JPS6278562A - Electrophotogrpahic sensitive body - Google Patents

Abstract

PURPOSE:To form a photosensitive layer having high sensitivity, hardly undergoing mechanical surface deterioration and also having high durability by using a specified disazo pigment and polycarbonate Z resin. CONSTITUTION:This electrophotographic sensitive body has a photosensitive layer contg. at least one kind of disazo pigment represented by formula 1 and polycarbonate Z resin represented by formula 2. The disazo pigment represented by the formula 1 has higher sensitivity than other org. pigment, undergoes less deterioration by irradiated light and also has higher durability. The polycarbonate Z resin represented by the formula 2 has satisfactory transparency, high electric insulation and dielectric strength. The surface of the resin is hard, has moderate lubricity and hardly undergoes mechanical wear. The resin shows superior stability when dissovled in a solvent.

Description

Detailed Description of the Invention [Industrial Application Field] 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 disazo pigment and a polycarbonate z resin. Regarding the body.

[Prior Art] Conventional electrophotographic photoreceptors include those using inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and amorphous silicon, and those using photoconductive materials such as poly-N-vinylcarbazole and polyvinylanthracene. There are known photoconductive materials using various low-molecular organic photoconductive substances such as polymers or diethylaminobenzaldehyde-N,N-diphenylhydrazone, and those in which organic pigments are dispersed. Among these, the organic pigments used in electrophotographic photoreceptors include Sudan Red,
Azo pigments such as Guianpuru, disazo pigments, quinone pigments such as algol yellow and pyrene quinone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, bisbenzi imiguzol pigments such as India First Orange toner, copper phthalocyanine, etc. Examples include phthalocyanine pigments and quinacridone pigments.

Although some photoreceptors having these pigments dispersed therein have been put to practical use, they are not fully satisfactory in terms of sensitivity.

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 by light 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 of the charge generation layer but also the binder of the charge transport layer becomes a factor in determining 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, the interface between the two layers This creates an injection barrier and reduces injection efficiency. Therefore, even in the functionally separated photosensitive layer, it is essential to select a binder for the charge transport layer that is optimal for the pigment.

[Problems to be Solved by the Invention] In view of the above-mentioned conventional techniques, the present invention solves the following problems by combining a pigment contained in a photosensitive layer and a binder resin.
The purpose is to provide an electrophotographic photoreceptor with higher sensitivity.

Still another object is to provide an electrophotographic photoreceptor with excellent production stability.

[Means and effects for solving the problems] The present invention uses at least one disazo pigment represented by the general formula (1) described later as a pigment, and polycarbonate z8I represented by the general formula (2) described later as a binder. The above objective was achieved by combining it with fat.

Specifically, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing at least one disazo pigment represented by the following general formula (1) and a polycarbonate resin represented by the following general formula (2). It consists of

In the formula, A represents a coupler residue having a phenolic OH group.

In the formula, n represents the average degree of polymerization and is in the range of 50 to 5,000.

According to the invention, the disazo pigment represented by General Sha (1) has high sensitivity, less deterioration due to light irradiation, and high durability compared to other organic pigments.

Furthermore, by combining with the polycarbonate Z resin represented by the general formula (2), a highly durable photosensitive layer with high sensitivity and little mechanical surface deterioration can be formed.

Phenolic O represented by A in the above general formula (1)
As a coupler residue having an H group, the following general formula (3
) to (9).

In the general formula, or a polycyclic aromatic ring selected from a naphthalene ring, an anthracene ring, a cartazoole ring, a benzcarhezole ring, a dibenzofuran ring, a benzonaphthofuran ring, and a diphenylene sulfide ring formed by condensation with a benzene ring, or Residues necessary to form a telo ring are shown, and among them, a naphthalene ring, an andhracene ring, a benzcarbasol ring, and a carbazole ring are more preferable. R1 and R2 represent 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 cyclic amino group formed together with the nitrogen atom to which R1 and R2 are bonded, Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, etc. Specific examples of aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc. Specific examples of aryl groups include phenyl, diphenyl, naphthyl, anthryl, etc. Examples of the group and heterocyclic group include groups such as carbazole, dibenzofuran, penzimigsolone, benzthiazole, thiazole, and pyridine.

Examples of the substituents that the alkyl group, aralkyl group, aryl group, and heterocyclic group may have include alkyl groups such as methyl, ethyl, and propyl, methoxy, ethoxy,
Flukoxy group such as propoxy, fluorine atom, chlorine atom,
Examples include halogen atoms such as bromine atoms and iodine atoms, nitro groups, cyano groups, and converted amino groups such as dimethylamino, dibenzylamino, and diphenylamino.

General formula R3 0 ■ General formula R4 In general formulas (4) and (5), RS 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 R3 and R4 include the above general formula (3)
, and the same examples as R1 and R2 in (4).

General Formulas In the 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 divalent groups of monocyclic aromatic hydrocarbons such as 0-phenylene, 0-naphthylene, perinaphthylene, 1,2-antrylene, S, 10
- Divalent groups of polycyclic aromatic hydrocarbons such as phenanthrylene are mentioned, and examples of heterocyclic divalent groups containing a nitrogen atom include, for example, 3,4-pyrazoldiyl, 2,3
-pyridinediyl, 4,5-pyrimidinediyl, 6.7
-imidazolediyl, 5. Examples include 5- or 6-membered heterocyclic divalent groups such as e-benzimidazolediyl and J7-chiralindiyl.

In the formula, R5 and R6 are a hydrogen atom, a group selected from an alkyl group which may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group, or a 5- or 6-membered ring together with the carbon atom to which R5 and R6 are bonded. This 5- or 6-membered ring may have a fused aromatic ring, and Z
is fused with a benzene ring to form a polycyclic aromatic ring selected from naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, penzonaphthofuranya and diphenylene sulfide ring, or a heterocycle. Required residues are indicated.

Specific examples of the above alkyl groups include methyl, ethyl, propyl, butyl, etc. Specific examples of the aralkyl group include benzyl, phenethyl, naphthylmethyl, etc. Specific examples of the aryl group include phenyl, diphenyl, naphthyl,
Specific examples of groups such as anthryl and pyrenyl, and heterocyclic groups include groups such as pyridyl, chenyl, furyl, carbazoyl, etc. Furthermore, as substituents that the above groups may have, fluorine atoms, chlorine atoms, Halogen atoms such as bromine atoms and iodine atoms, alkyl groups such as methyl, ethyl, propyl, butyl, alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, nitro groups, cyano groups, dimethylamino, diethylamino, dipropylamino, Examples include substituted amino groups such as dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolisif.

A residue that forms a 5- or 6-membered ring with the carbon atom to which R5 and R8 are bonded, and this 5- or 6-membered ring is
Specific examples of groups in which the member ring may have a condensed aromatic ring include groups such as cyclopentylidene, cyclohexylidene, and 9-xanthenylidene.

In the formula, R7 and R8 are a hydrogen atom, a group selected from an alkyl group, an aralkyl group, an aryl group, and a heterocyclic group which may have a substituent, or a 5- or 6-membered group together with the carbon atom to which R7 and R3 are bonded. Indicates a residue forming a membered ring, this 5- or 6-membered ring may have a fused aromatic ring, and Z
is fused with a benzene term to form a polycyclic aromatic ring selected from a naphthalene ring, an anthracene ring, a carbazole ring, a benzcarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, and a diphenylene sulfide ring, or a heterocycle. Required residues are indicated.

Specific examples of the alkyl groups mentioned above include methyl, ethyl, propyl, butyl, etc. Specific examples of the aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc. Specific examples of the aryl groups include phenyl, naphthyl, anthryl, diphenyl, etc. Specific examples of the group and heterocyclic group include groups such as pyridyl, chenyl, furyl, carbazoyl, etc.
Further, substituents that the above group may have include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, alkyl groups such as methyl, ethyl, propyl, butyl,
Alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, nitro group, cyano group, dimethylamine, diethylamino, dipropylamino, dibenzylamino, diphenylamino.

%) Lt Substituted amine groups such as holino, piperidino, and pyrrolidino are mentioned. A specific example of a group that forms a 5- or 6-membered ring together with the carbon atoms to which R7 and R8 are bonded, and this 5- or 6-membered ring may have a fused aromatic ring is cyclo Examples include groups such as pentylidene, cyclohexylidene, and 9-merenylidene.

Specific examples of the disazo pigment represented by the general formula (1) are shown below.

NO. Exemplary Compounds In addition to these exemplary pigments, there are many disazo pigments included in the general formula (1).

The polycarbonate Z resin represented by the general formula (2) has (a) good transparency, (b) high electrical insulation and withstand voltage, and (C) a hard surface with appropriate lubricity. ,
It has characteristics such as being resistant to mechanical wear, and (d) has excellent stability when dissolved in a solvent.

Ordinary polycarbonate resin, i.e. bisphenol A type polycarbonate resin shown by the structural formula, has the disadvantage that it easily gels when dissolved due to the high crystallinity of the polymer, making it unusable in about two days. They differ greatly in this respect.

By combining the specific disazo pigment of the present invention with polycarbonate Z resin, the extent to which a barrier layer is formed at the interface between the pigment particles and the resin to prevent charge movement during light irradiation is much greater than when combining with other than polycarbonate Z resin. The benzene ring and cyclohexyl group of the polycarbonate Z resin structure facilitate charge transfer,
It seems to improve sensitivity.

In the form of the electrophotographic photoreceptor according to the present invention, (a) a disazo pigment represented by general formula (1) (hereinafter referred to as "disazo pigment") is added to a polycarbonate Z resin in a total amount of 1 part.
．． The prestige layer.

(b) A photosensitive layer in which a disazo pigment is dispersed in a polycarbonate Z resin and a charge transport substance (electron donating compound and/or an electron accepting compound); (C) a disazo pigment dispersed in a binder resin (polycarbonate Z);
A functionally separated photosensitive layer in which a charge-generating layer is a layer dispersed in a resin or other resin, and a charge-transporting layer containing a polycarbonate Z resin and a charge-transporting substance is laminated thereon; (d) a charge-transporting layer; Examples include a functionally separated photosensitive layer in which a charge generation layer containing a disazo pigment and a polycarbonate Z resin is laminated on top of the layer.

Examples of electron-donating compounds include polycyclic aromatic rings such as anthracene, pyrene, phenanthrene, and coronene in the main chain or side chain, or indole, carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, and thiadiazole. , a compound having a nitrogen-containing heterocycle such as triazole, a hydrazone compound, an aromatic amine compound, and the like. Examples of electron-accepting compounds include aliphatic cyclic compounds, aromatic compounds, and heteroeyl compounds having electron-accepting substituents such as nitro, nitroso, and cyano groups, such as tetracyanoethylene, trinitrobenzene, Dinitroacetophenone, trinitrobenzene, tetranitronaphthalene, terephthalonitrile, isophthalonitrile, benzoyl cyanide, quinoline cyanide, cyanopyridine,
Examples include nitroanthracene, dinitrofluorenone, trinitrofluorenone, tetranitrofluorenone, and tetracyanopyrene.

Electron-accepting compounds are generally not preferred due to their carcinogenicity and other harmful properties.

When using an electron donating compound, the above-mentioned form (C) 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 (
The film thickness is 5 to 20p.
That's about it.

As the binder resin for the disazo pigment in the form (c) above, in addition to polycarbonate Z, polyester, polyvinyl benzafure, polyvinyl butyral, polyvinyl pyrrolidone, methyl cellulose, polyacrylic acid esters, cellulose esters, etc. are appropriately used. be done. Dispersion can be carried out by a conventional method such as a ball mill, roll mill, sand mill, or colloid mill after the pigment is mixed into the resin solution.

The thickness of the charge generation layer is 0.01 to 1 p, preferably 0.0
It is 5 to 0.5 cast.

When formed over a charge transport layer, it is thicker and has a thickness of 0.
The ratio of pigment to resin is about 5:1 to 1:2.

[Effects of the Invention] In the electrophotographic photoreceptor of the present invention, the photosensitive layer containing a specific disazo pigment and polycarbonate (Z) resin has high sensitivity and low residual potential, and furthermore, the bright area potential upon repeated charging and exposure is low. It is stable without rising, and since polycarbonate Z resin is present on the surface, the surface has a high altitude and has excellent lubricity, so it is less prone to scratches and can improve mechanical durability. .

Furthermore, since the polycarbonate (Z) resin solution has good storage stability, productivity can be improved and quality stability can also be improved.

[Examples] Examples 1 to 6 An aluminum cylinder with a wall thickness of 0.5 mm and a size of 60φ×260 mm was prepared as a base.

Next, 4 parts of copolymerized nylon (trade name: CM8000, unmanufactured in bundles) and type 8 nylon (trade name: Laccamite 50)
03, manufactured by Dainippon Ink Chemical Co., Ltd.) was dissolved in 50 parts of methanol and 50 parts of n-butanol, and the solution was dip-coated onto the above substrate to form a 0.6#L thick boronamide subbing layer.

Next, 10 parts of a disazo pigment selected from exemplary disazo pigments represented by the general formula (1) and polyvinyl butyral (trade name Kosuretsu BM-2, manufactured by Sekisui Chemical Co., Ltd.)
10 parts were dispersed together with 120 parts of cyclohexanone using a sand mill for 10 hours. Methyl ethyl ketone 3 in the dispersion
0 parts was added and coated on the undercoat layer to form a charge generation layer with a thickness of 0.15p.

Next, prepare 10 parts of polycarbonate Z resin (Mitsubishi Gas Kagaku Soso) with a weight average molecular weight of 120,000, and add 8 parts of monochlorobenzene along with 10 parts of a hydrazone compound having the following structural formula.
Dissolved in 0 parts. Coat this on the charge generation layer and
A charge transport layer having a thickness of 6 μm was formed.

Exemplary disazo pigments (1), (5), (10) of the above selections
, (15), (2o), and (28), Examples 1-
6 electrophotographic photoreceptor.

The electrophotographic photoreceptor thus produced was -5.6
Installed in an electrophotographic copying machine that has KV corona charging, image exposure, dry toner development, toner transfer to plain paper, cleaning process using a urethane rubber blade (altitude 70 @, pressure 5 kgw/cm2, angle 20' to the photoreceptor), etc. The electrophotographic properties were evaluated.

When the potential was measured, the dark potential (Vt, ) was -700■ 1
The potential (VL,) when exposure of 0 lux·sec was given was as shown in Table 1.

Comparative Examples 1 to 4 Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that the following organic pigments A to D were used in place of the disazo pigment in Example 1. Examples 1 to 4).

The measurement results of electrophotographic properties are shown in Table 1.

Organic pigment A β-type copper phthalocyanine (manufactured by Dainippon Ink Chemical Co., Ltd.; however, it is a pigment produced by successive hot filtration with water, ethanol, and methyl ethyl ketone) Table 1 Examples! (1) 155 185
Good example 2 (5) 150 180
Good Example 3 (10) 155
185 Good Example 4 (15) 150
160 Good Example 5 (20)
180 170 Good Good example e (28)
155 165 Good As above,
Compared to the comparative example, the electrophotographic photoreceptor of the example has higher sensitivity;
Furthermore, clear images with no fogging were obtained.

Example 7 An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the above-mentioned exemplary pigment (4) was used in place of the disazo pigment in Example 1.

Comparative Examples 5 to 8 Electrophotographic photoreceptors were produced in the same manner as in Example 7, except that the following resins were used in place of the polycarbonate Z resin used in forming the charge transport layer in Example 7.

Using these electrophotographic photoreceptors, an electrophotographic copying machine having the same process as in Example 1 (however, the exposure amount was 7.2
The evaluation was made by lux.seconds). The evaluation is initial V
l), VLJ and Vt after 10,000 sheets durability, VL
Further comparison was made by looking at the 10,000th image. The results are shown in Table 2.

Table 2 Examples? 700 145 B85 180
Comparative example 5 700 150 610 195 Comparative example 6 Bi12 145 B25 1!35
Comparative example 7 625 90 515 95 Comparative example 8 1380 +35 EII5 145
10,000th image Example 7 Good Comparative Example 5 Light fogging Comparative example 6 Light fogging Comparative example 7 Low image density Comparative example 8 Fog caused by scratches As above 1
In terms of durability over 10,000 cycles, the examples of the present invention using polycarbonate Z resin in particular proved to be superior in terms of sensitivity, potential stability, and image quality.

Comparative Example 9 Polycarbonate A resin (trade name Panlite L-1250, manufactured by Teijin Kasei Ltd.) was used in place of the polycarbonate Z resin used in forming the charge transport layer in Example 7, and the other conditions were the same as in Example 7. When an electrophotographic photoreceptor was prepared by this method, the characteristics as an electrophotographic photoreceptor varied from 0 to 10 V at V+-, which was about an experimental error, and there was no significant difference.

However, the viscosity of the resin solution of polycarbonate A resin and hydrazone compound increased 3 to 4 times after 24 hours, and it gelled and lost fluidity after 48 hours, whereas in the case of polycarbonate Z resin, There was no change at all even after 48 hours, and the solution was extremely excellent in terms of stability.

Example 8 Polyvinyl carbazole (weight average molecular weight 60,000)
10 parts and 2 parts of m-terphenyl to 8 parts of monochlorobenzene
0 parts and 20 parts of methylene chloride.

This was applied by dip coating onto the undercoat layer formed in the same manner as in Example 1 to provide a charge transport layer with a thickness of 18 μl.

Next, 10 parts of the disazo pigment of the exemplary pigment (6) was mixed with polycarbonate Z resin (manufactured by Teijin Kasei Ltd., weight average molecular weight: 15
The mixture was added to 250 parts of an 8% cyclohexanone solution (100%) and dispersed for 10 hours using a sand mill. This dispersion was spray coated onto the charge transport layer while rotating the drum. In this way, a charge generation layer having a thickness of 3 parts was formed.

This electrophotographic photoreceptor was attached to the same electrophotographic copying machine as in Example 1 and evaluated. However, corona charge is +5.2K
It was set to V.

As a result, when the Vp was 700 V and the light was applied for 7.5 lux seconds, the vL was 140 ■, and a good image could be obtained, and the same results as in Example 7 could be obtained.

On the other hand, even when electrophotographic photoreceptors were produced using different resins in the same manner as in Comparative Examples 5 to 8, the results were still similar to those in Comparative Examples 5 to 8.

Claims (5)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing at least one disazo pigment represented by the following general formula (1) and a polycarbonate Z resin represented by the following general formula (2). General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) In the formula, A represents a coupler residue having a phenolic OH group. General formula ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ (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 ▲ Numerical formula, chemical formula, table, etc. ▼ (3) In the formula, Indicates the residues necessary to form a polycyclic aromatic ring or heterocycle selected from sulfide rings, R_1 and R_2
represents a hydrogen atom, a group selected from an alkyl group which may have a substituent, an aralkyl group, an aryl group, and a heterocyclic group, or a cyclic amino group formed together with the nitrogen atom to which R_1 and R_2 are bonded. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (4) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (5) R_3 and R_4 in general formulas (4) and (5) have substituents. represents a group selected from an optional alkyl group, an aralkyl group, and an aryl group. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (6) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (7) Y in general formulas (6) and (7) is a divalent aromatic hydrocarbon or a heterocyclic divalent group containing a nitrogen atom in the ring. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (8) In the formula, R_5 and R_6 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 residue that forms a 5- or 6-membered ring with the carbon atoms to which R_5 and R_6 are bonded; this 5- or 6-membered ring may have a fused aromatic ring; Z is fused with a benzene ring; Residues necessary to form a polycyclic aromatic ring or heterocycle selected from naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (9) In the formula, R_7 and R_8 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 residue that forms a 5- or 6-membered ring together with the carbon atoms to which R_7 and R_8 are bonded; this 5- or 6-membered ring may have a fused aromatic ring; Z is fused to a benzene ring; Residues necessary to form a polycyclic aromatic ring or heterocycle selected from naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring. (3) The photosensitive layer comprises a disazo 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). The electrophotographic photoreceptor according to item 2. (4) The photosensitive layer is a laminate of a charge generation layer containing a disazo 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 a charge-generating layer containing a disazo pigment of general formula (1) and a polycarbonate Z resin of general formula (2) laminated on a charge transport layer. The electrophotographic photoreceptor according to item 2.