JPH03144652A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce residual potential by incorporating a specified pyrrolopyrrole derivative and a specified oxazole derivative in a photosensitive layer. CONSTITUTION:The photosensitive layer contains the pyrrolopyrrole derivative represented by formula I and the oxazole derivative represented by formula II, and in formulae I and II, each of R<1> and R<2> is an optionally substituted aryl or aralkyl or heterocyclic group of each optionally same or different; each of R<3> and R<4> is H, alkyl, optionally substituted aryl, and each optionally same or different; each of R<5> and R<6> is optionally substituted lower dialkylamino and each optionally same or different; and R<7> is H, halogen, lower alkyl, or lower alkoxy, thus permitting sensitivity to be enhanced and residual potential to be reduced.

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, pyrrolopyrrole compounds proposed as charge-generating materials (Japanese Patent Application Laid-Open No. 81-16255
5) and a hydrazone compound such as N-ethyl-3-rubazolylaldehyde N,N-diphenylhydrazone, the 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. In addition, the hydrazone compounds are easily photoisomerized and photodimerized by light irradiation, so they still have insufficient photostability, and there are problems in that sensitivity decreases and 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
It has a photosensitive layer consisting of a combination of a perylene compound such as 0-tetracarboxydiimide and a conjugated compound such as 1,1-diphenyl-4゜4-bis(4-dimethylamino)phenyl-1゜3-butadiene. He proposed a photoreceptor for electrophotography (Japanese Patent Application No. 127587/1982).

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 has a photoreceptor layer formed on a conductive substrate, and the photoreceptor has the following: Contains a pyrrolopyrrole compound represented by the general formula (1) and an oxazole compound represented by the following general formula (2) (R+ and R2 are the same or different and have a substituent. R3 and R4 are the same or different and represent an aryl group that may have a hydrogen atom, an alkyl group, or a substituent. (In the formula, R5 and R5 are the same or different and represent a lower dialkylamino group which may have a substituent, R7 is a hydrogen atom,
Indicates a halogen atom, lower alkyl group, or lower alkoxy group. 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 pyrrolopyrrole compound represented by the general formula (1) and a compound represented by the general formula (2). It contains an oxazole compound represented by:

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 treatment layer is 5 to 12 μm, and the surface roughness is 1.5
Anodized aluminum of S or less is preferred.

