JPH0943881A - Electrophotographic photoreceptor, electrophotographic device using the photoreceptor and device unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the photoreceptor having a stabilized electrical characteritic in repeated use by incorporating either the oxytitanium phthalocyanine having a strong peak at a specified angle of diffraction at least in CuKα characteristic X-ray diffraction or a specified azo pigment or both and a specified polycarbonate resin into a charge generating layer. SOLUTION: This electrophotographic photoreceptor has a photosensitive layer on a substrate. Either the oxytitanium phthalocyanine having a strong peak at the angle of diffraction 2θ±0.2 deg. equal to 9.0 deg., 14.2 deg., 23.9 deg. and 27.1 deg. at least in CuKα characteristic X-ray diffraction or an azo pigment of formula I or both and a polycarbonate resin having a repeating unit shown by formulas II and III are incorporated as a charge generating substance into the photosensitive layer. In the formulas, R1 to R4 are repeatedly hydrogen atom, halogen atom, 1-6C alkyls, etc., (a) to (d) are respectively an integer of 0 to 4, X is -CR5 R6 -, etc., where R5 and R6 are respectively hydrogen atom, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
In particular, the present invention relates to a highly sensitive electrophotographic photosensitive member having excellent durability and having little deterioration in image quality due to repeated use.

[0002]

2. Description of the Related Art Conventionally, inorganic photoconductive substances such as selenium, cadmium sulfide and zinc oxide have been used as photoconductive substances for electrophotographic photoreceptors. On the other hand, recently, a material using an organic photosensitive material, which has advantages of low cost, productivity, and no pollution, has begun to be used. Among them, the function-separated type photoconductor in which the charge generating substance and the charge transporting substance are used in combination can significantly improve the sensitivity which has been a defect of the photoconductor using the organic photoconductive substance. , Has been especially noticed.

However, when the high-sensitivity photoconductor using such an organic photoconductive substance is repeatedly applied to the steps of charging, exposure, development, transfer, so-called Carlson process, the surface potential is lowered and the sensitivity is changed. , Etc. may occur, resulting in a phenomenon of deterioration (deterioration) of image quality.

The cause of the deterioration or fatigue is not yet clear, and various factors have been considered.

Generally, when a photoconductor is used in a copying machine, charge and exposure are repeatedly performed, so that charges are accumulated in the photosensitive layer, resulting in a decrease in surface potential and an increase in residual potential. It is considered that the image quality is deteriorated when it is repeatedly used.

Conventionally, as a method for preventing the above-mentioned deterioration of the electrophotographic photosensitive layer, it has been proposed to add various antioxidants such as trialkylphenol derivatives and dilaurylthiopropionate during the charge transport. (For example, Japanese Patent Publication No. 50-33857, Japanese Patent Publication No. 51-34736.
Issue, JP-A-56-130759, JP-A-57-1
22444 report).

Further, JP-A-62-105151 and JP-A-4-51248 report that the prevention of deterioration by the above-mentioned antioxidant is achieved more effectively.

Further, in JP-A-5-80548 and JP-A-5-257297, there is proposed a photosensitive body which is sensitive and highly durable by using a novel polycarbonate resin, but it is put to practical use. In addition, it was necessary to stabilize the characteristics during repeated use.

[0009]

As described above, by selecting various materials for the photosensitive layer, the deterioration of the photoconductor can be prevented to some extent, but it is necessary to further improve the prevention effect for practical use.

An object of the present invention is to provide an electrophotographic photosensitive member having stable electric characteristics upon repeated use.

Another object of the present invention is to provide an electrophotographic photosensitive member having sufficient sensitivity to a relatively short wavelength light source such as a fluorescent lamp and a long wavelength light source such as a semiconductor laser.

Still another object of the present invention is to provide light irradiation.
It is an object of the present invention to provide an electrophotographic photosensitive member which does not change the charging characteristics, does not increase the residual potential, and has a constant sensitivity.

[0013]

In order to achieve the above object, the inventors of the present invention have earnestly studied an improvement method for this kind of deterioration, and as a result, an electrophotographic photosensitive material having a photosensitive layer on a support. In the body, at least in the charge generation layer, the diffraction angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction is 9.0.
Either or both of oxytitanium phthalocyanine having a strong peak at °, 14.2 °, 23.9 °, and 27.1 ° or an azo pigment of the following structural formula (A), or both, and the following general formulas (1) and ( By containing the polycarbonate resin containing the repeating unit represented by 2), it becomes possible to provide an electrophotographic photosensitive member having stable electric characteristics for repeated use.

[0014]

Embedded image

[0015]

Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a cycloalkyl group having 6 to 12 carbon atoms. It is an aryl group, and a, b, c and d are each independently 0.
-4.

X in the formula is —CR ₅ R ₆ — (wherein R ₅ and R ₆ are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, or a carbon atom having 6 to 12 carbon atoms).
Is an aryl group. ), A 1,1-cycloalkylene group having 5 to 11 carbon atoms, an α, ω alkylene group having 2 to 10 carbon atoms, a single bond, —O—, —S—, —SO ₂ —, —SO—. The electrophotographic apparatus and the apparatus unit using the electrophotographic photoreceptor have sufficient sensitivity to a relatively short wavelength light source such as a fluorescent lamp and a long wavelength light source such as a semiconductor laser, and the charging The charging characteristics do not change even after repeated use, such as exposure, and there is no increase in residual potential.
An electrophotographic photosensitive member having a constant sensitivity, an electrophotographic apparatus using the same, and an apparatus unit have been provided.

In the electrophotographic photoreceptor of the present invention, examples of repeating units of the polycarbonate resin contained in the photosensitive layer include the following.

Regarding the general formula (2),

[0019]

Embedded image

[0020]

Embedded image

[0021]

[Chemical 12]

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image And the like. Regarding the general formula (1),

[0029]

Embedded image

[0030]

[Chemical 21]

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

[Chemical formula 26]

[0036]

Embedded image And the like.

In the electrophotographic photosensitive member of the present invention, the following structures can be mentioned as particularly preferable structures of the polycarbonate resin contained in the photosensitive layer, but the respective molar ratios are limited thereto. is not.

[0038]

Embedded image

[0039]

[Chemical 29]

[0040]

Embedded image

[0041]

[Chemical 31] In the polycarbonate resin used for the electrophotographic photosensitive member of the present invention, the content ratio of the repeating unit represented by the general formula (1) is represented by the repeating unit represented by the general formula (1) and the general formula (2). The molar ratio is preferably 1 to 90% with respect to the total of repeating units. Molar ratio less than 1%,
When it is more than 90%, when the resin is dissolved in a solvent to prepare a coating solution, a part of the resin is likely to crystallize, and the coating solution gels over time during coating and is not suitable as a binder. When the photoreceptor is continuously produced for a long time (8 hours or more), the molar ratio of the repeating unit represented by the general formula (1) is 5
It is preferably about 50%. Although the repeating unit represented by the general formula (1) contained in the polycarbonate resin used in the electrophotographic photoreceptor of the present invention may be composed of only one kind, the kind of the substituents of R ¹ and R ² and Two or more kinds of repeating units represented by the general formula (1) having different numbers of a and b substituents may be contained. The same applies to the repeating unit represented by the general formula (2).

The polycarbonate resin used in the electrophotographic photoreceptor of the present invention is a repeating unit other than the repeating units represented by the general formula (1) and the general formula (2) as long as the object of the present invention is not impaired. May be included.

In the present invention, examples of the constitution of the photosensitive layer of the electrophotographic photoreceptor containing the polycarbonate resin include:
In the case of a single layer photoreceptor, it is used for the entire photosensitive layer. At this time,
The photosensitive layer has at least a diffraction angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction of 9.0 °, 14.2 °, 2
Either or both of the oxotitanium phthalocyanine having a strong peak at 3.9 ° and 27.1 ° or the azo pigment of the structural formula (A) or both of them can be contained and adapted.

In the case of a laminated photoreceptor in which a charge generating layer is laminated on a conductive support and a charge transporting layer is laminated thereon, the polycarbonate resin is applied to at least the charge transporting layer, and CuKα is used as the charge generating layer. Diffraction angle 2θ in characteristic X-ray diffraction
± 0.2 ° is 9.0 °, 14.2 °, 23.9 °, 2
Either or both of the oxotitanium phthalocyanine having a strong peak at 7.1 ° and the azo pigment of the structural formula (A), or both of them can be contained and adapted.

Further, in the case of a photoreceptor having a protective layer provided on the charge transport layer, examples of application to the charge transport layer and / or the protective layer can be given.

In the present invention, when a polycarbonate resin is contained in the surface layer, it has an effect of reducing surface abrasion and scratches.

As the binder resin of the surface layer used in the photoreceptor of the present invention, only the polycarbonate resin composed of the repeating units represented by the general formulas (1) and (2) may be used alone, but the object of the present invention is Other binder resins may be mixed as necessary within the range that does not hinder the above. Examples of the binder resin to be mixed include polycarbonate resins having other structures (for example, polycarbonate resins made from bisphenol A and bisphenol Z as raw materials), and acrylic resins, polyester resins, polyamide resins, polyvinyl acetate as other types of resins. Resin, thermoplastic resin such as polyvinyl butyral resin; polyurethane resin, phenol resin,
Thermosetting resin such as epoxy resin; photo-curing resin and the like can be mentioned.

However, if the amount of the other resin mixed is too large, the resin is liable to wear and the effect of the present invention cannot be sufficiently obtained. The mixing ratio of the polycarbonate resin of the present invention is 30% (% by weight) or more, particularly preferably 50%, based on the total amount of the binder resin.
The above is necessary.

The details of the present invention will be described below.

Specific examples of the present invention include a single-layer photoconductor, a laminated photoconductor in which charge generation and charge transport are functionally separated, and a photoconductor further provided with a surface protective layer. The most preferable examples are as follows. , A laminated photoreceptor in which the functions of charge generation and charge transport are separated.

Examples of the material of the electroconductive substrate used in the electrophotographic photoreceptor of the present invention include metals such as aluminum, copper, nickel and silver or alloys thereof; electroconductivity such as antimony oxide, indium oxide and tin oxide. Examples include metal oxide, carbon fiber, carbon black, and a mixture of graphite powder and resin and molding.

Furthermore, it is possible to provide a conductive layer on the substrate for covering defects on the substrate and protecting the substrate. For example, metal powder of aluminum, copper, nickel, silver, etc .;
Conductive metal oxides such as antimony oxide, indium oxide, and tin oxide; polymer conductive materials such as polypyrrole, polyaniline, and polymer electrolytes; carbon fiber, carbon black, graphite powder; or conductive materials whose surfaces are coated with these conductive materials. Conductive materials such as conductive powder are thermoplastic resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, polyvinyl butyral resin; thermosetting resin such as polyurethane resin, phenol resin, epoxy resin; Examples thereof include those dispersed in a binder resin such as a cured resin, and those coated with a base material to which additives are added as required.

If necessary, a barrier layer of polyamide, polyurethane, epoxy resin, aluminum oxide or the like may be provided between the conductive substrate and the photosensitive layer.

As the charge generating material used in the charge generating layer, at least the diffraction angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction is 9.0 °, 14.2 °, 23.9.
May contain either or both of an oxotitanium phthalocyanine having a strong peak at 20 ° and 27.1 ° or an azo pigment of the following structural formula (A), or by mixing one or more other organic pigments. Good.

[0055]

Embedded image Further, a binder resin is added if necessary. Examples of the binder resin include thermoplastic resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, and polyvinyl butyral resin; thermosetting resins such as polyurethane resin, phenol resin, and epoxy resin; photocurable resin. And so on.

In forming the charge transport layer, generally, a solvent is added to the charge transport substance and the binder resin to prepare a coating solution, which is coated by a coating means to form a photoreceptor.

Examples of the material for the charge transport layer include hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds and triarylamine compounds.

As the solvent used at this time, a solvent having a good solubility in the binder resin and the charge transfer agent is selected. Particularly preferable examples are ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone. Ethers such as diethyl ether and tetrahydrofuran. Esters such as ethyl acetate and butyl acetate.
Hydrocarbons such as toluene and benzene. Examples thereof include halogenated hydrocarbons such as chlorobenzene and dichloromethane.

Examples of the binder material for the charge generating layer include, in addition to the polycarbonate used in the present invention, thermal resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, polyvinyl butyral resin, and polyvinyl bubenzal resin. Examples of the plastic resin include those dispersed in a binder resin such as thermosetting resin such as polyurethane resin, phenol resin and epoxy resin, and those dispersed in a suitable solvent and applied. Further, it is possible to add additives as required.

The ratio of the charge transfer agent to the binder resin depends on the type of the binder resin and the charge transfer agent, but is generally 20 to 70%, particularly preferably 30 to 65%. When the ratio of the charge transfer agent is small, sufficient sensitivity cannot be obtained. On the other hand, if the ratio of the charge transport agent is too high, the strength of the surface layer is lowered and the surface layer is easily damaged. Further, if necessary, an inorganic filler or a lubricant such as polyethylene, polyfluoroethylene or silica may be added to the surface layer. The ratio of the lubricant to the binder resin is 0.1% to 50%, particularly preferably 1
３０30%. Further optional additives such as: dispersion aid, silicone oil, leveling agent, metallic soap,
It is also possible to add a silane coupling agent or the like.

If necessary, an additive such as an electron-withdrawing substance, an electron-donating substance or an ultraviolet absorber and an antioxidant may be added to the charge generation layer and the charge transport layer.

As the coating method used in the present invention, a dip coating method, a spray coating method, a roll coater coating method, a gravure coater coating method and the like can be applied.

FIG. 1 shows a schematic structural example of a transfer type electrophotographic apparatus using the electrophotographic photosensitive member of the present invention. In the figure,
Reference numeral 1 is a drum type photoreceptor of the present invention, which is rotationally driven around the shaft 1a at a predetermined peripheral speed. The photosensitive member 1 is uniformly charged at its peripheral surface by a charging unit 2 at a predetermined positive or negative potential in the course of its rotation, and then, in an exposure unit 3, an optical image exposure L (slit exposure, slit exposure, Laser beam scanning exposure). As a result, electrostatic latent images corresponding to the exposed image are sequentially formed on the peripheral surface of the photosensitive member. The electrostatic latent image is developed with toner by the developing unit 4, and the toner development is synchronized with the rotation of the photoconductor 1 between the photoconductor 1 and the transfer unit 5 from a paper feeding unit (not shown) by the transfer unit 5. Then, they are taken out and sequentially transferred onto the surface of the fed transfer material 9. The transfer material 9 on which the image has been transferred is separated from the surface of the photoconductor and introduced into the fixing means 8 to be printed out as a copy.

The surface of the photoconductor 1 after transfer is cleaned by the cleaning means 6 to remove the residual toner after transfer, and is further discharged by the pre-exposure means 7 for repeated image formation.

As a uniform charging means for the photoconductor 1, a corona charging device, a roller charging device, etc. are generally used.
A corona charging device, a roller charging device and the like are also commonly used as the transfer means. An electrophotographic apparatus is configured by integrally combining a plurality of constituent elements such as the above-described photoconductor, charging means, developing means, and cleaning means as an apparatus unit (generally, this apparatus unit is called a cartridge). The unit may be detachably attached to the apparatus body. For example, the photosensitive member 1, the charging unit 2, the developing unit 8 and the cleaning unit 6 may be integrated into one apparatus unit and configured to be detachable by using a guide unit such as a rail of the apparatus body.

Examples of the image exposure L include reflected light from an original when used as a copying machine, scanning of a laser beam when used as a printer, LED array driven by electric signals, liquid crystal shutter array and the like.

The electrophotographic photosensitive member of the present invention can be applied to a photosensitive drum generally used in electrophotographic devices such as copying machines, laser printers, LED printers and liquid crystal shutter printers.

[0068]

EXAMPLES Next, the present invention will be described with reference to examples.

(Example 1) A solution prepared by dissolving 5 parts of 6-66-610-12 quaternary polyamide copolymer resin in a mixed solution of 70 parts of methanol and 25 parts of butanol was prepared to give a diameter of 30 m.
An undercoat layer having a thickness of 0.65 μm was provided by coating and drying on a m × 254 mm aluminum cylinder by a dipping method.

Next, the diffraction angle 2θ ± 0.
2 ° is 9.0 °, 14.2 °, 23.9 ° and 27.
Polyvinyl butyral resin (trade name: S-REC BX-1, 5 parts of TiO-Pc crystal having a strong peak at 1 °)
Sekisui Chemical Co., Ltd.) 5 parts and cyclohexanone 100 parts dissolved in a liquid, dispersed with a sand mill using 1 mmφ glass beads, added with 200 parts ethyl acetate and diluted, and then applied on the undercoat layer After that, it was dried at 80 ° C. for 10 minutes to form a charge generation layer having a film thickness of 0.25 μm.

Further, 10 g of a polycarbonate resin having the following structural formula,

[0072]

[Chemical 33] 10 g of the charge transport material having the following structural formula,

[0073]

Embedded image It is dissolved in 80 g of methylene chloride, and the resulting solution is applied on the above charge generation layer by a dipping method, and the solution is applied at 110 ° C. for 1 hour.
By drying for 24 hours, a charge transport layer having a thickness of 24 μm was formed to prepare a laminated electrophotographic photoreceptor.

Example 2 A photoconductor was prepared in the same manner as in Example 1 except that the polycarbonate resin having the following structural formula (molecular weight 80000) was used.

[0075]

Embedded image (Example 3) A photoreceptor was prepared in the same manner as in Example 1 except that the polycarbonate resin having the following structural formula (molecular weight: 60000) was used.

[0076]

Embedded image (Example 4) A photoconductor was prepared in the same manner as in Example 1 except that the polycarbonate resin having the following structural formula was used.

[0077]

Embedded image (Example 5) In Example 1, 4 parts of oxytitanium phthalocyanine used for the charge generation layer, having the following structure

[0078]

Embedded image A photoconductor was formed in the same manner as in Example 1 except that the charge generation layer was formed by using 1 part of the azo pigment of 1) and the polycarbonate resin used for the charge transport layer had the following structure.

(Comparative Example 1) A photosensitive member was prepared in the same manner as in Example 1 except that the polycarbonate resin (molecular weight 40,000) having the following structural formula was used.

[0080]

Embedded image (Comparative Example 2) In Example 1, the diffraction angles 2θ ± 0.2 ° in X-ray diffraction were 9.3 °, 10.6 °, and 13.2.
°, 15.1 °, 20.8 °, 23.3 °, 27.1 °
A photoconductor was prepared in the same manner as in Example 1 except that a TiO-Pc crystal having a strong peak was used.

Example 6 A photoconductor was prepared in the same manner as in Example 1 except that the azoxy pigment shown below was used instead of the oxytitanium phthalocyanine used in Example 1.

[0082]

Embedded image (Comparative Example 3) A photoconductor was prepared in the same manner as in Example 6 except that the polycarbonate resin (molecular weight 40,000) used in the charge transport layer in Example 6 had the following structure.

[0083]

Embedded image Each of the above photoconductors was evaluated as follows.

With respect to the exposure amount and charging conditions of the Canon LBP-SX, the surface potential Vd _{0 in the} dark was 600 V and the surface potential Vl _{0 in the} exposure was 1 when the photoconductors of the above-mentioned examples and comparative examples were mounted.
It was set to 70V. The initial dark surface potential Vd ₀ , the initial residual potential Vsl ₀ , the surface potential Vd ₁₀ after obtaining 100 million images, the surface potential Vl ₁₀ during exposure at that time, and the residual potential Vsl ₁₀ And the characteristics of the photoconductors of Comparative Examples were evaluated.

The evaluation of the photoconductors of Example 6 and Comparative Example 3 was carried out according to the above evaluation method using Canon NP-2020.

[0086]

[Table 1]

[0087]

According to the present invention as described above,
In an electrophotographic photoreceptor having a photosensitive layer on a support, the charge generation layer has at least a diffraction angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction of 9.0 °, 14.2 °, 2
Either or both of the oxytitanium phthalocyanine having a strong peak at 3.9 ° and 27.1 ° or the azo pigment of the structural formula (A), or both of them and the general formula (1).
And containing the polycarbonate resin containing the repeating unit represented by (2), the residual potential is small,
It is possible to obtain an electrophotographic photoreceptor having stable quality and high durability, which has little potential fluctuation even after repeated use.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic image forming apparatus using an electrophotographic photosensitive member of the present invention.

[Explanation of Codes] 1 drum type photoreceptor 1-a drum shaft 2 charging means 3 exposure part 4 developing means 5 transfer means 6 cleaning 7 pre-exposure means 8 fixing means 9 transfer paper L image exposure

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Kitamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Fumio Sumino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a support, wherein at least a CuKα characteristic X-ray diffraction angle of 2θ ± 0.
2 ° is 9.0 °, 14.2 °, 23.9 °, 27.1
One or both of oxytitanium phthalocyanine having a strong peak at ° and an azo pigment of the following structural formula (A) and a polycarbonate resin containing a repeating unit represented by the following general formulas (1) and (2). An electrophotographic photoreceptor containing the same. Embedded image Embedded image Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms or a cycloalkyl group having 6 to 12 carbon atoms. It is an aryl group, and a, b, c and d are each independently 0.
-4. X in the formula is -CR ₅ R _6- (however,
R ₅ and R ₆ are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, or a carbon atom having 6 to 6 carbon atoms.
12 aryl groups. ), 1, 1 having 5 to 11 carbon atoms
-Cycloalkylene group, α, ω alkylene group having 2 to 10 carbon atoms, single bond, -O-, -S-, -SO _2- , -SO
− ) 2. The polycarbonate resin contained in the photosensitive layer comprises a repeating unit represented by the general formula (1) and the general formula (2), and contains a repeating unit represented by the general formula (1). The electrophotographic photosensitive member according to claim 1, wherein the ratio is 1 to 90% by molar ratio with respect to the total of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2). . 3. The child photographic photoreceptor according to claim 1, wherein the polycarbonate resin contained in the photosensitive layer comprises a repeating unit represented by the following structural formula. Embedded image Embedded image [Chemical 6] [Chemical 7] 4. An electrophotographic apparatus provided with the electrophotographic photosensitive member according to claim 1. 5. A charging unit constituting an electrophotographic apparatus
An electrophotographic apparatus unit comprising a combination of at least one of a developing unit, a transfer unit, and a cleaning unit, and the electrophotographic photosensitive member according to claim 1.