JPH01257956A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body almost freed of residual potential by combining an electric charge generating layer containing a specified bisazo pigment with a charge transfer layer containing a benzidine derivative. CONSTITUTION:The electrophotographic sensitive body comprises the charge generating layer containing one of the bisazo pigments represented by formula I and the charge transfer layer containing one of the benzidine derivatives represented by formula II. In formulae I and II, A is an aromatic coupler component; one of R1 and R2 is H or the like and the other of them is alkyl or the like; R3 is H, alkyl, or the like; and each of R4 and R5 is H or like when R3 is H or the like, thus permitting the electrophotographic sensitive body to be superior in chargeability, rapid in decay of potential due to exposure to light, high in sensitivity, small in dependence of the potential decay on the electric field, easy to cause photodecay, even when low in potential, small in trailing of potential, and almost freed of residual potential.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor having a layer structure in which a charge generation layer and a charge transport layer are functionally separated.

Conventional technology Conventional electrophotographic photoreceptors include those with a single-layer photoconductive layer and those with a multilayer photoconductive layer.In particular, in recent years, organic photoconductive materials have been bonded with resin etc. as a photoconductive layer, and a charge transport layer has been developed. Various proposals have been made regarding an organic electrophotographic photoreceptor having a layer structure in which a charge generation layer and a charge generation layer are functionally separated, and various charge generation materials and charge transport materials have also been proposed. For example, known charge generating materials include polycyclic quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, quinacridone pigments, phthalocyanine pigments, monoazo pigments, bisazo pigments, trisazo or polyazo pigments, and charge transporting materials. Examples include amine compounds, hydrazone compounds, pyrazoline compounds, oxazole compounds, oxadiazole compounds, stilbene compounds,
Carbazole compounds and the like are known. Various proposals have also been made to use these charge-generating materials and charge-transporting materials in combination. (For example, JP-A-51i-2
No. 2834, 57-2057112-2057117
No. 57-204042-204053, No. 57-
No. 197544-197551, No. 58-122544
~122551 @ Publication, Publication No. 61-67865, Publication No. 61-124949, Publication No. 61-132953, Publication No. 61-129653, Publication No. 61-221751, Publication No. 62-115452 @ Publication, etc.) The invention will solve the problem However, in order to obtain satisfactory electrophotographic properties in a laminated electrophotographic photoreceptor in which the charge generation layer and charge transport layer are functionally separated, there are two issues: 1. It is necessary to satisfy the following conditions: (2) the generated charges are efficiently injected into the charge transport material and transported. That is, 1
Even if condition 1 is satisfied, if condition 2 is not satisfied, satisfactory photoresponsivity cannot be achieved.

In addition, when the electrophotographic photoreceptor is one in which a charge generation layer and a charge transport layer are laminated in this order, and light irradiation is performed from the charge transport layer side, the following conditions must be met in order to obtain high sensitivity:
It is necessary that the charge transport layer be sufficiently transparent to the light that activates the charge generation layer.

In order to create an electrophotographic photoreceptor using a charge-generating material and a charge-transporting material, the above-mentioned conditions must be met, including sensitivity, acceptance potential, potential retention, potential stability, residual potential, and spectroscopy. Electrophotographic properties such as properties, strength, durability,
A material must be selected that satisfies all aspects, including usage characteristics such as stain resistance, and manufacturing stability and quality stability when manufactured by coating. However, it is very difficult to select a combination of materials that satisfies all of these points, and the above conditions have not been met for the previously proposed combinations of charge-generating materials and charge-transporting materials. I haven't been able to find anything that satisfies me.

The present invention was made in view of the above-mentioned circumstances, and by finding a combination of materials that satisfies all of the requirements for an electrophotographic photoreceptor, an excellent electrophotographic photoreceptor can be produced. The purpose is to provide the following.

Means and Effects for Solving the Problems The above-mentioned object of the present invention is to use the following as a charge generation material of a charge generation layer (1) (wherein A represents an aromatic coupler component, R and R2 One of which represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, or a nitro group, and the other represents an alkyl group, an alkoxy group, a halogen atom, a cyano group, or a nitro group) A pigment is used as the charge transport material of the charge transport layer as shown below - 5R5 (in the formula, R3 represents a hydrogen atom, an alkyl group or an alkoxy group, and R and R5 represent a hydrogen atom when R3 represents a hydrogen atom). are hydrogen atoms, alkyl groups, alkoxy groups, and
Represents a halogen atom, an alkoxycarbonyl group, or a substituted amino group, and when R3 represents an alkyl group or an alkoxy group, represents a hydrogen atom, a methyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group, respectively. ) This can be achieved by using a benzidine compound shown in the following.

