JPS63313164A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To shorten dispersion time, to obtain a stable coating solution, to enhance sensitivity of a photosensitive body, and to retain potential stability even at the time of successive uses by using specified 2 kinds of pigments as an electric charge generating material. CONSTITUTION:The electrophotographic sensitive body is formed by laminating on a substrate a charge generating layer containing both of the pigments represented by formulae I and II, and a charge transfer layer. In formula I, each of A1 and A2 is a coupler residue having a phenolic OH group; R is H or an optionally substituted alkyl, such aralkyl, such aryl, or such acyl; and each of Ar1 and Ar2 is optionally substituted arylene, and in formula II, each of A3 and A4 is a coupler residue having a phenolic OH group; R is H or an optionally substituted alkyl, such aralkyl, such aryl, or such acyl; Ar3 is optionally substituted arylene or such a heterocyclic group; and Ar4 is an optionally substituted pyridine-diyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor having a charge generation layer and a charge transport layer.

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. , anthracene, pyrazolines, oxadiazoles, hydrazones, polyaryl alkanes, and other low-molecular organic photoconductors, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic bovine pigments, perylene pigments, indigo dyes, Organic pigments and dyes such as squaric acid methine dyes are known. # Organic pigments and dyes that have photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded, so there are many photoconductive materials. Conductive organic pigments and dyes have been proposed.

For example, US Pat. No. 4,123,270, US Pat. No. 4,247,614, US Pat. No. 4,251,613, US Pat. No. 4,251,614, US Pat. No. 4,256,821, US Pat. No. 4,260,672.
US Pat. No. 4,268,596, US Pat. No. 4,278,747, US Pat. No. 4,29362
8, an electrophotographic photoreceptor using a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer is known.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide an extremely highly productive and inexpensive photoreceptor.
Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by selecting organic pigments and dyes.

A-layer type photoreceptors, which are obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation substance, are more sensitive than other single-layer photoreceptors due to increased sensitivity and residual potential after durability tests. Although it was advantageous, it was still not at a sufficient level.

In addition, when producing by coating, a coating liquid in which organic pigments and binders are dispersed in an organic solvent is often used. Many pigments require long-term dispersion in a container, and some coating solutions tend to aggregate within a few days. Ta.

[Problems to be Solved by the Invention] An object of the present invention is to improve the above-mentioned drawbacks, to provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test, and to perform dispersion in a short time. can, and
The object of the present invention is to provide a stable coating solution that does not undergo changes over time such as aggregation.

Means and operation for solving the problem [r] The present invention provides a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, in which the charge generation layer has the general formula (1
) % Formula % (1) (In the formula, A1 and A2 represent a coupler residue having a phenolic OH group, and R is a hydrogen atom or an alkyl group which may have a substituent, aralkyl, (, aryl group or represents an acyl group, Ar1 and Ar2 represent an arylene group which may have a substituent; represents a coupler residue having a group, R represents a hydrogen atom or an alkyl group, an aralkyl group, an aryl group, or an acyl group which may have a substituent, and Ar3 represents an arylene group or a hetero group which may have a substituent. The electrophotographic photoreceptor is composed of an electrophotographic photoreceptor characterized in that it also contains a pigment represented by (representing a cyclic group, Ar4 represents a pyridinediyl group which may have a substituent).

In the laminated electrophotographic photoreceptor of the present invention, the charge generation layer contains as much charge generation material as possible in order to obtain sufficient absorbance, and in order to efficiently inject the generated charge carriers into the charge transport layer. 1 thin layer, e.g. 10μ
Hereinafter, it is preferable to use an Ft film layer having a thickness of 0°O1 to 1°. This means that most of the incident light is absorbed by the charge generation layer, generating a large number of charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection.

