JPS63106758A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body high in sensitivity, small in residual potential, and copying speed by incorporating a specified azo compound as a carrier generating material in a photosensitive layer. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains at least one of the azo compounds represented by formula I in which each of R1 and R2 is H, halogen, alkyl, or alkoxy; A is a coupler residue having a phenolic OH; X is O or S; Y is absent or vinylene, or optionally substituted phenylene; each of m and n is 0 or 1, and at least one of them is not 0, thus permitting the obtained photosensitive body to be high in sensitivity, small in deterioration due to repeated uses, and superior in electric charge retentivity, sensitivity and stability against changes of environmental conditions, 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 azo compound is coated on a conductive support as a carrier generating substance. 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 is an ingenious combination of electrostatic and photoconductive phenomena, in which a photoconductive photoreceptor is exposed in the dark 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 have been widely used. 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.

Nine different organic photoreceptors have been proposed and some are in practical use because they have many advantages such as flexibility and polymorphism in spectral sensitivity.

For example, poly-N-vinylcarbazole and 2.4°7-
photoreceptor consisting of dolinitrofluoren-9-one (US Pat. No. 3,484,237), poly-N-vinylcarbazole sensitized with pyrylium salt dye (Japanese Patent Publication No. 4B-25658), Photoreceptor whose main component is a eutectic complex consisting of a dye and a resin
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. A photoreceptor is described having a photosensitive layer having 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.

Up to now, many proposals have been made for using an azo compound as a carrier generating substance in this type of photoreceptor.

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. Japanese Patent Publication No. 57-176
055. Japanese Unexamined Patent Publication No. 58-147746 and the like are already known. However, these azo compounds do not necessarily fully satisfy the characteristics such as sensitivity, residual potential, or stability during repeated use, and the wide range of requirements for electrophotographic processes such as the limited selection range of carrier transport materials The reality is that nothing that completely satisfies these requirements has yet been found.

(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-based material has excellent properties.

That is, 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 CI) (In the formula, R7 and R2 are hydrogen atoms and halogen atoms.

It represents an alkyl group or an alkoxy group, and A represents a coupler residue having a phenolic hydroxyl group. X represents an oxygen atom or a sulfur atom, and Y represents a direct bond, a vinylene group, or a phenylene group which may have a substituent. Also, m
, n represents 0 or 1, and is 1m.

It is assumed that at least one of n is not 0. ) Preferred specific examples of the coupler residue having a phenolic hydroxyl group of A in the above general formula (1) are general formula (n)
or Vl).

General formula (n) General formula (I[) General formula (IV) General formula (V) General formula (Vl) (wherein R3, R, and R5 are hydrogen atoms, substituted or unsubstituted alkyl groups, aralkyl groups, or Orir group;
2 represents a substituted or unsubstituted divalent group of aromatic hydrocarbon or a divalent group of aromatic heterocycle containing a nitrogen atom in the ring.

) Next, the substituents in the general formulas CI) to Vl) will be specifically explained.

R6, R4 and R5 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, chlorobenzyl group; phenyl group, naphthyl group.

Unsubstituted aryl groups such as anthryl group and pyrenyl group; tolyl group, methoxyphenyl group, xylyl group, methylnitrophenyl group, chlorophenyl group, dichlorophenyl group, nitrophenyl group, dinitrophenyl group, chloronitrophenyl group, trifluoromethylphenyl group unsubstituted aromatic heterocyclic groups such as pyridyl, phthalazinyl, benzothiazolyl, carbazolyl; methylbenzothiazolyl, chlorocarbazolyl; Substituted aromatic heterocyclic group such as ru group.゛R1 and R2 are hydrogen atoms; halogen atoms such as chlorine atom and bromine atom; alkyl groups such as methyl group, ethyl group and propyl group; methoxy group and ethoxy group.

It is an alkoxy group such as a propoxy group.

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,
Substituted aromatics such as chloroquinolinediyl group? 3j is an acyclic divalent group.

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

The azo compound represented by the general formula [I] is represented by the general formula (■
] A monoamine or diamine represented by the general formula [■] (R7, R2+ It can be easily obtained by coupling in dimethyl sulfoxide or other organic solvent in the presence of an alkali. Also,
The diazonium salt or tetrazonium salt of a monoamine or diamine may be isolated in the form of a fluoroborate salt, zinc chloride double salt, etc., and then coupled. During this diazotization and coupling reaction, even if some of the amino groups in the compound remain unreacted, 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 Exemplary Compound (11)) Bis(2-(6-aminebenzothiazolyl)) 29.8
g (0.1 mol) of concentrated hydrochloric acid 2! 13.8 g (0.2 mol) of sodium nitrite is added little by little to this. After adding, heat at 5℃ or below.
After stirring for an hour, 5 g of activated carbon is added, stirred for 10 minutes, and filtered. Add 2 ammonium hexafluoride phosphate to the obtained filtrate.
Add 50 g and filter through the resulting crystals to obtain hexafluorophosphate salt of tetrazonium salt. The crystals are dissolved in N,N-dimethylformamide 51 to prepare a tetrazonium liquid.

