JPS63253366A - electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain the titled body which has high sensitivity and does not change the characteristics, even in the case of repeatedly using by incorporating specified hydrazone electric charge transfer substance and compd. in an electric charge transfer layer respectively. CONSTITUTION:The charge transfer layer is composed from a binder resin, the hydrazone charge transfer substance shown by formula I and the compd. shown by formula II. In formulas I and II, R<1> and R<2> are alkyl or aryl group which may be substd., A is an aromatic hydrocarbon or an aromatic heterocyclic group which may be substd., (n) is 1 or 2, R<3>-R<6> are each hydrogen atom, hydroxy, alkyl or alkoxy group, R<7> and R<8> are each hydrogen atom or alkyl group, Z is an atomic group necessary for forming a 2H-chromene nucleus, a chroman nucleus or a dihydrobenzofuran nucleus which may be substd. Thus, the titled body which has the high sensitivity, the less optical fatigue etc., and the very excellent durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an electrophotographic photoreceptor, and more particularly to a J#II type electrophotographic photoreceptor having excellent repeatability.

(a) Prior art and points of interest Conventionally, as an electrophotographic photoreceptor, a photoreceptor whose main component is an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide)f
il: The possession was widely known.

However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In addition, selenium and cadmium sulfide are particularly toxic, so there are restrictions in production and handling.

On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, easy to handle, and are generally not suitable for selenium photoreceptors. It has many advantages, such as superior thermal stability, and has attracted a lot of attention in recent years.

Poly-N
-Vinylcarbazole is well known as 2s, slender,! =
2.4.7-) An electrophotographic photoreceptor having a photosensitive layer containing as a main component a charge transfer complex formed with a Lewis acid such as dinitro-9-fluorenone is described in Japanese Patent Publication No. 10496/1983. However, this photoreceptor is not necessarily satisfactory in sensitivity, film formability, and durability.

In response, low molecular weight organic photoconductors typified by hydrazones and pyrazolines have been proposed. By combining these with appropriate binders, film forming properties have been significantly improved, but sensitivity and durability are still far from satisfactory.

For this reason, in recent years, a laminated photoreceptor has been proposed in which the carrier generation function and carrier transport function are shared by separate substances. By adopting this structure, the characteristics and sensitivity of the band 11L are greatly improved, and an azo pigment with a particularly high carrier generation ability is used in the charge generation layer, and a hydrazone-based t-carrier with a high carrier transport ability is used in the charge generation layer. By combining substances, some have appeared that have sensitivity close to that of inorganic photoreceptors such as j) and Be. As a result, the current situation is that photoreceptors containing these types of organic photoconductive compounds as main components are beginning to make significant inroads into the fields of photographic devices, printers, and the like. - This is one of the major weaknesses of this type of organic photoreceptor, which uses an azo pigment as a charge generating material and combines it with a hydrazone charge transporting material. The so-called charge-accepting photomemory phenomenon has not yet been fully determined, especially in electrophotographic processes such as copying machines.

This is a big problem in the return system. This charge-receptive photomemory phenomenon is a type of fatigue phenomenon in which the charge-receptivity of the photoreceptor changes due to physical property changes caused by light irradiation. It is reversible and can be recovered by When a photoreceptor has such properties, repetition of charging and exposure causes a decrease in initial potential and an increase in residual potential, resulting in a large gap in practical use. In addition, if such a photoreceptor is exposed to fluorescent light and then installed in a copying machine, the charging property will be significantly reduced during the normal copying process, which may impede use. It becomes a big obstacle. Furthermore, when using a photographic camera, the photoreceptor is often exposed to light inside the vehicle for a long time during work such as inspecting parts around the photoreceptor and removing paper jams.

In such a case, the same problem as above occurs.

(Q. Purpose of the Invention The purpose of the present invention is to provide an electrophotographic photoreceptor with improved optical memory phenomenon, which has high sensitivity and whose characteristics do not change even after repeated use.

(To) Structure of the Invention As a result of various studies in order to achieve the above object, the present inventors used an azo pigment as a charge generating substance and used the following general formula (I
The inventors have discovered that it is effective to include a hydrazone charge transport substance represented by the following formula (2) and a compound represented by the general formula (2) in the charge transfer layer, leading to the present invention.

