JP4607034B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a single-layer electrophotographic photosensitive member in which a photosensitive layer contains at least a specific crystal type titanyl phthalocyanine and a specific charge transport material.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light has a remarkable improvement in print quality and reliability. This digital recording technology is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, it is expected that its demand will increase further in the future. In addition, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing.

  Electrophotographic photoreceptors used in these image forming apparatuses are roughly classified into organic photoreceptors and inorganic photoreceptors, but organic photoreceptors are easier to manufacture and less expensive than conventional inorganic photoreceptors, In recent years, it has been widely used because it has the advantages of various choices of photoconductor materials such as charge transport materials, charge generation materials, and binder resins, and a high degree of freedom in functional design.

The organic photoreceptor includes a single-layer photoreceptor in which a charge transport material (a hole transport material, an electron transport material) is dispersed in the same photosensitive layer together with a charge generation material, a charge generation layer containing the charge generation material, and a charge. There is a laminate type photoreceptor in which a charge transport layer containing a transport material is laminated.
Most of the laminated photoreceptors are negatively charged, and the positively charged laminated photoreceptor has not been put into practical use. The reason is that an electron transport material having excellent electron transport ability, low toxicity, and high compatibility with the binder resin has not been put into practical use.

  On the other hand, a single-layer photoconductor including a charge generation material and a charge transport material in a single photosensitive layer can be produced by a simple manufacturing process, has improved optical characteristics due to fewer layer interfaces, and electron transport. It has been attracting attention in recent years because it has positive and negative sensitivities by including a material and a hole transport material, and is particularly advantageous in that it can cope with positive charging with low ozone generation and excellent charging uniformity.

  In recent years, image forming apparatuses are required to be downsized and speeded up, and accordingly, a photosensitive member having high sensitivity is required. In general, a semiconductor laser (LD) or a light emitting diode (LED) is used as an exposure light source of a recent digital image forming apparatus, and the wavelength is mainly in the near infrared region of about 680 to 830 nm. Therefore, development of electrophotographic photoreceptors using phthalocyanines having high sensitivity in the near infrared region, in particular, titanyl phthalocyanine (TiOPc), as a charge generation material has been actively conducted.

Various crystal forms of titanyl phthalocyanine are known. Among them, as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of CuKα (wavelength 1.542 mm), the maximum is at least 27.2 °. It is known that a titanyl phthalocyanine crystal having a diffraction peak has a very high carrier generation function.
An electrophotographic photoreceptor using this highly sensitive crystal type titanyl phthalocyanine has been put to practical use in a laminated type, but an excellent one in a single layer type has not been obtained. This is a highly sensitive titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα. However, there is a problem that an abnormal image called a scumming image is likely to occur due to repeated use of the photoconductor, and this problem is particularly prominent when used for a single-layer photoconductor. Because.

  As described above, there is currently no single-layer photoconductor that does not produce an abnormal image such as scumming even when it is repeatedly used with high sensitivity by using very high sensitivity titanyl phthalocyanine as a charge generation material. .

  The present invention has been made in view of the above prior art, and an object of the present invention is to provide a single-layer photoconductor that does not cause abnormal images such as background stains even when used repeatedly with high sensitivity.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have at least a photosensitive layer provided on a conductive support, and the photosensitive layer has at least a characteristic X-ray (wavelength of 1.542 mm) of CuKα as a charge generation material. As a diffraction peak (± 0.2 °) with a Bragg angle 2θ, the maximum diffraction peak is at least 27.2 °, the peak is further at 26.3 °, and the peak intensity at 26.3 ° is 27. Electron characterized by comprising a single layer containing titanyl phthalocyanine in the range of 1 to 99% with respect to a peak intensity of 2 ° and an electron transport material represented by the following general formula (1) as a charge transport material It has been found that by using a photographic photoconductor, the sensitivity is high, and abnormal images such as background stains do not occur even when used repeatedly.

Since the electron transport material represented by the following general formula (1) used in the present invention has a very excellent electron transfer function, the high carrier generation function of titanyl phthalocyanine is fully utilized to obtain a highly sensitive photoconductor. be able to.
Generally, titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα is The crystal form changes to a crystal form having a maximum diffraction peak at 26.3 ° due to mechanical stress, but the crystal form used in the present invention is in the middle stage. As the crystal changes from the crystal form having the maximum diffraction peak at 27.2 ° to the crystal form having the maximum diffraction peak at 26.3 °, the peak at 26.3 ° increases, but the peak at 26.3 ° is usually large. As a result, the chargeability is improved, but the sensitivity is lowered.

  However, when combined with the electron transport material represented by the following general formula (1) in the single-layer photoreceptor of the present invention, the peak intensity at 26.3 ° is 1 to 99% of the peak intensity at 27.2 °. Even if it is increased to the extent, the sensitivity is hardly lowered and only the charging property is improved. In addition, the occurrence of soiling can be greatly reduced as compared with the case where the maximum diffraction peak is at 27.2 ° and the peak is not at 26.3 °.

  In particular, among the titanyl phthalocyanines having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα, Japanese Patent Application Laid-Open No. 2001-19871. It has the maximum diffraction peak at 27.2 ° described in the publication, and further has main peaks at 9.4 °, 9.6 °, and 24.0 °, and the diffraction at the lowest angle side. A titanyl phthalocyanine having a peak at 7.3 ° and no peak between the 7.3 ° peak and the 9.4 ° peak has a maximum diffraction peak at the other 27.2 °. Compared with the crystal type, it has high chemical stability and good chargeability and soil resistance. Therefore, in the single-layer photoconductor of the present invention, the above-described crystal type further having a peak at 26.3 °, that is, a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542Å) of CuKα. ) Having a maximum diffraction peak at 27.2 °, and further having main peaks at 9.4 °, 9.6 °, and 24.0 °, and 7 as the lowest diffraction peak. A peak at 3 °, no peak between the peak at 7.3 ° and the peak at 9.4 °, a peak at 26.3 °, and a peak intensity of 26.3 ° By using titanyl phthalocyanine in the range of 1 to 99% with respect to the peak intensity of 27.2 °, the occurrence of soiling can be further reduced.

