JPH02186357A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability of an electrophotographic sensitive body by using a specified hydrazone compound for the sensitive body. CONSTITUTION:The photosensitive body contains at least one of the hydrazone compounds represented by formula I in which R<1> is a heterocyclic group; R<2> is H, alkyl, or alkoxy; R<3> is H, alkyl, or aryl; each of R<4> and R<5> is alkyl, aralkyl, or aryl; and each of R<6> and R<7> is alkyl or aryl. The photosensitive body is manufactured by dissolving or dispersing the hydrazone compound in a proper solvent together with various additives in accordance with the form of the photosensitive body, coating a conductive substrate with the obtained coating material, and drying it, thus permitting the obtained photosensitive body to be enhanced in electrostatic chargeable characteristics, very little in deterioration of sensitivity at the time of repeated uses, and stabilized in potential by electrification.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to an electrophotographic photoreceptor containing a novel hydrazone compound.

(B) Prior art and problems Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and silicon have been known to be used as electrophotographic photoreceptors, and have been extensively studied and put into practical use. has been done. In recent years, in contrast to these inorganic materials, research into organic photoconductive materials has progressed actively, and some have been put into practical use as electrophotographic photoreceptors.

Generally speaking, inorganic materials have problems such as thermal stability, deterioration of properties due to crystallization, and manufacturing difficulties in selenium photoreceptors, and moisture resistance, durability, and industrial difficulties in the case of cadmium sulfide. In contrast, organic materials have good film-forming properties, excellent flexibility, light weight, and transparency. Since it has advantages such as the ease of designing a photoreceptor for a wide range of wavelengths by using an appropriate sensitization method, its practical application is gradually attracting attention.

Incidentally, photoreceptors used in electrophotography are generally required to have the following basic properties.

That is, (1) the charging property is high against corona discharge in the dark, (2) there is little leakage (dark decay) of the obtained charged charge in the dark, and (3) the charged charge is reduced by light irradiation. (4) The residual charge after light irradiation is small.

However, to date, much research has been conducted on photoconductive polymers such as polyvinylcarbazole as organic photoconductive materials, but these do not necessarily have sufficient film properties, flexibility, or adhesive properties, and as mentioned above, It is difficult to say that the photoconductor has sufficient basic properties as a photoreceptor.

On the other hand, with regard to organic low-molecular photoconductive compounds, it is possible to obtain photoreceptors with excellent film properties, adhesion, flexibility, and other mechanical strengths by selecting the binder used to form the photoreceptor. Although possible, it is difficult to find suitable compounds that can retain the properties of high sensitivity.

In order to improve this point, organic photoreceptors having higher sensitivity characteristics have been developed by assigning the carrier generation function and the carrier transport function to different substances. A feature of this kind of photoreceptor, which is called a functionally separated type, is that materials suitable for each function can be selected from a wide range, and a photoreceptor with arbitrary performance can be easily created, which has led to a lot of research. has been progressing.

(C) Purpose of the Invention As mentioned above, various improvements have been made in the production of electrophotographic photoreceptors, but the basic properties required for photoreceptors as listed above, high durability, etc. We still haven't been able to find anything that satisfies our needs.

An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability. In particular, it is an object of the present invention to provide a photoreceptor that has high charging characteristics, exhibits almost no decrease in sensitivity even after repeated use, and has a stable charging potential.

(D) Structure of the Invention As a result of research into photoconductive substances with high sensitivity and high durability, the present inventors found that a novel hydrazone compound represented by the following general formula (1) is effective. Heading This invention has led to this invention.

R1g2 ll3 2.7/ (In the formula, R1 is a heterocycle, R2 is hydrogen, an alkyl group, or an alkoxy group, R3 is hydrogen, an alkyl group, or an aryl group, and R4 and R5 are the same or different) R6R7 may be the same or different and hydrogen, an alkyl group, aralkyl group, or aryl group that may have a substituent may be an alkyl group, an aralkyl group, or an aryl group that may have a substituent. (R6 and Rff may form a ring. n represents 0 or 1.) Specific examples of R1 include a pyridine ring, a quinoline ring, a thiophene ring, a benzothiophene ring, etc. Specific examples of the substituent Rz include a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, and a propyl group, and an alkoxy group such as a methoxy group, an ethoxy group, and a propoxy group. Specific examples include hydrogen atoms, alkyl groups such as methyl groups, ethyl groups, and propyl groups, and aryl groups such as phenyl groups, tolyl groups, methoxyphenyl groups, and chlorophenyl groups.
, Specific examples of R8 and 1- include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, benzyl group, β-
Aralkyl groups such as phenylethyl group, chlorobenzyl group, methylbenzyl group, methoxybenzyl group, α-naphthylmethyl group, phenyl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group, tolyl group, xylyl group,
Aryl groups such as chloropher groups can be mentioned.

Specific examples of R'1 and R1 include a hydrogen atom, a methyl group,
Examples include alkyl groups such as ethyl groups, aralkyl groups such as benzyl groups and p-methylbenzyl groups, and aryl groups such as phenyl groups and p-methoxyphenyl groups.

These hydrazone compounds represented by formula (I) are:
For example, a compound represented by the following formula (n) and the general formula (D
It can be synthesized by condensation of aldehydes represented by I).

(In the formula, R1-R7 and n are the same as those in general formula (13).) Next, hydrazone compounds related to the present invention are illustrated,
It is not limited to these.

(Left below) L CHi CH3-C! 'l13 The electrophotographic photoreceptor according to the present invention is obtained by containing one or more of the above-mentioned hydrazone compounds, and has excellent performance.

Various methods are known for using these hydrazone compounds as electrophotographic photoreceptors.

For example, a photoreceptor comprising a hydrazone compound and a sensitizing dye, dissolved or dispersed in a binder resin with the addition of a chemical sensitizer or an electron-withdrawing compound as necessary, on a conductive support. , or in the form of a laminated structure consisting of a carrier generation layer and a carrier transport layer, on a conductive support.
On a carrier generation layer provided mainly with a carrier generation substance with high carrier generation efficiency, such as a dye or a pigment,
A photoreceptor formed by laminating the present hydrazone compound dissolved or dispersed in a binder resin with the addition of a chemical sensitizer or an electron-withdrawing compound as necessary as a carrier transport layer, and its carrier generation layer. There is a photoreceptor in which a carrier transport layer and a carrier transport layer are laminated inversely on a conductive support, but it can be applied to either case.

As a support for producing a photoreceptor using the compound of the present invention, a metal drum, a metal plate, paper treated with electrical conductivity, a plastic film, or a belt-like support is used.

Various film-forming binder resins can be used to form the photosensitive layer on these supports depending on the field of use. For example, for use in photoreceptors for copying, polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, vinyl acetate/crotonic acid copolymer resin, polyphenylene oxide resin, polyester resin, alkyd resin, polyarylate resin, acrylic resin, methacrylic resin , phenoxy resin, etc. Among these, polystyrene resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polyarylate resins, phenol resins, and the like have excellent potential characteristics as photoreceptors.

In addition, these resins may be used alone or as a copolymer.
A mixture of more than one species can be used.

The amount of these binder resins to be added to the photoconductive compound is 0.2 to 10 times the weight ratio, preferably 5 to 5 times, and if it is less than this, the photoconductive compound is precipitated in or on the surface of the photosensitive layer, causing deterioration in adhesion to the support, and when the amount increases, sensitivity decreases.

Next, some of the film-forming binder resins used are rigid and weak in mechanical strength such as tension, bending, and compression, and in order to improve these properties, a substance that imparts plasticity may be added. is also required.

These substances include phthalates (e.g. DO
PSDBP, DIDP, etc.) phosphate esters (e.g. T
(CP, TOP, etc.), sebacic acid ester, adipic acid ester, nitrile rubber, chlorinated hydrocarbons, etc. When adding these plasticity imparting substances, the proportion thereof is preferably 20% or less by weight relative to the binder resin, since adding more than necessary will result in deterioration of the potential characteristics.

Next, the sensitizing dyes added to the photosensitive layer include triphenylmethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, rhodamine B, rhodamine 3B1, and acridine red. xanthene dye represented by B, etc.; acridine dye represented by Acridine Orange 2G, Acridine Orange R1 Flaveosin, etc.; thiazine dye represented by Methylene Blue, Methylene Green; Other dyes include cyanine dyes, styryl dyes, biryllium salts, thiapyrylium salts, and squareium salt dyes.

Photoconductive pigments that generate carriers with extremely high efficiency through light absorption in the photosensitive layer include phthalocyanine pigments such as metal-free phthalocyanine, phthalocyanine containing various metals or metal compounds, perylene imide, and perylene acid anhydride. These include perylene pigments such as quinacridone pigments, anthraquinone pigments, and azo pigments.

Among these pigments, those using bisazo pigments, trisazo pigments, and phthalocyanine pigments, which have particularly high carrier generation efficiency, provide high sensitivity and provide excellent electronic photoreceptors.

Further, although the dye added to the photosensitive layer described above can be used alone as a carrier-generating substance, carriers may be generated with even higher efficiency by coexisting with a pigment. Examples of inorganic photoconductive materials include selenium, selenium tellurium alloy, cadmium sulfide, zinc sulfide, and amorphous silicon.

In addition to the sensitizers mentioned above (so-called spectral sensitizers), it is also possible to add sensitizers (so-called chemical sensitizers) for the purpose of improving sensitivity.

Examples of the sensitizer include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4-chloro-
m-Cresol, p-chlorobenzoylacetanilide, N,N-diethylbarbital acid, 3-(β-oxyethyl)-2-phenylimino-thiazolidone, malonic dianilide, 3.5.3-. Examples include 5''-tetrachloromalonic acid dianilide, α-naphthol, and p-nitrobenzoic acid.

Further, it is also possible to add a certain type of electron-withdrawing compound as a sensitizer that forms a charge transfer complex with the hydrazone compound of the present invention and further increases the sensitizing effect.

Examples of the electron-withdrawing substance include 1-chloroanthraquinone, 1-nitroanthraquinone, 2,3-dichloro-naphthoquinone, 3,3-dinitrobenzophenone,
4-nitrobenzalmalonenitrile phthalic anhydride, 3-
(α-cyano-p-nitrobenzal)phthalide, 2,
Examples include 4,7-trinitrofluorenone, 1-methyl-4-nitrofluorenone, 2,7-sinitro-3,6-simethylfluorenone, and the like.

Other additives such as antioxidants and anti-curl agents may be added to the photoreceptor as required.

The hydrazone compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additive substances mentioned above depending on the form of the photoreceptor, and the coating solution is applied onto the conductive support described above.
Dry to produce a photoreceptor.

Coating solvents include halogenated hydrocarbons such as chloroform, dichloroethane, trichloroethane, and trichloroethylene, aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, dioxane, tetrahydrofuran, methyl cellosolve, dimethyl cellosolve,
Solvents such as methyl cellosolve acetate alone or in combination
A mixed solvent of more than one species or a solvent such as alcohols, acetonitrile, N,N-dimethylformamide, and methyl ethyl ketone may be added if necessary.

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

(Left below) 1 part by weight of the pigment shown in Example 1, 1 part by weight of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.), and 1 part by weight of tetrahydrofuran.
00 parts by weight and dispersed with glass beads for 2 hours using a paint conditioner device. The pigment dispersion thus obtained was applied onto a polyester film deposited with aluminum using an applicator and dried to form a film of carrier-generating material having a thickness of about 0.2 μm.

Next, a hydrazone compound represented by Exemplary Compound No. 1 was mixed with a polyarylate resin (Unitika U-Polymer) in a 1:1 ratio.
Mix at a weight ratio of 10% with dichloroethane as a solvent.
A solution was prepared, and this solution was applied onto the film of the carrier generating substance using an applicator to form a gear transport layer having a dry film thickness of 20 μm.

The laminated electrophotographic photoreceptor created in this way was tested on an electrostatic recording test device! Electrophotographic characteristics were evaluated using i (5P-428 manufactured by Kawaguchi Denki).

Measurement conditions: Applied voltage -5KV, static height 3° As a result, the light half-reduction exposure to white light during charging is 2
．． It showed an extremely high sensitivity value of 2 lux·sec.

Furthermore, the same device was used to evaluate repeated use.

When the change in charging potential due to 103 repetitions was calculated, 1
In contrast to the initial potential of 890 V in the 103rd test, the initial potential in the 103rd test was 870 V, indicating that the potential decreased little due to repetition and was stable, showing excellent characteristics.

Examples 2 to 5 Laminated photoreceptors were prepared in the same manner as in Example 1, except that the hydrazone compounds shown in Table 1 were used in place of the hydrazone compounds used in Example 1, and the same measurement conditions as in Example 1 were carried out. The half-light exposure E1/2 (lux seconds) and the initial potential V'o (volts) were measured, and the values are shown in Table 1.

Furthermore, static electricity is removed (static electricity removal light: 400 lux x 1 with white light)
After repeating the same process 10' times with 1 second irradiation), the initial potential Vo (volt) and the light half-reduced exposure amount E1
/2 is shown in Table 1.

(Margin below) Examples 6-9 A bisazo pigment having the following structure was used as a charge generating substance.

That is, 1 part by weight of this pigment, 1 part by weight of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.), and 1 part by weight of tetrahydrofuran.
00 parts by weight and dispersed with glass beads for 2 hours using a paint conditioner device. The pigment dispersion thus obtained was applied onto the same support as in Example 1 using an applicator to form a carrier generation layer. The thickness of this thin film was about 0.2μ.

Next, Example 1 was prepared using the exemplified compounds shown in Table 2.
A carrier transport layer was formed in the same manner as above to create a laminated photoreceptor. This photoreceptor was evaluated under the same measurement conditions as in Example 1. The results are shown in Table 2.

(Margin below)

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a hydrazone compound represented by the following general formula [I] on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[I] (In the formula, R^1 is a heterocycle, R^2 is hydrogen, an alkyl group, or an alkoxy group, and R^3 is hydrogen, an alkyl group, or an aryl group. , R^4 and R^5 may be the same or different, and represent an alkyl group, aralkyl group, or aryl group that may have a substituent, and R^6 and R^7 are the same It represents hydrogen, an alkyl group, an aralkyl group, or an aryl group which may have a substituent, which may be present or different.Also, R^6 and R^7 may form a ring. n represents 0 or 1.)