JPH05307274A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance durability by incorporating a specified bisazo pigment as an electric charge generating material and a specified diamine type compound as a charge transfer material and a polycarbonate and a specified polyester as a binder resin. CONSTITUTION:The electrophotographic sensitive body is provided on a conductive base with a photosensitive layer comprising a bisazo pigment represented by formula I as the charge generating material, a diamine type compound represented by formula II as the charge transfer material, and a polycarbonate and polyester represented by formula III as the binder resin. In formulae I-III, each of A<1> and A<2> is a coupler residue; R<1> is H, an aryl, or a heterocyclic group: (n) is 0 or 1; each of R<2>-R<7> is an alkyl, alkoxy, halogen, aryl, nitro, cyano, or alkylamino; each of (p) and (q) is 0, 1, 2, or 3; each of (k), (l), (m) and o is 0, 1, or 2; and one of A<3> and A<4> is a divalent group having an aromatic ring and the other is a divalent group having no aromatic ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus utilizing electrophotography such as an electrostatic copying machine and a laser beam printer.

[0002]

2. Description of the Related Art The electrophotographic method such as the Carlson process is a process of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge, and exposing the surface of the charged electrophotographic photosensitive member to an electrostatic latent image on the surface. An exposure step of forming an image, a developing step of bringing a developer into contact with the formed electrostatic latent image, and developing the electrostatic latent image into a toner image by toner contained in the developer; and a toner image Transfer step of transferring the toner to paper or the like, a fixing step of fixing the transferred toner image, and a transfer step,
And a cleaning step for removing the toner remaining on the photoconductor.

Recently, the electrophotographic photosensitive member used in the above-mentioned electrophotographic method is replaced with a main component containing an inorganic photoconductor such as selenium or cadmium sulfide, which is difficult to handle due to toxicity. Various so-called organic photoconductors using organic photoconductive compounds with low toxicity have been proposed. Such an organic photoreceptor has the advantages that it has good processability, is easy to manufacture, and has a high degree of freedom in functional design.

In general, such organic photoreceptors often use a function-separated type photosensitive layer containing a charge-generating material that generates a charge by light irradiation and a charge-transporting material that transports the generated charge. .. As a charge generating material used in the above electrophotographic photosensitive member, JP-A-1-202757 discloses a specific bisazo pigment. This bisazo pigment is represented by the following general formula (1).

[0005]

[Chemical 6]

(Wherein A ¹ and A ² are the same or different and each represents a coupler residue, R ¹ represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, an alkyl group,
The aryl group and the heterocyclic group may have a substituent. n represents 0 or 1. ) Such a bisazo pigment (1)
Has the advantages of being stable to heat and light, having high charge generation efficiency, high sensitivity, and excellent repeatability.

[0007]

By the way, in order to prepare a function-separated type organic photoreceptor using a charge generating material and a charge transporting material, sensitivity, potential holding property, potential stability,
A material with good matching that satisfies all electrophotographic characteristics such as residual potential must be selected. For example, no matter how much charge generation material generates sufficient charge, satisfactory electrophotographic characteristics cannot be obtained unless it is combined with a charge transport material capable of efficiently injecting and transporting the charge. ..

According to the above-mentioned JP-A-1-202757, by using the bisazo pigment represented by the general formula (1) in combination with various charge transport materials (carrier transfer substances), heat and light In contrast, it is disclosed that a stable photoconductor can be obtained. However, the charge generating material disclosed in the above publication has a phthalocyanine-based pigment, a perylene-based pigment, a fluorene-type bisazo pigment (JP-A-57-96345), and a perinone skeleton, which are commonly used charge generating materials. In comparison with oxadiazole type azo pigments having a coupler (Japanese Patent Laid-Open No. 59-229564), ozone and nitrogen oxide NOx generated in the copying machine are compared.
However, it has a drawback that it is prone to oxidative deterioration due to light and the like, and that the characteristics of the photoreceptor are likely to deteriorate. It is presumed that such oxidative deterioration of the bisazo pigment (1) occurs because ozone or the like adsorbs to the azo group and decomposes the azo group.

Such oxidative deterioration is caused by the above bisazo pigment.
It is promoted when (1) is used in combination with a charge transport material which is an electron donating compound. It is considered that when the electron-donating compound has a strong basicity, the electron-donating compound is coordinated with the azo group and increases the electron density of the azo group, so that it is easily attacked by ozone and nitrogen oxides. Be done.

Even if the charge-generating material and the charge-transporting material are well matched, if there is a problem with the physical properties of the binder resin that binds these materials to form the photosensitive layer, the electrophotographic characteristics will be comprehensively improved. Excellent photoreceptors cannot be obtained. For example, when the strength of the photosensitive layer is not sufficient or the adhesiveness of the photosensitive layer to the base is not sufficient, a cleaning blade pressed against the surface of the photosensitive member in the image forming apparatus, a toner scattering prevention felt, a charging roller, Due to physical impact from members such as transfer rollers and paper that comes into contact with the surface of the photoconductor during image formation, the surface may be easily scratched or the photosensitive layer may peel off. No good image can be obtained, and sufficient durability cannot be obtained no matter how good the repeatability is.

As the binder resin, the above-mentioned JP-A-1-202 is used.
Disclosed in Japanese Patent No. 757, polystyrene, (meth) acrylic acid ester, polycarbonate, polyester,
Various polymers such as butyral resin and epoxy resin are generally used. JP-A-57-4051 discloses that among the above polymers, polycarbonate is excellent in film forming ability and can form a tough photosensitive layer having excellent scratch resistance. However, since polycarbonate does not have sufficient adhesiveness with a conductive substrate or an underlayer, some pretreatment is required prior to layer formation in order to improve adhesiveness, which is a problem in terms of productivity and cost. .. JP 61
-132954 and JP-A-2-236555 disclose the use of a derivative of a polycarbonate in which silicon is introduced into the main chain as a binder resin. These derivatives are also different from ordinary polycarbonate. Similarly, the adhesiveness is not sufficient.

In order to solve the above-mentioned drawbacks of polycarbonate and improve the adhesiveness of the photosensitive layer, JP-A-59-71057 discloses blending polyester carbonate, and JP-A-62-212660. The publication discloses blending polyester or polyarylate. However, since the main chain of these polymers is rigid and the ester bond portion that contributes to the adhesiveness does not sufficiently act on the underlying substrate such as the conductive substrate, it is necessary to add a large amount to improve the adhesiveness. The polar group (electron-withdrawing group) therein acts as a carrier trap to reduce the sensitivity of the photoconductor, or a charge generation material under a high electric field,
There is a problem that the photo-oxidation deterioration of the charge transport material is promoted.

In particular, the bisazo pigment (1) is a molecule that does not have planarity like conventional phthalocyanine pigments and perylene pigments and has a high solubility in a solvent, and is dispersed in the photosensitive layer one by one. Since the number of copies is relatively large, it is more susceptible to photo-oxidation deterioration than the conventional pigment dispersed in the photosensitive layer as fine particles composed of a large number of molecules. Therefore, a large amount of polyester carbonate or the like cannot be blended, and the adhesiveness of the photosensitive layer cannot be sufficiently improved.

Therefore, it was not possible to obtain a photoreceptor having high sensitivity and repetitive characteristics without impairing the excellent characteristics of the bisazo pigment (1). The present invention has been made in view of the above circumstances, and uses the bisazo pigment represented by the general formula (1) as a charge generating material, and is a high-performance, high-performance electrophotographic photosensitive material excellent in durability. Intended to provide the body.

[0015]

Means and Actions for Solving the Problems The inventors of the present invention have conducted extensive studies on a charge transport material and a binder resin used in combination with the bisazo pigment, and as a result,
On the conductive substrate, the bisazo pigment represented by the general formula (1) is used as the charge generation material, and
(2):

[0016]

[Chemical 7]

(In the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different and are an alkyl group, an alkoxyl group, a halogen atom, an aryl group, a nitro group, a cyano group or an alkylamino group. (P and q represent integers of 0 to 3, and k, l, m and o represent integers of 0 to 2.)
A diamine compound represented by the following as a binder resin polycarbonate and the general formula (3):

[0018]

[Chemical 8]

(In the formula, one of A ³ and A ⁴ represents a divalent group containing at least an aromatic ring in the main chain, and the other is a divalent group containing no aromatic ring in the main chain. The electrophotographic photosensitive member provided with a photosensitive layer each containing a polyester having a repeating unit represented by the formula (1) has a high sensitivity and a high repeatability without impairing the excellent advantages of the bisazo pigment (1). The present invention has been completed by discovering a new fact that the characteristics can be exhibited.

That is, in the present invention, by combining the above-mentioned specific charge generating material, charge transporting material, and binder resin, it is stable against ozone and nitrogen oxides, as well as oxidative deterioration due to light, and is electrically conductive. Since it is possible to form a tough photosensitive layer having excellent adhesiveness to the base such as a substrate, the sensitivity and repetitiveness (durability) can be remarkably improved as compared with the conventional electrophotographic photoreceptor. The effect of the combination of the charge generating material, the charge transporting material, and the binder resin in the present invention is not necessarily clear, but the effect of suppressing oxidative deterioration caused by ozone, nitrogen oxides, etc. is considered as follows. ..

That is, the diamine-based compound (2) used as the charge transporting material has advanced delocalization of electrons and has a steric hindrance in which a nitrogen atom is surrounded by a phenyl group, so that the bisazo pigment (1 (3) is inhibited from being coordinated with the azo group, and therefore the electron density of the azo group is not increased, so that the polyester (3) is less likely to be attacked by the acid (acceptor) group or ozone. Further, as described later, the fact that the addition amount of the polyester (3) can be made smaller than that of the conventional one is considered to contribute to the suppression of the photooxidative deterioration of the azo group of the bisazo pigment (1).

In addition, the bisazo pigment (1) has a high charge generation efficiency and high sensitivity, and the diamine compound (2) has a bisazo pigment at an ionization potential.
Since it has a good relationship with (1) and has excellent light resistance and durability, and there is little difference in the electric field strength of the mobility, these characteristics are not reduced, and it becomes an optimum combination and becomes a combination of electrophotographic photoreceptors. It is believed that this has been achieved due to higher performance.

