JPS6255655B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor containing a fluorene compound as an active ingredient in a photosensitive layer. Conventionally, photoconductive materials for photoreceptors used in electrophotography include inorganic materials such as selenium, cadmium sulfide, and zinc oxide. The "electrophotographic method" referred to here generally involves first charging a photoreceptor in a dark place by corona discharge, and then exposing it to imagewise light to selectively discharge the charge only in the exposed areas to obtain an electrostatic latent image. This is one of the image forming methods in which an image is formed by visualizing this latent image area with a developer containing a coloring agent called a toner and electrostatic fine particles made of a binder resin. The basic characteristics required of a photoreceptor in photography 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) rapid release of charge by light irradiation. Although the inorganic substances conventionally used have many advantages, they also have various disadvantages.For example, selenium, which is currently widely used, has many advantages. Condition 3 is fully satisfied, but the manufacturing conditions are strict, which increases the manufacturing cost, it is difficult to process into a belt because it is not flexible, and it is sensitive to heat and mechanical shock. However, cadmium sulfide and zinc oxide are used dispersed in binder resins, but mechanical properties such as smoothness, hardness, tensile strength, and abrasion resistance are Due to their drawbacks, they cannot withstand repeated use as they are.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-
A combination of trinitro-9-fluorenone (U.S. Pat. No. 3,484,237), a sensitized poly-N-vinylcarbazole with a pyrylium salt dye (Japanese Patent Publication No. 48-25658), and an organic pigment as a main component. (Japanese Unexamined Patent Publication No. 47-37543), and one whose main component is a eutectic complex consisting of a dye and a resin (Japanese Unexamined Patent Publication No. 10735/1982). 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 electrophotographic processes, it is still difficult to fully meet these requirements. The reality is that we are not getting anything that satisfies us. On the other hand, although these excellent photoreceptors differ slightly depending on the purpose or manufacturing method, they generally exhibit excellent characteristics by using an excellent photoconductive material. As a result of researching this type of photoconductive substance from the above-mentioned viewpoints, the present inventors discovered that a fluorene compound represented by the following general formula works effectively as a photoconductive substance for electrophotographic photoreceptors. . That is, the compound of this general formula, as described later,
We have discovered that by combining various materials, we can provide photoreceptors with unexpected effects and surprisingly versatile utility. (However, R is hydrogen, C ₁ to C ₄ lower alkyl group,
Represents a _C1 to _C4 lower alkoxy group, halogen or nitro group. ) The fluorene compound of the general formula used in the present invention can be easily obtained by reacting 2,7-diaminofluorene with the corresponding benzyl halide in the presence of an alkali. Next, representative examples of the fluorene compounds obtained in this manner will be illustrated. The photoreceptor of the present invention contains the above-mentioned fluorene compounds, and can take the forms shown in FIGS. 1 to 3 depending on how these fluorene compounds are applied. The photoreceptor shown in FIG. 1 has a photosensitive layer 2 formed on a conductive support 1, comprising the fluorene compound, a sensitizing dye, and a binding resin. The photoreceptor shown in FIG. 2 has a photosensitive layer 2' on a conductive support 1, in which a charge carrier generating substance 3 is dispersed in a charge transfer medium 4 made of the fluorene compound and a binding resin. . The photoreceptor shown in FIG. 3 has a charge carrier generation layer 5 mainly composed of a charge carrier generation substance 3 and a charge transfer layer 4 containing the fluorene compound on a conductive support 1.
