JP2009288746A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus and an image forming apparatus, of an electromagnetic induction heating type, capable of preventing generation of an image with wax on a printed recording medium even in the case where toner containing paraffin wax having a melting point of 60 to 90°C is used. <P>SOLUTION: There is provided an induction heating part which faces an outer-peripheral surface of a fixing member and directly or indirectly heating the fixing member by means of electromagnetic induction. The toner contains paraffin wax having a melting point of 60 to 90°C. During any other process than the fixing process, the induction heating part is energized and heated to execute a cleaning mode for removing paraffin wax to be fixed to the induction heating part for a predetermined period (step S5). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine thereof, and a fixing device installed therein, and more particularly, an electromagnetic for fixing a toner containing paraffin wax on a recording medium. The present invention relates to an induction heating type fixing device and an image forming apparatus.

Conventionally, in an image forming apparatus such as a copying machine or a printer, an electromagnetic induction heating type fixing device is known (for example, see Patent Document 1).
Specifically, the electromagnetic induction heating type fixing device includes a fixing member such as a fixing roller and a fixing belt, a pressure member that presses against the fixing member to form a nip portion, and electromagnetically fixes the fixing member facing the outer peripheral surface of the fixing member. An induction heating unit for induction heating is used. The induction heating unit includes an exciting coil, a core that covers the exciting coil, a coil guide that holds the exciting coil and faces the fixing member, and the like. When the exciting coil of the induction heating unit is energized, a magnetic flux is formed around the heat generating layer of the fixing member (or the heat generating layer of the heating member in contact with the fixing member), and the heat generating layer is electromagnetically heated, The fixing member is heated directly (or indirectly). Thus, the toner on the recording medium that contacts the fixing member at the position of the nip is heated and melted, and the toner is fixed on the recording medium.
Here, in order to improve the heating efficiency of the fixing member, the induction heating unit (coil guide) is disposed so as to face the fixing member with a small gap.

  On the other hand, Patent Document 2, Patent Document 3 and the like improve low-temperature fixability and improve the separation property (release property) of the recording medium with respect to the fixing member and the pressure member without applying oil to the fixing member. For this purpose, a technique for incorporating a paraffin wax having a melting point in the range of 60 to 90 ° C. into a toner used in an image forming process is disclosed.

  On the other hand, Patent Document 4 and the like disclose a technique of cleaning a wax filmed on a fixing belt by reversely rotating a pressure roller that is in pressure contact with the fixing belt, which is a fixing device of a heater type. Yes.

JP 2008-40176 A JP 2008-76565 A JP 2008-97046 A JP 2007-52296 A

  The above-described conventional electromagnetic induction heating type fixing device is intended to improve the low-temperature fixing property and to improve the separation property (release property) of the recording medium with respect to the fixing member and the pressure member without applying oil to the fixing member. When a toner containing paraffin wax having a melting point in the range of 60 to 90 ° C. is used, the induction heating unit (coil) in which the paraffin wax volatilized at the position of the nip or the surface of the fixing member is opposed to the fixing member. There was a problem that the paraffin wax adhered to the opposing surface of the guide) was fixed. When the amount of paraffin wax that adheres to and accumulates on the opposite surface of the induction heating unit (coil guide) increases and the accumulated height exceeds a minute gap with the fixing member, the induction heating unit A part of the paraffin wax adhered to the fixing member adheres to the fixing member. Then, the paraffin wax adhering to the fixing member adheres to the recording medium at the position of the nip portion during the fixing process (the image on the recording medium to which the wax adheres in this way is referred to as “wax adhesion image”). .

  The present invention has been made to solve the above-described problems, and is a recording medium that is printed out even when a toner containing paraffin wax having a melting point in the range of 60 to 90 ° C. is used. An object of the present invention is to provide an electromagnetic induction heating type fixing device and an image forming apparatus in which no “wax adhesion image” is generated.

  A fixing device according to a first aspect of the present invention is a fixing device that performs a fixing step of fixing toner onto a recording medium conveyed to a nip portion, and forms the nip portion together with a pressure member. A fixing member that heats and melts the toner while traveling in a predetermined direction, and an induction heating unit that opposes the outer peripheral surface of the fixing member and that directly or indirectly heats the fixing member by electromagnetic induction. The toner contains a paraffin wax having a melting point in the range of 60 to 90 ° C., and the paraffin is fixed to the induction heating unit by energizing and heating the induction heating unit except when the fixing step is performed. A cleaning mode for removing the wax is performed for a predetermined time.

  According to a second aspect of the present invention, in the fixing device according to the first aspect of the present invention, the cleaning mode energizes and heats the induction heating unit and travels the fixing member.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the cleaning mode is performed at regular intervals.

  According to a fourth aspect of the present invention, in the fixing device according to the third aspect, the interval for performing the cleaning mode is variable.

  According to a fifth aspect of the invention, in the fixing device according to the third or fourth aspect, the interval for performing the cleaning mode is determined by the number of recording media conveyed to the nip portion. It is what

  According to a sixth aspect of the present invention, in the fixing device according to the third or fourth aspect, the interval for performing the cleaning mode is determined by a travel distance or a travel time of the fixing member. It is.

  According to a seventh aspect of the present invention, in the fixing device according to the third or fourth aspect, the interval for performing the cleaning mode is determined by a consumption amount of the toner.

  The fixing device according to an eighth aspect of the present invention is the fixing device according to any one of the first to seventh aspects, wherein the cleaning mode includes an opposing surface of the induction heating unit facing the fixing member. The induction heating unit is energized and heated so that the heating temperature with its vicinity is equal to or higher than the melting point of the paraffin wax.

  According to a ninth aspect of the present invention, in the fixing device according to the eighth aspect, the heating temperature in the cleaning mode is variable.

  A fixing device according to a tenth aspect of the present invention is the fixing device according to any one of the first to ninth aspects, wherein the energization time of the induction heating unit in the cleaning mode is 20 seconds or more. is there.

  The fixing device according to an eleventh aspect of the present invention is the fixing device according to the tenth aspect, wherein the energization time in the cleaning mode is variable.

  The fixing device according to a twelfth aspect of the present invention is the fixing device according to any one of the first to eleventh aspects, wherein the cleaning mode energizes and heats the induction heating unit and the fixing member. The running speed of the fixing member is set to 50 mm / second or more and less than the maximum linear speed of the apparatus.

  According to a thirteenth aspect of the present invention, in the fixing device according to the twelfth aspect, the traveling speed of the fixing member in the cleaning mode is variable.

  According to a fifteenth aspect of the present invention, in the fixing device according to any one of the first to thirteenth aspects, the cleaning mode is forcibly executed by a serviceman or user operation. It is.

  According to a fifteenth aspect of the present invention, there is provided a fixing device according to any one of the first to fourteenth aspects of the present invention, for performing printing with the fixing step when the cleaning mode is performed. When there is a print request, the cleaning mode is interrupted and the print request is preferentially executed.

  According to a sixteenth aspect of the present invention, in the fixing device according to the fifteenth aspect, when the cleaning mode is interrupted, the cleaning mode is newly set after the execution of the print request is completed. It is performed for a predetermined time.

  According to a seventeenth aspect of the present invention, in the fixing device according to the fifteenth aspect, when the cleaning mode is interrupted, an integrated time before and after the cleaning mode is interrupted matches the predetermined time. As described above, the cleaning mode is performed after the execution of the print request is completed.

  A fixing device according to an eighteenth aspect of the present invention is the fixing device according to any one of the first to seventeenth aspects, wherein the printing with the fixing step is performed for a time equal to or longer than the predetermined time. The cleaning mode is performed after the printing is completed.

  According to a nineteenth aspect of the present invention, in the fixing device according to any one of the first to eighteenth aspects, the energy saving mode or the power-off mode is performed when the cleaning mode is performed. When there is a request, the cleaning mode is preferentially executed, and the request is executed after the cleaning mode ends.

  An image forming apparatus according to a twentieth aspect of the present invention includes the fixing device according to any one of the first to nineteenth aspects.

