JP2660867B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a low molecular organic photoconductor that provides improved electrophotographic properties.

[Prior Art] Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used for a photosensitive layer for electrophotography, but recently, an organic photoconductive material has been used as an electrophotographic photoreceptor. The research used is actively being conducted.

The basic characteristics required of an electrophotographic photoreceptor are that it is charged to an appropriate potential by corona discharge in a dark place, that the charge retention rate in a dark place is good, and that the charge is quickly discharged by light irradiation. And low residual potential after light irradiation.

Conventional electrophotographic photoreceptors using inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have basic characteristics to some extent, but have difficulty in film formation, poor flexibility, and manufacturing. There are manufacturing problems such as high cost.

Further, inorganic photoconductive materials are generally highly toxic, and from this aspect, conversion of an inorganic substance to an organic substance to a photoreceptor is desired.

Generally, organic compounds have advantages such as light weight, excellent film-forming properties and flexibility, low production cost, and low toxicity compared to inorganic compounds. Electrophotographic photoreceptors have been proposed and put into practical use.

By the way, various organic photoconductive polymers including poly-N-vinylcarbazole have been proposed as typical examples of the organic electrophotographic photoreceptors proposed so far. Compared to inorganic photoconductive materials, they are superior in terms of lightness and film formability, but are inferior in sensitivity, durability, stability due to environmental changes, mechanical strength, etc. there were.

Further, hydrazone compounds disclosed in U.S. Pat.No. 4,150,087, triarylpyrazoline compounds described in U.S. Pat. Low molecular organic photoconductors have been proposed.

Such low-molecular organic photoconductors can be used in the field of organic photoconductive polymers to solve the problem of film-forming properties by appropriately selecting the binder to be used. It is not enough in terms of.

For these reasons, a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has recently been proposed. The electrophotographic photoreceptor having this laminated structure as a photosensitive layer can be improved in terms of sensitivity to visible light, charge retention, surface strength, and the like.

Many organic compounds have been mentioned as charge transport materials. For example, pyrazoline compounds disclosed in JP-A-52-72231, hydrazone compounds disclosed in U.S. Patent No. 842431 and JP-A-55-52063, JP-A-57-195254 and U.S. Patent No. 965970 And the stilbene compounds disclosed in JP-A-54-151955 and JP-A-58-198043.

However, the sensitivity and characteristics of conventional electrophotographic photoreceptors using a low-molecular-weight organic compound as the charge transport material are not always sufficient, and the fluctuations in the light and dark potentials after repeated charging and exposure are performed. But there are still points to be improved.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photosensitive member which has solved the above-mentioned various disadvantages of the conventional electrophotographic photosensitive member, and is easy to manufacture and relatively inexpensive. And to provide a novel organic photoconductor having excellent durability.

[Means for Solving the Problems and Action] The present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has the following general formula (I) or (II):
And an electrophotographic photosensitive member containing at least one compound selected from the compounds represented by (III).

General formula In the formula, Ar ₁ and Ar ₂ represent an aryl group or an aromatic heterocyclic group which may have a substituent, and R represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group or a hydroxyl group. .

Specifically, as the aryl group, a group such as phenyl, naphthyl, and anthranyl; as the aromatic heterocyclic group, a group such as pyridine, quinoline, thienyl, and furyl; as the alkyl group, a group such as methyl, ethyl, and propyl; Examples of the group include groups such as methoxy and ethoxy.

The substituents in the aryl group, aromatic heterocyclic group, alkyl group and alkoxy group include alkyl groups such as methyl, ethyl and propyl, methoxy, ethoxy,
Examples include an alkoxy group such as propoxy, and a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom.

Hereinafter, typical examples of the compounds represented by formulas (I), (II) and (III) will be listed.

Compound of General Formula (I) Compound Example (1-1) Compound example (1-2) Compound example (1-3) Compound example (1-4) Compound example (1-5) Compound example (1-6) Compound example (1-7) Compound example (1-8) Compound example (1-9) Compound example (1-10) Compound example (1-11) Compound example (1-12) Compound example (1-13) Compound example (1-14) Compound example (1-15) Compound example (1-16) Compound example (1-17) Compound example (1-18) Compound of general formula (II) Compound example (2-1) Compound example (2-2) Compound example (2-3) Compound example (2-4) Compound example (2-5) Compound example (2-6) Compound example (2-7) Compound example (2-8) Compound example (2-9) Compound example (2-10) Compound example (2-11) Compound example (2-12) Compound example (2-13) Compound example (2-14) Compound example (2-15) Compound example (2-16) Compound example (2-17) Compound example (2-18) Compound of general formula (III) Compound example (3-1) Compound example (3-2) Compound example (3-3) Compound example (3-4) Compound example (3-5) Compound example (3-6) Compound example (3-7) Compound example (3-8) Compound example (3-9) Compound example (3-10) Compound example (3-11) Compound example (3-12) Compound example (3-13) Compound example (3-14) Compound example (3-15) Compound example (3-16) Compound example (3-17) Compound example (3-18) [Synthesis Example] Synthesis of Compound Example (1-3) 14.3 g (70 mol) of p-iodotoluene, 5.5 g (28 mmol) of 2-amino-9,10-dihydrophenanthrene, 9.7 g (70 g) of anhydrous potassium carbonate Mmol) and copper powder
13 g was added to 50 ml of nitrobenzene, and the mixture was heated under reflux with stirring under a nitrogen atmosphere for 12 hours. After allowing to cool, suction filtration was performed, and nitrobenzene was removed from the filtrate under reduced pressure. Ethanol was added to the residue to precipitate crystals, and the crude crystals were separated and purified by a silica gel column to obtain the target compound.

Yield: 5.9 g, 56%. Elemental analysis was as follows, as C ₂₈ H ₂₅ N.

Calculated value (%) Actual value (%) C 89.56 89.54 H 6.71 6.75 N 3.73 3.71 Compound example (Synthesis of 2-3 2- (p-ditolyl) amino-9,10-dihydrophenanthrene 10 g (26.6 mmol) 0.9 g of 10% palladium carbon was gradually heated with stirring in 30 ml of xylene.
At ℃ began foaming. The temperature was kept at 130 to 140 ° C. 1 and the additional stirring was continued for 3 hours. After cooling, 200 ml of hexane was added and the mixture was filtered. The solvent was removed from the filtrate under reduced pressure, and hexane was added to precipitate crystals. The target compound was obtained by recrystallization from a mixed solution of toluene and hexane. The yield was 6.5 g, and the yield was 65%. Elemental analysis was as follows, as C ₂₈ H ₂₃ N.

Calculated value (%) Actual value (%) C 90.04 90.02 H 6.21 6.24 N 3.75 3.74 Synthesis of compound example (3-3) 9-aminophenanthrene 5.4 g (28 mmol), p-
14.3 g (70 mmol) of iodotoluene, 9.7 g (70 mmol) of anhydrous potassium carbonate and 13 g of copper powder were added to nitrobenzene 5
The mixture was added to 0 ml and heated under reflux with stirring for 10 hours.

After allowing to cool, suction filtration was performed, and nitrobenzene was removed from the filtrate under reduced pressure. Ethanol was added to the residue to precipitate crystals, and the crude crystals were separated and purified by a silica gel column to obtain the target compound.

The yield was 6.5 g, and the yield was 65%. Elemental analysis was as follows, as C ₂₈ H ₂₃ N.

 Calculated value (%) Actual value (%) C 90.04 90.03 H 6.21 6.24 N 3.75 3.73 The drawing shows the infrared absorption spectrum (KBr tablet method).

In addition, compounds other than the synthesis examples are generally synthesized in the same manner.

In the electrophotographic photoreceptor of the present invention, examples of the constitution of the photosensitive layer include the following.

Layer containing charge generating substance / layer containing charge transporting substance Layer containing charge transporting substance / layer containing charge generating substance Layer containing charge generating substance and charge transporting substance Layer containing charge generating substance / charge Layer Containing Generating Substance and Charge Transport Material In the present invention, the compounds represented by the general formulas (I) to (III) have a high hole-transporting ability, so that they are used as the charge transport material in the photosensitive layer of the above embodiment. Can be used.

In the case of the photosensitive layer, negative charging is preferable, and in the case of positive photosensitive charging, both positive charging and negative charging can be used.

Further, in the electrophotographic photoreceptor of the present invention, an appropriate intermediate layer may be provided between the conductive support and the photosensitive layer, or a protective layer or an insulating layer may be provided on the surface of the photosensitive layer in order to improve adhesion and control charge injection. It may be provided.

The configuration of the electrophotographic photoreceptor of the present invention is not limited to the above basic configuration.

 In addition, the form of the above configuration is preferable.

Examples of the conductive support include the following forms.

Aluminum, aluminum alloy, stainless steel, copper or other metal in plate or drum shape Aluminum, palladium, rhodium, gold, on a non-conductive support such as glass, resin, paper or conductive support
Thin films formed by vapor deposition or lamination of metals such as platinum Conductive compounds such as conductive polymers, tin oxide, and indium oxide on non-conductive supports such as glass, resin, and paper and conductive supports Formed by depositing or applying a layer of

Examples of the charge generating substance include the following substances.

These charge generating substances may be used alone or in combination of two or more.

Azo pigments such as monoazo, disazo and trisazo Phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine Indigo pigments such as indigo and thioindigo Perylene pigments such as perylene anhydride and perylene imide Polycyclic such as anthraquinone and pyrenequinone Quinone pigments squarylium pigments pyrylium salts, thiopyrylium salts triphenylmethane pigments inorganic materials such as selenium, amorphous silicon, etc. A layer containing a charge generation material, that is, a charge generation layer is formed by appropriately combining the above charge generation materials. It can be formed by dispersing in an adhesive and applying this on a conductive support. Further, it can also be formed by forming a thin film on a conductive support by a dry method such as evaporation, sputtering, or CVD.

The binder can be selected from a wide range of binder resins, such as polycarbonate, polyester, polyarylate, butyral resin, polystyrene, polyvinyl acetal, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenolic resin, and silicone. Examples include, but are not limited to, resins, polysulfones, styrene-butadiene copolymers, alkyd resins, epoxy resins, urea resins, vinyl chloride-vinyl acetate polymers, and the like.

 These may be used alone or in combination of two or more.

The resin contained in the charge generation layer is at most 80% by weight, preferably at most 40% by weight.

The thickness of the charge generation layer is 5 μm or less, preferably 0.01 to 1 μm.
It is a thin film layer in the range of μm.

Various sensitizers may be added to the charge generation layer.

The layer containing the charge transporting substance, that is, the charge transporting layer, can be formed by combining the compounds represented by the above general formulas (I) to (III) with an appropriate binder resin.

Examples of the binder resin used in the charge transport layer include the resins used in the charge generation layer, and further include photoconductive polymers such as polyvinyl carbazole and polyvinyl anthracene.

The compounding ratio of the binder and the compounds represented by the general formulas (I) to (III) is 10 to 5 per 100 parts by weight of the binder.
Preferably it is 00 parts by weight.

The thickness of the charge transport layer is 5 to 40 μm, preferably 10 to 30 μm.
m.

Furthermore, an antioxidant, an ultraviolet absorber,
Excess material or a known charge transport material can be added as needed.

When the charge transport layer is formed, a suitable organic solvent can be used by a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a coating method such as a blade coating method. .

The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, and electrophotographic plate making systems.

[Example] Example 1 Structural formula 4 g of disazo pigment in butyral resin (butyralization degree 63
(Mol%) was dispersed in a sand mill for 24 hours together with a solution of 2 g in 100 ml of cyclohexanone to prepare a coating solution.

The coating liquid was applied on an aluminum sheet using a Meyer bar so as to have a dry film thickness of 0.2 μm, and dried to form a charge generation layer.

Next, 9 g of the compound (1-6) as a charge transport material and 10 g of polycarbonate (average molecular weight: 20,000) are dissolved in 70 g of chlorobenzene, and this solution is applied on the charge generation layer with a Meyer bar, and then dried. A charge transport layer having a thickness of 20 μm was formed, and an electrophotographic photosensitive member was manufactured.

This electrophotographic photoreceptor was statically charged at -5 KV using an electrostatic copying paper tester Model-SP-428 manufactured by Kawaguchi Electric Co., Ltd.
After charging for 1 second in a dark place, exposure was performed at an illuminance of 20 lux, and charging characteristics were examined.

As the charging characteristics, the exposure required to decay the surface potential (V ₀₎ and one second dark decay was when potential (V ₁₎ to 1/2 (E1 /
2) was measured.

Furthermore, in order to measure the fluctuations in the light-area potential and the dark-area potential during repeated use, the above electrophotographic photosensitive member was attached to a photosensitive drum cylinder of a PPC copier (NP-3525, manufactured by Canon Inc.). 5,000 copies are made on the same machine, and the bright part potential (V _L ) and dark part potential (V
_D ) Variation was measured.

Incidentally, the initial V _D and V _L were set to respectively -700 V, and -200 V.

 The results are shown.

V ₀ : −698 V, V ₁ : −690 V, E1 / 2: 1.5 lux / sec Initial potential V _D : −700 V, V _L : −200 V Potential after endurance of 5,000 sheets V _D : −690 V, V _L : −290 V Examples 2 to 10 Examples of compounds which are charge transport materials used in Example 1 (1-
In place of the compound of 6), compound examples (1-1) and (1-
2), (1-3), (1-7), (1-9), (1-1)
8) Using the compounds of (2-3), (2-15) and (3-3) as the charge generating substance, Each electrophotographic photoreceptor was manufactured in the same manner as in Example 1 except that the above pigment was used.

The electrophotographic characteristics of each electrophotographic photoreceptor were measured in the same manner as in Example 1. The results are described below.

Comparative Examples 1 to 3 For comparison, an electrophotographic photosensitive member was manufactured in the same manner as in Example 2 except that a compound having the following structural formula was used as a charge transporting substance, and electrophotographic characteristics were measured in the same manner. The results are shown.

Comparative compound example (1) (JP-A-57-195245) (2) (Japanese Patent Publication No. 58-32372) (3) (JP-A-58-198043) Example 11 A solution prepared by dissolving 5 g of methoxymethylated nylon (average molecular weight: 30,000) and 10 g of alcohol-soluble copolymerized nylon (average molecular weight: 25,000) in 95 g of methanol on an aluminum substrate was applied by a Meyer bar and dried. An undercoat layer having a thickness of 1 μm later was provided.

Next, the structural formula 15 g of disazo pigment, butyral resin (butyralization degree 6
3 g%) 10 g and dioxane 320 g are mixed with a ball mill dispersing machine 48
Time dispersion was performed, and this dispersion was applied on the previously formed undercoat layer by a blade coating method to form a charge generation layer having a thickness of 0.2 μm after drying.

Next, 11 g of the compound of compound example (3-3) and 10 g of polymethyl methacrylate (average molecular weight: 50,000) were dissolved in 70 g of chlorobenzene, and the prepared coating solution was applied on the charge generation layer by a blade coating method. The film thickness after drying
An 18 μm charge transport layer was formed.

The thus produced electrophotographic photosensitive member was subjected to a corona discharge of -5 KV. The surface potential at this time was measured (initial potential
V ₀ ). Further, the surface potential of this photoconductor after leaving it in a dark place for 1 second was measured.

Sensitivity, exposure required to attenuate the potential V ₁ of the after dark decay to 1/2 was evaluated by (E1 / 2 microjoules / cm ²⁾ measured.

At this time, a ternary semiconductor laser of gallium / aluminum / arsenic (output: 5 mw, oscillation wavelength: 780 nm) was used as a light source.

 The results are shown.

V ₀ : −670 V V ₁ : −665 V E1 / 2: 0.33 μJ / cm ² Next, a laser beam printer (LBP-CX, Canon Inc.), which is an electrophotographic printer of the reversal development type equipped with a semiconductor laser as described above. The above photoreceptor was set in (1), and an actual image forming test was performed. However, the conditions were changed as follows.

Surface potential after primary charging: -700 V, surface potential after image exposure: -150 V (exposure amount: 0.6 μJ / cm ² ), transfer potential: +700 V,
Developer polarity: negative polarity, process speed: 50 mm / sec, development conditions (development bias): -450 V, image exposure scan method: image scan, primary charging pre-exposure: 20 lux sec red exposure, image formation with laser beam Was performed by line scanning according to a character signal and an image signal.

 Good prints were obtained for both characters and images.

Furthermore, when 3,000 continuous images were output, stable and good prints were obtained from the initial stage to 3,000 pages.

Example 12 10 g of titanine phthalocyanine was 485 g of cyclohexanone
Was added to a solution prepared by dissolving 4 g of a phenoxy resin, and dispersed in a ball mill for 2 hours. This dispersion was applied on an aluminum sheet with a Meyer bar and dried at 80 ° C. for 2 hours to form a 0.2 μm charge generation layer.

Next, a solution prepared by dissolving 9.5 g of the compound of the compound example (3-1) and 10 g of bisphenol Z-type polycarbonate (weight average molecular weight: 50,000) in 70 g of chlorobenzene was applied on the above-mentioned charge generating layer with a Meyer bar, and then heated to 110 ° C. Dry for 1 hour with 17μ
m of the charge transport layer was formed.

The electrophotographic characteristics of the produced electrophotographic photosensitive member were measured by the same method as in Example 11.

 The results are shown.

V ₀ : −650 V V ₁ : −645 V E1 / 2: 0.30 μJ / cm ² Example 13 4- (4′-dimethylaminophenyl) -2,6-diphenylthiapyrylium perchlorate 3 g and a compound example (3
5 g of the compound of -7) in 100 g of a toluene-dichloromethane (50:50) solution of polyester (weight average molecular weight 49,000)
And dispersed in a ball mill for 6 hours.

This dispersion was applied to an aluminum sheet with a Meyer bar and dried at 100 ° C. for 2 hours to form a photosensitive layer having a thickness of 18 μm.

The electrophotographic photoreceptor thus manufactured was measured for electrophotographic characteristics in the same manner as in Example 1.

V ₀ : −671 V, V ₁ : −666 V, E1 / 2: 2.2 lux / sec Initial potential V _D : −700 V, V _L : −200 V Potential after 5,000 sheets endurance V _D : −680 V, V _L : −213 V Examples 14 to 18 Examples of the compound as the charge transporting substance used in Example 11 (3-
Instead of the compound of 3), compound examples (3-1) and (3-
2), (3-8), (3-16) and (3-18), except that the electrophotographic photoreceptors were produced in the same manner as in Example 11, except that the compounds of (3-18) were used.

The electrophotographic characteristics of each photoconductor were measured by the same method as in Example 11. The results are described below.

Comparative Examples 4 and 5 For comparison, an electrophotographic photosensitive member was produced in the same manner as in Example 14 except that a compound having the following structural formula was used as a charge transporting substance, and electrophotographic characteristics were measured in the same manner. The results are shown.

Comparative compound example (4) (JP-A-57-195254) (5) (JP-B-63-180954) Example 19 Aqueous ammonia solution of casein (casein on an aluminum plate)
11.2 g, 1 g of 28% aqueous ammonia, and 222 ml of water) were applied with a Meyer bar to form an undercoat layer having a dry film thickness of 1 μm.

The same charge transport layer and charge generation layer as in Example 4 were sequentially laminated thereon, and an electrophotographic photosensitive member was manufactured in the same manner except that the layer configuration was different.

The electrophotographic characteristics of the electrophotographic photosensitive member were measured in the same manner as in Example 1. The results are shown. However, the charging polarity was positive.

V ₀ : +698 V, V ₁ : +688 V, E1 / 2: 2.5 lux / sec Example 20 A 5% methanol solution of soluble nylon (6-66-610-12 quaternary nylon copolymer) was applied on an aluminum plate. An undercoat layer having a dry film thickness of 0.5 μm was formed. Next, the structural formula 5 g of the pigment in 95 ml of tetrahydrofuran with a sand mill
Time dispersed.

Next, 5 g of the compound of compound example (3-4) and 10 g of bisphenol Z-type polycarbonate (weight average molecular weight: 50,000)
Was dissolved in 30 ml of chlorobenzene, added to the above dispersion, and further dispersed for 2 hours by a sand mill.

This dispersion was applied on a subbing layer with a Meyer bar so that the film thickness after drying was 17 μm, and dried to produce an electrophotographic photoreceptor.

The electrophotographic characteristics of this electrophotographic photosensitive member were measured in the same manner as in Example 1.

 The results are shown.

V ₀ : +650 V, V ₁ : +645 V, E1 / 2: 1.5 l1 ux · sec [Effect of the Invention] The electrophotographic photoreceptor of the present invention has the general formulas (I) to (III)
By using the compound as a charge transport material, a remarkable effect is obtained in that the sensitivity is high, the fluctuation in the light-part potential and the dark-part potential is small in continuous image formation by repeated charging and exposure, and the durability is excellent.

[Brief description of the drawings]

The figure shows the infrared absorption spectrum (KB) of Compound Example (3-3).
r tablet method).

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has the following general formula (I) or (II):
And an electrophotographic photoreceptor containing at least one compound selected from the compounds represented by (III). General formula In the formula, Ar ₁ and Ar ₂ represent an aryl group or an aromatic heterocyclic group which may have a substituent, and R represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group or a hydroxyl group. .