In the pyrrolopyrrole compound represented by the general formula (1) contained in the photosensitive layer, examples of the aryl groups of RI and R2 include phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, and 1-byrenyl groups, Among phenyl groups and naphthyl groups, phenyl groups are 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 /-% 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 selected 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 the heterocyclic group include thienyl, thianthrenyl, furyl, pyranyl, isobenzofuranyl, chromenyl, xanthenyl, phenoxathiinyl, pyrrolyl, imidazolyl, pyrazolyl, isothiazolyl, isoxasilyl, intridinyl, isoindolyl, indolyl, imidazolyl, purinyl, Pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinarinyl, isoquinolyl, quinolyl, phthalazinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, buteridinyl, carbazolyl, carbolinyl, phenoxazinyl, acridinyl,
Perimidinyl, phenanthrolinyl, phthalazinyl, phenarsazinyl, phenothiazinyl, furazanyl, phenoxazinyl, isochromanyl, chromanyl, pyrrolidinyl, pyrrolinyl, imidazolidinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl, piperidyl, piperidino, piperazinyl, indolinyl, isoindolinyl, quinuclidinyl, morpholinyl, Morpholino 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 pyrrolopyrrole compound represented by the above general formula (1), the alkyl groups of R3 and R4 are as follows:
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, as the aryl group which may have a substituent,
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 halogen atom, lower alkyl group, alkyl group, and alkoxy group having a halogen atom include the same substituents as the above substituents R1 and R2. Examples of the alkylthio group include methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, tert-butylthio, pentylthio, hexylthio, heptylthio, octylthio, nonylthio, decylthio, undecylthio, dodecylthio, stearylthio and the like. 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 pyrrolopyrrole compounds, preferred compounds include 1,4-dithioketo-3,6-diphenylpyrrolo[3,4-cl pyrrole, 1°4-dithioketo-3
, 6-di(4-tolyl)pyrrolo[3,4-C]pyrrole, 1,4-dithioketo-3,6-di(4-ethylphenyl)pyrrolo[3°4-C]pyrrole, 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]pyrrole, 1,4-dithioketo-3,6-di(4-butylphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3,6 -di(4-isobutylphenyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo-3
,6-di(4-tert-butylphenyl)pyrrolo[3
,4-cl pyrrole, 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 virol, 1,4-dithioketo-3,6-di(3,4,5-trimethylphenyl)pyrrolo[3, 4-C copyrrole, 1,4-dithioketo-3
,6-di(4-methoxyphenyl)pyrrolo[3,4-c
l Virol, 1,4-dithioketo-3,6-di(4-
ethoxyphenyl)pyrrolo[3,4-cl pyrrole,
1゜4-Dithioketo-3,6-di(4-propoxyphenyl)pyrrolo[3,4-C-copyrrole, 1,4-dithioketo-3,6-di(4-isopropoxyphenyl)pyrrolo[3,4- C-copyrrole, 1゜4-dithioketo-3,
6-di(4-butoxyphenyl)pyrrolo[3,4-cl
virol, 114-dithioketo-3,6-di(4-isobutoxyphenyl)pyrrolo[3,4-C-copyrrole,
1,4-dithioketo-3,6-di(4-tert-butoxyphenyl)pyrrolo[3,4-C-copyrrole, 1.4
-dithioketo-3,6-di(4-pentyloxyphenyl)pyrrolo[3,4-cl Virol, 1°4-dithioketo-3
,6-di(3,5-dimethoxyphenyl)pyrrolo[3,
4-C-copyrrole, 1゜4-dithioketo-3,6-di(
3,4,5-t-rimethoxyphenyl)pyrrolo[3,4
-cl pyrrole, 1,4-dithioketo-3,6-dibenzylpyrrolo[3,4-cl pyrrole, 1,4-dithioketo]-3,6-dinaphthylpyrrolo[3,4-C-copyrrole, 1,4-dithioketo -3,6-di(4-cyanophenyl)pyrrolo[3,4-cl virol, 1,4-dithioketo-3,6-di(4-chlorophenyl)pyrrolo[
3,4-cl virol, 1,4-dithioketo-3,6
-di(2-promopenyl)pyrrolo[3,4-cl virol, 1,4-dithioketo-3,6-di(4-trifluoromethylphenyl)pyrrolo[3,4-cl virol, 1,4-dithioketo- 3,6-di(4-dimethylaminophenyl)pyrrolo[3,4-cl virol, 1.
4-Dithioketo-3,6-di(4-diethylaminophenyl)pyrrolo[3,4-C-copyrrole, N.

