JPS6235672B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel photoreceptor having a photosensitive layer containing as an active ingredient at least one hydrazone compound represented by the following general formula (). (However, Ar represents a fused polycyclic ring such as a substituted or unsubstituted naphthalene ring or anthracene ring; a substituted or unsubstituted heterocyclic ring such as a furan ring, a thiophene ring, a pyridine ring, or a carbazole ring; or a substituted or unsubstituted styryl group) ) Conventionally, in electrophotography, inorganic substances such as selenium, cadmium sulfide, and zinc oxide have been used as photoconductive materials for photoreceptors used. The "electrophotographic method" referred to here generally refers to a method in which a photoconductive photoreceptor is first charged in a dark place by, for example, corona discharge, and then imagewise exposed to selectively discharge the charge only in the exposed areas. As a result, an electrostatic latent image is obtained, and this latent image area is visualized using a developing means using electrostatic fine particles made of a coloring material such as a dye or pigment called a toner and a binder resin such as a polymeric substance, and the image is then visualized. This is one of the image forming methods. The basic characteristics required of a photoreceptor in such electrophotography are (1) ability to be charged to an appropriate potential in a dark place, (2) little discharge of charge in a dark place, and (3) ability to be quickly charged by light irradiation. Examples include discharging electric charges. 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, 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 and sensitive to heat and mechanical shock, requiring careful handling. Cadmium sulfide and zinc oxide are used in photoreceptors dispersed in binding resin, but the smoothness, hardness,
Since it has mechanical defects such as tensile strength and abrasion resistance, it cannot withstand repeated use as it is. Recently, 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
- Photoreceptor consisting of trinitrofluoren-9-one (US Patent No. 3,484,237), poly-N-vinylcarbazole sensitized with pyrylium salt dye (Nippon Patent Publication No. 48-25658), organic pigment as the main component (Japanese Patent Laid-Open No. 47-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (Japanese Patent Laid-Open No. 47-37543)
-10735). These photoreceptors certainly have excellent characteristics and are considered to be of high practical value, but considering the various requirements for photoreceptors from the viewpoint of the electrophotographic process, there are still The reality is that nothing that fully satisfies these requirements has been obtained. On the other hand, although these excellent photoreceptors differ depending on the purpose or manufacturing method, they generally exhibit excellent characteristics due to the use of excellent photoconductive materials. As a result of research on this type of photoconductive substance, the present inventors discovered that the hydrazone compound represented by the above general formula () functions effectively as a photoconductive substance for electrophotographic photoreceptors. That is,
As will be described later, it has been found that by combining hydrazone compound I with various materials, it is possible to provide a photoreceptor having unexpected effects and a surprisingly wide range of usefulness. The hydrazone compound of the general formula () used in the present invention is produced by a conventional method. That is, aldehydes of equal molecular weight and 1-benzyl-1-p-anishydrazine are condensed in alcohol by adding a small amount of acid (glacial acetic acid or mineral acid) as a condensing agent if necessary. It may be appropriate to carry out the reaction with a slight excess of hydrazine to improve yield and facilitate subsequent purification. Examples of compounds corresponding to the general formula () are as follows. The photoreceptor of the present invention contains the above-mentioned hydrazone compounds, and can take the forms shown in FIGS. 1 to 3 depending on how these hydrazone compounds are applied. The photoreceptor shown in FIG. 1 has a photosensitive layer 2 comprising a hydrazone compound I, a sensitizing dye, and a binding resin on a conductive support 1. The photoreceptor shown in FIG. The photoreceptor shown in FIG. 2 has a charge carrier generating material 3 on a conductive support 1.
A photosensitive layer 2' is provided in which the photosensitive layer 2' is dispersed in a charge transfer medium 4 made of a hydrazone compound I and a binding resin. The photoreceptor shown in FIG. 3 has a photosensitive layer 2'' consisting of a charge carrier generation layer 5 mainly containing a charge carrier generation substance 3 and a charge transfer layer 6 containing a hydrazone compound I on a conductive support 1. In the photoreceptor shown in Figure 1, hydrazone compound I acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for light attenuation are carried out through the hydrazone compound.However, hydrazone compound I is mostly in the visible range. Since it has no absorption, in order to form an image with visible light, it is necessary to sensitize it with a sensitizing dye that has absorption in the visible region.In the case of the photoreceptor shown in Figure 2, hydrazone compound I
together with the binder (and optionally plasticizer) form the charge transport medium, while the charge carrier generating material, such as an inorganic or organic pigment, generates the charge carriers. In this case, the charge transfer medium primarily has the ability to accept and transfer charge carriers generated by the charge carrier generating substance. The basic condition here is that the absorption wavelength regions of the charge carrier generating substance and the hydrazone compound I do not overlap with each other mainly in the visible region. This effectively converts charge carrier generating substances into
This is because it is necessary to transmit light to the surface of the charge carrier generating substance. The hydrazone compound I used in the present invention has almost no absorption in the visible region, generally absorbs light in the visible region, and works particularly effectively as a charge carrier transfer material when combined with a charge carrier generating material that generates charge carriers. This is its feature. In the photoreceptor shown in FIG. 3, light transmitted through the charge transfer layer 6 reaches the charge carrier generation layer 5, and charge carriers are generated there. It is something that receives and moves,
The mechanism in which the charge carriers necessary for light attenuation are generated by a charge carrier generating substance, and the charge carriers are transferred by a charge transfer medium (mainly acted by the hydrazone compound I of the present invention) is shown in Figure 2. The same is true for the photoreceptor. Again, the hydrazone compound I acts as a charge transfer substance. To prepare the photoreceptor shown in FIG. 1, hydrazone compound I is dissolved in a binder solution, and if necessary, a sensitizing dye is added thereto, and the solution is coated on a conductive support and dried. The photoreceptor shown in FIG. 2 can be prepared by dispersing fine particles of a charge carrier-generating substance in a solution containing a hydrazone compound I and a binder, and applying and drying this onto a conductive support. The photoreceptor shown in Fig. 3 can be prepared by vacuum-depositing a charge carrier generating substance on a conductive support, or by depositing fine particles of a charge carrier generating substance, if necessary, in a suitable solvent in which a binder is dissolved. After dispersion coating and, if necessary, surface finishing by a method such as buffing or adjusting the film thickness, a solution containing hydrazone compound I and a binder is coated thereon and dried. The application method is carried out by conventional means, such as a doctor blade or a wire bar. The thickness of the photosensitive layer in FIGS. 1 and 2 is about 3 to 50 microns, preferably 5 to 20 microns. Also the third
In the figure, the thickness of the charge carrier generation layer is 5μ or less.
Preferably, the thickness is 0.01 to 0.5μ, and the thickness of the charge transport layer is about 3 to 50μ, preferably 5 to 20μ. In the photoreceptor shown in FIG. 1, the proportion of hydrazone compound I in the photosensitive layer is suitably 30 to 70% by weight, preferably about 35 to 50% by weight, based on the photosensitive layer. The amount of the sensitizing dye used to impart photosensitivity in the visible region is 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the photosensitive layer. In the photoreceptor shown in FIG. 2, the proportion of hydrazone compound I in the photosensitive layer is 10 to 95% by weight, preferably 30 to 90% by weight.
and the proportion of charge carrier generating material is 50% by weight.
The content is preferably 1 to 20% by weight. The proportion of hydrazone compound I in the charge transfer layer of the photoreceptor shown in FIG. 3 is 10 to 95% by weight, preferably 30 to 90% by weight, as in the photosensitive layer of the photoreceptor shown in FIG. In addition, in producing any of the photoreceptors shown in FIGS. 1 to 3, plasticity can be used together with a binder. In the photoreceptor of the present invention, a metal plate or foil made of aluminum or the like, a plastic film coated with a metal such as aluminum, or paper treated to be electrically conductive is used as the conductive support. As a binder, polyamide, polyurethane, polyester, epoxy resin, polyketone,
