JPS6184654A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity, to reduce residual potential, to prevent these characteristics from change due to repeated uses, and to enhance durability by incorporating a specified azo compd. in a photosensitive layer. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains an azo compd. represented by the formula in which A is a divalent residue having C combining both N forming azo group, and Z is an atomic group necessary for forming an aromatic hydrocarbon ring or hetero ring or unsatd. monocyclic hydrocarbon ring. Such an azo compd. is used for the photoconductor constituting the photosensitive layer of the photosensitive body, or, especially, only as the excellent carrier generating material of a so-called functionally separated type photosensitive body using two separate materials of this azo compd. for generating carriers and another material for transferring them, thus permitting the physical film properties to be improved, electrostatic charge retentivity and sensitivity to be enhanced, residual potential and fatigue deterioration of the photosensitive body due to repeated uses to be reduced, and moreover, these characteristics to be not changed against heat and light and excellent stability to be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo compound. The present invention relates to a highly durable electrophotographic photoreceptor suitable for use.

BACKGROUND ART Conventionally, electrophotographic photoreceptors having a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide have been widely known.

L or Ll These are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. Furthermore, selenium and cadmium sulfide are toxic, so there are restrictions in manufacturing and handling. .

On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, and easy to handle, and generally compared to selenium photoreceptor G; L1 has attracted a lot of attention in recent years, as it has many advantages such as excellent thermal stability.

Poly-N-vinylcarbazole is well known as such an organic photoconductive compound, and 2.4.
7- An electrophotographic photoreceptor having a photosensitive layer mainly composed of a charge transfer complex formed from a Lewis acid such as trinitro-9-fluorenone is not always satisfactory in terms of sensitivity and durability. do not have.

On the other hand, there is a wide range of materials to choose from for functionally separated photoreceptors, such as laminated or dispersed types, in which the carrier generation function and the carrier transport function are assigned to separate substances, respectively.
It has the advantage that it is relatively easy to produce an electrophotographic photoreceptor that has all of the characteristics of Niji in terms of electrophotographic properties such as charging properties, sensitivity, and durability.

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

For example, a carrier generation layer made of amorphous selenium and a
? II - A photosensitive layer containing N-vinylcarbazole as the main component and a Lu1-Yaria transfer layer? An electrophotographic photoreceptor having the above-mentioned method has been put into practical use.

However, is the carrier generation layer made of amorphous selenium inferior in durability? ! - have.

In addition, various proposals have been made to use organic dyes and pigments as carrier generators. Publication, JP-A-52-
4241, JP-A-54-46558, JP-A-56-1)945, etc. are already known.

However, these azo compounds have poor characteristics such as sensitivity, residual potential, and stability when used repeatedly.
The reality is that it is not always possible to satisfy the wide range of requirements of the electrophotographic process, and the selection range of gear 1) a transfer substances is also limited.

FC+ OBJECT OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor containing an azo compound that is stable to heat and light and has excellent carrier generation ability.

Another object of the present invention is to have high sensitivity and low residual potential.
Another object of the present invention is to provide a highly durable photoreceptor whose characteristics do not change even after repeated use.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing an azo compound that can effectively act as a carrier generating substance even when combined with a wide variety of gear transfer substances. .

(Dl Structure of the Kaimei As a result of intensive research to achieve the above object, the present inventors discovered that an azo compound represented by the following general formula (1) can act as an active ingredient of a photoreceptor, and have developed the present invention. It is completed.

-F functional formula (1) (in the formula, A is a divalent residue bonded to the N atom forming an azo with the C atom, and Z is a substituted or unsubstituted carbocyclic aromatic ring or , a group of atoms necessary to form a substituted or unsubstituted aromatic ring or an unsaturated monocyclic hydrocarbon ring.) In other words, in the present invention, By using the azo compound of the present invention as a photoconductive substance constituting the entire photosensitive layer of an electrophotographic photoreceptor, the excellent carrier generation ability of the azo compound of the present invention is fully utilized. By using it as a carrier generating material in so-called function-separated electrophotographic photoreceptors, each of which is made of separate substances, it has excellent film properties, excellent electrophotographic properties such as charge retention, desensitization, and residual potential, and can be used repeatedly. It is possible to produce an electrophotographic photoreceptor that exhibits stable characteristics, with little deterioration caused by fatigue, and the above-mentioned characteristics do not change even when exposed to heat or pressure.

Specific examples of the useful azo compounds of the present invention represented by the general formula (1) include those having the following structural formula, but the azo compounds of the present invention are not limited thereto. .

