JP2005301200A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device having a configuration capable of preventing leakage magnetic flux without causing problems such as overheating in view of problems in a fixing device using an electromagnetic fluid heating method.
In a fixing device 1 for performing a fixing process by bringing a fixing member 101, 102, 103, 104 heated using an electromagnetic induction heating method into contact with a visible image, the fixing members 101, 102, 103, Magnetic flux generated from the electromagnetic induction heating member 105 in a state in which the passage portion 200A of the recording medium S that is arranged at a position where the 104 can be surrounded and carries a visible image contacting the fixing members 101, 102, 103, 104 is provided. It is characterized by having a structure 200 for attenuating or shielding.
[Selection] Figure 4

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly, to a mechanism for shielding leakage magnetic flux for a configuration using an electromagnetic induction heating method.

In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine, an image output is obtained by transferring a visible image such as a toner image carried on a latent image carrier to a recording medium such as a recording sheet. It is supposed to be.
The toner image included in the visible image is fixed on the recording medium by melting and permeating action due to heat and pressure when passing through the fixing device.

  The heating system employed in the fixing device includes a heating roller using a halogen lamp or the like as a heat source and a pressure roller that is in contact with the heating roller. There are also a film fixing method using a film having a small heat capacity as a heating member, and a fixing method using an electromagnetic induction heating method as a heating method (for example, Patent Document 1).

  In Patent Document 1, an induction heating coil mounted on a bobbin is provided inside the heating roller, and an electric current is applied to the induction heating coil to generate an eddy current in the heating roller so that the heating roller generates heat. It has been. In this configuration, there is an advantage that it is possible to instantaneously raise the temperature to a predetermined temperature without the need for residual heat unlike the heat roller fixing method.

FIG. 10 is a view showing an example of a fixing device using an induction heating method. The fixing device shown in FIG. 10 is equipped with a heating body 120 including an exciting coil unit 118 and a magnetic metal member 119 as a heating unit. The film inner surface guide 121, the cylindrical film 117 having heat resistance that wraps the film inner surface guide 121 with the magnetic metal member 119 in contact with the inner wall, and the film 117 are pressed against the film 117 at the position of the magnetic metal member 119. A fixing nip portion N is formed between the lever film 117 and the pressure roller 122 that rotates the film 117.
The film 117 has a film thickness of 100 μm or less, preferably 50 μm or less and 20 μm or more, and has a heat resistance of a single layer film such as PTFE, PFA, FEP or the like, or an outer peripheral surface of a film such as polyimide, polyamideimide, PEEK, PES, PPS, etc. A composite layer film coated with PTFE, PFA, FEP or the like is used.
The film inner surface guide 121 is made of a member having rigidity and heat resistance formed of a resin such as PEEK or PPS, and the heating body 120 is fitted in the substantially central portion in the longitudinal direction of the film inner surface guide 121. .
The pressure roller 122 is composed of a core 122a and a heat-resistant rubber layer 122b having good releasability such as silicone rubber provided around the core 122a, and a predetermined pressing force is applied by a bearing or an urging means (both not shown). The film 117 is held so as to be in pressure contact with the magnetic metal member 119 of the heating body 120. The pressure roller 122 is rotated counterclockwise by a driving means (not shown).
By the rotational driving of the pressure roller 122, a frictional force is generated between the pressure roller 122 and the film 117, and the rotational force acts on the film 117. The film 117 is in close contact with the magnetic metal member 119 of the heating body 120. Slide and rotate.
A recording having an unfixed toner image T formed by an image forming unit (not shown) between the film 117 in the fixing nip N and the pressure roller 122 in a state where the heating body 120 reaches a predetermined temperature. The material S is introduced. The recording material S is sandwiched between the pressure roller 122 and the film 117 and conveyed through the fixing nip portion N, whereby the heat of the magnetic metal member 119 is applied to the recording material S through the film 117, and the unfixed toner image T Is melt-fixed on the recording material S. At the exit of the fixing nip N, the recording material S that has passed is separated from the surface of the film 117 and conveyed to a paper discharge tray (not shown).
As described above, in the electromagnetic induction heating type fixing device, the magnetic metal member 119 as the induction heating means is disposed close to the toner image T of the recording material S via the film 117 by utilizing the generation of eddy current. Therefore, the heating efficiency is further improved as compared with the fixing device of the film heating type.

By the way, when the heat generation phenomenon due to electromagnetic induction heating is used, heat is generated using an eddy current generated when a magnetomotive force generated by applying a current to the induction heating coil is transmitted to the object to be heated. However, the magnetic field lines generated by the magnetomotive force, that is, a part of the so-called magnetic flux may leak to the periphery.
In this case, there is a risk of adverse effects due to electromagnetic waves on the electrical components arranged around or the human body. Thus, conventionally, a configuration in which a magnetic shield for shielding leakage magnetic flux is arranged in the vicinity of the induction heating coil is known (for example, Patent Documents 2, 3, and 4).

JP 2001-13805 (paragraph “0021” column) Japanese Patent Laid-Open No. 06-292630 (paragraph “0020” column) JP 2002-91206 A (paragraph “0027” column) JP 2003-17221 A (paragraph “0031” column)

  When shielding the leakage magnetic flux when using the heat generation phenomenon due to energization of the induction heating coil, if this is a heating roller or heating film, which is a heating member in the fixing device, the leakage flux around the heating roller or heating film This is set as the shielding position.

However, in this configuration, due to the influence of heat generated in the fixing device, the ambient temperature around the heating roller and the heating film, which are shielding objects, increases, and as a result, the shielding space may be overheated. .
If an overheat condition occurs in the shielded space, for example, evaporation of the offset preventive agent or deterioration of the durability of the members constituting the fixing device may be caused, and contamination due to image contamination due to the occurrence of offset or toner adhesion to the fixing member. And problems such as deteriorating the service life of parts occur.
In addition, as disclosed in Patent Document 3, a shielding position is not specially provided, and the outer cover of the fixing device may be a shielding position. In this case, there is no shielding member on the outside. Although it is necessary to reliably prevent magnetic flux leakage, no measures have been taken for this purpose.

  An object of the present invention is to prevent leakage magnetic flux without using a special shielding position or structure without causing problems such as overheating in view of the problems in the above-described conventional fixing device, particularly a fixing device using an electromagnetic fluid heating method. It is an object of the present invention to provide a fixing device and an image forming apparatus having a configuration capable of achieving the above.

  According to a first aspect of the present invention, there is provided a fixing device that performs a fixing step by bringing a fixing member heated using an electromagnetic induction heating method into contact with a visible image, and is disposed at a position where the fixing member can be surrounded. It is characterized in that it has a structure for attenuating or shielding the magnetic flux generated from the electromagnetic induction heating member in a state in which the recording medium passage portion is in contact with the fixing member.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, as the magnetic flux shielding structure, a housing that houses the fixing member is made of a material that can absorb magnetic force or attenuate magnetic force. .

  According to a third aspect of the present invention, in the fixing device according to the first aspect, as the magnetic flux shielding structure, a casing is provided that surrounds a casing housing the fixing member, and the casing is magnetically absorbed or attenuated. It is characterized by being composed of possible materials.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, in the case where the recording medium passes through the casing or casing, a magnetic absorption is provided in the same manner as the casing or casing. A cover member made of a flexible member made of a material capable of reducing the magnetic property or the magnetic force is provided, and the cover member is characterized in that the passage portion can be opened by the passage of the recording medium.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, an iron-based material is used as a material used for the magnetic flux shielding structure.

  According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, a conductive non-ferrous material is used as a material used for the magnetic flux shielding structure.

  According to a seventh aspect of the present invention, in the fixing device according to any one of the first to sixth aspects, the housing or casing used for the shielding structure is provided with a heat radiating portion. .

  According to an eighth aspect of the present invention, in the fixing device according to any one of the first to sixth aspects, a metal powder or a metal compound and a resin are mixed in the casing or casing used for the shielding structure. It is characterized in that the constructed variable magnetic field shielding material is used.

  According to a ninth aspect of the present invention, in the fixing device according to the eighth aspect, the heat radiating portion is configured by an opening capable of communicating between the inside and the outside of the housing or the casing.

  According to a tenth aspect of the present invention, in the fixing device according to the ninth aspect, the opening is single or plural.

  According to an eleventh aspect of the present invention, in the fixing device according to the ninth or tenth aspect, when a single opening is provided, a wire mesh having a ventilation portion is disposed in the opening.

  According to a twelfth aspect of the present invention, in the fixing device according to the tenth aspect of the present invention, the opening has the same heat dissipating area regardless of whether the opening is single or plural.

  A thirteenth aspect of the invention is characterized in that the fixing device according to one of the first to twelfth aspects is used for an image forming apparatus.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the recording medium conveyed to the fixing device accommodates a latent image carrier, a developing device, and a latent image carrier cleaning device. It is characterized in that it is disposed on the discharge path of the recording medium in the process cartridge.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to the fourteenth aspect, the developer used for the visible image processing of the electrostatic latent image formed on the latent image carrier used in the developing device. A prepolymer composed of a modified polyester resin in an organic solvent, a compound that stretches or crosslinks with the prepolymer, and a toner composition are dissolved or dispersed, and the solution or dispersion is subjected to a crosslinking reaction and / or in an aqueous medium. It is characterized by using a polymerized toner obtained by an extension reaction and removing the solvent from the obtained dispersion.

