JP2011059463A - Image forming method, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method in which separability after fixing is improved and by which a high-quality image free from gloss unevenness can be obtained. <P>SOLUTION: The image forming method uses toner including roughness particles (filler) having a volume average particle diameter of 1.0-5.0 μm and a shape change rate of ≤10% at 200°C and 0.03 N/mm<SP>2</SP>, and a fixing device in which a fixing roller 61 has a crown part 61a whose outer peripheral surface is formed in the shape of a crown and an inverted crown part 61b whose outer peripheral surface is formed in the shape of an inverted crown, and a pressure roller 62 has a crown part 62a whose outer peripheral surface is formed in the shape of a crown and an inverted crown part 62b whose outer peripheral surface is formed in the shape of an inverted crown, wherein the fixing roller 61 and the pressure roller 62 are brought into pressure-contact with each other in such a way that the crown part 61a of the fixing roller 61 is made to correspond to the inverted crown part 62b of the pressure roller 62 and the inverted crown part 61b of the fixing roller 61 is made to correspond to the crown part 62a of the pressure roller 62. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming method, a process cartridge, and an image forming apparatus using a specific fixing device and a specific toner, and more specifically, a nip portion formed by a roll pair or a nip portion formed by a roll and a belt. Passing through a recording medium carrying an unfixed toner image, heating and pressurizing to fix the toner image on the recording medium, an image forming method using a specific toner, and a process cartridge used in this image forming method And an image forming apparatus.

  An image forming apparatus employing an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a combination of these machines often uses a fixing device for fixing a toner image transferred onto a recording sheet as a recording medium by heat and pressure. It has been. Examples of the fixing device include a type in which a pressure roller is pressed against a fixing roller having a heating source such as a heater therein, and a type in which an endless pressure belt is pressed against the fixing roller by a pressing member. These fixing devices pass the recording paper on which the toner image is transferred through a fixing nip formed at a pressure contact portion between the fixing roller and the pressure roller or a pressure contact portion between the fixing roller and the pressure belt. The recording paper is heated and pressurized to fix the toner image on the recording paper.

  FIG. 16 is a simplified diagram of a fixing device having the fixing roller 100 and the pressure roller 200. As shown in FIG. 16, the recording paper P onto which the toner image T has been transferred passes through the fixing nip N between the fixing roller 100 and the pressure roller 200, and is then carried out in the direction of the one-dot chain line a. It has become. However, since the heat fixing type fixing device as described above melts the toner T on the recording paper P by heat at the time of fixing, the conveyance direction of the recording paper P is caused by the adhesion of the melted toner T to the fixing roller 100. The direction may be changed from the direction of the alternate long and short dash line a toward the fixing roller 100. When the recording paper P is transported to the fixing roller 100 side beyond the boundary indicated by the alternate long and short dash line b due to the adhesive force of the melted toner T, the recording paper P is wound around the fixing roller 100.

  Here, the adhesion force of the melted toner to the fixing roller is F1, and the bending force required to wind the recording paper (the force required to bend the recording paper from the one-dot chain line a to the one-dot chain line b by an angle θ) is F2. Then, when the relationship of F1 <F2 is satisfied, the recording paper can be separated from the fixing roller and carried out.

  Conventionally, in order to make it easier to separate the recording paper from the fixing roller, the toner adhesion force F1 is reduced by adding a release agent such as wax to the toner (for example, Patent Documents). 1). Further, in order to facilitate separation of the recording paper from the fixing roller, as shown by a two-dot chain line in FIG. 16, by reducing the diameter of the fixing roller, the boundary line where the winding occurs is changed from the one-dot chain line b to the one-dot chain line b. There is also a method of increasing the bending force F2 required for winding the recording paper by changing to the position '.

  However, even if the adhesion force of the toner is reduced or the diameter of the fixing roller is reduced as described above, if the recording paper having a small bending rigidity (stiffness) such as a thin paper is used, the recording paper is wound. Since the bending force F2 required for this is reduced, winding around the fixing roller may occur.

  In view of such circumstances, the inventors of the present invention, first, a fixing device capable of improving the separation property of the recording medium by improving the bending rigidity of the recording medium, and an image forming apparatus including the fixing device. Proposed.

In this fixing device, both the fixing roller and the pressure roller have a wave shape, and when the toner on the recording paper is fixed using this, the winding of the recording paper around the fixing roller is sufficiently improved. It was proved.
However, on the other hand, a new technical problem has occurred that some gloss unevenness still appears in the fixed image due to the wavy shape of the roller.

  Therefore, according to the present invention, even when the proposed fixing device and the image forming apparatus including the fixing device are used, the separation of the recording medium is improved and the gloss unevenness of the fixed image is suppressed as much as possible. The present invention provides a method, a process cartridge useful for carrying out the method, and an image forming apparatus.

As a result of further studies, the present inventors have determined that the toner has a volume average particle size of 1.0 to 5.0 μm and a shape change rate of 10% or less at 200 ° C. and 0.03 N / mm ^2. By using the toner containing the coarse particles (filler), the gloss unevenness of the fixed image was successfully reduced and the present invention was achieved.

That is, the above-described problems are solved by the following inventions (1) to (19).
(1) In an image forming method including a step of fixing an unfixed toner image formed using toner on a support using a contact heating type fixing device,
The fixing device includes a fixing roller heated by a heating source, and a pressure roller disposed in pressure contact with the fixing roller, and a fixing nip formed by pressure-contacting the fixing roller and the pressure roller. The unfixed toner image on the recording medium is fixed to the recording medium by passing the recording medium through
The fixing roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and each reverse crown portion whose outer peripheral surface is formed in a reverse crown shape,
The pressure roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and one reverse crown portion whose outer peripheral surface is formed in a reverse crown shape, and
The crown portion of the fixing roller and the reverse crown portion of the pressure roller are made to correspond to each other, and the reverse crown portion of the fixing roller and the crown portion of the pressure roller are made to correspond to each other. A fixing device in which the pressure rollers are pressed against each other,
The toner contains at least a colorant, a resin, and roughness particles, and the roughness particles have a volume average particle size of 1.0 to 5.0 μm, 200 ° C., 0.03 N / mm ² , 1 The shape change rate (X) represented by the following formula (1) in minutes is a filler of 10% or less,
An image forming method.
X (%) = {(A−B) / A} × 100 (1)
However, the circularity before pressure treatment is A, and the circularity B after pressure treatment is B.
(2) In the fixing device, the crown disposed in correspondence with the fixing roller and the pressure roller when the crown portion and the reverse crown portion are arranged in contact with each other in an unloaded state. The image forming method according to (1), wherein a gap is not generated between the portion and the reverse crown portion.
(3) The image forming apparatus according to (1) or (2), wherein the fixing device is configured such that the crown portion and the reverse crown portion of each of the fixing roller and the pressure roller are continuously formed in an axial direction. Method.
(4) The fixing roller and the pressure roller have an elastic layer, and the fixing roller and the pressure roller are arranged with the crown portion and the reverse crown portion in contact with each other in an unloaded state. When it is provided, the sum of the thicknesses of the elastic layers of the fixing roller and the pressure roller in an arbitrary cross section in the axial direction is set to be constant, according to any one of (1) to (3). Image forming method.
(5) Any one of (1) to (4), wherein the crown portion and the reverse crown portion are disposed over a portion of the fixing roller and the pressure roller corresponding to at least the entire maximum passage width of the recording medium. An image forming method according to claim 1.
(6) Any one of (1) to (5), wherein the crown portion and the reverse crown portion are disposed in a portion corresponding to a part of the maximum passage width of the recording medium of the fixing roller and the pressure roller. The image forming method described in 1.
(7) (1) to (6) in which a linear portion is formed in at least one of the crown portion and the reverse crown portion of the fixing roller and at least one of the crown portion and the reverse crown portion of the pressure roller. The image forming method according to any one of the above.
(8) In a load state in which the fixing roller and the pressure roller are pressed against each other, a height difference between the top of the crown portion and the bottom of the reverse crown portion in the fixing nip is 0.16 mm or more and 0 The image forming method according to any one of (1) to (7), which is set to 8 mm or less.
(9) The fixing roller and the pressure roller are configured by covering an outer peripheral surface of a core material with an elastic layer, and the thickness of at least one of the core material and the elastic layer is set in an axial direction. The image forming method according to any one of (1) to (8), wherein the crown portion and the inverted crown portion are formed by being changed over.
(10) The fixing roller is constituted by a roller having no elastic layer on the outer peripheral surface of the core material, and the outer peripheral surface of the core material of the fixing roller is curved in the axial direction, thereby The image forming method according to any one of (1) to (3), wherein the reverse crown portion is formed.
(11) The pressure roller is configured by covering an outer peripheral surface of a core material with an elastic layer, and the outer peripheral surface of the core material of the pressure roller is curved in the axial direction. The image forming method according to (10), wherein the crown portion and the reverse crown portion are formed.
(12) The axial end portions of the fixing roller and the pressure roller on the same side in the axial direction are positioned in the axial direction and opposite to the positioned end portions of the fixing roller and the pressure roller. The image forming method according to any one of (1) to (11), wherein the side end portion is configured to be displaceable in the axial direction.
(13) In an image forming method including a step of fixing a toner image formed using a toner containing at least a resin and a colorant on a support using a contact heating type fixing device.
The fixing device includes a fixing roller heated by a heating source, an endless pressure belt, and a pressing member that presses an inner peripheral surface of the pressure belt and presses the pressure belt against the fixing roller. And fixing the unfixed image on the recording medium to the recording medium by passing the recording medium through a fixing nip formed by press-contacting the fixing roller and the pressure belt.
The fixing roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and each reverse crown portion whose outer peripheral surface is formed in a reverse crown shape,
The pressing surface of the pressing member that presses the pressure belt has at least one each of a convex surface portion formed in a convex shape and a concave surface portion formed in a concave shape,
The crown portion of the fixing roller and the concave surface portion of the pressing member are arranged in correspondence with each other, the reverse crown portion of the fixing roller and the convex surface portion of the pressing member are arranged in correspondence with each other, and A fixing device, wherein the pressing belt is pressed by a pressing member, and the fixing roller and the pressing belt are pressed against each other;
The toner contains at least a colorant, a resin, and roughness particles, and the roughness particles have a volume average particle size of 1.0 to 5.0 μm, 200 ° C., 0.03 N / mm ² , 1 The shape change rate (X) represented by the following formula (1) in minutes is a filler of 10% or less,
An image forming method.
X (%) = {(A−B) / A} × 100 (1)
However, the circularity before pressure treatment is A, and the circularity B after pressure treatment is B.
(14) The image forming method according to any one of (1) to (13), wherein the material of the roughness particles is one or more fillers selected from a resin, a metal oxide, or an inorganic oxide. .
(15) The image forming method according to any one of (1) to (14), wherein the roughness particles are colorless or have the same color as the colorant.
(16) The image forming method according to any one of (1) to (15), wherein the roughness particles contained in the toner are 1.0 to 70 parts by mass with respect to 100 parts by mass of the colored resin particles.
(17) The image forming method according to any one of (1) to (16), wherein the toner has a softening point of 110 ° C to 140 ° C.
(18) A process cartridge that includes at least an image carrier, a developing unit, and a fixing unit, and is detachable from an image forming apparatus. The developing unit includes any one of (1) to (17). A process cartridge in which toner is stored and the fixing device according to any one of (1) to (17) is used as the fixing unit.
(19) An image forming apparatus comprising the process cartridge according to (18).

