JPS6339899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to a photoreceptor for electrophotography, and more specifically, a photoreceptor containing 1,1-bis(4-dibenzylaminophenyl) in a photosensitive layer formed on a conductive support. ) An electrophotographic photoreceptor containing a formaldehyde condensation resin of propane (hereinafter referred to as formaldehyde condensation resin unless otherwise specified).

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
- 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 consisting of dye and resin (Unexamined Japanese Patent Application No. 47-37543)
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 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 depending on the purpose or manufacturing method, they generally exhibit excellent characteristics by using an excellent photoconductive material.

Furthermore, 1,1-bis(4-dibenzylaminophenyl)propane, which is the starting material for the formaldehyde condensation resin of the present invention, is already known as an excellent charge carrier transfer substance in JP-A No. 60927/1983. . However, 1,1-bis(4-dibenzylaminophenyl)propane is easily dissolved in common organic solvents. Therefore, when a photoreceptor is created using this, the surface must be cleaned with a hydrocarbon solvent such as normal hexane or cyclohexane, or an alcohol solvent such as methanol to remove stains on the surface of the photoreceptor caused by repeated copying. It was impossible.

The present invention eliminates the above drawbacks,
1,1-bis(4-dibenzylaminophenyl)
By using a propane-formaldehyde condensation resin as a charge transfer substance, it is possible to remove stains on the surface of the photoreceptor with the above-mentioned solvent, thereby improving the deterioration in copy quality caused by repeated copying.

The formaldehyde condensation resin used in the present invention can be produced by a conventional method. That is, it is obtained by heating 1,1-bis(4-dibenzylaminophenyl)propane and paraformaldehyde in the presence of a catalyst such as sulfuric acid.

The photoreceptor of the present invention contains the formaldehyde condensation resin as described above, and depending on the application of the formaldehyde condensation resin, it can be used as shown in FIGS. 1 to 3. . The photoreceptor shown in FIG. 1 has a photosensitive layer 2a made of a formaldehyde condensation resin, a sensitizing dye, and a binder (resin) on a conductive support 1. The photoreceptor shown in FIG.
The photoreceptor shown in FIG. 2 has a photosensitive layer 2b provided on a conductive support 1, in which a charge carrier generating substance 3 is dispersed in a charge transfer medium 4 made of a formaldehyde condensation resin and a binder. The photoreceptor shown in FIG. 3 has a photosensitive layer 2c formed on a conductive support 1, comprising a charge generation layer 5 mainly composed of a charge carrier generation substance 3 and a charge transfer layer 6 containing a formaldehyde condensation resin. be.

In the photoreceptor of FIG. 1, the formaldehyde condensation resin acts as a photoconductive material, and the generation and transfer of charge carriers necessary for light attenuation occur through the formaldehyde condensation resin. However, formaldehyde condensation resin has almost no absorption in the visible region of light, so 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. be.

In the case of the photoreceptor of Figure 2, the formaldehyde condensation resin forms the charge transport medium with the binder (or binder and plasticizer), while the charge carrier generating material, such as an inorganic or organic pigment, Generate carrier. In this case, the charge transfer medium primarily has the ability to accept and transfer charge carriers generated by the charge carrier generating substance. Here, the charge carrier generating substance and formaldehyde condensation resin are
The basic condition is that the absorption wavelength regions 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 formaldehyde condensation resin according to the present invention has almost no absorption in the visible region, and when combined with a charge carrier generating material that generally absorbs visible light and generates charge carriers, it acts particularly effectively as a charge carrier transfer material. is its feature.

In the photoreceptor shown in FIG. 3, light transmitted through the charge transfer layer 6 reaches the charge generation layer 5, and charge carriers are generated in that region.On the other hand, the charge transfer layer is injected with charge carriers, and the charge carriers move. The mechanism is that the generation of charge carriers necessary for light attenuation is carried out by a charge carrier generation substance, and the movement of charge carriers is carried out by a charge transfer medium (mainly the formaldehyde condensation resin of the present invention acts). is the same as in the case of the photoreceptor shown in FIG. Again, the formaldehyde condensation resin acts as a charge transfer material.

