JPH02183260A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body high in electrostatic chargeability characteristics and very little in deterioration in sensitivity even at the time of repeated uses and stabilized in potential by electrification by using a specified hydrazone compound as a photoconductive material. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains at least one of the hydrazone compounds represented by formula I in which each of R<1>, R<4>, and R<5> is optionally substituted alkyl, such aralkyl, or the like; R<2> is H, alkyl, or the like; R<3> is H, aryl, or the like; each of R<6> and R<7> is H, optionally substituted alkyl, such aralkyl, or the like; and n is 0 or 1, thus permitting the obtained photosensitive body to be high in sensitivity and durability 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 they have been extensively researched and put into practical use. has been made into 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. Its practical application is increasingly attracting attention because it has advantages such as easy design of photoreceptors for a wide range of wavelengths using a suitable sensitization method.

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 discovered that a novel hydrazone compound represented by the following general formula CI) is effective. This led to the present invention.

(The following is a blank space) RI R2R3 (wherein, R1 is an alkyl group that may have a substituent,
R2 represents hydrogen, an alkyl group, or an alkoxy group; R3 represents hydrogen, an alkyl group, or an aryl group; R4 and R5 may be the same or different and have a substituent. An alkyl group, an aralkyl group, an aryl group that may have hydrogen, an alkyl group, an aralkyl group, an aryl group that may have a hydrogen or a substituent, and R' and R' may be the same or different. represent. However, R6
, except when R7 simultaneously becomes a methyl group.

Further, R' and R' may form a ring. n is 0
Or represents 1. ) Here, specific examples of the substituent R1 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, benzyl group, β-phenylethyl group, p-methylbenzyl group,
Examples include aralkyl groups such as p-methoxybenzyl group and α-naphthylmethyl group, and aryl groups such as phenyl group, naphthyl group, tolyl group, xylyl group, chlorophenyl group, methoxyphenyl group, and methylnaphthyl group.
Specific examples of the substituent R2 include a hydrogen atom, alkyl groups such as a methyl group, ethyl group, and propyl group, and alkoxy groups such as a methoxy group, a nidoxy group, and a propoxy group. Specific examples of the substituent R3 include , a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, an aryl group such as a phenyl group, a tolyl group, a methoxyphenyl group, a chlorophenyl group, and substituents R4,
Specific examples of R5 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, benzyl group, β-phenylethyl group, chlorobenzyl group, methylbenzyl group,
Examples include aralkyl groups such as methoxybenzyl group and α-naphthylmethyl group, and aryl groups such as phenyl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group, tolyl group, xylyl group, and chlorophenyl group.

Further, specific examples of R6 and R' include a hydrogen atom, an alkyl group such as an ethyl group and a propyl group, an aralkyl group such as a benzyl group and a p-methylbenzyl group, a phenyl group, a p-
Aryl groups such as methoxyphenyl can be mentioned.

These hydrazone compounds represented by the general formula [I] can be produced by the methods of the following synthesis examples.

Synthesis Example (Exemplary Compound 3) Hydrazone compound represented by formula (II) 1.45g, 3
．． 3-bis(p-methoxyphenyl)acetaldehyde 1-23 g z and I)-) 30 mg of toluenesulfonic acid hydrate are heated under reflux with 30 ml of toluene for 30 hours. The product was purified by silica gel chromatography (benzene:hexane=1:1) to obtain 1.2 g of compound Nα3. Melting point 197-199°C.

"HNMR (δ, pT)m, CDCl 3) 3.64
(S, 3H) 3.77 (S, 3H) 6.5
-7.5 (m, 29H) Next, hydrazone compounds related to the present invention are illustrated,
It is not limited to these.

(Hereafter, blank space) (Hereafter, blank space) The electrophotographic photoreceptor according to the present invention is obtained by containing one or more types of hydrazone compounds as shown above, 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 mainly composed of 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 added to the photoconductive compound is 0. The ratio is 2 to 10 times, preferably 0.5 to 5 times; if it is less than this, the photoconductive compound will precipitate in the photosensitive layer or on the surface, causing deterioration in adhesion to the support. 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, so it is necessary to add a substance that imparts plasticity to improve these properties. Become.

These substances include phthalates (e.g. DO
P, DBP5DIDP, 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 B10-damine 3B1 acridine red, etc. 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, pyrylium 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.

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

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, 2,4.
Examples include 7-trinitrofluorenone, 1-methyl-4-nitrofluorenone, 2,7-sinitro-3,6-dimethylfluorenone, and the like.

Antioxidants, anti-curl agents, and the like can be added as additives to the low photoreceptor, if necessary.

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 with an applicator onto a polyester film made of aluminum and dried, resulting in a film thickness of 0. 2μ
A film of carrier-generating substance was formed.

Next, a hydrazone compound represented by exemplified compound Nα4,
Polyarylate resin (Unitika U-polymer) and 1;
Mix at a weight ratio of 1 and 10 using dichloroethane as a solvent.
% solution and apply this solution onto the film of the carrier generating substance using an applicator to obtain a dry film thickness of 20 μm.
A carrier transport layer was formed.

The laminated electrophotographic photoreceptor thus prepared was evaluated for electrophotographic characteristics using an electrostatic recording tester (Kawaguchi Gen 5P-428).

Measurement conditions: applied voltage -6KV, static Nα3° As a result, the light half-reduction exposure amount for 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 980 V in the 103rd test, the initial potential in the 103rd test was 950 V, indicating that the potential decreased little due to repetition and was stable, demonstrating 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 Vo (volts) were measured, and the values are shown in Table 1. Furthermore, after repeating the same process 103 times with one cycle of charging and neutralization (irradiation with white light at 400 lux for 1 second), the initial potential Vo (volts) and the light degree halved 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, a carrier transport layer was formed using the exemplary compounds Nα3, Nα4, Nα13, and Nα14 in the same manner as in Example 1, thereby producing 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 an alkyl group, aralkyl group, or aryl group that may have a substituent, and R^2 is hydrogen, an alkyl group, An alkoxy group, R^3 is hydrogen, an alkyl group, or an aryl group, and R^4 and R^5 are an alkyl group or an aralkyl group that may be the same or different and may have a substituent. , an aryl group, and R^6 and R^7 may be the same or different and represent hydrogen, an alkyl group, an aralkyl group, or an aryl group that may have a substituent. However, R^ 6.Except when R^7 is a methyl group at the same time.Also, R^6 and R^7 may form a ring.n represents 0 or 1.)