JPH0375663A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To reduce residual potential and to enhance preexposure characteristics and repeated use enduring characteristics by forming a photosensitive layer containing a specified azo pigment on a conductive substrate. CONSTITUTION:The photosensitive layer formed on the conductive substrate contains the azo pigment represented by formula I in which each of R<1> and R<2> is H, alkyl, or the like; R<3> is H, halogen, or the like; Cp is a group of formula II or III or the like; R4 is alkyl, phenyl, or the like; R5 is H, carbamoyl, or the like; and R6 is alkyl, aryl, or the like, thus permitting the red color reproduction performance of an original to be enhanced, residual potential to be reduced, and repeated uses enduring characteristics and the like to be elevated.

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.

CB) 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 are toxic and have restrictions on manufacturing and handling. was there.

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. !
It has many advantages over selenium photoreceptors, such as superior thermal stability, and has recently been attracting a lot of attention.

Such organic photoconductive compounds include poly-N-
Vinyl carbazole is well known, and this and 2.4
．． 7-) Electrophotographic photoreceptors having a photosensitive layer mainly composed of a charge transfer complex formed with a Lewis acid such as dinitro-9-fluorenone are not necessarily satisfactory in terms of 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 different charging characteristics and sensitivity.

It has the advantage that an electrophotographic photoreceptor having arbitrary electrophotographic properties such as durability 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 terms of 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 paper 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 the long wavelength side be cut off as sharply as possible.

However, among azo pigments with such spectral sensitivity characteristics, electrophotographic photosensitive materials having a photosensitive layer containing an azo pigment have high sensitivity, low residual potential, and excellent pre-exposure characteristics and repeated use characteristics. The reality is that very little is known about the body.

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

(D) Structure of the Invention The above-mentioned object of the present invention is to form the following pattern holes on a conductive support.
This was achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing the Azopho family represented by I].

General formula [I] [In the formula, R1 and R2 represent a hydrogen atom,...a rogen atom, an alkyl group, an alkoxy group, or a tm form thereof, and R represents a hydrogen atom, a halogen atom, or a cyano group.

In addition, Cp and X are condensed with the benzene ring in the above formula to which the hydroxy group and Y are bonded to form an aromatic ring or a polychord ring (these rings may be substituted or unsubstituted). Represents the atomic group necessary to do so, and represents 1 or -〇-0-R.

R4 represents an alkyl group, a phenyl group, or a substituted product thereof; R5 represents a hydrogen atom, an alkyl group, a carbamoyl group, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a substituted or unsubstituted amino group; , R6 represents an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof; R7 and R8 represent a hydrogen atom, an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof. However, R7 and R
8 is never a hydrogen atom at the same time. 0 1 Moreover, when Y is -〇-0-R', 88 is never a hydrogen atom.

W represents a divalent group of an aromatic hydrocarbon or a substituted or unsubstituted bivalent group of a polycyclic ring containing a nitrogen atom in the ring. ] That is, according to the present invention, by using the azo pigment represented by the above-mentioned symbol [113] as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, the advantages of the azo pigment of the present invention can be improved. It is suitable for use as a carrier-generating material in so-called gutter-separated electrophotographic photoreceptors, in which the generation and transfer of gold carriers are performed using separate substances, by utilizing only the carrier-generating ability of gold carriers. It has excellent electrophotographic properties such as holding power, sensitivity, and residual potential, and exhibits stable properties with little fatigue deterioration even after repeated use, and the above properties do not change even when exposed to heat or light. It is possible to create an electrophotographic photoreceptor that can be used.

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

[I]

(A) (R'=R12B'=H)CI) CB) (R'=R2=H.

R"==:CN) [!] (C) (R'=R'=H1 R2=2 Ct) [I] CD) (R"=R'=H1 R'=2'-Ct) [■] (E) (R' = 2'-0CRs, R2 = 3-CHs, R'
=H) [I] (F) (R'= 2'-CR2, R2= 3-OCH3, R5
=ON)CI) (G) (R'=2'-CH2C6H5, R2=3-OCH2C
6Hs, R'=Ct) The azo pigment represented by -Momonana [I] is obtained by adding a divalent amino form represented by the following general R2 (however, R1 to R1' are the same as the general formula [1)) by a conventional method. azotization, and then coupling the corresponding coupler in the presence of an alkali, or the diazonium salt of the divalent amino compound described above is isolated in the form of a boroheptafluoride salt or a zinc chloride double salt, etc. After that, it can be easily synthesized by coupling reaction with a coupler in a suitable solvent (e.g., N,N-dimethylformamide, dimethylsulfoxide, ethanol, dioxane) 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 described.

Synthesis Example (Exemplary Compound 6) 1-(p-nitrophenyl)virol-2-carboxaldehyde 10t obtained by the reaction of furfural and p-nitroaniline and diethyl-p-nitrobenzylphos 7one) 14.7f 1-(p-nitrophenyl)-2-(p-nitrosteryl)pyrrole (Fm point 194-196°) 12. Reacted with 6.6t of potassium-1-butoxide in total 100m DMF.
Get 9t.

The dinitro form of virol thus obtained 12. Of is reduced with iron powder and glacial acetic acid to obtain the diamino form of pyrrole (l
i1! lI point 158-16X°) 8.1? (Structural formula below) The above diamino compound 275■ was dissolved in 20 Ill of DMF, 2N hydrochloric acid 4- was added, and the mixture was stirred at -10°C.
A solution of 145 ml of sodium nitrite dissolved in 1 d of water was added dropwise to the solution, and the mixture was allowed to react for 30 minutes to obtain a tetrazonium salt.

The thus obtained tetrazonium salt solution t-2-hydroxy-3-naphthoic acid O-methylanilide 387η and triethanolamine 1.6- dissolved in DMF 20- was cooled and dropped into the stirring medium. After stirring for about 2 hours, the produced crystal eF was collected and washed with DMF, water, and acetone to obtain the desired crystal 433q of Exemplary Compound 6.

Melting point 330° or higher, yield 63%.

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 the bisazo pigment f as a charge generating agent in a TL 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 resin. Copolymer resin, polyvinyl acetal resin, diallyl phthalate resin, polysulfone resin, polycarbonate resin, acetic acid-crotonic acid copolymer resin, polyarylate resin, butyral resin, styrene-maleic anhydride copolymer resin, rosin-phenol modification These include resins, casein, etc., and these can be used alone or as a copolymer, or a mixture of two or more kinds. 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, polyvinylcarbasol, phenanthrene, N-ethylcarbazole, 2.5
-diphenyl-1,3,4-oxadiazole, 2.5
-bis(4-diethylaminophenyl) -1,3,4
-Oxadiazole, 4,41-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 2,4
．． 5-) Lis(p-diethylaminophenyl)oxazole, 2.5-bis(p-diethylaminophenyl)-
1,3,4-)riazole, 1-phenyl-3-(p-
Examples of electron transport substances include diethylaminosteryl)-5-(p-diethylaminophenyl)-2-pyrazoline, p-diethylaminobenzaldehyde-diphenylhydrazone, and N-ethyl-carbazole-3-carboxaldehyde-diphenylhydrazone. is 2-
Nitro-9-fluorenone, 2.7-dinitro-9-fluorenone, 2.4.7-)nitro-9-fluorenone, 2-nitrobenzoteophenone, dinitroanthracene, dinitroacridine, dinitroanthraquinone, etc. .

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 binder is added in an amount of 0.1 to 10 times the weight of the charge transport material, preferably 0.2 to 5 times the weight of the charge transport material.

Examples of the conductive support used for producing the photoreceptor of the present invention include a metal plate, conductive paper, conductive niblastic film, metallized film, metal cylinder, and plastic cylinder treated with metallization or metal foil. There is. Examples of solvents used for dispersing or dissolving azo pigments and charge transport substances together with binders and coating them on these supports include tJ,) toluene, xylene, monochlorobenzene, chloroform, dichloroethane, and trichloroethylene. , methylene chloride, dioxane, tetrahydro 7:5, ethyl acetate, butyl acetate, methylselonulp, methylselonulp acetate.

Examples include 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 Exemplary Pigment 4 according to the present invention described above and Pigment R-1 below as a comparison. R-2, R-3 buttons and R-4 were mixed with 1 part by weight each of < -1 < -3, 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. The pigment dispersion thus obtained was applied onto an aluminum support for Ps plate (anodized, manufactured by Agfa) using a wire paper, each having a film thickness of about 0.
A 2-0.3 micron charge generation layer was provided.

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

Regarding this photoreceptor, it was
-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)
, 1 (1 open tffl (7) iK position Vd (V) '
DD=Vd/VoX100 (%) was measured.

