JP4780157B2 - Image forming apparatus and printed matter - Google Patents

Description

  The present invention relates to an image forming apparatus and printed matter.

  Recognizing the importance of protecting forest resources from the viewpoint of protecting the natural environment of the entire planet, reducing the use of resources has become an important issue. As part of reducing resource use, paper used in copiers, printers, etc. is being reused. Examples of the reuse method include a method (deinking process) in which a printed matter on which toner is fixed by an electrophotographic apparatus is beaten against a fiber to remove the toner, and then paper is made again as paper.

In order to efficiently perform the deinking process, a toner using a binder resin having a high alkali decomposability is disclosed. Specifically, for example, a toner using a polyhydroxyalkanoate having biodegradability as a binder resin (Patent Document 1), a toner using a degradable polyester resin made of polyhydroxycarboxylic acid (Patent Document 2), A toner containing a biodegradable lactic acid resin as a binder resin (Patent Document 3) is disclosed.
JP 2002-327047 A JP 2002-55491 A Japanese Patent Laid-Open No. 7-120975

  An object of the present invention is to provide an image forming apparatus in which an image excellent in deinking property is formed and high temperature offset during image formation is suppressed.

The above-mentioned subject is achieved by the following present invention.
That is, the invention according to claim 1
A first electrostatic latent image holding member, first electrostatic latent image forming means for forming a first electrostatic latent image on a surface of the first electrostatic latent image holding member, and a first toner image directly contacting a recording medium. A first developing means for developing the first electrostatic latent image with a developer containing a first toner for forming; and the first toner image formed by being developed by the first developing means. First toner image forming means including first transfer means for transferring so as to be in direct contact with the medium surface;
A second electrostatic latent image holder, second electrostatic latent image forming means for forming a second electrostatic latent image on the surface of the second electrostatic latent image holder, and the recording medium via the first toner image. Formed by developing the second electrostatic latent image with a developer containing a second toner for forming a second toner image formed on the surface, and developing the second electrostatic latent image with the second developing unit. One or a plurality of second toner image forming means including a second transfer means for transferring the second toner image to the surface of the recording medium;
Fixing means for fixing the first toner image and the second toner image transferred on the surface of the recording medium to the recording medium;
In the image forming apparatus, the softening temperature of the first toner is lower than the softening temperature of the second toner.

The invention according to claim 2
A recording medium, a non-colored toner image that is a first toner image formed in direct contact with the surface of the recording medium, and one or a plurality of first images formed on the surface of the recording medium via the first toner image. A colored toner image that is a two-toner image,
The softening temperature of the first toner image is lower than the softening temperature of the second toner image,
The softening temperature of the second toner image farthest from the recording medium among the second toner images is 90 ° C. or higher and 120 ° C. or lower,
The softening temperature of the second toner image farthest away is the highest temperature among the softening temperatures of the second toner image,
The first toner image is a printed matter having a larger L * value in the CIE 1976 (L * a * b *) color system than all the second toner images .

  According to the first aspect of the present invention, compared with the case where the softening temperature of the toner is not taken into consideration, an image having excellent deinking property is formed, and high temperature offset during image formation is suppressed.

According to the first aspect of the present invention, compared with the case where the softening temperature of the second toner for forming the farthest second toner image is out of the above range, the high temperature offset is further suppressed and the low temperature fixability is improved. improves.

According to the first aspect of the present invention, compared to the case where the softening temperature of the second toner for forming the farthest second toner image is not the highest temperature among the softening temperatures of the second toner, the image storability is improved. An excellent image is formed.

According to the first aspect of the present invention, an image in which coloring due to residual toner after deinking is suppressed is formed as compared with the case where the L * value of the toner is not taken into consideration.

According to the second aspect of the present invention, compared with the case where the softening temperature of the toner image is not taken into consideration, the deinking property is excellent, and the deterioration of the image due to the high temperature offset is suppressed.

According to the second aspect of the present invention, compared to the case where the softening temperature of the second toner image that is farthest away from the above range, image degradation due to higher temperature offset is suppressed.

According to the second aspect of the present invention, compared to the case where the softening temperature of the second toner image farthest away is not the highest temperature among the softening temperatures of the second toner image, the image storability is excellent.

According to the second aspect of the present invention, coloring due to the residual toner after the deinking process is suppressed as compared with the case where the L * value of the toner image is not taken into consideration.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is provided to the member which has the substantially same function throughout all the drawings, and the overlapping description may be abbreviate | omitted.

<First Embodiment>
[Image forming apparatus and image forming method]
FIG. 1 is a configuration diagram illustrating an image forming apparatus according to the first embodiment.

As shown in FIG. 1, the image forming apparatus 101 according to the first embodiment is a 5-color tandem full-color image forming apparatus. In the image forming apparatus 101 according to the first embodiment, toner for forming a contact toner image (first toner image) that is in direct contact with the recording medium (hereinafter referred to as “contact toner image forming toner”) may be referred to. ) Is a toner containing no colorant (hereinafter sometimes referred to as “non-colored toner”).
Hereinafter, a specific configuration of the image forming apparatus 101 will be described.

  The image forming apparatus 101 shown in FIG. 1 is a first electrophotographic system that outputs images of each color of black (K), magenta (M), cyan (C), and yellow (Y) based on color-separated image data. To fourth image forming units (hereinafter simply referred to as “units”) 10K, 10M, 10C, and 10Y. The image forming apparatus 101 includes an electrophotographic fifth unit 10S that forms a non-colored image that does not affect the color of the above-described colored image over the entire image area.

In the present embodiment, as described above, the non-colored toner image (hereinafter, referred to as “non-colored toner image”) formed by the fifth unit 10S in all areas where the image on the surface of the recording paper P exists. Is formed). Therefore, in any color image, the non-colored toner image becomes a contact toner image that directly contacts the recording paper P.
On the other hand, black, magenta, cyan, and yellow toner images formed by the first to fourth units 10K, 10M, 10C, and 10Y (hereinafter, “black toner image”, “magenta toner image”, and “cyan toner image”, respectively). Are sometimes formed only on the surface of the recording paper P where the non-colored toner image exists. Therefore, the black toner image, the magenta toner image, the cyan toner image, and the yellow toner image are non-contact toner images (second toner images) formed on the surface of the recording paper P through the contact toner images.

  In the present embodiment, the outermost toner image that is the non-contact toner image farthest from the recording paper P differs depending on the color-separated image data, that is, which type of toner image is used for image formation. Specifically, in this embodiment, when a black toner image is used for image formation, the black toner image is the outermost toner image. When a magenta toner image is used without using a black toner image, the magenta toner image is the outermost toner image. In addition, when a cyan toner image is used without using a black toner image and a magenta toner image, the cyan toner image is the outermost toner image. When only the yellow toner image is used without using the black toner image, the magenta toner image, and the cyan toner image, the yellow toner image is the top surface toner image.

These units 10K, 10M, 10C, 10Y, and 10S are arranged in parallel at a predetermined distance from each other in the horizontal direction. The units 10K, 10M, 10C, 10Y, and 10S may be process cartridges that are detachable from the main body of the image forming apparatus.
Above each of the units 10K, 10M, 10C, 10Y, and 10S, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. The vehicle travels in the direction toward 10Y. The support roller 24 is biased in a direction away from the drive roller 22 by a spring or the like (not shown), and a predetermined tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer member cleaning device 30 is provided on the side surface of the intermediate transfer belt 20 so as to face the drive roller 22.

In each of the developing devices (developing means) 4K, 4M, 4C, and 4Y of the units 10K, 10M, 10C, and 10Y, black, magenta, cyan, and yellow 4 accommodated in the toner cartridges 8K, 8M, 8C, and 8Y are provided. Color toner (hereinafter, referred to as “black toner”, “magenta toner”, “cyan toner”, and “yellow toner”) is supplied.
Further, the toner that does not contain the colorant (hereinafter, may be referred to as “non-colored toner”) contained in the toner cartridge 8S is supplied to the developing device 4S of the unit 10S.
In this embodiment, the non-colored toner supplied to the developing device 4S of the unit 10S is “contact toner image forming toner”. Further, black toner, magenta toner, cyan toner, and yellow toner supplied to the developing devices 4K, 4M, 4C, and 4Y of the units 10K, 10M, 10C, and 10Y are “non-contact toner image forming toners”. Further, in the present embodiment, among the non-contact toner image forming toner, the black toner supplied to the developing device 4K of the unit 10K is the “uppermost toner image forming toner”.

  In the present embodiment, the softening temperature of the toner used increases in the order of non-colored toner, yellow toner, cyan toner, magenta toner, and black toner. The black toner, magenta toner, cyan toner, and yellow toner all have a softening temperature of 90 ° C. or higher and 120 ° C. or lower.

That is, in the case of forming an image of any color, the softening temperature of the contact toner image forming toner (non-colored toner) is adjusted so that all non-contact toner image forming toners (black toner, magenta toner, cyan toner, And yellow toner).
In any color image, that is, no matter what non-contact toner image forming toner is the outermost toner image forming toner, the softening temperature of the outermost toner image forming toner is 90 ° C. or more and 120 ° C. or less, which is the highest temperature among all the toners used for image formation.

Further, in this embodiment, the L * value in the CIE 1976 (L * a * b *) color system of the non-colored toner is the L * value of the other toners (black toner, magenta toner, cyan toner, and yellow toner). The value is larger than.
Detailed description of the specific configuration and characteristics of the toner will be described later.

  Since the first to fifth units 10K, 10M, 10C, 10Y, and 10S described above have the same configuration, here, a black image disposed on the upstream side in the intermediate transfer belt traveling direction is formed. The first unit 10K will be described as a representative. In addition, by attaching a reference numeral with magenta (M), cyan (C), yellow (Y), and non-colored (S) instead of black (K) to the same part as the first unit 10K, The description of the second to fifth units 10M, 10C, 10Y, 10S is omitted.

  The first unit 10K includes a photoreceptor 1K (electrostatic latent image holder) that functions as an image holder. Around the photoreceptor 1K, a charging roller 2K (charging means) for charging the surface of the photoreceptor 1K to a predetermined potential, and the surface of the charged photoreceptor 1K is exposed by a laser beam 3K based on the color-separated image signal. Then, an exposure device 3 (electrostatic latent image forming means) for forming an electrostatic latent image, and a developing device 4K (development) for supplying the charged toner contained in the developer to the electrostatic latent image to develop the electrostatic latent image Means), a primary transfer roller 5K (transfer means) for transferring (primary transfer) a toner image formed by development by the developing device 4K onto the intermediate transfer belt 20, and the photoconductor 1K after the primary transfer. A photoreceptor cleaning device 6K for removing the toner remaining on the surface is disposed in order.

  The primary transfer roller 5K is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoreceptor 1K. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5K, 5M, 5C, 5Y, and 5S. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

Hereinafter, an operation of forming a black image in the first unit 10K will be described. First, prior to the operation, the surface of the photoreceptor 1K is charged to a potential of about −600 V to −800 V by the charging roller 2K (charging process).
The photoreceptor 1K is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3K. Therefore, a laser beam 3K is output to the surface of the charged photoconductor 1K via the exposure device 3 in accordance with black image data sent from a control unit (not shown). The laser beam 3K is applied to the photosensitive layer on the surface of the photoreceptor 1K, whereby an electrostatic latent image of a black print pattern is formed on the surface of the photoreceptor 1K (electrostatic latent image forming step).

The electrostatic latent image is an image formed on the surface of the photoreceptor 1K by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3K, and the charged charge on the surface of the photoreceptor 1K is changed. On the other hand, it is a so-called negative latent image formed by the remaining charge of the portion not irradiated with the laser beam 3K.
The electrostatic latent image formed on the photoreceptor 1K in this way is rotated to a predetermined development position as the photoreceptor 1K travels. At this development position, the electrostatic latent image on the photoreceptor 1K is visualized (developed) by the developing device 4K (development process).

  Black toner is accommodated in the developing device 4K. The black toner is triboelectrically charged by being agitated inside the developing device 4K, and has a charge of the same polarity (negative polarity) as the charged electric charge on the photosensitive member 1K, and a developer roll (developer holder). Is held on. Then, as the surface of the photoreceptor 1K passes through the developing device 4K, black toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1K, and the latent image is developed with the black toner. . The photoreceptor 1K on which the black toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1K is conveyed to a predetermined primary transfer position.

When the black toner image on the photoconductor 1K is conveyed to the primary transfer, a predetermined primary transfer bias is applied to the primary transfer roller 5K, and the electrostatic force from the photoconductor 1K toward the primary transfer roller 5K generates a toner image. The toner image on the photoreceptor 1K is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner. For example, in the fourth unit 10K, it is controlled to about +10 μA by a control unit (not shown).
On the other hand, the toner remaining on the photoreceptor 1K is removed and collected by the cleaning device 6K.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, 5Y, and 5S after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 to which the black toner image is transferred by the first unit 10K is sequentially conveyed through the second to fifth units 10M, 10C, 10Y, and 10S, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The
That is, in image formation using all the toners, the toner image transferred onto the intermediate transfer belt 20 is the black toner image, magenta toner image, cyan toner image, yellow toner image, The non-colored toner images are overlapped in this order.

  The intermediate transfer belt 20 onto which the four-color toner image and the non-colored toner image are transferred in a multiple manner through the first to fifth units is an image of the intermediate transfer belt 20 and the intermediate transfer belt 20 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roller 26 (transfer means) arranged on the holding surface side is reached to a secondary transfer portion. On the other hand, the recording paper P (recording medium) is fed at a predetermined timing to a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via a supply mechanism, and a predetermined secondary transfer bias is supplied to the support roller. 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P (transfer process). Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  The toner image transferred onto the recording paper P is configured by superimposing an uncolored toner image, a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image in order from the closest to the recording paper P. That is, the non-colored toner image is a contact toner image that is in direct contact with the recording paper P, and the yellow toner image, the cyan toner image, the magenta toner image, and the black toner image are formed on the recording paper P through the contact toner image. It is a formed non-contact toner image. Further, the black toner image is the outermost surface toner image farthest from the recording paper P among the non-contact toner images.

