JP3286868B2 - 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, and more particularly, to an electrophotographic photosensitive member having high sensitivity in a wide wavelength range from a visible light region to a near infrared light region.

[0002]

2. Description of the Related Art Hitherto, it has been known that certain azo compounds are effective as charge generating pigments for electrophotographic photoreceptors. In general, an electrophotographic photosensitive member is obtained by efficiently injecting a charge generating layer (hereinafter abbreviated as CGL) containing a charge generating pigment capable of generating charge carriers by light onto a conductive support and efficiently charging the charge carriers. A so-called function-separated type photoconductor in which a charge transport layer (hereinafter abbreviated as CTL) containing a charge transport material having a transporting ability, and a charge generation material and a charge transport material are contained in a single layer. There is a single layer type photoreceptor. Conventional azo compounds used in this type of photoreceptor include, for example, JP-A-47-37543.
And a bisazo compound having a benzine skeleton described in JP-A-52-55643 or a bisazo compound having a stilbene skeleton described in JP-A-52-8832. JP-A-53-132347 describes a trisazo pigment having sensitivity up to the near infrared region.

[0003]

However, the photoreceptor for electrophotography using the conventional azo compound is generally low in sensitivity, so that it is not suitable as a photoreceptor for a high-speed copying machine or a laser printer using a semiconductor laser as a writing light source. It was not enough.

Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity in a wide wavelength range.

[0005]

According to the present invention, in an electrophotographic photoreceptor having a photoconductive layer formed on a conductive support, at least one of the photoconductive layers is provided with: An electrophotographic photoreceptor characterized by containing at least one asymmetric trisazo pigment represented by the general formula (1) is provided.

Embedded image [In the above formula, Ar ₁ means a residue represented by the following formula (A) and Ar ₂ means a residue represented by the following formula (B)]

Embedded image

Embedded image (Wherein, R represents an alkyl group)

Further, according to the present invention, there is provided an electrophotographic photoreceptor in which the layer containing at least one of the asymmetric trisazo pigments represented by the above general formula 1 is a charge generating layer.

[0007] The electrophotographic photoreceptor of the present invention has a constitution in which the photoconductive layer, particularly the charge generation layer, contains the asymmetric trisazo pigment represented by the above general formula (1). It has high sensitivity in a wide wavelength range from light to near-infrared light.

As a photoreceptor for electrophotography, a charge generation layer containing a charge generation substance that generates charge carriers by absorbing light on a conductive support, and the charge carriers are easily injected and transported. A so-called laminated photoreceptor (or a function-separated type photoreceptor) provided with a photoconductive layer comprising a charge transporting layer containing a charge transporting substance having an ability, and a charge generating substance and a charge transporting substance on a conductive support There is a single-layer type photoreceptor (or a dispersion type photoreceptor) provided with a photoconductive layer composed of a single layer in which a is dispersed in a binder resin, but the photoreceptor of the present invention may be any of the above. .

The novel asymmetric trisazo pigment represented by the general formula 1 used in the present invention functions as a charge generating substance in the photoreceptor. In the present invention, it is important to use this specific asymmetric trisazo pigment, and other elements of the electrophotographic photoreceptor, such as a conductive support, a charge transport material, and a binder resin, are not particularly limited. .

The trisazo pigment used in the present invention comprises tris (diazonium salt) represented by the following general formula (2):
Two or three kinds of couplers selected from the couplers described below are coupled in two or three steps sequentially, or represented by the general formula 3 or 4 obtained by the coupling reaction in each step. After isolation of the diazonium salt compound to be obtained, the compound can be further obtained by coupling with a corresponding coupler.

Embedded image (Where X represents an anionic functional group)

Embedded image (In the formula, X represents an anionic functional group, and Ar ¹ is the same as defined in the general formula 1.)

Embedded image (Wherein X represents an anionic functional group, and Ar ¹ and Ar ² are the same as defined in the general formula 1)

At present, a charge generation pigment used for an electrophotographic photoreceptor is required to have a high charge generation performance particularly for near infrared light. Although the asymmetric trisazo pigment used in the present invention has a high charge generation ability, various characteristics can be exhibited particularly by the combination of the coupler residues in the general formula (1). That is, an asymmetric pigment containing a coupler residue having a benzocarbazole group has sensitivity up to near-infrared light in a longer wavelength range, and is effective for an electrophotographic photoconductor for a semiconductor laser. Further, an asymmetric pigment containing two or more coupler residues having two or more halogen groups,
Higher sensitivity.

