JP2007193099A - Image forming apparatus, image forming method and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of achieving energy saving and low-temperature fixing, excellent in hot offset resistance and capable of providing a high-quality image. <P>SOLUTION: The image forming apparatus 100 comprises: at least image carriers 40 which bear latent images; developing means 4 to develop the latent images with toners; transfer means 62, 22 to transfer toner images on surfaces of the image carriers 40; and a fixing means 25 to fix the toner images by applying heat and pressure, wherein the toners each contain a binder resin containing at least a crystalline polyester resin and an amorphous resin and a colorant, and the fixing means 25 has an electromagnetic wave generating means 254 and an electromagnetic induction heating element 253 which generates heat when a magnetic field generated from the electromagnetic wave generating means 254 is applied, the electromagnetic induction heating element 253 containing a magnetic compensating alloy in a surface or interior portion thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer. More specifically, the present invention relates to an image forming apparatus that fixes a toner image using an electromagnetic induction heating method.

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method such as a copying machine or a printer, a toner image formed on a photoconductor as an image carrier is transferred to a transfer target (hereinafter sometimes referred to as a recording material). Then, a fixing device for fixing an unfixed toner image on a recording material by heat and pressure is used.
For this type of fixing device, a heat-heat roller type fixing device is widely used because of its energy efficiency. In this type of fixing device, a heater such as a halogen lamp is used as a heat source in a fixing roller (heat roller), and a nip portion is formed by the fixing roller and a pressure roller made of a heat-resistant elastic member. A method of fixing an unfixed toner image by heat and pressure by introducing and conveying a recording material is common.

In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimiles. In order to achieve these required performances, it is important to improve the thermal efficiency of the fixing device used in the image forming apparatus.
Although the heating roller type fixing device is somewhat excellent in terms of energy efficiency, since the fixing roller is heated using radiant heat from a halogen lamp, the temperature of the fixing roller is fixed after the power is turned on. It takes a relatively long time to reach a suitable predetermined temperature (hereinafter referred to as warm-up time). Meanwhile, there is a problem that the user cannot use the copying machine and is forced to wait for a long time.
On the other hand, if a large amount of power is applied to the fixing roller in order to shorten the warm-up time and improve the operability for the user, there is a problem that the power consumption in the fixing device increases and this is contrary to energy saving. .
For this reason, in order to increase the value of products such as copying machines, it is necessary to achieve both energy savings by reducing power consumption, shortening warm-up time, and improving user operability by quick printing in fixing devices. , Has attracted more and more attention.

In recent years, as an apparatus that meets such a demand, as shown in Patent Document 1 or Patent Document 2, an induction heating type fixing apparatus using high-frequency induction as a heating source has been proposed. In this induction heating fixing device, a coil is concentrically disposed inside a hollow fixing roller made of a metal conductor, and an induction eddy current is generated in the fixing roller by a high frequency magnetic field generated by flowing a high frequency current through the coil. Due to the skin resistance of the fixing roller itself, the fixing roller itself as an electromagnetic induction heating element causes Joule heat generation.
According to this induction heating type fixing device, since the electric-heat conversion efficiency is greatly improved, the warm-up time can be shortened. In addition, an electromagnetic induction heating element as a heat generation source can be arranged in the vicinity of the toner image, and only the fixing roller can generate heat. Compared to the fixing device, the warm-up time can be shortened.

The fixing device adopting the above-described electromagnetic induction heating method is formed after a rotating member (such as a fixing roller) or a traveling member (such as an endless belt) serving as an electromagnetic induction heating element is heated by a magnetic field generating unit. In this configuration, the toner image on the recording material as a transfer medium is fixed by moving or rotating to the nip portion.
In the above-described induction heating type fixing device, in order to take advantage of the feature that the warm-up time can be shortened, it is preferable to reduce the heat capacity of the electromagnetic induction heating element such as the fixing roller or the endless belt as much as possible. For this reason, attempts have been made to further reduce energy consumption and speed by reducing the thickness of the electromagnetic induction heating elements such as the fixing roller and the fixing belt as much as possible.

However, when an attempt is made to reduce the heat capacity of the heating element by the above method, for example, if the thickness of the fixing roller is made too thin, the pressing force at the fixing nip is set high due to the rigidity of the fixing member. And it becomes difficult to set the fixing temperature low.
Furthermore, it becomes difficult to transfer heat in the direction of the rotation axis of the fixing roller. For example, when a small size paper (transfer object) is continuously passed, fixing is performed between the paper passing portion and the non-paper passing portion. Roller temperature difference tends to increase. At this time, if the temperature of the fixing roller is adjusted with reference to the sheet passing portion, the temperature suitable for fixing in the non-sheet passing portion greatly exceeds, and toner offset occurs on the surface of the fixing roller in the non-sheet passing portion. Or when the paper is wound around the fixing roller, a paper jam occurs.
Such a phenomenon also occurs when, for example, an endless fixing belt is used as an induction heating element. For this reason, in order to shorten the warm-up time while saving energy, it is important to use a toner having excellent low-temperature fixability in addition to the improvement of the fixing device.

As means for adjusting the thermal characteristics of the toner, generally, means such as lowering the glass transition temperature (Tg) of the resin used in the toner or lowering the softening temperature by lowering the molecular weight of the resin are taken. . However, the thermal characteristics of amorphous resins contained in commonly used toners are those in which the melt viscosity gradually decreases from Tg. Therefore, the melt viscosity is such that the resin exhibits a fixing function and the Tg of the resin. There is usually a difference of several tens of degrees Celsius from the temperature at which the temperature decreases (for example, 1/2 outflow temperature [T (F1 / 2)]).
For this reason, if the glass transition temperature (Tg) of the resin is lowered too much by fixing the toner at a low temperature, the heat-resistant storage stability as the toner is deteriorated, or the molecular weight is decreased to reduce the resin 1/2 outflow temperature [T If (F1 / 2)] is lowered too much, problems such as lowering the hot offset occurrence temperature occur.

In order to solve such a problem, an attempt to add a specific non-olefinic crystalline polymer having sharp melt property at the glass transition temperature in the binder resin (see Patent Document 3), or crystalline polyester Attempts have been made (see Patent Documents 4 to 8).
The polyester resin having crystallinity undergoes a crystal transition at the glass transition temperature (Tg), and at the same time, the melt viscosity suddenly decreases from the solid state and exhibits a fixing function to a recording medium such as paper. Therefore, by combining a crystalline polyester resin and an amorphous resin, the melt viscosity of the entire binder resin is reduced without deteriorating the heat resistant storage stability and hot offset resistance, and the toner can be fixed at a low temperature. Can be achieved. This cannot be realized with toner using only amorphous resin.

However, when the toner containing the crystalline polyester is used, the following problems occur.
In other words, the induction heating type fixing device can raise the temperature of the surface of the fixing member to a high temperature region in a short time as compared with the case of fixing by the heat roller method, but in order to take advantage of this advantage, the heat capacity of the heating element is increased. If it is made smaller, the surface temperature of the fixing member tends to overshoot. In this case, as described above, when a toner containing a crystalline polyester having a low melting point and a low melt viscosity is used, the toner tends to be hot offset on the surface of the fixing member.
For example, when a cleaning member is placed in contact with the surface of the fixing member in order to collect the toner attached to the surface of the fixing member, there arises a problem that the toner adheres and accumulates on the cleaning member.

JP 59-33787 Japanese Patent Publication No. 5-9027 JP 62-63940 A JP 2003-167384 A Japanese Patent No. 2931899 JP 2001-222138 A JP 2004-221740 A JP 2004-279476 A

