JPH01134367A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent deterioration of electrifiability of a photosensitive layer of an electrophotographic sensitive body even if it is used repeatedly by incorporating a specified charge transfer material and hydroquinone (or its derivative) into the photosensitive layer. CONSTITUTION:A compd. expressed by formula I as a charge transfer material and hydroquinone (or its deriv.) are contained in a photosensitive layer. In formula I, each R<1> and R<4> is H, alkyl group, halogen atom., etc.; each R<2> and R<3> is H, alkyl group, or phenyl group; X is a benzene ring, naphthalene ring, or indole ring; n is 0 or 1; m is 0-3. A compd. expressed by formula II is used for the compd. expressed by the formula I, and a phthalocyanine compd. etc., is used for a charge generating material. When the photosensitive layer is constituted of a function-separating type photosensitive body, the hydroquinone (or its deriv.) may be incorporated into either a charge generating layer or a charge transfer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor that has excellent charging stability even when used repeatedly over a long period of time.

[Prior Art] Inorganic materials such as selenium, hydridium sulfide, and zinc oxide have been conventionally known as photoconductive materials for electrophotographic photoreceptors. However, these inorganic substances are required as electrophotographic photoreceptors. Properties such as photosensitivity, thermal stability, and durability, as well as manufacturing conditions, are not always satisfactory. For example, selenium tends to crystallize due to heat, dirt, etc., and its properties tend to deteriorate. In addition, it has drawbacks such as manufacturing cost, impact resistance, toxicity, and other issues that require careful handling. Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Zinc oxide also has the disadvantage of being inferior in moisture resistance and durability.

For electrophotographic photoreceptors using these inorganic photoconductive materials,
Photoreceptors using organic photoconductive substances are being actively researched and developed because of their light weight, ease of film formation, manufacturing cost, and wide variation as organic compounds. For example, in the early days, a photoreceptor containing polyvinylcarbazole and 2,4,7-dolinitro-9-fluorenone described in Japanese Patent Publication No. 50-10496,
A photoreceptor in which polyvinylcarbazole is sensitized with a biryllium base dye as described in the publication No. 658@, and a photoreceptor having a eutectic complex as a main component have been proposed. However, these photoreceptors do not have sufficient sensitivity and durability. Therefore, in recent years, a functionally separated type photoreceptor in which a charge generation layer and a charge transport layer are separated has been proposed. Described in JP-A-53-133445, JP-A-54-2
1728, JP-A-54-22834, charge transport materials include JP-A-58-198043,
Japanese Unexamined Patent Publication No. 58-199352 is known.

However, these function-separated type photoreceptors are not particularly satisfactory in terms of durability, and in recent years, as demands for durability have been increasing more and more, ensuring charging stability has become a problem that cannot be ignored.

That is, if the charging property is reduced, the image density of the copy will be reduced in a copying machine, and the image quality will be degraded, such as background staining, in the case of a laser printer using reversal development.

In order to solve these problems, it has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize the charging property, although the charging property is improved, there are drawbacks such as a decrease in photosensitivity and an increase in the residual potential.

Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, charging stability will be insufficient.

[Purpose] In view of the above circumstances, it is an object of the present invention to provide a photoconductor with excellent charging stability that does not deteriorate in charging property even after repeated use.

[Structure] The present inventor has been conducting research to solve the above problems, and found that it is possible to contain a combination of a specific group of compounds as a charge transporting substance and hydroquinone or a derivative thereof in a photosensitive layer. It was discovered that this method is effective, leading to the present invention.

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing a charge-generating substance and a charge-transporting substance on a conductive support, wherein the charge-transporting substance is a compound represented by the following formula (I>). An electrophotographic photoreceptor characterized in that the photosensitive layer contains hydroquinone or a derivative thereof.

In the formula, R1 and R4 represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or an unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, and R5 and R6 may form a ring) , R2 and R3 are hydrogen atoms, alkyl groups or substituted or unsubstituted phenyl groups, X is benzene ring, naphthalene ring or indole ring, N is O or 1, m is 0,1
゜Indicates 2 or 3.

