JPH03191359A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body high in sensitivity, small in deterioration of electric chargeability due to preexposure fatigue, and free of delay in rising to chargeable potential even after repeated cycles of charging and exposure by incorporating a specified compound in a charge transfer layer. CONSTITUTION:The charge transfer layer contains the compounds represented by formulae I and II in which R<1> is optionally substituted alkyl or such aryl; each of R<2> - R<4> is H, optionally substituted alkyl, or the like; Ar<1> is optionally substituted aryl; Ar<2> is optionally substituted arylene; Ar<1> and R<2> may form a ring together with each other; (n) is 0 or an integer of 1; each of R<5>-R<7> is H, lower alkyl, or the like; and (m) is 0 or 1, thus permitting the obtained electrophotogrpahic sensitive body to be high in sensitivity, small in deterioration of chargeability due to preexposured, moreover, underterioratd in chargeability characteristics even after repeated cycles of charging and exposure.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in electrophotographic photoreceptors.

[Conventional technology]

In recent years, organic photosensitive materials, which have advantages such as low cost, productivity, and non-pollution, have become popular as photoconductors used in electrophotographic copying machines.

Organic electrophotographic photoreceptors include photoconductive resins such as polyvinylcarbazole (PVK), and PVK-TNF.
(2,4,7-dolinitrofluorenone), pigment-dispersed type as represented by cyanine-binder, and functionally separated type using a combination of a charge-generating substance and a charge-transporting substance. In particular, functionally separated photoreceptors are attracting attention.

When such a functionally separated high-sensitivity photoreceptor is applied to the Carlson process, it has low chargeability and poor charge retention (high dark decay), and these characteristics deteriorate significantly with repeated use, resulting in poor image quality. above.

It has the drawbacks of density unevenness, fog, and in the case of reversal development, scumming.

Furthermore, in general, high-sensitivity photoreceptors have reduced chargeability due to pre-exposure fatigue. This pre-exposure fatigue is mainly caused by light absorbed by the charge-generating material, so the longer the charges generated by light absorption remain in the photoconductor in a mobile state, the more the number of charges increases. It is thought that the lower the chargeability becomes, the more the chargeability decreases due to pre-exposure fatigue. In other words, even if a charging operation is performed while the charge generated by light absorption remains, the surface charge will be neutralized by the movement of the remaining carriers, so the surface potential will increase until the residual charge is consumed. do not. Therefore, the rise in surface potential is delayed by the amount of pre-exposure fatigue, and the surface potential becomes lower.

For the above-mentioned drawbacks, for example, Japanese Patent Application Laid-Open No. 47-6341.
Nos. 48-3544 and 4g-12034 have cellulose nitrate resin intermediate layers, as disclosed in JP-A No. 48-47344.52.
-25638.58-30757.58-63945.
5g-95351, 58-98739 and 60-66
No. 258 has a nylon resin intermediate layer, which is disclosed in Japanese Patent Application Laid-Open No. 49-6
Nos. 9332 and 52-10138 disclose a maleic acid resin intermediate layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin intermediate layer.

In addition, intermediate layers have been proposed in which various conductive additives are contained in a resin in order to control the electrical resistance of the intermediate layer. For example, JP-A-51-65942 discloses an intermediate layer in which carbon or chalcogen-based substances are dispersed in a curable resin, and JP-A-52-82238 discloses an incyanate-based curing agent by adding a quaternary ammonium salt. The thermopolymer intermediate layer used is a resin intermediate layer containing a resistance modifier in JP-A-55-1.180451, and a resin in which aluminum or tin oxide is dispersed in JP-A-58-58556. The intermediate layer is a resin intermediate layer added with an organometallic compound in JP-A-58-93062, and JP-A-58-93063.60-973
63 and 60-1.11255 have a resin intermediate layer in which conductive particles are dispersed, and JP-A-59-84257.
Nos. 59-93453 and 60-32054 contain TiO
A resin intermediate layer in which No. 2, SnO, and powder are dispersed is disclosed.

Furthermore, based on the idea of controlling charge mobility instead of electrical resistance, a resin intermediate layer containing an electron-accepting organic compound as a negative charge mobility substance has been proposed. For example, JP-A No. 53-89433 discloses an organic polymer photoconductor intermediate layer containing a polycyclic aromatic nitro compound;
No. 47 and No. 59-170846 disclose resin interlayers containing electron-accepting organic substances.

However, it is still insufficient in terms of the deterioration in chargeability due to repeated use, especially the delay in the rise of the 4th charge, and further improvements have been desired.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that is highly sensitive, exhibits significantly less deterioration in chargeability due to pre-exposure fatigue, and has no delay in the rise of charging potential even after repeated charging and exposure. do.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer laminated on a conductive substrate, the charge transport layer is represented by the following general formula (1) and general formula (II). Provided is an electrophotographic photoreceptor characterized by containing a compound.

(In the formula, R1 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, R2, R3 and R4 represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, Ar1 represents a substituted or unsubstituted aryl group, and Ar" represents a substituted or unsubstituted arylene group. Ar1 and R1 may jointly form a ring, n is an integer of 0 or l.) (Formula Medium, Rs, R'
, R7 represents hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group, or a hydrogen atom, and m represents O or 1). Focusing on the charge transport layer of an electrophotographic photoreceptor formed by laminating the above, and as a result of intensive study to eliminate the above-mentioned drawbacks, it was found that the charge transport layer contains the above general formula (1) and the general formula (1). It has been found that by containing the compound shown above, it is possible to obtain an electrophotographic photoreceptor with no delay in the rise of the 4-position charge after repeated use, and has completed the present invention.

The present invention will be described below with reference to one drawing.

FIG. 1 is a cross-sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention, in which a charge-generating Ji 13.
Next, a charge transport M14 is provided.

FIG. 2 is a sectional view showing another configuration example of the present invention, in which an intermediate layer 12 is provided between the conductive substrate 11 and the charge generation layer 13.

3 and 4 are sectional views showing still another example of the structure of the present invention, in which a charge transport layer 14 is first placed on a conductive substrate 11.
Then, a charge generation layer 13 was provided thereon.

The conductive substrate 11 may be a material exhibiting conductivity with a volume resistance of 1010 Ωcm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, or platinum, or a metal oxide such as tin oxide or indium oxide. , film-like or cylindrical plastic, paper, etc. coated by vapor deposition or sputtering, or plates of aluminum, aluminum alloy, nickel, stainless steel, etc., and their coatings; 1. ．． 1.1. It is possible to use pipes that have been made into blank pipes by methods such as , extrusion, and drawing, and then surface-treated by cutting, superfinishing, polishing, and the like.

Next, the charge generation layer 13 will be explained.

The charge generation layer 13 is a layer containing a charge generation substance as a main material.
A binder resin may be used if necessary.

Binder resins include polyamide, polyurethane,
Polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone,
Polystyrene, polyN-vinylcarbazole, polyacrylamide, etc. are used.

Examples of charge-generating substances include CI Pigment Blue 25 (Color Index (CI) 21180).

CI Pigment Red 41 (CI 21200),
C.I. Acid Red 52 (CI 45100), C.I. Basic Red 3 (CI 4521.0), as well as phthalocyanine pigments having a porphyrin skeleton, azulenium salt pigments, squalic salt pigments, and azo pigments having a carbazole skeleton (Japanese Patent Application Laid-open No. 1983-1999- 95033), an azo pigment having a stilstilbene skeleton (described in JP-A No. 53-138229), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132)
547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Azo pigments having an oxadiazole skeleton
12742), an azo pigment having a fluorenone skeleton (described in JP-A No. 54-22834), an azo pigment having a bisstilbene skeleton (described in JP-A-54-17)
733), azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-2129),
(described in JP-A No. 54-17734), triazo pigments having a carbazole skeleton (described in JP-A-57-195767)
Publication No. 57-195768), and CI Pigment Blue 16 (CI 74100).
), C.I. Butt Brown 5 (CI 73410), C.I. Butt Dye (CI
73030), Argo Scarlet B (manufactured by Violet Co., Ltd.), Indus Thread Scarlet R
Organic pigments such as perylene pigments such as (manufactured by Bayer) can be used.

Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, disazo pigments and trisazo pigments shown below are most preferred.

Specific examples of azo pigments are shown below.

``Face''[Sumiichiichi'' Lm- These charge generating substances may be used alone or in combination of two or more.

The binder resin is suitably used in an amount of 0 to 100 parts by weight, preferably 0 to 100 parts by weight, based on 100 parts by weight of the charge generating substance.
~50 parts by weight.

The charge generation layer contains a charge generation substance, along with a binder resin if necessary, tetrahydrofuran, cyclohexanone,
It can be formed by dispersing using a ball mill, attritor, sand mill, etc. using a solvent such as dioxane or dichloroethane, diluting the dispersion liquid appropriately, and applying the dispersion. Coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer is suitably about 0.01 to 5 .mu.m, preferably 0.1 to 2 .mu.I.

The charge transport layer 14 is made of a compound (charge transport material) represented by the general formula (1) or the general formula (II) and a binder resin used as necessary.

The charge transport layer 14 can be formed by dissolving or dispersing the above-mentioned substances in a suitable solvent, applying the solution and drying it.

Representative examples of the compounds represented by general formula (1) and general formula (II) used in the present invention are illustrated below.

The above general formula (1) and general formula (■) used in the present invention
The usage ratio of the compound represented by can be selected as appropriate.

In addition, these compounds have a total amount of 0 in the charge transport layer.
．． It is appropriate to use it in an amount of 1-10% by weight, preferably 0.2-6% by weight.

If the amount added is less than this, the effects of the present invention cannot be obtained,
Moreover, if the amount added is more than this, the sensitivity will decrease.

Binder resins that may be used as necessary include polystyrene, styrene-acrylonitrile copolymer,
Styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate Thermoplastic or thermosetting resins such as resins, ethyl cellulose resins, polyvinyl butyral, polyvinyl formal, polyvinyltoluene, poly-N-vinylcarbazole, acrylic resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenolic resins, alkyd resins, etc. can be mentioned.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. are used.

The appropriate thickness of the charge transport N14 is about 5 to 100 μm. Furthermore, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 14. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are. The appropriate amount to be used is O to 30 xa degrees by weight based on the binder resin.

Silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used as leveling agents, and the amount used is based on the binder resin.
Approximately 0 to 1 fold ffi% is appropriate.

Further, in the present invention, as shown in FIGS. 2 and 4, the l+l ratio between the conductive support 11 and the charge generation layer 13 is
? By providing the intermediate NI2 in the film, it is possible to further improve the effects of the present invention, and it is also possible to improve the adhesion.

The intermediate layer 12 includes Sin, AQ 20. and other inorganic materials formed by vapor deposition, sputtering, anodization, etc., polyamide resin (Japanese Unexamined Patent Application Publication No. 58-30757, Special Publication No. 58-98739), alcohol-soluble nylon resin (Japanese Unexamined Patent Application Publication No. 1983 60-196766), water-soluble polyvinyl butyral resin (JP-A-60-196766), water-soluble polyvinyl butyral resin (JP-A-60-196766);
232553), polyvinyl butyral resin (JP-A-58-106549), polyvinyl alcohol, or the like can be used.

Furthermore, a resin intermediate layer in which pigment particles such as ZnO, TiO2, ZnS, etc. are dispersed can also be used as the intermediate layer.

Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, etc. can also be used as the intermediate layer 12 of the present invention. The thickness of the intermediate layer 12 is suitably 0 to 5 μm.

In the present invention, it is also possible to further provide an insulating layer or a protective layer on the photosensitive layer.

〔effect〕

The electrophotographic photoreceptor of the present invention has the above-mentioned structure, and contains the compounds represented by the general formula (I) and the general formula (■) in the charge transport layer, so that it has high sensitivity and has a high sensitivity before exposure. It has the remarkable effect that the deterioration in chargeability due to fatigue is extremely small, and the chargeability does not deteriorate even after repeated charging and exposure.

Therefore, according to the electrophotographic photoreceptor of the present invention, it is possible to obtain a good image without a decrease in image density, unevenness in image density, or fog, and without background stains during reversal development.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 A charge generation layer coating solution having the following composition was applied onto an aluminum plate using a doctor blade, and the film thickness was 0.2 μm (after drying).
An IL load generation layer was formed.

[Charge generation layer coating liquid]

Pigment No. 7, disazo pigment 3 parts by weight cyclohexanone 300 parts by weight, was coated with charge transport layer coating liquid A having the following composition using a doctor blade to give a film thickness of 20. A charge transport layer (after drying) was formed to obtain an electrophotographic photoreceptor of the present invention. [Coating liquid A for charge transport layer] Charge transport material of structural formula (1)-1 60 parts by weight Charge transport material of structural formula (n)-i 30 parts by weight Methylene chloride 900 parts by weight Example 2 Used in Example 1 A sample was prepared in the same manner as in Example 1, except that the charge transport layer coating liquid A was replaced with the charge transport layer coating liquid 8 below.

[Coating liquid B for charge transport layer]

60 parts by weight of a charge transporting substance of structural formula (B-z) 30 parts by weight of a charge transporting substance of structural formula (II)-2 The coating liquid A for a charge transporting layer used in Example 1 was mixed with the coating liquid C for a charge transporting layer shown below. A sample was prepared in the same manner as in Example 1 except that .

[Coating liquid C for charge transport layer]

Charge transport material of structural formula (1)-1 90 parts by weight Methylene chloride 900 parts by weight Comparative Example 2 Except that the charge transport layer coating liquid A used in Example 1 was replaced with the charge transport layer coating liquid below. A sample was prepared in the same manner as in Example 1.

[Coating liquid D for charge transport layer]

Charge transport material of structural formula (I)-2: 60 parts by weight Charge transport material of structural formula: 30 parts by weight Comparative Example 1 Methylene chloride: 900 parts by weight Example 3 Coating liquid E for charge transport layer having the following composition was coated on an aluminum plate. was applied with a blade to form a charge transport layer having a thickness of 20° after drying.

[Coating liquid E for charge transport layer]

60 parts by weight of the charge transport material of the structural formula (1)-2 30 parts by weight of the charge transport material of the structural formula (II)-1 900 parts by weight of methylene chloride Next, on top of this, the charge generation layer used in Example 1 was added. An electrophotographic photoreceptor of the present invention was prepared by spraying a coating solution to form a charge generation layer having a thickness of 0.5 threshold after drying.

Example 4 A sample was prepared in the same manner as in Example 3, except that the charge transport layer coating liquid F described below was used in place of the charge transport layer coating liquid E used in Example 3.

[Coating liquid F for charge transport layer]

Charge transport material of the above structural formula (1)-1 60 parts by weight Charge transport material of the above structural formula (n)-2 30 parts by weight Methylene chloride 900 parts by weight Comparative Example 3 Coating liquid for charge transport layer used in Example 3 A sample was prepared in the same manner as in Example 3 except that the coating liquid G for charge transport layer shown below was used in place of E.

[Coating liquid G for charge transport layer]

Charge transport material of structural formula (1)-2 90 parts by weight Methylene chloride 900 parts by weight Comparative Example 4 The following charge transport layer coating liquid H was used in place of the charge transport layer coating liquid E used in Example 3. A sample was prepared in the same manner as in Example 3 except for this.

[Coating liquid H for charge transport layer]

60 parts by weight of the charge transporting material of the structural formula (1)-1 30 parts by weight of the charge transporting material of the structural formula (1)-2 1 oz part of the polycarbonate resin (Panlite C-1,400, Kanairu Kasei Co., Ltd.) (manufactured by) methylene chloride
The characteristics of the electrophotographic photoreceptor prepared in the above manner using 900 parts by weight or more were evaluated as follows using an electrostatic copying paper tester (Kawaguchi Electric Seisakusho Layer 5P-428 model).

First, corona charging at a discharge voltage of -5.5 KV (or +6.0 KV) was performed for 20 seconds, followed by dark decay for 20 seconds, and then tungsten light of 5 Qux was irradiated.

The surface potential V, e5 0.5 seconds after the start of charging at this time
(v) was measured. Next, 4, 5 Qux on this photoreceptor
The current flowing when irradiated with tungsten light is 9.6
[Adjust the discharge current of the charging machine so that it becomes μAl,
Charging and exposure were performed for several minutes. The photoreceptor fatigued in this manner was again measured in the same manner as above. , 5m was obtained. The results are shown in Table 1.

Table 1

[Brief explanation of drawings]

1 to 4 are schematic cross-sectional views of various embodiments of electrophotographic photoreceptors according to the present invention. 11... Conductive substrate I2... Intermediate layer 13... Charge generation layer 14... Charge transport layer

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer laminated on a conductive substrate, compounds represented by the following general formula (I) and general formula (II) are incorporated in the charge transport layer. An electrophotographic photoreceptor comprising: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R^1 is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and R^2, R^3, and R^4 are hydrogen atom, substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted aryl group, Ar^1 represents a substituted or unsubstituted aryl group, and Ar^2 represents a substituted or unsubstituted arylene group. Ar^1 and R^1 may jointly form a ring. n is an integer of 0 or 1. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R^5, R^6, R^7 represent hydrogen, lower alkyl group, lower alkoxy group, dialkylamino group, or halogen atom, m represents 0 or 1.)