JP3320480B2 - 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 photoreceptor comprising a charge generating layer and a charge transporting layer. More specifically, the present invention relates to a photoconductive squarium compound subjected to a specific treatment as a charge generating material. The present invention relates to an electrophotographic photoconductor contained therein.

[0002]

2. Description of the Related Art At present, as a photoreceptor for electrophotography, a function-separated type photoreceptor containing a charge generating substance having photosensitivity at the wavelength of a light source and a charge transporting substance having a high charge transfer speed is widely used. . In this case, azo pigments, perylene pigments, phthalocyanine pigments, squarium compounds, etc., are used as the charge generating substances, and hydrazone compounds, styryl compounds, pyrazoline compounds, triphenylamine compounds, etc., which are low-molecular conductive substances, are used as the charge transporting substances. It is used.

[0003]

Conventionally, when a squarium compound is used as the charge generating material in such a photoreceptor, the photosensitivity in the oscillation wavelength region of the semiconductor laser or LED is high, but the chargeability is low and the darkness is low. There were problems such as initial characteristics such as large attenuation, sensitivity shift due to repeated use, and deterioration of charging ability.

An object of the present invention is to provide a high-sensitivity electrophotographic photoreceptor containing a squarium compound as a charge generating substance and having excellent chargeability.

[0005]

The electrophotographic photoreceptor of the present invention has a charge generation layer and a charge transport layer, and comprises dissolving a photoconductive squarium compound in sulfuric acid to form a sulfuric acid solution. A squarium compound obtained by mixing a water-soluble organic solvent inert to sulfuric acid and a sulfuric acid solution, and hydrogenating the mixture in the mixed solution to contain a squarium compound in the charge generation layer.

The electrophotographic photoreceptor of the present invention has a charge generation layer and a charge transport layer, and comprises dissolving a photoconductive squarium compound in sulfuric acid to form a sulfuric acid solution.
The charge generation layer contains a squaraium compound obtained by mixing an aqueous solution of a water-soluble organic solvent inert to sulfuric acid and a sulfuric acid solution.

Further, the electrophotographic photoreceptor of the present invention has a charge generation layer and a charge transport layer, and dissolves a photoconductive squarium compound in sulfuric acid to form a sulfuric acid solution. The charge generation layer contains a squarium compound obtained by hydrogenation.

[0008]

According to the present invention, the squarium compound is dissolved in sulfuric acid to form a sulfuric acid solution.
One obtained by mixing a water-soluble organic solvent inert to sulfuric acid and a sulfuric acid solution and hydrogenating the mixture, and one obtained by mixing an aqueous solution of a water-soluble organic solvent inert to sulfuric acid and a sulfuric acid solution. Or those obtained by hydrogenating a sulfuric acid solution. By performing such a treatment, the squarium compound is atomized, refined, and used. The squarium compound subjected to such treatment is compared with the one before treatment,
The particle size is very fine, and the dispersibility is also improved. In the present invention, the squarium compound can be used as long as it has photoconductivity. One example is shown in Chemical formula 1.

[0009]

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(Wherein, X represents hydrogen, fluorine, a hydroxyl group, a methyl group, etc.)

As the water-soluble organic solvent inert to sulfuric acid,
Examples thereof include water-soluble lower alcohols, glycols, glycol ethers, carboxylic acids, and the like.

An embodiment of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the electrophotographic photoconductor of the present invention. This electrophotographic photoreceptor is obtained by forming a charge generation layer 2 containing a photoconductive squarium compound 4 as a charge generation substance on a conductive support 1, and stacking a charge transport layer 3 thereon. is there. The charge transport layer 3 is made of a binder resin in which the charge transport material 5 is dispersed. Note that a small amount of the charge transport material 5 may be added to the charge generation layer 2.

The electrophotographic photoreceptor shown in FIG. 2 has a structure in which a charge transport layer 3 is formed on a conductive support 1 and a charge generation layer 2 is laminated thereon.

In the electrophotographic photoreceptor of the present invention, the charge generation layer 2 is formed by depositing a squarium compound directly on the conductive support 1 or by applying a solution dispersed in a binder resin to the conductive support. 1 or on the charge transport layer 3. As the binder resin, in addition to thermoplastic resins such as polyester resin, polycarbonate resin and polyvinyl butyral resin, thermosetting resins such as polyurethane resin, epoxy resin, amino resin, melamine resin, formalin resin, phenol resin, and alkyd resin For example, a resin having high volume resistivity and high mechanical strength is used.

As the charge transporting material 5 and the binder resin used for the charge transporting layer 3, those used in a usual electrophotographic photoreceptor can be used. Charge transport material 5
For example, a conductive polymer or a low-molecular conductive material can be used. Representative examples of the conductive polymer include polyvinyl carbazole and the like, and examples of the low-molecular conductive substance include a hydrazone compound, a styryl compound, and a triphenylamine compound. The binder resin can be used as long as it has an excellent adhesive property and an insulating property.

The charge generating layer 2 or the charge transporting layer 3 has flexibility, adhesiveness, and the like as long as the sensitivity characteristics of the photosensitive member are not impaired.
A plasticizer may be used to improve the mechanical strength, or an antioxidant may be used to improve the chemical strength.
If necessary, an intermediate layer for improving the adhesion to the conductive support 1, preventing injection of electrons from the conductive support 1, and the like, or a surface protective layer for improving mechanical properties may be provided.

The application of the charge generation layer 2, the charge transport layer 3, the intermediate layer and the surface protective layer is usually carried out using a doctor blade, a wire bar, a roll coater or the like. In the case of the electrophotographic photoreceptor of the present invention, the thickness of the charge generation layer 2 is 5 μm or less,
The thickness is preferably 0.5 to 1 μm, and the thickness of the charge transport layer 3 is 5 to 50 μm, preferably 10 to 20 μm. Further, when an intermediate layer and a surface protective layer are provided, the thickness is 1 μm.
The following is preferred.

As the conductive support 1, those conventionally used can be used. Specifically, a metal support such as aluminum, stainless steel, copper, or brass, or a support obtained by depositing aluminum, indium oxide, or the like on an insulating support may be used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

(Example 1) Squaric acid and N, N-
Dimethylaniline was heated in a mixed solvent of n-butanol and toluene and dehydrated by an azeotropic reaction to synthesize a photoconductive squarium compound shown in Chemical formula 2. After purification by solvent extraction, 1 g of a squarium compound was added to 10 g of sulfuric acid, and the obtained sulfuric acid solution was dropped into diethylene glycol dimethyl ether under an ice bath. Thereafter, a squarium compound was prepared by slowly adding 100 g of water.

[0021]

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Example 2 2 g of the squarium compound prepared in Example 1 and a polymer solution obtained by dissolving 18 g of a polyester resin in 180 g of cyclohexanone were mixed.
The mixture was dispersed with a shaking disperser for 3 hours. The obtained solution is Al
Apply with a wire bar on the evaporated polyester film,
A charge generation layer having a thickness of 0.5 μm after drying and a squarium compound concentration of 10 wt% was formed.

Next, a hydrazone compound represented by Chemical Formula 3 as a charge transport material was added to a polymer solution obtained by dissolving 12 g of a polycarbonate resin in 108 g of cyclohexanone.
0 g was dissolved. The obtained solution was applied on the charge generation layer with a wire bar to form a charge transport layer having a thickness of 17 μm, thereby producing an electrophotographic photoreceptor.

[0024]

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The electrophotographic photoreceptor thus produced was corona-charged at -6 KV in a dark place, and then exposed to a W lamp having an illuminance of 2.5 μW / cm ² for 20 seconds to examine the photoreceptor characteristics. . The photoreceptor characteristics include an initial charging potential V ₀ after charging, a time t D required for the surface potential to darkly decay from −620 V to −600 V, and −300 V to −300 V.
The amount of exposure E1 / 2 required for light attenuation and the residual potential Vr after light irradiation for 20 seconds were measured. Further, the same operation was repeated on the electrophotographic photosensitive member, and V ₀ (10
00), tD (1000), E1 / 2 (1000), Vr
(1000) was measured and the durability was examined. The results were as follows.

V ₀ = −732 V tD = 12 seconds E 1/2 = 0.46 μJ / cm ² Vr = −47 V V ₀ (1000) = − 728 V tD (1000) = 10 seconds E1 / 2 (1000) = 0. 42 μJ / cm ² Vr (1000) = − 50 V

Example 3 An electrophotographic photoreceptor was manufactured under the same conditions as in Example 2 except that the compound represented by Chemical Formula 4 was used as the charge transporting substance. The photoreceptor characteristics were as follows.

[0028]

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V ₀ = −741 V tD = 13 seconds E1 / 2 = 0.45 μJ / cm ² Vr = −43 V V ₀ (1000) = − 738 V tD (1000) = 11 seconds E1 / 2 (1000) = 0. 44 μJ / cm ² Vr (1000) = − 47 V

Example 4 An electrophotographic photoreceptor was manufactured under the same conditions as in Example 2 except that the concentration of the squarium compound in the charge generation layer was 5 wt%. The photoreceptor characteristics were as follows.

