JPS61284769A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance light and the stability and carrier generating ability by forming a photosensitive layer containing a specified azo pigment on a coating solution on a conductive substrate. CONSTITUTION:The photosensitive body contains as an effective component of the electrophotographic sensitive one of the azo pigments represented by formula I in which A is a heterocyclic group, B is H, halogen, cyano, or the like, and Cp is a coupler resideu. The photosensitive body is prepared by coating the conductive substrate with a coating fluid obtained by dissolving or dispersing this pigment in a proper solvent, embodied by basis solvents dissolving tetraquisazo pigment, such as n-butylamine or ethylenediamine, and ethers, such as tetrahydrofuran and 1, 4-dioxane, and drying it to form a usually 0.1- several ten mum thick photosensitive layer. Said azo pigment has a particle diameter of <=5mum, preferably, <=3mum, and a binder is used usually in an amt. of 0.1-5 times the weight of the azo pigment, thus permitting heat and light stability and carrier generating ability to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (3) Field of Industrial Application The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo pigment.

More specifically, the present invention relates to a highly durable electrophotographic photoreceptor having high sensitivity and sensitivity up to the near-infrared region suitable for repeated use.

CB+ Prior Art and Problems Theretofore, as electrophotographic photoreceptors, those having a photosensitive layer mainly composed of an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide have been widely known.

However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In particular, selenium and cadmium sulfide have restrictions on manufacturing and handling due to their toxicity. there were.

On the other hand, an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as its main component must be relatively easy to manufacture. In addition, they generally have many advantages over selenium photoreceptors, such as superior thermal stability, and have attracted much attention in recent years.

Such organic photoconductive compounds include poly-N-
Vinylcarbazole is well known, and hereto 2.4
．． Electrophotographic photoreceptors which carry photosensitive Ml and which have as a main component a charge transfer complex formed with a Lewis acid such as 7-trinitro-9-fluorenone are not necessarily satisfactory in terms of sensitivity and durability.

On the other hand, in laminated or dispersed function-separated photoreceptors, in which the carrier generation function and the carrier transport function are assigned to separate substances, each material can be selected from a wide range, and the charging characteristics, sensitivity, and durability are improved. It has the advantage that an electrophotographic photoreceptor having arbitrary electrophotographic properties can be produced relatively easily.

Conventionally, various carrier-generating substances or carrier-transferring substances have been proposed.

For example, a carrier generation layer made of amorphous selenium and a void I
An electrophotographic photoreceptor having a photosensitive layer in combination with a carrier transport layer containing J-N-vinylcarbazole as a main component has been put into practical use.

However, a carrier generation layer made of anatomical selenium has a drawback of poor durability.

Furthermore, the use of organic dyes and pigments as carrier-generating substances has been proposed many times. Kaisho 52-424
Publication No. 1, Japanese Unexamined Patent Publication No. 1983-46558, Special Publication No. 1983
-11945-1! Publications etc. are already publicly known.

However, these azo pigments are not necessarily satisfactory in terms of characteristics such as sensitivity, residual potential, and stability when used repeatedly, and the selection range of carrier transfer substances is also limited. The reality is that nothing that fully satisfies the wide range of process requirements has yet been obtained.

(q) Purpose of the Invention An object of the present invention is to provide an electrophotographic photoreceptor containing an azo pigment that is stable against heat and light and has excellent carrier generation ability.

Another object of the present invention is to provide an electronic device with high sensitivity and low residual potential even in the visible and near-infrared regions, and whose characteristics do not change even after repeated use. The purpose of the present invention is to provide a photographic photoreceptor.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing an azo pigment that can effectively function as a carrier generating substance even in combination with a wide variety of carrier transfer substances.

■) Structure of the Invention As a result of intensive research to achieve the above object, the present inventors discovered that an azo pigment represented by the following general formula (IJ) can function as an active ingredient of a photoreceptor, and completed the present invention. This is what I did.

:I) (wherein A is a heterocyclic residue, B is hydrogen, halogen, cyano,
and Cp is a Kaglar residue. ) Specific examples of A and Cp in the above general formula are shown below.

A includes a pyrrole ring group, a pyrazole ring group, a pyrimidine ring group, an indole ring group, a pyridine ring group, an imidazole ring group, a benzimidazole ring group, a carbazole ring group, a thiophene ring group, a thiazole ring group, a benzothiazole ring group, Furan ring group, oxazole ring group, benzofuran ring group,
Examples include dibenzofuran ring group and benzoxazole ring group.