  In the present invention, the melting point is in the range of 60 to 90 ° C. because the cleaning mode is performed to remove the paraffin wax fixed to the induction heating unit by energizing and heating the induction heating unit except when the fixing step is performed. Provided are an electromagnetic induction heating type fixing device and an image forming apparatus in which a “wax-adhered image” does not occur on a recording medium to be printed even when a toner containing paraffin wax is used. be able to.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
The first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is the main body of a tandem type color copier as an image forming apparatus, 2 is a writing unit that emits laser light based on input image information, 4 is a document reading unit that reads image information of a document D, and 7 is A paper supply unit for storing a recording medium P such as transfer paper, 11Y, 11M, 11C, and 11BK are photosensitive drums on which toner images of respective colors (yellow, magenta, cyan, and black) are formed, and 12 is a photosensitive drum. 11Y, 11M, 11C, and 11BK are charged. 13 is a developing unit that develops an electrostatic latent image formed on each photoconductor drum 11Y, 11M, 11C, and 11BK, and 15 is each photoconductor drum 11Y. A cleaning unit that collects untransferred toner on 11M, 11C, and 11BK is shown.
Reference numeral 16 denotes an intermediate transfer belt cleaning unit that cleans the intermediate transfer belt 17, 17 an intermediate transfer belt on which toner images of a plurality of colors are transferred, and 18 a color image formed on the intermediate transfer belt 17 as a recording medium. A secondary transfer roller 19 for transferring the toner image onto P is an electromagnetic induction heating type fixing device for fixing a toner image (unfixed image) on the recording medium P.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, image information of the document D placed on the contact glass 5 is optically read by the document reading unit 4. Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.
Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light (exposure light) based on the image information of each color toward the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK are rotated clockwise in FIG. First, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are uniformly charged at a portion facing the charging unit 12 (this is a charging process). Thus, a charged potential is formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. Thereafter, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of the respective laser beams.
In the writing unit 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam passes through a separate optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  Laser light corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 11Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotational axis direction (main scanning direction) of the photosensitive drum 11Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y after being charged by the charging unit 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated to the surface of the second photosensitive drum 11M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11C from the left side of the paper, and an electrostatic latent image of the cyan component is formed. The black component laser beam is applied to the surface of the fourth photosensitive drum 11BK from the left side of the paper, and an electrostatic latent image of the black component is formed.

Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing unit 13, respectively. Then, the respective color toners are supplied from the developing units 13 onto the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (development process). .)
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK after the development process reach the facing portions of the intermediate transfer belt 17, respectively. Here, a transfer bias roller (not shown) is installed at each facing portion so as to abut on the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photoconductive drums 11Y, 11M, 11C, and 11BK are sequentially transferred to the intermediate transfer belt 17 at the position of the transfer bias roller (primary transfer process). .)

Then, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK after the primary transfer process reach positions facing the cleaning unit 15, respectively. Then, the untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is collected by the cleaning unit 15 (this is a cleaning process).
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK pass through a neutralization unit (not shown), and a series of image forming processes on the photoconductive drums 11Y, 11M, 11C, and 11BK is completed.

Thereafter, the intermediate transfer belt 17 on which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 18. At this position, the secondary transfer backup roller sandwiches the intermediate transfer belt 17 between the secondary transfer roller 18 and forms a secondary transfer nip. The four-color toner images formed on the intermediate transfer belt 17 are transferred onto the recording medium P conveyed to the position of the secondary transfer nip (secondary transfer process). At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 17.
Thereafter, the intermediate transfer belt 17 reaches the position of the intermediate transfer cleaning unit 16. At this position, the untransferred toner on the intermediate transfer belt 17 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 17 is completed.

Here, the recording medium P transported to the position of the secondary transfer nip passes through a transport path K1 in which a paper feed roller 8, a registration roller, and the like are installed from a paper feed unit 7 disposed below the apparatus main body 1. It was transported via.
Specifically, a plurality of recording media P are stored in the paper supply unit 7 in a stacked manner. When the paper feed roller 8 is rotationally driven counterclockwise in FIG. 1, the uppermost recording medium P is fed toward the transport path K1.

  The recording medium P transported to the transport path K1 temporarily stops at the position of the roller nip of the registration roller (not shown) that has stopped rotating. Then, the registration roller is driven to rotate in synchronization with the color image on the intermediate transfer belt 17, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 19. At this position, the color image transferred to the surface is fixed on the recording medium P by heat and pressure generated by the fixing roller and the pressure roller.
The recording medium P after the fixing process is discharged as an output image by the paper discharge roller 9 to the outside of the apparatus main body 1 (moving in the direction indicated by the broken line arrow), and a series of image forming processes is completed.

Next, the configuration and operation of the fixing device 19 installed in the image forming apparatus main body 1 will be described in detail.
As shown in FIG. 2, the fixing device 19 includes an induction heating unit 25 (magnetic flux generating means), a fixing roller 20 as a fixing member facing the induction heating unit 25, and a pressure as a pressure member that presses against the fixing roller 20. The roller 30, the inlet guide plate 41, the spur guide plate 42, the separation guide plate 43, the outlet guide plate 50, the thermistors 61 and 62, etc.

Here, the fixing roller 20 as a fixing member is formed by sequentially laminating a heat insulating elastic layer 22 made of foamed silicone rubber or the like and a sleeve layer 21 on a cored bar 23 made of iron or stainless steel, The outer diameter is about 40 mm.
The sleeve layer 21 of the fixing roller 20 is a multilayer structure in which a base material layer, a first antioxidant layer, a heat generating layer, a second antioxidant layer, an elastic layer, and a release layer are sequentially laminated from the inner peripheral surface side. Specifically, the base material layer is formed of stainless steel having a layer thickness of about 40 μm, and the first antioxidant layer and the second antioxidant layer are formed by strike plating treatment of nickel having a layer thickness of 1 μm or less. The heating layer is made of copper having a layer thickness of about 10 μm, the elastic layer is made of silicone rubber having a layer thickness of about 150 μm, and the release layer has a layer thickness of about 30 μm. It is formed of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer).
In the fixing roller 20 configured as described above, the heat generating layer of the sleeve layer 21 is electromagnetically heated by the magnetic flux generated from the induction heating unit 25. The configuration of the fixing roller 20 is not limited to that of the first embodiment. For example, the sleeve layer 21 can be separated without being bonded to the heat insulating elastic layer 22 (fixing auxiliary roller). However, when the sleeve layer 21 (fixing sleeve) is separated, it is preferable to install a member for preventing the sleeve layer 21 from moving in the width direction (thrust direction) during operation.

Here, a spur guide plate 42 in which a plurality of spurs are juxtaposed in the width direction is installed at a position facing the fixing roller 20 and upstream of the nip portion (upstream in the transport direction). The spur guide plate 42 is disposed at a position facing the fixing surface (the surface on which the image is fixed) of the recording medium P fed into the nip portion, and guides the recording medium P to the nip portion. It is. The spur guide plate 42 is formed in a sawtooth shape so that a spur does not rub even if the spur contacts an unfixed image on the recording medium P.
A separation guide plate 43 is provided at a position facing the fixing roller 20 and facing the fixing surface of the recording medium P sent from the nip (on the downstream side in the conveyance direction of the nip). Has been. The separation guide plate 43 is for preventing a problem that the recording medium P after the fixing process sent out from the nip portion is attracted to and wound around the fixing roller 20. That is, when the recording medium P after the fixing process is attracted to the fixing roller 20, the separation guide plate 43 comes into contact with the leading end of the recording medium P to forcibly separate the recording medium P from the fixing roller 20. .

Further, a thermistor 62 as a contact-type temperature detection sensor that contacts the fixing roller 20 is disposed upstream of the nip (on the upstream side in the conveyance direction of the recording medium P) and close to the nip. It is installed. The thermistor 62 is disposed at the end in the width direction on the drive unit side, and detects the surface temperature of the end in the width direction of the fixing roller 20.
Although not shown, a thermopile (non-contact type temperature detection sensor) is disposed at a position facing the center in the width direction of the fixing roller 20.
Then, the temperature on the fixing roller 20 (fixing temperature) is detected by the thermistor 62 and the thermopile, and the heating amount by the induction heating unit 25 is adjusted based on the detection result by the thermistor 62 and the thermopile. In the first embodiment, the induction heating unit 25 is controlled so that the fixing temperature during the fixing process (when passing paper) is 160 to 165 ° C.

Referring to FIG. 2, a pressure roller 30 as a pressure member is formed on a cylindrical member 32 made of aluminum, copper or the like, an elastic layer 31 made of silicone rubber or the like, a release layer made of PFA or the like (not shown). Is formed). The elastic layer 31 of the pressure roller 30 is formed to have a thickness of 1 to 5 mm. The release layer of the pressure roller 30 is formed so that the layer thickness is 20 to 50 μm. The pressure roller 30 is in pressure contact with the fixing roller 20. Then, the recording medium P is conveyed to a pressure contact portion (a nip portion) between the fixing roller 20 and the pressure roller 30.
In the first embodiment, a heater 33 such as a halogen heater is provided in the pressure roller 30 in order to increase the heating efficiency of the fixing roller 20. By supplying electric power to the heater 33, the pressure roller 30 is heated by the radiant heat of the heater 33, and the surface of the fixing roller 20 is heated via the pressure roller 30.

A thermistor 61 as a contact-type temperature detection sensor that contacts the pressure roller 30 is located upstream of the nip portion (on the upstream side in the conveyance direction of the recording medium P) and close to the nip portion. It is arranged. The thermistor 61 is disposed at the end in the width direction on the drive unit side and detects the surface temperature of the end in the width direction of the pressure roller 30.
Although not shown, a thermopile (non-contact type temperature detection sensor) is disposed at a position facing the central portion in the width direction of the pressure roller 30.
Then, the temperature on the pressure roller 30 is detected by the thermistor 61 or the thermopile, and the heating amount by the heater 33 is adjusted based on the detection result by the thermistor 61 or the thermopile.

Here, at a position facing the pressure roller 30 and a position facing the non-fixing surface of the recording medium P fed into the nip portion (on the upstream side of the nip portion), the inlet guide plate 41. Is installed. The inlet guide plate 41 guides the recording medium P fed into the nip portion to the nip portion.
Further, an exit guide plate 50 is installed at a position facing the pressure roller 30 and facing the non-fixing surface of the recording medium P sent from the nip portion (on the downstream side of the nip portion). Has been. The exit guide plate 50 is for guiding the recording medium P after the fixing process sent from the nip portion toward the conveyance path after the fixing process.
With reference to FIG. 3, a grip portion 70 is installed on the outlet guide plate 50. Then, when a jam of the recording medium P occurs at the position of the fixing device 19 (such as a phenomenon in which the recording medium P being transported is jammed), an operator such as a user or a serviceman (the main part of the fixing device 19 ( 3) is taken out from the apparatus main body 1, the gripping portion 70 is gripped, and the outlet guide plate 50 is rotated around the rotation shaft portion 50a (rotation in the direction of the arrow in FIG. 2). Thus, the jammed paper is pulled out from the nip portion with the nip portion exposed. FIG. 4 is a perspective view showing the induction heating unit 25 in a state in which the main part (shown in FIG. 3) of the fixing device 19 is separated.

The induction heating unit 25 includes a coil unit 26 (excitation coil), a core unit 27 (excitation coil core), a coil guide 28, and the like. The coil portion 26 is wound in the width direction (in the direction perpendicular to the paper surface of FIG. 2) by winding a litz wire bundled with thin wires on a coil guide 28 disposed so as to cover a part of the outer peripheral surface of the fixing roller 20. It is extended.
The coil guide 28 is made of a resin material having high heat resistance such as PET (polyethylene terephthalate) containing about 45% of a glass material, and holds the coil portion 26 on the side facing the fixing roller 20. In the first embodiment, the gap between the facing surface 28a of the coil guide 28 (induction heating unit 25) and the outer peripheral surface of the fixing roller 20 is set to 2 ± 0.1 mm.
The core portion 27 is made of a ferromagnetic material such as ferrite (having a relative magnetic permeability of about 2500), and is used to form an efficient magnetic flux toward the heat generating layer of the fixing roller 20, and includes an arch core and a center core. It is composed of a side core and the like.
Referring to FIG. 4, induction heating unit 25 is configured to be separable from the main part of fixing device 19. The main part (the unit shown in FIG. 3) of the fixing device 19 is separated from the induction heating unit 25 shown in FIG. 4 and taken out from the image forming apparatus main body 1 with the door 100 opened. (This is a movement in the right direction in FIG. 1).

The fixing device 19 configured as described above operates in the following manner during a normal fixing process (when paper is passed).
The fixing roller 20 is driven to rotate counterclockwise in FIG. 2 by a drive motor (not shown), and the pressure roller 30 is rotated clockwise accordingly. The sleeve layer 21 (heat generation layer) of the fixing roller 20 is heated by the magnetic flux generated from the induction heating unit 25 at a position facing the induction heating unit 25.

  More specifically, a high frequency alternating current of 10 kHz to 1 MHz (preferably, 20 kHz to 800 kHz) is supplied to the coil unit 26 from a power source unit (not shown) whose frequency is variable in the oscillation circuit, thereby the coil unit. The magnetic field lines are alternately switched in both directions from 26 toward the sleeve layer 21 of the fixing roller 20. By forming an alternating magnetic field in this manner, an eddy current is generated in the heat generating layer of the sleeve layer 21, and the heat generating layer generates Joule heat due to its electric resistance and is induction-heated. Thus, the sleeve layer 21 (fixing roller 20) is heated by induction heating of its own heat generation layer.

Thereafter, the surface of the fixing roller 20 heated by the induction heating unit 25 reaches a contact portion (nip portion) with the pressure roller 30. Then, the toner image T (toner) on the conveyed recording medium P is heated and melted.
Specifically, the recording medium P carrying the toner image T through the image formation process described above is guided between the entrance guide plate 41 (or the spur guide plate 42) and between the fixing roller 20 and the pressure roller 30 ( (It is a nip portion)) (the movement in the transport direction of the arrow Y1). The toner image T is fixed on the recording medium P by the heat received from the fixing roller 20 and the pressure received from the pressure roller 30, and the recording medium P is sent out between the fixing roller 20 and the pressure roller 30 ( This is the movement in the transport direction of the arrow Y2.)
The surface of the fixing roller 20 that has passed through the nip portion then reaches the position facing the induction heating unit 25 again.
Such a series of operations is continuously repeated to complete the fixing step in the image forming process.

Hereinafter, the toner used in the image forming apparatus according to the first embodiment will be described in detail.
In the first exemplary embodiment, the toner T contains paraffin wax having a melting point in the range of 60 to 90 ° C. Specifically, the toner T has base particles containing a paraffin wax having a melting point of 60 ° C. or higher and 90 ° C. or lower and a binder resin, and the base particles are absorbed by the paraffin wax having an endothermic peak in DSC measurement. The heat amount is 3.5 J / g or more and 5.5 J / g or less, and the average circularity is 0.950 or more and 0.980 or less. In this way, the toner T contains paraffin wax having a melting point in the range of 60 to 90 ° C., thereby improving the low-temperature fixability and fixing roller 20 or pressure roller 30 without applying oil to fixing roller 20. The separation property (release property) of the recording medium P can be improved. In particular, as compared with the case where the toner contains other wax (for example, carnauba wax, rice wax, polyethylene wax, polyolefin wax, etc.), the separability (release property) of the recording medium P with respect to the fixing roller 20 and the like. ) Can be increased. In the first embodiment, the melting point of the paraffin wax contained in the toner T is set to 67 ° C.

Hereinafter, the toner T will be described in more detail.
(Particle size distribution)
In order to reproduce minute dots of 600 dpi or more, the toner preferably has a weight average particle diameter (D4) of 3 to 8 μm. The ratio (D4 / Dn) of the weight average particle diameter (D4) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.30. The closer the (D4 / Dn) is to 1.00, the sharper the particle size distribution. For the same reason, it is preferable that 1 to 10% by number of particles of 2 μm or less. Such a toner having a small particle size and a narrow particle size distribution makes the toner charge amount distribution uniform and can provide a high-quality image with little background fogging. In addition, the electrostatic transfer system has a high development efficiency. can do. On the other hand, the problem when reducing the toner particle size is that the non-electrostatic adhesion to the carrier is larger than that of the larger particle size, so it stays on the carrier surface for a long time and is easily subjected to agitation stress and adheres to the carrier surface. It causes the charging ability of the carrier to decrease. In order to prevent such a problem, the number of particles having a size of 2 μm or less is preferably 1 to 10% by number.