  According to the present invention, when the recording medium is carried out of the fixing device, the apparent rigidity of the recording medium can be improved and the recording medium can be prevented from being wound around the fixing roller. Accordingly, it is possible to suppress the occurrence of problems such as jamming of the recording medium, and to provide a highly reliable fixing device and image forming apparatus. Further, according to the present invention, variation in contact pressure at the fixing nip can be suppressed. Thereby, it is possible to suppress the occurrence of uneven glossiness and the like in the fixed image, and it is possible to maintain good image formation. Furthermore, according to the present invention, by using the specific toner, it is possible to further suppress occurrence of uneven glossiness or the like in a fixed image. In addition, the following effects can also be obtained.

According to the invention of (1), the crown portion of the fixing roller and the reverse crown portion of the pressure roller are made to correspond to each other, and the reverse crown portion of the fixing roller and the crown portion of the pressure roller are made to correspond to each other. Since the pressure roller is in pressure contact, the fixing nip is curved. When the image is fixed, the recording medium enters a curved state due to the recording medium entering the curved fixing nip. In this way, by curving the recording medium, the apparent rigidity of the recording medium can be improved and carried out from the fixing nip. When the recording medium is carried out from the fixing nip, the recording medium is wound around the fixing roller. It becomes possible to suppress sticking.
Further, by causing the fixing roller and the pressure roller to be in pressure contact with each other so that the crown portion and the reverse crown portion correspond to each other, it is possible to suppress variation in contact pressure at the fixing nip. As a result, problems such as occurrence of uneven glossiness in the fixed image can be suppressed, and good image formation can be realized.
Further, by forming an image with toner containing roughness particles (fillers) having a shape change rate of 10% or less, uniform irregularities are formed on the image surface after fixing, and gloss unevenness can be further eliminated.

  According to the invention of (2), when the fixing roller and the pressure roller are brought into contact with each other in a no-load state, if there is a gap between the corresponding crown portion and the reverse crown portion, When the pressure roller is brought into contact with the pressure roller, a pressure unevenness occurs in the fixing nip in the axial direction, and image noise may occur. Therefore, as described above, when the fixing roller and the pressure roller are brought into contact with each other in an unloaded state, by preventing a gap from being generated between the corresponding crown portion and the reverse crown portion, image noise is reduced. Occurrence can be suppressed and separation of the recording paper can be ensured.

  According to the invention of (3), by forming the crown portion and the reverse crown portion continuously in the axial direction, it is possible to suppress the occurrence of wrinkles on the recording medium and to ensure the separation of the recording paper. be able to.

  According to the invention of the above (4), when the fixing roller and the pressure roller are brought into contact with each other in an unloaded state, the sum of the elastic layers of the respective rollers is made constant so that the fixing roller and the pressure roller The pressure peak value in the rotation direction can be made constant over the axial direction. Thereby, pressure unevenness in the fixing nip can be suppressed, and generation of image noise can be suppressed.

  According to the invention of (5), the recording medium is curved by disposing the crown portion and the reverse crown portion over at least a portion of the fixing roller and the pressure roller corresponding to the entire maximum passing width of the recording medium. Thus, the recording medium can be carried out from the fixing nip, and the winding of the recording medium around the fixing roller can be suppressed.

  According to the invention of (6), the recording medium is curved by disposing the crown portion and the reverse crown portion in a portion corresponding to a part of the maximum passage width of the recording medium of the fixing roller and the pressure roller. Thus, the recording medium can be carried out from the fixing nip, and the winding of the recording medium around the fixing roller can be suppressed.

  According to the invention of (7), it is possible to form a straight line portion in at least one of the crown portion and the reverse crown portion.

  According to the invention of (8), when the fixing roller and the pressure roller are in pressure contact with each other, the height difference between the top of the crown portion and the bottom of the reverse crown portion in the fixing nip is less than 0.16 mm. The amount of bending of the recording medium is reduced at the fixing nip, and there is a possibility that the apparent rigidity of the recording medium necessary for separating the recording medium cannot be obtained. Therefore, by setting the height difference between the top of the crown portion and the bottom of the reverse crown portion to be 0.16 mm or more, the apparent rigidity of the recording medium is sufficiently secured and the winding of the recording medium around the fixing roller is ensured. Can be suppressed. On the other hand, if the height difference between the top of the crown portion and the bottom of the reverse crown portion in the fixing nip exceeds 0.8 mm in the above load state, the difference in rotational speed between the crown portion and the reverse crown portion increases, and the recording medium is wrinkled. May occur. Therefore, by setting the height difference between the top portion of the crown portion and the bottom portion of the reverse crown portion to be 0.8 mm or less, it is possible to carry out the recording medium without generating wrinkles, and to perform good image formation. it can.

  According to the invention of (9), the crown portion and the reverse crown portion are formed on the outer peripheral surface of the fixing roller and the pressure roller by changing the thickness of at least one of the core material and the elastic layer in the axial direction. Is possible.

  According to the invention (10), even when the fixing roller as described above is applied, the fixing nip can be curved, so that it is possible to ensure the separation of the recording paper.

  According to the invention of (11), the fixing nip can be sufficiently formed by pressing the pressure roller having the elastic layer against the fixing roller not having the elastic layer. As a result, the occurrence of image noise can be suppressed, and the separation of the recording paper can be ensured. Further, in the pressure roller, it is possible to make the thickness of the elastic layer constant in the axial direction by curving the outer peripheral surface of the core material to form the crown portion and the reverse crown portion. The pressure peak value in the rotation direction of the fixing roller and the pressure roller can be made constant over the axial direction. Thereby, pressure unevenness in the fixing nip can be suppressed, and generation of image noise can be suppressed.

  According to the invention of (12), the end portions on the same axial direction of the fixing roller and the pressure roller are positioned in the axial direction, and the positioned end portions of the fixing roller and the pressure roller are respectively positioned. By configuring the opposite end to be axially displaceable, the fixing roller and the pressure roller can be extended (displaced) to the same end in the axial direction even if the fixing roller is extended due to thermal expansion. Is possible. Thereby, it is possible to suppress the positional deviation between the crown portion and the reverse crown portion, and it is possible to suppress the variation in the contact pressure at the fixing nip.

According to the invention of (13), the crown portion of the fixing roller and the concave surface portion of the pressing member are arranged in correspondence with each other, and the reverse crown portion of the fixing roller and the convex surface portion of the pressing member are arranged in correspondence with each other. Since the fixing roller and the pressure belt are pressed against each other, the fixing nip is formed to be curved. In this case as well, the recording medium can be curved by intruding the recording medium into the fixing nip, and the apparent rigidity of the recording medium can be improved and carried out of the fixing nip as in the first aspect of the invention. be able to. Thereby, it is possible to suppress the recording medium from being wound around the fixing roller when the recording medium is carried out of the fixing nip.
Also, since the crown portion and the concave surface portion are made to correspond and the reverse crown portion and the convex surface portion are made to correspond so that the fixing roller and the pressure belt are pressed against each other, the contact pressure variation in the fixing nip is similar to the invention of (1). Can be suppressed. As a result, problems such as occurrence of uneven glossiness in the fixed image can be suppressed, and good image formation can be realized.

  According to the invention of (14), since the material of the coarse particles contained in the toner is a filler selected from a resin, a metal oxide or an inorganic oxide, it is possible to further reduce gloss unevenness of a fixed image. Can do.

  According to the invention of (15), a good quality single color image and full color image can be obtained by making the coarse particles colorless or similar to the color of the toner colorant.

  According to the invention (16), since the ratio of the roughness particles contained in the toner is 1.0 to 70% by mass in the total amount of the toner, a uniform gloss can be obtained in the fixed image.

  According to the invention (17), since the softening point of the toner is 110 ° C. to 140 ° C., the toner can be fixed without any trouble.

  According to the invention of (18), image formation can be easily performed by using this process cartridge.

  According to the invention (19), image formation can be easily performed by using this image forming apparatus.

1 is a schematic diagram illustrating an overall configuration of a color image forming apparatus of the present invention. 1 is a schematic diagram of a fixing device according to Embodiment 1 of the present invention. 1 is a cross-sectional view of a fixing roller according to Embodiment 1 of the present invention. It is sectional drawing of the pressure roller which concerns on Example 1 of this invention. It is sectional drawing of the said fixing roller and the said pressure roller. It is a schematic diagram for demonstrating the amplitude and height difference of a crown part and a reverse crown part. It is sectional drawing of the fixing roller and pressure roller which concern on Example 2 of this invention. It is sectional drawing of the fixing roller and pressure roller which concern on Example 3 of this invention. It is sectional drawing of the modification of the fixing roller and pressure roller which concern on Example 3 of this invention. It is sectional drawing of the fixing roller and pressure roller which concern on Example 4 of this invention. FIG. 10 is a schematic diagram of a fixing device according to a fifth embodiment of the present invention. It is sectional drawing of the fixing roller which concerns on Example 5 of this invention, a pressure belt, and a press member. It is a figure for demonstrating the measuring method of the apparent rigidity of a recording paper. 6 is a graph showing the relationship between the number of curvatures of the fixing nip and the apparent rigidity of the recording paper. It is a graph which shows the test result which compares the separation property of a recording paper, Comprising: (A) shows a test result in case only one crown part and a reverse crown part are shown, (B) shows a crown part and a reverse crown. The test result in the case of having one part each is shown. FIG. 6 is a diagram for explaining an operation in which a recording sheet is wound around a fixing roller.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated based on drawing. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of an embodiment of the present invention, and does not limit the scope of the claims.

  First, a fixing device and an image forming apparatus including the fixing device, which are characteristic parts of the present invention, will be described.

  FIG. 1 is a schematic configuration diagram showing a color image forming apparatus according to the present invention. An image forming apparatus 1 of the present invention shown in FIG. 1 is a tandem type color printer. Four toner bottles 2Y, 2M, 2C, and 2K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably (replaceable) in the bottle housing portion 2 above the main body of the image forming apparatus 1. is set up. An intermediate transfer unit 3 is disposed below the bottle housing portion 2. Image forming units 4Y, 4M, 4C, and 4K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 30 of the intermediate transfer unit 3.

  In each of the image forming units 4Y, 4M, 4C, and 4K, photosensitive drums 5Y, 5M, 5C, and 5K are disposed as image carriers. Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 6, a developing unit 7, a cleaning unit 8, a charge eliminating unit (not shown), and the like are disposed. Then, an image forming process (charging process, exposure process, development process, transfer process, cleaning process) is performed on each of the photoconductive drums 5Y, 5M, 5C, and 5K. An image of each color is formed on 5K.

  The photosensitive drums 5Y, 5M, 5C, and 5K are rotationally driven in a clockwise direction in FIG. 1 by a drive motor (not shown). Then, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged at the position of the charging unit 6 (charging process). Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser beam emitted from the exposure unit 3, and electrostatic latent images corresponding to the respective colors are formed by exposure scanning at this position. (Exposure process).

  Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the developing unit 7, and the electrostatic latent image is developed at this position to form toner images of each color (development process). ). Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach the positions facing the intermediate transfer belt 30 and the first transfer bias rollers 31Y, 31M, 31C, and 31K, and at these positions, the photoconductive drums 5Y, 5M. The toner images on 5C and 5K are transferred onto the intermediate transfer belt 30 (primary transfer step). At this time, a small amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

  Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning unit 8, and untransferred toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K is removed from the cleaning unit 8 at this position. 8 is mechanically collected by a cleaning blade (cleaning step). Finally, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing a neutralization unit (not shown), and the residual potential on the photosensitive drums 5Y, 5M, 5C, and 5K is removed at this position. . Thus, a series of image forming processes performed on the photosensitive drums 5Y, 5M, 5C, and 5K is completed.

  Thereafter, the toner images of the respective colors formed on the photosensitive drums 5Y, 5M, 5C, and 5K through the developing process are transferred onto the intermediate transfer belt 30 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 30. The intermediate transfer unit 3 includes an intermediate transfer belt 30, four primary transfer bias rollers 31Y, 31M, 31C, and 31K, a secondary transfer backup roller 32, a cleaning backup roller 33, a tension roller 34, and an intermediate transfer cleaning unit 35. Etc. The intermediate transfer belt 30 is stretched and supported by three rollers 32 to 34 and is endlessly moved in the direction of the arrow in FIG.

  The four primary transfer bias rollers 31Y, 31M, 31C, and 31K respectively sandwich the intermediate transfer belt 30 between the photosensitive drums 5Y, 5M, 5C, and 5K to form a primary transfer nip. Then, a transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 31Y, 31M, 31C, and 31K. The intermediate transfer belt 30 travels in the direction of the arrow, and sequentially passes through the primary transfer nips of the primary transfer bias rollers 31Y, 31M, 31C, and 31K. In this way, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are primarily transferred while being superimposed on the intermediate transfer belt 30.

  Thereafter, the intermediate transfer belt 30 onto which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 36. At this position, the secondary transfer backup roller 32 sandwiches the intermediate transfer belt 30 between the secondary transfer roller 36 and forms a secondary transfer nip. The four-color toner images formed on the intermediate transfer belt 30 are transferred onto a recording sheet P as a recording medium conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording paper P remains on the intermediate transfer belt 30. Thereafter, the intermediate transfer belt 30 reaches the position of the intermediate transfer cleaning unit 35. At this position, the untransferred toner on the intermediate transfer belt 30 is collected. Thus, a series of transfer processes performed on the intermediate transfer belt 30 is completed.

  Here, the recording sheet P conveyed to the position of the secondary transfer nip is fed from the sheet feeding unit 10 disposed below the main body of the image forming apparatus 1 via the sheet feeding roller 11 and the registration roller pair 12. It has been transported. Specifically, a plurality of recording papers P are stored in the paper supply unit 10 in a stacked manner. When the paper feed roller 11 is driven to rotate counterclockwise in FIG. 1, the uppermost recording paper P is fed between the rollers of the registration roller pair 12.

  The recording paper P conveyed to the registration roller pair 12 is temporarily stopped at the position of the roller nip of the registration roller pair 12 that has stopped rotating. Then, the registration roller pair 12 is rotationally driven in synchronization with the color image on the intermediate transfer belt 30, and the recording paper P is conveyed toward the secondary transfer nip. Thus, a desired color image is transferred onto the recording paper P.

  Thereafter, the recording paper 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 27. The fixing device 27 includes, for example, a fixing roller 61 and a pressure roller 62, and the recording sheet P is carried into the fixing nip where the fixing roller 61 and the pressure roller 62 are in pressure contact, whereby the color transferred to the surface is transferred. The image is fixed on the recording paper P. Thereafter, the recording paper P is discharged out of the apparatus through the rollers of the paper discharge roller pair 13. The recording paper P discharged out of the apparatus by the paper discharge roller pair 13 is sequentially stacked on the stack unit 14 as an output image. Thus, a series of image forming processes in the image forming apparatus is completed.

  Hereinafter, the configuration of the fixing device 27 which is a characteristic part of the present invention will be described.

[Configuration Example 1 of Fixing Device]
FIG. 2 shows a configuration of a fixing device according to Configuration Example 1 of the present invention. As shown in FIG. 2, the fixing device 27 includes a fixing roller 61 and a pressure roller 62 disposed in pressure contact with the fixing roller 61. A fixing nip N is formed at a location where the fixing roller 61 and the pressure roller 62 are pressed against each other.

  The fixing roller 61 includes a metal core member 611 formed in a cylindrical shape, an elastic layer 612 that covers the outer peripheral surface of the core member 611, and a release layer 613 that covers the outer peripheral surface of the elastic layer 612. . Inside the core material 611, a heating source 63 such as a heater lamp is disposed in the axial direction, and the fixing roller 61 is heated when the heating source 63 generates heat. In addition, a temperature detection device 64 that detects the surface temperature of the fixing roller 61 is disposed around the fixing roller 61. A control device (not shown) is configured such that the surface temperature of the fixing roller 61 becomes a predetermined fixing temperature by controlling the amount of heat generated by the heating source 63 based on the surface temperature of the fixing roller 61 detected by the temperature detecting device 64. Has been. The pressure roller 62 includes a metal core member 621 formed in a cylindrical shape, an elastic layer 622 that covers the outer peripheral surface of the core member 621, and a release layer 623 that covers the outer peripheral surface of the elastic layer 622. Have.

  FIG. 3 is a cross-sectional view of the fixing roller 61 cut in the axial direction. In FIG. 3, the same reference numerals as those shown in FIG. 2 denote the same members as those shown in FIG. As shown in FIG. 3, the fixing roller 61 has at least one crown portion 61a whose outer peripheral surface is formed in a crown shape and one reverse crown portion 61b whose outer peripheral surface is formed in a reverse crown shape. Yes. In this case, a plurality of crown portions 61a and a plurality of reverse crown portions 61b are alternately and continuously arranged in the axial direction on the fixing roller 61, and the outer peripheral surface of the fixing roller 61 undulates in the axial direction as a whole. It is formed as follows. The “crown shape” refers to a shape in which the roller diameter decreases toward both ends in the axial direction, and the “reverse crown shape” refers to a shape in which the roller diameter increases toward both ends in the axial direction. I mean.

  Further, as shown in FIG. 3, the elastic layer 612 and the release layer 613 of the fixing roller 61 are each formed to have a uniform thickness in the axial direction. On the other hand, the thickness of the core material 611 is formed so as to change in the axial direction. In this way, the core member 611 whose thickness is changed in the axial direction is covered with the elastic layer 612 and the release layer 613 having a uniform thickness, thereby forming the crown portion 61a and the reverse crown portion 61b on the fixing roller 61. is doing.

  As a method of covering the core material 611 with the corrugated outer peripheral surface as described above, the elastic layer 612 is covered with the core material 611, or the outer periphery of the core material 611. A method of forming the elastic layer 612 by applying an elastic material to the surface can be employed. Further, as the method for coating the release layer 613 on the elastic layer 612, the same method as the method for coating the elastic layer 612 can be employed.