  Therefore, in view of the above problems, the present invention is capable of energy saving and low-temperature fixing, and has an image forming apparatus and an image forming method that are excellent in hot offset resistance and can provide a high-quality image, and the image. It is an object of the present invention to provide a process cartridge provided in a forming apparatus.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. At least an image carrier for carrying a latent image; and developing means for developing the latent image with toner;
An image forming apparatus comprising: a transfer unit that transfers a toner image on the surface of an image carrier; and a fixing unit that fixes the toner image by heating and pressurizing. The toner includes at least a crystalline polyester resin and a non-crystalline polyester resin. A toner containing a binder resin containing a crystalline resin and a colorant, wherein the fixing means is an electromagnetic wave generating means, and an electromagnetic induction heating element that generates heat when a magnetic field generated by the electromagnetic wave generating means is applied. And the electromagnetic induction heating element contains a magnetic shunt alloy on the surface or inside thereof.
2. The image forming apparatus according to the present invention includes: In the invention described in (1), the fixing unit includes at least two rotating members and an endless traveling moving member that is wound around and moves between the rotating members, and the electromagnetic induction heating element includes: It is preferable that it is the said travel movement member or the said rotation member.
3. The image forming apparatus according to the present invention includes: Or 2. In the invention described in item 1, it is preferable to have a cleaning member that contacts the traveling member.
4). The image forming apparatus according to the present invention includes: Or 3. In the invention according to any one of the above, the electromagnetic induction heating element is a traveling movement member, the traveling movement member is formed of a support layer and a release layer, and the support layer is made of the magnetic shunt alloy. It is preferable to contain.
5). The image forming apparatus according to the present invention includes: Or 4. In the invention according to any one of the above, it is preferable that the traveling member is used at a surface temperature of 200 ° C. or less.
6). The image forming apparatus according to the present invention includes: Or 5. In the invention described in any one of the above, the crystalline polyester resin preferably has a melting point of 69 to 137 ° C.
7). The image forming apparatus according to the present invention includes: Or 6. In any one of the inventions, the content of the crystalline polyester resin in the binder resin is preferably 2.5 to 50 parts by weight with respect to 100 parts by weight of the total binder resin.
8). The image forming apparatus according to the present invention includes: Or 7. In the invention according to any one of the above, the crystalline polyester has a softening temperature [T (F1 / 2)] of 80 to 140 ° C., and the toner has a softening temperature [T (F1 / 2) of the crystalline polyester. )], It is preferable to contain at least one wax having a low melting point.
9. The image forming apparatus according to the present invention includes: Or 8. In the invention according to any one of the above, the toner preferably has a Tg in the range of 35 to 70 ° C.
10. The image forming apparatus according to the present invention includes: Or 9. In any of the inventions, the toner preferably contains a magnetic substance.
11. The image forming apparatus according to the present invention includes: Or 9. In the invention according to any one of the above, it is preferable that the toner is used by being mixed with a magnetic carrier coated with a resin.
12 The image forming apparatus according to the present invention includes: To 11. In any one of the inventions, it is preferable that the magnetic shunt alloy is an iron-nickel alloy.

13. The image forming apparatus according to the present invention includes: Or 12. In the invention described in any one of the above, it is preferable that at least the image carrier and the developing unit are integrally supported, and a process cartridge that is detachably formed in the image forming apparatus is provided.

14 The image forming method of the present invention includes a step of forming an electrostatic latent image on an image carrier, a step of developing the electrostatic latent image with a developer containing toner, and forming a toner image. An image forming method comprising: a step of transferring onto a transfer member; and a fixing step of fixing the toner image on the transfer member onto a recording medium by heating and pressing with a fixing member, and used in the developing step The toner for developing an electrostatic charge image is a toner containing at least a binder resin containing a crystalline polyester resin and an amorphous resin, and a colorant. In the fixing step, an electromagnetic wave generating means, and the electromagnetic wave generation A fixing device having an electromagnetic induction heating element that generates heat when a magnetic field generated by the means is applied is used, and the electromagnetic induction heating element preferably contains a magnetic shunt alloy on the surface or inside thereof.
15. The image forming method includes: Thru 13. It is preferable to be applied to the image forming apparatus described in any of the above.

  According to the present invention, energy saving and low-temperature fixing can be improved, and further, high-quality images can be stably provided with excellent hot offset resistance.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention. In the figure, reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which the copying apparatus is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) mounted thereon.
The copying apparatus main body 100 has a tandem type in which four image forming units 18 each having various units for performing an electrophotographic process such as charging, developing, and cleaning are arranged in parallel around a photosensitive member 40 as a latent image carrier. An image forming apparatus 20 is provided. Above the tandem type image forming apparatus 20, there is provided an exposure apparatus 21 that exposes the photoreceptor 40 with laser light based on image information to form a latent image. Further, an intermediate transfer belt 10 made of an endless belt member is provided at a position facing each photoreceptor 40 of the tandem type image forming apparatus 20. A primary transfer unit 62 for transferring the toner images of the respective colors formed on the photoconductor 40 to the intermediate transfer belt 10 is disposed at a position facing the photoconductor 40 via the intermediate transfer belt 10.
A secondary transfer device 22 that collectively transfers the toner images superimposed on the intermediate transfer belt 10 onto transfer paper conveyed from the paper feed table 200 is disposed below the intermediate transfer belt 10. The secondary transfer device 22 is configured by spanning a secondary transfer belt 24 that is an endless belt between two rollers 23, and is disposed by pressing against the support roller 16 via the intermediate transfer belt 10. The toner image on 10 is transferred onto a transfer sheet. A fixing device 25 for fixing the image on the transfer paper is provided beside the secondary transfer device 22. The configuration of the fixing device 25 will be described in detail later.
The secondary transfer device 22 described above also has a sheet transport function for transporting the transfer paper after image transfer to the fixing device 25. Of course, a transfer roller or a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to provide this sheet conveyance function together.
In the illustrated example, a reversing device 28 for reversing the transfer paper so as to record images on both sides of the transfer paper is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. .

For the developing device 4 of the image forming unit 18, a developer containing toner, which will be described in detail later, is used. In the developing device 4, the developer carrying member carries and conveys the developer, and develops the latent image on the photoconductor 40 at a position facing the photoconductor 40.
Note that an alternating electric field can be applied when developing the latent image on the photoconductor 40. By applying the alternating electric field, the developer is activated, the charge amount distribution of the toner can be narrowed, and the developability can be improved.

  Further, the developing device 4 can be a process cartridge that is integrally supported together with the photoreceptor 40 and is detachably formed on the main body of the image forming apparatus. In addition, the process cartridge may include a charging unit and a cleaning unit.

The operation of the image forming apparatus is as follows.
First, a document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed. Hold it down.
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At that time, the scanner 300 is immediately driven, and the first traveling body 33 and the second traveling body 34 travel. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is rotationally driven by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer belt 10 is rotated and conveyed. To do. At the same time, the individual image forming means 18 rotates the photoconductors 40 to form black, yellow, magenta, and cyan monochrome images on the photoconductors 40, respectively. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and is transferred by the secondary transfer device 22. A color image is recorded on the sheet.

The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image, and then the switching roller 55 is used to switch the discharge image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer belt cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after image transfer, and is prepared for re-image formation by the tandem image forming apparatus 20.

The fixing device 25 will be described in detail. FIG. 2 is an overall configuration diagram of the fixing device 25 according to the present invention.
As shown in FIG. 2, the fixing device 25 includes a fixing roller 251, a counter roller (heating roller) 252 that is arranged in parallel with the fixing roller 251, and is formed between a fixing roller 251 and the counter roller 252. A fixing belt 253 as an endless traveling member having a magnetic material wound inside, an induction coil 254 as electromagnetic wave generating means disposed on the side of the opposing roller 252, and a fixing belt 253. A pressure roller 256 that presses the fixing roller 251 and forms a nip portion 255 on the fixing belt 253.
The induction coil 254 as the electromagnetic wave generating means serves to electromagnetically heat the fixing belt 253 used as an electromagnetic induction heating element in this embodiment.

The fixing roller 251 has a heat insulating layer on the outer side of a metal core such as aluminum or iron, and has an outer diameter set to 40 mm. Since the heat insulation layer needs to have heat resistance, silicone rubber (including sponge) or the like is used. In this embodiment, silicone rubber is used. The lower the thermal conductivity of the material used for the heat insulating layer, the more effective it is, and it is generally preferable to be 0.2 W / m / K or less.
In this embodiment, it is 0.2 W / m / K. The counter roller 252 is formed of aluminum, SUS, or the like whose core metal is a nonmagnetic material. In this embodiment, SUS is used.

  In the pressure roller 256, a heat-resistant elastic layer such as silicone rubber is formed on the outer periphery of the core metal, and a surface release layer made of a fluororesin is formed on the outer periphery of the heat-resistant elastic layer. Further, in order to improve the separation property of the transfer medium P from the fixing belt 253, the surface hardness of the pressure roller 256 is formed to be higher than the surface hardness of the fixing roller 251. Therefore, when the fixing roller 251 is pressed by the pressure roller 256 via the fixing belt 253, a part of the fixing belt 253 is deformed in a convex shape toward the fixing roller 251, and a nip portion 255 is formed in the fixing belt 253. . The thickness of the heat resistant elastic layer of the pressure roller 256 is about 1 mm to several mm. In the present embodiment, a pressure roller having a heat-resistant elastic layer having a thickness of 1.2 mm is used.

The induction coil 254 is wound around an excitation core 257 having a substantially concave cross section made of ferrite or permalloy. When a high frequency current of several kHz to several hundred kHz is passed through the induction coil 254, an induction current is generated in the fixing belt 253. Due to this induction current, the fixing belt 253 generates heat locally in the vicinity of the induction coil 254, and the temperature rises rapidly.
Further, a temperature sensor 258 for detecting the temperature of the fixing belt 253 heated by electromagnetic induction and a control device 259 for taking in a detection signal from the temperature sensor 258 and controlling a high-frequency current flowing through the induction coil 254 are provided. Yes.

  Further, below the counter roller 252, there is provided a guide plate 260 that conveys a transfer target (hereinafter sometimes referred to as recording paper) P to the fixing device 25. Unfixed toner T adheres to the surface of the transfer target P.

  The fixing belt 253 is provided with a belt cleaning roller 261 in contact with the outer peripheral surface. In this embodiment, the belt cleaning roller 261 is a SUS roller having a diameter of 10 mm.

