JPH04101153A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body high in sensitivity and durability by forming a photosensitive layer containing a specified carbazole compound on a conductive substrate. CONSTITUTION:The photosensitive layer formed on the conductive substrate contains the carbazole compound represented by formula I in which each of R and R' is lower alkyl, allyl, methallyl, optionally substituted benzyl, or optionally substituted aryl; and A is optionally substituted aryl. The photosensitive body is manufactured by dissolving or dispersing such a carbazole compound into a proper solvent together with various additives selected in accordance with the kind of the photosensitive body, coating the conductive substrate, and drying it, thus permitting the obtained electrophotographic sensitive body to have high sensitivity and high durability.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a carbazole compound.

<Prior Art> Conventionally, in electrophotographic technology, inorganic substances such as selenium, cadmium sulfide, amorphous silicon, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors.
In recent years, much research has been conducted on the use of organic photoconductive materials as electrophotographic photoreceptors. Here, the basic properties required for an electrophotographic photoreceptor are (1) high chargeability due to corona discharge in the dark;

(2) The resulting corona charge has little attenuation in the dark.

(3) Charges are quickly dissipated by light irradiation.

(4) There is little residual charge after irradiation with light.

(5) Increase in residual potential and decrease in initial potential due to repeated use are small.

(6) Changes in the surface of the photoreceptor and electrophotographic characteristics due to temperature and humidity are small.

Conventional inorganic electrophotographic photoreceptors such as selenium and cadmium sulfide have basic properties that meet the requirements for photoreceptors, but there are manufacturing problems such as high toxicity and difficult film formation. , has disadvantages such as poor plasticity and high manufacturing cost. Looking further into the future,
Due to the depletion of resources, production is limited, and also from the viewpoint of pollution due to toxicity, it is desired to use photoreceptors made of organic materials instead of inorganic materials. In view of these points, research on electrophotographic photoreceptors made of organic materials has been actively conducted in recent years, and as a result, electrophotographic photoreceptors using various organic materials have been proposed and put into practical use. There is also.

In general, compared to inorganic materials, organic materials have better transparency, are lighter in weight, are easier to form into films, and have both positive and negative chargeability, making them suitable for use in the manufacture of photoreceptors. It also has the advantage of being easy to use.

<Problems to be Solved by the Invention> Typical organic electrophotographic photoreceptors that have been proposed so far include, for example, polyvinylcarbazole and its derivatives, but these do not necessarily have film properties or flexibility. ,
In addition, polyvinyl carbazole sensitized with pyrylium salt dye (Japanese Patent Publication No. 4825658), polyvinyl carbazole and 2
There are improved versions such as those sensitized with 4.7-trinitrofluorenone (US Pat. No. 3,484,237), but
A photoreceptor that satisfies the above-mentioned requirements for basic properties, mechanical strength, high durability, etc. has not yet been obtained.

An object of the invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability.

Means for Solving the Problems As a result of research into photoconductive materials with high sensitivity and high durability for the above-mentioned purposes, the present inventors have found that a carbazole compound represented by the following general formula is effective. This discovery led to the present invention.

That is, the present invention provides the following general formula (■) on a conductive support.
Provided is an electrophotographic photoreceptor characterized in that a photosensitive layer containing a carbazole compound represented by the following is formed.

R' (In the formula, R and R' represent a lower alkyl group, an allyl group, a methallyl group, a benzyl group that may contain a substituent, an aryl group that may contain a substituent, and A is an aryl group that may contain a substituent. Among the carbazole compounds represented by the above general formula (I), the carbazole compound represented by the following general formula (old) is particularly excellent in terms of sensitivity and stability.

(In the formula, a and b are hydrogen, lower alkyl, lower alkokene,
Represents halogen, R+ is lower alkyl group, allyl group,
Represents a methallyl group, a pencil group which may contain a substituent, and an aryl group which may contain a substituent. ) Further, in the electrophotographic photoreceptor, the photosensitive layer preferably contains a carrier transfer substance and a carrier generation substance,
Preferably, the carbazole compound is used as the carrier transfer substance.

The carbazole compound of general formula (I) according to the present invention can be synthesized through the following synthesis process.

(In the above reaction formula,・It is a Mayer reaction and proceeds easily at an internal temperature of around 80°C.Reaction (Ic) is a Uititech reaction, and it proceeds easily in DMF or DMSO, usually at room temperature.In this way, the carbazole compound of the present invention can be easily synthesized. As a specific example of the carbazole compound represented by the general formula (I), for example, Table IVC below
The carbazole compounds of the present invention are not limited thereto.

