JPH0789229B2 - Photoconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photoreceptor containing a novel disazo pigment in a photocharge generating layer.

2. Description of the Related Art A photoconductor in which an organic charge generating substance is compounded in a resin binder and applied on a conductive substrate is widely used for practical purposes due to its low toxicity, ease of manufacture, low cost, etc. ing.

Proposed typical organic charge generating materials include phthalocyanine, TNT, PVK, and perylene derivatives, which are used in combination with appropriate charge transport materials such as hydrazones and oxadiazoles.

Further, in recent years, a technique of using various disazo pigments in a charge generation layer has been proposed. For example, in JP-A-55-69147, (A in the formula is (R ₂ is H or Cl) or And n is a number of 1 or 2) In JP-A-57-96345, There is disclosed a technique of using as a charge generating material.

Problems to be Solved by the Invention However, conventionally, during the manufacturing process, the dispersion stability of the pigment dispersion, particularly for the charge generation layer coating, is poor, and it is a big problem that the properties of the pot life coating are adversely affected. there were.

The present invention solves the above problems and provides a novel disazo pigment as a charge generating material for an organic photoconductor, which is excellent in dispersion stability of a coating liquid, and is also excellent in photosensitivity, red reproducibility, and repeatability. With the goal.

Means for Solving the Problems The present invention has the general formula [I]: (In the formula, A represents an aromatic carbocycle or an aromatic heterocycle which may have a substituent, Ar represents a fluorine atom as a substituent,
Chlorine, phenylene optionally having bromine, biphenylene, oxybiphenylene, or Relates to a photoreceptor containing a disazo pigment represented by

The disazo pigment used in the present invention has the general formula [I]: (In the formula, A represents an aromatic carbocycle or an aromatic heterocycle which may have a substituent, Ar represents a fluorine atom as a substituent,
Chlorine, phenylene optionally having bromine, biphenylene, oxybiphenylene, or Is represented).

In the general formula [I], A is an aromatic carbocycle or an aromatic heterocycle which may have a substituent, for example, Etc., a substituent for Ar, for example, fluorine, chlorine, may have a halogen atom such as bromine, phenylene, biphenylene, oxybiphenylene, or, Represents

Compound [I] can be synthesized, for example, by the following two methods.

[Synthesis Method 1] Azo compound of 3-hydroxynaphthalic anhydride [II]: (Where A is as defined above) and 1 mol of diamine [III]: NH ₂ —Ar—NH ₂ [III] (wherein Ar is as defined above).

[Synthesis Method 2] 3-hydroxynaphthalic acid diimide compound [IV]: (In the formula, Ar the same meaning as defined) 1 mol of diazonium compound of _{[VI]: A-N 2} + · BF 4 - [VI] cup (wherein, A is the same as defined) with two moles of Ring reaction.

The diimide compound [IV] can be obtained by dehydration condensation of 3-hydroxy-naphthalic anhydride and diamine compound [III].

Diazonium compound [VI] is the corresponding nitro compound [VI]
I]: A-NO ₂ [VII] (wherein A is as defined above) is reduced by a conventional method, for example, tin and hydrochloric acid to give an amine compound [VIII]: A-NH ₂ [VIII] (formula In the above, A has the same meaning as described above), and by reacting it with sodium nitrite in a hydrochloric acid solution, a diazonium salt [VI] can be obtained.

The coupling agent used in the present invention is not limited, and a commercially available coupling agent may be appropriately used. Examples of coupling agents include, for example, substituted or unsubstituted phenol, naphthol, or polycyclic or heterocyclic compounds having these groups.

Even when the photoconductor of the present invention is a dispersion type containing the disazo pigment represented by the general formula [I] in the photoconductive layer, it comprises a charge generation layer and a charge transport layer laminated, and the charge generation layer has the general formula [I]. It may be a function-separated type in which the disazo pigment represented by the formula I] is pigmented.