Exemplary Compound F3 The azo compound represented by the general formula (1) is represented by the general formula H,
A diamine represented by N-A-NH (where Aμ has the same meaning as above) is tetrazotized by a conventional method, and then a corresponding coupler is coupled in the presence of an alkali, or
Alternatively, once the tetrazonium salt of the diamine is released in the form of a fluoroborate salt or a zinc chloride salt, it is dissolved in a suitable solvent such as N.

It can be easily synthesized by coupling with a G coupler in the presence of an alkali in a solvent such as N-dimethylformamide or dimethylsulfoxide.

Next, a method for synthesizing representative examples of the azo compound used in the present invention will be shown.

Synthesis example (exemplified compound A5) 3.3'-dichlorobenzidine 3.810.015mo
le)t? Add and disperse in a mixture of 3.5 WLl of concentrated hydrochloric acid, 20 ml of water, and 20 ml of dimethyl sulfoxide, and dropwise add a solution of 2.76 P (0.04 mole) of sodium nitrite dissolved in water under ice cooling. The mixture was allowed to react for about 1 hour under cooling. Next, activated carbon was added and the mixture was filtered to obtain a tetrazonium aqueous solution.

2-hydroxy-3-α, α, as a coupling component
α, α′, α′, α′-hexafluoro-3′, 5′
- for xyl) naphthoic acid amide (t:d! points 235-2
36.5℃) 12 S! 'l O,03mole),
Triethanolamine 15 as an organic amine! i'(0
, 1 mole) of DMFooOd; Dissolve L% 0-5
Cooled to ℃. Next, the diazonium-filled solution described above was added dropwise into the Kuffler solution, and the resulting purple paste-like liquid was maintained at a temperature of 0 to 10 DEG C. and allowed to entrain for an additional 3 hours.

The formed precipitate is filtered, thoroughly washed with acetone and then water, and finally washed again with acetone. After drying, the precipitate is dried.
A black-blue powder was obtained. The melting point was 350°C or higher.

Other azo compounds of the present invention can also be obtained according to the above synthesis examples.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more azo compounds represented by the general formula (1). Various types of photosensitive layers are well known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may include any of them. Usually, the photosensitive layer is of the type exemplified below.

■ A photosensitive layer made of an azo compound ■ A photosensitive layer in which an azo compound is dispersed in a binder ■ A photosensitive layer in which an azo compound is dispersed in a well-known charge transfer substance The azo compound represented by the above general formula generates charge carriers with extremely high efficiency when it absorbs light. Although the generated carriers can be transferred using an azo compound as a medium, it is preferable to transfer them using a well-known charged f8 animal w as a medium. From this point of view, photosensitive layers in the form (1) and (2) are 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 G of the photoreceptor of the present invention, and a mixture of substances having the same type of function can be used. Or is it a mixture of things with different functions?
can also be used. Examples of substances having electron transfer include electron-withdrawing compounds having electron-withdrawing groups such as nitro groups, cyano groups, and ester groups; examples of these include:
2.4.7-Dolinitrofluorenone, 2.4.5.7
- Nitrated fluorenone such as titranitrophylolenon, or compounds such as tetracyano, quinodimethane, tetracyanoethylene, 2.4.5.7-titrani I. loxanthone, 2.4.8-trinidrothioxanthone, and these electron Examples include completely polymerized absorbent compounds.

Further, examples of the hole transport medium include electron-donating organic photoconductive compounds as follows.

hydrazones C, Hs C,H.

CM.

Pyrazone 1) (9)' t diaryl alkanes -C3H7 -C3H7 C8H7 -C3H7 2H5 -C3H7 H3 nC@HI3 Alkylene diamines Dibenzylanilines Triphenylamines Diphenylbenzylamines 1j Aryl alkanes CH.

CR3 Oxadiazoles include anthracene, oxazole, and thiazole (Ct H%)2N. Other polymeric compounds include 1) + N-vinylcarbazole, halogenated 1) N-vinylcarbazole, polyvinylpyrene,
Polyvinylanthracene, polyvinylacridine 1.
Polyglycidylcarbazole, polyvinylacenaphthylene, ethylcarbasol-formaldehyde resin, etc. can also be used.

The carrier transfer substances are not limited to those described herein, and one or more carrier transfer substances may be used in the side piece.

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

For example, an electrophotographic photoreceptor having a photosensitive layer of type (1) above is prepared by dissolving or dispersing the azo compound represented by the general formula (1) in an appropriate medium, and applying a coating solution to the conductive support. It can be manufactured by coating and drying to form a photosensitive layer having a thickness of usually several μm to several + μm.

