JPH0441337B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more specifically,
The present invention relates to an electrophotographic photoreceptor in which a photosensitive layer formed on a conductive support contains a specific compound (amidine compound) as a charge transporting substance. 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. At least an electrostatic latent image is obtained, and this latent image is treated with a dye called toner.
It is one of the image forming methods in which an image is visualized using a developing means using electrostatic fine particles made of a colorant such as a pigment and a binder such as a polymeric substance. 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. It is true that the conventionally used inorganic materials have many advantages, but also have various disadvantages. For example, selenium, which is currently widely used, satisfies conditions (1) to (3) above, but
It also has drawbacks such as difficult manufacturing conditions, high manufacturing costs, lack of flexibility, difficulty in processing it into a belt shape, and sensitivity 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), poly-N-vinylcarbazole sensitized with a pyrylium salt dye (described in Japanese Patent Publication No. 25658/1983). ), a photoreceptor whose main component is an organic pigment (Japanese Unexamined Patent Publication No. 1983
-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (Japanese Patent Application Laid-Open No. 10735/1983)
(described in the publication). These photoreceptors have excellent properties and are considered to be of high practical value, but considering the various requirements for photoreceptors in electrophotography, it is still difficult to meet these requirements. The reality is that we are not getting anything that satisfies us. However, on the other hand, although these excellent photoreceptors differ depending on the purpose or manufacturing method, generally speaking, they exhibit excellent characteristics due to the use of an excellent photoconductive material. As a result of numerous studies and examinations of these photoconductive substances, the present inventor found the following general formulas () and (). (However, R ₁ is hydrogen, lower alkyl group, lower alkoxy group, halogen; R ₂ is lower alkyl group, aralkyl group, phenyl group; Ar ₁ is substituted or unsubstituted phenyl group, substituted or unsubstituted polycyclic aromatic group , or a substituted or unsubstituted heterocyclic group, where the substituent is a lower alkyl group, halogen, lower alkoxy group, lower alkylamino group, aralkylamino group, or substituted or unsubstituted phenylamino group). (However, R ₃ is hydrogen, lower alkyl group, lower alkoxy group, halogen; R ₄ is lower alkyl group, aralkyl group, phenyl group; R ₅ is lower alkyl group,
Aralkyl group, phenyl group; Ar ₂ represents a substituted or unsubstituted phenyl group, and the substituent here is a lower alkyl group, a lower alkoxy group, or a halogen. It has been discovered that the amidine compound represented by the following formula works effectively as a photoconductive material for electrophotographic photoreceptors and is also excellent as a charge transporting material. That is, the amidine compound, as described below,
It has been discovered that unexpected effects can be brought to the photoreceptor by combining it with various materials. The present invention was completed based on this knowledge. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor that eliminates all of the conventional drawbacks.Therefore, the present invention provides an electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive support. , the photosensitive layer is characterized in that the photosensitive layer contains an amidine compound represented by the general formula () or () described above as a charge transport substance. To explain the present invention in more detail below, the amidine compound represented by the general formula () or () can be produced with reference to Shin Jikken Kagaku Koza 14 , () 1608. That is, it is obtained by condensation reaction of N-substituted formanilide and aromatic amine or hydrazine using phosphorus oxychloride. Specific examples of the amidine compounds represented by the general formula () or () are as follows. As can be seen from these examples, in the definition of the general formula () or () above, specific examples of lower alkyl groups include methyl, ethyl, etc., and specific examples of lower alkoxy groups include methoxy, ethoxy, etc. It will be done. Compounds No. 1 to 126 in

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Compounds No.127-174 in

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【table】 Compounds No.175-192 in

