JPH0422261B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a photoreceptor for electrophotography. Prior Art Conventionally, there have been inorganic photoreceptors for electrophotography, such as those using selenium and its alloys, or photoreceptors with dye-sensitized zinc oxide dispersed in a binder resin, and organic photoreceptors. In the one of
A typical example is one using a charge transfer complex of 2,4,7-trinitro-9-fluorenone (hereinafter referred to as TNF) and poly-N-vinylcarbazole (hereinafter referred to as PVK). but,
Although these photoreceptors have many advantages, it is also true that they also have various disadvantages. For example, the currently widely used selenium photoreceptor has difficult manufacturing conditions and high manufacturing costs, is difficult to process into a belt shape due to its lack of flexibility, and is sensitive to heat and mechanical shock. Therefore, care must be taken when handling it. Zinc oxide photoreceptors are low in cost because they can be manufactured by applying inexpensive zinc oxide to a support, but they generally have low sensitivity and poor surface smoothness, hardness, tensile strength, and abrasion resistance. It has mechanical disadvantages such as durability, and there are many problems with durability as a photoreceptor for plain paper copying machines that are usually used repeatedly. Also, TNF and PVK
Photoreceptors using charge transfer complexes with
It is unsuitable as a photoreceptor for high-speed copying machines. In recent years, extensive research has been carried out to eliminate the drawbacks of these photoreceptors, and in particular, various organic photoreceptors have been proposed. Among these, there is a layer containing a substance that generates charge carriers when irradiated with light (hereinafter referred to as charge generation material), and a layer containing a substance (hereinafter referred to as charge generation layer) that generates charge carriers and transports them (hereinafter referred to as charge generation layer). A layer mainly composed of a charge transport material (hereinafter referred to as a charge transport layer)
Laminated type photoreceptors consisting of these materials are attracting attention as photoreceptors for plain paper copiers because they generally have higher sensitivity and stable charging properties than conventional organic photoreceptors. Some of them are in practical use. Conventional laminated photoreceptors of this type include: (1) one in which a thin layer of a perylene derivative vacuum-deposited is used as a charge generation layer and an oxadiazole derivative is used as a charge transport layer (U.S. Pat. No. 3,871,882);
(2) Using a thin layer formed by coating an organic amine solution of chlordiane blue as the charge generation layer,
Those using a hydrazone compound in the charge transport layer (see Japanese Patent Publication No. 55-42380) are known. However, it is true that conventional laminated photoreceptors of this type have many advantages, but also have various drawbacks. The photoreceptor using the perylene derivative and oxadiazole derivative shown in (1) has a high manufacturing cost because its charge generation layer is formed by vacuum deposition. Further, even if there is no practical problem, there are problems such as insufficient sensitivity as a photoreceptor for higher speed copying machines. The photoreceptor using chlordiane blue and hydrazone compound shown in (2) requires the use of an organic amine (e.g. ethylenediamine), which is generally difficult to handle, as a coating solvent for forming the charge generation layer. There are drawbacks. Purpose In view of the above points, the present inventor has conducted extensive studies with the aim of developing a photoreceptor that can be easily manufactured and is suitable for repeated use, and has found that a certain disazo compound can achieve the above purpose. I found out that
This completes the present invention. Structure The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive support, in which the photosensitive layer has the following general formula (). [In the formula, Y is

【formula】

[expression] or

[Formula], R ₁ and R ₂ represent hydrogen, a lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aromatic group, a substituted or unsubstituted heterocyclic group, and R ₁
and R ₂ may be the same or different.
Further, R ₁ and R ₂ may jointly form a ring. ] It is characterized by containing a disazo compound represented by these. Among these photoreceptors, a laminated type photoreceptor is preferred, in which the photoreceptor layer is constructed by laminating a charge generation layer and a charge transport layer, and the charge generation layer contains a disazo compound of the general formula (2). Here, examples of lower alkyl groups in general formula () include methyl group, ethyl group, propyl group, etc., examples of aralkyl groups include benzyl group, phenethyl group, etc., and examples of aromatic groups include phenyl group, naphthyl group, anthryl group. , pyrenyl group, anthraquinonyl group, etc.; examples of heterocyclic groups include thienyl group, furyl group, pyridyl group, and carbazolyl group; examples of the ring formed by R ₁ and R ₂ include hexylidene ring, pentylidene ring, Examples include a benzopentylidene ring and a dibenzopentylidene ring. Substituents on the aralkyl group, aromatic group, heterocyclic group, or the ring formed by R ₁ and R ₂ include a lower alkyl group, a lower alkoxy group,
Examples include a halogen atom, a cyano group, a nitro group, and a lower dialkylamino group. The present invention will be explained in more detail below. First, specific examples of the disazo compound used in the present invention are as follows.

