JPS63151958A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body superior in durability and resistance to environmental conditions capable of maintaining characteristics stable by incorporating at least one of specified azo compounds as a carrier generating material in a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body has on an electric conductive substrate the photosensitive layer at least one of the azo compounds represented by formula I in which each of R1-R3 is H, halogen, alkyl, or alkoxy; A is a coupler residue having a phenolic hydroxyl group; and each of m and n is 0 or 1 but, at least one of them is not 0. Since the azo compound and the carrier transfer material themselves have no film forming capability, a binder resin is used to form the photosensitive layer. A preferably binder resin is a highly insulating film forming polymer or copolymer, thus permitting the obtained electrophotographic sensitive body to be superior in electric charge retentivity from low to high temperature and from low to high humidity, resistance to environmental conditions, such as temperature change, and durability.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor, and more specifically, a specific Ab compound is coated as a carrier generating substance on a conductive support. By making it contain.

The present invention provides a novel electrophotographic photoreceptor having excellent photosensitivity and durability.

(Prior Art) The electrophotographic method has already been published by Carlson in US Patent No. 2.297.
As disclosed in No. 691, this photographic method cleverly combines electrostatic phenomena and photoconductive phenomena, and uses a photoconductive photoreceptor in a dark place by corona discharge or the like.

An image forming method that uses photoconductivity to uniformly charge the surface and then convert the optical image into an electrostatic latent image, which is then converted into a visible image by attaching colored charged powder (toner) to it. There is one.

The basic electrical and photoelectric properties required of a photoreceptor in such electrophotography are that it can be charged to an appropriate potential in a dark place, that this potential can be maintained for an appropriate amount of time, and that it can be charged quickly by light irradiation. For example, the electric charge can be dissipated.

In such photoreceptors, amorphous selenium,
Inorganic photoconductive materials such as cadmium sulfide and zinc oxide are widely used in lids. Although these inorganic materials satisfy the above conditions, they also have some drawbacks. For example, cadmium sulfide or zinc oxide is used as a photoreceptor by dispersing it in a resin as a binder.

Since it has mechanical defects such as smoothness, flexibility, hardness, tensile strength, and abrasion resistance, it cannot withstand repeated use as it is. Furthermore, when using cadmium sulfide, consideration must also be given to hygiene issues.

In addition, amorphous selenium must be manufactured by vapor deposition, which not only increases manufacturing costs but also has no flexibility and is difficult to process into a belt shape.
It has drawbacks such as the toxicity of selenium and its sensitivity to heat and mechanical shock, so care must be taken when handling it.

In recent years, in order to eliminate the drawbacks of these inorganic photoreceptors,
Research on organic photoreceptors is progressing, and organic photoreceptors.

Easy to form a film, easy to manufacture, lightweight.

Various organic photoreceptors have been proposed and some are in practical use because they have many advantages such as flexibility and multimodality of two-spectral sensitivity.

For example, poly-N-vinylcarbazole and 2.4°7-
Photoreceptor consisting of dolinitrofluorene-9-one (US Pat. No. 3,484,237), poly-N-vinylcarbazole sensitized with biryllium base dye (Japanese Patent Publication No. 1983-25658), dye Photoreceptor whose main component is a eutectic complex consisting of
Publication No.) etc.

Furthermore, electrophotographic photoreceptors have been proposed that combine a substance that generates carriers when exposed to light (called a carrier-generating substance) and a substance that can transport the generated carriers (called a carrier-transporting substance). . For example, U.S. Pat. No. 3.791.826 discloses a photoreceptor in which a carrier transport layer is provided on a carrier generation layer, and U.S. Pat. Photoreceptors have been described that have a photosensitive layer dispersed in a transport material. By assigning the functions of this type of carrier generation and carrier transport to separate substances, that is, by combining the carrier generation substance and the carrier transport substance, the characteristics can be improved and a useful photoreceptor can be provided. be done.

Until now, in this type of photoreceptor, carrier generation@! A number of proposals have been made to use azo compounds as J substances.

