Examples of the first silica particles include: sol-gel silica particles; aqueous colloidal silica particles; alcoholic silica particles; fumed silica particles obtained by a gas phase method, etc.; fused silica particles; and the like. Among the above, the first silica particles preferably include sol-gel silica particles.

[0339] Sol-gel silica particles are obtained, for example, as follows. Tetraalkoxysilane (TMOS, etc.) is added dropwise to an alkaline catalyst solution containing an alcohol compound and ammonia water to hydrolyze and condense the tetraalkoxysilane to obtain a suspension containing sol-gel silica particles. Then, the solvent is removed from the suspension to obtain granules. Then, the sol-gel silica particles are obtained by drying the granules.

[0340] The first silica particles may be silica particles subjected to a hydrophobic treatment using a hydrophobic treatment agent.

[0341] As a hydrophobic treatment agent, for example, a known organosilicon compound with an alkyl group (such as a methyl group, an ethyl group, a propyl group, a butyl group, etc.) can be cited, and specific examples include alkoxysilane compounds, siloxane compounds, silazane compounds, etc. Among the above, the hydrophobic treatment agent preferably includes at least one of a siloxane compound and a silazane compound. The hydrophobic treatment agent can be used alone or in combination with two or more.

[0342] Examples of the siloxane compound include silicone oil and silicone resin. The silicone oil preferably includes dimethyl silicone oil. The siloxane compound may be used alone or in combination of two or more.

[0343] Examples of the silazane compound include hexamethyldisilazane and tetramethyldisilazane. Of the above, the silazane compound preferably includes hexamethyldisilazane (HMDS). The silazane compound may be used alone or in combination of two or more.

[0344] From the viewpoint of increasing the hydrophobization degree of the first silica particles, the surface adhesion amount of the hydrophobizing agent such as the silazane compound attached to the surface of the first silica particles is preferably 0.01 mass % to 5 mass % relative to the first silica particles, more preferably 0.05 mass % to 3 mass %, and even more preferably 0.10 mass % to 2 mass %.

[0345] As a method for hydrophobizing the first silica particles using a hydrophobizing agent, for example, there can be cited: a method of dissolving the hydrophobizing agent in supercritical carbon dioxide using supercritical carbon dioxide, thereby causing the hydrophobizing agent to adhere to the surface of the silica particles; a method of applying (e.g., spraying, coating) a solution containing a hydrophobizing agent and a solvent that dissolves the hydrophobizing agent to the surface of the silica particles in the atmosphere, thereby causing the hydrophobizing agent to adhere to the surface of the silica particles; a method of adding a solution containing a hydrophobizing agent and a solvent that dissolves the hydrophobizing agent to a silica particle dispersion in the atmosphere, maintaining the solution, and then drying the mixed solution of the silica particle dispersion and the solution.

[0346] <Other additives>

[0347] The toner according to the present embodiment may further include other external additives (hereinafter also referred to as "other external additives") other than the first silica particles. Examples of other external additives include inorganic oxide particles. Examples of inorganic oxide particles include SiO 2 、TiO 2 、Al 2 O 3 , CuO, ZnO, SnO 2 、CeO 2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O、Na 2 O, ZrO 2 、CaO·SiO 2 , K 2 O·(TiO 2 ) n 、Al 2 O 3 ·2SiO 2 、CaCO 3 MgCO 3 ,BaSO 4 MgSO 4 Among the above, the inorganic oxide particles preferably include TiO 2 、SiO 2, that is, titanium oxide particles or silicon dioxide particles (hereinafter also referred to as "second silicon dioxide particles"). ).

[0348] From the viewpoint of further suppressing the occurrence of variations in low-temperature fixing properties, the number average particle size of the inorganic oxide particles is preferably from 5 nm to 50 nm, and more preferably from 10 nm to 40 nm.

[0349] The number average particle size of the inorganic oxide particles is determined as follows.

[0350] (1) The toner is dispersed in methanol, stirred at room temperature (23° C.), and then treated in an ultrasonic bath to separate the external additive from the toner. Next, the toner particles are precipitated by centrifugal separation, and the dispersion in which the external additive is dispersed is recovered. Thereafter, the methanol is distilled off to remove the external additive.

