JPH0629974B2 - Electrophotographic photoconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more specifically, to a charge generating layer of an electrophotographic photoreceptor in which a charge generating layer and a charge transport layer are sequentially laminated on a conductive support. Regarding

2. Description of the Related Art A so-called charge generation layer capable of generating charge carriers by absorbing light is provided on a conductive support, and further, a so-called charge generation layer is provided thereon.
There have been proposed a large number of function-separated laminated electrophotographic photoconductors provided with a so-called charge carrier layer capable of moving charge carriers generated in the charge generation layer by the force of an electric field.

In these laminated electrophotographic photoreceptors, the charge generation layer is generally 1) vacuum-deposited, glow discharge, etc. on a charge generation substance such as Se, Se alloy, a-Si (amorphous silicon), and organic pigment. 2) Se, Se alloy, ZnO, TiO ₂ , an inorganic pigment such as CdS, and a charge generating substance such as an organic pigment, are provided by the following (for example, disclosed in JP-A-48-47838 and JP-A-49-48334): If necessary, a binder is added and the resulting dispersion is applied (for example, JP-A-47-18543 and JP-A-55-55).
-79449, etc.) 3) Applying a solution in which a charge generating substance of an organic pigment is dissolved in an organic amine (for example, described in JP-A-52-55643) on a conductive support. It is provided in.

On the other hand, the charge transport layer is generally provided by dissolving a charge transport substance together with a binder in a solvent and applying the solution by a suitable coating method.

The thus obtained laminated type electrophotographic photoreceptor has the electric functions basically required for the photoreceptor, namely, generation of charge carriers by light absorption, retention of charge by charging and transfer of generated charge, respectively. Separated into a layer and a charge transport layer.

Here, the charge carriers generated in the charge generation layer are injected into the charge transfer layer by the force of the electric field, but when the matching of the energy levels of the charge generation layer and the charge transfer layer is insufficient, or during use. When the energy level changes due to the deterioration of, a potential that is not attenuated by light irradiation, that is, a residual potential occurs, and when the residual potential increases by repeated use, a phenomenon occurs. The increase in the residual potential is a constraint on the usage conditions of the copying machine and is a major factor in determining the life of the photoconductor.

Therefore, various measures have been taken in order to suppress the rise in the residual potential. For example, (1) it has been proposed to measure the energy level matching by combining a specific charge generation layer and a specific charge transport layer from various materials. However, although it is certainly sufficient for use in a limited range, under severe conditions of use, deterioration is unavoidable, which leads to an increase in residual potential. It will be limited. Further, (2) it has been proposed to allow an electron accepting substance or an electron donating substance to be present in the charge transport layer to form a charge transfer complex with the charge transport substance (for example, JP-A-54-10738, 54-158928 and other publications). Although this method is also effective in suppressing the increase in residual potential, the light transmittance of the charge transport layer is lowered due to the formation of the charge transfer complex, and the sensitivity is lowered.

OBJECT The object of the present invention is to provide a laminated electrophotographic photoreceptor in which the rise in residual potential can be suppressed without degrading the sensitivity.

Structure The present invention is a laminated electrophotographic photoreceptor, Pd, Ag, Fe, Ti, Cu, In, Sn, Al in the charge generation layer containing a photoconductive organic pigment.
It is characterized by containing a powder of a metal selected from the group consisting of:

By the way, the inventors of the present invention suppress the rise in residual potential, and as a result of various studies, they found that the presence of a specific metal material in the form of powder in the charge generation layer suppressed the rise in residual potential. It was The present invention has been completed based on such findings.

The specific metal material is a metal composed of Pd, Ag, Fe, Ti, Cu, In, Sn, and Al and has a contact potential difference of 1000 mV or less with Au.
The reason why the increase in residual potential is suppressed when the powder of such a specific metal material is contained in the charge generation layer is unknown in detail, but the contact potential difference with Au is
When a metal material of 100 mV or less is present in the charge generation layer, the charge is easily injected from the metal material due to contact with the charge generation layer forming substance, and the charge is captured in the photosensitive layer to give a residual potential. It is thought that this is to neutralize the charge.

By the way, conventionally, the standard of easiness of electron emission in a metal material or the like is expressed by a work function, and its value is presented in various documents, but in reality, it is extremely difficult to directly measure the work function. Therefore, the present inventors set a standard for the ease of electron emission of various metal materials by the contact potential difference with Au, select a metal material having a contact potential difference of a specific value, and make it exist in a powder form in the charge generation layer. This confirmed that the increase in residual potential was suppressed.

The contact potential difference with respect to Au can be easily obtained by using a commercially available low level surface electrometer. Table-1
An example of measurement is shown in.

Next, a method for producing the laminated electrophotographic photoreceptor according to the present invention will be described.

The laminated electrophotographic photoreceptor of the present invention is basically made of aluminum, nickel, chromium, tin oxide, indium oxide, etc., which are polyester film, polypropylene film,
Conductive treated by vapor deposition on a plastic film such as cellulose acetate film, or a metal plate or metal tube of aluminum, nickel, iron, etc. as a conductive support, on which a charge generation layer is provided, and a charge transfer layer is further laminated. It is obtained by doing.

The charge generation layer of the present invention comprises a photoconductive organic pigment such as CI Pigment Blue 25 [color index (C
I) 21180)], CI Pigment Red 41 (CI2120)
0), CI GLAZIDE 52 (CI45100), CI BASKETLE GLEED 3 (CI45210), and an azo pigment having a carbazole skeleton (described in JP-A-53-95033),
Azo pigment having styrylstilbene skeleton (Japanese Patent Application Laid-Open No. 53-1
38229), an azo pigment having a triphenylamine bone nucleus (described in JP-A-53-132547), and an azo pigment having a dibenzothiophene bone nucleus (described in JP-A-54-21728). , Azo pigments having oxadiazole skeleton (described in JP-A-54-12742), azo pigments having fluorenone skeleton (described in JP-A-54-22834), azo having bisstilbene skeleton Pigments (described in JP-A-54-17733), azo pigments having distyryl oxadiazole bone nuclei (described in JP-A-54-2129), azo pigments having distyryl carbazole bone nuclei (JP-A-54 No. 54-17734), trisazo pigments having a carbazole bone nucleus (described in JP-A Nos. 57-195767 and 57-195768), and CI Pigment Blue 16 (CI741).
00) and other phthalocyanine pigments, CI Aibut Brown 5 (CI73410), CI Aibutto Dye (CI73030) and other indigo pigments, Argos Carrett B (Biorett Co.), Indanthren Scarlett R (Bayer Co.)
Perylene pigments, such as
Pd, Ag, Fe, T, which are metals whose contact potential difference with Au is 1000 mV or less
It is possible to add powders of i, Cu, In and Sn, and further to disperse them in a solvent together with a binder, if necessary, and provide them by a known coating method.

The amount of these metal materials added is 50% by weight or less, preferably 10% by weight or less, based on the photoconductive organic pigment. The powder of the metal material preferably has a particle size of 1000Å or less.

As the binder, polyvinyl butyral resin, polyvinyl formal resin, acrylic resin, polyester resin, polycarbonate resin, phenoxy resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, polyamide resin, polyurethane resin, various cellulose resins, etc. are used. You can do it. The amount of the binder with respect to the photoconductive organic pigment is appropriately 0 to 200% by weight.

Examples of the solvent include benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, methyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, dimethylformamide, cyclohexanone, methyl cellosolve, ethyl cellosolve, and mixtures thereof. Is mentioned.

The thickness of the charge generation layer is 0.05 to 2 μ, preferably 0.1 to 2 μ.
The degree is appropriate.

On the other hand, the charge carrier layer is provided by dissolving the charge carrier substance in a solvent together with a binder and applying the solution.

The charge-carrying substance may be one used in conventional laminated electrophotographic photoreceptors, for example, poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate. And its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styryl. Anthracene, styrylpyrazoline, phenylhydrazones, α
An electron-donating substance such as a stilbene derivative, or a fluorenone derivative, a dibenzothiophenene derivative, an indenothiophenene derivative, a phenanthrenequinone derivative, an indenopyridine derivative, a thioxanthone derivative, a benzo [ε] cinnoline derivative, a phenazine oxide derivative , Electron-accepting substances such as tetracyanoethylene, tetracyanoquinodimethine, bromanil, chloranil, and benzoquinone.

The charge transport layer includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer,
Styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyarylate resin, polyvinylidene chloride, cellulose acetate, cetyl cellulose, polyvinyl butyral, polyvinyl formal, polyamide, Poly-
Natural substances such as N-vinylcarbazole, polyvinyltoluene, acrylic resin, polycarbonate, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin and other thermoplastic resins, thermosetting resins, starch, glue, casein, etc. , Alone or mixed as a binder, and if necessary known plasticizers, leveling, etc. are added, dissolved in a solvent such as tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, and applied on the charge generation layer. It is provided by doing. A suitable thickness of the charge transport layer is about 5 to 100 μm.

In the present invention, in order to improve the interlayer adhesion and charging characteristics of the photoreceptor, before forming the charge generation layer, an adhesive layer of polyamide, polyvinyl acetate, polyurethane or the like on the conductive support or aluminum oxide or the like. A thin layer of
It can be provided to a thickness of about 0.01 to 2.0 μm by a conventional method such as vapor deposition.

Example-1 Disazo pigment having the following structural formula 5% by weight of polyvinyl butyral resin (XYHL, UCC)
Tetrahydrofuran solution
13.6g Ultrafine iron powder (manufactured by Vacuum Metallurgy Co., Ltd., particle size 300Å) 0.017g Tetrahydrofuran 44.2g was dispersed in a glass ball mill (10mmφ agate ball member) for 48 hours, and then tetrahydrofuran 22.3g.
g and 37.2 g of ethyl cellosolve were added and dispersed for 1 hour.
After the dispersion, the mill base was taken out into a container, and tetrahydrofuran and ethyl cellosolve were diluted and stirred at a weight ratio of 4: 6 and a solid content concentration of 1% by weight to prepare a dispersion liquid for coating. This dispersion was applied on an Al vapor-deposited polyester film with a doctor blade and dried to form a charge generation layer having a thickness of 0.5 μm.

Further, a coating solution for forming a charge transport layer having the following composition is prepared, and the charge generation layer is coated with a doctor blade, and a charge transport layer having a thickness of 20 μm after drying is provided to provide a laminated electrophotographic film. A photoconductor was created.

Hydrazone compound with the following structural formula Polycarbonate resin 20g (K-1300 manufactured by Teijin Chemicals Ltd.) Silicon oil 0.002g (KF50 manufactured by Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran 160g Comparative Example-1 Except for using the charge generation layer forming coating liquid excluding ultrafine iron powder. A laminated electrophotographic photoreceptor was prepared using the same materials and conditions as in the examples.

Next, each of the above-mentioned two types of photoconductors was charged by applying a corona discharge of -6 KV for 20 seconds using a commercially available electrostatic copying paper tester, and the surface potential Vs (volt) at that time was measured, followed by darkness. After leaving it for 20 seconds, measure the surface potential Vo (volt) at that time, and then illuminate it with 20 lux white tungsten light to reduce Vo to 1/10.
(Lux.sec) and the surface potential V _D30 after 30 seconds of irradiation were measured. This operation, that is, charging 20 seconds, dark decay 20 seconds, light irradiation 30 seconds, is repeated 10 times, and again Vs, Vo, E1 / 2
And V _D30 were measured. The above results are shown in Table 2.

Example-2 0.017 g of the ultrafine iron powder of Example-1 is replaced with 0.034 g of ultrafine iron powder.
A laminated electrophotographic photoreceptor was prepared by using the same materials and conditions as in Example 1 except that the particle size was changed to 1000Å.

Example-3 A multilayer electrophotographic photoreceptor was prepared with the same materials and conditions as in Example-1, except that 0.017 g of ultrafine iron powder of Example-1 was replaced with 0.017 g of ultrafine iron powder (particle size 1000Å). Created.

Example-4 0.017 g of the ultrafine iron powder of Example-1 was replaced with 0.05 g of ultrafine aluminum powder.
A laminated electrophotographic photoconductor was prepared using the same materials and conditions as in Example 1 except that the amount was changed to 34 g (particle size 1000 Å).

Comparative Example-2 0.017 g of the ultrafine iron powder of Example-1 was added to 0.034 g of magnesium fine powder.
Example-1 except that g (300 mesh powder) was changed.
A laminated type electrophotographic photosensitive member was prepared by using the same materials and conditions as described above.

The contact potential difference between magnesium and Au is 1100 to 15
It is 00 mV.

The examples of the photoreceptors of these examples and comparative examples are also-
Vs, Vo, E1 / 2 and V _D30 were measured in the same manner as in 1 and Comparative Example-1. The above results are shown in Table-3.

Effect As can be seen from the results in Tables 2 and 3, the laminated electrophotographic photosensitive member according to the present invention shows no increase in residual potential and is faster in sensitivity than the conventional one (Comparative Example).

Claims (1)

[Claims] 1. A laminated electrophotographic photosensitive member comprising a conductive support, on which a charge generation layer containing a photoconductive organic pigment and a charge transport layer are sequentially provided, wherein Pd, Ag, Fe, Ti, Cu, I
An electrophotographic photoreceptor comprising a metal powder selected from the group consisting of n, Sn, and Al.