JPH0462377B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a specific stilbene compound in its photosensitive layer. Prior Art 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 photoconductive photoreceptor is first charged in a dark place, for example by corona discharge, and then imagewise exposed to selectively dissipate the charge only in the exposed areas to obtain an electrostatic latent image. This is an image forming method in which images are developed and visualized using electrostatic fine particles (toner) made of colorants such as dyes and pigments and binders such as polymeric substances to form images. 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. Incidentally, it is a fact that each of the above-mentioned inorganic substances has many advantages and at the same time has 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 to handle and being sensitive to heat and mechanical shock, requiring careful handling. Cadmium sulfide and zinc oxide are used as binders and as photoreceptors by being dispersed in resin, but they have mechanical drawbacks such as smoothness, hardness, tensile strength, and abrasion resistance, so they cannot be used as is. 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); a photoreceptor made by sensitizing poly-N-vinylcarbazole with a pyrylium salt dye (Japanese Patent Publication No. 48-25658); (described in JP-A-47-37543), a photoreceptor whose main component is an organic pigment (described in JP-A-47-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-37543)
(described in Publication No. 10735). Although these photoreceptors have excellent properties and are considered to be of high practical value, 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. However, all of the photoreceptors mentioned so far differ depending on the purpose or manufacturing method, but in general, good characteristics can be obtained by using excellent photoconductive materials. be. Purpose It is an object of the present invention to provide a photoreceptor that can overcome the various drawbacks of the conventional photoreceptors mentioned above and fully satisfy the conditions required in electrophotography. Another object of the present invention is to provide an electrophotographic photoreceptor that is easy to manufacture, relatively inexpensive, and has excellent durability. Structure As a result of research and consideration on many photoconductive substances, the inventor found the following general formula () (In the formula, X is a halogen atom, A is hydrogen, halogen, alkyl or alkoxy group, R ₁ is an alkyl group, a substituted or unsubstituted aralkyl group,
R ₂ represents an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. ) It has been found that a stilbene compound represented by the following formula works effectively as a charge transport substance for electrophotographic photoreceptors. The present invention was completed based on these findings. That is, the present invention provides an electrophotographic photoreceptor in which a photosensitive layer containing a charge-generating substance and a charge-transporting substance is provided on a conductive support. It is characterized by containing the stilbene compound shown below. The invention will now be explained in more detail with reference to the accompanying drawings. FIGS. 1 and 2 are cross-sectional views of typical examples of photoreceptors according to the present invention, in which the numbers 1 are a conductive support, 2' and 2'' are photosensitive layers, and 3 is a A charge generating substance, 4 represents a charge transporting medium or a charge transporting layer, and 5 represents a charge generating layer.The stilbene compound represented by the general formula () used in the present invention is represented by the following general formula (). [In the formula, X is the same as the above general formula (), Y is

