JP2654198B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoconductor for electrophotography. More specifically, the present invention relates to an electrophotographic photoreceptor characterized in that a photosensitive layer on a conductive support contains a novel stilbene compound as a charge transporting substance.

[Conventional technology]

Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photosensitive members. However, photoreceptors using these photosensitive materials have not sufficiently satisfied the required performance as an electrophotographic photoreceptor, such as sensitivity, light stability, moisture resistance, and durability. For example, a photoreceptor using a selenium-based material has excellent sensitivity, but is easily crystallized due to heat or adhesion of dirt, and the characteristics of the photoreceptor are easily deteriorated. In addition, it has many drawbacks such as high cost because it is manufactured by vacuum evaporation, and difficulty in processing it into a belt shape due to lack of flexibility. A photoreceptor using a cadmium sulfide-based material has a problem in moisture resistance and durability, and a photoreceptor using zinc oxide has a problem in durability.

Various photoconductors using an organic photosensitive material have been studied in order to overcome the disadvantages of the photoconductor using an inorganic photosensitive material.

In recent years, among photoconductors developed to improve the above-mentioned disadvantages, a function-separated type photoconductor in which a charge generation function and a charge transport function are shared by different substances has been receiving attention. In this function-separated type photoreceptor, since a substance having each function can be selected from a wide range and combined, a photoreceptor with high sensitivity and high durability can be manufactured. is there.

The electrophotographic characteristics required of the charge transport material include (1) sufficient ability to accept the charge generated by the charge transport material, (2) rapid transport of the received charge, and (3) even in a low electric field. There is such a thing that the charge is sufficiently transported and no charge is left.

Furthermore, the photoreceptor is required to be stable against light, heat, and the like received during repeated charging, exposure, development, and transfer processes during imaging, and to have durability to obtain a reproducible image faithful to the original image. You.

Various compounds have been proposed as charge transport materials. For example, poly-N-vinyl carbazole has long been known as a photoconductive substance, and a substance using this as a charge transporting substance has been put to practical use. However, the poly-N-vinyl carbazole itself is poor in flexibility, fragile, and causes cracks. The durability was inferior to repeated use because it was easy. Further, when the flexibility is improved in combination with the binder, there is a disadvantage that the electrophotographic properties are inferior.

On the other hand, a low-molecular compound generally does not have a film property, and is usually mixed with a binder with an arbitrary composition to form a photosensitive layer. Many charge transport materials have been proposed as low molecular compounds. For example, a hydrazone compound has high sensitivity as a charge transporting substance,
-46761, JP-A-55-52064, JP-A-57-58156,
It is described in JP-A-57-58157 and the like. However, these have a problem of decomposition by ozone generated during corona charging, or stability against light and heat.Although the initial performance is excellent, the charge retention ability is reduced by repeated use, or the residual potential is accumulated. Due to the cause, the image was reduced in contrast or fogged.

Many other charge transport materials have been proposed, but none of them practically satisfies the required performance of electrophotographic photoconductors, and the development of even better photoconductors has been desired. .

[Problems to be solved by the invention]

An object of the present invention is to provide an electrophotographic photoreceptor having sufficient sensitivity and good durability, and another object is to provide a novel charge generating substance used for the photoreceptor.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the general formula (I) (Wherein, Ar ¹ and Ar ² are unsubstituted or substituted arylene groups, Ar ³ , Ar ⁴ , Ar ⁵ , and Ar ⁶ are unsubstituted or substituted aryl groups, and R ¹ and R ² are unsubstituted or substituted. A substituted alkyl group, an aralkyl group or an aryl group, R ¹ and R ² may be bonded to each other, and X is an oxygen atom, a sulfur atom or R ³ and R ⁴ are a hydrogen atom, an alkyl group, or an aryl group, and R ³ and R ⁴ may be bonded to each other. n represents an integer of 1 or 2. However, Is bonded to Ar ^{3 to} Ar ⁶ . The present inventors have found that the novel stilbene compound represented by the formula (1) gives an electrophotographic photoreceptor having excellent characteristics such as high sensitivity and high durability.

That is, the present invention is an electrophotographic photoreceptor characterized in that the photosensitive layer on the conductive support contains the stilbene compound represented by the general formula (I).

In Ar ¹ and Ar ² of the general formula (I), examples of the arylene group include: Examples of the substituent of the substituted arylene group include a halogen atom such as —Cl and —Br, an alkyl group such as a methyl group and an ethyl group, and an alkoxy group such as a methoxy group and an ethoxy group.