Hydroquinone or its derivatives used in the present invention include hydroquinone, methylhydroquinone, 2.
3-dimethylhydroquinone, 2.5-dimethylhydroquinone, trimethylhydroquinone, 2.5-di-amylhydroquinone, t-butylhydroquinone, 2.
5-di-t-butylhydroquinone, 2.5-di-amylhydroquinone, chlorohydroquinone, 2.5-di-t-octylhydroquinone, 2-j-butyl-5-
Methylhydroquinone, 1,4-diolnaphthalene,
Examples include HQR conductors such as 9.10-diolanthracene.

Further, as the charge transport substance of formula (1) used in the present invention, for example, Table 1 Ko (CH2) Ko CH Ko C (13 C2HI U (Working CIl Ko58 0 H (door) 2 59 0 t-1GN+oCI+3) 2600H
-@door 602 n) 2 61 0 8 GN@(CI+2 > 2
CI+3] 2e2 o+-@door [◎C(C
113) 3 ] 2 (Cl12) 2 C1l fcllz ) 2 CHz lcH2)2 CHz (CI+2) 3 C1h 1190H M(C2Hs) 2 may be mentioned, but is not limited to these.

Examples of the charge-generating substance include organic compounds shown in (1) to (4) below.

■ Perylene pigments such as perylene anhydride and perylene imide.

■ Indigo pigment.

■ Quinacridone pigment.

■ Polycyclic quinones such as Anne 1 - laquinones, pyrenequinones, anthoanthros, and flavanthrones.

■Bisbenzimidazole pigment.

■　Square medicine pigment.

■ Indathlon pigment.

■ Phthalocyanine pigments such as metal phthalocyanines such as copper phthalocyanine and metal-free phthalocyanines.

■ Azo pigments such as monoazo, disazo and triazo pigments. Examples of monoazo pigments include monoazo pigments having a central skeleton of anthraquinone, N-phenylcarbazole, etc.; examples of disazo pigments include benzidine pigments such as Diane Blue and Chlordiane Blue; naphthalene, fluorenone, fluorene,
There are disazo pigments having central skeletons such as anthraquinone, 2,5-cyphenyne-1.3.4-oxadiazole, dibenzothiophene, dibenzodiphene dioxide, acridone, and phenanthrenequinone. Examples of trisazo pigments include triphenyl Amine or N-
There are trisazo pigments that have a central skeleton such as phenylcarbazole.

[Co., Ltd.] Azulenium Salt Compound etc. are required.

The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a dispersed type or a functionally separated type in which a charge generating substance and a charge transporting substance are combined. As for the layer structure, in the case of a separate type, a photosensitive layer in which a binder, a charge generating substance, and a charge transporting substance are dispersed is provided on a conductive substrate. In the case of a functionally separated type, a charge generation layer containing a charge generation substance and a binder is formed on the substrate, and a charge transport layer containing a charge transport substance and a binder is formed on top of the charge generation layer. The layers can be reversed (positively charged type)
. Furthermore, an intermediate layer may be interposed between the photosensitive layer and the substrate to improve adhesion or charge blocking properties. Furthermore, a protective layer may be provided on the photosensitive layer in order to improve mechanical durability such as abrasion resistance.

Note that the charge transport material may be contained in the charge generation layer. Especially in the case of a positively charged configuration, the sensitivity is good.

Binders used in forming the charge generation layer, charge transport layer and dispersed photosensitive layer include polycarbonate, polyester,
Methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenol resin, epoxy resin, polyurethane, vinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, etc. are used. These binders can be used alone or as a mixture of two or more.

When a photoreceptor is constructed using the above-mentioned layer-constituting materials, there is a preferable range for the film thickness and the ratio of the materials.

In the case of a negatively charged type (substrate-charge generation layer-charge transport layer), the ratio of the charge generation substance to the binder in the charge generation layer is preferably 20 to 500% by weight, and the film thickness is preferably 0.1 to 10 μm. In the charge transport layer, the ratio of the charge transport material to the binder is preferably 20 to 200%, and the film thickness is preferably 5 to 50 μm.

In the case of the positively charged reverse layer type, the ratio of the charge transport substance to the binder in the charge transport layer on the substrate side is preferably 20 to 200% by weight, and the film thickness is preferably 5 to 50 μm.