[0351] (2) The external additive is dispersed in resin particles (polyester, weight average molecular weight Mw=50,000) having a volume average particle diameter of 100 μm.

[0352] (3) An energy dispersive X-ray analyzer (EDX device) (EMAX Evolution X-Max 80 mm, manufactured by Horiba, Ltd.) was used. 2 The resin particles dispersed with the external additive were observed using a scanning electron microscope (SEM) (manufactured by Hitachi High-Technologies, S-4800) and an image was taken at a magnification of 40,000 times. At this time, EDX analysis was performed to identify 300 or more primary particles of the inorganic oxide particles in one field of view based on the presence of atoms (Si, Ti, etc.) contained in each inorganic oxide particle. For SEM, observation was performed under the conditions of an acceleration voltage of 15 kV, an emission current of 20 μA, and a WD of 15 mm; in EDX analysis, the detection time was set to 60 minutes under the same conditions.

[0353] (4) The obtained image was read into an image analyzer (LUZEXIII, manufactured by Nireco Corporation), and the area of ​​each particle was determined by image analysis.

[0354] (5) Based on the measured area value, the particle size of each inorganic oxide particle is determined as a circle equivalent diameter.

[0355] (6) 100 particles with a circle equivalent diameter of less than 80 nm were screened. For the selected particles, the cumulative distribution of the circle equivalent diameter was plotted from the smaller diameter side, and the particle diameter at which the cumulative distribution reached 50% was taken as the number average particle diameter of the inorganic oxide particles.

[0356] The surface of the inorganic oxide particles as an external additive can be subjected to hydrophobic treatment. The hydrophobic treatment is carried out, for example, by impregnating the inorganic oxide particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, etc. These can be used alone or in combination of two or more.

[0357] The amount of the hydrophobizing agent is usually 1 part by mass or more and 10 parts by mass or less, for example, relative to 100 parts by mass of the inorganic oxide particles.

[0358] Examples of the external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), detergent active agents (for example, particles of fluorine-based polymers), and the like.

[0359] The amount of the other external additives is, for example, preferably from 0.01% by mass to 5% by mass, and more preferably from 0.01% by mass to 2.0% by mass, based on the toner particles.

[0360] <Lubricant particles>

[0361] When lubricant is supplied from the developer (toner thereof) contained in the developing device 18 to the photoreceptor 11, that is, when the developing device 18 also serves as a lubricant supplying member, the toner also contains granular lubricant as an external additive (hereinafter referred to as "lubricant particles").

[0362] As a preferred embodiment of the lubricant particles, particles of the same lubricant as those exemplified in the lubricant 66A in the lubricant supplying member can be cited as a preferred embodiment.

[0363] The volume average particle size of the lubricant particles is preferably 0.8 to 1.2 times that of the toner particles. Specifically, the volume average particle size of the lubricant particles is preferably 0.3 to 8 μm, more preferably 0.5 to 5.0 μm.

[0364] The volume average particle size of the lubricant particles is a value obtained by measuring the following method. First, the toner to be measured is observed by a scanning electron microscope (SEM). Then, the equivalent circular diameter of each of 100 lubricant particles to be measured is determined by image analysis, and the equivalent circular diameter of 50% (the 50th) of the number of particles from the small diameter side in the volume-based distribution is taken as the volume average particle size. In the image analysis to determine the equivalent circular diameter of 100 lubricant particles to be measured, an analysis device (ERA-8900: manufactured by Elionix) is used to capture a two-dimensional image with a magnification of 10,000 times, and the image analysis software WinROOF (manufactured by Mitani Shoji Co., Ltd.) is used to determine the projected area under the condition of 0.010000μm / pixel, and the equivalent circular diameter is calculated using the formula: equivalent circular diameter = 2√(projected area / π).

[0365] The content (external addition amount) of the lubricant particles is preferably 0.02 to 5 parts by mass, more preferably 0.05 to 3.0 parts by mass, and further preferably 0.08 to 1.0 parts by mass, based on 100 parts by mass of the toner particles.

[0366] <Method for producing toner>

[0367] Next, a method for producing a toner according to the present embodiment will be described.

