JPS60214364A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To suppress rise of residual potential as low as possible and to improve sensitivity by incorporating a metallic powder having a potential difference of <=1,000mV in contact with gold in an electrostatic charge generating layer. CONSTITUTION:Metallic materials having potential difference of <=1,000mV in contact with Au are powders of Pd, Ag, Fe, Ti, Cu, In, Sn, etc., and preferable particle diameters are <=100nm. A 500nm thick charge generating layer is formed on a polyester film coated with a vapor-deposited Al film by dispersing a disazo pigment represented by formula I , a polyvinylbutyral resin, and an ultrafine iron powder having <=30nm particle diameter into tetrahydrofuran in a ball mill for 48hr, then, adding tetrahydrofuran and ethyl cellosolve, further dispersing them for one hr, taking the dispersion out of the mill into a vessel, diluting and stirring it, and finally coating the film with this dispersion and drying it. A charge transfer layer having a dry film thickness of 20mum is formed on said charge generating layer by coating it with a coating fluid composed of a hydrazone compd. of structural formula II, a polycarbonate resin, a silicone oil, and tetrahydrofuran.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a photoreceptor for electrophotography, and more specifically, a charge generation layer of a photoreceptor for electrophotography, in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support. Regarding.

PRIOR ART A so-called charge generation layer capable of generating a stain carrier by light absorption is provided on a conductive support, and furthermore, on top of that,
Many functionally separated laminated type electrophotographic photoreceptors have been proposed that are provided with a so-called charge transport layer in which charge carriers generated in a charge generation layer can be moved by the force of an electric field.

In these laminated electrophotographic photoreceptors, the charge generation layer is generally formed by 1) providing a charge generation substance such as a Bes Se alloy, a-st (amorphous silicon), or an organic pigment by vacuum evaporation, glow discharge, or the like; (For example, described in JP-A-48-47838 and JP-A-49-48334) 2) Be, 8e alloy, Zn (L Ti01 , OdS
A dispersion of charge-generating substances such as inorganic pigments and organic pigments, with the addition of a binder if necessary, is coated (for example, as disclosed in Publications such as 18543-18543 and 79449-55). 3) Applying a solution of an organic pigment charge-generating substance dissolved in an organic amine (for example, JP-A No. 52
(described in Japanese Patent No. 55643).

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

The laminated electrophotographic photoreceptor obtained in this way performs the electrical functions fundamentally required of a photoreceptor, that is, charge carrier generation by light absorption, charge retention by charging, and charge generation. It is separated into a charge transport layer.

Here, the charge carriers generated in the charge generation layer are injected into the charge transport layer by the force of the electric field, but if the energy levels of the charge generation layer and the charge transport layer are insufficiently matched, When the energy level changes due to deterioration during use, a phenomenon occurs in which a potential that does not attenuate even with light irradiation, that is, a residual potential is generated, and the residual potential increases with repeated use. The increase in residual potential limits the usage conditions of copying machines and is a major factor in determining the lifespan of the photoreceptor.

Therefore, various measures have been taken to suppress the increase in residual potential. For example, (1) it has been proposed to match energy levels by combining a specific charge generation layer and a specific charge transport layer from various materials. However, although this is certainly sufficient for use within a certain limited range, 1 Under harsh usage conditions, deterioration is inevitable, leading to an increase in residual potential, and the above-mentioned range of interest rate selection is unavoidable. will also be limited. Furthermore, it has been proposed that (2) an electron-accepting substance or an electron-donating substance be present in the charge-transporting layer 11 to form a charge-transfer complex with the charge-transporting substance (for example, JP-A-54-10738 , 54-158
(described in publications such as 928). Although this method is effective in suppressing the increase in residual potential, the light transmittance of the charge transport layer decreases due to the formation of a charge transfer complex, resulting in a decrease in sensitivity.

The present invention is a laminated electrophotographic photoreceptor characterized in that the charge generation layer contains powder of a metal material having a contact potential difference with respect to Au of less than 1000 In.

By the way, in order to prevent the remaining 11 from ascending the throne,
As a result of various studies, it has been found that the increase in residual potential can be suppressed by making a specific metal material exist in powder form during the charge generation process. The present invention was completed based on this knowledge.

A specific metal material has a contact potential difference of 10100 with Au.
It is below O. The reason why the increase in residual potential is suppressed when powder of such a specific metal material is included in the charge generation layer is not known in detail, but when the contact potential difference with Au is 10,100 O or less, When a metal material is present in the charge generation layer, upon contact with the charge generation layer forming substance, charges are easily injected from the metal particles, and the charges are captured in the photosensitive layer and become a residual potential. It is thought that the purpose is not to neutralize the

Conventionally, the ease with which electrons can emit electrons in metal materials, etc., has been expressed as a work function, and various documents have presented this value, but in reality, it is extremely difficult to directly measure the work function. difficult.

Therefore, the present inventors selected a metal paulownia material having a specific value of contact potential difference, taking into account the contact potential difference with Au and the ease of electron emission of various metal particles, and added powder to the charge generation layer. It has been confirmed that the increase in residual potential can be suppressed by making it exist in the form of 0. The contact potential difference can be easily set by using a commercially available low-level surface potential.

Table 1 shows measurement examples.

Table 1 Note: Using 5SVII-10 manufactured by Kawaguchi Electric Co., Ltd. Next, a method for producing a laminated electrophotographic photoreceptor according to the present invention will be described.

The laminated electrophotographic photoreceptor of the present invention basically contains aluminum, nickel, chromium, tin oxide, indium oxide, etc., in polyester film, polypropylene film,
A conductive support is a plastic film such as cellulose acetate film that has been vapor-deposited and conductively treated, or a metal plate or tube made of aluminum, nickel, iron, etc., a charge generation layer is provided thereon, and a charge transport layer is laminated thereon. You can get it by doing this.

The charge generating layer of the present invention contains a photoconductive organic pigment such as C.I. Pigment Blue 25 [Color Index (OI)].
)21180)), C.I. Pigment Red 41 (
OI21200), Sea Eyed Red 52 (OI
45100), C.I. Basic Red 3 (OI4
5210), an azo pigment having a carnozole bone core (described in JP-A-53-95033), an azo pigment having a styrylstilbene bone core (JP-A-53-1382)
29), an azo pigment having a triphenylamine bone core (described in JP-A-53-132547),
Azo pigment with dipenzothiophene core
-21728), azo pigments with oxadiazole bone cores (described in JP-A-54-12742), azo pigments with fluorenone bone cores (described in JP-A-54-12742),
22834), bisstyl (azo pigment having a bone core (described in JP-A-54-17733),
Azo pigments having distyryloxadiazole bone cores (described in JP-A No. 54-2129), azo pigments having distyrylcarnozole bone cores (described in JP-A-54-1773)
4), trisazo pigments with Cal/Mazole bone cores (JP-A-57-195767, JP-A-57-1957-
7 talocyanine pigments such as CI Pigment Blue 16 (OI74100), CI Pigment Brown 5 (OI734), etc.
10), Indigo pigments such as C-I-Not-Dye (OI73030), Harilene pigments such as Argo Scarlet B (manufactured by Noiolet Co., Ltd.), Indance Scarlet B (manufactured by Inil Co., Ltd.), etc., are used alone or in combination, Metal material with a contact potential difference of 10100 O or less with Au, for example, Pd yAg * Fe l Tl tOu
+In, 8n, etc. powder can be added thereto, and if necessary, it can be dispersed in a solvent together with a binder, and can be provided 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. In addition, the powder of the metal material preferably has a particle size of 1000X or less. As the binder, polyvinyl butyl 4m 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. can be used. The amount of binder relative to the photoconductive organic pigment is suitably from 0 to 200% by weight.

Solvents include 4-benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, methyl acetate, butyl acetate, methyl ethyl ketone, dioxane, dihydrofuran, dimethylformamide, cyclohexanone, methyl cellosolve, ethyl cellosolve, etc. Mixtures thereof may be mentioned.

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

On the other hand, the charge transport layer is formed by dissolving a charge transport material together with a binder in a solvent and applying the resulting solution.

The charge transporting substance may be one used in conventional laminated electrophotographic photoreceptors, such as poly N-vinylcarnozole and its derivatives, poly r-cal/mazolylethylglutamate and its derivatives, pyrene-formaldehyde condensation. compounds and their derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9-(p-diethylaminostyryl)anthracene, 1,1-bis(
Electron-donating substances such as 4-dibenzylaminophenyl)furopane, styryl anthracene, styryl pyrazoline, phenylhytodicines, α-stilbene derivatives, or fluorenone derivatives, dipenzothiophene derivatives, indenothiophene derivatives, phenanth lenquinone derivatives,
Examples include electron-accepting substances such as indenopyridine derivatives, thioxanthone derivatives, benzo[6]dipenzone derivatives, phenazine oxide derivatives, tetracyanoethylene, tetracyanoquinodimethine, chloranil, chloranil, and benzoquinone.

The charge transport layer is made of 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, ethyl cellulose, polyvinyl butyral, polyvinyl formal, polyamide, poly N
-Vinylcarnozole, polyvinyltoluene, acrylic resin, polycar, ]? Thermoplastic resins such as esters, silicone resins, epoxy resins, melamine resins, urethane fat-savings, phenolic resins, and alkyd resins, thermosetting resins, and natural substances such as starch, glue, and casein are added as binders, either singly or in combination. If necessary, a known plasticizer, leveling agent, etc. may be added, and the resulting solution may be dissolved in a solvent such as tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc., and coated on the charge generation layer. The thickness of the charge transport layer is 5 to ioo
About μ is appropriate.

In the present invention, in order to improve the interlayer adhesion and charging characteristics of the photoreceptor, an adhesive layer of polyamide, vinyl acetate, polyurethane or the like is coated on the conductive support before forming the IB charge generating Pzt 1FC. 0.01 to 2.04 by applying a thin layer of aluminum oxide, etc., or by conventional methods such as vapor deposition.
It can be provided at about m7.

Example Disazo pigment having the following structural formula C1H @ 1.717 Ultrafine powder 65
) 0.017 g of tetrahydrofuran 442I into glass P! After dispersing for 48 hours in a tea mill (part: IQfiψ agate steel),
2.37i', add 372g of ethyl cellosolve, 1
Spread out time. After dispersion, take out the mill base into a container, and mix tetrahydrofuran and ethyl cellosolve in a weight/ht ratio of 4:
6. Dilute and stir so that the solid content concentration is 1% by weight, and gl! the dispersion for coating! Made by i. This dispersion was coated on an AJ vapor-deposited polyester film using a turret blade and dried to form a charge generation layer with a thickness of 0.5 μm.

Furthermore, a coating liquid for forming a transport layer having the following composition was prepared,
A laminated electrophotographic photoreceptor was prepared by applying a 105 charge transport layer on the charge generation layer described above using a doctor blade and having a film thickness of 20 μm after drying.

A hydrazone compound with the following structural formula, Tetrahydronerane 160# Comparative Example A laminated electronic photoprinter (for use) was prepared using the same materials and conditions as in the Example, except that the coating liquid for forming the charge generation layer was free of ultrafine iron powder. A photoreceptor was created.

Next, each of the above two types of photoreceptors was charged by applying a corona discharge of 16 KV for 20 seconds using a commercially available electrostatic copying paper tester, and the surface potential Va(d) at that time was measured. Continue to leave it in a dark place for 20 seconds, and then check the surface potential V
After measuring o(&lt), the exposure i E required to attenuate Vo to 1/10 by irradiating 20 lux white tungsten light E 1/10 (lux seconds) and irradiation 30
The surface potential VDgo after seconds was measured. In addition, this operation, that is, charging for 20 seconds - dark decay for 20 seconds - light irradiation for 30 seconds, is repeated once.
Repeat 0 times, again Va, Vo, B% and VDi
o was measured. The above results are shown in Table-2.

Table 2 Effects As can be seen from the results in Table 2, the laminated electrophotographic photoreceptor according to the present invention showed no increase in residual potential compared to the conventional one (comparative example), and had a similar sensitivity. .

1 Indication of the case 1982 Patent Application No. 71451 2 Name of the invention Electrophotographic photoreceptor 3 Relationship with the case Patent applicant 1-3 Nakamagome, Ota-ku, Tokyo @ 6 (674 ) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 5, Column 6 of "Detailed explanation of the invention in Part 1 of the specification subject to amendment", content of the amendment, page 4, line 13, "Causing a decline ”, change the line and add the following.

1.Object The present invention provides an electrophotographic photoreceptor in which the increase in residual potential is suppressed to a minimum and has good sensitivity.

1 that's all

Claims (1)

[Claims] 1. A laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially provided on a conductive support, characterized in that the charge generation layer contains powder of a metal material having a contact potential difference with respect to Au of 10,100 O or less. A photoreceptor for electrophotography.