JP2006301112A - Electrophotographic photoreceptor and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor resulting in favorable image quality and to provide a method for manufacturing the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor comprises an intermediate layer 33 essentially comprising metal oxide and a binder resin, a charge generating layer 35 having charge generating regions containing a charge generating material formed as distributed into dots, and a charge transport layer 37 (a surface layer containing a charge transport material), layered in this order on a conductive support 31. The charge generating regions are formed and distributed by spraying a coating liquid of the charge generating layer by a piezo type ink-jet method. The possession area rate of the charge generating region in the charge generating layer is specified to 90% or less. The dot pitch of the charge generating regions is adjusted to be equal to the resolution of the image forming apparatus. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member used in a copying machine or printer utilizing an electrophotographic process, and a manufacturing method thereof. More specifically, the charge generating layer disperses minute charge generating regions into dots. In other words, the present invention relates to an electrophotographic photosensitive member capable of obtaining high image quality, and a method for manufacturing the same, characterized in that the charge generation layer is dispersed in the form of dots as minute regions. Is.

Conventionally, the photoconductor used in the electrophotographic system includes a photoconductive layer mainly composed of selenium or a selenium alloy on a conductive support, and inorganic photoconductive materials such as zinc oxide and cadmium sulfide. Are generally known, such as those in which binder is dispersed in a binder, and those using an amorphous silicon-based material. However, cost, productivity, high degree of freedom in designing a photoreceptor, non-polluting, etc. Therefore, organic photoreceptors are widely used.
The organic electrophotographic photoreceptor includes a photoconductive resin typified by polyvinylcarbazole (PVK), a charge transfer complex type typified by PVK-TNF (2,4,7-trinitrofluorenone), Known are pigment-dispersed type typified by phthalocyanine-binder resin, and function-separated type photoconductors that use a combination of a charge generation material and a charge transport material. However, due to sensitivity, durability, and freedom of design, etc. A function-separated type photoreceptor in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated on a conductive support is common.
The mechanism of electrostatic latent image formation in this function-separated type photoreceptor is that when the photoreceptor is charged and irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generation material in the charge generation layer, The charge generation material that has absorbed the light generates charge carriers, which are injected into the charge transport layer, move in the charge transport layer according to an electric field, and neutralize the charge on the surface of the photoreceptor to neutralize the electrostatic latent. It forms an image. In function-separated type photoreceptors, it is known and useful to use a combination of a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly from the visible region to the near infrared region. It is.

However, in the case of the above-described function-separated type photoreceptor, since the distance from the charge generation layer to the surface of the charge transport layer is long, there is a problem that the carrier is diffused during transport and the resolution is lowered. In other words, the carriers are attracted to the surface of the charge transport layer and transported, but at that time, they are also diffused in the lateral direction, the carrier diameter is larger than the beam spot diameter corresponding to one dot, and the adjacent image. The dot area is entered (see FIG. 1).
Furthermore, since the energy distribution of the exposure beam follows a Gaussian function (normal distribution), it will have a wide skirt, and carriers generated by the light at this skirt will easily diffuse into the adjacent image dot area, and the resolution will increase. Is a cause of lowering. FIG. 2 shows this, and shows the energy (I) distribution of an exposure beam of 600 dpi and a beam diameter of 68.9 μm. In the figure, when it has energy distribution of A and B, it becomes energy distribution C as a whole.
Further, in an electrophotographic image forming apparatus, the beam spot diameter of a laser beam for exposing a photosensitive drum (the diameter of a circle connecting regions showing an amount of light that is 1 / e ² of the peak value. E is the base of the natural logarithm. Are mostly in the range of 50 μm to 80 μm. When the resolution is 1200 dpi, the length per pixel is 21.2 μm, which is considerably smaller than the beam diameter. Since the beam diameter is determined by the wavelength of the laser, the focal length of the optical system, and the aperture diameter, reducing the beam diameter alone involves problems such as increasing the size of the device. There is a background that cannot be done.

  The problem that the beam spot diameter is larger than the length per pixel and the problem that occurs in the above-described function-separated type photoconductor (laminated photoconductor), that is, when the photocarrier passes through the charge transport layer. When combined with the problem that photocarriers diffuse into the surface area of the charge transport layer and enter adjacent pixel areas, conventional image forming apparatuses have a sharp electrostatic latent image (potential (charge (charge)). ) There is a problem that it is difficult to form an electrostatic latent image having a high contrast.

  When such an electrostatic latent image with a small potential contrast is formed through development, transfer, and fixing processes, the following phenomenon that leads to deterioration in image quality may occur. However, it became clear by the experiment which the present inventors conducted.

[First image quality degradation phenomenon: disappearance of fine lines]
When one dot line (thin line) is formed when the resolution is high (in the case of 1200 dpi), a phenomenon occurs in which the one dot line disappears and is not reproduced in the output image. In addition, even when the resolution is small (in the case of 600 dpi), when half dot writing (writing with a small value at the time of multi-value writing) is performed, the thin line disappears in the same manner and is not reproduced. Will occur. These thin line images and images having characteristics close to those exist as low-contrast images (images such as lines and characters that appear to be very light gray) even in general images. For this reason, even in a general image, a reduction in image quality such as a decrease in reproducibility of a low contrast image is caused.

[Second Image Quality Degradation Phenomenon: Abrupt Density Change at Highlight Area in Tone Image]
When a gradation image such as a photographic image or a graphics image is subjected to pseudo halftone processing with a high number of lines and output as an image, a highlight portion (an area having a reflection density of about 0 to 0.2) ) Causes a sudden change in density. In such a gradation image, such a sudden density change at the highlight portion causes a phenomenon called a pseudo contour that a gradation boundary that does not exist on the original image appears. Since the pseudo contour is an abnormal image that gives a sense of incongruity in a gradation image, it is a major factor in image quality degradation.