For example, as a photoreceptor containing an azo compound in the photosensitive layer, JP-A-57-102629. Japanese Patent Publication No. 57-1321
59. Japanese Patent Publication No. 57-191644. JP-A-5'l-17
6055, JP-A-58-147746, etc. are already known. However, these azo compounds
It is not always completely satisfactory in terms of characteristics such as sensitivity, residual potential, or stability during repeated use.
Furthermore, the selection range of carrier transporting substances is also limited, and the reality is that nothing has yet been found that completely satisfies the wide range of requirements of electrophotographic processes.

(Problems to be Solved by the Invention) The present invention provides an electrophotographic photoreceptor containing a specific azo compound that is excellent in sensitivity, repeatability, durability, and the like.

[Structure of the invention]

(Means for Solving the Problem) As a result of intensive research, the present inventors have discovered that an azo compound having a specific structure is a truly useful carrier-generating substance for electrophotographic photoreceptors. The present invention was completed based on the discovery that an electrophotographic photoreceptor using this carrier-generating substance has excellent properties.

Specifically, the present invention provides an electrophotographic photoreceptor having excellent properties using an azo compound having a novel structure.

An object of the present invention is to provide an electrophotographic photoreceptor that has high sensitivity and low residual potential by containing a novel carrier-generating substance, and further has high carrier generation efficiency and thus has a high copying speed. Another object of the present invention is that when used as a photoreceptor for repetitive transfer type electrophotography in which charging exposure, development, and transfer steps are repeated, fatigue deterioration due to repeated use is small, and furthermore, the present invention is more effective than low temperatures, high temperatures, and low humidity. An object of the present invention is to provide an electrophotographic photoreceptor with excellent durability and environmental resistance that maintains stable characteristics under various harsh environments such as high humidity. Further, among these electrophotographic photoreceptors, those having spectral sensitivity at 780 nm or more can also be provided as photoreceptors for printers using Ar laser, He-Ne laser, or semiconductor laser as a light source.

This object of the present invention is achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing at least one azo compound represented by the following general formula [I] as a carrier generating substance.

General formula ([) (wherein R+, Rz and R3 represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxyl group.

A represents a coupler residue containing a phenolic hydroxyl group. m and n represent 0 or l, but at least one of m and n shall not be 0. ) The above general formula (
Preferred specific examples of the cuff puller residue having a phenolic hydroxyl group in A in 1) are represented by general formulas (II) to Vl).

General formula (II) General formula (I or an aryl group; Z represents a substituted or unsubstituted divalent group of an aromatic hydrocarbon or a divalent group of an aromatic heterocycle containing a nitrogen atom in the ring.) Next, the general formulas (1) to [VD The substituents will be specifically explained.

R4, R5 and R6 are each hydrogen atom; methyl group,
Unsubstituted alkyl groups such as ethyl, propyl, and butyl; substituted alkyl groups such as chloromethyl, hydroxyethyl, and diethylaminoethyl; unsubstituted aralkyl groups such as benzyl, phenethyl, cinnamyl, and naphthylmethyl ; substituted aralkyl groups such as methylbenzyl group, methoxybenzyl group, and chloronaphthyl group; unsubstituted aryl groups such as phenyl group, naphthyl group, anthryl group, and pyrenyl group; tolyl group, methoxyphenyl group, and xylyl group.

Methylnitrophenyl group, chlorophenyl group, dichlorophenyl group, nitrophenyl group, dinitrophenyl group,
Substituted aryl groups such as chloronitrophenyl group, trifluoromethylphenyl group, cyanophenyl group, chloronaphthyl group, nitronaphthyl group; pyridyl group, phthalazinyl group, benzothiazolyl group.

Unsubstituted aromatic heterocyclic groups such as carbazolyl group; substituted aromatic heterocyclic groups such as methylbenzothiazolyl group and chlorocarbazolyl group.

R,, Rz and R5 are hydrogen atoms; halogen atoms such as chlorine atom and bromine atom; methyl group and ethyl group.

Alkyl groups such as propyl groups; alkoxy groups such as methoxy, ethoxy, and propoxy groups.

Further, Z is a divalent group of an unsubstituted aromatic hydrocarbon such as a phenylene group or a naphthylene group; a tolylene group, a xylylene group, a chlorphenylene group, or a nitrophenylene group.