In Ar ³ , Ar ⁴ , Ar ⁵ and Ar ⁶ , examples of the aryl group include a phenyl group and a naphthyl group, and examples of the substituent include a halogen atom such as —Cl and —Br, a methyl group, and an ethyl group. And alkoxy groups such as propyl group and butyl group, and alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group.

Examples of the alkyl group in R ¹ and R ² include a methyl group, an ethyl group, a linear or branched propyl group, a pentyl group, a hexyl group, and an octyl group.Examples of the aralkyl group include a benzyl group and a phenethyl group. Group, cinnamyl group, nahethylmethyl and the like, and the aryl group can be a phenyl group and a naphthyl group. Groups, halogen atoms such as chlorine atom and bromine atom, and dialkylamino groups such as dimethylamino group and diethylamino group.

Further, as a group in which R ¹ and R ² are linked, And the like.

In R ³ and R ⁴ , examples of the alkyl group and the aryl group include those exemplified for R ¹ and R ² . R ³ and R ⁴ may combine with each other to form a cycloalkane ring such as cyclohexane and cyclooctane.

The compounds that can be used in the present invention are more specifically shown in Tables 1 to 14, but the compounds that can be used in the present invention are not limited to these.

The stilbene compound represented by the general formula (I) can be synthesized, for example, as follows.

General formula (II) (Wherein, Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , Ar ⁵ , Ar ⁶ X and n are Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , Ar ⁵ , Ar ⁶ , X ⁶ ) in the general formula (I). And an aldehyde compound represented by the general formula (III) (Wherein, R ¹ and R ² are the same as R ^1, R ² of general formula (I), R ⁵ represents an aryl group such as an alkyl group, a phenyl group such as a methyl group, an ethyl group) Table with The compound to be prepared is placed in a suitable solvent (for example, N, N-dimethylformamide, N, N-
Dimethylacetamide, 1,3-dimethyl-2-imidazolidinone).

The stilbene compound of the present invention, as a charge transport material,
The electrophotographic photoreceptor is used in combination with a charge generating substance.

As the charge-generating substance, any substance can be used as long as it has a charge-generating ability. ,
Examples thereof include organic dyes and pigments of anthraquinone type, cyanine type, azo type and the like. In particular, azo compounds can be suitably used.

Since the stilbene compound of the present invention does not have a film-forming ability by itself, it forms a photosensitive layer in combination with a binder. As the binder, an insulating polymer is used, and examples thereof include polystyrene, polyacrylamide, polyvinyl chloride, polyester resin, polycarbonate resin, epoxy resin, phenoxy resin, and polyamide resin.

In particular, polyester resins and polycarbonate resins can be suitably used. In addition, poly-N-vinyl carbazole having its own charge transporting ability can also be used as a binder.

The structure of the photoreceptor is such that a charge generating substance and a charge transporting substance are contained in the same layer on a conductive support as shown in FIG. 1, and on a conductive support as shown in FIG. There are a charge-generating layer containing a charge-generating substance, a charge-transporting layer containing a charge-transporting substance laminated thereon, and a charge-generating layer and a charge-transporting layer laminated in reverse. Any of the photoreceptors having the above configuration is effective for the present invention,
The laminated photoreceptor shown in FIG. 2 is preferable in that excellent electrophotographic characteristics can be obtained.

 The structure of the photoconductor will be described in more detail with reference to FIG.

As the conductive support, a metal plate of aluminum, copper, zinc, or the like, a plastic sheet or plastic film of polyester, or the like, on which a conductive material such as aluminum or SnO ₂ is deposited, or a paper or resin that has been subjected to conductive treatment is used. Is done.

To form the charge generation layer, a method of vacuum-depositing a charge generation substance on a conductive support, a method of applying and drying a solution of the charge generation substance, a method of applying and drying a fine particle dispersion of the charge generation substance, etc. The charge generation layer can be formed by using the charge generation material and selecting an arbitrary method. The thickness of the charge generation layer is preferably 0.01 to 5 μm,
More preferably, it is 0.05 to 2μ. This thickness is 0.01μ
If it is less than 5 μm, the generation of electric charge is not sufficient, and if it exceeds 5 μm, the residual potential is high, which is not practically preferable.

The charge transport layer is a mixture of at least one stilbene compound of the present invention and the binder dissolved in a suitable organic solvent,
It is formed by coating and drying. A charge transport material other than the stilbene compound of the present invention may be added to the charge transport layer, and used in combination with the compound of the present invention. The charge transport layer contains a charge transport material in an amount of 10 to 95% by weight, preferably 39 to 90% by weight. When the amount of the charge transporting substance is less than 10% by weight, the charge is hardly transported.