On the other hand, in an electrophotographic photoreceptor in which at least a photosensitive layer is formed on a conductive substrate, the photosensitive layer includes a charge generation region and a charge transport region, and the charge generation region is provided in the charge transport region. An electrophotographic photosensitive member characterized by a structure embedded in a hole is disclosed (for example, see Patent Document 1), but is expensive because the manufacturing process is complicated, and the surface layer has a region. Since they are separated from each other, adhesion of foreign matter, indentation and the like are likely to occur, and as a result, an abnormal image is likely to occur.
Further, in the function separation type photoreceptor in which the base, the carrier generation layer, and the carrier transport layer are sequentially laminated, a light shielding mask pattern layer that blocks a part of the image exposure light is provided at least on the surface of the carrier generation layer. An electrophotographic photoreceptor characterized by this is disclosed (for example, see Patent Document 2), but is also expensive due to the complicated manufacturing process, and contamination is caused by the material of the light-shielding mask pattern. As a result, problems in electrostatic characteristics arise.
Further, in the multilayer electrophotographic photosensitive member including a charge generation layer and a charge transport layer, the charge transport layer contains a photocurable resin and another resin component, and the photocurable resin is added when the charge transport layer is formed. By irradiating light in a wavelength region that can be cured in a lattice shape, a portion in which the content of the photocurable resin is larger than the unexposed portion is formed in a lattice shape, and the lattice-shaped exposed portion has surface resistance or volume resistance. An electrophotographic photosensitive member characterized in that it is an area larger than an unexposed portion is disclosed (for example, see Patent Document 3). However, since the manufacturing process is complicated, it is expensive. When a curable resin is used, the carrier mobility generally decreases, and the photoresponsiveness as a photoreceptor greatly decreases. Further, since the pattern is formed in a lattice pattern, it cannot be said that the effect of suppressing the reduction in resolution is great.
In addition, in an image forming apparatus that forms a visible image by charging, image exposure, and development on the surface of an image carrier on which a photoconductive photosensitive layer is formed, a minute region in which the potential is not attenuated with respect to the image exposure. An image forming apparatus characterized in that is formed in a dispersed manner in the photosensitive layer (see, for example, Patent Document 4), but improves the image density uniformity of solid images and graphics. Although it is effective, it is considered ineffective to improve the resolution. The production method is also formed by laser beam irradiation, and the process is complicated and the influence on the electrostatic properties of carbides generated by laser beam irradiation cannot be ignored.
Further, an electrostatic latent image carrier including a carrier generation layer disposed in a lattice pattern in at least two types of carrier generation portions having different sensitivity wavelength ranges, and exposure means for performing optical writing on the electrostatic latent image carrier An image forming apparatus including an exposure unit having an emission wavelength corresponding to the sensitivity wavelength of each carrier generation layer portion is disclosed (for example, see Patent Document 5). The lattice patterning creation method described is unclear (lattice patterning is not possible with the ink jet method). In exposure at 550 nm, both of the two types of carrier generating substances are sensitive, and the bottom of the beam spot is substantially reduced. The spread cannot be cut and high resolution cannot be achieved.

In the above-described conventional techniques (Patent Documents 1 to 5), problems such as those already described (cost increase due to the complexity of the production method, reduction in durability due to non-uniformity of the light shielding pattern and the charge transport layer, and the like) It is not efficient enough not only to cause problems) but also to form an electrostatic latent image having a large potential contrast.
In the prior art described above, the generation ratio (so-called sensitivity) of photocarriers generated in the CGL (charge generation layer) is constant in any part of the CGL (any part of the unmasked part). In such a configuration, in combination with the current situation that the beam spot diameter cannot be actively reduced, the photocarrier generated in the unmasked portion is almost constant in the unmasked region. It becomes. In this case, the photocarrier generation region is slightly concentrated by the mask region. However, since the effect is limited to the size of the mask region, an electrostatic latent image having a sufficiently large contrast ( There is a problem in that an electrostatic latent image having a contrast that cannot be obtained so as not to cause the problems such as disappearance of fine lines and abrupt density change in a highlight portion in a gradation image described in the previous page.
For the above problem (problem in which an electrostatic latent image having a sufficiently high contrast cannot be formed), the mask area is further increased (the charge generation area is reduced), and the photocarrier generation location is set to one pixel. Improvement is also possible by limiting to the central part. However, in this case, there is a new problem that a so-called solid image (an image in which toner is uniformly attached to the entire region) cannot be obtained. This is because if the masked area is made large, the charge in this part cannot be canceled by writing, and toner cannot adhere to this part.
In addition to the above-mentioned problems, if an intermediate layer is not provided on the conductive support, the surface roughness of the conductive support and the influence of cutting unevenness will occur, and the effect of improving the image quality will be uniform over the entire image. There are also problems that cannot be realized. Furthermore, there remains a problem that the effect of improving the image quality fluctuates due to the influence of the abrasion of the surface layer, and therefore the image quality fluctuates with time.

JP 2000-231203 A JP 2001-75301 A JP-A-11-258837 JP 11-338170 A JP 2003-202681 A

The present invention has been made in view of the above points, and an object of the present invention is to provide an electrophotographic photosensitive member that provides good image quality. Further, it is possible to provide an excellent electrophotographic photosensitive member production method and an electrophotographic photosensitive member which are low in cost and do not cause any problem in electrostatic characteristics without using a complicated preparation method seen in the past. With the goal. In addition, the present invention provides a method for producing an electrophotographic photosensitive member that does not require complicated steps and does not have non-uniformity of a light-shielding pattern or a charge transport layer, and can also achieve durability in terms of electrostatic characteristics. is there.
Another object of the present invention is to propose an electrophotographic photosensitive member that can uniformly adhere toner to the entire surface of a solid image while forming an electrostatic latent image having a sufficiently large contrast. To do.

That is, as a result of intensive studies, the present inventors can solve the above-mentioned problems by forming the charge generation layer as a minute region dispersed in dots as compared with the conventional electrophotographic photosensitive member and its manufacturing method. I found.
Further, since the material itself constituting the electrophotographic photosensitive member of the present invention does not use a light-shielding material or a curable material, it can be used without changing from the conventional photosensitive member, and is easily and accumulated. By using the photoconductor technology, it is possible to easily design a photoconductor corresponding to high sensitivity and high image quality.
That is, according to the present invention, the above-described problem is solved by the present invention.
(1) In an electrophotographic photosensitive member comprising an intermediate layer, a charge generation layer, and a surface layer containing a charge transport material on a conductive support, the intermediate layer mainly comprises a metal oxide and a binder resin. An electrophotographic photosensitive member characterized in that it is formed as a component, and the charge generation layer is formed by dispersing minute charge generation regions containing a charge generation material in the form of dots. "
(2) “The ratio of the charge generation region dispersed in the dot shape in the charge generation layer, that is, the area ratio of the charge generation region in the charge generation layer (charge generation region area ratio) is 90% or less. The electrophotographic photosensitive member according to (1), wherein the electrophotographic photosensitive member is (1) and has an occupation area ratio (X) or more represented by the following formula (1):
η × J ≧ 0.01 × EXP (− (X−60) / 10) +0.002 (1)
(Η indicates quantum efficiency, J indicates exposure beam energy (J / m ² ), and “EXP” indicates “exponential”.)
(3) “The electrophotographic photosensitive member according to (1) or (2) above, wherein the dot pitch is equal to the resolution of the image forming apparatus.”
(4) “The electrophotographic photosensitive member according to any one of (1) to (3) above, wherein the surface layer is formed using at least one kind of a crosslinkable compound.”
(5) “The electrophotographic photosensitive member according to (4) above, wherein the crosslinkable compound is a charge transporting compound containing a nitrogen atom in the structure.”
(6) “A siloxane-based resin obtained by reacting a charge transporting compound having a reactive group with at least one of an organosilicon compound having a hydroxyl group or a hydrolyzable group and a condensate thereof” The electrophotographic photosensitive member according to (4) or (5) above, which is contained.
(7) The above-mentioned (6), wherein the surface layer comprises at least a radically polymerizable monomer having no charge transporting structure and a crosslinked layer obtained by curing a radically polymerizable compound having a charge transporting structure. Electrophotographic photoreceptor. "
(8) “A functional group of a radical polymerizable monomer having no charge transporting structure and / or a functional group of a radical polymerizable compound having a charge transporting structure used for the surface layer is an acryloyloxy group and / or methacryloyloxy. The electrophotographic photosensitive member according to (7) above, which is a group.
(9) The electrophotographic photosensitive member according to any one of (1) to (8) above, wherein the average particle size of the charge generation material contained in the charge generation region is 0.2 μm or less. "
Is achieved.
In addition, the above problem is
(10) “A method for producing the electrophotographic photosensitive member according to any one of (1) to (9) above, wherein the charge generation region is formed by ejecting a charge generation layer coating solution by an inkjet method. A method for producing an electrophotographic photosensitive member characterized by comprising:
(11) “The method for producing an electrophotographic photosensitive member according to (10) above, wherein the inkjet method is a piezo method.”
Is achieved.