That is, the electrophotographic photoreceptor of the present invention is one in which a photosensitive layer consisting of a charge generation layer and a charge transport layer is provided on a conductive substrate, and the charge generation layer is formed of a bisazo resin represented by -I>. The charge transport layer contains a pigment, and the charge transport layer is
It is characterized by containing a benzidine compound represented by:

The present invention will be explained in detail below.

In the present invention, the bisazo pigment contained in the charge generation layer is represented by the above-mentioned -Isen (I>), but specifically, A is the following -Isen (1), (2), (3), (4). ) or (5
) can be used as a group.

('I) ■ ΩH 4) (wherein,
each represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group which each may have a substituent, or a group that combines with a nitrogen atom to form a cyclic amino group, R8 and (R9 represents an optionally substituted alkyl group, aralkyl group, or aryl group, and Y represents a divalent hydrocarbon group) Specific examples of these bisazo pigments include the following compounds.

CI OC1C10C1 In the present invention, the particle size of these bisazo pigments is 2#1
It is preferable to keep it below.

Binder resins for dispersing bisazo pigments include well-known ones, such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymers or copolymers, vinyl acetate polymers or copolymers,
Cellulose esters or ethers, polybutadiene, polyurethane, epoxy resins, etc. are used.

On the other hand, as the charge transport material in the charge transport layer, the benzidine-based compound represented by the above-mentioned -Isen (I[>) is used. Specific examples of the compound represented by -Isen (n) include the following. I'm disappointed.

Since these compounds do not have film-forming properties by themselves, they are used in combination with resins that have good film-forming properties. Examples of resins that can be used include polycarbonate, polyacrylate, polyester, polyarylate, polystyrene,
Styrene-acrylonitrile copolymer, polysulfone,
Examples include polymethacrylic ester, styrene-methacrylic ester copolymer, and the like. Among these, polycarbonate is preferred.

To explain in more detail the method for producing the electrophotographic photoreceptor of the present invention, first, the charge generation layer is formed by dispersing a bisazo pigment in a binder resin solution and coating the solution. As the dispersing means, commonly used ones such as a ball mill, roll mill, sand mill, attritor, etc. can be used. The blending ratio of bisazo pigment and binder resin is 40:1
-1:4, preferably 20:1-1:2. If the ratio of bisazo pigment is too high, the stability of the coating solution will decrease, and if it is too low, the sensitivity will decrease, so
It is desirable to keep it within the above range. Further, as the solvent for the binder resin, any solvent can be used as long as it is soluble, but it is desirable to select a solvent that has good pigment dispersibility. Further, a plurality of solvents may be used in combination.

The charge transport layer is formed by dissolving a benzidine-based compound (n) and a film-forming resin in a solvent that dissolves both, and applying the solution.

The mixing ratio of the former and the former is 5:1 to 1:5, preferably 3:1 to 1:3. If the former ratio is too high, the mechanical strength of the charge transport layer will decrease, and if it is too low, the sensitivity will decrease, so it is desirable to keep it within the above range.

In the electrophotographic photoreceptor of the present invention, the layer structure of the photosensitive layer formed on the conductive substrate may include a charge transport layer provided on the charge generation layer, or a charge transport layer provided on the charge transport layer. A generation layer may also be provided. The thickness of the charge generation layer is 0.05 to 51 m57 The thickness of the charge transport layer is 5 to 5
Further, in the electrophotographic photoreceptor of the present invention, it is preferable to provide a charge injection blocking layer between the photosensitive layer and the conductive substrate.

Example Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 1 part by weight of polyvinyl butyral resin (trade name 2Bx, manufactured by Tansui Kagaku Co., Ltd.) was dissolved in 40 parts by weight of cyclohexanone, and exemplified compound 1-io was added as a charge generating material therein.
3 parts by weight were added thereto and then well dispersed using a paint shaker. The resulting dispersion was applied onto an aluminum sheet using an applicator and dried to form a charge generating layer. The film thickness after drying was 0.2#l.