｛但し、上記一般式中、Ｒ１、Ｒ２は、それぞれ独立に水素原子、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表し、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０はそれぞれ独立に水素原子、ハロゲン原子、シアノ基、ニトロ基、アミノ基、水酸基、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表す。｝ That is, this invention consists of the following aspects.
(1) At least a photosensitive layer is provided on a conductive support, and the photosensitive layer is at least a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to characteristic X-rays (wavelength 1.542 mm) of CuKα as a charge generating material. ) Having a maximum diffraction peak at least 27.2 °, a further peak at 26.3 °, and a peak intensity of 26.3 ° is 1 to 99% of the peak intensity of 27.2 °. An electrophotographic photosensitive member comprising a single layer containing a range of titanyl phthalocyanine as an electron transport material represented by the following general formula (1) as a charge transport material.

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

(2) The titanyl phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα characteristic X-ray (wavelength 1.542 mm); It has major peaks at 4 °, 9.6 ° and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, a peak at 7.3 ° and 9.4 °. Titanyl phthalocyanine having no peak between 26.3 ° and a peak at 26.3 ° with a peak intensity at 26.3 ° in the range of 1 to 99% with respect to a peak intensity of 27.2 ° The electrophotographic photosensitive member according to (1), wherein

(3) The electrophotographic photosensitive member according to claim 1 or 2, wherein the peak intensity at 26.3 ° is 9 to 24% with respect to the peak intensity at 27.2 °.
(4) An image forming apparatus comprising the electrophotographic photosensitive member according to any one of (1) to (3).

(5) A process cartridge in which at least the electrophotographic photosensitive member according to any one of (1) to (3) is detachable from an image forming apparatus .

(6) An image forming apparatus comprising the process cartridge according to (5).
(7) A full-color image forming apparatus comprising the process cartridge according to (5).

  According to the present invention, there is provided a single-layer photoconductor that does not produce an abnormal image such as a background stain even when used repeatedly with high sensitivity. Also, by using this, an image forming apparatus and a full-color image forming apparatus that can perform high-quality image formation over a long period of time are provided. In addition, a process cartridge with high convenience in handling is provided.

The electrophotographic photoreceptor of the present invention will be described in detail below with reference to the drawings.
FIG. 7 is a cross-sectional view schematically showing an example of an electrophotographic photosensitive member having the layer structure of the present invention, in which a photosensitive layer (22) is provided on a conductive support (21).
Examples of the conductive support (21) include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, iron, tin oxide, An oxide such as indium oxide coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc., and drawing ironing method or impact ironing method It is possible to use pipes that have been surface-treated by cutting, superfinishing, polishing, etc. after being made into raw pipes by methods such as the Extruded Ironing method, Extruded Drawing method, and cutting method.

  The photosensitive layer (22) in the present invention has a maximum diffraction of at least 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to a characteristic X-ray (wavelength 1.542 mm) of CuKα as a charge generating material. A titanyl phthalocyanine having a peak, further having a peak at 26.3 °, and a peak intensity at 26.3 ° in the range of 1 to 99% with respect to a peak intensity of 27.2 °, generally used as a charge transport material It consists of a single layer containing the electron transport material represented by Formula (1).

First, the charge generation material in the present invention will be described.
The titanyl phthalocyanine in the present invention is a titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542Å) of known CuKα. It can be obtained by crystal conversion. A titanyl phthalocyanine having a maximum diffraction peak at least 27.2 ° can be obtained by known synthesis methods described in JP-A Nos. 2001-19871, 11-5919, and 3-269064.

There are two types of specific methods for crystal conversion.
One is a method of treating titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° in an organic solvent. Any organic solvent can be used as long as it can convert the crystal form having the maximum diffraction peak at 27.2 ° to the crystal form having the maximum diffraction peak at 26.3 °. Aromatic hydrocarbons such as acetone, ketones such as acetone and 2-butanone, halogenated hydrocarbons such as methylene chloride and chloroform, and cyclic ethers such as tetrahydrofuran are preferably used.
Regarding the treatment of the organic solvent, the titanyl phthalocyanine may be simply immersed in the organic solvent as it is, but the treatment time can be shortened by using auxiliary means such as stirring and ultrasonic application, It is valid. After the treatment with an organic solvent, the target titanyl phthalocyanine can be obtained by filtering and separating and drying.

  As another method, crystal transformation is performed by applying mechanical shearing force to titanyl phthalocyanine having a maximum diffraction peak at 27.2 °. At this time, an organic solvent may be used in combination, but it is desirable to perform the treatment in a dry state without using it together. As a method to be used, dry milling using a ball mill, attritor, vibration mill, kneader, or the like, or simply dry milling using a mixer is also effective. Moreover, you may use inorganic salts, such as salt, as an adjuvant in the case of dry milling. When an auxiliary agent is used, a washing step for removing the inorganic salt is necessary after the crystal conversion treatment.

The target titanyl phthalocyanine can be obtained as described above.
Whichever method is used, it is important that the peak intensity at 26.3 ° is in the range of 1 to 99% with respect to the peak intensity at the maximum diffraction peak of 27.2 °. The peak intensity of 26.3 ° is determined by the processing time in the solvent or the processing time for applying the mechanical shearing force, but it depends on the state of titanyl phthalocyanine used (for example, the size and hardness of the powder). Therefore, it is desirable to determine the processing time by preliminary experiments.

  As will be described later, when preparing the photosensitive layer coating solution, the charge generation material is previously used, if necessary, together with a binder resin, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, ball mill, attritor, sand mill, etc. It is preferable to prepare a dispersion liquid dispersed by the above. Therefore, the above crystal conversion can be performed simultaneously with the preparation of the charge generation material dispersion.

Next, the peak intensity of the 26.3 ° peak intensity of the titanyl phthalocyanine in the present invention relative to the 27.2 ° peak intensity will be described.
An X-ray diffraction spectrum is measured with a general X-ray diffractometer in a powder state of titanyl phthalocyanine to be used. Baseline correction is performed on the obtained spectrum, and then a peak intensity of 26.3 ° ± 0.2 ° and a peak intensity of 27.2 ° ± 0.2 ° are obtained. Using this value, the value obtained by dividing the peak intensity of 26.3 ° ± 0.2 ° by the peak intensity of 27.2 ° ± 0.2 ° is the peak intensity ratio in the present invention.
Peak intensity ratio (%)
= 26.3 ° ± 0.2 ° peak intensity / 27.2 ° ± 0.2 ° peak intensity When the peak intensity ratio is as small as several percent, the baseline correction is required for a wide range of measurements. May be difficult. In that case, the intensity ratio can be obtained more accurately by narrowing the measurement range (for example, measuring in a range of 20 to 30 °) and performing re-measurement.