Here, the particle size distribution of the toner particles is measured by the Coulter counter method. Examples of the measuring device by the Coulter counter method include Coulter counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.
First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2-20 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. Volume distribution and number distribution are calculated. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter of the toner can be obtained.
As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

(FPIA, average circularity, aspect ratio)
For measurement of ultra-fine toner having an aspect ratio, average circularity of 2 μm or less, measurement is performed using a flow type particle image analyzer (FPIA-3000; manufactured by Sysmex Corporation), and analysis is performed using analysis software attached to the same machine. It was. Specifically, 0.1 to 0.5 ml of 10 wt% surfactant (alkylbenzene sulfonate Neogen SC-A; Daiichi Kogyo Seiyaku) is added to a glass 100 ml beaker, and each toner 0.1 to 0 is added. 0.5 g was added and stirred with a microspatel, and then 80 ml of ion-exchanged water was added. The obtained dispersion was subjected to a dispersion treatment for 3 minutes with an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). Using the FPIA-3000, the dispersion was measured for toner shape and distribution until a density of 5000 to 15000 / μl was obtained. In this measurement method, it is important that the concentration of the dispersion liquid is 5000 to 15000 / μl from the viewpoint of measurement reproducibility of the average circularity. In order to obtain the dispersion concentration, it is necessary to change the conditions of the dispersion, that is, the amount of surfactant to be added and the amount of toner. The amount of the surfactant varies depending on the hydrophobicity of the toner as in the measurement of the toner particle diameter described above, and if it is added in a large amount, noise due to bubbles is generated. If the amount is too small, the toner cannot be sufficiently wetted and dispersion is not achieved. It will be enough. Further, the toner addition amount differs from the particle size, and it is necessary to decrease the small particle size and increase the large particle size. When the toner particle size is 3 to 7 μm, the toner amount is 0.1 to 0. By adding 0.5 g, the dispersion concentration can be adjusted to 5000 to 15000 / μl.
As analysis conditions, an aspect ratio and an average circularity obtained by analyzing the measurement target particle size limit of 2 to 200 μm and the amount of super fine toner of 2 μm or less were obtained. The average circularity and aspect ratio are defined as follows.
Average circularity = (salt circumference equal to particle area) / (particle circumference)
Aspect ratio = (Maximum vertical length) / (Maximum length)
The average circularity is a shape factor that mainly expresses the degree of unevenness of particles, whereas the aspect ratio is a shape factor that mainly expresses the acicularity of particles.

The relationship between the toner shape and the cleaning property (which is the cleaning property in the cleaning unit 15) was evaluated, and it was found that the shape (particularly the aspect ratio) has a close correlation with the cleaning characteristics. In the toner having a small aspect ratio, the interaction force between the toner particles under the compacting condition is large, and the transfer residual toner on the photosensitive drum is damped by the blade in the process of damping (cleaning) the toner with a cleaning blade or the like. The toner tends to aggregate and form a toner layer. Accordingly, the transfer residual toner is blocked not only by the blade but also by the toner layer blocked by the blade, and the amount of toner passing through the cleaning blade is reduced, so that a good cleaning property can be obtained.
When the toner has an aspect ratio of greater than 0.90, the cleaning property is deteriorated. On the other hand, when the aspect ratio is less than 0.80, a trouble caused by low fluidity in a process other than cleaning, specifically, in a pipe Problems such as toner clogging become significant. For this reason, the aspect ratio has an optimum range, and its value is 0.80 to 0.90.

As a problem that has not been found so far, in the process of charging and developing the toner, it has been found that the following tendencies (1) to (4) exist between the shape of the toner and the charging characteristics.
(1) The closer the toner shape is to a sphere, the more likely the toner and the carrier are in point contact, or the toner contacts while rotating on the carrier, so that the toner easily rolls on the surface of the carrier, paraffin wax, low molecular weight A toner component such as a resin component is easily fixed on the carrier. As a result, the charging ability of the carrier is easily lowered. This corresponds to a small contact area between the toner and the carrier (two-component development method) and a small contact area between the toner and the developing sleeve (one-component development method).
(2) On the other hand, when the surface shape of the toner is rough and there are many irregularities, the toner and the carrier are in surface contact, so that the toner is difficult to roll on the surface of the carrier, but the contact area between the toner and the carrier is large, and the paraffin wax In addition, toner components such as low molecular weight resin components are easily fixed on the carrier. As a result, the charging ability of the carrier is easily lowered. This corresponds to a large contact area between the toner and the carrier (two-component development method) and a large contact area between the toner and the developing sleeve (one-component development method).
(3) When the toner and the carrier are stirred for a long time, the influence of the shape appears more strongly than the unevenness. In other words, when the toner and the carrier are stirred in the developing machine for a long time in durability evaluation under actual use conditions, the unevenness on the toner is scraped or deformed, so that the unevenness does not remain. The effect of 1) appears.
(4) For this reason, it is preferable to look at the toner shape related to the chargeability of the toner, especially the decrease in the charging ability of the carrier due to long-term agitation. The lower the aspect ratio, the more difficult it is to roll on the carrier. The higher the value, the closer to the spherical shape, so it is easier to roll on the carrier. Therefore, it is preferable that the aspect ratio of the range in which the toner component is not fixed on the carrier while maintaining a proper contact between the toner and the carrier is in the range of 0.80 to 0.90.

  From the above points, the toner aspect ratio has an optimum range, and its value is 0.80 to 0.90. However, when looking at transfer performance as a new issue, the greater the torque evaluated by this torque evaluation method, the more likely the worm-eating phenomenon occurs during transfer, so the surface properties of the photosensitive drum and intermediate transfer belt, specifically It is necessary to optimize the surface friction coefficient, and it has been found that good results can be obtained in any of the cleanability, developability, and transferability that are trade-offs.

(SF-1, SF-2)
It is preferable that the shape factor SF-1 of the toner is in the range of 130 to 160, and the shape factor SF-2 is in the range of 110 to 140.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) .. Formula (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) .. Formula (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.) and introducing it into an image analyzer (LUSEX3: manufactured by Nireco). 100 pieces were analyzed and calculated.
When a toner having D / S of 15 to 40% and (L / M)> 2 is expressed by SF-1 and SF-2, SF-1 is in the range of 130 to 160, and the shape factor SF-2 is 110 to 110. It is in the range of 140.

(Toner density)
In a full-color image forming apparatus, the toner concentration in the developer is often used in a toner concentration range of 3 to 12 wt%. The image density is controlled in consideration of the particle size of the toner and the carrier in the developer, that is, the surface area, and the occupied area of the toner to be tightened to the carrier surface area is controlled to be 100% or less. This is a measure for maintaining contact and preventing insufficient charging of the toner due to poor contact between the toner and the carrier. Here, in the developer having a high toner concentration, there is a problem that a low melting point wax, a resin or the like in the toner is fixed on the carrier surface and the charging ability of the carrier is lowered.

(Endothermic peak endotherm derived from release agent by DSC)
The glass transition point (Tg) of the toner is usually 40 to 70 ° C., preferably 40 to 60 ° C. If it is less than 40 ° C., the heat resistance of the toner deteriorates, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Due to the coexistence of a modified polyester such as a urea-modified polyester resin, the toner of the present invention tends to have good heat-resistant storage stability even when the glass transition point is low, as compared with known polyester-based toners.
Further, in order to obtain hot offset resistance among the fixing performance, it is preferable that the release material is large. On the other hand, since the release agent is easily fixed to the carrier, in order to maintain the charging ability of the developer carrier for a long period of time. Less is preferred. From this point of view, the content of the release agent in the toner is excellent in hot offset resistance in that the endothermic amount of the endothermic peak derived from the release agent in DSC is in the range of 3.5 to 5.5 J / g. This is desirable in terms of maintaining the charging ability of the carrier. In the first embodiment, as described above, paraffin wax having a melting point in the range of 60 to 90 ° C. is used as the release agent to be contained in the toner T.