In the photoreceptor shown in FIG. 1, the fluorene compound acts as a photoconductive substance, and the generation and movement of charge carriers necessary for light attenuation occur through this fluorene compound. However, since this fluorene compound has almost no absorption in the visible range, it is necessary to sensitize it with a sensitizing dye that has absorption in the visible range for the purpose of forming an image. In the case of the photoreceptor shown in Figure 2, this fluorene compound forms a charge transport medium with a binder (and optionally a plasticizer);
On the other hand, charge carrier generating substances such as inorganic or organic pigments generate 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 fluorene 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 carrier generating material, it is necessary to transmit light to the surface of the charge carrier generating material. The fluorene compound of the present invention exhibits almost no absorption in the visible region, and has the feature that it functions particularly effectively as a charge transfer medium when combined with a charge carrier generating substance that generally absorbs light in the visible region and generates charge carriers. I have it. In addition, in the photoreceptor shown in FIG. 3, light transmitted through the charge transfer layer 4 reaches the charge carrier generation layer 5, where charge carriers are generated, while the charge transfer layer does not allow injection of charge carriers. The second mechanism is that the charge carriers necessary for photoattenuation are generated by a charge carrier generating substance, and the charge carriers are transferred by a charge transfer medium (mainly the fluorene compound of the present invention works). This is the same as the case of the photoreceptor shown in the figure.
Again, the fluorene compound acts as a charge transfer substance. To prepare the photoreceptor shown in FIG. 1, the fluorene compound is dissolved in a binder solution, and if necessary, a sensitizing dye is added to the solution.The solution is coated on the conductive support 1 and dried to form the photosensitive layer 2. All you have to do is form. To produce the photoreceptor shown in FIG. 2, fine particles of the charge carrier generating substance 3 are dispersed in a solution containing the fluorene compound and a binder, and this is applied onto the conductive support 1 and dried to form the photosensitive layer 2'. All you have to do is form. In the case of the photoreceptor shown in FIG. 3, the charge carrier generating substance 3 (a) is vacuum-deposited on the conductive support 1, or the fine particles of the charge carrier generating substance 3 (b) are placed in a solution containing a binder dissolved therein. The charge carrier generation layer 5 is formed by dispersing, applying and drying the layer, and if necessary, finishing the surface by buffing or adjusting the thickness, and then applying the fluorene compound and the binder thereon. The charge transfer layer 4 may be formed by applying and drying a solution containing the above. The application method is carried out by conventional means, such as a doctor blade or a wire bar. In the above photoreceptors, the thickness of the photosensitive layer is about 3 to 50 μm, preferably 5 to 50 μm for those shown in FIGS. 1 and 2.
20μ is appropriate. In addition, in the case of FIG. 3, the thickness of the charge carrier generation layer is 0.01 to 5μ, preferably 0.1 to 2μ.
The sum of .mu. and the thickness of the charge transport layer is about 3 to 50 .mu., preferably 5 to 20 .mu.. In the photoreceptor shown in FIG. 1, the appropriate proportion of the fluorene compound in the photosensitive layer is 30 to 70%, preferably about 50%, of the weight of the photosensitive layer. The sensitizing dye used to impart photosensitivity in the visible region accounts for 0.01 to 5% of the weight of the photosensitive layer, preferably
0.1-3% is appropriate. Next, the proportion of the fluorene compound in the photosensitive layer shown in FIG. Weight%. Further, in the photoreceptor shown in FIG. 3, the proportion of the fluorene compound in the charge transfer layer 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 any of the photoreceptors shown in FIGS. 1 to 3, a plasticizer can be used together with a binder. In the photoreceptor of the present invention, the conductive support may be a metal plate or metal foil such as aluminum, a plastic film on which metal such as aluminum is vapor-deposited,
Alternatively, conductive treated paper, plastic film, etc. may be used. Examples of binders include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, and polyacrylamide. In addition, any adhesive resin can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, the sensitizing dyes used in the photoreceptor shown in FIG.
Xanthene dyes such as 6G, Rhodamine G Extra, Eosin S, Erythrosin, Rose Bengal, Fluorethcene; Thiazine dyes such as methylene blue; Cyanine dyes such as cyanine;
Examples include pyrylium dyes such as 2,6-diphenyl-(N,N-dimethylaminophenyl)thiapyrylium perchlorate and benzopyrylium salts described in Japanese Patent Publication No. 48-25658. Examples of charge-generating substances used in FIGS. 2 and 3 include inorganic pigments such as selenium, selenium-tellurium alloy, cadmium sulfide, cadmium sulfide-selenium alloy, and C.I. Pigment Blue 25.