The thickness of the charge transport layer is preferably 3 to 50 μm, more preferably 5 to 30 μm, and the thickness is 3 μm.
If it is less than 50 μm, the charge amount is insufficient, and if it exceeds 50 μm, the residual potential is high, which is not preferable for practical use.

In addition, an intermediate layer can be provided between the photosensitive layer and the conductive support, but the material is suitably polyamide, nitrocellulose, casein, polyvinyl alcohol, and the like.
The thickness is preferably 1 μm or less.

As described above, the electrophotographic photoreceptor of the present invention includes the stilbene compound of the general formula (I), the conductive support, the charge generating substance, the binder, and the like.
Other components of the photoreceptor are not particularly limited as long as they have a function as components of the photoreceptor.

[Action and effect]

The electrophotographic photoreceptor of the present invention has high sensitivity by using the stilbene compound represented by the general formula (I) as a charge transporting substance and has excellent performance which does not deteriorate in repeated use.

EXAMPLES Hereinafter, 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 Synthesis of Exemplified Compound No. 1 The following structural formula 25 g of a compound represented by N, N-dimethylformamide 100 m
Then, 23 g of phosphorus oxychloride was added dropwise at 0 ° C.
After keeping the temperature at 0 ° C. for 1 hour, the temperature was raised to 70 ° C., and the mixture was further stirred for 1 hour. The reaction solution was poured into 500 ml of water and stirred for 1 hour.
The precipitated solid was collected by filtration, dried, and purified by column chromatography to obtain the following structural formula 12 g of the aldehyde compound represented by was obtained. Next, 2.9 g of the aldehyde compound thus obtained and 3.1 g of a phosphonate represented by the following structural formula The presence of _{t-C 4 H 9 OK1.2g,} N, N- dimethylformamide 60 ml, and reacted for 4 hours at room temperature, which was discharged into water 200 ml, the precipitated crystals were filtered, washed with water, dried Column purification (silica gel, using a mixed solvent of hexane: toluene = 2: 1) gave pale yellow crystals 3.9. This was confirmed to be Exemplified Compound No. 1 by elemental analysis.

Elemental analysis value CHN Calculated value (%) 90.87 5.87 3.26 Actual value (%) 90.95 5.80 3.22 Production Example 2 Synthesis of Exemplified Compound No. 5 2.8 g of aldehyde compound represented by the following structural formula And 1.6 g of a phosphonate represented by the following structural formula Was reacted in 60 ml of N, N-dimethylformamide at room temperature for 4 hours in the presence of 0.6 g of t-CHOK, discharged into 200 ml of water, and the precipitated crystals were collected by filtration, washed with water, dried and purified by column purification. (Silica gel, mixed solvent of hexane: toluene = 2: 1) was used to obtain 2.2 of pale yellow crystals. This was confirmed to be Exemplified Compound No. 5 by elemental analysis.

Elemental analysis value CHN Calculated value (%) 89.96 5.92 4.11 Actual value (%) 89.82 5.90 4.09 Production Example 3 Synthesis of Exemplified Compound No. 31 2.8 g of aldehyde compound represented by the following structural formula And 3.1 g of a phosphonate represented by the following structural formula The presence of _{t-C 4 H 9 OK1.2g,} N, N- dimethylformamide 60 ml, and reacted for 4 hours at room temperature, which was discharged into water 200 ml, the precipitated crystals were filtered, washed with water, dried And column purification (using a mixed solvent of silica gel and hexane: toluene = 2: 1) to obtain 3.6 of pale yellow crystals. This was confirmed to be Exemplified Compound No. 31 by elemental analysis.

Elemental analysis value CHN Calculated value (%) 89.27 5.62 3.25 Actual value (%) 89.23 5.60 3.22 Production Example 2 Synthesis of exemplified compound No. 35 2.8 g of aldehyde compound represented by the following structural formula And 1.6 g of a phosphonate represented by the following structural formula Was reacted in 60 ml of N, N-dimethylformamide at room temperature for 4 hours in the presence of 0.6 g of t-C ₄ H ₉ OK, discharged into 200 ml of water, and the precipitated crystals were collected by filtration, washed with water and dried. Column purification (silica gel, using a mixed solvent of hexane: toluene = 2: 1) gave pale yellow crystals 2.3. This was confirmed to be Exemplified Compound No. 35 by elemental analysis.

Elemental analysis value Calculated value of CHN (%) 87.95 5.61 4.10 Actual value (%) 87.93 5.59 4.08 Example 1 Polyester resin (manufactured by Toyobo, trade name "Byron 20")
0 ") 0.5 g, disazo dye 0.5 g represented by the following structural formula
(CG-1) (However, Expression B is It is. ) And 50 g of tetrahydrofuran were ground and mixed by a ball mill, and the obtained dispersion was applied to an aluminum plate using a wire bar, and dried at 80 ° C for 20 minutes to form a charge generation layer of about 0.5 µ.

