JPH0339306B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a functionally separated photosensitive layer containing a specific α-phenylstilbene compound in the photosensitive layer. [Prior Art] Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been used as photoconductive materials for photoreceptors used in electrophotography. The "electrophotographic method" referred to here generally refers to a method in which a photoconductive photoreceptor is first charged in a dark place, for example, by corona discharge, and then exposed imagewise to selectively dissipate the charge only in the exposed areas. to obtain an electrostatic latent image, and this latent image area is developed and visualized with electrostatic fine particles (toner) consisting of a coloring material such as a dye or pigment and a binder such as a polymer substance to form an image. This is one of the most widely used image forming methods. The basic characteristics required of the photoreceptor in such electrophotography are (1) ability to be charged to an appropriate potential in the dark, (2) low charge dissipation in the dark, (3) For example, the charge can be quickly dissipated by light irradiation. Incidentally, it is a fact that each of the above-mentioned inorganic substances has many advantages, but also has various disadvantages. For example, selenium, which is currently widely used, fully satisfies conditions (1) to (3) above, but the manufacturing conditions are difficult, the manufacturing cost is high, it is not flexible, and it cannot be processed into a belt shape. It also has disadvantages, such as being difficult to handle and being sensitive to heat and mechanical shock, requiring careful handling. Cadmium sulfide and zinc oxide are used as photoreceptors by being dispersed in a resin as a binder, but they cannot be used as is because of mechanical drawbacks such as smoothness, hardness, tensile strength, and abrasion resistance. cannot be used. In recent years, electrophotographic photoreceptors using various organic materials have been proposed in order to eliminate the drawbacks of these inorganic materials, and some of them have been put into practical use. For example, poly N-vinylcarbazole and 2,4,
7-trinitrofluoren-9-one (described in U.S. Pat. No. 3,484,237), a photoreceptor made by sensitizing poly-N-vinylcarbazole with a pyrylium salt dye (Japanese Patent Publication No. 1973- 25658), a photoconductor whose main component is an organic pigment (described in JP-A-47-37543), a photoconductor whose main component is a eutectic complex consisting of a dye and a resin (JP-A-47-37543) −
(described in Publication No. 10735). [Problem to be solved by the invention] These photoreceptors have excellent characteristics and are considered to be of high practical value, but in electrophotography, various requirements for photoreceptors must be taken into consideration. The reality is that we have not yet obtained anything that satisfactorily satisfies these requirements. However, all of the photoreceptors mentioned so far differ depending on the purpose or manufacturing method, but in general, good characteristics can be obtained by using excellent photoconductive materials. be. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photoreceptor which can overcome the various drawbacks of the conventional photoreceptors mentioned above and fully satisfy the conditions required in electrophotography. Another object of the present invention is to provide an electrophotographic photoreceptor that is easy to manufacture, relatively inexpensive, and has excellent durability. [Means for Solving the Problem] The present inventor has proposed a charge transport system in a photoreceptor that combines a charge generating material with a large function of generating charges upon light irradiation and a charge transport material with a large function of transporting the generated charges. We researched and considered substances. The charge transporting substance must have a large ability to transport charges, but conversely, it must generate little or preferably no charge when irradiated with light, and must be able to sufficiently transmit the irradiated light to the charge-generating substance. No. As a result, the following general formula (In the formula, A is

[Formula] 9-anthryl group, or substituted or unsubstituted N-
Indicates an alkylcarbazolyl group, R ¹ is a hydrogen atom,
Indicates an alkyl group or a phenyl group. R ² represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, R ³ and R ⁴ represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, or R ³ , R ⁴ may join together to form a ring. n is an integer of 0 or 1. The present invention has been completed in which an α-phenylstilbene compound represented by the following formula functions effectively as a charge transporting substance in a functionally separated photosensitive layer of an electrophotographic photoreceptor and provides high sensitivity. That is, the present invention provides an electrophotographic photoreceptor in which a functionally separated photosensitive layer containing a combination of a charge-generating substance and a charge-transporting substance is provided on a conductive support, wherein the charge-transporting substance is represented by the above general formula. α
- It is characterized by using a phenylstilbene compound. The invention will now be explained in more detail with reference to the accompanying drawings. FIGS. 1 and 2 are cross-sectional views of two typical examples of photoreceptors according to the present invention, and the numbers assigned thereto are 1 for the conductive support, 2',
2'' represents a photosensitive layer, 3 represents a charge generating substance, 4 represents a charge transporting medium or charge transporting layer, and 5 represents a charge generating layer. α- represented by the above general formula used in the present invention
The phenylstilbene compound has the following general formula [In the formula, R represents a lower alkyl group] A 1,1-diphenyl derivative represented by the following general formula (In the formula, A and R ¹ are the same as defined in the general formula above.) It can be obtained by reacting with a carbonyl compound represented by the following formula. Substituents for the substituted aralkyl and substituted aryl groups in R ³ and R ⁴ in the general formula of the present invention include lower alkyl groups, lower alkoxy groups, aryloxy groups, halogen atoms, lower dialkylamino groups, hydroxy groups, carboxyl groups, and its ester, nitro group, acetyl group, or cyano group. Next, a manufacturing example will be shown. Production example Diethyl 1,1-diphenylmethylphosphonate
6.50 g (0.021 mol) and 5.84 g (0.021 mol) of 4-N,N-diphenylaminobenzaldehyde were dissolved in 40 ml of N,N-dimethylformamide, and 2.83 g (0.025 mol) of potassium t-butoxide was dissolved in 40 ml of N,N-dimethylformamide.