In the charge generation layer, the charge generation substance is added to the binder resin in an amount of 10
It is preferable to contain up to 100% by weight, but it is also preferable to also include a charge transport substance, and by containing 20 to 200 @ 1 part to the binder resin, the residual potential is small and sensitivity is good. becomes.

When adding hydroquinone to the charge transport layer in a functionally separated type, the amount of hydroquinone added to the photosensitive layer is 0.01 to 5.0% relative to the charge transport material. Ovt% is desirable. When added to the charge generation layer, the amount is 0.1 to 2% relative to the charge generation substance.
It is desirable to set it to 0.0 wt%. In the case of a dispersed type, the charge transport material is 0.01 to 5. It is desirable to set it as ONv%.

The intermediate layer, which is provided as needed, is generally made mainly of resin, but considering that a photosensitive layer is attached on top of it using a solvent, it is recommended to use a resin that has high solvent resistance to general organic solvents. is desirable. As such resin,
Forms a three-dimensional network structure of water-soluble resins such as polyvinyl alcohol, casein, sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon, methoxymethylated nylon, polyurethane, melamine resin, alkyd resin, phenolic resin, epoxy resin, etc. Examples include curable resins.

In addition, the intermediate layer contains titanium oxide, silica, alumina, zirconium oxide, etc. to prevent moire and reduce residual potential.
Fine powder pigments of gold RJn compounds such as tin oxide and indium oxide may also be added.

Further, examples of the solvent or dispersion medium used in forming the charge generation layer and charge transport layer of the present invention include N,N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1゜2-dichloroethane, dichloromethane,
Examples include monochlorobenzene, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, and the like.

Substrates used in the electrophotographic photoreceptor of the present invention include metal drums and sheet-like substrates made of aluminum, brass, stainless steel, N1, and the like. Alternatively, metals such as AI and Ni are deposited on materials such as polyethylene terephthalate, polypropylene, nylon, and paper, or conductive substances such as titanium oxide, tin oxide, and carbon black are coated with a suitable binder. Examples include sheet-like or cylindrical substrates such as electrically conductive treated plastics and paper.

The electrophotographic photoreceptor produced with the above configuration does not deteriorate in photoreceptor characteristics such as charging stability even after long-term use, and no deterioration is observed in images.

Examples of the present invention are shown below.

Examples 1-3 Alcohol-soluble polyamide (Amilan C)! -800
0: manufactured by Toshi) was dissolved in a mixed solvent of 8 parts by weight of methanol and 5 parts by weight of n-butanol.

To this was added 3 parts by weight of titanium oxide powder (Tie Bake A-100, manufactured by Ishihara Sangyo) and dispersed in a ball mill for 12 hours to prepare a coating liquid for an intermediate layer. This is the major axis of 40m and the length is 25
It was coated on a 5 m aluminum drum by dip coating and dried to form an intermediate layer with a thickness of 2 μ7 nm.

Next, polyvinyl butyral resin [S-LEC 81-3
(manufactured by Kensui Kagaku Kogyo)" was dissolved in 125 parts by weight of 1.2 dichloromethane, and 1 part by weight of X-type metal-free phthalocyanine prepared in the same manner as described in Japanese Patent Publication No. 49-4338. was added and dispersed using an ultrasonic disperser. The charge generation layer coating solution thus obtained was applied onto the intermediate layer by dip coating and dried to a film thickness of 0.5 μm.
A charge generation layer was formed.

Further, 8 parts by weight of a charge transport substance represented by the following structural formula (II) polycarbonate resin (-130
0; manufactured by Yojin Kasei Co., Ltd.) 10 parts by weight silicone oil (KF-
Example 1 Methylhydroquinone Example 22.5-di-tert- Butylhydroquinone Example 3 1.4-diolnaphthalene A coating solution for charge transport layer was prepared. This was coated on the charge generation layer by dip coating and dried to form a charge transport layer with a thickness of 20 μm.

Comparative Examples 1 to 3 Photoreceptors were produced in the same manner as in Examples 1 to 3, except that the additives added to the charge transport layer in Examples 1 to 3 were changed to the following.