[0368] The toner according to the present embodiment is obtained by manufacturing toner particles and then adding an external additive to the outside of the toner particles.

[0369] The toner particles can be produced by any of dry methods (such as kneading and pulverization methods) and wet methods (such as aggregation, suspension polymerization, and dissolution suspension methods). The method for producing the toner particles is not particularly limited to these methods, and a known method can be used.

[0370] Furthermore, the toner in the present embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. The mixing can be performed, for example, by a V-type mixer, a Henschel mixer, a Loedige mixer, etc. Furthermore, as required, a vibration sieving machine, a wind sieving machine, etc. can also be used to remove coarse particles of the toner.

[0371] [Carrier]

[0372] The carrier is not particularly limited, and known carriers can be cited. Examples of the carrier include: a coated carrier in which a coating resin is coated on the surface of a core material composed of magnetic powder; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin; and a resin impregnation type carrier in which porous magnetic powder is impregnated with a resin.

[0373] Note that the magnetic powder dispersed carrier and the resin impregnated carrier may be a carrier in which the constituent particles of the carrier serve as a core material and the core material is coated with a coating resin.

[0374] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0375] Examples of the coating resin and the base resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylate copolymer, straight-chain silicone resin containing an organic siloxane bond or a modified product thereof; fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, etc. It should be noted that the coating resin and the base resin may also contain other additives such as conductive particles.

[0376] Examples of the conductive particles include particles of metals such as gold, silver, and copper; and particles of carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0377] In order to coat the surface of the core material with a coating resin, a coating method using a coating layer forming solution can be cited, wherein the coating layer forming solution is obtained by dissolving the coating resin and various additives as required in an appropriate solvent. The solvent is not particularly limited, and can be selected by considering the coating resin used, coating adaptability, etc. Specific resin coating methods include: an immersion method in which the core material is immersed in a coating layer forming solution; a spray method in which the coating layer forming solution is sprayed on the surface of the core material in a mist form; a fluidized bed method in which the coating layer forming solution is sprayed in a mist form while the core material is floated by flowing air; a kneader-coater method in which the core material of the carrier and the coating layer forming solution are mixed in a kneader-coater and the solvent is removed, etc.

[0378] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0379] Example

[0380] Hereinafter, examples of the present application will be described, but the present invention is not limited to the following examples. It should be noted that in the following description, "parts" and "%" are based on mass unless otherwise specified.

[0381] - Preparation of the first silica particles -

[0382] (Preparation of Silica Particle Dispersion Liquid (1))

[0383] 300 parts of methanol and 70 parts of 10% ammonia water were added to a glass reaction container equipped with a stirrer, a dropping nozzle, and a thermometer, and mixed to obtain an alkali catalyst solution. After adjusting the alkali catalyst solution to 30°C (dropping start temperature), 185 parts of tetramethoxysilane and 50 parts of 8% ammonia water were added dropwise while stirring to obtain a hydrophilic silica particle dispersion (solid content 12%). Here, the dropping time is 30 minutes. Then, the obtained silica particle dispersion is concentrated to a solid content of 40% by a rotary filter R-Fine (manufactured by Kotobuki Industry Co., Ltd.). The concentrated substance is used as silica particle dispersion (1).

[0384] (Preparation of Silica Particle Dispersions (2) to (8) and (c1) to (c6))

[0385] In the preparation of the silica particle dispersion (1), silica particle dispersions (2) to (8) and (c1) to (c6) were prepared in the same manner as the silica particle dispersion (1), except that the conditions of the alkaline catalyst solution (the amount of methanol, the concentration and amount of ammonia water) and the conditions for forming silica particles (the amount of tetramethoxysilane (TMOS) in the alkaline catalyst solution, the concentration and total amount of ammonia water added, the time for adding TMOS and ammonia water, and the temperature at which the addition started) were changed according to Table 1.

[0386] (Preparation of Surface-treated Silica Particles (S1))

[0387] The silica particles were surface treated with a siloxane compound in a supercritical carbon dioxide atmosphere using the silica particle dispersion (1) as shown below. The surface treatment used an apparatus equipped with a carbon dioxide bottle, a carbon dioxide pump, an entrainer pump, an autoclave (capacity 500 ml) with a stirrer, and a pressure valve.

[0388] First, 300 parts of silica particle dispersion (1) were added to an autoclave (capacity 500 ml) with a stirrer, and the stirrer was rotated at 100 rpm. Then, liquefied carbon dioxide was injected into the autoclave, and the temperature was raised by a heater while the pressure was raised by a carbon dioxide pump, so that the autoclave was in a supercritical state of 150°C and 15 MPa. While maintaining the pressure in the autoclave at 15 MPa by a pressure valve, supercritical carbon dioxide was circulated by a carbon dioxide pump to remove methanol and water from the silica particle dispersion (1) (solvent removal process), and silica particles (untreated silica particles) were obtained.

[0389] Next, when the amount of supercritical carbon dioxide flowing (accumulated amount: measured as the amount of carbon dioxide flowing in a standard state) reached 900 parts, the flow of supercritical carbon dioxide was stopped.

[0390] Then, the temperature of 150°C is maintained by a heater, the pressure of 15MPa is maintained by a carbon dioxide pump, and the supercritical state of carbon dioxide is maintained in the autoclave. After the treatment agent solution is injected into the autoclave by an entrainer pump, it is stirred and reacted at 180°C for 20 minutes. The treatment agent solution is obtained by dissolving 0.3 parts of dimethyl silicone oil (DSO: trade name "KF-96 (Shin-Etsu Chemical Co., Ltd.)") having a viscosity of 10000cSt as a siloxane compound in 20 parts of hexamethyldisilazane (HMDS: Organic Synthetic Pharmaceuticals Co., Ltd.) as a hydrophobic treatment agent. Then, supercritical carbon dioxide is circulated again to remove the remaining treatment agent solution. Afterwards, stirring is stopped, the pressure valve is opened, the pressure in the autoclave is released to atmospheric pressure, and the temperature is reduced to room temperature (25°C).

[0391] In this manner, the solvent removal step and the surface treatment with HMDS and DSO were sequentially performed to obtain surface-treated silica particles (S1).

[0392] (Preparation of Surface-treated Silica Particles (S2) to (S8) and (cS1) to (cS6))

[0393] Surface-treated silica particles (S2) to (S8) and (cS1) to (cS6) were obtained in the same manner as in the preparation of the surface-treated silica particles (S1).

[0394] (Preparation of Surface-treated Silica Particles (cS7) to (cS8))

[0395] Surface-treated silica particles (cS7) were obtained in the same manner as in paragraphs 0051 to 0053 of JP-A-2008-174430. Surface-treated silica particles (cS8) were obtained in the same manner as in paragraph 0019 of JP-A-2001-194824.

[0396] [Table 1]

[0397]

[0398] -Preparation of Polyester Resin Particle Dispersion-

[0399] (Preparation of Amorphous Polyester Resin Particle Dispersion (A1))

[0400] Terephthalic acid: 70 parts

[0401] Fumaric acid: 30 parts

[0402] Ethylene glycol: 45 parts

[0403] 1,5-Pentanediol: 46 parts

[0404] The above materials were added to a flask equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor and a distillation tower, and the temperature was raised to 220°C in 1 hour under a nitrogen flow. 1 part of tetraethoxytitanium was added to 100 parts of the total of the above materials. While distilling off the generated water, the temperature was raised to 240°C in 0.5 hours, and the dehydration condensation reaction was continued at this temperature for 1 hour, and then the reactant was cooled. In this way, a polyester resin with a weight average molecular weight of 9500 and a glass transition temperature of 62°C was synthesized.

[0405] 40 parts of ethyl acetate and 25 parts of 2-butanol were placed in a container equipped with a temperature control unit and a nitrogen replacement unit to prepare a mixed solvent, and then 100 parts of polyester resin were slowly added and dissolved, and a 10% aqueous ammonia solution (equivalent to 3 times the amount of the acid value of the resin in terms of molar ratio) was added thereto, and stirred for 30 minutes. Next, the container was replaced with dry nitrogen, and the temperature was maintained at 40°C. While stirring the mixed liquid, 400 parts of ion exchange water was added dropwise at a rate of 2 parts / minute to emulsify. After the dropwise addition was completed, the emulsion was returned to 25°C to obtain a resin particle dispersion in which resin particles with a volume average particle size of 200 nm were dispersed. Ion exchange water was added to the resin particle dispersion to adjust the solid content to 20%, thereby preparing an amorphous polyester resin particle dispersion (A1).

[0406] (Preparation of Crystalline Polyester Resin Particle Dispersion Liquid (C1))

[0407] 1,10-Decanedicarboxylic acid: 98 parts

[0408] ·Sodium 5-sulfonate dimethyl isophthalate: 24 parts

[0409] 1,9-nonanediol: 100 parts

[0410] Dibutyltin oxide (catalyst): 0.3 parts

[0411] After adding the above components to the three-necked flask after heating and drying, the air in the container was placed in an inert atmosphere by decompression operation with nitrogen, and stirring and reflux were performed at 180°C for 5 hours by mechanical stirring. Thereafter, the temperature was gradually raised to 230°C under reduced pressure, stirred for 2 hours, and air-cooled when it became viscous to stop the reaction and obtain a crystalline polyester resin. In the molecular weight measurement (polystyrene conversion), the weight average molecular weight (Mw) of the crystalline polyester resin was 9700, and the melting temperature was 78°C.

[0412] 90 parts of the obtained crystalline polyester resin, 1.8 parts of anionic surfactant NEOGEN RK (Daiichi Kogyo Seiyaku) and 210 parts of ion exchange water were heated to 100° C., dispersed with Ultraturrax T50 manufactured by IKA, and then dispersed for 1 hour with a pressure jet type GAULIN homogenizer to prepare a crystalline polyester resin particle dispersion (C1) having a volume average particle size of 200 nm and a solid content of 20%.

[0413] (Preparation of Anti-adhesive Particle Dispersion Liquid)

[0414] Paraffin wax (HNP-9 manufactured by Nippon Seira Co., Ltd.): 100 parts

[0415] Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part

[0416] Ion exchange water: 350 parts

[0417] The above materials were mixed and heated to 100° C., dispersed using a homogenizer (Ultraturrax T50 manufactured by IKA), and then dispersed using a Manton Gaulin high pressure homogenizer (manufactured by Gaulin) to obtain a release agent particle dispersion (solid content 20%) in which release agent particles having a volume average particle size of 200 nm were dispersed.

[0418] (Preparation of Black Colored Particle Dispersion Liquid)

[0419] Carbon black (Regal 330 manufactured by Cabot Corporation): 50 parts

[0420] Anionic surfactant NEOGEN RK (Daiichi Kogyo Pharmaceutical): 5 parts

[0421] Ion exchange water: 192.9 parts

[0422] The above components were mixed and treated at 240 MPa for 10 minutes using ULTIMIZER (manufactured by Sugino Machine Co., Ltd.) to prepare a black colored particle dispersion (solid content: 20%).

[0423] (Preparation of Toner Particles (A1))

[0424] Ion exchange water: 200 parts

[0425] Amorphous polyester resin particle dispersion (A1): 150 parts

[0426] Crystalline polyester resin particle dispersion (C1): 10 parts

[0427] Black coloring particle dispersion: 15 parts

[0428] Anti-sticking agent particle dispersion: 10 parts

[0429] Anionic surfactant (TaycaPower): 2.8 parts

[0430] The above materials were added to a round stainless steel flask, 0.1N nitric acid was added, and the pH was adjusted to 3.5. Then, a PAC aqueous solution prepared by dissolving 2.0 parts of polyaluminum chloride (PAC, manufactured by Oji Paper Co., Ltd.: 30% powder) in 30 parts of ion exchange water was added. After dispersion at 30°C using a homogenizer (Ultraturrax T50 manufactured by IKA), the mixture was heated to 45°C in a heating oil bath and maintained until the volume average particle size reached 4.8 μm. Thereafter, 60 parts of amorphous polyester resin particle dispersion (A1) were added and maintained for 30 minutes. Thereafter, when the volume average particle size reached 5.2 μm, 60 parts of amorphous polyester resin particle dispersion (A1) were further added and maintained for 30 minutes. Next, 20 parts of a 10% NTA (nitrilotriacetic acid) metal salt aqueous solution (Chelest 70: manufactured by Chelest Co., Ltd.) were added, and the pH was adjusted to 9.0 using a 1N sodium hydroxide aqueous solution. Then, 1.0 part of anionic active agent (Tayca Power) was added, and the mixture was heated to 85° C. and maintained for 5 hours while being stirred. Then, the mixture was cooled to 20° C. at a rate of 20° C. / min, filtered, washed thoroughly with ion exchange water, and dried to obtain toner particles (A1) having a volume average particle size of 6.0 μm.

[0431] (Preparation of Toner (A1))

[0432] 100 parts of toner particles (A1), 1.5 parts of first silica particles (S1), and 0.5 parts of titanium oxide particles having a number average particle size of 20 nm as inorganic oxide particles were mixed, mixed at a rotation speed of 13,000 rpm for 30 seconds using a sample grinder, and sieved with a vibration sieve having a mesh size of 45 μm to obtain toner (A1).

[0433] (Preparation of Toners (A2) to (A12) and (cA1) to (cA8))

[0434] Except that the kind of the first silica particles was set to the specifications shown in Table 2, the same procedure as in the toner (A1) was carried out to obtain each toner.

[0435] (Preparation of Developers (A1) to (A12) and (cA1) to (cA8))

[0436] 10 parts of each toner and 100 parts of the following resin-coated carrier were added to a V-type mixer and stirred for 20 minutes, followed by sieving with a vibrating sieve having a mesh size of 212 μm to obtain a developer.

[0437] ·Mn-Mg-Sr ferrite particles (average particle size 40 μm): 100 parts

[0438] Toluene: 14 parts

[0439] Polymethyl methacrylate: 2 parts

[0440] Carbon black (VXC72: manufactured by Cabot Corporation): 0.12 parts

[0441] The above materials except the ferrite particles and glass beads (1 mm in diameter, the same amount as toluene) were mixed and stirred at 1200 rpm for 30 minutes using a sand mill manufactured by Kansai Paint Co., Ltd. to obtain a dispersion. The dispersion and the ferrite particles were added to a vacuum degassing kneader, and the mixture was decompressed and dried while being stirred to obtain a resin-coated carrier.

[0442] [Table 2]

[0443]

[0444] [Examples 1 to 28 and Comparative Examples 1 to 8]

[0445] According to Table 3, the image forming apparatus (1) shown below was prepared.

[0446] (Case of image forming apparatus (1): DH1 method)

[0447] As the image forming apparatus (1), an image forming apparatus (a modified machine of the product name "Versant 80 Press" manufactured by Fuji Xerox Co., Ltd.) was prepared. Figure 2 A similar structure is modified to be a device having a fixing device in which a contact area between a fixing belt and a pressure roller is directly heated by a halogen lamp. In addition, a developer shown in Table 3 is contained in a developing device of the image forming device, and a replenishing toner (the same toner as the toner contained in the developer) is placed in a toner box.

[0448] (Evaluation of Low-temperature Fixability)

[0449] The image forming apparatus of each example was evaluated for low-temperature fixing properties.

[0450] The toner loading on J paper (A4) is 4.0 g / m 2Ten patches of 20 cm × 20 cm were printed at a fixed processing speed of 140 mm / sec and a fixing temperature of 110°C. The images of the first, fifth, and tenth patches were evaluated according to the following criteria. The evaluation results are the average of the first, fifth, and tenth patches.

[0451] The evaluation criteria are as follows: The allowable range is A to B.

[0452] A: There is no unevenness in the image

[0453] B: Slightly uneven image

[0454] C: There is obvious unevenness in the image

[0455] D: There is white leakage in the image

[0456] [Table 3]

[0457]

[0458] As shown in Table 3, it can be seen that the image forming apparatus of Example can suppress the occurrence of variation in low-temperature fixing property compared with the image forming apparatus of Comparative Example.

Claims

1. An image forming device comprising: An electrophotographic photoreceptor having a photosensitive layer; an electrostatic image forming unit that forms an electrostatic image on the surface of the charged electrophotographic photoreceptor; a developing unit containing an electrostatic image developer including a toner for developing an electrostatic image, and developing a toner image formed on the surface of the electrophotographic photoreceptor by the electrostatic image developer; a transfer unit that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium; and a fixing unit that fixes the toner image transferred onto the surface of the recording medium to the recording medium; The fixing unit comprises: a fixing belt in contact with the toner image transferred to the surface of the recording medium; a rotating body which contacts with the outer peripheral surface of the fixing belt and is arranged so as to form a contact area with the fixing belt, and rotates together with the fixing belt in the contact area to transport the recording medium; and a heating source that heats the contact area between the fixing belt and the rotating body, The electrostatic image developing toner contains toner particles and silica particles, wherein the silica particles have a number average particle size of 110 nm or more and 130 nm or less, a large diameter side number particle size distribution index, i.e., an upper side GSDp, which is less than 1.080, an average circularity of 0.94 or more and 0.98 or less, and a proportion of particles with a circularity of 0.92 or more is 80% by number or more.

2. The image forming apparatus according to claim 1, in, The large-diameter-side number size distribution index of the silica particles, that is, the upper GSDp, is less than 1.

075.

3. The image forming apparatus according to claim 1 or 2, in, The silica particles have a smaller diameter number size distribution index, that is, a lower GSDp, which is less than 1.

080.

4. The image forming apparatus according to claim 1 or 2, in, The average circularity of the silica particles is 0.95 or more and 0.97 or less.

5. The image forming apparatus according to claim 1 or 2, in, The ratio of the silica particles having a circularity of 0.92 or more is 85% by number or more.

6. The image forming apparatus according to claim 1 or 2, in, The electrostatic image developing toner further includes inorganic oxide particles having a number average particle diameter of 5 nm or more and 50 nm or less.

7. The image forming apparatus according to claim 1 or 2, in, The toner particles contain a styrene acrylic resin as a binder resin.

8. The image forming apparatus according to claim 1 or 2, in, The toner particles contain a non-crystalline polyester resin as a binder resin.

9. The image forming apparatus according to claim 1 or 2, in, The fixing unit further includes a pressure member, which is provided on the inner peripheral surface side of the fixing belt and presses the fixing belt together with the rotating body in the contact area. The heating source is a heating source that heats the contact region via the pressurizing member.

10. The image forming apparatus according to claim 9, in, The heating source is a halogen lamp.

11. The image forming apparatus according to claim 10, in, The image forming apparatus has a reflecting member that reflects radiant heat from the halogen lamp toward the contact area.

12. The image forming apparatus according to claim 11, in, A heat insulating member is provided between a side edge of the reflecting member and an inner peripheral surface of the fixing belt facing the side edge.

13. The image forming apparatus according to claim 1 or 2, in, The fixing unit includes a pressing member on the downstream side of the contact region, the pressing member pressing the rotating body from the inner side of the fixing belt.

14. The image forming apparatus according to claim 13, in, The rotating body has an elastic layer on a surface on a side pressed against the fixing belt.

15. The image forming apparatus according to claim 14, in, The pressing member is configured to elastically deform the elastic layer.

16. The image forming apparatus according to claim 13, in, The pressing member is configured to elastically deform the elastic layer locally at the discharge side of the fixing unit.

17. The image forming apparatus according to claim 1 or 2, in, The heating source is a linear heating element.

18. The image forming apparatus according to claim 17, in, The fixing unit includes a current supplying portion for supplying pulse current to the linear heating element.

19. The image forming apparatus according to claim 17, in, The fixing unit further comprises: a sliding member that slides with the linear heating element; and a power supply unit that performs pulse power supply to the linear heating element. and a cooling section that cools a fixed image after the toner image transferred to the surface of the recording medium is fixed, The contact region is heated from the linear heating element via the sliding member.

20. The image forming apparatus according to claim 1 or 2, in, The fixing unit is an electromagnetic induction heating fixing unit.

21. The image forming apparatus according to claim 20, in, The fixing unit includes an electromagnetic induction heating device and has a metal layer as the heating source inside the fixing belt.

Images