(CI21180), CI Pigment Red 41
(CI21200), CIA Dred 52
(CI45100), CI Basic Cred 3
(CI45210), an azo pigment with a carbazole skeleton (Japanese Patent Application No. 52-8740, 52-8741), an azo pigment with a styrylstilbene skeleton (Japanese Patent Application No. 52-8741),
No. 48859, No. 52-48860), azo pigments having a triphenylamine skeleton (Japanese Patent Application No. 52-45812, No. 52-48860);
52-46859), azo pigments having a dibenzothiophene skeleton (Japanese Patent Application Laid-Open No. 54-21728), azo pigments having an oxadiazole skeleton (Japanese Patent Laid-Open No. 54-12742),
Azo pigments having a fluorenone skeleton
22834), azo pigments with a stilbene skeleton (JP-A-54-20737, JP-A-52-8832), azo pigments with a distyryl oxadiazole skeleton (JP-A-54
-2129), azo pigments with a distyrylcarbazole skeleton (Japanese Patent Application No. 80116/1983, Patent Application No. 81791), C.I. Pigment Blue 16
Phthalocyanine pigments such as (CI74100), indigo pigments such as C.I. Butts Brown 5 (CI73410), C.I. Buttsto Dai (CI73030), Argo Scarlet B, Indance Scarlet R.
Examples include organic pigments such as perylene pigments such as . In any of the photoreceptors obtained as described above, an adhesive layer or a barrier layer can be provided between the conductive support and the photosensitive layer. Suitable materials for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the layer thickness is preferably about 0.1 to 1 .mu.m. To perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed in a conventional manner, then developed, and if necessary, the image is transferred to a transfer paper such as high-quality paper. The photoreceptor of the present invention generally has excellent advantages such as high sensitivity and flexibility. Examples are shown below. All parts are by weight. Example 1 98 parts of tetrahydrofuran was added to 2 parts of Diane Blue (CI21180), and the mixture was pulverized and mixed in a ball mill to obtain a charge carrier generation layer forming liquid. This is made of aluminum evaporated polyester film (thickness approx. 75cm).
μ) was coated with a doctor blade and air-dried to form a charge carrier generation layer with a thickness of 1 μ. Next, a charge transfer layer forming liquid prepared by mixing and dissolving 2 parts of Compound No. 2 fluorene compound, 3 parts of polycarbonate resin (Panlite L manufactured by Teijin), and 45 parts of tetrahydrofuran is applied onto the charge carrier generation layer using a doctor blade. Dry at 100℃ for 10 minutes to a thickness of approximately 10μ
A charge transfer layer was formed. Using a commercially available electrostatic copying paper tester, the resulting photoreceptor was negatively charged by applying -6KV corona discharge for 20 seconds, and then left in a dark place for 20 seconds to determine the surface potential Vpo (volts). ), then use a tungsten lamp to irradiate the surface of the photosensitive layer with light at an illuminance of 20 lux, find the time (seconds) until the surface potential becomes 1/2 of Vpo, and calculate the exposure amount E1/2 ( Lutx sec) was obtained. The result is Vpo=−
It was 930V, E1/2 = 3.5 lux seconds. Example 2 As a charge generating substance

Example 1 except that [Table] was pulverized and mixed in a ball mill to obtain a charge carrier generating liquid, and this was dried at 80°C for 5 minutes.
A charge carrier generation layer was formed in the same manner as described above. In addition, Example 1 except that the fluorene compound of Compound No. 4 was used instead of the fluorene compound of Compound No. 2.