Further, the polyester (3) has a main chain which is softer than conventional ones, and the ester bond portion which contributes to the adhesiveness sufficiently acts on the underlayer. It can be improved sufficiently. Therefore, to improve the adhesiveness of the photosensitive layer made of polycarbonate having tough physical properties without lowering the sensitivity of the photoreceptor or promoting the photooxidative deterioration of the azo group of the bisazo pigment (1). You can

The bisazo pigment (1) and a diamine compound
(2) has a good relationship in terms of ionization potential, that is, the ionization potentials of both are approximate (the bisazo pigment (1) has an ionization potential of about 5.7 to 5.9 eV, and the diamine compound (2) has an ionization potential of 5.4 to 5.7 eV), and the charge injection from the bisazo pigment (1) to the diamine compound (2) during exposure is
A bisazo pigment in which there is no barrier and is easily performed, and the difference in ionization potential is within about 0.3 eV.
The combination of (1) and the diamine-based compound (2) improves the repeating characteristics. On the other hand, the case where the charge generation material and the charge transport material are not in a good relationship means that the difference in ionization potential is too large. For example, when the ionization potential of the charge generating material is considerably higher than that of the charge transporting material, the charge is easily injected from the charge generating material into the charge transporting material during charging (in the dark), so that the chargeability is deteriorated. Occurs. On the contrary, when the ionization potential of the charge transport material is considerably higher than the ionization potential of the charge generation material, it becomes difficult to inject charges especially in a low electric field, and the residual potential becomes large.

These facts will be clarified from the comparison between Examples and Comparative Examples described later.

[0026]

Preferred embodiments: In the bisazo pigment represented by the general formula (1), examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, Examples thereof include an alkyl group having 1 to 6 carbon atoms such as a hexyl group. Examples of the aryl group include a phenyl group, an o-terphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. Examples of the heterocyclic group include thienyl group, pyrrolyl group, pyrrolidinyl group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, 2H-imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyranyl group, pyridyl group. Group, piperidyl group, piperidino group, 3-morpholinyl group, morpholino group, thiazolyl group and the like. It may also be a heterocyclic group condensed with an aromatic ring.

Substituents which may be substituted on the above groups include
For example, a halogen atom, an amino group, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 2 to 2 carbon atoms. And the alkenyl group of 6 and the like. Examples of the coupler residue represented by A ¹ and A ² include groups represented by general formulas (a) to (g).

[0028]

[Chemical 9]

In each formula, R ³⁰ represents a carbamoyl group, a sulfamoyl group, an allofanoyl group, an oxamoyl group, an anthraniloyl group, a carbazoyl group, a glycyl group, a hydantoyl group, a phthalamoyl group, and a succinamoyl group. These groups, a halogen atom, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a nitro group, a cyano group, an alkyl group, an alkenyl group,
It may have a substituent such as a carbonyl group or a carboxyl group.

R ³¹ represents an atomic group necessary for forming an aromatic ring, a polycyclic hydrocarbon or a heterocyclic ring by condensing with R ³⁰ and the benzene ring having a hydroxyl group, and these rings are as described above. You may have the same substituent. R ³² represents an oxygen atom, a sulfur atom or an imino group. R ³³ represents a divalent chain hydrocarbon or aromatic hydrocarbon, and these groups may have the same substituents as described above.

R ³⁴ represents an alkyl group, an aralkyl group, an aryl group or a heterocyclic group, and these groups may have the same substituents as described above. R ³⁵ is a divalent chain hydrocarbon, an aromatic hydrocarbon, or the following formula (h) in the above general formulas (e) and (f):

[0032]

[Chemical 10]

It represents an atomic group necessary for forming a heterocycle with the moiety represented by, and these rings may have the same substituents as described above. R ³⁶ is a hydrogen atom, an alkyl group,
It represents an amino group, a carbamoyl group, a sulfamoyl group, an allofanoyl group, a carboxyl group, an ester of a carboxyl group, an aryl group, or a cyano group, and groups other than a hydrogen atom may have the same substituents as described above.

R ³⁷ represents an alkyl group or an aryl group, and these groups may have the same substituents as described above.
In R ³¹ , the atomic group necessary for forming an aromatic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group is, for example, a methylene group, an ethylene group, a propylene group,
Examples thereof include alkylene groups such as butylene group.

The aromatic ring formed by the condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group is
Examples thereof include naphthalene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, and naphthacene ring. In R ³¹ , the atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a polycyclic hydrocarbon is, for example, a methylene group, an ethylene group, a propylene group, a butylene group, or a carbon atom. Examples include alkylene groups of the numbers 1 to 4.

In R ³¹ , the polycyclic hydrocarbon condensed with R ³⁰ and the benzene ring having a hydroxyl group includes, for example, a carbazole ring, a benzocarbazole ring and a dibenzofuran ring. Further, in R ³¹ , the atomic group necessary for forming a heterocyclic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group is, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a 1H-indolyl group, a benzoyl group. Oxazolyl group, benzothiazolyl group, 1H-indazolyl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonilyl group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group Examples thereof include a xanthenyl group, an acridinyl group, a phenanthridinyl group, a phenazinyl group, a phenoxazinyl group and a thianthrenyl group.

