JPS63135945A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body which has high sensitivity and lessened residual voltage, and to reduce increase of the voltage at a light part in the case of repeating charge and exposure, thereby to stabilize the titled body by incorporating a specific tetrakisazo pigment and a specific polycarbonate Z resin to the titled body. CONSTITUTION:The titled body has a photosensitive layer contg. at least one kind of the tetrakisazo pigment shown by formula (1) and the polycarbonate Z resin shown by formula (2). In the formulas, A is a coupler residue contg. a phonolic OH group, (n) is a mean polymerization degree and is a range of 50-5,000. The degree capable of forming a barrier layer which hinders transfer of charge on an interface between the pigment particle and the resin at the time of irradiating light decreases remarkably by combinating said pigment and a resin other than the polycarbonate Z resin. The benzene ring and cyclohexyl ring contd. in the polycarbonate Z resin structure makes easily the transfer of charge, thereby improving the sensitivity. Thus, the stability of the titled body is improved, and the producibility of the titled body is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor having a photosensitive layer with improved characteristics by containing a specific tetrakisazo pigment and a polycargonate resin. Regarding photographic photoreceptors.

[Conventional technology]

Conventional electrophotographic photoreceptors include those using inorganic photoconductive substances such as selenium, cadmium sulfide, zinc oxide, and amorphous silicon, and those using photoconductive polymers such as poly-N-vinylcarbasol and polyvinylanthracene. Those using various low-molecular organic photoconductive substances such as noethylaminobenzaldehyde (N,N--) phenylhydrazone, and those in which organic pigments are dispersed are known. Among these, Sudanare is an organic pigment used in electrophotographic photoreceptors.

azo pigments such as de, guiampurus, disazo pigments, quinone pigments such as algol yellow and pyrenequinone, quinocyanine pigments, perylene pigments, insogo pigments such as indigo and thioindib, bisbenzimidazole pigments such as India First Orange Toner, copper phthalocyanine, etc. Examples include 7 talocyanine pigments and quinacridone pigments.

Although some photoreceptors having these pigments dispersed therein have been put into practical use, it cannot be said that the sensitivity is still fully satisfied.

This is because pigments require a binder to form a film, and this binder inhibits the movement of charges.

Therefore, when using pigments, it is essential to use a binder that is optimal for the pigments.

On the other hand, in the case of a functionally separated photosensitive layer in which the photosensitive layer is divided into a charge generation layer that generates charges and a charge transport layer that transports the charges, a pigment is used in the charge generation layer.

In this case, not only the binder in the charge generation layer but also the binder in the charge transport layer becomes a factor that determines the sensitivity.

In other words, the key to high sensitivity is to efficiently inject the charges generated in the charge generation layer into the charge transport layer, but if the combination of the pigment in the charge generation layer and the binder in the charge transport layer is poor, both layers may A barrier to charge injection is formed at the interface, reducing injection efficiency. Therefore, even in the functionally separated photosensitive layer, a binder for the charge transport layer that is optimal for the pigment is essential.

By the way, polycargonate resins generally have characteristics such as transparency, electrical insulation imageability, high torsion resistance, do not interfere with the charge mobility of charge transport materials, and good mechanical durability and abrasion resistance. It has been proposed to be used as a binder in a charge transport layer. However, the binuphenol/l represented by the following formula (n1d50~5000), which is a proxy for polycargonate resin,
/A polycargonate resin (hereinafter referred to as polycargonate A)
Due to the high crystallinity of the polymer, the resin has poor solubility in the solvent used in the coating solution, and the solution gels within a few days, making it unusable, and the productivity of the photoreceptor suffers.

[Problem that the invention seeks to solve]

The present invention addresses the above-mentioned conventional technical problems and provides an electrophotographic photoreceptor with higher sensitivity by combining a specific pigment contained in a photosensitive layer and a binder resin suitable for the pigment. With the goal.

Still another object is to provide an electrophotographic photoreceptor with improved productivity and stable quality.

[Means for solving problems]

According to this button, Tet2Kisua! is represented by the following general formula (1)! There is provided an electrophotographic photoreceptor characterized by having a photosensitive layer containing at least [l of a pigment and a polycarbonate z resin represented by the following general formula (2).

General formula (1) (In the formula, A represents a force having a phenolic OH group and a Schiller residue.) General formula (2) (In the formula, n represents an average degree of polymerization, ranging from 50 to 5000. ) The phenolic O represented by human in the general formula (1) above
The force having an H group, the f2-residue, is represented by the following general formula (3
) to (9).