FIG. 3 is a longitudinal sectional view of the fixing belt 253 used in the fixing device according to the present invention. As shown in FIG. 3, the fixing belt 253 has a laminated structure in which a base material 253a, an elastic layer 253b, and a release layer 253c are laminated in order from the lower side.
The base material 253a is formed of an endless belt, and a magnetic shunt alloy powder is blended in the resin based on a heat resistant resin. As the material of the heat-resistant resin as a base, polyimide, polyamideimide, polyetherketone (PEEK), or the like can be used. In addition, the thickness of the base material 253a is desirably 20 μm to 100 μm from the rigidity and heat capacity of the belt. In this embodiment, polyimide having a thickness of 40 μm is used.
The elastic layer 253b is provided in order to obtain image uniformity, and a heat-resistant rubber such as a silicone rubber having a thickness of about 100 to 300 μm or a fluorine rubber is used. In this embodiment, a silicone rubber having a thickness of 200 μm is used.
The release layer 253c is provided to make pressure contact with the recording paper P and the toner T. For this reason, as the release layer 253c, it is preferable to use a fluororesin because it is excellent in heat resistance and durability.

In this embodiment, as described above, the base material 253a is formed of a material in which a magnetic shunt alloy is dispersed. Here, the Curie temperature of the magnetic shunt alloy is set to be lower than the hot offset temperature of the toner used. For example, when the hot offset temperature in the fixing device 25 is 205 ° C., the powder of the iron-nickel alloy is dispersed in the resin of the base material 253a so that the Curie temperature of the magnetic shunt alloy is 200 ° C. .
As the magnetic shunt alloy, iron-nickel-chromium, iron-nickel-cobalt or the like can be used in addition to the iron-nickel alloy.

  When the fixing device 25 shown in FIG. 2 includes the fixing belt 253 shown in FIG. 3, when a high frequency current is passed through the induction coil 254, the base material 253a of the fixing belt 253 is heated by electromagnetic induction, and the fixing belt 253 generates heat. To do. The unfixed toner on the transfer medium P can be fixed by passing the transfer medium P conveyed on the guide plate 261 between the fixing roller 251 and the pressure roller 256.

In the nip portion 255, the unfixed toner that has not been fixed on the transfer target P slightly moves on the fixing belt 253, but this small amount of unfixed toner is provided in pressure contact with the fixing belt 253. Collected by the belt cleaning roller 261.
If unfixed toner remains on the fixing belt 253, the toner is transferred onto the transfer medium P to be transported next, and causes stains on the image.

  In the case of the fixing device using the electromagnetic induction heating method as described above, instantaneous heating can be performed, while the temperature of the heating element surface temporarily becomes high when the temperature is raised. There is a problem that the shooting phenomenon is likely to occur. In particular, this phenomenon becomes significant when the thickness of the heating element that generates heat by electromagnetic induction is made as thin as possible and the heat capacity is reduced.

However, in the fixing device 25 according to the present invention, the fixing belt 253 can be instantaneously heated by electromagnetic induction heating means, and the magnetic shunt alloy is dispersed on the base material 253a of the fixing belt 253 as an electromagnetic induction heating element. Therefore, the surface of the fixing belt 253 can be used while suppressing the phenomenon of overshoot that causes the temperature of the fixing belt 253 to be abnormally high.
Specifically, the temperature of the surface of the fixing belt 253 can be used at 200 ° C. or lower by adjusting the nickel content in the magnetic shunt alloy.

When the temperature of the surface of the fixing belt 253 becomes abnormally high, the toner carried on the transfer material P is heated excessively in the fixing nip portion 255 and melts excessively, and the releasability from the fixing belt 253 decreases. As a result, a so-called hot offset phenomenon that the toner adheres on the fixing belt 253 easily occurs, and the amount of toner adhering on the fixing roller 253 increases slightly.
In particular, when a resin having a low melting point and a low melt viscosity, as described in detail below, is blended in the toner, an excellent effect on low-temperature fixability as a toner can be obtained, but the surface of the fixing belt 253 When the temperature of the toner reaches a certain temperature or more, the possibility that the above-described phenomenon occurs increases, and the amount of toner collected from the fixing belt 253 onto the belt cleaning roller 261 increases, so that the amount of toner collected on the belt cleaning roller 261 increases. The phenomenon that toner adheres and accumulates becomes remarkable. When the amount of the collected toner attached on the belt cleaning roller 261 increases, the toner is remelted by heat received from the surface of the fixing belt 253 and melted onto the fixing belt 253. As described above, the toner melted on the fixing belt 253 again causes the transfer body P to be supplied to the fixing device 25 to be wound around the fixing belt 253, or the toner is transferred onto the transfer body P. This may cause image smearing due to the transfer.

  However, in the fixing device 25 of the present invention, as described above, since the surface of the fixing belt 253 is adjusted so that it can be used at a certain temperature or lower, it contains a resin having a relatively low melting point and has low temperature fixing properties. Even when excellent toner is used, the occurrence of hot offset on the fixing belt 253 can be avoided, and the amount of toner adhering on the belt cleaning roller 261 can be prevented from increasing significantly.

In the fixing device 25 of the present invention, the induction heating element that generates heat by the induction coil 254 can be the opposing roller 252.
FIG. 4 is a cross-sectional view illustrating the configuration of the upper half of the fixing roller 252 wound around the counter roller 252 and the counter roller 252 of the fixing device according to the second embodiment, which is used in the image forming apparatus of the present invention. .

The fixing belt 253 has a laminated structure in which a base material 253a, an elastic layer 253b, and a release layer 253c are laminated in order from the lower side.
The base material 253a is formed of an endless belt made of a heat resistant resin (nonmagnetic material). As a material of the heat resistant resin, polyimide, polyamideimide, polyetherketone (PEEK) or the like can be used. From the viewpoint of the rigidity and heat capacity of the belt, the thickness of the substrate 253a is desirably 20 μm to 100 μm. Unlike the first embodiment, the base material 253a used for the fixing belt 253 according to the present embodiment is configured without containing a magnetic shunt alloy.
The configurations of the elastic layer 253b and the release layer 253c are the same as those described in the first embodiment.

  In this embodiment, the opposing roller 252 has a cored bar 252a made of nonmagnetic aluminum or the like, and a magnetic shunt alloy layer 252b is provided on the outer peripheral surface of the cored bar 252a. Examples of the magnetic shunt alloy material included in the magnetic shunt alloy layer 252b include iron-nickel alloy, iron-nickel-chromium, iron-nickel-cobalt, and the like. Further, the amount of nickel of the magnetic shunt alloy contained in the magnetic shunt alloy layer 252b is adjusted so that its Curie temperature becomes 200 ° C.

  When the fixing device 25 shown in FIG. 2 includes the opposing roller 252 and the fixing belt 253 configured as shown in FIG. 4, when a high frequency current is passed through the induction coil 254, the magnetic shunt alloy contained in the magnetic shunt alloy layer 252b. Is heated by electromagnetic induction, and the opposing roller 252 generates heat, and the heat generation heats the fixing belt 253. The unfixed toner on the transfer medium P can be fixed by passing the transfer medium P conveyed on the guide plate 261 between the fixing roller 251 and the pressure roller 256.

  In this embodiment, since the counter roller 252 can be used in a temperature range of 200 ° C. or less, the temperature of the surface of the fixing belt 253 heated by the counter roller 252 does not increase to 200 degrees or more, and the fixing is performed. Occurrence of hot offset on the surface of the belt 253 is prevented, and it is possible to prevent the toner adhesion amount on the belt cleaning roller 261 from increasing significantly.

  Also, in the present embodiment, unlike the first embodiment, since the magnetic shunt alloy is not included in the members constituting the fixing belt 253, the flexibility of the fixing belt 253 is improved and the fixing belt 253 is cracked. As a result, the life of the fixing belt 253 can be improved.

In the fixing device of the present invention, the fixing roller 251 in FIG. 2 may be an induction heating element, and the surface layer of the fixing roller 251 may contain a magnetic shunt alloy.
In this case, a magnetic shunt alloy layer is provided between the outer peripheral surface of the heat insulating layer provided on the fixing roller or between the metal core and the heat insulating layer, and, for example, from the induction coil 254 and the excitation core 257 shown in FIG. The electromagnetic wave generating means may be installed inside or outside the fixing roller 251 and the fixing roller 251 may generate heat by the electromagnetic wave generating means.
The fixing device 25 according to the present invention is not limited to the belt fixing device as described above, and can be applied to other fixing devices such as a heat roller system. In the case of a heat roller type fixing device, one of rotating members such as a fixing roller or a pressure roller contains a magnetic shunt alloy, and the magnetic shunt alloy contained in this rotating member is It suffices if it is configured to generate heat.

