JPH03192367A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body which has the excellent red color reproducibility of an original, a high sensitivity and small residual potential and has an excellent preexposing characteristic and repetitive use characteristic by providing a photosensitive layer contg. a specific azo pigment on a conductive base. CONSTITUTION:The azo pigment expressed by general formula [I] is used as the photoconductive material to constitute the photosensitive layer of the electrophotographic sensitive body. Only the excellent carrier generatability of this azo pigment is utilized and this pigment is used as the carrier generating material of the so-called separated function type electrophotographic sensitive body which executes the generation and transfer of the carrier by respectively separate materials. As a result, the electrophotographic sensitive body which has excellent film properties and the excellent electrophotographic characteristics, such as charge holding power, sensitivity and residual potential, is less fatigued and deteriorated even after repetitive use, is not changed in characteristics by heat or light and can exhibit the stable characteristics is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field 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 that has high sensitivity and is suitable for repeated use.

(B) Prior Art and its Problems Conventionally, electrophotographic photoreceptors having photosensitive layers containing inorganic photoconductors such as selenium, zinc oxide, and cadmium sulfide as main components 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 limitations in manufacturing and handling due to their toxicity. .

On the other hand, an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a 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 (known, this and 2.4
．． Electrophotographic photoreceptors having a photosensitive layer mainly composed of a charge transfer complex formed with a Lewis acid such as 7-4linitro-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 movement function are assigned to separate substances, each material has a wide selection 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, an electrophotographic photoreceptor has been put into practical use that has a photosensitive layer that combines a carrier generation layer made of amorphous selenium and a carrier transfer layer mainly composed of poly-N-vinylcarbazole.

However, the carrier generation layer made of amorphous selenium has the disadvantage of poor durability.

In addition, various proposals have been made to use organic dyes and pigments as carrier-generating substances. 52-424
Publication No. 1, Japanese Unexamined Patent Publication No. 1983-46558, Special Publication No. 1983
-11945 publication etc. are already publicly known.

However, these azo pigments are not necessarily satisfactory in characteristics such as sensitivity, residual potential, and stability upon repeated use.

Incidentally, in addition to the above-mentioned characteristics, the photoreceptor used in an electronic copying machine that uses a halogen lamp or the like as a light source has a maximum spectral sensitivity in the range of about 500 nm to about 600 nm in order to reproduce the red color of the original. , it is desirable that long wavelengths be cut off as sharply as possible.

However, among azo pigments having such spectral sensitivity characteristics, electrophotographic photoreceptors having a photosensitive layer containing azo pigments have high sensitivity, low residual potential, and excellent pre-exposure characteristics and repeatability characteristics. The reality is that it is hardly known.

(C) Purpose of the Invention The purpose of the present invention is to provide excellent red reproducibility of originals, high sensitivity,
An object of the present invention is to provide an electrophotographic photoreceptor having a low residual potential and excellent pre-exposure characteristics and repeated use characteristics.

CD) Structure of the Invention The above-mentioned object of the present invention is to provide the following general formula C on a conductive support.
This was achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an a5zo pigment represented by I).

General formula [1) % formula % [wherein R1 and R2 represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a substituent thereof,
R3 represents a hydrogen atom, a halogen atom or a cyano group.

In addition, Cp represents H R4R5 or -C-0-R'', and X represents an aromatic ring or a heterocyclic ring (these rings are ), R4 and R5 represent an alkyl group, a phenyl group, or a substituted product thereof, and R6 represents a hydrogen atom, an alkyl group, a carbamoyl group, or a carboxyl group. , an alkoxycarbonyl group, an aryloxycarbonyl group, or a substituted or unsubstituted amino group, RT, R8 and R'' represent an alkyl group, an aromatic ring group, a heterocyclic group or a substituent thereof, and R9 to RI 8 represents a hydrogen atom, an alkyl group, an aromatic ring group, a heterocyclic group, or a substituted product thereof.

However, R10 and R", R12 and R", RI4 and RIll
are never hydrogen atoms at the same time.

W represents a divalent aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic divalent group containing a nitrogen atom in the ring. That is, in the present invention, by using the azo pigment represented by the general formula CI) as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, the azo pigment of the present invention has excellent chiaria generation. By using this as a carrier-generating material in so-called function-separated electrophotographic photoreceptors, in which carrier generation and transfer are performed using separate substances, the film has excellent physical properties, and has excellent charge retention, sensitivity, and residual properties. An electrophotographic photoreceptor that has excellent electrophotographic properties such as electric potential, has little fatigue deterioration even when used repeatedly, and does not change the above-mentioned properties even when exposed to heat or light, and can exhibit stable properties. can be created.

