JP7028006B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

In the formation of an image by the electrophotographic method, for example, after charging the surface of the image holder, an electrostatic charge image is formed on the surface of the image holder according to the image information, and then the static charge image is developed containing toner. It is performed by developing with an agent to form a toner image, and transferring and fixing the toner image on the surface of a recording medium.

Here, Patent Document 1 states that "an image holder that holds a toner image, a belt body that can move in contact with the image holder, and a position that faces the image holder across the belt body. A transfer member that is arranged in contact with the belt body and transfers the toner image on the image holder to the belt body or a transfer material held by the belt body, and a voltage for the transfer to the transfer member. In an image forming apparatus having a voltage applying means for applying a voltage, the transfer member has an elastic member and a sheet member sandwiched between the belt body and the elastic member and in contact with the belt body. An image forming apparatus in which the elastic member is electrically insulating is disclosed.

Further, Patent Document 2 states that "as a toner used for forming an image," in an electrophotographic toner containing a binder resin and a colorant, the binder resin contains 70 to 85 mol% of an aromatic dicarboxylic acid component. 0.1 to 1.2 mol of propoxylation and / or ethoxylation was carried out with respect to 1 mol of the carboxylic acid component composed of (a) and 15 to 30 mol% of a trivalent or higher valent carboxylic acid component (b). The acid value is 6 to 15 mgKOH / g and the weight average molecular weight Mw is 15,000 to 15,000, which is obtained by condensing the etherified diphenol component (c) and the aliphatic diol component (d) of 0.01 to 0.15 mol. 60,000, the number average molecular weight Mn is 2,000 to 4,000, the ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 6 to 18, the glass transition point is 50 to 60 ° C., and "Toner for electrophotographic photography, which is a polyester resin having a softening point of 100 to 120 ° C." is disclosed.

Japanese Unexamined Patent Publication No. 2008-310058 Japanese Unexamined Patent Publication No. 2000-056504

By the way, in an electrophotographic image forming apparatus, an electrostatic charge image formed on the surface of an image holder is developed with a developer containing toner to form a toner image, and the toner image is recorded from the image holder as a recording medium. After transferring to the surface of the image, the toner image is fixed to form an image on the recording medium. On the other hand, when an amorphous polyester resin is contained as the binder resin and the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the isocyanate-soluble component of the toner particles, Mw is 10,000 or more. It is 60,000 or less, Mw / Mn is 5 or more and 10 or less, and the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, and the wave number is 0.6 or less. A toner containing toner particles (hereinafter, also referred to as “specific toner”) having a ratio of the absorbance of wave number 820 cm ^-1 to the absorbance of 720 cm ^-1 is 0.4 or less tends to have high moisture absorption. Then, the chargeability of the toner is lowered due to the moisture absorbed (especially in a high temperature and high humidity environment (for example, 35 ° C., 85% environment)), and the transferability may be lowered. rice field.

Therefore, the first problem in the present invention is a transfer means for transferring a toner image formed on the surface of an image holder to the surface of a recording medium in an image forming apparatus to which a specific toner is applied. A belt member with which the outer peripheral surface is in contact, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and is convex in a state where the surface on the side that presses the belt member does not press the belt member. It is an object of the present invention to provide an image forming apparatus having high transferability of a toner image as compared with the case where a transfer means having only a pressing member is provided.
A second object of the present invention is a transfer means for transferring a toner image formed on the surface of an image holder to the surface of a recording medium by applying a specific toner, and the outer peripheral surface comes into contact with the image holder. In an image forming apparatus having a belt member and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, in the drive direction of the belt member in the contact region where the belt member contacts along the image holder. Compared with the case where the transfer means is provided in which the ratio [L _N / L _P × 100] of the length (L _N ) to the maximum length ( _LP ) of the pressing member in the driving direction of the belt member is less than 50%. The present invention provides an image forming apparatus having high transferability of a toner image.

The above problem is solved by the following invention. That is,

<1> Image holder and
A charging means for charging the surface of the image holder, and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The binder resin contains an amorphous polyester resin, and when the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles, Mw is 10,000 or more and 60,000 or less. Mw / Mn is 5 or more and 10 or less, and the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, ^and the wave number 720 cm-. An electrostatic charge image developer having a toner containing toner particles having a molecular weight 820 cm- ¹ absorbance ratio of ¹ to an absorbance of 0.4 or less is contained, and the electrostatic charge image developer is applied to the surface of the image holder. A developing means for developing the formed electrostatic charge image as a toner image, and
A belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and the surface on the side that presses the belt member is an elastic body. Yes, the surface on the side that presses the belt member is flat or concave in a state where the belt member is not pressed, has a pressing member that is not driven to rotate, and is a toner formed on the surface of the image holder. A transfer means for transferring an image to the surface of a recording medium,
An image forming apparatus.

<2> Image holder and
A charging means for charging the surface of the image holder, and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The binder resin contains an amorphous polyester resin, and when the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles, Mw is 10,000 or more and 60,000 or less. Mw / Mn is 5 or more and 10 or less, and the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, ^and the wave number 720 cm-. An electrostatic charge image developer having a toner containing toner particles having a molecular weight 820 cm- ¹ absorbance ratio of ¹ to an absorbance of 0.4 or less is contained, and the electrostatic charge image developer is applied to the surface of the image holder. A developing means for developing the formed electrostatic charge image as a toner image, and
A belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and the surface on the side that presses the belt member is an elastic body. The belt member of the pressing member, which has a pressing member that is not driven to rotate and has a length ( _LN ) in the driving direction of the belt member in a contact region where the belt member comes into contact with the image holder. The ratio [ _LN / _{LP ×} 100] to the maximum length (LP) in the driving direction is 50% or more and 98% or less, and the toner image formed on the surface of the image holder is the surface of the recording medium. And the transfer means to transfer to
An image forming apparatus.

<3> In the infrared absorption spectrum analysis of the toner particles, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.5 or less, and the absorbance of the wave number 820 cm ^-1 with respect to the absorbance of the wave number 720 cm ^-1 . The image forming apparatus according to <1> or <2>, wherein the ratio of the above is 0.3 or less.

<4> In the infrared absorption spectrum analysis of the toner particles, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.2 or more, and the absorbance of the wave number 820 cm ^-1 with respect to the absorbance of the wave number 720 cm ^-1 . The image forming apparatus according to any one of <1> to <3>, wherein the ratio of the above is 0.05 or more.

<5> The invention according to any one of <1> to <4>, wherein the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 1500 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.5 or less. Image forming device.

<6> The image forming apparatus according to <5>, wherein the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 1500 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.4 or less.

<7> The image according to any one of <1> to <6>, wherein the peak molecular weight of the molecular weight distribution curve obtained by gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles is 7000 or more and 11000 or less. Forming device.

<8> The image forming apparatus according to <7>, wherein the peak molecular weight of the molecular weight distribution curve obtained by gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles is 8000 or more and 11000 or less.

<9> The image forming apparatus according to any one of <1> to <8>, wherein the toluene insoluble content of the toner particles is 28% by mass or more and 38% by mass or less.

<10> The image forming apparatus according to <9>, wherein the toluene insoluble content of the toner particles is 30% by mass or more and 35% by mass or less.

<11> The image forming apparatus according to any one of <1> to <10>, wherein the toner particles contain a crystalline resin.

<12> The image forming apparatus according to <11>, wherein the content of the crystalline resin is 3% by mass or more and 20% by mass or less with respect to the total amount of the toner.

<13> The image forming apparatus according to <12>, wherein the content of the crystalline resin is 5% by mass or more and 15% by mass or less with respect to the total amount of the toner.

<14> The image forming apparatus according to any one of <1> to <13>, wherein the belt member is an intermediate transfer belt.

<15> The image forming apparatus according to any one of <1> to <14>, wherein the transfer means is a sheet member interposed between the belt member and the pressing member.

<16> The image forming apparatus according to any one of <1> to <15>, wherein the micro-hardness of the elastic body is 20 degrees or more and 60 degrees or less.

According to the invention according to <1>, in an image forming apparatus to which a specific toner is applied, it is a transfer means for transferring a toner image formed on the surface of an image holder to the surface of a recording medium, and is an outer periphery of the image holder. A belt member with which the surfaces come into contact, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and the surface on the side that presses the belt member is convex in a state where the belt member is not pressed. An image forming apparatus having high transferability of a toner image is provided as compared with the case where a transfer means having only a certain pressing member is provided.
According to the invention according to <2>, it is a transfer means for transferring a toner image formed on the surface of an image holder to the surface of a recording medium by applying a specific toner, and the outer peripheral surface comes into contact with the image holder. In an image forming apparatus having a belt member and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, the length in the drive direction of the belt member in the contact region where the belt member contacts along the image holder. Compared to the case where the transfer means is provided in which the ratio [L _N / _{L P ×} 100] of the pressing member to the maximum length ( _LP ) of the belt member in the driving direction is less than 50%. An image forming apparatus having high image transferability is provided.

According to the invention according to <3>, <4>, <5>, <6>, <7>, <8>, <14>, or <15>, an image is formed in an image forming apparatus to which a specific toner is applied. A transfer means for transferring a toner image formed on the surface of a holder to the surface of a recording medium, and a belt member whose outer peripheral surface contacts the image holder and a belt member from the inner peripheral surface side toward the image holder. When a transfer means having only a pressing member which is a pressing member to be pressed and whose surface on the side of pressing the belt member is convex in a state where the belt member is not pressed is provided, or formed on the surface of an image holder. A transfer means for transferring the printed toner image to the surface of a recording medium, the belt member having an outer peripheral surface in contact with the image holder, and a pressing member for pressing the belt member from the inner peripheral surface side toward the image holder. In the image forming apparatus, the maximum length ( _LP ) of the length in the drive direction of the belt member ( _LN ) in the contact region where the belt member contacts along the image holder, in the drive direction of the belt member of the pressing member. ), The image forming apparatus having high transferability of the toner image is provided as compared with the case where the transfer means is provided in which the ratio [L _N / L _P × 100] is less than 50%.
According to the invention according to <9> or <10>, an image forming apparatus having higher transferability of a toner image is provided as compared with the case where the toluene insoluble content of the toner particles is less than 28% by mass or more than 38% by mass. Toner.
According to the invention according to <11>, <12>, or <13>, an image forming apparatus having higher transferability of a toner image is provided as compared with the case where the toner particles do not contain a crystalline resin.
According to the invention according to <16>, there is provided an image forming apparatus having higher transferability of a toner image as compared with the case where the micro hardness of the elastic body in the pressing member exceeds 60 degrees.

It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of the state in which the pressing member is pressed against the image holding body through the belt member in the image forming apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of the state which the transfer member is arranged with respect to the image holder with respect to the image holder in the conventional image forming apparatus. It is a schematic diagram which shows an example of the pressing member used in this embodiment. It is a schematic diagram which shows another example of the pressing member used in this embodiment. It is a schematic diagram which shows an example of the pressing member different from the one used in this embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment. (A) is a schematic plan view showing an example of a circular electrode, and (B) is a schematic cross-sectional view thereof.

Hereinafter, embodiments that are an example of the present invention will be described in detail.

In the following, the image forming apparatus according to the "first embodiment" and the image forming apparatus according to the "second embodiment" will be described separately, but the explanation common to both will be simply referred to as "the present embodiment". The present invention will be described as relating to the image forming apparatus according to the above.

<Image forming device>
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, a static charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and a toner. A developing means for accommodating a static charge image developer and developing a static charge image formed on the surface of the image holder as a toner image by the static charge image developer, and a toner image formed on the surface of the image holder. Is provided with a transfer means for transferring the electric charge to the surface of the recording medium.
Further, the toner (specific toner) contains an amorphous polyester resin as a binder resin, and gel permeation chromatography (GPC) measurement of the tetrahydrofuran-soluble content (hereinafter, also referred to as “THF-soluble content”) of the toner particles is performed. When the weight average molecular weight is Mw and the number average molecular weight is Mn, Mw is 10,000 or more and 60,000 or less, Mw / Mn is 5 or more and 10 or less, ^and the wave number in the infrared absorption spectrum analysis of the toner particles is 720 cm-. It contains toner particles in which the ratio of the absorbance of wave number 1500 cm ^-1 to the absorbance of ¹ is 0.6 or less, and the ratio of the absorbance of wave number 820 cm ^-1 to the absorbance of wave number 720 cm ^-1 is 0.4 or less.

In the image forming apparatus according to the first embodiment, the transfer means is a belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder. The surface on the side that presses the belt member is an elastic body, and the surface on the side that presses the belt member is flat or concave in a state where the belt member is not pressed, and has a pressing member that is not driven to rotate.

Further, in the image forming apparatus according to the second embodiment, the transfer means is a belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder. The surface on the side that presses the belt member is an elastic body, and has a pressing member that is not driven to rotate. Then, the ratio of the length (L _N ) in the drive direction of the belt member in the contact region where the belt member contacts along the image holder to the maximum length ( _LP ) in the drive direction of the belt member of the pressing member. [L _N / L _P × 100] is 50% or more and 98% or less.

According to the image forming apparatus according to the first embodiment and the second embodiment having the above configuration, high transferability of the toner image in the transfer means is achieved.
The reason is inferred as follows.

Here, in the electrophotographic image forming apparatus, the electrostatic charge image formed on the surface of the image holder is developed with a developer containing toner to form a toner image, and the toner image is recorded from the image holder. After transferring to the surface of the medium, the toner image is fixed to form an image on the recording medium. As a method of transferring the toner image to the surface of the recording medium, a method of transferring the toner image directly from the image holder to the surface of the recording medium (direct transfer method) and a method of transferring the toner image from the image holder to the intermediate transfer body are primary. A method of transferring and further transferring a toner image on the intermediate transfer body to the surface of a recording medium (intermediate transfer method) is known. In the direct transfer method, a belt member (recording medium transfer belt) is used as a recording medium carrier for transporting the recording medium to the transfer position where the toner image formed on the surface of the image holder is transferred to the recording medium. In addition, a belt member (intermediate transfer belt) is used as an intermediate transfer body in the intermediate transfer method.

On the other hand, in the specific toner, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, and the wave number 820 cm ^-1 with respect to the absorbance of the wave number 720 cm ^-1 . The absorbance ratio of is 0.4 or less. The fact that the toner particles have this infrared absorption spectral characteristic means that the amorphous polyester resin as the binder resin has an alkylene oxide adduct of bisphenol A (ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A). , Ethylene oxide propylene oxide adduct of bisphenol A, etc.) is not used as a polyhydric alcohol, or even if it is used, it means that the resin is in a small amount.

Then, in order to improve the fixability of the fixed image using this specific toner, when the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles, Mw. Is 10,000 or more and 60,000 or less, and it is appropriate that Mw / Mn is 5 or more and 10 or less. That is, it is appropriate that the molecular weight characteristics of the non-crosslinked binder resin component mainly have the above characteristics.
Specifically, when Mw is less than 10,000, hot offset (a phenomenon in which toner is excessively melted and adheres to a fixing member) at the time of fixing is likely to occur even if a gel component is contained, and Mw is 60,000. If it exceeds, the minimum fixing temperature tends to increase. Further, when Mw / Mn exceeds 10, a difference occurs in the meltability of the resin, and unevenness is likely to occur in the fixed image. It is difficult in manufacturing to make Mw / Mn less than 5.
As described above, when the molecular weight characteristics of the specific toner (the toner particles thereof) are set to the above characteristics, the fixing property of the image is improved.

However, when a specific toner is used, the transferability may be deteriorated. The reason is presumed as follows. The specific toner is derived from the amorphous polyester resin and has a property of high hygroscopicity. Therefore, the chargeability of the specific toner decreases due to moisture absorption, and the decrease in chargeability becomes remarkable particularly in a high temperature and high humidity environment (for example, in an environment of 35 ° C. and 85%). Then, the transferability of the toner image from the image holder may be lowered due to the low charge of the specific toner.

Therefore, in the image forming apparatus according to the first embodiment, as a transfer means, a belt member whose outer peripheral surface comes into contact with the image holder and a pressing member which presses the belt member from the inner peripheral surface side toward the image holder. , The surface on the side that presses the belt member is an elastic body, and the surface on the side that presses the belt member is flat or concave in a state where the belt member is not pressed, and the transfer means having a pressing member that does not drive rotation. To apply.

As described above, by providing a pressing member which is an elastic body and whose pressing surface side is flat or concave on the inner peripheral surface side of the belt member, the image holding body is provided at the position pressed by the pressing member. A part of the belt member and a part of the belt member come into contact with each other. Then, a wide nip (contact area with a wide contact area) is formed. Further, the toner image that has been formed on the image holder and then moved to this nip region is pressed with a high pressure by the pressing force from the pressing member.
That is, in the transfer means of the direct transfer method, a wide nip is formed at the transfer position from the image holder to the recording medium, and the toner image is sandwiched between the image holder and the recording medium and the recording medium transport belt for a long time. At the same time, it is pressed with high pressure. Further, in the transfer means of the intermediate transfer method, a wide nip is formed at the primary transfer position from the image holder to the intermediate transfer belt, and the time for the toner image to be sandwiched between the image holder and the intermediate transfer belt becomes longer. , Pressed with high pressure.
As a result, the transferability of the toner image from the image holder to the surface of the recording medium (transferability from the image holder to the recording medium in the direct transfer method, and transferability from the image holder to the intermediate transfer body in the intermediate transfer method (intermediate transfer belt). ) Primary transferability to the surface) is improved, and high transferability can be obtained.

Further, in the image forming apparatus according to the second embodiment, as a transfer means, a belt member whose outer peripheral surface comes into contact with the image holder and a pressing member which presses the belt member from the inner peripheral surface side toward the image holder. , The surface on the side that presses the belt member is an elastic body, has a pressing member that is not driven to rotate, and is the length in the driving direction of the belt member in the contact region where the belt member contacts along the image holder ( _LN ). ), The transfer means in which the ratio [L _N / L _P × 100] to the maximum length ( _LP ) of the belt member in the driving direction of the pressing member is 50% or more and 98% or less is applied.

In this way, the length (L _N ) of the contact area between the belt member and the image holder is the maximum length (L) of the pressing member when pressed by the pressing member which is an elastic body from the inner peripheral surface side of the belt member. By controlling the ratio to _P ) as described above, a wide nip (contact area having a wide contact area) is formed. Further, the toner image that has been formed on the image holder and then moved to this nip region is pressed with a high pressure by the pressing force from the pressing member.
That is, in the transfer means of the direct transfer method, a wide nip is formed at the transfer position from the image holder to the recording medium, and the toner image is sandwiched between the image holder and the recording medium and the recording medium transport belt for a long time. At the same time, it is pressed with high pressure. Further, in the transfer means of the intermediate transfer method, a wide nip is formed at the primary transfer position from the image holder to the intermediate transfer belt, and the time for the toner image to be sandwiched between the image holder and the intermediate transfer belt becomes longer. , Pressed with high pressure.
As a result, the transferability of the toner image from the image holder to the surface of the recording medium (transferability from the image holder to the recording medium in the direct transfer method, and transferability from the image holder to the intermediate transfer body in the intermediate transfer method (intermediate transfer belt). ) Primary transferability to the surface) is improved, and high transferability can be obtained.

From the above, in the image forming apparatus according to the present embodiment (first embodiment or second embodiment), high transferability of the toner image can be obtained.

Next, the configuration of the image forming apparatus according to the present embodiment will be described in detail.

[Structure of image forming apparatus]
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, a static charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and a toner. A developing means for accommodating a static charge image developer and developing a static charge image formed on the surface of the image holder as a toner image by the static charge image developer, and a toner image formed on the surface of the image holder. Is provided with a transfer means for transferring the electric charge to the surface of the recording medium.

Then, in the first embodiment, the transfer means has the following configuration.
-Has a belt member in which the outer peripheral surface comes into contact with the image holder.
-Has a pressing member that presses the belt member from the inner peripheral surface side toward the image holder.
-The surface of the pressing member on the side that presses the belt member is an elastic body.
-The pressing member is flat or concave in a state where the surface on the side that presses the belt member does not press the belt member.
-The pressing member is not driven to rotate.

Further, in the second embodiment, the transfer means has the following configuration.
-Has a belt member in which the outer peripheral surface comes into contact with the image holder.
-Has a pressing member that presses the belt member from the inner peripheral surface side toward the image holder.
-The surface of the pressing member on the side that presses the belt member is an elastic body.
-The pressing member is not driven to rotate.
-Ratio of the length (L _N ) of the belt member in the drive direction in the contact region where the belt member contacts along the image holder to the maximum length ( _LP ) of the belt member in the drive direction of the pressing member [ L _N / L _P × 100] is the above-mentioned range.

In the first embodiment, the ratio [L _N / L _P × 100] is preferably in the above range.
Further, in the second embodiment, it is preferable to use a pressing member having a flat surface or a concave surface in a state where the surface on the side that presses the belt member does not press the belt member as the pressing member.

Here, an image forming apparatus that satisfies both the above-mentioned requirements in the first embodiment and the above-mentioned requirements in the second embodiment will be described with reference to the drawings.

In the transfer means of the present embodiment, the usage mode of the belt member is not particularly limited, and for example, an intermediate transfer belt in the transfer means of the intermediate transfer method, a recording medium transport belt in the transfer means of the direct transfer method, and the like are used. Can be mentioned.
If the belt member is provided as an intermediate transfer belt, the transfer means is a primary transfer means for primary transfer of the intermediate transfer belt (belt member) and the toner image formed on the surface of the image holder to the surface of the intermediate transfer belt. And a secondary transfer means for secondary transfer of the toner image transferred to the surface of the intermediate transfer belt to a recording medium. And the primary transfer means has at least a pressing member. This aspect will be described below as the first aspect.
Further, in the embodiment in which the belt member is provided as the recording medium transport belt, the transfer means is a recording medium transport belt that transports the recording medium to the transfer position where the toner image formed on the surface of the image holder is transferred to the recording medium. It has a configuration including (belt member) and a transfer means for transferring a toner image formed on the surface of an image holder to the surface of a recording medium. And the transfer means has at least a pressing member. This aspect will be described below as a second aspect.

-Structure of image forming apparatus (first aspect)-
First, an image forming apparatus using a belt member as an intermediate transfer belt in the transfer means will be described as an example.
FIG. 1 is a schematic configuration diagram showing a configuration of an image forming apparatus according to a first aspect.

As shown in FIG. 1, the image forming apparatus 100 according to the first aspect is, for example, an intermediate transfer type image forming apparatus generally called a tandem type, and a toner image of each color component is formed by an electrophotographic method. Each color component toner image formed by a plurality of image forming units 1Y, 1M, 1C, 1K and each image forming unit 1Y, 1M, 1C, 1K is sequentially transferred (primary transfer) to an intermediate transfer belt 15 (an example of a belt member). ), And the secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred on the intermediate transfer belt 15 to paper K (an example of a recording medium) which is a recording medium. A fixing device 60 for fixing the transferred image on the paper K is provided. Further, the image forming apparatus 100 has a control unit 40 that controls the operation of each device (each unit).

Each image forming unit 1Y, 1M, 1C, 1K of the image forming apparatus 100 includes a photoconductor 11 (an example of an image holder) that rotates in the direction of arrow A and holds a toner image formed on the surface.

A charger 12 for charging the photoconductor 11 is provided around the photoconductor 11 as an example of the charging means, and a laser exposure device 13 for writing a static charge image on the photoconductor 11 as an example of the latent image forming means. (The exposure beam in the figure is indicated by the reference numeral Bm) is provided.

Further, around the photoconductor 11, as an example of the developing means, a developer 14 in which each color component toner is accommodated and a static charge image on the photoconductor 11 is visualized by the toner is provided. A specific toner is used as at least one of the above-mentioned color component toners. In the first aspect, it is preferable that all of the color component toners are specific toners.

Further, a primary transfer device 16 is provided for transferring each color component toner image formed on the photoconductor 11 to the intermediate transfer belt 15 by the primary transfer unit 10.

As shown in FIG. 2, the primary transfer device 16 has an elastic pressing member 162 (an example of a pressing member) that presses toward the photoconductor 11 from the inner peripheral surface side of the intermediate transfer belt 15 and does not drive rotation. Further, a low friction sheet 164 (an example of the sheet member) is interposed between the intermediate transfer belt 15 and the elastic pressing member 162. When pressed by the elastic pressing member 162, a part of the photoconductor 11 and a part of the intermediate transfer belt 15 come into contact with each other so as to form a nip N between the photoconductor 11 and the intermediate transfer belt 15. Ru.
Details of the elastic pressing member 162 and the low friction sheet 164 will be described later.

Further, a photoconductor cleaner 17 for removing residual toner on the photoconductor 11 is provided around the photoconductor 11, and a charger 12, a laser exposure device 13, a developer 14, a primary transfer device 16, and a photoconductor cleaner are provided. 17 electrophotographic devices are sequentially arranged along the rotation direction of the photoconductor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. Has been done.

The intermediate transfer belt 15 is circulated (rotated) by various rolls in the B direction shown in FIG. 1 at a speed suitable for the purpose. These various rolls include a drive roll 31 driven by a motor (not shown) to rotate the intermediate transfer belt 15, and a support roll 32 that supports the intermediate transfer belt 15 extending substantially linearly along the arrangement direction of each photoconductor 11. , The tension applying roll 33 that applies tension to the intermediate transfer belt 15 and functions as a correction roll that suppresses the meandering of the intermediate transfer belt 15, the back roll 25 provided in the secondary transfer portion 20, and the residue on the intermediate transfer belt 15. It has a cleaning back roll 34 provided in a cleaning section for scraping toner.

The secondary transfer unit 20 includes a back surface roll 25 and a secondary transfer roll 22 arranged on the toner image holding surface side of the intermediate transfer belt 15.

The back roll 25 is made of, for example, a tube of a blended rubber of EPDM and NBR whose surface is dispersed with carbon, and the inside is made of EPDM rubber. Then, the surface resistivity is formed to be ¹⁰⁷ Ω / □ or more and 10 ¹⁰ Ω / □ or less, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Polymer Instruments Co., Ltd., the same applies hereinafter). To. The back surface roll 25 is arranged on the back surface side of the intermediate transfer belt 15 to form a counter electrode of the secondary transfer roll 22, and the metal feeding roll 26 to which the secondary transfer bias is stably applied is contact-arranged. ing.

On the other hand, the secondary transfer roll 22 is composed of a core body and a sponge layer as an elastic layer fixed around the core body. The core is a cylindrical rod made of metal such as iron and SUS. The sponge layer is formed of a blended rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black, and is a sponge-like cylindrical roll having a volume resistivity of 10 ^7.5 Ωcm or more and 10 ^8.5 Ω cm or less.

Then, the secondary transfer roll 22 is pressure-welded to the back roll 25 with the intermediate transfer belt 15 interposed therebetween, and the secondary transfer roll 22 is grounded to form a secondary transfer bias with the back roll 25. The toner image is secondarily transferred onto the paper K conveyed to the transfer unit 20.

Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, the intermediate transfer belt that cleans the surface of the intermediate transfer belt 15 by removing residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer. A cleaner 35 is provided so as to be detachable.

The intermediate transfer belt 15, the primary transfer unit 10 (primary transfer device 16), and the secondary transfer unit 20 (secondary transfer roll 22) correspond to an example of the transfer means.

On the other hand, on the upstream side of the yellow image forming unit 1Y, there is a reference sensor (home position sensor) 42 that generates a reference signal as a reference for taking the image forming timing in each image forming unit 1Y, 1M, 1C, 1K. It is arranged. Further, an image density sensor 43 for adjusting the image quality is arranged on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. According to an instruction from the control unit 40 based on the recognition of the reference signal, each image forming unit 1Y, 1M, 1C, 1K are configured to initiate image formation.

Further, in the image forming apparatus according to the first aspect, as the transporting means for transporting the paper K, the paper accommodating unit 50 accommodating the paper K and the paper K accumulated in the paper accommodating unit 50 are stored at predetermined timings. A paper feed roll 51 that is taken out and conveyed, a transfer roll 52 that conveys the paper K fed by the paper feed roll 51, a transfer guide 53 that feeds the paper K conveyed by the transfer roll 52 to the secondary transfer unit 20, and a secondary. It is provided with a transport belt 55 for transporting the paper K to be transported after being secondarily transferred by the transfer roll 22 to the fixing device 60, and a fixing inlet guide 56 for guiding the paper K to the fixing device 60.

Next, the basic image forming process of the image forming apparatus according to the first aspect will be described.
In the image forming apparatus according to the first aspect, the image data output from an image reading device (not shown), a personal computer (PC) (not shown), or the like is subjected to image processing by an image processing device (not shown) and then an image forming unit. The image drawing work is executed by 1Y, 1M, 1C, and 1K.

The image processing device performs image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame erasing and color editing, and various image editing such as movement editing on the input reflectance data. Will be done. The image data that has undergone image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the laser exposure device 13.

In the laser exposure device 13, for example, the exposure beam Bm emitted from the semiconductor laser is applied to the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. .. In each of the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charging device 12, and then the surface is scanned and exposed by the laser exposure device 13 to form a static charge image. The formed static charge image is developed as a toner image of each color of Y, M, C, and K by each image forming unit 1Y, 1M, 1C, and 1K.

The toner image formed on the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K is intermediate at the nip N formed in the primary transfer unit 10 in which each photoconductor 11 and the intermediate transfer belt 15 are in contact with each other. It is transferred onto the transfer belt 15. More specifically, in the primary transfer unit 10, the primary transfer device 16 applies a voltage having a charge polarity (negative polarity) and a reverse polarity (primary transfer bias) of the toner to the base material of the intermediate transfer belt 15, and the toner image. Is sequentially superposed on the surface of the intermediate transfer belt 15, and the primary transfer is performed.

After the toner image is sequentially primary-transferred to the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is transferred to the secondary transfer unit 20. When the toner image is conveyed to the secondary transfer unit 20, the transfer means rotates the paper feed roll 51 in accordance with the timing at which the toner image is transferred to the secondary transfer unit 20, and the target is from the paper storage unit 50. Paper K of size is supplied. The paper K supplied by the paper feed roll 51 is conveyed by the transfer roll 52 and reaches the secondary transfer unit 20 via the transfer guide 53. Before reaching the secondary transfer unit 20, the paper K is temporarily stopped, and the alignment roll (not shown) rotates according to the movement timing of the intermediate transfer belt 15 on which the toner image is held, so that the paper K is formed. The position of is aligned with the position of the toner image.

In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the back roll 25 via the intermediate transfer belt 15. At this time, the paper K conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At that time, when a voltage (secondary transfer bias) having the same polarity as the charging polarity (minus polarity) of the toner is applied from the feeding roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the back surface roll 25. Will be done. Then, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred onto the paper K collectively in the secondary transfer unit 20 pressurized by the secondary transfer roll 22 and the back surface roll 25. Toner.

After that, the paper K on which the toner image is electrostatically transferred is conveyed as it is in a state of being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is provided on the downstream side of the secondary transfer roll 22 in the paper transfer direction. It is transported to the belt 55. The transport belt 55 transports the paper K to the fixing device 60 according to the optimum transport speed in the fixing device 60. The unfixed toner image on the paper K conveyed to the fixing device 60 is fixed on the paper K by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the paper K on which the fixed image is formed is conveyed to a paper ejection accommodating portion (not shown) provided in the ejection unit of the image forming apparatus.

On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and is conveyed to the cleaning section by the cleaning back roll 34 and the intermediate transfer belt cleaner 35. It is removed from the intermediate transfer belt 15.

Configuration of the primary transfer unit As shown in FIG. 2, the primary transfer unit 10 presses the intermediate transfer belt 15 from the inner peripheral surface side toward the photoconductor 11 and does not rotate to drive the elastic pressing member 162 (of the pressing member). It is composed of a primary transfer device 16 having a low friction sheet 164 (an example of a sheet member) interposed between an intermediate transfer belt 15 and an elastic pressing member 162 (an example).

In the primary transfer unit 10, the intermediate transfer belt 15 is pressed by the elastic pressing member 162, so that a part of the photoconductor 11 and a part of the intermediate transfer belt 15 come into contact with each other. Therefore, as shown in FIG. 3, the intermediate transfer belt 15 is arranged so as to be sandwiched together with the photoconductor 11, and the intermediate transfer between the photoconductor 11 and the intermediate transfer is performed as compared with the primary transfer device provided with the transfer roll 66 which is rotationally driven in the direction of arrow C. A wide nip N is formed between the belt 15 and the belt 15.

(Pressing member)
The elastic pressing member 162, which is an example of the pressing member, is not rotationally driven. As shown in FIG. 2, "not driven by rotation" means that the same surface is continuously pressed against the photoconductor 11 rotating in the direction of arrow A and the intermediate transfer belt 15 driven in the direction of arrow B to perform intermediate transfer. It means that the belt 15 is arranged so as to keep pressing the photoconductor 11 side.

The shape of the elastic pressing member 162 is a flat surface or a concave surface in a state where the surface on the side that presses the belt member does not press the belt member.
That is, as shown in FIG. 4, the elastic pressing member 162 has a concave elasticity in a free state in which the surface a on the side that presses the belt member does not press the belt member or the like (no external pressure is applied). It may be the pressing member 162A. Further, as shown in FIG. 5, the elastic pressing member 162 has a planar elasticity in a free state in which the surface a on the side that presses the belt member does not press the belt member or the like (no external pressure is applied). It may be the pressing member 162B.
However, the pressing member in the present embodiment has a convex surface in a free state in which the surface a on the side that presses the belt member does not press the belt member or the like (no external pressure is applied) as shown in FIG. The pressing member 162C having a shape is not included.

In the elastic pressing member 162, at least the surface on the side that presses the belt member is an elastic body. The elastic pressing member 162 is entirely made of an elastic body.
The "elastic body" refers to a material made of a material that restores its original shape even when it is deformed by an external force in an environment such as temperature and humidity where the image forming apparatus is expected to be used.

The elastic body preferably has a micro hardness of 20 degrees or more and 60 degrees or less. Further, the micro hardness is more preferably 25 degrees or more and 55 degrees or less, and further preferably 30 degrees or more and 50 degrees or less.
When the micro-hardness of the elastic body is 60 degrees or less, a wide nip N is well formed between the photoconductor 11 and the intermediate transfer belt 15, and high transferability of the toner image can be easily obtained. On the other hand, when the micro hardness of the elastic body is 20 degrees or more, a uniform nip is formed, and the effect that high transferability of the toner image can be easily obtained can be obtained.

The micro-hardness of an elastic body refers to the hardness measured by an MD-1 type hardness tester manufactured by Polymer Meter Co., Ltd.
Specifically, a sample to be measured is cut out to prepare a sample, and the hardness of the sample from the side pressed against the image holder is measured using a hardness tester (MD-1 manufactured by Polymer Meter Co., Ltd.). .. In principle, it conforms to the Type A durometer described in JIS K6253-3 (2012), and the push needle is pressed against the surface of the sample by the force of the spring to give deformation, and the resistance of the sample and the force of the spring are combined. It is measured based on the pushing depth of the push needle in a balanced state.
The diameter of the push needle is 0.16 mm, the amount of protrusion from the pressurized surface at the time of non-measurement (displacement of the push needle is 0 mm) is 0.5 mm, and the push needle is pushed by a spring with a force of 22 mN. ing. The micro hardness at this time is 0 °. When the pushing depth of the pushing needle is 0 mm (displacement 0.5 mm), the pushing needle is pushed by the spring with a force of 330 mN. The micro hardness at this time is 100 °. Then, the scales are set at equal intervals between them, and a micro-hardness measurement scale is used. The pressure surface of the hardness tester has an outer diameter of 4 mm and is provided with a hole having a diameter of 1.5 mm in the center through which the push needle is passed.
With the measuring machine having the above configuration, the push needle is pressed against the sample, and the value in a well-balanced state is read and used as the microhardness. The relationship between the micro hardness Hm (degrees) and the needle tip load F (mN) is as shown in the following formula.
Formula: F = 22 + 3.1Hm

Examples of the material of the elastic body include urethane foam rubber, ethylene propylene / propylene diene rubber (EPDM), acrylonitrile butadiene rubber, epichlorohydrin rubber and the like.
Among these, urethane foam rubber or ethylene propylene / propylene / diene rubber (EPDM) foamed is more preferable.

The elastic pressing member 162 may be a conductive member or an insulating member. When imparting conductivity, it is preferable that the volume resistivity is in the range of ¹⁰⁴ Ω · cm or more and ¹⁰⁸ Ω · cm or less by, for example, a method of adding a conductive agent such as carbon black. On the other hand, in the case of an insulating member, the volume resistivity is preferably in the range of more than 10 ¹⁰ Ω · cm.
However, when the low friction sheet 164 is interposed between the intermediate transfer belt 15 and the elastic pressing member 162, it is preferable to use the low friction sheet 164 as a conductive member to perform a voltage application function. From the viewpoint, the elastic pressing member 162 is preferably an insulating member.

In the image forming apparatus of the first aspect, the elastic pressing member 162 is pressed toward the photoconductor 11 from the inner peripheral surface side of the intermediate transfer belt 15. In the image forming apparatus of the first aspect, the length of the intermediate transfer belt 15 in the driving direction (arrow B direction) in the contact region (that is, nip N) where the intermediate transfer belt 15 contacts along the photoconductor 11 is determined. As shown in FIG. 2, (L _N ) is used, and when the maximum length of the intermediate transfer belt 15 of the elastic pressing member 162 in the driving direction (arrow B direction) is set to ( _LP ) as shown in FIG. 2, the ratio [ L _N / L _P × 100] is 50% or more and 98% or less.
The ratio [L _N / L _P × 100] is more preferably 65% or more and 98% or less, and further preferably 80% or more and 98% or less.
When the ratio [L _N / L _P × 100] is 50% or more, a wide nip N is formed between the photoconductor 11 and the intermediate transfer belt 15, and high transferability of the toner image can be obtained.

(Seat member)
A low friction sheet 164 as an example of the sheet member is interposed between the intermediate transfer belt 15 and the elastic pressing member 162.

The low friction sheet 164 preferably has a lower coefficient of friction than the elastic pressing member 162. By interposing a low friction sheet 164 having a friction coefficient lower than that of the elastic pressing member 162, an increase in torque due to friction between the intermediate transfer belt 15 and the primary transfer device 16 is suppressed.

The low friction sheet 164 is preferably made of a conductive member. That is, it is preferable to connect the low friction sheet 164 to a power source (not shown) so that the low friction sheet 164 has a function of applying a voltage to the primary transfer position 10. As a result, a voltage (primary transfer bias) having a polarity opposite to that of the toner charging polarity (minus polarity; the same applies hereinafter) is applied to the primary transfer device 16. Then, the toner images on each photoconductor 11 are sequentially electrostatically sucked onto the intermediate transfer belt 15, and the superimposed toner image is formed on the intermediate transfer belt 15.
When the low friction sheet 164 is made conductive, its volume resistivity is preferably in the range of ¹⁰⁴ Ωcm or more and ¹⁰⁸ Ωcm or less.

Examples of the material of the low friction sheet 164 include a material in which a conductive agent is contained in a resin.
Examples of the resin used for the low friction sheet 164 include polyimide resin, fluoride polyimide resin, polyamide resin, polyamideimide resin, polyether ether ester resin, polyarylate resin, polyester resin and the like, and among these, polyimide resin is used. preferable. For the low friction sheet 164, one type of resin may be used alone, or two or more types may be used in combination.
Examples of the conductive agent added to the low-friction sheet 164 include carbon black (for example, Ketjen black, acetylene black, carbon black whose surface has been oxidized), carbon fibers, carbon nanotubes, carbon-based substances such as graphite, and metals. Or alloys (eg aluminum, nickel, copper, silver, etc.), metal oxides (eg, yttrium oxide, tin oxide, indium oxide, antimony oxide, SnO ₂ -In ₂ O ₃ composite oxides, etc.), ionic conductive materials (eg, etc.) Examples thereof include potassium titanate, LiCl, etc.), and among these, carbon black is preferable.

The thickness of the low-friction sheet 164 is preferably, for example, 100 μm or more and 300 μm or less, preferably 150 μm or more, from the viewpoint of material life and susceptibility to change in shape according to the shape of the photoconductor for forming a good nip. It is more preferably 250 μm or less.

Although the image forming apparatus according to the first aspect has been described above, the present embodiment is not limited to this first aspect, and various modifications, changes, and improvements can be made.

-Structure of image forming apparatus (second aspect)-
Next, an image forming apparatus using a belt member as a recording medium transport belt (paper transport belt) in the transfer means will be described as an example.
FIG. 7 is a schematic configuration diagram showing the configuration of the image forming apparatus according to the second aspect.

In the image forming apparatus 200 shown in FIG. 7, the units Y, M, C, and BK are provided with photoconductors 201Y, 201M, 201C, and 201BK (an example of an image holder) so as to rotate in the clockwise direction of the arrow A, respectively. Be done. Around the photoconductors 201Y, 201M, 201C, and 201BK, there are chargers 202Y, 202M, 202C, 202BK (an example of charging means) and exposure devices 214Y, 214M, 214C, 214BK (an example of an electrostatic charge image forming means). , Each color developing device (yellow developing device 203Y, magenta developing device 203M, cyan developing device 203C, black developing device 203BK) (an example of developing means) and photoconductor cleaning members 204Y, 204M, 204C, 204BK are arranged respectively. There is.
The specific toner is housed in at least one of the above-mentioned color developing devices. In the second aspect, it is preferable that all of the color developing devices contain the specific toner.

Four units Y, M, C, and BK are arranged in parallel with respect to the paper transport belt 207 (an example of a belt member) in the order of units BK, C, M, and Y, but units BK, Y, and C are arranged in this order. , M, etc., an appropriate order is set according to the image forming method.

The paper transport belt 207 is supported from the inner surface side by four belt support rolls 206 to form a paper transport belt unit. The paper transport belt 207 rotates in the counterclockwise direction of the arrow B at the same peripheral speed as the photoconductors 201Y, 201M, 201C, and 201BK, and a part of the paper transport belt 207 located between the belt support rolls 206 is the photoconductor 201Y. , 201M, 201C, 201BK, respectively.

Transfer devices 216Y and 216M are located at the transfer positions where the color component toner images formed on the photoconductors 201Y, 201M, 201C, and 201BK are transferred onto the paper 215 (an example of a recording medium) conveyed by the paper transfer belt 207. , 216C, 216BK (an example of transfer means) are provided.

The transfer device 216 is the photoconductor 201Y, 201M, 201C, or 201BK from the inner peripheral surface side of the paper transport belt 207, similarly to the primary transfer device 16 (see FIG. 2) in the image forming device according to the first aspect. It has an elastic pressing member (an example of a pressing member) that presses in a direction and does not drive rotation. Further, a low friction sheet (an example of a sheet member) is interposed between the paper transport belt 207 and the elastic pressing member. When pressed by the elastic pressing member, a part of the photoconductor 201Y, 201M, 201C, or 201BK and a part of the paper transport belt 207 come into contact with each other so as to be in contact with the photoconductor 201Y, 201M, 201C, or 201BK. A nip N is formed between the paper transport belt 207 and the paper transport belt 207.

The preferred embodiment of the "elastic pressing member" and the "low friction sheet" in the transfer device 216Y, 216M, 216C, and 216BK of the second aspect is the same as the elastic pressing member 162 and the low friction sheet 164 in the first aspect described above. Therefore, the description thereof is omitted here.

The transfer device 216Y, 216M, 216C, and 216BK form a transfer region for transferring the toner image to the paper 215 via the photoconductors 201Y, 201M, 201C, and 201BK and the paper transport belt 207.

The cleaning blade 212 is arranged on the paper transport belt 207 so as to come into contact with the surface (outer peripheral surface) on the paper transport side. Further, a cleaning facing roll 213 as a conductive facing member is contacted and arranged on the opposite surface of the cleaning blade 212 via the paper transport belt 207 to form a paper transport belt cleaning device 220. There is.

In addition to the cleaning blade 212, the paper transport belt cleaning device 220 may be further provided with brush cleaning, roll cleaning, scraper cleaning, and the like.

The fixing device 210 (an example of the fixing means) is arranged so as to be conveyed after passing through the respective transfer regions of the paper transport belt 207 and the photoconductors 201Y, 201M, 201C, and 201BK.

The paper 215 is transported to the paper transport belt 207 by the paper transport roll 208.

In the image forming apparatus shown in FIG. 7, in the unit BK, the photoconductor 201BK is rotationally driven. In conjunction with this, the charger 202BK is driven to charge the surface of the photoconductor 201BK to the desired polarity and potential. The photoconductor 201BK whose surface is charged is then exposed to an image by the exposure device 214BK, and a static charge image is formed on the surface thereof.

Subsequently, the static charge image is developed by the black developer 203BK. Then, a toner image is formed on the surface of the photoconductor 201BK. The developer at this time may be a one-component type or a two-component type.

This toner image passes through the nip N formed in the transfer region between the photoconductor 201BK and the paper transport belt 207, and the paper 215 is electrostatically attracted to the paper transport belt 207 and transported to the transfer region, and is transported to the transfer device. It is sequentially transferred to the surface of the paper 215 by the electric field formed by the transfer bias applied from the 216BK.

After that, the toner remaining on the photoconductor 201BK is cleaned and removed by the photoconductor cleaning member 204BK. Then, the photoconductor 201BK is used for the next image transfer.

The above image transfer is also performed in units C, M and Y by the above method.

The paper 215 on which the toner image is transferred by the transfer device 216BK, 216C, 216M and 216Y is further transferred to the fixing device 210 for fixing.

Residual toner is removed from the photoconductors 201Y, 201M, 201C, and 201BK after transfer by the photoconductor cleaning members 204Y, 204M, 204C, and 204BK. On the other hand, in the paper transport belt 207 after transporting the recording medium 215, residual toner is removed by the cleaning blade 212 in the paper transport belt cleaning device 220 to prepare for the next image forming process.
As a result, an image is formed on the paper.

Although the image forming apparatus according to the second aspect has been described above, the present embodiment is not limited to this second aspect, and various modifications, changes, and improvements can be made.

As the aspect of the image forming apparatus according to the first and second aspects, for example, a normal monocolor image forming apparatus which accommodates only a monochromatic toner in a developing apparatus may be used.

-Belt member in the transfer means Next, the belt member used in the transfer means (intermediate transfer belt 15 in the first aspect, paper transport belt 207 in the second aspect) will be described.

The belt member may be composed of, for example, a resin material. Further, a conductive agent may be contained from the viewpoint of imparting conductivity, and other well-known additives may be contained.

Examples of the resin material used for the belt member include polyimide resin, fluoropolyimide resin, polyamide resin, polyamideimide resin, polyether ether ester resin, polyarylate resin, polyester resin and the like. For each belt member, one type of resin material may be used alone, or two or more types may be used in combination.

Among these, at least one of the polyimide resin and the polyamide-imide resin can be used from the viewpoint of increasing the rigidity of the inner peripheral surface and obtaining the difficulty of deformation when the rolls are stretched under tension. More preferred.

The belt member may contain a conductive agent from the viewpoint of imparting conductivity.
Examples of the conductive agent include conductivity (for example, volume resistivity less than ^{107 Ω · cm, the same applies hereinafter) or semi-conductive (for example, volume resistivity 10 7 Ω} · cm or more and 10 ¹³ Ω · cm or less, the same applies hereinafter). ) Particles.
As the conductive agent, particles having a primary particle size of less than 10 μm are preferable, and particles having a primary particle size of 1 μm or less are more preferable.

The conductive agent is not particularly limited, but is, for example, carbon black (for example, Ketjen black, acetylene black, carbon black whose surface has been oxidized), carbon fiber, carbon nanotube, carbon-based substance such as graphite, metal, or the like. Alloys (eg aluminum, nickel, copper, silver, etc.), metal oxides (eg, yttrium oxide, tin oxide, indium oxide, antimony oxide, SnO ₂ - _{In 2} O3 composite oxides, etc.), ionic conductive materials (eg titanium). Potassium acid, LiCl, etc.) and the like.

The conductive agent is selected according to the purpose of use, but carbon black is preferable, and the pH is 5 or less (preferably pH 4) from the viewpoint of the stability of the electric resistance over time and the electric field dependence that suppresses the electric field concentration due to the transfer voltage. An oxidation-treated carbon black having a pH of 5.5 or less, more preferably pH 4.0 or less (for example, carbon black obtained by imparting a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface) is preferable.

The content of the conductive agent in the belt member is selected according to the desired resistance. For example, it is preferably 1% by mass or more and 50% by mass or less, and further 2% by mass or more and 40% by mass with respect to the total mass of the belt member. The following is more preferable, and 4% by mass or more and 30% by mass or less is further preferable.
The conductive agent may be used alone or in combination of two or more.

Other additives other than the conductive agent include, for example, a dispersant for improving the dispersibility of the conductive agent (carbon black, etc.), various fillers for imparting various functions such as mechanical strength, a catalyst, and a film forming film. Leveling agent for improving quality, releasable material for improving releasability (for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexa) Fluororesin particles such as fluoropropylene copolymer (FEP)) and the like.

From the viewpoint of transferability, the surface resistivity of the outer peripheral surface of the belt member used for the transfer means is preferably 9 (LogΩ / □) or more and 13 (LogΩ / □) or less as a common logarithmic value, and is preferably 10 (LogΩ / □). It is more preferable that it is □) or more and 12 (LogΩ / □) or less.
The common logarithmic value of the surface resistivity is controlled by the type of the conductive agent and the amount of the conductive agent added.

Here, the method for measuring the surface resistivity is as follows. Measurement is performed according to JIS-K6911 (1995) using a circular electrode (for example, "UR probe" of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method of measuring the surface resistivity will be described with reference to the drawings. FIG. 8A is a schematic plan view showing an example of a circular electrode, and FIG. 8B is a schematic cross-sectional view thereof. The circular electrode shown in FIG. 8 includes a first voltage application electrode A and a plate-shaped insulator B. The first voltage application electrode A has a columnar electrode portion C and an inner diameter larger than the outer diameter of the columnar electrode portion C, and is a cylindrical ring-shaped electrode that surrounds the columnar electrode portion C at regular intervals. A part D is provided. A belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the plate-shaped insulator B, and the columnar electrode portion C and the ring-shaped electrode of the first voltage application electrode A are sandwiched between them. The current I (A) flowing when the voltage V (V) is applied to the portion D is measured, and the surface resistance ρs (Ω / □) of the transfer surface of the belt T is calculated by the following formula. Here, in the following formula, d (mm) indicates the outer diameter of the columnar electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
Equation: ρs = π × (D + d) / (D−d) × (V / I)
For the surface resistivity, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

The total volume resistivity of the belt member is, for example, 8 (LogΩcm) or more and 13 (LogΩcm) as a common logarithmic value from the viewpoint of transferability when used as an intermediate transfer belt, a recording medium transport belt, or the like in an image forming apparatus. ) The following is preferable. The common logarithmic value of the volume resistivity is controlled by the type of the conductive agent and the amount of the conductive agent added.

Here, the volume resistivity is measured according to JIS-K6911 (1995) using a circular electrode (for example, a UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method for measuring the volume resistivity will be described with reference to FIG. The measurement is performed with the same device as the surface resistivity. However, in the circular electrode shown in FIG. 8, a second voltage application electrode B'is provided instead of the plate-shaped insulator B at the time of measuring the surface resistivity. Then, a belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the second voltage application electrode B', and the columnar electrode portion C of the first voltage application electrode A is sandwiched between them. The current I (A) flowing when the voltage V (V) is applied between the and the second voltage application electrode B is measured, and the volume resistance ρv (Ωcm) of the belt T is calculated by the following formula. Here, in the following formula, t indicates the thickness of the belt T.
Equation ρv = 19.6 × (V / I) × t
For the volume resistivity, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

Further, the numerical value of 19.6 shown in the above equation is an electrode coefficient for converting into resistivity, and is πd ² from the outer diameter d (mm) of the columnar electrode portion and the thickness t (cm) of the sample. Calculated as / 4t. The thickness of the belt T is measured using an eddy current type film thickness meter CTR-1500E manufactured by Sanko Electronics Co., Ltd.

The thickness (average thickness) of the belt member is preferably 0.05 mm or more and 0.5 mm or less, more preferably 0.06 mm or more and 0.30 mm or less, and further preferably 0.06 mm or more and 0.15 mm or less.

[Static charge image developer]
Next, in the image forming apparatus according to the present embodiment, the static charge image developer (hereinafter, also referred to as “static charge image developer according to the present embodiment”) accommodated in the developing means will be described in detail.

The electrostatic charge image developer according to this embodiment contains at least toner.
The electrostatic charge image developer according to the present embodiment may be a one-component developer containing only toner or a two-component developer containing only toner and a carrier.

<Toner>
The toner has toner particles. The toner may have an external additive together with the toner particles.

(Toner particles)
The toner particles include, for example, a binder resin. The toner particles may contain a colorant, a mold release agent, other additives and the like.

-Bound resin-
As the binder resin, an amorphous polyester resin is applied.
Here, the amorphous resin is not a clear endothermic peak but has only a stepped endothermic change in the thermal analysis measurement using differential scanning calorimetry (DSC), and is a room temperature solid and has a glass transition. Refers to those that are thermoplastic at temperatures above the temperature.
On the other hand, the crystalline resin refers to a resin having a clear endothermic peak instead of a stepwise change in endothermic amount in differential scanning calorimetry (DSC).
Specifically, for example, the crystalline resin means that the half-value width of the endothermic peak when measured at a temperature rise rate of 10 ° C./min is within 10 ° C., and the amorphous resin means the half-value width. Means a resin having a temperature exceeding 10 ° C. or a resin in which a clear endothermic peak is not observed.

Examples of the amorphous polyester resin include a condensed polymer of a polyvalent carboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product may be used, or a synthetic resin may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.). , Alicyclic dicarboxylic acid (eg cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acid (eg, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), these anhydrides, or their lower grades (eg, 1 or more carbon atoms). 5 or less) Alkyl ester can be mentioned. Among these, as the polyvalent carboxylic acid, for example, an aromatic dicarboxylic acid is preferable.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
The polyvalent carboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include aliphatic diols (eg, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butane diol, hexane diol, neopentyl glycol, etc.), alicyclic diols (eg, cyclohexanediol, cyclohexanedimethanol, etc.). Hydrogenated bisphenol A and the like), aromatic diols (for example, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A and the like) can be mentioned. Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used in combination with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
The polyhydric alcohol may be used alone or in combination of two or more.

However, bisphenol A alkylene oxide adducts (bisphenol A ethylene oxide adducts, bisphenol A propylene oxide adducts, bisphenol A ethylene oxide propylene oxide adducts, etc.) are not used or used as polyhydric alcohols. Also in a small amount. Specifically, when an alkylene oxide adduct of bisphenol A is used, the amount used may be more than 0 mol% and 5 mol% or less with respect to the total polyhydric alcohol.

The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically described in JIS K 7121-1987 "Method for measuring the transition temperature of plastics". It is obtained by the "extra glass transition start temperature" of.

The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, more preferably 7,000 or more and 500,000 or less, and further preferably 30,000 or more and 50,000 or less.
The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2000 or more and 100,000 or less.
The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed by using Tosoh's GPC / HLC-8120GPC as a measuring device, using Tosoh's column / TSKgel SuperHM-M (15 cm), and using a THF solvent. The weight average molecular weight and the number average molecular weight are calculated from this measurement result using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

The amorphous polyester resin is obtained by a well-known manufacturing method. Specifically, for example, it can be obtained by a method in which the polymerization temperature is 180 ° C. or higher and 230 ° C. or lower, the pressure inside the reaction system is reduced as necessary, and the reaction is carried out while removing water and alcohol generated during condensation.
When the raw material monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a dissolution aid to dissolve the monomer. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If there is a monomer with poor compatibility, it is advisable to condense the monomer with poor compatibility in advance with the monomer and the acid or alcohol to be polycondensed, and then polycondensate with the main component. ..

The content of the amorphous polyester resin is preferably 60% by mass or more and 98% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and 80% by mass or more and 98% by mass or less in proportion to the total binder resin. Is more preferable.

Here, it is preferable to use a crystalline resin together with the amorphous polyester resin. When the crystalline resin is used in combination, the hygroscopicity of the toner particles is reduced, and the transferability of the toner image is easily improved. However, the crystalline polyester resin may be used in a range of 2% by mass or more and 40% by mass or less (preferably 2% by mass or more and 20% by mass or less) with respect to the total binder resin.

Examples of the crystalline resin include known crystalline resins such as crystalline polyester resin and crystalline vinyl resin (for example, polyalkylene resin, long-chain alkyl (meth) acrylate resin, etc.). Among these, a crystalline polyester resin is preferable from the viewpoint of enhancing the transferability of the toner image.

Examples of the crystalline polyester resin include a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.
Here, since the crystalline polyester resin easily forms a crystal structure, a polycondensate using a polymerizable monomer having a linear aliphatic is preferable to a polymerizable monomer having an aromatic.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonandicarboxylic acid, 1,10-decandicarboxylic acid). Acids, 1,12-dodecanedicarboxylic acids, 1,14-tetradecanedicarboxylic acids, 1,18-octadecanedicarboxylic acids, etc.), aromatic dicarboxylic acids (eg, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid) Examples thereof include dibasic acids such as acids), these anhydrides, or lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (for example, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.). Examples thereof include anhydrides or lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.
The polyvalent carboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include an aliphatic diol (for example, a linear aliphatic diol having 7 or more and 20 or less carbon atoms in the main chain portion). Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-. Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Examples thereof include octadecanediol and 1,14-eicosanedecanediol. Among these, as the aliphatic diol, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol are preferable.
As the polyhydric alcohol, a trihydric or higher alcohol having a crosslinked structure or a branched structure may be used in combination with the diol. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like.
The polyhydric alcohol may be used alone or in combination of two or more.

Here, the polyhydric alcohol often has an aliphatic diol content of 80 mol% or more, preferably 90 mol% or more.

The melting temperature of the crystalline polyester resin is preferably 50 ° C. or higher and 100 ° C. or lower, more preferably 55 ° C. or higher and 90 ° C. or lower, and further preferably 60 ° C. or higher and 85 ° C. or lower.
The melting temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC) by the "melting peak temperature" described in the method for obtaining the melting temperature in JIS K7121-1987 "Method for measuring the transition temperature of plastics".

The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

The crystalline polyester resin can be obtained by a well-known manufacturing method, as in the case of amorphous polyester, for example.

The content of the crystalline resin (preferably crystalline polyester resin) is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the total amount of the toner. When the content of the crystalline resin is within the above range, it becomes easy to improve the transferability of the toner image.

As the binder resin, an amorphous polyester resin and a binder resin other than the crystalline resin may be used in combination. However, the content of the other binder resin is preferably 10% by mass or less in proportion to the total binder resin.

Examples of other binder resins include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, etc.). N-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (eg, 2-ethylhexyl methacrylate) Acrylonitrile, methacrylonitrile, etc.), vinyl ethers (eg, vinylmethyl ether, vinylisobutyl ether, etc.), vinyl ketones (vinylmethylketone, vinylethylketone, vinylisopropenylketone, etc.), olefins (eg, ethylene, propylene, butadiene, etc.) ) Or a homopolymer of a monomer such as), or a vinyl-based resin composed of a copolymer obtained by combining two or more kinds of these monomers.
Examples of other binder resins include non-vinyl resins such as epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures of these with the vinyl resins, or coexistence of these. Examples thereof include a graft polymer obtained by polymerizing a vinyl-based monomer below.

The content of the binder resin is, for example, preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and 60% by mass or more and 85% by mass or less with respect to the entire toner particles. More preferred.

-Colorant-
Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzine yellow, slene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolon orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmin 6B, Dupont Oil Red, Pyrazolon Red, Lissole Red, Rhodamin B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultra Marine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malakite green oxalate, aclysine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindico-based, dioxazine-based, thiazine-based, azomethine-based, indico-based, phthalocyanine-based, aniline black Various dyes such as system, polymethine system, triphenylmethane system, diphenylmethane system, thiazole system and the like can be mentioned.
The colorant may be used alone or in combination of two or more.

As the colorant, a surface-treated colorant may be used or may be used in combination with a dispersant, if necessary. Further, a plurality of kinds of colorants may be used in combination.

The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Release agent-
Examples of the release agent include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; ester waxes such as fatty acid esters and montanic acid esters. ; And so on. The release agent is not limited to this.

The melting temperature of the release agent is preferably 50 ° C. or higher and 110 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) by the "melting peak temperature" described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring the transition temperature of plastics". ..

The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Other additives-
Examples of other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as an internal additive.

-Characteristics of toner particles-
In the infrared absorption spectrum analysis, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.6 or less (preferably 0.5 or less, more preferably 0.48 or less). The ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.4 or less (preferably 0.3 or less, more preferably 0.2 or less).
As described above, when the polyhydric alcohol component in the amorphous polyester resin as the binder resin does not contain or contains a small amount of the alkylene oxide adduct of bisphenol A, the toner particles absorb this infrared ray. Has spectral characteristics.

On the other hand, from the viewpoint of the storage stability of the toner, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.2 or more (preferably 0.3 or more). The ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is preferably 0.05 or more (preferably 0.08 or more).

Further, from the viewpoint of the strength of the toner particles, the ratio of the absorbance of the wave number of 820 cm ^-1 to the absorbance of the wave number of 1500 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.5 or less (preferably 0.4 or less, more preferably. Is preferably 0.35 or less).
On the other hand, from the viewpoint of toner storage stability, the ratio of the absorbance of wave number 820 cm ^-1 to the absorbance of wave number 1500 cm ^-1 in the infrared absorption spectrum analysis of toner particles is 0.1 or more (preferably 0.15 or more). It should be.

Here, the measurement of the absorbance of each wave number by infrared absorption spectrum analysis is measured by the following method. First, a measurement sample is prepared for the toner particles (or toner) to be measured by the KBr tablet method. Then, for the measurement sample, an infrared spectrophotometer (manufactured by JASCO Corporation: FT-IR-410) is used to integrate 300 times, and the wave number is 500 cm ^-1 or more and 4000 cm ^-1 or less under the condition of resolution 4 cm ^-1 . Measure the range of. Then, baseline correction is performed on the offset portion or the like where there is no absorbed light, and the absorbance of each wave number is obtained.

When the weight average molecular weight is Mw and the number average molecular weight is Mn in the GPC measurement of the THF-soluble content of the toner particles, the Mw is 10,000 or more and 60,000 or less (preferably 25,000 or more and 50,000 or less, more preferably 30,000 or more and 48,000 or less). Mw / Mn is 5 or more and 10 or less (preferably 6 or more and 8 or less, more preferably 6.2 or more and 7.8 or less).

As described above, when the toner particles satisfy the above molecular weight characteristics, even if the toner containing the amorphous polyester resin in the toner particles without using the alkylene oxide adduct of bisphenol A or using a small amount is applied, the fixing image is displayed. Fixability is improved.

The peak molecular weight of the molecular weight distribution curve obtained by GPC measurement of the THF-soluble content of the toner particles is preferably 7,000 or more and 11,000 or less, more preferably 8,000 or more and 11,000 or less, and further preferably 8200 or more and 10500 or less.
When the peak molecular weight is within the above range, the fixability of the fixed image is likely to be improved even if the toner containing the amorphous polyester resin containing the amorphous polyester resin in the toner particles without using the alkylene oxide adduct of bisphenol A or using a small amount is applied. ..

The peak molecular weight of the molecular weight distribution curve obtained by GPC measurement of the THF-soluble content of the toner particles indicates the molecular weight of the largest peak when there are a plurality of peaks in the molecular weight distribution curve.

Here, the molecular weight distribution curve, each average molecular weight, and the peak molecular weight in the GPC measurement of the THF-soluble content of the toner particles are measured as follows.
First, 0.5 mg of toner particles (or toner) to be measured are dissolved in 1 g of THF (tetrahydrofuran), ultrasonically dispersed, and then adjusted so that the concentration becomes 0.5%, and this dissolved component is added. Measured by GPC.
"HLC-8120GPC, SC-8020 (manufactured by Tosoh)" is used as a GPC apparatus, two "TSKgel, SuperHM-H (manufactured by Tosoh 6.0 mm ID x 15 cm)" are used as columns, and THF is used as an eluent. As the experimental conditions, the experiment is carried out using a sample concentration of 0.5%, a flow velocity of 0.6 ml / min, a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an RI (Refractive Index) detector. The calibration curve is "polystylele standard sample TSK standard" manufactured by Tosoh: "A-500", "F-1", "F-10", "F-80", "F-380", "A-2500". , "F-4", "F-40", "F-128", "F-700" 10 samples.

The toluene insoluble content of the toner particles is preferably 25% by mass or more and 45% by mass or less, more preferably 28% by mass or more and 38% by mass or less, and further preferably 30% by mass or more and 35% by mass or less.
When the toluene insoluble content of the toner particles is within the above range, the hygroscopicity of the toner particles is lowered, and the transferability of the toner image is easily improved.

Here, the toluene-insoluble component of the toner particles is a component of the toner particles insoluble in toluene. That is, the toluene insoluble component is an insoluble component containing a component of the binder resin insoluble in toluene (particularly, a high molecular weight component of the binder resin) as a main component (for example, 50% by mass or more of the whole). This toluene insoluble content can be said to be an index of the content of the crosslinked resin contained in the toner.

The toluene insoluble content shall be the value measured by the following method.
1 g of the weighed toner particles (or toner) is put into a weighed glass fiber cylindrical filter paper and attached to the extraction tube of a heated Soxhlet extractor. Then, toluene is poured into the flask and heated to 110 ° C. using a mantle heater. Further, the peripheral portion of the extraction tube is heated to 125 ° C. using a heating heater attached to the extraction tube. Extraction is performed at a reflux rate such that the extraction cycle is once in the range of 4 minutes or more and 5 minutes or less. After extraction for 10 hours, the cylindrical filter paper and toner residue are taken out, dried and weighed.
Then, the formula: toner particle (or toner) residue amount (mass%) = [(cylindrical filter paper amount + toner residue amount) (g) -cylindrical filter paper amount (g)] ÷ toner particle (or toner) mass (g) × The toner particle (or toner) residue amount (mass%) is calculated based on 100, and the toner particle (or toner) residue amount (mass%) is defined as a toluene insoluble content (mass%).
The toner particle (or toner) residue is composed of an inorganic substance such as a colorant and an external additive, a high molecular weight component of the binder resin, and the like. Further, when the toner particles contain a mold release agent, the mold release agent is a toluene-soluble component because the extraction is performed by heating.

The toluene insoluble content of the toner particles is, for example, in a binder resin, 1) a method of adding a cross-linking agent to a polymer component having a reactive functional group at the terminal to form a cross-linked structure or a branched structure, and 2) at the end. It is adjusted by a method of forming a crosslinked structure or a branched structure by polyvalent metal ions in a polymer component having an ionic functional group, 3) an extension of the resin chain length by treatment with isocyanate, a method of forming a branch, and the like.

The toner particles may be toner particles having a single layer structure, or may be toner particles having a so-called core-shell structure composed of a core portion (core particles) and a coating layer (shell layer) covering the core portion. You may.
Here, the toner particles having a core-shell structure include, for example, a core portion composed of a binder resin and, if necessary, other additives such as a colorant and a mold release agent, and a binder resin. It is preferable that it is composed of a coated layer and.

The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

The various average particle sizes and various particle size distribution indexes of the toner particles were measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolytic solution was measured using ISOTON-II (manufactured by Beckman Coulter). Toner.
At the time of measurement, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant. This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolytic solution in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm or more and 60 μm or less is obtained by using an aperture with an aperture diameter of 100 μm by the Coulter Multisizer II. Measure. The number of particles to be sampled is 50,000.
Draw a cumulative distribution of volume and number from the small diameter side for each particle size range (channel) divided based on the measured particle size distribution, and the particle size to be cumulative 16% is volume particle size D16v, number particle size. The particle size having a cumulative particle size of D16p and a cumulative total of 50% is defined as a volume average particle size D50v and a cumulative number average particle size D50p, and a particle size having a cumulative number of 84% is defined as a volume particle size D84v and a number particle size D84p.
Using these, the volume particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 , and the number particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

The average circularity of the toner particles is obtained by (circumferential peripheral length) / (peripheral length) [(circumferential length of a circle having the same projected area as the particle image) / (peripheral length of the particle projected image)]. Specifically, it is a value measured by the following method.
First, a flow-type particle image analyzer (Sysmex) that captures a particle image as a still image by sucking and collecting toner particles to be measured, forming a flat flow, and instantly emitting strobe light, and analyzing the particle image. Obtained by FPIA-3000) manufactured by the company. The number of samplings for obtaining the average circularity is set to 3500.
When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additive has been removed. ..

(External agent)
Examples of the external additive include inorganic particles. As the inorganic particles, SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO. _Examples thereof include SiO ₂ , K ₂ O · (TiO ₂ ) n, Al ₂ O 3.2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , _Л4 and the like.

The surface of the inorganic particles as an external additive should be hydrophobized. The hydrophobizing treatment is performed, for example, by immersing the inorganic particles in the hydrophobizing agent. The hydrophobizing agent is not particularly limited, and examples thereof include a silane-based coupling agent, a silicone oil, a titanate-based coupling agent, and an aluminum-based coupling agent. These may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

Examples of the external additive include resin particles (resin particles such as polystyrene, polymethylmethacrylate (PMMA), and melamine resin), cleaning active agents (for example, metal salts of higher fatty acids typified by zinc stearate, and fluoropolymers). Particles) and the like.

The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less with respect to the toner particles.

(Toner manufacturing method)
Next, a method for manufacturing the toner according to the present embodiment will be described.
The toner according to the present embodiment can be obtained by externally adding an externalizing agent to the toner particles after producing the toner particles.

The toner particles may be produced by any of a dry production method (for example, a kneading and pulverizing method, etc.) and a wet production method (for example, an agglomeration coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The manufacturing method of the toner particles is not particularly limited to these manufacturing methods, and a well-known manufacturing method is adopted.

Then, the toner in the present embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. The mixing may be carried out by, for example, a V blender, a Henschel mixer, a Ladyge mixer or the like. Further, if necessary, coarse particles of toner may be removed by using a vibration sieving machine, a wind sieving machine, or the like.

<Career>
The carrier is not particularly limited, and examples thereof include known carriers. As the carrier, for example, a coating carrier in which the surface of a core material made of magnetic powder is coated with a coating resin; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and blended in a matrix resin; a porous magnetic powder is impregnated with resin. Examples thereof include a resin-impregnated carrier.
The magnetic powder dispersion type carrier and the resin impregnated type carrier may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

Examples of the magnetic powder include magnetic metals such as iron, nickel and cobalt, and magnetic oxides such as ferrite and magnetite.

Examples of the coating resin and matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, and styrene-acrylic acid ester. Examples thereof include a copolymer, a straight silicone resin containing an organosiloxane bond or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenol resin, an epoxy resin and the like.
The coating resin and the matrix resin may contain other additives such as conductive particles.
Examples of the conductive particles include metals such as gold, silver and copper, and particles such as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate and potassium titanate.

Here, in order to coat the surface of the core material with the coating resin, a method of coating with a coating resin and, if necessary, a coating layer forming solution in which various additives are dissolved in an appropriate solvent can be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.
Specific resin coating methods include a dipping method in which the core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the core material surface, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a solution for forming a coating layer is sprayed, a kneader coater method in which a core material of a carrier and a solution for forming a coating layer are mixed in a kneader coater, and a solvent is removed.

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

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

<Manufacturing of amorphous polyester resin>
(Preparation of amorphous polyester resin (A1))
In a three-mouthed flask with a dried inside, 60 parts by mass of dimethyl terephthalate, 74 parts by mass of dimethyl fumarate, 30 parts by mass of dodecenyl succinic anhydride, 22 parts by mass of trimellitic acid, 138 parts by mass of propylene glycol, and 0 parts of dibutyl tin oxide. .. In a nitrogen atmosphere with 3 parts by mass, the water generated by the reaction was removed from the system, reacted at 185 ° C for 3 hours, then gradually reduced in pressure to 240 ° C, and further 4 After reacting for a time, it was cooled. In this way, an amorphous polyester resin (A1) having a weight average molecular weight of 39000 was prepared.

(Preparation of amorphous polyester resin (A2))
After reacting at 190 ° C. for 3 hours, the temperature was raised to 220 ° C. while gradually reducing the pressure, and the reaction was carried out for another 2.5 hours. A polyester resin (A2) was produced. The weight average molecular weight was 26000.

(Preparation of amorphous polyester resin (A3))
Instead of 138 parts by mass of propylene glycol, 128 parts by mass of propylene glycol and 19 parts by mass of butylene glycol were used, and the mixture was reacted at 195 ° C. for 4 hours, then gradually reduced in pressure to 240 ° C. and further reacted for 6 hours. The amorphous polyester resin (A3) was prepared in the same manner as the amorphous polyester resin (A1) except for the above. The weight average molecular weight was 56000.

<Making crystalline resin>
(Preparation of crystalline polyester resin (B1))
First, 100 parts by mass of dimethyl sebacate, 67.8 parts by mass of hexanediol, and 0.10 parts by mass of dibutyl tin oxide were placed in a three-necked flask under a nitrogen atmosphere, and water generated during the reaction was removed from the system. Then, the reaction was carried out at 185 ° C. for 5 hours, the temperature was raised to 220 ° C. while gradually reducing the pressure, the reaction was carried out for 6 hours, and then the mixture was cooled. In this way, a crystalline polyester resin (B1) having a weight average molecular weight of 33700 was prepared.

The melting temperature of this crystalline polyester resin (B1) is described in JIS K7121-1987 "Method for measuring transition temperature of plastic" from the DSC curve obtained by differential scanning calorimetry (DSC). It was 71 ° C. as determined by the "melting peak temperature" of.

<Preparation of reference amorphous polyester resin>
(Reference: Preparation of amorphous polyester resin (C1))
60 parts by mass of dimethyl terephthalate, 74 parts by mass of dimethyl fumarate, 30 parts by mass of dodecenyl succinic acid anhydride, 22 parts by mass of trimellitic acid, 137 parts by mass of bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct. A reference amorphous polyester resin (C1) was produced in the same manner as the amorphous polyester resin (A1) except that the content was 191 parts by mass and 0.3 parts by mass of dibutyl tin oxide. The weight average molecular weight was 27,000.

<Making toner>
(Preparation of toner (1))
73 parts by mass of amorphous polyester resin (A1), 6 parts by mass of crystalline polyester resin (B1), 7 parts by mass of colorant (CI Pigment Red 122), and mold release agent (paraffin wax, melting temperature). Add 5 parts by mass of ester wax (behenyl behenate, Unistar M-2222SL, manufactured by Nichiyu Co., Ltd.) and 2 parts by mass of ester wax (manufactured by Nippon Oil Co., Ltd.) to Henchel Mixer (manufactured by Nippon Coke Industries Co., Ltd.) at 73 ° C. Then, the mixture was stirred and mixed at a peripheral speed of 15 m / sec for 5 minutes, and then the obtained stirring mixture was melt-kneaded with an extruder type continuous kneader.
Here, the setting conditions of the extruder were that the supply side temperature was 160 ° C., the discharge side temperature was 130 ° C., the supply side temperature of the cooling roll was 40 ° C., and the discharge side temperature was 25 ° C. The temperature of the cooling belt was set to 10 ° C.
After cooling the obtained molten kneaded product, it is roughly pulverized using a hammer mill, then finely pulverized to 6.5 μm using a jet crusher (manufactured by Nittetsu Mining Co., Ltd.), and further elbow jet classifier. (Made by Nittetsu Mining Co., Ltd., model: EJ-LABO) was used for classification to obtain toner particles (1). The volume average particle size of the toner particles (1) was 7.0 μm.
Then, 100 parts by mass of the toner particles (1) and 1.2 parts by mass of commercially available fumed silica RX50 (manufactured by Aerosil Japan) as an external additive are used at a peripheral speed of 30 m using a Henshell mixer (manufactured by Mitsui Miike Machinery Co., Ltd.). Mixing was performed under the conditions of / s for 5 minutes to obtain toner (1).

(Preparation of toner (2))
The toner particles (2) were produced in the same manner as the toner particles (1) except that the amorphous polyester resin (A1) was changed to the amorphous polyester resin (A2). The volume average particle size of the toner particles (2) was 6.8 μm.
Then, the toner (2) was obtained in the same manner as the toner (1) except that the toner particles (2) were used.

(Preparation of toner (3))
The toner particles (3) were produced in the same manner as the toner particles (1) except that the amorphous polyester resin (A1) was changed to the amorphous polyester resin (A3). The volume average particle size of the toner particles (3) was 7.5 μm.
Then, the toner (3) was obtained in the same manner as the toner (1) except that the toner particles (3) were used.

(Preparation of toner (4))
The toner particles (4) were produced in the same manner as the toner particles (1) except that the number of copies of the amorphous polyester resin (A1) was changed to 79 parts by mass without using the crystalline polyester resin (B1). .. The volume average particle size of the toner particles (4) was 7.1 μm.
Then, the toner (4) was obtained in the same manner as the toner (1) except that the toner particles (4) were used.

(Preparation of reference toner (C1))
The reference toner particles (C1) were produced in the same manner as the toner particles (4) except that the amorphous polyester resin (A1) was changed to the reference amorphous polyester resin (C1). The volume average particle size of the reference toner particles (C1) was 7.7 μm.
Then, the reference toner (C1) was obtained in the same manner as the toner (1) except that the reference toner particles (C1) were used.

<Preparation of developer>
(Developers (1) to (4), Reference developer (C1))
8 parts by mass of each obtained toner and 100 parts by mass of carriers were mixed to prepare a developer (1) to (4) and a reference developer (C1), respectively.
The carriers consisted of 100 parts by mass of ferrite particles (volume average particle size: 50 μm), 14 parts by mass of toluene, and a styrene-methylmethacrylate copolymer (component ratio: styrene / methylmethacrylate = 90/10, weight average molecular weight Mw). = 80000) First, a coating liquid in which the above components excluding ferrite particles were stirred with a stirrer for 10 minutes to disperse 2 parts by mass was prepared, and then the coating liquid and the ferrite particles were mixed with a vacuum degassing type kneader (= 80000). It was obtained by putting it in a product (manufactured by Inoue Seisakusho), stirring it at 60 ° C. for 30 minutes, degassing it under reduced pressure while further heating it, drying it, and then sieving it at 105 μm.

<Various measurements>
For each toner, the molecular weight characteristics of the toner particles, the infrared absorption spectrum characteristics of the toner particles, and the toluene insoluble content were measured according to the methods described above. The results are shown in Table 1.

<Examples 1 to 4>
-Preparation of image forming apparatus (1) Color1000iPress manufactured by Fuji Xerox Co., Ltd. was prepared as an image forming apparatus. It should be noted that this image forming apparatus is an intermediate transfer type apparatus provided with an intermediate transfer belt. In this image forming apparatus, the configuration of the primary transfer apparatus is provided with the embodiment shown in FIG. 2, that is, the elastic pressing member 162 which is not rotationally driven and presses the intermediate transfer belt 15 from the inner peripheral surface side toward the photoconductor 11. The structure was modified so that the low friction sheet 164 was interposed between the intermediate transfer belt 15 and the elastic pressing member 162.

The intermediate transfer belt 15 was provided with a belt member made of polyimide resin and made semi-conductive by adding carbon black.

The elastic pressing member 162 is an insulating member made of urethane foam rubber, and the surface on the side that presses the intermediate transfer belt 15 is "concave" in a free state where it is not pressed (no external pressure is applied). (That is, the elastic pressing member 162A having the shape shown in FIG. 4) was used. The "micro hardness" of the elastic pressing member 162 and the "maximum length ( _LP ) in the driving direction of the intermediate transfer belt 15" of the elastic pressing member 162 are shown in Table 2 below.

On the low friction sheet 164, a sheet member made of polyimide resin and made conductive by adding carbon black was installed. The thickness of the low friction sheet 164 was 200 μm.

The nip length at the primary transfer position in the image forming apparatus (1) (the length in the driving direction of the intermediate transfer belt 15 in the contact region where the intermediate transfer belt 15 contacts along the photoconductor 11 ( _LN )), and The ratio [L _N / _{L P ×} 100] of the elastic pressing member 162 maximum length (LP) and nip length (L _N ) is shown in Table 2 below.

A developing agent having toners (1) to (4) shown in Table 1 below was housed in the developing device of this image forming device.

<Comparative Examples 1 to 4 and Reference Examples>
Preparation of Image Forming Device (C1) for Comparison In the image forming apparatus (1), the surface on the side that presses the intermediate transfer belt 15 as the elastic pressing member 162 in the primary transfer device is not pressed (external pressure is not applied). An image forming apparatus having the same configuration as the image forming apparatus (1) except that a member having a "convex shape" (that is, an elastic pressing member 162C having the shape shown in FIG. 6) is used in a free state (not provided). (C1) was prepared.
The "micro hardness" of the elastic pressing member 162 and the "maximum length ( _LP ) in the driving direction of the intermediate transfer belt 15" of the elastic pressing member 162 are shown in Table 2 below.

The nip length at the primary transfer position in the image forming apparatus (C1) (length in the driving direction of the intermediate transfer belt 15 in the contact region where the intermediate transfer belt 15 contacts along the photoconductor 11 ( _LN )), and The ratio [L _N / _{L P ×} 100] of the elastic pressing member 162 maximum length (LP) and nip length (L _N ) is shown in Table 2 below.

A developer having toners (1) to (4) or (C1) shown in Table 1 below was housed in the developing apparatus of this image forming apparatus.

<Evaluation>
(Transcribability)
Using the above image forming apparatus, the transferability in a high temperature and high humidity environment (35 ° C., 85%) was evaluated by the following method.
A 100% solid patch was formed on the image holder (photoreceptor), primary transfer was performed on the intermediate transfer belt, and the mass of the patch on the photoconductor and the patch on the intermediate transfer belt was measured. The transfer efficiency (%) was defined as "toner mass on the intermediate transfer belt / toner mass on the photoconductor x 100", and the transferability was evaluated based on the transfer efficiency.
The evaluation criteria are as follows.
A (◎): Transcription efficiency 98% or more B (○): Transcription efficiency 95% or more and less than 98% C (Δ): Transcription efficiency 90% or more and less than 95% D (×): Transcription efficiency less than 90%

From the above results, the maximum length of the elastic pressing member ( _LP ) is based on the elastic pressing member in which the surface on the side that presses the intermediate transfer belt is "concave" in the free state where the specific toner is used and the intermediate transfer belt is not pressed. In the image forming apparatus of the embodiment in which the ratio [L _N / L _P × 100] of the nip length to the nip length (L _N ) is 50% or more and 98% or less, the surface on the side that presses the intermediate transfer belt presses. Using an elastic pressing member that is "convex" in the free state, the ratio [L _N / L _P x 100] of the maximum length ( _{LP) of the elastic pressing member to the nip length (L N )} is 50%. It can be seen that higher transferability of the toner image can be obtained even in a high temperature and high humidity environment as compared with the image forming apparatus of the comparative example in which the number is less than.

The image forming apparatus of the reference example is an example in which a toner containing an amorphous polyester resin using an alkylene oxide adduct of bisphenol A is applied. Then, in the image forming apparatus of the reference example, an elastic pressing member whose surface on the side that presses the intermediate transfer belt is "convex" in a free state without pressing is used, and the maximum length of the elastic pressing member ( _LP ). It can be seen that even when the ratio [L _N / L _P × 100] between the nip length and the nip length (L _N ) is less than 50%, the transferability of the toner image is unlikely to deteriorate.

1Y, 1M, 1C, 1K Image forming unit 11 Photoreceptor (image holder)
12 Charger 13 Laser exposure device 14 Developer 15 Intermediate transfer belt (belt member)
16 Primary transfer device (transfer means)
17 Photoreceptor cleaner 20 Secondary transfer unit 22 Secondary transfer roll 25 Back roll 26 Power supply roll 31 Drive roll 32 Support roll 33 Tension application roll 34 Cleaning Back roll 35 Intermediate transfer belt cleaner 40 Control unit 42 Reference sensor 43 Image density sensor 50 Paper storage section 51 Paper feed roll 52 Transport roll 53 Transport guide 55 Transport belt 56 Fixing inlet guide 60 Fixing device 100, 200 Image forming device 162 Elastic pressing member (pressing member)
164 Low friction sheet (seat member)
201BK, 201C, 201M, 201Y Photoreceptor (image holder)
202BK, 202C, 202M, 202Y Charger 203BK Black developing device 203C Cyan developing device 203M Magenta developing device 203Y Yellow developing device 204BK, 204C, 204M, 204Y Photoreceptor cleaning member 206 Belt support roll 207 Paper transport belt (belt member)
208 Paper transfer roll 210 Fixing device 212 Cleaning blade 213 Cleaning facing roll 214BK, 214C, 214M, 214Y Exposed device 215 Paper (recording medium)
216BK, 216C, 216M, 216Y Transfer device (transfer means)
220 Paper Conveyor Belt Cleaning Equipment

Claims (16)

Image holder and
A charging means for charging the surface of the image holder, and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The binder resin contains an amorphous polyester resin, and when the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles, Mw is 10,000 or more and 60,000 or less. Mw / Mn is 5 or more and 10 or less, and the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, ^and the wave number 720 cm-. An electrostatic charge image developer having a toner containing toner particles having a molecular weight 820 cm- ¹ absorbance ratio of ¹ to an absorbance of 0.4 or less is contained, and the electrostatic charge image developer is applied to the surface of the image holder. A developing means for developing the formed electrostatic charge image as a toner image, and
A belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and the surface on the side that presses the belt member is an elastic body. Yes, the surface on the side that presses the belt member is flat or concave in a state where the belt member is not pressed, has a pressing member that is not driven to rotate, and is a toner formed on the surface of the image holder. A transfer means for transferring an image to the surface of a recording medium,
An image forming apparatus. Image holder and
A charging means for charging the surface of the image holder, and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
The binder resin contains an amorphous polyester resin, and when the weight average molecular weight is Mw and the number average molecular weight is Mn in the gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles, Mw is 10,000 or more and 60,000 or less. Mw / Mn is 5 or more and 10 or less, and the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.6 or less, ^and the wave number 720 cm-. An electrostatic charge image developer having a toner containing toner particles having a molecular weight 820 cm- ¹ absorbance ratio of ¹ to an absorbance of 0.4 or less is contained, and the electrostatic charge image developer is applied to the surface of the image holder. A developing means for developing the formed electrostatic charge image as a toner image, and
A belt member whose outer peripheral surface comes into contact with the image holder, and a pressing member that presses the belt member from the inner peripheral surface side toward the image holder, and the surface on the side that presses the belt member is an elastic body. The belt member of the pressing member, which has a pressing member that is not driven to rotate and has a length ( _LN ) in the driving direction of the belt member in a contact region where the belt member comes into contact with the image holder. The ratio [ _LN / _{LP ×} 100] to the maximum length (LP) in the driving direction is 50% or more and 98% or less, and the toner image formed on the surface of the image holder is the surface of the recording medium. And the transfer means to transfer to
An image forming apparatus. In the infrared absorption spectrum analysis of the toner particles, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.5 or less, and the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is The image forming apparatus according to claim 1 or claim 2, which is 0.3 or less. In the infrared absorption spectrum analysis of the toner particles, the ratio of the absorbance of the wave number 1500 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is 0.2 or more, and the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 720 cm ^-1 is The image forming apparatus according to any one of claims 1 to 3, which is 0.05 or more. The image formation according to any one of claims 1 to 4, wherein the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 1500 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.5 or less. Device. The image forming apparatus according to claim 5, wherein the ratio of the absorbance of the wave number 820 cm ^-1 to the absorbance of the wave number 1500 cm ^-1 in the infrared absorption spectrum analysis of the toner particles is 0.4 or less. The image forming apparatus according to any one of claims 1 to 6, wherein the peak molecular weight of the molecular weight distribution curve obtained by gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles is 7000 or more and 11000 or less. .. The image forming apparatus according to claim 7, wherein the peak molecular weight of the molecular weight distribution curve obtained by gel permeation chromatography measurement of the tetrahydrofuran-soluble component of the toner particles is 8000 or more and 11000 or less. The image forming apparatus according to any one of claims 1 to 8, wherein the toluene insoluble content of the toner particles is 28% by mass or more and 38% by mass or less. The image forming apparatus according to claim 9, wherein the toluene insoluble content of the toner particles is 30% by mass or more and 35% by mass or less. The image forming apparatus according to any one of claims 1 to 10, wherein the toner particles contain a crystalline resin. The image forming apparatus according to claim 11, wherein the content of the crystalline resin is 3% by mass or more and 20% by mass or less with respect to the total amount of the toner. The image forming apparatus according to claim 12, wherein the content of the crystalline resin is 5% by mass or more and 15% by mass or less with respect to the total amount of the toner. The image forming apparatus according to any one of claims 1 to 13, wherein the belt member is an intermediate transfer belt. The image forming apparatus according to any one of claims 1 to 14, wherein the transfer means is interposed between the belt member and the pressing member with a sheet member. The image forming apparatus according to any one of claims 1 to 15, wherein the micro-hardness of the elastic body is 20 degrees or more and 60 degrees or less.

Images