JPH0561220A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity and satisfactory durability. CONSTITUTION:This electrophotographic sensitive body has an electric charge generating material 2 and an electric charge transferring material 3 on the electric conductive substrate 1 and the electric charge transferring material 3 is a compd. represented by the formula (where each of R1 and R2 is optionally substd. phenyl, optionally substd. naphthyl or an arom. heterocyclic group).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electrophotographic photoreceptors,
The present invention relates to an electrophotographic photoreceptor containing a chalcone compound as a charge transport material.

[0002]

2. Description of the Related Art Conventionally, as a photosensitive layer of an electrophotographic photoreceptor,
Inorganic photoconductive substances such as selenium, selenium-tellurium alloy, and zinc oxide have been widely used, but in recent years, research on electrophotographic photoreceptors using organic photoconductive substances has progressed, and some of them have been put to practical use. ing. Here, most of the photoconductors that have been put to practical use are laminated electrophotographic photoconductors that include a photogenerating layer having a charge-generating layer and a charge-transporting layer that have different functions. The electrophotographic photoconductor is actively designed, which is improved in terms of sensitivity and photoconductor life, which are inferior to those of the human body, and is low cost, and takes advantage of the advantages of organic photoconductive materials such as safety and versatility. It became so.

This type of laminated electrophotographic photoreceptor is generally a charge generating layer made of a charge generating substance such as a pigment or a dye, and a charge transporting layer made of a charge transporting substance such as hydrazone or pyrazoline on a conductive support. Are sequentially formed. Due to the nature of the electron-donating charge transport material, they are of the hole transfer type and have sensitivity when negatively charged on the surface of the photoreceptor. However, with negative charging, the corona discharge used during charging is more unstable than with positive charging, and ozone is about 10 times as much as during positive charging.
There is a problem that nitrogen oxides and the like are generated, and physical deterioration such as adsorption on the surface of the photoconductor or chemical deterioration is easily caused, and further the environment is deteriorated. Still another problem is that the development of the negative charging photoreceptor requires a toner having a positive polarity, but the toner having a positive polarity is difficult to manufacture in view of the triboelectrification series in which the carrier particles of ferromagnetic material are contained. In the component high-resistance magnetic brush developing method, the negatively charged toner / developer is more stable, and the degree of freedom in selection and use conditions is large, and in this respect, the range of application to the positively charged type photoreceptor is wide and advantageous.

Therefore, it has been proposed to use a photoconductor using an organic photoconductive material with a positive charge. For example, when a charge transport layer is laminated on the charge generation layer to form a photoreceptor, the charge transport layer has a large electron transport ability, for example, 2,
Although 4,7-trinitro-9-fluorenone and the like are used, there is a problem that the substance has carcinogenicity and is extremely unsuitable for occupational health.

Further, as a positively charged photoreceptor, US Pat.
No. 615,414 discloses that thiapyrylium salt (charge generating substance) is contained so as to form a eutectic complex with polycarbonate (binder resin). However, this known photoconductor has a drawback that a memory phenomenon is large and a ghost is easily generated.

Therefore, the charge generation layer containing a charge generation substance that generates holes and electrons at the time of light irradiation is used as an upper layer (surface layer), and the charge transport layer containing a charge transport substance having a hole transport ability is used as a lower layer. It is considered that a photoreceptor having a laminated photosensitive layer can be used for positive charging. However, since the layer containing the charge generating substance is formed as the surface layer in the positive charging photoreceptor, at the time of light irradiation, short-wavelength light irradiation such as ultraviolet light irradiation,
Corona discharge, humidity, a charge generating substance vulnerable to external action such as mechanical friction will be present in the vicinity of the surface layer, electrophotographic performance is deteriorated during storage of the photoconductor and during image formation,
The image quality will deteriorate.

In the conventional negative charging photoreceptor having the charge transport layer as the surface layer, the influence of the various external actions is extremely small, and rather the charge transport layer has a function of protecting the lower charge generating layer. is doing.