Next, on this charge generation layer, 31 parts by weight of exemplary compound (1) which is a charge transporting material, polycarbonate resin (trade name Nilexane 145, manufactured by GE Corporation, molecular weight: 35.000-4
A homogeneous solution consisting of 1 part by weight) and 15 parts by weight of dichloromethane was applied using an applicator and dried to form a charge transport layer. The film thickness after drying was 20 mm.

The electrophotographic photoreceptor sheet thus prepared was tested using an electrostatic copying paper tester (5P-428, manufactured by Kawaguchi Electric Seisakusho ■).
The characteristics were evaluated as follows.

First, after negatively charging by -6KV corona discharge, 2
Leave it in the dark for a second, and then the surface potential vo (volt)
Then, using a tungsten lamp, light was irradiated so that the illuminance of the surface was 5 lux, the time required for the surface potential to reach 172 of VO was determined, and the exposed LiE1
/2 (lux-sec) was calculated. VO=-1030
V, El/2=1.51UX-sec.

Examples 2 to 12 Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that the charge-generating materials and charge-transporting materials in Example 1 were replaced by those shown in Table 1. It was evaluated as follows. The results are shown in Table 1.

Table 1 Comparative Example 1 In Example 1, the following structural formula (I
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the compound represented by II) was used, and evaluation was performed in the same manner.

Comparative Example 2 In Example 4, the above structural formula (I
An electrophotographic photoreceptor was prepared in the same manner as in Example 4, except that the compound represented by [I] was used, and evaluation was performed in the same manner.

Comparative Example 3 In Example 7, the above structural formula (I
An electrophotographic photoreceptor was prepared in the same manner as in Example 7, except that the compound represented by II> was used, and evaluation was performed in the same manner.

Comparative Example 4 An electrophotographic photoreceptor was prepared in the same manner as in Example 9, except that a compound represented by the following structural formula was used as the charge transport material, and evaluated in the same manner.

The results are shown in Table 2.

Effects of the Invention In the present invention, by combining the charge generation layer containing the above-mentioned bisazo pigment and the charge transport layer containing the above-mentioned benzidine-based compound, it has good charging properties, fast potential decay due to light irradiation, and high sensitivity. It is possible to obtain an electrophotographic photoreceptor which has a high potential attenuation, has little electric field dependence, and exhibits light attenuation even at a relatively low potential, that is, there is no tailing of the potential and almost no residual potential. Further, the electrophotographic photoreceptor of the present invention includes:
It has the characteristics of good potential stability, low temperature and humidity dependence, extremely low optical fatigue, no deterioration in chargeability due to light, and no so-called optical memory effect, making it very easy to use.

The electrophotographic photoreceptor of the present invention is effectively used in electrophotographic copying machines, but can also be applied to various printers, microfilm readers, electrophotographic engraving systems, etc. that apply xerography technology.

Patent applicant Fuji Xerox Co., Ltd. Agent
Patent attorney Tsuyoshi Seibe

Claims (2)

[Claims] (1) In a laminated electrophotographic photoreceptor in which a photosensitive layer consisting of a charge generation layer and a charge transport layer is provided on a conductive substrate, the charge generation layer has the following general formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼(I) (In the formula, A represents an aromatic coupler component, one of R_1 and R_2 represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a cyano group, or a nitro group, and the other represents a , alkyl group, alkoxy group, halogen atom, cyano group, or nitro group), and the charge transport layer has the following general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) (In the formula, R_3 represents a hydrogen atom, an alkyl group, or an alkoxy group, and when R_3 represents a hydrogen atom, R_4 and R_5 each represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted Indicates an amino group, and when R_3 represents an alkyl group or an alkoxy group, a hydrogen atom, a methyl group,
An electrophotographic photoreceptor comprising a benzidine compound represented by the following formula (representing an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group). (2) A in the general formula (I) above is represented by the following general formula (
The electrophotographic photoreceptor according to claim 1, which is a group represented by 1), (2), (3), (4) or (5). ▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, X is fused with a benzene ring to form a polynuclear aromatic ring or a heterocyclic ring. Indicates the atomic groups necessary to form R_6 and R
_7 each represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group that may each have a substituent, or a group that combines with a nitrogen atom to form a cyclic amino group, and R_8 and R_9 each represent an optionally substituted alkyl group, aralkyl group, or aryl group, and Y represents a divalent hydrocarbon group)