Using Shimadzu TA-60WS and DSC-60 as measuring devices, the measurement was performed under the following measurement conditions.
・ Measurement conditions Sample container: Aluminum sample pan (with lid)
Sample amount: 5mg
Reference: Aluminum sample pan (alumina 10mg)
Atmosphere: Nitrogen (flow rate 50 ml / min)
Temperature conditions Starting temperature: 20 ° C
Temperature increase rate: 10 ° C / min
End temperature: 150 ° C
Holding time: None Temperature drop: 10 ° C / min
End temperature: 20 ° C
Holding time: None Temperature increase rate: 10 ° C / min
End temperature: 150 ° C

The measurement results were analyzed using the data analysis software (TA-60, version 1.52) manufactured by Shimadzu Corporation. In the analysis method, the DrDSC curve, which is the DSC differential curve of the second temperature rise, specifies two locations on the low-temperature side and high-temperature side of the endothermic peak corresponding to the endotherm when the release agent melts. The peak endotherm is obtained using the peak analysis function. The endothermic peak corresponding to the endotherm at the time of melting of the release agent is an endothermic peak obtained by performing DSC measurement of the release agent alone by the above procedure.
In addition, the toner Tg is designated with a range of ± 5 ° C. around the point showing the maximum peak on the lowest temperature side of the DrDSC curve, which is the DSC differential curve of the second temperature increase, and is peaked using the peak analysis function of the analysis software. Find the temperature. Next, the maximum endothermic temperature of the DSC curve is determined using the peak analysis function of the analysis software in the range of the peak temperature + 5 ° C. and −5 ° C. in the DSC curve. The temperature shown here corresponds to the Tg of the toner.

Other toner constituent materials will be described.
-Modified polyester-
The toner of the present invention contains a modified polyester (i) as a binder resin. The modified polyester (i) refers to a state in which a bonding group other than an ester bond is present in the polyester resin, or resin components having different configurations are bonded to the polyester resin by a covalent bond, an ionic bond, or the like. Specifically, the polyester terminal is modified by introducing a functional group such as a carboxylic acid group or an isocyanate group that reacts with a hydroxyl group into the polyester terminal and further reacting with an active hydrogen-containing compound.

  Examples of the modified polyester (i) include urea-modified polyester obtained by a reaction between a polyester prepolymer (A) having an isocyanate group and amines (B). As the polyester prepolymer (A) having an isocyanate group, a polyester having a polycondensate of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC) and having an active hydrogen group is further added to a polyvalent isocyanate compound (PIC). And those reacted with. Examples of the active hydrogen group possessed by 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.

The urea-modified polyester is produced as follows.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) include 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, 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 bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. As trihydric or higher polyhydric alcohol (TO), trihydric or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) and a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) 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) And naphthalenedicarboxylic acid). 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 polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  Examples of the polyvalent isocyanate compound (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.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40% by mass, preferably 1 to 30% by mass, more preferably 2 to 20% by mass. %. If it is less than 0.5% by mass, 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 mass, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the polyester 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 urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acids (B5), and (B6) in which the amino group of (B1) to (B5) is blocked.
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.).
Examples of the trivalent or higher polyvalent amine compound (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.
As (B6) which blocked the amino group of (B1) to (B5), ketimine compounds obtained from the amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.) of (B1) to (B5), And oxazolidine compounds.
Among these amines (B), preferred are (B1) and a mixture of (B1) and a small amount of (B2).
The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.
The urea-modified polyester may contain a urethane bond together with 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.

The modified polyester (i) is produced by a one-shot method or a prepolymer method. The weight average molecular weight of the modified polyester (i) is usually 10,000 or more, preferably 20,000 to 10,000,000, more preferably 30,000 to 1,000,000. The peak molecular weight at this time is preferably 1000 to 10000. When the molecular weight is less than 1000, the elongation reaction hardly occurs, the elasticity of the toner is small, and as a result, the resistance to hot offset deteriorates. On the other hand, when it exceeds 10,000, the problem in production becomes high in the deterioration of fixability, particle formation and pulverization. The number average molecular weight of the modified polyester (i) is not particularly limited when the unmodified polyester (ii) described later is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. (I) When used alone, the number average molecular weight is usually 20000 or less, preferably 1000 to 10000, and more preferably 2000 to 8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color device are deteriorated.
In the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B) to obtain the modified polyester (i), a reaction terminator is used as necessary to adjust the molecular weight of the resulting urea-modified polyester. be able to. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those blocked (ketimine compounds).

-Unmodified polyester-
Not only the modified polyester (i) can be used alone, but also this (i), unmodified polyester (ii) can be contained as a binder resin component. By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color device are improved, which is preferable to single use. Examples of (ii) include polycondensates of polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) similar to the polyester component of (i) above, and preferred ones are also the same as (i). . (Ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, and may be modified with a urethane bond, for example. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Accordingly, the polyester component (i) and (ii) preferably have similar compositions. When (ii) is contained, the weight ratio of (i) and (ii) 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. If the weight ratio of (i) 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 peak molecular weight of (ii) is usually 1000 to 10,000, preferably 2000 to 8000, and more preferably 2000 to 5000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (ii) is preferably 1 to 5, more preferably 2 to 4. Since a high acid value wax is used as the wax, the low acid value binder leads to electrification and high volume resistance, so that it is easy to match the toner used for the two-component developer.

  The glass transition point (Tg) of the binder resin is usually 35 to 70 ° C., preferably 40 to 65 ° C., more preferably 40 to 60 ° C. when toner particles containing other toner materials are used. If it is less than 35 ° C., the heat resistant storage stability of the toner is deteriorated, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the toner of the present invention tends to have good heat storage stability even when the glass transition point is low, as compared with known polyester-based toners. Show.

-Colorant-
As the colorant, known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, Yellow lead, Titanium yellow, Polyazo yellow, Oil yellow, Hansa yellow (GR, A, RN, R), Pigment yellow L, Benzidine yellow (G, GR), Permanent yellow (NCG), Vulcan fast yellow (5G, R) ), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Se Red, parachlor ortho nitroa Lynn Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Po Azo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Anine green, anthraquinone green, titanium oxide, zinc white, lithopone and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by mass, preferably 3 to 10% by mass with respect to the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

  The masterbatch can be obtained by mixing and kneading a masterbatch resin and a colorant under high shear. In this case, an organic solvent can be used in order to enhance the interaction between the colorant and the resin. In addition, a so-called flushing method, which is a wet cake of a colorant, is a method of mixing and kneading an aqueous paste containing water of a colorant together with a resin and an organic solvent, transferring the colorant to the resin side, and removing moisture and organic solvent components. Since it can be used as it is, it does not need to be dried and is preferably used. For mixing and kneading, a high shear dispersion device such as a three-roll mill is preferably used.

-Charge control agent-
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salt or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSYVP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (manufactured by Nippon Carlit) ), Copper phthalocyanine, perylene, quinacridone, azo face And other polymeric compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of the charge control agent used is determined based on the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. However, it is preferably used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, the range of 0.2-5 mass parts is good. When the amount exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

―Inorganic filler―
As the inorganic filler for controlling the toner shape, montmorillonite or an organic modified product thereof (Clayton APA) is used. The function of the inorganic filler is to form irregularities on the toner surface, and the mechanism is as follows.
In a toner manufacturing method in which a toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles, the inorganic filler in the toner material liquid moves to the interface between the organic solvent and the aqueous solvent during emulsification, and the emulsion dispersion Collect on the surface shape of the (reactant). Next, in the step of removing the organic solvent from the emulsified dispersion (reactant), washing and drying, the inorganic filler present on the surface forms irregularities on the surface of the reaction product. Therefore, in obtaining the shape of the present invention, the amount of the inorganic filler can be controlled within the range of 0.1 to 10 parts by weight to change the shape, and the larger the amount of the inorganic filler, the more SF-1 and SF-2. The value of becomes larger and deforms.

-External additive-
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 −3 to 0.3 μm. Moreover, it is preferable that the specific surface area by BET method is 100-500 m <2> / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5% by mass of the toner, and particularly preferably 0.01 to 2.0% by mass.
Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
In addition, polymer fine particles, such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, methacrylic acid ester, acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine, nylon, thermosetting Examples thereof include polymer particles made of a resin.

Such external additives can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .
In particular, it is preferable to use hydrophobic silica and hydrophobic titanium oxide obtained by subjecting silica and titanium oxide to the above surface treatment.

Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.
(Production method of toner binder)
The toner binder can be manufactured by the following method. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with a polyvalent isocyanate compound (PIC), and the prepolymer (A) which has an isocyanate group is obtained. Further, (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a polyester modified with a urea bond.
When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers Inactive to polyvalent isocyanate compounds (PIC) such as benzene (such as tetrahydrofuran).
When the unmodified polyester (ii) is used in combination, (ii) is produced by the same method as that for the polyester having a hydroxyl group, and this is dissolved and mixed in the solution after completion of the reaction (i).