Therefore, for example, a thin protective layer made of an insulating and transparent resin may be provided to protect the layer containing the charge generating substance from an external action. However, the charge generated during light irradiation is the protective layer. The light irradiation effect is lost due to blocking, and the sensitivity is lowered when the thickness of the protective layer serving as the surface layer is large.

Although various attempts have been made to obtain a photoconductor for positive charging as described above, all of them have many problems to be solved in terms of photosensitivity, memory phenomenon, occupational health and the like.

[0010]

DISCLOSURE OF THE INVENTION The present invention is intended to provide an electrophotographic photoreceptor containing a charge generating substance and a charge transporting substance on a conductive support and having high sensitivity and durability.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted extensive research to solve the above-mentioned problems and, as a result, found a specific group of compounds and completed the present invention.

That is, the constitution of the present invention is an electrophotographic photoreceptor as set forth in the claims.

Next, the compound of the general formula I described in claim 2 of the present specification will be specifically explained.

In the general formula I of the present invention, the substituents of the phenyl group and the naphthyl group in R ₁ and R ₂ are alkyl groups such as methyl group, ethyl group, propyl group, butyl group and t-butyl group. Alkoxy group, for example, methoxy group, ethoxy group and the like, halogen atom, for example, fluorine atom, chlorine atom, bromine atom and the like, trifluoromethyl group and the like as the halogenated alkyl group, alkoxy Examples of the carbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group, further examples include a cyano group and a nitro group, and examples of the heteroaromatic ring include a pyridine ring and a quinoline ring.

Specific examples of the chalcone compound of the general formula I of the present invention are shown in Table 1 in relation to the following general formula I, but not limited thereto.

[0016]

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

[Table 5]

[0022]

[Table 6]

[0023]

[Table 7]

[0024]

[Table 8]

[0025]

[Table 9]

These compounds of general formula I are generally obtained by reacting the following acephenone compounds with the following aldehydes under a basic catalyst.

[0027] (In the formula, R ₁ represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, or a heteroaromatic ring.) R ₂ —CHO (wherein R ₂ is a substituted or unsubstituted phenyl group, A substituted or unsubstituted naphthyl group or a heteroaromatic ring is shown.) Examples of the acetophenone compound include acetophenone, P-methylacetophenone, P-methoxyacetophenone, P-chloroacetophenone, ethylacetylbenzoate, P-cyanoacetophenone, P- Examples of aldehydes include nitroacetophenone.
Benzaldehyde, P-chlorobenzaldehyde, P-
Examples thereof include trifluoromethylbenzaldehyde, P-naphthaldehyde, P-cyanobenzaldehyde, P-butylbenzaldehyde and the like.

Examples of the basic catalyst include sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium acetate, pyridine, piperidine and the like.

Further, as a reaction solvent, ethanol,
N, N-dimethylformamide, tetrahydrofuran,
Examples include dioxane. The reaction temperature is preferably from room temperature to the reflux temperature of each solvent.

Synthesis Example 1 4.4 g (110 mmol) of sodium hydroxide was dissolved in a mixed solvent of 20 g of ethanol / 39.2 g of water, and 10.32 g (86 mmol) of acetophenone was added while cooling with ice, and further benzaldehyde 9.12 g. (86 mm
ol) (however, the temperature at this time is 15 to 36 ° C.) and the reaction is carried out with stirring. The reaction vessel is cooled as it is to precipitate a yellow solid. Then, it is collected by filtration, washed and purified by recrystallization with n-hexane.

The obtained solid had a yield of 10.8 g (yield 6
0.4%) of a yellow solid. The melting point is 57.5.
It was ~ 58 ° C.

Table 2 shows the melting points and elemental analysis results of the compounds obtained as described above.