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Compounds No.193-306 in

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[Table] The photoreceptor of the present invention contains at least one of the above-mentioned amidine compounds in the photosensitive layer. It can be used as shown in FIG. The photoreceptor shown in FIG. 1 has a conductive support 1 and a photosensitive layer 2 made of an amidine compound, a sensitizing dye, and a binder (resin). The photoreceptor shown in FIG. 2 has a charge generating substance 3 on a conductive support 1 and a charge transport medium 4 made of an amidine compound and a binder.
A photosensitive layer 2' is provided dispersed in the photosensitive layer 2'. The photoreceptor shown in FIG. 3 has a photosensitive layer 2'' formed on a conductive support 1, consisting of a charge generation layer 5 mainly containing a charge generation substance 3 and a charge transport layer 4 containing an amidine compound. In the photoreceptor shown in Figure 1, the amidine compound acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for light attenuation occur through the amidine compound. Since it has almost no absorption in the visible region, in order to form an image with visible light, it is necessary to sensitize it by adding a sensitizing dye that absorbs in the visible region. In this case, the amidine compound together with the overall agent (or binder and plasticizer) forms the charge transport medium, while the charge generating material, such as an inorganic or organic pigment, generates the charge carriers. The transport medium has the ability to accept and transport charge carriers mainly generated by the charge-generating substance.Here, the absorption wavelength ranges of the charge-generating substance and the amidine compound do not overlap, mainly in the visible region. is the basic condition.This is because in order to efficiently generate charge carriers in a charge-generating substance, it is necessary to transmit light to the surface of the charge-generating substance.The above-mentioned amidine compound is When combined with a charge-generating substance that has almost no absorption in the visible region and generally absorbs light in the visible region and generates charge carriers,
Its feature is that it works particularly effectively as a charge transport substance. In the photoreceptor shown in FIG. 3, light transmitted through the charge transport layer 4 reaches the charge generation layer 5, and charge carriers are generated in that region.On the other hand, the charge transport layer 4 receives charge carriers and transports them. The mechanism in which the charge carriers necessary for light attenuation are generated by the charge generation substance 3 and the charge carriers are transported by the charge transport medium (mainly in which the amidine compound of the present invention acts) is the first. This is the same as the case of the photoreceptor shown in FIG. Again, the amidine compound acts as a charge transport substance. To produce the photoreceptor shown in FIG. 1, an amidine compound is dissolved in a solution dissolved in a binder, and if necessary, a sensitizing dye is added to prepare a solution, and this solution is placed on a conductive support 1. The photosensitive layer 2 is formed by coating and drying. To produce the photoreceptor shown in FIG. 2, fine particles of a charge-generating substance are dispersed in a solution containing an amidine compound and a binder, and this is applied onto a conductive support 1 and dried to form a photosensitive layer 2'. form. In order to produce the photoreceptor shown in Fig. 3, a charge-generating substance is vacuum-deposited on a conductive support, or fine particles of a charge-generating substance are deposited in a suitable solvent in which a binder is dissolved as necessary. The charge generation layer 5 is applied and dried, and if necessary, the charge generation layer 5 is provided by finishing the surface by, for example, buffing or adjusting the film thickness. It is obtained by applying a solution containing a compound and a binder and drying it to provide a charge transport layer 4, thereby forming a laminated photosensitive layer 2''.
Application is carried out by conventional means, such as a doctor blade, wire bar, etc. The thickness of the photosensitive layer in FIGS. 1 and 2 is from 3 to 50 microns, preferably from 5 to 20 microns. Also the third
In the figure, the thickness of the charge generation layer 5 is 5μ or less, preferably 2μ or less, and the thickness of the charge transport layer 4 is 3 to 50μ, preferably 5 to 20μ. Further, in the photoreceptor shown in FIG. 1, the amount of the amidine compound in the photosensitive layer 2 is 30 to 70% by weight, preferably about 50% by weight. The amount of the sensitizing dye used to impart photosensitivity in the visible region to the photosensitive layer 2 is 0.1 to 5% by weight, preferably 0.5 to 3% by weight. In the photoreceptor shown in FIG. 2, the amount of the amidine compound in the photosensitive layer 2 is 10 to 95% by weight, preferably 30 to 90% by weight, and the proportion of the charge generating substance 3 is preferably 0.1 to 50% by weight. It is 1 to 20% by weight. Charge transport layer 4 in the photoreceptor of FIG.
The amount of the amidine compound in the photoreceptor is 10 to 95% by weight, preferably 30 to 90% by weight, as in the case of the photosensitive layer of the photoreceptor shown in FIG. Incidentally, in the production of any of the photoreceptors shown in FIGS. 1 to 3, a plasticizer can be used together with the binder. In the photoreceptor of the present invention, as the conductive support 1, a metal plate or metal foil made of aluminum or the like, a plastic film on which a metal such as aluminum is vapor-deposited, or paper subjected to conductive treatment is used. As a binder, polyamide, polyurethane,
Condensation resins such as polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide are used, but resins that are insulating and adhesive are All can be used. As the plasticizer, halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, etc. are used. The sensitizing dyes used in the photoreceptor shown in FIG. 1 include triarylmethane dyes such as brilliant green, Victoria blue B, methyl violet, crystal violet, and acid violet 6B;
6G, Rhodamine G Extra, Eosin S, Erythrosin, Rose Bengal, xanthene dyes such as fluorescein, thiazine dyes such as methylene blue, dianine dyes such as cyanine,
2,6-diphenyl-4-(N,N-dimethylaminophenyl)thiapyrylium perchlorate,
Examples include pyrylium dyes such as benzopyrylium salt (described in Japanese Patent Publication No. 48-25658). The charge generating substance 3 used in the photoreceptor shown in FIGS. 2 and 3 is an inorganic pigment such as selenium, selenium-tellurium, cadmium sulfide, or cadmium-selenium sulfide, and an organic pigment such as C.I. 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 styrylstilbene bone core (JP-A-53-133445)
(described in Japanese Patent Application Laid-open 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), 54-2129), azo pigments having distyrylcarbazole bone cores (described in JP-A-54-14967),
For example CI Pigment Blue 16 (CI74100)
Phthalocyanine pigments such as C.I. Butts Brown (CI73410) and C.I. Butts Dyed (CI73030); perylene pigments such as Argo Scarlet B (manufactured by Bayer) and Indance Scarlet R (manufactured by Bayer). pigments, etc. In addition, the photoreceptor obtained in the above manner has the following properties:
An adhesive layer or barrier layer can be provided between the conductive support 1 and the photosensitive layer 2, 2' or 2'', if necessary. Materials used for these layers include polyamide, nitrocellulose, Aluminum oxide, etc., and the film thickness is preferably 1μ or less.To copy using the photoreceptor of the present invention, the photoreceptor surface is charged and exposed, and then developed, and if necessary, paper is coated. The photoreceptor of the present invention satisfactorily achieves the above-mentioned purpose, and in addition, it has excellent advantages such as high sensitivity and flexibility.Next Examples are shown below. All parts here are parts by weight. Example 1 76 parts of Diane Blue (CI Pigment Blue 25, CI21180) as a charge generating substance, polyester resin (Byron 200, Toyobo Co., Ltd.) 2% of
1,260 parts of the tetrahydrofuran solution and 3,700 parts of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied using a doctor blade onto the aluminum surface of a conductive support made of an aluminum-deposited polyester base, and air-dried. A charge generation layer having a thickness of about 1 μm was formed. On the other hand, as a charge transport substance, 2 parts of the above No. 2 amidine compound, polycarbonate resin (Panlite
K1300 (manufactured by Teijin Ltd.) and 16 parts of tetrahydrofuran were mixed and dissolved to form a solution, and this was applied onto the charge generation layer using a doctor blade at 80°C for 2 minutes and then at 100°C for 5 minutes. Dry for minutes to form a charge transport layer with a thickness of about 20 μm, and then
No. 1 was produced. Examples 2 to 13 Photoreceptors Nos. 2 to 13 were prepared in exactly the same manner as in Example 1, except that the charge generating materials shown in Table 1 and the charge transporting materials described above were used.