(Toner production method)
1) A toner material liquid is prepared by dispersing a colorant, unmodified polyester (i), a polyester prepolymer (A) having an isocyanate group, and a release agent in an organic solvent. The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. The usage-amount of an organic solvent is 0-300 mass parts normally with respect to 100 mass parts of polyester prepolymers, Preferably it is 0-100 mass parts, More preferably, it is 25-70 mass parts.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by mass of the toner material liquid is usually 50 to 2000 parts by mass, preferably 100 to 1000 parts by mass. If the amount is less than 50 parts by mass, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 2000 parts by mass, it is not economical.

The glass transition point (Tg) of the resin fine particles dispersed in the aqueous medium is preferably 50 to 110 ° C., more preferably 50 to 90 ° C. When the glass transition point (Tg) is less than 50 ° C., toner storage stability is obtained. Or the probability of fixing and aggregation in the toner recovery path during recycling increases. When the glass transition point (Tg) is higher than 110 ° C., the resin fine particles hinder the adhesion to the fixing paper, and the fixing minimum temperature is increased. A more preferred range is a range of 50 to 70 ° C.
The weight average molecular weight is desirably 100,000 or less. Preferably it is 50,000 or less. The lower limit is usually 4000. When the weight average molecular weight exceeds 100,000, the resin fine particles inhibit the adhesiveness with the fixing paper, and the minimum fixing temperature increases.

  As the resin fine particles, known resins can be used as long as they can form an aqueous dispersion, and thermoplastic resins or thermosetting resins may be used. Examples thereof include vinyl resins, polyurethane resins, epoxy resins, and polyester resins. It is done. As the resin fine particles, two or more of the above resins may be used in combination. Among these, those made of a vinyl resin, a polyurethane resin, an epoxy resin, a polyester resin, or a combination resin thereof are preferable because an aqueous dispersion of fine spherical resin particles is easily obtained.

Vinyl resins are polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene-acrylic acid ester resins, styrene-methacrylic acid ester resins, styrene-butadiene copolymers, acrylic acid-acrylic acid ester polymers. Methacrylic acid-acrylic acid ester polymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and the like.
In the resin fine particles, the volume average particle diameter is a value measured with a light scattering photometer (manufactured by Otsuka Electronics), and is 10 to 200 nm, preferably 20 to 80 nm.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.
Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  In addition, examples of the cationic surfactant include aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. Benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent F-300 (Neos), and the like.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium or to prevent the wax from being exposed to the outermost surface of the toner. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%.
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxypropyl , 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole , Nitrogen-containing compounds such as ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, polyoxypro Len, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene Polyoxyethylenes such as nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

3) At the same time as the preparation of the emulsion, the amines (B) are added to react with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent-based toner base particles can be produced by removing the solvent. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.
The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

Hereinafter, the control of the fixing device 19 that is characteristic in the first embodiment will be described in detail with reference to FIGS.
Referring to FIG. 5, in the first embodiment, the induction heating unit 25 is energized / heated except when the fixing step is performed (when the recording medium P is passed through the nip portion). Then, a cleaning mode for removing the paraffin wax adhering to the induction heating unit 25 is performed for a predetermined time.

  In the cleaning mode, when a toner containing paraffin wax having a low melting point (in the range of 60 to 90 ° C.) is used, the paraffin wax volatilizes at the position of the nip portion or the surface of the fixing roller 20 to volatilize. This is performed in order to suppress the problem that the paraffin wax adhered and adheres to the facing surface 28a of the induction heating unit 25 (coil guide 28) facing the fixing roller 20. That is, paraffin wax adheres and accumulates on the opposing surface 28a of the induction heating unit 25 (coil guide 28) (adhering to a position surrounded by a broken line in FIGS. 2 and 4), and the accumulated paraffin is accumulated. When the height of the wax exceeds a minute gap (about 2 mm) between the fixing roller 20 and the facing surface 28a, a part of the paraffin wax fixed to the induction heating unit 25 adheres to the fixing roller 20. . Then, the paraffin wax adhering to the fixing roller 20 adheres onto the recording medium P at the position of the nip portion during the fixing process, and a “wax adhesion image” is output. In contrast, in the first embodiment, since the cleaning mode is performed at regular intervals to heat the induction heating unit 25 (coil guide 28), the opposing surface 28a of the induction heating unit 25 is paraffinized. Even if the wax is fixed, the paraffin wax is liquefied by heating, and the paraffin wax flows in the direction of gravity along the opposing surface 28a without accumulating the paraffin wax at that position.

In FIG. 5, the cleaning mode is executed after the fixing process is completed. Here, in the cleaning mode, the induction heating unit 25 is energized and heated so that the heating temperature between the opposed surface 28a of the induction heating unit 25 and the vicinity thereof is equal to or higher than the melting point of the paraffin wax. Specifically, in the first embodiment, referring to FIG. 5, heating by induction heating unit 25 is performed based on the detection result by thermistor 62 or thermopile so that the fixing temperature in the cleaning mode is about 185 ° C. The amount is adjusted. In the first embodiment, the induction heating unit 25 is controlled so that the fixing temperature during the fixing process (when passing paper) is 160 to 165 ° C. That is, in the cleaning mode, the heating amount of the induction heating unit 25 is adjusted so that the surface temperature of the fixing roller 20 is higher than that in the fixing process.
Here, the first embodiment is configured such that the heating temperature in the cleaning mode can be varied. Specifically, it is configured such that the control value (target value) of the fixing temperature in the cleaning mode can be varied by operating the operation unit (not shown) of the apparatus main body 1 by the service person. . As a result, an optimum cleaning mode can be set according to the use conditions of the user. For example, as the fixing temperature in the cleaning mode is set higher, there is an advantage that the cleaning time can be shortened because the temperature rise of the facing surface 28a is accelerated.

In addition, the energization time of the induction heating unit 25 in the cleaning mode is preferably set to 20 seconds or more. In the first embodiment, the energization time of the induction heating unit 25 in the cleaning mode is set to 160 seconds. Thereby, since heat is sufficiently applied to the paraffin wax fixed to the induction heating unit 25, the fixed paraffin wax can be reliably liquefied and removed.
Here, the first embodiment is configured such that the energization time (heating time) to the induction heating unit 25 in the cleaning mode can be changed without changing the fixing temperature in the cleaning mode. Specifically, it is configured such that the operating time of the cleaning mode can be varied by operating a service man (not shown) of the apparatus main body 1 by a service person. As a result, an optimum cleaning mode can be set according to the use conditions of the user. For example, the setting value (default value) of the fixing temperature in the cleaning mode is not changed, and only the energization time is controlled while maintaining the setting value, thereby suppressing deterioration of the fixing roller 20 due to heat. be able to. In addition, when there is a print request immediately after the cleaning mode, there is a possibility of causing hot offset or winding jam depending on the fixing temperature in the cleaning mode. Therefore, it is desirable that the energization time can be varied separately from the fixing temperature in the cleaning mode.

Here, in the first embodiment, in the cleaning mode, the induction heating unit 25 is energized and heated, and the fixing roller 20 runs (rotates). Specifically, when the cleaning mode is executed, the induction heating unit 25 is energized and the drive unit is operated to rotate the fixing roller 20 and the pressure roller 30. That is, in the cleaning mode, the fixing device 20 is driven idle (driven without paper passing). As a result, when the induction heating unit 25 is energized, a part of the outer peripheral surface of the fixing roller 20 is locally electromagnetically induction heated, thereby preventing a problem in which thermal damage occurs at that position. .
It is desirable in terms of noise suppression that the traveling speed of the fixing roller 20 in the cleaning mode (the linear speed on the outer peripheral surface) be as low as possible. Specifically, the noise can be suppressed by setting the traveling speed of the fixing roller 20 in the cleaning mode to the lowest linear speed of the fixing device 19 (about 50 mm / second in the first embodiment). it can.
In the first embodiment, the fixing roller 20 and the pressure roller 30 are rotationally driven to perform the cleaning mode. However, the fixing roller 20 and the pressure roller 30 are not rotated but only energized (heated). It is also possible to execute the cleaning mode. Furthermore, if the cleaning mode is executed by setting the fixing roller 20 and the pressure roller 30 to the depressurized state or the non-contact state, the heat of the fixing roller 20 is not easily taken away by the pressure roller 30, and wasteful power consumption is achieved. It can suppress, and the malfunction which both rollers 20 and 30 deteriorate with pressure can be reduced.