｛但し、上記一般式中、Ｒ１、Ｒ２は、それぞれ独立に水素原子、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表し、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０はそれぞれ独立に水素原子、ハロゲン原子、シアノ基、ニトロ基、アミノ基、水酸基、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表す。｝ Next, the charge transport material will be described.
The electron transport material represented by the general formula (1) used in the present invention has a structural skeleton shown below.

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

  The substituted or unsubstituted alkyl group is an alkyl group having 1 to 25 carbon atoms, preferably 1 to 10 carbon atoms, specifically a methyl group, an ethyl group, an n-propyl group, an n- Straight chain such as butyl group, n-pentyl group, n-hexyl group, n-peptyl group, n-octyl group, n-nonyl group, n-decyl group, i-propyl group, s-butyl group, t -Branched group such as butyl group, methylpropyl group, dimethylpropyl group, ethylpropyl group, diethylpropyl group, methylbutyl group, dimethylbutyl group, methylpentyl group, dimethylpentyl group, methylhexyl group, dimethylhexyl group, alkoxy Alkyl group, monoalkylaminoalkyl group, dialkylaminoalkyl group, halogen-substituted alkyl group, alkylcarbonylalkyl group, Kishiarukiru group, alkanoyloxy group, an aminoalkyl group, esterified optionally alkyl group substituted with a carboxyl group which have an alkyl group substituted by a cyano group are exemplified. The substitution position of these substituents is not particularly limited, and a group in which a part of carbon atoms of the substituted or unsubstituted alkyl group is substituted with a hetero atom (N, O, S, etc.) is also substituted. Included in the alkyl group.

  The substituted or unsubstituted cycloalkyl group includes a cycloalkyl ring having 3 to 25 carbon atoms, preferably 3 to 10 carbon atoms, specifically, a homocyclic ring from cyclopropane to cyclodecane, methylcyclo Those having an alkyl substituent such as pentane, dimethylcyclopentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, tetramethylcyclohexane, ethylcyclohexane, diethylcyclohexane, t-butylcyclohexane, alkoxyalkyl groups, monoalkylaminoalkyl groups, dialkylamino Alkyl group, halogen-substituted alkyl group, alkoxycarbonylalkyl group, carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, halogen atom, amino group, esterified Which may be a carboxyl group, a cycloalkyl group substituted by a cyano group and the like. The substitution position of these substituents is not particularly limited, and a group in which a part of carbon atoms of the substituted or unsubstituted cycloalkyl group is substituted with a hetero atom (N, O, S, etc.) is also substituted. It is included in the cycloalkyl group.

Examples of the substituted or unsubstituted aralkyl group include groups in which an aromatic ring is substituted on the above-described substituted or unsubstituted alkyl group, and an aralkyl group having 6 to 14 carbon atoms is preferable. More specifically, benzyl group, perfluorophenylethyl group, 1-phenylethyl group, 2-phenylethyl group, terphenylethyl group, dimethylphenylethyl group, diethylphenylethyl group, t-butylphenylethyl group, 3- Examples thereof include a phenylpropyl group, a 4-phenylbutyl group, a 5-phenylpentyl group, a 6-phenylhexyl group, a benzhydryl group, and a trityl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

More specifically, an electron transport material represented by the following structural formulas (1) to (7) is preferable in that the obtained image has high quality. In the formula, Me represents a methyl group.

式中、ＲｎはＲ３、Ｒ４、Ｒ７、Ｒ８を表し、ＲｍはＲ５、Ｒ６、Ｒ９、Ｒ１０を表す。 Examples of the method for producing the electron transport material represented by the general formula (1) include the following methods.
Naphthalenecarboxylic acid is synthesized from the following reaction formula according to a known synthesis method (for example, US Pat. No. 6,794,102, Industrial Organic Pigments 2nd edition, VCH, 485 (1997)).

In the formula, Rn represents R3, R4, R7, R8, and Rm represents R5, R6, R9, R10.

  The electron transport material represented by the general formula (1) used in the present invention is a method of reacting the above naphthalenecarboxylic acid or its anhydride with amines to monoimidize, or using a buffer solution for naphthalenecarboxylic acid or its anhydride. It is obtained by a method of adjusting pH and reacting with diamines. Monoimidization is carried out without solvent or in the presence of a solvent. The solvent is not particularly limited, but it does not react with raw materials or products such as benzene, toluene, xylene, chloronaphthalene, acetic acid, pyridine, methylpyridine, dimethylformamide, dimethylacetamide, dimethylethyleneurea, dimethylsulfoxide, and the like. It is good to use what can be made to react at the temperature of -250 degreeC. For pH adjustment, a buffer solution prepared by mixing a basic aqueous solution such as lithium hydroxide or potassium hydroxide with an acid such as phosphoric acid is used. Carboxylic acid derivative dehydration reaction obtained by reacting carboxylic acid with amines or diamines is carried out in the absence of a solvent or in the presence of a solvent. Although there is no restriction | limiting in particular as a solvent, It is good to use what reacts at the temperature of 50 to 250 degreeC, without reacting with raw materials and products, such as benzene, toluene, chloronaphthalene, bromonaphthalene, and acetic anhydride. Any reaction may be carried out without a catalyst or in the presence of a catalyst, and is not particularly limited. For example, molecular sieves, benzenesulfonic acid, p-toluenesulfonic acid and the like can be used as a dehydrating agent.

  The charge transport material includes an electron transport material that transports electrons and a hole transport material that transports holes, and the photoreceptor used in the present invention includes an electron transport material and a hole transport material as charge transport materials. It is preferable to include both.

In the present invention, it is essential to include the electron transport material represented by the general formula (1), but in addition to this, a known charge transport material, that is, an electron transport material or a hole transport material may be used in combination.
Examples of the electron transport material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide.
These electron transport materials may be used alone or as a mixture of two or more.

As the hole transport material, an electron donating substance is preferably used.
Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, Examples include styrylpyrazolines, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, and thiophene derivatives.
These hole transport materials may be used alone or as a mixture of two or more.

Known polymer compounds can be used as the polymer compound that can be used as the binder component of the photosensitive layer. For example, polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, Thermoplastic such as polyarylate resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin Although thermosetting resin is mentioned, it is not limited to these.
Among these polymer compounds, polycarbonate resin is particularly preferable from the viewpoint of film quality.

  As a method for forming the photosensitive layer, a casting method from a solution dispersion system is preferable. In order to provide a photosensitive layer by the casting method, a coating solution prepared by dispersing or dissolving a charge generating material, a charge transporting material, a binder resin, and, if necessary, other components in an appropriate solvent is adjusted to an appropriate concentration. Adjust and apply.

In order to uniformly disperse the charge generation material in the photosensitive layer (in the coating solution), the charge generation material is previously ball milled with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, It is preferable to prepare a dispersion liquid dispersed by an attritor, a sand mill or the like.
Application can be performed by dip coating, spray coating, bead coating, or the like.

  Examples of the dispersion solvent that can be used in preparing the photosensitive layer coating solution provided as described above include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, and ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve. And aromatics such as toluene and xylene, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate. These solvents can be used alone or in combination.

  In the photosensitive layer, the charge generating material is 0.1 to 30% by weight, preferably 0.5 to 10% by weight, based on the entire photosensitive layer. The electron transport material is suitably 5 to 300 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the binder resin component. However, the electron transport material represented by the general formula (1) is preferably 50 to 100% by weight with respect to the entire electron transport material. The hole transport material is suitably 5 to 300 parts by weight, preferably 20 to 150 parts by weight with respect to 100 parts by weight of the binder resin component. When the electron transport material and the hole transport material are used in combination, the total amount of the electron transport material and the hole transport material is 20 to 300 parts by weight, preferably 30 to 200 parts by weight with respect to 100 parts by weight of the binder resin component. It is.

Further, if necessary, low-molecular compounds such as antioxidants, plasticizers, lubricants and ultraviolet absorbers and leveling agents can be added to the photosensitive layer. These compounds can be used alone or as a mixture of two or more. The amount of the low molecular compound used is 0.1 to 50 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the binder resin, and the amount of leveling agent used is 100 parts by weight of the binder resin. About 0.001 to 5 parts by weight is appropriate.
The film thickness of the photosensitive layer is suitably about 5 to 40 μm, preferably about 15 to 35 μm.

As shown in FIG. 8, the electrophotographic photosensitive member used in the present invention may be provided with an undercoat layer (23) between the conductive support (21) and the photosensitive layer (22). The undercoat layer is provided for the purpose of improving adhesiveness, improving the coatability of the upper layer, reducing the residual potential, and preventing charge injection from the conductive support.
In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is applied on the resin using a solvent, the resin is a resin having high resistance to general organic solvents. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.

In addition, a fine powder such as a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, or indium oxide, or a metal sulfide or metal nitride may be added to the undercoat layer. These undercoat layers can be formed using an appropriate solvent and coating method, as in the case of the above-described photosensitive layer.
Further, as the undercoat layer, a metal oxide layer formed by using, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful. In addition to this, alumina is provided by anodic oxidation, organic materials such as polyparaxylylene (parylene), and inorganic materials such as silicon oxide, tin oxide, titanium oxide, ITO, ceria are provided by the vacuum thin film manufacturing method. It can be used well as an undercoat layer.
The thickness of the undercoat layer is suitably from 0.1 to 10 μm, more preferably from 1 to 5 μm.

  In the present invention, an antioxidant, a plasticizer, an ultraviolet absorber, and a leveling agent can be added to the photosensitive layer in order to improve gas barrier properties and environmental resistance.

Next, the image forming apparatus of the present invention will be described.
FIG. 1 is a schematic view for explaining an image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 1, a photoreceptor (11) is a photoreceptor that satisfies the requirements of the present invention. Although the photoconductor (11) has a drum shape, it may have a sheet shape or an endless belt shape.
As the charging means (12), known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. The charging means (12) is preferably used in contact with or in close proximity to the photoreceptor from the viewpoint of reducing power consumption. In particular, in order to prevent contamination of the charging means (12), a charging mechanism disposed in the vicinity of the photoreceptor having an appropriate gap between the photoreceptor and the surface of the charging means is desirable.
In the present invention, either positive or negative can be used as the polarity of the charge. However, the positive charge is more preferable than the negative charge because the chargeability is stable and the amount of ozone generated is small.

As the transfer means (16), the above charger can be generally used, but a combination of a transfer charger and a separation charger is effective.
The light source used for the exposure means (13), the charge removal means (1A), etc. includes fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LDs), electroluminescence ( EL) in general. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  The toner (15) developed on the photoreceptor by the developing means (14) is transferred to the image receiving medium (18), but not all is transferred, and toner remaining on the photoreceptor is also generated. Such toner is removed from the photoreceptor by the cleaning means (17). As the cleaning means, a rubber cleaning blade, a brush such as a fur brush, a mag fur brush, or the like can be used.

FIG. 2 shows another example of an electrophotographic process according to the present invention. In FIG. 2, the photoconductor (11) satisfies the requirements of the present invention and has an endless belt shape.
Driven by drive means (1C), charged by charging means (12), image exposure by exposure means (13), development (not shown), transfer by transfer means (16), cleaning by pre-cleaning exposure means (1B). Pre-exposure, cleaning by the cleaning means (17), and static elimination by the static elimination means (1A) are repeated. In FIG. 2, light irradiation for pre-cleaning exposure is performed from the support side of the photoreceptor (in this case, the support is translucent).
The above electrophotographic process exemplifies an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 2, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or image exposure and neutralization light irradiation may be performed from the support side. On the other hand, in the light irradiation process, image exposure, pre-cleaning exposure, and static elimination exposure are illustrated. In addition, pre-exposure exposure, pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.

  Further, the image forming means as described above may be fixedly incorporated in a copying machine, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. Also in this case, the photoreceptor (11) is a photoreceptor that satisfies the requirements of the present invention. Although the photoconductor (11) has a drum shape, it may have a sheet shape or an endless belt shape.

  FIG. 4 shows an example of a full-color image forming apparatus according to the present invention. In this electrophotographic apparatus, charging means (charging device) (12), exposure means (13), black (Bk), cyan (C), magenta (M), and yellow (Y) are disposed around the photoreceptor (11). Developing means (14Bk, 14C, 14M, 14Y) for each color toner, an intermediate transfer belt (1F) as an intermediate transfer member, and a cleaning means (17) are arranged in this order. Here, the subscripts Bk, C, M, and Y shown in the figure correspond to the color of the toner, and are added or omitted as appropriate.

  The photoreceptor (11) is an electrophotographic photoreceptor that satisfies the requirements of the present invention. Each color developing means (14Bk, 14C, 14M, 14Y) can be controlled independently, and only the color developing means for image formation is driven. The toner image formed on the photoreceptor (11) is transferred onto the intermediate transfer belt (1F) by the first transfer means (1D) disposed inside the intermediate transfer belt (1F). The first transfer means (1D) is arranged so as to be able to come into contact with and separate from the photoreceptor (11), and the intermediate transfer belt (1F) is brought into contact with the photoreceptor (11) only during the transfer operation. The respective color images are sequentially formed, and the toner images superimposed on the intermediate transfer belt (1F) are collectively transferred to the image receiving medium (18) by the second transfer means (1E) and then fixed by the fixing means (19). The image is formed by fixing. The second transfer means (1E) is also arranged so as to be able to contact and separate from the intermediate transfer belt (1F), and abuts on the intermediate transfer belt (1F) only during the transfer operation.

  In the transfer drum type electrophotographic apparatus, since the toner images of the respective colors are sequentially transferred onto the transfer material electrostatically attracted to the transfer drum, there is a limitation on the transfer material that cannot be printed on cardboard, as shown in FIG. Such an intermediate transfer type electrophotographic apparatus has an advantage that the toner images of the respective colors are superimposed on the intermediate transfer body (1F), and thus are not limited by the transfer material. Such an intermediate transfer method is not limited to the apparatus shown in FIG. 4, but can be applied to the electrophotographic apparatus shown in FIGS. 1, 2, and 3 and FIG. 5 (a specific example is shown in FIG. 6) described later. it can.

  FIG. 5 shows another example of a full-color image forming apparatus according to the present invention. This image forming apparatus is of a type using four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) as toner, and an image forming unit is provided for each color. In addition, photoconductors (11Y, 11M, 11C, 11Bk) for each color are provided. The photoreceptor used in this electrophotographic apparatus is a photoreceptor that satisfies the requirements of the present invention. Around each photoconductor (11Y, 11M, 11C, 11Bk), charging means (12Y, 12M, 12C, 12Bk), exposure means (13Y, 13M, 13C, 13Bk), developing means (14Y, 14M, 14C, 14Bk), cleaning means (17Y, 17M, 17C, 17Bk) and the like are provided. Further, a transfer transfer belt (1G) as a transfer material carrier that comes in contact with and separates from each transfer position of each photoconductor (11Y, 11M, 11C, 11Bk) arranged on a straight line is hung by a driving means (1C). Has been passed. Transfer means (16Y, 16M, 16C, 16Bk) are disposed at transfer positions facing the respective photoconductors (11Y, 11M, 11C, 11Bk) with the conveyance transfer belt (1G) interposed therebetween.

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

Hereinafter, the present invention will be described by way of examples. Note that this does not limit the scope of the present invention. All parts are parts by weight.
First, a synthesis example of the electron transport material used in this embodiment will be described.

Electron transport material synthesis example 1
First Step In a 200 ml four-necked flask, 5.0 g (18.6 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 2.14 g (18.6 mmol) of 2-aminoheptane and 25 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / hexane to obtain 2.14 g of monoimide A (yield 31.5%).
Second Step In a 100 ml four-necked flask, 2.0 g (5.47 mmol) of monoimide A, 0.137 g (2.73 mmol) of hydrazine monohydrate, 10 mg of p-toluenesulfonic acid, and 50 ml of toluene are placed for 5 hours. Heated to reflux. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized with toluene / ethyl acetate to obtain 0.668 g (yield 33.7%) of the electron transport material represented by the structural formula (1). (Referred to as electron transport material 1)
In mass spectrometry (FD-MS), a peak of M / z = 726 was observed and identified as a target product. In the elemental analysis, calculated values were 69.41% carbon, 5.27% hydrogen, and 7.71% nitrogen, and the measured values were 69.52% carbon, 5.09% hydrogen, and 7.93% nitrogen.

Electron transport material synthesis example 2
First Step In a 200 ml four-necked flask, 10 g (37.3 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 0.931 g (18.6 mmol) of hydrazine monohydrate, p-toluenesulfonic acid 20 mg and 100 ml of toluene were added and heated to reflux for 5 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. The recovered product was recrystallized from toluene / ethyl acetate to obtain 2.84 g of dimer C (yield 28.7%).
Second Step In a 100 ml four-necked flask, 2.5 g (4.67 mmol) of dimer C and 30 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminopropane 0.278 g (4.67 mmol) and DMF 10 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue and the residue was purified by silica gel column chromatography to obtain 0.556 g of monoimide C (yield 38.5%).
Third Step In a 50 ml four-necked flask, 0.50 g (1.62 mmol) of monoimide C and 10 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminoheptane 0.186 g (1.62 mmol) and DMF 5 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / hexane to obtain 0.243 g (yield 22.4%) of the electron transport material represented by the structural formula (2). (Referred to as electron transport material 2)
In mass spectrometry (FD-MS), the peak was identified as M / z = 670, and the product was identified as the target product. In the elemental analysis, the calculated values were 68.05% carbon, 4.51% hydrogen, and 8.35% nitrogen, and the measured values were 68.29% carbon, 4.72% hydrogen, and 8.33% nitrogen.

Electron transport material synthesis example 3
First Step In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of the above-mentioned dimer C and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 1.08 g (9.39 mmol) DMF 25 ml of 2-aminoheptane was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography to obtain 1.66 g (yield 28.1%) of monoimide D.
Second Step In a 100 ml four-necked flask, 1.5 g (2.38 mmol) of monoimide D and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminooctane 0.308 g (2.38 mmol) and DMF 10 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / hexane to obtain 0.328 g (yield 18.6%) of an electron transport material represented by the structural formula (4). (Referred to as electron transport material 3)

Next, a synthesis example of a charge generation material (titanyl phthalocyanine) will be described.
(Comparative Synthesis Example 1)
A pigment was prepared according to Japanese Patent Application Laid-Open No. 2001-19871. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained. Dissolve the crude titanyl phthalocyanine in 20 times the amount of concentrated sulfuric acid, add dropwise to 100 times the amount of ice water with stirring, filter the precipitated crystals, and then repeat washing with water until the washing solution becomes neutral. (Water paste) was obtained. 2 g of the obtained wet cake (water paste) was added to 20 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder (referred to as titanyl phthalocyanine 1).

The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions, and as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to Cu-Kα rays (wavelength 1.542 mm) described in the publication, It has a maximum diffraction peak at least 27.2 °, and further main peaks at 9.4 °, 9.6 ° and 24.0 °, and the lowest diffraction peak at 7.3 °. It was confirmed that it was a titanyl phthalocyanine having a peak and having no peak between the peak at 7.3 ° and the peak at 9.4 °. The obtained titanyl phthalocyanine did not have a peak at 26.3 °.
An X-ray diffraction spectrum is shown in FIG.
(X-ray diffraction spectrum measurement conditions)
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

(Comparative Synthesis Example 2)
30 g of titanyl phthalocyanine obtained in Comparative Synthesis Example 1 was immersed in 300 g of tetrahydrofuran to perform crystal conversion. After being left immersed for 2 hours, it was filtered and dried to obtain titanyl phthalocyanine powder (referred to as titanyl phthalocyanine 2).

(Synthesis Example 1)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 4 hours (referred to as titanyl phthalocyanine 3).
(Synthesis Example 2)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 10 hours (referred to as titanyl phthalocyanine 4).
(Synthesis Example 3)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 15 hours (referred to as titanyl phthalocyanine 5).

(Synthesis Example 4)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 24 hours (referred to as titanyl phthalocyanine 6).
(Synthesis Example 5)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 36 hours (referred to as titanyl phthalocyanine 7).
(Synthesis Example 6)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 48 hours (referred to as titanyl phthalocyanine 8).

(Comparative Synthesis Example 3)
A titanyl phthalocyanine powder was obtained in the same manner as Comparative Synthesis Example 2 except that the crystal conversion time was changed to 60 hours (referred to as titanyl phthalocyanine 9).
(Comparative Synthesis Example 4)
A titanyl phthalocyanine powder was obtained in the same manner as in Comparative Synthesis Example 2 except that the crystal conversion time was changed to 72 hours (referred to as titanyl phthalocyanine 10).

(Comparative Synthesis Example 5)
According to the method described in Preparation Example 1 of JP-A-3-269064 (Patent No. 2854682), titanyl phthalocyanine was prepared. That is, the wet cake prepared in Comparative Synthesis Example 1 was dried, and 1 g of the dried product was stirred (50 ° C.) in a mixed solvent of 10 g of ion-exchanged water and 1 g of monochlorobenzene for 1 hour, and then methanol and ion-exchanged water. Washed and dried to obtain titanyl phthalocyanine powder (referred to as titanyl phthalocyanine 11).
The titanyl phthalocyanine 11 obtained as described above was measured for an X-ray diffraction spectrum under the conditions of Comparative Synthesis Example 1 and confirmed to be the same as the spectrum described in the publication. It had a maximum diffraction peak at 27.2 ° and no peak at 26.3 °.

(Synthesis Example 7)
30 g of titanyl phthalocyanine obtained in Comparative Synthesis Example 5 was immersed in 300 g of tetrahydrofuran to perform crystal conversion. After being left immersed for 10 hours, it was filtered and dried to obtain titanyl phthalocyanine powder (referred to as titanyl phthalocyanine 12).
(Synthesis Example 8)
A titanyl phthalocyanine powder was obtained in the same manner as in Synthesis Example 7 except that the crystal conversion time was changed to 30 hours (referred to as titanyl phthalocyanine 13).
(Synthesis Example 9)
A titanyl phthalocyanine powder was obtained in the same manner as in Synthesis Example 7 except that the crystal conversion time was changed to 40 hours (referred to as titanyl phthalocyanine 14).

(Comparative Synthesis Example 6)
A titanyl phthalocyanine powder was obtained in the same manner as in Synthesis Example 7 except that the crystal conversion time was changed to 50 hours (referred to as titanyl phthalocyanine 15).
(Comparative Synthesis Example 7)
A titanyl phthalocyanine powder was obtained in the same manner as in Synthesis Example 7 except that the crystal conversion time was changed to 60 hours (referred to as titanyl phthalocyanine 16).

  With respect to the titanyl phthalocyanines 2 to 10 and 12 to 16 obtained in the above Comparative Synthesis Examples 2 to 4, 6, 7, and Synthesis Examples 1 to 9, X-ray diffraction spectra were measured under the conditions of Comparative Synthesis Example 1. As a representative example of the obtained X-ray diffraction spectrum diagram, an X-ray diffraction spectrum diagram of titanyl phthalocyanine obtained in Synthesis Example 3 is shown in FIG. 10 (the arrow in the figure is a peak at 26.3 °, and the peak intensity ratio) Is 9%). Further, peak intensity ratios of 26.3 ° and 27.2 ° were obtained from the respective X-ray diffraction spectra. The results are shown in Table 1.

こうして得られた感光層用塗工液をφ３０ｍｍ、長さ３４０ｍｍアルミニウムドラム上に、浸漬塗工法にて塗布、１２０℃で２０分間乾燥し、２５μｍの感光層を形成し、感光体を得た（感光体１とする）。 (Comparative Example 1)
The titanyl phthalocyanine 1 prepared in Comparative Synthesis Example 1 was dispersed under the following composition and conditions to prepare a pigment dispersion.
Titanyl phthalocyanine 1 3 parts Cyclohexanone 97 parts A φ2 cm PSZ ball was placed in a φ9 cm glass pot and dispersed for 1 hour at a rotation speed of 100 rpm.
A photoconductor coating solution having the following composition was prepared using the dispersion.
60 parts of the dispersion liquid hole transport material of the following structural formula (8) 30 parts electron transport material 1 20 parts Z type polycarbonate resin 50 parts (Teijin Chemicals: Panlite TS-2050)
0.01 parts of silicone oil (Shin-Etsu Chemical Co., Ltd .: KF50)
Tetrahydrofuran 350 parts

The photosensitive layer coating solution thus obtained was applied on an aluminum drum having a diameter of 30 mm and a length of 340 mm by a dip coating method and dried at 120 ° C. for 20 minutes to form a photosensitive layer having a thickness of 25 μm. Photoconductor 1).

(Examples 1-6, Comparative Examples 2-4)
In Comparative Example 1, photoconductors were obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 2 to 10 (corresponding to the numbers of titanyl phthalocyanine, respectively, photoconductors 2 to 10 were obtained). ).

(Comparative Example 5)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that the electron transport material 1 was changed to the electron transport material 2 in Comparative Example 1 (referred to as Photoreceptor 11).

(Example 7)
A photoconductor was obtained in the same manner as in Comparative Example 5 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 5 in Comparative Example 5 (referred to as Photoconductor 12).
(Example 8)
A photoconductor was obtained in the same manner as in Comparative Example 5 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 7 in comparative example 5 (referred to as photoconductor 13).
Example 9
A photoconductor was obtained in the same manner as in Comparative Example 5 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 8 in Comparative Example 5 (referred to as Photoconductor 14).

(Comparative Example 6)
A photoconductor was obtained in the same manner as in Comparative Example 5 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 9 in Comparative Example 5 (referred to as Photoconductor 15).
(Comparative Example 7)
A photoconductor was obtained in the same manner as in Comparative Example 5 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 10 in comparative example 5 (referred to as photoconductor 16).

(Comparative Example 8)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that the electron transport material 1 was changed to the electron transport material 3 in Comparative Example 1 (referred to as Photoconductor 17).
(Example 10)
A photoreceptor was obtained in the same manner as in Comparative Example 8 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 6 in Comparative Example 8 (referred to as Photoreceptor 18).
(Example 11)
A photoreceptor was obtained in the same manner as in Comparative Example 8 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 7 in Comparative Example 8 (referred to as Photoreceptor 19).
(Example 12)
A photoconductor was obtained in the same manner as in Comparative Example 8 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 8 in comparative example 8 (referred to as photoconductor 20).

(Comparative Example 9)
A photoconductor was obtained in the same manner as in Comparative Example 8 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 9 in Comparative Example 8 (referred to as Photoconductor 21).
(Comparative Example 10)
A photoconductor was obtained in the same manner as in Comparative Example 8 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 10 in Comparative Example 8 (referred to as Photoconductor 22).

(Comparative Example 11)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 11 in Comparative Example 1 (referred to as Photoconductor 23).
(Example 13)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 12 in Comparative Example 1 (referred to as Photoconductor 24).
(Example 14)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 13 in Comparative Example 1 (referred to as Photoconductor 25).
(Example 15)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 14 in Comparative Example 1 (referred to as Photoconductor 26).

(Comparative Example 12)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 15 in Comparative Example 1 (referred to as Photoconductor 27).
(Comparative Example 13)
A photoconductor was obtained in the same manner as in Comparative Example 1 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 16 in Comparative Example 1 (referred to as Photoconductor 28).

(Comparative Example 14)
In Comparative Example 1, a photoconductor was obtained in the same manner as in Comparative Example 1 except that the electron transport material 1 was changed to an electron transport material of the following structural formula (9) (referred to as an electron transport material 4). To do).

(Comparative Example 15)
A photoconductor was obtained in the same manner as in Comparative Example 14 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 5 in Comparative Example 14 (referred to as Photoconductor 30).
(Comparative Example 16)
A photoreceptor was obtained in the same manner as in Comparative Example 14 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 7 in Comparative Example 14 (referred to as Photoreceptor 31).
(Comparative Example 17)
A photoreceptor was obtained in the same manner as in Comparative Example 14 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 8 in Comparative Example 14 (referred to as Photoreceptor 32).

(Comparative Example 18)
A photoreceptor was obtained in the same manner as in Comparative Example 14 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 9 in Comparative Example 14 (referred to as Photoreceptor 33).
(Comparative Example 19)
A photoreceptor was obtained in the same manner as in Comparative Example 14 except that titanyl phthalocyanine 1 was changed to titanyl phthalocyanine 10 in Comparative Example 14 (referred to as Photoreceptor 34).

Photoconductor Evaluation The sensitivity of the photoconductors 1 to 34 produced as described above was evaluated as follows using an electrostatic property test apparatus (manufactured by Ricoh). First, corona discharge was performed at a discharge voltage of +5.2 kV, positively charged, and then dark decayed. Subsequently, when the surface potential becomes +800 V, the monochromatic light of 780 nm is irradiated with 10 μW / cm ^2, and the exposure amount E1 / 10 (μJ / cm ² ) necessary for optical attenuation of the surface potential to +80 V is measured. did. FIG. 11 shows a series of evaluation results according to the electron transport material used for the photoreceptor and the type of titanyl phthalocyanine (titanyl phthalocyanine 1 or 11) before crystal conversion.
Series 1: titanyl phthalocyanine 1 + electron transport material 1 (photoconductors 1 to 10)
Series 2: titanyl phthalocyanine 1 + electron transport material 2 (photosensitive members 11 to 16)
Series 3: titanyl phthalocyanine 1 + electron transport material 3 (photosensitive members 17 to 22)
Series 4: titanyl phthalocyanine 11 + electron transporting material 1 (photoconductors 23 to 28)
Series 5: titanyl phthalocyanine 1 + electron transport material 4 (photosensitive members 29 to 34)

  As can be seen from the evaluation results, a titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα and a general formula In the case of the single-layer photoreceptor using the electron transport material represented by (1) (series 1 to 4), the sensitivity is almost lowered until the peak intensity ratio of 26.3 ° is about 100%. High sensitivity is maintained. It can also be seen that when the peak intensity ratio at 26.3 ° exceeds 100%, the sensitivity decreases rapidly. On the other hand, in the series 5 which is not the electron transport material represented by the general formula (1), the sensitivity decreases with an increase in the peak intensity ratio of 26.3 °, and the electron transport material represented by the general formula (1). It can be seen that the sensitivity is lower than that when using.

(Examples 16-22 and Comparative Examples 20-22)
After the photoreceptors 1 to 6 and the photoreceptors 23 to 26 are mounted, they are mounted on an electrophotographic apparatus (Imagio Neo 270 remodeled machine manufactured by Ricoh, a apparatus remodeled so as to be positively charged by replacing the power pack), and the writing rate Using a 5% chart (characters equivalent to 5% as an image area are written on the entire A4 surface), a printing durability test was performed to print 50,000 sheets in total.
The toner and developer used were exchanged for toner and developer having polarity reversed from those dedicated to imagio Neo 270.
The charging means of the electrophotographic apparatus used an external power source, and the voltage applied to the charging roller was an AC component with a peak-to-peak voltage of 1.9 kV and a frequency of 1.35 kHz. For the DC component, a bias was set so that the charging potential of the photosensitive member at the start of the test was +600 V, and the test was performed under this charging condition until the end of the test. The developing bias was + 450V. The test environment is 23 ° C. and 55% RH.

The background stain was evaluated before and after the printing durability test.
Dirt evaluation:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background. The evaluation ranks are as follows: ◎: Very good ○: Good △: Somewhat inferior ×: Very bad The evaluation results of Examples 16 to 22 and Comparative Examples 20 to 22 are shown in Table 2.

(Examples 23 to 29 and Comparative Examples 23 to 25)
After mounting the photoconductors 1 to 6 and the photoconductors 23 to 26, a full-color electrophotographic apparatus having a tandem mechanism (Ricoh's IPSiO Color8100 remodeling machine, remodeling the power pack to be positively charged, and further writing 1) using a 5% writing rate chart (characters equivalent to 5% as the image area are written on the entire A4 surface). A press life test for printing 10,000 sheets was conducted.
The toner and developer used were changed from a dedicated one for IPSiO Color 8100 to a toner and developer having opposite polarity.
The charging means of the electrophotographic apparatus used an external power source, and the voltage applied to the charging roller was selected as an AC component with a peak-to-peak voltage of 1.9 kV and a frequency of 1.35 kHz. For the DC component, a bias was set so that the charged potential of the photosensitive member at the start of the test was +600 V, and the test was performed under this charging condition until the end of the test. The developing bias was + 450V. The test environment is 23 ° C. and 55% RH.

After the printing durability test, the background stain and color reproducibility were evaluated.
Dirt evaluation:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
Color reproducibility:
An ISO / JIS-SCID image N1 (portrait) was output and the color color reproducibility was evaluated.
In any case, the evaluation ranks are as follows: ◎: Very good ○: Good △: Slightly inferior ×: Very bad The results of Examples 23 to 29 and Comparative Examples 23 to 25 are shown in Table 3.

As can be seen from the results in Tables 2 and 3, in the examples satisfying the requirements of the present invention, it can be seen that the occurrence of background contamination is suppressed even by repeated use.
As is apparent from the above embodiments, according to the present invention, there is provided a single-layer photoconductor that does not cause abnormal images such as background stains even when used repeatedly with high sensitivity. Also, by using this, an image forming apparatus and a full-color image forming apparatus that can perform high-quality image formation over a long period of time are provided. In addition, a process cartridge with high convenience in handling is provided.

1 is a schematic cross-sectional view illustrating an example of an image forming apparatus according to the present invention. It is a schematic cross section which shows another example of the image forming apparatus which concerns on this invention. It is a schematic cross section showing an example of a process cartridge according to the present invention. 1 is a schematic cross-sectional view illustrating an example of a full-color image forming apparatus according to the present invention. It is a schematic cross section which shows another example of the full-color image forming apparatus which concerns on this invention. It is a schematic cross section which shows another example of the full-color image forming apparatus which concerns on this invention. It is sectional drawing which shows the example of the layer structure of the electrophotographic photoreceptor which concerns on this invention. It is sectional drawing which shows the example of another layer structure of the electrophotographic photoreceptor which concerns on this invention. 2 is an X-ray diffraction spectrum diagram of titanyl phthalocyanine obtained in Comparative Synthesis Example 1. FIG. 4 is an X-ray diffraction spectrum diagram of titanyl phthalocyanine obtained in Synthesis Example 3. FIG. It is a graph which shows evaluation of the sensitivity of the photoreceptors 1-34 produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electrophotographic photoreceptor 12 ... Charging means 13 ... Exposure means 14 ... Developing means 15 ... Toner 16 ... Transfer means 17 ... Cleaning means 18 ... Image receiving medium 19 ... Fixing means 1A ... Charging means 1B ... Pre-cleaning exposure means 1C ... Drive means 1D ... First transfer means 1E ... Second transfer means 1F ... Intermediate transfer member 1G ... Conveyance transfer belt 21 ... Conductive support 22 ... Photosensitive layer 23 ... Undercoat layer

Claims (7)

At least a photosensitive layer is provided on a conductive support, and the photosensitive layer has at least a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to a characteristic X-ray (wavelength 1.542 mm) of CuKα as a charge generating material. It has a maximum diffraction peak at least 27.2 °, a further peak at 26.3 °, and a peak intensity at 26.3 ° is in the range of 1 to 99% with respect to a peak intensity of 27.2 °. An electrophotographic photoreceptor comprising a single layer containing titanyl phthalocyanine as an electron transport material represented by the following general formula (1) as a charge transport material.

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }   The titanyl phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of CuKα (wavelength 1.542 mm), and further 9.4 °, It has major peaks at 9.6 ° and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, with 7.3 ° and 9.4 ° peaks. The titanyl phthalocyanine has no peak in between, a peak at 26.3 °, and a peak intensity at 26.3 ° in the range of 1 to 99% with respect to a peak intensity of 27.2 °. The electrophotographic photosensitive member according to claim 1. The electrophotographic photosensitive member according to claim 1 , wherein the peak intensity at 26.3 ° is 9 to 24% with respect to the peak intensity at 27.2 ° .
An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1 .
A process cartridge in which at least the electrophotographic photosensitive member according to claim 1 is detachable from an image forming apparatus .
  An image forming apparatus, wherein the process cartridge according to claim 5 is mounted.   A full-color image forming apparatus, wherein the process cartridge according to claim 5 is mounted.

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