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[Table] The above disazo compounds include 2,2'-diaminostilbene, 2,3'-diaminostilbene, 2,
4'-Diaminostilbene, 3,4'-diaminostilbene or 4,4'-diaminostilbene was converted into diazonium by the diazotization method described in JP-A-52-8832 or JP-A-54-20737. It can be easily obtained by coupling the salt with the corresponding 2-hydroxy-3-naphthoic acid hydrazide in an appropriate organic solvent such as N,N-dimethylformamide (DMF) by reacting with a base. can be manufactured. Although the charge transporting substance used in the present invention is not specified, typical examples thereof are as follows. [R ¹⁰ is an alkyl group such as a methyl group or an ethyl group, a substituted alkyl group such as a 2-chloroethyl group or a 2-hydroxyethyl group, R ¹¹ is an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, or a phenyl group. aryl group such as hydrogen atom, halogen atom such as chlorine, ^bromine , alkyl group such as methyl group, ethyl group, propyl group, butyl group, alkoxy group such as methoxy group, ethoxy group, propoxy group, butoxy group group, dialkylamino group or nitro group. ] [Ar′ represents a naphthyl group, anthryl group, styryl group, or a substituent thereof; R ¹³ represents an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, or an aryl group such as a phenyl group.
Examples of substituents on naphthyl, anthryl, and styryl groups include alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, and dialkylamino groups such as dimethylamino and diethylamino groups. It will be done. ] [R ¹⁴ , R ¹⁵ or R ¹⁷ is a hydrogen atom, a methyl group,
It represents an alkyl group such as an ethyl group or a propyl group, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, a halogen atom such as chlorine or bromine, a nitro group or a hydroxyl group, and R ¹⁶ is a hydrogen atom, a methyl group, an ethyl group, Alkyl groups such as propyl groups, alkoxy groups such as methoxy, ethoxy, and propoxy groups, dialkylamino groups such as dimethylamino and diethylamino groups, dialkylamino groups such as dibenzylamino groups, and diarylamino groups such as diphenylamino groups. , a halogen atom such as chlorine or bromine, a nitro group or a hydroxyl group, R ¹⁸ represents an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, or an aryl group such as a phenyl group. ] [R ¹⁹ , R ²⁰ , R ²¹ or R ²² is a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group,
It represents an alkoxy group such as a methoxy group, an ethoxy group, or a pyrropoxy group, a dialkylamino group such as a dimethylamino group or a diethylamino group, a halogen atom such as chlorine or bromine, a nitro group, or a hydroxyl group. ] [ ^R23 is an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted heterocyclic group, ^R24 or ^R25 is a hydrogen atom, methyl group, ethyl group, propyl group, butyl group represents an alkyl group, a chloro-substituted alkyl group, a hydroxy-substituted alkyl group, a substituted or unsubstituted aralkyl group, and R ²⁴ and R ²⁵ may be bonded to each other to form a nitrogen-containing heterocycle. R ²⁶ or R ²⁷ is a hydrogen atom,
It represents an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkoxy group such as a methoxy group or an ethoxy group, or a halogen atom such as chlorine or bromine. Examples of the heterocyclic group for R ²³ include pyridyl group, furyl group, thienyl group, indolyl group, pyrrolyl group,
Examples include quinolyl group and carbazolyl group.
Examples of the substituent on the phenyl group or heterocyclic group of R ²³ include alkyl groups such as methyl group and ethyl group, and alkoxy groups such as methoxy group and ethoxy group. Examples of the aralkyl group for R ²⁴ or R ²⁵ include a benzyl group, and examples of substituents in the aralkyl group include chlorine,
Examples include halogen atoms such as bromine, alkyl groups such as methyl and ethyl groups, and nitro groups. ^R24
An example of the heterocycle formed by bonding R 25 and R ²⁵ to each other is a morpholine ring. ] [ ^R28 is a hydrogen atom, a halogen atom such as chlorine or bromine, ^R29 is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group or an ethyl group,
Alkoxy groups such as methoxy and ethoxy groups, dialkylamino groups such as dimethylamino, diethylamino and dibutylamino groups, dialkylamino groups such as dibenzylamino and chloro-substituted dibenzylamino groups, nitro groups, cyano groups,