Substituted bases of each of these heterocyclic residues are also effective.

Examples of substituents include alkyl groups such as methyl and ethyl, alkoxy groups such as methoxy and ethoxy, aryl groups such as phenyl and tolyl, dialkylamino groups such as dimethylamino and diethylamino, halogen atoms such as chlorine and bromine, and cyano. Selected from the following groups.

Cp represents a residual group of a coupler that reacts with a diazo group, and a Caglar residue having a structure represented by the following general formula (I[l) is particularly effective.

'%, Y, / r, -y, i (where Yfl is fused with a benzene ring to form a polycyclic aromatic ring such as naphthalene or anthracene ring, or fused to a benzene ring to form a carbazole ring, penzocarno (zole ring, Indicates the atomic group necessary to form a heterocycle such as a dibendifuran ring.R1 is an optionally substituted alkyl group (e.g., methyl group, ethyl group, n-propyl group, 1so-propyl group, n-butyl group, 5ec-butyl group, amyl group,
1-octyl group, benzyl group, p-chlorobenzyl group,
3.4-dichlorobenzyl group, p-methylbenzyl group, 2-phenylethyl group, α-naphthylmethyl group, β-
naphthylmethyl group) aryl group (e.g. phenyl group, tolyl group, xylyl group, piphenyl group, chlorophenyl group, dichlorophenyl group, bromphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group,
Phenoxyphenyl group, nitrophenyl group, cyanophenyl group, hydroxyphenyl group, carboxyphenyl group, N,N-dimethylaminophenyl group, α, α, α-trifluoromethylphenyl group, methylthiophenyl group, α
-naphthyl group, β-naphthyl group, etc.) R2 is R1 and a heterocyclic group (e.g., thiazolyl group, 5-naphthyl group, etc.)
Nitrothiazolyl group, carbazolyl group, indolyl group,
pyrrolyl group, acridyl group, benzo(b)thiophenyl, benzimidazolyl group, oxasilyl group, chlorooxasilyl group, triazolyl group, piperidyl group, pyridyl group, quinolyl group).

R3 is 0. S, -Nu, "4, R5 is hydrogen,
Optionally substituted alkyl group, nitro group, methoxy group,
Indicates ethoxy group, acetyl group, cyano group, and halogen.

Z is a chain hydrocarbon necessary to form a 5-membered ring or a 6-membered ring. ) That is, in the present invention, by using the azo pigment represented by the general formula (1) as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, the advantages of the azo pigment of the present invention can be realized. The generation and transfer of carriers are performed using separate substances, respectively.

By using it as a carrier-generating material in so-called function-separated electrophotographic photoreceptors, it has excellent film properties, excellent electrophotographic properties such as charge retention, sensitivity, and residual potential, and is resistant to fatigue even when used repeatedly. It is possible to produce an electrophotographic photoreceptor that exhibits stable characteristics with little deterioration and whose characteristics do not change even when exposed to heat or light.

Specific examples of the azo pigment useful in the present invention represented by the general formula CI) include those having the following structural formula, but the azo pigment of the present invention is not limited thereto.

Exemplary Azo Pigment A tetravalent amino compound represented by the above general formula (1) (wherein A and B have the same meanings as in the previous section) is azo-ized by a conventional method, and then the corresponding coupler is is coupled in the presence of an alkali, or the diazonium salt of the above-mentioned tetravalent amino compound is isolated in the form of a borofluoride salt or a zinc chloride double salt, and then a suitable solvent (for example, N, It can be easily synthesized by coupling reaction with a coupler in N-dimethylformamide, dimethylsulfoxide, ethanol, dioxane) in the presence of an organic or inorganic alkali.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more azo pigments represented by the general formula (1). Although a photosensitive layer in the form of ridges is well known, the photosensitive layer of the electrophotographic photoreceptor of the present invention may be in any of these forms.

Usually, the photosensitive layer is of the type exemplified below.

■ A photosensitive layer made of an azo pigment ■ A photosensitive layer made of an azo pigment dispersed in a binder ■ A photosensitive layer made of an azo pigment dispersed in a well-known charge transfer substance The azo pigment represented by the above general formula generates charge carriers with extremely high efficiency when it absorbs light. Although the generated carrier can be transferred using an azo pigment as a medium, it is more preferable to transfer the carrier using a well-known loaded moving object 5it as a medium. From this point of view, photosensitive layers having the forms (1) and (2) are particularly preferred.