Specific examples of azo pigments useful in the present invention represented by the above-mentioned formula include those having the following structural formula.

(1) (A) (R' = R" = R3 = H) N = N-C
p (blank below) (I) (B) (R1=R2=H, R”=CH) N=N-
Cp [1) (C) (R' = R" = H, R" = 2-Cj
)N=N-Cp (1) (D) (R" = R' = H, R' = 2'
-Ct )N=N-Cp (1) (E) (R'-2' 0CRs, R' =
3 CH3, R" = H) N=N-CP (1) (F) (R' = 2' -CO2, R" =
3-OCHs, R"=CN) (1) The azo pigment represented by the general formula [I] is represented by the following formula 3 1 NH.

(However, R1 and R3 are the same as in general formula (1)) 2
azotizing the amino compound of the same value by a conventional method, and then coupling the corresponding coupler in the presence of an alkali, or
Alternatively, after first isolating the diazonium salt of the divalent amino compound mentioned above in the form of a borofluoride salt or a zinc chloride double salt, a suitable solvent (for example, N,N-dimethylformamide,
dimethyl sulfoxide, ethanol, dioxane)
Among them, it can be easily synthesized by carrying out a coupling reaction with a coupler in the presence of an organic or inorganic alkali.

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

Synthesis Example (Synthesis of Exemplified Compound 4) 1-(4-nitrophenyl)imidazole 5 obtained by reacting imidazole with p-fluoronitroaniline
．． 01g was reacted with 27ml of 37% formaldehyde aqueous solution in a sealed tube at 140°C to obtain 4.64g of crystals of (a).

Melting point 199-200°, yield 80%.

(a) 2.0g and 0.9g of potassium dichromate in 40m
After heating at 80°C for 1.5 hours in acetic acid of 150 m
1. Pour into ice water, collect the obtained crystals by filtration, and purify by column chromatography to obtain 1.29 g of crystals (b). Melting point 166.2-166°8°, yield 65%.

(C) 1-(4-nitrophenyl-2-(2-(4'
-nitrostyryl)] Synthesis of imidazole (b) 3.7
5g and diethyl 4-nitrobenzylphosphonate5.
4 g in the presence of 2.5 g of potassium t-butoxide
After stirring in mlN,N-dimethylformamide for 5 hours, it was poured into 400ml ice water, and the precipitated crystals were washed with water, then with methanol, and then dried to give crystals of (C) 3.9
get g. Melting point 251.5-252.5°, yield 67%
.

15 g of reduced iron was stirred and suspended in 15 ml of dioxane and 15 ml of water at 90°C, 3 ml of acetic acid was added, and 3.36 g of (C) was gradually added to cause a reaction, and then filtered while hot. Concentrate the filtrate. This is 200
After extraction with 1 ml of ethyl acetate, the extract is washed with a saturated aqueous sodium bicarbonate solution and then with brine, dried over magnesium sulfate, and the solvent is distilled off to obtain 2.76 g of crystals (d). Melting point 198-199°, yield 99%.

(e) Synthesis of Exemplified Compound 4 (d) 276 mg was dissolved in 20 ml of DMF, 3 ml of 2N hydrochloric acid was added, and while stirring, a solution of 145 μm of sodium nitrite dissolved in 1 ml of water was added dropwise at -10°C.
A tetrazonium salt is obtained by reacting for several minutes.

The tetrazonium salt solution thus obtained was dropped into a cooled and stirred solution of 595 μl of 2-hydroxy-3-naphthoic acid θ-chloroanilide and 1.6 ml of triethanolamine dissolved in 20 ml of DMF. After stirring for about 2 hours, the formed crystals were collected by filtration and washed with DMF, water, and acetone to obtain the desired crystals of Exemplary Compound 4 653■
I got it.

Melting point 330° or higher, yield 73%.

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

The electrophotographic photoreceptor of the present invention contains the bisazo pigment in the photosensitive layer, and the bisazo pigment can be used in various embodiments. For example, use a bisazo pigment as a binder (
It can be used as a photoconductive layer by dispersing it in a binder) and coating this dispersion on a conductive support. Alternatively, a photosensitive layer can be formed by dispersing a bisazo pigment as a charge generating agent in a charge transporting material and coating this dispersed mixture on a conductive support.

In yet another embodiment, it can be used as a laminated photoreceptor in which a charge generation layer containing a bisazo pigment as a charge generation agent is provided on a conductive support, and a charge transport layer is provided thereon. In this case, the charge generation layer may be formed by depositing an azo pigment on the conductive support, or by dispersing the azo pigment in a binder resin and coating the dispersion. .

Examples of the binder resin used for dispersing the charge generating agent in the above embodiment include polyester resin, acrylic resin, styrene resin, silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, and styrene-butadiene copolymer. Coalescence, polyvinyl acetal resin, diallyl phthalate resin, polysulfone resin, polycarbonate resin, acetic acid-bicrotonic acid copolymer resin, polyarylate resin, butyral resin, styrene-maleic anhydride copolymer resin, rosin-phenol modified resin, casein etc.,
These can be used alone or in combination as a copolymer. The amount of these binders used is 0.00% by weight relative to the bisazo pigment. It is used at a ratio of 1 to 5 times, but preferably 0. A range of 2 to 3 times is suitable.

Further, as the charge transport material forming the charge transport layer, a known conductive compound can be used.

For example, hole transporting substances include polyvinylcarbazole, phenanthrene, N-ethylcarbazole, 2,5
-diphenyl-1,3,4-oxadiazole, 2,5
-bis(4-diethylaminophenyl')-1,3,4
-Oxadiazole, 4.4'-bis(diethylamino)-2,2'dimethyltriphenylmethane, 2.4.5
-) Lis(p-diethylaminophenyl)oxazole, 2.5-bis(p-diethylaminophenyl) = 1.
3.4-triazole, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline, p-diethylaminobenzaldehyde-diphenylhydrazone, N-ethyl-carbazole-3-carbo Examples include xaldehyde-diphenylhydrazine, and examples of electron transport substances include 2-nitro-9-fluorenone, 2.7-sinitro-9-fluorenone, 2.4.7-dolinitro-9-fluorenone,
Examples include 2-nitrobenzothiophenone, dinitroanthracene, dinitroacridine, dinitroanthraquinone, and the like.

These charge transport substances can be used by being dispersed or dissolved in a binder resin, and the resins mentioned above can be used as the binder resin. The amount of the binder used is 0.1 to 10 times the weight of the charge transport material, preferably 0.2 to 5 times the amount by weight.

Examples of the conductive support used for producing the photoreceptor of the present invention include a metal plate, conductive paper, conductive plastic film, metallized film, metal cylinder, and plastic cylinder treated with metallization or metal foil. and so on. Examples of solvents used for coating these supports by dispersing or dissolving azo pigments and charge transport substances together with binders include toluene, xylene, monochlorobenzene, chloroform, dichloroethane, trichloroethylene, methylene chloride, Dioxane, tetrahydrofuran, ethyl acetate, butyl acetate, methyl cellosolve,
Methyl cellosolve acetate, cyclohexanone, methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, ethyl alcohol, propyl alcohol,
Butyl alcohol etc.

(E) Examples Next, examples of the present invention will be shown.

Example 1 Exemplary Pigment 4 according to the present invention and the following pigments R-1, R-2, R-3 and R-4 as -1 -2 -3 -4 were each mixed with 1 part by weight of a polyarylate resin. (Unitika U-1
00) was mixed with 100 parts by weight of dichloroethane and dispersed together with glass beads for 2 hours using a paint conditioner device. The pigment dispersion thus obtained was coated with a wire bar on an aluminum support for PS plates (anodized, manufactured by Agfa), and the film thickness was 0.
A charge generating layer of 2-0.3 microns was provided.

Next, a coating solution prepared by dissolving 1 part by weight of p-dibenzylaminobenzaldehyde-diphenylhydrazone as a charge transport material and 1 part by weight of polyarylate resin in 10 parts by weight of dichloroethane is applied onto the charge generation layer using a wire bar. In this way, a laminated photoreceptor having a charge transport layer with a thickness of 15 microns was produced.

Regarding this photoreceptor, an electrostatic recording tester (manufactured by Kawaguchi Electric, 5P-
428), the following characteristic tests were conducted.

That is, a voltage of -6 KV is applied to the charger to charge the photosensitive layer by corona discharge for 5 seconds, and the potential at that time Vo (V
), find the potential Vd (V) after standing for 10 seconds, DD=
Vd/VOX100 (%) was measured. Also, the exposure amount E1/2 (LUX seconds) required to attenuate the surface potential of the photosensitive layer by 1/2 by irradiating light from a halogen lamp with the illumination intensity on the photosensitive layer being 30 LUX.
I asked for Next, this photoreceptor was exposed to the light of a fluorescent lamp with an illuminance of 5000 LUX for 5 minutes, and after being left in a dark place for 30 seconds,
Conducting a characteristic test similar to the above, the charging potential Vo (V)
, El/2 (LUX sec> DD (%)) were determined. The results are shown in Table 1.

The upper row of Table 1 shows the initial characteristics, and the lower row shows the characteristics after light irradiation.

(The following is a blank space) From the results in Table 1, it can be seen that the photoreceptor using Azo Pigment 4 of the present invention has very good charging potential vO1 sensitivity and pre-exposure characteristics.

Next, the surface potential after exposing these photoreceptors at an exposure amount of 50 LUX·sec, that is, the residual potential E. (V)
I asked for Similar measurements were repeated 500 times.

In addition, a tungsten lamp was used as a light source to remove residual potential, and the light source was 300 LUX and 0. Further irradiation exposure was performed for 3 seconds to completely reduce the residual potential to 0. The results are shown in Table 2.

(The following is a blank space) From the results in Table 2, it can be seen that the photoreceptor using Azo Pigment 4 of the present invention has excellent repeated use characteristics.

Example 2 Exemplary pigments 11.14 and 17 of the present invention as described above,
For comparison, 2 parts by weight of each of the following pigments R-5, R-6 and R-7 (hereinafter referred to as margins), 1 part by weight of polycarbonate resin (Kijin Kasei Panlite-1250) and 1 part by weight of dichloroethane were added to 50 parts by weight of dichloroethane. and dispersed with paint conditioner for 2 hours. This dispersion was applied onto the surface of an aluminum cylinder having an outer diameter of 60 m by a cylindrical pull-up coating method. The film thickness is approximately 0.
It was 5 microns.

On this charge generation layer, 1 part by weight of 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 2 parts by weight of polyester resin (Vylon-200) and 25 parts by weight of dichloroethane were added. A charge transport layer having a thickness of 15 microns was formed by applying the dissolved solution to produce a cylindrical photoreceptor. The charged potential Vo (V) and general sensitivity El/2 (LUX -5et) of this photoreceptor were determined in the same manner as in Example 1, and then monochromatic light with a wavelength of 600 nm (photosensitive Surface illuminance on the body 1μW/12
f), the time (seconds) required for the surface potential to decrease to 1/2 of the initial potential was measured, and the half-reduction exposure amount (El
/2 < 600 >) was determined as the spectral sensitivity at 600 nm. The results are shown in Table 3.

From the above results, it was confirmed that all of the photoreceptors of the present invention have excellent characteristics not only in general sensitivity but also in red sensitivity, as compared to the characteristics of comparative photoreceptors.

(The following is a blank space) Example 3 Exemplary pigment 5.29.53.77.1 according to the present invention described above
As a comparison with 01.125 and 149, the following pigment R-
8 and R-9 (hereinafter blank) -8 R-9 (hereinafter blank) 1 part by weight each, polyarylate resin (Unitika U-1
00) was mixed with 100 parts by weight of dichloroethane and dispersed in the same manner as in Example (1) above to obtain a coating dispersion. An aluminum support for PS plates (anodized, manufactured by Agfa) was coated in the same manner as the support, and a charge generation layer of 0.2 to 0.3 microns in thickness was provided on each layer. A coating solution prepared by dissolving 1 part by weight of p-benzylaminobenzaldehyde-diphenylhydrazone and 1 part by weight of polyarylate resin in 10 parts by weight of dichloroethane as a transport material was similarly applied onto the charge generation layer to form a charge film with a thickness of 15 microns. A laminated photoreceptor with a transport layer was created. The white light sensitivity and spectral sensitivity at 600 nm of this photoreceptor were measured in the same manner as in Example 2. The results are shown in Table 4.

As is clear from the above, the method of the present invention provides high sensitivity,
It is possible to obtain an electrophotographic photoreceptor having a low residual potential and excellent pre-exposure characteristics and repeated use characteristics.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula [I] on a conductive support. General formula [I] ▲ Numerical formulas, chemical formulas, tables, etc. represents a hydrogen atom, a halogen atom or a cyano group. Also, Cp has ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲There are mathematical formulas, chemical formulas, tables, etc.▼,▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents represents an atomic group necessary to form an aromatic ring or a heterocycle (these rings may be substituted or unsubstituted); There are tables, etc. ▼ represents, R^4 and R^5 represent an alkyl group, phenyl group, or a substituted product thereof, and R^6 represents a hydrogen atom, an alkyl group,
Represents a carbamoyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, or substituted or unsubstituted amino group, R^7, R^8 and R^1
^6 represents an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof, and R^9 to R^1^5 represent a hydrogen atom, an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof represent the body. However, R^1^0 and R^1^1, R^1^2 and R^1^
3. R^1^4 and R^1^5 are never hydrogen atoms at the same time. W represents a divalent aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic divalent group containing a nitrogen atom in the ring. ]