To make the photoreceptor shown in Figure 1, formaldehyde condensation resin is dissolved in a solution containing a binder.
Further, if necessary, a solution containing a sensitizing dye is applied onto 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 formaldehyde condensation resin and a binder, and this is 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 dispersing and, if necessary, finishing the surface by a method such as buffing or adjusting the film thickness, a solution containing a formaldehyde condensation resin 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 figure, the thickness of the charge generation layer is 5μ to 0.01μ,
The thickness of the charge transport layer is preferably 2μ to 0.02μ, and the thickness of the charge transport layer is 3 to 50μ, preferably 5 to 20μ. In the photoreceptor shown in FIG. 1, the proportion of formaldehyde condensation resin 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 Fig. 2,
The proportion of formaldehyde condensation resin in the photosensitive layer is 10
~95% by weight, preferably 30-90% by weight, and the proportion of charge carrier generating material is 0.1-50% by weight, preferably 0.5-20% by weight. The rate of formaldehyde condensation in the charge transfer layer of the photoreceptor in Figure 3 is the same as in the photosensitive layer of the photoreceptor in Figure 2.
10-95% by weight, preferably 30-90% by weight.
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, a metal plate such as aluminum, a plastic film deposited with metal such as metal foil aluminum, or paper subjected to conductive treatment is used. As the binder, condensation resins such as polyamide, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyurethane, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide are used, but the insulating properties Any resin that is large and adhesive can be used. Plasticizers include halogenated paraffin, polychlorinated biphenyl,
Dimethylnaphthalene, dibutyl phthalate, etc. are used. In addition, 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; G Extra, Eosin S,
Xanthene dyes such as erythrosine, rose bengal, fluorescen; 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 substances used in the photoreceptors shown 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 Indicator). Tsukusu
CI21180) CI Pigment Red 41
(CI21200), CIA Dred 52
(CI45210), Azo pigment with carbazole bone core (Patent application 1987-8740), Azo pigment with styrylstilbene bone core (Patent application 1988-48859), Azo pigment with triphenylamine bone core (Patent application 1987-8740) 52−
45812), azo pigments with dibenzothiophene bone cores (patent application 1986-86255), azo pigments with oxadiazole bone cores (patent application 1987-77155), azo pigments with fluorenone bone cores (patent application 1986-77155), 52-87351), azo pigment with bisstilbene bone core (patent application 1972-
81790), Azo pigments with distyryloxadiazole bone cores (Patent application 1986-66711), Azo pigments with distyrylcarbazole bone cores (Patent application 1989-66711)
Azo pigments such as CI Pigment Blue 16 (CI74100), phthalocyanine pigments such as CI Pigment Blue 16 (CI74100), such as CI Butt Brown 5
(CI73410), CI Batt Dye (CI73030), and perylene pigments such as Argo Scarlet B (Bayer) and Indance Scarlet R (Bayer).

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 and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose, aluminum oxide, etc.
Further, the film thickness is preferably 1 μm or less.

To perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed, and then developed.
If necessary, transfer to paper, etc. 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.

Synthesis Example 1,1-bis(4-dibenzylaminophenyl)propane 5.9gr, paraformaldehyde
0.3gr, concentrated sulfuric acid 27.6gr in acetic acid 80ml, 100-105
The reaction was carried out at ℃ for 10 hours. After cooling, the reaction solution was poured into the water from Step 1, and the resulting yellowish white precipitate was collected, washed with water, and then dried. This precipitate was further precipitated and purified using a benzene-n-hexane system to obtain 4.2g of the desired formaldehyde condensation resin as a pale yellow precipitate (yield: 70g).
%)Obtained.

Example 1 98 parts of tetrahydrofuran was added to 2 parts of the above charge carrier-generating pigment, 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 deposited using a doctor blade, and air-dried to form a charge generation layer with a thickness of 1 μm. Next, 3 parts of formaldehyde condensation resin obtained in the synthesis example, polycarbonate resin (Panlite L manufactured by Teijin)
A charge transfer layer forming liquid obtained by mixing and dissolving 3 parts of 3 parts and 45 parts of tetrahydrofuran was applied onto the above charge generation layer using a doctor blade, and heated at 100°C.
The layer was dried for 10 minutes to form a charge transfer layer with a thickness of about 18 μm, thereby producing a laminated photoreceptor of the present invention. This photoreceptor was subjected to -6kV corona discharge for 20 seconds in a dark place using an electrostatic copying paper tester (KK Kawaguchi Electric Manufacturing Co., Ltd., model SP428), 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, and the exposure amount E1/2 (lux・Seconds) were obtained. The result is Vpo=−
It was 1000V and E1/2 = 1.7 lux seconds.

This photoconductor is negatively charged using a commercially available copying machine, then light is irradiated through the original image to form an electrostatic latent image, which is 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 2 A mixture of 1 part of the charge carrier generating pigment and 158 parts of tetrahydrofuran was ground in a ball mill.
After mixing, 20 parts of the formaldehyde condensation resin obtained in the synthesis example and 18 parts of polyester resin (Polyester Adhesive 49000 manufactured by DuPont) were added to this, and the photosensitive layer forming liquid obtained by further mixing was used for aluminum evaporation. The photoreceptor of the present invention was prepared by coating a polyester film using a doctor blade and drying at 100° C. for 30 minutes to form a photosensitive layer with a thickness of about 16 μm. This photoreceptor was positively charged by +6 kV corona discharge using the apparatus used in Example 1, with Vpo = 970 V and E1/2 = 4.3 Lux.sec.

This photoconductor is negatively charged using a commercially available copying machine, then light is irradiated through the original image to form an electrostatic latent image, which is 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.

[Brief explanation of the drawing]

1 to 3 are enlarged sectional views of an electrophotographic photoreceptor according to the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2a, 2b, 2c... Photosensitive layer, 3... Charge carrier generating substance, 4... Charge transfer medium, 5... Charge generation layer, 6... Charge transfer layer.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor characterized in that a photosensitive layer formed on a conductive support contains a formaldehyde condensation resin of 1,1-bis(4-dibenzylaminophenyl)propane.