JPH01142654A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having high sensitivity and low residual potential by incorporating a specified pyrrolopyrrole compd. and a specified conjugated compd. into a photosensitive layer. CONSTITUTION:The title photosensitive body has a photosensitive layer formed on an electroconductive layer, and a pyrrolopyrrole compd. expressed by formula I and a conjugated compd. expressed by formula II are contained in the photosensitive layer. In formula I and II, each R<1> and R<2> is an aralkyl group, or a heterocyclic group, etc.; each R<3> and R<4> is H atom. or alkyl group, etc.; each R<5>-R<8> is an H atom. or a lower alkyl group, etc. The pyrrolopyrrole compd. expressed by formula I and the conjugated compd. expressed by formula II are used singly or as a mixture of >=2 kinds thereof. By this constitution, an electrophotographic sensitive body having high light stability, high sensitivity, and low residual potential is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor suitably used in an image forming apparatus such as a copying machine.

<Problems to be solved by conventional technology and inventions> In recent years,
As an electrophotographic photoreceptor in image forming devices such as copying machines, this photoreceptor has a high degree of freedom in functional design, and includes a charge-generating material that generates charges when irradiated with light and a charge-transporting material that transports the generated charges. For example, a single-layer photosensitive layer containing a charge generating material, a charge transporting material, and a binder resin, or a charge generating layer containing the above charge generating material, a charge transporting material, and a binder resin. A functionally separated electrophotographic photoreceptor has been proposed, which includes a laminated photosensitive layer in which a charge transport layer and a charge transport layer are laminated.

Further, when forming a copy image using an electrophotographic photoreceptor, the Carlson process is widely used. This Carlson process consists of a charging process in which a photoreceptor is uniformly charged by corona discharge, an exposure process in which an original image is exposed to the charged photoreceptor to form an electrostatic latent image corresponding to the original image.
A development process in which an electrostatic latent image is developed with a developer containing toner to form a toner image, a transfer process in which the toner image is transferred to a base material such as paper, and a toner image transferred to the base material is fixed. The basic steps include a fixing process and a cleaning process to remove toner remaining on the photoreceptor after the transfer process. In order to form high-quality images in the Carlson process, the electrophotographic photoreceptor must be , they are required to have excellent charging properties and photosensitive properties, and to have a low residual potential after exposure.

On the other hand, the electrophotographic properties of the functionally separated electrophotographic photoreceptor are largely influenced by the combination of the charge generating material and the charge transporting material. For example, pyrrolovirol compounds proposed as charge-generating materials (Japanese Patent Laid-Open No. 61-16255
5) and a hydrazone compound such as N-ethyl-3-rubazolylaldehyde N,N-diphenylhydrazone, the above hydrazone compound is , the dependence of drift mobility on electric field strength is large, the residual potential of the photoreceptor is high, and the sensitivity is insufficient. Moreover, the above hydrazone compounds are easily photoisomerized and photodimerized by light irradiation, so
There is a problem that the photostability is still insufficient, and that the sensitivity decreases and the residual potential increases with repeated use.

In view of the above points, the applicant first proposed that N,N'-bis(
3,5-dimethylphenyl)perylene-3,4,9,1
Electrophotography having a photosensitive layer consisting of a combination of a perylene compound such as 0-tetracarboxydiimide and a conjugated compound such as 1,1-diphenyl-434-bis(4-dimethylamino)phenyl-1°3-butadiene. (Japanese Patent Application No. 62-1275137).

However, an electrophotographic photoreceptor having a photosensitive layer made of a combination of a perylene compound and the above-mentioned conjugated compound,
Perhaps because the characteristics of each of the above-mentioned materials are not sufficient, there are still problems such as insufficient sensitivity, high residual potential, and insufficient image quality.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrophotographic photoreceptor that has excellent photostability, high sensitivity, and low residual potential.

Means and Effects for Solving the Problems> In order to achieve the above object, the electrophotographic photoreceptor of the present invention is a photoreceptor in which a photoreceptor layer is formed on a conductive base material, the photoreceptor comprising: It is characterized by containing a pyrrolovirol compound represented by the following general formula (1) and a conjugated compound represented by the following general formula (2).

(In the formula, R1 and R2 are the same or different, and are an aryl group or an aralkyl group that may have a substituent,
It represents a heterocyclic group, and R3 and R4 are the same or different and represent a hydrogen atom, an alkyl group, or an aryl group which may have a substituent. ) (In the formula, R5, R6, R7 and R8 are each selected from a hydrogen atom, a lower alkyl group, and an aryl group which may have a substituent, and at least one of R5 and R6, and R7 and R8 At least one of them shall have an aryl group which may have a substituent.) The present invention will be described in detail below.