The aromatic heterocyclic group formed by the condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group is, for example, a thienyl group, a furyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group or a thiazolyl group. , Isothiazolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group and thiazolyl group. In addition, it may be a heterocyclic group condensed with another aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group).

In R ³³ and R ³⁵ , examples of the divalent chain hydrocarbon include ethylene group, propylene group and butylene group, and examples of the divalent aromatic hydrocarbon include
Examples thereof include a phenylene group, a naphthylene group and a phenanthrylene group. Examples of the heterocyclic group for R ³⁴ include a pyridyl group, a pyrazyl group, a thienyl group, a pyranyl group and an indolyl group.

In R ³⁵ , the atomic group necessary for forming a heterocycle with the moiety represented by the formula (h) is, for example, phenylene group, naphthylene group, phenanthrylene group, ethylene group, propylene group, butylene. Examples include groups. Examples of the aromatic heterocyclic group formed by R ³⁵ and the portion represented by the formula (h) include, for example, benzimidazole group, benzo [f] benzimidazole group, dibenzo [e, g] benzimidazole group. Group, benzopyrimidine group and the like. These groups may have the same substituents as described above.

In the above R ³⁶ , examples of the carboxyl group ester include methyl ester, ethyl ester, propyl ester, butyl ester and the like. Coupler residue A represented by the above general formulas (a) to (g)
Specific examples of ¹ and A ² include the following groups.

[0041]

[Chemical 11]

[0042]

[Chemical formula 12]

[0043]

[Chemical 13]

[0044]

[Chemical 14]

Specific examples of the bisazo compound (1) include compounds represented by the following formulas (B1) to (B11).

[0046]

[Chemical 15]

[0047]

[Chemical 16]

[0048]

[Chemical 17]

In the diamine-based compound represented by the general formula (2), the alkyl group and the aryl group corresponding to R ^{2 to} R ⁷ in the formula are the same as those represented by the general formula (1). The ones are listed. Examples of the halogen atom include chlorine, iodine, bromine and fluorine.
Examples of the alkoxyl group include a methoxy group, an ethoxy group, an isopropoxy group, a butoxy group, a t-butoxy group,
A hexyloxy group and the like can be mentioned.

Examples of the alkylamino group include methylamino group, dimethylamino group, ethylamino group, diethylamino group, propylamino group, isopropylamino group, butylamino group, isobutylamino group, t-butylamino group, pentylamino group. , Hexylamino group and the like. As a specific compound of the diamine-based compound represented by the general formula (2), for example, the following formulas (A1) to (A13)
The compounds shown in are listed.

[0051]

[Chemical 18]

[0052]

[Chemical 19]

[0053]

[Chemical 20]

[0054]

[Chemical 21]

[0055]

[Chemical formula 22]

The diamine compound (2) can be synthesized by various methods. For example, the following general formula (40)
It can be produced by reacting the compound represented by and the compounds represented by the general formulas (41) to (44) simultaneously or sequentially.

[0057]

[Chemical formula 23]

(Wherein R ² , R ³ , R ⁴ , R ⁵ , R ⁶ ,
R ⁷ , k, l, m, o, p, and q are the same as above. X
Represents a halogen atom. ) The reaction between the compound represented by the general formula (40) and the compounds represented by the general formulas (41) to (44) is usually performed in an organic solvent,
As the solvent, any solvent can be used as long as it does not adversely affect this reaction, for example, nitrobenzene,
Examples of organic solvents include dichlorobenzene, quinoline, N, N-dimethylformamide, N-methylpyrrolidone, and dimethylsulfoxide. The reaction is usually carried out in the presence of a catalyst such as copper powder, copper oxide, copper halide, etc., and a basic substance such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, etc. It is carried out at a temperature of 250 ° C.

Further, the compound represented by the general formula (2) having a symmetric structure is controlled in the substitution position of the substituents R ² , R ³ , R ⁴ and R ⁵ , for example, the following general formula (45) ) By reacting a compound represented by the general formula (41) (43) with a compound represented by the following general formula (46), then the compound represented by the general formula (46) It can be produced by hydrolyzing and deacylating to obtain a compound represented by the following general formula (47), and further reacting it with a compound represented by the general formulas (42) and (44).

[0060]

[Chemical formula 24]

(In the formula, R ⁸ and R ⁹ represent an alkyl group, and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , k, l,
m, o, p, and q are the same as above. ) The reaction of the compound represented by the general formula (45) with the compound represented by the general formula (41) (43) is carried out by reacting the compound represented by the general formula (40) with the general formula (41) (42). ) (43) (44) can be carried out in the same manner as the reaction with the compound. The deacylation reaction of the compound represented by the general formula (46) by hydrolysis can be carried out by a conventional method in the presence of a basic catalyst. Further, the reaction between the compound represented by the general formula (47) and the compound represented by the general formula (42) (44), the compound represented by the general formula (40) and the general formula (41) ( It can be carried out in the same manner as the reaction with the compounds represented by 42) (43) (44).

After completion of the reaction, the reaction mixture was concentrated and reconstituted.
Crystals, solvent extraction, column chromatography, etc.
It can be easily separated and purified in stages. The general formula (3)
As described above, the polyester represented by³，
A^FourOne of which contains an aromatic ring in the main chain and the other
It must be free of aromatic rings in the chain. In the ceremony
Of A³, A^FourWhen both contain aromatic rings, the main chain becomes rigid.
Then, the effect of improving the adhesiveness due to the carbonyl group diminished.
End up. On the other hand, A³, A ^FourBoth do not contain aromatic rings
, A homogeneous photosensitive layer that is not compatible with polycarbonate
Can't get

When the divalent group containing no aromatic ring in the main chain contains an aliphatic group, the aliphatic group is a saturated aliphatic group containing no double bond or triple bond in the main chain. Is preferred. When the aliphatic group contains a double bond or a triple bond in the main chain, the rigidity of the main chain is slightly increased, so that the effect of improving the adhesiveness by the carbonyl group may be diminished.

The main chain end of the general formula (3) has a --OH group or a --COOH group, and it is preferable that the acid value showing the amount of the --COOH group is 2 (KOHmg / g) or less. When the acid value is much higher than 2, the adhesion of the photosensitive layer to the conductive substrate is improved, but the resistance value of the photosensitive layer is increased by forming a complex with the diamine compound (2) which is an electron donating compound. And the charging ability may be deteriorated.
Further, the —COOH group may act as an ion trap for cation radicals to hinder charge transport, resulting in reduced sensitivity.

The polyester (3) is not particularly limited, but preferably has a number average molecular weight of 10,000 to 50,000 or a glass transition temperature Tg of 15 ° C. or higher. When the number average molecular weight is less than 10,000, the glass transition temperature Tg is lowered, and the glass transition temperature Tg is 15
If the temperature falls below ° C, the film strength of the photosensitive layer may decrease. Further, when the number average molecular weight is much higher than 50,000, the number of -OH groups and -COOH groups at the molecular ends decreases,
This causes a decrease in adhesion.

The polyester (3) can be obtained by reacting the acid component represented by the general formula (3a) with the diol component represented by the general formula (3b).

[0067]

[Chemical 25]

Examples of the acid component include the following formulas (50) to
Examples thereof include compounds represented by (54).

[0069]

[Chemical formula 26]

Further, examples of the diol component include compounds represented by the following formulas (55) to (61).

[0071]

[Chemical 27]

Of these acid components and diol components, one of A ³ and A ^{4 in} the general formula (3) contains an aromatic ring in the main chain, and the other contains an aromatic ring in the main chain. It is used in combination as appropriate so that it does not exist. Further, as the acid component and the diol component, two or more kinds represented by the above formulas may be mixed and used. Polyester (3)
The ratio of the acid component and the diol component, which are raw materials of, of those containing an aromatic ring in the main chain is not particularly limited, but is 40-
About 80 mol% is preferable.

Specific examples of the polyester (3) include compounds (J1) to (J5) shown in Table 1 below.

[0074]

[Table 1]

In the above table, (53) u = 2 in the acid component column is succinic acid in which u is 2 in the formula (53), and (53) u = 4 is adipic acid in which u is 4. , (53) u = 7 represents azelaic acid in which u is 7. (55) v = 2 in the column of diol component is the above formula
(55) shows ethylene glycol in which v is 2. Among polycarbonate and polyester (3) as the binder resin, the content ratio of polyester (3) is preferably 0.5 to 50% by weight. When the content of the polyester (3) is less than 0.5% by weight, the adhesiveness of the photosensitive layer may not be sufficiently improved. When the content of the polyester (3) is much higher than 50% by weight, the polyester molecule may be added as described above. There is a possibility that the polar group in the carrier may become a carrier trap to reduce the sensitivity of the photoconductor, or may accelerate the photooxidative deterioration of the charge generating material and the charge transporting material under a high electric field.
In addition, as the content ratio of the polycarbonate decreases, the strength decreases, and there is a possibility that a tough photosensitive layer excellent in scratch resistance cannot be obtained.

As the polycarbonate to be used as the binder resin together with the polyester (3), various conventionally known ones can be used. In particular, the following general formulas (4), (5) and (6)
:

[0077]

[Chemical 28]

(Where R³⁸And R²⁰Are the same or different
Represents a hydrogen atom, an aliphatic group or an aromatic group, and an aliphatic group
And the aromatic group may have a substituent. Also R³⁸
And R³⁹May combine with each other to form a ring.
R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴, R ⁴⁵, R⁴⁶And R⁴⁷
Are the same or different and are hydrogen atom, halogen atom, aliphatic
Group or aromatic group is shown, and aliphatic group and aromatic group are
It may have a substituent. R ⁴⁸And R⁴⁹Is a hydrogen atom,
A halogen atom, an alkyl group and an aryl group are shown.
The alkyl group and the aryl group may have a substituent.
Yes. s and t are

[0079]

[Equation 2]

The number of is shown. At least one kind of the compounds having a repeating unit represented by any of (1) to (4) is preferably used. Examples of the aliphatic group in each of the above formulas include the same alkyl groups and alkoxy groups as described above, and examples of the aromatic group include the same aryl groups as described above and aralkyl groups such as a benzyl group. These groups may have the same substituents as described above.

Specific examples of the polycarbonate represented by the general formula (4) include compounds having repeating units (K1) to (K3) below.

[0082]

[Chemical 29]

Specific examples of the polycarbonate represented by the general formula (5) include compounds having the following repeating unit (K4).

[0084]

[Chemical 30]

(Where s and t are

[0086]

[Equation 3]

It is Further, specific compounds of the polycarbonate represented by the general formula (6) include, for example, compounds having the following repeating units (K5) to (K7).

[0088]

[Chemical 31]

The photoconductor of the present invention can be applied to either a single layer type or a laminated type as a photosensitive layer. However, the effect of the combination of the charge generating material, the charge transporting material, and the binder resin becomes more remarkable particularly in a single-layer type photosensitive layer in which each material is contained in the same layer. It can be said that it is more preferable to apply it to an electrophotographic photoreceptor provided with a mold type photosensitive layer.

In order to obtain a single-layer type photoreceptor, the bisazo pigment (1) which is a charge generating material, the diamine compound (2) which is a charge transporting material, and the polycarbonate and polyester ( 3) and the like may be formed on the conductive substrate by a means such as coating. Further, in order to obtain a laminated type photoreceptor, a charge generation layer containing the bisazo pigment (1) and a binder resin is formed on a conductive substrate by means such as vapor deposition or coating, and this charge generation layer is formed. A charge transport layer containing the diamine compound (2) and a binder resin may be formed thereon. Also, contrary to the above,
The charge transport layer may be formed on the conductive substrate, and then the charge generation layer may be formed. In the case of a laminated type, it is more preferable that the binder resin for both the upper and lower layers is composed of polycarbonate and polyester (3) in order to form a photosensitive layer that is tough and has excellent adhesiveness, but either layer May be composed only of polycarbonate and polyester (3).

As the charge generating material, in addition to the bisazo pigment (1), for the purpose of expanding the sensitivity region of the electrophotographic photosensitive member so as to have an absorption wavelength region in a desired region,
Further, other conventionally known charge generating materials can be used together. Other charge generating materials include selenium and selenium-
Tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo pigments other than those represented by the general formula (1), perylene pigments, anthanthrone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments. Examples thereof include pigments, threnic pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments and dithioketopyrrolopyrrole pigments.

The diamine-based compound that is a charge transport material
(2) can be used alone or in combination with other conventionally known charge transport materials. As the conventionally known charge transport material, various electron-withdrawing compounds and electron-donating compounds can be used. As the electron-withdrawing compounds, such as ^{2,6-dimethyl-2,, 6,} - di te
Diphenoquinone derivatives such as rt-dibutyldiphenoquinone, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone,
Examples include fluorenone compounds such as 3,4,5,7-tetranitro-9-fluorenone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride and dibromomaleic anhydride. It

As the electron-donating compound, 2,5
-Oxadiazole compounds such as di (4-methylaminophenyl) and 1,3,4-oxadiazole, 9- (4
-Styryl compounds such as diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indole Compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds,
Examples thereof include nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds, and triazole compounds, and condensed polycyclic compounds.

These charge transport materials may be used alone or in combination of two or more. When a charge transporting material having film-forming property such as polyvinylcarbazole is used,
In the case of the laminated type, the binder resin for the charge transport layer is not always necessary. As the binder resin, in addition to the above-mentioned polycarbonate and polyester (3), various resins can be used in combination as long as the strength and adhesiveness of the photosensitive layer are not impaired. For example, styrene polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-
Maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester alkyd resin, polyamide, Thermoplastic resin such as polyurethane, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, and other crosslinkable thermosetting resin Examples of the resin include photo-curable resins such as epoxy acrylate and urethane-acrylate. These binder resins may be used alone or in combination of two or more.

The single-layer type organic photosensitive layer and the laminated type organic photosensitive layer include
A sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and an additive such as a plasticizer can be contained. Further, in order to improve the sensitivity of the charge generation layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generation material.

In the laminated photoreceptor, the charge generating material and the binder resin constituting the charge generating layer can be used in various ratios, but the charge generating material 5 to 5 parts by weight relative to 100 parts by weight of the binder resin. It is preferably used in an amount of 1000 parts by weight, particularly 30 to 500 parts by weight. The charge transport material constituting the charge transport layer and the binder resin can be used in various proportions within a range that does not inhibit charge transport and a range that does not crystallize. 10 to 500 parts by weight of the charge transport material, particularly 25 to 100 parts by weight of the binder resin so that the charges can be easily transported.
It is preferably used in a proportion of 200 parts by weight.

The thickness of the laminated photosensitive layer is preferably 0.01 to 5 μm, particularly 0.1 to 3 μm for the charge generation layer, and 2 to 100 μm for the charge transport layer.
m, particularly preferably about 5 to 50 μm.
In a single-layer type photoreceptor, the charge generation material is 0.1 to 50 parts by weight, particularly 0.5 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
30 parts by weight, 20 to 500 parts by weight, especially 30 to 200 parts by weight of the charge transport material are suitable. The thickness of the single-layer type photosensitive layer is 5 to 100 μm, particularly 10 to 50 μm.
It is preferable that the thickness is about m.

In the case of a single-layer type photoreceptor, it is between a conductive substrate and a photosensitive layer, and in the case of a laminated type photoreceptor, it is between a conductive substrate and a charge generation layer, and a conductive substrate. A barrier layer may be formed between the charge transport layer and the charge transport layer or between the charge generation layer and the charge transport layer to the extent that the characteristics of the photoreceptor are not impaired. It may be formed.

As the conductive substrate on which the above layers are formed, various conductive materials can be used.
For example, metals such as aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, and plastic materials in which the above metals are vapor-deposited or laminated, iodide Examples thereof include glass coated with aluminum, tin oxide, indium oxide and the like.

The conductive substrate may be in the form of a sheet, a drum or the like, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. Further, the conductive substrate is preferably one having sufficient mechanical strength when used. When each of the above layers is formed by a coating method, the charge generating material, charge transporting material, binder resin and the like exemplified above are combined with a suitable solvent by a known method, for example, a roll mill, a ball mill, an attritor, a paint shaker. Alternatively, an ultrasonic disperser or the like may be used for dispersion and mixing to prepare a coating solution, which may be coated and dried by a known means.

As the solvent for preparing the coating solution, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol, butanol,
Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether and tetrahydrofuran. , Ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formaldehyde, dimethyl formamide and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport material or the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent, etc. may be used.

[0103]

The present invention will be described in detail below with reference to Examples and Comparative Examples. Examples 1 to 11 and Comparative Examples 1 to 6 (single-layer type photoreceptors) The following components were dispersed in a paint shaker for 2 hours, and then 10 parts by weight of polycarbonate and polyester as a binder resin were added to 40 parts by weight of dichloromethane. The solution dissolved in was added and dispersed for 1 hour to prepare a coating liquid for a single-layer type photosensitive layer. Then, the surface of an aluminum cylinder is coated with this coating solution by a dip coating method, and 1
It was dried at 00 ° C. for 30 minutes to form a single-layer type photosensitive layer having a film thickness of 25 μm to obtain a positive charging type single-layer type electrophotographic photosensitive member.
The specific compounds of the bisazo pigments, diamine compounds, polycarbonates and polyesters used are shown in Table 2 by using the compound numbers of the above specific examples.

(Component) (Parts by Weight) Bisazo Pigment (Charge Generating Material) 2 Diamine Compound (Charge Transporting Material) 8 Diphenoquinone Derivative 2 Dichloromethane 70 As the diphenoquinone derivative, TPDQ represented by the following formula was used.

[0105]

[Chemical 32]

[0106]

[Table 2]

In the above table, the symbols used in Comparative Examples 3 to 6 (J
The polyesters 6) to (J9) are compounds shown in Table 3 below. The symbols of the acid component and the diol component in Table 3 indicate the same compounds as described above.

[0108]

[Table 3]

Examples 12 to 16 and Comparative Examples 7 and 8 (laminated type)
(Photoreceptor) 1 part by weight of bisazo pigment and 40 parts by weight of cyclohexanone were dispersed in a paint shaker for 2 hours, and then 10% cyclohexanone solution of vinyl chloride-vinyl acetate copolymer 2
0 part by weight was added and the mixture was further dispersed for 2 hours. The obtained dispersion was applied onto an aluminum cylinder and dried to give a film thickness of 0.
A 5 μm charge generation layer was formed.

A solution of a composition for a charge generating layer having the following composition was applied onto this charge generating layer by a dip coating method, and 1
By drying at 00 ° C. for 1 hour, a charge transport layer having a film thickness of 23 μm was formed to obtain a negative charging type electrophotographic photosensitive member. Specific compounds of the bisazo pigments, diamine compounds, polycarbonates and polyesters used are shown in Table 4 by using the compound numbers of the above specific examples.

(Component) (Parts by Weight) Diamine compound (charge transport material) 80 Diphenoquinone derivative (TPDQ) 20 Binder resin 100 Dichloromethane 400

[0112]

[Table 4]

The following tests were carried out on the electrophotographic photoreceptors of the above-mentioned respective Examples and Comparative Examples, and their characteristics were evaluated. Electrical Properties The electrophotographic photoconductors prepared in each of the examples and comparative examples were set in a drum sensitivity tester, the surface potential (V) when the surface was charged to around ± 800 V was measured, and then the photoconductor for PPC. The half-exposure amount was measured using the light of 550 nm, which is the most necessary. That is, the light with a wavelength of 550 nm extracted from a xenon lamp using a spectroscope has an intensity of 0.3.
Exposure was performed at mW / cm ² and an exposure time of 1 second, and the half-exposure amount (μJ / cm ² ) was determined. In addition, 0.5 immediately after exposure
The surface potential after a lapse of seconds was determined as the post-exposure potential (V). Repetitive characteristics Surface potential (V), half-exposure amount (μJ / cm ² ), post-exposure potential (V) after repeating copying 50,000 times with electrostatic copying machine DC-1670M (manufactured by Mita Kogyo Co., Ltd.) Was measured. Adhesiveness Adhesiveness of the photosensitive layer was evaluated according to the cross-cut test described in JIS K 5400 "General Test Method for Paints".

The above test results are shown in Tables 5 to 7.

[0115]

[Table 5]

[0116]

[Table 6]

[0117]

[Table 7]

As is clear from these tables, Comparative Example 1 containing no polyester has a significantly low adhesiveness. Further, in Comparative Example 2 in which the content of the polyester was much higher than 50% by weight, the strength of the photosensitive layer was insufficient, and the continuous blade was dented in the cleaning blade pressure contact portion, and an image defect occurred from around 5,000 sheets. It was not possible to perform the measurement after continuously copying ten thousand sheets.

Comparative Example 3 using the polyester of (J6) in which both A ³ and A ⁴ in the general formula (3) contain an aromatic ring.
Has a low adhesiveness and peeled off the photosensitive layer from the developing seal portion after about 18,000 sheets, and the measurement after continuous copying of 50,000 sheets could not be performed. Comparative Example 7 using the same polyester (J6) also has low adhesiveness and peeling occurs at the interface between the charge generation layer and the charge transport layer after about 30,000 sheets, and measurement should be performed after 50,000 sheets are continuously copied. I couldn't.

In Comparative Examples 4 and 5 in which the polyesters (J7) and (J8) in which both A ³ and A ⁴ in the general formula (3) do not contain an aromatic ring were used, the polyester and the polycarbonate were compatible with each other. No, a uniform photosensitive layer could not be formed, and each of the above tests could not be performed. Acid number significantly exceeds 2 (J9)
Although Comparative Examples 6 and 8 using the polyester of No. 1 have excellent adhesiveness, the surface potential after continuous copying of 50,000 sheets was remarkably lowered and the half-exposure amount was remarkably increased.

On the other hand, all the photoconductors of the respective examples had good adhesiveness and high sensitivity, and a clear image was obtained even at a normal exposure intensity, and a good image was obtained by repeated copying.

[0122]

According to the present invention, a bisazo pigment represented by the general formula (1) which is a charge generating material is selected, and a diamine compound represented by the general formula (2) is used as a charge transport material. By combining polycarbonate with polyester (3) as a binder resin, an organic photoreceptor having extremely excellent electrophotographic characteristics, which has never been obtained, can be obtained.

Claims (5)

[Claims] 1. A general formula (1) as a charge generating material on a conductive substrate: (In the formula, A ¹ and A ² are the same or different and each represents a coupler residue, R ¹ represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, and the alkyl group, the aryl group and the heterocyclic group represent A bisazo pigment represented by the formula (2): which may have a substituent, n represents 0 or 1, is used as a charge transport material. (In the formula, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different and represent an alkyl group, an alkoxyl group, a halogen atom, an aryl group, a nitro group, a cyano group or an alkylamino group. p and q represent an integer of 0 to 3. k,
l, m and o represent an integer of 0-2. ), A diamine compound represented by the formula (1) is used as a binder resin of polycarbonate and a compound represented by the general formula (3): (In the formula, one of A ³ and A ⁴ represents a divalent group containing at least an aromatic ring in the main chain, and the other represents a divalent group containing no aromatic ring in the main chain. An electrophotographic photosensitive member is provided with a photosensitive layer each containing a polyester having a repeating unit represented by. 2. The electrophotographic photosensitive member according to claim 1, wherein the polyester represented by the general formula (3) has an acid value of 2 (KOHmg / g) or less. 3. The acid component represented by the general formula (3a) and the diol component represented by the general formula (3b), which are the raw materials of the polyester represented by the general formula (3), are mainly contained. The ratio of the component containing an aromatic ring in the chain is 40 to 80 mol%.
The electrophotographic photosensitive member described. [Chemical 4] 4. The electrophotographic photosensitive member according to claim 1, wherein the content of the polyester is 0.5 to 50% by weight of the polycarbonate as the binder resin and the polyester represented by the general formula (3). 5. Polycarbonate is represented by the general formula (4) (5) and
(6): [Chemical 5](R in the formula³⁸And R²⁰Are the same or different hydrogen atoms,
Indicates an aliphatic group or an aromatic group, an aliphatic group and an aromatic group
The group may have a substituent. Also R³⁸And R³⁹Is
They may combine with each other to form a ring. R⁴⁰, R⁴¹，
R⁴², R⁴³, R⁴⁴, R ⁴⁵, R⁴⁶And R⁴⁷Are the same or
Differently hydrogen atom, halogen atom, aliphatic group or aromatic
Group is represented by aliphatic group and aromatic group have a substituent
You may stay. R ⁴⁸And R⁴⁹Is hydrogen atom, halogen atom
Child, an alkyl group and an aryl group are shown.
And the aryl group may have a substituent. s and
t is the followingIndicates the number of ) Has a repeating unit represented by
The compound according to claim 1, which is at least one of the following compounds:
Child photoconductor.