mol) was added over 20 minutes at 21-33°C. After stirring at room temperature for 4 hours, the reaction mixture was poured into 80 ml of ice water, and the resulting precipitate was collected by filtration, washed with water, and dried to obtain 8.20 g (yield: 90.6%) of a crude product. After recrystallization from a mixed solvent of toluene and ethanol, the obtained pale yellow needle crystals were collected by filtration, washed with methanol, and dried to give α-phenyl-4′-N,
N-diphenylaminostilbene (melting point 94.0~
95.0℃) was obtained. Specific examples of the α-phenylstilbene compounds thus obtained are shown in Table 1 below.

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[Table] The structure of the functionally separated photosensitive layer of the present invention can be used as shown in FIGS. 1 and 2. The photoreceptor shown in FIG. 1 has a photosensitive layer 2' provided on a conductive support 1, in which charge-generating material particles 3 are dispersed in a charge transport medium 4 made of an α-phenylstilbene compound and a binder. It is something that
The α-phenylstilbene compound here forms a charge transport medium together with the binder (or binder and plasticizer), while the charge generating material particles 3 (charge generating material particles such as inorganic or organic pigments) carry a charge. Generate carrier. In this case, the charge transport medium 4 is mainly responsible for receiving charge carriers generated by the charge generating material particles 3 and transporting them. The basic condition for this photoreceptor is that the absorption wavelength regions of the charge generating substance and the α-phenylstilbene compound do not overlap with each other, mainly in the visible region. This is because in order to efficiently generate charge carriers in the charge generating material particles 3, it is necessary to transmit light to the surface of the charge generating material particles. The α-phenylstilbene compound represented by the general formula () has almost no absorption in the visible region, generally absorbs light in the visible region, and is particularly effective when combined with charge-generating material particles 3 that generate charge carriers. Their characteristic is that they act as charge-carrying material particles. The photoreceptor in FIG.
and a charge transport layer 4 containing an α-phenylstilbene compound and a binder.
is provided. In this photoreceptor, light transmitted through the charge transport layer 4 reaches the charge generation layer 5,
The generation of charge carriers takes place in that region, while the charge transport layer 4 receives charge carrier injection and transports them, and the generation of charge carriers necessary for optical attenuation is
The transport of the charge carriers is carried out by the charge-generating material particles 3, and the transport of the charge carriers is carried out by the charge-transporting layer 4 (in which an α-phenylstilbene compound mainly acts). This mechanism is similar to the explanation given for the photoreceptor shown in FIG. Furthermore, it will be easily understood that the stacking order of the charge generation layer 5 and the charge transport layer 4 may be reversed. In order to produce the photoreceptor shown in FIG. The photosensitive layer 2' may be formed by coating it on the support 1 and drying it. The thickness of the photosensitive layer 2' is 3 to 50 μm, preferably 5 μm.
~20 μm is appropriate. α− in the photosensitive layer 2′
The amount of phenylstilbene compound is 10-95% by weight,
Preferably, the amount is 30 to 90% by weight, and the amount of the charge generating substance 3 in the photosensitive layer 2' is 0.1 to 50% by weight.
