JPH0476557A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body high in sensitivity, low in residual potential, and superior in repeating use characteristics by using a specified azo pigment as a photoconductor for composing a photosensitive layer and as the carrier generating material of the photosensitive body. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains the azo pigment represented by formula I in which R<1> is H, halogen, or optionally substituted alkyl or alkoxy; each of R<2> and R<3> is H, alkyl, or aryl; Cp is a group of formula II - IV; X is an atomic group necessary to condense with the benzene ring having OH and Y in formula II and to form an aromatic or hetero ring; Y is a group of formula V or VI or the like; each of R<4> and R<5> is optionally substituted alkyl or phenyl; and each of R<12> - R<15> is H, alkyl, an aromatic, or heterocyclic group, or the like, thus permitting the obtained photosensitive body to attain the necessary characteristics by using the azo pigment having such a chemical structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a photosensitive layer containing a novel 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, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture and generally have superior thermal stability compared to selenium photoreceptors. It has the following advantages and has attracted much attention in recent years.

Such organic photoconductive compounds include poly-N-
Vinylcarbazole is well known, and 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-dolinitro and 9-fluorenone are not necessarily satisfactory in sensitivity and durability.

On the other hand, 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, have a wide range of materials to choose from, and have improved charging characteristics, sensitivity, and durability. 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. Showa 52-42
Publication No. 41, JP-A-54-46558, JP-A No. 5
6-11945 and the like are already known.

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

(C) Object of the Invention An object of the present invention is to provide an electrophotographic photoreceptor that has high sensitivity, low residual potential, and excellent pre-exposure characteristics and repeated use characteristics.

(D) Structure of the Invention The above object of the present invention is to apply the following general formula (
This was achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by I).

・General formula CI) Also, Cp is Of( [wherein, R1 is a hydrogen atom, a halogen atom, an alkyl group,
It represents an alkoxy group or a substituted product thereof, and R2 and R3 represent a hydrogen atom, an alkyl group or an aryl group.

X is an atom necessary to form an aromatic ring or a heterocycle (these rings may be substituted or unsubstituted) by condensation with the benzene ring in the above formula to which the hydroxy group and Y are bonded. 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, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a substituted or unsubstituted group. represents an amino group, R7, R8, and R16 represent an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof; R9 to R'' represent a hydrogen atom, an alkyl group, an aromatic ring group, a heterocyclic group, or represents their substituted forms.

However, R'' and R'', R12 and R13, and R'' and R'' are not 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 [I] as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, it is also possible to obtain an excellent carrier for the azo pigment of the present invention. By utilizing only the generation ability and using it as a carrier generation material in a so-called function-separated electrophotographic photoreceptor in which carrier generation and transfer are performed using separate substances, the film has excellent physical properties, such as charge retention, sensitivity, and An electrophotographic photosensitive material that has excellent electrophotographic properties such as residual potential, has little fatigue deterioration even after repeated use, and exhibits stable properties without changing the above-mentioned properties even when exposed to heat or light. It is possible to create a body.

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

(Margin below) (R1 = R2 =H) [I] (B) (R1 =CI.

= R3 =H) (R1 = R3 =H.

=06 CI] (D) (R+ =H.

= Rs = CH3 [I] (E) (R1 = C5 = R3 = CH3 The azo pigment represented by the above general formula CI) is prepared by diazotizing the diamine represented by the following general formula by a conventional method, and then converting the corresponding coupler into an alkali. or the diazonium salt of the aforementioned diamine in the form of a borofluoride salt or a zinc chloride double salt, etc., is isolated in the presence of a suitable solvent (e.g. 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 (Exemplary Compound 4) (a) Synthesis of 4-nitrohomophthalic anno
Heat at 0°C for 2 hours. After cooling, the precipitated crystals were collected by filtration, and 5
Disperse well in ml of acetic acid and wash, filter the crystals, and dry under reduced pressure and heat to obtain 6.56 g of crystals of (a).

Melting point: 139-141°C, yield: 71%.

Synthesis of

3 g of crystals of (a) were mixed with 2.9 g of 4-nitro-1,2-phenylenediamine, 7.2 ml of acetic acid and 4 ml of nitrobenzene.
Heat and stir at 135°C for 2 hours. After cooling, the precipitated crystals were collected by filtration, washed with 15 ml of nitrobenzene, and then twice with methanol, and the resulting crystals were dried by heating under reduced pressure to obtain 3.42 g of crystals (b).

Melting point: 320°C or higher, yield: 73%.

Synthesis of

3.5 ml of acetic acid is added in two portions to a mixture of 16 g of iron powder dispersed in 16 ml of dioxane and 16 ml of water and heated to 90° C. with vigorous stirring.

Further, while stirring at 90° C., 3°0 g of the crystal (b) dispersed in 50 ml of dioxane was added, followed by stirring and refluxing for about 30 minutes.

Insoluble matter is removed by filtration while hot, and the insoluble matter is further washed with hot dioxane. The filtrate and washing liquid are combined and the solvent is distilled off under reduced pressure, and the resulting residue is washed with water and then methanol, and then dried to obtain 1.12 g of crystals of (C).

Melting point: 320°C or higher, yield: 46%.