That is, the present invention provides a laminated electrophotographic photoreceptor comprising a charge generation layer containing a conductive azo pigment as a charge generation substance and a charge transfer layer, the charge transfer layer comprising a binder resin, a binder resin,
The following general formula (I) (in the formula, R1 and R2 are an alkyl group or an aryl group which may have a substituent (tN), and R1 and R2 are an aromatic hydrocarbon or an aromatic hydrocarbon which may have a substituent) A hydrazone charge transport substance represented by a group heteroshelf group, n represents 1 or 2) and a compound of the following general formula (2) [wherein R1, R, and R are individually is selected from hydrogen, a hydroxyl group, an alkyl group and an alkoxy group (provided that at least one of Ra-R6 is a hydroxyl group), 几 and R are individually selected from hydrogen and an alkyl group, and 2 is substituted. 2
1] - Represents the atom number necessary to form a chromene skeleton, chromane skeleton, or dihydrobenzofuran skeleton.

] Each component of the present invention will be explained in detail below.

First, as the conductive support on which the photosensitive layer is formed, any of those employed in well-known electron triad photoreceptors can be used.

Specifically, for example, a metal drum made of aluminum, copper, etc.
Examples of the sheet include laminates and vapor deposits of these metal foils.

Further examples include plastic films, plastic drums, paper, etc. which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder to conductivity treatment.

Other examples include plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

Is the charge generation layer an azo pigment? Preferably, it can be provided by dispersing and coating in a washing medium together with a binder.

Specifically, the azo pigments used include, for example, an azo pigment having a carbazole bone core (described in Japanese Patent Publication No. 53-95033), an azo pigment having a sunaryl stilpene bone core (described in Japanese Patent Publication No. 1983-133229), (described in Japanese Patent Application Laid-open No. 1983-132), an azo pigment that supports triphenylamine bone core (JP-A-53-132)
547), an azo pigment having a dibenzothiophene bone core (described in JP-A-54-21723),
Azo pigment with oxadiazole core (% opening 54-
12742), an azo pigment having a fluorenone bone core (Japanese Unexamined Patent Publication No. 54-22834), an azo pigment having a bisstilbene core (Japanese Unexamined Patent Publication No. 54-17733)
(described in Japanese Patent Publication No. 54-2129), an azo pigment having a distyryloxadiazole bone core (described in Japanese Patent Publication No. 54-2129),
Azo pigments having distyrylcarbazole bone cores (described in % JP-A No. 54-17734), trisazo pigments having carbazole bone cores (described in JP-A-57-195767 and JP-A-57-195768) etc. can be opened.

Examples of binders include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic esters, and methacrylic esters, phenoxy resins, polysulfones, arylate resins, and polycarbohydrates.4. ．． -), polyester, cellulose ester, cellulose ether, urethane resin, epoxy resin, acrylic polyol addition, and other taniyu polymers.

Examples of solvents include ethers such as tetrahydrofuran and l,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide, acetonitrile, N-methylpyrrolidone, and dimethyl sulfoxide. alcohols such as methanol, ethanol, and impropatol; esters such as ethyl acetate, methyl acetate, and methyl cellosolve acetate; and chlorinated hydrocarbons such as dichloroethane and chloroform.

The thickness of the charge generation layer is preferably about 0.1 to 2 seconds.

The charge transport layer can be provided by dissolving a binder, a hydranone charge transport substance of the general formula (!), and a compound represented by the general formula (2) in an appropriate solvent, and applying the solution.

As binders, polymers and copolymers of vinylated adducts such as styrene, vinyl chloride, acrylic esters, methacrylic esters, and vinyl acetate, phenoxy resins, polysulfones, polycarbonates, polyarylates, polyesters, cellulose esters, cellulose ethers, Examples include urethane resin, epoxy resin, and silicone resin.

As a solvent, tetrahydrofuran, methyl ethyl ketone, benzene, toluene, monochlorobenzene, 1,2-
Dichloroethane, ethyl acetate, etc. are used.

Specific examples of the hydrazone charge transport substance represented by the general formula (!) include, but are not limited to, 0(I-1) (I-2) CI- 3) (I-5) t Specific examples of the compound represented by the general formula (6) include, but are not limited to, the following.

