JPH01198763A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body which is excellent in both sensitivity and durability by providing a photosensitive layer contg. a specific bisazo compd. on a conductive base. CONSTITUTION:This electrophotographic sensitive body has the photosensitive layer contg. the bisazo compd. expressed by the formula I on the conductive base. The bisazo compd. expressed by the formula I has the high generation efficiency of charge carriers and carrier implantation efficiency to a charge carrier transfer medium and has the excellent performance as a charge carrier generating material of separated function type photosensitive bodies of a laminated type and single-layer type. The electrophotographic sensitive body contg. the bisazo compd. has the high sensitivity and good color sensitivity and is particularly low in photofatigue; therefore, the fluctuation in the sensitivity, electrostatic chargeability and residual potential is decreased and the high stability and excellent durability are obtd. when said body is repeatedly used.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor. Specifically, the present invention relates to a highly sensitive electrophotographic photoreceptor containing a novel bisazo compound.

<Prior art> Photoreceptors for electrophotography have traditionally been made of inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide, but recently, non-polluting materials have been used. Organic photoconductors have many advantages, including ease of manufacture and handling, good image quality, and the ability to easily obtain photoreceptors in various shapes such as drums, sheets, and belts. The so-called OPC photoreceptor using a compound (hereinafter abbreviated as [OPCJ)] is being adopted for plain paper copying machines and printers, and the proportion thereof is increasing year by year.

<Problem to be solved by the invention> Although OPC photoreceptors have many of the above-mentioned advantages than conventional inorganic photoreceptors, they are inferior in sensitivity and durability, and are currently the only It is used in the field of low-speed aircraft.

Therefore, it is desired to develop an OPC with excellent sensitivity and durability.

Means for Solving the Problems The present inventors have conducted intensive studies on a new OPC in order to obtain a highly sensitive and highly durable electrophotographic photoreceptor.
The present invention was achieved by discovering that a specific bisazo compound is suitable.

That is, the gist of the present invention is that the following formula [l] or [1']...[1'] (where K1 and K2 represent a hydroxyl group having a coupling ability) is formed on a conductive support. represents a coupler residue containing, even if K1 and K2 are the same,
May be different. ) The present invention will be described in detail below.

The bisazo compound used in the electrophotographic photoreceptor of the present invention has a structure represented by formula (1) or [I] above.

In the general formulas [l] and [1], K1 and K2 may be any coupler residues containing a hydroxyl group having coupling ability, for example, the following general formulas [11] to [■]
is given as a preferable example.

Note that the hydroxyl group having coupling ability refers to a group that imparts the property of being able to couple with a diazonium salt to an aromatic ring or the like to which the hydroxyl group is bonded.

In formula CI, X is fused with a benzene ring to form a polycyclic aromatic ring such as a naphthalene ring, an anthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, a diphenylene sulfide ring, or a petero ring. The residues required for Also, R2 and R3
is a hydrogen atom: an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, which may have a substituent; an aralkyl group such as a benzyl group, phenethyl group, or naphthylmethyl group; aryl groups such as phenyl, diphenyl, and naphthyl groups; heterocyclic groups such as carbazole groups, dibenzofuran groups, benzimidacylon groups, benzthiazole groups, thiazole groups, and pyridine groups; or a bond between R2 and R3. Indicates that a monovalent amine group is formed together with a nitrogen atom. R2 and R3 may be the same group or different groups, but from the viewpoint of sensitivity, it is preferred that one be a hydrogen atom and the other be a group other than a hydrogen atom.

84 R4 In formulas [厘] and (IV), R4 represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent as shown in the same examples as R2 and R3.

OHOH formula [V-a], (v-b), (Vl-a), (Vl-b
], Y represents a divalent group of an aromatic hydrocarbon or a covalent group of a heterocycle containing a nitrogen atom in the ring. As a monovalent group of an aromatic hydrocarbon, '' is, for example, a monovalent group of a monocyclic aromatic hydrocarbon such as a θ-phenylene group; a naphthylene group, a peri-
Naphthylene group, /, J-anthraquinonylene group, 9,1
Examples include monovalent groups of condensed polycyclic aromatic hydrocarbons such as 0-phenanthrylene group.