  According to a sixteenth aspect of the present invention, in the image forming apparatus according to the fourteenth or fifteenth aspect, as the polymerized toner, the dispersed particle diameter of the pigment-based colorant dispersed in the polymerized toner is 0.5 (number average diameter). The number average diameter is 0.7 (μm) or more and the number ratio is 5 (%) or less.

  According to a seventeenth aspect of the present invention, in the image forming apparatus according to one of the fourteenth to sixteenth aspects, the dispersed particle diameter is 0.3 in terms of a number average diameter as the colorant that is a constituent component of the polymerized toner. (Μm) or less, and the number average diameter thereof is 10 (%) or less.

  According to an eighteenth aspect of the present invention, in the image forming apparatus according to any one of the fourteenth to seventeenth aspects, the weight average particle size of the polymerized toner is 3.0 (μm) or more and 7.0 ( μm) or less, and the particle size distribution is 1.00 ≦ Dv / Dn ≦ 1.20 (Dv: weight average particle size, Dn: number average particle size).

  According to a nineteenth aspect of the present invention, in the image forming apparatus according to any one of the fourteenth to eighteenth aspects, the circularity of the polymerized toner is 0.900 or more and 0.960 or less. It is said.

  According to a twentieth aspect of the present invention, in the image forming apparatus according to any one of the fourteenth to nineteenth aspects, in the molecular weight distribution of the tetrahydrofuran-soluble content of the polyester resin contained in the polymerized toner, the molecular weight is 2500 to 500. A main peak exists in the region of 10,000, and the number average molecular weight is in the range of 2500 to 50000.

  The invention according to claim 21 is the image forming apparatus according to any one of claims 14 to 20, wherein the glass transition point of the polyester resin contained in the polymerized toner is 40 to 65 (° C), The acid value is 1 to 30 (mgKOH / g).

  According to a twenty-second aspect of the present invention, in the image forming apparatus according to any one of the fourteenth to twenty-first aspects, the oil-based dispersion of the polymerized toner dissolves the non-reactive polyester-based resin. It is characterized by being.

  According to a twenty-third aspect of the present invention, in the image forming apparatus according to any one of the fourteenth to twenty-second aspects, a developer containing the polymerized toner and a carrier is used.

  According to the first to third aspects of the present invention, the structure surrounding the fixing member except for the passage portion of the recording medium is provided with a structure capable of absorbing or attenuating the magnetic flux. Even when the heating method is used, it is possible to prevent the adverse effect on the peripheral portion due to the configuration for preventing the leakage of magnetic flux and speeding up the rise to the fixing temperature.

  In particular, in the invention described in claim 2, a housing that accommodates the fixing member that is closest to the fixing member that is the source of magnetic flux is used as a magnetic flux attenuation or shielding member, and in the invention described in claim 3. In the invention according to claim 2, the leakage flux generating source itself can be shielded by using a casing surrounding the casing as a magnetic flux attenuation or shielding member. In the invention, a shielding structure for leakage magnetic flux using a multiple wall surface structure can be obtained. In particular, in the invention described in claim 3, by using a casing positioned around the outer periphery of the fixing member for preventing leakage of magnetic flux, it can be detached from the casing of the fixing device. The operability can be prevented from being impaired.

  According to the fourth aspect of the present invention, since the cover member is provided in the passage portion of the recording medium and the cover member does not impair the passage of the recording medium, the leakage point of the magnetic flux, that is, the inside and outside of the fixing device It is possible to more effectively prevent magnetic flux leakage by reducing the number of communicating portions.

  According to the fifth aspect of the present invention, since the material used for the magnetic flux shielding structure is iron-based, it is possible to increase the magnetic permeability and suppress the leakage by promoting the absorption of the magnetic flux.

  According to the sixth aspect of the present invention, since the material used for the magnetic flux shielding structure is a conductive non-ferrous material, the magnetic flux that is to leak due to the reverse magnetic flux generated by the eddy current when the magnetic flux is transmitted. Can be effectively attenuated.

  According to the seventh aspect of the present invention, since the heat radiating portion is provided in the housing or the casing, the fixing member is easily received when the magnetic flux shielding structure is provided in a state of surrounding the fixing member. It is possible to prevent overheating.

  According to the invention described in claim 8, since the casing or casing used for the shielding structure is a variable magnetic field shielding material in which metal powder or a metal compound and a resin are mixed, unlike a metal casing or the like, It is possible to suppress an abnormally high temperature at the part touched by the hand. As a result, it is possible to suppress an inadvertent temperature rise in the outer space of the fixing device exposed to the outside and its peripheral part, and prevent the occurrence of unforeseen circumstances such as adverse effects on peripheral devices due to the temperature rise. It becomes possible to do.

  According to the ninth aspect of the present invention, since the heat radiating portion is configured by the opening, it is possible to prevent internal overheating with a simple configuration.

  According to the tenth aspect of the present invention, since there is a single or a plurality of openings, it is possible to set an optimum heat radiation area for preventing overheating at the fixing member accommodation position.

  According to the eleventh aspect of the present invention, since the wire mesh having the ventilation portion is provided in the opening, the leakage magnetic flux from the opening can be absorbed or attenuated by the wire mesh, and heat is radiated in accordance with the suppression of the leakage magnetic flux. Is possible.

  According to the twelfth aspect of the present invention, since the heat radiation area in the opening is the same regardless of whether a single or a plurality of openings are provided, it is possible to secure a necessary heat radiation amount.

  According to the thirteenth aspect of the present invention, the leakage magnetic flux in the fixing device is suppressed and the overheating that may occur in the configuration for the suppression is surely prevented to prevent adverse effects such as evaporation of the offset preventive agent. It is possible to obtain an image forming apparatus capable of preventing problems such as occurrence of image and image fouling.

  According to the fourteenth aspect of the present invention, the fixing device having a configuration capable of preventing the leakage of magnetic flux is disposed on the storage medium discharge path from the process cartridge in which the latent image carrier, the developing device, and the cleaning device are collectively accommodated. Even in the case of targeting the configured structure, there is no thermal adverse effect on the process cartridge. Thus, the durability of the latent image carrier accommodated in the process cartridge and the developer in the developing device is not impaired.

  According to the fifteenth to twenty-third aspects of the present invention, even when a polymerized toner that is easily affected by frictional charging is used as a toner used to obtain high definition and high image quality, an overheated state at the position where the fixing member is disposed. As a result, it is possible to prevent the toner from being reattached to the fixing member due to frictional charging caused by the speed difference caused by the change in thermal expansion between the fixing members, thereby preventing the contamination.

  The best mode for carrying out the present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a diagram showing one of image forming apparatuses to which the fixing device according to the present embodiment is applied, and the configuration thereof will be described below.
The image forming apparatus shown in FIG. 1 uses a copying machine or a printer that can form a full-color image by the above-described quadruple tandem method.
In addition to this, there is a facsimile apparatus capable of performing the same image forming process as the above-described copying machine and printer based on a received image signal. Note that the image forming apparatus includes not only the above-described color image but also an apparatus that targets a single color image.

  The image forming apparatus 20 shown in FIG. 1 forms a color image directly from a latent image carrier onto a recording sheet by superimposing and transferring an image for each color separation onto a recording sheet such as paper adsorbed to a transfer belt used as a transfer body. Is used.

In FIG. 1, an image forming apparatus 20 includes the following apparatuses.
Image forming devices 21Y, 21M, 21C, and 21BK that form images of respective colors according to the original image, transfer devices 22 that are arranged to face the image forming devices 21Y, 21M, 21C, and 21BK, and the respective image forming devices A first paper feed cassette 24A, a first paper feed cassette 24A provided in a paper feed device 24, a manual feed tray 23 as a sheet supply means for feeding a recording sheet to a transfer area where the devices 21Y, 21M, 21C, 21BK and the transfer device 22 face each other. Two sheet feeding cassettes 24B, registration rollers 30 for supplying the recording sheets conveyed from the manual feed tray 23 and the sheet feeding cassettes 24, 24 in accordance with the image forming timings of the image forming apparatuses 21Y, 21M, 21C, 21BK; A fixing device 1 that fixes a sheet-like medium after transfer in a transfer region. In this embodiment, a recording sheet carrying a toner image is targeted as a fixing target. However, depending on the transfer format, a transfer body that comes into contact with the photosensitive member without passing through a recording medium such as a recording sheet, that is, simultaneously with the transfer. It is also possible to target a medium for fixing.

  As will be described in detail later, the fixing device 1 is configured to employ a belt fixing system in which a heated belt is disposed on the side facing the image. For this reason, the fixing device 1 is equipped with a heat source for heating the belt and a fixing roller and a pressure roller that constitute a nip portion that is a fixing region while nipping and conveying the sheet facing the belt, and the belt is fixed. It is configured to pass between the roller and the heat source and pass through the nip portion.