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

N'-dimethyl-1,4-dithioketo-3,6-didryl pyrrolo[3,4-cl virol, N+N'-dimethyl-1,4-dithioketo-3,6-di(4-ethylphenyl)pyrrolo[3r 4 - C-copyrrole, N, N'-
Dimethyl-1,4-dithioketo-3,6-di(4-isopropylphenyl)pyrrolo[3,4-C-copyrrole, N
, N'-dimethyl-1,4-dithioketo-3,6-di(4-tert-butylphenyl)pyrrolo[3,4-c
3 Virol, N,N'-dimethyl-1,4-dithioketo-3,6-di(3,4,5-trimethylphenyl)pyrrolo[3,4-cl Virol, N,N'dimethyl-1
,4-dithioketo-3,6-di(4-methoxyphenyl)pyrrolo[3,4-cl pyrrolo, N,N'-dimethyl-1,4-dithioketo-3,6-di(4-ethoxyphenyl)pyrrolo [3,4-c covirol, N, N'
-dimethyl-1,4-dithioketo-3,6-di(4-isopropoxyphenyl)pyrrolo[3,4-cl virol, N,N'-dimethyl-1,4-dithioketo-3゜6
-di(4-tert-butoxyphenyl)pyrrolo[3,
4-C Copyrrole, N,N'-dimethyl-1,4-dithioketo-3,6-di(3,4,5-trimethoxyphenyl)pyrrolo[3,4-cl Virol, 1,4-dithioketo-3 ,6-di(3-pyrrolyl)pyrrolo[3,4-
cl Virol, 1゜4-dithioketo-3,6-di(4
-oxacylyl)pyrrolo[3,4-cl virol, 1
．． 4-dithioketo-3,6-di(4-thiazolyl)pyrrolo[3゜4-c co-virol, 1,4-dithioketo-3
,6-diimidazolylpyrrolo[3,4-cl Virol, 1,4-dithioketo-3,6-di(2-imidazolyl)pyrroloC3,4-cl Virol, 1,4-dithioketo-3,6-di( 4-imidazolyl)pyrrolo[3,4-
cl Virol, 1,4-dithioke)-3,6-di(4
-pyridyl)pyrrolo[3,4-〇copyrol, 1.4
-dithioketo-3,6-di(2-pyrimidinyl)pyrrolo[3,4-cl virol, 1,4-dithioketo-3,
6-diviveridinovirolo[3,4-cl pyrrole, 1
,4-dithioketo-3,6-di(4-piperidinyl)pyrrolo[3,4-cl pyrrole, 1,4-dithioketo=
3,6-dimorpholinobiro[3,4-cl pyrrole, 1,4-dithioketo-3,6-di(2-quinolyl)pyrrolo[3,4-cl pyrrole, 1゜4-dithioketo-
3,6-di(3-benzo[blthiophenyl)pyrroloC
3,4-c]pyrrole, 1,4-dithioketo-3,6-
di(2-quinolyl)pyrrolo[3,4-cl pyrrole,
N,N'-dimethyl-1,4-dithioketo-3,6-
Di(4-imidazolyl)pyrrolo[3,4-cl pyrrole, N.

N'-dimethyl-1,4-dithioketo-3,6-dimorpholinovirolo[3,4-c]pyrrole N.

N'-dimethyl-1,4-dithioketo-3,6-di(4
-pyridyl)pyrrolo[3,4-cl pyrrole and the like are exemplified, with 1,4-dithioketo-3°6-diphenylpyrrolo[3,4-cl pyrrole being particularly preferred.

The pyrrolopyrrole 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, pyrylium 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.

In the oxazole compound represented by the above general formula (2), the halogen atom of R7 may be the same as mentioned above.

Lower alkyl groups include methyl, ethyl, propyl,
Examples include alkyl groups having 1 to 6 carbon atoms such as isopropyl, butyl, isobutyl, tert-butyl, pentyl, and hexyl groups.

Examples of the lower alkoxy group include alkoxy groups having 1 to 3 carbon atoms such as methoxy group, ethoxy group, and propoxy group.

As the lower dialkylamino group, dimethylamino group,
Examples include dialkylamino groups in which the alkyl group has 1 to 3 carbon atoms, such as a diethylamino group, a dipropylamino group, and a diisopropylamino group.

Examples of the substituents bonded to the lower dialkylamino group include benzyl group; phenyl group; halogen atoms such as fluorine, chlorine, bromine, and iodine; alkoxy groups such as methoxy, ethoxy, propoxy, and isopropoxy groups; vinyl,
Examples include alkenyl groups such as allyl, 2-butenyl, 3-butenyl, 1-methylallyl, 2-pentenyl, and 2-hexenyl.

Specifically, lower dialkylamino groups having substituents include dibenzylamino group, dimethylbenzylamino group, diethylbenzylamino group, di(methoxymethyl)amino group, di(ethoxymethyl)amino group, di(vinyl Examples include a methyl)amino group and a di(1-propenylmethyl)amino group.

As the oxazole compound represented by the following general formula (2), the compounds shown in Table 1 can be exemplified.

(Leaving space below) Table 1 Table 1 (Continued) Table 1 (Continued) The oxazole compounds represented by the above general formula (3) may be used alone or in combination of two or more.

The oxazole compound represented by the above general formula (2) is
By forming a photosensitive layer in combination with the pyrrolopyrrole compound represented by the general formula (1), a photoreceptor with high sensitivity and low residual potential can be obtained, but if necessary, charging characteristics, photosensitive characteristics, etc. It may be used in combination with other charge transport materials as long as it does not inhibit the charge transport. As charge transport materials of the above properties,
For example, fluorenone compounds such as tetracyanoethylene, 2,4,7-1-linitro-9-fluorenone, 2
, 4.8-trinidrothioxanthone, nitrated compounds such as dinitroanthracene, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2.5-di(4-dimethylaminophenyl)-1,3,4-oxa Oxadiazole compounds such as diazole, styryl compounds such as 9-(4-diethylaminostyryl)anthracene, carbazole compounds such as polyvinylcarbazole, l-
Pyrazoline compounds such as 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-
Hydrazone compounds such as diethylamino)benzaldehyde N,N-diphenylhydrazone, indole compounds, oxazole compounds, inoxazole compounds, thiazole compounds, thiadiazole compounds,
Examples include nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds, and triazole compounds, and fused polycyclic compounds. Note that the photoconductive polymer as the charge generating material, such as poly-N-vinylcarbazole, may be used as a binder resin.

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

A pyrrolopyrrole compound represented by the general formula (1) above as a charge generating material, and a pyrrolopyrrole compound represented by the general formula (1) as a charge transporting material
The photosensitive layer containing the oxazole compound represented by 21 includes a pyrrolopyrrole compound represented by the general formula (1), an oxazole compound represented by the above general formula (2), and a binder resin. a single-layer photosensitive layer containing at least a pyrrolopyrrole compound represented by the general formula (1), and an oxazole compound represented by the above general formula (2) and a binder resin. It may be any laminated type photosensitive layer in which a charge transport layer containing the above is laminated.

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, ethylene-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 Examples include various polymers such as resins, polyether resins, phenol resins, and photocurable resins such as epoxy acrylate. 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 oxazole compound represented by the general formula (21), and the binder resin in the single-layer photosensitive layer is not particularly limited. It can be selected as appropriate depending on the characteristics of the photographic photoreceptor, but 2 to 20 parts by weight, especially 3 to 15 parts by weight of a pyrrolopyrrole compound per 100 parts by weight of the binder resin.
Parts by weight of the oxazole compound are preferably 40 to 200 parts by weight, particularly 50 to 100 parts by weight. If the amount of the pyrrolopyrrole compound and oxazole compound is less than the above amount, not only the sensitivity of the photoreceptor will not be sufficient, but
Residual potential increases. 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
Those having a thickness of 0 to 50μ, particularly 15 to 25μ 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 general formula (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 700 parts by weight, particularly 10 to 500 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 700 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.

Further, the ratio of the oxazole compound represented by general formula (2) and the binder resin in the charge transport layer can be set as appropriate, but the proportion of the oxazole compound represented by the general formula (2) to 100 parts by weight of the binder resin is 10 to 500 parts by weight. parts, especially 25 to 200 parts by weight. If the amount of the oxazole 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, but preferably has a thickness of about 2 to 100 μm, particularly about 5 to 30 μm.

Further, the charge generation layer may contain the oxazole compound as a charge transport material together with the pyrrolopyrrole compound as a charge generation material; in this case,
The ratio of the pyrrolopyrrole compound, oxazole compound, and binder resin in the charge generation layer is set as appropriate;
It is preferable that the pyrrolopyrrole compound, the oxazole compound, and the binder resin are comprised in the same proportions as in the single-layer type photosensitive layer. Further, the charge generation layer having the above-mentioned ratio is formed to have an appropriate thickness, but the thickness is 0.1 to 50.
It is formed on the order of μm.

The single-layer type photosensitive layer is prepared by preparing a photosensitive layer dispersion containing the pyrrolopyrrole compound, oxazole compound, binder resin, etc., and applying the dispersion to the conductive base material.
It can be formed by drying or curing. In addition, for the laminated photosensitive layer, a charge generation layer dispersion containing a pyrrolopyrrole compound and a binder resin, and a charge transport layer coating solution containing the oxazole compound and a binder resin are prepared respectively. , sequentially applied to a conductive substrate,
It can be formed by drying or curing.

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, and halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene. , ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether,
Examples of various solvents include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formamide, and dimethyl sulfoxide, which may be used singly 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.

Further, the above-mentioned dispersion liquid etc. can be prepared using a conventional method such as a mixer, a ball mill, a paint shaker sand mill, an attritor, an ultrasonic disperser, etc., and the obtained dispersion liquid etc. The electrophotographic photoreceptor of the present invention can be obtained by applying it to a base material and removing the solvent by heating.

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 about 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 mixed solution of the binder resin and additives such as deterioration inhibitors to a film thickness of 0.1 to 10 I#, 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 general formula (
A pyrrolopyrrole compound represented by 1) and the general formula (2
), 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.

<Example> The present invention 7 will be described in more detail below based on Examples.

Using the following pyrrolopyrrole compound as a charge generating material and the following oxazole compound as a charge transporting material, an electrophotographic photoreceptor having a laminated photosensitive layer or a single layer photosensitive layer was prepared as follows.

Pyrrolopyrrole compounds The above pyrrolopyrrole compounds are indicated by the following abbreviations in Table 2.

A2 1,4-dithioketo-3,6-diphenylpyrrolo[
3,4-cl pyrrole B: 1,4-dithioketo-3,6-di(4-tolyl)pyrrolo[3,4-cl pyrrole C: l, 4-dithioketo-3,6-di(4-methoxyphenyl) ) Pirolo [3,4
-c] Copyrrole: 1,4-dithioketo-3,6-dinitylvirolo[3
,4-cl Virol E: N,N'-diethyl-1,4-dithioketo-3,6
-tert-butylpyrrolo[3,4-c copyrrole F: 1,4-dithioketo-3,6-distearylpyrrolo[3,4-cl pyrrole Examples 1 to 8 (Preparation of laminated electrophotographic photoreceptor) Charge A charge consisting of 10 parts by weight of the above-mentioned pyrrolopyrrole compound shown in Table 2 as a generating material, 10 parts by weight of vinyl chloride-vinyl acetate copolymer (manufactured by Sekisui Chemical Co., Ltd., trade name Kosuretsuku C), and a predetermined amount of tetrahydrofuran. A generation layer coating solution was prepared, and the resulting coating solution was applied onto an aluminum sheet and heated at 100° C. for 30 minutes to form a charge generation layer having a thickness of 0.5 μm.

Next, a charge transport layer was formed using the oxazole compound shown in Table 2 as a charge transport material. That is, 7 parts by weight of the oxazole compound shown in Table 2, 10 parts by weight of bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name PCZ), and a predetermined amount of benzene were mixed and dissolved to form a charge transport layer coating solution. At the same time, a charge transport layer having a thickness of 201 tl was formed by coating the charge generation layer on the charge generation layer and heating and drying, thereby producing an electrophotographic photoreceptor having a laminated photosensitive layer.

Comparative Examples 1 to 2 A laminated photosensitive layer was prepared in the same manner as in the above Example, except that compounds represented by the following general formulas (11 to [11)] were used in place of the oxazole compound in Example 1. An electrophotographic photoreceptor having the following structure was fabricated.

Comparative Example 3 In place of the pyrrolopyrrole compound of Example 1, N,N'-bis(3,5-dimethylphenyl)perylene-3,4,9°10-tetracarbodiimide represented by the following general formula (2) mN in the same manner as in implementation fN1 except that .
An electrophotographic photoreceptor having a molded photosensitive layer was produced.

Evaluation Test 1 In order to examine the charging characteristics and photosensitive characteristics of the electrophotographic photoreceptors obtained in Examples 1 to 8 and Comparative Examples 1 to 3, an electrostatic copying paper tester (manufactured by Kawaguchi Denki Co., Ltd., 5P-428C2) was used. The electrophotographic photoreceptors of each of the Examples and Comparative Examples were negatively charged by performing corona discharge under the condition of -6, OKV. In addition, the initial surface potential of each photoreceptor VS, I
), m was measured, and the surface of the photoreceptor was exposed to light using a 10 lux tungsten lamp, and the surface potential V
s, p.

