JP4541932B2 - Image forming method, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to an image forming method that achieves both high image quality and high stability and realizes a long life, and an image forming apparatus and a process cartridge that form an image by the method.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light has a remarkable improvement in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. Furthermore, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing. Against this background, there is a strong demand for higher image quality of the above-mentioned printers and copiers, and with the rapid spread of high-speed full-color image forming apparatuses in recent years, the opportunity to output not only characters but also images has increased remarkably. Accordingly, higher resolution and higher definition are demanded.

  In order to realize such high image quality, it is necessary to make the electrostatic latent image formed by performing optical writing on the electrostatic latent image carrier dense. That is, it is important to form an electrostatic latent image with smaller dots than before. On the other hand, the electrostatic latent image obtained by exposing the electrostatic latent image carrier to the electrostatic latent image carrier is inevitably deteriorated by subsequent development, transfer and fixing processes. It is important for high image quality to reproduce the electrostatic latent image faithfully to the original, and the effect for high image quality is also increased.

  Conventional techniques for reducing the beam diameter of a writing light source for forming an electrostatic latent image can be broadly classified into two. one. This is a technique that uses laser light of short wavelength oscillation, and is a method of using a writing light source having an oscillation wavelength of 450 nm or less that oscillates purple to blue. The other is a technique that optically narrows the beam diameter of light emitted from a light source using a conventionally used light source such as a semiconductor laser.

The former is a technology that is expected more and more in the future as the oscillation light source of 450 nm or less progresses. It is thought to occur. For example, most of the charge transport materials used in the charge transport layer that have been used so far have a structure in which the π-conjugated system is expanded in order to improve transport properties, and the material itself exhibits a yellow color. In addition, it is in the absorption region with respect to the writing light wavelength by the short wavelength light source. For this reason, the charge transport material blocks the writing light, and the photosensitivity of the electrostatic latent image carrier is significantly reduced. In addition, the charge transport material itself absorbs light, whereby the charge transport material is promoted to deteriorate via an excited state, and the function of the electrostatic latent image carrier itself is deteriorated. Therefore, a charge transport material that transmits light having a wavelength shorter than 450 nm is required.
Furthermore, there are problems associated with charge generating materials. Light having a wavelength shorter than 450 nm has a high energy as described above, and is higher than the energy necessary for the generation of optical carriers, and therefore has surplus energy. Conventional electrostatic latent image carriers generally have a function-separated type photosensitive layer structure in which a charge transport layer containing a charge transport material is laminated on a charge generation layer containing a charge generation material. As described above, most of the charge transport materials that have been used in the past have a yellow color. Therefore, light having a wavelength shorter than 450 nm (for example, ultraviolet light emitted from a charging member, ultraviolet light emitted from a fluorescent lamp, etc.) is charged. Since it is absorbed by the transport layer and does not pass through the charge generation layer, deterioration of the charge generation layer (charge generation material) due to short wavelength light has not been a problem. However, when a charge transport material that transmits light having a wavelength shorter than 450 nm is used for the charge transport layer, the charge generation layer is directly affected.

FIG. 1 shows a schematic diagram of a photocarrier generation mechanism using an organic charge generating material. As shown in FIG. 1, the generation of photocarriers in the organic charge generating substance is performed through the lowest excited singlet state (S ₁ ). The charge generation material existing in the ground state (S ₀ ) is excited to an excited state by light absorption. At this time, the height (potential) to be launched energetically differs depending on the light energy (that is, wavelength). The charge generating material that has obtained an energy higher than the energy difference between S ₀ and S ₁ is once launched to a higher excited state (S ^* ), and is normally thermally relaxed to the S ₁ state. Is generated. At this time, higher energy than the energy level of the S ₁ (the energy difference between the S ₁ and S ^*) is excess energy, may also be all used for other reactions without being relaxed thermally. The excited state of the organic substance is in a very active state, and is thermally relaxed internally and settles into the S ₁ state. In addition to reacting with other substances using the surplus energy (oxidation, decomposition, etc.), It also binds between the same molecules and changes the molecular structure (isomerization, etc.). Thus, considering only the reaction process of photocarrier generation, the surplus energy promotes the deterioration of the material, so that high chemical stability is required for the charge generation material.
From the above, the electrostatic latent image carrier used in an image forming apparatus using a short-wavelength laser beam as an exposure light source has a long life and a high lifetime of the main materials (charge generating substance, charge transporting substance) constituting it. Stabilization is required.

On the other hand, the latter technique of optically reducing the beam diameter requires the development of an optical system (lens, mirror, etc.). Recently, an LD light source generally used in digital image forming apparatuses has been used so far. Therefore, the beam diameter can be reduced to 50 μm or less (see Patent Document 1). The development of such a writing technique makes it possible to develop an existing material technique in developing an electrostatic latent image carrier, which is very advantageous in terms of cost.
With the development of the optical system in the image forming apparatus as described above, it has become possible to make the beam diameter much smaller than the conventional one (approximately 60 to 70 μm or more). As a result, it has become possible to reduce the dot diameter of the electrostatic latent image formed on the electrostatic latent image carrier. However, the formation of the electrostatic latent image is performed by canceling out the charge applied to the electrostatic latent image carrier by the reverse charge generated by writing. Dots are not formed, and a device for utilizing the small-diameter beam forming technique is also required.
That is, although the beam diameter irradiated on the charge generation layer by writing with a small-diameter beam is certainly small, optical carriers are generated at a high density in a narrow area because of the high-density writing. The photocarriers are generated as a pair of holes and electrons, but move to the surface of the electrostatic latent image carrier and the electrode (conductive support) by the electric field applied to the electrostatic latent image carrier. At this time, the moving direction is determined by the polarity applied to the surface of the electrostatic latent image carrier. However, in the case of the function-separated organic laminated electrostatic latent image carrier, the negative polarity is generally applied to the surface. , Holes travel to the surface and electrons travel to the electrode.

  It is known that when charges of the same polarity are close to each other, Coulomb repulsion is caused by the mutual charges, and the electrostatic latent image carrier is no exception. In particular, when high-density writing is performed as described above, photocarrier generation is performed at high density. Therefore, if charges are not moved smoothly, recombination by holes and electrons (results in a decrease in carrier generation efficiency) In addition to this, a problem arises in that the dots spread when moving through the charge transport layer. As a result, as shown in FIG. 2, the dot diameter of the electrostatic latent image formed on the surface of the electrostatic latent image carrier is increased even if the writing is made with a small-diameter beam.

  FIG. 3 shows the relationship between the electric field intensity applied to the electrostatic latent image carrier and the dots developed from the electrostatic latent image (writing is performed at 1200 dpi). FIG. 3 shows a toner image when developed using a toner having a sufficiently small particle diameter. However, when the electric field strength is low, the dots are large and blurred. This is because carriers generated in the charge generation layer spread due to Coulomb repulsion when crossing the charge transport layer, and the potential contrast corresponding to the writing portion and the non-writing portion on the surface of the electrostatic latent image carrier was not sufficiently obtained. It shows that. Therefore, when forming minute dots by writing such a small diameter beam, the electric field strength applied to the electrostatic latent image carrier must be set high. According to the study by the present inventors, an electric field strength of 30 V / μm or more is required for an ordinary electrostatic latent image carrier having a charge transport layer thickness of about 30 μm or less.

  The electric field strength of 30 V / μm or higher is set higher than the normal applied electric field strength, and increases the stress on the electrostatic latent image carrier. FIG. 4 shows the relationship between the electric field strength applied to the electrostatic latent image carrier and the background stain. The scumming rank in the figure indicates the level of scumming, and the greater the number, the better the level of scumming. As can be seen from the figure, an increase in the electric field strength promotes the occurrence of background staining, and the background contamination and dot reproducibility (formation of minute dots) have a trade-off relationship with respect to the field strength.

  Conventionally, in order to avoid scumming, a system in which the electric field strength of the electrostatic latent image carrier is used at 30 V / μm or less and the reproduction of small-diameter dots is somewhat sacrificed has been used. For example, in Patent Document 2, there is a description that the electric field strength of the electrostatic latent image carrier is used at 12 to 40 V / μm in order to achieve both reproducibility of background stains and fine lines.

  However, when the resolution of the writing light is increased, the writing dots cannot be developed with good reproducibility unless this lower limit is set higher. Further, regarding the background contamination of the electrostatic latent image carrier, the upper limit value of the electric field strength varies depending on the material (mainly charge generation material) constituting the electrostatic latent image carrier. A titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the CuKα ray (wavelength 1.542 mm) is very sensitive. It has a disadvantage that it is weak against dirt, and as described above, it is practically used only at an electric field strength of 30 V / μm or less.

  A titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the CuKα ray (wavelength 1.542 mm) is a static having high sensitivity and high speed response. Although it is widely used as a charge generating material for an electrostatic latent image carrier, the photocarrier generation efficiency (capability) of this titanyl phthalocyanine crystal depends on the electric field strength, and the carrier generation efficiency decreases extremely as the electric field decreases. . For this reason, in an actual system, it is the actual situation that the advantage of specific high sensitivity in the titanyl phthalocyanine crystal is not fully utilized. Such a problem is a phenomenon that does not cause much problem with low-resolution (400 dpi or less) writing light, but it appears prominently in recent high-resolution writing (600 dpi or more, finer writing is 1200 dpi or more). is there.

  In addition, this titanyl phthalocyanine crystal has a problem that it is low in stability and easily undergoes a crystal transition with respect to mechanical stress such as dispersion and thermal stress. The sensitivity is very low compared to the crystal type, and when a part of the crystal undergoes crystal transition, sufficient photocarriers cannot be generated. Furthermore, the repeated use of the electrostatic latent image carrier tends to cause a decrease in chargeability and a problem that an afterimage or a ghost image is likely to occur. In addition, there is a problem inherent in negative / positive development, in which abnormal images called background images are likely to occur.

In addition, writing with a small-diameter beam is intended for high-density writing. However, as described later, there is a problem of reciprocity failure of the electrostatic latent image carrier sensitivity at high density, The writing (electrostatic latent image) dot outline may be blurred.
Furthermore, when forming a small-diameter dot using a small-diameter beam as described above, if the charge generation layer does not have a sufficiently homogeneous structure, the outline of the minute dot will not be clear, and the advantages of the small-diameter beam are not necessarily obtained. Thus, homogenization of the charge generation layer (that is, miniaturization of the charge generation material particles) has not been considered.

  From the above, in an image forming method in which minute dots are formed using a writing light source having a beam diameter of 50 μm or less, (1) since high-density writing is performed per unit area, The latent image carrier (charge generating material) has a high photocarrier generation capability. (2) Sufficient electric field strength applied to the electrostatic latent image carrier to prevent the charge from diffusing due to Coulomb repulsion when the charge is transferred. (3) Must be an electrostatic latent image carrier with high anti-smudge property when high electric field strength is applied, (4) Sufficient for writing small-diameter beams In order to obtain uniform homogeneity, the charge generation material contained in the charge generation layer needs to be sufficiently small.

  The above problems are all related to the photosensitive layer (charge generation layer) except for the transparency of the charge transport material, and the development of an electrostatic latent image carrier for image forming apparatus intended to form micro dots by high density writing. Is dependent on the development of charge generating materials.

As described above, in order to realize high image quality, it is necessary to improve many image quality deterioration factors in the process or the electrostatic latent image carrier, but that is not sufficient. For example, even if a high-quality image is obtained in the initial stage, if the image quality deteriorates immediately after repeated use, this does not mean that the image quality has been improved, and the image forming apparatus is required to have a higher image quality. At the same time, there is a strong demand for high stabilization that can maintain the image quality even after repeated use.
Furthermore, with the rapid spread of image forming apparatuses capable of full-color image output, the demand for speeding up and downsizing of the apparatus is increasing, and it is even more important to increase the life of the electrostatic latent image carrier. It has become. In particular, in order to increase the speed of full-color image output, an electrostatic latent image carrier and a plurality of image forming elements such as charging, exposure, development, cleaning, and static elimination are arranged and processed in parallel. Although a color image forming apparatus is effective and has become the mainstream at present, since a plurality of electrostatic latent image carriers and image forming elements are provided, downsizing of the image forming apparatus is a major issue. In order to reduce the size of the image forming apparatus, it is particularly necessary to reduce the diameter of the electrostatic latent image carrier. In this case, the life of the electrostatic latent image carrier is sacrificed. It is necessary to mount an electrostatic latent image carrier that has a high image quality and that can maintain a stable image quality even when used for a long time.

  Factors that determine the life of an electrostatic latent image carrier are roughly divided into two, one is electrostatic fatigue, and one is wear of the surface layer. Both are major problems for the current mainstream organic electrostatic latent image carrier. The former is derived from changes in the surface potential (charge potential and exposure portion potential) of the electrostatic latent image carrier when processes necessary for image formation such as charging and exposure are used repeatedly, and organic materials are generally used. In a latent electrostatic image bearing member, a decrease in charging potential or an increase in exposure portion potential (sometimes referred to as residual potential) is the biggest problem. If the charge decrease or the exposure portion potential increase becomes noticeable due to fatigue of the electrostatic latent image carrier, the background contamination may increase or the image density may decrease. On the other hand, the latter is a phenomenon in which a layer located on the outermost surface constituting the electrostatic latent image carrier is mechanically worn by sliding of a cleaning member or the like. If the film thickness of the surface layer of the electrostatic latent image carrier decreases due to this wear, scratches on the surface, an increase in electric field strength due to a decrease in the film thickness of the photosensitive layer, acceleration of electrostatic fatigue, etc. may occur. There is a risk that scratches on the surface of the carrier appear as a direct abnormal image, or that the electric field strength increases due to wear of the electrostatic latent image carrier, resulting in an increase in background contamination. Therefore, in order to improve the life of the electrostatic latent image carrier, it is necessary to solve the above two problems at the same time. In particular, most of the image forming apparatuses currently in widespread use are based on negative / positive development. For this reason, it can be said that the background problem is the soiling where countless black spots occur on the background.

  Causes of scumming are dirt and defects on the conductive support, electrical insulation breakdown of the photosensitive layer, carrier (charge) injection from the support, increased dark decay of the electrostatic latent image carrier, and in the photosensitive layer. For example, heat carrier generation. Of these, the contamination and defects of the support can be dealt with by eliminating such support before applying the photosensitive layer, and is not the essence of the cause. Therefore, improving the voltage resistance of the electrostatic latent image bearing member, the charge injection property from the support, and the reduction in electrostatic fatigue is considered to be the fundamental solution to this problem.

Examples of conventional techniques relating to the injection of electric charges from a conductive support, which is one of the causes of scumming, include, for example, a cellulose nitrate-based resin intermediate layer (see Patent Document 3) and a nylon-based resin intermediate layer (see Patent Document 4). ), A technique for providing an undercoat layer or an intermediate layer between a photosensitive support and a photosensitive layer, such as a maleic acid resin intermediate layer (see Patent Document 5) and a polyvinyl alcohol resin intermediate layer (see Patent Document 6). ing.
However, since these single layers and the intermediate layer of the resin alone have high electric resistance, the residual potential is increased, and the image density is lowered in negative / positive development. In addition, since it exhibits ionic conductivity due to impurities and the like, the electrical resistance of the intermediate layer is particularly high in a low temperature and low humidity environment, so the residual potential is significantly increased, and the electrical resistance of the intermediate layer is high in a high temperature and high humidity environment. There was a tendency to decrease and to easily cause soiling. For this reason, in order to reduce the residual potential, it is necessary to reduce the thickness of the intermediate layer, and it has been a fact that sufficient suppression of background contamination has not been realized.

In order to solve these problems, as a technique for controlling the electric resistance of the intermediate layer, for example, an intermediate layer in which carbon or a chalcogen-based material is dispersed in a curable resin (see Patent Document 7), a quaternary ammonium salt is added. A thermal polymer intermediate layer using an isocyanate-based curing agent (see Patent Document 8), a resin intermediate layer to which a resistance modifier is added (see Patent Document 9), and a resin intermediate layer to which an organometallic compound is added (see Patent Document 10) A method of adding a conductive additive such as) to the bulk of the intermediate layer has been proposed.
However, these resin intermediate layers alone tend to increase scumming even when the residual potential is reduced, and in recent image forming apparatuses using coherent light such as laser light, moire images are displayed. It has the problem that it occurs.

Further, for the purpose of simultaneously controlling the moire prevention and the electric resistance of the intermediate layer, for example, a resin intermediate layer in which an oxide of aluminum or tin is dispersed (see Patent Document 11), a resin intermediate layer in which conductive particles are dispersed (Patent Document) 12), an intermediate layer in which magnetite is dispersed (see Patent Document 13), a resin intermediate layer in which titanium oxide and tin oxide are dispersed (see Patent Document 14), borides such as calcium, magnesium, and aluminum, nitrides, fluorides In addition, an electrostatic latent image carrier in which a filler is contained in an intermediate layer such as a resin intermediate layer (see Patent Documents 15 to 20) in which oxide powder is dispersed has been proposed.
However, in the intermediate layer in which the filler is dispersed, it is preferable to increase the filler amount to reduce the residual potential, and to reduce the soiling, it is preferable to reduce the filler amount. It was difficult to achieve both. In addition, when the resin content decreases, the adhesion to the conductive support decreases, and there is a problem that peeling easily occurs. In particular, the conductive support is a flexible belt-like electrostatic latent image carrier. So the effect was fatal.

In order to solve such problems, a concept of stacking intermediate layers has been proposed. The structure of lamination is roughly classified into two types. One is, as shown in FIG. 5, a resin layer 2 in which filler is dispersed on a conductive support 1, a resin layer 3 in which filler is not dispersed, and a photosensitive layer 4. As shown in FIG. 6, the other is one in which a resin layer 3 in which filler is not dispersed, a resin layer 2 in which filler is dispersed, and a photosensitive layer 4 are sequentially provided on a conductive support 1. It is.
To elaborate the former configuration, in order to conceal the defects of the support as described above, a conductive filler dispersion layer in which a low-resistance filler is dispersed is provided on the conductive support, and the resin layer is provided thereon. (See Patent Documents 21 to 29).
However, this configuration can prevent the occurrence of moire by the filler dispersion layer containing the conductive filler, and since the resin layer is provided on the filler dispersion layer, the effect of suppressing soiling can be obtained. However, since it is only the resin layer that suppresses carrier injection from the conductive support, as in the case where the above resin layer is used alone, if the film thickness is increased, a significant increase in residual potential is obtained. If the film thickness is reduced, an increase in background contamination will be caused, and it is not satisfactory in realizing both of them. In addition, an insulating resin layer is laminated on the filler dispersion layer, and the filler dispersion layer needs to be thick (10 μm or more) in order to conceal defects in the conductive support. Even if the resistance of the filler contained in the layer is increased to suppress the soiling, it is difficult because the influence of the residual potential is remarkably increased.
In addition, an electrostatic latent image carrier in which a conductive layer, an intermediate layer, and a photosensitive layer containing a titanyl phthalocyanine crystal are stacked has been proposed (see Patent Documents 30 to 32).
However, it is difficult to sufficiently suppress the influence of soiling by simply laminating the conductive layer and the intermediate layer. This is because, in addition to the above reasons, the titanyl phthalocyanine used in the photosensitive layer also contains a soiling factor.

On the other hand, as the latter configuration, a resin layer that suppresses carrier injection is provided on a conductive support, and a filler dispersion layer containing a filler is provided thereon (see Patent Documents 33 and 34). In this case, the carrier injection can be suppressed by the resin layer, but the filler dispersion layer containing the filler laminated thereon has little influence on the residual potential even if it does not contain the conductive filler. The suppression effect is also increased, and it is more effective than the former configuration in achieving both residual potential and soiling.
However, the structure in which a plurality of subbing layers are laminated and separated in this way shows high effectiveness in achieving both prevention of moire, suppression of background contamination, and reduction of residual potential, but the resin layer is made thin. Depending on the resin used there, there is a tendency that the soil dependency and the residual potential are highly dependent on humidity, and that the dependency on the film thickness is increased, and the stability is not necessarily high. Further, the cause of soiling is not only the injection of charges (holes) from the conductive support to the photosensitive layer, but also the influence of thermal carrier generation in the photosensitive layer cannot be ignored. For this reason, unless the charge generation material used in the charge generation layer and the particle state thereof are controlled, the occurrence of scumming in repeated use cannot be completely controlled.

For the problem of speeding up, an electrostatic latent image carrier having high sensitivity and high speed response has been used. Usually, an LED of 780 nm LD or near 760 nm is used as a light source, and as a corresponding electrostatic latent image carrier (charge generation material), a diffraction peak (± 0) with respect to CuKα rays (wavelength 1.542Å) is used. .2 °), it is known to use titanyl phthalocyanine crystals such as a titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° (see Patent Documents 35 to 42). This specific crystal type has a very high carrier generation function and can be effectively used as a charge generation material for an electrostatic latent image carrier for a high-speed image forming apparatus. However, this crystal type has a problem that its stability as a crystal is low, and it is easy to undergo a crystal transition against mechanical stress such as dispersion, and thermal stress. Compared to the above, the sensitivity is very low, and when a part of the crystal undergoes crystal transition, a sufficient photocarrier generation function cannot be exhibited. In addition, when the electrostatic latent image carrier is used repeatedly, there is a problem that an abnormal image called a scumming image, which is a problem inherent to negative / positive development, is likely to occur.
In addition, conventional titanyl phthalocyanine has strong agglomeration properties, and when it is used in the charge generation layer, even if the injection of charge from the undercoat layer is suppressed, it is charged in the local area where aggregates and coarse particles exist. Decrease and increase of dark decay occur, and it becomes manifest as soil. Further, the purity of titanyl phthalocyanine is greatly affected, and the soil resistance is significantly lowered by causing a significant decrease in charge due to the inclusion of impurities or an increase in dark decay due to fatigue (see Patent Documents 35 to 42). ). Therefore, it is necessary to eliminate the cause of soiling by controlling the dispersibility and crystal type of the titanyl phthalocyanine crystal used in the charge generation layer.

  In the prior art, when the soiling is suppressed, the residual potential increase and the environmental dependency are remarkably increased, and when the residual potential increase is suppressed, the soiling suppression effect becomes insufficient, and both of them are not realized. It was. As described above, scumming includes not only the influence of charge injection from the conductive support but also many factors such as the influence of coarse particles of titanyl phthalocyanine and impurities contained in the photosensitive layer or the charge generation layer. However, another important factor that greatly affects the background contamination is an increase in electric field strength due to a decrease in the film thickness of the electrostatic latent image carrier.

  Therefore, the charge transport layer or the protective layer formed on the outermost surface of the electrostatic latent image carrier has been devised to improve the wear resistance. Techniques for improving the abrasion resistance of the photosensitive layer include (i) using a curable binder in the crosslinkable charge transport layer (see Patent Document 43), and (ii) using a polymer charge transport material ( Patent Document 44), (iii) A crosslinked charge transport layer in which an inorganic filler is dispersed (see Patent Document 45), and the like. As described above, since the variation with time of the electric field strength can be reduced by increasing the wear resistance of the electrostatic latent image carrier, a high effect can be obtained with respect to the suppression of soiling.

  However, among these technologies, those using the curable binder (i) have a poor residual potential due to poor compatibility with the charge transport material and impurities such as polymerization initiators and unreacted residues. There is a tendency for image density reduction to occur easily. In addition, the material using the polymer type charge transport material (ii) can sufficiently improve the wear resistance, but sufficiently satisfies the durability required for the organic electrostatic latent image carrier. It hasn't been done yet. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain a high-purity material. Therefore, it is difficult to stabilize electrical characteristics between materials. Furthermore, production problems such as high viscosity of the coating solution may occur. The dispersion of the inorganic filler of (iii) exhibits higher wear resistance than an electrostatic latent image carrier in which a normal low molecular charge transport material is dispersed in an inert polymer. The residual potential increases due to the charge traps present in the image, and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the electrostatic latent image carrier is large, poor cleaning may occur, which may cause toner filming and image flow. These techniques (i), (ii), and (iii) have defects in residual potential, cleaning properties, etc., even if they are effective in suppressing scumming. I haven't fully satisfied.

Furthermore, there is also known an electrostatic latent image carrier containing a polyfunctional acrylate monomer cured product in order to improve the abrasion resistance and scratch resistance of (i) (see Patent Document 46).
However, in this electrostatic latent image carrier, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, the protective layer contains a charge transport material. There is no specific description, and there is a problem of compatibility with the cured product when a low-molecular charge transport material is simply contained in the cross-linked charge transport layer. As a result, precipitation of a low-molecular charge transport material and white turbidity occur, and not only the image density is lowered but also the mechanical strength is lowered due to an increase in the potential of the exposed portion. Furthermore, since this electrostatic latent image carrier specifically reacts with the monomer in a state containing a polymer binder, the three-dimensional network structure does not proceed sufficiently, and the crosslink density becomes dilute. It has not yet reached the point where it is possible to exhibit excellent wear resistance.

As a wear resistance technique for the photosensitive layer related to these, a charge transport layer formed by using a coating solution comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin. It is known to provide (refer patent document 47). This binder resin is thought to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further mitigating the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are roughly classified into those having reactivity with the charge transporting substance and those having no reactivity with the double bond.
However, this electrostatic latent image bearing member is noticeable because it has both wear resistance and good electrical characteristics, but when a binder resin having no reactivity is used, the binder resin, Poor compatibility with the cured product produced by the reaction between the monomer and the charge transporting material, causing layer separation in the cross-linked charge transporting layer, causing scratches and sticking of external additives and paper powder in the toner. There is. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in the electrostatic latent image carrier is bifunctional, and in these respects, it is still not satisfactory in terms of wear resistance. There wasn't. Furthermore, even when a reactive binder is used, the number of cross-linking bonds between molecules is small, although the molecular weight of the cured product is increased, and it is difficult to achieve both the bonding amount of the charge transport material and the cross-linking density. Abrasion was not sufficient.

A photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (see Patent Document 48).
However, this photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress is reduced. In some cases, the cross-linked surface layer tends to crack and peel off when used for a long time. Therefore, it can not be said that the electrostatic latent image bearing member having the crosslinked photosensitive layer in which the charge transporting structure is chemically bonded in the prior art has sufficient comprehensive characteristics at present.

  In this way, scumming is affected not only by the undercoat layer, but also by the charge generation layer and the charge transport layer or protective layer, so that scumming is completely suppressed unless they are improved simultaneously. It is difficult to achieve high durability of the electrostatic latent image carrier. However, in the prior art, there are few examples in which the background contamination is suppressed in all the layers constituting the electrostatic latent image bearing member, and when all the layers are improved at the same time, the increase in the residual potential becomes remarkable. Dirt stains, such as being visible, increasing the dependency of chargeability and residual potential on humidity, increasing the effects of filming and image blurring, and causing image defects due to scratches on the surface of the electrostatic latent image carrier. Other than the above, image quality deterioration factors have increased remarkably, and as a result, the electrostatic latent image carrier has not been made highly durable.

  In addition, the development of an electrostatic latent image carrier has been developed in response to process restrictions (requests) that arise in order to design an image forming apparatus that realizes high-density writing by forming a small-diameter beam by optical system innovation. The situation is not sufficient, and the actual situation is that the development of an electrostatic latent image carrier for realizing stable and repetitive image formation is not sufficient.

  Image forming apparatuses are required to be miniaturized, speeded up, and improved in image quality with rapid progress in full color, and it is essential to extend the life of an electrostatic latent image carrier. In order to achieve both high image quality and high stability and to achieve a long life, it is necessary to improve both the process and the electrostatic latent image carrier to compensate for each other's disadvantages. However, the conventional image forming method, the image forming apparatus and the process cartridge for forming an image by the method are not sufficiently satisfied as a technology capable of achieving both of them, and cannot be said to have a sufficient lifetime. .

JP-A-2002-277801 JP 2001-154379 A JP 47-6341 A JP-A-60-66258 Japanese Patent Laid-Open No. 52-10138 JP 58-105155 A JP 51-65942 A JP 52-82238 A JP-A-55-113045 JP 58-93062 A Japanese Patent Laid-Open No. 58-58556 Japanese Unexamined Patent Publication No. 60-111255 JP 59-17557 A JP-A-60-32054 JP-A 64-68762 JP-A 64-68763 JP-A 64-73352 JP-A 64-73353 JP-A 1-1118848 Japanese Patent Laid-Open No. 1-118849 JP 58-95351 A JP 59-93453 A JP-A-4-170552 JP-A-6-208238 JP-A-6-222600 Japanese Patent Laid-Open No. 8-184979 Japanese Patent Laid-Open No. 9-43886 JP-A-9-190005 JP-A-9-288367 Japanese Patent Application Laid-Open No. 5-100461 JP-A-5-210260 Japanese Patent Laid-Open No. 7-271072 Japanese Patent Laid-Open No. 5-80572 Japanese Patent Laid-Open No. 6-19174 JP 2001-19871 A JP-A-8-110649 JP-A-1-299874 Japanese Patent Laid-Open No. 3-269064 Japanese Patent Laid-Open No. 2-8256 JP-A 64-17066 Japanese Patent Laid-Open No. 11-5919 JP-A-3-255456 JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. In other words, the present invention reduces the side effects caused by using a small diameter beam with a diameter of 50 μm or less as a writing light source, and realizes high image quality by taking advantage of the advantage. To provide an image forming method capable of stably maintaining a high quality image with little image quality, achieving both high image quality and high stability, and realizing a long life, and an image forming apparatus and a process cartridge for forming an image by the method. With the goal.

  In the image forming method using a light source having a beam diameter of 50 μm or less, the present inventors maintain an image quality even when used under a high electric field strength, and form an image with few abnormal images even during repeated use. As a result, the electrostatic latent image carrier to be used has at least a charge blocking layer, a moire preventing layer, and an average primary particle size of 0.25 μm or less on a conductive support. The diffraction value of the Bragg angle 2θ in the error range ± 0.2 ° with respect to the X-ray having a wavelength of 1.542 mm by the CuKα ray has a maximum value at 27.2 °, and further, 7.3 ° and 9.4. Photosensitivity comprising titanyl phthalocyanine crystals having at least maximum values at °, 9.6 °, and 24.0 °, and not exceeding 7.3 and less than 9.4 °, and having no maximum value at 26.3 ° Layers of layers in this order. By using the carrier, maintaining a titanyl phthalocyanine inherent high sensitivity, it has been found to be a high-speed image output with high image quality and high durability.

  In the prior art, it is already known that the resolution is improved by reducing the beam of writing light and reducing the formed dots. In addition, the voltage applied to the electrostatic latent image carrier is increased to increase the electric field strength applied to the electrostatic latent image carrier, and the linearity of the movement of the optical carrier generated inside the electrostatic latent image carrier is increased. It is already known that the diffusion of dots in the electrostatic latent image can be suppressed by performing the above. If these can be combined, a small-diameter dot (group of optical carriers) is formed inside the electrostatic latent image carrier, and the electric lines of force between the electrode (conductive support) and the surface of the electrostatic latent image carrier By suppressing the coulomb repulsion of the optical carrier and moving the optical carrier along the lines of electric force, the shape of the dots written with a small-diameter beam itself is the electrostatic latent image carrier surface potential profile (electrostatic latent image) Dot).

However, an increase in the intensity of the electric field applied to the electrostatic latent image carrier promotes charge injection from the support to the photosensitive layer and generation of thermal carriers inside the photosensitive layer, and consequently promotes the occurrence of scumming. . This phenomenon is generally remarkable when a charge generation material having high photocarrier generation efficiency is used, and the Bragg angle in an error range of ± 0.2 ° with respect to the X-ray having a wavelength of 1.542 mm by the CuKα ray described above. When a titanyl phthalocyanine crystal having a maximum value at 27.2 ° as the diffraction value of 2θ is used, the actual situation is that the electric field strength is used in a region of less than 30 V / μm at most.
As described above, although effective means for controlling the process have been developed, an effective electrostatic latent image carrier that takes advantage of the features has not been developed. In reality, there are still problems that the electrostatic latent image faithful to the writing dots on the electrostatic latent image carrier and the toner development faithful to the electrostatic latent image cannot be developed. .
The present invention reduces the side effects of the electrostatic latent image carrier due to the use of effective means for high image quality, and improves image quality and suppresses the occurrence of abnormal images, thereby repeatedly using high quality images. In this way, a long-life image forming method capable of stable output has been completed.

Means for solving the problems are as follows. That is,
<1> A charging step for charging the surface of the latent electrostatic image bearing member with an electric field strength of 30 V / μm or more obtained from the following formula, and a light source having a beam diameter of 50 μm or less on the latent electrostatic image bearing member. An electrostatic latent image forming step for forming an electrostatic latent image using the toner, a developing step for developing the electrostatic latent image with toner to form a visible image, and transferring the visible image to a recording medium. An image forming method including a transfer step and a fixing step of fixing a transfer image transferred to a recording medium,
The electrostatic latent image carrier is formed by laminating at least a charge blocking layer, a moire preventing layer, and a photosensitive layer in this order on a conductive support,
The charge blocking layer is made of methoxymethylated nylon, and the film thickness is 0.5 μm or more and less than 2.0 μm,
In the photosensitive layer, the average particle diameter of primary particles is 0.25 μm or less, and the diffraction value of Bragg angle 2θ in an error range of ± 0.2 ° with respect to X-ray having a wavelength of 1.542 mm by CuKα ray is 27 A maximum value at .2 °, and at least maximum values at 7.3 °, 9.4 °, 9.6 °, and 24.0 °, and more than 7.3 °, 9.4. A titanyl phthalocyanine crystal having a maximum value of less than 0 ° and 26.3 °,
The titanyl phthalocyanine crystal has a maximum value of at least 7.0 ° to 7.5 ° as a diffraction value of a Bragg angle 2θ in an error range of ± 0.2 ° with respect to an X-ray having a wavelength of 1.542 mm by a CuKα ray. In addition, after crystallization of amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having an average particle diameter of 0.1 μm or less in a primary solvent having a half width of 1 ° or more in an organic solvent in the presence of water, and after crystallization It is an image forming method characterized by being obtained by fractionating and filtering a titanyl phthalocyanine crystal before the average particle diameter of primary particles exceeds 0.25 μm.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)
<2> The image forming method according to <1>, wherein the photosensitive layer is formed by laminating a charge generation layer and a charge transport layer in this order on a moire prevention layer.
< 3 > The image forming method according to any one of <1> to <2>, wherein the charging step is a step of using a scorotron charging member.
< 4 > The moiré-preventing layer contains an inorganic pigment and a binder resin, and the volume ratio of the inorganic pigment to the binder resin is 1/1 to 3/1, according to any one of <1> to < 3 >. This is an image forming method.
< 5 > The image forming method according to < 4 >, wherein the binder resin is a thermosetting resin.
< 6 > The image forming method according to < 5 >, wherein the thermosetting resin is a mixture of an alkyd resin and a melamine resin.
< 7 > The image forming method according to < 6 >, wherein the mixing ratio of the alkyd resin and the melamine resin is 5/5 to 8/2.
< 8 > The image forming method according to any one of < 4 > to < 7 >, wherein the inorganic pigment is titanium oxide.
< 9 > Consisting of two or more kinds of titanium oxides having different average particle diameters, when the average particle diameter of the largest titanium oxide is D1 and the average particle diameter of the smallest titanium oxide is D2, 0.2 <(D2 / D1) The image forming method according to < 8 >, wherein ≦ 0.5.
< 10 > The image forming method according to < 9 >, wherein D2 is 0.05 <D2 <0.2 μm.
<11> greatest titanium oxide T1, smallest titanium oxide is taken as T2, the mixing ratio between T1 and T2, is 0.2 ≦ T2 / (T1 + T2 ) ≦ 0.8 in a weight ratio of < The image forming method according to any one of 9 > to < 10 >.
< 12 > The image forming method according to any one of <1> to < 11 >, wherein the titanyl phthalocyanine crystal does not contain a halide.
< 13 > A titanyl phthalocyanine crystal is obtained by crystallizing amorphous titanyl phthalocyanine or low-crystalline titanyl phthalocyanine, and obtained by an acid paste method, washed with ion-exchanged water, and the pH of ion-exchanged water after washing is The image forming method according to any one of <1> to < 12 >, wherein the specific conductivity is 6 to 8 and the specific conductivity of the ion exchange water is 8 μS / cm or less.
< 14 > The crystallization according to any one of <1> to < 13 >, wherein the amount of the organic solvent used in crystallization is 30 times the amount of amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine by weight ratio. An image forming method.
< 15 > The image forming method according to any one of <1> to < 14 >, wherein the photosensitive layer contains a polycarbonate containing triarylamine in any of a main chain and a side chain.
< 16 > The image forming method according to any one of <1> to < 15 >, wherein a protective layer is provided on the photosensitive layer.
< 17 > The image forming method according to < 16 >, wherein the protective layer contains an inorganic pigment or metal oxide having a specific resistance of 10 ¹⁰ Ω · cm or more.
< 18 > The image forming method according to any one of < 16 > to < 17 >, wherein the protective layer contains a polymer charge transport material.
< 19 > The image forming method according to any one of < 16 > to < 18 >, wherein the protective layer contains a binder resin, and the binder resin has a crosslinked structure.
< 20 > The image forming method according to < 19 >, wherein the crosslinked structure of the binder resin has a charge transport site.
< 21 > The protective layer is formed by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure < The image forming method according to any one of 16 > to < 20 >.
< 22 > The image forming method according to < 21 >, wherein the functional group of the radical polymerizable monomer having three or more functional groups is any one of an acryloyloxy group and a methacryloyloxy group.
< 23 > The image forming method according to any one of < 21 > to < 22 >, wherein the molecular weight of the tri- or higher functional radical polymerizable monomer is 250 times or less the number of functional groups.
< 24 > The image forming method according to any one of < 21 > to < 23 >, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure is an acryloyloxy group or a methacryloyloxy group.
< 25 > The image forming method according to any one of < 21 > to < 24 >, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure is a triamylamine structure.
< 26 > The image according to any one of < 21 > to < 25 >, wherein the radical polymerizable compound having a monofunctional charge transporting structure is at least one of the following structural formulas (1) and (2). It is a forming method.
In the Structural Formula (1) and (2), R ₁ has a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, a substituent Aryl group, cyano group, nitro group, alkoxy group, —COOR ₇ (wherein R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group or a substituent which may have a substituent) Aryl group which may have a group), carbonyl halide group or CONR ₈ R ₉ (wherein R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, or a substituent. Represents an aralkyl group which may be substituted or an aryl group which may have a substituent, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group. The same May be different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3.
< 27 > The image forming method according to any one of < 21 > to < 26 >, wherein the radical polymerizable compound having a monofunctional charge transporting structure is at least one of the following structural formula (3). .
However, in the structural formula (3), o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, and Rb and Rc are substituents other than a hydrogen atom and have 1 to 6 carbon atoms. Represents an alkyl group, and a plurality of them may be different. s and t represent an integer of 0 to 3. Za represents a single bond, a methylene group, an ethylene group, or a group represented by the following general formula (4).
< 28 > The image according to any one of < 21 > to < 27 >, wherein the content of the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure is 30 to 70% by mass with respect to the total amount of the protective layer. It is a forming method.
< 29 > The image forming method according to any one of < 21 > to < 28 >, wherein the content of the radical polymerizable compound having a monofunctional charge transporting structure is 30 to 70% by mass relative to the total amount of the protective layer. It is.
< 30 > The image forming method according to any one of < 21 > to < 29 >, wherein the protective layer is cured by heating or light energy irradiation.
< 31 > An electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier. Developing means for developing the electrostatic latent image with toner to form a visible image; transfer means for transferring the visible image to a recording medium; and fixing for fixing the transferred image transferred to the recording medium An image forming apparatus having means,
An image forming apparatus, wherein an image is formed by the image forming method according to any one of <1> to < 30 >.
< 32 > The image forming apparatus according to < 31 >, wherein the transfer unit employs a direct transfer method in which a visible image is directly transferred to a recording medium.
< 33 > From < 31 > to < 31 >, in which a plurality of image forming elements each including an electrostatic latent image carrier, a charging unit, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit are arranged. 32 >.
< 34 > An electrostatic latent image carrier and electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and further developing the electrostatic latent image with toner. And at least one selected from developing means for forming a visible image, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the electrostatic latent image carrier. A process cartridge which is detachably attached to an image forming apparatus main body and forms an image by the image forming method according to any one of <1> to < 30 >.

According to the present invention, various problems in the prior art can be solved, the side effects caused by using a small diameter beam with a diameter of 50 μm or less as a writing light source are reduced, and the image quality is improved by taking advantage of the advantages, and repeated use. However, the occurrence of abnormal images is small, high-quality images can be stably maintained, and both image quality and high stability are achieved, and an image forming method that achieves a long life, and an image forming apparatus that forms an image by the method And a process cartridge can be provided.
That is, by forming a subbing layer having a laminated structure of a charge blocking layer and a moiré preventing layer, and adding a titanyl phthalocyanine crystal having the specific crystal type having higher stability and less aggregation to the photosensitive layer, Soil contamination, which was the biggest factor that determines the life of an electrostatic latent image carrier, is greatly suppressed, and even if the electric field strength is increased, the effect on soil contamination and dielectric breakdown can be greatly reduced. Even if the beam diameter of the exposure light source is reduced, it is possible to obtain the effect sufficiently, thereby realizing high image quality. Furthermore, since it is excellent in image quality stability even in repeated use, it is possible to stably maintain high-quality images, achieving both high image quality and high stability, and realizing a long life, With this method, it is possible to provide an image forming apparatus and a process cartridge for forming an image.

(Image forming method)
The image forming method of the present invention comprises a charging step of charging the surface of an electrostatic latent image carrier with an electric field strength of a value obtained by the following mathematical formula of 30 V / μm or more, and a beam diameter on the electrostatic latent image carrier. An electrostatic latent image forming step of forming an electrostatic latent image using a light source of 50 μm or less; a developing step of developing the electrostatic latent image with toner to form a visible image; and An image forming method comprising a transfer step of transferring to a recording medium and a fixing step of fixing the transferred image transferred to the recording medium,
The electrostatic latent image bearing member is formed by laminating at least a charge blocking layer, a moire preventing layer, and a photosensitive layer in this order on a conductive support, and an average particle diameter of primary particles in the photosensitive layer. Has a maximum value of 27.2 ° as the diffraction value of the Bragg angle 2θ in the error range ± 0.2 ° with respect to the X-ray having a wavelength of 1.542 mm by the CuKα ray, 7.3 °, 9.4 °, 9.6 °, and 24.0 ° have at least maximum values, and more than 7.3 and less than 9.4 °, and 26.3 ° have maximum values. Not containing titanyl phthalocyanine crystals.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)

-Electrostatic latent image carrier-
As described above, the electrostatic latent image carrier of the present invention is formed by laminating at least a charge blocking layer, a moire preventing layer, and a photosensitive layer in this order on a conductive support. The average particle diameter of the primary particles is 0.25 μm or less, and the diffraction value of the Bragg angle 2θ in the error range ± 0.2 ° with respect to the X-ray having a wavelength of 1.542 mm by the CuKα ray is maximum at 27.2 °. And at least maximum values of 7.3 °, 9.4 °, 9.6 °, and 24.0 °, and more than 7.3 and less than 9.4 °, and 26. Includes titanyl phthalocyanine crystals that do not have a maximum at 3 °.
By using the titanyl phthalocyanine crystal, it is possible to obtain a stable electrophotographic electrostatic latent image carrier that does not cause deterioration in chargeability even after repeated use without losing high sensitivity. Japanese Patent Application Laid-Open No. 2001-19871 discloses a charge generating material (the same crystal type) used in the present invention, an electrostatic latent image carrier using the same, an electrophotographic apparatus, and the like. However, when it is used at a resolution of 600 dpi or higher or 1200 dpi or higher, when it is used for a very long period of time, it causes scumming and determines the lifetime of the electrostatic latent image carrier. . Such a phenomenon appears remarkably when used in an image forming apparatus that is faster than the image forming apparatus described in the publication. As a result of detailed examination of this phenomenon, the present inventors have found that this phenomenon can be controlled by controlling the particle size of titanyl phthalocyanine. As described above, the electrostatic latent image carrier having the past configuration does not necessarily sufficiently draw out the ability of the material described in the publication.

  In addition, the above publication does not include a description about the particle size and a technique for controlling the particle size, and the particle size is not optimized. In the present invention, an electrostatic latent image carrier having a specific crystal type titanyl phthalocyanine with a controlled particle diameter and further having an appropriate intermediate layer (consisting of a laminated structure of a charge blocking layer and a moire preventing layer) It is used to construct a more optimal image forming method.

On the other hand, the structure of the intermediate layer in which the charge blocking layer and the moire preventing layer are laminated in this order between the conductive support and the photosensitive layer is a technique described in Japanese Patent Laid-Open No. 5-100461, as described above. However, in the combination with the photosensitive layer capable of achieving high sensitivity, the influence of the generation of heat carriers in the photosensitive layer is large, and the background contamination cannot always be prevented completely. This tendency becomes a significant problem when a charge generating material having absorption at a long wavelength typified by a titanyl phthalocyanine crystal as used in the present invention is used.
Therefore, both technologies are unfinished technologies, and an electrostatic latent image having an intermediate layer in which a titanyl phthalocyanine crystal having the specific crystal type as described above is used as a photosensitive layer and a charge blocking layer and a moire preventing layer are laminated in this order. When a carrier is produced, high sensitivity and electrostatic stability are exhibited, but the improvement in soil dirt durability and prevention of dielectric breakdown by a charging member, which are the objects of the present invention, are not satisfactory. It was.

  As described above, although a method for suppressing scumming in the undercoat layer or the charge generation layer has been disclosed, there are a plurality of scumming factors, and a situation where they are used repeatedly for a long time unless they are simultaneously suppressed. It is impossible to bear down. Although it is a very small cause of soiling, even if it does not become a problem in the initial state, it can be used as the electrostatic latent image carrier is fatigued by repeated use or the deterioration of the constituent materials progresses. The factor is to grow. Therefore, it is necessary to eliminate the cause of background contamination as much as possible and to improve the stability against fatigue of the electrostatic latent image carrier in repeated use. However, there has been no disclosure of a method for solving these problems at the same time and enabling dramatic improvement in durability.

  Therefore, a technique for controlling the particle size of titanyl phthalocyanine crystal to 0.25 μm or less by the method as described below is further combined, that is, the soiling caused by many factors is suppressed and the charging property is reduced. It was found that by improving the temporal stability and further minimizing the side effects on residual potential and environmental dependence, it was possible to maintain a stable effect even after repeated use and achieve the object of the present invention. .

--Method of synthesizing titanyl phthalocyanine crystal--
As a method for synthesizing a titanyl phthalocyanine crystal, for example, as described in JP-A-6-293769, a method in which titanium halide is not used as a raw material can be preferably exemplified. The biggest merit of this method is that the synthesized titanyl phthalocyanine crystal is free of halogenation. If the titanyl phthalocyanine crystal contains a halogenated titanyl phthalocyanine crystal as an impurity, the electrostatic characteristics of an electrostatic latent image carrier using the crystal may have adverse effects such as a decrease in photosensitivity and a decrease in chargeability (Japan). Hardcopy '89 Proceedings p. 103). Also in the present invention, halogenated free titanyl phthalocyanine crystals as described in JP-A-2001-19871 are mainly used, and these materials are effectively used.
In order to synthesize a halogenated free titanyl phthalocyanine, it is necessary not to use a halogenated material as a raw material in the synthesis of titanyl phthalocyanine. Specifically, the method described later is used.

  First, a method for synthesizing a crude product of titanyl phthalocyanine crystal will be described. Methods for synthesizing phthalocyanines have been known for a long time, and are described in “Phthalogyanine Compounds” (1963), “The Phthalogianines” (1983), JP-A-6-293769, and the like.

  For example, as a first method, a mixture of phthalic anhydrides, metal or metal halide and urea is heated in the presence or absence of a high boiling point solvent. At this time, a catalyst such as ammonium molybdate is used in combination as necessary. As a second method, phthalonitriles and metal halides are heated in the presence or absence of a high boiling point solvent. This method is used for phthalocyanines that cannot be produced by the first method, such as aluminum phthalocyanines, indium phthalocyanines, oxovanadium phthalocyanines, oxotitanium phthalocyanines, zirconium phthalocyanines, and the like. The third method is to first react phthalic anhydride or phthalonitrile with ammonia to produce an intermediate such as 1,3-diiminoisoindoline, and then react with a metal halide in a high boiling solvent. It is a method to make it. The fourth method is a method in which phthalonitriles and a metal alkoxide are reacted in the presence of urea or the like. In particular, the fourth method does not cause chlorination (halogenation) to the benzene ring, and is a very useful method as a method for synthesizing an electrophotographic material, and is used extremely effectively in the present invention.

  Next, a method for synthesizing amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) will be described. In this method, phthalocyanines are dissolved in sulfuric acid, diluted with water and reprecipitated, and an acid paste method or an acid slurry method can be used.

  As a specific method, the above synthetic crude product is dissolved in 10-50 times the amount of concentrated sulfuric acid, and if necessary, insoluble matter is removed by filtration or the like, and this is sufficiently cooled to 10-50 times the amount of sulfuric acid. Slowly throw it into water or ice water to reprecipitate titanyl phthalocyanine. The precipitated titanyl phthalocyanine is filtered, washed with ion-exchanged water and filtered, and this operation is sufficiently repeated until the filtrate becomes neutral. Finally, after washing with clean ion-exchanged water, filtration is performed to obtain a water paste having a solid content concentration of about 5 to 15% by mass.

  At this time, it is important to thoroughly wash with ion-exchanged water so as not to leave concentrated sulfuric acid as much as possible. Specifically, it is preferable that the ion-exchanged water after washing exhibits the following physical property values. That is, if the remaining amount of sulfuric acid is expressed quantitatively, it can be expressed by pH and specific conductivity of ion-exchanged water after washing. When expressed in terms of pH, the pH is preferably in the range of 6-8. By being within this range, it can be determined that the amount of sulfuric acid remaining does not affect the characteristics of the electrostatic latent image carrier. This pH value can be easily measured with a commercially available pH meter. In terms of specific conductivity, it is preferably 8 μS / cm or less, more preferably 5 μS / cm or less, and most preferably 3 μS / cm or less. Within this range, it can be determined that the residual amount of sulfuric acid does not affect the characteristics of the electrostatic latent image carrier. This specific conductivity can be measured with a commercially available electric conductivity meter. The lower limit of the specific conductivity is the specific conductivity of the ion exchange water used for cleaning. In any measurement, in the range deviating from the above range, the remaining amount of sulfuric acid is large, and the chargeability of the electrostatic latent image carrier may be lowered or the photosensitivity may be deteriorated.

  What was produced in this way was the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used in the present invention. At this time, the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) has a diffraction value (error ± 0.2 °) of Bragg angle 2θ with respect to X-rays at a wavelength of 1.542 mm of CuKα of at least 7.0 to 7. A maximum value of 5 ° is preferred. Moreover, it is preferable that the half value width of the diffraction value is 1 ° or more. Furthermore, it is preferable that an average particle diameter is 0.1 micrometer or less.

Next, a crystallization method will be described.
The crystallization is performed by using the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) as a diffraction value (error ± 0.2 °) of Bragg angle 2θ with respect to X-ray having a wavelength of 1.542 mm by CuKα. And at least maximum values of 7.3 °, 9.4 °, 9.6 °, and 24.0 °, and a maximum value of more than 7.3 and less than 9.4 °. It is the process of converting into the titanyl phthalocyanine crystal | crystallization which does not have.

As a specific method, the crystal is obtained by mixing and stirring the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) with an organic solvent in the presence of water without drying.
At this time, the organic solvent to be used is not particularly limited as long as a desired crystal can be obtained. In particular, tetrahydrofuran, toluene, methylene chloride, carbon disulfide, orthodichlorobenzene, 1,1,2- Trichloroethane is preferred. These organic solvents are preferably used alone, but two or more of these organic solvents may be mixed, or may be used by mixing with other solvents. The amount of the organic solvent used for crystallization is preferably 10 times or more, more preferably 30 times or more the weight of amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine). This is because crystal conversion is caused quickly and sufficiently, and an effect of sufficiently removing impurities contained in amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is exhibited. The amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used here is prepared by the acid paste method, but it is preferable to use one obtained by sufficiently washing sulfuric acid as described above. When crystal conversion is performed under conditions where sulfuric acid remains, sulfate ions may remain in the crystal particles, and the obtained crystal may not be completely removed even if it is subjected to an operation such as a water washing treatment. If sulfate ions remain, the electrostatic latent image bearing member may be reduced in sensitivity and chargeability. For example, Japanese Patent Application Laid-Open No. 8-110649 discloses a method for crystal conversion by adding titanyl phthalocyanine dissolved in sulfuric acid into an organic solvent together with ion-exchanged water. This method can also obtain a crystal similar to the X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in the present invention, but the sulfate ion concentration in titanyl phthalocyanine is high and the light attenuation characteristic (photosensitivity) is poor. For this reason, the method for producing titanyl phthalocyanine of the present invention is not good.

In the charge generation material contained in the electrostatic latent image carrier of the present invention, the particle size of the titanyl phthalocyanine crystal is made finer, so that the effect of suppressing scumming is enhanced, and it is effective for image quality stability and longer life. It becomes. The manufacturing method is shown below.
There are mainly two methods for controlling the particle size of titanyl phthalocyanine crystals contained in the photosensitive layer. One is a method of synthesizing a crystal containing no particles larger than 0.25 μm when synthesizing titanyl phthalocyanine crystal particles, and the other is a coarse particle larger than 0.25 μm after the titanyl phthalocyanine crystal is dispersed. Any one of these may be used alone, or both may be used in combination.

First, a method for synthesizing crystals that do not contain particles larger than 0.25 μm will be described. In FIGS. 10 and 11, the scale bar is 0.2 μm.
In order to make the particle size of the titanyl phthalocyanine crystal finer, the inventors have observed that the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) has a primary particle size as shown in FIG. Although it is 0.1 μm or less (most of which is about 0.01 to 0.05 μm), it has been found that the particle diameter changes with crystal growth during crystallization. Usually, in this type of crystallization, a sufficient crystallization time is ensured in fear of remaining of the raw material, and after sufficient crystallization is performed, filtration is performed to obtain a desired titanyl phthalocyanine crystal. is there. For this reason, even though a raw material having sufficiently small primary particles is used as the raw material, the resulting crystal has a large primary particle crystal (approximately 0.3 to 0.5 μm) as shown in FIG. It is what you have obtained.

  In dispersing the obtained titanyl phthalocyanine crystal, dispersion is performed by giving a strong share to reduce the particle size after dispersion (0.25 μm or less), and further, primary particles are pulverized as necessary. Dispersing by giving strong energy. As a result, as described above, there is a possibility that a part of the particles may be transferred to a crystal which is not a desired type.

  In this regard, by controlling the primary particle diameter of the titanyl phthalocyanine crystal from the synthesis stage, a method for solving this problem is possible by obtaining a crystal having a small size, which is effectively used in the present invention. Specifically, a range in which crystal growth hardly occurs during crystallization (a range in which the size of the amorphous titanyl phthalocyanine particles observed in FIG. 10 is insignificantly small after crystallization, approximately 0.25 μm or less. ) Is to obtain a titanyl phthalocyanine crystal having the smallest primary particle size as much as possible by determining when the crystallization is completed. The particle size after crystallization increases in proportion to the crystallization time. Therefore, as described above, it is important to increase the efficiency of crystallization and complete the process in a short time. There are several important points for this.

  One is to select an appropriate crystallization solvent as described above to increase the crystallization efficiency. The other is to use strong stirring to bring the solvent into contact with the titanyl phthalocyanine water paste (raw material prepared as described above: amorphous titanyl phthalocyanine) in order to complete the crystallization in a short time. Specifically, crystallization can be achieved in a short time by using a method such as stirring using a propeller with a very strong stirring force, or using a strong stirring (dispersing) means such as a homogenizer (homomixer). is there. Under these conditions, it is possible to obtain a titanyl phthalocyanine crystal in which crystallization is sufficiently performed and crystal growth does not occur without the raw material remaining. Also in this case, optimization of the amount of the organic solvent used for crystallization is an effective means. Specifically, it is desirable to use 10 times or more, preferably 30 times or more of the organic solvent with respect to the solid content of the amorphous titanyl phthalocyanine. As a result, crystallization can be ensured in a short time and impurities contained in the amorphous titanyl phthalocyanine can be surely removed.

  In addition, since the crystal particle diameter and the crystallization time are in a proportional relationship as described above, a method of stopping the reaction immediately after completion of a predetermined reaction (crystallization) is also an effective means. As the above-mentioned means, a large amount of a solvent that hardly causes crystallization is immediately added after crystallization as described above. Examples of the solvent that hardly causes crystallization include alcohol solvents and ester solvents. Crystallization can be stopped by adding about 10 times these solvents to the crystallization solvent.

  The smaller the primary particle diameter produced in this way, the better the results with respect to the problem of the electrostatic latent image carrier, but the next process (pigment filtration process) for pigment production, dispersion Considering dispersion stability in a liquid, side effects may occur even if it is too small. That is, when the primary particles are very fine, there arises a problem that the filtration time becomes very long in the step of filtering the primary particles. In addition, when the primary particles are too fine, the surface area of the pigment particles in the dispersion increases, so that the possibility of reaggregation of the particles increases. Accordingly, the particle diameter of the pigment particles is preferably about 0.05 μm to 0.2 μm.

FIG. 12 shows a TEM image of a titanyl phthalocyanine crystal when crystallization is performed in a short time (the scale bar in the figure is 0.2 μm). Unlike the case of FIG. 11, the particle size is small and almost uniform, and no coarse particles as observed in FIG. 11 are observed.
In dispersing the titanyl phthalocyanine crystal produced in a state where the primary particles are small as shown in FIG. 10, the particle diameter after dispersion is made small (0.25 μm or less, more preferably 0.2 μm or less). Can be dispersed by giving a share sufficient to loosen the secondary particles formed by aggregation of the primary particles. As a result, since energy more than necessary is not given, as described above, it is possible to easily produce a dispersion having a fine particle size distribution without producing a result that a part of the particles are easily transferred to crystals that are not of the desired type. Is possible.

  The particle diameter here means a volume average particle diameter, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). At this time, the particle diameter (Median system) corresponding to 50% of the cumulative distribution is calculated. However, this method may not be able to detect a very small amount of coarse particles. Therefore, in order to obtain more details, it is important to observe the titanyl phthalocyanine crystal powder or dispersion directly with an electron microscope and determine its size. It is.

  As a result of further observation of the dispersion and examination of micro defects, the above phenomenon was understood as follows. Usually, in the method of measuring the average particle diameter, when extremely large particles are present in a few percent or more, the presence can be detected, but the amount is as small as about 1% or less of the whole. The measurement would be below the detection limit. As a result, the presence of coarse particles is not detected only by measuring the average particle size, making it difficult to interpret the above minute defects.

FIG. 13 and FIG. 14 show photographs observing the state of two types of dispersions in which only the dispersion time is changed while fixing the dispersion conditions. A photograph of a dispersion liquid having a short dispersion time under the same conditions is shown in FIG. 13. Compared with FIG. 14 having a long dispersion time, coarse particles observed as black particles in FIG. 13 remain. .
The average particle size and particle size distribution of these two types of dispersions were measured by a commercially available particle size distribution measuring device (manufactured by Horiba: ultracentrifugal automatic particle size distribution measuring device, CAPA 700). The result is shown in FIG. “A” in FIG. 15 corresponds to the dispersion shown in FIG. 13, and “B” corresponds to the dispersion shown in FIG. When both are compared, there is almost no difference in the particle size distribution. In addition, the average particle diameter values of the two are “A” of 0.29 μm and “B” of 0.28 μm, and it cannot be determined that there is a difference between the two, taking measurement errors into account.

  Therefore, it is difficult to detect the presence of a minute amount of coarse particles only by the definition of the known average particle diameter, and it is difficult to clarify the relationship with the background dirt. The presence of this minute amount of coarse particles is recognized for the first time by observing the coating liquid at the microscope level, and this makes it possible to clarify the relationship with the background stain.

From these results, in order to make the primary particles produced during crystallization as small as possible while suppressing aggregation, an appropriate crystallization solvent is selected as described above, while increasing the crystallization efficiency, In order to complete the crystallization in a short time, it can be seen that a technique using strong stirring is effective for sufficiently bringing the solvent into contact with the titanyl phthalocyanine aqueous paste (the raw material prepared as described above).
By employing such a crystallization method, a titanyl phthalocyanine crystal having a small primary average particle diameter (0.25 μm or less, preferably 0.2 μm or less) can be obtained. In addition to the technique described in Japanese Patent Application Laid-Open No. 2001-19871, the use of the above-described technique (crystallization method for obtaining fine titanyl phthalocyanine crystal) in combination with the effect of the present invention as necessary. It is an effective means to increase.

Subsequently, the crystallized titanyl phthalocyanine crystal is immediately filtered to be separated from the crystal conversion solvent. This filtration is performed by using a filter of an appropriate size. In this case, it is most appropriate to use vacuum filtration.
Thereafter, the separated titanyl phthalocyanine crystal is heat-dried as necessary. Any known dryer can be used for heating and drying, but a blower-type dryer is preferable when the drying is performed in the atmosphere. Furthermore, drying under reduced pressure is also a very effective means in order to increase the drying speed and to exhibit the effects of the present invention more remarkably. In particular, this is an effective means for a material that decomposes at a high temperature or changes its crystal form. It is particularly effective to dry in a state where the degree of vacuum is higher than 10 mmHg.

  The thus obtained titanyl phthalocyanine crystal having a specific crystal type is extremely useful as a charge generating material for an electrophotographic electrostatic latent image carrier. However, as described above, the crystal is unstable and has a drawback that the crystal form is easily transferred when a dispersion is prepared. However, by synthesizing primary particles into infinitely small particles as in the present invention, a dispersion with a small average particle diameter can be prepared without giving an excessive share during the preparation of the dispersion, and the crystal type is extremely It can be produced stably (without changing the synthesized crystal form).

Next, a method for preparing the dispersion will be described.
A general method is used for the preparation of the dispersion, and the titanyl phthalocyanine crystal is dispersed in a suitable solvent together with a binder resin as necessary by using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. It is obtained. At this time, the binder resin may be selected depending on the electrostatic characteristics of the electrostatic latent image carrier, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

Next, a method for removing particles of 0.25 μm or more after dispersing titanyl phthalocyanine crystals having a specific crystal type will be described.
As described above, the titanyl phthalocyanine crystal having the maximum diffraction peak at 27.2 ° as the diffraction value of the Bragg angle 2θ in the error range ± 0.2 ° with respect to the X-ray having the wavelength of 1.542 mm by the CuKα ray is It is known to easily undergo crystal transition to other types due to stress such as energy and mechanical share. This tendency does not change in the titanyl phthalocyanine crystal used in the present invention. In other words, in order to prepare a dispersion containing fine particles, it is necessary to devise a dispersion method, but the stability of the crystal and the formation of fine particles tend to be in a trade-off relationship. Although there are methods for avoiding this by optimizing the dispersion conditions, all of them make the manufacturing conditions extremely narrow, and a simpler method is desired. In order to solve this problem, the following method is also an effective means.

  That is, it is a method in which a dispersion liquid in which the particles are made as fine as possible is produced within a range where crystal transition does not occur, and then filtered through an appropriate filter. This method is a very effective means in that it can remove a minute amount of coarse particles that cannot be visually observed (or cannot be detected by particle size measurement), and that the particle size distribution is uniform. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore size of 3 μm or less, more preferably 1 μm or less, thereby completing the dispersion. Also by this method, a dispersion liquid containing only titanyl phthalocyanine crystals having a small particle diameter (0.25 μm or less, more preferably 0.2 μm or less) can be produced, and an electrostatic latent image carrier using this can be imaged. By mounting and using it in the forming apparatus, it is possible to increase the margin against soiling, which is effective for enhancing the durability of the electrostatic latent image carrier.

  The filter for filtering the dispersion varies depending on the size of coarse particles to be removed, but according to the study by the present inventors, an electrostatic latent image bearing carrier used in an electrophotographic apparatus that requires a resolution of about 600 dpi. As a body, the presence of coarse particles of 3 μm or more at least affects the image. Therefore, the size of the filter to be used is preferably a pore diameter of less than 3 μm, and more preferably 1 μm or less. By performing such a filtering process, coarse particles finer than the pore diameter can be removed, and a dispersion having a narrow particle size distribution and no coarse particles can be produced.

  As for the pore size of the filter, the finer the particle, the more effective the removal of coarse particles. However, if the particle size is too fine, the necessary pigment particles themselves are also filtered, and therefore there is an appropriate size. In addition, if it is too fine, it takes time for filtration, clogging of the filter, and excessive load is applied when liquid is sent using a pump or the like. In addition, as a material of the filter used here, a material resistant to the solvent used in the dispersion to be filtered is preferably used.

  During filtration, if the amount of coarse particles in the dispersion to be filtered is too large, more pigment is removed, and the solid content concentration of the dispersion after filtration may change. Therefore, there is an appropriate particle size distribution (particle size, standard deviation) when filtering. As in the present invention, in order to perform filtration efficiently without loss of pigment due to filtration and clogging of the filter, the average particle size of the dispersion before filtration is 0.3 μm or less, and its standard deviation is 0. It is preferable to disperse to 2 μm or less.

  By adding such an operation of filtering the dispersion, coarse particles can be removed, and as a result, background contamination generated on the electrostatic latent image carrier using the dispersion can be reduced. As described above, the finer the filter, the greater the effect (reliable), but there are cases where the pigment particles themselves are filtered. In such a case, using the titanyl phthalocyanine primary particles described above in combination with the technique for refining and synthesizing the particles produces a very large effect. That is, (i) by synthesizing and using refined titanyl phthalocyanine, the dispersion time can be shortened and the dispersion stress can be reduced, and the possibility of crystal transition in dispersion is reduced. (Ii) Since the coarse particle diameter remaining by the dispersion is smaller than that in the case where the fine particles are not refined, a smaller filter can be used, and the effect of removing the coarse particles becomes more reliable. In addition, the amount of titanyl phthalocyanine particles to be removed is reduced, and there is little change in the composition of the dispersion before and after filtration, which enables stable production. (Iii) As a result, the manufactured electrostatic latent image carrier is stably produced with a high anti-smudge property.

--- Configuration example-
Examples of the configuration of the electrostatic latent image carrier include the following.
FIG. 16 shows a structure in which a charge blocking layer 205, a moiré preventing layer 206, and a photosensitive layer 204 having a specific crystal type and containing a titanyl phthalocyanine crystal having a specific average particle diameter or less are sequentially laminated on a conductive support 201. Have taken.
FIG. 17 shows a charge generation layer 207 in which a photosensitive layer has a specific crystal and a titanyl phthalocyanine crystal having a specific average particle size or less on a moire prevention layer 206, and a charge transport layer 208 mainly composed of a charge transport material. Are sequentially stacked.
FIG. 18 has a configuration in which a protective layer 209 is laminated on a photosensitive layer composed of a charge generation layer 207 and a charge transport layer 208.

--Conductive support--
Examples of the conductive support 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, indium oxide, etc. The metal oxide of the above is coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc. After pipe formation, a surface treated pipe such as cut, superfinished or polished is preferably used. Further, endless nickel belts and endless stainless steel belts are also preferably used.

In addition, the conductive support dispersed in a suitable binder resin on the support can be used as the conductive support of the present invention.
Examples of the conductive powder include metal powders such as carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powders such as conductive tin oxide and ITO. .
The binder resin used simultaneously 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-vinyl carbazole, 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.
The conductive support can be provided by dispersing and applying 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 are also preferably used.

-Charge blocking layer and moire prevention layer-
The role of the undercoat layer such as the charge blocking layer and the moiré preventing layer is to suppress the injection of reverse polarity charges induced in the conductive support during charging of the electrostatic latent image carrier, and to prevent moiré. It has many roles such as concealing defects in the tube, and maintaining the adhesion of the photosensitive layer. When the undercoat layer is a single layer as usual, the residual potential tends to increase when the charge injection from the conductive support is suppressed, and conversely, if the residual potential is reduced, the soiling becomes worse. As a result of functional separation of such a trade-off relationship by forming a plurality of undercoat layers, the scumming suppression effect can be remarkably improved without greatly affecting the residual potential. In the present invention, the effect is exhibited by laminating a plurality of undercoat layers. In particular, an undercoat layer containing no inorganic pigment (charge blocking layer) and an undercoat layer containing an inorganic pigment ( Since at least two layers of moiré prevention layers are laminated in this order, there is little influence on the residual potential, it is possible to greatly enhance the effect of suppressing soiling, no side effects on moire and adhesiveness, It is possible to obtain a very large effect on the high durability of the latent image carrier.

First, the charge blocking layer whose main purpose is to suppress charge injection from the conductive support will be described.
The charge blocking layer is a layer that has the function of preventing the reverse polarity charge induced on the electrode during charging of the electrostatic latent image carrier from being injected into the photosensitive layer from the support, and mainly suppresses background contamination. It is a layer aimed at. In the case of negative charging, it has a function of preventing hole injection, and in the case of positive charging, it has a function of preventing electron injection. Moreover, it also has the effect of improving the concealment property against defects in the raw tube, and enhances the effect of suppressing soiling. Therefore, since it is required to suppress the movement of electric charges in order to achieve these objects, it is preferable that the resin is composed only of a highly insulating resin without containing an inorganic pigment.
Examples of the charge blocking layer include an anodized film typified by an aluminum oxide layer, an inorganic insulating layer typified by SiO, and a glassy network of metal oxide as described in JP-A No. 64-1728. A layer formed, a layer made of polyphosphazene as described in JP-A-11-5919, a layer made of an aminosilane reaction product as described in JP-A-3-269644, an insulating bond. Examples include a layer made of an adhesive resin and a layer made of a curable binder resin. Among these, a layer composed of an insulating binder resin or a curable binder resin that can be formed by a wet coating method is preferably used. Since the charge blocking layer is formed by laminating a moire preventing layer and a photosensitive layer on the charge blocking layer, when these are provided by a wet coating method, the charge blocking layer must be composed of a material or a structure that does not attack the coating film by these coating solvents. is required.

Examples of the binder resin include thermoplastic resins such as polyamide, polyester, and vinyl chloride-vinyl acetate copolymer, and thermosetting resins.
More specifically, a compound containing a plurality of active hydrogens (hydrogen such as —OH group, —NH ₂ group, and —NH group) and a compound containing a plurality of at least one of an isocyanate group and an epoxy group. The thermosetting resin etc. which were thermopolymerized are mentioned.
Examples of the compound containing a plurality of active hydrogens include acrylic resins containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, and hydroxyethyl methacrylate groups. Resin, etc. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and their prepolymers. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resins, Etc.
Also, an oil-free alkyd resin, a thermosetting resin obtained by thermal polymerization of an amino resin such as a butylated melamine resin, a polyurethane having an unsaturated bond, a resin having an unsaturated bond such as an unsaturated polyester, and a thioxanthone series A photocurable resin such as a combination of a compound and a photopolymerization initiator such as methylbenzylformate is also included.
These alcohol-soluble resins and thermosetting resins have high insulation properties, and the liquid applied to the upper layer contains many ketone solvents, so that the film does not elute during coating. Since a uniform film is maintained, the stability and uniformity of the antifouling effect are excellent.

Among these resins, polyamide is preferable, and N-methoxymethylated nylon is most preferable among them. The polyamide resin has a high effect of suppressing charge injection and has little influence on the residual potential. In addition, these polyamide resins are alcohol-soluble resins, are insoluble in other solvents, can form a uniform thin film even in dip coating, and have excellent coating properties. . In particular, this subbing layer needs to be a thin film in order to minimize the effect of the increase in residual potential, and the uniformity of the film thickness is required. have.
In general, alcohol-soluble resins are highly humidity-dependent, which increases resistance in low-humidity environments and increases residual potential.In high-humidity environments, resistance decreases, leading to a decrease in charge and large environmental dependency. It was a challenge. However, among the polyamide resins, N-methoxymethylated nylon exhibits high insulating properties, is very excellent in blocking properties of charges injected from the conductive support, has little influence on the residual potential, and is environmentally friendly. Since the dependence is greatly reduced and stable image quality can be maintained even when the use environment of the image forming apparatus changes, it is most preferably used when a moire prevention layer is laminated thereon. In addition, when N-methoxymethylated nylon is used, the film thickness dependence of the residual potential is small, so that it is possible to reduce the influence on the residual potential and obtain a high scumming suppression effect.

  The substitution rate of the methoxymethyl group in N-methoxymethylated nylon is not particularly limited, but is preferably 15 mol% or more. The above-mentioned effect due to the use of N-methoxymethylated nylon is affected by the degree of methoxymethylation. When the substitution rate of the methoxymethyl group is lower than this, the dependency on humidity increases, and when an alcohol solution is used, the cloudiness is increased. The stability of the coating solution over time may be slightly reduced.

  In the present invention, N-methoxymethylated nylon can be used alone, but in some cases, a crosslinking agent or an acid catalyst can be added. A commercially available material such as a conventionally known melamine resin or isocyanate resin is used as the crosslinking agent, and an acidic catalyst is used as the catalyst, and a general-purpose catalyst such as tartaric acid can be used. However, since the insulating property of the undercoat layer is lowered by the addition of the acid catalyst, and the effect of suppressing soiling may be reduced, the addition amount needs to be very small. 5 mass% or less is preferable with respect to resin. In some cases, other binder resins can be mixed. As the binder resin that can be mixed, a polyamide resin exhibiting alcohol solubility is used, and the stability of the liquid over time may be increased.

  In addition, it is possible to add a conductive polymer, an acceptor (donor) resin or a low molecular weight compound, and other various additives in accordance with the charging polarity, which may be effective in reducing the residual potential. However, when the upper layer is laminated by dip coating, it is preferable to keep the addition amount to a minimum because these additives may be dissolved.

The thickness of the charge blocking layer is preferably from 0.3 μm to less than 2.0 μm, and more preferably from 0.3 μm to 1.0 μm. If the film thickness is 2.0 μm or more, the residual potential may be significantly increased particularly at low temperature and low humidity due to repeated charging and exposure, and if it is less than 0.3 μm, the blocking effect is reduced. There is,
In addition, the charge blocking layer may be added with chemicals, solvents, additives, curing accelerators, and the like necessary for curing (crosslinking) as necessary, and blade coating, dip coating, spray coating, It is formed on the substrate by beat coating, nozzle coating, or the like. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

  Next, a moiré preventing layer that is effective for reducing moire and reducing the charge potential due to fatigue and residual potential will be described. This moiré preventing layer also has an effect of suppressing scumming, but is required to have a function of preventing moiré or improving the adhesion of the photosensitive layer. Therefore, it is preferable to increase the surface roughness of the moire prevention layer, which is achieved by dispersing the inorganic pigment. The moiré preventing layer has the function of suppressing moire by the inorganic pigment contained as described above, reducing the residual potential and dark decay due to fatigue, and further improving the adhesion to the photosensitive layer.

  The above-mentioned moire is a kind of image defect in which interference fringes called moire are formed on an image due to optical interference inside the photosensitive layer when writing with coherent light such as laser light. Basically, it is necessary to contain a material having a large refractive index in order to prevent the occurrence of moire by scattering the incident laser light by the undercoat layer. In order to prevent moiré, a configuration in which an inorganic pigment is dispersed in a binder resin is most effective. In particular, among inorganic pigments, white pigments are effectively used. For example, titanium oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, aluminum oxide, and the like are favorably used. Among these, titanium oxide having a large hiding power is most preferably used.

  The moire prevention layer preferably has a function capable of transferring a charge having the same polarity as the charge charged on the surface of the electrostatic latent image carrier from the photosensitive layer to the conductive support side from the viewpoint of reducing the residual potential, and is inorganic. Pigments also play that role. For example, in the case of a negatively charged electrostatic latent image carrier, the residual layer can be greatly reduced by having an undercoat layer having electronic conductivity. As these inorganic pigments, the above-mentioned metal oxides are used effectively, but residual potential can be increased by using low-resistance metal oxides or increasing the addition ratio of metal oxides to the binder resin more than necessary. However, the effect of suppressing soiling may be reduced. Therefore, it is necessary to achieve both the suppression of background contamination and the reduction of the residual potential by properly using them depending on the layer configuration and film thickness of the undercoat layer in the electrostatic latent image carrier and adjusting the addition amount. . Further, the use of an electron conductive material (for example, an acceptor) or the like for the moire preventing layer makes the effect of the present invention more remarkable.

As the inorganic pigment, the above-mentioned metal oxide is preferably used. However, when using the conductive metal oxide, it is effective in reducing the residual potential, but scumming may increase. In addition, when a metal oxide having a high resistance is used, it is effective in suppressing scumming, but there is a tendency that the residual potential tends to increase. In the present invention, a plurality of undercoat layers composed of a charge blocking layer and a moire preventing layer are formed, and “the functional separation allows the inorganic pigment to be selected in a wider range. Even if it has a subbing layer that does not contain, the resistance of the inorganic pigment contained in the subbing layer that contains the inorganic pigment has a considerable influence on the soiling and residual potential. It is preferable to use a metal oxide having a higher resistance than that of a conductive metal oxide, and among these metal oxides, titanium oxide is most preferable from the viewpoint of image quality stability.
As the titanium oxide, high purity is more preferable in reducing the increase in residual potential. The specific purity is preferably 99.0% or more, more preferably 99.5% or more.

  The average primary particle diameter of the inorganic pigment is preferably 0.01 μm to 0.8 μm, more preferably 0.05 μm to 0.5 μm. However, when only an inorganic pigment having an average primary particle size of 0.1 μm or less is used, it is effective for reducing background stains, but the moire prevention effect may be lowered, while the average primary particle size is 0.00. When only a metal oxide larger than 4 μm is used, although the moire prevention effect is excellent, the background dirt suppression effect may be slightly reduced. At this time, it is preferable to use a mixture of inorganic pigments having different average primary particle sizes, since both reduction of background stains and reduction of moire can be achieved, and an effect can also be seen in reducing residual potential. .

As the binder resin, the same resin as the charge blocking layer can be used. However, considering that the photosensitive layer is laminated on the moire preventing layer 6, a binder resin that is insoluble in the coating solvent for the photosensitive layer is preferable.
Examples of such a binder resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as polyamide, copolymer nylon, and methoxymethylated nylon, polyurethane, phenol resin, alkyd melamine resin, Examples thereof include an epoxy resin and a curable resin that forms a three-dimensional network structure. Among these resins, the curable resins are most preferably used because they are cured and have a very small influence of elution by an organic solvent when the photosensitive layer is applied on the undercoat layer. .
Among the curable resins, an alkyd / melamine resin mixture is most preferable from the viewpoint of residual potential and environmental stability.
At this time, the mixing ratio of alkyd / melamine resin is an important factor that determines the structure and characteristics of the moire prevention layer. Specifically, the ratio of the two is preferably in the range of 5/5 to 8/2 by weight. When the amount of melamine resin is more than 5/5, volume shrinkage is increased during thermosetting, and coating film defects are likely to occur, or the residual potential of the electrostatic latent image carrier may be increased. On the other hand, when the amount of alkyd resin is more than 8/2, the residual potential of the electrostatic latent image bearing member is reduced, but the bulk resistance becomes too low and the soiling may be deteriorated.

In the moire prevention layer, the volume ratio of the inorganic pigment and the binder resin determines an important characteristic. For this reason, it is preferable that the volume ratio of the inorganic pigment and the binder resin is in a range of 1/1 to 3/1. When the volume ratio is less than 1/1, not only the moire preventing ability is lowered, but also the increase in residual potential in repeated use may be increased. On the other hand, when the volume ratio is 3/1 or more, not only the binding ability of the binder resin is inferior, but also the surface property of the coating film is deteriorated, which may adversely affect the film forming property of the upper photosensitive layer. This effect can be a serious problem when the photosensitive layer is a laminated type and a thin layer such as a charge generation layer is formed. In addition, when the volume ratio is 3/1 or more, there are cases where the binder resin cannot cover the surface of the inorganic pigment, and direct contact with the charge generation material increases the probability of heat carrier generation, and prevents soil contamination. May have adverse effects.
Furthermore, by using two or more types of titanium oxides having different average particle diameters for the moire prevention layer, it is possible to improve the concealing power to the conductive substrate and suppress moire and cause abnormal images. Pinholes can be eliminated. For this purpose, the average particle diameter of the largest titanium oxide (hereinafter also referred to as “T1”) having a ratio of the average particle diameters of two or more kinds of titanium oxides used is D1, and the smallest titanium oxide (hereinafter “T1”) is used. T2 ”) is preferably 0.2 <D2 / D1 ≦ 0.5. If the ratio of the average particle diameter of the smallest titanium oxide to the average particle diameter of the largest titanium oxide is too small (0.2> D2 / D1), the activity on the titanium oxide surface increases and the electrophotographic electrostatic latent image is carried. When used as a body, the electrostatic stability may be significantly impaired. In addition, when the ratio of the average particle diameter of the smallest titanium oxide to the average particle diameter of the largest titanium oxide is too large (D2 / D1> 0.5), the hiding power for the conductive substrate is lowered, and the moire and abnormal images are not affected. Suppression is reduced. The average particle size referred to here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.
Further, the size of the average particle diameter (D2) of the smallest titanium oxide is an important factor, and it is preferable that 0.05 μm <D2 <0.20 μm. When the particle diameter is smaller than 0.05 μm, the hiding power is lowered and moire may be generated. On the other hand, when it is larger than 0.20 μm, the filling rate of titanium oxide in the moire preventing layer is lowered, and the soil stain suppressing effect may not be sufficiently exhibited.
The mixing ratio (weight ratio) of T1 and T2 is also an important factor, and it is preferable that 0.2 ≦ T2 / (T1 + T2) ≦ 0.8. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of titanium oxide is not so large, and the soil stain suppression effect may not be sufficiently exhibited. On the other hand, if it is larger than 0.8, the concealing power is lowered and moire may be generated.
Moreover, as a film thickness of a moire prevention layer, 1-10 micrometers is preferable and 2-5 micrometers is more preferable. If the film thickness is less than 1 μm, the effect may be small, and if it exceeds 10 μm, accumulation of residual potential may occur.

  The inorganic pigment is dispersed together with a solvent and a binder resin by a conventional method, for example, ball mill, sand mill, attrier, etc., and if necessary, a chemical, a solvent, an additive, a curing accelerator, etc. necessary for curing (crosslinking) are added. Then, it is formed on the substrate by a blade coating method, a dip coating method, a spray coating method, a beat coating method, a nozzle coating method, or the like. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

--Photosensitive layer--
As the photosensitive layer, the photosensitive layer may be a single-layered photosensitive layer containing a charge generation material and a charge transport material, but a stacked type composed of the charge generation layer and the charge transport layer shown in FIGS. It exhibits excellent characteristics in sensitivity and durability, and is more preferable.
The photosensitive layer, as a charge generation material, has the above-mentioned average primary particle diameter of 0.25 μm or less, and the Bragg angle in an error range of ± 0.2 ° with respect to X-rays having a wavelength of 1.542 mm by CuKα rays The diffraction value of 2θ has a maximum value at 27.2 °, and further has at least local maximum values at 7.3 °, 9.4 °, 9.6 °, and 24.0 °, and 7 It contains titanyl phthalocyanine crystals that are more than 3 and less than 9.4 ° and do not have a maximum at 26.3 °.

  As described above, the effect of suppressing scumming is significantly enhanced by laminating the charge blocking layer and the moire preventing layer, but these effects are due to the suppression of charge injection from the conductive support. It is necessary to take another measure against the soiling caused by the aggregation of the charge generation layer formed thereon and the decrease in purity. According to the present invention, drastic improvement in durability can be realized by suppressing the ground contamination factors in both the undercoat layer and the charge generation layer including the charge blocking layer and the moire preventing layer. Further, the decrease in charge due to repeated use of the electrostatic latent image carrier promotes the occurrence of scumming.In the present invention, by specifying the crystal form and average particle diameter of titanyl phthalocyanine used in the charge generation layer, It was possible to reduce the decrease in electrification and further enhance the effect of suppressing scumming. At the same time, it has become possible to reduce the dependency on humidity, which reduces the dependency on the use environment of the image quality and further enhances the stabilization of the image quality. An improvement was realized.

<Charge generation layer>
The charge generation layer is prepared by dispersing the above-described pigment in a suitable solvent together with a binder resin, if necessary, using a ball mill, attritor, sand mill, ultrasonic wave, or the like, and coating this on the conductive support 1. And formed by drying.

Examples of the binder resin include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, and polyvinyl benzine. Saar, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, and the like.
The amount of the binder resin is preferably 0 to 500 parts by weight and more preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generation material.

Examples of the solvent used in the charge generation layer include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin. , Etc.
Examples of the method for applying the charge generation layer in the previous period include dip coating, spray coating, beat coating, nozzle coating, spinner coating, and ring coating.
The thickness of the charge generation layer is preferably from 0.01 to 5 μm, more preferably from 0.1 to 2 μm.

<Charge transport layer>
The charge transport layer can be formed by dissolving or dispersing a charge transport material and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
The charge transport material includes a hole transport material and an electron transport material.
The hole transport material is not particularly limited and can be appropriately selected from commonly used materials. For example, poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethyl glutamate and its Derivatives, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenyl Stilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene Examples include ene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like. These charge transport materials may be used alone or in combination of two or more.

  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 -Electron-accepting substances such as trinitrodibenzothiophene-5,5-dioxide, benzoquinone derivatives and the like.

  Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polyacetic acid. Vinyl, polyvinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resin and alkyd resin.

The amount of the charge transport material is preferably 20 to 300 parts by weight and more preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.
The thickness of the charge transport layer is preferably 5 to 100 μm.
Examples of the solvent used for the charge transport layer include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone, and the like. Among these, a non-halogen solvent is preferable for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane, and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

For the charge transport layer, a polymer charge transport material having a function as a charge transport material and a function as a binder resin is also preferably used.
As the polymer charge transporting material, a commonly used material can be appropriately selected and used. For example, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the following structural formulas (I) to (X) are particularly preferably used.

However, in said structural formula (I), R < ₁ >, R < ₂ >, R < ₃ > is respectively independently a substituted or unsubstituted alkyl group or a halogen atom, R < ₄ > is a hydrogen atom or a substituted or unsubstituted alkyl group, R < ₅ > , R ₆ is a substituted or unsubstituted aryl group, o, p, q are each independently an integer of 0-4, k, j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0. 9, n represents the number of repeating units and is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formulas (Ia) and (Ib). In the structural formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in said general formula (Ia), R _<101> , R _<102> represents a substituted or unsubstituted alkyl group, an aryl group, or a halogen atom each independently. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or a group represented by formula (Ib).

In the general formula (Ib), a is an integer of 1 to 20, b is an integer of 1 - _2000, R _{103, R 104} represents a substituted or unsubstituted alkyl group or an aryl group. Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different.

However, in Structural Formula (II), R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the structural formula (I). In the structural formula (II), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (III), R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ , and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the structural formula (I). In the structural formula (III), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In Structural Formula (IV), R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as in the structural formula (I). In the structural formula (IV), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (V), R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, and X ₁ and X ₂ are substituted or unsubstituted ethylene. Represents a group or a substituted or unsubstituted vinylene group. X, k, j and n are the same as in the structural formula (I). In the structural formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (VI), R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ and Y _{3 each} represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, May be different. X, k, j and n are the same as those in the structural formula (I). In the structural formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (VII), R ₁₉ and R _{20 each} represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of structural formula (I). In the structural formula (VII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In Structural Formula (VIII), R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the structural formula (I). In the structural formula (VIII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (XI), R ₂₂ , R ₂₃ , R ₂₄ , and R ₂₅ are substituted or unsubstituted aryl groups, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , and Ar ₂₈ are the same or different arylene groups. To express. X, k, j and n are the same as in the structural formula (I). In the structural formula (IX), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

However, in Structural Formula (X), R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ , and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as in the case of structural formula (I). In the structural formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

  As the polymer charge transport material, in addition to the above-mentioned materials, in the state of a monomer or oligomer having an electron donating group at the time of film formation of the charge transport layer, a curing reaction or a crosslinking reaction is performed after the film formation, Finally, a polymer having a two-dimensional or three-dimensional crosslinked structure can also be included.

  The polymer having the crosslinked structure is excellent in wear resistance. Usually, in the electrophotographic process, since the charged potential (unexposed portion potential) is constant, if the surface layer of the electrostatic latent image carrier is worn by repeated use, the electric field applied to the electrostatic latent image carrier by that amount. Strength becomes high. As the electric field strength increases, the occurrence frequency of scumming increases, so that the electrostatic latent image carrier has high wear resistance is advantageous against scumming. The charge transport layer composed of a polymer having these electron donating groups is a polymer compound, so it has excellent film-forming properties and has a charge transport site compared to a charge transport layer composed of a low molecular weight dispersed polymer. It can be configured with high density and has excellent charge transport capability. For this reason, the electrostatic latent image carrier having a charge transport layer using a polymer charge transport material can be expected to have high-speed response.

  Examples of the polymer having a crosslinked structure include a monomer copolymer, a block polymer, a graft polymer, a star polymer, JP-A-3-109460, JP-A-2000-206723, and JP-A-2000. It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-206723.

A plasticizer or a leveling agent may be added to the charge transport layer.
As said plasticizer, what is normally used as a plasticizer of resin can be selected suitably, for example, a dibutyl phthalate, a dioctyl phthalate, etc. are mentioned.
The addition amount of the plasticizer is preferably 30% by mass or less with respect to the binder resin.
Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain.
The addition amount of the leveling agent is preferably less than different mass% with respect to the binder resin.

<Others>
Up to this point, the photosensitive layer has been particularly described with respect to the laminated structure. However, in the present invention, the photosensitive layer may have a single layer structure. In order to make the photosensitive layer into a single layer, the photosensitive layer is formed by providing a single layer containing at least the above-described charge generating substance (a titanyl phthalocyanine crystal having a specific crystal type and a specific particle size) and a binder resin. The layer is constituted, and the materials mentioned in the explanation of the charge generation layer and the charge transport layer are preferably used as the binder resin. In addition, when a single layer photosensitive layer is used in combination with a charge transporting substance, high photosensitivity, high charge transportability, and low residual potential are expressed, which can be suitably used. At this time, as the charge transport material to be used, either a hole transport material or an electron transport material is selected according to the polarity charged on the surface of the electrostatic latent image carrier. Furthermore, since the above-described polymer charge transport material also has the functions of a binder resin and a charge transport material, it is preferably used for a single-layer photosensitive layer.

--Protective layer--
The electrostatic latent image carrier may be provided with a protective layer on the photosensitive layer for the purpose of protecting the photosensitive layer. In recent years, computers have been used on a daily basis, and there has been a demand for miniaturization of devices as well as high-speed output by printers. Therefore, by providing the protective layer and improving the durability, it is possible to obtain an electrostatic latent image carrier having high sensitivity and no abnormal defects.

  As a structure of the said protective layer, the structure which added the filler in binder resin and the structure which uses a bridge type binder are mentioned.

First, a configuration in which a filler is added to the binder resin will be described.
Examples of the material used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, and polyallyl. Sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, Examples thereof include polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. Among these, polycarbonate and polyacrylate are particularly preferable.

In addition to the protective layer, for the purpose of improving wear resistance, for example, fluorine resins such as polytetrafluoroethylene, silicone resins, and those in which inorganic fillers and organic fillers are dispersed in these resins, etc. Can be mentioned.
Examples of the inorganic filler include metal powders such as copper, tin, aluminum, and indium, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, and tin. And metal oxides such as indium oxide, potassium titanate, and the like.
Examples of the organic filler include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like.
Among these, from the viewpoint of filler hardness, an inorganic filler is preferable, and silica, titanium oxide, and alumina are more preferable.

The filler concentration varies depending on the type of filler used and also on the process conditions using the electrostatic latent image carrier. -50 mass% is more preferable, and 10-30 mass% is the most preferable.
Moreover, as an average particle diameter of the said filler, the range of 0.1-2 micrometers is preferable, and the range which is 0.3-1 micrometer is more preferable. At this time, if the average particle diameter is too small, the wear resistance may not be sufficiently exhibited, and if it is too large, the surface property of the coating film may be deteriorated or the coating film itself may not be formed.

  The average particle diameter of the filler in the present invention is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.) unless otherwise specified. At this time, the particle diameter (Median system) corresponding to 50% of the cumulative distribution is calculated. Moreover, it is preferable that the standard deviation of each particle | grain simultaneously measured is 1 micrometer or less. If the standard deviation is larger than this, the particle size distribution is too wide, and the effects of the present invention may not be obtained remarkably.

  The pH of the filler also greatly affects the resolution and the dispersibility of the filler. One possible reason is that hydrochloric acid or the like remains in the filler, particularly the metal oxide, during production. When the residual amount is large, the occurrence of image blur is unavoidable, and depending on the residual amount, the dispersibility of the filler may be affected.

  Another reason is due to the difference in chargeability on the surface of the filler, particularly the metal oxide. Usually, particles dispersed in a liquid are charged positively or negatively, and ions having opposite charges gather to try to keep it electrically neutral, and an electric double layer is formed there. The dispersed state of the particles is stabilized. The potential (zeta potential) gradually decreases with increasing distance from the particle, and the potential in a region that is sufficiently away from the particle and electrically neutral is zero. Therefore, the stability increases as the repulsive force of the particles increases due to an increase in the absolute value of the zeta potential, and the particles tend to aggregate and become unstable as they approach zero. On the other hand, the zeta potential varies greatly depending on the pH value of the system, and at a certain pH value, the potential becomes zero and has an isoelectric point. Therefore, the dispersion system is stabilized by increasing the absolute value of the zeta potential as far as possible from the isoelectric point of the system.

  As the pH with the filler, the pH of the isoelectric point is preferably 5 or more from the viewpoint of image blur suppression, and more preferably more basic. A filler exhibiting basicity having a high pH at the isoelectric point has a higher zeta potential when the system is acidic, thereby improving dispersibility and its stability.

The pH of the filler was determined from the zeta potential at the isoelectric point. At this time, the zeta potential was measured with a laser zeta potentiometer manufactured by Otsuka Electronics Co., Ltd.
Furthermore, as the filler that is less likely to cause image blurring, a filler having high electrical insulation (specific resistance is 10 ¹⁰ Ω · cm or more) is preferable. Those showing 5 or more are particularly preferred.
These may be used singly or in combination of two or more.
Among these fillers, α-type alumina, which is a hexagonal close-packed structure with high insulation, high thermal stability and high wear resistance, is particularly useful in terms of suppressing image blur and improving wear resistance. It is.

As a method for measuring the specific resistance value of the filler, since the resistance value of the powder such as the filler differs depending on the filling rate, it is preferable to measure under a certain condition. Therefore, it measured as follows.
The specific resistance value of the filler was measured using an apparatus having the same configuration as the measuring apparatus shown in FIG. 1 of JP-A-5-113688, and this value was used. In the measuring device, the electrode area is 4.0 cm ² . Prior to the measurement, a load of 4 kg is applied to the electrode on one side for 1 minute, and the sample amount is adjusted so that the distance between the electrodes is 4 mm. At the time of measurement, the measurement is performed with the upper electrode weight (1 kg) loaded, and the applied voltage is measured at 100V. The area of 10 ⁶ Ω · cm or higher was measured with a HIGH RESISTER METER (manufactured by Yokogawa Hewlett Packard), and the area below it was measured with a digital multimeter (manufactured by Fluke).

  The dielectric constant of the filler was determined by measuring the capacitance after applying a load using the same apparatus as that for measuring the specific resistance value. For the measurement of the capacitance, a dielectric measuring device (manufactured by Ando Electric Co., Ltd.) was used.

It is preferable from the viewpoint of dispersibility of the filler that the filler is further surface-treated with at least one surface treatment agent. Lowering the dispersibility of the filler not only increases the residual potential, but also lowers the transparency of the coating, causes defects in the coating, and lowers the wear resistance. It can develop into a big problem.
As the surface treatment agent, a conventionally used surface treatment agent can be appropriately selected and used, but those capable of maintaining the insulating properties of the filler are preferable. For example, titanate coupling agents, aluminum couplings Agents, zircoaluminate coupling agents, higher fatty acids, silane coupling agents, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , silicone, aluminum stearate, and the like are preferable from the viewpoint of filler dispersibility and image blur. It is done. These may be used individually by 1 type and may be used in mixture of 2 or more types.
The addition amount of the surface treatment agent varies depending on the average primary particle diameter of the filler used, but is preferably 3 to 30% by mass, more preferably 5 to 20% by mass. When the addition amount is less than 3% by mass, the filler dispersion effect cannot be obtained, and when it exceeds 30% by mass, the residual potential is significantly increased.
The filler can be dispersed by using an appropriate disperser. Further, from the viewpoint of the transmittance of the protective layer, it is preferable that the filler used is dispersed to the primary particle level and has less aggregates.

The protective layer may contain a charge transport material for reducing residual potential and improving responsiveness.
As the charge transport material, for example, the materials described in the section of the photosensitive layer can be used. When a low molecular charge transport material is used as the charge transport material, a concentration gradient in the protective layer may be provided. In order to improve wear resistance, it is an effective means to reduce the concentration of the surface side. Here, the concentration represents the ratio of the weight of the low-molecular charge transport material to the total weight of all the materials constituting the protective layer, and the concentration gradient is a gradient that decreases the concentration on the surface side in the weight ratio. It shows that it is provided. The use of a polymer charge transport material is very preferable from the viewpoint of enhancing the durability of the electrostatic latent image carrier.

  As the binder resin used in the protective layer, for example, the polymer charge transport material described in the section of the photosensitive layer can be used. By using the polymer charge transporting material as a binder resin, it is possible to improve wear resistance and the like, similarly to the effects described in the section of the photosensitive layer.

Examples of the method for forming the protective layer include commonly used coating methods.
As a film thickness of the said protective layer, 0.1-10 micrometers is preferable.

Next, a protective layer having a crosslinked structure will be described (hereinafter referred to as a crosslinked protective layer).
Regarding the formation of the cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used, and a cross-linking reaction is caused using light or heat energy to form a three-dimensional network structure. This network structure functions as a binder resin and exhibits high wear resistance.

As the reactive monomer, it is preferable to use a monomer having a charge transporting ability in whole or in part.
Suitable examples of the monomer having charge transporting ability include reactive monomers having a triarylamine structure. By using such a monomer, a charge transporting site is formed in the network structure, and the function as a protective layer can be sufficiently expressed.
In addition, the protective layer having such a network structure has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it is too thick, cracks may occur. Therefore, in order to prevent this, even if a protective layer is formed in a laminated structure, a protective layer of a low molecular dispersion polymer is used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure is formed on the upper layer (surface side). good.

  Among the cross-linked protective layers, in particular, a protective layer having a cross-linked structure obtained by curing a tri- or higher functional radical polymerizable monomer has developed a three-dimensional network structure, and has a high hardness and high elasticity with a very high cross-linking density. From the viewpoint of obtaining a surface layer, uniform and high smoothness, and achieving high wear resistance and scratch resistance, it is preferably used.

On the other hand, it is important to increase the crosslink density on the surface of the electrostatic latent image carrier, that is, the number of crosslinks per unit volume as described above, but in order to form a large number of bonds instantaneously in the curing reaction, Stress is generated. This internal stress increases as the thickness of the crosslinkable protective layer increases. Therefore, when the entire protective layer is cured, cracks and film peeling tend to occur. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the process and the effects of charging, development, transfer, cleaning hazards and thermal fluctuations.
As a method for solving this problem, for example, (1) a method of introducing a polymer component into a crosslinked layer and a crosslinked structure, (2) a method of using a large amount of monofunctional and bifunctional radically polymerizable monomers, (3) Although the method of softening the cured resin layer, such as a method using a polyfunctional monomer having a flexible group, can be mentioned, all of them have a low cross-linking density of the cross-linked layer, and a dramatic wear resistance is not achieved. On the other hand, the electrostatic latent image carrier is provided with a crosslinkable protective layer having a high crosslink density in which a three-dimensional network structure is developed on the charge transport layer, so that the above cracks and film peeling do not occur, And very high wear resistance is achieved.
The film thickness of the cross-linked protective layer is preferably 1 to 10 μm, and more preferably 2 to 8 μm from the viewpoint of further preventing the above problem and further improving the wear resistance.

  The reason why the electrostatic latent image bearing member can suppress cracks and film peeling is that the cross-linkable protective layer can be made thin, so that the internal stress does not increase, and since the lower layer has a photosensitive layer or a charge transport layer, the surface is cross-linked. This is because the internal stress of the protective layer can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the crosslinkable protective layer, and the polymer material and radical polymerizable composition (radically polymerizable monomer or radical polymerizable compound having a charge transporting structure) generated at this time are generated. Scratches and toner filming due to incompatibility with the cured product resulting from the reaction are less likely to occur. Further, when the thick film over the entire protective layer is cured by irradiation with light energy, the light transmission from the absorption by the charge transporting structure is limited, and the curing reaction may not sufficiently proceed. In the crosslinkable protective layer of the present invention, preferably a thin film having a thickness of 10 μm or less causes a uniform curing reaction to proceed to the inside, and high wear resistance is maintained inside as well as the surface. In addition, in the formation of the crosslinkable protective layer of the present invention, in addition to the trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is contained, which is the trifunctional or higher functional group. These radically polymerizable monomers are incorporated into the cross-linking during curing. On the other hand, when a low molecular charge transport material having no functional group is contained in the cross-linked surface layer, precipitation of the low molecular charge transport material and white turbidity occur due to its low compatibility, and the cross-linked surface layer The mechanical strength also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the crosslinked protective layer.

  Furthermore, the latent electrostatic image bearing member has good electrical characteristics, and is therefore excellent in repetitive stability, realizing high durability and high stability. This is because a radical polymerizable compound having a monofunctional charge transporting structure is used as a constituent material of the crosslinkable protective layer and is immobilized in a pendant shape between the crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and the electrical characteristics are remarkably deteriorated in repeated use such as reduction in sensitivity and increase in residual potential. When a bifunctional or higher-functional charge transporting compound is used as the main component, it is fixed in the crosslinked structure with a plurality of bonds, so the intermediate structure (cation radical) during charge transport cannot be kept stable, Sensitivity decreases due to traps and residual potential increases. Such deterioration of the electric characteristics appears as an image such as a decrease in image density and thinning of characters. Furthermore, in the electrostatic latent image carrier, a high mobility design with less charge trapping of the conventional electrostatic latent image carrier can be applied as a lower charge transport layer, and the electrical side effects of the crosslinked protective layer are minimized. To the limit.

  Furthermore, in the formation of the above-mentioned crosslinkable protective layer of the present invention, the drastic wear resistance is exhibited particularly by making the crosslinkable protective layer insoluble in the organic solvent. The crosslinked protective layer of the present invention is formed by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Dimensional network structure develops and has a high crosslinking density, but contains other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives and lower layers) Depending on the dissolved components) and curing conditions, the cross-linking density may be locally dilute or may be formed as an aggregate of minute cured products cross-linked at high density. Such a crosslinkable protective layer has a low bonding strength between cured products and is soluble in organic solvents, and is repeatedly used in the electrophotographic process. Detachment easily occurs. By making the cross-linkable protective layer insoluble in an organic solvent as in the present invention, the original three-dimensional network structure is developed and has a high degree of cross-linking, and the chain reaction proceeds in a wide range so that a cured product is obtained. Due to the high molecular weight, a dramatic improvement in wear resistance is achieved.

Examples of the trifunctional or higher functional monomer having no charge transporting structure include a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, condensed polycyclic quinone, diphenoquinone, cyano group, nitro group, and the like. A monomer having no electron transport structure such as an electron-withdrawing aromatic ring and having three or more radically polymerizable functional groups.
The radical polymerizable functional group can be appropriately selected and used as long as it has a carbon-carbon double bond and can be radically polymerized.
Examples of the radical polymerizable functional group include a 1-substituted ethylene functional group and a 1,1-substituted ethylene functional group shown below.

Examples of the 1-substituted ethylene functional group include functional groups represented by the following general formula.
(General formula)
CH ₂ = CH-X ₁ -
However, in said general formula, X < ₁ > is arylene groups, such as phenylene group which may have a substituent, a naphthylene group, an alkenylene group which may have a substituent, -CO- group, -COO-. group, -CON (R ₁₀₎ - group (R ₁₀ is hydrogen, alkyl group such as a methyl group, an ethyl group, a benzyl group, naphthylmethyl group, an aralkyl group such as a phenethyl group, a phenyl group, an aryl group such as phenyl or naphthyl Or -S- group.
Specific examples of the functional group include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamide group, vinylthioether group, and the like.

Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following general formula.
(General formula)
_{CH 2 = C (Y) -X} 2 -
However, in the general formula, Y represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, a naphthyl group, etc. An aryl group, a halogen atom, a cyano group, a nitro group, a methoxy group, an ethoxy group or other alkoxy group, a —COOR ₁₁ group (R ₁₁ is a hydrogen atom, an optionally substituted methyl group, an ethyl group, etc. An alkyl group, an aralkyl group such as an optionally substituted benzyl or phenethyl group, an aryl group such as an optionally substituted phenyl group or naphthyl group, or a -CONR ₁₂ R ₁₃ group (R ₁₂ And R ₁₃ represents a hydrogen atom, an alkyl group such as an optionally substituted methyl group or an ethyl group, an aralkyl group such as an optionally substituted benzyl group, naphthylmethyl group, or phenethyl group. Or Represents an aryl group such as a phenyl group and a naphthyl group which may have a substituent, and may be the same or different from each other.) X ₂ is the same substituent as X _{1 in the} above formula 10 And a single bond and an alkylene group, provided that at least one of Y and X ₂ is at least an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring.
Specific examples of the functional group include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
Examples of the substituent further substituted with the substituent for X ₁ , X ₂ and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as an ethyl group, a methoxy group, an ethoxy group, and the like. Examples thereof include aryloxy groups such as alkoxy groups and phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, aralkyl groups such as benzyl groups and phenethyl groups.

  Among these radical polymerizable functional groups, an acryloyloxy group and a methacryloyloxy group are particularly preferable, and a compound having three or more acryloyloxy groups includes, for example, a compound having three or more hydroxyl groups in the molecule and acrylic acid ( Salt), an acrylic acid halide, and an acrylic ester, and an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

  As a specific tri- or more functional radical polymerizable monomer having no charge transport structure, a commonly used substance can be appropriately selected and used. For example, trimethylolpropane triacrylate (TMPTA), trimethylol Methylolpropane trimethacrylate, trimethylolpropane alkylene modified triacrylate, trimethylolpropane ethyleneoxy modified (hereinafter EO modified) triacrylate, trimethylolpropane propyleneoxy modified (hereinafter PO modified) triacrylate, trimethylolpropane caprolactone modified triacrylate, tri Methylolpropane alkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol, epichlorohydrin modified (hereinafter ECH modified) triacrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone Modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, Phosphoric acid EO-modified triacrylate, 2,2, , 5, - tetramethyl-hydroxymethyl cyclopentanone tetraacrylate, and the like. These may be used individually by 1 type and may combine 2 or more types.

The trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure has a ratio of molecular weight to the number of functional groups in the monomer (molecular weight / number of functional groups) in order to form dense crosslinks in the crosslinkable protective layer. ) Is preferably 250 or less. If this ratio is greater than 250, the cross-linked protective layer is soft and wear resistance may be somewhat lowered. Therefore, among the monomers exemplified above, monomers having a modifying group such as EO, PO, caprolactone, etc. It may be difficult to use a compound having a long modifying group alone.
The proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure is preferably 20 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the crosslinked protective layer. When the component ratio is less than 20% by mass, the three-dimensional crosslink density of the crosslinkable protective layer is small, and it may be difficult to achieve a dramatic improvement in wear resistance as compared with the case of using a conventional thermoplastic binder resin. On the other hand, when it exceeds 80% by mass, the content of the charge transporting compound is lowered, and the electrical characteristics may be deteriorated. The electrical properties and abrasion resistance required vary depending on the process used, and the thickness of the crosslinked protective layer of the electrostatic latent image carrier varies accordingly. The range of 30-70 mass% is the most preferable.

Examples of the radical polymerizable compound having a monofunctional charge transporting structure include a hole transporting structure such as triarylamine, hydrazone, pyrazoline, and carbazole, a condensed polycyclic quinone, diphenoquinone, a cyano group, and a nitro group. It refers to a compound having an electron transport structure such as an electron-withdrawing aromatic ring and having one radical polymerizable functional group.
Examples of the radical polymerizable functional group include those described above for the radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly preferable.
Further, as the charge transporting structure, a triarylamine structure is preferable, and in particular, a compound represented by the following structural formula (1) or (2) is preferable because electrical characteristics such as sensitivity and residual potential are favorably sustained. .

In the Structural Formula (1) and (2), R ₁ has a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, a substituent Aryl group, cyano group, nitro group, alkoxy group, —COOR ₇ (wherein R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group or a substituent which may have a substituent) Aryl group which may have a group), carbonyl halide group or CONR ₈ R ₉ (wherein R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, or a substituent. Represents an aralkyl group which may be substituted or an aryl group which may have a substituent, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group. The same May be different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3.

In the structural formulas (1) and (2), examples of the alkyl group in the substituent of R ₁ include a methyl group, an ethyl group, and a propyl group. Examples of the alkoxy group include a methoxy group, An ethoxy group, a propoxy group, etc. are mentioned. These include halogen atoms, nitro groups, cyano groups, alkyl groups such as methyl groups and ethyl groups, alkoxy groups such as methoxy groups and ethoxy groups, aryloxy groups such as phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, It may be substituted with an aralkyl group such as a benzyl group or a phenethyl group.
Among the substituents for R ₁ , a hydrogen atom and a methyl group are preferable.

Examples of the aryl group of Ar ₃ and Ar ₄ include a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group.
As the condensed polycyclic hydrocarbon group, those having 18 or less carbon atoms forming a ring are preferable. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , Chrycenyl group, naphthacenyl group, and the like.
Examples of the non-condensed cyclic hydrocarbon group include monovalent hydrocarbon monovalent groups such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane and polyphenylalkene, and ring-assembled hydrocarbons such as 9,9-diphenylfluorene The monovalent group of a compound is mentioned.
Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

Moreover, the aryl group represented by Ar3 and Ar4 may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group, etc.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, and these alkyl groups further contain fluorine atoms , a hydroxyl group, a cyano group, an alkoxy group of C ₁ -C _4, a phenyl group or a halogen atom, which may have a phenyl group substituted by an alkoxy group C ₁ -C ₄ alkyl or C ₁ -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxy Examples include ethyl group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group, and the like.
(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group , A trifluoromethoxy group, and the like.
(4) an aryloxy group, phenyl and the aryl group group, a naphthyl group, an alkoxy group of C ₁ -C _4, alkyl group of C ₁ -C _4, also contain a halogen atom as a substituent Good. Specific examples include phenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, 4-methoxyphenoxy group, 4-methylphenoxy group, and the like.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group, and the like.
(6) Group represented by the following general formula
However, in said general formula, R < ₃ > and R < ₄ > represents a hydrogen atom, an alkyl group, or an aryl group each independently. Examples of the aryl group include a phenyl group, biphenyl group or a naphthyl group and the like, also contain these alkoxy groups C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent Good. R ₃ and R ₄ may form a ring together.
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group , A pyrrolidino group, and the like.
(7) An alkylenedioxy group such as a methylenedioxy group or an alkylenedithio group such as 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 substituted or unsubstituted alkylene group of X include C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , and more preferably C _{1 to} C ₄ linear or branched alkylene groups. a fluorine atom in the alkylene group, a hydroxyl group, a cyano group, C ₁ -C ₄ alkoxy group, a phenyl group or a halogen atom, phenyl substituted with alkyl group or a C ₁ -C ₄ alkoxy group C ₁ -C ₄ It may have a group.
Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxy. Examples include ethylene group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group, and the like.

Examples of the substituted or unsubstituted cycloalkylene group include C _{5 to} C ₇ cyclic alkylene groups, and these cyclic alkylene groups include fluorine atom, hydroxyl group, C _{1 to} C ₄ alkyl group, and C _{1 to} C 4. _It may have ₄ alkoxy groups.
Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
Examples of the substituted or unsubstituted alkylene ether group include ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, and substituents such as a hydroxyl group, a methyl group, and an ethyl group. You may have.

The vinylene group is represented by the following general formula.
In the general formula, R ₅ is hydrogen, an alkyl group (the (same as alkyl group, as defined 2)), an aryl group (said Ar _3, the same as the aryl group represented by Ar _4), a is 1 or 2, b represents 1-3.

Examples of Z include a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, and an alkyleneoxycarbonyl divalent group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether divalent group include the alkylene ether divalent group of X.
Examples of the alkyleneoxycarbonyl divalent group include a caprolactone divalent modifying group.

Furthermore, preferred examples of the radical polymerizable compound having a monofunctional charge transporting structure include compounds represented by the following structural formula (3).
However, in the structural formula (3), o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, and Rb and Rc are substituents other than a hydrogen atom and have 1 to 6 carbon atoms. Represents an alkyl group, and a plurality of them may be different. s and t represent an integer of 0 to 3. Za represents a single bond, a methylene group, an ethylene group, or a group represented by the following general formula (4).

  The compound represented by the general formula (4) is preferably a compound having at least one of a methyl group and an ethyl group as a substituent for Rb and Rc.

  Since the radically polymerizable compound having the monofunctional charge transporting structure represented by the structural formulas (1) to (3), particularly (3), is polymerized because the carbon-carbon double bond is opened on both sides, In a polymer that does not become a terminal structure, is incorporated in a chain polymer, and is crosslinked by polymerization with a radically polymerizable monomer having three or more functions, it exists in the main chain of the polymer, and the main chain- Present in the cross-linked chain between the main chains (this cross-linked chain includes an inter-molecular cross-linked chain between one polymer and another polymer, a site with a main chain folded in one polymer, and a main chain. There are intramolecular cross-linked chains that are cross-linked with other sites derived from the polymerized monomer at positions away from this in the chain), but they are also present in the cross-linked chain even if they are present in the main chain Even if the triarylamine structure suspended from the chain moiety is Has at least three aryl groups arranged in the bulky and is bulky, but is not directly bonded to the chain part, but is suspended from the chain part via a carbonyl group etc. Since these triarylamine structures can be arranged in the polymer in a space that is reasonably adjacent to each other, there is little structural distortion in the molecule, and the electrophotographic electrostatic latent image carrier In the case of a surface layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.

Specific examples of the radical polymerizable compound having the monofunctional charge transporting structure are shown below, but are not limited to the compounds having these structures.

The radically polymerizable compound having the monofunctional charge transporting structure is important for imparting the charge transporting performance of the crosslinked protective layer.
The content of this component is preferably 20 to 80% by mass with respect to the crosslinkable protective layer, and the required electric characteristics and wear resistance differ depending on the process used. Since the thickness of the cross-linked protective layer of the body is also different, it cannot be generally stated, but 30 to 70% by mass is more preferable in consideration of the balance of both characteristics. If this component is less than 20% by mass, the charge transport performance of the crosslinkable protective layer cannot be maintained sufficiently, and repeated use may cause deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential. On the other hand, when it exceeds 80% by mass, the content of the trifunctional monomer having no charge transporting structure is lowered, and the crosslink density is lowered, so that high wear resistance may not be exhibited.

  The crosslinked protective layer is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radically polymerizable oligomers are used in combination for the purpose of imparting functions such as viscosity adjustment at the time, stress relaxation of the cross-linkable protective layer, low surface energy and friction coefficient reduction. be able to. As these radically polymerizable monomers and oligomers, commonly known monomers can be used.

  Examples of the monofunctional radical monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, and cyclohexyl. Examples include acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and styrene monomer.

  Examples of the bifunctional radically polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1 , 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.

  Examples of the functional monomer include those substituted with fluorine atoms such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, and the like. No. 60503, JP-B-6-45770, acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane having 20 to 70 siloxane repeating units Examples thereof include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.

  Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.

  The content of these monomers and oligomers is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of a tri- or higher functional radical polymerizable monomer. If the content exceeds 50 parts by weight, the three-dimensional cross-linking density of the cross-linking protective layer may be substantially reduced, leading to a decrease in wear resistance.

  The crosslinkable protective layer may contain a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator in the crosslinkable protective layer coating liquid in order to efficiently advance the curing reaction as necessary. good.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5. -Di (peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butyl Peroxycyclohexyl) propane and other peroxide initiators, azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid An azo-based initiator such as

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 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 Acetophenone-based or ketal-based photopolymerization of 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobu Benzoin ether photopolymerization initiators such as ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone-based photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthone such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, etc. -Based photopolymerization initiator, ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine Oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, Other photopolymerization initiators such as acridine compounds, triazine compounds, and imidazole compounds can be mentioned.
Moreover, the substance which has a photopolymerization acceleration effect can also be used.
Examples of the substance having an effect of promoting photopolymerization include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4 ′. -Dimethylaminobenzophenone, etc. These may be used alone or in combination with the photopolymerization initiator.

The said polymerization initiator may be used individually by 1 type, and may mix and use 2 or more types.
As content of the said polymerization initiator, it is preferable that it is 0.5-40 weight part with respect to 100 weight part of total content which has radical polymerizability, and it is more preferable that it is 1-20 weight part.

Furthermore, the crosslinkable protective layer includes, as necessary, a plasticizer (for the purpose of stress relaxation and adhesion improvement), a leveling agent, a low molecular charge substance having no radical reactivity, and the like. These additives may be included.
These additives can be appropriately selected from commonly used substances, and examples of the plasticizer include dibutyl phthalate and dioctyl phthalate. Examples of the leveling agent include: , Silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain, and the like.
As content of the said plasticizer, it is preferable that it is 20 mass% or less with respect to the total solid of a coating liquid, and it is more preferable that it is 10 mass% or less. As content of the said leveling agent, it is preferable that it is 3 mass% or less with respect to the total solid of a coating liquid.

The crosslinkable protective layer comprises a coating solution containing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Or it forms by apply | coating and hardening | curing on a charge transport layer. When the radically polymerizable monomer is a liquid, the coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied.
Examples of the solvent include 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, tetrahydrofuran, dioxane and propyl ether. Ethers, halogens such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.
There is no restriction | limiting in particular as a dilution rate with the said solvent, According to the solubility of a composition, the coating method, and the target film thickness, it can change suitably.
As the application, for example, a dip coating method, spray coating, bead coating, ring coating method, or the like can be used.

The pre-crosslinked protective layer is formed by applying a crosslinkable protective layer coating solution, and then applying and curing energy from the outside. Examples of the external energy include heat, light, and radiation.
Examples of the method of applying heat energy include a method of heating 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, 100 degreeC or more is preferable and 170 degreeC or less is more preferable. Below 100 ° C., the reaction rate is slow and the curing reaction may not be completed completely. At a high temperature exceeding 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals may be generated in the crosslinked protective layer. In order to advance the curing reaction uniformly, a method of heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more to complete the reaction is also preferable.
Examples of the energy of light include UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps mainly having an emission wavelength in the ultraviolet region, but the visible light source can be used in accordance with the absorption wavelength of radical polymerizable substances and photopolymerization initiators. Selection is also possible.
As irradiation light quantity, 50-1000 mW / cm < ² > or less is preferable. Is less than 50 mW / cm ² may take time for the curing reaction, 1000 mW / progression of stronger reaction than cm ² becomes non-uniform, local wrinkles may occur in the crosslinked protective layer surface, a large number of unreacted Residues, reaction termination ends may occur. In addition, the internal stress increases due to rapid crosslinking, which may cause cracks and film peeling.
Examples of radiation energy include those using electron beams.
Among these energies, it is preferable to use heat or light energy because of easy reaction rate control and simple apparatus.

  The thickness of the crosslinkable protective layer is preferably 1 to 10 μm or less, and more preferably 2 to 8 μm or less. If it is thicker than 10 μm, cracks and film peeling may easily occur. When the thickness is 8 μm or less, the margin is further improved, so that the crosslinking density can be increased, and further, material selection and setting of curing conditions can be set to enhance wear resistance. On the other hand, the radical polymerization reaction is susceptible to oxygen inhibition, that is, the surface in contact with the air may not be cross-linked or become uneven due to the influence of radical trapping by oxygen. This effect appears remarkably when the surface layer is less than 1 μm, and the crosslinkable protective layer having a thickness less than this thickness may cause a decrease in wear resistance or uneven wear. In addition, when the crosslinkable protective layer is applied, the lower charge transport layer component is mixed.In particular, if the coating thickness of the crosslinkable protective layer is thin, the contaminants spread throughout the layer, inhibiting the curing reaction and reducing the crosslink density. May cause reduction. For these reasons, the crosslinkable protective layer of the present invention has a good abrasion resistance and scratch resistance at a film thickness of 1 μm or more, but if it can be locally scraped to the lower charge transport layer in repeated use, The wear of the portion increases, and the density unevenness of the halftone image tends to occur due to the charging property and sensitivity fluctuation. Therefore, it is preferable that the film thickness of the crosslinkable protective layer is 2 μm or more for a longer life and higher image quality.

  In the structure in which the charge blocking layer, the moire preventing layer, the photosensitive layer (charge generation layer, charge transport layer), and the crosslinkable protective layer of the electrostatic latent image carrier are sequentially laminated, the outermost crosslinkable protective layer is an organic solvent. On the other hand, when it is insoluble, it is characterized in that dramatic wear resistance and scratch resistance are achieved. As a method for testing the solubility in an organic solvent, one drop of an organic solvent having a high solubility in a polymer substance, for example, tetrahydrofuran, dichloromethane or the like, is dropped on the surface layer of the electrostatic latent image carrier, and is allowed to stand after natural drying. The change of the surface shape of the electrostatic latent image carrier can be determined by observing with a stereomicroscope. The electrostatic latent image carrier with high solubility has a phenomenon that the central part of the droplet becomes concave and the surroundings swell up in reverse, the phenomenon that the charge transport material precipitates and white turbidity or cloudiness occurs due to crystallization, the surface swells and then shrinks There are changes such as the phenomenon of wrinkles. On the other hand, the insoluble electrostatic latent image carrier does not exhibit the above-described phenomenon, and does not change at all as before dropping.

  In the constitution of the present invention, in order to make the crosslinkable protective layer insoluble in the organic solvent, (1) composition of the crosslinkable protective layer coating solution, adjustment of the content ratio thereof, (2) coating of the crosslinkable protective layer Dilution solvent of working solution, adjustment of solid content concentration, (3) Selection of coating method of crosslinkable protective layer, (4) Control of curing conditions of crosslinkable protective layer, (5) Difficult dissolution of lower charge transport layer It is important to control these factors such as sexualization, but it is not achieved by a single factor.

  The composition of the crosslinkable protective layer coating solution may be a radical polymerizable compound in addition to the above-described trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as a binder resin having no functional group, an antioxidant, and a plasticizer is contained, the crosslinking density is reduced, and the cured product resulting from the reaction and phase separation between the additive and the organic solvent are caused. It tends to be soluble. Specifically, it is important to suppress the total content to 20% by mass or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by mass or less based on the trifunctional radical polymerizable monomer. It is preferable. Further, when a large amount of a radical polymerizable compound having a bifunctional or higher functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by mass or less based on the radical polymerizable compound having a monofunctional charge transporting structure.

  As for the diluting solvent of the crosslinkable protective layer coating solution, if a solvent with a slow evaporation rate is used, the remaining solvent may hinder the curing, or increase the amount of the lower layer component mixed. Reduces the cured density. For this reason, it tends to be soluble in organic solvents. Specifically, tetrahydrofuran, a mixed solvent of tetrahydrofuran and methanol, ethyl acetate, methyl ethyl ketone, ethyl cellosolve and the like are useful, but are selected according to the coating method. Moreover, regarding the solid content concentration, if it is too low for the same reason, it tends to be soluble in an organic solvent. Conversely, the upper limit concentration is constrained by the limitations of film thickness and coating solution viscosity. Specifically, it is preferably used in the range of 10 to 50% by mass. As a coating method for the cross-linked protective layer, for the same reason, the solvent content at the time of forming the coating film, a method of reducing the contact time with the solvent is preferable, specifically, the spray coating method, the amount of coating liquid A regulated ring coat method is preferred. Also, in order to suppress the amount of the lower layer component mixed in, a polymer charge transport material is used as the charge transport layer, and a crosslinkable protective layer is applied between the photosensitive layer (or charge transport layer) and the crosslinkable protective layer. It is also effective to provide an intermediate layer insoluble in the solvent.

As curing conditions for the crosslinkable protective layer, if the energy of heating or light irradiation is low, the curing is not completely completed and the solubility in the organic solvent is increased. On the other hand, when cured with very high energy, the curing reaction becomes non-uniform, and it tends to increase the number of uncrosslinked parts and radical stopping parts and to form an aggregate of minute cured products. For this reason, it may become soluble in an organic solvent.
In order to insolubilize in the organic solvent, the thermosetting condition is preferably 100 to 170 ° C., more preferably 10 minutes to 3 hours. The curing conditions by UV light irradiation are preferably 50 to 1000 mW / cm ² , 5 seconds to 5 minutes, and the temperature rise is controlled to 50 ° C. or less to suppress uneven curing reaction.

  An example of a method for making the crosslinked protective layer insoluble in an organic solvent is, for example, using an acrylate monomer having three acryloyloxy groups and a triarylamine compound having one acryloyloxy group as a coating solution. In this case, the ratio of use is 7: 3 to 3: 7, and 3 to 20% by mass of a polymerization initiator is added to the total amount of these acrylate compounds, and a solvent is further added to prepare a coating solution. For example, in the case where the charge transport layer which is the lower layer of the crosslinkable protective layer uses a triarylamine donor as the charge transport material and polycarbonate as the binder resin and the surface layer is formed by spray coating, the above coating liquid As the solvent, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio thereof is 3 to 10 times the total amount of the acrylate compound.

After preparing the coating solution, for example, spray the prepared coating solution on an electrostatic latent image carrier in which an undercoat layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. Apply by etc. Then, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes) and cured by UV irradiation or heating.
In the case of UV irradiation, a metal halide lamp or the like is used, but the illuminance is preferably 50 to 1000 mW / cm ² and the time is preferably 5 seconds to 5 minutes, and the drum temperature is controlled not to exceed 50 ° C. preferable.
In the case of thermosetting, the heating temperature is preferably from 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is preferably from 20 minutes to 3 hours. .
After completion of the curing, the electrostatic latent image carrier of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.

  In addition to the above-described protective layer containing filler and cross-linked protective layer, a commonly known material such as a-C or a-SiC formed by a vacuum thin film forming method should be used as the protective layer. You can also.

  As described above, the use of a polymer charge transporting material for the photosensitive layer (charge transporting layer) or the provision of a protective layer on the surface of the electrostatic latent image bearing member can improve the durability of the electrostatic latent image bearing member ( In addition to improving wear resistance, when used in a tandem type full-color image forming apparatus as described later, a new effect not found in a monochrome image forming apparatus is also produced.

-Others-
In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, in particular, in each layer such as a protective layer, a charge transport layer, a charge generation layer, a charge blocking layer, a moire prevention layer. Antioxidants can be added.
Examples of the antioxidant include phenolic compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, and organic phosphorus compounds.

  Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3 -Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Ben ) Benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3 ′) -T-butylphenyl) butyric acid] cricol ester, tocopherols, and the like.

  Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.

  Examples of the hydroquinones include 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methyl. And hydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone.

  Examples of the organic sulfur compounds include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like. It is done.

  Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics, fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant is preferably 0.01 to 10% by mass with respect to the total weight of the layer to be added.

(Image forming apparatus and toner)
Next, an image forming apparatus and toner in which the image forming method of the present invention is used will be described. A part of the image forming method is also described in this section.
FIG. 7 is a schematic diagram for explaining the image forming apparatus of the present invention, and a modification as shown later also belongs to the category of the present invention.
The electrostatic latent image carrier 1 is as described above.

-Charging member-
The charging member 3 is not particularly limited as long as it can sufficiently charge the electrostatic latent image carrier, and can be appropriately selected and used. For example, a scorotron charging member, A contact type charging member (roller shape), a charging member in which the surface of the electrostatic latent image carrier and the surface of the charging member are arranged close to 100 μm or less, and the like are preferably used. Here, the contact type charging member is a type in which the surface of the charging member is in contact with the surface of the electrostatic latent image carrier in the image forming region. Can also be used.
The non-contact type charging member is used in such a manner that the gap between the surface of the electrostatic latent image carrier and the surface of the charging member is arranged close to each other so as to be 100 μm or less. The gap between the electrostatic latent image carrier and the charging member is preferably 5 to 100 μm, and more preferably 10 to 50 μm. If the gap exceeds 100 μm, the charging tends to become unstable and charging unevenness may occur. If the gap is less than 5 μm, the surface of the charging member may be in the presence of residual toner on the electrostatic latent image carrier. May be contaminated. In the charging member of the non-contact charging method, the electrostatic latent image carrier is not in contact with the electrostatic latent image carrier so that contamination of the electrostatic latent image carrier can be suppressed, and the charging efficiency is high and the amount of ozone generation is small. It has advantages such as being advantageous for downsizing of the apparatus. When priority is given to dot reproducibility for the purpose of high-definition image formation, an electric field strength of 30 V / μm or more is applied to the electrostatic latent image carrier by the charging member as the electric field strength represented by the following formula. The The higher the electric field strength applied to the electrostatic latent image carrier, the better the dot reproducibility, but it may cause problems with dielectric breakdown of the electrostatic latent image carrier and carrier adhesion during development. Is generally preferably 60 V / μm or less, and more preferably 50 V / μm or less.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)

  When charging is performed by a contact method using a roller-shaped charging member, the electrostatic latent image carrier diameter (outer diameter) is preferably not an integral multiple of the roller diameter (outer diameter). When the electrostatic latent image bearing member diameter is an integral multiple of the roller diameter, the surface of the electrostatic latent image bearing member and the roller surface always come into contact with each other in repeated use. There is no particular problem when both are used under normal conditions. However, if a partial defect or the like occurs on the roller surface, it is possible to keep the same electrostatic latent image carrier surface in contact with the electrostatic latent image. The life of the image carrier is significantly reduced. In such a case, if the electrostatic latent image carrier diameter is not an integral multiple of the roller diameter, at least the surfaces are always used out of alignment with each other. Therefore, it is important that the electrostatic latent image carrier diameter is not an integral multiple of the roller diameter.

  Furthermore, as an application method of charging, it is preferable to superimpose an AC voltage because it has an advantage that uneven charging is less likely to occur. In particular, in the tandem type full-color image forming apparatus described later, in addition to the problem of uneven density of a halftone image due to uneven charging that occurs in the case of a monochrome image forming apparatus, there is a serious problem of deterioration in color balance (color reproducibility). Connected. By superimposing the alternating current component on the direct current component, the above problems are greatly improved. However, if the conditions (frequency, peak-to-peak voltage) of the alternating current component are too large, the hazard to the electrostatic latent image carrier is large. Thus, the deterioration of the electrostatic latent image carrier may be accelerated. For this reason, it is preferable to minimize the superposition of alternating current components.

  The frequency of the AC component varies depending on the linear velocity of the electrostatic latent image carrier, but 3 kHz or less, preferably 2 kHz or less is appropriate. When plotting the relationship between the voltage applied to the charging member and the charging potential to the electrostatic latent image carrier, there is a region where the electrostatic latent image carrier is not charged despite voltage application according to Paschen's law. A potential at which charging rises from a certain point is recognized. About twice this rising potential is the optimum potential (usually about 1200 to 1500 V) as the peak-to-peak voltage. However, when the electrostatic latent image bearing member has low charging ability or the linear velocity is very high, the peak-to-peak voltage twice the rising potential as described above may be insufficient. On the other hand, when the chargeability is good, the potential stability may be sufficiently exhibited even when it is twice or less. Therefore, the peak-to-peak voltage is preferably 3 times or less, more preferably 2 times or less of the rising potential. If the peak-to-peak voltage is rewritten as an absolute value, it is preferably used at 3 kV or less, preferably 2 kV or less, more preferably 1.5 kV or less.

-Image exposure section-
As the image exposure unit 5, a light source having a devised optical system capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL) and capable of writing with a beam diameter of 50 μm or less. used. The idea of the optical system is a technique for reducing the writing beam diameter by, for example, a method described in Japanese Patent Application Laid-Open No. 2002-277801. In the present invention, the optical beam can be formed to 50 μm or less. Any method can be used.

Here, the beam diameter will be described. Usually, writing light emitted from an optical element is applied to the surface of the electrostatic latent image carrier through an optical system (mirror or lens). This writing beam does not become a perfect circle, but has a slightly flattened shape like an ellipse, and it is the major axis direction of the ellipse that determines the writing size. Therefore, the beam diameter in the present invention refers to the length of the major axis.
Further, such a beam has a Gaussian distribution from the center of light emission and has a shape described in, for example, FIG. 6 of JP-A-2002-277801. Therefore, the long axis cannot be determined without defining the light intensity, but in the present invention, the definition generally used is used. That is, the major axis of the region where the amount of light is larger than 1 / e ^ 2 of the maximum intensity of the exposure beam is used as the beam diameter of the present invention.

Depending on the resolution of the light source (writing light), the resolution of the formed electrostatic latent image, and thus the toner image, is determined. The higher the resolution, the clearer the image. However, if writing is performed at a higher resolution, writing takes longer, so writing with one writing light source is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 1200 dpi is the upper limit. When there are a plurality of write light sources, each of them only has to bear a write area, and the upper limit is substantially “1200 dpi × number of write light sources”. The writing light source here refers to one LD element or one LED element. For example, LEDs arranged in an array are handled as a plurality of light sources.
Among these light sources, the light emitting diode and the semiconductor laser have high irradiation energy and long wavelength light of 600 to 800 nm. Therefore, the specific crystal type phthalocyanine pigment, which is a charge generation material used in the present invention, It is preferably used because of its high sensitivity.

-Development unit-
The developing unit 6 can handle both normal development and reversal development depending on the charging polarity of the toner used. When toner having a polarity opposite to that of the electrostatic latent image carrier is used, regular development is used. When toner having the same polarity is used, the electrostatic latent image is developed by reversal development. Depending on the light source used in the previous image exposure unit, in the case of a digital light source used in recent years, there is generally a reversal development method in which toner development is performed on the writing portion in response to a low image area ratio. This is advantageous in view of the lifetime of the light source. In addition, there are two methods, a one-component method in which development is performed using only toner and a two-component method in which a two-component developer composed of toner and carrier is used.

  There are also two methods for transferring the toner image formed on the electrostatic latent image carrier onto the transfer paper. One is a method of directly transferring a toner image developed on the surface of an electrostatic latent image carrier as shown in FIG. 7 to a recording medium (for example, transfer paper), and the other is once an electrostatic latent image carrier. In this method, a toner image is transferred from a body to an intermediate transfer body and transferred to a transfer paper. Any of them can be used in the present invention, but in particular, the toner image formed on the surface of the electrostatic latent image carrier is directly transferred directly to a transfer medium (output paper or the like) as a recording medium. A transfer system is preferably used.

-Transfer conveyor belt-
Although a transfer charger and a transfer roller can be used as the transfer conveyance belt 10, it is preferable to use a contact type such as a transfer belt or a transfer roller with a small amount of ozone generation. As a voltage / current application method during transfer, either a constant voltage method or a constant current method can be used. However, the transfer charge amount can be kept constant, and the stability is excellent. The constant current method is more preferable. As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.

  At this time, the surface potential of the electrostatic latent image carrier after transfer has a great influence on the electrostatic fatigue of the electrostatic latent image carrier in repeated use. That is, the electrostatic fatigue of the electrostatic latent image carrier is greatly affected by the amount of charge passing through the electrostatic latent image carrier. This passing charge amount corresponds to the amount of charge flowing in the film thickness direction of the electrostatic latent image carrier. As an operation of the electrostatic latent image carrier in the image forming apparatus, the main charger is charged to a desired charging potential (in most cases, negatively charged), and optical writing is performed based on an input signal corresponding to the document. At this time, photocarriers are generated in the portion where writing is performed, and the surface charge is neutralized (potential decay). At this time, the amount of charge depending on the amount of generated photocarriers flows in the direction of the film thickness of the electrostatic latent image carrier.

  On the other hand, the area where the optical writing is not performed (non-writing portion) proceeds to the charge removal process through the development process and the transfer process (a cleaning process is performed before that if necessary). Here, when the surface potential of the electrostatic latent image carrier is close to the potential applied by the main charging (excluding dark decay), the amount of charge is almost the same as the area where optical writing is performed. The electric latent image carrier flows in the film thickness direction. In general, since the current document has a low writing rate, this method means that most of the passing charge amount of the electrostatic latent image carrier in repeated use is the current flowing in the static elimination process. That is, assuming that the writing rate is 10%, the current flowing in the static elimination process occupies 90% of the total.

  This passing charge greatly affects the electrostatic characteristics of the electrostatic latent image carrier, such as causing deterioration of the material constituting the electrostatic latent image carrier. As a result, the residual potential of the electrostatic latent image carrier is raised, depending on the passing charge amount. If the residual potential of the electrostatic latent image carrier increases, the image density decreases in negative / positive development, which is a serious problem. Therefore, in order to increase the life of the electrostatic latent image carrier in the image forming apparatus, there is a problem of how to reduce the amount of charge passing through the electrostatic latent image carrier.

On the other hand, there is a way of thinking that the photostatic discharge is not performed, but if the main charger is not sufficiently charged, the charging cannot be stabilized and a problem such as an afterimage may occur.
The passage charge of the electrostatic latent image carrier is generated by the movement of the generated optical carrier due to light irradiation by the potential charged on the surface of the electrostatic latent image carrier (the electric field generated thereby). . Therefore, if the surface potential of the electrostatic latent image carrier can be attenuated by means other than light, the passing charge amount per rotation of the electrostatic latent image carrier (one cycle of image formation) can be reduced.

  For this purpose, it is effective to adjust the amount of charge passing through the electrostatic latent image carrier by adjusting the transfer bias in the transfer step. That is, a non-writing portion that is charged by main charging and does not perform writing enters the transfer process in a state close to the charged potential except for the dark attenuation amount. At this time, the absolute value on the polarity side charged by the main charger is reduced to 100 V or less, so that almost no photocarrier is generated even if the subsequent charge removal process is entered, and no passing charge is generated. This value is preferably closer to 0V.

-Light source, etc.-
For the light source such as the static elimination lamp 2, it is possible to use a general luminescent material such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). it can. Various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range. .

Such a light source or the like is provided with a process such as a transfer process, a charge eliminating process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG. The
This neutralization mechanism can be omitted when the AC component is used in a superimposed manner in the previous charging method, or when the residual potential of the electrostatic latent image carrier is small. Further, instead of optical static elimination, an electrostatic static elimination mechanism (for example, a static elimination brush with a reverse bias applied or grounded) may be used. As described above, a document having a small writing rate has a large effect of light neutralization, and it is preferable not to use light neutralization unless there is an effect of afterimage in the next image forming cycle.
In the figure, 9 is a registration roller, 11 is a transfer bias roller, 12 is a separation claw, and 13 is a pre-cleaning charger.

  In addition, the toner developed on the electrostatic latent image carrier 1 by the developing unit 6 is transferred to the transfer paper 7, but when toner remaining on the electrostatic latent image carrier 1 is generated, the fur brush 14 And the blade 15 is removed from the electrostatic latent image carrier. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

-Tandem full-color image forming device-
FIG. 8 is a schematic diagram for explaining the tandem-type full-color image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 8, reference numerals 1C, 1M, 1Y, and 1K are drum-shaped electrostatic latent image carriers, and the electrostatic latent image carrier is at least a charge blocking layer on a conductive support. An anti-moire layer and a photosensitive layer are laminated in this order. In the photosensitive layer, the average particle diameter of primary particles is 0.25 μm or less, and an error relative to X-rays having a wavelength of 1.542 mm due to CuKα rays. The diffraction value of the Bragg angle 2θ in the range ± 0.2 ° has a maximum at 27.2 °, and at least at 7.3 °, 9.4 °, 9.6 °, and 24.0 ° It comprises a titanyl phthalocyanine crystal having a maximum value and having a maximum value greater than 7.3 and less than 9.4 ° and no maximum value at 26.3 °.

  The electrostatic latent image carriers 1C, 1M, 1Y, and 1K rotate in the direction of the arrow in the figure, and at least around them, charging members 2C, 2M, 2Y, and 2K, developing members 4C, 4M, 4Y, and 4K. Cleaning members 5C, 5M, 5Y, and 5K are disposed. The charging members 2C, 2M, 2Y, and 2K are charging members that constitute a charging device for uniformly charging the surface of the latent electrostatic image bearing member. Laser light 3C, 3M, 3Y, 3K from an exposure member (not shown) is irradiated from the surface of the electrostatic latent image carrier between the charging members 2C, 2M, 2Y, 2K and the developing members 4C, 4M, 4Y, 4K. Thus, electrostatic latent images are formed on the electrostatic latent image carriers 1C, 1M, 1Y, and 1K. Then, the four image forming elements 6C, 6M, 6Y, and 6K centering on the electrostatic latent image carriers 1C, 1M, 1Y, and 1K are juxtaposed along the transfer conveyance belt 16 that is a transfer material conveyance unit. Has been. The transfer conveyance belt 16 is provided between the developing members 4C, 4M, 4Y, and 4K of the image forming units 6C, 6M, 6Y, and 6K and the cleaning members 5C, 5M, 5Y, and 5K, and the electrostatic latent image carriers 1C, 1M, and 1Y. Transfer brushes 11 </ b> C, 11 </ b> M, 11 </ b> Y, and 11 </ b> K for applying a transfer bias are disposed on a surface (back surface) that is in contact with 1 </ b> K and contacts the back side of the transfer conveyance belt 16 on the electrostatic latent image carrier side. Each of the image forming elements 6C, 6M, 6Y, and 6K is different in the color of the toner inside the developing device, and the others are the same in configuration.

In the full-color image forming apparatus having the configuration shown in FIG. 8, the image forming operation is performed as follows. First, in each of the image forming elements 6C, 6M, 6Y, and 6K, the charging member 2C in which the electrostatic latent image carriers 1C, 1M, 1Y, and 1K rotate in the direction of the arrow (the direction along with the electrostatic latent image carrier), By 2M, 2Y, and 2K, the electrostatic latent image carrier is charged so that the electric field strength represented by the following formula is 30 V / μm or more and 60 V μm or less, preferably 30 V / μm or more and 50 V / μm or less.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)
Next, writing is performed with laser beams 3C, 3M, 3Y, and 3K in an exposure unit (not shown) arranged outside the electrostatic latent image carrier, and the electrostatic latent image corresponding to each color image to be created. Is formed. Also at this time, writing of 1200 dpi with respect to one writing light source is almost the upper limit. Next, the latent image is developed by the developing members 4C, 4M, 4Y, and 4K to form a toner image. The developing members 4C, 4M, 4Y, and 4K are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and the four electrostatic latent image carriers 1C. The toner images of each color created on 1M, 1Y, and 1K are superimposed on the transfer paper. The transfer paper 7 is sent out from the tray by a paper feed roller 17, temporarily stopped by a pair of registration rollers 9, and sent to the transfer conveyance belt 16 in synchronism with the image formation on the electrostatic latent image carrier. The transfer paper 9 held on the transfer conveyance belt 16 is conveyed, and the toner images of the respective colors are transferred at the contact positions (transfer portions) with the electrostatic latent image carriers 1C, 1M, 1Y, 1K. The toner image on the electrostatic latent image carrier is generated by an electric field formed by a potential difference between the transfer bias applied to the transfer brushes 11C, 11M, 11Y, and 11K and the electrostatic latent image carriers 1C, 1M, 1Y, and 1K. And transferred onto the transfer paper 7. Then, the transfer paper 7 on which the four color toner images are passed through the four transfer portions is conveyed to the fixing device 18 where the toner is fixed and discharged to a paper discharge portion (not shown). Further, the residual toner remaining on the electrostatic latent image carriers 1C, 1M, 1Y, and 1K without being transferred by the transfer unit is collected by the cleaning devices 5C, 5M, 5Y, and 5K. In the example of FIG. 8, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (6C, 6M, 6Y) other than black. In addition, as described above, the surface potential of the electrostatic latent image carrier after transfer is controlled to 100 V or less on the main charging polarity side, thereby reducing the increase in residual potential during repeated use of the electrostatic latent image carrier. Can be effective.

  Also in this case, it is effective that the electrostatic latent image carrier diameter is not an integral multiple of the roller diameter. In particular, a tandem type image forming apparatus has a plurality of image forming elements, and therefore may be emphasized as an image defect, which is particularly effective when outputting a color image.

  The image forming means as described above may be fixedly incorporated in a copying apparatus, facsimile, or printer, but each electrophotographic element may be incorporated in the apparatus in the form of a process cartridge. A process cartridge is a single device (part) that contains an electrostatic latent image carrier and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like.

(Process cartridge)
There are many examples of the shape and the like of the process cartridge, but a typical example is the one shown in FIG. The electrostatic latent image carrier 101 is as described above.

As the charging member 102, the electrostatic latent image carrier 101 is uniformly charged to give an electric field strength represented by the following formula of 30 V / μm to 60 V / μm, preferably 30 V / μm to 50 V / μm. Any member that can be used is not particularly limited, and a normally used charging device can be appropriately selected. As the image exposure unit 103, a light source having a beam diameter of 50 μm or less is used as described above, and the above-described electric field strength is applied to the electrostatic latent image carrier. There is no restriction | limiting in particular as the developing member 104, The normally used image development apparatus can be selected suitably. In FIG. 9, reference numeral 104 denotes a developing unit, 105 denotes a transfer body, 106 denotes a transfer unit, and 107 denotes a cleaning unit.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all. All parts are parts by weight.

<Synthesis of charge generation material (titanyl phthalocyanine crystal)>
First, a synthesis example of a charge generation material (titanyl phthalocyanine crystal) will be described.
(Comparative Synthesis Example 1)
A pigment was prepared according to Japanese Patent Application Laid-Open No. 2001-19871. That is, 29.2 parts of 1,3-diiminoisoindoline and 200 parts of sulfolane are mixed, and 20.4 parts of titanium tetrabutoxide are added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After the completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained. Crude titanyl phthalocyanine is dissolved in 20 times the amount of concentrated sulfuric acid, added dropwise to 100 times the amount of ice water with stirring, the precipitated crystals are filtered, and then ion-exchanged water (pH: 7.0, until the washing solution becomes neutral). Repeated washing with specific conductivity (1.0 μS / cm) (pH value of ion-exchanged water after washing was 6.8, specific conductivity was 2.6 μS / cm), wet cake of titanyl phthalocyanine pigment ( Water paste) was obtained. 40 parts of this wet cake (water paste) obtained was put into 200 parts of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder (referred to as pigment 1).
The solid content concentration of the wet cake was 15% by mass. The weight ratio of the crystallization solvent to the wet cake is 33 times. In addition, the raw material of the comparative synthesis example 1 does not use a halide.
The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a result, the Bragg angle 2θ with respect to Cu-Kα characteristic X-ray (wavelength 1.542 mm) was 27.2 ± 0.2 °, and the maximum peak and the minimum Titanyl with a peak at an angle of 7.3 ± 0.2 ° and no peak between the peak at 7.3 ° and the peak at 9.4 ° and no peak at 26.3 ° A phthalocyanine powder was obtained. The result is shown in FIG.

-X-ray diffraction spectrum measurement conditions-
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

  A part of the water paste obtained in Comparative Synthesis Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain a low crystalline titanyl phthalocyanine powder. The X-ray diffraction spectrum of the dry powder of water paste is shown in FIG.

(Comparative Synthesis Example 2)
A pigment was prepared according to the method described in Example 1 of JP-A-1-299874. That is, the wet cake produced in the previous Comparative Synthesis Example 1 was dried, 1 part of the dried product was added to 50 parts of polyethylene glycol, and sand milling was performed with 100 parts of glass beads. After the crystal transition, the resultant was washed successively with dilute sulfuric acid and an aqueous ammonium hydroxide solution and dried to obtain a pigment (referred to as pigment 2). The raw material of Comparative Synthesis Example 2 does not use a halide.

(Comparative Synthesis Example 3)
A pigment was produced according to the method described in Production Example 1 of JP-A-3-269064. That is, the wet cake prepared in the previous Comparative Synthesis Example 1 was dried, and 1 part of the dried product was stirred in a mixed solvent of 10 parts of ion-exchanged water and 1 part of monochlorobenzene for 1 hour (50 ° C.), and then methanol and ions It was washed with exchanged water and dried to obtain a pigment (referred to as pigment 3). The raw material of Comparative Synthesis Example 3 does not use a halide.

(Comparative Synthesis Example 4)
A pigment was produced according to the method described in the production example of JP-A-2-8256. That is, 9.8 parts of phthalodinitrile and 75 parts of 1-chloronaphthalene are stirred and mixed, and 2.2 parts of titanium tetrachloride are added dropwise under a nitrogen stream. After completion of the dropping, the temperature was gradually raised to 200 ° C., and the reaction was carried out by stirring for 3 hours while maintaining the reaction temperature between 200 ° C. and 220 ° C. After completion of the reaction, the mixture was allowed to cool to 130 ° C. and filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further with hot water at 80 ° C. After washing twice, it was dried to obtain a pigment (referred to as pigment 4). As a raw material of Comparative Synthesis Example 4, a halide is used.

(Comparative Synthesis Example 5)
A pigment was prepared according to the method described in Synthesis Example 1 of JP-A No. 64-17066. That is, 5 parts of α-type TiOPc was crystallized at 100 ° C. for 10 hours with a sand grinder together with 10 parts of sodium chloride and 5 parts of acetophenone. This was washed with ion-exchanged water and methanol, purified with dilute sulfuric acid aqueous solution, washed with ion-exchanged water until the acid content disappeared, and dried to obtain a pigment (referred to as pigment 5). The raw material of Comparative Synthesis Example 5 uses a halide.

(Comparative Synthesis Example 6)
A pigment was prepared according to the method described in Example 1 of JP-A-11-5919. That is, 20.4 parts of O-phthalodinitrile and 7.6 parts of titanium tetrachloride were heated and reacted in 50 parts of quinoline at 200 ° C. for 2 hours, and then the solvent was removed by steam distillation. Purified with an aqueous sodium hydroxide solution, washed with methanol and N, N-dimethylformamide and dried to obtain titanyl phthalocyanine. 2 parts of this titanyl phthalocyanine is dissolved little by little in 40 parts of 98% sulfuric acid at 5 ° C., and the mixture is stirred for about 1 hour while maintaining the temperature at 5 ° C. or less. Subsequently, the sulfuric acid solution is slowly poured into 400 parts of ice water stirred at a high speed, and the precipitated crystals are filtered. The crystals are washed with distilled water until no acid remains, and a wet cake is obtained. The cake was stirred in 100 parts of THF for about 5 hours, filtered, washed with THF and dried to obtain a pigment (referred to as pigment 6). As a raw material of Comparative Synthesis Example 6, a halide is used.

(Comparative Synthesis Example 7)
A pigment was prepared according to the method described in Synthesis Example 2 of JP-A-3-255456. That is, 10 parts of the wet cake prepared in the previous Comparative Synthesis Example 1 was mixed with 15 parts of sodium chloride and 7 parts of diethylene glycol, and milled for 60 hours with an automatic mortar under heating at 80 ° C. Next, sufficient water washing was performed to completely remove sodium chloride and diethylene glycol contained in the treated product. After drying this under reduced pressure, 200 parts of cyclohexanone and glass beads having a diameter of 1 mm were added, and the mixture was treated with a sand mill for 30 minutes to obtain a pigment (referred to as pigment 7). The raw material of Comparative Synthesis Example 7 does not use a halide.

(Comparative Synthesis Example 8)
A pigment was prepared according to the method for producing a titanyl phthalocyanine crystal of JP-A-8-110649. Specifically, 58 parts of 1,3-diiminoisoindoline and 51 parts of tetrabutoxytitanium were reacted in 210 parts of α-chloronaphthalene at 210 ° C. for 5 hours, followed by α-chloronaphthalene and dimethylformamide (DMF) in this order. Washed. Thereafter, it was washed with hot DMF, hot water and methanol and dried to obtain 50 parts of titanyl phthalocyanine. 4 parts of titanyl phthalocyanine was added to 400 parts of sulfuric acid cooled to 0 ° C., followed by stirring at 0 ° C. for 1 hour. After confirming that phthalocyanine was completely dissolved, it was added to a 800 mL water / 800 mL toluene mixture cooled to 0 ° C. After stirring at room temperature for 2 hours, the precipitated phthalocyanine mixed crystal was filtered from the mixed solution and washed with methanol and water in this order. After confirming the neutrality of the washing water, the phthalocyanine mixed crystal was filtered from the washing water and dried to obtain 2.9 parts of titanyl phthalocyanine mixed crystal. The raw material of Comparative Synthesis Example 8 does not use a halide.

(Synthesis Example 1)
According to the method of Comparative Synthesis Example 1, a water paste of titanyl phthalocyanine pigment was synthesized and crystallized as follows to obtain phthalocyanine crystals having smaller primary particles than Comparative Synthesis Example 1.
To 60 parts of the pre-crystallization water paste obtained in Comparative Synthesis Example 1, 400 parts of tetrahydrofuran was added and stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. When the color changed to light blue (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filter were washed with tetrahydrofuran to obtain a pigment wet cake. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts of titanyl phthalocyanine crystals (referred to as pigment 9). The raw material of Synthesis Example 1 does not use a halide. The solid content concentration of the wet cake was 15 wt%. The weight ratio of crystallization solvent to wet cake is 44 times.

(Synthesis Example 2)
In Synthesis Example 1, except that the stirring time was changed to 30 minutes, crystallization was performed in the same manner as in Synthesis Example 1 to obtain a titanyl phthalocyanine crystal (referred to as pigment 10).

(Synthesis Example 3)
In Synthesis Example 1, except that the stirring time was changed to 40 minutes, crystallization was performed in the same manner as in Synthesis Example 1 to obtain a titanyl phthalocyanine crystal (referred to as Pigment 11).

  A portion of the pre-crystallized titanyl phthalocyanine (water paste) prepared in Comparative Synthesis Example 1 was diluted with ion-exchanged water to approximately 1% by mass, and the surface was scooped with a copper net having been subjected to conductive treatment. The particle size of phthalocyanine was observed with a transmission electron microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75000 times. The volume average particle diameter was determined as follows.

The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. The arithmetic average of the major axis of the measured 30 individuals was determined and used as the volume average particle size.
The volume average particle diameter in the water paste in Synthesis Example 1 determined by the above method was 0.06 μm.

  Further, the titanyl phthalocyanine crystal after crystal conversion just before filtration in Comparative Synthesis Example 1 and Synthesis Examples 1 to 3 was diluted with tetrahydrofuran so as to be about 1% by mass, and observed in the same manner as the above method. Table 1 shows the volume average particle diameter determined as described above. In addition, the titanyl phthalocyanine crystal produced in Comparative Synthesis Example 1 and Synthesis Examples 1 to 3 did not necessarily have the same shape of all crystals (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was performed with the length of the largest diagonal line of the crystal as the major axis.

  The pigments 2 to 8 prepared in the above Comparative Synthesis Examples 2 to 8 were measured for X-ray diffraction spectra by the same method as described above, and were confirmed to be the same as the spectra described in the respective publications. Further, the X-ray diffraction spectra of the pigments 9 to 11 prepared in Synthesis Examples 1 to 3 coincided with the spectrum of the pigment 1 prepared in Comparative Synthesis Example 1. Table 2 shows the characteristics of each X-ray diffraction spectrum and the peak position of the X-ray diffraction spectrum of the pigment obtained in Comparative Synthesis Example 1.

<Synthesis of a compound having a monofunctional charge transporting structure>
Next, a synthesis example of a compound having a monofunctional charge transporting structure used for a protective layer of an example of preparing an electrostatic latent image carrier described later will be described.

(Synthesis example of a compound having a monofunctional charge transporting structure)
The compound having a monofunctional charge transport structure in the present invention is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example of this is shown below.

(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 parts (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 parts of sodium iodide (0. 92 mol) was added 240 parts of sulfolane and heated to 60 ° C. in a nitrogen stream. 99 parts (0.91 mol) of trimethylchlorosilane was dropped into this liquid over 1 hour, and the reaction was terminated by stirring for 4 hours and a half at a temperature of about 60 ° C.
About 1500 parts of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous sodium carbonate solution.
Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1).
Cyclohexane was added to the obtained pale yellow oil to precipitate crystals.
In this way, 88.1 parts (yield = 80.4%) of white crystals of the following structural formula B were obtained.
Melting point: 64.0-66.0 ° C
Elemental analysis values are shown in Table 3.

(2) Synthesis example of triarylamino group-substituted acrylate compound (Exemplary Compound No. 54)
82.9 parts (0.227 mol) of the hydroxy group-substituted triarylamine compound (Structural Formula B) obtained in (1) above is dissolved in 400 parts of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.2. 4 parts, water: 100 parts) was added dropwise.
This solution was cooled to 5 ° C., and 25.2 parts (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was complete | finished.
The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals.
In this way, Exemplified Compound No. 54.73 parts of white crystals (yield = 84.8%) were obtained.
Melting point: 117.5-119.0 ° C
The elemental analysis values are shown in Table 4.

<Preparation of dispersion (charge generation coating solution)>
Next, dispersion is performed using the titanyl phthalocyanine crystal obtained by the above-described synthesis method, and the resulting dispersion (coating liquid for charge generation layer) is described.

(Dispersion Preparation Example 1)
Pigment 1 prepared in Comparative Synthesis Example 1 was dispersed under the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.
Titanyl phthalocyanine pigment (Pigment 1) 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts A commercially available bead mill disperser was used to dissolve polyvinyl butyral using PSZ balls having a diameter of 0.5 mm. All butanone and pigment were added, and the rotor rotation speed was 1200 r. p. m. Was dispersed for 30 minutes to prepare a dispersion (referred to as Dispersion 1).

(Dispersion Preparation Examples 2 to 11)
In place of Pigment 1 used in Dispersion Preparation Example 1, pigments 2 to 11 prepared in Comparative Synthesis Examples 2 to 8 and Synthesis Examples 1 to 3 were used, respectively, and dispersed under the same conditions as Dispersion Preparation Example 1. Liquids were produced (corresponding to the pigment numbers, dispersions 2 to 11, respectively).

(Dispersion Preparation Example 12)
The dispersion 1 prepared in Dispersion Preparation Example 1 was filtered using a cotton wind cartridge filter, TCW-1-CS (pore diameter 1 μm) manufactured by Advantech. In filtration, a pump was used to perform filtration in a pressurized state to obtain a filtrate (referred to as dispersion 12).

(Dispersion Preparation Example 13)
Dispersion liquid was subjected to pressure filtration in the same manner as in Dispersion Preparation Example 10, except that the filter used in Dispersion Preparation Example 10 was changed to Advantech Co., Ltd., Cotton Wind Cartridge Filter, TCW-3-CS (pore diameter 3 μm). Was made (dispersion 13).

(Dispersion Preparation Example 14)
Dispersion liquid was subjected to pressure filtration in the same manner as in Dispersion Preparation Example 12 except that the filter used in Dispersion Preparation Example 12 was changed to an Advantech Co., Ltd., cotton wind cartridge filter, TCW-5-CS (pore size 5 μm). Was made (dispersion liquid 14).

(Dispersion Preparation Example 15)
Dispersion was performed by changing the dispersion conditions in Dispersion Preparation Example 1 as follows (referred to as Dispersion 15). Rotor rotation speed: 1000 r. p. m. For 20 minutes.

(Dispersion Preparation Example 16)
The dispersion prepared in Dispersion Preparation Example 15 was filtered using a cotton wind cartridge filter, TCW-1-CS (pore diameter 1 μm) manufactured by Advantech. During filtration, a pump was used and filtration was performed in a pressurized state. During the filtration, the filter was clogged, and all of the dispersion liquid could not be filtered. For this reason, the following measurement was not implemented.

The particle size distribution of the pigment particles in the dispersion prepared as described above was measured with Horiba: CAPA-700. The results are shown in Table 5.

<Preparation of electrostatic latent image carrier>
Next, a method for producing an electrostatic latent image carrier produced using the dispersion liquid obtained by the above-described method will be described.

(Electrostatic latent image carrier production example 1)
A 100 mm diameter aluminum cylinder (JIS 1050) was coated with a charge blocking layer coating liquid, a moire prevention layer coating liquid, a charge generation layer coating liquid, and a charge transport layer coating liquid having the following composition in sequence and dried. A laminated electrostatic latent image carrier was prepared by forming a 0.0 μm charge blocking layer, a 3.5 μm moiré preventing layer, a charge generation layer, and a 28 μm charge transport layer (referred to as electrostatic latent image carrier 1).
The film thickness of the charge generation layer was adjusted so that the transmittance of the charge generation layer at 780 nm was 25%. The charge generation layer has a transmittance as follows. A charge generation layer coating solution having the following composition is applied to an aluminum cylinder wrapped with a polyethylene terephthalate film under the same conditions as the production of the electrostatic latent image carrier, and the charge generation layer is applied. The transmittance | permeability of 780 nm was evaluated with the commercially available spectrophotometer (Shimadzu: UV-3100) by making the polyethylene terephthalate film which has not been made into a comparison control.

[Charge blocking layer coating solution]
N-methoxymethylated nylon (Lead City: Fine Resin FR-101) 4 parts Methanol 70 parts n-Butanol 30 parts

[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

[Charge generation layer coating solution]
The previously prepared dispersion 1 was used.

[Charge transport layer coating solution]
Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material having the following structural formula 7 parts Tetrahydrofuran 80 parts

(Electrostatic latent image carrier production examples 2 to 15)
As in the electrostatic latent image carrier production example 1, the charge generation layer coating liquid (dispersion liquid 1) used in the electrostatic latent image carrier production example 1 was changed to dispersions 2 to 15, respectively. An electrostatic latent image carrier was prepared. The film thickness of the charge generation layer was adjusted so that the transmittance at 780 nm was 25% when all the coating liquids were used, as in the electrostatic latent image carrier production example 1 (dispersion number). Corresponding to the electrostatic latent image carriers 2 to 15).

(Electrostatic latent image carrier preparation example 16)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the charge blocking layer was not provided in electrostatic latent image carrier production example 9 (electrostatic latent image carrier 16 and To do).

(Electrostatic latent image carrier preparation example 17)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the moire prevention layer was not provided in electrostatic latent image carrier production example 9 (electrostatic latent image carrier 17 and To do).

(Electrostatic latent image carrier production example 18)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9 except that the coating order of the charge blocking layer and the moire prevention layer was changed in the electrostatic latent image carrier production example 9 ( Electrostatic latent image carrier 18).

(Electrostatic latent image carrier production example 19)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the thickness of the charge blocking layer was 0.2 μm in electrostatic latent image carrier production example 9 (electrostatic latent image carrier production example 9). The latent image carrier 19).

(Electrostatic latent image carrier preparation example 20)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the thickness of the charge blocking layer was changed to 0.5 μm in electrostatic latent image carrier production example 9 (electrostatic latent image carrier production example 9). The latent image carrier 20).

(Electrostatic latent image carrier production example 21)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the thickness of the charge blocking layer was 0.8 μm in electrostatic latent image carrier production example 9 (electrostatic latent image carrier production example 9). A latent image carrier 21).

(Electrostatic latent image carrier preparation example 22)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the thickness of the charge blocking layer was 1.8 μm in electrostatic latent image carrier production example 9 (electrostatic latent image carrier production example 9). A latent image carrier 22).

(Electrostatic latent image carrier preparation example 23)
An electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 9 except that the thickness of the charge blocking layer was set to 2.2 μm in electrostatic latent image carrier production example 9. A latent image carrier 23).

(Electrostatic latent image carrier production example 24)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9 except that the charge blocking layer coating solution was changed to one having the following composition in the electrostatic latent image carrier production example 9 ( The electrostatic latent image carrier 24).
[Charge blocking layer coating solution]
Alcohol-soluble nylon (Toray: Amilan CM8000) 4 parts Methanol 70 parts n-Butanol 30 parts

(Electrostatic latent image carrier preparation example 25)
In the electrostatic latent image carrier production example 9, the charge blocking layer coating solution was changed to the following composition, and the film thickness was changed to 0.6 μm, similarly to the electrostatic latent image carrier production example 9. An electrostatic latent image carrier was produced (referred to as an electrostatic latent image carrier 25).
[Charge blocking layer coating solution]
Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 400 parts

(Electrostatic latent image carrier production example 26)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 26).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 168 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 180 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 2/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier production example 27)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 27).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 250 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 280 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier production example 28)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 28).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 90 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 90 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier preparation example 29)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( It is referred to as an electrostatic latent image carrier 29).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 76 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 80 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 0.9 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier preparation example 30)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 30).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 280 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 300 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3.3 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier preparation example 31)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 31).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts N-methoxymethylated nylon (Lead City: Fine Resin FR-101) 27.5 parts Tartaric acid (curing catalyst) 1 part 2 -Butanone 100 parts In the said composition, the volume ratio of an inorganic pigment and binder resin is 1.5 / 1.

(Electrostatic latent image carrier production example 32)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 32).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink and Chemicals Co., Ltd.] 22.4 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 28 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 4/6 weight ratio.

(Electrostatic latent image carrier preparation example 33)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 33).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 28 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 23.3 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment and the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 5/5 weight ratio.

(Electrostatic latent image carrier production example 34)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 34).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 39.2 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 14 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 7/3 weight ratio.

(Electrostatic latent image carrier production example 35)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( It is referred to as an electrostatic latent image carrier 35).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 44.8 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 9.3 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 8/2 weight ratio.

(Electrostatic latent image carrier production example 36)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 36).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 50.4 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 4.7 parts 2-butanone 130 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is 9/1 weight ratio.

(Electrostatic latent image carrier preparation example 37)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 37).
[Moire prevention layer coating solution]
Zinc oxide (SAZEX 4000: manufactured by Sakai Chemical) 110 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 120 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.3 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Electrostatic latent image carrier production example 38)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 38).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (PT-401M: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm) 63 parts Alkyd resin [Beckolite M6401 -50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of average particle diameter is 0.28, and the mixing ratio of both is 0.5.

(Electrostatic latent image carrier production example 39)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 39).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 113.4 parts Titanium oxide (PT-401M: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm) 12.6 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The average particle size ratio is 0.28, and the mixing ratio of both is 0.1.

(Electrostatic latent image carrier preparation example 40)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 40).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 12.6 parts Titanium oxide (PT-401M: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.07 μm)
113.4 parts alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter is 0.28, and the mixing ratio of both is 0.9.

(Electrostatic latent image carrier production example 41)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( Electrostatic latent image carrier 41).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (TTO-F1: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.04 μm) 63 parts Alkyd resin [Beckolite M6401 -50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter is 0.16, and the mixing ratio of both is 0.5.

(Electrostatic latent image carrier production example 42)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9, except that in the electrostatic latent image carrier production example 9, the moiré prevention layer coating solution was changed to one having the following composition ( The electrostatic latent image carrier 42).
[Moire prevention layer coating solution]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 63 parts Titanium oxide (A-100: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.15 μm) 63 parts Alkyd resin [Beckolite M6401 -50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 140 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.
The ratio of the average particle diameter is 0.6, and the mixing ratio of both is 0.5.

(Electrostatic latent image carrier production example 43)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 9 except that the charge transport layer coating liquid in the electrostatic latent image carrier production example 9 was changed to the following composition ( The electrostatic latent image carrier 43).
[Charge transport layer coating solution]
Polymer charge transport material of the following structural formula (α) (weight average molecular weight: about 135000)
10 parts Additive of the following structural formula (β) 0.5 part Methylene chloride 100 parts

(Electrostatic latent image carrier production example 44)
In the electrostatic latent image carrier preparation example 9, the thickness of the charge transport layer was 23 μm, and a protective layer coating solution having the following composition was applied and dried on the charge transport layer, and a 5 μm protective layer was provided. An electrostatic latent image carrier was produced in the same manner as in Image carrier production example 9 (referred to as electrostatic latent image carrier 44).
[Protective layer coating solution]
Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd., viscosity average molecular weight: 50,000)
10 parts Charge transport material having the following structural formula 7 parts Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
4 parts Cyclohexanone 500 parts Tetrahydrofuran 150 parts

(Electrostatic latent image carrier production example 45)
The alumina fine particles in the protective layer coating solution in the electrostatic latent image carrier preparation example 44 were changed to 4 parts of titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm, average primary particle size: 0.5 μm). Except for the above, an electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 44 (referred to as an electrostatic latent image carrier 45).

(Electrostatic latent image carrier preparation example 46)
The alumina fine particles in the protective layer coating solution in the electrostatic latent image carrier preparation example 44 were changed to 4 parts of tin oxide-antimony oxide powder (resistivity: 10 ⁶ Ω · cm, average primary particle size 0.4 μm). Except for the above, an electrostatic latent image carrier was produced in the same manner as in electrostatic latent image carrier production example 44 (referred to as electrostatic latent image carrier 46).

(Electrostatic latent image carrier preparation example 47)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 44 except that the protective layer coating solution in the electrostatic latent image carrier production example 44 was changed to the following. A latent image carrier 47).
[Protective layer coating solution]
Polymer charge transport material having the following structural formula (weight average molecular weight: about 135000) 10 parts Alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
4 parts Cyclohexanone 500 parts Tetrahydrofuran 150 parts

(Electrostatic latent image carrier preparation example 48)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 44 except that the protective layer coating solution in the electrostatic latent image carrier production example 44 was changed to the following. A latent image carrier 48).
[Protective layer coating solution]
Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transport compound of the following structural formula 35 parts Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) 1 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Electrostatic latent image carrier preparation example 49)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 44 except that the protective layer coating solution in the electrostatic latent image carrier production example 44 was changed to the following. A latent image carrier 49).
[Protective layer coating solution]
Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transport compound of the following structural formula 35 parts α-alumina particles (Sumicorundum AA-03: manufactured by Sumitomo Chemical Co., Ltd.) 15 parts Antioxidant (Sanol LS2626: Sankyo Chemical Co., Ltd.) ) 1 part Polycarboxylic acid compound BYK P104: BYK Chemie 0.4 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts

(Electrostatic latent image carrier preparation example 50)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 44 except that the protective layer coating solution in the electrostatic latent image carrier production example 44 was changed to the following. A latent image carrier 50).
The protective layer is naturally dried for 20 minutes after spray coating, and then the coating film is cured by light irradiation under conditions of a metal halide lamp: 160 W / cm, irradiation intensity: 500 mW / cm ² , irradiation time: 60 seconds. I let you.
[Protective layer coating solution]
Trifunctional or higher radical polymerizable monomer having no charge transport structure 10 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
Exemplary compounds as radically polymerizable compounds having a monofunctional charge transport structure
10 parts Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Electrostatic latent image carrier production example 51)
An electrostatic latent image carrier was produced in the same manner as in the electrostatic latent image carrier production example 50 except that the charge transport layer coating solution in the electrostatic latent image carrier production example 50 was changed to the following composition ( The electrostatic latent image carrier 51).
[Charge transport layer coating solution]
Polymer charge transport material having the following composition (weight average molecular weight: about 135000) 10 parts Methylene chloride 100 parts

(Electrostatic latent image carrier preparation example 52)
In Example 50 for preparing an electrostatic latent image carrier, all except that the radical polymerizable monomer having a trifunctional or higher functionality having no charge transporting structure contained in the protective layer coating solution was changed to the following radical polymerizable monomer An electrostatic latent image carrier 52 was produced in the same manner as in Example 50 for preparing an electrostatic latent image carrier.
10 parts of tri- or higher functional radical polymerizable monomer having no charge transport structure (pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
(Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88)

(Electrostatic latent image carrier preparation example 53)
The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the protective layer coating liquid of the electrostatic latent image bearing member preparation example 50 is converted into a bifunctional having no following charge transporting structure. An electrostatic latent image carrier 53 was produced in the same manner as in Example 1 except that the radical polymerizable monomer was changed to 10 parts.
10 parts of a bifunctional radically polymerizable monomer having no charge transporting structure (1,6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries, Ltd.))
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113)

(Electrostatic latent image carrier production example 54)
In the electrostatic latent image carrier preparation example 50, the tri- or higher functional radical polymerizable monomer having no charge transport structure contained in the coating liquid for a crosslinkable charge transport layer is replaced with the following radical polymerizable monomer. An electrostatic latent image carrier 54 was produced in the same manner as in the electrostatic latent image carrier production example 50 except that the photopolymerization initiator was changed to 1 part of the following compound.
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 10 parts (Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku)
(Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325)

(Electrostatic latent image carrier preparation example 55)
A radical polymerizable compound having a monofunctional charge transporting structure contained in the protective layer coating solution of Preparation Example 50 for electrostatic latent image carrier is a radical having a bifunctional charge transporting structure represented by the following structural formula. An electrostatic latent image carrier 55 was produced in the same manner as in the electrostatic latent image carrier production example 50 except that the polymerizable compound was replaced with 10 parts.

(Electrostatic latent image carrier preparation example 56)
An electrostatic latent image carrier 56 was produced in the same manner as in the electrostatic latent image carrier preparation example 50 except that the protective layer coating solution was changed to the following composition in the electrostatic latent image carrier preparation example 50.
[Protective layer coating solution]
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 6 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
Exemplified compound No. 1 as a radical polymerizable compound having a monofunctional charge transporting structure. 54 14 parts Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Electrostatic latent image carrier preparation example 57)
An electrostatic latent image carrier 57 was produced in the same manner as in the electrostatic latent image carrier preparation example 50 except that the protective layer coating solution was changed to the following composition in the electrostatic latent image carrier preparation example 50.
[Protective layer coating solution]
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 14 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
Exemplified compound No. 1 as a radical polymerizable compound having a monofunctional charge transporting structure. 54 6 parts Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Electrostatic latent image carrier production example 58)
An electrostatic latent image carrier 58 was produced in the same manner as in the electrostatic latent image carrier preparation example 50 except that the protective layer coating solution was changed to the following composition in the electrostatic latent image carrier preparation example 50.
[Protective layer coating solution]
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 2 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
Exemplified compound No. 1 as a radical polymerizable compound having a monofunctional charge transporting structure. 54 18 parts Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Electrostatic latent image carrier preparation example 59)
An electrostatic latent image carrier 59 was produced in the same manner as in the electrostatic latent image carrier preparation example 50 except that the protective layer coating solution was changed to the following composition in the electrostatic latent image carrier preparation example 50.
[Protective layer coating solution]
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 18 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
Exemplified compound No. 1 as a radical polymerizable compound having a monofunctional charge transporting structure. 54 2 parts Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

(Electrostatic latent image carrier preparation example 60)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 1 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 1 (referred to as electrostatic latent image carrier 60).

(Electrostatic latent image carrier production example 61)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 4 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 4 (referred to as electrostatic latent image carrier 61).

(Electrostatic latent image carrier production example 62)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 6 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 6 (referred to as electrostatic latent image carrier 62).

(Electrostatic latent image carrier production example 63)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 9 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 9 (referred to as electrostatic latent image carrier 63).

(Electrostatic latent image carrier production example 64)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 11 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 11 (referred to as an electrostatic latent image carrier 64).

(Electrostatic latent image carrier production example 65)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier preparation example 12 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 12 (referred to as an electrostatic latent image carrier 65).

(Electrostatic latent image carrier production example 66)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier preparation example 16 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 16 (referred to as electrostatic latent image carrier 66).

(Electrostatic latent image carrier production example 67)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier preparation example 17 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 17 (referred to as an electrostatic latent image carrier 67).

(Electrostatic latent image carrier production example 68)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 18 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 18 (referred to as electrostatic latent image carrier 68).

(Electrostatic latent image carrier production example 69)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 38 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 25 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 38 (referred to as an electrostatic latent image carrier 69).

(Electrostatic latent image carrier preparation example 70)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier production example 44 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 20 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 44 (referred to as electrostatic latent image carrier 70).

(Electrostatic latent image carrier production example 71)
The electrostatic latent image carrier except that the conductive support used in the electrostatic latent image carrier preparation example 50 was changed to an aluminum cylinder (JIS1050) having a diameter of 40 mm and the thickness of the charge transport layer was changed to 20 μm. An electrostatic latent image carrier was produced in the same manner as in Production Example 50 (referred to as electrostatic latent image carrier 71).

The external appearance of the electrostatic latent image carriers 50 to 59 produced as described above was visually observed to determine the presence or absence of cracks and film peeling. Next, as a solubility test for an organic solvent, one drop of tetrahydrofuran (hereinafter abbreviated as THF) and dichloromethane were dropped, and the change in the surface shape after natural drying was observed. The results are shown in Table 6.

<Evaluation of electrostatic latent image carrier>
(Example 1 5,7～9, and 13-29, Reference Example 6, and 10-12 and Comparative Example 1-22)
The electrostatic latent image carriers 1 to 42 produced as described above were mounted on the image forming apparatus process cartridge shown in FIG. 9 and mounted on the image forming apparatus shown in FIG. The charging member is a scorotron charging member, charged under the following charging conditions, the image exposure light source is a semiconductor laser having an oscillation wavelength of 655 nm, a coupling lens, an aperture, a cylindrical lens, a polygon mirror, a scanning A beam having a major axis of 45 μm was formed by an image exposure apparatus comprising a lens, and writing was performed on the electrostatic latent image carrier. A transfer belt was used as the transfer member, and a 780 nm LED was used as the charge removal light. After the entire surface of the electrostatic latent image carrier was irradiated with light, the charge was removed. Under these conditions, 300,000 sheets were continuously printed using a chart with a writing rate of 6% (the test environment is 22 ° C.-55% RH).
The charging conditions were the following two conditions.
Charging condition 1:
Discharge voltage: -6.0 kV
Grid voltage: -920V (surface potential of unexposed portion of electrostatic latent image carrier is -900V)
Development bias: -650V
Charging condition 2:
Discharge voltage: -5.8 kV
Grid voltage: -780V (surface potential of unexposed portion of electrostatic latent image carrier is -750V)
Development bias: -500V

After printing 300,000 sheets, the following items were evaluated. In the image evaluation, the image was output with the charging conditions set so as to be the same as the initial electric field strength.
(I) Evaluation of background stain: A white solid image was output, and rank evaluation was performed based on the number and size of black spots generated on the background portion. (Ii) Evaluation of dot formation state:
A halftone image (one dot image having a diameter of 50 μm) was formed, and the dot formation state was evaluated from the observation results (dot scattering state and dot reproducibility).
(Iii) Evaluation of dot outline:
The sharpness of the periphery (edge) portion of the dots was observed, and rank evaluation was performed.
(Iv) Others: Evaluation of image density evaluation, moire evaluation, etc. (only described when a defect occurs)
Image density evaluation: A black solid image was output, and the image density of the solid part was evaluated.
Moire evaluation: A halftone image was output and the presence or absence of moire was evaluated.
The rank evaluation was performed in four stages. Very good ones were indicated by 、, good ones were indicated by ○, slightly inferior ones were indicated by Δ, and very bad ones were indicated by ×.

(Comparative Examples 23-73)
Example 1 5,7～9, and 13-29, Reference Example 6, and 10-12 and Comparative Examples 1 to 22, and change only the image exposure light source to those having a beam diameter of diameter 60 [mu] m, other In an image forming apparatus under exactly the same conditions, 300,000 sheets were continuously printed in the same manner, and the image quality was compared.

These results are shown in Tables 7-9. In the table, the electric field strength was obtained by the following formula.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)

(Examples 30 to 35 and Comparative Examples 74 and 75)
Using the electrostatic latent image carrier 9 produced in the above-mentioned electrostatic latent image carrier production example 9, the same image forming apparatus as in Example 1 was used, and the charging conditions were changed and applied to the electrostatic latent image carrier. In the state where the electric field strength to be changed was changed as shown in Table 10, changes in the initial background contamination, dot formation, and dot outline state were confirmed.

(Example 36)
In Example 1, the chart used for the paper passing test was changed to a chart with a writing rate of 1%, and continuous printing of 300,000 sheets was performed. At this time, in order to measure the electrostatic latent image carrier surface potential at the development site of the image forming apparatus shown in FIG. 7 and the electrostatic latent image carrier surface potential immediately after transfer, the surface potential meter is modified so that it can be set. went.
Before and after the paper passing test, the potential of the exposed portion of the electrostatic latent image carrier at the development site was measured. At this time, in order to measure the surface potential of the exposed portion, the optical writing was performed on the entire surface of the electrostatic latent image carrier.
In the paper passing test in Example 36, the transfer bias was adjusted so that the potential of the electrostatic latent image carrier non-writing portion after transfer was −150V. In this measurement, optical writing was performed, and the potential after transfer of the electrostatic latent image carrier was measured. The results are shown in Table 11.

(Example 37)
The test was conducted in the same manner as in Example 36 except that the potential of the electrostatic latent image carrier non-writing portion after transfer was adjusted to −80 V in Example 36. The results are shown in Table 11.

(Example 38)
The test was performed in the same manner as in Example 36 except that the potential of the electrostatic latent image carrier non-writing portion after transfer was adjusted to −80 V in Example 36. The results are shown in Table 11.

(Examples 39 to 56 and Comparative Examples 76 to 93)
The electrostatic latent image carrier obtained by the above-described electrostatic latent image carrier production examples 9 and 43 to 59 is mounted on a process cartridge for an image forming apparatus as shown in FIG. 9 to form an image as shown in FIG. Installed in the device. The charging member is a scorotron charging member, the image exposure light source is a 780 nm semiconductor laser (image writing using a polygon mirror with a beam diameter of 45 μm), the transfer member is a transfer belt, and the following charging conditions are used. Then, continuous printing of 500,000 sheets was performed using a chart with a writing rate of 6% (the test environment is 22 ° C.-55% RH).
The following conditions were used for charging conditions.
Charging condition 1:
Applied voltage to the wire: -6.0 KV
Grid voltage: -920 V (the potential of the unexposed portion of the electrostatic latent image carrier is -900 V)
Charging condition 2:
Applied voltage to the wire: -5.8KV
Grid voltage: -780V (the potential of the unexposed portion of the electrostatic latent image carrier is -750V)
The image evaluation was performed after printing 500,000 sheets. At the time of image evaluation, the image was output with the charging conditions set so as to be the same as the initial electric field strength.
(I) Evaluation of background stain: A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state: A halftone image (one dot image having a diameter of 50 μm) was formed, and rank evaluation was performed on the dot formation state based on the observation results (dot scattering state and dot reproducibility).
(Iii) Evaluation of dot contour: The sharpness of the periphery (edge) portion of the dot was observed, and rank evaluation was performed.
(Iv) Others: Evaluation of image density, moire evaluation (only described when trouble occurs)
The rank evaluation was performed in four stages. Very good ones were indicated by 、, good ones by 、, slightly inferior ones by Δ, and very bad ones by x.
Further, the film thickness of the electrostatic latent image bearing member was measured at the initial stage and after printing 500,000 sheets, and the wear amount of the photosensitive layer or the protective layer in printing 500,000 sheets was evaluated. The results are shown in Table 12.

(Examples 57 to 72)
The electrostatic latent image carriers 44 to 59 provided with the protective layer prepared as described above were subjected to the above-mentioned 500,000 sheet passing test (Examples 43 to 60), and then the high temperature and high humidity environment (30 ° C. − At 90% RH), an additional 500 sheets were tested and image evaluation was performed. Evaluation conditions were in accordance with Examples 39-56. As charging conditions, charging condition 1 was used.
The following three evaluations were carried out after printing 500 sheets. At the time of image evaluation, the image was output with the charging conditions set so as to be the same as the initial electric field strength.
(I) Evaluation of background stain: A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Ii) Evaluation of image density: A black solid image was output, and the solid image density was evaluated. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
(Iii) A one-dot image was output, and the clarity of the dot outline was ranked. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.
The results are shown in Table 13.

(Examples 73-78 and Comparative Examples 94-111)
The electrostatic latent image carriers of Production Examples 60 to 71 produced as described above are mounted on a process cartridge for an image forming apparatus as shown in FIG. 9 together with a charging member. The tandem full-color image forming apparatus shown in FIG. In the four image forming elements, a contact charging type charging roller is used as a charging member, and a 780 nm semiconductor laser is used as an image exposure light source, which is arranged in an array on a glass substrate (electrostatic latent image carrier longitudinal direction). Then, writing was performed on the surface of the electrostatic latent image carrier through the focusing lens array (writing beam diameter was 40 μm). A transfer belt was used as the transfer member. Using a chart with a writing rate of 6%, continuous 100,000 sheets were printed (the test environment was 22 ° C.-55% RH).
The charging conditions were as follows.
Charging condition 1:
Applied voltage: -1500V (unexposed portion potential of the electrostatic latent image carrier is -800V)
Charging condition 2:
Applied voltage: -1400V (unexposed portion potential of electrostatic latent image carrier is -650V)
The following five evaluations were carried out after printing 150,000 sheets. The results are shown in Table 14. In the table, the electric field strength was obtained in the same manner as in Examples 1-27.
(Ii) Evaluation of dot formation state: Halftone (one dot image) was output, the dot formation state was enlarged and observed, and rank evaluation was performed for dot reproducibility and dot scattering state.
(Iii) Dot outline: The sharpness of the periphery (edge) of the dot was evaluated.
(Iv) Evaluation of color reproducibility: After the initial state of the electrostatic latent image carrier and 150,000 sheets running, the same full color image was output, and evaluation of color reproducibility was attempted.
In any case, the rank evaluation was performed in 4 stages, and very good ones were indicated by ◎, good ones were indicated by ○, slightly inferior ones were indicated by Δ, and very bad ones were indicated by ×.
(V) As other items, image density evaluation: a black solid image was output, and the solid image density was evaluated. In addition, a halftone image was output and the presence / absence of moiré was evaluated. The item (v) is shown in Table 14 only when a defect occurs.

<Verification of the lowest angle peak of the Bragg angle θ>
Finally, 7.3 ° which is the lowest angle peak of the Bragg angle θ, which is a feature of the titanyl phthalocyanine crystal used in the present invention, will be verified as to whether or not it is the same as the lowest angle 7.5 ° of known materials.

(Comparative Synthesis Example 9)
A titanyl phthalocyanine crystal was obtained in the same manner as in Comparative Synthesis Example 1 except that the crystal conversion solvent in Comparative Synthesis Example 1 was changed from methylene chloride to 2-butanone.
As in Comparative Synthesis Example 1, the XD spectrum of the titanyl phthalocyanine crystal produced in Comparative Synthesis Example 9 was measured. This is shown in FIG. From FIG. 21, the lowest angle in the XD spectrum of the titanyl phthalocyanine crystal produced in Comparative Synthesis Example 9 is 7.5 °, which is different from the lowest angle (7.3 °) of the titanyl phthalocyanine produced in Comparative Synthesis Example 1. It can be seen that it exists.

(Measurement Example 1)
A pigment prepared in the same manner as the pigment described in JP-A-61-239248 (having a maximum diffraction peak at 7.5 °) was used as the pigment obtained in Comparative Synthesis Example 1 (minimum angle 7.3 °). Mass% was added and mixed in a mortar, and the X-ray diffraction spectrum was measured as before. The X-ray diffraction spectrum of Measurement Example 1 is shown in FIG.

(Measurement example 2)
3% by mass of the pigment prepared in Comparative Synthesis Example 9 (minimum angle 7.5 °) prepared in the same manner as the pigment described in Patent Document 56 (having a maximum diffraction peak at 7.5 °) was added, The mixture was mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as before. The X-ray diffraction spectrum of Measurement Example 2 is shown in FIG.

In the spectrum of FIG. 20, it can be seen that there are two independent peaks at 7.3 ° and 7.5 ° on the lower angle side, and at least the peaks at 7.3 ° and 7.5 ° are different. . On the other hand, in the spectrum of FIG. 21, the low angle side peak exists only at 7.5 °, which is clearly different from the spectrum of FIG.
From the above, it can be seen that the minimum angle peak of 7.3 ° in the titanyl phthalocyanine crystal of the present invention is different from the 7.5 ° peak in the known titanyl phthalocyanine crystal.

  The image forming method of the present invention, the image forming apparatus for forming an image by the method, and the process cartridge reduce the side effects caused by using a small diameter beam having a diameter of 50 μm or less as a writing light source and take advantage of the advantages. Realizing higher image quality, even when used repeatedly, there are few occurrences of abnormal images, high quality images can be stably maintained, high image quality and high stability can be achieved, and long life can be realized. It is suitable for a low-speed to high-speed copying process, and can be applied to a wide range of applications from monochrome or full-color analog copying machines to page printers using LD or LED light for optical writing.

FIG. 1 is a schematic diagram of an optical carrier generation mechanism. FIG. 2 is a diagram showing that the dot diameter increases during charge transport. FIG. 3 is a diagram for explaining the electric field strength dependency in dot formation. FIG. 4 is a graph for explaining the electric field strength dependence of soiling. FIG. 5 is a conceptual cross-sectional view showing a configuration example of the intermediate layer lamination in a conventional electrophotographic electrostatic latent image carrier. FIG. 6 is a conceptual cross-sectional view showing a configuration example of the intermediate layer lamination in a conventional electrophotographic electrostatic latent image carrier. FIG. 7 is a schematic view for explaining the electrophotographic process and the image forming apparatus of the present invention. FIG. 8 is a schematic view for explaining the tandem full-color image forming apparatus of the present invention. FIG. 9 is a diagram for explaining a process cartridge for an image forming apparatus according to the present invention. FIG. 10 is a TEM image of amorphous titanyl phthalocyanine. The scale bar in the figure is 0.2 μm. FIG. 11 is a TEM image of titanyl phthalocyanine after crystallization. The scale bar in the figure is 0.2 μm. FIG. 12 is a TEM image of a titanyl phthalocyanine crystal that has undergone crystal conversion in a short time. The scale bar in the figure is 0.2 μm. FIG. 13 is a diagram showing the state of the dispersion when the dispersion time is short. FIG. 14 is a diagram showing the state of the dispersion when the dispersion time is long. FIG. 15 is a graph showing the average particle size and particle size distribution for the dispersions of FIGS. FIG. 16 is a diagram showing the layer structure of the electrostatic latent image carrier used in the present invention. FIG. 17 is a diagram showing a layer structure of another electrostatic latent image carrier used in the present invention. FIG. 18 is a view showing the layer structure of still another electrostatic latent image carrier used in the present invention. FIG. 19 is an XD spectrum of titanyl phthalocyanine synthesized in Comparative Synthesis Example 1. FIG. 20 is an XD spectrum of a dry powder of water paste. FIG. 21 is an XD spectrum of titanyl phthalocyanine synthesized in Comparative Synthesis Example 9. FIG. 22 is an XD spectrum of titanyl phthalocyanine used in Measurement Example 1. FIG. 23 is an XD spectrum of titanyl phthalocyanine used in Measurement Example 2.

Explanation of symbols

1 Electrostatic latent image carrier (electrostatic latent image carrier drum)
1K electrostatic latent image carrier for black 1Y electrostatic latent image carrier for yellow 1M electrostatic latent image carrier for magenta 2 static elimination lamp 2C charging member 2M charging member 2Y charging member 2K charging member 3 charging roller 3C laser light 3M laser Light 3Y Laser light 3K Laser light 4C Developing member 4M Developing member 4Y Developing member 4K Developing member 5 Image exposure unit 5C Cleaning member 5M Cleaning member 5Y Cleaning member 5K Cleaning member 6 Developing unit 6C Image forming element 6M Image forming element 6Y Image forming element 6K image forming element 7 transfer paper 9 registration roller 10 transfer conveying belt 11 transfer bias roller 11C transfer brush 11M transfer brush 11Y transfer brush 11K transfer brush 12 separation claw 13 pre-cleaning charger 14 fur brush 1 DESCRIPTION OF SYMBOLS 5 Cleaning blade 16 Transfer conveyance belt 17 Feed roller 18 Fixing device 31 Conductive support body 33 Intermediate | middle layer 35 Charge generation layer 37 Charge transport layer 101 Electrostatic latent image carrier 102 Charging means 103 Exposure means 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means 201 Conductive support 202 Filler dispersion layer 203 Resin layer 204 Photosensitive layer 205 Charge blocking layer 206 Moire prevention layer 207 Charge generation layer 208 Charge transport layer 209 Protective layer

Claims (34)

Using a charging process for charging the surface of the electrostatic latent image carrier with an electric field strength of 30 V / μm or more obtained by the following formula, and using a light source with a beam diameter of 50 μm or less on the electrostatic latent image carrier, An electrostatic latent image forming step for forming an electrostatic latent image; a developing step for developing the electrostatic latent image with toner to form a visible image; and a transferring step for transferring the visible image to a recording medium; An image forming method including a fixing step of fixing a transfer image transferred to a recording medium,
The electrostatic latent image carrier is formed by laminating at least a charge blocking layer, a moire preventing layer, and a photosensitive layer in this order on a conductive support,
The charge blocking layer is made of methoxymethylated nylon, and the film thickness is 0.5 μm or more and less than 2.0 μm,
In the photosensitive layer, the average particle diameter of primary particles is 0.25 μm or less, and the diffraction value of Bragg angle 2θ in an error range of ± 0.2 ° with respect to X-ray having a wavelength of 1.542 mm by CuKα ray is 27 A maximum value at .2 °, and at least maximum values at 7.3 °, 9.4 °, 9.6 °, and 24.0 °, and more than 7.3 °, 9.4. A titanyl phthalocyanine crystal having a maximum value of less than 0 ° and 26.3 °,
The titanyl phthalocyanine crystal has a maximum value of at least 7.0 ° to 7.5 ° as a diffraction value of a Bragg angle 2θ in an error range of ± 0.2 ° with respect to an X-ray having a wavelength of 1.542 mm by CuKα ray. In addition, after crystallizing amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having a half-width of 1 ° or more and an average particle diameter of 0.1 μm or less in an organic solvent in the presence of water, An image forming method characterized by being obtained by fractionating and filtering titanyl phthalocyanine crystals before the average particle diameter of primary particles exceeds 0.25 μm.
[Formula]
Electric field intensity (V / μm) = surface potential of unexposed portion of electrostatic latent image carrier (V) / photosensitive layer film thickness (μm)   The image forming method according to claim 1, wherein the photosensitive layer is formed by laminating a charge generation layer and a charge transport layer in this order on the moire prevention layer. The image forming method according to claim 1, wherein the charging step is a step using a scorotron charging member. The image forming method according to any one of claims 1 to 3, wherein the moire preventing layer contains an inorganic pigment and a binder resin, and a volume ratio of the inorganic pigment to the binder resin is 1/1 to 3/1. The image forming method according to claim 4, wherein the binder resin is a thermosetting resin. The image forming method according to claim 5, wherein the thermosetting resin is a mixture of an alkyd resin and a melamine resin. The image forming method according to claim 6, wherein a mixing ratio of the alkyd resin and the melamine resin is 5/5 to 8/2. The image forming method according to claim 4, wherein the inorganic pigment is titanium oxide. It is composed of two or more types of titanium oxides having different average particle diameters. When the average particle diameter of the largest titanium oxide is D1, and the average particle diameter of the smallest titanium oxide is D2, 0.2 <(D2 / D1) The image forming method according to claim 8, wherein ≦ 0.5. The image forming method according to claim 9, wherein D2 is 0.05 <D2 <0.2 μm. The mixing ratio of T1 and T2 is 0.2 ≦ T2 / (T1 + T2) ≦ 0.8 in terms of weight ratio, where T1 is the largest titanium oxide and T2 is the smallest titanium oxide. The image forming method according to any one of the above. The image forming method according to claim 1, wherein the titanyl phthalocyanine crystal does not contain a halide. The titanyl phthalocyanine crystal is obtained by crystallizing amorphous titanyl phthalocyanine or low-crystalline titanyl phthalocyanine and by the acid paste method, washed with ion-exchanged water, and the pH of the ion-exchanged water after washing is 6-8. And the specific conductivity of the ion-exchanged water is 8 μS / cm or less. 14. The image forming method according to claim 1, wherein the amount of the organic solvent used in crystallization is 30 times the amount of amorphous titanyl phthalocyanine or low-crystalline titanyl phthalocyanine by weight ratio. The image forming method according to claim 1, wherein the photosensitive layer contains a polycarbonate containing triarylamine in either the main chain or the side chain. The image forming method according to claim 1, further comprising a protective layer on the photosensitive layer. The protective layer has a specific resistance of 10 ¹⁰ The image forming method according to claim 16, comprising an inorganic pigment or metal oxide having an Ω · cm or more. The image forming method according to claim 16, wherein the protective layer contains a polymer charge transport material. The image forming method according to claim 16, wherein the protective layer contains a binder resin, and the binder resin has a crosslinked structure. The image forming method according to claim 19, wherein the crosslink structure of the binder resin has a charge transport site. 21. The protective layer is formed by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. The image forming method according to any one of the above. The image forming method according to claim 21, wherein the functional group of the tri- or higher functional radical polymerizable monomer is either an acryloyloxy group or a methacryloyloxy group. The image forming method according to any one of claims 21 to 22, wherein the molecular weight of the trifunctional or higher-functional radical polymerizable monomer is 250 times or less of the number of functional groups. The image forming method according to any one of claims 21 to 23, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure is an acryloyloxy group or a methacryloyloxy group. 25. The image forming method according to claim 21, wherein the functional group of the radically polymerizable compound having a monofunctional charge transporting structure is a triamylamine structure. 26. The image forming method according to claim 21, wherein the radical polymerizable compound having a monofunctional charge transport structure is at least one of the following structural formulas (1) and (2).
However, in the structural formulas (1) and (2), R ₁ Is a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, an alkoxy group,- COOR ₇ (However, R ₇ Is a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group or an optionally substituted aryl group), a halogenated carbonyl group or CONR ₈ R ₉ (However, R ₈ And R ₉ Represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other. Represents Ar) ₁ , Ar ₂ Represents a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ , Ar ₄ Represents a substituted or unsubstituted aryl group, which may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3. 27. The image forming method according to claim 21, wherein the radical polymerizable compound having a monofunctional charge transport structure is at least one of the following structural formula (3).
However, in the structural formula (3), o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, and Rb and Rc are substituents other than a hydrogen atom and have 1 to 6 carbon atoms. Represents an alkyl group, and a plurality of them may be different. s and t represent an integer of 0 to 3. Za represents a single bond, a methylene group, an ethylene group, or a group represented by the following general formula (4).
28. The image forming method according to claim 21, wherein the content of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure is 30 to 70% by mass with respect to the total amount of the protective layer. 29. The image forming method according to claim 21, wherein the content of the radical polymerizable compound having a monofunctional charge transporting structure is 30 to 70% by mass with respect to the total amount of the protective layer. 30. The image forming method according to claim 21, wherein the protective layer is cured by heating or light energy irradiation. An electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and the static Developing means for developing an electrostatic latent image with toner to form a visible image, transfer means for transferring the visible image to a recording medium, and fixing means for fixing the transferred image transferred to the recording medium An image forming apparatus,
An image forming apparatus that forms an image by the image forming method according to claim 1. 32. The image forming apparatus according to claim 31, wherein the transfer unit employs a direct transfer method in which a visible image is directly transferred to a recording medium. 33. The image forming element according to any one of claims 31 to 32, wherein a plurality of image forming elements each including an electrostatic latent image carrier, a charging unit, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit are arranged. The image forming apparatus described. An electrostatic latent image carrier, and electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and further developing the electrostatic latent image with toner. At least one selected from a developing unit that forms a visual image, a transfer unit that transfers the visible image to a recording medium, and a cleaning unit that removes toner remaining on the electrostatic latent image carrier is an image forming apparatus. 31. A process cartridge which is detachably attached to a main body and forms an image by the image forming method according to claim 1.