In the electrophotographic photoreceptor of the present invention, a photosensitive layer is formed on a conductive base material, and the photosensitive layer contains a pyrrolovirol compound represented by the general formula (1) and a pyrrolovirol compound represented by the general formula (2). Contains the conjugated compounds shown below.

The above-mentioned conductive base material may be in the form of a sheet or a drum, and either the base material itself has conductivity or the surface of the base material has conductivity and has sufficient mechanical strength when used. Preferably. As the conductive base material, various conductive materials can be used, such as aluminum, copper,
tin, platinum, gold, silver, vanadium, molybdenum, chromium,
Examples include simple metals such as cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, plastic materials on which the above metals are vapor-deposited or laminated, and glass coated with aluminum iodide, tin oxide, indium oxide, etc. Ru. Among the conductive substrates mentioned above, aluminum, especially aluminum crystal grains, are not present on the surface, which prevents black spots and pinholes from occurring in copied images, etc., and improves the adhesion between the photosensitive layer and the substrate. In order to improve
Alumite-treated aluminum, in particular, the thickness of the alumite-treated layer is 5 to 12 μm, and the surface roughness is 1.5S.
The following anodized aluminum is preferred.

In the pyrrolovirol compound represented by the general formula (1) contained in the photosensitive layer, examples of the aryl groups of R1 and R2 include phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, and 1-pyrenyl groups, and phenyl group, naphthyl group, and phenyl group is particularly preferred.

Examples of the aralkyl group include benzyl, phenylethyl, and naphthylmethyl groups.

The substituent in the aryl group or aralkyl group which may have a substituent is selected from the group consisting of a halogen atom, a lower alkyl group having a halogen atom, a cyano group, an alkyl group, an alkoxy group, and a dialkylamino group. Examples include substituents.

Examples of the halogen atom include fluorine, chlorine, bromine, and iodine, with chlorine or bromine atoms being preferred.

In addition, examples of alkyl groups having a halogen atom include chloromethyl, dichloromethyl, trichloromethyl, 2-chloroethyl, 2.2-dichloroethyl, 2,2.2-1
Examples include -dichloroethyl and trifluoromethyl groups.

Alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl,
Examples include alkyl groups having 1 to 18 carbon atoms such as pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and stearyl groups. Among the above alkyl groups, a straight chain or branched alkyl group having 1 to 12 carbon atoms,
Particularly preferred are straight-chain or branched lower alkyl groups having 1 to 6 carbon atoms, especially straight-chain or branched lower alkyl groups having 1 to 4 carbon atoms.

Alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, ter
Examples include t-butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, and stearyloxy groups. Among the above alkoxy groups,
Straight chain or branched chain alkoxy groups having 1 to 12 carbon atoms, particularly straight chain or branched lower alkoxy groups having 1 to 6 carbon atoms, particularly preferred are straight chain or branched lower alkoxy groups having 1 to 4 carbon atoms. .

Examples of the dialkylamino group include dimethylamino, diethylamino, methylethylamino, dipropylamino, diisopropylamino, dibutylamino, diisobutylamino, di-tert-butylamino, diethylamino,
The number of carbon atoms in the alkyl moiety such as diacylamino group is 1 to 6
An example is a dialkylamino group.

Examples of polycyclic groups include thienyl, thianthrenyl, furyl, pyranyl, isobenzofuranyl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, imidazolyl, pyrazolyl, isothiazolyl, isoxasilyl, intridinyl, isoindolyl, indolyl, imidazolyl, and purinyl. , pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinarinyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, buteridinyl, carbazolyl, carbolinyl, phenoxazinyl, acridinyl,
Berimidinyl, phenanthrolinyl, phthalazinyl, phenarsazinyl, phenothiazinyl, furazanyl, phenoxazinyl, isochromanyl, chromanil, pyrrolidinyl, pyrrolinyl, imidazolidinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl, piperidyl, piperidino, piperazinyl, indolinyl, isoindolinyl, quinuclidinyl, morpholinyl, mol phorino group , or a fused heterocyclic group of a fused heterocyclic compound obtained by ortho- or helicondensation of a compound having the above-mentioned heterocyclic group and an aryl compound.

In addition, in the pyrrolovirol compound represented by the above general formula (1), as the alkyl groups of R3 and R4,
Examples include lower alkyl groups having 1 to 6 carbon atoms as the substituents R1 and R2. Among the above alkyl groups, alkyl groups having 1 to 4 carbon atoms are preferred.