Table 1 The electrophotographic photoreceptor of the present invention contains 1 of the above carbazole compounds.
It can be obtained by incorporating different types or two or more types into the photosensitive layer, and has extremely excellent performance.

Additionally, hydrazone compounds (e.g. P-N, N-diphenylaminobenzaldehyde-N, N-diphenylhydrazone, P-N, N-cypendylaminopenzaldehyde-N, N-diphenylhydrazone) or 1,8-butadiene compounds ( For example, 1(P-diethylaminophenyl)-
4,4-diphenyl-1,3-furidiene, 1,1-di(P dimethoxyphenyl) 414' phenyl 1
．． 3-phridien) or pyrazoline compounds (e.g. Eva I-
A photoreceptor having extremely excellent performance can also be obtained by mixing a compound such as (P-diethylaminophenyl)-3°5-diphenylpyrazoline).

Various methods are known for using these carbazole compounds as electrophotographic photoreceptors. In the form of a photoreceptor formed by dissolving or decomposing a binder resin on a conductive support, or in the form of a laminated structure consisting of a carrier generation layer with high charge carrier generation efficiency and a carrier transfer layer, conductive The present cal-gusol compound is added to a carrier-generating layer mainly composed of a sensitizing dye or a pigment such as an azo pigment on a support, and if necessary, a chemical sensitizer or an electron-withdrawing compound is added. There is a photoreceptor in which a carrier transport layer is formed by dissolving or decomposing a binder, but it can be applied to either case.

Photoreceptors may be prepared using the compounds of the present invention with the aid of polymeric film-forming binders on supports such as metal drums, metal plates, conductively treated paper, or plastic films. Make it into a film.

In this case, in order to further increase the sensitivity, it is desirable to add a sensitizer or a substance that imparts plasticity to the polymerizable film-forming binder as described below to form a uniform photoreceptor film.

Various types of polymerizable film-forming binders can be used depending on the field of use.

In other words, in the field of photoreceptors for copiers or printers, polystyrene resin, polyvinyl acetal resin,
Preferred are polysulfone resins, polycarbonate resins, polyphenylene oxide resins, polyester resins, alkyd resins, polyarylate resins, and the like. These may be used alone or in combination of two or more. Among them, polystyrene.

Resins such as polycarbonate, polyarylate, and polyphenylene oxide have a volume resistivity of 1013Ω or more, and also have excellent film properties, potential characteristics, and the like.

The amount of these binders to be added to the carbazole compound of the present invention is in a weight ratio of 0.2 to 20 times, preferably in the range of 0.5 to 5 times. The drawback is that it may precipitate from the body surface, and if it is 5 times or more, it may cause a significant decrease in sensitivity.

Especially alkaline binders are required for use in printing plates. An alkaline binder is an acidic group that is soluble in water or an alcoholic alkaline solvent (including mixed systems), such as an acid anhydride group, a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group, or a sulfonimide group. It is a polymer substance with groups.

It is preferable that these alkaline binders usually have a high acid value of 100 or more. A binder resin with a high acid value easily dissolves or swells in an alkaline solvent.

These binder resins include, for example, styrene maleic anhydride copolymer, vinyl acetate maleic anhydride copolymer, vinyl acetate maleic anhydride copolymer, vinyl acetate maleic anhydride copolymer,
These include crotonic acid copolymer, methacrylic acid/methacrylic acid ester copolymer, phenolic resin, methacrylic acid/styrene, methacrylic acid ester copolymer, and the like. Further, the proportion of these resins added to the photoconductive organic substance may be approximately the same as in the case of a photoreceptor for a copying machine.

Next, the sensitizing dyes added to the photosensitive layer are methyl violet and crystal violet.

Triphenylmethane dyes such as night blue and Victoria blue, acridine dyes such as erythrosine, rhodamine B, rhodamine 3R, and acridine orange flabeosin, thiazine dyes such as methylene blue and methylene green, and capri blue. ,
Oxazine dyes such as Meldra Plue, other cyanine dyes, styryl dyes, pyrylium salt dyes,
Examples include thiobilylium salt dyes.

Photoconductive pigments that generate charge carriers with extremely high efficiency through light absorption in the photosensitive layer include metal phthalocyanine, metal-free phthalocyanine, 7-thalocyanine pigments such as halogenated metal-free phthalocyanine, perylene imide, and perylene acid anhydride. There are perylene pigments such as, azo pigments such as bisazo pigments and trisazo pigments, and other quinacridone pigments and anthraquinone pigments. In particular, those using metal-free phthalodianiline pigments, titalonium phthalocyanine pigments, bisazo pigments based on fluorene rings and florenone rings, bisazo pigments based on aromatic amines, and trisazo pigments as pigments that generate charge carriers. To provide an excellent electrophotographic photoreceptor with high sensitivity.

The dyes mentioned above may also be used as charge carrier generating substances. These dyes may be used alone, but in many cases, charge carriers can be generated with even higher efficiency by coexisting with a pigment.

In addition to the spectral sensitizers listed above, it is sometimes necessary to add various chemical substances to prevent increases in residual potential, decreases in potential, and decreases in sensitivity due to repeated use. . These added substances include 1-chloroanthraquinone, benzoquinone, 2,3-dichloronaphthoquinone, naphthoquinone, 4,4'-dinitrobenzophenone, 4,4'-dichlorobenzophenone, 4-nitrobenzophenone, and 4-nitrobenzal. Malondinitrile.

α-cyano-β=(P-cyanophenyl)ethyl acrylate, 9-anthracenylmethylmalondinitrile, 1
Examples include -cyano-1-(P-nitrophenyl)-2-(P-chlorophenyl)ethylene and 2°7-sinitrofluorenone. In addition, antioxidants are added as additives to the photoreceptor.

An anti-curl agent, a leveling agent, etc. can be added as necessary.

The carbazole compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives mentioned above depending on the form of the photoreceptor, and the coating solution is applied onto the conductive support described above and dried. A photoreceptor is manufactured.

As a coating solvent, aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, a single solvent or a mixture of two or more solvents such as dioxane, dimethoxyethane, dimethylformamide, and methylene chloride, or alcohols as necessary. , acetonitrile, methyl ethyl ketone, and the like can be further used.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these in any way.

<Example> Examples 1 to 4 An aluminum-deposited polyester film (thickness: 75 μm) was used as a support, and a bisazo pigment represented by the following structural formula was coated with polyvinyl butyral resin (Eslec B manufactured by Nissin Chemical Industry Co., Ltd.) on the support. Add the same amount by weight of the resin to the dissolved l','o T HF solution, and then disperse for about 1 hour in a paint conditioner (manufactured by Red Devil Co., Ltd.) together with glass beads with a diameter of 1 mm, using the Dr. Plaid method. It was coated and dried. The film thickness after drying was 0.2 μm.

Exemplary compound N of the present invention is applied on this pigment layer (charge generation layer).
A 12% solution prepared by dissolving 1 g of each carbazole compound of 2 N113 N15 ml 5 and 1.2 g of polyarylate resin (V Polymer manufactured by Unitika) in methylene chloride was applied using a squeegee doctor, and a dry film thickness of 18
μm resin-carbazole compound solid solution phase (charge transfer layer)
It was created.

The electrophotographic properties of the thus produced laminated electrophotographic photoreceptor were evaluated using an electrostatic recording paper tester (5P-428 manufactured by Kawaguchi Denki Co., Ltd.).

The exposure amount El 00 (lux seconds) and initial potential vO (-bold) required to attenuate from -700 to -100 V by white light irradiation (irradiation light -5 tux) were measured, and the values are shown in Table 2. .Furthermore, the same device was used to apply and eliminate static electricity (
After performing the same operation 10,000 times with one cycle of static elimination light (irradiated with white light at 400 lux for 01 seconds), the initial potential vO (-volt) and Eloo (lux seconds) were measured, and the changes in VQ and Eloo were measured. I looked into it. Further, as a comparative example, an electrophotographic photoreceptor was prepared in exactly the same manner except that a carbazole compound having the structure shown below was used instead of the carbazole compound of the present invention to form a charge transfer layer. In addition, the electrophotographic properties of this photoreceptor were measured in the same manner, and the values are shown in Table 2.

2H5 Table 2 with blank spaces below 2 Repetitive characteristics of each photoreceptor Previously The potential rise was extremely large and measurement became impossible after about the 50th repetition.

The above results show that the electrophotographic photoreceptor containing the carbazole compound represented by the general formula CI) of the present invention has good sensitivity and high repeatability.

Example 5 A multilayer electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that Exemplified Compound N123 was used in place of Exemplified Compound No. 2, and the same characteristics evaluations as in Example 1 were performed. The results were as shown below.

□□-" From the above results, the electrophotographic photoreceptor containing the carbazole compound represented by the general formula ([T) of the present invention is more effective than the electrophotographic photoreceptor containing the carbazole compound represented by the general formula (I). It can be seen that it is stable with high sensitivity and high repeatability.

Example 6 On an aluminum-deposited polyester film, 0.4 g of VCx type metal-free phthalocyanine (manufactured by Dainippon Ink Co., Ltd.) 7 Stogen Blue 8120) was mixed with 0.3 g of vinyl chloride vinegar-picopolymer resin (Nislex M, manufactured by Block Chemical Co., Ltd.) was added to 30 mL of an ethyl acetate solution, dispersed in a paint conditioner for about 20 minutes, and applied by the Doctor Plaid method to form a charge generation layer to a dry film thickness of 0.477 m.

A polyarylate layer containing a carbazole compound (melting point 1685 to 1700°C) of Exemplified Compound No. 27 was laminated on this charge generation layer to prepare a photoreceptor having a two-layer structure. The energy required (E2) and the initial potential (V) were determined by reducing the 780 nm spectral sensitivity of this photoreceptor by half, and found that VO = 820 volts.

It was a highly sensitive photoreceptor with EV2=025 (erg/yield) and highly chargeable. In addition, a laser printer (WD-580P) manufactured by Sharp Corporation was modified, the present photoreceptor was attached to the drum portion, and continuous copying was performed 10,000 times to examine the degree of decrease in initial potential and sensitivity. The result is V
O=750 (volts).

E,! I/j=0.25 (erg/shu), and no significant change in sensitivity was observed compared to the first test.

Incidentally, the decrease in the initial potential is mainly due to thinning of the photosensitive layer, and taking this into consideration, it is considered that there is almost no decrease in the initial potential due to repetition.

Example 7 Styrene: ethyl methacrylate: methacrylic acid (styrene: ethyl methacrylate) = 32 I weight ratio acid value = 170) and exemplified compound part 3 (melting point 1360~ 137.5°C) at a weight ratio of 2:I, and 5% of the exemplified compound and 4-(P-diethylaminophenyl)-
2,6-cyphenylthiopyrylium perchlorate (
A thiopyrylium salt dye) was added to each of the exemplified compounds at a ratio of 0.5% to make a 10% dioxane solution as a whole, and this solution was applied and dried using a squeegee doctor to create a single-layer photoreceptor with a film thickness of 7 μm. . The electrophotographic characteristics of the thus prepared photoreceptor were evaluated using the aforementioned 5P-428.

Evaluation conditions: applied voltage -6KV, static -3 initial potential 460 (volts), light half-decreased exposure amount 12 (lux seconds), the photoreceptor was visualized with a developer (toner), and then an alkaline processing liquid (3 % triethanolamine, 10%
Ammonium carbonate and 20% average molecular weight 190-210
When treated with polyethylene glycol), the toner-free areas were easily eluted, and by washing with water containing sodium silicate, a printing original plate could be easily prepared.

It was found that when offset printing was performed using this original plate, it could withstand printing of about 100,000 sheets.

The optimum exposure amount for obtaining a visible toner image was 500 lux for 1 second. In addition, when creating the original printing plate, direct plate making was performed without using any base material.

<Effects of the Invention> According to the present invention, an electrophotographic photoreceptor having high sensitivity and high durability can be obtained.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor characterized in that a photosensitive layer containing a carbazole compound represented by the following general formula (I) is formed on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, R and R' are lower alkyl groups, allyl groups, methallyl groups, benzyl groups that may contain substituents, and aryl groups that may contain substituents. 2. The carbazole compound represented by the general formula (I) is a carbazole compound represented by the following general formula (II). The electrophotographic photoreceptor according to claim 1. ▲
There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (In the formula, a and b are hydrogen, lower alkyl, lower alkoxy,
represents a halogen, R' is a lower alkyl group, an allyl group,
Represents a methallyl group, a benzyl group which may contain a substituent, and an aryl group which may contain a substituent. 3. The photosensitive layer comprises a carrier transfer substance and a carrier generation substance, and a carbazole compound represented by the general formula (I) is used as the carrier transfer substance. electrophotographic photoreceptor.