Exemplified compound No. 11 g, polycarbonate resin (trade name “PANLITE K-1300” manufactured by Teijin Chemicals Ltd.)
A solution prepared by dissolving 1 g of chloroform in 10 parts of chloroform was applied using a wire bar, and dried at 80 ° C. for 30 minutes to form a charge transport layer having a thickness of about 18 μ. did.

Electrostatic copying paper test equipment (model manufactured by Kawaguchi Electric Works, Ltd.)
EPA-8100) was charged by corona discharge of the applied voltage -6KV the photoconductor was measured using a surface potential V ₀ at that time, then left in place for two seconds dark measuring the surface potential V ₂ at that time,
Further, when the surface illuminance of the photoreceptor is 51 ux, light from a halogen lamp (color temperature: 2856 ゜ K) is irradiated, and the surface potential becomes V.
Measure the time to become 1/2 of ₂ and calculate the half-life exposure amount E1 / 2 (1ux · se
c) was calculated. The surface potential V ₁₂ after 10 seconds of light irradiation, that is, the residual potential was measured. Further, the operation of charging exposure was repeated 1000 times.

Example 2 Disazo dye represented by the following structural formula (CG-2) (However, B in the formula is It is. ) Was used as a charge generating substance, and Exemplified Compound No. 1 was used as a charge transporting substance, except that a photoreceptor was prepared in the same manner as in Example 1 and the same measurement was performed.

Example 3 Disazo dye represented by the following structural formula (CG-3) (However, B in the formula is It is. ) Was used as a charge generating substance, and Exemplified Compound No. 1 was used as a charge transporting substance, except that a photoreceptor was prepared in the same manner as in Example 1 and the same measurement was performed.

Example 4 A tetrakisazo dye represented by the following structural formula (CG-
4) (However, A in the formula is It is. ) Was used as the charge generating substance, and Exemplified Compound No. 1 was used as the charge transporting substance, except that the preparation was performed in the same manner as in Example 1 and the same measurement was performed.

Example 5 A sample was prepared in the same manner as in Example 1 except that τ-phthalocyanine (CG-4) was used as a charge generating substance and Exemplified Compound No. 1 was used as a charge transporting substance, and the same measurement was performed.

Examples 6 to 30 Photoconductors were prepared in the same manner as in Example 1 except that the charge generating substance and the charge transporting substance were changed, and the same measurement was performed.

Table 15 shows the combinations of the charge generating substances and the charge transport substances used and the measurement results together with the measurement results of Examples 1 to 5.

Comparative Example 1 Except that the above disazo dye (CG-3) was used as a charge generating substance and 2,5-bis (4-diethylaminophenyl (-1.3,4, -oxadiazole (CT-1)) was used as a charge transporting substance. A photoreceptor was prepared and the same measurement was performed in the same manner as in Example 1. Table 15 shows the measurement results.

Examples 31 to 33 The photoreceptors prepared in Examples 1, 5 and 8 were respectively copied by using a commercially available electrophotographic copying machine. was gotten.

As described above, it can be said that the electrophotographic photoreceptor using the stilbene compound of the present invention has high sensitivity, stable performance even after repeated use, and excellent durability.

The photoreceptor of the present invention can be used not only for an electrophotographic copying machine but also for various printers and electrophotographic plate making systems that apply the electrophotographic principle.

[Brief description of the drawings]

FIG. 1 and FIG. 2 are cross-sectional views showing a configuration example of an electrophotographic photosensitive member. 1 and 2 are as follows. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 4,4 '... Photosensitive layer 2 ... Charge generation material 5, ... Charge transport layer 3 ... Charge transport material, 6 ... Charge generation layer

Claims (1)

(57) [Claims] 1. A photosensitive layer on a conductive support, wherein the compound represented by the general formula (I) (Wherein, Ar ¹ and Ar ² are unsubstituted or substituted arylene groups, Ar ³ , Ar ⁴ , Ar ⁵ , and Ar ⁶ are unsubstituted or substituted aryl groups, and R ¹ and R ² are unsubstituted or substituted. A substituted alkyl group, an aralkyl group or an aryl group, R ¹ and R ² may be bonded to each other, and X is an oxygen atom, a sulfur atom or R ³ and R ⁴ are a hydrogen atom, an alkyl group or an aryl group, and R ³ and R ⁴ may be bonded to each other. n represents an integer of 1 or 2. However, Is bonded to Ar ^{3 to} Ar ⁶ . A photosensitive member for electrophotography, comprising a compound represented by the formula: