JPH0962018A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor usable in a positive electrification system and excellent in characteristics. SOLUTION: The photosensitive layer 4, 14 of this electrophotographic photoreceptor with the layer 4, 14 on the electrically conductive substrate 3, 13 contains a diphenoquinone compd. represented by the formula (where X is halogen, cyano or nitro, each of R1 -R3 is satd. hydrocarbon and R1 -R3 may be different from one another) as an electric charge transferring agent. Since the compd. has an electron withdrawing group, a high degree of electron transfer is ensured, and the compd. has satisfactory compatibility with a resin binder because of its completely asymmetric structure. In the case where all of R1 -R3 in the formula are tert-butyl groups and X is Cl, the compd. is easily produced and has satisfactory compatibility with a disazo pigment or oxytitanyl phthalocyanine as an electric charge generating material.

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 a copying machine, a laser printer or the like, and particularly to an electrophotographic photosensitive member using an organic thin film.

[0002]

2. Description of the Related Art Conventionally, a thin film made of a material such as selenium, selenium-tellurium, selenium-arsenic, and amorphous silicon has been used as a photosensitive layer in an electrophotographic photosensitive member used in a copying machine, a laser printer or the like. Was there.

However, in recent years, those using organic photoconductors which are low in price and have little environmental pollution are becoming mainstream. Such organic photoreceptors can be classified into a single-layer dispersion type photosensitive layer and a function separation type photosensitive layer when classified by the structure of the photosensitive layer.

The single-layer dispersion type photoconductor is one in which a charge generating substance is dispersed in a medium of a charge transfer substance and both functions are provided by a single layer film, and the function separation type photoconductor generates charges. The charge generation layer (CGL) for causing the charge generation and the charge transfer layer (CTL) for moving the generated charges are separately formed. At present, any type of electrophotographic photoreceptor is put to practical use, but in order to improve sensitivity, development of a charge transfer substance having high mobility is desired.

On the other hand, when the organic photoconductor is classified by the charge type,
There are two types of charge transfer materials, positive charge type and negative charge type. Among the currently known charge transfer substances, most of them have high mobility, and most of them have hole mobility. The mainstream of the photoreceptor is the negative charging type.

By the way, generally, a corona discharge phenomenon is used to negatively charge an electrophotographic photosensitive member.
Due to the generation of a large amount of ozone due to the discharge, various inconveniences have occurred such as polluting the indoor environment and accelerating the deterioration of the electrophotographic photosensitive member.

Therefore, although improvements such as adding a filter for capturing ozone have been made, there has been a problem that the device becomes complicated and large. On the other hand, it has been attempted to adopt a special charging method that does not generate ozone, but new problems such as a complicated electrophotographic process have occurred.

In order to solve such a situation, a positively charged type electrophotographic photoconductor which generates less ozone is required in the recent market, and for that purpose, it is necessary to develop an electron transfer substance having high mobility. Become.

However, despite energetic research,
At present, trinitrofluorenone (TN) is used as an electron transfer material that can be used for positively charged photoreceptors.
F), tetracyanoethylene, tetracyanoquinodimethane (TCNQ), quinone, diphenoquinone, naphthoquinone, anthraquinone, and derivatives thereof have been found only to have insufficient properties. Specifically, these electron transfer materials have the following drawbacks.

Most of these electron transfer substances have poor compatibility with the binder resin and cannot be uniformly dispersed in the photosensitive layer at a high concentration, so that the electrical characteristics cannot be satisfied due to insufficient content. . TNF has a high electron-accepting property and therefore a high mobility, but is not suitable for practical use because of its high toxicity. TCNQ has an extremely high electron-accepting property, but since it is strongly colored, when the photosensitive layer is formed, it absorbs light that should originally reach the charge-generating substance, which lowers the sensitivity. In the diphenoquinone skeleton, an asymmetric substitution type compound has been proposed in order to improve the compatibility, but a compound having sufficient performance for producing a highly sensitive positive charging type electrophotographic photoreceptor has not been obtained.

As described above, at present, no electron transfer substance for realizing a positively charged type electrophotographic photosensitive member has been practically used.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide an electrophotographic photoreceptor having excellent characteristics which can be used in the positive charging system. .