  FIG. 4 is a cross-sectional view of the pressure roller 62 cut in the axial direction. In FIG. 4, the same reference numerals as those shown in FIG. 2 denote the same members as those shown in FIG. As shown in FIG. 4, the pressure roller 62 has at least one crown portion 62a whose outer peripheral surface is formed in a crown shape and one reverse crown portion 62b whose outer peripheral surface is formed in a reverse crown shape. ing. Also in the pressure roller 62, the plurality of crown portions 62a and the plurality of reverse crown portions 62b are alternately and continuously arranged in the axial direction, and the outer peripheral surface of the pressure roller 62 is axially as a whole. It is formed to wave. Here, “crown shape” and “reverse crown shape” mean the same as above.

  As shown in FIG. 4, the elastic layer 622 and the release layer 623 of the pressure roller 62 are each formed to have a uniform thickness in the axial direction. On the other hand, the thickness of the core material 621 is formed so as to change in the axial direction. In this way, the core member 621 whose thickness is changed in the axial direction is coated with the elastic layer 622 and the release layer 623 having a uniform thickness, whereby the crown portion 62a and the reverse crown portion 62b are provided on the pressure roller 62. It is composed.

  The method for coating the elastic layer 622 on the core material 621 whose outer peripheral surface of the pressure roller 62 is waved and the method for coating the release layer 623 on the elastic layer 622 have been described in the fixing roller 61. Since a method similar to the method can be employed, description thereof is omitted.

  3 and 4, the crown portions 61a and 62a and the reverse crown portions 61b and 62b are portions corresponding to the entire maximum passage width W of at least the recording medium (recording paper) of the fixing roller 61 and the pressure roller 62. However, the crown portions 61a and 62a and the reverse crown portions 61b and 62b may be provided only in a portion corresponding to a part of the maximum passage width W of the recording medium.

  FIG. 5 is a cross-sectional view in the axial direction in a state where the fixing roller 61 and the pressure roller 62 according to Configuration Example 1 are in pressure contact with each other. In this figure, means for pressing the pressure roller 62 against the fixing roller 61 is not shown. As shown in FIG. 5, the crown portion 61a of the fixing roller 61 and the reverse crown portion 62b of the pressure roller 62 are made to correspond to each other, and the reverse crown portion 61b of the fixing roller 61 and the crown portion 62a of the pressure roller 62 are made to correspond to each other. The fixing roller 61 and the pressure roller 62 are in pressure contact with each other.

  The number of crown portions 61a and 62a and reverse crown portions 61b and 62b included in the fixing roller 61 and the pressure roller 62 is not particularly limited as long as it is one or more. However, in a state where the fixing roller 61 and the pressure roller 62 are in pressure contact with each other, the numbers of the respective crown portions 61a and 62a are matched so that all the reverse crown portions 61b and 62b can correspond to each other. Yes.

  In addition, it is preferable that the crown portions 61a and 62a and the reverse crown portions 61b and 62b corresponding to the fixing roller 61 and the pressure roller 62 are formed in a shape matching each other. In other words, when the pressing force is not applied to the fixing roller 61 and the pressure roller 62 (in a no-load state), the gap is not generated between the corresponding crown portion and the reverse crown portion. It is preferable to do. If the fixing roller 61 and the pressure roller 62 are brought into contact with each other in an unloaded state, and there is a gap between the corresponding crown portion and the reverse crown portion, the rollers 61 and 62 are pressed against each other and the load is applied. This is because when the state is set, pressure unevenness occurs in the fixing nip N in the axial direction, and image noise may occur. Specifically, when the axial cross section of the outer peripheral surface of one of the fixing roller 61 and the pressure roller 62 has a sin curve shape (sinusoidal shape), the axial cross section of the other outer peripheral surface is the sin curve shape. Are formed in a sin curve shape (inverse sinusoidal shape) with the same amplitude and the same period length but with an opposite phase. It should be noted that the range in which the gap does not occur should be at least over the maximum passage width of the recording medium. It is also possible to form the rollers 61 and 62 in a curved shape other than the sin curved shape.

  Further, in the state where the fixing roller 61 and the pressure roller 62 are disposed in a state where the crown portion and the reverse crown portion are in contact with each other in an unloaded state, the sum of the thicknesses of the respective elastic layers at arbitrary positions in the axial direction is It is desirable to set it to be constant. If the sum of the thicknesses of these elastic layers is not constant, the pressure peak values in the rotation direction of the rollers 61 and 62 are different in the axial direction, causing pressure non-uniformity in the fixing nip and causing image noise. It is.

  FIG. 6 is an enlarged view of the crown portions 61 a and 62 a and the reverse crown portions 61 b and 62 b of the fixing roller 61 or the pressure roller 62. In FIG. 6, symbol S1 indicates the height (amplitude) at the top Q of the crown portions 61a and 62a, and symbol S2 indicates the height (amplitude) at the bottom U of the reverse crown portions 61b and 62b. Moreover, the code | symbol H in the figure has shown the height difference of the top part Q of crown part 61a, 62a and the bottom part U of reverse crown part 61b, 62b.

  In the present invention, in the load state in which the fixing roller 61 and the pressure roller 62 are in pressure contact with each other, the height difference H between the crown portion and the reverse crown portion in the fixing nip N is 0.16 mm or more and 0.8 mm or less. It is desirable to set. The reason why it is desirable to set the height difference H in this way will be described in detail in the following description of the operation and effect of the present invention.

  In the loaded state, the elastic layer of each of the rollers 61 and 62 is compressed, so that the difference in height is smaller than in the unloaded state where the rollers 61 and 62 are not pressed against each other. Generally, in the fixing roller 61 and the pressure roller 62, when the compressibility of the elastic layer exceeds 20%, the elastic layer is plastically deformed, which causes generation of image noise and abnormal noise. Usually, it is set to be 20% or less. In the configuration example of the present invention, since the compression rate of the elastic layer is set to 20%, the height difference H when the rollers 61 and 62 are pressed against each other is 80% of the height difference H in the no-load state. It becomes. Therefore, the height difference H in the non-load state without pressure contact is set larger than the height difference H in the load state with pressure contact. Specifically, in the present invention in which the compressibility of the elastic layer is set to 20%, the height difference H in the unloaded state is 1.25 times the height difference in the loaded state (0.16 mm to 0.8 mm). Therefore, it is set within the range of 0.2 mm or more and 1 mm or less.

  In this configuration example, the height (amplitude) S1 of the crown portions 61a and 62a and the height (amplitude) S2 of the reverse crown portions 61b and 62b in the fixing roller 61 and the pressure roller 62 are set to the same value. Therefore, each of the heights S1 and S2 in the no-load state is set within a half of the height difference H (0.2 mm to 1 mm) in the no-load state. Therefore, each height S1, S2 in the no-load state is set within a range of 0.1 mm or more and 0.5 mm or less.

  As shown in FIG. 5, the fixing roller 61 and the pressure roller 62 include a plurality of bearings such as ball bearings between two side plates 71 and 72 disposed at a predetermined interval in the image forming apparatus. 73 is rotatably mounted via 73. Each bearing 73 is fixed to the side plates 71 and 72.

  A bearing 73 disposed at the left end portion of the fixing roller 61 in the figure is attached by being sandwiched between a stepped portion 74 formed on the outer periphery of the fixing roller 61 and a retaining ring 75. That is, the left end portion of the fixing roller 61 in the figure is positioned so as not to move in the axial direction. On the other hand, a bearing 73 disposed at the right end portion of the fixing roller 61 in the drawing is attached to the fixing roller 61 so as to be movable in the axial direction. Accordingly, the right end portion of the fixing roller 61 in the drawing can be displaced in the axial direction.

  A bearing 73 disposed at the left end of the pressure roller 62 in the drawing is attached by being sandwiched between a stepped portion 76 formed on the outer periphery of the pressure roller 62 and a retaining ring 77. That is, the left end portion of the pressure roller 62 in the figure is positioned so as not to move in the axial direction, like the fixing roller 61. On the other hand, a bearing 73 disposed at the right end of the pressure roller 62 in the drawing is attached to the pressure roller 62 so as to be movable in the axial direction. Accordingly, the right end portion of the pressure roller 62 in the figure is configured to be displaceable in the axial direction, like the fixing roller 61.

  In this way, the fixing roller 61 and the pressure roller 62 can position the end on the same side in the axial direction in the axial direction, and the end on the opposite side to the positioned end can be displaced in the axial direction. It is comprised so that it may become. The positioning end or the displaceable end may be either end as long as it is the end on the same side of the fixing roller 61 and the pressure roller 62.

[Configuration Example 2 of Fixing Device]
FIG. 7 shows a fixing roller 61 and a pressure roller 62 according to Configuration Example 2 of the present invention. As illustrated in FIG. 7, the fixing roller 61 and the pressure roller 62 according to the configuration example 2 are different from the fixing roller 61 and the pressure roller 62 according to the configuration example 1, and the thicknesses of the respective elastic layers 612 and 622 are set to the axis. It is changing across directions. On the other hand, the core materials 611 and 621 and the release layers 613 and 623 of the fixing roller 61 and the pressure roller 62 are formed to have uniform thicknesses. That is, in the configuration example 2, the crown portions 61a and 62a and the reverse crown portions 61b and 62b are formed on the fixing roller 61 and the pressure roller 62 by changing the thicknesses of the elastic layers 612 and 622 in the axial direction. is doing.

  In FIG. 7, the structure for attaching the fixing roller 61 and the pressure roller 62 to the image forming apparatus is not shown. Since the mounting structure of the rollers 61 and 62 according to the second embodiment and the configuration according to the second configuration example 2 are the same as those in the first configuration example of the present invention, the description thereof will be omitted.

  In the above configuration example 1 and configuration example 2 of the present invention, the thickness of one of the core materials 611 and 621 and the elastic layers 612 and 622 is changed in the axial direction. , 621 and the elastic layers 612 and 622 are changed in the axial direction so that the fixing roller 61 and the pressure roller 62 are provided with crown portions 61a and 62a and reverse crown portions 61b and 62b. Good (not shown).