In addition, aryl groups that may have any substituents include:
A phenyl group which may have a substituent on the phenyl ring is preferred, and the substituent for the phenyl group includes a halogen atom, a lower alkyl group having a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, and a nitro group. Preferred are substituents selected from the group consisting of: Examples of the above-mentioned halogen atom, lower alkyl group having a halogen atom, alkyl group, and alkoxy group include the same substituents as the above-mentioned substituents R1 and R2. Alkylthio groups include methylthio, ethylthio, propylthio, isopropylthio,
Butylthio, isobutylthio, tert-butylthio,
Examples include pentylthio, hexylthio, heptylthio, octylthio, nonylthio, decylthio, undecylthio, dodecylthio, and stearylthio groups. Among the above alkylthio groups, straight chain or branched alkylthio groups having 1 to 12 carbon atoms, especially straight chain or branched lower alkylthio groups having 1 to 6 carbon atoms, especially straight chain or branched chain having 1 to 4 carbon atoms. A lower alkylthio group is preferred.

In addition, it is particularly preferable that the above-mentioned substituents R3 and R4 are hydrogen atoms.

Among the above-mentioned pyrrolovirol compounds, preferred compounds include 1,4-dithioketo-3,6-diphenylpyrrolo[3,4-c]virol, 1゜4-dithioketo-3
,6-di(4-tolyl)pyrrolo[3,4-c]virol, 1,4-dithioketo-3,6-di(4-ethylphenyl)pyrrolo[3°4-c]virol, 1.4- Dithioketo-3,6-di(4-propylphenyl)pyrrolo[3
,4-C]virol, 1,4-dithioketo-3,6-di(4-isopropylphenyl)pyrrolo[3,4-C]virol, 1,4-dithioketo-3,6-di(4-butylphenyl) ) pyrrolo[3,4-c] virol, 1,4-
Dithioke 1--3,6-di(4-isobutylphenyl)
pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3,6-di(4-tert-butylphenyl)pyrrolo[3,4-c-copyrrole, 1,4-dithioketo-3,6
-di(4-pentylphenyl)pyrrolo[3,4-cl
Pyrrole, 1,4-dithioketo-3,6-di(4-hexylphenyl)pyrrolo[3,4-cl Pyrrole, 1.
4-dithioketo-3,6-di(3,5-dimethylphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3,6-di(3,4,5-trimethylphenyl)
Pyrrolo[3,4-cl Pyrrole, 1,4-dithioketo-3,6-di(4-methoxyphenyl)pyrrolo[3,4
-cl pyrrole, 1,4-dithioketo-3,6-di(
4-ethoxyphenyl)pyrrolo[3,4-c-copyrrole, 1゜4-dithioketo-3,6-di(4-propoxyphenyl)pyrroloE3,4-C-copyrrole, 1,4-cythioketo-3,6-di (4-isopropoxyphenyl)pyrrolo[3,4-cl pyrrole, 1°4-dithioketo-
3,6-di(4-butoxyphenyl)pyrrolo[3,4-
c co-pyrrole, 1,4-dithioketo-3,6-di(4
-isobutoxyphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3,6-di(4-tert
-butoxyphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketol 3.6-di(4-pentyloxyphenyl)pyrrolo[3,4-c]copyrrole 1°4-
Dithioketo-3,6-di(4-hexyloxyphenyl)pyrrolo[3,4-cl Pyrrole, 1°4-dithioketo-3,
6-di(3,4,5-trimethoxyphenyl)pyrrolo[
3,4-cl pyrrole, 1,4-dithioketo-3,6
-dibenzylpyrrolo[3,4-C] pyrrole, 1,4
-dithioketo-3,6-dinaphthylpyrrolo[3,4-c
Copyrrole, 1,4-dithioketo-3,6-di(4-cyanophenyl)pyrrolo[3,4-cl Pyrrole, 1.
4-dithioketo-3,6-di(4-chlorophenyl)pyrrolo[3,4-c-pyrrole, 1,4-dithioketo-
3,6-di(2-promophenylpyrrolo[3,4-c
l Pyrrole, 1,4-dithioketo-3,6-di(4-
trifluoromethylphenyl)pyrrolo[3,4-cl
Pyrrole, 1,4-dithioketo-3,6-di(4-dimethylaminophenyl)pyrrolo[3,1-C1 pyrrole,
1.4-Sithioketo-3,6-di(4-diethylaminophenyl)bi0OC3,4-ccopyrrole, N.

N'-dimethyl-1,4-dithioketo-3,6-diphenylpyrrolo[3,4-cl pyrrole, NIN'-dimethyl-1,4-dithioketo-3,6-diphenylpyrrolo[
3,4-cl pyrrole, N.

N'-dimethyl-1,4-dithioketo-3,6-di(4
-ethylphenyl)pyrrolo[3,4-c]copyrrole N
, N'-dimethyl-1,4-dithioketo-3,6-di(
4-isopropylphenyl)pyrrolo[3,4-ccopyrrole, N,N'-dimethyl-1,4-dithioketo-3
,6-di(4-tert-butylphenyl)pyrrolo[3
,4-cl pyrrole, N,N'-dimethyl-1,4-
dithioketo-3,6-di(3,4,5-)dimethylphenyl)pyrrolo[3,4-cl pyrrole, N,N'-
Dimethyl-1,4-dithioketo-3,6-di(4-methoxyphenyl)pyrrolo[3,4-cl pyrrole, N,
N'-dimethyl-114-dithioketo-3,6-di(
4-ethoxyphenyl)pyrrolo[3,4-cl pyrrole, N,N'-di,methyl-1,4-dithioketo-3
,6-di(4-isopropoxyphenyl)pyrrolo[3,
4-c Copyrrole, N,N'-dimethyl-1,4-dithioketo-3゜6-di(4-tert-butoxyphenyl)pyrrolo[3,4-cl Pyrrole, N,N'-dimethyl-1,4 -dithioketo-3,6-di(3,4,5-
trimethoxyphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3,6-di(3-pyrrolyl)
Pyrrolo[3,4-cl Pyrrole, 1゜4-dithioketo-3,6-di(4-oxacylyl)pyrrolo[3,4-c
l Pyrrole, 1,4-dithioketo-3,6-di(4-
thiazolyl)pyrrolo[3゜4-C]copyrrole 1,4-
Dithioketo-3,6-diimidazolylpyrrolo[3,4-
cl Virol, 1,4-dithioketo-3,6-di(
2-imidazolyl)bio[3,4-cl virol, 1,4-dithioketo-3,6-di(4-imidazolyl)pyrrolo[3,4-c virol, 1,4-dithioketo-3,6- di(4-pyridyl)pyrrolo[3,4-C copyrrole, 1,4-dithioketo-3,6-di(2-pyrimidinyl)pyrrolo[3,4-cl virol, 1.4-
Dithioketo-3,6-dibiberidinovirolo C3,4-c
] Virol, 1,4-dithioketo-3,6-di(4-
piperidinyl) pyrrolo[3,4-cl virol, 1.
4-dithioketo-3,6-dimorpholinovirolo[3,4
-cl Virol, 1,4-dithioketo-3,6-di(
2-quinolyl)pyrrolo[3,4-cl Virol, 1゜4-dithioketo-3,6-di(3-benzo[blthiophenyl)pyrrolo[3,4-cl Virol, 1,4-dithioketo-3,6 -di(2-quinolyl)pyrrolo[3,4
-cl virol, N,N'-dimethyl-1,4-dithioketo-3,6-di(4-imidazolyl)pyrrolo[3
,4-cl Virol, N.

N'-dimethyl-1,4-dithioketo-3,6-dimorpholinopyrrolo[3,4-cl virol, N.

N'-dimethyl-1,4-dithioketo-3,6-di(4
-pyridyl)pyrrolo[3,4-cl pyrrole and the like.

The pyrrolovirol compounds represented by the above general formula (1) may be used alone or in combination of two or more.

Further, the pyrrolopyrrole compound represented by the above general formula (1) may be used in combination with various charge generating materials within the range that does not impair the photosensitivity properties. Examples of the charge generating material include selenium, selenium-tellurium, amorphous silicon, biryllium salts, azo compounds, disazo compounds, phthalocyanine compounds, anthanthrone compounds, perylene compounds, indigo compounds, and triphenylmethane compounds. Compounds, threne-based compounds, toluidine-based compounds, pyrazoline-based compounds, quinacridone-based compounds, and the like are exemplified. One or more types of the above charge generating materials may be used.

Note that the charge generating material described above can be selected as appropriate.

Furthermore, in the conjugated compound represented by the above general formula (2), the lower alkyl groups and aryl groups of R5, R6, R7 and R8 are exemplified by the same lower alkyl groups and aryl groups as in R1 and R2 above. be done.

Examples of substituents for the aryl group include, in addition to lower alkyl groups and lower alkoxy groups, amino groups, monoalkylamino groups such as methylamino and ethylamino groups, and the aforementioned dialkylamino groups. Among the above substituents,
A dialkylamino group is preferred.

In addition, in the compound represented by the above general formula (■), R5,
At least one of R6 and at least one of R7 and R8 must have an aryl group which may have the above-mentioned substituent. R5 and R6
, or when R7 and R8 are both hydrogen atoms or lower alkyl groups, the sensitivity of the photoreceptor is low and the residual potential is large, and it is difficult to stabilize the photosensitive characteristics and electrical characteristics.

In addition, 1,1-bis(4-diethylaminophenyl)-6,6-diphenyl-1,3,5-hexatriene and the like have been proposed as compounds similar to the compound represented by the above general formula (2). However, these compounds require a large number of reaction steps during synthesis, are prone to side reactions, are difficult to separate and purify the target compound, and tend to contain a large amount of impurities. Furthermore, when a photoreceptor is constructed due to insufficient charge transport ability, perhaps due to decreased compatibility with the binder resin, the sensitivity is low and the residual potential is high.

Among the conjugated compounds represented by the above-mentioned -Sakakuguchi, preferred compounds include, for example, 1,1,4゜4-tetraphenyl-1,3-butadiene, 1゜4-dimethyl-1-(
4-dimethylaminophenyl)-4-phenyl-1,3
-butadiene, 1-methyl-1-(4-dimethylaminophenyl)-4,4-diphenyl-1,3-butadiene, 1-ethyl-1-(4-dimethylaminophenyl)-
4-methyl-4-phenyl-1,3-butadiene, 1-
Methyl-1-(4-diethylaminophenyl)-4,4
-diphenyl-1,3-butadiene, 1-ethyl-1-
(4-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene, 1゜1-bis(4-dimethylaminophenyl)-4゜4-diphenyl-1,3-butadiene 1,1.1-bis (4-diethylaminophenyl)
-4,4-diphenyl-1,3-butadiene, 1,1-
Bis(4-dipropylaminophenyl')-4,4-diphenyl-1,3-butadiene, 1.1-bis(4-dibutylaminophenyl)-4,4-diphenyl-1,3
-butadiene, 1,1,4.4-tetra(4-dimethylaminophenyl)-1,3-butadiene, 1,1,4.
4-tetra(4-diethylaminophenyl)-1,3-
Butadiene, 1,1-bis(4-dimethylaminophenyl)-4,4-bis(4-diethylaminophenyl)-
Examples include 1,3-butadiene.

In addition, the conjugated compound represented by the above-mentioned -Sakuhatsu (2) is -
m or a mixture of two or more.

In addition, the conjugated compound represented by the above-mentioned (2) can be used in combination with the pyrrolobilol-based compound represented by the above-mentioned (1) to form a photosensitive layer, thereby producing a photoreceptor with high sensitivity and low residual potential. However, if necessary, it may be used in combination with other charge transport materials as long as the charging characteristics, photosensitivity characteristics, etc. are not impaired. Examples of the other charge transport materials include fluorenone compounds such as tetracyanoethylene, 2,4,7-)linitro-9-fluorenone, 2,4
．． Nitrated compounds such as 8-trinitrothioxanthone and dinitroanthracene, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,5-di(4-dimethylaminophenyl)-1,3,4-oxadiazole, etc. oxadiazole compounds, nostyryl compounds such as 9-(4-diethylaminostyryl)anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline, 4 .4', 4'-tris(4-diethylaminophenyl)triphenylamine,
4,4'-bis[N-phenyl-N-(3-methylphenyl)aminocodiphenyl, 4゜4'-bis[N,N
amine derivatives such as -di(4-methylphenyl)amino]-3,3'-dimethyldiphenyl, 4-(N,N
-diethylamino)benzaldehyde Hydrazone compounds such as N,N-diphenylhydrazone, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, etc. Examples include nitrogen-containing cyclic compounds and fused polycyclic compounds. Note that the photoconductive polymer as the charge transporting material, such as poly-N-vinylcarbazole, may be used as a binder resin.

In addition, the photosensitive layer includes terphenyl, halonaphthoquinones,
Conventionally known sensitizers such as acenaphthylene, 9-(N,N
It may contain various additives such as fluorene compounds such as -diphenylhydrazino)fluorene and 9-carbazolyliminofluorene, deterioration inhibitors such as plasticizers, antioxidants, and ultraviolet absorbers.

The pyrrolovirol compound represented by the above-mentioned -Sakatsu (1) as a charge generating material and the general formula (
The photosensitive layer containing the conjugated compound represented by 2) includes a pyrrolobilol compound represented by -Sakaburu (1), a conjugated compound represented by -Sakaburu (2) above, and a binder resin. A single-layer type photosensitive layer containing at least general formula (1)
Any of the laminated photosensitive layers in which a charge generation layer containing a pyrrolobilol compound represented by the formula (2) and a charge transport layer containing a conjugated compound represented by (2) above and a binder resin are laminated. It may be. Further, in the laminated photosensitive layer, the charge transport layer may be formed on the charge generation layer, or conversely, the charge generation layer may be formed on the charge transport layer.

In addition, various binder resins can be used, such as styrene polymers, acrylic polymers, styrene-acrylic copolymers, polyethylene, engineered styrene-vinyl acetate copolymers, chlorinated polyethylene, polypropylene, and ionomers. Olefin polymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl Butyral resin, polyether resin, phenol resin, photocurable resin such as epoxy acrylate, etc.
Various polymers are exemplified. One or more types of the above-mentioned binder resins may be used.

