JP2010078818A - Coating liquid for forming charge generating layer, electrophotographic photoreceptor, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating liquid for forming a charge generating layer, with improved dispersion stability and suppressed degradation in electric characteristics. <P>SOLUTION: The coating liquid for forming a charge generating layer contains a crystalline phthalocyanine or its derivative the melt of which does not show liquid crystallinity, and a liquid crystalline phthalocyanine derivative the melt of which shows liquid crystallinity, wherein the liquid crystalline phthalocyanine derivative is added in such an amount as to suppress changes in the crystal form of the crystalline phthalocyanine or its derivative. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charge generation layer forming coating solution, an electrophotographic photoreceptor, and an image forming apparatus. More particularly, the present invention relates to a coating solution for forming a charge generation layer containing liquid crystalline phthalocyanine, an electrophotographic photosensitive member including a charge generation layer produced using the coating solution, and an image forming apparatus provided with the photosensitive member. .

2. Description of the Related Art An electrophotographic image forming apparatus (hereinafter also referred to as “electrophotographic apparatus” or “apparatus”) that forms an image using electrophotographic technology is widely used in copying machines, printers, facsimile machines, and the like.
In an electrophotographic apparatus, an image is formed through the following electrophotographic process.
First, a photosensitive layer of an electrophotographic photosensitive member (hereinafter also referred to as “photosensitive member”) provided in the apparatus is uniformly charged to a predetermined potential by a charger. Thereafter, the charged photosensitive layer is exposed to light such as a laser beam irradiated from the exposure unit according to the image information to form an electrostatic latent image on the photosensitive layer.
Developer is supplied from the developing means to the formed electrostatic latent image. The electrostatic latent image is developed by attaching colored fine particles called toner, which is a component of the supplied developer, to the surface of the photoreceptor. The developed electrostatic latent image is visualized as a toner image.

The formed toner image is transferred from the surface of the photosensitive member to a transfer material such as recording paper by a transfer unit. A desired image is formed by fixing the transferred toner image by a fixing unit.
The photoconductor includes a photoconductive material. Organic and inorganic materials are known as photoconductive materials. Among these, a photoreceptor using an organic photoconductive material (hereinafter also referred to as “organic photoreceptor”) has some problems in sensitivity, durability, environmental stability, and the like. However, organic photoreceptors have many advantages over photoreceptors using inorganic photoconductive materials in terms of toxicity, manufacturing costs, and material design freedom.
The organic photoreceptor also has an advantage that the photosensitive layer constituting the photoreceptor can be formed by an easy and inexpensive known method typified by a dip coating method.

As described above, the organic photoconductor has many advantages, and has gradually become the mainstream of the photoconductor.
In particular, the performance of organic photoreceptors has been remarkably improved by the development of function-separated photoreceptors in which a charge generation function and a charge transport function are assigned to different substances. In addition to the above-mentioned advantages of the organic photoconductor, the function-separated type photoconductor also has the advantage that a photoconductor having arbitrary characteristics can be produced relatively easily because the selection range of the material constituting the photosensitive layer is wide. is doing.

Here, in the exposure means, in particular, a light source of near-infrared light of 780 nm or red light of 650 nm is often used. Therefore, the photoconductor is required to have high sensitivity to light of these wavelengths. Crystalline phthalocyanine has been studied as a charge generation material for realizing such a highly sensitive photoreceptor.
There are various crystal forms of crystalline phthalocyanine. The crystal lattice spacing (plane spacing) of crystalline phthalocyanine is defined by the position of the diffraction peak in the X-ray diffraction spectrum. In addition, the crystal component in crystalline phthalocyanine has an approximate content defined by the relative intensity of the diffraction peak.
Here, it is known that a photoreceptor using crystalline phthalocyanine has greatly different electrical characteristics such as sensitivity, chargeability and dark decay depending on the crystal type. For this reason, various studies on crystal types suitable for photoconductors have been made. In particular, crystalline phthalocyanine is used for a charge generation layer in a function-separated type photoreceptor.

As the charge generation layer forming coating solution, a resin dispersion in which a charge generation material and a binder resin are mixed with an organic solvent is used. This coating liquid is known to change crystalline phthalocyanine to crystals having different sensitivities by long-term storage. The phthalocyanine in which the crystal has changed has a problem that it is not possible to obtain a photoreceptor having good sensitivity characteristics. Furthermore, when the combination of the binder resin and the organic solvent and their dispersion conditions are not appropriate, there also arises a problem that the crystalline phthalocyanine aggregates and precipitates.
Therefore, it is known that the storage stability (pot life stability, dispersion stability) of the coating liquid has a great influence on the performance and coating properties of the photoreceptor.
So far, as a method for improving the storage stability of the coating liquid, the development of a new charge generation material and the development of a binder resin and an organic solvent for dispersing the charge generation material are disclosed in JP-A-8-176456, JP-A-2004-145284 (new titanyl phthalocyanine) and JP-A-2000-98641 (binder resin) have been studied.

JP-A-8-176456 JP 2004-145284 A JP 2000-98641 A

  However, in the above publication, no examination has been made to sufficiently satisfy the dispersion stability and the electrical characteristics required for the organic photoreceptor, that is, the initial stability of the charging potential, the sensitivity, and the charge holding ability, and the dispersion stability is further improved. In addition, it has been desired to develop a coating solution for forming a charge generation layer having excellent electrical characteristics.

The inventors of the present invention have made extensive studies to solve the above problems, and as a result, by adding a liquid crystalline phthalocyanine derivative to the crystalline phthalocyanine or a derivative thereof, the crystal form change of the crystalline phthalocyanine or the derivative thereof Surprisingly, it was found that the dispersion stability can be improved, and a coating solution for forming a charge generation layer that suppresses deterioration of electrical characteristics has been developed.
Thus, according to the present invention, the melt includes a crystalline phthalocyanine or a derivative thereof that does not exhibit liquid crystallinity and a liquid crystal phthalocyanine derivative that exhibits a liquid crystallinity, and the liquid crystalline phthalocyanine derivative includes the crystalline phthalocyanine or A coating solution for forming a charge generation layer is provided, which is added in an amount capable of suppressing the crystal form change of the derivative.
In addition, according to the present invention, there is provided an electrophotographic photoreceptor including a charge generation layer produced using the charge generation layer forming coating solution.
Furthermore, according to the present invention, an image forming apparatus provided with the electrophotographic photosensitive member is provided.