Preferably it is 1 to 20% by weight. Charge generating substance 3
Examples of organic pigments include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium sulfide-selenium α-silicon, and organic pigments such as CI Pigment Blue 25 (Color Index).
CI21180), CI Pigment Red 41
(CI21200), Cia Shit Dred 52
(CI45100), CI Basic Cred 3
(CI45210), Azo pigment with carbazole bone core (described in JP-A-53-95033), Azo pigment with distyrylbenzene bone core (JP-A-53-133445)
(described in Japanese Unexamined Patent Publication No. 132347/1983), an azo pigment having a triphenylamine bone core (described in Japanese Patent Application Laid-Open No. 132347/1983),
Azo pigments having dibenzothiophene bone cores (described in JP-A No. 54-21728), azo pigments having oxadiazole bone cores (described in JP-A-54-12742), azo pigments having fluorenone bone cores. Pigment (described in JP-A-54-22834), azo pigment with bisstilbene bone core (described in JP-A-54-17733), azo pigment with distyryloxadiazole core (described in JP-A-54-17733), Azo pigments such as azo pigments having a distyrylcarbazole bone core (described in JP-A-54-14967), phthalocyanine pigments such as C.I. Pigment Blue 16 (CI74100), e.g. C.I. Examples include indigo pigments such as Butt Brown 5 (CI73410) and CI Butt Dye (CI73030), and perylene pigments such as Argo Scarlet B (manufactured by Bayer) and Indus Thread Scarlet R (manufactured by Bayer). Note that these charge generating substances may be used alone or in combination of two or more types. Furthermore, in order to produce the photoreceptor shown in FIG. 2, a charge-generating substance is vacuum-deposited on a conductive support 1, or fine particles 3 of a charge-generating substance are deposited in a suitable form with a binder dissolved therein if necessary. The charge generation layer 5 is formed by applying a dispersion in a suitable solvent and drying it, and if necessary, performing surface finishing and film thickness adjustment by buffing or other methods. 1 on top
The charge transport layer 4 may be formed by applying a solution in which a species or two or more kinds of α-phenylstilbene compounds and a binder are dissolved and drying. The charge generating material used to form the charge generating layer 5 is the same as that used in the description of the photosensitive layer 2'. The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm.
m or less, and the thickness of the charge transport layer 4 is 3 to 50 μm.
A suitable thickness is preferably 5 to 20 μm. When the charge generation layer 5 is of a type in which charge generation substance fine particles 3 are dispersed in a binder, the proportion of the charge generation substance fine particles 3 in the charge generation layer 5 is preferably 10 to 95% by weight. It is about 50 to 90% by weight. Further, the amount of the α-phenylstilbene compound in the charge transport layer 4 is 10 to 95% by weight, preferably 30 to 90% by weight.
It is. In the production of any of these photoreceptors, a metal plate or foil made of aluminum or the like, a plastic film deposited with a metal such as aluminum, or paper subjected to conductive treatment is used as the conductive support 1. As the binder, condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide are used. , any insulating and adhesive resin can be used.
A plasticizer may be added to the binder if necessary, and examples of such plasticizers include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. Furthermore, the photoreceptor obtained in the above manner has
An adhesive layer or barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the film thickness is preferably 1 μm or less. To make a copy using the photoreceptor of the present invention, the photoreceptor surface is charged and exposed, then developed and, if necessary, transferred to paper or the like. The photoreceptor of the present invention has excellent advantages such as high sensitivity and flexibility. Examples are shown below. In the following examples, all parts are by weight. Example 1 76 parts of Diane Blue (CI Pigment Blue 25, CI 21180) and 2 parts of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) were used as charge generating substances.
% tetrahydrone furan solution and 3700 parts of tetrahydrofuran were ground and mixed in a ball mill,
The resulting dispersion was applied using a doctor blade onto the aluminum surface of a conductive support made of a polyester base coated with aluminum vapor, and air-dried to form a charge generation layer with a thickness of about 1 μm. On the other hand, α-phenyl-4′-N,
2 parts of N-diphenylaminostilbene, 2 parts of polycarbonate resin (Panlite K1300, manufactured by Teijin Ltd.)