[Formula] R ³⁰ represents a hydrogen atom, a halogen atom such as chlorine or bromine, or an alkyl group such as a methyl group or an ethyl group. ] [R ³¹ is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group, an ethyl group or a butyl group, an alkoxy group such as a methoxy group, an ethoxy group or a butoxy group, or a cyano group, R ³² or
R ³³ is a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a butyl group, a substituted alkyl group such as a 2-chloroethyl group or a 2-hydroxyethyl group, or a substituted or unsubstituted benzyl group, R ³⁴ or
R ³⁵ is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group, an ethyl group or a butyl group, an alkoxy group such as a methoxy group, an ethoxy group or a butoxy group, or a dialkylamino group such as a dimethylamino group or a diethylamino group. represents a group. ^R32
Examples of the substituent on the benzyl group of R ³³ include alkyl groups such as methyl group and ethyl group, alkoxy groups such as methoxy group and ethoxy group, and nitro group. ] [Ar″ represents an N-alkylcarbazolyl group, and examples of the alkyl group include a methyl group, ethyl group, propyl group, and butyl group.] [R ³⁶ , R ³⁷ and R ³⁸ are hydrogen atoms, halogen atoms such as chlorine and bromine, alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, nitro groups or amino groups, R ³⁸ is Hydrogen atoms, halogen atoms such as chlorine and bromine, methyl groups,
Alkyl groups such as ethyl groups, alkoxy groups such as methoxy groups and ethoxy groups, dialkylamino groups such as dimethylamino groups, diethylamino groups, and dibutylamino groups, dibenzylamino groups, chloro-substituted dibenzylamino groups, and methyl-substituted dibenzylamino groups. group, a substituted or unsubstituted dialkylamino group such as a methoxy-substituted dibenzylamino group, an N-alkyl-N-aralkyl amino group such as an N-methyl group-N-benzylamino group, a carboxy group or its ester, an amino group , represents a hydroxy group, a cyano group, or an acetylamino group. ] [ ^R40 is an N-alkyl group, carbazolyl group, pyridyl group, thienyl group, indolyl group, furyl group,
Alternatively, each represents a substituted or unsubstituted naphthyl group, styryl group or anthryl group. Examples of substituents on naphthyl, styryl, and anthryl groups include alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, and dialkylamino groups such as dimethylamino and diethylamino groups. [R ⁴¹ and R ⁴² are hydrogen atoms, methyl groups, ethyl groups,
It represents an alkyl group such as a butyl group, an alkoxy group such as a methoxy group, an ethoxy group, a butoxy group, a halogen atom such as chlorine or bromine, or a dialkylamino group such as a dimethylamino group or a diethylamino group, and n ₁ represents 0 or 1. . ] [R ⁴³ and R ⁴⁴ are hydrogen atoms, alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, halogen atoms such as chlorine,
R ⁴⁵ and R ⁴⁶ are methyl group, ethyl group, propyl group,
An alkyl group such as a butyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, and R ⁴⁷ represents a hydrogen atom or a substituted or unsubstituted phenyl group. Examples of the aralkyl group for R ⁴⁵ and R ⁴⁶ include a benzyl group, and examples of the aryl group include a phenyl group. Substituents on aralkyl or aryl groups include alkyl groups such as methyl, ethyl, and butyl, alkoxy groups such as methoxy and ethoxy, halogen atoms such as chlorine, and dialkyl groups such as dimethylamino and diethylamino groups. An example is an amino group. ] [R ⁴⁸ and R ⁴⁹ represent an alkyl group such as a methyl group or an ethyl group, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group. Examples of the substituent include alkyl groups such as methyl group and ethyl group, and alkoxy groups such as methoxy group and ethoxy group. ] [R ⁵⁰ and R ⁵¹ represent the same groups as R ⁴⁸ and R ⁴⁹ above. ] [ ^R52 is a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, a substituted or unsubstituted phenyl group,
n ₂ is an integer of 0 or 1, A is

【formula】

[Formula] represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group. Here, R ⁵³ is a hydrogen atom, an alkyl group,
Alkoxy group, halogen atom or

[Formula] Substituted amino group (R ⁵⁴ and R ⁵⁵ are methyl groups,
It represents an alkyl group such as an ethyl group, a propyl group, a butyl group, a substituted or unsubstituted aralkyl group such as a benzyl group, a substituted or unsubstituted aryl group such as a phenyl group, and R ⁵⁴ and R ⁵⁵ form a ring. You may. ), m represents an integer of 0, 1, 2, or 3, and when m is 2 or more, R ⁵⁴
may be the same group or different groups. ^R54 or
Substituents on the aralkyl group or aryl group in ^R55 include alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkoxy groups such as methoxy and ethoxy groups, halogen atoms such as chlorine, dimethylamino groups, Examples include dialkylamino groups such as diethylamino groups. ] Further, specific examples of these charge transport substances are as follows.

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[Table] In addition to the above-mentioned exemplified compounds, polymer substances include poly-N-vinylcarbazole, halogenated-poly-N
- vinyl carbazole, polyvinylpyrene, or bromopyrene-formaldehyde condensation resin,
Condensation resins such as N-ethylcarbazole-formaldehyde condensation resin, and low molecular weight substances such as oxazole derivatives, oxadiazole derivatives, and nitro derivatives of fluorenone are all effective. FIG. 1 is an enlarged sectional view of an electrophotographic photoreceptor showing an embodiment of the present invention. This photoreceptor is constructed such that a charge generation layer 22 and a charge transport layer 33 are provided on a conductive support 11 to form a photosensitive layer 44 . The conductive support used in the present invention includes a metal plate, metal drum, or metal foil made of aluminum, nickel, chromium, etc.;
Plastic films provided with a thin layer of tin oxide, indium oxide, chromium, palladium, etc., and paper or plastic films coated with or impregnated with a conductive substance are used. The charge generation layer 22 is made of a liquid in which a specific disazo compound represented by the general formula () shown above is made into fine particles by means such as a ball mill, and dispersed in a suitable solvent, or if necessary, a binder resin is added thereto. A dissolved dispersion liquid is coated on the conductive support 11, and if necessary, the surface is finished by buffing or the like, and the film thickness is adjusted. The thickness of the charge generation layer 22 is 0.01 to 5 μm, preferably 0.05 to 2 μm, and the proportion of the disazo compound in the charge generation layer 22 is 10 to 100% by weight, preferably 30 to 95% by weight. The thickness of the charge generation layer 22 is
Below 0.01 μm, sensitivity is poor, and above 5 μm, potential retention is poor. Furthermore, if the proportion of the disazo pigment in the charge generation layer is less than 10% by weight, the sensitivity will be low. The charge transport layer 33 is formed by coating the charge generation layer with a solution in which the various charge transport substances described above and a binder resin are dissolved in a suitable solvent such as tetrahydrofuran. Here, the ratio of the charge transport substance contained in the charge transport layer 33 is 10 to
The amount is 80% by weight, preferably 25 to 75% by weight, and the film thickness is 2 to 100 μm, preferably 5 to 40 μm.
If the proportion of the charge transport substance contained in the charge transport layer 33 is less than 10% by weight, the sensitivity will be poor, and if it is more than 80% by weight, the film will become brittle or crystals will precipitate.
3 becomes cloudy, which is not preferable. In addition, the charge transport layer 3
If the thickness of 3 is less than 2μm, the potential is not maintained well.
At 100 μm or more, the residual potential becomes high. Examples of the binder resin for the charge generation layer 22 used here include polyester resin, butyral resin, ethyl cellulose resin, epoxy resin, acrylic resin, vinylidene chloride resin, polystyrene,
Examples include polybutadiene and copolymers containing at least one of these monomers, which may be used alone or in a mixture of two or more. Further, as the binder resin for the charge transport layer 33, polycarbonate resin, polyester resin,
Examples include polystyrene, polyurethane resin, epoxy resin, acrylic resin, silicone resin, and copolymers containing at least one of these monomers, which may be used alone or in a mixture of two or more. Furthermore, various additives can be added to the charge transport layer 33 for the purpose of improving flexibility or durability. Examples of additives used for this purpose include halogenated paraffin, dialkyl phthalate, silicone oil, etc. In the photoreceptor of the present invention, if necessary, the conductive support 11 is placed between the charge generation layer 22 and the like. barrier layer,
An intermediate layer may be provided between the charge generation layer 22 and the charge transport layer 33, and an overcoat layer may be provided on the charge transport layer 33. Further, the disazo compound of the general formula () according to the present invention can be used as a dispersed photoreceptor by dispersing it as fine particles in a binder resin (a charge transporting substance may be added if necessary). You can also do that. Effects The structure of the present invention is as described above, and as is clear from the examples described later, the electrophotographic photoreceptor of the present invention is easy to manufacture and has stable characteristics even when the photoreceptor is repeatedly used. It has excellent properties. EXAMPLES Next, the present invention will be specifically explained using Examples, but the embodiments of the present invention are not limited thereby. Example 1 76 parts by weight of disazo compound No. 1-32, 1260 parts by weight of a tetrahydrofuran solution (solid content concentration 2%) of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.), and 3700 parts by weight of tetrahydrofuran were placed in a ball mill. The resulting dispersion was applied using a doctor blade onto the aluminum surface of an aluminum-deposited polyester base (conductive support) and air-dried to form a charge generation layer with a thickness of approximately 1 μm. did. On the other hand, 2 parts by weight of charge transport substance 2-29, polycarbonate resin (Panlite K1300,
Teijin Ltd.) 2 parts by weight and tetrahydrofuran 16
After mixing and dissolving parts by weight to form a solution, this was applied onto the charge generation layer using a doctor blade and heated at 80°C.
Dry for 2 minutes at 100℃ and then 5 minutes at 100℃ to a thickness of approx.
A charge transport layer of 20 μm was formed, and a laminated photoreceptor No. 1 as shown in FIG. 1 was prepared. Examples 2 to 50 Example 1 except that the disazo compound and charge transport substance shown in Table 1 below were used instead of disazo compound No. 1-32 and charge transport substance 2-29 used in Example 1. Photoreceptors Nos. 2 to 50 were prepared in the same manner as described above. These photoconductors No. 1 to 50 were negatively charged by performing -6KV corona discharge for 20 seconds using an electrostatic copying paper testing device (manufactured by Kawaguchi Electric Seisakusho Co., Ltd., model SP428). , leave it in a dark place for 20 seconds, measure the surface potential Vpo (V) at that time, then irradiate the surface with light using a tungsten lamp at an illuminance of 4.5 lux until the surface potential is 1/1 of Vpo. Find the time (seconds) until it becomes 2, and calculate the exposure amount E1/2
(lux/second) was calculated. Table 1 shows the results.
Shown below.

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[Table] Furthermore, photoreceptors of the present invention No. 1, No. 11, No. 21, No.
31 and No. 41 on the Ricoh Co., Ltd. copier Ricopy P-
500 and repeated image generation 10,000 times. As a result, clear images were obtained from all photoreceptors. From this, it can be understood that the photoreceptor of the present invention has extremely excellent durability.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention. 11... Conductive support, 22... Charge generation layer,
33... Charge transport layer, 44... Photosensitive layer.

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, the photosensitive layer contains the following general formula (). [Wherein, Y represents [Formula] [Formula] or [Formula], R ₁ and R ₂ are hydrogen, lower alkyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aromatic group, substituted or Represents an unsubstituted heterocyclic group, R ₁
and R ₂ may be the same or different. Further, R ₁ and R ₂ may jointly form a ring. ] An electrophotographic photoreceptor characterized by containing a disazo compound represented by the following.