  Thereafter, the recording paper P is sent to the fixing device 28 (fixing means), the toner image is heated, and the color-superposed toner image is melted and fixed on the recording paper P (fixing step). The recording paper P on which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.

  As described above, the image forming apparatus 101 according to the present embodiment performs image formation.

  In the image forming apparatus 101 of the present embodiment, as described above, the softening temperature of the non-colored toner that is the contact toner image forming toner is set to the black toner, the magenta toner, the cyan toner, and the yellow that are the non-contact toner image forming toner. Lower than any softening temperature of the toner. Therefore, an image having excellent deinking properties is formed, and high temperature offset (that is, adhesion of melted toner to the heat fixing roll) during image formation is suppressed.

The reason is not clear, but is presumed as follows.
A toner that is a particular problem when reproducing paper as a recording medium is “hairy toner” that penetrates deep into the paper by fixing and is mixed with paper fibers. Of the toner images fixed on the paper, the toner near the surface farthest from the paper is often fully separated by mechanical processing such as kneading, but the toner fixed in the area closest to the paper is Often used as a hairy toner.

  Therefore, when an image is formed by transferring a plurality of toner images to the paper in order and fixing the toner image, the toner image fixed in the closest area to the paper, that is, the toner image that contacts and fixes the paper (contact toner image). ) To lower the softening temperature of the toner (contact toner image forming toner), the effect of softening the hairy toner by heating is increased. As a result, in the deinking step, the toner peeling action from the paper fiber by the deinking agent is enhanced, so that the deinking property is improved.

  In addition, since toner images other than contact toner images, that is, toners used for all non-contact toner images (non-contact toner image forming toners) have higher softening temperatures than contact toner image forming toners, High temperature offset is suppressed.

In the image forming apparatus 101 of the present embodiment, as described above, the softening temperature of the outermost toner image is 90 ° C. or higher and 120 ° C. or lower, so that high temperature offset in the fixing process is further suppressed and low temperature fixability is good.
Further, in the image forming apparatus 101 of the present embodiment, as described above, since the softening temperature of the outermost toner image is the highest among all the toners used, an image having excellent image storage stability is formed.

Further, in the image forming apparatus 101 of the present embodiment, as described above, the L * value of the non-colored toner that is the contact toner image forming toner is set to the black toner, the magenta toner, the cyan toner that is the non-contact toner image forming toner, Also, the value is larger than the L * value of yellow toner. That is, in this embodiment, among all the toners used, the toner having the largest L * value is used as the contact toner image forming toner.
Therefore, even if the contact toner image forming toner remains after the deinking process, since the L * value of the remaining toner (residual toner) is large, coloring due to the residual toner is suppressed.

  Further, in the image forming apparatus 101 of the present embodiment, non-colored toner is used as the contact toner image forming toner, and the non-colored toner does not affect the color of other colored toners. good.

  In the image forming apparatus 101 of the present embodiment, the softening temperature and L * value of the toner to be used are as described above. If the softening temperature of the non-colored toner is lower than the softening temperature of the other toners, It is not limited to this.

In the image forming apparatus 101 of this embodiment, the non-colored toner is used as the contact toner image forming toner. However, the present invention is not limited to this, and a toner colored yellow, cyan, magenta, or black may be used. However, toners colored in other colors may be used. Specifically, for example, as a toner for forming a contact toner image, instead of non-colored toner, a yellow toner that hardly influences the color of four colors is used, or a color close to the color of the recording paper P. Examples include a form using a colored toner.
In the image forming apparatus 101 of the present embodiment, the intermediate transfer belt 20 is transported in the above order when transported to the units 10K, 10M, 10C, 10Y, and 10S, but the unit 10S is the last. If so, the order of the other units 10K, 10M, 10C, 10Y may be changed.

In the image forming apparatus 101 of the present embodiment, the toner image is transferred to the recording paper P via the intermediate transfer belt 20, but the present invention is not limited to this configuration. May be transferred onto the recording paper. Even in the case where the toner image is directly transferred from the photosensitive member to the recording paper, the toner image that directly contacts the recording paper P becomes the contact toner image.
In the image forming apparatus 101 of the present embodiment, all the toner images stacked on the intermediate transfer belt 20 are transferred to the recording paper P by the secondary transfer roller 26. However, the present invention is not limited to this. The toner images may be individually transferred onto the recording paper P.

  Further, the image forming apparatus 101 of the present embodiment is a five-drum tandem full-color image forming apparatus, but is not limited thereto, and may be, for example, a rotary type image forming apparatus.

[Printed matter]
FIG. 2 is a cross-sectional view illustrating an example of a printed material manufactured by the image forming apparatus 101.
The printed material 110 is manufactured by the image forming apparatus 101 using all of the non-colored toner, yellow toner, cyan toner, magenta toner, and black toner.

  Specifically, the printed material 110 includes a recording paper P (recording medium), a non-colored toner image 114S (contact toner image) formed in direct contact with the surface of the recording paper P, and a non-colored toner image 114S. The yellow toner image 114Y, the cyan toner image 114C, the magenta toner image 114M, and the black toner image 114K (non-contact toner image) formed on the recording paper P are configured.

That is, the toner images are formed in the order of the non-colored toner image 114S, the yellow toner image 114Y, the cyan toner image 114C, the magenta toner image 114M, and the black toner image 114K from the closest side to the recording paper P.
Therefore, the non-colored toner image 114S is the contact toner image, the yellow toner image 114Y, the cyan toner image 114C, the magenta toner image 114M, and the black toner image 114K are the non-contact toner images, and the black toner image 114K is the above-described contact toner image. This is the outermost toner image.

  Details of the recording paper P will be described later. The toner image is a toner image formed on the recording paper P by the image forming apparatus 101 using the corresponding toner, and the forming method is as described above.

  In this embodiment, the softening temperatures of the toner images increase in the order of the non-colored toner image 114S, the yellow toner image 114Y, the cyan toner image 114C, the magenta toner image 114M, and the black toner image 114K. The black toner image 114K, the magenta toner image 114M, the cyan toner image 114C, and the yellow toner image 114Y all have a softening temperature of 90 ° C. or higher and 120 ° C. or lower.

  Further, in the present embodiment, the L * values in the CIE 1976 (L * a * b *) color system of the non-colored toner image 114S are other toner images (black toner image 114K, magenta toner image 114M, cyan toner image 114C). , And the L * value of the yellow toner image 114Y).

  Therefore, in the printed material 110, the softening temperature of the non-colored toner image 114S, which is a contact toner image, softens all the non-contact toner images (black toner image 114K, magenta toner image 114M, cyan toner image 114C, and yellow toner image 114Y). Lower than temperature. Therefore, it is excellent in deinking property and image degradation due to high temperature offset is suppressed.

Further, in the printed material 110, since the softening temperature of the black toner image 114K that is the outermost surface toner image is 90 ° C. or higher and 120 ° C. or lower, image deterioration due to high temperature offset is further suppressed.
In the printed material 110, the black toner image 114K, which is the outermost toner image among all the toner images, has the highest softening temperature, and thus has excellent image storage stability.

  Further, in the printed material 110, among all the toner images, the non-colored toner image 114S having the largest L * value is used as the contact toner image. Therefore, coloring due to residual toner after the deinking process is suppressed.

  Note that the printed material 110 is an image formed using all the toner as described above, but the printed material manufactured by the image forming apparatus 101 of the present embodiment is not limited to this, and is used according to the color of the image. A toner is appropriately selected. However, in the case of forming an image of any color, the non-colored toner image 114S is formed in direct contact with the surface of the recording paper P, and other colors are formed on the recording paper P through the non-colored toner image 114S. The toner images are formed singly or in layers. Therefore, since the non-colored toner image 114S is formed over the entire image portion and plays a role like a base, the above-described deinking effect and the effect of suppressing image deterioration can be obtained, and the non-colored toner image 114S can be used for the color of the image. Thus, an image with good color reproducibility is formed.

  In this embodiment, the softening temperature and L * value of the toner image are as described above. However, if the softening temperature of the non-colored toner image 114S is lower than the softening temperature of the other toner images, the present invention is not limited to this. I can't.

In this embodiment, the non-colored toner image 114S is used as the contact toner image, but the present invention is not limited to this. Specifically, for example, a yellow toner image may be used instead of the non-colored toner image 114S as the contact toner image, or the contact toner image is colored in a color close to the color of the recording paper P instead of the non-colored toner image 114S. A toner image may be used.
In the printed material 110, the toner images are formed in the above order. However, the present invention is not limited to this as long as the non-colored toner image 114S is formed in direct contact with the recording paper P, and the black toner image 114K and the magenta toner image 114M. The order of the cyan toner image 114C and the yellow toner image 114Y may be switched.

<Second Reference Example >
[Image forming apparatus and image forming method]
FIG. 3 is a configuration diagram illustrating an image forming apparatus according to a second reference example .

As shown in FIG. 3, the image forming apparatus 102 according to the second reference example is a quadruple tandem full-color image forming apparatus. The image forming apparatus 102 according to the second reference example has a configuration in which yellow toner is used as contact toner image forming toner without using non-colored toner.
That is, the image forming apparatus 102 illustrated in FIG. 3 includes the first to fourth units 10K, 10M, 10C, and 10Y, but does not include the fifth unit 10S.

In this reference example , the yellow toner image formed by the fourth unit 10Y is a contact toner image, and the yellow toner image is formed in all areas where the image on the surface of the recording paper P exists. Therefore, in any color image formation, the yellow toner image becomes a contact toner image that directly contacts the recording paper P.

In this reference example , the softening temperature of the toner used increases in the order of yellow toner, cyan toner, magenta toner, and black toner. The black toner, magenta toner, and cyan toner all have a softening temperature of 90 ° C. or higher and 120 ° C. or lower.

That is, the softening temperature of the contact toner image forming toner (non-colored toner) is lower than the softening temperature of all the non-contact toner image forming toners (black toner, magenta toner, and cyan toner).
The softening temperature of the toner for forming the outermost toner image (black toner, magenta toner, or cyan toner) is 90 ° C. or higher and 120 ° C. or lower, which is the highest temperature among all the toners used for image formation. .

Furthermore, in this reference example , the L * value in the CIE 1976 (L * a * b *) color system of yellow toner is larger than the L * values of other toners (black toner, magenta toner, and cyan toner). It is a value.

In this reference example , in the image formation using all the toners, the toner image transferred onto the surface of the intermediate transfer belt 20 is the black toner image, magenta toner image, cyan toner image from the closest side to the intermediate transfer belt 20. The yellow toner images are overlapped in this order.
Further, the toner image transferred onto the recording paper P is composed of a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image which are overlapped in this order from the closest side to the recording paper P.

  That is, the yellow toner image is a contact toner image that is in direct contact with the recording paper P, and the cyan toner image, the magenta toner image, and the black toner image are formed on the recording paper P through the contact toner image. It is a toner image. Further, the black toner image is the outermost surface toner image farthest from the recording paper P among the non-contact toner images.

  Except for these, the configuration is the same as that of the image forming apparatus 101 in the first embodiment, and a description thereof will be omitted.

In the image forming apparatus 102 of this reference example , as described above, the softening temperature of the yellow toner that is a contact toner image forming toner is any of black toner, magenta toner, and cyan toner that are non-contact toner image forming toners. Lower than softening temperature. Accordingly, an image having excellent deinking properties is formed, high temperature offset during image formation is suppressed, and toner aggregation in the image forming apparatus is suppressed.

In the image forming apparatus 102 of this reference example , since the softening temperature of the outermost surface toner image is 90 ° C. or higher and 120 ° C. or lower as described above, the high temperature offset in the fixing step is further suppressed and the low temperature fixing property is good.
In the image forming apparatus 102 of this reference example , as described above, the softening temperature of the outermost toner image is the highest among all the toners used, and thus an image having excellent image storage stability is formed.

Further, in the image forming apparatus 102 of this reference example , as described above, the toner having the largest L * value is used as the contact toner image forming toner among all the toners used. Therefore, coloring due to residual toner after the deinking process is suppressed.

In the image forming apparatus 102 of this reference example , the softening temperature and L * value of the toner used are as described above. However, if the softening temperature of the yellow toner is lower than the softening temperatures of the other toners, Not limited to.

In the image forming apparatus 102 of this reference example , when the intermediate transfer belt 20 is transported to the units 10K, 10M, 10C, and 10Y, it is transported in the above order. The order of the other units 10K, 10M, and 10C may be changed.
Further, the order of the units 10K, 10M, 10C, and 10Y may be changed as long as the softening temperature of the contact toner image forming toner is lower than the softening temperature of all other non-contact toner image forming toners. The type of unit may be increased or decreased.

[Printed matter]
The printed matter produced by the image forming apparatus 102 according to the second reference example using all the toners of yellow toner, cyan toner, magenta toner, and black toner is recorded on recording paper P (recording medium) and recording paper P. A yellow toner image (contact toner image) formed in direct contact with the surface, and a cyan toner image, a magenta toner image, and a black toner image (non-contact toner image) formed on the recording paper P via the yellow toner image. And is constituted by.