A triphenylphosphonium group represented by [Formula] (where Z represents a halogen ion) or a dialkyl phosphorous group represented by -PO(OR) ₂ (where R represents a lower alkyl group)] phenyl derivative and the following general formula () [In the formula, A, R ₁ and R ₂ are the same as the general formula (), l
is 0 or 1. ] It can be obtained by reacting with an aldehyde compound represented by the following. Specific examples of the stilbene compound represented by the general formula () thus obtained are shown in Table 1 below. A specific example of production is as follows. Production example 1 Diethyl 4-chlorobenzylphosphonate 26.28
g (0.1 mol) and 27.3 g (0.1 mol) of 4-N,N-diphenylaminobenzaldehyde in
Dissolve in 100 ml of dimethylformamide and add 28
% sodium methylate methyl alcohol solution
27.87g (0.15mol) was added dropwise at 25-30°C over 30 minutes. After the addition and stirring at room temperature for 2 hours, the reaction mixture was diluted with 200 ml of water. The precipitated powder was separated by filtration, washed with water, and dried to obtain a pale yellow powder. The yield was 37.4 g (yield 98%). Then, it was recrystallized from ethyl acetate to obtain pure 4-chloro-4'-N,N-diphenylaminostilbene in the form of pale yellow needle-like crystals. The yield is 33.07g (yield
86.6%), and the melting point was 164.8-165.6°C. (Corresponding to Exemplary Compound No. 12) The photoreceptor of the present invention contains one or more of the above-mentioned stilbene compounds in the photosensitive layer. It can be used as shown in FIGS. 1 and 2. The photosensitive member shown in FIG. 1 has a photosensitive layer 2' provided on a conductive support 1, in which a charge generating substance 3 is dispersed in a charge transporting medium 4 made of a stilbene compound and a binder. The stilbene compound here forms the charge transport medium 4 together with the binder (or binder and plasticizer), while the charge generating substance 3 (such as an inorganic or organic pigment)
generates charge carriers. In this case, the charge transport medium 4 is mainly responsible for receiving charge carriers generated by the charge generating substance 3 and transporting them.
The basic condition for this photoreceptor is that the absorption wavelength regions of the charge generating substance and the stilbene 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 generation material 3, it is necessary to transmit light to the surface of the charge generation material. The stilbene compound represented by the general formula () has almost no absorption in the visible region, and generally absorbs light in the visible region and generates charge carriers as a charge-generating substance 3
Its feature is that it works particularly effectively as a charge transport substance when combined with. The photoreceptor shown in FIG. 2 has a photosensitive layer 2'' formed of a laminated layer of a charge generation layer 5 mainly composed of a charge generation substance 3 and a charge transport layer 4 containing a stilbene compound on a conductive support 1. In this photoreceptor, light transmitted through the charge transport material 4 reaches the charge generation layer 5, and charge carriers are generated in that region, while the charge transport layer 4 receives injection of charge carriers. The generation of charge carriers necessary for optical attenuation is performed by a charge generation substance 3, and the transport of charge carriers is performed by a charge transport layer 4 (mainly a stilbene compound acts). The mechanism is the same as the explanation given for the photoreceptor shown in Figure 2. To actually produce the photoreceptor shown in Figure 1 of the present invention, one or more stilbene compounds and a binder are combined. The photosensitive layer 2' may be formed by dispersing fine particles of the charge generating substance 3 in a solution of the electroconductive support 1, and drying the coating on the conductive support 1. The thickness of the photosensitive layer 2' is 3 to 50 μm. , preferably 5~
20 μm is appropriate. The amount of stilbene compound in the photosensitive layer 2'' is 10 to 95% by weight, preferably 30 to 90% by weight.
The amount of the charge generating substance 3 in the photosensitive layer 2' is 0.1 to 50% by weight, preferably 1 to 20% by weight.
Weight%. Examples of the charge generating substance 3 include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium-selenium sulfide, and α-silicon; examples of organic pigments include CI Pigment Blue 25 (Color Index CI 21180) and CI Pigment Lets. CI 41 (CI 21200), CI Basic Cred 52 (CI 45100), CI Basic Cred 3 (CI 45210), azo pigment with carbazole skeleton (described in JP-A-53-95033), distylbenzene skeleton (described in JP-A No. 53-133445), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132347)
Azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-21728),
-12742), azo pigments with a fluorenone skeleton (described in JP-A-54-22834), azo pigments with a bisstilbene skeleton (described in JP-A-54-22834),
17733)) Azo pigments having a distyryl oxadiazole skeleton (described in JP-A No. 54-2129), azo pigments having a distylcarbazole skeleton (described in JP-A-54-14957), etc. azo pigments, such as CI Pigment Blue 16
Phthalocyanine pigments such as (CI 74100), indigo pigments such as C.I. Butt Brown 5 (CI 73410), C.I. Butt Dyed (CI 73030), Argo Scarlet B (manufactured by Bayer AG), Indus Thread Scarlet R (manufactured by Bayer AG), Examples include perylene pigments such as (manufactured by Co., Ltd.). Note that these charge generating substances may be used alone or in combination of two or more types. Furthermore, in order to fabricate the photoreceptor shown in FIG. 2, the charge generating substance 3 is vacuum-deposited on the conductive support 1, or fine particles of the charge generating substance 3 are deposited in a suitable form with a binder dissolved therein if necessary. The charge generation layer 5 is formed by applying a dispersion in a suitable solvent, drying it, and if necessary, performing surface finishing and film thickness adjustment by methods such as buffing. The charge transport layer 4 may be formed by applying a solution containing one or more stilbene compounds and a binder thereon and drying it. The charge generating material 3 used to form the charge generating layer 5 here is the same as that used in the description of the photosensitive layer 2'. The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm
The appropriate thickness of the charge transport layer 4 is 3 to 50 μm, preferably 5 to 20 μm. Charge generation layer 5
In the case of a type in which fine particles of the charge generating substance 3 are dispersed in a binder, the proportion of the fine particles of the charge generating substance 3 in the charge generating layer 5 is 10 to 95% by weight, preferably 50 to 90% by weight. It is about %. Also,
The amount of stilbene compound in the charge transport layer 4 is 10
~95% by weight, preferably 30-90% by weight. In the production of these photoreceptors, a metal such as aluminum or metal foil, a plastic film on which metal such as aluminum is vapor-deposited, or paper subjected to conductive treatment is used on the conductive support 1. In addition, as a binder, condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, polyvinyl ketone, polystyrene, polycarbonate, etc.
Vinyl polymers such as N-vinylcarbazole and polyacrylamide are used, but any insulating and adhesive resin can be used. A plasticizer may be added to the binder if necessary, and examples of such plasticizers include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. Furthermore, the photoreceptor obtained in the above manner has
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., and the film thickness is preferably 1 μm or less. To make a copy using the photoreceptor of the present invention, the photoreceptor surface is charged and exposed, then developed and, if necessary, transferred to paper or the like. 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. Example 1 176 parts of the charge generating substance shown in Table 2 as a charge generating substance, polyester resin (Vylon 200,
1,260 parts of a 2% tetrahydrone furan solution (manufactured by Toyobo Co., Ltd.) and 3,700 parts of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto the aluminum surface of a conductive support made of a polyester base coated with aluminum vapor. It was applied using a doctor blade and air-dried to form a charge generation layer with a thickness of about 1 μm. On the other hand, 2 parts of No. 6 stilbene compound as a charge transport substance, polycarbonate resin (Panlite)
After mixing and dissolving 2 parts of K1300 (manufactured by Teijin Ltd.) and 16 parts of tetrahydrofuran to form a solution, this was applied onto the charge generation layer using a doctor blade, heated at 80°C for 2 minutes, and then heated at 105°C. A charge transport layer having a thickness of about 20 μm was formed by drying for 5 minutes to prepare photoreceptor No. 1. Examples 2 to 10 Photoreceptors Nos. 2 to 10 were prepared in exactly the same manner as in Example 1, except that the charge generating substance and the charge transporting substance (stilbene compound) were replaced with those shown in Table 2.