Next, the electrostatic image developing toner used in the developing device 4 will be described in detail.
The toner for electrophotography of the present invention contains a binder resin composed mainly of a crystalline polyester resin A having crystallinity and an amorphous amorphous resin B.
The crystalline polyester resin A undergoes a crystal transition in the vicinity of the glass transition temperature (Tg), and at the same time, the melt viscosity rapidly decreases from the solid state and reaches a viscosity that exhibits a fixing function to a recording medium such as paper. For this reason, by including it in the binder resin together with the amorphous resin B, it is possible to obtain a toner having good low-temperature fixability and good blocking resistance and hot offset resistance.
As content of crystalline polyester resin A with respect to binder resin whole quantity, it is preferable that it is 2.5-50 weight part with respect to 100 weight part of binder resin, More preferably, it is 40 weight% or less. When the content of the polyester resin A with respect to the total amount of the binder resin exceeds 50 parts by weight, although the effect for fixing at low temperature is greatly obtained, the hot offset resistance as a resin is deteriorated.
On the other hand, if it is less than 2.5 parts by weight, the effect on the low-temperature fixability cannot be sufficiently obtained. When the content of the crystalline polyester A in the binder resin is within the above range, it penetrates into the paper fibers as the transfer target and melts and spreads sufficiently on the paper, and has a high image density. At the same time, a toner having excellent heat-resistant storage stability can be obtained.

(Crystalline polyester resin A)
The crystalline polyester resin A undergoes a crystal transition in the vicinity of the glass transition temperature (Tg), and at the same time, the melt viscosity rapidly decreases from the solid state and reaches a viscosity that exhibits a fixing function to a recording medium such as paper.
Normally, the amorphous resin used for the binder resin gradually decreases in melt viscosity from Tg, so that the Tg of the toner and the temperature at which the toner can be fixed on the fixing medium (for example, 1/2 outflow temperature [ T (F1 / 2)], hereinafter referred to as the softening temperature), there is a large gap, and in order to improve the low-temperature fixability of the toner, the glass transition temperature of the resin contained in the binder resin It was necessary to lower the softening point of the resin by lowering the molecular weight or lowering the molecular weight. However, when the thermal characteristics of the resin are adjusted in this way, there arises a problem that the heat resistant storage stability and hot offset resistance of the toner are insufficient.

  The crystalline polyester resin (A) having crystallinity used in the binder resin in the present invention is a crystalline aliphatic polyester containing an ester bond represented by the following general formula (I) in its molecular main chain. It consists of resin.

  In the formula (I), R represents a linear unsaturated aliphatic divalent carboxylic acid residue, and is a linear unsaturated aliphatic group having 2 to 20 carbon atoms, preferably 2 to 4 carbon atoms. n is an integer of 2 to 20, preferably 2 to 6.

The presence of the structure of the general formula (I) can be confirmed by solid C ¹³ -NMR.
Specific examples of the linear unsaturated aliphatic group include linear unsaturated divalent carboxylic acids such as maleic acid, fumaric acid, 1,3-n-propene dicarboxylic acid, and 1,4-n-butene dicarboxylic acid. Mention may be made of linear unsaturated aliphatic groups derived from acids.

In the general formula (I), (CH ₂ ) n represents a linear aliphatic dihydric alcohol residue. Specific examples of the linear aliphatic divalent (or trivalent or higher) alcohol residue in this case include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and the like. And those derived from linear aliphatic dihydric alcohols.
The crystalline polyester resin (A) uses a linear unsaturated aliphatic dicarboxylic acid as its acid component, so that it can form a crystal structure more easily than when an aromatic dicarboxylic acid is used.

In this case, a small amount of other polyvalent carboxylic acid can be added to the polyvalent carboxylic acid component as necessary. In this case, the polyvalent carboxylic acid includes (i) an unsaturated aliphatic divalent carboxylic acid having a branched chain, (ii) a saturated aliphatic divalent carboxylic acid, and a saturated aliphatic trivalent carboxylic acid. In addition to polyvalent carboxylic acids, (iii) aromatic polyvalent carboxylic acids such as aromatic divalent carboxylic acids and aromatic trivalent carboxylic acids are included.
The addition amount of these polyvalent carboxylic acids is usually 30 mol% or less, preferably 10 mol% or less, based on the total carboxylic acid, and is appropriately added within the range where the resulting polyester has crystallinity.

  Specific examples of polyvalent carboxylic acids that can be added as needed include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, citraconic acid, phthalic acid, isophthalic acid, terephthalic acid, etc. A divalent carboxylic acid of: trimetic anhydride, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, And trivalent or higher polyvalent carboxylic acids such as 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxypropane, 1,2,7,8-octanetetracarboxylic acid, etc. it can.

A trivalent or higher polyhydric alcohol can be added to the polyhydric alcohol component, if necessary, in addition to a small amount of an aliphatic branched dihydric alcohol or cyclic dihydric alcohol. The addition amount is 30 mol% or less, preferably 10 mol% or less, based on the total alcohol, and is appropriately added within the range in which the resulting polyester has crystallinity.
Examples of polyhydric alcohol added as needed include 1,4-bis (hydroxymethyl) cyclohexane, polyethylene glycol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, glycerin and the like.

The crystalline polyester resin A is a polyvalent carboxylic acid comprising (1) a linear unsaturated aliphatic divalent carboxylic acid or a reactive derivative thereof (an acid anhydride, a lower alkyl ester having 1 to 4 carbon atoms, an acid halide, etc.). It can be produced by polycondensation reaction of an acid component and (2) a polyhydric alcohol component comprising a linear aliphatic diol by a conventional method.
The polyester in the present invention can be obtained by performing a dehydration condensation reaction or a transesterification reaction using the above raw material components in the presence of a catalyst. The reaction temperature and reaction time at this time are not particularly limited, but are usually 20 to 300 ° C. and 30 minutes to 24 hours.

In the present invention, whether or not the resin used for the binder resin has crystallinity can be confirmed by whether or not a peak exists in the X-ray diffraction pattern by the powder X-ray diffractometer.
The polyester resin A having crystallinity used in the present invention has a diffraction pattern in which at least one diffraction peak is present at a position where 2θ is 20 ° to 25 °, and preferably 2θ is at least (a) 19 A diffraction peak is present at positions of 20 ° to 20 °, (b) 21 ° to 22 °, (c) 23 ° to 25 °, and (d) 29 ° to 31 °.
The powder X-ray diffraction measurement was performed using a Rigaku Electric RINT1100, setting a powder sample in a predetermined sample holder, using a wide-angle goniometer under conditions of a tube ball of Cu and a tube voltage-current of 50 kV-30 mA.

  The crystalline polyester resin A preferably has a melting point of 69 to 137 ° C. When the melting point of the crystalline polyester resin A exceeds 137 ° C., a sufficient molten state cannot be obtained near the lower limit fixing temperature, and low temperature fixability cannot be obtained. Further, when the melting point is less than 69 ° C., the heat resistant storage stability of the toner is lowered.

In the crystalline polyester resin A, the glass transition point (Tg) and the softening temperature [T (F1 / 2)] are desirably low so long as the heat resistant storage stability of the toner is not deteriorated. Is 80 to 140 ° C., preferably 80 to 125 ° C., and its softening temperature [T (F1 / 2)] is 80 to 140 ° C., preferably 80 to 125 ° C.
When the glass transition point Tg and the softening temperature [T (F1 / 2)] are higher than the above ranges, the fixing minimum temperature of the toner is increased and the low-temperature fixing property is deteriorated.
Further, when the glass transition point Tg and the softening temperature [T (F1 / 2)] are less than 80 ° C., the heat resistant storage stability is lowered.

The glass transition point (Tg) and the melting point are measured under the following conditions using TA-60WS and DSC-60 manufactured by Shimadzu Corporation.
[Measurement condition]
Sample container: Aluminum sample pan (with lid)
Sample amount: 5mg
Reference: Aluminum sample pan (alumina 10mg)
Atmosphere: Nitrogen (flow rate 50 ml / min)
[Temperature conditions]
Starting temperature: 20 ° C
Temperature increase rate: 10 ° C / min
End temperature: 150 ° C
Holding time: None Temperature drop: 10 ° C / min
End temperature: 20 ° C
Holding time: None Temperature increase rate: 10 ° C / min
End temperature: 150 ° C
The measurement was performed under the above conditions, and the measurement result was analyzed using the data analysis software (TA-60, version 1.52) manufactured by Shimadzu Corporation. The analysis method specifies a range of ± 5 ° C centering on the point showing the maximum peak on the lowest temperature side of the DrDSC curve which is the DSC differential curve of the second temperature rise, and the peak temperature is determined using the peak analysis function of the analysis software. This is determined as the melting point.
Next, the maximum endothermic temperature of the DSC curve is determined using the peak analysis function of the analysis software in the range of the peak temperature + 5 ° C. and −5 ° C. in the DSC curve. The temperature shown here corresponds to Tg.