Media for preparing the coating solution include basic solvents that dissolve bisazo compounds such as butylamine and ethylenediamine, ethers such as tetrahydrofuran and 1,4-dioxane, ketones such as dimethyl ethyl ketone and cyclohexanone, and aromatic substances such as toluene and xylene. Group hydrocarbon: N
, N-dimethylformamide, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, etc.; alcohols such as methanol, ethanol, impropatol; esters such as ethyl acetate, methyl acetate, methyl cellosolve acetate; dichloroethane; Examples include media that completely disperse the azo compound, such as chlorinated hydrocarbons such as chloroform.

When using a medium in which the azo compound is completely dispersed, it is necessary to micronize the azo compound to a particle size of 5 μm or less, preferably 3 μm or less, and optimally 1 μm or less.

Further, 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 plastic 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.

By dissolving a binder in the coating liquid used to form the photosensitive layer of the type (2) above, it is possible to produce an electrophotographic photoreceptor having the photosensitive layer of the type (2) above.

In this case, it is preferable that the medium of the coating liquid completely 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 bo-17ol resin.

The amount of binder used is usually 0.1 to 0.1 to the amount of the azo compound.
The range is 5 times the weight.

When forming the entire photosensitive layer of this type, it is preferable that the bisazo compound be present in the binder in the form of fine particles, for example, with a particle size of 3 μm or less, particularly 1 μm or less.

Similarly, by dissolving a charge transfer medium in the coating liquid used to form all of the photosensitive layers of type (1) above, it is possible to produce an electrophotographic photoreceptor having all of the photosensitive layers of type (2). 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 amount of the binder used is usually 3 to 500 times the weight of the haazo compound, and the amount of the charge transfer medium used is usually 0.2 to 1.5 times the weight of the binder, preferably 0.3 to 500 times the weight of the binder. The range is 1.2 times the weight. In the case of charge transfer media that can themselves be used as binders,
Azo compound [Usually used 5 to 10 times by weight.

Is this type of photosensitive layer also a bisazo compound like the photosensitive layer of type ① above? Preferably, it is present in the charge transport medium and binder in particulate form.

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 layer, the electron Photographic photoreceptors can be manufactured.

In this case, the photosensitive layers of types (1) to (4) above serve as charge generation layers. The charge transport layer does not necessarily need to be provided on top of the charge generation layer, but may be provided between the charge generation layer and the conductive support. The former is preferable from the viewpoint of L or L1 durability.

The formation of the charge transfer layer is carried out in the same manner as the formation of the entire photosensitive layer in step (2) above. That is, the coating solution used for forming the entire photosensitive layer described in (1) above except the azo compound may be used as the coating solution.

Typically the charge generating layer is 5 to 50 microns thick.

Of course, from zero! The photosensitive layer of the electrophotographic photoreceptor may contain a known sensitizer.

Suitable sensitizing types include Lewis acids and dyes that form charge transport media with organic photoconductive materials.

Examples of Lewis acids include quinones such as chloranil, 2,3-cyclo-L4-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 a3'55'-tetranitrobenzophenone, acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, cyano compounds such as tetracyanoethyln, terephthalmalonitrile, and 4-nitrobenzalmalonnitrile =3-benzal7thalide, 3-(a-cyano p
-nitrobenzal)phthalide, 3-(a-cyano-p-
Examples include electron-withdrawing compounds such as 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, and cyanine dyes, pyrylium salts, chiapi 1) um salts, benzobium + 1 + 1 um, etc. Examples include salt.

In addition, it may contain inorganic photoconductive fine particles such as G-4 selenium and selenium-arsenic alloy, and organic photoconductive pigments such as copper, phthalocyanine pigments, and perylene pigments. 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, phthalate esters, phosphate esters,
Examples include epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and aromatic compounds such as methylnaphthalene.

It goes without saying that it may also have an adhesive layer, a ridge layer, and a transparent insulating layer, if necessary.

The photoreceptor using the azo compound of the present invention has high sensitivity and good color sensitivity, and when used repeatedly, there is little variation in sensitivity and chargeability, little optical fatigue, and extremely high durability. It is.

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

■) Examples Next, the present invention will be explained in more detail using examples, but what is the gist of the present invention? The invention is not limited to the following examples as long as it does not exceed this.