Next, 60 g (0.2 mol) of 2-hydroxy-3-(2-chlorophenylcarbamoyl)-naphthalene was added to N,N
- After dissolving in dimethylformamide 2β, 60 g of triethanolamine is added and the above tetrazonium solution is added dropwise while stirring at 5° C. or lower. After dripping.

After stirring at 20-30°C for 2 hours, the precipitated crystals were filtered, washed with N,N-dimethylformamide 2e, further washed with acetone and water, and dried to obtain the compound (
1) 53g is obtained.

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 azo compounds are applied. A photoreceptor of 100% is obtained.

For example, a structure generally 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 containing mainly 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.

(2) 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 high: 11
It is an electrically insulating film-forming polymer or copolymer. Among such polymers and copolymers, binders preferably used in the present invention include phenol resins, polyester resins, vinyl acetate resins, polycarbonate resins, polypeptide resins, cellulose resins, polyurethane resins, and polyvinylpyrrolidone. , polyethylene oxide, polyvinyl chloride resin, starch, 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 polymer binders may be used alone or in combination of two or more, but the binders that can be used in the present invention are 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. Also, if such a laminated structure is 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

9 The carrier transport substance used in the present invention is a binder 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 only to this range. The thickness of the photosensitive layer is determined by the required photosensitivity and durability and the mixing ratio of the carrier generating substance and the carrier transporting substance to the binder. The thickness of the photosensitive layer on the supporting conductive substrate is preferably 50 microns or less, preferably about 7 to 30 microns, from the viewpoint of film flexibility.

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

The support used in the electrophotographic photoreceptor of the present invention may be any material as long as it is imparted with electrical conductivity (any type of electrically conductive layer conventionally used may be used. Specifically, , aluminum, copper.

Examples include metals such as stainless steel and brass, plastics on which aluminum, indium oxide, tin oxide, etc. are vapor-deposited or laminated, and conductive particles 9, such as plastics in which carbon black, tin particles, and aluminum particles are dispersed. Also, regarding its shape,
It may be sheet-shaped, cylindrical or other.

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 number of compounds in the examples refers to the number of compounds added in the examples, and "parts" refers to parts by weight.

Example 1 Compound (110, 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) 0.3
Part polyester resin (Vylon 200) 0
．． 4H dichloroethane 2
．． A composition consisting of 6 parts was coated with a wire bar and 8 parts
A laminated photoreceptor was prepared by drying for 30 minutes in an oven uniformly heated to 0°C.

-5, OKV for the sample thus obtained.

Coronagi'v-/pu 10 mm, 10 m/mi
Corona discharge is applied at a charging speed of n, and after the discharge stops, 1
5. At 2854 tungsten light source after 0 seconds. OL
Expose at ux illuminance. The potential just before exposure at this time is 50
The amount of light irradiation required to reduce the sensitivity by % was defined as the sensitivity. The sample measured in this way had a maximum surface charge of ff1680V.
.

The dark decay rate was 3.6%, the sensitivity was 2.7 Lux, sec, and the residual potential was -12 ■.

Example 2 Compound (5') 0.
4 parts acrylic resin (Dianal HR113) 0
．． 2-part vinyl chloride-vinyl acetate + H fat (VMCH)
0.2 parts ethyl acetate
14 parts or more of the composition was dispersed in a vibrating mill for 2 hours, and the resulting photoconductive composition was mixed with an aluminum foil having a thickness of 5 μm.
A laminate film with a 5 μm polyester film was coated with a wire bar to a dry film thickness of 0.5 μm, and left in an oven uniformly heated to 130° C. for 1 hour to form a carrier generation layer.

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 -590V.

Dark decay rate 6.9%, sensitivity 3. OLux-sec, residual potential was -15V.

Example 3 Compound (8) 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
．． Part 2 cellosolve acetate
A photoconductive composition is obtained by milling 1.2 parts or more of the composition in a magnetic ball mill for 48 hours.

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 left for 1 hour in an open oven heated uniformly to 110° C. to obtain a single-layer photoreceptor. In this way, for the obtained sample, Example 1
According to the above, the maximum surface charge amount was 540 V when measured as corona discharge +5.7 KV.

Dark decay rate 8.9%, sensitivity 2.9 Lux-sec,
The residual potential was -19V.

Example 4 The same procedure as in Example 1 was carried out, except that compound (3) was used instead of compound (1) and polycarbonate resin (Panlite L-1250) was used 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 -700■, the dark decay rate was 10.3%, the sensitivity was 2.4 Lux-sec, and the residual potential was -2.1■. .

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.

Table [Effects 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 charge retention ability under low to high temperatures 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 and R_2 represent a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and A represents a coupler residue having a phenolic hydroxyl group. X represents an oxygen atom or a sulfur atom, Y represents a direct bond or a vinylene group. Also, m and n represent 0 or 1, but at least one of m and n shall not be 0.) 2. Above The electrophotographic photoreceptor according to claim 1, wherein X in the general formula [I] is a sulfur atom. 3. 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_3, R_4, and R_5 are hydrogen atoms, substituted or unsubstituted alkyl groups, aralkyl groups, or aryl groups. ; 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.) 4. The photosensitive layer contains a carrier transporting substance and a carrier generating substance. and the carrier-generating substance has the general formula [I
] The electrophotographic photoreceptor according to claim 1, which is an azo compound represented by the following. 5. 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.