(II-1) (n-2) (n-3) e <ll-4) (ns) e (II-6) e (...-9) M. of the compound represented by general formula (6) The amount added is 0.01 to 50 parts by weight, preferably 0.05 to 20 parts by weight, per 100 parts by weight of the charge transport material of general formula α). The thickness of the charge transfer layer is preferably about 5 to 100 μm. The photosensitive layer of the electrophotographic photoreceptor of the present invention contains a known additive to improve film formability, flexibility, and mechanical strength. Good too. Examples of roughening agents include aromatic compounds such as heptalic acid esters, sicic acid esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and methylnaphthalene. It goes without saying that it may have an intermediate layer and a transparent insulating layer. Example 1 The azo compound 0.2Ii represented by the following structural formula (10), the polyarylate (U-100 manufactured by Unitika) 0.2N, and a total of 1. In addition to 2-dichloroethane 20-, it was dispersed for 2 hours with a paint conditioner.The obtained dispersion was applied onto an aluminum plate so that the film thickness after drying was 0.5 μm and dried to generate a charge. Layer?formed.

Furthermore, 12I of hydrazone of Exemplified Compound (I-1), 12I of polyarylate (U-100 manufactured by Unitika) and 0.211 of Exemplified Compound (n-2) were added to 120% of chlorobenzene.
An electrophotographic photoreceptor of the present invention was prepared by applying and drying a solution containing IiK to a film thickness of 12A after drying to form a charge transfer m layer.

The photoreceptor was stored day and night at a room temperature of 30° C. in a dark place, and then mounted on an electrostatic paper tester "5p-428J (manufactured by Kawaguchi Denki Seisakusho), and the following characteristic tests were conducted.

That is, the voltage of the charger 6 was charged, and then the sample was left in the dark for 10 seconds, and the potential Vo (-V) at that time was determined. Next, light from a halogen lamp was irradiated with a light intensity of 301 uz on the surface of the photosensitive layer, and the amount of exposure (1 ux·sec) required to significantly attenuate the surface potential of the photosensitive layer was determined. Furthermore, using the same light source, the total surface potential is 5.
The exposure amount B116 (lu
x seconds) was calculated. Next, this photoreceptor ft5000
After exposing it to the light of a fluorescent lamp with an illuminance of lux for 5 minutes and leaving it in a dark place for 30 seconds, a characteristic test M similar to the above was performed and the charging potential Vo (-V), E H (lugs seconds), Eso
(luzs seconds) was calculated. The results are shown in Table 1.

A photoreceptor was prepared in the same manner as in Example 1, except that the azo compound (Supplementary Table 1, Comparative Example 1, Exemplified Compound (n-2) 't'' was not added, and a characteristic test was conducted. The results are shown in Table 2. .

Table 2 Example 2-8 and Comparative Example 2-5 A photoreceptor was prepared in the same manner as in Example 1 using the azo compound shown in Table 3, the hydrazone of general formula (I), and the exemplary compound of general formula (2). Then, a characteristic test was conducted.

In addition, a similar photoreceptor was prepared as a comparative example, except that the exemplified compound of general formula (6) was not included on the valley side. The results are shown in Table 3.

Y: Comparative Example 6-9 A photoreceptor similar to Example 1 was prepared except that Comparative Compound VI or (2) below was used in place of Exemplified Compound n-2. In addition, in Example 2, exemplified compound n
A similar photoreceptor was prepared except that Comparative Compound (1) or (2) below was used in place of -1. Characteristic tests were conducted on these photoreceptors, and the results are shown in Table 4.

(G) Effects of the Invention The photoreceptor obtained according to the present invention is of #I type and has low durability and low durability.

Claims (1)

[Claims] (1) Consisting of a conductive layer, a charge generation layer containing an azo pigment as a charge generation substance, and a charge transfer layer, the charge transfer layer is a binder resin and has the following general formula (I) ▲Mathematical formula, chemical formula, table, etc.▼ ( In the formula, R^1 and R^2 represent an optionally substituted alkyl group or an aryl group, and A represents an optionally substituted aromatic hydrocarbon or aromatic heterocyclic group. 1. A laminated electrophotographic photoreceptor comprising a hydrazone charge transport material represented by the following formula (wherein n represents 1 or 2) and a compound represented by the following general formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R^3, R^4, R^5, R^6 are individually hydrogen,
selected from hydroxyl group, alkyl group and alkoxy group (provided that at least one of R^3 to R^6 is a hydroxyl group), R^7 and R^8 are individually hydrogen,
and an alkyl group, and Z represents an atomic group necessary to form an optionally substituted H-chromene skeleton, chromane skeleton, or dihydrobenzofuran skeleton. ]