JP2007199629A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor, having titanyl phthalocyanine crystals that is superior in dispersibility and storage stability in an organic solvent, and to provide an image forming apparatus. <P>SOLUTION: In the electrophotographic photoreceptor, a charge generating material, in a photosensitive layer contains at least the titanyl phthalocyanine crystals having a maximum peak at the Bragg angle 2θ±0.2°=27.2° in the CuKα characteristic X-ray diffraction spectrum and having one peak within a range of 270-400°C in the differential scanning calorimetric analysis, with the exception of a peak that is associated with the evaporation of adsorbed water, and a binder resin in the photosensitive layer contains two polyarylate resins of a specific structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an image forming apparatus and an image forming method, and in particular, an image capable of efficiently forming a high-quality image by mounting an electrophotographic photosensitive member containing a charge generator excellent in dispersibility in a photosensitive layer. The present invention relates to a forming apparatus and an image forming method using the same.

  Conventionally, as a photoconductor used in an image forming apparatus, a charge generating agent that generates a charge by light irradiation, a charge transporting agent that transports the generated charge, a binder resin that constitutes a layer in which these substances are dispersed, and the like Organic photoreceptors comprising these are widely used.

  Further, as the charge generating agent used in the above-mentioned organic photoreceptor, phthalocyanine pigments that are sensitive to light of infrared to near-infrared wavelengths irradiated from a semiconductor laser, an infrared LED or the like are widely used.

  In addition, such phthalocyanine pigments include metal-free phthalocyanine compounds, copper phthalocyanine compounds, titanyl phthalocyanine compounds, and the like depending on their chemical structures, and each phthalocyanine compound has various crystal forms depending on the production conditions. It is known to get.

  In the presence of a large number of phthalocyanine compound crystals having different crystal types as described above, when a photoconductor containing titanyl phthalocyanine having a Y-type crystal structure as a charge generating agent is produced, other crystal types of titanyl phthalocyanine are used. It is known that the electrical characteristics of the photoreceptor are improved as compared with the case where it is used.

  For example, titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) = 27.3 ° with respect to Cu—Kα ray in an X-ray diffraction spectrum, and an organic compound capable of forming a phthalocyanine ring; A method for producing a Y-type crystal obtained by reacting a compound with dialkylamino alcohol to which urea or ammonia is added under conditions of 130 ° C. for about 4 hours is disclosed (for example, Patent Document 1).

  In addition, a method for producing a Y-type crystal titanyl phthalocyanine compound obtained by reacting o-phthalonitrile and titanium tetrabutoxide directly without using a urea compound and reacting them at 215 ° C. for about 2 hours. Is disclosed (for example, Patent Documents 2 and 3).

  More specifically, a method for producing a titanyl phthalocyanine crystal having a peak in a CuKα characteristic X-ray diffraction spectrum in a predetermined range and having no temperature change peak in a range of 50 to 400 ° C. in differential scanning calorimetry is disclosed. Has been.

  On the other hand, Patent Document 4 uses a polyarylate resin (trade name “U-polymer”, manufactured by Unitika Ltd.) represented by the following formula (101) in order to improve the photosensitivity and durability of the photosensitive layer. An electrophotographic photosensitive member has been proposed.

JP-A-8-176456 (Example) Patent No. 3463032 (Claims) JP 2004-145284 (Claims) However, in the case of Patent Document 1, the manufactured titanyl phthalocyanine crystal having a Y-type crystal structure is likely to cause a crystal transition to a β-type or α-type crystal in a coating solution for a photosensitive layer. The problem was seen. For this reason, the storage stability of the photosensitive layer coating solution is poor, and as a result, there has been a problem that a photosensitive layer having good electrical characteristics cannot be formed stably.

  On the other hand, when the titanyl phthalocyanine crystal described in Patent Document 2 or Patent Document 3 is used, the crystal transition from the Y-type crystal in the coating solution for the photosensitive layer to the β-type crystal inferior in sensitivity characteristics can be suppressed. Dispersibility in the photosensitive layer was insufficient. As a result, there has been a problem that the charge generated from the charge generating agent cannot move efficiently and the sensitivity is still insufficient.

  Further, the polyarylate resin (101) described in Patent Document 4 has a problem that it is difficult to prepare a coating solution for forming a photosensitive layer because of low solubility in a solvent. Therefore, when the titanyl phthalocyanine crystal is dispersed in the polyarylate resin (101) described in Patent Document 4, there is a problem that the dispersibility of the titanyl phthalocyanine crystal becomes insufficient and the sensitivity becomes insufficient.

  Accordingly, the present inventors have conducted intensive studies in view of the above-described problems. As a result, the image forming apparatus uses titanyl phthalocyanine crystals having predetermined thermal characteristics and optical characteristics as a charge generating agent and is soluble in a solvent. The present inventors have found that a good image can be obtained by mounting a photoconductor provided with a photosensitive layer containing a polyarylate resin having a high polyarylate resin.

  That is, an object of the present invention is to provide a high-sensitivity electrophotographic photosensitive member by mounting an electrophotographic photosensitive member containing a charge generator excellent in dispersibility in the photosensitive layer, and to obtain a good image. An object of the present invention is to provide an image forming apparatus capable of performing the above.

According to the present invention, there is provided an electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer formed on the surface of the conductive substrate directly or via an intermediate layer,
The photosensitive layer contains at least a binder resin, a charge generation material, and a charge transport material, and the charge generation material has a Bragg angle of 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum. In the differential scanning calorimetry, the binder resin contains at least titanyl phthalocyanine crystal having one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water in the differential scanning calorimetry. Containing a repeating unit represented by the following general formula (1) and a polyarylate resin having a repeating unit represented by the following general formula (2): Problem can be solved.

(In the general formula (1), R ¹ and R ² are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ³ and R ⁴ are the same or different from each other and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less, and the substitution positions of the two carbonyl groups are in an ortho or meta relationship with each other on the benzene ring having the two carbonyl groups.

(In General Formula (2), R ⁵ and R ⁶ are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ⁷ and R ⁸ are the same or different from each other, and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less.)
That is, if the titanyl phthalocyanine crystal having such optical characteristics and thermal characteristics is used as a charge generator, and the electrophotographic photosensitive member further contains a polyarylate resin having a specific structure as a binder resin, the titanyl phthalocyanine crystal Since the dispersibility in the photosensitive layer is good, a good quality image can be formed.

Further, by using such titanyl phthalocyanine crystal as a charge generating agent, crystal transition to α-type crystals and β-type crystals in the photosensitive layer coating solution can be effectively suppressed. Therefore, since a coating solution for a photosensitive layer having excellent storage stability can be obtained, an electrophotographic photoreceptor capable of obtaining a high-quality image can be produced stably and inexpensively.
In forming the electrophotographic photosensitive member of the present invention, the content ratio of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) in the polyarylate resin is as follows. It is preferable that it is 90: 10-10: 90.

That is, when the content ratio of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) in the polyarylate resin is in the above-described range, good dispersibility is maintained. can do.
In forming the electrophotographic photosensitive member of the present invention, it is preferable that the titanyl phthalocyanine crystal does not have a peak at a Bragg angle 2θ ± 0.2 ° = 26.2 ° in the CuKα characteristic X-ray diffraction spectrum. .
That is, with this configuration, the transition of the titanyl phthalocyanine crystal to the β-type can be controlled over a long period of time, and the storage stability of the titanyl phthalocyanine crystal in an organic solvent is further improved. In forming the electrophotographic photosensitive member of the present invention, the titanyl phthalocyanine crystal recovered after the titanyl phthalocyanine crystal is immersed in an organic solvent for 7 days is at least a Bragg angle 2θ ± in the CuKα characteristic X-ray diffraction spectrum. It is preferable to have a maximum peak at 0.2 ° = 27.2 ° and no peak at 26.2 °.
That is, with this configuration, the crystal transition in the organic solvent can be more reliably controlled, and as a result, the quality of the titanyl phthalocyanine crystal having excellent storage stability can be determined quantitatively. .

  In forming the electrophotographic photoreceptor of the present invention, the organic solvent described above is at least one member selected from the group consisting of tetrahydrofuran, dichloromethane, toluene, 1,4-dioxane, and 1-methoxy-2-propanol. Is preferred.

  That is, by comprising in this way, when such an organic solvent is used as the organic solvent in the photosensitive layer coating solution, the stability of a specific titanyl phthalocyanine crystal can be determined more reliably.

