JPS6136231B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photoreceptor for electrophotography, and more particularly, the present invention relates to a photoreceptor for electrophotography, and more particularly, the present invention relates to a photoreceptor for electrophotography, which is characterized in that a photosensitive layer formed on a conductive support contains a compound represented by the general formula (). Regarding the body. Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been used as photodynamic 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.
This is one of the image forming methods in which a visualized image is formed 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, which requires 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
- Photoreceptor consisting of trinitrofluorene-9-one (US Patent No. 3,484,237), poly-N-vinylcarbazole sensitized with pyrylium salt dye (Japanese Patent Publication No. 48-25658), organic pigment as the main component. Photoreceptor (Japanese Unexamined Patent Publication No. 47-37543), Photoreceptor whose main component is a eutectic complex of dye and resin (Unexamined Japanese Patent Application No. 47-10735)
etc. 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. On the other hand, these excellent photoreceptors are
Although there are differences depending on the purpose or production method,
In general, excellent properties have been shown by using a photoconductive material with excellent properties. As a result of research on these photoconductive substances, the present inventors found that the diphenylmethane compound represented by the above general formula () works effectively as a photoconductive substance for electrophotographic photoreceptors, and also acts as a charge carrier. It was discovered that it is an excellent mobile substance. That is, it has been discovered that the above diphenylmethane compound can provide a photoreceptor having unexpected effects by combining it with various materials, as described below. The present invention is based on this discovery. The diphenylmethane compound of the general formula () described in the present invention can be obtained by reacting an aniline derivative with a heterocyclic aldehyde in the presence of a condensing agent. Examples of diphenylmethane compounds corresponding to the general formula () are as follows. The photoreceptor of the present invention contains the above-mentioned diphenylmethane compounds, and depending on the application of these diphenylmethane compounds, they can be used as shown in FIGS. 1 to 3. The photoreceptor shown in FIG. 1 has a conductive support 1 and a photosensitive layer 2 made of a diphenylmethane compound, a sensitizing dye, and a binder (resin). Second
The photoreceptor shown in the figure has a photosensitive layer 2' provided on a conductive support 1, in which a charge carrier generating substance 3 is dispersed in a charge transport medium 4 consisting of a diphenylmethane compound and a binder. The photoreceptor shown in FIG. 3 has a photosensitive layer 2'' consisting of a charge carrier generation layer 5 mainly composed of a charge carrier generation substance 3 and a charge transfer layer 4 containing a diphenylmethane compound on a conductive support 1. In the photoreceptor shown in Figure 1, the diphenylmethane compound acts as a photoconductive material, and the generation and transfer of charge carriers necessary for light attenuation occur through the diphenylmethane compound. Since it has almost no absorption, 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 some cases, the diphenylmethane compound forms the charge transport medium together with the binder (or binder and plasticizer), while the charge carrier generating material, such as an inorganic or organic pigment, generates the charge carriers. The charge transfer medium mainly receives charge carriers generated by the charge carrier generating substance, and
It has the ability to move. The basic condition here is that the absorption wavelength regions of the charge carrier generating substance and the diphenylmethane compound do not overlap with each other, mainly in the visible region. this is,
This is because in order to efficiently generate charge carriers in a charge carrier generating substance, it is necessary to transmit light to the surface of the charge carrier generating substance. The diphenylmethane compound according to the present invention has almost no absorption in the visible region, and when combined with a charge carrier generating substance that generally absorbs light in the visible region and generates charge carriers,
Its feature is that it works particularly effectively as a charge carrier transfer substance. In the photoreceptor shown in FIG. 3, light transmitted through the charge transport medium layer 4 reaches the charge carrier generation layer 5, and charge carriers are generated in that region, while the charge transport medium layer receives injection of charge carriers. , the generation of charge carriers necessary for photoattenuation is performed by a charge carrier generation substance, and the movement of charge carriers is performed by a charge transfer medium (mainly in which the diphenylmethane compound of the present invention works). This mechanism is similar to that of the photoreceptor shown in FIG. even here,
Diphenylmethane compounds act as charge transfer substances. To produce the photoreceptor shown in FIG. 1, a diphenylmethane compound solution containing a binder is dissolved, and if necessary, a sensitizing dye is added thereto.The solution is coated on a conductive support and dried. To produce the photoreceptor shown in FIG. 2, fine particles of a charge carrier generating substance are dispersed in a solution containing a diphenylmethane compound and a binder, and the particles are coated on a conductive support and dried.