V ₀ = −791 V tD = 16 sec E1 / 2 = 0.83 μJ / cm ² Vr = −49 V V ₀ (1000) = − 789 V tD (1000) = 15 sec E1 / 2 (1000) = 0. 80 μJ / cm ² Vr (1000) = − 52 V

Comparative Example 1 Example 2 was repeated except that the synthesis and purification by solvent extraction were performed in Example 1, and the squarium compound represented by Chemical Formula 2 was used as the charge generating material without the treatment after dissolving in sulfuric acid. Under the same conditions as in the above, an electrophotographic photoconductor was prepared. The photoreceptor characteristics were as follows.

V ₀ = −727 V tD = 10 sec E 1/2 = 0.73 μJ / cm ² Vr = −51 V V ₀ (1000) = − 715 V tD (1000) = 8 sec E1 / 2 (1000) = 0. 68 μJ / cm ² Vr (1000) = − 56 V

Comparative Example 2 An electrophotographic photoreceptor was produced using the squarium compound used in Comparative Example 1 under the same conditions as in Example 4. The photoreceptor characteristics were as follows.

V ₀ = −773 V tD = 12 seconds E 1/2 = 1.28 μJ / cm ² Vr = −59 V V ₀ (1000) = − 761 V tD (1000) = 10 seconds E1 / 2 (1000) = 1. 06 μJ / cm ² Vr (1000) = − 64 V

Example 5 Squaric acid and N, N-
Dimethylaniline was heated in a mixed solvent of n-butanol and toluene and dehydrated by an azeotropic reaction to synthesize a photoconductive squarium compound shown in Chemical formula 2. After purification by solvent extraction, 1 g of a squarium compound was added to 10 g of sulfuric acid, and the resulting sulfuric acid solution was added dropwise to an aqueous solution of diethylene glycol dimethyl ether to prepare a squarium compound. An electrophotographic photoreceptor was produced under the same conditions as in Example 2 except that the squarium compound thus obtained was used. Photoconductor characteristics were the same as in Example 2.

Example 6 Squaric acid and N, N-
Dimethylaniline was heated in a mixed solvent of n-butanol and toluene and dehydrated by an azeotropic reaction to synthesize a photoconductive squarium compound shown in Chemical formula 2. After purification by solvent extraction, 1 g of a squarium compound was added to 10 g of sulfuric acid, and the resulting sulfuric acid solution was dropped into water to prepare a squarium compound. An electrophotographic photoreceptor was produced under the same conditions as in Example 2 except that the squarium compound thus obtained was used. Photoconductor characteristics were the same as in Example 2.

[0038]

According to the present invention, the photoconductive squarium compound subjected to a specific treatment has a very fine particle size,
Excellent dispersibility. The squarium compound thus obtained has high photosensitivity, is chemically stable, has high durability, and is an excellent charge generating substance. Therefore, the electrophotographic photoreceptor of the present invention is a highly sensitive photoreceptor having excellent charging ability. Furthermore, since it has a wide absorption range from the visible region to the infrared region, it can be applied to laser printers, liquid crystal shutter printers, LED printers, copiers, electrophotographic plate making systems, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electrophotographic photoreceptor of the present invention.

FIG. 2 is a cross-sectional view of the electrophotographic photoreceptor of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 charge generation layer 3 charge transport layer 4 photoconductive squarium compound 5 charge transport material

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-204850 (JP, A) JP-A-3-269062 (JP, A) JP-A-1-2999884 (JP, A) Recent photoconductive materials and the development and practical application technology Book of the photoreceptor, Japan, Japan Science and information Co., Ltd. publications Department, July 31, 1986, 86, 87 (58) investigated the field (Int.Cl. ^7, DB name ) G03G 5/06 384

Claims (3)

(57) [Claims] 1. A photoreceptor for electrophotography having a charge generating layer and a charge transport layer, after the photoconductive squarylium compound was sulfuric acid solution was dissolved in sulfuric acid, glycol er
A photoreceptor for electrophotography, comprising a charge generation layer containing a squaraium compound obtained by mixing a terium with the sulfuric acid solution and adding water to the mixture. 2. In an electrophotographic photoreceptor having a charge generation layer and a charge transport layer, a photoconductive squarium compound is dissolved in sulfuric acid to form a sulfuric acid solution, and then glycol glycol
A photoreceptor for electrophotography, wherein the charge generation layer contains a squarium compound obtained by mixing an aqueous solution of ter and the sulfuric acid solution. 3. The method according to claim 2, wherein the glycol ether is diethylene.
請 characterized by glycol dimethyl ether der Rukoto
3. The electrophotographic photoconductor according to claim 1 or claim 2 .