Further, examples of monovalent heterocyclic groups containing a nitrogen atom in the ring include 3. ! -Pyrazolediyl group, Co, 3-pyridinediyl group, S, S-pyrimidinediyl group, 6,7-
Indazolediyl group! ;, A-benzimidazolediyl group, 6,7-chiralindiyl group, etc., S to 10-membered ring nitrogen atoms, preferably heterocyclic monovalent groups containing - nitrogen atoms or less in the ring, etc. .

When considering sensitivity and durability, Y includes O-phenylene group, O-naphthylene group, peri-naphthylene group,
Co, 3-pyrimidinediyl group, 9,j-pyrimidinediyl group, particularly preferred are O-phenylene group and O-naphthylene group.

In the present invention, these aromatic hydrocarbon monovalent groups and heterocyclic monovalent groups containing a nitrogen atom in the ring used as Y may have a substituent.

Such substituents include, for example, methyl group, ethyl group,
n-propyl group, i-propyl group, n-butyl group, l-
Alkyl groups such as butyl group and n-hexyl group; alkoxy groups such as methoxy group, ethoxy group, phenoxy group, butoxy group; hydroxyl group; nitro group; cyano group; amino group; dimethylamino group, diethylamino group, dibenzylamino group Substituted amine groups such as groups; halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; carboxyl group; alkoxycarbonyl group such as ethoxycarbonyl group; carbamoyl group; aryloxy group such as phenoxy group; benzyloxy group etc. Arylalkoxy group; includes aryloxycarbonyl groups such as phenyloxycarbonyl group. Among them, alkyl groups, alkoxy groups, nitro groups, halogen atoms, hydroxyl groups, carboxyl groups, particularly methyl groups, methoxy groups, nitro groups, chlorine atoms, and hydroxyl groups are preferred.

Incidentally, a compound having a group of the formula [V-a] type is usually represented by the formula (
Since it often exists as a mixture with an isomer having a group of the formula (V-b) type, in the present invention, when a group of the formula [V-a) type is shown, it has a type of the formula (V-b) type. Represents a mixture with a compound.

Further, the formula (Vl-a) type also represents a mixture with a compound having a group of the formula (Vl-b) type.

The bisazo compound used in the present invention is, for example, the following formula [
It can be easily synthesized by tetrazotizing a diamine represented by [■] or [■'] by a conventional method and coupling it with a corresponding coupler.

When the coupler residues K" and K" in formula [I] are different from each other, corresponding C-like couplers may be mixed and used.

Such a coupling reaction is usually carried out according to a known method.
The reaction may be carried out in water and/or an organic solvent such as dimethylformamide or dimethyl sulfoxide at a reaction temperature of 30° C. or less for about 7 to 10 hours.

The aromatic diamine represented by the above-mentioned formula [■] or [black] can be produced, for example, according to the following reaction formula.

[■]

[V'] [■] To explain the above reaction formula in detail, for example, in a solvent such as nitrobenzene acetate, naphthalene-tetracarboxylic anhydride and nitro-ortho-phenylenediamine are condensed, Next, reduction is carried out under known combination conditions of iron powder, zinc or tin chloride and a solvent such as hydrochloric acid or acetic acid.
The above compound [■] or [■'] can be produced in good yield.

The electrophotographic photoreceptor of the present invention has the above general formula [I] or [I
It has a photosensitive layer containing one or more bisazo compounds represented by the following. Various types of photosensitive layers are well known, and the photosensitive layer of the present invention may be of any of these types. Particularly preferred is a method in which the bisazo compound of the present invention is used as a charge carrier generation material, dispersed in a binder, the resulting layer is used as a charge generation layer, and a charge transfer layer containing a known charge carrier transfer medium is laminated thereon. Examples include a laminated type photoreceptor and a single layer type photoreceptor in which a well-known charge carrier transfer medium is added to a dispersion layer of the above-mentioned bisazo compound.

The bisazo compound represented by the above general formula [I] or [I'] of the present invention has high charge carrier generation efficiency and carrier injection efficiency into the charge carrier transfer medium, and has a high charge carrier generation efficiency and a high carrier injection efficiency into the charge carrier transfer medium. It has excellent performance as a charge carrier generating material for photoreceptors.

