JPH01234856A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body sufficient in sensitivity in the red color region, high in sensitivity, and superior in characteristics after repeated uses and durability by forming a photosensitive layer containing a specified azo pigment. CONSTITUTION:The photosensitive layer contains the azo pigment represented by formula I in which R1 is H, halogen, cyano, or the like; each of R2 and R3 is alkyl or aryl, each optionally same or different; and n is 1, 2, or 3. This azo pigment can be easily synthesized by diazotizing the corresponding amino derivative, allowing a base to act to execute coupling reaction with 6-hydroxy-2- pyridone derivative in dimethylformamide or tetrahydrofuran, thus permitting the obtained photosensitive body to have sufficient sensitivity in the red color region, and superior durability.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field The present invention relates to an electrophotographic photoreceptor, and more particularly to a photoreceptor having a photosensitive layer containing an azo pigment using a 6-hydroxy-2-pyridone derivative.

(B) Prior art and its problems Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and silicon have been known to be used as electrophotographic photoreceptors, and have been extensively studied and put into practical use. has been made into In recent years, in contrast to these inorganic materials, research into organic photoconductive materials has progressed actively, and some have been put into practical use as electrophotographic photoreceptors.

- Numerically speaking, inorganic materials have problems such as thermal stability, deterioration of properties due to crystallization, and manufacturing difficulties in the case of selenium photoreceptors, and moisture resistance, durability, etc. in the case of cadmium sulfide. Compared to the current situation, which is not always satisfactory due to problems such as industrial waste disposal, organic materials have good film forming properties, excellent flexibility, light weight, and transparency. Its practical application is increasingly attracting attention because it has advantages such as good performance and ease of designing photoreceptors for a wide range of wavelengths by using an appropriate sensitization method.

By the way, the photoreceptor used in electrophotography technology is -
The following basic numerical properties are required.

In other words, (1) it has high charging properties against corona discharge in the dark, (2) (5) there is little leakage (dark decay) due to stray charged charges, and (3) it is possible to reduce the amount of charged charges by irradiation with light. (4) The residual bacterial charge after light irradiation is small.

However, to date, much research has been conducted on photoconductive polymers such as polyvinylcarbazole as organic photoconductive materials, but these do not necessarily have sufficient film properties, flexibility, or adhesive properties. It is difficult to say that it has sufficient basic properties as a small photoreceptor.

On the other hand, with regard to organic low-molecular photoconductive compounds, by selecting the binder used to form the photoreceptor, it is possible to obtain a photoreceptor with excellent film properties, adhesion, flexibility, etc., and surface strength. However, it is difficult to find suitable compounds that can retain the properties of high sensitivity.

In order to improve this point, organic photoreceptors having higher sensitivity characteristics have been developed by assigning the carrier generation function and the carrier transport function to different substances. A feature of this kind of photoreceptor, which is called a functionally separated type, is that materials suitable for each function can be selected from a wide range, and a photoreceptor with arbitrary performance can be easily created, which has led to a lot of research. has been progressing.

Among such functionally separated type photoreceptors, many photoreceptors using organic dyes or organic pigments as carrier generating substances have been proposed. For example, photoreceptors using bisazo pigments or trisazo pigments are disclosed in, for example, JP-A-54-22834, JP-A-56-46237, and JP-A-57-1.
Although these photoreceptors are known in Japanese Patent No. 96241, the sensitivity of these photoreceptors is not necessarily sufficient for practical use.
It is desirable to improve the sensitivity of the - layer without satisfying the various requirements required for the electrophotographic process.

Especially when we limit the application to photoreceptors for general copiers,
Most conventional photoreceptors have absorption only in the short wavelength and long blue region, and since this does not reproduce the red color of the vermilion color, which is used in various types of divination, improvements in this respect are strongly desired. was.

(C) Purpose of the Invention The purpose of the present invention is to provide a photoreceptor having sufficient sensitivity even in the red region (near 600 nm), high sensitivity, and excellent characteristics and durability after repeated use.

(D> Structure of the Invention As a result of various studies, the present inventor discovered that a compound represented by the following general formula 1 works effectively as a charge generating substance for an electrophotographic photoreceptor, and completed the present invention. I ended up doing it.

That is, the electrophotographic photoreceptor of the present invention has the following formula: - Formula CI) [wherein, X represents a substituted or unsubstituted hydrocarbon or heteroaromatic ring, R1: hydrogen atom, halogen atom, cyan group, carboxyl R2 and R3: the same or different alkyl or aryl groups; n: an integer of 1.2 or 3; ] It is characterized by having a photosensitive layer containing an azo pigment represented by the following.

In this formula (I), X is benzene, naphthalene, fluorene, anthracene, anthraquinone,
Hydrocarbon aromatic rings such as fluorenone, pyrene, and zenatorein, heteroaromatic rings such as furan, thiophene, pyridine, indole, benzothiazole, and carbazole, and the above aromatic rings directly or with aromatic or non-aromatic groups. Examples of bonded compounds include triphenylamine, biphenyl, terphenyl, binaphthyl, diphenyloxadiazole, diphenylsulfone, diphenylmethane, diphenyl ether, stilbene, distyrylbenzene, distyrylcarbazole, distyrylanthracene, and the like.