Examples include condensation resins such as polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide, but any insulating and adhesive resin can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, the sensitizing dye used for the photoreceptor shown in Figure 1 is brilliant green, Victoria blue,
B, triarylmethane dyes such as methyl violet, crystal violet, acid violet 6B, rhodamine B, rhodamine
xanthene dyes such as 6G, Rhodamine G Extra, Eosin S, erythrosine, rose bengal, floretssen, thiazine dyes such as methylene blue, cyanine dyes such as cyanine,
2,6-diphenyl-4-(N,N-dimethylaminophenyl)thiapyrylium perchlorate,
Examples include pyrylium dyes such as benzopyrylium salts described in Japanese Patent Publication No. 48-25658. Examples of charge-generating materials used in the photoreceptors shown in FIGS. 2 and 3 include selenium, selenium-tellurium,
Examples of inorganic pigments such as cadmium sulfide and cadmium-selenium sulfide, and organic pigments include CI Pigment Blue 25 (Color Index CI
21180), CI Pigment Red 41 (CI
21200), CI Acid Dred 52 (CI
45100), CI Basic Cred 3 (CI
45210), Azo pigments with carbazole bone cores (JP-A-53-95966), Azo pigments with styrylstilbene bone cores (JP-A-53-133445), Azo pigments with triphenylamine bone cores (JP-A-53-133445) Azo pigments with dibenzothiophene bone cores (Japanese Patent Application Laid-open No. 54-21728), Azo pigments with oxadiazole bone cores (Japanese Patent Laid-Open No. 54-12742), Azo pigments with fluorenone bone cores Azo pigment (Japanese Patent Application Laid-open No. 54-22834), Azo pigment having a stilbene bone core (Japanese Patent Publication No. 54-20737), Azo pigment having a distyryloxadiazole bone core (Japanese Patent Publication No. 54-2129), Azo pigments such as Azo Pigments with Distyryl Carbazole Bones (Japanese Unexamined Patent Publication No. 14967/1987), Phthalocyanine pigments such as CI Pigment Blue 16 (CI 74100), such as CI Butt Brown 5 (CI
73410), CI Butt Dye (CI 73030), and perylene pigments such as Argo Scarlet B (manufactured by Bayer) and Indance Scarlet B (manufactured by Bayer). In any of the photoreceptors obtained as described above, an adhesive layer or a barrier layer may be provided between the conductive support and the photosensitive layer, if necessary. Suitable materials for these layers include polyamide, nitrocellulose, aluminum oxide, and the like, and the film thickness is preferably 1 μm or less. Copying using the photoreceptor of the present invention is accomplished by charging and exposing the surface of the photoreceptor layer, developing it, and, if necessary, transferring it to paper or the like. The photoreceptor of the present invention generally has excellent advantages such as high sensitivity and flexibility. Examples are shown below. Example 1 98 parts of Tesla hydrofuran were added to 2 parts of Diane Blue (CI 21180), and the mixture was pulverized and mixed in a ball mill to obtain a charge carrier-generating pigment liquid. This was applied onto a polyester film coated with aluminum using a doctor blade, and air-dried to form a charge carrier generation layer with a thickness of 0.5 μm. Next, a charge transfer layer forming liquid obtained by mixing and dissolving 2 parts of hydrazone represented by structural formula (2), 3 parts of polycarbonate resin (Panlite L manufactured by Teijin), and 45 parts of tetrahydrofuran was applied onto the above charge carrier generation layer. Apply with a doctor blade to 100℃ at 100℃.
A charge transfer layer having a thickness of about 10 μm was formed by drying for a minute, and a photoreceptor was fabricated. Regarding this photoreceptor, the electrostatic copying paper testing device (〓
Kawaguchi Electric Seisakusho, SP428 type) was used to perform -6kV corona discharge for 20 seconds to make it negatively charged, and then left in a dark place for 20 seconds to determine the surface potential Vpo.
(V), then irradiate the surface with light using a tungsten lamp so that the illumination intensity is 20 lux, find the time (seconds) until the surface potential becomes 1/2 of Vpo, and calculate the exposure amount. E1/2 (Lutx)
seconds) was calculated. The result is Vpo=-550V, E
1/2 = 7.5 lux seconds. Example 2

[Table] A charge carrier-generating pigment dispersion is obtained by pulverizing and mixing the liquid in a ball mill. This was applied onto a polyester film deposited with aluminum using a doctor blade, and dried for 5 minutes in a dryer at 80° C. to form a charge carrier generation layer with a thickness of 1 μm.
Next, a charge transfer layer forming liquid obtained by mixing and dissolving 2 parts of hydrazone represented by structural formula (3), 3 parts of polycarbonate resin (Panlite L), and 45 parts of tetrahydrofuran was applied onto the charge carrier generation layer with a doctor blade. The photoreceptor of the present invention was prepared by coating the photoreceptor using the following method and drying at 100° C. for 10 minutes to form a charge transfer layer with a thickness of about 10 μm. This photoreceptor was negatively charged in the same manner as in Example 1, and Vpo and E1/
2 was measured and found that Vpo=-850V and E1/2=4.5 Lux seconds. Examples 3 and 4 In the same manner as in Example 2, the charge-generating pigment and charge-transfer substance were changed, and the results shown in Table 1 were obtained.

[Table] Example 5 The photoreceptors obtained in Examples 1 to 4 were negatively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image to produce positively charged toner. The resulting image was electrostatically transferred to high-quality paper and fixed to obtain a clear image. A similarly clear image was obtained when a wet type developer was used as the developer. Example 6 On an aluminum plate with a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of 1 μm to form a charge carrier generation layer. Next, two parts of hydrazone represented by the structural formula (18), a polyester resin (manufactured by DuPont)
Mix and dissolve 3 parts of Polyester Adhesive 49000) and 45 parts of tetrahydrofuran to prepare a charge transfer layer forming liquid, apply this onto the charge carrier generation layer (selenium vapor deposited layer) using a doctor blade, and dry naturally. Thereafter, it was dried under reduced pressure to form a charge transfer layer with a thickness of about 10 μm, thereby obtaining a photoreceptor of the present invention. The Vpo and E1/2 of this photoreceptor were measured in the same manner as in Example 1. Vpo=-890V, E1/2
2 = 3.5 lux seconds. Example 7 Perylene pigment in place of selenium in Example 6 is vacuum deposited to a thickness of about 0.3μ to form a charge carrier generation layer. Next, a photoreceptor similar to that of Example 6 was prepared except that structural formula (9) was used as the charge transfer substance, and results were obtained in which Vpo=-730V and E1/2=9.0 Lux·sec. Example 8 A dry developer having a positively charged toner in which the photoreceptors obtained in Examples 6 and 7 were negatively charged using a commercially available copying machine and then irradiated with light through the original image to form an electrostatic latent image. The image was electrostatically transferred to high-quality paper and fixed to obtain a clear image. A similarly clear image was obtained when a wet type developer was used as the developer. Example 9 A mixture of 1 part of Chlordiane Blue and 158 parts of tetrahydrofuran was pulverized and mixed in a ball mill, and then mixed with 12 parts of a hydrazone compound represented by the structural formula (12), a polyester resin (polyester adhesive manufactured by Dupont), etc. 49000) and further mixed to obtain a photosensitive layer forming solution, which was applied onto an aluminum-deposited polyester film using a doctor blade, dried at 100°C for 30 minutes, and a photoreceptor with a thickness of about 16μ was formed. The photoreceptor of the present invention was fabricated by forming the photoreceptor of the present invention. Using the same device as used in Example 1, this photoreceptor was positively charged by +6kV corona discharge, and Vpo and E1/2 were similarly measured.Vpo=960V, E1/2=9.8 Lux・It was hot in seconds. Examples 10 to 12 Photoreceptors were prepared according to the same method as in Example 9 except that the charge carrier generating pigment and charge transfer substance were changed as shown in Table 2. The photoreceptor was subjected to the same measurements as in Example 1, and the results shown in Table 2 were obtained.

[Table] Example 13 The photoconductors obtained in Examples 9 to 12 were positively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image to form a negatively charged toner. The image was developed using a dry type developer, and the image was electrostatically transferred to high-quality paper and fixed to obtain a clear image. A similarly clear image was obtained when a wet type developer was used as the developer. Example 14 1 part of hydrazone represented by structural formula (4), 1 part of polycarbonate resin (Panlite L manufactured by Teijin), and 0.001 part of crystal violet were dissolved in 9 parts of 1,2-dichloroethane, and a wire was placed on paper whose surface was conductive. It was coated using a bar and dried at 100°C for 5 minutes to form a 6μ photoresist film. This photosensitive paper was positively charged to about 500V by corona discharge, exposed through the original at 200 lux for 1.5 seconds, and then developed with a wet developer to obtain an image faithful to the original.

[Brief explanation of the drawing]

1 to 3 are enlarged sectional views of a photoreceptor according to the present invention. 1... Conductive support, 2, 2, 2''... Photosensitive layer, 3... Charge carrier generating substance, 4... Charge transport layer, 5... Charge carrier generating layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a hydrazone compound represented by the following general formula () as an active ingredient on a conductive support. (However, Ar represents a fused polycyclic ring such as a substituted or unsubstituted naphthalene ring or anthracene ring; a substituted or unsubstituted heterocyclic ring such as a furan ring, a thiophene ring, a pyridine ring, or a carbazole ring; or a substituted or unsubstituted styryl group) )