[Configuration Example 3 of Fixing Device]
FIG. 8 shows a fixing roller 61 and a pressure roller 62 according to Configuration Example 3 of the present invention. In the configuration example 3, unlike the configuration examples 1 and 2 of the present invention, linear portions 61c and 62c are formed on the outer peripheral surfaces of the fixing roller 61 and the pressure roller 62, respectively. In this case, the straight portions 61 c and 62 c are formed in a part of each of the crown portion 61 a of the fixing roller 61 and the reverse crown portion 62 b of the pressure roller 62. Specifically, the linear portion 61c formed on the fixing roller 61 is disposed so as to constitute the top portion of the crown portion 61a, and the linear portion 62c formed on the pressure roller 62 constitutes the bottom portion of the reverse crown portion 62b. It is arranged to do. Further, the linear portions 61 c and 62 c are arranged so as to be parallel to the axial direction of the fixing roller 61 or the pressure roller 62.

  Further, the arrangement positions and orientations of the linear portions 61c and 62c are not limited to the configuration example shown in FIG. 8, and can be set to various arrangement positions and orientations. For example, as shown in FIG. 9, in the fixing roller 61 and the pressure roller 62, linear portions 61c and 62c are disposed between the curved portions of the crown portions 61a and 62a and the curved portions of the reverse crown portions 61b and 62b. And you may comprise so that these curve parts may be connected smoothly by the linear parts 61c and 62c.

  8 and 9, the thickness of at least one of the core materials 611 and 621 and the elastic layers 612 and 622 is set in the axial direction in the same manner as the configuration example 1 or the configuration example 2 of the present invention. It is possible to configure the crown portions 61a and 62a and the reverse crown portions 61b and 62b by changing the distance.

  Also, in the configuration example shown in FIGS. 8 and 9, the structure for attaching the fixing roller 61 and the pressure roller 62 to the image forming apparatus is not shown. Since the mounting structure of the rollers 61 and 62 according to the configuration example 3 and other configurations are the same as those in the configuration example 1 of the present invention, description thereof will be omitted.

[Fixing Device Configuration Example 4]
FIG. 10 shows a fixing roller 61 and a pressure roller 62 according to Configuration Example 4 of the present invention. The configuration example 4 is different from the configuration examples of the present invention described above, and the fixing roller 61 does not have an elastic layer. That is, the fixing roller 61 includes a cylindrical metal core 611 and a release layer 613 that covers the outer peripheral surface of the core 611. In this case, the outer peripheral surface of the core member 611 of the fixing roller 61 is curved in the axial direction to form the crown portion 61a and the reverse crown portion 61b.

  On the other hand, the pressure roller 62 has an elastic layer 622 in order to ensure a sufficient fixing nip N when pressed against the fixing roller 61. Note that the pressure roller 62 shown in FIG. 10 is configured by a roller having a core material 621, an elastic layer 622, and a release layer 623, similarly to the above-described configuration examples. In this case, the outer peripheral surface of the core member 621 of the pressure roller 62 is curved in the axial direction to form the crown portion 62a and the reverse crown portion 62b. It is also possible to form the crown portion 62a and the reverse crown portion 62b by forming the core material 621 straight and changing the thickness of the elastic layer 622 in the axial direction. However, in this case, since the thickness of the elastic layer 622 is not constant, the pressure peak values in the rotation direction of the rollers 61 and 62 are different in the axial direction, causing pressure unevenness in the fixing nip, which causes image noise. There is a fear. Therefore, as shown in FIG. 10, it is preferable to make the thickness of the elastic layer 622 constant over the axial direction.

  In FIG. 10, the structure for attaching the fixing roller 61 and the pressure roller 62 to the image forming apparatus is not shown. Since the mounting structure of the rollers 61 and 62 according to the configuration example 4 and the configuration according to the other configuration example 4 are the same as those in the configuration example 1 of the present invention, description thereof will be omitted.

[Fixing Device Configuration Example 5]
FIG. 11 shows a configuration of a fixing device according to Configuration Example 5 of the present invention. A fixing device 27 shown in FIG. 11 includes a fixing roller 61, a pressure belt 65, and a pressing member 66 that presses the inner peripheral surface of the pressure belt 65 and presses the pressure belt 65 against the fixing roller 61. A fixing nip N is formed at a location where the fixing roller 61 and the pressure belt 65 are pressed against each other.

  The fixing roller 61 includes a metal core 611 formed in a cylindrical shape, an elastic layer 612 that covers the outer peripheral surface of the core 611, and the same as the configuration example 1 of the present invention described in FIG. A release layer 613 that covers the outer peripheral surface of the elastic layer 612 is provided. A heating source 63 such as a heater lamp is disposed inside the fixing roller 61, and a temperature detection device 64 that detects the surface temperature of the fixing roller 61 is disposed around the fixing roller 61. is there.

  The pressure belt 65 is constituted by an endless belt member made of a polyimide film or the like. The pressure belt 65 is stretched around the pressing member 66 in a state where no tension is applied thereto, and is configured to rotate following the fixing roller 61. The pressing member 66 includes an elastic layer 661 made of silicon rubber or the like, and a holder 662 that holds the elastic layer 661. The holder 662 is urged toward the fixing roller 61 by an urging means such as a spring (not shown).

  FIG. 12 is an axial sectional view of the fixing roller 61 and the pressure roller 62 according to Configuration Example 5. As shown in FIG. 12, the fixing roller 61 according to Configuration Example 5 is configured in the same manner as the fixing roller 61 according to Configuration Example 1 of the present invention. Therefore, the fixing roller 61 shown in FIG. 12 has at least one crown portion 61a whose outer peripheral surface is formed in a crown shape and one reverse crown portion 61b whose outer peripheral surface is formed in a reverse crown shape. . Also in the fixing roller 61 according to the configuration example 5, the crown portion 61a and the reverse crown portion 61b can be configured by changing the thickness of at least one of the core material 611 and the elastic layer 612 in the axial direction. Is possible.

  On the other hand, the pressing member 66 has at least one convex surface portion 66 a formed in a convex shape and at least one concave surface portion 66 b formed in a concave shape on the pressing surface 660 that presses the pressure belt 65. In this case, a plurality of convex surface portions 66a and a plurality of concave surface portions 66b are alternately and continuously arranged in the longitudinal direction on the pressing surface 660, and the pressing surface 660 is formed so as to wave in the longitudinal direction as a whole. ing.

  In addition, as shown in FIG. 12, the pressing member 66 changes the thickness of the holder 662 in the longitudinal direction to form a convex surface portion 66a and a concave surface portion 66b on the pressing surface 660 of the pressing member 66. In addition, the convex surface portion 66a and the concave surface portion 66b are configured by changing the thickness of the elastic layer 661 in the longitudinal direction or by changing the thicknesses of both the elastic layer 661 and the holder 662 in the longitudinal direction. Is also possible.

  In FIG. 12, the convex surface portion 66a and the concave surface portion 66b are disposed over at least a portion of the pressing member 66 corresponding to the entire maximum passage width W of the recording medium, but the convex surface portion 66a and the concave surface portion 66b. May be disposed only in a portion corresponding to a part of the maximum passage width W of the recording medium.

  In a state where the pressure belt 65 is pressed against the fixing roller 61 by the pressing member 66, the crown portion 61 a of the fixing roller 61 and the concave surface portion 66 b of the pressing member 66 are arranged in correspondence with each other, and the reverse crown portion of the fixing roller 61 is arranged. 61b and the convex portion 66a of the pressing member 66 are arranged in correspondence with each other. When the pressure belt 65 is sandwiched between the fixing roller 61 and the pressing member 66 arranged as described above, the pressure belt 65 is formed to wave at the sandwiched portion. However, the pressure belt 65 has a flat surface at a location where the pressure belt 65 is released from the clamping between the fixing roller 61 and the pressing member 66.

  The number of crown portions 61a and reverse crown portions 61b included in the fixing roller 61 and the number of convex surface portions 66a and concave surface portions 66b included in the pressing member 66 are not particularly limited as long as the number is one or more. However, all the convex surface portions 66a and the concave surface portions 66b can be made to correspond to all the crown portions 61a and the reverse crown portions 61b in a state where the pressure belt 65 is pressed against the fixing roller 61 by the pressing member 66. The number of each is combined.

  Further, in the configuration example 5 of the present invention, the shapes of the crown portion 61a and the reverse crown portion 61b of the fixing roller 61 and the convex surface portion 66a and the concave surface portion 66b of the pressing member 66 are sin curve shapes, FIG. 8 or FIG. It is possible to form in the shape which has a linear part in a part as shown in FIG.

  In addition, it is preferable that the corresponding crown portion 61a and the concave surface portion 66b and the corresponding reverse crown portion 61b and the convex surface portion 66a are formed in a shape that matches each other. In other words, when the fixing roller 61 and the pressing member 66 are brought into contact with each other without applying a pressing force (in a no-load state), between the corresponding crown portion and the concave surface portion, and between the corresponding reverse crown portion and the convex surface portion, It is preferable to configure so that there is no gap between them. Specifically, when the axial cross section (or longitudinal cross section) of the outer peripheral surface of one of the fixing roller 61 and the pressing member 66 has a sin curve shape (sinusoidal shape), the axial direction ( (Or a longitudinal section) is formed in a sin curve shape (inverse sinusoidal shape) having the same amplitude and the same period length as the sin curve shape but having an opposite phase. It should be noted that the range in which the gap does not occur should be at least over the maximum passage width of the recording medium.

  Also in this configuration example, the thickness of each elastic layer at an arbitrary position in the axial direction in a state where the fixing roller 61 and the pressing member 66 are disposed in a state where the convex and concave portions are in contact with each other in an unloaded state. It is desirable to set the sum of to be constant.