The ratio of the pyrrolopyrrole compound represented by the general formula (1), the conjugated compound represented by Ikkakuburu (■), and the binder resin in the single-layer photosensitive layer is not particularly limited, and can be used in a desired electrophotographic manner. They can be selected as appropriate depending on the characteristics of the photoreceptor used, but 2 to 20 parts by weight, especially 3 to 15 parts by weight of a pyrrolopyrrole compound, and 40 to 200 parts by weight of a conjugated compound to 100 parts by weight of the binder resin. parts, especially 50 to 100 parts by weight. If the amount of the pyrrolovirol compound and the conjugated compound is less than the above-mentioned amount, not only the sensitivity of the photoreceptor will not be sufficient, but also the residual potential will become large. Further, if the amount exceeds the above range, the abrasion resistance of the photoreceptor will not be sufficient.

The single-layer type photosensitive layer may have an appropriate thickness, but 1
Thicknesses of 0 to 50 μm, particularly 15 to 25 μm are preferred.

Further, the charge generation layer in the laminated photosensitive layer may be formed of a vapor-deposited film, a sputtered film, etc. made of a pyrrolopyrrole compound represented by the above-mentioned -Sakatsu (1), and the charge generation layer is formed together with a binder resin. If formed, the ratio of the pyrrolopyrrole compound and the binder resin in the charge generation layer can be set as appropriate, but the binder resin 10
Preferably, the amount of the pyrrolopyrrole compound is 5 to 500 parts by weight, particularly 10 to 25 parts by weight, based on 0 parts by weight.

If the amount of the pyrrolopyrrole compound is less than 5 parts by weight, the charge generation ability will be low, and if it exceeds 500 parts by weight, there will be problems such as decreased adhesion. The charge generation layer may have an appropriate thickness, but is preferably 0.01 to 3 μm, particularly 0.1 to 2 μm.
Preferably, the thickness is on the order of μm.

Furthermore, the ratio of the conjugated compound represented by general formula (2) and the binder resin in the charge transport layer can be set as appropriate;
~500 parts by weight, especially 25-200 parts by weight,
is preferable. If the amount of the conjugated compound is less than 10 parts by weight, the charge transport ability will not be sufficient, and if it exceeds 500 parts by weight, the mechanical strength etc. of the charge transport layer will decrease. The charge transport layer may have an appropriate thickness, and may have a thickness of 2 to 100 μm.
A thickness of about 5 to 30 μm is particularly preferable.

Further, the charge generation layer may contain the conjugated compound as a charge transport material together with the pyrrolobilol compound as the charge generation material, and in this case, the pyrrolobilol compound and the conjugated compound in the charge generation layer are bonded together. The ratio of the binder resin to the binder resin is determined as appropriate, but it is preferable that the composition be composed of the pyrrolopyrrole compound, the conjugated compound, and the binder resin in the same ratio as in the single-layer photosensitive layer. Also,
The charge generation layer having the ratio as described above is formed to have an appropriate thickness, and is formed to have a thickness of about 0.1 to 50 μm.

The single-layer type photosensitive layer is prepared by preparing a photosensitive layer dispersion containing the pyrrolopyrrole compound, a conjugated compound, a binder resin, etc., applying the dispersion to the conductive substrate, and drying or curing the dispersion. It can be formed by Also,
The laminated photosensitive layer is prepared by preparing a dispersion liquid for a charge generation layer containing a pyrrolovirol compound and a binder resin, and a coating liquid for a charge transport layer containing the conjugated compound and a binder resin. It can be formed by sequentially applying it to a base material and drying or curing it.

Further, when preparing the above-mentioned dispersion liquid, etc., various organic solvents can be used depending on the type of binder resin etc. used. The above-mentioned solvents include aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, and dimethyl ether. , ethers such as diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, cyclohexanone, esters such as ethyl acetate, methyl acetate, dimethyl formamide, dimethyl sulfoxide, etc. The following solvents are exemplified and may be used alone or in combination of two or more. In addition, when preparing the above-mentioned dispersion liquid, etc., a surfactant, a leveling agent, etc. may be used in combination in order to improve dispersibility, coating properties, etc.

In addition, the above-mentioned dispersion liquid can be prepared using conventional methods such as mixer, ball mill, paint shaker, sand mill, etc.
It can be prepared using an attritor, an ultrasonic disperser, etc., and the obtained dispersion etc. is applied to the conductive substrate,
The electrophotographic photoreceptor of the present invention can be obtained by heating to remove the solvent.

Incidentally, in order to improve the adhesion between the conductive base material and the photosensitive layer, an undercoat layer may be formed between the conductive base material and the photosensitive layer. The undercoat layer is formed by applying a solution containing a natural or synthetic polymer so that the film thickness after drying is approximately 0.01 to 1 μm.

Further, in order to improve the adhesion between the conductive base material and the photosensitive layer, the conductive base material may be treated with a surface treatment agent such as a silane coupling agent or a titanium coupling agent. Furthermore, in order to protect the photosensitive layer, a surface protective layer may be formed on the photosensitive layer. The surface protective layer is usually formed by drying the various binder resins or a mixture of the binder resin and additives such as deterioration inhibitors to a film thickness of 0.1 to 10μ11, preferably 0.
．． It is formed by coating to a thickness of about 2 to 5 μm.

In the electrophotographic photoreceptor of the present invention, the photosensitive layer has the above-described
Since it contains the pyrrolobilol compound represented by 1) and the conjugated compound represented by -x-0, it has excellent photostability, high sensitivity and surface potential, and low residual potential. Therefore, the electrophotographic photoreceptor of the present invention is useful as a photoreceptor used in copying machines, laser beam printers, and the like.

<Examples> The present invention will be described in more detail below based on Examples.

An electrophotographic photoreceptor having a laminated photosensitive layer was prepared as follows using the following pyrrolobilol compound as a charge generating material and the following conjugated compound as a charge transporting material.

Pyrrolopyrrole compounds The above pyrrolopyrrole compounds and conjugated compounds are indicated by the following abbreviations in Tables 1 to 3.

A: l,4-dithioketo-3,6-diphenylpyrrolo[
3,4-cl Virol B: l,4-dithioketo-3,6-di(4-tolyl)pyrrolo[3,4-cl Virol C: 1,4-dithioketo-3,6-di(4-methoxyphenyl) ) Pirolo [3,4
-c] Pyrrole D: l,4-dithioketo-3,6-dinithylpyrrolo[3
,4-cl Pyrrole E: N,N'-diethyl-1,4-dithioke 1--3.
6-di-tert-butylpyrrolo[3,4-cl Virol F: 1,4-dithioketo-3,6-distearylpyrrolo[3,4-cl Virol G: N,N'-dimethyl-1,4-dithioketo- 3,6
-dibenzylpyrrolo[3,4-C-copyrroloH: 1,4-dithioketo-3,6-dinaphthylpyrrolo[
3,4-cl Virol 1: 1,4-dithioketo-3,6-di(4-pyridyl)
Pyrrolo[3,4-cl Virol 1: N,N'-diethyl-1,4-dithioketo-3,6
-di(2-quinolyl)pyrrolo[3,4-cl to virol: N,N'-diethyl-1,4-dithioke 1--3.
6-di(4-chlorophenyl)pyrrolo[3,4-c
Pyrrole L+1,4-dithioketo-3,6-di[4-(2,2,
2-trifluoroethyl)phenylcohydrolo[3,4-
c] l:” roll M: l,4-dithioketo-3,6
-di(4-diethylaminophenyl)pyrrolo[3゜4-
C] Virol N: N,N'-dimethyl-1,4-dithioketo-3,6
-di(4-hexyloxyphenyl)pyrrolo[3,4-
c] Pyrrole 0:l,4-dithioketo-3,6-di(
4-cyanophenyl)pyrrolo[3□4-C]pyrrole P: l,4-dithioketo-3,6-di(2-bromophenyl)pyrrolo[3,4-c]pyrrole Q: N,N'-diethyl -1,4-dithioketo-3,6
-di(4-dodecylphenyl)pyrrolo[3,4-c]
Pyrrole 1: 1,4-dimethyl-1-(4-dimethylaminophenyl)-4-phenyl-1゜3-butadiene 2: 1-methyl-1-(4-dimethylaminophenyl)
-4,4-diphenyl-1゜3-butadiene 3:]-]ethyl-1-4-diethylaminophenyl)
-4-Methyl-4-phenyl-1,3-butadiene 4:1,1-bis(4-dimethylaminophenyl)-4
,4-diphenyl-1,3-butadiene5:1.1-bis(4-diethylaminophenyl)-4
,4-diphenyl-1,3-butadiene6:1,1-bis(4-dipropylaminophenyl)-
4,4-diphenyl-1°3-butadiene 7:1,1-bis(4-dimethylaminophenyl)-4
,4-bis(4-diethylaminophenyl)-1,3-
Butadiene Examples 1 to 20 10 parts by weight of the above pyrrolopyrrole compound shown in Tables 1 to 3 as a charge generating material, vinyl chloride-vinyl monoacetate copolymer (manufactured by Tsukimizu Kagaku Kogyo Co., Ltd., product 1 Meiko Slek C) A charge generation layer coating solution consisting of 10 parts by weight and a predetermined amount of keto-norahydrofuran is prepared, and the obtained coating solution is applied onto an aluminum sheet and heated at a temperature of 100° C. for 30 minutes. Thick 0.5
A charge generation layer of .mu.m was formed. 1. Next, using the above conjugated compounds shown in Tables 1 to 3 as a charge transport material,
A charge transport layer was formed. That is, 7 parts by weight of the conjugated compounds shown in Tables 1 to 3, bisphenol Z type car recarbonate: (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name PCZ)
)IQ parts by weight and a predetermined amount of benzene are mixed and dissolved to prepare a charge transport two layer coating solution, coated on the charge generation layer, and heated and dried to form a charge of 215 μm in film thickness. An electrophotographic photoreceptor having a laminated photoreceptor layer was prepared by forming a transport layer.
Comparative Example 1 In place of the conjugated compound of Example 1, N-ethyl-3-carbazolyl aldehyde N,N-diphenylhydrazone was used, and in the same manner as in the above example, an electron beam having a front-layer type photosensitive layer was prepared. Comparative Example 2 A photographic photoreceptor was prepared. In place of the pyrrolopyrrole compound of Example 4,
-bis(3,5-dimethylphenyl)perylene-3,4
, 9,10-tetracarboxydiimide, an electrophotographic photoreceptor having laminated sensitization was prepared in the same manner as in the above example.

Then, using an electrostatic copying paper tester (manufactured by Kawaguchi Electric Co., Ltd., model 5P-128) to examine the charging characteristics and photosensitivity characteristics of the electrophotographic photoreceptors obtained in the above examples and comparative examples,
-6, By performing Coroto discharge under OKV conditions,
The electrophotographic photoreceptors of each of the Examples and Seven Comparative Examples were negatively charged. Mako, the initial surface potential of each photoreceptor Vs, p, (
In addition to measuring V), the surface of the photoreceptor was exposed using a 10 lux tungsten lamp, and the surface potential V s
, p.

Find the time it takes for
(μJ/cm) was calculated. Furthermore, after exposure,
The surface potential after 0.15 seconds is the residual potential Vr, p, m
And so.

Tables 1 to 3 show the charging characteristics, photosensitive characteristics, etc. of each electrophotographic photoreceptor obtained in the above Examples and Comparative Examples.

(Hereinafter, blank space) As shown in Tables 1 to 3, the electrophotographic photoreceptors of comparative examples were:
It was found that both had low sensitivity and high residual potential. On the other hand, all of the electrophotographic photoreceptors of Examples were found to have high sensitivity and low residual potential.

<Effects of the Invention> As described above, according to the electrophotographic photoreceptor of the present invention, the photosensitive layer contains a pyrrolovirol compound represented by the general formula (1) and a compound represented by the general formula (2). Since it contains a conjugated compound, it has the unique effects of high sensitivity and low residual potential.

Claims (1)

[Scope of Claims] 1. A photoreceptor in which a photosensitive layer is formed on a conductive base material, in which the photosensitive layer comprises a pyrrolopyrrole compound represented by the following general formula (1) and a pyrrolopyrrole compound represented by the following general formula (2). ) A photoreceptor for electrophotography, characterized by containing a conjugated compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (In the formula, R^1 and R^2 are the same or different,
It represents an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, and R^3 and R^4 are the same or different, and represent a hydrogen atom, an alkyl group, or an aryl group which may have a substituent. Indicates the group. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (In the formula, R^5, R^6, R^7, and R^8 each have a hydrogen atom, a lower alkyl group, or a substituent, but Selected from good aryl groups, at least one of R^5, R^6, and at least one of R^7, R^8 has an aryl group that may have a substituent. ) 2. In R^1 and R^2, the substituent of the aryl group or aralkyl group which may have a substituent is a halogen atom, a lower alkyl group having a halogen atom, a cyano group, or an alkyl group. The electrophotographic photoreceptor according to claim 1, wherein the substituent is a substituent selected from the group consisting of a group consisting of an alkoxy group, an alkoxy group, and a dialkylamino group. 3. R^3 and R^4 are a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, or a halogen atom, a lower alkyl group having a halogen atom on the phenyl ring, an alkyl group,
The electrophotographic photoreceptor according to claim 1, which is a phenyl group optionally having a substituent selected from the group consisting of an alkoxy group, an alkylthio group, and a nitro group. 4. The above claims, wherein the aryl group which may have a substituent in R^5, R^6, R^7 and R^8 is a phenyl group which may have a dialkylamino group. 2. The electrophotographic photoreceptor according to item 1.