The charge generating substance used in the present invention has the general formula (1) (% formula %) (wherein A1 and A2 represent a coupler residue having a phenolic OHI, and R may have a hydrogen atom or a substituent. Indicates a good alkyl group, aralkyl group, aryl group or acyl group, Arl and Ar2 are substituted 7.tf
% formula (2) (where A3 and A4 represent a coupler residue having a phenolic OH group, and R represents a hydrogen atom). Alkylno, (, aralkyl group, aryl group, or acyl group that may have an atom or a substituent, Ar3 represents an arylene group or a heterocyclic group that may have a substituent, and Ar4 represents an arylene group or a heterocyclic group that may have a substituent. pyridinediyl group).

In particular, the polarity of the pigment represented by general formula (1) can be changed by introducing an alkyl group, an aralkyl group, an aryl group, or an acyl group as a substituent R to the nitrogen atom of the diarylamine that forms the backbone of the disazo pigment. This results in improved charge carrier generation efficiency and/or charge carrier transportability, resulting in improved sensitivity as a photoreceptor and ensured potential stability during long-term use.

By the presence of the pigment represented by general formula (1) in the charge generation layer, it is possible to create a highly sensitive photoreceptor,
A stable potential is ensured regardless of the previous history of the photoreceptor.

(Hereinafter, in the margin) Representative examples of the pigment represented by the general formula (1) are listed below.

An exemplary format includes the disazo pigment Al-NmN-Arl-N-Arz-NmN-Az(
In the formula, AI and A2 represent a coupler residue having phenolic OH3, R represents a hydrogen atom or an alkyl group, an aralkyl group, an aryl group, or an acyl group which may have a substituent, and Ar1 and Ar2 are substituted (Indicates an arylene group which may have a group) Only the changed portions in the arylene group (indicates an arylene group which may have a group) are described.

Pigment example (1) Ar1, Ar2: + Pigment example (2) , R: -(H.

Ar1. Ar2:+ Pigment example (3) Cut Ar1, Ar2: + Pigment example (4) Ar1, Ar2: +@)- Face 1 example (5) C Ar1. Arz:+ Pigment example (6) Arc, Ar2: building Pigment example (7) Arl　, Ar2　:+ Pigment example (8) Arl, A rz:+ Pigment example (9) r , R: -CHy Ar1. Ar2: Building Pigment example (lO) R: -OH.

Pigment example (l l) R: -CH3 Ar1, Ar2 knee o- Pigment example (12) N R: -C) I3 Arc, Ar2: Pigment example (13) R: -OH5 A rl, A rz: (needle Pigment example (14) R: -0H3 Arl, Ar2: building Pigment example (15) R: -(H.

A rl, A rz:+ Pigment example (1B).

R: -CH3 Ar1, Ar2: (warm Pigment example (17) Ar1.　A　rz　：　-) Pigment example (18) A rl, A rz: (death Face) Example (19) Arl　, Ar2　:+ Pigment example (2o) R: -CHa Ar1, Ar2: + Pigment example (21) R:　　　-C)! .

Arl, Ar2 knee @- Pigment example (22) R: -C) I3 Ar1. Ar2:+ Pigment example (23) R: -083 Ar1, Ar2 knee o- Pigment example (24) R: -0H3 Ar1. Ar2 knee o- Pigment example (25) Arl, Ar2: building Pigment example (26) Q Arl　, Ar2　:+ Pigment example (27) ff Ar1, Ar2: (To Pigment example (28) R: -C)l.

Ar1, Ar2: building Pigment example (29) t Ar1. Arz knee o- Pigment examples (30) R: -0H3 Arl, Ar24 Pigment example (31) R: -CH5 Arl　, Ar2　:+ Pigment example (32).

C.I.

Arl　, Ar2　:+ Pigment example (33) Ar1, Ar2: + Pigment example (34) CH R: -CH.

A rl, A r2: (T Pigment example (35) Arl　, Ar2　:(X Pigment example (36) CH R: -C)+3 Arl　, Ar2　:+ Pigment example (37) Arl　, Ar2　:(X Pigment example (38) R: -C+H5 Ar1. Ar2: building Pigment example (39) R: -c, o, o.

