JPH02184856A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To stabilize potential by electrification without lowering sensitivity even after repeated uses by forming a photosensitive layer containing a specified hydrazone compound on a conductive substrate. CONSTITUTION:The photosensitive layer formed on the conductive substrate contains one of the hydrazone compounds represented by formula I in which A is an aromatic ring or a hetero ring; R<1> is H, alkyl, or aryl; R<2> is optionally substituted alkyl, such aralkyl, or such aryl; each of R<3> and R<4> is H, optionally substituted alkyl, such aralkyl, or such aryl, each optionally same or different, or each may combine with each other to form a ring; m is 1 or 2; and n is 0 or 1, thus permitting sensitivity to be not lowered even after repeated uses and stable potential by electrification to be obtained.

Description

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

CB) 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 these materials have been extensively researched and have not been put into practical use. ing. 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.

By the way, the photoreceptor used in electrophotography technology is -
The following basic characteristics are required for boat fishing.

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 substances, but these do not necessarily have sufficient film properties, scorbability, 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 mechanical strength such as filmability, adhesion, and sinterability by selecting the binder used for forming the photoreceptor. Although possible, it is difficult to find suitable compounds that can retain the properties of high sensitivity.

In order to improve these points, organic photoreceptors having higher sensitivity characteristics have been developed by assigning carrier generation and carrier transport functions to different substances. Functional part B
The characteristics of such photoreceptors, which are called molds, are that materials suitable for each function can be selected from a wide range, and many studies have been conducted because photoreceptors with arbitrary performance can be easily created. It 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.

(In the formula, A represents an aromatic ring or a heterocycle; R1 represents hydrogen, an alkyl group, or an aryl group; 12 represents an alkyl group, an aralkyl group, or an aryl group that may have a substituent; R3, R
4 may be the same or different and represents hydrogen, an alkyl group which may have a substituent, an aralkyl group, or an aryl group. Further, R5 and R4 may form a ring. m represents 1 or 2, and n represents 0 or l. ) Specific examples of A include aromatic rings such as a benzene ring and naphthalene ring, and heterocycles such as a carbazole ring and a phenothiazine ring.

Specific examples of the substituent R1 include a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, and a propyl group, an aryl group such as a phenyl/L' group, an )IJ group, a methoxyphenyl group, and a chlorophenyl group. Specific examples of the substituent R2 include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, benzyl group, β-phenylethyl group, chlorobenzyl group, methylbenzyl group, methoxybenzyl group, a- Aralkyl groups such as 7termethyl groups, phenyl groups, naphthyl groups, methoxyphenyl i, -r
-) Aryl groups such as xyphenyl group, tolyl group, xylyl group, and chlorophenyl group.

Specific examples of 几3 and R4 include a hydrogen atom, an alkyl group such as a methyl group and an ethyl group, a 7-ralkyl group such as a benzyl 21S, I)-1 thylbenzyl group, an aryl group such as a phenyl group and a p-methoxyphenyl group. can be mentioned.

These hydrazone compounds represented by the general formula (I) can be produced by the following synthesis examples.

Synthesis Example (Exemplary Compound A (31)) 1.56F of the hydrazone compound represented by formula (n) and 0.50P of methallyl chloride were dissolved in DMFIO-, and 1.12F of potassium-1-butoxide was added at room temperature.

After 4 hours, the reaction mixture was poured into water to remove the precipitate. Recrystallization from acetonitrile yielded 1.12 g of compound (3). Melting point 127.0-128.0℃ NM⇠(t*
ppm*DMSO) 1.36 (t, J=7Hz, 3H)
, 1.55 (S, 3H), 2.03 (8, 3H), 4
．． 49CL J=7Hz, 2H), 5.90 (8, IH
), 6.90 (m, IH), 7.2-7.4°Cm.

5H), 7.50 (t, J-7Hz, IH), 7
．． 6-7.7 (m.

2H),? , 91 (8, IH), 7.97 (d, J
−? )iz, IH), 8.24 (d, J=7Hz
, IH), 8.47 (S, IH), but are not limited to these.

Next, examples of hydrazone compounds according to the present invention are given below. 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.
The upper layer of the carrier generation layer is provided with a carrier generation substance having high carrier generation efficiency, such as a dye or pigment as a main component,
A photoreceptor formed by using the present hydrazone compound dissolved or dispersed in a binder resin with addition of a chemical sensitizer or an electron-withdrawing compound as necessary as a carrier transport layer, and its carrier generation. There is a photoreceptor in which a layer and a carrier transport layer are laminated in reverse 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, vinegar/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.
Seeds or more can be heated and used.

The amount of these binder resins added to the photoconductive compound is 0.2 to 10 times the weight ratio, preferably 0.
．． In the range of 5 to 5 times, if the amount is less than this, the photoconductive compound will precipitate in the photosensitive layer or on the surface, resulting in poor adhesion to the support, and if it is more than this, the sensitivity will decrease.

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
PlDBP, 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 trifluoromethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, rhodamine B, and rhodamine 3B1. Zansen dyes such as Acridine Red B, acridine dyes such as Acridine Orange 2G, Acridine Orange 2G, Flaveosin, thiazine dyes such as Methylene Blue and Methylene Green, Cabri Blue, Melt Lab, etc. Other examples include oxazine dyes, cyanine dyes, steryl dyes, pyrylium salts, thiapyrylium salts, and squareium salt dyes.

In addition, metal-free 7 is a photoconductive pigment that generates carriers with extremely high efficiency through light absorption in the photosensitive layer.
Examples include 7-thalocyanine pigments such as talocyanine and phthalocyanine containing various metals or metallized compounds, perylene pigments such as perylene imide and herilenic anhydride, and 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 in the above-mentioned photosensitive material 1 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.

Ki is different from the sensitizers listed above (so-called spectral sensitizers).
It is also possible to add a sensitizer (so-called chemical sensitizer) for the purpose of improving K sensitivity.

Examples of the sensitizer include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4-chloro-
m-cresol, p-chlorobenzoylacetanilide, N,N'-diethylbarbylffi, 3-(β-
Examples include oxyethyl)-2-phe/l/imino-thiazolidone, malonic acid dianilide, 3°5,3',5'-tetrachloromalonic acid dianilide, α-su7tol, 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
, 4.7-trinitrofluorenone, 1-methyl-4-
Examples include nitrofluorenone, 2,7-sinitro-3,6-dimethylfluorenone, 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 additives 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.

Examples of 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 selon rub,
Solvents such as methyl selon lupus acetate alone or in combination
A mixed solvent of more than one species or a solvent such as alcohols, acetonitrile, N,N-dimethylformamide, mether ethyl lactone, etc. may be further added and used if necessary.

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. 5! Example 1: 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 thus obtained pigment dispersion 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 A1 was mixed with a polyarylate resin (U-polymer manufactured by Unitika) in a ratio of 1=1.
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 carrier transport layer with a dry film thickness of 20 μm.

The laminated electrophotographic photoreceptor thus prepared was evaluated for electrophotographic characteristics using an electrostatic recording tester (manufactured by Kawaguchi Electric, 5P-428) K.

Measurement conditions: applied voltage -6KV, static A3° As a result, the light half-reduction exposure amount for white light during charging is 2.3
It showed a very high sensitivity value of lux·sec.

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

When the change in charged potential was calculated by repeating 10' times, 1
Compared to the initial potential of 950 V in the 103rd test, the initial potential in the 103rd test was 930 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 light half-life exposure: flE"/2 (lux seconds) and the initial potential Vo (volts) were measured, and the values are shown in Table 1. Furthermore, charging and neutralization (static neutralization light: white light at 400 lux x
After repeating the same process 10' times with 1 second irradiation as one cycle, the initial potential Vo (volts) and the light half-exposure amount E
1/2 is shown in Table 1.

Examples 6-9 A bisazo A material having the following structure was used as a charge generating substance.

That is, 1 part by weight of pigment, 1 part by weight of polyester resin (Pylon 200 manufactured by Toyobo Co., Ltd.), and 1 part by weight of tetrahydrofuran.
The mixture was mixed with 1 part of 00i and dispersed with glass beads for 2 hours using a paint conditioner. 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 iv film thickness was approximately 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 Hf1l.
A photoreceptor was prepared. This photoreceptor was evaluated under the same measurement conditions as in Example 1. The results are shown in Table 2.

Table 2

Claims (1)

[Scope of Claims] 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, A is an aromatic ring or a heterocycle, R^1 is hydrogen, an alkyl group, or an aryl group, and R^2 has a substituent. An optional alkyl group, aralkyl group, or aryl group, R^
3. R^4 may be the same or different and represent hydrogen, an alkyl group that may have a substituent, an aralkyl group, or an aryl group. Further, R^3 and R^4 may form a ring. m represents 1 or 2, and n represents 0 or 1. )