According to the first aspect of the present invention, by forming a charge generation layer by dispersing minute charge generation regions in a dot shape and using a specific intermediate layer, it is possible to produce a gradation image such as a photographic image or a graphics image. On the other hand, even when image output is performed by performing pseudo halftone processing with a high number of lines, there is no abrupt density change in the highlight portion (region where the reflection density is about 0 to 0.2), and further reproduction is performed. A good quality image can be obtained.
Further, according to claim 2 of the present invention, by setting the occupied area ratio in the charge generation layer of the charge generation region formed in a dot shape to 90% or less and within the range of the above formula (1), It is possible to obtain an image satisfying both “good reproduction of” and “stable density change in the highlight portion”. Even if it is placed on a solid black image, a sufficient image density can be obtained.
According to claim 3 of the present invention, the effect shown in claims 1 and 2 becomes more remarkable by making the pitch of the dots equal to the resolution of the image forming apparatus.
According to the fourth aspect of the present invention, it is possible to obtain an image with high image quality and superior stability over time.
According to the fifth to eighth aspects of the present invention, it is possible to obtain an electrophotographic photosensitive member having stable electrostatic characteristics, excellent wear resistance, and extremely excellent image quality.
According to the ninth aspect of the present invention, when the charge generation material contained in the charge generation region has an average particle diameter of 0.2 μm or less, dot reproducibility is improved, and unevenness of the entire image is reduced, which is good. An image can be obtained.
In addition, according to claim 10 of the present invention, the formation of the charge generation layer, that is, the application of the charge generation region, is performed using an ink jet method, so that the formation of dots can be achieved with an extremely simple manufacturing apparatus as compared with the conventional case. In addition, it can be performed at low cost.
Further, according to the eleventh aspect of the present invention, by using a piezo method as the ink jet method, it is possible to prevent the charge generation layer coating solution which is easily deteriorated by heat from being changed, and to apply the coating by the bubble jet (registered trademark) method. It is possible to prevent black spots on the image which are concerned when processed, and to provide a manufacturing method that can bring out the effects of the present invention very well.

The present invention relates to an electrophotographic photosensitive member comprising an intermediate layer, a charge generation layer, and a surface layer containing a charge transport material on a conductive support, wherein the intermediate layer mainly comprises a metal oxide and a binder resin. It is an invention relating to an electrophotographic photosensitive member characterized in that it is formed as a component, and the charge generation layer is formed by dispersing minute charge generation regions containing a charge generation material in the form of dots, more preferably The occupied area ratio in the charge generation layer of the charge generation region dispersed in the dot form is 90% or less and the occupied area ratio (X) represented by the following formula (1): The invention relates to a characteristic electrophotographic photosensitive member, which makes it possible to uniformly adhere toner to the entire surface of a solid image while forming an electrostatic latent image having a sufficiently high contrast. It is possible to obtain a true photoconductor high stability.
η × J ≧ 0.01 × EXP (− (X−60) / 10) +0.002 (1)
(Η represents quantum efficiency, and J represents exposure beam energy (J / m ² ).)

  The quantum efficiency η in the above formula (1) is calculated by the following formula (2).

Here, C is a capacitance per unit area of the photoreceptor, e is an elementary charge of electrons, J is monochromatic light energy, V is a surface potential, and t is time. The quantum efficiency η is a physical quantity independent of the film thickness and represents carrier generation efficiency (quantum efficiency of photoelectric conversion). The quantum efficiency η is obtained from a transient attenuation characteristic when monochromatic light (energy J per unit time) is exposed and the photosensitive member capacitance C, and is calculated by fitting to an electric field dependency formula, η = αE ^n. .

The measurement of the static beam light quantity J (the exposure beam energy is hereinafter referred to as the static beam light quantity) was performed as follows. An optical power meter (model 3292) manufactured by Yokogawa Electric Corporation was used for measurement of the amount of static beam. The probe (light receiving portion) of this optical power meter was placed at the laser beam imaging position (corresponding to the position where the photosensitive drum is placed) and set so that the laser beam was incident on the probe center. In this state, the output value of the optical power meter was recorded while the LD (laser diode) was continuously turned on, and the light amount was taken as a stationary beam amount.
When the occupation area ratio of the charge generation layer formed in the dot shape (charge generation region dispersed in the dot shape) is larger than 90%, an electrostatic latent image having a sufficiently large contrast can be formed. However, a sharp density change is observed in the highlight portion (region where the reflection density is about 0 to 0.2), and the effect of the present invention cannot be obtained.

The above formula (1) shown in the present invention is obtained from the reproducibility of isolated dots and the uniformity and density of a black solid image, and is obtained by conducting further experiments after examination from the following simulation. It is a thing.
The simulation method is as follows.
The relationship between the area occupied by the charge generation layer formed in a dot shape and the toner adhesion amount when the photosensitive member sensitivity and the exposure energy amount were varied was calculated by simulation.
It is known that the charge density distribution on the photoreceptor after exposure can be roughly grasped by using a PIDC curve. However, the difference in latent image distribution due to the effect that carriers generated in the CGL layer diffuse while moving through the CTL layer when the thickness of the photoconductor is changed, or in the vicinity of the CGL in the case of strong exposure. When analyzing the influence of the difference in latent image distribution caused by the recombination of positive and negative carriers with a PIDC curve, it is necessary to measure PIDC for each condition and for each film thickness. Further, it can be dealt with by actually measuring a PIDC curve at the time of a dot image, but it is impossible to measure a one-dot latent image distribution or potential distribution on a photoconductor with the current technology.
Therefore, the movement of carriers (charges) inside the photoconductor correctly takes into account the Coulomb repulsion between carriers, the recombination of carriers, and the mobility of carriers inside the photoconductor, and the latent image distribution and potential distribution are simulated. Need to predict.