  The transfer device 22 uses a belt (hereinafter referred to as a transfer belt) 22A that is wound around a plurality of rollers as a transfer body. The details will be described with reference to FIG. Transfer bias means 22Y, 22M, 22C, and 22BK for applying a transfer bias are respectively disposed at the opposing positions, and the first color is transferred in the moving direction of the transfer belt 22A (the direction indicated by the arrow in FIG. 1). On the side, an attracting bias means 31 for applying an attracting bias for attracting the recording sheet to the transfer belt 22A prior to the transfer of the first color is disposed so as to be in contact with the transfer belt 22A.

The image forming apparatus 20 has a larger heat capacity than that of paper such as plain paper generally used for copying, 90K paper such as OHP sheets, cards, postcards, thick paper equivalent to about 100 g / m ² or more, and envelopes. Any so-called special sheet can be used as the recording sheet.

FIG. 2 is a diagram showing details of each image forming device. In FIG. 2, each image forming device 21Y, 21M, 21C, 21BK develops each color of yellow, magenta, cyan, and black. Although the toner colors to be used are different, the configuration is the same. Therefore, the configuration of the image forming device 21Y will be described as a representative of the image forming devices 21M, 21C, and 21BK.
The image forming device 21Y includes a photosensitive drum 25Y as an electrostatic latent image carrier, a charging device 27Y arranged in order along the rotation direction of the photosensitive drum 25Y (clockwise in the configuration shown in FIG. 2), and a developing device. 26Y and a cleaning device 28Y, and an electrostatic latent image corresponding to image information corresponding to the color separated by the writing light 29Y from the writing device 29 is formed between the charging device 27Y and the developing device 26Y. Is used. In addition to the drum shape, the electrostatic latent image carrier may have a belt shape. In the image forming apparatus 20 shown in FIG. 1, since the transfer device 22 extends obliquely, the space occupied by the transfer device 22 in the horizontal direction can be reduced.

In the image forming apparatus 20 having the above configuration, image formation is performed based on the following steps and conditions. In the following description, an image forming apparatus in which image formation is performed using the magenta toner denoted by reference numeral 21Y on behalf of each image forming apparatus will be described, but the same applies to other image forming apparatuses. Preface.
At the time of image formation, the photosensitive drum 25Y is rotationally driven by a main motor (not shown), is neutralized by an AC bias (DC component is zero) applied to the charging device 27Y, and the surface potential is set to a reference potential of about −50V. Is done.
Next, the photosensitive drum 25Y is uniformly charged to a potential substantially equal to the DC component by applying a DC bias superimposed with an AC bias to the charging device 27Y, and its surface potential is approximately −500 V to −700 V (target). The charging potential is determined by a process control unit).

  When the photosensitive drum 25Y is uniformly charged, a writing process is executed. An image to be written is written for forming an electrostatic latent image using a writing device 29 in accordance with digital image information from a controller unit (not shown). That is, in the writing device 29, laser light from a laser light source that emits light based on a laser diode light emission signal binarized for each color corresponding to digital image information is converted into a cylinder lens (not shown), a polygon motor 29A, A photosensitive drum carrying an image for each color through an fθ lens (not shown), first to third mirrors, and a WTL lens. In this case, the photosensitive drum 25Y is irradiated and irradiated for convenience. The surface potential on the surface of the photosensitive drum of the portion thus made becomes approximately −50 V, and an electrostatic latent image corresponding to the image information is formed.

  The electrostatic latent image formed on the photosensitive drum 25Y is subjected to visible image processing by using a toner having a color complementary to the color separation color by the developing device 26Y. In the developing process, an AC bias is applied to the developing sleeve. The toner (Q / M: -20 to -30 μC / g) is developed only in the image portion where the potential is lowered by the irradiation of the writing light by applying DC: −300 V to −500 V with the superimposed toner, and the toner image Is formed.

Each color toner image that has undergone a visible image process in the development process is transferred to a recording sheet that is fed out with registration timing set by a registration roller 30, but the recording sheet is transferred to a roller before reaching the transfer belt 22A. The sheet is biased to the transfer belt 22A by application of a suction bias by the sheet suction bias means 31 configured as described above.
A recording sheet electrostatically attracted to the transfer belt 22A and transported and moved together with the transfer belt 22A (for convenience, indicated by a symbol S in FIG. 2) is mounted on the transfer device 22 at a position facing the photosensitive drum in each image forming device. The toner image is electrostatically transferred from the photosensitive drum by applying a bias having a polarity opposite to that of the toner by the transfer bias means 22Y, 22M, 22C, and 22BK.

  The transfer paper that has undergone the transfer process for each color is separated from the transfer belt 22A by the drive side roller (for convenience, indicated by reference numeral 22A1 in FIG. 2), and is conveyed toward the fixing device 1 (see FIG. 1). Then, the toner image is fixed to the transfer sheet S by passing through a fixing nip constituted by a fixing belt and a pressure roller. Thereafter, in the case of single-sided printing, the in-body discharge tray 32 (see FIG. 1). Or, it is discharged to the external paper discharge tray 33 (see FIG. 1).

An image forming apparatus 20 shown in FIG. 1 has a configuration capable of forming an image on both sides of a recording sheet.
In FIG. 1, the recording sheet S that has passed through the fixing device 1 is conveyed toward the double-side reversing unit 34 when the double-sided image forming mode is selected in advance, and the first side and the second side within the unit 34. Are reversed and then transported to the duplex transport unit 35. The recording sheet S conveyed from the double-sided conveyance unit 35 is conveyed toward the registration roller 30 and fed out toward the transfer position as in the case of image formation on one side. The recording sheet S that has completed the image formation on the first surface and the second surface of the recording sheet S and has passed through the fixing device 1 is discharged to one of the paper discharge units in the same manner as in the image formation on one side. . In FIG. 2, reference numeral 36 denotes a cleaning device for the transfer belt 22A.

  The transfer belt 22A provided in the transfer device 22 is wound around a plurality of rollers including the driving roller 22A1, and has a stretched surface facing each image forming unit. Further, when forming a monochrome image instead of a full-color image, the transfer belt 22A is not black so that the sheet is opposed only to the black image forming unit 21BK and the sheet is not opposed to the image forming unit other than black. It is set as the structure which can leave | separate (state shown with a dashed-two dotted line in FIG. 1) from this image-forming part.

  Each of the image forming devices 21Y, 21M, 21C, and 21BK is provided with a process cartridge in which a charging device, a photosensitive drum, a developing device, and a cleaning device are collectively housed among devices related to image formation. Employs a configuration that can be inserted into and removed from the main body of the image forming apparatus.

The following characteristics are set as the developer used in the developing device in this embodiment.
First, a toner used as a developer dissolves or disperses a prepolymer made of a modified polyester resin, a compound that stretches or crosslinks with the prepolymer, and a toner component in an organic solvent, and the solution or dispersion is dissolved in an aqueous system. A polymerized toner obtained by performing a crosslinking reaction and / or an extension reaction in a medium and removing a solvent from the obtained dispersion, and the polymerized toner includes a pigment-based colorant dispersed in the polymerized toner. A dispersion having a number average particle diameter of 0.5 (μm) or less and a number ratio of the number average diameter of 0.7 (μm) or more being 5 (%) or less is used.
Further, as the colorant that is a constituent component of the polymerized toner, those having a dispersed particle diameter of 0.3 (μm) or less in number average diameter and a number average diameter of 10 or less (%) are used. Yes. The weight average particle size of the polymerized toner is 3.0 (μm) or more and 7.0 (μm) or less, and the particle size distribution is 1.00 ≦ Dv / Dn ≦ 1.20 (Dv: The weight average particle diameter, Dn: number average particle diameter), and the circularity of the polymerization toner is 0.900 or more and 0.960 or less.

  In addition, in the molecular weight distribution of the tetrahydrofuran-soluble portion of the polyester resin contained in the polymerized toner, a main peak exists in the region of the molecular weight 2500 to 10,000, and the number average molecular weight is set in the range of 2500 to 50000, The polyester resin contained in the polymerized toner has a glass transition point of 40 to 65 (° C.) and an acid value of 1 to 30 (mg KOH / g).

  The oil dispersion of the polymerized toner has a structure in which an amine and a non-reactive polyester resin are dissolved, and the polymerized toner is mixed with a carrier and used as a developer.

Details of the developer described above will be described below.
In recent years, a toner by a polymerization method (hereinafter referred to as “polymerized toner”) has been widely used due to a demand for higher image quality. In order to overcome the problems of the conventionally used pulverized toner, the polymerized toner manufacturing method does not include a pulverizing step, so that the toner does not require a kneading step and a pulverizing step. Cost-saving contributions such as saving, shortening production time and improving product yield are significant. In addition, the particle size distribution in the polymerized toner particles obtained by such a polymerization method is easy to form a sharp distribution as compared with the particle size distribution of the toner by the pulverization method, and it is easy to encapsulate the wax. It is possible to greatly improve the performance. Further, it is advantageous in terms of charging stability and transferability as compared with a toner obtained by a pulverization method, and it is easy to obtain a spherical toner.

  However, the polymerized toner has many problems that have not been solved yet. When a polymerized toner is used as an image forming substance in the belt fixing type fixing device, there is a problem that electrostatic offset appears more conspicuously than when a conventional pulverized toner is used. Even when compared with the case where a cleaning device is provided to clean the toner adhering to the belt, the amount of toner collected by the cleaning device is larger than that of the pulverized toner. In addition, the surface tension of the polymerized toner acts in the polymerization process, and thus the sphericity of the particles is high. However, the toner physical properties are still not sufficient as described below, for example. Also, it is not easy to control (atypical) the shape of the toner.