  Similarly to the above configuration examples, in the load state in which the fixing roller 61 and the pressing member 66 are pressed against each other via the pressure belt 65, the height difference of the unevenness in the fixing nip N is 0.16 mm or more. Is preferably set to 0.8 mm or less. As in the above configuration example, when the compression rate of the elastic layer is set to 20% in the load state in which the pressing member 66 and the fixing roller 21 are in pressure contact, the height difference in the no-load state is the level of the load state. Since it is 1.25 times the difference (0.16 mm to 0.8 mm), it is set within the range of 0.2 mm or more and 1 mm or less.

  In FIG. 12, the attachment structure of the fixing roller 61 and the pressing member 66 to the image forming apparatus is not shown, but the fixing roller 61 and the pressing member 66 have end portions on the same side in the axial direction or the longitudinal direction. And the end opposite to each positioned end is configured to be displaceable in the axial direction or the longitudinal direction.

  Next, the toner which is a characteristic part of the present invention will be described.

The toner used in the image forming method of the present invention contains at least a colorant, a binder resin, and roughness particles, and the roughness particles have a volume average particle size of 1.0 to 5.0 μm and 200 ° C. 0.03 N / mm ² , and a filler having a shape change rate (X) represented by the above formula (1) per minute of 10% or less.

<Colorant>
In the toner of the present invention, a known colorant conventionally used in black toner and full color toner may be used. For example, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, duPont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 184, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Solvent Yellow 162, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment blue 15: 1, C.I. I. And CI Pigment Blue 15: 3.

  The content of the colorant in the toner particles is preferably in the range of 2 to 15 parts by mass with respect to 100 parts by mass of the total binder resin. It is preferable from the viewpoint of dispersibility that the colorant is used in the form of a masterbatch dispersed in a mixed binder resin of the first binder resin and the second binder resin used. The addition amount of the masterbatch may be an amount such that the amount of the colorant contained is within the above range. The colorant content in the masterbatch is preferably 20 to 40% by weight.

<Binder resin>
In the toner of the present invention, the type of binder resin is not particularly limited, and binder resins known in the field of black toner and full-color toner, for example, polyester resins, (meth) acrylic resins, styrene- (meth) acrylic resins. It may be a copolymer resin, epoxy resin, COC (cyclic olefin resin (for example, TOPAS-COC (manufactured by Ticona))), etc., but from the viewpoint of stress resistance in the developing device, a polyester resin is used. It is preferable to use it. The softening point of this binder resin is suitably 100 ° C to 150 ° C.

  As the polyester resin preferably used in the present invention, a polyester resin obtained by polycondensation of a polyhydric alcohol component and a polyvalent carboxylic acid component can be used.

  Among the polyhydric alcohol components, examples of the dihydric alcohol component include polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2- Bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane Bisphenol A alkylene oxide adducts such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanedio , 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, and the like.

  Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Is mentioned.

  Among the polyvalent carboxylic acid components, examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and succinic acid. , Adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, isooctenyl succinic acid, n-octyl succinic acid , Isooctyl succinic acid, anhydrides or lower alkyl esters of these acids.

  Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2 , 4-Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4- Examples include cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid, anhydrides of these acids, and lower alkyl esters.

  In the present invention, as a polyester resin, a polyester resin raw material monomer, a vinyl resin raw material monomer, and a mixture of monomers that react with both resin raw material monomers are used to obtain a polyester resin in the same container. A resin obtained by performing a condensation polymerization reaction and a radical polymerization reaction for obtaining a vinyl resin in parallel (hereinafter, simply referred to as “vinyl polyester resin”) can also be suitably used. In addition, the monomer which reacts with the raw material monomers of both resins is, in other words, a monomer that can be used for both the condensation polymerization reaction and the radical polymerization reaction. That is, it is a monomer having a carboxy group that can undergo a condensation polymerization reaction and a vinyl group that can undergo a radical polymerization reaction, and examples thereof include fumaric acid, maleic acid, acrylic acid, and methacrylic acid.

Examples of the raw material monomer for the polyester resin include the aforementioned polyhydric alcohol component and polyvalent carboxylic acid component.
Examples of the raw material monomer for the vinyl resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Styrene or styrene derivatives such as butylstyrene and p-chlorostyrene; Ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate , Isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, 3- (methyl) butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate Methacrylic acid alkyl esters such as decyl methacrylate, undecyl methacrylate, dodecyl methacrylate; methyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, acrylic Alkyl acrylates such as n-pentyl acid, isopentyl acrylate, neopentyl acrylate, 3- (methyl) butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, and dodecyl acrylate Esters; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid; acrylonitrile, maleic acid ester, itaconic acid ester, vinyl chloride, vinyl acetate, vinyl benzoate, vinylmethyl Examples include ethyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether.

  As a polymerization initiator when polymerizing the raw material monomer of the vinyl resin, for example, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1 Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, benzoyl peroxide, dicumyl peroxide, And peroxide polymerization initiators such as methyl ethyl ketone peroxide, isopropyl peroxycarbonate, lauroyl peroxide, and the like.

<Roughness particles>
The roughness particles must have a shape change rate (X) represented by the formula (1) at 200 ° C., 0.03 N / mm ² for 1 minute of 10% or less, preferably 5% or less. If this is not satisfied, it melts or collapses at the time of fixing, so that desired irregularities cannot be obtained.
The volume average particle diameter is 1.0 to 5.0 μm, preferably 2.0 to 3.0 μm. If the thickness is less than 1.0 μm, the toner image portion is embedded, so that unevenness cannot be obtained and uneven glossiness of the image cannot be eliminated. On the other hand, when the particle size is more than 5.0 μm, the coarse particles are easily removed from the toner image, and uniform unevenness cannot be obtained.
The addition amount of the roughness particles is 1.0 to 70 parts by mass, preferably 5.0 to 40 parts by mass with respect to 100 parts by mass of the colored resin particles (toner base particles composed of a colorant, a binder resin, and others). . When the amount is 1.0 part by mass or less, sufficient unevenness cannot be obtained in the image, and uneven glossiness of the image cannot be eliminated. On the other hand, when the amount is 70 parts by mass or more, the ratio of the coarse particles to the binder resin is too large, and the particles are separated without being sufficiently attached to the image, and uniform gloss cannot be obtained. It does not penetrate into the skin and good fixability cannot be obtained.

The material of the coarse particles is not particularly limited, but it is better that the environmental fluctuation is small, and resins, metal oxides, and inorganic oxides are preferable.
For example, examples of the resin include polyester, polyethylene, and polypropylene, and examples of the metal oxide or inorganic oxide include silicon oxide, titanium oxide, and aluminum oxide.

  The roughness particles are preferably colorless or similar in color to the toner colorant. For this reason, it is preferable that a resin is selected as the material for the coarse particles, and a colorant is added to the resin.

<Roughness particle shape change rate>
A sample with roughness particles sandwiched between two pieces of 200 mm x 200 mm glass is used as a measurement sample, and this measurement sample is set on the surface of a YS type test press (manufactured by Shinto Metal Industry Co., Ltd.). Then, the temperature was increased to 200 ° C. and then pressurized with 0.03 N / mm ² for 1 minute.
The shape change rate (X) was determined by the following equation (1).
X (%) = {(A−B) / A} × 100 (1)
However, the circularity before pressure treatment is A, and the circularity B after pressure treatment is B.

(Roughness particle diameter and circularity)
As a method for measuring the shape, an optical detection band method is suitable in which a suspension containing particles is passed through an imaging unit detection band on a flat plate, and a particle image is optically detected and analyzed by a CCD camera. A toner with an average circularity of 0.960 or more, which is a value obtained by dividing the perimeter of an equivalent circle having the same projected area obtained by this method by the perimeter of a real particle, produces a high-definition image having a reproducibility with an appropriate density. It was found to be effective in forming. More preferably, the average circularity is 0.980 to 1.000. This value is a value measured as an average circularity by a flow type particle image analyzer FPIA-2000. As a specific measuring method, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is obtained by performing dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser and measuring the shape and distribution of the toner with the above apparatus at a dispersion concentration of 3000 to 10,000 / μl. .

The roughness particles having a volume average particle diameter of 1.0 to 5.0 μm and a shape change rate (A) of 10% or less are made of a material such as resin, metal oxide or inorganic oxide as follows. Obtainable.
For example, when preparing roughness particles using a resin, desired roughness particles can be obtained by performing a treatment such as pulverizing the resin with a known pulverizer. Metal oxides and inorganic oxides can be used to obtain desired roughness particles in the same manner.

<Release agent>
The toner of the present invention can contain a release agent. There is no restriction | limiting in particular as a mold release agent, According to the objective, it can select suitably from well-known things, For example, waxes etc. are mentioned suitably. The melting point of the wax as the release agent is preferably 70 to 150 ° C. When the temperature is lower than 70 ° C., the heat resistant storage stability of the toner is inferior. When the temperature is higher than 150 ° C., the releasability cannot be sufficiently achieved and the toner fixing property is inferior. The amount of these release agents used is preferably 2 to 15% by weight based on the toner. If it is less than 2% by weight, the effect of preventing offset is insufficient, and if it exceeds 15% by weight, transferability and durability are deteriorated.

  A conventionally well-known thing can be used for the said wax. For example, low molecular weight polyethylene, low molecular weight polypropylene and other low molecular weight polyolefin waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, beeswax, carnauba wax, candelilla wax, rice wax, montan wax and other natural waxes, Examples include petroleum waxes such as paraffin wax and microcrystalline wax, higher fatty acids such as stearic acid, palmitic acid, and myristic acid, metal salts of higher fatty acids, higher fatty acid amides, synthetic ester waxes, and various modified waxes thereof. These waxes can be used alone or in combination of two or more.

  Of these, carnauba wax and its modified wax, polyethylene wax, and synthetic ester wax are preferably used. In particular, the synthetic ester wax pentaerythritol tetrabehenate is most preferred. The reason for this is that carnauba wax and its modified wax and synthetic ester wax are appropriately finely dispersed with respect to the polyester resin and polyol resin, so that the toner has excellent offset prevention, transferability and durability as described later. This is because it is easy.