The softening temperature [T (F1 / 2)] uses an elevated flow tester CF-500 manufactured by Shimadzu Corporation, a die diameter of 0.50 mm, a die length of 1.0 mm, a load of 10 kgf / cm ² , and a heating rate of 3 This is the melting temperature in the 1/2 method when a sample press-molded with a load of 30 kg / cm ² under the condition of ° C./min is melted and flowed out. As this flow tester, for example, an elevated type made by Shimadzu Corporation There is a flow tester CFT500 type.
The flow curve of this flow tester becomes the data shown in FIGS. 5A and 5B, from which each temperature can be read. In the figure, Ts is the softening temperature, Tfb is the outflow start temperature, and the melting temperature in the 1/2 method corresponds to the softening temperature [T (F1 / 2)] of the present invention.
[Measurement condition]
Load: 30 kg / cm ²
Temperature increase rate: 3.0 ° C / min
Die diameter: 0.50mm
Die length: 1.0mm

In the crystalline polyester resin A, the molecular weight distribution is preferably sharp from the viewpoint of low-temperature fixability, and the molecular weight is preferably a relatively low molecular weight.
As for the molecular weight of the crystalline polyester resin A, its weight average molecular weight (Mw) is 5000 to 8000, its number average molecular weight (Mn) is 1000 to 4000, and its molecular weight distribution by GPC of its o-dichlorobenzene soluble content. The Mw / Mn ratio is preferably 2-5.
The molecular weight of the crystalline polyester resin A was measured by the method described in detail in the following examples.

(Amorphous resin B)
The binder resin used in combination with the crystalline polyester resin A is a non-crystalline non-crystalline resin B, and all conventionally known resins can be used for this.
For example, styrene, α-methylstyrene, chlorostyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, Styrene resins such as styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, polyester resin, vinyl chloride resin, rosin modified maleic acid resin, phenol resin, There are epoxy resins, polyethylene resins, polypropylene resins, ionomer resins, polyurethane resins, silicone resins, ketone resins, xylene resins, petroleum resins, hydrogenated petroleum resins, and the like. Of these, styrene resins and polyester resins containing an aromatic compound as a component are preferred. Particularly preferred are polyester resins.

The amorphous polyester resin as the amorphous resin B is obtained using a known polyhydric alcohol component and a monomer containing a polyvalent carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester. It is done.
As the polyhydric alcohol and polyhydric carboxylic acid, components used in the crystalline polyester resin A can be used, and besides these, there are alkylene oxide adducts of bisphenol A, isophthalic acid, terephthalic acid, and derivatives thereof.
Usually, as a constituent monomer, it is obtained by condensation polymerization using a divalent or higher valent alcohol monomer component and a carboxylic acid monomer component such as a divalent or higher carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester as raw material monomers. In particular, the amorphous polyester can be obtained by polycondensation using at least a trihydric or higher polyhydric alcohol monomer and / or a trivalent or higher polyvalent carboxylic acid monomer or the like with the above monomer.
These resins are not limited to single use but can be used in combination of two or more.

  Preferred divalent alcohol monomer components include alkylene oxide (2 or 3 carbon atoms) oxide adduct (average number of added moles of 1 to 10) of bisphenol A, ethylene glycol, propylene glycol, 1,6-hexanediol, bisphenol A And hydrogenated bisphenol A. Preferred trivalent or higher alcohol monomer components include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like.

Examples of the divalent carboxylic acid monomer component as the acid component include various dicarboxylic acids, succinic acid substituted with an alkyl group or alkenyl group having 1 to 20 carbon atoms, anhydrides of these acids and alkyl (carbon (Equation 1-12) Esters can be mentioned, and maleic acid, fumaric acid, terephthalic acid, and succinic acid substituted with an alkenyl group having 2 to 20 carbon atoms are preferred. Preferred trivalent or higher carboxylic acid components are 1,2,4-benzenetricarboxylic acid (trimellitic acid), its acid anhydride, alkyl (C 1-12) ester, and the like.
Other usable carboxylic acid components include isophthalic acid, terephthalic acid, and derivatives thereof.

  The manufacturing method of polyester is not specifically limited, It can manufacture by esterification reaction or transesterification reaction combining said each monomer. When polymerizing the raw material monomer, a commonly used esterification catalyst such as dibutyltin oxide may be appropriately used in order to accelerate the reaction.

  Among these, as described above, the polyester component is condensed using a divalent or higher alcohol monomer component and a divalent or higher carboxylic acid monomer such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester as a raw material monomer. It can be obtained by polymerization.

  Although the molecular structure of the amorphous polyester resin as the amorphous resin B is not limited, the alcohol component is at least one of bisphenol A propylene oxide adduct and bisphenol A ethylene oxide adduct, and the acid component is carbon. It is desirable to have an unsaturated double bond between them, and it is particularly desirable to contain at least fumaric acid, maleic acid and derivatives thereof.

The molecular weight of the amorphous polyester resin used as the amorphous resin B in the present invention is the weight average molecular weight (Mw) of 3000 to 100,000 and the number average molecular weight (Mn) in the molecular weight distribution by GPC of the THF-soluble component. Is preferably 1500 to 4000 and its Mw / Mn ratio is 2 to 50.
The molecular weight distribution is based on a molecular weight distribution chart in which the horizontal axis is log (M: molecular weight) and the vertical axis is weight%. In the case of the polyester resin B used in the present invention, it is preferable to have a molecular weight peak in the range of 2.5 to 4.5 (% by weight) in this molecular weight distribution diagram.
The molecular weight of the amorphous polyester resin used as the amorphous resin B was measured by the method described in detail in the following examples.

In the amorphous polyester resin used as the amorphous resin B, the glass transition point Tg and the softening temperature [T (F1 / 2)] are desirably low as long as the heat resistant storage stability of the toner is not deteriorated. The Tg is 45 to 75 ° C, preferably 50 to 70 ° C, and the softening temperature [T (F1 / 2)] is 90 to 150 ° C, preferably 90 to 130 ° C.
When Tg and the softening temperature [T (F1 / 2)] are higher than the above ranges, the lower limit fixing temperature of the toner is increased, so that the low temperature fixability of the toner is deteriorated.
The glass transition point (Tg) and softening temperature [T (F1 / 2)] of the amorphous polyester resin as the amorphous resin B were measured in the same manner as in the case of the crystalline polyester resin A.

The crystalline polyester resin A and the amorphous resin B are substantially incompatible with each other, and even if both of them are contained in the binder resin, they should be present in the toner as being incompatible with each other. Can do.
The crystalline polyester resin A and the amorphous resin B being in an incompatible state means that the crystalline polyester resin A remains in the toner and is in a phase-separated state. The state means a state in which no crystal structure portion remains.

When the crystalline polyester resin A and the non-crystalline resin B exist in an incompatible state, that is, in a phase-separated state, the thermal characteristics specific to the resin can be effectively expressed respectively.
That is, the amorphous resin B having a high softening temperature [T (F1 / 2)] can increase the elasticity of the toner and improve the hot offset resistance of the toner, while the low softening temperature [T ( The low-temperature fixability can be improved by the crystalline polyester resin A having F1 / 2)].

Whether or not the crystalline polyester resin A and the amorphous polyester resin as the amorphous resin B are present in a phase separated state in the toner can be confirmed by any of the following methods.
(1) The presence or absence of the formation of a phase-separated domain structure can be confirmed by measuring the endothermic peak due to the first temperature increase of the DSC of the toner. In the DSC endothermic peak measurement, there are at least the endothermic peaks (B) and (A) attributed to the amorphous polyester resin B and the crystalline polyester resin A, respectively, and the endothermic peaks attributed to the amorphous polyester resin B ( B) has a peak top in the range of 40 to 70 ° C, and the endothermic peak (A) attributed to the crystalline polyester resin A has a peak top in the range of 80 to 140 ° C.

(2) The presence or absence of the formation of a phase separation structure can be confirmed by X-ray diffraction pattern measurement using a toner powder X-ray diffractometer. This is attributed to the crystalline polyester resin A because the crystalline polyester resin A retains crystallinity and is present in the toner in a phase-separated state with the amorphous polyester resin B in the case of the toner of the present invention. Are present at least at 2θ = 20 ° to 25 °.
When the phase-separated structure is not formed, the crystalline structure of the crystalline polyester resin A is not maintained and is compatible with the amorphous polyester resin B, so that a diffraction peak attributed to the crystalline polyester resin A does not appear. .

(Release agent)
As the release agent used in the toner in the present invention, in addition to the above-mentioned waxes, all known ones can be used, and in particular, desorbed fatty acid type carnauba wax, polyethylene wax, montan wax and oxidized rice wax are used alone or in combination. Can be used in combination. The carnauba wax is preferably a microcrystalline one, having an acid value of 5 or less and a particle size of 1 μm or less when dispersed in a toner binder. The montan wax generally refers to a montan wax refined from minerals, and like a carnauba wax, it is microcrystalline and preferably has an acid value of 5 to 14. The oxidized rice wax is obtained by air-oxidizing rice bran wax, and the acid value is preferably 10-30. The reason is that these waxes are finely dispersed in the toner binder resin of the present invention, so that it is easy to obtain a toner excellent in offset prevention, transferability and durability as described later. These waxes can be used alone or in combination of two or more.
As other mold release agents, any conventionally known mold release agents such as solid silicone wax, higher fatty acid higher alcohol, montan ester wax, polyethylene wax and polypropylene wax can be mixed and used.

The Tg of the release agent used in the toner of the present invention is preferably 70 to 90 ° C. If the temperature is less than 70 ° C., the heat resistant storage stability of the toner is deteriorated. If the temperature exceeds 90 ° C., the release property at low temperature is not exhibited, the cold offset resistance is deteriorated, and the paper is wound around the fixing machine.
In addition, as the release agent, two or more of the above-mentioned ones can be mixed and used, but the softening temperature [T (F1 / 2)] of the crystalline polyester resin A contained in the binder resin By using at least one kind of wax having a lower melting point, the releasability near the lower limit of fixing temperature can be reliably obtained, and the above-described cold offset and the wrapping of paper around the fixing belt, etc. are prevented. This is preferable.
The amount of these release agents used is 1 to 20% by weight, preferably 3 to 10% by weight, based on the toner resin component. If it is less than 1% by weight, the effect of preventing offset is insufficient, and if it exceeds 20% by weight, transferability and durability are deteriorated.

(Coloring agent)
As the colorant used in the color toner of the present invention, known pigments and dyes capable of obtaining toners of yellow, magenta, cyan and black colors can be used.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, and Tartrazine Lake. Can be mentioned.

Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of the green pigment include chrome green, chromium oxide, pigment green B, and malachite green lake.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
These can use 1 type (s) or 2 or more types.

(Charge control agent)
The color toner of the present invention can contain a charge control agent in the toner as needed.
For example, nigrosine, azine dyes containing an alkyl group having 2 to 16 carbon atoms (Japanese Patent Publication No. 42-1627), basic dyes such as C.I. I. Basic Yellow 2 (C.I. 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (C.I. 45160), C.I. I. Basic Red 9 (C.I. 42500), C.I. I. Basic Violet 1 (C.I. 42535), C.I. I. Basic Violet 3 (C.I. 42555), C.I. I. Basic Violet 10 (C.I. 45170), C.I. I. Basic Violet 14 (C.I. 42510), C.I. I. Basic Blue 1 (C.I. 42025), C.I. I. Basic Blue 3 (C.I. 51005), C.I. I. Basic Blue 5 (C.I. 42140), C.I. I. Basic Blue 7 (C.I. 42595), C.I. I. Basic Blue 9 (C.I. 52015), C.I. I. Basic Blue 24 (C.I. 52030), C.I. I. Basic Blue 25 (C.I. 52025), C.I. I. Basic Blue 26 (C.I. 44045), C.I. I. Basic Green 1 (C.I. 42040), C.I. I. Basic Green 4 (C.I. 42000) and the like and lake pigments of these basic dyes, C.I. I. Solvent Black 8 (CI. 26150), quaternary ammonium salts such as benzoylmethyl hexadecyl ammonium chloride, decyl trimethyl chloride, or dialkyl tin compounds such as dibutyl or dioctyl, dialkyl tin borate compounds, guanidine derivatives, containing amino groups Polyamine resins such as vinyl polymers, condensation polymers containing amino groups, Japanese Patent Publication No. 41-20153, Japanese Patent Publication No. 43-27596, Japanese Patent Publication No. 44-6397, Japanese Patent Publication No. 45-26478 Metal complex salts of monoazo dyes described, Japanese Patent Publication No. 55-42752, Japanese Patent Publication No. 59-7385, salicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid Zn, Al, Co, Cr , Fe, etc. Metal complex, a copper phthalocyanine pigment obtained by sulfonation, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like. Naturally, color toners other than black should avoid the use of charge control agents that impair the target color, and white metal salts of salicylic acid derivatives are preferably used.
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
As the external additive for assisting the fluidity, developability and chargeability of the colored particles obtained in the present invention, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 mμ to 2 μm, and particularly preferably 5 mμ to 500 mμ. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight.
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, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
In addition, polymer fine particles, such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, methacrylate esters, acrylate copolymers, polycondensation systems such as silicone, benzoguanamine, and nylon, thermosetting Examples thereof include polymer particles made of a resin.
Such a fluidizing agent 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. It is done.

(Toner manufacturing method)
As a method for producing the toner of the present invention, a conventionally known method such as a melt kneading-pulverizing method or a polymerization method can be applied.
In the manufacturing process,
(1) Step of melt-kneading the binder resin and the inorganic fine particles (2) Step of pulverizing the melt-kneaded toner composition (3) Step of externally adding second inorganic fine particles (4) Predetermined It is preferable to have a classification step for obtaining a particle size and to perform the (4) classification step after the (3) external addition step in order to increase the fluidity of the particles and increase the classification accuracy and yield. Moreover, it is preferable from the viewpoint of cost that the fine powder to be replicated in the classification step is side-kneaded as a raw material of (1).

In view of the recent demand for higher image quality, the toner has a weight average particle diameter (D4) of preferably 3 to 8 μm, more preferably 4 to 7 μm, in order to reproduce minute dots of 600 dpi or more. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent.
When the weight average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties tend to occur.
When the weight average particle diameter (D4) exceeds 8 μm, it is difficult to suppress scattering of characters and lines.
The ratio (D4 / D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is preferably in the range of 1.00 to 1.40, more preferably 1.05 to 1. 30.
The closer (D4 / D1) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

  In the full-color image forming method for forming a multicolor image by superimposing different color toner images, an image is formed with only one color of black toner, so that it is not necessary to superimpose different color toner images. The amount of toner deposited on the paper is large. In other words, since the amount of toner to be developed, transferred and fixed increases, the above-mentioned problems such as lower transfer efficiency, lower blade cleaning performance, scattering of characters and lines, background fogging, etc. are likely to occur. Management of the ratio (D4 / D1) of the diameter (D4) and the weight average particle diameter (D4) to the number average particle diameter (D1) is important.

Next, a method for measuring the particle size distribution of toner particles will be described.
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 an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the weight and number of toner particles or toner using a 100 μm aperture as an aperture. Calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) 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 .35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 16.00 to less than 20.20 μm; 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.

  Since the toner of the present invention contains crystalline polyester, the volume resistivity value LogR tends to be lower than that of toner not containing crystalline polyester. This is a phenomenon derived from the fact that since the crystalline polyester has crystallinity, its volume resistivity is lower than that of an amorphous polyester resin. The LogR of the toner of the present invention is preferably 10.5 to 11.2 LogΩ · cm, and particularly preferably 10.7 to 11.15 LogΩ · cm. Since the LogR increases as the crystalline polyester content decreases or when a high kneading share is applied to the melt blending range, the LogR is adjusted by the crystalline polyester content and the kneading share at the time of melt kneading.

  When the LogR of the toner is smaller than 10.5 LogΩ · cm, the conductivity becomes high, thereby causing a charging failure, and there is a tendency to increase background contamination and toner scattering. In addition, an abnormal image is generated due to electrostatic offset or the like, and a high-quality image cannot be obtained stably. Further, when the LogR of the toner exceeds 11.2 LogΩ · cm, the resistance increases, and the charge amount increases and the image density tends to decrease.

The volume specific resistance LogR of the toner was measured as follows.
As a sample, 3 g of toner was pressed for 1 minute under a load of 6 t with an automatic pellet molding machine (Type M No. 50 BRP-E; manufactured by MAEKAWA TESTING MACHINE CO.) To produce 40 mmφ (thickness: about 2 mm) pellets. This is set on SE-70 type solid electrode (manufactured by Ando Electric Co., Ltd.), and LogR when AC of 1 kHz is applied between the electrodes is TR-10C type dielectric loss measuring instrument, WBG-9. Measurement was made with a measuring instrument comprising an oscillator and a BDA-9 equilibrium point detector (both manufactured by Ando Electric Co., Ltd.), and the volume specific resistance value LogR of the toner was determined. The measurement was performed in an environment with a room temperature of 25 ° C. and a humidity of 50%.

The toner of the present invention preferably has a glass transition point (Tg) in the range of 35 to 70 ° C. When the glass transition point is less than 35 ° C., hot offset resistance and heat-resistant storage stability deteriorate, and when it is 70 ° C. or more, low-temperature fixability deteriorates.
The glass transition point (Tg) was measured in the same manner as for the crystalline polyester resin A.

[Two-component developer]
When the toner of the present invention is used as a two-component developer, it may be used by mixing with a magnetic carrier. The carrier to toner content ratio in the developer is 1 to 10 parts by weight of toner with respect to 100 parts by weight of carrier. Is preferable, and it is more preferable to set it as the range of 3-9 weight part. As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle diameter of about 20 to 200 μm can be used. Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene-acrylic copolymer resins, Halogenated olefin resins such as vinyl chloride, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoropropylene Resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinyl Fluoro terpolymers, and silicone resins terpolymers etc. of vinylidene fluoride and non-fluorinated monomer. Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 μm or less. When the average particle diameter is larger than 1 μm, it becomes difficult to control electric resistance.

[Single component developer]
The toner of the present invention can also be used as a one-component magnetic toner that does not use a carrier or a non-magnetic toner.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the following, “parts” means parts by weight, and “%” means percent by weight.

<Production of crystalline polyester A>
Polyesters A1 to A4 were charged with 4000 g of the composition shown in Table 1 and 4 g of hydroquinone in a 5 L four-necked round bottom flask equipped with a thermometer, stirrer, condenser and nitrogen gas inlet tube. It was set in a heater, nitrogen gas was introduced from a nitrogen gas introduction tube, and the temperature was raised in a state where the inside of the flask was maintained in an inert atmosphere. The temperature was maintained at 160 ° C. for 5 hours, and then reacted at 200 ° C. for 1 hour. Thereafter, each polyester was reacted for 1 hour at 8.3 kPa.

  Table 1 shows components of each polyester A1 to A4, and Table 2 shows physical property values of each polyester A1 to A4. BPA / EO shown in Table 1 represents an ethylene oxide adduct of bisphenol A (2.2 mol adduct), and BPA / PO represents a propylene oxide adduct of bisphenol A (2.2 mol adduct). Indicates.

  In addition, what has crystallinity has a diffraction peak in the X-ray-diffraction pattern by a powder X-ray-diffraction apparatus at the position of at least 2 (theta) = 19-20 degrees, 21-22 degrees, 23-25 degrees, 29-31 degrees. It has appeared. Those having an estimated molecular formula are those in which the presence of the molecular structure of the general formula (1) has been confirmed by solid-state C13 NMR.

<Production of amorphous polyester B>
Polyester B-H1 and B-L1 were prepared by placing 4000 g of the composition shown in Table 3 into a 5-L four-necked round bottom flask equipped with a thermometer, stirrer and condenser, and setting the flask in a mantle heater. Then, 4 g of dibutyltin oxide was added, the temperature was raised, the temperature was kept at 220 ° C., and the reaction was carried out for 8 hours. Then, the reaction was carried out at 8.3 kPa until a predetermined softening point was reached, thereby obtaining each polyester.

  Table 3 shows the components of each polyester B-H1 and B-L1, and Table 4 shows the physical property values thereof. BPA / EO shown in Table 3 represents an ethylene oxide adduct of bisphenol A (2.2 mol adduct), and BPA / PO represents a propylene oxide adduct of bisphenol A (2.2 mol adduct). Indicates.

<Toner Production Example 1>
Crystalline polyester resin A1 ... 15 parts Amorphous polyester resin B-H1 ... 55 parts Amorphous polyester resin B-L1 ... 30 parts Salicylic acid Zr salt (Hodogaya Chemical TN-105) ... 1 Part Desorbed fatty acid type carnauba wax (Tg: 83 ° C.) 5 parts Carbon black (Mitsubishi Chemical # 44) 10 parts After thoroughly stirring and mixing the above toner constituent materials in a Henschel mixer, biaxial Melt kneading was carried out using an extruder. Regarding the kneading conditions, as a result of setting the temperature of the kneader to knead the kneaded material at a low temperature (minimum temperature within the range where the kneaded material is in a molten state), the kneading material is mixed at the kneader outlet. The temperature of the kneader was set so that the temperature of the smelted product was 120 ° C. Next, the kneaded product was coarsely pulverized to a particle size of 1 mm or less using an AP pulverizer manufactured by Hosokawa Micron Co., and then finely pulverized using a turbo mill manufactured by Turbo Industries Co., Ltd. to obtain a toner base having a weight average particle size of 6.5 μm. The obtained toner base was classified and 0.5 wt% of hydrophobic silica (average primary particle size 20 nm, bulk density 0.15 mg / cm ² ) and 0.3 wt% of titanium oxide were added and mixed to obtain the final toner 1. . The toner 1 has a LogR of 10.9 LogΩ · cm, SF-1 of 159, SF-2 of 160, and a ratio (D4 / D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is 1. 21.

<Toner Production Example 2>
Toner 2 was prepared in the same manner as in Toner Production Example 1 except that Polyester A1 was changed to Polyester A2 in Toner Production Example 1.
The Log R of toner 2 was 11.15 Log Ω · cm, SF-1 was 156, SF-2 was 159, and D4 / D1 was 1.22.

<Toner Production Example 3>
Toner 3 was prepared in the same manner as in Toner Production Example 1 except that Polyester A1 was changed to Polyester A3 in Toner Production Example 1.
Log R of toner 3 was 10.9 Log Ω · cm, SF-1 was 157, SF-2 was 158, and D4 / D1 was 1.20.

<Toner Production Example 4>
Toner 4 was prepared in the same manner as in Toner Production Example 1 except that Polyester A1 was changed to Polyester A4 in Toner Production Example 1.
Log R of toner 4 was 10.9 Log Ω · cm, SF-1 was 160, SF-2 was 163, and D4 / D1 was 1.22.

<Toner Production Example 5>
Toner 5 was prepared in the same manner as in Toner Production Example 1 except that the formulation was changed to the following.
Crystalline polyester resin A1 ... 77 parts Amorphous polyester resin B-H1 ... 15 parts Amorphous polyester resin B-L1 ... 8 parts Salicylic acid Zr salt (Hodogaya Chemical TN-105) ... 1 Part Desorbed fatty acid type carnauba wax (Tg: 83 ° C.) 5 parts Carbon black (Mitsubishi Chemical # 44) 10 parts Toner 5 has a LogR of 10.2 LogΩ · cm, SF-1 of 154, SF -2 is 159 and D4 / D1 is 1.22.

<Toner Production Example 6>
Toner 6 was prepared in the same manner as in Toner Production Example 1 except that the formulation was changed to the following.
Crystalline polyester resin A1 ... 2.5 parts Amorphous polyester resin B-H1 ... 67.5 parts Amorphous polyester resin B-L1 ... 30 parts Salicylic acid Zr salt (Hodogaya Chemical TN-105) ... 1 part Desorbed fatty acid type carnauba wax (Tg: 83 ° C) ... 5 parts Carbon black (Mitsubishi Chemical # 44) 10 parts Toner 6 has a LogR of 11.1 LogΩ · cm, SF-1 of 158, SF-2 is 160 and D4 / D1 is 1.20.

<Example of carrier production>
(I) Core material: Cu—Zn ferrite particles (volume average diameter: 45 μm) 5000 parts (ii) Coating material Toluene: 450 parts Silicone resin SR2400
(Toray Dow Corning Silicone, non-volatile content 50%) ・ ・ ・ 450 parts Aminosilane SH6020
(Toray / Dow Corning / Silicone) 10 parts Carbon black 10 parts The above coating material is dispersed with a stirrer for 10 minutes to prepare a coating solution, and the coating solution and the core material are rotated in a fluidized bed. The coating solution was applied to the core material by applying a coating apparatus that coats while forming a swirling flow and provided with a type bottom plate disk and a stirring blade.
Next, the obtained carrier was baked in an electric furnace at 250 ° C. for 2 hours, and the carrier particles of the production example (saturation magnetization 65 emu / g when 3 kOe was applied, residual magnetization 0 emu / g when 3 kOe was applied, specific resistance 3.2). × 10 ⁸ Ω · cm, volume average diameter 45 μm) was obtained.

<Examples of developer production>
Each toner 1 according to toner production examples 1 to 6 was prepared by mixing 2.5 parts of the toner obtained in toner production examples 1 to 6 and 97.5 parts of the carrier obtained in the carrier production example with a Turbler mixer. Developers (1) to (6) corresponding to -6 were obtained.

[Method for evaluating resin properties]
<Measurement of molecular weight by GPC>
(1) Measurement of molecular weight of amorphous polyesters B-H1, B-L1 and crystalline polyester A2 by GPC The column was stabilized in a heat chamber at 40 ° C., and 1 ml of THF as a solvent was added to the column at this temperature per minute. Then, 50 to 200 μl of a THF sample solution of the resin is injected and measured. The THF sample solution of the resin was prepared by stirring a THF solution having a resin concentration of 0.5% by weight with a ball mill at room temperature for 24 hours, and then filtering with a 0.2 μm hole diameter membrane filter manufactured by Toyo Filter Paper Co., Ltd. is there. Waters GPC-150C can be used as a measuring device, and Shodex KF801-807 can be used as a column. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Or Toyo Soda Kogyo Co., Ltd. having a molecular weight of ^{6 × 10 2, 2.1 × 10} 3, 4 × 10 3, 1.75 × 10 4, 5.1 × 10 4, 1.1 × 10 5, 3.9 It is suitable to use x10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

(2) Measurement of molecular weight by GPC of crystalline polyesters A1 and A3 to A4 GPC (gel permeation chromatography) is measured as follows.
The column was stabilized in a heat chamber at 145 ° C., and O-dichlorobenzene containing 0.3% BHT as an eluent was allowed to flow through the column at this temperature at a flow rate of 1 ml / min to a sample concentration of 0.3% by weight. Measurement is performed by injecting 50 to 200 μl of 140 ° C. O-dichlorobenzene solution of the prepared resin. Waters 150CV type can be used as a measuring instrument, and Shodex AT-G + AT-806MS (two) can be used as a column.

[Molecular structure of resin]
Using solid C13-NMR (FT-NMR SYSTEM JNM-α400 manufactured by JEOL Ltd.), observation nucleus C13, reference material adamantane, integration number 8192 times, pulse series CPMAS. IRMOD: IRLEV, observation frequency 100.4 MHz, OBSET: 134500 Hz, POINT: 4096, PD: 7.0 sec, SPIN 6088 Hz, and molecular structure estimation is performed by Chem Draw Pro Ver. 4.5.
The following two measurements were used in combination to confirm the results of molecular structure analysis by solid C13-NMR.
(A) A sample is measured by a Fourier transform infrared spectrophotometric (FT-IR) transmission method, and the structure is estimated from standard spectrum comparison.
Measuring machine: Nicolet Magna 850
Measurement range: 4000 to 400 cm-1
Standard sample: KBr
(B) Thermal decomposable organism structure estimation by pyrolysis gas chromatogram mass spectrometer Measuring instrument: Shimadzu Corporation GC-17A, Shimadzu CR-4A
Thermal decomposition temperature: Nippon Analytical Industry JHB-3S
Thermal decomposition temperature: sample heating temperature × time is 590 ° C. × 4 seconds Column: DB-5 (J and W Co.) L = 30 m, I.V. D = 0.25 mm,
Film = 0.25mm
Column temperature: raised from 50 ° C. (holding time 1 minute) to 300 ° C. at 10 ° C./min Injection temperature: 320 ° C.
Carrier gas pressure: From 90 kPa (holding time 2 minutes) to 2 kPa / min, 150
Boost to kPa Detector: FID

[Shape factors SF-1, SF-2]
The shape factor SF-1 is 100 images of toner particles magnified by a magnification of 500 using an electron microscope (for example, FE-SEM (S-800) manufactured by Hitachi, Ltd., and the same applies hereinafter). Randomly sampled and the image information is sent via an interface to an image analyzer [eg, Nexus NEW CUBE ver. 2.5 (manufactured by NEXUS), Luzex III (manufactured by Nicole) and the like, and so on. It was calculated by the following formula (1).
The shape factor SF-2 is obtained by randomly sampling 50 toner particle images magnified to 3500 times using an electron microscope, and introducing the image information into an image analysis apparatus via an interface for analysis. Calculated from (2).
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
SF-2 = {(PERI) ² / AREA} × (100π / 4) Expression (2)

  In the following, fixing devices used for evaluation of fixing performance in Examples and Comparative Examples, and evaluation methods thereof are shown.

(Belt fixing device 1)
Fixing performance was evaluated using an induction heating type fixing device shown in FIG. The fixing conditions were a fixing pressure of 2.5 kgf / cm ² and a fixing nip time of 80 msec. The evaluation results are shown in Table 5.

(Belt fixing device 2)
In FIG. 2, instead of heating by the induction coil 14, a fixing performance was evaluated using a belt fixing device 2 in which a halogen heater was installed inside the cylindrical portion of the opposing roller 252 and heated by this halogen heater. . As in the case of the belt fixing apparatus 1, the fixing conditions were set at a fixing pressure of 2.5 kgf / cm ² and a fixing nip time of 80 msec.
The evaluation results are shown in Table 5.

The fixing performance evaluation method is as follows.
(1) Evaluation Method of Wrapping During Continuous Passing An unfixed image in which 1.0 ± 0.1 mg / cm ² of toner has been developed on the entire surface of A4 size paper is continuously passed by the above-described fixing machine and fixed. Evaluation was made by visually confirming whether or not the paper was wrapped around the fixing belt. “◯” indicates that there is no winding, “Δ” indicates that there is a slight level of winding, and “×” indicates that the winding and sticking to the fixing belt. The temperature was controlled so that the surface temperature of the fixing roller was 200 ° C., and NBS Ricoh copy printing paper 55-A4Y was used as the paper, which is a thin paper that easily wraps around.
(2) Fixing Lower Limit Temperature An unfixed image in which toner of 1.0 ± 0.1 mg / cm ² is developed on the NBS Ricoh Copy Printing Paper 55-A4Y is heated at a fixing roller temperature of 5 ° C. The fixed image at each temperature was rubbed 10 times with a clock meter equipped with a sand eraser, the Macbeth densitometer image density was measured before and after the rubbing, and the fixing rate was calculated by the following formula (3). Asked.
Fixing rate (%) = (Image density after 10 times of sand eraser) / (Previous image density) × 100
(3)
The temperature at which a fixing rate of 70% or more was achieved was defined as the minimum fixing temperature.

As can be seen with reference to Table 5, in Examples 1 to 5 according to the present invention, excellent low-temperature fixability, and there is no occurrence of paper wrapping around the fixing belt 253 even during continuous passage of A4 size paper. A stable image formation state was obtained.
On the other hand, in Comparative Example 1, since no means for suppressing overshoot is taken in the fixing device, the occurrence of hot offset on the fixing belt 253 and the melting of the toner from the belt cleaning roller 261 lead to the fixing belt 253. The paper wrapping phenomenon was observed.
In Comparative Examples 2 and 3, since the resin having crystallinity was not contained, the low temperature fixability was inferior.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. 1 is an overall configuration diagram of a fixing device according to the present invention. 2 is a longitudinal sectional view of a fixing belt 253 used in the fixing device according to the present invention. FIG. FIG. 6 is a cross-sectional view illustrating a configuration of an upper half of a fixing belt wound around a counter roller and a counter roller of a fixing device according to a second embodiment used in the image forming apparatus of the present invention. It is a figure which shows the flow curve of a flow tester.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 18 Image forming means 20 Tandem type image forming device 21 Exposure device 22 Secondary transfer device 24 Secondary transfer belt 25 Fixing device 251 Fixing roller 252 Opposing roller (heating roller)
252a Core metal 252b Magnetic shunt alloy layer 253 Fixing belt 253a Base material 253b Elastic layer 253c Release layer 254 Induction coil (induction heating means)
255 Fixing nip portion 256 Pressure roller 257 Excitation core 258 Temperature sensor 259 Control device 260 Guide plate 261 Belt cleaning roller 40 Photoconductor 62 Primary transfer means 100 Copying device main body 200 Paper feed table 300 Scanner 400 Automatic document feeder (ADF)

Claims (15)

At least an image carrier that carries a latent image;
Developing means for developing the latent image with toner;
Transfer means for transferring a toner image on the surface of the image carrier;
In an image forming apparatus comprising: a fixing unit that fixes the toner image by heating and pressing.
The toner is a toner containing at least a binder resin including a crystalline polyester resin and an amorphous resin, and a colorant.
The fixing unit is a fixing device having an electromagnetic wave generating unit and an electromagnetic induction heating element that generates heat when a magnetic field generated by the electromagnetic wave generating unit is applied.
The electromagnetic induction heating element contains a magnetic shunt alloy on the surface or inside thereof. The image forming apparatus according to claim 1.
The fixing unit includes at least two rotating members, and an endless traveling moving member that is wound between the rotating members and moves.
The image forming apparatus, wherein the electromagnetic induction heating element is the traveling moving member or the rotating member. The image forming apparatus according to claim 1, wherein
The image forming apparatus includes a cleaning member that contacts the travel moving member. The image forming apparatus according to any one of claims 1 to 3,
The electromagnetic induction heating element is a traveling member;
The travel forming member is formed of a support layer and a release layer, and the support layer contains the magnetic shunt alloy. The image forming apparatus according to claim 1,
The travel moving member is used at a surface temperature of 200 ° C. or less. The image forming apparatus according to claim 1,
The crystalline polyester resin has a melting point of 69 to 137 ° C. The image forming apparatus according to claim 1,
Content of the said crystalline polyester resin in the said binder resin is 2.5-50 weight part with respect to 100 weight part of all the binder resin. The image forming apparatus characterized by the above-mentioned. The image forming apparatus according to claim 1,
The crystalline polyester has a softening temperature [T (F1 / 2)] of 80 to 140 ° C.,
The image forming apparatus, wherein the toner contains at least one wax having a melting point lower than the softening temperature [T (F1 / 2)] of the crystalline polyester. The image forming apparatus according to claim 1,
The image forming apparatus, wherein Tg of the toner is 35 to 70 ° C. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the toner contains a magnetic material. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the toner is mixed with a resin-coated magnetic carrier. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the magnetic shunt alloy is an iron-nickel alloy. The image forming apparatus according to claim 1,
The image forming apparatus includes a process cartridge in which at least an image carrier and a developing unit are integrally supported and are detachably formed in the image forming apparatus. A step of forming an electrostatic latent image on the image bearing member, a step of developing the electrostatic latent image with a developer containing toner to form a toner image, a step of transferring the toner image onto the transfer target,
A fixing process in which a toner image on a transfer medium is heated and pressed by a fixing member and fixed on a recording medium.
The electrostatic image developing toner used in the development step is a toner containing at least a binder resin including a crystalline polyester resin and an amorphous resin, and a colorant,
In the fixing step, a fixing device having an electromagnetic wave generating unit and an electromagnetic induction heating element that generates heat when a magnetic field generated by the electromagnetic wave generating unit is applied is used.
The electromagnetic induction heating element contains a magnetic shunt alloy on the surface or inside thereof. 14. The image forming method according to claim 2, wherein the image forming method is applied to the image forming apparatus according to claim 2.

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