Charge carrier transfer media used in combination with the bisazo compound of the present invention are generally classified into two types: electron transfer media and hole transfer media, and both can be used in the photoreceptor of the present invention, and mixtures thereof can be used. can also be used. As an electron transfer medium, an electron-withdrawing compound having an electron-withdrawing group such as a nitro group, a cyan group, or an ester group, a domestic dog rd
J,4',? -) linitrofluorenone, J + f
＋! ; Examples include nitrated fluorenone such as t7-titranitrofluoreno7, or tetracyanoquinodimethane. In addition, as a hole transfer medium, electron-donating organic photoconductive compounds such as polycyclic compounds such as carbazole, indole, imidapool, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, and thiadiazole; triphenylmethane, etc. Triarylalkane derivatives; triarylamine derivatives such as triphenylamine; phenylenediamine derivatives; N-phenylcarbasol derivatives; stilbene derivatives; hydrazone compounds, etc., and in particular, dialkylamino groups,
Examples include compounds with large electron-donating properties substituted with substituted amino groups such as diphenylamino groups, electron-donating groups such as alkoxy groups and alkyl groups, or aromatic ring groups substituted with these electron-donating groups. . Also included are polymers such as polyvinylcarbazole that have a group consisting of these compounds in the main chain or side chain. Among these, hydrazone compounds are as follows: R5 and R6 are, for example, an alkyl group such as a methyl group or an ethyl group; an aryl group such as a phenyl group or a naphthyl group; or an aralkyl group such as a benzyl group, and at least seven of R6 and R6 are aryl groups. A hydrazone compound represented by the following formula is particularly suitable:

The electrophotographic photoreceptor of the present invention can be manufactured according to a conventional method.

That is, the electrophotographic photoreceptor of the present invention may be a laminated type having a charge generation layer and a charge transfer layer containing a bisazo compound on a conductive support, or a single layer type having a photosensitive layer in which a bisazo compound is dispersed. In addition to these, intermediate layers such as an adhesive layer and a blocking layer, and layers for improving performance such as electrical properties and mechanical properties, such as a retention layer, may be provided.

As the conductive support, any of those employed in well-known electrophotographic photoreceptors can be used.

Specific examples include metal drums and sheets made of aluminum, copper, etc., and laminates and vapor deposits of these metal foils. Furthermore, plastic films are coated with conductive substances such as metal powder, carbon black, iodized steel, and polymer electrolytes along with a suitable binder to conductivity treatment.
Examples include plastic drums and paper. Other examples include plastic films that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

In the stacked type photoreceptor described above, a charge generation layer is usually formed on a conductive support, and a charge transfer layer is formed thereon, but the opposite structure may be used.

The charge generation layer is formed by applying and drying a coating solution containing the bisazo compound of the present invention and a binder polymer. Although the bisazo compound may be dissolved, it is usually applied as a dispersed coating liquid. As a solvent for preparing the coating solution, basic solvents such as butylamine and ethylenediamine;
Ethers such as tetrahydrofuran, /, lI-dioxane; Ketones such as methyl ethyl ketone and cyclohexanone; Aromatic hydrocarbons such as toluene and xylene; N, N
- Aprotic polar solvents such as dimethylformamide, acetonitrile, N-methylpyrrolidone, and dimethyl sulfoxide; Alcohols such as methanol, ethanol, and isopropanol; Esters such as ethyl acetate, methyl formate, and methyl cellosolve acetate; dichloroethane, chloroform Examples include chlorinated hydrocarbons such as.

When dispersing a bisazo compound, it is necessary to adjust the particle size to 1 μm or less, preferably θ, Sttm or less.

Examples of binders include polymers and copolymers of novinyl compounds such as styrene, vinyl acetate, acrylic esters, methacrylic esters, vinyl alcohol, and ethyl vinyl ether, phenoxy resins, polysulfones, polyvinyl acetals, polycarbonates, polyesters, polyamides, polyurethanes, and cellulose. Examples include esters, cellulose ethers, epoxy resins, silicone resins, and the like.