<Charge control agent>
In the toner of the present invention, a known charge control agent conventionally used in full color toners may be used. The content of the charge control agent is appropriately determined according to desired charging characteristics, but is preferably 0.1 to 10% by weight, more preferably 0.2 to 5% by weight, based on the binder resin. . When the addition amount exceeds 10% by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is reduced, the image The concentration may decrease. On the other hand, if the addition amount is less than 0.1% by weight, the charge rising property and the charge amount are not sufficient, and the toner image may be easily affected.

  Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), Alkylamide, phosphorus simple substance 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 PSY VP2038, 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 (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo And pigments and other high molecular 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 toner of the present invention is obtained, for example, by mixing toner materials (colorant, binder resin, release agent, charge control agent, etc.), melting and kneading with a kneader, pulverizing and classifying to obtain toner base particles. The toner base particles are manufactured by adding coarse particles and, if necessary, inorganic fine particles and mixing them.

  For the mixing of the coarse particles and inorganic fine particles (external additives), a general powder mixer is used, but it is preferable to equip a jacket or the like to adjust the internal temperature. In order to change the load history applied to the additive (roughness particles, inorganic fine particles), the additive may be added in the middle or gradually. In this case, you may change the rotation speed, rolling speed, time, temperature, etc. of a mixer. Alternatively, a strong load may be applied first, then a relatively weak load, or vice versa. Examples of the mixing equipment that can be used include a V-type mixer, a rocking mixer, a Ladige mixer, a Nauter mixer, and a Henschel mixer. Next, the toner is obtained by passing through a sieve of 250 mesh or more to remove coarse particles and aggregated particles.

<External additive>
As the external additive used in the present invention, inorganic fine particles are preferably used for the purpose of imparting fluidity, chargeability and developability. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 ^-3 ~2μm, it is particularly preferably 5 × 10 ^-3 ~0.5μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The amount of the inorganic fine particles added is preferably 0.01 to 5 wt% of the image forming toner.

  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, silica sand, clay, mica, wollastonite, Examples thereof include diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  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. .

  The toner of the present invention preferably has a softening point of 110 ° C to 140 ° C. When the softening point of the toner is 110 ° C. or less, the toner is easily melted, so that the coarse particles are easily buried and uneven glossiness is difficult to be solved. On the other hand, if the temperature is 140 ° C. or higher, the toner viscosity at the time of fixing increases, so that the coarse particles are not sufficiently adhered and separation occurs. The softening point of the toner can be obtained as follows.

<Softening point>
Using a flow tester (CFT-500 / manufactured by Shimadzu Corporation), 1.5 g of a measurement sample is weighed, and using a die of H1.0 mm × φ1.0 mm, the heating rate is 3.0 ° C./min, and the preheating time is 180 seconds. The measurement was performed under the conditions of a load of 30 kg and a measurement temperature range of 30 to 160 ° C., and the temperature at which the sample flowed out 1/2 was taken as the softening point of the toner.

  The weight average particle diameter of the toner of the present invention is not particularly limited and can be appropriately selected according to the purpose. However, in order to obtain a high-quality image having excellent granularity, sharpness, and fine line reproducibility, the weight The average particle size is preferably 4 μm to 10 μm. The smaller the particle size, the better the image sharpness and fine line reproducibility. In particular, in a color image forming apparatus, the demand for image quality is strict and toner of 9 μm or less is required. In particular, 7 μm or less is preferable for image quality. On the other hand, if the toner particle size is too small, such as less than 4 μm, the toner fluidity and transferability deteriorate. Here, the weight average particle diameter of the toner can be obtained as follows.

<Toner particle size>
Examples of the measuring device for the particle size distribution of toner particles 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 the electrolytic aqueous 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 to 20 mg of the measurement sample is further added as a solid content. 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 (Dv) and the number average particle diameter (Dp) 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 of 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.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1]
(Creation of first binder resin)
As a vinyl monomer, 600 g of styrene, 110 g of butyl acrylate, 30 g of acrylic acid, and 30 g of dicumyl peroxide as a polymerization initiator were placed in a dropping funnel. Among polyester monomers, as polyols, 1230 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4 290 g of hydroxyphenyl) propane, 250 g of isododecenyl succinic anhydride, 310 g of terephthalic acid, 180 g of 1,2,4-benzenetricarboxylic anhydride and 7 g of dibutyltin oxide as esterification catalyst, thermometer, stainless steel stirrer, falling condenser and nitrogen Place in a 5 liter four-necked flask equipped with an introduction tube and stir at a temperature of 160 ° C. in a mantle heater under a nitrogen atmosphere, and mix the vinyl monomer resin and polymerization initiator mixture from the dropping funnel over an hour. And dripped. The addition polymerization reaction was aged for 2 hours while maintaining the temperature at 160 ° C., and then the temperature was raised to 230 ° C. to perform the condensation polymerization reaction. The degree of polymerization is tracked by the softening point measured using a constant load extrusion capillary rheometer, and when the desired softening point is reached, the reaction is terminated, and a resin H1 having a Tm (softening point) of 145 ° C. is obtained. It was.

(Creation of second binder resin)
As polyol, 2210 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 850 g of terephthalic acid, 120 g of 1,2,4-benzenetricarboxylic anhydride and dibutyltin oxide 0 as esterification catalyst .5 g was put into a 5 liter four-necked flask equipped with a thermometer, a stainless steel stirrer, a falling condenser and a nitrogen inlet tube, and the temperature was raised to 230 ° C. in a mantle heater under a nitrogen atmosphere to conduct a condensation polymerization reaction. It was. The degree of polymerization was monitored by the softening point measured using a constant load extrusion capillary rheometer, and when the desired softening point was reached, the reaction was terminated to obtain a resin L1 having a Tm of 110 ° C.

<Preparation of toner particles>
100 parts by mass of binder resin (60 parts by mass of first binder resin, 40 parts by mass of second binder resin) with respect to 100 parts by mass of C.I. I. After sufficiently mixing 8 parts by mass of a master batch corresponding to 4 parts by mass of Pigment Red 57-1, and 4 parts by mass of paraffin wax and 1.5 parts by mass of a boron charge control agent with respect to 100 parts by mass of toner using a Henschel mixer. Using a biaxial extrusion kneader (PCM-30: manufactured by Ikekai Tekko Co., Ltd.), melt kneading was performed. The obtained kneaded material was rolled to a thickness of 2 mm with a cooling press roller, cooled with a cooling belt, and then roughly pulverized with a feather mill. Then, after pulverizing with a mechanical pulverizer (KTM: Kawasaki Heavy Industries, Ltd.) to an average particle size of 10-12 μm and further pulverizing with a jet pulverizer (IDS: manufactured by Nippon Pneumatic Co., Ltd.) The fine powder classification is performed using a rotor type classifier (Teplex type classifier type: 100ATP: manufactured by Hosokawa Micron Corporation) to obtain magenta colored resin particles having a volume average particle size of 7.4 μm and a circularity of 0.91. It was.
To 100 parts by mass of the colored resin particles, 2.0 parts by mass of inorganic fine particles (TS530 manufactured by Cabogil) and 30 parts by mass of roughness particles (SiO ₂ having a volume average particle size of 1.5 μm) are added, and a Henschel mixer is added. To obtain magenta toner particles “Toner 1”.
In this embodiment, the coarse particles are mixed with the inorganic fine particles and adhered to the toner. However, they may be added at the time of mixing before kneading.

<Image formation by “Toner 1”>
Using an Ricoh ipsio C220, an unfixed image in which a solid image (adhesion amount 10 g / m ² ) was printed on the tip 5 mm with A4 longitudinal paper (type 6200Y paper made by Ricoh) was produced, and the tip 6 mm Cutting was performed to obtain a solid unfixed image with no margin at the tip. This unfixed image is obtained by using a roller as shown in FIG. 1 (fixed roller of an ipsio C220 manufactured by Ricoh Co., Ltd. (inner diameter 29.0 mm as a metal core 1, thickness 1.70 mm at the crown portion 2a, reverse crown). (The thickness of the portion 2b is 1.45 mm, the crown portion 2a is made of a sinusoidal core having a period of 60 mm, the elastic layer 3 is made of silicon rubber with a thickness of 1.70 mm, and the release layer is made of PFA) Further, the pressure roller is a roller as shown in FIG. 2 (inner diameter 29.0 mm as the metal core 5, thickness 1.70 mm at the crown 6 a, thickness 1.45 mm at the reverse crown 6 b, crown 6 a The aluminum core material is formed with a sin curve with a period of 60 mm, silicon rubber with a thickness of 1.70 mm as the elastic layer 7, and PFA as the release layer. Using the fixing device replaced with the above, the sheet was passed in a state where the rotation speed of the fixing roller of the fixing device was 6.8 rad / s and the surface temperature of the fixing roller was 160 ± 2 ° C.
The glossiness of the central portion in the vertical direction of the image after fixing was measured at intervals of 1 cm in the horizontal direction, and other evaluations were performed. The evaluation results are summarized in Table 1.

[Example 2]
“Toner 2” was prepared in the same manner as in Example 1, except that 70 parts by mass of the first binder resin of Example 1 was replaced with PP having a particle diameter of 3.0 μm and a mass part of 60 parts as coarse particles. Then, image formation was performed. The evaluation conditions and results are summarized in Table 1.

Example 3
“Toner 3” was prepared in the same manner as in Example 1 except that the first binder resin of Example 1 was replaced with 0 parts by mass and silicon dioxide having a particle size of 4.6 μm and 20 parts by mass as roughness particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

Example 4
“Toner 4” was prepared in the same manner as in Example 1 except that 100 parts by mass of the first binder resin of Example 1 was replaced with titanium dioxide having a particle size of 4.6 μm and 5 parts by weight as roughness particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

Example 5
“Toner 5” was prepared in the same manner as in Example 1 except that 80 parts by mass of the first binder resin of Example 1 was replaced with silicon dioxide having a particle size of 1.5 μm and a mass part of 0.8 parts as coarse particles. ”And image formation was performed. The evaluation conditions and results are summarized in Table 1.