Another aspect of the present invention includes an electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer formed directly or via an intermediate layer on the surface of the conductive substrate,
The photosensitive layer contains at least a binder resin, a charge generation material, and a charge transport material, and the charge generation material has a Bragg angle of 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum. In the differential scanning calorimetry, the binder resin contains at least titanyl phthalocyanine crystal having one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water in the differential scanning calorimetry. Contains a repeating unit represented by the following general formula (1) and a polyarylate resin having a repeating unit represented by the following general formula (2), and at least charging means, exposure means, and development around the electrophotographic photoreceptor. The image forming apparatus is characterized in that the means and the transfer means are sequentially arranged.

(In the general formula (1), R ¹ and R ² are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ³ and R ⁴ are the same or different from each other and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less, and the substitution positions of the two carbonyl groups are in an ortho or meta relationship with each other on the benzene ring having the two carbonyl groups.

(In General Formula (2), R ⁵ and R ⁶ are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ⁷ and R ⁸ are the same or different from each other, and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less.)
That is, the electrophotographic photoreceptor using the titanyl phthalocyanine crystal having a small crystal transition and excellent storage stability even when immersed in an organic solvent for a long period of time as a charge generator is provided. Thus, it is possible to stably obtain an image forming apparatus having good electrical characteristics and image characteristics.
In forming the image forming apparatus of the present invention, the process speed of the electrophotographic photosensitive member is preferably set to a value within the range of 100 to 250 mm / sec.

  That is, with this configuration, image formation can be performed at high speed, and image formation efficiency can be increased.

  Further, according to the image forming apparatus of the present invention, since the dispersibility of the titanyl phthalocyanine crystal as the charge generating agent in the photosensitive layer is good, the sensitivity and charging property in the photoreceptor are good even when repeatedly used. Can be held in a stable state.

[First Embodiment]
In the first embodiment of the present invention, the charge generation material has a maximum peak at a Bragg angle 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum, and in differential scanning calorimetry. A repeating unit containing at least titanyl phthalocyanine crystal having one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water, wherein the binder resin is represented by the following general formula (1) And a polyarylate resin having a repeating unit represented by the following general formula (2).

(In the general formula (1), R ¹ and R ² are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ³ and R ⁴ are the same or different from each other and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less, and the substitution positions of the two carbonyl groups are in an ortho or meta relationship with each other on the benzene ring having the two carbonyl groups.

(In General Formula (2), R ⁵ and R ⁶ are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ⁷ and R ⁸ are the same or different from each other, and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less.)
Hereinafter, the electrophotographic photosensitive member of the first embodiment will be described separately for each component.
1. Electrophotographic Photoreceptor In constituting the image forming apparatus of the present invention, the photoreceptor used may be either a single-layer type electrophotographic photoreceptor or a laminated electrophotographic photoreceptor. Hereinafter, the single layer type electrophotographic photosensitive member and the multilayer type electrophotographic photosensitive member will be described in detail.
1-1 Single Layer Type Electrophotographic Photoreceptor (1) Basic Configuration In constituting the image forming apparatus of the present invention, the electrophotographic photosensitive member is preferably a single layer type electrophotographic photosensitive member.

  As a basic configuration of such a single layer type electrophotographic photosensitive member, a single layer type electrophotographic photosensitive member 10 is configured by providing a single photosensitive layer 14 on a substrate 12 as shown in FIG. Is.

  The photosensitive layer 14 is formed by applying a coating solution in which a specific titanyl phthalocyanine crystal as a charge generating agent, an electron transport agent, a hole transport agent, a binder resin, and the like are dissolved or dispersed in a predetermined solvent. It can be formed by coating on top and drying.

  Such a single layer type electrophotographic photosensitive member 10 can be employed for any of positive and negative charging types, and the layer structure of the photosensitive member is simplified, so that productivity can be improved. Moreover, since there are few interfaces between layers, optical characteristics can be improved.

  Further, as shown in FIG. 1B, a photosensitive member 10 ′ in which a barrier layer 16 is formed between the conductive substrate 12 and the photosensitive layer 14 within a range not impairing the characteristics of the photosensitive member may be used. Further, as shown in FIG. 1C, a photosensitive member 10 ″ having a protective layer 18 formed on the surface of the photosensitive layer 14 may be used.

In such a single layer type electrophotographic photosensitive member, only one of the electron transport agent and the hole transport agent may be used as the charge transport agent.
(2) Charge generator (2) -1 Optical properties The titanyl phthalocyanine crystal constituting the present invention has a maximum optical characteristic of Bragg angle 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum. (First optical characteristic).

  In the CuKα characteristic X-ray diffraction spectrum, it is preferable that there is no peak at the Bragg angle 2θ ± 0.2 ° = 26.2 ° (second optical characteristic).

  Furthermore, in the CuKα characteristic X-ray diffraction spectrum, it is preferable that there is no peak at a Bragg angle 2θ ± 0.2 ° = 7.4 ° (third optical characteristic).

  The reason for this is that when the first optical characteristic is not provided, the dispersibility in the photosensitive layer for producing an electrophotographic photosensitive member is remarkably reduced as compared with a titanyl phthalocyanine crystal having such an optical characteristic. This is because there are cases. In other words, the dispersibility in the photosensitive layer can be improved by providing the first optical characteristic, more preferably the second optical characteristic and the third optical characteristic. Further, the titanyl phthalocyanine crystal has these characteristics, so that the stability of the crystal type in the organic solvent can be improved.

  The dispersibility of the titanyl phthalocyanine crystal in the photosensitive layer is an element necessary for forming a high-quality image. Details are described in the section of thermal characteristics.

  In addition, the stability of the titanyl phthalocyanine crystal in the organic solvent described above indicates that the crystal form of the titanyl phthalocyanine crystal in the photosensitive layer coating solution when the photosensitive layer coating solution for forming the photosensitive layer is produced. However, it is an element necessary for preventing crystal transition from the Y type having excellent electrical characteristics to the α type and β type having poor electrical characteristics.

  In addition, the titanyl phthalocyanine crystal recovered after being immersed in an organic solvent for 7 days has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum, and 26.2 It is preferable that there is no peak at °. The reason for this is that even when immersed in an organic solvent for 7 days, the titanyl phthalocyanine crystal can retain the above-described properties, thereby dispersibility of the titanyl phthalocyanine crystal in the photosensitive layer and crystal transition in the organic solvent. This is because it can be more reliably controlled.

  In addition, the immersion experiment evaluation in the organic solvent used as the reference | standard which evaluates the storage stability of a titanyl phthalocyanine crystal | crystallization is the same as the conditions which actually store the coating liquid for photosensitive layers for producing the electrophotographic photoreceptor, for example. It is preferable to carry out under conditions. Therefore, for example, it is preferable to evaluate the storage stability of titanyl phthalocyanine crystals in a closed system under conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50 to 60% RH.

  The organic solvent for evaluating the storage stability of the titanyl phthalocyanine crystal is at least one member selected from the group consisting of tetrahydrofuran, dichloromethane, toluene, 1,4-dioxane, and 1-methoxy-2-propanol. preferable.

The reason for this is that when such an organic solvent is used as the organic solvent in the coating solution for the photosensitive layer, the stability of the specific titanyl phthalocyanine crystal can be more reliably determined, and the specific titanyl phthalocyanine crystal and the charge transport agent can be determined. This is because the compatibility in the binder resin and the like is improved. Therefore, it is possible to form a photoconductor that exhibits the characteristics of specific titanyl phthalocyanine crystals and charge transfer agents more effectively, and to stably produce an electrophotographic photoconductor excellent in electrical characteristics and image characteristics. Because it can.
(2) -2 Thermal characteristics In addition, the specific titanyl phthalocyanine crystal constituting the present invention has a thermal characteristic within a range of 270 to 400 ° C in addition to the peak accompanying vaporization of adsorbed water in differential scanning calorimetry. It has two peaks.

  This is because, in addition to the optical characteristics described above, if the image forming apparatus uses titanyl phthalocyanine crystals having such thermal characteristics as a charge generator, the dispersibility of the titanyl phthalocyanine crystals in the photosensitive layer is improved. Therefore, it is possible to form a high-quality image that effectively suppresses the occurrence of exposure memory, black streaks, black spots, and the like.

  In addition, when the specific titanyl phthalocyanine crystal described above is used as a charge generating agent, crystal transition to α-type crystals and β-type crystals in the photosensitive layer coating solution can be effectively suppressed. Therefore, a photosensitive layer coating solution having excellent storage stability can be obtained, and an image forming apparatus capable of efficiently forming a high-quality image can be stably manufactured.

  Here, the reason why the titanyl phthalocyanine crystal having the above-described optical characteristics and thermal characteristics is excellent in dispersibility in the photosensitive layer will be described.

Since the crystal growth of the titanyl phthalocyanine crystal having the first optical characteristic tends to be suppressed as compared with other conventional titanyl phthalocyanine crystals, a crystal having a smaller particle size than the conventional titanyl phthalocyanine crystal is used. Tend to form. Therefore, the small crystal grain size improves the dispersibility in the photosensitive layer as compared with the conventional titanyl phthalocyanine crystal.
(2) -3 Structure of titanyl phthalocyanine compound The structure of the titanyl phthalocyanine compound is preferably a compound represented by the following general formula (3a).

  This is because the use of a titanyl phthalocyanine compound having such a structure not only can further improve the dispersibility of specific titanyl phthalocyanine crystals in the photosensitive layer, but also stabilizes the crystal form in the coating solution for the photosensitive layer. This is because it can be further improved.

  In particular, the structure of the titanyl phthalocyanine compound is preferably represented by the following general formula (3b). Among them, an unsubstituted titanyl phthalocyanine compound represented by the following formula (3) is particularly preferable.

  This is because the use of a titanyl phthalocyanine compound having such a structure makes it easier to produce a specific titanyl phthalocyanine crystal that is superior in terms of dispersibility in the photosensitive layer and stability of the crystal type in the coating solution for the photosensitive layer. This is because it can be manufactured.

(In the general formula (3a), X ¹ , X ² , X ³ and X ⁴ are each a substituent which may be the same or different, and are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a cyano group, or a nitro group. And the repeating numbers a, b, c and d each represent an integer of 1 to 4, and may be the same or different.

(In the general formula (3b), X represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a cyano group, or a nitro group, and the repeating number e represents an integer of 1 to 4.)

(2) -4 Other Charge Generating Agents Other charge generating agents may be used in combination in order to adjust the sensitivity region in the photoreceptor. Examples of other charge generating agents include, but are not limited to, powders of inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon, azo pigments, and bisazo compounds. Other than pigments, perylene pigments, ansanthrone pigments, titanyl phthalocyanine crystals of the present invention, conventional phthalocyanine pigments, indigo pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments 1 type, or 2 or more types, such as a pigment and dithioketopyrrolopyrrole pigment, are mentioned.
(2) -5 Addition amount The addition amount of the charge generator is preferably set to a value within the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the binder resin described later.

  This is because the charge generating agent can efficiently generate charges when the photosensitive member is exposed by setting the amount of the charge generating agent within the above range.

  That is, when the amount of the charge generator added is less than 0.1 parts by weight with respect to 100 parts by weight of the binder resin, the charge generation amount is insufficient to form an electrostatic latent image on the photoreceptor. Because there is. On the other hand, when the amount of the charge generating agent exceeds 50 parts by weight with respect to 100 parts by weight of the binder resin, it may be difficult to uniformly disperse in the photosensitive layer coating solution.

  Therefore, it is more preferable that the amount of the charge generator added to 100 parts by weight of the binder resin is set to a value within the range of 0.5 to 30 parts by weight.

  The amount of charge generator added is the amount of the titanyl phthalocyanine crystal added only when the specific titanyl phthalocyanine crystal constituting the present invention is used as the charge generator, and the titanyl phthalocyanine crystal and other charge generators When using together, it is the total addition amount of both.

In addition, when using together the titanyl phthalocyanine crystal | crystallization which comprises this invention, and another charge generating agent, it is preferable to add a small amount of another charge generating agent in the range which does not prevent the effect of the titanyl phthalocyanine crystal mentioned above. Specifically, it is preferable to add another charge generating agent in a proportion within the range of 100 parts by weight or less with respect to 100 parts by weight of the titanyl phthalocyanine crystal.
(3) Binder resin As the binder resin, in the electrophotographic photoreceptor, the polyarylate resin is used as a binder resin, and the repeating unit represented by the general formula (1) and the general formula (2) ).

In the repeating unit represented by the general formula (1), R ¹ and R ² are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms.

  Examples of the alkyl group having 3 or less carbon atoms include methyl, ethyl, n-propyl, isopropyl and the like. Preferably, methyl and ethyl are used.

In the repeating unit represented by the general formula (1), R ³ and R ⁴ are the same or different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms.

  Examples of the alkyl group having 3 or less carbon atoms include the same ones as described above, preferably methyl and ethyl.

  In the repeating unit represented by the general formula (1), the substitution positions of two carbonyl groups are in an ortho or meta relationship with each other on the benzene ring having the two carbonyl groups. The substitution positions of the two carbonyl groups may include both those in the ortho relationship and those in the meta relationship.

In the repeating unit represented by the general formula (2), R ⁵ and R ⁶ are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms.

  Examples of the alkyl group having 3 or less carbon atoms include the same ones as described above, preferably methyl and ethyl.

In the repeating unit represented by the general formula (2), R ⁷ and R ⁸ are the same or different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms.

  Examples of the alkyl group having 3 or less carbon atoms include the same ones as described above, preferably methyl and ethyl.

  In addition, the repeating unit represented by the general formula (1) in the polyarylate resin (hereinafter sometimes simply referred to as “repeating unit (1)”) and the repeating unit represented by the general formula (2) ( Hereinafter, the content ratio with “repeating unit (2)” is not particularly limited, but, for example, the substitution positions of two carbonyl groups in the repeating unit (1) are in an ortho relationship with each other. The molar ratio of the repeating unit (1) to the repeating unit (2) is preferably 90:10 to 10:90, and more preferably 80:20 to 20:80. For example, when the substitution positions of the two carbonyl groups of the repeating unit (1) are in a meta relationship with each other, the molar ratio of the repeating unit (1) to the repeating unit (2) is preferably 90: It is 10-10: 90, More preferably, it is 80: 20-20: 80.

As the binder resin, a conventional binder resin can be used in combination with the polyarylate resin. Examples of the binder resin include styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, styrene-acrylic copolymers, polyethylene, ethylene- Vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral Thermoplastic resins such as resins and polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other cross-linkable thermosetting resins, as well as epoxy-acrylates and urethanes Such as a photocurable resin such as acrylate and the like.
(4) Electron Transfer Agent (4) -1 Type As the electron transfer agent, any of various conventionally known electron transfer compounds can be used. In particular, benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, fluorenone compounds [for example, 2,4,7-trinitro-9-fluorenone, etc. ], Dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,4,7-trinitrofluorenone imine compound, ethylated nitrofluorenone imine compound, tryptoanthone Thrin compound, tryptoanthrin imine compound, azafluorenone compound, dinitropyridoquinazoline compound, thioxanthene compound, 2-phenyl-1,4-benzoquinone compound, 2- Electrons such as anion radical and cation salts of phenyl-1,4-naphthoquinone compounds, 5,12-naphthacenequinone compounds, α-cyanostilbene compounds, 4, '-nitrostilbene compounds, and benzoquinone compounds Inhalable compounds are preferably used. These may be used alone or in combination of two or more.

  In particular, the electron transport agents (ETM-1 to 15) represented by the following formulas (4) to (18) are all compatible with the titanyl phthalocyanine crystal as the present invention and have an electron transport ability. It is preferably used as an electron transport agent excellent in

(4) -2 Addition amount The addition amount of the electron transport agent is preferably set to a value within the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin, and within a range of 30 to 200 parts by weight. It is more preferable to set the value within the range. In addition, when using together an electron transport agent and the below-mentioned hole transport agent, it is preferable to make the total amount into the value within the range of 20-500 weight part with respect to 100 weight part of binder resin. More preferably, the value is within the range of 30 to 200 parts by weight.

Moreover, when using together an electron transport agent and the hole transport agent mentioned later, the addition amount of an electron transport agent is the value within the range of 10-100 weight part with respect to 100 weight part of hole transport agents, It is preferable to do.
(5) Hole Transport Agent (5) -1 Type As the hole transport agent, any of various conventionally known hole transport compounds can be used. In particular, benzidine compounds, phenylenediamine compounds, naphthylenediamine compounds, phenanthrylenediamine compounds, oxadiazole compounds [for example, 2,5-di (4-methylaminophenyl) -1,3,4-oxa Diazole etc.], styryl compounds [eg 9- (4-diethylaminostyryl) anthracene etc.], carbazole compounds [eg poly-N-vinylcarbazole etc.], organic polysilane compounds, pyrazoline compounds [eg 1-phenyl-3 -(P-dimethylaminophenyl) pyrazoline etc.], hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazols Compounds, triazole compounds, butadiene compounds, pyrene-hydrazone compounds, acrolein compounds, carbazole-hydrazone compounds, quinoline-hydrazone compounds, stilbene compounds, stilbene-hydrazone compounds, diphenylenediamine compounds, etc. Are preferably used. These may be used alone or in combination of two or more.

  In particular, the hole transporting agents (HTM-1 to 27) represented by the following formulas (19) to (45) are all compatible with the above-mentioned titanyl phthalocyanine crystal and have a hole transporting ability. It is preferably used as a hole transporting agent excellent in.

(5) -2 Addition amount The addition amount of the hole transfer agent is preferably set to a value within the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin. A value within the range is more preferable. In addition, when using together a positive hole transport agent and the above-mentioned electron transport agent, it is preferable to make the total amount into the value within the range of 20-500 weight part with respect to 100 weight part of binder resin. More preferably, the value is within the range of 30 to 200 parts by weight.
(6) Other Additives In addition to the above-described components, various additives such as a sensitizer, a fluorene compound, an ultraviolet absorber, a plasticizer, a surfactant, and a leveling agent are added to the photosensitive layer. Can also be added. In order to improve the sensitivity of the photoreceptor, sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.
(7) Substrate As the substrate on which the above-described photosensitive layer is formed, various conductive materials can be used. For example, substrates formed of metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, and the above-described metals are vapor-deposited Alternatively, a substrate made of a laminated plastic material, a glass substrate coated with aluminum iodide, tin oxide, indium oxide, or the like is exemplified.

  That is, it is only necessary that the substrate itself has conductivity or the surface of the substrate has conductivity. Further, it is preferable that the substrate has sufficient mechanical strength when used.

The shape of the substrate may be any of a sheet shape and a drum shape according to the structure of the image forming apparatus to be used.
(8) Manufacturing method In manufacturing a single-layer type photoreceptor, a binder resin, a charge generator, a hole transport agent, and, if necessary, an electron transport agent are added to a solvent and dispersed and mixed. And a photosensitive layer coating solution. That is, when a single layer type photoreceptor is formed by a coating method, a titanyl phthalocyanine crystal as a charge generating agent, a charge transport agent, a binder resin and the like together with a suitable solvent, a known method such as a roll mill, a ball mill, What is necessary is just to disperse and mix using an attritor, a paint shaker, an ultrasonic disperser, etc., adjust a dispersion liquid, apply | coat this by a well-known means, and to dry.

  Moreover, as a solvent for making the coating liquid for photosensitive layers, 1 type (s) or 2 or more types, such as tetrahydrofuran, a dichloromethane, toluene, 1, 4- dioxane, and 1-methoxy-2-propanol, are mentioned.

Furthermore, in order to improve the dispersibility of the charge transport agent and the charge generator and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent, and the like may be added to the photosensitive layer coating solution. (9) Method for producing titanyl phthalocyanine crystal In addition, the CuKα characteristic X-ray diffraction spectrum constituting the present invention has a maximum peak at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and a differential scanning calorific value. In the analysis, a method for producing a titanyl phthalocyanine crystal having one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water will be described.

Such a method for producing a titanyl phthalocyanine crystal preferably includes the following steps (a) to (b).
(A) With respect to 1 mol of o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof, titanium alkoxide or titanium tetrachloride has a value within a range of 0.40 to 0.53 mol. And a urea compound is added at a value in the range of 0.1 to 0.95 mole per mole of o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof. Steps of reacting and producing titanyl phthalocyanine compound (b) Step of producing titanyl phthalocyanine crystal by performing acid treatment on the titanyl phthalocyanine compound produced in step (a). The above description will be omitted as appropriate, and the method for producing the above-mentioned titanyl phthalocyanine crystal will be mainly described.
(9) -1 Production process of titanyl phthalocyanine compound As a production method of titanyl phthalocyanine compound, o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof as a production material of such a molecule, titanium It is preferable to react a alkoxide or titanium tetrachloride with a urea compound to produce a titanyl phthalocyanine compound.

  Here, the production method will be specifically described by taking the titanyl phthalocyanine compound represented by the formula (3) as an example.

  That is, when manufacturing the titanyl phthalocyanine compound represented by Formula (3), it is preferable to carry out according to the following reaction formula (1) or the following reaction formula (2). In the reaction formulas (1) and (2), as an example, titanium tetrabutoxide represented by the formula (47) is used as the titanium alkoxide.

  Therefore, as shown in the reaction formula (1), the o-phthalonitrile represented by the formula (46) is reacted with titanium tetrabutoxide as the titanium alkoxide represented by the formula (47), or the reaction formula ( As shown in 2), 1,3-diiminoisoindoline represented by the formula (48) is reacted with a titanium alkoxide such as titanium tetrabutoxide represented by the formula (47) to give a formula (3) It is preferable to manufacture the titanyl phthalocyanine compound represented by these.

  Titanium tetrachloride may be used instead of titanium alkoxide such as titanium tetrabutoxide represented by the formula (47).

  The addition amount of titanium alkoxide such as titanium tetrabutoxide represented by formula (47) or titanium tetrachloride is represented by o-phthalonitrile represented by formula (46) or a derivative thereof, or formula (48). It is preferable to make it a value within the range of 0.40-0.53 mol with respect to 1 mol of 1,3-diiminoisoindoline or its derivative.

  This is because the addition amount of titanium alkoxide such as titanium tetrabutoxide represented by formula (47) or titanium tetrachloride is changed to o-phthalonitrile represented by formula (46) or a derivative thereof, or formula (48). By adding an excess amount exceeding 1/4 molar equivalent to the 1,3-diiminoisoindoline represented or its derivative, interaction with the urea compound described later is effectively exhibited. It is. Such interaction will be described in detail in the section of the urea compound.

  Therefore, the addition amount of titanium alkoxide such as titanium tetrabutoxide represented by the formula (47) or titanium tetrachloride is changed to o-phthalonitrile represented by the formula (46) or 1,3 represented by the formula (48). -It is more preferable to set it as the value within the range of 0.43-0.50 mol with respect to 1 mol of diiminoisoindoline etc., and it is further set as the value within the range of 0.45-0.47 mol. preferable.

  Moreover, it is preferable to perform a process (a) in presence of a urea compound. The reason for this is that by using a titanyl phthalocyanine compound produced in the presence of a urea compound, the interaction between the urea compound and titanium alkoxide or titanium tetrachloride is exerted, so that specific titanyl phthalocyanine crystals can be efficiently obtained. It is because it can do.

  That is, such an interaction means that ammonia produced by the reaction between a urea compound and titanium alkoxide or titanium tetrachloride further forms a complex with titanium alkoxide or titanium tetrachloride, and these substances are represented by reaction formulas (1) and (2 ) Is a function that further promotes the reaction represented by. Then, by reacting the raw material under such a promoting action, a titanyl phthalocyanine crystal that hardly undergoes crystal transition can be efficiently produced even in an organic solvent.

  In addition, the urea compound used in step (a) is at least one member of the group consisting of urea, thiourea, O-methylisourea sulfate, O-methylisourea carbonate, and O-methylisourea hydrochloride. Is preferred.

  The reason for this is that by using such a urea compound as the urea compound in the reaction formulas (1) and (2), ammonia generated in the course of the reaction more efficiently forms a complex with titanium alkoxide or titanium tetrachloride. This is because such a substance further promotes the reactions represented by the reaction formulas (1) and (2).

  That is, this is because the ammonia produced by the reaction of titanium alkoxide or titanium tetrachloride as a raw material with a urea compound forms a complex compound with titanium alkoxide or the like more efficiently. Therefore, this complex compound further promotes the reactions represented by the reaction formulas (1) and (2).

  It has been found that such a complex compound is likely to be produced specifically when reacted under a high temperature condition of 180 ° C. or higher. Therefore, among nitrogen-containing compounds having a boiling point of 180 ° C. or higher, for example, quinoline (boiling point: 237.1 ° C.), isoquinoline (boiling point: 242.5 ° C.), or a mixture thereof (weight ratio 10:90 to 90:10). ) Is more effective to implement in.

  Therefore, it is more preferable to use urea among the above-described urea compounds because ammonia as a reaction accelerator and a complex compound resulting therefrom are more easily generated.

  In addition, the amount of urea compound used in step (a) is 0.1 to 0.95 mol relative to 1 mol of o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof. It is preferable to set the value within the range.

  This is because the above-described action of the urea compound can be more efficiently exhibited by setting the addition amount of the urea compound within the range.

  Therefore, the addition amount of the urea compound is set to a value within a range of 0.3 to 0.8 mol with respect to 1 mol of o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline or a derivative thereof. It is more preferable to set the value within the range of 0.4 to 0.7 mol.

  Examples of the solvent used in the step (a) include hydrocarbon solvents such as xylene, naphthalene, methylnaphthalene, tetralin, and nitrobenzene, and halogenated carbonization such as dichlorobenzene, trichlorobenzene, dibromobenzene, and chloronaphthalene. Alcohol solvents such as hydrogen solvents, hexanol, octanol, decanol, benzyl alcohol, ethylene glycol, and diethylene glycol, cyclohexanone, acetophenone, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Examples thereof include one or two or more arbitrary combinations of the group consisting of ketone solvents, amide solvents such as formamide, and acetamide, and nitrogen-containing solvents such as picoline, quinoline, and isoquinoline.

  In particular, in the case of a nitrogen-containing compound having a boiling point of 180 ° C. or higher, for example, quinoline or isoquinoline, ammonia produced by the reaction of titanium alkoxide or titanium tetrachloride as a raw material with a urea compound is more efficiently produced by titanium. This is a suitable solvent because it easily forms a complex compound with an alkoxide or the like.

  Moreover, it is preferable to make reaction temperature in a process (a) high temperature 150 degreeC or more. This is because when the reaction temperature is less than 150 ° C., particularly 135 ° C. or less, titanium alkoxide or titanium tetrachloride as a raw material reacts with a urea compound, and it becomes difficult to form a complex compound. Therefore, it becomes difficult for such a complex compound to further promote the reaction represented by the reaction formulas (1) and (2), and the titanyl phthalocyanine crystal which is difficult to undergo crystal transition even in an organic solvent is efficiently produced. This is because it becomes difficult to manufacture.

  Therefore, the reaction temperature in the step (a) is more preferably set to a value within the range of 180 to 250 ° C, and further preferably set to a value within the range of 200 to 240 ° C.

  Moreover, although the reaction time in a process (a) depends on reaction temperature, it is preferable to set it as the range of 0.5 to 10 hours. This is because when the reaction time is less than 0.5 hours, titanium alkoxide or titanium tetrachloride as a raw material reacts with a urea compound, and it becomes difficult to form a complex compound. Therefore, it becomes difficult for such a complex compound to further promote the reaction represented by the reaction formulas (1) and (2), and the titanyl phthalocyanine crystal which is difficult to undergo crystal transition even in an organic solvent is efficiently produced. This is because it becomes difficult to manufacture. On the other hand, when the reaction time exceeds 10 hours, it is economically disadvantageous or the produced complex compound may be reduced.

Therefore, the reaction time in step (a) is more preferably set to a value within the range of 0.6 to 3.5 hours, and further preferably set to a value within the range of 0.8 to 3 hours.
(9) -2 Manufacturing process of titanyl phthalocyanine crystal Next, it is preferable that the titanyl phthalocyanine crystal manufactured in the above-described process is subjected to an acid treatment as a post-treatment to obtain a titanyl phthalocyanine crystal.

  In addition, as a step before performing the acid treatment, the titanyl phthalocyanine compound obtained by the above-described reaction is added to a water-soluble organic solvent, and the mixture is stirred for a certain time under heating, and then at a temperature condition lower than that of the stirring treatment. It is preferable to perform a pre-acid treatment step in which the solution is allowed to stand for a certain period of time for stabilization.

  Examples of the water-soluble organic solvent used in the pre-acid treatment step include alcohols such as methanol, ethanol, and isopropanol, N, N-dimethylformamide, N, N-dimethylacetamide, propionic acid, acetic acid, and N-methyl. One type or two or more types such as pyrrolidone and ethylene glycol may be mentioned. Note that a water-insoluble organic solvent may be added to the water-soluble organic solvent in a small amount.

  Moreover, although the conditions of a stirring process are not specifically limited among the processes before an acid treatment, It is preferable to perform the stirring process for about 1 to 3 hours on the fixed temperature conditions of about 70-200 degreeC temperature range. Furthermore, the conditions for the stabilization treatment after the stirring treatment are not particularly limited, but are about 10 to 50 ° C., particularly preferably about 5 to 15 hours under a constant temperature condition of about 23 ± 1 ° C. It is preferable to stabilize by standing.

  Next, the acid treatment step is preferably carried out as follows. That is, after dissolving the titanyl phthalocyanine crystal obtained in the acid treatment pre-process described above in an acid, the solution is dropped into water and recrystallized, and then the obtained titanyl phthalocyanine crystal is dissolved in an alkaline aqueous solution. It is preferable to wash. Specifically, the obtained crude crystals are dissolved in an acid, this solution is dropped into ice-cooled water, stirred for a certain period of time, and then allowed to stand at a temperature within the range of 10 to 30 ° C. Crystallization is preferred. Next, it is preferable to stir at 30 to 70 ° C. for 2 to 8 hours in a non-aqueous solvent without drying and in the presence of water.

  In addition, as an acid used for acid treatment, it is preferable to use concentrated sulfuric acid, trifluoroacetic acid, sulfonic acid, etc., for example. This is because, by using such a strong acid for acid treatment, impurities can be sufficiently decomposed, while decomposition of specific titanyl phthalocyanine crystals can be suppressed. Therefore, a titanyl phthalocyanine crystal having higher purity and excellent crystal characteristics can be obtained.

  Further, as the alkaline aqueous solution used for the cleaning treatment, it is preferable to use a general alkaline aqueous solution such as an aqueous ammonia solution or an aqueous sodium hydroxide solution.

  This is because the environment of the crystal can be changed from acidic to neutral by washing the specific titanyl phthalocyanine crystal after the acid treatment with the aqueous alkali solution. As a result, the crystal can be easily handled in the next step, and the stability of the crystal can be improved.

Examples of the non-aqueous solvent for the stirring treatment include halogen solvents such as chlorobenzene and dichloromethane.
1-2 Laminated Photoreceptor (1) Basic Configuration As shown in FIG. 2A, the laminated photoreceptor 20 is a specific material as a charge generator on the substrate 12 by means of vapor deposition or coating. A charge generation layer 24 containing a titanyl phthalocyanine crystal is formed, and then a charge transport agent and a coating solution for a photosensitive layer containing a binder resin are applied onto the charge generation layer 24 and dried to charge transfer. It can be created by forming layer 22.

  In contrast to the structure described above, as shown in FIG. 2B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon.

  However, since the charge generation layer 24 is much thinner than the charge transport layer 22, for protection, the charge transport layer 22 is formed on the charge generation layer 24 as shown in FIG. It is more preferable to form

  The charge transport layer preferably contains either a hole transport agent or an electron transport agent.

  By comprising in this way, it is not necessary to consider especially the compatibility etc. of the above-mentioned titanyl phthalocyanine crystal and the charge transfer agent, etc., and the binder resin having good compatibility with the titanyl phthalocyanine crystal, and the solvent Etc. can be used to constitute the photosensitive layer. Therefore, the characteristics of the titanyl phthalocyanine crystal can be exhibited more effectively, and an electrophotographic photoreceptor excellent in electrical characteristics and image characteristics can be stably obtained.

  Regarding the thickness of the photoreceptor layer in the multilayer photoreceptor, the thickness of the charge generation layer is preferably set to a value within the range of 0.01 to 5 μm, and a value within the range of 0.1 to 3 μm. More preferably.

  In addition, as a substrate on which such a photoreceptor layer is formed, the same substrate as that of the single layer type photoreceptor described above can be used.

Further, as shown in FIG. 2C, it is also preferable to form an intermediate layer 25 on the substrate 12 in advance before forming the photosensitive layer including the charge generation layer 24 and the charge transport layer 22. The reason for this is that by providing such an intermediate layer 25, it is possible to prevent the charge on the substrate side from being easily injected into the photoreceptor layer, and to firmly bind the photoreceptor layer onto the substrate 22. This is because the above defects can be covered and smoothed.
(2) Types In constituting the multilayer photoconductor of the present invention, the types of charge generating agent, hole transporting agent, binder resin, and other additives are basically the same as those of the single-layer type photoconductor described above. The same contents can be used.
(3) Addition amount The addition amount of the charge generating agent used in the multilayer photoreceptor of the present invention is within the range of 5 to 1000 parts by weight with respect to 100 parts by weight of the binder resin constituting the charge generation layer. It is preferable to set it as a value, and it is more preferable to set it as a value within the range of 30 to 500 parts by weight.

  Moreover, the charge transport agent and the binder resin constituting the charge transport layer can be blended in various proportions within a range that does not inhibit charge transport and a range that does not crystallize. The amount of the charge transfer agent added is preferably set to a value in the range of 10 to 500 parts by weight with respect to 100 parts by weight of the binder resin so that the charges generated in step 1 can be easily transported It is more preferable to set the value within the range.

The charge transfer agent addition amount indicates the total of the electron transfer agent addition amount and the hole transfer agent addition amount, and only the electron transfer agent or the hole transfer agent is added. Indicates the amount of added charge transport agent alone.
(4) Manufacturing method Manufacturing methods such as a charge generation layer, a charge transport layer, and an intermediate layer are each obtained by dispersing and mixing a binder resin and other additives together with an appropriate dispersion medium using a known method. What is necessary is just to prepare the coating liquid for layers, and to apply | coat and dry by a well-known means next, respectively.

[Second Embodiment]
Hereinafter, the image forming apparatus and the image forming method using the same according to the present invention will be described separately for each component.
1. Basic Configuration and Image Forming Method As a basic configuration of the image forming apparatus in the first embodiment, a copying machine 30 as shown in FIG. 3 can be cited. The copying machine 30 includes an image forming unit 31, a paper discharge unit 32, an image reading unit 33, and a document feeding unit 34. The image forming unit 31 further includes an image forming unit 31a and a paper feeding unit 31b.

  Therefore, in the illustrated example, the document feeding unit 34 includes a document placing tray 34a, a document feeding mechanism 34b, and a document discharge tray 34c, and the document placed on the document placing tray 34a. Is fed to the image reading position P by the document feeding mechanism 34b and then discharged to the document discharge tray 34c.

  Then, when the original is sent to the original reading position P, the image reading unit 33 reads the image on the original using the light from the light source 33a. That is, an image signal corresponding to the image on the document is formed using an optical element 33b such as a CCD.

  On the other hand, recording sheets (hereinafter simply referred to as “sheets”) S stacked on the sheet feeding unit 31b are sent one by one to the image forming unit 31a. The image forming unit 31a is provided with a photoconductive drum 41 as an image carrier. Further, around the photoconductive drum 41, a charger 42, an exposure unit 43, a developing unit 44, and a transfer roller. 45 is arranged along the rotation direction of the photosensitive drum 41.

  Among these components, the photosensitive drum 41 is rotationally driven in the direction indicated by the solid line arrow in the drawing, and the surface thereof is uniformly charged by the charger 42. Thereafter, an exposure process is performed on the photosensitive drum 41 by the exposure device 43 based on the above-described image signal, and an electrostatic latent image is formed on the surface of the photosensitive drum 41.

  Based on the electrostatic latent image, the developing unit 44 attaches toner and develops it, thereby forming a toner image on the surface of the photosensitive drum 41. The toner image is transferred as a transfer image onto the sheet S conveyed to the nip portion between the photosensitive drum 41 and the transfer roller 45. Next, the sheet S to which the transferred image is transferred is conveyed to the fixing unit 47 and a fixing process is performed.

  Further, the sheet S after fixing is sent to the paper discharge unit 32. However, when performing post-processing (for example, stapling processing), the paper S is sent to the intermediate tray 32a and then post-processed. Is done. Thereafter, the sheet S is discharged to a discharge tray portion (not shown) provided on the side surface of the image forming apparatus. On the other hand, when no post-processing is performed, the sheet S is discharged to a discharge tray 32b provided below the intermediate tray 32a. The intermediate tray 32a and the paper discharge tray 32b are configured as a so-called in-body paper discharge unit.

  In the image forming apparatus of the second embodiment, it is preferable that the developing process is a simultaneous development cleaning method. That is, as shown in FIG. 4, the simultaneous development cleaning method omits the cleaning device and collects the transfer residual toner on the photosensitive member after transfer to the developing device as a developing step means in the developing step of the photosensitive member. It is a transfer-type image forming apparatus with a cleaner-less system that can be reused.

Usually, in such an image forming apparatus of a cleanerless system, it is difficult to completely collect paper dust and silica, and there is a case where paper dust and silica adhere to the photosensitive member in a relatively large amount. The problem that black streaks are likely to occur easily occurs. However, according to the image forming apparatus of the present invention, since the electrophotographic photosensitive member having a predetermined titanyl phthalocyanine crystal is mounted, the occurrence of black spots is effectively prevented even when the developing process is a simultaneous development cleaning method. be able to. Therefore, it is possible to provide an image forming apparatus that can be reduced in size, weight, and cost.
2. Process Speed In addition, it is preferable to set the process speed in the above-described electrophotographic photosensitive member to a value within the range of 100 to 250 mm / sec.

  This is because the image forming can be performed at a high speed and the image forming efficiency can be increased by setting the process speed of the photoconductor to a value within the range of 100 to 250 mm / sec. On the other hand, since the dispersibility of the titanyl phthalocyanine crystal as a charge generator in the photosensitive layer is good, the sensitivity and chargeability of the photoreceptor can be maintained in a good state even when repeatedly used. This is because it can.

  That is, by setting the process speed of the photoconductor to a value of 100 mm / sec or more, it is necessary to transport charges generated in the exposed portion of the photoconductor in the previous round more quickly.

  However, in the present invention, since the dispersibility of the titanyl phthalocyanine crystal as the charge generating agent in the photosensitive layer is good, the surface area of the entire titanyl phthalocyanine crystal increases. That is, the contact rate between the titanyl phthalocyanine crystal and the charge transport agent is improved, and the charge transport becomes efficient.

  Therefore, since the generated charges can be transported quickly, it is possible to maintain sufficient sensitivity even when the process speed of the photoconductor is 100 mm / sec or more.

  In addition, regarding the chargeability, the contact ratio between the titanyl phthalocyanine crystal and the charge transfer agent is improved in the photosensitive layer, so that it is possible to effectively suppress the charge generated during exposure from remaining in the photosensitive layer.

  On the other hand, if the process speed of such a photoconductor exceeds 250 mm / sec, the transport of electric charges may not be in time, or the life of the image forming apparatus may be shortened due to excessively high drum rotation speed. It is.

Therefore, the process speed of such a photoreceptor is more preferably set to a value within the range of 120 to 180 mm / sec, and further preferably set to a value within the range of 140 to 160 mm / sec.
3. Neutralizing Unit As the neutralizing unit constituting the image forming apparatus according to the present invention, a conventionally known neutralizing unit can be used. For example, a static elimination lamp, a static elimination charger or the like is used, and those used for an exposure light source, a charging means, etc. can be used.

  On the other hand, when configuring the image forming apparatus of the present invention, it is also preferable to be a static elimination-less type in which the static elimination means as described above is omitted.

  This is because by adopting a static elimination-less type in which the static elimination means is omitted, the image forming apparatus can be reduced in size and the number of parts can be reduced to reduce the cost. On the other hand, in the present invention, as already described in the section of the charge generating agent, since the dispersibility of the titanyl phthalocyanine crystal as the charge generating agent in the photosensitive layer is good, it is possible to effectively generate the exposure memory. This is because it can be suppressed.

  Further, as an advantage of adopting the static elimination-less type in which the static elimination means is omitted, there is an improvement in the charging potential and sensitivity repetition characteristics of the photoreceptor.

  That is, when a static elimination lamp is used as the static elimination means, the potential attenuation occurs in the photosensitive layer even during the static elimination process, so that a space charge is generated in the photosensitive layer portion, and the repetitive characteristics in the charging potential and the like change to change a constant image. This is because it may be difficult to form.

Therefore, in the present invention, since the exposure memory can be effectively suppressed even in the static elimination-less type in which the static elimination means is omitted, not only the image forming apparatus can be reduced in size and cost but also the static elimination means. It is also possible to improve the deterioration of the repetition characteristics due to the above.
4). Cleaning means Conventionally known cleaning means can be used as the cleaning means constituting the image forming apparatus according to the present invention. For example, the edge of a plate-like cleaning blade made of an elastic material such as urethane rubber is brought into pressure contact with the electrophotographic photosensitive member to scrape residual toner. The cleaning member is composed of a blade and a roller, and examples of the roller include a roller with an abrasive having an abrasive on its surface.

  On the other hand, in configuring the image forming apparatus of the present invention, it is also preferable to use a simultaneous development cleaning system configured as a part of the developing unit, not the independent cleaning unit as described above.

  This is because the image forming apparatus can be miniaturized and the cost can be further reduced by reducing the number of components by adopting a cleaning simultaneous cleaning method as the cleaning unit. On the other hand, in the present invention, as described above in the section of the charge generator, since the dispersibility of the titanyl phthalocyanine crystal as the charge generator in the photosensitive layer is good, the residual charge in the photosensitive layer is small. This is because it is possible to prevent the residual toner from firmly adhering to the surface of the photoreceptor.

  Furthermore, by adopting the simultaneous development cleaning method and simplifying the cleaning process, problems in the conventional cleaning method using a cleaning blade can be improved. Such problems include filming of toner components and the like on the surface of the photoconductor, a decrease in the adhesion of the cleaning blade to the surface of the photoconductor, leaning defects resulting therefrom, and electrostatic stability and durability of the photoconductor. Adverse effects on sex and the like.

Therefore, in the present invention, even if the cleaning unit is a simultaneous development cleaning system, it is possible to suppress the residual toner from firmly adhering to the surface of the photoconductor, thereby reducing the size and cost of the image forming apparatus. Not only can the reduction be achieved, but filming caused by the conventional cleaning means can also be improved.
5). Transfer Unit The transfer unit constituting the image forming apparatus of the present invention is preferably disposed in contact with the electrophotographic photosensitive member. This is because not only the transfer current can be kept low, but also the amount of ozone generated can be reduced as compared with the case where a non-contact type transfer means using a charger or the like is used. On the other hand, in the present invention, as already described in the section of the charge generating agent, since the dispersibility of the titanyl phthalocyanine crystal as the charge generating agent in the photosensitive layer is good, the current to the photosensitive member at the time of transfer is This is because the occurrence of black streaks and black spots can be prevented effectively.

  That is, as described in the first embodiment, black streaks and black spots occur due to current leakage to the photoconductor during transfer. However, current leak to the photoconductor is caused by non-contact transfer. It is more likely to occur when the contact type transfer means is used than when the means is used. However, in the present invention, the dispersibility of the titanyl phthalocyanine crystal in the photosensitive layer is good, so that even when such a contact type transfer means is used, the occurrence of black streaks and black spots is suppressed and a high quality image is formed. It can be done.

Hereinafter, based on an Example, this invention is demonstrated in detail.
(Synthesis Example 1) Production of titanyl phthalocyanine crystal (1) Production of titanyl phthalocyanine A In an argon-substituted flask, 22 g (0.17 mol) of o-phthalonitrile, 25 g of titanium tetrabutoxide (0.073 mol), 2.28 g (0.038 mol) of urea and 300 g of quinoline were added, and the temperature was raised to 150 ° C. while stirring. Next, after evaporating the steam generated from the reaction system, the temperature was raised to 215 ° C. while the reaction temperature was maintained, and the reaction was further continued for 2 hours while maintaining the reaction temperature.

After completion of the reaction, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out from the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. 24 g of a purple solid was obtained.
(2) Production of titanyl phthalocyanine crystal A (2) -1 Pre-acid treatment step 10 g of the blue-purple solid obtained in the production of the titanyl phthalocyanine compound described above was added to 100 ml of N, N-dimethylformamide and stirred. Then, the mixture was heated to 130 ° C. and stirred for 2 hours. Next, heating was stopped when 2 hours passed, and after cooling to 23 ± 1 ° C., stirring was stopped, and the liquid was allowed to stand in this state for 12 hours for stabilization treatment. Subsequently, the stabilized liquid was filtered off with a glass filter, and the obtained solid was washed with methanol and then vacuum-dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.
(2) -2 Acid treatment step 5 g of the crude crystal of titanyl phthalocyanine obtained in the above-mentioned pre-acid treatment step was added to 100 ml of concentrated sulfuric acid and dissolved. Next, this solution was added dropwise to ice-cooled water, stirred for 15 minutes at room temperature, and then allowed to stand at about 23 ± 1 ° C. for 30 minutes for recrystallization. Next, the liquid described above was filtered off with a glass filter, and the obtained solid was washed with water until the washing liquid became neutral, and then dispersed in 200 ml of chlorobenzene in the presence of water without drying. The mixture was heated to 0 ° C. and stirred for 10 hours. Next, after the liquid was filtered off with a glass filter, the obtained solid was vacuum dried at 50 ° C. for 5 hours to obtain 4.1 g of unsubstituted titanyl phthalocyanine crystals (blue powder) represented by the formula (3). Got.
(3) Optical characteristics and thermal characteristics (3) -1 CuKα characteristic X-ray diffraction spectrum measurement Further, 0.3 g of the obtained titanyl phthalocyanine within 60 minutes after production was dispersed in 5 g of tetrahydrofuran, and the temperature was 23 ± 1. After storing for 7 days in a closed system under the conditions of ° C. and relative humidity of 50 to 60% RH, the sample was filled in a sample holder of an X-ray diffractometer (RINT1100 manufactured by Rigaku Corporation) for measurement. The obtained results are shown in FIG.

The measurement conditions were as follows for both initial measurement and remeasurement.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
Start angle: 3.0 °
Stop angle: 40.0 °
Scanning speed: 10 ° / min (3) -2 Differential scanning calorimetry Differential scanning of the obtained titanyl phthalocyanine crystal using a differential scanning calorimeter (TAS-200 type, DSC8230D manufactured by Rigaku Corporation) Calorimetric analysis was performed. The measurement conditions are as follows.

FIG. 6 shows the obtained differential scanning calorimetry chart. One peak was observed at 296 ° C.
Sample pan: Aluminum heating rate: 20 ° C / min (4) Production of titanyl phthalocyanine crystal B Production of titanyl phthalocyanine crystal in the same manner as titanyl phthalocyanine crystal A, except that urea was not used when producing the titanyl phthalocyanine compound B did. The obtained results are shown in FIG. 7 and FIG.
(Synthesis Example 2) Production of polyarylate resin (1) Production of Resin-1 1,1-bis (3-methyl-4-hydroxyphenyl) ethane 48.5 g (0.20 mol), t-butylphenol 1.5 g (0.010 mol), 16.0 g (0.40 mol) of sodium hydroxide, and 1.1 liter of water were prepared to prepare an alkaline aqueous solution, and trimethylbenzylammonium chloride as a polymerization catalyst was further added. . The addition amount of the polymerization catalyst is adjusted to 0.5 mol% with respect to 1,1-bis (3-methyl-4-hydroxyphenyl) ethane, and after the addition of the polymerization catalyst, the alkaline aqueous solution is vigorously changed. Stir. On the other hand, 20.2 g (0.10 mol) of terephthaloyl chloride and 20.2 g (0.10 mol) of isophthaloyl chloride were dissolved in 0.75 liter of dichloromethane to prepare a dichloromethane solution.

  Next, the dichloromethane solution was added to the alkaline aqueous solution under stirring to initiate the polymerization reaction. The polymerization reaction was carried out for 3 hours under stirring, and the temperature of the reaction solution during the polymerization reaction was adjusted to 20 ° C. After 3 hours from the addition of the dichloromethane solution, acetic acid was added to the reaction solution to terminate the polymerization reaction, and the reaction solution was washed with water. Washing was repeated until the aqueous layer after separation became neutral.

  Next, the organic layer taken out from the reaction solution after washing with water is slowly added to methanol with stirring, and the precipitate is separated in a furnace and dried to obtain the following formula (1-1). The polyarylate resin (Resin-1) 60g which contains the repeating unit and the repeating unit shown by following formula (2-1) in the ratio of 50:50 was obtained.

(2) Production of Resin-2 Instead of 1,1-bis (3-methyl-4-hydroxyphenyl) ethane, 54.1 g of 2,2-bis (3-methyl-4-hydroxyphenyl) butane (0. 20 mol) was used in the same manner as in Synthesis Example 1, except that a repeating unit represented by the following formula (1-2) and a repeating unit represented by the following formula (2-2) were mixed with 50:50. 58 g of polyarylate resin (Resin-2) contained in a proportion of was obtained.

(3) Production of Resin-3 Instead of 1,1-bis (3-methyl-4-hydroxyphenyl) ethane, 51.3 g of 1,1-bis (3-methyl-4-hydroxyphenyl) propane (0. 20 mol) was used in the same manner as in Synthesis Example 1, except that a repeating unit represented by the following formula (1-3) and a repeating unit represented by the following formula (2-3) were mixed with 50:50. 61 g of polyarylate resin (Resin-3) contained in a proportion of was obtained.

(4) Production of Resin-4 Instead of 1,1-bis (3-methyl-4-hydroxyphenyl) ethane, 48.5 g (0.20 mol) of 2,2-bis (4-hydroxyphenyl) butane was used. Except having used, it processed like the synthesis example 1, and contains the repeating unit shown by following formula (1-4) and the repeating unit shown by following formula (2-4) in the ratio of 50:50. 58 g of polyarylate resin (Resin-4) was obtained.

(5) Production of Resin-5 Instead of using a combination of terephthaloyl chloride and isophthaloyl chloride, a combination of 20.2 g (0.10 mol) of terephthaloyl chloride and 20.2 g (0.10 mol) of phthaloyl chloride was used. In the same manner as in Synthesis Example 1, a polyarylate resin containing a repeating unit represented by the following formula (1-5) and a repeating unit represented by the following formula (2-5) in a ratio of 50:50 ( Resin-5) 29 g was obtained.

(6) Production of Resin-6 Instead of 1,1-bis (3-methyl-4-hydroxyphenyl) ethane, 54.1 g of 4,4-bis (4-hydroxyphenyl) -2-methylpentane (0. 20 mol) was used in the same manner as in Synthesis Example 1 except that the repeating unit represented by the following formula (ru1) and the repeating unit represented by the following formula (ru2) were contained in a ratio of 50:50. 50 g of polyarylate resin (Resin-6) was obtained.

Example 1
4 parts by weight of the obtained titanyl phthalocyanine crystal was mixed with 50 parts by weight of a hole transporting agent (HTM-1) represented by the formula (21) and an electron transporting agent (ETM-3) 30 represented by the formula (6). Part by weight and 100 parts by weight of (Resin-1) obtained in Synthesis Example 2 having a viscosity average molecular weight of 30,000, which is a binder resin, are mixed with 800 parts by weight of tetrahydrofuran using a ball mill for 50 hours. Then, a coating solution for the photosensitive layer was produced by dispersing.

  Next, this photosensitive layer coating solution was applied to an aluminum drum-shaped support having a diameter of 30 mm and a total length of 254 mm as a substrate by a dip coating method. Thereafter, heat treatment was performed at 100 ° C. for 40 minutes to produce an electrophotographic photoreceptor having a single-layer type photosensitive layer having a thickness of 25 μm.

  Moreover, the sensitivity of the photosensitive layer formed using the coating solution for photosensitive layers for a single-layer type photosensitive layer immediately after production was measured under the following conditions.

  That is, the produced electrophotographic photosensitive member was charged to a surface potential of +850 V by corona discharge using a drum sensitivity tester at room temperature and normal humidity (temperature: 20 ° C., humidity: 60%).

Next, the surface of the photoreceptor was irradiated with light having a wavelength of 780 nm and a monochromatic width of 20 nm using a bandpass filter at a light intensity of 1.0 μJ / cm ² for 40 msec. The surface potential 0.35 seconds after the start of exposure was measured as sensitivity and evaluated according to the following criteria. The obtained results are shown in Table 1.
○: Sensitivity is less than 120V.
X: The sensitivity is 120 V or less.

Examples 2-6
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that Resin-1 was changed to the binder resin shown in Table 1 in Example 1. The obtained results are shown in Table 1.

Comparative Example 1
The same procedure as in Example 1 was performed except that Resin-1 in Example 1 was changed to a polycarbonate resin (Resin-A) having a viscosity average molecular weight of 30,000.

Comparative Example 2
The same procedure as in Comparative Example 1 was performed except that phthalocyanine A in Comparative Example 1 was changed to phthalocyanine B.

Comparative Example 3
The same procedure as in Example 1 was conducted except that phthalocyanine A in Example 1 was changed to phthalocyanine B.

According to the electrophotographic photosensitive member of the present invention, the charge generation material of the present invention is a titanyl phthalocyanine crystal, and the titanyl phthalocyanine crystal has a peak having a predetermined Bragg angle in a CuKα characteristic X-ray diffraction spectrum and a differential. In scanning calorimetry, storage stability in an organic solvent can be sufficiently improved as compared with conventional titanyl phthalocyanine crystals by controlling to have one peak within a predetermined temperature range. It was.
Furthermore, since specific polyarylate was used as the binder resin, the dispersibility of titanyl phthalocyanine was improved, and good sensitivity was obtained.

    Therefore, various image forming apparatuses such as electrophotographic photoreceptors and copiers and printers using the titanyl phthalocyanine crystal thus manufactured not only improve good electrical characteristics and image characteristics, but also facilitate production management. Furthermore, it is expected to contribute significantly to the economic effect.

(A)-(c) is a figure provided in order to demonstrate the structure of a single layer type photoreceptor. (A)-(c) is a figure provided in order to demonstrate the structure of a laminated type photoreceptor. 1 is a diagram for explaining an image forming apparatus of the present invention. 1 is a diagram for explaining an image forming apparatus of the present invention. 2 is a CuKα characteristic X-ray diffraction spectrum of a titanyl phthalocyanine crystal (after storage in tetrahydrofuran for 7 days) used in Example 1 and the like. It is a differential scanning calorimetry chart in the titanyl phthalocyanine crystal | crystallization used in Example 1 grade | etc.,. 2 is a CuKα characteristic X-ray diffraction spectrum of a titanyl phthalocyanine crystal (after being stored in tetrahydrofuran for 7 days) used in Comparative Example 1 and the like. It is a differential scanning calorimetry chart in the titanyl phthalocyanine crystal | crystallization used by the comparative example 1 grade | etc.,.

Explanation of symbols

10: Single layer type photoreceptor 10 ': Single layer type photoreceptor 10 ": Single layer type photoreceptor 12: Conductive substrate 14: Photosensitive layer 16: Barrier layer 18: Protective layer 20: Multilayer type photoreceptor 20': Laminated photoreceptor 20 ″: laminated photoreceptor 22: charge transport layer 24: charge generation layer 25: intermediate layer

Claims (7)

An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer formed directly or via an intermediate layer on the surface of the conductive substrate,
The photosensitive layer contains at least a binder resin, a charge generation material, and a charge transport material, and the charge generation material has a Bragg angle of 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum. In the differential scanning calorimetry, the binder resin contains at least titanyl phthalocyanine crystal having one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water in the differential scanning calorimetry, Contains a repeating unit represented by the following general formula (1) and a polyarylate resin having a repeating unit represented by the following general formula (2).

(In the general formula (1), R ¹ and R ² are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ³ and R ⁴ are the same or different from each other and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less, and the substitution positions of the two carbonyl groups are in an ortho or meta relationship with each other on the benzene ring having the two carbonyl groups.

(In General Formula (2), R ⁵ and R ⁶ are different from each other and represent a hydrogen atom or an alkyl group having 3 or less carbon atoms. R ⁷ and R ⁸ are the same or different from each other, and represent a hydrogen atom or a carbon number. Represents an alkyl group of 3 or less.) The content ratio of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) in the polyarylate resin is 90:10 to 10:90. The electrophotographic photosensitive member according to claim 1.   3. The electrophotographic photoreceptor according to claim 1, wherein the titanyl phthalocyanine crystal does not have a peak at a Bragg angle 2θ ± 0.2 ° = 26.2 ° in the CuKα characteristic X-ray diffraction spectrum. .   The titanyl phthalocyanine crystal recovered after immersing the titanyl phthalocyanine crystal in an organic solvent for 7 days has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum, The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member has no peak at 26.2 °.   5. The electrophotographic photoreceptor according to claim 4, wherein the organic solvent is at least one member selected from the group consisting of tetrahydrofuran, dichloromethane, toluene, 1,4-dioxane, and 1-methoxy-2-propanol. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1, wherein at least a charging unit, an exposing unit, a developing unit, and a transfer unit are sequentially arranged around the electrophotographic photosensitive member. The image forming apparatus according to claim 6, wherein a process speed in the electrophotographic photosensitive member is set to a value within a range of 100 to 250 mm / sec.