In this reference example , the softening temperature of the toner image increases in the order of yellow toner image, cyan toner image, magenta toner image, and black toner image. The black toner image, the magenta toner image, and the cyan toner image all have a softening temperature of 90 ° C. or higher and 120 ° C. or lower.

Further, in this reference example , the L * value in the CIE 1976 (L * a * b *) color system of the yellow toner image is the L * value of the other toner images (black toner image, magenta toner image, and cyan toner image). The value is larger than the value.

Therefore, in the printed matter of this reference example , the softening temperature of the yellow toner image that is the contact toner image is lower than the softening temperature of all the non-contact toner images (black toner image, magenta toner image, and cyan toner image). Therefore, it is excellent in deinking property and image degradation due to high temperature offset is suppressed.

In the printed material of this reference example , the softening temperature of the black toner image, which is the outermost toner image, is 90 ° C. or higher and 120 ° C. or lower, so that image deterioration due to high temperature offset is further suppressed.
In the printed matter of this reference example , the black toner image, which is the outermost toner image among all the toner images, has the highest softening temperature, and thus has excellent image storage stability.

Furthermore, in the printed matter of this reference example, the yellow toner image having the largest L * value among all the toner images is used as the contact toner image. Therefore, coloring due to residual toner after the deinking process is suppressed.

In the printed matter of this reference example , the softening temperature and L * value of the toner image are as described above. However, if the softening temperature of the yellow toner image is lower than the softening temperatures of the other toner images, this is not necessary. Not limited.

In the printed matter of this reference example , the toner images are formed in the above order. However, the present invention is not limited to this as long as a yellow toner image is formed by direct contact with the recording paper P. A black toner image, a magenta toner image, Also, the order of the cyan toner images may be changed.
In this reference example , if the softening temperature of the contact toner image formed by direct contact with the recording paper P is lower than the softening temperatures of all other non-contact toner images, the toner image The order may be changed, and the types of toner images may be increased or decreased.

<Third reference example >
[Image forming apparatus and image forming method]
FIG. 4 is a configuration diagram illustrating an image forming apparatus according to a third reference example .

As shown in FIG. 4, the image forming apparatus 103 according to the third reference example is a 5-color tandem full-color image forming apparatus. The image forming apparatus 103 according to the third reference example uses a yellow toner as the contact toner image forming toner and uses a non-colored toner as the outermost toner image forming toner.

  The image forming apparatus 103 shown in FIG. 4 outputs a first unit 10S that forms a non-colored image that does not affect the color of the colored image over the entire image area, and an image of each color based on the color-separated image data. The second to fifth units 10K, 10M, 10C, and 10Y are provided.

In this reference example , the yellow toner image formed by the fifth unit 10Y is a contact toner image, and the yellow toner image is formed in all areas where the image on the surface of the recording paper P exists. Therefore, in any color image formation, the yellow toner image becomes a contact toner image that directly contacts the recording paper P.

In the present reference example , the non-colored toner image formed by the first unit 10S is formed in all the areas where the image on the surface of the recording paper P exists. Therefore, in any color image, the non-colored toner image becomes the outermost toner image.

In this reference example , the softening temperature of yellow toner is lower than the softening temperatures of all non-contact toner image forming toners (non-colored toner, black toner, magenta toner, and cyan toner).
The softening temperature of the non-colored toner that is the toner for forming the outermost surface toner image is 90 ° C. or higher and 120 ° C. or lower, which is the highest temperature among all the toners used for image formation.

In this reference example , in the image formation using all the toners, the toner image transferred onto the surface of the intermediate transfer belt 20 is the non-colored toner image, black toner image, magenta from the closest side to the intermediate transfer belt 20. The toner image, the cyan toner image, and the yellow toner image are overlapped in this order.
Further, the toner image transferred onto the recording paper P is composed of the yellow toner image, the cyan toner image, the magenta toner image, the black toner image, and the non-colored toner image which are overlapped in this order from the closest side to the recording paper P. .

  That is, the yellow toner image is a contact toner image that is in direct contact with the recording paper P, and the cyan toner image, the magenta toner image, the black toner image, and the non-colored toner image are formed on the recording paper P through the contact toner image. It is a formed non-contact toner image. Further, the non-colored toner image is the outermost surface toner image farthest from the recording paper P among the non-contact toner images.

  Except for these, the configuration is the same as that of the image forming apparatus 101 in the first embodiment, and a description thereof will be omitted.

In the image forming apparatus 103 of this reference example , as described above, the softening temperature of the yellow toner, which is a contact toner image forming toner, is the non-colored toner, the black toner, the magenta toner, and the cyan, which are non-contact toner image forming toners. Lower than any softening temperature of the toner. Accordingly, an image having excellent deinking properties is formed, high temperature offset during image formation is suppressed, and toner aggregation in the image forming apparatus is suppressed.

In the image forming apparatus 103 of this reference example , since the softening temperature of the non-colored toner is 90 ° C. or higher and 120 ° C. or lower as described above, the high temperature offset in the fixing step is further suppressed and the low temperature fixing property is good. In the image forming apparatus 103 of this reference example , as described above, among all the toners used, the non-colored toner has the highest softening temperature, and thus an image having excellent image storage stability is formed.
Further, in the image forming apparatus 103 of the present reference example, the non-colored toner image is the outermost toner image when an image of any color is formed. Therefore, an image having good image storage stability is formed regardless of the softening temperatures of the cyan toner, magenta toner, and black toner to be used. Further, even when cyan, magenta, and black toners having different softening temperatures are used to form images having various colors, uneven fixing characteristics and image storability are less likely to occur.
Further, in the image forming apparatus 103 of this reference example, the yellow toner that does not easily affect the color is used as the contact toner image forming toner, and the non-colored toner is used as the outermost toner image forming toner. Good reproducibility.

In the image forming apparatus 103 of this reference example , the softening temperature of the toner to be used is as described above. However, the present invention is not limited to this as long as the softening temperature of the yellow toner is lower than the softening temperatures of the other toners. .

In the image forming apparatus 103 of this reference example , when the intermediate transfer belt 20 is transported to the units 10S, 10K, 10M, 10C, and 10Y, it is transported in the above order, but the unit 10S is the first. If the unit 10Y is the last, the order of the other units 10K, 10M, and 10C may be changed.

[Printed matter]
A printed matter produced by the image forming apparatus 103 according to the third reference example using all toners of yellow toner, cyan toner, magenta toner, black toner, and non-colored toner is a recording paper P (recording medium), A yellow toner image (contact toner image) formed in direct contact with the surface of the recording paper P, and a cyan toner image, a magenta toner image, a black toner image, and a non-image formed on the recording paper P via the yellow toner image. And a colored toner image (non-contact toner image).

In the printed material of this reference example , the softening temperature of the yellow toner image that is the contact toner image is higher than the softening temperature of all the non-contact toner images (non-colored toner image, black toner image, magenta toner image, and cyan toner image). Low. Therefore, it is excellent in deinking property and image degradation due to high temperature offset is suppressed.

Further, in the printed matter of this reference example , the softening temperature of the non-colored toner image that is the outermost toner image is 90 ° C. or higher and 120 ° C. or lower, so that image deterioration due to high temperature offset is further suppressed.
Further, in the printed matter of this reference example , among all the toner images, the non-colored toner image that is the outermost toner image has the highest softening temperature, and thus has excellent image storage stability.
In the printed material of this reference example , the yellow toner image is used as the contact toner image, the non-colored toner image is used as the outermost toner image, and the yellow toner image and the non-colored toner image are formed over the entire image portion. In addition, the effect of color reproducibility can be obtained while obtaining the effects of deinking, image deterioration suppression, and image storage.

In the printed matter of this reference example , the softening temperature of the toner image is as described above, but the invention is not limited to this as long as the softening temperature of the yellow toner image is lower than the softening temperatures of the other toner images.
In the printed matter of this reference example , the toner images are formed in the above order. However, if the softening temperature of the contact toner image is lower than the softening temperatures of all other non-contact toner images, the order of the toner images is as follows. May be replaced, and the type of toner image may be increased or decreased.

<Fourth Reference Example >
[Image forming apparatus and image forming method]
FIG. 5 is a configuration diagram illustrating an image forming apparatus according to a fourth reference example .

The image forming apparatus 104 according to the fourth reference example is a monochrome image forming apparatus as shown in FIG. The image forming apparatus 104 according to the fourth reference example uses two types of black toner of the same color having different softening temperatures. Specifically, the black toner having the lower softening temperature (second black toner) is used as the contact toner image forming toner, and the black toner having the higher softening temperature (first black toner) is used as the outermost surface toner image. Used as a forming toner.

The specific configuration of the image forming apparatus 104 shown in FIG. 5 includes first and second units 10K and 10B that form a black image over the entire image area.
In this reference example , the second black toner image formed by the second unit 10B is a contact toner image. The first black toner image formed by the first unit 10K is a non-contact toner image and an outermost toner image.

In this reference example , the softening temperature of the second black toner used for forming the second black toner image is lower than the softening temperature of the first black toner used for forming the first black toner image. The softening temperature of the first black toner is 90 ° C. or higher and 120 ° C. or lower.

In this reference example , the toner image transferred onto the surface of the intermediate transfer belt 20 is configured by overlapping the first black toner image and the second black toner image in this order from the closest side to the intermediate transfer belt 20. ing.
Further, the toner image transferred onto the recording paper P is configured by overlapping the second black toner image and the first black toner image in this order from the closest side to the recording paper P.

  Except for these, the configuration is the same as that of the image forming apparatus 101 in the first embodiment, and a description thereof will be omitted.

In the image forming apparatus 104 of this reference example , as described above, the softening temperature of the second black toner that is a contact toner image forming toner is higher than the softening temperature of the first black toner that is a non-contact toner image forming toner. Is also low. Accordingly, an image having excellent deinking properties is formed, high temperature offset during image formation is suppressed, and toner aggregation in the image forming apparatus is suppressed.

In the image forming apparatus 104 of this reference example , as described above, since the softening temperature of the first black toner is 90 ° C. or higher and 120 ° C. or lower, high temperature offset in the fixing process is further suppressed and low temperature fixability is good. .
In the image forming apparatus 104 of this reference example , as described above, the first black toner has the highest softening temperature among all the toners used, and thus an image having excellent image storage stability is formed.

In the image forming apparatus 104 of this reference example , as described above, two types of black toner of the same color are used. However, the present invention is not limited to this, and the toner color may be appropriately selected according to the color of the image to be formed. Good. Also, the two types of toner may have different colors. Specifically, for example, a non-colored toner is used as the contact toner image forming toner, and a black toner is used as the outermost toner image forming toner.

[Printed matter]
The printed matter produced by the image forming apparatus 104 according to the fourth reference example is a recording paper P (recording medium) and a second black toner image (contact toner image) formed in direct contact with the surface of the recording paper P. And a first black toner image (non-contact toner image) formed on the recording paper P via the second black toner image.

In the printed matter of this reference example , the softening temperature of the second black toner image that is a contact toner image is lower than the softening temperature of the first black toner image that is a non-contact toner image. Therefore, it is excellent in deinking property and image degradation due to high temperature offset is suppressed.

In the printed matter of this reference example , the softening temperature of the first black toner image, which is the outermost toner image, is 90 ° C. or higher and 120 ° C. or lower, so that image deterioration due to high temperature offset is further suppressed.
In the printed matter of this reference example , the first black toner image, which is the outermost toner image among all the toner images, has the highest softening temperature, and therefore has excellent image storage stability.

In the printed matter of this reference example , both the contact toner image and the outermost surface toner image are black toner images. However, as long as the softening temperatures of the contact toner image and the outermost surface toner image satisfy the above relationship, the present invention is not limited thereto. The color of the toner image may be appropriately selected according to the color of the image to be formed. Specifically, for example, both the contact toner image and the outermost surface toner image may be cyan toner images, or the contact toner image may be an uncolored toner image and the outermost surface toner image may be a black toner image. Good.

<Toner>
Hereinafter, the toner used in the embodiment will be described in detail.

  The toner contains at least a binder resin, and may contain a colorant, a release agent, and other components as necessary.

-Binder resin-
The binder resin is not particularly limited. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, acrylic Esters having vinyl groups such as lauryl acid, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; single quantities of polyolefins such as ethylene, propylene and butadiene Homopolymer consisting of, or copolymers obtained by combining two or more of these, more mixtures thereof.
In addition, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or a mixture of these with the vinyl resin, or vinyl monomers in the presence of these resins Examples thereof include a graft polymer obtained by polymerization.

Styrene resin, (meth) acrylic resin, and styrene- (meth) acrylic copolymer resin are known methods, for example, by combining the following styrene monomer and (meth) acrylic monomer alone or in appropriate combination. Manufactured by.
Specific examples of the styrene monomer include styrene, α-methyl styrene, vinyl naphthalene, 2-methyl styrene, 3-methyl styrene, 4-methyl styrene, 2-ethyl styrene, and 3-ethyl styrene. , Alkyl-substituted styrene having an alkyl chain such as 4-ethylstyrene, halogen-substituted styrene such as 2-chlorostyrene, 3-chlorostyrene and 4-chlorostyrene, fluorine-substituted such as 4-fluorostyrene and 2,5-difluorostyrene Examples include styrene. Specific examples of the (meth) acrylic acid monomer include (meth) acrylic acid, n-methyl (meth) acrylate, n-ethyl (meth) acrylate, and (meth) acrylic acid. n-propyl, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, ( N-decyl (meth) acrylate, n-dodecyl (meth) acrylate, n-lauryl (meth) acrylate, n-tetradecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n (meth) acrylate -Octadecyl, isopropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Amyl crylate, neopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate, (meth ) Biphenyl acrylate, diphenylethyl (meth) acrylate, t-butylphenyl (meth) acrylate, terphenyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth ) Dimethylaminoethyl acrylate, diethylaminoethyl (meth) acrylate, methoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid-β-carboxyethyl, (meth) acrylonitrile, (meth ) Acrylamide Etc. These monomers are appropriately combined to produce by a known method.