Arl, Ar2.9 Pigment examples (40) Pigment example (41) Ar1, Arz: (X Pigment example (42) R: -C)! 1go CN Ar1, Ar2 knee @)- Pigment example (43) Ar1. Arz:+ Pigment example (44) Arl　, Ar2　:+ Pigment example (45) l Ar1, A r2:+ Pigment example (46) R-■ Arl　, Ar2　:+ Pigment example (47) Arl　, Ar2　:+ Pigment example (48) Ar1, Ar2: + Pigment example (49) Ar1, Ar2;+ Pigment examples (50) Arl, Ar2: building Pigment example (51) Ar1. Ar2: Pigment example (52) Arl　, Ar2　:+ Pigment example (53) J Arl, Ar2: building Pigment example (54) Pigment example (55) Pigment example (56) Pigment example (57) R: II to -.

Pigment example (58) R: -CH3 Pigment example (59) I Pigment examples (60) R: -CB.

Pigment example (61) Pigment example (62) r Arl　, Ar2　:+ Pigment example (63) Pigment example (64) R knee C-CH.

Ar1, Arz:+ Pigment example (65) Ar1, Ar2: + Pigment example (66) R? Arl　, Ar2　:+ Pigment example (67) υ Arl, Ar24 Pigment example (68) Pigment example (69) Ar1, Ar2: building Pigment examples (70) Arl, Ar2, building Pigment example (71) Ar1. Ar2:+ Pigment example (72) Arl　, Ar2　:’+ Pigment example (73) , R Nie Zeng-(H3 Ar1. Ar2 knee o- Pigment examples (74) Pigment example (75) Arl　, Ar2　:4 Pigment examples (76) 1 case of facial nails (77) , R: =C+Hs(S) Ar1. Ar2:+ Pigment example (78) R: -CHy Ar1. Ar2: (S Pigment examples (79) I'T.

R:H Arl, Ar2:+ Pigment Example (80), R:H Ar1, Ar2:+ Pigment Example (81) R: -CH3 Ar1. Ar2:+ Pigment example (82) Ar1, Ar2:+ Pigment example (83) R:H Ar1. Ar2 Knee@) - Pigment Example (84) Arl, Ar2: Sha Pigment Example (85) Ar1. Ar2: Pigment example (86) R: I+ Arl, Ar2 Ni@)- Pigment example (87) Pigment example (88) R; H A rl, Ar2: + Pigment example (89) l R: -CH3 Ar4, Ar2 ni o = Pigment Example (90) These disazo pigments have Al, A2 in the general formula (1)
By arbitrarily selecting the type of coupler shown in
It is possible to change the spectral sensitivity of a photoreceptor using this pigment.

For example, pigment examples (7), (74), (76), (83)
etc., have sensitivity in the long wavelength region of 750 nm or more, but
(1), (2), (34), (79) etc. are 750 r
It has no sensitivity in the long wavelength region of am or more.

The pigment represented by general formula (1) is prepared by adding 7non, methyl ethyl ketone, dioxane, methyl cellosolve, DMF,
Heat treatment or milling treatment using an organic solvent such as benzene, nitrobenzene, dichloromethane, inpropanol, or tetrahydrofuran often improves the stability after dispersion, especially for pigments that are sensitive to long wavelength regions. By performing the above treatment, it is also possible to change the crystal structure and shift the sensitivity range to the longer wavelength side.

Pigments that have undergone pretreatment such as heat treatment or milling treatment tend to have poor dispersion properties and become difficult to disperse.

Moreover, although coating liquids prepared by dispersion are less prone to agglomeration than unpretreated pigments, most dispersions will agglomerate if left for several weeks.

In order to shorten the dispersion time and obtain a stable coating solution while maintaining the electrophotographic properties as described above, the pigment represented by the general formula (2) is added to the pigment represented by the general formula (1). This is achieved by

Examples of things that can be added to the pigment represented by general formula (1) include azo pigments such as sudanredo, guiample, and dienas green B, quinone pigments, perylene pigments, and indigo pigments such as indigo and thioindigo. Even if this pigment is added, it is not possible to shorten the dispersion time or obtain a stable coating solution.