The ratio of the bisazo compound of the present invention to the binder polymer is not particularly limited, but generally, the ratio of the bisazo compound to the binder polymer is 1 to 1.
5 to SOθ parts by weight, preferably 20 parts by weight based on 0θ parts by weight
~300 parts by weight of binder polymer is used.

In addition to this, the above coating solution also contains dispersion stabilizers, coating properties improvers,
Furthermore, dyes, electron-withdrawing compounds, and other additives may be added to improve performance. The thickness of the charge generation layer is O
0θS-Sμm1 preferably 007 to 24m.

Seven or more kinds of charge carrier transport media are dissolved in the coating solution for the charge generation layer, and the ratio of the dry binder polymer and the charge carrier transport medium is usually such that the binder polymer is in proportion to the lo'N part of the bisazo compound. io~
/θQθ parts by weight preferably 30-500 parts by weight, and the charge carrier transfer medium ° is 5-iooo parts by weight, preferably 20-SOO parts by weight.

In a laminated photoreceptor, a charge transfer layer is formed by applying a coating liquid containing a charge carrier transfer medium onto the charge generation layer and drying the coating liquid. When the charge carrier transfer medium is a polymeric compound that has a tendency to form a film, it is not necessary to use a binder polymer, but it may be mixed in order to improve flexibility or the like.

In the case of low molecular weight compounds, a binder polymer is used for film formation. As the binder polymer, those mentioned above are used, and the amount used is usually in the range of go to 300 θ parts by weight, preferably 70 to 1000 parts by weight, based on ioo parts by weight of the charge carrier transfer medium.

In addition to the above, various additives can be used in the charge transfer layer in order to improve performance and improve the mechanical strength and durability of the coating film.

Such additives include electron-withdrawing compounds, pigments,
Stabilizers such as ultraviolet absorbers and antioxidants, coating improvers,
Examples include plasticizers and crosslinking agents.

Examples of electron-withdrawing compounds include chloranil, co-, 3-
Dichloro/, lI-naphthoquinone, comethylanthraquinone, /-nitroanthraquinone, l-chloro-5
-nitroanthraquinone, cochloroanthraquinone,
Quinones such as phenanthrenequinone; aldehydes such as dernitropenzaldehyde; ketones such as 9-benzoylanthracene, indanedione, 3,3-dinitrobenzophenone, J t 3't j z j'-tetranitrobenzophenone; anhydrous Acid anhydrides such as phthalic acid, dichloronaphthalic anhydride, polytetracyanoethylene,
Cyano compounds such as terephthalalmalononitrile, danitropenzalmalononitrile, 17-benzoyloxybenzalmalononitrile, "(p-nitropenzoylo,xy)benzalmalononitrile;3-benzalphthalide,"y (α-cyano -p-nitrobenzal)
Phthalide, 3-(α-cyano-p-nitrobenzal)
Examples include phthalides such as -II, b, and q-tetrachlorophthalide.

<Effects of the Invention> The electrophotographic photoreceptor containing the bisazo compound of the present invention has high sensitivity and good color sensitivity, and has particularly low optical fatigue, so that when used repeatedly, sensitivity, chargeability, and residual potential decrease. It is highly stable, with little fluctuation in temperature, and has extremely high durability.
The photoreceptor is also suitable for photoreceptors for printers such as laser printers, liquid crystal printers, shutter printers, and LED printers, which particularly require performance stability and reliability.

<Examples> Next, the present invention will be explained in more detail with reference to Reference Examples and Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

In addition, in the reference examples and examples, [parts] indicate [parts by weight].

Reference example Naphthalene u, s, g-tetracarboxylic anhydride/
3. Cordiaminobenzene/to part q and Darnitro
'1. Part A was stirred in a mixed solvent of 50 parts of acetic acid and 100 parts of nitrobenzene, and reacted under reflux for S hours. After the reaction, the reaction mixture was cooled to room temperature, and the precipitated crystals were collected in a furnace, thoroughly washed with methanol, and then dried to obtain orange crystals 24 (Part J).

The melting point of the obtained condensate was 300°C or higher.