  When using a styrene resin, a (meth) acrylic resin or a copolymer resin thereof as a binder resin, the weight average molecular weight Mw is 20,000 or more and 100,000 or less, and the number average molecular weight Mn is 2,000 or more and 30,000 or less. It is desirable to use the thing of the range. On the other hand, when a polyester resin is used as the binder resin, a resin having a weight average molecular weight Mw of 5,000 or more and 40,000 or less and a number average molecular weight Mn of 2,000 or more and 10,000 or less may be used. desirable.

  The glass transition temperature of the styrene resin, (meth) acrylic resin, and these copolymer resins is preferably in the range of 40 ° C. or higher and 80 ° C. or lower. When the glass transition temperature is in the above range, the heat-resistant blocking property and the minimum fixing temperature are maintained.

  As the polyester resin, for example, a crystalline polyester resin or an amorphous polyester resin is used, and one synthesized from a polyvalent carboxylic acid component and a polyhydric alcohol component is desirable. In addition, as said polyester resin, a commercial item may be used and what was synthesize | combined may be used.

  Here, the “crystalline polyester resin” refers to a resin having a clear endothermic peak rather than a stepwise endothermic amount change in differential scanning calorimetry (DSC). On the other hand, a resin in which a stepwise endothermic change is recognized in DSC means an “amorphous polyester resin”.

  Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, fumaric acid, glutaric acid, adipic acid, peric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Aliphatic dicarboxylic acids such as 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malon Aromatic dicarboxylic acids such as dibasic acids such as acid and mesaconic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and the like, and these anhydrides and lower alkyl esters thereof are also included. is not.

  Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like, and anhydrides thereof. And lower alkyl esters. These may be used individually by 1 type and may use 2 or more types together.

  Furthermore, in addition to the aforementioned aliphatic dicarboxylic acid and aromatic dicarboxylic acid, a dicarboxylic acid component having a double bond may be contained. A dicarboxylic acid having a double bond is preferably used in order to prevent hot offset at the time of fixing in that it can be crosslinked radically through a double bond. Examples of the dicarboxylic acid include, but are not limited to, maleic acid, fumaric acid, 3-hexenedioic acid, and 3-octenedioic acid. In addition, these lower esters, acid anhydrides and the like are also included. Among these, fumaric acid, maleic acid and the like are mentioned in terms of cost.

  Examples of the polyhydric alcohol component include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin; cyclohexanediol, cyclohexanedimethanol, hydrogenated Alicyclic diols such as bisphenol A; aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A; and the like, and one or more of these polyhydric alcohols are used. Also good.

  In the case of an amorphous polyester resin, among these polyhydric alcohols, aromatic diols and alicyclic diols are desirable, and aromatic diols are more desirable. On the other hand, in the case of a crystalline polyester resin, an aliphatic diol is desirable, and a linear aliphatic diol having 7 to 20 carbon atoms in the main chain portion is more desirable. When the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that good toner blocking resistance, image storage stability, and low-temperature fixability may not be obtained. Further, when the number of carbon atoms is less than 7, when the polycondensation with aromatic dicarboxylic acid is performed, the melting point becomes high and fixing at low temperature may be difficult. On the other hand, when the number exceeds 20, it is difficult to obtain practical materials. easy. The carbon number is more preferably 14 or less.

  Specific examples of the aliphatic diol suitably used for the synthesis of the crystalline polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1 , 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1, Examples include, but are not limited to, 13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosandecanediol, and the like. Among these, considering availability, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are desirable.

  Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like. These may be used individually by 1 type and may use 2 or more types together.

  Of the polyhydric alcohol components preferably used for the synthesis of the crystalline polyester, the content of the aliphatic diol component is desirably 80 mol% or more, and more desirably 90 mol% or more. When the content of the aliphatic diol component is less than 80 mol%, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that good toner blocking resistance, image storage stability and low-temperature fixability may not be obtained. is there.

  If necessary, a monovalent acid such as acetic acid or benzoic acid or a monovalent alcohol such as cyclohexanol or benzyl alcohol may be used for the purpose of adjusting the acid value or the hydroxyl value.

  The polyester resin is produced by subjecting the polyhydric alcohol and polyhydric carboxylic acid to a condensation reaction according to a conventional method. For example, a catalyst is added to the polyhydric alcohol and polyhydric carboxylic acid, if necessary, and blended in a reaction vessel equipped with a thermometer, a stirrer, and a flow-down condenser, and in the presence of an inert gas (such as nitrogen gas). , Heated at 150 to 250 ° C to continuously remove by-product low-molecular compounds out of the reaction system, stop the reaction when a predetermined acid value is reached, cool, and obtain the desired reactant Manufactured by doing.

  Examples of the catalyst used for the synthesis of this polyester resin include esterification catalysts such as organic metals such as dibutyltin dilaurate and dibutyltin oxide, and metal alkoxides such as tetrabutyl titanate. The amount of the catalyst added is desirably 0.01 to 1% by mass with respect to the total amount of raw materials.

  The molecular weight of the amorphous polyester resin used for the toner is a molecular weight measured by the gel permeation chromatography (GPC) method of the soluble content of tetrahydrofuran (THF), and the weight average molecular weight (Mw) is in the range of 5000 to 200000. More preferably, it is in the range of 7000 to 100,000, the number average molecular weight (Mn) is preferably in the range of 2000 to 10,000, and the molecular weight distribution Mw / Mn is in the range of 1.5 to 50. Desirably, it is preferably in the range of 2 to 10.

  The crystalline polyester resin preferably has a weight average molecular weight (Mw) of 5000 to 70000, more preferably 15000 to 50000, and a number average molecular weight (Mn) of 2000 to 20000. Desirably, the molecular weight distribution Mw / Mn is desirably in the range of 1.5 to 10, more preferably in the range of 2.0 to 4.0.

  When the weight average molecular weight and the number average molecular weight are smaller than the above ranges, while effective for low-temperature fixability, not only the hot offset resistance is remarkably deteriorated, but also the glass transition point of the toner is lowered. The storage stability such as toner blocking may be adversely affected. On the other hand, if the molecular weight is larger than the above range, the hot offset resistance is sufficiently imparted, but the low-temperature fixability is lowered, and the bleeding of the crystalline polyester phase present in the toner is inhibited, so that the document is stored. May adversely affect sex. Therefore, by satisfying the above conditions, it becomes easy to achieve both low-temperature fixability, hot offset resistance, and document storage stability.

  Here, the measurement of the said weight average molecular weight (and number average molecular weight) was performed on condition by the following gel permeation chromatography (GPC). GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μL, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

  The acid value of the polyester resin (the number of mg of KOH required to neutralize 1 g of resin) is easy to obtain the above-mentioned preferred molecular weight distribution, and it is easy to ensure the granulation property of the toner particles by the emulsion dispersion method. The environmental stability of the obtained toner (the stability of the chargeability when the temperature and humidity change) is easily maintained. Therefore, it is desirable that the toner be in the range of 1 to 30 mgKOH / g. The acid value of the polyester resin is adjusted by controlling the carboxyl group at the terminal of the polyester by the blending ratio and reaction rate of the raw material polycarboxylic acid and polyhydric alcohol. Or what has a carboxyl group in the principal chain of polyester is obtained by using trimellitic anhydride as a polyvalent carboxylic acid component.

  The glass transition temperature of the amorphous polyester resin is preferably in the range of 35 to 100 ° C., and more preferably 50 to 80 ° C. from the viewpoint of the balance between storage stability and toner fixability. When the glass transition temperature is less than 35 ° C., the toner tends to be blocked during the storage or in the developing machine (a phenomenon in which toner particles are aggregated into a lump). On the other hand, when the glass transition temperature exceeds 100 ° C., the fixing temperature of the toner becomes high, which is not desirable.

The melting point of the crystalline polyester resin is desirably in the range of 60 to 120 ° C, and more preferably in the range of 70 to 100 ° C. When the melting point of the crystalline polyester resin is less than 60 ° C., the powder is likely to be aggregated or the storage stability of the fixed image may be deteriorated. On the other hand, if the temperature exceeds 120 ° C., image roughness may occur and low-temperature fixability may be impaired.
In addition, melting | fusing point of the said crystalline polyester resin was calculated | required as the peak temperature of the endothermic peak obtained by the said differential scanning calorimetry (DSC).

-Colorant-
The colorant is not particularly limited as long as it is a known colorant. For example, carbon black such as furnace black, channel black, acetylene black, and thermal black, inorganic pigments such as bengara, bitumen, and titanium oxide, fast yellow, disazo Azo pigments such as yellow, pyrazolone red, chelate red, brilliant carmine and para brown; phthalocyanine pigments such as copper phthalocyanine and metal-free phthalocyanine; Ring pigments; and the like.

  Specifically, Chrome Yellow, Hansa Yellow, Benzidine Yellow, Slen Yellow, Quinoline Yellow, Permanent Orange GTR, Pyrarozone Orange, Vulcan Orange, Watch Young Red, Permanent Red, Dupont Oil Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment 57: 1, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Examples thereof include various pigments such as CI Pigment Blue 15: 3, and these are used alone or in combination of two or more.

The content of the colorant is preferably in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Further, if necessary, a surface-treated colorant may be used, or a pigment dispersant may be used. It is also effective to use. By selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.
However, the non-colored toner is a toner that does not contain the colorant.

-Release agent-
The release agent is not particularly limited as long as it is a known release agent. For example, natural waxes such as carnauba wax, rice wax, and candelilla wax; low molecular weight polypropylene, low molecular weight polyethylene, sazole wax, microcrystalline Examples include, but are not limited to, synthesis of wax, Fischer-Tropsch wax, paraffin wax, montan wax and the like, or mineral / petroleum wax; ester wax such as fatty acid ester and montanic acid ester. Moreover, these mold release agents may be used individually by 1 type, and may be used together 2 or more types.

  The melting point of the release agent is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher, from the viewpoint of storage stability. Further, from the viewpoint of offset resistance, the temperature is desirably 110 ° C. or less, and more desirably 100 ° C. or less.

  The content of the release agent is preferably in the range of 2 to 30 parts by mass and more preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the binder resin. If the content of the release agent is less than 2 parts by mass, the effect of adding the release agent is not obtained, and hot offset at a high temperature may be caused. On the other hand, if the amount exceeds 30 parts by mass, the chargeability may be adversely affected, and the mechanical strength of the toner tends to be reduced. There is.

-Other ingredients-
In addition to the above components, various components such as an internal additive, a charge control agent, inorganic powder (inorganic particles), and organic particles may be added to the toner as necessary.

Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and magnetic materials such as compounds containing these metals.
When the magnetic material is used as a magnetic toner, the ferromagnetic particles preferably have an average particle size of 2 μm or less, more preferably about 0.1 to 0.5 μm. The amount contained in the toner is preferably 20 to 200 parts by mass with respect to 100 parts by mass of the resin component, and particularly preferably 40 to 150 parts by mass with respect to 100 parts by mass of the resin component. Further, it is desirable that the magnetic characteristics at the application of 10K oersted are those having a coercive force (Hc) of 20 to 300 oersted, saturation magnetization (σs) of 50 to 200 emu / g, and residual magnetization (σr) of 2 to 20 emu / g.

  Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments.

  The inorganic powder is added mainly for the purpose of adjusting the viscoelasticity of the toner. For example, normal toners such as silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, and cerium oxide are listed in detail below. All inorganic particles used as surface external additives can be mentioned.

Examples of inorganic particles and organic particles externally added to the toner surface include the following.
Examples of inorganic particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride, Examples include Bengala, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, and silicon nitride. Among these, silica particles and titanium oxide particles are desirable, and particles that have been subjected to hydrophobic treatment are particularly desirable.

Inorganic particles are generally used for the purpose of improving fluidity. The primary particle diameter of the inorganic particles is desirably in the range of 1 to 200 nm, and the addition amount is desirably in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the toner.
Organic particles are generally used for the purpose of improving cleaning properties and transfer properties. Specifically, for example, fluorine resin powders such as polyvinylidene fluoride and polytetrafluoroethylene, fatty acid metal salts such as zinc stearate and calcium stearate. , Polystyrene, polymethyl methacrylate and the like.

-Toner production method-

  Examples of the method for producing the toner include a kneading and pulverizing method and a wet granulation method. Examples of the wet granulation method include known melt suspension methods, emulsion aggregation / unification methods, dissolution suspension methods, and the like. Among these, emulsion aggregation methods are preferably used.

The emulsion aggregation method includes an emulsification step in which each raw material such as a polyester resin and a colorant is dispersed in an aqueous dispersion medium, an aggregation step in which aggregated particles are produced from a raw material dispersion obtained by mixing each dispersion, and the aggregated particles. At least a fusing step of fusing to obtain toner. In addition, a coating step (shell layer forming step) for covering the surface of the aggregated particles with the same or different resin particles as the binder resin is included as necessary.
Hereinafter, each step will be described in detail.

(Emulsification process)
In the emulsion aggregation method, since the binder resin and the colorant are mixed as respective emulsified particles as a raw material dispersion, the emulsification step is a step of preparing an emulsified dispersion of the above raw material. Therefore, first, the binder resin needs to be dispersed in advance as resin particles in the raw material dispersion.