The above-mentioned effects can be significantly exhibited by the pigment represented by the general formula (2).

The amount to be added varies depending on the type of pigment represented by general formula (1), but 0 parts by weight of pigment represented by general formula (1) is added.
．． If it is less than 0.01 part by weight, no effect will be observed, and if it is added in a ratio greater than 1 part by weight, the electrophotographic properties of the pigment represented by -IIQ formula (1) will be reduced. Preferably, if it is 0.4 parts by weight or less, it will hardly cause any adverse effects on photographic properties, and preferably, if it is less than 0.4 parts by weight, Further, if the amount is in the range of 0.4 to 0.1 parts by weight, remarkable effects can be achieved in terms of dispersibility and stability.

The timing of adding the pigment represented by the general formula (2) is determined by the general formula (1).
) It depends on the type of pigment, but it is generally effective to add it before dispersion.

If added before dispersion, even pigments that require a long dispersion time can be dispersed in a considerably short time.

However, among the pigments represented by general formula (1), pigments with particularly good dispersibility are those represented by general formula (1) and general formula (2).
A highly stable coating solution can also be obtained by dispersing each of the pigments represented by the following and mixing the respective dispersions.

The first effect of adding the pigment represented by the general formula (2) to the pigment represented by the general formula (1) is to improve the dispersion properties shown in the shortening of the dispersion time and to stabilize the prepared coating liquid. The second effect is that by selecting the pigment represented by the general formula (2), it is easy to improve the problems in characteristics that occur with the pigment represented by the general formula (1).

Characteristics that should be improved include an increase in bright area potential when charging and exposure are continuously repeated, and a decrease in dark area potential when the same process is repeated.

Furthermore, what kind of structure of the pigment is effective depends largely on the characteristics and structure of the pigment represented by the general formula (1) actually used.

Representative examples of the pigment represented by general formula (2) are listed below.

An exemplary format is a disazo pigment A3-N=N-Ar3-N-Ar4-N-N-Av (where A3-A4 represents a coupler residue having a phenolic OH group, R is a hydrogen atom, a substituted An alkyl group, an aralkyl group, an aryl group, or an acyl group that may have a substituent, Ar3 represents an arylene group or a heterocyclic group that may have a substituent, and Ar4 may have a substituent. pyridinediyl group) are described.

Pigment example (91) R: -C84 Ar3: + Ar4: Lower pigment example (92) I R: ll:H3 Pigment example (93) I Pigment example (94) Ar3: -YAr4: 9 Pigment example (95) ) Pigment example (96) R:H Ar3. Ar4: + Pigment example (97) Pigment example (98) Pigment example (99) Pigment example (100) JH R:H Pigment example (l O1) Pigment example (102) Pigment example (103) n+-1 R: -CH C) Is r r The charge generating layer can be formed by coating the above-mentioned pigment and, if necessary, a charge transporting substance together with a suitable binder (or without a binder) on a support, or by vacuum deposition. It can be obtained by forming a vapor-deposited film using an apparatus.

The binder that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.)
, polycarbonate, polyester, phenoxy resin,
polyvinyl acetate, acrylic resin, polyacrylamide,
polyamide, polyvinylpyridine, cellulose resin,
Examples include insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer or undercoat layer described later.

Specific organic solvents include methanol, ethanol,
Alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N
, amides such as N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether;
Esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. aromatics.

Dispersion is carried out by a conventional method such as a sand mill, ball mill, homomixer, or homogenizer.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coach ink method, a roller coach ink method, or a curtain coating method. For drying, it is preferable to dry it by heating after touching it at room temperature.

Heat drying can be carried out at 30 to 200''C for 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, receives and receives charge carriers injected from the charge generation layer in the presence of an electric field, and transfers these charge carriers to the surface. It has the ability to transport up to At this time, this charge transport layer may be laminated on the charge generation layer,
It may also be layered underneath.

