JP3130154B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member containing a novel stilbene compound.

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2. Description of the Related Art 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. . 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 selenium photoreceptors have thermal stability, deterioration of characteristics due to crystallization, difficulty in production, and cadmium sulfide have moisture resistance and durability. Organic materials have better film-forming properties, better flexibility, and lighter Because of its advantages such as good transparency and easy design of a photoreceptor for a wide range of wavelengths by an appropriate sensitization method, its practical use is gradually receiving attention.

Incidentally, the photoreceptor used in the electrophotographic technology is generally required to have the following 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.

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However, much research has been done on photoconductive polymers such as polyvinyl carbazole as organic photoconductive materials to date. It is difficult to say that the adhesiveness is not sufficient and that the above-mentioned basic properties as a photoreceptor are sufficiently provided.

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

In order to improve such a point, an organic photoreceptor having higher sensitivity characteristics has been developed in which a carrier generating function and a carrier transporting function are shared by different substances. 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, and a photoreceptor having an arbitrary performance can be easily manufactured. Has been advanced.

As described above, various improvements have been made in the production of electrophotographic photoreceptors, but the basic properties required for the above-described photoreceptors and the requirements for high durability are satisfied. What to do has not yet been obtained.

An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and high durability. In particular, it is an object of the present invention to provide a photoreceptor which has a high charging characteristic, has almost no decrease in sensitivity even when used repeatedly, and has a stable charging potential.

[0010]

The present inventors have studied a photoconductive substance having high sensitivity and high durability.
The present inventors have found that a novel stilbene compound represented by the formula (1) is effective, and have reached the present invention.

In the chemical formula 1, Ar represents an optionally substituted aryl group, and R ₁ and R ₂ represent an optionally substituted alkyl group, an aralkyl group, an aryl group, and a heterocyclic group. R ₃ represents a hydrogen atom or a lower alkyl group;
R ₄ , R ₅ , and R _{6 each} represent a hydrogen atom or an optionally substituted alkyl group, aryl group, or heterocyclic group;
₇ , R ₈ and R ₉ represent a hydrogen atom, a halogen atom, or a lower alkyl group.

Here, specific examples of Ar include aryl groups such as phenyl group, methoxyphenyl group, tolyl group, chlorophenyl group, and naphthyl group. Specific examples of R ₁ and R ₂ include methyl group, Butyl group, alkyl group such as 3-methyloctyl group, benzyl group, 4-methylbenzyl group, aralkyl group such as 2-chlorophenethyl group, phenyl group, tolyl group, chlorophenyl group, aryl group such as naphthyl group, or A heterocyclic group such as a pyridyl group or an indolyl group, and specific examples of R ₃ include a hydrogen atom,
Alternatively, a lower alkyl group such as a methyl group, an ethyl group, or a propyl group, and specific examples of R ₄ , R ₅ , and R ₆ include a hydrogen atom, a methyl group, a butyl group, and a 2-methylhexyl group. Alkyl group such as phenyl group, methoxyphenyl group, tolyl group, chlorophenyl group, aryl group such as naphthyl group, or heterocyclic group such as pyridyl group, indolyl group, or R ₇ , R ₈ , and R ₉ Specific examples include a hydrogen atom, a halogen atom such as fluorine, chlorine, and bromine, and a lower alkyl group such as a methyl group and an ethyl group.

The compounds represented by Chemical Formula 1 can be produced by the methods of the following synthesis examples. Synthesis Example (Synthesis of Exemplified Compound 3)

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The aldehyde compound of the formula (10.0 g) and 4
-To a DMF solution (250 ml) of styrylbenzyltriphenylphosphonium bromide (14.2 g)
After adding potassium t-butoxide (4.47 g) and stirring at room temperature overnight (about 14 hours), the reaction solution was poured into 1000 ml of ice water, and the precipitated crystals were collected by filtration. This was washed with water, dried, and purified by column chromatography to obtain 8.2 g of a crystal of Exemplified Compound 8.

Melting point: 154.0 to 156.0 ° C., yield: 60
%. NMR (δ, ppm, CDCl ₃ ) 7.2-7.6 (m, 16H), 6.8-7.2 (m,
16H), 6.71 (d, 1H)

Next, the stilbene compounds according to the present invention will be exemplified, but the present invention is not limited thereto.

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

Various methods are known for using these stilbene compounds as electrophotographic photosensitive members.
For example, a photoconductor in which a stilbene compound and a sensitizing dye are dissolved or dispersed in a binder resin by adding a chemical sensitizer or an electron-withdrawing compound as necessary, and provided on a conductive support. Or, in the form of a laminated structure comprising a carrier generation layer and a carrier transport layer, on the conductive support,
On a carrier generation layer provided mainly with a carrier generation substance having a high carrier generation efficiency, such as a dye or a pigment,
A photoreceptor formed by laminating the stilbene compound as a carrier transport layer by dissolving or dispersing the stilbene compound in a binder resin by adding a chemical sensitizer or an electron withdrawing compound as necessary, and a carrier generation layer thereof There is a photoreceptor in which a carrier and a carrier transport layer are reversely laminated on a conductive support, and the present invention can be applied to any case.

As a support for producing a photoreceptor using the compound of the present invention, a metal drum, a metal plate, a paper subjected to electroconductive 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 acetate
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 and the like. Among them, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polyarylate resin, phenol resin and the like are excellent in the potential characteristics as a photoconductor.

These resins can be used alone or in combination of two or more kinds as a copolymer. The amount added to the photoconductive compound of these binder resins is
The ratio is 0.2 to 10 times by weight, preferably 0.1 to 10 times.
When the amount is less than 5 to 5 times, the photoconductive compound precipitates in the photosensitive layer or on the surface, and the adhesion to the support is deteriorated. When the amount is more, the sensitivity is lowered.

Next, some of the film-forming binder resins to be used are rigid and have low mechanical strength such as tension, bending, compression and the like. In order to improve these properties, when a substance giving plasticity is added. Is also required. These materials include phthalic acid esters (eg, DOP, DBP,
DIDP, etc.), phosphate esters (eg, TCP, TO
P, etc.), sebacic esters, adipic esters,
Examples include nitrile rubber and chlorinated hydrocarbons. In the case of adding such a substance that imparts plasticity, the addition of more than necessary deteriorates the potential characteristics. Therefore, the ratio is preferably 20% or less by weight with respect 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 and Victoria blue, erythrosine, rhodamine B and rhodamine 3B. , Aziridine dyes such as acridine orange 2G, acridine orange R, and flaveosin, thiazine dyes such as methylene blue and methylene green, capri blue, and meldra blue. Oxazine dyes, other cyanine dyes, styryl dyes, pyrylium salts, thiapyrylium salts, and squarium salt dyes.

In the photosensitive layer, photoconductive pigments which generate carriers with extremely high efficiency by light absorption include perylene-based pigments such as peryleneimide and perylene anhydride, other quinacridone pigments, anthraquinone-based pigments, and azo-based pigments. There are pigments and the like.

Among these pigments, those using bisazo pigments and trisazo pigments as those having particularly high carrier generation efficiency give high sensitivity and provide excellent electrophotosensitive materials. 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 chemical sensitizer include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4-chloro-m-cresol, p-chlorobenzoylacetanilide, N, N'-diethylbarbituric acid , 3- (β-oxyethyl) -2-phenyliminothiazolidone, malonic acid dianilide, 3,5,3 ′,
5'-tetrachloromalonic acid dianilide, α-naphtho-
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 stilbene compound of the present invention and further increasing the sensitizing effect. Examples of the electron-withdrawing substance include 1-chloroanthraquinone, 1-nitroanthraquinone, 2,3-dichloronaphthoquinone, 3,3-dinitrobenzophenone, 4-nitrobenzalmalone nitrile, phthalic anhydride, and 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 stilbene compound of the present invention is dissolved or dispersed in an appropriate solvent together with the above-mentioned various additives depending on the form of the photoreceptor, and the coating solution is coated on the above-mentioned conductive support. And dried to produce a photoreceptor.

Examples of the coating solvent include halogenated hydrocarbons such as chloroform, dichloroethane, trichloroethane and trichloroethylene, aromatic hydrocarbons such as benzene, toluene and xylene, dioxane, tetrahydrofuran, methyl cellosolve, dimethyl cellosolve, methyl cellosolve acetate and the like. Can be used alone or as a mixture of two or more solvents or, if necessary, a solvent such as alcohols, acetonitrile, N, N-dimethylformamide, methyl ethyl ketone or the like.

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EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Embodiment 1

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1 part by weight of Chemical Formula 37 and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and dispersed together with glass beads for 2 hours using a paint conditioner. The pigment dispersion thus obtained was applied to an aluminum-evaporated polyester film using an applicator and dried to a film thickness of about 0.2.
A film of the carrier generating substance of μ was formed.

Next, the stilbene compound represented by Exemplified Compound 3 is mixed with a polyarylate resin (U-Polymer manufactured by Unitika) at a weight ratio of 1: 1 to prepare a 10% solution using dichloroethane as a solvent. This solution was applied on the generated material film using an applicator to form a carrier transport layer having a dry film thickness of 20 μm.

The laminated electrophotographic photoreceptor thus manufactured was evaluated for electrophotographic characteristics using an electrostatic recording tester (SP-428 manufactured by Kawaguchi Electric). Measurement conditions: applied voltage -6
KV, static No. 3 (rotation speed mode of the turntable with the sample attached). As a result, the light half-life exposure amount with respect to white light at the time of charging showed an extremely high sensitivity value of 1.1 lux · sec.

Further, repeated use was evaluated using the same apparatus. Repeated by the place of obtaining the change in the charge potential at 10 ³ times with respect to the first initial potential -710V, 10
^{The third} charging potential was -700 V, and it was found that the reduction in potential due to repetition was small and stable, indicating excellent characteristics.

Examples 2 to 5 A laminated photoreceptor was prepared in the same manner as in Example 1 except that the stilbene compounds shown in Table 1 were used instead of the stilbene compounds used in Example 1, and the same procedures as in Example 1 were carried out. Under the measurement conditions, the light half-life exposure amount E1 / 2 (looks / 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 the 10 ³ times the same repeated as one cycle,
Table 1 shows the initial potential Vo (volt) and the light half-life exposure amount E1 / 2.
It was shown to.

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[Table 1] *: (Looks and seconds)

Examples 6 to 13

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The compound of the formula (38) was used as a charge generating substance. That is, 1 part by weight of Chemical Formula 38 and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and dispersed together with glass beads for 2 hours using a paint conditioner. 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 0.2 μ.

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Next, a carrier transport layer was formed in the same manner as in Example 1 by using the exemplified compounds shown in Table 2 and the comparative compounds of Chemical Formulas 39 and 40, respectively, to produce a laminated photoreceptor. This photoreceptor was evaluated under the same measurement conditions as in Example 1. The results are shown in Table 2.

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[Table 2] *: (Looks and seconds)

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As is apparent from the above, according to the present invention, an electrophotographic photosensitive member having high sensitivity and high durability can be provided.

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a stilbene compound represented by the following formula 1. Embedded image (In the formula 1, Ar represents an aryl group which may have a substituent, and R ₁ and R ₂ each represent an alkyl group, an aralkyl group, an aryl group or a heterocyclic group which may have a substituent. , R
₃ represents a hydrogen atom or a lower alkyl group, and R ₄ , R ₅ ,
And R ₆ represent a hydrogen atom or an optionally substituted alkyl group, an aryl group, or a heterocyclic group, and R ₇ , R ₈ , and R ₉ represent a hydrogen atom, a halogen atom, or a lower alkyl group . )