Example 6
“Toner 6” was prepared in the same manner as in Example 1 except that 20 parts by mass of the first binder resin in Example 1 was replaced with silicon dioxide having a particle size of 1.5 μm and 72 parts by mass as coarse particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

Example 7
“Toner 7” was prepared in the same manner as in Example 1 except that 60 parts by mass of the first binder resin in Example 1 was replaced with silicon dioxide having a particle size of 1.5 μm and a mass part of 30 parts as coarse particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

Example 8
“Toner 8” was prepared in the same manner as in Example 7 to form an image. The evaluation conditions and results are summarized in Table 1.

[Comparative Example 1]
"Toner 9" was prepared in the same manner as in Example 1 except that 30 parts by mass of the first binder resin in Example 1 was replaced with polyester resin having a particle size of 3.0 µm and 30 parts by mass as coarse particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

[Comparative Example 2]
“Toner 10” was prepared in the same manner as in Example 1 except that 50 parts by mass of the first binder resin of Example 1 and silicon dioxide having a particle size of 5.2 μm and 10 parts by mass as roughness particles were used. Created and imaged. The evaluation conditions and results are summarized in Table 1.

[Comparative Example 3]
“Toner 11” was prepared in the same manner as in Example 1 except that 30 parts by mass of the first binder resin in Example 1 was replaced with silicon dioxide having a particle size of 0.8 μm and 10 parts by mass as roughness particles. Created and imaged. The evaluation conditions and results are summarized in Table 1.

<Glossiness>
A target image portion was measured at an angle of 60 ° with a gloss meter (Nippon Denshoku Co., Ltd., Handy Gloss Meter PG-1M). The evaluation was performed according to the following criteria, where X is the maximum glossiness and Y is the minimum glossiness.
X / Y is less than 1.20 ... ○
X / Y is 1.20 or more and less than 1.40 ... △
X / Y is 1.4 or more ×

<Fixability>
Five images having the same gloss unevenness evaluation were prepared, passed through the same fixing device as the gloss unevenness, and wound around the fixing roller and paper wrinkles were evaluated according to the following criteria.
・ Separability: 5 sheets cannot be wound
1 or 2 wraps
3 or more wraps around
・ There are no paper wrinkles on all 5 sheets ... ○
1-2 wrinkles occur ... △
Three or more wrinkles occur ×

<Particle state on image>
-Particle separation An image similar to the image of uneven glossiness was prepared, and a cloth having a size of 1 cm x 1 cm was placed on the image and rubbed at 1 kg / cm ² and 1 cm / sec. Thereafter, images with a range of 100 μm ² were observed at three randomly selected portions of the friction portion with an electron microscope.
No leaving mark ... ○
Detachment marks less than 300 / mm ² ... △
Detachment mark is 300 pieces / mm ² or more ... ×
-Particle embedding One image similar to the image of uneven glossiness was prepared, and an image of 1 mm × 1 mm in the center portion in the paper passing direction was observed with an electron microscope.
Roughness particles can be confirmed over the entire surface ...
A portion where roughness particles are not observed exists in a range of less than 20%.
There are 20% or more parts where roughness particles are not seen ... ×

27 fixing device 61 fixing roller 61a crown portion 61b reverse crown portion 61c linear portion 62 pressure roller 62a crown portion 62b reverse crown portion 62c linear portion 63 heating source 65 pressure belt 66 pressing member 66a convex surface portion 66b concave surface portion 660 pressing surface 611 Core material 612 Elastic layer 621 Core material 622 Elastic layer H Height difference N Fixing nip P Recording paper Q Top portion U Bottom portion W Maximum passage width of recording medium

JP 2004-109697 A

Claims (19)

In an image forming method including a step of fixing an unfixed toner image formed using toner on a support using a contact heating type fixing device,
The fixing device includes a fixing roller heated by a heating source, and a pressure roller disposed in pressure contact with the fixing roller, and a fixing nip formed by pressure-contacting the fixing roller and the pressure roller. The unfixed toner image on the recording medium is fixed to the recording medium by passing the recording medium through
The fixing roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and each reverse crown portion whose outer peripheral surface is formed in a reverse crown shape,
The pressure roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and one reverse crown portion whose outer peripheral surface is formed in a reverse crown shape, and
The crown portion of the fixing roller and the reverse crown portion of the pressure roller are made to correspond to each other, and the reverse crown portion of the fixing roller and the crown portion of the pressure roller are made to correspond to each other. A fixing device in which the pressure rollers are pressed against each other,
The toner contains at least a colorant, a resin, and roughness particles, and the roughness particles have a volume average particle size of 1.0 to 5.0 μm, 200 ° C., 0.03 N / mm ² , 1 The shape change rate (X) represented by the following formula (1) in minutes is a filler of 10% or less,
An image forming method.
X (%) = {(A−B) / A} × 100 (1)
However, the circularity before pressure treatment is A, and the circularity B after pressure treatment is B.   In the fixing device, when the fixing roller and the pressure roller are disposed in a state where the crown portion and the reverse crown portion are in contact with each other in a no-load state, The image forming method according to claim 1, wherein a gap is not formed between the reverse crown portion.   The image forming method according to claim 1, wherein the fixing device continuously forms the crown portion and the reverse crown portion of each of the fixing roller and the pressure roller in an axial direction.   The fixing roller and the pressure roller have an elastic layer, and the fixing roller and the pressure roller are disposed in a state where the crown portion and the reverse crown portion are in contact with each other in an unloaded state. The image forming method according to claim 1, wherein a sum of thicknesses of the elastic layers of the fixing roller and the pressure roller in an arbitrary cross section in the axial direction is set to be constant.   5. The image formation according to claim 1, wherein the crown portion and the reverse crown portion are disposed over a portion of the fixing roller and the pressure roller corresponding to at least the entire maximum width of the recording medium. Method.   The image forming method according to claim 1, wherein the crown portion and the reverse crown portion are disposed in a portion corresponding to a part of a maximum passage width of the recording medium of the fixing roller and the pressure roller. .   The linear part is formed in at least one of the crown part and the reverse crown part of the fixing roller and at least one of the crown part and the reverse crown part of the pressure roller. Image forming method.   In a load state in which the fixing roller and the pressure roller are pressed against each other, a height difference between the top of the crown portion and the bottom of the reverse crown portion in the fixing nip is 0.16 mm or more and 0.8 mm or less. The image forming method according to claim 1, which is set to 1.   The fixing roller and the pressure roller are configured by covering an outer peripheral surface of a core material with an elastic layer, and the thickness of at least one of the core material and the elastic layer varies in the axial direction. The image forming method according to claim 1, wherein the crown portion and the reverse crown portion are formed.   The fixing roller is constituted by a roller having no elastic layer on the outer peripheral surface of the core material, and the outer peripheral surface of the core material of the fixing roller is curved in the axial direction, whereby the crown portion and the reverse crown are formed. The image forming method according to claim 1, wherein a portion is formed.   The pressure roller is configured by coating an outer peripheral surface of a core material with an elastic layer, and the crown is formed by curving the outer peripheral surface of the core material of the pressure roller in the axial direction. The image forming method according to claim 10, wherein a portion and the reverse crown portion are formed.   The ends of the fixing roller and the pressure roller in the same axial direction are positioned in the axial direction, and the ends of the fixing roller and the pressure roller opposite to the positioned ends. The image forming method according to claim 1, wherein the portion is configured to be axially displaceable. In an image forming method comprising a step of fixing a toner image formed using a toner containing at least a resin and a colorant on a support using a contact heating type fixing device,
The fixing device includes a fixing roller heated by a heating source, an endless pressure belt, and a pressing member that presses an inner peripheral surface of the pressure belt and presses the pressure belt against the fixing roller. And fixing the unfixed image on the recording medium to the recording medium by passing the recording medium through a fixing nip formed by press-contacting the fixing roller and the pressure belt.
The fixing roller has at least one crown portion whose outer peripheral surface is formed in a crown shape and each reverse crown portion whose outer peripheral surface is formed in a reverse crown shape,
The pressing surface of the pressing member that presses the pressure belt has at least one each of a convex surface portion formed in a convex shape and a concave surface portion formed in a concave shape,
The crown portion of the fixing roller and the concave surface portion of the pressing member are arranged in correspondence with each other, the reverse crown portion of the fixing roller and the convex surface portion of the pressing member are arranged in correspondence with each other, and A fixing device, wherein the pressing belt is pressed by a pressing member, and the fixing roller and the pressing belt are pressed against each other;
The toner contains at least a colorant, a resin, and roughness particles, and the roughness particles have a volume average particle size of 1.0 to 5.0 μm, 200 ° C., 0.03 N / mm ² , 1 The shape change rate (X) represented by the following formula (1) in minutes is a filler of 10% or less,
An image forming method.
X (%) = {(A−B) / A} × 100 (1)
However, the circularity before pressure treatment is A, and the circularity B after pressure treatment is B.   The image forming method according to claim 1, wherein the material of the roughness particles is one or more fillers selected from resins, metals, and inorganic oxides.   The image forming method according to claim 1, wherein the roughness particles are colorless or have a similar color to the colorant.   The image forming method according to any one of claims 1 to 15, wherein a ratio of roughness particles contained in the toner is 1.0 to 70 parts by mass with respect to 100 parts by mass of the colored resin particles.   The image forming method according to claim 1, wherein a softening point of the toner is 110 ° C. to 140 ° C.   A process cartridge having at least an image carrier, a developing unit, and a fixing unit, and detachable from an image forming apparatus, wherein the toner according to claim 1 is stored in the developing unit. A process cartridge using the fixing device according to claim 1 as a fixing means.   An image forming apparatus comprising the process cartridge according to claim 18.

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