In addition, the exposure RE1/2 (1
uxe seconds) was calculated. Next, this photoreceptor ft50001
After exposing it to the light of a fluorescent lamp with an illuminance of ux for 5 minutes and leaving it in a dark place for 30 seconds, the charging potential V that you want to perform the characteristic test of the same machine as above.
o(V), E 1/2 (1ux-sec)DD@) was 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.

From the results in Table 1, the photoreceptor using the azo pigment of the present invention has
It can be seen that the charging potential Vo, sensitivity, and pre-exposure characteristics are all very good.

Next, the surface potential of these photoreceptors after being exposed with an exposure amount of t-5Qlux·sec, that is, the residual potential E50 (V)'
I asked for Similar measurements were repeated 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 2.

From the results in Table 2, it can be seen that the photoreceptor using the azo pigment (4) of the present invention also has excellent repeated use characteristics.

Example 2 Exemplary pigments 11, 13 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, and 1 part by weight of polycarbonate resin Panlight 1250 manufactured by Kijin Kasei Co., Ltd. were added to 50 parts by weight of dichloroethane. The mixture was dispersed for 2 hours using a paint conditioner. 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-diethylaminosteryl)-5-Cp-diethylaminophenyl) pyrazoline, 2 parts by weight of polyester resin (Pylon-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 coating liquid to produce a cylinder photoreceptor. The charged potential Vo (V) & general sensitivity "1/! (lux m sec)" of this photoconductor were determined in the same manner as in Example 1, and then monochromatic light with a wavelength of 600 nm was obtained by spectroscopy using a non-rogen lamp with a spectrometer. Light (surface illuminance on photoreceptor 1 μW/f
fl ), the time (seconds) required for the surface potential to decrease to the initial potential of 14 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.

Table 3 From the above results, it was confirmed that all of the photoreceptors of the present invention had excellent characteristics not only in general sensitivity but also in red sensitivity, compared to the characteristics of comparative photoreceptors.

Example 3 Exemplary pigments 12.39.67 and 8 according to the invention as described above
1 and the following pigments R-8 and R9 for comparison: 1 part by weight each, polyarylate resin (Unitika U-x
oo) parts of li were mixed with 100 parts by weight of dichloroethane and dispersed in the same manner as in Example (1) above to obtain a coating dispersion. As a support, an aluminum support for Pa plates (anodized, manufactured by Agfa) was coated in the same manner, and a charge generation layer having a thickness of about 0.2 to 0.3 microns was provided in each case.

Next, a coating solution prepared by dissolving 1 part by weight of p-dibenzylaminobenzaldehyde-diphenylhydrazone and 1 part by weight of polyarylate resin as a charge transport material in 10 parts by weight of dichloroethane was applied onto the charge generation layer in the same manner. A laminated photoreceptor having a charge transport layer approximately 15 microns thick was prepared. Regarding this photoreceptor, white light sensitivity and 600
The spectral sensitivity in nm was measured. The results are shown in Table 4.

-9 Table 4 As is clear from the above, the method of the present invention provides an electrophotographic photoreceptor with excellent red reproducibility of originals, high sensitivity, low residual potential, and excellent pre-exposure characteristics and repeated use characteristics. I can do things.

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] ▲ Numerical formulas, chemical formulas, tables, etc. Represents an atom, a halogen atom, or a cyano group. Also, Cp represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X represents Represents an atomic group necessary to form an aromatic ring or a heterocycle (these rings may be substituted or unsubstituted) by condensing with the benzene ring in the above formula to which a hydroxy group and Y are bonded. , Y has ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R^4 represents an alkyl group, phenyl group, or a substituent thereof, and R^5 represents a hydrogen atom, an alkyl group, a carbamoyl group, or a carboxyl group. group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a substituted or unsubstituted amino group, R^6 represents an alkyl group, an aromatic ring group, a heterocyclic group, or a substituent thereof, R^7 and R ^8 represents a hydrogen atom, an alkyl group, an aromatic ring group, a heterocyclic group, or a substituted product thereof. However, R^7 and R^8 are never hydrogen atoms at the same time. Also, when Y is ▲There is a mathematical formula, chemical formula, table, etc.▼, R
^8 is never a hydrogen atom. W represents a divalent aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic divalent group containing a nitrogen atom in the ring. ]