In the formula, X is a naphthalene ring fused with a benzene ring, 7
Indicates a residue necessary to form a polycyclic aromatic ring or a heterocycle selected from a nthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a hentuna 7-tofuran ring, and a diphenylene sulfide ring, especially a 7-talene ring. , an anthracene ring, a benzcarbazole ring, and a carbazole ring are more preferable, and R1 and R2 are a hydrogen atom, a group selected from an alkyl group that may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group, or R1゜Indicates a cyclic amine group formed with the nitrogen atom to which R2 is bonded; specific examples of alkyl groups include methyl, ethyl, globyl, butyl, etc.; specific examples of aralkyl groups include benzyl, 7enether, naphthylmethyl, etc. Specific examples of the aryl group include phenyl, diphenyl, naphthyl, and anthryl, and examples of the heterocyclic group include carbazole, nobe7zo7lane, benzimidacylon, benzthiazole, thiazole, and biricin.

Examples of the substituents that the above alkyl groups, aralkyl groups, aryl groups and heterocyclic groups may have include methyl, ethyl, glopyral alkyl groups, methoxy, ethoxy,
Alkoxy groups such as globoxy, heptad atoms, chlorine atoms,
Examples include halogen atoms such as a bromine atom and an iodine atom, a nitro group, a cyano group, and substituted amino groups such as dimethylamino, dipenzolamino, and nophenylamino.

General formula (4) General formula (5) Formula (4L) In the general formula (5), R3 and R4 represent a group selected from an alkyl group, an aralkyl group, and an aryl group that may have a substituent.

Specific examples of the above R5 and R4 include the above general formula (3)
, the same example as R1 and R2 in (4) can be given.

General Formula (6) In General Formulas (6) and (7), Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring.

The divalent groups of the aromatic hydrocarbons mentioned above include the divalent groups of monocyclic aromatic hydrocarbons such as 0-7 enylene, o-naphthylene, perinaphthylene, 1.2-77 slylene, 9.10-
Examples include divalent groups of polycyclic aromatic hydrocarbons such as 7-enanethrylene, and examples of divalent groups of heterocycles containing a nitrogen atom in the ring include 3,4-pyrazolediyl, 2,3-
Pyrinonenoyl, 4.5-pyrimidinoyl, 6.7-
Examples include divalent 5- or 6-membered heterocyclic groups such as imidazolediyl, 5,6-penzimidazolezoyl, and 6,7-chiralindiyl.

In the formula, R6 and R6 are a hydrogen atom, a group selected from an alkyl group that may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group, or a 5-membered group together with the carbon atom to which R5 and R6 are bonded. Indicates a residue forming a 6-membered ring, this 5- or 6-membered ring may have a fused aromatic ring, and z
is necessary to form a polycyclic aromatic ring selected from a naphthalene ring, an anthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphtho7rane ring, and a nophelene sulfide ring, or a heterocycle fused with a benzene ring. Residues are shown.

Specific examples of the alkyl groups mentioned above include methyl, ethyl, propyl, butyl, etc. Specific examples of the aralkyl groups include benol, phenethyl, naphthylmethyl, etc. Specific examples of the aryl groups include phenyl, naphthyl, anthryl,
Specific examples of groups such as pyrenyl and heterocyclic groups include groups such as pyridyl, chenyl, furyl, and carbazoyl, and further substituents that the above groups may have include fluoride, elementary atoms, chlorine atoms, Halogen atoms such as bromine and iodine atoms, alkyl groups such as methyl, ethyl, propyl, butyl, methoxy, ethoxy,! Examples include alkoxy groups such as lopoxy and butoxy, nitro groups, cyano groups, and substituted amino groups such as dimethylamino, diethylamino, diethylamino, zopennolamino, diphenylamino, morpholino, piperitno, and pyrrolidino. A specific example of a group that forms a 5- or 6-membered ring with the bonded carbon atom of R4, and this 5- or 6-membered ring may have a fused aromatic ring is cyclo. pencilidene,
Examples include groups such as cyclohexylidene and 9-xanthenylidene.

In the formula, R2 and R8 are a hydrogen atom, a group selected from an alkyl group that may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group, or a 5- or 6-membered group together with the carbon atom to which R7*16 is bonded. Indicates a residue forming a ring, and this 5- or 6-membered ring may have a fused aromatic ring,
z is a polycyclic aromatic ring selected from a naphthalene ring condensed with a benzene salt, an anthracene ring, a carbazole ring, a henzcarpazole ring, a dibenzofuran ring, a pencinnatyl heptan ring, and a nophenylene sal hepido ring, or a hetero Residues necessary to form a ring are shown.

Specific examples of the alkyl group in the above group include methyl, ethyl,
Examples of groups such as propyl and butyl, specific examples of aralkyl groups include benol, 7enethyl, and naphthylmethyl; specific examples of aryl groups include groups such as phenyl, diphenyl, naphthyl, anthryl, and pyrenyl; and heterocyclic groups. Specific examples include groups such as pyridyl, chenyl, suryl, and carbazoyl, and examples of substituents that the above groups may have include halogen atoms such as a, elementary atoms, salt atoms, bromine atoms, and iodine atoms. , alkyl groups such as methyl, ethyl, globil, butyl, methoxy, ethoxy, glopoxy,
Examples thereof include alkoxy groups such as ethoxy, nitro groups, cyano groups, dimethylamino, noethylamine, dimethylamino, zopendylamino, sophenylamino, heptulfolino, piperidino, and substituted akino groups such as pyrolituno.

5-membered or 6-membered with the bonded carbon atoms of R, R8 above
Specific examples of groups which are residues forming a membered ring, and this 5- or 6-membered ring may have a condensed aromatic ring include groups such as cyclopentylidene, cyclohexylidene, and 9-quitentenylidene. Can be mentioned.

Tetraquinoa represented by general formula (1)! Give an example of pigments.

First, the polycargonate Z resin of the general formula (2) used in the present invention differs from the conventionally used polycarbonate A resin in that it maintains the mechanical durability of the polycargonate resin while also It has good solubility in various solvents, and its solutions have good stability without gluing even after a long period of time, which greatly contributes to improving the productivity of photoreceptors.

Specific tetrakisazo pigments and polycargones of the present invention)
By combining the Z resin, the extent to which a barrier layer is formed at the interface between the pigment particles and the resin to prevent the movement of charges during light irradiation is much smaller than when combined with other resins (polycarbonate). It is believed that the benzene ring and cyclohexyl group in the Z resin structural formula facilitate charge transfer and improve sensitivity.

The form of the electrophotographic photoreceptor according to the present invention is (,)
Photosensitive layer (b) in which a tetrakisazo pigment is dispersed in a polycargonate z resin.
) Z resin and charge transport substance (electron donating compound and/or
A photosensitive layer (,) in which a tetrakisazo pigment is dispersed in a binder resin (polycarbonate resin or other resin) is used as a charge generation layer; polycargonate z
A functionally separated photosensitive layer (d) consisting of a stack of charge transport layers containing a resin and a charge transport substance! Examples include a functionally separated photosensitive layer laminated with a charge generation layer f containing a tetrakisazo pigment and a polycargonate z resin on a charge transport layer.

Examples of electron-donating compounds include polycyclic aromatic rings such as anthracene, pyrene, 7-enanthrene, and coronene in the main chain or side chain;
or indole, carbazole, oxixole, isoozosol, thiazole, imidazole, pyrazole,
Examples include compounds having nitrogen-containing heterocycles such as oxanoazole, pyrazoline, thiazazole, and triazole, hydrazone compounds, and aromatic amino compounds.

Examples of electron-accepting compounds include aliphatic cyclic compounds, aromatic compounds, and heterocyclic compounds having electron-accepting substituent groups such as nitro, nitroso, and cyano groups, such as tetracyanoethylene, trinitrobenzene, Dinitroacetophenone, trinitroanisole, tetranitronaphthalene, terephthalonitrile, in7talonitrile, benzoyl cyanide, quinoline cyanide, cyanopyridine, nitroanthracene, dunitrofluorenone,
trinitronefluorenone, tetranitrofluorenone,
Examples include tetracyanopyrene.

Electron-donating compounds are not preferred, in part because of their carcinogenicity and other harmful properties.

When using an electron donating compound, the above-mentioned form (,) is used for negative charging, and the form (d) is used for positive charging.

The charge transport layer contains a charge transport material and a resin in a ratio of 5:1 to 1:2 (
weight ratio], and the film thickness is 5 to 20 μm.
That's about it.

In the above form (C), the binder resin for the tetrakisazo pigment is polycargones) Z, lyester, ?
Rivinylbendale, polyvinylbutyral, holvinylpyrrolidone, methylcellulose.

Polyacrylic esters, cellulose esters, etc. are used as appropriate.

Dispersion is done by mixing the pigment into the resin solution and then using a Gale mill.

Conventional methods such as a roll mill, sand mill, and colloid mill can be used.

The thickness of the charge generation layer is 0.01 to 1μ, preferably 0.05μ.
It is about 0.5μ. When it is formed on the charge transport layer, it is thicker, about 0.5 to 5 μm. The ratio of pigment to resin is about 5:1 to 1:2.

〔Example〕

Hereinafter, the present invention will be further explained with reference to Examples.

Examples 1 to 6 A 60φ×260mm aluminum cylinder with a wall thickness of 0.5 ysm was prepared as a base.

Next, copolymerized nylon (product name: CM8000, Azuma)
(manufactured by Dainippon Ink) and 4 parts of Tie 7'8 nylon (product name: U, Kamide 5003, manufactured by Dainippon Ink ■) with 5 parts of methanol.
The solution was dissolved in 50 parts of n-butanol and dip coated on the conductive layer to form a polyamide undercoat with a thickness of 0.6 μm.

Next, t-10 parts of the disazo pigment shown in No. 1i selected from the above-mentioned exemplified compounds and 10 parts of polyvinyl butyral resin (trade name: Esle, BM-2 manufactured by Sekisui Chemical Co., Ltd.) were added together with 120 parts of cyclohexanone in a sand mill apparatus. 30 parts of methyl ethyl ketone was added to the zero dispersion that had been dispersed for 10 hours, and the mixture was coated on the undercoat layer to form a charge generation layer with a thickness of 0.15 p.

Next, 10 parts of polycargonate Z resin (manufactured by Mitsubishi Gas Chemical Company, weight average molecular weight: 120,000) was prepared and dissolved in 80 parts of monochloropentene along with 10 parts of a hydrazone compound having the following structural formula.

This was coated on the charge generation layer to form a charge transport layer with a thickness of 16 μm.

The thus produced photoreceptor was subjected to -5,6 kV corona charging, image exposure, dry toner development, t-transfer to plain paper, and urethane rubber blade (hardness 70°, pressure 5 pw/
cwt% (at an angle of 20° to the photoreceptor) lJ-
The electrophotographic properties were evaluated by attaching it to an electrophotographic copying machine that has a printing process and the like. When measuring the potential, the dark potential (VD
) was −7O0v and the potential (VL) when exposure of 10 lux·sec was given was as shown in Table 1.

Comparative Examples 1 to 4 Photoreceptors were prepared in the same manner as in Example 1, except that organic pigments A to D below were used in place of the tetrakisazo pigment of Example 1. The measurement results of the characteristics are shown in Table 1.

Organic Pigment Compound A β-type Phthalocyanine (manufactured by Dainippon Ink Chemical ■) As mentioned above, all of the photoreceptors of Examples had higher sensitivity than those of Comparative Examples, and clear images without fogging were obtained.

Example 7 A photoreceptor was produced in the same manner as in Example 1, except that the tetrakisazo pigment of Exemplified Compound A4 was used instead of the tetrakisazo pigment of Exemplified Compound A1.

Comparative Examples 5 to 8 When forming the charge transport layer in Example 7, the following resins were used in place of the polycargenate z resin.

Comparative Example 5 Acrylic resin (product name: BR-80 Mitsubishi Rayon Rip Comparative Example 6 Polystyrene resin (product name Nistylon 479 manufactured by Asahi Kasei) Comparative Example 7 Phenoxy resin (product name: YP40 manufactured by Toto Kasei Manufacturing) Comparative example 8 Polyester resin (product Name: Pylon 300 manufactured by Toyobo] These photoreceptors were evaluated using an electrophotographic copying machine having the same process as in Example 1 (however, the exposure amount was 7.2 lux seconds. FF The initial vD, v
A comparison was made by looking at L, vD after 10,000 sheets, v, and the 10,000th image. The results are shown in Table 2.

As mentioned above, polycarmenate ZP is especially effective in terms of durability of 10,000 times! Examples of the present invention using B fat were excellent in sensitivity, potential stability, and image quality.

Comparative Example 9 When forming the charge transport layer in Example 7, polycarbonate A resin (trade name:
When using L-12 part 0 manufactured by Teijin Chemicals), the characteristics as a photoreceptor are vL and o- with experimental error.
There was not much difference with a change of 1 ov.

However, the viscosity of the coating liquid in which Polycarbonate A resin and the hydrazone compound were dissolved increased 3 to 4 times after 24 hours, and after 48 hours it became glued and lost its fluidity, whereas Polycarbonate 2 In the case of the resin, there was no viscosity change at all even after 48 hours, and the coating solution was extremely stable.

Example 8 Polyvinyl carbal (weight average molecular weight 60,000)
10 parts and 2 parts of m-terphenyl to 8 parts of monochlorobenzene
0 parts and dissolved in 20 parts of methylene chloride. Example 1
A charge transport layer having a thickness of 18 μm was provided by dip coating on the undercoat layer formed in the same manner as above.

Next, 10 parts of tetraquinazo of Exemplified Compound 6 was added to 250 parts of an 8% cyclohexanone solution of polycargonate Z resin (manufactured by Konjin Kasei, weight average molecular weight 150,000).
Dispersion was carried out using a sand mill device for 10 hours.

This dispersion was coated onto the charge transport layer without rotating the drum. In this way, a charge generation layer with a thickness of 3 μm was formed. This electrophotographic photoreceptor was attached to the same electrophotographic copying machine as in Example 1 and evaluated. However, the corona charge is +5.2kV, resulting in a V of -1700V.
, 7.5hy x-seconds, vL is 150
A good image could be obtained with v, and the same results as in Example 7 could be obtained.

On the other hand, even if a photoreceptor was made using each of the resins shown in Comparative Examples 5 to 8 in place of the polycargonate Z resin in Example 8, the evaluation of characteristics was still the same as in Comparative Examples 5 to 8. there were.

〔Effect of the invention〕

As per the present invention, certain tetraquinoa! A photosensitive layer containing a pigment and a specific polycargonate z resin has high sensitivity and low residual potential, and is stable without increasing bright area potential when charging and exposure are repeated.

In addition, since the polycargonate Z resin is present on the surface, the surface has high hardness and excellent lubricity, which prevents scratches and improves mechanical durability. Furthermore, the solution of polycargonate z resin has good storage stability as a coating liquid, so it can improve productivity and contribute to quality stabilization.

Claims (5)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one tetrakisazo pigment represented by the following general formula (1) and a polycarbonate Z resin represented by the following general formula (2). General formula (1) ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (1) (In the formula, A represents a coupler residue having a phenolic OH group.) General formula (2) ▲ Contains mathematical formulas, chemical formulas, tables, etc. Yes▼(2) (In the formula, n indicates the average degree of polymerization and is in the range of 50 to 5000.) (2) A in general formula (1) is represented by the following general formula (3) to (
9) The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is selected from coupler residues having a phenolic OH group represented by 9). General formula (3) ▲Mathematical formulas, chemical formulas, tables, etc.▼(3) (In the formula, X is a naphthalene ring fused with a benzene ring,
Indicates the residue necessary to form a polycyclic aromatic ring or heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring, R_1 and R_
2 is a hydrogen atom, a group selected from an alkyl group that may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group;
Alternatively, it represents a cyclic amino group formed together with the nitrogen atom to which R_1 and R_2 are bonded. ) General formula (4) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(4) General formula (5) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(5) (R_3 in general formulas (4) and (5) , and R_4 represent a group selected from an alkyl group, an aralkyl group, and an aryl group that may have a substituent.) General formula (6) ▲There are numerical formulas, chemical formulas, tables, etc.▼(6) General formula (7 ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(7) (Y in general formulas (6) and (7) is aromatic hydrocarbon 2
Indicates a valent group or a heterocyclic divalent group containing a nitrogen atom in the ring. ) General formula (8) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (8) (In the formula, R_5 and R_6 are hydrogen atoms, alkyl groups that may have substituents, aralkyl groups, aryl groups, and heterocyclic groups. or a residue that forms a 5- or 6-membered ring with the carbon atom to which R_5 or R_6 is bonded, and this 5- or 6-membered ring may have a fused aromatic ring; Naphthalene ring fused with benzene ring,
Indicates a residue necessary to form a polycyclic aromatic ring or a heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring. ) General formula (9) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (9) (In the formula, R_7 and R_8 are hydrogen atoms, alkyl groups that may have substituents, aralkyl groups, aryl groups, and heterocyclic groups. or a residue that forms a 5- or 6-membered ring with the carbon atom to which R_7 or R_8 is bonded, and this 5- or 6-membered ring may have a fused aromatic ring; Naphthalene ring fused with benzene ring,
Indicates a residue necessary to form a polycyclic aromatic ring or a heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring. ) (3) The photosensitive layer comprises a tetrakisazo pigment of the general formula (1) as a charge generating material dispersed in a charge transporting material and a polycarbonate Z resin of the general formula (2); or The electrophotographic photoreceptor according to item 2. (4) The photosensitive layer is a lamination of a charge generation layer containing a tetrakisazo pigment of general formula (1), a charge transport material, and a charge transport layer containing a polycarbonate Z resin of general formula (2). The electrophotographic photoreceptor according to item 1 or 2. (5) The photosensitive layer is obtained by laminating a charge generation layer containing a tetrakisazo pigment of general formula (1) and a polycarbonate Z resin of general formula (2) on a charge transport layer, or 2. The electrophotographic photoreceptor according to item 2.