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[Table] Example 14 On an aluminum plate having a thickness of approximately 300 μm, selenium was vacuum-deposited to a thickness of approximately 1 μm to form a charge generation layer. Next, as a charge transport substance, 2 parts of the above-mentioned amidine compound No. 198, 3 parts of polyester resin (manufactured by DuPont, Polyester Adhesive 49000), and 45 parts of tetrahydrofuran were mixed and dissolved to prepare a charge transport layer forming liquid. The above charge generation layer (selenium vapor deposited layer) was coated using a doctor blade, air dried, and then dried under reduced pressure to form a charge transport layer with a thickness of about 10 μm. .14 was made. Example 15 Perylene pigment used in place of selenium used in Example 14 was vacuum-deposited on an aluminum plate to a thickness of approximately 0.3μ to form a charge generation layer. Next, photoreceptor No. 15 was prepared in the same manner as in Example 14 except that the amidine compound No. 38 was used as the charge transporting substance. Example 16 A mixture of 1 part of Diane Blue (same as used in Example 1) and 158 parts of tetrahydrofuran was pulverized and mixed in a ball mill. Manufactured by Dupont, polyester adhesive
49000) was added and further mixed to prepare a photosensitive layer forming liquid. This was applied onto an aluminum vapor-deposited polyester film using a doctor blade and dried at 100° C. for 30 minutes to form a photosensitive layer with a thickness of about 16 μm, thereby producing photoreceptor No. 16 of the present invention. Examples 17 to 22 Photoreceptors Nos. 17 to 22 were prepared in exactly the same manner as in Example 16 using the charge generating substances and charge transporting substances shown in Table 2, respectively.