(d) Synthesis of Exemplary Compound 4 264 µ of crystals of (C) were dissolved in 20 ml of DMF, 3 ml of 2N hydrochloric acid was added, and a solution of 145 µ of sodium nitrite dissolved in 1 ml of water was added dropwise at -10°C while stirring. ,
React for 30 minutes to obtain a tetrazonium salt.

The tetrazonium salt solution thus obtained was mixed with 595 μl of 3hydroxy-2-(2'-chloro)naphthanilide.
and 0.9 ml of triethanolamine and 50 ml of DMF.
Drop the solution dissolved in water into the cooled and stirred medium, and add about 2
After stirring for an hour, the formed crystals were collected by filtration, DMF1 water,
Crystal 17 of the desired exemplary compound 4 after washing with acetone
I got 8 ■.

Melting point: 330°C or higher, yield: 20%.

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

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 to be used is 0.1 to 5 times the weight of the bisazo pigment, preferably 0.2 to 3 times.

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

For example, as the hole transport substance, 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-carboxaldehyde-diphenyl Examples include hydrazine, and examples of electron transport substances include 2-nitro9-
Fluorenone, 2,7-sinitro-9-fluorenone,
Examples include 2.4.7-dolinitro-9-fluorenone, 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 to coat these supports by dispersing or dissolving azo pigments and charge transport substances together with binders include toluene, xylene, monochlorobenzene, chloroform, dichloroethane, trichloroethylene, and methylene chloride. , dioxane, tetrahydrofuran, ethyl acetate, butyl acetate, methyl cellosolve,
Examples include methyl cellosolve acetate, cyclohexanone, methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, ethyl alcohol, propyl alcohol, and butyl alcohol.

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

Example 1 1 part by weight of each of the exemplary pigment 4 according to the present invention and the following pigments R-1, R-2, R-3 and R-4 (hereinafter referred to as blanks) for comparison, and 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 was applied onto the charge generation layer using a wire bar. A laminated photoreceptor having a charge transport layer with a thickness of 15 microns was prepared.

Regarding this photoreceptor, an electrostatic recording tester (Kawaguchi Electric type 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. In addition, the exposure amount El/2 (LUX sec) required to attenuate the surface potential of the photosensitive layer to 1/2 by irradiating light from a halogen lamp with the illumination intensity on the photosensitive layer being 30 LUX was determined. Ta. Next, this photoreceptor was exposed to the light of a fluorescent lamp with an illuminance of 5000 LUX for 5 minutes, left in a dark place for 30 seconds, and then subjected to the same characteristic test as above to determine the charging potential Vo (V
), El/2 (LUX · seconds) 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) Table 1 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 Vo, 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 E5° (V
) was sought. Similar measurements were repeated 500 times. Further, irradiation exposure was 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 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 11.15 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 (the following margins) and 1 part by weight of polycarbonate resin (Panlite-1250 manufactured by Ondai Kasei Co., Ltd.) were added to 50 parts by weight of dichloroethane. Dispersed with paint conditioner for 2 hours. This dispersion was applied onto the surface of an aluminum cylinder having an outer diameter of 60 mm 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 charging potential Vo (V) and the general sensitivity El/2 (LUX -5ec) were determined for this photoconductor in the same manner as in Example 1, and the initial charging potential after repeated charging exposure 10,000 times was determined. The difference ΔVo from the potential Vo was determined.

The results are shown in Table 3.

Table 3 (blank below) From the above results, it was confirmed that all of the photoreceptors of the present invention have higher general sensitivity and excellent characteristics for repeated use than those of the comparative photoreceptors.

Example 3 1 part by weight of each of the exemplary pigments 5, 29, 53, 77, and 101 according to the present invention, and the following pigment R8 for comparison, 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 used as a support and coated in the same manner as above to provide a charge generation layer with a thickness of 0.2 to 0.3 microns.

Next, a coating solution prepared by dissolving 1 part by weight of p-benzylaminobenzaldehyde-diphenylhydrazone and 1 part by weight of polyarylate resin as a charge transport material in 10 parts by weight of dichloroethane was similarly applied onto the charge generation layer to obtain a film thickness of 15 microns. A laminated photoreceptor with a charge transport layer was fabricated. The white light sensitivity of this photoreceptor was measured in the same manner as in Example 2, and the difference △Vo between the charging potential and Vo after 10,000 repetitions of charging and exposure, and the residual potential △Vr after static elimination were measured. It was measured. The results are shown in Table 4.

(Hereinafter in the margin) (Hereinafter in the margin) From the above results, the photoreceptor of the present invention has excellent characteristics such as higher general sensitivity, better repeatability, and lower residual potential than the characteristics of the comparative photoreceptor. It was confirmed that it has.

(F) Effects of the invention As is clear from the above, the method of the present invention achieves 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] 1. 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] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R^1 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a substituent thereof,
and R^3 represents a hydrogen atom, an alkyl group or an aryl 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 an atomic group necessary to condense to form an aromatic ring or a heterocycle (these rings may be substituted or unsubstituted), and Y is a ▲ mathematical formula, chemical formula, table, etc. ▼, ▲ mathematical formula, Chemical formulas, tables, etc. are available▼ or ▲Mathematical formulas, chemical formulas, tables, etc. are available▼, R^4 and R^5 represent an alkyl group, phenyl group, or a substituent thereof, and R^6 is a hydrogen atom, an alkyl group. basis,
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. ]