A charge transport layer was formed in the same manner as described above. The Vpo of the photoreceptor obtained as above is −
720V, E1/2 was 5.9 Lux・sec. Example 3 As a charge carrier generating substance A photoreceptor was prepared in the same manner as in Example 2, except that Compound No. 1 fluorene compound was used as the charge transfer substance (fluorene compound), and Vpo=
−1100V, E1/2=10.3 lux·sec was obtained. Example 4 As a charge carrier generating substance A photoreceptor was prepared in the same manner as in Example 2, except that fluorene compound No. 7 was used as the charge transfer substance, and Vpo=-950V and E1/2=2.0 Lux·sec were obtained. Example 5 A charge carrier generation layer was formed by vacuum-depositing selenium to a thickness of 1 μm on an aluminum plate having a thickness of about 300 μm,
In addition, the same as Example 1 was used except that the fluorene compound of Compound No. 4 was used instead of the fluorene compound of Compound No. 2, and the drying conditions were changed to "drying under reduced pressure after natural drying". A charge transfer layer was formed by the method, and a photoreceptor was obtained. The Vpo of this is −
It was 1100V, E1/2 = 4.8 lux seconds. Example 6 The following perylene pigment (charge carrier generating substance) was used instead of selenium. A charge carrier generation layer was formed in the same manner as in Example 5, except that the layer thickness was about 0.3 μm, and on top of that, Compound No. 9, instead of Compound No. 4, the fluorene compound, was used. A photoreceptor was prepared in the same manner as in Example 5 except that a fluorene compound was used. of this
Vpo was −1290V and E1/2 was 8.1 Lux·sec. Example 7 Chlordiane Blue Add 158 parts of tetrahydrofuran to 1 part, grind and mix in a ball mill, and add Compound No.
A photosensitive layer forming liquid obtained by adding and mixing 12 parts of the fluorene compound No. 10 and 18 parts of the polyester resin (same as in Example 2) was applied onto the same aluminum-deposited polyester film as in Example 1 using a doctor blade. , dried at 100℃ for 30 minutes to a thickness of about 16
A photosensitive layer of μ was formed. Vpo and E were measured in the same manner as in Example 1 except that +6KV was used instead of -6KV on the obtained photoreceptor.
1/2 was measured and obtained +930V and 10.1 Lux・sec respectively. Example 8 The following azo pigment was used as a charge carrier generating substance. A photoreceptor was prepared in the same manner as in Example 7, except that the fluorene compound No. 3 was used as the charge transfer substance, and the same measurements as in Example 1 were carried out. Vpo = 1120 volts, E1 /2 = 8.5 lux·sec. Example 9 The following azo pigment was used as a charge carrier generating substance. A photoreceptor was prepared in the same manner as in Example 7, except that Compound No. 5 fluorene compound was used as a charge transfer substance, and the same measurements as in Example 1 were carried out. Vpo = 1250 volts, E1/ 2=3.1 Lux・
Got the result in seconds. Example 10 The following azo pigment was used as a charge carrier generating substance In addition, a photoreceptor was prepared in the same manner as in Example 7 except that Compound No. 9 fluorene compound was used as a charge transfer substance, and the same measurements as in Example 1 were carried out to obtain Vpo = 1000 volts and E1/ 2=9.9 Lux・
Got the result in seconds. Next, the photoreceptor obtained as described above was charged using a commercially available electrophotographic copying machine (negative charging in the case of the photoreceptors of Examples 1 to 6, positive charging in the case of the photoreceptors of Examples 7 to 10). After that, imagewise exposure is performed to form an electrostatic latent image, and then positively charged toner is applied to the photoreceptors of Examples 1 to 6, and negatively charged toner is applied to the photoreceptors of Examples 7 to 10. Developed with a dry developer containing
When the obtained image was electrostatically transferred onto high-quality paper and subsequently fixed, a clear image was formed. Similarly good results were obtained when a wet type developer was used as the developer.

[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)

[Claims] 1. General formula on a conductive support (However, R is hydrogen, C ₁ to C ₄ lower alkyl group,
Represents a _C1 to _C4 lower alkoxy group, halogen or nitro group. ) An electrophotographic photoreceptor comprising a photosensitive layer containing a fluorene compound as an active ingredient.