1 part and 16 parts of tetrahydrofuran were mixed and dissolved to form a solution, which was applied onto the charge generation layer using a doctor blade, dried at 80°C for 2 minutes, and then dried at 105°C for 5 minutes to a thickness of about 20 μm. Photoreceptor No. 1 was prepared by forming charge transport. Examples 2 to 35 Photoreceptor No. 2 was prepared in the same manner as in Example 1 except that the charge generating substance and the charge transporting substance (α-phenylstilbene compound) were replaced with those shown in Table 2.
2 to 35 were created.

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[Table] Example 36 On an aluminum plate having a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of about 1 μm to form a charge generation layer. Next, 2 parts of α-phenylstilbene compound No. 39, 3 parts of polyester resin (Polyester Adhesive 49000 manufactured by Dupont) and 45 parts of tetrahydrofuran were mixed and dissolved to prepare a charge transport layer forming liquid, and this was added to the above solution. Apply it on the charge generation layer (selenium vapor deposition layer) using a doctor blade,
After air drying, dry under reduced pressure to a thickness of approximately 10 μm.
photoreceptor No. of the present invention.
Got 36. Example 37 Perylene pigment instead of selenium A charge generation layer (however, the thickness is about 0.3 μm) was formed using α-phenylstilbene compound No. 39.
Photoreceptor No. 37 was prepared in exactly the same manner as in Example 36, except that photoreceptor No. 4 was used instead of photoreceptor No. 4. Example 38 A mixture of 1 part of Diane Blue (same as that used in Example 1) and 158 parts of tetrahydrofuran was ground and mixed in a ball mill, and then
Add 12 parts of α-phenylstilbene compound No. 39 and 18 parts of polyester resin (Polyester Adhesive 49000 manufactured by Dupont), and then mix the resulting photosensitive layer forming liquid with a doctor onto an aluminum vapor-deposited polyester film. Apply using a blade,
Photoreceptor No. 38 of the present invention was prepared by drying at 100° C. for 30 minutes to form a photosensitive layer with a thickness of about 16 μm. Comparative Example Reference photoreceptors 1 to 3 were prepared in the same manner as in Example 5, except that the charge transport material was replaced with the following material. Photoconductors Nos. 1 to 38 and reference photoconductors 1 to 3 thus produced were tested using a commercially available electrostatic copying paper tester (Model SP428 manufactured by KK Kawaguchi Electric Seisakusho).
After charging by corona discharge of 6KV or +6KV for 20 seconds, leave it in a dark place for 20 seconds and measure the surface potential Vpo (volt) at that time. The time (seconds) required for the surface potential to become 1/2 of Vpo was determined, and the exposure amount E1/2 (lux seconds) was calculated. The results are shown in Table 3. Further, each of the above-mentioned photoreceptors is charged using a commercially available electrophotographic copying machine, and then light is irradiated through the original image to form an electrostatic latent image, which is developed using a dry developer. When the resulting image (toner image) was electrostatically transferred onto plain paper and fixed, a clear transferred image was obtained. A similarly clear transferred image was obtained when a wet developer was used as the developer.

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[Table] * No optical attenuation was observed.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views enlarged in the thickness direction of an electrophotographic photoreceptor according to the present invention. 1... Conductive support, 2', 2''... Photosensitive layer, 3
. . . charge generation material particles; 4 is a charge transport medium or charge transport layer; and 5 is a charge generation layer.

Claims (1)

[Claims] 1. A functionally separated photosensitive material comprising at least particles of a charge-generating substance dispersed in a charge-transporting medium comprising a charge-transporting substance represented by the following general formula and a resin binder on a conductive support. An electrophotographic photoreceptor characterized by having a layer. (wherein A is [Formula] 9-anthryl group, or substituted or unsubstituted N-
Indicates an alkylcarbazolyl group, R ¹ is a hydrogen atom,
Indicates an alkyl group or a phenyl group. R ² represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom; R ³ and R ⁴ represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group ^{; 4} may join together to form a ring. n is an integer of 0 or 1. ) 2 A functionally separated photosensitive layer formed by laminating a charge generation layer and a charge transport layer consisting of a charge transport substance represented by the following general formula and a resin binder on a conductive support. Characteristic electrophotographic photoreceptor. (wherein A is [Formula] 9-anthryl group, or substituted or unsubstituted N-
Indicates an alkylcarbazolyl group, R ¹ is a hydrogen atom,
Indicates an alkyl group or a phenyl group. R ² represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, R ³ and R ⁴ represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, or R ³ , R ⁴ may join together to form a ring. n is an integer of 0 or 1. )