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: anhydrous maleic vinegar copolymer (S-LEC MF-
10) A 0.05 μm thick intermediate layer consisting of 2? of exemplary compound A1 was completely formed. and polyarylate resin (Unitika vu
-100)2? An azo compound dispersion obtained by dispersing in a paint conditioner for about 1 hour in addition to 'tL2-diglolethane 100- was coated and dried on the intermediate layer so that the film thickness after drying was 0.5μ. Form a carrier generation layer, and further E carrier movement? I'("f
N,N-dibenzylaminobenzaldehyde-Ll-diphenylhydrazone 5? Boria arylate tree 1) 17?
At the same time, a solution dissolved in 50 ml of L2-dichloroethane was coated and dried so that the film thickness after drying was 12 μm to form a carrier transport layer, thereby producing an electrophotographic photoreceptor of the present invention. After storing this photoreceptor at a room temperature of 30°C in a dark place for -week, the electrophotographic photoreceptor was tested using an electrostatic paper tester 1'-3P-42.
8J (newly manufactured by Kawaguchi Electric) was installed, and the following characteristic tests were conducted.

That is, a voltage of -6 KV is applied to the charger and the entire photosensitive layer is charged by corona discharge for 5 seconds, and the potential at that time Vot-V>
Then, with the illumination intensity on the surface G of the photosensitive layer being 301ux, the exposure amount E-j(
lux・sec)k was calculated.

Also, the surface potential after exposure with an exposure amount of 30 lux·sec, that is, the residual potential E. (-V)k was calculated. Similar measurements were repeated a total of 500 times. In addition, a 300 l tungsten lamp was used as a light source to eliminate residual potential.
After 7 more exposures for 0.3 seconds at UX, the residual potential was completely 1! I made it to.

The results are shown in Table 1.

Table 1 Examples 2 to 4 Each exemplified compound 259't as a carrier generating substance
A total of three types of electrophotographic photoreceptors of the present invention were prepared in the same manner as in Example 1, except that the following were used, and the same characteristic tests were conducted on each of the two.

Also shown are the results of a similar test using the following azo compound as a comparative compound.

Example 5 On the outer surface of a 60 wm diameter drum made of aluminum, a 0.04 μ thick layer of vinyl chloride: vinyl acetate (87:13) copolymer (tJc I C9VYHH) was applied.
In addition to 400WLl of 4yt''L2-dichloroethane of Exemplary Compound 1), paint cond.
The entire dispersion obtained by dispersing for about 3 hours using a
A carrier generating layer was formed on the intermediate layer by coating and drying so that the film thickness after drying was 0.5 μm. A carrier transfer material N, N-diallylaminobenzaldehyde-1-7enyl-1-methylhydrazone io, s+t-po1) carbonate resin (manufactured in large quantities by Panlite L-t25o) iz5' is formed on this carrier generation layer. 1.
A solution dissolved in 100 mJ of 2-dichloroethane was coated and dried to a film thickness of 15 .mu.m 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 attached to a commercially available cartridge-type electrophotographic copying machine modified by our company and a copy image was formed, a clear visible image with high contrast (14% fidelity) was obtained. .

My father repeated the copying process 1,000 times, but by the end he was able to obtain a visible image equivalent to the first time.

Furthermore, when the spectral sensitivity at 670 nm and 680 nm was measured using a monochrome meter, the energy required to halve the potential was approximately 3.5 erg/d for both wavelengths, which is a very high photoreceptor. LED)
It was found that the photoreceptor was durable enough for practical use even when used in the photoreceptor.

Example 6 A styrene: methyl methacrylate: methacrylic acid copolymer (styrene: methyl methacrylate = 2:1 weight ratio, acid value 185), exemplified compound 13, and trinitrofluorenone were placed on a grained Al plate. tt, s:t:
A solution prepared by dissolving (resin component, trinitro-70-lenone) and dispersing (azo compound) all in dioxane was applied and dried to prepare a single-layer type photoreceptor having a film thickness of 6 μm.

The photoreceptor of the present invention thus prepared was subjected to an electrophotographic property test using the electrostatic paper testing apparatus described above.

Applied "di pressure + 6KV Vo = 420 (+V) E÷ = 4.0 (lux
・Seconds). First, this photoreceptor is visualized with a developer (toner), and then an alkaline processing solution (e.g., 3% triethanolamine, 10% ammonium carbonate, and 20% polyethylene glycol with an average molecular weight of 190 to 210)
When treated, the toner-free areas were easily eluted, and 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 lamp)
The optimum exposure amount was 30 lux·sec, and the printing original plate was created by direct plate making without using any base material.

Effects of the Invention The electrophotographic photoreceptor of the present invention has high sensitivity, low residual potential, and excellent durability with little change in characteristics even after repeated use. They can be combined.

Claims (1)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing an azo compound represented by the following general formula (1) on a conductive support. General formula (1) ▲ Numerical formulas, chemical formulas, tables, etc. A group of atoms necessary to form a carbocyclic aromatic ring, a substituted or unsubstituted heterocyclic aromatic ring, or an unsaturated monocyclic hydrocarbon ring.)