Substituents for these rings include lower alkyl groups such as methyl and ethyl, lower alkoxy groups such as methoxy and ethoxy, dialkylamino groups such as dimethylamino and diethyl amino, halogen atoms such as chloro and bromine, and hydroxy groups. , a nitro group, a cyano group, a trifluoromethyl group, and the like.

Specific examples of R1 in formula (I) include hydrogen atoms, halogen atoms such as chloro and bromine, cyan groups, carboxyl groups, alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl, carbamoyl groups such as carbamoyl and phenylcarbamoyl; Or a nitro group can be exemplified.

Specific examples of R2 and R3 include alkyl groups such as methyl, ethyl, isobutyl and dodecyl, and aryl groups such as phenyl, tolyl, methoxyphenyl, chlorophenyl and 1-naphthyl.

To obtain the azo pigments of the invention, the corresponding amine derivatives are diazotized and then the corresponding coupling component, i.e. 6-
It can be easily synthesized by carrying out a coupling reaction between a hydroxy-2-pyridone derivative and a base in a suitable organic solvent such as N,N-dimethylformamide or tetrahydrofuran.

Examples of synthesis of the azo pigment of the present invention are shown below.

Synthesis Example (1) [Example Pigment 37, (R1=CN, Rz=
CH3, R3 = C6H5)) 10 g of acetoacetanilide, 5 ml of methyl cyanoacetate and 30 ml of ethanol
Add 3.35 g of potassium hydroxide into the stirring mixture of d.
After adding 85 g of 100 InIl ethanol solution,
Heat at ℃ for 5 hours.

The precipitated crystals are collected by filtration, dissolved in water, and acidified with hydrochloric acid. The crystals precipitated by standing were collected by filtration, thoroughly washed with diethyl ether, and then dried to obtain 5.69 crystals of (a).

Melting point 309-311° (decomposition), yield 44%.

Dissolve 252 mg of 2,5-bis(4-aminophenyl)oxadiazole in 20 d of DMF, add 4 d of 2N salt, and dissolve 14 ml of sodium nitrite at -10°C while stirring.
A solution of 5 mg dissolved in 2 m of water is added dropwise and reacted for 30 minutes to obtain a detrazonium salt. Next, (a>452my and triethanolamine 1, 6rIdl were mixed with DM F 2
The above detrazolinium salt solution was added to the solution dissolved in 0d while being cooled and stirred, and after reaction for 2 hours, the produced pigment was collected by filtration, washed with water, and further washed with acetone to obtain the desired pigment 37, (R1=CN, R-=CH3, R
3 =C e f-15>(b) 472m! Get J.

Melting point 330'C or higher, yield 65%.

Synthesis Example (2) [Exemplary Pigment 40, (R1=CN, Rz
=R 3 =Ce 15) ] (d) N, 3-
Synthesis literature of diphenylpropynamide (J. Or (),
ChOm. Volume 20, page 210 (1955))
Synthesized according to the following. Phenylpropinoyl chloride 22
The white crystals obtained by reacting 12.2 ml of 'j t3 and aniline in 150 ml of diethyl ether under ice-cooling were collected by filtration, crushed well in dilute hydrochloric acid and washed, and the crystals were washed with water, read, and dried. d) Crystal 23. 'NJ@get. Melting point 123.5-124.5° C1 Yield 78%.

(e) Synthesis of 3-cyano-1,4-diphenyl-6-hydroxy-2-pyridone 3.35 rIIl of methyl cyanoacetate was added to 60 d of absolute ethanol to completely dissolve it while cooling with water and stirring. Then (d) add 6.6 cJ. After returning to room temperature and stirring for 10 minutes, the mixture was heated under reflux for 2 hours.

The temperature was returned to room temperature, 93 ml of 0.5N was added, and the precipitated crystals were collected by filtration, washed with a small amount of water, and dried. Further, recrystallize with methanol to obtain crystal (e) of 4.25'7
get.

Melting point 274-276°C (decomposition), yield 49%.

(f) Exemplary pigment 40, (R1=CN, R2=R3-Ce
Synthesis of H5 According to the method of Synthesis Example (1), the desired pigment (
590 my of crystals of f> are obtained. Melting point: 330'C or higher, yield: 73%.

As specific examples of the azo pigment of general formula (I), the compounds shown below are preferably used. However, for the sake of simplicity, only the structure of X and the substitution position are shown.

(When A>n=1 (monoazo compound) [1] [2] [3] [4] (B) When n=2 (bisazo compound) [1] [2] [3] [4] [5] ] (C) In the case of n=3 (trisazo compound) [1] [2] [3] [4] The electrophotographic photoreceptor of the present invention contains the bisazo pigment in the photosensitive layer. It can be used in various ways, for example bisazo pigments can be used as binders (
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 embodiments include polynisder resin, acrylic resin, styrene resin, silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, and styrene-butadiene copolymer. resins, polyvinyl acetal resins, diallyl phthalate resins, polysulfone resins, polycarbonate resins, acetic acid-bicrotonic acid covalent polymer resins, polyarylate resins, butyral resins, styrene-maleic anhydride copolymer resins, rosin-phenol modified resins, casein, etc. These can be used alone or in the form of a copolymer or a mixture of two or more. The amount of these binders to be used is 0.1 to 5 times by weight, preferably 0.2 to 3 times the weight of the bisazo pigment.