Divalent groups of substituted aromatic hydrocarbons such as methoxyphenylene group and methylnaphthylene group: pyridinediyl group.

Unsubstituted aromatic heterocyclic divalent groups such as triazolediyl group and imidazolediyl group; methylpyridinediyl group,
It is a divalent group of a substituted aromatic heterocycle such as a chloroquinolinediyl group.

Next, typical examples of the azo compound of the present invention are listed below.

(The following is a blank space) The azo compound represented by the general formula CI) is represented by the general formula [■
] (R+, R1, R, m and n are the same as in (1)) by a conventional method.

It can be easily obtained by diazotization or tetrazotization and then campling with various couplers in water, dimethylformamide, dimethylsulfoxide, or other organic solvent in the presence of an alkali. Alternatively, a diazonium salt or a tetrazonium salt of a monoamine or diamine may be isolated in the form of a borofluoride salt, zinc chloride double salt, etc., and then coupled. During this diazotization and coupling reaction.

Even if a compound in which some amino groups remain unreacted is present, the electrophotographic properties will not be adversely affected.

Next, regarding representative examples of azo compounds used in the present invention,
The synthesis method is shown below.

Synthesis example (synthesis of exemplified compound (2)) 23.4 g (0.1 mol) of diamine shown by the above structure
with concentrated hydrochloric acid 1. OR, dispersed in 0.5 ml of water, cooled to below 5°C, and added 13.8 g (0.2 mol) of sodium nitrite little by little. After the addition is complete, the mixture is stirred at 5° C. or lower for 1 hour, then 5 g of activated carbon is added, stirred for 10 minutes, and then filtered to obtain a tetrazonium salt.

Next, 52.6 g (0.2 mol) of 2-hydroxy-3 phenylcarbamoyl-naphthalene was added to 52.6 g (0.2 mol) of water.
, 2 mol) in water 5. Oj! is dissolved in an alkaline aqueous solution containing 16 g of sodium hydroxide, and the above tetrazonium solution is added dropwise to the solution while stirring at 10° C. or lower. PH during dropping is 8.0
Adjust by adding sodium carbonate aqueous solution dropwise so that it does not become below. After dropping the tetrazonium solution.

After stirring at 20-30°C for 2 hours, the precipitated crystals were filtered, washed with 1% aqueous sodium hydroxide solution, washed with water and acetone, and dried to obtain a compound (2150 g).

These compounds may be used alone or in combination of two or more.

The photoreceptor of the present invention contains a specific azo compound as a carrier generating substance as described above, and also contains various carrier transport substances, but it has various characteristics depending on how these specific ab compounds are applied. A photoreceptor of 100% is obtained.

For example, a structure usually referred to as a single-layer photoreceptor in which a carrier transport material is provided on a conductive support substrate in the same layer as a carrier-generating material, or a first layer mainly containing a carrier-generating material.

It can be used in a configuration commonly referred to as a laminated type photoreceptor, which is made by laminating two second layers mainly containing a carrier transporting substance on a conductive support substrate. These configurations are appropriately selected depending on the polarity of the photoreceptor used.

Carrier transport substances used in the present invention include, for example, hydrazones, pyrazolines, diarylalkanes, alkylene diamines, and triphenylamines.

Benzylanilines, diphenylbenzylamines.

Various compounds include, but are not limited to, triarylalkanes, oxadiazoles, oxazoles, stilbenes, and anthracenes. A more specific example is as follows.

2H5 Since the azo compound and carrier transport substance in the present invention do not have film-forming ability by themselves, a binder resin is used to form them as a photosensitive layer.

The binder preferably used in the present invention is a highly electrically insulating film-forming polymer or copolymer. These high molecular weight polymers and copolymers are 1
Binders preferably used in the present invention include phenolic resin, polyester resin, vinyl acetate resin, polycarbonate resin, polypeptide resin, cellulose resin, polyurethane resin, polyvinylpyrrolidone, polyethylene oxide, polyvinyl chloride resin, starch, and polyvinyl alcohol. .

Acrylic copolymer resin, vinyl chloride vinyl acetate copolymer resin, methacrylic copolymer resin, silicone resin, polyacrylonitrile copolymer resin, polyacrylamide,
Examples include polyvinyl butyral, polyvinyl carbazole, polyvinylidene chloride resin, and silicone resin.

These polymeric binders can be used alone or in combination of two or more, but the binders that can be used in the present invention include:
It is not limited to these. Further, in the photoreceptor of the present invention, a carrier generation layer containing a carrier generation substance as a main component is provided on the conductive support via an intermediate layer if necessary, and adjacent to the carrier generation layer the main component is a carrier transporting substance. A laminated structure including a carrier transport layer may also be used, and such a laminated structure may be used.

Which of the carrier generation layer and the carrier transport layer is to be used as the upper layer is determined depending on whether the chargeability is positive or negative. Generally, when negatively charged, it is advantageous in terms of characteristics to have a carrier transport layer as an upper layer. Further, in the photoreceptor of the present invention, there is a case where the photoreceptor has a laminated structure consisting of a carrier generation layer and a carrier transport layer, each of which is a separate layer.

The photosensitive layer is formed directly on the conductive support, or after providing an intermediate layer such as an adhesive layer or a barrier layer as necessary, a carrier-generating substance is micronized in a dispersion solvent using a ball mill, an attritor, etc., as necessary. After coating the dispersion obtained by mixing and dispersing with a polymeric binder, the carrier transport substance and the polymeric binder are further mixed with dioxane, dichloromethane, or dichloroethane.

It can be produced by coating a solution dissolved in an organic solvent such as tetrahydrofuran.

In the case of a single-layer type photoreceptor, a carrier-generating substance, a carrier-transporting substance, and a polymer binder are added to the same organic solvent, and a coating liquid is dispersed using a ball mill, an attritor, etc., and then applied to the conductive support. It can be created by

In addition, 5 carrier transport substances used in the present invention are 9 binders 10
10 to 300 parts by weight of carrier transport material per 0 part by weight is preferred. However, the present invention is not limited to this range only, and the thickness of the photosensitive layer depends on the required photosensitivity and durability and the mixing ratio of the carrier generating substance and the carrier transporting substance to the binder. In either case, the thickness of the photosensitive layer on the supporting conductive substrate is determined to be 50 microns or less, preferably about 7 to 30 microns, from the viewpoint of film flexibility. Appropriate.

The photosensitive layer can also be coated with a layer that serves as a protective layer, if necessary.

The support used in the electrophotographic window illuminator of the present invention may be any support as long as it is imparted with electrical conductivity, and any type of conductive N or N conventionally used may be used. Specifically, aluminum and copper.

Metal such as stainless steel, brass, aluminum, indium oxide, tin oxide, etc. 1 layer or laminated plastic or conductive particles 1 For example, carbon blank,
Examples include plastics in which tin particles or aluminum particles are dispersed. Further, the shape thereof may be a sheet shape, a cylinder shape, or other shapes.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples. Hereinafter, in the examples, the compound used in the example refers to the compound added in the above example, and "part" refers to part by weight.

Example 1 Compound (1) 0.
4 parts polyester resin (Vylon 200) 0
．． 5 parts 1,2-dichloroethane 9
．． 5 parts or more of the composition was dispersed in a vibrating mill for 2 hours, and the resulting photoconductive composition was coated on an 80μ aluminum plate with a wire bar to a dry film thickness of 0.5μ. A charge generation layer is formed by drying for 1 hour in an oven uniformly heated to 100°C. Next, a solution having the following composition was prepared so that the solution had a thickness of 15μ on the carrier generation layer.

compound (a')
Q, 3-part polyester resin (Byron 200 >
0.4 part dichloroethane
A 2.6 part composition was coated with a wire bar and dried for 30 minutes in an oven uniformly heated to 80° C. to produce a laminated photoreceptor.

-5, OKV for the sample thus obtained.

Corona discharge was applied at a charging speed of 10 m/min using a corona force of +7 and a charging speed of 10 m/min. After 10 seconds, a tungsten light source of 2854 was used to apply corona discharge. Expose with OLux illuminance. The amount of light irradiation required for the potential immediately before exposure to decrease by 50% at this time was defined as the sensitivity. The sample measured in this way had a maximum surface charge of -520V.

The dark decay rate was 4.3%, the sensitivity was 2.9 Lux, sec, and the residual potential was -22 V.

Example 2 Compound (2) 0.4
Part acrylic resin (Dianal HR113) 0.
2 parts vinyl chloride-vinyl acetate resin (VMCH) 0
．． 2 parts ethyl acetate 14
The photoconductive composition was dispersed in a vibrating mill for 2 hours, and the resulting photoconductive composition was coated with an aluminum foil having a thickness of 5 μm.
A carrier-generating layer is formed by coating the laminate film with a polyester film of 0.5 μm using a wire bar so that the dry film thickness becomes 0.5 μm, and leaving it in an oven uniformly heated to 130° C. for 1 hour.

Then, in Example 1, compound (b) was substituted for compound (a).
When a laminated photoreceptor was prepared and tested in the same manner as in Example 1, the maximum surface charge amount was -560■, and the dark decay rate was 6
．． 3%, sensitivity 2.4 Lux-sec, residual potential -1
It was 5V.

Example 3 Compound (3) 1 part Compound (d) 2.
5 parts acrylic polyol (Takelac A-702)3.
6 parts epoxy resin (Epon 1007) 0
．． 5 parts methyl ethyl ketone 1
．． 2 parts cellosolve acetate 1
．． Two or more parts of the composition are milled in a magnetic ball mill for 48 hours to obtain a photoconductive composition.

Next, this composition was placed on an 80μ aluminum plate to a dry film thickness of 8μ.
The photoreceptor was coated with a wire bar so that the photoreceptor was coated with a wire bar, and placed in an oven uniformly heated to 110° C. for 1 hour to obtain a single-layer photoreceptor. In this way, for the obtained sample, Example 1
The maximum surface charge amount was 490 V when measured as corona discharge +5.7 KV.

Dark decay rate 9.3%, sensitivity 3. I Lux-sec
, residual potential=19V.

Example 4 In the same manner as in Example 1, using compound (6) instead of compound (1) and using polycarbonate resin (Panlite L-1250) instead of polyester resin (Vylon 200). , a laminated photoreceptor was created. When the sample thus obtained was measured in the same manner as in Example 1, the maximum surface charge amount was -51 OV, the dark decay rate was 8.3%, the sensitivity was 3.6 Lux-sec, and the residual potential was -27 V.

Examples 5 to 16 The carrier-generating material and carrier-transporting material of Example 4 were replaced with the materials shown in the table below, and tests were conducted in the same manner.

〔Effect of the invention〕

The present invention has the above configuration, and when using it,
High sensitivity even in positive and negative charging, and
There is little deterioration of the photoconductor due to repeated use.

In addition, in practical use, it has excellent characteristics such as charge retention ability from low temperature to high temperature and from low humidity to high humidity, environmental friendliness with respect to sensitivity changes, and durability.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing at least one azo compound represented by the following general formula [I] on a conductive support. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, and R_3 represent a hydrogen atom, a halogen atom, an alkyl group, or an alkoxyl group,
A represents a coupler residue having a phenolic hydroxyl group. m and n represent 0 or 1, but at least one of m and n is not 0. ) 2. A of the above general formula [I] is the following general formula [II] ~ [
VI] The electrophotographic photoreceptor according to claim 1. General formula [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [IV] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [V] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ General formula [VI] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_4, R_5, and R_6 are hydrogen atoms, substituted or unsubstituted alkyl groups, aralkyl groups, or aryl Group; Z is substituted or unsubstituted aromatic hydrocarbon 2
Represents a valent group or a divalent group of an aromatic heterocycle containing a nitrogen atom in the ring. ) 3. The photosensitive layer contains a carrier transporting substance and a carrier generating substance, and the carrier generating substance has the above general formula [I
] The electrophotographic photoreceptor according to claim 1, which is an azo compound represented by the following. 4. A patent claim in which the photosensitive layer is constituted by a laminate of a carrier-generating layer containing a carrier-generating substance that is an azo compound represented by the general formula [I] and a carrier-transporting layer containing a carrier-transporting substance. The electrophotographic photoreceptor according to item 1.