Charge transfer substances are generally classified into two types: electron transfer substances and hole transfer substances, but both can be used in the photosensitive layer of the photoreceptor of the present invention, and a mixture of substances having all the same functions can be used. Also, mixtures of materials having different functions can be used. Examples of substances that transfer electrons include electron-withdrawing compounds having electron-withdrawing groups such as nitro groups, cyano groups, and ester groups.
．． 4.7-Dolinitroneluorenone, 2.4,5.7-
nitrated fluorenones, such as titranitrofluorenone;
Or tetracyanoquinodimethane, tetracyanoethylene, 2,4,5.7-titranitroxanthone, 2.
Examples include compounds such as 4.8-) linitrothioxanthone, and polymerized versions of these electron-absorbing compounds.

Furthermore, examples of electron-donating organic photoconductive compounds that can be used as hole transport media include the following.

Hydrazones 2H5 2H5 Pyrazolines, diarylalkanes, alkylene diamines, dibenzylanilines C1) Triphenylamines, diphenylbenzylamines, triarylalkanes, oxadiazoles, anthracenes, oxazoles, and the like. Other polymer compounds
N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, polyglycidylcarbazole, polyvinylacenaphthylene, ethylcarbazole-formaldehyde resin, etc. can also be used.

The carrier transfer substance is not limited to those described here, and when used, carrier transfer substances t-1m or 2aI or more can be used in combination.

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

For example, an electrophotographic photoreceptor having a photosensitive NI of the type (2) above is prepared by dissolving or dispersing the azo pigment represented by the general formula (I) in a suitable medium. It is applied and dried, usually several 0.1 μm to several 1 μm.
It can be manufactured by forming a photosensitive layer with a thickness of 0 μm.

Examples of media for preparing the coating solution include basic solvents that dissolve tetrakisazo pigments such as n-butylamine and ethylenediamine; ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; toluene and xylene. Aromatic hydrocarbons such as N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, etc.Aprotic polar solvents such as methanol, ethanol, ingropanol, etc.Alcohols: ethyl acetate, methyl acetate, methyl Examples include media for dispersing azo pigments, such as esters such as cellosolve acetate, dichloroethane, and chlorinated hydrocarbons such as chloroform.

When using a medium for dispersing the azo pigment, the particle size of the azo pigment is 5 μm or less, preferably 3 μm or less, and optimally 1 μm or less.
It is necessary to make the particles smaller than μm.

Furthermore, as the conductive support on which the photosensitive layer is formed, any of those employed in well-known electrophotographic photoreceptors can be used.

Specifically, for example, a metal drum made of aluminum, copper, etc.
Examples include sheets, laminates and vapor deposits of these metal foils.

Further examples include glass films, plastic drums, paper, etc. which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder to conductivity treatment.

Other examples include plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

If a binder is dissolved in the coating liquid used to form the photosensitive layer of the type (2) above, an electrophotographic photoreceptor having the photosensitive layer of the type (2) above can be produced.

In this case, the medium of the coating liquid is preferably one that dissolves the binder.

As binders, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic esters, methacrylic esters, phenoxy resins, polysulfones, arylate resins, polycarbonates, polyesters,
Examples include various polymers such as cellulose ester, cellulose ether, urethane resin, epoxy resin, and acrylic polyol resin.

The amount of binder used is usually 0°1 to 5% relative to the azo pigment.
The range is twice the weight.

In addition, in forming this type of photosensitive layer,
It is preferable that the tetrakisazo pigment is present in the binder in the form of fine particles, for example, with a particle diameter of 3 μm or less, particularly 111 m or less.

Similarly, by dissolving a charge transfer medium in the coating liquid used to form the photosensitive layer of the type (2) above, an electrophotographic photoreceptor having the photosensitive layer of the type (2) above can be manufactured.

As the charge transfer medium, any of those exemplified above can be used.

Apart from charge transport media which can themselves be used as binders, such as polyvinylcarbazole and polyglycidylcarbazole, it is preferred to use other binders.

As the binder, any of those exemplified above can be used.

In this case, the binder used i is usually 5 for the azo pigment.
~1000:i amount times the amount, and the amount of the charge transfer medium used is normally 0.2 to 3.0 times the binder weight,
Preferably it is in the range of 0.63 to 1.2 times by weight. In the case of a charge transport medium which itself can be used as a binder, it is usually used 5 to 10 times the weight of the azo pigment.

In this type of photosensitive layer, as in the above-mentioned type 2 photosensitive layer, it is preferable that the bisazo pigment is present in the charge transport medium and the binder in the form of fine particles.

If a coating solution obtained by dissolving a charge transfer medium in a suitable medium is applied onto the photosensitive layer of the types ① to ① above and dried to form a charge transfer N, an electron beam having the photosensitive layer of the type ① can be formed. Photographic photoreceptors can be manufactured.

In this case, the photosensitive layers of types (1) to (4) above serve as charge generation layers. The charge transfer layer does not necessarily need to be provided above the charge generation layer, but may be provided between the charge generation layer and the conductive support.

However, the former is preferable in terms of durability.

The charge transfer layer is formed in the same manner as the photosensitive layer described in (2) above. That is, the coating liquid for forming the photosensitive layer described in (1) above, except that the azo pigment is removed, may be used as the coating liquid.

Typically the charge transport layer is 5-50 μm thick.

Of course, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known sensitizer.

Suitable sensitizers include Lewis acids and dyes that form charge transfer complexes with organic photoconductive materials.

Examples of Lewis acids include quinones such as chloranil, 2,3-dichloro-1,4-naphthoquinone, 2-methylanthraquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-chloroanthraquinone, and phenanthrenequinone. aldehydes such as 4-nitrobenzaldehyde, 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone%
Ketones such as 313'15.5'-tetranitrobenzophenone, acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, tetracyanoethylene, terephthalmalondinitrile, 4-nitrobenzalmalononitrile, etc. Cyano compounds: Examples include electron-withdrawing compounds such as 3-benzalphthalide, 3-(a-cyano-p-nitrobenzal) phthalide, and 3-(α-cyano-p-nitrobenzal) phthalides.

Examples of dyes include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, pyrylium salts, thiapyrylium salts, and benzopyrylium salts.

In addition, inorganic photoconductive fine particles such as selenium and selenium-arsenic alloys, and organic photoconductive pigments such as copper-7 talocyanine pigments and perylene pigments may be entirely contained.

Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer in order to improve film formability, flexibility, and mechanical strength. As plasticizers, metal acid esters,
sic acid ester, epoxy compound, chlorinated paraffin,
Examples include aromatic compounds such as chlorinated fatty acid esters and methylnaphthalene.

Furthermore, it is not necessary to include an adhesive layer, an intermediate layer, and a transparent insulating layer as necessary.

The photoreceptor using the azo pigment of the present invention has high sensitivity and good color sensitivity, and when used repeatedly, there is little change in sensitivity and chargeability, little light fatigue, and extremely high durability. It is something that

Furthermore, the photoreceptor of the present invention can be widely used in electrophotographic applications such as photoreceptors and printing plates for printers using lasers, cathode ray tubes (CRTs), and light emitting diodes (LEDs) as light sources in addition to electrophotographic copying machines.

(2) Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Polyester film laminated with aluminum foil (Alpet 85 manufactured by Daido Kako, aluminum film thickness 10 μm)
) on a conductive support consisting of vinyl chloride; vinyl acetate: maleic anhydride copolymer (Eslec MF-
10) Adhesive undercoating Nt shadow formation with a thickness of 0.05 μm,
Exemplary azo pigment shop 48 22 and polyarylate resin (Unitika U-100) 2 and 1,2-dichloroethane Z
o.

- In addition to this, an azo pigment dispersion obtained by dispersing it in a Paintco/Digi mixer for about 1 hour is applied and dried on the intermediate layer so that the film thickness after drying is 0.3 μm to form a carrier generating layer. and further carrier transfer substances N, N-
Dibenzylaminobenzaldehyde-1,1-diphenylhydrazone 5f7 Along with 7t of polyarylate resin, 1
, 2-dichloroethane (50 tnt) was coated and dried to form a carrier transport layer, and an electrophotographic photoreceptor of the present invention was prepared.

After storing this photoreceptor at room temperature at 30°C in a dark place for - weeks, it was tested using an electrostatic paper tester 1'-8P-428'' (
(newly manufactured by Kawaguchi Electric) and conducted the following characteristic tests.

That is, a voltage of -6 KV is applied to the charger to cause corona discharge for 5 seconds. ! -Potential V at the time of charging
o(-V), then the illuminance at the surface of the photosensitive layer is 301u
The exposure amount B-H (lux @ second) required to attenuate the surface potential of the photosensitive layer to i 1/2 was determined by irradiating the photosensitive layer with light from a halogen lamp in a state where x was reached. In addition, the surface potential after exposure with an exposure amount of 301 ux/second, that is, the residual potential B
so(V) was determined. Similar measurements were repeated a total of 500 times. In addition, irradiation exposure was further performed for 0.3 seconds at 300 lux using a tungsten lamp as a light source to eliminate residual potential, so that the residual potential was completely reduced to zero.

The results are shown in Table 1.

Table 1 Examples 2 to 6 Azo pigments each exemplified as a carrier generating substance 5.17
．． A total of five types of electrophotographic photoreceptors of the present invention were prepared in the same manner as in Example 1 except that 70.79,94 was used.
Similar characteristic tests were conducted for each of them. The results are shown in Table 2.

Example 7 An intermediate layer of butyral resin (polymerization degree of about 700, manufactured by Wako Pure Chemical Industries, Ltd.) with a thickness of 0.02 μm was formed on the outer surface of a drum made of aluminum and had a diameter of 60 mm, and exemplified azo pigment 4 was formed.
A dispersion obtained by dispersing 902 ft of polyarylate resin 2 fg dissolved in 100 g of tetrahydrofuran and a paint conditioner for about 3 hours was applied onto the intermediate layer so that the film thickness after drying was 0.5 μm. The coating was applied and dried to form carrier generation/Itl''. On this carrier generation layer, p-diethylaminobenzaldehyde-1-
Methyl-(4'-methoxyphenyl)hydrazone 10?
and polycarbonate resin (manufactured by Konjin) Kunlite L-1
250) 1,2-dichloroethane 100- with 12F
A solution dissolved in the above was applied and dried to a film thickness of 15 μm after drying to form a carrier transfer layer, thereby producing a drum-type electrophotographic photoreceptor according to the present invention.

When this electrophotographic photoreceptor was installed in our modified commercially available cartridge-type electrophotographic copying machine and a copied image was formed, a clear visible image with high contrast and faithful to the original was obtained.

Further, although copying was repeated 11,000 times, a visible image equivalent to that of the first copy was obtained until the end.

Example 8 The reflection spectrum of the drum electrophotographic photoreceptor obtained in Example 7 was measured using a spectrophotometer equipped with an integrating sphere (Shimadzu UV-365).
), and it was found that the maximum absorption wavelength of this photoreceptor in the visible region was around 660 nm and 770 nm.

Furthermore, the spectral sensitivity of this photoreceptor between 500 nm and 850 nm was measured using a monochromator, and the results are shown in FIG.

Light-emitting diode, semiconductor laser, He-N as a light source
It was found that the photoreceptor has sufficient practical sensitivity even when an e-laser is used.

Example 9 Styrene:n-butyl methacrylate:methacrylic acid copolymer (styrene:n
-Butyl methacrylate; 1:2 weight ratio, acid value 250)
and Exemplary Azo Pigments 48 and N.

N-diethylaminobenzaldehyde-1-phenyl-
1-Ethylhydrazone t-1,5: A weight ratio of 0.25 was blended, and this was dissolved in dioxane (resin component hydrazone compound) dispersed (azo pigment), coated with gold, dried, and single-layer photosensitive with a film thickness of 5 μm. The body was subjected to a shimiko photographic property test using the electrostatic paper tester described above.

Applied voltage +6KV Vo=510Volt E”=6.21ux@s
It was ec.

In addition, this photoreceptor is visualized with a developer (toner), and then an alkaline processing aqueous solution (for example, 3% triethanolamine, 10% ammonium carbonate, 15% average molecular weight 190
When treated with ~210 polyethylene glycol-5-benzyl alcohol), toner-free areas are easily eluted;
Next, by washing with water containing sodium silicate, a printing original plate could be easily prepared.

When offset printing is performed using this original plate, it has been found that it can withstand printing of approximately 100,000 sheets.

In addition, in order to obtain a toner visible image (light source: halogen rung)
Direct plate making was carried out using an optimum exposure amount of 150 lux m sec, and no base material was used when creating the original printing plate.

[Brief explanation of drawings]

FIG. 1 is a spectral sensitivity curve of the photoreceptor of the present invention in Example 8.

Claims (2)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula (I) on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, A is a heterocyclic residue, B is hydrogen, halogen, or cyano, and Cp is a coupler residue.) (2) The electrophotography according to claim 1, wherein the photosensitive layer contains a carrier transfer substance and a carrier generating substance, and the carrier generating substance is an azo pigment represented by the general formula (I). Photoreceptor.