【table】

[Table] Example 11 On an aluminum plate having a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of about 1 μm to form a charge generation layer. Next, 2 parts of No. 1 stilbene compound, 3 parts of polyester resin (Polyester Adhesive 49000 manufactured by Dupont), and 45 parts of tetrahydrofuran were mixed and dissolved to prepare a charge transport layer forming liquid, and this was added to the above charge generation layer (selenium). After coating with a doctor blade on the vapor deposited layer and drying naturally,
A charge transport layer having a thickness of about 10 μm was formed by drying under reduced pressure to obtain photoreceptor No. 11 of the present invention. Example 12 A mixture of 1 part of Diane Blue (same as used in Example 1) and 158 parts of tetrahydrofuran was ground and mixed in a ball mill, and then
12 parts of No. 1 stilbene compound, polyester resin (Polyester Adhesive 49000 manufactured by Dupo) 18
The photosensitive layer-forming solution obtained by adding 50% of the total amount and mixing further 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 16 μm. ,
Photoreceptor No. 12 of the present invention was prepared. Regarding photoreceptors No. 1 to 12 thus made,
Using a commercially available electrostatic copying paper testing device (Type SP 428 manufactured by KK Kawaguchi Electric Seisakusho), corona discharge of -6KV or +6KV was performed for 20 seconds to charge the paper, and then the surface was left in a dark place for 20 seconds. Potential Vpo (volts)
, then irradiate the photoreceptor surface with tungsten lamp light so that the illumination intensity is 4.5 lux, and measure the time (seconds) until the surface potential becomes 1/2 of Vpo.
was determined, and the exposure amount E1/2 (lux seconds) was calculated. The results are shown in Table-3. In addition, each of the above-mentioned photoreceptors is charged using a commercially available electrophotographic copying machine, and then light is irradiated through the original image to form an electrostatic latent image, which is developed using a dry developer. When the resulting image (toner 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 developer was used as the developer.

【table】

[Table] Effects As described above, the photoreceptor of the present invention fully satisfies the conditions required for a photoreceptor and forms clear images by using the stilbene compound represented by the above general formula (). It is something.

[Brief explanation of the drawing]

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

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor comprising a photosensitive layer containing a charge-generating substance and a charge-transporting substance on a conductive support, the charge-transporting substance is represented by the following general formula (). An electrophotographic photoreceptor comprising a photosensitive layer containing at least one stilbene compound as an active ingredient. (In the formula, X is a halogen atom, A is hydrogen, halogen, alkyl or alkoxy group, R ₁ is an alkyl group, a substituted or unsubstituted aralkyl group,
R ₂ represents an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. n represents an integer of 1 or 2. )