In the case of the dispersion type photoreceptor, the photoreceptor of the present invention is prepared by dissolving or dispersing the disazo pigment represented by the general formula [I] in a suitable solvent together with the binder resin, and adding a charge transporting substance if necessary. It can be produced by coating the resulting coating liquid on a conductive substrate and drying it to form a photoconductive layer having a thickness of usually 5 to 30 μm, preferably 6 to 20 μm.

The disazo pigment of the present invention is used for the binder resin of the photoconductive layer.
0.5 to 50% by weight, and more preferably 0.5 to 5% by weight. If less than 0.5% by weight, sufficient sensitivity cannot be obtained,
If it is more than 5% by weight, problems such as poor charging property and poor film forming property occur.

Examples of the charge transport material include hydrazone compounds,
Examples include pyrazoline compounds, triphenylamine compounds, oxadiazole compounds, triphenylmethane compounds, polyester compounds of anthracene derivatives, and the amount of these charge transport substances is 280% by weight with respect to the binder resin of the photoconductive layer. % Or less, preferably 25 to 75% by weight. In the present invention, particularly preferable charge transporting substances are N-ethylcarbazole-3-aldehyde methylphenylhydrazone (MPH), diethylaminobenzaldehyde diphenylhydrazone (DEH) and the like.

The binder resin includes, but is not limited to, saturated polyester resin, polyamide resin, acrylic resin, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer. Polymer, polycarbonate, vinyl chloride-
Thermoplastic binder such as vinyl acetate copolymer, cellulose ester, polyimide; thermosetting binder such as epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin, xylene resin, alkyd resin, thermosetting acrylic resin Adhesive: photocurable resin; photoconductive resin such as poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene.

It is desirable that these resins have a volume resistance of 1 × 10 ¹⁴ Ω · cm or more when measured alone.

In the case of the function-separated type, the photoreceptor of the present invention is coated with a coating solution prepared by dispersing the disazo pigment of the present invention in a solution in which a binder resin is dissolved on a conductive substrate and dried to form a charge generation layer. A charge transporting material and a binder resin are dissolved on a suitable solvent to form a charge transporting layer, which is then dried to form a charge transporting layer. At this time, the thickness of the charge generation layer is 0.01 ~
The amount of the disazo pigment is 0.5 to 50% by weight, preferably 0.5 to 5% by weight, based on the binder resin of the charge generation layer. The thickness of the charge transport layer is 2 to 100 μm, preferably 10 to 20 μm, and the amount of the charge transport material is 10 to 80 relative to the binder resin of the charge transport layer.
%, Especially 25-75% by weight. As the charge transport material and the binder resin, the same materials as in the dispersion type are used, and in the function-separated type photoreceptor, the charge generation layer may be on the surface side and the charge transport material may be on the substrate side. The reverse is also possible.

Pigment Synthesis Example Synthesis of Disazo Pigment (a) of the Present Invention Synthesis of fluoroborate diazonium salt of 9-fluorenone (C): 2.31 g of 2-amino-9-fluorenone hydrochloride (d) obtained by reducing ₂ -nitro-9-fluorenone (e) with SnCl ₂ and hydrochloric acid. Disperse (0.01 mol) in 100 ml of hydrochloric acid,
This dispersion was cooled to 0 to 5 ° C. with stirring, and an aqueous solution prepared by dissolving 1 g of sodium nitrite in 20 ml of water was added dropwise thereto. After the dropping, continue stirring under cooling for an additional 1 hour,
After that, unreacted materials were filtered off, borohydrofluoric acid (42%) was added to the obtained filtrate, and the produced crystals were collected by filtration to obtain fluoroborate (c) of diazonium salt.

4,4'-bis- (3-hydroxy-naphthalic anhydride)
-Synthesis of para-phenylenediimide compound (b) 3-hydroxy-naphthalic anhydride (f) (manufactured by Tokyo Kasei Kogyo) 5 g (0.023 mol) and para-phenylenediamine (f) 5 g (0.046 mol) were dissolved in 300 ml of glacial acetic acid. Then, the reaction was carried out at the boiling point of acetic acid for 2 hours.

After the reaction, the mixture was cooled to room temperature, the precipitated crystals were collected by filtration, and washed well with methanol. The obtained crystals were grayish green and did not melt below 300 ° C.

From elemental analysis and infrared absorption spectrum measurement, it was found that this crystal was a naphthalimide compound shown below. The yield was 6 g, and the elemental analysis values were as follows.

Gray-green crystal Decomposition point: 300 ° C or higher Elemental analysis value: Infrared absorption spectrum (KBr tablet method) νco (second amide) 1700 cm ^-1 Synthesis of disazo pigment of the present invention: 4,4'-bis- (3-hydroxy-naphthalic anhydride) -paraphenylenediimide synthesized above (B) 2.5g (0.
005 mol) and 2.98 g of the diazonium salt (c) synthesized above
(0.01 mol) to N, N-dimethylformamide (DMF) 400m
A solution prepared by dissolving 5 g of sodium acetate in 100 ml of water was added dropwise thereto at 0 to 5 ° C. in about 30 minutes. After the dropping is completed,
After stirring at room temperature for 3 hours, the precipitated crystals were collected by filtration. The obtained crude crystal cake was dispersed in DMF1 and stirred at room temperature for 3 hours, and then the crystals were collected by filtration again, and this operation was repeated twice. After that, the crystals were washed with water and dried to obtain 3.5 g (76.9%) of disazo pigment (a) was obtained.

Red-purple crystal: Decomposition point: 300 ° C or higher Elemental analysis value: Infrared absorption spectrum (KBr tablet method): νco (second amide) 1690 cm ¹ The disazo compound of the present invention is effective as a charge generating material for a layered type photoreceptor, and in order to clarify that point, a specific example is given below. An example is shown.

Examples 1 to 10 0.45 parts by weight of the disazo compound of the present invention (hereinafter abbreviated as "part") and 0.45 part of a polyester resin "Vyloret 200" (manufactured by Toyobo Co., Ltd.) were dispersed together with 50 parts of cyclohexanone by a sand grinder. The resulting dispersion of the disazo compound was applied onto a 100 μm thick aluminized mylar by a film applicator so that the dry film thickness would be 0.3 g / m ^2, and then dried. On the charge generation layer thus obtained, 70 parts of N-ethylcarbazole-3-aldehydemethylphenylhydrazone (MPH) and 70 parts of a polycarbonate resin "K-1300" (manufactured by Teijin Chemicals) were added to 1,4-dioxane 400.
The solution dissolved in each part was applied so that the dry film thickness was 16 μm to form a charge transport layer. In this way, an electrophotographic photosensitive layer photoreceptor having a photosensitive layer composed of two layers was obtained.

Table 1 shows the values of the half exposure (E1 / 2) as the sensitivity of these photoconductors. The half-exposure is that the photoconductor is first charged in the dark by a corona discharge of -6.5 KV, then the illuminance is 5 Lux.
The amount of exposure required for the surface potential to be attenuated to half of the initial surface potential was obtained by exposure with the white light.

Examples 11 to 20 Electrophotographic photoreceptors were obtained in the same manner as in Examples 1 to 10 except that diethylaminobenzaldehyde diphenylhydrazone (DEH) was used as the charge transfer amount. Table 2 shows the values of the half exposure (E1 / 2) as the sensitivity of these photoconductors.

Effect of the Invention The present invention provides a novel disazo pigment for photocharge generation.

The disazo pigment of the present invention improves the dispersion stability of the photocharge generation layer coating liquid.

The photoreceptor obtained according to the present invention has improved photosensitivity, repeated stability and color sensitivity.

Claims (1)

[Claims] 1. A general formula [I]: (In the formula, A represents an aromatic carbocycle or an aromatic heterocycle which may have a substituent, Ar represents a fluorine atom as a substituent,
Chlorine, phenylene optionally having bromine, biphenylene, oxybiphenylene, or The photoconductor which contains a disazo pigment represented by