  In the production method of toner by suspension polymerization method widely used in the polymerization method, the monomer for binder (binder resin) used in the method is limited to styrene monomer and acrylic monomer which are harmful to human body. Since the toner to be contained contains these components, there is an environmental problem. In addition, since the resulting toner encapsulates wax, when the toner is used in practice, the adhesion of the toner to the photoreceptor is reduced, but with regard to toner fixing properties, the wax exists in the form of a particle interface. Compared with the pulverization method, the encapsulated part makes it difficult for the wax to permeate the toner surface, resulting in poor fixing efficiency. Therefore, the polymerized toner becomes a disadvantageous toner for power consumption. Further, in the case of a polymerized toner, if the amount of wax is increased in order to improve the fixing property, or if the dispersed particle diameter of the wax is increased, the transparency of the color image is deteriorated when used as a color toner. It is unsuitable for use as a forming toner.

  As a method for producing the polymerized toner, there are an emulsion polymerization method and the like in which atypical modification is relatively possible in addition to the suspension polymerization method. In the emulsion polymerization method, the monomer is limited to the styrene monomer. Also in this method, the complete removal of the unreacted monomer from the toner particles and the complete removal of the emulsifier and the dispersant from the toner particles are difficult, and environmental problems due to the toner are also generated.

  A solution suspension method is known as a toner production method. In this method, there is a merit that a polyester resin that can be fixed at low temperature can be used, but in this method, since the high molecular weight component is added in the process of dissolving or dispersing the low temperature fixing resin and the colorant in the solvent, the liquid viscosity As a result, productivity problems will occur. Further, in this dissolution suspension method, toner cleaning is improved by making the surface of the toner spherical and making the surface uneven (Japanese Patent Laid-Open No. 9-15903). Since the toner is an irregularly shaped toner having no regularity, it has problems in terms of charge stability, durability and releasability, and satisfactory toner quality is not obtained.

  According to Japanese Patent Application Laid-Open No. 11-133665, a practical sphericity composed of an elongation reaction product of a urethane-modified polyester as a toner binder is improved for the purpose of improving toner fluidity, low-temperature fixability, and hot offset property. A dry toner of 90 to 1.00 has been proposed. Further, Japanese Patent Application Laid-Open No. 11-149180 and JP-A-11-149180 disclose dry toners that are excellent in powder flowability and transferability in the case of a small particle size toner and excellent in all of heat-resistant storage stability, low-temperature fixability, and hot offset resistance. 2000-292981 and the like. The toner production methods described in these publications include a high molecular weight process in which an isocyanate group-containing polyester prepolymer is subjected to a polyaddition reaction with an amine in an aqueous medium.

  However, in the case of a polymerized toner obtained by the polymerization method as described above, the dispersion of the pigment is poor, and the pigment is unevenly dispersed in the toner. Therefore, the image obtained with this toner has low transparency. The problem was that it was inferior in saturation (brightness). In particular, when a color image was formed on an OHP sheet using the toner, there was a defect that the image became a dark image.

  Next, the polymerized toner used in the examples of the present invention will be described in detail. In the polymerized toner used in the examples of the present invention, at least the polyester-based prepolymer A containing an isocyanate group is dissolved in the organic solvent, the pigment-based colorant is dispersed, and the release agent is dissolved or dispersed. An oil-based dispersion is dispersed in an aqueous medium in the presence of inorganic fine particles and / or polymer fine particles, and the prepolymer A is reacted with polyamine and / or monoamine B having an active hydrogen-containing group in this dispersion to give urea. It is obtained by forming a urea-modified polyester resin C having a group and removing the liquid medium contained in the dispersion liquid containing the urea-modified polyester resin C.

  In the urea-modified polyester resin C, the Tg is 40 to 65 (° C.), preferably 45 to 60 (° C.). The number average molecular weight Mn is 2500 to 50000, preferably 2500 to 30000. The weight average molecular weight Mw is 10,000 to 500,000, preferably 30,000 to 100,000.

  This toner contains, as a binder resin, a urea-modified polyester resin C having a urea bond that has been polymerized by the reaction between the prepolymer A and the amine B. The colorant is highly dispersed in the binder resin.

  As a result of intensive studies on the toner, the dispersed particle diameter of the pigment-based colorant contained in the toner particles defines the number average diameter to be 0.5 (μm) or less, and the number average diameter is 0.7 ( By controlling the number ratio (μm) or more to 5 (%) or less, it is excellent in low-temperature fixability, charging stability and fluidity, and gives high-quality images, and in particular, excellent transparency and glossiness. It has been found that a toner giving a color image can be obtained.

  As a result of further investigation, the dispersed particle diameter of the colorant is specified to be 0.3 (μm) or less in number average diameter, and the number ratio of the number average diameter is 0.5 (μm) or more to 10 (%) or less. It was found that higher quality toner can be obtained by controlling. Such a toner has excellent image resolving power and is suitable as a toner for a digital developing device. In particular, in the case of the color toner according to the embodiment of the present invention, a high-quality color image having excellent resolution and transparency and good color reproducibility is provided.

  In order to obtain the toner in which the colorant is uniformly dispersed, it is necessary to devise the toner production conditions. Under the conventional production conditions, it is not possible to obtain the high-quality toner as described above.

In the embodiment of the present invention, in order to obtain the high-quality toner, a step of pulverizing the colorant (wet pulverization step) when forming an oily dispersion containing the prepolymer A, the colorant and the release agent is performed. It is necessary to adopt. The wet pulverization apparatus for carrying out the wet pulverization process in this case may be any apparatus that can pulverize by applying an impact force to the colorant in the liquid, and any apparatus can be used. As such a thing, various conventionally well-known wet grinding apparatuses, for example, a ball mill, a bead mill, etc. are mentioned.
In the wet pulverization step, the temperature is 5 to 20 (° C), preferably 15 to 20 (° C).

  By adjusting the wet pulverization conditions, the dispersed particle size and particle size distribution of the colorant contained in the toner particles can be controlled within the above range. The wet pulverization step can also be applied to the dispersion after the reaction, if necessary. Furthermore, in the case of the examples of the present invention, in order to obtain the high-quality toner, masterbatch colorant particles in which a colorant is dispersed at a high concentration in a resin are added as a colorant material in an organic solvent and stirred and dispersed. The method of making it preferable can be employ | adopted. By using the master batch particles, it is possible to obtain a toner that gives a color image with good transparency in which a colorant having a small dispersed particle diameter is uniformly dispersed.

  In order to preferably produce such masterbatch colorant particles, a mixture of a heat-meltable resin and a colorant is kneaded with a high shearing force at the melting temperature of the resin, and the resulting kneaded product is cooled and solidified. This solidified product is pulverized. As the resin, a thermoplastic resin having good miscibility with the urea-modified polyester resin C derived from the prepolymer A is used. In the case of the Example of this invention, a polyester-type resin is used preferably. In the said thermoplastic resin, the softening point is 100-200 (degreeC), Preferably it is 120-160 (degreeC), The number average molecular weight Mn is 2500-50000, Preferably it is 2500-30000. The colorant concentration in the masterbatch colorant particles is 10 to 60% by weight (%), preferably 25 to 55% (%).

  Next, a method for measuring toner physical properties such as the dispersed particle diameter of the pigment-based colorant in the toner will be described in detail. In order to measure the dispersed particle size and particle size distribution of the colorant in the toner, a measurement sample in which the toner is embedded in an epoxy resin and the toner is ultrathinned to about 100 nm with a microtome MT6000-XL (Keiwa Corporation). Prepare. Using an electron microscope (H-9000NAR manufactured by Hitachi, Ltd.), a plurality of TEM photographs were taken at an acceleration voltage of 100 kV at a magnification of 10,000 to 40000 times, and the image information was obtained with an image processing analyzer LUZEX III of IMAGE ANALYZER. Convert to image data. The target pigment-based colorant particles are repeatedly measured until the sampling exceeds 300 times for particles having a particle size of 0.1 (μm) or more, and the average particle size and particle size (particle size) distribution are determined. Ask.

  In the toner of the example of the present invention, the weight average particle diameter (Dv) is 3 to 7 (μm), and the ratio (Dv / Dn) to the number average particle diameter (Dn) is 1.00 ≦ Dv / Dn ≦ 1.20. By defining Dv / Dn in this way, it is possible to obtain a toner with high resolution and high image quality. In order to obtain a higher quality image, the colorant has a weight average particle diameter (Dv) of 3 to 7 (μm) and a ratio (Dv / Dn) to the number average particle diameter (Dn) of 1.00. ≦ Dv / Dn ≦ 1.20, and the number (%) of particles of 3 (μm) or less is preferably 1 to 10 (%), and more preferably the weight average particle diameter is 3 to 6 ( μm) and Dv / Dn should be 1.00 ≦ Dv / Dn ≦ 1.15. Such a toner is excellent in all of heat-resistant storage stability, low-temperature fixability, and hot offset resistance, and particularly excellent in image gloss when used in a full-color copying machine. Even if the toner balance is extended over a wide range, fluctuations in the particle size of the toner in the developer are reduced, and good and stable developability can be obtained even with long-term stirring in the developing device.

  In general, it is said that the smaller the toner particle size, the more advantageous it is to obtain a high-resolution and high-quality image, but conversely, it is disadvantageous for transferability and cleaning properties. It is. In addition, when the volume average particle diameter of the toner is smaller than the range defined in the embodiment of the present invention, the toner is fused to the surface of the carrier in the two-component developer during long-term stirring in the developing device, and the charging ability of the carrier Reduce. On the other hand, when used as a one-component developer, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur. These phenomena are greatly related to the content of fine powder in the toner. Particularly, when the content of particles of 3 (μm) or less exceeds 10 (%), it is difficult for the toner to adhere to the carrier and the level is high. This makes it difficult to achieve stable charging.

  On the contrary, when the particle diameter of the toner is larger than the range specified in the embodiment of the present invention, it becomes difficult to obtain a high-resolution and high-quality image and the balance of the toner in the developer is performed. In many cases, the variation of the toner particle diameter increases. It was also clarified that the same was true when the weight average particle diameter / number average particle diameter was larger than 1.20.

  The average particle diameter and the particle size distribution of the toner are measured by a car Coulter counter method. Examples of the measuring device for the particle size distribution of toner particles include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). In the examples of the present invention, a Coulter counter TA-II type was used, and an interface for outputting number distribution and volume distribution (manufactured by Nikka Giken) and a PC9801 personal computer (manufactured by NEC) were connected and measured.

  Next, a method for measuring the toner number distribution and volume distribution will be described.

  First, 0.1 to 5 (ml) of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 (ml) of the aqueous electrolytic solution. Here, the electrolytic solution is an approximately 1 (%) NaCl aqueous solution formed using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 (mg) of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles using a 100 (μm) aperture as the aperture. Calculate volume distribution and number distribution.

  As a channel, it is less than 2.00-2.52 (micrometer); 2.52-3.17 (micrometer); 3.17-4.00 (micrometer); 4.00-5.04 (micrometer) Less than 5.04 to 6.35 (μm); 6.35 to less than 8.00 (μm); 8.00 to less than 10.08 (μm); 10.08 to less than 12.70 (μm); 12.70 to less than 16.00 (μm); 16.00 to less than 20.20 (μm); 20.20 to less than 25.40 (μm); 25.40 to less than 32.00 (μm); Using 13 channels of 00 to less than 40.30 (μm), particles having a particle size of 2.00 (μm) or more to less than 40.30 (μm) are targeted. The ratio Dv / Dn was determined from the volume-based weight average particle diameter (Dv) determined from the volume distribution related to the toner of the example of the present invention and the number average particle diameter (Dn) determined from the number distribution.

  Regarding the hot offset resistance of the toner, various studies have been conducted so far including control of the molecular weight distribution of the binder resin. As a method for achieving both conflicting properties such as low temperature fixability and hot offset resistance, a method using a binder resin having a wide molecular weight distribution, a high molecular weight component having a molecular weight of several hundred thousand to several million, and a molecular weight There is a method using a mixed resin having at least two molecular weight peaks including several thousand to several tens of thousands of low molecular weight components. When the high molecular weight component has a crosslinked structure or is in a gel state, it is more effective for hot offset. However, in a full-color toner that requires glossiness and transparency, it is not preferable to introduce a large amount of a high molecular weight component. In the embodiment of the present invention, since the toner contains a high molecular weight urea-modified polyester resin having a urea bond, it is possible to achieve hot offset resistance while satisfying transparency and gloss. It was.

  The molecular weight distribution of the binder resin component contained in the toner is measured by GPC as follows. The column was stabilized in a 40 (° C.) heat chamber, and THF was flowed as a column solvent at this temperature at a flow rate of 1 (ml) per minute, and the sample concentration was adjusted to 0.05 to 0.6 weight (%). Measurement operation is performed by injecting 50 to 200 μl of a THF sample solution of the resin. In measuring the molecular weight of the sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, Pressure Chemical Co. Alternatively, the molecular weights of Toyo Soda Kogyo Co., Ltd. are 6 × 102, 2.1 × 102, 4 × 102, 1.75 × 104, 1.1 × 105, 3.9 × 105, 8.6 × 105, 2 × 106. 4.48 × 10 6 are used, and at least about 10 standard polystyrene samples are used. An RI (refractive index) detector is used as the detector.

  The main peak molecular weight in the molecular weight distribution of the binder component contained in the toner is usually 2500 to 10,000, preferably 2500 to 8000, and more preferably 2500 to 6000. When the amount of the component having a molecular weight of less than 1000 increases, the heat resistant storage stability tends to deteriorate. On the other hand, when the component having a molecular weight of 30000 or more increases, the low-temperature fixability tends to decrease. However, the decrease can be suppressed as much as possible by balance control. The content of components having a molecular weight of 30000 or more is 1 (%) to 10 (%), and varies depending on the toner material, but is preferably 3 to 6 (%). If it is less than 1 (%), sufficient hot offset resistance cannot be obtained, and if it exceeds 10 (%), glossiness and transparency are deteriorated. The Mn of the binder resin contained in the toner is 2500 to 50000, and the value of Mw / Mn is 10 or less. When it exceeds 10, sharp melt property is lacking and glossiness is impaired.

  The circularity of the toner according to the embodiment of the present invention is measured by a flow type particle image analyzer FPIA-2000 (manufactured by Sysmex Corporation). The toner according to the embodiment of the present invention has an average circularity of 0.900 to 0.960, and it is important to have a specific shape and shape distribution. When the average circularity is less than 0.900, the toner exhibits an irregular shape and does not give satisfactory transferability and high-quality images without dust. Since the irregularly shaped toner particles have many contact points with the smooth medium on the photosensitive member and the charge concentrates on the tip of the protrusion, the van der Waals force and the mirror image force are higher than those of the relatively spherical particles. Therefore, in the electrostatic transfer process, the spherical particles are selectively moved in the toner in which the amorphous particles and the spherical particles are mixed, and the character portion and the line portion image are lost. In addition, the remaining toner must be removed for the next development process, and there is a problem that a cleaner device is required or the toner yield (the ratio of toner used for image formation) is low. . The circularity of the pulverized toner is usually 0.910 to 0.920 when measured with this apparatus.

  As a method for measuring the toner shape (circularity), an optical detection zone method is used in which a suspension containing particles is passed through an imaging zone detection zone on a flat plate, and a particle image is optically detected and analyzed by a CCD camera. Is appropriate. In this method, the projected area of the particle can be obtained. The circularity is a value obtained by dividing the circumference of an equivalent circle having the same area as the projected area by the circumference of the actual particle. This value is a value measured as an average circularity by a flow type particle image analyzer FPIA-2000. As a specific measuring method, a surfactant, preferably an alkylbenzene sulfonate, is added in an amount of 0.1 to 0.5 (as a dispersant) in 100 to 150 (ml) of water from which impure solids have been previously removed. ml) and about 0.1 to 0.5 g of a measurement sample is further added. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the concentration of the dispersion is set to 3000 to 10,000 / μl, and the shape of the toner and the shape distribution of the toner are measured by the apparatus.

  A method for producing a toner according to an embodiment of the present invention includes a high molecular weight process in which an isocyanate group-containing polyester prepolymer A dispersed in an aqueous medium containing inorganic fine particles and / or fine polymer particles is reacted with an amine B. . In this case, the polyester-based prepolymer (A) containing an isocyanate group is a polycondensate of a polyol (PO) and a polycarboxylic acid (PC), and a polyester having an active hydrogen group is further reacted with the polyisocyanate (PIC). Can be obtained. In this case, examples of the active hydrogen group of the polyester include a hydroxyl group (alcoholic hydroxyl group and phenolic hydroxyl group), an amino group, a carboxyl group, a mercapto group, and the like. Among these, an alcoholic hydroxyl group is preferable.

  Examples of the polyol (PO) include diol (DIO) and trivalent or higher polyol (TO), and (DIO) alone or a mixture of (DIO) and a small amount of (TO) is preferable. Diol (DIO) includes alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol, triethylene glycol, Ethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol F, Bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide phenol compound (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. Examples of the trivalent or higher polyol (TO) include 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trivalent or higher phenols (Tris) Phenol PA, phenol novolak, cresol novolak, etc.); alkylene oxide adducts of the above trivalent or more polyphenols.

  Examples of the polycarboxylic acid (PC) include dicarboxylic acid (DIO) and trivalent or higher polycarboxylic acid (TC), and (DIO) alone and a mixture of (DIO) and a small amount of (TC) are preferable. Dicarboxylic acids (DIO) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, naphthalene) Dicarboxylic acid and the like). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polycarboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polycarboxylic acid (PC), you may make it react with a polyol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyol (PO) and the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably 1 as the equivalent ratio (OH) / (COOH) of the hydroxyl group (OH) to the carboxyl group (COOH). 5/1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  Examples of the polyisocyanate (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; the polyisocyanates as phenol derivatives, oximes, caprolactams And a combination of two or more of these.

  When obtaining a polyester-based prepolymer having an isocyanate group, the ratio of the polyisocyanate (PIC) and the polyester-based resin (PE) having active hydrogen is such that the isocyanate group (NCO) and the hydroxyl group (OH) of the polyester having a hydroxyl group are The equivalent ratio (NCO) / (OH) is usually 5/1 to 1/1, preferably 4/1 to 1.2 / 1, and more preferably 2.5 / 1 to 1.5 / 1. When (NCO) / (OH) exceeds 5, the low-temperature fixability deteriorates. When the molar ratio of (NCO) is less than 1, when a modified polyester is used, the urea content in the ester becomes low and the hot offset resistance deteriorates. The content of the polyisocyanate (PIC) component in the prepolymer (A) having an isocyanate group at the terminal is usually 0.5 to 40% by weight, preferably 1 to 30% by weight, more preferably 2 -20% by weight. If it is less than 0.5 weight (%), the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40% by weight, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester-based prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the resulting urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  As the amine (B), a polyamine and / or a monoamine having an active hydrogen-containing group is used. In this case, the active hydrogen-containing group includes a hydroxyl group and a mercapto group. Such amines include diamine (B1), tri- or higher polyamine (B2), aminoalcohol (B3), aminomercaptan (B4), amino acid (B5), and amino acids B1-B5 blocked ( B6) and the like. Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, Isophorone diamine etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazoline compounds obtained from the B1 to B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  Furthermore, when the prepolymer A and the amine B are reacted, the molecular weight of the polyester can be adjusted by using an elongation terminator if necessary. Examples of the elongation terminator include monoamines having no active hydrogen-containing groups (diethylamine, dibutylamine, butylamine, laurylamine, and the like), and those blocked (ketimine compounds). The addition amount is appropriately selected in relation to the molecular weight desired for the urea-modified polyester to be produced.

  The ratio of the amine (B) to the prepolymer (A) having an isocyanate group is determined by the isocyanate group (NCO) in the prepolymer (A) having an isocyanate group and the amino group (NHx) (x in the amine (B)). Is an equivalent ratio (NCO) / (NHx) of usually 1 to 2, usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2. /1-1/1.2. When (NCO) / (NHx) exceeds 2 or less than 1/2, the molecular weight of the polyester becomes low, and the hot offset resistance deteriorates.

  In the examples of the present invention, when the isocyanate group-containing prepolymer A and the amine B are reacted in the aqueous medium, the amine-reactive polyester resin D is added to the aqueous medium as necessary. Can exist. In this polyester resin D, its Tg is 35 to 65 (° C.), preferably 45 to 60 (° C.), and its Mn is 2000 to 10000, preferably 2500 to 8000. As this polyester resin D, urea-modified polyester (UMPE) can be used, but this polyester may contain a urethane bond as well as a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10 (%), the hot offset resistance is deteriorated. Urea-modified polyester (UMPE) is produced by a known method such as a one-shot method. The weight average molecular weight of the urea modified polyester (UMPE) is usually 10,000 or more, preferably 20,000 to 500,000, and more preferably 30,000 to 100,000. If it is less than 10,000, the hot offset resistance deteriorates.

  In the embodiments of the present invention, the polyester resin (UMPE) modified with a urea bond used as necessary is not only used alone, but also with this, an unmodified polyester resin (PE) is used as a toner binder. It can also be contained as a component. The combined use of (PE) improves the low-temperature fixability and the gloss when used in a full-color device, and is more preferable than the case of using (UMPE) alone. Examples of (PE) include polycondensates of polyol (PO) and polycarboxylic acid (PC) similar to the polyester component of (UMPE), and the preferred molecular weight of PE is the same as that of (UMPE). is there. (PE) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, for example, may be modified with a urethane bond. (UMPE) and (PE) are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, the polyester component of (UMPE) and (PE) preferably have similar compositions. When (PE) is contained, the weight ratio of (UMPE) to (PE) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75, Particularly preferred is 7/93 to 20/80. When the weight ratio of (UMPE) is less than 5 (%), the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The hydroxyl value of (PE) is preferably 5 or more. The acid value ((mg) KOH / g) of (PE) is usually 1 to 30, preferably 5 to 20. By giving the acid value, it tends to be negatively charged, and further, the affinity between the paper and the toner when fixing to paper is good, and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly the environmental fluctuation. In the polyaddition reaction between the prepolymer A and the amine B, if the acid value is touched, it will lead to shaking in the granulation step, making control in emulsification difficult.

  In the embodiment of the present invention, the glass transition point (Tg) of the toner binder is usually 45 to 65 (° C.), preferably 45 to 60 (° C.). If it is less than 45 (° C.), the heat resistance deteriorates, and if it exceeds 65 (° C.), the low-temperature fixability becomes insufficient.

On the other hand, the fixing device 1 uses a configuration in which the fixing member is heated by an electromagnetic induction heating method having the configuration shown in FIG.
In FIG. 3, the fixing device 1 includes a fixing roller 101 and a pressure roller 102 that face each other across the conveyance path of the recording sheet A, and a heating roller 103, a fixing roller 101, and a heating roller disposed in the vicinity of the fixing roller 101. 103, and a fixing belt 104 wound around 103 and an electromagnetic induction heating means 105.

The fixing roller 101 includes a metal core 101A made of, for example, stainless steel, and an elastic member 101B having a heat-resistant silicone rubber coated in a solid or foamed state and covered on the surface of the core metal 101A.
The fixing roller 101 can be compressed and deformed along the peripheral surface of the pressure roller 102 by a pressing force from the pressure roller 102, and a contact portion (fixing nip portion) N having a predetermined width can be formed in the compression deformed portion. It is like that. In this embodiment, in order to form the contact portion (nip portion) N, the outer diameter of the fixing roller 101 is set to about φ30 (mm) and is larger than the heating roller 103 described later.
The elastic member 101B is set to have a thickness of about 5 mm and a hardness of about 50 ° (Asker hardness).

  The pressure roller 102 is provided on a surface of the core metal 102A and a core metal 102A made of a metal cylindrical member having a high thermal conductivity such as copper or aluminum and having a thickness of about 0.8 mm to 1 mm. The elastic member 102B has high heat resistance and high toner releasability. In addition to the above metal, SUS may be used for the core metal 102A.

The pressure roller 102 forms the fixing nip portion N by pressing the fixing roller 101 via the fixing belt 104. In this embodiment, the pressure roller 102 is harder than the fixing roller 101. By doing so, the pressure roller 102 can bite into the fixing roller 101 (and the fixing belt 104), and the recording sheet S can follow the circumferential shape of the surface of the pressure roller 102 by this biting. For this reason, when the recording sheet S moves along the circumferential surface of the pressure roller 102 and leaves the circumferential surface, the circumferential curvature of the pressure roller 102 increases with respect to the traveling direction of the recording sheet S. Thus, the effect of facilitating separation from the surface of the fixing belt 104 is obtained.
The outer diameter of the pressure roller 102 is about φ30 (mm), which is the same as that of the fixing roller 101, but the thickness is about 1 mm, which is thinner than the fixing roller 101, and the hardness is about 20 to 30 ° (JIS-A hardness). As described above, it is harder than the fixing roller 101.

  The heating roller 103 is made of a hollow cylindrical magnetic metal member made of, for example, iron, SUS, cobalt, nickel, or an alloy of these metals, and has an outer diameter of, for example, φ20 (mm) and a thickness of, for example, 0.1 mm. It is set, and the temperature rises quickly with a low heat capacity.

  The fixing belt 104 wound around the fixing roller 101 and the heating roller 103 is heated in the range of the contact portion W1 with respect to the heating roller 103 heated by the electromagnetic induction heating means 105, and the fixing roller 101 and the pressure roller 102 are heated. The inner surface is continuously heated with the rotation, and as a result, the entire belt is heated.

The base material of the fixing belt 104 is made of a metal material such as nickel having a thickness of about 30 μm so as to function as a heat generating layer, and the thickness of the release layer provided on the surface thereof is 0.2 μm to About 0.5 μm is desirable, and in particular, about 0.3 μm is set as a desirable value.
By using such a configuration, the toner image T formed on the recording sheet S is sufficiently wrapped by the surface layer portion of the fixing belt 104, and the toner image T can be uniformly heated and melted. . As a base material for the fixing belt 104, instead of using a base material as a heat generating layer made of the above metal, heat resistance such as fluorine resin, polyimide resin, polyamide resin, polyamideimide resin, PEEK resin, PES resin, PPS resin, etc. A resin layer having properties may be used.

  In FIG. 3, the electromagnetic induction heating means 105 has a configuration (see FIG. 3A) in which a built-in excitation coil (indicated by reference numeral 105A for convenience) shown in Patent Document 1 is positioned outside the roller. Specifically, it is arranged in a state of being opposed to a part of the peripheral surface of the heating roller 103, and the exciting coil 105A is mounted on a coil guide plate 105B having the same function as the bobbin in Patent Document 1. ing.

  As shown in FIGS. 3B and 3C, the exciting coil 105A is obtained by alternately winding a long exciting coil wire in the axial direction of the heating roller 103 along the surface of the coil guide plate 105B. is there. The exciting coil 105A is connected to a driving power source (not shown) whose oscillation circuit has a variable frequency.

  The excitation coil 105A is fed with a high frequency alternating current of 10 kHz to 1 MHz, preferably a high frequency alternating current of 10 kHz to 800 kHz from the driving power source, thereby generating an alternating magnetic field. In this embodiment, a high frequency alternating current of 10 to 30 kHz is used. This alternating magnetic field acts on the heating roller 103 and the heat generating layer 104A of the fixing belt 104 in the contact area W1 between the heating roller 103 and the fixing belt 104 and in the vicinity thereof, and eddy currents in such a direction as to prevent the change of the alternating magnetic field. Flows. This eddy current generates Joule heat according to the resistance of the heating roller 103 and the base material that is the heat generation layer, and the base material of the fixing belt 104 is mainly in the contact area between the heating roller 103 and the fixing belt 104 and in the vicinity thereof. The exothermic layer is heated.

  The fixing belt 104 has its belt inner surface temperature detected by temperature detecting means 106 comprising a thermosensitive element such as a thermistor disposed in contact with its inner surface in the vicinity of the entrance of the fixing nip N. Temperature control is performed.

The fixing device 1 having such a configuration is provided with a structure for shielding leakage of magnetic flux from the electromagnetic induction heating means 105 to the outside by absorption or attenuation of the magnetic flux. Hereinafter, the magnetic flux shielding structure will be described.
FIG. 4 is a diagram showing a first embodiment related to the magnetic flux shielding structure. As the magnetic flux shielding structure shown in FIG. 4, the casing 200 itself constituting the fixing device 1 can absorb or attenuate the magnetic flux. It is composed of materials. That is, the fixing roller 101, the pressure roller 102, the heating roller 103, the fixing belt 104, and the electromagnetic induction heating means 105, which are fixing members used in the fixing process, are gathered inside the casing 200 formed of an iron-based material. The roller group is rotatably supported by the housing 200. In FIG. 4, reference numeral 105A denotes an exciting coil, reference numeral 105B denotes a coil guide plate, reference numeral 105C denotes an exciting coil core, and reference numeral 105D denotes an exciting coil core support member that supports the exciting coil 105A via the exciting coil core 105C. As the exciting coil core 105C, a ferromagnetic material such as ferrite having a relative magnetic permeability 2500 is used. In the figure, reference numerals 210 and 211 denote a cleaning roller for the fixing belt 104 and a member for applying a cleaning agent to the fixing belt 104, and are provided to remove toner and foreign matters adhering to the fixing belt 104. However, it is possible to adopt a configuration that does not necessarily require these members. Reference numeral 237 denotes a handle of the fixing device 1.
Further, reference numerals 220 and 221 denote supports that independently support the fixing roller 101 and the pressure roller 102. These supports 220 and 221 are connected to the fixing roller 101 and the fixing roller 101 via an elastic body such as a spring (not shown). The pressure roller 102 is urged by a pressure contact force of 10 kgf or more in a direction in which the pressure rollers 102 are brought close to each other. By urging the fixing roller 101 and the pressure roller 102 toward each other, the fixing belt 104 can be sandwiched between the two rollers to form the fixing nip N.

The casing 200 is made of a variable magnetic field shielding material made of a material obtained by mixing metal powder or metal compound and resin, and has a function of shielding a magnetic field from the inside of the fixing device.
Resin such as polyethylene terephthalate (PET) having heat resistance or heat insulation for copper powder, silver powder, copper silver alloy powder or metal oxide powder is used as a material mixed with metal powder or metal compound and resin. It is possible to use a structure such as mixing or lamination at the time of molding. By using a material in which such a metal powder or metal compound and a resin are mixed, heat conduction is suppressed as compared with the case where the entire housing is made of metal. As a result, an abnormal temperature rise in the housing 200 can be suppressed and a thermal adverse effect on the peripheral portion can be prevented, and, for example, the housing 200 can be opened even when the inside of the fixing device is opened to eliminate a jam. It is possible to keep the surface temperature of the glass from increasing. In addition, it is possible to brush the surface of the housing 200 on the assumption that there is an opportunity for human hands to touch the outer surface of the housing 200 so that the hand does not touch the housing surface directly. .

  The casing 200 is provided with openings 200A on the entrance side and the exit side through which a recording medium such as the recording sheet S passes, and the opening 200A is the minimum necessary to allow the recording sheet S to pass. It is provided in size. Difference guide members 200A1 and 200A2 for introducing and discharging the recording sheet S are provided in the vicinity of the opening 200A.

  Since the present embodiment is configured as described above, when a part of the magnetic flux generated from the electromagnetic heating means 105 used as one of the fixing members reaches the casing 200, it is absorbed by the casing 200. (The state indicated by the arrow F in FIG. 4). Thereby, even if it leaks to the outside from the opening 200A, the magnetic flux is smaller than that when it reaches the housing 200 (the state indicated by the arrow F ′ in FIG. 4), and adverse effects on the peripheral portion are suppressed. It will be possible.

Next, a second embodiment relating to the magnetic flux shielding structure will be described with reference to FIG.
This embodiment is characterized in that a casing 201 surrounding the casing of the fixing device 1 (indicated by reference numeral 200 'for convenience) is provided, and this casing 201 is used as a magnetic flux shielding member.
In FIG. 5, a casing 200 ′ capable of supporting each fixing member provided in the fixing device 1 is surrounded by a casing 202, and the casing 201 is similar to the casing 200 ′ in the recording sheet S. An opening 201A is formed in the passage portion.

  As in the case of the housing 200 shown in FIG. 4, the casing 201 is not only made of a ferrous material, but may be made of a conductive non-ferrous material.

  Since the present embodiment is configured as described above, it reaches the casing 201 when a part of the magnetic flux generated from the electromagnetic heating means 105 passes through the casing 200 '. When the casing 201 is an iron-based material, leakage to the outside is suppressed by being absorbed.

  On the other hand, when a conductive non-ferrous material is used, for example, when aluminum is used, the magnetic flux penetrating due to the eddy current generated in the casing by the magnetic flux that is not absorbed by the casing 201 and is about to penetrate. When the magnetic flux is generated in the direction opposite to the direction of the magnetic flux, the magnetic flux to be penetrated is attenuated.

  In the present embodiment, when the fixing device 1 is set to a temperature necessary for fixing, it is safer that the hands 200 'of the fixing device 1 having a relatively high temperature are not touched directly. In addition, the casing 201 functions as a heat dissipating part to prevent the ambient temperature in the peripheral part of the fixing device 1 from rising.

Next, a modification of the main part of the embodiment shown in FIGS. 4 and 5 will be described.
FIG. 6 is a diagram for the embodiment shown in FIG. 4, and in the configuration shown in FIG. 6, a cover member 202 is provided in an opening that allows the recording sheet S to pass therethrough.
The cover member 202 has flexibility, and is formed of, for example, a film member such as a thin piece of aluminum shown in FIG. 5 or a tape sprayed with iron powder.

  The cover member 202 is normally provided in a state where the opening 200A is closed by utilizing flexibility (a state indicated by a solid line in the drawing), and when the cover member 202 is pushed and moved by the recording sheet S, the opening 200A can be opened. It can be (state shown with a dashed-two dotted line in a figure), and is provided in the housing | casing 200 with the attachment structure. In order to release the recording sheet S by pushing it, a cantilever-like configuration is used in which the end on the side pushed by the recording sheet S is a swing end, as shown in FIG. Is also possible.

  When the cover member 202 is provided on each of the entrance side and the exit side of the recording sheet S with respect to the casing 200, the shielding efficiency of the leakage magnetic flux from the opening 200A is improved. In terms of contact, at least on the exit side, on the entrance side, a condition that does not cause disturbance of the toner image due to rubbing when contacting the toner image, i.e., a material with less toner adhesion or a bending rigidity You may make it use.

  In this configuration, since the cover member 202 is provided in the opening 200 </ b> A which is a magnetic flux leakage portion, the magnetic flux can be effectively prevented from leaking to the outside.

Next, a third embodiment relating to the magnetic flux shielding structure will be described.
The present embodiment is characterized in that a heat radiating portion is provided in a member constituting a pseudo closed space for shielding magnetic flux.
7 is a diagram illustrating only the fixing device 1 including the housing 200 illustrated in FIG. 4. FIG. 7A is an external view of the fixing unit, and FIG. 7B is a fixing unit. It is a schematic diagram of the Example which made object.
In FIG. 7, the housing 200 is provided with a heat radiating opening 200 </ b> B capable of communicating between the inside and the outside, in addition to the opening 200 </ b> A that is a passage portion of the recording sheet S. The heat radiating opening 200B is provided in a direction perpendicular to the opening 200A forming the passing portion of the recording sheet S, in other words, on the wall surface positioned at the end portion in the axial direction of each roller.
Regarding the heat radiation opening, in the configuration shown in FIG. 5, not only the casing 200 but also the casing 201 can be provided, and the heat radiation opening is formed at the same position on the opposing wall surfaces.

  The heat radiation opening 200B shown in FIG. 7 is provided in a single direction on the wall surface located at the axial end of each roller in a direction orthogonal to the opening 200A forming the passage portion of the recording sheet S, in other words, fixing. Hot air can be discharged from the inside of the apparatus 1 to the outside, or external cold air can be made to enter the inside.