The asymmetric trisazo pigment used in the present invention is produced by a coupling reaction between tris (diazonium salt) and two or more couplers as described above.
Therefore, it is necessary to strictly control the ratio of the amount of tris (diazonium salt) and the charged amount of each coupler at the time of the reaction, based on the chemical structure of the desired asymmetric trisazo pigment. On the other hand, tris (diazonium salt) is generally easily decomposed and is unstable in a solution state dissolved in a solvent. Therefore, when a solution of tris (diazonium salt) previously dissolved in a solvent is used when producing an asymmetric trisazo pigment, the ratio of the amount of tris (diazonium salt) to the amount of each coupler during the coupling reaction is a desired ratio. On the contrary, it is a factor that lowers the purity and yield of the finished asymmetric trisazo pigment.

Therefore, in the step of producing the asymmetric trisazo pigment, the coupler and tris (diazonium salt) are charged into a reaction vessel in a solid state in order to obtain a higher purity reaction product in a high yield. It is preferable to adopt a method in which a reaction is carried out by dissolving a solvent in a solvent, or by introducing tris (diazonium salt) in a solid state into a coupler solution composed of a coupler and a solvent to cause a reaction. Preferably, tris (diazonium salt) is charged in a solid state into a coupler solution consisting of

Specific examples of the coupler used in the above reaction, that is, specific examples of Ar ¹ -H, Ar ² -H and Ar ³ -H are shown in Tables 1 to 11, and the azo pigment used in the present invention is shown in Tables 1 to 11. Can be used as long as it is a coupler for an azo pigment used in a conventionally known electrophotographic photoreceptor, and the coupler is not limited thereto.

[0015]

[Table 1- (1)]

[0016]

[Table 1- (2)]

[0017]

[Table 2- (1)]

[0018]

[Table 2- (2)]

[0019]

[Table 3- (1)]

[0020]

[Table 3- (2)]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

[Table 8]

[0026]

[Table 9- (1)]

[0027]

[Table 9- (2)]

[0028]

[Table 9- (3)]

[0029]

[Table 10- (1)]

[0030]

[Table 10- (2)]

[0031]

[Table 10- (3)]

[0032]

[Table 11- (1)]

[0033]

[Table 11- (2)]

As described above, the photoconductive layer (photosensitive layer) of the electrophotographic photoreceptor of the present invention can be of a dispersion type or a function separation type by combining a charge generating substance and a charge transporting substance. In the case of a dispersion type layer structure, a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder is provided on a conductive support (substrate). In the case of the function separation type, a charge generation material or a charge generation layer containing a charge generation material and a binder is formed on a substrate, and a charge transport layer containing a charge transport material and a binder is formed thereon. In the case of a positive charge type, the charge generation layer and the charge transport layer may be stacked in reverse order. In the case of the function separation type, a charge transport material may be contained in the charge generation layer. In particular, in the case of the positive charging configuration, the sensitivity becomes good.

Further, an intermediate layer may be provided between the photosensitive layer and the substrate in order to improve the adhesive property and the charge blocking property. Further, in order to improve mechanical durability such as abrasion resistance, a protective layer may be provided on the photosensitive layer. As the binder used for forming the charge generation layer, the charge transport layer and the dispersion type photosensitive layer, any binder can be used as long as it is a conventionally known binder for an electrophotographic photosensitive member having good insulating properties, and is particularly limited. Not something. Specific examples include polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin, polyethylene, polyvinyl chloride, polyvinyl acetate, polystyrene,
Examples include phenol resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicon resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyarylate, polyacrylamide, polyamide, and phenoxy resin. These binders can be used alone or as a mixture of two or more.

The intermediate layer provided as needed includes:
Generally, a resin is a main component. However, considering that a photosensitive layer is coated thereon with a solvent, these resins are preferably resins having high solvent resistance to general organic solvents. Such resins include polyvinyl alcohol,
Water-soluble resins such as casein and sodium polyacrylate,
Curable resins that form a three-dimensional network structure, such as alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethanes, melamine resins, phenol resins, and epoxy resins. The intermediate layer may include, for example, titanium oxide,
Fine powder pigments of metal oxides such as silica, alumina, zirconium oxide, tin oxide and indium oxide can be added.

As the solvent or dispersion medium used for forming the charge generation layer and the charge transport layer, N, N '
-Dimethylformamide, acetone, methyl ethyl ketone, xylene, chloroform, 1,2-dichloroethane, dichloromethane, monochlorobenzene, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide and the like. As a method for forming the photosensitive layer, a method of dipping the substrate in a coating solution for the charge generation layer and the charge transport layer, a method of spraying the coating solution on the substrate, and the like are used.

The conductive support (substrate) used in the electrophotographic photoreceptor of the present invention includes metal drums and sheets of aluminum, brass, stainless steel, nickel, etc., and materials such as polyethylene phthalate, polypropylene, nylon, and paper. Sheet or cylindrical substrate such as plastic, paper, etc., which is made by depositing metal such as aluminum or nickel or applying conductive material such as titanium oxide, tin oxide, indium oxide, carbon black etc. with appropriate binder Is mentioned.

As the charge transporting material in the present invention, any conventionally known charge transporting material can be used, and it is not limited to a specific material. Examples of such a charge transport material include triphenylamine-based, hydrazone-based, and stilbene-based materials. To explain this in more detail,
JP-B-32372, benzidine compounds, biphenylylamine-based compounds such as JP-A-2-178669, triarylamine-based compounds such as JP-A-3-285960, JP-A-64-566, etc. Ethylene compounds, JP-A-64-25748 and JP-A-56-
No. 29245, distyrylbenzene compounds, Japanese Patent Application No. 3-99496, etc., styrylpyrene compounds, JP-A-52-139066, JP-A-52-139065, and other oxadiazole-based compounds; 55-15
4955, JP-A-55-156954, JP-A-55-156954
Hydrazone-based compounds such as JP-A-52063 and JP-A-56-81850, arylidenefluorene compounds disclosed in JP-A-52-128373, and JP-A-58-1984.
No. 25, stilbene compounds such as JP-A-57-73075, JP-A-55-88064, JP-A-49-1.
Pyrazoline compounds such as Japanese Patent Publication No.
-555, JP-B-51-10983, and JP-A-55-10883.
No. 108667, polyarylalkane compounds,
Styryl anthracene compounds such as JP-A-51-94829 and JP-A-51-98260;
58552, styrylcarbazole compounds and the like.

[0040]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Production Example 1 0.57 g (1.5 mmol) of 2-hydroxy-3- (2-ethylphenyl) carbamoyl-11H-benzo [a] carbazole (coupler No. 51) was added to DMF1
Then, 0.88 g (1.5 mmol) of 4,4 ′, 4 ″ -tris (diazonium tetrafluoroborate) triphenylamine was added at room temperature. After stirring at room temperature for 10 minutes, 2- Hydroxy-3- (2-
Methyl-4-chlorophenyl) carbamoyl-8-chloro-11H-benzo [a] carbazole (coupler N
O. 184) 1.306 g (3.0 mmol) in DMF
A solution dissolved in 100 ml was added, and then 8 ml of a 9% aqueous sodium acetate solution was added, followed by stirring at room temperature for 2 hours. The generated precipitate is separated by filtration, heated to 80 ° C., and DMF 200 ml
And then washed twice with 200 ml. It was dried at 120 ° C. under reduced pressure to obtain a trisazo compound (hereinafter referred to as P-1) represented by Formula 5 below. The yield was 58%. FIG. 1 shows the infrared absorption spectrum (KBr tablet method) of P-1 and Table 12 shows the elemental analysis values.

[0042]

Embedded image

[0043]

[Table 12]

Production Example 2 2-hydroxy-3- (2-methyl-4-chlorophenyl) carbamoyl-8-chloro-11H-benzo [a]
0.653 g of carbazole (coupler No. 184)
(1.5 mmol) was dissolved in 100 ml of DMF, and 0.88 g (1.5%) of 4,4 ′, 4 ″ -tris (diazonium tetrafluoroborate) triphenylamine was dissolved at room temperature.
Mmol). After stirring at room temperature for 10 minutes,
1.14 g (3.0 mmol) of 2-hydroxy-3- (2-ethylphenyl) carbamoyl-11H-benzo [a] carbazole (coupler NO.51) was added to DMF1
A solution dissolved in 00 ml was added, and then 8 ml of a 9% aqueous sodium acetate solution was added, followed by stirring at room temperature for 2 hours. The precipitate formed was filtered off, heated to 80 ° C. and washed three times with 200 ml of DMF and then twice with 200 ml. The resultant was dried at 120 ° C. under reduced pressure to obtain a trisazo compound represented by the following formula 6 (hereinafter referred to as P-2). The yield was 60%. Infrared absorption spectrum of P-2 (KBr tablet method)
Is shown in FIG. 2, and the elemental analysis values are shown in Table 13.

[0045]

Embedded image

[0046]

[Table 13]

Example 1 0.2 g of the trisazo compound P-1 obtained in Production Example 1 50 g of 4.0 g of a 2% solution of polyvinyl butyral (XYHL manufactured by UCC) in cyclohexanone was placed in 100 g of a 5 mmφ PSZ ball.
After performing ball milling for 5 days, 14 g of cyclohexanone was added, and ball milling was further performed for 1 day to prepare a CGL coating solution. The above-mentioned CGL coating solution was applied on a 75 μm polyester film on which aluminum was vapor-deposited by a doctor blade.
The resultant was dried by heating at 3 ° C. for 3 minutes to form CGL having a thickness of 0.3 μm.

Next, a CTL coating solution having the following composition was prepared,
After performing blade coating on the CGL,
Heat and dry at 130 ° C for 5 minutes,
A CTL film of about 20 μm was formed to form a photoreceptor. Polycarbonate resin (C-1400 manufactured by Teijin Chemicals Limited) 10 g α-phenylstilbene compound represented by the following formula 7 8 g Toluene 72 g

[0049]

Embedded image

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the trisazo compound was changed to the trisazo compound P-2 obtained in Production Example 2.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that a trisazo pigment represented by the following formula 8 was used instead of the trisazo compound used in Example 1.

[0052]

Embedded image

Comparative example3  Instead of the trisazo compound used in Example 1, the following formula
Except for using the trisazo pigment shown in Chemical formula 9,
A photoconductor was prepared in the same manner as in Example 1.

[0054]

Embedded image

(Evaluation) The photosensitive members prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were charged at −5.5 Kv for 2 seconds at −5.5 Kv by an electrostatic property measuring device EPA8100 manufactured by Kawaguchi Electric Co., Ltd. ₂ and 800 volts on the photoreceptor
3. After charging, light from a 2856K tungsten lamp
The white sensitivity was measured by irradiating 5 lux. In addition, 78
Irradiation was performed through a 0 nm (half-width, 20 nm) bandpass filter, and the light sensitivity to 780 nm light was measured. Table 14 shows the results. In the table, E _1/10 (lux · se
c), E ′ _1/10 (μJ / cm ² ) are white sensitivity, 7
The light sensitivity is 80 nm, and each represents the necessary light amount at which the surface potential attenuates from 800 V to 80 V.

[0056]

[Table 14]

Table 14 shows that the photoreceptor of the present invention using the asymmetric trisazo pigment has high sensitivity to white light and near-infrared light.

[0058]

According to the electrophotographic photoreceptor of the present invention, the photoconductive layer contains the asymmetric trisazo pigment represented by the general formula (1). It has high sensitivity over a wide wavelength range up to the optical range.

In the electrophotographic photoreceptor of the present invention, since the asymmetric trisazo pigment is contained in the charge generation layer, the effect of improving the charge generation efficiency is added.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum (KBr tablet method) of the asymmetric trisazo pigment used in the present invention obtained in Production Example 1.

FIG. 2 is an infrared absorption spectrum (KBr tablet method) of the asymmetric trisazo pigment used in the present invention obtained in Production Example 2.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-108342 (JP, A) JP-A-2-247659 (JP, A) JP-A-1-292353 (JP, A) JP-A 64-64 JP-A-63-282744 (JP, A) JP-A-63-180959 (JP, A) JP-A-63-244048 (JP, A) JP-A-63-259573 (JP, A) JP-A-5-40354 (JP, A) JP-A-6-348049 (JP, A) JP-A-2-259655 (JP, A) JP-A-62-147463 (JP, A) JP-A-6-49433 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00 CA (STN)

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a photoconductive layer formed on a conductive support, wherein at least one of the photoconductive layers is provided with an asymmetrical structure represented by the following general formula (1): An electrophotographic photoreceptor comprising at least one trisazo pigment. Embedded image [In the above formula, Ar ₁ means a residue represented by the following formula (A), and Ar ₂ means a residue represented by the following formula (B)] Embedded image (Wherein, R represents an alkyl group) 2. The electrophotographic photoconductor according to claim 1, wherein the layer containing at least one asymmetric trisazo pigment is a charge generation layer.