It is preferable that the charge transport material in the charge transport layer is substantially insensitive to the wavelength range of electromagnetic waves to which the above-mentioned charge generation layer is sensitive. It encompasses a broad definition of ray that includes .

When it coincides with or overlaps with that of the charge transport layer, the charge carriers generated in both trap each other, resulting in a decrease in sensitivity.

The charge transport material used in the present invention may be any general charge transport material used in laminated electrophotographic photoreceptors, such as pyrazoline compounds, hydrazone compounds, stilbene compounds, triphenylamine compounds,
Examples include benzidine compounds and oxazole compounds.

To form a charge transport layer containing a charge transport substance, a film can be formed by selecting an appropriate binder.

Resins that can be used as binders include, for example, acrylic resins, polyarylates, polyesters, polycarbonates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers, polyvinyl butyral, polyvinyl formal, polysulfones, polyacrylamides, polyamides, chlorinated rubbers, etc. and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

The charge transport layer has a limit in its ability to transport charge carriers, so it cannot be made thicker than necessary. Generally, the thickness is 5 to 40 g, but the preferable range is .8 to 25 g.

When forming the charge transport layer by coating, an appropriate coating method as described above can be applied.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a support having electrical conductivity, that is, a conductive support.

As the conductive support, materials that have conductivity themselves, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum, can be used. In addition, plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., as well as carbon blur, silver particles, etc., together with a suitable binder. A support obtained by coating plastic or the metal support described above, a support obtained by impregnating plastic or paper with conductive particles, a plastic containing a conductive polymer, or the like can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive support and the photosensitive layer.

The undercoat layer includes casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic ugly copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon,
(alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 to 40. , preferably 0.1-3
uL is appropriate.

When using a photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material in the charge transport layer is an electron transport material, the surface of the charge transport layer is positively charged. When exposed to light after charging, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and a decrease in contact with the unexposed area. An electrostatic contrast occurs between them.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner.

This can be directly placed, or the toner image can be transferred to paper or plastic film and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, and then visually imaged and fixed. The type of developer, developing method, and fixing method may be any known developer or known method, and are not limited to a specific developer or method.

On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged, and the surface of the charge transport layer must be negatively charged. l! During post-exposure, the positive charge generated in the charge generation layer is injected into the charge transport layer in the exposed area, and then reaches the surface and neutralizes the negative charge, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area. occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used.

The electrophotographic photoreceptor of the present invention is susceptible to deterioration due to ultraviolet rays, ozone, etc., dirt due to oil, etc., scratches due to metal chips, etc., and damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, and cleaning members. A protective layer may be further provided on the charge generation layer or the charge transport layer for the purpose of preventing scratching.

Silence on the protective layer? ! ! In order to form a latent image, it is desirable that the surface resistivity is 10 11 Ω or more.

The protective layer is made of a resin such as polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, polyamide, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, etc., in a suitable organic solvent. The photosensitive layer can be formed by coating a solution dissolved thereon on the photosensitive layer and drying it. Additionally, additives such as ultraviolet absorbers can be added to the resin liquid.

The thickness of the protective layer generally ranges from 0.05 to 20 mm, preferably from 0.2 to 5 mm.

[Example] Example 1 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 m of water) was coated on an aluminum cylinder and dried to a coating amount of 1.0 g 7 m2
A subbing layer was formed.

Next, 1.0 parts by weight of the charge-generating substance of Pigment Example (74), 0.4 parts by weight of the charge-generating substance of Pigment Example (99), and 1 part by weight of butyral resin (trade name: Kosuretsu BM-2, manufactured by Mikki Kagaku ■) and 30 parts by weight of cyclohexanone were dispersed for 4 hours using a sand mill disperser using glass beads having a diameter of 1 mm. After separating the glass beads, 60 parts by weight of tetrahydrofuran was added, and this was coated on the previously formed subbing layer by a dip-neating method, and dried to form a charge generation layer.
The thickness was 0.3 tiles.

Next, p-diethylaminobenzaldehyde-N-7enyl-N-α-naphthylhydrazone 1 was used as a charge transport substance.
Part by weight, styrene-methacrylic acid copolymer (trade name M
Parts of lfi (S200, manufactured by Seitetsu Kagaku ■) and 6 parts by weight of monochlorobenzene were mixed and dissolved by stirring with a stirrer. This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The film thickness was 12 l.

A corona discharge of 15 KV was applied to the electrophotographic photoreceptor thus prepared. The surface potential at this time was measured (initial potential Vo).

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (Vs).

Sensitivity was evaluated by measuring the amount of exposure (E 1 /21 ux, 5 ec) required to attenuate the potential 5 after dark decay to 1/2.

Show the results.

vo knee 830V, V5 knee 740V, E 1
/ 2: 1, 2 21ux, secNext, this photoreceptor was placed in a Canon FC-5 model compound machine,
Two thousand sheets of paper were passed under 20'C560%RH. After this, the surface potential was measured in the same manner as above. Show the results.

vo knee 820V, vs knee 700V, E 1/
2: l, l 51ux, sec Comparative Example 1 Among the charge generating substances used in Example 1, pigment example (
Example 1 except that 1.4 parts by weight of only the pigment 74) was used.
A photoreceptor was prepared in exactly the same manner as described above, and the characteristics of the photoreceptor were measured. Show the results.

Vo knee 860V, Vs knee 800V, El/2
:1.40 sentences u! , Sec In addition, the paper was passed through an FC-5 type copying machine in the same manner, and the surface potential was measured after this. Show the results.

Vo knee 865V, v5 knee 820V, E 1 /2
: 1, 62 Jlux, sec Examples 2 to 7 Pigment examples of charge generating substances used in Example 1 (74
), pigment examples (2), (7), (76), (81
), (86), and (8) were used to prepare electrophotographic photoreceptors in the same manner as in Example 1, and the characteristics of each photoreceptor were measured.

Further, after the above characteristic evaluation, the paper was passed through an FC-5 copying machine in the same manner as in Example 1, and the surface potential was then measured. Show the results.

2 860 845 1.753 850
810 1.234 850 800
1.005 830 760 0.606
840 775 0.887 840 8
15 2.912 850 820 2.2
13 860 810 1.814
800 700 1.235
520 430 0.506
680 600 0.837
910 900 4.51 Comparative Examples 2 to 7 Pigment examples of charge generating substances used in Comparative Example 1 (74
), pigment examples (2), (7), (76), (81
), (86), and (8), electrophotographic photoreceptors were prepared in the same manner as in Comparative Example 1, and the characteristics of each photoreceptor were measured.

Further, after the above characteristic evaluation, the paper was passed through an FC-5 copying machine in the same manner as in Comparative Example 1, and the surface potential was then measured. Show the results.

2 860 845 1.753 850
810 1.234 850 800
1.005 830 760 0.606
840 775 0.887
840 815 2.912
850 B20 2.213
860 810 1.814
800 700 1.235 5
20 430 0.506 6
80 600 0.837 9
10 900 4.51 From the results of the above Examples and Comparative Examples, general formula (2) was added to the pigment represented by general formula (1).
It is recognized that even if the pigment represented by formula (1) is added and dispersed, there is no adverse effect on the effective electrophotographic properties of the pigment represented by general formula (1).

In Examples 1 to 7 and Comparative Examples 1 to 7, the particle sizes of the pigments immediately after dispersion are shown below.

For measurement, ■ CAPA700 particle size distribution manufactured by Horiba, Ltd.
11 was used.

'(Sezi ・,-, 1 grain'- 10,2010,41 20,2120,33 30,2630,35 40,1640,32 50,1350,30 60,2560,45 70,2470,32 Example 1 As described above, the pigment particle size in Comparative Examples 1 to 7 is considerably larger than that in Comparative Examples 1 to 7.