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, phenan 1-rhein, N-ethylcarbazole, 2
, 5-diphenyl-'1,3,4-oxadiazole,
2,5-bis(4-diethylaminophenyl)-1,3
, 4-oxadiazole, 4,4'-bis(diethylamino)-2,2-1dimethyltrimethylmethane, 2,
4.5-tri(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-
Examples of the electron transport substance include carbazole-3-carboxaldehyde-diphenylhydrazone.
-nitro-9-fluorenone, 2,7-sinitro-9-
Examples include fluorenone, 2,4.7-dolinitro-9-fluorenone, 2-nitrobenzothiophenone, dinitroanthracene, dinitroacridine, and dinitroanthraquinone.

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 to be used is preferably in the range of 0.1 to 10 (8i), preferably 0.2 to 5 times the amount 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 plastic film, metallized film, metal cylinder, and plastic cylinder treated with metallization or metal foil. and so on. Examples of solvents used for dispersing or dissolving azo pigments and charge transport substances together with binders and coating them on these supports include toluene, xylene, monochlorobenzene, chloroform, dichloroethane, trichloroethylene, and methylene chloride. , dioxane, tetrahydrofuran, ethyl acetate, butyl acetate, methyl cellosolve, methyl seron rub acetate, cyclohexanone, methyl ethyl ketone, dimethyl formaldehyde, dimethyl sulfoxide, ethyl alcohol, propyl alcohol, butyl alcohol.

Next, examples of the present invention will be shown.

Example 1 1 part by weight of each of the exemplary pigment Nα62 according to the present invention and the following pigments R-1, R-2, R-3 and R-4 for comparison (the following are blanks), a polyarylate resin (Unitika U. -1
00>"f was mixed with 100 parts by weight of dichloroethane and dispersed together with glass beads in a paint conditioner device for 2 hours. The pigment dispersion thus obtained was anodized using a wire bar on an aluminum support for PSS application. , manufactured by Agfa), each with a film thickness of 0.2
A charge generating layer of ~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 photoreceptor was first charged in the dark by 16 KV corona discharge, and the initial potential (0) was determined. Next, when the surface was exposed to white light with a surface illuminance of 5 lux, the time (seconds) required for the surface potential to decrease to 1/2 of the initial potential was measured, and the half-reduction exposure @ (E1/2> was determined as the sensitivity.

Roughly, next, monochromatic light with a wavelength of 600 nm (surface illuminance on the photoreceptor 1 μW /
crA), the surface potential becomes 1 of the initial potential.
The time (seconds) for the reduction to /2 was measured, and the half-reduction exposure @ (E1/2<600>) was determined as the spectral sensitivity at 600 nm. The results are shown in Table 1.

(Left below) Example 2 Exemplary pigment No. 134, No. 1 according to the present invention
As a comparison with No. 36 and No. 137, the following pigment R-
5. 2 parts by weight of each of R-66 and R-7 (hereinafter referred to as margins), 1 mffi part of polycarbonate resin (Panlite-1250 manufactured by Yojin Kasei Co., Ltd.) were added to 50 parts by weight of dichloroethane, and dispersed in a pain conditioner for 2 hours. This dispersion was coated on the surface of an aluminum cylinder having an outer diameter of 60 m by a cylindrical pull-up coating method. 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 a polyester resin (Vylon-200) and 225 parts by weight of dichlorela 225 parts by weight were added. A charge transport layer having a thickness of 15 microns was formed by applying a coating liquid dissolved in the above to form a cylindrical photoreceptor. Table 2 shows the measurement results of the sensitivity of this photoreceptor.

(The following is a blank space) Example 3 144 Exemplary pigment Nα7, No. 11, according to the present invention
Na55, No, 77, N (111L N (1128,
For comparison with No. 145 and No. 165, 1 part by weight of each of the following face 'F4R-8' and 1 part by weight of polyarylate resin (U-100 manufactured by Unitika) were mixed with 100 parts by weight of dichloroethane, and the above Example ( A coating dispersion liquid was obtained by dispersing in the same manner as in 1). As a support, a PSS aluminum support anodized (manufactured by Agfa Corporation) was coated in the same manner, and a charge generation layer having a thickness of 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 is applied onto the charge generation layer in the same manner. A laminated photoreceptor with a charge transport layer of about 15 microns was prepared. The white light sensitivity of this photoreceptor was measured in the same manner as in Example (1).

The results are shown in Table 3.

Claims (1)

[Claims] General formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [I] [In the formula, X: represents a substituted or unsubstituted hydrocarbon-based or heteroaromatic ring, R_1: hydrogen atom, halogen atom , represents a cyano group, carboxyl group, alkoxycarbonyl group, carbamoyl group or nitro group, R_2 and R_3: represent the same or different alkyl group or aryl group, n: represents an integer of 1, 2 or 3. ] An electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by: