JP2007155852A - Color image forming apparatus and color image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of providing a solid image with which retouching using an oily ink can be smoothly performed relating to the fixed solid image having lightness of a specified or higher value and to provide a method for forming a color image. <P>SOLUTION: The image forming apparatus 100 comprises image carriers 40 carrying electrostatic latent images corresponding to respective colors Y, M, C and K, developing devices 4 of respective colors developing the electrostatic latent images of the respective colors on the latent image carriers 40, a transfer apparatus 22 for simultaneously secondarily transferring the toner images primarily transferred onto an intermediate transfer member 10 from the image carriers 40 to a member to be transferred, and a fixing device 25 for fixing the toner on the member to be transferred. In the image forming apparatus, the toner deposition amount obtained by the fixing device 25 is 0.4 mg/cm<SP>2</SP>, and the fall start point in the methanol hydrophobicity of the toner forming the extreme surface layer of the toner image of ≥50 in an L* value is 28≤methanol/(methanol+water)(vol.%). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a full-color image forming apparatus using an electrophotographic system such as a printer, a facsimile machine, and a copying machine, and a color image forming method using the same, and more specifically, an image is formed with an intermediate transfer member such as an intermediate transfer belt interposed. A color image forming apparatus for forming an image through each transfer process of primary transfer for transferring a toner image from a carrier to an intermediate transfer body and secondary transfer for transferring a primary transfer image on the intermediate transfer body to a transfer material, and the apparatus The present invention relates to a color image forming method to be used.

  Conventionally, in a color image forming apparatus such as a color printer or a copying machine that forms a color image using an electrophotographic recording method, an electrostatic latent image is formed on an image carrier based on image data of each color, This is developed with each color toner, and the toner image on the image carrier is electrostatically transferred to a transfer member to form a full-color toner image.

With the demand from the market, in recent years, the use of color image forming apparatuses such as color copiers and color printers has increased, and the use of color fixed images has also expanded rapidly.
For example, when a fixed image is used in a meeting or the like, it may be necessary for the user to perform writing on the image using a writing instrument such as a ballpoint pen or a mechanical pencil. In this case, if the output image is formed in monochrome alone, it is difficult to discriminate characters or the like added on the image, so that it is rarely applied on the image in reality.
On the other hand, when the output image is formed in full color by superimposing a plurality of toners, even if characters or figures are written on the image, the added characters can be distinguished relatively easily. .
For this reason, on an image formed in full color, the frequency of rewriting on the output image is overwhelmingly higher than that of a monochrome image.

By the way, if the above-described color-fixed image is a halftone image, there is a non-image forming area of 30 to 70% per unit area on the paper surface, so writing on this image is relatively easy. be able to.
On the other hand, in the case of a so-called solid image in which the image forming area per unit area is 90% or more, the paper surface is almost completely covered with the binder resin. It is difficult to add to
However, if this solid image is formed to a certain degree of high brightness, it is possible to discriminate characters and figures after being added to the image. The demand for writing is relatively high.

By the way, as described above, since the solid image is almost completely covered with the toner as described above, when writing on the image, the solid image and the toner that forms the surface of the fixed image are added. Affinity with the ink used for the ink is important.
In general, there are two types of ink used for writing instruments: oily and water-based, but the binder resin that is the main component of the toner is usually a hydrophobic resin such as polyester or styrene-acrylic. These resins are low in affinity with water-based inks. For this reason, it is not suitable to write on a solid image using water-based ink.

For example, in Patent Document 1, a thermo-pressure fixing composed of a heat-meltable core material containing at least a thermoplastic resin and a colorant and an outer shell made of a hydrophilic resin provided so as to cover the surface of the core material. In the capsule toner, the storage elastic modulus of the toner at a frequency of 100 rad / sec is 1 × 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² at 120 ° C. and 5 × 10 ³ to 1 × 10 ⁵ dyn at 200 ° C. / heat-and-pressure fixing capsule toner which is characterized in that cm ^2, and and a manufacturing method thereof are disclosed.
When a solid image is formed using a toner having a surface composed of a hydrophilic resin as disclosed in Patent Document 1, the affinity between the toner and water-based ink is maintained. Although it is possible to perform writing with ink, generally used toner is toner mainly composed of hydrophobic resin, and toner using hydrophilic resin as disclosed in Patent Document 1 A small percentage is used.
In recent years, in order to perform oilless fixing, many toners contain a release agent such as wax, and when a solid image is formed using such toner, a fixed image is obtained. Since many release agents are present on the surface, it is more difficult to write using water-based ink.
For this reason, when writing on a solid image, it is common to use oil-based ink, and it is important that the toner on the surface of the color image has high affinity with the oil-based ink. It is.

By the way, in full-color image formation, toners of four colors of yellow, cyan, magenta, and black are generally used. The characteristics of these toners slightly differ depending on the constituent material and surface composition of the toner particles.
When the fixed image is a solid image, if the toner that forms the surface of the fixed image has low affinity with the ink used for writing, the image can be smoothly applied to the image. The problem of being unable to do so occurs.

JP-A-10-228130

  Therefore, the present invention has been made in view of the above-mentioned problems, and its problem is to provide a solid image that can be smoothly applied with oil-based ink, regarding a fixed image having a lightness of a certain value or more. Another object is to provide a color image forming apparatus and a color image forming method.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. The present invention forms an image carrier that carries an electrostatic latent image corresponding to each color of yellow, cyan, magenta, and black, and develops the electrostatic latent image of each color on the image carrier to form a toner image. A developing device corresponding to each color toner, and a transfer device that primarily transfers a toner image on the image carrier to an intermediate transfer member and then secondary-transfers the toner images on the intermediate transfer member collectively to a transfer target; A color image forming apparatus having a fixing device for fixing a toner on the transfer medium to form a toner image, wherein the toner image obtained by the fixing device and having an L ^* value of 50 or more, The color image forming apparatus is characterized in that the lowering start point in the methanol hydrophobicity of the toner forming the outermost layer is 28 ≦ methanol / (methanol + water) (volume%). (However, the lightness L ^* is a value of a fixed image in which the toner is uniformly adhered on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. )
2. The color image forming apparatus according to the present invention includes: In the invention described in Item 1, it is preferable that the toner image obtained by the fixing device and having an L ^* value of 50 or more includes at least yellow toner. (However, the lightness L ^* is a value of a fixed image in which toner is uniformly deposited on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. )
3. The color image forming apparatus according to the present invention includes: Or 2. The plurality of developing devices are preferably arranged in a tandem type, and the order of arrangement of the developing devices is preferably a yellow developing device and a fourth developing device.
4). In addition, the color image forming apparatus of the present invention includes: In the invention described in item 1, it is preferable that the order of arrangement of the developing devices is a cyan developing device in the second and a magenta developing device in the third.
5. The color image forming apparatus according to the present invention includes: Or 4. In the invention described in any one of the above, the toner on the outermost layer of the toner image having an L ^* value of 50 or more obtained by the fixing device is preferably a yellow toner.
6). The color image forming apparatus according to the present invention includes: Or 5. In the invention described in any one of the above, the image carrier that carries the electrostatic latent image and at least the developing device that is disposed to face the image carrier are integrally supported and detachable from the image forming apparatus main body. It is preferable to provide a simple process cartridge.

7). The color image forming method of the present invention includes a step of forming an electrostatic latent image corresponding to each color of yellow, cyan, magenta, and black on an image carrier, and an electrostatic latent image of each color on the image carrier. A developing process for developing the image by a developing device corresponding to each color toner, and a toner image on the image carrier is primarily transferred to an intermediate transfer member, and then the toner images on the intermediate transfer member are collectively transferred A color image forming method comprising: a transfer step of secondary transfer to a toner; and a fixing step of fixing a toner on the transfer body to form a toner image, wherein the L ^* value obtained by the fixing step is In the color image forming method, the start point of the decrease in the degree of methanol hydrophobicity of the toner forming the outermost layer of the toner image of 50 or more is 28 ≦ methanol / (methanol + water) (volume%). is there. (However, the lightness L ^* is a value of a fixed image in which the toner is uniformly adhered on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. )
8). In addition, the color image forming method of the present invention includes: In the invention described in item 1, it is preferable that the toner image having an L ^* value of 50 or more obtained by the fixing step contains at least yellow toner. (However, the lightness L ^* is a value of a fixed image in which toner is uniformly deposited on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. )
9. In addition, the color image forming method of the present invention includes: Or 8. In the invention described in (1), the developing devices for the respective colors used in the developing step are arranged in a tandem type, and the developing order in the developing step is such that the first is yellow and the fourth is black. preferable.
10. The color image forming method of the present invention is described in 9. In the invention described in (1), it is preferable that the second developing sequence is cyan and the third is magenta.
11. In addition, the color image forming method of the present invention includes: Or 10. In the invention described in any one of the above, it is preferable that the toner on the outermost layer of the toner image having an L ^* value of 50 or more obtained by the fixing step is a yellow toner.

  According to the color image forming apparatus and the color image forming method according to the present invention, when the lightness of the solid image after the output is a certain value or more, the affinity between the toner on the surface of the fixed image and the oil-based ink is improved. Therefore, it is possible to smoothly perform writing on the image.

Hereinafter, embodiments of the present invention will be described.
In the color image forming apparatus according to the present invention, when the L ^* value of the fixed solid image is 50 or more, the drop start point in the methanol hydrophobization degree of the toner forming the outermost layer of the solid image is 28 ≦ methanol / ( This is a color image forming apparatus characterized by being methanol + water) (volume%).
Here, the lightness L ^* indicates the degree of image brightness in a fixed image in which toner is uniformly adhered to the transfer target and the toner adhesion amount is 0.4 mg / cm ² or more. Value. The method for measuring the lightness L ^* will be described in detail in the following examples.

As a result of intensive investigations and examinations by the present inventors regarding the use form of the color output image, the lightness L ^* value of the solid image in which the toner adhesion amount is 0.4 mg / cm ² or more has a value of 50. In the case described above, it has been found that there are many demands from users for rewriting on the image using a writing instrument such as a ballpoint pen or a sign pen.
However, in the case of a solid image, if the affinity between the toner forming the surface of the image and the ink used for writing is low, the ink used for writing is repelled on the fixed image surface, and this The image cannot be smoothly added.
The fixed image formed by the color image forming apparatus according to the present invention is such that the degree of hydrophobicity of the toner that forms the outermost surface of the solid image that is highly likely to be subjected to the above-described writing is equal to or greater than a certain value. Since it is adjusted, the affinity between the toner on the surface of the solid image after fixing and the oil-based ink is improved, and writing with the oil-based ink on the solid image is performed smoothly.

In addition to oil-based inks, there are water-based inks as ink types used for writing, but solid images are close to a state in which a thin film is formed with a highly hydrophobic binder resin. It is substantially difficult to perform writing on this image using water-based ink.
For this reason, in general, oil-based ink having high affinity with a hydrophobic resin is used for writing on a solid image, but on the toner particle surface, the fluidity and chargeability of the toner are controlled. Therefore, inorganic fine particles or the like are externally added, and many of these inorganic fine particles contain a hydrophilic functional group such as a hydroxyl group. The surface composition of the toner is slightly different for each color toner of yellow, cyan, magenta, and black, and the characteristics of each color toner are also slightly different, but the toner that forms the surface of the fixed image is different from the oil-based ink. If the affinity is low, it becomes difficult to smoothly perform writing with oil-based ink on the fixed image.
The color image forming apparatus according to the present invention relates to a solid image having a lightness of a certain value or more, and by improving the hydrophobicity of the toner that forms the outermost surface, the affinity between the toner and the oil-based ink can be increased. This solid image can be surely and smoothly applied with oil-based ink.

  The lowering start point in the methanol hydrophobization degree of the toner indicates the high wettability as the toner, and the higher the value, the lower the level of wettability as the toner and the higher the hydrophobicity. It is shown that.

  The lowering start point in the methanol hydrophobization degree (methanol wettability) of the toner can be measured using a powder wettability tester (WET-100P, manufactured by Reska Co.). In a 100 ml beaker, 42 ml of pure water (ion-exchanged water or commercially available purified water) and 18 ml of methanol are put, covered and uniformly dispersed using an ultrasonic disperser. In a uniformly dispersed aqueous methanol solution, 0.5 g of toner is precisely weighed and added, stirred while stirring the stirrer at 250 rpm, and methanol is further added at 1.3 ml / min. When the toner begins to settle and disperse in the aqueous solution, the permeability of the solution decreases, and the ratio (%) of total methanol / (total methanol + water) at this time is set as the decrease start point of the toner hydrophobicity.

  If the hydrophobicity of methanol in the toner that forms the surface of the solid image is less than 28, the affinity between the toner that forms the outermost surface of the fixed image and the oil-based ink is insufficient, and the solid image after output In addition, when writing is performed using the oil-based ink, the oil-based ink is repelled on the surface of the fixed image, and it becomes difficult to perform writing on the image with the oil-based ink.

In the present embodiment, the toner having the above-described hydrophobicity is a yellow toner.
As a result of intensive investigations and examinations by the present inventors regarding the usage of color images, the lightness L ^* value of the solid image having a toner adhesion amount of 0.4 mg / cm ² is 50 or more. At one point, it was found that user requests for writing were high. Furthermore, the present inventors have measured the brightness of various color-fixed images and examined the results. As a result, a solid image having a brightness L ^* value of 50 or more is included in the toner layer forming this image. It became clear that yellow toner was included.
That is, in a solid image, a high request from the user is almost certainly formed by including a yellow toner in the toner layer. It is preferable to do.
As a result, the surface of a solid fixed image having a high demand for writing can be almost certainly made highly hydrophobic and easy to write with oil-based ink.

The color image forming apparatus according to this embodiment will be described in detail.
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. In FIG. 1, the copying apparatus main body 100 is provided with a paper feed table 200 on which the copying apparatus main body 100 is placed, a scanner 300 attached to the upper part of the copying apparatus main body 100, and an automatic document feeder (ADF) 400 attached to the upper part of the scanner 300. ing.
In the copying apparatus main body 100, a tandem is provided with four image forming units 16 provided in parallel around the photosensitive member 40 serving as a latent image carrier. The image forming units 16 each include various means for performing an electrophotographic process such as charging, developing, and cleaning. A type image forming apparatus 20 is installed. 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.
Further, below the intermediate transfer belt 10, a secondary transfer device 12 is disposed that batch-transfers the toner images superimposed on the intermediate transfer belt 10 onto transfer paper conveyed from the paper feed table 200. 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. In the vicinity of the secondary transfer device 12, a fixing device 25 for fixing the image on the transfer paper is provided. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt.
The secondary transfer device 12 described above also has a sheet conveyance function for conveying the transfer paper after image transfer to the fixing device 25. As the secondary transfer device 12, a transfer roller or a non-contact charger can be arranged. In this case, it is difficult to provide this sheet conveying function together.
In the illustrated example, a reversing device 28 for reversing the transfer paper for recording images on both sides of the transfer paper is provided below the secondary transfer device 12 and the fixing device 25 in parallel with the tandem image forming device 20 described above. Prepare.

  The developing device 4 of the image forming unit 16 uses the developer containing the toner. In the developing device 4, the developer carrying member carries and conveys the developer, and an alternating electric field is applied at a position facing the photoconductor 40 to develop 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 to set a document on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed. Hold 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 corresponding photoconductors 40 are rotated by the individual image forming units 16 to form monochrome images of black, yellow, magenta, and cyan 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 12, and transferred by the secondary transfer device 12. A color image is recorded on the sheet.

The image-transferred sheet is conveyed by the secondary transfer device 12 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 roller. 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 tandem type image forming apparatus 20 will be described in more detail with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of a tandem type image forming apparatus provided in the color image forming apparatus according to the present invention.
The tandem type image forming apparatus 20 includes an image forming unit 16a, an image forming unit 16b, an image forming unit 16c, and an image forming unit 16d arranged in parallel on the intermediate transfer belt 10 along the conveyance direction.
Each of the image forming units 16a to 16d includes a yellow developing device 4a, a cyan developing device 4b, a magenta developing device 4c, and a black developing device 4d.

  In this embodiment, the lowering start point in the methanol hydrophobicity of the yellow toner filled in the developing device 4a is adjusted to be 28 or more.

  The image forming units 16a to 16d have the same configuration. The configuration of the image forming unit 16a will be described as an example. The image forming unit 16a is provided with a photosensitive member 40a substantially at the center. A charging roller 3a is provided around the photoconductor 40a. Further, on the downstream side of the charging roller 18a, a developing device 4a, a blade cleaning device 7a, and a static elimination lamp (not shown) are provided.

  Further, the developing devices 4a to 4d provided in each image forming unit 16 can be a process cartridge that is integrally supported together with the photoconductors 40a to 40d and is detachably formed on the image forming apparatus main body. In addition, the process cartridge may include a charging unit and a cleaning unit.

  When the image forming operation by the tandem type image forming apparatus 20 is started, the yellow developing unit 4a, the cyan developing unit 4b, the magenta developing unit 4c, and the black developing unit 4d are used to place yellow on the photoreceptors 40a, 40b, 40c, and 40d. , Cyan, magenta, and black toner images Ta, Tb, Tc, and Td are formed, and the toner images Ta to Td are formed on the respective photoreceptors 40, on the intermediate transfer belt 10, and on the lower side, Ta, Tb, and Tc. , Td in this order to form a toner layer.

  As described above, the toner layer on the intermediate transfer belt 10 is moved to the position of the secondary transfer device 12 by the intermediate transfer belt 10 being rotated and conveyed by the support rollers 14 to 16, and the support roller. 16 and a support roller 23 that stretches the secondary transfer belt 24, and is secondarily transferred onto the transfer paper. At this time, the order of superimposing the toner layers on the paper is the reverse order of the superposition order on the intermediate transfer belt 10, and from the lower side, the order is Td, Tc, Tb, Ta.

The belt substrate of the intermediate transfer belt 10 may contain a small amount of water as the color image forming apparatus is used, but the toner transferred onto the intermediate transfer belt 10 is contained in the belt substrate. Contact with moisture contained in the toner, the chargeability of the toner is impaired, and when the toner is secondarily transferred onto the transfer paper P in the secondary transfer device 12, a cause of a large amount of transfer dust and toner scattering is generated. It becomes.
However, in the color image forming apparatus according to the present embodiment, the degree of hydrophobicity of the toner layer Ta of the yellow toner that is in contact with the intermediate transfer belt 10 is adjusted so as to be in the above range. Even if a small amount of water is contained in the belt base material, the toner charge amount is not lost due to the water, and transfer dust, toner scattering, etc. occur during the secondary transfer onto the transfer paper. Is prevented, and good image forming operation can be maintained.

As described above, the toner layer superimposed on the transfer paper surface in the order of Ta, Tb, Tc, and Td from the upper side is fixed on the paper surface by applying heat and pressure at the fixing nip N.
In the color image forming apparatus according to this embodiment, since the developing device 4a is filled with yellow toner, the surface of the fixed image containing yellow toner is always formed with yellow toner. Furthermore, since the hydrophobicity of the yellow toner is adjusted so as to satisfy the above-described range, the surface of the fixed image formed including the yellow toner can be surely brought into a highly hydrophobic state.
That is, since the surface of a solid image with high brightness can be in a state of high hydrophobicity and high affinity with oil-based ink, it is almost certain when additional writing is required on the solid image. In addition, it is possible to achieve a state in which writing with oil-based ink on the image can be performed smoothly.

Since the developing device 4d is filled with black toner, the black toner is transferred so as to form the lowermost layer on the paper surface.
When the black toner is superimposed on the paper surface so as to form the second or third layer from the outermost layer, the transparency of the toner image after fixing is greatly impaired, and the lower layer of the black toner layer is The expression of the color of the toner to be formed is hindered, and the color reproducibility and saturation are lowered.
The black toner is superimposed and transferred so as to be the lowermost layer on the paper surface, whereby the color reproducibility and saturation of the obtained fixed image can be improved.

Also, the developing device 4b is filled with cyan toner and the developing device 4c is filled with magenta toner, so that on the paper surface, the second layer from the outermost layer is formed with cyan toner, and the third layer is magenta toner. It is formed by. As a result, it is possible to obtain a good color image with good color reproducibility and high saturation.
Note that the arrangement order of the developing devices is not limited to the above-described order, and color image formation can be performed in another arrangement order.

The fixing device used in the image forming apparatus of the present invention will be described below.
As the fixing device, a known device can be used. For example, an electromagnetic induction that generates Joule heat by an eddy current generated in a magnetic metal member by an alternating magnetic field and causes a heating body including the metal member to generate electromagnetic induction heat. A heating type fixing device can be preferably used.
Hereinafter, the fixing device 25 will be described in detail. FIG. 3 is an enlarged view of the fixing device according to the present invention.
In FIG. 3, the fixing device 25 is stretched between a heating roller 251 heated by electromagnetic induction of the induction heating unit 256, a fixing roller 252 arranged in parallel to the heating roller 251, and the heating roller 251 and the fixing roller 252. An endless belt-like heat-resistant belt (toner heating medium) 253 that is heated by the heating roller 251 and rotated in the direction of arrow A by at least one of these rollers rotating, and press-contacted to the fixing roller 252 via the belt 253 And a pressure roller 254 that rotates in the forward direction with respect to the belt 253.

The heating roller 251 is made of, for example, a hollow cylindrical magnetic metal member such as iron, cobalt, nickel, or an alloy of these metals, and has an outer diameter of 20 mm and a wall thickness of, for example, 0.1 mm. It has a fast configuration.
The fixing roller 252 includes a metal core 252a made of, for example, stainless steel, and an elastic member 252b covered with a core metal 252a in a solid or foamed heat-resistant silicone rubber. In order to form a contact portion having a predetermined width between the pressure roller 254 and the fixing roller 252 by the pressing force from the pressure roller 254, the outer diameter is set to about 40 mm, which is larger than the heating roller 251. The elastic member 252b has a thickness of about 3 to 6 mm and a hardness of about 40 to 60 ° (Asker hardness).
With this configuration, since the heat capacity of the heating roller 251 is smaller than the heat capacity of the fixing roller 252, the heating roller 251 is rapidly heated and the warm-up time is shortened.

The belt 253 stretched between the heating roller 251 and the fixing roller 252 is heated at a contact portion W1 with the heating roller 251 heated by the induction heating unit 256. The inner surface of the belt 253 is continuously heated by the rotation of the heating roller 251 and the fixing roller 252, and as a result, the entire belt is heated.
The belt 253 is provided with a release layer on a heat generating layer made of metal. The thickness of the release layer is preferably about 50 μm to 500 μm, particularly about 200 μm. By doing so, the toner image T formed on the recording material P is sufficiently wrapped by the surface layer portion of the belt 253, so that the toner image T can be uniformly heated and melted.
When the thickness of the release layer is less than 50 μm, the heat capacity of the belt 253 becomes small, and the belt surface temperature rapidly decreases in the toner fixing process, so that sufficient fixing performance cannot be ensured. Further, when the thickness of the release layer is larger than 500 μm, the heat capacity of the belt 253 increases and the time required for warm-up becomes longer. In addition, in the toner fixing process, the belt surface temperature is difficult to decrease, the agglomeration effect of the melted toner at the fixing portion outlet cannot be obtained, the belt releasability is reduced, and the toner adheres to the belt. Hot offset occurs. As a base material for the belt 253, a heat-resistant resin layer such as a fluorine resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, or a PPS resin is used instead of the heat generating layer made of the metal. It may be used.

The pressure roller 254 includes a cored bar 254a made of a metal member having a high thermal conductivity, such as copper or aluminum, and an elastic member having a high heat resistance and a high toner releasability provided on the surface of the cored bar 254a. 254b. In addition to the above metal, SUS may be used for the core metal 254a.
The pressure roller 254 presses the fixing roller 252 via the belt 253 to form the fixing nip portion N. In this embodiment, the pressure roller 254 is harder than the fixing roller 252. As a result, the pressure roller 254 bites into the fixing roller 252 (and the belt 253), and the recording material P follows the circumferential shape of the surface of the pressure roller 254 due to this biting. Has the effect of facilitating. The outer diameter of the pressure roller 254 is about 40 mm, which is the same as that of the fixing roller 252, but the wall pressure is about 1 to 3 mm, thinner than the fixing roller 252, and the hardness is about 50 to 70 ° (Asker hardness) as described above. The fixing roller 252 is harder.

As shown in FIG. 3 and FIGS. 4A and 4B, the induction heating means 256 that heats the heating roller 251 by electromagnetic induction includes an excitation coil 257 that is a magnetic field generation means, and the excitation coil 257 is wound. The coil guide plate 258 is provided. The coil guide plate 258 has a semi-cylindrical shape arranged close to the outer peripheral surface of the heating roller 251. As shown in FIG. 4B, the excitation coil 257 is formed of a single long excitation coil wire. It is alternately wound along the axial direction of the heating roller 251 along the line 268.
The exciting coil 257 is connected to a drive power source (not shown) whose oscillation circuit has a variable frequency.

  Outside the excitation coil 257, a semi-cylindrical excitation coil core 259 made of a ferromagnetic material such as ferrite is fixed to the excitation coil core support member 260 and is disposed close to the excitation coil 257. In the present embodiment, the exciting coil core 259 having a relative permeability of 2500 is used.

The excitation coil 257 is supplied with a high frequency alternating current of 10 kHz to 1 MHz, preferably a high frequency alternating current of 20 kHz to 800 kHz from the drive power source, thereby generating an alternating magnetic field. The alternating magnetic field acts on the heat generation layer of the heating roller 251 and the belt 253 in the contact area W1 between the heating roller 251 and the heat-resistant belt 253 and the vicinity thereof, and in the direction in which the change of the alternating magnetic field is prevented. Eddy current flows.
This eddy current generates Joule heat corresponding to the resistance of the heat generating layer of the heating roller 251 and the belt 253, and the belt having the heating roller 251 and the heat generating layer mainly in the contact area between the heating roller 251 and the belt 253 and in the vicinity thereof. 253 is heated by electromagnetic induction.
The belt 253 heated in this way is in the vicinity of the inlet side of the fixing nip portion N, and a temperature detecting means 255 comprising a thermosensitive element such as a thermistor disposed in contact with the inner surface side of the belt 253. Thus, the belt inner surface temperature is detected.

  By the fixing device 25 described above, the heating roller 251 and the belt 253 can be heated instantaneously, and the warm-up time of the device can be shortened. Further, the temperature detecting means 255 provided in the vicinity of the entrance of the fixing nip portion N detects the temperature change of the fixing nip portion N in a timely manner, and when a temperature drop is detected, the heating roller 251 instantaneously moves to the belt 253. Since the heating is performed, the toner image T on the recording material P can be fixed satisfactorily without causing a cold offset. Further, the developer used in the developing device 4 is excellent in low-temperature fixability, which will be described later, and includes an electrostatic charge image developing toner having a sufficient fixing temperature range, so that an image with better fixability can be output. Can do.

The electromagnetic induction heating type fixing device as described above is not limited to the configuration shown in FIG. 3, and for example, a film heating method as shown in FIG. 5 may be used.
FIG. 5 is a schematic view showing another embodiment of a fixing device using an electromagnetic induction heating method.
The fixing device 70 shown in FIG. 5 has a film inner surface guide 702 on which a heating body 701 including an exciting coil unit 701a and a magnetic metal member 701b as a heating unit is mounted, and the magnetic metal member 701b in contact with an inner wall. A fixing nip portion N is formed between the heat-resistant cylindrical film 703 wrapping the film inner surface guide 702 and the film 703 at the position of the magnetic metal member 701b, and the film 703 is attached. The pressure roller 704 is rotated.
The film 703 has a film thickness of 100 μm or less, preferably 50 μm or less, and a single layer film such as PTFE, PFA, FEP, etc. having heat resistance, or an outer peripheral surface of a film such as polyimide, polyamideimide, PEEK, PES, PPS A composite layer film coated with PTFE, PFA, FEP or the like is used.
The film inner surface guide 702 is made of a member having rigidity and heat resistance formed of a resin such as PEEK or PPS, and the heating body 701 is fitted in a substantially central portion of the film inner surface guide 702 in the longitudinal direction. .
The pressure roller 704 includes a core 704a and a heat-resistant rubber layer 704b having good releasability such as silicone rubber provided around the core 704a, and a predetermined pressing force is applied by a bearing or an urging means (none of which is shown). Holding the film 703, the magnetic metal member 701b of the heating body 701 is disposed in pressure contact with the film 703. The pressure roller 704 is rotated counterclockwise by a driving means (not shown).
By the rotational driving of the pressure roller 704, a frictional force is generated between the pressure roller 704 and the film 703, and the rotational force acts on the film 703. The film 703 is in close contact with the magnetic metal member 701b of the heating body 701. Slide and rotate.
Recording with an unfixed toner image T formed by an image forming unit (not shown) between the film 703 and the pressure roller 704 in the fixing nip N in a state where the heating body 701 has reached a predetermined temperature. The material P is introduced. The recording material P is sandwiched between the pressure roller 704 and the film 703 and conveyed through the fixing nip N, whereby the heat of the magnetic metal member 701b is applied to the recording material P via the film 703, and the unfixed toner image T Is melt-fixed on the recording material P. At the exit of the fixing nip portion N, the recording material P that has passed is separated from the surface of the film 703 and conveyed to a paper discharge tray (not shown).
As described above, in the electromagnetic induction heating type fixing device, the magnetic metal member 701b as the induction heating means is disposed close to the toner image T of the recording material P through the film 703 by utilizing the generation of eddy current. Therefore, the heating efficiency is further improved as compared with the fixing device of the film heating type.

In addition to the above-described electromagnetic induction heating type fixing device, for example, a heat roller type fixing device can also be used as the fixing device provided in the color image forming apparatus according to the present invention.
FIG. 6 is a diagram showing another embodiment of the fixing device provided in the color image forming apparatus according to the present invention.
A fixing device 80 shown in FIG. 6 is a heat roller type fixing device. As a basic configuration, a fixing roller 821 having a heating device 824 (hereinafter referred to as “heater”) such as a halogen lamp, and foaming on a core metal 826. A pressure roller 825 having an elastic layer 827 such as silicone rubber and being pressed against the fixing roller 821 is provided. A release layer 828 made of a PFA tube or the like is provided on the elastic layer 827 of the pressure roller 825. The fixing roller 821 is provided with an elastic layer 822 such as silicone rubber on a core metal 830, and a resin surface layer 823 having good releasability such as fluororesin is formed for the purpose of preventing adhesion due to toner viscosity. . The thickness of the elastic layer 822 is usually preferably about 100 to 500 μm in consideration of image quality and heat transfer efficiency during fixing. The resin surface layer 823 is composed of a PFA tube or the like, similarly to the pressure roller 825, and its thickness is preferably about 10 to 50 μm in consideration of mechanical deterioration. A temperature detector 829 is provided on the outer peripheral surface of the fixing roller 821, and the heater 824 is controlled so as to keep the temperature substantially constant by detecting the surface temperature of the fixing roller 821.

In the fixing device having such a configuration, the fixing roller 821 and the pressure roller 825 are brought into pressure contact with each other with a predetermined pressure to form the fixing nip portion N, and are each driven by a driving means (not shown) to receive an arrow. By rotating in the R21 direction and the arrow R25 direction, the transfer material P is nipped and conveyed at the fixing nip portion N described above. At this time, the fixing roller 821 is controlled to a predetermined temperature by the heater 824, and the toner image T on the transfer paper P is thermally melted under pressure when passing between the two rollers, and exits the roller pair. By being cooled, it is fixed on the transfer paper P as a permanent image.
The pressure roller 825 has an outer diameter of 30 mm, a wall thickness of 6 mm, a surface covered with a conductive PFA tube, and an on-axis rubber hardness of 42 HS (Asuka C). The fixing roller 821 is made of an aluminum core and has a thickness of 0.4 mm. In this configuration, in order to obtain the nip N, pressure is applied to both ends of the roller, and the surface pressure at that time is 8.3 N / cm ² .

In the heat roller type fixing device as described above, the toner on the fixing roller 821 shifts to the pressure roller 825 due to the use over time, and the toner is transferred to cause stain on the back surface of the recording paper. To do.
The fixing device 80 of the present invention includes a fixing cleaning roller 831 so as to contact the surface of the pressure roller 825 in order to remove such residual toner on the pressure roller 825.
Thereby, a small amount of toner adhering to the pressure roller 825 is removed, and contamination on the back surface of the transfer paper can be prevented.

Note that the temperature of the surface of the fixing roller 821 is preferably controlled to be within an appropriate fixing temperature range by the temperature detection unit 829.
As described above, when the fixing device 80 including the fixing cleaning roller 831 is used at a high temperature, the toner accumulated on the fixing cleaning roller 831 is melted by heat and is reversely transferred to the pressure roller 825, so-called reverse hot offset. Will occur.
Since the toner of the present invention has improved low-temperature fixability, even when the surface temperature of the fixing roller 821 is used within the above range, a good image can be stably provided without causing fixing failure. Can do.

In the toner according to the present invention, the base particles are produced by the following raw materials and production methods, for example.
(Modified polyester)
The toner according to the present invention contains a modified polyester (i) as a binder resin. The modified polyester (i) refers to a state in which a bonding group other than an ester bond is present in the polyester resin, or resin components having different configurations are bonded to the polyester resin by a covalent bond, an ionic bond, or the like. Specifically, the polyester terminal is modified by introducing a functional group such as a carboxylic acid group or an isocyanate group that reacts with a hydroxyl group into the polyester terminal and further reacting with an active hydrogen-containing compound.

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

The urea-modified polyester is produced as follows.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). Dihydric alcohol (DIO) alone or (DIO) and a small amount of (TO) Is preferred. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. As trihydric or higher polyhydric alcohol (TO), 3 to 8 or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

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

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

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

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

The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of B1 to B5 blocked amino groups (B6) include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.
The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

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

(Unmodified polyester)
In the present invention, not only the modified polyester (i) is used alone, but also the unmodified polyester (ii) can be contained as a binder resin component together with the (i). By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color device are improved, which is preferable to the single use. Examples of (ii) include polycondensates of a polyhydric alcohol (PO) and a polyvalent carboxylic acid (PC), which are the same as the polyester component (i), and preferred ones are also the same as (i). . Further, (ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, for example, may be modified with a urethane bond. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, the polyester component (i) and (ii) preferably have similar compositions. In the case of containing (ii), the weight ratio of (i) to (ii) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75, Particularly preferred is 7/93 to 20/80. When the weight ratio of (i) is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The peak molecular weight of (ii) is 1000-10000 normally, Preferably it is 2000-8000, More preferably, it is 2000-5000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. As for the acid value of (ii), 1-5 are preferable, More preferably, it is 2-4. Since a high acid value wax is used for the wax, a low acid value of the binder resin component leads to chargeability and high volume resistance, so it is easy to match a toner used for a two-component developer.

  The glass transition point (Tg) of the binder resin is usually 35 to 70 ° C., preferably 55 to 65 ° C. If the temperature is lower than 35 ° C., the heat-resistant storage stability of the toner deteriorates, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the toner of the present invention tends to have good heat storage stability even when the glass transition point is low, as compared with known polyester-based toners. Show.

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

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

(Release agent)
As the release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface, thereby fixing. Effective against high temperature offset without applying a release agent such as oil to the roller. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The release agent can be melt-kneaded together with the master batch and the binder resin, and of course, it may be added when dissolved and dispersed in the organic solvent.

Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.
(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.

Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

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

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

As the resin fine particles, any resin can be used as long as it can form an aqueous dispersion, and it may be a thermoplastic resin or a thermosetting resin. Examples thereof include vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin, two or more of the above resins may be used in combination.
Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained. For example, vinyl resins are polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid-acrylic acid esters. Examples thereof include resins such as a polymer, a styrene-acrylonitrile copolymer, a styrene-maleic anhydride copolymer, and a styrene- (meth) acrylic acid copolymer. The average particle size of the resin fine particles is 5 to 200 nm, preferably 20 to 300 nm.
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

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

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

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

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

Further, the obtained toner particles can be classified as necessary to adjust the particle size distribution to a desired level. In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder as a powder after drying. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, fine particles or coarse particles may be wet.
It is preferable to remove the used dispersant from the obtained emulsified dispersion as much as possible, but it is preferable to carry out it simultaneously with the above classification operation.

Further, the obtained toner may be subjected to a charge control agent driving and an external additive dry treatment as necessary. The injection of the charge control agent and the dry treatment of the external additive are performed by a known method using a mixer or the like.
Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) has been modified to reduce the pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron System (manufactured by Kawasaki Heavy Industries Ltd.), automatic mortar, etc.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.
The amount of charge control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not limited uniquely. However, it is preferably used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is lowered, and the image density is lowered. Invite.

(External additive)
As the external additive for assisting the fluidity, developability and chargeability of the toner, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 nm to 2 μm, and particularly preferably 5 nm to 500 nm. 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.
Other polymer fine particles such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine and nylon, and thermosetting resin Examples include polymer particles.
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 a fluoroalkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .

The toner for image formation of the present invention has a volume average particle diameter (Dv) of 3.0 to 8.0 μm, and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn). Is preferably 1.00 to 1.40. By using a toner having such a particle size and particle size distribution, it has excellent heat-resistant storage stability, low-temperature fixability, and hot offset resistance, and particularly excellent gloss when used in a full-color copying machine. Sex is obtained.
In general, it is said that the smaller the particle size of the toner, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning properties. is there. In addition, when the volume average particle size is smaller than the range of the present invention, in the case of a two-component developer, the toner is fused to the surface of the magnetic carrier during a long period of stirring in the developing device, and the charging ability of the magnetic carrier is reduced. When used as a developer, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur.
On the contrary, when the volume average particle diameter of the toner is larger than the range of the present invention, it becomes difficult to obtain a high-resolution and high-quality image, and when the balance of the toner in the developer is performed. In many cases, the variation in the particle size of the toner becomes large.
On the other hand, if Dv / Dn exceeds 1.40, the charge amount distribution becomes wide and the resolving power decreases, which is not preferable.

The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter, Inc.) as a measuring device.
The measuring method is as follows. First, 0.1 to 5 ml of a surfactant (preferably alkyl benzene sulfonate) is added as a dispersant to 100 to 150 ml of an electrolytic aqueous solution. Here, the electrolytic solution was prepared by preparing approximately 1% NaCl aqueous solution using primary sodium chloride, and ISOTON R-II (manufactured by Coulter Scientific Japan) was used. Further, 2 to 20 mg of a measurement sample was added thereto, suspended in an electrolytic solution, and subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. Using the measurement apparatus, the volume and number of toner particles in the sample were measured for each channel using a 100 μm aperture as the aperture, and the volume distribution and number distribution of the toner were calculated.
In addition, as a channel, it is 2.00-2.52 micrometer; 2.52-3.17 micrometer; 3.17-4.00 micrometer; 4.00-5.04 micrometer; 5.04-6.35 micrometer; 6.35- 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32. 00 μm; 13 channels from 32.00 to 40.30 μm were used.

The image forming toner of the present invention is preferably a toner having a shape factor SF-1 in the range of 100 to 180 and SF-2 in the range of 100 to 180. FIG. 7 is a diagram schematically showing the shape of the toner for explaining the shape factor SF-1 and FIG. 8 is for explaining the shape factor SF-2.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape. The square of the maximum length MXLNG of the shape formed by projecting the toner onto the two-dimensional plane represented by the following formula (1) Divide by AREA and multiply by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
The shape factor SF-2 indicates the ratio of unevenness in the shape of the toner, and is expressed by the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane represented by the following formula (2). It is a value obtained by dividing the figure area AREA and multiplying by 100 / 4π.
^{SF-2 = {(PERI)} 2 / AREA} × (100 / 4π) ··· Equation (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

When the shape factors SF-1 and SF-2 are both close to 100 and the shape of the toner is close to a true sphere, the contact between the toner and the toner or the toner and the image carrier becomes a point contact. As a result, the fluidity becomes weaker, the fluidity becomes higher, and the adhesion between the toner and the image carrier becomes weaker, and the transfer rate becomes higher. The dot reproducibility is also improved. On the other hand, when the toner shape factors SF-1 and SF-2 are large to some extent, the margin for cleaning increases, and there is no problem such as defective cleaning. Therefore, it is preferable that the shape factors SF-1 and SF-2 are in the range of 100 to 180 as a range in which the image quality is not deteriorated from the balance between the two.
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 is a value obtained by performing an analysis by introducing into the formula (1) and calculating from the formula (1).
The shape factor SF-2 is obtained by randomly sampling 50 toner particle images magnified to a magnification of 3500 times using an electron microscope, introducing the image information into an image analysis apparatus via an interface, and performing analysis. It is a value obtained from 2).

  When the shape factors SF-1 and SF-2 are both close to 100 and the shape of the toner is close to a true sphere, the contact between the toner and the toner or the toner and the image carrier becomes a point contact. Accordingly, the fluidity is increased and the adhesion between the toner and the image carrier is also weakened, and the transfer rate is increased. The dot reproducibility is also improved. On the other hand, when the toner shape factors SF-1 and SF-2 are large to some extent, the margin for cleaning increases, and there is no problem such as defective cleaning. Therefore, it is preferable that the shape factors SF-1 and SF-2 are in the range of 100 to 180 as a range in which the image quality is not deteriorated from the balance between the two.

Further, the image forming toner of the present invention can be expressed by the following shape rule.
FIG. 9 is a diagram schematically showing the shape of the toner according to the present invention. In FIG. 9, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner of the present invention has a major axis and a minor axis. Ratio (r2 / r1) (see FIG. 9B) is 0.5 to 1.0, and the ratio of thickness to minor axis (r3 / r2) (see FIG. 9C) is 0.7 to 1.0. It is preferable to be in the range of 1.0. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved.
Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

  The toner for image formation of the present invention can be used as a magnetic toner containing a magnetic substance. Examples of the magnetic material contained in the toner include iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel. Alternatively, alloys of these metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof are included. . Magnetite is particularly preferable from the viewpoint of magnetic properties. These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm. The amount of the ferromagnetic material to be contained in the toner is about 15 to 200 parts by weight, particularly preferably 100 parts by weight of the resin component, with respect to 100 parts by weight of the resin component. 20 to 100 parts by weight per part.

  The image forming toner of the present invention can be used as a one-component developer or a two-component developer combined with a magnetic carrier. As the magnetic carrier when the toner of the present invention is used as a two-component developer, all known carriers can be used, for example, magnetic powder such as iron powder, ferrite powder, nickel powder, glass beads, and the like. Those whose surfaces are treated with a resin or the like. Examples of the resin powder that can be coated on the magnetic carrier in the present invention include a styrene-acrylic copolymer, a silicone resin, a maleic acid resin, a fluorine resin, a polyester resin, and an epoxy resin. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, when the styrene content is less than 30% by weight, the development characteristics are low, and when it exceeds 90% by weight, the coating film becomes hard and easily peeled, and the life of the carrier is shortened. Moreover, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive material, a charge control agent and the like in addition to the resin.

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

(Manufacture of toner)
<Production Example 1>
~ Example of production of inorganic fine particles ~
Blowing liquid SiCl ₄ ingredients core at a flow rate of Ar gas as a carrier gas using a liquid material supply system 300 SCCM (min standard volume flow (CC)), the SiCl ₄ vapor flow rate 250 SCCM, _{H 2} gas 20 SLM (per Minute standard volume flow rate (L)) and O ₂ gas 20SLM were sent to a core burner for flame hydrolysis and fusion to produce SiO ₂ fine particles. The fine particles were grown to a predetermined primary particle size, and the obtained fine particles were subjected to a hydrophobizing treatment with hexamethyldisilazane to obtain [Inorganic fine particles 1] having an average primary particle size of 5 nm.

<Production Example 2>
~ Synthesis of organic fine particle emulsion ~
In a reaction vessel equipped with a stir bar and a thermometer, 683 parts of water, 11 parts of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries), 80 parts of styrene, 83 parts of methacrylic acid, When 110 parts of butyl acrylate, 12 parts of butyl thioglycolate and 1 part of ammonium persulfate were added and stirred for 15 minutes at 400 rpm, a white emulsion was obtained. The system was heated to raise the system temperature to 75 ° C. and reacted for 5 hours. Further, 30 parts of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours, and an aqueous vinyl resin (a copolymer of styrene-methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt). A dispersion was obtained. This is designated as [fine particle dispersion 1]. The volume average particle size of the [fine particle dispersion 1] measured by a laser diffraction particle size distribution analyzer (LA-920, manufactured by Shimadzu Corp.) was 120 nm. A portion of [Fine Particle Dispersion 1] was dried to isolate the resin component. The Tg of the resin was 42 ° C., and the weight average molecular weight was 30,000.

<Production Example 3>
~ Preparation of aqueous phase ~
990 parts of water, 65 parts of [fine particle dispersion 1], 37 parts of a 48.5% aqueous solution of sodium dodecyl diphenyl ether disulfonate (ELEMINOL MON-7 manufactured by Sanyo Chemical Industries) and 90 parts of ethyl acetate were mixed and stirred to give a milky white color Obtained liquid. This is designated as [Aqueous Phase 1].

<Production Example 4>
~ Synthesis of low molecular weight polyester ~
In a reaction vessel equipped with a condenser, stirrer and nitrogen inlet tube, 229 parts of bisphenol A ethylene oxide 2-mole adduct, 529 parts of bisphenol A propylene oxide 3-mole adduct, 208 parts terephthalic acid, 46 parts adipic acid and dibutyl Add 2 parts of tin oxide, react for 8 hours at 230 ° C. under normal pressure, and further react for 5 hours under reduced pressure of 10 to 15 mmHg. The mixture was reacted for 2 hours to obtain [Low molecular polyester 1]. [Low molecular polyester 1] had a number average molecular weight of 2500, a weight average molecular weight of 6700, a Tg of 43 ° C., and an acid value of 25.

<Production Example 5>
~ Synthesis of intermediate polyester ~
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 682 parts of bisphenol A ethylene oxide 2-mole adduct, 81 parts of bisphenol A propylene oxide 2-mole adduct, 283 parts of terephthalic acid, trimellitic anhydride 22 And 2 parts of dibutyltin oxide were added, reacted at 230 ° C. for 8 hours at normal pressure, and further reacted for 5 hours at a reduced pressure of 10 to 15 mmHg to obtain [Intermediate Polyester 1]. [Intermediate Polyester 1] had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, Tg of 55 ° C., an acid value of 0.5, and a hydroxyl value of 51.

<Production Example 6>
-Synthesis of a modified polyester resin (referred to as prepolymer 1) capable of reacting with a compound having at least an active hydrogen group-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 410 parts of the above [intermediate polyester 1], 125 parts of isophorone diisocyanate, and 500 parts of ethyl acetate were added and reacted at 100 ° C. for 5 hours. ] Was obtained. The average number of isocyanate groups contained per molecule of [Prepolymer 1] was 2.15.

<Production Example 7>
~ Synthesis of ketimine ~
In a reaction vessel equipped with a stir bar and a thermometer, 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to obtain [ketimine compound 1]. The amine value of [ketimine compound 1] was 418.

<Production Example 8>
~ Master batch synthesis ~
(black)
1200 parts of water, 60 parts of carbon black (manufactured by Cabot, Regal 400R), 40 parts of polyester resin (manufactured by Sanyo Kasei, RS801), and further 30 parts of water are added and mixed with a Henschel mixer (manufactured by Mitsui Mining). The mixture was kneaded at 150 ° C. for 30 minutes using two rolls, rolled and cooled, and pulverized with a pulverizer to obtain [Masterbatch 1].
(cyan)
1200 parts of water, 50 parts of copper phthalocyanine pigment (PB15: 3), 50 parts of polyester resin (manufactured by Sanyo Kasei, RS801), and further 30 parts of water are added and mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). After kneading at 150 ° C. for 30 minutes using two rolls, rolling and cooling and pulverizing with a pulverizer, [Masterbatch 1] was obtained.
(Magenta)
Add 1200 parts of water, 50 parts of naphthol pigment (PR269), 50 parts of polyester resin (manufactured by Sanyo Kasei, RS801), 30 parts of water, and mix with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). After kneading at 150 ° C. for 30 minutes using a roll, the product was cooled by rolling and pulverized with a pulverizer to obtain [Masterbatch 1].
(yellow)
Add 1200 parts of water, 50 parts of disazo pigment (PY155), 50 parts of polyester resin (manufactured by Sanyo Kasei, RS801), 30 parts of water, and mix with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). After kneading at 150 ° C. for 30 minutes using a roll, the product was cooled by rolling and pulverized with a pulverizer to obtain [Masterbatch 1].

<Production Example 9>
-Production of toner composition containing oil phase, that is, inorganic fine particles-
In a container equipped with a stir bar and a thermometer, 400 parts of [Low molecular weight polyester 1], 110 parts of carnauba wax and 947 parts of ethyl acetate were charged, heated to 80 ° C. with stirring, and maintained at 80 ° C. for 5 hours. Thereafter, it was cooled to 30 ° C. at 1 hour.
Next, yellow, cyan, magenta, or black [Masterbatch 1] was added to the container, and 500 parts of ethyl acetate was charged and mixed for 1 hour to obtain [Raw Material Solution 1].
The amount of [Masterbatch 1] added to the container is 500 parts for a black masterbatch, 400 parts for a cyan masterbatch, 450 parts for a magenta masterbatch, and a yellow masterbatch. Was 550 parts.
[Raw material solution 1] 1324 parts are transferred to a container, and using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.), a liquid feed speed of 1 kg / hr, a disk peripheral speed of 6 m / sec, and 0.5 mm zirconia beads are 80% by volume. The wax was dispersed under the conditions of filling and 3 passes. Next, 1324 parts of a 65% ethyl acetate solution of [low molecular weight polyester 1] and 34 parts of the above [inorganic fine particles 1] were added, followed by one pass with a bead mill under the above conditions to obtain [Pigment / Wax Dispersion 1]. The solid content concentration of [Pigment / Wax Dispersion 1] (130 ° C., 30 minutes) was 50%.

<Production Example 10>
~ Emulsification ~
[Pigment / Wax Dispersion 1] 648 parts, [Prepolymer 1] 154 parts, [Ketimine Compound 1] 8.5 parts in a container, TK homomixer (manufactured by Tokushu Kika) at 5,000 rpm for 1 minute After mixing, 1200 parts of [Aqueous Phase 1] was added to the container and mixed with a TK homomixer at a rotation speed of 10,000 rpm for 20 minutes to obtain [Emulsion Slurry 1].
That is, it is dispersed in an aqueous medium containing resin fine particles and an elongation reaction is performed.

<Production Example 11>
~ Solvent removal ~
[Emulsion slurry 1] was put into a container equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging was carried out at 45 ° C. for 4 hours to obtain [Dispersion slurry 1].

<Production Example 12>
~ Washing and drying ~
[Dispersion Slurry 1] After filtering 100 parts under reduced pressure,
(1): 100 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.
(2): 1O parts of 10% sodium hydroxide aqueous solution was added to the filter cake of (1), mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure.
(3): 100 parts of 10% hydrochloric acid was added to the filter cake of (2), mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
(4): 300 parts of ion-exchanged water was added to the filter cake of (3), mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered twice to obtain a cake-like product. . This is designated as [Filter cake 1].
[Filter cake 1] was dried at 45 ° C. for 48 hours in a circulating dryer. Thereafter, the mixture was sieved with a 75 μm mesh to obtain toner base particles. This is designated as [toner base particle 1].

<Production Example 13>
~ External additive treatment ~
To 100 parts of [Toner Base Particle 1] obtained above, 2.0 parts of hydrophobic silica as an external additive and 0.75 part of hydrophobic titanium oxide were mixed with a Henschel mixer, and [Toner 1 ] Was obtained.

<Production Example 14>
-Manufacture of carriers-
・ Core material Mn ferrite particles (weight average diameter: 35 μm) ・ ・ ・ 5000 parts ・ Coating material toluene ・ ・ ・ 450 parts Silicone resin SR2400
(Toray Dow Corning Silicone, 50% non-volatile) 450 parts aminosilane SH6020
(Toray Dow Corning made of 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 this coating solution and core material are placed in a fluidized bed. The coating liquid was applied to the core material by applying the coating liquid while coating while forming a swirling flow provided with a rotating bottom plate disk and a stirring blade. The obtained coated product was baked in an electric furnace at 250 ° C. for 2 hours to obtain the above [Carrier 1].

<Production Example 15>
-Adjustment of developer-
7% by weight of [Toner 1] and 93% by weight of [Carrier 1] were uniformly mixed and charged using a type of tumbler mixer in which the container was rolled and stirred to prepare a developer.

Example 1
[Toner 1] and [Carrier 1] corresponding to each color of yellow (Y), cyan (C), magenta (M), and black (K) obtained by the above production example are produced by the method shown in Production Example 14. Each color developer was prepared by mixing.
Using these developers, the color image forming apparatus shown in FIG. 1 is used to superimpose a single color image of yellow, magenta, and cyan, and two colors of green (Y + C), red (Y + M), and blue (M + C). A color image obtained by the combination was formed.
At this time, the arrangement order of the color developing devices in the tandem type image forming apparatus 20 is set in the order of Y⇒C⇒M.
The obtained color image was subjected to image evaluation using the method described in detail below.
The evaluation results are shown in Table 2.

(Comparative Example 1)
In Example 1, a color image is formed in the same manner as in Example 1 except that the arrangement order of the color developing devices in the tandem type image forming apparatus 20 is M⇒C⇒Y. went.
The developer was prepared in the same manner as in Example 1, using [Toner 1] and [Carrier 1] corresponding to each color, prepared as in the above production example, as in Example 1. did.
The evaluation results are shown in Table 2.

(Comparative Example 2)
In Example 1, each color toner was prepared in the same manner as in Example 1 except that the hydrophobic silica used in Production Example 13 was silica that had not been subjected to a hydrophobization treatment. ] Was used to prepare each color developer.
Thereafter, a color image was formed in the same manner as in Example 1, and this image was evaluated.
Note that the order of development in the tandem type image forming apparatus 20 is the order of Y⇒C⇒M, as in the first embodiment.
The evaluation results are shown in Table 2.

[Evaluation methods]
(Evaluation item)
(1) Ease of writing with an oil-based ballpoint pen A solid image is output using an evaluation machine that has been tuned by modifying the Ricoh IPSiO Color 8100 to an oil-less fixing system, and writing on this solid image with an oil-based ballpoint pen Do. The level where the written characters are the same as when written on white paper is ◎, slightly thinner than when written on white paper, but the level where there is no problem in practicality, ○ the characters are faint Levels that are difficult to read are indicated by Δ, and levels that cannot be written at all are indicated by ×.
(2) Lightness L ^*
Using the fixing device shown in FIG. 3, a plain image and a thick paper transfer paper (Ricoh Type 6200 and NBS Ricoh Copied Printing Paper <135>) are solid images of 0.4 ± 0.02 mg / cm ² . Adjustment was made so that the toner was developed, and adjustment was made so that the temperature of the fixing belt was 160 ° C., and the toner image was fixed. L ^* of the image after fixing was measured using a 938 spectrodensitometer (manufactured by X-Rite).
(3) Start of descent in methanol hydrophobization degree Using a powder wettability tester (WET-100P, manufactured by RHESCA), methanol is added under the conditions of 1 ml / min with respect to 50 ml of pure water. The descent start point at this time was measured.

  The physical properties of the obtained toner are shown in Table 1, and the evaluation results are shown in Table 2.

From the results of Table 2, the surface of the fixed solid image having a lightness of 50 or more obtained by the color image forming apparatus according to the first embodiment of the present invention is in a state of good affinity with the oil-based ink. Therefore, writing using oil-based ink can be performed smoothly.
On the other hand, the fixed solid image surface obtained by the color image forming apparatus according to Comparative Examples 1 and 2 has poor affinity with the oil-based ink, and writing on the image with the oil-based ink cannot be performed smoothly. As a result, it was difficult to distinguish written characters.

1 is a schematic configuration diagram of a color image forming apparatus according to the present invention. 1 is a diagram illustrating a schematic configuration of a tandem type image forming apparatus provided in a color image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing a fixing device according to the present invention. It is a figure for demonstrating the structure of an induction heating means. It is a schematic diagram which shows another embodiment of the fixing device by an electromagnetic induction heating system. FIG. 6 is a diagram illustrating another embodiment of a fixing device provided in a color image forming apparatus according to the present invention. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2. FIG. 3 is a diagram schematically illustrating the shape of a toner according to the present invention.

Explanation of symbols

4 Developing device 10 Intermediate transfer belt (intermediate transfer member)
18 Image forming means 21 Exposure device 25 Fixing device 251 Heating roller 252 Fixing roller 253 Belt (toner heating member)
254 Pressure roller 40 Photosensitive member (latent image carrier)
22 Secondary transfer device 62 Primary transfer means 100 Copier main body 200 Paper feed table 300 Scanner 400 Automatic document feeder 70 Fixing device 701 Heating body 701a Excitation coil unit 701b Magnetic metal member 702 Film inner surface guide 703 Cylindrical film 704 Pressurization Roller 704a Core 704b Heat resistant rubber layer

Claims (11)

An image carrier that carries an electrostatic latent image corresponding to each color of yellow, cyan, magenta, and black;
A developing device corresponding to each color toner, which develops an electrostatic latent image of each color on the image carrier to form a toner image;
A transfer device that primarily transfers a toner image on the image carrier to an intermediate transfer member, and then secondary-transfers the toner images on the intermediate transfer member to a transfer target at once;
A color image forming apparatus comprising: a fixing device that fixes toner on the transfer body to form a toner image;
In the toner image obtained by the fixing device and having an L ^* value of 50 or more, the starting point of decrease in the methanol hydrophobicity of the toner forming the outermost layer is 28 ≦ methanol / (methanol + water) (volume%). There is provided a color image forming apparatus.
(However, the lightness L ^* is a value of a fixed image in which the toner is uniformly adhered on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. ) The color image forming apparatus according to claim 1.
A color image forming apparatus, wherein the toner image obtained by the fixing device and having an L ^* value of 50 or more contains at least yellow toner.
(However, the lightness L ^* is a value of a fixed image in which toner is uniformly deposited on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. ) The color image forming apparatus according to claim 1 or 2,
The plurality of developing devices are arranged in a tandem type,
The color image forming apparatus is characterized in that the order of arrangement of the developing devices is that the first is a yellow developing device and the fourth is a black developing device. The color image forming apparatus according to claim 3.
2. A color image forming apparatus according to claim 1, wherein the developing device is arranged in a second order of a cyan developing device and a third order of a magenta developing device. The color image forming apparatus according to any one of claims 1 to 4,
The color image forming apparatus, wherein the toner on the outermost layer of the toner image having an L ^* value of 50 or more obtained by the fixing device is a yellow toner. The color image forming apparatus according to any one of claims 1 to 5,
The color image forming apparatus integrally supports an image carrier that carries an electrostatic latent image and at least a developing device disposed to face the image carrier, and is a process that can be attached to and detached from the image forming apparatus main body. A color image forming apparatus comprising a cartridge. Forming an electrostatic latent image corresponding to each color of yellow, cyan, magenta and black on the image carrier;
A developing step of developing each color electrostatic latent image on the image carrier with a developing device corresponding to each color toner;
A transfer step in which the toner image on the image carrier is primarily transferred to an intermediate transfer member, and then the toner images on the intermediate transfer member are collectively transferred to a transfer target;
A color image forming method comprising: a fixing step of fixing a toner on the transfer body to form a toner image;
In the toner image having an L ^* value of 50 or more obtained by the fixing step, the starting point of decrease in the methanol hydrophobization degree of the toner forming the outermost layer is 28 ≦ methanol / (methanol + water) (volume%). There is provided a color image forming method.
(However, the lightness L ^* is a value of a fixed image in which the toner is uniformly adhered on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. ) The color image forming method according to claim 7,
A color image forming method, wherein the toner image obtained by the fixing step and having an L ^* value of 50 or more includes at least yellow toner.
(However, the lightness L ^* is a value of a fixed image in which toner is uniformly deposited on the transfer medium and the toner adhesion amount is 0.4 mg / cm ^2. ) The color image forming method according to claim 7 or 8,
The developing devices for each color used in the developing process are arranged in a tandem type,
The color image forming method, wherein the development order in the development step is yellow in the first and black in the fourth. The color image forming method according to claim 9.
The color image forming method, wherein the development order in the development step is cyan for the second and magenta for the third. The color image forming method according to any one of claims 7 to 10,
A color image forming method, wherein the toner on the outermost layer of a toner image having an L ^* value of 50 or more obtained by the fixing step is a yellow toner.

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