The calculation method is described below. The calculation method consists of the following three steps.
(I) Calculation of latent image charge distribution The latent image charge distribution on the photoreceptor after exposure is calculated. The movement of the carrier (charge) inside the photoconductor is affected by the Coulomb repulsion between the carriers, recombination of the carriers, and the mobility of the carrier inside the photoconductor. Formation simulation is required.
The physical model used to calculate the latent image charge distribution consists of (1) calculation of exposure amount by a Gaussian laser beam, and (2) calculation of charge carrier generation and its transport process.
In the exposure amount calculation, the exposure amount distribution of a single stationary beam, that is, I (x, y) is expressed by the following equation (3).

(Where x-vt: distance from the laser center, y: distance from the laser center, ω: laser beam radius (1 / e ^{2 of} center intensity), P ₀ : laser power), and X direction It is calculated by integrating in the X direction for the moving distance (Vx · spotting time) during the lighting time.
When this amount of exposure is applied to the dot-like charge generation layer, only the portion where the charge generation region exists is actually exposed. Therefore, the region without the charge generation region (so-called non-charge) in the charge generation layer. The exposure distribution in the generation area) is deleted, and only the exposure distribution in the charge generation area is extracted, and this is used as the exposure distribution.
Next, the charge carrier generation and transport process of the above (2) in OPC are carried out according to the following positive and negative carrier equation (Equation (4), Equation (5)) and Poisson equation (Equation (6)). ).

  Here, n, μ, E, Γ, R, ε, and e are the number density of carriers, mobility, electric field strength, amount of carriers generated per unit time, recombination coefficient per unit time of carrier, dielectric Rate and elementary charge. Subscripts p and n indicate positive and negative carriers, respectively.

Charge carriers were assumed to be generated uniformly in the layer, taking into account the thin CGL layer. For this reason, the carrier generation amount Γ is connected to the incident light intensity F, the quantum efficiency η, and the thickness d of the CGL layer in the following relationship.
Γ = β · η · F / (d · hυ) (7)
Here, β and hν are the light absorption efficiency in the CGL layer and the energy per photon of the laser beam, respectively.

In addition, the carrier recombination term of the second item on the right side of the above formulas (4) and (5) is used to explain that the amount of generated carriers decreases experimentally when positive and negative carriers coexist in the same vicinity. It has been introduced.
Among the above physical quantities, the light absorption coefficient β and the recombination coefficient R are calculated by performing experimental fitting from the surface potential at the time of black solid exposure.
Further, the quantum efficiency η is a value obtained from the above formula (2), as described above.
Before the exposure, it is assumed that the photoreceptor is uniformly charged, and the charge amount on the surface of the photoreceptor is calculated. Thereafter, by calculating the above formula on the assumption that carriers are generated in the exposure region, the charge density distribution on the photoreceptor after exposure is calculated.
As a calculation method, a difference method regarding n _p , n _n , and φ was adopted. Here, φ represents a potential. The time forward difference (the following formulas (8) and (9)) is used for the continuous expression of charge carriers, that is, the time differential terms of the above formulas (4) and (5), and Uses the upstream differential method (the following equation (10)). Except for the time derivative term, a complete implicit method that evaluates implicitly is used.

  Here, δt, n, and n + 1 are a time step, a step number indicating the calculated current step, and a step number indicating the next future step, respectively.

The nonlinear algebraic equation thus obtained is calculated using a double iteration method. First, the entire three formulas (formulas (8) to (10)) are calculated using the successive approximation method. In this iteration, the equations (8) and (9) are variables other than those appearing in the time derivative term, for example, in equation (8), values other than n _p use values of known iteration results. First of all, this formula is calculated based on Successive Over Relaxation. The Poisson equation (formula (10)) performs the same calculation for φ. Iterates until the residual by the successive approximation method for the whole expression reaches a specified value. Here, designated values are designated for φ, n _n , and n _p, respectively, and are 5 × 10 ⁻³ , 1 × 10 ⁻² , and 1 × 10 ⁻² .

(II) Calculation of development electric field strength distribution The development electric field strength distribution is calculated from the latent image charge distribution on the photoreceptor obtained in (I) and the development conditions. It is assumed that the developing sleeve and the photoconductor are approximated by parallel plates, and the developer (carrier and toner) is uniformly filled between them. That is, the developer is treated as a uniform dielectric layer having an average dielectric constant. Here, the average dielectric constant is the product of the average dielectric constant and the vacuum dielectric constant, and the average dielectric constant ε ′ is ε ′ = a · ε _l + (1−a) (11)
It is obtained with. Here, ε _l is the relative dielectric constant of the carrier, and a is the proportion of the volume occupied by the carrier in the development nip.
The potential distribution can be obtained by solving the Poisson equation with the sleeve surface as the developing bias potential, the photosensitive member lower surface as the constant OV boundary condition, and the left and right boundaries as the periodic boundary conditions. At the surface of the photoreceptor E = −gradφ (12)
Is obtained, the development electric field strength distribution on the surface of the photoreceptor is obtained.

(III) Calculation of toner adhesion amount The toner adhesion amount is calculated from the electric field strength distribution obtained in (II) and the development conditions.

Here, k is a toner adhesion coefficient, v _r / v _p is a sleeve linear velocity ratio, 1 is a developing nip width, R is a carrier radius, ε ₀ is a dielectric constant, and q is a toner charge amount.

Beam spot diameter (main scanning x sub-scanning) 50 x 65 (μm)
Resolution 1200 dpi
Quantum efficiency 2.83 * 10 ^-5 * e ^0.5933 ("*" is a multiplication symbol)
Initial charging potential -650v
OPC film thickness 28μm
Power variable Image pattern 2 * 2 dots Charge generation area ratio x
Exposure energy y

FIG. 3 shows the relationship between the charge generation region area ratio and the toner adhesion amount obtained by the simulation.
As the charge generation region area ratio increases, the toner adhesion amount increases. Further, by increasing the exposure energy (a measurement line having a small gradient is a case where the exposure energy is small, and corresponds to a measurement line having a large gradient as the exposure energy increases), the toner adhesion amount increases.
Here, the relationship between the charge generation region area ratio x and the toner adhesion amount M is:
M = ax ² + bx + c (14)
Can be approximated.
Here, the coefficients a, b, and c can be approximated by a linear expression of Power. Therefore, the relationship between the charge generation area area ratio x and the toner adhesion amount M is M = a (p) x ² + b (p) x + c (15)
Can be expressed as
Here, since the toner adhesion amount per unit area is 0.45 mg / cm ² or more for the reproducibility of the black solid image and the image density required for the black solid image, the toner adhesion required amount is (16). In this equation, “*” is a multiplication symbol (the same applies hereinafter).

Next, FIG. 4 shows the relationship between the charge generation region area ratio (DM ratio (%)) satisfying the toner adhesion amount M ≧ 0.45 mg / cm ² and the quantum efficiency * Energy.
It can be seen that the quantum efficiency * Energy and the area ratio of the charge generation region have a certain relationship regardless of the OPC type.
This is expressed by the following equation (17).

It can be seen that Here, two types of OPC were calculated with different resolutions, and a = 0.01, b = 60, and c = 0.002 were obtained.
The charge generation region area ratio x can be measured by using an optical microscope, a laser microscope, or the like.

Next, the intermediate layer will be described. As the pigment used for the intermediate layer, it is better to use a metal oxide having a large refractive index in order to prevent the occurrence of moire. For example, titanium oxide or zinc oxide is preferably used. Further, the metal oxide to be used preferably has a purity of 99.0% or more. This is because the impurities contained in the metal oxide are hygroscopic substances such as Na ₂ O and K ₂ O and ionic substances. Mainly, when the purity of titanium oxide is lower than 99.0%, the characteristics of the photoreceptor are largely caused by the environment (especially humidity) and repeated use. Further, these impurities are liable to cause image defects such as black spots.

Furthermore, in the present invention, the ratio (P / R) of the metal oxide (P) and the binder resin (R) in the intermediate layer can be maintained in the range of 0.8 / 1 to 3/1 by volume ratio. preferable. If the P / R ratio of the intermediate layer is less than 0.8 / 1, the intermediate layer depends on the characteristics of the binder resin, and the characteristics of the photoreceptor change particularly with changes in temperature and humidity. For example, the residual potential becomes large at low humidity, and the chargeability decreases at high humidity. On the other hand, when the ratio exceeds 3/1, the space in the intermediate layer increases, and air accumulates and bubbles are formed during coating and drying of the charge transport layer, resulting in coating film defects.
As a preferable reason for using the intermediate layer of the present invention, it is possible to reduce the environmental dependency as described above by using a metal oxide, and furthermore, by using a metal oxide, energy by exposure can be efficiently applied to the charge generation layer. Propagation can easily achieve high sensitivity as a photoconductor, and the coating film mixed with the binder resin by P / R shown in the present invention has high concealability to the conductive support and is applied uniformly. This is because the image quality defect caused by the conductive support can be prevented and the uniformity of the high quality image can be improved.
As the binder resin used in the present invention, an appropriate one can be used. However, considering that the photosensitive layer is coated with a solvent thereon, a resin having high solvent resistance with respect to a general organic solvent is desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resins, and epoxy resins. Examples thereof include a curable resin to be formed.
The thickness of the intermediate layer is preferably about 0.5 to 50 μm, particularly preferably 1.0 to 25 μm.

Next, the ink jet method which is a manufacturing method used in the present invention will be described.
The ink jet method is a method used in an ink jet printer. Recently, an ink jet recording method using this ink jet method has begun to spread widely. This ink jet recording method is a printing method in which printing is performed by causing small droplets of an ink composition to fly and adhere to a recording medium such as paper. An ink jet recording apparatus using this method has a feature that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. For this reason, ink jet recording apparatuses have come to be used as digital printing machines, plotters, CAD output devices, and the like. In particular, since the ink jet recording apparatus can print a digitally processed sentence or image, it can store a document or an image original semipermanently and can print the contents. The ink jet recording apparatus can realize high analysis and high pixel printing by discharging ink composition droplets from a recording head under appropriate system processing.

  That is, the ink jet method can attach small droplets to a specific place so that photographic image quality can be output, and there is almost no loss as a liquid. Therefore, it is possible to form a high-quality coating film at low cost as a liquid. In addition, as used in digital equipment, the ON / OFF of droplet flight can be digitally controlled, so that liquid can be output and applied only where needed, and unnecessary parts can be easily removed. It can be uncoated. In addition, equipment such as nozzle heads used in the ink jet method can be easily obtained at low cost and with high quality and high stability due to the widespread use of ink jet printers. Does not require large-scale equipment. Further, as can be seen from the recent trend of inkjet printers, productivity can be dealt with by increasing the number of nozzles, and productivity can be easily improved.

  As an ink jet method used in the manufacturing method by the ink jet method of the present invention, a bubble jet (registered trademark) type using an electrothermal transducer as an energy generating element or a piezo jet type using a piezoelectric element can be used. It is. However, the piezo-type ink jet method only applies pressure to the ink and basically has no degradation effect on the ink, whereas the bubble-type ink-jet method instantaneously moves the micro heater embedded in the nozzle. In any case, since the ink is ejected by heating to 200 to 300 ° C. and generating bubbles, the ink has a deterioration action such as kogation. Due to the influence of this kogation, the background stain of the image may occur, and the piezo jet type is preferably used in consideration of the influence of heat or the like on the ink, that is, the coating liquid. Also, by changing the ink jet nozzle and pressurizing / heating time, the amount of ink per ink drop and the amount of ink applied per colored part can be set arbitrarily, so that charge generation is important in the present invention. It becomes possible to control the dot shape (diameter) of the layer.

Hereinafter, the electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 6 shows an intermediate layer (33) containing a metal oxide and a binder resin, a charge generation layer (35) containing a charge generation material as a main component, and a charge transport material on a conductive support (31). The charge transport layer (37) to be contained is laminated.
FIG. 7 shows a structure in which a protective layer (39) formed using at least one kind of crosslinkable compound is provided on the charge transport layer (37) as a surface layer in FIG.
(Although the charge generation layer shown in these drawings is drawn as a uniform layer, it is needless to say that the charge generation layer is actually formed by being dispersed in the form of dots as minute regions.)

Examples of the conductive support (31) include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium by vapor deposition or sputtering, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel plates, etc. and methods such as extrusion and drawing After forming the tube, it is possible to use a tube subjected to surface treatment such as cutting, superfinishing or polishing. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (31).
In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support (31) of the present invention.

Next, the charge generation layer (35) is a layer mainly composed of a charge generation material, in which the charge generation material, the binder resin or the like is dispersed or dissolved in an appropriate solvent, and this is formed on the conductive support or in the middle. It can be formed by coating and drying on the layer.
As the charge generation layer (35), a known charge generation material can be used, and representative examples thereof include phthalocyanine pigments such as titanyl phthalocyanine, vanadyl phthalocyanine, copper phthalocyanine, hydroxygallium phthalocyanine, and metal-free phthalocyanine, monoazo pigments, Known azo pigments such as disazo pigments, asymmetric disazo pigments, trisazo pigments, perylene pigments, perinone pigments, indigo pigments, pyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squalium pigments, etc. Materials, which are usefully used. These charge generating materials can be used alone or in combination of two or more.
In the charge generation layer (35), the charge generation material is dispersed in a suitable solvent together with a binder resin if necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is applied onto the conductive support. And formed by drying. The particle size of the charge generation material is preferably 0.2 μm or less. In the case of 0.2 μm or more, since dots are not formed cleanly and uniformly, the resolution of isolated dots is lowered. In particular, the influence becomes significant when a high resolution of 1200 dpi or more and a writing system of a small diameter beam are used.
The binder resin used for the charge generation layer (35) as necessary may be polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly -N-vinyl carbazole, 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 Etc. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material. The binder resin may be added before or after dispersion.
Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, and ligroin. In particular, ketone solvents, ester solvents, and ether solvents are preferably used. These may be used alone or in combination of two or more.
The charge generation layer (35) is mainly composed of a charge generation material, a solvent, and a binder resin, and includes any additive such as a sensitizer, a dispersant, a surfactant, and silicone oil. May be.
As a coating method for the charge generation layer coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. As shown in the present invention, an ink jet method is preferable.
The film thickness of the charge generation layer (35) is suitably about 0.01-5 μm, preferably 0.1-2 μm.

The charge transport layer (37) can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, it is possible and useful to add one or two or more kinds of plasticizers, leveling agents, antioxidants, lubricants and the like as necessary.
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. These may be used alone or in combination of two or more.
As a coating method of the coating solution, methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used.
The charge transport material is classified into a hole transport material and an electron transport material. Examples of the electron transporting material include chloroanil, 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-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
Examples of hole transport materials include 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, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. Other known materials may be used. These charge transport materials may be used alone or in combination of two or more.
As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
Moreover, it is preferable that the film thickness of a charge transport layer shall be 5-40 micrometers or less. The lower limit varies depending on the system to be used (particularly charging potential), but is preferably 5 μm or more.

A protective layer (39) formed using at least one kind of crosslinkable compound may be formed on the charge transport layer (37) for the purpose of improving durability.
As the protective layer, for example, a layer containing a hole transporting hydroxyarylamine having a hydroxy functional group and a polyamide film forming binder capable of forming a hydrogen bond with the hydroxy functional group (Japanese Patent Laid-Open No. 7-253683) ), A hydroxyarylamine compound having a hydroxy functional group in a thermosetting polyamide resin, a curing catalyst, a film cured by heating after coating (US Pat. No. 5,670,291), an alkoxysilyl group A layer cured with a charge transport compound and an alkoxysilane compound (JP-A-3-191358), a cured layer using an organopolysiloxane and colloidal silica, and a conductive metal oxide and an acrylic resin ( JP-A-8-95280), a conductive metal oxide having a silicon functional group Layer cross-linked with acrylate (JP-A-8-160651), layer cross-linked with conductive metal oxide with photocurable acrylic monomer or oligomer (JP-A-8-184980), charge containing epoxy group A layer cured with a transporting compound (Japanese Patent Laid-Open No. 8-278645), a diamond-like carbon containing hydrogen, or a layer of crystalline carbon containing amorphous carbon or fluorine (Japanese Patent Laid-Open No. 9-101625, Kaihei 9-160268, JP-A-10-73945, a layer mainly composed of cyanoethyl pullulan (JP-A-9-90650), a layer obtained by crosslinking a silyl acrylate compound and colloidal silica (JP-A-9-319130). No.), a layer using a polycarbonate graft copolymer (Japanese Patent Laid-Open No. 10-630) 6), a layer obtained by curing colloidal silica particles and a siloxane resin (Japanese Patent Laid-Open No. 10-83094), a layer cured with a charge transporting compound containing a hydroxy group and an isocyanate group-containing compound (Japanese Patent Laid-Open No. 10-177268). And a cross-linked layer obtained by curing a radical polymerizable acrylic monomer having no charge transporting structure and a radical polymerizable acrylic compound having a charge transporting structure (Registered No. 3194392, JP 2000-66424 A). .
In particular, as shown in the present invention, it comprises a siloxane-based resin obtained by reacting a charge transporting compound having a reactive group with an organosilicon compound having a hydroxyl group or a hydrolyzable group and its condensate. It is preferable to use a protective layer composed of a crosslinking layer obtained by curing a radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a charge transporting structure. Furthermore, it is preferable to use a compound in which the functional group of a radically polymerizable monomer having no charge transporting structure and / or a radically polymerizable compound having a charge transporting structure is an acryloyloxy group and / or a methacryloyloxy group.
The reason why it is preferable to use a protective layer formed by using at least one kind of crosslinkable compound as the surface layer as described above is that a photoreceptor composed of ordinary CTL has poor wear resistance, and the charge generation layer is very small. While the image quality cannot be maintained over time due to being dispersed in the form of dots as a region (image quality is not stable), the image quality improvement over time can be achieved by using the protective layer. Depending on what can be maintained. In particular, as shown in the present invention, it comprises a siloxane-based resin obtained by reacting a charge transporting compound having a reactive group with an organosilicon compound having a hydroxyl group or a hydrolyzable group and its condensate. The use of a protective layer comprising a protective layer, a crosslinkable layer obtained by curing a radically polymerizable monomer having no charge transporting structure and a radically polymerizable compound having a charge transporting structure can impart charge transportability to the protective layer, An electrophotographic photosensitive member that has higher image quality stability because it can provide wear properties, and can obtain a crosslinked layer that is excellent in environmental dependence, so that it is less likely to cause image blurring that is a problem with a photosensitive member that has excellent wear resistance. Can be obtained.
The film thickness of the entire protective layer is 1 μm to 10 μm, preferably 2 to 6 μm. If the protective layer thickness is extremely thin, the uniformity of the film may be reduced or sufficient wear resistance may not be obtained.If the thickness is extremely thick, there is an effect of an increase in residual potential. In some cases, the resolution or dot reproducibility may decrease due to an increase in light transmittance.

In the photoreceptor of the present invention, an intermediate layer (33) can be provided between the conductive support (31) and the charge generation layer (35). The intermediate layer (33) generally has a resin as a main component, but these resins are resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. It is desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. However, when the charge generation layer is dispersed in the form of dots as shown in the present invention, the intermediate layer contains a filler and is porous in order to improve the uniformity of size of the charge generation dots to be formed and to prevent bleeding. It preferably has a quality structure.
Further, fine powder pigments of metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the intermediate layer in order to prevent moire and reduce residual potential. These intermediate layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. Furthermore, various dispersing agents can be added. In addition, in the intermediate layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used satisfactorily. However, the unevenness of the charge generation layer is likely to cause unevenness in the image, particularly non-uniformity of the halftone density. For this reason, the intermediate layer is porous in the micron order so that the coating solution does not bleed when the substrate adheres. Such an intermediate layer is desirable. The thickness of the intermediate layer is suitably from 0 to 5 μm.
In the photoreceptor of the present invention, another intermediate layer can be provided between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a generally used coating method as described above is employed. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

  EXAMPLES Next, although this invention is demonstrated based on an Example, this invention is not limited by these Examples.

Example 1
(Photoreceptor configuration)
Intermediate layer Alcohol-soluble copolymer nylon Amylan CM-8000 (manufactured by Toray Industries, Inc.) (specific gravity 1.1) 11 parts dissolved in 200 parts of methanol, and titanium oxide CR-EL (manufactured by Ishihara Sangyo Co., Ltd.) 100 parts of (specific gravity 4.2) was added and dispersed for 12 hours with a ball mill to obtain an intermediate layer coating solution. At this time, the volume ratio of the pigment to the binder resin is 2.4 / 1. An Al plate was dip-coated on this and dried at 110 ° C. for 20 minutes to provide a 4.0 μm intermediate layer.

Charge generation layer Next, a charge generation layer coating solution having the following formulation was prepared.
10 parts by weight of a trisazo pigment represented by the following structural formula (1) is added to a resin solution obtained by dissolving 4 parts by weight of polyvinyl butyral (BM-2: manufactured by Sekisui Chemical Co., Ltd.) in 150 parts by weight of cyclohexanone, and 72 hours by a ball mill. Dispersion was performed. After the completion of dispersion, 250 parts by weight of cyclohexanone and 200 parts by weight of 2-butanone were added and dispersed for 3 hours to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer in the form of dots under the following conditions and dried at 120 ° C. for 20 minutes to form a charge generation layer (both ends 10 mm uncoated portion).

Although some unevenness was observed due to bleeding and spreading of the coating solution, the coating solution was satisfactorily coated without any roughness or unevenness of the coating film. Moreover, since the coating width was controlled, the uncoated part was not wiped off, and the defect due to wiping (thickening of the coating film thickness at the end, splashing at the time of wiping) was good. The amount of coating solution used was about 0.5 ml.
The particle diameter of the charge generation material after dispersion was 0.07 μm. The particle size was measured by centrifugal sedimentation using CAPA-700 manufactured by Horiba.
In the present invention, the coating was performed by modifying a commercially available Seiko Electronics Industry IP-4000 A0 printer (compatible with oil-based pigment ink). A piezo type recording head was used. The ink in the ink cartridge can be replaced. In addition, the aluminum drum was remodeled so that it could be rotated at the ink adhering part and paper position. In addition, coating by the ink jet method can be controlled from a personal computer. The coating width, liquid discharge amount (which changes the size of the dots), and dot spacing were controlled by a personal computer.

Charge Transport Layer Next, a charge transport layer coating liquid having the following structural formula (2) formulation was prepared.

  7 parts by weight of the charge transport material represented by the structural formula (2) and 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 50,000) were dissolved in 100 parts by weight of tetrahydrofuran to prepare a charge transport layer coating solution. This coating solution was dip-coated on the charge generation layer, dried at 130 ° C. for 20 minutes, and a charge transport layer having a thickness of 28 μm was applied to produce the photoreceptor of the example.

In the above, the occupation area ratio (charge generation area area ratio) of the CGL dot portion is set to 100% (ordinary photoconductor not forming CGL in a dot shape) to 60% (area where solid ID can be secured from the above simulation result) Trial manufacture of the photoconductive drum was performed in the range up to the above, and image output was performed using the obtained photoconductor to evaluate the image quality. Evaluation was performed in an environment of 23 ° C. and 50% RH.
As for image output, paying attention to two items of “good reproduction of fine lines” and “stable density change in highlight portion”, the following image output experiments were performed respectively. First, “good reproduction of fine lines” was evaluated visually using an image pattern with 400 lines shown in FIG. 5 using an image output experimental machine with a resolution of 1200 dpi described below. The case where a 400-line line image was reproduced was marked as ◯, and the case where a 400-line line image was not reproduced was marked as x. Whether or not the 400-line line image is set as a criterion for determination is based on the outline of the character part (not to become a rattling outline) and the color of the character when a low-contrast character / color character is printed with a printer. This is set as a substitute characteristic for reproducing both the reproducibility (the target color can be reproduced) and the like.

Next, with respect to “stable density change in the highlight portion”, an 8-bit Tiff image data including patches of 0 to 256 gradations (15 mm square) is used by using an image output experimental machine with a resolution of 1200 dpi described below. On the other hand, image data for output (data after pseudo halftone processing) prepared in advance with dither processing (screen screen number of about 170 lines, screen angle 45 degrees, line screen type, quantization number 2 bits, resolution 1200 dpi) is prepared in advance. In addition, image output is performed using the output image data. The evaluation of the output image was performed using the result of measuring the reflection density (ID value) of the highlight portion (data 0 to 32) with a spectral reflection densitometer (model 938 manufactured by X-Rite). A linear equation is approximated with respect to the relationship between the reflection density value and the input data value, and a case where the value of R ² is 0.95 or more is evaluated as ◯, and a case where the value of R ² is less than 0.95. X. The condition that the R ² value of linear approximation is 0.95 or more in the highlight portion (data 0 to 32) set as the determination criterion here is an abnormal image called a pseudo contour in a gradation image. This is set as a substitute characteristic to reproduce well without occurrence.

  Next, an experimental machine used for image output will be described. This experimental machine is an experimental machine modified on the basis of Ricoh's Ipsio Color 5100, and is mainly a modified writing unit. In this experimental machine, a four-channel LD array in which four light emitting points (laser diodes) are formed in a line on one chip is used as an LD element. Thereby, a resolution of 1200 dpi was realized. In this experimental machine, the optical element and the aperture are adjusted so that the beam diameter is 50 (main scanning direction) × 65 (sub-scanning direction) μm on the photosensitive member position. The amount of the stationary beam of the laser beam is adjusted and set by measurement using the above-described optical power meter.

Next, an image output experiment and results thereof will be described. The prototype photoconductor used in the experiment was prepared by the method described above (photoreceptor configuration) (CGM is a trisazo pigment: the above structural formula (1)). At this time, a trial photoconductor drum was manufactured in which the occupation area of the charge generation layer was changed in the range of 100 to 60% at 1200 dpi while adjusting various discharge conditions of the coating liquid of the ink jet printer.
The occupied area was calculated by photographing the photoconductor with a digital camera using a ZEISS optical microscope and subjecting the obtained data to image processing.
Using the photoconductor drum produced in this way, the image output is performed while changing the amount of the stationary beam of the laser, and the above two items (“400 line line image reproduction”, “Highlight portion are expressed by a linear expression) Tables 1 and 2 below show the results of the evaluation of the approximation and the R ² value of 0.95 or more.

  From the results of Tables 1 and 2, when the occupation area ratio of the charge generation region is 90% or less, the improvement to the “problem to be solved by the invention” as described in the section of the prior art is improved. It turns out that it is possible. Further, when the occupation area ratio of the charge generation region is not less than a certain relationship (the above formula (1)), solid ID = 1.4 or more can be ensured, and good image quality can be realized. .

  Next, the results of outputting a comprehensive test chart including image quality elements such as a highlight portion, a low-contrast character portion, and a solid portion using some of the conditions evaluated above are shown in Table 3. is there.

  In Tables 1 and 2, it can be seen that high-quality images can be obtained even in the output results of the comprehensive test chart under the conditions where good results can be obtained.

Example 2
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer coating solution was changed to the following composition in Example 1 and evaluated in the same manner as in Example 1.
Acrylic resin Acrydic A-460-60
Solid content 60% [manufactured by Dainippon Ink Chemical Co., Ltd.] 15 parts by weight melamine resin Super Becamine L-121-60 10 parts by weight solid content 60% [manufactured by Dainippon Ink Chemical Co., Ltd.]
Methyl ethyl ketone 80 parts by weight Titanium oxide powder CR-EL 49 parts by weight [Ishihara Sangyo Co., Ltd.]
Since the specific gravity of titanium oxide is 4.2 and the specific gravity of the binder resin is 1.3, the volume ratio of pigment (P) / binder resin (R) is 1.0 / 1.
The evaluation results are shown in Tables 4 and 5 below.
The overall test chart showed the same results in Table 3.

Example 3
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer coating solution was changed to the following composition in Example 1 and evaluated in the same manner as in Example 1.
Zinc oxide (E017, manufactured by Teika): 41 parts by mass, curing agent (blocked isocyanate Sumijour 3175, manufactured by Sumitomo Bayern Urethane): 12 parts by mass, butyral resin BM-1 (manufactured by Sekisui Chemical Co., Ltd.): 6 Part by mass, 52 parts by mass of methyl ethyl ketone, Silicone Ball Tospearl 120 (manufactured by Toshiba Silicone): 3 parts by mass, and silicone oil SH29PA as a leveling agent (manufactured by Toray Dow Corning Silicone): 100 ppm are mixed, and batch Dispersion was carried out for 10 hours in an expression mill to obtain an intermediate layer coating solution.
The evaluation results are shown in Tables 6 and 7 below.
The overall test chart showed the same results in Table 3.

Example 4
In Example 1, the thickness of the charge transport layer was set to 25 μm, and a protective layer coating solution having the following composition was applied on the charge transport layer by the ring coating method, and the same procedure as in Example 1 was performed. An electrophotographic photosensitive member was prepared, and after running 80,000 sheets with IpsioColor7500, evaluation was performed in the same manner as in Example 1.
(Protective layer coating solution)
Methyltrimethoxysilane 150 g, phenyltrimethoxysilane 30 g, dihydroxymethyltriphenylamine 75 g, 2-propanol 225 g, 2% acetic acid 106 g, colloidal silica (30% methanol solution) 106 g, triacetylacetonatoaluminum 4 g are mixed and protected A coating solution for the layer was prepared. This coating solution was applied onto the charge transport layer and cured by heating at 110 ° C. for 1 hour to form a protective layer having a dry film thickness of 3 μm.

Example 5
In Example 1, the thickness of the charge transport layer was set to 25 μm, and a protective layer coating solution having the following composition was applied on the charge transport layer by a spray coating method, and the same procedure as in Example 1 was performed. An electrophotographic photosensitive member was prepared, and evaluation was performed in the same manner as in Example 1 after running 50,000 sheets with IpsioColor7500.
(Protective layer coating solution)
Trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure 10 parts trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku)
10 parts of a radically polymerizable compound of the following structural formula (3) having a bifunctional charge transporting structure

Photopolymerization initiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts The above coating solution is spray-coated on the charge transport layer and naturally dried for 20 minutes, and then a metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 500 mW / cm ² , irradiation time: 60 seconds The coating film was cured by light irradiation under the conditions of Further, drying was performed at 130 ° C. for 20 minutes to form a 3.0 μm protective layer.

Example 6
In Example 4, the evaluation was performed in the same manner as in Example 4 except that the electrophotographic photosensitive member of Example 1 was used.

Comparative Example 1
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer was provided as described below in Example 1, and the characteristics after running were evaluated in the same manner as in Example 4.
Intermediate layer An intermediate layer coating solution having the following formulation was prepared.
(Intermediate layer coating solution)
Polyamide resin (CM8000, manufactured by Toray Industries, Inc.) 2 parts Methanol 58 parts n-Butanol 40 parts This coating solution is dip-coated on an aluminum drum having a diameter of 30 mm and a length of 340 mm, dried at 120 ° C. for 20 minutes, and a film thickness of 0 An intermediate layer of 3 μm was prepared.
The results of evaluating the highlight portion are shown in Tables 8 to 11 below.

  From the results of Tables 8 to 11, by using the intermediate layer shown in the present invention, fine line reproducibility and contrast become better, and by using a cross-linked surface layer as the surface layer, fine line reproducibility over time It can be seen that high image quality such as contrast is maintained.

FIG. 6 is a diagram showing that a carrier diameter is larger than a beam spot diameter corresponding to one dot and enters an adjacent image dot region in a conventional laminated photoreceptor. In the exposure beam energy distribution, it is a diagram showing the case of 600 dpi and a beam diameter of 68.9 μm. FIG. 6 is a diagram showing a relationship between a charge generation area area ratio and a toner adhesion amount in the present invention. FIG. 5 is a diagram showing a relationship between a charge generation region area ratio (DM ratio) satisfying a toner adhesion amount M ≧ 0.45 mg / cm ² and quantum efficiency * Power in the present invention. It is explanatory drawing (at the time of resolution 1200 dpi) of a 400 line image pattern. 1 is a configuration diagram of an electrophotographic photoreceptor in the present invention. 3 is another structural drawing of the electrophotographic photosensitive member in the present invention.

Explanation of symbols

31 Conductive Support 33 Intermediate Layer 35 Charge Generation Layer 37 Charge Transport Layer 39 Protective Layer

Claims (11)

  In an electrophotographic photosensitive member comprising an intermediate layer, a charge generation layer, and a surface layer containing a charge transport material on a conductive support, the intermediate layer mainly comprises a metal oxide and a binder resin. Furthermore, the charge generation layer is formed by dispersing minute charge generation regions containing a charge generation material in the form of dots. The charge generation layer has an occupation area ratio of the charge generation region dispersed in the dot form of 90% or less and an occupation area ratio (X) represented by the following formula (1): The electrophotographic photosensitive member according to claim 1.
η × J ≧ 0.01 × EXP (− (X−60) / 10) +0.002 (1)
(Η represents quantum efficiency, and J represents exposure beam energy (J / m ² ).)   The electrophotographic photosensitive member according to claim 1, wherein a pitch of the dots is equal to a resolution of the image forming apparatus.   The electrophotographic photosensitive member according to claim 1, wherein the surface layer is formed using at least one kind of a crosslinkable compound.   The electrophotographic photoreceptor according to claim 4, wherein the crosslinkable compound is a charge transporting compound containing a nitrogen atom in the structure.   The surface layer contains at least one of an organosilicon compound having a hydroxyl group or a hydrolyzable group and a condensate thereof, and a siloxane resin obtained by reacting a charge transporting compound having a reactive group. The electrophotographic photosensitive member according to claim 4, wherein:   7. The electrophotographic photosensitive member according to claim 6, wherein the surface layer comprises at least a cross-linked layer obtained by curing a radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure.   The functional group of the radical polymerizable monomer having no charge transporting structure and / or the radical polymerizable compound having the charge transporting structure used for the surface layer is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member according to claim 7.   9. The electrophotographic photosensitive member according to claim 1, wherein an average particle size of the charge generation material contained in the charge generation region is 0.2 μm or less.   10. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the charge generation region is formed by ejecting a charge generation layer coating liquid by an ink jet method. A method for producing a photographic photoreceptor. The method for producing an electrophotographic photosensitive member according to claim 10, wherein the ink jet method is a piezo method.

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