JP3009948B2 - 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 fluorenylidene 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. That the dissipation (light attenuation) of the
(4) The residual charge after light irradiation is small.

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However, many studies have been made on photoconductive polymers such as polyvinyl carbazole as organic photoconductive substances 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. Has been advanced.

As described above, various improvements have been made in the preparation of an electrophotographic photoreceptor. However, the electrophotographic photoreceptor satisfies the basic characteristics required for the photoreceptor and the requirements for high durability. 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.
And found that the novel fluorenylidene compound is effective.

In the formula 1, Ar ₁ and Ar ₂ each represent an aryl group which may have a substituent, and R _{1 and} R _{2 each} represent a halogen atom, an alkyl group which may have a substituent, or an aralkyl group. And an alkoxy group. n and m are each 0
Represents an integer of 4.

Preferred examples of the substituent for Ar ₁ and Ar ₂ include a halogen atom, an alkyl group, an alkoxy group, and a substituted amino group. Here, specific examples of Ar ₁ and Ar ₂ include substituted or unsubstituted aryl groups such as a phenyl group, a methoxyphenyl group, a tolyl group, a chlorophenyl group, a dimethylaminophenyl group, a naphthyl group, and a methylnaphthyl group. Can be. Specific examples of R ₁ and R ₂ include a halogen atom such as fluorine, chlorine, and bromine; an alkyl group such as a methyl group, an ethyl group, and a propyl group;
Benzyl, methylbenzyl, chlorobenzyl, β
Aralkyl groups such as -phenylethyl group and α-naphthylmethyl group; and alkoxy groups such as methoxy group, ethoxy group and isobutyloxy group. Further, m and n each represent an integer of 0 to 4. When n or m is 2 or more, each substituent may be the same or different.

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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A benzene solution (110 m) of the aldehyde compound of formula 2 (4.13 g) and diphenylamine (3.6 g) is used.
l), p-toluenesulfonic acid monohydrate (0.1
g) was added and refluxed for 2 hours. The solvent is distilled off under reduced pressure, and the resulting oil is left to precipitate crystals. The crystals were collected by filtration and washed with a small amount of benzene-hexane to obtain 4.17 g of crystals of Exemplified Compound 3.

Melting point: 144.0 to 145.0 ° C., yield: 55
%. NMR (δ, ppm, CDCl ₃ ) 6.54 (d, 1H), 6.65 (t, 1H), 7.0
−7.1 (m, 3H), 7.2-7.4 (m, 10
H), 7.44 (s, 1H), 7.6-7.8 (m, 3
H)

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

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The electrophotographic photoreceptor according to the present invention comprises one or more fluorenylidene compounds as described above.
It is obtained by containing more than one kind and has excellent performance.

Various methods are known for using these fluorenylidene compounds as electrophotographic photoreceptors. For example, a photoconductor in which a fluorenylidene 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. Alternatively, in the form of a laminated structure composed of a carrier generation layer and a carrier transport layer, the present invention is applied to a carrier generation layer provided mainly with a carrier generation substance having a high carrier generation efficiency, such as a dye or a pigment, on a conductive support. A photoreceptor formed by laminating a fluorenylidene compound as a carrier transport layer by dissolving or dispersing 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 obtained by laminating a carrier transport layer on a conductive support in reverse, and the present 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 may be 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 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,
Phosphoric acid ester (eg, TCP, TOP)
And the like, sebacic esters, adipic esters, nitrile rubbers, chlorinated hydrocarbons and the like. 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.

Examples of photoconductive pigments that generate carriers with extremely high efficiency by light absorption in the photosensitive layer include metal-free phthalocyanines, phthalocyanine pigments such as phthalocyanines containing various metals or metalized compounds, perylene imides, and the like. There are perylene pigments such as perylene anhydride, other quinacridone pigments, anthraquinone pigments, and azo pigments.

Among these pigments, those using bisazo pigments, trisazo pigments, and phthalocyanine pigments having particularly high carrier generation efficiency provide high sensitivity and an excellent electrophotosensitive material. Further, the dye added to the 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, as the inorganic photoconductive substance, selenium, selentellurium alloy, cadmium sulfide,
Examples include 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-phenylimino-thiazolidone, malonic acid dianilide, 3,5,3 ′,
5'-tetrachloromalonic acid dianilide, α-naphthol, p-nitrobenzoic acid and the like.

A certain electron withdrawing compound can be added as a sensitizer for forming a charge transfer complex with the fluorenylidene 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-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 fluorenylidene 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, a fluorenylidene compound represented by Exemplified Compound No. 3 was converted to a polyarylate resin (U-product of Unitika).
Polymer) in a 1: 1 weight ratio to prepare a 10% solution using dichloroethane as a solvent. This solution is applied on the carrier-generating substance film by an applicator to form a carrier transport layer having a dry film thickness of 20 μm. Formed.

The laminated electrophotographic photoreceptor thus prepared 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. As a result, the light half-life exposure amount with respect to white light during charging was 2.2 lux · sec, which was a very high sensitivity value.

Further, repeated use was evaluated using the same apparatus. When the change in the charged potential due to repetition of 10 ³ times was obtained, the initial potential of −985 V for the first time was 10 ^3.
The initial potential at the time of the measurement was -965 V, and it was found that the potential was not reduced by repetition and was stable, indicating excellent characteristics.

Examples 2 to 5 A laminated photoreceptor was prepared in the same manner as in Example 1 except that the fluorenylidene compounds shown in Table 1 were used instead of the fluorenylidene compounds used in Example 1. Under the measurement conditions, the light half-life exposure amount E1 / 2 (lux · second) and the initial potential Vo (volt) were measured, and the values are shown in Table 1. Further charging - neutralization: the initial potential Vo (volts) and the light half-decay exposure E1 / 2 after was subjected to the same repeated 10 ^three times as one cycle (discharging light 400 lux × 1 sec illumination with white light) Table 1 It was shown to.

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[Table 1]

Examples 6 to 12 Titanium oxyphthalocyanine was used as a charge generating substance. That is, 1 part by weight of titanium oxyphthalocyanine 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 generation layer. The thickness of this thin film was about 0.2 μ.

Next, a carrier transporting layer was formed in the same manner as in Example 1 using each of the exemplified compounds shown in Table 2 and the comparative compounds represented by Chemical Formulas 38 and 39, to thereby 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]

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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.

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Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member comprising a fluorenylidene compound represented by the following formula 1. Embedded image (In the formula ₁ , Ar ₁ and Ar ₂ each represent an aryl group which may have a substituent, and R ₁ and R _{2 each} represent a halogen atom, an alkyl group which may have a substituent, an aralkyl group, Represents an alkoxy group, n and m each represent an integer of 0 to 4)