[0013]

In order to solve the above-mentioned problems, the invention according to claim 1 is an electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the following general structure. Formula (1),

[0014]

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(In the general formula (1), X represents one of halogen, cyano group and nitro group.
R ₁ , R ₂ and R ₃ are saturated hydrocarbons and may be the same or different from each other. ) Is contained as a charge transfer substance, a diphenoquinone compound represented by

The invention according to claim 2 is the electrophotographic photoreceptor according to claim 1, wherein X of the diphenoquinone compound represented by the general formula (1) is chlorine (Cl),

The invention according to claim 3 is the electrophotographic photoreceptor according to claim 1 or 2, wherein R ₁ and R of the diphenoquinone compound represented by the general formula (1) are Both of ₂ and R ₃ are tert-butyl groups,

The invention according to claim 4 is the electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the charge generating substance used in the photosensitive layer is a disazo pigment or oxytitanyl. Characterized by containing at least one of phthalocyanines,

The invention according to claim 5 is the electrophotographic photoreceptor according to claim 3 or 4, wherein the diphenoquinone compound is represented by the following chemical formula (2):

[0020]

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A diphenoquinone compound represented by the formula (2) is represented by the following chemical formula (3):

[0022]

[Chemical 6]

H in a liquid in which the compound represented by
According to the above-mentioned constitution of the present invention, which is characterized by being synthesized by contacting with Cl gas, the diphenoquinone compound represented by the general formula (1) has a halogen, a cyano group, or a halogen atom in which X is an electron-withdrawing group, or Since it is a nitro group, it has a high electron accepting property and a high mobility.

It has been conventionally performed that such a substituent of the electron transfer substance is used as an electron withdrawing group, but a compound containing the electron withdrawing group is known to increase the cohesive force of the electron transfer substance itself. The electron transfer material has poor compatibility with the binder resin, and therefore cannot be dispersed in the photosensitive layer at a high concentration, which is not practical.

In order to improve the compatibility, it is generally said that the electron transfer material should have an asymmetric structure. In the prior art, for example, the electron transfer material having an asymmetric structure is produced by the following synthesis method. Has been.

[0026]

[Chemical 7]

(Me represents a methyl group.) However, the following chemical formula (1
1),

[0028]

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The electron transfer material (2) has two identical substituents, does not have a completely asymmetric structure, and has a low electron mobility.

When an electron withdrawing group is introduced into such an electron transfer substance having an incomplete asymmetric structure to improve the electron mobility, the compatibility obtained in the asymmetric structure is introduced into the electron withdrawing group. Will be canceled by. For example,
The known electron transfer material represented by the following chemical formula (12) is not practical because it dissolves only a few percent in the binder resin.

[0031]

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As a result of earnest studies by the present inventors, particularly when the diphenoquinone compound has a completely asymmetric structure having no axis of symmetry, the compatibility with the binder resin is good even when an electron-withdrawing group is introduced. I found a thing. That is, the diphenoquinone compound has the structure of the above general formula (1).

Specifically, X is an electron-withdrawing group such as a halogen, a cyano group or a nitro group, and R ₁ , R ₂ , R
_{When 3} is a saturated hydrocarbon and is the same or different from each other, the diphenoquinone compound represented by the general formula (1) has high electron mobility and good compatibility with the binder resin. When used as an electron transfer material, a highly sensitive electrophotographic photoreceptor can be obtained by uniformly dispersing it in a photosensitive layer at a high concentration.

Specific examples of the saturated hydrocarbon group represented by the substituents R ₁ , R ₂ and R ₃ include linear saturated hydrocarbon groups such as methyl group, ethyl group and propyl group, and Isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, t
ert-Branched saturated hydrocarbon group such as pentyl group, cyclic saturated hydrocarbon group such as cyclopropyl group, cyclobutyl group, cyclopentyl group and cyclohexyl group, and composites of these linear, branched and cyclic saturated hydrocarbon groups It can be used without any limitation on the number of carbon atoms or the structure thereof such as a substituent.

Particularly, when X is chlorine, the production is easy, and the electrophotographic photosensitive member can be produced at a low cost.

Further, if R _{1 to} R ₃ are tert-butyl groups, the following chemical formula (3)

[0037]

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By bringing HCl gas into contact with a liquid in which the compound represented by the following formula is uniformly dissolved, the following chemical formula (2),

[0039]

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A completely asymmetric diphenoquinone compound represented by can be synthesized. Such a simple and high-yield synthetic method has not been heretofore known.

It should be noted that an electron transfer substance effective for a specific charge generating substance is not necessarily effective for another charge generating substance, and conversely effective for a specific electron generating substance. It is known that such a charge generating substance is not always effective for other electron transfer substances, and that a compatibility exists.

The diphenoquinone compound represented by the general formula (1) has a good compatibility especially when a disazo pigment or oxytitanyl phthalocyanine is used as the charge generating substance.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION <Production Example 1> An example of a method for producing the diphenoquinone compound represented by the general formula (1) used in the present invention will be described.

First, 91.8 g of potassium permanganate was added to a solution of 30.0 g of 2,6-di-tert-butylphenol in 300 ml of chloroform, and the temperature was adjusted to 5
The mixture was kept at 5 to 60 ° C and stirred for 25 hours. Then, the inorganic substances were separated by filtration, concentrated and then filtered, and the obtained residue was dissolved in 100 ml of chloroform and recrystallized by adding a small amount of methanol to give reddish brown crystals having a melting point of 242-2.
Diphenoquinone at 43 ° C. was obtained. The weight was measured and found to be 21.5 g, which was 72% when converted into a yield.

Next, 300 ml of acetic acid and 12 ml of chloroform
0 ml of a mixed solution was prepared, and 3.0 g of the red-brown crystal diphenoquinone was dissolved using the solution as a reaction solvent, kept at room temperature in a nitrogen atmosphere, blown with HCl gas, and reacted with stirring.

After blowing the HCl gas for 7 hours, the mixture was stirred overnight at room temperature, and the precipitate was filtered off. The filtrate was concentrated under reduced pressure, 300 ml of water was added, and the mixture was filtered to obtain 3.8 g of a yellow solid precipitate. This 3.8g
The yellow solid precipitate was dissolved in 25 ml of methanol, and a small amount of water was added for recrystallization to obtain 2.4 g of diphenol having a melting point of 150 to 151 ° C. as pale yellow crystals.
It was 84% when converted into a yield.

The above-mentioned 2.4 g of diphenol was dissolved in 180 ml of chloroform, 28.0 g of lead dioxide was added, the mixture was stirred at room temperature for 3 hours, and the residue was filtered off. After concentrating the filtrate, 20 ml of methanol was added. The precipitated crystals were filtered and washed with methanol to obtain 1.9 g of diphenoquinone represented by the above chemical formula (2) having a melting point of 155 to 156 ° C as reddish purple crystals. 8 when converted to yield
It was 1%. The above reaction process is shown below.

[0048]

[Chemical 12]

The above chemical formulas used in Examples 1-6 below.
The diphenoquinone compound represented by (3) is synthesized by the production method of <Production Example 1>.

Example 1 An example of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. Referring to FIG. 1A, reference numeral 2 denotes a single-layer dispersion type electrophotographic photosensitive member according to an embodiment of the present invention, which is a conductive substrate 3 made of a single cylindrical aluminum tube, and the conductive substrate. 3 and a photosensitive layer 4 formed on it.

The method of forming the photosensitive layer 4 will be described. First, with respect to 10 parts by weight of polycarbonate as a binder resin, the following chemical formula (4),

[0052]

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1 part by weight of a disazo pigment, which is a charge generating substance, and THF (tetrahydrofuran), which is a solvent
80 parts by weight were kneaded and dispersed by a sand mill for 10 hours. Then, the following chemical formula (5),

[0054]

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TPD (triphenyldiamine) represented by
Using a solution in which 9 parts by weight of the derivative and 1 part by weight of the diphenoquinone compound of the chemical formula (2) are dissolved, a thin film having a thickness of 20 μm is coated on the conductive substrate 3 by a dipping method, and the temperature is set to 80 ° C. And dried for 1 hour to form the photosensitive layer 4.
(The photosensitive layer 4 serves as both the charge generation layer and the charge transfer layer).

Comparative Example 1 _{1 In} the same electrophotographic photosensitive member as in Example 1, the following chemical formula (3) was used instead of the diphenoquinone of the chemical formula (2).

[0057]

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A photosensitive layer was formed using diphenoquinone represented by:

(Comparative Example 1 ₂ ) In the same electrophotographic photoreceptor as in Example 1, the following chemical formula (11) was used instead of the diphenoquinone of the chemical formula (2).

[0060]

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A photosensitive layer was formed using diphenoquinone represented by:

(Measurement condition A) A corona discharger was set so that the corona discharge current was 17 μA, and corona discharge was performed on the electrophotographic photosensitive members of Example 1 and Comparative Examples 1 ₁ and 1 _{2 in} a dark place. Was carried out and positively charged. Then, the surface potential of each electrophotographic photosensitive member is exposed to white light to reduce the surface potential from 700 V to 350 V by half (exposure energy: half exposure energy: lux x s
ec) was measured. The half-exposure energy is a value indicating the sensitivity of the electrophotographic photosensitive member.

(Measurement Result 1) The above Example 1 and Comparative Example 1 ₁ ,
The measurement results of 1 ₂ are as shown in Table 1 below.

[0064]

[Table 1]

Both Example 1 and Comparative Examples 1 ₁ and 1 ₂ are single-layer dispersion positive charging type electrophotographic photoconductors using the disazo pigment of the chemical formula (4) as a charge generating substance. example 1, the comparative examples 1 _1, 1 ₂ significantly higher sensitivity than the case of using the diphenoquinone compound of formula (2) as an electron transfer material, a good charge generating substance and a compatibility disazo I understand.

Example 2 This example 2 is a single-layer dispersion type electrophotographic photosensitive member using oxytitanyl phthalocyanine instead of disazo pigment as a charge generating substance.
In order to form the photosensitive layer 4 shown in FIG. 1 (a), first, 1 part by weight of high-purity oxytitanyl phthalocyanine (charge generating substance), 10 parts by weight of polycarbonate (binder),
80 parts by weight of THF (solvent) was kneaded and dispersed in a sand mill for 10 hours. Next, by using a liquid in which 9 parts by weight of the TPD derivative of the chemical formula (5) and 1 part by weight of the diphenoquinone of the chemical formula (2) are dissolved, the conductive substrate 3
A thin film having a film thickness of 20 μm was applied on the film and dried at 80 ° C. for 1 hour to form the photosensitive layer 4.

Comparative Example 2 _{1 In} the same electrophotographic photoreceptor as in Example 2, a photosensitive layer was formed using the diphenoquinone represented by the chemical formula (3) instead of the diphenoquinone represented by the chemical formula (2).

Comparative Example 2 ₂ Similarly, a diphenoquinone represented by the chemical formula (11) was used to form a photosensitive layer in place of the diphenoquinone represented by the chemical formula (2).

(Measurement result 2) Half-exposure energy was measured under the same conditions (measurement condition A) as those measured in Table 1 above. The Example 2 shows the Comparative Example 2 _1, 2 ₂ of the measurement results are shown in Table 2 below.

[0070]

[Table 2]

The electrophotographic photoreceptors of Example 2 and Comparative Examples 2 ₁ and 2 ₂ are both single-layer dispersion positive charging type using oxytitanyl phthalocyanine as a charge generating substance. It can be seen that the electron transfer substance of the above chemical formula (2) has a higher sensitivity than those of Examples 2 ₁ and 2 ₂ and has good compatibility with oxytitanyl phthalocyanine which is a charge generating substance.

Example 3 Next, an example of the electrophotographic photosensitive member of the present invention having a photosensitive layer having a function-separated structure will be described.
Referring to FIG. 1 (b), reference numeral 12 is an example of the electrophotographic photosensitive member of the function-separated structure of the present invention, which has a conductive substrate 13 made of a cylindrical aluminum tube alone. A charge generation layer 15 and a charge transfer layer 16 are formed in this order on the conductive substrate 13, and the charge generation layer 15 and the charge transfer layer 16 form a photosensitive layer 14.

The method of forming the photosensitive layer 14 will be described below.
First, the charge generation layer 15 is obtained by dry-kneading 1 part by weight of polyvinyl butyral, which is a binder resin, and 2 parts by weight of the disazo pigment represented by the chemical formula (4) (charge generating substance), and then 1,4 by a sand mill. 16 parts by weight of dioxane and 4 parts by weight of acetone are kneaded and dispersed for 2 hours as a solvent, and then applied as a coating liquid on the conductive substrate 13 by dip coating.
It was dried to form a thin film having a thickness of 0.5 μm.

The charge transfer layer 16 is coated on the charge generation layer 15 by a dip coating method with 10 parts by weight of polycarbonate and 100 parts by weight of THF to 10 parts by weight of diphenoquinone represented by the chemical formula (2). Then, a thin film having a thickness of 20 μm was formed and dried at 80 ° C. for 1 hour.

Comparative Example 3 _{1 In} the same electrophotographic photosensitive member as in Example 3, a diphenoquinone represented by the chemical formula (3) was used to form a photosensitive layer in place of the diphenoquinone represented by the chemical formula (2). .

(Comparative Example 3 ₂ ) Similarly, instead of the diphenoquinone represented by the chemical formula (2) of Example 3, the chemical formula (1)
A photosensitive layer was formed using the diphenoquinone shown in 1).

(Measurement Result 3) Half-exposure energy was measured under the conditions shown in (Measurement condition A) above. The measurement results are shown in Table 3 below.

[0078]

[Table 3]

In both Example 3 and Comparative Examples 3 ₁ and 3 ₂ , the charge transfer layer is formed on the charge generating layer formed by disperse coating of the disazo pigment to form the photosensitive layer. But,
The Example 3 has a significantly higher sensitivity than the Comparative Examples 3 ₁ and 3 ₂ , and the electron transfer material represented by the chemical formula (2) is a charge generating material even when it has a function-separated structure. It turns out that it is compatible with the disazo pigment.

Example 4 In this example 4, a function-separated electrophotographic photosensitive member 12 having a photosensitive layer 14 formed by a vapor deposition method was manufactured. First, the electroconductive substrate 13 was made of an aluminum drum, and high-purity oxytitanyl phthalocyanine was vapor-deposited on the surface of the electroconductive substrate 13 at a pressure of 10 ⁻⁵ torr and a heating temperature of 500 ° C. to form a charge generation layer 15 having a film thickness of 500 Å.

Then, a coating solution comprising 10 parts by weight of polycarbonate and 100 parts by weight of THF was applied to 10 parts by weight of the diphenoquinone of the chemical formula (2) on the charge generation layer 15 by a dipping method to obtain a film thickness of 20 μm. Forming a thin film of
The charge transfer layer 16 was formed by drying at 0 ° C. for 1 hour.

Comparative Example 4 _{1 In} the electrophotographic photoreceptor 12 of Example 4, a diphenoquinone represented by the chemical formula (3) was used to form a photosensitive layer in place of the diphenoquinone represented by the chemical formula (2).

Comparative Example 4 ₂ Similarly, a diphenoquinone represented by the chemical formula (11) was used in place of the diphenoquinone represented by the chemical formula (2) to form a photosensitive layer.

(Measurement Result 4) Half-exposure energy was measured under the conditions shown in (Measurement condition A) above. The measurement results are shown in Table 4 below.

[0085]

[Table 4]

In Example 4 and Comparative Examples 4 ₁ and 4 ₂ , oxytitanyl phthalocyanine, which is a charge generating substance, is formed into a charge generating layer by vacuum deposition, and a charge transfer layer is formed thereon. However, Example 4 has a significantly higher sensitivity than Comparative Examples 4 ₁ and 4 ₂ , and the chemical formula
It can be seen that the electron transfer substance (2) has good compatibility with the charge generation layer of oxytitanyl phthalocyanine formed by the vapor deposition method.

Example 5 In this example, oxytitanyl phthalocyanine was formed into a film by a coating method to manufacture a function-separated electrophotographic photoreceptor 12. First, 5 g of high-purity oxytitanium phthalocyanine was dry ground with a paint shaker for 100 hours together with 50 ml of glass beads.
50 ml of propanol and 5 g of polyvinyl butyral were added, wet milling was carried out for 1 hour, and 100 ml of methyl ethyl ketone was further added and dispersed for 10 hours.

The solution obtained by this dispersion is dip-coated on a conductive substrate 13 made of an aluminum drum,
After drying, the charge generation layer 15 having a film thickness of 0.2 μm was formed.

On the charge generation layer 15, the chemical formula (2)
A solution of 10 parts by weight of polycarbonate and 100 parts by weight of THF is applied to 10 parts by weight of diphenoquinone represented by the above by a dipping method to form a thin film having a thickness of 20 μm.
The charge transfer layer 16 was formed by drying at 0 ° C. for 1 hour.

(Comparative Example 5 ₁ ) In the same function-separated electrophotographic photoreceptor as in Example 5, a diphenoquinone represented by the chemical formula (3) was used in place of the diphenoquinone represented by the chemical formula (2). Was formed.

(Comparative Example 5 ₂ ) Similarly, instead of the diphenoquinone represented by the chemical formula (2) of Example 5, the chemical formula (1)
A photosensitive layer was formed using the diphenoquinone shown in 1).

(Measurement Result 5) Half-exposure energy was measured under the conditions shown in the above measurement condition A. The measurement results are shown in Table 5 below.

[0093]

[Table 5]

In each of Example 5 and Comparative Examples 5 ₁ and 5 ₂ , the charge transfer layer was formed on the charge generation layer formed by coating after dispersion of oxytitanyl phthalocyanine, which is the charge generation substance. In Example 5, the electrophotographic photoconductors of Comparative Examples 5 ₁ and 5 ₂ are obviously higher in sensitivity, and the electron transfer material represented by the chemical formula (2) is oxytitanyl formed by dispersion coating. It can be seen that the compatibility with the phthalocyan thin film is good.

Example 6 In this example 6, a negative charging type function-separated electrophotographic photosensitive member 12 was manufactured. First, 2 parts by weight of the disazo pigment represented by the chemical formula (4) (charge generating substance) and 1 part by weight of polyvinyl butyral (binder) were dry-kneaded, and then 16 parts by weight of 1,4-dioxane and 4 parts by weight of acetone were added. A sand mill is used as a solvent to disperse the coating solution for 2 hours to prepare a coating solution, which is applied by dipping onto a conductive substrate 13 made of an aluminum drum and dried to a film thickness of 0.5.
A charge generation layer 15 of μm was formed.

TPD derivative 1 represented by the above chemical formula (5)
10 parts by weight of polycarbonate and THF against 0 parts by weight
A solution in which 100 parts by weight and 1 part by weight of diphenoquinone represented by the chemical formula (2) are dissolved is applied onto the charge generation layer 15 by a dipping method to form a thin film having a thickness of 20 μm. The charge transfer layer 16 was formed by drying at 0 ° C. for 1 hour.

Comparative Example 6 _{1 In} the same function-separated type electrophotographic photoreceptor as in Example 6, the diphenoquinone represented by the chemical formula (3) was used in place of the diphenoquinone represented by the chemical formula (2). Was formed.

(Comparative Example 6 ₂ ) Similarly, instead of the diphenoquinone represented by the chemical formula (2) of Example 6, the chemical formula (1)
A photosensitive layer was formed using the diphenoquinone shown in 1).

(Measurement Conditions B) The electrophotographic photosensitive members of Example 6 and Comparative Examples 6 ₁ and 6 ₂ were evaluated by the following measurements.
The corona discharge device was set so that the corona discharge current was 17 μA, and each electrophotographic photosensitive member was subjected to corona discharge in a dark place to be negatively charged, and then exposed to white light to have a surface potential of −.
The half-exposure energy (lux x sec) at which the voltage was halved from 700V to -350V was determined.

(Measurement Result 6) The above Example 6 and Comparative Example 6 ₁ ,
The measurement results of 6 ₂ are as shown in Table 6 below.

[0101]

[Table 6]

The comparative example 6 ₁ , 6 ₂ is the same as the comparative example 6 ₁ , 6 _{2 in} which the diphenoquinone of the chemical formula (2) is used as the charge transfer material.
It is clearly more sensitive than that of the chemical formula of
It can be seen that the diphenoquinone of (2) improves the sensitivity by the electron transfer action.

As described above, the diphenoquinone compound represented by the general formula (1) as the charge transfer substance used in the present invention has the following characteristics.

In order to develop a highly sensitive positive charging type electrophotographic photoreceptor, an electron transfer substance having high mobility is required. In order to become an electron transfer substance, it must have a high electron accepting property, but the diphenoquinone compound of the present invention is
Very high electron accepting property. The diphenoquinone compound of the present invention has extremely good compatibility with the resin used as the binder of the photosensitive layer, and it is possible to uniformly disperse the charge-transfer layer in an amount satisfying the electrical characteristics at a high concentration. The diphenoquinone compound of the present invention, even when added to a negatively charged electrophotographic photoreceptor, has the effect of improving the sensitivity and lowering the residual potential by the electron transfer action thereof,
It can also be used for high-sensitivity negative charging type electrophotographic photoreceptors.

<Other Examples> Examples of the conductive substrate that can be used in the present invention include aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum and indium. Processed bodies of simple metals or their alloys, or plastic plates and films that are made conductive by processing conductive materials such as the above metals and carbon by vapor deposition and plating, and tin oxide, indium oxide, and iodide Conductive glass, etc. coated with aluminum,

Various conductive materials can be used without being limited by the type and shape of the conductive substrate. In general, a cylindrical aluminum tube alone, a material whose surface is anodized, or a material coated with a conductive resin is often used.

As the charge generating substance that can be used in the electrophotographic photosensitive member of the present invention, the above-mentioned disazo pigment and oxytitanyl phthalocyanine are preferable in that they are compatible with each other in sensitivity, but are not limited thereto, and For example, selenium, selenium tellurium, selenium-arsenic, amorphous silicon, other phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, polyazo pigments, indigo pigments, slene pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, pyrylium salts. Etc. can be used.

These charge generating substances may be used alone or in combination of two or more in order to obtain appropriate photosensitivity wavelength and sensitizing action.

Further, the above general formula (1) used in the present invention is
X of the charge transfer substance represented by is not limited to chlorine and may be any electron withdrawing group. Specifically, when X is a cyano group, a compound represented by the following chemical formula (6),

[0110]

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Is obtained as a charge transfer material, and when X is a nitro group, a compound represented by the following chemical formula (7) is obtained as a charge transfer material.

[0112]

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R _{1 to} R ₃ in the general formula (1) are te
It is not limited to the rt-butyl group, and for example, in the case of a methyl group, a compound represented by the following chemical formula (8),

[0114]

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Is obtained as a charge transfer material. The diphenoquinone compound represented by the above chemical formula (1) may be used alone or in combination of two or more. Further, the diphenoquinone compound represented by the chemical formula (1) is preferably contained in the photosensitive layer in a concentration of 0.1% by weight to 80% by weight.

Further, it is possible to add another charge transfer material to the charge transfer material represented by the general formula (1), and in that case, the sensitivity can be increased and the residual potential can be lowered. The characteristics of the electrophotographic photoreceptor of the present invention can be improved.

As the charge transfer substance which can be added for improving the characteristics, polyvinylcarbazole, a polymer compound,
Halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, polyisothianaphthene, polyaniline, polydiacetylene, polyhepta Conductive polymer compounds such as diene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, and polyphthalocyanine can be used.

As the low molecular weight compounds, polycyclic aromatic compounds such as anthracene, pyrene and phenanthrene, nitrogen-containing heterocyclic compounds such as indole, carbazole and imidazole, fluorenone, fluorene, oxadiazole,
Oxazole, pyrazoline, hydrazone, triphenylmethane, triphenylamine, enamine, stilbene compounds and the like can be used.

Further, a polymer solid electrolyte in which a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile or polymethacrylic acid is doped with a metal ion such as Li ion can also be used.

Further, an organic charge transfer complex formed of an electron donor compound and an electron acceptor compound represented by tetrathiafulvalene-tetracyanoquinodimethane can also be used. Even if only one kind is added, Even if two or more compounds are mixed and added, desired photoconductor characteristics can be obtained.

The binder resin which can be used for forming the photosensitive layer includes polycarbonate resin, styrene resin, acrylic resin, styrene-acrylic resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, chlorinated polyether, Vinyl chloride-vinyl acetate resin, polyester resin, furan resin, nitrile resin,
Alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diarylate resin, polysulfone resin, polyethersulfone resin, polyallylsulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, There are photocurable resins such as polyether resin, phenol resin, EVA resin, ACS resin, ABS resin and epoxy arylate. Even if these are used alone,
A copolymer may be used, and it is also possible to use a mixture of two or more thereof. In addition, it is preferable to use a mixture of resins having different molecular weights because hardness and abrasion resistance can be improved.

The solvent used for the coating solution is methanol,
Ethanol, n-propanol, i-propanol, alcohols such as butanol, pentane, hexane, heptane, octane, cyclohexane, saturated aliphatic hydrocarbons such as cycloheptane, toluene, aromatic hydrocarbons such as xylene, dichloromethane, dichloroethane, Chlorine hydrocarbons such as chloroform and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran and methoxyethanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl formate, propyl formate, methyl acetate, ethyl acetate , Esters such as propyl acetate, butyl acetate and methyl propionate, N, N-dimethylformamide, dimethyl sulfoxide and the like. These may be used alone or as a mixture of two or more solvents.

The coating liquid for producing the photoreceptor of the present invention contains an antioxidant, an ultraviolet absorber, a radical scavenger, a softening agent, a curing agent, as long as the characteristics of the electrophotographic photoreceptor are not impaired.
A crosslinking agent or the like can be added, and the characteristics, durability and mechanical characteristics of the photoconductor can be improved.

Furthermore, by adding a dispersion stabilizer, an anti-settling agent, an anti-color separation agent, a leveling agent, a defoaming agent, a thickener, a matting agent, etc., the finished appearance of the photoreceptor and the life of the coating liquid can be improved. Can be improved, which is preferable.

In the electrophotographic photosensitive member of the present invention, an undercoat layer having an adhesive function, a barrier function, a defect covering function on the surface of the support and the like may be provided between the conductive support and the photosensitive layer. As the undercoat layer, aluminum oxide, polyethylene resin, acrylic resin, epoxy resin, polycarbonate resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, polyamide resin, nylon resin and the like can be used. These undercoat layers may be composed of a single resin, or may be composed of a mixture of two or more resins. Further, an undercoat layer in which a metal oxide or carbon is dispersed in a resin can be used.

On the photosensitive layer, an organic thin film of polyvinyl formal resin, polycarbonate resin, fluororesin, polyurethane resin, silicon resin or the like, or a thin film composed of a siloxane structure formed of a hydrolyzate of a silane coupling agent is formed. A film may be formed to provide a surface protective layer, which is preferable because the durability of the photoreceptor is improved. This surface protective layer may be provided to improve functions other than the enhancement of durability.

[0127]

EFFECT OF THE INVENTION Since the photosensitive layer can be composed of an electron transfer material having good compatibility, a large amount can be uniformly dispersed in the photosensitive layer, and a high-sensitivity electrophotographic photosensitive member having excellent characteristics can be obtained.

Since the photosensitive layer contains an electron transfer substance, it can be used in a positive charging system.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of a single layer dispersion type electrophotographic photosensitive member of the present invention. FIG. 1B is a cross-sectional view of a function-separated electrophotographic photosensitive member which is another example of the present invention.

[Explanation of symbols]

2 ... Electrophotographic photoreceptor 3 ... Conductive substrate 4, 14
...... Photosensitive layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masato Nanasawa 1-8-10 Satokichi, Kofu-shi, Yamanashi

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the following general formula (1): (In the general formula (1), X is a halogen, a cyano group,
Alternatively, any one of nitro groups is shown. R ₁ , R ₂ , R ₃
Are saturated hydrocarbons, which may be the same or different from each other. ) A diphenoquinone compound represented by the formula (1) is contained as a charge transfer substance. 2. The electrophotographic photosensitive member according to claim 1, wherein X in the diphenoquinone compound represented by the general formula (1) is chlorine (Cl). 3. The diphenoquinone compound represented by the general formula (1), wherein each of R ₁ , R ₂ and R ₃ is a tert-butyl group. Or the electrophotographic photosensitive member according to item 1. 4. The charge generating material used in the photosensitive layer contains at least one of a disazo pigment and oxytitanyl phthalocyanine.
To the electrophotographic photosensitive member according to claim 3. 5. The diphenoquinone compound has the following chemical formula (2): (In the chemical formula (2), tBu represents a tert-butyl group.) In the compound represented by the chemical formula (2), the diphenoquinone compound is represented by the following chemical formula (3): The electrophotographic photosensitive member according to claim 3, which is synthesized by bringing HCl gas into contact with a liquid in which the compound represented by the formula (3) is dissolved.