Find the time until it becomes l/2, and find the half-decreased exposure amount El/2
(μJ/aA) was calculated. Furthermore, the surface potential 0.15 seconds after exposure is determined as the residual potential Vr, p, (
V).

Table 2 shows the charging characteristics, photosensitive characteristics, etc. of the multilayer electrophotographic photoreceptors obtained in the above Examples and Comparative Examples.

In addition, in Table 2, the conjugated compounds of Examples 1 to 8 are
It is shown using the compound number in the table.

(Hereinafter, blank space) Examples 9 to 11 (Preparation of single-layer electrophotographic photoreceptor) 3 parts by weight of the pyrrolopyrrole compound shown in Table 3, 100 parts by weight of the oxazole compound, bisphenol Z type polycarbonate (described above) 100 parts by weight and a predetermined amount of tetrahydrofuran were charged into a Beaufremir and mixed and dispersed for 24 hours to prepare a dispersion for a single-layer electrophotographic photosensitive layer. The above dispersion was applied onto an alumite-treated aluminum plate, and 1
It was dried at 30° C. for 30 minutes to produce an electrophotographic photoreceptor having a single-layer type photosensitive layer with a thickness of 18 μm.

Comparative Example 4 An electrophotographic photosensitive material having a single-layer type photosensitive layer was produced in the same manner as in Example 9, using a compound represented by the above general formula (I[) in place of the oxazole compound of Example 9. The body was created.

Comparative Example 5 Electrophotographic photosensitive material for blinding a single-layer type photosensitive layer was produced in the same manner as in Example 9, except that a perylene compound represented by the above general formula was used in place of the pyrrolopyrrole compound in Example 9. The body was created.

Evaluation Test 2 In order to investigate the charging characteristics and photosensitive characteristics of the electrophotographic photoreceptors obtained in Examples 9 to 11 and Comparative Examples 4 to 5, the electrophotographic photoreceptors were heated to +6. The electrophotographic photoreceptors of each of the Examples and Comparative Examples were positively charged by performing corona discharge under OKV conditions. /aA), residual potential v, r, p, (V) were determined.

Table 3 shows the charging characteristics, photosensitive characteristics, etc. of the single-layer electrophotographic photoreceptors obtained in the above Examples and Comparative Examples.

In addition, in Table 3, the oxazole compounds of Examples 9 to 11 and Comparative Example 5 are indicated using compound numbers in Table 1.

(Hereinafter, blank space) From Table 2 and Table 3, Examples 1 to 8 and Example 9
It can be seen that the electrophotographic photoreceptors of Nos. 1 to 11 have higher sensitivity and lower residual potential than the electrophotographic photoreceptors of Comparative Examples 1 to 3 and Comparative Examples 4 to 5, respectively. It is also seen that the electrophotographic photoreceptors of Examples 1 to 11 all have good charging characteristics.

<Effects of the Invention> As described above, according to the electrophotographic photoreceptor of the present invention, the photosensitive layer contains a pyrrolopyrrole compound represented by the above general formula (1) and an oxazole represented by the above general formula (2). Since it contains a series compound, it has the effect 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 substrate, wherein the photosensitive layer contains a pyrrolopyrrole compound represented by the following general formula (1) and a pyrrolopyrrole compound represented by the following general formula (2). ) An electrophotographic photoreceptor comprising an oxazole 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,
Represents an aryl group, an aralkyl group, or a heterocyclic group that 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 that may have a substituent. Indicates the group. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^5 and R^6 are the same or different and represent a lower dialkylamino group which may have a substituent, and R^7 is a hydrogen atom. , halogen atom, lower alkyl group,
Indicates a lower alkoxy group. ) 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, an alkyl group, an alkoxy group The electrophotographic photoreceptor according to claim 1, wherein the substituent is a substituent selected from the group consisting of a dialkylamino 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,
2. 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.