The photoreceptor shown in Fig. 3 can be produced by vacuum-depositing a charge carrier generating substance on a conductive support, or by depositing fine particles of a charge carrier generating substance in a suitable solvent in which a binder is dissolved as necessary. After dispersion and, if necessary, surface finishing by a method such as buffing or adjusting the film thickness, a solution containing a diphenylmethane compound and a binder is applied thereon and dried. Application is carried out using 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 illustration, the thickness of the charge carrier generation layer is less than 5μ, preferably less than 2μ, and the thickness of the charge transport layer is from 3 to 50μ, preferably from 5 to 20μ. In the photoreceptor shown in FIG. 1, the proportion of the diphenylmethane compound in the photosensitive layer is 30 to 70% by weight, preferably about 50% by weight, based on the photosensitive layer. In addition, the sensitizing dye used to impart photosensitivity in the visible region is preferably 0.1 to 5% by weight based on the photosensitive layer.
It is 0.5 to 3% by weight. In the photoreceptor shown in Figure 2, the proportion of diphenylmethane compound in the photosensitive layer is
10-95% by weight, preferably 30-90% by weight,
The proportion of the charge carrier generation layer is 50% by weight or less, preferably 20% by weight or less. The ratio of the diphenylmethane compound in the charge transfer layer of the photoreceptor shown in FIG. 3 is 10
~95% by weight, preferably 30-90% by weight. Note that a plasticizer can be used together with a binder in the production of any of the photoreceptors shown in FIGS. 1 to 3. In the photoreceptor of the present invention, a metal plate or foil made of aluminum or the like, a plastic film deposited with a metal such as aluminum, or paper treated with electrical conductivity is used as the conductive support. As a 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 resin with adhesive properties can be used. As the plasticizer, halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, etc. are used. In addition, the sensitizing dyes used in the photoreceptor shown in FIG. , Rhodamine G Extra, Eosin S,
xanthene dyes like erythrosine, rose bengal, floretssen, thiazine dyes like methylene blue, cyanine dyes like cyanine,
Examples include pyrylium dyes such as 2,6-diphenyl-4-(4-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, cadmium sulfide, and cadmium-selenium sulfide; examples of organic pigments include CI Pigment Blue 25 (Color Index). Tsukusu CI 21180),
Azo pigments such as CI Pigment Red 41 (CI 21200), CI Pigment Red 52 (CI 45100), CI Basic Red 3 (CI 45210), such as CI Pigment Blue 16 (CI
7410), indigo pigments such as CI Butt Brown 5 (CI 73410) and Sea Butt Dyed (CI 73030), Argo Scarlet B (manufactured by Bayer AG), Indance Len Scarlet R (manufactured by Bayer AG), etc. Examples include perylene pigments. In addition, the photoreceptor obtained in the above manner has the following properties:
In either case, 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. are suitable, and the film thickness is preferably 1 μm or less. Copying using the photoreceptor of the present invention is accomplished by charging the surface of the photosensitive layer, exposing it to light, 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. In the following examples, all parts indicate parts by weight. Example 1 Diane Blue (CI Pigment Blue 25
98 parts of tetrahydrofuran was added to 2 parts of CI 21180), which was ground and mixed in a ball mill to obtain a charge carrier-generating pigment dispersion. This was applied onto a polyester film on which aluminum had been vapor-deposited using a doctor blade, and air-dried to form a charge carrier generation layer having a thickness of 1 μm. Next, 2 parts of diphenylmethane compound represented by structural formula (3), 3 parts of polycarbonate resin (Panlite L manufactured by Teijin),
A charge transfer layer forming liquid obtained by mixing and dissolving 45 parts of tetrahydrofuran and 45 parts of tetrahydrofuran was applied onto the above charge carrier generation layer using a doctor blade, and heated at 100°C.
It was dried for 10 minutes to form a charge transfer layer with a thickness of about 10 μm, thereby producing photoreceptor No. 1. This photoreceptor was tested for -6KV corona discharge for 20 minutes using an electrostatic copying paper tester (KK Kawaguchi Electric Seisakusho, SP428 model).
After charging it negatively for 2 seconds, it was left in a dark place for 20 seconds, and the surface potential Vpo (V) at that time was measured.
Next, the surface is irradiated with light using a tungsten lamp at an illuminance of 20 lux, the time (seconds) until the surface potential becomes 1/2 of Vpo is determined, and the exposure amount E1/2 (lux seconds) was obtained. The results were Vpo=1210V and E1/2=3.7 Lux·sec. Example 2

[Table] The above components were ground and mixed in a ball mill to obtain a charge carrier generating pigment dispersion. This was applied onto a polyester film on which aluminum was vapor-deposited 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 the diphenylmethane compound represented by structural formula (11), 3 parts of polycarbonate resin (Paralite L), and 45 parts of tetrahydrofuran was applied onto the charge carrier generation layer using a doctor blade. Apply at 100℃ using
This was dried for 10 minutes to form a charge transfer layer with a thickness of 10 μm, thereby producing photoreceptor No. 2 of the present invention. This photoreceptor was negatively charged in the same manner as in Example 1, and Vpo and E1/2 were measured. This result is Vpo=
-810V, E1/2 = 3.1 lux seconds. Example 3 On an aluminum plate having a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of 1 μm to form a charge carrier generation layer. Next, 2 parts of the diphenylmethane compound of structural formula (12), 3 parts of polyester resin (Polyester Adhesive 49000 manufactured by Dupont), and 45 parts of tetrahydrofuran were mixed and dissolved to prepare a charge transfer layer forming liquid, and this was mixed with the above charge carrier. Apply it on the generation layer (selenium vapor deposition layer) using a doctor blade,
After air drying, the photoreceptor of the present invention is dried under reduced pressure to form a charge transfer layer with a thickness of about 10 μm.