Comparative Example 12. 6-tert-butyl-4-methylphenol Comparative Example 24. 4-thiobis(3-methyl-6-tert
-butylphenol) Comparative Example 3 Example 4 without additives Example 1 except that methyl hydroquinone was added to the charge generation layer of Example 1 in awt% based on the charge generation substance, and methyl hydroquinone was roughly removed from the charge transport layer. A photoreceptor was created in exactly the same manner as above.

The photoreceptor obtained above was printed using a laser printer (PC-LA).
The photoreceptor was evaluated. Evaluation was performed by measuring the image after 20,000 copies and the surface potential of the photoreceptor. The surface potential was measured by removing the developing device and attaching a surface electrometer to the developing position.

As described above, the samples to which a hydroquinone derivative was added exhibited stable charging characteristics, while the surface potential of the non-exposed areas of the other samples decreased significantly. Since this laser printer uses a reversal development method, when the surface potential decreases, background smudges occur in non-exposed areas, as seen in the comparative example.

Example 5 In the same manner as in Example 2, an intermediate layer was formed on an aluminum drum, and the charge transport layer coating solution of Example 2 was applied onto the intermediate layer and dried to create a charge transport layer with a thickness of 20 μm. did.

Next, polycarbonate resin (Panrai I-L-1250
; manufactured by Yojin Kasei) 4 parts by weight of 162-dichloroethane 20
The mixture was dissolved in 200 parts by weight of 1,1.2-trichloroethane, and 1 part by weight of the x-type metal phthalocyanine shown in Example 1 was added thereto and dispersed using an ultrasonic disperser. Furthermore, the charge transport substance (I) shown in Example 1 is added to the dispersion liquid.
) was added and dissolved to prepare a charge generation layer coating solution.

This was spray-coated on the charge transport layer and dried to form a charge generation layer with a thickness of 3 μTrt to prepare an electrophotographic photoreceptor.

Comparative Example 4 A photoreceptor was prepared in the same manner as in Example 5 except that 2,5-di-tert-butylhydroquinone was removed from the charge transport layer of Example 5.

Example 6 In the same manner as in Example 1, an intermediate layer was formed on an aluminum drum. Polycarbonate resin (-1 for panlite)
300: Konjin Kasei'! 20 parts by weight was dissolved in 250 parts by weight of 1,2-dichloroethane, and the mixture shown in Example 1 was added to
Five parts of metal-free phthalocyanine were added and dispersed using an ultrasonic disperser. Furthermore, the following structural formula (I
I).

0.1 part by weight of doquinone was added and dissolved to prepare a photosensitive layer coating solution. Applying this liquid onto the intermediate layer using a dip coating method,
It was dried to form a photosensitive layer with a thickness of 16 μm, and a photoreceptor was prepared.

Comparative Example 5 A photoreceptor was prepared in the same manner as in Example 6 except that 2,5-di-amylhydroquinone was removed.

In Examples 5 and 6 and Comparative Examples 4 and 5, the photoreceptor was evaluated using a modified laser printer (PC-LASER-6000).

The modification includes reversing the polarity of the charger and various biases.
In addition, the charger, quenching lamp, and laser writing system were made to operate even without paper passing.

Furthermore, the number of developed images was removed and a surface electrometer was attached thereto.

Initial and photoreceptor 1000 with the above modified laser printer
The surface potential of the photoreceptor after 0 rotation was measured.

[Effects] As explained above, the photoreceptor of the present invention has good charging stability and is free from image defects such as a decrease in image density and scumming even after repeated use.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support, wherein the charge transporting substance is a compound represented by the following general formula (I),
An electrophotographic photoreceptor characterized in that the photosensitive layer contains hydroquinone or a derivative thereof. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) In the formula, R^1 and R^4 are hydrogen atoms, alkyl groups, alkoxy groups, halogen atoms, or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R^5 , R^6 represents an alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, R^5 and R^6 may form a ring), R^2, R^ 3 is a hydrogen atom,
an alkyl group or a substituted or unsubstituted phenyl group,
X is a benzene ring, naphthalene ring or indole ring,
n represents 0 or 1; m represents 0, 1, 2 or 3;