JP2690541B2 - Electrophotographic photoreceptor - Google Patents

Description

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 for electrophotographic photoreceptors, and have been extensively studied and put to practical use. Have been. In recent years, organic photoconductive materials have been actively studied for these inorganic materials, and some of them have been put to practical use as photoconductors for electrophotography.

Generally speaking, inorganic materials such as thermal stability in selenium photoreceptors, deterioration of characteristics due to crystallization, difficulty in production, etc., and in the case of cadmium sulfide, moisture resistance,
In contrast to the situation where it is not always possible to be satisfied due to durability, industrial waste treatment problems, etc.
Organic materials have good film-forming properties and excellent flexibility,
Since it has advantages such as light weight, good transparency, and easy design of a photoreceptor in a wide range of wavelengths by an appropriate sensitization method, its practical use has been attracting attention.

By the way, the photoreceptor used in electrophotographic technology is
In general, the following are required as basic properties. That is, (1) high chargeability against corona discharge in a dark place, (2) little leakage (dark decay) of the obtained charge in a dark place, and (3) charge charge 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 polyvinyl carbazole as organic photoconductive materials, but these have not always had sufficient film properties, flexibility, and adhesiveness. It is difficult to say that the photoconductor has sufficient basic properties as a photoconductor.

On the other hand, for the organic low-molecular-weight photoconductive compound, by selecting a binder and the like used for forming the photoreceptor, a photoreceptor having excellent mechanical strength such as film properties, adhesion, and flexibility can be obtained. Although possible, it is difficult to find a suitable compound that can retain high sensitivity properties.

In order to improve such a point, development of an organic photoconductor having higher sensitivity characteristics by sharing a carrier generating function and a carrier transporting function with different substances has been carried out. The feature of such a photoreceptor, which is called a function-separated type, is that a material suitable for each function can be selected from a wide range. Has been advanced.

(C) Object of the Invention As described above, various improvements have been made in the preparation of an electrophotographic photoreceptor. However, the basic properties required for the photoreceptor and the high durability and the like are required. The one that satisfies the demand has not yet been sufficiently obtained.

An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and high durability. In particular, the photoreceptor of the present invention
An object of the present invention is to provide a photoreceptor which has high charging characteristics, hardly causes a decrease in sensitivity even when used repeatedly, and has a stable charging potential.

(D) Constitution of the Invention As a result of research on a photoconductive substance having high sensitivity and high durability, the present inventors have found that a novel hydrazone compound represented by the following general formula [I] is effective. The present invention has been found.

(In the formula, R ¹ is an alkyl group which may have a substituent,
An aralkyl group, an aryl group, R ² is hydrogen, an alkyl group,
Alkoxy group, R ³ is hydrogen, an alkyl group, an aryl group, R ⁴ and R ⁵ may be the same or different and may have a substituent, an alkyl group, an aralkyl group or an aryl group. R ⁶ and R ^{7, which} may be the same or different, each represent hydrogen, an alkyl group which may have a substituent, an aralkyl group or an aryl group. However, the case where R ⁶ and R ⁷ simultaneously become a methyl group is excluded. Further, R ⁶ and R ⁷ may form a ring. n represents 0 or 1. Here, specific examples of the substituent R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, a benzyl group, a β-phenylethyl group, a p-methylbenzyl group,
Examples thereof include aralkyl groups such as p-methoxybenzyl group and α-naphthylmethyl group, phenyl groups, naphthyl groups, tolyl groups, xylyl groups, chlorophenyl groups, methoxyphenyl groups, and methylnaphthyl groups.
Specific examples of the substituent R ² 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 of the substituent R ³ Examples thereof 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 group, a tolyl group, a methoxyphenyl group and a chlorophenyl group, and specific examples of the substituents R ⁴ and R ⁵ Examples include alkyl groups such as methyl group, ethyl group, propyl group and butyl group, benzyl group, β-phenylethyl group, chlorobenzyl group, methylbenzyl group, methoxybenzyl group, aralkyl group such as α-naphthylmethyl group. Aryl groups such as phenyl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group, tolyl group, xylyl group and chlorophenyl group. It can be given to the group.

Specific examples of R ⁶ and R ⁷ include hydrogen atom, alkyl groups such as ethyl group and propyl group, benzyl group, aralkyl groups such as p-methylbenzyl group, phenyl group, p-
An aryl group such as a methoxyphenyl group 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 (Exemplified Compound No. 3) 1.45 g of hydrazone compound represented by the formula [II], 1.23 g of 3,3-bis (p-methoxyphenyl) acetaldehyde,
And p-toluenesulfonic acid monohydrate (30 mg) in toluene (30)
Heat to reflux with ml for 30 hours. The product was purified by silica gel chromatography (benzene: hexane = 1: 1) to give compound No.
1.2 g of 3 was obtained. Melting point 197-199 [deg.] C.

'HNMR (δ, ppm, CDCl ₃ ) 3.64 (S, 3H) 3.77 (S, 3H) 6.5-7.5 (m, 29H) Next, the hydrazone compound according to the present invention will be exemplified, but the invention is not limited thereto.

The electrophotographic photoreceptor according to the present invention is obtained by containing one or more hydrazone compounds as described above, and has excellent performance.

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

For example, a photoreceptor comprising a conductive support on which a hydrazone compound and a sensitizing dye are optionally added with a chemical sensitizer or an electron-withdrawing compound and dissolved or dispersed in a binder resin. Alternatively, in the form of a laminated structure consisting of a carrier generating layer and a carrier transporting layer, on a conductive support, on a carrier generating layer mainly provided with a carrier generating substance having a high carrier generating efficiency, for example, a dye or a pigment, A photoreceptor comprising a hydrazone compound, if necessary, added with a chemical sensitizer or an electron-withdrawing compound and dissolved or dispersed in a binder resin, as a carrier transport layer, or a carrier generation layer and a carrier thereof There are photoconductors and the like in which a transport layer and a conductive support are laminated in reverse order, but the invention can be applied to any case.

As a support for preparing a photoreceptor using the compound of the present invention, a metal drum, a metal plate, a paper subjected to conductive processing, a plastic film or a belt-like support is used.

As the film-forming binder resin used for forming a photosensitive layer on such a support, various resins can be mentioned depending on the application field. For example, for 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 And phenoxy resins. Among these, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polyarylate resin, phenol resin and the like are excellent in potential characteristics as a photoreceptor.

These resins can be used alone or as a mixture of one or more of them as a copolymer.

The amount of the binder resin to be added to the photoconductive compound is 0.2 to 10 times by weight, preferably 0.5 to 10 times.
If the amount is less than 5 times, the photoconductive compound precipitates in the photosensitive layer or on the surface, and the adhesion to the support is deteriorated. If the amount is more than 5 times, the sensitivity is lowered.

Next, some of the film-forming binder resins used are rigid and weak in mechanical strength such as tension, bending, and compression, and it is also necessary to add a substance that imparts plasticity to improve these properties. Become.

These materials include phthalic acid esters (eg, DO
P, DBP, DIDP, etc.) phosphoric acid ester (for example, TCP, TOP, etc.), sebacic acid ester, adipic acid ester, nitrile rubber, chlorinated hydrocarbon and the like. In the case of adding such a substance that imparts plasticity, if added in excess, the potential characteristics will be deteriorated. Therefore, the ratio is preferably 20% or less by weight relative to the binder resin.

Next, sensitizing dyes added to the photosensitive layer include triphenylmethane dyes represented by methyl violet, crystal violet, ethyl violet, night blue, Victoria blue, etc., erythrosine, rhodamine B, rhodamine 3B, acridine red. B, etc., acridine dyes represented by acridine orange 2G, acridine orange R, flaveosin, etc., thiazine dyes represented by methylene blue, methylene green, oxazine dyes represented by capri blue, Meldora blue, etc. And cyanine dyes, styryl dyes, pyrylium salts, thiapyrylium salts, and squarium salt dyes.

Further, in the photosensitive layer, as a photoconductive pigment that generates a carrier with extremely high efficiency by light absorption, metal-free phthalocyanine, phthalocyanine-based pigments such as phthalocyanine containing various metals or metalized compounds, perylene imide, perylene anhydride Pigments, quinacridone pigments, anthraquinone pigments, azo pigments and the like.

Among these pigments, bisazo pigments, trisazo pigments, and phthalocyanine-based pigments having particularly high carrier generation efficiency give high sensitivity and an excellent electrophotosensitive material.

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

In addition to the above-mentioned sensitizers (so-called spectral sensitizers), sensitizers (so-called chemical sensitizers) for the purpose of further improving the sensitivity can be added.

Examples of the sensitizer include p-chlorophenol and m-
Chlorophenol, p-nitrophenol, 4-chloro-m-cresol, p-chlorobenzoylacetanilide, N, N'-diethylbarbituric acid, 3- (β-oxyethyl) 2-phenyliminothiazolidone, malonic acid Examples include dianilide, 3,5,3 ′, 5′-tetrachloromalonic acid dianilide, α-naphthol and p-nitrobenzoic acid.

Further, a certain kind of electron-withdrawing compound can be added as a sensitizer for forming a charge transfer complex with the hydrazone compound of the present invention and further increasing the sensitizing effect.

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

In addition, an antioxidant, an anti-curl agent and the like can be added as necessary to the photoreceptor.

The hydrazone compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives described above depending on the form of the photoreceptor, and the coating solution is applied on the conductive support described above, and dried. To produce a photoreceptor.

As a coating solvent, chloroform, dichloroethane,
Halogenated hydrocarbons such as trichloroethane and trichlorethylene, aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, and solvents such as dioxane, tetrahydrofuran, methyl cellosolve, dimethyl cellosolve and methyl cellosolve acetate, alone or in combination of two or more. A mixed solvent or, if necessary, a solvent such as alcohols, acetonitrile, N, N-dimethylformamide, methyl ethyl ketone and the like can be further added and used.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these.

Example 1 1 part by weight of the pigment shown in 1) and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and the mixture was dispersed together with glass beads for 2 hours by a paint conditioner device. The pigment dispersion thus obtained was applied on an aluminum-evaporated polyester film using an applicator and dried to form a carrier-generating substance film having a thickness of about 0.2 μm.

Next, the hydrazone compound represented by Exemplified Compound No. 4,
Polyarylate resin (Unitika U-polymer) and 1: 1
Were mixed at a weight ratio of 10% to prepare a 10% solution using dichloroethane as a solvent, and this solution was applied onto the film of the above-mentioned carrier generating substance by an applicator to form a carrier transport layer having a dry film thickness of 20 μm.

The laminated electrophotographic photoreceptor thus produced was evaluated for electrophotographic characteristics using an electrostatic recording tester (SP-428 manufactured by Kawaguchi Electric).

Measurement conditions: Printing voltage-6KV, static No.3.

As a result, the amount of light half-exposure to white light during charging is
It showed a very high sensitivity value of 2.2 lux · sec.

Further, repeated use was evaluated using the same apparatus. When the change in charge potential due to repetition of 10 ³ times was determined,
The initial potential of the ^third time is 950 against the initial potential of 980V.
V, indicating that the potential was not reduced by repetition and was stable, showing excellent characteristics.

Examples 2 to 5 Example 1 was repeated except that the hydrazone compounds shown in Table 1 were used instead of the hydrazone compounds used in Example 1.
A laminated photoreceptor was prepared in the same manner as in Example 1, and under the same measurement conditions as in Example 1, the light half-life exposure amount E1 / 2 (lux · second) and the initial potential Vo
(Volts) were measured, and the values are shown in Table 1. Further charge-discharge (discharge light: 400 lux x 1 second irradiation with white light)
After 10 ^three similar repeated as one cycle, showing initial potential Vo (volts) and the light half decay exposure E1 / 2 in Table 1.

Examples 6 to 9 Bisazo pigments having the following structure as charge generating substances Was used. That is, 1 part by weight of this pigment and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and the mixture was dispersed with glass beads for 2 hours by a paint conditioner device. The pigment dispersion thus obtained was applied on the same support as in Example 1 using an applicator to form a carrier generating layer. The thickness of this thin film was about 0.2μ.

Next, using the exemplified compounds No. 3, No. 4, No. 13, and No. 14, a carrier transport layer was formed in the same manner as in Example 1 to prepare a laminated photoreceptor. This photoreceptor was evaluated under the same measurement conditions as in Example 1. The results are shown in Table 2.

Continuation of the front page (56) Reference JP-A-60-198550 (JP, A) JP-A-60-119564 (JP, A) JP-A-60-191264 (JP, A) JP-A-61-177461 (JP , A) JP 62-264059 (JP, A)

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing a hydrazone compound represented by the following general formula [I] on a conductive support. (In the formula, R ¹ is an alkyl group which may have a substituent, an aralkyl group and an aryl group, R ² is a hydrogen atom, an alkyl group and an alkoxy group, R ³ is a hydrogen atom, an alkyl group and an aryl group,
R ⁴ and R ⁵ may be the same or different, and an alkyl group which may have a substituent, an aralkyl group and an aryl group, and R ⁶ and R ⁷ may be the same or different. Also represents hydrogen, an alkyl group which may have a substituent, an aralkyl group or an aryl group. However, the case where R ⁶ and R ⁷ simultaneously become a methyl group is excluded. Further, R ⁶ and R ⁷ may form a ring. n represents 0 or 1. )