According to the coating liquid for forming a charge generation layer of the present invention, dispersion stability can be improved, and deterioration of electric characteristics of the resulting charge generation layer can be suppressed.
The liquid crystalline phthalocyanine derivative is a phthalocyanine derivative represented by the general formulas (I) and (I) ′, and the crystalline phthalocyanine or a derivative thereof is a phthalocyanine or a derivative thereof represented by the general formula (II) or (II) ′. As a result, dispersion stability can be further improved, and deterioration of electrical characteristics can be suppressed.
Since the crystalline phthalocyanine or its derivative and the liquid crystalline phthalocyanine derivative are contained in the coating solution for forming the charge generation layer at a weight ratio of 100/10 to 100/1, the dispersion stability can be further improved, and the electrical characteristics Can be prevented.
Since the liquid crystalline phthalocyanine derivative is a phthalocyanine derivative represented by the general formula (I) a, it is possible to particularly suppress deterioration of electrical characteristics.

The crystalline phthalocyanine or derivative thereof has a temperature at which it transitions from a solid phase in the range of 200 to 450 ° C. to a liquid phase that is isotropic, and the liquid crystalline phthalocyanine derivative has a temperature from the solid phase in the range of 60 to 320 ° C. By having the temperature at which the phase transitions and the temperature at which the liquid crystal phase in the range of 200 to 450 ° C. transitions to the isotropic phase, the dispersion stability can be further improved and the deterioration of the electrical characteristics can be suppressed.
According to the present invention, it is possible to provide an electrophotographic photoreceptor in which deterioration of electrical characteristics is suppressed by including a charge generation layer produced using the charge generation layer forming coating liquid.
According to the present invention, it is possible to provide an image forming apparatus in which deterioration of electrical characteristics is suppressed by providing the electrophotographic photosensitive member.

(1) Charge generation layer forming coating liquid The charge generation layer forming coating liquid of the present invention includes crystalline phthalocyanine or a derivative thereof (hereinafter simply referred to as crystalline phthalocyanine) and a liquid crystalline phthalocyanine derivative (hereinafter simply referred to as liquid crystalline phthalocyanine). Is included). The liquid crystalline phthalocyanine is added in an amount capable of suppressing a change in crystal form of the crystalline phthalocyanine.
The reason why the dispersion stability of the coating liquid can be improved by adding the liquid crystalline phthalocyanine and the electrical property deterioration of the charge generation layer obtained from the coating liquid can be suppressed is unknown. However, the inventor presumes the reason as follows.

As a factor for lowering the dispersion stability, a change in crystal form or aggregation of crystalline phthalocyanine (charge generation material) due to a change in temperature of the coating liquid can be considered. Of course, it is necessary to keep the coating temperature as constant as possible, but slight environmental fluctuation (stimulation) causes stable crystal nucleation, and the crystal form gradually changes from the nucleus. it is conceivable that.
When liquid crystalline phthalocyanine is added, the charge generation material is affected by the liquid crystalline phthalocyanine (ie, π-conjugated interaction, intermolecular force) in addition to the interaction between them. Therefore, it is considered that the force that changes the crystal type acting between the charge generation materials is suppressed. As a result, it is considered that the crystal form change of the charge generating substance in the coating liquid hardly occurs and the dispersion stability is improved.

Crystalline phthalocyanine means phthalocyanine that exhibits crystallinity in a solid phase, does not exhibit a liquid crystal phase in a melt (liquid phase), and exhibits an isotropic phase. On the other hand, liquid crystalline phthalocyanine means phthalocyanine that exhibits a liquid crystal phase in a melt (liquid phase). More specifically, in crystalline phthalocyanine, the temperature at which the solid phase transitions to the isotropic liquid phase, that is, the melting point is preferably in the range of 200 to 450 ° C. from the viewpoint of the stability of the aggregated state. A more preferable melting point is in the range of 300 to 450 ° C. On the other hand, in the liquid crystalline phthalocyanine, the transition temperature from the solid phase to the liquid crystal phase, that is, the liquid crystal phase transition temperature is in the range of 60 to 320 ° C., and the transition temperature from the liquid crystal phase to the isotropic phase, that is, isotropic phase transition temperature. A range of 200 to 450 ° C. is preferable from the viewpoint of stability of the aggregated state. A more preferable liquid crystal phase transition temperature is in the range of 80 to 300 ° C, and an isotropic phase transition temperature is in the range of 300 to 450 ° C. Furthermore, the isotropic phase transition temperature is preferably 120 to 240 ° C. higher than the liquid crystal phase transition temperature.
Whether phthalocyanine is crystalline or liquid crystalline depends on the type, number and position of substituents constituting the phthalocyanine, the presence or absence of a central metal, and the like. Hereinafter, crystalline phthalocyanine and liquid crystalline phthalocyanine will be specifically described.

(Liquid crystalline phthalocyanine)
The liquid crystalline phthalocyanine has the following general formula (I) or (I) ′

(In the formula, Ra is an alkyl group, alkoxy group, haloalkyl group or haloalkoxy group having 4 to 10 carbon atoms, Rb is an alkyl group, alkoxy group, haloalkyl group or haloalkoxy group having 4 to 10 carbon atoms, M represents a copper atom, oxoaluminum or oxotitanium)
It is a phthalocyanine derivative shown by.
In the formula (I), examples of the alkyl group include alkyl groups having 4 to 10 carbon atoms, and alkyl groups having 8 to 10 carbon atoms such as octyl group and decyl group are preferable.
In the formula (I), examples of the alkoxy group include an alkoxy group having 5 to 10 carbon atoms, and an alkoxy group having 8 to 10 carbon atoms in an octyloxy group and a decyloxy group is preferable.
In formula (I), examples of the haloalkyl group include those in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.

In formula (I), examples of the haloalkoxy group include those in which at least one hydrogen atom in the alkoxy group is substituted with a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
In the formula (I), M is preferably oxotitanium from the viewpoint of obtaining a charge generation layer having good electrical characteristics.
In formula (I) ′, examples of the alkyl group include alkyl groups having 4 to 10 carbon atoms, and alkyl groups having 4 to 8 carbon atoms such as butyl group, pentyl group, hexyl group, heptyl group, and octyl are preferable.

In the formula (I) ′, examples of the alkoxy group include an alkoxy group having 4 to 10 carbon atoms, and an alkoxy group having 4 to 8 carbon atoms such as a butoxy group, a pentoxy group, a hexoxy group, a heptoxy group, and octoxy is preferable.
In formula (I) ′, examples of the haloalkyl group include those in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
In formula (I) ′, examples of the haloalkoxy group include those in which at least one hydrogen atom in the alkoxy group is substituted with a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
The phthalocyanine derivative of the formula (I) is further represented by the following general formula (I) a

(In the formula, Ra ′ represents an alkoxy group having 8 to 10 carbon atoms)
It is preferable that it is a phthalocyanine derivative shown by these.
The liquid crystalline phthalocyanine may be composed of one kind or a mixture of two or more kinds.
The liquid crystalline phthalocyanine can be synthesized by a known method such as the Wyler method. Specifically, compound (I) can be synthesized by heating and melting a phthalimide derivative having a corresponding Ra as a substituent and a metal as M in urea. Compound (I) ′ can be synthesized by heating and melting a phthalimide derivative having the corresponding Rb as a substituent in urea. The synthesized product can be purified by a known method such as column chromatography.
For example, a phthalocyanine in which M is oxotitanium can be easily obtained by reacting phthalonitrile, a soluble titanium compound and urea in a suitable solvent using the corresponding Ra as a substituent.

(Crystalline phthalocyanine)
As the crystalline phthalocyanine, any phthalocyanine used as a charge generating substance in this field can be used. For example, the following general formula (II) or (II) ′

(Wherein Xa is the same or different, halogen atom, alkyl group or alkoxy group having 1 to 3 carbon atoms, n is an integer of 0 to 4, M is a copper atom, tin atom, cobalt atom, hydroxy Aluminium, oxoaluminum or oxotitanium)
The phthalocyanine represented by these is mentioned.
In formulas (II) and (II) ′, examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
In formulas (II) and (II) ′, examples of the alkyl group include alkyl groups having 1 to 3 carbon atoms such as methyl, ethyl, propyl, and isopropyl groups.
In the formulas (II) and (II) ′, examples of the alkoxy group include an alkoxy group having 1 to 3 carbon atoms such as methoxy, ethoxy, propoxy, and isopropoxy group.
In the formulas (II) and (II) ′, n is preferably 0 from the viewpoint of electrical characteristics.

Of the above crystalline phthalocyanines, oxotitanium phthalocyanine or a derivative thereof in which M is oxotitanium is particularly preferred. Since oxotitanium phthalocyanine or a derivative thereof has high charge generation efficiency and charge injection efficiency, a large amount of charge can be generated by absorbing light. In addition, since the generated charges are difficult to accumulate in the molecule, the charges are efficiently injected into the charge transport material of the charge transport layer and smoothly transported. Therefore, a high-sensitivity and high-resolution photoconductor can be obtained.
The crystalline phthalocyanine may consist of one kind or a mixture of two or more kinds.

Crystalline phthalocyanine can be produced by a known method. For example, oxotitanium phthalocyanine or a derivative thereof, where M is oxotitanium, are described by Moser, Frank H and Arthur L., et al. Phthalocyanine Compounds by Thomas, Reinhold Publishing Corp. , New York, 1963.
More specifically, an unsubstituted oxotitanium phthalocyanine represented by the above general formula (II), where n is 0, is obtained by heating and melting phthalonitrile and titanium tetrachloride or by using a suitable material such as α-chloronaphthalene. It is obtained by synthesizing dichlorotitanium phthalocyanine by heating in a solvent and then hydrolyzing with base or water.
Alternatively, unsubstituted oxotitanium phthalocyanine can be produced by reacting isoindoline with titanium tetraalkoxide such as tetrabutoxytitanium in a suitable solvent such as N-methylpyrrolidone.

(Weight ratio of crystalline phthalocyanine to liquid crystalline phthalocyanine)
The weight ratio of crystalline phthalocyanine to liquid crystalline phthalocyanine is preferably 100/10 to 100/1. When the weight ratio of the liquid crystalline phthalocyanine is more than 100/10, the crystallinity change of the liquid crystalline phthalocyanine itself contributes to the sensitivity of the photosensitive member, so that the sensitivity may change over time when the coating liquid is stored. On the other hand, when the weight ratio of the liquid crystalline phthalocyanine is less than 100/1, the effect of adding the liquid crystalline phthalocyanine may not be obtained. The weight ratio is particularly preferably 100/5 to 100/2 from the viewpoints of dispersion stability and electrical characteristics.

(Other ingredients)
Examples of other components include a binder resin and a solvent.
(A) Binder Resin As the binder resin, any resin known in the art can be used. Specifically, vinyl resins such as polymethyl methacrylate, polystyrene, polyvinyl chloride, polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, polyphenylene oxide, etc. Thermoplastic resins: thermosetting resins such as phenoxy resins, epoxy resins, silicone resins, polyurethanes, phenol resins, alkyd resins, melamine resins, phenoxy resins, polyvinyl butyral, polyvinyl formal, partially crosslinked products of these resins, these resins Copolymer resins containing two or more of the structural units contained in (vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, acrylonitrile) - an insulating resin) such as styrene copolymer resin.

  The use ratio of the binder resin and the mixture of crystalline phthalocyanine and liquid crystalline phthalocyanine is not particularly limited. For example, when the weight of the mixture of crystalline phthalocyanine and liquid crystalline phthalocyanine is G and the weight of the binder resin is B, the ratio G / B is preferably 10/100 or more and 200/100 or less. When the ratio G / B is less than 10/100, the sensitivity of the photoreceptor may be lowered. On the other hand, if the ratio G / B exceeds 200/100, the film strength of the charge generation layer may be reduced. Further, the dispersibility of the crystalline phthalocyanine is lowered and the coarse particles are increased, so that the surface charge other than the portion to be erased may be reduced by exposure. This reduction may increase the fog of an image defect, particularly an image called “black spot” in which toner adheres to a white background and fine black spots are formed. The ratio G / B is particularly preferably 50/150 or more and 150/100 or less.

(B) Solvent The charge generation layer forming coating liquid usually contains a solvent. The solvent is not particularly limited as long as the binder resin, crystalline phthalocyanine and liquid crystalline phthalocyanine can be dissolved and / or dispersed.
Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; tetrahydrofuran (THF) and dioxane. , Ethers such as dibenzyl ether, dimethoxymethyl ether, and 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, and isophorone; esters such as methyl benzoate, ethyl acetate, and butyl acetate; and diphenyl sulfide Examples thereof include sulfur-containing solvents; fluorine-based solvents such as hexafluoroisopropanol; aprotic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide. These solvents can be used alone or in combination.
The solvent is preferably used in the range of 7000 to 15000 parts by weight when the total amount of the binder resin, crystalline phthalocyanine and liquid crystalline phthalocyanine is 100 parts by weight.

(Preparation method of coating liquid)
The coating liquid is not particularly limited, and can be prepared by dissolving and / or dispersing crystalline phthalocyanine and liquid crystalline phthalocyanine and optionally a binder resin in a solvent. From the viewpoint of dissolving and / or dispersing crystalline phthalocyanine and liquid crystalline phthalocyanine, and optionally a binder resin, as much as possible, it is preferable to stir for about 10 hours.

(2) Electrophotographic Photoreceptor The configuration of the electrophotographic photoreceptor of the present invention (hereinafter also referred to as “photoreceptor”) is not particularly limited as long as it has a charge generation layer. The charge generation layer is usually formed on a conductive support. The charge generation layer may also serve as a charge transport layer as a single-layer type photoreceptor, or may be provided separately from the charge transport layer as a laminated (function separation type) photoreceptor. Of these, a multilayer photoreceptor is preferred. The stacking order of the charge generation layer and the charge transport layer may be any of the order of the charge generation layer and the charge transport layer and the order of the charge transport layer and the charge generation layer from the conductive support side. Among these, the order of the charge generation layer and the charge transport layer is preferable from the viewpoint of durability.

1 and 2 are schematic cross-sectional views of the main part of an example of the photoreceptor of the present invention. 1 and 2 are schematic cross-sectional views of the main part of the photoreceptor in which the charge generation layer 12 and the charge transport layer 13 are laminated in this order from the conductive support 11 side.
The photoreceptor 1 in FIG. 1 is formed by laminating a charge generation layer 12 and a charge transport layer 13 in this order on the surface of a conductive support 11.
In the photoreceptor 2 of FIG. 2, an intermediate layer 14, a charge generation layer 12, and a charge transport layer 13 are laminated in this order on the surface of a conductive support 11.

(Conductive support)
The conductive support (photoconductor base tube) 11 serves as an electrode of the photoconductor, and the constituent material thereof is not particularly limited as long as it is a material used in this field.

Specifically, metal materials such as aluminum, aluminum alloy, copper, zinc, stainless steel, titanium: substrate surface made of polymer materials such as polyethylene terephthalate, polyamide, polyester, polyoxymethylene, polystyrene, hard paper, glass, etc. And metal foil laminated, metal material deposited, conductive polymer, tin oxide, indium oxide or other conductive compound layer deposited or coated.
The shape of the conductive support is not limited to a cylindrical shape, and may be a sheet shape, a columnar shape, an endless belt shape, or the like.

If necessary, the surface of the conductive support is irregularly reflected within a range that does not affect the image quality, such as anodized film treatment, surface treatment with chemicals, hot water, coloring treatment, and surface roughening treatment. Processing etc. may be given.
The irregular reflection treatment is particularly effective when the photoreceptor according to the present invention is used in an electrophotographic process using a laser as an exposure light source. That is, in the electrophotographic process using a laser as an exposure light source, the wavelength of the laser beam is uniform, so the laser beam reflected on the surface of the photoconductor and the laser beam reflected inside the photoconductor cause interference, Interference fringes due to this interference may appear in the image and cause image defects. Therefore, by performing irregular reflection processing on the surface of the conductive support, it is possible to prevent image defects due to interference of laser light having a uniform wavelength.

(Middle layer)
The photoreceptor of the present invention preferably has an intermediate layer 14 between the conductive support 11 and a laminated photosensitive layer comprising the charge generation layer 12 and the charge transport layer 13.
The intermediate layer has a function of preventing charge injection from the conductive support to the laminated photosensitive layer. That is, since the decrease in chargeability of the laminated photosensitive layer is suppressed, the decrease in surface charge other than the portion to be erased by exposure can be suppressed, so that the occurrence of image defects such as fog can be prevented. In particular, when an image is formed by the reversal development process, it is possible to prevent the occurrence of image fogging called black spots in which minute black dots made of toner are formed on a white background portion.
In addition, the intermediate layer covering the surface of the conductive support improves the film-formability of the multilayer photosensitive layer by reducing the degree of unevenness, which is a defect on the surface of the conductive support, and making the surface uniform. Therefore, the adhesion between the conductive support 11 and the laminated photosensitive layer can be improved.

  The intermediate layer 14 is prepared, for example, by dissolving a resin material in an appropriate solvent to prepare a coating liquid for forming an intermediate layer, applying the coating liquid on the surface of the conductive support to form a coating film, and drying the coating film. It can be formed by removing the solvent. Examples of the resin material include binder resins that can be used in the charge generation layer forming liquid. Moreover, as a solvent, the solvent which can be used with the said electric charge generation layer formation use liquid is mentioned. The drying is suitably performed at a temperature of about 50 to about 140 ° C., and a range of about 80 to about 130 ° C. is particularly preferable. If the drying temperature of the intermediate layer is less than about 50 ° C., the drying time may be prolonged, which may increase the manufacturing cost. On the other hand, when the drying temperature exceeds about 140 ° C., the electrical characteristics during repeated use are deteriorated, and the image obtained using the photoreceptor may be deteriorated.

Moreover, the coating liquid for intermediate | middle layer formation may contain the metal oxide particle.
The metal oxide particles can easily adjust the volume resistance value of the intermediate layer, can further suppress the injection of charge into the laminated photosensitive layer, and can maintain the electrical characteristics of the photoreceptor in various environments. The volume resistivity of the intermediate layer is preferably in the range of 10 ⁷ to 10 ^13. The volume resistance value is a value measured by a super insulation meter (SM8220, manufactured by Toa DKK Corporation).
Examples of the metal oxide particles include particles of titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide, and the like. The average particle diameter is preferably in the range of 0.02 to 0.5 μm. The average particle diameter is a value measured with an electron microscope.

When the total content of the resin material and metal oxide particles in the coating liquid for forming the intermediate layer is C and the content of the solvent is D, the weight ratio (C / D) of both is 1/99 to 40/60. Is preferable, and 2/98 to 30/70 is particularly preferable.
The weight ratio (E / F) of the resin material content (E) and the metal oxide particle content (F) is preferably 1/99 to 90/10, and preferably 5/95 to 70/30. Particularly preferred.

Although the film thickness of an intermediate | middle layer is not specifically limited, 0.01-20 micrometers is preferable. If the thickness of the intermediate layer is less than 0.01 μm, it may be difficult to function as the intermediate layer, and a uniform surface may not be obtained by covering defects of the conductive support. If the thickness of the intermediate layer exceeds 20 μm, it is difficult to form a uniform intermediate layer, and the sensitivity of the photoreceptor may be lowered. A more preferable film thickness is 0.05 to 10 μm.
When the constituent material of the conductive support is aluminum, the intermediate layer can be a layer containing alumite (alumite layer).

(Charge generation layer)
The charge generation layer 12 is formed of the coating liquid of the present invention and is composed of liquid crystalline phthalocyanine, crystalline phthalocyanine, and a binder resin.
The thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, particularly preferably 0.1 to 1 μm.
This is because if the film thickness of the charge generation layer is less than 0.05 μm, the efficiency of light absorption may be reduced and the sensitivity may decrease. Conversely, if the film thickness of the charge generation layer exceeds 5 μm, In this case, the charge transport in this process becomes a rate-determining step in the process of erasing the charge on the surface of the photoreceptor, and the sensitivity may be lowered.

  The charge generation layer can be formed by applying the charge generation layer formation on the surface of the conductive support or the intermediate layer to form a coating film, and drying the coating film to remove the solvent. The drying is suitably performed at a temperature of about 50 to about 140 ° C., and a range of about 80 to about 130 ° C. is particularly preferable. If the drying temperature of the charge generation layer is less than about 50 ° C., the drying time may be prolonged, which may increase the manufacturing cost. On the other hand, when the drying temperature exceeds about 140 ° C., the electrical characteristics during repeated use are deteriorated, and the image obtained using the photoreceptor may be deteriorated.

(Charge transport layer)
The charge transport layer 13 includes a charge transport material and a binder resin.
The charge transport material has a capability of accepting and transporting a charge generated by the charge generation material, and includes a material having a hole transport property and / or an electron transport property.

  As the hole transporting substance, a compound used in this field can be used. Specifically, carbazole derivatives, pyrene derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, many Ring aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives , Enamine derivatives, benzidine derivatives, polymers having groups derived from these compounds in the main chain or side chain (poly N- vinylcarbazole, poly-1-vinylpyrene, ethylcarbazole - formaldehyde resins, triphenylmethane polymers, poly-9-vinyl anthracene, etc.), polysilane and the like. These hole transport materials can be used alone or in combination of two or more.

  In addition, as the electron transporting substance, a compound used in this field can be used. Specific examples include benzoquinone derivatives, tetracyanoethylene derivatives, tetracyanoquinodimethane derivatives, fluorenone derivatives, xanthone derivatives, phenanthraquinone derivatives, phthalic anhydride derivatives, diphenoquinone derivatives, and the like. These charge transport materials can be used alone or in combination of two or more.

As the binder resin, the same binder resin as the charge generation layer forming use liquid can be used. The binder resin may be one kind or a mixture of two or more kinds.
Among the above resins, polystyrene, polycarbonate, polyarylate, and polyphenylene oxide are preferable because they have a volume resistance of 10 ¹³ Ω or more, excellent electrical insulation, and excellent film formability, potential characteristics, and the like. It can be used suitably.

The use ratio of the charge transport material and the binder resin is not particularly limited as long as it functions as a charge transport layer, but when the weight of the charge transport material is T and the weight of the binder resin is B, the ratio T / B is preferably 10/30 or more and 10/12 or less.
When the ratio T / B is less than 10/30 and the ratio of the binder resin is large, when the charge transport layer is formed by the dip coating method, the carrier mobility of the charge transport layer is lowered and the sensitivity of the photoreceptor is lowered. There is. On the other hand, if the ratio T / B exceeds 10/12 and the binder resin ratio decreases, the printing durability of the charge transport layer decreases and the amount of film loss due to repeated use increases. May decrease.

In addition to the two essential components, the charge transport layer may contain the same components as those contained in the charge generation layer, if necessary.
The thickness of the charge transport layer 13 is not particularly limited, but is preferably 5 to 40 μm, and particularly preferably 10 to 30 μm. When the thickness of the charge transport layer is less than 5 μm, the charge holding ability on the surface of the photoreceptor may be lowered. On the contrary, when the thickness of the charge transport layer exceeds 40 μm, the resolution of the photoreceptor may be lowered.

  The charge transport layer can be formed by applying a charge transport layer forming coating solution on the surface of the conductive support or the intermediate layer to form a coating film, and drying the coating film to remove the solvent. The drying is suitably performed at a temperature of about 50 to about 140 ° C., and a range of about 80 to about 130 ° C. is particularly preferable. If the drying temperature of the charge transport layer is less than about 50 ° C., the drying time may be prolonged, which may increase the manufacturing cost. On the other hand, when the drying temperature exceeds about 140 ° C., the electrical characteristics during repeated use are deteriorated, and the image obtained using the photoreceptor may be deteriorated.

(Other layers)
A surface protective layer may be further provided on the charge transport layer. The surface protective layer can improve wear resistance and gas resistance.

(3) Image Forming Apparatus An image forming apparatus according to the present invention includes the above-described photoconductor, a charging unit that charges the photoconductor, an exposure unit that exposes the charged photoconductor, and an electrostatic formed by exposure. Developing means for developing the latent image and transfer means for transferring the electrostatic latent image to a transfer material are provided.
FIG. 3 shows a schematic side view of an example of the image forming apparatus (laser printer) of the present invention. Hereinafter, the image forming apparatus of the present invention will be described with reference to FIG. 3, but is not limited to the following description.

A laser printer 30 as an image forming apparatus includes a photosensitive member 1, a semiconductor laser (or light emitting diode) 31, a rotary polygon mirror 32, an imaging lens 34, a mirror 35, a charger 36 as a charging unit, and a developing unit as a developing unit. 37, a transfer paper cassette 38, a paper feed roller 39, a registration roller 40, a transfer charger 41 as a transfer means, a separation charger 42, a transport belt 43, a fixing device 44, a paper discharge tray 45, and a cleaner 46 as a cleaning means. Consists of including.
The semiconductor laser 31, the rotary polygon mirror 32, the imaging lens 34, and the mirror 35 constitute an exposure unit 49.

The photoreceptor 1 is mounted on the laser printer 30 so as to be rotatable in the direction of an arrow 47 by a driving unit (not shown). A laser beam 33 emitted from the semiconductor laser 31 is repeatedly scanned in the longitudinal direction (main scanning direction) with respect to the surface of the photoreceptor 1 by the rotary polygon mirror 32. The imaging lens 34 has f-θ characteristics, and the laser beam 33 is reflected by the mirror 35 to form an image on the surface of the photosensitive member 1 for exposure. By scanning the laser beam 33 as described above to form an image while rotating the photoconductor 1, an electrostatic latent image corresponding to image information is formed on the surface of the photoconductor 1.
The charger 36, the developing unit 37, the transfer charger 41, the separation charger 42, and the cleaner 46 are provided in this order from the upstream side to the downstream side in the rotation direction of the photosensitive member 1 indicated by an arrow 47.

  The charger 36 is provided upstream of the image forming point of the laser beam 33 in the rotation direction of the photosensitive member 1 and uniformly charges the surface of the photosensitive member 1. Therefore, the laser beam 33 exposes the surface of the photosensitive member 1 that is uniformly charged, and there is a difference between the charge amount of the part exposed by the laser beam 33 and the charge amount of the part not exposed. An electrostatic latent image is formed.

The charger 36 is arranged on the outer peripheral surface of the photoconductor 1 on the opposite side of the position where the transfer belt unit is arranged with the photoconductor 1 interposed therebetween.
The developing device 37 is provided on the downstream side in the rotation direction of the photosensitive member 1 with respect to the image forming point of the laser beam 33, supplies toner to the electrostatic latent image formed on the surface of the photosensitive member 1, and converts the electrostatic latent image into toner. Develop as an image.
The transfer paper 48 accommodated in the transfer paper cassette 38 is taken out one by one by the paper feed roller 39 and is given to the transfer charger 41 by the registration roller 40 in synchronism with the exposure of the photoreceptor 1. The toner image is transferred onto the transfer paper 48 by the transfer charger 41. A separation charger 42 provided in the vicinity of the transfer charger 41 discharges the transfer paper onto which the toner image has been transferred and separates it from the photoreceptor 1.

The transfer paper 48 separated from the photoreceptor 1 is conveyed to the fixing device 44 by the conveying belt 43, and the toner image is fixed by the fixing device 44. The transfer paper 48 on which the image is formed in this manner is discharged toward the paper discharge tray 45. In addition, after the transfer paper 48 is separated by the separation charger 42, the photoreceptor 1 that continues to rotate further cleans foreign matters such as toner and paper dust remaining on the surface by the cleaner 46. The photoreceptor 1 whose surface has been cleaned by the cleaner 46 is neutralized by a neutralizing lamp (not shown) provided together with the cleaner 46 and then further rotated, and a series of image forming operations starting from the charging of the photoreceptor 1 are repeated. .
In addition, it is possible to employ a configuration in which a plurality of photosensitive members are provided to form a superimposed image using a plurality of different toners. This configuration is called a tandem system.

The present invention will be specifically described below with reference to production examples, examples and comparative examples, but the present invention is not limited to these production examples, examples and comparative examples.
Production Example [Synthesis of 1,5,7,11,15.18,22,23-octakis (n-octadecylthio) phthalocyaninatooxotitanium (hereinafter referred to as liquid crystalline oxotitanium phthalocyanine)]
3,6-bis (n-octadecylthio) phthalonitrile (100 parts by weight), titanium butoxide (13.4 parts by weight), urea (6.3 parts by weight), 1-octanol (22.1 parts by weight) The mixture was heated and stirred at 160 ° C. for 8 hours under an atmosphere. After allowing to cool at room temperature (about 25 ° C.), the precipitate is filtered, separated and purified by a column, and recrystallized from a chloroform-acetone solvent, whereby 269.8 g of the final product is a liquid crystal represented by the following structural formula. Oxotitanium phthalocyanine (compound 1) was obtained (R = —O (CH ₂ ) ₇ CH ₃ ).

  In order to investigate the phase transition of the liquid crystalline oxotitanium phthalocyanine, observation was performed with a polarizing microscope. It was found that Compound 1 was a crystal up to 59 ° C., and the crystal melted at 59 ° C. to form a liquid crystal phase, and the liquid crystal phase transitioned to an isotropic phase at 284 ° C.

Example 1
As the conductive support, an aluminum cylindrical conductive support having an outer diameter of 30 mm and a length in the longitudinal direction of 340 mm was used.
100 parts by weight of titanium oxide (trade name: Taibake TTO55A, manufactured by Ishihara Sangyo Co., Ltd.), 100 parts by weight of alcohol-soluble copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.), 5320 parts by weight of methyl alcohol and 1,3-dioxolane A coating solution for forming an intermediate layer was prepared by dispersing 7998 parts by weight with a paint shaker for 10 hours. This intermediate layer forming coating solution was applied onto an aluminum cylindrical conductive support as a conductive support by a dip coating method and naturally dried to form an intermediate layer having a thickness of 1 μm.
Next, as a crystalline phthalocyanine, a titanyl phthalocyanine represented by the following structural formula (compound 2) produced by the method described in Japanese Patent No. 3567422

147 parts by weight, 3 parts by weight of liquid crystalline oxotitanium phthalocyanine (compound 1), 100 parts by weight of polyvinyl butyral resin (trade name: ESREC BM-2, manufactured by Sekisui Chemical Co., Ltd.) and 14,000 parts by weight of 1,3-dioxolane For 72 hours to prepare a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was applied to the surface of the intermediate layer previously provided and naturally dried to form a charge generation layer having a thickness of 0.1 μm. Compound 2 melted from the solid phase at 395 ° C. and transitioned to a liquid phase that is an isotropic phase.
Then, the following structural formula as a charge transport material

A coating solution for forming a charge transport layer is prepared by mixing 56 parts by weight of a butadiene compound (compound 3) and 100 parts by weight of a polycarbonate resin (trade name: TS2050, manufactured by Teijin Chemicals) with 613 parts by weight of tetrahydrofuran. Was prepared. This charge transport layer forming coating solution is applied to the surface of the charge generation layer previously provided in the same manner as the intermediate layer and dried at 130 ° C. for 1 hour to form a charge transport layer having a thickness of 30 μm. did.
Through the above steps, a multilayer photoreceptor having a multilayer structure in which an intermediate layer, a charge generation layer, and a charge transport layer are sequentially stacked on the conductive support shown in FIG. 2 was produced.

Example 2
Example 1 except that a coating solution for forming a charge generation layer comprising 136 parts by weight of crystalline phthalocyanine, 14 parts by weight of liquid crystalline oxotitanium phthalocyanine, 100 parts by weight of polyvinyl butyral resin and 14000 parts by weight of 1,3-dioxolane was used. In the same manner, a multilayer photoreceptor was produced.
Example 3
Except for using a coating solution for forming a charge generation layer comprising 148.5 parts by weight of crystalline phthalocyanine, 1.5 parts by weight of liquid crystalline oxotitanium phthalocyanine, 100 parts by weight of polyvinyl butyral resin, and 14000 parts by weight of 1,3-dioxolane. A laminated photoreceptor was produced in the same manner as in Example 1.
Example 4
Instead of liquid crystalline oxotitanium phthalocyanine, the following structural formula

A multilayer photoreceptor was prepared in the same manner as in Example 2 except that the liquid crystalline metal-free phthalocyanine represented by (Compound 4, manufactured by Aldrich) was used. Compound 4 was a crystal up to 140 ° C., and the crystal melted at 140 ° C. to form a liquid crystal phase, and the liquid crystal phase transitioned to an isotropic phase at 221 ° C.

Comparative Example 1
Example 1 except that liquid crystalline phthalocyanine was not used and a coating solution for forming a charge generation layer consisting of 150 parts by weight of crystalline phthalocyanine, 100 parts by weight of polyvinyl butyral resin and 14000 parts by weight of 1,3-dioxolane was used. In the same manner as above, a multilayer photoreceptor was produced.
Comparative Example 2
136 parts by weight of crystalline titanyl phthalocyanine, the following structural formula instead of liquid crystalline oxotitanium phthalocyanine

(In the formula, R ₁ is —O (CH ₂ ) ₇ CH ₃ , R ₂ is —O (CH ₂ ) ₁₁ CH ₃ )
Except for using the coating liquid for forming a charge generation layer comprising 14 parts by weight of oxotitanium phthalocyanine (compound 5) having no liquid crystal property, 100 parts by weight of polyvinyl butyral resin, and 14000 parts by weight of 1,3-dioxolane. A laminated photoreceptor was produced in the same manner as in Example 1. Compound 5 melted at 294 ° C. from the solid phase and transitioned to an isotropic liquid phase.
Compound 5 was synthesized in the same manner as Compound 1 except that only the starting phthalonitrile substituent was changed.

Example 5
Example 1 except that a coating solution for forming a charge generation layer comprising 125 parts by weight of crystalline phthalocyanine, 25 parts by weight of liquid crystalline oxotitanium phthalocyanine, 100 parts by weight of polyvinyl butyral resin and 14000 parts by weight of 1,3-dioxolane was used. In the same manner, a multilayer photoreceptor was produced.
Example 6
Other than using a coating solution for forming a charge generation layer comprising 149.5 parts by weight of crystalline phthalocyanine, 0.5 parts by weight of liquid crystalline oxotitanium phthalocyanine derivative, 100 parts by weight of polyvinyl butyral resin, and 14000 parts by weight of 1,3-dioxolane. Was a multilayer photoreceptor in the same manner as in Example 1.

(Evaluation method)
The stability of the charge generation layer coating solutions obtained in the examples and comparative examples was evaluated by the following methods.
(1) Crystalline type evaluation The charge generation layer forming coating solution prepared in Examples and Comparative Examples and the charge generation layer forming coating solution stored at 25 ° C./50% for 90 days were prepared, and each coating solution was immersed. A charge generation layer having a film thickness of 0.1 μm was formed by applying a glass substrate of 100 mm × 20 mm by a coating method and drying it naturally. The obtained charge generation layer was subjected to X-ray structural analysis under the following conditions. X-ray structural analysis of only titanyl phthalocyanine, which is crystalline phthalocyanine, was also conducted.
CuKα 1.5418Å
Voltage 30kV
Current 50mA
Start angle 5.0 °
Stop angle 30.0 °
Measurement method θ / 2θ method

From the X-ray diffraction spectrum of only titanyl phthalocyanine, which is a crystalline phthalocyanine, it was found that the resulting charge generation layer contained low crystalline titanyl phthalocyanine. Specifically, (1) the Bragg angle (2θ ± 0.2 °) shows a maximum intensity diffraction peak at 27.3 °, and (2) a plurality of Bragg angles between 9.0 ° and 10.0 °. (3) shows a broader diffraction peak at a Bragg angle of 24.0 ° compared to a diffraction peak of a Bragg angle of 27.3 °, and (4) a Bragg angle of 9.0 ° to 10.0 °. The peak intensity of each of the diffraction peaks in between and the diffraction peak with a Bragg angle of 24.0 ° is an amorphous pattern that is 25% or less of the diffraction peak intensity with a Bragg angle of 27.3 °, 6) The plurality of diffraction peaks between the Bragg angles 9.0 ° to 10.0 ° specifically include at least one of the Bragg angles 9.1 °, 9.3 °, and 9.5 °. It was found to be a low crystalline titanyl phthalocyanine composition.
Focusing on the peaks at 9.1 °, 9.3 °, and 9.5 ° as the criteria for determining the crystal type change, it was examined whether peak disappearance and peak shift occurred due to storage of the coating solution.
<Criteria>
A: There is almost no change in the X-ray diffraction spectrum.
○: The peak intensity ratios of 9.1 °, 9.3 °, and 9.5 are different.
X: The peaks at 9.1 °, 9.3 °, and 9.5 disappear and are shifted to the wide angle side.

(2) Evaluation of sedimentation degree 18 ml of the coating solution for forming a charge generation layer of Examples and Comparative Examples was put into a 20 ml test tube and allowed to stand at 25 ° C./50% for 180 days. The reduction rate ΔH of the height of the settling portion is defined as the settling degree.
<Criteria>
A: ΔH ≦ 1%
○: 1% <ΔH ≦ 5%
×: ΔH> 5%

(3) Evaluation of Sensitivity (Electrical Properties) Similar to Examples and Comparative Examples from each of the photoreceptors of Examples and Comparative Examples, and coating liquids in which the coating liquids of Examples and Comparative Examples were allowed to stand at 25 ° C./50% for 180 days Each of the photoconductors prepared in 1) was mounted on a digital copying machine (model: MX-2300, manufactured by Sharp Corporation) modified for testing so that the developing device and the surface potential measuring device could be replaced. The developing unit was removed from the test copying machine, and a surface potential meter (trade name: model 344, manufactured by Trek Japan Co., Ltd.) for measuring the surface potential of the photoreceptor in the image forming process was provided instead at the development site. Using this copying machine, the surface potential of the photoconductor when it was not exposed to laser light in a normal temperature / normal humidity (N / N) environment at a temperature of 25 ° C. and a relative humidity of 50% was measured. Adjusted to -600V. In this state, the surface potential of the photosensitive member when exposed by laser light (energy 0.2 and 0.5 μJ / cm ² ) was set to exposure potentials VH (V) and VL (V). Differences between VH (V) and VL (V) before and after standing were set as ΔVH (V) and ΔVL (V), respectively.
<Criteria>
A: Both ΔVH (V) and ΔVL (V) are 10 V or less. ○: Either ΔVH (V) or ΔVL (V) is larger than 10 V and 20 V or less. X: Either ΔVH (V) or ΔVL (V) is Greater than 20V
(Evaluation results)
The results are shown in Table 1.

From the results of the crystal type evaluation and the sedimentation degree evaluation using the X-ray diffraction spectrum, from Example 1 and Comparative Example 2, in the coating liquid for forming a charge generation layer to which liquid crystalline phthalocyanine was added, the crystal type hardly changed, and the precipitation It can be seen that the storage stability is high because the degree is small. Therefore, in the present invention, it can be said that the deterioration of the electrical characteristics due to long-term storage is reduced by achieving the suppression of the crystal form change and the improvement of the dispersion stability of the coating solution for forming the charge generation layer.
Furthermore, from Example 1 and Comparative Example 2, in order to obtain a sufficient effect of the present invention, it is necessary that the phthalocyanine derivative added to the charge generation layer forming coating liquid has liquid crystallinity. Recognize.
Further, from Examples 1 to 3 and Examples 5 to 6, it is found that the content ratio of the crystalline phthalocyanine and the liquid crystalline phthalocyanine derivative in the coating solution for charge generation layer is preferably 100/10 to 00/1.

Further, from comparison between Example 1 and Example 4, it can be seen that the central metal of the liquid crystalline phthalocyanine derivative is preferably oxotitanium.
As described above, by adding liquid crystalline phthalocyanine to the coating solution for forming the charge generation layer, the crystalline phthalocyanine, which is a charge generation material, can be suppressed in crystal form and dispersed stably, and electrical characteristics can be deteriorated by long-term storage. An electrophotographic photosensitive member in which the above was suppressed could be obtained.

  According to the present invention, by adding liquid crystalline phthalocyanine to a coating solution for forming a charge generation layer, the coating composition for forming a charge generation layer having excellent suppression of crystal form change and dispersion stability of crystalline phthalocyanine, which is a charge generation material. It is possible to produce an electrophotographic photosensitive member capable of producing a liquid and suppressing deterioration of electrical characteristics due to long-term storage.

FIG. 3 is a schematic cross-sectional view of a main part of the multilayer photoconductor of the present invention. FIG. 3 is a schematic cross-sectional view of a main part of the multilayer photoconductor of the present invention. 1 is a schematic side view of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Photoconductor 11 Conductive support 12 Charge generation layer 13 Charge transport layer 14 Intermediate layer 30 Laser printer (image forming apparatus)
DESCRIPTION OF SYMBOLS 31 Semiconductor laser 32 Rotating polygon mirror 33 Laser beam 34 Imaging lens 35 Mirror 36 Charger 37 Developing device 38 Transfer paper cassette 39 Paper feed roller 40 Registration roller 41 Transfer charger 42 Separation charger 43 Conveyor belt 44 Fixing device 45 Paper discharge Tray 46 Cleaner 47 Arrow 48 Transfer paper 49 Exposure means

Claims (7)

  The melt includes a crystalline phthalocyanine or a derivative thereof that does not exhibit liquid crystallinity and a liquid crystalline phthalocyanine derivative that exhibits a liquid crystallinity, and the liquid crystalline phthalocyanine derivative exhibits a change in crystal form of the crystalline phthalocyanine or a derivative thereof. A coating solution for forming a charge generation layer, which is added in an amount that can be suppressed. The liquid crystalline phthalocyanine derivative is represented by the following general formula (I) or (I) ′:

(In the formula, Ra is an alkyl group, alkoxy group, haloalkyl group or haloalkoxy group having 4 to 10 carbon atoms, Rb is an alkyl group, alkoxy group, haloalkyl group or haloalkoxy group having 4 to 10 carbon atoms, M represents a copper atom, oxoaluminum or oxotitanium)
A phthalocyanine derivative represented by
The crystalline phthalocyanine or a derivative thereof is represented by the following general formula (II) or (II) ′

(Wherein Xa is the same or different, halogen atom, alkyl group or alkoxy group having 1 to 3 carbon atoms, n is an integer of 0 to 4, M is a copper atom, tin atom, cobalt atom, hydroxy Aluminium, oxoaluminum or oxotitanium)
The coating solution for forming a charge generation layer according to claim 1, which is a phthalocyanine represented by the formula:   2. The charge generation layer forming coating according to claim 1, wherein the crystalline phthalocyanine or a derivative thereof and a liquid crystalline phthalocyanine derivative are contained in the charge generation layer forming coating solution in a weight ratio of 100/10 to 100/1. liquid. The liquid crystalline phthalocyanine derivative has the following general formula (I) a

(In the formula, Ra ′ represents an alkoxy group having 8 to 10 carbon atoms)
The coating solution for forming a charge generation layer according to any one of claims 1 to 3, which is a phthalocyanine derivative represented by the formula:   The crystalline phthalocyanine or derivative thereof has a temperature at which it transitions from a solid phase in the range of 200 to 450 ° C. to a liquid phase that is isotropic, and the liquid crystalline phthalocyanine derivative has a solid phase in the range of 60 to 320 ° C. The coating liquid for forming a charge generation layer according to any one of claims 1 to 4, which has a temperature for transition from a liquid crystal phase to an isotropic phase in a range of 200 to 450 ° C.   An electrophotographic photosensitive member comprising a charge generation layer produced using the charge generation layer forming coating liquid according to claim 1.   An image forming apparatus comprising the electrophotographic photosensitive member according to claim 6.

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