Got No.3. The Vpo and E1/2 of this photoreceptor were measured in the same manner as in Example 1. The result is
Vpo=-950V, E1/2=7.5 lux·sec. Example 4 Perylene pigment instead of selenium in Example 3 was vacuum-deposited to a thickness of about 0.3μ to form a charge carrier generation layer. Next, a photoreceptor was prepared in the same manner as in Example 3, except that the diphenylmethane compound of structural formula (20) was used as the charge carrier transfer substance.
No. 4 was prepared and Vpo and E1/2 were measured. The results were Vpo=-930V and E1/2=7.9 Lux·sec. Using photoreceptors No. 1 to No. 4 obtained in Examples 1 to 4, they were negatively charged with a commercially available copying machine, and then irradiated with light through the original image to form an electrostatic latent image. Developed using a dry developer made of positively charged toner,
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 5 A mixture of 1 part of Diane Blue (CI 21180) and 158 parts of tetrahydrofuran was pulverized and mixed in a ball mill, and then 12 parts of a diphenylmethane compound of structural formula (21) and a polyester resin (Polyester Adhesive manufactured by Dupont) were added to the mixture. The photoreceptor forming liquid obtained by adding 18 parts of Sibu 49000) and further mixing was applied onto an aluminum-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 16μ. As a result, photoreceptor No. 5 of the present invention was prepared. Using this photoreceptor,
Using the apparatus used in Example 1, the sample was positively charged by +6KV corona discharge, and Vpo and E1/2 were measured. The result is Vpo=+750V, E1/2=9.5
It was lux second. Example 6 Same as Example 5 except that α-type copper phthalocyanine was used in place of Diane Blue and the diphenylmethane compound of structural formula (26) was used in place of the diphenylmethane compound of structural formula (21). Photoreceptor No. 6 of the present invention was prepared in the same manner as in Example 5, and Vpo and E1/2 were measured in the same manner as in Example 5. The results are Vpo = +1110V, E1/2 = 10.3 Lux.
It was hot in seconds. Example 7 4-(4-N·N-dimethylaminophenyl)-
2,6-diphenylthiapyrylium chlorate
Dissolve 0.2 parts in 95 parts of dichloromethane, add and dissolve 3 parts of polycarbonate resin (Panlite L manufactured by Teijin) and 2 parts of the diphenylmethane compound of structural formula (11), and apply it onto an aluminum vapor-deposited polyester film using a doctor blade. and apply 100
The photoreceptor of the present invention is dried at ℃ for 10 minutes and has a thickness of about 10μ.
No. 7 was prepared, and Vpo and E1/2 were measured in the same manner as in Example 5. The result is Vpo=+1050V, E1/2=
It was 5.1 lux-seconds. Using photoreceptors No. 5 to 7 obtained in Examples 5 to 7,
After being positively charged using a commercially available copying machine, the original image is irradiated with light to form an electrostatic latent image, developed using a dry developer made of negatively charged toner, and the image is printed onto high-quality paper. A clear image was obtained by electrostatically transferring and fixing. A similarly clear image was obtained when a wet type developer was used as the developer. Example 8 Photoreceptor No. 8 of the present invention was prepared in the same manner as in Example 5 except that the diphenylmethane compound of structural formula (21) was replaced with 12 parts of the diphenylmethane compound of structural formula (1-b). Created. Using this photoreceptor and the apparatus used in Example 1, +
It was positively charged by 6KV corona discharge, and Vpo and E1/2 were measured. The result is Vpo=+
It was 760V, E1/2 = 10.0 lux seconds.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views enlarged in the thickness direction of an electrophotographic 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 characterized by containing a compound represented by the following general formula () in a photosensitive layer formed on a conductive support. In the formula, A represents a substituted or unsubstituted heterocyclic group, and R ₁ and R ₂ may be the same or different, and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a halogen-substituted alkyl group, or a hydroxyalkyl group. R ₁ and R ₂ may be bonded to each other to form a nitrogen-containing heterocycle. Also, R ₃
represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen.