JPH0797223B2 - Organic photoconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an organic photoconductor, and more particularly to an organic photoconductor suitable as a photoconductor for electrophotography.

<Problems to be Solved by Conventional Techniques and Inventions> In recent years, as an electrophotographic photoreceptor, an organic photoreceptor having good processability and advantageous in terms of manufacturing cost and having a large degree of freedom in functional design has been used. ing. Among them, the function-separated type organic photoconductor is known because each function is separated by the charge-generating material that generates charges by light irradiation and the charge-transporting material that transports the generated charges to improve sensitivity. Has been. For example, a single-layer type photoconductor (JP-A-56-143438) in which a polycyclic aromatic hydrocarbon is contained in a polyvinylcarbazole-based photoconductor as a charge transport material, or on a conductive substrate, A multi-layer type photoreceptor in which a charge generation layer containing a perylene pigment as a charge generation material and a charge transport layer containing a specific hydrazone compound as a charge transport material are laminated (JP-A-55-156954). (See Japanese Patent Publication).

The above single-layer type photoconductor can be obtained by simply dispersing a polycyclic aromatic hydrocarbon in a polyvinylcarbazole-based photoconductor, applying it to a conductive substrate, and drying it to obtain a photoconductor. Good sex. Further, in the above-mentioned single-layer type photoconductor, not only can it be positively charged, but generally, as the toner for developing the electrostatic latent image of the photoconductor, a negatively charged toner can be easily obtained. It has the advantage that it is wide and that various toner materials can be used.
However, the sensitivity of the single-layer type photoconductor in which polycyclic aromatic hydrocarbons are dispersed in the polyvinylcarbazole-based photoconductor is not sufficient, and the material forming the photoconductor layer is strictly selected. Therefore, the selection range of the material of the photosensitive layer is narrow. Further, the single-layer type photoconductor not only has a low surface potential at the time of corona charging, and also has a large residual potential,
Since the surface potential is lowered by repeated use, there is a problem that the repeating characteristics are not sufficient and the organic photoreceptor does not exhibit sufficient characteristics.

On the other hand, since the multi-layer type photoconductor separates the respective functions by the charge generation layer and the charge transport layer, unlike the single layer type photoconductor, the sensitivity is high and the selection range of the photosensitive material is high. It has the advantage of being wide. However, since the charge-transporting material is generally a hole-transporting substance, it is possible to negatively charge the photoconductor, but it is difficult to positively charge the photoconductor.
Contrary to the single layer type photoreceptor, the selection range of the toner material is narrowed. Further, since the layer thickness of the charge generation layer is as thin as 1 to 2 μm, not only the charge generation layer must be accurately formed, but also the charge transport layer must be formed on the charge generation layer. The number of manufacturing steps is increased, the workability is poor, the yield is low, and the cost is high. Furthermore, since ozone is generated when negatively charged by corona discharge,
In a copying machine or the like, it is necessary to provide an exhaust passage for exhausting ozone, which causes a problem that the device becomes large.

<Objects of the Invention> The present invention has been made in view of the above problems, and provides an inexpensive single-layer organic photoreceptor having excellent positive charging property, high sensitivity and high surface potential, and small residual potential. The purpose is to

<Means and Actions for Solving Problems> In order to achieve the above object, the organophotoreceptor of the present invention has a photosensitive layer having a single-layer type photosensitive layer composed of a charge generating material, a charge transporting material and a binder resin. In the body, the charge generation material is a perylene-based compound represented by the following general formula (1), and the charge-transporting material is a hydrazone-based compound represented by the following general formula (2). is there.

(In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a lower alkyl group or a lower alkoxy group.) (In the formula, R ⁵ represents a hydrogen atom or a lower alkyl group.) The present invention is described in detail below.

The organic photoreceptor of the present invention has a single-layer type photosensitive layer,
It is composed of a perylene compound represented by the general formula (1) as the charge generation material, a hydrazone compound represented by the general formula (2) as the charge transport material, and a binder resin. .

Examples of the lower alkyl group in the general formula (1) and the general formula (2) include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl,
An alkyl group having 1 to 6 carbon atoms such as a hexyl group is exemplified.

Examples of the lower alkoxy group in the general formula (1) include alkoxy groups having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy groups. To be done.

Examples of the perylene-based compound represented by the general formula (1) include N, N'-di (3,5-dimethylphenyl) perylene-3,
4,9,10-Tetracarboxydiimide, N, N'-di (3-
Methyl-5-ethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-diethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N , N'-di (3,5-dipropylphenyl) perylene-
3,4,9,10-tetracarboxydiimide, N, N'-di (3,5
-Diisopropylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-dibutylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N ' -Di (3,5-di-tert-butylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-
Di (3,5-dipentylphenyl) perylene-3,4,9,10-
Tetracarboxydiimide, N, N'-di (3,5-dihexylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3-methyl-5-methoxyphenyl) perylene- 3,4,9,10-tetracarboxydiimide,
N, N'-di (3-methyl-5-ethoxyphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-
Di (3-ethyl-5-methoxyphenyl) perylene-3,
4,9,10-Tetracarboxydiimide, N, N'-di (3-
Propyl-5-methoxyphenyl) perylene-3,4,9,10
-Tetracarboxydiimide, N, N'-di (3,5-dimethoxyphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-diethoxyphenyl) perylene- 3,4,9,10-tetracarboxydiimide, N, N'-
Di (3,5-dipropoxyphenyl) perylene-3,4,9,10
-Tetracarboxydiimide, N, N'-di (3,5-diisopropoxyphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-diptoxyphenyl) Perylene-3,4,9,10-tetracarboxydiimide,
N, N'-di (3,5-dipentyloxyphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-dihexyloxyphenyl) perylene-3,4, 9,1
Examples include 0-tetracarboxydiimide and the like. Of the above perylene compounds, those having an alkyl group or an alkoxy group having 1 to 3 carbon atoms, particularly N, N'-di (3,5
-Dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide is preferred. The perylene compounds may be used alone or in combination of two or more.

The hydrazone-based compound represented by the general formula (2) includes 3-carbazolyl aldehyde, N, N-diphenylhydrazone, N-methyl-3-carbazolyl aldehyde, N, N-diphenylhydrazone, N-ethyl-3-
Carbazolylaldehyde N, N-diphenylhydrazone, N-propyl-3-carbazolylaldehyde, N, N
-Diphenylhydrazone, N-isopropyl-3-carbazolylaldehyde N, N-diphenylhydrazone, N
-Butyl-3-carbazolylaldehyde N, N-diphenylhydrazone, N-isobutyl-3-carbazolylaldehyde N, N-diphenylhydrazone, N-tert-butyl-3-carbazolylaldehyde N, N-diphenyl Hydrazone, N-pentyl-3-carbazolylaldehyde N, N-diphenylhydrazone, N-hexyl-3-
An example is carbazolyl aldehyde N, N-diphenylhydrazone. Among the hydrazone compounds, those having an alkyl group having 1 to 3 carbon atoms, particularly N-methyl-
3-carbazolyl aldehyde N, N-diphenylhydrazone is preferred. The hydrazone compounds are used alone or in combination of two or more.

Further, as the above-mentioned binder resin, various ones, for example, a styrene polymer, an acrylic polymer, a styrene-acrylic copolymer, polyethylene, an ethylene-vinyl acetate copolymer, a chlorinated polyethylene, a polypropylene, an ionomer. Olefin polymer such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl Butyral resin, polyether resin, phenol resin, photo-curable resin such as epoxy acrylate, etc.
Although various polymers can be used, the sensitivity of the photoconductor is increased, the compatibility with the above-mentioned hydrazone compounds, the abrasion resistance of the photoconductor, and the excellent repeatability, and the selection range of the solvent that dissolves the binder resin is wide. Poly (4,4'-cyclohexylidenediphenyl) carbonate is preferred. Above poly (4,4 ′
When -cyclohexylidenediphenyl) carbonate is used, dichloromethane,
Unlike bisphenol A type polycarbonates which can only use a chlorine-based solvent such as monochlorobenzene, a ketone-based solvent such as tetrahydrofuran or methyl ethyl ketone can also be used, which is preferable in terms of safety and hygiene and easy to handle. As the poly (4,4′-cyclohexylidenediphenyl) carbonate,
Various substances, for example, those having a degree of polymerization of about 50 to 5000 can be used. The binder resins may be used alone or in combination of two or more.

The use ratio of the perylene-based compound, the hydrazone-based compound, and the binder resin can be appropriately selected according to the desired characteristics of the organic photoconductor, etc., but with respect to 100 parts by weight of the binder resin, the perylene-based compound is used. The compound is used in an amount of 2 to 20 parts by weight, preferably 5 to 10 parts by weight, and a hydrazone compound 40 to 110 parts by weight, preferably 60 to 90 parts by weight. When the amount of the perylene-based compound and hydrazone-based compound is less than the above-mentioned amount, not only the sensitivity of the photoconductor is insufficient but also the residual potential becomes large. On the other hand, if it exceeds the above range, the abrasion resistance of the photoconductor becomes insufficient.

Usually, when the above-mentioned perylene-based compound is used in a large amount, the positive charging property becomes insufficient, and when it is a small amount, the sensitivity and the like are lowered, but in the organophotoreceptor of the present invention, the specific perylene-based compound and hydrazone-based compound are used. Therefore, even if the amount of the perylene-based compound is small, it is possible to obtain an organic photoreceptor having a high sensitivity and a high surface potential and a small residual potential and an excellent positive charging property.

Further, the perylene-based compound may have spectral sensitivity on the short wavelength side. Therefore, in applications where color reproducibility in the blue region is required, it is preferable to use various spectral sensitizers, particularly phthalocyanine compounds.

Although various compounds can be used as the phthalocyanine compound, metal-free phthalocyanine is preferable.
The metal-free phthalocyanine may have an appropriate particle size, but an average particle size of 0.1 μm or less is preferable. The average particle size of metal-free phthalocyanine is 0.1 μm
If it exceeds the range, the sensitivity of the photoconductor is lowered. The above average particle diameter is measured by the light scattering method (device name: dynamic light scattering photometer).
It was obtained by.

The metal-free phthalocyanine can be used in an appropriate amount, but is 0.2 to 1 with respect to 100 parts by weight of the binder resin.
It is preferable to add parts by weight. If the added amount is less than 0.2 parts by weight, blue reproducibility is not sufficient, and if it exceeds 1 part by weight, metal-free phthalocyanine has spectral sensitivity in the red region, and red reproducibility becomes insufficient.

Incidentally, among the above metal-free phthalocyanines, β-type metal-free phthalocyanines, particularly 0.005 to 0.0
Those having 5 μm are preferred. If the average particle size of the β-type metal-free phthalocyanine is less than 0.005 μm, the dispersibility is insufficient, and if it exceeds 0.05 μm, the sensitivity of the photoreceptor is lowered.

Further, in order to enhance the stability of the photoreceptor containing the metal-free phthalocyanine, it is preferable to use a phthalocyanine-based pigment such as aluminum phthalocyanine or titanyl phthalocyanine, particularly copper phthalocyanine together with the metal-free phthalocyanine. Further, copper phthalocyanine can be used in an appropriate amount, but is 1 to 10% by weight, particularly 3 to 10% by weight with respect to the metal-free phthalocyanine.
It is preferred to use wt%. If the amount of copper phthalocyanine is less than 1% by weight, it is not sufficient to stabilize the metal-free phthalocyanine, and if it exceeds 10% by weight, the surface potential decreases. As the amount of copper phthalocyanine increases, the stabilizing effect of metal-free phthalocyanine increases and the residual potential of the photoconductor also decreases.

Further, the copper phthalocyanine is even more preferably used in combination with the β-type metal-free phthalocyanine, in which case the copper phthalocyanine has an average particle size of 0.001
It is preferable to use one having a thickness of less than μm. In particular, in order to obtain a stable organic photoconductor having a small residual potential by reducing the amount of copper phthalocyanine, it is preferable to coprecipitate the copper phthalocyanine with metal-free phthalocyanine. The above coprecipitation can be performed by a conventional method, for example, by dropping a sulfuric acid solution of copper phthalocyanine and metal-free phthalocyanine into water or the like at the time of producing copper phthalocyanine. The phthalocyanine obtained by the co-precipitation described above has copper phthalocyanine as fine particles, and not only the deterioration of the electrical characteristics due to the thermal history of the photoconductor is almost eliminated, but also the residual potential is small and a photoconductor having excellent color reproducibility is obtained. To be In the phthalocyanine prepared by the coprecipitation method, a small amount of copper phthalocyanine has an average particle size of 0.001 to enhance blue color reproducibility.
It is preferably μm or less.

The organic photoreceptor having the above composition may use other charge generating material, charge transporting material, etc. within a range that does not impair the photosensitivity and the like. Examples of the charge generation material include selenium, selenium-tellurium, amorphous silicon,
Pyrylium salts, azo pigments, disazo pigments, anthanthrone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments, slene pigments, toluidine pigments, pyrazoline pigments, other perylene pigments,
Examples include quinacridone pigments. Further, as the charge transport material, for example, tetracyanoethylene, 2,4,
Fluorenone compounds such as 7-trinitro-9-fluorenone, nitrated compounds such as 2,4,8-trinitrothioxanthone and dinitroanthracene, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,5-di ( 4-
Oxadiazole compounds such as dimethylaminophenyl) -1,3,4-oxadiazole, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, 1-
Pyrazoline compounds such as phenyl-3- (p-dimethylaminophenyl) pyrazoline, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds Examples thereof include nitrogen-containing cyclic compounds, condensed polycyclic compounds, and the like. Further, conventionally known sensitizers such as terphenyl, halonaphthoquinones and acenaphthylene may be used.

The photosensitive layer of the organic photoreceptor containing the above-mentioned perylene-based compound, hydrazone-based compound, binder resin and the like may have an appropriate thickness, but is 3 to 50 μm, particularly 5 to 20 μm.
Is preferable, and it is formed by preparing a dispersion liquid of the perylene-based compound or the like, applying the dispersion liquid to a conductive substrate, and removing the solvent.

The conductive substrate may be in the form of a sheet or a drum, and it is preferable that the substrate itself has conductivity, or the surface of the substrate has conductivity and has sufficient mechanical strength during use. . As the conductive substrate, various materials having conductivity can be used, for example, aluminum, copper,
Tin, platinum, gold, silver, vanadium, molybdenum, chromium,
Examples include cadmium, titanium, nickel, palladium, indium, stainless steel, brass metal simple substance, plastic material in which the above metal is vapor-deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide and the like. . Among the conductive substrates, aluminum is preferable, and in particular, aluminum crystal grains are not present on the surface, which prevents black spots, pinholes, and the like from being generated in a captured image, and the perylene-based compound and hydrazone-based compound. In order to improve the adhesion between the photosensitive layer containing a compound and the like and the substrate, alumite-treated aluminum, in particular, the thickness of the alumite-treated layer was 5 to 12 μm, and the surface roughness was 1.5 s or less. Aluminum is preferred.

Further, when preparing the above-mentioned dispersion liquid, various organic solvents can be used depending on the kind of the binder resin and the like used. Examples of the solvent include 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, and the like. Diethyl ether,
Examples of various solvents include ethers such as tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformamide, dimethyl sulfoxide, etc. One kind or a mixture of two or more kinds is used. When preparing the above-mentioned dispersion liquid, a surfactant, a leveling agent or the like may be used together in order to improve dispersibility, coatability and the like.

The dispersion can be prepared using a conventional method, for example, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic disperser, etc., and the obtained dispersion is applied to the conductive substrate. Then, the organic photoreceptor of the present invention can be obtained by heating and removing the solvent.

The photosensitive layer of the organic photoreceptor of the present invention contains a specific perylene-based compound and a hydrazone-based compound, and thus is excellent in positive charging property and has sensitivity and surface while having a single-layer structure. High potential and low residual potential. Further, since it is a single-layer type photoreceptor, an inexpensive organic photoreceptor can be easily manufactured with a high yield. Therefore, the organic photoreceptor of the present invention is useful as a photoreceptor used in various applications such as a copying machine and a laser printer.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 N, N'-di (3,5-dimethylphenyl) perylene-3,4,9,
8 parts by weight of 10-tetracarboxydiimide, N-methyl-
3-Carbazolyl aldehyde 75 parts by weight of N, N-diphenylhydrazone, 100 parts by weight of polyester (Vylon RV200 manufactured by Toyobo Co., Ltd.) and a predetermined amount of tetrahydrofuran were used to disperse the dispersion liquid in an ultrasonic disperser. It was prepared and applied onto an aluminum plate that had been anodized to prepare an organic photoreceptor having a photosensitive layer having a thickness of about 20 μm.

Example 2 N-methyl-3-carbazolyl aldehyde of Example 1
An organic photoreceptor was prepared in the same manner as in Example 1 except that N-isopropyl-3-carbazolylaldehyde N, N-diphenylhydrazone was used instead of N, N-diphenylhydrazone.

Example 3 Instead of N, N'-di (3,5-dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide of Example 1, N,
N'-di (3,5-dimethoxyphenyl) perylene-3,4,9,
Example 10 above using 10-tetracarboxydiimide
An organic photoreceptor was prepared in the same manner as in.

Example 4 Instead of the perylene compound and the hydrazone compound of Example 1, N, N'-di (3,5-dimethoxyphenyl) perylene-3,4,9,10-tetracarboxydiimide and N-
Using ethyl-3-carbazolylaldehyde N, N-diphenylhydrazone, an organic photoreceptor was prepared in the same manner as in Example 1 above.

Comparative Example 1 N-methyl-3-carbazolyl aldehyde of Example 1
An organic photoconductor was prepared in the same manner as in Example 1 except that N, N-diethylaminobenzaldehyde N, N-diphenylhydrazone was used instead of N, N-diphenylhydrazone.

Comparative Example 2 N-methyl-3-carbazolyl aldehyde of Example 1
An organic photoreceptor was prepared in the same manner as in Example 1 except that N, N-diethylaminobenzaldehyde N, N-diphenylhydrazone was used instead of N, N-diphenylhydrazone.

Comparative Example 3 Instead of the perylene compound and the hydrazone compound of Example 1, N, N'-dimethylperylene 3,4,9,10-tetracarboxydiimide and N-ethyl-6-methoxy-
Using 3-carbazolylaldehyde N-methyl-N-phenylhydrazone, an organic photoreceptor was prepared in the same manner as in Example 1 above.

Then, in order to investigate the charging characteristic and the photosensitive characteristic of the above-mentioned electrophotographic photosensitive member, an electrostatic copying paper test apparatus (Kawaguchi Electric Co., SP
-428 type), corona discharge was performed under the condition of +6.0 KV to positively charge the organic photoconductors of the respective Examples and Comparative Examples.

The surface potential Vs.p. (V) of each photoconductor was measured, and the illuminance on the photoconductor surface was measured using a tungsten lamp.
The exposure time was adjusted to 10 lux and exposed with a tungsten lamp, the time until the surface potential Vs.p. was reduced to 1/2 was calculated, and the half-exposure amount E 1/2 (μJ / cm ² ) was calculated. . After exposure, the surface potential after 0.15 seconds has passed is the residual potential Vr.p.
(V). In addition, it was also investigated whether or not the surface potential was reduced by repeated use 1000 times. It is to be noted that, when the photoreceptor is repeatedly used, the surface potential of the photoreceptor is hardly lowered, and is marked.

The results of charging characteristics, photosensitive characteristics and repetitive characteristics of the organic photoreceptors obtained in the above Examples and Comparative Examples are shown in the table.

As is clear from the table, it was found that each of the organic photoreceptors of the present invention had a small half-exposure amount, good sensitivity, and a small residual potential. It was also found that the examples all had excellent repetitive characteristics without accumulating residual potential even after repeated use and without increasing residual potential. On the other hand, the photoreceptors of Comparative Examples were not sufficiently sensitive and had a high residual potential. Particularly, in Comparative Example 1, the surface potential was greatly reduced by repeated use, and the repeating characteristics were not sufficient. Further, in Comparative Example 3, the surface potential was low.

<Effects of the Invention> As described above, according to the organic photoreceptor of the present invention, since the photosensitive layer is composed of the specific perylene-based compound, the hydrazone-based compound, and the binder resin, it is excellent in positive charging property and is simple. Although it is a photoreceptor having a layered structure, it has a high sensitivity and a high surface potential and a small residual potential. Further, since it is a single-layer type photoreceptor, it has a unique effect that it can be easily manufactured with a high yield and is inexpensive.

Claims (4)

[Claims] 1. A photoreceptor having a single layer type photosensitive layer comprising a charge generating material, a charge transporting material and a binder resin, wherein the charge generating material is a perylene compound represented by the following general formula (1). And an organic photoconductor characterized in that the charge transport material is a hydrazone compound represented by the following general formula (2). (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a lower alkyl group or a lower alkoxy group.) (In the formula, R ⁵ represents a hydrogen atom or a lower alkyl group) 2. The organic compound according to claim 1, wherein the perylene compound is N, N'-di (3,5-dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide. Photoconductor. 3. A hydrazone compound is N-methyl-3-
The organophotoreceptor according to claim 1, which is carbazolyl aldehyde N, N-diphenylhydrazone. 4. The photosensitive layer comprises 100 parts by weight of a binder resin,
The organophotoreceptor according to claim 1, containing 2 to 20 parts by weight of a perylene compound and 40 to 110 parts by weight of a hydrazone compound.