JPH03216662A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To suppress the increase of the initial residual potential by the introduction of an under coating layer and the increase of the residual potential at the time of repetitive use by incorporating a binder, org. charge generating material and specific diphenoquinone deriv. into the under coating layer. CONSTITUTION:The binder, the org. charge generating material and the diphenoquinone deriv. expressed by formula I are incorporated into the under coating layer of the elecarophotographic sensitive body formed by successively laminating the under coating layer, the charge generating layer and a charge transfer layer on a conductive layer. In the formula, R<1> to R<4> respectively, independently denote 1 to 8C alkyl group. The increase of the initial residual potential by the introduction of the under coating layer and the increase of the residual potential at the time of repetitive use are suppressed in this way and the electrophotographic sensitive body which yields good image is obtd.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electrophotographic photoreceptor.

(Prior Art) Conventionally, in electrophotographic materials that use photoconductive substances as photosensitive materials, selenium. Inorganic conductive materials such as zinc oxide, titanium oxide, and cadmium sulfide have been used for this purpose.

but. Generally, many of these are highly toxic, and there are problems with how to dispose of them. On the other hand, photosensitive materials that use organic photoconductive compounds are generally less toxic and less transparent than those that use inorganic photoconductive compounds. Flexibility. Light weight. Recently, it has been widely studied because it is advantageous in terms of price and so on.

Among them, composite photoreceptors that separate the functions of charge generation and transport have been rapidly increasing in recent years because they can significantly improve sensitivity, which was a major drawback of conventional photoreceptors using organic photoconductive compounds. progress is being made.

however. When a charge generation layer is provided directly on a conductive layer, surface defects such as scratches and corrosion on the conductive layer are directly reflected in the image, resulting in image defects such as black dots on a white background and white spots on a solid black background. The problem is that it is easy to cause In addition, the surface charge decreases due to charge injection from the conductive layer.
In other words, various problems are likely to occur, such as a decrease in chargeability or poor adhesion between the conductive layer and the charge generation layer.

Therefore, as a measure to improve these problems, a conductive layer has traditionally been used. A method of providing an undercoat layer between the charge generation layers has been studied (Japanese Patent Application Laid-Open No. 57-90639, JP-A No. 58-86566.
(Japanese Patent Application Laid-Open No. 60-108860).

Also, to suppress the deterioration of image quality and increase in residual potential due to the introduction of a subbing layer. A system in which unique additives are added to the undercoat layer has been studied, but no system has been found that can produce sufficient effects (%KOKAI No. 51-65943, JP-A-62-
No. 272279, Japanese Patent Application Laid-open No. 62-284362, and Japanese Patent Application Laid-open No. 62-280864. Japanese Unexamined Patent Publication 1986-16
No. 5861, % Japanese Patent Publication No. 165862/1983).

(Problems to be Solved by the Invention) As mentioned above, the introduction of an undercoat layer has been considered in order to solve problems such as the occurrence of image defects, a decrease in chargeability, and poor adhesion. When a subbing layer is introduced,
Because the electrical resistance of the undercoat layer is high, when writing image information by irradiating light onto a charged photoconductor, the undercoat layer prevents the charge generated in the charge generation layer from being injected into the conductive layer. As a result, the photoreceptor potential (residual potential) increases. If the residual potential becomes large, the potential difference between the unexposed area potential and the exposed area potential becomes small, which is undesirable as it causes a decrease in image density. Moreover, this residual potential tends to further increase with repeated use. This is thought to be because uninjected charges accumulate between the charge generation layer and the undercoat layer.

The present invention suppresses the initial increase in residual potential due to the introduction of the undercoat layer, and also suppresses the increase in residual potential during repeated use. The purpose is to obtain an electrophotographic photoreceptor that gives good images.

(Means for Solving the Problems) The present invention provides an undercoating layer or a subbing layer and a charge generating layer containing an organic charge generating material and a diphenoquinone derivative represented by general formula (1). The above-mentioned problems are solved by facilitating the movement of negative charges within the pull layer and charge generation layer and promoting the injection of negative charges from the charge generation layer and undercoat layer into the conductive layer.

That is, the present invention provides an electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive layer, in which the undercoat layer contains a binder, an organic charge generation material, and a general formula +1.
The present invention relates to an electrophotographic photoreceptor containing a diphenoquinone derivative represented by 1.

R2fc4 (wherein R't 81'', R'' and R4 each independently represent an alkyl group having 1 to 8 carbon atoms) Specific examples of the di7enoquinone derivative in the present invention are shown below.

Compound (1) Compound (2) Compound (3) Compound (4) Compound (5) The diphenoquinone derivative represented by the general formula (11) in the present invention is described in the literature (Journal of Organic Synthesis, Vol. 50, p. 3927). It can be easily synthesized according to the method described in 1985)).For example, it is represented by the following general formula +II) (wherein Rl and W have the same meanings as in general formula (1)). Phenol derivative and general formula (I'll (wherein R3 and R4 are general formula +11
The phenol derivative represented by (has the same meaning as in). It can be synthesized by carrying out a condensation reaction using potassium permanganate or the like as a catalyst.

The condensation reaction can usually be carried out in a chloroform solvent. After carrying out a condensation reaction for 2 hours at the reflux temperature of chloroform, it is cooled, and potassium permanganate is precipitated and filtered, then chloroform is distilled off, and the resulting reaction mixture is repeatedly subjected to column separation and recrystallization. The target product can be isolated.

As the organic charge generating material in the present invention K, an organic pigment that generates charges is used. The organic pigments include azoxybenzene-based, 7-thalocyanine-based, perylene-based, disazo-based, trisazo-based, pyohyl-based, and polycyclic quinoline-based. Examples include organic pigments such as tondigoid, quinacridone, and methine pigments. In addition to these pigments, any organic pigment that generates a charge upon irradiation with light can be used.

The electrophotographic photoreceptor of the present invention has a subbing layer on the conductive layer. It is obtained by sequentially laminating a charge generation layer and a charge transport layer.

The conductive layer is a conductive material such as paper or plastic film subjected to conductivity treatment, a plastic film laminated with metal foil such as aluminum, or a plate or drum of conductive metal such as aluminum.

The subbing layer contains a binder. Examples of the binder include petitral resin, formal resin, polyvinyl alcohol, and polyamide resin. Examples include acrylic resin, melamine resin, penzoguanamine resin, and silicone resin.

What are the amounts of these binders and diphenoquinone derivatives used? For 100 parts by weight of binder. The diphenoquinone derivative was added to 0.
It is preferably in the range of 1 to 200 parts by weight. 1-1
More preferably, the amount is in the range of 0.00 parts by weight. If it is less than 0.1 part by weight, the desired effect of suppressing the increase in residual potential tends to be weakened, and if it exceeds 200 parts by weight, the amount of negative charge injected from the undercoat layer to the conductive layer becomes too large. , the potential of unexposed areas tends to decrease.

In addition, the organic charge-generating material used together with the binder and diphenoquinone derivative in the undercoat layer K generates charges even within the undercoat layer, thereby smoothing charge injection from the charge generation layer to the conductive layer. Even when the layer is made thicker, it plays a role in suppressing the increase in residual potential. The content of the organic charge generating material is 0.01 to 100 parts by weight per 100 parts by weight of the binder.
It is preferable to set it as a joint of the heavy part <, o. It is more preferable to range from i to 50 parts by weight. If it is less than this range, the intended effect of suppressing the increase in residual potential tends to be weakened. If the amount is too large, the pigment tends to be poorly dispersed, resulting in image defects.

The charge generation layer includes an organic charge generation material that generates charges. The charge generation layer together with the organic charge generation material is further composed of K,
It is preferable to contain a diphenoquinone derivative represented by general formula (1). Examples of the organic charge generating material include the organic pigments mentioned above.

Also, in the charge generation layer. Additives such as binders and/or plasticizers, flowability agents, and bottle hole inhibitors that are commonly used in electrophotographic photoreceptors can be included as necessary. Examples of the binder include silicone resin, polyamide resin, polyurethane resin, polymethyl methacrylate resin, polyacrylamide resin, polycarbonate resin, and polyester resin. Also. Heat and/or photocurable resins can also be used. In any case, there is no particular restriction as long as the resin is electrically insulating and can form a film under normal conditions. In the charge generating layer, the binder is preferably used in an amount of 300 parts by weight or less based on 100 parts by weight of the organic charge generating material. If it exceeds 300 parts by weight, electrophotographic properties tend to deteriorate.

Examples of plasticizers include halogenated paraffins. Dimethylnaphthalene. Examples include dibutyl phthalate.

Examples of the fluidity imparting agent include Modaflow (manufactured by Monsando Chemical Co.). Examples of pinhole suppressants include penzoin and dimethyl phthalate.

Each of these additives is added to the organic charge generating material 100.
It is preferable to use needles in an amount of 5 parts by weight or less based on the weight of the needle.

In the charge transport layer. Contains charge transporting substances.

Examples of the charge-transporting substance include 3-7-denylcarhasol, 2-phenylindole, oxadiazole, oxatriazole, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl). ) Birazoline, 2-7enyl-4-(4-diethylaminophenyl)-5-phenyloxazole. 2-(
p-dimethylamino-7enyl)-4-(p-dimethylamino)phenyl-5-(o-chlorophenyl)-1.3
Oxazole, triphenylamine, imidazole, 2
．． 7-dinitro-9-7-fluorenone, 4,7-trinitro-9-fluorenone, IJ-N-vinyl-rubazole, enamine, 1,1,4.4-tetraallyl-substituted ptadiene. Examples include hydrazone and derivatives thereof.

The charge transport layer K also contains the same binder and plasticizer as the charge generation layer. Additives such as a fluidity imparting agent and a bottle hole suppressing agent may be included as necessary.

In the charge transport layer, the binder is a charge transport material 100
It is preferable to use it in an amount of 400 parts by weight or less. If it exceeds 400 parts by weight. Electrophotographic properties tend to deteriorate. As a charge transport material, polyN-
When using only a low-molecular charge-transporting substance such as an enamine derivative, which is different from a polymeric charge-transporting substance such as vinyl rubazole, due to film characteristics. It is preferable to use 50 parts by weight or more of the binder per 100 parts by weight of the low-molecular charge transport material. It is preferable that each of the above additives is used in an amount of 5 parts by weight or less based on the charge transporting material.

The thickness of the undercoat layer is preferably from 0.01 to 30 μm, and more preferably from 0.1 to 10 μm. The thickness of the charge generation layer is preferably 0.001 to 10 μm (and more preferably 0.2 to 5 μm. The thickness of the charge transport layer is preferably 5 to 50 μm.
It is more preferable that it is 25 micrometers.

If the thickness of the undercoat layer is less than 0.01 μm, image defects such as black dots on a white background or white spots on a solid black surface are less likely to occur when an image is formed, but if it exceeds 30 μm, The residual potential becomes high. This tends to cause a decrease in image density.

The thickness of the charge generation layer is o. Below ooiμm. Sensitivity tends to be poor, and if it exceeds 10 μm, residual potential tends to increase. Furthermore, if the thickness of the charge transport layer is less than 5 μnl, the charging property tends to be poor; if it exceeds 9.50 μm, the chargeability tends to be poor. Sensitivity tends to decrease.

The above-mentioned subbing layer and charge generation layer. The charge transport layer is formed using acetone and methyl ethyl ketone as the respective layer forming components. It can be formed by uniformly dissolving or dispersing in a solvent such as tetrahydrofuran, toluene, xylene, methylene chloride, trichloroethane, etc., then coating and drying. Depending on the type of organic charge generating material used, the charge generating layer can be formed by vacuum evaporating an organic pigment without using a binder.

The electrophotographic photoreceptor according to the present invention may have a protection layer on its surface.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

Each material used below is listed below. In addition, the symbol in parentheses indicates an abbreviation.

(1) Organic charge-generating material τ-type metal-free lid cyanine (H2Pc) [Toyo Ink Manufacturing ■] (2) Charge-transporting substance p-dimethylaminobenzaldehyde diphenylhydrazone (HYZ) ・1. 1-bis(p-diethylaminophenyl)-4
,4-diphenyl-1,3-butadiene (DEAB) (3) Binder: Boryamide resin; CM800 (PAD) [manufactured by Toray ■] Q Buteral resin; Eslet/BH-3 (PVB) [
Made by Sekisui Chemical ■ Silicone resin: KR-255 (K}t-255)
[Manufactured by Shin-Etsu Chemical Co., Ltd.] ・Polycarbonate resin; Yubilon S-2 0 0
0 (S-2000) [Made by Mitsubishi Gas Chemical ■] Examples 1 to 14, Comparative Examples 1 to 8 (a) PAD 3. Og and PVB2.09 were dissolved in a mixed solvent of 459 g of toluene and 50 g of methanol. H2Pc O. 1 g was added and ultrasonic dispersion was performed for 30 minutes. The compounds shown in Table 1 (1
) to (5) above, add 0.5 g of the diphenoquinone derivative shown as a specific example of the diphenoquinone derivative represented by general formula (1), and uniformly dissolve it to form a coating liquid for the undercoat layer. Created. This coating liquid was applied onto an aluminum plate (conductive layer) using the dipping method. It was dried at 120° C. for 30 minutes to form a subbing layer with a thickness of 1 μm.

(bl then H2Pc 2.5 g, KR
2 5 55.0g and tetrahydrofuran 92. ．． 5
This mixed solution was kneaded for 8 hours using a pole mill (a 3-inch bot mill manufactured by Nihon Kagaku Togyo Co., Ltd.). This blood was applied using an applicator onto the subbing layer of the plate prepared using D(a+) and dried at 100°C for 15 minutes to form a charge generation layer with a thickness of 1 μm. When adding the same diphenoquinone derivative as in (a), add 0.5 g of the diphenoquinone derivative of the compound shown in Table 1 to the obtained pigment dispersion. Dissolve it uniformly to prepare a coating liquid for the charge generation layer. This coating liquid was applied with an applicator onto the subbing layer of the plate prepared in 9(a)!) and dried at 100° C. for 15 minutes to form a charge generation layer with a thickness of 1 μm.

(c) Next, a charge transport substance 109 of the compound shown in Table 1, S-2000 109 as a binder and methylene chloride 409 and 1, 1, 2 as a solvent
Immediately after preparation, a coating liquid for a charge transport layer containing monotrichloroethane 409 was applied onto the charge generation layer obtained in BL so that the film thickness after drying was 15 μm, and then the coating liquid was heated at 120°C.
Let it dry for 2 hours. An electrophotographic photoreceptor was manufactured by forming a charge transport layer.

The electrophotographic photoreceptor thus produced was 60 x 70-
Cut into corners. Electrostatic recording paper testing device (Kawaguchi Electric SP-4
The electrophotographic properties were measured using 28) and the results are shown in Table 1. The initial potential v0 in Table 1 is for the sample SP-4.
The charged potential is shown when corona discharge is performed for 2 seconds at a voltage of -5 kV while rotating at a speed of 1000 revolutions/minute after setting on a rotating disk of 28, and the dark decay VK is after being left in a dark place for 2 seconds. Potential decay at (Vx =
Vt/VoXIOO, Vz is the potential after being left for 2 seconds)
, and the residual potential vR after being left for 2 seconds. Illuminance 30
It shows the potential after irradiation with Lux white light for 0.2 seconds.

In addition, changes in each characteristic after repeating the above series of operations for 1000 cycles were investigated.

(Effects of the Invention) The electrophotographic photoreceptor of the present invention has a low initial residual potential (Va) and a small increase in VB even when used repeatedly.
It is an excellent product that gives a good image.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor in which a subbing layer, a charge generating layer, and a charge transporting layer are sequentially laminated on a conductive layer, wherein the subbing layer includes a binder, an organic charge generating material, and a general formula. An electrophotographic photoreceptor comprising a diphenoquinone derivative represented by (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1, R^2, R^3 and R^4 each independently represent an alkyl group having 1 to 8 carbon atoms) 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generation layer contains a diphenoquinone derivative represented by the general formula (I).