[0033]

[Table 10]

Next, the structure of the photoconductor of the present invention will be described with reference to the drawings. As the photoconductor, for example, as shown in FIG. 1, a layer containing a charge generating substance and optionally a binder resin on a support 1 (a conductive support or a sheet on which a conductive layer is provided) (charge generating layer). 2) as a lower layer, and a photoreceptor layer 4 having a laminated structure in which a layer (charge transporting layer) 3 containing a charge transporting substance and optionally a binder resin as an upper layer is provided, and as shown in FIG. Protective layer 5 on photoreceptor layer 4
And the one in which a single-layer photosensitive layer 6 containing a charge-generating substance, a charge-transporting substance and, if necessary, a binder resin is provided on a support as shown in FIG. A protective layer may be provided on the photoreceptor layer 6 having the single-layer structure shown in FIG. 3, and an intermediate layer may be provided between the support and the photoreceptor layer.

As the charge generating substance used in the present invention,
If it absorbs visible light and generates free charge,
Both inorganic and organic substances can be used. For example, amorphous selenium, trigonal selenium, selenium-
Inorganic substances such as arsenic alloys, selenium-tellurium alloys, cadmium sulfide, cadmium selenide, cadmium sulfide selenide, mercury sulfide, lead oxide, lead sulfide, and amorphous silicon, or bisazo dyes, polyazo dyes, triarylmethane dyes , Thiazine dye, oxazine dye, xanthene dye, cyanine dye, styryl dye, pyrylium dye, quinacridone dye, indigo dye,
Examples thereof include perylene dyes, polycyclic quinone dyes, bisbenzimidazole dyes, indanthrone dyes, squarylium dyes, anthraquinone dyes, and phthalocyanine dyes.

Examples of the binder resin usable in the photosensitive layer in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin and alkyd. Resin, polycarbonate resin, silicone resin, addition polymerization type resin such as melamine resin, polyaddition type resin, polycondensation type resin,
And a copolymer resin containing two or more of the repeating units of these resins, for example, a vinyl chloride-vinyl acetate copolymer,
In addition to insulating resins such as vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, polymer organic semiconductors such as poly-N-vinylcarbazole can be mentioned.

As the conductive support for supporting the photosensitive layer, a metal plate of aluminum, nickel or the like, a metal drum or a metal foil, a plastic film deposited with aluminum, tin oxide, indium oxide or the like or a conductive substance is used. A coated paper, a film such as plastic, or a drum can be used.

When the photoreceptor according to the present invention is formed with a laminated structure of a charge generation layer and a charge transport layer, that is, in the case of FIGS. 1 and 2, the charge transport material of the present invention is used alone or in a suitable solvent. It is provided by a method in which a material dissolved or dispersed together with an appropriate binder resin is applied and dried. Examples of the solvent used for the charge transport layer include N,
N-dimethylformamide, toluene, xylene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, 1,1,1-trichloroethane, 1,1,2-trichloroethylene, tetrahydrofuran, methylethylketone, cyclohexanone, ethyl acetate, butyl acetate, etc. Can be mentioned. In this charge transport layer, the ratio of the charge transport material contained in the binder resin is 1
The charge transport material is 20 to 200 parts by weight based on 00 parts by weight.

At this time, the film thickness of the charge transport layer is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

The charge-generating layer is formed by vacuum-depositing the charge-generating substance on a conductive support, or by coating a suitable solvent alone or dissolved or dispersed with a suitable binder resin, and drying it to form a charge-transporting layer. It can be similarly formed.

When the charge-generating layer is formed by dispersing the charge-generating substance, the charge-generating substance is preferably a powder having an average particle diameter of 2 μm or less, preferably 1 μm or less. That is, if the particle size is too large, the dispersion in the layer becomes poor, and the particles partially project on the surface and the surface smoothness deteriorates. Toner filming phenomenon tends to occur due to particles being attached. However, if the above particle size is too small, it tends to agglomerate, the resistance of the layer increases, the crystal defects increase and the sensitivity and repeatability deteriorate, or there is a limit on miniaturization, so the average particle The lower limit of the diameter is preferably 0.01 μm.

The charge generation layer can be provided by the following method. That is, the charge generating substance is made into fine particles in a dispersion medium by a ball mill, a homomixer, etc.,
This is a method of applying a binder resin and mixing and dispersing to obtain a dispersion liquid. In this method, if the particles are dispersed under the action of ultrasonic waves, uniform dispersion is possible. In the charge generation layer, the ratio of the charge generation substance contained in the binder resin is 20 to 200 with respect to 100 parts by weight of the binder resin.
It is considered to be part by weight.

The thickness of the charge generation layer formed as described above is preferably 0.1 to 10 μm, particularly preferably 0.5 to 5 μm.

Next, when the photoconductor of the present invention is formed in a single layer structure, that is, in the case of FIG. 3, the ratio of the charge generating substance and the charge transporting substance contained in the binder resin is 100 parts by weight of the binder resin. The charge generation material is 20 to 200 parts by weight, and the charge transport material is 20 to 200 parts by weight. The film thickness of the photoreceptor having this single-layer structure is 7 to 50 μm, more preferably 10 to 30 μm.

The intermediate layer functions as an adhesive layer, a barrier layer, or the like, and in addition to the above binder resin, for example, polyvinyl alcohol, ethyl cellulose,
Resins such as carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, casein, N-alkoxymethyl nylon, etc., as they are, or in which tin oxide, indium oxide, etc. are dispersed A deposited film of aluminum oxide, zinc oxide, silicon oxide, or the like is used. The thickness of the intermediate layer is preferably 1 μm or less.

As the material used for the protective layer, it is suitable to use the above resin as it is or to disperse a low resistance substance such as tin oxide or indium oxide. An organic plasma-polymerized film can also be used, and the organic plasma-polymerized film may optionally contain oxygen, nitrogen, halogen, and Group III or Group V atoms in the periodic table.

[0047]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 5 parts of a bisazo dye represented by the following chemical formula (A), 2.5 parts of butyral resin (Denka butyral resin # 3000-2; manufactured by Denki Kagaku Kogyo) and tetrahydrofuran 92.
Disperse 5 parts in a ball mill for 12 hours, then add tetrahydrofuran to a dispersion concentration of 2% by weight,
The coating liquid was prepared by redispersion. The prepared dispersion liquid was cast and coated on a 100 μm-thick polyester film on which aluminum was vapor-deposited by a doctor blade to form a charge generation layer having a thickness of 1.0 μm after drying.

[0049]

[Chemical 1]

On the charge generation layer thus obtained,
6 parts of an exemplified compound (Compound No. 5) and 10 parts of a polycarbonate resin (Panlite K-1300; manufactured by Teijin Chemicals) Methylphenylsilicone (KF50 100CPS;
(Shin-Etsu Chemical Co., Ltd.) 0.002 parts of a coating solution having a formulation of 0.004 parts and tetrahydrofuran 94 parts was prepared and cast-cast with a docker blade to form a charge-transporting layer having a film thickness after drying of 20.0 μm. A laminated electrophotographic photosensitive member (photosensitive member No. 1) composed of electrodes / charge generating layer / charge transporting layer was prepared.

Examples 2 to 5 Instead of the exemplified compound (Compound No. 5) of Example 1, compound 2, compound No. 3, compound No. 4 in the exemplified compound,
In the same manner as in Example 1 except that the compound No. 6 was used, the photoconductor No. 2, the photoconductor No. 3, the photoconductor 4, the photoconductor No.
5 was produced. Example 6 Instead of 5 parts of the bisazo dye represented by the chemical formula (A) above, a trisazo dye 6 represented by the following chemical formula (B)
A charge generation layer was produced in the same manner as in Example 1 except that the parts were used.

[0052]

[Chemical 2]

On the charge generation layer thus obtained,
A coating liquid consisting of 6 parts of an exemplified compound (Compound No. 5), 10 parts of a polycarbonate resin (Panlite K-1300; manufactured by Teijin Chemicals), 0.002 part of methylphenylsilicone (KF 100CPS; manufactured by Shin-Etsu Chemical), and 94 parts of tetrahydrofuran. And a charge transport layer having a film thickness after drying of 20 μm is formed in the same manner as in Example 1, and a laminated electrophotographic photoreceptor (photosensitive layer) composed of an aluminum electrode / charge generation layer / charge transport layer is formed. Body No. 6) was produced.

Examples 7 to 10 Example 6 Instead of the exemplified compound (Compound No. 5), the compound No. 2, compound No. 3, compound N
O.4, photoconductor No. 7, photoconductor No. 8, photoconductor No. 9, in the same manner as in Example 6 except that compound No. 6 was used.
A photoconductor No. 10 was produced.

Example 11 5 parts of titanyl phthalocyanine (TiPc), polyvinyl butyral resin (S-Rex BLS; Sekisui Chemical Co., Ltd.) 5
Parts and 90 parts of tetrahydrofuran were dispersed in a ball mill for 12 hours, and then tetrahydrofuran was added so as to have a dispersion liquid concentration of 2% by weight and redispersed to prepare a coating liquid. The coating solution prepared in this manner was added to about 10 parts of aluminum.
A 100 μm thick polyester film vapor-deposited to a thickness of 00Å was cast and applied by a doctor blade to form a charge generation layer having a thickness of 0.5 μm after drying.

On the charge generation layer thus obtained,
Exemplified compound (Compound No. 5) 6 parts and polycarbonate resin (Panlite K-1300; manufactured by Teijin Kasei) 10
Parts, and a coating solution having a formulation of 94 parts of tetrahydrofuran, prepared by flow casting with a doctor blade to form a charge transport layer having a thickness of 20.0 μm after drying, and an aluminum electrode / charge generation layer / charge transport layer. A laminated electrophotographic photosensitive member (photosensitive member No. 11) formed of layers was produced.

Examples 12 to 15 Instead of Example 11 (Exemplified Compound No. 5), Compound No. 2, Compound No. 3, Compound No. 4 and Compound No. 6 in the exemplified compounds were used. Except for the above, in the same manner as in Example 11, photoconductor No. 12, photoconductor No. 13, photoconductor No. 14,
A photoconductor No. 15 was prepared.

With respect to the electrophotographic photosensitive member obtained as described above, an electrostatic copying paper test apparatus (Kawaguchi Denki Seisakusho: S
The characteristics were evaluated as follows using P-428).

After applying a corona charge of +6 KV and positively charging, it was left in a dark place for 20 seconds, the surface potential Vo at that time was measured, and then light was applied using a tungsten lamp so that the illuminance on the surface was 40 lux. The amount of exposure required to illuminate Vo at that time was halved by E1 / 2 (lux.se
c) and the surface potential V ₃₀ 30 seconds after the exposure were measured.
The results are shown in Table 3.

[0060]

[Table 11]

[0061]

As described above, the chalcone compound used as the charge transport material according to the present invention can be synthesized relatively easily and has excellent solubility or dispersibility in the binder resin. .. Further, it has an excellent ability to receive the charge generated from the charge generating substance and transport it.

Therefore, the electrophotographic photoreceptor containing the chalcone compound has a high dark decay rate and a high sensitivity.

[Brief description of drawings]

[Figure 1]

[Fig. 2]

FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor of the present invention.

FIG. 4 is an infrared absorption spectrum diagram of Compound No. 5 used in Example 1.

[Explanation of symbols]

 1 Support 2 Charge Generation Layer 3 Charge Transport Layer 4 Photoconductor Layer (Layered Structure) 5 Protective Layer 6 Photoconductor Layer (Carbon Layer Structure)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Yoshikawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Co., Ltd. (72) Inventor Tetsuro Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Shares In Ricoh Company (72) Inventor Masakatsu Shimoda 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (2)

[Claims] 1. An electrophotographic photoreceptor containing a charge generating substance and a charge transporting substance on a conductive support, wherein the charge transporting substance is a chalcone compound. 2. The electrophotographic photoreceptor according to claim 1, wherein the chalcone compound is represented by the following general formula I. However, R ₁ and R ₂ are substituted or unsubstituted phenyl groups,
It represents a substituted or unsubstituted naphthyl group or a heteroaromatic ring group.