JP2009003157A - Image forming apparatus, image forming method, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method, an image forming apparatus and, a process cartridge having such durability as to stably realize high-quality images over a long period of time by stable transfer performance even when applied to a smaller high-speed image forming process. <P>SOLUTION: The image forming apparatus using a normal developing system includes: at least an image carrier; a charging means to charge the image carrier; an electrostatic latent image forming means to form an electrostatic latent image on the charged surface of the image carrier with resolution of ≥1,200 dpi; and a developing means to develop the electrostatic latent image as a toner image, wherein a time T<SB>ed</SB>(ms) in which an arbitrary position on the image carrier moves from a position just opposite to the electrostatic latent image forming means to a position just opposite to the developing means and a transit time t<SB>T</SB>(ms) of the image carrier satisfy the expression (A): T<SB>ed</SB><t<SB>T</SB><1.3×T<SB>ed</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming method, an image forming apparatus, and a process cartridge.

  In image formation by an image forming apparatus such as a copying machine, printer, or facsimile using an electrophotographic method, the surface of an image carrier (hereinafter also referred to as an electrophotographic photosensitive member or a photosensitive member) is uniformly charged by a charging device, An electrostatic latent image is formed by exposing the surface of the charged photoreceptor in accordance with the original image or the input image signal. The electrostatic latent image is developed by a developing device to form a toner image, the toner image is transferred to a transfer material by a transfer device, and the toner image is fixed on the transfer material as a permanently fixed image by a fixing device. Is output.

The transfer residual toner remaining on the surface of the photoreceptor after the image formation is removed by a cleaning device. The cleaning process by the cleaning device is a process in which the cleaning member is pressed against the photosensitive member to stop the transfer residual toner, and is scraped off and collected in a waste toner container. A blade-type cleaning member is used. Such a cleaning member is in direct contact with the photosensitive member, so that it is excellent in collecting residual toner, lasting for a long time, and exhibits good cleaning even when a large amount of residual toner is generated. To do.
On the other hand, however, it has been pointed out that the photoreceptor is worn (short-lived), that waste toner needs to be processed, and that the apparatus is inevitably enlarged to include the cleaning container.

Accordingly, simultaneous development cleaning (or cleaner-less) has been proposed as a waste toner-less system from the viewpoints of ecology, photoreceptor life, apparatus miniaturization, and effective use of toner.
In the simultaneous development cleaning, the toner remaining on the photosensitive member after transfer is collected by a fog removing bias (fogging potential difference Vback, which is a potential difference between the DC voltage applied to the developing device and the surface potential of the photosensitive member) at the time of development after the next step. It is a method to do. To put it simply, this eliminates the cleaner, and the transfer residual toner on the photosensitive member after transfer is removed from the photosensitive member by the developing device (developing device) by simultaneous development cleaning, and is collected and reused in the developing device. The image forming apparatus of the toner recycling process. According to this method, since the transfer residual toner is collected by the developing device and reused after the next step, waste toner can be eliminated and maintenance can be facilitated. In addition, the cleaner-less has a great space advantage, and the image forming apparatus can be further downsized.

  However, in such a simultaneous development cleaning method, since reversal development in which the toner polarity and the photosensitive member charging polarity are the same polarity is used as a development method, the conventional analog type copying apparatus using regular development, etc. In principle, it was impossible to apply the simultaneous development cleaning method. In addition, when a laser or LED array is used as the exposure means, it is impossible in principle to apply the conventional simultaneous development cleaning method to so-called back scanning in which a portion corresponding to the background portion is exposed.

Therefore, a development simultaneous cleaning method that can be applied to a system using regular development in which the toner charging polarity and the photosensitive member charging polarity are opposite polarities has been desired.
For example, Patent Document 1 proposes simultaneous development cleaning using elastic deformation of an image carrier. In this simultaneous development cleaning, the untransferred developer is rolled by the slight deformation of the image carrier in the developing nip and the speed difference between the developer and the untransferred developer to reduce the adhesive force. In order to shield the charge of the agent, an aggregate in which the periphery of the untransferred developer is surrounded by the developer is formed. In this case, it is difficult to maintain a high quality image for a long time only by elastic deformation of the image carrier.

On the other hand, in order to solve the technical problem of image carrier wear in such a simultaneous development cleaning method, an image forming apparatus using a first charging unit and a second charging unit is described in Patent Document 2. In Patent Document 2, by providing the second charging means, it is possible to charge the residual toner to the same polarity as the charging polarity of the toner image without changing the polarity of the potential of the image carrier. A statement that the transfer residual toner is not charged with a negative polarity as a whole, is removed from the black portion, and does not remain on a white background, so that simultaneous development cleaning using regular development can be established. There is.
However, in this method, the compactness of the apparatus has not been improved, and since there are two charge polarity control members around the image carrier, it is necessary to increase the size of the apparatus, and no cleaner is required. This has deviated from the original technical concept of a cleaner-less compact image forming apparatus that does not generate waste toner.

  In a system such as the above-described elastic deformation of the image carrier and simultaneous development cleaning by charge polarity control, the image forming apparatus has not been downsized. Further, in the development simultaneous cleaning that essentially does not have a cleaning device, it is essential to have a structure in which the surface of the photoreceptor is rubbed with toner and a toner carrier, and for this reason, toner deterioration due to long-term use, toner carrier surface deterioration, Since the surface of the photoreceptor is deteriorated or worn, and the durability is easily deteriorated, the prior art cannot sufficiently solve the problem, and it has been desired to achieve both the fixing property and the durability. At the same time, where speeding up of image formation is desired at the same time, in the simultaneous development cleaning of a device with a faster process speed, charge control of the residual toner before recovery for improving the recoverability of the residual toner during development, and control of the recovered toner In terms of maintaining the stability of development during reuse, the prior art does not provide a sufficient solution.

From the above, in order to cope with ecology and cost, a compact image forming apparatus in which a cleaner for a photoreceptor is essentially unnecessary and waste toner is not generated is not yet known. In addition, in the regular development type image forming method, there has not yet been found a prior art in which a sufficient solution has been made to the problem of downsizing a high-speed image forming apparatus.
JP 2001-175084 A Japanese Patent No. 3155915

An object of the present invention is to provide an image forming method, an image forming apparatus, and a process having durability capable of stably realizing a high-quality image over a long period of time by stable transfer performance even when applied to a smaller and faster image forming process. To provide a cartridge.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method, an image forming apparatus, and a process cartridge that are excellent in transferability, have little transfer residual toner, do not cause transfer defects even in a regular development method, or suppress these phenomena. There is.
It is a further object of the present invention to provide an image forming method, an image forming apparatus, and a process cartridge that essentially have no cleaning device.

The present invention is an image forming method, an image forming apparatus, and a process cartridge characterized by the following means.
(1) At least an image carrier, a charging unit for charging the image carrier, an electrostatic latent image forming unit for forming an electrostatic latent image on a charging surface of the image carrier with a resolution of 1200 dpi or more, and the electrostatic latent In a regular development type image forming apparatus having a developing means for developing an image as a toner image,
The time required for an arbitrary position on the image carrier to move from the position facing the electrostatic latent image forming means to the position facing the developing means is T _ed (ms), and the transit time of the image carrier is t _{When T} (ms), T _ed satisfies the following formula (A).
_{T ed <t T <1.3 ×} T ed ... formula (A)

(2) The image forming apparatus according to (1), wherein a plurality of image forming elements having at least an image carrier, a charging unit, an electrostatic latent image forming unit, and a developing unit are used.
(3) The electrostatic latent image forming means is a multi-beam scanning optical system having scanning optical means for forming a plurality of laser beams on the image carrier (1) or (2) The image forming apparatus described in 1.
(4) The image forming apparatus according to (3), wherein the light source of the multi-beam scanning optical system is three or more surface-emitting laser arrays.
(5) The light source of the multi-beam scanning optical system is a surface-emitting laser array having three or more surface-emitting laser arrays in which a plurality of light-emitting points are two-dimensionally arranged. The image forming apparatus according to (4).

（一般式（１）中、Ｘ及びＹは、それぞれ独立に、下記一般式（２）

（一般式（２）中、Ｒ₃は、水素原子、アリール基又はアルキル基であり、Ｒ₄、Ｒ₅、Ｒ₆、Ｒ₇及びＲ₈は、それぞれ独立に、水素原子、水酸基、アルキル基、アルコキシ基、シアノ基、ジアルキルアミノ基、ニトロ基、ハロゲン基、又はハロゲン化アルキル基であり、Ｚは、置換基を有してもよい炭素環式芳香族又は置換基を有してもよい複素環式芳香族を構成するのに必要な原子団である。）
で示されるカプラー残基であり、Ｒ₁及びＲ₂は、それぞれ独立に、水素原子、アルキル基、アルコキシ基、シアノ基又はハロゲン基である。 (6) The image carrier has at least a photosensitive layer containing a charge generating substance, and the charge generating substance contains an azo compound represented by the following general formula (1) (1) The image forming apparatus according to any one of (5) to (5).

(In general formula (1), X and Y are each independently the following general formula (2)

(In General Formula (2), R ₃ is a hydrogen atom, an aryl group or an alkyl group, and R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a hydroxyl group, or an alkyl group. , An alkoxy group, a cyano group, a dialkylamino group, a nitro group, a halogen group, or a halogenated alkyl group, and Z may have a carbocyclic aromatic group or a substituent that may have a substituent. It is an atomic group necessary for constituting a heterocyclic aromatic.)
And R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen group.

(7) The image forming apparatus according to (6), wherein X and Y of the azo compound are mutually different coupler residues.
(8) The image carrier has a photosensitive layer containing at least a charge generating material, and the charge generating material has a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using CuKα characteristic X-rays. ) Strong diffraction peaks at 9.4 °, 9.6 ° and 24.0 °, diffraction peak at 27.2 ° is the strongest, 7.3 ° as the lowest angle diffraction peak Crystal of titanyl phthalocyanine having a diffraction peak at 7.3 °, no diffraction peak between the diffraction peaks at 9.4 °, and no diffraction peak at 26.3 ° The image forming apparatus according to any one of (1) to (5), wherein:

(9) The image forming apparatus according to any one of (1) to (8), wherein the image carrier has a protective layer as an outermost layer.
(10) The image forming apparatus according to (9), wherein the protective layer contains at least one kind selected from inorganic pigments and metal oxides having a specific resistance of 10 ¹⁰ Ω · cm or more.
(11) The protective layer is formed by curing at least a trifunctional or higher functional radical polymerizable compound having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure. The image forming apparatus according to (9), which is characterized.

（一般式（３）及び（４）中、Ｒ₁は、水素原子、ハロゲン基、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基、置換若しくは無置換のアリール基、シアノ基、ニトロ基、アルコキシ基、一般式
−ＣＯＯＲ₂
（式中、Ｒ₂は、水素原子、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基又は置換若しくは無置換のアリール基である。）
で示される官能基、一般式
−ＣＯＹ
（式中、Ｙは、ハロゲン基である。）
で示される官能基又は一般式
−ＣＯＮＲ₃Ｒ₄
（式中、Ｒ₃及びＲ₄は、それぞれ独立に、水素原子、ハロゲン基、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基又は置換若しくは無置換のアリール基である。）
で示される官能基であり、
Ａｒ₁及びＡｒ₂は、それぞれ独立に、置換又は無置換のアリーレン基であり、Ａｒ₃及びＡｒ₄は、それぞれ独立に、置換又は無置換のアリール基であり、Ｘは、単結合、置換若しくは無置換のアルキレン基、置換若しくは無置換のシクロアルキレン基、置換若しくは無置換のオキシアルキレン基、酸素原子、硫黄原子又はビニレン基であり、Ｚ₁は、置換若しくは無置換のアルキレン基、置換若しくは無置換のオキシアルキレン基又は一般式
−ＣＯＯＲ₆−
（式中、Ｒ₆は、アルキレン基である。）
で示される官能基であり、ｍは、それぞれ独立に、０以上３以下の整数である。） (12) The image according to (11), wherein the monofunctional radically polymerizable compound having the charge transporting structure is one or more of compounds represented by the following general formulas (3) and (4): Forming equipment.

(In the general formulas (3) and (4), R ₁ represents a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a cyano group, a nitro group, Group, alkoxy group, general formula -COOR ₂
(Wherein R ₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by the general formula -COY
(In the formula, Y is a halogen group.)
Or a functional group represented by the general formula —CONR ₃ R ₄
(Wherein R ₃ and R ₄ are each independently a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by
Ar ₁ and Ar ₂ are each independently a substituted or unsubstituted arylene group, Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group, and X is a single bond, substituted or An unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted oxyalkylene group, an oxygen atom, a sulfur atom or a vinylene group, and Z ₁ is a substituted or unsubstituted alkylene group, substituted or unsubstituted Substituted oxyalkylene group or general formula —COOR ₆ —
(In the formula, R ₆ is an alkylene group.)
And m is independently an integer of 0 or more and 3 or less. )

（一般式（５）中、ｏ、ｐ及びｑは、それぞれ独立に、０又は１であり、Ｒ₂は、水素原子又はメチル基であり、Ｒ₃及びＲ₄は、それぞれ独立に、炭素数が１以上６以下のアルキル基であり、ｓ及びｔは、それぞれ独立に、０以上３以下の整数であり、Ｚ₂は、単結合、メチレン基、エチレン基又は構造式

で示される官能基である。） (13) The image forming apparatus according to (11), wherein the monofunctional radically polymerizable compound having the charge transporting structure is one or more compounds represented by the following general formula (5).

(In the general formula (5), o, p and q are each independently 0 or 1, R ₂ is a hydrogen atom or a methyl group, and R ₃ and R ₄ are each independently a carbon number. Is an alkyl group of 1 to 6 and s and t are each independently an integer of 0 to 3, Z ₂ is a single bond, a methylene group, an ethylene group or a structural formula

It is a functional group shown by. )

(14) The image forming apparatus according to any one of (11) to (13), wherein the protective layer curing means is heating or light energy irradiation means.
(15) The image forming element having at least the image carrier, the charging unit, the electrostatic latent image forming unit, and the developing unit is a cleanerless image forming element that does not have an image carrier cleaning device ( The image forming apparatus according to any one of 1) to (14).
(16) A process cartridge that integrally supports at least one unit selected from the group consisting of an image carrier, a charging unit, and a developing unit, and is detachable from the main body of the image forming apparatus. A process cartridge for use in the image forming apparatus according to any one of the above.

(17) At least an image carrier, a charging step for charging the image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on a charging surface of the image carrier with a resolution of 1200 dpi or more, and the electrostatic latent In an image forming method of a regular development system, which has a development step of developing an image as a toner image,
The time required for an arbitrary position on the image carrier to move from the position facing the electrostatic latent image forming unit to the position facing the developing unit is T _ed (ms), and the transit time of the image carrier is t An image forming method, wherein T _ed satisfies the following formula (A) where _T (ms).
_{T ed <t T <1.3 ×} T ed ... formula (A)

(18) The image forming method according to (17), wherein a plurality of image forming elements having at least an image carrier, a charging step, an electrostatic latent image forming step, and a developing step are used.
(19) The electrostatic latent image forming step is a multi-beam scanning optical system having a scanning optical step of forming a plurality of laser beams on the image carrier (17) or (18) The image forming method described in 1.
(20) The image forming method according to (19), wherein the light source of the multi-beam scanning optical system is three or more surface-emitting laser arrays.
(21) The light source of the multi-beam scanning optical system is a surface emitting laser array having three or more surface emitting laser arrays, in which a plurality of light emitting points are two-dimensionally arranged. The image forming method according to (20).

That is, according to the present invention, in an image forming method or an image forming apparatus of a regular development system, the time required for an arbitrary position on the image carrier to move from a position facing the electrostatic latent image forming unit to a position facing the developing unit. When T _ed (ms) and the transit time of the image carrier is t _T (ms), the following equation (A)
_{T ed <t T <1.3 ×} T ed ... formula (A)
By satisfying the above, transfer failure in the transfer process is suppressed, and occurrence of image failure is prevented.

  According to the study by the present inventors, it is not necessary to increase the transfer voltage, and if the control is performed so as to satisfy the above formula (A), the toner can be prevented from remaining on the photoreceptor for a long time. In addition, the photosensitive member can be uniformly charged, and as a result, high image quality can be achieved even without a cleaner device for collecting the transfer residual toner.

  In general organic photoreceptors, when the exposure-development time is shortened in the image forming apparatus, the exposed portion potential is somewhat increased. With respect to the time dependency between exposure and development of the potential of the exposed portion, it is possible to observe the time dependency of the inclination that is considered as the inflection point. The shorter the exposure time is, the shorter the exposure-to-development time is shortened. The inventor has found that there is a good correspondence between this time dependency and toner transferability. And it discovered that the output of defective images, such as a fog, can be prevented by using the time dependence of this exposure part potential rise within a specific range. Such a defective image is often eliminated by increasing the printing speed. Therefore, it is considered that the defective image is caused by the time response of the surface potential light attenuation of the photoconductor.

Here, the time response evaluation of the surface potential light attenuation of the electrophotographic photosensitive member will be described.
As a method for evaluating the time response of the surface potential light decay of the electrophotographic photosensitive member, for example, a charge transport material found in JP-A-10-115944 or JP-A-2001-312077, or a resin comprising this and a binder resin Membranes are often estimated from the time of flight (TOF) method. This is a useful method in designing the formulation of the photoreceptor. However, the charge transport conditions of the photoconductor used in the apparatus and the charge transport conditions by the TOF method are such that the former changes the electric field strength in the film from time to time after exposure, whereas the latter shows the electric field strength. The difference is pointed out. In addition, for the multilayer photoconductor, the influence of charge generation from the charge generation layer upon exposure and injection behavior from the charge generation layer to the charge transport layer on the charge transport is also reflected in the measured value by the TOF method. No.

  Further, as a method for directly evaluating the responsiveness of the photoconductor, for example, the surface potential change of the photoconductor after the pulsed light irradiation disclosed in JP-A-2000-305289 is recorded at high speed using a high-speed surface electrometer, A method for measuring the response time required to reach the potential has been proposed. This method is generally referred to as a xerographic time of flight (XTOF) method. This method can be said to be useful as an evaluation means for solving the problems of the TOF method. However, in this method, the light source used for measurement is often different from the exposure means used in the image forming apparatus, and has a side that cannot be said to be a direct measurement method.

On the other hand, by using the photoconductor characteristic evaluation apparatus described in Japanese Patent Application Laid-Open No. 2000-275872, an arbitrary position of the photoconductor moves from the position facing the electrostatic latent image forming unit to the developing unit. A time T _ed (ms) for moving to a directly facing position (hereinafter referred to as process time for simplicity) is set, and an exposure unit for the exposure amount of the photosensitive member output from the electrostatic latent image forming means such as an LD It is possible to grasp the potential relationship (light attenuation curve).
In this apparatus, when the change in the exposed portion potential at a position directly opposite to the developing means when the process time is changed, a bending point can be found in the relationship of the exposed portion potential with respect to the process time. For convenience, the process time at this inflection point is referred to as actual machine transit time t _T (ms). A specific example is shown in FIG. According to this, it is possible to accurately grasp the relationship between the process time and the exposure portion potential, that is, the time response of the surface potential light attenuation of the electrophotographic photosensitive member. The transit time depends on the surface potential of the photoconductor and the thickness of the photoconductor before irradiation of writing light (in other words, depends on the electric field strength applied to the photoconductor). Accordingly, when measuring the transit time, a photoconductor having the same composition and the same film thickness as the photoconductor actually used is used, and the surface potential of the photoconductor before writing light irradiation is determined by the image forming apparatus in which the photoconductor is used. It is necessary to make the evaluation the same as the surface potential of the unexposed portion.

FIG. 2 also illustrates one method for determining the process time of the present invention. In FIG. 2, 1 is a photoconductor to be determined, 2 is a scorotron charging device as a charging means, 3 is an exposure device including a laser diode and an ND filter, 3L is light (exposure light), 14 Is an electrometer (potential probe) for measuring (reading) the surface potential of the photosensitive member provided at a position facing the developing means. The photoreceptor 1 is driven to rotate in the direction of the arrow. FIG. 2 illustrates an electrophotographic photosensitive member having a diameter of 30 mm.
In FIG. 2, the position where the light 3L is irradiated, that is, the exposure position and the potential measurement position by the electrometer 14 are set to 45 °.

In FIG. 2, the diameter of the photosensitive member 1 is 30 mm, and the angle formed by the exposure position, the electrophotographic photosensitive member center, and the potential measurement position is 45 °. Therefore, the moving speed of the surface of the photosensitive member is 270 [mm]. / S], the required process time is
(30π / 270) × (45 ° / 360 °) ≈44 ms
It becomes.

The toner image on the photosensitive member is subjected to Coulomb force toward the transfer device, and the toner image moves to the transfer material and is electrically restrained on the transfer material by the negative charge applied to the back of the transfer material.
On the other hand, as the diameter of the toner decreases, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photoconductor becomes larger than the Coulomb force applied to the toner particles during transfer. There is a tendency that the transfer residual toner increases. In the present invention, the transit time is related to the process time so as to satisfy the expression (A), and as a result, a high-quality image can be output by a cleaner-less machine.

The image forming apparatus of the present invention uses regular development in which the charging polarity of the toner and the charging polarity of the photoreceptor are opposite.
In the regular development system, the developer is transferred to the unexposed portion of the photoreceptor. In the transfer process, the developer is transferred to the transfer target. By defining the transit time of the photosensitive member within the range of the formula (A), the amount of toner particles transferred to the transfer target can be increased. The toner transferability could be stably controlled.

In the reversal development method, the residual toner is aligned with the same charging polarity as that of the developing toner in the charging step, so that simultaneous development cleaning is possible. However, in the case of regular development, the development simultaneous cleaning process is not established. The reason for this will be described in the case where positively charged toner is attached to a negatively charged unexposed portion. If there is positive transfer residual toner and the toner is negatively charged by corona charging, the polarity of the transfer residual toner is reversed (negative). When the toner is exposed to a laser beam and developed with positively charged toner with a developing bias applied thereto, the transfer residual toner of reverse (negative) polarity attached to the non-image area cannot be removed. Then, the transfer residual toner increases, and the positively charged toner is electrically attracted to and adhered to the transfer residual toner portion to cause fogging.
The transferred toner around the high potential portion where the toner in the unexposed portion is transferred (positive polarity) is surrounded by the transferred negative polarity toner. On the other hand, the untransferred toner (positive polarity) in the exposed portion adheres with the same adhesion force as in the case of reversal development because its mirror image power is determined by the absolute value of the charge.

By the way, when the photosensitive member transit time is made larger than the process time, the transfer residual toner having a large negative charge at the development step may have a slight decrease in the exposed portion potential between the development step and the transfer step. The net negative charge is further reduced accordingly.
In this way, when the retained charge of the transfer residual toner is apparently reduced, the mirror image force on the photosensitive member is reduced and the adhesion force is reduced. A coulomb force that attracts between the developing toner and the transfer residual toner works, and when the charge of the development toner becomes larger than the charge of the transfer residual toner, the suction force between the toners overcomes the mirror image force. As a result, the transfer residual toner is peeled off from the photoreceptor.
In the above process, in the case of regular development, when the simultaneous development cleaning is repeated, the transfer residual toners are piled up with the same polarity and become overcharged, and a strong mirror image force works and cannot be transferred. By defining the transit time of the photosensitive member within the range of (), the transfer residual toner does not accumulate in one charged row because the mirror image force on the photosensitive member is reduced in the transfer process, and the residual toner is easily peeled off. be able to.

  Furthermore, the system is preferably a cleanerless system that does not provide a cleaning process between the transfer process and the charging process. In other words, in order to cope with ecology and cost, it is recognized that the compact image forming apparatus of the regular development system in which a cleaner for the photoreceptor is essentially unnecessary and waste toner is not generated is recognized. Is preferable.

The process time (T _ed ) varies depending on the photosensitive drum diameter, line speed, and the like. On the other hand, the transit time (t _T ) changes by changing the film thickness of the charge transport layer of the photoreceptor, the amount of donor added to the resin binder, and the like. Thus, by independently designing the process and the photoconductor, it is possible to obtain an image forming apparatus that satisfies the formula (A). Conventional image forming apparatuses are designed to satisfy the relationship of T _ed > t _T and are different from the present invention in this respect.

The electrostatic latent image forming means is preferably a multi-beam scanning optical system having scanning optical means for forming a plurality of laser beams on the image carrier. As a result, high image quality can be maintained over a long period even on a high-speed machine with a high process speed.
In order to increase the resolution of the image, it is effective to reduce the particle diameter of the toner and reduce the spot diameter of the laser beam for image formation. In particular, in an ultra-high-quality machine targeted for printing pictorial images such as high-quality photographs, a resolution of 1200 dpi or more is required, and a technique for reducing the spot diameter to 30 μm or less is required. As a means for reducing the spot diameter of the laser beam, the relationship between the process time and the transit time can be obtained even when a high-speed machine using a multi-beam method as the electrostatic latent image forming means and using a high process speed is used. By setting the inside, a high-quality image can be obtained over a long period of time.

  The image carrier preferably has a protective layer as the outermost layer. Thereby, abrasion resistance can be improved.

  Therefore, according to the image forming apparatus of the present invention, it is possible to easily achieve high image quality of the image to be formed, increase the image forming speed, and reduce the size of the apparatus, and even if the image forming process is repeated over a long period of time. A good quality image can be obtained. For example, according to the image forming apparatus of the present invention, it is possible to form a high-resolution image quality having a recording density of 1200 dots / inch (dpi) or more over a long period of time.

As an exposure means used in laser beam printers and digital copying machines, a laser beam corresponding to an image signal is output from a semiconductor laser, reflected by a rotating polygon mirror, and irradiated onto the surface of the electrophotographic photosensitive member. To form an electrostatic latent image.
In the case of such exposure means using a laser beam, it is necessary to increase the scanning speed of the laser beam in order to achieve high definition (high image quality) and high speed of the output image with one laser beam. . However, since the rotational speed of the rotary polygon mirror is limited, it has been difficult to achieve high definition and high speed of the output image.

In order to improve such a problem, a method of scanning a plurality of laser beams on an electrophotographic photosensitive member (hereinafter referred to as “multi-beam method”) has been proposed. The multi-beam image forming apparatus is considered to be effective for speeding up the image forming process because of the following advantages 1) to 3).
1) In the case of an image forming apparatus using n (n is a natural number) laser beams, scanning is performed when the scanning speed of the laser beam and the printing speed are set equal to the case of using a single laser beam. The line density can be increased n times, and high-resolution image recording is possible.
2) When the scanning speed of the laser beam and the density of the scanning line are set equal to a single case, the printing speed can be increased n times.
3) When the printing speed and the scanning density of the laser beam are set equal to the single case, the scanning speed of each laser beam is lowered (that is, the reflected laser beam is irradiated on the surface of the electrophotographic photosensitive member by reflecting the laser beam). The number of rotations of the rotating polygon mirror for forming the electrostatic latent image can be reduced by 1 / n), and the mechanism for rotating the rotating polygon mirror can be simplified to reduce the cost. Become.

  As such a multi-beam type image forming apparatus, there is known an image forming apparatus using an edge-emitting laser that emits a laser beam from an end face orthogonal to a substrate surface of a semiconductor substrate (for example, Japanese Patent Laid-Open No. 2002-107988). No., JP 2002-303997 A). However, the edge-emitting laser has a problem that it is difficult to finely adjust the interval between the scanning lines, and it is not easy to increase the number of laser beams. The speedup of was insufficient.

  Therefore, as a multi-beam image forming apparatus, a plurality of laser beams are deflected and simultaneously scanned on a scanning object such as an electrophotographic photosensitive member, and a plurality of scanning lines are scanned by one main scanning. An image forming apparatus configured to form an image by performing a surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser) that can be easily arrayed as a light source of an exposure apparatus, and the number of laser beams to be scanned simultaneously (laser By increasing the number of scanning lines simultaneously scanned by the beam, it is possible to achieve high image quality and high image formation speed. (For example, see JP-A-5-294005).

As described above, in the present invention, at least an image carrier, a charging unit for charging the surface of the image carrier, and a latent image for forming an electrostatic latent image on the charging surface of the image carrier with a resolution of 1200 dpi or more. In an image forming apparatus of a normal development system provided with a forming means and a developing means for developing the electrostatic latent image as a toner image, and a process cartridge mounted on such an image forming apparatus, the transit of the image carrier By controlling the time, it was possible to prevent the toner from remaining on the image carrier and to improve the toner transferability in the transfer means. As a result, uniform charging was sustained over the long term, and high image quality was achieved.
Furthermore, it can be applied to an image forming method having a high process speed at a low cost without adding a simultaneous development cleaning process.

The image forming apparatus and the image forming method of the present invention will be described below.
The image forming apparatus of the present invention includes at least an image carrier, a charging unit for charging the image carrier, and an electrostatic latent image forming unit for forming an electrostatic latent image on a charging surface of the image carrier with a resolution of 1200 dpi or higher. An image forming apparatus of a normal development system having a developing means for developing the electrostatic latent image as a toner image, wherein an arbitrary position on the image carrier is directly opposite to the electrostatic latent image forming means T _ed satisfies the following formula (A), where T _ed (ms) is the time taken to move to the position facing the developing means, and t _T (ms) is the transit time of the image carrier.
_{T ed <t T <1.3 ×} T ed ... formula (A)

The image forming method of the present invention includes at least an image carrier, a charging step for charging the image carrier, and an electrostatic latent image forming step for forming an electrostatic latent image on the charging surface of the image carrier with a resolution of 1200 dpi or higher. In an image forming method of a normal development system, which has a developing step of developing the electrostatic latent image as a toner image, an arbitrary position on the image carrier is moved from a position directly facing the electrostatic latent image forming means. Assuming that the time for moving to the position facing the developing means is T _ed (ms) and the transit time of the image carrier is t _T (ms), T _ed satisfies the above formula (A).

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the charging step can be performed by the charging means, and the electrostatic latent image forming step is the electrostatic latent image forming step. The developing step can be performed by the developing unit.

(1) Example of Image Forming Apparatus Members having substantially the same function will be described using the same reference numerals throughout the drawings.
1) Monochrome image forming apparatus 100
FIG. 3 is a block diagram of a main part of a monochrome printer which is an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus of this example is a laser beam printer (digital copying machine) using a transfer type electrophotographic process, a contact charging system, a regular development system, and a process cartridge system.
The image forming apparatus 100 shown in FIG. 3 includes a photoconductor 1, and the photoconductor 1 can be rotated in a direction indicated by an arrow A at a predetermined rotation speed by a driving device (not shown). A charger 2 is provided substantially above the photoreceptor 1 as a charging means for charging the outer peripheral surface of the photoreceptor 1.
Further, an exposure device (laser beam scanning device) 3 is arranged as an electrostatic latent image forming unit substantially above the charger 2. Although details will be described later, the exposure device 3 modulates a plurality of laser beams emitted from a light source in accordance with an image to be formed, deflects them in the main scanning direction, and is charged by a charger 2. Are scanned in parallel with the axis of the photoreceptor 1.

A developing device 4 is disposed on the side of the photosensitive member 1 as developing means. The developing device 4 can be supplied with black toner stored in a toner cartridge.
An endless intermediate transfer belt 5 is disposed substantially below the photosensitive member 1. The intermediate transfer belt 5 is wound around rollers 10, 11, and 12, and is disposed so that the outer peripheral surface is in contact with the outer peripheral surface of the photoreceptor 1. The rollers 10 to 12 rotate when a driving force of a motor (not shown) is transmitted to rotate the intermediate transfer belt 5 in the direction of arrow B.

A transfer device 6 is disposed on the opposite side of the photoreceptor 1 with the intermediate transfer belt 5 interposed therebetween. The toner image formed on the outer peripheral surface of the photoreceptor 1 is transferred to the image forming surface of the intermediate transfer belt 5 by the transfer device 6.
A transfer unit 7 is arranged on the opposite side of the roller 12 with the intermediate transfer belt 5 interposed therebetween. A sheet P as a recording material conveyed by a roller pair 13 and a roller (not shown) is sent between the intermediate transfer belt 5 and the transfer unit 7 and is formed on the image forming surface of the intermediate transfer belt 5. Is transferred by the transfer unit 7. A fixing device 8 having a pair of fixing rollers is disposed downstream of the transfer device 7 in the conveyance direction of the paper P. The paper P on which the toner image has been transferred is transferred to the paper P by the fixing device 8. After being fused and fixed, the sheet is discharged out of the image forming apparatus 100 and placed on a discharge tray (not shown).
Further, on the opposite side of the developing device 4 with the photoconductor 1 interposed therebetween, a static eliminator 9 having a function of eliminating the outer peripheral surface of the photoconductor 1 is disposed.

In the image forming apparatus 100 shown in FIG. 3, a monochrome image is formed during the rotation process in which the photoreceptor 1 rotates once. That is, the charger 2 charges the outer peripheral surface of the photosensitive member 1, the static eliminator 9 discharges the outer peripheral surface, and the exposure device 3 applies a laser beam modulated according to black image data representing a monochrome image to be formed. Scanning on the outer peripheral surface of the photosensitive member 1 is repeated while switching image data used for modulation of the laser beam every time the photosensitive member 1 rotates once. Further, the developing device 4 operates a developing device (not shown) corresponding to the outer peripheral surface of the photosensitive member 1 to develop the electrostatic latent image formed on the outer peripheral surface of the photosensitive member 1 into a black color. A black toner image having a specific color can be formed on the outer peripheral surface of the photoreceptor 1.
As a result, every time the photoconductor 1 makes one revolution, a black toner image is repeatedly formed on the outer peripheral surface of the photoconductor 1, and a monochrome image is formed.

2) Full-color image forming apparatus 200
The image forming apparatus of the present invention may be a tandem type color image forming apparatus in addition to the monochrome image forming apparatus shown in FIG. Next, a tandem color image forming apparatus will be described. The “tandem image forming apparatus” refers to an image forming apparatus having two or more of the following image forming units.

FIG. 4 is a configuration diagram of a main part of a full-color printer which is an example of an image forming apparatus according to an embodiment of the present invention.
In the image forming apparatus 200 shown in FIG. 4, the charging device 2 (ad) is a contact charging device, the transfer device has a configuration employing an intermediate transfer method, and the charging device 2 (ad). ), An exposure device 3 (ad), and a developing device 4 (ad), and a tandem image forming device having two or more image forming units.
More specifically, the tandem image forming apparatus 200 includes four photoreceptors 1 (a to d) (for example, the photoreceptor 1a is yellow, the photoreceptor 1b is magenta, and the photoreceptor 1c is cyan, in the housing 300. The photosensitive member 1d is capable of forming an image having a black color), and is arranged in parallel with each other along the intermediate transfer belt 5.

Here, each of the photoreceptors 1 (a to d) mounted on the image forming apparatus 200 has a configuration of the photoreceptor of the present invention described later.
Each of the photoreceptors 1 (a to d) can be rotated in a predetermined direction (clockwise on the paper surface), and a charging roll 2 (2a to 2d) (a contact charging device for charging the photoreceptor) along the rotation direction. ), Developing devices 4 (a to d) (developing devices for developing toner images by developing electrostatic latent images formed by exposure devices), primary transfer rolls 6 (a to d) {by developing devices A transfer device for primarily transferring the formed toner image onto an intermediate transfer belt 5 (intermediate transfer member) described later is disposed. Each of the developing devices 4 (a to d) can be supplied with toners of four colors of yellow, magenta, cyan, and black accommodated in a toner cartridge (not shown), and the primary transfer roll 6 (a -D) are in contact with the photoreceptor 1 (a-d) via the intermediate transfer belt 5 (intermediate transfer member for transferring the primary transfer image to the transfer medium P).

Further, an exposure device 3 (ad) serving as a laser light source (an exposure device that exposes an electrophotographic photosensitive member charged by a charging device to form an electrostatic latent image) is disposed at a predetermined position in the housing 300. Thus, it is possible to irradiate the surface of the charged photoreceptor 1 (a to d) with laser light emitted from a laser light source (not shown). The exposure apparatus 3 (a to d) has the same configuration as the exposure apparatus 3 described later.
Thus, the charging, exposure, development, and primary transfer processes are sequentially performed in the rotation process of the photoreceptor 1 (a to d), and the toner images of the respective colors are transferred onto the intermediate transfer belt 5 in an overlapping manner.

  As described above, the multi-beam exposure apparatus 3 (ad) that scans a plurality of laser beams on the photosensitive member to form an electrostatic latent image, and the photosensitive member 1 (ad) having the configuration described later. ) Can easily improve the image quality, increase the image forming speed, and reduce the size of the apparatus, and obtain an image with good image quality even after repeating the image forming process over a long period of time. Can do.

(2) Each component A of the image forming apparatus: exposure apparatus 3
In order to increase the resolution of the image, it is effective to reduce the particle diameter of the toner and reduce the spot diameter of the laser beam for image formation. In particular, in an ultra-high-quality machine targeted for printing pictorial images such as high-quality photographs, a resolution of 1200 dpi or more is required, and a technique for reducing the spot diameter to 30 μm or less is required. Examples of means for reducing the spot diameter of the laser beam include improving the accuracy of the optical system for irradiating the photoconductive layer with the laser beam and increasing the aperture ratio of the imaging lens. The exposure apparatus 3 preferably has a configuration employing a multi-beam method.
Next, the exposure apparatus 3 will be described. The exposure apparatus 3 preferably includes a surface emitting laser array (not shown) that emits n (n is at least 8 or more) laser beams. Note that a surface emitting laser array (not shown) formed by arraying surface emitting lasers can be configured to emit, for example, several tens of laser beams, and an array of surface emitting lasers {surface emitting lasers The arrangement of laser beams emitted from an array (not shown) can be arranged two-dimensionally (for example, in a matrix) in addition to the arrangement in one column.

As a laser array in which light emitting points that are laser beam generation sources are two-dimensionally arranged, for example, a total of nine light emitting points of 3 rows in the main scanning direction and 3 columns in the sub scanning direction are arranged at predetermined intervals. One that is dimensionally arranged. Further, the light emitting points arranged in the main scanning direction are arranged so that the distance obtained by dividing the distance from the light emitting points adjacent to each other in the sub scanning direction into four steps is one step, and is shifted step by step in the sub scanning direction. Yes. In other words, if it is limited to the sub-scanning direction, a light emitting point is arranged for each step. In this way, by arranging the light emission points in a stepwise manner in the sub-scanning direction, it is possible to scan scanning lines having different light emission points. Thereby, the laser array can simultaneously scan nine scanning lines.
Further, the light emitting points of the surface emitting laser array are preferably arranged in 3 rows or more × 3 columns or more as described above, more preferably 4 rows or more × 4 columns or more, and 6 rows or more × It is particularly preferable to arrange in 6 or more rows. As a result, there is a tendency that higher image quality (higher resolution) of the image to be formed and higher image formation speed can be realized more reliably.

Further, as described above, the exposure apparatus 3 preferably scans the photosensitive member 1 independently with eight or more laser beams, but the above effects (higher image quality and higher speed) can be obtained more effectively. From the viewpoint, the number of beams is more preferably 16 or more, and particularly preferably 32 or more.
As a result, the surface emitting laser array emits n laser beams that are turned on and off at a timing corresponding to the modulation signal and whose light amount when turned on is a light amount corresponding to the drive amount setting signal. The laser beam is scanned and exposed on the outer peripheral surface of the photosensitive member 1, whereby an electrostatic latent image is formed on the outer peripheral surface of the electrophotographic photosensitive member 1. The electrostatic latent image is developed as a toner image by the developing device 4, the toner image is transferred to the paper P through the transfer by the transfer devices 6 and 7, and melted and fixed on the paper P by the fixing device 8. An image is recorded in P.

B: Charging device 2
As the charging device 2 (charging member), a contact charging method using a charging roll, a charging brush, a charging film, a charging tube, or the like, or a non-contact method such as corotron or scorotron can be adopted. Among them, the contact charging type charging device such as the one in which the charging unit 2 has an appropriate gap with respect to the surface of the photosensitive member and is disposed in the vicinity of the photosensitive member, is a viewpoint of downsizing the image forming apparatuses 100 and 200. To preferred. In the contact charging method, the surface of the photosensitive member is charged by applying a voltage to a conductive member brought into contact with the surface of the photosensitive member. The shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, or a roller shape, but a roller-like member is particularly preferable. The roller-like member rotates at the same peripheral speed as that of the photoreceptor without contacting the photoreceptor, and functions as a charging means. However, some driving means may be attached to the roller member and rotated at a peripheral speed different from that of the photosensitive member to be charged.

The applied voltage to the contact charging member can be either direct current or alternating current. It can also be applied in the form of direct current + alternating current (a direct current voltage and an alternating current voltage superimposed).
In the present invention, since the photoreceptor 1 has excellent mechanical strength, excellent durability can be exhibited even when such a contact charging method is used.

C: Developing device 4
As the developing device 4, a conventionally known developing device using a regular developer such as a one-component system or a two-component system can be used. Among these developers, it is preferable to use a two-component development method using a two-component developer for the reason of improving the image quality. In this case, the developer used for visualizing the electrostatic latent image is composed of toner and carrier. Further, the shape of the toner to be used is not particularly limited, and for example, an irregular toner by a pulverization method or a spherical toner by a polymerization method is preferably used.

D: Transfer device 6, 7
As a transfer unit, for example, a direct transfer method in which a toner image on an electrophotographic photosensitive member is directly transferred to a transfer medium, a toner image on an electrophotographic photosensitive member is transferred to an intermediate transfer member, and further transferred to a transfer medium. An intermediate transfer method.
As the transfer devices 6 and 7, for example, contact transfer chargers using belts, rollers, films, rubber blades, scorotron transfer chargers using corona discharge, corotron transfer chargers, etc. Vessel. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the present invention, in addition to the transfer charger, a peeling charger can be used in combination.

E: Static elimination device 9
The image forming apparatus of the present invention may further include a static eliminator such as an erase light irradiation device. As a result, when the electrophotographic photosensitive member is repeatedly used, the phenomenon that the residual potential of the electrophotographic photosensitive member is brought into the next cycle is prevented, so that the image quality can be further improved.
Examples of the light neutralizing device include a tungsten lamp and an LED, and examples of the light quality used in the light neutralizing process include white light such as a tungsten lamp and red light such as LED light. The output intensity of the irradiation light in the photostatic process is set so as to be several to thirty times the amount of light indicating the half exposure sensitivity of the electrophotographic photosensitive member. In the present embodiment, light from such a light neutralizing device is taken in through an opening for static elimination exposure, and the photosensitive member is neutralized.

In this way, in the rotation process of the photoreceptor 1, image formation is repeatedly performed by sequentially performing the charging, exposure, development, transfer, and charge removal processes. Here, the photoconductor 1 is a photoconductor 1 which will be described later, and both the wear resistance and the electrical characteristics are achieved at a sufficiently high level. It is possible to obtain a good image quality without causing image quality defects such as fog. Therefore, according to the present embodiment, even when used repeatedly over a long period of time, the image forming apparatuses 100 and 200 that can sufficiently prevent the occurrence of wear on the photoreceptor and can form a color image with excellent image quality at high speed. Realized.
The present invention is not limited to the above embodiment. For example, the apparatus shown in FIG. 4 may include a process cartridge including the photoreceptor 1, the contact charging device 2, and the developing device 4. By using such a process cartridge, maintenance can be performed more easily.

(3) Process cartridge 400
Next, the process cartridge of the present invention will be described. FIG. 5 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the process cartridge of the present invention. The process cartridge 400 includes a charging device 2, a developing device 4, an intermediate transfer body 6 (intermediate transfer device), an opening 402 for exposure, and an opening 401 for static elimination exposure together with the photoreceptor 1. (Not shown) are combined and integrated. Further, the process cartridge 400 has a configuration in which the transfer method of the transfer device 7 adopts an intermediate transfer method in which the toner image is transferred to the transfer medium P via the intermediate transfer body 6. The photoreceptor 1 has a configuration of an electrophotographic photoreceptor according to the present invention described later. Further, the charging device 2, the developing device 4, and the intermediate transfer member 6 mounted on the process cartridge have the configurations of the respective elements of the present invention described above.

The process cartridge 400 is detachably attached to the image forming apparatus main body including the transfer device 7, the fixing device 8, and other components not shown. It constitutes.
Such a process cartridge of the present invention is mounted on the image forming apparatus on which the exposure apparatus having the surface emitting laser array described above is mounted. By mounting the electrophotographic photosensitive member, It is possible to achieve higher image quality, higher image formation speed, and longer life of the photoreceptor.

(4) Photoconductor 1
FIGS. 6 and 7 are schematic cross-sectional views each showing a preferred example of the photoreceptor 1, and are partial cross-sectional views when the photoreceptor 1 is cut along the stacking direction of the conductive substrate 500 and the photosensitive layer 504. . In the photoreceptor of the present invention, at least a photosensitive layer is formed on a conductive substrate, and such a photosensitive layer is formed by laminating a charge generation layer and a charge transport layer. A single layer type in which the transport material is formed in the same layer may be used.
A photoreceptor 1 shown in FIG. 6 has a structure in which an undercoat layer 501, a photosensitive layer 504, and a protective layer 505 are sequentially laminated on a conductive substrate 500.
The photoreceptor 1 shown in FIG. 7 has a structure in which an undercoat layer 501, a charge generation layer 502, a charge transport layer 503, and a protective layer 505 are sequentially laminated on a conductive substrate 1.

Hereinafter, each element constituting such a photoreceptor 1 will be described in detail.
First, the photosensitive layer will be described.
1) Charge generation layer A: charge generation material For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, An azo pigment having a diphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton, an azo pigment having a fluorenone skeleton, an azo pigment having an oxadiazole skeleton, an azo pigment having a bis-stilbene skeleton, an azo pigment having a distyryloxadiazole skeleton, Azo pigments having a distyrylcarbazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, There are anine and azomethine pigments, indigoid pigments, and bisbenzimidazole pigments, which can be used alone or in combination of two or more. Among these, azo pigments represented by the following general formula (1) (in particular, asymmetric azo pigments in which X and Y are different from each other) are preferable for adjusting the photoreceptor sensitivity to the sensitivity suitable for the present invention.

（一般式（１）中、Ｘ及びＹは、それぞれ独立に、下記一般式（２）

（一般式（２）中、Ｒ₃は、水素原子、アリール基又はアルキル基であり、Ｒ₄、Ｒ₅、Ｒ₆、Ｒ₇及びＲ₈は、それぞれ独立に、水素原子、水酸基、アルキル基、アルコキシ基、シアノ基、ジアルキルアミノ基、ニトロ基、ハロゲン基、又はハロゲン化アルキル基であり、Ｚは、置換基を有してもよい炭素環式芳香族又は置換基を有してもよい複素環式芳香族を構成するのに必要な原子団である。）
で示されるカプラー残基であり、Ｒ₁及びＲ₂は、それぞれ独立に、水素原子、アルキル基、アルコキシ基、シアノ基又はハロゲン基である。）

(In general formula (1), X and Y are each independently the following general formula (2)

(In General Formula (2), R ₃ is a hydrogen atom, an aryl group or an alkyl group, and R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a hydroxyl group, or an alkyl group. , An alkoxy group, a cyano group, a dialkylamino group, a nitro group, a halogen group, or a halogenated alkyl group, and Z may have a carbocyclic aromatic group or a substituent that may have a substituent. It is an atomic group necessary for constituting a heterocyclic aromatic.)
And R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen group. )

  In addition, in the X-ray diffraction spectrum using phthalocyanine pigments, particularly CuKα characteristic X-rays, strong diffraction at Bragg angles (2θ ± 0.2 °) of 9.4 °, 9.6 ° and 24.0 ° The diffraction peak at the position of 27.2 ° is the strongest, the diffraction peak at the position of 7.3 ° is the diffraction peak at the lowest angle, the diffraction peak at 7.3 °, the 9.4 ° A crystal of titanyl phthalocyanine that does not have a diffraction peak between 2 ° diffraction peaks and does not have a diffraction peak at a position of 26.3 ° is preferable in order to adjust the sensitivity of the photoreceptor to a sensitivity suitable for the present invention.

  Examples of a method for dispersing the charge generating material and the binder resin in a solvent include commonly used dispersing means such as a ball mill, an attritor, and a sand mill. In this case, it is preferable to carry out under the condition that the crystal form of the charge generating material is not changed by the dispersion process. The particle size of the charge generation material is preferably 0.5 μm or less, more preferably 0.3 μm or less, and most preferably 0.15 μm or less.

B: Binder resin For example, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, polyvinyl benzal Polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, and other thermoplastic or thermosetting resins In addition to molecular compounds, addition polymerization resins such as polyethylene, polypropylene, polyamide, and phenoxy resin, polyaddition resins, polycondensation resins, styrene resins There are high molecular compounds such as Kuryl copolymer, insulating copolymer resin such as vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and high molecular organic semiconductor such as poly-N-vinylcarbazole. Alternatively, two or more types can be used in combination. The amount of the binder contained in the charge generation layer is preferably 0 to 500 parts by weight, and most preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generation material.

C: Solvent For example, there are isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin. These can be used in combination. Among these, non-halogen solvents are preferable from the viewpoint of reducing environmental burden. Examples of the non-halogen solvent include cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof.

The charge generation layer can be applied by using a commonly used means such as spray coating, beam coating or dipping coating of the resin dispersion.
The charge generation layer is obtained by applying and drying a suitable solution or dispersion solution of a charge generation material, a solvent, and, if necessary, a binder resin on a conductive substrate, and the film thickness is preferably 0. 0.01 to 5 μm, optimally 0.1 to 2 μm.

2) Charge transport layer A: hole transport material (charge transport material)
For example, poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, oxadiazole derivatives, Imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives , Hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. These can be used alone or in combination of two or more.

B: Electron transport material (charge transport material)
For example, chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7- Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5 , 5-dioxide, benzoquinone derivatives and the like, and these can be used alone or in combination of two or more.
The amount of the charge transport material contained in the charge transport layer is preferably 20 to 300 parts by weight, and most preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.

C: Binder Resin Examples of the binder resin used for the charge transport layer include those described in the charge generation layer, and these can be used alone or in combination of two or more.
The charge transport layer is obtained by coating and drying a binder resin, a charge transport material, and, if necessary, a suitable solution or dispersion of the additive on the conductive substrate, and this film thickness is preferably 5-30 μm, optimally 10-25 μm.

D: Additive Low molecular compounds such as lubricants, plasticizers, antioxidants, UV absorbers and leveling agents may be added for the purpose of improving the gas barrier properties of the charge transport layer and improving the environmental resistance. Can be used alone or in combination of two or more.
In this case, the amount of the low-molecular compound added is preferably 0.1 to 50 parts by weight, and optimally 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymer compound. The amount is preferably in the range of 0.001 to 5 parts by weight with respect to 100 parts by weight of the polymer compound.

E: Solvent Examples of the solvent used in the charge transport layer include those described in the charge generation layer, and these can be used alone or in combination of two or more.
The charge transport layer can be applied by spray coating, beam coating or dipping coating of the resin dispersion.

3) Photosensitive layer When a single photosensitive layer is provided by a casting method or the like, a single-layer structure is formed using materials such as the above-described charge generation materials, charge transport materials (hole transport materials, electron transport materials), and binder resins. do it. The thickness of the single photosensitive layer is suitably about 5 to 100 μm, and preferably about 10 to 30 μm.
In the present invention, low-molecular compounds such as lubricants, plasticizers, antioxidants, ultraviolet absorbers and leveling agents may be added. In this case, the amount of the low-molecular compound added is preferably 0.1 to 50 parts by weight, and optimally 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymer compound. The amount is preferably in the range of 0.001 to 5 parts by weight with respect to 100 parts by weight of the polymer compound.

In the photoreceptor as the image carrier in the present invention, a protective layer can be provided on the surface of the photosensitive layer. As a result, the wear resistance is improved, so that fluctuations in the film thickness are suppressed and a uniform image can be obtained in the long term.
Next, the protective layer will be described.
The protective layer in this example is roughly classified into two types, a filler dispersion type and an organic cross-linking protective film.
First, the filler dispersion type will be described. This is designated as “protective layer A”.

4) Protective layer A
A: Charge transport material Examples of the charge transport material used in the protective layer include those described in the charge transport layer above, and these can be used alone or in combination of two or more. Among these, a polymer charge transport material is preferable for enhancing the mechanical durability and charge transport ability of the photoreceptor.

B: Binder resin For example, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene Terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethyl bentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, Polyvinylidene chloride, epoxy resin, or curing agents for these resins are used alone or in combination of two or more.

C: Conductive fine particles (filler)
Examples of the conductive fine particles include inorganic pigments, metals, and metal oxides. Preferably, inorganic pigment or metal oxide of silica, alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide coated titanium oxide, tin coated indium oxide, antimony coated tin oxide or zirconium oxide There are ultrafine particles. These may be used alone or in admixture of two or more.
In general, when particles are dispersed in a protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of incident light to prevent scattering of incident light by the dispersed particles, and the conductivity dispersed in the protective layer. The particle diameter of the insulating particles is preferably 0.5 μm or less.

Various additives can be added for the purpose of improving the dispersibility of the conductive fine particles, the adhesiveness with the binder resin, or the coating film smoothness after film formation. For improving the dispersibility, it is very effective to modify the surface of the conductive fine particles with a coupling agent or a leveling agent. Furthermore, it is effective to use a curable resin as the binder resin from the viewpoint of improving dispersibility.
The content in the protective layer is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, based on the total weight of the protective layer. If the amount is less than 10% by weight, the wear resistance of the photoreceptor may not be sufficiently exhibited. If the amount exceeds 40% by weight, the sensitivity of the photoreceptor tends to decrease.

  The volume average diameter of the filler is preferably 0.1 μm to 2 μm, and optimally 0.3 μm to 1 μm. If it is less than 0.1 μm, the mechanical durability is not sufficient, so that a high-quality image may not be stably realized over a long period of time. If it exceeds 2 μm, the film characteristics are deteriorated or the film formation is difficult. Tend to.

The specific resistance of the filler used in the present invention is preferably 10 ¹⁰ Ω · cm or more. Examples of such a filler include alumina, zirconia, titanium oxide, and silica. Among these, α-alumina, which has a hexagonal close-packed structure and high thermal stability and hardness characteristics, is preferable from the viewpoint of suppressing deterioration in image quality such as image blur.
The specific resistance of the filler is obtained, for example, using a measuring apparatus having the same configuration as that disclosed in Japanese Patent Laid-Open Nos. 5-94049 (FIG. 1) and 5-113688 (FIG. 1). be able to.

D: solvent For example, ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, ethers such as dioxane, tetrahydrofuran, ethyl cellosolve, aromatics such as toluene and xylene, halogens such as chlorobenzene and dichloromethane, ethyl acetate, There are esters such as butyl acetate, and these can be used alone or in combination of two or more.
Examples of a method for dispersing the filler and the binder resin in a solvent include commonly used dispersing means such as a ball mill, an attritor, and a sand mill.

E: Additive Low molecular compounds such as lubricants, plasticizers, antioxidants and ultraviolet absorbers and leveling agents may be added for the purpose of improving the gas barrier properties of the photosensitive layer and improving the environmental resistance. These can be used alone or in combination of two or more.
In this case, the amount of the low-molecular compound added is preferably 0.1 to 50 parts by weight, and optimally 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymer compound. The amount is preferably in the range of 0.001 to 5 parts by weight with respect to 100 parts by weight of the polymer compound.

F: Others The protective layer A may contain a lubricant powder. Friction between the photosensitive member and the charging member or friction between the photosensitive member and a transfer material such as a recording material is reduced, and the mechanical load on the image forming apparatus can be reduced. Further, since the releasability on the surface of the photoreceptor is improved, the adhesion of the developer can be prevented. As such a lubricant particle, it is preferable to use a fluororesin, a silicone resin, or a polyolefin resin having a low critical surface tension.
Particularly preferred is a tetrafluoropolyethylene resin. In this case, the addition amount of the lubricant powder is preferably 2 to 50% by weight, more preferably 5 to 40% by weight, based on the total weight of the protective layer. If the amount is less than 2% by weight, the amount of the lubricant powder is not sufficient, so that the effect of improving the chargeability may not be sufficiently exerted. If the amount exceeds 50% by weight, the resolution of the image or the sensitivity of the photoreceptor decreases. Tend to.

The protective layer A is obtained by applying and drying a binder resin, a charge transport material, a solvent, and, if necessary, an appropriate pulverized solution or dispersion of a filler on the photosensitive layer, and this film thickness is preferably 1-15 μm, optimally 1-9 μm. If the thickness is less than 1 μm, the durability is not sufficient, so that a high-quality image may not be stably realized over a long period of time, and if it exceeds 15 μm, the resolution tends to decrease or the sensitivity of the photoreceptor tends to decrease.
The protective layer can be applied by spray coating, beam coating or penetration (dipping) coating of the resin dispersion.

Next, the organic crosslinking protective film will be described. This is designated as “protective layer B”.
5) Protective layer B
The protective layer B is preferably a protective layer formed by curing at least a trifunctional or higher functional radical polymerizable compound having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure. .
A: Trifunctional or higher functional radical polymerizable compound having no charge transporting structure In the present invention, the radical polymerizable functional group of the trifunctional or higher functional radical polymerizable compound having no charge transporting structure is an acryloyloxy group and It is preferably a methacryloyloxy group.
A compound having 3 or more acryloyloxy groups can be obtained by, for example, using a compound having 3 or more hydroxyl groups, an acrylic acid (salt), an acrylic acid halide, or an acrylic ester to cause esterification or transesterification. It is done. A compound having three or more methacryloyloxy groups can be obtained in the same manner. In addition, the radically polymerizable functional group of the radically polymerizable radical compound having three or more functional groups having no charge transporting structure may be the same or different.

  Examples of the trifunctional or higher functional radical polymerizable compound having no charge transporting structure include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified trimethylolpropane triacrylate, and EO-modified trimethylolpropanetri. Acrylate, PO-modified trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH-modified glycerol triacrylate, EO Modified glycerol triacrylate, PO modified glycerol triacrylate, (Acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl Modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO modified phosphoric acid triacrylate, 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate, etc. . These may be used alone or in admixture of two or more.

  Further, the trifunctional or higher functional radical polymerizable compound having no charge transporting structure has a molecular weight ratio of 250 or less with respect to the number of radical polymerizable functional groups in order to form a dense crosslinked structure in the organic crosslinking protective layer. It is desirable. If it exceeds 250, the organic crosslinking protective layer tends to be softened and the abrasion resistance of the photoreceptor tends to be lowered. For this reason, among the compounds exemplified above, it is not preferable to use a compound having an extremely long modifying group alone as a compound having a modifying group such as HPA, EO, or PO.

  The addition amount of the trifunctional or higher functional radical polymerizable compound having no charge transporting structure is preferably 20 to 80% by weight, optimally 30 to 70% by weight based on the total amount of the organic crosslinking protective layer. %. If it is less than 20% by weight, the three-dimensional crosslinking density of the organic crosslinking protective layer is small, so that the wear resistance may be lowered. If it exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electric characteristics are reduced. Tends to be insufficiently deteriorated.

B: Monofunctional radically polymerizable compound having a charge transporting structure The monofunctional radically polymerizable compound having a charge transporting structure used in the present invention preferably has an acryloyloxy group or a methacryloyloxy group. Examples of the charge transporting structure include a hole transporting structure such as a triarylamine structure, a hydrazone structure, a pyrazoline structure, and a carbazole structure, or an electron having a condensed polycyclic quinone structure, a diphenoquinone structure, a cyano group, a nitro group, and the like. An electron transporting structure of an attractive aromatic ring can be mentioned, among which a triarylamine structure is preferable.

（一般式（３）及び（４）中、Ｒ₁は、水素原子、ハロゲン基、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基、置換若しくは無置換のアリール基、シアノ基、ニトロ基、アルコキシ基、一般式
−ＣＯＯＲ₂
（式中、Ｒ₂は、水素原子、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基又は置換若しくは無置換のアリール基である。）
で示される官能基、一般式
−ＣＯＹ
（式中、Ｙは、ハロゲン基である。）
で示される官能基又は一般式
−ＣＯＮＲ₃Ｒ₄
（式中、Ｒ₃及びＲ₄は、それぞれ独立に、水素原子、ハロゲン基、置換若しくは無置換のアルキル基、置換若しくは無置換のアラルキル基又は置換若しくは無置換のアリール基である。）
で示される官能基であり、
Ａｒ₁及びＡｒ₂は、それぞれ独立に、置換又は無置換のアリーレン基であり、Ａｒ₃及びＡｒ₄は、それぞれ独立に、置換又は無置換のアリール基であり、Ｘは、単結合、置換若しくは無置換のアルキレン基、置換若しくは無置換のシクロアルキレン基、置換若しくは無置換のオキシアルキレン基、酸素原子、硫黄原子又はビニレン基であり、Ｚ₁は、置換若しくは無置換のアルキレン基、置換若しくは無置換のオキシアルキレン基又は一般式
−ＣＯＯＲ₆−
（式中、Ｒ₆は、アルキレン基である。）
で示される官能基であり、ｍは、それぞれ独立に、０以上３以下の整数である。） In the present invention, the monofunctional radically polymerizable compound having a charge transporting structure is preferably one or more of the compounds represented by the following general formulas (3) and (4). Thereby, electrical characteristics such as sensitivity and residual potential can be favorably sustained.

(In the general formulas (3) and (4), R ₁ represents a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a cyano group, a nitro group, Group, alkoxy group, general formula -COOR ₂
(Wherein R ₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by the general formula -COY
(In the formula, Y is a halogen group.)
Or a functional group represented by the general formula -CONR ₃ R ₄
(Wherein R ₃ and R ₄ are each independently a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by
Ar ₁ and Ar ₂ are each independently a substituted or unsubstituted arylene group, Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group, and X is a single bond, substituted or An unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted oxyalkylene group, an oxygen atom, a sulfur atom or a vinylene group, and Z ₁ is a substituted or unsubstituted alkylene group, substituted or unsubstituted Substituted oxyalkylene group or general formula —COOR ₆ —
(In the formula, R ₆ is an alkylene group.)
And m is independently an integer of 0 or more and 3 or less. )

Below, the specific example of the substituent in the compound shown by General formula (3) and (4) is shown.
In R ₁ , the alkyl group is methyl, ethyl, propyl, butyl, aryl is phenyl, naphthyl, aralkyl is benzyl, phenethyl, naphthylmethyl, alkoxy Examples of the group include a methoxy group, an ethoxy group, and a propoxy group. These include an alkyl group such as a halogen group, a nitro group, a cyano group, a methyl group, and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and a phenoxy group. Or an aryl group such as a phenyl group or a naphthyl group, or an aralkyl group such as a benzyl group or a phenethyl group. Of these, a hydrogen atom or a methyl group is preferable.

In the present invention, the aryl group of Ar ₃ and Ar ₄ includes a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring. For example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group, s -Indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aseantrilenyl group, triphenylyl group, pyrenyl group, chrysenyl group Group, naphthacenyl group and the like.

Non-condensed cyclic hydrocarbon group includes monovalent hydrocarbon compound such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether, diphenyl sulfone, biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, triphenyl. Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as phenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane and polyphenylalkene, or ring-assembled hydrocarbon compounds such as 9,9-diphenylfluorene Of these monovalent groups.
Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

The substituted or unsubstituted aryl group of Ar ₃ and Ar ₄ may have a substituent as shown below.
(1) Halogen group, cyano group, nitro group, etc. (2) Alkyl group C ₁ -C ₁₂ , preferably C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl group , still, fluoro group, a hydroxyl group, a cyano group, C ₁ -C ₄ alkoxy group, a phenyl group or a halogen group, phenyl substituted with an alkyl group or a C ₁ -C ₄ alkoxy group C ₁ -C ₄ It may have a group. Specifically, methyl group, ethyl group, n-butyl group, isopropyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl group 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group.

(3) Alkoxy group (-OR)
(In the formula, R is an alkyl group defined in (2).)
Specifically, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, t-butoxy group, n-butoxy group, s-butoxy group, isobutoxy group, 2-hydroxyethoxy group, benzyloxy group, trifluoro A methoxy group etc. are mentioned.
(4) The aryloxy group an aryl group, a phenyl group, a naphthyl group, an alkoxy group of C ₁ -C _4, which may have an alkyl group or a halogen group C ₁ -C _4. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.

(5) Alkyl mercapto group or aryl mercapto group Specific examples include a methylthio group, an ethylthio group, a phenylthio group, and a p-methylphenylthio group.
(6) Amino group (—NR ₁ R ₂ )
(In the formula, R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group or an aryl group defined in (2). Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. , C ₁ -C ₄ alkoxy group, C ₁ -C ₄ alkyl group or halogen group, and R ₁ and R ₂ may form a ring together.)
Specific examples include amino group, diethylamino group, N-methyl-N-phenylamino group, diphenylamino group, ditolylamino group, dibenzylamino group, piperidino group, morpholino group, and pyrrolidino group.

(7) Alkylenedioxy group or alkylenedithio group Specific examples include a methylenedioxy group and a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

Examples of the arylene group of Ar ₁ and Ar ₂ include a divalent group derived from the aryl group of Ar ₃ and Ar ₄ .
The alkylene group for X is a C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , more preferably a C _{1 to} C ₄ linear or branched alkylene group, and further includes a fluoro group, a hydroxyl group, and a cyano group. group, C ₁ -C ₄ alkoxy group, which may have a phenyl group or a halogen group, C ₁ -C ₄ alkyl or C ₁ -C ₄ phenyl group substituted with an alkoxy group. Specifically, methylene group, ethylene group, n-butylene group, isopropylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene. Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group.

Cycloalkylene group X represents a cyclic alkylene group of C ₅ -C _7, a fluoro group, a hydroxyl group, which may have an alkyl group or an alkoxy group of C ₁ -C ₄ a C ₁ -C _4. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
The oxyalkylene group of X is derived from, for example, an oxyalkylene group such as a tyleneoxy group or a propyleneoxy group, an alkylenedioxy group derived from ethylene glycol, propylene glycol, or the like, diethylene glycol, tetraethylene glycol, tripropylene glycol, or the like. Di (oxyalkylene) oxy group or poly (oxyalkylene) oxy group. The alkylene group of the oxyalkylene group may have a hydroxyl group, a methyl group, an ethyl group, or the like.

（式中、Ｒ₅は、水素原子、アルキル基（（２）で定義されるアルキル基と同じ）又はアリール基（Ａｒ₃及びＡｒ₄のアリール基と同じ）であり、ａは、１又は２であり、ｂは、１〜３の整数である。）
で示される置換基が挙げられる。 As the vinylene group of X, the general formula

Wherein R ₅ is a hydrogen atom, an alkyl group (same as the alkyl group defined in (2)) or an aryl group (same as the aryl group of Ar ₃ and Ar ₄ ), and a is 1 or 2 And b is an integer of 1 to 3.)
The substituent shown by these is mentioned.

As the alkylene group and oxyalkylene group for Z ₁ , the same as those for X can be mentioned. In addition, the general formula of —Z ₁ —COOR ₆ —
(In the formula, R ₆ is an alkylene group.)
Examples of the functional group represented by are caprolactone-modified groups.

（一般式（５）中、ｏ、ｐ及びｑは、それぞれ独立に、０又は１であり、Ｒ₂は、水素原子又はメチル基であり、Ｒ₃及びＲ₄は、それぞれ独立に、炭素数が１以上６以下のアルキル基であり、ｓ及びｔは、それぞれ独立に、０以上３以下の整数であり、Ｚ₂は、単結合、メチレン基、エチレン基又は構造式

で示される官能基である。）
なお、ｓ又はｔが２又は３である場合は、複数のＲ₃又はＲ₄は、異なってもよい。一般式（５）で表わされる化合物の中でも、Ｒ₃及びＲ₄が、それぞれ独立に、メチル基又はエチル基である化合物が特に好ましい。 In the present invention, the monofunctional radically polymerizable compound having a charge transporting structure is more preferably a compound represented by the following general formula (5).

(In the general formula (5), o, p and q are each independently 0 or 1, R ₂ is a hydrogen atom or a methyl group, and R ₃ and R ₄ are each independently a carbon number. Is an alkyl group of 1 to 6 and s and t are each independently an integer of 0 to 3, Z ₂ is a single bond, a methylene group, an ethylene group or a structural formula

It is a functional group shown by. )
In the case s or t is 2 or 3, a plurality of R ₃ or R ₄ may be different. Among the compounds represented by the general formula (5), a compound in which R ₃ and R ₄ are each independently a methyl group or an ethyl group is particularly preferable.

  In the present invention, the compounds represented by the general formulas (3) and (4), in particular (5), are copolymerized with a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure, thereby forming a cured resin. Incorporated into the main chain, it is also incorporated into the cross-linked chain between the main chain and the main chain. In addition, in cross-linking, an intermolecular cross-link formed between one polymer and another polymer, and a site with a main chain folded in one polymer and another site are cross-linked. And intramolecular crosslinking. At this time, even if a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure is present in the main chain or in the crosslinked chain, it hangs from the chain portion. The triarylamine structure is bulky. However, the triarylamine structure is not directly bonded to the chain part, but is suspended from the chain part via a carbonyl group, etc., so it is fixed in a state where there is flexibility in steric positioning, and it is cured. It is possible to have a spatial arrangement that is reasonably adjacent to each other in the resin. For this reason, it is presumed that an intramolecular structure that is relatively free from disruption of the charge transport path can be adopted in the cross-linked charge transport layer with little structural distortion in the molecule.

Specific examples of the monofunctional radically polymerizable monomer having a charge transporting structure used in the present invention are shown below, but are not limited to these compounds.

  In the present invention, the monofunctional radically polymerizable compound having a charge transporting structure is important for imparting charge transportability to the organic cross-linking protective layer, and the content in the organic cross-linking protective layer is preferably 20 ~ 80 wt%, optimally 30-70 wt%. If it is less than 20% by weight, the charge transporting property of the organic cross-linking protective layer is not sufficient, so that the electrical properties such as a decrease in sensitivity or an increase in residual potential may be deteriorated. Along with the content of a tri- or higher functional radical polymerizable compound that does not contain bismuth, the crosslinking density tends to decrease and the wear resistance tends to be insufficient.

C: Polymerization initiator In the present invention, when an organic cross-linking protective layer is formed, a polymerization initiator may be added as necessary in order to efficiently advance the curing reaction.
Examples of the polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (Peroxybenzoyl) peroxide initiators such as hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, azobisisobutylnitrile, azobiscyclohexanecarbox Examples thereof include azo initiators such as nitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, and 4,4′-azobis-4-cyanovaleric acid.

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl (2-hydroxy -2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl- Acetophenone-based or ketal-based photopolymerization initiators such as 2-morpholino (4-methylthiophenyl) propan-1-one and 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzoin, benzoin Methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1,4 -Benzophenone photopolymerization initiators such as benzoylbenzene, thioxanthone photopolymerization initiators such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Is mentioned. Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compound, imidazole compound It is done. A compound having an effect of promoting the photopolymerization reaction can be used alone or in combination with a photopolymerization initiator. Examples of such compounds include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone. Is mentioned. These may be used alone or in admixture of two or more.
The addition amount of the polymerization initiator is preferably 0.5 to 40 parts by weight, and most preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total weight of the compound having radical polymerizability.

D: Solvent For example, alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane and propyl ether And halogen series such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatic series such as benzene, toluene and xylene, and cellosolv series such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These may be used alone or in admixture of two or more.

  The protective layer can be applied by spray coating, beam coating or dipping coating of the resin dispersion. Of these, the spray coating method is preferable from the viewpoint that the amount of residual solvent in the film can be appropriately adjusted.

In the present invention, after applying such an organic crosslinking protective layer coating solution, it is cured by external energy to form an organic crosslinking protective layer. Examples of external energy used at this time include heat, light, Radiation. As a method for applying thermal energy, heating is performed from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. As heating temperature, it is preferable that it is the range of 100 to 170 degreeC. If it is less than 100 ° C., the reaction rate is low, and thus the curing reaction tends not to be completed completely. When the temperature exceeds 170 ° C., the curing reaction proceeds non-uniformly at a high temperature, so that there is a tendency that large strains, a large number of unreacted residues, and reaction termination terminals are generated in the organic crosslinking protective layer. In order to proceed the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and further heating to 100 ° C. or higher. As light energy, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in the ultraviolet region, can be used. Select a visible light source according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is also possible. The amount of irradiation light is preferably in the range of 50 m to 1000 mW / cm ² . If it is less than 50 mW / cm ² , the curing reaction takes time. If it exceeds 1000 mW / cm ² , the progress of the reaction becomes non-uniform, so that there is a tendency for local wrinkles, many unreacted residues, and reaction termination ends to occur on the surface of the organic crosslinked protective layer. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include electron beams. Among these external energies, heat and light energies are preferable from the viewpoint of ease of reaction rate control and simplicity of the apparatus.

  The film thickness of the organic crosslinking protective layer is preferably 1 to 10 μm, and optimally 2 to 8 μm. If the thickness is less than 1 μm, the durability may fluctuate due to uneven film thickness. If the thickness exceeds 10 μm, the total thickness of the charge transport layer and the organic cross-linking protective layer increases. It tends to decrease.

5) Conductive substrate As the conductive substrate, for example, a metal such as aluminum or stainless steel; a plastic having a coating layer of an aluminum alloy or an indium oxide-tin oxide alloy; paper or plastic impregnated with conductive particles; a conductive polymer And a cylindrical cylinder and a film.

6) Undercoat layer On these conductive substrates, the adhesion of the photosensitive layer is improved, the coatability is improved, the substrate is protected, the defects are coated on the substrate, the charge injection from the substrate is improved, and the photosensitive layer is electrically destroyed. An undercoat layer may be provided for the purpose of protection against the above.
A: Resin Examples of the resin having high resistance to the general organic solvent include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, and alcohol-soluble such as copolymer nylon and methoxymethylated nylon. There are curable resins that form a three-dimensional network structure such as resin, polyurethane, melamine resin, alkyd-melamine resin, and epoxy resin, and these can be used alone or in combination of two or more.

B: Metal fine powder For example, there are fine powders of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide and indium oxide, metal sulfides and metal nitrides, and these are used alone or in combination of two or more. Can be used.

This film thickness is preferably 0.1 to 10 μm, and optimally 0.1 to 5 μm.
These undercoat layers can be formed using an appropriate solvent and coating method, as in the case of the above-described photosensitive layer.

  Further, as the undercoat layer, a metal oxide layer formed by using, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful. In addition to this, alumina is provided by anodic oxidation, organic materials such as polyparaxylylene (parylene), and inorganic materials such as silicon oxide, tin oxide, titanium oxide, ITO, ceria are provided by the vacuum thin film manufacturing method. It can be used well as an undercoat layer.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all.
(1) Example of dispersion preparation
[Preparation of pigment dispersion 1]
(Binder resin) Polyvinyl butyral resin (XYHL, manufactured by UCC) 0.25 parts by mass (solvent) Cyclohexanone 200 parts by mass (solvent) 2-butanone 80 parts by mass The above materials mixed in advance in a ball mill disperser, and A charge generating material of 2.5 parts by mass and a PSZ ball having a diameter of 10 mm were charged and dispersed at 85 rpm for 7 days. This is designated as “Pigment Dispersion Liquid 1”.
(Charge generating material) Azo compound of the following structural formula (7)

[Preparation of pigment dispersion 2]
(Charge generating material) Titanylphthalocyanine having XD spectrum (FIG. 8) 8 parts by mass (binder resin) Polyvinyl butyral resin (XYHL, manufactured by UCC) 5 parts by mass (solvent) 2-butanone 400 parts by mass Dissolved and dispersed. This is designated as “pigment dispersion 2”.

Hereinafter, specific methods for producing the photoreceptor and toner will be described.
(2) Photoconductor production example [Preparation of undercoat layer coating solution]
(Binder resin) Alkyd resin 3 parts by mass
(Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
(Binder resin) Melamine resin 2 parts by mass
(Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
(Filler) Titanium oxide 20 parts by mass
(Taipeke CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
(Solvent) 100 parts by mass of 2-butanone was dispersed and mixed to prepare an undercoat layer coating solution.

[Preparation of coating solution for charge generation layer]
Pigment dispersion liquid 1 or 2 was used as the charge generation layer coating liquid.

（結着樹脂） ポリカーボネート樹脂（ビスフェノールＺ型） １０質量部
｛パンライトＴＳ−２０５０（帝人化成社製）、粘度平均分子量５万｝
（レベリング剤） 反応性シリコーンオイル（１質量％のテトラヒドロフラン溶液）
０．２質量部
（ＫＦ５０−１００ＣＳ、信越化学工業社製）
（溶媒） テトラヒドロフラン ８０質量部
を分散混合し、電荷輸送層塗布液を調製した。 [Preparation of charge transport layer coating solution]
(Charge transport material) 7 parts by mass of a triphenylamine compound of the following structural formula (8)

(Binder resin) Polycarbonate resin (bisphenol Z type) 10 parts by mass
{Panlite TS-2050 (manufactured by Teijin Chemicals Ltd.), viscosity average molecular weight 50,000}
(Leveling agent) Reactive silicone oil (1% by weight tetrahydrofuran solution)
0.2 parts by mass
(KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)
(Solvent) 80 parts by mass of tetrahydrofuran was dispersed and mixed to prepare a charge transport layer coating solution.

[Preparation of filler dispersion type protective layer coating solution]
(Charge transport material) 3 parts by mass of triphenylamine compound of the above structural formula (8) (binder resin) 4 parts by mass of polycarbonate resin (bisphenol Z type)
{Panlite TS-2050 (manufactured by Teijin Chemicals Ltd.), viscosity average molecular weight 50,000}
(Filler) 0.7 parts by mass of aluminum oxide
{Sumicorundum AA-03 (manufactured by Sumitomo Chemical Co., Ltd.), average primary particle size 0.3
μm, refractive index 1.7, specific resistance 10 ¹⁰ Ω · cm or more}
(Solvent) 280 parts by mass of tetrahydrofuran (solvent) 80 parts by mass of cyclohexanone was dispersed and mixed to prepare a filler-dispersed protective layer coating solution. This is designated as “protective layer coating solution 1”.

[Preparation of organic crosslinking protective layer coating solution]
5 parts by mass of a tri- or higher functional radical polymerizable compound having no charge transporting structure {trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku Co., Ltd.) Molecular weight 296,
Functional group number 3, molecular weight / functional group number = 99}
Trifunctional or higher functional radical polymerizable compound having no charge transport structure 5 parts by weight {Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, Nippon Kayaku Co., Ltd.), molecular weight 1947,
Functional group number 6, molecular weight / functional group number = 325}
Monofunctional radically polymerizable compound having a charge transporting structure 10 parts by weight (Exemplary Compound No. 54)
1 part by weight of photopolymerization initiator {1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 184, manufactured by Ciba Specialty Chemicals)}
Reactive silicone compound 0.02 parts by weight (BYK-UV3570, manufactured by Big Chemie Japan)
120 parts by weight of tetrahydrofuran was dispersed and mixed to prepare an organic crosslinking protective layer coating solution. This is designated as “protective layer coating solution 2”.

[Photoconductor Production Example 1]
An aluminum cylinder having a diameter of 30 mm and a length of 340 mm was used as a base. The following first to third layers were sequentially dip coated on this substrate, and the fourth layer was laminated by spray coating to produce photoreceptor 1.
First layer (undercoat layer): produced using the coating solution obtained in the preparation of the undercoat layer coating solution.
Film thickness 3.5 μm.
Second layer (charge generation layer): Prepared using the pigment dispersion 1. Film thickness 0.2 μm.
Third layer (charge transport layer): produced using the coating solution obtained by preparing the charge transport layer coating solution.
did. Film thickness 22 μm.
Fourth layer (protective layer): Prepared using the protective layer coating solution 1 described above. Film thickness 5 μm.

[Spray application conditions]
Spray gun opening: 3/8
Coating liquid discharge pressure: 2.0 kgf / cm ²
Coating object rotation speed: 120rpm
Application speed: 7.14 mm / s
Distance between spray gun head and coated object: 50 mm
Number of applications: 2 times

[Photoconductor Production Example 2]
Photoreceptor 2 was produced in the same manner as [Photoreceptor Production Example 1] except that pigment dispersion 2 was used as the charge generation layer coating solution.

[Photoconductor Production Example 3]
Same as [Photoconductor Production Example 2], except that the protective layer coating solution 2 is used as the prescription of the protective layer coating solution, and the coating and curing conditions of the protective layer coating solution 2 are changed as shown below. Thus, a photoreceptor 3 was produced. The film thickness of the obtained protective layer is 5 μm.
[Spray application conditions]
Spray gun opening: 3.7 / 8
Coating liquid discharge pressure: 3.0 kgf / cm ²
Rotation speed of workpiece: 168rpm
Application speed: 10.7 mm / s
Distance between spray gun head and coated object: 50 mm
Number of coatings: Once [UV curing conditions]
Light source: Metal halide lamp Light source power: 160W / cm 100%
Distance between light source and object to be coated: 110 mm
Rotation speed of workpiece: 25rpm
Irradiation time: 240s
Object temperature control: 30 ° C

[Photoconductor Production Example 4]
Photoreceptor 4 was produced in the same manner as [Photoreceptor Production Example 3] except that Pigment Dispersion Liquid 1 was used as the charge generation layer coating solution.

(3) Example of pulverized toner production
[Production of polyester resin]
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane
4.0 mol polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane
1.0 mol terephthalic acid 4.5 mol trimellitic anhydride 0.5 mol dibutyltin oxide 4 g
The above formulation was reacted at 230 ° C., 8.3 kPa, in a nitrogen atmosphere for 8 hours to obtain a polyester resin having a softening point of 120 ° C.

[Manufacture of toner]
(Binder resin) 100 parts by mass of the polyester resin (colorant) Carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) 5 parts by mass (charge control agent) Styrene acrylic polymer (FCA-201-PS, manufactured by Fujikura Kasei Co., Ltd.)
4 parts by mass (release agent) Wax (Yumex 110TS, manufactured by Sanyo Kasei Kogyo Co., Ltd.) 4 parts by mass The above materials were mixed in advance and melt kneaded with a twin screw extruder. The melt-kneaded product was crushed to obtain a toner crushed product. Further, the coarsely pulverized product was finely pulverized by a collision type airflow pulverizer and then classified by wind to obtain black toner particles having an average diameter of about 9 μm. To 100 parts by mass of the obtained black toner particles, 1.05 parts by mass of silica fine particles (RA200HS, manufactured by Nippon Aerosil Co., Ltd.) was externally added to obtain a toner.

[Production of positively charged two-component developer]
The developer was obtained by mixing 5 parts by mass of the toner with 100 parts by mass of a development carrier obtained by coating a ferrite having a volume average diameter of 40 μm with a silicone resin. This is designated as “Developer 1”.

(4) Production Example of Polymerized Toner [Production Example 1 of Polymerized Toner]
[Preparation of resin particle dispersion for outer layer]
Styrene 70.1 parts by mass n-butyl acrylate 19.9 parts by mass Methacrylic acid 10.9 parts by mass The above formulation was uniformly dissolved and dispersed. This is designated as “polymerizable monomer solution 1”. Next, 3010 g of ion-exchanged water in a 5000 mL separable flask equipped with a stirrer, a nitrogen introduction tube, a temperature sensor, and a cooling tube was added to non-ionic surfactant (Naroacty N200, manufactured by Sanyo Chemical Industries) 7.08 g. Was added, and the temperature was raised to 80 ° C. while stirring under a nitrogen stream to prepare a surfactant solution. A polymerization initiator solution in which 9.2 g of a polymerization initiator (potassium persulfate KPS) is dissolved in 200 g of ion-exchanged water is added to this surfactant solution, heated to 75 ° C., and then the polymerizable monomer solution. 1 was added dropwise over 1 hour, and after completion of the addition, the system was heated and stirred at 75 ° C. for 2 hours to perform polymerization (first stage polymerization) to prepare resin particles. This is designated as “resin particle 1”.

これを「重合性単量体溶液２」とする。 Styrene 122.9 parts by mass n-Butyl acrylate 49.7 parts by mass Methacrylic acid 16.3 parts by mass Was heated to 80 ° C., uniformly dissolved and dispersed.

This is designated as “polymerizable monomer solution 2”.

  Next, 5.7 g of a nonionic surfactant (Naroacty N200, manufactured by Sanyo Chemical Industries) is dissolved in 1340 g of ion-exchanged water in a separable flask for 5000 mL equipped with a stirrer, a temperature sensor, and a cooling tube, A surfactant solution was prepared. After heating this surfactant solution to 80 ° C., the polymerizable monomer solution 2 was added for 2 hours using a mechanical disperser {CLEARMIX, manufactured by M Technique Co., Ltd.} having a circulation path. Dispersion mixing was performed to prepare a dispersion (emulsion) containing emulsified particles (oil droplets) having a dispersed particle diameter of 646 nm. Next, a polymerization initiator solution obtained by dissolving 6.51 g of a polymerization initiator (potassium persulfate KPS) in 1460 mL of ion-exchanged water and 254 mL of ion-exchanged water in this dispersion (emulsion), and n-octyl-3-mercaptopropion 0.75 g of acid ester was added to resin particle 1, and this system was heated and stirred at 80 ° C. for 3 hours to perform polymerization (second stage polymerization) to prepare resin particles using resin particle 1 as a raw material. . This is designated as “resin particle 2”.

ｎ−オクチルメルカプタン ６．４質量部
前記樹脂粒子２に、イオン交換水３４６ｍＬに重合開始剤（ＶＡ−０５７、和光純薬工業社製）８．８７ｇを溶解させた重合開始剤溶液を添加し、さらに上記処方を９５℃で１時間かけて滴下した。滴下終了後、２時間加熱、攪拌することにより重合（第３段重合）を行ったのち、２８℃に冷却、樹脂粒子２を原料とした樹脂粒子の分散液を得た。これを、「外層用樹脂粒子分散液Ａ」とする。 Styrene 322.3 parts by mass n-butyl acrylate 121.9 parts by mass Methacrylic acid 35.5 parts by mass The following aminoacrylic (meth) acrylamide compound (10) 4.5 parts by mass

6.4 parts by mass of n-octyl mercaptan To the resin particles 2, a polymerization initiator solution in which 8.87 g of a polymerization initiator (VA-057, manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 346 mL of ion-exchanged water, Furthermore, the said formulation was dripped at 95 degreeC over 1 hour. After completion of the dropping, the mixture was heated and stirred for 2 hours for polymerization (third stage polymerization), then cooled to 28 ° C., and a resin particle dispersion using resin particles 2 as a raw material was obtained. This is designated as “outer layer resin particle dispersion A”.

[Preparation of resin particle dispersion for internal particles]
Styrene 172.9 parts by mass n-butyl acrylate 55.0 parts by mass Methacrylic acid 23.1 parts by mass In the above-mentioned material in the flask equipped with a stirrer, a release agent {ester compound (8)} 96.0 parts by mass Was heated to 80 ° C., uniformly dissolved and dispersed. This is designated as “polymerizable monomer solution 3”. Next, 2.5 g of the following anionic surfactant (11) was dissolved in 1340 g of ion-exchanged water in a separable flask for 5000 mL equipped with a stirrer, a temperature sensor, and a cooling tube to prepare a surfactant solution. .

  After heating the surfactant solution to 80 ° C., the polymerizable monomer solution 3 is added for 2 hours using a mechanical disperser {CLEARMIX, manufactured by M Technique Co., Ltd.} having a circulation path. Dispersion mixing was performed to prepare a dispersion (emulsion) containing emulsified particles (oil droplets) having a dispersed particle diameter of 482 nm. Next, after adding 1460 mL of ion-exchanged water, a polymerization initiator solution in which 7.5 g of a polymerization initiator (potassium persulfate KPS) was dissolved in 142 mL of ion-exchanged water and 6.74 g of n-octanethiol were added. Polymerization (first stage polymerization) was carried out by heating and stirring the system at 80 ° C. for 3 hours to prepare resin particles. This is designated as “resin particle 3”.

Styrene 291.2 parts by weight n-butyl acrylate 132.2 parts by weight Methacrylic acid 42.9 parts by weight n-octanethiol 7.51 parts by weight Into the resin particles 2, ion exchange water 220 mL, a polymerization initiator (potassium persulfate KPS) ) A polymerization initiator solution in which 11.6 g was dissolved was added, and the above formulation was further added dropwise at 80 ° C. over 1 hour. After completion of the dropwise addition, polymerization (second-stage polymerization) is performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and using resin particles 3 as raw materials (hereinafter referred to as “resin particles 4”). ) Dispersion was obtained.

[Preparation of colorant dispersion]
After dissolving 59.0 g of the anionic surfactant (11) in 1600 mL of ion-exchanged water, the yellow pigment C.I. I. Pigment Yellow 74, 280.0 g was gradually added, and further, dispersion treatment was performed using CLEARMIX (M Technique Co., Ltd.) to prepare a colorant dispersion. This is designated as “colorant dispersion B”.
In a four-necked flask equipped with a stirrer, a nitrogen introducing tube, a temperature sensor, and a cooling tube, resin particles 4, 259.3 g (in terms of solid content), ion-exchanged water 1120 g, and the above colorant dispersion B 237 g Were added and stirred. After further heating to 30 ° C., 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 10. After that, while stirring at 30 ° C., 55.3 g of magnesium chloride hexahydrate was added to 55.3 mL of ion-exchanged water over 10 minutes. After leaving still for 3 minutes, salting out and fusion | melting of the resin particle 4 and a coloring agent were finally performed at 90 degreeC, heating up this system gradually over 60 minutes. While continuing heating and stirring, the particle size of the internal particles was measured with a Coulter Counter TA-II (manufactured by Beckman Coulter). When the volume average particle size became 5.5 μm, sodium chloride was added to 100 mL of ion-exchanged water. An aqueous solution in which 15.3 g was dissolved was added to stop the growth of the particles, and a colored particle dispersion serving as internal particles was obtained. This is designated as “colored particle dispersion C”.
The resin particle dispersion A, 87.5 g (in terms of solid content), was adjusted to pH 8 by adding a 5 mol / L sodium hydroxide aqueous solution.

  On the other hand, the colored particle dispersion C to be the internal particles is heated and stirred for about 1 hour or more to control the shape, and when the circularity becomes 0.944, the resin particle dispersion A is added to the internal particles. The outer layer resin particles were fused on the surface to form an outer layer. Next, an aqueous solution in which 123.9 g of sodium chloride was dissolved in 500 g of ion-exchanged water was added and stirred at 95 ° C. for 2 hours. Further, while gradually cooling at 8 ° C./minute, hydrochloric acid was added to adjust to pH 2 at 30 ° C., and stirring was stopped. This is a dispersion of toner particles. The average value of the circularity of the toner particles was 0.964.

[Solid-liquid separation, washing process]
The toner particle dispersion was subjected to a centrifugal dehydrator, and then washed with ion-exchanged water having a mass 20 times the solid content to obtain a toner cake.
[Drying process]
The toner cake obtained by washing was dried with a vacuum dryer until the water content reached 4% by mass to obtain toner particles.
[External additive mixing process]
0.8 parts by mass of hydrophobic silica (R805, manufactured by Nippon Aerosil Co., Ltd.) is added to the toner particles, and the peripheral speed of the rotary blade of a Henschel mixer (produced by Mitsui Miike Chemical Co., Ltd.) is set to 30 m / second and mixed for 25 minutes. did. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner. This is designated as “polymerized toner 1”.
[Production of positively charged two-component developer]
A developer was obtained by mixing 1 and 6 parts by mass of the above polymerized toner with 100 parts by mass of a development carrier obtained by coating a ferrite having a volume average diameter of 40 μm with a silicone resin. This is designated as “Developer 2”.

(5) Examples and Comparative Examples Hereinafter, the effects of the present invention will be shown by Examples and Comparative Examples.
[Example 1]
A 1200 dpi laser beam printer was prepared as a regular development method and cleanerless examination machine shown in FIG. 3, and the process time (T _ed ) was modified to 65 ms. That is, the exposure apparatus was provided with a surface emitting laser array (light emitting points arranged in two dimensions of 3 × 3 and the number of laser beams was eight), and the number of scanning lines was modified to 1200 dpi.
The cleaning rubber blade in the process cartridge was removed, and the charging method of the apparatus was contact charging in which a rubber roller was in contact.
Here, “Developer 1” made of pulverized toner was used as the developer, and “Photoreceptor 1” having a filler-dispersed protective layer was used as the photoreceptor.
The image forming apparatus was remodeled and the process conditions were set to suit these process cartridge modifications. The photosensitive member charging potential was set to -800 V in the dark portion potential.

  Next, evaluation is performed due to image density, transferability, charging roller contamination and ghosting, and charging failure after 10k (= 10000) continuous image output durability of a character document with a printing area ratio of 6% by A4 horizontal feed from the beginning. I went about image fogging.

1) Photoconductor transit time Using the photoconductor produced above, the transit time of the photoconductor was measured by the measuring method described in this specification. That is, a light attenuation curve was obtained by multi-point measurement of process time using the photoconductor characteristic evaluation apparatus described in Japanese Patent Application Laid-Open No. 2000-275872. Next, in the obtained light attenuation curve, an exposure amount that does not cause a sharp light attenuation of the photoreceptor surface potential is determined. Further, the exposure portion potential was plotted against the process time for this exposure amount, and the time (photoconductor transit time) at which the exposure portion potential started rising on the short time side of the process time was obtained.

Measurement conditions were as follows.
Line speed (mm / s) 270
Write light wavelength (nm) 655
Sub-scanning direction resolution (dpi) 1200
Static elimination voltage 8 (V)
Photoconductor charging potential -800 (V)

The process time (T _ed ) was adjusted by changing the installation angle of the surface potential probe corresponding to the developing unit with respect to the exposure station.
In addition, the process time (the time required for an arbitrary position on the photoreceptor to move from a position facing the electrostatic latent image forming unit to a position facing the developing unit) was measured by the measuring method described in the specification of the present application. That is, if the circumferential length of the photosensitive drum is L [mm], the photosensitive member line speed is v [mm / s], and the angle between the exposure position and the development position when viewed from the photosensitive member center is θ [°]. The required process time T _ed [s] is
T _ed = L / v × [θ / 360]
It becomes.
The results based on the evaluation method are summarized in Table 1.

2) Image density A square solid black image having a side of 5 mm was formed, and the image density of the solid black image was measured using an image density measuring machine RD918 manufactured by Macbeth. Evaluation was performed based on the following evaluation criteria.
A: Very good (1.3 or higher)
B: Good (1.2 or more and less than 1.3)
C: Normal (1.1 or more and less than 1.2)
D: Bad (less than 1.1)

3) Image Dirt Image dirt was visually observed after fixing and evaluated based on the following evaluation criteria.
A: Not generated B: Generated slightly C: Generated to some extent D: Generated remarkably worse

In addition, the transferability, fog, resolution, and charging roller contamination were evaluated.
4) Transferability As for transferability, the toner remaining on the photoconductor during solid black image formation is taped off with Mylar tape, and the Mylar tape is applied to the paper based on the Macbeth density of the stripped Mylar tape. Evaluation was made by subtracting the Macbeth concentration of the pasted material. Therefore, the smaller the numerical value, the better the transferability.
A: Very good (less than 0.05)
B: Good (0.05 or more and less than 0.07)
C: Normal (0.07 or more and less than 0.1)
D: Bad (over 0.1)

5) Fogging Fogging was performed by taping off the residual toner on the photoconductor when a solid white image was formed using Mylar tape, and only the Mylar tape was pasted on the paper from the Macbeth density of the stripped Mylar tape on the paper. The value was calculated by subtracting the Macbeth concentration. Therefore, the smaller the value, the better the fog suppression.
A: Very good (less than 0.05)
B: Good (0.05 or more and less than 0.07)
C: Normal (0.07 or more and less than 0.1)
D: Bad (over 0.1)

6) Resolution The resolving power was evaluated based on the reproducibility of 1200 dpi 21 μm small-diameter isolated dots that are difficult to reproduce due to the electric field being easily closed by the latent image electric field.
A: 5 or less defects in 100 B: 6 to 10 defects in 100 C: 11 to 20 defects in 100 D: 20 or more defects in 100

7) Contamination amount of charging roller The contamination of the charging roller was evaluated based on the following evaluation criteria by measuring the toner weight (mg / cm ² ) per unit area on the charging roller.
A: Not generated (less than 0.1 mg / cm ² )
B: Slightly generated (0.1 mg / cm ² or more and less than 0.3 mg / cm ² )
C: occurrence to some extent (0.3 mg / cm ² or more and less than 0.5 mg / cm ² )
D: The occurrence is extremely bad (0.5 mg / cm ² or more)

Further, the matching with respect to each of the developing roller, the photosensitive drum, and the fixing device was evaluated as follows.
8) Matching with developing roller After completion of the printout test, the appearance of residual toner adhering to the surface of the developing roller and the effect on the printout image were visually evaluated.
A: Very good (not generated)
B: Good (almost no occurrence)
C: Normal (there is sticking, but there is little influence on the image)
D: Poor (much sticking and causes image unevenness)

9) Matching with photoconductor drum After the completion of the printout test, the occurrence of scratches on the surface of the photoconductor drum and sticking of residual toner and the influence on the printout image were visually evaluated.
A: Very good (not generated)
B: Good (slight scratches are seen but there is no effect on the image)
C: Normal (there is sticking or scratching, but there is little effect on the image)
D: Poor (there is much sticking and causes vertical stripe-like image defects)

10) Matching with fixing device After completion of the printout test, scratches on the surface of the fixing roller and adhesion of residual toner were visually evaluated.
A: Very good (not generated)
B: Good (although slight fixation is observed, there is no influence on the image)
C: Normal (there is sticking or scratching, but there is little effect on the image)
D: Poor (much sticking and causes image defects)

The results based on the evaluation level are summarized in Table 2.
In this embodiment, 1.0 <t _T / T _ed <1.3, that is, T _ed <t _T <1.3 × T _ed is satisfied to prevent toner from remaining for a long period of time. A high-quality image without fog was obtained. As a result, a cleaner-less process was achieved.

[Examples 2 and 3]
The same evaluation as in Example 1 was performed except that the process time was modified to 70 and 80 ms. As shown in Table 2, the results were generally good.
[Comparative Examples 1-4]
The same evaluation as in Example 1 was performed except that the process time was modified to 50 ms, 60 ms, 90 ms, and 110 ms. As shown in Table 2, the results are not T _ed <t _T <1.3 × T _ed , and thus good results were not obtained.

[Examples 4 to 6]
As the photoreceptor, the photoreceptor 2 produced in (Photoreceptor Production Example 2) was used, the developer was used as the developer, and the process time of the image forming apparatus shown in FIG. 4 was modified to 65, 75, and 80 ms. The evaluation was performed in the same manner as in Example 1. As shown in Table 2, the results were generally good.
[Comparative Examples 5 to 8]
The same evaluation as in Example 4 was performed except that the process time was modified to 55 ms, 60 ms, 90 ms, and 100 ms. As shown in Table 2, the results are not T _ed <t _T <1.3 × T _ed , and thus good results were not obtained.

[Examples 7 to 9]
As the photoconductor, the photoconductor 3 manufactured in (Photoconductor Production Example 3) is used, the developer is used as the developer, and the process time of the image forming apparatus (FIG. 5) using the scorotron charging device as the charging unit is set. Evaluation was performed in the same manner as in Example 1 except for modification to 65, 70, and 80 ms. As shown in Table 2, both the image density and the fog suppression were stable and good, the cleaner-less process was achieved, and an excellent image quality was obtained.
[Comparative Examples 9-12]
The same evaluation as in Example 7 was performed except that the process time was modified to 50 ms, 60 ms, 90 ms, and 110 ms. As shown in Table 2, the results are not T _ed <t _T <1.3 × T _ed , and thus good results were not obtained.

[Examples 10 to 12]
As the photoconductor, the photoconductor 4 manufactured in (Photoconductor Production Example 4) is used, the developer is used as the developer, and the process time of the image forming apparatus (FIG. 5) using the scorotron charging device as the charging unit is set. Evaluation was performed in the same manner as in Example 1 except for modification to 65, 75, and 80 ms. As shown in Table 2, both the image density and the fog suppression were stable and good, the cleaner-less process was achieved, and an excellent image quality was obtained.
[Comparative Examples 13 to 16]
The same evaluation as in Example 10 was performed except that the process time was modified to 55 ms, 60 ms, 90 ms, and 100 ms. As shown in Table 2, the results are not T _ed <t _T <1.3 × T _ed , and thus good results were not obtained.

It is the figure which showed the change of the photoreceptor exposure part electric potential with respect to process time. FIG. 5 shows a method for determining process time. 1 is a schematic cross-sectional view of an embodiment of an image forming apparatus of the present invention. 1 is a schematic cross-sectional view of an embodiment of an image forming apparatus of the present invention. It is a schematic cross section of one embodiment of the process cartridge of the present invention. 1 is a schematic cross-sectional view of an embodiment of a photoreceptor in the present invention. 1 is a schematic cross-sectional view of an embodiment of a photoreceptor in the present invention. It is an XD spectrum figure of the titanyl phthalocyanine used in the Example.

Explanation of symbols

1, 1a to 1d: photoconductor 2, 2a to 2d ... charging device (charger)
3, 3a to 3d ... exposure apparatus (laser beam scanning apparatus)
3L: exposure (writing) light 4, 4a to 4d ... developing device 5 ... intermediate transfer belts 6, 6a to 6d, 7 ... transfer device (transfer device)
8 ... Fixer 9 ... Nelectrifier 10, 11, 12 ... Roller 14 ... Electrometer (potential probe) for measuring (reading) the surface potential of the photosensitive member
P ... paper (transfer medium)
DESCRIPTION OF SYMBOLS 100 ... Monochrome image forming apparatus 200 ... Full color image forming apparatus 300 ... Housing 400 ... Process cartridge 401 ... Opening part 402 for static elimination exposure ... Opening part 500 for exposure ... Conductive base | substrate 501 ... Undercoat layer 502 ... Charge transport Layer 503 ... charge generation layer 504 ... photosensitive layer 505 ... protective layer

Claims (21)

At least an image carrier, a charging unit for charging the image carrier, an electrostatic latent image forming unit for forming an electrostatic latent image on a charging surface of the image carrier with a resolution of 1200 dpi or more, and the electrostatic latent image as a toner In an image forming apparatus of a regular development system having a developing means for developing as an image,
The time required for an arbitrary position on the image carrier to move from the position facing the electrostatic latent image forming means to the position facing the developing means is T _ed (ms), and the transit time of the image carrier is t _{When T} (ms), T _ed satisfies the following formula (A).
_{T ed <t T <1.3 ×} T ed ... formula (A)   The image forming apparatus according to claim 1, wherein a plurality of image forming elements having at least an image carrier, a charging unit, an electrostatic latent image forming unit, and a developing unit are used.   The image forming apparatus according to claim 1, wherein the electrostatic latent image forming unit is a multi-beam scanning optical system having a scanning optical unit that forms a plurality of laser beams on the image carrier. apparatus.   The image forming apparatus according to claim 3, wherein a light source included in the multi-beam scanning optical system is three or more surface-emitting laser arrays.   The light source of the multi-beam scanning optical system is a surface-emitting laser array having three or more surface-emitting laser arrays, in which a plurality of light-emitting points are two-dimensionally arranged. The image forming apparatus described in 1. The image carrier has at least a photosensitive layer containing a charge generating material, and the charge generating material contains an azo compound represented by the following general formula (1). The image forming apparatus according to any one of the above.

(In general formula (1), X and Y are each independently the following general formula (2)

(In General Formula (2), R ₃ is a hydrogen atom, an aryl group or an alkyl group, and R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a hydroxyl group, or an alkyl group. , An alkoxy group, a cyano group, a dialkylamino group, a nitro group, a halogen group, or a halogenated alkyl group, and Z may have a carbocyclic aromatic group or a substituent that may have a substituent. It is an atomic group necessary for constituting a heterocyclic aromatic.)
And R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen group. )   The image forming apparatus according to claim 6, wherein X and Y of the azo compound are mutually different coupler residues.   8. The image carrier has a photosensitive layer containing at least a charge generation material, and the charge generation material has a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using CuKα characteristic X-rays. It has strong diffraction peaks at 4 °, 9.6 ° and 24.0 °, the strongest diffraction peak at 27.2 °, and the lowest diffraction peak at 7.3 °. A crystal of titanyl phthalocyanine having a diffraction peak of 7.3 °, no diffraction peak between the diffraction peaks of 9.4 °, and no diffraction peak at 26.3 °. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the image carrier has a protective layer as an outermost layer. The image forming apparatus according to claim 9, wherein the protective layer contains at least one selected from inorganic pigments and metal oxides having a specific resistance of 10 ¹⁰ Ω · cm or more.   The protective layer is formed by curing at least a trifunctional or higher functional radical polymerizable compound having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure. The image forming apparatus according to claim 9. 12. The image forming apparatus according to claim 11, wherein the monofunctional radically polymerizable compound having a charge transporting structure is one or more of the compounds represented by the following general formulas (3) and (4).

(In the general formulas (3) and (4), R ₁ represents a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a cyano group, a nitro group, Group, alkoxy group, general formula -COOR ₂
(Wherein R ₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by the general formula -COY
(In the formula, Y is a halogen group.)
Or a functional group represented by the general formula —CONR ₃ R ₄
(Wherein R ₃ and R ₄ are each independently a hydrogen atom, a halogen group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.)
A functional group represented by
Ar ₁ and Ar ₂ are each independently a substituted or unsubstituted arylene group, Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group, and X is a single bond, substituted or An unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted oxyalkylene group, an oxygen atom, a sulfur atom or a vinylene group, and Z ₁ is a substituted or unsubstituted alkylene group, substituted or unsubstituted Substituted oxyalkylene group or general formula —COOR ₆ —
(In the formula, R ₆ is an alkylene group.)
And m is independently an integer of 0 or more and 3 or less. ) The image forming apparatus according to claim 11, wherein the monofunctional radically polymerizable compound having the charge transporting structure is at least one of compounds represented by the following general formula (5).

(In the general formula (5), o, p and q are each independently 0 or 1, R ₂ is a hydrogen atom or a methyl group, and R ₃ and R ₄ are each independently a carbon number. Is an alkyl group of 1 to 6 and s and t are each independently an integer of 0 to 3, Z ₂ is a single bond, a methylene group, an ethylene group or a structural formula

It is a functional group shown by. )   The image forming apparatus according to claim 11, wherein the protective layer curing means is heating or light energy irradiation means.   An image forming element having at least an image carrier, a charging unit, an electrostatic latent image forming unit, and a developing unit is a cleanerless image forming element having no image carrier cleaning device. The image forming apparatus according to any one of 14.   16. A process cartridge that integrally supports at least one unit selected from the group consisting of an image carrier, a charging unit, and a developing unit, and is detachable from an image forming apparatus main body. A process cartridge which is used for the image forming apparatus described in the item. At least an image carrier, a charging step for charging the image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on a charging surface of the image carrier with a resolution of 1200 dpi or more, and the electrostatic latent image as a toner In the image forming method of the regular development system, which has a development step of developing as an image,
The time required for an arbitrary position on the image carrier to move from the position facing the electrostatic latent image forming unit to the position facing the developing unit is T _ed (ms), and the transit time of the image carrier is t An image forming method, wherein T _ed satisfies the following formula (A) where _T (ms).
_{T ed <t T <1.3 ×} T ed ... formula (A)   The image forming method according to claim 17, wherein a plurality of image forming elements having at least an image carrier, a charging step, an electrostatic latent image forming step, and a developing step are used.   19. The image formation according to claim 17, wherein the electrostatic latent image forming step is a multi-beam scanning optical system having a scanning optical step of forming a plurality of laser beams on the image carrier. Method.   20. The image forming method according to claim 19, wherein the light source of the multi-beam scanning optical system is three or more surface emitting laser arrays.   21. The light source of the multi-beam scanning optical system is a surface emitting laser array having three or more surface emitting laser arrays, wherein a plurality of light emitting points are two-dimensionally arranged. The image forming method described in 1.

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