The condensate was then mixed with tin chloride,
It was reduced with hydrochloric acid to obtain brown crystals. The melting point of the obtained crystal was 300° C. or higher, and elemental analysis and mass spectrometry revealed that it was a mixture of the following 1. The yield was 22.7 parts.

The elemental analysis values were as follows.

Calculated value as C211H1402N6: (::tO031tIb%H,7,/9%
, N/ff, 99% actual measurement value: C70,! ;2%%H3
,22'lb, N/ff,? f% above diaminco θ
1 part was added to 690 parts of water and 230 parts of conc.

Next, 37.9 parts of aqueous difluoroboric acid solution was added to the liquid, and after stirring at 5°C or lower for 1 hour, the precipitated crystals were filtered, washed with a small amount of cold water, then with cold methanol, and dried to obtain the tetrazonium salt/J , part f was obtained. Dissolve 6 g of the tetrazonium salt in 200 parts of dimethyl sulfoxide, add this to a solution of 11 parts of the following compound dissolved in 1 soo part of dimethyl sulfoxide, and then add 11 parts of sodium acetate to 25 parts of water to the reaction system.
The dissolved liquid was added to the mixture, and stirring was continued for an additional 3 hours to collect precipitated crystals.

Next, the obtained bisazo compound was mixed with water, methanol,
It was washed with tetrahydrofuran and then dried. The obtained solid had a blackish-purple color and did not melt at temperatures below 30°C. Elemental analysis values and infrared absorption spectra (first
Figure) The yolk was identified as a mixture of bisazo compounds listed below. The yield was 9 parts, and the elemental analysis values were as follows.

Calculated value as C,, H, O, N□2: (:'!7.2.617%% H3,13%,
N/3.37% actual value 207, 52%, H3J flat,
N/, 7.4'/% The bisazo compound used in the following examples was synthesized by this reference example or a method similar to this, and similarly to this reference example, it was a mixture of isomers. It is.

Example/~g9 [l]' The bisazo compound o having a structure corresponding to the above-mentioned formula [l] or [l]'
Lupentanone (manufactured by Mitsubishi Chemical Corporation) was dispersed in a sand grinder with 30 parts, and polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., trade name: SURETSUK BH-, 7) and phenoxy resin (Union Carbide Co., Ltd. f) were dispersed in a sand grinder.
0.2 parts of each of f and i (product name: DKHH) were added and dissolved. The resulting bisazo compound dispersion was heated to a thickness of 7
A wire bar was used to deposit a dry film thickness of 06-g/n on the aluminum vapor-deposited layer deposited on a 5-μm polyester film.
After coating, it was dried. N-ethylcarbazole-3-aldehyde diphenylhydrazone qo moiety, ecp-nitrobenzoyloxy)benzalmalononitrile λ moiety, and polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd.) were deposited on the charge generation layer thus obtained. , trade name: Kneepilon E-2000) / 00 parts dissolved in t 7θ dioxane≠kiki part to a dry film thickness of 13
A charge transfer layer was formed by applying the coating to a thickness of .mu.m. In this way, an electrophotographic photoreceptor having a two-layer photosensitive layer was obtained.

Table 1 shows the values of half-decreased exposure (E, /2) as the sensitivity of these photoreceptors.

The half-decrease exposure amount was measured using an electrostatic copying paper tester (Model 5P-U Cog manufactured by Kawaguchi Electric Manufacturing Co., Ltd.) using the photoreceptor. First, charge it by corona discharge of -A,j KV in a dark place,
Next, it was exposed to white light at an illuminance of s lux, and the amount of exposure required for the surface potential to attenuate to half of the initial surface potential was determined.

bow

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum diagram of the bisazo compound synthesized in Reference Example.

Claims (1)

[Claims] (1) The following general formula [I] or [I
′] ▲There are mathematical formulas, chemical formulas, tables, etc.▼……[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼……[I ′] (In the formula, K^1 and K^2 have coupling ability A photoreceptor for electrophotography, characterized by having a photosensitive layer containing a bisazo compound (representing a coupler residue containing a hydroxyl group, and K^1 and K^2 may be the same or different). .