  The circulation of the inside and outside air through the heat radiation opening 200B can use, for example, an air flow by a cooling fan provided in the image forming apparatus.

  In the present embodiment, the fixing device 1 whose inside is close to the closed space by the casing 200 can prevent the fixing device 1 from being overheated, such as hot offset that is likely to occur due to the overheating state. Can be prevented.

Next, another embodiment related to heat dissipation will be described.
FIG. 8 shows a state in which a plurality of heat radiation openings (indicated by reference numeral 200B ′ for convenience) are provided, and the heat radiation openings 200B ′ are formed by lath hole processing.

  The heat radiating openings 200B 'shown in FIG. 8 have the same heat radiating area as the single heat radiating openings 200B shown in FIG. That is, since the heat radiation openings 200B and 200B 'are portions that communicate with the inside and outside of the fixing device 1, it is necessary to consider leakage of magnetic flux from these portions. For this reason, since the size is determined based on the fact that leakage is most likely in the case of a single opening, this idea is also assumed when a plurality of heat radiation openings 200B are provided.

  In this embodiment, by providing a plurality of heat radiating openings 200B ′, heating inside the fixing device 1 can be suppressed and a plurality of heat radiating openings 200B ′ can be formed. It becomes possible. In other words, the heat radiation unevenness can be hardly caused by forming the entire wall surface in a distributed manner. In addition, by reducing the size of the plurality of heat radiation openings 200B 'provided, it is possible to reduce the portion where the magnetic flux leaks to the outside and to easily suppress the leakage of the magnetic flux.

Next, another embodiment relating to heat dissipation will be described.
The present embodiment is characterized in that a configuration for absorbing or attenuating leakage magnetic flux is provided in an opening for heat dissipation.
FIG. 9 is a view showing the heat radiation opening 200B shown in FIG. 7 for the purpose of explaining the present embodiment.

  In FIG. 9, a metal mesh 203 having a ventilation portion that can communicate with the inside and outside of the fixing device 1 is provided in the heat radiation opening 200 </ b> B. The metal mesh 203 is made of the same material as that of the housing 200, and the mesh size thereof is set in consideration of the condition that the leakage magnetic flux can be absorbed or attenuated while having a ventilation area necessary for heat dissipation.

  In the present embodiment, the leakage flux can be shielded while securing a ventilation portion for heat radiation by a simple configuration in which the wire net 203 as a magnetic shield member is provided in the heat radiation opening 200B.

  In each of the embodiments described above, the casing 200 or the casing 201 of the fixing device 1 used as the magnetic flux shielding structure is provided with a cover member that is opened or attached to the passage portion of the recording sheet S and is moved by the recording sheet S. For example, even when a configuration for forcibly opening and closing the opening is used, no special opening / closing means is required. For this reason, for example, it is possible to prevent complication of the configuration as in the case of using a mechanism that opens and closes the shutter using a solenoid or the like, and further, magnetic interference does not occur as in the case where an electromagnetic member such as a solenoid is provided. In such a case, it is possible to prevent a situation in which leakage of magnetic flux is promoted.

1 is a schematic diagram illustrating a configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. FIG. 4 is a view for explaining an arrangement state of process cartridges including a fixing device in the image forming apparatus shown in the figure. It is a schematic diagram for demonstrating the heating structure used for the fixing apparatus by the Example of this invention. FIG. 4 is a diagram for explaining a first embodiment of a fixing device targeting the heating structure shown in FIG. 3. It is a figure for demonstrating the 2nd Example regarding the fixing device to this invention. It is a figure for demonstrating the principal part modification in the Example shown in FIG. 4 and FIG. It is a figure for demonstrating the 3rd Example regarding the fixing device of this invention. It is a figure for demonstrating another Example of the principal part shown in FIG. FIG. 8 is a diagram for explaining another example of the main part shown in FIG. 7. It is a figure which shows the prior art example of the fixing device using an electromagnetic induction heating system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing device 20 Image forming device 21 Image forming device 22 Transfer device 101 Fixing roller 102 Pressure roller 103 Heating roller 104 Belt 105 Electromagnetic heating means
200, 200 'casing 200A, 200A' recording medium passage opening 200B, 200B 'heat dissipation opening
201 Casing 202 Cover member 203 Wire mesh

Claims (23)

In a fixing device that performs a fixing process by bringing a fixing member heated using an electromagnetic induction heating method into contact with a visible image,
The fixing member is disposed at a position where the fixing member can be surrounded, and has a structure for attenuating or shielding a magnetic flux generated from the electromagnetic induction heating member in a state where a recording medium passing portion is provided in contact with the fixing member. Fixing device to do. The fixing device according to claim 1.
A fixing device characterized in that, as the magnetic flux shielding structure, a housing for housing the fixing member is made of a material that can absorb magnetic force or attenuate magnetic force. The fixing device according to claim 1.
A fixing device comprising a casing surrounding the periphery of a housing for accommodating the fixing member as the magnetic flux shielding structure, and the casing is made of a material capable of absorbing magnetic force or attenuating magnetic force. The fixing device according to any one of claims 1 to 3,
A cover member made of a flexible member made of a material that is magnetically absorbable or magnetically damped is provided in the passage portion of the recording medium in the housing or casing, similar to the housing or casing. The fixing device is characterized in that the member can open the passage portion by passage of a recording medium. The fixing device according to any one of claims 1 to 4, wherein:
A fixing device using an iron-based material as a material for the magnetic flux shielding structure. The fixing device according to any one of claims 1 to 4, wherein:
A fixing device using a conductive non-ferrous material as a material used for the magnetic flux shielding structure. The fixing device according to any one of claims 1 to 6, wherein:
The fixing device according to claim 1, wherein the casing or casing used for the shielding structure is provided with a heat radiating portion. The fixing device according to any one of claims 1 to 6, wherein:
A fixing device, wherein a casing or casing used for the shielding structure uses a variable magnetic field shielding material configured by mixing a metal powder or a metal compound and a resin. The fixing device according to claim 8.
The fixing device according to claim 1, wherein the heat radiating portion is configured by an opening that allows communication between the inside and the outside of the housing or the casing. The fixing device according to claim 9.
The fixing device according to claim 1, wherein the opening is single or plural. The fixing device according to claim 9 or 10, wherein:
A fixing device, wherein when a single opening is provided, a wire mesh having a ventilation portion is disposed in the opening. The fixing device according to claim 10.
The fixing device is characterized in that the opening has the same heat radiation area in either case of single or plural.   An image forming apparatus using the fixing device according to claim 1. The image forming apparatus according to claim 13.
The recording medium conveyed to the fixing device is disposed on a recording medium discharge path in a process cartridge in which a latent image carrier, a developing device, and a latent image carrier cleaning device are accommodated together. An image forming apparatus. The image forming apparatus according to claim 14.
A prepolymer made of a modified polyester resin in an organic solvent as a developer used for visible image processing of an electrostatic latent image formed on the latent image carrier used in the developing device, and the prepolymer It is obtained by dissolving or dispersing the compound that stretches or crosslinks with the toner and the toner composition, crosslinks and / or stretches the dissolved or dispersed material in an aqueous medium, and removes the solvent from the obtained dispersion. An image forming apparatus using the polymerized toner. The image forming apparatus according to claim 14 or 15,
As the polymerized toner, the dispersed particle diameter of the pigment colorant dispersed in the polymerized toner is a number average diameter of 0.5 (μm) or less, and the number average diameter is 0.7 (μm) or more. An image forming apparatus having a ratio of 5 or less (%). The image forming apparatus according to claim 14, wherein
The colorant as a constituent component of the polymerized toner is characterized in that a dispersed particle diameter is 0.3 (μm) or less in number average diameter and the number average diameter is 10 (%) or less. Image forming apparatus. The image forming apparatus according to any one of claims 14 to 17, wherein
The polymerized toner has a weight average particle size of 3.0 (μm) or more and 7.0 (μm) or less, and a particle size distribution of 1.00 ≦ Dv / Dn ≦ 1.20 (Dv: weight average). An image forming apparatus having a particle diameter, Dn: number average particle diameter). The image forming apparatus according to any one of claims 14 to 18, wherein:
An image forming apparatus, wherein the circularity of the polymerized toner is 0.900 or more and 0.960 or less. The image forming apparatus according to claim 14, wherein:
In the molecular weight distribution of the tetrahydrofuran-soluble component of the polyester resin contained in the polymerized toner, a main peak exists in the region of the molecular weight of 2500 to 10,000, and the number average molecular weight is in the range of 2500 to 50,000. Image forming apparatus. 21. The image forming apparatus according to claim 14, wherein:
An image forming apparatus, wherein the polyester resin contained in the polymerized toner has a glass transition point of 40 to 65 (° C.) and an acid value of 1 to 30 (mgKOH / g). The image forming apparatus according to any one of claims 14 to 21, wherein:
An image forming apparatus, wherein the oily dispersion of the polymerized toner dissolves a polyester-based resin that is non-reactive with the amine. 23. The image forming apparatus according to claim 14, wherein:
An image forming apparatus using a developer containing the polymerized toner and a carrier.

Images