  The volume average particle diameter of the emulsified resin particles is preferably 0.01 to 1 μm, more preferably 0.03 to 0.8 μm, and further preferably 0.03 to 0.6 μm. When the average particle diameter exceeds 1 μm, the particle diameter distribution of the finally obtained toner for developing an electrostatic latent image is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the average particle size is within the above range, there are no disadvantages, the compositional uneven distribution among the toners is reduced, the dispersion in the toner is improved, and the variation in performance and reliability is advantageous. . The volume average particle diameter is measured using, for example, a Coulter counter method, a photon correlation method, a laser diffraction / scattering method, a white light polarization method, or the like.

  The dispersion medium in the dispersion is preferably an aqueous medium. Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together. In addition, it is desirable to add and mix a surfactant in the aqueous medium. Although it does not specifically limit as surfactant, For example, anionic surfactants, such as sulfate ester type, sulfonate type, phosphate ester type, soap type; amine salt type, quaternary ammonium salt type, etc. Nonionic surfactants such as polyethylene glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based, and the like. Among these, anionic surfactants and cationic surfactants are desirable. The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may use 2 or more types together.

  Specific examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium dodecylsulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate and the like. Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

For example, when a polyester resin is used as the binder resin, the polyester resin is preferably a polyester resin having a self-water dispersibility containing a functional group capable of becoming an anion type by neutralization. By neutralizing a part or all of the functional group capable of becoming an anionic type with a base, a stable aqueous dispersion is formed under the action of an aqueous medium.
In addition, examples of the functional group that can be converted into an anionic type by neutralization in the polyester resin include acidic groups such as a carboxyl group and a sulfone group. Examples of the neutralizing agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, Examples thereof include inorganic bases such as calcium hydroxide, sodium carbonate and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine.

  Further, when a polyester resin that does not disperse in water, that is, does not have self-water dispersibility, is used as the binder resin, an ionic surfactant, a polymer is added to the resin solution and / or an aqueous medium mixed therewith. It is desirable to add and disperse a polymer electrolyte such as an acid or a polymer base, heat it to the melting point or higher, and perform treatment using a homogenizer or a pressure discharge type disperser to which a strong shearing force is applied. By treating in this way, it is easily dispersed in particles of 0.5 μm or less. When the ionic surfactant or polymer electrolyte is used, the concentration in the aqueous medium is suitably 0.5 to 5% by mass. The mold release agent described later also applies to this.

  Furthermore, as a method of dispersing another polyester resin, a phase inversion emulsification method may be mentioned. In the phase inversion emulsification method, a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase), and the aqueous medium (W Phase), the resin is converted from W / O to O / W (so-called phase inversion) to form a discontinuous phase, and the resin is dispersed and stabilized in the form of particles in an aqueous medium. It is.

  Examples of the organic solvent used for this phase inversion emulsification include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, and tert. -Alcohols such as amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, isophorone, tetrahydrofuran , Ethers such as dimethyl ether, diethyl ether, dioxane, methyl acetate, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, vinegar -Sec-butyl, acetate-3-methoxybutyl, methyl propionate, ethyl propionate, butyl propionate, dimethyl oxalate, diethyl oxalate, dimethyl succinate, diethyl succinate, diethyl carbonate, dimethyl carbonate, Ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether , Diethylene glycol ethyl ether acetate Glycol derivatives such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetate, dipropylene glycol monobutyl ether, 3-methoxy-3-methylbutanol, 3-methoxy Examples include butanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate and the like. These solvents may be used singly or in combination of two or more.

  In the above phase inversion emulsification, when dispersing the binder resin in water, it is desirable to neutralize part or all of the carboxyl groups in the resin with a neutralizing agent, if necessary. Examples of the neutralizing agent include inorganic alkalis such as potassium hydroxide and sodium hydroxide, ammonia, monomethylamine, dimethylamine, triethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, dimethyl-n-propylamine, Amines such as monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-aminoethylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N, N-dimethylpropanolamine 1 type, or 2 or more types selected from these are used. By adding these neutralizing agents, the pH during emulsification is adjusted to neutral, and hydrolysis of the resulting polyester resin dispersion is suppressed.

  Also during the phase inversion emulsification, a dispersant may be added for the purpose of stabilizing the dispersed particles and preventing the thickening of the aqueous medium. Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate, sodium dodecylbenzenesulfonate, sodium octadecylsulfate, and oleic acid. Anionic surfactants such as sodium, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, zwitterionic surfactants such as lauryldimethylamine oxide, Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, etc. Surfactants such as on-surfactant, tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and inorganic compounds such as barium carbonate. These dispersants may be used alone or in combination of two or more. The dispersant is desirably added in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

  The emulsification temperature during phase inversion emulsification is preferably not higher than the boiling point of the organic solvent and not lower than the melting point (or transition point) of the release agent. If the emulsification temperature is not higher than the melting point or transition point of the release agent, a particle dispersion containing the release agent cannot be obtained. In addition, when emulsifying above the boiling point of the organic solvent, the emulsification may be performed with a pressure-sealed device.

As the colorant to be emulsified and dispersed as the raw material dispersion, the colorants described above are used.
As a method for dispersing the colorant, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and the colorant is not limited at all. If necessary, an aqueous dispersion of these colorants may be prepared using a surfactant, or an organic solvent dispersion of these colorants may be prepared using a dispersant. Hereinafter, such a colorant dispersion may be referred to as a “colored particle dispersion”. As the surfactant or dispersant used for dispersion, those according to the dispersant that can be used when dispersing the binder resin are used.

  The addition amount of the colorant is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, and further preferably 2 to 10% by mass with respect to the total amount of the resin. A content of 2 to 7% by mass is particularly desirable, but a larger amount is desirable as long as the image surface is not roughened after fixing. When the content of the colorant is increased, the thickness of the image can be reduced when an image having the same density is obtained, which is advantageous in terms of prevention of offset.

  These colorants may be added to the mixed solvent at the same time as other particle components, or may be divided and added in multiple stages.

As the release agent emulsified and dispersed as the raw material dispersion, the release agent described above is used.
The release agent is a homogenizer that is dispersed together with an ionic surfactant, etc. in water, heated above the melting point, and applied with a strong shearing force, according to the case of emulsifying and dispersing a polyester resin that does not have self-water dispersibility. Or a pressure discharge type disperser to adjust the dispersed particle diameter to 1 μm or less. As the dispersion medium in the release agent dispersion liquid, those according to the binder resin dispersion medium are used.

  As an apparatus for mixing and dispersing the binder resin and the colorant with an aqueous medium, for example, a homomixer (Special Machine Industries Co., Ltd.), Thrasher (Mitsui Mining Co., Ltd.), Cavitron (Eurotech Co., Ltd.), Examples thereof include continuous emulsion dispersers such as a microfluidizer (Mizuho Industrial Co., Ltd.), a Menton Gorin homogenizer (Gorin Inc.), a nanomizer (Nanomizer Inc.), a static mixer (Noritake Company), and the like.

  The content of the resin particles contained in the binder resin dispersion (resin particle dispersion) in the emulsification step, the content of the colorant in the colorant dispersion (colored particle dispersion), and the release agent dispersion The content of the release agent in (release agent particle dispersion) is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass. When the content is outside the above range, the particle size distribution may be widened and the characteristics may be deteriorated.

Further, depending on the purpose, other components such as the internal additive, the charge control agent, and the inorganic powder described above may be dispersed in the binder resin dispersion.
The charge control agent is preferably made of a material that is difficult to dissolve in water in terms of controlling ionic strength that affects the stability of the aggregation process and the fusion process and reducing wastewater contamination.

  The average particle diameter of the other components is desirably 1 μm or less, and more preferably 0.01 to 0.5 μm. When the average diameter exceeds 1 μm, the particle size distribution of the finally obtained toner is broadened, and free particles are generated, which tends to cause deterioration in performance and reliability. On the other hand, when the average particle diameter is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toner is good, and the variation in performance and reliability is advantageous.

(Aggregation process)
In the agglomeration step, the respective dispersions of resin particles, colorants and the like obtained in the emulsification step are mixed (this mixture is referred to as “raw material dispersion”), and heated to a temperature of 50 ° C. or less, for example. Aggregated particles are formed by aggregating the dispersed particles.

  Moreover, before performing an aggregation process, it is desirable to add a high acid value dispersing agent as an additive to the resin particle dispersion (polyester resin dispersion) obtained by the emulsification process. Examples of the high acid value dispersant include copolymer resins having a carboxyl group and salts thereof. By adding a high acid value dispersant and adsorbing it on the emulsified particle surface of the polyester resin, the surface of the emulsified particle is maintained in a state where the electrostatic repulsion force is sufficiently applied, so that rapid particle growth in the aggregation process is suppressed. Is done. In addition, since the electrostatic repulsion effect derived from these anionic dissociation groups acts also in the fusion step described later, the adhesion between the aggregated particles can be sufficiently prevented, and the granulation can be controlled stably. Furthermore, the method of adding the high acid value dispersant after completion of the aggregation can sufficiently prevent the aggregation particles from adhering in the fusing step, and the granulation is stably controlled.

  Agglomerated particles are formed by increasing the initial agglomeration by acidifying the pH of the raw material dispersion, adding a flocculant at room temperature (20 to 25 ° C, the same applies below) with high-speed stirring using a rotary shearing homogenizer. This is done by dispersing the flocculant in the viscous raw material dispersion. The pH is preferably in the range of 2 to 6, and more preferably in the range of 3 to 6.

  As described above, the acidic pH range is suitable for the formation of aggregated particles. For example, the polyester resin resin particle dispersion obtained by the phase inversion emulsification method has a pH in the range of 7 to 8, When a colorant dispersion or a release agent dispersion having a pH of 3 to 5 is mixed or adjusted to the above pH for aggregation, the balance of polarity is lost and slow aggregation occurs. Therefore, when the pH of the resin particle dispersion of the polyester resin is on the alkali side, a surfactant and a high acid value dispersant were added in advance at room temperature to familiarize the surfactant and dispersant on the resin particle surface. Thereafter, it is desirable to adjust the pH by mixing a colorant and a release agent.

  As the aggregating agent used in the aggregating step, a surfactant having a polarity opposite to that of the surfactant used for preparing the dispersion, an inorganic metal salt, or a divalent or higher-valent metal complex is preferably used. In particular, when a metal complex is used, the amount of the surfactant used can be reduced and charging characteristics are improved, which is desirable.

  Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers. Of these, aluminum salts and polymers thereof are particularly preferred. In order to obtain a sharper particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. The inorganic metal salt polymer is more suitable.

  In the aggregation step, in order to suppress rapid aggregation due to heating, the pH may be adjusted while stirring and mixing at room temperature, and a dispersion stabilizer may be added as necessary.

  In the final toner, it is desirable to add a coating step after the aggregation step in order to further improve the chargeability and powder flowability. In this coating step, the same or different resin particles as the binder resin are adhered to the surface of the above-mentioned aggregated particles to form adhered particles to form a coating layer (that is, a toner having a core-shell structure). . The formation can be performed by additionally adding a dispersion liquid containing a binder resin or other resin particles to the dispersion liquid in which the aggregated particles are formed in the aggregation process. It may be added. As the binder resin (resin particles) used for forming the coating layer, those according to the aforementioned binder resin (that is, the core layer binder resin) are used. Also in the coating process, the pH and surfactant are selected according to the agglomeration process according to the resin used, and the coated aggregated particles are obtained with care so as not to adhere to the surface of the aggregated particles. This coating step is also effective in guiding raw material particles that have not been taken into the aggregated particles in the aggregation step.

(Fusion process)
In the fusion step, the agglomeration is stopped by advancing the aggregation by adjusting the pH of the suspension of the aggregated particles (or attached particles) to a range of 6.0 to 7.5 under stirring according to the aggregation step. The aggregated particles (or adhered particles) are fused by heating at a temperature equal to or higher than the melting point of the binder resin. Although depending on the liquidity of the dispersion containing the aggregated particles (raw material dispersion), if the pH at which aggregation is stopped is not appropriate, the aggregated particles will be dispersed during the temperature rising process for fusing, resulting in a high yield. In some cases, the agglomeration becomes worse, or condensation cannot be stopped, and the particle size growth further proceeds, resulting in a large particle size.

  When the crystalline polyester resin is contained in the aggregated particles, the heating temperature at the time of fusing is not a problem as long as the temperature is not lower than the melting point, and if not included, the temperature is not lower than the glass transition point of the amorphous resin. The heating time may be as long as desired fusion is performed, and may be performed for about 0.5 to 3 hours. When heated for a longer time, the release agent contained in the aggregated particles is likely to be exposed on the toner surface. Therefore, although it is effective for fixing properties, it is undesirable to heat for a long time because it adversely affects the storage stability of the toner.

  In the fusion step, a crosslinking reaction may be performed when the binder resin is heated to a melting point or a glass transition point or higher, or after the fusion is completed. Further, a crosslinking reaction may be performed simultaneously with the fusion. When the crosslinking reaction is performed, for example, an unsaturated crystalline polyester resin obtained by copolymerizing a double bond component as a binder resin is used, and a radical reaction is caused in the resin to introduce a crosslinked structure. At this time, the following polymerization initiator is preferably used.

Examples of the polymerization initiator include t-butyl peroxy-2-ethylhexanoate, cumyl perpivalate, t-butyl peroxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t. -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-bis (t-butylperoxy) -3,3,5-trimethyl Cyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,4-bis (t-butylperoxycarbo) Nyl) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, , 3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylper) Oxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-t-butyldiperoxyisophthalate, 2,2-bis (4,4-di-t-butylperoxy) (Cyclohexyl) propane, di-t-butylperoxy α-methylsuccinate, di-t-butylperoxydimethylglutarate, di-t-butylperoxyhexahydroterephthalate , Di-t-butylperoxyazelate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, diethylene glycol-bis (t-butylperoxycarbonate), di-t-butyl Peroxytrimethyladipate, tris (t-butylperoxy) triazine, vinyltris (t-butylperoxy) silane, 2,2′-azobis (2-methylpropionamidine dihydrochloride), 2,2′-azobis [N -(2-carboxyethyl) -2-methylpropionamidine], 4,4′-azobis (4-cyanovaleric acid) and the like.
These polymerization initiators may be used alone or in combination of two or more. The amount and type of the polymerization initiator are selected depending on the amount of unsaturated sites in the binder resin and the type and amount of the coexisting colorant.

  The polymerization initiator may be previously mixed with the binder resin before the emulsification step, or may be incorporated into the aggregated particles in the aggregation step. Further, it may be introduced after the fusion step or after the fusion step. When the polymerization initiator is introduced during the aggregation process, the coating process, the fusion process, or after the fusion process, a solution in which the polymerization initiator is dissolved or emulsified is added to the resin particle dispersion or the like. These polymerization initiators may be added with known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for the purpose of controlling the degree of polymerization.

The fused particles obtained by fusing become toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is desirable to perform sufficient cleaning in the cleaning process.
In the drying process, methods such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, and a flash jet method are employed.

The toner particles after drying preferably have a water content of 1.5% by mass or less, more preferably 1.0% by mass or less after standing for 3 days in an environment of 28 ° C./85% RH. . When the moisture content is in the above range, the charge amount of the toner does not decrease under high humidity conditions, and the charging characteristics of the toner due to changes in humidity are stabilized.
The toner moisture content was measured by leaving 2 g of toner in an environment of 28 ° C. and humidity 85% RH for 24 hours, and then evaporating water at a heating temperature of 150 ° C. using a halogen moisture analyzer (manufactured by METTLER TOLEDO). This is done by measuring the quantity.

  To the toner particles granulated through the drying step as described above, various known external additives such as the inorganic particles and organic particles described above may be added as other components depending on the purpose.

-Toner softening temperature-
In the present invention, the softening temperature of the toner means a temperature obtained by the following method.
Specifically, using an elevated flow tester [CFT-500] (manufactured by Shimadzu Corporation), the diameter of the pore of the die is 1 mm, the pressure is 10 kg / cm ² , and the heating rate is 3 ° C./min. The sample No. ³ is melted and discharged, and the temperature corresponding to 1/2 of the height from the start point to the end point is defined as the softening temperature of the toner.

  The specific softening temperature (Tm [0]) of the contact toner image forming toner is preferably 110 ° C. or lower and more preferably 100 ° C. or lower from the viewpoint of increasing the heat softening effect in the deinking step. Further, Tm [0] is desirably 80 ° C. or higher from the viewpoint of suppressing deterioration of deinking property due to immersion of the toner melt to the deep part of the image medium at the time of fixing and suppressing toner aggregation. Therefore, Tm [0] is preferably 80 ° C. or higher and 110 ° C. or lower, more preferably 80 ° C. or higher and 100 ° C. or lower, and further preferably 85 ° C. or higher and 95 ° C. or lower.

  Further, the softening temperature (Tm [1]) of the toner for forming the outermost toner image is desirably 90 ° C. or higher from the viewpoint of suppressing the winding and offset of the paper around the fixing machine in the fixing process and improving the reliability. 95 ° C. or higher is more desirable. Further, Tm [1] is desirably 120 ° C. or less, and more desirably 115 ° C. or less, from the viewpoint of keeping the fixing temperature low. Therefore, Tm [1] is preferably 90 ° C. or higher and 120 ° C. or lower, more preferably 95 ° C. or higher and 115 ° C. or lower, and further preferably 100 ° C. or higher and 110 ° C. or lower.

  Further, when a non-contact toner image other than the outermost toner image is formed, the softening temperature (Tm [2]) of the non-contact toner image forming toner other than the outermost toner image forming toner is also the above Tm [1]. A similar range is desirable.

As described above, the relationship between Tm [0] and Tm [1] of the toner used in the embodiment is Tm [0] <Tm [1], and a non-contact toner image other than the outermost toner image is formed. In this case, the relationship of Tm [0] <Tm [2] is also satisfied.
When a non-contact toner image other than the outermost toner image is formed, it is desirable that the relationship of Tm [0] <Tm [2] <Tm [1] is satisfied as described above.

  Further, the difference between Tm [0] and Tm [1] (that is, Tm [1] −Tm [0] value) is 5 ° C. or more and 15 ° C. or less from the viewpoint of coexistence of deinking property and high temperature offset suppression. Is desirable, 6 to 12 ° C. is more desirable, and 7 to 10 ° C. is more desirable.

  As a method for controlling the softening temperature of the toner, for example, a method of controlling by the degree of polymerization (molecular weight) of the binder resin, a method of controlling by the degree of crosslinking of the binder resin, and a method of controlling by adding inorganic particles in the toner And a method of controlling by the concentration of aluminum ions in the toner.

  Note that the softening temperature of the toner image formed on the recording medium in the printed material is the same as the softening temperature of the toner used to form the toner image, and thus the description thereof is omitted.

-Other toner characteristics-
The L * value in the CIE 1976 (L * a * b *) color system of the contact toner image forming toner is desirably larger than the L * value of the non-contact toner image forming toner.
The contact toner image forming toner is most preferably free from a colorant, and more preferably colorless and transparent, from the viewpoint of suppressing coloring by residual toner after deinking.

  Specifically, the L * value of the contact toner image forming toner is desirably 85 or more and less than 94, and more desirably 90 or more and less than 94, from the viewpoint of suppressing coloring by the residual toner after the deinking process.

The L * value of the toner is controlled by the type and content of the colorant contained in the toner and the dispersion state thereof.
The L * value, b * value, and a * value of the toner are determined by measuring using a spectrocolorimeter (trade name: X-Rite 939, manufactured by X-Rite).

  The volume average particle diameter of the toner is preferably in the range of 1 to 20 μm, and more preferably in the range of 2 to 8 μm. The number average particle size is preferably in the range of 1 to 20 μm, and more preferably in the range of 2 to 8 μm.

  The volume average particle diameter and the number average particle diameter are measured by measuring with a 50 μm aperture diameter using a Coulter Multisizer II type (manufactured by Beckman-Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

  For the divided particle size range (channel), a cumulative distribution is drawn from the small diameter side with respect to the divided particle size range (channel), and the particle size at 50% accumulation is defined as the volume average particle size or number average particle size. .

-Developer-
Examples of the developer used in the embodiment include a one-component developer using the toner as it is, and a two-component developer using the toner and a carrier mixed.

  The carrier that can be used for the two-component developer is not particularly limited, and a known carrier may be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins, and the like.

  Examples of the conductive material include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black, but are not limited thereto. It is not something.

  Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is desirable. The volume average particle size of the core material of the carrier is generally in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 100 μm.

  In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution prepared by dissolving the coating resin and, if necessary, various additives in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the carrier core material, and the carrier core material is fluidized air. A fluidized bed method in which the coating layer forming solution is sprayed in a state of being suspended by the above, a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed.

  The mixing ratio (mass ratio) of toner and carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and in the range of 3: 100 to 20: 100. More desirable.

<Recording medium>
Hereinafter, the recording medium used in the above embodiment will be described in detail.
Examples of the recording medium include commonly used recording paper such as plain paper and general printing paper. Specifically, for example, a material containing pulp fiber (and filler as necessary) as a main component may be used. The recording medium used in the above embodiment includes, for example, a medium in which pulp fibers are exposed on a surface on which a toner image is formed.

  The pulp fiber is a chemical pulp, specifically, hardwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood bleached kraft pulp, softwood unbleached kraft pulp, hardwood bleached sulfite pulp, hardwood unbleached sulfite pulp, softwood bleached sulfite. In addition to pulp, softwood unbleached sulfite pulp, and the like, pulp made by chemically treating wood and fiber raw materials such as cotton, hemp, and leather are desirable.

  In addition, ground wood pulp that mechanically pulps wood and chips, chemimechanical pulp mechanically pulped after chemicals are soaked into wood and chips, and pulping with refiner after chips are softened slightly Also used are thermomechanical pulps and chemithermomechanical pulps that are characterized by high yields. These may be used only with virgin pulp, or waste paper pulp may be added as necessary.

  The virgin pulp is bleached mainly using ozone / hydrogen peroxide or the like without using chlorine gas and using chlorine dioxide (Elementary Chlorine Free: ECF) or without using any chlorine compound. What was bleach-processed by the method (Total Chlorine Free: TCF) is desirable. In addition, as raw materials of the waste paper pulp, unprinted waste paper such as cuts, damaged paper, widened white, special white, medium white, white loss, etc. generated in bookbinding, printing factories, cutting offices, etc .; printing and copying High-quality printed paper such as high-quality paper, high-quality coated paper, etc .; water-based ink, oil-based ink, old paper written with pencils; printed high-quality paper, high-quality coated paper, medium-quality paper, medium-quality coated paper Newspaper waste paper including flyers; waste paper such as medium-quality paper, medium-quality coated paper, and renewed paper, and the like may be used as appropriate.

The waste paper pulp is preferably one obtained by treating the above-mentioned raw material with at least one of ozone bleaching treatment and hydrogen peroxide bleaching treatment. The ozone bleaching process has an action of decomposing fluorescent dyes or the like usually contained in fine paper, and the hydrogen peroxide bleaching process has an action of preventing yellowing due to alkali used in the deinking process.
From the viewpoint of increasing the whiteness, it is desirable that the ratio of the used paper pulp obtained by the bleaching treatment is 50 to 100% by mass. Further, from the viewpoint of resource reuse, it is more preferable that the ratio of the waste paper pulp is 70 to 100% by mass.

  By combining the two treatments of ozone bleaching or hydrogen peroxide bleaching, the waste paper pulp not only facilitates deinking of the waste paper, but also improves the whiteness of the pulp. In addition, since there is an action of decomposing / removing residual chlorine compounds in the pulp, a great effect can be obtained in reducing the content of organic halogen compounds in used paper using chlorine bleached pulp.

In addition to the pulp fiber, a filler may be added to the recording paper as necessary in order to adjust the opacity, whiteness and surface properties. When it is desired to reduce the halogen content, it is desirable to use a filler that does not contain halogen.
As the filler, heavy calcium carbonate, light calcium carbonate, chalk, kaolin, calcined clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, aluminum silicate, calcium silicate, magnesium silicate, Synthetic silica, aluminum hydroxide, alumina, sericite, white carbon, saponite, calcium montmorillonite, sodium montmorillonite, bentonite and other inorganic pigments, acrylic plastic pigments, polyethylene, chitosan particles, cellulose particles, polyamino acid particles, urea Examples thereof include organic pigments such as resins.

Further, when used paper pulp is added to the recording paper, it is necessary to estimate the ash contained in the used paper pulp raw material in advance and adjust the addition amount.
The blending amount of the filling amount is not particularly limited, but is preferably 1 to 80 parts by weight and more preferably 1 to 50 parts by weight with respect to 100 parts by weight of the pulp fiber.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

[Measuring method]
<Measurement method of toner softening temperature>
Using an elevated flow tester [CFT-500] (manufactured by Shimadzu Corporation), a 1 cm ³ sample was melted under the conditions of a 1 mm die pore diameter, a pressure of 10 kg / cm ² , and a heating rate of 3 ° C./min. The temperature corresponding to ½ of the height from the outflow start point to the end point is defined as the toner softening temperature (Tm).

<Measuring method of glass transition temperature and melting point>
The glass transition temperature and melting point were measured according to JIS 7121-1987 using a differential scanning calorimeter (manufactured by Mac Science: DSC3110, thermal analysis system 001). The melting point of a mixture of indium and zinc was used for temperature correction of the detection part of this apparatus, and the heat of fusion of indium was used for correction of heat quantity. The sample was put in an aluminum pan, an aluminum pan containing the sample and an empty aluminum pan for control were set, and the measurement was performed at a heating rate of 10 ° C./min.
About melting | fusing point, it was set as melting | fusing point with the temperature of the peak of the largest endothermic peak among the endothermic peaks of the DSC curve obtained by measurement.
Moreover, about the glass transition temperature, it was set as the glass transition temperature with the temperature of the intersection of the extended line of the base line in the endothermic part of the DSC curve obtained by the measurement, and the rising line.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) (polystyrene conversion) of the polyester resin was measured using GPC (Tosoh Co., Ltd .: HLC-8120 made). The column used was Tosoh TSKgel SuperHM-M (15 cm), and the GPC spectrum was measured with a THF solvent. The molecular weight of the polyester resin was calculated using a molecular weight calibration curve created with a monodisperse polystyrene standard sample.

<Measurement method of toner volume average particle diameter>
The volume average particle diameter of the toner was measured using a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) measuring device. As the electrolytic solution, ISOTON-II (manufactured by Beckman-Coulter) was used.

  As a measurement method, 0.5 mg of a measurement sample was added to 2 ml of a 5% aqueous solution of a surfactant (sodium dodecylbenzenesulfonate) as a dispersant, and this was added to 100 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute. Using the Coulter Multisizer-II type aperture with an aperture diameter of 100 μm, the particle size is 2.0 to 60 μm. The particle size distribution of particles in the range was measured. The number of particles measured is 50,000.

  In the measured particle size distribution, a cumulative distribution was drawn from the small diameter side with respect to the divided particle size range (channel), and the particle size at 50% cumulative was defined as the volume average particle size.

<Measuring method of average particle diameter of resin particles / release agent particles / pigment particles>
Using a laser diffraction particle size distribution measuring device (LA-700: manufactured by Horiba, Ltd.), the volume average particle size of resin particles, release agent particles, and pigment particles was measured.

  As a measuring method, the sample in the state of dispersion is adjusted so as to have a solid content of 2 g, and ion exchange water is added thereto to make 40 ml. This was added to the cell until the appropriate concentration was reached, waited for 2 minutes, and measured when the concentration in the cell became stable.

  The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

  When measuring powder, 2 g of a measurement sample is added to 50 ml of a 5% aqueous solution of a surfactant (sodium dodecylbenzenesulfonate), and dispersed for 2 minutes with an ultrasonic disperser (1,000 Hz). A sample was prepared and measured by the same method as the above-mentioned dispersion.

[Production of toner]
<Production of cyan toner C1> (softening temperature 104 ° C.)
(Amorphous polyester resin particle dispersion (1))
-310 parts of bisphenol A propylene oxide 2 mol adduct-116 parts of terephthalic acid-12 parts of fumaric acid-54 parts of dodecenyl succinic acid-0.05 part of Ti (OBu) ₄ After the above raw materials were put into a heat-dried three-necked flask, The air in the container was depressurized by a depressurization operation, and was further brought into an inert atmosphere with nitrogen gas, and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 240 ° C. while distilling off the water produced in the reaction system by vacuum distillation. Further, the dehydration condensation reaction was continued at 240 ° C. for 2 hours. When the mixture became viscous, the molecular weight was confirmed by GPC. ) The amorphous polyester resin (1) was amorphous, the glass transition point was 60 ° C., and the acid value was 14 mgKOH / g.

  Next, 100 parts of this amorphous polyester resin (1), 50 parts of ethyl acetate, 25 parts of isopropyl alcohol, and 5 parts of a 10% by mass aqueous ammonia solution were placed in a separable flask, thoroughly mixed and dissolved. While heating and stirring at ° C., ion-exchanged water was added dropwise using a liquid feed pump at a liquid feed speed of 8 g / min. After the liquid became cloudy, the liquid feeding speed was increased to 25 g / min to cause phase inversion, and dropping was stopped when the liquid feeding amount reached 135 parts. Thereafter, the solvent was removed under reduced pressure to obtain an amorphous polyester resin particle dispersion (1). The obtained polyester resin particles had a volume average particle size of 132 nm and the polyester resin particles had a solid content concentration of 38%.

(Amorphous polyester resin particle dispersion (2))
The amorphous polyester resin is the same as the amorphous polyester resin (1) except that the vacuum distillation is stopped when the weight average molecular weight is 12,000 instead of stopping the vacuum distillation when the weight average molecular weight is 12,000. (2) was obtained.

(Amorphous polyester resin particle dispersion (3))
The amorphous polyester resin is the same as the amorphous polyester resin (1) except that the vacuum distillation is stopped when the weight average molecular weight reaches 22,000 instead of stopping the vacuum distillation when the weight average molecular weight reaches 26000. (3) was obtained.

(Amorphous polyester resin particle dispersion (4))
The amorphous polyester resin is the same as the amorphous polyester resin (1), except that the vacuum distillation is stopped when the weight average molecular weight reaches 20,000, but the vacuum distillation is stopped when the weight average molecular weight reaches 10,000. (4) was obtained.

(Amorphous polyester resin particle dispersion (5))
The amorphous polyester resin is the same as the amorphous polyester resin (1) except that the vacuum distillation is stopped when the weight average molecular weight reaches 2,000, instead of stopping the vacuum distillation when the weight average molecular weight reaches 9000. (5) was obtained.

(Crystalline polyester resin dispersion)
In a heat-dried three-necked flask, 230 parts of 1,10-dodecanedioic acid, 160 parts of 1,9-nonanediol, and 0.2 part of dibutyltin oxide as a catalyst were added, and then the air in the three-necked flask was removed by depressurization. The reaction was allowed to proceed under an inert atmosphere by replacing with nitrogen at 180 ° C. for 5 hours by mechanical stirring and refluxing. During the reaction, water produced in the reaction system was distilled off. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and when the mixture became viscous after stirring for 2 hours, the molecular weight was confirmed by GPC. When the weight average molecular weight reached 29000, the distillation under reduced pressure was stopped and the crystals A functional polyester resin was obtained. The melting point of the crystalline polyester resin was 73 ° C., and the acid value was 12 mgKOH / g.

  Next, 100 parts of this crystalline polyester resin, 35 parts of ethyl acetate, and 35 parts of isopropyl alcohol are placed in a separable flask and thoroughly mixed and dissolved at 75 ° C. Then, 5.5 parts of a 10% aqueous ammonia solution is added dropwise. did. The heating temperature is lowered to 60 ° C., and ion-exchanged water is added dropwise with stirring using a liquid feed pump at a liquid feed speed of 6 g / min. After the liquid becomes cloudy, the liquid feed speed is increased to 25 g / min. When the amount reached 400 parts, dropping of ion-exchanged water was stopped. Thereafter, the solvent was removed under reduced pressure to obtain a crystalline polyester resin dispersion. The obtained crystalline polyester resin particles had a volume average particle size of 136 nm and the polyester resin particles had a solid content concentration of 11.5%.

(Colorant dispersion)
・ 100 parts of cyan pigment (Daiichi Seika Co., Ltd., CI Pigment Blue 15: 3, (copper phthalocyanine)) 15 parts of anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) Disperse the colorant by mixing 900 parts or more of water, dissolving, and dispersing for 1 hour using a high-pressure impact disperser Ultimateizer (manufactured by Sugino Machine Co., Ltd., HJP30006) to disperse the colorant (cyan pigment). A liquid was prepared. The average particle diameter of the colorant (cyan pigment) in the colorant dispersion was 0.13 μm, and the colorant particle concentration was 25%.

(Release agent dispersion)
-Ester wax (WEP5, manufactured by NOF Corporation) 50 parts-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) 5 parts-Ion-exchanged water 200 parts After dispersing using a homogenizer (IKA: Ultra Tarrax T50), the dispersion is dispersed with a Manton Gorin high-pressure homogenizer (Gorin) to disperse a release agent having an average particle size of 0.24 μm. A release agent dispersion (release agent concentration: 23%) was prepared.

(Manufacture of toner)
Amorphous polyester resin particle dispersion (1) 302.6 parts Crystalline polyester resin dispersion 30.0 parts Colorant dispersion 48.0 parts Anionic surfactant (dowfax 2A1, 20% aqueous solution) 11 .5 parts / release agent dispersion 80.2 parts Amorphous polyester resin particle dispersion (1), crystalline polyester resin dispersion among the above raw materials in a polymerization kettle equipped with a pH meter, stirring blades, and thermometer The liquid, the anionic surfactant, and 631 parts of ion-exchanged water were added, and the surfactant was mixed with the amorphous polyester resin particle dispersion (1) while stirring at 200 rpm for 15 minutes. Subsequently, the colorant dispersion and the release agent dispersion were added to and mixed with this, and then a 0.3 M nitric acid aqueous solution was added to the raw material mixture to adjust the pH to 2.7. Subsequently, 100 parts of 10% aqueous solution of aluminum sulfate was added dropwise as a flocculant while applying a shearing force at 1000 rpm with Ultraturrax (manufactured by IKA Japan). In addition, since the viscosity of the raw material mixture increases during the dropping of the flocculant, the dropping speed was reduced when the viscosity increased, so that the flocculant was not biased to one place. When the dropping of the flocculant was completed, the rotational speed was further increased to 6000 rpm and the mixture was stirred for 5 minutes to sufficiently mix the flocculant and the raw material mixture.

  Next, the raw material mixture was stirred at 550 to 650 rpm while being heated to 30 ° C. with a mantle heater. After stirring for 60 minutes, it was confirmed that the primary particle diameter was stably formed using a Coulter Multisizer II type (aperture diameter: 50 μm, manufactured by Beckman-Coulter). The temperature was raised to 45 ° C at a rate of 1 minute. The growth of the agglomerated particles is confirmed at any time using a Coulter Multisizer type II, and the agglomeration temperature and the number of rotations of stirring are changed depending on the agglomeration speed.

  On the other hand, 75.4 parts of ion-exchanged water and 5.6 parts of an anionic surfactant (dowfax 2A1, 20% aqueous solution) were added to 147.4 parts of the amorphous polyester resin particle dispersion (1) for coating aggregated particles. In addition, a coating resin particle dispersion (1) prepared in advance and adjusted to pH 2.7 was prepared. When the aggregated particles grew to 5.0 μm in the aggregation step, the coating resin particle dispersion (1) was added and held for 10 minutes with stirring. Thereafter, in order to stop the growth of the coated aggregated particles (adhered particles), 16.7 parts of an EDTA aqueous solution (manufactured by Killes Co., Ltd., Kirest 40 diluted to 12% concentration with ion-exchanged water) and 1M hydroxylated water Sodium aqueous solution was added in order, and the pH of the raw material mixture was controlled to 6.5. Subsequently, in order to fuse the aggregated particles, the temperature was raised to 85 ° C. at a temperature raising rate of 1 ° C./min while adjusting the pH to 6.5. After confirming that the aggregated particles were fused with an optical microscope, ice water was injected and rapidly cooled at a cooling rate of 100 ° C./min.

  Next, the pH of the slurry after cooling the obtained particles with 1N aqueous sodium hydroxide solution was adjusted to 9.0, stirred for 20 minutes, and sieved once with a 20 μm mesh. Thereafter, approximately 10 times the amount of warm water (50 ° C.) was added to the solid content, and the mixture was stirred for 20 minutes while adjusting the pH to 9.0 again, washed with warm alkali, and once filtered. Further, the solid content remaining on the filter paper is dispersed in the slurry and washed three times with 40 ° C. warm water, and further washed with acid at 40 ° C. while adding a 0.3N nitric acid aqueous solution to the slurry to 4.0. went. Then, finally, the mixture was washed with stirring in warm ion-exchanged water at 40 ° C. and dried to obtain toner base particles (A1) having a volume average particle diameter of 6.4 μm.

To the toner base particles (A1) obtained above, silica fine powder (particle diameter: 50 nm) and titania fine powder (particle diameter: 40 nm) as external additives were added in an amount of 0.9 parts with respect to 100 parts of the toner base particles. And 0.6 part were added and mixed with a Henschel mixer to obtain cyan toner C1.
Table 1 shows the softening temperature and L * value of the cyan toner C1.

<Production of cyan toner C2> (softening temperature 95 ° C.)
In order to adjust the softening temperature of the toner, the cyan toner is the same as the cyan toner C1 except that the amorphous polyester resin particle dispersion (2) is used instead of the amorphous polyester resin particle dispersion (1). C2 was obtained.
Table 1 shows the softening temperature and L * value of cyan toner C2.

<Production of cyan toner C3> (softening temperature 115 ° C.)
In order to adjust the softening temperature of the toner, instead of the crystalline polyester resin dispersion, an amorphous polyester resin dispersion (1) weighed so as to have the same solid content was used. Similarly, cyan toner C3 was obtained.
Table 1 shows the softening temperature and L * value of cyan toner C3.

<Production of magenta toner M1> (softening temperature 102 ° C.)
A magenta toner M1 was obtained in the same manner as the cyan toner C1, except that 100 parts of a magenta pigment (CI Pigment Red 122, manufactured by Clariant) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the magenta toner M1.

<Production of magenta toner M2> (softening temperature 95 ° C.)
A magenta toner M2 was obtained in the same manner as the cyan toner C2, except that 100 parts of a magenta pigment (Cligant, CI Pigment Red 122) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the magenta toner M2.

<Production of magenta toner M3> (softening temperature 115 ° C.)
A magenta toner M3 was obtained in the same manner as the cyan toner C3 except that 100 parts of a magenta pigment (CI Pigment Red 122, manufactured by Clariant) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the magenta toner M3.

<Production of yellow toner Y1> (softening temperature 101 ° C.)
A yellow toner Y1 was obtained in the same manner as the cyan toner C1, except that 120 parts of a yellow pigment (Clariant, CI Pigment Yellow 74) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the yellow toner Y1.

<Production of yellow toner Y2> (softening temperature 95 ° C.)
A yellow toner Y2 was obtained in the same manner as the cyan toner C2, except that 120 parts of a yellow pigment (Clariant, CI Pigment Yellow 74) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the yellow toner Y2.

<Production of yellow toner Y3> (softening temperature 115 ° C.)
A yellow toner Y3 was obtained in the same manner as the cyan toner C3 except that 120 parts of a yellow pigment (Clariant, CI Pigment Yellow 74) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the yellow toner Y3.

<Production of black toner K1> (softening temperature 102 ° C.)
Black toner K1 was obtained in the same manner as cyan toner C1, except that 100 parts of black pigment (Cabot, Regal 330) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the black toner K1.

<Production of black toner K2> (softening temperature 95 ° C.)
A black toner K2 was obtained in the same manner as the cyan toner C2, except that 100 parts of a black pigment (Cabot, Regal 330) was used instead of the cyan pigment used in the colorant dispersion.
Table 1 shows the softening temperature and L * value of the black toner K2.

<Production of black toner K3> (softening temperature 120 ° C.)
In order to adjust the softening temperature of the toner, the amorphous polyester resin particle dispersion (3) is used instead of the amorphous polyester resin particle dispersion (1), and the amount of EDTA aqueous solution added in the aggregation stopping step is 5 parts. A black toner K3 was obtained in the same manner as the black toner K1, except that the pH of the raw material mixture after the addition of the EDTA aqueous solution and the sodium hydroxide aqueous solution was controlled to 8.
Table 1 shows the softening temperature and L * value of the black toner K3.

<Production of non-colored toner S1> (softening temperature 95 ° C.)
Non-colored toner S1 was obtained in the same manner as cyan toner C2, except that the cyan pigment used in the colorant dispersion was not used.
Table 1 shows the softening temperature and L * value of the non-colored toner S1.

<Production of non-colored toner S2> (softening temperature 80 ° C.)
In order to adjust the softening temperature of the toner, the amorphous polyester resin particle dispersion (4) is used instead of the amorphous polyester resin particle dispersion (1), and the amount of the release agent dispersion added is 100 parts. A non-colored toner S2 was obtained in the same manner as the non-colored toner S1, except that the amount of the crystalline polyester resin dispersion added was 20 parts.
Table 1 shows the softening temperature and L * value of the non-colored toner S2.

<Production of non-colored toner S3> (softening temperature 110 ° C.)
Non-colored toner S3 was obtained in the same manner as cyan toner C3, except that no cyan pigment was used.
Table 1 shows the softening temperature and L * value of the non-colored toner S3.
<Production of non-colored toner S4> (softening temperature 75 ° C.)
In order to adjust the softening temperature of the toner, the amorphous polyester resin particle dispersion (5) is used instead of the amorphous polyester resin particle dispersion (1), and the amount of the release agent dispersion added is 100 parts. A non-colored toner S4 was obtained in the same manner as the non-colored toner S1, except that the amount of the crystalline polyester resin dispersion added was 20 parts.
Table 1 shows the softening temperature and L * value of the non-colored toner S4.

[Manufacture of developer]
15 parts of a resin copolymerized with styrene / methyl methacrylate / isobutyl methacrylate (mass ratio of 30/60/10) (manufactured by Soken Chemical Co., Ltd., molecular weight: 82000) is dissolved in 500 parts of toluene, and ferrite particles (volume average particle size) are obtained. (Diameter: 35 μm) 100 parts were added and distilled under reduced pressure in a kneader to prepare a resin-covered carrier.
36 g of the toner and 414 g of the carrier were placed in a 2 L V blender, stirred for 20 minutes, and then sieved with a mesh having a pore size of 212 μm to prepare a developer.

[Image formation]
<Example α1 , Reference Example α2, Example α3 to Example α5, Reference Example α6 to Reference Example α7, Comparative Example α1 to Comparative Example α3>
In the image forming apparatus (see FIG. 1) having the same configuration as that of the first embodiment, an image forming apparatus in which the toner cartridges 8S, 8Y, 8C, 8M, and 8K contain a developer containing toner shown in Table 2 is provided. Then, image formation was performed by the following method.
Specifically, the amount of each color toner applied per area is 4 [g / m ² ] (however, K color) on the surface of 75 g / m ² , 3 × 3 cm ² recording paper (C2 manufactured by Fuji Xerox Interfield). The toner alone was 4.8 [g / m ² ]), and 2 × 2 cm ² patches were laminated to form an unfixed image in which all types of toner images were laminated on the recording paper. Next, the fixing temperature is changed every 10 ° C. from 80 ° C. to 200 ° C., and an unfixed image is fixed on the recording paper at each fixing temperature, whereby all types of toner images are laminated and fixed on the recording paper. A printed product was produced.
In the produced printed matter, the contact toner image is a toner image formed by toner accommodated in the toner cartridge 8S, and the outermost toner image is a toner image formed by toner accommodated in the toner cartridge 8K. .

< Reference Example β1 to Reference Example β3>
In the image forming apparatus having the same configuration as that of the second reference example (see FIG. 3), the image forming apparatus in which the toner cartridges 8Y, 8C, 8M, and 8K contain the developer containing the toner shown in Table 3 is used. Images were formed by the following method.
Specifically, the amount of each color toner applied per area is 4 [g / m ² ] (however, K color) on the surface of 75 g / m ² , 3 × 3 cm ² recording paper (C2 manufactured by Fuji Xerox Interfield). The toner alone was 4.8 [g / m ² ]), and 2 × 2 cm ² patches were laminated to form an unfixed image in which all types of toner images were laminated on the recording paper. Next, the fixing temperature is changed every 10 ° C. from 80 ° C. to 200 ° C., and an unfixed image is fixed on the recording paper at each fixing temperature, whereby all types of toner images are laminated and fixed on the recording paper. A printed product was produced.
In the produced printed matter, the contact toner image is a toner image formed by toner accommodated in the toner cartridge 8Y, and the outermost toner image is a toner image formed by toner accommodated in the toner cartridge 8K. .

< Reference Example γ1>
In the image forming apparatus (see FIG. 4) having the same configuration as that of the third reference example , an image forming apparatus in which the toner cartridges 8Y, 8C, 8M, 8K, and 8S contain the developer containing toner shown in Table 4 is provided. Then, image formation was performed by the following method.
Specifically, the amount of each color toner applied per area is 4 [g / m ² ] (however, K color) on the surface of 75 g / m ² , 3 × 3 cm ² recording paper (C2 manufactured by Fuji Xerox Interfield). The toner alone was 4.8 [g / m ² ]), and 2 × 2 cm ² patches were laminated to form an unfixed image in which all types of toner images were laminated on the recording paper. Next, the fixing temperature is changed every 10 ° C. from 80 ° C. to 200 ° C., and an unfixed image is fixed on the recording paper at each fixing temperature, whereby all types of toner images are laminated and fixed on the recording paper. A printed product was produced.
In the produced printed matter, the contact toner image is a toner image formed by toner accommodated in the toner cartridge 8Y, and the outermost toner image is a toner image formed by toner accommodated in the toner cartridge 8S. .

< Reference Example δ1>
In the image forming apparatus having the same configuration as that of the fourth reference example (see FIG. 5), the toner cartridges 8B and 8K are filled with the developer containing the toner shown in Table 5, and the following method is used. Image formation was performed.
Specifically, the amount of each color toner applied per area is 4 [g / m ² ] (however, K color) on the surface of 75 g / m ² , 3 × 3 cm ² recording paper (C2 manufactured by Fuji Xerox Interfield). The toner alone was 4.8 [g / m ² ]), and 2 × 2 cm ² patches were laminated to form an unfixed image in which all types of toner images were laminated on the recording paper. Next, the fixing temperature is changed every 10 ° C. from 80 ° C. to 200 ° C., and an unfixed image is fixed on the recording paper at each fixing temperature, whereby all types of toner images are laminated and fixed on the recording paper. A printed product was produced.
In the produced printed matter, the contact toner image is a toner image formed by toner accommodated in the toner cartridge 8B, and the top surface toner image is a toner image formed by toner accommodated in the toner cartridge 8K. .

[Evaluation methods]
<Deinking evaluation>
Among the printed materials prepared above, a printed material prepared under the condition of a fixing temperature of 170 ° C. was used as a test paper, and an evaluation handsheet was prepared under the following conditions.

―Disaggregation―
An aqueous dispersion having the following composition is stirred and disaggregated at 50 ° C. for 20 minutes in a beaker.
・ Test paper 5.0%
・ NaOH 0.7%
・ Sodium silicate 3.0%
・ H ₂ O ₂ 1.0%
・ Deinking agent (“Liptor S2800” manufactured by Lion) 0.2%

―Dilution, dehydration, kneader treatment―
Next, water was added to the water dispersion after disaggregation to dilute to 5%, followed by centrifugal dehydration. Further, pulp (solid material obtained by centrifugal dehydration) 20%, sodium silicate 3.0%, NaOH 0. Add pulp, sodium silicate, etc. to 5% and disaggregate with a kneader (kneader treatment).

―Aging―
The kneader disaggregated material after the kneader treatment is aged at 50 ° C. for 2 hours.
―Flotation―
Water is added to the aged product after the aging to prepare a dispersion having a pulp concentration of 1%, fine bubbles are released into the dispersion for 7 minutes, and the toner in the liquid is adsorbed to the bubbles to float on the water surface. Separate toner and water.
-Washing-
The deinked pulp is washed twice with 1 liter of water each.
―Creation of handsheets for evaluation―
A paper sheet for evaluation (basis weight 75 g / m ² ) is prepared by a tapi sheet machine.

―Evaluation of deinking ability―
The deinking property was evaluated by measuring the five-point average brightness of the handsheet using a spectral densitometer (X-Rite 939) manufactured by X-Rite. Specifically, when L (0) is the lightness of the portion of the test paper where no toner is placed and L (1) is the lightness of the evaluation handsheet, | L (0) −L (1) | The value was obtained and the deinking property was evaluated. Further, the difference between the color tone of the test paper where no toner is placed and the color tone of the evaluation handsheet was evaluated visually. The evaluation criteria are as follows. The results are shown in Table 6.

(Evaluation criteria by brightness difference)
A: | L (0) -L (1) | ≦ 2
Δ: 2 <| L (0) −L (1) | ≦ 4
×: 4 <| L (0) −L (1) |

(Visual evaluation criteria)
A: There is almost no difference in color. Δ: A slight difference in color is recognized, but the allowable range. X: The difference in color is large.

<Evaluation of high temperature offset generation temperature and low temperature fixability>
The image of the printed matter produced in the above was visually observed, and the lowest fixing temperature at which image quality degradation started to occur due to the high temperature offset was defined as the high temperature offset generation temperature. If the high temperature offset generation temperature is 185 ° C. or higher, there is no practical problem. The results are shown in Table 6.
In addition, the image surface of the printed material produced above was folded to observe the degree of peeling of the image at the crease, and the lowest fixing temperature at which the image hardly peeled was set as the minimum fixing temperature, and the low-temperature fixing property was evaluated. . If the minimum fixing temperature is 150 ° C. or less, there is no practical problem. The results are shown in Table 6.

<Image preservation>
Among the printed matter produced in the above, two printed matter produced under the above-mentioned conditions of the minimum fixing temperature are superimposed on the image surface, and a load of 100 g / cm ² is applied in an environment of a temperature of 60 ° C. and a humidity of 85%. And left for 7 days. The superimposed images were peeled off, the images were fused between the printed materials, and whether or not there was transfer in the non-image area was visually observed and evaluated according to the following evaluation criteria. The evaluation criteria are as follows.
A: No problem in image storability △: Image transfer is hardly seen and is practically acceptable ×: Change is observed and practical use is not possible

As can be seen from Table 6, in Examples and Reference Examples , the deinking property is excellent and high temperature offset is suppressed as compared with Comparative Examples.
In addition, the examples α3 to α5, the reference examples α6 to α7, and the reference example γ1 are excellent in image storability as compared with the other examples.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to a first embodiment. FIG. 3 is a cross-sectional view illustrating an example of a printed matter manufactured by the image forming apparatus according to the first embodiment. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on a 2nd reference example . It is a schematic block diagram which shows an example of the image forming apparatus which concerns on a 3rd reference example . It is a schematic block diagram which shows an example of the image forming apparatus which concerns on a 4th reference example .

Explanation of symbols

1Y, 1M, 1C, 1K, 1S, 1B photoconductor (electrostatic latent image holder)
2Y, 2M, 2C, 2K, 2S, 2B Charger (charging means)
3Y, 3M, 3C, 3K, 3S, 3B Laser beam 3 Exposure device (electrostatic latent image forming means)
4Y, 4M, 4C, 4K, 4S, 4B Development device (developing means)
5Y, 5M, 5C, 5K, 5S, 5B Primary transfer roller 6Y, 6M, 6C, 6K, 6S, 6B Photoconductor cleaning device 8Y, 8M, 8C, 8K, 8S, 8B Toner cartridge 10Y, 10M, 10C, 10K 10S, 10B Unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer roller (transfer means)
28 Fixing device (fixing means)
30 Intermediate transfer member cleaning device P Recording paper (recording medium)

Claims (2)

A first electrostatic latent image holding member, first electrostatic latent image forming means for forming a first electrostatic latent image on a surface of the first electrostatic latent image holding member, and a first toner image directly contacting a recording medium. First developing means for developing the first electrostatic latent image with a developer containing non-colored toner as the first toner for forming, and the first toner formed by being developed by the first developing means First toner image forming means including first transfer means for transferring an image so as to be in direct contact with the surface of the recording medium;
A second electrostatic latent image holder, second electrostatic latent image forming means for forming a second electrostatic latent image on the surface of the second electrostatic latent image holder, and the recording medium via the first toner image. A second developing means for developing the second electrostatic latent image with a developer containing a colored toner as a second toner for forming a second toner image formed on the surface, and developed by the second developing means One or a plurality of second toner image forming means, including a second transfer means for transferring the second toner image formed thereby to the surface of the recording medium;
Fixing means for fixing the first toner image and the second toner image transferred on the surface of the recording medium to the recording medium;
The softening temperature of the first toner is lower than the softening temperature of the second toner,
The softening temperature of the second toner for forming the second toner image farthest from the recording medium among the second toner images is 90 ° C. or higher and 120 ° C. or lower ,
The softening temperature of the second toner for forming the farthest second toner image is the highest temperature among the softening temperatures of the second toner,
The image forming apparatus, wherein the first toner has a larger L * value in the CIE 1976 (L * a * b *) color system than all the second toners. A recording medium , a non-colored toner image that is a first toner image formed in direct contact with the surface of the recording medium, and one or a plurality of first images formed on the surface of the recording medium via the first toner image. A colored toner image that is a two-toner image,
The softening temperature of the first toner image is lower than the softening temperature of the second toner image ,
The softening temperature of the second toner image farthest from the recording medium among the second toner images is 90 ° C. or higher and 120 ° C. or lower,
The softening temperature of the second toner image farthest away is the highest temperature among the softening temperatures of the second toner image,
The first toner image is a printed matter having a larger L * value in the CIE 1976 (L * a * b *) color system than all the second toner images.

Images