FIG. 6 is a flowchart showing control of the fixing device related to the cleaning mode.
As shown in FIG. 6, first, when a printing operation (image forming process) is started in the image forming apparatus (step S1), the number counter is updated in accordance with the number of printed sheets (output number) during the job. (Step S2). Specifically, an exit sensor (not shown) disposed at the position of the paper discharge roller 9 of the apparatus main body 1 detects the recording medium P that has been printed and discharged to the outside of the apparatus. A signal is transmitted to the control unit, and the value of the number counter stored in the memory is updated.
When the printing operation is completed (step S3), it is determined whether or not the number counter has reached a predetermined value A (in the first embodiment, 5000 is set) (step S4). As a result, when it is determined that the number counter has not reached the predetermined value A, it is determined that the paraffin wax is not fixed to the induction heating unit 25, and this flow is finished (step S10).

On the other hand, when it is determined in step S4 that the number counter has reached the predetermined value A, the cleaning mode is executed on the assumption that the paraffin wax is fixed to the induction heating unit 25. (Step S5). Specifically, the induction heating unit 25 is energized and the fixing device 19 is idly driven.
Then, while the cleaning mode is being executed, it is determined whether or not there is a print request (a command for performing a print sent to the control unit by a user operation on the operation unit) (step S6). As a result, if it is determined that there is no print request, a request for further energy saving mode (when there is no print request for a predetermined time, etc., the control unit is used to shift the control temperature of the fixing temperature lower). It is determined whether there is a command that is automatically sent (step S7). As a result, when it is determined that there is no request for the energy saving mode, the cleaning mode is terminated after the cleaning mode is executed for a predetermined time (step S9). In the first embodiment, the cleaning mode execution time is set to 160 seconds.
Thereafter, the number counter stored in the memory is reset (step S9), preparation for execution of the next cleaning mode is performed, and this flow is finished (step S10).

Here, in the first embodiment, when there is a print request (a request for performing printing with a fixing process) when the cleaning mode is being performed, the cleaning mode is interrupted and a print request is made. Is controlled to be executed preferentially. Specifically, when the cleaning mode is interrupted, control is performed so that the cleaning mode is newly performed for a predetermined time (160 seconds) after execution of the print request is completed.
Specifically, if it is determined in step S6 in FIG. 6 that there is a print request while the cleaning mode is being executed, the cleaning mode is temporarily interrupted (step S11). Then, the printing operation is started based on the print request received in step S6 (step S12). When printing is completed (step S13), the flow after step S5 is repeated. That is, the cleaning mode is executed from the beginning. Thus, by giving priority to the user's print request over the cleaning mode, the waiting time in the cleaning mode can be eliminated for the user who performs printing.

In the first embodiment, when there is a request for performing the energy saving mode when the cleaning mode is performed, the cleaning mode is preferentially executed, and the number of sheets is counted after the cleaning mode is completed. Is reset to execute the energy saving mode request.
Specifically, if it is determined in step S7 of FIG. 6 that the energy saving mode is requested while the cleaning mode is being executed, the cleaning mode is continued without interruption (step S14). When the cleaning mode for a predetermined time (160 seconds) ends (step S15), the sheet count is reset thereafter (step S16), and the energy saving mode is executed (step S19). Thus, by giving priority to the cleaning mode over the energy saving mode, it is possible to reliably suppress the occurrence of the “wax adhesion image”.

Even when there is a request for the power-off mode (a command for turning off the power of the apparatus main body sent to the control unit by the operation of the user's operation unit, etc.), the same flow as the energy saving mode described above (This is the flow after step S7.) However, when the main switch is turned off and the power is turned off during execution of the cleaning mode (when the main switch is turned off by the user and the power supply is forcibly cut off), the main switch is subsequently turned on. The cleaning mode is executed again after the first printing is completed after being turned on (powered on). This is because the sheet count is reset upon completion of the cleaning mode, and the sheet count is not reset even if the power is forcibly turned off during the cleaning mode.

  In the first embodiment, an exit sensor (not shown) disposed at the position of the paper discharge roller 9 detects the recording medium P discharged outside the apparatus, and based on the detection signal. Updated the value of the number counter. On the other hand, the value of the number counter can be updated based on a print request by the user. However, since the method according to the first embodiment using the exit sensor counts only the recording medium P that is actually discharged out of the fixing device 19, the timing at which the cleaning mode should be executed is determined. Judgment can be made reliably. Therefore, the position where the exit sensor is installed can be the exit position of the fixing device 19 instead of the position of the paper discharge roller 9 of the apparatus main body 1.

  In the first embodiment, the cleaning mode is performed at regular intervals (every 5000 sheets). However, the cleaning mode may be configured to be variable. As a result, an optimum cleaning mode can be set according to the use conditions of the user. Specifically, for users who frequently print photographic images and the like that consume a large amount of toner, for example, by setting the interval for performing the cleaning mode to 4000 sheets, the optimal timing according to the usage conditions of the user can be obtained. It becomes possible to perform the cleaning of the fixed wax.

In the first embodiment, the interval for performing the cleaning mode is determined by the number of sheets of the recording medium P (number counter) conveyed to the nip portion. On the other hand, the interval at which the cleaning mode is performed can be determined by the travel distance or travel time of the fixing roller 20. Specifically, the cleaning mode can be executed each time the rotation time of the drive motor that rotationally drives the fixing roller 20 reaches a predetermined time.
Furthermore, the interval at which the cleaning mode is performed can be determined by the amount of toner consumption. Specifically, the image forming process is performed by obtaining the image ratio of the image formed on the recording medium P from the duty of the writing unit 2 that forms an electrostatic latent image on each of the photosensitive drums 11Y, 11M, 11C, and 11BK. The amount of toner consumed is calculated. Since there is a correlation between the toner consumption and the amount of paraffin wax that volatilizes at the position of the fixing device 19, the “wax adhesion image” is generated by performing the cleaning mode every time the toner consumption reaches a predetermined value. Can be suppressed.

  The cleaning mode is preferably configured to be forcibly executed by a serviceman or user operation. Specifically, the service mode or the user operates the operation unit (not shown) of the apparatus body 1 so that the cleaning mode is forcibly performed even if the timing for performing the cleaning mode has not been reached. It is composed. As a result, even if an unexpected “wax adhesion image” has occurred, the subsequent generation of the “wax adhesion image” can be suppressed.

  As described above, in the first embodiment, in addition to the time when the fixing process is performed, a cleaning mode is performed in which the induction heating unit 25 is energized and heated to remove the paraffin wax fixed to the induction heating unit 25. Therefore, even when the toner T containing paraffin wax having a melting point in the range of 60 to 90 ° C. is used, it is possible to reliably prevent the occurrence of “wax adhesion image” on the recording medium P to be printed out. can do.

Embodiment 2. FIG.
7 and 8, the second embodiment of the present invention will be described in detail.
FIG. 7 is a graph showing a change in the fixing temperature of the fixing device in the second embodiment, and corresponds to FIG. 5 in the first embodiment. FIG. 8 is a flowchart showing control of the fixing device and corresponds to FIG. 6 in the first embodiment. The fixing device according to the second embodiment is different from that according to the first embodiment in the control method after the cleaning mode is interrupted.

In the second embodiment, similarly to the first embodiment, when there is a print request when the cleaning mode is being performed, the cleaning mode is interrupted and the print request is executed with priority. I have control.
However, in the second embodiment, when the cleaning mode is interrupted, after execution of the print request is completed so that the integrated time before and after the cleaning mode is interrupted matches a predetermined time (160 seconds). Control to perform the cleaning mode.

  Specifically, referring to the flowchart of FIG. 8, if it is determined in step S6 that there is a print request while the cleaning mode is being executed, the cleaning mode is temporarily interrupted (step S11). . Then, the printing operation is started based on the print request received in step S6 (step S12). When printing is completed (step S13), the cleaning mode is executed for the remaining time (step S17). For example, if the cleaning mode is executed for 100 seconds before the cleaning mode is interrupted, the cleaning mode is executed for 60 seconds in step S17 (the integration execution time is 160 seconds before and after the cleaning mode is interrupted). Become.). Thus, by giving priority to the user's print request over the cleaning mode, the waiting time due to the cleaning mode can be eliminated. 8 is the same as the control flow of FIG. 6 in the first embodiment except for the control flow after step S17, and the description thereof is omitted.

  As described above, also in the second embodiment, as in the first embodiment, the paraffin wax is fixed to the induction heating unit 25 by energizing and heating the induction heating unit 25 except when the fixing step is performed. Since the cleaning mode for removing the toner is performed, even when the toner T containing paraffin wax having a melting point in the range of 60 to 90 ° C. is used, the “wax adhesion” It is possible to surely prevent the occurrence of “image”.

Embodiment 3 FIG.
A third embodiment of the present invention will be described in detail with reference to FIG.
FIG. 9 is a cross-sectional view illustrating the fixing device according to the third embodiment, and corresponds to FIG. 2 according to the first embodiment. The fixing device in the third embodiment is different from that in the first embodiment in which the fixing roller 65 is used as the fixing member in that the fixing belt 65 is used as the fixing member.

  As shown in FIG. 9, the fixing device 20 according to the third embodiment includes an induction heating unit 25, a fixing belt 65 as a fixing member, a heating roller 66, a fixing auxiliary roller 67, a pressure roller 30 as a pressure member, Etc.

Here, the fixing auxiliary roller 67 is formed by forming an elastic layer such as silicone rubber on the surface of a cored bar made of stainless steel or the like. The elastic layer of the fixing auxiliary roller 67 has a thickness of 1 to 10 mm and an Asker hardness of 30 to 60 degrees.
The heating roller 66 is a cylindrical body formed of stainless steel or the like. The heating roller 66 and the fixing auxiliary roller 67 rotate counterclockwise in FIG.
The fixing belt 65 including the heat generating layer is stretched and supported by a heating roller 66 and a fixing auxiliary roller 67. The fixing belt 65 has a base layer, an elastic layer, a heat generation layer, a silicone rubber layer, and a release layer laminated from the inner peripheral surface side. The heat generating layer of the fixing belt 65 is heated by electromagnetic induction by the magnetic flux generated from the induction heating unit 25.

The fixing device 19 configured in this way operates as follows during the fixing process.
By the rotation driving of the fixing auxiliary roller 67, the fixing belt 65 rotates counterclockwise in FIG. 9, the heating roller 66 also rotates counterclockwise, and the pressure roller 30 also rotates clockwise. The fixing belt 65 is heated at a position facing the induction heating unit 25.
Specifically, by supplying a high-frequency alternating current of 10 kHz to 1 MHz (preferably 20 kHz to 800 kHz) from the power supply unit (not shown) to the coil unit 25, the magnetic field lines are alternately switched in both directions toward the heat generating layer. Formed. By forming the alternating magnetic field in this manner, an eddy current is generated in the heat generating layer of the fixing belt 65, Joule heat is generated by the electric resistance of the heat generating layer, and the heat generating layer is heated. In this way, the fixing belt 65 is heated by the heat generated by its own heat generating layer.

Thereafter, the surface of the fixing belt 65 heated by the induction heating unit 25 reaches a contact portion with the pressure roller 30. Then, the toner image T (toner) on the conveyed recording medium P is heated and melted. The surface of the fixing belt 65 that has passed through the nip portion then reaches the position facing the induction heating unit 25 again. Such a series of operations is continuously repeated to complete the fixing step in the image forming process.
In the third embodiment, the cleaning mode is performed at the optimum timing, except when the fixing process is performed, as in the above embodiments.

  In the third embodiment, the heat generating layer heated by induction by the induction heating unit 25 is provided on the fixing member (fixing belt 65). However, the heat generating layer may be provided on the heating roller 66. In such a case, the heating roller 66 is heated by electromagnetic induction by the induction heating unit 25, and the fixing belt 65 is indirectly heated by the heating roller 66.

  As described above, also in the third embodiment, the paraffin wax that is fixed to the induction heating unit 25 by energizing and heating the induction heating unit 25 except when the fixing process is performed, as in the above embodiments. Since the cleaning mode for removing the toner is performed, even when the toner T containing paraffin wax having a melting point in the range of 60 to 90 ° C. is used, the “wax adhesion” It is possible to surely prevent the occurrence of “image”.

  In each of the above embodiments, the present invention is applied to a fixing device using the fixing roller 20 or the fixing belt 65 as a fixing member and the pressure roller 30 as a pressure member. The present invention can also be applied to an electromagnetic induction heating type fixing device using the above and an electromagnetic induction heating type fixing device using a pressure belt or a pressure pad as a pressure member. In such a case, the same effects as those of the above embodiments can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view illustrating a fixing device. FIG. 3 is a perspective view illustrating a part of the fixing device. It is a perspective view which shows the induction heating part of a fixing device. 5 is a graph showing a change in fixing temperature during a fixing process and a change in fixing temperature during a cleaning mode. 6 is a flowchart illustrating control of the fixing device. It is a graph which shows the change of the fixing temperature of the fixing device in Embodiment 2 of this invention. It is a flowchart which shows control of the fixing device in FIG. It is sectional drawing which shows the fixing device in Embodiment 3 of this invention.

Explanation of symbols

1 image forming apparatus body (apparatus body),
19 fixing device,
20 fixing roller (fixing member),
25 induction heating unit,
28 Coil guide,
28a facing surface,
30 pressure roller (pressure member),
65 fixing belt (fixing member),
66 heating roller,
67 Fixing auxiliary roller.

Claims (20)

A fixing device that performs a fixing process for fixing toner on a recording medium conveyed to a nip portion,
A fixing member that forms the nip portion together with the pressure member and heats and melts the toner while traveling in a predetermined direction;
An induction heating unit facing the outer peripheral surface of the fixing member and heating the fixing member directly or indirectly by electromagnetic induction;
With
The toner contains paraffin wax having a melting point in the range of 60 to 90 ° C.,
In addition to the time when the fixing step is performed, the fixing device is characterized in that a cleaning mode for removing the paraffin wax fixed to the induction heating unit by energizing and heating the induction heating unit is performed for a predetermined time.   The fixing device according to claim 1, wherein in the cleaning mode, the induction heating unit is energized / heated and the fixing member travels.   The fixing device according to claim 1, wherein the cleaning mode is performed at regular intervals.   The fixing device according to claim 3, wherein the interval at which the cleaning mode is performed is variable.   The fixing device according to claim 3, wherein the interval at which the cleaning mode is performed is determined by the number of recording media conveyed to the nip portion.   The fixing device according to claim 3, wherein the interval for performing the cleaning mode is determined by a travel distance or a travel time of the fixing member.   The fixing device according to claim 3, wherein the interval at which the cleaning mode is performed is determined by a consumption amount of the toner.   In the cleaning mode, the induction heating unit is energized and heated so that the heating temperature between the surface facing the induction heating unit facing the fixing member and the vicinity thereof is equal to or higher than the melting point of the paraffin wax. The fixing device according to claim 1.   The fixing device according to claim 8, wherein the heating temperature in the cleaning mode is variable.   The fixing device according to claim 1, wherein the induction heating unit is energized for 20 seconds or longer in the cleaning mode.   The fixing device according to claim 10, wherein the energization time in the cleaning mode is variable.   In the cleaning mode, the induction heating unit is energized / heated and the fixing member travels, and the traveling speed of the fixing member is set to 50 mm / second or more and less than the maximum linear speed of the apparatus. The fixing device according to any one of claims 1 to 11.   The fixing device according to claim 12, wherein a traveling speed of the fixing member in the cleaning mode is variable.   The fixing device according to claim 1, wherein the cleaning mode is forcibly executed by a serviceman or a user operation.   The print mode is preferentially executed by interrupting the cleaning mode when there is a print request for printing with the fixing step when the cleaning mode is being performed. The fixing device according to claim 1.   The fixing device according to claim 15, wherein, when the cleaning mode is interrupted, the cleaning mode is newly performed for the predetermined time after the execution of the print request is completed.   16. When the cleaning mode is interrupted, the cleaning mode is performed after execution of the print request is completed so that an integrated time before and after the cleaning mode is interrupted matches the predetermined time. The fixing device according to 1.   18. The cleaning mode according to claim 1, wherein, when the printing with the fixing step is performed for the same time or more as the predetermined time, the cleaning mode is performed after the printing is completed. Fixing device.   When there is a request for performing an energy saving mode or a power-off mode when the cleaning mode is performed, the cleaning mode is preferentially executed, and the request is executed after the cleaning mode ends. The fixing device according to claim 1, wherein the fixing device is a fixing device.   An image forming apparatus comprising the fixing device according to claim 1.

Images