That is, it is recognized that for the same dispersion time, by adding the pigment of general formula (2), it is possible to disperse into fine particles.

Comparative Examples 8 to 14 Under the dispersion conditions of Comparative Examples 1 to 7, only the dispersion time was changed, and dispersion was carried out until the pigment particle size became 0.20 l or less. The time required for this is shown below.

Next, 500 cc of each coating solution in Examples 1 to 7 and Comparative Examples 8 to 14 was taken, and after rotating on a ball mill for 100 hours, the particle size of each pigment was measured. Show the results.

--111 0.42 8 0.792 0.33
9 0.583 0.48 10
0.814 0.27 11 0.775
0.18 12 0.656 0.35
13 0.717 0.39 14 0.6
5 From the above results, it is recognized that the addition of the pigment of general formula (2) causes less grain enlargement.

Examples 8 to 10 Pigment examples of charge generating substances used in Example 1 (99
Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that pigment examples (95), (92), and (96) were used in place of pigments (95), (92), and (96), and the characteristics of each photoreceptor were measured. Further, after the above characteristic evaluation, the paper was passed through an FC-5 copying machine in the same manner as in Example 1, and the surface potential was then measured. Show the results.

8 850 770 1.219 840
780 1.3010 830 775
1.318 830 755 1.259
840 775 1.4310 830
765 1.38 - From Narushima 1 of the above example, even if the type of pigment represented by general formula (2) is changed, Examples 1 to 1.
Similarly to 7, it is recognized that the effective electrophotographic properties of the pigment represented by formula (1) are not deteriorated.

As is known from the examples above, in terms of potential, the general formula (
It is clear that the addition of the pigment shown in 2) has almost no effect on the sensitivity.

Further, as is clear from comparing the Examples and the Comparative Examples, the Examples have less potential fluctuation after durability than the Comparative Examples, and can provide stable images.

Furthermore, when viewed as a coating liquid, as is clear from Comparative Examples 8 to 14, improvements in dispersibility were observed, and it was possible to obtain microparticles in a short period of time. However, it is recognized that the particles increased only about half of that of the comparative example, resulting in a coating liquid with improved liquid stability.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has remarkable effects such as high sensitivity and extremely low residual potential even after durability due to the use of two specific types of pigments as charge generating substances. Furthermore, the dispersion time can be shortened when preparing the charge generation layer coating solution.
Characterized by the effect of stabilizing the dispersed liquid without agglomeration, which contributes to productivity.

Claims (5)

[Claims] (1) In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer has the general formula (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) (In the formula, A_1 and A_2 represent coupler residues having a phenolic OH group, R represents a hydrogen atom or an alkyl group, an aralkyl group, an aryl group, or an acyl group that may have a substituent, and Ar_1 and Ar_2 represents an arylene group that may have a substituent, and general formula (2) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (2) (In the formula, A_3 and A_4 are phenolic OH groups. R represents a hydrogen atom or an alkyl group, an aralkyl group, an aryl group, or an acyl group that may have a substituent, and Ar_3 represents an arylene group or a heterocyclic ring that may have a substituent. An electrophotographic photoreceptor characterized in that it also contains a pigment represented by the following formula (Ar_4 represents a pyridinediyl group which may have a substituent). (2) The ratio of the pigment represented by general formula (1) to the pigment represented by general formula (2) in the charge generation layer is represented by general formula (2) with respect to 1 part by weight of the pigment represented by general formula (1). Pigment is 0.4
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is mixed in an amount of g parts by weight or less. (3) The electrophotographic photoreceptor according to claim 1 or 2, wherein the pigment represented by general formula (1) is a disazo pigment having the following structural formula. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (4) In the pigment represented by general formula (1), A_1 in the formula
, A_2 are different types of pigments, the electrophotographic photoreceptor according to claim 1 or 2. (5) The electrophotographic photoreceptor according to claim 1, 2, or 4, wherein the pigment represented by general formula (1) is a pigment represented by general formula (3) below. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(3)