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[Table] Photoreceptors No. 1 to No. 22 obtained as above were tested at -6KV or +6KV using a commercially available electrostatic copying paper tester (manufactured by Kawaguchi Electric Seisakusho Co., Ltd., SP428 type).
After charging by corona discharge for 20 seconds,
Leave it in a dark place for 20 seconds, measure the surface potential Vpo (volts) at that time, then irradiate the photoreceptor surface with tungsten lamp light so that the illumination intensity is 20 lux, and the surface potential will be 1/2 of Vpo. The time (seconds) required for this to occur was determined, and the exposure amount E1/2 (lux seconds) was calculated. The results are shown in Table 3.

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[Table] After each of the photoreceptors described above was charged using a commercially available electrophotographic copying machine, light was irradiated through the original image to form an electrostatic latent image, and the image was developed using a dry developer. When the resulting 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 type developer was used as the developer.

[Brief explanation of drawings]

1 to 3 are cross-sectional views enlarged in the thickness direction of an electrophotographic photoreceptor according to the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2, 2', 2''... Photosensitive layer, 3... Charge generating substance, 4... Charge transporting medium or charge transporting layer, 5... Charge generating layer.

Claims (1)

[Claims] 1. The following general formula () or () is formed on a conductive support. (However, R ₁ is hydrogen, lower alkyl group, lower alkoxy group, halogen; R ₂ is lower alkyl group, aralkyl group, phenyl group; Ar ₁ is substituted or unsubstituted phenyl group, substituted or unsubstituted polycyclic aromatic group , or a substituted or unsubstituted heterocyclic group, where the substituent is a lower alkyl group, halogen, lower alkoxy group, lower alkylamino group, aralkylamino group, or substituted or unsubstituted phenylamino group). (However, R ₃ is hydrogen, lower alkyl group, lower alkoxy group, halogen; R ₄ is lower alkyl group, aralkyl group, phenyl group; R ₅ is lower alkyl group,
Aralkyl group, phenyl group; Ar ₂ represents a substituted or unsubstituted phenyl group, and the substituent here is a lower alkyl group, a lower alkoxy group, or a halogen. 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing an amidine compound represented by the following formula as a charge transporting substance.