JP2006119594A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method using a conductive fur brush which increases transfer efficiency and can suppress scuffing and wear of a photoreceptor surface and image blurring in a high humidity environment over a prolonged period of time. <P>SOLUTION: The image forming method includes at least a charge regulating step of regulating the charged state of residual toner after temporarily recovering the residual toner, by the conductive fur brush, which remains on a surface of a latent image carrier after transferring a toner image and which has been charged to a polarity reverse to the polarity of toner supplied from a developing means, and a toner recovering step of recovering the residual toner by the developing means after discharging the residual toner recovered by the conductive fur brush onto the surface of the latent image carrier, wherein the residual toner recovered by the conductive fur brush is discharged onto the surface of the latent image carrier after reversing the polarity by the conductive fur brush. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method and an image forming apparatus using electrophotography.

  Conventionally, an image is formed by electrophotography, in which the surface of a latent image carrier is charged and exposed to develop an electrostatic latent image produced with colored toner to produce a toner image, and the toner image is transferred to a transfer paper or the like. This is performed by fixing this with a heat roll or the like to form an image. Untransferred toner, discharge products generated by the charging process, and the like remain on the surface of the latent image carrier (hereinafter sometimes referred to as “photosensitive member”) after the transfer process. Therefore, a cleaning process for removing these residues prior to the next image forming process is required.

  As such a cleaning process, the method of bringing a rubber blade into contact with the photosensitive member is most widely used because it is simple. However, in the cleaning unit, stress is generated due to friction between the surface of the photoreceptor and the cleaning blade. For this reason, when an organic photoconductor is used, the surface of the photoconductor is worn and scratched.

  In order to improve these, there is a method in which a protective layer having a high hardness is provided on the outermost layer of the organic photoconductor, or a hard photoconductor such as amorphous silicon is used that is not easily damaged. In addition, in order to obtain a good image quality over a long period of time, it is necessary to prevent not only the photoreceptor surface deterioration but also the cleaning member deterioration. However, when such a high-hardness photoconductor is used, wear and scratches on the surface of the photoconductor are reduced, but wear of a rubber blade used for a cleaning blade (hereinafter sometimes referred to as “blade”) is accelerated. Therefore, there arises a problem that the cleaning of the blade and the deposit cannot be removed due to the deterioration of the blade.

On the other hand, it is desirable that there is no waste toner in terms of environmental protection and effective use of resources. For example, a waste toner-less system in which toner generated after transfer is collected by a cleaner unit composed of a blade or the like and returned to the developing machine for reuse. Has been proposed. However, there is a problem that a transport mechanism such as an auger must be attached and the apparatus becomes large.

  On the other hand, the toner remaining on the surface of the photoconductor after the transfer process in which the toner image is transferred from the photoconductor to a transfer medium such as an intermediate transfer body or a recording medium without using a member such as a blade. A cleaner-less system that collects residual toner) at the same time as developing with a developing machine is a method that can save space and waste toner. In this method, the toner cleaning mechanism is based on a bias that is applied to the developing roll in the developing machine and the residual toner charged in a normal polarity (polarity when toner is supplied from the developing machine to the surface of the photoreceptor) It is returned to the developing device side by the potential difference with the background in the body background portion.

  However, the residual toner present on the surface of the photoreceptor after the transfer process receives a discharge history during the transfer process, and the polarity of some of the residual toner is reversed (reversed) to the normal polarity. The negatively polarized residual toner continues to remain on the surface of the photoconductor without being collected by the developing machine, which may cause an obstacle in the exposed area, or if a contact charger is used, it may adhere to the charger and cause a charging fault. In addition, problems such as toner fusing to the surface of the photoreceptor due to repeated contact with a contact member such as a charger or a transfer member.

In order to avoid such troubles due to the reverse-polarized residual toner, the charged state of the reverse-polarized residual toner after the transfer is again obtained using a charge adjusting member such as a conductive rubber roller, a conductive fur brush, or a magnetic brush. A method of adjusting to a normal polarity has been proposed. This method has an advantage that a cleaning device / process for directly cleaning the surface of the photosensitive member with a cleaning blade or the like is unnecessary (cleanerless).
However, in the formation of a color image, when the toner images of the respective colors are sequentially superimposed and transferred, the toner image corresponding to the already formed / transferred color is subjected to a discharge history during the transfer process and receives a strong reverse polarity. Shows chargeability. For this reason, when the charge adjusting member is not in contact with the surface of the photosensitive member, it is not in contact, so that the charge adjusting ability with respect to the reverse-polarized residual toner is insufficient, and it is difficult to reverse the normal polarity again. It is.

  In the case where the charge adjusting member is a contact type conductive rubber roller, if the toner held on the surface of the conductive rubber roller is rubbed against the photoconductor for a long period of time, the toner tends to be fused to the photoconductor, and particularly the fixability is improved. In the case of a toner using a binder resin having a low glass transition temperature for improvement, it becomes more remarkable. In order to avoid such a problem, a porous conductive sponge roller may be used, but the conductive sponge roller has a problem that stable performance cannot be maintained for a long period of time.

  In order to solve such problems, the reverse polarity toner after the post-transfer process is temporarily held by a brush-type charge adjusting member (conductive fur brush), adjusted to a regular polarity charge, and developed during development. A method of gradually returning to the developing machine has been proposed (see Patent Document 1). When a conductive fur brush is used, the toner charge adjustment performance is good and the toner retainability is good, and even if the toner is held on the conductive fur brush for a long period of time, the stress applied to the toner is small. The problem of fusing is also avoided.

However, in the conductive fur brush, the tip of the brush fiber locally wears the same part of the surface of the photoconductor, so that when using an organic photoconductor, deep scratches are generated on the photoconductor and stable for a long time. It is difficult to ensure the performance. However, when an organic photoreceptor having a high surface is used, it is possible to suppress wear and scratches on the surface of the photoreceptor even when a conductive fur brush is used.
On the other hand, in a charging method using a contact-type charging roll on which an alternating electric field is superimposed that can obtain uniform charging of the surface of the photoreceptor without ozone, discharge products are generated on the surface of the photoreceptor due to discharge. For this reason, if discharge products cannot be removed from the surface of the photoreceptor, white spots and image blurring occur due to moisture leakage in a high humidity environment.

Accordingly, when a photoconductor having a high surface strength is used, wear and scratches are improved, but discharge products and the like are not sufficiently removed, and white spots and image blurring are problematic in a high humidity environment.
In order to improve wear and scratches, and to prevent white spots and image blurring in a high-humidity environment, for example, the charging process is an injection charging method, and an organic photoreceptor having a high hardness and low friction is used. A cleanerless method for preventing photoconductor scratches (see Patent Document 2). However, the injection charging method has a very special configuration in which conductive fine particles are dispersed in the outermost layer of the photoconductor, so that a general-purpose photoconductor cannot be used.

In addition to this, a magnetic brush as a charger and a photoreceptor containing a siloxane resin whose surface layer has a cross-linked structure in order to increase the surface hardness as a photoreceptor are used in combination, and the saturated water content in the toner There is also a cleanerless method that prevents the occurrence of abrasion and scratches on the surface of the photoreceptor and image blurring in a high-humidity environment by adjusting to a specific range (see Patent Document 3).
However, in the injection charging method using a magnetic brush charger, good charging cannot be obtained unless the surface resistance of the outermost surface layer of the photosensitive member is adjusted by dispersing conductive fine particles in the outermost layer of the photosensitive member. Further, when a general-purpose photoconductor having a high surface resistance is used, it is difficult to charge the toner, and it is considered that uniform charging becomes difficult as the contamination of the magnetic brush with the residual toner proceeds.
JP 2001-188416 A JP 2001-194810 A JP 2001-265041 A

  An object of the present invention is to solve the above problems. That is, the present invention provides an image forming method using a conductive fur brush that improves the transfer efficiency and can suppress the occurrence of scratches and abrasion on the surface of the photoreceptor and the occurrence of image blurring and white spots in a high humidity environment over a long period of time. It is another object of the present invention to provide an image forming apparatus using the same.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
A charging step of charging the surface of the latent image carrier, a latent image forming step of irradiating the charged surface of the latent image carrier with light to form a latent image, and a developer containing toner supplied from the developing means. A developing step of developing the latent image to form a toner image; a transferring step of transferring the toner image to a transfer target; and a surface of the latent image carrier after the toner image is transferred; A residual toner charged to a polarity opposite to the polarity of the supplied toner is temporarily collected by a conductive fur brush to adjust the charging state, and the residual toner collected by the conductive fur brush is removed from the latent toner. A toner recovery step of discharging to the surface of the image carrier and recovering by a developing means,
An image forming method for discharging the residual toner collected by the conductive fur brush to the surface of the latent image carrier after reversing its polarity by the conductive fur brush,
The latent image carrier surface contains a resin having a crosslinked structure, and the toner contains spherical inorganic fine powder and / or organic fine powder having an average particle diameter in the range of 50 nm to 200 nm. It is a forming method.

<2>
The image forming method according to <1>, wherein the surface of the latent image carrier contains a compound having a charge transporting ability.

<3>
<1> or characterized in that the resin having a crosslinked structure is at least one resin selected from a phenolic resin obtained by crosslinking a phenol derivative having a methylol group and a siloxane resin having a crosslinked structure. The image forming method according to <2>.

<4>
<3, wherein the resin having a crosslinked structure includes a structural unit having a charge transporting ability including at least one selected from a hydroxyl group, a carboxyl group, an alkoxysilyl group, an epoxy group, a thiol group, and an amino group. >.

<5>
The image forming method according to any one of <1> to <4>, wherein a shape factor SF of the toner defined by the following formula (1) is in a range of 100 to 140.
Formula (1) SF = 100 × π × ML ² / 4A
[In the formula (1), SF represents the shape factor of the toner, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles. ]

<6>
A latent image carrier comprising a resin having a crosslinked structure on the surface, a charging means for charging the surface of the latent image carrier, and a latent image for forming a latent image by irradiating the charged surface of the latent image carrier with light. Forming means; developing means for developing the latent image with a developer containing toner to form a toner image; transfer means for transferring the toner image to a transfer target; and the latent image after transferring the toner image. A conductive fur brush that has at least a function of collecting the residual toner remaining on the surface of the carrier and charged to a polarity opposite to the polarity of the toner supplied from the developing unit and adjusting the charged state, <1> An image forming apparatus that forms an image by using the image forming method according to any one of to <5>.

  As described above, according to the present invention, the conductive fur brush can improve the transfer efficiency and can suppress the occurrence of scratches and abrasion on the surface of the photoconductor and image blurring and white spots under a high humidity environment over a long period of time. And an image forming apparatus using the image forming method.

-Image forming method-
The image forming method of the present invention comprises a charging step for charging the surface of a latent image carrier (photoreceptor), a latent image forming step for forming a latent image by irradiating the charged latent image carrier surface with light, A developing step of developing the latent image with a developer containing toner supplied from a developing unit to form a toner image; a transferring step of transferring the toner image to a transfer target; and a latent step after transferring the toner image. A charge adjusting step for temporarily collecting the residual toner remaining on the surface of the image carrier and charged to a polarity opposite to the polarity of the toner supplied from the developing unit with a conductive fur brush, and adjusting the charged state; At least a toner recovery step of discharging the residual toner recovered by the fur brush onto the surface of the latent image carrier and recovering the residual toner by a developing unit, and the residual toner recovered by the conductive fur brush An image forming method wherein the polarity is reversed by a conductive fur brush and then discharged onto the surface of the latent image carrier, wherein the surface of the latent image carrier contains a resin having a crosslinked structure, and the toner has an average It includes spherical inorganic fine powder and / or organic fine powder having a particle size in the range of 50 nm to 200 nm.

In the image forming method of the present invention, the residual toner that has been reverse-polarized after the post-transfer step is temporarily transferred by a conductive fur brush to which a bias having a polarity opposite to (normal) polarity of the toner supplied from the developing unit is applied. By being collected and held, the charged state is adjusted again to the normal polarity and then discharged again to the surface of the latent image carrier.
For this reason, the residual toner charged from the reverse polarity to the normal polarity again is collected by the developing means by the potential difference between the bias applied to the developing roll in the developing machine and the background in the photosensitive member background portion.
The electrically conductive fur brush for charge adjustment temporarily holds the reversely-polarized residual toner, and is positively formed by gap discharge between the brush tip of the electrically conductive fur brush and the latent image carrier. In order to maintain the charging performance of the conductive fur brush, a cleaning cycle may be provided in which the residual toner staying in the conductive fur brush is periodically discharged to the surface of the latent image carrier when not developed.

In the image forming method of the present invention, although a conductive fur brush that damages or wears the surface of the photoconductor is used, the surface of the photoconductor includes a resin having a cross-linked structure. Further, since the wear resistance is improved, the deterioration of the photoreceptor can be suppressed, and the stable performance can be maintained for a long time.
On the other hand, since the surface of the photoconductor is high in intensity, discharge products adhere to and accumulate on the surface of the photoconductor due to the charging means used for charging. It becomes more prominent when a roll is used. Although this discharge product is removed to some extent by the rubbing effect by the magnetic brush in the developing machine in addition to the rubbing effect by the conductive fur brush, it cannot be removed sufficiently, resulting in the occurrence of image blurring and white spots. Sometimes it ends up.

For this reason, in order to prevent image blurring and white spots, it is considered that the most direct method is to further improve the discharge product removal capability with a conductive fur brush or magnetic brush.
Here, in order to improve the removal capability of the discharge product by the conductive fur brush, that is, the rubbing capability, for example, a method of increasing the flocking density of the fur brush or using hair having a high Young's modulus can be performed. . However, when the rubbing ability of the conductive fur brush is excessively increased, the toner or an external additive added to increase the fluidity of the toner is rubbed against the photoconductor to cause filming.
Further, in order to improve the discharge product removal capability by the magnetic brush of the developing machine, that is, the rubbing capability, the relative peripheral speed difference between the developer carrying member and the photosensitive member is increased, or the developer carrying member is increased. A method of increasing the developer density at the nip portion (development nip) between the toner and the photoreceptor can be used. However, simply increasing the rubbing ability of the magnetic brush in this way causes the toner image developed by the magnetic brush to be disturbed, causing image quality deterioration.
From the above, in order to prevent image blurring and white spots, further improving the discharge product removal ability (rubbing ability) with a conductive fur brush or magnetic brush can reduce filming and image quality degradation. Because it invites, it is practically difficult.

However, if the present inventors externally add fine particles having a certain shape and particle size to the toner, filming may occur and image quality may be deteriorated. It has been found that the ability to remove discharge products that have been insufficient because improvement cannot be expected can be improved, and the occurrence of image blurring and white spots can be prevented.
The present inventors think that this is because the fluidity of the toner is improved by the external addition of the fine particles. That is, normally, when the magnetic brush contacts the surface of the photoconductor in the development nip, it is considered that the discharge product attached to the surface of the photoconductor is scraped off or the toner adsorbs the discharge product. Here, by improving the fluidity of the toner as described above, the frequency of contact between the surface of the photosensitive member and the toner in the development nip increases, and the effect of scraping off the discharge product attached to the surface of the photosensitive member is increased. And the effect of adsorbing to toner increases. Therefore, it seems that the discharge product removal capability is remarkably improved, and the occurrence of image blurring and white spots can be prevented.

As the above-mentioned fine particles, it is effective to use spherical inorganic fine powder and / or organic fine powder (hereinafter sometimes abbreviated as “spherical fine powder”) having an average particle diameter of 70 nm to 200 nm as the toner. is there. In this case, due to the action of the spherical shape differential, the fluidity of the toner in the development nip is improved, and the discharge product adhering to the surface of the photoreceptor is smoothly removed, and image blurring and white spots occur even in a high humidity environment. Can be suppressed.
It is more preferable to add an abrasive to the toner in order to supplement the rubbing effect by a member rubbing the surface of the photoreceptor such as a conductive fur brush.

  Furthermore, the spherical fine powder reduces toner adhesion and improves fluidity, so that high transfer efficiency can be obtained and at the same time the toner charge is stabilized, so that transfer efficiency and toner recoverability in the toner recovery process are improved. There is an effect to increase. Further, by using a toner having a high sphericity within the range of the shape factor SF of 100 to 140, the transfer efficiency can be stabilized over a long period of time.

-Image forming device-
Next, the configuration of an image forming apparatus using the image forming method of the present invention will be described. The image forming apparatus of the present invention is not particularly limited as long as it is a known electrophotographic image forming apparatus using the image forming method of the present invention. Specifically, the image forming apparatus preferably has the following configuration.
That is, a latent image carrier including a resin having a cross-linked structure on the surface, a charging unit for charging the surface of the latent image carrier, and irradiating the charged surface of the latent image carrier with light to form a latent image. A latent image forming means; a developing means for developing the latent image with a developer containing toner to form a toner image; a transfer means for transferring the toner image to a transfer target; and the toner image after transferring the toner image. A conductive fur brush having at least a function of collecting the residual toner remaining on the surface of the latent image carrier and charged to a polarity opposite to the polarity of the toner supplied from the developing unit and adjusting the charged state. It is preferable. Here, the surface of the latent image carrier of this image forming apparatus contains a resin having a crosslinked structure, and the spherical fine powder described above is necessarily externally added to the toner.

  Note that the image forming apparatus of the present invention may include known members other than those described above. In the case of forming a color image, the image forming apparatus of the present invention includes a rotary system in which a plurality of developing units corresponding to each color are arranged around one latent image carrier, a pair of latent image carriers, and Any of the tandem systems including a number of units including a developing unit corresponding to each color may be used.

Next, a specific example of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a configuration example of an image forming apparatus according to the present invention. In FIG. 1, 100 is an image forming apparatus, 110 is a latent image carrier (photoconductor), 111 is a charging roll, and 112 is an exposure apparatus. 113 is a developing device, 113a is a developing roll (magnetic brush carrier), 113b is a layer regulating member, 114 is a transfer roller, 116 is a conductive fur brush (rotary brush), and 120 is an intermediate transfer belt. The conductive fur brush 116 is a rotating body in which fibers (brushes) extend radially, and can be rotated in the same direction as or in the opposite direction to that of the photosensitive member 110. However, the polarity of the reverse-polarized toner described later is efficient. The reverse direction is preferable in that it can be reversed.
The image forming apparatus 100 includes a charging roll 111, an exposure device 112, a developing device 113, a transfer roller 114, a conductive fur, in a clockwise direction along the periphery of the latent image carrier 110 that can rotate in the direction of arrow A in FIG. A brush 116 is disposed. Further, the latent image carrier 110 and the transfer roller 114 are in contact with each other with the intermediate transfer belt 120 interposed therebetween to form a primary transfer portion. Further, a developing roll 113 a is provided in the developing unit 113 at a position facing the latent image carrier 110, and a magnetic brush (not shown) formed on the surface of the developing roll 113 a is a developing roll of the developing unit 113. The magnetic brush density is adjusted by a layer regulating member 113b provided at a position close to 113a.

  Next, an image forming process by the image forming apparatus 100 will be described. First, the surface of the latent image carrier 110 rotating in the direction of arrow A is charged by the charging roller 111. Subsequently, a latent image is formed on the surface of the charged latent image carrier 110 by being exposed to light corresponding to image information irradiated from the exposure device 112. Next, the latent image is developed with a developer supplied from the developing device 113 to form a toner image. In addition, the polarity (normal polarity) of the toner at the time of development can be selected to be negative, for example (hereinafter, description will be made on the assumption that the normal polarity is negative).

  The toner image formed on the surface of the latent image carrier 110 is transferred to the intermediate transfer belt 120 in the primary transfer portion, and is fixed on a recording medium such as paper by a fixing unit (not shown). Incidentally, in the toner (residual toner) that remains on the surface of the latent image carrier 110 without being transferred to the intermediate transfer body 120 at the time of transfer, a polarity (reverse to the normal polarity) due to the bias applied to the transfer roll 114 ( Residual toner (reversed polarity toner) is generated on the positive electrode).

After the transfer of the toner image, the surface of the latent image carrier 110 is captured and collected by the conductive fur brush 116 so as to prepare for the next image formation.
Note that at least a DC voltage (negative voltage) opposite to the polarity of the reverse polarity toner is applied to the conductive fur brush 116, and an AC voltage may be superimposed and applied thereto. It is necessary that a sufficient voltage is applied to recharge to a reverse polarity. As a result, the reverse polarity toner captured and collected by the conductive fur brush 116 can be recharged to a normal polarity by the conductive fur brush 116 having its polarity reversed. Thereafter, the reverse-polarized toner recharged to the normal polarity is discharged to the surface of the latent image carrier 110 again, and together with the residual toner that has not been reverse-polarized, the development disposed on the surface of the latent image carrier 110 and the developing device 113. Using the potential difference with the roll (magnetic brush) 113a, it is collected by the developing unit 113.

  As described above, in the image forming apparatus 100, the residual toner (reversely polarized toner) captured and collected by the conductive fur brush 116 is recharged to the opposite polarity while forming an image, and the latent image carrier is formed. Since the toner is discharged to the surface 110, toner is unlikely to accumulate on the conductive fur brush 116. For this reason, it is not necessary to perform the cleaning of the conductive fur brush 116 itself that involves interruption of image formation (development process) over a long period of time. In addition, the reverse polarity toner generated after the transfer is collected by the conductive fur brush, recharged to the opposite polarity, and then discharged to the surface of the latent image carrier 110, so that the charging roller 111 is contaminated. Problems caused by the polarized toner can be suppressed.

Next, a specific example of an image forming apparatus different from the configuration shown in FIG. 1 will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing another configuration example of the image forming apparatus according to the present invention. In FIG. 2, members having the same functions and configurations as those in FIG. Denotes an image forming apparatus, and 118 denotes a conductive brush (fixed brush).
The image forming apparatus of the present invention, like the image forming apparatus 101 shown in FIG. 2, has a transfer roll 114 disposed around the latent image carrier 110 and conductive with respect to the configuration of the image forming apparatus 100 shown in FIG. A conductive fur brush (fixed brush) 118 may be provided between the fur brush 116 and the fur brush 116 in order to make the residual toner charge adjustment more complete. The conductive fur brush 118 is different from the conductive fur brush 116 in that fibers (brushes) are fixed.
Hereinafter, each part constituting the image forming apparatus of the present invention will be described in more detail.

-Charging means-
As the charging means used in the image forming apparatus of the present invention, a charger using a known charging method can be applied. For example, a charger using a corotron charging system or a contact charging system can be used. In the contact charging method, a roller-shaped charging member, a blade-shaped charging member, a belt-shaped charging member, a brush-shaped charging member, a conductive fur brush-shaped charging member, or the like can be applied. In particular, the roller-shaped charging member and the blade-shaped charging member may be arranged in contact with the latent image carrier or in a non-contact state having a certain amount of gaps (100 μm or less).

A roller-shaped charging member, a blade-shaped charging member, and a belt-shaped charging member are composed of a material adjusted to an effective electrical resistance (10 ³ Ω to 10 ⁸ Ω) as a charging member, You may be comprised from several layers.
The charging member is made of synthetic rubber such as urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM (ethylene-propylene-diene copolymer rubber), epichlorohydrin rubber, polyolefin, polystyrene, vinyl chloride, etc. A material in which an elastomer is used as a main material and an appropriate amount of a conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent is blended can be used. These materials can easily develop an effective electric resistance as a charging member.
Furthermore, a resin such as nylon, polyester, polystyrene, polyurethane, silicone, etc. is made into a paint, and an appropriate amount of any conductivity imparting agent such as conductive carbon, metal oxide, ionic conductive agent, etc. is blended there, and the resulting paint is dipped. They can be laminated and used by any method such as spraying or roll coating.

-Development means-
The developing means used in the image forming apparatus of the present invention preferably uses a contact developing system for collecting toner. A developing brush composed of a carrier and toner is formed on a magnetic brush carrier (developing roll) and developed by bringing it into contact with the latent image carrier, or on a conductive rubber elastic material transporting roll (developing roll). A contact type one-component development system in which toner is attached and the toner is developed on the latent image carrier is suitable. In the case of the two-component development method, the rotation direction of the developing roll may be the same as or opposite to the rotation direction of the latent image carrier, and if a circumferential speed difference is made in the opposite direction to the latent image carrier, The recoverability of the residual toner can be improved. The electric field applied to the developing roll may be a direct current or an alternating current superimposed on the direct current.

In addition, in order to improve the toner recovery property and the discharge product scraping property, the magnetic brush formed on the surface of the developing roll is provided with a layer regulating member so that the density of the magnetic brush facing the photoreceptor is always constant. It is preferable that the magnetic brush density is adjusted within an appropriate range by regulating the layer, and specifically, it is particularly preferable that the relationship expressed by the following formula (2) is satisfied.
Formula (2) 0.75 ≦ ρ / d ≦ 1.5
In equation (2), ρ represents the magnetic brush density (g / m ² ), and d represents the distance (μm) between the developing roll (magnetic brush carrier) and the photosensitive member.

  If ρ / d is less than 0.75, the scraping property of the discharge product is insufficient, and if ρ / d is greater than 1.5, toner clogging occurs especially when the rotation direction of the developing roll is opposite to that of the photoreceptor. As a result, there may be a problem that the carrier falls downward. The developing roll may be in the same direction or in the opposite direction with respect to the rotation direction of the photoconductor, but if the relative speed difference of the magnetic brush with respect to the photoconductor is 100 mm / sec or more, the toner recoverability and the discharge product scraping performance are improved. Since it improves more, it is preferable.

  The bias applied to the developing roll is preferably −50 V to −600 V, more preferably −100 V to −550 V when the normal polarity of the toner is negative. Further, an alternating electric field may be superimposed in order to improve the image quality. The peak-to-peak of this AC voltage is preferably 0.5 kVp-p to 1.5 kVp-p.

-Transfer means-
In addition, as a transfer unit used in the image forming apparatus of the present invention, a transfer unit using a known transfer system can be used. For example, a direct transfer method using a transfer corotron or a transfer roll, an intermediate transfer method using an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer drum, or a latent image carrier that electrostatically adsorbs and conveys a recording material Examples thereof include a transfer means using a transfer belt method for transferring the above image.
In order to improve the transfer efficiency, a peripheral speed difference may be provided between the latent image carrier and the transfer member. The peripheral speed ratio between the latent image carrier and the transfer member is preferably 0.1% to 5%, more preferably 1% to 3%.

-Conductive fur brush-
As shown in FIGS. 1 and 2, the conductive fur brush for adjusting the charging of the toner may be a rotating brush or a fixed brush. In particular, the rotating brush has a toner retaining property and a toner brush for regular cleaning. Excellent release.
It is important that a bias (DC voltage) having the same polarity as the normal polarity of the toner is applied to the conductive fur brush. The bias voltage is preferably in the range of 500V to 1200V in absolute value, and more preferably in the range of 800V to 1200V. When the absolute value of the bias voltage is lower than 500V, it is difficult to adjust the charge of the toner although the toner can be held. In this case, an alternating voltage may be further superimposed and applied.

Nylon, acrylic or polypropylene is preferable as the material for the fibers of the conductive fur brush. Among these, nylon is particularly preferable because of its excellent long-term stability. In order to impart electrical conductivity to the fiber, it is more preferable to knead carbon black. Those blended fibers may be used. The electrical resistance value of the fiber used for the conductive fur brush is preferably 10 ² to 10 ⁵ Ωcm. When the conductive fur brush is a rotating brush, the rotation direction may be the same as or opposite to the rotation direction of the photoconductor.

The fiber density on the surface of the conductive fur brush is preferably 15 × 10 ^{3 to} 120 × 10 ³ fibers / inch ² (23.4 to 186 fibers / mm ² ). The fiber thickness is preferably 2 to 20 denier. The fiber length on the surface of the conductive fur brush (however, the fiber length does not include the thickness of the raised adhesive layer) is preferably 2.5 mm to 7 mm, more preferably 3 mm to 6.5 mm. In the case of a rotating brush, the amount of fibers entering the photoreceptor surface is preferably 0.3 mm to 1.5 mm. The amount of entry means the distance from the surface of the photoreceptor to the tip of the fiber when it is assumed that the fiber has been straightened and stabbed against the surface of the photoreceptor.
By setting the condition of the rotating brush within the above range, there is no damage to the surface of the photoconductor, and the toner charge before entering the contact charger can be adjusted well. Also, when a fixed brush is used as the conductive fur brush, fibers made of the same material as that of the rotating brush can be used.

Further, the image forming apparatus may have only one conductive fur brush, but may have a plurality. In this case, it is preferable to combine a conductive fur brush to which a bias having a polarity opposite to that of the normal polarity of the toner is applied in combination with a conductive fur brush that applies a bias having the same polarity as the normal polarity of the toner.
For example, in the image forming apparatus shown in FIG. 2, a bias having the same polarity as the normal polarity of the toner is applied to the conductive fur brush 116, and a bias having a polarity opposite to the normal polarity of the toner is applied to the conductive fur brush 118. can do.

In rare cases, such as when an image with a low image density is formed in a low humidity environment, the toner charge becomes too high, and the residual toner that is strongly charged to the normal polarity side cannot be completely collected by the developing means as a transfer ghost. May appear in the image. However, transfer ghosts can be prevented by using a plurality of conductive fur brushes composed of the combinations as described above.
Note that in a conductive fur brush to which a bias (DC voltage) having a polarity opposite to the normal polarity of the toner is applied, the absolute value of the bias is preferably in the range of 0 to 400V, and in the range of 200 to 400V. It is more preferable. In this case, an alternating voltage may be further superimposed and applied.

-Latent image carrier (photoconductor)-
Next, the latent image carrier used in the present invention will be described in detail.
The latent image carrier used in the present invention may have a single-layer structure, or may have any known structure such as a laminated structure composed of a charge generation layer and a charge transport layer. The body surface always contains a resin having a crosslinked structure.
FIG. 3 is a schematic cross-sectional view showing a configuration example of a latent image carrier used in the image forming apparatus of the present invention. In FIG. 3, 1 is a latent image carrier (photoconductor), 11 is a conductive substrate, and 12 is a conductive substrate. Represents an undercoat layer, 13 represents a charge generation layer, 14 represents a charge transport layer, 15 represents a protective layer, and 16 represents a photosensitive layer.
The photoreceptor 1 is obtained by laminating an undercoat layer 12, a charge generation layer 13, a charge transport layer 14, and a protective layer 15 in this order on the surface of a conductive substrate 11, and the charge generation layer 13, the charge transport layer 14 and the protective layer 15 are protected. The layer 15 constitutes the photosensitive layer 16. When the latent image carrier has a laminated structure as shown in FIG. 3, the protective layer 15 contains a resin having a crosslinked structure.

As the conductive substrate 11, for example, aluminum formed into a cylindrical shape (drum shape) can be used, but other than this, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold, platinum Metal materials such as metals or alloys such as polyethylene terephthalate, polybutylene terephthalate, polymer materials such as polypropylene, nylon, polystyrene, phenol resin, or conductive materials dispersed in an insulating material such as hard paper or conductive Conductive polymers; conductive metal oxides such as indium oxide; laminates of the above-described conductive materials on insulating materials such as paper and plastic films, etc. can be used. The shape of the conductive substrate 11 may be a sheet shape, a plate shape, or the like.
When the photoreceptor is used in a laser printer, the laser oscillation wavelength is preferably from 350 nm to 850 nm, and the shorter wavelength is preferable because the resolution is excellent.

In order to prevent interference fringes generated when laser light is irradiated, the surface of the conductive substrate 11 is preferably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm. As a roughening method, wet honing is performed by suspending an abrasive in water and spraying on the conductive substrate 11, or the conductive substrate 11 is pressed into contact with a rotating grindstone, and continuous grinding is performed. Centerless grinding, anodizing treatment and the like are preferable.
If Ra is smaller than 0.04 μm, the surface of the conductive substrate 11 is close to a mirror surface, so that the effect of preventing interference cannot be obtained. If Ra is larger than 0.5 μm, the image quality may be rough. When non-interfering light is used as a light source, a roughening treatment for preventing interference fringes is not particularly necessary, and generation of defects due to irregularities on the surface of the conductive substrate 11 can be prevented, which is suitable for a longer life.

  Anodizing treatment is to form an oxide film on an aluminum surface by anodizing in an electrolyte solution using aluminum as an anode. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the intact porous anodic oxide film is chemically active, easily contaminated, and has a large resistance fluctuation due to the environment. Therefore, the pores in the anodized film are sealed with pressurized water vapor or boiling water (a metal salt such as nickel may be added) by volume expansion due to a hydration reaction, and a sealing process is performed to change to a more stable hydrated oxide. .

The thickness of the anodic oxide film is preferably 0.3 to 15 μm. If the thickness is less than 0.3 μm, the barrier property against injection may be poor and the effect may not be sufficient. On the other hand, if it is thicker than 15 μm, the residual potential may increase due to repeated use.
In the case of anodizing using an acidic treatment liquid composed of phosphoric acid, chromic acid and hydrofluoric acid, the following is carried out. First, the mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is such that phosphoric acid is in the range of 10 to 11% by weight, chromic acid is in the range of 3 to 5% by weight, and hydrofluoric acid is in the range of 0.5 to The concentration of these acids is preferably in the range of 13.5 to 18% by weight. The processing temperature is 42 to 48 ° C., but by keeping the processing temperature high, a thicker film can be formed faster. About the film thickness of a film, 0.3-15 micrometers is preferable. When it is thinner than 0.3 μm, the barrier property against injection is poor and the effect is not sufficient. On the other hand, if it is thicker than 15 μm, the residual potential increases due to repeated use.

  The anodizing treatment can be performed by immersing in pure water at 90 to 100 ° C. for 5 to 60 minutes or by contacting with heated steam at 90 to 120 ° C. for 5 to 60 minutes. About the film thickness of a film, 0.1-5 micrometers is preferable. This can be further anodized using an electrolyte solution with low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate. Good.

Further, as shown in FIG. 3, an undercoat layer 12 can be formed between the conductive substrate 11 and the photosensitive layer 16.
Materials used for the undercoat layer 12 include zirconium chelate compounds, zirconium alkoxide compounds, organic zirconium compounds such as zirconium coupling agents, titanium chelate compounds, titanium alkoxide compounds, organic titanium compounds such as titanate coupling agents, aluminum chelate compounds, In addition to organoaluminum compounds such as aluminum coupling agents, antimony alkoxide compounds, germanium alkoxide compounds, indium alkoxide compounds, indium chelate compounds, manganese alkoxide compounds, manganese chelate compounds, tin alkoxide compounds, tin chelate compounds, aluminum silicon alkoxide compounds, Aluminum titanium alkoxide compound, aluminum zirconium alkoxy Compounds, organometallic compounds such as, in particular an organic zirconium compound, an organic titanyl compound, since the organic aluminum compound to residual potential indicates a satisfactory electrophotographic properties lower, are preferably used.

  Also, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-2-methoxyethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyl Triethoxysilane, γ-chloropropyltrimethoxysilane, γ-2-aminoethylaminopropyltrimethoxysilane, γ-mercapropropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, β-3,4-epoxycyclohexyltri It can be used by containing a silane coupling agent such as methoxysilane.

  Furthermore, polyvinyl alcohol, polyvinyl methyl ether, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, polyimide, casein, gelatin, polyethylene, polyester, phenol resin, vinyl chloride- Known binder resins such as a vinyl acetate copolymer, an epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, and polyacrylic acid can also be used.

The mixing ratio of these materials can be appropriately set as necessary. Further, an electron transporting pigment may be mixed / dispersed in the undercoat layer.
Examples of the electron transport pigment include organic pigments such as perylene pigment, bisbenzimidazole perylene pigment, polycyclic quinone pigment, indigo pigment, and quinacridone pigment described in JP-A-47-30330, cyano group, nitro group, Examples thereof include organic pigments such as bisazo pigments and phthalocyanine pigments having electron-withdrawing substituents such as nitroso groups and halogen atoms, and inorganic pigments such as zinc oxide and titanium oxide. Among these pigments, perylene pigments, bisbenzimidazole perylene pigments and polycyclic quinone pigments, zinc oxide, and titanium oxide are preferably used because of their high electron mobility.

  Further, the surface of these pigments may be surface-treated with the above-mentioned coupling agent or binder for the purpose of controlling dispersibility and charge transport property. If the amount of the electron transporting pigment is too large, the strength of the undercoat layer 12 is lowered and a coating film defect is caused. As the mixing / dispersing method, a conventional method using a ball mill, a roll mill, a sand mill, an attritor, an ultrasonic wave, or the like is applied. Mixing / dispersing is carried out in an organic solvent, as long as the organic solvent dissolves a periodical metal compound or resin and does not cause gelation or aggregation when an electron transporting pigment is mixed / dispersed. Anything can be used.

  For example, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene Ordinary organic solvents such as toluene can be used alone or in admixture of two or more. The thickness of the undercoat layer 12 is generally 0.1 to 30 μm, preferably 0.2 to 25 μm.

  As the coating method used when the undercoat layer 12 is provided, conventional methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Can be used. The coated layer is dried to obtain an undercoat layer. Usually, the drying is performed at a temperature at which the solvent can be evaporated to form a film. In particular, the base material that has been subjected to the acidic solution treatment and the boehmite treatment is preferably formed with an intermediate layer because the defect concealing power of the base material tends to be insufficient.

Next, the charge generation layer 13 will be described. As the charge generation material used for the charge generation layer 13, any known charge generation material can be used. For example, azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, perylene pigments, and pyrrolopyrrole. Examples thereof include organic pigments such as pigments and phthalocyanine pigments, and inorganic pigments such as trigonal selenium and zinc oxide.
In particular, inorganic pigments are preferred when a latent image is formed by irradiating the photoreceptor with light having a wavelength of 380 nm to 500 nm, and metal and metal-free phthalocyanine pigments are preferred when light having a wavelength of 700 nm to 800 nm is used.
Among these materials, hydroxygallium phthalocyanine disclosed in JP-A-5-263007 and JP-A-5-279591, chlorogallium phthalocyanine disclosed in JP-A-5-98181, and JP-A-5-140472. And dichlorotin phthalocyanine disclosed in JP-A-5-140473 and titanyl phthalocyanine disclosed in JP-A-4-189873 and JP-A-5-43813 are particularly preferable.

The binder resin used by mixing with the charge generation material can be selected from known insulating resins, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. You can also choose from.
Preferred binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin. Insulating resin such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin can be used, but is not limited thereto. These binder resins can be used alone or in admixture of two or more.

  The blending ratio between the charge generation material and the binder resin (weight ratio) is preferably in the range of 10: 1 to 1:10. In addition, as a method for dispersing these materials, usual methods such as a ball mill dispersion method, an attritor dispersion method, and a sand mill dispersion method can be used. When the charge generating material is a crystalline pigment, it is particularly preferable to disperse the charge generating material under conditions that do not change the crystal form. Further, at the time of dispersion, it is effective to make the particle size of the charge generating material 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

Moreover, as a solvent used for these dispersions, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran Ordinary organic solvents such as methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in admixture of two or more.
The thickness of the charge generation layer 13 is generally 0.1 to 5 μm, preferably 0.2 to 2.0 μm. In addition, as a coating method used when the charge generation layer 13 is provided, a usual method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like. Can be used.

Next, the charge transport layer 14 will be described.
A known charge transport material can be used for the charge transport layer 14. The charge transport layer 14 may be formed by containing a charge transport material and a binder resin, or may be formed by using a polymer charge transport material that also functions as a binder resin.
Charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds , Electron transport compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore-transporting compounds.
These charge transport materials can be used alone or in combination of two or more, but are not limited thereto. These charge transport materials can be used singly or in combination of two or more, but materials having a structure represented by the following formulas (A) to (C) are preferable from the viewpoint of mobility.

In the formula (A), R ¹⁴ represents a hydrogen atom or a methyl group. N means 1 or 2. Ar ⁶ and Ar ⁷ represent a substituted or unsubstituted aryl group, or —C (R ¹⁸ ) ═C (R ¹⁹ ) (R ²⁰ ), —CH═CH—CH═C (Ar) ₂ , As a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms. .
R ¹⁸ , R ¹⁹ and R ^{20 each} represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Ar represents a substituted or unsubstituted aryl group.

In the formula (B), R ¹⁵ and R ¹⁵ ′ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ¹⁶ , R ¹⁶ ′, R ¹⁷ and R ¹⁷ ′ may be the same or different, and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 2 carbon atoms. An amino group substituted with an alkyl group, a substituted or unsubstituted aryl group, or —C (R ¹⁸ ) ═C (R ¹⁹ ) (R ²⁰ ), —CH═CH—CH═C (Ar) ₂ Represent. m and n are integers of 0-2. R ¹⁸ , R ¹⁹ , R ²⁰ and Ar are the same as described in the formula (A).

In Formula (C), R ²¹ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, or —CH═CH—CH═C (Ar ) ₂ (Ar represents a substituted or unsubstituted aryl group). R ²² and R ²³ may be the same or different, and are an amino group substituted with a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms. Represents a group or a substituted or unsubstituted aryl group.

Further, examples of the binder resin used for the charge transport layer 14 include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, and styrene-butadiene copolymer. , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, Polymer charge transport materials such as poly-N-vinylcarbazole, polysilane, and polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 can also be used. .
These binder resins can be used alone or in admixture of two or more. The blending ratio (weight ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

  A polymer charge transport material can also be used alone. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane can be used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 have a high charge transporting property and are particularly preferable. The polymer charge transport material can be used alone to form the charge transport layer 14, but may be used by mixing with the binder resin.

The thickness of the charge transport layer 14 is generally 5 to 50 μm, preferably 10 to 30 μm.
As a coating method, a normal method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method can be used. Furthermore, as a solvent used when forming the charge transport layer 14, aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, methylene chloride, chloroform and ethylene chloride are used. Ordinary organic solvents such as halogenated aliphatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, or straight chain ethers may be used alone or in admixture of two or more.

In addition, additives such as antioxidants, light stabilizers, and heat stabilizers are added to the photosensitive layer for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, or light or heat generated in the image forming apparatus. Can be added.
For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine. In addition, at least one kind of electron accepting substance can be contained for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use.

Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, benzene derivatives having electron-withdrawing substituents such as fluorenone, quinone and Cl, CN, NO ₂ are particularly preferred.

-Latent image carrier surface-
Next, the structure of the surface part of the latent image carrier used in the present invention (the part corresponding to the protective layer 15 in the case of the laminated structure shown in FIG. 3), in particular, the resin material having a crosslinked structure contained on the surface. Will be described in more detail.
In the present invention, since the surface (outermost surface layer) of the latent image carrier contains a resin having a crosslinked structure, the surface has high hardness and excellent wear resistance. For this reason, even if image formation is performed for a longer period of time, scratches are generated on the surface or surface wear is suppressed, so that more uniform cleaning is possible.

As a material constituting the outermost surface layer, at least a resin having a crosslinked structure is used in order to improve wear resistance and ensure sufficient hardness. When such a material is not used, the surface hardness is low and sufficient wear resistance cannot be obtained, so that scratches and wear easily occur, and image formation can be performed for a longer period of time. become unable.
In addition to the resin having a cross-linked structure, the outermost surface layer may include a binder resin having no cross-linked structure, conductive fine particles, a charge transporting material (compound having charge transporting ability), and fluorine as necessary. Lubricating fine particles made of a resin, an acrylic resin, or the like may be included. When forming the outermost surface layer, a hard coat agent such as silicon or acrylic can be used as necessary. The details of the method for forming the outermost surface layer will be described later. For the formation of the outermost surface layer, a solution for forming the outermost surface layer containing at least a precursor constituting a resin having a crosslinked structure is used.

  In addition, as the resin having a crosslinked structure, various materials can be used from the viewpoint of ensuring the hardness of the outermost surface layer. From the viewpoint of characteristics, phenol resins, urethane resins, siloxane resins, epoxy resins, and the like can be given. Among these, phenol resins and siloxane resins are particularly preferable from the viewpoint of durability. The phenolic resin is more preferably a phenolic resin obtained by crosslinking a phenol derivative having a methylol group.

Furthermore, from the viewpoint of electrical characteristics, image quality maintenance, and the like, the resin having a crosslinked structure preferably has charge transportability (including a structural unit having charge transportability). In this case, in the laminated structure type latent image carrier as shown in FIG. 3, the protective layer 15 can also function as a part of the charge transport layer 14.
The structural unit having such a charge transporting capability is preferably a charge transporting material having at least one selected from a hydroxyl group, a carboxyl group, an alkoxysilyl group, an epoxy group, a thiol group, and an amino group.
Furthermore, it is preferable that the infrared absorption spectrum of the outermost surface layer containing this phenolic resin satisfies the condition represented by the following formula (3). This is because of excellent electrical characteristics and high image quality.
Formula (3) (P2 / P1) ≦ 0.2
However Shikichu, P1 is the absorbance of the maximum absorption peaks at 1560cm ^-1 ~1640cm ^-1, P2 represents the absorbance of the maximum absorption peaks at 1645cm ^-1 ~1700cm ^-1.

The reason why the above-mentioned effect can be obtained when the infrared absorption spectrum of the outermost surface layer containing the phenolic resin satisfies the above formula (3) is not necessarily clear, but the present inventors speculate as follows.
That is, in the process of forming a coating film using a phenol derivative having a methylol group, it is considered that a part of the methylol group of the phenol derivative becomes an oxide such as a formyl group. Such an oxide such as a formyl group is considered to act as a carrier trap that hinders charge transport in the photoconductor, thereby reducing the electrical characteristics of the photoconductor. Here, in the infrared absorption spectrum, the maximum absorption peaks at 1560cm ^-1 ~1640cm ^-1 (P1) corresponds to the aromatic C-C stretching vibration of a phenol derivative. The maximum absorption peaks at 1645cm ^-1 ~1700cm ^-1 (P2) is thought to be derived from the oxide such as a formyl group.

That is, it is considered that the outermost surface layer containing a phenolic resin having a small absorbance ratio (P2 / P1) has few oxides such as formyl groups in the phenolic resin and is excellent in carrier transportability. The phenolic resin is synthesized using the above-mentioned phenol derivative having a methylol group, and the absorbance ratio (P2 / P1) of the outermost surface layer containing this phenolic resin is 0.2 or less. It is considered that excellent image quality was achieved. Note that a photoreceptor provided with an outermost surface layer containing a phenolic resin has excellent electrical characteristics and mechanical strength, and this is also considered to be a factor that can achieve high image quality.
The absorbance ratio (P2 / P1) is preferably 0.18 or less, and more preferably 0.17 or less. When the absorbance ratio (P2 / P1) exceeds 0.2, the carrier transportability is lowered, the electrical characteristics of the photoreceptor are insufficient, and the image quality may be lowered.

Examples of the phenol derivative having a methylol group include monomers of monomethylolphenols, dimethylolphenols or trimethylolphenols, mixtures thereof, oligomers thereof, or mixtures of these monomers and oligomers.
Such phenol derivatives having a methylol group include resorcin, bisphenol, etc., substituted phenols containing one hydroxyl group such as phenol, cresol, xylenol, paraalkylphenol, paraphenylphenol, and two hydroxyl groups such as catechol, resorcinol, hydroquinone, etc. It is obtained by reacting a compound having a phenol structure, such as bisphenols such as substituted phenols, bisphenol A and bisphenol Z, biphenols, etc., with formaldehyde, paraformaldehyde, etc. in the presence of an acid catalyst or an alkali catalyst. Generally what is marketed as a phenol resin can also be used. In the present specification, a relatively large molecule having about 2 to 20 repeating molecular structural units is referred to as an oligomer, and a molecule smaller than that is referred to as a monomer.

As the acid catalyst, sulfuric acid, paratoluenesulfonic acid, phosphoric acid and the like are used. As the alkali catalyst, hydroxides or amine catalysts of alkali metals and alkaline earth metals such as NaOH, KOH, Ca (OH) ₂ and Ba (OH) ₂ are used.
Examples of the amine catalyst include, but are not limited to, ammonia, hexamethylenetetramine, trimethylamine, triethylamine, and triethanolamine. When a basic catalyst is used, the carrier is remarkably trapped by the remaining catalyst, and the electrophotographic characteristics tend to be deteriorated. Therefore, it is preferable to inactivate or remove by neutralizing with an acid or contacting with an adsorbent such as silica gel or an ion exchange resin.
Moreover, as a phenol derivative which has a methylol group, a phenol resin is preferable and a resol type phenol resin is more preferable.

As the charge transport material having at least one selected from a hydroxyl group, a carboxyl group, an alkoxysilyl group, an epoxy group, a thiol group and an amino group, the following general formula (I), (II), (III) or (IV) It is preferable that it is a compound shown by these.
The charge transport material having a plurality of epoxy groups is preferably a compound represented by the following general formula (IV).

· General formula (I) F - [(X 1) m 1 - (R 1) m 2 -Y] m 3
In the above formula (I), F represents an organic group derived from a compound having a hole transporting ability, X ¹ represents an oxygen atom or a sulfur atom, R ¹ represents an alkylene group (preferably having 1 to 15 carbon atoms, 1 10 is more preferable), Y represents a hydroxyl group, a carboxyl group (—COOH), a thiol group (—SH) or an amino group (—NH ₂ ), m ₁ and m ₂ each independently represents 0 or 1, m ₃ is an integer of 1-4.

- formula (II) F - [(X 2) n 1 - (R 2) n 2 - (Z) n 3 G] n 4
In the above formula (II), F represents an organic group derived from a compound having a hole transporting ability, X ² represents an oxygen atom or a sulfur atom, R ² represents an alkylene group (preferably having 1 to 15 carbon atoms, 1 10 is more preferable), Z represents an alkylene group, oxygen atom, sulfur atom, NH or COO, G represents an epoxy group, n ₁ , n ₂ and n ₃ each independently represents 0 or 1, n ₄ represents An integer of 1 to 4 is shown.

General formula (III) F- [D-Si (R ³ ) (3-a) Qa] b
In formula (III), F represents an organic group derived from a compound having a hole transporting ability, D represents a divalent group having flexibility, R ³ represents a hydrogen atom, a substituted or unsubstituted alkyl group ( The number of carbon atoms is preferably 1-15, more preferably 1-10, or a substituted or unsubstituted aryl group (carbon number is preferably 6-20, more preferably 6-15), and Q is a hydrolyzable group. A represents an integer of 1 to 3, and b represents an integer of 1 to 4.

In addition, as the divalent group D having flexibility, specifically, a site of F for imparting photoelectric characteristics, a substituted silicon group contributing to the construction of a three-dimensional inorganic glassy network, It is a divalent group that plays a role in linking.
In addition, D represents an organic group structure that imparts moderate flexibility to the portion of the inorganic glassy network that is hard but brittle, and plays a role of improving mechanical toughness as a film.
Specific examples _{D, -C α H 2α -,} - C β H 2β-2 -, - C γ H 2γ-4 - 2 divalent hydrocarbon group (here represented by, alpha is 1 to 15 Represents an integer, β represents an integer of 2 to 15, and γ represents an integer of 3 to 15), —COO—, —S—, —O—, —CH ₂ —C ₆ H ₄ —, —N═ CH—, — (C ₆ H ₄ ) — (C ₆ H ₄ ) —, and characteristic groups having a structure in which these characteristic groups are arbitrarily combined, and further, the constituent atoms of these characteristic groups are substituted with other substituents. And the like. The hydrolyzable group Q is preferably an alkoxy group, more preferably an alkoxy group having 1 to 15 carbon atoms.

· General formula (IV) F - [(X 2) n 1 - (R 2) n 2 - (Z) n 3 G] n 4
In the above formula (IV), F represents an organic group derived from a compound having a hole transporting ability, X ² represents an oxygen atom or a sulfur atom, R ² represents an alkylene group (1 to 15 carbon atoms are preferred, preferably 1 10 is more preferable), Z is an alkylene group, oxygen atom, sulfur atom, NH or COO, G is an epoxy group, n ₁ , n ₂ and n ₃ are each independently 0 or 1, n ₄ is An integer of 2 to 4 is shown.
As the organic group F derived from the compound having a hole transporting ability in the compounds represented by the general formulas (I) to (IV), a compound represented by the following general formula (VI) is preferable.

Here, in the above formula (VI), Ar ¹ , Ar ² , Ar ³ and Ar ⁴ each independently represent a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group or arylene group. ^{1 to} 4 of Ar ^{1 to} Ar ⁵ are-[(X ¹ ) m _1- (R ¹ ) m ₂ -Y] and-[in the compounds represented by the above formulas (I) to (IV). _{^{(X 2) n 1 - (}} R 2) n 2 - (Z) n 3 G], or - has a portion with a bond represented by ^{[D-Si (R 3)} (3-a) Qa]. K represents 0 or 1.

Further, conductive particles may be added to the outermost surface layer in order to lower the residual potential. Examples of the conductive particles include metals, metal oxides, and carbon black. Among these, metals or metal oxides are more preferable.
Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, or those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony and tantalum-doped tin oxide, and antimony-doped zirconium oxide. It is done. These can be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion. From the viewpoint of transparency of the outermost surface layer, the average particle size of the conductive particles is preferably 0.3 μm or less, and particularly preferably 0.1 μm or less.

In addition, a compound represented by the following general formula (VII-1) can also be added to the outermost surface layer in order to control various physical properties such as strength and film resistance of the outermost surface layer.
General formula (VII-1) Si (R ³⁰ ) (4-c) Qc
In the above formula (VII-1), R ³⁰ represents a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, Q represents a hydrolyzable group, and c represents an integer of 1 to 4.

Specific examples of the compound represented by the general formula (VII-1) include the following silane coupling agents. Examples of silane coupling agents include tetrafunctional silanes such as tetramethoxysilane and tetraethoxysilane (c = 4); methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, methyltrimethoxyethoxysilane, vinyltri Methoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxy Silane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl L) Triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- (heptafluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H , 1H, 2H, 2H-perfluorodecyltriethoxysilane, trifunctional alkoxysilane such as 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (c = 3); dimethyldimethoxysilane, diphenyldimethoxysilane, methyl And bifunctional alkoxysilanes such as phenyldimethoxysilane (c = 2); monofunctional alkoxysilanes such as trimethylmethoxysilane (c = 1), and the like. Trifunctional and tetrafunctional alkoxysilanes are preferable for improving the strength of the film, and monofunctional and bifunctional alkoxysilanes are preferable for improving the flexibility and film formability.

  In addition, a silicon-based hard coat agent produced mainly from these coupling agents can also be used. Commercially available hard coat agents include KP-85, X-40-9740, X-40-2239 (manufactured by Shin-Etsu Silicone), and AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning). Etc.) can be used.

In order to increase the strength of the outermost surface layer, it is also preferable to use a compound having two or more silicon atoms as shown in the following general formula (VII-2).
General formula (VII-2) B- (Si (R ³¹ ) (3-d) Q _d ) ₂
In the above formula (VII-2), B represents a divalent organic group, R ³¹ represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, Q represents a hydrolyzable group, and d represents 1 to 3. Indicates an integer.

  The outermost surface layer is represented by the following general formula (VII-3) for the purpose of extending the pot life of the solution used for forming the outermost surface layer, controlling the film characteristics, reducing the torque, and improving the uniformity of the coating film surface. It is also possible to contain a cyclic compound having a repeating structural unit or a derivative thereof.

In the above formula (VII-3), A ¹ and A ² each independently represent a monovalent organic group.
Commercially available cyclic siloxane can be mentioned as a cyclic compound which has a repeating structural unit shown by general formula (VII-3). Specifically, cyclic dimethylcyclosiloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, 1,3,5-trimethyl-1,3,5- Triphenylcyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclotetrasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7 , 9-pentaphenylcyclopentasiloxane and other cyclic methylphenylcyclosiloxanes, hexaphenylcyclotrisiloxane and other cyclic phenylcyclosiloxanes, and 3- (3,3,3-trifluoropropyl) methylcyclotrisiloxane and other fluorine Atom-containing cyclosiloxanes, methylhydrosiloxa Mixture, pentamethylcyclopentasiloxane, mention may be made of phenyl hydrosilyl group-containing cyclosiloxanes of hydrocyclosiloxane like, cyclic siloxanes and vinyl group-containing cyclosiloxanes such as penta vinyl pentamethylcyclopentasiloxane like. These cyclic siloxane compounds may be used alone or in combination of two or more.

Furthermore, various fine particles can be added in order to control the contamination resistance adhesion, lubricity, hardness and the like of the surface of the photoreceptor. They can be used alone or in combination of two or more.
Examples of the fine particles include silicon atom-containing fine particles. The silicon atom-containing fine particles are fine particles containing silicon as a constituent element, and specific examples include colloidal silica and silicone fine particles. The colloidal silica used as the silicon atom-containing fine particles preferably has an average particle diameter of 1 to 100 nm, more preferably 10 to 30 nm. What was chosen from what was disperse | distributed and generally marketed can be used.

The solid content of colloidal silica in the outermost surface layer is not particularly limited, but preferably 0.1 to 0.1 on the basis of the total solid content of the outermost surface layer in terms of film formability, electrical properties, and strength. It is used in the range of 50% by mass, more preferably in the range of 0.1-30% by mass.
The silicone fine particles used as the silicon atom-containing fine particles are spherical and preferably have an average particle diameter of 1 to 500 nm, more preferably 10 to 100 nm, and are selected from silicone resin particles, silicone rubber particles, and silicone surface-treated silica particles. A commercially available product can be used.

  Silicone fine particles are small particles that are chemically inert and excellent in dispersibility in resins, and because the content required to obtain sufficient properties is low, photosensitivity can be achieved without inhibiting the crosslinking reaction. The surface properties of the body can be improved. That is, it is possible to improve the lubricity and water repellency of the surface of the photoreceptor while being uniformly incorporated into a strong cross-linked structure, and maintain good wear resistance and contamination resistance adhesion over a long period of time. The content of the silicone fine particles in the outermost surface layer is preferably in the range of 0.1 to 30% by mass, more preferably in the range of 0.5 to 10% by mass, based on the total solid content of the outermost surface layer. .

Other fine particles include fluorine-based fine particles such as ethylene tetrafluoride, trifluoride ethylene, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, and the 8th Polymer Material Forum Lecture Proceedings p89. Fine particles made of a resin obtained by copolymerizing a fluororesin and a monomer having a hydroxyl group, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO—TiO ₂ , ZnO Examples thereof include semiconductive metal oxides such as —TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , In ₂ O ₃ , ZnO, and MgO. For the same purpose, an oil such as silicone oil can be added.

  Examples of the silicone oil include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, methacryl-modified polysiloxane, and mercapto. Examples include reactive silicone oils such as modified polysiloxanes and phenol-modified polysiloxanes. These may be added in advance to the coating solution for forming the outermost surface layer, or may be impregnated under reduced pressure or increased pressure after producing the photoreceptor.

In addition, additives such as plasticizers, surface modifiers, antioxidants, and photodegradation inhibitors can also be used.
Examples of the plasticizer include biphenyl, biphenyl chloride, terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenyl phosphate, methyl naphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene, and various fluorohydrocarbons. An antioxidant having a hindered phenol, hindered amine, thioether or phosphite partial structure can be added to the outermost surface layer, which is effective in improving the potential stability and image quality when the environment changes.

  Examples of the antioxidant include the following compounds. For example, hindered phenols include “Sumilizer BHT-R”, “Sumilizer MDP-S”, “Sumilizer BBM-S”, “Sumizer WX-R”, “Sumizer NW”, “Sumizer BP-76”, “ Sumilizer BP-101 "," Sumilizer GA-80 "," Sumilizer GM "," Sumilizer GS "or more manufactured by Sumitomo Chemical Co., Ltd.," IRGANOX1010 "," IRGANOX1035 "," IRGANOX1076 "," IRGANOX1098 "," IRGANOX1098 "," 114 " ”,“ IRGANOX1222 ”,“ IRGANOX1330 ”,“ IRGANOX1425WL ”,“ IRGANOX1 20L "," IRGANOX 245 "," IRGANOX 259 "," IRGANOX 3114 "," IRGANOX 3790 "," IRGANOX 5057 "," IRGANOX 565 "or more, manufactured by Ciba Specialty Chemicals," ADK STAB AO-20 "," ADK STAB AO-30 "," ADEKA STAB " "AO-40", "ADK STAB AO-50", "ADK STAB AO-60", "ADK STAB AO-70", "ADK STAB AO-80", "ADK STAB AO-330" or more manufactured by Asahi Denka. Examples of hindered amines include “Sanol LS2626”, “Sanol LS765”, “Sanol LS770”, “Sanol LS744”, “Tinuvin 144”, “Tinuvin 622LD”, “Mark LA57”, “Mark LA67”, “Mark LA62”. ”,“ Mark LA68 ”,“ Mark LA63 ”,“ Smilizer TPS ”,“ Smilizer TP-D ”for thioethers,“ Mark 2112 ”,“ Mark PEP 8 ”,“ Mark PEP ”for phosphites -24G "," Mark PEP.36 "," Mark 329K "," Mark HP.10 ", and hindered phenols and hindered amine antioxidants are particularly preferable. Furthermore, these may be modified with a substituent such as an alkoxysilyl group capable of undergoing a crosslinking reaction with the material forming the crosslinked film.

In addition, the outermost surface layer includes polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin An insulating resin such as a resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, or polyvinyl pyrrolidone resin may be contained. In this case, the insulating resin can be added at a desired ratio, thereby allowing the coating film to adhere to an intermediate layer such as a charge transport layer provided on the substrate side of the outermost surface layer, heat shrinkage or repellency. Defects and the like can be suppressed.
The outermost surface layer is formed by applying and curing an outermost surface layer forming coating solution containing the above-described constituent materials on the intermediate layer.

  When the outermost surface layer is formed using the above-described charge transport material, it is preferable to add a catalyst to the protective layer forming coating solution, or to use the catalyst when preparing the protective layer forming coating solution. Catalysts used include inorganic acids such as hydrochloric acid, acetic acid, phosphoric acid and sulfuric acid, organic acids such as formic acid, propionic acid, oxalic acid, paratoluenesulfonic acid, benzoic acid, phthalic acid and maleic acid, potassium hydroxide, water An alkali catalyst such as sodium oxide, calcium hydroxide, ammonia, triethylamine, or a solid catalyst insoluble in the system can also be used.

In addition, in order to remove the catalyst at the time of synthesis from a phenol derivative having a methylol group, the phenol derivative is dissolved in an appropriate solvent such as methanol, ethanol, toluene, ethyl acetate, washed with water, reprecipitation using a poor solvent, etc. It is preferable to perform the above treatment or to perform treatment using an ion exchange resin or an inorganic solid.
For example, as the ion exchange resin, Amberlite 15, Amberlite 200C, Amberlist 15E (above, manufactured by Rohm and Haas); Dowex MWC-1-H, Dowex 88, Dowex HCR-W2 (above Rebachit SPC-108, Rebachit SPC-118 (above, Bayer); Diaion RCP-150H (Mitsubishi Kasei); Sumikaion KC-470, Duolite C26-C, Duolite C-433, Duolite-464 (above, manufactured by Sumitomo Chemical Co., Ltd.); Cation exchange resin such as Nafion-H (made by DuPont); Amberlite IRA-400, Amberlite IRA-45 (above, Rohm and Anion exchange resins such as (made by Haas) are listed.

Further, as the inorganic solid, an inorganic solid in which a group containing a protonic acid group such as Zr (O ₃ PCH ₂ CH ₂ SO ₃ H) ₂ or Th (O ₃ PCH ₂ CH ₂ COOH) ₂ is bonded to the surface. A polyorganosiloxane containing a protonic acid group such as a polyorganosiloxane having a sulfonic acid group; a heteropolyacid such as cobalt tungstic acid or phosphomolybdic acid; an isopolyacid such as niobic acid, tantalic acid or molybdic acid; silica gel, alumina, Single metal oxides such as chromia, zirconia, CaO, MgO; complex metal oxides such as silica-alumina, silica-magnesia, silica-zirconia, zeolites; clay minerals such as acid clay, activated clay, montmorillonite, and kaolinite Metal sulfates such as LiSO ₄ and MgSO ₄ ; gold such as zirconia phosphate and lanthanum phosphate Metal nitrate; LiNO ₃ , metal nitrate such as Mn (NO ₃ ) ₂ ; Group containing amino group such as solid obtained by reacting aminopropyltriethoxysilane on silica gel is bonded to the surface Inorganic solids: Polyorganosiloxanes containing amino groups such as amino-modified silicone resins.

For the coating solution for forming the outermost surface layer, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran; ethers such as diethyl ether and dioxane, etc. A solvent can be used. In order to apply a dip coating method generally used for the production of a photoreceptor, an alcohol solvent, a ketone solvent, or a mixed solvent thereof is preferable. In addition, the boiling point of the solvent used is preferably 50 to 150 ° C., and these can be arbitrarily mixed and used.
In addition, since an alcohol solvent, a ketone solvent, or a mixed solvent thereof is preferable as the solvent, the charge transport material used for forming the outermost surface layer to be used is soluble in these solvents. Is preferred.
Further, the amount of the solvent can be arbitrarily set, but if the amount is too small, the constituent material is likely to be precipitated. It is preferable to set it as a mass part, More preferably, it is 1-20 mass parts.

  Coating methods for forming the outermost surface layer using the outermost surface layer forming coating solution include blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain A usual method such as a coating method can be used. However, when a required film thickness cannot be obtained by a single application, the necessary film thickness can be obtained by applying a plurality of times. In addition, when performing the multiple application | coating several times, a heat processing may be performed every time of application | coating, and may be after carrying out multiple application | coating several times.

  After applying the outermost surface layer forming coating solution on an intermediate layer such as a charge transport layer, a curing treatment is performed. Usually, during the curing treatment, the curing temperature is high and the curing time is preferably long in order to promote the crosslinking reaction of the phenol derivative and increase the mechanical strength of the outermost surface layer. However, in such a case, the absorbance ratio (P2 / P1) tends to exceed 0.2, and the electrical characteristics are significantly deteriorated. Therefore, it is preferable to control with the curing temperature, the curing time, the crosslinking atmosphere or the curing catalyst so that the IR spectrum of the outermost surface layer satisfies the above conditions.

  That is, in order for the IR spectrum of the outermost surface layer to satisfy the condition represented by the above formula (3), the curing temperature during the curing treatment is preferably 100 to 190 ° C, more preferably 120 to 170 ° C. 160 ° C. is more preferable. The curing time is preferably 30 minutes to 2 hours, more preferably 30 minutes to 1 hour.

Further, as an atmosphere for performing the curing treatment (crosslinking reaction), the absorbance ratio (P2 / P1) is reduced under a so-called oxidation inert gas atmosphere (inert gas atmosphere) such as nitrogen, helium, and argon. It is effective. When the crosslinking reaction is performed in an inert gas atmosphere, the curing temperature can be set higher than in an air atmosphere (oxygen-containing atmosphere), and the curing temperature is 100 to 160 ° C. (preferably 110 to 150 ° C.). Is possible. The curing time can be 30 minutes to 2 hours (preferably 30 minutes to 1 hour). Further, in the compound represented by the general formula (I), the electric characteristics depending on the curing temperature are most when the site represented by (— (X ¹ ) m ₁ — (R ¹ ) m ₂ —Y) is —CH ₂ —OH. Therefore, the curing treatment is preferably performed in the above preferred temperature range.

  Furthermore, it is preferable to use a curing catalyst during the curing treatment. Examples of the curing catalyst include bissulfonyldiazomethanes such as bis (isopropylsulfonyl) diazomethane, bissulfonylmethanes such as methylsulfonyl p-toluenesulfonylmethane, and sulfonylcarbonyldiazomethanes such as cyclohexylsulfonylcyclohexylcarbonyldiazomethane, 2 Sulfonylcarbonyl alkanes such as methyl-2- (4-methylphenylsulfonyl) propiophenone, nitrobenzyl sulfonates such as 2-nitrobenzyl p-toluenesulfonate, alkyl and aryl sulfonates such as pyrogallol trismethanesulfonate (G) benzoin sulfonates such as benzoin tosylate, N- (trifluoromethylsulfonyloxy) phthalimide N-sulfonyloxyimides, pyridones such as (4-fluorobenzenesulfonyloxy) -3,4,6-trimethyl-2-pyridone, 2,2,2-trifluoro-1-trifluoromethyl-1 Photoacid generators such as sulfonate esters such as-(3-vinylphenyl) -ethyl-4-chlorobenzenesulfonate, onium salts such as triphenylsulfonium methanesulfonate and diphenyliodonium trifluoromethanesulfonate, protonic acid or Lewis Examples thereof include compounds obtained by neutralizing acids with Lewis bases, mixtures of Lewis acids and trialkyl phosphates, sulfonic acid esters, phosphate esters, onium compounds, and carboxylic anhydride compounds.

Compounds obtained by neutralizing a protonic acid or Lewis acid with a Lewis base include halogenocarboxylic acids, sulfonic acids, sulfuric acid monoesters, phosphoric acid mono- and diesters, polyphosphoric acid esters, boric acid mono- and diesters, and the like. Various amines such as monoethylamine, triethylamine, pyridine, piperidine, aniline, morpholine, cyclohexylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, or trialkylphosphine, triarylphosphine, trialkylphosphite, triaryl Compounds neutralized with phosphite, as well as NureCure 2500X, 4167, X-47-110, 3525, 5225 commercially available as acid-base blocking catalysts (trade name, King Ndasutori Co., Ltd.), and the like. Examples of the compound obtained by neutralizing a Lewis acid with a Lewis base include compounds obtained by neutralizing a Lewis acid such as BF ₃ , FeCl ₃ , SnCl ₄ , AlCl ₃ , ZnCl ₂ with the above Lewis base.

Examples of the onium compound include triphenylsulfonium methanesulfonate, diphenyliodonium trifluoromethanesulfonate, and the like.
Examples of the carboxylic anhydride compound include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, lauric anhydride, oleic anhydride, stearic anhydride, n-caproic anhydride, n-caprylic anhydride, and n-capric anhydride. , Palmitic anhydride, myristic anhydride, trichloroacetic anhydride, dichloroacetic anhydride, monochloroacetic anhydride, trifluoroacetic anhydride, heptafluorobutyric anhydride, and the like.

Specific examples of Lewis acids include, for example, boron trifluoride, aluminum trichloride, titanium chloride, ferric chloride, ferrous chloride, ferric chloride, zinc chloride, zinc bromide, stannous chloride. , Metal halides such as stannic chloride, stannous bromide, stannic bromide, organometallic compounds such as trialkylboron, trialkylaluminum, dialkylaluminum halide, monoalkylaluminum halide, tetraalkyltin , Diisopropoxyethyl acetoacetate aluminum, tris (ethyl acetoacetate) aluminum, tris (acetylacetonato) aluminum, diisopropoxy bis (ethyl acetoacetate) titanium, diisopropoxy bis (acetylacetonato) titanium, tetrakis (N-propylacetoacetate Zirconium, Tetrakis (acetylacetonato) zirconium, Tetrakis (ethylacetoacetate) zirconium, Dibutyl-bis (acetylacetonato) tin, Tris (acetylacetonato) iron, Tris (acetylacetonato) rhodium, Bis (acetyl) Acetonato) zinc, tris (acetylacetonato) cobalt metal chelate compounds, dibutyltin dilaurate, dioctyltin ester malate, magnesium naphthenate, calcium naphthenate, manganese naphthenate, iron naphthenate, cobalt naphthenate, copper naphthenate , Zinc naphthenate, zirconium naphthenate, lead naphthenate, calcium octylate, manganese octylate, iron octylate, cobalt octylate, zinc octylate, zirconium octylate, Tin chill acid, lead octylate, zinc laurate, magnesium stearate, aluminum stearate, calcium stearate, cobalt stearate, zinc stearate, and metal soaps such as stearate lead. These may be used individually by 1 type and may be used in combination of 2 or more type.
Although the usage-amount in particular of these curing catalysts is not restrict | limited, 0.1-20 mass parts is preferable with respect to a total of 100 mass parts of solid content contained in the coating liquid for outermost surface layer formation, and 0.3-10 mass parts is Particularly preferred.

When an organometallic compound is used as a catalyst when forming the outermost surface layer, it is preferable to add a polydentate ligand from the viewpoint of pot life and curing efficiency. Examples of such multidentate ligands include, but are not limited to, those shown below and those derived therefrom.
Specifically, β-diketones such as acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, and dipivaloylmethylacetone; acetoacetates such as methyl acetoacetate and ethyl acetoacetate; bipyridine and derivatives thereof; glycine and its Derivatives; ethylenediamine and derivatives thereof; 8-oxyquinoline and derivatives thereof; salicylaldehyde and derivatives thereof; catechol and derivatives thereof; bidentate ligands such as 2-oxyazo compounds; diethyltriamine and derivatives thereof; nitrilotriacetic acid and derivatives thereof And tridentate ligands such as ethylenediaminetetraacetic acid (EDTA) and derivatives thereof. In addition to the organic ligands as described above, inorganic ligands such as pyrophosphoric acid and triphosphoric acid can be exemplified.
As the multidentate ligand, a bidentate ligand is particularly preferable, and specific examples include a bidentate ligand represented by the following general formula (VII-4) in addition to the above.

In the formula (VII-4), R ³² and R ³³ each independently represent an alkyl group having 1 to 10 carbon atoms, a fluorinated alkyl group, or an alkoxy group having 1 to 10 carbon atoms.
Among the above, as the multidentate ligand, a bidentate ligand represented by the following general formula (VII-4) is more preferable, and R ³² and R ^{33 in the following} general formula (VII-4) are the same. Are particularly preferred. By making R ³² and R ^{33 the} same, the coordination power of the ligand near room temperature becomes strong, and the coating solution for forming the outermost surface layer can be further stabilized.
The compounding amount of the polydentate ligand can be arbitrarily set, but is preferably 0.01 mol or more, more preferably 0.1 mol or more, and still more preferably with respect to 1 mol of the organometallic compound used. 1 mole or more.

When the outermost surface layer is formed so that the absorbance ratio (P2 / P1) of the infrared absorption spectrum satisfies the above conditions, it is necessary to set the curing temperature relatively low in an air atmosphere. . Therefore, it is difficult to lower the oxygen transmission coefficient at 25 ° C. of the outermost surface layer, but the absorbance ratio (P2 / P1) is made to satisfy the above condition, and the oxygen transmission coefficient at 25 ° C. of the outermost surface layer is By satisfying the condition, a photoreceptor that can further improve electrical characteristics and achieve higher image quality can be obtained.
The thickness of the outermost surface layer is preferably 0.5 to 15 μm, more preferably 1 to 10 μm, and more preferably 1 to 5 μm.

-Toner (and developer)-
The developer used in the present invention may be either a one-component developer composed of toner or a two-component developer composed of toner and carrier.
The toner used in the present invention is not particularly limited by the production method. For example, kneading is performed by kneading, pulverizing, and classifying a binder resin, a colorant, a release agent, and a charge control agent as necessary. A method of changing the shape of particles obtained by a pulverization method or a kneading pulverization method by mechanical impact force or thermal energy, a dispersion formed by emulsion polymerization of a polymerizable monomer of a binder resin, and coloring Emulsification that agglomerates toner components and heat-fuses them in a mixed liquid in which an agent dispersion, a release agent dispersion, and, if necessary, a dispersion containing a charge control agent are mixed to obtain toner particles Suspension weight for polymerization by suspending a solution containing a polymerization monomer, a polymerizable monomer for obtaining a binder resin, a colorant, a release agent, and, if necessary, a charge control agent in an aqueous solvent. Legal, binder resin, colorant, release agent, and if necessary, charge control agent Those obtained by a solution suspension method or the like free solution is suspended in an aqueous solvent and granulated can be used.

  In addition, a known method such as a production method in which the toner obtained by the above method is used as a core, and binder resin fine particles are further adhered and then heat-fused to have a core-shell structure can be used. Among these production methods, from the viewpoint of shape control and particle size distribution control, suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method in which an aqueous solvent is used are preferable, and emulsion polymerization aggregation method is particularly preferable.

  The toner contains a binder resin, a colorant, a release agent, and the like, and may contain silica or a charge control agent if necessary. The volume average particle size of the toner is preferably in the range of 2 to 12 μm, and more preferably in the range of 3 to 9 μm. Further, as described above, by using a toner having a shape factor SF in the range of 100 to 140, an image with high development, transferability, and high image quality can be obtained. In particular, in the present invention using a magnetic brush as the cleaning means, it is preferable that the toner has a high degree of sphericity in order to maintain high transferability. In addition, the range of a more preferable shape index is 100-135, More preferably, it is the range of 100-120.

The toner shape factor SF means a value defined by the following equation (4).
Formula (4) SF = 100 × π × ML ² / 4A
In Equation (4), SF represents the toner shape factor, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
Here, the absolute maximum length of the toner diameter and the projected area of the toner represented by the formula (4) are obtained by photographing a toner particle image magnified by 500 times using an optical microscope (Nikon, Microphoto-FXA). The obtained image information was obtained by introducing the image information into an image analysis apparatus (Luzex III) manufactured by Nicole, Inc. via an interface and performing image analysis. The value of the shape factor SF was calculated as an average value based on data obtained by measuring 1000 toner particles sampled randomly.

  Further, the volume average particle diameter (cumulative volume average particle diameter volume average particle diameter) of the toner is measured by a measuring instrument such as Coulter Counter TAII (manufactured by Beckman-Coulter) or Multisizer II (manufactured by Beckman-Coulter). For the particle size range (channel) divided on the basis of the particle size distribution, the volume was determined as the particle size at 50% cumulative by drawing the cumulative distribution from the small diameter side.

  As the binder resin for the toner, styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; acrylic Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; and homopolymers and copolymers of Can.

  Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include a polymer, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  In addition, a charge control agent may be added to the toner as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

Further, as described above, spherical fine powder is always externally added to the toner used in the present invention.
When the spherical fine powder is an organic fine powder, for example, acrylic resin particles, styrene resin particles, styrene acrylic resin particles, polyester resin particles, urethane resin particles, and the like can be used. Further, when the spherical fine powder is an inorganic fine powder, it is preferable to use silica particles. As the spherical fine powder, it is more preferable to use an organic fine powder rather than an inorganic fine powder from the viewpoint that the occurrence of scratches and wear on the surface of the photoreceptor can be surely prevented.

The average particle size of the spherical fine powder needs to be in the range of 70 to 200 nm as described above, preferably in the range of 80 to 160 nm, and preferably in the range of 100 to 150 nm. More preferred.
When the average particle diameter of the spherical fine powder is less than 70 nm or exceeds 200 nm, the fluidity of the toner is not improved, so that the discharge product removal capability is insufficient, and image blurring and white spots occur.

  The average particle size of the spherical fine powder was obtained by photographing a particle image magnified 10,000 times using a scanning electron microscope (FE-SEM, photographing condition: acceleration voltage 5 KV), and analyzing the obtained image information. It was obtained by introducing it into the apparatus and performing image analysis. Moreover, the value of the average particle diameter was calculated as the number average particle diameter based on data obtained by measuring 100 randomly sampled particles.

Further, the spherical fine powder needs to have a true spherical shape or a shape close to a true sphere. When the sphericity is low (that is, when the shape is indefinite), the fluidity of the toner is not improved, so the discharge product removal capability is insufficient, and image blurring and white spots occur.
The sphericity of the spherical fine powder is preferably such that the shape factor SF ′ of the spherical fine powder is in the range of 100 to 120, more preferably in the range of 100 to 110.
Here, the spherical differential shape factor SF ′ means a value defined by the following equation (5).
Formula (5) SF ′ = 100 × π × ML ² / 4A
In Equation (5), SF ′ represents the spherical derivative shape factor, ML represents the absolute maximum length of the spherical derivative, and A represents the area of the spherical derivative. Here, the area of the spherical differential is taken with a scanning electron microscope (FE-SEM, imaging conditions: acceleration voltage 5 KV), and a particle image enlarged at a magnification of 10000 times is taken, and the obtained image information is introduced into an image analyzer. And obtained by performing image analysis. The value of the shape factor SF ′ was calculated as an average value based on data obtained by measuring 100 randomly sampled particles.

The addition amount of spherical fine powder to the toner is preferably 0.1% by weight or more, and more preferably 0.5% by weight or more. If the addition amount is less than 0.1% by weight, the effect of weakening the adhesion between the surface of the photoreceptor and the discharge product becomes insufficient, and the discharge product cannot be sufficiently removed, resulting in image blurring and white spots. There is a case.
In addition, although the one where addition amount is large is preferable, it is preferable to set it as 2.0 weight% or less practically.

Furthermore, in the present invention, known external additives can be added as needed in addition to the spherical fine powder, but it is particularly preferable to use an abrasive. By using an abrasive, the surface of the photoreceptor is more polished and the discharge products are more easily removed.
As the abrasive, irregularly shaped inorganic fine particles having particularly excellent polishing properties are particularly preferable. Examples of such inorganic fine particles include cerium oxide, alumina, silica, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, antimony oxide, tungsten oxide, tin oxide, Various inorganic oxides such as tellurium oxide, manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, boron nitride, nitrides, borides and the like are preferably used.

Further, titanium coupling agents such as tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, γ- (2-amino) Ethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane Hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxy The treatment may be performed with a silane coupling agent such as silane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane.
Further, hydrophobic treatment with a higher fatty acid metal salt such as silicone oil, aluminum stearate, zinc stearate, calcium stearate can be preferably performed.

  As a particle size of an abrasive | polishing agent, 50 nm-10 micrometers are preferable, More preferably, they are 100 nm-1 micrometer. If the particle size of the abrasive is too small, the polishing effect is insufficient, and if it is too large, scratches may occur, which is not preferable. The appropriate amount of abrasive added to the toner is desirably 0.1% by weight or more. A more preferable range is 0.2% by weight or more. If it is less than 0.1% by weight, a sufficient polishing effect may not be obtained. In addition, from the viewpoint of ensuring a sufficient polishing effect, it is preferable that the amount of the abrasive added is large, but in practice it is preferably 1.0% by weight or less.

  Other inorganic oxides added to the toner include small-diameter inorganic oxides with a primary particle size of 50 nm or less for powder flowability, charge control, etc. Mention may be made of large-diameter inorganic oxides. As these inorganic oxide fine particles, known ones can be used, but in order to perform precise charge control, it is preferable to use silica and titanium oxide in combination. Further, the surface treatment of the small-diameter inorganic fine particles increases the dispersibility and increases the effect of improving the powder fluidity.

  A lubricant can also be added to the toner used in the present invention. Examples of the lubricant include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, and fatty acid metal salts; low molecular weight polyolefins such as polypropylene, polyethylene, and polybutene; silicones having a softening point by heating; oleic acid amide, Aliphatic amides such as erucic acid amide, ricinoleic acid amide, stearic acid amide, etc .; plant waxes such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal systems such as beeswax Wax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and petroleum wax; and their modified products can be used alone or in combination. Also good

  In particular, the lubricant added to the toner is preferably a fatty acid metal salt, particularly zinc stearate, which has a high friction reducing effect due to its cleavage property. The amount of zinc stearate added to the toner is preferably 0.01 to 2.0% by weight, more preferably 0.05 to 0.5% by weight. When the amount added is less than 0.01% by weight, sufficient lubrication effect cannot be exhibited. When the amount added is more than 2.0% by weight, the image carrier adheres excessively and image flow occurs under high temperature and high humidity. In addition, the charging property of the toner itself is adversely affected.

  Further, the above various external additives can be externally added to the toner by mixing with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

There is no restriction | limiting in particular as a carrier which can be used for a two-component developer, A well-known carrier can be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a coating resin layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.
The mixing ratio (weight ratio) of the toner and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and more preferably in the range of 3: 100 to 20: 100. preferable.

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

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

Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable.
The volume average particle diameter of the carrier core material is generally 10 to 500 μm, preferably 20 to 100 μm. Furthermore, for the purpose of low stress, a spherical core material produced by a polymerization method can be used. The core has a true specific gravity of preferably 3.0 to 5.0 g / cm ³ and a saturation magnetization of 40 emu / g or more.

When a polymer of (meth) acrylic acid alkyl ester is used as the coating resin for coating the carrier core material, two or more types of monomers having different alkyl groups can be used.
Examples of these monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and tertiary butyl (meth) acrylate. , Isobutyl (meth) acrylate, tertiary pentyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate, isohexyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Can be mentioned.

  Examples of a monomer having a carboxylic acid group to be copolymerized with a (meth) acrylic acid alkyl ester include (meth) acrylic acid, styrene such as carboxyl styrene having a carboxyl group, p-carboxy styrene Examples include those containing two or more carboxyl groups. The same effect can be seen with a polymer having a carboxyl group by allowing a metal cation to act on an acrylic copolymer, such as an ionomer resin.

  The amount of carboxylic acid varies depending on the type of carboxylic acid monomer, the amount of carboxylic acid group, and the molecular weight of the monomer, but is 0.1 to 15.0 weight based on the total monomer used in the synthesis of the coating resin. % Is suitable, and more preferably 0.5 to 10.0% by weight can exhibit a function with respect to adhesion and environmental stability. If the amount introduced is small, the effect of durability is small, and if it is too large, the viscosity is high, it is difficult to obtain a uniform coating layer, and the environmental difference is worsened.

When a fluorine-containing monomer is used in the synthesis of the coating resin, a perfluoroacrylic monomer is preferable. Examples include tetrafluoropropyl methacrylate, pentafluoropropyl methacrylate, octafluoropentyl methacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, and other fluorine-containing acrylic monomers, as well as trifluoroethylene, tetrafluoroethylene, Fluorine-containing monomers such as hexafluoropropene and perfluoroalkyl vinyl ether can also be used.
The amount of fluorine in the coating resin can be selected according to the purpose. When the amount of fluorine is large, the contamination is improved, but the charge tends to decrease or the adhesion to the core material tends to deteriorate.
Although depending on the monomer species, the amount of the fluorine monomer based on the total monomer used for the synthesis of the coating resin is suitably 0.1 to 60.0% by weight, more preferably 0.5 to 50. 0% by weight can exhibit functions with respect to adhesion and charge level.

  The copolymerization ratio of the coating resin can be appropriately selected depending on the toner type and the system suitability. In particular, two or more kinds of (meth) acrylic acid alkyl esters can obtain desired characteristics by changing the polymerization ratio. As a copolymerization method of these monomers, a polymerization method such as random copolymerization or graft copolymerization can be used. Graft copolymerization is an excellent polymerization method in that the function can be easily expressed, the adhesion to the core can be increased, and the glass transition temperature of the coating resin can be increased.

As a typical method for forming the coating resin layer on the surfaces of the carrier core material and the charging member, a raw material solution for forming the coating resin layer (a matrix resin, resin fine particles, conductive fine powder, etc. are appropriately included in the solvent) Is to be used.
Specifically, for example, a dipping method in which the powder of the carrier core material and the charge imparting member are immersed in the coating resin layer forming solution, and a spray method in which the coating resin layer forming solution is sprayed on the surfaces of the carrier core material and the charge imparting member In addition, the carrier core material and the coating resin layer forming solution are mixed in a kneader coater in a fluidized bed method in which the carrier core material is floated by flowing air and the coating resin layer forming solution is sprayed, and then the solvent is removed. Examples include a kneader coater method, but the method is not particularly limited to those using a solution, and depending on the carrier core material and the charge imparting member to be applied, an appropriate method such as a powder coating method in which the resin powder is heated and mixed is used. I can do it.

The coating amount of the coating resin is suitably in the range of 0.05 to 5.0% by weight with respect to the core material in order to achieve both image quality, secondary obstruction and chargeability. Further, when applying to the charge imparting member, it is preferable to appropriately adjust the coating amount and the coating method so that an appropriate film thickness can be obtained with respect to the charge amount, maintainability and the like.
The solvent used in the raw material solution for forming the coating resin layer is not particularly limited as long as it dissolves the matrix resin constituting the coating resin layer. For example, aromatic hydrocarbons such as xylene and toluene, Ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and halogen compounds such as chloroform and carbon tetrachloride can be used.

  Specific resin coating methods for the core material include an immersion method in which the carrier core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, and a carrier core material And a kneader coater method in which the core material of the carrier and the coating layer forming solution are mixed in a kneader coater, and the solvent is removed in a kneader coater.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following description, “parts” means “parts by weight” unless otherwise specified.

<Production of photoconductor>
-Production of photoreceptor 1-
(Preparation of latent image carrier 1)
A cylindrical Al substrate was polished by a centerless polishing apparatus, and the surface roughness was adjusted to Rz of 0.6 μm. Next, the outer peripheral surface of the Al substrate is degreased with an organic solvent, subsequently etched with a 2 wt% sodium hydroxide solution for 1 minute, neutralized with the alkali component remaining on the Al substrate surface, and further purified water Washing was performed.

Next, the outer peripheral surface of the Al base was anodized using a 10 wt% sulfuric acid solution to form an anodized film (current density 1.0 A / dm ² ). Subsequently, after rinsing with water, the Al substrate was immersed in a 1 wt% nickel acetate solution maintained at 80 ° C. for 20 minutes to perform sealing treatment, followed by pure water washing and drying treatment. In this way, an anodic oxide film (undercoat layer) having a thickness of 7 μm was formed on the outer peripheral surface of the Al base.

  Next, 1 of chlorogallium phthalocyanine having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) in the X-ray diffraction spectrum of 7.4 °, 16.6 °, 25.5 °, and 28.3 °. Part by weight, 1 part by weight of polyvinyl butyral (ESREC BM-S, Sekisui Chemical) and 100 parts by weight of n-butyl acetate were mixed and treated with a glass shaker for 1 hour to disperse the coating solution obtained. Was dip coated on the undercoat layer and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.15 μm.

  Subsequently, 2 parts by weight of a benzidine compound having a structure shown on the left side and 2 parts by weight of a polymer compound (viscosity average molecular weight = 39,000) shown on the right side are dissolved in 20 parts by weight of chlorobenzene. The solution is applied onto the charge generation layer by a dip coating method, followed by heat treatment at 110 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm, thereby obtaining a latent image carrier 1 (photosensitive member 1). It was.

-Production of photoreceptor 2-
The constituent materials shown below were dissolved in 5 parts of isopropyl alcohol, 3 parts of tetrahydrofuran and 0.3 part of distilled water, 0.5 parts of ion exchange resin (Amberlyst 15E) was added, and the mixture was stirred at room temperature for 24 hours. Decomposition was performed.
-Constituent material-
Compound 1 (compound shown below): 2 parts Methyltrimethoxysilane: 2 parts Tetramethoxysilane: 0.5 parts Colloidal silica: 0.3 parts Fluorine graft polymer (ZX007C: manufactured by Fuji Kasei): 0 .5 parts

  0.1 parts of aluminum trisacetylacetonate (Al (aqaq) 3) and 3,5-di-t-butyl-4-hydroxytoluene (BHT) are obtained by filtering and separating the ion exchange resin from the hydrolyzed product. ) 0.4 part is added, and this coating solution is applied to the surface of the photoreceptor 1 (charge transport layer surface) by a ring-type dip coating method, air-dried at room temperature for 30 minutes, and then cured by heat treatment at 170 ° C. for 1 hour. Then, a surface layer having a thickness of about 3 μm was formed to obtain a photoreceptor 2.

-Production of photoreceptor 3-
5 parts of the following compound 2, 7 parts of resol type phenol resin (PL-4852, manufactured by Gunei Chemical Co., Ltd.), 0.03 part of methylphenylpolysiloxane, and 20 parts of isopropanol are mixed and dissolved. A coating solution for forming a protective layer was obtained.
This coating solution was applied onto the charge transport layer of the photoreceptor 1 by a dip coating method and dried at 130 ° C. for 40 minutes to form a protective layer having a thickness of 3 μm. Thus, the photoreceptor 3 was obtained.
In addition, the drying process of any photoconductor including the photoconductor 3 was performed in an air atmosphere.
Further, a part of the protective layer of the obtained photoreceptor 3 was peeled off, and an infrared absorption (IR) spectrum was measured with an infrared spectrophotometer FT-730 (manufactured by Horiba, Ltd.), and an absorbance ratio (P2 / P1). ) Was calculated and P2 / P1 was 0.16.

-Preparation of toner and developer-
In the production of the toner and developer described below, the volume average particle diameter and the shape factor SF of the toner were obtained using the measurement apparatus and measurement method described above.

[Manufacture of toner base particles]
(Adjustment of resin fine particle dispersion)
A mixture of 370 g of styrene, 30 g of n-butyl acrylate, 8 g of acrylic acid, 24 g of dodecanethiol and 4 g of carbon tetrabromide was dissolved in 6 g of a nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anion Ion exchange in which 10 g of a surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is emulsion-polymerized in a flask in which 550 g of ion-exchanged water is dissolved, and 4 g of ammonium persulfate is dissolved in the flask while slowly mixing for 10 minutes. 50 g of water was added.
Subsequently, after carrying out nitrogen substitution in the flask, the contents in the flask were heated with an oil bath until the content reached 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion in which resin particles having an average particle size of 150 nm, a glass transition temperature Tg = 58 ° C., and a weight average molecular weight Mw = 11500 was obtained. The solid content concentration of this dispersion was 40% by weight.

(Adjustment of colorant dispersion (1))
・ Carbon black (Mogal L: Cabot): 60g
・ Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.): 6g
・ Ion exchange water: 240g
The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer (colorant (carbon) having an average particle size of 250 nm. Black) A colorant dispersant (1) in which particles were dispersed was prepared.

(Adjustment of colorant dispersion (2))
Cyan pigment (CI pigment blue 15: 3): 60 g
-Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5g
・ Ion exchange water: 240g
The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant (Cyan having an average particle size of 250 nm) Pigment) A colorant dispersant (2) in which particles were dispersed was prepared.

(Adjustment of colorant dispersion (3))
Magenta pigment (CI Pigment Red 122): 60 g
-Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5g
・ Ion exchange water: 240g
The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant (Magenta) having an average particle size of 250 nm. Pigment) A colorant dispersant (3) in which particles were dispersed was prepared.

(Adjustment of colored dispersion (4))
Yellow pigment (CI pigment yellow 180): 90 g
-Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.): 5g
・ Ion exchange water: 240g
The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant having an average particle size of 250 nm (Yellow) Pigment) A colorant dispersant (4) in which particles were dispersed was prepared.

(Release agent dispersion)
Paraffin wax (HNP0190: Nippon Seiwa Co., Ltd., melting point 85 ° C.): 100 g
Cationic surfactant (Sanisol B50: manufactured by Kao Corporation): 5 g
・ Ion exchange water: 240g
The above components were dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer, and the average particle size was 550 nm. A release agent dispersion in which the mold agent particles were dispersed was prepared.

<Adjustment of toner mother particle K1>
-Resin fine particle dispersion: 234 parts-Colorant dispersion (1): 30 parts-Release agent dispersion: 40 parts-Polyaluminum hydroxide (Pho2S manufactured by Asada Chemical Co., Ltd.): 0.5 parts-Ion exchange water : 600 parts The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then stirred at 40 ° C while stirring the flask in an oil bath for heating. Until heated.

After maintaining at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a volume average particle diameter of 4.5 μm were formed. Further, the temperature of the heating oil bath was raised and maintained at 56 ° C. for 1 hour, and the volume average particle size was 5.3 μm. Thereafter, 26 parts by weight of the resin fine particle dispersion was added to the dispersion containing the aggregate particles, and then the temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes.
The dispersion containing the aggregated particles is added with 1N sodium hydroxide to adjust the pH of the system to 5.0, and then the stainless steel flask is sealed and heated to 95 ° C. while stirring with a magnetic seal. And held for 4 hours. After cooling, the toner base particles were separated by filtration, washed four times with ion exchange water, and then lyophilized to obtain toner base particles K1. The volume average particle size of the toner base particles K1 is 6.2 μm, and the shape factor SF is 109.

<Adjustment of toner base particle C1>
Toner base particles C were obtained in the same manner as in the preparation of toner base particles K1, except that the color particle dispersion (2) was used instead of the color particle dispersion (1). The toner base particles C1 had a volume average particle diameter of 6.1 μm and an average shape factor SF of 110.

<Adjustment of toner mother particle M1>
Toner base particles M1 were obtained in the same manner as in the preparation of toner base particles K1, except that the color particle dispersion (3) was used instead of the color particle dispersion (1). The toner base particles M1 had a volume average particle diameter of 6.0 μm and an average shape factor SF of 114.

<Adjustment of toner base particle Y1>
Toner base particles Y1 were obtained in the same manner as in the preparation of toner base particles K1, except that the color particle dispersion (4) was used instead of the color particle dispersion (1). The toner base particle Y1 has a volume average particle diameter of 6.0 μm and an average shape factor SF of 108.

[Manufacture of carriers]
Ferrite particles (average particle size: 50 μm): 100 parts Toluene: 14 parts Styrene / methacrylate copolymer (component ratio (weight ratio): 90/10): 2 parts Carbon black (R330: manufactured by Cabot Corporation) : 0.2 part First, the above components excluding ferrite particles were stirred with a stirrer for 10 minutes to prepare a dispersed coating solution for coating the core material, and then the coating solution and ferrite particles were vacuum degassed kneader The mixture was stirred at 60 ° C. for 30 minutes, depressurized while being further heated, degassed, and dried to obtain a carrier. This carrier had a volume resistivity of 10 ¹¹ Ωcm at an applied electric field of 1000 V / cm.

Using K1, C1, M1, and Y1 as toner base particles, several types of external additives are added to 100 parts by weight of toner so that the combinations shown in Table 1 below are used, and the peripheral speed is 30 m / s × 15 using a 5 L Henschel mixer. After blending for 5 minutes, coarse particles were removed using a sieve having an opening of 45 μm, and toners 1 to 7 having different compositions of external additives were obtained.
Further, 100 parts of the carrier and 5 parts of the toner are stirred with a V-blender at 40 rpm × 20 minutes, and sieved with a sieve having a mesh opening of 212 μm, whereby developers 1 to 7 using the respective toners 1 to 7 are used. Got.

In addition, the cross-linked acrylic (resin) of the spherical fine powder 1 and the spherical fine powder 2 in Table 1 means methyl methacrylate / 1,1,1-trimethylolpropane trimethacrylate. The average particle diameters of the spherical fine powder 1 and the spherical fine powder 2 are 70 nm and 160 nm, respectively, and the shape factors SF ′ are 115 and 120, respectively.
Further, spherical fine powder 3 (SiO ₂ ) is obtained by subjecting silica sol obtained by the sol-gel method to HMDS (hexamethyldisilazane) treatment, drying and pulverizing, to obtain a specific gravity of 1.50, an average particle diameter of 140 nm, and a shape factor SF. 'Is 105 spherical monodisperse silica.
In addition, the average particle diameter and shape factor SF ′ of these spherical fine powders were obtained using FE-SEM as described above.

-Image forming device-
The image forming apparatus used for the evaluation is based on the Docu Center Color 400 manufactured by FUJI XEROX having the same configuration as that of FIG. 1 except that a blade cleaner is provided instead of the conductive fur brush. (A) A modified machine with a conductive fur brush (rotating brush) attached to the space where the blade cleaner was installed (the main part is the configuration shown in FIG. 1), (B) two conductive fur brushes (rotating brush) 3 types were used: a modified machine (main part shown in FIG. 2) attached with a fixed brush) and (C) a modified machine (main part shown in FIG. 4) from which the blade cleaner was removed. Note that the normal polarity of the toner in these modified machines is a negative polarity.

The conductive fur brush (rotating brush) is Beltron B12N (manufactured by Kanebo Co., Ltd.), the fiber thickness is 2 denier (diameter φ15.6 μm), the brush hair density is 12 × 10 ³ / inch ² (1.86) × 10 ⁷ pieces / m ² ) and a bristle length of 3 mm (including the adhesive layer)), and the amount of penetration with respect to the photosensitive member was set to 0.5 mm. The rotation direction of the rotating brush was opposite to the rotating direction of the photosensitive member, the peripheral speed ratio with respect to the photosensitive member was set to 1.0, and the voltage applied to the rotating brush was adjusted as appropriate between -0.8 to -1.2 Kv.

The fixed brush uses fibers of the same material as the rotating brush, and the brush bristle density is 40 × 10 ³ / inch ² (6.20 × 10 ⁷ / m ² ), and the bristle length is 5.5 mm (including the adhesive layer). ), The entry amount to the photosensitive member was set to 0.5 mm, the contact width was set to 5 mm, and the voltage applied to the fixed brush was + 200V.

The charging roll is a φ10 mm soft roll (manufactured by Suzuka Fuji Xerox Co., Ltd.). The applied voltage to the charging roll is a DC component of −570 V, and the AC current is constant so that the current value between the photoconductor and the charging roll is 0.8 mA. The electric field was controlled. The frequency of the AC electric field is 614 Hz.
Further, in order to further improve the transfer efficiency, the speed difference between the photosensitive member and the intermediate transfer belt is set to 3% in the transfer portion. The ratio of the intermediate transfer belt speed to the photosensitive member peripheral speed (intermediate transfer belt speed / photosensitive member peripheral speed) was set to 1.03. Further, a cleaning cycle for cleaning the toner of reverse polarity accumulated in the charge adjusting brush was provided at a rate of once per 100 sheets.
At that time, -400 V is applied to the rotating brush, and + charged toner is discharged onto the photosensitive member. At this time, only an AC electric field is applied to the charging roll, and no DC voltage is applied. Further, the polarity of the transfer electric field was reversed, and the toner was transferred onto the intermediate transfer belt, and collected by a blade cleaner attached to the outer peripheral surface of the intermediate transfer belt.

Using the image forming apparatus having the main parts described above having the configurations shown in FIGS. 1, 2, and 4, the applied voltage of the rotating brush, the photosensitive member, and the toner with the external additive composition changed are as follows. An image formation test was performed in combination as shown in Table 2.
In the image formation test, 100,000 sheets of images were formed under low temperature and low humidity (10 ° C., 15% RH) in the full color mode, and then 100,000 sheets of images were formed under high temperature and high humidity (28 ° C., 85% RH). At this time, the toner recoverability, scratches on the photoreceptor surface, photoreceptor filming (toner fusion), contact charging roll contamination, and image blur were observed. The results are shown in Table 3.

-Evaluation method-
In addition, the evaluation method and evaluation criteria of each evaluation item shown in Table 3 are as follows.
[Toner recovery (ghost)]
Since the toner that is not collected by the developing machine appears in the image as a ghost phenomenon, a solid chart and a vertical line chart of three color superpositions are flowed as a stress chart to evaluate each ghost. Judgment criteria are as follows.
A: No ghost even on the stress chart.
○: There is no ghost in the solid chart, and a slight ghost is seen in the stress chart, but it disappears in the second cycle.
Δ: No ghost in the solid chart, ghost is seen in the stress chart, and does not disappear in the second cycle.
X: A level that clearly shows a ghost even in a solid chart, and is judged to be NG in terms of image quality.

[Photoconductor scratches]
The photoreceptor scratches were evaluated by measuring the 10-point average roughness (Rz) with a surface roughness meter (Surfcom 1400A manufactured by Tokyo Seimitsu Co., Ltd.). Judgment criteria are as follows.
○: Rz is 3.0 μm or less.
Δ: Rz is more than 3.0 μm and less than 3.5 μm.
X: Rz is 3.5 μm or more (white streaks appear on the image).

[Fused toner on photoconductor (photoconductor filming)]
Filming on the photoreceptor after running was judged by sensory evaluation by visual observation. Judgment criteria are as follows.
○: No sticking at all.
Δ: A level that does not affect the image quality, although there is some sticking.
X: The surface is clearly fixed, and appears as color streaks and white streaks in the image quality.

[Charger contamination]
Contamination of the contact charger with toner after running was judged by sensory evaluation by visual observation. Judgment criteria are as follows.
○: No sticking at all.
Δ: A level that does not affect the image quality, although there is some sticking.
X: The surface is clearly fixed, and appears as white streaks in the image quality.

[Image blur under high temperature and high humidity]
Image blur was evaluated as follows. First, after 100,000 sheets of halftone images (image density 30%) have been printed under a high temperature and high humidity environment (28 ° C., 85% RH), the surface of the photoreceptor is removed to remove water-soluble discharge products. Only a part was wiped with water.
Thereafter, a halftone image (image density of 30%) is printed again, and an image portion corresponding to a portion where the surface of the photosensitive member is wiped with water and a portion where the surface is not wiped with a reflection type density measuring device (X-rite). The density difference (ΔSAD) was measured and evaluated according to the following criteria.
Since image blur (character blur) corresponds to a density difference of a halftone image printed after wiping off the surface of the photoreceptor, this evaluation method was used instead. Note that white spots are caused by discharge products as in the case of image blur, and therefore, substitute evaluation was performed by evaluating image blur that is easy to quantitatively evaluate.
○: ΔSAD is 0.15 or less.
Δ: ΔSAD is more than 0.15 and less than 0.4.
X: ΔSAD is 0.4 or more.

1 is a schematic cross-sectional view illustrating a configuration example of an image forming apparatus of the present invention. FIG. 6 is a schematic cross-sectional view showing another configuration example of the image forming apparatus of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration example of a latent image carrier used in the image forming apparatus of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus used in a comparative example.

Explanation of symbols

1 Latent image carrier (photoreceptor)
11 Conductive substrate 12 Undercoat layer 13 Charge generation layer 14 Charge transport layer 15 Protective layer (outermost surface layer)
16 Photosensitive layers 100, 101, 102 Image forming apparatus 110 Latent image carrier (photosensitive member)
111 Charging roll 112 Exposure device 113 Developer 113a Developing roll (magnetic brush carrier)
114 Transfer roller 116 Conductive fur brush (rotary brush)
118 Conductive fur brush (fixed brush)
120 Intermediate transfer belt

Claims (6)

A charging step of charging the surface of the latent image carrier, a latent image forming step of irradiating the charged surface of the latent image carrier with light to form a latent image, and a developer containing toner supplied from the developing means. A developing step of developing the latent image to form a toner image; a transferring step of transferring the toner image to a transfer target; and a surface of the latent image carrier after the transfer of the toner image; A residual toner charged to a polarity opposite to the polarity of the supplied toner is temporarily collected by a conductive fur brush to adjust the charging state, and the residual toner collected by the conductive fur brush is removed from the latent toner. At least a toner recovery step of discharging to the surface of the image carrier and recovering by a developing means,
The image forming method for discharging the residual toner collected by the conductive fur brush to the surface of the latent image carrier after reversing its polarity by the conductive fur brush,
The latent image carrier surface contains a resin having a crosslinked structure, and the toner contains spherical inorganic fine powder and / or organic fine powder having an average particle diameter in the range of 70 nm to 200 nm. Forming method.   The image forming method according to claim 1, wherein the surface of the latent image carrier includes a compound having a charge transporting ability.   The resin having the crosslinked structure is at least one resin selected from a phenolic resin obtained by crosslinking a phenol derivative having a methylol group and a siloxane resin having a crosslinked structure. 3. The image forming method according to 2.   The resin having a crosslinked structure includes a structural unit having a charge transporting ability including at least one selected from a hydroxyl group, a carboxyl group, an alkoxysilyl group, an epoxy group, a thiol group, and an amino group. 4. The image forming method according to 3. The image forming method according to claim 1, wherein a shape factor SF of the toner defined by the following formula (1) is in a range of 100 to 140. 6.
Formula (1) SF = 100 × π × ML ² / 4A
[In the formula (1), SF represents the shape factor of the toner, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles. ]   A latent image carrier comprising a resin having a crosslinked structure on the surface, a charging means for charging the surface of the latent image carrier, and a latent image for forming a latent image by irradiating the charged surface of the latent image carrier with light. Forming means; developing means for developing the latent image with a developer containing toner to form a toner image; transfer means for transferring the toner image to a transfer target; and the latent image after transferring the toner image. And a conductive fur brush having at least a function of collecting residual toner remaining on the surface of the carrier and charged to a polarity opposite to that of the toner supplied from the developing unit and adjusting a charged state. An image forming apparatus that forms an image by using the image forming method according to any one of claims 1 to 5.

Images